698 FXUS61 KRLX 060538 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 128 AM EDT MON MAY 6 2013 .SYNOPSIS... LOW PRESSURE CONTINUES TO TRACK SLOWLY EASTWARD ACROSS THE SOUTHEASTERN STATES...BEFORE MOVING UP THE MID ATLANTIC COAST BY MID WEEK. ANOTHER SYSTEM LATE FRIDAY INTO SATURDAY. && .NEAR TERM /THROUGH TODAY/... 1030 PM UPDATE... FORECAST GENERALLY ON TRACK WITH EXPECTED PRECIP CURRENTLY OVER SE OHIO TO ROUGHLY ALONG AND JUST NORTH OF INTERSTATE 64...WITH MUCH OF THE SOUTHERN PART OF THE AREA ESSENTIALLY PRECIP-FREE AT THIS POINT. TWEAKED POPS A BIT TO REFLECT THIS. 730 PM UPDATE... INGESTED DAY/S OBS. NEAR-TERM CONVECTIVE OUTPUT DEPICTING SOME RAIN SHOWERS PUSHING NORTHWARD TO ROUGHLY BTWN CRW AND PKB 00Z TO 03Z...WITH A LULL IN PRECIP COVERAGE/AMOUNTS FURTHER SOUTH ACROSS COALFIELDS/VA COUNTIES. AS SUCH...ADJUSTED POPS TO REFLECT THIS TREND FOR THE NEXT 3 TO 6 HOURS. PREVIOUS DISCUSSION... MODELS CONTINUE TO SHOW SLOW MOVING UPPER LOW PRESSURE SLOWLY MOVE ACROSS THE SOUTHEAST. AS IT DOES...DEFORMATION ZONE RAINS WILL CONTINUE TO OVERSPREAD THE SOUTHERN PORTIONS OF THE CWA. TRIED TO TIME POPS AND THE NORTHERN EXTENT OF RAIN OVERNIGHT. RAINS WILL CONTINUE TO SLOWLY CREEP NORTHWARD DURING THE DAY TOMORROW INCREASING CLOUDS AND POPS. FLOOD THREAT CONTINUES TO MINIMAL AS VEGETATION CONTINUES TO GREEN...SOILS BEGIN DRY AND EXPECTED RAINFALL AMOUNTS GENERALLY RANGING BETWEEN 0.50 TO 1.50 DURING THE LIFE OF THE STORM OVER SOUTHERN PORTION OF THE CWA. GENERALLY KEPT WITH CURRENT THINKING OF TEMPS AND TRIED TO ADJUST FOR CLOUDS AND RAIN. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... UPPER LEVEL SYSTEM WITH WEAK SURFACE REFLECTION CONTINUES TO IMPACT THE AREA THIS PERIOD...ITS IMPACT BEGINNING TO WANE LATE. UPPER LOW CENTER STARTS OUT S-CENTRAL TN OR NORTHERN AL...AND THEN DRIFTS EWD...S OF THE AREA OVERNIGHT...REACHING INTO THE WESTERN CAROLINAS 12Z TUE. FROM THERE...IT LOLLY-GAGS SLOWLY NE AND THEN EVEN N THROUGH THE CAROLINAS...WINDING UP IN N-CENTRAL NC OR S CENTRAL VA BY 00Z THU. THETA E AXIS / ELEVATED WARM SECTOR EXTENDING WWD ACROSS S HALF OF FCST AREA MON EVE WILL CONTINUE THE STEADY RAIN THERE...BEFORE THE AXIS BREAKS DOWN TOWARD TUESDAY MORNING. MODELS HINT THAT AXIS COULD REORGANIZE DURING THE DAY TUE...PUSHING HIGHER POPS W THROUGH CENTRAL PORTION OF FCST AREA DURING THE AFTERNOON. AS THE AGING SYSTEM CONTINUES TO EXPAND AND SLOWLY FILL...PRECIPITATION PATTERN GRADUALLY DEVOLVES INTO SPIRALING BANDS TUE AND ESPECIALLY WED...WHILE THE EXPANDING BUT WARMING COOL POOL ALOFT GIVES RISE TO AN AFTERNOON THUNDERSTORM POSSIBILITY. ON WATER...FFG VALUES ARE LOWEST N...WITH TWO INCHES IN 6 HRS. MODELS GENERALLY CONCUR...WITH THE HELP OF THE SE FLOW SHADOW EFFECT...ON THREE-DAY QPF TOTALS OF 3 TO 5 INCHES MORE OR LESS AROUND THE AREA...TO THE SW...S AND SE...WITH UP TO TWO INCHES IN THE FAR S AND INTO THE MOUNTAINS FROM THE E. WITH THE EXPANSION OF THE SYSTEM...MODELS SUGGEST 1 TO 1.5 INCH AMOUNTS NOW MAKE BETTER IN ROADS INTO CENTRAL PORTIONS OF THE FCST AREA. THESE AMOUNTS OCCUR OVER A 24-36 HR TIME PERIOD AND THEREFORE SHOULD BE NON-IMPACTFUL. POCAHONTAS COUNTY REMAINS IN THE INTERSECTION OF LOWEST FFG AND HIGHEST PRECIPITATION POTENTIAL SO THAT WOULD BE THE FIRST AREA TO WATCH...IF ANY. STILL NO HWO MENTION FOR NOW. BLENDED IN MOSTLY ADJMET AND BIAS CORRECTED ADJMET FOR TEMPERATURES WHICH LED TO NO MAJOR CHANGES. BLENDED IN BIAS CORRECTED MOSGUIDE FOR DAY 3 HIGHS...AGAIN NO MAJOR CHANGE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... NO WHOLESALE CHANGES TO PREVIOUS FORECAST WITH MODELS IN FAIR AGREEMENT WITH EXITING LOW AT BEGINNING OF PERIOD...DIVERGING THEREAFTER. KEEPING THE SLGHT CHC OF POPS AND THUNDER IN DAY 4...MAINLY OH RIVER EAST AS ENOUGH MOISTURE LINGERS WITH DECENT INSTABILITY. GFS AND EC HAVE DEEP TROF PUSHING THROUGH WRN GREAT LAKES DAYS 6 AND 7...DIFFERENCES IN AMPLIFICATION OF THIS TROF LEADS TO DIFFERENT FLOW PATTERNS. DECIDED TO GO NEAR HPC GUIDANCE WHICH FAVORS A BLEND...BUT AM SIDING A LITTLE MORE WITH MORE DETERMINISTIC GFS WITH THIS CYCLE. EITHER SOLN SPELLS DISTURBED WEATHER PATTERN END OF NEXT WEEK. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... A BAND OF RAIN ASSOCIATED WITH AN UPPER LEVEL LOW PRESSURE SYSTEM WILL VERY SLOWLY PUSH NORTHWARD ACROSS THE REGION TODAY AND TONIGHT. A SOUTHEAST WIND FLOW WILL CREATE IFR/MVFR CONDITIONS IN THE SOUTHEAST UPSLOPE AREAS ON THE EAST SIDE OF THE MOUNTAINS. ALONG THE WESTERN SLOPES O THE MOUNTAINS...THIS FLOW WILL KEEP GENERALLY VFR/MVFR CONDITIONS. FURTHER WEST...CONDITIONS COULD DETERIORATE TO IFR IN THE RAIN/SHOWERS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z TUESDAY... FORECAST CONFIDENCE...HIGH INITIALLY...MODERATE TODAY...LOW TONIGHT. ALTERNATE SCENARIOS: WITH THE ATMOSPHERE LOADED WITH MOISTURE...VISIBILITIES AND CEILINGS COULD BE WORSE THAN EXPECTED. 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 MON 05/06/13 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 H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H M M M M M M M M M M M 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 06Z TUESDAY... IFR POSSIBLE IN THE SOUTHEAST UPSLOPE AREAS LATE MONDAY NIGHT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JS/TRM/TAX NEAR TERM...JS/50 SHORT TERM...TRM LONG TERM...TAX AVIATION...RPY