Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
000
FXUS61 KLWX 230111
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
911 PM EDT TUE JUL 22 2014

.SYNOPSIS...
HIGH PRESSURE WILL NEAR THE EASTERN SEABOARD TONIGHT. A COLD FRONT
WILL APPROACH FROM THE WEST WEDNESDAY...AND MOVE THROUGH THE
REGION WEDNESDAY NIGHT INTO EARLY THURSDAY. HIGH PRESSURE IS
EXPECTED TO RETURN TO THE REGION TO END THE WORK WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
HIGH PRESSURE CONTS IN THE WRN ATLC OFF THE MID ATLC/CAROLINA
COAST. SHRA HV BEEN LMTD...RELEGATED MAINLY TO THE APLCN RDGS.
WITH THE LOSS OF DAYTIME HEATING...THERE SHUDNT BE MUCH MORE TO
THEIR LIFESPAN. FOR THAT MATTER...CLDS HV BEEN LESS XTNSV THAN
LAST NGT. SINCE THERE/S LESS INFLUENCE FM THE SERN CONUS
DISTURBANCE /DRY AIR AHD OF THE NXT CDFNT HAS BEEN SHUNTED SEWD
OVER CWFA/...THINK THERE WL BE LESS CLDCVR. THAT POSES MORE FOG
CONCERNS INSTEAD. GNLY GOING A MORE OPTIMISTIC RTE...AS PATCHY FOG
HAS BEEN ADDED TO THE MTN/FOOTHILL VLYS...BUT AM KEEPING THE I-95
CRRDR FOG-FREE. WNDS HVNT DCPLD YET...AND THE LGT SLY FLOW/UPR
60S-LWR 70S DEWPTS NOT GREAT FOR RADL COOLING. MAY HV TO NUDGE
MIN-T GRID UPWD DUE TO THOSE DEWPTS.

WEDNESDAY STARTS WITH HIGH PRESSURE EXTENDING FROM THE OFFSHORE
WATERS AND INTO THE CAROLINAS...WITH A COLD FRONT EXTENDING ACROSS
THE LOWER GREAT LAKES AND OHIO VALLEY. THE COLD FRONT WILL
APPROACH DURING THE DAY...WHILE A 500MB TROUGH STRENGTHENS OVER
THE THE SAME REGION. COMBINATION OF INSTABILITY...LIFT AND
MOISTURE IS EXPECTED TO SUPPORT SHOWERS AND THUNDERSTORMS...WITH
ACTIVITY MORE LIKELY OVER NORTHERN AND WESTERN PORTIONS OF THE
FORECAST AREA THAT WILL BE CLOSER TO THE APPROACHING FRONT.
ISOLATED SEVERE STORMS WILL ALSO BE POSSIBLE ACROSS WESTERN MD AND
THE EASTERN WV PANHANDLE...WHICH SHOULD BE IN THE RIGHT ENTRANCE
REGION OF THE JET STREAM BY LATE IN THE DAY. DAMAGING WINDS IS
LIKELY TO BE THE MAIN THREAT.

WEDNESDAY WILL BE THE WARMEST DAY OF THE WEEK...WITH HIGHS IN THE
LOW 90S AT MOST LOCATIONS.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
THE COLD FRONT IS EXPECTED TO MOVE THROUGH MOST OF THE FORECAST
AREA WEDNESDAY NIGHT...AND SHOULD BE EAST OF THE I-95 CORRIDOR BY
THURSDAY MORNING. SHOWER/TSTM ACTIVITY SHOULD SHIFT EWD
ACCORDINGLY. SEVERE THREAT IS UNCERTAIN...AS BETTER DYNAMICS WILL
BE OFFSET BY LOWER NIGHTTIME INSTABILITY. LOWS RANGE FROM THE MID
60S OVER EASTERN WV...BEHIND THE FRONT...TO THE MID 70S ALONG AND
EAST OF I-95.

COLD FRONT MOVES EAST OF THE REGION ON THURSDAY...WHILE AN UPPER
TROUGH APPROACHES FROM THE WEST. SHOWER/TSTM CHANCES CONTINUE WITH
COOLER AIR ALOFT...BUT WITH A N-NW FLOW CHANCE OF SEVERE WX IS
UNLIKELY AT THIS TIME. TEMPS WILL BE COOLER WITH HIGHS RANGING
FROM THE UPPER 70S OVER HIGHER ELEVATIONS TO THE MID 80S ELSEWHERE.

UPPER TROUGH MOVES THROUGH THURSDAY NIGHT...WITH DRY CONDITIONS
EXPECTED EXCEPT POSSIBLY OVER SRN MD AND PORTIONS OF THE PIEDMONT.
LOWS DROP INTO THE 50S AND 60S.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
A RIDGE OF HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST FRIDAY AND
FRIDAY NIGHT TO ALLOW COOLER AND DRIER AIR TO PUSH INTO THE REGION
THROUGH SATURDAY.

WITH THE HIGH MOVING TO THE COAST AND OFFSHORE DURING THE DAY
SATURDAY...SOUTHEAST TO SOUTHERLY WINDS WILL EVOLVE...THUS PERHAPS
SPAWNING A SHOWER IN THE POTOMAC HIGHLANDS WITH THE UPSLOPE
COMPONENT.

DISTURBANCES IN THE UPPER LEVELS WILL ROTATE IN FROM THE OHIO VALLEY
AND LOWER GREAT LAKES SATURDAY NIGHT AND SUNDAY...THUS...BRINGING
THE CHANCE FOR SHOWERS AND THUNDERSTORMS.

AS FOR SUNDAY NIGHT THROUGH TUESDAY...A POTENT UPPER LEVEL STORM
SYSTEM WILL LINGER ACROSS THE GREAT LAKES REGION. SEVERAL WAVES OF
ENERGY WILL ROTATE AROUND IT AND ACROSS THE MID ATLANTIC REGION. THE
CHANCE OF SHOWERS AND THUNDERSTORMS...ONCE AGAIN...WILL BECOME A
NUISANCE TO THE REGION.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
VFR MOST OF THE NIGHT...BUT MVFR VSBYS WITH FOG IS POSSIBLE LATE
TONIGHT INTO THE EARLY MORNING HOURS WITH MOIST AIR OVER THE
REGION. HV CONFINED THE VSBY RESTICTIONS TO CHO-MRB...AWAY FM THE
HUBS. ITS NOT BYD THE REALM OF PSBLTY THAT MVFR VSBYS CUD OCCUR AT
IAD TOO...OR THAT MRB-CHO MAY BRIEFLY DROP TO IFR.

SCATTERED SHOWERS AND TSTMS POSSIBLE WED AFTN INTO EARLY THU. AN
OFFSHORE HIGH WILL PUSH UP THE HEAT/HUMIDITY BEFORE TSTMS
ARRIVE/DEVELOP...WHILE A COLD FRONT APPROACHES FROM THE NW. THE
FRONT WILL LIKELY MOVE ACROSS THE AREA LATE WED INTO EARLY
THU...SWEEPING THIS ACTIVITY OFF THE COAST BY LATE THU AFTN.

VFR CONDITIONS WITH LIGHT AND VARIABLE WINDS EXPECTED FRIDAY
THROUGH SATURDAY AT ALL TERMINALS.

&&

.MARINE...
SLY CHANNELING HAS COME UP THE CHSPK BAY...PLACING TPLM2 AT THE
DOORSTEP OF SCA. WRF-ARW4 HAS BEEN STRONGER THAN THE REST...AND
LTST RUNS HV BEEN STRONGER STILL...BUT EVEN IT SUGGESTING THAT THE
PEAK OCCURRING ATTM...W/ WNDS BLO ANY CRIT LVL BY 02-03Z.
THEREFORE...OPTED FOR MARINE WX STMT VS A TARGETED SCA.

SLY WNDS ARND 10 KT FOR THE OVNGT HRS.

LIGHT S-SW FLOW WILL CONTINUE WEDNESDAY AND MAXIMIZE JUST BEFORE THE
PASSAGE OF A COLD FRONT EARLY THU. SHOWERS AND TSTMS POSSIBLE WED
EVE INTO THE OVERNIGHT.

NO MARINE HAZARDS EXPECTED FRIDAY THROUGH SATURDAY.

&&

.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES DROPPED TO AROUND A HALF-FOOT EARLIER TODAY...AND
REMAIN THERE ATTM. THOSE DEPARTURES...IF STEADY...WOULD POSE NO
CONCERN DURING HIGH TIDE TONIGHT...EVEN AT SENSITIVE LOCATIONS.
HOWEVER...AM NOT CERTAIN WHETHER DEPARTURES WONT BE INCREASING
AGAIN WITH THE INCOMING TIDE CONSIDERING THE 15 KT SLY FLOW THAT
HAS DVLPD ON THE BAY THIS EVNG. BASED ON LOW CONFIDENCE AND LOW
IMPACT /IT WOULD BE A THRESHOLD EEVNT AT ANNAPOLIS/...HAVE OPTED
TO NOT ISSUE AN ADVY AT THIS TIME.

&&

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

&&

$$
SYNOPSIS...KCS
NEAR TERM...HTS/KCS
SHORT TERM...KCS
LONG TERM...KLW
AVIATION...HTS/KCS/KLW
MARINE...HTS/KCS/KLW
TIDES/COASTAL FLOODING...HTS






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.