Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 270829 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 429 AM EDT SAT SEP 27 2014 .SYNOPSIS... HIGH PRESSURE...BOTH AT THE SURFACE AND ALOFT...WILL DOMINATE THE AREA THROUGH THE WEEKEND. LOW PRESSURE DEVELOPING ALONG THE CENTRAL GULF COAST WILL MOVE NORTHEAST LATE IN THE WEEKEND AND EARLY NEXT WEEK...BRINGING WIDESPREAD RAIN TO THE REGION FOR THE FIRST HALF OF NEXT WEEK. SEASONAL TEMPERATURES ARE EXPECTED TO PREVAIL THROUGH THE FIRST PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 415 AM EDT SATURDAY... BENIGN WEATHER EXPECTED THROUGH THE NEAR TERM AS HIGH PRESSURE... BOTH AT THE SURFACE AND ALOFT...DOMINATES THE AREA THROUGH THE WEEKEND. WITH SURFACE HIGH PRESSURE CENTERED TO THE NORTH OF THE REGION THROUGH THE WEEKEND...NE-E FLOW WILL CONTINUE. HOWEVER...THE DEEPEST MOISTURE HAS BEEN PUSHED INTO FAR SOUTHWEST VA/NORTHWEST NC/EAST TN...AND WILL CONTINUE DRIFTING FURTHER SW TODAY BEFORE STALLING ACROSS THE TN VALLEY. DRY AIR WILL CONTINUE TO ADVECT SOUTHWEST FROM NEW ENGLAND AND THE NORTHERN MID-ATLANTIC STATES. THE ONLY REAL WEATHER CONCERN THROUGH THE NEAR TERM IS PATCHY DENSE FOG THIS MORNING AND THE POSSIBILITY OF SUCH AGAIN SUNDAY MORNING. PESKY LOW CLOUDS PERSIST IN THE FAR SW PART OF THE CWA...WHERE MKJ AND GEV ARE BOTH 1/4SM FG...LIKELY CLOUDS ON THE RIDGE TOPS. THIS IS WHERE THE MOISTURE HAS POOLED/CONVERGED. IN THE LOWER ELEVATIONS IN THESE AREAS...FOG WILL BE LESS OF A PROBLEM BECAUSE OF THE STRATUS DECK. FURTHER NORTH...BATTLE BETWEEN DRIER AIR TRYING TO ADVECT SOUTHWEST FROM THE REGION AND MORE IDEAL RADIATIONAL CONDITIONS...BUT IN A FEW SPOTS THE DECOUPLING WON OUT...E.G. LWB WITH 1/4SM FG. ANY PATCHY DENSE FOG SHOULD DISSIPATE QUICKLY AFT 14Z AND OVERALL IT SHOULD TURN OUT TO BE A SUNNY DAY EAST TO PARTLY SUNNY FAR SOUTHWEST. NOT TOTALLY COMFORTABLE WITH MOSTLY SUNNY IN THE SOUTHWEST PART OF THE CWA. MOS GUIDANCE SIMILAR TO MAX/MIN TEMPS. USED A BLEND BETWEEN THE NAM/GFS/ECMWF FOR TODAYS MAX TEMPS WITH A BIAS TOWARD THE MET MOS. FOR TONIGHTS MIN TEMPS...50/50 MODEL BLEND...WHICH RESULTED IN SLIGHTLY WARMER TEMPS THAN PREVIOUSLY ADVERTISED. 850MB TEMPS ALOFT ARE QUITE WARM...HOVERING AROUND +15C...FOR LATE SEPTEMBER. NOT SURE AIR MASS IS DRY ENOUGH TO ALLOW IDEAL RADIATIONAL COOLING. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 400 AM EDT SATURDAY... HIGH PRESSURE WILL WEDGE DOWN THE APPALACHIANS SUNDAY. A DISTURBANCE WILL DEVELOP ALONG THE GULF SUNDAY AFTERNOON AND WILL TRAVEL NORTHEAST INTO SUNDAY NIGHT...EVENTUALLY OVERRUNNING THE SURFACE WEDGE BRINGING RAIN INTO THE FORECAST AREA. RAIN WILL START IN THE SOUTHWEST PORTIONS OF THE FORECAST AREA AND SPREAD NORTHWARD INTO SUNDAY NIGHT. PLAYED HIGH TEMPERATURES SUNDAY CLOSE TO THE COOLER ADJMAVBC WITH READINGS FROM THE MID 60S IN THE MOUNTAINS TO THE UPPER 70S IN THE PIEDMONT. AS THE TROUGH SWINGS EASTWARD OVER THE OHIO AND TENNESSEE VALLEYS...RAIN WILL ENCOMPASS MOST OF FORECAST AREA SUNDAY NIGHT INTO MONDAY. THE NAM AND ECMWF ARE SIMILAR WITH THE EASTERN ADVANCE OF THE RAIN...WHILE THE GFS IS SLOWER BECAUSE OF THE LESS AMPLIFIED TROUGH. LOW TEMPERATURES SUNDAY NIGHT WILL VARY FROM THE MID 50S IN THE WEST TO THE LOWER 60S IN THE SOUTHEAST. THE QPF FORECAST CAN BE PROBLEMATIC WITH POTENTIAL FOR A CSTAR SCENARIO IF CONVECTION WITH THE LOW TRACKS EAST...LIMITING RAINFALL FROM ADVANCING TO THE NORTH. INCREASED POPS AND SLOWED DOWN THE EXIT OF THE DEER MOISTURE ON MONDAY. EXPANDED THE NORTHERN EXTEND OF LIKELY POPS MONDAY WITH THE RAIN. LOWERED HIGH TEMPERATURES MONDAY WITH RICH CLOUD COVER AND RAIN. HIGHS MONDAY WILL VARY FROM THE UPPER 50S IN THE MOUNTAINS TO THE LOWER 70S IN THE EAST. THE MAIN DISTURBANCE WILL MOVE SLOWLY EAST MONDAY NIGHT INTO TUESDAY. LOW TEMPERATURES MONDAY NIGHT WILL GENERALLY BE IN THE 50S. TAPER OFF POPS FROM WEST TO EAST TUESDAY INTO TUESDAY NIGHT. HOWEVER...LOW CLOUDS AND PATCHES OF DRIZZLE MAY LINGER. USED THE SUPERBLEND FOR HIGHS ON TUESDAY WITH VALUES GENERALLY IN THE UPPER 60S AND LOWER 70S. ALLOWED FOR SOME LIGHT POPS IN THE FAR EAST TUESDAY NIGHT WITH LOW TEMPERATURES FROM THE LOWER 50S IN THE WEST TO AROUND 60 DEGREES IN THE EAST. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 400 AM EDT SATURDAY... SURFACE HIGH PRESSURE OVER THE CANADIAN MARITIMES RIDGING DOWN THE EASTERN SIDE OF THE APPALACHIANS INTO THURSDAY. MOIST EASTERLY FLOW MAY RESULT IN LOW CLOUDS AND DRIZZLE. A COLD FRONT APPROACH FROM THE WEST ON FRIDAY. THIS FRONT SHOULD TRAVEL ACROSS OUR REGION FRIDAY NIGHT INTO SATURDAY. WITH ANOTHER COOL WEDGE OF HIGH PRESSURE OVER THE REGION...TEMPERATURES WILL RUN COOLER THAN NORMAL. THE WARMEST DAY WILL BE FRIDAY AND/OR SATURDAY...AHEAD OF THE FRONT. BEHIND THE FRONT...MUCH COOLER TEMPERATURES EXPECTED FOR THE WEEKEND. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... AS OF 145 AM EDT SATURDAY... IMPROVING AVIATION CONDITIONS EXPECTED AFTER 14Z. OVERNIGHT...HOWEVER...LESS STRATUS THROUGH MUCH OF THE CWA THAN IN RECENT DAYS AND MOIST GROUND WITH LIGHT EAST FLOW HAS PROMOTED DEVELOPMENT OF RADIATIONAL FOG. LWB JUST WENT DOWN TO 1SM BR BKN007 AND WOULD EXPECT VERY QUICKLY FOR THEM TO DROP TO 1/4SM FG VV001 AND REMAIN THAT WAY UNTIL AFTER DAYBREAK. BCB WILL ALSO LIKELY SEE IFR-LIFR FG DEVELOP AFT 08Z...ALTHOUGH CURRENTLY THERE IS A STRATUS DECK EXTENDING NORTHEAST FROM NW NC UP THE BLUE RIDGE TOWARD THE BCB/ROA AREA. THIS MAY BE TRANSIENT ALLOWING FOG DEVELOPMENT LATER ON. MOST OTHER SITES SHOULD SEE AT LEAST MVFR BR DEVELOP OVERNIGHT...BUT IFR-LIFR FG CANNOT BE TOTALLY RULED OUT ANYWHERE GIVEN SYNOPTIC PATTERN. INFLUX OF DRIER AIR FROM THE NORTHEAST SHOULD INHIBIT DEVELOPMENT OF WIDESPREAD DENSE FOG. VFR CONDITIONS EXPECTED ALL SITES AFT 14Z WITH JUST SOME SCT SC/CU THROUGH THE DAY AND SCT CI SPREADING NORTHEAST FROM THE SOUTH CENTRAL STATES. WIND REMAINING NE-ESE THROUGH THE TAF VALID PERIOD AT SPEEDS OF 5-9KTS. WILL NOT INCLUDE ANY MENTION OF GUST TODAY. EXTENDED AVIATION DISCUSSION... ASIDE FOR REPEAT OF RIVER VALLEY FOG SATURDAY NIGHT...MAINLY VFR CONDITIONS EXPECTED SUNDAY. THE NEXT POTENTIAL FOR WIDESPREAD SUB-VFR CONDITIONS WILL COME WITH A DISTURBANCE THAT IS PROGGED TO MOVE OUT OF THE GULF OF MEXICO AND ACROSS THE SOUTHEAST STATES EARLY NEXT WEEK. THIS MAY BRING MVFR CIGS MAINLY ALONG/EAST OF THE BLUE RIDGE AS EARLY AS LATE SUNDAY NIGHT WITH POTENTIAL FOR LOWER CIGS IN RAIN TO CONTINUE INTO MONDAY/MONDAY NIGHT ESPCLY OVER SE SECTIONS. HIGH PRESSURE SHOULD RETURN BEHIND THE DEPARTING LOW PRESSURE SYSTEM BRINGING BACK VFR CONDITIONS FOR THE MIDDLE OF NEXT WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RAB NEAR TERM...AMS/RAB SHORT TERM...KK LONG TERM...KK/RCS AVIATION...RAB

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