Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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. --
000 FXUS61 KLWX 270019 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 819 PM EDT SUN JUL 26 2015 .SYNOPSIS... A COLD FRONT WILL APPROACH THE WATERS FROM THE NORTHWEST TONIGHT. THE FRONT WILL STALL NEAR THE WATERS MONDAY THEN DISSIPATE BY MONDAY NIGHT AS HIGH PRESSURE REGAINS CONTROL. THE HIGH WILL MOVE OFFSHORE WEDNESDAY. && .NEAR TERM /THROUGH MONDAY NIGHT/...
-- Changed Discussion --
A SURFACE TROUGH REMAINS OVER THE SHENANDOAH VALLEY THIS EVENING WHILE AN UPPER-LEVEL DISTURBANCE APPROACHES FROM THE NORTHWEST. A SOUTHERLY FLOW AROUND HIGH PRESSURE OVER THE ATLANTIC HAS ALLOWED FOR MORE HUMID CONDITIONS TO RETURN. THE INCREASED MOISTURE HAS LEAD TO MORE INSTABILITY...AND WITH THE SURFACE TROUGH AROUND A FEW SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE SHENANDOAH VALLEY. THE ACTIVITY SHOULD REMAIN SCATTERED THIS EVENING...ESPECIALLY FOR AREAS NEAR AND WEST OF THE BLUE RIDGE MOUNTAINS. THE UPPER-LEVEL DISTURBANCE WILL PASS THROUGH OVERNIGHT INTO EARLY MONDAY MORNING. A FEW MORE SHOWERS ARE POSSIBLE ALONG WITH A COUPLE THUNDERSTORMS. HAVE THE HIGHEST POPS ACROSS NORTH-CENTRAL AND NORTHEASTERN MARYLAND DURING THIS TIME WHERE FORCING MAY BE STRONGER WITH THE UPPER-LEVEL DISTURBANCE. THE UPPER-LEVEL DISTURBANCE WILL MOVE AWAY FROM THE AREA MONDAY...BUT THE SURFACE TROUGH WILL REMAIN OVERHEAD ALONG WITH MORE WARM AND HUMID CONDITIONS. WEAK SHEAR SHOULD PRECLUDE ANY SEVERE WX...BUT MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE. DRIER AIR WORKS INTO THE AREA LATE MON NIGHT.
-- End Changed Discussion --
&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
A WEAK PRESSURE TROUGH WILL PERSIST OVER SOUTHWESTERN PARTS OF THE CWA TUESDAY AS HIGH PRESSURE BUILDS OVER NORTHERN PARTS OF THE AREA. COULD SEE SCATTERED LOW CLOUDS FIRST THING TUESDAY MORNING AS A LIGHT ONSHORE FLOW TAKES HOLD IN THE WAKE OF THE DISSIPATING FRONTAL BOUNDARY. WITH THE PRESSURE TROUGH IN PLACE AND A LIGHT/MOIST EASTERLY UPSLOPE FLOW...A FEW WIDELY SCATTERED SHOWERS OR A THUNDERSTORM COULD POP UP DURING PEAK HEATING OVER THE SOUTHWESTERN CORNER OF THE AREA. OTHERWISE...JUST SCATTERED- BROKEN DIURNAL CUMULUS EXPECTED WITH TEMPERATURES AT OR SLIGHTLY ABOVE NORMAL. HIGH PRESSURE MOVES OVERHEAD TUESDAY NIGHT. LOWS NEAR NORMAL ARE EXPECTED UNDER A PARTLY TO MOSTLY CLEAR SKY. AS THE HIGH MOVES OFFSHORE WEDNESDAY...HOT AND HUMID SOUTHERLY FLOW WILL RETURN...BOOSTING HIGH TEMPERATURES INTO THE UPPER 80S AND LOWER 90S. HEAT INDEX VALUES MAY APPROACH 100F DURING THE AFTERNOON IN THE METRO AREAS.
-- End Changed Discussion --
&& .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
-- Changed Discussion --
HIGH PRES DOMINATES CONDITIONS WED NIGHT INTO FIRST HALF OF THU BEFORE A COLD FRONT APPROACHES FROM THE NW LATER THAT DAY. SHOWERS AND TSTMS PSBL... WITH UNCERTAINTY IN TIMING AND COVERAGE OF THESE ATTM. FRONT MOVES ACROSS THU NIGHT AND STALLS OVER/OFF THE SE OF OUR CWA THROUGH SUNDAY AS IT WEAKENS. DEPENDING ON HOW CLOSE THIS BOUNDARY STALLS TO OUR AREA... SOME SHOWERS AND TSTMS ARE PSBL IN THE SOUTHERN PART OF OUR CWA... SO KEPT A CHANCE OF POPS DURING THIS PERIOD FOR THAT REGION. HIGH TEMPS WILL BE IN THE MID 90S THU... WITH HEAT INDEXES PSBLY REACHING THE LOW 100S IN SOME AREAS. SAT THROUGH SUN HI TEMPS WILL BE IN THE UPR 80S TO LOW 90S.
-- End Changed Discussion --
&& .AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
SCT THUNDERSTORMS ARE POSSIBLE THIS EVENING...MAINLY WEST OF THE TERMINALS. THEREFORE...THE MENTION FOR THUNDERSTORMS HAVE BEEN MOVED OUT THIS EVENING. AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE AREA LATE TONIGHT INTO MONDAY MORNING. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE DURING THIS TIME. THE UPPER-LEVEL DISTURBANCE WILL MOVE AWAY FROM THE AREA MONDAY...BUT MORE WARM AND HUMID CONDITIONS ARE EXPECTED AND THAT MAY LEAD TO MORE SHOWERS AND THUNDERSTORMS. PATCHY FOG IS POSSIBLE LATE TONIGHT...BUT CLOUD COVER WILL PREVENT WIDESPREAD FOG FROM DEVELOPING. MAINLY VFR EXPECTED TUE-WED. OUTSIDE CHANCE SUB-VFR MAINLY AT BWI/MTN TUE AM W/ POTL STRATUS DUE TO MOIST ELY FLOW. WINDS GENERALLY AOB 10 KT...ELY TUE BCMNG SLY TUE NIGHT-WED AROUND 10 KT. VFR CONDITIONS EXPECTED WED NIGHT INTO EARLY THU. SUB-VFR CONDITIONS PSBL THU AFTN DUE TO SHOWERS AND TSTMS.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SOUTHERLY WINDS WILL CONTINUE TONIGHT. WINDS WILL CHANNEL UP THE BAY AND LOWER TIDAL POTOMAC RIVER...SO A SMALL CRAFT REMAINS IN EFFECT. WINDS SHOULD WEAKEN OVER THE BAY TOMORROW...BUT A FEW GUSTS CLOSE TO SCA CRITERIA ARE STILL POSSIBLE DUE TO SOUTHERLY CHANNELING. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE LATE TONIGHT INTO MONDAY MORNING...AND AGAIN MONDAY AFTERNOON AND EVENING. SUB-SCA CONDITIONS ARE EXPECTED TUESDAY AND TUESDAY NIGHT AS HIGH PRESSURE MOVES OVER THE WATERS. THE HIGH MOVES OFFSHORE WEDNESDAY RESULTING IN SOUTHERLY CHANNELING AND POTENTIAL SMALL CRAFT GUSTS. SCA CONDITIONS PSBL FOR WED NIGHT INTO THU.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
SOUTHERLY FLOW HAS INCREASED AND CONTINUES TO NUDGE TIDAL ANOMALIES UPWARDS THIS EVENING. THE HIGHER OF THE TWO HIGH TIDE CYCLES OVERNIGHT WILL LIKELY RESULT IN MINOR INUNDATION AT VULNERABLE SITES /PARTICULARLY ANNAPOLIS...BUT POSSIBLY UP INTO BALTIMORE HARBOR AS WELL/. ESTOFS IS STILL RUNNING A LITTLE HIGH BUT NOT QUITE AS MUCH HIGHER COMPARED TO OTHER GUIDANCE AS IN PREVIOUS DAYS...SO HAVE CONSIDERED ITS OUTPUT WITH THIS ASSESSMENT. COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR TONIGHT`S HIGH TIDE CYCLE NEAR ANNAPOLIS AND BALTIMORE. THE WATER LEVELS WILL BE CLOSE TO MINOR FLOODING THRESHOLDS ELSEWHERE...BUT CURRENT FEELING IS THAT THEY WILL REMAIN JUST BELOW. THIS IS ALSO CONSISTENT WITH THE LATEST CBOFS AND ESTOFS GUIDANCE AS WELL. THE SOUTHERLY FLOW WILL CONTINUE THROUGH MONDAY...AND MORE MINOR TIDAL FLOODING IS POSSIBLE MONDAY NIGHT INTO TUESDAY MORNING NEAR HIGH TIDE.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...COASTAL FLOOD ADVISORY UNTIL 8 AM EDT MONDAY FOR MDZ011-014. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT MONDAY FOR ANZ530>534- 537>543. COASTAL FLOOD ADVISORY UNTIL 8 AM EDT MONDAY FOR ANZ538.
-- End Changed Discussion --
&& $$ SYNOPSIS...BJL/LFR NEAR TERM...BJL/LFR SHORT TERM...DFH LONG TERM...IMR AVIATION...BJL/IMR/LFR/DFH MARINE...BJL/IMR/LFR/DFH TIDES/COASTAL FLOODING...DFH/LFR/BJL

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