Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 250114
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
914 PM EDT SUN MAY 24 2015

.SYNOPSIS...
HIGH PRESSURE LOCATED OVER THE WESTERN ATLANTIC WILL PROMOTE
WARMER AND MORE HUMID WEATHER OVER THE NEXT SEVERAL DAYS. AN
APPROACHING COLD FRONT WILL INCREASE THE RISK OF SHOWERS AND
THUNDERSTORMS STARTING TUESDAY AND CONTINUING LATER THIS WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
THE CENTER OF SFC HIGH PRESSURE IS LOCATED OFFSHORE EAST OF VA
THIS EVENING WITH A LIGHT SOUTHERLY FLOW IN PLACE. A DEEP UPPER
LEVEL TROUGH IS LOCATED OVER THE CENTRAL ROCKIES...WITH DOWNSTREAM
RIDGE AMPLIFICATION BEGINNING TO TAKE PLACE OVER THE EASTERN
CONUS. FOR TONIGHT...EXPECT ONLY SOME PATCHES OF MID AND HIGH
LEVEL CLOUDS SPILLING OVER THE RIDGE. DEW POINTS ARE NOW IN THE
50S IN MOST LOCATIONS...WHICH WILL SERVE TO LIMIT TEMPERATURE
FALLS. ANY ADDITIONAL FORECAST ADJUSTMENTS WILL LIKELY BE TO CLOUD
COVER AND TEMPERATURE...WHERE WE COULD SEE SOME OF THE TYPICAL
SHELTERED LOCATIONS DROP A LITTLE LOWER THAN THE CURRENT READINGS.
HOWEVER ON THE WHOLE...LOWS IN THE MID 50S TO LOWER 60S ARE
EXPECTED...WITH A FEW DEGREES MORE THAN THAT IN THE URBAN CENTERS.

OVER THE NEXT 24 HOURS...THE RIDGE ALOFT WILL SHIFT SLIGHTLY EAST
WHILE THE RIDGE AXIS WILL SHIFT EAST FASTER...ENDING UP OVER OUR
REGION BY LATE MONDAY AFTERNOON. THE HIGH PRESSURE WILL SHIFT A
BIT FURTHER EAST BUT ITS INFLUENCE WILL REMAIN AND THE
SOUTHWESTERLY FLOW OF MOIST AND WARM AIR ON ITS WESTERN PERIPHERY
WILL CONTINUE OVER OUR AREA. THIS WILL PROMOTE A CONTINUED TREND
OF WARMER AND MORE HUMID WEATHER...WITH TEMPERATURES RISING WELL
INTO THE 80S ON MONDAY. DEW POINTS WILL RISE INTO THE MID TO UPPER
50S.

SKIES ON MONDAY SHOULD BE MOSTLY SUNNY WITH HIGH CIRRUS AND A FEW
CUMULUS BEING THE MAIN FEATURES. THE RIDGE ALOFT SHOULD SUPPRESS
ANY CONVECTION AND KEEP THE WEATHER DRY DESPITE THE INCREASED
WARMTH AND HUMIDITY. WINDS WILL BECOME MORE NOTICEABLE AS THE
PRESSURE GRADIENT INCREASES...WITH GUSTS ABOVE 20 MPH LIKELY
ACROSS THE AREA MONDAY AFTERNOON.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
RETURN FLOW CONTINUES MONDAY NIGHT AS HIGH PRESSURE STAYS OFF THE
EAST COAST. THE UPPER LEVEL RIDGE WILL ALSO MOVE EASTWARD WHICH
WILL ALLOW MOISTURE TO INCREASE THROUGH THE COLUMN. SHOWERS ARE
POSSIBLE IN THE HIGHLANDS EARLY TUESDAY MORNING AS SOME
DISSIPATING CONVECTION MOVES INTO THE REGION. SCT SHOWERS AND
THUNDERSTORMS ARE EXPECTED TUESDAY AFTERNOON MAINLY ALONG AND WEST
OF THE BLUE RIDGE AS THE UPPER LEVEL RIDGE INFLUENCES AREAS CLOSER
TO THE EAST COAST. STORM MOTION IS EXPECTED TO BE S-SW ON THE WEST
SIDE OF THE RIDGE SO SHOWERS AND THUNDERSTORMS SHOULD STAY NEAR
AND WEST OF THE BLUE RIDGE. AS THE RIDGE MOVES EASTWARD TUESDAY
NIGHT...SOME SHOWERS WILL BE POSSIBLE ACROSS NRN MD. AT THIS
TIME...INSTABILITY AND SHEAR ARE WEAK AND ANY THUNDERSTORMS SHOULD
STAY SUB-SVR TUESDAY.

WEDNESDAY WILL BE WARMER AND MORE HUMID THAN TUESDAY AS THE UPPER
LEVEL RIDGE MOVES FURTHER OFF THE EAST COAST. THIS WILL LEAD TO
MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY WEDNESDAY
AFTERNOON. A DISTURBANCE IS ALSO EXPECTED TO APPROACH THE REGION
WEDNESDAY AS A UPPER LEVEL JET MOVES ACROSS THE EASTERN GREAT
LAKES. INSTABILITY AND SHEAR WILL INCREASE BY THE AFTERNOON AND
SOME STORMS WILL HAVE THE POTENTIAL TO BE SEVERE. HIGH PWATS WILL
ALSO LEAD TO HEAVY RAINFALL.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A COLD FRONT AT THE SURFACE WILL APPROACH THE REGION FROM THE
LOWER GREAT LAKES AND EASTERN OHIO VALLEY WEDNESDAY
NIGHT...ALLOWING FOR A COUPLE OF SHOWERS AND THUNDERSTORMS TO
LINGER IN PARTS OF THE REGION. LOW TEMPERATURES WILL BE ABOUT 10
TO 15 DEGREES ABOVE AVERAGE.

THE COLD FRONT SHOULD PUSH THROUGH THE REGION THURSDAY.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF AND
ALONG THE FRONT IN RESPONSE TO SOME DAYTIME HEATING. HIGH
TEMPERATURES WILL APPROACH 90 DEGREES IN MOST PLACES WITH MIDDLE
80S EXPECTED FARTHER TO THE WEST.

WE EXPECT THE COLD FRONT TO STALL ACROSS THE EASTERN HALF OF THE
REGION THURSDAY NIGHT AND FRIDAY...PROVIDING AMPLE OPPORTUNITY FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP AND PRODUCE HEAVY RAINFALL.
THERE WILL BE PLENTY OF MOISTURE ALONG THE FRONT AS WELL AS LIGHT
AND VARIABLE WINDS IN THE MIDDLE AND UPPER LEVELS OF THE
ATMOSPHERE...HENCE ANY ACTIVITY SHOULD BE MOVING SLOWLY FROM WEST
TO EAST. LOW TEMPERATURES THURSDAY NIGHT AND HIGH TEMPERATURES
FRIDAY COULD STILL BE 7 TO 10 DEGREES ABOVE AVERAGE.

THE COLD FRONT IS EXPECTED TO BRIEFLY RETURN NORTHWARD AS A WARM
FRONT FRIDAY NIGHT BEFORE A SECOND COLD FRONT...MODERATELY-
STRONG... APPROACHES THE REGION SATURDAY. WHILE SHOWER ACTIVITY
MAY BE SCATTERED FRIDAY NIGHT...SHOWERS AND THUNDERSTORMS WILL
DEVELOP SATURDAY ALONG THE COLD FRONT AND COULD BRING HEAVY
RAINFALL AND GUSTY WINDS. LOW TEMPERATURES FRIDAY NIGHT AND HIGH
TEMPERATURES SATURDAY COULD BE 10 DEGREES ABOVE NORMAL...REACHING
THE UPPER 60S AND NEAR 90...RESPECTIVELY.

THE COLD FRONT SHOULD SLOWLY PUSH THROUGH THE REGION SATURDAY
NIGHT INTO SUNDAY. SHOWERS AND THUNDERSTORMS WILL STILL LINGER
ALONG THE COLD FRONT SATURDAY NIGHT INTO SUNDAY...BUT BECOME MORE
ISOLATED IN THE POTOMAC HIGHLANDS LATER IN THE WEEKEND. LOWS
SATURDAY NIGHT AND HIGHS SUNDAY WILL STILL BE ABOVE AVERAGE.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH MONDAY NIGHT AS
OFFSHORE HIGH PRESSURE CONTROLS THE WEATHER. DESPITE INCREASED DEW
POINTS...THINK THE LOW LEVELS OF THE ATMOSPHERE ARE STILL TOO DRY
FOR ANY FOG FORMATION TONIGHT. ALSO A LIGHT SOUTHERLY WIND MAY
STAY IN PLACE. WINDS BETWEEN 180-230 DEG WILL INCREASE DURING THE
DAYLIGHT HOURS...WITH GUSTS UP TO 20-25 KT. THESE GUSTS WILL
SUBSIDE WITH SUNSET. CU SHOULD BE FEW AND FAR BETWEEN INVOF TAF
SITES MONDAY...WITH BASES OF 5-6 KFT IF THEY DO FORM.

BY TUESDAY AFTERNOON -SHRA/VCTS POSSIBLE MAINLY AT MRB/CHO.
-SHRA/TSRA ARE LIKELY AT ALL THE TERMINALS WEDNESDAY. SOME STORMS
MAY PRODUCE GUSTY WINDS AND HEAVY RAINFALL RESULTING IN SUB-VFR
CONDITIONS.

MVFR TO IFR CONDITIONS POSSIBLE AT ALL TERMINALS WEDNESDAY NIGHT
THROUGH THURSDAY WITH SHOWERS AND THUNDERSTORMS. WINDS GENERALLY
SOUTHWEST 5 TO 10 KNOTS WITH A FEW HIGHER GUSTS.

&&

.MARINE...
HIGH PRESSURE OFFSHORE EAST OF VA IS PROMOTING GENERALLY SOUTHERLY
WINDS OVER THE WATERS. GUSTS TO 20 KT HAVE BEEN CONFINED TO THE
SOUTHERN PORTION OF THE MD BAY...AND HAVE RELAXED IN THE PAST
HOUR. HAVE A SCA CONTINUING IN THIS AREA THROUGH THE NIGHT...BUT
IF THE TREND CONTINUES...MAY BE ABLE TO CANCEL AND SQUEEZE IN A
PERIOD OF NO HEADLINES THROUGH EARLY MORNING. HOWEVER THE
GRADIENT WILL STRENGTHEN MONDAY AND ALLOW S/SW WINDS TO COMMONLY
GUST TO 20-25 KT. A SCA NOW GOES INTO EFFECT FOR ALL WATERS AT 10
AM. THE SCA IS WHITTLED BACK TO PORTIONS OF THE BAY LATE MONDAY
NIGHT WHERE SOUTHERLY CHANNELING MAY CONTINUE. NO PRECIPITATION IS
EXPECTED THROUGH MONDAY NIGHT.

GUSTY S WINDS WILL CONTINUE ON THE WATERS TUESDAY AND WEDNESDAY
AND SCA MAY BE NEEDED OR EXTENDED. SHOWERS AND THUNDERSTORMS
POSSIBLE WEDNESDAY AND SOME MAY PRODUCE GUSTY WINDS AND LOW VSBYS
ON THE WATERS.

SMALL CRAFT ADVISORY CONDITIONS POSSIBLE WEDNESDAY NIGHT THROUGH
THURSDAY...PRIMARILY FOR THE MAIN STEM CHESAPEAKE BAY.

&&

.CLIMATE...
UNUSUALLY HOT TEMPERATURES FOR THIS EARLY IN THE YEAR ARE FORECAST
DURING MUCH OF THE UPCOMING WEEK. BELOW IS A LIST OF RECORD DAILY
WARM TEMPERATURES FOR THE UPCOMING WEEK.

.......RECORD WARM TEMPERATURES FOR DCA........
DATE...RECORD HIGH...........RECORD HIGH MIN...
5/25...94 (1880).............71 (2012).........
5/26...96 (1880).............74 (1991).........
5/27...95 (1965/1914/1880)...75 (1991).........
5/28...97 (1941).............75 (1991).........
5/29...97 (1991/1969)........74 (1991).........
5/30...98 (1991).............74 (1991).........

.......RECORD WARM TEMPERATURES FOR BWI........
DATE...RECORD HIGH...........RECORD HIGH MIN...
5/25...94 (1991).............70 (1936).........
5/26...94 (1914).............74 (1880).........
5/27...95 (1965/1941)........75 (1880).........
5/28...97 (1941).............78 (1941).........
5/29...97 (1969).............71 (1908).........
5/30...98* (2011/1991).......72 (1895).........
*ALSO HIGHEST OBSERVED MAY MONTHLY TEMPERATURE

.......RECORD WARM TEMPERATURES FOR IAD........
DATE...RECORD HIGH...........RECORD HIGH MIN...
5/25...92 (1991).............67 (2004).........
5/26...92 (2007).............70 (1991).........
5/27...92 (2010/1965)........69 (2008/1991)....
5/28...90 (2012/1991)........70 (1991).........
5/29...97* (1969)............69 (2012).........
5/30...95 (2006/1991/1987)...70 (2011).........
*ALSO HIGHEST OBSERVED MAY MONTHLY TEMPERATURE

BELOW IS THE LONGEST STRETCH OF CONSECUTIVE DAYS AT OR ABOVE 90 F
DURING THE MONTH OF MAY.

DCA...7 DAYS (05/25-05/31/1991)
BWI...7 DAYS (05/25-05/31/1991)
IAD...7 DAYS (05/25-05/31/1991)

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 6 AM EDT TUESDAY FOR
     ANZ531-538>540-542.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ532>534-541-
     543.
     SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 2 AM EDT TUESDAY FOR
     ANZ530-535-536.
     SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR ANZ537.

&&

$$
SYNOPSIS...RCM
NEAR TERM...ADS/RCM
SHORT TERM...HAS
LONG TERM...KLW
AVIATION...ADS/HAS/KLW
MARINE...ADS/HAS/KLW
CLIMATE...DFH



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