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000
FXUS61 KLWX 200731
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
331 AM EDT MON MAY 20 2013

.SYNOPSIS...
A WARM FRONT WILL PASS THROUGH THE AREA TODAY WHILE AN UPPER-LEVEL
DISTURBANCE MOVES THROUGH THE AREA. HIGH PRESSURE OVER THE ATLANTIC
WILL PROVIDE A SOUTHERLY FLOW FOR TUESDAY THROUGH
THURSDAY...BRINGING WARM AND HUMID CONDITIONS. A COLD FRONT WILL
PASS THROUGH THE AREA LATE IN THE WEEK AND COOLER CONDITIONS WILL
RETURN FOR NEXT WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
CURRENT ANALYSIS SHOWS A STATIONARY BOUNDARY OVER THE REGION EARLY
THIS MORNING WHILE UPPER-LEVEL LOW PRESSURE SLOWLY MOVES INTO THE
AREA FROM WEST VIRGINIA.

THE STATIONARY BOUNDARY SEPARATES WARM AND MOIST AIR TO THE SOUTH
AND WEST FROM COOLER MARINE AIR TO THE NORTH AND EAST. WIDESPREAD
LOW CLOUDS ALONG WITH FOG/DRIZZLE ARE EXPECTED TO THE NORTH AND
EAST OF THE BOUNDARY ACROSS NORTHEASTERN MARYLAND. HOWEVER...PLENTY
OF MOISTURE IS TRAPPED UNDERNEATH THE NOCTURNAL INVERSION SO AREAS
OF LOW CLOUDS AND FOG/DRIZZLE ARE ALSO EXPECTED SOUTH AND WEST OF
THE BOUNDARY. A FEW SHOWERS ARE POSSIBLE EARLY THIS
MORNING...ESPECIALLY CLOSER TO THE UPPER-LEVEL LOW ACROSS CENTRAL
VIRGINIA.

THE STATIONARY BOUNDARY WILL MOVE NORTH AS A WARM FRONT LATER THIS
MORNING AND AFTERNOON. SOUTHERLY WINDS BEHIND THE BOUNDARY WILL
USHER IN WARM AND HUMID CONDITIONS. THE UPPER-LEVEL LOW WILL SLOWLY
MOVE INTO THE REGION DURING THIS TIME. THE COMBINATION OF WARM AND
HUMID CONDITIONS ALONG WITH COOLER AIR ALOFT WILL CAUSE AN UNSTABLE
ATMOSPHERE THIS AFTERNOON. SHOWERS AND T-STORMS ARE EXPECTED TO
DEVELOP DURING THIS TIME. A LIGHT WIND FIELD AND INSTABILITY
REMAINING SOMEWHAT LIMITED DUE TO CLOUD COVER SHOULD KEEP THE SEVERE
THREAT LOW. SCATTERED SHOWERS/T-STORMS MAY CONTINUE INTO THIS
EVENING...BUT DRY CONDITIONS ARE EXPECTED OVERNIGHT DUE TO THE LOSS
OF DAYTIME HEATING.

WARM AND HUMID CONDITIONS WILL PERSIST OVERNIGHT WITH MIN TEMPS
HOLDING IN THE 60S FOR MOST AREAS. PLENTY OF MOISTURE UNDERNEATH THE
NOCTURNAL INVERSION WILL RESULT IN AREAS OF LOW CLOUDS/FOG.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
MID-ATLANTIC WILL RESIDE IN A WARM SECTOR DURING THE MID-WEEK. THIS
WILL ALLOW FOR A WARM UP TUESDAY THROUGH WEDNESDAY...WITH MAXIMA IN
THE MID 80S. IF THERE IS MORE SUNSHINE...THEN MAXIMA COULD EVEN
REACH UPPER 80S IN SOME LOCATIONS.

TUESDAY MORNING MAY START OFF WITH SOME FOG/STRATUS...BUT CLOUDS
SHOULD BREAK FOR SOME SUNSHINE DURING THE AFTERNOON. MODELS SHOW
MOISTURE IN PLACE...AND SOME INSTABILITY AS WELL HOWEVER AM HAVING
TROUBLE FINDING ANY GOOD FORCING/FOCUSING MECHANISMS FOR CONVECTION
THEREFORE CONTINUE TO FAVOR A DRY FORECAST FOR TUESDAY WITH ONLY
ISOLATED CONVECTION ACROSS THE NORTHWEST.

AIR MASS REMAINS THE SAME ON WEDNESDAY. MODELS HINT AT A BETTER
CHANCE OF DIURNAL CONVECTION SO HAVE INCLUDED CHANCE POPS IN THE
FORECAST FOR SCATTERED THUNDERSTORMS ACROSS THE CWA.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SLIGHT HEIGHT FALLS ARE FORECAST TOWARD THE END OF THE WEEK AS AN
UPPER TROUGH APPROACHES...IN TANDEM WITH A COLD FRONT. THERE IS SOME
QUESTION REGARDING TIMING OF THE FROPA...LATEST GUIDANCE SUGGESTING
LATE THURSDAY INTO EARLY FRIDAY. DUE TO UNCERTAINTY HAVE CHANCE POPS
IN THE THURSDAY THROUGH FRIDAY TIME FRAME...AND WE CAN FINE TUNE THE
TIMING AS WE GET CLOSER.

THERE IS GOOD AGREEMENT THAT THE FRONT WILL HAVE MOVED THROUGH THE
AREA BY THE WEEKEND...FAVORING A COOLER/DRIER AIR MASS. FORECAST
REFLECTS MOSTLY CLEAR SKIES AND TEMPERATURES NEAR CLIMATOLOGY.

&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
PLENTY OF MOISTURE REMAINS TRAPPED UNDERNEATH THE NOCTURNAL
INVERSION. LOW CLOUDS AND AREAS OF FOG WILL CAUSE IFR/SUB IFR
CIGS/VSBYS EARLY THIS MORNING. A WARM FRONT WILL PASS THROUGH THE
TERMINALS LATER THIS MORNING AND CONDITIONS WILL IMPROVE BY LATE
MORNING/EARLY AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS ARE
EXPECTED...MAINLY THIS AFTERNOON AND EVENING. AREAS OF LOW
CLOUDS/FOG ARE POSSIBLE AGAIN TONIGHT.

THERE IS THE POTENTIAL FOR SOME FOG/STRATUS EARLY
TUESDAY...PARTICULARLY IF SOME OVERNIGHT CLEARING TAKES PLACE AS
LOW LEVEL MOISTURE REMAINS. BUT CONFIDENCE REMAINS ONLY LOW-MODERATE
ON OCCURRENCE ATTM. VFR EXPECTED TO PREVAIL THE BALANCE OF TUESDAY.
CHANCE OF THUNDERSTORMS RETURNS FOR WEDNESDAY AFTERNOON...AND
SHRA/TSRA REMAIN POSSIBLE UNTIL A COLD FRONT MOVES THROUGH LATE
THURSDAY INTO EARLY FRIDAY.

&&

.MARINE...
A STATIONARY BOUNDARY OVER THE WATERS WILL MOVE TO THE NORTH AS A
WARM FRONT TODAY. SOUTHERLY WINDS ARE EXPECTED TODAY THROUGH TONIGHT
BEHIND THIS BOUNDARY. HOWEVER...WIND SPEEDS WILL REMAIN BELOW SCA
CRITERIA. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED...MAINLY
THIS AFTERNOON AND EVENING.

SOUTHERLY WINDS ARE EXPECTED DURING THE MID WEEK UNTIL A COLD FRONT
MOVES THROUGH TOWARD THE END OF THE WEEK SWITCHING WINDS TO THE
NORTHWEST. SOUTHERLY FLOW CHANNELLING UP THE BAY COULD BRING
MARGINAL SCA CONDITIONS UP THE BAY PARTICULARLY DURING THE LATE
AFTERNOON/EVENINGS.

&&

.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES REMAIN NEAR NORMAL EARLY THIS MORNING. SOUTHERLY
WINDS ARE WILL DEVELOP OVER THE WATERS TODAY AND ANOMALIES ARE
EXPECTED TO INCREASE. HOWEVER...THE HIGH TIDE THIS AFTERNOON WILL BE
THE LOWER OF THE TWO. WILL HAVE TO WATCH SOUTHERLY FLOW DURING THE
MID-WEEK AS IT MAY SUPPORT AN INCREASE IN DEPARTURES AGAIN. BUT
CBOFS KEEPS WATER LEVELS BELOW MINOR THRESHOLDS THROUGH HIGH TIDES
TUESDAY AFTERNOON.

&&

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

&&

$$
SYNOPSIS...BJL/BPP
NEAR TERM...BJL
SHORT TERM...BPP
LONG TERM...BPP
AVIATION...BJL/BPP
MARINE...BJL/BPP
TIDES/COASTAL FLOODING...BJL/BPP