Update, Morning of 1/21/2014:
January 21, 2014: Forecast for Snow
.SYNOPSIS…
LOW PRESSURE WILL INTENSIFY ACROSS NORTH CAROLINA LATER TODAY. AN
ARCTIC COLD FRONT CROSSES THE AREA THIS AFTERNOON AND EVENING…WITH
THE ENTIRE SYSTEM MOVING OFF THE MID ATLANTIC COAST TONIGHT. CANADIAN
HIGH PRESSURE BUILDS INTO THE AREA FOR THE MID WEEK PERIOD BRINGING
WELL BELOW NORMAL TEMPERATURES TO THE AREA.
&&
.NEAR TERM /THROUGH WEDNESDAY/…
HIGH IMPACT WINTER EVENT TODAY THROUGH TONIGHT…
THE BIG PICTURE…
A COLD FRONT CURRENTLY DRAPED ACROSS THE VA/NC BORDER INTO NC
EARLY THIS MORNING WILL BECOME STALLED ALONG THE CAROLINAS BY
DAYBREAK. LOW PRESSURE STARTS TO DEEPEN ALONG THIS BOUNDARY DURING
THE MORNING…WHICH WILL THEN TRACK NORTHEAST JUST OFF THE MID
ATLANTIC COAST TUE AFTN/EARLY EVENING AND THEN SHIFT WELL EAST OF
THE DELMARVA AFTER MIDNIGHT. MEANWHILE…A CANADIAN HIGH WILL
BRING A VERY COLD ARCTIC AIRMASS INTO THE NE STATES WHICH WILL
RUSH INTO THE MID ATLANTIC REGION LATE IN THE DAY THROUGH WED. THE
COASTAL LOW FINALLY MOVES INTO NOVA SCOTIA BY WED AFTN/EVENING AS
SFC HIGH PRESSURE BUILDS INTO THE MID ATLANTIC REGION FROM THE SW.
SEVERAL IMPACTS ARE EXPECTED TODAY THROUGH TONIGHT DUE TO THE
INTERACTION OF THE COASTAL LOW WITH THE VERY COLD ARCTIC AIR TO
THE NORTH. THEY ARE AS FOLLOWS:
TEMPERATURES…
HIGH TEMPERATURES WILL REACH THEIR PEAK LATE THIS MORNING WITH TEMPS
IN THE MID 30S FAR NW TO AROUND 50 FAR SE. TEMPERATURES WILL THEN
FALL THROUGH THE AFTN AS A COLD ARCTIC AIRMASS GETS PULLED INTO THE
REGION ON THE BACK SIDE OF THE COASTAL LOW. STRONG COLD AIR
ADVECTION PROCESSES TAKE OVER BY EARLY THIS EVENING AS THE LOW PULLS
AWAY TO THE NORTHEAST…CAUSING TEMPERATURES TO PLUMMET QUICKLY.
TEMPS SHOULD RANGE FROM THE LOW-MID 20S NW TO UPPER 30S/LOWER 40S
SE. OVERNIGHT LOWS ARE EXPECTED TO BOTTOM OUT IN THE SINGLE DIGITS
NW TO MID-UPPER TEENS SE.
PRECIPITATION…
PRECIPITATION MOVES INTO THE AREA FROM THE NW THIS MORNING AND
OVERSPREADS THE ENTIRE FORECAST AREA BY MID-LATE AFTN. THERE IS
AMPLE LIFT PRESENT TODAY…ESPECIALLY THROUGH THE DENDRITIC GROWTH
ZONE. AS THE WET BULB ZERO LINE FALLS BELOW ZERO THROUGH THE MORNING
IN THE NORTH…EXPECT PRECIP TO START OFF AS SNOW NW AND RAIN SE
WITH A BRIEF RAIN/SNOW MIX CAUGHT IN THE MIDDLE. WET BULB ZEROES
WILL FALL BELOW ZERO THROUGH THE AFTN IN THE SOUTH…THUS PRECIP
WILL TRANSITION FROM RAIN TO SNOW IN A NW TO SE ORIENTATION. THIS
TRANSITION LINES UP WELL WITH THE FALLING TEMPERATURES EXPECTED
TODAY. PRECIP WILL BECOME ALL SNOW BTWN 21-00Z TODAY. MEANWHILE…
THE BEST FRONTOGENESIS AND Q-VECTOR CONVERGENCE IS FOCUSED ACROSS
NRN VA AND CTRL/NRN MD THIS AFTN…WHERE THE BEST POTENTIAL FOR
ENHANCED SNOWFALL RATES WILL BE FOCUSED. A DEFORMATION ZONE WILL
ALSO DEVELOP ACROSS THE AREA THIS EVENING. THIS ZONE OF DEFORMATION
WILL OCCUR JUST BEHIND THE COASTAL LOW AS IT STARTS TO LIFT NE
AWAY FROM THE COAST AND AS THE COLD AND DRY ARCTIC AIRMASS QUICKLY
POURS INTO THE REGION FROM THE NNW. THE DEFORMATION ZONE INITIALLY
BECOMES FOCUSED OVER CTRL VA THIS EVENING (AROUND 00Z) AND THEN
SHIFTS ALONG THE COAST BY MIDNIGHT. MEANWHILE…A SECONDARY (AND
WEAKER) AREA OF FRONTOGENESIS/CONVERGENCE AND ENHANCED LIFT IS
EXPECTED TO DEVELOP ACROSS SE VA/NE NC DURING THE EVENING. THIS
WILL RESULT IN ENHANCED SNOWFALL AND QUICK SNOW ACCUMULATIONS
ACROSS THE ENTIRE FORECAST AREA DURING THIS TIME. ROADS WILL
QUICKLY BECOME SNOW-COVERED AND LEAD TO HAZARDOUS TO DANGEROUS
DRIVING CONDITIONS. PERIODS OF MODERATE SNOWFALL (POSSIBLY HEAVY)
ARE LIKELY IN THE AFOREMENTIONED AREAS DURING THIS TIMEFRAME…
ESPECIALLY ACROSS THE EASTERN SHORE WHERE THE DEFORMATION ZONE IS
STRONGEST AND ALSO DUE TO GUSTY NORTH WINDS PRODUCE AREAS OF
BLOWING SNOW (SEE WIND SECTION BELOW). AS THE LOW TRACKS NE TWD
NEW ENGLAND AFTER MIDNIGHT…SNOW WILL START TO TAPER OFF FROM
WEST TO EAST…LINGERING NEAR THE COAST BEFORE DAYBREAK. THE
POTENTIAL EXISTS FOR SNOW BANDS TO DEVELOP AS PRECIP STARTS TO
WANE…HOWEVER THE ARCTIC AIR INTRUSION MAY ACT TO SHUT OFF THE
PRECIP COMPLETELY. ALSO…A NARROW BAND OF BAY EFFECT SHOWERS ARE
POSSIBLE TONIGHT AS GUSTY NORTH WINDS AND COLD AIR MOVE OVER THE
WARMER WATERS OF CHES BAY.
TOTAL SNOWFALL AMOUNTS WILL VARY FROM 5 TO 8 INCHES ACROSS NRN
COUNTIES (GENERALLY NORTH OF INTERSTATE 64) AND THE MD/VA EASTERN
SHORE AND THE PREVIOUSLY ISSUED WINTER STORM WARNINGS WILL REMAIN IN
EFFECT FROM MID MORNING THROUGH MIDNIGHT. ACROSS PORTIONS OF CTRL/SE
VA…STORM TOTAL SNOWFALL AMOUNTS OF 3 TO 5 INCHES ARE EXPECTED AND
ADDITIONAL WARNINGS HAVE BEEN ISSUED FOR TODAY THROUGH MIDNIGHT. FOR
SW COUNTIES OF THE CWA AND NE NC…TO 1 TO 3 INCHES OF SNOWFALL IS
EXPECTED AND WINTER WEATHER ADVISORIES HAVE BEEN ISSUED FOR THIS
AREA TODAY THROUGH LATE TONIGHT. IT IS LIKELY THAT WINTER HEADLINES
WILL NEED TO BE REPLACED WITH WIND CHILL ADVISORIES TONIGHT INTO
WED AS SNOW COMES TO AN END LATER TONIGHT. PLEASE REFER TO
WWW.ERH.NOAA.GOV/AKQ FOR THE MOST UP-TO-DATE INFORMATION REGARDING
THE ADVERSE WEATHER TODAY THROUGH WEDNESDAY.
WINDS/WIND CHILL…
THE SIGNIFICANT AIRMASS DIFFERENCES BTWN THE CANADIAN HIGH AND THE
COASTAL LOW WILL CAUSE THE SFC TEMP/PRESSURE GRADIENTS TO TIGHTEN
DRAMATICALLY BY THIS AFTN. NORTH WINDS WILL GENERALLY BECOME BREEZY
WITH GUSTS TO 20 MPH ACROSS FAR S-SW COUNTIES AND UP TO 25 MPH
ACROSS CTRL VA. CLOSER TO THE COASTAL AREAS OF CHES BAY AND THE
ATLANTIC OCEAN…NORTH WINDS WILL BECOME STRONG AND GUSTY THIS AFTN
WITH SUSTAINED SPEEDS OF 25-30 MPH WITH GUSTS UP TO 35 MPH. AS STRONG
COLD AIR ADVECTION PROCESSES OCCUR THIS EVENING WITH THE MAIN ARCTIC
BLAST…NORTH WINDS WILL STRENGTHEN ALL AREAS. GUSTS OF 25 MPH ARE
ANTICIPATED ACROSS INLAND AREAS…WHILE LOCATIONS NEAR THE COAST
SHOULD EXPERIENCE WIND GUSTS OF 35-45 MPH. THE COMBINATION OF
STRONG WINDS…SNOWFALL…AND TEMPERATURES FALLING BELOW FREEZING
WILL PRODUCE AREAS OF BLOWING SNOW AND FALLING WIND CHILL VALUES.
WIND CHILLS WILL BE NEAR 20 TO THE UPPER 30S THIS AFTN…FALLING
INTO THE TEENS THIS EVENING…AND THEN DROPPING TO VALUES OF
5-10 DEGREES BELOW ZERO TO NEAR ZERO. BREEZY WINDS WILL PERSIST
THROUGH THE DAY WED…THEN GRADUALLY DIMINISH THROUGH THE AFTN AS
HIGH PRESSURE BUILDS INTO THE AREA. EXPECT WIND CHILLS TO REMAIN
IN THE SINGLE DIGITS TO LOW TEENS ON WED.
SUMMARY OF IMPACTS…
* FALLING TEMPERATURES WILL CHANGE PRECIPITATION TO ALL SNOW BY
EARLY THIS EVENING.
* SNOW WILL ACCUMULATE QUICKLY THIS EVENING AS ATMOSPHERIC CONDITIONS
ENHANCE SNOWFALL RATES.
* STRONG AND GUSTY NORTH WINDS WILL PRODUCE AREAS OF BLOWING SNOW
(ESPECIALLY NEAR THE COAST) AND ALSO WIND CHILLS THAT WILL FALL BELOW
ZERO AFTER MIDNIGHT TONIGHT.
* THE COMBINATION OF GUSTY WINDS…FALLING TEMPERATURES…AND
SNOW/BLOWING SNOW WILL CREATE HAZARDOUS TO DANGEROUS DRIVING
CONDITIONS BEGINNING THIS AFTN THROUGH EARLY WED MORNING.
FLUVANNA-PRINCE EDWARD-CUMBERLAND-GOOCHLAND-NOTTOWAY-AMELIA-
POWHATAN-CHESTERFIELD-HENRICO-DINWIDDIE-PRINCE GEORGE-
CHARLES CITY-NEW KENT-
INCLUDING THE CITIES OF…FARMVILLE…GOOCHLAND…CREWE…
COLONIAL HEIGHTS…RICHMOND…PETERSBURG…HOPEWELL
736 AM EST TUE JAN 21 2014
…WINTER STORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EST
TONIGHT…
A WINTER STORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EST
TONIGHT.
* AREAS AFFECTED: PORTIONS OF CENTRAL VIRGINIA…INCLUDING METRO
RICHMOND.
* HAZARDS: SNOW…BLOWING SNOW…AND GUSTY WINDS.
* ACCUMULATIONS: 3 TO 6 INCHES.
* WINDS: NORTH WINDS OF 15 TO 20 MPH WITH GUSTS TO AROUND 30 MPH
THIS AFTERNOON AND EVENING.
* TEMPERATURES AND WIND CHILL: TEMPERATURES WILL FALL BELOW
FREEZING THIS AFTERNOON…THEN FALL TO AROUND 10 DEGREES BY
EARLY WEDNESDAY MORNING. THE COMBINATION OF GUSTY WINDS AND
COLD TEMPERATURES WILL PRODUCE WIND CHILL VALUES TO AROUND
FIVE BELOW ZERO BY WEDNESDAY MORNING.
* TIMING: SNOW WILL BEGIN IN THE WEST THIS MORNING WITH RAIN OR
A RAIN/SNOW MIX FARTHER EAST. PRECIPITATION WILL CHANGE TO ALL
SNOW DURING THIS AFTERNOON. THE PERIOD OF HEAVIEST SNOWFALL IS
EXPECTED THIS AFTERNOON THROUGH EARLY THIS EVENING.
* IMPACTS: ROADS WILL BECOME SNOW COVERED AND SLIPPERY. THE
COMBINATION OF SNOW AND GUSTY WINDS WILL PRODUCE BLOWING SNOW
THAT WILL REDUCE VISIBILITY TO BELOW ONE MILE AT TIMES. TRAVEL
CONDITIONS WILL BECOME DANGEROUS THIS AFTERNOON THROUGH THIS
EVENING.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
A WINTER STORM WARNING FOR HEAVY SNOW MEANS SEVERE WINTER WEATHER
CONDITIONS ARE EXPECTED OR OCCURRING. SIGNIFICANT AMOUNTS OF SNOW
ARE FORECAST THAT WILL MAKE TRAVEL DANGEROUS. ONLY TRAVEL IN AN
EMERGENCY. IF YOU MUST TRAVEL…KEEP AN EXTRA FLASHLIGHT…
FOOD…AND WATER IN YOUR VEHICLE IN CASE OF AN EMERGENCY.
1/20/2014 Forecast Grpahics and Discussion:
An arctic front is set to move through the area tonight and stall across North Carolina. Once it passes and stalls south of Central Virginia, a clipper system will pass nearby Tuesday morning into the afternoon that will likely give the area some accumulating snow. A winter storm watch was issues for most of the immediate metro Richmond area:
DORCHESTER-WICOMICO-SOMERSET-INLAND WORCESTER-MARYLAND BEACHES- FLUVANNA-LOUISA-CUMBERLAND-GOOCHLAND-HANOVER-CAROLINE-AMELIA- POWHATAN-CHESTERFIELD-HENRICO-KING WILLIAM-KING AND QUEEN-ESSEX- WESTMORELAND-RICHMOND-NORTHUMBERLAND-LANCASTER-CHARLES CITY- NEW KENT-MIDDLESEX- INCLUDING THE CITIES OF...CAMBRIDGE...SALISBURY...CRISFIELD... PRINCESS ANNE...SNOW HILL...OCEAN CITY...LOUISA...GOOCHLAND... ASHLAND...COLONIAL HEIGHTS...RICHMOND...TAPPAHANNOCK 352 AM EST MON JAN 20 2014 ...WINTER STORM WATCH IN EFFECT FROM TUESDAY MORNING THROUGH TUESDAY EVENING... THE NATIONAL WEATHER SERVICE IN WAKEFIELD HAS ISSUED A WINTER STORM WATCH...WHICH IS IN EFFECT FROM TUESDAY MORNING THROUGH TUESDAY EVENING. * AREAS AFFECTED: PORTIONS OF CENTRAL AND EASTERN VIRGINIA...AND THE LOWER EASTERN SHORE. * HAZARDS: SNOW. * ACCUMULATIONS: SNOWFALL ACCUMULATIONS OF 3 TO 6 INCHES OF SNOW ARE POSSIBLE ACROSS THE WATCH AREA. * WINDS: NORTH WINDS WILL AVERAGE 10 TO 20 MPH...WITH GUSTS TO AROUND 30 MPH EXPECTED TUESDAY AFTERNOON AND EVENING. * TIMING: LIGHT SNOW WILL BEGIN BY MID MORNING ON TUESDAY...CONTINUING INTO EARLY TUESDAY EVENING. THE PERIOD OF HEAVIEST SNOWFALL IS EXPECTED TUESDAY AFTERNOON THROUGH EARLY EVENING. * IMPACTS: ACCUMULATING SNOWFALL COULD CAUSE PERIODS OF HAZARDOUS TRAVEL ACROSS THE AREA TUESDAY AFTERNOON AND EVENING. PRECAUTIONARY/PREPAREDNESS ACTIONS... A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT SNOW ACCUMULATIONS THAT MAY IMPACT TRAVEL. CONTINUE TO MONITOR THE LATEST FORECASTS. Discussion from the NWS:.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... BUSINESS LOOKS TO PICK UP ACROSS THE LOCAL AREA TO BEGIN THE DAY TUESDAY. MODELS CONTINUE TO TREND TOWARDS A MORE MOIST SOLUTION AS THE SHORTWAVE/CLIPPER AMPLIFIES SE INTO THE CAROLINAS THROUGH THE DAY TUESDAY BEFORE EJECTING THE SYSTEM NORTHEAST TOWARDS ATLANTIC CANADA EARLY WEDNESDAY. OVERALL, WHILE THE NAM TRACKS THE SYSTEM FARTHEST SOUTH, WE STAYED CLOSER TO A GGEM/UKMET/GFS BLEND WHICH IS FARTHER NORTH WITH THE SLUG OF BEST CONVERGENCE/LIFT. RIGHT ENTRANCE REGION OF H3 (UPPER JET), ALONG WITH 285K PRESSURE ADVECTION/RH FIELD PER THE ABOVE MODEL CONSENSUS WOULD PAINT A VERY MESSY PICTURE LATE TUESDAY MORNING THROUGH EARLY EVENING AS THE CLIPPER AND TRAILING COLD FRONT MOVE THROUGH. STRONG CAA STILL PROGGED TO KICK IN DURING THE AFTN. THUS...EXPECT MAX TEMPS AROUND NOON/SHORTLY THEREAFTER SOUTHEAST WITH FALLING READINGS IN THE AFTN. POPS HAVE BEEN SHUNTED UPWARD INTO HIGH LIKELY RANGE ACROSS THE FAR NORTHERN CWA FOR TUESDAY. WHEREAS SNOW ACCUMULATIONS WILL LIKELY BE A BIT MORE CUT AND DRIED FARTHER NORTH AS ARCTIC AIR SURGES SOUTHEAST, THEY APPEAR TO BE A BIT MORE TRICKY ACROSS OUR AREA, ESPECIALLY ALONG AND SOUTH/EAST OF THE RICHMOND METRO. ONE LOOK AT LATEST SREF PLUMES SHOWS A WIDE ARRAY OF POTENTIAL SOLUTIONS FORWARDED BY MEMBER ENSEMBLES...WHICH DOES NOT INSPIRE FORECAST CONFIDENCE, ESPECIALLY GIVEN THE FACT THAT MODEL SOLUTIONS WERE LESS THAN ENTHUSIASTIC ABOUT QPF TOTALS JUST 12-18 SHORT HOURS AGO. HOWEVER, WITH BETWEEN 0.2 AND 0.4" OF QPF...AND SNOW-LIQUID RATIOS A BIT HIGHER THAN NORMAL CONSIDERING THE IMMINENT INCURSION OF AN ARCTIC AIRMASS...WARNING CRITERIA SNOWS ARE CERTAINLY FEASIBLE AS BEST FGEN FORCING PUSHES ACROSS THE REGION TUESDAY AFTN. WL GO WITH WINTER STORM WATCH OVER RICHMOND METRO NORTH TO THE LOWER EASTERN SHORE...INCLUDING NORTHERN NECK. FARTHER SOUTH, WEAKER PCPN RATE AWAY FROM BEST FGEN FORCING WILL MAKE ACCUMULATING SNOWFALL A BIT MORE PROBLEMATIC. CERTAINLY, THESE AREAS WILL BE MONITORED...BUT GIVEN PREFERRED MODEL SOLUTION, EXPECT BEST SNOWFALL TOTALS NORTH OF RIC METRO OVER TO THE NORTHERN NECK AND EASTERN SHORE. A GENERAL 3-6 INCLUDED IN WSW...BUT COULD CERTAINLY SEE HIGHER TOTALS OVER NORTHEASTERN MOST PORTIONS OF THE AREA. THE SNOW SHOULD END ACROSS THE NORTH EARLY TUESDAY EVENING WITH MUCH COLDER ARCTIC AIR CONTINUING TO MOVE INTO THE AREA. ATTENTION QUICKLY SHIFTS TO THE SOUTHEAST, WITH POTENTIAL FOR A QUICK (LIGHT) SNOW ACCUMULATION ACROSS HAMPTON ROADS AND TIDEWATER AREAS. WIND TRAJECTORY QUICKLY TURNS 350-360 AS THICKNESSES CRASH AND H92-85 TEMPS FALL TO ~-18C. STILL QUITE WARY OF POTENTIAL FOR BAY ENHANCEMENT OF SNOW SHRAS TUESDAY NIGHT...AND HV GONE WITH SNOW WORDING ACROSS THE TIDEWATER. CERTAINLY NOT CERTAIN ENOUGH FOR ANY HEADLINES AT THIS STAGE...BUT JUMP IN SREF PROBABILITIES AND SYNOPTIC SETUP WARRANTS A BIT HARDER WORDING IN DIGITAL FORECAST. BECAUSE OF THE COMBINATION OF A STRONGER SURFACE LOW (TIGHTER GRADIENT BRINGS MORE WIND) AND EXPECTED SNOW ON THE GROUND, TEMPS HAVE BEEN DROPPED FOR TUESDAY NIGHT AND ESPECIALLY WED/THU NIGHT. EXPECT WIND CHILL VALUES TO NUDGE BELOW ZERO TUESDAY NIGHT AND EARLY WED. STRONG CAA KICKS IN CONTINUES WED MORNING BEFORE SLOWLY DIMINISHING LATE. DESPITE PLENTY OF SUNSHINE...A VERY COLD DAY IS EXPECTED. THE STRONG/GUSTY N-NW FLOW WILL KEEP TEMPS ABOUT 1.5-2 STD DEV BELOW NORMAL. KEPT SC CLOUD DECK ALONG THE COASTAL ZONES ERY WED AS H8 TEMPS PLUMMET TO -16 TO -18C. ALTHOUGH NOT THE PERFECT WIND DIRECTION (340 VS 360)...SOME BAY EFFECT STREAMERS AND ADDITIONAL SNOW SHRAS POSSIBLE ACROSS HAMPTON ROADS WED MORN. KEPT SLIGHT CHC POP FOR NOW. HIGHS WEDNESDAY IN THE 20S.