Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 301943 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 343 PM EDT THU APR 30 2015 .SYNOPSIS...
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LOW PRESSURE WILL IMPACT THE AREA TODAY THROUGH TONIGHT BEFORE MOVING OFFSHORE FRIDAY. HIGH PRESSURE WILL BUILD OVERHEAD DURING THE WEEKEND BEFORE SHIFTING TO THE SOUTH EARLY NEXT WEEK. A COLD FRONT MAY IMPACT THE AREA DURING THE MIDDLE PORTION OF NEXT WEEK.
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&& .NEAR TERM /THROUGH FRIDAY/... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO DEVELOP ACROSS THE REGION THIS AFTERNOON INTO THE EARLY EVENING HOURS. COLD CORE DYNAMICS FROM THE UPPER LOW OVER THE OHIO VALLEY WILL CAUSE STEEP MID LEVEL LAPSE RATES AND LEAD TO SMALL HAIL WITH THE THUNDERSTORM ACTIVITY. THERE IS NOT ENOUGH UPPER FLOW AND INSTABILITY FOR UPDRAFTS TO BECOME STRONG ENOUGH FOR STORMS TO PERSIST OR BECOME SEVERE. EXPECT SHORT LIVED STORMS THAT PRODUCE SMALL HAIL...BRIEF GUSTY WINDS IN THE 30- 40 MPH RANGE AND QUICK MODERATE-LOCALLY HEAVY RAINFALL. SOME LOCALIZED FLOODING MAY BE POSSIBLE WEST OF THE BLUE RIDGE WHERE SHOWERS HAVE BEEN MORE PERSISTENT TODAY. UPPER LOW MOVES SOUTH OF THE REGION OVERNIGHT INTO FRIDAY AS A COASTAL LOW TAKES OVER OFF THE CAROLINAS. BOTH SYSTEMS COMBINED WILL INFLUENCE SENSIBLE WEATHER ELEMENTS INTO FRIDAY WITH OCCASIONAL SHOWERS...CLOUDY CONDITIONS. TEMPERATURES OVERNIGHT WILL DIP BACK INTO THE 40S IN MOST LOCATIONS EXCEPT 50S IN THE METRO CENTERS. READINGS WILL NOT RISE ALL THAT MUCH ON FRIDAY GIVEN ONSHORE FLOW AND CLOUD COVER. AFTERNOON HIGHS ONLY IN THE UPPER 50S TO LOWER 60S ARE EXPECTED. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... THE UPPER LOW AND SURFACE LOW WILL BE OFF THE NORFOLK COAST FRIDAY NIGHT. MOISTURE AND ISO SHOWERS WILL TAPER OFF WITH THE EXCEPTION OF THE POTOMAC HIGHLANDS. WEAK VORTICITY ADVECTION IS PROGGED ON THE BACK SIDE OF THE UPPER LOW AND A FEW SHOWERS WILL BE POSSIBLE OUT IN THE HIGHLANDS. FCST MIN TEMPS IN THE UPPER 40S LOW 50S EXPECTED FRIDAY NIGHT. HIGH PRESSURE WILL MOVE INTO THE MID-ATLANTIC SATURDAY. A SECONDARY TROUGH WILL SWING THROUGH THE REGION. COLD AIR ALOFT AND GOOD SFC HEATING WILL MAY PRODUCE A LITTLE INSTABILITY SATURDAY AFTERNOON. AS PVA MOVES INTO THE REGION ALONG THE TROUGH AXIS...SHOWERS MAY FORM ALONG AND EAST OF THE BLUE RIDGE MTNS AND SLOWLY TRACK EASTWARD. AT THIS TIME...COVERAGE SEEMS WEAK AND THEREFORE KEPT A CHANCE OF SHOWERS IN THE FORECAST. FCST MAX TEMPS IN THE UPPER 60S LOW 70S SATURDAY. LOSS OF DAYTIME HEATING WILL SURPRESS ANY SHOWER ACTIVITY SAT NIGHT. HIGH PRESSURE WILL MOVE OVERHEAD. FCST MIN TEMPS IN THE 40S AND LOW 50S EXPECTED. && .LONG TERM /SUNDAY THROUGH THURSDAY/... EXTENDED WARM-UP WITH SEVERAL DAYS OF HIGH TEMPS ABOVE CLIMO BEGINS SUN AND CONTINUES THROUGH MID WEEK...AS A RESULT OF HIGH PRESSURE AND CONTINUED RETURN FLOW INTO THE REGION. DEWPOINTS WILL ALSO BE INCREASING THROUGH THE PERIOD...WHICH WILL KEEP NIGHTTIME TEMPS U50S/L60S. PRECIP CHANCES VERY LOW THROUGH THE PERIOD...BUT COULD SEE UNSETTLED CONDITIONS RETURN WED ASSOCIATED WITH COLD FRONT THAT DROPS SOUTH AND STALLS NEAR OUR AREA. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE THIS AFTERNOON INTO THE EARLY EVENING HOURS. WILL MAINTAIN SHRA/TSRA MENTION IN THE TAFS. SOME OF THE STORMS WILL BE CAPABLE OF PRODUCING SMALL HAIL...GUSTY WINDS AND BRIEF DOWNPOURS. THUNDERSTORM POTENTIAL WILL WANE WITH SUNSET AND THE LOSS OF DAYTIME HEATING. LOW CLOUDS...OCCASIONAL SHOWERS/LIGHT RAIN WILL CONTINUE OVERNIGHT WITH A CHANCE FOR IFR CIGS AFTER MIDNIGHT INTO EARLY FRIDAY. CONDITIONS WILL GRADUALLY IMPROVE LATER FRIDAY AS LOW PRESSURE PULLS AWAY FROM THE REGION. VFR CONDITIONS EXPECTED FRI NIGHT THROUGH SATURDAY. -SHRA POSSIBLE SATURDAY AFTERNOON BUT COVERAGE IS UNCERTAIN AT THIS TIME AND WILL LIKELY BE ALONG THE HIGHER TERRAIN. VFR CONDITIONS EXPECTED SUN AND MONDAY. && .MARINE... NORTHEAST WINDS WILL INCREASE LATER THIS EVENING INTO THE OVERNIGHT HOURS AS LOW PRESSURE DEEPENS OFF THE CAROLINAS. SCA CONDITIONS ARE LIKELY OVERNIGHT INTO FRIDAY WITH GUSTS OVER 20 KTS EXPECTED. SCA CONDITIONS ARE POSSIBLE GOING INTO FRIDAY NIGHT BUT UNCERTAINITY EXISTS WITH THE PLACEMENT OF THE SFC LOW AT THAT TIME. N-NE 10-15 KT WILL CONTINUE ON THE WATERS AND WEAKEN BY SATURDAY MORNING. POSSIBILITY OF SCA LATE MONDAY...ESPECIALLY OVER THE SOUTHERN WATERS. && .TIDES/COASTAL FLOODING... A NORTHEAST WIND WILL INCREASE TONIGHT...THIS WILL KEEP WATER LEVELS ELEVATED BUT THE NORTHERLY COMPONENT WILL LIKELY KEEP ANOMALIES LOW ENOUGH SO WATER LEVELS REMAIN BELOW MINOR FLOODING THRESHOLDS WITH THE HIGH TIDE CYCLE LATE TONIGHT INTO FRIDAY MORNING. WINDS WILL SHIFT INTO NORTHERLY LATER FRIDAY WHICH IS NOT A FAVORABLE DIRECTION FOR FLOODING. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO NOON EDT FRIDAY FOR ANZ530-531-535-538-539. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM EDT FRIDAY FOR ANZ532>534-536-537-540>543. && $$ SYNOPSIS...HAS NEAR TERM...KRW SHORT TERM...HAS LONG TERM...MSE AVIATION...HAS/MSE/KRW MARINE...HAS/MSE/KRW TIDES/COASTAL FLOODING...KRW

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