Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 010103 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 903 PM EDT TUE SEP 30 2014 .SYNOPSIS... LOW PRESSURE OVER THE GREAT LAKES WILL TRACK EAST ACROSS THE MIDDLE ATLANTIC REGION TONIGHT AND WEDNESDAY. HIGH PRESSURE WILL RETURN TO THE EAST COAST LATER WEDNESDAY AND REMAIN IN PLACE UNTIL A COLD FRONT APPROACHES THE AREA FRIDAY. A COOLER AND DRIER AIRMASS WILL FOLLOW FOR THE WEEKEND AND EARLY NEXT WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... S/WV EJECTING FM H5 LOW SPINNING OVER UPR OHVLY SPREADING SHRA AND A FEW TSRA ACRS CWFA. THE MORE VIGOROUS TSRA/HIER RAFL RATES SEEM TO BE IN SRN PA XTNDG INTO MD. THERE WAS A HAIL THREAT ERLR. DUE TO LWR SUN ANGLE AND SUNSET PRIOR TO 7PM...HVY RA AND WIND GUSTS 15-25 MPH WL MARK THE TOP END OF ACTIVITY. HRRR HAS BEEN DOING A DECENT JOB TRACKING ACTIVITY...ALTHO PRVS CPL RUNS MAY HV BEEN A LTL BIT SLOW. LTST RUN HAS ACCOUNTED FOR THIS...AND TAKES ACTIVITY E OF CWFA BY/SOON AFTER MIDNGT. WL ADJUST DATABASE ACCRDGLY. BIGGER STORY OVERNIGHT MAY BE THE POTENTIAL FOR FOG DEVELOPMENT. PM SHRA/TSRA WL ADD TO THE LOW LEVEL MOISTURE IN PLACE. THE QUESTION IS WHETHER CLDS WL PART ENOUGH FOR RADIATION TO TAKE PLACE. IR SATPIX ACRS WVA CASTS SOME DOUBT ON THAT. WL CONT W/ THE OVERALL CONCEPT OF PATCHY FOG AFTR MIDNGT AND AREAS OF FOG PRE-DAWN. /THERE SHUD BE SOME BINOVC./ HWVR...HV RAISED VSBYS UP A LTL. /ITS A BIAS OF MOST GDNC./ AM NOT AT ALL CONFIDENT ON DENSE FOG ATTM. UPPER LOW WILL PULL AWAY TO THE NORTH AND EAST ON WEDNESDAY. FOG AND LOW CLOUDS WILL MIX OUT BY LATE MORNING/MIDDAY WITH A FEW AFTERNOON SHOWERS POSSIBLE ESPECIALLY OVER THE HIGH TERRAIN. AFTERNOON HIGHS FROM THE LOWER TO MIDDLE 70S CAN BE EXPECTED. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... HIGH PRESSURE TO THE NORTH NOSING INTO THE REGION WILL KEEP AN EASTERLY LOW-LEVEL WIND FETCH IN PLACE WEDNESDAY NIGHT INTO THURSDAY. THIS WILL RESULT IN MORE CLOUDS THAN CLEAR SKY THROUGH THE PERIOD...ESPECIALLY EAST OF THE BLUE RIDGE MOUNTAINS. AS THE HIGH PRESSURE MOVES OUT INTO THE NORTHERN ATLANTIC...MID- AND HIGH-LEVEL CLOUDS APPROACHING FROM THE WEST WILL LOWER AND THICKEN IN ADVANCE OF AN APPROACHING TROUGH THURSDAY NIGHT. A COUPLE OF SHOWERS PRECEDING THIS TROUGH COULD APPROACH THE WESTERN SLOPES BY DAYBREAK FRIDAY...BUT THE BULK OF PRECIPITATION IS EXPECTED TO HOLD OFF UNTIL FRIDAY AFTERNOON AND NIGHT. && .LONG TERM /FRIDAY THROUGH TUESDAY/... A SEASONABLY STRONG UPPER TROUGH AND COLD FRONT WILL MOVE TOWARDS THE MID-ATLANTIC FRIDAY. WIDESPREAD CLOUDS WILL CONTINUE TO LOWER AND THICKEN THROUGH THE DAY...WITH A BAND OF SHOWERS PRECEDING THE FRONT EXPECTING TO MOVE ACROSS THE AREA DURING THE AFTERNOON AND INTO THE OVERNIGHT. MOST AREAS EAST OF THE BLUE RIDGE MOUNTAINS SHOULD REMAIN PREDOMINANTLY DRY DURING THE DAY. MODELS ARE STILL DIVERGENT ON TIMING/STRENGTH OF THE TROUGH WHICH WILL DETERMINE EXACTLY WHO GETS HOW MUCH RAIN AND WHEN. FORCING WITH THE TROUGH IS STRONG BUT THERE IS NOT MUCH INSTABILITY TO WORK WITH...SO WHILE A FEW RUMBLES OF THUNDER CANNOT BE RULED OUT THE CURRENT THINKING IS THAT WIDESPREAD THUNDER IS UNLIKELY. BRIEF HEAVY DOWNPOURS AND PERHAPS GUSTY WINDS IN STRONGER/HEAVIER BANDS OF RAIN COULD BE REALIZED ESPECIALLY IF THE TROUGH ENDS UP BEING ON THE STRONGER SIDE. MODELS ARE IN BETTER AGREEMENT BY LATER SATURDAY AFTER THE FRONT MOVES THROUGH. A MUCH COOLER AND DRIER AIRMASS WILL MOVE INTO THE REGION AND STICK AROUND FOR THE REMAINDER OF THE WEEKEND...WITH TEMPERATURES FALLING TO SEVERAL DEGREES BELOW NORMAL...PERHAPS ISOLATED FREEZING TEMPERATURE READINGS ALONG THE WESTERN RIDGES SATURDAY NIGHT IF WINDS SLACKEN A TAD QUICKER THAN GUIDANCE IS CURRENTLY SUGGESTING. THE NEXT STORM SYSTEM APPROACHES THE AREA FROM THE WEST EARLY NEXT WEEK BUT MODELS ARE HIGHLY DIVERGENT ON WHEN IT AND ITS IMPACTS REACH THE AREA. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... VFR CONDS ACRS ALL TERMINALS ATTM. A LINE OF SHRA/TSRA ALIGNED W/ BLURDG ATTM WL TRACK EWD ACRS HUBS THRU 03Z. STABILITY MARGINAL. SUSPECT ACTIVITY WL WEAKEN FURTHER AS IT APPROACHES. BRIEF FLGT RESTRICTIONS LKLY DURING ITS PASSAGE...MOSTLY MVFR. WL ATTEMPT TO PLACE 1 HR TEMPOS IN TAFS SHORTLY. LOW CIGS AND FOG A GOOD BET OVERNIGHT....MIXING OUT BY LATE MORNING OR MIDDAY WEDNESDAY. WENT A TOUCH MORE OPTIMISTIC THATN PRVS FCST CYCLE...BUT STILL HV SUB-IFR CIGS FOR MRNG PUSH. CIG AND PSBL VSBY RESTRICTIONS LATE WED NIGHT-THU AM AND AGAIN THU NIGHT INTO FRI AM WITH MOIST ONSHORE FLOW PORTRAYED IN ALL THE GUIDANCE. CLIMO IS FAVORABLE FOR FOG/STRATUS THIS TIME OF THE YEAR SO THAT LENDS TO MODERATE CONFIDENCE. SHWRS/ISO TSTMS IN ONE OR MORE BANDS AHEAD OF A COLD FRONT PSBL W/ GUSTY WINDS FRI-FRI NIGHT. VFR SAT AS WINDS TURN OUT OF THE W OR NW. && .MARINE... WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA THE REMAINDER OF TODAY THROUGH THURSDAY. SOLID SCA CONDITIONS LOOKING INCREASINGLY LIKELY LATE THIS WEEK INTO THIS WEEKEND BOTH AHEAD OF /SOUTHERLY FLOW/ AND BEHIND /NORTHWESTERLY FLOW/ A SEASONABLY STRONG COLD FRONT. WINDS/SEAS GRADUALLY ABATE AS THE WEEKEND PROGRESSES. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...KRW NEAR TERM...HTS/KRW SHORT TERM...DFH LONG TERM...DFH AVIATION...HTS/KRW/DFH MARINE...HTS/KRW/DFH

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.