Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 221853 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 253 PM EDT FRI MAY 22 2015 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA THIS EVENING WITH HIGH PRESSURE BUILDING OVERHEAD LATE TONIGHT AND SATURDAY. TEMPERATURES WILL BE NOTICEABLY BELOW NORMAL WITH SOME FROST POSSIBLE IN THE HIGHER TERRAIN WELL NORTH AND WEST OF THE METRO. THE HIGH WILL MOVE OFF THE COAST SUNDAY AND REMAIN IN THE WESTERN ATLANTIC THROUGH MID- WEEK NEXT WEEK WITH NOTICEABLY HOTTER AND MORE HUMID CONDITIONS RETURNING TO THE REGION. && .NEAR TERM /THROUGH SATURDAY/... A CU FIELD AND SCT SHOWERS HAVE DEVELOPED IN VICINITY OF A COLD FRONT IN CENTRAL PA THIS AFTERNOON. THIS ACTIVITY WILL MOVE SOUTHWARD INTO MD THIS AFTERNOON. THE HRRR HAS BEEN PERSISTENT BRINGING ISO-SCT SHOWERS ACROSS THE MASON DIXON LINE BEFORE SUNSET. DUE TO THE DRY CONDITIONS... COVERAGE WILL BE LOW AND ONLY A SPRINKLE OR BRIEF SHOWER IS POSSIBLE. NW WINDS 10-15MPH WITH GUSTS UP TO 25 MPH SHOULD BACK AHEAD OF THE FRONT THIS AFTERNOON BECOMING SOUTHWEST. BEHIND THE FRONT...A VERY DRY AIRMASS WILL MOVE INTO THE MID- ATLANTIC. WINDS WILL BECOME NW AGAIN AND CONTINUE TO SUBSIDE OVERNIGHT. DRY AND CLEAR CONDITIONS WILL ALLOW TEMPS TO DROP INTO THE 40S WITH THE EXCEPTION OF THE METROS SEEING THE 50S AND THE HIGHER ELEVATIONS OF THE ALLGHENY FRONT SEEING THE LOW TO MID 30S. A FROST ADVISORY HAS BEEN ISSUED FOR THIS REGION. HIGH PRESSURE MOVES OVERHEAD SATURDAY. NRLY FLOW WILL KEEP TEMPS BELOW CLIMO IN THE UPPER 60S TO LOW 70S. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... SURFACE HIGH PRESSURE WILL DRIFT EAST INTO THE ATLANTIC OCEAN SATURDAY NIGHT...BUT THE RETURN FLOW WILL BE SLOW AND LOWS WILL ONLY BE A FEW DEGREES MILDER ON SATURDAY NIGHT AS COMPARED TO FRIDAY NIGHT. HUMIDITY WILL START TO COME BACK HOWEVER. OTHERWISE...SKIES SHOULD BE MOSTLY CLEAR AS HEIGHTS ALOFT BUILD AHEAD OF AN APPROACHING RIDGE. THE SURFACE HIGH WILL KEEP DRIFTING SLOWLY EAST SUNDAY WITH THE RETURN FLOW RESULTING IN A NOTICEABLY WARMER AND MORE HUMID DAY AS COMPARED TO SATURDAY. TEMPERATURES WILL RISE AROUND 10 DEGREES WHILE DEW POINT RISE WILL BE MORE LIKE 20 DEGREES. SOME CLOUDS MAY INCREASE IN THE AFTERNOON AS WARM ADVECTION GETS UNDERWAY ALOFT ALONG THE TAIL END OF A WARM FRONT WHICH WILL MOVE BY TO OUR NORTHWEST...BUT NO PRECIPITATION IS EXPECTED WITH HEIGHTS CONTINUING TO BUILD ALOFT AHEAD OF THE STILL APPROACHING AND BUILDING RIDGE AXIS. CLOUDS WILL MAKE FOR A MUCH MILDER NIGHT ON SUNDAY NIGHT AS THE AFOREMENTIONED WARM FRONT PASSES BY TO THE NORTH...BUT AGAIN NO PRECIPITATION IS EXPECTED. ON MONDAY THE SURFACE HIGH PRESSURE WILL CONTINUE DRIFTING SLOWLY EAST. TEMPERATURES WILL APPROACH OR SLIGHTLY EXCEED 90 DEGREES IN MANY AREAS. DEW POINTS STILL WON`T BE TOO HIGH WITH READINGS PROBABLY STAYING IN THE UPPER 50S IN MUCH OF THE AREA...BUT IT WILL STILL FEEL CONSIDERABLY MORE SUMMER-LIKE THAN IT WILL ON SATURDAY. WITH THE RIDGE STILL BUILDING OVERHEAD...AND DEW POINTS NOT ALL THAT HIGH JUST YET...CONSENSUS APPEARS TO BE FAVORABLE FOR A STORM-FREE DAY SO HAVE KEPT THUNDER OUT OF THE FORECAST. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... ECMWF 500 MB RIDGE OVER MID ATLANTIC REGION SLOWLY MOVING TO EAST ALLOWING A SHORT WAVE TO AFFECT THE REGION THURSDAY. MOISTURE AND TEMPERATURES WILL GENERALLY INCREASE ON SOUTHWEST FLOW DURING THE PERIOD. HOT AND HUMID CONDITIONS WILL LEAD TO AN INCREASED CHANCE FOR THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS EACH DAY. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. NW WINDS 10-15KTS G 20-25KTS WILL SUBSIDE TO 5-10KTS TONIGHT. HIGH PRESSURE BUILDS INTO THE REGION SATURDAY AND WINDS WILL DIMINISH TO VARIABLE SAT AFTERNOON THROUGH SATURDAY NIGHT. THE HIGH WILL MOVE OFF THE COAST SUNDAY AND MONDAY. WINDS WILL BECOME SOUTHWESTERLY BUT VFR CONDITIONS WILL CONTINUE WITH NO THUNDERSTORMS EXPECTED. THE RISK FOR STORMS WILL INCREASE TUESDAY AFTERNOON AND EVENING AS HOT AND HUMID CONDITIONS INCREASE INSTABILITY. && .MARINE... W-NW WINDS 10-15KTS G 25KTS WILL CONTINUE ON THE WATERS TODAY. WINDS WILL SUBSIDE ACROSS THE UPPER TIDAL POTOMAC AND CHESAPEAKE BAY NORTH OF POOLES ISLAND TONIGHT. HIGH PRESSURE MOVES OVERHEAD SATURDAY AND NW WINDS WILL BECOME SW BY AFTERNOON ALBEIT 5- 10KTS. HIGH PRESSURE WILL MOVE OFF THE COAST SUNDAY AND MONDAY WITH A SOUTHERLY FLOW RETURNING. THE HIGH WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE MIDDLE PORTION OF NEXT WEEK...ALLOWING FOR THE SOUTHERLY FLOW TO CONTINUE. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS MONDAY THROUGH TUESDAY NIGHT DUE TO THE INCREASING SOUTHERLY FLOW...BUT IT WILL BE MARGINAL DUE TO THE RELATIVELY COOLER WATERS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT SATURDAY FOR MDZ501. VA...NONE. WV...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT SATURDAY FOR WVZ501-503-505. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT SATURDAY FOR ANZ531>534- 537-539>543. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ530- 535-536-538. && $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...RCM LONG TERM...CEM AVIATION...HAS/RCM MARINE...HAS/RCM

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