Friday, December 7, 2018

1 comment:
Too much, too soon.

5:30 AM ET FRI 12/7/18
  • HIGH PRESSURE RIDGE OVER THE NORTHERN STATES THIS WEEKEND WILL COUNTERBALANCE APPROACH OF A SOUTHERN WINTER STORM, KEEPING MAJORITY OF WINTRY PRECIP SOUTH OF THE D.C./I-66 CORRIDOR.
  • UP TO 6-12" POSSIBLE FROM SOUTHERN VIRGINIA TO CENTRAL & WESTERN  NORTH CAROLINA. Some areas will receive twice their normal seasonal snowfall in one event.  System may be an indicator of what a favorable pattern would able to produce in the Mid-Atlantic later in the season. 
  • FLURRIES OR OCCASIONAL LIGHT SNOW POSSIBLE in the DC metro area, with accumulating snow of 1-2" possible south of DC toward central Virginia. Baltimore metro area and north to PA unlikely to receive accumulation, but may see a passing snow shower at times on Sunday.

LATEST SURFACE MAP PROJECTION DEPICTS DUAL HIGH PRESSURE SYSTEMS KEEPING WINTER STORM LARGELY SOUTH OF MID-ATLANTIC, WITH HIGH IMPACT SNOWFALL CENTERED IN THE CAROLINAS.  See our previous report for probabilities. In short, it's too much cold air too soon for the Mid-Atlantic, and too much snow too soon for Carolinas.

Tuesday, December 4, 2018

4 comments:
"Here's to the ones who dream..."
- Mia in La La Land, played by Emma Stone


5:30 AM ET THU 12/6/18 - UPDATE
  • INFLUENCE OF HIGH PRESSURE OVER THE NORTHEASTERN STATES THIS WEEKEND ON A SOON-TO-DEVELOP SOUTHERN WINTER STORM LIKELY TO KEEP MOST PRECIPITATION  SOUTH OF THE D.C./I-66 CORRIDOR.
  • INCREASING POTENTIAL FOR HEAVIEST SNOW TO IMPACT SOUTHERN VIRGINIA TO NORTH CAROLINA SUNDAY INTO MONDAY.
  • PERIODS OF OCCASIONAL LIGHT SNOW POSSIBLE SUNDAY IN AREAS FROM D.C. METRO NORTH TO BALTIMORE REGION & MD/PA LINE. LOW CONFIDENCE THIS SNOWFALL PRODUCES ANY NOTABLE ACCUMULATION.


An upgraded version of the U.S. Global Forecast System, known as the GFS-FV3 model, depicts the positioning of a northern High with the southern Low as favorable for major snow in the Carolinas, but not the Mid-Atlantic. This image is for 2 PM Sunday. 
SITUATION OVERVIEW:  Have you been sniffing around for an indication of what dreams - or nightmares - may be coming this weekend? We thought you might, so our team has updated this current round of statements and scenarios for what is shaping up to be a real knockout storm for the Carolinas & southern Virginia -- and most likely a watch-and-weep event for the northern Mid-Atlantic.



The map above shows probability of 0.25" or more of liquid equivalent frozen precipitation in the "Day 4" period, which as of today would be Sunday morning into Monday morning. As snow fans can see, the areas of highest probability are centered in the Carolinas. 

WHAT ARE THE NEW SCENARIOS?
  • OPTION A - ALMOST BUT NO (70%) Strength and influence of an approaching Canadian High pressure system counteracts the developing storm as it moves from the southern Plains to the Carolina coast. Most precipitation is kept south of the Mid-Atlantic, with central Virginia seeing light to moderate snow and flurries at most for Washington, D.C.  Significant to heavy snow would impact most of the Carolinas. The model outputs for this scenario are based on trends the past few days from the U.S. Global Forecast System (GFS) and it's ensemble means.
  • OPTION B - BIG KAHUNA SURPRISE (20%) In FF Lore going back 15 years on this site, a "Big Kahuna"  is classified as a high impact major winter storm of primarily snow, with wide-ranging effects extending from coastal areas to the I-95 metro corridor to the Piedmont / Appalachian region. This scenario would be reminiscent of several infamous storms of yesteryear, such as February 17, 2003 or January 30, 2010. Both were modeled to remain south of D.C. Both changed course in the final 6 hours and plowed all the way to central PA with 6-12" or more.  The model putputs most closely matching this idea are the GGEM and Canadian.
  • OPTION C - COASTAL C-C-CRAWLER (10%) High pressure in southern Canada moving to eastern New England provides a modifying supply of cold air, starting as a dry continental air mass, then morphing into a more most, coastal version. The southern system moves to position off the Outer Banks and stalls or moves very slowly northeast. Precipitation could start as snow along I-95, then change to sleet or freezing rain as the system starts to approach the coast. Timing would slow down to impacts being felt Sunday into Monday or even Tuesday, with earlier outputs of the European model outputs showing this, which has backed off since then, hence our lowered probability. 
WHAT'S NEXT?
  • We will continue monitoring any hiccups in the model trends in the event a surprise begins brewing for Powderhounds. That's another way of rephrasing the headline to say, your best bet may be to just keep dreaming.

-FF Winter Stormcast Team, contributing to this report: 
Forecasters Foot, Jeff W., Jason M. and Keith K.


Powderhounds in upstate New York (and everywhere else) caught yearning 
to be out in the snow fun. Photo credit: Adirondack Daily Enterprise

Wednesday, November 14, 2018

3 comments:
Thursday: Bad for many, good for some

  • EARLY SEASON Snow & Ice Event ton Thursday will affect a large portion of the Mid-Atlantic, Appalachians and I-95 metro areas. 
  • Location below is Reisterstown, MD in Baltimore County a representative location for the varying impacts to occur from the Baltimore-Washington area westward to the Blue Ridge mountains.
  • Earlier than expected onset of frozen precipitation in subfreezing air temperatures right at the start of the AM commute could force many schools and organizations to delay or close, since conditions are not projected to improve until at least 12 PM or later.  Additional updates later this morning. 


Sunday, September 30, 2018

1 comment:
Wondering about winter? 
IN OCTOBER, THE ONES TO WATCH FOR SIGNS ARE 
ARCTIC SEA ICE & SIBERIAN SNOW COVER 


  • Comparison tool to analyze differences in sea ice extent between any two years. (NOAA National Snow & Ice Data Center - NSIDC)
  • Current snow cover in different regions of the Northern Hemisphere (NOAA National Ice Center - NATICE) **Note: Google may report this as an unsafe website. Trust us, it IS safe.


Sunday, September 9, 2018

1 comment:
"She's Got The Look..."
- 1988 single by Roxette (Youtube video)

FLORENCE BECOMING A HURRICANE TODAY, TAKING AIM ON SOUTHEAST & MID-ATLANTIC THIS WEEK, GROWING TO A 140 MPH CAT 4. ALL COASTAL INTERESTS: IT'S TIME TO TALK PLANNING. 


8:30 AM SUN 9/9 - By the time you read this, Florence is likely to have intensified into a Hurricane on her way to Category 3 status within a few days. Despite this being an El Nino-influenced season that generally defects most Atlantic systems due to strong westerlies off the Pacific, 2003's Isabel reminds us in these kinds of patterns, sometimes one storm can slip past the goalie. 

It happened in September of that year, and now 15 years later, it's becoming clear Florence has the look of being that storm for 2018. This system has the potential to produce significant and wide-ranging impacts on the Carolinas and Mid-Atlantic not seen since 1999's Hurricane Floyd, 2003's Isabel and could easily eclipse 2012's Sandy. 

Unless something major changes, impacts of rain, wind and inland/coastal flooding over several days are likely for anyone living east of I-81 from:
  • North Carolina north to Pennsylvania
  • The metro areas of Richmond, Washington, Baltimore, Philadelphia / New Jersey
  • The entire Delaware-Maryland-Virginia Eastern shore
LATEST OFFICIAL FORECAST DETAILS 




GFS model as example of storm position by Thu PM

8-10"+ likely from North Carolina to Baltimore

FOOT'S FINAL WORDS until the next update:
For those who lived through the impacts of either Floyd, Isabel, Irene or Sandy, review your plans and recollections to consider what you would do different this time.

Friday, April 6, 2018

11 comments:
Like a dagger in the heart of Spring
  • THIS IS NOT A PREVIEW OF STRANGER THINGS SEASON 3, IT'S REAL.
  • RARE APRIL SNOW TO AFFECT SOUTHERN MID-ATLANTIC SATURDAY
  • WEEKEND CONDITIONS TO RESEMBLE JANUARY, NOT APRIL 
  • MAPS: Below are projected surface maps for 8 AM Saturday.

THE SITUATION
  • WHAT: A reinforcing Arctic air mass will build into the region starting Friday night as waves of low pressure move northeast from the Tennessee Valley along the Arctic front.
  • WHEN: Early Saturday into daybreak, rain will mix with and change to snow from north to south, eventually overspreading the region by mid-morning.
  • HOW: Despite a strong April sun angle, high snowfall rates and dropping temperatures by mid-morning Saturday may produce light accumulations grassy & untreated surfaces. Some refreezing is likely as sub 30 F temps are expected Saturday night into Sunday AM.  
  • OPTICS: Liquid equivalents of 0.25" to 0.50" from DC to Baltimore and Philly as temperatures are dropping Sat AM indicates brief periods of heavy wet snow. It may even look like March 21 for a time, though most roads are likely to remain wet. Still, it's this kind of news that feels like a dagger to the heart of Spring....

Wednesday, March 21, 2018

10 comments:
What changed and what's next? 
SHORT TERM UPDATE FOR 8 am - 12 pm WED 3/21
7:30 AM 3/21 - WHAT CHANGED, WHY AND HOW MUCH TO GO? The attached image above is an 18-hour projection from the NOAA Short Range model depicting latest additional snowfall expected through 8 PM today. Current radar below, and below is our analysis.

Like you, we were expecting widespread snow cover from DC on north to Baltimore and east to Annapolis by now. So why not? Many areas north of I-70 and above the 695 beltway have the snow, but not what was expected. Despite the overnight timing, the reality of two back-to-back Lows obviously created a gap in precipitation that:
  • Lasted longer than forecast, and should close up by 8 AM;
  • Allowed for a warm pulse of air to embed in the lower levels overnight right where snow usually forms (around 5000 feet);
  • As seen on radar, the heavier snow pushed north of I-70 and stayed in place, whereas south of I-70 to DC, gaps opened up and allowed temps to drop, making for a glaze on most untreated surfaces. 
  • Oddly enough, snow cover would have been easier to manage, as slush can be handled better by tires and plows than a sudden glaze of ice. So where the snow cover *did not* occur as forecasted -- we are seeing the crashes and road closures more so than it seems areas with more snow cover.

WHEN WILL SNOW REALLY START TO CRANK? (For those in Frederick, Carroll, northern Baltimore, Harford and southern PA, it's more like .. when will this END??)

Monday, March 19, 2018

KITCHEN SINK...

33 comments:
It will be everything but the

FAKE VS. REAL: Can you tell which forecast is true? 
(Wonder why weather forecasting is harder than predicting politics, or teenagers? Now you know.)

SINK SCENARIO A: "Rain and sleet before 11 am, then rain, snow, and sleet between 11 am and 2 pm, then snow and sleet likely, possibly mixed with freezing rain after 2 pm. High near 36. Northeast wind 13 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 90%. Little or no ice accumulation expected. New snow and sleet accumulation of less than a half inch possible. 

OR:

SINK SCENARIO B: "Rain and snow before 2 AM, then changing to rain, sleet and snow between 2 am and 5 am, possibly mixing with freezing rain before 8 am, then rain through 11 am. High 35. Snow, freezing rain and rain likely from 11 am to 4 pm. Wind 8 to 13 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. Little or no snow and sleet accumulation."



THREE OPTIONS FOR WHAT'S GOING TO HAPPEN:
(Either way, powder cats won't be happy with it.)

  • OPTION 1: Don't Steal My Sunshine. With tropical road temps of 75-80 F today and a mid March sun angle, light precip amounts and marginal air temps in mid 30s suggest the weather impacts would be as minimal as the applicant list for a job at the White House this year. 
Any snow / sleet or freezing rain that would fall in daytime hours would quickly melt away like ice sculptures at an Australian Christmas Party. A 50% chance this comes true, with a varied collection of school districts delaying, others open on time, and everyone else complaining about something.
  • OPTION 2: Come and Get Your Love. The "ping-ping" of sleet on your window around daybreak Tuesday is first indication this day will not go as planned. Better get the high octane Starbucks. Upper level thermal profiles indicate you (if you = east of 270) get sleet- stormed for 6 hours while trying to drive on oil-greased ball bearings all over the road. 
Then you're hit with the kitchen sink of "rain and sleet, or "freezing rain, sleet and snow"; or "rain, snow and sleet" or "snow and sleet" or -- ok you get it. Either way, it's a total hot mess of a day, and then there's a Winter Storm Watch thrown in there for 3-6" of more snow starting Tuesday evening. What's not to love about this, since it has a 40% chance of being your wrinkle in time?
  • OPTION 3: Total Eclipse of the Heart. Like many famous busts in Marches gone by, you awake to the sounds of ... nothing. No precip, no rain, sleet or kitchen sink. You grudgingly head into work or school dragging your arms like Wreck-it Ralph wondering why we even bother having a winter. 
You check airline ticket costs for a romantic weekend getaway to Duluth, MN while rain and then partly cloudy pile up outside your office or classroom window. Meanwhile, this has a 10% chance of happening, since we have two Low pressures coming -- at least ONE of them will deliver frozen precip to someone in _________ (insert desired school district you prefer to be closed Tue or Wed).
WHAT'S THE BOTTOM LINE WITH THIS STORM?
  • Expect a surprising amount of change and intensity with precipitation types throughout Tuesday, with some early dismissals, delays or closures.
  • Plan for heavy, wet, wind-driven snow on Wednesday as the region will grind to a halt much like January 26, 2011.
  • Anticipate widespread refreezing and delays on Thursday as temperatures fail to cross 30 F before late morning.
- Forecaster Foot and the FF Winter Stormcasters


Sunday, March 18, 2018

GOT THIS FEELIN'

3 comments:
"I got this feelin' inside my bones..."


A PERSISTENTLY COLD PATTERN INTO NEXT WEEK WILL CREATE MULTIPLE WINTRY PRECIPITATION EVENTS THROUGHOUT THE MID-ATLANTIC. 

IT MAY BEGIN FEELING LIKE A SEQUEL TO BILL MURRAY'S GROUNDHOG DAY, WHEN YOU CONSIDER THIS FORECAST:


THE QUICK SUMMARY
  • MON-TUE: RAIN & SNOW MONDAY EVENING CHANGES TO ALL SNOW OVERNIGHT, WITH 2-4" REGION-WIDE BY TUE AM IMPACTING THE COMMUTE.
  • WED-THU: SECOND COASTAL LOW TO FORM, ADDITIONAL SNOW POSSIBLE & OVERNIGHT REFREEZING MAY IMPACT AM COMMUTES INTO THU. 
  • FRI-SAT: JANUARY-LIKE TEMPERATURES PERSIST INTO THE WEEKEND, WITH A  NEW CLIPPER & COASTAL THREAT FOR SATURDAY 3/24.

7:45 AM 3/18/18 - Just when you thought winter's luck had run out, that feeling starts creeping up on you and it makes us think maybe there is one more chance: 
  • NWS Sterling VA "Model guidance is agreeing more and more each run that we are anticipating a winter storm to some degree of magnitude."
  • NOAA Weather Prediction Center: "CURRENT DAY 2 WPC PROBABILITIES SHOW THE GREATEST CHANCE FOR SNOWFALL ACCUMULATIONS TO EXCEED 4-INCHES CENTERED ALONG THE PENNSYLVANIA / MARYLAND BORDER."

WHAT ARE THE PROJECTIONS & TIMING?

European and GFS models both show a series of coastal low pressures developing in different arrangements but each working in tandem with a High in southern Canada to introduce 32 F and below temps Tue AM and Wed AM.
  • MON NIGHT: Overnight onset & changeover indicates snow will be able to accumulate in areas north & west of the major cities, especially north of I-695, north of I-70 and west of I-270. 
  • TUE MORNING: Areas in Baltimore metro that are west of I-95 but east of I-83 may take the longest to changeover, perhaps not until just before daybreak.
  • WED MORNING: A lull in precip Tuesday night will allow colder air to filter south behind coastal # 1, reinforcing a sub-freezing surface and strengthening the potential for coastal # 2 to develop accumulating snow once again.

HOW MUCH & WHERE ?
  • Preliminary projections from the Sterling VA NWS provide two glimpses of possible snowfall. 
  • The "1 in 10 chance" map is secretly conveying to you the notion that various different runs of the European and GFS are showing significantly higher snowfall, upwards of 8-12" for the DC-Baltimore-Philly corridor. 
  • However it is too far out in time to truly nail down that potential with any certainty.




PROBABILITIES & BUST POTENTIAL?

There's always bust potential in every storm. Given this is March and surfaces are warmer, daylight is longer and cold is harder to come by, coastal Lows- or any kind of Low, has a lot to overcome for there to be actual accumulating snow on the ground. So we break down the probabilities like this - for 7 AM Tuesday morning:
  • 50% chance of at least 1" in all areas north of Route 100 in Howard County.
  • 40% chance of 2-4" all areas north & west of I-95 & north of 495.
  • 10% chance of 4" or more (all the way up to the 8-12"+ shown in some models)
Yes, we know it's March, but this time with a cold high in Canada, overnight timing and northeast winds, we feel there's enough good soul in our feet to overcome that sunshine in the pocket and deliver on the dream for one good snow.


If that's true, by Tuesday morning some of you will have nothing left to do 
but just dance, dance, dance. The rest of us who have to move in it, 
well you already know...so just imagine (another messy commute).


Friday, March 16, 2018

Remember the time

7 comments:
"Do you remember the time?"
- Micheal Jackson in the 1991 hit single Remember The Time

5:30 AM ET Fri 3/16 - With the supposed "last storm of the season" earlier this week failing to turn us into believers for one more snow, maybe you're ready to write this winter off, having dealt with enough disappointment thus far. 

That's part of the grand curse of a La Nina March: Cold at the wrong time, rain changing to snow, wind that won't leave. It's like being a senior official in the Executive branch: You don't know what's going to happen next, better check Twitter to see about the weather... or maybe your job. 

In the Mid-Atlantic, we remember the time when:
  • Snowfall occurred during the regular winter season (say, between December 1 and March 15) 
  • March was sometimes cold and windy. but usually got warmer as the month went on.
  • Snow days somehow managed to take place before winter had officially ended.         
But now, when looking at the Day 5-6-7 projections, we don't know whether to laugh or cry.
  • We don't remember a time this season when two of the biggest and most oft-cited weather computer models (the European and the U.S. Global Forecast System) were in general agreement for a potentially-long duration coastal precipitation event. Below is the GFS operational map for 8 AM next Wed 3/21. European shows a Low in almost exactly the same spot off Norfolk VA at nearly the same pressure.  

  • Some remember the last time something like this occurred so late in the season: All the way back in March 1958. We can laugh about the possibility, but you might end up crying if you had to to clear 4 feet of heavy wet snow after winter had already ended! 

(Below: March 1958 storm in southern PA)


- Winter Stormcast Team of Foot's Forecast

Thursday, March 8, 2018

Believer

14 comments:
"You made me a believer..."
 "Believer" by Imagine Dragons in the 2017 album Evolve

Tired of the way things have been this season? Any chance of "real snow" to warm the hearts 
of Powderhounds? Let's just say the pain of this winter may have been worth the wait.

THE CLAIM:

WHAT IS THE PRECEDENT?
  • The pattern we last saw from February to March of 2017 is reoccurring this season. Recall when last year, temperatures over President's weekend ramped up to 75 F under sunny skies?
  • A few weeks later, just as many had written winter off, the mid-Atlantic was clocked by a 2-day snow and ice storm on March 13-14 with January-like temperatures to seal the deal. 
  • Many schools in the Baltimore-DC region were closed 2 days in a row.

WHERE IS THE EVIDENCE?
  • Explanation: Winter 2017-18 has been influenced by the same major climate factor as last season: La Nina. The irregular cooling of the eastern equatorial Pacific in a strange way produces all kinds of stranger things in winter for the U.S. eastern seaboard: Wildly fluctuating conditions, a variety of precipitation types all in the same storm, snow in unusual places and at unusual times of the year.
  • Examples: Christmas snow in Charleston SC? How about the 70 degrees then snow 2 days later in Baltimore, only to climb back to near 80 two days after?! Oh yeah, then we had a historic windstorm, then another snow event. Tired of this pain train? It shows no sign of stopping. 
  • Evaluation: The largely overnight timing of precipitation events this season has exacted a toll on school schedules, not that any students or teachers are complaining. Though some parents are way past done with the back and forth of school being open, then closed, then open again. For now, at least most of us have 4 normal, calm weather days ahead from today to Sun 3/11.
PRELIMINARY EXPECTATIONS
  • Sunday evening 3/11: With weekend temperatures across the region to hold near January-like levels, overnight lows will have dropped back to the 20s several days in a row. A moisture laden system moving from the southern Plains is expected to gain energy from a northern Plains system. By early evening, snow should be moving northward from some type of coastal system developing along the Carolinas. 
  • Monday morning 3/12: The map above is one scenario for 8 AM Monday, with snow possible along the I-95 corridor for the morning commute. However, an old rule about winter storm forecasting will be back on the table -- "If you want snow, DON'T be in the bullseye 5 days out." Why? This allows a couple days for the computer models to resolve toward a more consistent solution -- and depict any westward drift that can occur with a coastal system. Conversely, the chances of the model showing a perfect all-out snowstorm scenario 5 days in the row is very low. Instead, we adhere to what's called the "most probable" outcome.
  • Winter weather graphics from the NOAA Winter Weather desk spell it out: The areas noted in light green currently have at least a 25% probability of 0.25" or more of liquid precipitation falling in some frozen form Sunday night into Monday. That may not seem like much, but with each passing day the probability of that scenario builds if the pattern remains consistent.

REASONING
  • By Sunday evening, we believe several key factors will be in place: A southern system able to interact with energy from the northern jet stream, evening to overnight timing of precipitation, ample moisture, a nearby High pressure system, a projected rain/snow line to setup well east of the major east coast metro areas, and all this coming on the heels of 4 days with sub-32 F overnight lows to chill the ground throughout the mid-Atlantic & mid-South.
  • A 5 day projection may not be enough to make you a believer, considering it is March and time is running out. However one question is clear: Since FF has barely posted anything this whole season, why bother now? Winter is probably over, right? Let's just say it is a case where "good things come to those who wait," because we wouldn't post a long report like this without...believing there was a good reason for it. ;-))
Forecaster Foot and the Winter Stormcast Team


Sunday, January 28, 2018

Long summer = long winter

25 comments:
"A long summer always meant a long winter to come."
from A Song of Fire And Ice, Game of Thrones: Volume 1
- by George R.R. Martin

Image credit: DeviantArt - the Battle of Winterfell in Game of Thrones
While some enjoyed this January , the powers of Deep Winter are quietly but assuredly marshaling their forces in preparation for a second invasion. The ice on our rivers and lakes has broken and melted away, and snow cover has shrunk from its 50-state conquest earlier in the month.  Here in the dead middle of winter, has the season of powder hoisted the white flag? 

As the Chinese writer and strategist Sun Tzu once said, “Appear weak when you are strong, and strong when you are weak.”  This apparent weakness in the pattern may be a clever ruse to lull you into doubting if there's any more out there. We believe winter's biggest battle is still yet to come.

Above: A long range generalized projection by the European model of mean (average) snowfall potential through February 25, due to an expected second Arctic blast arriving in early February. 

This map is also only one of four events depicted as occurring in the 30 day period from January 30 to March 2. What it means? Cold and wind took led the charge in the season's first half. Now ice and snow look to finish strong in the second half. The opening volley launches this Tuesday to Friday.
The when, where and how to be addressed in our next post later today.