Friday, March 14, 2014

Does Lucky Green = White?

Does Lucky Green = White?

Latest analysis from NOAA on this developing situation:

4:35 PM 3/15 - SNOW? RIIIIGHT. You could just hear Bill Cosby making a full standup routine on this one. But like an R & B song of recent years, "Girl you know it's true." The trend this winter has been brief warmups, followed by drastic cool downs and then, a storm. 

  • That High pressure system sliding to Eastern Canada today will begin funneling cold air southward tonight, and by Sunday afternoon we will see rain and snow mixed overspreading much of the Mid-Atlantic. 
  • Given the warm temperatures, it's obvious that the first few hours of snow will obviously have trouble sticking, or just melt on contact. 
  • By the overnight hours, snow will become heavy across much of Maryland and Virginia, and unless things change drastically, the clovers will be snow-covered Monday morning. 

We hope there are some lucky county school officials who DIDN'T FILE for the emergency waivers yet, and if so you'll be glad you waited. If not, oh well, El Nino will be back next winter anyway.

COULD IT BUST? Absolutely! There is no guarantee this pot of powderhound gold will be waiting at the end of a long winter's rainbow. March is a fickle month for storms. Let's see what the daytime highs end up Sunday. Until then, take good advantage of this pre-storm bonus today, and we'll be here tomorrow to work the storm with you. 

11:35 AM 3/15 - "Predict the High, and you predict the storm."A synopsis on the St. Patrick's Day Green-to-White Snow Gala:

  • LIQUID AMOUNTS are still expected to be 0.50-0.75" for northern Maryland, (Up to 0.50" in southern PA), and near 1.0" in southern Maryland/eastern shore. Source - NOAA: (
  • COLDER AIR will filter in starting tonight, with Sunday's highs fully 10 degrees or more colder than today's 50s. This is know as "Cold Air Damming" and can turn what looked like a mostly rain event into a snow event under the right setup.
  • WAVES OF LOW PRESSURE moving to near the coast will pull on the cold air in the High in SE Canada and wrap it down over Maryland and along the Blue Ridge. In this setup, rain Sunday changes to snow at nightfall, and continues into Monday morning. Accumulations could be as high as 4-5" across the central Mid-Atlantic by daybreak Monday under this scenario. You can review the projected development of this storm idea by scrolling through the NOAA National Forecast Maps at the WPC site. 

Our Winter Stormcast Team is developing our traditional set of scenarios and maps, which we will post later today. So for now, enjoy the sunshine while you can!

PREDICT THE HIGH... An old forecasting rule that I first learned at Penn State in the meteorology program still holds true today. Those were the days well before computer model maps could be posted online with the press of a button. At 4:30 AM in State College, PA students would enter (or rather, stumble) into the Campus Weather Service on the 6th floor of the Walker Building. There we would discover reams and reams of giant facsimile charts splayed out all over the floor. We had to quickly separate and hang up all the maps in the right location on the "Map Wall"- and THEN do the analysis. 

When forecasting for a winter storm, the FIRST THING we looked for on those black and white maps with all the wavy lines? Yep, position of the High pressure system!

Especially this time of year, if the high was in ANY way placed incorrectly for a snowstorm, that idea was off the table. Only in very rare occurrences in March would we ever see a classic High in Ontario/Quebec, with a low crawling off the Carolina coast. 

...PREDICT THE STORM Fast forward to the instagrammed, ultra-tweet, Facebook-flash world of today - there are no maps to hang on the wall anymore in some weather forecast centers. But the skills we learned still carry forward. By 8 AM on Monday morning, charts from the NOAA Weather Prediction Center have been showing for several days now the classic setup as described above, and yes, it's mid-March.

And yes, sun angle, liquid amounts, Sunday's high, the overnight low, surface wind direction, temps at 5000 feet, etc etc will ALL be important factors for how this storm evolves. But the ONE factor and trend that cannot be denied: Warm ups in our area have been fleeting, and all winter have been quickly replaced with a rush of cold air. This is due to more favorable placement of Canadian highs in recent months over a very dense and expansive snowpack. 

Unless something major changes in the setup, to this old-time forecaster, the rule looks to hold true, yes even for a mid-March storm. We'll continue watching for you, but the evidence shows that winter is not done with us. If you would like to "Predict the high" with us, we welcome your thoughts on where this puppy will end up by Monday! 

(Forecaster Foot - and Proud Penn Stater, Class of '96)

7:30 PM 3/14 - Snow probabilities rising for a potentially significant St. Patrick's Day Winter Storm -- and a second system to follow.

The enclosed graphic derived from the Winter Weather guidance suite at the NOAA NWS Weather Prediction Center has seen snow probabilities for Sunday night to Monday night rise considerably today. Earlier, our region was in a 40% probability for 4" or more. Now the same areas are in a 40% probability for 8" or more, have been advanced to HIGH for the 4" category and even the sneaky little 12" category has weasled in with a 10%!

ABOUT THE LIQUID Liquid equivalents have also risen, with WV-Northern VA-northern Maryland and Delaware fully in the 0.50-0.75" range. Southern Maryland, the lower Eastern shore and central VA are knocking on the door to 1.0" of liquid. On the western side of the Bay, our thinking is that regions along and east the I-81 corridor may see more freezing rain and sleet than snow. 

Either way you slice it, while SOME Irish eyes will be smiling on Monday, they will only be the ones who want to look upon a snowy Mid-Atlantic landscape one more time. We'll have additional updates this evening at our main site:

WHADDYA MEAN WE'RE NOT DONE? Beyond Monday, there is ANOTHER wave of low pressure lurking in the long range that may affect the region on Wednesday in the wake of the Sunday-Monday storm.

And here you all thought you had GIVEN UP snow for Lent!! See our previous posts for an overview of climate-driven scenarios for this next system.

(Forecaster Foot, Meteorologist Justin Barker and the WSC Team)

A Tale Of Two Forecasts


1:14 PM 3/14 - On this Happy "Pi" Day (since the date is 3.14), we have a special climate-focused report on the upcoming storm, titled "A Tale Of Two Forecasts."

As with every winter storm that looks to impact the Mid-Atlantic, there are always a multitude of factors that feature prominently in the final outcome. Now with late March upon us, throw 2 more factors into the forecast fire: Sun angle and climatology.

Normally, we are skeptical about any forecast for significant snow this time of year, and even in our collaboration, several members of the team are unconvinced there is strong potential for a significant winter storm Sunday into Monday. Our usual approach to resolving the many details is to present the A v. B scenarios. 

This time we will present the situation in a "climatology concerns" approach, which zeroes in on the key question: Will the climate norms of March, which do not lead to big snow events in the southern and central Mid-Atlantic -- win over the apparent favorable alignment of factors that NOAA is pointing to?

This is our "Tale of Two Forecasts" Which one are you leaning towards?

  • The A-List is for Spring-a-lings who just want to be done with Winter, and will take every shred of climate data in their favor. 
  • The B-List is for Powderhounds who believe storm dynamics can overcome climatology, much like the Palm Sunday Storm of 1942, March 18-22, 1958 or March 1993. 

CLIMATOLOGY CONCERNS - The A-list: March storms like this one tend not to pan out in much of the Mid-Atlantic because of the following factors -- 

1. Computer-generated model snowfall maps, such as those you see from the GFS, European and other models convey the impression all snow that falls will stick. This time of year that is not always true.

2. Snow to liquid ratios of 10:1 or higher are difficult to attain in March, even at night - except for interior rural areas away from metros.

3. The mid-March sun-angle is high, equal to mid-October. Daytime snow accumulation is difficult to get this time of year, and even if the sky is cloudy, solar radiation still heats the ground much more than it would between December and February.

CLIMATOLOGY CONCERNS- The B-list: About once or twice every 10 years, more January-like ingredients come into play for a storm, and can offset March climatology. These factors appear to be back on the map, such as:

1. Favorable placement of a sub-Arctic high pressure system in SE Ontario, fueling a "cold air damming" setup as noted by the Sterling NWS and the NOAA Weather Prediction Center for Sunday into Monday.

2. Copious moisture overrunning the surface high, and doing so mainly at night, when it would be more normal to expect a change of rain to snow where temperatures are seasonally still low enough for this. NOAA liquid precip shows 0.50 - 0.75 an inch!

3. Upper level energy from the southwest moving to the East coast. This energy can increase the intensity o multiple waves of low pressure near the Carolina/SE coast as well as tap cold air from with the nearby high


  • Because temps will not be in the teens like our last March snowstorm, so marginal temperatures become an issue and could negate some of the forecasted snowfall;
  • Colder, northwest suburbs west and north from the Washington, Baltimore, PhIlly metro have a better chance to get in on some snow
  • Any snow that does fall in the region Sunday night is likely to be a heavy wet gloppy snow, similar to March 25, 2013.
Let's hear from the Spring-a-lings and Powderhounds alike! Which of these two outcomes do you think is best supported by the evidence? 

Image source: NOAA WPC 

(Forecaster Foot, Mike N., Julian B., Jason M., Kate O., Connor M. and the Winter Stormcast Team

Just When We Thought It Was Safe

12:00 PM 3/14 - There's just no easy way to break this news: Snow is coming back to the Mid-Atlantic.  

If the meteorologists at the NOAA Weather Prediction Center have placed our area in a 40% probability of at least 4 inches of snow by Monday,as denoted by the green outline shown, that is big potatoes. 

There is even some Irish potatoes in there (meaning probabilities for higher amounts as well) making this a bigger deal than most thought was possible toward late March. Our best advice: Don't put away the shovel or the snowblower. 
What is currently understood to happen the next 3 days:
1. Several pulses of new cold air will overspread the region by Sunday;
2. A coastal system is expected to develop along the Carolinas;
3. A sub Arctic high pressure system is projected to be in a "favorable" location -- SE Ontario -- to provide a supply of cold air into the storm.
4. Liquid equivalents are at 0.50-0.75" and timing brings most of the precip to Maryland overnight Sunday into Monday.
Image source - Day 3 surface projection for 8 AM Monday 3/17
We agree that March storms are always problematic for many reasons: Sun angle, timing, recent temps, daylight savings affecting when the AM commute happens, etc. We'll continue outlining the scenarios for what are the most probable outcomes, so please check back again this afternoon!

(Forecasters Foot, Julian B. and the Winter Stormcast Team)


James said...

You gotta be kidding...

Unknown said...

Several factors make this completely possibile:

It's only mid-March, still winter.

21 years ago today (1993) we experienced the winter "storm of the century."

Who was it that said, "Beware the Ides of March"? (If you don't know what "ides" are, go to Wikipedia.

And finally, P. Phil got it right this time!

Keep smiling!

ravensbbr said...

You can't say Caesar wasn't warned... :-)

What?!?! said...

Dammit, more taking care of the kids...

Andy, Southern York County Pa said...

Preliminary estimates:

1-3 inches in Baltimore Metro area, with 3-5 north and west of the beltway.

Most of the region should see a solid winter weather advisory event. There could be watches for Carroll North Baltimore and Harford County. Watch criteria is 5 or more inches in MD.

Not a blockbuster but it bears more watching. This is not a final forecast as we need to look at more data, but it is the best first guess based on all current guidance and climatological factors.

Loosend said...

C'mon Andy. You have to do better than that. :) Lets make it an even 8 inches and call it a day. I'll take one more good one and then I'll go into Spring mode.

Unknown said...

I think I'm gonna throw up. This really messes up my 60th birthday plans on Monday.

Unknown said...

Happy Birthday! But please don't throw up your cake!

Keep smiling!

Unknown said...

1-3 inches for Baltimore Metro? The models may be overestimating amounts because of climatology and sun angle but that seems too low to me considering much of it will fall at night. What are you thinking would keep accumulations that low given the liquid projection by the NWS of .5-.75 inches?

Andy, Southern York County Pa said...


Fine you win! 3-5 for Baltimore metro and generally area-wide. It looks like we will have heavier rates and while the antecedent air mass and ground will be warm chewing up some of the initial snow, the rates will cool the ground overnight and we will have accumulation. Snow should continue to fall during the morning but after 9:00 am it will have a hard time adding up due to compaction from solar radiation.

This storm could throw us some twists, but for now the general idea of a 3-5 event is reasonable. If there are any changes to that general idea we will adjust accordingly. If this were a couple weeks ago I could see a 5-10 event, but with the initial air mass, ground temps, time of year, the full potential will not be realized.

Andy, Southern York County Pa said...


To have more than 3-5 we will need more qpf and higher rates. If the models up QPF and rates, then we can adjust up. .8 QPF with forecasted ground conditions and time of year would not be anymore than 5 inches in terms of ground truth could accumulate.

Amy said...

Hmm, in light of so many school closures this year I bet we are only in for a delay if the snow materializes in the 3-5"range. Falling all at night will help with accumulation, but we all know how quickly we will have rivers of melted snow during the day.

That is unless this turns into an epic March with a bit of the luck o' the Irish.

Andy, Southern York County Pa said...

Long term /Sunday night through Friday/...
highest impact time of the low pressure system will be Sunday
night into the morning morning commute. Models have come into
better agreement today with the GFS and European model (ecmwf) trending colder and
a tad further south with the track of the low which would be
favorable for accumulating snowfall especially from about 03z
through 12z Monday as temperatures fall into the 20s for most
areas. Boundary layer temperatures may hold in a bit warmer over southern
portions of the forecast area...especially southern Maryland where
mixing with rain and sleet may be possible before the changeover
occurs. Morning runs of the sref and NAM continue to show more
p-type concerns east of the Blue Ridge but given cold high
pressure locked to the north and winds backing around to the
north...tough to see how bl temperatures stay above freezing as long as
they have shown. Highest confidence for moderate to perhaps
significant snowfall is north and west of I-95/metropolitan areas...more
so north along I-81 as precipitation should be mostly snow for the entire
event. A bit concerned with the continued southward shift and a
precipitation gradient developing as occurred during a similar event a
couple weeks ago. Either way...situation is trending toward a more significant event and watches may need to be considered during the
overnight shift.

The Post 12z Monday time frame is a bit more uncertain with
potential for a dry slot/lull in the precipitation or tapering off
all together. Will continue at least likely probability of precipitation through
midday/afternoon then tapering off. Temperatures will remain well
below normal Monday.

Unknown said...

The NWS also just upped their potential accumulation numbers! They now say there is at least a 70% chance of more than 4 inches for most of Maryland. It is pretty rare to see that 3 days in advance of a snow event at any time of the year, let alone March!

NeedaSnowday said...

:::ahem::: BBR, we signed Steve Smith (check)
Next up accumulating snow ....

We used to be a team full of Lewis' a bunch of Smith's! Four!

BioPat said...

Amy I agree with the 2 hour delay idea if this storm visits us as it appears this evening. The first fe hours of snow will be lost to melting on a warmed ground then as the temps drop accumulating snow will begin. However with a 7:15 - 7:20 sunrise the snow on roads and sidewalks will quickly disappear. I think a 2 hour delay is most reasonable.

Unknown said...

I'm not at all experienced with March snowstorms but I'm hoping for more than a delay on Monday with 4+ inches of snow! I guess I could learn from this though if most snow really does melt just after sunrise. Just about all of us may learn something from this one...

MAW said...

Not to go off topic of weather; however, I would hope the powers that be make a determination of school closures based on safety and not the number of days used. Isn't that why they close. ..

Unknown said...

Yes I agree with MAW. I think people are speculating too much about why counties decide to open or close... it really is just a safety thing (or so one would hope).

Unknown said...

Joe Bastardi says he is "stumped" by this storm. We might experience something truly unique on Monday.

kristia35 said...

JB isn't all in per the usual? Wow :)

Westsidehideaway said...

The storm two weeks ago showed how hard these are to predict. It just seems to me that if it is not really really cold, the it may snow a lot but not stick much. Especially here in West Baltimore.

Tina said...

BBR, thanks for the good wishes. The nephew is still at Hopkins... CC ER didn't pack and ship... they assumed and ignored. Worse. Way worse. Yay for aunts who have some medical background and moms who go into mama-bear-mode. ::evil grin::

Amy and BP, yup, I'd put money (given the guidance we have now) on a two hour delay. Amy, when do you, er, hatch?

Here's a green G&T to the next round of models!!

Andy, Southern York County Pa said...

This storm still appears to be a WINTER WEATHER ADVISORY storm at best.

This is a complex set-up with many twists for numerical models to resolve. There are two camps at this point and both are equally plausible.

A) 3-5 inches of snow region-wide as the storm comes in overnight Sunday into Monday.

B) Sheared out system due to strong and suppressive confluence which delivers ZERO snow.

The most recent trend by has been to continue to push this storm south to the point it is not a weather maker for our area, something that has become a theme with more recent storms this late season. The nature and extent of the confluence is key and that is being handled poorly by all models.

NWS is leaning on scenario A at the moment which would deliver accumulating snow to the region by referencing the more bullish guidance.


ravensbbr said...

Andy, NAO looks to be going downward, any chance it comes into play for this one?

Tina, sorry to hear about CCER. My wife is a former medic and feels the same way about them, esp. for ped. stuff. Think they're OK for broken arms and the like, but if we have a choice...we go to JH, UMD, or Howard...

Part of the price of living out here in God's country. :-/

Westsidehideaway said...

I am not buying the 3-5 inches. Maybe it is a ploy to get the Fed Gov to shut down for the day on Monday so they can stay home and drink green beer.

Amy said...

Tina- April 11th, but we all know calendars don't make these decisions :-)

As for safety, I am not saying safety won't be a factor In the decision between a school closure and a delay, but given the time of year I don't think this snow has a lot of sticking power. Just because it comes down doesn't mean it will hang around. Hanging around is the main issue for closures.

Unknown said...

Yeah Andy I now see the potential for 0 inches of snow... the 00z Euro and 06z NAM have pushed the storm ridiculously far south. However, with how bad the modeling has been for this storm, nothing can be fully trusted. The differences from run to run are still very large.

Amy, I agree that snow can have trouble sticking in March but what you said was "In light of so many school closures this year I bet we are only in for a delay." You made mention of melting snow, but you didn't make it come across as the main reason for only delaying schools.

Unknown said...

It is also interesting to point out that while the latest runs of the Euro and NAM have pushed the storm South, the latest Canadian and GFS runs have pushed it North. Clearly there is a lot to be resolved here.

Tina said...

Nephew may come home today, not sure. Not that he has to worry about a school delay Monday or not... he's not going anywhere soon. And he's got a PILE of homework, picked up from the school, sitting on the kitchen table.

I agree with Amy's sentiment... while safety for the students would be paramount, given how many school days have been used, there'd be enormous pressure to go for a 2 hour delay if possible. At this point, it just doesn't appear to be a major snow. AND the morning sun will work quickly to melt any barely-frozen snow on roads. I'm betting the admin conversation has now turned to "no delay or 2 hours" vs. "2 hour or whole day."

Either way, the move south could mean more snow for lower DE, which is where I aim to be by Sunday night!

Andy, Southern York County Pa said...

On March 13th I tried to point out this possibility in Scenario C

"system is more sheared out delivering a low impact light snow that struggles to accumulate. This scenario almost happened last week when the confluence crushed the modeled 10-18 inches, and left us with 4-7."

Models struggle with this type of set-up and people in social media post snow maps showing 12-18 inches of snow, not remembering that MODELS ARE NEVER FORECASTS.

They are GUIDANCE, and forecasting tools. As Mr. Foot stated "predict the high, you predict the storm". A 1030 High pressure is generally not that suppressive, but its placement vis-à-vis our storm will determine its suppressive impact.

A 50 mile shift or mishandling of any of these features will yield a ground truth that is drastically different.

Once I had a look at all the players on the field it was clear to me that this would be a WINTER WEATHER ADVISORY at best, with the chance of SCENARIO C suppression.

Right now we are trying to determine the NATURE AND EXTENT of the SUPPRESSION. Models are really flip flopping around and the final placement of all the key players will determine our ground truth. 50 miles one way or the other is the difference between a plowable slush snow, and light snow showers that do little to the ground.

Unknown said...

Dang that post really seems to hammer the nail into the coffin for this storm... at least the chance of it being especially significant...

MAW said...

I always hope for a great snow event so I look at the forecast that predicts the most in hopes it is correct. When it is correct, realization sets in......I have to shovel it....all 1/10 of a mile. ...yet I still get excited when it snows

Tina said...

Ohmigod MAW!! I'm the same way. I want the snow... LOTS of snow. Then, when I'm shoveling it, I think "careful what ya wish for."


Unknown said...

Looks the same last time at most we might even end up with nothing. If it's not gonna be a lot it might as well not snow.

Westsidehideaway said...

WBAL TV is showing snow but no other specific info re totals. If the temp drops to the mid 20's on Sunday night then I will start to believe. Any warmer and I predict a bust.

Andy, Southern York County Pa said...

A general 3-5 inches is the most reasonable expectation from this system and has been for the last couple days barring extreme suppression. The 3-5 covers from the PA line to Baltimore and Washington. The confluence created by the 1030 high should not be nearly as suppressive as what we had experienced with our prior system where readings were 1040 millibars.

The thing to keep an eye on is the confluence and see how the models handle it going into the finish line, but outside of that 3-5 is a good bet.

I could see some WINTER STORM WATCHES late today followed by mainly WINTER WEATHER ADVISORIES.

I don not anticipate a WIDESPREAD 5 plus so WARNINGS will be limited, but if they are issued in spots the final verification would not likely exceed 5 inches.

WARNING CRITERIA in the LWX forecast area east of the BR is 5 inches, so it will depend on how the NWS wants to handle it. West of the BR and into PA they are 6 inches or or greater. There should be no warnings in PA due to less QPF and HIGHER WARNING CRITERIA.

Unknown said...

The NWS just released their first snowfall map. It looks like all Maryland counties excluding those immediately adjacent to the Mason-Dixon line currently meet Winter Storm Warning criteria with 4-6 inches of snow. There is a very sharp increase in accumulations to 8-10 inches once you get into Southern MD.

Andy, Southern York County Pa said...


In my opinion I would take the NWS map and cut the totals in half for this storm.

My 3-5 assessment might be a little too high. The QPF is trending down, and in order for anything to really accumulate we need rates to overcome an initial warm surface.

While 3-5 might fall it will not all add up to too much. I think we may see many WINTER WEATHER ADVISORIES, but WARNINGS will not verify.

This is a nuisance March event at best.

Westsidehideaway said...

All. How cold of you think it will get in the early hours of Monday ?

NeedaSnowday said...

::: sitting outside with kindle enjoying day :::

Thought of snow is hard to imagine.....

Unknown said...

I think the NWS' numbers are higher because they favor the GFS which has been consistently forecasting a stronger storm a bit farther north for the past few runs. The GFS may be in the minority, but it has also been the most consistent with its storm track compared to the Euro, NAM, and Canadian models.

Unknown said...

Wow even counties immediately adjacent to the Mason-Dixon line got included in the Winter Storm Watch the NWS just issued... Winter Storm Warnings may be a different story though...

Westsidehideaway said...

The Baltimore Sun web page is now flashing that Bmore will get Five Inches on Monday.


Unknown said...

The NAM continues to trend north with its 18z model run. Today's 06z run of the NAM said 0 inches for Baltimore, but its current 18z run shifts accumulating snow all the way up and beyond the Mason-Dixon line with 6 inches for Baltimore. Now you can't read the models verbatim, but it seems a trend is now developing for more snow for Central Maryland. Maybe the Baltimore Sun's advertisement of 5 inches isn't so crazy? Maybe even some Winter Storm Warnings tomorrow...?

Westsidehideaway said...

Noah. Justin Berk is saying no less than 4" for Bmore and the numbers could still go up. The ground here in West Baltimore is getting aweful warm and the crocus flowers are blanketing the lawn. Unless it gets really cold fast I am not sure how the snow will stick where I am.

Unknown said...

Justin Berk's numbers are definitely on the high end with the NWS. Most outlets are still saying 3-5" at most, with others as low as 1-4". As Berk said in his post though, it appears there is room for this storm to track north as it appeared to do with the latest NAM run. I think if the NAM's trend is picked up by other models with tonight's 00z runs, people might need to start upping their numbers... until then I view this as a VERY tough call for forecasters.

Westsidehideaway said...

Thanks Noah. Agreed. This is a tough one. Like the Foots 4:35 post just said, a lot hinges on the temps tomorrow afternoon/evening.

Unknown said...

LOL I just looked at the NWS page and saw a block of pink in Central Maryland and was like YES WINTER STORM WARNINGS... but then I realized that they were actually RED FLAG WARNINGS... oops haha

Westsidehideaway said...

I would have been confused by that one as well. It seems strange to be under winter storm watches and red flag warnings at the same time.

Unknown said...

BTW has anyone noticed the crazy amount of snow that the 18z NAM also predicts for a low passing Tuesday night? None of the other models show anything close... probably just a freak run...

Westsidehideaway said...

Is there any good site where I can watch the movement of the Canadian high?

Westsidehideaway said...

WJZ's Tim Williams is saying 2-4 inches and it is all over by 7am. I tend to agree and I am not sure the accumulation will stick to the roads. Especially here in the City.

Andy, Southern York County Pa said...


This storm had potential when there were two pieces of energy in the southwest that could have come together to form a large blockbuster storm. When it was clear they would not phase we were looking at a light to moderate event, subject to suppression.

As it stands now this would be a nice 4-8 inch storm if this were two weeks ago or earlier. With the preceding air mass being so warm, ground having had the opportunity to absorb solar radiation from late March sun angle, as well as moderate snow rates it all equals minimal accumulation.

I expect some wet and slushy roads covered by an inch or two of slush, with 3-5 inches of snow in areas primarily on grassy surfaces, grills etc. The slushy conditions will begin to abate quickly after 9:00 am on Monday as solar radiation does its work through the cloud deck.

A reasonable forecast here is 3-5 inches of snow mainly on grassy surfaces, with hazardous driving conditions generally before 9:00 am in spots due to slushy roads.

I think if you plan to leave later around 10:00 am or so roads will improve quickly in most areas. In urban heat island regions roads will be mostly wet with some slick spots for a period of time.

This to me is the hallmark of a late season nuisance snow event.

Morpheus said...

Well since my biggest totals for any storm this season was 4 inches - this could be the big storm of the year for South Bowie area! If JB's 6+ happens (I am on the northern edge of that predicted zone - this will be a blockbuster - for my hood.

Westsidehideaway said...

Many Thanks Andy. Your synopsis sounds right on for those of us in the urban space. I'll keep my eye on the outside temps and on the various forecasts from you, Noah and others tomorrow. But I agree that this will be a snow/slush event for me. Thanks.

ravensbbr said...

Not ready to bury this one yet, Joe Bastardi's snow #'s looking pretty decent this AM...

Westsidehideaway said...

Maybe so. Most are saying this will have impact south of Bmore with 2-4 inches. It is 36 degrees here at 6:40am. I'll be watching the temps all day. It will say a lot about accumulation totals.

Westsidehideaway said...

Sorry. I meant to say 3-6 inches south of Baltimore.

NeedaSnowday said...

::: raspberries ::: 2-4 is a nuisance..

Like Dory, all Powderhound's should be chanting "trend north, trend north" .....

Unknown said...

Well it appears not much changed with the overnight models. The Euro did experience a bit of a shift north with slightly higher precipitation totals, but other models seem to have largely held their ground. I think this post by the Capital Weather Gang sums up well though why you can't just read the models verbatim, a theme many forecasters have been expressing:

"About 0.1″ of the 0.59″ of precipitation shown in the GFS falls before 8 p.m., which might be in the form of rain or mixed precipitation, certainly not accumulating snow. Of the 0.35″ liquid equivalent that falls between 8 p.m. and 2 a.m., maybe about half of that converts to accumulating snow -or around 1-2″. From 2 a.m. to 8 a.m. Monday morning, just 0.13″ liquid equivalent falls – roughly another 1″ of snow. It does forecast another 0.07″ liquid equivalent precipitation after 8 a.m. Monday, which could lead to another 0.5-1″ of snow – although snow falling during the day Monday will have a hard time sticking on paved surfaces (though may continue to accumulate on the grass). That would suggest a total in the 2-4″ range from the GFS for the city, and probably 3-6″ for our colder suburbs west of town."

mayawild said...

That's disappointing. I love snow, but this just sounds messy. Ok well thanks for the update. I'll make sure I am ready for Monday morning.

Andy, Southern York County Pa said...

Sublimation, compaction, and warm surface temperatures will reduce prospects of any significant accumulation ANYWHERE east of the Blue Ridge.

I think 3-5 region wide is a strong bet, with that 3-5 verifying on unpaved surfaces only. The higher QPF will be south of Baltimore, but that is also where the warmer temperatures will verify creating a further limiting factor than north which will stand a better chance of accumulating snow due to marginally better surface conditions.

LWX is WAYYYYYY too bullish on the Winter Storm Warnings south of Baltimore as a widespread 5 or more inches will not verify in those zones.

BUT considering the timing, time of year, etc., WARNINGS are a useful tool to inform people of the impact on rush hour. I would rather overdue Warnings than underplay any storm. There will be slushy roads in many areas, and it will be slick so headlines are important.