Sunday, January 25, 2015

32 comments:
"It was the best of times, it was the worst of times."
- Charles Dickens, Tale of Two Cities

COASTAL LOW FORMATION ABOUT 6 HOURS LATER THAN EXPECTED DELAYS ARRIVAL OF SNOW IN MID-ATLANTIC. COLD AIR PRESSING SOUTH INTO EASTERLY FLOW IS NOW REACTIVATING SNOW ACROSS MARYLAND, DELAWARE AS ENERGY WORKS NORTH WHILE CAROLINA LOW FORMS.



8:30 AM 1/26 - STORM UPDATE: 

1) Easterly flow has established across the southern Mid-Atlantic while the front that was stalled earlier in central PA moved south past 12 hours. National Weather Service has extended advisories in MD and VA southward to account for likelihood of wintry precipitation impacting area farther south than first expected. 

2) The enclosed surface streamline map shows easterly flow has setup across almost the entire state. This is bringing moist Atlantic air west across Delmarva and over the Bay into the western shore. 

3) With the coastal taking a while to get underway, this easterly flow in place, and energy transfer slow from the primary lows in Virginia, we expect a light steady snow to be the rule of the day for much of the state. Roads may stay wet in eastern counties, but could become snow covered in western counties as they are in the colder sector to the north of the Low.

THE KEY FACTOR TODAY: Sun angle. Those experiencing snow will see it continue at present intensity for another 5-6 hours. 


  • Toward early afternoon it may actually decrease some. Then as the coastal Low picks up in speed and intensity, Sun angle will be dropping toward evening. 
  • After 3 PM, in a surprisingly magical way, snow will suddenly start to whiten the ground everywhere. 
  • We have seen this many times before, and with plenty of Atlantic moisture to work with, there's probably no way out of a snowy, but somewhat manageable day, in Maryland.





SIGNIFICANT WINTER STORM TO IMPACT EASTERN MID-ATLANTIC 
AND NORTHEAST SUNDAY NIGHT INTO TUESDAY
6:00 PM 1/25 - WINTER STORMCAST TEAM STATEMENT 


SYNOPSIS A highly fluid and rapidly changing forecast situation over the next 24-48 hours is going to require (or test) a high level of patience across the Northeastern U.S. At issue is an eastward traveling clipper moving along a the southern periphery of a large Arctic High pressure system. As you can see from the NOAA Surface Projection for Monday morning, this large scale dynamic will create widespread easterly flow of moist Atlantic air into the much colder Arctic air being pressed southward.

SITUATION Starting later this evening into Monday morning, this storm will first produce round of heavy snow in western and central Maryland, the West Virginia panhandle and southern PA. This first period of snow from the clipper is likely to produce 4-8" in western areas, and 2-4" near metro areas by dawn. 

* By Monday night, bands of snow should begin to fill back in over the I-95 corridor and the Eastern shore at first. An additional 3-6" is possible in counties on west side of the Chesapeake Bay, while the Philly metro region and the Upper Eastern Shore gets clocked with 6-12". 


In the event the storm slows and stalls near the Jersey coast, accumulations could be significantly higher, depending on the track of the storm.

Were that to occur, all forecasts will have to be completely revised. We seek not to over-amplify the situation, but to highlight the significant uncertainty inherent in a rapidly evolving winter storm that will cover a geographic spread larger than most hurricanes. 



COMPARISON The most basic comparison we can make to a setup resembling this could be February 17, 2003. A southern stream system overran a cold High pressure dome. What started out as snowfall projections of 3-6" early in the event ended around 18-24" as the easterly flow, southern energy and moist air all collided over the northeast. 

While this situation is much different in terms of moisture source, the fact that a High pressure looks to bleed out into the Atlantic and stall the storm somewhat may have prompted Blizzard Watches and Warnings along the Mid-Atlantic coast. That is a troubling similarity between this event and the February 2003 and February 10-11, 2010 storms.

So if you are an Emergency Manager or Facilities Operator, it looks to be the worst of times, but for Powderhounds... well, no argument there. They'll be in powder heaven celebrating the best of times. And just think, February is not even here yet! 

ROUNDUP Since this multi-day complex winter storm will have wide ranging impacts across numerous states, and many of our readers, we have assembled this listing of forecast zones from our Mid-Atlantic Team, with an enclosed link for your reference.
DISCLAIMER: Please always remember to consult official statements at your local NWS forecast office, and be advised that information we post here is for educational purposes only. Decisions by local governments are made following the latest official guidance provided by the National Weather Service and the NOAA Weather Prediction Center, as well as State Emergency Management Agencies

Saturday, January 24, 2015

31 comments:
This time in Baltimore, 
wait for "ground truth."




Latest NOAA liquid projections show 0.50" or more for southern I-95 corridor, 
in excess of 1.00" for metro areas to New York City and into most of New England

6:30 AM 1/25 - UPDATED STATEMENT IN PROGRESS


With the NWS Advisory Map lighting up overnight straight to Maine, the "Boom" scenario is becoming more probable as a faster arrival of the clipper into the Mid-Atlantic with a faster development of the coastal Low puts the I-95 corridor under an increased risk of seeing 4 or more inches of snow. 

The projected surface map for 7 PM tonight displayed left shows the situation becoming a battle for control of the "Route 30" corridor between a southward pressing Arctic High and the Low developing underneath as it slides East.

A HYBRID CLIPPER AND A SCHEMING ARCTIC HIGH:



  • Unlike traditional clippers that just swing through unimpeded by a High pressure system to the north, this one has to battle for control of the map as it moves East.
  • This will enhance Easterly flow ahead of the system while the High delivers cold Arctic air, creating an ideal arrangement for snow,
  • The outcome will be a tale of two different storms. The west to east clipper will eventually deliver it's energy to, and form a secondary coastal Low that should turn the corner and head north, bringing heavy snow to the northeast corridor.
  • We think the cards are not yet all played, though. Southward pressing Highs like this can play a steady quiet hand through the round, then shoot the moon when you least expect it. Areas south of Baltimore and on the Eastern shore should stay alert for a changing forecast if this High tries to drop that Queen of Spades.

11:00 PM 1/24 - WSC TEAM ADVISOR'S STATEMENT 

Before everyone takes off into snowfall projection land for this next event, there is an important weather concern our Advisors and Senior Forecasters wish to bring forward. This message was also shared with our partners, clients and Powderhound Insider subscribers.

BOOM OR BUST? We believe there is both an increasing probability of a blockbuster event, AND an equally strong chance for a major bust. We have seen this kind of setup before, and we've seen the negative reaction from readers when a big forecast goes belly us. Here's the issue:
  • "Clipper to Coastal" type energy transfer forecasts are fraught with peril. Sometimes they come together like a charm, other times you are expecting 6"+ of snow, and get clouds.
  • A healthy and moisture laden clipper IS coming rapidly East from the northern Plains. A large coastal storm should develop on the heels of that clipper energy as it reaches the Atlantic.
  • However, the scenario concerning us is that the Baltimore-DC region will be whipped into a frenzy just like this last dud (which we also expected to be a significant snow/ice event too....). Winter Storm Warnings will fly, then the snow will come down in sheets. Then some school districts may may pre-emptively announce closures Sunday night thinking that being proactive is always better.
Then--- at 3 AM, it shuts off-- and, crickets. The supposed energy transfer from the clipper to the coastal occurs too late. The front end snow turns out to be much less than we thought (when does that ever happen?) and there's a 12 hour window which was supposed to be all snow, and ends up as all nothing. Crews begin cleaning up, and viola! By 6 or 7 AM, many lots and roads are improving. 

But Monday would be beyond salvaging. Businesses and schools would be already closed, when they could have squeaked out a 2-hour delay or modified hours. It is true several models are showing 0.60" or more for BWI airport, and that translates to 6-8" easily, but we've seen the models overproject on snow several times this winter.

This system is not a traditional coastal, nor is it a customary clipper. It's a clipper-to -hybrid-to-coastal, and it MIGHT become an example of our old rule: "Storms from the West don't bring extra rest." (If you work in or attend a school system.)  For now, the one lesson we want to convey to all essential staff whose decisions impact their organizations:
This is one time we suggest you wait for ground truth to prove the forecast. 
Don't pre-emptively close Sunday night just because it looks like a blizzard, even if there's a Winter Storm Warning. Just wait and see what conditions look like at 5 AM Monday. Maybe this time ground truth, or lack of it, is all the observations you will need to make the call.

36 comments:
Stuck in the "Dry Slot?" 

LIFT THOSE WINTER BLUES WITH YOUR MARYLAND "FLAG IN THE FOOT"
AND BE PART OF OUR 11TH ANNIVERSARY CELEBRATION THIS WEEKEND!


Wundermap Weather Station Obs and Radar as of 7:30 AM EST 1/24


8:24 AM 1/24  - What happened to the snow (and sleet, and freezing rain...??) 


You've been caught in the most desolate land in all of forecastdom: Land of the DRY SLOT! Consider if our payback to the weather for being sacked last Sunday morning.


NO, REALLY -- What happened? The system coming north didn't tap the nearby cold as quickly as expected. Given lack of a surface High with this system, there was skepticism about it from the start by some on our team. 
  • Without the ability to really organize and pull in the colder components to our west, the eastern energy and precip generally separated. 
  • Two small surface lows formed - one off the Delmarva - one over West Virginia. This shut off the precip in between, dumping you into the Land of the Dry Slot!
  • A simpler, non-scientific approach would be to glance out the window, observe little or no winter precip, and say, "Umm, I guess you were wrong??" 


SO, WHAT'S NEXT? Snow is still expected this afternoon and early evening, but is not likely to be on the scale first projected. 
  • Temperatures are running 2-3 degrees above forecasted and the freezing line has moved into southern PA.
  • Given what we see in the short range models for Monday and beyond, that is A OK. Today may be one of those reverse surprises, where snow is falling at different times, but it doesn't negatively impact your schedule. 
  • That said, the second system coming Sunday evening into Monday looks to be coming from the Land of the Big Kahuna. With temperatures for that event heading into the 20s overnight into Monday, the outcome is going to be a lot snowier than today. Dare we use that special word reserved for only "certain storms"? You know, the word starting with "S", with the letters -ignifican- and ending in "T".

LET THE FLAG LIFT YOUR BLUES! This weekend into Monday marks the start of our team's 11th anniversary celebration. We are very excited to formally announce the first ever "Maryland Flag-in-the-Foot" embroidered hoody!. (No worries to all our other Mid-Atlantic brethren... we haven't overlooked you. Those designs will be forthcoming.)

GET ORDER DETAILS AND PRICING TODAY with a simple message to our online store. Just email to store@footsforecast.org You'll get a no pressure message back in a few minutes outlining your options and links to the store page for more information.

Thanks to all our readers for being an integral part of authentic local weather with us these 11 exciting, stormy, powdery years!! 

From all of us at the Foot's Forecast Maryland Team! 


Friday, January 23, 2015

11 comments:
"Amid The Falling Snow"
- Enya 



7:50 PM 1/23 - Good evening everybody! This is Forecaster Joe from the FF Northern West Virginia Team reporting in for the Winter Stormcast Team. 

Currently we have a LARGE swath of precipitation moving across the Mid-Atlantic region and though this is mainly rain or sleet for most, you should see a switch-over to snow as the night progresses! 

As our team indicated in our forecast maps earlier, and posted below, several inches of snow and sleet could accumulate from this storm across the region by the time it finishes passing though tomorrow night. And, if you get the chance, we welcome your storm photos submitted to our Facebook pages anytime!  Until there's enough snow to snap a photo, we invite your enjoyment of another favorite Enya tune of the team Powderhounds, "Amid the falling snow."


SURFACE TEMPERATURES AND RADAR AS OF 7:30 PM 1/23


OUR WINTER STORMCAST TEAM PROJECTIONS FROM 12:00 PM TODAY




20 comments:
"...light this up, like it's dynamite..."
-Lyrics from Dynamite by Taio Cruz




  • ONSET OF PRECIPITATION IN MID-ATLANTIC TOWARD END OF PM COMMUTE. IF YOU HAVE AN OUTDOOR TASK OR ERRAND, GET IT DONE TODAY.