Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 070127
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
927 PM EDT MON JUL 6 2015

.SYNOPSIS...
A WEAK LOW PRESSURE SYSTEM AND WARM FRONT WILL LIFT NORTHEAST OUT
OF THE AREA TONIGHT. HIGH PRESSURE WILL DOMINATE TUESDAY. A COLD
FRONT WILL MOVE IN FROM THE GREAT LAKES ON WEDNESDAY. THE FRONT
WILL SLIDE SLOWLY SOUTH ACROSS THE AREA THURSDAY AND FRIDAY BEFORE
SLOWLY MOVING BACK NORTH OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TUESDAY/...
IT TOOK A WHILE TO GET TOGETHER...BUT A LINE OF STORMS JUST W OF
THE BAY ATTM. WEAK SHEAR AND POOR MID LVL LAPSE RATES PRECLUDED
SVR POTL. BUT PWAT NEAR 1.75 INCHES LED TO HVY RAINERS. SVRL OF
THESE STORMS TRAINING...WHICH IS WHAT HAS PROMPTED FLASH FLOOD
WRNGS.

BASED ON CURRENT EXTRAPOLATION...STORMS SHUD CLEAR CWFA BTWN 02-03
UTC. WITH LOSS OF DAYTIME HEATING/RESULTING INSTABILITY...DO NOT
FORSEE MUCH RDVLPMNT. COULD SEE LINGERING SHOWERS THRU THE NIGHT
AS THE TROUGH PIVOTS TO THE EAST AND NORTH. DO PLAN ON RETOOLING
POP GRIDS FOR THE OVNGT PD...CUTTING BACK ON PCPN CHCS. HWVR...WET
GRND AND PRTL CLRG MAY LEAD TO AREAS OF FOG. WUD NOT RULE OUT LCL
DENSE FOG...BUT DONT HV HIGH CONFIDENCE IN IT EITHER. WL LET AREAS
COVER IT FOR NOW.

TUESDAY LOOKS TO BE RELATIVELY DRY AS THE UPPER LVL TROUGH PUSHES
TO THE NORTH. PCPN PSBL OVER THE NORTHEASTERN CORNERS OF THE CWA
WHERE THE SOUTHERN EDGE OF THE TROUGH WILL HOVER THRU MOST OF THE
DAY. AT THE SFC...LOW PRESSURE TREKKING THRU THE GREAT LAKES WILL
DRAG THE ASSOCIATED COLD FRONT NEAR THE REGION...REACHING THE
WESTERN AREAS OVERNIGHT TUES. CHC OF PCPN WILL ACCOMPANY THE
FRONT.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
HIGH PRESSURE SLIDES EAST TO OUR SOUTH TUESDAY NIGHT AS COLD FRONT
APPROACHES FROM THE NORTHWEST. THE FRONT WILL CROSS INTO THE CWA
BY WEDNESDAY NIGHT. CLOUDS WILL START TO INCREASE TUESDAY NIGHT BUT
THINK MOST SHOWERS OR STORMS HOLD OFF UNTIL DURING THE DAY
WEDNESDAY. MAIN ISSUE WEDNESDAY ARE SOME TIMING DIFFERENCES WITH
THE FRONT. THE SLOWER GUIDANCE KEEPS THE STORMS AWAY EARLY ON AND
ALLOWS TEMPS TO SPIKE INTO THE 90S...WHILE FASTER MODELING BRINGS
STORMS IN EARLY ON WEDNESDAY AND KEEPS TEMPS DOWN IN THE 80S.
EITHER WAY...STORMS SHOULD DIMINISH OR MOVE AWAY WEDNESDAY NIGHT
WITH MODESTLY COOLER TEMPERATURES AND LOWER DEW POINTS.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
FRONTAL BOUNDARY WILL LINGER AROUND THE REGION THU INTO FRI.
UPPER LEVEL DISTURBANCES WILL IMPACT THE CWA ON THE WEEKEND AND
INTO NEXT WEEK. ISOLATED/SCATTERED SHOWERS AND/OR TSTMS ARE PSBL
EACH DAY. TEMPS WILL BE NEAR NORMAL FOR THIS TIME OF THE YEAR.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
TSRA IMPACTS AT BWI/MTN ATTM. MOST LKLY THREAT FOR THE REST OF THE
TERMINALS HAS ENDED. HUMID AIR AND WET GRND DOES LEAD TO A
PREDAWN FOG THREAT. AT THIS TIME HV LIMITED TO MVFR IAD/CHO/MRB.
IF SKIES REMAIN MOCLR...IFR WELL WITHIN REASON.

ANY MRNG FOG WL BURN OFF DURING THE MRNG PUSH. REST OF THE DAY
SHUD BE VFR. WHILE TSRA THREAT NOT ZERO...ITS VERY LOW...AND WAS
NOT MENTIONED IN TAFS.

MAIN CONCERN WEDNESDAY/WEDNESDAY NIGHT HAS TO DO WITH APPROACHING
COLD FRONT. THUNDERSTORMS LOOK LIKELY...WITH A FEW PERIODS OF SUB-
VFR CIGS/VIS AND PERHAPS A FEW STRONG WIND GUSTS MIXED IN WITH
OTHERWISE VFR CONDITIONS. TIMING IS STILL IN QUESTION HOWEVER.
WINDS SHIFTING FROM SOUTHWEST EARLY TO NORTHWEST BY WEDNESDAY
NIGHT...POSSIBLY SOME NON-STORM GUSTS INTO THE 20 KNOT RANGE.

VFR CONDITIONS EXPECTED FOR THU NIGHT AND FRI. SUB-VFR CONDITIONS
PSBL DUE TO SHOWERS AND/OR TSTMS.

&&

.MARINE...
WINDS HV BEEN SUSTAINED 15 KT OR LESS THUS FAR TNGT. HWVR...SETUP
CONDUCIVE FOR SLY CHANELLING. SCA REMAINS IN EFFECT THRU TONIGHT
WITH GUSTS UP TO 20 KTS PSBL. MAINLY SUB- SCA CONDITIONS ON
TUES...THOUGH OCNL GUST UP TO 20 KTS MAY BE PSBL ON THE CHESAPEAKE
BAY. WINDS ARE TOO MARGINAL ATTM TO UP ANOTHER SCA.

MAIN CONCERN WEDNESDAY/WEDNESDAY NIGHT HAS TO DO WITH APPROACHING
COLD FRONT. WINDS WILL PICK UP AHEAD OF THE FRONT WITH GUSTS
POSSIBLY REACHING SCA LEVELS. IN ADDITION...THUNDERSTORMS LOOK
LIKELY...WITH SOME STRONGER GUSTS AND HEAVY RAIN ETC. TIMING IS
STILL IN QUESTION HOWEVER. WINDS SHIFTING FROM SOUTHWEST EARLY TO
NORTHWEST BY WEDNESDAY NIGHT.

SUB-SCA CONDITIONS EXPECTED FOR THU NIGHT AND FRI. PSBL SHOWERS
AND TSTMS ACROSS THE WATERS DURING THIS PERIOD.

&&

.TIDES/COASTAL FLOODING...
WATER LVLS RUNNING ABT 1/2 TO 3/4 FT ABV NRML. THE LWR OF THE TWO
ASTRO TIDES APPCHG TNGT. WHILE THIS EVNGS TIDES HV REACHED CAUTION
STAGE IN A CPL OF INSTANCES...NO PROBLEMS OBSVD OR XPCTD.

WHILE THE TIDE WL BE HIER TMRW MRNG...WE MAY BE ABLE TO EVACUATE A
BIT OF THE CURRENT SLUG OF WATER. THEREFORE...FORECASTS KEEP ALL
LVLS BELOW MINOR FLOOD THRESHOLDS. WL NEED TO MONITOR CURRENT LVLS
TO ENSURE THAT INDEED IS WHAT HAPPENS.


&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT TUESDAY FOR ANZ533-534-537-
     543.

&&

$$
SYNOPSIS...RCM
NEAR TERM...HTS/SEARS
SHORT TERM...RCM
LONG TERM...IMR
AVIATION...HTS/RCM/IMR
MARINE...HTS/SEARS/RCM/IMR
TIDES/COASTAL FLOODING...HTS


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