Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 041746 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 146 PM EDT SAT JUL 4 2015 .SYNOPSIS... LOW PRESSURE MOVING OFF THE MIDDLE ATLANTIC COAST WILL PUSH A COLD FRONT THROUGH THE REGION TODAY...BRINGING US ANOTHER ROUND OF SHOWERS WITH A FEW RUMBLES OF THUNDER. THEN...UNSETTLED WEATHER WILL CONTINUE TO AFFECT THE REGION FOR THE NEXT SEVERAL DAYS...KEEPING A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST THROUGH THE FIRST PART OF NEXT WEEK...AS TEMPERATURES BEGIN A GRADUAL WARMING TREND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1200 PM EDT SATURDAY... MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND POPS FOR THIS AFTERNOON. AS OF 925 AM EDT SATURDAY... ADJUSTED POPS WITH LATEST RADAR TRENDS THIS MORNING...THEN MODIFIED TOWARDS HRRR AND HIRESW-ARW FOR LATE MORNING INTO THIS AFTERNOON. MODIFIED TEMPERATURES WITH LATEST OBS AND COOL LATE MORNING READINGS TOWARDS LAV. WITH WEST WINDS CREATING SOME SUNSHINE...TWEAKED CLOUD COVER THIS MORNING INTO THIS AFTERNOON. MORE CHANGES AS DAY PROGRESSES. HAPPY 4TH OF JULY! AS OF 430 AM EDT SATURDAY... ESSENTIALLY THE SAME WEATHER FACTORS TO DEAL WITH AGAIN TODAY AS IMPULSES OF SHORT WAVE ENERGY CONTINUE TO ROTATE THROUGH THE UPPER TROF OVER THE EASTERN US WITH A SURFACE FRONT WAVERING AROUND THROUGH THE AREA. TODAYS ITERATION WILL SEE A SURFACE LOW PULLING OFF THE MIDDLE ATLANTIC COAST WHICH SWINGS THE FRONTAL BOUNDARY BACK THROUGH THE REGION AS A COLD FRONT THIS AFTERNOON. THIS WILL BRING ANOTHER ROUND OF SHOWERS WITH SOME THUNDER TO THE REGION...BUT THE CONTINUED LACK OF INSTABILITY INDICATES NO SEVERE FOR TODAY. SOME AREAS OF THE MOUNTAIN EMPIRE REGION INTO THE GRAYSON HIGHLANDS RECEIVED 1.5 TO 2.5 INCHES OF RAIN YESTERDAY SO THEY ARE VULNERABLE TO HYDRO CONCERNS. HOWEVER...DO NOT EXPECT COVERAGE OF PRECIPITATION TO BE WIDESPREAD AWAY FROM THE FRONT...AND THE FRONT SHOULD HAVE A BIT OF A PUSH TO IT TO KEEP THE PRECIPITATION MOVING. THE LACK OF SIGNIFICANT INSTABILITY TO GENERATE DEEP CONVECTION AND THE FACT THAT THE FRONT DOES NOT LOOK LIKE IT WILL GET HUNG UP OVER OUR AREA SHOULD HELP LIMIT QPF AMOUNTS TODAY AND MITIGATE ANY LARGE SCALE FLOOD THREAT SO DO NOT PLAN TO ISSUE A FLOOD WATCH WITH THIS PACKAGE. AS ALWAYS THIS SITUATION WILL BE MONITORED CLOSELY. THE FRONT LOOKS TO PUSH SOUTH OF THE REGION TONIGHT AND THE BULK OF THE PRECIPITATION SHOULD TAPER OFF BY MIDNIGHT WITH JUST SOME LINGERING ISOLATED SHOWERS FOR THE OVERNIGHT. AFTER A CHILLY AND DAMP FRIDAY...TEMPERATURES TODAY SHOULD BE A FEW DEGREES WARMER AS WINDS BECOME WESTERLY AND WE GET SOME BREAKS IN THE CLOUDS. EXPECT HIGHS TODAY FROM THE LOW/MID 80S EAST OF THE BLUE RIDGE TO LOW/MID 70S WEST. LOWS TONIGHT WILL REMAIN MILD WITH READINGS IN THE UPPER 60S EAST TO LOWER 60S WEST. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 415 AM EDT SATURDAY... MODELS HAVE COME INTO BETTER AGREEMENT WITH RESPECT TO THE DEVELOPMENT OF A WEAK CLOSED UPPER LOW ACROSS THE SOUTHEAST STATES AND ITS SUBSEQUENT NORTHWARD DRIFT INTO THE FIRST PART OF NEXT WEEK. TAIL END OF LONG STANDING EASTERN U.S. TROUGH WILL BECOME CUTOFF ACROSS NORTHERN GA/AL/EASTERN TN FROM THE PARENT UPPER TROUGH...WHICH WILL SHEAR OUT ACROSS NEW ENGLAND AS A SHORT WAVE RIDGE DRIFTS INTO THE OH VALLEY. THE UPPER LOW WILL THEN DRIFT SLOWLY NORTHEAST INTO MON...FINALLY LIFTING NORTH OF THE REGION BY TUESDAY AS THE NEXT UPSTREAM TROUGH DIGS INTO THE GREAT LAKES REGION. AS THE LOW MOVES NORTH FROM GA IT TAKES ON A NEGATIVE TILT...WHICH WILL FURTHER ENHANCE OVERALL WEAK DYNAMICS/LIFT AND CERTAINLY PROLONG THE WET WEATHER PATTERN. ABUNDANT DEEP MOISTURE WILL REMAIN IN PLACE WITH PWATS IN THE 1.75 TO 2.0 INCH RANGE ACROSS MUCH OF THE CWA. EXTENSIVE TO NEAR SOLID CLOUD COVER WILL LIMIT HEATING...SO INSTABILITIES REMAIN MEAGER AND OVERALL DYNAMICS ARE WEAK. MODELS ARE IN GOOD AGREEMENT WITH A LARGE SWATH OF DEEP MOISTURE...ASSOCIATED WITH THE UPPER LOW...TRACKING FROM GA/SC NORTHWARD INTO THE RNK CWA BY SUN AFTERNOON...DRIFTING INTO THE NORTHERN PARTS OF THE CWA MON...THEN FINALLY LIFTING NORTHEAST OF THE CWA BY TUE. THIS WILL REQUIRE CONTINUATION OF LIKELY TO CATEGORICAL POPS SAT-MON ACROSS MUCH OF THE CWA...WITH A LIMITED DIURNAL SWING GIVEN THE UPPER LOW ESSENTIALLY DRIFTING RIGHT ACROSS THE HEART OF THE CWA. THE PATH OF THE UPPER LOW SHOULD FOCUS THE HEAVIEST RAINFALL ACROSS THE WESTERN PART OF THE CWA THROUGH MUCH OF THE PERIOD. WITH 3HR FFG VALUES AVERAGING IN THE 1.5 TO 2.5 INCH RANGE ACROSS MUCH OF THE CWA AND THE RECENT PROLONGED WET SPELL...WE WILL NEED TO WATCH RAINFALL AMOUNTS CAREFULLY INTO EARLY NEXT WEEK. HOWEVER...THE LACK OF ANY ORGANIZED OR STRONG CONVECTION...GIVEN THE MEAGER LAPSE RATES AND LACK OF INSTABILITY/DYNAMICS...SHOULD HOLD HOURLY RAINFALL AMOUNTS IN CHECK. WILL CONTINUE TO HIGHLIGHT THREAT OF LOCALIZED FLOODING IN THE HWO...BUT NO FLOOD/FLASH FLOOD WATCH WARRANTED AT THIS TIME. AS THE UPPER LOW DRIFTS NORTH OF THE AREA TUE...WE SHOULD SEE ENOUGH SUBSIDENCE AND DRYING TO FINALLY REDUCE POPS TO JUST SLIGHT CHANCE TO CHANCE CATEGORY. DIURNAL CONVECTION BECOMES A BETTER BET BY TUE AFTERNOON WITH EXPECTED GREATER INSOLATION THAN WE HAVE SEEN IN QUITE SOME TIME. A NEW FRONTAL SYSTEM WILL BE APPROACHING THE WESTERN AREAS BY LATE DAY...WHICH SHOULD ENHANCE ACTIVITY ACROSS THE WESTERN MOUNTAINS AND LINEAR ORIENTED CONVECTION COULD BE APPROACHING THE WV/SW VA COUNTIES BY EVENING. THE SEVERE WEATHER THREAT SHOULD BE MINIMAL WITH LIMITED THUNDER. SPC CURRENTLY JUST HAS GENERAL THUNDER THROUGH THE PERIOD AT THIS TIME. MAXIMUM TEMPERATURES SHOULD REMAIN BELOW NORMAL THROUGH MON...TRENDING CLOSER TO NORMAL VALUES TUESDAY WITH GREATER INSOLATION. MINIMUM TEMPERATURES WILL REMAIN ABOVE NORMAL WITH HIGH PWATS/DEWPOINTS. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 445 AM EDT SATURDAY... WET WEATHER DESTINED TO CONTINUE. AFTER A VERY BRIEF RESPITE FROM WIDESPREAD PRECIPITATION TUESDAY...A NEW FRONTAL SYSTEM WILL DRIFT INTO THE REGION FROM THE WEST BY WED AND THEN BECOME ELONGATED WEST-EAST ACROSS THE CWA AND STALL. WITH SUBTROPICAL RIDGING TO OUR SOUTH AND WESTERLIES TO OUR NORTH...WE ARE DESTINED ONCE AGAIN TO BE STUCK IN AN ACTIVE BAROCLINIC ZONE WITH NUMEROUS EMBEDDED SHORT WAVES TRACKING FROM THE WESTERN U.S. TO THE EASTERN U.S. SEVERAL WAVES OF SHOWERS AND THUNDERSTORMS APPEAR INEVITABLE...WITH ONE WED AND ANOTHER ONE ON THU. UPPER FLOW ATTEMPTS TO TRANSITION BACK TO NORTHWEST FLOW TOWARD THE WEEKEND AS UPPER RIDING AMPLIFIES ACROSS THE CENTRAL U.S. THIS COULD REDUCE THE POTENTIAL FOR PROLONGED CONVECTION/RAINFALL...BUT WILL NONETHELESS KEEP US IN AN ACTIVE AND UNSETTLED WEATHER PATTERN. THERE WOULD APPEAR TO BE A CONTINUED THREAT OF LOCALLY HEAVY RAINFALL...ESPECIALLY IN LIGHT OF ANTECEDENT VERY MOIST CONDITIONS...AND AT LEAST A MINIMAL THREAT OF STRONG TO SEVERE THUNDERSTORMS DURING THIS PERIOD. WITH ABOVE AVERAGE CLOUD COVER AND MOISTURE LEVELS CONTINUING...EXPECT NEAR TO SLIGHTLY BELOW NORMAL MAX TEMPERATURES AND WELL ABOVE NORMAL MINIMUM TEMPERATURES THROUGH THE PERIOD. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 145 PM EDT SATURDAY... A COLD FRONT WILL SLOWLY MOVE SOUTH TONIGHT AND SUNDAY. THIS WILL RESULT IN POOR FLYING CONDITIONS IN CONVECTION AND LOW CLOUDS. SLOW MOVING UPPER LOW TO THE WEST OF THE REGION WILL SPLIT...WITH PARENT TROUGH SHEARING OUT TO THE NORTHEAST BY SUNDAY...WHILE A WEAK CUTOFF DEVELOPS ALONG THE TAIL OF THE UPPER TROUGH ACROSS THE SOUTHEAST STATES. THIS CUTOFF UPPER LOW WILL DRIFT NORTH INTO THE AREA SUNDAY INTO MONDAY. SCT TO BKN MVFR CLOUDS WILL LOWER TO IFR CONDITION IN CONVECTION THIS AFTERNOON INTO TONIGHT. BAND OF SHOWERS JUST AHEAD OF THE COLD FRONT IS DIMINISHING AS TRAVELING SOUTH. HOWEVER...SCATTERED CONVECTION IS FORMING IN THE UNSTABLE AIR. CAPES AND LIS WERE MOST UNSTABLE EAST OF THE BLUE RIDGE THIS AFTERNOON INTO THIS EVENING. THE TAF SITE WITH THE BEST CHANCE OF A THUNDERSTORM IS DAN. A SHOWER MAY CLIP ANY OF THE TAF LOCATIONS THIS AFTERNOON INTO TONIGHT. OVERNIGHT...THE AFOREMENTIONED CUTOFF UPPER LOW WILL BEGIN TO DEVELOP ACROSS THE SOUTHEAST STATES...BUT ASSOCIATED PRECIPITATION WILL NOT DRIFT BACK INTO THE CWA UNTIL AFT 12 SUN. HOWEVER...EXPECT WIDESPREAD LOW CLOUDS/CIGS AND FOG TO DEVELOP OVERNIGHT WITH WIDESPREAD IFR- LIFR CIGS AND VSBYS. SUTHWEST WINDS AT 5-7KTS THIS AFTERNOON WILL BECOMING LIGHT TO CALM OVERNIGHT...HELPING TO PROMOTE WIDESPREAD FOG/LOW CLOUDS WITH VERY MOIST GROUND IN PLACE. MVFR/IFR CONDITIONS ARE EXPECTED SUNDAY WITH SHOWERS AND THUNDERSTORMS. WINDS WILL BECOME SOUTHEAST AT 5-10KTS SUNDAY. MEDIUM TO HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE PERIOD. EXTENDED AVIATION DISCUSSION... POOR AVIATION CONDITIONS TO CONTINUE INTO NEXT WEEK...BUT WINDOWS OF OPPORTUNITY FOR VFR CONDITIONS INCREASE TUE. UPPER LOW/TROUGH WILL LINGER WEST OF THE VA/NC COASTAL PLAIN INTO THE SOUTHEAST STATES THROUGH THE WEEKEND...THEN BEGIN TO DRIFT INTO NORTHERN VA MON. MEANWHILE...A COLD FRONT WILL APPROACH FROM THE OH VALLEY BY WED. THIS LEAVES A VERY UNSETTLED/WET PATTERN ACROSS THE REGION THROUGH THE PERIOD. EXPECT WIDESPREAD LATE NIGHT/EARLY MORNING LOW CLOUDS/FOG WITH IFR-LIFR CIGS/VSBYS. OVERALL...CONDITIONS SHOULD IMPROVE TO MVFR- VFR OUTSIDE SHRA/TSRA ACTIVITY DURING THE AFTERNOONS. AT THIS POINT...TUESDAY APPEARS TO OFFER THE BEST OPPORTUNITY FOR MORE WIDESPREAD VFR CONDITIONS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK/MBS NEAR TERM...AMS/MBS SHORT TERM...RAB LONG TERM...KK/RAB AVIATION...KK/MBS/RAB

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