Special Weather Statement, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
311 PM EDT SUN SEP 2 2012

.SYNOPSIS...
A STATIONARY FRONT WILL PERSIST OVER THE CENTRAL MID ATLANTIC
THROUGH TONIGHT...THEN LIFT NORTH AS A WARM FRONT ON MONDAY.
MEANWHILE...REMNANTS OF ISAAC WILL CONTINUE DRIFTING EAST FROM THE
MIDWEST THROUGH TUESDAY NIGHT. AN UPPER TROUGH LOOKS TO CONTINUE THE
ACTIVE WEATHER PERIOD INTO THURSDAY BEFORE A COLD FRONT CROSSES THE
REGION LATE THURSDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
WEAK FRONTAL BOUNDARY REMAINS STALLED ACROSS NORTH CENTRAL VIRGINIA
THIS AFTERNOON. SEVERAL PIECES OF MID LEVEL SHORTWAVE ENERGY WILL
MOVE ALONG THE BOUNDARY THIS AFTERNOON AND EARLY EVENING...EACH
ENHANCING THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS.

12Z SOUNDING ANALYSIS SHOWS A VERY MOIST AIRMASS IN PLACE WITH PWATS
AROUND 2 INCHES. THIS IS SLIGHTLY UNDER TWO STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR...HOWEVER PWATS ARE FORECAST TO
INCREASE OVERNIGHT AND MONDAY TO NEAR THE TWO STANDARD DEVIATION
MARK. BOUNDARY LAYER WINDS ARE 15 KT OR LESS...SO WITH THE SLOW
MOVEMENT AND TRAINING OF ANY STORMS...LOCALIZED FLASH FLOODING IS
POSSIBLE TODAY. ACROSS THE SOUTHERN TWO TIERS OF ZONES...THE CLOUDS
HAVE BEGUN TO MIX OUT. THESE AREAS WILL CONTINUE TO DESTABILIZE
THROUGH SUNSET WITH THE POTENTIAL FOR BETWEEN ONE AND TWO THOUSAND
JULES OF CAPE THIS AFTERNOON. MID LEVEL LAPSE RATES AND 0-6KM SHEAR
ARE NOT IMPRESSIVE...BUT A FEW STORMS COULD PRODUCE DAMAGING WIND
GUSTS. WET BULB ZERO/FREEZING LEVEL HEIGHTS ARE A FEW THOUSAND FEET
ABOVE YESTERDAY'S VALUES...SO WIND WILL BE MORE LIKELY THAN HAIL.

CURRENT RADAR TRENDS HAVE AN AREA OF SHOWERS ALONG THE FRONTAL
BOUNDARY...WITH THUNDERSTORMS DEVELOPING IN THE WARM SECTOR. THIS
TREND WILL CONTINUE THROUGH THE EARLY EVENING HOURS. 12Z MODELS WERE
CONSISTENT IN HAVING A BREAK IN THE WIDESPREAD PRECIP OVERNIGHT...SO
HAVE REDUCED POPS TO CHANCE AFTER 00Z.

WIDESPREAD PRECIP IS EXPECTED TO DEVELOP ONCE AGAIN ACROSS THE CWFA
DURING THE DAY ON MONDAY. KEPT THE LIKELY POPS IN PLACE. LOCALIZED
FLASH FLOODING IS POSSIBLE OVERNIGHT AND TOMORROW AS THE SOILS
CONTINUE TO SATURATE.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
THE REMNANTS OF ISAAC ARE EXPECTED TO CONTINUE AFFECTING THE MID
ATLANTIC INTO WEDNESDAY...CONTINUING PERIODIC HEAVY SHOWERS AND
THUNDERSTORMS. FLASH FLOODING IS POSSIBLE THROUGH THE SHORT TERM.

MONDAY NIGHT THROUGH TUESDAY NIGHT...REMNANTS OF ISAAC TRACK UP THE
OHIO VALLEY...WITH THE WARM FRONT AHEAD OF THIS LOW PERSISTING
AROUND THE MASON-DIXON LINE. LIKELY POPS SPREAD EAST THROUGH THIS
TIMEFRAME. PWATS WILL REMAIN AROUND 2.2 INCHES THROUGH THIS
TIME...SO HEAVY RAINFALL IS LIKELY AND A FLASH FLOOD THREAT WILL
ALSO REMAIN. TEMPERATURES A FEW DEGREES ABOVE NORMAL WILL PERSIST
FROM SLY SFC FLOW UNDER THICK CLOUDS.

WEDNESDAY...WEAK COLD FRONT IN THE WAKE OF THE EXTRA-TROPICAL ISAAC
REMNANTS CONTINUES LIKELY POPS...WITH PRECIP TAPERING OFF BEHIND THE
FRONT. HOWEVER...THIS REALLY IS NOT MUCH OF A COLD FRONT AS 16C 850
TEMPS BUILD IN BEHIND THE SYSTEM. IN FACT A WARMING TREND IS
EXPECTED FOR LATER IN THE WEEK...OWING MOSTLY TO INCREASED SUNSHINE.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
UPR TROUGH IN WAKE OF ISAAC REMNANTS CROSSES THE REGION THURSDAY.
WENT WITH CHANCE POPS FOR NOW...THOUGH CONSIDERING HOW
PRECONDITIONED THE SOIL WILL BE LIKELIES WILL PROBABLY BE ABLE TO BE
PUT IN SOON.

IN A LOOK AHEAD TO NEXT WEEKEND...HIGH PRESSURE IN THE WAKE OF THE
UPR TROUGH FRIDAY LOOKS TO BE SHORT LIVED AS A DEEPER TROUGH IS
PROGGED TO APPROACH THE MID ATLANTIC SATURDAY NIGHT/SUNDAY.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
A STATIONARY FRONT WILL REMAIN STATIONARY ACROSS NORTH CENTRAL
VIRGINIA THROUGH TONIGHT...BUT BEGIN SHIFTING NORTHWARD ON MONDAY.

MOST OF THE TERMINAL SITES WILL BE AFFECTED BY NUMEROUS/WIDESPREAD
SHOWERS AND THUNDERSTORMS THROUGH THE EVENING. ACTIVITY WILL BE MORE
SCATTERED IN NATURE ACROSS BWI AND MTN. PRECIP WILL BECOME MORE
WIDESPREAD DURING THE LATE MORNING AND EARLY AFTERNOON HOURS ON
MONDAY. SUB VFR VSBYS AT MOST TERMINAL SITES THIS AFTERNOON WITH
SHRA/TSRA AND AGAIN TOMORROW AFTERNOON.

MODELS ARE BRINGING IN SOME MVFR CIGS OVERNIGHT. THE LOWER CIGS
SHOULD BEGIN TO IMPROVE BY THE LATE MORNING.

ONGOING PRECIPITATION EVENT FROM THE REMNANTS OF ISAAC CONTINUES
MONDAY NIGHT THROUGH WEDNESDAY. SFC FLOW WILL MAINLY BE SLY WITH
MVFR/IFR CONDS EXPECTED IN THE SHRA/TSRA. MORE ACTIVE WEATHER
THURSDAY BEFORE BRIEF HIGH PRESSURE THEN INTO NEXT WEEKEND.

&&

.MARINE...
EAST/SOUTHEAST FLOW AOB 15 KT WILL CONTINUE ACROSS THE WATERS
THROUGH TOMORROW. NO HEADLINES ANTICIPATED...BUT A FEW SPECIAL
MARINE WARNINGS ARE POSSIBLE WITH GUSTY THUNDERSTORMS THROUGH THIS
EVENING.

A STATIONARY FRONT WILL REMAIN ACROSS THE BAY THROUGH TONIGHT BUT
BEGIN SHIFTING NORTHWARD DURING THE DAY TOMORROW.

SELY FLOW CONTINUES THROUGH TUESDAY NIGHT AS REMNANTS OF ISAAC
APPROACH FROM THE WEST. FLOW BECOMES SLY TUESDAY NIGHT AND CONTINUES
THROUGH MIDWEEK AS THE REMNANTS TRACK TO THE NORTH OF THE CHESAPEAKE
BAY. HEAVY SHOWERS AND THUNDERSTORMS PERSIST ACROSS THE WATERS
THROUGH WEDNESDAY.

&&

.TIDES/COASTAL FLOODING...
COASTAL FLOODING EXPECTED EVENTUALLY...
WATER LEVELS HAVE RAISED TO HALF A FOOT ABOVE ASTRONOMICAL
PREDICTION THIS AFTERNOON. DEPARTURES WILL CONTINUE TO RISE AND
WOULD HAVE TO INCREASE ABOVE THREE-QUARTERS OF A FOOT FOR
ANNAPOLIS TO REACH ITS MINOR THRESHOLD. LEVELS ARE EXPECTED TO
REMAIN BELOW MINOR THRESHOLDS FOR THIS EVENING.
HOWEVER...CONTINUED EASTERLY FLOW INCREASES SHOULD CAUSE MINOR
FLOODING FOR THE MONDAY HIGH TIDES. THE COASTAL FLOOD THREAT
CONTINUES THROUGH WEDNESDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

SYNOPSIS...BAJ/NWL
NEAR TERM...NWL
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/NWL
MARINE...BAJ/NWL
TIDES/COASTAL FLOODING...BAJ

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
334 PM EDT SUN SEP 2 2012

ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057-
031645-
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-
334 PM EDT SUN SEP 2 2012

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

THREATS FOR HEAVY RAINFALL AND LOCALIZED FLASH FLOODING CONTINUE
THIS AFTERNOON AND EVENING. ISOLATED THUNDERSTORMS COULD ALSO
PRODUCE LOCALLY DAMAGING WIND GUSTS THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

HEAVY RAINFALL COULD LEAD TO LOCALIZED FLASH FLOODING MONDAY
THROUGH TUESDAY.

MINOR COASTAL FLOODING IS LIKELY ALONG THE WESTERN SHORE OF THE
CHESAPEAKE BAY AND THE TIDAL POTOMAC RIVER MONDAY INTO
WEDNESDAY...PARTICULARLY FOR SENSITIVE LOCATIONS.

A SMALL CRAFT ADVISORY MAY BE NEEDED OVER PORTIONS OF THE WATERS
TUESDAY INTO TUESDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY.

MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504-
WVZ050>053-055-501>506-031645-
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-
334 PM EDT SUN SEP 2 2012

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

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

HEAVY RAINFALL COULD LEAD TO LOCALIZED FLASH FLOODING MONDAY
THROUGH TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY.

JACKSON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
233 PM EDT SUN SEP 2 2012

MDZ017-018-021915-
ST. MARYS MD-CALVERT MD-
233 PM EDT SUN SEP 2 2012

...STRONG THUNDERSTORM TO AFFECT ST. MARYS AND CALVERT COUNTIES...

AT 231 PM EDT...A STRONG THUNDERSTORM WAS LOCATED IN CENTRAL SAINT
MARYS COUNTY...ABOUT 2 MILES NORTH OF GREAT MILLS...DRIFTING SLOWLY
EAST.

LOCATIONS IMPACTED INCLUDE LEXINGTON PARK...PATUXENT RIVER NAS AND
SAINT MARYS CITY.

THIS STORM IS PRODUCING FREQUENT CLOUD TO GROUND LIGHTNING. MOVE
INDOORS IMMEDIATELY FOR YOUR SAFETY. IF YOU CAN HEAR THUNDER...YOU
ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

HEAVY RAIN...UPWARDS OF ONE AND ONE HALF INCH TOTAL...WITH THIS
STORM WILL REDUCE VISIBILITIES TO BELOW ONE MILE AND MAY CAUSE
PONDING OF WATER ON ROADWAYS AND LOW LYING AREAS. AVOID DRIVING
THROUGH FLOODED ROADWAYS.

A FEW WIND GUSTS OF 25 TO 35 MPH CAN BE EXPECTED WITH THIS STORM.

&&

LAT...LON 3812 7635 3824 7658 3835 7653 3834 7640
      3832 7641 3832 7639 3830 7636 3828 7638
      3824 7638 3817 7634
TIME...MOT...LOC 1831Z 287DEG 4KT 3826 7649

SMZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
321 PM EDT SUN SEP 02 2012

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

0245 PM     FLASH FLOOD      LEXINGTON PARK          38.26N  76.45W
09/02/2012                   ST. MARYS          MD   911 CALL CENTER

            GREAT MILLS RD CLOSED DUE TO HIGH WATER IN LEXINGTON
            PARK.

&&

EVENT NUMBER LWX1201148

JACKSON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
650 PM EDT SUN SEP 02 2012

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

0640 PM     WATER SPOUT      4 NE EDGEMERE           39.26N  76.41W
09/02/2012                   BALTIMORE          MD   EMERGENCY MNGR

            WATERSPOUT OVER BACK RIVER REPORTED BY THE PUBLIC.

&&

EVENT NUMBER LWX1201149

SMZ

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
731 PM EDT SUN SEP 2 2012

WVZ505-506-030000-
EASTERN PENDLETON WV-WESTERN PENDLETON WV-
731 PM EDT SUN SEP 2 2012

...STRONG THUNDERSTORM TO AFFECT PENDLETON COUNTY...

AT 730 PM EDT...A STRONG THUNDERSTORM WAS LOCATED OVER UPPER TRACT...
MOVING EAST AT 10 MPH.

LOCATIONS IMPACTED INCLUDE DEER RUN.

HEAVY RAIN UPWARDS OF ONE INCH WITH THIS STORM WILL REDUCE
VISIBILITIES TO BELOW ONE MILE AND CAUSE PONDING OF WATER ON
ROADWAYS.

&&

LAT...LON 3882 7915 3869 7914 3875 7936 3885 7934
TIME...MOT...LOC 2330Z 283DEG 8KT 3879 7925

SMZ