Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 291915 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 315 PM EDT MON JUN 29 2015 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE EAST FROM THE AREA THROUGH THIS EVENING. LOW PRESSURE WILL PERSIST OVER THE MIDWEST THROUGH TONIGHT AND THEN CROSS LAKES ERIE AND ONTARIO ON TUESDAY...PUSHING A WARM FRONT NORTHEAST ACROSS OUR AREA. A COLD FRONT WILL THEN PUSH SOUTHEAST ACROSS THE AREA ON WEDNESDAY BEFORE STALLING IN THE AREA ON THURSDAY THROUGH SATURDAY. && .NEAR TERM /THROUGH TUESDAY NIGHT/... AS OF 17Z...SFC RIDGE AXIS IS OVER THE VA/MD PIEDMONT PER SFC OBS. SLY FLOW IS WEST AND WLY FLOW IS EAST. THIS AXIS WILL CONTINUE MOVE EAST TO THE BAY THIS AFTERNOON...WITH RETURN SLY FLOW CONTINUING TO SPREAD EAST. MAX TEMPS LOW TO MID 80S. REMNANT AREA OF SHOWERS WITH A FEW THUNDERSTORMS NOW SOUTH AND WEST IS OVER OHIO AND DRIFTING EAST. UPDATED POPS FOR LIKELY RAIN AFTER 6PM IN THE POTOMAC HIGHLANDS. THIS AREA IS AHEAD OF A LOW THAT WILL SPIN OVER THE MIDWEST INTO TUESDAY. AN ASSOCIATED TROUGH ENTERS THE AREA TUESDAY. EXPECT PATCHY RAIN/SHOWERS MAINLY WEST FROM THE BLUE RIDGE TONIGHT/TUESDAY MORNING...THEN LIKELY TRIGGERING ISO/SCT TSTMS ACROSS THE AREA TUESDAY AFTERNOON/EVENING. MAX TEMPS MID TO UPR 80S...AROUND 90F ALONG I-95. TUESDAY NIGHT...TROUGH LINGERS OVER THE AREA...ACTIVITY SHOULD SHIFT EAST TO THE BAY THROUGH THE NIGHT. THE UPR TROUGH ENTERS THE CNTRL APPALACHIANS LATE IN THE NIGHT...WITH SCATTERED SHOWERS POSSIBLE. MIN TEMPS LOW TO MID 60S WEST OF THE BLUE RIDGE...UPR 60S TO LOW 70S EAST...MID 70S NEAR SHORE. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... TROF AXIS MOVE SLGTLY EAST ON WED WHILE CDFNT CREEPS SEWD TWD AREA. OVERALL FORCING MECHANISMS DO NOT LOOK THAT GREAT. HWVR...IF EURO DEPICTION OF S/WV CROSSING MD DURING THE DAY PANS OUT...THEN THERE WL BE A BETTER CHC AT TSRA. SHEAR EXITS ELY...BUT STILL HV FVRBL INSTBY PARAMETERS. HV TAKEN POPS DOWN A BIT...FCST GNLY ARND 30-40 PCT...BUT PLACED A BIT MORE EMPHASIS IN THE LEE TROF LT IN THE DAY. DIMINISHED PCPN AFTER LOSS OF DAYTIME HEATING. KEPT TEMPS NEAR NORMAL. && .LONG TERM /THURSDAY THROUGH MONDAY/... AT 12Z THU MEANDERING FRONT IS CURRENTLY PROGGED TO BE ALONG OUR NORTHERN BORDER WITH MOST...IF NOT ALL...OF OUR AREA IN THE WARM SECTOR. SOME QUESTION REMAINS WITH REGARDS TO TIMING OF FRONTAL PASSAGE...WITH SOME GUIDANCE SUGGESTING FRONT PASSES THROUGH EARLY...WHILE OTHERS SUGGEST A LATER PASSAGE. REGARDLESS...SFC LP TRACKS ALONG THE FRONT AND...WITH BAROCLINICITY...SOME UPPER LEVEL SUPPORT...AND DEEP MOISTURE...COULD SETUP A RATHER WET PERIOD. UPPER LEVEL FLOW NOT OVERLY IMPRESSIVE (AOB 30 KTS AT 5H) AS SUBTLE SHORT WAVE APPROACHES THE AREA...SO NOT EXPECTING EXTREMELY ORGANIZED STORMS...THOUGH COULD BE ENOUGH INSTABILITY FOR STRONGER PULSE-TYPE STORMS. FRONT OSCILLATES AROUND THE AREA THROUGH THE REMAINDER OF THE PERIOD...WHICH KEEPS FORECAST MUDDLED. CHC POPS REMAIN IN THE FORECAST EACH DAY FOR MAINLY DIURNAL TSTM ACTIVITY. WITH THE TYPICALLY FAVORED HIGHER TERRAIN LOCATIONS HAVING THE HIGHEST POPS. TEMPS EXPECTED TO REMAIN NEAR NORMAL THROUGH THE EXTENDED PERIOD...WITH A SLIGHT INCREASE THROUGH THE WEEKEND. DEWPOINTS NOT OVERLY OPPRESSIVE...GENERALLY AOB 70F...WHICH SHOULD KEEP IT FROM GETTING TOO UNCOMFORTABLE. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... VFR THROUGH TUESDAY MORNING BEFORE MVFR/IFR POSSIBLE IN TUESDAY AFTERNOON/EVENING SCATTERED THUNDERSTORMS ACROSS THE TERMINALS. FLOW BECOMES SLY REST OF THE AFTERNOON AS HIGH PRESSURE SHIFTS EAST TO THE COAST. SLY FLOW INCREASES TUESDAY INTO TUESDAY NIGHT WITH GUSTS AROUND 20 KT. LOW CONFIDENCE IN FLGT RESTRICTIONS WED. POTL CERTAINLY THERE...BUT TIMING/PLACEMENT A REAL STRUGGLE. VFR SHUD PREVAIL MOST OF THE TIME. MOST PERIODS THU THRU SAT WILL BE VFR...THOUGH EXPECT SUB-VFR CONDS IN ANY TSTM ACTIVITY. VARIABLE WINDS EXPECTED THROUGH THE PERIOD. && .MARINE... LIGHT WLY FLOW BECOMES SLY WITH CHANNELING AROUND 15 KT LATE THIS EVENING AS HIGH PRESSURE SHIFTS EAST OVER THE BAY REGION. SLY FLOW INCREASES TO 15 TO 20 KT WITH GUSTS UP TO 25 KT. SCA FOR ALL WATERS BEGINS AT 10AM TUESDAY AND CONTINUES UNTIL 8PM...CONTINUES INTO THE OVERNIGHT FOR MOST OF THE WATERS. SCATTERED GUSTY THUNDERSTORMS DEVELOP LATE TUESDAY AFTERNOON AND CONTINUE THROUGH TUESDAY NIGHT. WINDS AOB 10 KT WED-WED NGT...MAINLY FM THE SW. WINDS EXPECTED TO REMAIN BELOW SCA CRITERIA THROUGH THE EXTENDED...THOUGH WILL NEED TO MONITOR AS FRONT WILL BE NEAR AREA EACH DAY. AFTN TSTMS ARE ALSO POSSIBLE EACH DAY...WHICH COULD IMPACT MARINE CONCERNS. && .TIDES/COASTAL FLOODING... WATER LVLS LIKELY WL BE INCREASING TUE...AND MAY APPROACH MINOR THRESHOLDS AT SENSITIVE LOCATIONS BY WED DURING THE HIGHER HIGH TIDE...WHICH IS THE AM CYCLE /MIDNGT THRU NOON/. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM TUESDAY TO 4 AM EDT WEDNESDAY FOR ANZ531>534-536-537-539>543. SMALL CRAFT ADVISORY FROM 10 AM TO 8 PM EDT TUESDAY FOR ANZ530- 535-538. && $$ SYNOPSIS...BAJ NEAR TERM...BAJ SHORT TERM...HTS LONG TERM...MSE AVIATION...BAJ/HTS/MSE MARINE...BAJ/HTS/MSE TIDES/COASTAL FLOODING...HTS

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