Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 060842
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
442 AM EDT WED MAY 6 2015

.SYNOPSIS...
A WEAK COLD FRONT ACROSS PENNSYLVANIA WILL DRIFT SOUTHWARD ACROSS
THE AREA TODAY BEFORE DISSIPATING TONIGHT. HIGH PRESSURE BUILD
OVER THE NORTHERN MID- ATLANTIC THURSDAY. LOW PRESSURE OFF THE
CAROLINA COAST FRIDAY WILL GRADUALLY ERODE THIS WEEKEND...SENDING
ITS MOISTURE NORTHEASTWARD. A COLD FRONT WILL ARRIVE EARLY NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO INCLUDE SOUTHERN FAUQUIER AND STAFFORD COUNTIES IN THE
DENSE FOG ADVISORY...LASTING UNTIL 8 AM.

DENSE FOG ADVISORY CONTINUES FOR PORTIONS OF THE SHENANDOAH
VALLEY EARLY THIS MORNING. CLEARING SKIES AND LIGHT/VRB WINDS HAVE
LED TO FOG DEVELOPMENT WITH MANY REPORTS OF 1/4 MILE OR LESS. THE
ADVISORY IS IN EFFECT UNTIL 12Z...WITH VIS EXPECTED TO IMPROVE
THEN AS THE FOG DISSIPATES WITH HEATING. PATCHES OF FOG PSBL
ACROSS THE REMAINDER OF THE PIEDMONT NORTH INTO CENTRAL MD.

COLD FRONT CURRENTLY POSITIONED JUST NORTH OF THE MASON-DIXON WILL
NUDGE SOUTH TODAY...EVENTUALLY STALLING OVER NORTHERN PORTIONS OF
THE CWA. THIS FRONTAL BOUNDARY WILL YET AGAIN PROVIDE THE BASIS FOR
SHOWER AND TSTM DEVELOPMENT TODAY WITH LACK OF FORCING ALOFT AS
RIDGING BUILDS IN. VORT MAX PUSHING THRU PA EARLY THIS MORNING HAS
TRIGGERED SHOWERS...WITH ISO SHOWERS NOTED AS FAR SOUTH AS SOUTHERN
PA. ISO SHOWERS COULD CROSS THE STATE LINE INTO NORTHERN MD THRU
12Z...BUT OVERALL MAINLY EXPECTING DRY CONDITIONS FOR THE AREA THRU
THE MORNING HOURS.

BY MID DAY...EXPECTING THE COLD FRONT TO HAVE SUNK SOUTH...ALIGNING
WITH THE MD/VA STATE BORDER. DECENT WARMING THIS MORNING AHEAD OF
THE FRONT SHOULD AID IN DESTABILIZING THE ATMO ENOUGH TO TRIGGER SCT
SHOWERS. ISO TSTM PSBL IN THE MIX...THOUGH INSTABILITY IS QUITE
MINIMAL AND LAPSE RATES/SHEAR ON THE WEAKER SIDE. AS SUCH...WILL
MAINTAIN ISO WORDING MIDDAY FOR THUNDER. FOR LATER IN THE AFTN...
INCRSG CHC OF PCPN AT THE PEAK OF DIURNAL HEATING. HOWEVER...
BEHIND THE FRONT EXPECTING A MORE STABLE ATMO AS ELY FLOW SETS UP.
THIS SHOULD LIMIT ANY THUNDER DEVELOPMENT...AND POTENTIALLY ANY
PCPN AT ALL. WILL KEEP SLIGHT CHC POPS OVER NORTHEASTERN PORTIONS
OF THE CWA...WITH THE HIGHER POPS TO THE SOUTH AND WEST. THIS AREA
SHOULD WARM INTO THE 80S...WITH AREAS TO THE NORTH CLOSER TO THE
MASON-DIXON HOVERING IN THE MID-UPPER 70S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
COLD FRONT CONTINUES TO SAG TO THE SOUTH TONIGHT...EVENTUALLY
DISSIPATING BY THURS MORNING. LINGERING PCPN THIS EVENING WILL
TAPER OFF AFTR SUNSET WITH LOSS OF DIURNAL INFLUENCE. DRY WX
SETTING UP BY THE SECOND HALF OF THE NIGHT AS SFC HIGH PRESSURE
OVER NEW ENGLAND BUILDS SOUTH UNDER THE BUILDING RIDGE.

SFC HIGH KEEPS MOST OF THE AREA DRY THEN THURS THRU THURS NIGHT AS
THE RIDGE AXIS SHIFTS EAST...STRADDLING THE CWA. DID MAINTAIN SLIGHT
CHC POPS WEST OF THE BLUE RIDGE WITH MINIMAL INSTABILITY NOTED
COMBINING WITH TERRAIN INFLUENCES OFF THE ELY FLOW. ANY PCPN TAPERS
OFF YET AGAIN FOR THURS NIGHT. ELY FLOW WILL AID IN KEEPING TEMPS
COOLER DURING THE DAY THURS...WITH MOST AREAS IN THE 70S AND ONLY
POCKETS REACHING 80.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
THERES DECENT SYNOP SCALE AGREEMENT THAT LOPRES WL BE SOMEWHERE
ALONG THE CAROLINA COAST FRI WHILE RDGG WL RESIDE ACRS THE CWFA AND
A CDFNT WL BE ACRS THE WRN GRTLKS. CHALLENGE INVOLVES DETERMINING
WHAT HAPPENS NEXT TO THE LOW. DONT BELIEVE IT WL REACH US DIRECTLY.
EVEN IF IT DECAYS TO OUR S UNDER THE MID-LVL RDG...ITS MSTR WL BE
ADVECTED NWD. WHILE THAT WONT AFFECT FRI FCST...IT DOES BECOME A
PLAYER FOR THE WKND. HV INCRSG DEWPTS...NEAR 60F FRI/LWR-MID 60S
SAT- SUN...AND HV INTRO CHC POPS FOR SAT/EXPANDED CVRG SUN.
FURTHER... THERE SHUD BE SUFFICIENT RH FOR ADDED CLDS...AND HV
SOMETHING THAT/LL BE BORDERLINE PTSUN IN THE DATABASE. MAXT SHUDNT
BE FAR FM PERSISTENCE...LWR 80S. BUT THE ANOMOLOUSLY HIGH DEWPTS
SUGGST MIN-T WL BE ON THE MUGGY SIDE. USED THESE DEWPTS FOR A
STARTING POINT FOR MIN-T-- MID 60S FOR SUN/MON ELY MRNGS.

CARRIED THE TROPICAL MSTR FEED INTO MON. SAME CONSIDERATIONS BUT
POPS/TEMPS/DEWPTS A PINCH HIER AS AMS FM THE SERN CONUS ADVECTS ACRS
MID ATLC. AM KEEPING THUNDER IN FCST. INSTBY IMPROVES A LTL VS WKND
FCST. AT THIS POINT NOT SOLD ON ANY STRONG/SVR STORMS THO.

CDFNT PARKED TO OUR W/NW AT THE BGBG OF THE XTNDD FCST WL FINALLY HV
ROOM TO SWEEP EAST BY TUE.  IF THERE WERE ANY STRONG STORMS...THIS
WUD LKLY BE THE DAY. HWVR JURY STILL OUT AS TO MAGNITUDE TO THREAT.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
PATCHY FOG PSBL AT ALL TAF SITES THRU EARLY MORNING...THOUGH
GENERALLY EXPECTING 3-5SM. LEAST CONFIDENCE OF IT OCCURRING AT
KDCA/KBWI/KMTN WHERE CLOUD COVER IS HANGING ON LONGER. VIS IMPROVE
12-13Z...WITH P6SM THEN EXPECTED THRU THE REMAINDER OF THE DAY.

INCRSG MID-HIGH LVL CLOUDS TODAY. GENERALLY EXPECTING VFR THRU
00Z...WITH PSBL STRATUS FORMING TONIGHT WITH THE FRONT STALLING OVER
THE REGION. WILL HINT WITH SCT030 FOR NOW...AND MONITOR THE TREND.

SCT SHOWERS AND ISO TSTMS PSBL AFTR 18Z. CONFIDENCE OF
TIMING/LOCATION TO LOW TO INCLUDE AS -SHRA/TSRA ATTM...SO WILL
MAINTAIN VCSH. ANOTHER DAY OF LIGHT WINDS...MAINLY LESS THAN 8 KTS.
NE FLOW THIS MORNING WILL BECOME ELY FOR THE AFTN THRU TONIGHT. ANY
SHOWER/TSTM COULD BRING A BRIEF PERIOD OF GUSTY WINDS THIS AFTN.

OUTLOOK...
VFR FRI. ISOL-SCT SHRA/TSRA PSBL DAILY SAT-SUN...MAINLY AFTN/EVE.
MAY BE BRIEF FLGT RESTRICTIONS IF A TERMINAL IS IMPACTED. THATS A
LOW CONFIDENCE FCST AT THIS VANTAGE POINT. FURTHER...CUD HV
PREDAWN FOG ASSUMING WET GROUND BEFORE NIGHTFALL FLWD BY PRTL
CLRG. THAT FCST HIGHLY CONDITIONAL.

&&

.MARINE...
GENERALLY SUB-SCA CONDITIONS EXPECTED ON ALL WATERS THRU THURS
NIGHT WITH WEAK PRESSURE GRADIENT IN PLACE. SCT SHOWERS AND TSTMS
THIS AFTN COULD RESULT IN BRIEF PERIODS OF GUSTY CONDITIONS...
MAINLY LATE AFTN AND EVENING TIME FRAME.

WEAK PRESSURE PTTN THRU THE WKND. NO HAZARDS XPCTD ATTM. LOPRES S OF
WATERS MAY EJECT NEWD...PROVIDING BRIEF/LCL SHRA/TSRA BCMG MORE NMRS
BY END OF PD.

&&

.CLIMATE...
THE WARMEST AIRMASS OF THE 2015 SO FAR HAS MOVED OVER THE REGION
DURING THE EARLY PART OF THIS WEEK.

DCA REACHED A HIGH OF 86 DEGREES ON TUESDAY MAY 5TH...THE WARMEST
DAY SINCE SEPTEMBER 21ST 2014 WHEN THE TEMPERATURE REACHED 86
DEGREES.

BWI REACHED A HIGH OF 85 DEGREES ON TUESDAY MAY 5TH...THE WARMEST
DAY SINCE SEPTEMBER 11TH 2014 WHEN THE TEMPERATURE REACHED 89
DEGREES.

IAD REACHED A HIGH OF 85 DEGREES ON TUESDAY MAY 5TH...THE WARMEST
DAY SINCE SEPTEMBER 11TH 2014 WHEN THE TEMPERATURE REACHED 86
DEGREES.

CHO REACHED A HIGH OF 85 DEGREES ON TUESDAY MAY 5TH...THE WARMEST
DAY SINCE SEPTEMBER 21ST 2014 WHEN THE TEMPERATURE REACHED 87
DEGREES.

DMH REACHED A HIGH OF 86 DEGREES ON MONDAY MAY 4TH...THE WARMEST DAY
SINCE SEPTEMBER 11TH 2014 WHEN THE TEMPERATURE REACHED 90 DEGREES.

HGR REACHED A HIGH OF 85 DEGREES ON MONDAY MAY 4TH...THE WARMEST DAY
SINCE SEPTEMBER 6TH 2014 WHEN THE TEMPERATURE REACHED 90 DEGREES.

MRB REACHED A HIGH OF 85 DEGREES ON MONDAY MAY 4TH...THE WARMEST DAY
SINCE SEPTEMBER 21ST 2014 WHEN THE TEMPERATURE REACHED 86 DEGREES.

DCA = REAGAN NATIONAL AIRPORT (WASHINGTON DC) BWI = BALTIMORE-
WASHINGTON THURGOOD MARSHALL INTERNATIONAL AIRPORT IAD = DULLES
INTERNATIONAL AIRPORT CHO = CHARLOTTESVILLE ALBEMARLE AIRPORT DMH =
MARYLAND SCIENCE CENTER (BALTIMORE INNER HARBOR) HGR = HAGERSTOWN
REGIONAL AIRPORT MRB = EASTERN WEST VIRGINIA REGIONAL AIRPORT
(MARTINSBURG WV)

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...DENSE FOG ADVISORY UNTIL 8 AM EDT THIS MORNING FOR VAZ026-027-
     029-038>040-050-051-055-502-507.
WV...DENSE FOG ADVISORY UNTIL 8 AM EDT THIS MORNING FOR WVZ055.
MARINE...NONE.

&&

$$
SYNOPSIS...SEARS/HTS
NEAR TERM...SEARS
SHORT TERM...SEARS
LONG TERM...HTS
AVIATION...SEARS/HTS
MARINE...SEARS/HTS
CLIMATE...


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