Saturday, January 7, 2017

Southern Storms & Northern Air

6 comments:
Southern Storms & Northern Air
  • HEAVY SNOW FROM NORTH CAROLINA TO EASTERN VIRGINIA,  THE VA/MD EASTERN SHORE AND SOUTHERN MD WILL CONTINUE THROUGH TODAY, 6" OR MORE IN MANY AREAS SOUTH OF DOVER, DE TO ST. MARY'S MD TO RICHMOND AND NORFOLK. See Wakefield VA NWS 1/7 Snow Briefing
  • FROM DC METRO NORTH TO BALTIMORE AND PHILADELPHIA, DRY AIR ON A NORTH WIND HAS BEEN IMPEDING SATURATION OF AIR, DELAYING ONSET OF SNOW UNTIL MID-MORNING SATURDAY. 
  • AREAS WHERE SNOWFALL HAS BEEN DELAYED BY DRY AIR CAN EXPECT UP TO 1 INCH BEFORE SYSTEM BEGINS PULLING NORTHEAST THIS AFTERNOON.
  • ROGUE BANDS OF SNOW MOVING THROUGH SOUTHERN & EASTERN PA MAY PRODUCE AN UNEXPECTED 1 INCH OR MORE ON SATURDAY .




NWS WINTER WEATHER MAP SUITE
To locate these resources, click on your local NWS office site and scroll down to the icon titled "Winter Weather" that looks like this image.



CENTRAL & SOUTHERN PENNSYLVANIA

BALTIMORE-WASHINGTON REGION

SOUTHEAST PA & DELMARVA PENINSULA

EASTERN VIRGINIA TO NORTH CAROLINA






Monday, January 2, 2017

Help is almost here.

20 comments:
Help is almost here.
  • WHITE IN THE WINTER NIGHT ACROSS THE MID-ATLANTIC REGION STARTING LATE THIS AFTERNOON FOR WV AND WA, REACHING I-95 CORRIDOR BY 8 PM. SNOW OVERNIGHT OF 1" OR MORE BETWEEN PA/MD LINE & DC METRO
  • CRITICAL END-POINT TIMING OF SNOWFALL ON FRIDAY MORNING WILL INFLUENCE HOW FRIDAY AM COMMUTE PLAYS OUT. PREPARE FOR DELAYS AS EVEN LIGHT AMOUNTS WILL PRODUCE SLIPPERY CONDITIONS OVERNIGHT.
  • A WEEK OF MOISTURE TRANSPORT LIKE THIS ACROSS THE U.S., FOLLOWED BY ARCTIC AIR MAY LEAD TO A PROLONGED PERIOD OF WINTRY PRECIPITATION IN THE EASTERN STATES  STARTING AFTER JANUARY 15.

4:00 AM ET 1/5 - It's time to move your snow plans into action. Although tonight's event for the Mid-Atlantic is not slated to produce major impact, for portions of our region the actual timing of the snowfall will be problematic for the Friday AM commute. This will include most of the MD Eastern shore and the I-66 to I-70 corridors & I-95 corridors. Main issues next 24 hours:

  • Two moisture sources = better snow chances. Two disturbances moving quickly toward the region will interact for a 12 hour period from 4 PM tonight to 4 AM Friday. The first is an upper level disturbance streaking east from the central plains. The second will be a developing coastal Low near the Carolinas.
  • How much snow? Not much, but very fine grained. The intensity of upper level cold was reported by NWS office in the west to allow this system a snow-to-liquid ratio of nearly 40 to 1! If you are a snow science enthusiast, that is like John Madden's Ultra Winter Fantasy Football. You try the math! Even just 0.05" of snow with a 30:1 ratio aloft could easily produce 1.5" at the surface. 
  • Fine flakes mean road war. This type of snow gets in every crack, nook and cranny of road surfaces because the extremely fine grained nature of the snow allows it to adhere instantly and quickly create a slick, thin sheen upon contact. With temperatures not slated to rise about 32 F for  most of the region west of the I-95 corridor until at least 12 PM, improvement in road conditions may not occur until late morning.   
  • What about timing? An NWS Hourly Weather Chart for Eldersburg, MD below is a representative location for the overall impact we believe will be observed from DC metro and the 270 corridor to eastern WV -- to central MD and southern PA.

HOW MUCH, WHERE AND WHEN? Snow maps from the Winter Weather sections at the Sterling VA NWS (Baltimore/Washington) and the Philadelphia/Mt. Holly NWS below:


Sunday, January 1, 2017

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