Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 171947 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 347 PM EDT WED SEP 17 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 THURSDAY/... AS OF 300 PM EDT WEDNESDAY... AMPLITUDE OF UPPER TROUGH DOES NOT CHANGE TOO MUCH HEADING INTO THURSDAY. THIS AFTERNOON...SFC ANALYSIS INDICATED A TROUGH OVER THE SOUTHERN APPALACHIANS. MODELS ARE PAINTING ENOUGH THETA-E CONVERGENCE TO ALLOW FOR ISOLATED SHOWERS ACROSS THE MOUNTAINS OF NORTH CAROLINA...NORTHEAST INTO THE SRN VA BLUE RIDGE. MOST AREAS STAY DRY WITH CLOUD COVER VARYING FROM CLOUDY TO PARTLY CLOUDY. THINK WILL SEE CLOUD COVER EXPAND AGAIN LATER THIS EVENING 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 /THURSDAY NIGHT 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 /20Z WEDNESDAY THROUGH MONDAY/... AS OF 125 PM EDT WEDNESDAY... CIGS HAVE BEEN RISING THROUGH THE DAY AND MOST LOCATIONS ARE VFR OR HIGH END MVFR. THINK VFR WILL CARRY US INTO THIS EVENING WHEN THE INVERSION SETS UP AGAIN WITH EAST-SE FLOW ALLOWING FOR SOME STRATUS LAYER TO FORM. QUESTION IS HOW MUCH COVERAGE. MODELS ARE FAVORING SUB VFR AT ALL SITES ALONG WITH FOG...SO MADE THE TAFS SIMILAR TO THE PREVIOUS ISSUANCE AND WENT PESSIMISTIC ON VSBYS AT ALL BUT ROANOKE. WILL SEE SOME RECOVERY BACK TOWARD MVFR/VFR AFTER 12Z...WITH VFR IN THE AFTERNOON THURSDAY AHEAD OF THE NEXT TROUGH. EXTENDED AVIATION DISCUSSION... TROUGH IN THE EAST LIFTS LATE THIS WEEK INTO SATURDAY BUT WEAKNESS ALOFT TO LINGER OVER THE SOUTHEAST. HIGH PRESSURE AT THE SFC WILL WEDGE SOUTHWEST INTO OUR AREA DURING THIS TIME. EXPECT MAINLY VFR CONDITIONS OUTSIDE ANY FOG AT NIGHT AND POTENTIAL FOR SOME STRATUS ALONG AND EAST OF ROA/BCB...THOUGH THE HIGH PRESSURE SHOULD BE STRONG ENOUGH TO KEEP MOISTURE LIMITED. NEXT UPSTREAM TROUGH AND FRONT EXPECTED TO ARRIVE BY EARLY NEXT WEEK WITH A THREAT OF SHOWERS. MAY SEE SOME MVFR CIGS/VSBYS BUT APPEARS MOST OF THE TIME WILL CONTINUE TO SEE VFR. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/WP

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