Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 181827 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 227 PM EDT THU SEP 18 2014 .SYNOPSIS...
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HIGH PRESSURE...CENTERED TO OUR NORTH...MOVES OFF NORTHEAST COAST FRIDAY. COLD FRONT AROUND LATE SUNDAY INTO SUNDAY NIGHT..
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&& .NEAR TERM /THROUGH FRIDAY/...
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AREA REMAINS UNDER CONTROL OF HIGH PRESSURE THAT WILL MOVE INTO EASTERN ONTARIO/SOUTHERN QUEBEC TONIGHT. WEATHER MAKER TONIGHT WILL BE THE SURFACE FLOW TURNING SOUTHEASTERLY GIVING UPSLOPE CLOUDS FOR THE EASTERN SLOPES AND A FILLING MID LEVEL TROUGH AXIS. THE MID LEVEL TROUGH SHOULD SLING SOME MOISTURE BACK INTO THE MOUNTAINS AS WELL IN THE FORM OF MID LEVEL CLOUD COVER. EXAMINATION OF THE NAM BUFR SOUNDINGS SHOWS ENOUGH OF A SATURATED LAYER FRIDAY TO WARRANT SLIGHT CHANCE POPS OVER THE SOUTHERN ZONES. NO THUNDER EXPECTED WITH A MID LEVEL CAP IN PLACE LIMITING THE VERTICAL EXTENT. AND WHILE COVERAGE WILL BE SPARSE...NOT EVERYONE WILL REMAIN DRY...ESPECIALLY IN THE SOUTHWEST VIRGINIA AREA. MET GUIDANCE REIGNS SUPREME FOR THE OVERNIGHT LOWS...AND USED THIS AS THE BASELINE FOR THE TEMPERATURE FORECAST TONIGHT. TEMPERATURES TOMORROW WILL BE NUDGED UPWARDS WITH THE FLOW STARTING TO SHIFT TO A SOUTHERLY DIRECTION.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... QUIET PATTERN WILL CONTINUE IN THE SHORT TERM. BROAD UPPER TROUGHING OVER THE NORTHEAST CONUS FRIDAY WILL GRADUALLY BREAK DOWN WITH ZONAL FLOW SATURDAY AS ANOTHER UPPER TROUGH MOVES EASTWARD ACROSS THE UPPER MIDWEST INTO THE GREAT LAKES. NO MAJOR CHANGES FROM PREV FCST WITH LATEST DATA. SFC HIGH PRESSURE CENTERED TO THE NORTH AT THE OUTSET OF THE PERIOD CONTINUES TO SHIFT EASTWARD OFF THE NEW ENGLAND COAST BY 00Z SAT WITH RESULTANT BL WINDS SETTING UP OUT OF THE SOUTHEAST. LLVL MOISTURE WILL BANK UP AGAINST THE EASTERN MOUNTAINS AND HAVE CONTINUED A SLIGHT CHANCE OF SHOWERS IN THAT GENERAL AREA AS SUCH...AGAIN WHICH PREV FCST HAD A GOOD HANDLE ON. LATEST NAM12 MOISTURE PROFILES HINT AT SOME POTENTIAL FOR CONVECTIVE SHOWERS FURTHER WEST OVER THE CENTRAL WV LOWLANDS BUT AT THIS POINT...MOISTURE AVAILABILITY AT AROUND THE 850MB-800MB LEVEL MAY BE SOMEWHAT OVERDONE AS WELL AS THE CO-LOCATED INSTABILITY. THUS FOR NOW...LEFT THE FORECAST DRY FOR ALL OF THE LOWLANDS. MAX TEMPS GENERALLY UPPER 70S LOWLANDS STILL LOOK GOOD. DRY WEATHER UNDER MOSTLY SUNNY/CLEAR TO PARTLY CLOUDY SKIES WILL CONTINUE FRIDAY NIGHT AND SATURDAY WITH LESS LLVL MOISTURE AVAILABLE. ONLY CHANGE OF ANY REAL SIGNIFICANCE WAS TO RAMP UP TEMPS ON SATURDAY BY A GOOD 3-5 DEGREES FOR MUCH OF THE LOWLANDS. TEMPS AT 925MB PROGGED AROUND 20C-22C SHOULD RESULT IN LOW 80S FOR MANY LOCATIONS...A TREND WHICH IS ALSO BEARING OUT IN LATEST MOS GUIDANCE. TEMPS WILL BE SLIGHTLY WARMER SAT NIGHT VERSUS FRI NIGHT WITH SOUTH/SOUTHWEST WINDS AND INCREASING CLOUDS WITH AN APPROACHING COLD FRONT MOVING INTO THE LOWER GREAT LAKES REGION BY 12Z SUN. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... USED WPC THINKING WITH SOME MINOR TWEAKS. COLD FRONT WILL PUSH SOUTHEAST OF THE MOUNTAINS SUNDAY NIGHT WITH HIGH PRESSURE TAKING CONTROL BY MONDAY AFTERNOON. THE HIGH SHOULD BE IN CONTROL THROUGH THE REMAINDER OF THE PERIOD...RESULTING IN DRY AND SEASONABLY COOL TEMPERATURES. WPC TEMPS LOOKED GOOD AND WERE GENERALLY USED. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... EXPECT OVERALL CLEARING THROUGH THE EVENING AS DIURNAL HEATING WANES. AFTER 00Z TONIGHT...THE MOUNTAINS WILL BE UNDER THE INFLUENCE MID LEVEL CLOUDS AND SOUTHEAST FLOW AT THE SURFACE. THIS SHOULD BRING CLOUDS INTO THE EKN AREA AND HALT THE FORMATION OF THE TYGART VALLEY FOG FOR THAT TERMINAL. FURTHER SOUTH AT BKW...SOUTHEAST FLOW BRINGS IFR CEILINGS LATE TONIGHT...LINGERING INTO FRIDAY WITH DRIZZLE POSSIBLE. NAM BUFR SOUNDINGS WERE THE MOST USEFUL TOOL FOR THE BKW TAF...SHOWING THE TIMING OF BOUNDARY LAYER SATURATION AND THICKNESS OF THE SATURATED LAYER RESULTING IN DRIZZLE POTENTIAL FRIDAY. ELSEWHERE IN THE LOWLANDS...EXPECTING A LARGELY TYPICAL LATE SUMMER NOCTURNAL FOG PATTERN. RELIED ON THE LAMP GUIDANCE FOR TIMING OF IFR/LIFR VISIBILITIES. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: NAM MAY BE TOO AGGRESSIVE WITH THE EASTWARD EXTENT OF THE UPSLOPING IFR CEILINGS AT BKW. EKN FOG MAY NOT BEGIN OR ERODE AT FORECAST TIME. 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 M M 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 M L L PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H H AFTER 18Z FRIDAY... IFR CONDITIONS POSSIBLE SUNDAY IN SHOWERS/STORMS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...50/26 NEAR TERM...26 SHORT TERM...50 LONG TERM...JSH AVIATION...26

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