Sunday, March 3, 2019

5 comments:
"IT CAN HAPPEN TO YOU..."
- Lyrics from the 1984 single by Yes (Youtube video)

UPDATE AS OF 10:30 AM SUN 3/3

  • WET SNOW to overspread the region through afternoon, becoming heavy after 2 PM with snowfall rates reaching 1"  per hour anytime after 4 PM in many locations north and west of the 95 corridor. 
  • HEAVIEST SNOW expected from 4 PM through 9-10 PM for areas south of the PA turnpike to just west of 95,  then tapering to light snow until midnight. For areas south of 95 to the DC metro area / northern VA and southern MD, rain/snow mixed may briefly turn to snow/sleet toward evening, with 1-2" possible before ending. 
  • MONDAY COMMUTE? With widespread snow cover and a north wind after the system departs, we expect temperatures to remain in the upper 20s to 30 F  through 9 AM, which may lead to refreezing until sun angle can warm exposed surfaces.



  • AREAS SOUTH OF I-70 TO THE BALTIMORE/DC METRO & 95 CORRIDOR, rain changing to snow by evening with 1-4" depending on location & proximity to Chesapeake Bay.

PREVIOUS UPDATES BELOW

STORM TIMING ANALYSIS & PRECIP OPTIONS

  • U.S. GFS-FV3 model depiction for 7 PM Sunday shows moderate to heavy snow in all locations north & west of the 95 corridor



SUNDAY AM to PM: Snow north of I-70 by mid-AM
  • COMPUTER MODELS: The GFS remains more consistent than the European with the colder solution for snow or a snow/mix. Several other models have come into line with the GFS, thus is the preferred projection as noted above.
  • TIMING: Snow should be light for the first few hours, with sun angle reducing accumulation potential on most roads until after 2 PM Sunday.
South of I-70: Preliminary forecast 
  • Morning snow showers are possible for a few areas but light rain/snow is expected to develop by Sunday afternoon. 
  • It could very well become mixed with snow or sleet at times as highs reach the mid to upper 30s, upper 30s to lower 40s south and east. 
  • The lower to mid-30s for our friends in PA.
SUNDAY NIGHT: Snow north of 70 & it could happen south
  • FOR AREAS NORTH OF I-70 & west of I-83: Away from Philadelphia, Baltimore, Washington will see heavy snow developing by mid-afternoon. Up to 5" is likely and amounts may exceed 6" before midnight along the PA/MD line.
  • FOR AREAS SOUTH of I-70: the Arctic air tries to push in from the northwest, rain could once again transition over to snow/sleet and freezing rain and begin to accumulate. As the song lyrics go, if cold air works into the region earlier than expected, heavy snow could shift south-- so yes, it could happen to you. 
  • PRELIMINARY SNOWFALL TOTALS: From I-70 south to I-95, 2-4" is possible Sunday evening into early Monday morning. From the 95 corridor south to US-50 in southern Maryland/DC region, 1-3" is possible. 
  • CONSIDERATIONS: A lot will depend on the temperature fall hour-by-hour overnight and also how much precipitation is still feeding into Maryland as the air cools to near-freezing. especially north and west of 95 as many could be traveling through at least a couple inches of snow and perhaps some ice. From this vantage point though, there's still much uncertainty as to precipitation type and potential accumulations.
MONDAY: Clearing by sunrise, refreezing by evening.
  • MORNING: Morning clouds giving way to partly sunny skies wind and cold. NW winds 20-25 mph. Highs in the upper 30s but falling through the day. 
  • IMPACT ON SCHOOLS? Like the lyrics suggest, it's a constant fight, we're pushing the needle to the red. Who knows who's right, so the best we can do is look up, look down, look out and look around. It'll be a crazy world outside...
  • NIGHT: Partly cloudy skies with lows in the upper teens to lower 20s. Mid teens for PA.

Winter Stormcast Team: 
Lead Forecaster Jeff W., Contributors R. Foot, Ira W., J. McDuffie

Friday, March 1, 2019

4 comments:
"YOU MIGHT THINK..."
- Song & lyrics the 1984 album Heartbeat City by the Cars

UPDATED 7:00 AM FRI 3/1

  • RISING PROBABILITY A DISRUPTIVE, EVOLVING WINTER STORM WILL AFFECT MAJORITY OF THE NORTHERN & EASTERN U.S SATURDAY - MONDAY.
  • MID-ATLANTIC: RAIN ON SUNDAY 3/3 MAY CHANGE TO HEAVY SNOW BY EVENING FOR AREAS NORTH & WEST OF 95 CORRIDOR TO THE 81 CORRIDOR.
  • SNOWFALL: U.S. & EUROPEAN MODELS HAVE AT LEAST 2" FOR THE CITIES, WITH POTENTIAL FOR 5" OR MORE IN RURAL AREAS FROM NORTHERN VA TO WESTERN MD INTO SOUTHERN / CENTRAL PA.
  • TEMPERATURES: FROM TUE - FRI, TEMPS DROP 20 DEGREES BELOW NORMAL FOR EARLY MARCH. HIGHS IN MOST AREAS FROM DC NORTH IN THE 20S TO NEAR 30, LOWS IN SINGLE DIGITS TO TEENS.
(Below - U.S. Watch/Warning Map that will show official statements as weekend progreses)



THE CHANGING POTENTIAL  : NWS hourly chart for Clarkesville MD in NW Montgomery County, Maryland. We believe will be on the diving line between snow to the west and rain to the East.



Wednesday, February 20, 2019

IS IT BECOMING A BIG KAHUNA?

18 comments:
IS IT BECOMING A BIG KAHUNA?

UPDATED AS OF 6:30 AM WED 2/20



  • CURRENTLY - Current radar view at this hour shows moderate to heavy snow falling down towards Charlottesville VA and just north of Richmond. Snow will continue to move north over the next several hours, reaching the DC metro now through 7 AM and the Baltimore metro 8-9 AM.
  • THROUGH THE MORNING - We expect snow rates to pick up quickly in all areas no later than 9 AM, and begin falling at a 1 inch per hour or more at times through 12 PM. If you have somewhere to be, we recommend getting there early to avoid what will look like a "wall of snow" moving over the area after 9 AM.
  • SLEET & SNOW RATES - After 12 PM today, sleet should mix in with the snow, but just before that there may be an hour or more of high snowfall rates where heavy "banding" sets up on radar. Under these locations, you may see another 1-2" additional to what you received before Noon.
  • BIG KAHUNA OR NOT? - To qualify for this unofficial label we assign to potentially big storms, it would have to produce 6 inches or more in a majority of locations where the snow is occurring. If the heavy banding depicted on short range models does develop, areas expecting 4" could easily end up with 6" or more. We think that remains a strong possibility between 10 AM and 2 PM. Bottom line: This has a good chance of going full Kahuna in some of our backyards, but not in all of them -- so when it does we want to celebrate! Let us know the moment you cross 6".


PREVIOUS UPDATE 4:30 PM TUE 2/19


FF Winter Stormcast Team Public Messages
  • STORM MODE: For access to the latest official details on your local forecast for storm timing and precise accumulations, visit the links highlighted above specific to your region.
  • TEAM SNOW MAP: Our regional snow & ice map is posted below with revisions if needed around 11 AM and 6 PM.
  • SCENARIO SUMMARY: Our overview of the A,B,C scenarios from earlier posts will be consolidated into a summary statement with the snow map. The synopsis is we believe this event will encompass features of all three scenarios: Starting as a "Big Kahuna" with heavy snow the first 8-10 hours, then turning to an "Icecapade" for another 6-8 hours, and ending as a Cold, Curmudgeony Rain" into Thursday morning.


Latest Snow & Ice Maps from the Sterling VA NWS