Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 240625
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
225 AM EDT THU APR 24 2014

.SYNOPSIS...
COOL CANADIAN HIGH PRESSURE SLOWLY BUILDS IN FROM THE NORTHWEST
OVERNIGHT. HIGH PRESSURE THEN SLIDES OVER THE REGION INTO THURSDAY
MORNING...LOCATING OFF THE SOUTHEAST COAST THURSDAY AFTERNOON. A
SERIES OF WEAK FRONTS WILL CROSS THE AREA FRIDAY INTO THE WEEKEND.
A PERIOD OF UNSETTLED WEATHER IS EXPECTED OVER THE AREA EARLY NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPPER TROUGH AXIS HAS SHIFTED OFFSHORE PER LATEST WATER VAPOR
IMAGERY...AS SFC HIGH PRESSURE BUILDS SWD FROM THE GREAT LAKES
REGION. THE RESULT WILL BE CLEAR SKIES OVERNIGHT AND DECREASING NW
WINDS. WITH THE HIGH PRESSURE TO THE WEST OF THE AREA...ANOTHER
ROUND OF CAA OVERNIGHT WILL PUSH TEMPS INTO THE MID-UPPER 30S
INLAND AND INTO THE LOW 40S NEAR THE COAST. WINDS WILL NOT
COMPLETELY DE-COUPLE TONIGHT...RANGING FROM 5-10 MPH INLAND TO 10
TO 15 NEAR THE COAST. COMBINE LIGHT MIXING WITH RATHER DRY GROUND
CONDITIONS AND LOW DEWPOINTS...DO NOT ANTICIPATE WIDESPREAD FROST
AND WILL LEAVE OUT OF GRIDS. HOWEVER...PATCHY FROST IS POSSIBLE IN
SHELTERED LOCALES.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/...
SFC HIGH PRESSURE CENTERS OFF THE SE COAST THURS AS AN UPPER
RIDGE BUILDS OVER THE ERN CONUS. UPPER TROUGH OVER THE
INTERMOUNTAIN WEST WILL DE-AMPLIFY AND EJECT NEWD INTO THE PLAINS
THURS...PUSHING AN ASSOCIATED COLD FRONT INTO THE MS VALLEY. FLOW
RETURNS TO THE SOUTH LATE THURS-THURS NIGHT AS A WARM FRONT LIFTS
OVER THE REGION. MID-LEVEL WLY FLOW OVER THE GULF STATES INTO THE
MID-ATLANTIC WILL PREVENT MUCH OF A MOISTURE RETURN INTO THE
REGION....SO DRY CONDITIONS WILL PREVAIL. NWLY WINDS WILL NOT BE
AS STRONG THURS AFTERNOON...BUT MIN RH VALUES IN THE UPPER TEENS-
LOW 20S AND DRY FUELS WILL AGAIN RESULT IN POTENTIAL FIRE WX
CONCERNS. PLEASE REFER TO FIRE WEATHER SECTION BELOW FOR MORE
INFORMATION.

RIDGE AXIS PUSHES OFFSHORE FRI MORNING AS THE UPPER WAVE REACHES
THE OH VALLEY. QUESTIONS STILL EXIST ON STRENGTH OF THE UPPER WAVE
AS IT CROSSES THE MID-ATLANTIC REGION FRI AFTERNOON...WITH THE
LATEST GFS TRENDING SHARPER THAN ITS PREVIOUS RUNS AND COMING
MORE IN LINE WITH ITS NAM/ECMWF COUNTERPARTS. COLD FRONT WILL PUSH
ACROSS THE REGION FRI AFTERNOON-EVENING. SHORT LIVED LOW-LEVEL SW
FLOW WILL BE ABLE TO ADVECT MODEST PRECIP WATER VALUES OF 1-1.25
INCHES INTO THE REGION...BUT DEWPOINTS ONLY PROGGED TO WARM INTO
THE UPPER 40S TO NEAR 50 FRI. WITH THE LOCAL AREA IN THE WARM
SECTOR FRI...TEMPS WILL WARM INTO THE UPPER 70S TO NEAR 80
(DEPENDING ON FRONTAL TIMING). COMBINATION OF WARM TEMPS AND
THETA-E ADVECTION WILL RESULT IN A MARGINALLY UNSTABLE AIRMASS
(MLCAPE <500 J/KG)...MOSTLY OVER ERN VA/NERN NC. ALSO...LITTLE
INSTABILITY/LIFT PROGGED IN THE MIXED PHASE LAYER SO ANTICIPATE
ONLY ISOLATED/SLIGHT CHANCE THUNDER IN CONVECTION. JUST LIKE
YESTERDAYS FRONT...BIGGEST LIMITATIONS ARE WSW FLOW AND LOW
DEWPOINTS. SHEAR IS ALSO MARGINAL (~30-35 KT) SO DO NOT ANTICIPATE
ORGANIZED CONVECTION ALONG THE WEAKLY FORCED FRONT. WITH THAT
SAID...WILL MAINTAIN CHANCE POPS OVER THE REGION FRI AFTERNOON
ALONG/BEHIND THE FRONT. QPF AMOUNTS WILL GENERALLY BE LESS THAN
ONE TO TWO TENTHS.

FRONT PUSHES OFFSHORE FRI NIGHT AS A SECONDARY DRY COLD FRONT
ASSOCIATED WITH AN UPPER LOW OVER THE GREAT LAKES APPROACHES FROM
THE NW. BREEZY WLY/DOWNSLOPE FLOW SAT AND INCREASING LOW LEVEL
THICKNESS VALUES WILL RESULT IN DAYTIME TEMPS AROUND 80 DEGS MOST
LOCALES...EVEN BEHIND FRIDAYS FRONT. NARROW BAND OF MOISTURE AND
MEASURABLE PRECIP FORECAST TO REMAIN NORTH OF THE LOCAL AREA LATE
SAT-SAT EVENING.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
MODELS CONTINUE TO POINT TO A HIGHLY AMPLIFIED/BLOCKY PATTERN OVER
THE CONUS NEXT WEEK...RESULTING IN AN INCREASINGLY WET PERIOD.

MODELS CONTINUE TO STRUGGLE WITH THIS BLOCKY FLOW...MAINLY IN
LOCATION OF FRONTAL BOUNDARY PROGGED TO BE DRAPPED ACROSS THE RGN
ALONG WITH TIMING OF SEVERAL BATCHES OF MSTR PROGGED TO ROTATE NE
FROM THE DEEP SOUTH. WHAT TODAYS MODELS SHOW DIFFERENT FROM YSTRDYS
IS A SLOWER START TO THE PCPN MON...SOMEWHAT HIGHER CONFIDENCE FOR
AN EXTNDD PRD OF WETNESS FROM MON NITE THRU WED ALONG WITH A FRONTAL
BOUNDARY THAT WILL LIKELY PLAY HAVOC WITH TEMPS.

KEPT SUN DRY / SEASONABLE AS H5 RIDGE BUILDS ACROSS THE AREA. WARM
FRONT APPRCHS THE RGN FROM THE SW SUN NIGHT...BUT GUID SUGGESTS ANY
MOISTURE STAYS W OF FA THRU 12Z MON. LOWS SAT / SUN NIGHTS IN THE
M40S-L50S. HIGHS SUN 70-75 WEST OF THE BAY...M-U60S ALONG THE COAST.

FORECAST RATHER PROBLEMATIC NEXT WEEK AS THE MODELS DIFFER ON WHERE
THIS FRONTAL BNDRY SETS UP. THIS WILL LIKELY DETERMINE TMPS AND PCPN
TYPES (CONVECTIVE VS STRATIFORMED RAIN). UPR LVL LOW PROGGED TO
SLOWLY EJECT EAST FROM THE NATIONS MID SECTION MON NIGHT ONLY TO THE
OHIO VLLY BY WED. A MOIST E-SE FLOW WILL LIKELY ADD TO THE MOISTURE
CONTENT RESULTING IN PERIODIC CHCS FOR PCPN THRU THE PRD. FRNTL
BNDRY MAY ALSO TRY TO MAKE A RUN FARTHER NORTH BY WED AS SFC LOW
BEGINS TO CROSS THE MTS. TRAILING COLD FRONT WILL EVENTUALLY PUSH
ALL THIS OUT TO SEA...BUT THAT MIGHT NOT BE UNTIL THURSDAY. UPSHOT
WILL CARRY HIGH CHC POPS (SHWRS) MON THROUGH WED. TMPS COOLEST
(L-M60S) ALONG THE COAST DUE TO AN ONSHORE FLOW. HIGHS U60S-L70S
WEST OF THE BAY. LOWS IN THE 50S.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
HI PRES CONTG TO BUILD OVR THE RGN THROUGH TDA...RESULTING IN
DCRSG NNW WNDS. A LTL BIT GUSTY TO BETWEEN 15 TO 20 KT INTO THIS
MRNG...ESP NR THE CST. WNDS DIMINISH OVR INLAND LOCATIONS TO
AROUND 5 KT BY LT TDA. VFR TDA THROUGH TNGT.

AN AREA OF LOW PRESSURE AND AN ASSOCIATED COLD FRONT WILL BRING
SCATTERED SHOWERS AND A FEW THUNDERSTORMS FRIDAY. BRIEF PERIODS OF
IFR WILL BE PSBL AT THE TAF SITES. HIGH PRESSURE BUILDS INTO THE
REGION DURING THE WEEKEND WITH VFR AND DRY WEATHER TAKING OVER
THROUGH MONDAY. THE NEXT WEATHER SYSTEM BRINGS A GOOD CHANCE FOR
PCPN BY TUESDAY.

&&

.MARINE...
HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE MID ATLANTIC STATES
OVERNIGHT...KEEPING NW WINDS JUST ABOVE THE SCA THRESHOLD. WINDS IN
THE RIVERS AND SOUND ARE FORECAST TO BE NO HIGHER THAN 15 KNOTS...
EXCEPT IN THE LOWER JAMES RIVER WHERE SCA ENDS AT MIDNIGHT.

WINDS BEGIN TO DIMINISH BY THURSDAY MORNING. SCA DROPS OFF LATE
THURSDAY MORNING IN THE BAY AND IN THE COASTAL WATERS BY 4 PM
THURSDAY.

SOUTHERLY WINDS INCREASE AHEAD OF A COLD FRONT ON FRIDAY. THESE
SHOULD STAY BELOW SCA. BEHIND THE FRONT...CURRENT INDICATIONS HAVE THE
PRESSURE GRADIENT TOO WEAK FOR SCA CONDITIONS DURING THE WEEKEND.

&&

.FIRE WEATHER...
DRY CONDITIONS (MIN RH VALUES 15-25%) WILL OCCUR AGAIN ON
THURSDAY. HOWEVER...WINDS WILL BE LIGHTER THAN TODAY. THIS WILL
PRECLUDE THE NEED FOR ANY RED FLAG WARNINGS OVER THE LOCAL AREA.
NW WINDS DO INCREASE TO AROUND 15 MPH WITH GUSTS 20-25 MPH DURING
THE LATE MORNING/EARLY AFTN HOURS ON THE LOWER MD EASTERN SHORE.
GIVEN HOW LOW RH VALUES WILL BE THURS AFTN COUPLED WITH LOW FUEL
MOISTURE CONDITIONS...HAVE OPTED FOR AN INCREASED FIRE DANGER
STATEMENT FOR OUR MD COUNTIES...AFTER COORDINATION WITH MD FIRE
OFFICIALS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...INCREASED FIRE DANGER FROM 11 AM EDT THIS MORNING THROUGH THIS
     AFTERNOON FOR MDZ021>025.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
     ANZ630>632-634.
     SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR ANZ650-
     652-654-656-658.

&&

$$
SYNOPSIS...SAM
NEAR TERM...JDM/SAM
SHORT TERM...SAM
LONG TERM...MPR
AVIATION...ALB/LSA
MARINE...MPR/LSA
FIRE WEATHER...AKQ





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