Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 290731
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
331 AM EDT SAT AUG 29 2015

.SYNOPSIS...
HIGH PRESSURE REMAINS OVER THE REGION THROUGH SUNDAY AND THEN SLIDES
OFFSHORE THROUGH THE END OF THE NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
SFC HIPRES ATOP THE MID ATLC ATTM. IN SPITE OF THIS...A THIN MOIST
LYR AT 5K FT SENDING SOME BKN CLDS ACRS THE CWFA. AS A RESULT...
TEMPS RUNNING A LTL WARMER THAN PROGGED...AND FOG IS FAR LESS.
SUSPECT WE/LL SEE SOME CLRG PRIOR TO DAWN...AND HV KEPT THE PSBLTY
OF A PINCH OF FOG IN THE VLYS OF THE PIEDMONT...BUT DONT BELIEVE
IT/LL BE ALL THAT MUCH.

THE DAYLIGHT HRS TDA WL BE VERY SIMLR TO THE PRVS SVRL DAYS...ASIDE
FM SUBTLE WAA/DEWPT ADVCTN. WHILE NOT UNSTBL...AMS MAY BE ABLE TO
SUPPORT A CPL SHRA /TSRA?/ WITH THE SUPPORT OF TRRN CIRCULATIONS IN
THE APLCNS. WL BE FOCUSING ON THE HIER PEAKS /HIGHLAND-PENDLTN
CNTYS/ TIL SUNSET.

DIURNAL CU SHUD BE DSPTG DURING THE EVNG HRS...AND STILL BELIEVE
THAT THE OVNGT HRS WL BE MAINLY CLR. SINCE DEWPTS WL BUMP UP INTO
THE LWR 60S AND WINDS WL ONCE AGN DCPL...STAGE SHUD BE SLGTLY BETTER
FOR PATCHY FOG. AM STICKING W/ CLIMO...FAVORING THE PIEDMONT/SHEN
VLY/PTMC HIGHLANDS.

PTTN THUS FAR HAS FAVORED A MAV/EURO MAXT OUTPUT...AND WL EMPLOY
THAT SOLN WHILE MAINTAINING A FRACTION OF CONTINUITY FM PREV FCST.
MIN-T FCST WL BE A BLEND OF A MORE DIVERSE GDNC MEMBERSHIP.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
H5 HGTS LESS ACRS THE GRTLKS/OHVLY/MID MS VLY AS A CUTOFF LOW
MEADERS NORTH. THIS WEAKNESS WL SUPPORT GREATER LAPSE RATES AND THUS
A BIT MORE INSTBY THAN PRVS DAYS. HARD TO TELL IF THERE WL BE A
CDFNT W/IN THIS ZONE OR NOT. EVEN IF THERE IS...IT WONT MAKE IT TO
THE CWFA. INSTEAD...GRDLY XPCT MORE WARMTH AND HUMIDITY TO
INFILTRATE AREA. THERMAL CHGS SUBTLE...AND THAT IS REFLECTED IN FCST
GRIDS. MANY SITES ALONG I-95 CRRDR MAY REACH 90F SUN AFTN...IN SPITE
OF MORE CLDCVR.

THE LARGER CHG WL BE TO THE POPS. SINCE THERE WL BE MORE SUPPORT FOR
RANDOM DIURNAL CNVCTN...HV HIER POPS FCSTD...SPCLY ACRS THE RDGS. HV
GNLY KEPT THIS THREAT W OF THE BLURDG /CHC POPS/...ALTHO SKIES WL BE
PTSUN AT BEST ACRS ENTIRE ARE DURING A PORTION OF THE AFTN HRS. RDGG
PARKED SE OF CWFA SHUD PREVENT STORMS FM ADVCG OUT OF THE MTNS.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
SFC HIGH PRESSURE TO OUR EAST WILL TEND TO DOMINATE THE WEATHER
PATTERN DURING THE LONG TERM...WITH DAY-TO-DAY WEATHER INFLUENCED BY
ITS POSITIONING AND MID/UPPER LEVEL DISTURBANCES MOVING THROUGH/NEAR
THE REGION. OVERALL...TEMPERATURES WILL REMAIN A FEW DEGREES AOA
CLIMO NORMS...HUMIDITY WONT BE BE TOO HIGH...AND BENEFICIAL RAIN
CHANCES APPEAR LOW.

MON...MID/UPPER VORT MAX OVER GULF STATES WILL RIDE ALONG THE
PERIPHERY OF RIDGE OVER ATLANTIC AND IMPACT MID-ATLANTIC EARLY IN
THE DAY. IT GETS SHEARED APART AND WEAKENS AS IT IS ABSORBED INTO
NORTHERN STREAM. TIMING OF FEATURE AND POOR LAPSE RATES...RESULTING
FROM NEARLY MOIST ADIABATIC PROFILES ABOVE THE LCL...WILL LIKELY
LIMIT ACTIVITY TO MAINLY SHOWERS EAST OF THE BLUE RIDGE...WITH
PERHAPS A FEW ISOLATED THUNDERSTORMS OVER THE HIGHER TERRAIN.

TUE/WED...POOR LAPSE RATES CONTINUE...WHICH WILL KEEP ISOLATED
DIURNAL CONVECTION CONFINED MAINLY TO HIGHER TERRAIN AND OUR
SOUTHWEST...WHERE TERRAIN CIRCULATIONS PROVIDE ADDED LIFT AND
SLIGHTLY BETTER MOISTURE RESIDES.

THU/FRI...WEAK HEIGHT FALLS AND STEEPENING LAPSE RATES WILL LEAD TO
BETTER...THOUGH STILL LOW...CHANCES FOR DIURNAL CONVECTION ACROSS
ENTIRE CWA.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDS WL PREVAIL OVER THE VAST MAJORITY OF THE TAF PD. FOG PSBL
CHO BEFORE DAWN...AND HV A CPL HRS OF MVFR TO ACCT FOR IT. CANT
COMPLETE RULE OUT MRB TOO...BUT CONFIDENCE IN DETAILS RATHER LOW.
NEED TO GET RID OF CURRENT CLDCVR. BELIEVE THAT CAN HAPPEN.

LGT SLY FLOW TAFTN-EVE W/ DIURNAL CU BASED NEAR 050. CIGS SHUD HOLD
ACRS THE MTNS. THERE MAY BE A STRAY STORM...BUT THAT SHUD STAY CLR
OF THE TERMINALS.

ANTHR ROUND OF POTL FOG PREDAWN SUN. AGAIN...CONFIDENCE IN DETAILS
LACKING. WUD KEEP IT AWAY FM THE HUBS THO.

DIURNAL CU WL DVLP ONCE AGN SUN AFTN-EVE...W/ SLGTLY GREATER CVRG OF
SHRA/TSRA IN THE MTNS. MRB MAY BE CLIPPED BY ONE OF THESE. NO IMPACT
XPCTD FOR BALT-WASH HUBS.

OUTSIDE OF PATCHY PREDAWN FOG...VFR CONDITIONS EXPECTED MONDAY AND
TUESDAY...WITH ISOLATED CONVECTIVE ACTIVITY MAINLY CONFINED TO
APPALACHIANS AND AWAY FROM MOST TERMINALS...EXCEPT CHO. WHILE
LOW...CHANCE FOR BRIEF SUB-VFR AT ALL TERMINALS OCCURS WEDNESDAY
WITH AFTERNOON THUNDERSTORMS.

&&

.MARINE...
SLY FLOW ON THE WATERS ELY THIS MRNG...MOSTLY AOB 10 KT. SLY FLOW WL
CONT THRU THE WKND...ALTHO AN ONSHORE COMPONENT LKLY WL DVLP EACH
AFTN. SIMILARLY...SLY CHANNELING WL LKLY INCR OVNGT. AT THIS
POINT...WL KEEP WINDS UNDER SCA THRESHOLDS.

WINDS EXPECTED TO REMAIN BELOW SCA THROUGH THE REMAINDER OF THE
PERIOD. THUNDERSTORM CHANCES BEGIN TO INCREASE BY MIDWEEK OVER THE
WATERS.

&&

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

&&

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



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