National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 151333 AAA
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
933 AM EDT WED MAY 15 2013

.SYNOPSIS...
A FRONTAL BOUNDARY WILL APPROACH FROM PENNSYLVANIA LATE TODAY AND
STALL OUT OVER THE SOUTHERN MID-ATLANTIC THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
FORECAST FOR TODAY REMAINS A BIT TRICKY WITH ENHANCED CLOUD COVER
OVER THE FORECAST AREA THIS MORNING. WARM FRONT WILL CONTINUE TO
SLOWLY PUSH NORTHWARD THROUGH THE FORECAST AREA LATE MORNING.
ADDITIONALLY...NORTHWEST FLOW AND WEAK DISTURBANCE/VORT MAX
HELPING TO TOUCH OFF ISOLATED/SCATTERED LIGHT RAIN
SHOWERS/SPRINKLES WITH MORE ACTIVITY APPROACHING FROM PA. WILL
CONTINUE POPS MAINLY FROM NOVA NORTH TO THE MASON DIXON LINE.

THERE REMAINS QUITE A SPREAD IN MODEL GUIDANCE FOR HIGH
TEMPERATURES THIS AFTERNOON WITH THE WARMER MET AND COOLER MAV.
THOUGHT ABOUT LOWERING MAX TEMPS DUE TO CLOUD COVER BUT IAD AND
UPSTREAM SOUNDINGS INDICATE ELEVATED MIXED LAYER WITH 40-50 KT
850MB FLOW OUT OF THE WEST/NORTHWEST. ONCE MIXING DOES
OCCUR...TEMPERATURES SHOULD RESPOND FAIRLY QUICKLY AND WILL LEAVE
FORECAST MAX TEMPS IN THE UPPER 70S NORTHEAST TO LOW-MID 80S MOST
ELSEWHERE...POSSIBLY UPPER 80S OVER CENTRAL VA.

NAM AND GFS CONTINUE TO RUN TOO HIGH WITH SURFACE DEWPOINT
TEMPERATURES. 13Z ANALYSIS SHOWS DEWPOINTS IN THE 40S-LOWER
50S...SIMILAR OVER AREAS SOUTH OF THE CWFA. MODELS CONTINUE TO
WARM DEWPOINT TEMPERATURES INTO THE MIDDLE TO UPPER 60S WHICH
SEEMS TOO HIGH. CORRESPONDING CAPES ARE PROGGED TOO HIGH LEADING
TO QUESTIONS ABOUT HOW MUCH INSTABILITY WILL BE AVAILABLE FOR
CONVECTIVE DEVELOPMENT. STILL THINKING THAT CENTRAL AND SOUTHERN
PORTIONS OF THE FORECAST AREA WOULD BE CAPPED BUT NORTHERN
AREAS...ESPECIALLY NEAR THE MASON DIXON LINE HAVE THE BEST CHANCE
OF CONVECTION ALONG THE BOUNDARY ONCE CLOUD COVER MIXES OUT.
SEE NO REASON TO CHANGE HWO MENTION OF ISOLATED DAMAGING WIND
THREAT OVER NORTHERN AREAS.

WEAK COLD FRONT WILL PUSH THROUGH LATER TODAY/EARLY EVENING WITH
WIND SHIFT TO THE WEST EXPECTED. OVERNIGHT LOWS IN THE 60S FOR THE
MOST PART.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
FRONTAL BOUNDARY IS FORECAST TO SINK SOUTHWARD ACROSS THE SOUTHERN
MID-ATLANTIC THROUGH THE END OF THE WEEK...POSSIBLY SNAKING BACK UP
THE APPALACHIANS ON FRIDAY. WITH FRONTAL BOUNDARY OVER THE CWA ON
THURSDAY...WILL CONTINUE WITH CHANCE POPS MAINLY IN THE
AFTERNOON/EVENING WITH MAXIMA IN THE LOWER TO MID 80S.

WITH FRONT SAGGING A LITTLE FURTHER SOUTH INTO FRIDAY...WILL FOCUS
POPS ACROSS THE SOUTHERN HALF ON THE CWA WITH MAXIMA POSSIBLY A
COUPLE OF DEGREES LOWER.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
FRONTAL BOUNDARY IS FORECAST TO REMAIN SOUTH OF THE AREA OVER THE
WEEKEND...THEN LIFTS BACK NORTH AS A WARM FRONT EARLY NEXT WEEK IN
ADVANCE OF THE NEXT SHORTWAVE. FEW ADJUSTMENTS WERE MADE TO THE
FORECAST WHICH INCLUDE CHANCE POPS THROUGH MUCH OF THE PERIOD.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
MOSTLY MID DECKS EXPECTED INTO THIS AFTERNOON WITH SCATTERED
SPRINKLES OR RAIN SHOWERS POSSIBLE BUT MUCH OF THE RAIN NOT
EXPECTED TO REACH THE GROUND. SOUTHERLY WINDS OF 10-20KTS
EXPECTED. A FEW RAIN SHOWERS/ISOLATED STORMS POSSIBLE ESPECIALLY
NORTH TO THE MASON DIXON LINE THIS AFTERNOON WHICH COULD CAUSE
VSBY/CIGS TO BRIEFLY FALL BELOW VFR.

FRONTAL BOUNDARY IS FORECAST TO STALL OUT TO THE SOUTH OF THE AREA
DURING THE LATE WEEK-WEEKEND PERIOD. WITH BOUNDARY FAIRLY
CLOSE...CONVECTION IS POSSIBLE MAINLY IN THE AFTERNOON/EVENING EACH
DAY.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
THE AFTN HRS WILL SEE HIGHER SYNOPTIC GUSTS...W/ MOST AREAS IN
SOLID SCA RANGE AND A FEW GUSTS IN THE U20KT RANGE BEFORE SUNSET.
A FEW ISOLATED SHOWERS WILL ALSO CONTINUE THIS MRNG...AND AGAIN
ANOTHER ROUND OVER THE NRN BAY LATE TONIGHT.

FRONTAL BOUNDARY SLIPS SOUTH OF THE WATERS LATE WEEK AND REMAINS
SOUTH THROUGH THE WEEKEND. GRADIENT IS EXPECTED TO REMAIN FAIRLY
WEAK THROUGH THE PERIOD. AS WINDS BECOME SOUTHEAST OVER THE
WEEKEND...WINDS MAY CREEP UP CLOSE TO SCA LEVELS OVER PORTIONS OF
THE WATERS.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --
WATER LEVELS HAVE INCREASED WITH MORNING HIGH TIDE CYCLE YET
CRESTING BELOW FLOOD THRESHOLDS AT SENSITIVE AREAS. SOUTHERLY
CHANNELING WILL PERSIST MUCH OF TODAY THEN SHIFTING TO THE WEST
WITH A COLD FRONT LATER TODAY INTO TONIGHT. WATER LEVELS SHOULD
DECREASE FOR THE NEXT HIGH TIDE CYCLE.
-- End Changed Discussion --

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ531>534-
     537-539>541-543.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ530-
     535-536-538-542.
-- End Changed Discussion --

&&

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