Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 240112 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 912 PM EDT SAT MAY 23 2015 .SYNOPSIS... HIGH PRESSURE WILL GRADUALLY SLIDE OFF THE EAST COAST TONIGHT AND LINGER TO THE EAST THROUGH MEMORIAL DAY. THE RETURN FLOW WILL RESULT IN WARMER TEMPERATURES AND HIGHER HUMIDITY. HOT AND HUMID WEATHER WILL DOMINATE TUESDAY AND WEDNESDAY BETWEEN THE HIGH TO THE EAST AND AN APPROACHING FRONT TO THE WEST...WITH AN INCREASING RISK OF SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH SUNDAY/... THE CENTER OF SFC HIGH PRESSURE WILL BE SLIDING EAST OF THE DELMARVA TONIGHT UNDER A WNW FLOW ALOFT. MAINLY CLEAR SKIES EXIST ACROSS THE AREA NOW...AND ONLY SOME STRANDS OF THIN CIRRUS ARE EXPECTED OVERNIGHT. WITH DEW POINTS STILL IN THE 40S...WITH 30S IN THE N...TEMPS ARE FALLING QUICKLY WITH SUNSET. WHILE WARMER THAN LAST NIGHT...MANY AREAS WILL STILL BE BELOW NORMAL FOR LATE MAY. THE LOWEST TEMPS WILL BE THE HIGHEST ELEVATIONS AND RURAL LOW-LYING AREAS (MID-UPPER 40S)...WHILE MID RANGE ELEVATIONS (UNDER INFLUENCE OF AN INVERSION) AND URBAN AREAS WILL REMAIN IN THE MID 50S. WITH THE HIGH CONTINUING TO MOVE OFFSHORE...WARMER AIR MOVING IN ALOFT WILL ALLOW TEMPERATURES TO BE ABOUT 10 DEGREES WARMER ON SUNDAY. AN APPROACHING AND BUILDING RIDGE AXIS MOVING IN FROM THE SOUTHWEST WILL KEEP SUBSIDENCE IN PLACE...PREVENTING ANY PRECIPITATION. HOWEVER...WARM ADVECTION WILL PROBABLY RESULT IN INCREASED CLOUD COVER BY SUNDAY AFTERNOON. DEW POINTS WILL BE ABOUT 20 DEGREES HIGHER ON SUNDAY AFTERNOON COMPARED TO CURRENT READINGS...BUT NOT QUITE IN THE `HUMID` RANGE JUST YET. SOUTHERLY WINDS WILL START TO BECOME NOTICEABLE BUT NOTHING PARTICULARLY BREEZY IS EXPECTED INLAND THRU SUNDAY AFTERNOON. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/... AN UPPER LEVEL RIDGE WILL MOVE OVERHEAD SUNDAY NIGHT AND MONDAY. HIGH PRESSURE WILL BE OFF THE EAST COAST AND SOUTHERLY WINDS WILL CONTINUE TO TRANSPORT HEAT AND HUMIDITY. TEMPS ARE EXPECTED TO RISE INTO THE UPPER 80S TO NEAR 90 IN DC/BALTIMORE MONDAY AFTERNOON. MOISTURE WILL INCREASE ACROSS THE AREA BUT THE MAIN PLUME OF HIGH PWATS WILL BE ACROSS THE MISSISSIPPI VALLEY MONDAY. TERRAIN CIRCULATIONS WILL LIKELY PRODUCE A CU FIELD ALONG THE RIDGES AND CANT RULE OUT A STRAY SHOWER. THE RIDGE WILL GRADUALLY BREAK DOWN MONDAY NIGHT THROUGH TUESDAY NIGHT. A CHANCE OF SHOWERS AND THUNDERSTORMS WILL EVOLVE DURING THE DAY TUESDAY AS UPPER LEVEL WAVES OF ENERGY RIDE ALONG THE OHIO VALLEY. MOST OF THE ACTIVITY WILL BE FOCUSED FROM THE POTOMAC HIGHLANDS TO THE BLUE RIDGE. EXPECT HIGH TEMPERATURES TUESDAY TO REACH NEAR 90 OR INTO THE LOWER 90S WHILE LOW TEMPERATURES MONDAY NIGHT AND TUESDAY NIGHT WILL BE IN THE MIDDLE TO UPPER 60S. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... THE THREAT FOR SHOWERS AND THUNDERSTORMS PUSHES A LITTLE FARTHER EAST TO THE CHESAPEAKE BAY AND I-95 CORRIDOR WEDNESDAY THROUGH THURSDAY NIGHT AS A FEW ADDITIONAL DISTURBANCES PUSH ACROSS THE REGION. HIGHS WEDNESDAY AND THURSDAY WILL APPROACH 90 WITH A WARM AND STICKY NIGHT IN STORE FOR WEDNESDAY NIGHT AND AGAIN THURSDAY NIGHT. A STRONGER DISTURBANCE WILL PIVOT ACROSS THE OHIO VALLEY FRIDAY AND FRIDAY NIGHT...KEEPING THE POTENTIAL FOR SHOWERS AND GUSTY THUNDERSTORMS AROUND TO START THE WEEKEND. HIGHS IN THE UPPER 80S AND LOWS IN THE MIDDLE 60S. A SURFACE COLD FRONT WILL DEVELOP ALONG THE SOUTHERN FLANK OF THE UPPER DISTURBANCE SATURDAY. THIS FRONT WILL BE THE FOCAL ZONE OF SHOWERS AND A FEW THUNDERSTORMS. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... HIGH PRESSURE WILL MOVE OFFSHORE THROUGH SUNDAY. IF A BRIEF PERIOD OF MVFR VSBY DEVELOPED LATE TONIGHT/EARLY SUNDAY DUE TO LOW LEVELS SATURATING UNDER CLEAR/CALM CONDS...MRB AND CHO WOULD STAND THE BEST CHANCE. HOWEVER DUE TO THE DRY AIRMASS IN PLACE...FEEL THIS IS A LOW PROBABILITY AND WILL NOT INCLUDE IT IN THE TAFS FOR NOW. OTHERWISE VFR CONDITIONS THROUGH SUNDAY NIGHT. FEW-SCT CU AROUND 6 KFT POSSIBLE SUNDAY AFTERNOON. LIGHT/VRB WINDS TONIGHT BECOME MORE DEFINED FROM THE SOUTH SUNDAY WITH SUSTAINED SPEEDS LESS THAN 10 KT. WIND GUSTS MAY POTENTIALLY EXCEED 25 KNOTS ON MONDAY. NO PRECIPITATION EXPECTED THROUGH MONDAY NIGHT. WINDS WILL SLACKEN A BIT MONDAY NIGHT. MVFR TO IFR CONDITIONS MAY OCCUR AT MRB...CHO AND IAD TERMINALS WITH SHOWERS AND THUNDERSTORMS AROUND TUESDAY AND TUESDAY NIGHT. ALL OTHER TERMINALS WILL BE MAINLY VFR. WINDS SOUTH TO SOUTHWEST 5 TO 10 KNOTS GUSTS TO 15 KNOTS. MVFR TO IFR CONDITIONS AT ALL TERMINALS WEDNESDAY THROUGH THURSDAY WITH ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING AND MOVING EAST ACROSS THE REGION. WINDS SOUTHWEST 5 TO 10 KNOTS GUSTS TO 15 KNOTS BECOMING NORTHWEST AT 5 KNOTS WEDNESDAY NIGHT. WINDS BECOMING LIGHT AND VARIABLE THURSDAY. && .MARINE... HIGH PRESSURE WILL PROVIDE LIGHT WINDS AND MOSTLY CLEAR SKIES THROUGH SUNDAY MORNING. AS THE HIGH SLIDES EAST...A SOUTHERLY WIND WILL DEVELOP ON THE BACK SIDE WHICH WILL CHANNEL UP CHESAPEAKE BAY AND PRODUCE MARGINAL SCA CONDITIONS...SO AN ADVISORY WAS ISSUED FOR PRIMARILY THE SOUTHERN WATERS IN OUR RESPONSIBILITY THROUGH SUNDAY NIGHT. NOTE THAT SCA CONDITIONS MAY EXPAND ON MONDAY AND CONTINUE THROUGH MID-WEEK AS THE HIGH PRESSURE SITS OFF THE EAST COAST FOR SEVERAL DAYS PRODUCING A PERSISTENT SOUTHERLY WIND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 6 AM EDT MONDAY FOR ANZ532>534-537-541-543. && $$ SYNOPSIS...RCM NEAR TERM...ADS/RCM SHORT TERM...HAS LONG TERM...KLW AVIATION...ADS/HAS/KLW MARINE...HAS/RCM/KLW

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