Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 180513 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 113 AM EDT THU SEP 18 2014 .SYNOPSIS... A COOL WEDGE OF HIGH PRESSURE TO OUR NORTH WEAKENS OVERNIGHT INTO THURSDAY. ANOTHER LARGER AREA OF HIGH PRESSURE WILL STRENGTHEN TO THE NORTH OF THE US FRIDAY INTO SATURDAY BEFORE PASSING OFFSHORE ON SUNDAY. A COLD FRONT WILL CROSS THE AREA FROM THE NORTHWEST ON MONDAY BRINGING A BETTER CHANCE OF SHOWERS TO START THE WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 1045 PM EDT WEDNESDAY... SKIES EXPECTED TO CLOUD BACK OVER DURING THE OVERNIGHT. OVERCAST CONDITIONS CURRENTLY EXIST OVER THE FAR WESTERN CWA FROM BLUEFIELD WV TO BOONE NC. THIS AREA OF CLOUD COVER IS EXPECTED TO SPREAD OUT OVERNIGHT AS MOISTURE POOLS UNDERNEATH THE SUBSIDENCE INVERSION VIA THE SHALLOW EASTERLY FLOW. THE EVENING RNK SOUNDING SHOWED INVERSION LAYER BETWEEN 4-7KFT AGL. AMPLITUDE OF UPPER TROUGH DOES NOT CHANGE TOO MUCH HEADING INTO THURSDAY. THINK WE WILL SEE CLOUD COVER EXPAND AGAIN LATER TONIGHT ONCE THE INVERSION SETS UP TRAPPING THE LOW LVL MOISTURE. THERE IS STILL SOME VARIABILITY IN THE CLOUD COVER FORECAST PER MODEL WITH THE NAM HAVING MORE CLOUDS WITH LESS ON THE CMC. GFSMOSGUIDE SEEMS TO BE A TWEENER SO LEANED TOWARD ITS SOLUTION WITH MODIFICATIONS. WITH CLOUDS AROUND THINK THE TEMPS WILL BE AFFECTED SOME...SO LEANED TOWARD MET GUIDANCE NUMBERS OF LOWER 50S MOUNTAINS TO UPPER 50S SOUTHEAST. THE CLUSTER OF SHOWERS AND STORMS ACROSS NRN ARKANSAS/SOUTHERN MISSOURI WILL STAY WELL TO OUR SOUTH. WILL SEE A PIECE OF SHORTWAVE ENERGY MOVE BY THURSDAY WITH SOME CONVERGENCE ALONG THE BLUE RIDGE TO SQUEEZE OUT A FEW SHOWERS. NOT THINKING MORE THAN 20ISH POPS ALONG AND EITHER SIDE OF THE BLUE RIDGE. SKY COVER WILL AGAIN START OUT CLOUDY IN THE MORNING THEN TRANSITION TO PARTLY SUNNY-MOSTLY CLOUDY IN THE AFTERNOON WITH MORE SUNSHINE PUSHING INTO THE MOUNTAINS ONCE THE UPPER WAVE PASSES. JUST A SLIGHT INCREASE IN HEIGHTS WILL LEAD TO HIGHS IN THE UPPER 60S/LOWER 70S MOUNTAINS...TO UPPER 70S OUT ACROSS THE PIEDMONT. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... AS OF 300 PM EDT WEDNESDAY... SHORT WAVE TOPPING WESTERN UPPER RIDGE TRACKS INTO THE SOUTHEAST UNITED STATES...POTENTIAL CLOSING OFF BY LATE FRIDAY. PARTICULARLY STRONG WEDGE BUILDS INTO THE AREA BY FRIDAY MORNING. BUFKIT SOUNDINGS SHOW A SURFACE BASED SATURATED LAYER AS MUCH AS 5000 FEET DEEP TOPPED BY MUCH DRY AIR AND WITH EAST TO SOUTHEAST WINDS FROM LATE THURSDAY NIGHT THROUGH MID AFTERNOON ON FRIDAY. EXPECT WIDESPREAD CLOUDS IN THE WEDGE AND AREAS OF DRIZZLE AND FOG IN THE FAVORED EASTERN UPSLOPE AREAS. STAYED AT OR BELOW COOLER MAV GUIDANCE IN THE WEDGE ON FRIDAY. NEAR THE FRINGES OF THE LOW CLOUDS...IN THE FAR WESTERN COUNTY WARNING AREA...MORE SUNSHINE WILL RESULT IN WARMER TEMPERATURES. SIMILAR PATTERN AGAIN FOR FRIDAY NIGHT...BUT ON SATURDAY FLOW BECOMES SOUTHWEST. EXPECT ENOUGH SUNSHINE BY AFTERNOON FOR WARMER TEMPERATURES ACROSS THE ENTIRE FORECAST AREA. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 300 PM EDT WEDNESDAY... UPPER TROF DIGS OVER THE EASTERN UNITED STATES THROUGH MONDAY NIGHT WITH THE TROF AXIS CROSSING THE COUNTY WARNING AREA ON TUESDAY. MODELS OFFER DIFFERENT SOLUTIONS AFTER TUESDAY. LEANING TOWARD THE ECMWF ENSEMBLE WHICH HAS A BRIEF PERIOD OF NORTHWEST FLOW THEN RISING HEIGHTS ON WEDNESDAY. SURFACE LOW PRESSURE OFF THE SOUTH CAROLINA COAST MOVES NORTHEAST AND WILL BE OFF THE VIRGINIA COAST BY LATE SUNDAY. AT THE SAME TIME...HIGH PRESSURE AND THE WEDGE WEAKENS AS A COLD FRONT APPROACHES FROM THE OHIO VALLEY. MODELS HAVE BEEN CONSISTENT OVER THE PAST FEW RUNS...BRINGING THE COLD FRONT THROUGH THE FORECAST AREA ON MONDAY. A VERY LARGE NEARLY 1030MB HIGH WILL COVER MUCH OF THE UNITED STATES EAST OF THE MISSISSIPPI RIVER TUESDAY AND WEDNESDAY. MONDAY NIGHT AND TUESDAY NIGHT BEHIND THE FRONT...ECMWF HAS 850 MB TEMPERATURES OF +6 TO +8. THIS WILL YIELD TEMPERATURES VERY CLOSE TO NORMAL FOR THE FIRST FEW NIGHTS OF FALL. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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AS OF 1250 AM EDT THURSDAY... PATCHY FOG CURRENTLY STARTING TO TAKE SHAPE ACROSS MOST OF THE REGION WITH SEVERAL TAF SITES ALREADY DOWN TO MVFR. EXPECT THIS TREND TO CONTINUE WHICH SHOULD ALSO SLOWLY LEAD TO LOW CLOUD FORMATION...WITH INITIAL MVFR CIGS OVER THE WEST SPREADING EAST...WHILE LOWERING INTO PATCHY STRATUS BY DAYBREAK ESPCLY VALLEYS AND OUT EAST WHERE SHOULD STAY CLEAR LONGER. THIS BENEATH THE SUBSIDENCE INVERSION THAT MAY ALSO TRAP A CLOUD LAYER IN THE IFR RANGE ALONG THE BLUE RIDGE AROUND DAWN AS WELL SO RUNNING WITH MVFR/IFR MOST SITES OVERNIGHT FOR NOW. AFTER 14Z/10AM...CONDITIONS WILL SLOWLY IMPROVE BACK INTO THE VFR CATEGORY...ANY LOW CIGS LIFTING INTO THE 040-060KFT RANGE FOR THURSDAY AFTERNOON. HOWEVER HEATING MAY PROMOTE SOME BUILDUPS OF CU ACROSS THE MOUNTAINS WHERE ISOLATED AFTERNOON SHRA POSSIBLE BUT IFFY. THUS WONT INCLUDE MENTION AS EXPECT CU FIELDS TO SCATTER OUT BY EVENING UNDERNEATH A LEFTOVER MID DECK SUPPORTING MAINLY VFR INTO EARLY THURSDAY NIGHT. FLOW TURNS MORE EASTERLY LATER THURSDAY NIGHT AS STRONGER HIGH PRESSURE STARTS TO BUILD IN FROM THE NORTH WITH WIDESPREAD MVFR/IFR LIKELY DEVELOPING AFTER MIDNIGHT WITH THE ONSET OF STRONGER WEDGING. EXTENDED AVIATION DISCUSSION... HIGH PRESSURE WILL DOMINATE THE WEATHER THROUGH THE END OF THE WEEK WITH LITTLE OR NO PRECIPITATION. EXPECT MAINLY VFR CONDITIONS OUTSIDE ANY FOG AT NIGHT AND POTENTIAL FOR SOME LOW LEVEL STRATUS ALONG AND EAST OF ROA/BCB...THOUGH THE HIGH PRESSURE SHOULD BE STRONG ENOUGH TO KEEP MOISTURE LIMITED. PRESENCE OF SUBSIDENCE INVERSION ALOFT WILL LIKELY RESULT IN CLOUD LAYER PERSISTING BETWEEN 040-060KFT...SO IT WILL NOT BE ENTIRELY CLEAR. NEXT UPSTREAM TROUGH AND FRONT EXPECTED TO ARRIVE BY EARLY NEXT WEEK WITH A THREAT OF SHOWERS MAINLY LATE SUNDAY NIGHT INTO MONDAY. MAY SEE SOME MVFR CIGS/VSBYS WITHIN A BAND OF SHOWERS DURING THAT PERIOD BUT APPEARS MOST OF THE TIME WILL CONTINUE TO SEE VFR.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...PM/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/PM

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