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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 150207 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1007 PM EDT MON APR 14 2014 .SYNOPSIS...
-- Changed Discussion --
A COLD FRONT EXTENDING FROM SOUTHERN QUEBEC CANADA...ACROSS THE EASTERN GREAT LAKES AND EASTERN OHIO VALLEY...AND INTO THE TENNESSEE VALLEY WILL PUSH ACROSS THE APPALACHIAN MOUNTAINS OVERNIGHT. THIS FRONT WILL PUSH ACROSS OUR REGION DURING THE DAY ON TUESDAY. HIGH PRESSURE WILL BUILD EAST INTO THE NORTHERN MID- ATLANTIC WEDNESDAY AND REMAIN OVER THE AREA THROUGH FRIDAY. LOW PRESSURE MAY IMPACT THE REGION ON SATURDAY.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TUESDAY/...
-- Changed Discussion --
EVEN AT THIS HOUR IN THE EVENING...TEMPERATURES ARE IN THE UPPER 60S TO LOWER 70S ACROSS MUCH OF THE REGION AHEAD OF A STRONG COLD FRONT. DEWPOINT TEMPERATURES HAVE INCREASED IN MANY LOCATIONS INTO THE LOWER TO MIDDLE 50S INDICATING GOOD LOW LEVEL MOISTURE. DON`T ANTICIPATE MUCH OF A RAPID CHANGE IN EITHER OVERNIGHT DUE TO WARM ADVECTION OF BOTH ELEMENTS IN BALANCE WITH NOCTURNAL COOLING. TEMPERATURES AND DEWPOINT TEMPERATURES MAY RISE A FEW DEGREES AT BEST. WE ARE THINKING CHANCE POPS IN THE NORTHERN AND EASTERN PORTIONS OF THE REGION THE REMAINDER OF THIS EVENING AS A FEW RAIN SHOWERS MOVE ACROSS THE REGION. RAIN AMOUNTS LESS THAN ONE TENTH OF AN INCH. LIKELY POPS ACROSS THE CENTRAL SHENANDOAH VALLEY AND VIRGINIA PIEDMONT THIS EVENING AND OVERNIGHT WILL LEAD TO ABOUT ONE QUARTER OF AN INCH OF RAIN IN PLACES. ALTHOUGH SOUTHERLY WINDS HAVE DECREASED DURING THE PAST FEW HOURS...EXPECT SOUTHERLY WINDS TO INCREASE ONCE AGAIN LATER IN THE OVERNIGHT HOURS INTO TUESDAY MORNING AHEAD OF THE COLD FRONT WITH ADDITIONAL DAYTIME HEATING AND MIXING. ADDITIONAL RAIN SHOWERS AND DEVELOPING THUNDERSTORMS WILL OCCUR AHEAD OF THE MAIN COLD FRONT FROM WEST TO EAST TUESDAY MORNING THROUGH MID AFTERNOON. THE COLD FRONT IS EXPECTED TO CROSS THE POTOMAC HIGHLANDS AROUND 12Z...REACH THE I-95 CORRIDOR AROUND 18Z...BEFORE MOVING EAST OF THE CHESAPEAKE BAY AND ALONG THE DELMARVA EAST COAST BY 00Z WEDNESDAY. ALONG AND AHEAD OF THIS FRONT...GUSTY RAIN SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP. RAIN AMOUNTS DURING THE DAY TUESDAY WILL AVERAGE ONE HALF TO ONE INCH WITH ISOLATED HIGHER AMOUNTS IN SHOWERS AND THUNDERSTORMS. DESPITE A LOT OF RAIN WITH THIS ACTIVITY...THE MAIN THREAT FROM THESE SHOWERS AND STORMS WILL BE GUSTY WINDS...GUSTING IN EXCESS OF 50 MPH. SOUTHERLY WINDS WILL BECOME GUSTY EVEN BEFORE THE HEAVIEST RAIN AND THUNDERSTORMS DEVELOP. SOUTHERLY WINDS WILL GUST 20 TO 30 MPH AHEAD OF THIS ACTIVITY AND ITS COLD FRONT. ONCE THE SURFACE COLD FRONT PASSES AND ITS UPPER LEVEL SUPPORT SWINGS ACROSS THE REGION...NORTHWEST WINDS WILL BECOME STRONG AND GUSTING 30 TO 40 MPH FREQUENTLY LATE TUESDAY. THESE STRONG WINDS WILL USHER IN UNSEASONABLY CHILLY AIR.
-- End Changed Discussion --
&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... COLD FRONT MOVES OFFSHORE THROUGH THE EARLY EVENING HOURS ON TUESDAY. STRONG COLD AIR ADVECTION CONTINUES TO SUPPORT FALLING TEMPERATURES. FOLLOWED SREFS FOR POPS DECREASING FROM WEST TO EAST THROUGH EARLY EVENING. IF COLD AIR CAN CATCH UP TO THE BACK EDGE OF PRECIP QUICKLY ENOUGH...A FEW WET SNOWFLAKES COULD OCCUR BUT THE BULK OF THE PRECIP WILL END AS RAIN. FOCUS THEN TURNS TO THE COLD AIR. WITH COLD ADVECTION...MOMENTUM TRANSFER WILL KEEP GUSTY NORTHWEST WINDS GOING INTO THE NIGHT. BUT ITS THESE NORTHWEST WINDS THAT ARE BRINGING IN A MUCH COLDER AIR MASS AND DESPITE THE WIND TEMPERATURES HAVE THE POTENTIAL TO DROP BELOW FREEZING BY DAYBREAK ESPECIALLY IN THE SUBURBS. THE GROWING SEASON WILL BEGIN APRIL 15TH EAST OF THE BLUE RIDGE...WHICH MEANS THESE AREAS WILL BE CANDIDATES FOR FROST/FREEZE HEADLINES. CONSIDERING FORECAST MINIMA...WILL BE ISSUING A FREEZE WATCH FOR TUESDAY NIGHT/WEDNESDAY MORNING. HIGH PRESSURE BUILDS IN FOR WEDNESDAY. SUNSHINE WILL RETURN BUT MAXIMA MAY STRUGGLE TO REACH 50. HIGH PRESSURE WEDNESDAY NIGHT WILL ALSO PAVE THE WAY FOR ANOTHER COLD NIGHT WITH RADIATIONAL COOLING IN PLAY. ADDITIONAL FREEZE HEADLINES MAY BECOME NECESSARY WEDNESDAY NIGHT INTO THURSDAY MORNING. MODERATING TREND SHOULD BEGIN THURSDAY WITH HIGH PRESSURE MOVING OFF THE COAST. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... SURFACE HIGH PRESSURE WILL DEPART INTO THE NORTH ATLANTIC THURSDAY NIGHT...LEAVING BEHIND A SURFACE RIDGE AXIS WEDGED AGAINST THE EASTERN SLOPES OF THE APPALACHIANS. THIS WILL RESULT IN A CONTINUED ONSHORE FLOW THROUGH FRIDAY. AN UPPER-LEVEL TROUGH AND SURFACE LOW PRESSURE APPROACH THE AREA FROM THE WEST LATE FRIDAY NIGHT INTO SATURDAY. THE LATEST GUIDANCE SHOWS A WIDE SPREAD IN THE DEPTH OF THE APPROACHING TROUGH AND STRENGTH OF LOW PRESSURE AT THE SURFACE. RAIN IS LIKELY FOR AT LEAST PART OF THE AREA SATURDAY...BUT THERE IS A MODERATE TO HIGH LEVEL OF UNCERTAINTY IN INTENSITY/COVERAGE. WEAK RIDGING AND MILDER WEATHER LOOKS TO BUILD INTO THE AREA LATE IN THE WEEKEND INTO EARLY NEXT WEEK. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
VFR CONDITIONS EXPECTED AT ALL TERMINALS THE REMAINDER OF THE EVENING WITH A 5 TO 10 KNOT SOUTHERLY WIND AND OCCASIONAL GUSTS TO 20 KNOTS. INCREASING RAIN SHOWER COVERAGE IN THE SOUTHWEST OVERNIGHT COULD BRIEFLY BRING ABOUT MVFR CONDITIONS AT CHO. OTHERWISE...VFR CONDITIONS ARE ALL TERMINALS UNTIL AROUND 8Z WHEN WE ANTICIPATE RAIN SHOWERS TO BECOME MORE IN COVERAGE AND POSSIBLY BE ACCOMPANIED BY A FEW RUMBLES OF THUNDER. MVFR CONDITIONS WITH RAIN ACTIVITY. IFR CONDITIONS SEEM MORE PROBABLE BETWEEN 14Z AND 20Z WITH INCREASING RAIN SHOWER AND THUNDERSTORM COVERAGE AS A STRONG COLD FRONT PASSES ACROSS THE REGION. WHILE RAIN ACTIVITY DECREASES FROM WEST TO EAST...WINDS WILL SHIFT TO THE NORTHWEST AND BECOME QUITE GUSTY. GUSTS BETWEEN 30 AND 40 KNOTS EXPECTED LATE TUESDAY AND TUESDAY NIGHT. HIGH PRESSURE BUILDS IN FOR LESS WIND WEDNESDAY. NO SIGNIFICANT WX EXPECTED TO END THE WEEK.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
A SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE OVERNIGHT HOURS AND MUCH OF TUESDAY. A STRONG COLD FRONT WILL SWING ACROSS THE WATERS BY LATE AFTN TUE...SPREADING NEAR GALE GUSTS ON TUE AFTN. HIGHEST CONFIDENCE IN GALES IS BEHIND THE FRONT WITH A NORTHWEST SURGE AND GALE WARNING HAS BEEN ISSUED FOR THIS PERIOD. HIGH PRESSURE BUILDS IN FOR WEDNESDAY. SMALL CRAFT ADVISORY LEVEL WIND GUSTS ARE POSSIBLE FOR PARTS OF THE WATERS THURSDAY NIGHT...AND AGAIN OVER THE WEEKEND DEPENDING ON THE EVOLUTION OF LOW PRESSURE MOVING NEAR THE AREA.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
POSITIVE TIDAL ANOMALIES REMAIN IN THE 1/2-3/4 FOOT RANGE FOR THE WRN SHORES OF THE MD CHSPK BAY. THE STEADY AND GUSTY SLY WINDS WILL KEEP THESE LEVELS STEADY OVERNIGHT AND THRU EARLY TUESDAY MRNG. A FULL MOON UPCOMING...LIKELY HELPING WATER LEVELS TO APPROACH MINOR FLOOD CRITERIA AT THE MORE SENSITIVE LOCATIONS AROUND TIMES OF THE HIGHER HIGH TIDES EARLY TUESDAY MRNG. CBOFS GUIDANCE HOWEVER FCSTS TIDAL LVLS BELOW MINOR COASTAL FLOODING THRESHOLDS AT ALL SITES.
-- End Changed Discussion --
&& .CLIMATE...
-- Changed Discussion --
DEPENDING ON HOW LOW TEMPERATURES GET THIS EVENING...RECORD DAILY HIGH MINIMUM TEMPERATURES COULD BE TIED OR BROKEN AT DCA...BWI AND IAD. BELOW IS A TABLE OF RECORDS FOR THE DAY AND LOW TEMPERATURES OBSERVED SO FAR. SITE...PREVIOUS RECORD...LOW SO FAR... DCA....63 F IN 1896......65 F......... BWI....62 F IN 1896......62 F......... IAD....58 F IN 1972......63 F.........
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...FREEZE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING FOR DCZ001. MD...FREEZE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING FOR MDZ004>007-009>011-013-014-016. VA...FREEZE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING FOR VAZ036>040-042-050>057-501-502. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT TUESDAY FOR ANZ530>543. GALE WARNING FROM 6 PM TUESDAY TO 6 AM EDT WEDNESDAY FOR ANZ530>543. && $$ SYNOPSIS...KLW NEAR TERM...KLW SHORT TERM...BPP LONG TERM...DFH AVIATION...BPP/KLW/DFH MARINE...BPP/KLW/DFH TIDES/COASTAL FLOODING... CLIMATE...

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