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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