Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 300801
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
401 AM EDT SAT MAY 30 2015

.SYNOPSIS...
HIGH PRESSURE WILL PERSIST OFFSHORE TODAY WITH CONTINUED WARM AND
HUMID CONDITIONS IN THE MID-ATLANTIC. A COLD FRONT WILL ENTER THE
REGION LATE SUNDAY AND STALL OVER THE REGION INTO TUESDAY. HIGH
PRESSURE IS EXPECTED TO SLIDE INTO THE REGION FOR THE MIDDLE PART
OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...

RDG OF HIPRES OFF THE ATLC COAST EXTENDS WWD TO INCL THE ERN
SEABOARD. THE NEAREST FNT STRETCHES ACRS THE GRTLKS...W/ AN AREA OF
LOPRES IN THE S-CENTRAL CONUS. WHILE THE AMS IS WARM AND HUMID...A
SUBSTANTIVE TRIGGER IS LACKING. THAT SAID...A FEW SHRA HV MANAGE TO
DVLP ELY THIS MRNG...AND WRF/RAP GDNC SUGGESTS THAT MAY CONT TO BE
PSBL. PINPOINTING DVLPMNT QUITE RANDOM...AND WUD RATHER GO W/ A DRY
FCST TO START UNLESS FORCED OTRW BY CONDS. PATCHES OF FOG WL BE MORE
PREVALENT...DVLPG IN ANY CLR SPOTS IN THE CLDCVR.

AFTER SUNRISE...DECENT INSTBY DOES DVLP...BUT LIKE PAST CPL DAYS
IT/LL BE MITIGATED BY WARM MID-LVLS. HGTS WL BE SLGTLY LWR IN THE
MTNS...WHICH WL ALSO HV TRRN SUPPORT AND PERHAPS A PINCH OF SHEAR.
SCT TSRA ACTIVITY SHUD DVLP W/ INSOLATION. THE STRONGER STORMS MAY
CARRY A HIGH WIND THREAT...BUT WUD THINK THAT WUD BE THE XCPTN. PWAT
UP TO 1.5 INCHES SUGGEST THAT THE MAIN THREAT WUD BE HVY RAIN.

WARMER GFS HAS BEEN PERFORMING BETTER FOR MAXT...AND SIDED IN THAT
DIRECTION. SINCE DEWPTS WL REMAIN MID 60S ON AVG...WEIGHTED TWD HIER
MET MOS FOR MIN-T TNGT.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...

MS VLY LOPRES EXERTING A HEAVIER INFLUENCE IN SYNOP EVOLUTION
SUNDAY...WHICH SLOWS DOWN CDFNT AND STALLS PTTN CHG. A SHARPENING
TROF W OF THE APLCNS IN TURN SUPPORTS CONTD RDGG IN THE ATLC COAST.
THAT PLACES CWFA IN WARM/HUMID AMS FOR YET ANOTHER DAY...W/ THE
UNSTBLTY THAT GOES WITH IT. INVOF THE LOW...SHEAR SHUD BE A BIT
BETTER...WHICH WL BE WHERE GREATER CHC OF STRONG TSTMS RESIDES. BUT
THE FORCING OF THE FNT WL BE SUFFICIENT TO PROMPT STORM DVLPMNT...
ALBEIT A BIT LATER THAN PRVSLY ADVERTISED. HV TRIMMED POPS FOR THE
DAYTIME PD...BACKING OFF INTO THE CHC CATEGORY FOR EAST OF THE
BLURDG. BUT AMPLE MSTR STREAMING FM WRN GLFMEX WL MAINTAIN HIGH PCPN
RATES W/IN THESE STORMS.

TSRA WL EMERGE EAST OF THE BLURDG SUN EVE...PRECEDING THE FNT.
XPCT A LTL BIT OF WEAKENING DUE TO LOSS OF DAYTIME HEATING AS WELL
AS A SLGTLY LESS FVRBL ENVIRONMENT. DO NOT HV A GOOD FEEL FOR
WHETHER ACTIVITY WL CONT OVNGT OR NOT. HV MAINTAINED CHC POPS
THRUT.

LIKE SAT...STUCK TO THE WARMER END OF GDNC FOR TEMP FCSTG. THAT
YIELDS A SIZEABLE ADJUSTMENT TO THE SUN NGT LOW.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
LOW PRESSURE SHOULD BE IN THE VICINITY OF CENTRAL NY/PA MONDAY
MORNING WITH A COLD FRONT EXTENDING SOUTH BISECTING THE MID-
ATLANTIC. THE DETERMINISTIC GFS AND ECMWF ARE IN AGREEMENT THAT THE
COLD FRONT WILL SLOWLY MOVE EASTWARD MONDAY AFTERNOON. TEMPS WILL
LIKELY RISE INTO THE UPPER 60S TO MID 70S WEST OF THE BLUE RIDGE AND
INTO THE UPPER 70S TO NEAR 80 AROUND THE I-95 CORRIDOR. SUBTLE
CHANGES IN THE PLACEMENT OF THE FRONT MONDAY MORNING WILL IMPACT THE
TEMP FORECAST FOR SOME LOCALES. STRONG MOISTURE ADVECTION ALONG THE
FRONT WILL LEAD TO HEAVY RAIN AT TIMES AND INSTABILITY WILL INCREASE
AHEAD OF THE FRONT MONDAY AFTERNOON. THUNDERSTORMS WILL BE POSSIBLE
DURING THIS TIME. BEST CHANCE FOR STRONG TO SEVERE THUNDERSTORMS
WILL BE NEAR THE HIGHER TEMPS AND DEWPS...ACROSS THE PIEDMONT...
SOUTHERN MARYLAND AND SURROUNDING WATERS. HEAVY RAIN MAY CAUSE
LOCALIZED FLOODING MAINLY EAST OF THE BLUE RIDGE MONDAY.

THE FRONT SLOWLY MOVES EASTWARD MONDAY NIGHT. SHOWERS AND
THUNDERSTORMS MAY PERSIST NEAR THE I-95 CORRIDOR AND EAST INTO
TUESDAY MORNING. BEHIND THE FRONT...COOL AND DRY AIR WILL FILTER
INTO THE REGION. THE COLD FRONT SHOULD BE OFF THE COAST BY TUESDAY
AFTERNOON. A FEW LINGERING SHOWERS POSSIBLE NEAR THE CHESAPEAKE BAY
ARE POSSIBLE. TEMPS SHOULD BE IN THE 70S TUESDAY WITH A FEW SPOTS
NEARING 80 IN THE PIEDMONT AND FOOTHILLS.

HIGH PRESSURE EXPECTED MID WEEK WITH NRLY WINDS KEEPING TEMPS COOLER
THAN THE RECENT WEEKS. TERRAIN INDUCED SHOWERS AND THUNDERSTORMS ARE
POSSIBLE IN THE AFTERNOON TOWARDS THE END OF THE WEEK. TEMPS SHOULD
STAY AROUND 80 DURING THIS TIME.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...

AREAS OF FOG BGNG TO DVLP...IMPACTING THE MRB TAF. HAD FCST AT
MVFR...THINKING THAT THE BEST CHC AT LWR FLGT RESTRICTIONS WUD BE IN
CENTRAL VA-- RMVD FROM ANY TERMINALS. BASED ON GOING MTRS...MAY NEED
TO CONSIDER LCL IFR VSBYS THRU SUNRISE.

VFR SHUD PREVAIL FOR THE DAYTIME PD. SCT TSRA SHUD DVLP. MRB WUD HV
THE GREATEST CHC AT SEEING ONE. WHILE BRIEF MVFR/IFR PSBL...
DURATION TOO LIMITED AND PLACEMENT TOO UNCERTAIN TO MENTION IN ANY
TAF ATTM. INSTEAD HV SCT-BKN CU DVLPG...BASES 050. SLY FLOW WL INCR
TO 10-15 KT.

ONCE AGAIN...AREAS OF FOG SHUD BE DVLPG LT TNGT...SPCLY WHERE ANY
TSRA PASSED THRU DURING THE DAY. LCL IFR PSBL.

TSRA SHUD BE MORE NMRS SUN...TIMING A BIT LATER THAN PRVSLY THOUGHT.
AFTN-EVE HRS WL BE PREFERRED...BUT CAN NOT RULE OUT AN OVNGT STORM.

SUB-VFR CONDITIONS POSSIBLE MONDAY ESPECIALLY AT CHO-DCA-BWI-MTN
WHERE CONFIDENCE IS HIGHER THAT HEAVY RAIN WILL CAUSE LOW VSBYS.
WINDS BECOME W-NW MONDAY AFTERNOON.

&&

.MARINE...

SLY CHANNELING HAS BROUGHT SCA CONDS TO THE MAIN CORE OF THE MD
CHSPK BAY. WRF GDNC SUGGESTS ITLL DIMINISH BY SUNRISE.

SLY FLOW TO PREVAIL THIS WKND. EACH DAY WINDS WL BE INCREASING W/
DAYTIME MIXING...BRINGING THE MD BAY/INLETS UP TO THE CUSP OF SCA
CRITERIA. HV ISSUED A PAIR OF ADVYS TO COVER THE AFTN-EVE HRS. TSRA
SHUD BE SPARCE ON SAT...MORE NMRS ON SUN. SOME STORMS WL CARRYING A
LCL HIGH WIND RISK...AND SMW/S WL BE PSBL. BUT THE CDFNT WL BE
DELAYED...AND S/SWLY FLOW WL DOMINATE THRU THE WKND.

S-SW WINDS EXPECTED ON THE WATERS MONDAY AS A COLD FRONT NEARS. SCA
CONDITIONS ARE POSSIBLE MONDAY AND AGAIN ON TUESDAY AS THE COLD
FRONT CROSSES THE WATERS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 2 AM EDT SUNDAY FOR
     ANZ530>534-537>543.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     ANZ531>533.

&&

$$
SYNOPSIS...HTS
NEAR TERM...HTS
SHORT TERM...HTS
LONG TERM...HAS
AVIATION...HAS/HTS
MARINE...HAS/HTS


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