Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 011742 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 142 PM EDT MON JUN 1 2015 .SYNOPSIS... A COLD FRONT JUST WEST OF THE MOUNTAINS WILL DRIFT EAST INTO THE AREA LATER TODAY BEFORE STALLING ALONG THE BLUE RIDGE OVERNIGHT INTO TUESDAY. LOW PRESSURE RIDING UP ALONG THE BOUNDARY WILL KEEP PERIODIC ROUNDS OF SHOWERS AND STORMS GOING INTO THE MIDDLE OF THE WEEK. THE BOUNDARY WILL SLOWLY DRIFT INTO THE CAROLINAS ON WEDNESDAY AS HIGH PRESSURE BUILDS NORTH OF THE AREA AND WEDGES SOUTH ALONG THE APPALACHIANS INTO THURSDAY OR FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1005 AM EDT MONDAY... GOING TO SEE COVERAGE OF SHOWERS AND THUNDERSTORMS INCREASE OVER THE MTNS AS WE HEAD TOWARD EARLY AFTERNOON AHEAD OF UPPER LOW SITUATED OVER THE TN VLY. MADE SOME ADJUSTMENTS DOWN TO POPS THIS MORNING AS COVERAGE IS SPARSE. MAIN FOCUS FOR CONVECTION WILL BE STRONG LOW LVL CONVERGENCE AND MOISTURE POOLING ACROSS THE MTNS...SO HIGHER POPS SEEM JUSTIFIED HERE. NOT GOING TO ISSUE ANY FLASH FLOOD WATCHES AT THIS TIME AS OVERALL COVERAGE HAS NOT BEEN GREAT IN THE PAST 2 DAYS. WILL HAVE TO WATCH FOR STRONGER STORMS OVER THE MTNS OF FAR SW VA INTO SE WV THOUGH FOR TRAINING AND POSSIBLY ISOLATED FLOODING. PWATS OF 1.0 TO 1.25 INCREASING TO 1.5 TO 1.75 THIS AFTERNOON AND MODIFIED SOUNDINGS INDICATE POTENTIAL FOR WET MICROBURSTS...THOUGH ISOLATED THREAT. NO CHANGES TO FORECAST HIGHS WITH MID 80S EAST TO UPPER 70S WEST. PREVIOUS DISCUSSION FROM EARLY THIS MORNING... INCREASING THREAT FOR MORE PERIODIC ROUNDS OF SHOWERS AND STORMS TO TAKE PLACE OVER THE NEXT 24 HOURS AS THE UPPER TROUGH TO THE WEST SHIFTS EAST PUSHING ITS ASSOCIATED WEAK COLD FRONT INTO THE REGION TONIGHT. AHEAD OF THESE FEATURES...DEEPENING SOUTH/SW FLOW WILL CONTINUE TO PULL HIGH PWAT MOISTURE OF 1.5-2 INCHES NORTH RESULTING IN SHRA/TSRA OVER THE SOUTH/SE EARLY THIS MORNING PER AXIS OF HIGH SURFACE BASED THETA-E...AND THEN ESPCLY WEST/NORTH THIS AFTERNOON/EVENING. HOWEVER MORE CLOUD COVER INTO THE AFTERNOON WILL LIKELY MAKE FOR A BIT LESS INSTABILITY SUGGESTING BIGGER THREAT WITH HEAVY RAIN GIVEN WEAK BUT UNIFORM SW FLOW ALOFT AND POTENTIAL FOR TRAINING BANDS OR CLUSTERS. LATEST GUIDANCE SHOWS BEST LIFT RIGHT AHEAD OF THE FRONT OVER THE FAR WEST BY MID/LATE AFTERNOON...THEN ACROSS THE NORTH AS THE BOUNDARY SAGS IN AND DIFFLUENCE INCREASES OVERTOP LOW LEVEL CONVERGENCE WITH A WEAK SURFACE WAVE ALONG THE FRONT. THUS AFTER EARLY CHANCE POPS MAINLY SOUTH...EXPECT A BIT OF A LULL BEFORE CONVECTION REFIRES BLUE RIDGE AND POINTS WEST THIS AFTERNOON WHERE WILL UP TO HIGH LIKELY OR EVEN LOW END CATEGORICAL POPS INTO THIS EVENING. OTHERWISE WONT HOIST ANY FLOOD HEADLINES GIVEN SPREAD OF HEAVY RAIN OVER THE LAST FEW DAYS BUT MAINTAIN MENTION IN THE HWO ALONG WITH ISOLATED SEVERE PER LATEST MARGINAL THREAT OFF SWODY1. SHOULD BE A BIT COOLER TODAY GIVEN CLOUDS AND MORE WIDESPREAD SHOWERS BUT TRICKY AS A LITTLE MORE SUN COULD CAUSE READINGS TO JUMP INTO THE 80S OUT WEST AND WELL INTO THE 80S BLUE RIDGE EAST GIVEN THE LAGGING FRONT. THEREFORE BUMPED UP READINGS A LITTLE IN THE WEST WHILE LEAVING THE EAST IN THE LOW/MID 80S OVERALL FOR NOW. FRONT WILL STILL BE ACROSS THE FAR WEST TONIGHT BEFORE SPILLING SOUTH INTO THE AREA FROM THE NORTH LATE AS A WAVE ALONG THE BOUNDARY PASSES. LATEST MODELS KEEP THE MAIN FOCUS RIGHT ALONG THE FRONT TO THE NORTH AND WEST WITH CONTINUED HIGH POPS NEEDED THROUGH AT LEAST MIDNIGHT. ALSO MAY PERHAPS SEE ANOTHER BAND OUT EAST THIS EVENING FROM EARLIER WESTERN PREFRONTAL CONVECTION OR POSSIBLE OUTFLOW AS SEEN IN THE SPC WRF SOLUTION AND HINTED AT BY OTHER GUIDANCE SO INCLUDED A RIBBON OF LIKELY POPS SE THIS EVENING AS WELL AS OVER THE NW. INSTABILITY WANES FROM NW TO SE OVERNIGHT BUT MOISTURE REMAINS DEEP SUGGESTING AT LEAST SOME ADDED COVERAGE AROUND AFTER MIDNIGHT ESPCLY GIVEN A WEAKLY DIFFLUENT UPPER PATTERN AHEAD OF THE TN VALLEY 5H LOW AND AIDED BY WEAK CONVERGENCE ALONG THE FRONT. THEREFORE LEAVING IN CHANCE POPS MOST SPOTS DESPITE A SLOW DECREASE IN OVERALL FOCUS IN WAKE OF THE EXITING WAVE AND LOSS OF HEATING. TEMPS MAINLY IN THE 60S BUT LIKELY A LITTLE COOLER WEST WHERE LIKELY WORKED OVER FROM A FEW ROUNDS OF CONVECTION. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... AS OF 245 AM EDT MONDAY MODELS ARE IN BETTER CONSENSUS ON THE TIMING OF A FRONTAL PASSAGE ON TUESDAY AS WELL AS THE PLACEMENT OF THE UPPER LOW ACROSS THE MID SOUTH THROUGH THE PERIOD. THIS SPELLS A CONTINUED TREND TOWARD WETTER AND COOLER CONDITIONS. HIGH PWAT VALUES (GREATER THAN 1.5 INCHES) 1-2 STANDARD DEVIATIONS ABOVE NORMAL REMAIN ENTRENCHED ALONG AND EAST OF THE BLUE RIDGE THROUGH THE PERIOD. MEANWHILE...ALOFT OUR FORECAST AREA FALL UNDER A A REGION OF UPPER DIVERGENCE TO THE NORTHEAST OF THE UPPER LEVEL LOW WITH SPOKES OF ENERGY PINWHEELING AROUND THIS LOW. ONE OF THESE WAVES MOVES THROUGH ON TUESDAY...THIS COMBINED WITH THE SFC BOUNDARY PUSHING SOUTH THROUGH THE AREA AND THETA-E RIDGE IN PLACE SHOULD BRING WIDESPREAD SHOWERS AND STORMS...WITH THE BEST INSTABILITY EXPECTED TO BE SOUTH OF THE LOW LEVEL BOUNDARY COINCIDENT WITH SPC`S MARGINAL OUTLOOK. WITH 850MB BAROCLINIC ZONE AND GOOD OVERRUNNING OF HIGHER THETA-E AIR INTO THE AREA...PUSHED UP POPS TO LIKELY CATEGORY LATE TUESDAY INTO TUESDAY NIGHT. WILL HAVE TO MONITOR THIS TIMEFRAME FOR THE POTENTIAL FOR HEAVY RAIN WHICH WILL CONTINUE TO BE HIGHLIGHTED IN THE HWO. WIDESPREAD CLOUDS AND SHOWERS WITH A FAIRLY DEEP MOIST SOUTHEAST FLOW WILL KEEP TEMPS COOLER THAN GUIDANCE VALUES WEDNESDAY.TRENDED HIGHS DOWN NOT ONLY ON WEDNESDAY...BUT WEDNESDAY NIGHT AND THURSDAY AS WELL...AS A WEDGE OF HIGH PRESSURE REMAINS IN PLACE THROUGH THE REST OF THE SHORT TERM PERIOD. WITH THIS PERSISTENT HIGH PWAT AIR LOCKED IN PLACE...UPPER DIVERGENCE FROM THE SLOW MOVING UPPER LOW...WIDESPREAD CLOUDS AND SHOWERS WILL CONTINUE THROUGH THURSDAY. AS 850MB BAROCLINIC ZONE SLIDES SOUTH LATE WEDNESDAY INTO THURSDAY...AXIS OF HEAVIEST PRECIP MAY ALSO PUSH SOUTH OF THE AREA. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... AS OF 1155 AM EDT SATURDAY... EVEN WITH SOME SPREAD IN THE LONG RANGE GUIDANCE...CONSENSUS IN HAS THE CLOSED LOW IS A FAVORABLE POSITION WEDNESDAY NIGHT THROUGH FRIDAY TO BRING ABUNDANT MOISTURE INTO AT LEAST THE SOUTHERN PART OF THE MID ATLANTIC REGION. LESS CERTAIN HOW MUCH OF A SURFACE REFLECTION THERE WILL BE OF THIS FEATURE. FOR NOW WPC WAS FORECASTING A WEAK LOW OVER THE SOUTHEAST. MODELS SUGGEST IS IT POSSIBLE FOR A SHALLOW SURFACE HIGH TO BE WEDGES IN OVER THE APPALACHIANS THROUGH FRIDAY WITH A COASTAL FRONT HELPING ENHANCE THE WEDGE. OVERALL PATTERN FOR THE FORECAST AREA STAYS WET THROUGH AT LEAST THURSDAY WITH NEAR NORMAL TEMPERATURES. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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AS OF 130 PM EDT MONDAY... EXPECT SCATTERED TO NUMEROUS SHRA/TSRA THIS AFTERNOON INTO THE EVENING...WITH THE BEST COVERAGE FROM BLF-BCB-LYH NORTH. THIS IS THANKS TO MOIST LOW LEVELS AND UPPER LOW MOVING ACROSS THE TN VALLEY. THE THREAT OF STORMS WILL BE ERODING OVERNIGHT WITH SOME LIGHT SHOWERS STILL AROUND. MAIN ISSUE REGARDING LATE TONIGHT THROUGH TUE MORNING WILL BE FOG/LOW CLOUDS. SHOULD SEE MINOR CLEARING. THINKING THE MTNS WILL SEE IFR OR WORSE TOWARD MORNING WITH MVFR TO IFR ELSEWHERE. WITH THE STORMS THIS AFTERNOON THRU THIS EVENING CIGS/VSBYS WILL MAINLY STAY OVER 3KFT AND ABOVE 6SM...BUT AT TIMES WITH HEAVY DOWNPOURS EXPECT 1-3KFT CIGS AND 1-3SM VSBYS. EXTENDED DISCUSSION... EXPECT PERIODS OF SUB-VFR CONDITIONS INTO TUESDAY WITH LOWER CIGS/VSBY REDUCTIONS WITH ANOTHER ROUND OF SHRA/TSRA BY MIDDAY INTO TUESDAY AFTERNOON. MODEL TRENDS IN STALLING THE FRONT NEAR THE REGION DURING MIDWEEK SUGGESTS LESS DRYING...WITH CONTINUED ROUNDS OF SHOWERS AND POSSIBLE STORMS INTO THURSDAY...AND PERHAPS LINGERING MVFR/IFR CONDITIONS AS WELL DUE TO THE COMBINATION OF EASTERLY FLOW AND PERIODS OF SHOWERS. THREAT OF MAINLY AFTERNOON/EVENING SHRA/TSRA TO LINGER INTO SATURDAY WITH POTENTIAL MVFR OR WORSE VSBYS LATE AT NIGHT/EARLY MORNINGS WITH FOG.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS/JH NEAR TERM...JH/WP SHORT TERM...PH LONG TERM...AMS AVIATION...JH/WP

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