Sunday, February 24, 2008

A KA'NO'NA FOR THE 95 CORRIDOR

It is very unlikely this system will trend far enough south to become a major coastal Kahuna/snowstorm. The surface Low will remain over land and not transfer energy or redevelop off the Carolinas. Regardless of that, this system will have tremendous energy and impact the northern half the country from California to the Northern Plains, Great Lakes and into New England...bringing heavy snow and significant icing across many states. This Accuweather graphic breaks down the storm evolution well. A current satellite image from the west coast shows quite a bundle of energy now moving through the Rockies.

February Finale 1

SAT 2-23 7:00 PM. FEBRUARY FINALE IDEAS: The newest Euro and GFS (not shown here) is keeping the primary surface Low near West Virginia/PA Tuesday night. This is being closely followed by HPC as you would expect. You can follow the model animation here. Note that I don't hug just one exact model, I'm providing this as representative of the trend that's developed with our next storm between the GFS and Euro. Also of note are the trends with the NAO (risen to strongly positive) and PNA (still strongly positive but dropping sharply). Those indicate a more zonal or east west flow across the country, further limiting any chances for a big coastal storm. However, you will feel a SuperKahuna blast of cold air, and may set the stage for a Winter Finale as we head into the first week of March. For the sake of ravenous powderhounds, good ole' Mr. Margusity of Accuweather is keeping a distant eye on upcoming storms. You can also peruse the Eastern US Weather Forums on what others are saying about indicators of these storms or lack thereof. If you really want to take a trip down Weather Fantasyland lane, another blogger like me has..believe it or not..created an entire site just for the purpose of tracking ONE storm. Hey now, don't knock it, because regardless of the outcome, it's fun for us crazy powderhounds simply to have a potential storm to track over a 10 day period. The site title is "Storm of the Century" and the link is: http://youhavebeenwarnedmarch5th.blogspot.com/ (note: do not click on link if you're from BCPS, it will be blocked due to the domain name.) Laugh now, while you still can.

February Finale 2

SAT 2-23 8:00 AM. POST-STORM SYNOPSIS: The Mid-Atlantic and Northeast did experience a prolonged period of wintry/frozen precipitation as originally anticipated, but it ended up being much more intermittent than forecast, which reduced storm totals. Despite lower accumulations, what did fall was more than enough to make travel extremely hazardous for many areas during a majority of the storm period, so this time it seems the region-wide closings were better aligned toward safety than over-reaction.


Before we launch into another 5 day period of storm analysis, there needs to be a debriefing on what was originally said about the current event compared to what happened. Some of the ideas I've thought of initially are this: I believe the storm's underperformance was due in part to temperatures Thursday night 2/21 not decreasing as much as originally anticipated. Had it been 26 in Baltimore as forecasted for example instead of 29-30, I ascertain the changeover from light snow to sleet/freezing would not have occured as quickly from the city south and east, robbing snow potential. Instead, evaporative cooling from snow falling through those lower temperatures might have kept the temp down in the 20's all day, enhancing the freezing rain potential once it did arrive. Granted there are lots of other factors, but one cannot ignore the effect a 3-4 degree difference in temp would do at the onset of a storm.


The GFS and NAM computer models overall handled the precip onset well, and 48 hours out had finally settled on a reasonable solution, but appeared to have overdone the amount of liquid available. In addition, it was clear to all of us watching the radar that the two systems were not going to phase together. Knowing this, we should have better anticipated the dry slot was going to monkey wrench the forecast...as in robbing some areas of precip (say from Anne Arundel-Howard Counties west to Frederick County). The NWS did actually factor this into their forecasting, but the results made it appear the whole situation caught them by surprise, which in fact they knew and saw it with their own eyes. The Sterling VA NWS office only recorded a trace of snow, when the expectation was for 1-2 inches overnight. The same story was repeated in many of your backyards, and it appears no one in the "comments community" observed an accumulation greater than 1.5" right?


I welcome any of your post-storm analyses, (the what happened and why) and will be glad to post them here in the main site with you as the author. Our first responder is Kyle from Howard County, and his writeup appears below the storm grading section.

POST-STORM ACCURACY CHECK: A general lookback at (1) The original forecast (first issued publicly Sat 2/16) and; (2) The final call (posted below). Where was the call right on, where did it bust, and why?

FINAL ACCUMULATION SUMMARY: Time frame for these total storm projections is the originally forecasted period of Wednesday 12PM 2/20 to Friday 12 AM 2/22.

MAXIMUM PRECIP AMOUNTS: FORECAST 3" along the I-95 corridor from Washington to Philadelphia. 4" in central and southern Maryland, 5" in northern Virginia, western Maryland, the WV panhandle and southeastern PA. My location of Dundalk and the nearest official reporting station, BWI, will be used to grade the prediction. I project BWI will have a total of 3" of snow/frozen precip, and Dundalk, MD will max at 4". These numbers included ice. ACTUAL: Because the original call was for totals to include Wed PM to Fri PM, that includes the clipper snow Wed afternoon. Results are listed as: -Location: Forecast / Clipper amount + 2/22 amount = total / forecast = Departure in % and Final Grade. Source was NWS Public Information Statements from my link pages.

THE "BUST-APOLIS" INCLUDED:
-Dundalk (Central MD): 4 / 1.80 + .30 = 2.1 / 4 = 50 % E
-BWI Airport: 3 / 1.0 + .20 = 1.2 / 3 = 40% E
-DCA Reagan National Airport: 3 / Incomplete no data, assuming it was E
-Fairfax, Northern Virginia: 5 / 1.25 + .1 = 1.35 / 5 = 27% E
-Martinsburg, WV (Panhandle): 5 / 1.5 + .20 = 1.70 / 5 = 34% E


THE "BLUE-RIBBONS" WERE:
-Garrett County (Western MD): 5 / 3 + 2.5 = 5.5 / 5 = 90% A
-PHL Philadelphia Airport: 3 / .2 + 3.2 = 3.5 / 3 = 86 % B (over by 14%)
-Paoli (Southeastern PA): 5 / .5 + 3.5 = 4 / 5 = 80% B

POST-STORM SUMMARIES SUBMITTED BY READERS: First up. Kyle from Howard County, MD. You are welcome to submit yours via the comments and I can post them here.
1)The NAO did not trend negative, rather trended positive while the PNA Index also stayed on the positive side. We wanted a negative/positive setup.
2) A strong La Nina hasn't helped us this whole winter, however I was thinking that it actually would on this storm because of the warmer than normal gulf, but alas it didn't.
3) The jet stream seemed to be too fast and too strong, thus carrying the storm quicker than predicted, perhaps robbing some moisture gathering time.
4) Longer than desired southerly winds eating at that cold air dome.
5) Those darn mountains and mean bay: Seems like storm after storm looks good on the radar over Ohio/Tennessee until they reach the Appalachian Mts. where any storm seems to come out deformed and weaker. The bay, as Mr. Foot has mentioned, keeps on radiating heat throughout the winter, which surely didn't help our pre-storm temps.

23 comments:

terpguy said...

Looking back from Fallston:

1) The HPC called for my region to receive 00.25 to 0.50" of liquid.
My station registered 0.28 in during the storm period. Spot on...but low.

2) The dry slotting DID occur.

3) Rainshadow did a number on the "oomph" of the western-arriving moisture.

4) I STILL think that shutting down was a good call. If this event had come to the prognosticated fruition, we'd had thousands of students and staff "iced-in" in hundreds of schools.

5) We got a day off! (Well, YOU, and my son, got a day off!)





I'm off everyday!!...heh, heh, heh...

Kyle said...

I love the new graphics. The Pacific storm satellite image looks amazing, it's got that hurricane feel to it for sure. Something I wanted to bring up that I haven't seen mentioned much is the fact that Canada has a tremendous snow pack right now that ventures pretty far south (they stole our winter's snow...). Do you think the models are even accounting for this? I'm thinking that this can only help us (for snow lovers anyway). Something I'm still painfully ignorant of is what it takes to form a 'coastal low'. So, is the possible meat to this system in the prospect of a coastal low formation or from the original low coming from the west? Thanks.

terpguy said...

Kyle-(or anybody else)

Go to:

http://www.erh.noaa.gov/er/akq/wx_events/winter/www/index.html

..and read about Miller A and Miller B Cyclogenesis

TG

Kyle said...

Perfect, thanks a lot terpguy. I appreciate it. I've got some studying to do now :-D

Julee said...

I agree Mr. Foot -- that wee green/blue thing you circled DOESN'T look like much.
While the great advancing green/blue/yellow thing behind it that looks to be the size of the entire United Kingdom DOES look like much! Will THAT impact us as well?

Julee said...

Oh, and may I say ... "bust-apolis" hahahahahaha!

E.H. Boston said...

9.2" here.

A picturesque New England day today. However, I better be ready to part with it because that Tuesday system looks to be a wet one here for there is no blocking and we will see this thing gradually trend more NW as time progresses...I could see it tracking from State College to Concord, NH, maybe just NW of Boston...its going to be a wet one for all I-95 folks. Sorry.

Not our storm with this pattern...need some blocking, until then, its going to be like threading a needle...luckily, I've threaded the needle several times this winter and am now above average with over 60 inches so far IMBY.

Kyle said...

Well e.h., definitely not what I was wanting to hear, but I think that there's something still out there concerning this next system and the one following it. The models are showing some significant energy after this Tuesday storm. Or am I wrong? Also, we've already seen a 400 mile relocation of the L pressure, so a southerly shift is still possible. It seems that Boston and New York have received their decent storm this winter, but the Mid-atlantic still needs one.

Mr. Foot said...

EH is right for now, would be hard to get this to be a Coastal Kahuna, but a change to snow as the front passes is a distinct possibility, along with refreezing and super cold temps Wed-Fri

That portends a potential for a followup storm the week following, if that cold were to remain in place a couple days.

But that's another story.

Kyle said...

The week following? Are you referring to the 28th-1st or something beyond that? The 28th-1st event looks most promising right now, no?

Julee said...

Have you seen this from Accuweather regarding the upcoming storm ...

"While rain and thunderstorms are favored in the southern parts of the region, a difference in storm track of a couple of hundred miles could mean the difference between heavy rain and heavy snow for parts of the central Appalachians, mid-Atlantic and southern New England."
On next week's map, their "wintery mix" line is just above that of Mason Dixon.

I'm paying *close* attention to this storm as a visit from my sister from the 'Burgh is scheduled for Wednesday.
I want the snow. I don't want the snow.
Not fair!

Kyle said...

Wow, love the Accuweather post Julee, there may still be a chance for this one as well as the following one. I don't think this winter is over yet. Any updates tonight Mr. Foot?

Julee said...

Clearly Kyle, you and I are the p.m people.
Mr. Foot is a.m. people (two little ones to attend to).
We won't hear from him until 6 or 7 tomorrow morning.
I mean ... until WE wake up.

Wonder what that map will look like THEN?

Kyle said...

You're right Julee, I am a night owl. I suppose Mr. Foot does have a good excuse, having those kids in all :-) I guess that I am just bitter after seeing this winter thus far. This is my first winter here and I keep hearing about all these stories of great snow/ice storms in the past, but not so much this winter. However, I still have faith for this coming week and early March. My wife and friends are already having that "I want spring now!" sentiment, so they make fun of me for still wanting a snow storm, heh. But, I think we have two good chances next week of something happening. We shall see!

Mr. Foot said...

Well good morning sleepyheads!

5:30 AM..Dundalk. A blond curly thing came over to whisper at me from side of the bed. "Daddy, daddy, choca milk, choca milk."
And so the morning routine begins, but it is fun one.

And you were expecting an update at midnight! As if! Normally I'm in total power down mode by 9:30 PM. Only during Kahuna events can I tap emergency reserves to keep the candle burning.

Once the childs go to bed, then I get a little free time but just enough to read really. Hence I don't usually do a big production late at night.

Take a look at the HUGE amount of energy that's invaded the West. It is massive, covers like 5 states!
And those are big states.

Accuweather is keeping the door open because they know a possibility remains for something to turn and surprise us.

samplerknn said...

Don't think it was a total bust on Friday. Here in Norrisville (MD/PA line in Harford County) we still have most of our 3 inches covered with ice on the ground. It never got more than 33 degrees yesterday. Roads were icy at 8 yesterday. You didn't miss it entirely here...

Mr. Foot said...

Thanks for the followup analysis terp and samplerknn. I'm just glad the weather did not end up embarrassing school systems... I always feel better when the results on the ground make it obvious to anyone their school call was valid.

Busy rest of the morning and afternoon. I've put ideas out for the week ahead and feel free to add your input.

Kyle said...

::hits head on desk:: Well, there's always next winter, Mother Nature owes us. Thanks Mr. Foot for all your analysis and comments. Enjoy your Sunday.

NeedaSnowday said...

This is like a joke right??

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
357 PM EST SUN FEB 24 2008

WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD

http://forecast.weather.gov/showsigwx.php?warnzone=MDZ010&warncounty=MDC027&firewxzone=MDZ010&local_place1=Columbia+MD&product1=Hazardous+Weather+Outlook

Mr. Foot said...

You're welcome Kyle, but there is still a fair amount of winter weather left... starting with rain and snow mixed tonight in some locations. After this week's storm is through, next week continues to look interesting.

I know it is a crap shoot and we get our emotions wrapped up in expectations for a good storm. But luckily we live in an area that climatologically does get over 12" of snow each winter on average. We just don't usually get strong La Nina winters like this one so it is an outlier.

NeedaSnowday said...

Wow...John Collins on Channel 11 just showed the storms lined up..all the way to Japan... four or so that he said would travel across the US...

Mr. Foot said...

Thanks NASD..just like I said, there is loads of energy out there to cycle through in the next 2 weeks before we close this chapter in weather history.

Kyle said...

Heh, I saw that "Storm of the Century" blog within an hour of it being created, but I didn't want to post it here in an effort to not look desperate, but I guess I'm beyond that, haha. I saw it while I was on the easternuswx.com forums and, man o man, those forums can get nasty. They jump all over each other on that site, meteorologists attacking meteorologists. No way I'm posting there. Anyway, N. America has the highest snow coverage since 1966(!) yet here Maryland sits snow free. However, I'm still thinking that the huge snow pack will help keep March temps down (to the dismay of those wanting an early spring). Also looks like that clipper (weekend) could be something after all. We shall see.