Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 240753 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 353 AM EDT THU JUL 24 2014 .SYNOPSIS...
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A COLD FRONT WILL SLOWLY PASS THROUGH THE AREA TODAY. HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT THROUGH FRIDAY BEFORE MOVING OFF THE COAST DURING THE WEEKEND. A COLD FRONT WILL PASS THROUGH THE AREA EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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UNLIKE MOST COLD FRONTAL PASSAGES...ANOTHER SECONDARY WAVE OF MOISTURE IS MOVING THRU BEHIND THE BOUNDARY HERE IN THE OVERNIGHT PERIOD. THE COLD FRONT ITSELF IS MORE OF A WEAK SFC WIND SHIFT W/ VERY LITTLE AIRMASS CHANCE BEHIND IT OTHER THAN COOLER TEMPS. THE STRENGTH OF THE COLDER/DRIER AIRMASS IS IN TWO SEPARATE UPPER WAVES. THE FIRST IS STILL BACK ACROSS THE UPPER MIDWEST...AND THE SECOND IS ABOUT A TIER OF STATES FURTHER BACK TO THE NORTH. EACH OF THESE WILL EVENTUALLY SWEEP REINFORCING COOLER AIR AND SUBSIDENCE DOWN FROM THE NW...BUT THE MOIST AND GENERALLY UNSTABLE AIR WILL REMAIN SOUTH OF THE MASON-DIXON LINE OVER THE NEXT SEVERAL HRS. SCATTERED SHOWERS STILL LINGERING OVER MUCH OF THE AREA...THOUGH THE CWA HAS BEEN LARGELY DRY BEHIND THE CONVECTIVE LINE LATE LAST EVENING. THE I-95 CORRIDOR WILL BE RECEIVING SOME OF THIS SLOW-MOVING SHOWER ACTIVITY INTO THE PREDAWN HRS. EMBEDDED AREAS OF MODERATE TO HEAVY SHOWERS WILL MOVE ACROSS THE REGION...BUT MOST LOCALES WILL JUST SEE SOME LIGHT RAIN IN THE COMING HRS. AS THE SHOWERS MOVE EAST...THE FIRST UPPER WAVE WILL BEGIN TO PUSH INTO THE NRN HALF OF THE CWA AND DRY THE AREA OUT. THE SRN HALF...CLOSER TO THE LEFTOVER SFC BOUNDARY - WILL CONTINUE TO SEE SHOWERS AND ISOLATED WEAK CONVECTION DEVELOP THROUGHOUT THE DAY. ONLY INTO THE EVE HRS WILL PRECIP CHANCES BEGIN TO SUBSIDE ALONG AND SOUTH OF THE I-66 CORRIDOR. A SOLID NLY BREEZE WILL COME OVER THE ERN HALF OF THE CWA...W/ THE DRY AND COOL FLOW PUSHING ACROSS THE BALT/DC AREA LATER THIS AFTN. TEMPS WILL STILL MAKE IT INTO THE L-M80S ACROSS THE AREA FOR DAYTIME HIGHS...BUT DEWPOINTS WILL HOVER IN THE M50S OR LOWER THIS AFTN WHICH IS A NOTICEABLY LESS HUMID FEEL TO THE AIR THAN THE PAST COUPLE OF DAYS. THE NEAR-10 DEG DROP IN DEWPOINTS WILL REFLECT IN THE OVERNIGHT LOWS AS WELL ON THU NIGHT/FRI MRNG. TEMPS ACROSS THE NRN HALF WILL DROP TO THE L60S AND SOME U50S...WHILE THE I-95 CORRIDOR AND AREAS SOUTH/EAST WILL SEE LOWS IN THE L-M60S.
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&& .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
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A WEAK UPPER-LEVEL TROUGH WILL REMAIN OVERHEAD FRIDAY. HOWEVER...SURFACE HIGH PRESSURE WILL ALSO BE OVERHEAD SO DRY CONDITIONS ARE EXPECTED ALONG WITH SUNSHINE. A SCT/BKN CU DECK WILL DEVELOP DURING THE AFTERNOON. MAX TEMPS WILL RANGE FROM THE UPPER 60S AND LOWER 70S IN THE MOUNTAINS TO THE LOWER AND MIDDLE 80S ACROSS MOST OTHER LOCATIONS. DEWPOINTS IN THE 50S AND 60S WILL ALSO MAKE IT FEEL NOTICEABLY LESS HUMID COMPARED TO RECENT DAYS. HIGH PRESSURE WILL REMAIN OVERHEAD FRIDAY NIGHT...BRINGING DRY AND COMFORTABLE CONDITIONS.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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HIGH PRESSURE WILL MOVE OFF THE COAST SATURDAY AND A RETURN SOUTHERLY FLOW WILL USHER IN WARMER AND A BIT MORE HUMID CONDITIONS. THE INCREASED HEAT AND HUMIDITY MAY LEAD TO A COUPLE SHOWERS AND THUNDERSTORMS...BUT COVERAGE SHOULD REMAIN ISOLATED TO WIDELY SCATTERED DUE TO THE LACK OF A STRONG LIFTING MECHANISM. A POTENT COLD FRONT WILL MOVE THROUGH THE GREAT LAKES SUNDAY AND THIS WILL CARVE OUT A TROUGH OF LOW PRESSURE BOTH AT THE UPPER- LEVELS AND LOWER-LEVELS OF THE ATMOSPHERE ACROSS OUR AREA. A SOUTHERLY FLOW AROUND HIGH PRESSURE OFF THE ATLANTIC WILL CONTINUE TO USHER IN WARM AND HUMID CONDITIONS. THE INCREASED FORCING ALONG WITH THE HEAT AND HUMIDITY WILL LEAD TO A BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL PASS THROUGH THE AREA MONDAY...BRINGING THE CHANCE FOR MORE SHOWERS AND THUNDERSTORMS. NOTICEABLY COOLER AND DRIER CONDITIONS ARE EXPECTED BEHIND THE FRONT FOR THE MIDDLE PORTION OF NEXT WEEK.
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&& .AVIATION /07Z THURSDAY THROUGH MONDAY/...
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SCATTERED SHOWERS NOW SLIDING FROM WEST-TO-EAST ACROSS THE MID ATLC AND NOW REACHING THE DC/BALT METRO AREAS TOWARD THE PREDAWN HRS. ONLY ISOLATED HEAVIER SHOWERS AND THE TWO MAIN CLOUD DECKS ARE ROUGHLY 5KFT AND 10KFT...W/ THE HIGHER ONE BEING THE PREDOMINANT ONE. ONLY THE KCHO AREA WILL SEE THE LOWERED CIGS/VSBYS THROUGHOUT THE DAY AND W/ MORE PRECIP CHANCES UNTIL LATER THIS EVE. A COLD FRONT SAGGING SOUTH ACROSS THE AREA WILL SLOWLY USHER-IN A STIFF NW-NLY BREEZE LATER THIS MRNG. THIS WILL AFFECT AREAS ALONG THE I-95 CORRIDOR AND EAST W/ A GENERAL N WIND NEAR 10KT. PRECIP WILL DECREASE THROUGHOUT THE DAY AND INTO TONIGHT W/ CLEARING SKIES AND LIGHT WINDS TOWARD FRI MRNG. HIGH PRESSURE WILL BRING VFR CONDITIONS FOR FRIDAY THROUGH FRIDAY EVENING. PATCHY FOG IS EXPECTED LATE FRIDAY NIGHT INTO SATURDAY MORNING. A SOUTHERLY FLOW WILL DEVELOP FOR SATURDAY AND SUNDAY AS HIGH PRESSURE MOVES OFF THE COAST. THE INCREASED MOISTURE FROM THE SOUTHERLY FLOW WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. THUNDERSTORMS WILL BE MORE WIDESPREAD IN COVERAGE SUNDAY. A COLD FRONT FRONT WILL PASS THROUGH THE TERMINALS MONDAY...BRINGING THE CHANCE FOR MORE SHOWERS AND THUNDERSTORMS.
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&& .MARINE...
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BEHIND THE CONVECTIVE LINE...SOME SHOWERS WILL MOVE IN FROM THE WEST BUT WINDS WILL REMAIN LIGHT INTO THE EARLY MRNG. A COLD FRONT WILL PRECEDE A SEVERAL-HR PERIOD OF NLY FLOW...PUSHING A GENERAL 10-15KT WIND CHANNELING DOWN THE STEM OF THE MD BAY THIS AFTN/EVE. A BRIEF RESPITE AND THEN SOME MORE NLY CHANNELING OVERNIGHT...BUT EXPECTED TO BE NEAR BUT BELOW SCA RANGE. HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY INTO FRIDAY NIGHT. THE HIGH WILL MOVE OFF THE COAST SATURDAY AND SUNDAY...ALLOWING FOR A SOUTHERLY FLOW TO DEVELOP. SOUTHERLY WINDS MAY GUST PAST SCA CRITERIA FOR PORTIONS OF THE WATERS SATURDAY AFTERNOON THROUGH SUNDAY MORNING. A POTENT COLD FRONT WILL PASS THROUGH THE WATERS EARLY NEXT WEEK. SHOWERS AND THUNDERSTORMS ARE POSSIBLE SATURDAY THROUGH MONDAY. AS OF NOW IT APPEARS THAT THE MOST WIDESPREAD COVERAGE IN THUNDERSTORMS WILL BE SUNDAY INTO SUNDAY NIGHT...BUT CERTAINTY REMAINS LOW THIS FAR OUT.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BJL NEAR TERM...GMS SHORT TERM...BJL LONG TERM...BJL AVIATION...BJL/GMS MARINE...BJL/GMS

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