Relay, Maryland Forecast Discussion

000
FXUS61 KLWX 300740
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
340 AM EDT FRI JUL 30 2010

.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO PUSH SOUTHEAST OF THE REGION THIS
MORNING AS HIGH PRESSURE BUILDS. THE HIGH WILL CREST OVER THE
NORTHEAST EARLY SATURDAY...AND THEN PUSH OFFSHORE. THE SUBSEQUENT
SOUTHEASTERLY FLOW AND AN UPPER LEVEL DISTURBANCE WILL LEAD TO
POSSIBLE UNSETTLED CONDITIONS SATURDAY NIGHT AND SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 07Z...THE COLD FRONT THAT BROUGHT UNSETTLED CONDITIONS TO THE
AREA YESTERDAY HAS JUST ABOUT CLEARED THE ENTIRE CWA WITH THE
EXCEPTION OF LOWER SRN MD...WHERE DEWPOINTS STILL REMAIN AROUND 70F.
THE FRONT WILL PUSH SOUTH OF THE AREA BEFORE DAYBREAK. N-NW FLOW
BEHIND THE FRONT WILL CONTINUE TO USHER IN MUCH DRIER AND COOLER AIR
INTO THE REGION. THIS FROPA WAS MORE REPRESENTATIVE OF LATE SPRING
AS DEWPOINTS DROPPED 10-15 DEGREES WITHIN A COUPLE HRS.

TDA WILL BE ONE OF THE FEW PLEASANT DAYS THIS SUMMER WITH A RELIEF
FROM THE HEAT AND HUMIDITY. DESPITE THE ABUNDANT SUNSHINE...HIGHS
WILL ONLY BE IN THE 80S. TDA WOULD ONLY BE THE 9TH /10TH/ DAY SO
FAR THIS MONTH THAT DCA /BWI/ HAS FAILED TO REACH 90F. THIS IS THE
LEAST FREQUENT AMOUNT OF DAYS BELOW 90F AT DCA AND BWI IN JULY SINCE
1999...WHEN 9 DAYS WAS TALLIED AT BOTH LOCATIONS. THE LEAST NUMBER
OF DAYS BELOW 90F AT DCA /BWI/ IN JULY ON RECORD IS 7 /9/ BACK IN
1987 AND 1993 /1988 AND 1999/.

WITH LOW DEWPOINTS...MSTLY CLEAR SKIES AND CALM WINDS...OVNGT TEMPS
WILL BE THE COOLEST SINCE THE FIRST FEW DAYS OF THIS MONTH. LOW
TEMPS WILL RANGE FROM THE 50S ALONG AND WEST OF THE BLUE RIDGE TO
60S FARTHER EAST. A FEW LOCATIONS IN RIDGE TOPS OF POTOMAC HIGHLANDS
MAY FLIRT WITH THE 50 DEGREE MARK...DEPENDING ON HOW MUCH CLOUD
COVER MOVES IN LATE.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
WKND FCST STILL CONTAINS A FAIR AMT OF UNCERTAINTY...MAINLY WRT
PLACEMENT/STRENGTH OF IMPULSES W/IN H5 MEAN TROF AND ANY POTL LLVL
DVLPMNT. THE GDNC SPREAD MAGNIFIES BY LT SUN...EVIDENCED BY SREF STD
DEV. ATTM...FEATURES APPEAR TOO WK...AND AM PLAYING A MIDDLE OF THE
ROAD APPROACH IN THE FCST.

SAT DAYTIME CUD VERY WELL END UP DRY...AS SFC HIPRES STILL NEARBY...
AND RTN FLOW YET TO RSLT IN SGFNT MSTR POOLING. THAT/S THE BIGGEST
CHG MADE TO GRIDS. DEWPTS ONLY STARTING TO COME UP...THO HV INCRSD
CLDCVR /BOTH LOW AND HIGH/ SUPPORTED BY MDL SNDGS.

DONT THINK WE/LL MAKE IT THRU SAT NGT DRY THO...AS MOIST SELY LLVL
FLOW AND H8 WAA COMBINE W/ TRRN TO PRODUCE SUFFICIENT LIFT. UVV ONLY
INCREASES SUN AS INSTBY MAXIMIZED DUE TO INSTBY FM DIURNAL HTG AND
AN ADDED KICK FM PVA. DID NOT ATTEMPT TO TIME DETAILS W/IN GRIDS--
KEPT CHC /MOSTLY 40 PCT/ POPS FOR SAT NGT AND LKLY /MOSTLY 60 PCT/
POPS SUN.

TEMP FCSTG WL ALSO BE A CHALLENGE...AS IT WL BE DICTATED BY PCPN
CHCS. CURIOUSLY...GFS/NAM NOT TOO FAR OFF DESPITE DIFF SYNOPTIC
SOLNS. LARGEST SPREAD COMES MAXT SAT INVOF THERMAL TROF. GOING
MID-PACK YIELDS MID-UPR 80S SAT...AND A CPL DEGF COOLER ON SUN.
&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
ZNL FLOW WITH RETURN TO SEASONABLE SUMMER WX FOR ERY NEXT WEEK. CANT
RULE OUT ISOLATED MAINLY DIURNAL CNVCTN. MAXIMA RETURN TO AOA
90F...WITH MINIMA IN U60S/L70S.
&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS TDA AND TNGT. N TO NW WINDS AROUND 10 KT DURING THE
DAY TDA...BECOMING LIGHT BY SUNSET.

LOW CONFIDENCE WKND FCST. SAT WL START OUT VFR...THEN POTENTIALLY
CUD BE HEADING DOWNHILL...SPCLY SAT NGT-SUN IN RESPONSE TO MID LVL
DISTURBANCE. STILL PLENTY OF TIMING/STRENGTH QSTNS. MON-TUE FCST
REVERTS TWD CLIMO.
&&

.MARINE...
SCA FOR THE MD CHSPK BAY AND THE MOUTH OF THE TIDAL POTOMAC RIVER
WILL CONTINUE THRU THE MRNG. NLY SURGE BEHIND THE FRONT WILL CHANNEL
DOWN THE BAY...ALLOWING FOR A GUSTS AROUND 20 KT. SUCH NLY SURGE IS
ALREADY BEING OBSERVED ACROSS THE NRN HALF OF THE BAY...AND SHOULD
PROGRESS FARTHER SOUTHWARD ERY THIS MRNG. WINDS WILL RELAX BY THIS
AFTN AS HIPRES BUILDS OVRHD.

NO HEADLINES REST OF FCST. HIPRES PASSES OFFSHR SAT...RSLTG IN
VEERING FLOW FM N TO SELY. S/SELY WNDS WL CONT INTO ELY NXT WK. SAT
NGT-SUN CUD BE UNSTTLD AS DISTURBANCE PASSES NEARBY. ATTM...GDNC
YIELDS MORE QSTNS THAN ANSWERS.
&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR ANZ530>534-
     537>543.

&&

$$
SYNOPSIS...HTS
NEAR TERM...JRK
SHORT TERM...HTS
LONG TERM...SBK
AVIATION...JRK/HTS
MARINE...JRK/HTS

NWS LWX Office Area Forecast Discussion