Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 050121
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
821 PM EST WED MAR 4 2015

.SYNOPSIS...
A COLD FRONT SLOWLY CROSSES THE REGION THROUGH TONIGHT. THE FRONT
WILL STALL OVER NORTH CAROLINA ON THURSDAY...WITH A WAVE OF LOW
PRESSURE MOVING ALONG THE FRONT THURSDAY AFTERNOON AND NIGHT. THIS
WILL BRING ANOTHER ROUND OF WINTRY WEATHER TO THE AREA...FOLLOWED
BY COLD AND DRY CONDITIONS BY FRIDAY. GRADUALLY MODERATING...MILDER
TEMPERATURES ARE EXPECTED LATE IN THE WEEKEND INTO NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
MADE SOME UPDATES TO POPS THIS EVENING...MAINLY TO SLOW THE PROGRESSION
SOUTH OF THE HIGHER POPS TO KEEP ALL BUT NORTHERNMOST PORTIONS OF
THE CWA DRY FOR THE NEXT FEW HRS. THIS BASED ON CURRENT RADAR
TRENDS SHOWING PRECIP TENDING TO LIFT NORTH THROUGH 03Z WITH FIRST
WAVE OF SFC LOW PRESSURE TRACKING ENE ACRS THE CWA (WITH PRECIP
STAYING NORTH OF THE SFC LOW). THE PRECIP CURRENTLY OVER WRN VA/WV
LOOKS POISED TO OVERSPREAD NORTHERN AREAS AFTER 03Z...AND SHIFT
SOUTH INTO CENTRAL VA BETWEEN 04-06Z...THIS AS MAIN SFC LOW OVER
THE NC/SC PIEDMONT BEGINS TO DEEPEN. ALSO ADDED FOG ACRS THE NORTH
WHERE OBS ARE INDICATING VSBYS FROM 2SM DOWN TO 1/4SM IN SPOTS.
EXPECT VSBYS TO IMPROVE SOMEWHAT LATER THIS EVENING AS WINDS
INCREASE AND WIDESPREAD RAIN MOVES IN FROM THE NORTH (COULD SEE
SOME LOCALLY DENSE FOG PUSH SOUTH INTO CENTRAL VA FOR A FEW HRS AS
WELL).

PREV DISCUSSION...
LATEST WX ANALYSIS FEATURES A WELL DEFINED FRONTAL BOUNDARY OVER
THE MID SOUTH/LWR OHIO VALLEY THAT SEEMS TO HAVE PHASED WITH
ANOTHER, MORE DIFFUSE BOUNDARY STRETCHING FROM THE WV PANHANDLE
INTO THE INTERIOR NORTHEAST. WEAK FORCING HAS GENERALLY KEPT
PRECIP AT BAY THIS AFTERNOON. WHERE CAD WEDGE WAS ABLE TO BE FULLY
ERODED ACROSS THE SOUTHERN CWA, TEMPS HAVE CLIMBED NICELY AS
EXPECTED INTO THE U60S/L70S. POPS REMAIN 30-40% FOR SOME SPOTTY
SHRAS ACROSS THE NORTH THROUGH EARLY EVENING, THOUGH WILL DEPICT
GRADUAL RAMP UP OF POPS IN THE GRIDS THIS EVENING AND OVERNIGHT
ACROSS THE NORTH AS FRONT TO THE NORTHWEST DROPS ACROSS THE AREA
SLOWLY THROUGH LATE TONIGHT.

MODELS REMAIN IN GOOD AGREEMENT WITH RESPECT TO FRONTAL TIMING,
AND HAVE USED A GFS/NAM BLENDED SOLUTION FOR TIMING IN THE NEAR
TERM. STILL EXPECTING INITIAL WAVE OF LOW PRESSURE TO MOVE SW TO
NE ALONG THE FRONT AND TRACKS ACROSS THE CAROLINAS LATE TONIGHT
INTO THURSDAY. MUCH COLDER AIR ARRIVES BEHIND THE FRONT WITH MOST
OF THE AREA FALLING INTO THE UPPER 20S/LOW 30S BY THU AFTN. BUFR
FORECAST SOUNDINGS CONTINUE TO DEPICT DRY AIR LINGERING BETWEEN
600-400MB TONIGHT...SO ANY PCPN (IN THE FORM OF -RA) OVERNIGHT
WILL BE LIGHT. A STRONG ANTI-CYCLONIC JET IN PLACE FROM THE MID
MISS VLY THROUGH ATLANTIC CANADA WILL TRANSLATE EWD THROUGH THE
DAY THU AS A STRONG TROUGH DIGS ACROSS THE UPPER MIDWEST AND GREAT
LAKES BY LATER THU MORNING INTO THU AFTERNOON. IT IS AT THIS TIME
THAT DEEPER MOISTURE WILL ARRIVE AND RRQ FORCING WILL BE
IDEALIZED, AS STRONG PV ANOMALY RIDES ACROSS THE AREA THU THROUGH
THU NIGHT, TRIGGERING THE ONSET OF WINTRY PCPN FROM NW-SE ACROSS
THE AREA.

CRITICAL H85-7 THICKNESS VALUES (SUB 1540M) ARE NOT REALIZED UNTIL
LATE IN THE AFTN THU INTO THU NIGHT OVER NORTHERN HALF OF THE AREA.
HOWEVER...BY THIS TIME THE STRONGEST UVM WILL BE EXITING THE
COAST. OVERALL, UTILIZING ROEBBER SLR FORECASTING TOOL ALONG WITH
LOCAL THICKNESS CHART, FORECAST SLR VALUES WILL BE QUITE LOW FOR
MUCH OF THE DAY (PERHAPS AS LOW AS 4:1-8:1). THIS MAKES SENSE GIVEN
THAT THERE WILL BE A PROLONGED PERIOD OF SLEET (WHICH WILL EAT
INTO SNOWFALL TOTALS)...AND THAT MID-LEVEL THICKNESSES WILL BE
`WARM` DURING THE STRONGEST FORCING IN THE EARLY TO MID AFTERNOON
HOURS. BASED ON ALL OF THE ABOVE, HAVE CONTINUED WITH A STRIPE OF
3-5" OF WET SNOW/SLEET ALONG A LINE FROM PALMYRA, VA TO
TAPPAHANNOCK AND SALISBURY, MD. THIS IS BORDERED BY A BAND OF 2-3"
FOR OTHER PORTIONS OF THE NW PIEDMONT...NRN NECK...NORTHERN RIC
SUBURBS AND REMAINDER OF THE LOWER MD EASTERN SHORE. CURRENTLY
1-2" OF SLEET/SNOW IS FORECAST FROM THE SOUTHERN SECTIONS OF THE
RIC METRO /TRI-CITIES DOWN THROUGH HAMPTON ROADS...WITH 1" OR LESS
ALONG THE HIGHWAY 58 CORRIDOR OVER CENTRAL VA INTO THE PIEDMONT.
THIS TRANSLATES TO WINTER STORM WARNINGS BEING HOISTED ALONG OUR
NORTHERN TIER OF COUNTIES, WITH A TIER OF WINTER WEATHER
ADVISORIES FOR THE RIC METRO AREA, THE PIEDMONT AND THE MIDDLE
PENINSULA MAINLY ALONG AND NORTH OF A FARMVILLE TO PETERSBURG AND
WILLIAMSBURG LINE.

CONFIDENCE IS NOT HIGH ENOUGH TO CONTINUE ADVISORIES FARTHER SOUTH
INTO SOUTH CENTRAL VA COUNTIES. GIVEN THAT ANY IMPACTS WOULD COME
THURSDAY NIGHT IN THIS AREA, HAVE THEREFORE CONTINUED HWO MENTION
GIVEN EXPECTATION OF SUB-ADVISORY CONDITIONS.

WINTRY PCPN SHOULD TAPER OFF THU EVENING...AS TOP DOWN DRYING
ENSUES W/DRIER AIR ARRIVING FROM THE NW DURING THE LATE EVENING.
COULD SEE A BRIEF PERIOD OF FREEZING DRIZZLE LATE THU EVENING,
HENCE DRAGGING ALL WINTER HEADLINES THROUGH MIDNIGHT THU NGT/FRI
MORNING.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
HIGH PRESSURE/FAIR WEATHER TO PREVAIL DURING THE SHORT TERM.

SHORTWAVE EXITS THE NE COAST FRI MORNING WITH CONFLUENCE ALOFT OVER
THE MID-ATLANTIC. THIS WILL ALLOW STRONG 1030+MB ARCTIC HIGH
PRESSURE TO CENTER OVER THE REGION FRI. COLD FRONT LOCATES
OFFSHORE...EXTENDING SWWD INTO THE NRN GULF. BEST MOISTURE GETS
SHUNTED OFFSHORE IN INCREASING WLY FLOW ALOFT. THE RESULT WILL BE
DRY CONDITIONS...BUT WELL BELOW NORMAL TEMPERATURES. H85 TEMPS ~-8C
AND LOW LEVEL THICKNESSES YIELD TEMPS IN THE LOW-MID 30S...POSSIBLY
UPPER INTERIOR MD ERN SHORE. THE NEXT NRN STREAM SHORTWAVE CROSSES
THE REGION FRI NIGHT...RESULTING IN LITTLE MORE THAN PARTLY CLOUDY
SKIES. COLD FRI NIGHT WITH LOW GENERALLY MID TEENS TO AROUND 20.
ZONAL FLOW DEVELOPS SUN AS HIGH PRESSURE REMAINS OVER THE REGION.
SWLY RETURN FLOW COMMENCES...RESULTING IN MODERATING LOW LEVEL
THICKNESSES AND TEMPS. THICKNESSES YIELD TEMPS IN THE LOW-MID 50S
INLAND SUN...BUT GUIDANCE RUNNING IN THE MID-UPPER 40S. TRENDED
TOWARD THICKNESSES...WITH HIGHS IN THE UPPER 40S-LOW 50S INLAND AND
LOW TO MID 40S NEAR THE COAST...UNDER MOSTLY SUNNY TO PARTLY CLOUDY
SKIES.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
GOING CLOSE TO THE 12Z GFS/CMC IN THE EXTENDED PERIOD. WILL MAINTAIN
DRY WX FM SAT NGT THRU AT LEAST MON NGT AT THIS TIME..AS HI PRES
WILL BE OVR THE AREA. THERE IS THEN A HINT OF LO PRES MOVNG NE OUT
OF THE GULF AND ACRS THE REGION TUE THRU WED. FOR NOW...JUST HAVE
SLGT CHC OF RAIN DURING THIS TIME. TEMPS WILL BE CLOSER TO
SEASONABLE RDGS THRU THE PERIOD. MIN TEMPS WILL RANGE FM THE UPR
20S TO UPR 30S...AND MAX TEMPS WILL RANGE FM THE UPR 40S TO UPR
50S...MAYBE INTO THE 60S ON WED.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
AS OF 01Z...COLD FRONT IS STILL NORTH OF THE AREA WITH VARIOUS
BOUNDARIES SOUTH OF THE FRONT CAUSING VARIABLE WINDS AND FLIGHT
CONDITIONS. LIFR CONDS AT SBY AND PHF ARE EXPECTED TO BE
INTERMITTENT UNTIL THE COLD FRONT MOVES FROM NORTH TO SOUTH ACRS THE
TAF SITES DURING THE EARLY MORNING HOURS. FOLLOWING THE FRONTAL
PASSAGE...MVFR/IFR CIGS BECOME SOLIDLY IFR/LIFR TOWARD MORNING AS
RAIN DEVELOPS. RAIN MIXES WITH FREEZING RAIN AND SLEET FOR A PERIOD
OF TIME BEFORE TRANSITIONING TO SNOW WITH THE CHANGE OCCURRING FROM
NORTH TO SOUTH DURING THE DAY THURSDAY. TWO TO FOUR INCH SNOW
ACCUMULATIONS ARE EXPECTED AT RIC AND SBY WITH AN INCH OR LESS AT
THE SE TAF SITES. WINDS WILL BE GUSTY FROM THE NORTH MUCH OF THE
DAY.

OUTLOOK...PCPN MOVES OFF TO THE EAST THURSDAY EVENING AND VFR
RETURNS. GOOD WEATHER IS EXPECTED FRIDAY INTO EARLY NEXT WEEK.

&&

.MARINE...
A COLD FRNT WILL DROP ACRS THE WTRS LATER THIS EVENG INTO THU
MORNG...AS SEVERAL WEAK WAVES OF LO PRES MOVE NE ALNG THE BNDRY.
AS THE FRNT PUSHES SE OF THE AREA TNGT...SCA CONDS WILL COMMENCE
OVR THE WTRS. THESE CONDS WILL CONTINUE THRU FRI MORNG AND INTO
THE AFTN FOR THE CSTL WTRS. WINDS MAY COME CLOSE TO GALE FORCE
OVR SRN CSTL WTRS...BUT CONFIDENCE IS STILL NOT HI ENUF TO ISSUE
A GALE WARNG ATTM. ALSO KEPT ALL RIVER ZNS EXCEPT THE LWR JAMES
OUT OF THE ADVSRY FOR NOW...BUT WILL CONTINUE TO MONITOR. WAVES
OVER THE CHES BAY WILL BLD TO 3-5 FT...WITH SEAS OVER CSTL WTRS
BLDNG TO 6-8 FT. SFC HI PRES THEN BLDS IN FOR FRI INTO THE
WEEKEND LEADING TO IMPROVING MARINE CONDS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING FROM 6 AM THURSDAY TO MIDNIGHT EST
     THURSDAY NIGHT FOR MDZ021>025.
NC...NONE.
VA...WINTER WEATHER ADVISORY FROM 6 AM THURSDAY TO MIDNIGHT EST
     THURSDAY NIGHT FOR VAZ060>062-067>073-077-078-080>086-090-
     099.
     WINTER STORM WARNING FROM 6 AM THURSDAY TO MIDNIGHT EST
     THURSDAY NIGHT FOR VAZ048-049-063-064-074>076.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST FRIDAY FOR ANZ650-652-654.
     SMALL CRAFT ADVISORY UNTIL 4 PM EST FRIDAY FOR ANZ656-658.
     SMALL CRAFT ADVISORY FROM 4 AM THURSDAY TO 10 AM EST FRIDAY
     FOR ANZ630>632-634.
     SMALL CRAFT ADVISORY FROM 7 AM THURSDAY TO 10 AM EST FRIDAY
     FOR ANZ633-638.

&&

$$
SYNOPSIS...MAM
NEAR TERM...AJZ/LKB/MAM
SHORT TERM...SAM
LONG TERM...SAM/TMG
AVIATION...SAM
MARINE...TMG





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