Wednesday, March 21, 2018

6 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...

30 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'

5 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).