Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 211839 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 239 PM EDT THU AUG 21 2014 .SYNOPSIS... A STATIONARY FRONT WILL WAVER ACROSS THE MID ATLANTIC AS RIPPLES OF LOW PRESSURE MOVE ALONG THE BOUNDARY. AN WILL TRAVERSE THE FRONT FRIDAY NIGHT...WHICH WILL PUSH IT SOUTH AS A COLD FRONT. HIGH PRESSURE FROM NEW ENGLAND WILL DOWN DOWN THE EAST COAST THIS WEEKEND. && .NEAR TERM /TONIGHT/... ISOLD TSTMS HV ALREADY DVLPD IN THE WRN PART OF THE FCST AREA IN THE SUMMERTIME AIR MASS. MAIN AREA OF PCPN HAS SPENT THE DAY TRAVERSING ACROSS IN INTO SRN OH ALONG A WARM FNT. THIS WL LKLY MOVE INTO THE WRN SXN OF THE CWA IN THE 4-5 PM TIMEFRAME...MOVG E OF THE MTNS THIS EVE. QUSTN WL BE IF IT CAN HOLD TOGETHER - IT ISN`T TOO IMPRESSIVE ATTM AND HRRR IS EVEN LESS SO AS IT TRIES TO MOVE TOWARDS THE METROS AFTR 00Z. REGARDING SVR THREAT - PULSE SVR WOULD BE WORST CASE SCENARIO. FOG LOOKS TO BE OF LESSER CONCERN TNGT THAN LAST NGT. LOWS IN THE 60S W OF I-95...L70S E. && .SHORT TERM /FRIDAY/... BNDRY RMNG IN THE AREA FRIDAY WL MOST LKLY SERVE AS A FOCUS FOR TSTMS. WL KEEP POPS IN CHC RANGE. AGN SVR THREAT LOOKS LOW - LO LVL WIND FIELD IS WEAK...CAPE IS NOT OVERLY IMPRESSIVE. FFG IS RLTVLY HIGH. HIGHS IN THE MU80S. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... AN UPPER LEVEL VORTICITY MAX WILL DIP THROUGH THE AREA OVERNIGHT FRIDAY...BRINGING ANOTHER BOUT OF ENHANCED RAINFALL. SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND WILL RIDGE DOWN THE EAST COAST AS AN UPPER LEVEL SUBTROPICAL RIDGE BUILDS OVER THE EASTERN US. THE SURFACE RIDGE BUILDING DOWN INTO THE AREA WILL WORK WITH LOW PRESSURE OFF OF THE CAROLINA COAST TO BRING ONSHORE FLOW INTO THE MID-ATLANTIC BEGINNING SATURDAY MORNING. THE PRIMARY EFFECTS OF THE INCOMING MARINE AIRMASS WILL BE SEASONABLY COOL TEMPERATURES AND MOSTLY CLOUDY TO OVERCAST SKIES. EXPECT HIGHS ON SATURDAY...SUNDAY AND MONDAY TO ONLY BE IN THE MID TO UPPER 70S. HIGH PRESSURE WILL MOVE MORE OVERHEAD BY MONDAY NIGHT AND ONSHORE FLOW WILL MOSTLY BE SHUT OFF. LIGHT SOUTHERLY FLOW WILL BEGIN TO FILL INTO THE AREA TUESDAY...LEADING TO AN TREND TOWARD MORE SEASONABLE TEMPERATURES BY THE MIDDLE OF THE WEEK WITH HIGHS NEAR 80 ON TUESDAY AND IN THE MID 80S WEDNESDAY AND THURSDAY. HOWEVER...WITH A RATHER DRY PROFILE CONVECTION IS UNLIKELY TUESDAY OR WEDNESDAY. THE NEXT THREAT FOR STORMS ACROSS THE AREA SHOULD BE THURSDAY AS A COLD FRONT APPROACHES THE AREA. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... VFR CONDS XPCTD OUTSIDE OF ANY TSTMS. FOG MAY DVLP AT IAD/CHO/MRB AFTR MDNGT...BUT NOT XPCTD TO BE AS DENSE AS IT WAS THIS MRNG. TSTMS AGN PSBL FRI AFTN. PERIODS OF LOW CEILINGS ARE POSSIBLE AS AN UPPER LEVEL VORT MAX CROSSES THE AREA FRIDAY NIGHT AND THEN AGAIN OVER THE WEEKEND AND INTO EARLY NEXT WEEK AS A MARINE AIRMASS SETTLES INTO THE AREA. && .MARINE... WINDS XPCTD TO RMN BLO SCA VALUES TNGT/FRI. RW/TRW MAY OCCUR ON THE WATERS THIS EVE AND AGN FRI AFTN. A SMALL CRAFT ADVISORY MAY BE NECESSARY FOR THE WIDEST ZONES OF THE LOWER MARYLAND CHESAPEAKE BAY AND THE LOWER TIDAL POTOMAC SATURDAY AFTERNOON THROUGH SUNDAY NIGHT IN BREEZY EASTERLY FLOW. && .TIDES/COASTAL FLOODING... WATER LVLS ABOUT 3/4 FT ABV ASTRO NORMS. FRI MRNG TIDE WL BE HIGH...BUT AM NOT ANTICIPATING REACHING CRITERIA ATTM. HOWEVER... WE ARE WORKING ON A MARGIN OF INCHES. LATER SHIFTS WL MONITOR THE SITUATION. THERE COULD BE MORE NUISANCE ISSUES THIS WKND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ PRODUCTS...WOODY!/CEB

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