Severe Thunderstorm Warning 87, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
301 PM EDT MON JUN 15 2015

.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHEAST WILL REMAIN IN CONTROL THROUGH
TUESDAY. A COLD FRONT WILL MOVE IN FROM THE NORTHWEST ON TUESDAY
NIGHT AND STALL OUT IN OUR AREA WEDNESDAY. IT WILL BRIEFLY MOVE
BACK NORTH AS A WARM FRONT ON THURSDAY BEFORE COMING BACK SOUTH ON
THURSDAY NIGHT AS A COLD FRONT...AND THEN MOVE BACK NORTH AS A
WARM FRONT AGAIN ON SATURDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
LATEST ANALYSIS PUTS OUR REGION ON THE WARM SIDE OF A FRONTAL
BOUNDARY EXTENDING FROM NEAR NEW YORK CITY NORTHWEST TO SOUTHERN
ONTARIO, THEN WEST INTO WISCONSIN AND SOUTHWEST TO EASTERN
COLORADO. SEVERAL WAVES OF LOW PRESSURE ARE LOCATED ALONG THIS
FRONT BUT THEY ARE ALL PRETTY WEAK. HIGH PRESSURE REIGNS TO THE
SOUTH OF THIS FRONT...THOUGH IT IS ALSO PRETTY WEAK AT THE
SURFACE. ALOFT HOWEVER...A CONSIDERABLY STRONGER RIDGE IS PRESENT
OVER THE SOUTHEAST AND WE ARE ON ITS NORTHERN PERIPHERY.
SHORTWAVES ARE ROTATING AROUND IT...WITH A VERY WEAK ONE CURRENTLY
OVER WEST VIRGINIA AND PENNSYLVANIA WITH A CONSIDERABLY STRONGER
ONE LOCATED OVER THE GREAT LAKES AND CENTRAL PLAINS.

OVER THE NEXT 24 HOURS...THE SHORTWAVE NEARBY WILL QUICKLY MOVE
EAST THIS EVENING...BUT THE STRONGER SHORTWAVE WILL APPROACH FROM
THE MIDWEST AND REACH US LATE TUESDAY BEFORE WASHING OUT TUESDAY
NIGHT. THIS SHORTWAVE WILL BE ACCOMPANIED BY THE FRONTAL BOUNDARY
TO OUR NORTHWEST. IN ASSOCIATION WITH THE WEAK SHORTWAVE THIS
EVENING...THE EXISTING VERY MOIST ATMOSPHERE (PW'S NEAR 2") AND
LIMITED INSOLATION REACHING THE SURFACE THROUGH THE PERSISTENT
CLOUDS SHOULD ALLOW SOME SHOWERS AND THUNDERSTORMS TO MAINTAIN
THEMSELVES AS THEY MOVE IN FROM THE WEST. GIVEN THE LIMITED CAPE
THANKS TO THE CLOUDS TODAY...AND MEDIOCRE MID-LEVEL LAPSE
RATES...THINK THE RISK OF SEVERE IS PRETTY LOW...BUT AN ISOLATED
DAMAGING WIND GUST IS NOT OUT OF THE QUESTION. ALSO...GIVEN THE
AFOREMENTIONED HIGH PW'S...SOME LOCALLY HEAVY RAIN IS
POSSIBLE...AND SHOULD SOME STORMS START TO TRAIN...A FLASH FLOOD
WARNING OR TWO CAN'T BE RULED OUT. AFTER THE PASSAGE OF THE
SHORTWAVE THIS EVENING MOST SHOWERS AND STORMS SHOULD MOVE AWAY
AND/OR DIE OUT...BUT CLOUDS SHOULD LINGER HERE ON THE NORTHERN
EDGE OF THE RIDGE. WE WILL REMAIN VERY WARM OVERNIGHT WITH MANY
LOCALES IN THE 70S. PATCHY FOG MAY OCCUR IN THE SHELTERED MOUNTAIN
VALLEYS BUT DON'T EXPECT MUCH GIVEN CLOUDS.

OF SLIGHTLY MORE INTEREST IS THE STRONGER SHORTWAVE APPROACHING
FROM THE WEST ON TUESDAY...ACCOMPANIED BY THE SURFACE COLD FRONT.
WINDS ALOFT INCREASE WITH THIS...SHEAR MAKES A NOTICEABLE
UPTICK...BUT MID-LEVEL LAPSE RATES REMAIN WEAK AND WE MAY AGAIN
HAVE TO DEAL WITH LINGERING CLOUDS THROUGH MOST OF THE DAY WHICH
WOULD LIMIT CAPE. EXPECT MORE SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS BY LATE IN THE DAY...BUT AGAIN THE CAPE QUESTION
MAKES ONE WONDER JUST HOW MUCH SEVERE THERE WILL BE. THINK THE
ODDS ARE A BIT BETTER THAN TODAY...BUT PROBABLY NOT ENOUGH TO
WARRANT A SLIGHT RISK AND SPC HAS DOWNGRADED US TO MARGINAL FOR
TUESDAY AS WELL. DESPITE THE CLOUDS MOST AREAS WILL ONCE AGAIN
FLIRT WITH 90. WINDS AHEAD OF THE FRONT WILL INCREASE AND IT WILL
BE NOTICEABLY BREEZY IN THE AFTERNOON.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
UPPER LEVEL RIDGE CONTINUES ACROSS THE GULF COAST STATES AS SFC
HIGH PRESSURE DRAWS HUMID AIR INTO THE MID-ATLANTIC. A FRONTAL
BOUNDARY WILL MOVE INTO THE NRN MID-ATLANTIC TUESDAY NIGHT
SURPRESSING THE HUMID AIRMASS TO THE SOUTH. ANY SHOWERS AND
THUNDERSTORMS TUESDAY AFTERNOON SHOULD DIMINISH TUESDAY EVENING
WITH THE LOSS OF DAYTIME HEATING AND LITTLE FORCING. THE FRONTAL
BOUNDARY WILL STALL ACROSS THE REGION WEDNESDAY. N WINDS WILL DRAW
SOME DRIER AIR INTO THE NRN MID-ATLANTIC WITH DEWPTS IN THE 50S.
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ON THE WARM SIDE OF THE
BOUNDARY WEDNESDAY LATE MORNING EARLY AFTERNOON MAINLY ACROSS
AREAS WEST OF THE BLUE RIDGE AND SOUTH OF I-50 IN VA. THE FRONTAL
BOUNDARY WILL LIKELY RETREAT AS A WARM FRONT WEDNESDAY NIGHT AND
ACTIVITY WILL SPREAD N-E. AN AREA OF LOW PRESSURE MAY ALSO MOVE
NEAR THE REGION WEDNESDAY NIGHT. THE POTENTIAL FOR HEAVY RAIN
EXISTS NEAR THE MD/PA BORDER WEDNESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
RIDGING WILL REMAIN STATIONED OFF THE SOUTHEASTERN CONUS LATE
THIS WEEK AND INTO THE WEEKEND KEEPING A VERY WARM TO HOT AND
HUMID AIRMASS OVER THE REGION. GFS/GEFS TRYING TO PRINT OUT A QPF
BULLS EYE OVER NORTHERN PARTS OF THE AREA FIRST THING THURSDAY
MORNING...BUT BELIEVE THIS MAY BE OVERDONE GIVEN LACK OF SHEAR AND
UNFAVORABLE TIME OF DAY FOR MORE ORGANIZED WIDESPREAD CONVECTION.
SO KEPT POPS AT CHANCE FOR NOW.

BOUTS OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ARE
POSSIBLE PRETTY MUCH EVERY DAY THROUGH THE WEEKEND DURING PEAK
HEATING AS THE AREA REMAINS SANDWICHED BETWEEN RIDGING TO THE
SOUTH AND WESTERLIES TO THE NORTH. A TYPICAL SUMMERTIME PATTERN
FOR OUR AREA.

MORE ORGANIZED SHOWERS AND THUNDERSTORMS ARE POSSIBLE LATER IN
THE WEEKEND AS A FRONTAL SYSTEM APPROACHES.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
OVERALL VFR CIGS AND VIS THRU THE PERIOD. SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EVENING...AGAIN TUESDAY AFTERNOON
AND EVENING...AND AT DIFFERENT PERIODS THROUGH THE LONGER
TERM...MAY BRING BRIEF SUB-VFR VISIBILITY...AND STORMS THIS
AFTERNOON AND AGAIN TUESDAY MAY PRODUCE ISOLATED DAMAGING WIND
GUSTS OR LARGE HAIL. WINDS WILL REMAIN FAIRLY LIGHT FROM THE
SOUTHWEST TODAY BUT INCREASE AHEAD OF THE FRONT ON TUESDAY
AFTERNOON WITH GUSTS EXPECTED TO EXCEED 20 KNOTS. N WINDS TUESDAY
EVENING BECOME EASTERLY BY WEDNESDAY NIGHT...THEN GENERALLY SWLY
FLOW THU-FRI...THEN NLY FRI 10 KT OR LESS.

&&

.MARINE...
SUB-SCA CONDITIONS OVERALL THROUGH TUESDAY MORNING...BUT MARINERS
SHOULD KEEP AN EYE ON POTENTIAL FOR SPECIAL MARINE WARNINGS DUE TO
SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING. TUESDAY THE
WINDS INCREASE FROM THE SOUTHWEST AS A FRONT APPROACHES...AND HAVE
RAISED SMALL CRAFT ADVISORIES FOR ALL WATERS WITH GUSTS IN MOST
AREAS EXPECTED TO EXCEED 18 KNOTS. ONCE AGAIN...THE RISK OF
STRONG THUNDERSTORMS COULD RESULT IN MORE SPECIAL MARINE WARNINGS.
NORTH WINDS BEHIND THE FRONT LATER TUESDAY NIGHT WILL BECOME
EASTERLY BY WEDNESDAY NIGHT AND SOUTHWESTERLY LATE IN THE
WEEK...BUT RIGHT NOW LOOKS LIKE THE PRESSURE GRADIENT SHOULD
REMAIN WEAK ENOUGH TO KEEP WINDS BELOW SCA LEVELS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TO 10 PM EDT TUESDAY FOR
     ANZ530>543.

&&

SYNOPSIS...RCM
NEAR TERM...RCM
SHORT TERM...HAS
LONG TERM...DFH
AVIATION...HAS/RCM/DFH
MARINE...HAS/RCM/DFH

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