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 231902 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 302 PM EDT WED APR 23 2014 .SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE WILL BUILD OVER THE AREA THROUGH THURSDAY. A COLD FRONT WILL PASS THROUGH THE AREA FRIDAY AND ANOTHER COLD FRONT IS EXPECTED TO MOVE THROUGH SATURDAY. HIGH PRESSURE WILL BUILD OVERHEAD SUNDAY AS THE COLD FRONT STALLS TO OUR SOUTH. WAVES OF LOW PRESSURE WILL DEVELOP ALONG THE STALLED BOUNDARY...BRINGING UNSETTLED CONDITIONS TO THE AREA NEXT WEEK.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
AT 18Z...A 1025 MB SFC HIGH IS POSITIONED OVER THE UPPER MIDWEST/ GREAT LAKES WHILE A COLD FRONT ASSOCIATED WITH A 995 MB SFC LOW NEAR THE GULF OF MAINE STRETCHES SOUTHWESTWARD TOWARD THE SERN ATLANTIC COAST. GUSTY NW WINDS WILL CONTINUE THRU SUNSET AS A RESULT OF A TIGHT PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS ACROSS THE MID-ATLANTIC STATES. MAX TEMPS WILL LIKELY FALL SHORT OF 60F THIS AFTN ACROSS NRN VA...ERN WV AND WRN/CENTRAL MD DUE TO CAA AND STRATOCU THAT HAS BEEN STUBBORN TO ERODE. EXPECT CLOUDS TO DIMINISH FROM S TO N THRU SUNSET AS SUBSIDENCE STRENGTHENS WHILE THE LOW PULLS AWAY FROM THE EAST COAST. HIPRES CONTINUES TO BUILD EWD TNGT WITH SFC RIDGE AXIS REACHING THE CENTRAL APPALACHIANS LATE TNGT. WINDS WILL RELAX AFTER SUNSET AND BECOME LGT ALONG AND WEST OF THE BLUE RIDGE. DESPITE FCST MIN TEMPS IN THE MID 30S ACROSS THE WRN AND NRN SUBURBS OF DC/BALTIMORE... WINDS AND DRY AIRMASS SHOULD INHIBIT FROST FORMATION. PATCHY FROST POSSIBLE TOWARD THE CENTRAL FOOTHILLS...WHERE THE GROWING SEASON IS ACTIVE. HIPRES MOVES OVERHEAD ON THU. THERE IS STILL SOME TIMING DIFFERENCES CONCERNING HOW QUICKLY THE HIGH MOVES IN WHICH WILL PLAY A FACTOR IN HOW STRONG THE WINDS ARE IN NORTH-CENTRAL MD. THE 12Z GFS WAS PROGRESSIVE ENOUGH WITH THIS SYSTEM THAT WINDS ARE LGT ACROSS THE ENTIRE AREA ALL DAY WHILE THE SLOWER NAM KEEPS WINDS OF 15-25 MPH TOWARD THE GREATER BALTIMORE METRO. UNDER FULL SUNSHINE...MAX TEMPS SHOULD REACH THE MID TO UPPER 60S ACROSS THE MAJORITY OF THE CWA EXCEPT FOR COOLER SPOTS NEAR THE MASON-DIXON LINE AND IN THE MTS. HIPRES MOVES OFFSHORE THU NGT. SLY RETURN FLOW DEVELOPS AND CLOUDS SPREAD IN FROM THE WEST AHEAD OF THE NEXT LOPRES SYSTEM THAT WILL BE MOVING INTO THE UPPER MIDWEST. OVERRUNNING SHOWERS WILL BE ON THE DOORSTEP OF THE ALLEGHENY FRONT TOWARD DAYBREAK FRI MRNG.
-- End Changed Discussion --
&& .SHORT TERM /FRIDAY THROUGH SATURDAY/...
-- Changed Discussion --
A WEAK COLD FRONT SHOULD BE MOVING ACROSS THE APPALACHIANS MTNS FRIDAY MORNING AS A SFC LOW MOVES ACROSS THE GREAT LAKES. RETURN FLOW WILL BE USHERING IN WARM AND MOIST CONDITIONS AHEAD OF THE FRONT AND PWAT VALUES ARE EXPECTED TO RISE AROUND 1.3 INCHES BY FRI AFTERNOON. MID LEVEL FORCING ALONG THE SFC FROPA WILL BE MOVING ACROSS THE MID ATLANTIC FRIDAY AFTERNOON. SHOWERS ARE EXPECTED TO SPREAD ACROSS THE REGION AHEAD AND ALONG THE FROPA. SFC HEATING IN CENTRAL VA WILL LIKELY LEAD TO HEAVIER SHOWERS AND EVEN A ISO THUNDERSTORM. A BRIEF PERIOD OF DRYING WILL MOVE INTO THE REGION BEHIND THE FROPA SATURDAY NIGHT. A SECOND COLD FRONT WILL ROTATE AROUND THE GREAT LAKES LOW AND MOVE ACROSS THE MID ATLANTIC SATURDAY. DEPENDING ON THE SPEED OF THE FROPA TEMPS WILL RANGE FROM THE 50S TO THE MID 70S ACROSS THE REGION. AT THIS TIME KEPT TEMPS EAST OF THE BLUE RIDGE AND VALLEY LOCATIONS IN THE MID TO UPPER 70S. IF THE FROPA MOVES FASTER TEMPS WILL BE LOWER. LITTLE QPF IF ANY IS EXPECTED WITH THE FROPA. LEANED TOWARDS THE GFS AND PUT CHANCE OF SHOWERS FOR THE POTOMAC HIGHLANDS AND NW SUBURBS OF DC AND BALTIMORE SATURDAY DUE TO A SHORTWAVE TROUGH CROSSING THE REGION.
-- End Changed Discussion --
&& .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
THE PRESSURE GRADIENT OVER THE AREA WILL SLOWLY WEAKEN AND LEAD TO GRADUALLY SUBSIDING NORTHWEST WINDS SATURDAY NIGHT INTO SUNDAY. BREEZY AND DRY CONDITIONS ARE EXPECTED WITH TEMPERATURES NEAR NORMAL. HIGH PRESSURE WILL ANCHOR ITSELF OVER NEW ENGLAND BY SUNDAY NIGHT AS A LARGE AND SLOW-MOVING LOW PRESSURE SYSTEM TAKES SHAPE OVER THE GREAT PLAINS. CLOUDS WILL SPILL OVER THE RIDGE IN PLACE OVER THE AREA...STARTING AS THIN HIGH CIRRUS DURING THE DAY SUNDAY BUT LOWERING AND THICKENING SUNDAY NIGHT THROUGH MONDAY. CHANCES FOR RAIN GRADUALLY INCREASE FROM SOUTHWEST TO NORTHEAST MONDAY INTO MONDAY NIGHT AS THE ATMOSPHERE CONTINUES TO MOISTEN. LOW PRESSURE SLOWLY MOVES NORTHEASTWARD INTO THE OHIO VALLEY TUESDAY INTO WEDNESDAY. THERE IS A LARGE SPREAD IN THE GUIDANCE REGARDING THE EXACT TIMING AND EXTENT OF RAINFALL...AS WELL AS THE TRACK OF LOW PRESSURE AND THE NORTHWARD PROGRESSION OF A DEVELOPING WARM FRONT OVER THE CAROLINAS. THIS IS DUE TO A VERY COMPLEX PATTERN...WITH A STRONG CUTOFF LOW OVER THE CANADIAN MARITIMES INTERACTING WITH THE LOW PRESSURE MOVING OUT OF THE CENTRAL UNITED STATES...AND A RIDGE OF HIGH PRESSURE PINCHED IN BETWEEN OVER NEW ENGLAND. THEREFORE...THERE IS A HIGH LEVEL OF UNCERTAINTY IN DETAILS SUCH AS THE CHANCES FOR THUNDERSTORMS...WINDS AND RAINFALL AMOUNTS. DEPENDING ON THE EVOLUTION OF LOW PRESSURE...UNSETTLED WEATHER COULD LINGER INTO THE MIDDLE OF NEXT WEEK.
-- End Changed Discussion --
&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
BREEZY NW WINDS WINDS 15-20 KT WILL CONTINUE TO GUST TO AROUND 30 KT THRU 22Z. WINDS GRADUALLY SUBSIDE THIS EVE PARTICULARLY AFTER SUNSET. CU FIELD AROUND 5 KFT QUICKLY DISSIPATING THIS AFTN. NW WINDS AROUND 10-15 KT TNGT...BECOMING LGT TOWARD DAYBREAK AT CHO/MRB AS HIPRES SHIFTS OVERHEAD. THE PRESSURE GRADIENT AND WIND FIELD CONTINUES TO WEAKEN FROM WEST TO EAST ON THU WITH THE HIGH MOVING OVERHEAD. NW WINDS NEAR 15 KT STILL EXPECTED AT BWI/MTN. LGT SLY WINDS DEVELOP THU NGT ONCE HIPRES PROGRESSES OFFSHORE. SHOWERS ARE EXPECTED FRIDAY AS A WEAK COLD FRONT MOVES ACROSS THE MID ATLANTIC. VCTS IS POSSIBLE FOR CENTRAL VA FRIDAY AFTERNOON AND EARLY EVENING. SLY WINDS WILL BECOME W-NW BEHIND THE FROPA FRIDAY NIGHT INTO SATURDAY. ANOTHER COLD FRONT WILL CROSS THE REGION SATURDAY. GUSTS UP TO 30KTS ARE POSSIBLE SATURDAY AFTERNOON. MODERATE CONFIDENCE IN VFR CONDITIONS WITH NORTHWEST WINDS 10 TO 15 KNOTS SUNDAY INTO SUNDAY NIGHT.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
LATEST MARINE OBS INDICATE HIGH-END SCA OCCURRING AREA WIDE. OPTED TO KEEP THE GALE WARNING GOING WITH OCCASIONAL GUSTS IN THE LOW TO MID 30S STILL BEING OBSERVED. WINDS SUBSIDE A BIT AFTER SUNSET BUT NW WINDS 15-25 KT SHOULD STILL CONTINUE TNGT. SCA REMAINS IN EFFECT FOR THU BUT CONDITIONS MORE MARGINAL. SCA MAY BE ABLE TO BE CANCELLED A FEW HRS EARLY ON THU DEPENDING ON HOW QUICKLY THE AXIS OF THE HIGH BUILDS OVER THE WATERS. SLY WINDS WILL INCREASE FRIDAY AHEAD OF A WEAK COLD FRONT. SCA MAY BE NEEDED AS GUSTS INCREASE IN THE LOWER BAY AND LOWER TIDAL POTOMAC. WINDS WILL BECOME WRLY BEFORE ANOTHER FROPA CROSS THE WATERS SATURDAY AFTERNOON. GUSTY NW WINDS ARE LIKELY SATURDAY AFTERNOON AND A GALE WARNING IS EVEN POSSIBLE. SMALL CRAFT ADVISORY GUSTS MAY LINGER THROUGH SATURDAY NIGHT AND INTO SUNDAY FOR PORTIONS OF THE WATERS. WINDS BECOME LIGHTER LATE SUNDAY INTO SUNDAY NIGHT AS HIGH PRESSURE PASSES NEAR THE REGION.
-- End Changed Discussion --
&& .FIRE WEATHER...
-- Changed Discussion --
A RED FLAG WARNING REMAINS IN EFFECT FOR THE ENTIRE AREA THRU 8 PM. CLOUD COVER HAS KEPT TEMPS DOWN AND RH UP SO FAR ACROSS THE NRN VA...ERN WV AND NRN MD WHERE NW WINDS OF 20-25 MPH HAVE BEEN GUSTING TO 35 MPH. CLOUDS CONTINUE TO ERODE THOUGH AND RH IS NOW IN THE 30S SO WILL KEEP THE RED FLAG WARNING IN EFFECT. FARTHER SOUTH IN CENTRAL VA...RH HAS DROPPED BELOW 30 PERCENT BUT WINDS ARE GENERALLY AROUND 15 MPH. AFTER COORDINATING WITH VA STATE FIRE OFFICIALS...WILL ALSO KEEP RED FLAG WARNING IN EFFECT. WINDS SUBSIDE TOWARD SUNSET AND RH VALUES WILL INCREASE ABOVE CRITICAL THRESHOLDS. DRIER AIR WILL CAUSE EVEN LOWER RH VALUES THURSDAY...BUT WINDS WILL NOT BE AS STRONG. A FIRE WEATHER WATCH IS IN EFFECT FOR PORTIONS OF CENTRAL AND NORTHEASTERN MARYLAND WHERE THE WINDS WILL BE STRONGEST.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR DCZ001. FIRE WEATHER WATCH FROM THURSDAY MORNING THROUGH THURSDAY AFTERNOON FOR DCZ001. MD...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR MDZ003>007- 009>011-013-014-016>018-502. FIRE WEATHER WATCH FROM THURSDAY MORNING THROUGH THURSDAY AFTERNOON FOR MDZ004>007-009>011-013-014-018. VA...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR VAZ025>031- 036>040-042-050>057-501-502-504. FIRE WEATHER WATCH FROM THURSDAY MORNING THROUGH THURSDAY AFTERNOON FOR VAZ054. WV...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR WVZ050>053- 055-502-504-506. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM EDT THURSDAY FOR ANZ530>543. GALE WARNING UNTIL 6 PM EDT THIS EVENING FOR ANZ530>543. && $$ SYNOPSIS...JRK NEAR TERM...JRK SHORT TERM...HAS LONG TERM...DFH AVIATION...JRK/HAS/DFH MARINE...JRK/HAS/DFH FIRE WEATHER...JRK

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