Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 121744 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 144 PM EDT SAT APR 12 2014 .SYNOPSIS...
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A WEAK WARM FRONT WILL LIFT NORTH THROUGH THIS EVENING. SOUTHERLY FLOW THROUGH THE WEEKEND WITH WARM SUMMER LIKE TEMPERATURES. NEXT FRONT MONDAY NIGHT.
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&& .NEAR TERM /THROUGH TONIGHT/...
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SENT AN UPDATE FOR SMALL POPS DUE TO DIURNAL HEATING IN THE WARM SECTOR OF THE WARM FRONT LIFTING NORTH ACROSS CENTRAL CWA. BELIEVE SOME PCPN OUT OF POPCORN CU FIELD COULD MEASURE BUT ACCUMULATIONS WILL BE MORE LIKE A HIT OR MISS AND VERY LIGHT. THE HRRR AND NAM MODELS SHOW SMALL AREAS OF QPF WITH THIS FEATURE MOVING NORTH AND DISSIPATING JUST BEFORE SUNSET. UPDATED DEWPOINTS AS THERE IS A 10 DEGREES GRADIENT ALONG THE WARM FRONT WHICH SLOWLY DRIFTS NORTH THROUGH THIS EVENING. PREVIOUS DISCUSSION BELOW... UPDATED SKIES AS EXPECTED DIURNAL CU DEVELOPING ACROSS THE WESTERN SLOPES AND EASTERN MOUNTAINS THIS AFTERNOON. ALSO...ADJUSTED DEWPOINTS INCREASING TO NOON...BECOMING STEADY OR DECREASING SOME DUE TO MIXING...THEN RECOVERING BY SUNSET. REST OF FORECAST REMAINS REPRESENTATIVE FOR DRY CONDITIONS. PREVIOUS DISCUSSION BELOW... HI RES MODELS PICK UP ON SHORT WAVE CURRENTLY OUT OVER THE MISSISSIPPI VALLEY AND TAKE IT EASTWARD ACROSS THE AREA THIS AFTERNOON. THIS FEATURE SHOULD REMAIN MOSTLY INACTIVE PRECIP WISE...DESPITE WEAK WARM FRONT...DUE LACK OF DEEPER MOISTURE AND INSTABILITY. EXCEPTION MAY BE ON EAST FACING SLOPES OF THE NORTHERN MOUNTAINS THIS AFTERNOON WHERE SOUTHEAST FLOW UPSLOPE FACTOR MAY JUST BE ENOUGH TO TRIGGER A SHOWER. WILL INTRODUCE SLIGHT CHC POPS FOR A SHOWER ON EAST FACING SLOPES OF THE NORTHERN MOUNTAINS. OTHERWISE...OCCASIONAL CLOUDS. PREVIOUS DISCUSSION... A TRANQUIL PERIOD BETWEEN SIGNIFICANT WEATHER SYSTEMS. WEAK HIGH PRESSURE OVERHEAD WILL SLIDE EAST TODAY...ALLOWING A WEAK WARM FRONT TO LIFT NORTH ACROSS THE AREA THIS AFTERNOON. GOOD AGREEMENT AMONG THE MODELS ON THE MASS FIELDS. TRAPPED LOW LEVEL MOISTURE UNDER THIS HIGH HAS ALLOWED FIRST SIGNIFICANT WARM SEASON EARLY MORNING FOG TO FORM IN SOME RIVER VALLEYS...BUT WILL BURN OFF BY MID MORNING WITH HEATING AND MIXING. UNTIL THEN...THERE ARE SOME NOCTURNAL LOW STRATUS SHOWING UP IN THE NORTH AND EAST...WHILE SOME MID CLOUDS LINGER ACROSS THE SOUTH FROM AN UPPER DISTURBANCE PASSING TO OUR SOUTH. SO WHILE IT IS EXPECTED TO REMAIN DRY OVERNIGHT...EARLY MORNING CLOUDS WILL BE AN ISSUE FOR HOW MUCH EARLY MORNING FOG FORMS AND IS MAINTAINED. EXPECT ENOUGH STARS...WITH SOME BREAKS IN THE CLOUDS NORTHEAST AND SOUTH...TO HAVE RIVER AND VALLEY FOG EARLY THIS MORNING...BEFORE BURNING OFF. IN ANY CASE...WITH LACK OF DEEPER MOISTURE AND UPPER SUPPORT FOR WARM FRONT...ONLY SOME CLOUDS ARE EXPECTED WITH THE WARM FRONT TODAY...MAINLY NORTH AND WEST. WILL NOT PLAY ON INSTABILITY WITH LACK OF DEEPER MOISTURE...NOR WEAK SOUTHEAST UPSLOPE FLOW...FOR ANY POPS TODAY. WILL KEEP DRY. AS THE HIGH SHIFTS EAST TODAY AND THE WARM FRONT LIFTS NORTH OF THE AREA THIS AFTERNOON...ENOUGH SUNSHINE AND SOUTHERLY BREEZES WILL ALLOW MAX TEMPERATURES TODAY TO REACH NEAR 80 IN MANY AREAS. MOSTLY CLEAR TONIGHT...BUT SOUTHERLY BREEZES WILL LIKELY RESULT IN LESS FOG FORMATION AND A MILD NIGHT.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY/... NO WHOLESALE CHANGES FOR THE SHORT TERM FORECAST TONIGHT AS MODELS ARE HOLDING TRUE TO THE PATTERN FOR SEVERAL FORECAST RUNS NOW. FIGURE THERE WILL END UP BEING SOME MINOR TIMING ISSUES...BUT THE MAIN FEATURE WILL BE THE COLD FRONT AND ITS ASSOCIATED CONVECTION FOR MONDAY AND MONDAY NIGHT. STILL HAVE TO GIVE A BROAD TIME RANGE FOR THE POPS...ALTHOUGH THE 15Z START TIME OVER THE WESTERN ZONES WITH THE LOW END POPS MAY PROVE TO BE A TAD QUICK. MODELS ARE STILL ON BOARD WITH A LOW PRESSURE CENTER RIDING NORTH ALONG THE FRONT AFTER PASSAGE WHICH WILL KEEP THE PRECIPITATION CHANCES ALIVE INTO EARLY TUESDAY. AHEAD OF THE FRONT...LOW LEVEL JET WILL PEAK IN THE 60-70KT RANGE MONDAY EVENING POSING THE POTENTIAL FOR GUSTY THUNDERSTORMS. IN THE SYNOPTIC PICTURE...500MB HEIGHTS DROP BEHIND THE FRONT WITH HIGH PRESSURE GRADUALLY MOVING IN. EXPECTING A MUCH COOLER DAY ON TUESDAY...AND WILL NEED TO WATCH THE TEMPERATURES IN THE LONG TERM TUESDAY NIGHT WITH THE GROWING SEASON GRADUALLY GET GOING. WILL KEEP AN EYE ON THIS OVER THE NEXT FEW DAYS. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... MODELS IN GENERAL AGREEMENT WITH COLD FRONT OVER THE AREA MONDAY NIGHT...WITH LOW PRESSURE FORMING OVER THE SE STATES AND THEN MOVING UP THE FRONT ON TUESDAY. THERE COULD BE SOME SCT THUNDER WITH THE FRONT MONDAY NIGHT WITH SOME INSTABILITY...BUT NOT GREAT. LOW QUICKLY MOVES UP FRONT AND CONTINUES HIGH POPS OVER THE AREA. THEN MOVES OUT TUESDAY NIGHT. COLD HIGH PRESSURE QUICKLY MOVES IN BEHIND THE SYSTEM AND THE HIGHEST ELEVATIONS COULD SEE A LITTLE SNOW BEFORE SYSTEM EXITS. COLD HIGH PRESSURE IS IN CONTROL FOR THE REST OF THE WEEK WITH A GRADUAL WARMING TREND TOWARDS THE WEEKEND. WENT WITH A CONSENSUS BLEND OF TEMPS THROUGHOUT. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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WARM FRONT...NOTICEABLE IN DEWPOINT FIELDS SLOWLY LIFTS NORTH THROUGH THIS AFTERNOON. IN THE WARM SECTOR..SOUTH OF THE BOUNDARY...A CU FIELD IS BUILDING AS SEEN ON VISIBLE SATELLITE IMAGES. HIGH RESOLUTION MODELS SUGGEST ISOLATED TO SCATTERED SHOWERS ARE POSSIBLE WITH WEAK DIURNAL HEATING CONVECTION. CODED A BKN DECK AROUND 3500 FEET SOUTH OF THE BOUNDARY MAINLY AFFECTING BKW. OVERALL...EXPECT VFR CONDITIONS WITH SOUTHERLY GUSTY WINDS DUE TO DIFFERENTIAL HEATING BETWEEN THE CU FIELD AND VERY FEW AND WEAK OUTFLOW BOUNDARIES OUT OF THE HEAVIER SHOWERS IF ANY. EXPECT LOWER ATMOSPHERE TO DECOUPLE EARLY TONIGHT. HOWEVER...MODELS INCREASE SOUTHWEST FLOW ALOFT. THESE WINDS WILL PROBABLY MIX DOWN TO THE SURFACE MID MORNING SUNDAY. CODED THIS FEATURE IN THE EXPECTED PART OF TAF. HIT AND MISS PCPN PRESENT LOW CONFIDENCE TO INCLUDE SHOWERS IN TAF AT THIS POINT FOR THIS AFTERNOON. WITH WIND INCREASING ALOFT OVERNIGHT...EXPECT LESS FOG FORMATION EXCEPT OVER SHELTERED RIVER VALLEYS IF THEY RECEIVE RAIN THIS AFTERNOON. CONFIDENCE IS LOW PER LAV AND OTHER GUIDANCE. THEREFORE...DID NOT INCLUDE IN TAF EITHER. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: HIGH. ALTERNATE SCENARIOS: OCCURRENCE OF RIVER AND VALLEY FOG OVERNIGHT COULD MATERIALIZE OVER AREAS THAT RECEIVE PCPN THIS AFTERNOON. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 18Z SUNDAY... IFR CONDITIONS EXPECTED LATE MONDAY INTO MONDAY NIGHT UNDER MODERATE RAIN SHOWERS.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...MZ/26 NEAR TERM...ARJ/JMV SHORT TERM...26 LONG TERM...21 AVIATION...ARJ

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