For posterity sake, here is the latest forecast for downtown Richmond related to tonight’s snowfall.

NWS Forecast Discussion:

.NEAR TERM /THROUGH THURSDAY/…

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UPDATED AT 11AM…
BROAD AREA OF WINTRY PRECIP ASSOCIATED WITH STRENGTHENING LOW
PRESSURE HAS LIFTED NWD INTO SRN NC AS OF 11 AM. 12/12Z KMHX
SOUNDINGS SHOWS VERY MOIST PROFILE…EXCEPT A NARROW DRY LAYER
BETWEEN 950-900MB. EXPECT THIS DRY LAYER TO BECOME OVERWHELMED
RATHER QUICKLY THIS MORNING AS OVERRUNNING MOISTURE SURGES NWD.
HAVE MAINTAINED INHERITED POP GRIDS…ALTHOUGH TRENDS INDICATE
THE PRECIP MAY MOVE IN SLIGHTLY FASTER.

OTHERWISE…PER LATEST MODEL TRENDS AND UPSTREAM SFC
OBSERVATIONS…WILL BEGIN TO TREND THE CURRENT FORECAST SLIGHTLY
WARMER DUE TO THE LOCATION OF THE H85 LOW AND THE WARM NOSE. THE
RESULT WILL PUSH THE MIXED BAG OF PRECIP WWD WITH AN INCREASING
RISK OF ACCUMULATING ICE OVER THE LOWER PIEDMONT INTO SOUTH
CENTRAL VA (ALONG AND WEST OF THE INTERSTATE 95 CORRIDOR). THIS
WILL ALSO IMPACT SNOWFALL AMOUNTS WITH SLIGHTLY LOWER ACCUMULATIONS
(PERHAPS 4-8 INCHES ON THE EAST SIDE OF RICHMOND). THERMAL
PROFILES SUGGEST A CHANGE FROM SNOW TO FREEZING RAIN LATE TONIGHT
BEFORE TRANSITIONING TO RAIN EARLY THURSDAY MORNING. WILL WAIT TO
UPDATE SNOW/QPF/WX FORECAST UNTIL ALL THE 12Z GUIDANCE COMES
IN…BUT DO ANTICIPATE A SHIFT TO THE WEST WITH WINTRY PRECIP.

EMPHASIS STILL REMAINS ON THE ONSET OF PRECIP AS HEAVY SNOWFALL IS
EXPECTED TO QUICKLY SPREAD OVER THE SRN LOCAL AREA. FOR MORE
INFORMATION…PLEASE REFER TO THE PREVIOUS DISCUSSION.

.PREV DISCUSSION…
LATEST WX ANALYSIS FEATURES STATIONARY FRONT ALONG THE GULF COAST
THIS MORNING, WITH A DEVELOPING AREA OF LOW PRESSURE ALONG THE
FRONT JUST OFF THE WESTERN GULF COAST. TO THE NORTH, ~1037MB SFC
HIGH PRESSURE IS IN PLACE OVER NEW ENGLAND, AND IS RIDGING DOWN
THE LEE SIDE OF THE APPALACHIANS. WV/IR SAT SHOWING OVERRUNNING
MSTR PUSHING INTO THE WESTERN CAROLINAS THIS MORNING…WITH ONLY A
SHIELD OF HIGH CLOUDS APPROACHING FROM THE SW.

OVERVIEW…
HIGH CONFIDENCE FOR A SIGNIFICANT WINTER STORM IMPACTING THE AKQ
CWA TODAY. WINTER STORM WARNINGS NOW IN EFFECT FOR NORTHAMPTON
NC/GREENSVILLE/SUSSEX…ALONG WITH INHERITED WINTER STORM WARNINGS
FOR WESTERN HALF OF THE AREA…VA NORTHERN NECK AND DORCHESTER
COUNTY MD. SEE WBCWSWAKQ FOR LATEST INFO.

PRECIPITATION…
EARLY MORNING REGIONAL RADAR MOSAIC SHOWS THAT SWATH OF PCPN
ALREADY PUSHING FROM THE DEEP SOUTH INTO THE CAROLINAS AT SUNRISE.
PRECIP CHCS QUICKLY INCREASE TO CATEGORICAL FROM SOUTH TO NORTH BY
MID-LATE AFTN /JUST AFTER SUNSET TONIGHT FAR NORTH/. THICKNESSES
SUGGEST PCPN STARTS OFF AS SNOW, THEN BECOMES A MIXTURE OF PCPN
ACROSS SERN AREAS WITH SERN COASTAL AREAS GOING OVER TO RAIN BY
00Z. HIGHS L-M30S EXCEPT M-U30S SERN COASTAL AREAS.

CHALLENGING FCST WRT PINNING DOWN SNOW AMTS…AND EXACTLY WHEN
THE HEAVIEST SNOW OCCURS. OVERALL, STILL EXPECT AREAS ALONG AND TO
THE WEST OF I-95 SHOULD BE SEEING MOST SIG SNOW THROUGH THU
MORNING. HOWEVER, FOR MOST OF THE AREA, EXPECT “THE BIG SHOW” TO
BE WITH INITIAL SLUG OF WARM CONVEYOR BELT PCPN TONIGHT. 00Z/12
GFS FEATURES A NARROW STRIP OF NEGATIVE EPV AT H6-7 LATE
TONIGHT/ERY THU MORNING JUST SE OF RIC METRO (FGEN BAND ORIENTED
ALONG NORTH CWA BORDER). MODEL CROSS SECTIONS SHOW CONVECTIVE
PROCESSES APPEAR MORE SLANTWISE THAN UPRIGHT FOR TSSN (UPRIGHT
INSTABILITY BEING THE MORE IDEAL). STILL, NOT AT ALL OUT OF THE
QUESTION FOR A PERIOD OF THUNDER SNOW WITH THAT FGEN BAND LATE
THIS EVENING…AND HV ADDED HVY SNOW WORDING EARLY TONIGHT TO
CONVEY QUICK RAMP UP TO HVY PCPN COINCIDING WITH ONSET OF EVENING
RUSH HOUR.

TEMPERATURES/TIMING THE CHANGEOVER…
WHILE “BIG SHOW” WL COME THIS EVENING, BUT BIGGEST FORECAST
CHALLENGE COMES OVERNIGHT. PRECIPITATION CONTINUES OVERNIGHT AND
INTO THU AFTN. THANKS TO THE HIGH RETREATING OVER NORTHERN
NE…SYNOPTIC SETUP/CLIMO DON`T FAVOR COLD AIR REMAINING IN PLACE
AS LONG AS IT WOULD IF BETTER BLOCKING REGIME WERE IN PLACE. USED
A GFS/EC/SREF BLEND FOR QPF/THICKNESSES/TIMING. THIS BLEND IS A
HAIR WARMER THAN THE CMC…BUT A BIT COOLER THAN THE PRVS
FORECAST. EC/GFS BLEND WAS USED FOR SFC LOW TRACK, WHICH IS JUST A
BIT EAST OF WPC TRACK. QPF GENERALLY ~1″ NORTH TO AN INCH AND ONE
HALF ACROSS THE COASTAL ZONES.

THINKING IS FOR A PERIOD OF MODERATE TO HVY SNOW BTWN 00Z-06Z
ACROSS MOST OF THE FA NW OF A EMPORIA- WAKEFIELD- NEWPORT NEWS-
SALISBURY LINE. LOW PRES APPROACHES CAPE HAT AFTER 06Z…THICKNESSES
SUGGEST ENUF OF A WARM LAYER ALOFT TO INDICATE A CHANGEOVER TO A
MIXED BAG OF PCPN MAINLY ALONG AND E OF A I85-I95 LINE WITH MOST
AREAS E OF I95 GOING OVER TO ALL RAIN LATE. APPEARS NWRN MOST
COUNTYS STAY SNOW THRU THE EVENT WITH THE MOST ACCUMULATIONS
THERE. A TRANSITION OVER TO A MIXED BAG OF PCPN WITH AREAS E/SE OF
I95 GOING OVER TO RAIN. NEXT CONCERN IS FOR SOME FREEZING RAIN AND
SLEET… THUS SOME ICE ACCUMULATIONS AROUND A TENTH OR SO PSBL.
LOWS 25-30 WEST OF CHES BAY AND LWR MD ERN SHORE…RANGING TO
M-U30S SERN COASTAL AREAS.

AS TO SNOW ACCUMULATIONS…TYPICAL MID-ATLANTIC EVENT ACROSS THE
AKQ CWA. GRADIENT EXPECTED TO BE QUITE TIGHT. ACCUMULATIONS HIGHEST
ACROSS THE NW TIER OF THE WARNING AREA… WITH 10-12+” OF SNOW A
GOOD BET ALONG AND NORTH OF US 360 (CREWE/FVX ON NW). A PERIOD OF
SLEET/SNOW SHOULD ALLOW FOR SLIGHTLY LOWER ACCUMS ACROSS THE WEST
END WITH ACCUMS IN THE 6-10 RANGE. MORE MIXING (AND SOME FZRA)
SHOULD KEEP TRI-CITIES AREA IN 4-8 RANGE. 2-4 ACRS HAMPTON ROADS
(HENCE THE WINTER WX ADVY FOR WESTERN TIDEWATER). WHILE WE HV
SKIPPED WINTER WX ADVY FOR SOUTHERN TIDEWATER/COASTAL NE
NC…EXPECT A LIGHT SNOW/SLEET ACCUMULATION BEFORE CHANGEOVER TO
RA.

THURSDAY…
MIXED PCPN CONTS THURSDAY MORNING ACROSS THE AREA. CAA ON BACK SIDE
OF LOW COMBINED WITH A PRONOUNCED WRAP AROUND MOISTURE RESULTS IN
THE PCPN TURNING BACK TO SNOW THURSDAY AFTERNOON AS THICKNESSES
CRASH TOWARD THE COAST. ADDITIONAL LIGHT ACCUMULATIONS ARE LIKELY
DURING THIS PERIOD, ESPECIALLY OVER THE NORTHERN NECK/ERN SHORE.
HIGHS M-U30S EXCEPT NR 40 SERN COASTAL AREAS.

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