Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | 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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
935 FXUS61 KLWX 300051 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 851 PM EDT FRI APR 29 2016 .SYNOPSIS... STALLED FRONTAL BOUNDARY WILL WAVER ACROSS THE AREA THROUGH SATURDAY...THEN LOW PRESSURE MOVES THROUGH THE MID- ATLANTIC SUNDAY AND MONDAY. ANOTHER FRONT WILL MOVE THROUGH LATER NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
A BOUNDARY REMAINS NEARLY STATIONARY ACROSS THE ALLEGHENY HIGHLANDS SOUTHEAST INTO NORTH CAROLINA THIS EVENING. A SHORTWAVE IS PASSING BY TO THE NORTH AS WELL. AN EAST TO NORTHEAST FLOW WILL CONTINUE TO USHER IN COOL CONDITIONS ACROSS OUR CWA BEHIND THE BOUNDARY. THE ONSHORE FLOW WILL CONTINUE TO CAUSE MOISTURE TO BE TRAPPED UNDERNEATH THE SUBSIDENCE INVERSION...RESULTING IN LOW CLOUDS ALONG WITH PATCHY FOG. FOG MAY BE LOCALLY DENSE ACROSS THE HIGHER ELEVATIONS ABOVE 2KFT. THE SHORTWAVE HAS TRIGGERED LIGHT RAIN ACROSS NORTHERN PORTIONS OF THE CWA...BUT RAINFALL COVERAGE IS LIMITED SINCE MOST OF THE FORCING IS OFF TO THE NORTH. THE SHORTWAVE WILL MOVE AWAY FROM THE AREA OVERNIGHT...BRINGING ANY STEADY RAIN WITH IT. HOWEVER...OCCASIONAL DRIZZLE WILL CONTINUE THROUGH TONIGHT DUE TO THE ONSHORE FLOW. MIN TEMPS TONIGHT WILL RANGE FROM THE MID TO UPPER 40S ACROSS NORTHERN MARYLAND TO THE LOWER AND MIDDLE 50S IN CENTRAL VIRGINIA.
-- End Changed Discussion --
&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... THE MOST RECENT MDL RUNS /06Z AND 12Z/ ARE TRENDING WETTER...AND THUS HV INCREASED POPS A PINCH FOR LATE DAY SAT...AND FURTHER INTO CAT TERRITORY FOR SAT NGT AND SUN. SAT CULPRIT WL BE ISENT LIFT...WHICH IMPRV THRU THE DAY. BY LT DAY...HV LKLY POPS. A SOLID SWATH OF MSTR EMINATES FM THE GLFMEX /PWAT EXCEEDS AN INCH/...WHICH SUPPORTS DECISION TO INCR TO CAT POPS BY SAT NGT...AS WELL AS INCR TO MDT RAFL IN OUR DATABASE. SFC LOPRES AND H5 VORT TRACK ALONG THE STALLED BNDRY UP THE OHVLY SUN INTO SUN NGT. THIS PATH TAKES THE BNDRY N OF THE CWA...AND DISLODGES LLVL WEDGE. AM A BIT SKEPTICAL OF FULL SCOURING DUE TO CLIMO...BUT AT THE VERY LEAST IT APPEARS AS THOUGH THERE WL BE AN ELEVATED UNSTBL LYR. ISENT LIFT/MSTR ADVCTN WL CONT TO FUEL THIS SYSTEM. AM ATTEMPTING TO PROVIDE A LTL DEFINITION BY CAPTURING A DIURNAL MIN /RELATIVELY SPEAKING/ IN THE MRNG...FLLWD BY CAT POPS WHEN DAYTIME HEATING WL HV THE BIGGER IMPACT. IN ADDITION...AM A LTL MORE EXPANSIVE IN AREA OF CHC THUNDER...AT LEAST FM AN ELEVATED SENSE. SHEAR LOOKS GOOD...BUT AM CHALLENGED TO SEE TOO MUCH SFC BASED INSTBY. && .LONG TERM /MONDAY THROUGH FRIDAY/... LOW PRESSURE DEPARTS TO THE NORTHEAST MONDAY...BUT THE FRONTAL BOUNDARY IT RODE IN ON WILL REMAIN STALLED NEAR THE REGION THROUGH MUCH OF NEXT WEEK. MULTIPLE AREAS OF LOW PRESSURE WILL CONTINUE TO DEVELOP AND MOVE ALONG IT...AS THE LARGE SCALE TROUGH RESPONSIBLE FOR THIS ACTIVE PATTERN PERSISTS OVER EASTERN NORTH AMERICA. THIS WILL ALSO LEAD TO BELOW NORMAL TEMPERATURES THROUGH MUCH OF NEXT WEEK...WITH HIGHS STRUGGLING TO REACH 70. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
LOW CLOUDS AND DRIZZLE WILL CONTINUE BEHIND A BOUNDARY OVER THE ALLEGHENY HIGHLANDS TONIGHT. IFR CIGS ALONG WITH MVFR AND IFR VSBYS ARE EXPECTED DURING THIS TIME. CONDS WL GRDLY IMPRV SAT...ALTHO FLGT RESTRICTIONS REMAIN. THERE IS A CHC AT BRIEF VFR PRIOR TO RAFL ARRIVING. ATTM CONFIDENCE TOO LOW TO CARVE OUT A WINDOW OF VFR IN THE TAFS. LT AFTN OR EVE SAT CONDS WL DROP AS RA OVERSPREADS THE AREA. RA MAY BE MDT TO BRIEFLY HVY SAT NGT INTO SUN. FLGT RESTRICTIONS WL BE WIDESPREAD. POOR FLYING CONDS CARRY OVER INTO SUN...THO BREAKS IN THE OVC PSBL AS BDRY ATTEMPTS TO WIGGLE N OF THE TERMINALS. HWVR THAT ALSO YIELDS A THUNDER RISK. SUB-VFR PSBL MON-TUE IN ANY LWR CIGS/-RA W/ FRONT STALLED NEARBY. WINDS GENERALLY NELY 10 KTS.
-- End Changed Discussion --
&& .MARINE... PREV FCST REMAINS ON TRACK. ONSHORE FLOW WILL CONTINUE THROUGH SATURDAY. GENERALLY EXPECTING 5- 10 KT WITH OCCASIONAL INCREASES TO 15 KT. LIGHT FOG AND DZ WILL CONTINUE AT TIMES. NEXT ROUND OF RAIN AND ASSOCIATED LLJ REACHES WATERS BY ELY SAT EVNG. AM KEEPING WINDS UNDER SCA CRITERIA THRU SAT NGT EVEN THO WINDS ALOFT INCREASE DUE TO POOR MIXING. MIXING MAY IMPROVE ON SUN...PSBLY AFTN/EVE...BUT CONFIDENCE ON THAT RATHER LOW. THUNDERSTORMS WILL BE POSSIBLE SUNDAY AFTERNOON AND EVENING. SCA CONDITIONS ALSO REMAIN POSSIBLE SUN-MON WITH LOW PRESSURE PASSING ON MONDAY. A FRONTAL BOUNDARY STALLED NEAR OR JUST SOUTH OF THE WATERS SHOULD RESULT IN A WEAK ENOUGH GRADIENT TO PRECLUDE SMALL CRAFT ADVISORIES MONDAY INTO TUESDAY. && .TIDES/COASTAL FLOODING...
-- Changed Discussion --
TIDAL ANOMALIES ARE AROUND ONE-HALF TO THREE QUARTERS OF A FOOT ABOVE NORMAL. A PERSISTENT ONSHORE FLOW WILL CAUSE ANOMALIES TO HOLD NEARLY STEADY OR EVEN INCREASE A BIT THROUGH SATURDAY. HOWEVER...THE FLOW SHOULD BE LIGHT ENOUGH FOR WATER LEVELS TO REMAIN BELOW MINOR FLOODING THRESHOLDS. THE FLOW MAY STRENGTHEN A BIT SUNDAY...CAUSING WATER LEVELS TO APPROACH MINOR FLOODING THRESHOLDS BUT CONFIDENCE REMAINS LOW AT THIS TIME.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...RCM/HTS NEAR TERM...BJL/HTS SHORT TERM...HTS LONG TERM...DFH AVIATION...BJL/HTS/DFH MARINE...BJL/DFH 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.