Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 291332
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
932 AM EDT FRI AUG 29 2014

.SYNOPSIS...
HIGH PRESSURE BUILDS OVER THE NORTHERN MID-ATLANTIC TODAY...THEN
MOVES OFFSHORE FOR THE WEEKEND. A WARM FRONT WILL LIFT NORTH
THROUGH THE AREA LATE SATURDAY. A COLD FRONT WILL APPROACH DURING
THE FIRST PART OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
SFC HIPRES NY/PA...RDGG INTO MD/VA THIS MRNG. IN ADDITION...RDGG
BLDG ALOFT /H8-5/. AS A RESULT...IT/LL BE AWFULLY DFCLT TO DVLP
CLDS TDA. 12Z RAOB HINTS AT PERHAPS A FEW FLAT CU INVOF H8...AND
CANT RULE OUT A STREAMER OR TWO OF CI.

SNDG BASED RAOB MAXT A PINCH LWR THAN FCST. W/ NEARLY FULL
INSOLATION...AM NOT GOING AGAINST ERLR REASONING ON SIDING WARM.
GRIDS ONLY A DEGF OR TWO ABV LAMP. WL ADJUST IF NCSRY.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SATURDAY/...
AS HIGH PRESSURE MOVES OFF THE COAST TONIGHT INTO SATURDAY....WINDS
TURN TO THE SOUTHEAST. RETURN FLOW WILL BOLSTER AN INCREASE IN
DEWPOINTS/MOISTURE DURING THIS TIME...RESULTING IN INCREASING CLOUDS
OVERNIGHT AND PARTLY TO MOSTLY CLOUDY SKIES FOR SATURDAY.

FOLLOWED SREFS FOR POPS...KEEPING CWA GENERALLY DRY TONIGHT THEN
BRINGING CHANCE POPS INTO THE NORTHERN VIRGINIA PIEDMONT AND AREAS
ALONG/WEST OF THE BLUE RIDGE. THIS IS IN DECENT AGREEMENT WITH 00Z
GFS/ECMWF.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE CALENDAR WILL READ SEPTEMBER...BUT THE CONDITIONS WILL RESEMBLE
WHAT WE WOULD TYPICALLY GET BACK IN JULY/AUG. CAUGHT UNDERNEATH A
STRENGTHENING UPPER RIDGE...THE PLUME OF MOISTURE AND WARMER AIR
FROM THE SOUTH WILL BE ON THE CONVEYOR BELT INTO EARLY NEXT WEEK.
AFTER A COUPLE OF DAYS GRADUALLY BUILDING TO CLOSE OUT THE CURRENT
WEEK...THE HEATING WILL REACH ITS CLIMAX OVER THE ERN SEABOARD ON
SUN...AS THE TROUGH RESPONSIBLE FOR THIS BUILD-UP FINALLY PASSES BY
THE AREA. THE RELATIVELY MINOR AND LOW AMPLITUDE TROUGH AXIS WILL
ACTUALLY BE A SERIES OF OFFSET KINKS IN THE UPPER FLOW THAT CONNECT
FROM HUDSON BAY TO THE GULF COAST. THE COMBINATION OF THESE FEATURES
CENTERED A COUPLE OF STATES TO OUR WEST WILL FORCE THE ATLC COAST
RIDGE TO AMPLIFY AND CREATE A MORE PRONOUNCED FETCH OF WARM/HUMID
AIR FROM THE SRN ATLC STATES.

THE SRN HALF OF THE UPPER RIDGE WILL BE STRONG ENOUGH TO DEFLECT THE
INCOMING SHORTWAVE UP/OVER THE NRN SIDE - FROM ABOUT THE CAROLINAS
AND NWD. A MUCH MORE POTENT TROUGH DIVING DOWN INTO THE NRN PLAINS
WILL ALSO FORCE THE TROUGH QUICKLY OVER AND N OF OUR AREA SUN INTO
MON. INSTABILITY LOOKS TO BE MARGINAL BUT HEATING SHOULD BE
SUFFICIENT FOR SCT`D TSTMS DURING THE LATTER HALF OF THE DAY. SHEAR
PROFILE NOT OVERLY FAVORABLE W/ A LARGELY WLY UNIDIRECTIONAL FLOW IN
THE CRITICAL BOUNDARY LAYER...SO THE STRONGEST ACTIVITY WOULD LIKELY
BE MORE LOCALIZED WHERE THE BEST PARAMETERS/FORCING COME TOGETHER -
POSSIBLY OUTFLOW DRIVEN AS WELL.

ELEVATED HEAT INDICES WILL ALSO BE A CONCERN HEADING INTO EARLY NEXT
WEEK ESPECIALLY. DEWPOINTS WILL AGAIN BE HOVERING IN THE L70S -
WHICH CAN ADD A HIGH LEVEL OF DISCOMFORT TO ANY AMBIENT TEMP. AND W/
TEMPS EXPECTED TO CRACK THE 90 DEG MARK...HEAT INDICES WILL EASILY
REACH THE MID...IF NOT U90S - BOTH SUN AND MON AFTN. SKIES WILL
WAVER BETWEEN PARTLY SUNNY AND MOSTLY CLOUDY WHICH MAY HELP A LITTLE
IN TERMS OF MAX POTENTIAL HEATING BUT IT WILL STILL BE PLENTY
HOT/HUMID FOR THIS TIME OF YEAR.

THE UPPER RIDGE BEING DISPLACED ONLY SLIGHTLY TO THE SOUTH AS THE
TROUGH SLIDES BY WILL REBOUND BACK OVER THE MID-ATLC THRU THE REST
OF THE WEEK. LONG RANGE MODELS CONSISTENTLY SHOWING US ON THE NRN
FRINGE OF THE HOTTER CONDITIONS THRU MUCH OF THE WEEK...W/ A
COOLER/MORE ACTIVITY WX RESIDING JUST N OF THE MASON-DIXON LINE W/
ONE TROUGH AFTER ANOTHER SLIDING BY JUST TO OUR NORTH. BRIEF PERIODS
OF CONVECTIVE ACTIVITY MAY DOT THE AREA BY MID WEEK AS A COLD FRONT
STRADDLES THE REGION BUT NOT MUCH IN THE WAY OF AN ORGANIZED OR
AIRMASS MODIFYING SYSTEM EXPECTED THRU THE CURRENT FORECAST PERIOD.

&&

.AVIATION /13Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL BE IN CONTROL TODAY WITH FEW-SCT CU/CI THIS
AFTERNOON/EVENING. POTENTIAL EXISTS FOR LOW CLOUDS TO DEVELOP LATE
TONIGHT OR SATURDAY MORNING AS FLOW BECOMES SOUTHEAST. CONFIDENCE IS
LOW HOWEVER. PER SREFS...CHO MAY HAVE THE GREATEST CHANCE BUT EVEN
THAT IS UNCERTAIN. LTST TAFS HV MVFR AT CHO...OTHERWISE VFR.

AN UPPER RIDGE WILL CONTINUE TO BUILD-IN HEAT/HUMIDITY SUN INTO
MON...W/ A POSSIBLE WAVE OF SCATTERED SHOWERS/TSTMS POSSIBLE SUN
AFTN/EVE. ANOTHER LESSER POTENTIAL EXISTS ON MON AS WELL...AS THE
HOT/HUMID AIRMASS STAYS IN PLACE FOR THE NEXT SEVERAL DAYS. ONLY
BRIEF AND SHORT-LIVED PERIODS OF PRECIP POSSIBLE INTO MID NEXT
WEEK...BUT MAINLY DRY AND MOSTLY SUNNY EACH DAY.

&&

.MARINE...
NE FLOW GNLY AOB 10 KT /TPLM2 10-15 KT/ ATTM. AS HIPRES BLDS...
WNDS SHUDNT GO MUCH HIER. IF ANYTHING...XPCT A LTL BIT OF A DECR
THRU THE AFTN.

HIGH PRESSURE MOVES OFF THE COAST TONIGHT AND SATURDAY...RESULTING
IN WINDS VEERING TO THE SE. SPEEDS EXPECTED TO REMAIN BELOW SCA
ATTM.

S-SWLY WINDS WILL BE IN PLACE FOR THE FIRST HALF OF THE COMING
WEEK...AS A HIGH SITS JUST OFF THE ATLC COAST AND STEERS WARM/HUMID
AIR UP ACROSS THE ERN SEABOARD. ONLY MINOR PERIODS OF SLY CHANNELING
AND/OR SCA CONDITIONS POSSIBLE INTO THE MIDDLE OF NEXT WEEK. A WEAK
FRONT WILL LIKELY CROSS THE WATERS ON SUN...W/ ANOTHER PASSAGE
POSSIBLE FROM A DIFFERENT SYSTEM TO OUR NORTH ON WED.

&&

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

&&

$$
SYNOPSIS...BPP/GMS
NEAR TERM...HTS
SHORT TERM...BPP
LONG TERM...GMS
AVIATION...BPP/GMS
MARINE...HTS/BPP/GMS






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