Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

031
FXUS61 KLWX 041054
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
554 AM EST THU FEB 4 2016

.SYNOPSIS...
A COLD FRONT WILL STALL OFF THE MID-ATLANTIC COAST TODAY. A WAVE OF
LOW PRESSURE WILL RIDE ALONG THE BOUNDARY...PASSING BY WELL TO OUR
SOUTH AND EAST THURSDAY NIGHT INTO FRIDAY. HIGH PRESSURE WILL RETURN
FOR SATURDAY. COASTAL LOW PRESSURE WILL PASS BY WELL TO OUR SOUTH
AND EAST SUNDAY. ANOTHER LOW PRESSURE SYSTEM MAY IMPACT THE AREA
EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 600 AM THURSDAY...COLD FRONT HAS CROSSED THROUGH MUCH OF THE
REGION AND WILL CONTINUE BRINGING DRYING AND COOLING CONDITIONS.
MUCH OF THE LOW CLOUDS...FOG...AND DRIZZLE HAVE DISSIPATED...WITH
ONLY SOME LOCALIZED AREAS OF FOG REMAINING OUT AHEAD OF THE FRONT.
SHOULD SEE FURTHER DISSIPATION OF THIS TOWARDS SUNRISE AS DRYING
WORKS ITS WAY IN. OTHERWISE FRONT SETTLES SOUTH AND EAST OF THE
REGION TODAY...LEAVING US WITH A MOSTLY DRY DAY AT LEAST INTO THE
FIRST HALF OF THE AFTERNOON...ALBEIT WITH A GOOD DEAL OF CLOUD
COVER. AS NORTHWEST FLOW DEVELOPS...MAY SEE SOME LIGHT UPSLOPE
SNOW SHOWERS ALONG THE ALLEGHENY FRONT...BUT NO ACCUMULATIONS
EXPECTED.

IN THE MID TO LATE AFTERNOON HOURS...AS WAVE OF LOW PRESSURE RIDES
UP THE LINGERING FRONTAL BOUNDARY TO OUR SOUTH...WILL SEE RAIN
SPREAD BACK NORTHWARD AND INTO PORTIONS OF OUR SOUTHEASTERN
ZONES...ESPECIALLY SOUTHERN MARYLAND.

HIGH TEMPERATURES WILL RANGE FROM THE UPPER 30S WELL NORTH AND
WEST TO MID 50S SOUTH AND EAST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
WAVE LOW WILL MOVE FROM OFF THE COAST OF THE CAROLINAS THIS
EVENING AND OUT TO SEA ON FRIDAY. EXPECTING STEADY RAIN TO BE
FALLING FOR THE FIRST HALF OF TONIGHT...BUT AS TEMPERATURES
COOL...ESPECIALLY IN ANY HEAVIER PRECIPITATION...WILL LIKELY SEE
PRECIP MIX WITH AND CHANGE TO A PERIOD OF SNOW BEFORE ENDING
FRIDAY MORNING. IS A MARGINAL SITUATION WITH BOUNDARY LAYER
TEMPERATURES IN THE 33 TO 36 DEGREE RANGE...BUT COULD SEE A WET
ACCUMULATION OF SNOW OF 0.5-1.5" ACROSS SOUTHERN
MARYLAND...ESPECIALLY ST. MARYS AND CALVERT COUNTIES...MAINLY
GRASSY SURFACES. COULD SEE SOME FLAKES AS FAR WEST AS I-95...BUT
NOT CURRENTLY EXPECTING ANY ACCUMULATION.

HIGH PRESSURE BUILDS IN ON FRIDAY...AND PERSISTS THROUGH SATURDAY.
BOTH NORTHERN STREAM AND SOUTHERN STREAM SYSTEMS MOVE TOWARDS THE
EAST COAST SATURDAY NIGHT...BUT WILL REMAIN UNPHASED WITH CLIPPER
STAYING TO OUR NORTH AND LOW PRESSURE REMAINING WELL TO OUR SOUTH
AND OFFSHORE.

HIGHS UPPER 30S TO MID 40S FRIDAY AND MID 40S TO NEAR 50F
SATURDAY. LOWS IN THE 20S TO LOW 30S...COLDEST FRIDAY NIGHT.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
COASTAL LOW PRESSURE WILL MOVE OUT TO SEA WELL OFF TO OUR SOUTH
AND EAST SUNDAY. SURFACE HIGH PRESSURE WILL REMAIN
OVERHEAD...BRINGING SEASONABLY CHILLY AND DRY CONDITIONS.

CONFIDENCE REMAINS HIGH FOR A HIGH AMPLITUDE PATTERN WITH A POTENT
UPPER-LEVEL TROUGH OVERHEAD MONDAY THROUGH WEDNESDAY...BUT THE
DETAILS AND TIMING OF THE SHORTWAVE ENERGY ARE HIGHLY UNCERTAIN
WHICH LEADS TO A LOW CONFIDENCE FORECAST.

LATEST GUIDANCE CONTINUES TO SUGGEST THAT COASTAL LOW PRESSURE MAY
DEVELOP MONDAY INTO TUESDAY...BUT THE LATEST TREND IS TO INDICATE
THAT IT MAY NOT INTENSIFY RAPIDLY ENOUGH TO AFFECT OUR AREA WITH A
SIGNIFICANT WINTER STORM. HOWEVER...GIVEN THE HIGH AMPLITUDE PATTERN
THIS IS STILL POSSIBLE AND IT WILL HAVE TO BE MONITORED OVER THE
NEXT SEVERAL DAYS.

THE LOW SHOULD PULL AWAY FROM THE AREA WEDNESDAY...BUT THE UPPER-
LEVEL TROUGH WILL REMAIN OVERHEAD. COLD CONDITIONS ARE EXPECTED AND
A FEW SNOW SHOWERS ARE POSSIBLE DUE TO THE UPPER-LEVEL TROUGH.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
MUCH OF THE IFR/LIFR CONDITIONS IN FOG...DRIZZLE...AND LOW CLOUDS
EARLY THIS MORNING HAVE DISSIPATED AS FRONTAL BOUNDARY CROSSED
REGION...AND ANY REMAINING WILL GRADUALLY IMPROVE AS THE MORNING
WEARS ON WITH VFR DEVELOPING AREA-WIDE. WILL ALSO SEE WINDS PICK
UP OUT OF THE NORTHWEST LATER THIS MORNING AND INTO THE AFTERNOON
WITH GUSTS 15-17 KNOTS DEVELOPING.

VFR CONDITIONS ARE THEN EXPECTED TO CONTINUE TONIGHT THROUGH
SATURDAY. THERE MAY BE A BRIEF PERIOD OF LIGHT SNOW/FLURRIES AT
DCA/BWI/MTN LATE TONIGHT...BUT NO SIGNIFICANT IMPACTS/REDUCTIONS
ARE CURRENTLY EXPECTED. WINDS BRIEFLY SLACKEN THIS EVENING BEFORE
RESTRENGTHENING OUT OF THE NORTHWEST AFTER MIDNIGHT TONIGHT AND ON
FRIDAY WITH GUSTS 15-20 KNOTS.

VFR CONDITIONS ARE LIKELY FOR SUNDAY. LOW PRESSURE MAY IMPACT THE
TERMINALS MONDAY INTO TUESDAY. DETAILS ARE UNCERTAIN AT THIS TIME.

&&

.MARINE...
FRONT CROSSING THE POTOMAC AND CHESAPEAKE NOW WITH NORTHWEST WINDS
PICKING UP BEHIND IT. THUS SMALL CRAFT ADVISORY IS IN EFFECT FOR
ALL WATERS INTO THE AFTERNOON HOURS. WINDS SLACKEN BRIEFLY LATE
THIS AFTERNOON AND EVENING...SO SCA ONLY FOR LOWER CHESAPEAKE BAY
AND LOWER POTOMAC. HOWEVER WINDS WILL INCREASE AGAIN LATER TONIGHT
AND ON FRIDAY...WITH SMALL CRAFT ADVISORY IN EFFECT FOR ALL WATERS
AGAIN. WIND GUSTS MAY APPROACH GALE FORCE FIRST HALF OF FRIDAY.
WINDS WILL THEN WEAKEN AND FALL BELOW SCA CRITERIA FRIDAY NIGHT
AND SATURDAY.

COASTAL LOW PRESSURE WILL PASS BY WELL TO THE SOUTH AND
EAST OF THE WATERS SUNDAY INTO SUNDAY NIGHT. THE GRADIENT MAY BE
STRONG ENOUGH FOR WINDS TO APPROACH SCA CRITERIA OVER PORTIONS OF
THE WATERS.

LOW PRESSURE MAY IMPACT THE WATERS MONDAY INTO TUESDAY. GUSTY WINDS
ARE POSSIBLE DURING THIS TIME...BUT DETAILS REMAIN HIGHLY UNCERTAIN.
THE LOW WILL MOVE AWAY FROM THE AREA WEDNESDAY AS IT INTENSIFIES.
GUSTY NORTHWEST WINDS ARE POSSIBLE.

&&

.HYDROLOGY...
RAIN HAS ENDED ACROSS THE REGION. RAINFALL AMOUNTS RANGED FROM A
HALF INCH TO INCH ACROSS THE POTOMAC...SHENANDOAH AND RAPPAHANNOCK
BASINS WITH ISOLATED AMOUNTS UP TO AN INCH AND A QUARTER. THIS
COUPLED WITH TEMPERATURES AND DEWPOINTS IN THE 40S/50S ALLOWED
MUCH OF THE REMAINING SNOW TO MELT AND FURTHER SATURATE THE SOIL.

SMALL STREAMS AND CREEKS ARE MOSTLY ON THE DECLINE EARLY THIS
MORNING...ALTHOUGH LARGER RIVERS CONTINUE TO RISE.

RIVER FLOOD WARNINGS ARE CURRENTLY IN EFFECT FOR
CACAPON...OPEQUON...MONACACY...GOOSE CREEK...POTOMAC FROM POINT
OF ROCKS TO EDWARDS FERRY...AND SHENANDOAH AT MILLVILLE FOR
FLOODING TODAY. A RIVER FLOOD WATCH CONTINUES FOR POTOMAC RIVER
INCLUDING HARPERS FERRY AND LITTLE FALLS. PLEASE SEE FLOOD WATCH
AND FLOOD WARNING PRODUCTS FOR MORE INFORMATION.

&&

.TIDES/COASTAL FLOODING...
AN OFFSHORE FLOW WILL DEVELOP EARLY THIS MORNING AND THIS WILL
CAUSE TIDAL ANOMALIES TO DECREASE FOR MOST AREAS.

WILL HAVE TO WATCH FOR FRESHWATER INUNDATION ALONG THE UPPER TIDAL
POTOMAC RIVER...PARTICULARLY NEAR GEORGETOWN. WATER LEVELS MAY
APPROACH MODERATE FLOODING THRESHOLDS. A COASTAL FLOOD WATCH IS IN
EFFECT. THE BEST CHANCE FOR MODERATE FLOODING TO OCCUR WILL BE
AROUND HIGH TIDE LATE TONIGHT...AND AGAIN AROUND HIGH TIDE LATER
FRIDAY AFTERNOON INTO FRIDAY EVENING.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH
     FRIDAY EVENING FOR DCZ001.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     ANZ530>533-535-536-538>542.
     SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST FRIDAY
     FOR ANZ530>533-535-536-538>542.
     SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR ANZ534-537-543.

&&

$$
SYNOPSIS...BJL/MM
NEAR TERM...MM
SHORT TERM...MM
LONG TERM...BJL
AVIATION...BJL/MM
MARINE...BJL/MM
HYDROLOGY...JE/BJL/MM
TIDES/COASTAL FLOODING...BJL



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.