Area Forecast Discussion
Issued by NWS Sterling, VA

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633
FXUS61 KLWX 140202
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
902 PM EST SAT FEB 13 2016

.SYNOPSIS...
ARCTIC HIGH PRESSURE WILL BUILD THROUGH EARLY SUNDAY THEN MOVE
OFFSHORE SUNDAY NIGHT. LOW PRESSURE WILL MOVE ACROSS THE AREA
TUESDAY AND AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH TUESDAY
NIGHT. HIGH PRESSURE RETURNS FOR MIDDLE TO LATTER PART OF NEXT
WEEK.

&&

.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
GOING FORECAST IS IN GOOD SHAPE THIS EVENING. GUSTY WINDS WILL
GRADUALLY SLACKEN OVERNIGHT AS HIGH PRESSURE SLOWLY TRANSLATES
EASTWARD OVER THE REGION BY SUNDAY MORNING. VERY COLD CONDITIONS
WILL PERSIST WITH MIN TEMPS RANGING FROM BELOW ZERO IN THE
MOUNTAINS TO THE SINGLE DIGITS TO AROUND 10F ACROSS MOST OTHER
LOCATIONS. LOW WIND CHILLS WILL PERSIST WITH WIND CHILL ADVISORIES
STILL IN EFFECT FOR MOST AREAS TONIGHT INTO SUNDAY MORNING AND A
WIND CHILL WARNING FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY
FRONT.

&&

.SHORT TERM /7 AM SUNDAY MORNING THROUGH TUESDAY/...
ARCTIC HIGH PRESSURE OVERHEAD SUNDAY MORNING WILL MOVE OFF TO THE
EAST LATER SUNDAY THROUGH SUNDAY NIGHT. BITTERLY COLD CONDITIONS
WILL PERSIST...BUT WINDS WILL MUCH LIGHTER COMPARED TO SATURDAY.

THE HIGH WILL CONTINUE TO MOVE OUT INTO THE ATLANTIC SUNDAY NIGHT
THROUGH TUESDAY WHILE A LONGWAVE UPPER-LEVEL TROUGH BUILDS TOWARD
THE REGION FROM MIDWEST. SHORTWAVE ENERGY WILL ROTATE AROUND THE
TROUGH...CAUSING LOW PRESSURE TO DEVELOP OVER THE GULF COAST
STATES MONDAY BEFORE TRACKING THROUGH THE MID-ATLANTIC LATER
MONDAY NIGHT INTO TUESDAY. PLENTY OF WARM AND MOIST AIR WILL
OVERRUN THE ARCTIC AIR IN PLACE...CAUSING SNOW TO BREAK OUT LATE
SUNDAY NIGHT INTO MONDAY MORNING. SNOW WILL LIKELY CONTINUE
THROUGH MIDDAY MONDAY BEFORE CHANGING TO A WINTRY MIX AS WARMER
AIR WORKS IN ALOFT. WARMER AIR WILL CONTINUE TO WORK ITS WAY INTO
THE AREA MONDAY NIGHT INTO TUESDAY...CAUSING PRECIPITATION TO
GRADUALLY CHANGE TO RAIN EAST OF THE BLUE RIDGE. HOWEVER...POCKETS
OF FREEZING RAIN MAY LINGER FOR LOCATIONS WEST OF THE BLUE RIDGE
MOUNTAINS...AND TEMP PROFILES SUGGEST THE PTYPE MAY BE SNOW ALONG
THE ALLEGHENY FRONT.

DETAILS ON THE TIMING OF THE CHANGEOVER ARE UNCERTAIN AT THIS
TIME...BUT THERE WILL BE AN ACCUMULATING SNOW OF SEVERAL INCHES
AND ICE ACCUMULATION FROM FREEZING RAIN AS WELL. A WINTER STORM
WATCH IS IN EFFECT FOR MOST LOCATIONS NORTH AND WEST OF INTERSTATE
95. FOR LOCATIONS ALONG AND EAST OF INTERSTATE 95...ACCUMULATING
SNOW AND ICE IS EXPECTED BUT CONFIDENCE AMOUNTS REACHING REACHING
WATCH CRITERIA ARE LOW SO A HEADLINE HAS NOT BEEN ISSUED AT THIS
TIME.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AN UPPER LEVEL DISTURBANCE WILL MOVE EAST ALONG THE OHIO VALLEY
TOWARD THE MID-ATLANTIC COAST TUESDAY NIGHT. THIS DISTURBANCE COULD
BRING AN INCH OR TWO OF SNOW TO PARTS OF THE REGION.

ADDITIONAL WEAKER UPPER LEVEL ENERGY WILL MOVE THROUGHOUT THE MAIN
UPPER LEVEL TROUGH WEDNESDAY AND WEDNESDAY NIGHT. THIS ENERGY COULD
GENERATE A SLIGHT CHANCE OF A FEW LINGERING SNOW SHOWERS IN PARTS OF
THE REGION WITH BETTER EMPHASIS ON ACCUMULATING SNOW IN THE POTOMAC
HIGHLANDS.

ONCE THE MAIN UPPER LEVEL TROUGH OF LOW PRESSURE SLIDES OFFSHORE THE
EAST COAST THURSDAY MORNING...A BROAD AREA OF HIGH PRESSURE WILL
MOVE IN FROM THE WEST AND DOMINATE THE REGION THURSDAY THROUGH
FRIDAY. A REINFORCING SHOT OF COLD AIR WILL BE USHERED IN BY THIS
RIDGE OF HIGH PRESSURE.

BY FRIDAY NIGHT...THIS AREA OF HIGH PRESSURE WILL PUSH OFFSHORE TO
ALLOW FOR A LIGHT TO MODERATE SOUTHWEST FLOW TO DEVELOP ACROSS THE
REGION. AT THE SAME TIME...A COLD FRONT WILL DRAG ALONG THE LOWER
GREAT LAKES AND OHIO VALLEY FROM A STORM SYSTEM OVER EASTERN CANADA.

ON SATURDAY...THIS COLD FRONT WILL MOVE ACROSS THE MID-ATLANTIC
REGION AND BRING A CHANCE FOR SOME RAIN SHOWERS. THERE ARE LARGE
DISCREPANCIES ON THE STRENGTH AND LOCATION OF THE MAIN UPPER LEVEL
TROUGH OF LOW PRESSURE THAT WILL BE RESPONSIBLE FOR PUSHING THE
SURFACE COLD FRONT THROUGH THE REGION. THE GFS MODEL IS STRONGER AND
FASTER WITH THE COLD FRONT THAN THE EUROPEAN MODEL AT THIS TIME.
TIMING ON PRECIPITATION SATURDAY COULD COINCIDE WITH LOW
TEMPERATURES BELOW FREEZING TO PRODUCE SNOW AT THE ONSET. AS OF
NOW...WE HAVE A CHANCE FOR SOME RAIN SHOWERS.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
GUSTY NORTHWEST WINDS WILL SLOWLY WEAKEN OVERNIGHT...WITH LIGHTER
FLOW ON SUNDAY AS HIGH PRESSURE MOVES OVERHEAD. VFR CONDITIONS
WILL PREVAIL THROUGH SUNDAY EVENING. SNOW WILL OVERSPREAD THE
TERMINALS LATE SUNDAY NIGHT INTO MONDAY BEFORE CHANGING TO A
WINTRY MIX AND EVENTUALLY RAIN MONDAY NIGHT INTO TUESDAY.
IFR/SUBIFR CONDITIONS ARE EXPECTED DURING THIS TIME. CONDITIONS
MAY IMPROVE LATER TUESDAY AS LOW PRESSURE MOVES AWAY FROM THE
TERMINALS.

IFR OR LIFR CONDITIONS ARE POSSIBLE AT ANY OR ALL TERMINALS WITH
SNOW SHOWERS TUESDAY NIGHT. WINDS WEST AROUND 5 KNOTS.

MVFR OR BRIEF IFR CONDITIONS ARE POSSIBLE AT MRB...CHO...OR IAD
TERMINALS WITH LINGERING SNOW SHOWERS WEDNESDAY. ELSEWHERE SHOULD
HAVE VFR CONDITIONS. WINDS WEST-NORTHWEST AT 5 TO 10 KNOTS GUSTS 15
KNOTS.

&&

.MARINE...
GUSTY NORTHWEST WINDS WILL GRADUALLY SLACKEN TONIGHT INTO SUNDAY.
A GALE WARNING REMAINS IN EFFECT FOR THE WATERS THROUGH
TONIGHT...BUT IT MAY BE ABLE TO BE CANCELLED EARLIER...ESPECIALLY
ACROSS THE UPPER TIDAL POTOMAC RIVER AND NORTHERN CHESAPEAKE BAY.

HIGH PRESSURE WILL BUILD OVER THE WATERS SUNDAY. A SMALL CRAFT
ADVISORY IS STILL IN EFFECT...BUT WINDS WILL CONTINUE TO DIMINISH
INTO SUNDAY NIGHT. LOW PRESSURE WILL LIKELY IMPACT THE WATERS
LATER MONDAY INTO TUESDAY.

NO MARINE HAZARDS EXPECTED TUESDAY NIGHT AND WEDNESDAY.

&&

.TIDES/COASTAL FLOODING...
GUSTY NORTHWEST WINDS THROUGH TONIGHT WILL CAUSE TIDAL ANOMALIES
TO APPROACH 2 FEET BELOW THE ASTRONOMICAL NORMS. THE FLOW WILL
WEAKEN SUNDAY AND WATER LEVELS WILL RETURN CLOSER TO NORMAL.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR DCZ001.
MD...WIND CHILL WARNING UNTIL 9 AM EST SUNDAY FOR MDZ501.
     WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR MDZ003>006-011-
     013-014-016>018-502>508.
     WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH TUESDAY
     MORNING FOR MDZ003>005-501>505.
VA...WIND CHILL WARNING UNTIL 9 AM EST SUNDAY FOR VAZ503.
     WINTER STORM WATCH FROM SUNDAY EVENING THROUGH TUESDAY MORNING
     FOR VAZ025>027-029-030-036-037-503-504-507-508.
     WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR VAZ025>031-
     036>040-050>057-501-502-504>508.
     WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH TUESDAY
     MORNING FOR VAZ028-031-038>040-050>053-055-056-501-502-
     505-506.
WV...WIND CHILL WARNING UNTIL 9 AM EST SUNDAY FOR WVZ501-503-505.
     WINTER STORM WATCH FROM SUNDAY EVENING THROUGH TUESDAY MORNING
     FOR WVZ055-501-502-505-506.
     WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR WVZ050>053-055-
     502-504-506.
     WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH TUESDAY
     MORNING FOR WVZ050>053-503-504.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 1 PM EST SUNDAY FOR
     ANZ530>543.
     FREEZING SPRAY ADVISORY UNTIL 1 PM EST SUNDAY FOR ANZ530>543.
     GALE WARNING UNTIL 6 AM EST SUNDAY FOR ANZ530>543.

&&

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



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