Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 241148 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 748 AM EDT THU JUL 24 2014 .SYNOPSIS... A COLD FRONT WILL ENTER THE REGION TODAY AND SHIFT SOUTHEAST OF THE AREA BY LATE TONIGHT. HIGH PRESSURE OVER THE MIDWEST WILL BUILD ACROSS THE MID ATLANTIC THROUGH FRIDAY. OVER THE WEEKEND THE PATTERN SETS UP FOR POTENTIAL UPPER DISTURBANCES MOVING INTO THE REGION ON A NORTHWEST FLOW. A STRONG FRONT IS EXPECTED TO CROSS THE AREA MONDAY. && .NEAR TERM /THROUGH FRIDAY/... AS OF 730 AM EDT THURSDAY... FORECAST UPDATED TO ACCOUNT MORE COVERAGE IN THE PIEDMONT WITH LESS IN THE WEST. STILL LOOKS LIKE FRONT AND MORE CONVECTION WILL FIRE UP AND MOVE INTO THE WEST LATER THIS MORNING. CLOUD COVER SHOULD HAMPER SEVERITY OF THE STORMS OVER THE MTNS BUT THE POTENTIAL EXISTS FURTHER EAST FOR BREAKS IN THE OVC TO OCCUR TO ALLOW FOR MORE TSRA DEVELOPMENT. PREVIOUS DISCUSSION AT 330 AM... A COUPLE OF SHORTWAVE TO DEAL WITH THROUGH THIS AFTERNOON. FIRST IS OVER THE CENTRAL APPALACHIANS WITH MAIN BATCH OF SHRA AND ISOLATED TSRA OCCURRING ALONG AND AHEAD OF IT. DESPITE INCREASING CIN AND LIMITED INSTABILITY...HIGH THETA-E AND UPPER SUPPORT KEEPING SOME STORMS ACROSS NW NC PIEDMONT INTO SOUTHSIDE VA. 4Z HRRR HANDLED THIS PRETTY WELL...AND FOLLOWED SOME OF THIS INTO THE MORNING. FRONTAL BOUNDARY LIES FROM NORTH OF CRW WEST TO SOUTH OF CVG AND SOUTH TOWARD BNA THIS MORNING. SFC LOW ALONG THE FRONT OVER THE TN VALLEY IS EXPECTED TO PUSH NORTHEAST INTO THE PIEDMONT OF VA BY MID AFTERNOON AND SENDING THE FRONT WELL EAST OF THE MOUNTAINS BY THEN. STILL UPPER SHORTWAVE THAT IS ACROSS IL THIS MORNING IS GOING TO MOVE INTO THE MTNS THIS AFTERNOON AND WILL KEEP THREAT OF SHOWERS/STORMS AROUND. BEST LIFT AND INSTABILITY THOUGH LOOKS TO MOVE EAST OF THE MTNS THIS AFTERNOON. SPC HAS 5 PERCENT FOR DAMAGING WINDS ACROSS MOST OF THE AREA TODAY. SOLAR INSOLATION MAY BE LIMITED AS CLOUD COVER PER SAT TRENDS AND MODEL RH FORECASTS SUGGEST BKN- OVC. THE HIGHS TODAY WILL BE IMPACTED BY BOTH CLOUDS/CONVECTION BUT STILL WARM WITH READINGS RANGING FROM THE MID 70S WEST TO MID 80S EAST. TONIGHT...THE MAIN AXIS OF LIFT AND MOISTURE SHIFTS EAST OF AREA WITH SKIES STARTING TO CLEAR IN THE WEST. WILL KEEP HIGH CHANCE EARLY IN THE EAST THEN DRY IT OUT BY MIDNIGHT/EARLY OVERNIGHT...WHEN MAIN TROUGH AXIS AT 5H SHIFTS ACROSS. LESS HUMID AIR WILL PUSH INTO THE MOUNTAINS AT LEAST THOUGH PROXIMITY OF FRONT THAT STALLS OVER ERN NC/SC MAY INHIBIT THE LOWER DEWPOINTS REACHING THE SE CWA UNTIL FRIDAY. LOWS ARE GOING TO RANGE FROM THE MID 50S ACROSS THE HIGHER MTNS TO MID 60S SOUTHEAST. FRIDAY WILL BE DRY AND LESS HUMID WITH HIGH PRESSURE NOSING IN FROM THE MID ATLANTIC TURNING WINDS AROUND MORE TO THE NE-E. HIGHS RANGING FROM THE UPPER 70S MTNS TO LOWER 80S ROANOKE TO MID 80S EAST CAN BE EXPECTED. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... AS OF 350 AM EDT THURSDAY... FOR SATURDAY...MOISTURE WILL BEGIN TO RETURN TO THE FORECAST AREA FROM THE SOUTH AND SOUTHWEST. CAN`T RULE OUT A LATE AFTERNOON POPUP SHOWER OVER THE MOUNTAINS...BUT THINK MOST AREAS WILL REMAIN DRY UNTIL THE ARRIVAL OF A FRONT MONDAY. WILL HAVE TO MONITOR THIS UPSTREAM FRONT CLOSELY AS IT MAY CAST SOME PREFRONTAL SHOWERS AND STORMS OUR WAY AS EARLY AS SATURDAY NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 515 PM EDT WEDNESDAY... STRONG COLD FRONT IS SLATED TO CROSS THE FORECAST AREA LATE SUNDAY INTO MONDAY...ASSOCIATED WITH A VIGOROUS SHORT WAVE TROUGH THAT WILL BE MOVING ACROSS THE GREAT LAKES AND OHIO VALLEY. THIS PARTICULARLY STRONG DISTURBANCE...NOTED BY ALL THE MODELS...PROMISES TO AMPLIFY THE EASTERN LONG WAVE TROUGH...A PATTERN THAT WILL NET COOLER THAN NORMAL TEMPERATURES FOR SEVERAL DAYS NEXT WEEK. DURING THE TRANSITION SUNDAY INTO MONDAY...INCREASED INSTABILITY AHEAD OF THE FRONT ALONG WITH STRONG DYNAMIC FORCING WILL RESULT IN POTENTIAL FOR STRONG TO SEVERE STORMS. THE OPPORTUNITY WILL EXIST FOR ORGANIZED DEEP CONVECTION WITH POTENTIAL FOR A MESOSCALE CONVECTIVE SYSTEM (MCS) TO CROSS THE FORECAST AREA FROM THE WEST. ATTM WILL MAINTAIN THE BEST CHANCE FOR SHOWERS/STORMS SUNDAY...WITH THE THREAT LINGERING INTO MONDAY UNTIL THE SURFACE FRONT CAN COMPLETELY CLEAR THE FORECAST AREA. GENERALLY FOLLOWED HPC GUIDANCE THROUGH THE PERIOD TRENDING POPS DOWNWARD AFTER THE EARLY WEEK FROPA. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 735 AM EDT THURSDAY... MOISTURE IN THE LOW LVLS PLUS ADDED RAINFALL HAS ALLOWED FOR FOG AT A FEW LOCATIONS THIS MORNING. HOWEVER EXPECT THIS TO BE SHORT LIVED. SHOWERS ARE GOING TO BRING TEMP MVFR VSBYS TO DAN TO START THE TERMINALS. HIGH-RES MODELS FAVOR MORE CONVECTION MOVING OUT OF WV INTO VA AREA BY MIDDAY...WITH BEST CHANCE IN THE ROA/LYH/DAN CORRIDOR. THIS AFTERNOON. KEPT VCTS IN BUT HAVE ENOUGH CONFIDENCE IN THE HIGH RES MODELS OVERALL TO ADD TEMPO THUNDER IN AT LYH/DAN LATER THIS AFTERNOON. LOOK FOR CIGS TO BE MVFR IN THE MTNS EARLY BEFORE BECOMING VFR BY MIDDAY/18Z. CONVECTION WILL EXIT THE MOUNTAINS BY 21-22Z AND DAN/LYH BY 00Z. TONIGHT WILL BE TRICKY AS DRY AIR MAY BE SLOW TO ARRIVE IN EARNEST. DEPENDING ON HOW MUCH RAIN OCCURS AND WITH CLEARING THINK FOG WILL BECOME AN ISSUE AT MOST SITES. THINK LWB/BCB WILL HAVE DENSE FOG AT LEAST BEFORE THE DRY AIR ARRIVES. EXTENDED AVIATION DISCUSSION... AIRMASS WILL DRY OUT BEHIND THE FRONT GOING INTO FRIDAY- SATURDAY. VFR FRI- SAT OUTSIDE OF ANY VALLEY FOG AT KLWB/KBCB EACH MORNING. ANOTHER FRONT AND ASSOCIATED UPPER IMPULSES COULD BRING A GOOD THREAT OF STORMS IN THE SUN-MON TIME FRAME. DURING THIS TIME MAINLY VFR...EXCEPT IN TSRA AND FOR ANY LATE NIGHT FOG. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...PM/WP LONG TERM...PM AVIATION...WP

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