Flash Flood Warning 45, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1222 PM EDT TUE AUG 12 2014

.SYNOPSIS...
LOW PRESSURE IS CENTERED OVER OHIO WITH A WARM FRONT EXTENDING
INTO THE CAROLINAS AND A COLD FRONT STRETCHING TO WEST TENNESSEE.
THE COLD FRONT WILL CROSS THE AREA EARLY WEDNESDAY MORNING. HIGH
PRESSURE WILL RETURN FOR THE SECOND HALF OF THE WEEK AND INTO THE
WEEKEND.

&&

.NEAR TERM /UNTIL 9 PM THIS EVENING/...
SYNOPTIC PTTN HAS CHGD LTL SINCE ELY THIS MRNG. HIGH PRESSURE
REMAINED OFF THE NEW ENGLAND/MID ATLC COASTS THIS MRNG...ALLOWING
A MOIST SOUTHEAST FLOW ACROSS THE CWA. MEANWHILE...FRONTAL
BOUNDARY OVER THE CAROLINAS WAS SNAKING ITS WAY BACK UP THE
APPALACHIANS AND INTO LOW PRESSURE OVER THE LOWER GREAT LAKES.

TO THE NORTH OF THIS BOUNDARY...ISENTROPIC LIFT/OVERRUNNING MOISTURE
WAS PRODUCING WAVES OF SHOWERS ACROSS THE REGION AS SHOWN BY
REGIONAL MOSAIC RADAR. A MORE SOLID ROUND OF SHRA ACRS CWFA ATTM
WITHIN A CONVEYOR OF HIGH PRECIPITABLE WATER/HIGH THETA-E AIR.

HIGH PW/S PROMOTING HEAVY RAINFALL ATTM. FFG RATHER HIGH FOR MOST
AREAS...BUT RAINFALL RATES HIGH AS WELL. CELLS HV BEEN TRAINING...
AND RADAR HAS BEEN UNDERESTIMATING THREAT. FLASH FLOOD WATCH HAS
BEEN POSTED FOR I-95 CRRDR WHERE GROUND HAS BEEN PRIMED.

SINCE PLUME OF RAFL HAS BEEN PERSISTENT...ITS INHIBITING CNVCTV
THREAT. STILL CANT RULE OUT EMBEDDED LOW-TOPPED TSRA...WHICH CUD
RESEMBLE TROPICAL CHARACTERISTICS. DMGG WND THREAT STILL NON-ZERO.

BOTH GFS AND NAM SUGGEST A WAVE OF LOW PRESSURE ALONG THE FRONT THIS
EVENING...WHICH WOULD TEND TO SLOW DOWN ITS EASTWARD PROGRESS. THUS
CONVECTION MAY CONTINUE WELL INTO THE EVENING. BUT EVENTUALLY THE
COLD FRONT WILL MOVE THROUGH AND WEST/NORTHWEST WINDS BEHIND THE
FRONT WILL PROMOTE DRYING AND A DECREASING TREND IN POPS OVERNIGHT.

FCST TEMPS MATCH UP WELL W/ LAMP...AND NO CHGS ANTICIPATED. TODAY/S
MAXIMA WERE DERIVED FROM A BLEND OF BIAS CORRECTED SREFS/ADJMAV...
FAVORING BELOW NORMAL UNDER CLOUDS/FREQUENT SHOWERS AND SOUTHEAST
FLOW. ADJMET HAS PERFORMED VERY WELL LATELY AND WAS USED FOR
MINIMA.

&&

.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
CWA WILL BE POST-FRONTAL WEDNESDAY...BUT UPPER TROUGH AXIS STILL HAS
TO PASS THROUGH. THIS COMBINED WITH COOLER AIR ALOFT WILL RESULT IN
SOME CLOUDS BUT CWA SHOULD BE DRY SAVE FOR A FEW SHOWERS ACROSS THE
POTOMAC HIGHLANDS...MAINLY THE WESTERNS SLOPES.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
WE HV A VERY COMPLEX NEXT 36 HRS IN THE MID ATLC...BUT AFTR THAT
THINGS SHOULD BE CALMING DOWN NICELY. THE CD FNT SHOLD BE WELL E
OF THE AREA WED NGT. A PRES GRAD COULD PERSIST WED NGT KEEPING IT
BRZY...OR DECOUPLING COULD OCCUR AND WINDS GO LGT. OUTSIDE OF THE
CITIES/ALONG THE BAY LOWS WL BE IN THE 50S WED NGT.

NO PROBS FORESEEN THU/FRI OR INTO THE WKND. HIGH PRES OVR THE
AREA. XPCT TO SEE A GRADUAL WARMUP: L80S TO END THE WORKWK THEN
CLIMBING INTO THE MU80S SUN.

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
ROUND OF SHRA W/ MDT-BRIEF HVY RA CROSSING METROS ATTM. MADE SOME
ADJUSTMENTS FOR BRIEF IFR.

AFTER A RELATIVE LULL...THUNDERSTORMS THEN ARE POSSIBLE THIS
AFTERNOON/EARLY EVENING AND ADDRESSED WITH VCTS IN THE TAFS. FRONT
WILL MOVE THROUGH OVERNIGHT WITH A WIND SHIFT TO WEST/NORTHWEST.
THIS SHOULD PRECLUDE FOG FORMATION OVERNIGHT. VFR EXPECTED
WEDNESDAY.

VFR CONDS XPCTD WED NGT STRAIGHT THRU TO THE WKND.

&&

.MARINE...
SE FLOW BCMG SLY TDA. HV NMRS SITES AT OR NEAR SCA CRIT ATTM...AND
WNDS PROGGED TO INCR. SCA IN EFFECT ALL WATERS REST OF TDA.

DVLPG THUNDERSTORMS LATER THIS AFTERNOON/EVENING COULD ALSO PRODUCE
STRONG GUSTY WINDS. ANTICIPATE SOME SPECIAL MARINE WRNGS MAY NEED
TO BE ISSUED.

COLD FRONT MOVES THROUGH OVERNIGHT. NOT SURE HOW STRONG THE NW
PUSH IS BEHIND THE FRONT FOR WEDNESDAY. CAN/T RULE OUT A SCA
BECOMING NECESSARY BUT CONFIDENCE TOO LOW ATTM.

IN THE XTND PD...PRIMARILY A CALM PD ON THE WATERS. IT IS PSBLTHAT
SCA LVL GUSTS MAY CONT ON THE BAY...BUT THU AND FRI LOOKING LK
GOOD DAYS TO BE ON THE WATERS. AS OF NOW THIS TREND IS XPCTD TO
CONT INTO THE WKND.

&&

.TIDES/COASTAL FLOODING...
ANOMALIES REMAIN AROUND 1 FT AS OF 8AM. WITH SOUTHEAST FLOW THIS
MORNING...THEN SOUTHERLY FLOW THIS AFTERNOON ANOMALIES MAY
INCREASE TODAY. SO EVEN THOUGH THE PM TIDE IS A LITTLE LOWER
ASTRONOMICALLY...SUSPECT THE RESULTS WILL BE ABOUT THE SAME. IN
ADDITION...CBOFS WATER LEVEL ANIMATION SUGGESTS WATER WILL PILE
AROUND THE MOUTH OF THE SUSQUEHANNA AS WELL...SO HAVRE DE GRACE
SHOULD SEE SOME IMPACTS BY TONIGHT. WITH THIS IN MIND...HAVE
EXTENDED ADVY TO INCLUDE THE AFTN/EVE TIDE CYCLE. PRINCE GEORGES
CNTY HAS BEEN ADDED BASED ON SURVEY WORK. ANY INUNDATION WOULD BE
HIGHLY LOCALIZED NUSAINCE/MINOR.

BLOWOUT NWLY WINDS WILL BE ARRIVING AT THE SAME TIME AS THE AM
TIDE CYCLE. IT WILL BE A CLOSE CALL. AT THIS POINT...CANNOT RULE
OUT A FEW SITES BEING AFFECTED ONE MORE TIME ELY WED MORNING...
MAINLY ANNAPOLIS SOUTH.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR DCZ001.
     COASTAL FLOOD ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR DCZ001.
MD...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR MDZ005>007-009>011-
     013-014-016.
     COASTAL FLOOD ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR MDZ007-011-
     013.
     COASTAL FLOOD ADVISORY UNTIL 10 PM EDT THIS EVENING FOR MDZ014-
     017-018.
VA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR VAZ052>057.
     COASTAL FLOOD ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR VAZ054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ532>534-
     537-540>543.
     SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ530-
     531-535-536-538-539.

&&

SYNOPSIS...
NEAR TERM...HTS/BPP
SHORT TERM...BPP
LONG TERM...WOODY!
AVIATION...HTS/BPP/WOODY!
MARINE...HTS/BPP/WOODY!
TIDES/COASTAL FLOODING...HTS

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1216 PM EDT TUE AUG 12 2014

ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057-
130930-
CHESAPEAKE BAY NORTH OF POOLES ISLAND MD-
CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD-
CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD-
CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD-
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA-
TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD-
TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD-
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA-
PATAPSCO RIVER INCLUDING BALTIMORE HARBOR-
CHESTER RIVER TO QUEENSTOWN MD-EASTERN BAY-
CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER-
PATUXENT RIVER TO BROOMES ISLAND MD-
TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH
ISLAND-DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD-
SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-
CALVERT-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-
1216 PM EDT TUE AUG 12 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE
CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN
CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF
COLUMBIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A FLASH FLOOD WATCH IS IN EFFECT UNTIL LATE TONIGHT FOR PORTIONS
OF MARYLAND...THE DISTRICT OF COLUMBIA AND VIRGINIA. PERIODS OF SHOWERS
AND THUNDERSTORMS WITH AREAS OF HEAVY RAINFALL WILL BE POSSIBLE
WHICH MAY RESULT IN POTENTIAL FLOODING ALONG THE INTERSTATE 95
CORRIDOR.

SOME THUNDERSTORMS DURING THE LATE AFTERNOON AND EVENING MAY
ALSO PRODUCE DAMAGING WIND GUSTS. AN ISOLATED TORNADO IS ALSO
POSSIBLE.

A COASTAL FLOOD ADVISORY IS IN EFFECT FOR THE WESTERN SHORE OF THE
MARYLAND CHESAPEAKE BAY AND ALONG THE UPPER TIDAL POTOMAC RIVER
THROUGH THE HIGH TIDE CYCLE THIS AFTERNOON AND EVENING. TIDAL
FLOODING MAY LINGER INTO PREDAWN WEDNESDAY MORNING FOR SAINT
MARYS...CALVERT...AND ANNE ARUNDEL COUNTIES.

A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE MARYLAND
CHESAPEAKE BAY AND TIDAL POTOMAC RIVER TODAY. THE SMALL CRAFT
ADVISORY CONTINUES OVER A PORTION OF THE WATERS THIS EVENING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

A SMALL CRAFT ADVISORY MAY BE NECESSARY OVER A PORTION OF THE
WATERS WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504-
WVZ050>053-055-501>506-130930-
WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-AUGUSTA-
ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-NELSON-
ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-ORANGE-CULPEPER-
NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND-
EASTERN HIGHLAND-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-HARDY-
WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-
WESTERN PENDLETON-EASTERN PENDLETON-
1216 PM EDT TUE AUG 12 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA...
NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND
WITH THE EXCEPTION OF GARRETT COUNTY.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A FLASH FLOOD WATCH IS IN EFFECT UNTIL LATE TONIGHT FOR PORTIONS
OF MARYLAND...THE DISTRICT OF COLUMBIA AND VIRGINIA. PERIODS OF SHOWERS
AND THUNDERSTORMS WITH AREAS OF HEAVY RAINFALL WILL BE POSSIBLE
WHICH MAY RESULT IN POTENTIAL FLOODING PRIMARILY EAST OF THE BLUE
RIDGE AND ACROSS THE INTERSTATE 95 CORRIDOR.

SOME THUNDERSTORMS DURING THE AFTERNOON AND EVENING MAY ALSO PRODUCE
DAMAGING WIND GUSTS. AN ISOLATED TORNADO IS ALSO POSSIBLE.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
154 PM EDT TUE AUG 12 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1245 PM     FLASH FLOOD      1 ESE LAUREL            39.10N  76.85W
08/12/2014                   PRINCE GEORGES     MD   BROADCAST MEDIA

            WATER UP TO THE HEADLIGHTS OF CARS OFF BOWIE ROAD EAST
            OF ROUTE 1. ROAD CLOSED.

&&

EVENT NUMBER LWX1400922

JE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
221 PM EDT TUE AUG 12 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0158 PM     FLASH FLOOD      BWI AIRPORT             39.17N  76.67W
08/12/2014                   ANNE ARUNDEL       MD   PUBLIC

            WATER FLOWING OVER ROADWAYS AND UP TO THE HEADLIGHTS OF
            CARS NEAR BWI AIRPORT.

&&

EVENT NUMBER LWX1400923

JE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
224 PM EDT TUE AUG 12 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0157 PM     FLASH FLOOD      BWI AIRPORT             39.17N  76.67W
08/12/2014                   ANNE ARUNDEL       MD   PUBLIC

            FLOODING REPORTED AT THE MAINTENANCE SHOP AT BWI.

&&

EVENT NUMBER LWX1400924

JE