Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 180600 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 200 AM EDT SAT APR 18 2015 .SYNOPSIS...
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WEAK HIGH PRESSURE IN PLACE OVERNIGHT AND SATURDAY. WARM FRONT CROSSES SUNDAY EVENING. COLD FRONT CROSSING MONDAY MAY HERALD A PERIOD OF COOLER WEATHER. ANOTHER COLD FRONT WEDNESDAY OR THURSDAY.
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&& .NEAR TERM /THROUGH TODAY/...
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200 AM UPDATE... FCST ON TRACK. PREV DISCN... DEW POINTS HAVE FALLEN IN SOUTHEAST OHIO. EVEN PKB WENT FROM 53 TO 50 FROM 21Z TO 23Z. HOWEVER...IN WEAK FLOW...STILL THINKING HIGHER DEW POINTS WILL HOLD FROM NEAR CKB ON SW TO CRW. SO WE WILL HAVE PATCHY FOG FORMING...THINKING FIRST IN THE CKB TO EKN CORRIDOR TOWARD MIDNIGHT. ALSO CONCERNED THE CIRRUS OF VARYING THICKNESS MAY DELAY FOG IN THE SOUTH. STILL HARD TO DETERMINE IF LOW STRATUS FORMS IN NE LOW LEVEL FLOW FOR 09Z TO 12Z SATURDAY IN CKB TO CRW TO WILLIAMSON CORRIDOR.
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&& .SHORT TERM /TONIGHT THROUGH MONDAY/... VERY GOOD MODEL AGREEMENT THIS PERIOD...ESPECIALLY IN THE MASS FIELDS. UPPER LOW THAT HAS BEEN HANGING AROUND THE FOUR CORNERS AREA OVER THE SOUTHWEST U.S. WILL BE RAPIDLY KICKED OUT BY A VIGOROUS NORTHERN STREAM SHORT WAVE THAT COMES OVER THE WEST COAST UPPER RIDGE. ASSOCIATED SURFACE LOW WILL DEVELOP OVER THE LOWER MISSISSIPPI VALLEY SATURDAY NIGHT...AND LIFT RAPIDLY NORTHWARD WITH THE LEAD UPPER SYSTEM INTO LAKE MICHIGAN BY MONDAY MORNING. THIS...IN TURN...WILL DRIVE A WELL DEFINED FRONT OF PACIFIC ORIGIN NORTHEAST ACROSS THE AREA SUNDAY. THE COMBINATION OF A WELL DEFINED NEGATIVE TILT TO THE SYSTEM...GOOD LOW LEVEL CONVERGENCE...AND INCREASINGLY MOIST BUT MARGINALLY UNSTABLE AIR...WILL RESULT IN A WIDESPREAD BAND OF SHOWERS WITH PERHAPS AN EMBEDDED THUNDERSTORM SUNDAY...MUCH LIKE A WARM FRONT SCENARIO. WHILE MODERATE SOUTHEAST FLOW AHEAD OF THE FRONT WILL TEND TO CREATE SOME DOWNSLOPING AND A SHADOW AREA IN THE RAIN BAND BETWEEN THE OHIO RIVER AND THE MOUNTAINS...THE UPPER DYNAMICS LOOK TO BE STRONG ENOUGH TO PUT CAT POPS EVERYWHERE IN THIS BAND...BUT SOMEWHAT LOWER QPF IN THE SHADOW ZONE. THIS FAST MOVING FEATURE IS NOT EXPECTED TO BE A FLOODING ISSUE. BEHIND THIS LEAD SYSTEM...A COLD FRONT ACCOMPANYING THE NORTHERN STREAM SHORT WAVE WILL ALSO MOVE RAPIDLY ACROSS THE AREA MONDAY. THIS TIME...ENOUGH INSTABILITY WILL BRING MORE THUNDER WITH THE FRONT AS IT MOVES ACROSS MONDAY. THERE MAY BE A RELATIVE BREAK IN SHOWERS SUNDAY NIGHT IN THE WARM SECTOR...BUT WILL CONTINUE CHANCE POPS. EXPECT A BAND OF CONVECTION WITH THE FRONT MONDAY...SO GOING LIKELY WITH SHOWERS AND THUNDERSTORMS. TOO EARLY TO TELL ABOUT SEVERE THUNDERSTORM POTENTIAL WITH THE FRONT...BUT NO FLOODING ISSUES ARE AGAIN EXPECTED DUE TO ITS PROGRESSIVE NATURE. FOR TEMPERATURES...LOOK FOR NEAR SEASONAL READINGS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... COLD FRONT WILL BE EAST OF THE CWA TO START THE LONG TERM...AND HAVE DECREASING POPS MONDAY NIGHT. SLOW MOVING UPPER LEVEL LOW PASSES TO OUR NORTH THROUGH THE WEEK WITH SEVERAL IMPULSES IN THE WEST TO NORTHWESTERLY FLOW...AND HAVE SOME PERIODS OF CHANCE POPS. MODELS ALSO SHOWING A COLD FRONT WEDNESDAY INTO THURSDAY. WITH SOME TIMING DIFFERENCES...BLENDED IN WPC GUIDANCE. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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SFC DEW POINTS WERE LEFT RATHER HIGH THROUGHOUT MUCH OF THE AREA OWING TO THE LACK OF A DRY PUSH FROM THE N. DRIER AIR DID MANAGE TO FILTER DOWN THE MIDDLE OHIO VALLEY WHILE HIGHER DEW POINTS REMAINED POOLED NEAR THE MOUNTAINS. THUS PKB STARTS OUT 59/50 WHILE CKB BEGINS 55/54 WITH IFR FOG ALREADY. CIRRUS IS ALSO ACTING AGAINST THE FOG BUT WAS THIN ENOUGH TO ALLOW DENSE FOG ON AND OFF AT EKN ALL THE WAY BACK AT 02Z AND MORE PERSISTENT DURING THE PAST HR. TIMED DENSE FOG THROUGH 12Z THERE WHILE ALLOWING IFR FOG CKB THROUGH 11Z. FARTHER S MVFR STRATOCU MAY FORM AND INTERFERE WITH FOG FORMATION BUT LEANED MORE TOWARD THE FOG IDEA. HAVE IFR TIMED 10Z THROUGH 11Z CRW. LEFT IFR OUT ALONG THE OHIO RIVER. VFR DAY SAT ONCE THE FOG BURNS OFF QUICKLY AFTER 12Z AND AFTER SOME MORNING CU MIXES OUT. AFTERNOON CU WILL FORM OVER THE HIGHER TERRAIN. VFR SAT NT WITH SOME INCREASE IN MAINLY HIGH CLOUD. CALM AIR OVERNIGHT EXCEPT A LIGHT FLOW DOWN THE OHIO RIVER. LIGHT N TO NE SFC FLOW SAT MIDDAY AND AFTERNOON WILL BECOME LIGHT E TO NE SAT NT. LIGHT N TO NW FLOW ALOFT WILL BECOME LIGHT NE SAT AND LIGHT SE SAT NT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: LOW TO MEDIUM. ALTERNATE SCENARIOS: FOG AND LOW STRATUS TIMING/COVERAGE/THICKNESS MOSTLY 06Z TO 12Z SATURDAY COULD VARY GREATLY IN WEST VIRGINIA FROM DETERMINISTIC FORECAST. 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. DATE SAT 04/18/15 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY H M M L L L M M H H H H HTS CONSISTENCY H H M M M M H H H H H H BKW CONSISTENCY M H H M M M M M M M M H EKN CONSISTENCY L L L L L L L L H H H H PKB CONSISTENCY H H M M M M M H H H H H CKB CONSISTENCY M M L L L L L M H H H H AFTER 06Z SUNDAY... IFR POSSIBLE IN MOSTLY SHOWERS SUNDAY AFTERNOON INTO SUNDAY NIGHT...AND SHOWERS OR THUNDERSTORMS MONDAY INTO MONDAY EVENING.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JMV/MZ/26 NEAR TERM...KTB/TRM SHORT TERM...JMV LONG TERM...MZ AVIATION...TRM

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