Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/05/13


AREA FORECAST DISCUSSION
NWS TUCSON AZ
915 AM MST SAT AUG 3 2013 .SYNOPSIS...SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE INTO NEXT WEEK WITH NEAR NORMAL TEMPERATURES. && .DISCUSSION...THIS MORNINGS KTWC SOUNDING WAS CONSIDERABLY DRIER THAN YESTERDAY AT THIS TIME. FRIDAY MORNINGS SOUNDING HAD A PRECIPITABLE WATER OF 1.81 INCHES...WHILE TODAYS PW VALUE WAS DOWN TO 1.38 INCHES. WITH PW`S LOWER TODAY THAN YESTERDAY EXPECT THE FLOODING THREAT TO BE LESSER TODAY THAN YESTERDAY. THE UNMODIFIED SOUNDING FROM THIS MORNING HAD A LIFTED INDEX OF MINUS 5 AND A CAPE OF AROUND 2000 J/KG. HOWEVER...MODIFYING THE SOUNDING USING T=99;TD=53 YIELDS A LIFTED INDEX OF AROUND MINUS 2 AND A CAPE OF AROUND 200-500 J/KG. WATER VAPOR IMAGERY SHOWS A DISTURBANCE OVER SOUTHERN SONORA MEXICO AND MOVING NORTH NORTHWEST. THE MOST RECENT HRRR SHOWS ACTIVITY DEVELOPING TODAY MAINLY BETWEEN TUCSON AND THE INTERNATIONAL BORDER...AS WELL AS OVER THE TOHONO O`ODHAM NATION AND DRIFTING EAST OF THE TUCSON AREA DURING THE MID TO LATE AFTERNOON HOURS. LOCAL WRF MODEL ALSO SHOWS A SIMILAR SOLUTION...BUT WITH THE ACTIVITY FARTHER EAST THAN THE HRRR. AT ANY RATE...THE LOW END CHANCE CATEGORY POPS FOR TODAY SEEM TO BE ON TRACK...SO NO CHANGES PLANNED AT THIS TIME...BUT WILL MONITOR AND ADJUST THE FORECAST BASED ON SATELLITE AND RADAR TRENDS. OTHERWISE...THE POP FORECAST FOR THE REMAINDER OF TODAY IS IN GOOD SHAPE. AS OF 16Z (9 AM MST)...TEMPERATURES ACROSS THE REGION RANGED FROM THE MID 70S TO THE MID 80S. WILL MAKE SOME ADJUSTMENTS TO THE SHORT TERM HOURLY TEMPERATURE GRIDS TO BETTER REFLECT CURRENT TRENDS. OTHERWISE...THINK THE HIGHS FOR THE AFTERNOON ARE ON TRACK. FOR DETAILS REGARDING THE FORECAST BEYOND TODAY...PLEASE REFER TO THE PREVIOUS DISCUSSION BELOW. && .AVIATION...FEW-SCT CLOUDS AT 12-15K FT AGL...AND SCT CLOUDS AOA 20K FT AGL THRU 03/18Z. AFT 03/18Z...SCT CLOUDS AT 5-9K FT AGL. ISOLD-SCT TSRA DEVELOPING AFT 03/18Z AND CONTINUING THRU 04/05Z. WIND GUSTS TO 45 KTS NEAR ANY TSRA...AS WELL AS LOCAL MVFR/IFR CIGS/VSBYS. OTHERWISE...SURFACE WIND GENERALLY LESS THAN 10 KTS THRU 04/16Z. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...MOISTURE WILL REMAIN IN PLACE ACROSS THE REGION THROUGH NEXT WEEK...RESULTING IN A CHANCE OF MAINLY AFTERNOON AND EVENING SHOWER AND THUNDERSTORM ACTIVITY ACROSS SOUTHEAST ARIZONA. OUTSIDE OF GUSTY THUNDERSTORM OUTFLOWS...WINDS DURING THIS PERIOD ARE EXPECTED TO BE LIGHT...GENERALLY LESS THAN 15 MPH AND DIURNALLY DRIVEN. && .PREVIOUS DISCUSSION...UPPER HIGH CELL REMAINED CENTERED OVER TEXAS THIS MORNING WITH A MOIST SOUTHERLY MID AND UPPER LEVEL FLOW IN PLACE. LATEST MODELS KEEP THE UPPER HIGH CENTERED OVER TEXAS THROUGH MOST OF THE UPCOMING WEEK. WITH VERY LITTLE CHANGE IN THE WEATHER PATTERN...RAIN CHANCES SHOULD REMAIN ABOUT THE SAME THE NEXT FEW DAYS. EVENTUALLY...MEDIUM RANGE MODELS DEEPEN A TROUGH OF LOW PRESSURE ALONG THE WEST COAST WITH THE HIGH SHIFTING FARTHER SOUTHEAST LATE NEXT WEEK. THIS COULD BRING SOME DRIER AIR INTO THE AREA FROM THE WEST RESULTING IN LESS THUNDERSTORM ACTIVITY BY AROUND THURSDAY. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS PUEBLO CO
255 PM MDT SAT AUG 3 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 249 PM MDT SAT AUG 3 2013 ...FLASH FLOODING THREAT FOR THE BURN SCARS AND SEVERE THUNDERSTORM THREAT FOR THE SOUTHEAST PLAINS THROUGH THIS EVENING... RICH LOW LEVEL MOISTURE IN PLACE ACROSS SOUTHEAST PLAINS AS OF EARLY THIS AFTERNOON...WITH SFC DEW POINTS IN THE 60S. THIS IS BEING ADVECTED IN BY LOW LEVEL EASTERLY FLOW. CLOUD COVER HAS HUNG IN LONGER ACROSS THE PLAINS THIS AFTERNOON BUT IS ERODING ON WESTWARD EDGE WHICH SHOULD ERODE CIN FROM WEST TO EAST AS THE AFTERNOON PROGRESSES. MEANWHILE...MONSOON PLUME CONTINUES TO LAY ACROSS THE REGION CAUGHT UP IN SOUTHWEST FLOW AROUND WEST SIDE OF SFC HIGH AND SFC DEW POINT ACROSS THE MOUNTAINS ARE QUITE RESPECTABLE...IN THE 40S WITH SOME LOWER 30S ACROSS INTERIOR VALLEY OF LAKE/CHAFFEE COUNTIES. FOR THE REMAINDER OF THIS AFTERNOON AND EVENING...THUNDERSTORMS OVER THE MOUNTAINS WILL SPREAD EASTWARD ACROSS THE ADJACENT PLAINS WITH MODELS SUGGESTING ONE OR MORE THUNDERSTORM COMPLEXES TAKING SHAPE AROUND 03Z BEFORE DROPPING TO THE SOUTHEAST INTO SOUTHWEST KS AND TX/OK PANHANDLES TOWARDS MORNING. SPC MESO ANALYSIS AS OF 18Z SHOWING 2000+ J/KG OF CAPE. 0-6KM SHEARS WILL BE RUNNING AROUND 30-35 KTS OF DEEP LAYER SHEAR. THUS...MULTICELL STORMS WILL PROBABLY BE THE MAIN STORM THREAT...THOUGH COULD NOT RULE OUT AN ISOLATED SUPERCELL ESPECIALLY WHERE LOW LEVEL EASTERLIES MAXIMIZE. THIS WOULD MOST LIKELY OCCUR ACROSS NORTHERN SECTIONS OF THE FORECAST AREA...PARTICULARLY KIOWA COUNTY. OF POTENTIALLY EQUAL OR GREATER CONCERN WILL BE POTENTIAL FOR FLASH FLOODING ON THE BURN SCARS...PARTICULARLY WALDO AND BLACK FOREST. SOUTHEAST UPSLOPE FLOW COMBINED WITH HEATING...AND WEAK SHORTWAVE ENERGY EMBEDDED IN MONSOON PLUME ALOFT SHOULD TRIGGER THUNDERSTORMS OVER THE PIKES PEAK REGION THROUGH 2 PM...WITH A LINE OF THUNDERSTORMS MOVING OFF TO THE EAST ACROSS THE WALDO AND BLACK FOREST BURN SCARS BETWEEN 3 AND 6 PM. A MYRIAD OF SHORT RANGE HIGH RES MODELS SHOW THIS...THOUGH WITH VARYING TIMING. OF COURSE...HAVE SEEN THIS BEFORE IN THE MODELS AND HAD STORMS MIRACULOUSLY SPARE THE BURN SCARS...BUT DEW POINTS SO HIGH (40S AND 50S) THREAT SHOULD BE FAIRLY HIGH TODAY. FLASH FLOOD WATCH STILL LOOKS ON TRACK. THINK THREAT SHOULD DIMINISH AFTER 8 PM...BUT HRRR OCCASIONALLY SHOWS ANOTHER ROUND MOVING OFF AROUND 04Z SO WILL MAINTAIN THE MIDNIGHT END TIME OF THE WATCH FOR NOW. FREQUENTLY THE HRRR OVERESTIMATES THE INTENSITY OF ANY TRAILING ROUNDS OF CONVECTION. THE WEST FORK BURN SCAR IS ALSO UNDER THE GUN TODAY FOR FLASH FLOODING...THOUGH THREAT DOES NOT LOOK AS HIGH AS YESTERDAY. WITH PRECIP WATERS RUNNING AROUND 150% OF NORMAL ACROSS THE WESTERN PORTIONS OF CO...HEAVY RAIN WILL BE A THREAT WITH ANY THUNDERSTORMS WHICH COULD CAUSE FLASH FLOODING SHOULD IT IMPACT THE WEST FORK BURN SCAR. SO WILL BE MONITORING THIS REGION AS WELL. OVERNIGHT...ACTIVITY SHOULD SHIFT EASTWARD AND EXIT THE AREA WITH STRATUS SPREADING/DEVELOPING ACROSS SOUTHEAST COLORADO OVERNIGHT. SUNDAY WILL BE HUMID AGAIN ACROSS THE SOUTHEAST PLAINS WITH DEW POINTS IN THE 50S AND 60S IN THE MORNING AND MONSOON PLUME STILL OVER THE REGION. MODELS SUGGEST LESS CONVECTION TOMORROW...AND EVEN DRY SFC DEW POINTS ACROSS THE SOUTHEAST MTS A LITTLE IN THE AFTERNOON STILL LOOKING AT CAPES AROUND 1500 J/KG ACROSS THE FAR EAST PLAINS AND WITH MONSOON PLUME STILL OVERHEAD...AT LEAST THE TYPICAL SCATTERED AFTERNOON AND EVENING THUNDERSTORMS. BURN SCARS WILL BE UNDER THE GUN AGAIN AS USUAL...BUT THREAT APPEARS A LITTLE LOWER THAN TODAY...SO WILL NOT HOIST ANY WATCHES AT THIS TIME. LATER SHIFTS CAN GET A LOOK AT THE LATEST RUNS AND REASSESS. OTHERWISE...TEMPERATURES TOMORROW SHOULD SKEW SLIGHTLY WARMER THAN THOSE OF TODAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 249 PM MDT SAT AUG 3 2013 ...SEASONAL MONSOON WILL REMAIN IN PLACE THROUGH NEXT WEEK... MOIST PATTERN WILL CONTINUE. SOUTHWEST MONSOON WILL CONTINUE TO TAKE AIM AT SOUTHERN COLORADO THROUGH MOST OF NEXT WEEK. ADDITIONALLY...A LARGE UPPER TROUGH OVER THE NORTHERN SOUTHERN CANADA AND THE NORTHERN TIER OF THE US...WILL SEND SURFACE BOUNDARIES SOUTH THROUGH THE CENTRAL PLAINS AT TIMES...BACKING THE MOISTURE UP AGAINST THE MOUNTAINS. THIS PATTERN SHOULD KEEP PLENTY OF LOW LEVEL MOISTURE IN PLACE ACROSS THE PLAINS AND EAST SLOPES OF THE MOUNTAINS. ALSO...PERIODS OF ENHANCED UPSLOPE FLOW BEHIND THE BOUNDARIES WILL HELP TO LIFT THE AIR AND SQUEEZE OUT THE PRECIPITATION ON A MORE WIDESPREAD BASIS ACROSS THE AREA. SO...ALL SEEMS IN PLACE FOR A RATHER WET PERIOD ACROSS SOUTHERN COLORADO...WITH PERIODS OF HEAVY RAIN AND FLASH FLOODING POSSIBLE EACH DAY OF NEXT WEEK. SPECIFICS OF THE FORECAST ARE DIFFICULT BUT INDICATIONS ARE THAT WE COULD SEE CONVECTIVE COMPLEXES AFFECTING THE PLAINS MONDAY AND TUESDAY NIGHTS...A MORE WIDESPREAD AREA OF PRECIPITATION WEDNESDAY INTO THURSDAY...AND THEN MORE SCATTERED PRECIPITATION AGAIN FRIDAY INTO SATURDAY. ALL OF THESE DETAILS ARE SUBJECT TO CHANGE. STAY TUNED. LW && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 249 PM MDT SAT AUG 3 2013 THUNDERSTORMS COULD AFFECT ALL THREE TAF SITES THROUGH THIS EVENING WITH KCOS HAVING THE GREATEST RISK. WILL CARRY A TEMPO GROUP FROM 21Z TO 01Z TODAY FOR KCOS AND ADJUST AS NECESSARY BASED ON RADAR TRENDS. KPUB AND KALS ALSO CARRY A THREAT FOR -TSRA BUT WILL MAINTAIN VCTS FOR NOW UNTIL RADAR TRENDS BECOME MORE CLEAR. LOCAL ERRATIC WIND GUSTS TO 40 KTS WILL BE POSSIBLE ALONG WITH MVFR CIGS/VIS WITH TSRA. A SEVERE THUNDERSTORM RISK ALSO LIES ACROSS THE SOUTHEAST PLAINS INCLUDING THE KCOS AND KPUB TAF SITES...BUT RISK AT THIS POINT LOOKS TOO LOW TO MENTION GS OR GUSTS OVER 50 KTS IN THE TAF. THIS TOO WILL BE MONITORED. KALS WILL SEE POTENTIAL FOR -TSRA IN VCNTY AFTER 20Z. LOCALLY HEAVY RAIN WITH MVFR CIGS/VIS WITH THUNDERSTORMS WILL BE A POSSIBILITY THERE AS WELL BUT WITH LESS OF A SEVERE THUNDERSTORM POTENTIAL. EXPECT -TSRA THREAT TO DIMINISH AFTER 02Z WITH KCOS AND KPUB SEEING MVFR TO IFR STRATUS MOVING IN AFTER 06Z. THIS WILL PERSIST UNTIL 15-16Z...FOR KPUB...AND UNTIL AT LEAST 17Z FOR KCOS. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR COZ081-082-084- 085. && $$ SHORT TERM...KT LONG TERM...LW AVIATION...KT
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1049 PM MDT FRI AUG 2 2013 .UPDATE... ISSUED AT 1049 PM MDT FRI AUG 2 2013 CONVECTION CONTINUES ALONG THE ROAN PLATEAU IN RESPONSE TO DISTURBANCE MOVING OVERHEAD. HRRR NOT PICKING THIS UP WELL THOUGH NAM12 HAS NAILED IT. GUIDANCE SUGGESTS THIS SET OF STORMS WILL CONTINUE FOR THE NEXT SEVERAL HOURS. CONVECTION ALSO GETTING GOING AGAIN FOR THE SAN JUANS. RAP40 INDICATING A FAIRLY ROBUST VORT MAX HEADING NORTHWARD FROM NEW MEXICO AND LIKELY THE CULPRIT FOR CONVECTION. WENT AHEAD AND UPPED POPS TO KEEP PRECIP IN THE FORECAST ALL NIGHT AS THIS FEATURE MOVES OVER THE REGION. LOOKS TO BE ANOTHER FAIRLY ACTIVE NIGHT. UPDATE ISSUED AT 935 PM MDT FRI AUG 2 2013 MINOR WAVE IN SOUTHWEST FLOW SPARKING A FEW STORMS ACROSS NORTHEAST UTAH THIS EVENING AND HAVE MADE SOME ADJUSTMENTS TO THE FORECAST TO BOOST POPS IN THIS AREA FOR THE REMAINDER OF THE EVENING. PER SLC REPORTS...STORMS BECOMING MORE EFFICIENT RAIN PRODUCERS WITH SMALL HAIL BECOMING LESS OF A THREAT. FEW CELLS ALSO HANGING ON ACROSS PORTIONS OF HINSDALE AND ARCHULETA COUNTIES IN SOUTHWEST COLORADO WHICH WILL BE DISSIPATING OVER THE NEXT FEW HOURS. GRIDS HAVE BEEN UPDATED AND NEW ZONES WILL BE OUT SHORTLY. && .SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT) 306 PM MDT FRI AUG 2 2013 00Z H5 HAND ANALYSIS CONTINUES TO SHOW A BLOCKY NORTHERN STREAM IN THE VICINITY OF THE US/CANADIAN INTERFACE. IN THE EAST TROUGHING IN THE NORTHEAST CONUS IS PHASED MERIDIONALLY BACK INTO THE ARCTIC LATITUDES. THIS FEATURE IS BLOCKING A SMALLER BUT PERSISTENT POSITIVELY TILTED TROF OVER THE NORTHWEST CONUS. BOTH WILL PLAY A ROLE IN THE WEATHER PATTERN BUT THE WESTERN SYSTEM INTERACTION WITH THE SUB TROPICAL HIGH OVER THE SOUTHERN PLAINS WILL BE MORE A DRIVER TO OUR CWA. GOES DERIVED AND SURFACE BASED PWAT DATA INDICATE AROUND AN INCH OF PWAT NEAR GJT THIS AFTERNOON WITH THE MUCH DRIER CONDITIONS TO THE NORTHWEST AND MOISTURE SURGING FROM THE SOUTH. AN AREA OF FASTER WINDS ALOFT ARE STILL BISECTING OUR CWA FROM SW TO NE AND APPEAR TO BE POSSIBLE DRIVER TO THE CONVECTION OVER THE NEXT 24 TO 36 HOURS. STORMS HAVE BEEN SLOW TO FIRE THIS AFTERNOON WITH MUCH BETTER ORGANIZATION OVER SOUTHEAST ARIZONA THIS AFTERNOON. WE SHOULD CONTINUE TO SEE STORMS FORMING OVER OUR SOUTHERN CWA TERRAIN THROUGH THE AFTERNOON...EVENTUALLY FORCING SOME ISOLATED CONVECTION INTO SURROUNDING VALLEYS. OTHER STORMS MAY ALSO DRIFT OUT THE RED STONE AREAS OF ARIZONA AND UTAH INTO OUR SOUTHEAST CWA PRIOR TO SUNSET. EXPECT A DIURNAL DOWNTURN TONIGHT BUT MODELS HAVE BEEN HINTING AT SOME STORMS LINGERING IN THE WEST ALONG WHERE MOISTURE ADVECTION UNDERNEATH A SPEED MAX ALOFT COULD KEEP A FEW ISOLATED STORMS POPPING. NOT CONFIDENT SO POPS REMAIN ISOLATED. ENERGY WILL BE RELEASING FROM PACIFIC NORTHWEST TROF LATE TONIGHT AND TRANSVERSING THE RIDGE ON SATURDAY. THIS WILL SLIGHT SHIFT THE STRONGER WINDS ALOFT EASTWARD WITH SOME DRIER AIR IN THE GREAT BASIN MOVING BACK INTO OUR EASTERN CWA. THE MOISTURE SEEM POINTED INTO THE COLORADO MOUNTAINS WITH ADDITIONAL FORCING COMING FROM THE WAVE OF SOUTHERN ARIZONA TODAY. MODELS TO SEEM TO HAVE TO DEGREE OF FEEDBACK AS WELL SO THINKING THE MORNING SHOULD AGAIN BE FAIRLY QUIET AND ADJUSTED POPS TO INCREASE SIGNIFICANTLY IN THE TYPICALLY DIURNAL FASHION. AT TM THERE IS LITTLE FOCUS FOR THUNDERSTORMS OVERNIGHT SO WILL KEEP THE TREND OF DECREASING STORMS GOING SATURDAY NIGHT. TEMPERATURES WILL REMAIN SEASONAL FOR THE AFTERNOON WITH MILDER NIGHTS WITH THE INFLUX OF MOISTURE. .LONG TERM...(SUNDAY THROUGH FRIDAY) 306 PM MDT FRI AUG 2 2013 THESE PERIODS BEGIN WITH THE PERSISTENT SUBTROPICAL RIDGE CENTERED IN TEXAS AND A DEEPENING TROUGH ALONG THE WEST COAST. EARLY NEXT WEEK...THE INTERACTION OF THE TWO LARGE SCALE FEATURES AMPLIFIES THE RIDGE AXIS TO THE NW INTO NE OREGON. BY EARLY WEDNESDAY THE WEST COAST TROUGH COMES ONSHORE AND DEFORMS THE EASTWARD. THE RIDGE PUSHES BACK A BIT LATE NEXT WEEK. YET NONE OF THIS FULLY EXPLAINS THE SENSIBLE WEATHER IN STORE FOR THIS FORECAST AREA. IT IS THE EBB AND FLOW OF MOISTURE FROM THE S-SW...AND SUBTLE DISTURBANCES THAT ARE THE DRIVERS FOR EARLY AUGUST WEATHER HERE. SUNDAY...MOISTURE IS SOMEWHAT DIMINISHED WITH PRECIPITABLE WATER VALUES NEAR ONE INCH IN THE SOUTH DECREASING TO NEAR HALF AN INCH NORTH. MODELS HAVE HAD GOOD CONSISTENCY FAVORING THE COLORADO SPINE WITH SCATTERED CONVECTIVE STORMS SUNDAY...WITH LESSER COVERAGE IN EASTERN UTAH AND FAR WESTERN COLORADO. EXPECT NEAR NORMAL WARM TEMPERATURES. MODELS HAVE ALSO SHOWN GOOD CONTINUITY WITH A DISTURBANCE AND RESULTING MOISTURE SURGE WORKING INTO THE FOUR CORNERS EARLY MONDAY AND INTO THE NORTHERN ZONES LATE MONDAY OR TUESDAY. INCREASED THUNDERSTORM ACTIVITY EXPECTED FOR ALL ZONES MONDAY- TUESDAY WITH THE POTENTIAL FOR HEAVY SHOWERS FAVORING THE SOUTH WHERE MOISTURE IS DEEPEST AND STORM MOTION IS SLOWEST. WEDNESDAY-THURSDAY THE APPROACHING TROUGH ADVECTS IN SOME DRY AIR AGAIN LIMITING CONVECTION. THE GFS LOWERS PRECIPITABLE WATER VALUES TO 0.4-0.5 INCH FOR THE ENTIRE FORECAST AREA...THOUGH THE DRIEST AIR WILL LIKELY BE IN THE WESTERN HALF. STARTING FRIDAY THERE IS SOME HINT IN BOTH THE EC AND GFS THAT THE MONSOONAL MOISTURE TRIES TO RETURN AT LEAST INTO THE SOUTHERN ZONES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 935 PM MDT FRI AUG 2 2013 ISOLATED THUNDERSTORMS PASSING ACROSS NORTHEAST UTAH MAY IMPACT KVEL UNTIL 08Z THIS MORNING...OTHERWISE VFR CONDITIONS EXPECTED AT ALL TERMINAL SITES THROUGH 18Z SATURDAY. ANOTHER PUSH OF MOISTURE WILL WORK THROUGH THE REGION AFTER 18Z...SPARKING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...MAINLY CONFINED TO THE HIGHER TERRAIN. GUSTY WINDS...BRIEF HEAVY RAINFALL AND SMALL HAIL WILL BE POSSIBLE WITH CONVECTION SATURDAY AFTERNOON AND EVENING. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...TGR SHORT TERM...15 LONG TERM...JOE AVIATION...JDC
AREA FORECAST DISCUSSION
NWS MIAMI FL
812 PM EDT SUN AUG 4 2013 .UPDATE... SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DIMINISH ACROSS THE REGION DURING THE EVENING HOURS. A MID LEVEL TROUGH WILL REMAIN IN PLACE THROUGH THE REST OF TONIGHT AND INTO MONDAY. THIS WILL ALLOW FOR THE LIGHT WEST TO SOUTHWEST STEERING FLOW TO CONTINUE DURING THIS TIME PERIOD. THIS WILL ALSO FOCUS THE BEST CHANCE FOR SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS INTERIOR AND EAST COAST SECTIONS DURING THE AFTERNOON HOURS ON MONDAY. ON TUESDAY THE TROUGH WILL START TO LIFT OUT OF THE REGION AND A RIDGE WILL BEGIN TO BUILD BACK IN. THUNDERSTORM DEVELOPMENT ON TUESDAY WILL OCCUR DURING THE AFTERNOON HOURS ALONG THE EAST AND WEST COAST SEABREEZES AS THEY PROPAGATE INLAND. .AVIATION... CONVECTION CONTINUES TO FIRE ALONG A WEAK SURFACE TROUGH EARLY THIS EVENING STRETCHING JUST EAST OF KTMB AND KMIA NORTHEAST ACROSS THE ATLANTIC WATERS. THIS LINE CONTINUES TO PUSH EAST-SOUTHEAST AND SHOULD STAY EAST OF THE MIAMI-DADE TERMINALS. LATEST HRRR WEAKENS THIS ACTIVITY OVER THE NEXT FEW HOURS. OTHERWISE...LIGHT WINDS AND VFR CONDITIONS ARE EXPECTED OVERNIGHT WITH LIGHT WEST-SOUTHWESTERLY FLOW PREVAILING ON MONDAY. SHOULD SEE A WEAK SEA BREEZE DEVELOP ALONG KFLL AND KFXE BY 17Z MONDAY. && .PREV DISCUSSION... /ISSUED 200 PM EDT SUN AUG 4 2013/ SHORT TERM (TONIGHT-TUESDAY NIGHT)... A LARGE SCALE MID LEVEL TROUGH WILL ACROSS THE EASTERN SEABOARD AND INTO THE ATLANTIC THROUGH MONDAY WITH A STRONG RIDGE AXIS EXTENDING FROM TEXAS TO THE FLORIDA STRAITS. THIS PATTERN WILL ALSO MAINTAIN A SURFACE HIGH PRESSURE RIDGE OVER THE FLORIDA STRAITS. FORECAST SOUNDINGS ALSO CONTINUE TO INDICATE PWAT WILL REMAIN AT AROUND TWO INCHES WITH A WNW STEERING FLOW SO THE HIGHEST CHANCES FOR CONVECTIVE DEVELOPMENT FOR THIS AFTERNOON AND AGAIN ON MONDAY AFTERNOON WILL CONTINUE TO BE OVER THE INTERIOR AND EAST COAST METRO AREAS. THIS IS REFLECTED WELL IN THE CURRENT FORECAST SO NO CHANGES ARE FORESEEN AT THIS TIME. STABILITY WILL ALSO REMAIN UNCHANGED WITH THE LOWEST LEVELS VERY UNSTABLE AND ONLY MARGINAL MID LEVEL LAPSE RATES SO THE PRIMARY CONCERN WILL BE LOCALLY HEAVY RAINFALL AND ISOLATED STRONG WIND GUSTS ALONG WITH THE POSSIBLE FREQUENT LIGHTNING STRIKES. TUESDAY IS CONTINUING TO LOOK LIKE A TRANSITIONAL DAY WITH THE TROUGH LIFTING TO THE EAST WHICH WILL ALLOW FOR A DEEP LAYER RIDGE TO BEGIN DEVELOPING ACROSS THE FLORIDA PENINSULA. THIS RIDGE WILL FIRST SET UP ACROSS SOUTH FLORIDA SO SEA BREEZE INTERACTIONS WILL LIKELY PLAY THE MAJOR FOCUS ON TUESDAY AFTERNOON WITH FORECAST SOUNDINGS SHOWING AN AVERAGE STORM MOTION OF LESS THAN 5 MPH. SO SLOW AND ERRATIC MOVEMENT APPEARS LIKELY WITH EQUAL CHANCES JUST ABOUT ANYWHERE. THE PWAT WILL ALSO CONTINUE AT AROUND TWO INCHES SO THE HEAVIER RAIN THREAT COULD ACTUALLY BE A LITTLE HIGHER WITH THE SLOWER STORM MOTIONS EXPECTED. IN ADDITION, MID LEVEL LAPSE RATES ARE EXPECTED TO REMAIN MARGINAL SO THE ONLY OTHER THREAT WILL BE ISOLATED STRONG WIND GUSTS. LONG TERM (WEDNESDAY-SUNDAY)... GLOBAL MODELS AGREE THAT THE DEEP LAYER RIDGE WILL SHIFT TO NORTH FLORIDA BY WEDNESDAY ALONG WITH A MID LEVEL INVERTED TROUGH MOVING WEST ACROSS THE BAHAMAS. THIS WILL PLACE SOUTH FLORIDA ON THE SUBSIDENCE SIDE OF THIS TROUGH AND THE RAIN CHANCES COULD GO DOWN ALONG WITH A DEEP EASTERLY FLOW SETTING UP. BOTH THE GFS AND ECMWF DEPICT THIS TROUGH MOVING ACROSS SOUTH FLORIDA ON FRIDAY AND INTO THE GULF OF MEXICO ON SATURDAY. THIS COULD INCREASE THE RAIN CHANCES AGAIN WITH INCREASED LAPSE RATES AS THE MID LEVELS COOL ALONG WITH A TRANSPORT OF TROPICAL MOISTURE NORTHWARD FROM THE CARIBBEAN. AVIATION... THE EAST COAST SEA BREEZE HAS BEGUN TO PENETRATE JUST INLAND FROM THE COAST THIS AFTERNOON...WHICH SHOULD ENHANCE THE LOW-LEVEL CONVERGENCE WITH THE LIGHT WESTERLY LOW-LEVEL FLOW IN PLACE. WILL INCLUDE VCTS IN THE EAST COAST TAF SITES FROM 20Z ON TODAY. THE LATEST HI-RES MODEL GUIDANCE CONTINUES TO INDICATE WIDESPREAD ACTIVITY DEVELOPING THROUGH THE LATE AFTERNOON AND EVENING HOURS FAVORING THE EASTERN HALF OF THE SRN FL PENINSULA TODAY. SUB IFR CONDITIONS MAY RESULT FOR PERIODS OF TIME IF THIS ACTIVITY SETS UP OVER THE TERMINALS. WILL INDICATE THINGS TRENDING DOWN BEYOND 02Z WITH ANOTHER QUIET OVERNIGHT EXPECTED. SIMILAR CONDITIONS WILL BE EXPECTED MONDAY WITH THE LIGHT WESTERLY FLOW IN PLACE. MARINE... TRANQUIL WIND AND SEAS WILL CONTINUE THROUGH EARLY THIS WEEK WITH A LIGHT WIND FLOW LESS THAN 10 KNOTS. AN EAST WIND WILL RETURN BY MID WEEK BUT AT SPEEDS OF LESS THAN 15 KNOTS SO OVERALL SEAS ARE EXPECTED TO REMAIN BELOW 4 FEET BUT COULD BE HIGHER NEAR SCATTERED SHOWERS AND THUNDERSTORMS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 75 92 78 91 / 20 50 20 40 FORT LAUDERDALE 77 91 78 88 / 20 50 20 40 MIAMI 78 91 78 91 / 20 50 20 40 NAPLES 77 91 77 90 / 10 40 20 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...55/CWC AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS MIAMI FL
959 AM EDT SAT AUG 3 2013 .UPDATE... MADE SOME EARLIER MINOR ADJUSTMENTS BASED ON CURRENT TRENDS, BUT CURRENT THINKING HAS NOT CHANGED WITH CONVECTION STILL EXPECTED BY THIS AFTERNOON. ALREADY HAVE HAD SOME ISOLATED THUNDER MOVE ONTO THE SOUTHWEST COAST WITH THE 12Z MFL SOUNDING INDICATING A SOUTHWEST STEERING FLOW WHICH CAME BE NO SURPRISE WITH FORECAST SOUNDING HAVING SHOWN THAT ALSO. AS WAS THE CASE YESTERDAY, THE ONLY FLY IN THE OINTMENT MIGHT BE CONVECTIVE DEBRIS FIELD WORKING ITS WAY ONTO THE SOUTHEAST COASTAL REGION THIS MORNING WHICH MAY LEAD TO LIMITED CONVECTIVE DEVELOPMENT. THE HRRR HAS NOT DEPICTED WELL THE STORMS MOVING INTO MAINLAND MONROE COUNTY, BUT OVERALL ITS ANALYSIS OVER THE ATLANTIC HAS BEEN GOOD. IT SHOWS SHOWERS BEGINNING TO FORM AFTER 16Z ACROSS MOST OF THE SOUTH FLORIDA AND THEN EXPANDING THROUGH THE AFTERNOON. GIVEN THE INSTABILITY DEPICTED FROM THE MORNING ATMOSPHERE PROFILE, THIS APPEARS AS REASONABLE WITH THE LOW LEVELS AFTER WARMING SURFACE TEMPERATURES BECOMING VERY UNSTABLE. THE MID LEVEL LAPSE RATES ARE STILL NOT IMPRESSIVE SO THE MAIN THREAT WILL CONTINUE TO BE LOCALLY HEAVY RAIN BUT ISOLATED STRONG WIND GUSTS AND EVEN A WATERSPOUT WILL BE POSSIBLE FROM THE STRONGER STORMS THAT COULD MATERIALIZE. KOB && .PREV DISCUSSION... /ISSUED 736 AM EDT SAT AUG 3 2013/ AVIATION... SCATTERED SHRA/TSRA ARE EXPECTED TO DEVELOP ACROSS SOUTH FL TODAY. PLACED VCTS ALL TERMINALS FOR THE AFTERNOON WHEN TSTORMS WILL BE MOST PREVALENT. IFR IS POSSIBLE AT ANY GIVEN TERMINAL, BUT IT WOULD BE BRIEF AND CONFIDENCE IS TOO LOW TO PLACE ANYTHING MORE THAN VCTS AT THIS TIME. LIGHT-CALM WINDS THIS MORNING ARE FORECAST TO BECOMING S-SE EAST COAST (EXCEPT LIKELY REMAINING SW AT KTMB) AND SW AT KAPF AT 5-10 KT, THEN CALM TONIGHT. /DG PREV DISCUSSION... /ISSUED 351 AM EDT SAT AUG 3 2013/ DISCUSSION... SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WERE ALREADY DEVELOPING EARLY THIS MORNING ACROSS THE ATLANTIC AND GULF WATERS...WITH A FEW SHOWERS AND STORMS ALSO DEVELOPING OVER LAND. THE REMNANTS OF DORIAN WERE LOCATED EAST OF MELBOURNE THIS MORNING...AND THE SYSTEM WAS SHOWING SIGNS OF REDEVELOPING. MODEL GUIDANCE IS INDICATING THAT THE TAIL OF THE DEVELOPING LOW PRESSURE WILL REMAIN ACROSS THE LOCAL ATLANTIC WATERS AND ACROSS SOUTH FLORIDA TODAY AS THE SYSTEM MOVES SLOWLY OFF TO THE NORTH AND NORTHEAST. MAV GUIDANCE FOR POPS SEEMS TOO LOW CONSIDERING THE DEVELOPMENT ACROSS THE REGION ALREADY THIS MORNING SO WENT CLOSER TO THE MET GUIDANCE FOR POPS. HOWEVER...IT IS POSSIBLE THE MID/UPPER LEVEL CLOUDINESS COULD LIMIT CONVECTION. IN ADDITION...THE REGION IS ON THE SUBSIDENCE SIDE OF THE LOW. A LIGHT WEST TO SOUTHWEST FLOW IS EXPECTED TO CONTINUE ACROSS THE REGION TODAY...AND WITH SEA BREEZE BOUNDARIES POSSIBLY DEVELOPING THIS AFTERNOON...THE FORECAST IS FOR SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION. STORM MOTION IS EXPECTED TO BE SLOW TO THE EAST AND NORTHEAST. LOCALLY HEAVY RAIN IS POSSIBLE AS PRECIPITABLE WATER VALUES REMAIN ABOVE 2 INCHES. A FEW STORMS COULD ALSO BECOME STRONG. WITH THE LIGHT FLOW...WATERSPOUTS ARE POSSIBLE OVER ALL OF THE LOCAL WATERS TODAY. THE LOW PRESSURE IS FORECAST TO MERGE WITH A TROUGH TONIGHT THAT WILL MOVE OFF THE EAST COAST. THE TAIL END MAY REMAIN OVER SOUTH FLORIDA THROUGH MIDNIGHT BEFORE BEGINNING TO DIMINISH. SO ISOLATED SHOWERS AND STORMS ARE POSSIBLE ACROSS THE REGION. LIGHT WESTERLY FLOW WILL CONTINUE THROUGH MONDAY AS HIGH PRESSURE REMAINS SOUTH OF THE REGION AND A TROUGH REMAINS OVER THE EASTERN SEABOARD AND WESTERN ATLANTIC. THIS WILL LEAD TO SCATTERED AFTERNOON CONVECTION EACH DAY. THE WESTERLY WINDS MAY LEAD TO TEMPERATURES REACHING A COUPLE DEGREES ABOVE NORMAL EACH DAY ACROSS THE EAST. THE TROUGH WILL BEGIN TO LIFT OUT ON TUESDAY...AND HIGH PRESSURE WILL SLOWLY BUILD ACROSS THE WESTERN ATLANTIC...WITH THE RIDGE AXIS PUSHING NORTH OF THE REGION BY THE MIDDLE OF THE WEEK. TUESDAY WILL BE A TRANSITION DAY AS THE RIDGE AXIS MOVES OVERHEAD...WITH VERY LIGHT WINDS CONTINUING AND SCATTERED STORMS POSSIBLE ANYWHERE ACROSS THE REGION. EASTERLY FLOW IS FORECAST TO REESTABLISH ITSELF BY MIDWEEK...WITH STORMS CONCENTRATING ACROSS THE INTERIOR AND EAST WEDNESDAY AND THURSDAY. AN UPPER LEVEL LOW MAY APPROACH THE REGION BY THE END OF THE WEEK OR NEXT WEEKEND...AND THIS COULD ENHANCE SHOWER AND THUNDERSTORM ACTIVITY ONCE AGAIN. AVIATION... A FEW SHOWERS ARE DEVELOPING IN THE VICINITY OF KAPF SO PLACED VCSH THERE OVERNIGHT. THERE IS A LESSER CHANCE ALONG THE ATLANTIC COAST EARLY THIS MORNING. SCATTERED SHRA/TSRA IS EXPECTED TO DEVELOP DURING THE AFTERNOON ACROSS SOUTH FL, SO PLACED VCTS ALL TERMINALS THEN. IFR IS POSSIBLE AT ANY GIVEN TERMINAL, BUT IT WOULD BE BRIEF AND CONFIDENCE IS TOO LOW TO PLACE ANYTHING MORE THAN VCTS FOR THIS AFTERNOON AT THIS TIME. LIGHT- CALM WINDS THIS MORNING ARE FORECAST TO BECOMING S-SE EAST COAST (EXCEPT LIKELY REMAINING SW AT KTMB) AND SW AT KAPF AT 5-10 KT. /GREGORIA MARINE... A RATHER TRANQUIL MARINE FORECAST WITH THE REMNANTS OF DORIAN CONTINUING TO MOVE NORTH OF THE LOCAL WATERS OVER THE WEEKEND. HOWEVER...THERE COULD BE LOCALLY ROUGH SEAS NEAR STRONGER STORMS THAT MOVE ACROSS THE LOCAL WATERS TODAY. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 90 76 93 77 / 50 20 30 10 FORT LAUDERDALE 89 78 91 78 / 50 20 20 10 MIAMI 91 78 93 78 / 50 20 30 10 NAPLES 90 76 90 76 / 30 20 20 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MIAMI FL
133 AM EDT SAT AUG 3 2013 .AVIATION...A FEW SHOWERS ARE DEVELOPING IN THE VICINITY OF KAPF SO PLACED VCSH THERE OVERNIGHT. THERE IS A LESSER CHANCE ALONG THE ATLANTIC COAST EARLY THIS MORNING. SCATTERED SHRA/TSRA IS EXPECTED TO DEVELOP DURING THE AFTERNOON ACROSS SOUTH FL, SO PLACED VCTS ALL TERMINALS THEN. IFR IS POSSIBLE AT ANY GIVEN TERMINAL, BUT IT WOULD BE BRIEF AND CONFIDENCE IS TOO LOW TO PLACE ANYTHING MORE THAN VCTS FOR THIS AFTERNOON AT THIS TIME. LIGHT- CALM WINDS THIS MORNING ARE FORECAST TO BECOMING S-SE EAST COAST (EXCEPT LIKELY REMAINING SW AT KTMB) AND SW AT KAPF AT 5-10 KT. /GREGORIA && .PREV DISCUSSION... /ISSUED 756 PM EDT FRI AUG 2 2013/ DISCUSSION... MAIN ADJUSTMENTS TONIGHT ARE JUST FINE TUNING WHERE CONVECTION HAS FIRED ACROSS SOUTH FLORIDA IN COMPARISON TO WHERE THE MODELS ORIGINALLY HAD PLACED IT. CURRENT MODELS KEEP MOST OF THE CONVECTION ALONG THE ATLANTIC COAST, NORTH OF MIAMI. HOWEVER, HAVE KEPT ISOLATED SHOWERS AND THUNDERSTORM ACROSS SOUTH FLORIDA THROUGH THE OVERNIGHT HOURS, DUE TO OUTFLOW BOUNDARIES FLOATING AROUND THROUGHOUT THE CWA. THESE BOUNDARIES COULD ALLOW SOME ISOLATED SHOWERS AND EVEN A THUNDERSTORM TO POP UP TONIGHT. OTHERWISE, ONCE THE MAIN LINE THAT IS BEGINNING TO SHOW SIGNS OF WEAKENING DISSIPATES, THE WEATHER SHOULD BE FAIRLY QUIET ACROSS SOUTH FLORIDA. AVIATION... LINE OF SHRAS/TSRAS IN ASSOCIATION WITH THE REMNANTS OF DORIAN CONTINUES TO SWEEP ACROSS PORTIONS OF NORTHEASTERN BROWARD COUNTY AFFECTING KFXE AND KFLL WHERE ISOLATED MVFR/IFR CONDITIONS MAY BE SEEN BRIEFLY WITHIN TSRAS. LATEST HRRR SHOWS THIS ACTIVITY WEAKENING GRADUALLY OVER THE NEXT FEW HOURS. LIGHT SOUTHWESTERLY FLOW SHOULD PREVAIL OVERNIGHT. ANOTHER ROUND OF SHRAS/TSRAS IS EXPECTED TOMORROW BUT SHOULD BE MAINLY DIURNAL/SEA BREEZE INDUCED ACTIVITY. PREV DISCUSSION... /ISSUED 210 PM EDT FRI AUG 2 2013/ SHORT TERM (TONIGHT-SUNDAY NIGHT)... THE WEAK SURFACE LOW PRESSURE WHICH IS THE REMNANTS OF DORIAN CONTINUES OFF THE EAST FLORIDA COAST DRIFTING VERY SLOWLY TO THE NORTH SNEAKING ITS WAY THROUGH A WEAKNESS IN THE MID LEVEL SUBTROPICAL RIDGE. GLOBAL MODELS IN FAIR AGREEMENT IN LIFTING IT SLOWLY NORTH TONIGHT AND THEN A GRADUAL SHIFT TO THE NORTH-NORTHEAST ON SATURDAY AS IT GETS PICKED UP BY A FRONTAL BOUNDARY MOVING ONTO THE EASTERN SEABOARD. THE DIFFERENCE IN OPINION IS ON JUST HOW THIS WILL IMPACT THE WEATHER PARAMETERS OVER SOUTH FLORIDA ESPECIALLY INTO LATE THIS AFTERNOON AND EVENING. SOME OF THE HIGH RESOLUTION SHORT TERM MODELS ARE PERSISTENT IN DEVELOPING CONVECTION THIS AFTERNOON AFTER 18Z. HOWEVER, THUS FAR THE WEAK MID LEVEL LAPSE RATES AS SHOWN IN THE 12Z MFL SOUNDING HAVE HAMPERED THIS DEVELOPMENT. SO WILL CONTINUE TO MONITOR FOR ANY CHANGES NEEDED TO BE MADE. DUE TO DEVELOPMENT ALONG THE SEA BREEZES AND CONVECTION MOVING ALONG THE EASTERN SIDE OF LAKE OKEECHOBEE GETTING CLOSE TO OUR NORTHEAST ZONES, WILL CONTINUE WITH THE HIGH END POPS FOR NOW. THE FRONTAL BOUNDARY WILL CONTINUE TO SHIFT EAST INTO THE ATLANTIC OVER THE WEEKEND AS A DEEPENING TROUGH CONTINUES TO EVOLVE OVER THE EASTERN U.S. WHILE MAINTAINING THE WEAKNESS IN THE SUBTROPICAL RIDGE OVER SOUTH FLORIDA. THIS WILL ALSO MAINTAIN A DEEP TROPICAL AIRMASS ACROSS THE REGION WITHOUT A SYNOPTIC SYSTEM TO PUSH IT OUT OF THE AREA. FORECAST SOUNDINGS SHOW PWAT CONTINUING TO HOVER AROUND THE 2 INCH MARK. A SURFACE RIDGE WILL ALSO BE STRETCHED ACROSS THE FLORIDA STRAITS THIS WEEKEND AND THIS WILL RESULT IN A WEAK SOUTHWEST TO WEST STEERING FLOW FOR SOUTH FLORIDA SO THE CHANCES FOR CONVECTION WILL BE NEAR AVERAGES FOR EARLY AUGUST WITH THE GREATEST THREAT BEING THE INTERIOR AND EAST COAST METRO AREAS. LONG TERM (MONDAY-FRIDAY)... LOOKING INTO THE MIDDLE TO THE END OF THE WEEK, THE MID LEVEL RIDGE WILL BUILD BACK IN ACROSS THE AREA WITH AT OR SLIGHTLY BELOW POP AVERAGES FOR EARLY AUGUST. HOWEVER, BOTH THE GFS AND ECMWF HAVE BEEN SHOWING A MID LEVEL INVERTED TROUGH ROTATING WEST BELOW THE RIDGE AXIS AND THE LATEST RUN SHOWS IT A LITTLE STRONGER REVERTING SOUTH FLORIDA BACK TO DEEP EASTERLY FLOW BY WEDNESDAY INTO THE END OF THE WEEK. SO FOR NOW, WILL CONTINUE TO SHOW A BROAD BRUSH CHANCE POP FORECAST FOR THE MAINLAND BUT IT COULD END UP WITH HIGHER CHANCES FOR THE INTERIOR AND SOUTHWEST COAST. MARINE... A RATHER TRANQUIL MARINE FORECAST WITH THE LOW PRESSURE TROUGH CONTINUING TO MOVE NORTH OF THE LOCAL WATERS OVER THE WEEKEND. STILL, THERE COULD BE LOCALLY ROUGH SEAS NEAR STRONGER STORMS THAT MAY MOVE OFF THE MAINLAND. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 78 93 79 91 / 20 40 20 40 FORT LAUDERDALE 79 91 79 91 / 20 30 20 40 MIAMI 78 92 78 92 / 20 40 20 40 NAPLES 77 90 78 91 / 20 30 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
349 PM EDT SAT AUG 3 2013 SHORT TERM /TONIGHT THROUGH MONDAY/... LOW AMPLITUDE SHORTWAVE BROUGHT AN AREA OF SHOWERS AND THUNDERSTORMS TO TN EARLIER TODAY...BUT HAS FIZZLED OUT ON ITS WAY INTO NORTH GEORGIA. AHEAD OF THE BOUNDARY...CONVECTION HAS BEEN FIRING ACROSS AL...AND EXPECT MAINLY ISOLATED THUNDERSTORMS /POSSIBLY SCATTERED/ ACROSS NORTH GEORGIA AS WELL. EXPECT MUCH OF THE METRO AREA TO BE QUIET THROUGH THE AFTERNOON AS CONVECTION FOCUSES AHEAD OF THE SHORT WAVE...AND ACROSS FAR SOUTHERN PORTIONS OF THE CWA WHERE THERE IS BETTER INSTABILITY /CAPE 2000-2500 J/KG/. LOCAL WRF AND NAM REALLY KEEP ACTIVITY ACROSS THE AREA TO A MINIMUM...WITH ANY CONVECTION TAPERING OFF BY 00Z TONIGHT. HRRR SOLUTIONS DIFFER IN THE LATEST MODEL RUNS COMPARED TO EARLIER CYCLES...AND NOW ADVERTISE CONVECTION PUSHING INTO THE NORTH METRO AREA BEFORE FIZZLING OUT INTO THE EVENING HOURS. FOR NOW...HAVE CONTINUED WITH SLIGHT CHANCE TO CHANCE POPS ACROSS THE AREAS OF CONCERN...DIMINISHING POPS TO JUST SLIGHT CHANCE OVERNIGHT. HIGH PRESSURE RIDGE BUILDS SOUTH INTO THE REGION SUNDAY...PUSHING A COLD FRONT INTO NORTH GEORGIA AS A RESULT. WITH BEST MOISTURE REMAINING ACROSS THE SOUTHERN HALF OF THE CWA...LATEST MODELS SHOWING BETTER CONSENSUS WITH KEEPING ANY PRECIP CHANCES SOUTH OF THE ATL METRO AREA. HAVE GONE AHEAD AND REMOVED MENTION OF SLIGHT CHANCE POPS NORTH...WHICH MAY BE A LITTLE RISKY...AND PRIMARILY FOCUSED SLIGHT TO CHANCE POPS ACROSS THE FAR SOUTHERN CWA. SOME DISAGREEMENT BETWEEN THE MODELS CONTINUE WITH TIMING AND COVERAGE OF PRECIP INTO THE REGION MONDAY AS PREVIOUSLY MENTIONED FRONTAL BOUNDARY SITS OVER THE AREA AS A DISTURBANCE MOVES INTO THE AREA. HAVE CONTINUED WITH THE SLIGHT CHANCE TO GOOD CHANCE POPS PREVIOUSLY FORECAST...WITH ONLY MINOR ADJUSTMENTS. FOR TEMPERATURES...HAVE GENERALLY GONE WITH A MODEL BLEND. A WELCOME AND NOTICEABLE 3-5 DEGREE COOL DOWN EXPECTED FROM SUNDAY INTO MONDAY WITH HIGH TEMPERATURES WITH THE FRONT. 31 .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... HAVE ONLY MADE A COUPLE OF TWEAKS TO THE POPS ON A COUPLE OF DAYS BUT NOTHING SIGNIFICANT...POPS STILL IN SLIGHT CHANCE OR CHANCE CATEGORY. OTHERWISE THE LONG TERM LOOKS OKAY. TIMING OF A COUPLE OF SHORT WAVES IN THE NORTHWEST FLOW MAY BE TRICKY BUT THE OVERALL PATTERN REMAINS THE SAME. PREVIOUS LONG TERM DISCUSSION IS INCLUDED BELOW. 41 && .PREVIOUS... LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... UNSETTLED WEATHER TO CONTINUE FOR MUCH OF THE LONG TERM. A FRONTAL BOUNDARY WILL BECOME STATIONARY ACROSS SOUTHERN PORTIONS OF THE CWFA SUNDAY NIGHT THROUGH THE FIRST PART OF NEXT WEEK. SEVERAL WAVES OF LOW PRESSURE ARE PROGGED TO MOVE ALONG THE BOUNDARY...EACH HELPING TO SUPPORT THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS THROUGH WEDNESDAY. THE HIGHEST POPS WILL BE DURING THE AFTERNOON AND EARLY EVENING...BUT THE AIRMASS WILL SUPPORT SOME ISOLATED ACTIVITY OVERNIGHT. THE STATIONARY BOUNDARY MAY BECOME DIFFUSE BY THURSDAY. HOWEVER...WITH HIGH PRESSURE OFF THE EASTERN SEABOARD AND SOUTHERLY FLOW BRINGING ABUNDANT MOISTURE NORTHWARD FROM THE GULF...SCT DIURNALLY DRIVEN CONVECTION WILL BE POSSIBLE THURSDAY INTO FRIDAY. THE NEXT COLD FRONT MAY IMPACT THE CWFA BY THE WEEKEND. NLISTEMAA AVIATION... 18Z UPDATE... ISOLATED TS ACTIVITY EXPECTED ACROSS THE AREA THIS AFTERNOON AND EVENING...GENERALLY NORTH OF THE NORTHERN TAF SITES...AND SOUTH OF THE SOUTHERNMOST SITES. SOME INDICATION SHOWERS FROM AL COULD PERSIST AND MOVE INTO NORTH GEORGIA OVERNIGHT...BUT CHANCES TOO LOW TO INCLUDE IN TAF AT THIS TIME. WINDS SHOULD STAY TO THE NW...GENERALLY 8-10KT THIS AFTERNOON...5-8KT OVERNIGHT. SOME LOW END GUSTS TO 14-16KT POSSIBLE THIS AFTERNOON. SCT MVFR POSSIBLE 09-15Z. //ATL CONFIDENCE...18Z UPDATE... HIGH CONFIDENCE ON ALL ELEMENTS. 31 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 92 69 87 / 10 10 5 20 ATLANTA 73 90 71 87 / 20 10 10 20 BLAIRSVILLE 67 85 63 82 / 20 10 5 30 CARTERSVILLE 70 90 67 88 / 20 10 5 20 COLUMBUS 75 95 73 92 / 10 20 10 30 GAINESVILLE 72 89 69 85 / 20 10 5 20 MACON 72 95 71 92 / 10 20 10 20 ROME 70 90 66 89 / 20 10 5 20 PEACHTREE CITY 71 91 68 89 / 20 10 10 20 VIDALIA 75 94 74 92 / 20 30 20 30 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...31 LONG TERM....41 AVIATION...31
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
321 PM EDT SAT AUG 3 2013 .SYNOPSIS... HIGH PRESSURE WILL EXTEND ACROSS THE REGION THROUGH SUNDAY. A BACKDOOR COLD FRONT WILL DROP SOUTH SUNDAY NIGHT AND STALL ACROSS SOUTHEAST GEORGIA MONDAY BEFORE DISSIPATING BY TUESDAY. HIGH PRESSURE WILL THEN REBUILD IN FROM THE NORTHEAST FOR THE REMAINDER OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... SHOWER ACTIVITY CONTINUES TO SLOWLY DEVELOP ALONG THE SEA BREEZE THIS AFTERNOON. LIGHTNING HAS NOT YET BEEN OBSERVED IN ANY OF THE CELLS JUST YET AND GOES-EAST SATELLITE DERIVED SOUNDINGS SUGGEST A SMALL NEGATIVE AREA STILL EXISTS JUST ABOVE 900 MB. AS TEMPERATURES RISE INTO THE 90S...THIS SHOULD ALLOW PARCELS TO MORE EASILY SURPASS THE LEVEL OF FREE CONVECTION /LFC/ AND TAP INTO A LARGE AREA OF CAPE NEARING 3000 J/KG. RAP SOUNDINGS SUPPORT DCAPES IN EXCESS OF 1200 J/KG IN MANY AREAS SO AN ISOLATED SEVERE TSTM OR TWO CAN NOT BE COMPLETELY RULED OUT WITH DAMAGING WINDS AND FREQUENT CLOUD-TO- GROUND LIGHTNING. THERE WILL ALSO A POTENTIAL FOR LOCALIZED FLOODING GIVEN THE WEAK STORM MOTIONS NOTED. PLAN TO MAINTAIN 20-30 PERCENT POPS THROUGH THE EVENING HOURS WITH THE HIGHEST HOURLY GRIDDED POPS CLUSTERED NEAR THE RESULTANT SEA BREEZE CIRCULATION. ONCE CONVECTION DISSIPATES THIS EVENING...EXCEPT A DRY NIGHT WITH ONLY THIN DEBRIS CIRRUS PASSING OVERHEAD. LOWS WILL RANGE FROM THE LOWER 70S WELL INLAND TO AROUND 80 AT THE BEACHES. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... SUNDAY...A DRY NORTHWEST WIND SHOULD KEEP CONDITIONS RAIN-FREE TO START OFF THE WEEK. THE NORTHWEST FLOW WILL LIKELY CONTRIBUTE TO WARMER THAN NORMAL TEMPS AS THE SEABREEZE REMAINS PINNED ALONG THE COAST THROUGH EARLY AFTERNOON. LATEST MOS GUIDANCE ALONG WITH 1000-850 MB THICKNESSES SUGGEST OVERALL HIGH TEMPS IN THE LOW TO MID 90S AWAY FROM THE IMMEDIATE COAST. GIVEN THE DURATION OF THE PINNED SEABREEZE ALONG THE COAST...TEMPS COULD PEAK NEAR 90 ALONG THE BEACHES. HOWEVER...WARMEST TEMPS WILL LIKELY OCCUR OVER SOUTHEAST GEORGIA WHERE COMPRESSIONAL HEATING TAKES PLACE AHEAD OF A BACKDOOR COLD FRONT APPROACHING THE REGION FROM THE NORTH/NORTHEAST. A SLIGHT CHANCE TO CHANCE OF SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST SUNDAY AFTERNOON/EVENING AS THE BACKDOOR COLD FRONT APPROACHES FROM THE NORTH/NORTHEAST AND BEGINS TO STALL OVER OR NEAR SOUTHEAST GEORGIA SUNDAY NIGHT. PRECIP CHANCES AND COVERAGE WILL BE HIGHEST SUNDAY EVENING INTO THE EARLY OVERNIGHT HOURS IN SOUTHEAST GEORGIA WHERE MOISTURE REMAINS HIGHEST WITH PWATS NEAR 2.00 INCHES NEAR THE VICINITY OF STALLED FRONT. OVERNIGHT LOWS SHOULD RANGE IN THE LOW 70S INLAND TO MID/UPPER 70S ALONG THE COAST. MONDAY AND TUESDAY....A LARGE MID LVL RIDGE OVER THE SOUTH CENTRAL UNITED STATES WILL GRADUALLY EXPAND OVER THE SOUTHEAST EARLY NEXT WEEK AS THE STALLED SFC BOUNDARY LINGERS OVER SOUTHERN PORTIONS OF THE FORECAST AREA MONDAY BEFORE DISSIPATING AS SFC HIGH PRESSURE SLIDES IN FROM THE NORTH/NORTHEAST ON TUESDAY. LIGHT ONSHORE WINDS SUPPORT ABUNDANT LOW LVL MOISTURE OVER THE SOUTHEAST EACH DAY...WITH A FEW SHOWERS AND/OR THUNDERSTORMS ALONG AN INLAND MOVING SEABREEZE EACH AFTERNOON. THE GREATEST CONCENTRATION OF CONVECTION IS EXPECTED OVER SOUTHEAST GEORGIA NEAR THE DISSIPATING BOUNDARY AND INLAND MOVING SEABREEZE. HIGH TEMPS WILL BE SLIGHTLY COOLER THAN PREVIOUS DAYS...WITH 1000-850 MB THICKNESSES SUPPORTING OVERALL HIGH TEMPS IN THE UPPER 80S TO LOWER 90S UNDER PARTLY SUNNY SKIES. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... DEEP LAYER RIDGING BUILDS ACROSS THE SOUTHEAST U.S. AND INTO THE ATLANTIC WATERS. LOW LEVEL SE FLOW WILL PREVAIL THROUGH THE PERIOD WITH BEST MOISTURE AND CONVERGENCE EXPECTED TO FOCUS INLAND. MAINLY AFTERNOON AND EARLY EVENING CONVECTION PUSHING INLAND EACH DAY. MODEL CROSS SECTIONS SHOW MARGINAL DEEP LAYER MOISTURE...AND ALONG WITH RIDGING ALOFT...EXPECT CONVECTION TO BE SCATTERED AT BEST EACH AFTERNOON. HAVE KEPT LOW END CHANCE POPS THROUGH THE PERIOD. TEMPS AROUND NORMAL. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... MAINLY VFR CONDITIONS ARE EXPECTED TO PREVAIL TODAY...BUT PERIODIC REDUCTIONS ARE POSSIBLE AS SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP ALONG THE SEA BREEZE. CHANCES FOR THUNDERSTORMS APPEAR MORE FAVORABLE AT KCHS GIVEN THE LATEST RADAR TRENDS. THEREFORE...HAVE INCLUDED A TSRA TEMPO GROUP STARTING AROUND 19Z. LESS CONVECTIVE COVERAGE IS EXPECTED CLOSER TO KSAV. THEREFORE...WILL EXCLUDED TS IN TAFS FOR NOW AND WILL AMEND IF NECESSARY. ANY LINGERING CONVECTION SHOULD DIMINISH AROUND SUNSET...ALLOWING VFR CONDITIONS TO PREVAIL. EXTENDED AVIATION OUTLOOK...ISOLATED TO SCATTERED AFTERNOON SHOWERS/THUNDERSTORMS POSSIBLE EACH DAY...WITH A CHANCE OF BRIEF MVFR CIGS/VSBYS. CHANCES OF MVFR CIGS/VSBYS SHOULD BE HIGHEST AT THE SAV TERMINAL SUNDAY EVENING/NIGHT AS A BACKDOOR COLD FRONT STALLS OVER THE AREA. && .MARINE... TONIGHT...LIGHT WINDS THIS AFTERNOON WILL GRADUALLY VEER SOUTHWEST AND INCREASE TO 10-15 KT THIS EVENING/OVERNIGHT AS A COLD FRONT DRAWS CLOSER TO THE REGION. SEAS WILL RESPOND A JUST A LITTLE... BUT STILL EXPECT SEAS TO RANGE FROM 2-4 FT...HIGHEST OVER THE OFFSHORE LEGS. MONDAY THROUGH THURSDAY...CONDITIONS WILL REMAIN WELL BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THE MIDDLE OF NEXT WEEK. IN GENERAL...SOUTHWEST WINDS WILL DOMINATE THE WATERS SUNDAY WHILE REMAINING AT OR BELOW 15 KTS. A BACKDOOR COLD FRONT WILL THEN REACH THE WATERS SUNDAY NIGHT...THUS VEERING WINDS TO NORTH/NORTHEAST WITH SPEEDS NEAR 15 KTS AT TIMES. LIGHT WINDS WILL CONTINUE TO VEER AND BECOME ONSHORE BY MONDAY AS THE FRONT STALLS AND DISSIPATES ALONG OR NEAR SOUTHERN GEORGIA WATERS ON TUESDAY. SEAS WILL RANGE FROM 1-3 FT...HIGHEST OVER OUTER GEORGIA WATERS. HIGH PRESSURE WILL THEN SETTLE OVER THE WATERS THROUGH MIDWEEK WITH POSSIBLY LONGER PERIOD SWELLS DURING THIS TIME FRAME DUE TO LONGER FETCH AND THE DURATION OF SOUTHEAST FLOW. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ ST/JHP/DPB
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1251 PM CDT SAT AUG 3 2013 .DISCUSSION... 339 AM CDT THERE ARE NO BIG CONCERNS FOR THE NEXT COUPLE OF DAYS AS COOL AND DRY HIGH PRESSURE DOMINATES ACROSS THE AREA. HOWEVER...FORECAST CONCERNS FOR SHOWERS AND THUNDERSTORMS INCREASE AGAIN EARLY NEXT WEEK. THEREFORE THE MAIN FORECAST CONCERNS WILL BE WITH CONVECTIVE CHANCES AND TEMPERATURES IN THE EXTENDED. CURRENTLY A COLD FRONT IS SAGGING SOUTHWARD ACROSS CENTRAL PORTIONS OF ILLINOIS AND INDIANA. SHOWER AND THUNDERSTORM ACTIVITY HAS ABATED...AND SHIFTED MOSTLY OUT OF MY AREA...WITH ONLY A FEW LINGERING SHOWERS FAR SOUTH. OTHERWISE...SKIES ARE CLEARING ACROSS SOUTHERN WISCONSIN AND FAR NORTHERN ILLINOIS...WITH DEW POINTS DROPPING INTO THE LOWER 50S. THIS TREND SHOULD CONTINUE ACROSS MY ENTIRE AREA BY MID MORNING. SURFACE HIGH PRESSURE...CENTERED OVER NORTH DAKOTA AND INTO THE PRAIRIE PROVIDENCES OF CANADA...WILL PRODUCE A NORTHERLY FLOW ACROSS THE AREA TODAY. TEMPERATURES LOOK TO TOP OUT IN THE UPPER 70S TO THE LOW 80S AREA-WIDE...WITH THE EXCEPTION OF MIDDLE 70S LAKESIDE. TEMPERATURES TONIGHT WILL LIKELY RADIATE EFFICIENTLY WITH MOSTLY CLEAR SKIES AND LIGHT WINDS...AS THE SURFACE HIGH DROPS SOUTHEASTWARD ACROSS MINNESOTA AND WISCONSIN. THIS SHOULD RESULT IN A CHILLY NIGHT...WITH TEMPERATURES FALLING INTO THE LOWER 50S AWAY FROM CHICAGO. SUNDAY WILL ALSO BE PLEASANT WITH TEMPERATURES MAINLY IN THE MID TO UPPER 70S. THINGS BEGINNING TO GET MORE ACTIVE BY MONDAY AS THE SURFACE HIGH SHIFT TO THE EAST AND ALLOWS THE LOWER LEVEL FLOW TO BECOME SOUTHERLY AGAIN. THIS SHOULD ALLOW MOISTURE TO MAKE A QUICK RETURN TO THE AREA. THIS IN COMBINATION WITH AN FAST AND ACTIVE NORTHWESTERLY UPPER LEVEL LEVEL FLOW PATTERN...WILL SET THE STAGE FOR INCREASES IN SHOWERS AND THUNDERSTORMS. IT APPEARS THE FIRST UPPER LEVEL DISTURBANCE COULD INDUCE ENOUGH LOW LEVEL RESPONSE TO RESULT IN SHOWERS/STORMS AS EARLY AS MONDAY. I ADDED SLIGHT CHANCE POPS DURING THE DAY ACROSS MOST OF THE AREA TO ACCOUNT FOR THIS POSSIBILITY. THE NEXT AND MORE SIGNIFICANT FORECAST ISSUE WILL BE THE SIGNIFICANT STORM SYSTEM...WHICH THE MODELS ARE SUGGESTING WILL DEVELOP ACROSS THE UPPER MIDWEST AND INTO WESTERN ONTARIO TUESDAY AND TUESDAY NIGHT AS A SIGNIFICANT UPPER LOW GETS DISLODGED FROM THE HUDSON BAY REGION. THIS SYSTEM LOOKS TO SET UP A PERIOD OF POSSIBLY SIGNIFICANT CONVECTION ACROSS THE AREA...ALONG WITH A PERIOD OF WARMER WEATHER TUESDAY AND WEDNESDAY. THERE ARE UNCERTAINTIES IN THE FINNER SCALE DETAILS OF THIS SYSTEM. HOWEVER...IT DOES APPEAR THAT WARMER CONDITIONS WILL SET UP FOR TUESDAY...AND POTENTIAL INTO WEDNESDAY AS WELL AS SOUTHERLY FLOW AHEAD OF THE DEVELOPING LOW...WILL RESULT IN AN INFLUX OF A WARMER...MORE HUMID AIRMASS. THE MODEL GUIDANCE APPEARS TO BE UNDERDOING THE WARM FOR TUESDAY AND POSSIBLY WEDNESDAY AS WELL. ALTHOUGH THERE WILL BE PERIOD OF CONVECTION AROUND...IT APPEARS TUESDAY LOOKS TO BE A GOOD CANDIDATE FOR TEMPERATURES TOPPING OUT IN THE MID TO UPPER 80S...AS 850 AND 925 MB TEMPERATURES ARE PROGGED TO BE AROUND 18 AND 22 DEGREES C...RESPECTIVELY. TEMPERATURES ON WEDNESDAY COULD BE JUST AS WARM. HOWEVER...DIFFERENCES AND UNCERTAINTIES ON THE EXACT TIMING OF THE COLD FRONTAL PASSAGE ON WEDNESDAY COULD COMPLICATE THINGS. IN SPITE OF THIS...I DID WARM TEMPERATURES INTO THE LOW TO MID 80S FOR BOTH TUESDAY AND WEDNESDAY. ASIDE FROM TEMPERATURES...IT ALSO APPEARS THERE COULD BE A PERIOD OF POSSIBLY SOME SEVERE CONVECTION SOMETIME TUESDAY NIGHT OR WEDNESDAY. THIS WILL BE AN AREA OF FOCUS FOR THE NEXT FEW DAYS...AS UNCERTAINTY IS TOO HIGH AT THIS STAGE TO PIN POINT THE EXTENT OF THE SEVERE THREAT LOCALLY. HOWEVER...IT DOES APPEAR THAT THE DYNAMICS OF THIS RAPIDLY DEVELOPING SYSTEM WILL BE SUPPORTIVE FOR STRONG CONVECTION...FOR AREAS NOT TOO FAR TO THE NORTH OF US. THIS WOULD ALSO INCLUDE A THREAT FOR VERY HEAVY RAINFALL GIVEN THAT PWATS WILL LIKELY CLIMB ABOVE 1.6 INCHES IN THE WARM SECTOR OF THIS STORM SYSTEM. ONCE THE COLD FRONT PASSES BY LATE WEDNESDAY...COOLER AND DRIER AIR WILL AGAIN MAKE A RETURN TO THE AREA FOR A PERIOD LATER NEXT WEEK. I WENT WITH A DRY FORECAST FOR THURSDAY AND FRIDAY...AS IT APPEARS THE FRONT SHOULD DROP FAR ENOUGH SOUTH OF THE AREA TO KEEP THE THREAT FOR RAIN VERY LOW. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * ORD WIND DIRECTION SOMEWHAT VARIABLE FROM NNW TO NE BUT STILL BELIEVE PREVAILING TREND WILL FAVOR NORTHEAST QUADRANT. * CONSIDERED LOWER VSBYS OVERNIGHT BUT AM NOT SEEING STRONG ENOUGH SIGNALS AT THIS TIME TO INCLUDE IN TAFS. LENNING //DISCUSSION...UPDATED 18Z... LOCAL EFFECTS FROM SURFACE HEATING AND THE LAKE BREEZE FORMATION ARE PRIMARY INFLUENCES THIS AFTERNOON. HIGH PRESSURE SLIDING IN FROM THE NORTHWEST SHOULD FURTHER REINFORCE THE LAKE BREEZE TRENDS AND FAVOR PREVAILING NORTHEASTERLY WINDS AT ORD AND MDW. WITH SUCH A WEAK PRESSURE GRADIENT AND DECENT MOISTURE IN THE AREA...CONSIDERED ADDING REDUCED VSBYS OVERNIGHT. LATEST DEWPOINT TRENDS FROM OBS AND MODELS SEEM TO BE ON THE WAY DOWN...AND SURFACE TEMPERATURES OVERNIGHT MAY END UP BEING TOO WARM TO SUPPORT BOUNDARY LAYER SATURATION. HIGH PRESSURE WILL AGAIN DOMINATE TOMORROW...WITH WINDS VERY SLOWLY TURNING SOUTH OR SOUTHEAST LATE TOMORROW EVENING. LENNING //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN VFR THIS AFTERNOON AND PRIMARILY NORTHEAST QUADRANT FOR WINDS. LENNING //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...VFR. MONDAY...CHC OF TSRA WITH MVFR CIGS POSSIBLE DURING THE AFTERNOON AND NIGHT. TUESDAY-WEDNESDAY...CHC OF TSRA. THURSDAY-FRIDAY...VFR LIKELY. MTF && .MARINE... 234 AM CDT NORTHERLY FLOW WILL PREVAIL OVER THE LAKE TODAY INTO THE DAY SUNDAY...HELPED BY A SECONDARY COLD FRONT MOVING DOWN THE LAKE TONIGHT. SPORADIC 20 KT GUSTS ARE POSSIBLE TODAY OVER THE LAKE BUT MUCH OF THE TIME SHOULD REMAIN 10 TO 15 KT. HIGH PRESSURE WILL BUILD FROM THE UPPER MIDWEST TO LAKE MI ON SUNDAY AND INTO EARLY MONDAY...OFFERING LAKE BREEZE PUSHES IN THE NEARSHORE AREAS DURING THE AFTERNOONS. SOUTHERLY FLOW WILL THEN ENVELOP THE LAKE AT LEAST ON TUESDAY AND POTENTIALLY INTO WEDNESDAY AS DEEP LOW PRESSURE TAKES SHAPE ACROSS SOUTH CENTRAL CANADA AND SWINGS A SURFACE TROUGH EASTWARD. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1231 PM CDT Sat Aug 3 2013 .DISCUSSION... ISSUED 956 AM CDT Sat Aug 3 2013 Cold front has settled into south-central Illinois this morning...with latest obs showing it just south of I-70. To the south of the front...mostly cloudy and humid conditions prevail across southeast Illinois where dewpoints are hovering around 70 degrees. Meanwhile...a cooler/drier airmass has settled into much of central Illinois north of the boundary...as evidenced by 14z/9am dewpoints in the upper 50s/lower 60s across the northern KILX CWA. HRRR model suggests the potential for isolated showers/thunder in the vicinity of the slow-moving cold front today. No evidence is seen of this yet...as main precip event is ongoing much further south across the Ozarks. Given high dewpoint air and presence of boundary...will maintain slight chance POPs south of I-70 throughout the day. Further north...made some changes to sky cover to feature sunnier conditions. Also raised afternoon highs by a degree or two. Zone update has already been issued. BARNES && .AVIATION... ISSUED 1231 PM CDT Sat Aug 3 2013 VFR conditions will prevail through the entire 18z TAF period...as high pressure dominates the weather across central Illinois. Latest visible satellite imagery is showing CU-field developing mainly across the east...which matches very well with the 12z NAM CU-rule. Will include SCT CU with bases between 3500 and 5000ft...but will carry a tempo group for BKN cloud cover at times at both KDEC and KCMI this afternoon. Diurnal cloud cover will fade away toward sunset...with only a few high/thin clouds expected overnight. Winds will be northerly at less than 10kt this afternoon...then will veer to the E/NE and remain light by Sunday morning. BARNES && .PREV DISCUSSION... ISSUED 330 AM CDT Sat Aug 3 2013 SHORT TERM...Today through Monday night 00z short range models are in fair agreement this weekend and then diverge during next work week as more unsettled weather pattern sets up across IL. Will use a blend for this forecast package with handling weather systems during next week. A frontal boundary was pushing southeast toward I-70 in central IN and southeast IL into central MO early this morning. Showers have been diminishing over east central IL past couple of hours and brought up to half to 1 inch rains to some areas from I-74 north since Friday evening. Cold front to push through southeast IL during this morning and have isolated showers and thunderstorms in southeast IL today, mainly this morning. Clouds to decrease from north to south during the day as skies become partly to mostly sunny with northern areas enjoying more sunshine today. Less humid air filters into northern areas as dewpoints slip into the lower 60s while southeast IL stays humid today with dewpoints in the upper 60s and lower 70s. Highs in the lower 80s today with Lawrenceville around 85F. 1024 mb high pressure over Saskatchewan and western Manitoba into ND to settle southeast into the Midwest during this weekend...and be over northeast IL by Sunday morning. This to bring fair weather to the region today and Sunday with mostly clear skies and more comfortable humidity levels. Lows tonight in the mid to upper 50s and highs Sunday in the upper 70s and lower 80s with dewpoints in the upper 50s and lower 60s. Have slight chance of showers and thunderstorms after midnight Sunday night over western areas due to waa pattern setting up as high pressure drifts east of IL across the Ohio Valley. Slight chance of showers and thunderstorms gradually spreads east across the area during Monday and Monday night in WAA pattern. LONG TERM...Tuesday through Saturday A rather unsettled weather pattern expected during Tuesday through Friday across central and southeast IL as disturbances in wnw upper level flow track across the midwest and interact with a warmer and more humid air mass during middle of next week. Increased temps a few degrees Tue & Wed. Best chances of showers and thunderstorms appears to be Tuesday night after midnight through Wed and shifting into southern areas during Wed night and Thu as a cold front slips southward through the region. Cooler temperatures expected later next week with dry weather returning by weeks end on Friday night & Sat. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1105 AM CDT SAT AUG 3 2013 .DISCUSSION... 339 AM CDT THERE ARE NO BIG CONCERNS FOR THE NEXT COUPLE OF DAYS AS COOL AND DRY HIGH PRESSURE DOMINATES ACROSS THE AREA. HOWEVER...FORECAST CONCERNS FOR SHOWERS AND THUNDERSTORMS INCREASE AGAIN EARLY NEXT WEEK. THEREFORE THE MAIN FORECAST CONCERNS WILL BE WITH CONVECTIVE CHANCES AND TEMPERATURES IN THE EXTENDED. CURRENTLY A COLD FRONT IS SAGGING SOUTHWARD ACROSS CENTRAL PORTIONS OF ILLINOIS AND INDIANA. SHOWER AND THUNDERSTORM ACTIVITY HAS ABATED...AND SHIFTED MOSTLY OUT OF MY AREA...WITH ONLY A FEW LINGERING SHOWERS FAR SOUTH. OTHERWISE...SKIES ARE CLEARING ACROSS SOUTHERN WISCONSIN AND FAR NORTHERN ILLINOIS...WITH DEW POINTS DROPPING INTO THE LOWER 50S. THIS TREND SHOULD CONTINUE ACROSS MY ENTIRE AREA BY MID MORNING. SURFACE HIGH PRESSURE...CENTERED OVER NORTH DAKOTA AND INTO THE PRAIRIE PROVIDENCES OF CANADA...WILL PRODUCE A NORTHERLY FLOW ACROSS THE AREA TODAY. TEMPERATURES LOOK TO TOP OUT IN THE UPPER 70S TO THE LOW 80S AREA-WIDE...WITH THE EXCEPTION OF MIDDLE 70S LAKESIDE. TEMPERATURES TONIGHT WILL LIKELY RADIATE EFFICIENTLY WITH MOSTLY CLEAR SKIES AND LIGHT WINDS...AS THE SURFACE HIGH DROPS SOUTHEASTWARD ACROSS MINNESOTA AND WISCONSIN. THIS SHOULD RESULT IN A CHILLY NIGHT...WITH TEMPERATURES FALLING INTO THE LOWER 50S AWAY FROM CHICAGO. SUNDAY WILL ALSO BE PLEASANT WITH TEMPERATURES MAINLY IN THE MID TO UPPER 70S. THINGS BEGINNING TO GET MORE ACTIVE BY MONDAY AS THE SURFACE HIGH SHIFT TO THE EAST AND ALLOWS THE LOWER LEVEL FLOW TO BECOME SOUTHERLY AGAIN. THIS SHOULD ALLOW MOISTURE TO MAKE A QUICK RETURN TO THE AREA. THIS IN COMBINATION WITH AN FAST AND ACTIVE NORTHWESTERLY UPPER LEVEL LEVEL FLOW PATTERN...WILL SET THE STAGE FOR INCREASES IN SHOWERS AND THUNDERSTORMS. IT APPEARS THE FIRST UPPER LEVEL DISTURBANCE COULD INDUCE ENOUGH LOW LEVEL RESPONSE TO RESULT IN SHOWERS/STORMS AS EARLY AS MONDAY. I ADDED SLIGHT CHANCE POPS DURING THE DAY ACROSS MOST OF THE AREA TO ACCOUNT FOR THIS POSSIBILITY. THE NEXT AND MORE SIGNIFICANT FORECAST ISSUE WILL BE THE SIGNIFICANT STORM SYSTEM...WHICH THE MODELS ARE SUGGESTING WILL DEVELOP ACROSS THE UPPER MIDWEST AND INTO WESTERN ONTARIO TUESDAY AND TUESDAY NIGHT AS A SIGNIFICANT UPPER LOW GETS DISLODGED FROM THE HUDSON BAY REGION. THIS SYSTEM LOOKS TO SET UP A PERIOD OF POSSIBLY SIGNIFICANT CONVECTION ACROSS THE AREA...ALONG WITH A PERIOD OF WARMER WEATHER TUESDAY AND WEDNESDAY. THERE ARE UNCERTAINTIES IN THE FINNER SCALE DETAILS OF THIS SYSTEM. HOWEVER...IT DOES APPEAR THAT WARMER CONDITIONS WILL SET UP FOR TUESDAY...AND POTENTIAL INTO WEDNESDAY AS WELL AS SOUTHERLY FLOW AHEAD OF THE DEVELOPING LOW...WILL RESULT IN AN INFLUX OF A WARMER...MORE HUMID AIRMASS. THE MODEL GUIDANCE APPEARS TO BE UNDERDOING THE WARM FOR TUESDAY AND POSSIBLY WEDNESDAY AS WELL. ALTHOUGH THERE WILL BE PERIOD OF CONVECTION AROUND...IT APPEARS TUESDAY LOOKS TO BE A GOOD CANDIDATE FOR TEMPERATURES TOPPING OUT IN THE MID TO UPPER 80S...AS 850 AND 925 MB TEMPERATURES ARE PROGGED TO BE AROUND 18 AND 22 DEGREES C...RESPECTIVELY. TEMPERATURES ON WEDNESDAY COULD BE JUST AS WARM. HOWEVER...DIFFERENCES AND UNCERTAINTIES ON THE EXACT TIMING OF THE COLD FRONTAL PASSAGE ON WEDNESDAY COULD COMPLICATE THINGS. IN SPITE OF THIS...I DID WARM TEMPERATURES INTO THE LOW TO MID 80S FOR BOTH TUESDAY AND WEDNESDAY. ASIDE FROM TEMPERATURES...IT ALSO APPEARS THERE COULD BE A PERIOD OF POSSIBLY SOME SEVERE CONVECTION SOMETIME TUESDAY NIGHT OR WEDNESDAY. THIS WILL BE AN AREA OF FOCUS FOR THE NEXT FEW DAYS...AS UNCERTAINTY IS TOO HIGH AT THIS STAGE TO PIN POINT THE EXTENT OF THE SEVERE THREAT LOCALLY. HOWEVER...IT DOES APPEAR THAT THE DYNAMICS OF THIS RAPIDLY DEVELOPING SYSTEM WILL BE SUPPORTIVE FOR STRONG CONVECTION...FOR AREAS NOT TOO FAR TO THE NORTH OF US. THIS WOULD ALSO INCLUDE A THREAT FOR VERY HEAVY RAINFALL GIVEN THAT PWATS WILL LIKELY CLIMB ABOVE 1.6 INCHES IN THE WARM SECTOR OF THIS STORM SYSTEM. ONCE THE COLD FRONT PASSES BY LATE WEDNESDAY...COOLER AND DRIER AIR WILL AGAIN MAKE A RETURN TO THE AREA FOR A PERIOD LATER NEXT WEEK. I WENT WITH A DRY FORECAST FOR THURSDAY AND FRIDAY...AS IT APPEARS THE FRONT SHOULD DROP FAR ENOUGH SOUTH OF THE AREA TO KEEP THE THREAT FOR RAIN VERY LOW. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * NO MAJOR CONCERNS THIS AFTERNOON/EVENING. * SOME UNCERTAINTY WHETHER GUSTS WILL DEVELOP...BUT ONLY WOULD EXPECT MID TEENS. * ALSO SOME UNCERTAINTY REGARDING CEILINGS...BUT LIKELY TO STAY SCATTERED AND CERTAINLY VFR. LENNING //DISCUSSION...UPDATED 12Z... HIGH PRESSURE WILL CONTINUE TO EXPAND FROM THE UPPER MIDWEST INTO THE WESTERN GREAT LAKES TODAY BEHIND A DEPARTING COOL FRONT. THE ORIENTATION OF THE HIGH WILL FAVOR NORTHERLY WINDS TO BECOME MORE NORTHEASTERLY ACROSS CHICAGOLAND LATE THIS MORNING AND INTO THE AFTERNOON...AND EVEN MORE PRONOUNCED TO POTENTIALLY ENE GIVEN THE LAKE ORIENTATION AND CLIMATOLOGY OF SUCH FLOW. THE SPEEDS WILL LIKELY APPROACH 10 KT AND HOLD AS SUCH THROUGH THE AFTERNOON. A WEAK SECONDARY FRONT WILL DROP SOUTH THROUGH THE REGION TONIGHT AND THAT COULD KEEP A LIGHT NORTHERLY COMPONENT. IF NOT THOUGH...PATCHY FOG DEVELOPMENT MAY BE SEEN AS IT WAS THIS MORNING ACROSS THE REGION...ESPECIALLY AT FAVORED LOW-LYING OPEN AIRPORTS. HIGH PRESSURE ON SUNDAY WILL ALLOW FOR AN EVEN MORE PRONOUNCED LAKE PUSH. //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM TO HIGH CONFIDENCE IN ALL ELEMENTS. LENNING //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...VFR. MONDAY...CHC OF TSRA WITH MVFR CIGS POSSIBLE DURING THE AFTERNOON AND NIGHT. TUESDAY-WEDNESDAY...CHC OF TSRA. THURSDAY-FRIDAY...VFR LIKELY. MTF && .MARINE... 234 AM CDT NORTHERLY FLOW WILL PREVAIL OVER THE LAKE TODAY INTO THE DAY SUNDAY...HELPED BY A SECONDARY COLD FRONT MOVING DOWN THE LAKE TONIGHT. SPORADIC 20 KT GUSTS ARE POSSIBLE TODAY OVER THE LAKE BUT MUCH OF THE TIME SHOULD REMAIN 10 TO 15 KT. HIGH PRESSURE WILL BUILD FROM THE UPPER MIDWEST TO LAKE MI ON SUNDAY AND INTO EARLY MONDAY...OFFERING LAKE BREEZE PUSHES IN THE NEARSHORE AREAS DURING THE AFTERNOONS. SOUTHERLY FLOW WILL THEN ENVELOP THE LAKE AT LEAST ON TUESDAY AND POTENTIALLY INTO WEDNESDAY AS DEEP LOW PRESSURE TAKES SHAPE ACROSS SOUTH CENTRAL CANADA AND SWINGS A SURFACE TROUGH EASTWARD. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 956 AM CDT Sat Aug 3 2013 .DISCUSSION... ISSUED 956 AM CDT Sat Aug 3 2013 Cold front has settled into south-central Illinois this morning...with latest obs showing it just south of I-70. To the south of the front...mostly cloudy and humid conditions prevail across southeast Illinois where dewpoints are hovering around 70 degrees. Meanwhile...a cooler/drier airmass has settled into much of central Illinois north of the boundary...as evidenced by 14z/9am dewpoints in the upper 50s/lower 60s across the northern KILX CWA. HRRR model suggests the potential for isolated showers/thunder in the vicinity of the slow-moving cold front today. No evidence is seen of this yet...as main precip event is ongoing much further south across the Ozarks. Given high dewpoint air and presence of boundary...will maintain slight chance POPs south of I-70 throughout the day. Further north...made some changes to sky cover to feature sunnier conditions. Also raised afternoon highs by a degree or two. Zone update has already been issued. BARNES && .AVIATION... ISSUED 640 AM CDT Sat Aug 3 2013 The showers associated with the cold front have advanced east of all the terminal sites, so no mention of precip is in any of the tafs. We did add some mvfr fog to KSPI, but none of the other taf sites were experiencing fog, nor are expected to this morning. Weak high pressure advancing into central IL behind the front will help to clear out low clouds, and provide light north-northeast winds. High cirrus clouds from a storm complex in Missouri will cover our area this morning, but mostly sunny skies should develop by afternoon. Forecast soundings are not strong on fog indicators for late tonight, so we did not include any mention of fog at the end of this taf period. SHIMON && .PREV DISCUSSION... ISSUED 330 AM CDT Sat Aug 3 2013 SHORT TERM...Today through Monday night 00z short range models are in fair agreement this weekend and then diverge during next work week as more unsettled weather pattern sets up across IL. Will use a blend for this forecast package with handling weather systems during next week. A frontal boundary was pushing southeast toward I-70 in central IN and southeast IL into central MO early this morning. Showers have been diminishing over east central IL past couple of hours and brought up to half to 1 inch rains to some areas from I-74 north since Friday evening. Cold front to push through southeast IL during this morning and have isolated showers and thunderstorms in southeast IL today, mainly this morning. Clouds to decrease from north to south during the day as skies become partly to mostly sunny with northern areas enjoying more sunshine today. Less humid air filters into northern areas as dewpoints slip into the lower 60s while southeast IL stays humid today with dewpoints in the upper 60s and lower 70s. Highs in the lower 80s today with Lawrenceville around 85F. 1024 mb high pressure over Saskatchewan and western Manitoba into ND to settle southeast into the Midwest during this weekend...and be over northeast IL by Sunday morning. This to bring fair weather to the region today and Sunday with mostly clear skies and more comfortable humidity levels. Lows tonight in the mid to upper 50s and highs Sunday in the upper 70s and lower 80s with dewpoints in the upper 50s and lower 60s. Have slight chance of showers and thunderstorms after midnight Sunday night over western areas due to waa pattern setting up as high pressure drifts east of IL across the Ohio Valley. Slight chance of showers and thunderstorms gradually spreads east across the area during Monday and Monday night in WAA pattern. LONG TERM...Tuesday through Saturday A rather unsettled weather pattern expected during Tuesday through Friday across central and southeast IL as disturbances in wnw upper level flow track across the midwest and interact with a warmer and more humid air mass during middle of next week. Increased temps a few degrees Tue & Wed. Best chances of showers and thunderstorms appears to be Tuesday night after midnight through Wed and shifting into southern areas during Wed night and Thu as a cold front slips southward through the region. Cooler temperatures expected later next week with dry weather returning by weeks end on Friday night & Sat. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1250 AM CDT SAT AUG 3 2013 .DISCUSSION... 911 PM CDT EVENING UPDATE: STRONG SHORTWAVE/MID LEVEL JET STREAK APPARENT ON WATER VAPOR PUSHING IN FROM IOWA HAS SUSTAINED CONVECTION THAT FORMED ALONG MOISTURE CONVERGENCE AXIS SOUTH OF INTERSTATE 80. THIS IS IN AN AIR MASS THAT IS JUICY SOUTH OF COLD FRONT SINKING SOUTHWARD...WITH PWATS OF 1.82 INCHES AND 1.72 INCHES RESPECTIVELY ON 00Z DVN AND ILX RAOBS. RESULT HAS BEEN A MUCH NEEDED HEAVY RAIN EVENT FOR MANY AREAS SOUTH OF INTERSTATE 80. THOUGH EAST-WEST ORIENTATION OF MAIN BAND IS CONCERNING...PRECLUDING A BIGGER FLOOD THREAT IS DRY ANTECEDENT CONDITIONS AND THE SLOW BUT STEADY SOUTHWARD PROGRESS. NONETHELESS...HOURLY RADAR ESTIMATES OF 1 TO 1.5 INCHES PER HOUR COULD RESULT IN PONDING ON SOME ROADWAYS. PRECIP LOADING IN MOST INTENSE CORES COULD RESULT IN BRIEF GUSTY WINDS BUT BIGGEST CONCERN IS THE HEAVY RAINFALL AND FAIRLY FREQUENT CLOUD TO GROUND LIGHTNING. TO THE NORTH...AREA OF SPOTTY LIGHT RAIN/DRIZZLE WILL PUSH EASTWARD AND LIKELY FIZZLE WITH TIME. MADE MINOR TWEAKS TO POPS FOR PART OF THE EVENING AND OVERNIGHT...BUT REMAINDER OF FORECAST APPEARS TO BE IN GOOD SHAPE...WITH ONLY TWEAKS TO HOURLY TRENDS FOR TEMPS AND DEWPOINTS. RC //PREV DISCUSSION... 248 PM CDT THIS AFTERNOON AND TONIGHT... A SURFACE TROUGH IS DRAPED FROM NORTHERN LAKE MICHIGAN SOUTHWEST ACROSS SOUTHERN WISCONSIN AND INTO NORTHWESTERN ILLINOIS. AGITATED CU FIELD HAS DEVELOPED OUT AHEAD OF THE TROUGH FROM DOWNTOWN CHICAGO WEST ACROSS FAR NORTHERN LA SALLE COUNTY AND SOUTHERN LEE COUNTY. HAVE RECENTLY SEEN THE FIRST RETURNS ON RADAR DEVELOPING IN THIS AREA WHICH LATEST SPC MESOANALYSIS SHOWS AS AN AXIS OF 1500 J/KG UNCAPPED MLCAPE. DEEP LAYER SHEAR IS MARGINAL AT THE MOMENT WITH ABOUT 30 KTS...BUT THIS NUMBER MAY INCREASE AS WE HEAD INTO THE LATE AFTERNOON AND EARLY EVENING AS MID LEVEL DISTURBANCE CURRENTLY OVER NORTH CENTRAL IOWA APPROACHES. THIS FEATURE WILL ALSO INCREASE THE BROAD SCALE ASCENT OVER THE AREA AND SHOULD LEAD TO AN INCREASE IN THUNDERSTORM COVERAGE AS WELL AS ORGANIZATION. THERE IS CERTAINLY AN INCREASED CONCERN FOR SEVERE WEATHER WHICH WILL HAVE TO BE MONITORED OVER THE NEXT SEVERAL HOURS...ESPECIALLY AS WE GET A LITTLE BETTER MID LEVEL LAPSE RATES OVER THE AREA AND THE AFOREMENTIONED SHEAR. THE FOCUS SHOULD SHIFT SOUTH THROUGH THE EVENING. THERE WILL SOME TRAINING ALONG THE BOUNDARY AS IT SAGS SOUTH THIS EVENING LEADING TO LOCALIZED HEAVY RAIN AMOUNTS...THOUGH LATEST GUIDANCE HAS SHIFTED THE FOCUS OF THE LOW LEVEL JET FARTHER EAST OF US OVERNIGHT...SO APPEARS FOR NOW THAT THE THREAT FOR HEAVY RAIN OVERNIGHT WILL ALSO BE FARTHER EAST. SATURDAY THROUGH MONDAY... SURFACE HIGH WILL BUILD SOUTHEAST FROM THE CANADIAN PRAIRIES...OVER LAKE MICHIGAN SUNDAY...THEN EAST TO THE MID APPALACHIAN RANGE MONDAY AND SHOULD PROVIDE A RELATIVELY BENIGN PERIOD OF WEATHER. WE DO GET A GLANCING BLOW OF COOLER H85 AIR WHICH BOTTOMS OUT 8-9C ON SUNDAY OVER NORTHEAST PORTIONS OF THE CWA. CANNOT COMPLETELY RULE OUT SOME DIURNALLY DRIVEN AFTERNOON SHOWERS...AND MODELS DO HINT AT SEVERAL WEAK SHORTWAVE TROUGHS RIDING DOWN THE RIDGE....BUT SEEMS MORE LIKELY THAT SUBSIDENCE ASSOCIATED WITH MODERATE MID LEVEL HEIGHT RISES FROM THE H5 RIDGE BUILDING ACROSS THE AREA WILL LIMIT CU GROWTH. NAM AND GFS SOUNDINGS BOTH INDICATE A SUBSIDENCE INVERSION SETTING UP AROUND 750 MB THROUGH THE WEEKEND WHICH WILL LIMIT THE DEPTH OF THE VERTICAL GROWTH AND SHOULD KEEP THE AREA DRY. THIS PERIOD WILL SEE TEMPERATURES WELL BELOW SEASONAL NORMS. AS MENTIONED...H85 TEMPS BOTTOM OUT SUNDAY AND UPPER AIR CLIMATOLOGY SHOWS THAT 75% OF THE TIME SURFACE TEMPS TOP OUT AT 76 OR COOLER WITH H85 TEMPS LESS THAN AROUND 9C. THE ECMWF/GEM/GFS ALL SUPPORT TEMPS IN THE 71-73 FOR CHICAGO AND 73-74 FOR ROCKFORD...THOUGH THE NAM WITH ITS TYPICAL HIGH BIAS IS SEVERAL DEGREES WARMER. GIVEN THAT EVEN MOS GUIDANCE IS CALLING FOR MID 70S...AND WE SHOULD CLOUD UP SOME WITH COLD AIR CU GROWTH...FELT COMFORTABLE DROPPING TEMPS A COUPLE MORE DEGREES SUNDAY...CLOSER TO THE BLEND OF RAW GUIDANCE. TUESDAY AND WEDNESDAY... WITH THE HIGH SHIFTING EAST OF THE AREA...AND LOW PRESSURE DEEPENING ACROSS THE CENTRAL/NORTHERN PLAINS...RETURN FLOW INTO THE MID MISSOURI AND MID MISSISSIPPI VALLEYS SHOULD ALLOW UPPER 60 TO LOW 70 DEWPOINTS TO OVERSPREAD THE AREA WITH MODERATE TO STRONG INSTABILITY DEVELOPING. STRONG WESTERLIES ALOFT COULD SET THE STAGE FOR A SEVERE WEATHER OUTBREAK SOMEWHERE NEARBY WITH CURRENT MODEL SOLUTIONS SETTING THE STAGE JUST TO OUR WEST. WHILE IT`S DIFFICULT TO PIN DOWN A SEVERE WEATHER THREAT THIS FAR OUT...MODELS ARE IN DECENT AGREEMENT AND WILL HAVE TO WATCH TUESDAY AND WEDNESDAY CLOSELY. TEMPERATURES SHOULD RETURN TO SEASONABLE...AND IF ANYTHING CURRENT PROJECTIONS OF LOW 80S MAY BE A BIT TOO COOL. A COLD FRONT IS PROJECTED TO PUSH OVER THE AREA WEDNESDAY NIGHT. THURSDAY AND FRIDAY... MODELS DIVERGE QUITE A BIT ON HOW FAR SOUTH TO PUSH THE FRONTAL BOUNDARY. THE GFS PUSHES THE FRONT WAY SOUTH INTO THE SOUTHEASTERN STATES BY FRIDAY WHILE THE ECMWF STALLS THE FRONT OUT INTO SOUTHERN ILLINOIS WITH PRECIPITATION OVERRUNNING THE BOUNDARY INTO THE SOUTHERN CWA. WHILE THE NORTH HALF OF THE CWA SHOULD BE DRY EITHER WAY...SOUTH OF I-80 ITS LESS CERTAIN. GIVEN THAT THE GFS ENSEMBLE MAINTAINS SOME QPF FARTHER NORTH THAN THE OPERATIONAL RUN...WILL MAINTAIN SOME CHANCE FOR THUNDERSTORMS ACROSS THE SOUTHERN CWA LATE IN THE WEEK. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * NORTH WINDS BECOMING NORTHEAST AROUND 10 KT BY MID TO LATE MORNING. //DISCUSSION...UPDATED 06Z... A COOL FRONT ACROSS NORTHERN ILLINOIS CONTINUES TO MOVE SOUTH EARLY THIS MORNING BRINGING NORTHERLY FLOW ACROSS THE TAF SITES. THIS WILL GRADUALLY SCOUR OUT THE LOW-LEVEL MOISTURE BY DAYBREAK. THE SURFACE HIGH PRESSURE RIDGE WILL BUILD IN FROM THE NORTHERN PLAINS THROUGH NORTH CENTRAL IL TODAY. SUCH AN ORIENTATION WILL ALLOW FOR NORTHERLY WINDS TO TURN MORE NORTHEAST DURING THE MORNING. THE LAKE INFLUENCE WILL ADD TO THAT NORTHEAST COMPONENT FOR ORD AND MDW AND MIXING SHOULD ALLOW FOR 10 KT SUSTAINED SPEEDS FOR MUCH OF THE AFTERNOON AND LIKELY AS EARLY AS LATE MORNING. A SECONDARY FRONT WILL DROP SOUTH THIS EVE BUT LOSS OF MIXING SHOULD KEEP SPEEDS PRIMARILY BELOW 10 KT BY 01Z-02Z OR SO...ALTHOUGH THE FRONT SHOULD HELP TO KEEP THE NNE DIRECTION. BESIDES SOME FEW- SCT CUMULUS AND CIRRUS TODAY NOT MUCH OF IMPACT EXPECTED CLOUD- WISE. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN OVERALL WIND TRENDS AND TIMING OF NE WINDS REACHING 10+KT TODAY. //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY THROUGH THURSDAY...MAINLY VFR. CHANCE OF TSRA LATE MONDAY INTO WEDNESDAY. MTF/RATZER && .MARINE... 232 PM CDT THUNDERSTORMS WILL PRIMARILY REMAIN OVER THE FAR SOUTHERN END OF THE LAKE THIS AFTERNOON AND THE STRONGER STORMS MAY PRODUCE GALE FORCE GUSTS. SOUTHWEST WINDS WILL BECOME NORTH TONIGHT BEHIND A COOL FRONT...AND NORTH/NORTHWEST WINDS ARE EXPECTED ACROSS THE LAKE THROUGH SUNDAY. HIGH PRESSURE MOVES OVER THE LAKE SATURDAY...AND WINDS BECOME SOUTHEAST BY MONDAY MORNING. THE HIGH SHIFTS EAST OF THE LAKE MONDAY AND ANOTHER LOW IS EXPECTED TO PASS NORTH OF THE LAKE THROUGH ONTARIO MID NEXT WEEK. GUIDANCE STILL FEATURES DIFFERENCES ON TIMING OF THE LOW...BUT TUESDAY NIGHT OR WEDNESDAY LOOKS LIKE THE BEST TIME FRAME. GUIDANCE ALSO SUGGESTS ANOTHER LOW MOVES IN FROM THE SOUTHWEST NEXT THURSDAY. JEE && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1109 PM CDT Fri Aug 2 2013 .DISCUSSION... ISSUED 830 PM CDT Fri Aug 2 2013 Latest surface analysis indicating the cold front pressing south through north central Illinois this evening...just north of our forecast area. Scattered showers and thunderstorms were occurring just ahead of the boundary this evening and the activity was shifting east and southeast...which should encompass at least our northeast third of the forecast area this evening into the overnight hours. Short term models suggest the showers will gradually decrease in coverage later this evening as the front shifts further south. Instability not that great with MUCAPEs of 500-1000 j/kg early this evening with the greater instability much further to our southwest, over parts of southern Missouri into SE Kansas. Front should be in close to the I-70 corridor by 12z Saturday, thus the higher rain chances tomorrow will be across the southeast. Have already updated the zones earlier this evening, so other than some adjustments to the sky grids and hourly temperatures in the grids, no other changes will be needed that would warrant another ZFP update. && .AVIATION... ISSUED 1105 PM CDT Fri Aug 2 2013 Main forecast concern this period will be with coverage of showers and thunderstorms along southward moving cold front which was now just north of galesburg and henry...but starting to make a bit more headway thanks to the convection. areas that do see the showers and isolated thunderstorms may experience brief mvfr conditions with some of the heavier rainfall, but as it looks now, those areas will be few and far between. Other concern will be with some lower cigs immediately behind the cold front but based on satellite and surface observations, not much showing up as of yet. Areas that did see some rainfall this evening may see some patchy mvfr vsbys in fog but any lower cloud cover or fog will quickly depart by 13z with VFR conditions prevailing for the remainder of the period. winds will be light southwest ahead of the cold front, and then turn light northerly behind it late tonight, and then turn into the northeast at 10 to 15 kts on Sat. SMITH && .PREV DISCUSSION... Issued 248 PM CDT Fri Aug 2 2013 Early afternoon surface map showing the cold front had crossed much of Wisconsin, then extended westward across southern Iowa to along the Kansas/Nebraska border. Precipitation so far has been pretty sparse across the area, with just some high-based very light showers tracking just south of the I-72 corridor. Subsidence in the wake of morning convection in northern Illinois actually allowed for a good deal of clearing across southeast Iowa and northern Illinois, although diurnal cumulus has been filling in rather quickly the last couple hours. The clearing helped to get the air more unstable, with CAPE`s of around 2000 J/kg across the northern third of the state with little cap, as evidenced by scattered storms forming around 2 pm just ahead of the front from Moline to Chicago. The primary forecast concern in the short term is with the convective chances over the next 18-24 hours. Rain chances in the longer range are also a concern due to MCS potential through the first half of next week. SHORT TERM...Tonight through Sunday... Morning model runs have significantly struggled with the convective trends thus far, so confidence in this part of the forecast is lower than normal. The most recent HRRR model appears to be closest to reality, and shows that the broken line of showers and storms to our north will be drifting across areas along and north of I-74 into the evening. Scattered storms currently in Missouri should track eastward as well, affecting the remainder of the forecast area. Precipitable water values of 1.75 to 2 inches should help produce some heavy rain with the stronger storms. Can`t rule out some gusty winds and hail as well, but wind shear overall is rather weak in our area and anything that does approach severe levels should be the pulse type. Overnight, the NAM and GFS already have the precipitation on the wane with a faster push to the cold front, while the ECMWF and Canadian models linger the showers/storms most of the night with a slower frontal passage. Have gone with the highest PoPs in the evening, but kept healthy chances over most of the area overnight. Not too many changes needed for Saturday, as the frontal boundary should be through most of the area by midday. Have kept the northwest CWA dry all day, and continued with all areas north of I-72 dry by afternoon. All precipitation should be out of the area by early evening, as high pressure builds southeast into the Midwest, and cooler/less humid air can be expected the rest of the weekend. LONG TERM...Monday through Friday... Upper level pattern looking fairly agreeable among the GFS and ECMWF models, with initial northwest flow flattening as a strong cutoff low sinks southward across Manitoba. GFS remains stronger with the high keeping our area dry into Monday, while the ECMWF keeps us on the periphery of the MCS track across Missouri. Have limited any PoPs to the far southwest for Sunday night and even then just kept them at 20 percent. Next shortwave on Tuesday should help boot the high eastward, but convection along the Gulf Coast will help rob some of the return moisture advection for a time, so have held off on any decent rain chances until Tuesday night. Getting into midweek, a surface boundary will become quasi- stationary as it becomes parallel to the upper flow. The model differences widen at this point, with the GFS pushing the boundary through us by late Wednesday night and the ECMWF keeping it north of the area until Thursday evening. The ultimate position and associated convective chances will come down to timing of fast moving shortwaves between the upper low and a sprawling upper high over the southern U.S. For now have favored a bit of a more southern push with a period of drier conditions Wednesday night and Thursday with increasing PoPs again after that. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1256 AM EDT SAT AUG 3 2013 .SYNOPSIS... ISSUED AT 351 PM EDT FRI AUG 2 2013 A PAIR OF UPPER LEVEL DISTURBANCES WILL COMBINE WITH A COLD FRONTAL BOUNDARY TO PRODUCE SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE REGION TONIGHT INTO EARLY SATURDAY. THE BELOW NORMAL TEMPERATURES WILL CONTINUE SUNDAY AND MONDAY BEHIND THIS FRONT WITH MAINLY DRY CONDITIONS. A WARM FRONT WILL APPROACH THE AREA TUESDAY BRINGING THE NEXT CHANCE OF SHOWERS AND THUNDERSTORMS. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 351 PM EDT FRI AUG 2 2013 PRIMARY SHORT TERM FORECAST CONCERN WILL BE ON CONVECTIVE POTENTIAL TONIGHT INTO EARLY SATURDAY. SHOWERS AND EMBEDDED THUNDERSTORMS HAVE SHIFTED EAST OF THE FORECAST AREA THIS AFTERNOON AS ISENTROPIC UPGLIDE HAS WEAKENED THROUGH THE DAY AND SHIFTED NORTH AND EAST OF LOCAL AREA. WATER VAPOR IMAGERY AT 18Z INDICATING A COUPLE OF SHORT WAVES OF INTEREST FOR TONIGHT/EARLY SATURDAY. THE FIRST OF THESE SHORT WAVES CONTINUES TO DIG ACROSS THE ARROWHEAD OF MINNESOTA ACROSS NORTHERN WISCONSIN. ANOTHER SMALLER SCALE WAVE APPEARS TO BE KICKING OUT OF EASTERN NEBRASKA...WITH SOME PRONOUNCED VEERING MID/UPPER LEVEL FLOW PER MERRIMAN PROFILER DATA PAST HOUR BEHIND THIS SHORT WAVE. A 120 KNOT UPPER JET STREAK DIGGING THROUGH BASE OF NORTHERN GREAT LAKES UPPER TROUGH WILL PLACE LOCAL AREA INCREASINGLY IN MORE FAVORED RIGHT ENTRANCE REGION BY LATE EVENING. VISIBLE SATELLITE IMAGERY TRENDS OVER PAST SEVERAL HOURS HAVE BEEN TOWARD BUILDING CU ALONG PREFRONTAL TROUGH TYPE FEATURE FROM THE QUAD CITIES INTO NORTHEAST ILLINOIS WHERE SFC DEW POINTS HAVE POOLED INTO THE UPPER 60S TO AROUND 70. ABOVE MID/UPPER LEVEL FORCING MECHANISMS SHOULD INTERACT WITH NARROW PREFRONTAL TROUGH TYPE FEATURE TO INCREASE COVERAGE OF SCATTERED SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON ACROSS NORTHEAST ILLINOIS...AND EVENTUALLY INTO NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN AS LARGER SCALE FRONTAL RESPONSE SHIFTS INTO THE AREA. RAP INITIALIZATION DATA DOES INDICATE THE RELATIVE STABLE BUBBLE ACROSS NORTHERN INDIANA GIVING WAY TO AXIS OF 100 HPA MLCAPES ON THE ORDER OF 1000 J/KG LATE THIS AFTERNOON. BASED ON HOW CURRENT SCENARIO SEEMS TO BE UNFOLDING...HAVE NOT MADE MANY CHANGES TO SCT POPS TRANSITIONING TO LIKELY POPS EARLY THIS EVENING ESPECIALLY SOUTHERN HALF AS FRONTAL CIRCULATION BEGINS TO MATURE. EXPECTING SCATTERED CONVECTION TO GENERALLY MERGE INTO LARGER AREA OF RAIN AND EMBEDDED THUNDERSTORMS AS THIS OCCURS. SOME DECENT RAINFALL AMOUNTS POSSIBLE ESPECIALLY SOUTHERN HALF GIVEN MOISTURE POOLING ALONG THE FRONT AND INCREASING FRONTOGENETIC RESPONSE LATER THIS EVENING. A FEW STRONGER CELLS ARE POSSIBLE LATE AFTERNOON/EARLY EVENING THROUGH ABOUT 00Z ACROSS ESPECIALLY WESTERN HALF GIVEN FAIRLY ROBUST DEEP LAYER SHEAR...BUT OVERALL SEVERE THREAT SHOULD REMAIN ISOLATED DUE TO MARGINAL INSTABILITY PROFILES. GENERALLY UTILIZED SREF IDEA FOR TIMING FRONTAL PROGRESSION INTO SATURDAY MORNING WHICH LARGELY SUPPORTS GOING FORECAST SO NO SIGNIFICANT CHANGES MADE TO SATURDAY POPS WITH BULK OF PRECIP SHIFTING SOUTH OF THE AREA LATE MORNING. && .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 351 PM EDT FRI AUG 2 2013 BRIEF RETURN TO TRANQUIL WEATHER EXPECTED FOR EARLY NEXT WEEK. SHORTWAVE RIDGING/SUBTLE MIDLEVEL HEIGHT RISES AND ANTICYCLONIC LOW LEVEL FLOW WILL BRING DRY CONDITIONS BEGINNING SATURDAY NIGHT AS THE COLD FRONT EXITS OUR AREA. LIGHT NORTHERLY WINDS/CAA AND DECREASING CLOUDS SHOULD ALLOW FOR A COOL NIGHT WITH LOWS DROPPING INTO THE LOW TO MID 50S PER CONSENSUS OF LATEST RAW AND STATISTICAL GUIDANCE. STRONG NEGATIVE THETA-E ADVECTION WILL LEAD TO MOSTLY SUNNY SKIES ON SUNDAY WITH JUST ENOUGH BOUNDARY LAYER MOISTURE SEEN IN FORECAST SOUNDINGS TO SUPPORT A FEW DIURNAL CU. 850MB TEMPS ALSO DROP INTO THE SINGLE DIGITS BUT AMPLE SUN SHOULD PUSH AFTERNOON TEMPS INTO THE MID 70S FOR MOST LOCATIONS. SURFACE HIGH WILL DRIFT OVERHEAD BY SUNDAY NIGHT WITH ANOTHER COOL NIGHT IN THE LOW 50S EXPECTED. A FEW AREAS IN OUR NORTHEAST MAY EVEN TOUCH UPPER 40S IF MIDLEVEL CLOUDS HOLD OFF LONG ENOUGH. SLIGHT MODERATION OF CANADIAN AIRMASS WILL ALLOW TEMPS ON MONDAY TO CLIMB A DEGREE OR TWO HIGHER BUT STILL ONLY MID TO UPPER 70S AT BEST. BY THE MIDDLE OF NEXT WEEK A PIECE OF ENERGY IS EXPECTED TO BREAK OFF THE POLAR VORTEX AND PHASE WITH THE PERSISTENT HUDSON BAY CLOSED LOW...ESTABLISHING A DEEP PV ANOMALY THAT IS EXPECTED TO MEANDER ACROSS SOUTHERN CANADA FOR MUCH OF NEXT WEEK. MEANWHILE...SEVERAL WEAK SHORTWAVES EMANATING FROM THE NORTHWEST CONUS TROUGH WILL BE SHEARED ACROSS THE GREAT LAKES IN FAST WNW FLOW ALOFT ON THE SOUTH SIDE OF AFOREMENTIONED ANOMALY. RETURN FLOW ON THE BACKSIDE OF DEPARTING SURFACE HIGH WILL ALSO BEGIN TO ADVECT A SLIGHTLY WARMER AND MORE MOIST/UNSTABLE AIRMASS BACK INTO THE REGION DURING THIS TIME. NEEDLESS TO SAY NUMERICAL GUIDANCE IS STRUGGLING WITH THE EVOLUTION OF THIS PATTERN. LATEST 12Z GFS IS CONTINUING TO TREND TOWARD THE MORE CONSISTENT ECMWF IN SHOWING THE BEST PRECIP POTENTIAL HOLDING OFF UNTIL LATE TUESDAY AND INTO WEDNESDAY BUT CONTINUES TO SHOW SIGNIFICANT DIFFERENCES BY LATE IN THE WEEK. CERTAINLY COULD BE A FEW SCATTERED SHOWERS FROM WAA/ISENTROPIC ASCENT ON TUESDAY BUT WILL HIGHLIGHT WEDNESDAY WITH THE HIGHEST POPS AS THE MAIN SHORTWAVE/COLD FRONT PUSH THROUGH THE REGION. WILL LEAVE THE END OF THE WEEK DRY FOR NOW UNTIL THE MODELS GET A BETTER HANDLE ON EVOLUTION OF DEEP CANADIAN VORTEX. SLIGHTLY WARMER TEMPS EXPECTED NEXT WEEK IN SOUTHWEST FLOW AHEAD OF FRONT BUT STILL HOVERING NEAR TO EVEN SLIGHTLY BELOW NORMAL FOR EARLY AUGUST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1255 AM EDT SAT AUG 3 2013 COLD FRONT WILL SLIDE SOUTHEAST THROUGH SBN BY 9-10Z AND FWA AROUND 11-12Z. SHOWERS...MORE WIDESPREAD AT FWA...CAN BE EXPECTED BEFORE THE FRONTAL PASSAGE AS WELL PRONOUNCED MID LEVEL SHORTWAVE DROPS THROUGH THE AREA IN NW FLOW ALOFT. FLIGHT CONDITIONS AT FWA WILL LIKELY OSCILLATE BTW IFR/MVFR AHEAD/ALONG OF THE FRONT...MAINLY MVFR/VFR AT SBN. POST FRONTAL ADVECTION OF DRIER NEAR SFC AIR WILL BE SOMEWHAT DELAYED WHICH MAY RESULT IN SLOWER EROSION OF BR/CIGS AT MAINLY FWA. THEREAFTER (DAYBREAK AT SBN AND MID MORNING FWA)... WEAK DRY/COOL ADVECTION IN DEVELOPING NORTHERLY FLOW WILL RESULT IN VFR CONDITIONS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...MARSILI SHORT TERM...MARSILI LONG TERM...AGD AVIATION...STEINWEDEL VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS WICHITA KS
938 PM CDT SUN AUG 4 2013 .MESOSCALE DISCUSSION... ISSUED AT 938 PM CDT SUN AUG 4 2013 SCATTERED CONVECTION HAS DEVELOPED AS LATE EVENING APPROACHES ACROSS SOUTH CENTRAL AND SOUTHEAST KANSAS. THIS IS A FAVORED LOCATION FOR THE NEXT SEVERAL HOURS...IF NOT THROUGH MUCH OF THE NIGHT...WHERE HEAVY RAINFALL PARAMETERS ARE MAXIMIZED SUCH AS DEEP MOISTURE CONVERGENCE...PRECIPITABLE WATER AND 850MB MOISTURE TRANSPORT. THE RUC SUGGESTS THIS SHOULD SHIFT PRIMARILY ACROSS THE SOUTHEAST PART OF KANSAS LATER IN THE NIGHT. KED && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 300 PM CDT SUN AUG 4 2013 MCV OVER THE FLINT HILLS THIS AFTERNOON WILL PUSH THROUGH SOUTHEAST KS INTO EARLY THIS EVENING. AREA OF SHOWERS/T-STORMS ASSOCIATED WITH THIS FEATURE HAS SHOWN A DIMINISHING TREND. A DEVELOPING 40 KT SOUTHWESTERLY LOW-LEVEL JET TONIGHT WILL RESULT IN MOISTURE TRANSPORT/ISENTROPIC LIFT ACROSS MUCH OF THE FORECAST AREA. THIS COULD RESULT IN A FEW CLUSTERS OF THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL RATES ESPECIALLY IN EAST-CENTRAL/SOUTHEAST KS. THEREFORE EXTENDED THE FLOOD WATCH INTO MONDAY MORNING FOR MANY COUNTIES IN CENTRAL/SOUTH CENTRAL/SOUTHEAST KS...ALTHOUGH NOT EXPECTING NEAR THE MAGNITUDE/EXTENT OF HEAVY RAIN/FLOODING THAT WE EXPERIENCED OVERNIGHT INTO TODAY. FORECAST CONFIDENCE IS ALSO LOWER THAN IT WAS FOR THE SIGNIFICANT HEAVY RAIN/FLOOD EVENT WHICH OCCURRED LAST NIGHT INTO THIS MORNING. REMNANT FRONTAL BOUNDARY PROGGED BY GFS/NAM-WRF TO LIFT NORTHWARD INTO CENTRAL/SOUTHEAST KS BY MONDAY PM. MOISTURE POOLING/CONVERGENCE INTO THE FRONTAL ZONE COULD LEAD TO WIDELY SCATTERED STORMS LATE IN THE AFTERNOON ALTHOUGH MID-LEVEL TEMPERATURES ARE EXPECTED TO CLIMB A FEW DEGREES PROVIDING A CAPPING CONCERN. WILL KEEP POPS LOW. BEST CHANCES FOR STORMS MON NIGHT WILL BE NEAR/NORTH OF FRONT IN CENTRAL/SOUTHEAST KS. NEXT CHANCE FOR POTENTIALLY MORE WIDESPREAD THUNDERSTORMS WITH HEAVY RAINFALL COULD COME LATER TUES NIGHT INTO WED NIGHT AS A COLD FRONT SURGES SOUTH INTO THE AREA. THE MODELS HINT THAT WEAK DISTURBANCES RIDING AROUND THE PERIPHERY OF THE SUBTROPICAL RIDGE MAY EJECT OUT ACROSS KS DURING THIS TIME PERIOD. VERY WARM AND HUMID CONDITIONS EXPECTED MONDAY-TUESDAY WITH WARMEST READINGS NEAR THE OKLAHOMA BORDER IN SOUTH CENTRAL KS. CURTAILED HIGHS A FEW DEGREES BELOW GUIDANCE ELSEWHERE WHERE WIDESPREAD SOAKING RAINS HAVE OCCURRED RECENTLY. HEAT INDICES WILL FLIRT WITH ADVISORY CRITERIA IN THE SOUTH BOTH MONDAY/TUESDAY AFTERNOON. JMC .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 300 PM CDT SUN AUG 4 2013 SUBTROPICAL UPPER HIGH REBUILDS OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY DURING THE PERIOD. WITH SUBTROPICAL MID-HIGH LEVEL MOIST PLUME WRAPPING AROUND THE HIGH WITH EMBEDDED WEAK PERTURBATIONS...WILL MAINTAIN AT LEAST SMALL CHANCES FOR THUNDERSTORMS DURING THIS EXTENDED PERIOD. THE PERTURBATIONS WILL BE DIFFICULT TO TIME THIS FAR OUT...SO HARD TO PINPOINT THE EXACT TIME PERIODS IT MAY RAIN. TEMPERATURES WILL MODERATE SLOWLY DURING THE PERIOD...BUT REMAINING BELOW SEASONAL AVERAGES. JMC && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 620 PM CDT SUN AUG 4 2013 AREAS OF MVFR CIGS WILL PLAGUE THE TERMINALS THROUGH MONDAY MORNING...WITH ANY SHOWERS AND STORMS EXPECTED TO BE MORE WIDELY SCATTERED OVERNIGHT. A VERY MOIST BOUNDARY LAYER AND LIGHT EASTERLY COMPONENT FLOW MAY PROMOTE LOWER STRATUS CIGS TO IFR CATEGORY EARLY MONDAY MORNING AND SOME FOG. FOR NOW THE HIGHER CONFIDENCE ON THIS OCCURRING WAS ACROSS THE HIGHER TERRAIN OF CENTRAL KANSAS AND THE KRSL TERMINAL. KED && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 72 95 73 96 / 40 40 40 10 HUTCHINSON 70 93 72 95 / 40 40 40 20 NEWTON 69 92 72 93 / 50 50 50 20 ELDORADO 71 92 72 93 / 60 60 50 10 WINFIELD-KWLD 73 96 73 97 / 60 60 30 10 RUSSELL 69 91 71 93 / 20 30 60 30 GREAT BEND 69 91 71 93 / 30 30 50 20 SALINA 70 91 72 93 / 40 40 50 20 MCPHERSON 70 93 72 94 / 40 40 50 20 COFFEYVILLE 73 95 74 96 / 60 60 40 10 CHANUTE 71 91 72 93 / 70 70 50 20 IOLA 71 90 72 91 / 70 70 50 20 PARSONS-KPPF 72 92 72 94 / 60 60 40 10 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH MONDAY MORNING FOR KSZ048>053-067>072-083- 092>096-098>100. && $$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1157 PM CDT Fri Aug 2 2013 .UPDATE... ISSUED AT 1157 PM CDT FRI AUG 2 2013 The aviation section has been updated for the 06Z TAF issuance. && .SHORT TERM...(This Evening through Sunday night) ISSUED AT 204 PM CDT FRI AUG 2 2013 A mid level wave was seen on satellite and via radar moving across west Missouri. Convection has formed with this wave and was moving east. Question is, how far east will it travel over the next several hours, as it encounters drier air across the region. Will gradually increase pops through the night. None of the models seem to have a good handle on convective trends. The latest RAP model is probably closest. Given low confidence in the latest solutions, will not stray too far from persistence. Even after a morning chance of convection, the probability for more development will persist as a frontal boundary sags south through the area late. Then, will decrease PoPs from north to south Saturday night and focus them over the west and south into Sunday and Sunday night. Temperatures will be a combination of the latest MAV/MET MOS and a blend of raw model output. .LONG TERM...(Monday through Friday) ISSUED AT 204 PM CDT FRI AUG 2 2013 For the beginning of the extended forecast period, namely Monday and Tuesday, there has been a little less confidence on the eastward extent of measurable PoP`s. During the last three days, attempted to highlight the southwestern part of the WFO PAH county warning area, namely southeast Missouri for rain chances. The low level surface winds/moisture convergence appears pinned to southeast Missouri through at least 12z (7am CDT) Tuesday. Although the SREF, GFS, and ECMWF model precipitation parametrization schemes vary, the low level frontal zones are similar during the aforementioned time period. Given the lack if identifiable and consistent vorticity advection above the frontal boundary, the decision was to limit the precipitation chances close to the boundary, plus or minus 50 nm. By late Tuesday night into Wednesday, the southern plains ridge builds northward, shifting and sharpening the baroclinic zone and frontal boundary further to the north. With this in mind, the higher rain chances are shifted into southern Illinois, southwest Indiana, and west Kentucky. This pattern remains intact through at least Wednesday afternoon, when the upper ridge begins to flatten and shift eastward across the lower Mississippi River valley. This subtle pattern change, combined with a sharper meridional gradient flow in the faster west to east flow, should lead to a much greater tightening of the frontal boundary through the WFO PAH forecast area next Thursday into Friday. Attempted to show a southward shift in focus of higher PoP`s into toward the Arkansas and Tennessee borders during this time period. It is also at this time that the highest PoPs in the extended forecast period should be expected in the WFO PAH forecast area. Tuesday through next Friday will likely see max/min temperatures approach or tie normals for this time of year, as the forecast area is fully enveloped in the warm sector. With variable cloud cover, heat index values should remain in check for most of next week. The only exception may be next Wednesday afternoon, when heat index values around 100 degrees may be possible along the southern border counties of southeast Missouri. && .AVIATION... ISSUED AT 1157PM CDT FRI AUG 2 2013 The best signal in the latest guidance keeps any significant convection west of the TAF sites through the overnight hours, and does not develop convection over the area during the day. Will therefore keep the forecast dry. The light rain over KOWB should move off to the east by the beginning of the period. Satellite imagery indicates that skies actually are beginning to clear over much of the area, especially at KCGI. Guidance does indicate more cloud cover over much of the area toward morning, but not necessarily over KCGI, so decided to throw in a TEMPO group for MVFR fog there toward sunrise. The other concern is the potential of MVFR ceilings developing through the day Saturday as the weak cold front tries to push through the region. See some currently to the north, closer to the front, so will add in a prevailing MVFR ceiling over most of the area beginning mid to late morning and continuing into the early afternoon. Figure that the ceilings will lift into VFR territory in the afternoon, but some guidance keeps the MVFR ceilings in through the afternoon and possibly into the evening, especially at KEVV and KOWB. Light south winds will veer to west as the front approaches in the morning, and then shift closer to due north behind the front by evening. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ UPDATE...DRS SHORT TERM...Noles LONG TERM...Smith AVIATION...DRS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
907 PM EDT SUN AUG 4 2013 .SYNOPSIS... DRY AND COOL WEATHER CAN BE EXPECTED FOR THE START OF THE WEEK AS HIGH PRESSURE SETTLES OVER THE OHIO VALLEY REGION. A RETURN TO HIGHER HUMIDITY AND NEAR-NORMAL TEMPERATURES CAN BE EXPECTED MID- WEEK BEFORE A COLD FRONT IMPACTS THE REGION LATE IN THE WEEK. && .NEAR TERM /THROUGH MONDAY/... WITH 9PM UPDATE...ADDED PATCHY FOG TO ALL LOCATIONS...AND ADDED AREAS OF FOG TO ALL VALLEY LOCATIONS. CURRENT DEWPOINTS ARE STILL HIGHER THAN PROJECTED OVERNIGHT LOWS...ESPECIALLY NORTH OF PITTSBURGH...AND WINDS ARE EXPECTED TO GO CALM AT MOST LOCATIONS TONIGHT. BOTH OF THESE FACTORS SHOULD ALLOW FOR SOME FOG DEVELOPMENT AT ALL LOCATIONS. USED RAP WINDS AND LAMP TEMPERATURES OVERNIGHT. PREVIOUS DISCUSSION FOLLOWS. WITH 515PM UPDATE...JUST MADE SOME MINOR TWEAKS TO HOURLY TEMPERATURES AND SKY COVER. REST OF FORECAST APPEARS ON TRACK. EXPANSIVE SFC HIPRES WILL AID IN DECRG BNDRY LYR MSTR TNGT AS WINDS DECOUPLE. CLRG SKY WILL PROMOTE RADIATIONAL COOLING OVNGT AND WILL SUPPORT FOG DVLPMT AT LEAST IN LOCATIONS THAT SAW FOG THIS MRNG. GIVEN DEG OF COOLING DEPICTED IN MODELS...IT WOULD NOT BE OUT OF THE QUESTION TO SEE DENSE FOG DVLP IN VLYS AGAIN. BUT RATE OF COOLING AND RATE OF DRYING WILL COMBAT EACH OTHER...AND IT IS UNCLEAR ATTM WHICH WILL WIN. NEVERTHELESS...IT APPEARS THE COOLEST MINIMA IN RECENT MEMORY CAN BE XPCD TNGT...UPR 40S-MID 50S. SHELTERED VLYS MAY APRCH LWR 40S. STRATOCU FIELD XPCD TO FORM ONCE AGAIN ON MON AMID AMPLE HEATING OF BNDRY LYR. SF HIPRES WILL MOVE EWD THRU THE DAY IN RESPONSE TO APRCHG LOW-AMPLITUDE SHRTWV TROF IN GRTLKS RGN. LGT SLY FLOW DVLPG IN WRN ZONES BY AFTN WILL AID IN MODEST INCR IN MSTR AND PSBLTY OF A SHWR OR TWO LATE IN THE DAY. MAXIMA GENLY IN THE MID-UPR 70S CAN BE XPCD. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... DP H5 LOW OVER N-CNTRL CANADA WILL MAINTAIN GENLY WLY FLOW ALOFT OVER THE NRN CONUS. SERIES OF SHRTWV TROFS IN THIS WLY FLOW WILL AID IN NWD TRANSPORT OF MSTR AS WMFNT BGNS ITS NEWD ADVC. SHWRS XPCD TO FORM IN MODEST WARM AIR ADVCTN PATTERN MON NGT ALONG WEAK SFC TROF. GREATER CVRG XPCD TUE AS WARM SECTOR OVERSPREADS THE RGN. ALTHOUGH DETAILS DIFFER AMONG NAM/GFS/ECMWF...ALL SUGGEST SGFNT CVRG OF PCPN ON WED AS POTENT SHRTWV TROF CROSSES THE GRTLKS RGN. GIVEN DEWPT RECOVERY INTO THE UPR 60S F AND NR-NRML TEMPS...THIS PSBLTY IS VERY REASONABLE. POPS WERE INCRD CONSIDERABLY WED AFTN AND EVE...GIVEN CLR MOS SIGNAL OF PCPN. CDFNT WILL APRCH FROM THE NW WED NGT BUT XPCD TO SLOW ITS ADVC THRU EARLY THU MRNG. AS A RESULT...MSTR AND CLD CVR WILL RMN ACRS FCST AREA AT LEAST THRU SHORT-TERM PD. BRIEF APPEARANCE OF NR-NRML TEMPS XPCD TUE-WED AS MSTR INCRS AND WARM SECTOR MATERIALIZES. MAXIMA IN THE UPR 70S-LWR 80S CAN BE XPCD DURG THIS TIME...WITH MINIMA IN THE LWR-UPR 60S. && .LONG TERM /THURSDAY THROUGH SUNDAY/... GFS AND ECMWF RMN IN GENL AGRMNT IN DVLPG A DEEP UPR LOW OVR MANITOBA BY MIDWEEK...THEN PR0JECTING IT TWD/ACRS JAMES BAY BY THE WEEKEND. EWD PROGRESS OF THE LOW WL SEND A CDFNT ACRS THE AREA...HENCE THE POP INCRS FOR THU...ALTHOUGH A DEEP MSTR SURGE IS NOT ANTICIPATED GIVEN THE ENTRENCHMENT OF A BROAD RIDGE OVR THE GULF COAST STATES. POST FRONTAL TEMPS WERE FORECAST CONSERVATIVELY...JUST A FEW DEGREES UNDR THE AVERAGES FOR NXT WEEKEND. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... VFR WILL PERSIST THROUGH THE EARLY NIGHT. CONDITIONS WILL DETERIORATE AT ALL TERMINALS TO IFR VIS AS FOG DEVELOPS DUE TO STRONG SUBSIDENCE BUILDING IN WAKE OF RECENT HIGH RELATIVE MOISTURE BOUNDARY LAYER. FOG SHOULD BURN OFF RAPIDLY AND TERMINALS WILL RETURN TO VFR AS DAYTIME HEATING BEGINS WITH THE RISING SUN. OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/... HIGH PRESSURE WILL MAINTAIN MOSTLY VFR CONDITIONS THROUGH TUESDAY. AN APPROACHING FRONT WILL CAUSE POSSIBLE PERIODS OF IFR FROM WEDNESDAY THROUGH FRIDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS DULUTH MN
1255 PM CDT SAT AUG 3 2013 .AVIATION...18Z TAF ISSUANCE. BUILDING HIGH PRESSURE FROM THE DAKOTAS WILL RESULT IN NORTHWEST WINDS...WITH OCCASIONAL GUSTS TO 20 KT...THROUGH THE AFTERNOON. VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD WITH SCT-BKN CU THIS AFTERNOON RANGING FROM 5-8 KFT. WINDS WILL BECOMING LIGHT WITH DECREASING CLOUDS AFTER 00Z. THE SFC RIDGE WILL MOVE INTO THE NORTHLAND OVERNIGHT...ALLOWING FOR STRONG RADIATIONAL COOLING AND A POTENTIAL FOR A FEW HOUR WINDOW OF PATCHY BR/FG. && .PREV DISCUSSION... /ISSUED 1136 AM CDT SAT AUG 3 2013/ UPDATE...LOOKS LIKE A PARTLY CLOUDY DAY ACROSS THE NORTHLAND WITH PARTLY CLOUDY CUMULUS FOR THE REST OF THE DAY. TEMPS WILL CONTINUE TO RISE INTO THE 70S FOR MOST AREAS WITH NORTHERLY WINDS. PREV DISCUSSION... /ISSUED 303 AM CDT SAT AUG 3 2013/ SHORT TERM.../THROUGH TONIGHT/ AT 300AM/0800Z...SURFACE HIGH PRESSURE WAS CENTERED OVER CENTRAL SASKATCHEWAN AND MANITOBA. THE AXIS OF A MID/UPPER LEVEL RIDGE STRETCHED ACROSS THE WESTERN PLAINS. A SHORTWAVE NEAR THE MONTANA/NORTH DAKOTA BORDER WAS MOVING EAST AS IT ROUNDED THE RIDGE...AND IT WAS BRINGING BKN/OVC MID/UPPER LEVEL CLOUDS ACROSS NORTH DAKOTA INTO NORTHERN MINNESOTA. A MID/UPPER LEVEL LOW WAS NEAR SW HUDSON BAY. BKN/OVC LOW CLOUDS COVERED MUCH OF NORTHERN ONTARIO...BUT WERE SLOWLY APPROACHING THE CANADA/MINNESOTA BORDER. MOST OF THE NORTHLAND HAD CLEAR SKIES EXCEPT FOR THE WESTERN FORECAST AREA DUE TO THE FEW/SCT MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE APPROACHING SHORTWAVE BEGINNING WORKING THEIR WAY INTO THE NORTHLAND. THE SURFACE WINDS WERE NEARLY CALM OR VERY LIGHT FROM THE WNW. TEMPERATURES RANGED FROM THE MID 40S TO LOW 50S. TODAY...THE CENTER OF THE SURFACE HIGH PRESSURE IN CANADA WILL MOVE INTO THE RED RIVER VALLEY REGION BY LATE THIS AFTERNOON. THE NORTHLAND CAN EXPECT PARTLY SUNNY SKIES. THERE WILL BE SOME MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE SHORTWAVE IN NORTH DAKOTA THAT WILL CUT ACROSS NORTHERN MINNESOTA THIS MORNING...AS WELL AS SCATTERED CUMULUS THAT WILL DEVELOP BY LATE THIS MORNING DUE TO THE LOW CONVECTIVE TEMPERATURES IN THE COOL NW FLOW. HIGH TEMPERATURES SHOULD RANGE FROM THE UPPER 60S TO MID 70S. TONIGHT...THE CENTER OF THE HIGH PRESSURE SYSTEM WILL MOVE THROUGH THE NORTHLAND. THIS WILL BRING CALM WINDS AND CLEAR SKIES TO THE REGION. THERE COULD BE PATCHY FOG...BUT SINCE THE SOUNDINGS AND MODEL FORECAST SURFACE CONDENSATION PRESSURE DEFICITS DO NOT PROVIDE ENOUGH SUGGESTION OF FOG...I LEFT IT OUT OF THE FORECAST AT THIS POINT. THE DAY SHIFT MAY NEED TO ADD PATCHY FOG TO THE FORECAST. OVERNIGHT LOWS SHOULD BE IN THE LOW TO UPPER 40S ACROSS MOST OF THE REGION. I WOULD NOT BE SURPRISED IF ISOLATED LOCATIONS ACROSS NORTHERN MINNESOTA GET INTO THE UPPER 30S. LONG TERM.../SUNDAY - FRIDAY/ THE AREA OF HIGH PRESSURE WILL BRING ANOTHER DAY OF QUIET CONDITIONS ACROSS THE REGION ON SUNDAY. THE NEXT SHOT OF PRECIPITATION WILL COME MONDAY THROUGH TUESDAY WHEN A LOW PRESSURE CENTER MOVES THROUGH SOUTHERN CANADA ALONG WITH A SHORTWAVE THAT MOVE THROUGH NRN MN MONDAY AND TUESDAY MORNING WHICH WILL BRING SHOWERS AND THUNDERSTORMS TO THE FORECAST AREA. THERE WILL BE BREAK TUESDAY MORNING BEFORE THE LOW DRAGS A FRONT THROUGH THE REGION TUESDAY AFTERNOON AND EVENING BRINGING ANOTHER CHANCE FOR THUNDERSTORMS. AFTER THE FRONT PASSES...COOLER THAN NORMAL TEMPS WILL FLOW INTO THE REGION FOR THE REST OF THE WEEK WITH LITTLE PRECIPITATION EXPECTED THROUGH THE PERIOD. AVIATION.../06Z TAF ISSUANCE/ MAINLY VFR CONDITIONS WILL OCCUR THROUGH THE PERIOD. THERE MAY BE SOME PATCHY FOG TONIGHT WITH VSBYS DROPPING TO IFR...AND WE HAVE THAT IN THE KBRD/KHIB/KHYR TAFS ATTM. BROKEN CEILINGS FROM 5-8KFT WILL BE POSSIBLE OVER THE ARROWHEAD AND BORDER REGION TONIGHT...BUT BOTH THE RAP AND NAM SUGGEST IT WILL BE MOSTLY SCATTERED BY LATE TONIGHT. WE EXPECT MORE SCATTERED TO BROKEN VFR CUMULUS TO FORM ON SATURDAY WITH SOME HEATING. && .POINT TEMPS/POPS... DLH 50 74 50 71 / 0 10 10 20 INL 42 72 49 73 / 0 10 10 10 BRD 49 75 57 74 / 0 10 30 30 HYR 44 73 52 72 / 0 10 10 30 ASX 47 74 51 70 / 0 10 10 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
1136 AM CDT SAT AUG 3 2013 .UPDATE...LOOKS LIKE A PARTLY CLOUDY DAY ACROSS THE NORTHLAND WITH PARTLY CLOUDY CUMULUS FOR THE REST OF THE DAY. TEMPS WILL CONTINUE TO RISE INTO THE 70S FOR MOST AREAS WITH NORTHERLY WINDS. && .PREV DISCUSSION... /ISSUED 653 AM CDT SAT AUG 3 2013/ AVIATION...12Z TAFS...LIFR-IFR CIGS/VSBYS IN FOG WILL IMPROVE TO VFR CONDTIONS BY MID-MORNING. ELSEWHERE...AN AREA OF HIGH PRESSURE WILL DOMINATE THE WEATHER THROUGH SUNDAY. VFR CONDTIONS WILL BE ALL ALL SITES THROUGH SUNDAY AFTERNOON. THERE MAY BE SOME MVFR VSBYS IN FOG AT SOME STIES EARLY SUNDAY MORNING. PREV DISCUSSION... /ISSUED 303 AM CDT SAT AUG 3 2013/ SHORT TERM.../THROUGH TONIGHT/ AT 300AM/0800Z...SURFACE HIGH PRESSURE WAS CENTERED OVER CENTRAL SASKATCHEWAN AND MANITOBA. THE AXIS OF A MID/UPPER LEVEL RIDGE STRETCHED ACROSS THE WESTERN PLAINS. A SHORTWAVE NEAR THE MONTANA/NORTH DAKOTA BORDER WAS MOVING EAST AS IT ROUNDED THE RIDGE...AND IT WAS BRINGING BKN/OVC MID/UPPER LEVEL CLOUDS ACROSS NORTH DAKOTA INTO NORTHERN MINNESOTA. A MID/UPPER LEVEL LOW WAS NEAR SW HUDSON BAY. BKN/OVC LOW CLOUDS COVERED MUCH OF NORTHERN ONTARIO...BUT WERE SLOWLY APPROACHING THE CANADA/MINNESOTA BORDER. MOST OF THE NORTHLAND HAD CLEAR SKIES EXCEPT FOR THE WESTERN FORECAST AREA DUE TO THE FEW/SCT MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE APPROACHING SHORTWAVE BEGINNING WORKING THEIR WAY INTO THE NORTHLAND. THE SURFACE WINDS WERE NEARLY CALM OR VERY LIGHT FROM THE WNW. TEMPERATURES RANGED FROM THE MID 40S TO LOW 50S. TODAY...THE CENTER OF THE SURFACE HIGH PRESSURE IN CANADA WILL MOVE INTO THE RED RIVER VALLEY REGION BY LATE THIS AFTERNOON. THE NORTHLAND CAN EXPECT PARTLY SUNNY SKIES. THERE WILL BE SOME MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE SHORTWAVE IN NORTH DAKOTA THAT WILL CUT ACROSS NORTHERN MINNESOTA THIS MORNING...AS WELL AS SCATTERED CUMULUS THAT WILL DEVELOP BY LATE THIS MORNING DUE TO THE LOW CONVECTIVE TEMPERATURES IN THE COOL NW FLOW. HIGH TEMPERATURES SHOULD RANGE FROM THE UPPER 60S TO MID 70S. TONIGHT...THE CENTER OF THE HIGH PRESSURE SYSTEM WILL MOVE THROUGH THE NORTHLAND. THIS WILL BRING CALM WINDS AND CLEAR SKIES TO THE REGION. THERE COULD BE PATCHY FOG...BUT SINCE THE SOUNDINGS AND MODEL FORECAST SURFACE CONDENSATION PRESSURE DEFICITS DO NOT PROVIDE ENOUGH SUGGESTION OF FOG...I LEFT IT OUT OF THE FORECAST AT THIS POINT. THE DAY SHIFT MAY NEED TO ADD PATCHY FOG TO THE FORECAST. OVERNIGHT LOWS SHOULD BE IN THE LOW TO UPPER 40S ACROSS MOST OF THE REGION. I WOULD NOT BE SURPRISED IF ISOLATED LOCATIONS ACROSS NORTHERN MINNESOTA GET INTO THE UPPER 30S. LONG TERM.../SUNDAY - FRIDAY/ THE AREA OF HIGH PRESSURE WILL BRING ANOTHER DAY OF QUIET CONDITIONS ACROSS THE REGION ON SUNDAY. THE NEXT SHOT OF PRECIPITATION WILL COME MONDAY THROUGH TUESDAY WHEN A LOW PRESSURE CENTER MOVES THROUGH SOUTHERN CANADA ALONG WITH A SHORTWAVE THAT MOVE THROUGH NRN MN MONDAY AND TUESDAY MORNING WHICH WILL BRING SHOWERS AND THUNDERSTORMS TO THE FORECAST AREA. THERE WILL BE BREAK TUESDAY MORNING BEFORE THE LOW DRAGS A FRONT THROUGH THE REGION TUESDAY AFTERNOON AND EVENING BRINGING ANOTHER CHANCE FOR THUNDERSTORMS. AFTER THE FRONT PASSES...COOLER THAN NORMAL TEMPS WILL FLOW INTO THE REGION FOR THE REST OF THE WEEK WITH LITTLE PRECIPITATION EXPECTED THROUGH THE PERIOD. AVIATION.../06Z TAF ISSUANCE/ MAINLY VFR CONDITIONS WILL OCCUR THROUGH THE PERIOD. THERE MAY BE SOME PATCHY FOG TONIGHT WITH VSBYS DROPPING TO IFR...AND WE HAVE THAT IN THE KBRD/KHIB/KHYR TAFS ATTM. BROKEN CEILINGS FROM 5-8KFT WILL BE POSSIBLE OVER THE ARROWHEAD AND BORDER REGION TONIGHT...BUT BOTH THE RAP AND NAM SUGGEST IT WILL BE MOSTLY SCATTERED BY LATE TONIGHT. WE EXPECT MORE SCATTERED TO BROKEN VFR CUMULUS TO FORM ON SATURDAY WITH SOME HEATING. && .POINT TEMPS/POPS... DLH 72 50 74 50 / 0 0 10 10 INL 69 42 72 49 / 0 0 10 10 BRD 74 49 75 57 / 0 0 10 30 HYR 73 44 73 52 / 0 0 10 10 ASX 73 47 74 51 / 0 0 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...DAP LONG TERM....GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
653 AM CDT SAT AUG 3 2013 .AVIATION...12Z TAFS...LIFR-IFR CIGS/VSBYS IN FOG WILL IMPROVE TO VFR CONDTIONS BY MID-MORNING. ELSEWHERE...AN AREA OF HIGH PRESSURE WILL DOMINATE THE WEATHER THROUGH SUNDAY. VFR CONDTIONS WILL BE ALL ALL SITES THROUGH SUNDAY AFTERNOON. THERE MAY BE SOME MVFR VSBYS IN FOG AT SOME STIES EARLY SUNDAY MORNING. && .PREV DISCUSSION... /ISSUED 303 AM CDT SAT AUG 3 2013/ SHORT TERM.../THROUGH TONIGHT/ AT 300AM/0800Z...SURFACE HIGH PRESSURE WAS CENTERED OVER CENTRAL SASKATCHEWAN AND MANITOBA. THE AXIS OF A MID/UPPER LEVEL RIDGE STRETCHED ACROSS THE WESTERN PLAINS. A SHORTWAVE NEAR THE MONTANA/NORTH DAKOTA BORDER WAS MOVING EAST AS IT ROUNDED THE RIDGE...AND IT WAS BRINGING BKN/OVC MID/UPPER LEVEL CLOUDS ACROSS NORTH DAKOTA INTO NORTHERN MINNESOTA. A MID/UPPER LEVEL LOW WAS NEAR SW HUDSON BAY. BKN/OVC LOW CLOUDS COVERED MUCH OF NORTHERN ONTARIO...BUT WERE SLOWLY APPROACHING THE CANADA/MINNESOTA BORDER. MOST OF THE NORTHLAND HAD CLEAR SKIES EXCEPT FOR THE WESTERN FORECAST AREA DUE TO THE FEW/SCT MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE APPROACHING SHORTWAVE BEGINNING WORKING THEIR WAY INTO THE NORTHLAND. THE SURFACE WINDS WERE NEARLY CALM OR VERY LIGHT FROM THE WNW. TEMPERATURES RANGED FROM THE MID 40S TO LOW 50S. TODAY...THE CENTER OF THE SURFACE HIGH PRESSURE IN CANADA WILL MOVE INTO THE RED RIVER VALLEY REGION BY LATE THIS AFTERNOON. THE NORTHLAND CAN EXPECT PARTLY SUNNY SKIES. THERE WILL BE SOME MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE SHORTWAVE IN NORTH DAKOTA THAT WILL CUT ACROSS NORTHERN MINNESOTA THIS MORNING...AS WELL AS SCATTERED CUMULUS THAT WILL DEVELOP BY LATE THIS MORNING DUE TO THE LOW CONVECTIVE TEMPERATURES IN THE COOL NW FLOW. HIGH TEMPERATURES SHOULD RANGE FROM THE UPPER 60S TO MID 70S. TONIGHT...THE CENTER OF THE HIGH PRESSURE SYSTEM WILL MOVE THROUGH THE NORTHLAND. THIS WILL BRING CALM WINDS AND CLEAR SKIES TO THE REGION. THERE COULD BE PATCHY FOG...BUT SINCE THE SOUNDINGS AND MODEL FORECAST SURFACE CONDENSATION PRESSURE DEFICITS DO NOT PROVIDE ENOUGH SUGGESTION OF FOG...I LEFT IT OUT OF THE FORECAST AT THIS POINT. THE DAY SHIFT MAY NEED TO ADD PATCHY FOG TO THE FORECAST. OVERNIGHT LOWS SHOULD BE IN THE LOW TO UPPER 40S ACROSS MOST OF THE REGION. I WOULD NOT BE SURPRISED IF ISOLATED LOCATIONS ACROSS NORTHERN MINNESOTA GET INTO THE UPPER 30S. LONG TERM.../SUNDAY - FRIDAY/ THE AREA OF HIGH PRESSURE WILL BRING ANOTHER DAY OF QUIET CONDITIONS ACROSS THE REGION ON SUNDAY. THE NEXT SHOT OF PRECIPITATION WILL COME MONDAY THROUGH TUESDAY WHEN A LOW PRESSURE CENTER MOVES THROUGH SOUTHERN CANADA ALONG WITH A SHORTWAVE THAT MOVE THROUGH NRN MN MONDAY AND TUESDAY MORNING WHICH WILL BRING SHOWERS AND THUNDERSTORMS TO THE FORECAST AREA. THERE WILL BE BREAK TUESDAY MORNING BEFORE THE LOW DRAGS A FRONT THROUGH THE REGION TUESDAY AFTERNOON AND EVENING BRINGING ANOTHER CHANCE FOR THUNDERSTORMS. AFTER THE FRONT PASSES...COOLER THAN NORMAL TEMPS WILL FLOW INTO THE REGION FOR THE REST OF THE WEEK WITH LITTLE PRECIPITATION EXPECTED THROUGH THE PERIOD. AVIATION.../06Z TAF ISSUANCE/ MAINLY VFR CONDITIONS WILL OCCUR THROUGH THE PERIOD. THERE MAY BE SOME PATCHY FOG TONIGHT WITH VSBYS DROPPING TO IFR...AND WE HAVE THAT IN THE KBRD/KHIB/KHYR TAFS ATTM. BROKEN CEILINGS FROM 5-8KFT WILL BE POSSIBLE OVER THE ARROWHEAD AND BORDER REGION TONIGHT...BUT BOTH THE RAP AND NAM SUGGEST IT WILL BE MOSTLY SCATTERED BY LATE TONIGHT. WE EXPECT MORE SCATTERED TO BROKEN VFR CUMULUS TO FORM ON SATURDAY WITH SOME HEATING. && .POINT TEMPS/POPS... DLH 72 50 74 50 / 0 0 10 10 INL 69 42 72 49 / 0 0 10 10 BRD 74 49 75 57 / 0 0 10 30 HYR 73 44 73 52 / 0 0 10 10 ASX 73 47 74 51 / 0 0 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...GROCHOCINSKI LONG TERM....STEWART AVIATION...STEWART
AREA FORECAST DISCUSSION
NWS DULUTH MN
303 AM CDT SAT AUG 3 2013 .SHORT TERM.../THROUGH TONIGHT/ AT 300AM/0800Z...SURFACE HIGH PRESSURE WAS CENTERED OVER CENTRAL SASKATCHEWAN AND MANITOBA. THE AXIS OF A MID/UPPER LEVEL RIDGE STRETCHED ACROSS THE WESTERN PLAINS. A SHORTWAVE NEAR THE MONTANA/NORTH DAKOTA BORDER WAS MOVING EAST AS IT ROUNDED THE RIDGE...AND IT WAS BRINGING BKN/OVC MID/UPPER LEVEL CLOUDS ACROSS NORTH DAKOTA INTO NORTHERN MINNESOTA. A MID/UPPER LEVEL LOW WAS NEAR SW HUDSON BAY. BKN/OVC LOW CLOUDS COVERED MUCH OF NORTHERN ONTARIO...BUT WERE SLOWLY APPROACHING THE CANADA/MINNESOTA BORDER. MOST OF THE NORTHLAND HAD CLEAR SKIES EXCEPT FOR THE WESTERN FORECAST AREA DUE TO THE FEW/SCT MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE APPROACHING SHORTWAVE BEGINNING WORKING THEIR WAY INTO THE NORTHLAND. THE SURFACE WINDS WERE NEARLY CALM OR VERY LIGHT FROM THE WNW. TEMPERATURES RANGED FROM THE MID 40S TO LOW 50S. TODAY...THE CENTER OF THE SURFACE HIGH PRESSURE IN CANADA WILL MOVE INTO THE RED RIVER VALLEY REGION BY LATE THIS AFTERNOON. THE NORTHLAND CAN EXPECT PARTLY SUNNY SKIES. THERE WILL BE SOME MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE SHORTWAVE IN NORTH DAKOTA THAT WILL CUT ACROSS NORTHERN MINNESOTA THIS MORNING...AS WELL AS SCATTERED CUMULUS THAT WILL DEVELOP BY LATE THIS MORNING DUE TO THE LOW CONVECTIVE TEMPERATURES IN THE COOL NW FLOW. HIGH TEMPERATURES SHOULD RANGE FROM THE UPPER 60S TO MID 70S. TONIGHT...THE CENTER OF THE HIGH PRESSURE SYSTEM WILL MOVE THROUGH THE NORTHLAND. THIS WILL BRING CALM WINDS AND CLEAR SKIES TO THE REGION. THERE COULD BE PATCHY FOG...BUT SINCE THE SOUNDINGS AND MODEL FORECAST SURFACE CONDENSATION PRESSURE DEFICITS DO NOT PROVIDE ENOUGH SUGGESTION OF FOG...I LEFT IT OUT OF THE FORECAST AT THIS POINT. THE DAY SHIFT MAY NEED TO ADD PATCHY FOG TO THE FORECAST. OVERNIGHT LOWS SHOULD BE IN THE LOW TO UPPER 40S ACROSS MOST OF THE REGION. I WOULD NOT BE SURPRISED IF ISOLATED LOCATIONS ACROSS NORTHERN MINNESOTA GET INTO THE UPPER 30S. .LONG TERM.../SUNDAY - FRIDAY/ THE AREA OF HIGH PRESSURE WILL BRING ANOTHER DAY OF QUIET CONDITIONS ACROSS THE REGION ON SUNDAY. THE NEXT SHOT OF PRECIPITATION WILL COME MONDAY THROUGH TUESDAY WHEN A LOW PRESSURE CENTER MOVES THROUGH SOUTHERN CANADA ALONG WITH A SHORTWAVE THAT MOVE THROUGH NRN MN MONDAY AND TUESDAY MORNING WHICH WILL BRING SHOWERS AND THUNDERSTORMS TO THE FORECAST AREA. THERE WILL BE BREAK TUESDAY MORNING BEFORE THE LOW DRAGS A FRONT THROUGH THE REGION TUESDAY AFTERNOON AND EVENING BRINGING ANOTHER CHANCE FOR THUNDERSTORMS. AFTER THE FRONT PASSES...COOLER THAN NORMAL TEMPS WILL FLOW INTO THE REGION FOR THE REST OF THE WEEK WITH LITTLE PRECIPITATION EXPECTED THROUGH THE PERIOD. && .AVIATION.../06Z TAF ISSUANCE/ MAINLY VFR CONDITIONS WILL OCCUR THROUGH THE PERIOD. THERE MAY BE SOME PATCHY FOG TONIGHT WITH VSBYS DROPPING TO IFR...AND WE HAVE THAT IN THE KBRD/KHIB/KHYR TAFS ATTM. BROKEN CEILINGS FROM 5-8KFT WILL BE POSSIBLE OVER THE ARROWHEAD AND BORDER REGION TONIGHT...BUT BOTH THE RAP AND NAM SUGGEST IT WILL BE MOSTLY SCATTERED BY LATE TONIGHT. WE EXPECT MORE SCATTERED TO BROKEN VFR CUMULUS TO FORM ON SATURDAY WITH SOME HEATING. && .POINT TEMPS/POPS... DLH 72 50 74 50 / 0 0 10 10 INL 69 42 72 49 / 0 0 10 10 BRD 74 49 75 57 / 0 0 10 30 HYR 73 44 73 52 / 0 0 10 10 ASX 73 47 74 51 / 0 0 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...GROCHOCINSKI LONG TERM....STEWART AVIATION...STEWART
AREA FORECAST DISCUSSION
NWS DULUTH MN
1242 AM CDT SAT AUG 3 2013 .AVIATION...MAINLY VFR CONDITIONS WILL OCCUR THROUGH THE PERIOD. THERE MAY BE SOME PATCHY FOG TONIGHT WITH VSBYS DROPPING TO IFR...AND WE HAVE THAT IN THE KBRD/KHIB/KHYR TAFS ATTM. BROKEN CEILINGS FROM 5-8KFT WILL BE POSSIBLE OVER THE ARROWHEAD AND BORDER REGION TONIGHT...BUT BOTH THE RAP AND NAM SUGGEST IT WILL BE MOSTLY SCATTERED BY LATE TONIGHT. WE EXPECT MORE SCATTERED TO BROKEN VFR CUMULUS TO FORM ON SATURDAY WITH SOME HEATING. && .PREV DISCUSSION... /ISSUED 635 PM CDT FRI AUG 2 2013/ UPDATE... AREA RADARS SHOW NO RETURNS OVER OUR CWA...WITH A FEW ECHOES THAT MAY SLIDE BETWEEN THE TIP OF THE ARROWHEAD AND THUNDER BAY OVER THE NEXT COUPLE HOURS. WE REMOVED POPS FROM THE ARROWHEAD THIS EVENING AND MADE SOME ADJUSTMENTS TO CLOUD COVER. AVIATION...00Z TAFS SCATTERED TO BROKEN CUMULUS SHOULD DISSIPATE ACROSS MUCH OF THE CWA THIS EVENING...WITH A MORE SOLID DECK OF CLOUDS MOVING SOUTH OUT OF ONTARIO THAT MAY IMPACT THE ARROWHEAD TONIGHT. THERE WILL ALSO BE SOME HIGH CLOUDS MOVING THROUGH OVERNIGHT. SOME PATCHY FOG WILL BE POSSIBLE OVERNIGHT...AND WE CONFINED THE MENTION TO KHYR/KHIB FOR NOW. MORE SCATTERED TO BROKEN VFR CUMULUS SHOULD FORM ON SATURDAY. PREV DISCUSSION... /ISSUED 330 PM CDT FRI AUG 2 2013/ CURRENT...LATEST RAP40 SHOWS JET MAX ASSOCIATED WITH HUDSON BAY TROF IS MOVING EAST OF REGION SIGNALING THE BEGINNING OF A TRANSITION TO DRY WEATHER. THE EXCEPTION IS OVER THE ARROWHEAD THIS AFTN WHERE PROXIMITY TO THE DEPARTING UPPER THERMAL TROUGH IS GENERATING INSTABILITY RW. ELSEWHERE SCT/BKN CU IS WIDESPREAD AS RESIDUAL MOISTURE IS LIFTED IN BDRY LYR. CANOPY OF HIGH LVL CIRRUS CLOUDS MOVING ACROSS SRN CWA IS CONVECTIVE DEBRIS FROM STORMS OVER NRN PLAINS. TONIGHT/TOMORROW...AS UPPER TROF MOVES EAST ACROSS ONTARIO A LARGE SFC HIGH WILL BEGIN ITS MOVE FROM MANITOBA INTO THE REGION. ANY SHOWER ACTIVITY OVER THE ARROWHEAD WILL DIMINISH THIS EVENING. MDLS SUGGEST A LOW PROB OF RW TOMORROW OVER ERN ARROWHEAD BUT HAVE KEPT INHERITED DRY FCST FOR NOW. MIXING LAYER DEEPENS TO AROUND 5K SATURDAY SO WE MAY STILL HAVE OCCASIONAL GUSTS IN THE AFTERNOON. TEMPS WILL REMAIN BELOW CLIMO THIS PERIOD. LONG TERM...SATURDAY NIGHT THROUGH THURSDAY... MID LEVEL RIDGING WITH SFC HIGH PRESSURE WILL BUILD INTO THE WESTERN GREAT LAKES REGION LATE SAT THROUGH SUN. THE SFC HIGH WILL BRING GENERALLY QUIET CONDITIONS WITH BELOW NORMAL TEMPERATURES AND LIGHT WINDS. CLEAR SKIES AND LIGHT WINDS SUNDAY NIGHT ARE EXPECTED TO ALLOW OVERNIGHT LOWS TO DIP INTO THE LOW 40S...TO EVEN A FEW UPPER 30S NEAR DAYBREAK SUNDAY. THE MEX GUIDANCE FOR KHIB OVER THE PAST SEVERAL RUNS HAS CONSISTENTLY SHOWN A LOW TEMP OF 38 F SUNDAY MORNING. FOCUS TURNS TO A LONG WAVE TROUGH THAT DROPS ACROSS THE DAKOTAS MONDAY...BRINGING INCREASING SHOWER AND TSTORM CHANCES TO MN AND NRN WI MON NIGHT THROUGH TUES NIGHT. HAVE SLOWED TIMING FOR THE POPS AS LATEST ECM/GFS RUNS CONTINUE TO BACK OFF ON THE PROGRESSION OF THE WAVE. THE TIMING MAY HAVE TO CONTINUE TO BE REFINED BUT FOR NOW HAVE KEPT BROADBRUSH CHC POPS MONDAY/MON NIGHT DUE TO INSTABILITY AHEAD OF THE FRONT. BEST CHANCE FOR STORMS IN THE NORTHLAND WILL ARRIVE WITH A FRONTAL PASSAGE TUESDAY AFTERNOON/EVENING. EXTENDED...LONG RANGE MODELS ARE SHOWING A COLD CORE LOW SETTLES OVER MANITOBA MID-WEEK...THEN GRADUALLY SHIFTS EAST ALONG THE CANADIAN BORDER INTO THE WEEKEND. ALTHOUGH HIGHLY DEPENDENT ON THE TRACK POSITION...THERE IS GOOD AGREEMENT H85 TEMPS FALL INTO THE LOWER SINGLE DIGITS WITH THIS LOW...LEADING TO WELL BELOW NORMAL TEMPS AND CLOUDS INTO THE WEEKEND. && .POINT TEMPS/POPS... DLH 48 74 50 71 / 0 10 10 20 INL 43 72 48 73 / 0 10 10 10 BRD 47 75 53 75 / 0 10 30 30 HYR 46 75 51 73 / 0 10 10 30 ASX 48 74 51 72 / 0 10 10 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...GROCHOCINSKI LONG TERM....STEWART AVIATION...STEWART
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
624 PM CDT Sun Aug 4 2013 .SHORT TERM...(This Evening through Monday Night) Issued at 406 PM CDT SUN AUG 4 2013 Tonight...12Z operational models, especially the NAM, had difficulty evaluating the mesoscale features from last nights/todays MCS with double MVC...mesoscale vorticity center...structure. As one would expect the short range HRRR did a much better job with this system. The trailing MVC now moving into southeastern KS is aiding downstream scattered areas of rain from the southern CWA southward across southern MO. The latest HRRR maintains this area of precipitation through mid evening and then steadily diminishes it. Will follow this trend for the evening hours. Thunder chances look minimal owing to less than stellar instability due to the rain-cooled airmass and extensive cloud shield. Looking upstream within the monsoonal flow circulating around the Southern Plains upper high yields little if any clues for the next shortwave or disturbance aloft which could generate new convection. However, believe convection for the overnight hours lies with the increasing southwesterly low level jet that is expected to form from the Southern Plains into KS. GFS and NAM output both signal increasing moisture convergence and isentropic ascent will likely generate another convective complex. Due to the subsidence left behind from todays MCS and the models poor handling of this feature have some question as to where this convection will form. For now will place my bet on southeastern KS with the activity spreading into and across mainly the southern CWA. In addition to the rain tonight am expecting to see MVFR type fog form. Monday-Monday night...Models show no discernible disturbances embedded with the northwest flow which will affect the CWA during the daylight hours. So, rain chances are most likely tied to the morning hours and across the far southern counties where the combo of isentropic lift and a weakening low level jet aid a departing MCS. Have backed off on high temperatures by a handful of degrees as warm front not likely to move into the CWA and amount of residual cloud cover will impact surface heating. The nocturnal low-level jet is expected to reform Monday night and enhance the lift along/north of the surface front which is expected to lift northward across central/eastern KS and west central MO later in the evening. Have moderate confidence this will generate some healthy convection and will increase PoPs after midnight for the western counties. .LONG TERM...(Tuesday through Sunday) Issued at 406 PM CDT SUN AUG 4 2013 Slight northwest to almost zonal type flow regime will continue across the central US as the Hudson Bay vortex across southern Canada will deepen as it slowly progresses towards southern Ontario and the northern Great Lakes region. A shortwave trough will rotate along the periphery of this system and help to push a cold front southeastward through the Central Plains. This front will near the area by Tuesday night and will be the focus for convective development Tuesday night into Wednesday morning. The expected MCS will initially develop north of the CWA, along the front, during the afternoon and gradually make its way into the CWA as the evening progresses. The remainder of the week will see spotty precipitation chances as the Hudson Bay low gradually moves eastward and ridging remains positioned across the Rockies. A few shortwave troughs may ride the ridge and help to initiate convection across the region. Temperatures will be slightly cooler behind this front as surface high slides into the region, but will gradually warm into the mid 80s as we near the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) Issued at 614 PM CDT SUN AUG 4 2013 A combination of MVFR and IFR conditions are expected across the terminals tonight through Monday morning. Late night redevelopment of storms across southeast Kansas and southern Missouri should remain south of Kansas City, so low clouds and possible mist or surface fog might be issues overnight. Have gone a little pessimistic and put the terminals in the IFR range for much of the overnight hours. Additionally, with the potential for storms to the south through Monday morning, thoughts are that low clouds -IFR- will likely hangout through noon Monday. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...MJ LONG TERM...PMM AVIATION...Cutter
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
854 PM MDT SUN AUG 4 2013 .UPDATE... VERY MOIST ATMOSPHERE REMAINS OVER THE AREA THIS EVENING...BUT LITTLE TO NO FORCING AVAILABLE TO GENERATE THUNDERSTORMS OUT OF IT. CAPE VALUES ARE IN THE 2-4000J/KG RANGE OVER EASTERN ZONES WITH STRONG SHEAR...BUT JUST NOT QUITE ENOUGH LIFT TO GET UPDRAFTS ESTABLISHED. AS A RESULT HAVE DROPPED PRECIPITATION CHANCES FOR ALL BUT THE BEARTOOTH FRONT THIS EVENING. ADDED MENTION OF FOG TO CENTRAL AND EASTERN ZONES ALONG WITH INCREASING CLOUD COVER OVERNIGHT AS ANOTHER ROUND OF FOG/STRATUS SEEMS ON TRACK GIVEN MOISTURE AND LACK OF ANY SUBSTANTIAL DRY AIR ADVECTION. TEMPERATURE FORECAST LOOKS ON TRACK. CHAMBERS && .SHORT TERM...VALID FOR MON AND TUE... WATER VAPOR IMAGERY SHOWS WEAK PV MAX MOVING THROUGH NE MT NOW. THIS ENERGY IS STRUGGLING TO PRODUCE MUCH IN THE WAY OF CONVECTION AS THE EASTERN MT AIRMASS IS A BIT DRIER AND CERTAINLY MORE CAPPED THAN YESTERDAY. A WEAK THUNDERSTORM DID DEVELOP OVER THE SNOWY MTNS BUT THIS CELL HAS NOT BEEN ABLE TO DETACH FROM THE HIGH TERRAIN SO FAR. ASCENT FROM AFOREMENTIONED SHORTWAVE IS GREATEST IN FAR EASTERN MT THIS AFTERNOON...WITH DESCENT EXPECTED BY EVENING...SO FORCING IS MINIMAL. NOT EXPECTING TOO MUCH ACTIVITY INTO THIS EVENING BUT FOCUS OF POTENTIAL STRONGER TSTMS MAY BE ALONG THE MT/WY BORDER FROM SHERIDAN COUNTY EASTWARD...IN AN AREA OF HIGHER THETA-E AIR AND A BIT MORE FAVORABLE LOW LEVEL WIND SHEAR NEAR STALLED SFC BOUNDARY. HRRR RUNS HAVE BEEN CONSISTENT IN KEEPING DEVELOPMENT MAINLY IN NE WY...WITH ONLY VERY WEAK CELLS FURTHER NORTH. WILL KEEP POPS IN LINE WITH THIS THINKING...AND WILL CONTINUE TO ADVERTISE THE POSSIBILITY OF A STRONGER STORM NEAR THE SE MT/WY BORDER INTO THE EARLY EVENING. EVENING ACTIVITY SHOULD BE DONE BY SUNSET AND THE REMAINDER OF THE NIGHT SHOULD BE DRY WITH A TREND TOWARD RIDGING ALOFT. HEIGHTS BEGIN TO FALL AGAIN BY TOMORROW AFTERNOON AS BRITISH COLUMBIA SHORTWAVE DROPS INTO WESTERN MT. SFC HEATING WILL DESTABILIZE THE AIRMASS ENOUGH TO ALLOW FOR SOME LATE AFTERNOON AND EVENING SHOWER/TSTM ACTIVITY...WITH ENHANCEMENT BY EVENING WITH A FRONTAL PASSAGE...THOUGH WITH A DRIER PREFRONTAL AIRMASS AS WE MIX W-NW MID LEVEL WINDS. FOCUS OF POTENTIAL STRONGER STORMS WILL AGAIN BE IN FAR SOUTHEAST MT WHERE MOISTURE/INSTABILITY WILL BE GREATEST ALONG WEAK SFC TROF/AREA OF PRESSURE FALLS. HAVE RAISED POPS TO SCATTERED ACROSS MUCH OF THE AREA BY MONDAY NIGHT PER FORCING FROM THE BC SHORTWAVE. EXPECT ISOLATED SHOWERS/TSTMS ON TUESDAY UNDER CYCLONIC NW FLOW ALOFT...BUT WITH NOTHING STRONG OR SEVERE AS DEEP MOISTURE/ INSTABILITY AXIS WILL BE SHIFTED WELL INTO THE CENTRAL PLAINS. TEMPERATURES ON MONDAY WILL JUMP UP WITH PREFRONTAL WARMING AND A PERIOD OF DOWNSLOPE WINDS. SHOULD SEE TEMPS NEAR 90 DEGREES FOR THE FIRST TIME IN AWHILE. TUESDAY WILL BE SEVERAL DEGREES COOLER THOUGH...AND BACK BELOW NORMAL...IN A POST FRONTAL REGIME WITH SOMEWHAT GUSTY NW WINDS. JKL .LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN... NO SIGNIFICANT CHANGES WERE MADE TO THE EXTENDED PERIOD FOR THIS FORECAST PACKAGE. MODELS CONTINUE TO BE CONSISTENT WITH A POWERFUL UPPER LOW OVER THE HUDSON BAY AREA DIRECTING OUR OVERALL WEATHER PATTERN. THIS KEEPS US IN QUASI CYCLONIC TO NORTHWEST FLOW ALOFT WITH OCCASIONAL BACK DOOR COLD FRONTS SLIPPING INTO EASTERN MONTANA. THE TIMING AND STRENGTH OF THESE FRONTS ARE IN QUESTION AS THE GFS AND ECMWF OFFER SOMEWHAT DIFFERENT SOLUTIONS. MAIN THEME THOUGH IS SAME...COOLER THAN NORMAL AND AT LEAST SOMEWHAT UNSETTLED. BT && .AVIATION... OUR CONFIDENCE IS INCREASING IN THE DEVELOPMENT OF STRATUS AND/OR LOCAL FOG TONIGHT INTO MONDAY MORNING FROM KBIL TO KMLS...KBHK... AND ACROSS THE REST OF SOUTHEASTERN MT. THE KSHR AREA MAY ALSO BE IMPACTED. EXPECT MVFR OR IFR CONDITIONS IN ANY OF THE STRATUS AND FOG THAT DOES FORM. OTHERWISE...THE NEXT POTENTIAL WEATHER IMPACT TO AVIATION WILL COME MONDAY AFTERNOON AND EVENING...WHEN A FRONT MAY KICK OFF SOME THUNDERSTORMS. SCHULTZ && .PRELIMINARY POINT TEMP/POPS... MON TUE WED THU FRI SAT SUN ----------------------------------------------------------- BIL 058/090 059/081 057/084 058/079 057/081 058/085 059/086 12/T 32/T 21/U 12/T 22/T 22/T 22/T LVM 052/088 050/084 051/084 052/083 051/082 051/086 052/086 12/T 32/T 21/B 12/T 22/T 23/T 22/T HDN 056/092 058/084 054/085 057/081 057/084 058/087 059/088 12/T 32/T 21/U 11/B 22/T 22/T 22/T MLS 057/091 060/080 056/083 057/079 055/082 058/086 061/087 12/T 32/T 11/U 21/B 22/T 22/T 22/T 4BQ 056/090 058/081 052/083 054/081 053/081 056/085 058/087 12/T 32/T 11/U 11/B 22/T 22/T 22/T BHK 053/087 058/076 049/077 052/075 051/077 053/079 056/080 12/T 32/T 11/U 21/U 12/T 21/B 22/T SHR 055/091 055/083 052/084 053/082 053/083 055/087 056/088 12/T 32/T 21/U 22/T 22/T 22/T 22/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GLASGOW MT
818 PM MDT SUN AUG 4 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY... EVENING UPDATE... NO CHANGES ANTICIPATED. GOING FORECAST LOOKS GOOD FOR TONIGHT. SHOWERS AND THUNDERSTORMS HAVE EXITED THE AREA. COLL HIGH PRESSURE WILL FILTER IN WITH PARTLY CLOUDY SKIES AND DRY CONDITIONS. RADAR TRENDS APPEAR TO SHOW A THIN LINE WHERE A CLUSTER OF OUTFLOW BOUNDARIES HAVE FIRMED UP INTO A FRONT AND ARE SLOWLY DRIFTING SOUTH. THERE APPEARS TO BE ABOUT A 7 TO 8 DEGREE DIFFERENCE ON EITHER SIDE OF THE FRONT. GAH PREVIOUS SHORT TERM DISCUSSION... AS THE REMNANTS OF THE SHEARED LOW PRESSURE SYSTEM FROM THE PACIFIC NORTHWEST FIZZLES OUT ALONG THE MONTANA-SASKATCHEWAN BORDER...VERY SMALL ISOLATED RAIN SHOWERS ARE GETTING A START ACROSS A FEW PORTIONS OF NORTHEAST MONTANA. THE HRRR MODEL CONTINUES TO IGNORE THE THIN BAND OF LIGHT RAIN SHOWERS FROM JORDAN TO CIRCLE TODAY...BUT IS PERSISTENT IN SUPPORTING A LARGER CLUSTER OF THUNDERSTORMS MOVING FROM NORTHERN PHILLIPS COUNTY SOUTHEASTWARD THROUGH THE FORT PECK AREA LATER THIS AFTERNOON AND EVENING. TRIED TO BETTER REPRESENT THESE TRENDS IN THE FORECAST GRIDS AND PLAN TO ISSUE THE FORECAST WITH A PRE- FIRST PERIOD TO REPRESENT THIS THINKING TO THE PUBLIC. TONIGHT...UPPER LEVEL FLOW OVER MONTANA SHOWS A VERY SMALL SCALE RIDGE INFLUENCE FROM THE SOUTH BETWEEN SYSTEM BEFORE THE FLOW OVER OUR REGION FALLS UNDER GREATER INFLUENCE FROM THE LARGE UPPER LOW COMPLEX TOWARDS THE NORTHEAST...COURTESY OF THE RELATIVELY ARCTIC INTRUSION FROM THE HUDSON BAY REGION. THE ATTENDANT COLD FRONT WILL MOVE THROUGH OUR CWA SOMETIME AFTERNOON TUESDAY AFTERNOON AND WILL RESULT IN ABOUT A 10 DEGREE DROP IN DAYTIME TEMPERATURES THROUGH MOST OF THE WORK WEEK. AFTER A DRY MONDAY MORNING TOMORROW...THIS OTHER STEERING INFLUENCE WILL INTRODUCE PERIODS OF SCATTERED SHOWERS AND THUNDERSTORMS THROUGH PORTIONS OF THE CWA THROUGH THE REMAINDER OF THE FORECAST PERIOD. FORCING FOR ASCENT WILL REMAIN NEUTRAL OR MINIMAL AT BEST AND NO SIGNIFICANT WEATHER SYSTEMS ARE EXPECTED TO IMPACT THE REGION. BMICKELSON .LONG TERM...TUESDAY NIGHT THROUGH SUNDAY... UPDATE...VERY LITTLE CHANGE IN THE EXTENDED FORECAST. GUIDANCE KEEPS WITH THE PREVIOUS FORECAST. DID ADD VERY LOW POPS TO THE END OF THE FORECAST WITH THE SPREAD OF THE GUIDANCE BEING ENOUGH TO BRING A SLIM CHANCE OF PRECIPITATION. THE ONLY MAJOR CHANGE OTHER THAN BRUSHING UP THE EDGES WITH CHANGES MADE AROUND THE REGION. PROTON PREVIOUS DISCUSSION... SYNOPTIC SET UP A CLOSED LOW EXISTS OVER THE THE ONTARIO/MANITOBA BORDER WITH A COLD FRONT EXTENSION OVER THE UPPER MISSISSIPPI VALLEY THE NORTHERN US PLAINS AND THE CENTRAL US HIGH PLAINS. COLD AIR BEHIND THE FRONT WILL SMASH THE INTENSITY OF THE LARGE HEAT DOME OVER THE FOUR CORNERS AND REDUCING IT TO A RIDGE OVER THE INTER-MOUNTAIN WEST AND BRITISH COLUMBIA. A LARGE TROUGH IS DEVELOPING OVER THE GULF OF ALASKA WITH A FAR WEAKER TROUGH OFF THE COAST OF CALIFORNIA AND THE PACIFIC NORTHWEST. TUESDAY NIGHT THROUGH FRIDAY... NORTHEAST MONTANA LIES IN A ZONAL TO NORTHWEST FLOW PATTERN WITH WEAK SHORTWAVES COMING ACROSS ON A REGULAR BASIS. TIMING OF THE WAVES IS DIFFICULT. HOWEVER... THE TROUGH OVER ONTARIO AND MANITOBA WILL SEND A COLD FRONT DOWN THROUGH THE AREA WEDNESDAY EVENING. TEMPERATURES ARE ANTICIPATED TO COOL OFF BY ABOUT 10 DEGREES POST FRONT FOR HIGHS AND LOWS WITH THE AFFECT LINGERING THROUGH FRIDAY EVENING. CHANCES FOR RAIN WILL EXIST ALONG AND BEHIND THE FRONT. SATURDAY ONWARD... THE LARGE TROUGH OVER ONTARIO WILL PUSH EAST INTO QUEBEC ALLOWING THE LARGE RIDGE TO THE WEST TO GAIN INCREASING DOMINION OVER THE NORTHEAST MONTANA WEATHER PATTERN. EXPECTED TEMPERATURES TO CREEP UPWARDS TO NEAR NORMAL AGAIN WITH CHANCES FOR RAIN DROPPING SLOWLY. GAH && .AVIATION... VFR. MAINLY CLEAR SKIES TONIGHT WITH POSSIBLE LOW CLOUDS REDEVELOPING LATE TONIGHT...ESPECIALLY NORTHEAST OF A WOLF POINT TO SIDNEY LINE. SCATTERED SHOWERS AND THUNDERSTORMS LOOK TO RE- ENTER THE PICTURE LATE MONDAY AS ANOTHER DISTURBANCE ARRIVES FROM THE NORTHWEST. JAMBA && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
717 PM CDT SUN AUG 4 2013 .SYNOPSIS... LITTLE CHANGE TO THE OVERALL PATTERN IN THE LAST 24 HOURS. UPPER LEVEL RIDGE REMAINS CENTERED OVER NW TX. SEVERAL SHORT WAVES RIDING AROUND THE PERIPHERY OF THE RIDGE...WITH GOOD TAP TO TROPICAL MOISTURE. AT THE SFC SOUTHEASTER FLOW CONTINUES TO PUMP MOISTURE INTO THE REGION. DEW PTS HAVE CREPT UP INTO THE MID 60S...WITH LOWER 70S ACROSS MUCH OF KANSAS. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 345 PM CDT SUN AUG 4 2013 TONIGHT...THE NEXT SHORT WAVE RIDING ACROSS THE CENTRAL ROCKIES WILL BE THE FOCUS FOR CONVECTION ALONG THE FRONT RANGE. SOME UNCERTAINTY TO THE SUSTAINABILITY FOR THE STORMS AS THEY MOVE OFF THE HIGHER TERRAIN. THE HRRR SUGGESTS THE STORMS WILL MAKE IT INTO WESTERN NEBRASKA...WHILE THE NAM/RUC FAVOR NORTHERN NEB...UTILIZED THE BLACK HILLS FOR INITIATION. THE NOSE OF THE LL JET OVERNIGHT FOCUSES NEAR THE NEB/S DAKOTA BORDER AND WILL FAVOR THE NORTHERN ZONES WITH THE HIGHEST POPS. LOW LEVEL MOISTURE REMAINS EXCELLENT AND GUIDANCE IN AGREEMENT WITH LOW CLOUDS TO CONTINUE/REDEVELOP ACROSS THE AREA OVERNIGHT. COULD SEE SOME FOG ACROSS SW NEB AS DEW POINTS ARE UP A FEW DEGREES FROM THE PAST COUPLE OF DAYS AND EXPECT TO EASILY SEE 100 PERCENT RH AS TEMPS COOL INTO THE LOWER TO MID 60S...HOWEVER THE LATEST MOS GUIDANCE HOLD VSBY IN THE 4 TO 6 MILE RANGE AND FORECAST FAVORS THE LOW STRATUS WITH POCKETS OF FOG. NOT EXPECTING FOG TO BE WIDESPREAD ENOUGH AT THIS TIME TO INCLUDE IN FORECAST...HOWEVER WILL MONITOR. MONDAY...LINGERING THUNDERSHOWERS ACROSS NORTH CENTRAL NEBRASKA SHOULD DECAY IN THE MORNING WHILE STRATUS ELSEWHERE WILL BE SLOW TO ERODE. ANOTHER SHORT WAVE...A STRONGER SYSTEM...WILL ENTER THE REGION FOR THE AFTERNOON. AS THE CLOUDS FINALLY BEGIN TO BREAK AND TEMPS QUICKLY BUMP INTO THE 80S WITH A FEW LOWER 90S ACROSS THE SW...GROWING INSTABILITY SHOULD BE ENOUGH FOR CONVECTION. SPC HAS A SLIGHT RISK IN PLACE FOR WESTERN NEBRASKA AND AGREE WITH 40 TO 50 KTS OF SHEAR WITH DEW PTS IN THE 60S. THUNDERSTORMS SHOULD BREAK THE CAP IN THE AFTERNOON. PRECIPITABLE WATER AROUND 130 TO 150 PERCENT OF NORMAL SHOULD BE SUFFICIENT FOR LOCALLY HEAVY RAINFALL. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 345 PM CDT SUN AUG 4 2013 MONDAY NIGHT THROUGH WEDNESDAY...DESPITE THE DEEP MOISTURE...THE MODELS ARE BACKING OFF ON ANY SORT OF WIDESPREAD HP EVENT LATE MONDAY. IT MAY BE THAT THE CAP IS VERY STRONG IN THE LATEST SOLNS SHOWING A STRENGTHENING CAP OF 12C TO 14C AT 700 MB ACROSS WRN NEB AND THE UPPER LEVEL FORCING IS WEAK MONDAY. MODEL BLENDED POPS ARE AROUND 30 PERCENT AND QPF IS LESS THAN 1/10 OF AN INCH FOR MONDAY NIGHT. ON TUESDAY A COLD FRONT WILL DROP THROUGH THE FCST AREA PROVIDING FOCUS FOR STORM DEVELOPMENT. THE 00Z WEDNESDAY MODEL CONSENSUS SHOWS THE SFC LOW ACROSS SWRN KS WHICH IS A POST FRONTAL ENVIRONMENT FOR POPS ACROSS THE FCST AREA. THE GEM...GFS AND ECM ARE KEYING ON MOISTURE TRAPPED BEHIND THE COLD FRONT ACROSS ERN PTNS OF NCNTL NEB WHERE THE CAP WILL BE WEAKEST. POPS ARE 40 PERCENT THERE IN THE AFTN BUT FALL OFF TUESDAY EVENING AS A MCS DROPS SOUTH THRU CNTL AND ERN NEB. ALL MODELS SHOW A 12C-14C CAP ACROSS SWRN NEB TUESDAY WHICH IS LIKELY LIMITING CONVECTION. THIS THERMAL RIDGE WILL DROP SOUTH LATE TUESDAY AFTN WHICH COULD OPEN UP THE FCST AREA TO MORE WIDESPREAD CONVECTION THAN INDICATED BY THE MODELS. THE FRONT WILL DROP SOUTH ON THE HEALS OF A 300 MB JET IN COMBINATION WITH A DEEP UPPER LEVEL LOW DROPPING THROUGH MANITOBA. THIS PRODUCES 45 TO 55 KT OF 0-6KM BULK SHEAR TUESDAY AFTN WITH ML CAPE OVER 3000J/KG EAST OF HIGHWAY 83. THE SHEAR AND CAPE VALUES ARE MUCH WEAKER MONDAY EVENING SO THE BEST CHANCE FOR SEVERE WEATHER IS TUESDAY ALONG AND EAST OF HIGHWAY 83. THE DEEP UPPER LEVEL CYCLONE DROPPING THRU MANITOBA WILL PUSH A STRONG COLD FRONT THROUGH THE FCST AREA WEDNESDAY AND HIGH TEMPS WILL STRUGGLE TO REACH 80F. HIGHS TUESDAY RISE INTO THE LOWER 90S SOUTH WITH THE THERMAL RIDGE OVERHEAD. 80S ARE EXPECTED ELSEWHERE. ANY CONVECTION THAT FIRES SHOULD BE MOSTLY SOUTH AND WEST OF THE FCST AREA. THERE IS A GLITCH IN THE FORECAST THOUGH. THE 18Z NAM IS LIFTING A SUBTROPICAL SHORT WAVE THROUGH SWRN NEB WEDNESDAY AFTN. THE GEM...ECM AND GFS MOVE THIS WAVE THROUGH KS SOUTH OF THE FCST AREA. FOR THE FCST USES THE CONSENSUS WHICH IS FOR ISOLATED STORMS ACROSS THE SOUTH WEDNESDAY. WEDNESDAY NIGHT THROUGH SUNDAY...A NEW DEVELOPMENT IN THE 12Z MODEL RUNS IS THEY ARE NOT NEARLY AS STRONG WITH A REINFORCING COLD FRONT THAT WAS FCST TO PULL VERY COOL AIR SOUTH OUT OF CANADA. THE GFS ENSEMBLE HOLDS THE HIGH ACROSS MANITOBA AND SASKATCHEWAN WITH A STATIONARY FRONT DRAPED ACROSS THE CNTL PLAINS. IN FACT THE FCST AREA REMAINS UNDER SOUTH AND SOUTHEAST WINDS AT 850 MB. NOW THE ALLBLEND TOTAL QPF FOR THIS PERIOD SHOWS AROUND 1 INCH ACROSS SCNTL NEB TO LESS THAN 1/4 OF AN INCH ACROSS WRN/NRN NEB SUGGESTING A STATIONARY FRONT WILL OPERATE ACROSS THE FCST AREA. POPS ARE STILL ISOLATED TO SCATTERED AND TEMPS ARE A BIT WARMER...UPPER 70S TO LOWER 80S. IT WOULD APPEAR THAT THE SOUTHERLY WINDS ARE BACKED AROUND THE MANITOBA HIGH. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 715 PM CDT SUN AUG 4 2013 MVFR CEILINGS WILL LIFT AT KVTN THIS EVENING BEFORE BUILDING BACK INTO MOST OF WESTERN NEBRASKA THROUGH THE EARLY MORNING. SOME ISOLATED THUNDERSTORMS MAY MAKE IT OFF THE HIGHER TERRAIN TO THE WEST AND MOVE ACROSS WESTERN NEBRASKA THROUGH THE EARLY MORNING HOURS BUT DON`T HAVE A LOT OF CONFIDENCE WITH THIS AND HAVE LEFT OUT OF TAFS FOR NOW. SKIES WILL CLEAR OUT EARLY OVER WESTERN NEBRASKA MONDAY. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MASEK LONG TERM...CDC AVIATION...POWER
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
542 PM MDT SUN AUG 4 2013 .AVIATION... 00Z TAF CYCLE NEW TS DEVELOPMENT WILL BE FOCUSED ALONG OUTFLOW BOUNDARY COLLISIONS THRU THE EVENING...ESPECIALLY IN THE RIO GRANDE VALLEY...AND EC PLAINS. LATEST HI-RES MODELS SUGGEST SHRA CONTINUING INTO THE OVERNIGHT PERIOD AT KSAF AND KABQ AS WELL AS THE NORTHERN MTS. MT TOPS MAY BE OCCASIONALLY OBSCURED. OTHERWISE...TS WILL CONTINUE ACROSS WEST CENTRAL AND NORTHEAST NM WITH SMALL HAIL...HVY RAIN...LOW VSBY...FREQ LTG AND GUSTY WINDS THRU AT LEAST 06Z. VSBY MAY DROP BELOW 2 MILES IN HVY RAIN. MONDAY WILL BE NEARLY A REPEAT OF TODAY WITH STORMS INITIALLY FIRING OVER THE HIGH TERRAIN AND NE NM BY LATE MORNING/EARLY AFTN...THEN SPREADING ONTO THE LOWER ELEVATIONS BY MID/LATE AFTN/EVE. 34 && .PREV DISCUSSION...216 PM MDT SUN AUG 4 2013... ...INCREASED POTENTIAL FOR LOCALLY HEAVY RAINFALL THROUGH TONIGHT... RADAR TRENDS INDICATING SCATTERED TO NUMEROUS STORMS ACROSS THE HIGH TERRAIN OF CENTRAL NM. 19Z LAPS ANALYSIS SHOWS A SIGNIFICANT AMOUNT OF MOIST INSTABILITY OVER THE AREA WITH 2000-3500J/KG CAPE AND LIFTED INDICES BTWN -3 AND -6C FROM THE RGV INTO THE NE PLAINS. 700-500MB STORM MOTION VECTORS ARE NORTH NEAR 5 KTS WHICH IS MUCH SLOWER THAN YESTERDAY...SO THE HEAVY RAINFALL THREAT IS HIGHER AS WELL. PLACED MENTION OF LCL HEAVY RAIN IN GRIDS BUT WILL NOT ISSUE A FLASH FLOOD WATCH. OUTFLOW BOUNDARIES WILL ACTIVATE IN THIS REGIME TO PRODUCE MORE STORMS FOR VALLEY AREAS LATER IN THE DAY AS SHOWN BY THE RUC AND HRRR GUIDANCE. A LARGE PRECIP SHIELD IS LIKELY TO MOVE SLOWLY NORTH OVER CENTRAL NM AS WELL TONIGHT. RAISED POPS CONSIDERABLY FOR THIS REGION. MONDAY WILL BE AN ACTIVE DAY AGAIN. THE GFS INDICATES PWAT VALUES WILL TREND DOWN JUST SLIGHTLY AND THE MAIN AXIS OF INSTABILITY WILL SHIFT A LITTLE EAST ONTO THE HIGH PLAINS. STORM MOTIONS WILL BE MORE SOUTHWESTERLY AND SLOW AGAIN. THIS WILL BRING A LITTLE MORE COVERAGE TO THE EASTERN PLAINS DURING THE EVENING. WESTERN NM WILL STILL SEE VERY WEAK STORM MOTIONS WITH LCL HEAVY RAINFALL. TUESDAY IS EXPECTED TO BE ACTIVE AS WELL. AN EASTERLY WAVE NOTED ON WATER VAPOR ALONG THE WEST CENTRAL MEXICAN COAST WILL SHIFT NORTH AND IMPACT EASTERN AZ/WESTERN NM. RAISED POPS FOR TUESDAY. STEERING FLOW WILL INCREASE MORE BUT STILL REMAIN LIGHT ENOUGH FOR HEAVY RAINERS. DRIER MORE STABLE AIR WILL WORK INTO WESTERN/CENTRAL NM BEHIND THE UPPER WAVE. STORM COVERAGE WILL DIMINISH CONSIDERABLY FOR THE WEST. THIS UPPER WAVE WILL BECOME CAUGHT UP IN NORTHWEST FLOW OVER THE CENTRAL PLAINS STATES AND ENHANCE A SURFACE BACK DOOR FRONTAL BOUNDARY OVER NORTHEAST NM. THE NAM IS BULLISH WITH THE STRENGTH OF THIS SURFACE BOUNDARY AND THE COVERAGE OF STORMS. OVERALL THE PATTERN THROUGH THE REMAINDER OF THE WEEK LOOKS TO LOCK IN A VERY WELL DEFINED MONSOONAL CIRCULATION OVER CENTRAL/WESTERN NM. GUYER .FIRE WEATHER... UPPER HIGH ANCHORED OVER CENTRAL TEXAS WILL SLOWLY SHIFT TOWARD THE EAST AND SOUTH THROUGH LATE TUESDAY...BECOMING ELONGATED NEAR THE TX GULF COAST REGION BY WEDNESDAY MORNING. WELL ADVERTISED UPTICK IN THUNDERSTORM COVERAGE FOR THIS AFTERNOON HAS PANNED OUT WELL WITH STORM MOTIONS GENERALLY TOWARD THE NORTH-NORTHEAST AT 15 MPH OR LESS. OUTFLOW BOUNDARY INTERACTIONS IN THE PRESENCE OF A MUCH MORE UNSTABLE ENVIRONMENT SHOULD RESULT IN QUITE A BIT MORE THUNDERSTORM ACTIVITY IN THE VALLEYS BY MID TO LATE AFTERNOON AND INTO THE EVENING AS COMPARED TO SATURDAY...WITH THE POTENTIAL FOR HEAVY THUNDERSTORM RAINS INCREASING AND EXPANDING ACROSS THE NORTHEAST. THE UPPER FLOW REGIME WILL FAVOR LATE NIGHT OR NOCTURNAL SHOWERS FOR AREAS BETWEEN THE CONTINENTAL DIVIDE AND CENTRAL MOUNTAIN CHAIN WITH THE CENTRAL VALLEY CORRIDOR ESPECIALLY FAVORED. WELL-ESTABLISHED MONSOON PLUME ALONG THE WESTERN PERIPHERY OF THE RIDGE WILL CHANGE VERY LITTLE OVER THE NEXT 24-36 HOURS. LINGERING CLOUD COVER MONDAY MORNING MAY LIMIT EARLY DAYTIME HEATING AND THUS TOMORROW/S CROP OF THUNDERSTORMS MAY NOT BE QUITE AS WIDESPREAD AS TODAY BUT THE PATTERN WILL REMAIN FAVORABLE FOR THE WESTERN TWO-THIRDS OF THE AREA. TUESDAY WILL MARK A TRANSITION TO A RELATIVELY FASTER SW TO NE STEERING FLOW...AND POSSIBLY AN ENHANCED WINDOW OF MOISTURE/DYNAMIC FORCING ASSOCIATED WITH AN EASTERLY WAVE THAT WILL SLOWLY APPROACH THE REGION IN THE CLOCKWISE FLOW AROUND THE HIGH. WHILE MODELS SHOW THIS FEATURE TRACKING NORTH-NORTHWEST WELL TO OUR SOUTHWEST...ITS REMNANTS SHOULD EVENTUALLY WORK BACK TOWARD THE EAST AND THE FOUR CORNERS. MEDIUM RANGE GUIDANCE SHOWING SOME NICE CONSISTENCY THUS FAR AND WE WILL SEE IF THE TREND CONTINUES. OVERALL LOW CONFIDENCE IN WHAT WILL BECOME OF THIS FEATURE...HOW FAR NORTH IT MAY TRACK BUT THE MODELS ARE GENERALLY IN DECENT AGREEMENT SHOWING THE WAVE TRANSLATING EASTWARD OVER SOUTHERN COLORADO AND NORTHERN NEW MEXICO WED-WED PM. AT THE SAME TIME...A GOOD LOOKING BACKDOOR COLD FRONT IS INDICATED TO SURGE SOUTHWARD SETTING UP A POTENTIALLY VERY ACTIVE PATTERN FOR AREAS EAST OF THE CENTRAL MOUNTAIN CHAIN AND ESPECIALLY THE NORTHEAST. EXTENT OF LOWER LEVEL DRYING ACROSS THE WEST REMAINS A BIG QUESTION MARK...AS MODELS ARE QUITE AGGRESSIVE IN DRYING DEW POINTS DURING THE WED/THU PERIOD. KJ && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
302 PM EDT SAT AUG 3 2013 .SYNOPSIS... ISOLATED SHOWERS WILL DIMINISH TONIGHT WITH FAIR BUT CHILLY WEATHER EXPECTED. A COOL HIGH PRESSURE SYSTEM WILL BUILD INTO GREAT LAKES AND OHIO VALLEY REGION SUNDAY WITH A FEW LAKE EFFECT RAIN SHOWERS AFFECTING MAINLY CENTRAL NEW YORK. THIS HIGH PRESSURE SYSTEM WILL BUILD FARTHER EAST AND COVER THE REGION FROM SUNDAY NIGHT THROUGH MONDAY NIGHT WITH FAIR WEATHER DURING THE DAY AND FAIRLY CHILLY TEMPERATURES BOTH SUNDAY NIGHT AND MONDAY NIGHT. VALLEY FOG WILL BE PREVALENT BOTH NIGHTS. THE NEXT CHANCE FOR A LITTLE RAIN WILL COME ON TUESDAY BUT IT WILL BE WIDELY SCATTERED. MOST OF TUESDAY SHOULD BE FAIRLY DRY AND MILDER AS THE HIGH PRESSURE SYSTEM MOVES OFFSHORE AND A SOUTHERLY RETURN FLOW DEVELOPS. && .NEAR TERM /THROUGH SUNDAY/... RADAR WAS LARGELY FREE OF ECHOES EARLY THIS AFTERNOON EXCEPT FOR A FEW VERY ISLD SHRA OCCASIONALLY POPPING UP HERE AND THERE BUT BEING SHORT-LIVED. ACVTY SEEMS TO BE A TAD MORE PREVALENT IN NE PA NR SFC FRNT WHICH EXTENDED FROM NRN CATSKILLS TO BTWN IPT AND AVP IN NE PA IN OUR FORECAST AREA. WATER VAPOR IMAGERY SHOWS SIGNIFICANT UPPER LEVEL WAVE MOVG ACRS NRN NEW ENGLAND AND SERN CANADA. THIS WAVE WAS ENHANCING STRG UPR CONFLUENCE ACRS NEW ENGLAND TO NOVA SCOTIA AND HENCE AN UPPER LEVEL JET STREAK WAS POSITIONED IN THIS AREA. ENHANCED DVRG IN THE RR QUAD OF THE JET WAS PROMOTING SOME LIFTING INTO NE PA AND ITS LOWER LEVEL AGEO FORCING WAS ALSO PUSH THE FRNT SOUTHWARD. BEST SHOT OF A FEW SHRA AND EVEN A LITTLE TSRA WILL BE MAINLY ACRS OUR FAR SE FORECAST AREA IN THE POCONOS TO SRN CATSKILLS FOR THE REST OF THE AFTERNOON DUE TO THIS DYNAMICAL FORCING. NORTH OF THE FRNT...THE CUMULUS WAS BUILDING BUT NOT TO EXTENT THAT I EARLIER THHOUGHT. THE ONLY EXCEPTION WAS OVER AREAS DIRECTLY DOWNWIND OF LAKE ONTARIO WHERE LAKE MOISTURE WAS ENHANCING LL MOISTURE AND LEADING TO DEEPER CUMULUS AND A LITTLE ISLD SHRA ACVTY AT TIMES. HENCE HAVE SOME ISLD CHC OF SHRA WELL N OF THE FRNT ACRS CNTRL NY AND NRN PA. THIS ACVTY WILL WANE SOON EXCEPT IN NC NY DOWNWIND OF LAKE ONTARIO. FOR TONIGHT...INITIALLY CUMULUS AND ISLD SHRA WILL FALL APART WITH LOSS OF INSOLATION. CONTINUED LL NW FLOW AND CAA WILL CONT ACRS THE RELATIVELY WARM WATERS OF LAKE ONTARIO. LAKE ONTARIO TEMPS WERE RUNNING ARND 20-21C AS 850 MB TEMPS DROP TO ARND 7-8C OR SO BY LATE TONIGHT. ADDTNLY ANOTHER SHRT WAVE WILL DROP SOUTHWARD OVERNIGHT REACHING SOUTHEAST ONTARIO AND WESTERN QUEBEC BY 12Z. LIFTING FROM THIS WAVE IN ASSCTN WITH LAKE MOISTURE WILL TRIGGER SHRA AGAIN LATER TONIGHT IN NC NY...WITH NO PRECIPITATION EXPECTED IN SC NY DOWN TO NE PA BEFORE 12Z. THEN FOR SUNDAY...UPPER LEVEL WAVE PASSES TO THE EAST BUT IS FOLLOWING BY AN EVEN CHILLIER SHOT OF AIR WITH 850 MB TEMPS DROPPING TO ARND 6C WHICH IS ABT A 14-15C DIFFERENTIAL. THE FLOW REMAINS ABT 310 OR SO WHICH WILL BRING LAKE MOISTURE DOWN INTO THE HILLS OF NC NY AND DOWN TO SC NY AND FAR NE PA. WITH INSOLATION AND COLD TEMPERATURES AT 850 MB I SEE ISLD TO SCT SHRA FROM NRN PA TO SC NY AND SCT SHRA INTO NC NY DIRECTLY DOWNWIND OF LAKE ONTARIO. THE ACVTY WILL WANE LATER IN THE DAY AS INSOLATION BREAKS UP ANY ORGANIZED LAKE EFFECT RAINS. HAVE SLGHT CHC IN NE PA TO LO CHC IN SC NY TO HIGH CHC IN NC NY FOR SUNDAY. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... HIGH PRESSURE WILL BUILD OVER THE REGION SUNDAY NIGHT AND CROSS THE REGION MONDAY AND MONDAY NIGHT WITH FAIR WEATHER. WITH LIGHT WINDS I EXPECT PLENTY OF VALLEY FOG LATE SUNDAY NIGHT AND LATE MONDAY NIGHT. FOR TUESDAY A WARM FRONT AND SOUTHERLY RETURN FLOW WILL LIKELY SPREAD A FEW SHRA INTO NE PA AND C NY. THE CMC...EURO...GFS AND NAM ALL INDICATE TO VARYING DEGREES THAT THERE WILL BE ENUF MOISTURE ADVECTION FOR SOME PATCHY SHRA ACTVY. I WENT SLGHT CHC FOR NOW FOR SHRA. OTHERWISE...FAIRLY QUIET ON TUESDAY AND A LITTLE MILDER. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... RISING HGTS ON TUE WILL RESULT IN SOME INCRSG CLDS BUT SHWRS SHD BE LIMITED DUE TO STUBBORN LL DRY AIR. YET ANOTHER DIGGING LOW APCHS FOR WED AND THU AND PUSHES A SFC BNDRY THRU THE AREA. GOOD GULF CONNECTIONS SHD LEAD TO GOOD CVRG OF SHWRS AND TRWS LATE WED INTO THU AHD OF THE TROF. DRIER AND COOLER AIR RETURNS ON FRI BHD THE FNT. ATTM IT LOOKS DRY BHD THE FNT BUT EVENTUALLY THE LWRG HGTS WITH THE LRG UA LOW WILL RESULT IN MAINLY AFTN CONV. TEMPS WILL CONT TO AVG WELL BLO SEASONAL NORMS THRU THE PD. MEX GUID WAS RUNNING A BIT HIER THRU THE PD THAN HPC BUT SEEMED LIKE THE COOLER EURO HAD A BETTER HANDLE ON THE UA LOW SO MORE CLOSELY FLWD HPC GUID. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... MUCH DRIER AIR CONTS TO STREAM INTO THE AREA BRINGING VFR CIGS AND VSBYS. SHRT WV DROPPING INTO THE UPR TROF WILL RETURN MVFR CIGS LATE TNGT AS THE WV GRABS MOISTURE OFF THE LAKES. OCNL SHRA OVER THE RME AND SYR PSBL AFT 08Z SHD NOT LIMT THE VSBYS. MVFR/VFR CIGS WILL CONT THRU THE END OF THE TAF PD WITH A CAA NW FLOW REGIME. WINDS WILL BE COME LGT TNGT...THEN NW ONCE AGAIN ON SUN WITH MIXING. MON THRU WED...MAINLY VFR. THU...MVFR IN SHRA AND TSRA. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM...DJN LONG TERM...DGM AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
203 PM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL GRADUALLY CROSS THE REGION THIS AFTERNOON. ALTHOUGH A FEW SHOWERS WILL PRECEDE THIS SYSTEM...MUCH OF THE DAY IS EXPECTED TO BE RAIN FREE. A COOLER NORTHWEST AIR FLOW WILL FOLLOW FOR THE SECOND HALF OF THE WEEKEND...ALONG WITH A FEW HIT AND MISS SHOWERS ON SUNDAY...MAINLY OVER CENTRAL NEW YORK. && .NEAR TERM /THROUGH SUNDAY/... RADAR WAS LARGELY FREE OF ECHOES EARLY THIS AFTERNOON EXCEPT FOR A FEW VERY ISLD SHRA OCCASIONALLY POPPING UP HERE AND THERE BUT BEING SHORT-LIVED. ACVTY SEEMS TO BE A TAD MORE PREVALENT IN NE PA NR SFC FRNT WHICH EXTENDED FROM NRN CATSKILLS TO BTWN IPT AND AVP IN NE PA IN OUR FORECAST AREA. WATER VAPOR IMAGERY SHOWS SIGNIFICANT UPPER LEVEL WAVE MOVG ACRS NRN NEW ENGLAND AND SERN CANADA. THIS WAVE WAS ENHANCING STRG UPR CONFLUENCE ACRS NEW ENGLAND TO NOVA SCOTIA AND HENCE AN UPPER LEVEL JET STREAK WAS POSITIONED IN THIS AREA. ENHANCED DVRG IN THE RR QUAD OF THE JET WAS PROMOTING SOME LIFTING INTO NE PA AND ITS LOWER LEVEL AGEO FORCING WAS ALSO PUSH THE FRNT SOUTHWARD. BEST SHOT OF A FEW SHRA AND EVEN A LITTLE TSRA WILL BE MAINLY ACRS OUR FAR SE FORECAST AREA IN THE POCONOS TO SRN CATSKILLS FOR THE REST OF THE AFTERNOON DUE TO THIS DYNAMICAL FORCING. NORTH OF THE FRNT...THE CUMULUS WAS BUILDING BUT NOT TO EXTENT THAT I EARLIER THHOUGHT. THE ONLY EXCEPTION WAS OVER AREAS DIRECTLY DOWNWIND OF LAKE ONTARIO WHERE LAKE MOISTURE WAS ENHANCING LL MOISTURE AND LEADING TO DEEPER CUMULUS AND A LITTLE ISLD SHRA ACVTY AT TIMES. HENCE HAVE SOME ISLD CHC OF SHRA WELL N OF THE FRNT ACRS CNTRL NY AND NRN PA. THIS ACVTY WILL WANE SOON EXCEPT IN NC NY DOWNWIND OF LAKE ONTARIO. FOR TONIGHT...INITIALLY CUMULUS AND ISLD SHRA WILL FALL APART WITH LOSS OF INSOLATION. CONTINUED LL NW FLOW AND CAA WILL CONT ACRS THE RELATIVELY WARM WATERS OF LAKE ONTARIO. LAKE ONTARIO TEMPS WERE RUNNING ARND 20-21C AS 850 MB TEMPS DROP TO ARND 7-8C OR SO BY LATE TONIGHT. ADDTNLY ANOTHER SHRT WAVE WILL DROP SOUTHWARD OVERNIGHT REACHING SOUTHEAST ONTARIO AND WESTERN QUEBEC BY 12Z. LIFTING FROM THIS WAVE IN ASSCTN WITH LAKE MOISTURE WILL TRIGGER SHRA AGAIN LATER TONIGHT IN NC NY...WITH NO PRECIPITATION EXPECTED IN SC NY DOWN TO NE PA BEFORE 12Z. THEN FOR SUNDAY...UPPER LEVEL WAVE PASSES TO THE EAST BUT IS FOLLOWING BY AN EVEN CHILLIER SHOT OF AIR WITH 850 MB TEMPS DROPPING TO ARND 6C WHICH IS ABT A 14-15C DIFFERENTIAL. THE FLOW REMAINS ABT 310 OR SO WHICH WILL BRING LAKE MOISTURE DOWN INTO THE HILLS OF NC NY AND DOWN TO SC NY AND FAR NE PA. WITH INSOLATION AND COLD TEMPERATURES AT 850 MB I SEE ISLD TO SCT SHRA FROM NRN PA TO SC NY AND SCT SHRA INTO NC NY DIRECTLY DOWNWIND OF LAKE ONTARIO. THE ACVTY WILL WANE LATER IN THE DAY AS INSOLATION BREAKS UP ANY ORGANIZED LAKE EFFECT RAINS. HAVE SLGHT CHC IN NE PA TO LO CHC IN SC NY TO HIGH CHC IN NC NY FOR SUNDAY. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... 5 AM UPDATE... DEEPENING NW FLOW TNT-SUN...AS THE MAIN UPR LVL TROUGH AXIS SHIFTS INTO QUE...WILL ALLOW A COOLER AMS TO SPREAD INTO NY/PA. LINGERING LOW LVL MOISTURE WILL COMBINE WITH THE PASSAGE OF ANOTHER S/WV LATE TNT INTO SUN...TO BRING SCTD -SHRA ACRS OUR CNY ZNS...ALSO HELPED BY SOME UPSLOPING VIA NWLY FLOW. 925-850 MB CAA ON SUN...ALG WITH AT LEAST MRNG CLDNS/SCTD -SHRA...WILL BRING COOLER READINGS (AS MENTIONED ABV)...WITH HIGH TEMPS PERHAPS STAYING IN THE UPR 60S FOR SXNS OF THE FA (SPCLY THE HIGHER TERRAIN ACRS CNY). SUN NGT-MON NGT... A LARGE SFC HIGH WILL BUILD INTO NY/PA FROM THE UPR MIDWEST. THIS WILL LEAD TO A CLEARING AND COOL NGT SUN NGT...FOLLOWED BY PTLY-MSTLY SUNNY SKIES MON...WITH HIGHS MAINLY IN THE 70S...AS THE COOLEST PTN OF THE AMS (850 MB TEMPS OF 4-6 C AT 12Z MON) BEGINS TO SHIFT TO OUR NE INTO NRN NEW ENG. WAA MON NGT COULD WELL LEAD TO SOME INCREASE IN MID TO UPR-LVL CLDNS...BUT CONDS STILL LOOK RAIN-FREE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... RISING HGTS ON TUE WILL RESULT IN SOME INCRSG CLDS BUT SHWRS SHD BE LIMITED DUE TO STUBBORN LL DRY AIR. YET ANOTHER DIGGING LOW APCHS FOR WED AND THU AND PUSHES A SFC BNDRY THRU THE AREA. GOOD GULF CONNECTIONS SHD LEAD TO GOOD CVRG OF SHWRS AND TRWS LATE WED INTO THU AHD OF THE TROF. DRIER AND COOLER AIR RETURNS ON FRI BHD THE FNT. ATTM IT LOOKS DRY BHD THE FNT BUT EVENTUALLY THE LWRG HGTS WITH THE LRG UA LOW WILL RESULT IN MAINLY AFTN CONV. TEMPS WILL CONT TO AVG WELL BLO SEASONAL NORMS THRU THE PD. MEX GUID WAS RUNNING A BIT HIER THRU THE PD THAN HPC BUT SEEMED LIKE THE COOLER EURO HAD A BETTER HANDLE ON THE UA LOW SO MORE CLOSELY FLWD HPC GUID. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... MUCH DRIER AIR CONTS TO STREAM INTO THE AREA BRINGING VFR CIGS AND VSBYS. SHRT WV DROPPING INTO THE UPR TROF WILL RETURN MVFR CIGS LATE TNGT AS THE WV GRABS MOISTURE OFF THE LAKES. OCNL SHRA OVER THE RME AND SYR PSBL AFT 08Z SHD NOT LIMT THE VSBYS. MVFR/VFR CIGS WILL CONT THRU THE END OF THE TAF PD WITH A CAA NW FLOW REGIME. WINDS WILL BE COME LGT TNGT...THEN NW ONCE AGAIN ON SUN WITH MIXING. MON THRU WED...MAINLY VFR. THU...MVFR IN SHRA AND TSRA. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM...MLJ LONG TERM...DGM AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
152 PM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL GRADUALLY CROSS THE REGION THIS AFTERNOON. ALTHOUGH A FEW SHOWERS WILL PRECEDE THIS SYSTEM...MUCH OF THE DAY IS EXPECTED TO BE RAIN FREE. A COOLER NORTHWEST AIR FLOW WILL FOLLOW FOR THE SECOND HALF OF THE WEEKEND...ALONG WITH A FEW HIT AND MISS SHOWERS ON SUNDAY...MAINLY OVER CENTRAL NEW YORK. && .NEAR TERM /THROUGH SUNDAY/... RADAR WAS LARGELY FREE OF ECHOES EARLY THIS AFTERNOON EXCEPT FOR A FEW VERY ISLD SHRA OCCASIONALLY POPPING UP HERE AND THERE BUT BEING SHORT-LIVED. ACVTY SEEMS TO BE A TAD MORE PREVALENT IN NE PA NR SFC FRNT WHICH EXTENDED FROM NRN CATSKILLS TO BTWN IPT AND AVP IN NE PA IN OUR FORECAST AREA. WATER VAPOR IMAGERY SHOWS SIGNIFICANT UPPER LEVEL WAVE MOVG ACRS NRN NEW ENGLAND AND SERN CANADA. THIS WAVE WAS ENHANCING STRG UPR CONFLUENCE ACRS NEW ENGLAND TO NOVA SCOTIA AND HENCE AN UPPER LEVEL JET STREAK WAS POSITIONED IN THIS AREA. ENHANCED DVRG IN THE RR QUAD OF THE JET WAS PROMOTING SOME LIFTING INTO NE PA AND ITS LOWER LEVEL AGEO FORCING WAS ALSO PUSH THE FRNT SOUTHWARD. BEST SHOT OF A FEW SHRA AND EVEN A LITTLE TSRA WILL BE MAINLY ACRS OUR FAR SE FORECAST AREA IN THE POCONOS TO SRN CATSKILLS FOR THE REST OF THE AFTERNOON DUE TO THIS DYNAMICAL FORCING. NORTH OF THE FRNT...THE CUMULUS WAS BUILDING BUT NOT TO EXTENT THAT I EARLIER THHOUGHT. THE ONLY EXCEPTION WAS OVER AREAS DIRECTLY DOWNWIND OF LAKE ONTARIO WHERE LAKE MOISTURE WAS ENHANCING LL MOISTURE AND LEADING TO DEEPER CUMULUS AND A LITTLE ISLD SHRA ACVTY AT TIMES. HENCE HAVE SOME ISLD CHC OF SHRA WELL N OF THE FRNT ACRS CNTRL NY AND NRN PA. THIS ACVTY WILL WANE SOON EXCEPT IN NC NY DOWNWIND OF LAKE ONTARIO. FOR TONIGHT...INITIALLY CUMULUS AND ISLD SHRA WILL FALL APART WITH LOSS OF INSOLATION. CONTINUED LL NW FLOW AND CAA WILL CONT ACRS THE RELATIVELY WARM WATERS OF LAKE ONTARIO. LAKE ONTARIO TEMPS WERE RUNNING ARND 20-21C AS 850 MB TEMPS DROP TO ARND 7-8C OR SO BY LATE TONIGHT. ADDTNLY ANOTHER SHRT WAVE WILL DROP SOUTHWARD OVERNIGHT REACHING SOUTHEAST ONTARIO AND WESTERN QUEBEC BY 12Z. LIFTING FROM THIS WAVE IN ASSCTN WITH LAKE MOISTURE WILL TRIGGER SHRA AGAIN LATER TONIGHT IN NC NY...WITH NO PRECIPITATION EXPECTED IN SC NY DOWN TO NE PA BEFORE 12Z. THEN FOR SUNDAY...UPPER LEVEL WAVE PASSES TO THE EAST BUT IS FOLLOWING BY AN EVEN CHILLIER SHOT OF AIR WITH 850 MB TEMPS DROPPING TO ARND 6C WHICH IS ABT A 14-15C DIFFERENTIAL. THE FLOW REMAINS ABT 310 OR SO WHICH WILL BRING LAKE MOISTURE DOWN INTO THE HILLS OF NC NY AND DOWN TO SC NY AND FAR NE PA. WITH INSOLATION AND COLD TEMPERATURES AT 850 MB I SEE ISLD TO SCT SHRA FROM NRN PA TO SC NY AND SCT SHRA INTO NC NY DIRECTLY DOWNWIND OF LAKE ONTARIO. THE ACVTY WILL WANE LATER IN THE DAY AS INSOLATION BREAKS UP ANY ORGANIZED LAKE EFFECT RAINS. HAVE SLGHT CHC IN NE PA TO LO CHC IN SC NY TO HIGH CHC IN NC NY FOR SUNDAY. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... 5 AM UPDATE... DEEPENING NW FLOW TNT-SUN...AS THE MAIN UPR LVL TROUGH AXIS SHIFTS INTO QUE...WILL ALLOW A COOLER AMS TO SPREAD INTO NY/PA. LINGERING LOW LVL MOISTURE WILL COMBINE WITH THE PASSAGE OF ANOTHER S/WV LATE TNT INTO SUN...TO BRING SCTD -SHRA ACRS OUR CNY ZNS...ALSO HELPED BY SOME UPSLOPING VIA NWLY FLOW. 925-850 MB CAA ON SUN...ALG WITH AT LEAST MRNG CLDNS/SCTD -SHRA...WILL BRING COOLER READINGS (AS MENTIONED ABV)...WITH HIGH TEMPS PERHAPS STAYING IN THE UPR 60S FOR SXNS OF THE FA (SPCLY THE HIGHER TERRAIN ACRS CNY). SUN NGT-MON NGT... A LARGE SFC HIGH WILL BUILD INTO NY/PA FROM THE UPR MIDWEST. THIS WILL LEAD TO A CLEARING AND COOL NGT SUN NGT...FOLLOWED BY PTLY-MSTLY SUNNY SKIES MON...WITH HIGHS MAINLY IN THE 70S...AS THE COOLEST PTN OF THE AMS (850 MB TEMPS OF 4-6 C AT 12Z MON) BEGINS TO SHIFT TO OUR NE INTO NRN NEW ENG. WAA MON NGT COULD WELL LEAD TO SOME INCREASE IN MID TO UPR-LVL CLDNS...BUT CONDS STILL LOOK RAIN-FREE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... 700 AM EDT UPDATE... FORECAST IS IN GOOD SHAPE. NO CHANGES NEEDED. PREVIOUS FORECAST... LATEST EXTENDED MODEL GUIDANCE CONTINUING TO SUGGEST A FAIRLY COOL PATTERN THROUGH THE TIME FRAME AS A WESTERN U.S. RIDGE DEVELOPS AND A LARGE UPPER CLOSED LOW PREVAILS ACROSS THE CANADIAN PRAIRIE PROVINCES. THIS COMBINED WITH STRONG UPPER RIDGING SOUTH OF GREENLAND WILL ENSURE A FAIRLY STAGNANT UPPER PATTERN THROUGH THE PERIOD. THAT SAID...SFC HIGH PRESSURE WILL BE IN FIRM CONTROL EARLY IN THE TIME FRAME WHICH SHOULD LEAD TO FAIRLY COOL OVERNIGHT LOWS TUE MORNING WITH LATEST GUIDANCE SUGGESTING MID TO UPPER 40S A POSSIBILITY FOR THE TRANSITIONALLY COOLER VALLEY LOCATIONS. NEXT WX FEATURE OF INTEREST SET TO ARRIVE LATE TUE/EARLY WED AS SHORTWAVE ENERGY ROTATING ALONG THE EASTERN PERIPHERY OF CENTRAL CANADIAN UPPER LOW SENDS A COLD FRONT ACROSS THE AREA. FOR NOW...HAVE CAPPED POPS IN THE CHC CATEGORY WHICH AGREES WELL WITH SURROUNDING OFFICES AND LATEST HPC GUIDANCE. FOLLOWING THIS...ANOTHER QUICK COOL DOWN IS EXPECTED BY WEEK/S END AS NEXT SURFACE HIGH PRESSURE SYSTEM SETTLES OVER THE CENTRAL/EASTERN GREAT LAKES. && .AVIATION /17Z SATURDAY THROUGH WEDNESDAY/... 700 AM EDT UPDATE... MVFR CIGS HAVE DEVELOPED ACROSS MUCH OF THE REGION THIS MORNING. AS THE MORNING PROGRESSES...MVFR CIGS WILL LIFT TO VFR. DRY AIR IS FUNNELING INTO THE REGION FROM THE NORTHWEST AND WILL CONTINUE TO THROUGH THE AFTERNOON... THUS CLOUDS WILL SLOWLY DIMINISH BY LATE EVENING AND THE CHANCE FOR RAIN WILL BE MINIMAL. AN ISOLATED SHOWER MAY DEVELOP BUT CHANCES ARE LOW THEREFORE DECIDED TO KEEP OUT OF TAFS. SATURDAY NIGHT AS WINDS REMAIN FROM THE WEST AND MOVE ACROSS THE LAKES... IFR CIGS SHOULD DEVELOP ACROSS THE AREA. SUN THRU WED...MAINLY VFR...HOWEVER ISOLATED MVFR IN DAILY SHWRS DURING THE AFTERNOON HRS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM...MLJ LONG TERM...DGM AVIATION...KAH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
155 PM EDT SAT AUG 3 2013 .SYNOPSIS... SEVERAL SHORTWAVE TROUGHS ACROSS CENTRAL NORTH CAROLINA WILL YIELD UNSETTLED WEATHER THROUGH THE EVENING BEFORE A STRONGER COLD FRONT APPROACHES FROM THE NORTH ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 955 AM SATURDAY... UPDATE: EARLIER SHOWERS IN THE SOUTHEAST HAVE ENDED AND LIGHT SHOWER ACTIVITY HAS FORMED ON A SECONDARY BOUNDARY ACROSS THE NORTHWEST PIEDMONT. BASED ON SURFACE ANALYSIS IT DOES APPEAR THAT THE ORIGINAL BOUNDARY HAS WASHED OUT A BIT BUT IS POISED TO MAKE A COMEBACK LATER THIS AFTERNOON AS A SMALL SHEAR AXIS EXISTS BETWEEN THE SANDHILLS AND COASTAL PLAIN AND THIS COULD BE A FOCUS FOR SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON. THEREFORE HAVE REMOVED POPS IN THE SOUTHEAST THIS MORNING AND REPLACED THEM WITH SLIGHT CHANCE IN THE NORTHERN TIER. HAVE LEFT POPS IN THE SOUTHEAST FOR THIS AFTERNOON. AS FAR AS TEMPERATURES ARE CONCERNED STILL GOING WITH A HIGH NEAR 90 BUT SUB-VFR CEILINGS HAVE HELD ON LONGER THAN ANTICIPATED WHICH MAY AFFECT TEMPERATURES BUT AFTER THE CEILINGS BREAK THERE SHOULD STILL BE ENOUGH INSOLATION TO HELP TEMPERATURES QUICKLY RECOVER. PREVIOUS DISCUSSION FOLLOWS. - ELLIS LINGERING...WEAK SURFACE BOUNDARY REMAINS OVER CENTRAL NORTH CAROLINA...AND IN VICINITY OF THE BOUNDARY AND THE INSTABILITY GRADIENT NOTED ON THE SPC MESOANALYSIS...ISOLATED SHOWERS CONTINUED EARLY THIS MORNING. THE 00Z UPPER-AIR ANALYSIS ALSO SHOWED A PARADE OF 700MB SHORTWAVES MOVING TOWARD THE AREA IN THE NORTHWEST FLOW ALOFT...AND THE LATEST HRRR WRF NOTES A FEW SHOWERS LINGERING THROUGH DAWN IN CENTRAL NORTH CAROLINA. FOLLOWING THIS...THE 850MB THETA-E RIDGE PERSISTS OVER CENTRAL NORTH CAROLINA THROUGHOUT THE DAY IN VICINITY OF THE REMNANT BOUNDARY. ALTHOUGH JET SUPPORT IS WELL NORTH AND NORTHWEST AND OVERALL LIFT IS FORECAST TO BE MODEST AT BEST ON THE GFS...INSTABILITY OF AROUND 1500J/KG DURING THE AFTERNOON SHOULD BE ENOUGH TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS PER A BLEND OF THE MAV AND MET MOS GUIDANCE...AND THE CONSENSUS OF THE HIGH-RESOLUTION MODEL OUTPUT. THE CONSENSUS OF THAT OUTPUT CERTAINLY PLACES THE HIGHER POTENTIAL FOR SCATTERED SHOWERS AND THUNDERSTORMS IN VICINITY OF INTERSTATE 95...AND WILL SHOW THE HIGHER CHANCES THERE FOR TODAY RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA...AGAIN CLOSER TO THE REMNANT BOUNDARY AND IN DEEPER MOISTURE. IF THERE WAS FORECAST STRONGER LOW-LEVEL CONVERGENCE... SHEAR...OR DIFFLUENCE ALOFT THERE MAY BE MORE CONFIDENCE IN NOTING THE POTENTIAL FOR A LOCALLY SEVERE STORM IN THE HWO...BUT THESE PARAMETERS ARE FORECAST TO BE SOMEWHAT WEAK ON THE GFS...THOUGH THE 0-3KM SHEAR APPROACHING 25KT IS BETTER THAN WHAT HAS BEEN NOTED IN RECENT DAYS. WILL LIKELY NOTE THE POTENTIAL FOR A STRONG STORM IN THE OUTLOOK...KEEPING IN MIND AN ISOLATED SEVERE STORM OR TWO CANNOT BE COMPLETELY RULED OUT. OVERNIGHT...A MAXIMUM OF INSTABILITY FORECAST BY THE GFS WEST OF THE YADKIN RIVER...IN ADVANCE OF AN INCREASE IN POTENTIAL VORTICITY ON THE 1.5 PVU SURFACE LATE THIS AFTERNOON AND THIS EVENING...MAY HELP PROVIDE FOR SCATTERED SHOWERS AND THUNDERSTORMS MOVING INTO CENTRAL NORTH CAROLINA FROM THE WEST...AND LINGERING INTO THE OVERNIGHT HOURS EAST OF U.S. 1 AND INTO THE INTERSTATE 95 CORRIDOR. HIGHS TODAY AROUND 90 MOST LOCATIONS WITH PARTLY SUNNY CONDITIONS ON AVERAGE. OVERNIGHT LOWS TONIGHT UPPER 60S TO MID 70S NORTH TO SOUTH.-DJF && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 305 AM SATURDAY... A COLD FRONT APPROACHES FROM THE NORTH AND MOVES THROUGH CENTRAL NORTH CAROLINA DURING THE DAY SUNDAY. IN ADVANCE OF WHAT APPEARS TO BE THE TRUE FRONT...WINDS SHOULD VEER NORTHWEST THEN BECOME MORE TRUE NORTH OR NORTH-NORTHEAST BEHIND THE FRONT. THE 850MB FRONT LINGERS AND IS NOT FORECAST BY THE GFS TO MOVE THROUGH CENTRAL NORTH CAROLINA UNTIL THE EARLY AFTERNOON. THETA-E RIDGING AT 850MB SHIFTS SOUTH ALONG WITH HIGHER VALUES OF K INDICES...AND BY AFTERNOON THE BEST UPPER-LEVEL DIVERGENCE IS FORECAST SOUTH OF THE STATE ACROSS SOUTH CAROLINA...WHERE THE GFS IS FAIRLY AMPLE WITH THAT PARAMETER DURING THE AFTERNOON. BUFR SOUNDINGS SHOW INCREASING STABILITY... ALTHOUGH THE GFS BUFR SOUNDINGS AT KFAY AND KRWI ARE CLOSER TO THE MOIST ADIABAT IN THE TEMPERATURE PROFILE INTO SUNDAY AFTERNOON. BESIDES THE POTENTIAL FOR AN ISOLATED SHOWER SUNDAY MORNING...IT MAY BE DIFFICULT TO GET ANY PRECIPITATION ALONG AND NORTH OF U.S. 64 SUNDAY. CLOSER TO THE SOUTH CAROLINA BORDER...UNTIL THE 850MB FRONT GOES THROUGH WITH ITS ASSOCIATED LIFT...AND WHILE DEW POINTS ARE STILL AT LEAST IN THE MID 60S...AN ISOLATED-TO-SCATTERED SHOWER OR STORM REMAINS POSSIBLE. MLCAPE IN THE LOWEST KM IS HIGHER THERE THAN ELSEWHERE...AND DCAPE IS AT LEAST 1000J/KG IN THE FAR SOUTH SUNDAY...WITH INCREASING SHEAR MAKING A STRONG STORM POSSIBLE THERE IF ONE CAN DEVELOP. BY SUNSET...THIS POTENTIAL SHOULD BE LOCATED SOUTH OF CENTRAL NORTH CAROLINA ALTOGETHER. AFTER HIGHS SUNDAY FROM THE UPPER 80S TO LOWER 90S...OVERNIGHT LOWS IN THE DRIER AIR SHOULD BE IN THE 60S...APPROACHING 60 ESPECIALLY NORTH OF U.S. 64. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 155 PM SATURDAY... MONDAY... A COLD FRONT PASSING TO THE SOUTH OF THE AREA WILL GIVE WAY TO A PLEASANT DAY ON MONDAY WITH HIGH PRESSURE EDGING INTO NC FROM THE NORTH. A SHOT OF LOWER DEWPOINTS IN THE UPPER 50S AND LOWER 60S WILL LIMIT INSTABILITY AND THE FORECAST WILL BE DRY. THE UPPER LEVEL FLOW WILL REMAIN NORTHWESTERLY CYCLONIC FLOW PERSISTS OVER EASTERN CANADA. MODELS INDICATE SOME CIRRUS MAY SPILL INTO WESTERN NC LATE IN THE DAY AHEAD OF CONVECTION OVER THE MIDWEST. HIGHS WILL BE BELOW NORMAL IN THE MID AND UPPER 80S. MONDAY NIGHT THROUGH TUESDAY NIGHT... THE PROGRESSIVE HIGH PRESSURE JUST TO OUR NORTH WILL MOVE QUICKLY OFFSHORE...MAINTAINING SOME INFLUENCE OVER THE NORTHEASTERN CWA WHILE ALLOWING RETURN FLOW TO DEVELOP OVER THE WEST BY MONDAY NIGHT. THIS INCREASING MOISTURE COMBINED WITH THE POTENTIAL FOR A DISTURBANCE UPSTREAM TO ADVECT SOUTHEAST ACROSS THE APPALACHIANS MAY LEAD TO SHOWERS/STORMS OVER THE WESTERN PORTION OF THE CWA LATE MONDAY NIGHT...CONTINUING INTO TUESDAY. CONFIDENCE IN COVERAGE IS LOW AT THIS TIME DUE TO UNCERTAINTY IN NORTHWEST FLOW PATTERNS...BUT THERE IS ENOUGH MODEL AGREEMENT FOR AT LEAST A SLIGHT CHANCE OVER THE NORTHWEST PIEDMONT MONDAY NIGHT...WITH A SOLID CHANCE ON TUESDAY. LOWS ON MONDAY NIGHT SHOULD RANGE FROM THE MID/UPPER 60S IN THE SOUTH AND WEST TO LOWER 60S IN THE NORTHEAST. HIGHS TUESDAY IN THE LOW TO MID 80S. WEDNESDAY THROUGH SATURDAY... MOIST SOUTHERLY FLOW WILL DOMINATE IN THE LOW LEVELS FOR THE LATER HALF OF THE WEEK..WHILE THE UPPER LEVEL FLOW FLATTENS OUT A BIT IN RESPONSE TO THE UPPER LEVEL RIDGE BUILDING FROM THE SOUTHERN PLAIN ACROSS THE DEEP SOUTH. PRECIP CHANCES SHOULD BE MOSTLY CLIMATOLOGICAL WEDNESDAY AND THURSDAY WITH DIURNAL SHOWERS AND STORMS FAVORED SLIGHTLY OVER THE WEST. BY THE END OF THE WEEK...A SLOW MOVING COLD FRONT...ATTENDANT TO AN UPPER-LEVEL LOW OVER THE NORTHERN GREAT LAKES...WILL SLIP SOUTHEAST INTO OUT REGION. BASED ON CURRENT MODEL PROJECTIONS...THE DYNAMIC FORCING AND MOISTURE WILL BE LIMITED...AND THE FRONT MAY HAVE A HARD TIME MAKING IT ALL THE WAY THROUGH NC. NONETHELESS...THERE SHOULD BE A PERIOD OF HIGHER THAN NORMAL POPS BETWEEN LATE FRIDAY AND SATURDAY. HIGHS MOSTLY IN THE MID AND UPPER 80S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 130 PM SATURDAY... 24 HOUR TAF PERIOD: A FEW MVFR CEILINGS HANGING ON OUT THERE BUT CONDITIONS HAVE GONE LARGELY VFR. EASTERN TERMINALS INCLUDING KRDU WILL BE AT GREATER RISK FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON COMPARED TO KINT AND KGSO. LOCALIZED HEAVY RAIN AND ISOLATED SEVERE STORMS ARE POSSIBLE WITH WIND THE PRIMARY THREAT. A MORE PROMINENT BOUNDARY SETTING UP FROM SOUTHWEST TO NORTHEAST NEAR THE I-95 CORRIDOR WILL MAKE KFAY AND KRWI THE MOST LIKELY PLACE FOR STORMS THIS AFTERNOON..ESPECIALLY AS THE SEA BREEZE BEGINS TO INTERACT WITH THIS BOUNDARY. OTHERWISE EXPECT SOUTHWESTERLY WINDS AT 5-10 KNOTS THROUGH THE AFTERNOON INTO THE EVENING. OVERNIGHT THERE WILL ONCE AGAIN BE A CHANCE FOR FOG AND LOW STRATUS AT MOST LOCATIONS WITH MVFR VISIBILITIES AND/OR IFR CEILINGS THE MOST LIKELY IMPACTS. FOR SUNDAY A FRONT WILL CROSS THE AREA FROM NORTH TO SOUTH AND WINDS WILL BECOME NORTHERLY NEAR 10 KNOTS AFTER FRONTAL PASSAGE WITH SOME GUSTS TO 15 KNOTS EXPECTED IN THE AFTERNOON. SCATTERED TO BROKEN CEILINGS NEAR 7 KFT SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD. LONG TERM: MONDAY SHOULD SEE VFR CONDITIONS PREVAIL WITH INCREASING CHANCES FOR CONVECTION AND SUB-VFR CONDITIONS THROUGH MIDWEEK BEFORE A WEAK FRONT APPROACHES FOR THE END OF THE WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ELLIS NEAR TERM...ELLIS/DJF SHORT TERM...DJF LONG TERM...SMITH AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
135 PM EDT SAT AUG 3 2013 .SYNOPSIS... SEVERAL SHORTWAVE TROUGHS ACROSS CENTRAL NORTH CAROLINA WILL YIELD UNSETTLED WEATHER THROUGH THE EVENING BEFORE A STRONGER COLD FRONT APPROACHES FROM THE NORTH ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 955 AM SATURDAY... UPDATE: EARLIER SHOWERS IN THE SOUTHEAST HAVE ENDED AND LIGHT SHOWER ACTIVITY HAS FORMED ON A SECONDARY BOUNDARY ACROSS THE NORTHWEST PIEDMONT. BASED ON SURFACE ANALYSIS IT DOES APPEAR THAT THE ORIGINAL BOUNDARY HAS WASHED OUT A BIT BUT IS POISED TO MAKE A COMEBACK LATER THIS AFTERNOON AS A SMALL SHEAR AXIS EXISTS BETWEEN THE SANDHILLS AND COASTAL PLAIN AND THIS COULD BE A FOCUS FOR SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON. THEREFORE HAVE REMOVED POPS IN THE SOUTHEAST THIS MORNING AND REPLACED THEM WITH SLIGHT CHANCE IN THE NORTHERN TIER. HAVE LEFT POPS IN THE SOUTHEAST FOR THIS AFTERNOON. AS FAR AS TEMPERATURES ARE CONCERNED STILL GOING WITH A HIGH NEAR 90 BUT SUB-VFR CEILINGS HAVE HELD ON LONGER THAN ANTICIPATED WHICH MAY AFFECT TEMPERATURES BUT AFTER THE CEILINGS BREAK THERE SHOULD STILL BE ENOUGH INSOLATION TO HELP TEMPERATURES QUICKLY RECOVER. PREVIOUS DISCUSSION FOLLOWS. - ELLIS LINGERING...WEAK SURFACE BOUNDARY REMAINS OVER CENTRAL NORTH CAROLINA...AND IN VICINITY OF THE BOUNDARY AND THE INSTABILITY GRADIENT NOTED ON THE SPC MESOANALYSIS...ISOLATED SHOWERS CONTINUED EARLY THIS MORNING. THE 00Z UPPER-AIR ANALYSIS ALSO SHOWED A PARADE OF 700MB SHORTWAVES MOVING TOWARD THE AREA IN THE NORTHWEST FLOW ALOFT...AND THE LATEST HRRR WRF NOTES A FEW SHOWERS LINGERING THROUGH DAWN IN CENTRAL NORTH CAROLINA. FOLLOWING THIS...THE 850MB THETA-E RIDGE PERSISTS OVER CENTRAL NORTH CAROLINA THROUGHOUT THE DAY IN VICINITY OF THE REMNANT BOUNDARY. ALTHOUGH JET SUPPORT IS WELL NORTH AND NORTHWEST AND OVERALL LIFT IS FORECAST TO BE MODEST AT BEST ON THE GFS...INSTABILITY OF AROUND 1500J/KG DURING THE AFTERNOON SHOULD BE ENOUGH TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS PER A BLEND OF THE MAV AND MET MOS GUIDANCE...AND THE CONSENSUS OF THE HIGH-RESOLUTION MODEL OUTPUT. THE CONSENSUS OF THAT OUTPUT CERTAINLY PLACES THE HIGHER POTENTIAL FOR SCATTERED SHOWERS AND THUNDERSTORMS IN VICINITY OF INTERSTATE 95...AND WILL SHOW THE HIGHER CHANCES THERE FOR TODAY RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA...AGAIN CLOSER TO THE REMNANT BOUNDARY AND IN DEEPER MOISTURE. IF THERE WAS FORECAST STRONGER LOW-LEVEL CONVERGENCE... SHEAR...OR DIFFLUENCE ALOFT THERE MAY BE MORE CONFIDENCE IN NOTING THE POTENTIAL FOR A LOCALLY SEVERE STORM IN THE HWO...BUT THESE PARAMETERS ARE FORECAST TO BE SOMEWHAT WEAK ON THE GFS...THOUGH THE 0-3KM SHEAR APPROACHING 25KT IS BETTER THAN WHAT HAS BEEN NOTED IN RECENT DAYS. WILL LIKELY NOTE THE POTENTIAL FOR A STRONG STORM IN THE OUTLOOK...KEEPING IN MIND AN ISOLATED SEVERE STORM OR TWO CANNOT BE COMPLETELY RULED OUT. OVERNIGHT...A MAXIMUM OF INSTABILITY FORECAST BY THE GFS WEST OF THE YADKIN RIVER...IN ADVANCE OF AN INCREASE IN POTENTIAL VORTICITY ON THE 1.5 PVU SURFACE LATE THIS AFTERNOON AND THIS EVENING...MAY HELP PROVIDE FOR SCATTERED SHOWERS AND THUNDERSTORMS MOVING INTO CENTRAL NORTH CAROLINA FROM THE WEST...AND LINGERING INTO THE OVERNIGHT HOURS EAST OF U.S. 1 AND INTO THE INTERSTATE 95 CORRIDOR. HIGHS TODAY AROUND 90 MOST LOCATIONS WITH PARTLY SUNNY CONDITIONS ON AVERAGE. OVERNIGHT LOWS TONIGHT UPPER 60S TO MID 70S NORTH TO SOUTH.-DJF && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 305 AM SATURDAY... A COLD FRONT APPROACHES FROM THE NORTH AND MOVES THROUGH CENTRAL NORTH CAROLINA DURING THE DAY SUNDAY. IN ADVANCE OF WHAT APPEARS TO BE THE TRUE FRONT...WINDS SHOULD VEER NORTHWEST THEN BECOME MORE TRUE NORTH OR NORTH-NORTHEAST BEHIND THE FRONT. THE 850MB FRONT LINGERS AND IS NOT FORECAST BY THE GFS TO MOVE THROUGH CENTRAL NORTH CAROLINA UNTIL THE EARLY AFTERNOON. THETA-E RIDGING AT 850MB SHIFTS SOUTH ALONG WITH HIGHER VALUES OF K INDICES...AND BY AFTERNOON THE BEST UPPER-LEVEL DIVERGENCE IS FORECAST SOUTH OF THE STATE ACROSS SOUTH CAROLINA...WHERE THE GFS IS FAIRLY AMPLE WITH THAT PARAMETER DURING THE AFTERNOON. BUFR SOUNDINGS SHOW INCREASING STABILITY... ALTHOUGH THE GFS BUFR SOUNDINGS AT KFAY AND KRWI ARE CLOSER TO THE MOIST ADIABAT IN THE TEMPERATURE PROFILE INTO SUNDAY AFTERNOON. BESIDES THE POTENTIAL FOR AN ISOLATED SHOWER SUNDAY MORNING...IT MAY BE DIFFICULT TO GET ANY PRECIPITATION ALONG AND NORTH OF U.S. 64 SUNDAY. CLOSER TO THE SOUTH CAROLINA BORDER...UNTIL THE 850MB FRONT GOES THROUGH WITH ITS ASSOCIATED LIFT...AND WHILE DEW POINTS ARE STILL AT LEAST IN THE MID 60S...AN ISOLATED-TO-SCATTERED SHOWER OR STORM REMAINS POSSIBLE. MLCAPE IN THE LOWEST KM IS HIGHER THERE THAN ELSEWHERE...AND DCAPE IS AT LEAST 1000J/KG IN THE FAR SOUTH SUNDAY...WITH INCREASING SHEAR MAKING A STRONG STORM POSSIBLE THERE IF ONE CAN DEVELOP. BY SUNSET...THIS POTENTIAL SHOULD BE LOCATED SOUTH OF CENTRAL NORTH CAROLINA ALTOGETHER. AFTER HIGHS SUNDAY FROM THE UPPER 80S TO LOWER 90S...OVERNIGHT LOWS IN THE DRIER AIR SHOULD BE IN THE 60S...APPROACHING 60 ESPECIALLY NORTH OF U.S. 64. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 255 AM SATURDAY... HIGH PRESSURE WILL MOVE ACROSS THE MID ATLANTIC REGION ON MONDAY... MOVING OFFSHORE BY 00Z TUE AS A MID LEVEL SHORT WAVE EMBEDDED IN THE NW FLOW MOVES SE ACROSS THE MIDWEST. A DRY AIRMASS OVER THE STATE EARLY MONDAY...PER FORECAST SOUNDINGS WHICH SHOW PWAT JUST BELOW ONE INCH...WILL QUICKLY MODIFY AS THE DAY PROGRESSES AND THE HIGH MOVES OFFSHORE. PWAT ON THESE SAME FORECAST SOUNDINGS ARE SHOWN TO INCREASE TO AROUND 1.5 INCHES BY 03Z TUE. EVEN WITH INCREASING MOISTURE...WILL KEEP THE FORECAST DRY ON MONDAY DUE TO VERY LIMITED SYNOP SCALE AND LOW LEVEL FORCING. THE AFOREMENTIONED SHORT WAVE IS PROGGED TO CROSS THE MOUNTAINS MONDAY NIGHT AND MOVE ACROSS MID ATLANTIC AND CAROLINAS ON TUESDAY. THE COMBINATION OF INCREASING MOISTURE AND SYNOPTIC SCALE FORCING WITH THE SHORT WAVE WILL BRING INCREASED RAIN CHANCES TO THE AREA LATE MONDAY NIGHT ACROSS OUR WESTERN ZONES...AND TUESDAY ACROSS ALL OF CENTRAL NC. DURING THE MID-WEEK PERIOD...THE WESTERLIES WILL SHIFT NORTH WITH A WEAK RIDGE BECOMING ESTABLISHED ACROSS OUR AREA. THIS PATTERN WILL RESULT IN A MORE TYPICAL SUMMERTIME PATTERN WITH ISOLATED TO SCATTERED AFTERNOON/EVENING SHOWERS AND TSTMS. BY LATE WEEK...THE NEXT SHORT WAVE AND COLD FRONT WILL APPROACH FROM THE NW...THUS LOOK FOR INCREASING RAIN CHANCES ESP LATE ON FRIDAY. THIS SOLUTION IS SLIGHTLY LATER IN TIMING THAN EARLIER MODEL RUNS...WHICH BROUGHT THIS SAME SYSTEM IN AS EARLY AS LATE THURSDAY. TEMPS DURING THE LONG TERM: A FEW DEGREES BELOW NORMAL TO START OFF THE WEEK (LOWS IN THE MID 60S AND HIGHS IN THE MID-UPPER 80S) AS LOW LEVEL THICKNESSES DECREASE IN THE WAKE OF THE TROUGH PASSAGE. THEN TEMPERATURES WILL REBOUND TO NORMAL (LOWS IN THE UPPER 60S TO NEAR 70 AND HIGHS IN THE UPPER 80S TO NEAR 90) DURING THE MID-LATE WEEK PERIOD AS THE RIDGE BUILDS OVER THE REGION. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 130 PM SATURDAY... 24 HOUR TAF PERIOD: A FEW MVFR CEILINGS HANGING ON OUT THERE BUT CONDITIONS HAVE GONE LAREGELY VFR. EASTERN TERMINALS INCLUDING KRDU WILL BE AT GREATER RISK FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON COMPARED TO KINT AND KGSO. LOCALIZED HEAVY RAIN AND ISOLATED SEVERE STORMS ARE POSSIBLE WITH WIND THE PRIMARY THREAT. A MORE PROMINANT BOUNDARY SETTING UP FROM SOUTHWEST TO NORTHEAST NEAR THE I-95 CORRIDOR WILL MAKE KFAY AND KRWI THE MOST LIKELY PLACE FOR STORMS THIS AFTERNOON..ESPECIALLY AS THE SEA BREEZE BEGINS TO INTERACT WITH THIS BOUNDARY. OTHERWISE EXPECT SOUTHWESTERLY WINDS AT 5-10 KNOTS THROUGH THE AFTERNOON INTO THE EVENING. OVERNIGHT THERE WILL ONCE AGAIN BE A CHANCE FOR FOG AND LOW STRATUS AT MOST LOCATIONS WITH MVFR VISIBILITES AND/OR IFR CEILINGS THE MOST LIKELY IMPACTS. FOR SUNDAY A FRONT WILL CROSS THE AREA FROM NORTH TO SOUTH AND WINDS WILL BECOME NORTHERLY NEAR 10 KNOTS AFTER FRONTAL PASSAGE WITH SOME GUSTS TO 15 KNOTS EXPECTED IN THE AFTERNOON. SCATTERED TO BROKEN CEILINGS NEAR 7 KFT SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD. LONG TERM: MONDAY SHOULD SEE VFR CONDITIONS PREVAIL WITH INCREASING CHANCES FOR CONVECTION AND SUB-VFR CONDITIONS THROUGH MIDWEEK BEFORE A WEAK FRONT APPROACHES FOR THE END OF THE WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ELLIS NEAR TERM...ELLIS/DJF SHORT TERM...DJF LONG TERM...NP AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
958 AM EDT SAT AUG 3 2013 .SYNOPSIS... AS A WEAK FRONT LIES OVER THE AREA...ANOTHER...STRONGER COLD FRONT APPROACHES FROM THE NORTHWEST. THIS FRONT WILL PASS THROUGH THE REGION SUNDAY. HIGH PRESSURE BUILDS IN BEHIND THE FRONT MONDAY BEFORE MOVING OFF THE MID-ATLANTIC COAST TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 955 AM SATURDAY... UPDATE: EARLIER SHOWERS IN THE SOUTHEAST HAVE ENDED AND LIGHT SHOWER ACTIVITY HAS FORMED ON A SECONDARY BOUNDARY ACROSS THE NORTHWEST PIEDMONT. BASED ON SURFACE ANALYSIS IT DOES APPEAR THAT THE ORIGINAL BOUNDARY HAS WASHED OUT A BIT BUT IS POISED TO MAKE A COMEBACK LATER THIS AFTERNOON AS A SMALL SHEAR AXIS EXISTS BETWEEN THE SANDHILLS AND COASTAL PLAIN AND THIS COULD BE A FOCUS FOR SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON. THEREFORE HAVE REMOVED POPS IN THE SOUTHEAST THIS MORNING AND REPLACED THEM WITH SLIGHT CHANCE IN THE NORTHERN TIER. HAVE LEFT POPS IN THE SOUTHEAST FOR THIS AFTERNOON. AS FAR AS TEMPERATURES ARE CONCERNED STILL GOING WITH A HIGH NEAR 90 BUT SUB-VFR CEILINGS HAVE HELD ON LONGER THAN ANTICIPATED WHICH MAY AFFECT TEMPERATURES BUT AFTER THE CEILINGS BREAK THERE SHOULD STILL BE ENOUGH INSOLATION TO HELP TEMPERATURES QUICKLY RECOVER. PREVIOUS DISCUSSION FOLLOWS. - ELLIS LINGERING...WEAK SURFACE BOUNDARY REMAINS OVER CENTRAL NORTH CAROLINA...AND IN VICINITY OF THE BOUNDARY AND THE INSTABILITY GRADIENT NOTED ON THE SPC MESOANALYSIS...ISOLATED SHOWERS CONTINUED EARLY THIS MORNING. THE 00Z UPPER-AIR ANALYSIS ALSO SHOWED A PARADE OF 700MB SHORTWAVES MOVING TOWARD THE AREA IN THE NORTHWEST FLOW ALOFT...AND THE LATEST HRRR WRF NOTES A FEW SHOWERS LINGERING THROUGH DAWN IN CENTRAL NORTH CAROLINA. FOLLOWING THIS...THE 850MB THETA-E RIDGE PERSISTS OVER CENTRAL NORTH CAROLINA THROUGHOUT THE DAY IN VICINITY OF THE REMNANT BOUNDARY. ALTHOUGH JET SUPPORT IS WELL NORTH AND NORTHWEST AND OVERALL LIFT IS FORECAST TO BE MODEST AT BEST ON THE GFS...INSTABILITY OF AROUND 1500J/KG DURING THE AFTERNOON SHOULD BE ENOUGH TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS PER A BLEND OF THE MAV AND MET MOS GUIDANCE...AND THE CONSENSUS OF THE HIGH-RESOLUTION MODEL OUTPUT. THE CONSENSUS OF THAT OUTPUT CERTAINLY PLACES THE HIGHER POTENTIAL FOR SCATTERED SHOWERS AND THUNDERSTORMS IN VICINITY OF INTERSTATE 95...AND WILL SHOW THE HIGHER CHANCES THERE FOR TODAY RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA...AGAIN CLOSER TO THE REMNANT BOUNDARY AND IN DEEPER MOISTURE. IF THERE WAS FORECAST STRONGER LOW-LEVEL CONVERGENCE... SHEAR...OR DIFFLUENCE ALOFT THERE MAY BE MORE CONFIDENCE IN NOTING THE POTENTIAL FOR A LOCALLY SEVERE STORM IN THE HWO...BUT THESE PARAMETERS ARE FORECAST TO BE SOMEWHAT WEAK ON THE GFS...THOUGH THE 0-3KM SHEAR APPROACHING 25KT IS BETTER THAN WHAT HAS BEEN NOTED IN RECENT DAYS. WILL LIKELY NOTE THE POTENTIAL FOR A STRONG STORM IN THE OUTLOOK...KEEPING IN MIND AN ISOLATED SEVERE STORM OR TWO CANNOT BE COMPLETELY RULED OUT. OVERNIGHT...A MAXIMUM OF INSTABILITY FORECAST BY THE GFS WEST OF THE YADKIN RIVER...IN ADVANCE OF AN INCREASE IN POTENTIAL VORTICITY ON THE 1.5 PVU SURFACE LATE THIS AFTERNOON AND THIS EVENING...MAY HELP PROVIDE FOR SCATTERED SHOWERS AND THUNDERSTORMS MOVING INTO CENTRAL NORTH CAROLINA FROM THE WEST...AND LINGERING INTO THE OVERNIGHT HOURS EAST OF U.S. 1 AND INTO THE INTERSTATE 95 CORRIDOR. HIGHS TODAY AROUND 90 MOST LOCATIONS WITH PARTLY SUNNY CONDITIONS ON AVERAGE. OVERNIGHT LOWS TONIGHT UPPER 60S TO MID 70S NORTH TO SOUTH.-DJF && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 305 AM SATURDAY... A COLD FRONT APPROACHES FROM THE NORTH AND MOVES THROUGH CENTRAL NORTH CAROLINA DURING THE DAY SUNDAY. IN ADVANCE OF WHAT APPEARS TO BE THE TRUE FRONT...WINDS SHOULD VEER NORTHWEST THEN BECOME MORE TRUE NORTH OR NORTH-NORTHEAST BEHIND THE FRONT. THE 850MB FRONT LINGERS AND IS NOT FORECAST BY THE GFS TO MOVE THROUGH CENTRAL NORTH CAROLINA UNTIL THE EARLY AFTERNOON. THETA-E RIDGING AT 850MB SHIFTS SOUTH ALONG WITH HIGHER VALUES OF K INDICES...AND BY AFTERNOON THE BEST UPPER-LEVEL DIVERGENCE IS FORECAST SOUTH OF THE STATE ACROSS SOUTH CAROLINA...WHERE THE GFS IS FAIRLY AMPLE WITH THAT PARAMETER DURING THE AFTERNOON. BUFR SOUNDINGS SHOW INCREASING STABILITY... ALTHOUGH THE GFS BUFR SOUNDINGS AT KFAY AND KRWI ARE CLOSER TO THE MOIST ADIABAT IN THE TEMPERATURE PROFILE INTO SUNDAY AFTERNOON. BESIDES THE POTENTIAL FOR AN ISOLATED SHOWER SUNDAY MORNING...IT MAY BE DIFFICULT TO GET ANY PRECIPITATION ALONG AND NORTH OF U.S. 64 SUNDAY. CLOSER TO THE SOUTH CAROLINA BORDER...UNTIL THE 850MB FRONT GOES THROUGH WITH ITS ASSOCIATED LIFT...AND WHILE DEW POINTS ARE STILL AT LEAST IN THE MID 60S...AN ISOLATED-TO-SCATTERED SHOWER OR STORM REMAINS POSSIBLE. MLCAPE IN THE LOWEST KM IS HIGHER THERE THAN ELSEWHERE...AND DCAPE IS AT LEAST 1000J/KG IN THE FAR SOUTH SUNDAY...WITH INCREASING SHEAR MAKING A STRONG STORM POSSIBLE THERE IF ONE CAN DEVELOP. BY SUNSET...THIS POTENTIAL SHOULD BE LOCATED SOUTH OF CENTRAL NORTH CAROLINA ALTOGETHER. AFTER HIGHS SUNDAY FROM THE UPPER 80S TO LOWER 90S...OVERNIGHT LOWS IN THE DRIER AIR SHOULD BE IN THE 60S...APPROACHING 60 ESPECIALLY NORTH OF U.S. 64. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 255 AM SATURDAY... HIGH PRESSURE WILL MOVE ACROSS THE MID ATLANTIC REGION ON MONDAY... MOVING OFFSHORE BY 00Z TUE AS A MID LEVEL SHORT WAVE EMBEDDED IN THE NW FLOW MOVES SE ACROSS THE MIDWEST. A DRY AIRMASS OVER THE STATE EARLY MONDAY...PER FORECAST SOUNDINGS WHICH SHOW PWAT JUST BELOW ONE INCH...WILL QUICKLY MODIFY AS THE DAY PROGRESSES AND THE HIGH MOVES OFFSHORE. PWAT ON THESE SAME FORECAST SOUNDINGS ARE SHOWN TO INCREASE TO AROUND 1.5 INCHES BY 03Z TUE. EVEN WITH INCREASING MOISTURE...WILL KEEP THE FORECAST DRY ON MONDAY DUE TO VERY LIMITED SYNOP SCALE AND LOW LEVEL FORCING. THE AFOREMENTIONED SHORT WAVE IS PROGGED TO CROSS THE MOUNTAINS MONDAY NIGHT AND MOVE ACROSS MID ATLANTIC AND CAROLINAS ON TUESDAY. THE COMBINATION OF INCREASING MOISTURE AND SYNOPTIC SCALE FORCING WITH THE SHORT WAVE WILL BRING INCREASED RAIN CHANCES TO THE AREA LATE MONDAY NIGHT ACROSS OUR WESTERN ZONES...AND TUESDAY ACROSS ALL OF CENTRAL NC. DURING THE MID-WEEK PERIOD...THE WESTERLIES WILL SHIFT NORTH WITH A WEAK RIDGE BECOMING ESTABLISHED ACROSS OUR AREA. THIS PATTERN WILL RESULT IN A MORE TYPICAL SUMMERTIME PATTERN WITH ISOLATED TO SCATTERED AFTERNOON/EVENING SHOWERS AND TSTMS. BY LATE WEEK...THE NEXT SHORT WAVE AND COLD FRONT WILL APPROACH FROM THE NW...THUS LOOK FOR INCREASING RAIN CHANCES ESP LATE ON FRIDAY. THIS SOLUTION IS SLIGHTLY LATER IN TIMING THAN EARLIER MODEL RUNS...WHICH BROUGHT THIS SAME SYSTEM IN AS EARLY AS LATE THURSDAY. TEMPS DURING THE LONG TERM: A FEW DEGREES BELOW NORMAL TO START OFF THE WEEK (LOWS IN THE MID 60S AND HIGHS IN THE MID-UPPER 80S) AS LOW LEVEL THICKNESSES DECREASE IN THE WAKE OF THE TROUGH PASSAGE. THEN TEMPERATURES WILL REBOUND TO NORMAL (LOWS IN THE UPPER 60S TO NEAR 70 AND HIGHS IN THE UPPER 80S TO NEAR 90) DURING THE MID-LATE WEEK PERIOD AS THE RIDGE BUILDS OVER THE REGION. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 655 AM SATURDAY... VFR CONDITIONS SHOULD PREVAIL DURING THE 12Z VALID TAF PERIOD... FOLLOWING A SHORT PERIOD THROUGH MID-MORNING OF AREAS OF IFR CONDITIONS NEAR A REMNANT SURFACE FRONT OVER CENTRAL NORTH CAROLINA...AND IN VICINITY OF OVERNIGHT RAINFALL. SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND TONIGHT WOULD PRODUCE SUB-VFR CONDITIONS BUT CURRENT POINT FORECAST PROBABILITY WAS INSUFFICIENT TO INCLUDE IN A PREVAILING OR TEMPORARY MODE AT TAF SITES. WINDS WILL BE SOUTHWEST PREVAILING AT 10KT OR LESS. THESE WINDS WILL BEGIN TO VEER OVERNIGHT AS ANOTHER MORE NOTICEABLE FRONT MOVES INTO CENTRAL NORTH CAROLINA. THERE IS A CHANCE OF LOW CLOUDS TONIGHT TOWARD KFAY AND KRWI IN THE FRONTAL ZONE...BUT CURRENTLY THE UNCERTAINTY WAS SUFFICIENT TO LEAVE THESE OUT OF THE TAF EXCEPT FOR A MENTION OF FEW-SCT LOW CLOUDS AT KRWI AND KFAY LATE TONIGHT. BEYOND THE 12Z VALID TAF PERIOD...THERE IS A CHANCE OF LATE NIGHT LOW CLOUDS LINGERING THROUGH EARLY SUNDAY MORNING MAINLY TOWARD KRWI AND KFAY SUNDAY BEFORE A COLD FRONT MOVES THROUGH. THIS FRONT... MOVING THROUGH SUNDAY...WILL TURN WINDS INCREASINGLY MORE TO THE NORTH AND BRING DRIER AIR INTO CENTRAL NORTH CAROLINA. HIGH POTENTIAL OF VFR CONDITIONS UNDER HIGH PRESSURE OVERNIGHT SUNDAY INTO MONDAY...THEN MOISTURE INCREASES ONCE AGAIN BY TUESDAY... RENEWING CHANCES OF SHOWERS AND THUNDERSTORMS FOR THE MIDDLE OF THE WEEK. CHANCES OF LATE NIGHT AND EARLY MORNING LOW CLOUDS INCREASE AS WELL...WITH THE CURRENT GUIDANCE HIGHER WITH THESE TOWARD THE TRIAD WEDNESDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...ELLIS/DJF SHORT TERM...DJF LONG TERM...NP AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
655 AM EDT SAT AUG 3 2013 .SYNOPSIS... AS A WEAK FRONT LIES OVER THE AREA...ANOTHER...STRONGER COLD FRONT APPROACHES FROM THE NORTHWEST. THIS FRONT WILL PASS THROUGH THE REGION SUNDAY. HIGH PRESSURE BUILDS IN BEHIND THE FRONT MONDAY BEFORE MOVING OFF THE MID-ATLANTIC COAST TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 305 AM SATURDAY... LINGERING...WEAK SURFACE BOUNDARY REMAINS OVER CENTRAL NORTH CAROLINA...AND IN VICINITY OF THE BOUNDARY AND THE INSTABILITY GRADIENT NOTED ON THE SPC MESOANALYSIS...ISOLATED SHOWERS CONTINUED EARLY THIS MORNING. THE 00Z UPPER-AIR ANALYSIS ALSO SHOWED A PARADE OF 700MB SHORTWAVES MOVING TOWARD THE AREA IN THE NORTHWEST FLOW ALOFT...AND THE LATEST HRRR WRF NOTES A FEW SHOWERS LINGERING THROUGH DAWN IN CENTRAL NORTH CAROLINA. FOLLOWING THIS...THE 850MB THETA-E RIDGE PERSISTS OVER CENTRAL NORTH CAROLINA THROUGHOUT THE DAY IN VICINITY OF THE REMNANT BOUNDARY. ALTHOUGH JET SUPPORT IS WELL NORTH AND NORTHWEST AND OVERALL LIFT IS FORECAST TO BE MODEST AT BEST ON THE GFS...INSTABILITY OF AROUND 1500J/KG DURING THE AFTERNOON SHOULD BE ENOUGH TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS PER A BLEND OF THE MAV AND MET MOS GUIDANCE...AND THE CONSENSUS OF THE HIGH-RESOLUTION MODEL OUTPUT. THE CONSENSUS OF THAT OUTPUT CERTAINLY PLACES THE HIGHER POTENTIAL FOR SCATTERED SHOWERS AND THUNDERSTORMS IN VICINITY OF INTERSTATE 95...AND WILL SHOW THE HIGHER CHANCES THERE FOR TODAY RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA...AGAIN CLOSER TO THE REMNANT BOUNDARY AND IN DEEPER MOISTURE. IF THERE WAS FORECAST STRONGER LOW-LEVEL CONVERGENCE... SHEAR...OR DIFFLUENCE ALOFT THERE MAY BE MORE CONFIDENCE IN NOTING THE POTENTIAL FOR A LOCALLY SEVERE STORM IN THE HWO...BUT THESE PARAMETERS ARE FORECAST TO BE SOMEWHAT WEAK ON THE GFS...THOUGH THE 0-3KM SHEAR APPROACHING 25KT IS BETTER THAN WHAT HAS BEEN NOTED IN RECENT DAYS. WILL LIKELY NOTE THE POTENTIAL FOR A STRONG STORM IN THE OUTLOOK...KEEPING IN MIND AN ISOLATED SEVERE STORM OR TWO CANNOT BE COMPLETELY RULED OUT. OVERNIGHT...A MAXIMUM OF INSTABILITY FORECAST BY THE GFS WEST OF THE YADKIN RIVER...IN ADVANCE OF AN INCREASE IN POTENTIAL VORTICITY ON THE 1.5 PVU SURFACE LATE THIS AFTERNOON AND THIS EVENING...MAY HELP PROVIDE FOR SCATTERED SHOWERS AND THUNDERSTORMS MOVING INTO CENTRAL NORTH CAROLINA FROM THE WEST...AND LINGERING INTO THE OVERNIGHT HOURS EAST OF U.S. 1 AND INTO THE INTERSTATE 95 CORRIDOR. HIGHS TODAY AROUND 90 MOST LOCATIONS WITH PARTLY SUNNY CONDITIONS ON AVERAGE. OVERNIGHT LOWS TONIGHT UPPER 60S TO MID 70S NORTH TO SOUTH. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 305 AM SATURDAY... A COLD FRONT APPROACHES FROM THE NORTH AND MOVES THROUGH CENTRAL NORTH CAROLINA DURING THE DAY SUNDAY. IN ADVANCE OF WHAT APPEARS TO BE THE TRUE FRONT...WINDS SHOULD VEER NORTHWEST THEN BECOME MORE TRUE NORTH OR NORTH-NORTHEAST BEHIND THE FRONT. THE 850MB FRONT LINGERS AND IS NOT FORECAST BY THE GFS TO MOVE THROUGH CENTRAL NORTH CAROLINA UNTIL THE EARLY AFTERNOON. THETA-E RIDGING AT 850MB SHIFTS SOUTH ALONG WITH HIGHER VALUES OF K INDICES...AND BY AFTERNOON THE BEST UPPER-LEVEL DIVERGENCE IS FORECAST SOUTH OF THE STATE ACROSS SOUTH CAROLINA...WHERE THE GFS IS FAIRLY AMPLE WITH THAT PARAMETER DURING THE AFTERNOON. BUFR SOUNDINGS SHOW INCREASING STABILITY... ALTHOUGH THE GFS BUFR SOUNDINGS AT KFAY AND KRWI ARE CLOSER TO THE MOIST ADIABAT IN THE TEMPERATURE PROFILE INTO SUNDAY AFTERNOON. BESIDES THE POTENTIAL FOR AN ISOLATED SHOWER SUNDAY MORNING...IT MAY BE DIFFICULT TO GET ANY PRECIPITATION ALONG AND NORTH OF U.S. 64 SUNDAY. CLOSER TO THE SOUTH CAROLINA BORDER...UNTIL THE 850MB FRONT GOES THROUGH WITH ITS ASSOCIATED LIFT...AND WHILE DEW POINTS ARE STILL AT LEAST IN THE MID 60S...AN ISOLATED-TO-SCATTERED SHOWER OR STORM REMAINS POSSIBLE. MLCAPE IN THE LOWEST KM IS HIGHER THERE THAN ELSEWHERE...AND DCAPE IS AT LEAST 1000J/KG IN THE FAR SOUTH SUNDAY...WITH INCREASING SHEAR MAKING A STRONG STORM POSSIBLE THERE IF ONE CAN DEVELOP. BY SUNSET...THIS POTENTIAL SHOULD BE LOCATED SOUTH OF CENTRAL NORTH CAROLINA ALTOGETHER. AFTER HIGHS SUNDAY FROM THE UPPER 80S TO LOWER 90S...OVERNIGHT LOWS IN THE DRIER AIR SHOULD BE IN THE 60S...APPROACHING 60 ESPECIALLY NORTH OF U.S. 64. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 255 AM SATURDAY... HIGH PRESSURE WILL MOVE ACROSS THE MID ATLANTIC REGION ON MONDAY... MOVING OFFSHORE BY 00Z TUE AS A MID LEVEL SHORT WAVE EMBEDDED IN THE NW FLOW MOVES SE ACROSS THE MIDWEST. A DRY AIRMASS OVER THE STATE EARLY MONDAY...PER FORECAST SOUNDINGS WHICH SHOW PWAT JUST BELOW ONE INCH...WILL QUICKLY MODIFY AS THE DAY PROGRESSES AND THE HIGH MOVES OFFSHORE. PWAT ON THESE SAME FORECAST SOUNDINGS ARE SHOWN TO INCREASE TO AROUND 1.5 INCHES BY 03Z TUE. EVEN WITH INCREASING MOISTURE...WILL KEEP THE FORECAST DRY ON MONDAY DUE TO VERY LIMITED SYNOP SCALE AND LOW LEVEL FORCING. THE AFOREMENTIONED SHORT WAVE IS PROGGED TO CROSS THE MOUNTAINS MONDAY NIGHT AND MOVE ACROSS MID ATLANTIC AND CAROLINAS ON TUESDAY. THE COMBINATION OF INCREASING MOISTURE AND SYNOPTIC SCALE FORCING WITH THE SHORT WAVE WILL BRING INCREASED RAIN CHANCES TO THE AREA LATE MONDAY NIGHT ACROSS OUR WESTERN ZONES...AND TUESDAY ACROSS ALL OF CENTRAL NC. DURING THE MID-WEEK PERIOD...THE WESTERLIES WILL SHIFT NORTH WITH A WEAK RIDGE BECOMING ESTABLISHED ACROSS OUR AREA. THIS PATTERN WILL RESULT IN A MORE TYPICAL SUMMERTIME PATTERN WITH ISOLATED TO SCATTERED AFTERNOON/EVENING SHOWERS AND TSTMS. BY LATE WEEK...THE NEXT SHORT WAVE AND COLD FRONT WILL APPROACH FROM THE NW...THUS LOOK FOR INCREASING RAIN CHANCES ESP LATE ON FRIDAY. THIS SOLUTION IS SLIGHTLY LATER IN TIMING THAN EARLIER MODEL RUNS...WHICH BROUGHT THIS SAME SYSTEM IN AS EARLY AS LATE THURSDAY. TEMPS DURING THE LONG TERM: A FEW DEGREES BELOW NORMAL TO START OFF THE WEEK (LOWS IN THE MID 60S AND HIGHS IN THE MID-UPPER 80S) AS LOW LEVEL THICKNESSES DECREASE IN THE WAKE OF THE TROUGH PASSAGE. THEN TEMPERATURES WILL REBOUND TO NORMAL (LOWS IN THE UPPER 60S TO NEAR 70 AND HIGHS IN THE UPPER 80S TO NEAR 90) DURING THE MID-LATE WEEK PERIOD AS THE RIDGE BUILDS OVER THE REGION. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 655 AM SATURDAY... VFR CONDITIONS SHOULD PREVAIL DURING THE 12Z VALID TAF PERIOD... FOLLOWING A SHORT PERIOD THROUGH MID-MORNING OF AREAS OF IFR CONDITIONS NEAR A REMNANT SURFACE FRONT OVER CENTRAL NORTH CAROLINA...AND IN VICINITY OF OVERNIGHT RAINFALL. SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND TONIGHT WOULD PRODUCE SUB-VFR CONDITIONS BUT CURRENT POINT FORECAST PROBABILITY WAS INSUFFICIENT TO INCLUDE IN A PREVAILING OR TEMPORARY MODE AT TAF SITES. WINDS WILL BE SOUTHWEST PREVAILING AT 10KT OR LESS. THESE WINDS WILL BEGIN TO VEER OVERNIGHT AS ANOTHER MORE NOTICEABLE FRONT MOVES INTO CENTRAL NORTH CAROLINA. THERE IS A CHANCE OF LOW CLOUDS TONIGHT TOWARD KFAY AND KRWI IN THE FRONTAL ZONE...BUT CURRENTLY THE UNCERTAINTY WAS SUFFICIENT TO LEAVE THESE OUT OF THE TAF EXCEPT FOR A MENTION OF FEW-SCT LOW CLOUDS AT KRWI AND KFAY LATE TONIGHT. BEYOND THE 12Z VALID TAF PERIOD...THERE IS A CHANCE OF LATE NIGHT LOW CLOUDS LINGERING THROUGH EARLY SUNDAY MORNING MAINLY TOWARD KRWI AND KFAY SUNDAY BEFORE A COLD FRONT MOVES THROUGH. THIS FRONT... MOVING THROUGH SUNDAY...WILL TURN WINDS INCREASINGLY MORE TO THE NORTH AND BRING DRIER AIR INTO CENTRAL NORTH CAROLINA. HIGH POTENTIAL OF VFR CONDITIONS UNDER HIGH PRESSURE OVERNIGHT SUNDAY INTO MONDAY...THEN MOISTURE INCREASES ONCE AGAIN BY TUESDAY... RENEWING CHANCES OF SHOWERS AND THUNDERSTORMS FOR THE MIDDLE OF THE WEEK. CHANCES OF LATE NIGHT AND EARLY MORNING LOW CLOUDS INCREASE AS WELL...WITH THE CURRENT GUIDANCE HIGHER WITH THESE TOWARD THE TRIAD WEDNESDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF SHORT TERM...DJF LONG TERM...NP AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 AM EDT SAT AUG 3 2013 .SYNOPSIS... AS A WEAK FRONT LIES OVER THE AREA...ANOTHER...STRONGER COLD FRONT APPROACHES FROM THE NORTHWEST. THIS FRONT WILL PASS THROUGH THE REGION SUNDAY. HIGH PRESSURE BUILDS IN BEHIND THE FRONT MONDAY BEFORE MOVING OFF THE MID-ATLANTIC COAST TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 305 AM SATURDAY... LINGERING...WEAK SURFACE BOUNDARY REMAINS OVER CENTRAL NORTH CAROLINA...AND IN VICINITY OF THE BOUNDARY AND THE INSTABILITY GRADIENT NOTED ON THE SPC MESOANALYSIS...ISOLATED SHOWERS CONTINUED EARLY THIS MORNING. THE 00Z UPPER-AIR ANALYSIS ALSO SHOWED A PARADE OF 700MB SHORTWAVES MOVING TOWARD THE AREA IN THE NORTHWEST FLOW ALOFT...AND THE LATEST HRRR WRF NOTES A FEW SHOWERS LINGERING THROUGH DAWN IN CENTRAL NORTH CAROLINA. FOLLOWING THIS...THE 850MB THETA-E RIDGE PERSISTS OVER CENTRAL NORTH CAROLINA THROUGHOUT THE DAY IN VICINITY OF THE REMNANT BOUNDARY. ALTHOUGH JET SUPPORT IS WELL NORTH AND NORTHWEST AND OVERALL LIFT IS FORECAST TO BE MODEST AT BEST ON THE GFS...INSTABILITY OF AROUND 1500J/KG DURING THE AFTERNOON SHOULD BE ENOUGH TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS PER A BLEND OF THE MAV AND MET MOS GUIDANCE...AND THE CONSENSUS OF THE HIGH-RESOLUTION MODEL OUTPUT. THE CONSENSUS OF THAT OUTPUT CERTAINLY PLACES THE HIGHER POTENTIAL FOR SCATTERED SHOWERS AND THUNDERSTORMS IN VICINITY OF INTERSTATE 95...AND WILL SHOW THE HIGHER CHANCES THERE FOR TODAY RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA...AGAIN CLOSER TO THE REMNANT BOUNDARY AND IN DEEPER MOISTURE. IF THERE WAS FORECAST STRONGER LOW-LEVEL CONVERGENCE... SHEAR...OR DIFFLUENCE ALOFT THERE MAY BE MORE CONFIDENCE IN NOTING THE POTENTIAL FOR A LOCALLY SEVERE STORM IN THE HWO...BUT THESE PARAMETERS ARE FORECAST TO BE SOMEWHAT WEAK ON THE GFS...THOUGH THE 0-3KM SHEAR APPROACHING 25KT IS BETTER THAN WHAT HAS BEEN NOTED IN RECENT DAYS. WILL LIKELY NOTE THE POTENTIAL FOR A STRONG STORM IN THE OUTLOOK...KEEPING IN MIND AN ISOLATED SEVERE STORM OR TWO CANNOT BE COMPLETELY RULED OUT. OVERNIGHT...A MAXIMUM OF INSTABILITY FORECAST BY THE GFS WEST OF THE YADKIN RIVER...IN ADVANCE OF AN INCREASE IN POTENTIAL VORTICITY ON THE 1.5 PVU SURFACE LATE THIS AFTERNOON AND THIS EVENING...MAY HELP PROVIDE FOR SCATTERED SHOWERS AND THUNDERSTORMS MOVING INTO CENTRAL NORTH CAROLINA FROM THE WEST...AND LINGERING INTO THE OVERNIGHT HOURS EAST OF U.S. 1 AND INTO THE INTERSTATE 95 CORRIDOR. HIGHS TODAY AROUND 90 MOST LOCATIONS WITH PARTLY SUNNY CONDITIONS ON AVERAGE. OVERNIGHT LOWS TONIGHT UPPER 60S TO MID 70S NORTH TO SOUTH. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 305 AM SATURDAY... A COLD FRONT APPROACHES FROM THE NORTH AND MOVES THROUGH CENTRAL NORTH CAROLINA DURING THE DAY SUNDAY. IN ADVANCE OF WHAT APPEARS TO BE THE TRUE FRONT...WINDS SHOULD VEER NORTHWEST THEN BECOME MORE TRUE NORTH OR NORTH-NORTHEAST BEHIND THE FRONT. THE 850MB FRONT LINGERS AND IS NOT FORECAST BY THE GFS TO MOVE THROUGH CENTRAL NORTH CAROLINA UNTIL THE EARLY AFTERNOON. THETA-E RIDGING AT 850MB SHIFTS SOUTH ALONG WITH HIGHER VALUES OF K INDICES...AND BY AFTERNOON THE BEST UPPER-LEVEL DIVERGENCE IS FORECAST SOUTH OF THE STATE ACROSS SOUTH CAROLINA...WHERE THE GFS IS FAIRLY AMPLE WITH THAT PARAMETER DURING THE AFTERNOON. BUFR SOUNDINGS SHOW INCREASING STABILITY... ALTHOUGH THE GFS BUFR SOUNDINGS AT KFAY AND KRWI ARE CLOSER TO THE MOIST ADIABAT IN THE TEMPERATURE PROFILE INTO SUNDAY AFTERNOON. BESIDES THE POTENTIAL FOR AN ISOLATED SHOWER SUNDAY MORNING...IT MAY BE DIFFICULT TO GET ANY PRECIPITATION ALONG AND NORTH OF U.S. 64 SUNDAY. CLOSER TO THE SOUTH CAROLINA BORDER...UNTIL THE 850MB FRONT GOES THROUGH WITH ITS ASSOCIATED LIFT...AND WHILE DEW POINTS ARE STILL AT LEAST IN THE MID 60S...AN ISOLATED-TO-SCATTERED SHOWER OR STORM REMAINS POSSIBLE. MLCAPE IN THE LOWEST KM IS HIGHER THERE THAN ELSEWHERE...AND DCAPE IS AT LEAST 1000J/KG IN THE FAR SOUTH SUNDAY...WITH INCREASING SHEAR MAKING A STRONG STORM POSSIBLE THERE IF ONE CAN DEVELOP. BY SUNSET...THIS POTENTIAL SHOULD BE LOCATED SOUTH OF CENTRAL NORTH CAROLINA ALTOGETHER. AFTER HIGHS SUNDAY FROM THE UPPER 80S TO LOWER 90S...OVERNIGHT LOWS IN THE DRIER AIR SHOULD BE IN THE 60S...APPROACHING 60 ESPECIALLY NORTH OF U.S. 64. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 255 AM SATURDAY... HIGH PRESSURE WILL MOVE ACROSS THE MID ATLANTIC REGION ON MONDAY... MOVING OFFSHORE BY 00Z TUE AS A MID LEVEL SHORT WAVE EMBEDDED IN THE NW FLOW MOVES SE ACROSS THE MIDWEST. A DRY AIRMASS OVER THE STATE EARLY MONDAY...PER FORECAST SOUNDINGS WHICH SHOW PWAT JUST BELOW ONE INCH...WILL QUICKLY MODIFY AS THE DAY PROGRESSES AND THE HIGH MOVES OFFSHORE. PWAT ON THESE SAME FORECAST SOUNDINGS ARE SHOWN TO INCREASE TO AROUND 1.5 INCHES BY 03Z TUE. EVEN WITH INCREASING MOISTURE...WILL KEEP THE FORECAST DRY ON MONDAY DUE TO VERY LIMITED SYNOP SCALE AND LOW LEVEL FORCING. THE AFOREMENTIONED SHORT WAVE IS PROGGED TO CROSS THE MOUNTAINS MONDAY NIGHT AND MOVE ACROSS MID ATLANTIC AND CAROLINAS ON TUESDAY. THE COMBINATION OF INCREASING MOISTURE AND SYNOPTIC SCALE FORCING WITH THE SHORT WAVE WILL BRING INCREASED RAIN CHANCES TO THE AREA LATE MONDAY NIGHT ACROSS OUR WESTERN ZONES...AND TUESDAY ACROSS ALL OF CENTRAL NC. DURING THE MID-WEEK PERIOD...THE WESTERLIES WILL SHIFT NORTH WITH A WEAK RIDGE BECOMING ESTABLISHED ACROSS OUR AREA. THIS PATTERN WILL RESULT IN A MORE TYPICAL SUMMERTIME PATTERN WITH ISOLATED TO SCATTERED AFTERNOON/EVENING SHOWERS AND TSTMS. BY LATE WEEK...THE NEXT SHORT WAVE AND COLD FRONT WILL APPROACH FROM THE NW...THUS LOOK FOR INCREASING RAIN CHANCES ESP LATE ON FRIDAY. THIS SOLUTION IS SLIGHTLY LATER IN TIMING THAN EARLIER MODEL RUNS...WHICH BROUGHT THIS SAME SYSTEM IN AS EARLY AS LATE THURSDAY. TEMPS DURING THE LONG TERM: A FEW DEGREES BELOW NORMAL TO START OFF THE WEEK (LOWS IN THE MID 60S AND HIGHS IN THE MID-UPPER 80S) AS LOW LEVEL THICKNESSES DECREASE IN THE WAKE OF THE TROUGH PASSAGE. THEN TEMPERATURES WILL REBOUND TO NORMAL (LOWS IN THE UPPER 60S TO NEAR 70 AND HIGHS IN THE UPPER 80S TO NEAR 90) DURING THE MID-LATE WEEK PERIOD AS THE RIDGE BUILDS OVER THE REGION. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 215 AM SATURDAY... VFR CONDITIONS SHOULD PREVAIL DURING THE 06Z VALID TAF PERIOD. IN A MORE MOIST AIR MASS...AND FOLLOWING AREAS OF HEAVY RAIN CLOSE BY... A PERIOD OF IFR CONDITIONS ARE EXPECTED MAINLY TOWARD KFAY DURING THE EARLY MORNING HOURS. AS A BRIEF PERIOD OF CLEARING OCCURS DURING THE EARLY MORNING...VISIBILITIES COULD DROP TO AT LEAST MVFR TOWARD KRDU AND KRWI. SCATTERED SHOWERS AND THUNDERSTORMS WOULD PRODUCE SUB-VFR CONDITIONS BUT CURRENT POINT FORECAST PROBABILITY WAS INSUFFICIENT TO INCLUDE IN A PREVAILING OR TEMPORARY MODE AT TAF SITES. BEYOND THE 06Z VALID TAF PERIOD...THERE IS A CHANCE OF EARLY MORNING LOW CLOUDS MAINLY TOWARD KRWI AND KFAY SUNDAY BEFORE A COLD FRONT MOVES THROUGH. THIS FRONT...MOVING THROUGH SUNDAY...WILL TURN WINDS INCREASINGLY MORE TO THE NORTH AND BRING DRIER AIR INTO CENTRAL NORTH CAROLINA. HIGH POTENTIAL OF VFR CONDITIONS UNDER HIGH PRESSURE OVERNIGHT SUNDAY INTO MONDAY...THEN MOISTURE INCREASES ONCE AGAIN BY TUESDAY...RENEWING CHANCES OF SHOWERS AND THUNDERSTORMS FOR THE MIDDLE OF THE WEEK. CHANCES OF LATE NIGHT AND EARLY MORNING LOW CLOUDS INCREASE AS WELL...WITH THE CURRENT GUIDANCE HIGHER WITH THESE TOWARD THE TRIAD WEDNESDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF SHORT TERM...DJF LONG TERM...NP AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 AM EDT SAT AUG 3 2013 .SYNOPSIS... AS A WEAK FRONT LIES OVER THE AREA...ANOTHER...STRONGER COLD FRONT APPROACHES FROM THE NORTHWEST. THIS FRONT WILL PASS THROUGH THE REGION SUNDAY. HIGH PRESSURE BUILDS IN BEHIND THE FRONT MONDAY BEFORE MOVING OFF THE MID-ATLANTIC COAST TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10 PM FRIDAY... A WEAKENING SURFACE BOUNDARY LOCATED ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE AREA COMBINED WITH STILL SUFFICIENT INSTABILITY LATE THIS EVENING ARE SUPPORTING SHOWER AND THUNDERSTORM DEVELOPMENT OVER PORTIONS OF THE SANDHILLS AND SOUTHERN COASTAL PLAIN. THE SPC MESO PAGE IS STILL SHOWING UPWARDS OF 2000 J/KG OF MLCAPE... WITH A SLOWLY STABILIZING BOUNDARY LAYER. THE LATEST HRRR AND OTHER HI-RES MODELS SHOW THIS ACTIVITY GRADUALLY WEAKENING THIS LATE THIS INTO THE EARLY MORNING HOURS OF SATURDAY. THIS SEEMS REASONABLE. HOWEVER... A WEAK IMPULSE OR TWO MOVING THROUGH THE WEST TO WEST-NORTHWEST MID LEVEL FLOW COULD HELP A FEW ISOLATED SHOWERS DEVELOP EVEN AFTER 06Z INVOF THE WEAK FRONT. WILL SHOW A GOOD CHANCE FOR SHOWERS AND STORMS THROUGH 06Z ACROSS THE AREA MENTION ABOVE (SE)... TRANSITING TO A SLIGHT CHANCE OF STORMS AFTER 06Z (WILL ADD TO NEXT UPDATE TO FORECAST AROUND 1130-12)... WITH A DRY FORECAST ELSEWHERE. DO NOT EXPECT ANY SVR WEATHER FROM THESE SHOWERS AND STORMS... BUT LOCALIZED FLOODING MAY BE POSSIBLE... ESPECIALLY ACROSS PORTIONS OF CUMBERLAND AND NORTHERN SAMPSON COUNTIES (WHERE MODERATE TO HEAVY RAIN HAS BEEN FALLING FOR SEVERAL HOURS). EXPECT SKIES WILL AT LEAST BE PARTLY TO MOSTLY CLOUDY OVERNIGHT... WITH AT LEAST SOME MID/HIGH LEVEL DEBRIS CLOUDINESS FROM CONVECTION UPSTREAM. IN ADDITION... THINK WE CLOUD SEE SOME LOW STRATUS AND OR FOG... ESPECIALLY INVOF THE WEAK BOUNDARY. GIVEN THIS HAVE BUMPED UP LOW TEMPS BY A COUPLE OF DEGREES INTO THE UPPER 60S NW TO LOWER 70S SE. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 245 PM FRIDAY... SATURDAY... THE WEAK FRONTAL ZONE OVER SOUTHERN AND EASTERN NC WILL WASH OUT BY SATURDAY AND SOUTHERLY SURFACE FLOW WILL PREVAIL ACROSS A GOOD PORTION OF CENTRAL NC. THIS WILL ALLOW 70 DEGREE DEWPOINTS AND BETTER INSTABILITY TO CREEP BACK TO THE NORTH...ALTHOUGH NORTHWESTERLY FLOW AND STRONGER MIXING SHOULD SUPPRESS INSTABILITY SOMEWHAT OVER THE NORTHWEST AND NORTHERN PIEDMONT. MODELS SHOW A THERMALLY ENHANCE LEE TROUGH DURING THE AFTERNOON...THOUGH WITH ONLY WEAK MASS CONVERGENCE AND SUBTLE RIPPLES IN THE PREVAILING NORTHWEST FLOW ALOFT. THUS...SHOWERS AND STORMS YOU BE MOSTLY ISOLATED OUTSIDE OF THE SEABREEZE OR STORMS MOVING OFF THE HIGHER TERRAIN. SATURDAY NIGHT... A STRONG SHORTWAVE MOVING THROUGH THE LONGWAVE TROUGH WILL PUSH A MODEST COLD FRONT TOWARD OUR AREA LATE SATURDAY AND SUNDAY. HOWEVER...WESTERLY DEEP LAYER FLOW AHEAD OF THE FRONT SHOULD LIMIT MOISTURE AVAILABILITY...AND UNLESS MORE ORGANIZED CONVECTION OVER THE MID-ATLANTIC STATES SENDS OUTFLOW SOUTH THROUGH VA...MOST OF SATURDAY NIGHT APPEARS TO BE DRY. WILL INDICATE BETTER CLOUD COVER ACROSS THE NORTH...WITH LOWS IN THE UPPER 60S AND LOWER 70S. -BLS SUNDAY AND SUNDAY NIGHT... STRONG SHORTWAVE TROUGH OVER ONTARIO WILL DIVE SOUTHEAST THROUGH THE EASTERN GREAT LAKES AND AND SOUTHERN NEW ENGLAND STATES ON SUNDAY...REINFORCING THE EASTERN US TROUGH AND PAVING THE WAY FOR YET ANOTHER WELL DEFINED SYNOPTIC SURFACE COLD FRONT INTO PARTS OF THE SOUTHEAST STATES SUNDAY-SUNDAY NIGHT. OVER THE PAST 24 HOURS...NWP MODELS HAVE REALLY HONED IN WITH THE TIMING OF THE FRONT THROUGH THE AREA BETWEEN 12 TO 18Z SUNDAY. MODELS HAVE ALSO TRENDED DRIER WITH THE PASSAGE OF THE FRONT THROUGH THE CAROLINAS...OWING TO THE EARLIER/UNFAVORABLE DIURNAL TIMING...WEAKENING-NEARLY NEGLIGIBLE S/W DYNAMICS AT MORE SOUTHERN LATITUDES AS CORE OF DPVA AND H5 FALLS SLIDE OFF THE NORTHERN MID-ATLANTIC SEABOARD...AND LASTLY THE LACK OF DEEP MOISTURE TRANSPORT INTO THE AREA...ROBBED/DISRUPTED BY THE SUBDUING EFFECTS OF THE DEEP WEST-NORTHWESTERLY FLOW IN PLACE EAST OF THE MOUNTAINS. AS SUCH...EXPECT TO SEE DIMINISHING RADAR TRENDS ACROSS CENTRAL NC WITH LITTLE MORE THAN ISOLATED TO WIDELY SCATTERED SHOWERS POSSIBLE...WITH BEST CHANCE ACROSS THE SOUTH DURING THE AFTERNOON BEFORE THE FRONT SETTLES SOUTH OF THE AREA SUNDAY EVENING. IN THE CASE THAT SOME MORE ORGANIZED CONVECTION DEVELOPS...MODERATELY STRONG WESTERLIES IN THE MID LEVELS OF 40 TO 45KTS COULD SUPPORT AN ISOLATED STRONG TO SEVERE STORM. HIGHS IN THE MID 80S NORTH TO AROUND 90 SOUTH. THE NORTH-SOUTH LOW-LEVEL COOL DRY AIR ADVECTION SUNDAY NIGHT SHOULD RESULT IN A LARGER TEMPERATURE SPREAD THAN NORMAL FOR THIS TIME OF YEAR. LOWS IN THE LOWER 60S NORTH(NEAR 60 ROXBORO)TO MID/UPPER 60S SOUTH. -CBL && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 255 AM SATURDAY... HIGH PRESSURE WILL MOVE ACROSS THE MID ATLANTIC REGION ON MONDAY... MOVING OFFSHORE BY 00Z TUE AS A MID LEVEL SHORT WAVE EMBEDDED IN THE NW FLOW MOVES SE ACROSS THE MIDWEST. A DRY AIRMASS OVER THE STATE EARLY MONDAY...PER FORECAST SOUNDINGS WHICH SHOW PWAT JUST BELOW ONE INCH...WILL QUICKLY MODIFY AS THE DAY PROGRESSES AND THE HIGH MOVES OFFSHORE. PWAT ON THESE SAME FORECAST SOUNDINGS ARE SHOWN TO INCREASE TO AROUND 1.5 INCHES BY 03Z TUE. EVEN WITH INCREASING MOISTURE...WILL KEEP THE FORECAST DRY ON MONDAY DUE TO VERY LIMITED SYNOP SCALE AND LOW LEVEL FORCING. THE AFOREMENTIONED SHORT WAVE IS PROGGED TO CROSS THE MOUNTAINS MONDAY NIGHT AND MOVE ACROSS MID ATLANTIC AND CAROLINAS ON TUESDAY. THE COMBINATION OF INCREASING MOISTURE AND SYNOPTIC SCALE FORCING WITH THE SHORT WAVE WILL BRING INCREASED RAIN CHANCES TO THE AREA LATE MONDAY NIGHT ACROSS OUR WESTERN ZONES...AND TUESDAY ACROSS ALL OF CENTRAL NC. DURING THE MID-WEEK PERIOD...THE WESTERLIES WILL SHIFT NORTH WITH A WEAK RIDGE BECOMING ESTABLISHED ACROSS OUR AREA. THIS PATTERN WILL RESULT IN A MORE TYPICAL SUMMERTIME PATTERN WITH ISOLATED TO SCATTERED AFTERNOON/EVENING SHOWERS AND TSTMS. BY LATE WEEK...THE NEXT SHORT WAVE AND COLD FRONT WILL APPROACH FROM THE NW...THUS LOOK FOR INCREASING RAIN CHANCES ESP LATE ON FRIDAY. THIS SOLUTION IS SLIGHTLY LATER IN TIMING THAN EARLIER MODEL RUNS...WHICH BROUGHT THIS SAME SYSTEM IN AS EARLY AS LATE THURSDAY. TEMPS DURING THE LONG TERM: A FEW DEGREES BELOW NORMAL TO START OFF THE WEEK (LOWS IN THE MID 60S AND HIGHS IN THE MID-UPPER 80S) AS LOW LEVEL THICKNESSES DECREASE IN THE WAKE OF THE TROUGH PASSAGE. THEN TEMPERATURES WILL REBOUND TO NORMAL (LOWS IN THE UPPER 60S TO NEAR 70 AND HIGHS IN THE UPPER 80S TO NEAR 90) DURING THE MID-LATE WEEK PERIOD AS THE RIDGE BUILDS OVER THE REGION. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 215 AM SATURDAY... VFR CONDITIONS SHOULD PREVAIL DURING THE 06Z VALID TAF PERIOD. IN A MORE MOIST AIR MASS...AND FOLLOWING AREAS OF HEAVY RAIN CLOSE BY... A PERIOD OF IFR CONDITIONS ARE EXPECTED MAINLY TOWARD KFAY DURING THE EARLY MORNING HOURS. AS A BRIEF PERIOD OF CLEARING OCCURS DURING THE EARLY MORNING...VISIBILITIES COULD DROP TO AT LEAST MVFR TOWARD KRDU AND KRWI. SCATTERED SHOWERS AND THUNDERSTORMS WOULD PRODUCE SUB-VFR CONDITIONS BUT CURRENT POINT FORECAST PROBABILITY WAS INSUFFICIENT TO INCLUDE IN A PREVAILING OR TEMPORARY MODE AT TAF SITES. BEYOND THE 06Z VALID TAF PERIOD...THERE IS A CHANCE OF EARLY MORNING LOW CLOUDS MAINLY TOWARD KRWI AND KFAY SUNDAY BEFORE A COLD FRONT MOVES THROUGH. THIS FRONT...MOVING THROUGH SUNDAY...WILL TURN WINDS INCREASINGLY MORE TO THE NORTH AND BRING DRIER AIR INTO CENTRAL NORTH CAROLINA. HIGH POTENTIAL OF VFR CONDITIONS UNDER HIGH PRESSURE OVERNIGHT SUNDAY INTO MONDAY...THEN MOISTURE INCREASES ONCE AGAIN BY TUESDAY...RENEWING CHANCES OF SHOWERS AND THUNDERSTORMS FOR THE MIDDLE OF THE WEEK. CHANCES OF LATE NIGHT AND EARLY MORNING LOW CLOUDS INCREASE AS WELL...WITH THE CURRENT GUIDANCE HIGHER WITH THESE TOWARD THE TRIAD WEDNESDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...BSD SHORT TERM...BLS/CBL LONG TERM...NP AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
215 AM EDT SAT AUG 3 2013 .SYNOPSIS... AS A WEAK FRONT LIES OVER THE AREA...ANOTHER...STRONGER COLD FRONT APPROACHES FROM THE NORTHWEST. THIS FRONT WILL PASS THROUGH THE REGION SUNDAY. HIGH PRESSURE BUILDS IN BEHIND THE FRONT MONDAY BEFORE MOVING OFF THE MID-ATLANTIC COAST TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10 PM FRIDAY... A WEAKENING SURFACE BOUNDARY LOCATED ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE AREA COMBINED WITH STILL SUFFICIENT INSTABILITY LATE THIS EVENING ARE SUPPORTING SHOWER AND THUNDERSTORM DEVELOPMENT OVER PORTIONS OF THE SANDHILLS AND SOUTHERN COASTAL PLAIN. THE SPC MESO PAGE IS STILL SHOWING UPWARDS OF 2000 J/KG OF MLCAPE... WITH A SLOWLY STABILIZING BOUNDARY LAYER. THE LATEST HRRR AND OTHER HI-RES MODELS SHOW THIS ACTIVITY GRADUALLY WEAKENING THIS LATE THIS INTO THE EARLY MORNING HOURS OF SATURDAY. THIS SEEMS REASONABLE. HOWEVER... A WEAK IMPULSE OR TWO MOVING THROUGH THE WEST TO WEST-NORTHWEST MID LEVEL FLOW COULD HELP A FEW ISOLATED SHOWERS DEVELOP EVEN AFTER 06Z INVOF THE WEAK FRONT. WILL SHOW A GOOD CHANCE FOR SHOWERS AND STORMS THROUGH 06Z ACROSS THE AREA MENTION ABOVE (SE)... TRANSITING TO A SLIGHT CHANCE OF STORMS AFTER 06Z (WILL ADD TO NEXT UPDATE TO FORECAST AROUND 1130-12)... WITH A DRY FORECAST ELSEWHERE. DO NOT EXPECT ANY SVR WEATHER FROM THESE SHOWERS AND STORMS... BUT LOCALIZED FLOODING MAY BE POSSIBLE... ESPECIALLY ACROSS PORTIONS OF CUMBERLAND AND NORTHERN SAMPSON COUNTIES (WHERE MODERATE TO HEAVY RAIN HAS BEEN FALLING FOR SEVERAL HOURS). EXPECT SKIES WILL AT LEAST BE PARTLY TO MOSTLY CLOUDY OVERNIGHT... WITH AT LEAST SOME MID/HIGH LEVEL DEBRIS CLOUDINESS FROM CONVECTION UPSTREAM. IN ADDITION... THINK WE CLOUD SEE SOME LOW STRATUS AND OR FOG... ESPECIALLY INVOF THE WEAK BOUNDARY. GIVEN THIS HAVE BUMPED UP LOW TEMPS BY A COUPLE OF DEGREES INTO THE UPPER 60S NW TO LOWER 70S SE. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 245 PM FRIDAY... SATURDAY... THE WEAK FRONTAL ZONE OVER SOUTHERN AND EASTERN NC WILL WASH OUT BY SATURDAY AND SOUTHERLY SURFACE FLOW WILL PREVAIL ACROSS A GOOD PORTION OF CENTRAL NC. THIS WILL ALLOW 70 DEGREE DEWPOINTS AND BETTER INSTABILITY TO CREEP BACK TO THE NORTH...ALTHOUGH NORTHWESTERLY FLOW AND STRONGER MIXING SHOULD SUPPRESS INSTABILITY SOMEWHAT OVER THE NORTHWEST AND NORTHERN PIEDMONT. MODELS SHOW A THERMALLY ENHANCE LEE TROUGH DURING THE AFTERNOON...THOUGH WITH ONLY WEAK MASS CONVERGENCE AND SUBTLE RIPPLES IN THE PREVAILING NORTHWEST FLOW ALOFT. THUS...SHOWERS AND STORMS YOU BE MOSTLY ISOLATED OUTSIDE OF THE SEABREEZE OR STORMS MOVING OFF THE HIGHER TERRAIN. SATURDAY NIGHT... A STRONG SHORTWAVE MOVING THROUGH THE LONGWAVE TROUGH WILL PUSH A MODEST COLD FRONT TOWARD OUR AREA LATE SATURDAY AND SUNDAY. HOWEVER...WESTERLY DEEP LAYER FLOW AHEAD OF THE FRONT SHOULD LIMIT MOISTURE AVAILABILITY...AND UNLESS MORE ORGANIZED CONVECTION OVER THE MID-ATLANTIC STATES SENDS OUTFLOW SOUTH THROUGH VA...MOST OF SATURDAY NIGHT APPEARS TO BE DRY. WILL INDICATE BETTER CLOUD COVER ACROSS THE NORTH...WITH LOWS IN THE UPPER 60S AND LOWER 70S. -BLS SUNDAY AND SUNDAY NIGHT... STRONG SHORTWAVE TROUGH OVER ONTARIO WILL DIVE SOUTHEAST THROUGH THE EASTERN GREAT LAKES AND AND SOUTHERN NEW ENGLAND STATES ON SUNDAY...REINFORCING THE EASTERN US TROUGH AND PAVING THE WAY FOR YET ANOTHER WELL DEFINED SYNOPTIC SURFACE COLD FRONT INTO PARTS OF THE SOUTHEAST STATES SUNDAY-SUNDAY NIGHT. OVER THE PAST 24 HOURS...NWP MODELS HAVE REALLY HONED IN WITH THE TIMING OF THE FRONT THROUGH THE AREA BETWEEN 12 TO 18Z SUNDAY. MODELS HAVE ALSO TRENDED DRIER WITH THE PASSAGE OF THE FRONT THROUGH THE CAROLINAS...OWING TO THE EARLIER/UNFAVORABLE DIURNAL TIMING...WEAKENING-NEARLY NEGLIGIBLE S/W DYNAMICS AT MORE SOUTHERN LATITUDES AS CORE OF DPVA AND H5 FALLS SLIDE OFF THE NORTHERN MID-ATLANTIC SEABOARD...AND LASTLY THE LACK OF DEEP MOISTURE TRANSPORT INTO THE AREA...ROBBED/DISRUPTED BY THE SUBDUING EFFECTS OF THE DEEP WEST-NORTHWESTERLY FLOW IN PLACE EAST OF THE MOUNTAINS. AS SUCH...EXPECT TO SEE DIMINISHING RADAR TRENDS ACROSS CENTRAL NC WITH LITTLE MORE THAN ISOLATED TO WIDELY SCATTERED SHOWERS POSSIBLE...WITH BEST CHANCE ACROSS THE SOUTH DURING THE AFTERNOON BEFORE THE FRONT SETTLES SOUTH OF THE AREA SUNDAY EVENING. IN THE CASE THAT SOME MORE ORGANIZED CONVECTION DEVELOPS...MODERATELY STRONG WESTERLIES IN THE MID LEVELS OF 40 TO 45KTS COULD SUPPORT AN ISOLATED STRONG TO SEVERE STORM. HIGHS IN THE MID 80S NORTH TO AROUND 90 SOUTH. THE NORTH-SOUTH LOW-LEVEL COOL DRY AIR ADVECTION SUNDAY NIGHT SHOULD RESULT IN A LARGER TEMPERATURE SPREAD THAN NORMAL FOR THIS TIME OF YEAR. LOWS IN THE LOWER 60S NORTH(NEAR 60 ROXBORO)TO MID/UPPER 60S SOUTH. -CBL && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 315 PM FRIDAY... LOW-LEVEL DRY AIR FEED INTO THE AREA TO START THE WORK WEEK AS HIGH PRESSURE BUILDS ACROSS THE OHIO VALLEY. CONVECTION IS EXPECTED TO BE LARGELY SUPPRESSED TO OUR SOUTH ON MONDAY...AS S/W DISTURBANCES IN THE NW FLOW ALOFT RUNNING ATOP THE LOW-LEVEL FRONTAL ZONE SOUTH OF THE AREA COULD SUPPORT AN ORGANIZED SEVERE THREAT ACROSS THE DEEP SOUTH. ONCE THE HIGH SHIFTS OFFSHORE ON TUESDAY...RETURN FLOW WILL BRING A RETURN TO THE TYPICAL SUMMERTIME PATTERN FOR THE MID-WEEK PERIOD...WITH ISOLATED TO SCATTERED AFTERNOON/EVENING SHOWERS AND TSTMS. RAIN CHANCES WILL INCREASE TOWARD LATE IN THE WORK WEEK AS AN EASTWARD MOVING AREA OF LOW PRESSURE THROUGH GREAT LAKES AND ATTENDANT TRAILING SURFACE FRONT APPROACH THE AREA ON THURSDAY BEFORE POSSIBLY STALLING ACROSS THE REGION ON FRIDAY. ADDITIONALLY...AS IS ALWAYS THE CASE WITH NW FLOW ALOFT DURING THE SUMMER...CONVECTIVE CHANCES COULD BE AUGMENTED FURTHER BY THE TIMING OF UPSTREAM CONVECTIVELY INDUCED/HYBRID VORTICITY CENTERS INTO THE AREA. SEASONABLE TEMPERATURES ALL OF NEXT WEEK. HIGHS IN THE MID TO UPPER 80S. LOWS IN THE MID 60 TO LOWER 70S. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 215 AM SATURDAY... VFR CONDITIONS SHOULD PREVAIL DURING THE 06Z VALID TAF PERIOD. IN A MORE MOIST AIR MASS...AND FOLLOWING AREAS OF HEAVY RAIN CLOSE BY... A PERIOD OF IFR CONDITIONS ARE EXPECTED MAINLY TOWARD KFAY DURING THE EARLY MORNING HOURS. AS A BRIEF PERIOD OF CLEARING OCCURS DURING THE EARLY MORNING...VISIBILITIES COULD DROP TO AT LEAST MVFR TOWARD KRDU AND KRWI. SCATTERED SHOWERS AND THUNDERSTORMS WOULD PRODUCE SUB-VFR CONDITIONS BUT CURRENT POINT FORECAST PROBABILITY WAS INSUFFICIENT TO INCLUDE IN A PREVAILING OR TEMPORARY MODE AT TAF SITES. BEYOND THE 06Z VALID TAF PERIOD...THERE IS A CHANCE OF EARLY MORNING LOW CLOUDS MAINLY TOWARD KRWI AND KFAY SUNDAY BEFORE A COLD FRONT MOVES THROUGH. THIS FRONT...MOVING THROUGH SUNDAY...WILL TURN WINDS INCREASINGLY MORE TO THE NORTH AND BRING DRIER AIR INTO CENTRAL NORTH CAROLINA. HIGH POTENTIAL OF VFR CONDITIONS UNDER HIGH PRESSURE OVERNIGHT SUNDAY INTO MONDAY...THEN MOISTURE INCREASES ONCE AGAIN BY TUESDAY...RENEWING CHANCES OF SHOWERS AND THUNDERSTORMS FOR THE MIDDLE OF THE WEEK. CHANCES OF LATE NIGHT AND EARLY MORNING LOW CLOUDS INCREASE AS WELL...WITH THE CURRENT GUIDANCE HIGHER WITH THESE TOWARD THE TRIAD WEDNESDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...BSD SHORT TERM...BLS/CBL LONG TERM...CBL AVIATION...DJF
AREA FORECAST DISCUSSION
NWS BISMARCK ND
927 PM CDT SUN AUG 4 2013 .UPDATE... ISSUED AT 917 PM CDT SUN AUG 4 2013 UPDATE FOR EVENING/OVERNIGHT POPS. STRONG THUNDERSTORMS ACROSS THE SOUTH CENTRAL HAVE CONTINUED TO TREND DOWNWARD OVER THE PAST HOUR AS THEY MOVE INTO A LESS UNSTABLE AIRMASS. THIS TREND IS EXPECTED TO CONTINUE THROUGH LATE EVENING. CAN`T RULE OUT AN ISOLATED STORM WITH SMALL HAIL...BUT NO ADDITIONAL SEVERE WEATHER IS EXPECTED. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 330 PM CDT SUN AUG 4 2013 MAIN FORECAST PROBLEM IN THE SHORT TERM PERIOD IS THE CHANCE OF SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. MODELS HAVE BEEN HAVING A HARD TIME FIGURING OUT WHAT WILL TRANSPIRE LATE THIS AFTERNOON INTO THIS EVENING. MANY FAVORABLE FACTORS FOR CONVECTION ARE IN PLACE. STRONG UPPER LEVEL JET IS PROVIDING GOOD BULK SHEAR WITH INDIVIDUAL IMPULSES TRACKING ACROSS NORTHEAST MONTANA AND SOUTHERN SASKATCHEWAN. DEWPOINT HAVE CLIMBED INTO THE UPPER 50S TO LOWER 60S ACROSS THE AREA WITH AN INVERTED SURFACE TROUGH TRACKING SLOWLY EAST ACROSS WESTERN NORTH DAKOTA PROVIDING AN ADDITIONAL FOCUSING MECHANISM FOR CONVECTION. THE LIMITING FACTOR HAS BEEN THE EXTENSIVE CLOUD COVER PROVIDING MEAGER LOW LEVEL LAPSE RATES. 19Z KDIK LAPS SOUNDING STILL INDICATES AROUND 100 MB OF CIN TO BE OVERCOME. HOWEVER SKIES ARE BEGINNING TO CLEAR IN EASTERN MONTANA INTO WESTERN NORTH DAKOTA WITH A GOOD 3 HOURS OF HEATING BEFORE WE PASS OUR DIURNAL MAX AND CURRENTLY 1000-1500 J/KG OF CAPE AVAILABLE OVER FAR WESTERN NORTH DAKOTA. THE DIRECTIONAL SHEAR PROFILE DOES BECOME LESS FAVORABLE WITH SIGNIFICANT DRYING ALOFT TAKING PLACE BEHIND THE INVERTED TROUGH WHICH CURRENTLY LAYS OVER WESTERN NORTH DAKOTA. MESOSCALE MODELS HAVE BEEN ALL OVER THE PLACE WITH CONVECTION ACROSS WESTERN AND CENTRAL NORTH DAKOTA. ABOUT THE ONLY TREND THAT CAN BE SEEN IS THAT SUCCESSIVE RUNS HAVE BECOME LESS AND LESS OMINOUS FOR CONVECTION DEVELOPING OVER WESTERN OR CENTRAL NORTH DAKOTA THIS AFTERNOON OR THIS EVENING. WITH THIS SAID...STILL THINK THERE IS A WINDOW OF OPPORTUNITY FOR CONVECTION OVER CENTRAL NORTH DAKOTA LATE THIS AFTERNOON THROUGH LATE EVENING. THE 18Z RAP SHOWS CONVECTION TRYING TO DEVELOP OVER THE NORTH CENTRAL LATE THIS AFTERNOON...SPREADING SOUTHWEST INTO SOUTHWEST NORTH DAKOTA EARLY THIS EVENING. BUT THE STRONGEST CONVECTION REMAIN OVER THE NORTH CENTRAL INTO EASTERN NORTH DAKOTA...CLOSEST TO THE MID LEVEL SHORTWAVE TROUGH. THE 12Z WRF DID NOT HAVE A GOOD HANDLE ON CONVECTION ACROSS THE NORTH...BUT DOES DEVELOP A LINE OF CONVECTION ACROSS THE SOUTHWEST BETWEEN 21-22Z. EACH SUCCESSIVE RUN OF THE HRRR CONTINUES DEPICT WEAKER CONVECTION DEVELOPING OVER CENTRAL AND EASTERN NORTH DAKOTA THIS EVENING. SETTLED ON A 20-30 POPS OVER THE CENTRAL INTO THE SOUTHWEST LATE THIS AFTERNOON SPREADING INTO CENTRAL AND EASTERN NORTH DAKOTA TONIGHT. WILL NOT MENTION SEVERE WORDING BUT A FEW STRONG TO POSSIBLY SEVERE CELLS CAN NOT BE RULED OUT GIVEN THE STRONG SHEAR AND INCREASING CAPE. CONVECTION...IF IT DOES DEVELOP SHOULD MOVE OUT OF THE EASTERN CWA AFTER MIDNIGHT. WE THEN GET A PERIOD OF UPPER LEVEL RIDGING MONDAY AHEAD OF THE NEXT SHORTWAVE TROUGH...AND THE STRONG SHORTWAVE ASSOCIATED WITH THE RETROGRADING UPPER LEVEL LOW OVER DROPPING DOWN FROM THE HUDSON BAY. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 330 PM CDT SUN AUG 4 2013 THE NORTHERN PLAINS WILL BE UNDER NORTHWEST FLOW ALOFT MONDAY NIGHT WITH UPPER LEVEL RIDGING ACROSS THE SOUTHERN PLAINS AND DEEP LOW PRESSURE OVER THE WESTERN HUDSON BAY. WILL SEE INCREASING CHANCES OF SHOWERS/THUNDERSTORMS MONDAY EVENING WEST AND LATE MONDAY NIGHT THROUGH TUESDAY MORNING AREA WIDE AS A POTENT EMBEDDED S/WV ROTATES THROUGH THE FLOW AND INTO NORTH DAKOTA...IN ADDITION TO A SFC TROUGH/COLD FRONTAL BOUNDARY PUSHING SOUTH ACROSS THE STATE INTO TUESDAY MORNING. BY TUESDAY AFTERNOON...THE MAIN AREA OF SHOWERS/THUNDERSTORMS ASSOCIATED WITH THE COLD FRONT WILL HAVE MOVED SOUTH AND EAST OF CENTRAL NORTH DAKOTA. WILL NEED TO KEEP AN EYE ON THE SOUTHEAST DURING THE AFTERNOON FOR A STRONGER STORM WHERE MODELS PROJECT NEAR 1000 J/KG OF CAPE AND LITTLE IF ANY CIN. BY TUESDAY EVENING THE UPPER LEVEL LOW IS FORECAST TO BE BETWEEN HUDSON BAY AND LAKE WINNIPEG...MAINTAINING STRONG NORTHWEST FLOW ALOFT THROUGH THURSDAY (POSSIBLY INTO FRIDAY) WITH THE UPPER LOW REMAINING QUASI-STATIONARY. LINGERING LOW LEVEL MOISTURE COUPLED WITH EMBEDDED ENERGY IN THE FLOW ALOFT WILL MAINTAIN SOME CHANCE FOR DIURNALLY DRIVEN SHOWERS/ISOLATED THUNDERSTORMS BOTH WEDNESDAY AND THURSDAY. UPPER LOW PROPAGATES SLOWLY EAST TO OVER ONTARIO FRIDAY INTO FRIDAY NIGHT...WITH A RIDGE BUILDING INTO THE MONTANA ROCKIES. HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE DAKOTAS THURSDAY NIGHT...REMAINING IN PLACE WELL INTO THE WEEKEND. THIS WILL LEAD TO MAINLY DRY CONDITIONS AND CONTINUED BELOW NORMAL TEMPERATURES OVER MOST OF THE CWA THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 917 PM CDT SUN AUG 4 2013 TAFS UPDATED THIS EVENING FOR LATEST CONVECTIVE TRENDS. SHOWERS MAY IMPACT KJMS THROUGH LATE EVENING. MVFR CIGS AND/OR VSBYS ANTICIPATED AT KMOT/KJMS DURING THE EARLY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...RK SHORT TERM...TWH LONG TERM...NH AVIATION...RK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
645 PM CDT SUN AUG 4 2013 .UPDATE... ISSUED AT 635 PM CDT SUN AUG 4 2013 UPDATE MAINLY FOR EVENING POPS BASED ON RECENT RADAR TRENDS AND SHORT RANGE MODELS. A STRONG CLUSTER OF STORMS IS MOVING INTO THE FAR NORTHWEST AND HAS WEAKENED SOMEWHAT SINCE PRODUCING QUARTER SIZE HAIL EARLIER. ANOTHER CLUSTER FROM DICKINSON TO GLEN ULLIN HAS BEEN PRODUCING SOME SMALL HAIL AS WELL. PER THE LATEST SWOMCD...A WATCH IS NOT OUT OF THE QUESTION FOR PORTIONS OF WEST CENTRAL THROUGH SOUTH CENTRAL ND. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 330 PM CDT SUN AUG 4 2013 MAIN FORECAST PROBLEM IN THE SHORT TERM PERIOD IS THE CHANCE OF SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. MODELS HAVE BEEN HAVING A HARD TIME FIGURING OUT WHAT WILL TRANSPIRE LATE THIS AFTERNOON INTO THIS EVENING. MANY FAVORABLE FACTORS FOR CONVECTION ARE IN PLACE. STRONG UPPER LEVEL JET IS PROVIDING GOOD BULK SHEAR WITH INDIVIDUAL IMPULSES TRACKING ACROSS NORTHEAST MONTANA AND SOUTHERN SASKATCHEWAN. DEWPOINT HAVE CLIMBED INTO THE UPPER 50S TO LOWER 60S ACROSS THE AREA WITH AN INVERTED SURFACE TROUGH TRACKING SLOWLY EAST ACROSS WESTERN NORTH DAKOTA PROVIDING AN ADDITIONAL FOCUSING MECHANISM FOR CONVECTION. THE LIMITING FACTOR HAS BEEN THE EXTENSIVE CLOUD COVER PROVIDING MEAGER LOW LEVEL LAPSE RATES. 19Z KDIK LAPS SOUNDING STILL INDICATES AROUND 100 MB OF CIN TO BE OVERCOME. HOWEVER SKIES ARE BEGINNING TO CLEAR IN EASTERN MONTANA INTO WESTERN NORTH DAKOTA WITH A GOOD 3 HOURS OF HEATING BEFORE WE PASS OUR DIURNAL MAX AND CURRENTLY 1000-1500 J/KG OF CAPE AVAILABLE OVER FAR WESTERN NORTH DAKOTA. THE DIRECTIONAL SHEAR PROFILE DOES BECOME LESS FAVORABLE WITH SIGNIFICANT DRYING ALOFT TAKING PLACE BEHIND THE INVERTED TROUGH WHICH CURRENTLY LAYS OVER WESTERN NORTH DAKOTA. MESOSCALE MODELS HAVE BEEN ALL OVER THE PLACE WITH CONVECTION ACROSS WESTERN AND CENTRAL NORTH DAKOTA. ABOUT THE ONLY TREND THAT CAN BE SEEN IS THAT SUCCESSIVE RUNS HAVE BECOME LESS AND LESS OMINOUS FOR CONVECTION DEVELOPING OVER WESTERN OR CENTRAL NORTH DAKOTA THIS AFTERNOON OR THIS EVENING. WITH THIS SAID...STILL THINK THERE IS A WINDOW OF OPPORTUNITY FOR CONVECTION OVER CENTRAL NORTH DAKOTA LATE THIS AFTERNOON THROUGH LATE EVENING. THE 18Z RAP SHOWS CONVECTION TRYING TO DEVELOP OVER THE NORTH CENTRAL LATE THIS AFTERNOON...SPREADING SOUTHWEST INTO SOUTHWEST NORTH DAKOTA EARLY THIS EVENING. BUT THE STRONGEST CONVECTION REMAIN OVER THE NORTH CENTRAL INTO EASTERN NORTH DAKOTA...CLOSEST TO THE MID LEVEL SHORTWAVE TROUGH. THE 12Z WRF DID NOT HAVE A GOOD HANDLE ON CONVECTION ACROSS THE NORTH...BUT DOES DEVELOP A LINE OF CONVECTION ACROSS THE SOUTHWEST BETWEEN 21-22Z. EACH SUCCESSIVE RUN OF THE HRRR CONTINUES DEPICT WEAKER CONVECTION DEVELOPING OVER CENTRAL AND EASTERN NORTH DAKOTA THIS EVENING. SETTLED ON A 20-30 POPS OVER THE CENTRAL INTO THE SOUTHWEST LATE THIS AFTERNOON SPREADING INTO CENTRAL AND EASTERN NORTH DAKOTA TONIGHT. WILL NOT MENTION SEVERE WORDING BUT A FEW STRONG TO POSSIBLY SEVERE CELLS CAN NOT BE RULED OUT GIVEN THE STRONG SHEAR AND INCREASING CAPE. CONVECTION...IF IT DOES DEVELOP SHOULD MOVE OUT OF THE EASTERN CWA AFTER MIDNIGHT. WE THEN GET A PERIOD OF UPPER LEVEL RIDGING MONDAY AHEAD OF THE NEXT SHORTWAVE TROUGH...AND THE STRONG SHORTWAVE ASSOCIATED WITH THE RETROGRADING UPPER LEVEL LOW OVER DROPPING DOWN FROM THE HUDSON BAY. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 330 PM CDT SUN AUG 4 2013 THE NORTHERN PLAINS WILL BE UNDER NORTHWEST FLOW ALOFT MONDAY NIGHT WITH UPPER LEVEL RIDGING ACROSS THE SOUTHERN PLAINS AND DEEP LOW PRESSURE OVER THE WESTERN HUDSON BAY. WILL SEE INCREASING CHANCES OF SHOWERS/THUNDERSTORMS MONDAY EVENING WEST AND LATE MONDAY NIGHT THROUGH TUESDAY MORNING AREA WIDE AS A POTENT EMBEDDED S/WV ROTATES THROUGH THE FLOW AND INTO NORTH DAKOTA...IN ADDITION TO A SFC TROUGH/COLD FRONTAL BOUNDARY PUSHING SOUTH ACROSS THE STATE INTO TUESDAY MORNING. BY TUESDAY AFTERNOON...THE MAIN AREA OF SHOWERS/THUNDERSTORMS ASSOCIATED WITH THE COLD FRONT WILL HAVE MOVED SOUTH AND EAST OF CENTRAL NORTH DAKOTA. WILL NEED TO KEEP AN EYE ON THE SOUTHEAST DURING THE AFTERNOON FOR A STRONGER STORM WHERE MODELS PROJECT NEAR 1000 J/KG OF CAPE AND LITTLE IF ANY CIN. BY TUESDAY EVENING THE UPPER LEVEL LOW IS FORECAST TO BE BETWEEN HUDSON BAY AND LAKE WINNIPEG...MAINTAINING STRONG NORTHWEST FLOW ALOFT THROUGH THURSDAY (POSSIBLY INTO FRIDAY) WITH THE UPPER LOW REMAINING QUASI-STATIONARY. LINGERING LOW LEVEL MOISTURE COUPLED WITH EMBEDDED ENERGY IN THE FLOW ALOFT WILL MAINTAIN SOME CHANCE FOR DIURNALLY DRIVEN SHOWERS/ISOLATED THUNDERSTORMS BOTH WEDNESDAY AND THURSDAY. UPPER LOW PROPAGATES SLOWLY EAST TO OVER ONTARIO FRIDAY INTO FRIDAY NIGHT...WITH A RIDGE BUILDING INTO THE MONTANA ROCKIES. HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE DAKOTAS THURSDAY NIGHT...REMAINING IN PLACE WELL INTO THE WEEKEND. THIS WILL LEAD TO MAINLY DRY CONDITIONS AND CONTINUED BELOW NORMAL TEMPERATURES OVER MOST OF THE CWA THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 635 PM CDT SUN AUG 4 2013 UPDATED 00Z TAFS TO REFLECT CURRENT OR IMMINENT THUNDERSTORMS AT KISN/KDIK/KBIS THIS EVENING. ISOLD STORMS WILL ALSO BE POSSIBLE AT KMOT THIS EVENING...AND AT KJMS AFTER 03Z. MVFR CIGS AND/OR VSBYS ALSO EXPECTED AT KMOT/KJMS DURING THE EARLY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...RK SHORT TERM...TWH LONG TERM...NH AVIATION...RK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
321 PM CDT SAT AUG 3 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 321 PM CDT SAT AUG 3 2013 MAIN FORECAST PROBLEM IN THE SHORT TERM PERIOD WILL BE THUNDERSTORM CHANCES. CURRENTLY...ALTHOUGH NOT REAL WARM...A MOIST UNSTABLE ATMOSPHERE IS DEVELOPING ACROSS EASTERN MONTANA AND FAR WESTERN NORTH DAKOTA. A SHORTWAVE INDICATED OVER NORTH CENTRAL MONTANA IN A PROGRESSIVE BAND OF WESTERLIES HAS INITIATED CONVECTION WEST OF GLASGOW. EXPECT CONVECTION TO CONTINUE TO INCREASE IN AN AREA OF STEEPENING LAPSE RATES AND STRONG DEEP LAYER SHEAR. THE 18 UTC HRRR INDICATES DISCRETE SUPERCELLS TRACKING ACROSS EASTERN MONTANA THIS AFTERNOON AND EVENING...CLIPPING THE FAR SOUTHWEST LATE THIS EVENING. THE 12 UTC WRF AND HIRES-NMM/ARW ARE SIMILAR BUT MAYBE A BIT LATER AND TRANSITION FROM DISCRETE CELLS INTO AN MCS THAT TRACKS ACROSS THE SOUTHWEST AND FAR SOUTH CENTRAL LATE TONIGHT INTO SUNDAY MORNING. WHATEVER EVENTUALLY PANS OUT...WILL DEFINITELY BUMP UP POPS TONIGHT AND SUNDAY. HAVE INCLUDED A MENTION OF SEVERE ACROSS THE SOUTHWEST THIS EVENING. AFTER MIDNIGHT...ALTHOUGH A SEVERE STORM CANNOT BE RULED OUT...THINK WE WILL BE ON THE DOWNWARD TREND. HIGH TEMPERATURES ON SUNDAY WILL DEPEND GREATLY ON THE ONGOING CONVECTION THAT TRACKS ACROSS CENTRAL INTO EASTERN NORTH DAKOTA DURING THE DAY. UTILIZED A BLEND WITH MORE WEIGHT TOWARD RAW MODEL GUIDANCE WHICH USUALLY WORKS WELL IN A CHANGEABLE WEATHER PATTERN. THIS RESULTS IN A NICE GRADIENT FROM UPPER 60S ACROSS THE NORTH CENTRAL WHERE SHOWERS HANG ON INTO THE AFTERNOON...TO AROUND 80 OVER THE SOUTHWEST WHERE WE CLEAR OUT EARLY AND TEMPERATURES REBOUND NICELY. THE WEST WILL ALSO BEGIN TO DESTABILIZE ONCE AGAIN SUNDAY AFTERNOON...WITH A FAVORABLE SHEAR ENVIRONMENT REMAINING OVER THE AREA. WILL NOT MENTION SEVERE WORDING AT THIS TIME BUT WILL KEEP A CHANCE OF THUNDERSTORMS REMAINING ACROSS ALL OF WESTERN NORTH DAKOTA SUNDAY AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 321 PM CDT SAT AUG 3 2013 CHANCES FOR PRECIPITATION WILL DECREASE WEST TO EAST SUNDAY EVENING INTO EARLY MONDAY MORNING AS A MID LEVEL SHORTWAVE TROUGH AND AREA OF SURFACE LOW PRESSURE MOVE EAST INTO THE GREAT LAKES REGION AND SURFACE HIGH PRESSURE BUILDS ACROSS WESTERN NORTH DAKOTA. WE REMAIN IN NORTHWEST FLOW ALOFT MONDAY WITH UPPER LEVEL RIDGING ACROSS THE SOUTHERN PLAINS AND DEEP LOW PRESSURE OVER THE WESTERN HUDSON BAY. WILL SEE INCREASING CHANCES OF SHOWERS/THUNDERSTORMS LATER MONDAY WEST AND NORTH AND MONDAY NIGHT AREA WIDE AS THE UPPER LOW DRIFTS SOUTHWARD ALLOWING FOR INCREASING CYCLONIC FLOW ALOFT INTO THE NORTHERN PLAINS. MODELS ARE KEYING IN ON TWO DISTINCT MID LEVEL IMPULSES ROTATING THROUGH THE FLOW ACROSS NORTH DAKOTA...IN ADDITION TO A SFC TROUGH/COLD FRONTAL BOUNDARY PUSHING SOUTH ACROSS THE STATE INTO TUESDAY MORNING. BEST CHANCES FOR PRECIPITATION WILL BE ACROSS MY NORTH AND EAST WHERE BEST LOW LEVEL FORCING IS CURRENTLY FORECAST. BY TUESDAY AFTERNOON...THE UPPER LEVEL LOW IS FORECAST TO BE ABOUT 250-400 MILES NORTHEAST OF LAKE WINNIPEG MAINTAINING STRONG CYCLONIC FLOW ALOFT...WHICH PERSISTS THROUGH WEDNESDAY. LINGERING LOW LEVEL MOISTURE COUPLED WITH EMBEDDED ENERGY IN THE FLOW ALOFT WILL MAINTAIN SOME CHANCE FOR DIURNALLY DRIVEN SHOWERS/ISOLATED THUNDERSTORMS BOTH TUESDAY AND WEDNESDAY. HOWEVER...LOW LEVEL FORCING IS PROGGED WEAK SO WIDESPREAD PRECIPITATION IS NOT EXPECTED. IN ADDITION...MUCH COOLER CANADIAN AIR WILL FILTER INTO THE REGION TUESDAY/TUESDAY NIGHT AND WEDNESDAY (HIGHS IN THE LOW/MID 70S AND LOWS TUESDAY NIGHT LOW 50S/UPPER 40S). UPPER LOW PROPAGATES SLOWLY EAST TO OVER ONTARIO THURSDAY...THEN INTO EASTERN CANADA BY SATURDAY. HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE DAKOTAS THURSDAY AND THURSDAY NIGHT...REMAINING IN PLACE WELL INTO SATURDAY. THIS WILL LEAD TO MAINLY DRY CONDITIONS AND CONTINUED BELOW NORMAL TEMPERATURES OVER MOST OF THE CWA THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 321 PM CDT SAT AUG 3 2013 MAIN CHALLENGE FOR THE AVIATION PERIOD WILL BE SHOWER AND THUNDERSTORM ACTIVITY. THERE COULD BE A SCATTERED LATE AFTERNOON THUNDERSTORM AROUND KDIK...OTHERWISE IT LOOKS LIKE THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL ENTER THE WEST LATER THIS EVENING AND SPREAD EAST ACROSS THE AREA...APPROACHING KJMS NEAR THE END OF THE 18Z TAF PERIOD. THE ONLY SIGNIFICANT CHANGE FROM THE PREVIOUS FORECAST WAS TO DELAY THE ONSET OF THUNDER ABOUT 3-4 HOURS AT ALL TAF SITES. VFR CONDITIONS EXPECTED THIS AFTERNOON AND THIS EVENING. DID NOT INTRODUCE MVFR CEILINGS TONIGHT OR SUNDAY MORNING BUT CERTAINLY COULD SEE AREAS OF MVFR CIGS/VSBYS IN THE VICINITY OF SHOWERS AND ISOLATED THUNDERSTORMS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TWH LONG TERM...NH AVIATION...TWH
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1121 PM EDT SUN AUG 4 2013 .SYNOPSIS... A BELT OF FAST WNW FLOW ALOFT WILL EXTEND FROM THE DAKOTAS TO THE MID-ATLANTIC COAST THROUGH THE MIDDLE OF THE WEEK...AS THE DEEP TROUGH OVER THE NORTHEAST SLIDES OFFSHORE AND PIVOTS AROUND A LARGE VORTEX MOVING SOUTHWEST FROM HUDSON BAY INTO SOUTH-CENTRAL CANADA. UPPER LEVEL HEIGHTS SHOULD RISE DURING THE SECOND HALF OF THE WEEK AS THE MID-LEVEL FLOW SHIFTS TO THE WEST-SOUTHWEST. AT THE SURFACE...HIGH PRESSURE OVER LK MICHIGAN THIS EVENING WILL MIGRATE OVER PENNSYLVANIA ON MONDAY BEFORE SLIDING OFF THE COAST MONDAY NIGHT. INCREASING MOISTURE IN ADVANCE OF A PLAINS/MIDWEST FRONTAL SYSTEM WILL BRING PERIODS RAIN FROM TUESDAY THROUGH THE END OF THE WEEK. BELOW NORMAL TEMPERATURES WILL MODERATE THROUGH THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... STAGE IS SET FOR A VERY COOL NIGHT /FOR EARLY AUGUST/ ACROSS CENTRAL PA...AS NEGATIVE PWAT AND 8H TEMPS ANOMALIES ON THE ORDER OF -2SD WILL ACCOMPANY SFC HIGH BUILDING OVR THE STATE. KCLE RADAR LOOP EARLIER THIS EVENING SHOWED A FINE LINE PUSHING INTO NE OHIO AND NW PA. THIS BOUNDARY REPRESENTS A SFC TROF SEPARATING DRY AIR OVR CENTRAL PA FROM EVEN DRIER AIR PUSHING IN FROM THE NORTH. LATEST SFC-8H LYR DWPTS FROM NAM AND RAP PICK UP THIS FEATURE WELL AND SUGGEST THE BNDRY AND DRIEST AIR NEVER REACH THE LAUREL HIGHLANDS. THEREFORE...EXPECT THE NW MTNS TO SEE THE COOLEST TEMPS RELATIVE TO NORMAL WITH MINS DROPPING INTO THE U30S IN THE NORMALLY COLDER VALLEYS. ONLY POSSIBLE WILD CARD WILL BE CIRRUS SPREADING IN AHEAD OF FAST-MOVING SHORTWAVE OVR THE GRT LKS. CURRENT THINKING IS THAT THESE HIGH CLOUDS WILL BE THIN ENOUGH TO NOT SIGNIFICANTLY DAMPEN RADIATIONAL COOLING. HAVE LOWERED OVERNIGHT TEMPS TO ARND 40F OVR THE NW MTNS...TO THE M50S FROM MDT SOUTH AND EAST. A NEARLY CALM WIND...AND WATER TEMPS NEARLY 30F WARMER THAN ANTICIPATED AIR TEMPS...SHOULD RESULT IN A NEAR CERTAINTY OF FOG LATE TONIGHT IN THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES...ESP NORTH OF I-80. PATCHY FOG ALSO LIKELY FURTHER EAST WITHIN THE RIDGE/VALLEY REGION FROM AOO TO UNV AND SEG...ESP NEAR ANY BODIES OF WATER. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... ANY PATCHY FOG WILL LIFT/DISSIPATE BETWEEN 13-15Z. THE FAIR/DRY WEATHER WILL PREVAIL TOMORROW WITH SFC HIGH PRESSURE IN CONTROL OF THE REGIONAL WEATHER PATTERN. HIGH QUALITY CANADIAN AIRMASS WILL FOSTER COMFORTABLE TEMPS AND HUMIDITY. A DECENT AMT OF SUNSHINE SHOULD EASILY ALLOW MIXING TO 850MB AND ENS MEAN 850 TEMPS ARND 10C SHOULD TRANSLATE TO MAX TEMPS IN THE 70S. AS THE SIGNIFICANT AREA OF COOL HIGH PRESSURE OVER PA SLIDES TO THE EAST LATE MONDAY INTO MONDAY NIGHT...A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 06-12Z TUE TIMEFRAME. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... WEAK TO MODERATE WSWRLY FLOW ALOFT AT THE START OF THE PERIOD WILL TURN MORE NWRLY AS HUDSON BAY UPPER LOW PROGRESSES INTO EASTERN CANADA BY THE END OF THE PERIOD. PLENTY OF WEAK SHORTWAVE TROFS WILL BE PRESENT TO BRING WEAK FRONTS THROUGH THE REGION DURING THE PERIOD. A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF 04/12Z OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 00-12Z TUE TIMEFRAME UPPER RIDGE OVER NUNAVUT/NW TERRITORIES WILL MAINTAIN MEAN TROUGHING OVER SERN CANADA...ANCHORED BY A CLOSED LOW TRACKING EWD ACRS MANITOBA/ONTARIO INTO QUEBEC BY THE END OF THE PERIOD. MODEL SPREAD IN THE TIMING OF THE LOW IS IMPACTING SFC/PCPN DETAILS DOWNSTREAM. SHORTWAVE ENERGY ROTATING AROUND THE BASE OF THE CLOSED LOW WILL PROPEL A SFC FRONT FROM THE NRN PLAINS SEWD THRU THE MIDWEST/OH VLY TUE-WED BEFORE SLOWING ITS PROGRESSION OVER THE APPLCHNS AND MID-ATLC STATES THU-FRI. WAVES OF LOW PRES RIDING ALONG THE FRONT WILL BE ACCOMPANIED BY RNFL OF VARYING INTENSITY WED-FRI...WITH SCT CONVECTION PRECEDING A WARM FRONT ON TUE. THE OVERALL PATTERN LOOKS PERIODICALLY WET AND UNSETTLED...WITH SEVERAL BOUTS OF SHOWERS/TSTMS TUE-FRI. SOME MODERATION IN DAILY TEMPS SHOULD OCCUR AHEAD OF THE FRONT. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... NOT MUCH CHANGE ON THE 03Z TAF PACKAGE. WINDS HOLDING UP FAIRLY GOOD IN SOME SPOTS...SUCH AS JST. EARLIER DISCUSSION BELOW. DID CUT DOWN ON FOG TONIGHT. SLIGHT NW WIND LIKELY IN MOST AREAS. AIRMASS ALSO QUITE DRY. MOST LIKELY SPOT TO SEE FOG WILL BE BFD. ALSO DEWPTS FCST TO DROP OFF...THUS LESS LIKELY FOR TEMPS TO REACH CROSS OVER VALUE. MONDAY LOOKS LIKE A NICE DAY...NOT A LOT OF WIND...AND VFR CONDITIONS. MAYBE A SHOWER OR THUNDERSTORM LATE MONDAY NIGHT INTO TUE. A HIGHER CHC FOR A SHOWER OR STORM ON WED...AS WARM FRONT MOVES ACROSS THE REGION. MAIN CHC FOR A SHOWER OR STORM WILL BE ON THU...MAINLY LATER IN THE DAY ACROSS THE NW. MORE WIDESPREAD ACTIVITY WILL BE POSSIBLE BY FRIDAY...AS A COLD FRONT MOVES ACROSS THE REGION. OVERALL A LOT OF VARIATION IN MODEL SOLUTIONS...GIVEN A COMPLEX PATTERN. JET STREAM STRONGER AND FURTHER SOUTH THAN WHAT ONE NORMALLY SEES IN EARLY AUG. OUTLOOK... TUE-WED...MAINLY VFR...BUT A CHC OF SHOWERS AND STORMS. THU-FRI...VFR BUT MVFR IN SHOWERS AND STORMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...CERU/STEINBUGL LONG TERM...GARTNER/STEINBUGL AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1045 PM EDT SUN AUG 4 2013 .SYNOPSIS... A BELT OF FAST WNW FLOW ALOFT WILL EXTEND FROM THE DAKOTAS TO THE MID-ATLANTIC COAST THROUGH THE MIDDLE OF THE WEEK...AS THE DEEP TROUGH OVER THE NORTHEAST SLIDES OFFSHORE AND PIVOTS AROUND A LARGE VORTEX MOVING SOUTHWEST FROM HUDSON BAY INTO SOUTH-CENTRAL CANADA. UPPER LEVEL HEIGHTS SHOULD RISE DURING THE SECOND HALF OF THE WEEK AS THE MID-LEVEL FLOW SHIFTS TO THE WEST-SOUTHWEST. AT THE SURFACE...HIGH PRESSURE OVER LK MICHIGAN THIS EVENING WILL MIGRATE OVER PENNSYLVANIA ON MONDAY BEFORE SLIDING OFF THE COAST MONDAY NIGHT. INCREASING MOISTURE IN ADVANCE OF A PLAINS/MIDWEST FRONTAL SYSTEM WILL BRING PERIODS RAIN FROM TUESDAY THROUGH THE END OF THE WEEK. BELOW NORMAL TEMPERATURES WILL MODERATE THROUGH THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... STAGE IS SET FOR A VERY COOL NIGHT /FOR EARLY AUGUST/ ACROSS CENTRAL PA...AS NEGATIVE PWAT AND 8H TEMPS ANOMALIES ON THE ORDER OF -2SD WILL ACCOMPANY SFC HIGH BUILDING OVR THE STATE. KCLE RADAR LOOP EARLIER THIS EVENING SHOWED A FINE LINE PUSHING INTO NE OHIO AND NW PA. THIS BOUNDARY REPRESENTS A SFC TROF SEPARATING DRY AIR OVR CENTRAL PA FROM EVEN DRIER AIR PUSHING IN FROM THE NORTH. LATEST SFC-8H LYR DWPTS FROM NAM AND RAP PICK UP THIS FEATURE WELL AND SUGGEST THE BNDRY AND DRIEST AIR NEVER REACH THE LAUREL HIGHLANDS. THEREFORE...EXPECT THE NW MTNS TO SEE THE COOLEST TEMPS RELATIVE TO NORMAL WITH MINS DROPPING INTO THE U30S IN THE NORMALLY COLDER VALLEYS. ONLY POSSIBLE WILD CARD WILL BE CIRRUS SPREADING IN AHEAD OF FAST-MOVING SHORTWAVE OVR THE GRT LKS. CURRENT THINKING IS THAT THESE HIGH CLOUDS WILL BE THIN ENOUGH TO NOT SIGNIFICANTLY DAMPEN RADIATIONAL COOLING. HAVE LOWERED OVERNIGHT TEMPS TO ARND 40F OVR THE NW MTNS...TO THE M50S FROM MDT SOUTH AND EAST. A NEARLY CALM WIND...AND WATER TEMPS NEARLY 30F WARMER THAN ANTICIPATED AIR TEMPS...SHOULD RESULT IN A NEAR CERTAINTY OF FOG LATE TONIGHT IN THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES...ESP NORTH OF I-80. PATCHY FOG ALSO LIKELY FURTHER EAST WITHIN THE RIDGE/VALLEY REGION FROM AOO TO UNV AND SEG...ESP NEAR ANY BODIES OF WATER. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... ANY PATCHY FOG WILL LIFT/DISSIPATE BETWEEN 13-15Z. THE FAIR/DRY WEATHER WILL PREVAIL TOMORROW WITH SFC HIGH PRESSURE IN CONTROL OF THE REGIONAL WEATHER PATTERN. HIGH QUALITY CANADIAN AIRMASS WILL FOSTER COMFORTABLE TEMPS AND HUMIDITY. A DECENT AMT OF SUNSHINE SHOULD EASILY ALLOW MIXING TO 850MB AND ENS MEAN 850 TEMPS ARND 10C SHOULD TRANSLATE TO MAX TEMPS IN THE 70S. AS THE SIGNIFICANT AREA OF COOL HIGH PRESSURE OVER PA SLIDES TO THE EAST LATE MONDAY INTO MONDAY NIGHT...A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 06-12Z TUE TIMEFRAME. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... WEAK TO MODERATE WSWRLY FLOW ALOFT AT THE START OF THE PERIOD WILL TURN MORE NWRLY AS HUDSON BAY UPPER LOW PROGRESSES INTO EASTERN CANADA BY THE END OF THE PERIOD. PLENTY OF WEAK SHORTWAVE TROFS WILL BE PRESENT TO BRING WEAK FRONTS THROUGH THE REGION DURING THE PERIOD. A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF 04/12Z OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 00-12Z TUE TIMEFRAME UPPER RIDGE OVER NUNAVUT/NW TERRITORIES WILL MAINTAIN MEAN TROUGHING OVER SERN CANADA...ANCHORED BY A CLOSED LOW TRACKING EWD ACRS MANITOBA/ONTARIO INTO QUEBEC BY THE END OF THE PERIOD. MODEL SPREAD IN THE TIMING OF THE LOW IS IMPACTING SFC/PCPN DETAILS DOWNSTREAM. SHORTWAVE ENERGY ROTATING AROUND THE BASE OF THE CLOSED LOW WILL PROPEL A SFC FRONT FROM THE NRN PLAINS SEWD THRU THE MIDWEST/OH VLY TUE-WED BEFORE SLOWING ITS PROGRESSION OVER THE APPLCHNS AND MID-ATLC STATES THU-FRI. WAVES OF LOW PRES RIDING ALONG THE FRONT WILL BE ACCOMPANIED BY RNFL OF VARYING INTENSITY WED-FRI...WITH SCT CONVECTION PRECEDING A WARM FRONT ON TUE. THE OVERALL PATTERN LOOKS PERIODICALLY WET AND UNSETTLED...WITH SEVERAL BOUTS OF SHOWERS/TSTMS TUE-FRI. SOME MODERATION IN DAILY TEMPS SHOULD OCCUR AHEAD OF THE FRONT. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... JUST A FEW SC AND CU LEFT. DID CUT DOWN ON FOG TONIGHT. SLIGHT NW WIND LIKELY IN MOST AREAS. AIRMASS ALSO QUITE DRY. MOST LIKELY SPOT TO SEE FOG WILL BE BFD. ALSO DEWPTS FCST TO DROP OFF...THUS LESS LIKELY FOR TEMPS TO REACH CROSS OVER VALUE. MONDAY LOOKS LIKE A NICE DAY...NOT A LOT OF WIND...AND VFR CONDITIONS. MAYBE A SHOWER OR THUNDERSTORM LATE MONDAY NIGHT INTO TUE. A HIGHER CHC FOR A SHOWER OR STORM ON WED...AS WARM FRONT MOVES ACROSS THE REGION. MAIN CHC FOR A SHOWER OR STORM WILL BE ON THU...MAINLY LATER IN THE DAY ACROSS THE NW. MORE WIDESPREAD ACTIVITY WILL BE POSSIBLE BY FRIDAY...AS A COLD FRONT MOVES ACROSS THE REGION. OVERALL A LOT OF VARIATION IN MODEL SOLUTIONS...GIVEN A COMPLEX PATTERN. JET STREAM STRONGER AND FURTHER SOUTH THAN WHAT ONE NORMALLY SEES IN EARLY AUG. OUTLOOK... TUE-WED...MAINLY VFR...BUT A CHC OF SHOWERS AND STORMS. THU-FRI...VFR BUT MVFR IN SHOWERS AND STORMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...CERU/STEINBUGL LONG TERM...GARTNER/STEINBUGL AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
810 PM EDT SUN AUG 4 2013 .SYNOPSIS... A BELT OF FAST WNW FLOW ALOFT WILL EXTEND FROM THE DAKOTAS TO THE MID-ATLANTIC COAST THROUGH THE MIDDLE OF THE WEEK...AS THE DEEP TROUGH OVER THE NORTHEAST SLIDES OFFSHORE AND PIVOTS AROUND A LARGE VORTEX MOVING SOUTHWEST FROM HUDSON BAY INTO SOUTH-CENTRAL CANADA. UPPER LEVEL HEIGHTS SHOULD RISE DURING THE SECOND HALF OF THE WEEK AS THE MID-LEVEL FLOW SHIFTS TO THE WEST-SOUTHWEST. AT THE SURFACE...HIGH PRESSURE OVER LK MICHIGAN THIS EVENING WILL MIGRATE OVER PENNSYLVANIA ON MONDAY BEFORE SLIDING OFF THE COAST MONDAY NIGHT. INCREASING MOISTURE IN ADVANCE OF A PLAINS/MIDWEST FRONTAL SYSTEM WILL BRING PERIODS RAIN FROM TUESDAY THROUGH THE END OF THE WEEK. BELOW NORMAL TEMPERATURES WILL MODERATE THROUGH THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... AS OF 00Z THE LAST OF THE -SHRA HAVE DIED OUT ACROSS NORTHEAST PA AND VIS LOOP SHOWING COLLAPSING CU ACROSS CENTRAL PA...THE RESULT OF LG SCALE SUBSIDENCE OVERSPREADING THE REGION IN WAKE OF DEPARTING SHORTWAVE. EXPECT CLEARING TREND TO CONTINUE THIS EVENING AS BLYR COOLS...WITH A MAINLY CLEAR SKY OVERNIGHT. STAGE IS SET FOR A VERY COOL NIGHT /FOR EARLY AUGUST/ ACROSS CENTRAL PA...AS NEGATIVE PWAT AND 8H TEMPS ANOMALIES ON THE ORDER OF -2SD WILL ACCOMPANY SFC HIGH BUILDING OVR THE STATE. KCLE RADAR LOOP SHOWING FINE LINE PUSHING INTO NE OHIO AND NW PA AT 00Z. THIS BOUNDARY REPRESENTS A SFC TROF SEPARATING DRY AIR OVR CENTRAL PA AND VERY DRY AIR TO THE NORTH. LATEST SFC-8H LYR DWPTS FROM RAP PICK UP THIS FEATURE WELL AND SUGGEST THE BNDRY AND DRIEST AIR NEVER REACH THE LAUREL HIGHLANDS. THEREFORE...EXPECT THE NW MTNS TO SEE THE COOLEST TEMPS RELATIVE TO NORMAL WITH MINS DROPPING INTO THE U30S IN THE NORMALLY COLDER VALLEYS. ONLY POSSIBLE WILD CARD WILL BE CIRRUS SPREADING IN AHEAD OF FAST-MOVING SHORTWAVE OVR THE GRT LKS. CURRENT THINKING IS THAT THESE HIGH CLOUDS WILL BE THIN ENOUGH TO NOT SIGNIFICANTLY DAMPEN RADIATIONAL COOLING. HAVE LOWERED OVERNIGHT TEMPS TO ARND 40F OVR THE NW MTNS...TO THE M50S FROM MDT SOUTH AND EAST. A NEARLY CALM WIND...AND WATER TEMPS NEARLY 30F WARMER THAN ANTICIPATED AIR TEMPS...SHOULD RESULT IN A NEAR CERTAINTY OF DENSE FOG LATE TONIGHT IN THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES...ESP NORTH OF I-80. PATCHY FOG ALSO LIKELY FURTHER EAST WITHIN THE RIDGE/VALLEY REGION FROM AOO TO UNV AND SEG...ESP NEAR ANY BODIES OF WATER. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... ANY PATCHY FOG WILL LIFT/DISSIPATE BETWEEN 13-15Z. THE FAIR/DRY WEATHER WILL PREVAIL TOMORROW WITH SFC HIGH PRESSURE IN CONTROL OF THE REGIONAL WEATHER PATTERN. HIGH QUALITY CANADIAN AIRMASS WILL FOSTER COMFORTABLE TEMPS AND HUMIDITY. A DECENT AMT OF SUNSHINE SHOULD EASILY ALLOW MIXING TO 850MB AND ENS MEAN 850 TEMPS ARND 10C SHOULD TRANSLATE TO MAX TEMPS IN THE 70S. AS THE SIGNIFICANT AREA OF COOL HIGH PRESSURE OVER PA SLIDES TO THE EAST LATE MONDAY INTO MONDAY NIGHT...A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 06-12Z TUE TIMEFRAME. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... WEAK TO MODERATE WSWRLY FLOW ALOFT AT THE START OF THE PERIOD WILL TURN MORE NWRLY AS HUDSON BAY UPPER LOW PROGRESSES INTO EASTERN CANADA BY THE END OF THE PERIOD. PLENTY OF WEAK SHORTWAVE TROFS WILL BE PRESENT TO BRING WEAK FRONTS THROUGH THE REGION DURING THE PERIOD. A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF 04/12Z OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 00-12Z TUE TIMEFRAME UPPER RIDGE OVER NUNAVUT/NW TERRITORIES WILL MAINTAIN MEAN TROUGHING OVER SERN CANADA...ANCHORED BY A CLOSED LOW TRACKING EWD ACRS MANITOBA/ONTARIO INTO QUEBEC BY THE END OF THE PERIOD. MODEL SPREAD IN THE TIMING OF THE LOW IS IMPACTING SFC/PCPN DETAILS DOWNSTREAM. SHORTWAVE ENERGY ROTATING AROUND THE BASE OF THE CLOSED LOW WILL PROPEL A SFC FRONT FROM THE NRN PLAINS SEWD THRU THE MIDWEST/OH VLY TUE-WED BEFORE SLOWING ITS PROGRESSION OVER THE APPLCHNS AND MID-ATLC STATES THU-FRI. WAVES OF LOW PRES RIDING ALONG THE FRONT WILL BE ACCOMPANIED BY RNFL OF VARYING INTENSITY WED-FRI...WITH SCT CONVECTION PRECEDING A WARM FRONT ON TUE. THE OVERALL PATTERN LOOKS PERIODICALLY WET AND UNSETTLED...WITH SEVERAL BOUTS OF SHOWERS/TSTMS TUE-FRI. SOME MODERATION IN DAILY TEMPS SHOULD OCCUR AHEAD OF THE FRONT. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... JUST A FEW SC AND CU LEFT. DID CUT DOWN ON FOG TONIGHT. SLIGHT NW WIND LIKELY IN MOST AREAS. AIRMASS ALSO QUITE DRY. MOST LIKELY SPOT TO SEE FOG WILL BE BFD. ALSO DEWPTS FCST TO DROP OFF...THUS LESS LIKELY FOR TEMPS TO REACH CROSS OVER VALUE. MONDAY LOOKS LIKE A NICE DAY...NOT A LOT OF WIND...AND VFR CONDITIONS. MAYBE A SHOWER OR THUNDERSTORM LATE MONDAY NIGHT INTO TUE. A HIGHER CHC FOR A SHOWER OR STORM ON WED...AS WARM FRONT MOVES ACROSS THE REGION. MAIN CHC FOR A SHOWER OR STORM WILL BE ON THU...MAINLY LATER IN THE DAY ACROSS THE NW. MORE WIDESPREAD ACTIVITY WILL BE POSSIBLE BY FRIDAY...AS A COLD FRONT MOVES ACROSS THE REGION. OVERALL A LOT OF VARIATION IN MODEL SOLUTIONS...GIVEN A COMPLEX PATTERN. JET STREAM STRONGER AND FURTHER SOUTH THAN WHAT ONE NORMALLY SEES IN EARLY AUG. OUTLOOK... TUE-WED...MAINLY VFR...BUT A CHC OF SHOWERS AND STORMS. THU-FRI...VFR BUT MVFR IN SHOWERS AND STORMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...CERU/STEINBUGL LONG TERM...GARTNER/STEINBUGL AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
600 AM EDT SAT AUG 3 2013 .SYNOPSIS... AN UNSEASONABLY AMPLIFIED AND PERSISTENT EARLY AUGUST WEATHER PATTERN WILL BE HIGHLIGHTED BY HIGHER LATITUDE BLOCKING OVER NORTHERN CANADA AND MEAN TROUGHING OVER EASTERN NORTH AMERICA. THIS WILL RESULT IN A PERIOD OF RELATIVELY COOL TEMPERATURES THROUGH EARLY NEXT WEEK. SHOWERS WILL ACCOMPANY A COLD FRONT MOVING THROUGH THE AREA TODAY...FOLLOWED BY DRY WEATHER FOR SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... A SHORTWAVE TROUGH IS FCST TO DIG SEWD ACROSS THE GREAT LAKES REGION INTO THE NORTHEAST THROUGH TONIGHT...SENDING ITS ASSOCD COLD FRONT INTO THE SRN MID-ATLANTIC STATES BY 12Z SUNDAY. THE COLD FRONT WILL SERVE AS A FOCUS FOR SHOWERS AND PERHAPS A FEW ISOLD TSTMS AS IT PUSHES SEWD THRU CNTRL PA TODAY. STG WSWLY H85 LLJ WILL FEED MSTR EWD FM THE OH VLY INTO THE BOUNDARY...WITH THE BEST MSTR FLUX OCCURRING EARLY THIS MORNING. MODEL QPFS FOR THE MOST PART ARE IN REASONABLE AGREEMENT WITH LGT AMTS GENERALLY AOB 0.25 INCH. OVERALL...THE BEST CHC FOR RAIN TODAY WILL BE OVER AREAS ALONG AND TO THE SOUTH OF I-80...WITH SHOWERS BCMG LESS NMRS/MORE SCT INTO THE AFTN HOURS. SPC HAS PLACED A SEE TEXT LABEL NEAR THE PA/MD LINE...INDICATING A LOW/LIMITED THREAT FOR SVR STORMS...WHICH IS DUE TO AN OVERALL LACK OF BUOYANCY. HOWEVER..ANY CLOUD BREAKS/INSOLATION OF 60F DEWPOINT AIRMASS COULD LEAD TO POCKETS OF GREATER INSTABILITY WITH QUASI-LINER STORM MOTIONS TAPPING STG WINDS ALOFT AND UNIDIRECTIONAL DEEP-LAYER FLOW - ORIENTED PARALLEL TO THE FRONTAL BOUNDARY. WILL SEE HOW FAR NORTH THEY DRAW THE 5PCT DMGG WIND PROB WITH THE 13Z UPDATE FOR HWO PURPOSES. THE FRONT MAY BRIEFLY STALL-OUT OR BECOME Q-STNRY INVOF THE MASON DIXON LINE EARLY TONIGHT...AS A WAVE SLIDES EWD ALONG THE BOUNDARY. THIS MAY PROLONG SHOWERS ACRS THE SRN TIER ZONES AND THEREFORE KEPT THE HIGHEST POPS ALONG/SOUTH OF THE TURNPIKE. DRIER AIR WILL BE OVERSPREADING THE AREA FROM NORTH TO SOUTH WITH PWS DROPPING BELOW NORMAL ACRS THE ENTIRE AREA BY 12Z SUNDAY. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SFC HIGH PRESSURE WILL MOVE FROM WI INTO WRN PA BY 12Z MON BEFORE SLIDING OFF THE MID-ATLC COAST BY TUES MORNG. COOL AND DRY CONDITIONS WILL PREVAIL THRU MUCH OF THE PERIOD...WITH JUST A SCHC OF AN ISOLD SHOWER SUN AFTN AS PLUME OF RELATIVELY STEEP MID-LVL LAPSE RATES ROTATES THRU N-CNTRL AND NERN PA. TEMPS WILL AVG BELOW NORMAL. SUN NGT/MON MORNG LOOKS RATHER CHILLY WITH SOME AREAS IN THE NRN MTNS POSSIBLY DROPPING INTO THE UPPER 30S. AS THE HIGH SLIDES TO THE EAST...WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY WITH GFS/EC SUGGESTING SHOWERS PSBL IN SWRN/SCNTRL PA BY 12Z TUE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... SLY LLVL FLOW SHOULD BRING GRADUALLY WARMER/MORE HUMID AIR BACK INTO CNTRL PA ON TUES...WITH SOME ISOLD/SCT AFTN CONVECTION PSBL. RETROGRADING VORTEX OVER HUDSON BAY/SRN CANADA SHOULD ALLOW THE FLOW ALOFT TO SHIFT MORE TO THE SW INTO THE MIDDLE TO LATER PART OF NEXT WEEK. 00Z MDL AND ENSEMBLE DATA SHOW A COLD FRONT PROGRESSING EWD FM THE NRN PLAINS/UPPER GRT LKS TWD THE NORTHEAST AND MID-ATLC STATES DURING THE SECOND HALF OF NEXT WEEK. THIS FRONT WILL BE ACCOMPANIED BY RNFL OF VARYING INTENSITY AS IT CROSSES THE REGION SOMETIME WED-THR. THE FRONT MAY STALL OR SLOW DOWN AS IT NEARS THE COAST...WHICH WOULD KEEP SHOWERS IN THE FCST OVR SERN PA INTO FRIDAY BEFORE THINGS CLR OUT BY THE WEEKEND. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/... ALTHOUGH RADAR SHOWS A WIDESPREAD AREA OF RAIN SHOWERS CROSSING THE REGION...LITTLE ACTIVITY REACHING THE SURFACE EXCEPT IN SOME ISOLATED HEAVIER SHOWERS NEAR KERI. CURRENT OBSERVATIONS ALONG WITH RAP SHORT TERM FORECASTS INDICATE CEILINGS SHOULD REMAIN VFR TO MVFR THROUGH THE FORECAST PERIOD. THE LATEST CALL TO THE KBFD ASOS INDICATED 1100 FT OVC. IF ANY AIRFIELD WILL FLIRT WITH DROPPING BELOW VFR CEILINGS...THIS WOULD BE IT. KEPT ALL SITES IN LINE WITH CURRENT CONDITIONS WITH THE ADDITION OF VCSH BASED ON RADAR COVERAGE. ANY SHOWERS THAT DO REACH THE GROUND WILL BE SLIDING SOUTH THROUGH THE MID MORNING HOURS. WITH ONLY A MARGINAL SLIVER OF CAPE ACCOMPANYING THE PRECIP...DO NOT EXPECT CONVECTION TO DEVELOP. BY MID AFTERNOON...PRECIP SHOULD EXIT THE AREA. OUTLOOK... SUN-WED...VFR. NO SIG WX. AM FOG POSSIBLE. PERHAPS A SHOWER LATE WED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...TYBURSKI
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
327 AM EDT SAT AUG 3 2013 .SYNOPSIS... AN UNSEASONABLY AMPLIFIED AND PERSISTENT LARGE SCALE WEATHER PATTERN WILL BE HIGHLIGHTED BY HIGHER LATITUDE BLOCKING OVER NORTHERN CANADA AND MEAN TROUGHING OVER EASTERN NORTH AMERICA. THIS WILL RESULT IN A PERIOD OF RELATIVELY COOL TEMPERATURES THROUGH EARLY NEXT WEEK. SHOWERS WILL ACCOMPANY A COLD FRONT MOVING THROUGH THE AREA TODAY...FOLLOWED BY DRY WEATHER FOR SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... A SHORTWAVE TROUGH IS FCST TO DIG SEWD ACROSS THE GREAT LAKES REGION INTO THE NORTHEAST THIS PERIOD...SENDING ITS ASSOCD COLD FRONT /TRAILING FROM THE ST. LAWRENCE VALLEY SWWD THRU THE LOWER GREAT LKS/ INTO THE MID-ATLANTIC STATES BY 12Z SUNDAY. THE COLD FRONT WILL SERVE AS A FOCUS FOR SHOWERS AND PERHAPS A FEW ISOLD TSTMS AS IT PUSHES SEWD THRU CNTRL PA TODAY. STG WSWLY H85 LLJ WILL FEED MSTR EWD FM THE OH VLY INTO THE BOUNDARY...WITH THE BEST MSTR FLUX OCCURRING EARLY THIS MORNING. MODEL QPFS FOR THE MOST PART ARE IN REASONABLE AGREEMENT WITH AMTS GENERALLY AOB 0.25 INCH. OVERALL...THE BEST CHC FOR RAIN TODAY WILL BE OVER AREAS ALONG AND TO THE SOUTH OF I-80. SPC HAS PLACED A SEE TEXT LABEL NEAR THE PA/MD LINE...INDICATING A LOW/LIMITED THREAT FOR SVR STORMS...WHICH IS DUE TO AN OVERALL LACK OF BUOYANCY. HOWEVER..ANY CLOUD BREAKS/INSOLATION OF 60F DEWPOINT AIRMASS COULD LEAD TO POCKETS OF GREATER INSTABILITY WITH QUASI-LINER STORM MOTIONS TAPPING STG WINDS ALOFT AND UNIDIRECTIONAL DEEP-LAYER FLOW - ORIENTED PARALLEL TO THE FRONTAL BOUNDARY. THE FRONT MAY BRIEFLY STALL-OUT OR BECOME Q-STNRY INVOF THE MASON DIXON LINE EARLY TONIGHT...AS A WAVE SLIDES EWD ALONG THE BOUNDARY. THIS MAY PROLONG SHOWERS ACRS THE SRN TIER ZONES AND THEREFORE KEPT THE HIGHEST POPS ALONG/SOUTH OF THE TURNPIKE. DRIER AIR WILL BE OVERSPREADING THE AREA FROM NORTH TO SOUTH WITH PWS DROPPING BELOW NORMAL ACRS THE ENTIRE AREA BY 12Z SUNDAY. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SFC HIGH PRESSURE WILL MOVE FROM WI INTO WRN PA BY 12Z MON BEFORE SLIDING OFF THE MID-ATLC COAST BY MON NGT. COOL AND DRY CONDITIONS WILL PREVAIL THRU MUCH OF THE PERIOD...WITH JUST A SCHC OF AN ISOLD SHOWER SUN AFTN AS PLUME OF RELATIVELY STEEP MID-LVL LAPSE RATES ROTATES THRU N-CNTRL AND NERN PA. SUNDAY NIGHT-MONDAY MORNING LOOKS RATHER CHILLY BY EARLY AUGUST STANDARDS...WITH WIDESPREAD READINGS IN THE 45-55F RANGE. SOME OF THE USUALLY COLDER AREAS IN THE NRN MTNS COULD DROP INTO THE UPPER 30S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... CONSENSUS AMONG MED RANGE GUIDANCE FOR ANOTHER STRETCH OF COOL/DRY WX INTO EARLY NEXT WEEK...AS COLD FRONT PRESSES SOUTH OF PA AND COOL...CANADIAN HIGH PRES BUILDS SE ACROSS THE AREA. 00Z GEFS 8H TEMPS REMAIN BLW NORMAL MON WHEN DAYTIME MAXES WILL LIKELY BE 5-10F BLW NORMAL. NEGATIVE PWAT AND 8H TEMPS ANOMALIES IN THE ENSEMBLE OUTPUT POINT TOWARD AN IDEAL SETUP FOR RADIATIONAL COOLING MONDAY AND TUESDAY NIGHTS...AS SFC HIGH DRIFTS OVR THE AREA. FOR MANY PARTS OF CENTRAL PA THESE COULD BE THE COOLEST NIGHTS OF THE SUMMER SEASON. NORTHERN MTNS WILL BE SOLIDLY IN THE 40S...WITH LOWER TO MID 50S ELSEWHERE. AXIS OF UPPER TROUGH SHIFTS FROM THE NORTHEAST CONUS TO THE MIDWEST BY THE MID/LATE NEXT WEEK...INDICATING SLIGHTLY WARMER...MORE HUMID AIR WILL MAKE A RETURN. CAN/T RULE OUT AN ISOLD SHRA/TSRA CREEPING INTO THE SC MTNS AS EARLY AS TUE AFTN - AS HINTED BY BOTH THE EC/GFS. HOWEVER...THE NEXT CHANCE FOR WIDESPREAD PRECIPITATION WILL LIKELY NOT COME UNTIL LATE WED WITH ARRIVAL OF A WARM FRONT OR AN EVEN BETTER CHANCE THURSDAY AS NEXT COLD FRONT SLOWS AS IT PUSHES THROUGH. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... ALTHOUGH RADAR SHOWS A WIDESPREAD AREA OF RAIN SHOWERS CROSSING THE REGION...LITTLE ACTIVITY REACHING THE SURFACE EXCEPT IN SOME ISOLATED HEAVIER SHOWERS NEAR KERI. CURRENT OBSERVATIONS ALONG WITH RAP SHORT TERM FORECASTS INDICATE CEILINGS SHOULD REMAIN VFR TO MVFR THROUGH THE FORECAST PERIOD. THE LATEST CALL TO THE KBFD ASOS INDICATED 1100 FT OVC. IF ANY AIRFIELD WILL FLIRT WITH DROPPING BELOW VFR CEILINGS...THIS WOULD BE IT. KEPT ALL SITES IN LINE WITH CURRENT CONDITIONS WITH THE ADDITION OF VCSH BASED ON RADAR COVERAGE. ANY SHOWERS THAT DO REACH THE GROUND WILL BE SLIDING SOUTH THROUGH THE MID MORNING HOURS. WITH ONLY A MARGINAL SLIVER OF CAPE ACCOMPANYING THE PRECIP...DO NOT EXPECT CONVECTION TO DEVELOP. BY MID AFTERNOON...PRECIP SHOULD EXIT THE AREA. OUTLOOK... SUN-WED...VFR. NO SIG WX. AM FOG POSSIBLE. PERHAPS A SHOWER LATE WED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...RXR AVIATION...MARTIN/TYBURSKI
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
144 AM EDT SAT AUG 3 2013 .SYNOPSIS... A DEVELOPING LARGE HIGH LATITUDE BLOCK OVER NORTHERN CANADA WILL FORCE SHORT-WAVE ENERGY INTO EASTERN NORTH AMERICA FOR MOST OF THE NEXT 7 DAYS OR MORE. THE RESULT WILL BE A PERIOD OF RELATIVELY COOL DRY WEATHER WITH A MID-TROPOSPHERIC TROUGH OVER OUR REGION. A WEAK SURGE OF MOISTURE AHEAD OF ONE WAVE IN THE FLOW WILL TRIGGER SHOWERS EARLY SATURDAY A SECOND POTENTIAL SURGE OF MOISTURE WITH ANOTHER WAVE COULD BRING ANOTHER CHANCE OF SHOWERS AFTER WEDNESDAY OR THURSDAY. && .NEAR TERM /UNTIL 9 AM THIS MORNING/... RADAR SHOWS SOME LIGHT SHOWERS MOVING ACROSS PORTIONS OF WARREN AND MCKEAN COUNTIES AND NOW INTO CLEARFIELD COUNTY. MOST OF THE LIGHT RAIN IS NOT LIKELY REACHING THE GROUND IN MANY PLACES. A MORE ORGANIZED BAND AREA OF RAIN IS OVER WESTERN PA AND HEADED RAPIDLY TO THE EAST-SOUTHEAST. THERE IS MORE RAIN TO THE WEST OVER OHIO AND WITH WESTERLY FLOW OVER A GENERAL E-W SAGGING BOUNDARY GOING TO BE A SLOW PUSH FOR THIS BOUNDARY TO WORK INTO SOUTHERN PA OVERNIGHT AND INTO SATURDAY. MOST SITES SHOW LIGHT RAIN BUT 1 OR 2 OBSERVATIONS UNDER AN ENHANCE ECHO SHOW 3 BALL RAIN. MODIFIED GRIDS TO REFLECT THE RAIN OVER WESTERN PA. NUDGED GRIDS TOWARD AM WITH HRRR AND BLEND PREVIOUS GUIDANCE. STILL TRIED TO KEEP QPF LOW AND POPS IN MOST LOCATIONS IN THE CHANCE CATEGORY AS THIS SHOULD NOT BE A SIGNIFICANT RAINFALL. HIGHEST POPS IN THE 40-54 PERCENT RANGE SORT OF ACROSS OUR CENTRAL AND WESTERN AREAS. LOW PROBABILITY OF MUCH OVER 0.05 TO 0.10 INCHES BY SUNRISE AND MOST GUIDANCE IMPLIES HIGHER POPS SLIDE TO SOUTHEAST TOWARD SUNRISE. && .SHORT TERM /9 AM THIS MORNING THROUGH 6 PM SUNDAY/... MODELS CONTINUE TO SHOW HIGHER POPS FARTHER SOUTH NEAR MASON-DIXON LINE AND LOWER POPS TO NORTH. SHOULD BE A LIGHT EVENT AS PW IS ON THE LOW SIDE. TRIED TO SHOW POP GRADIENT LOWER TO NORTH AND HIGHER TO SOUTH NEAR MD BORDER LATER IN THE DAY. MINOR ADJUSTMENTS TO TEMPERATURES. PREVIOUS FORECAST: THE 18Z GEFS SHOWS BEST CHANCE RAINFALL ABOUT 8-2 PM ALONG MASON- DIXON LINE DROPPING OFF FAST TO NORTH. HARD FOR MOST MODELS TO CRANK OUT MORE THAN A FEW HUNDREDTHS OF A QPF. SREF FROM 15Z WAS WETTER BUT IT TOO FOCUSED HIGHEST POPS NEAR MASON-DIXON LINE. NORTHERN AREAS SHOULD BE RAIN FREE AND EXPECT WIDELY SCATTERED SHOWERS AND THUNDER IN CENTRAL. SHOWERS IN SOUTHERN AREAS NEAR THE LOW-LEVEL BOUNDARY SHOULD MOSTLY BE LIGHT AND SHOULD CLEAR MOST OF THE AREA BY MID AFTERNOON. GOOD NEWS IS PW IS NEAR NORMAL AND DROPS IN THE LATE AFTERNOON...PRETTY DRY COLUMN OF AIR OVER PA SO NOT A LOT TO WORK WITH. JUST A NOTE THAT THE WINDS QUITE STRONG AND PARALLEL TO THE BOUNDARY IN SOUTHERN PA. IF WE GET ANY THUNDERSTORMS THEY HAVE SOME GOOD WINDS TO TAP. GOOD NEWS IS THE CAPE IS REALLY LOW SO LARGE UPDRAFTS ARE NOT LIKELY TO DEVELOP. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... CONSENSUS AMONG MED RANGE GUIDANCE FOR ANOTHER STRETCH OF COOL/DRY WX SUNDAY INTO EARLY NEXT WEEK...AS COLD FRONT PRESSES SOUTH OF PA AND COOL...CANADIAN HIGH PRES BUILDS SE ACROSS THE AREA. 00Z GEFS 8H TEMPS REMAIN BLW NORMAL SUN-MON WHEN DAYTIME MAXES WILL LIKELY BE 5-10F BLW NORMAL. NEGATIVE PWAT AND 8H TEMPS ANOMALIES IN THE ENSEMBLE OUTPUT POINT TOWARD AN IDEAL SETUP FOR RADIATIONAL COOLING MONDAY AND TUESDAY NIGHTS...AS SFC HIGH DRIFTS OVR THE AREA. FOR MANY PARTS OF CENTRAL PA THESE COULD BE THE COOLEST NIGHTS OF THE SUMMER SEASON. NORTHERN MTNS WILL BE SOLIDLY IN THE 40S...WITH LOWER TO MID 50S ELSEWHERE. AXIS OF UPPER TROUGH SHIFTS FROM THE NORTHEAST CONUS TO THE MIDWEST BY THE MID/LATE NEXT WEEK...INDICATING SLIGHTLY WARMER...MORE HUMID AIR WILL MAKE A RETURN. CAN/T RULE OUT AN ISOLD SHRA/TSRA CREEPING INTO THE SC MTNS AS EARLY AS TUE AFTN - AS HINTED BY BOTH THE EC/GFS. HOWEVER...THE NEXT CHANCE FOR WIDESPREAD PRECIPITATION WILL LIKELY NOT COME UNTIL LATE WED WITH ARRIVAL OF A WARM FRONT OR AN EVEN BETTER CHANCE THURSDAY AS NEXT COLD FRONT SLOWS AS IT PUSHES THROUGH. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... ALTHOUGH RADAR SHOWS A WIDESPREAD AREA OF RAIN SHOWERS CROSSING THE REGION...LITTLE ACTIVITY REACHING THE SURFACE EXCEPT IN SOME ISOLATED HEAVIER SHOWERS NEAR KERI. CURRENT OBSERVATIONS ALONG WITH RAP SHORT TERM FORECASTS INDICATE CEILINGS SHOULD REMAIN VFR TO MVFR THROUGH THE FORECAST PERIOD. THE LATEST CALL TO THE KBFD ASOS INDICATED 1100 FT OVC. IF ANY AIRFIELD WILL FLIRT WITH DROPPING BELOW VFR CEILINGS...THIS WOULD BE IT. KEPT ALL SITES IN LINE WITH CURRENT CONDITIONS WITH THE ADDITION OF VCSH BASED ON RADAR COVERAGE. ANY SHOWERS THAT DO REACH THE GROUND WILL BE SLIDING SOUTH THROUGH THE MID MORNING HOURS. WITH ONLY A MARGINAL SLIVER OF CAPE ACCOMPANYING THE PRECIP...DO NOT EXPECT CONVECTION TO DEVELOP. BY MID AFTERNOON...PRECIP SHOULD EXIT THE AREA. OUTLOOK... SUN-WED...VFR. NO SIG WX. AM FOG POSSIBLE. PERHAPS A SHOWER LATE WED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GRUMM NEAR TERM...GRUMM SHORT TERM...GRUMM/RXR LONG TERM...RXR AVIATION...MARTIN/TYBURSKI
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
800 PM CDT SUN AUG 4 2013 .UPDATE... NOT ANTICIPATING ANY MAJOR CHANGES TNT. DID LOWER POPS SOME FOR THE WESTERN CWA WHERE IT APPEARS ANY CONVECTION IS HAVING A HARD TIME GETTING ITS ACT TOGETHER OVER THE WESTERN HIGH PLAINS. FOR THE NORTHEAST CWA WILL MAINTAIN DECENT CHC POPS. NICE LOOKING S/W IN WV IMAGERY OVER WESTERN NORTH DAKOTA IS HELPING PROVIDE THE LIFT FOR SOME STORMS SOUTH OF BISMARCK. SOME OF THAT ACTIVITY MAY MAKE ITS WAY DOWN INTO NORTHERN SOUTH DAKOTA THIS EVENING. ONLY PROBLEM IS THAT ITS STILL FAIRLY STABLE OVER THE NORTHEAST PART OF THE CWA PER THE 00Z RAOB. MEANWHILE THE HRRR CONTINUES TO DEVELOP ELEVATED OVERNIGHT STUFF ON THE NOSE OF THE LLJ AHEAD OF THAT PREVIOUSLY MENTIONED S/W...SO WILL LEAVE POPS AS IS DESPITE SOME CONCERNS ABOUT TOO MUCH STABILITY OVER THE EASTERN CWA. TEMPS LOOK OKAY. && .PREVIOUS DISCUSSION... .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT A WEALTH OF CLOUDS COVER THE CWA THIS AFTERNOON...MUCH OF IT MVFR ACROSS CENTRAL SD. THE SUMMER SUN HAS NOT BURNED THIS OFF AND VIS SATELLITE INDICATES IT IS STILL STUBBORN TO LEAVE AND RATHER THICK. LOOKS LIKE SKIES WILL STAY MOSTLY CLOUDY THROUGH THE AFTERNOON. WITH THE ABUNDANCE OF CLOUDS...THE ATMOSPHERE HAS NOT BEEN ALLOWED TO DESTABILIZE. THE ONLY AREA THAT HAS RECEIVED A GOOD AMOUNT OF SUN TODAY IS FAR WESTERN SD. MESOANALYSIS SHOWS THIS AREA IS PUSHING 2000 J/KG MLCAPE WITH 50 KNOTS 0-6KM SHEAR. FARTHER EAST TOWARDS THE MISSOURI VALLEY...ONLY ABOUT 500 J/KG MLCAPE AND A LARGE CAP STILL IN PLACE. SPC SLIGHT RISK THREAT STILL HIGHLIGHTS WESTERN SD AND THIS LOOKS GOOD BASED ON CURRENT SITUATION. THE CWA HAS BEEN QUIET ALL DAY LONG AND HAD TO CUT POPS BACK TO SLIGHT CHANCE THEN EVENTUALLY TO NOTHING THROUGHOUT THE DAY. RATHER DIFFICULT PRECIP FORECAST TONIGHT AS WELL AND HI RES MODELS NOT OFFERING UP MUCH HELP. IT APPEARS THERE MAY BE TWO AREAS OF FOCUS...WITH THE POSSIBILITY OF A LARGE PORTION OF THE CWA FALLING IN BETWEEN THE TWO BEST AREAS OF PRECIP POTENTIAL. THE FIRST AREA IS THE AREA OF WESTERN SD. WHATEVER FIRES LATER THIS AFTERNOON AND EVENING COULD BECOME STRONG TO SEVERE AND EVENTUALLY MAKE ITS WAY INTO THE FAR WESTERN COUNTIES BY THIS EVENING. BUT ANYTHING THAT MOVES EAST WILL ENCOUNTER MUCH MORE STABLE AIR. THE NEXT AREA TO WATCH IS THE FAR NORTHEAST CWA LATER THIS EVENING AND OVERNIGHT. WATER VAPOR IMAGERY SHOWS TWO SEPARATE WAVES OF ENERGY ACROSS MONTANA AND FAR SOUTHERN CANADA. THESE WAVES WILL SLIDE EAST-SOUTHEAST INTO THE REGION OVERNIGHT AND MODELS ARE SHOWING SHOWERS AND STORMS ACROSS EASTERN ND...FAR NORTHEAST SD AND INTO MN THIS EVENING AND OVERNIGHT. MUCAPE INCREASES TO 1000-1500 J/KG WITH BULK SHEAR OF AROUND 50 KNOTS. THERE COULD BE A FEW STRONGER STORMS WITHIN THE WAA REGIME ACROSS THE FAR NORTHEAST CWA LATER TONIGHT. TRIED TO CONSTRUCT POP GRIDS WITH HIGHER CHANCES ACROSS THE FAR NORTHEAST AND FAR SOUTHWEST...BUT CONFIDENCE THIS GO AROUND IS RATHER LOW. AFTER QUIET CONDITIONS ON MONDAY...WILL THEN BE WATCHING THE COLD FRONTAL PASSAGE ON TUESDAY. FAIRLY POTENT FRONT MOVING THROUGH DURING THE DAY AND CHANCES FOR SHOWERS AND STORMS LOOK PRETTY GOOD. THERE COULD BE A FEW STRONGER STORMS ON TUESDAY WITH 1000-1500 J/KG GENERALLY SPEAKING AND 50+ KNOTS OF SHEAR. ALTHOUGH...STRONGEST INSTABILITY IS SOUTH OF THE REGION. .LONG TERM...WEDNESDAY THROUGH SUNDAY BELOW NORMAL TEMPERATURES WILL CONTINUE TO RULE THE LONG TERM PERIOD. A STRONG SOUTHERN CANADIAN COLD VORTEX WILL WOBBLE SLOWLY EAST THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. THIS WILL PUT US IN CONTINUED COOL NORTHWEST FLOW. THIS FLOW WILL BECOME MORE WEST NORTHWEST THROUGH THE WEEKEND AS AN UPPER LEVEL RIDGE AXIS PUSHES IN FROM THE WEST. THE MODELS SHOW SURFACE CANADIAN HIGH PRESSURE DOMINATING THROUGH MOST OF THE LONG TERM. A COLD FRONT COMING ACROSS THE CWA FOR WEDNESDAY NIGHT AND THURSDAY WILL BRING CHANCES OF SHOWERS AND THUNDERSTORMS TO THE ENTIRE CWA. OTHERWISE...THE SHOWER/STORM CHANCES WILL BE CONFINED TO ALONG AND WEST OF THE MISSOURI RIVER FOR MOST OF THE REST OF THE LONG TERM AS SHORT WAVES COME OVER THE WESTERN RIDGE. AREAS MAINLY EAST OF THE MISSOURI RIVER SHOULD REMAIN MORE ON THE STABLE AND DRIER SIDE. ALSO WITH THE SURFACE HIGH PRESSURE...DONT EXPECT MUCH FOR WIND THROUGH THE ENTIRE LONG TERM. HIGHS THROUGH THE ENTIRE LONG TERM SHOULD BE MOSTLY IN THE 70S TO THE LOWER 80S ACROSS THE CWA. && .AVIATION... 00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS A MIX OF MVFR AND MOSTLY VFR CIGS WILL CONTINUE THROUGH THE EVENING ACROSS THE REGION. MEANWHILE SOME SHOWERS MAY SKIRT THE KATY REGION EARLY THIS EVENING...AND THEN AGAIN LATER TNT AT KATY/KABR AS A SYSTEM MOVES ACROSS NORTH DAKOTA. HOWEVER CONFIDENCE IN COVERAGE OF THE ACTIVITY LATER TNT IS LOW THUS FOR NOW WILL LEAVE OUT OF THE TERMINAL FORECASTS UNTIL TRENDS BECOME CLEARER. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...TDK SHORT TERM...TMT LONG TERM...MOHR AVIATION...TDK WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1248 PM CDT SAT AUG 3 2013 .UPDATE... ISSUED AT 1008 AM CDT SAT AUG 3 2013 STRATIFORM AREA TO NORTH OF NEBRASKA CONVECTION AGAIN CAUSING ISSUES WITH THE ONGOING FORECAST. MADE AN EARLIER UPDATE FOR WIDESPREAD LIGHT PRECIP IN THE SOUTHWEST CWA EARLY THIS MORNING... AND NOW CONSIDERING MORE OF THE LONGER RANGE IMPACTS IN SKYCOVER AND TEMPS. WITH PARENT CONVECTION NOW UNDERGOING A WEAKENING CYCLE...WOULD EXPECT THAT STRATIFORM AREA WOULD ALSO START TO DIMINISH STARTING IN THE NEXT HOUR OR TWO...AND HAVE TRIED TO DRAW THIS INTO THE HOURLY GRIDS. ALSO COMPLICATING IS THE DRIER AIRMASS AT LOW LEVELS TO THE EAST...ALL OF WHICH WILL BE ERODING ADVANCING PRECIP. HRRR HAS THE GENERAL IDEA...BUT FAR TOO EXTENSIVE. SHOULD GET PRETTY RAGGED BY THE TIME IT STRETCHES INTO NORTHEAST NEBRASKA BY VERY LATE MORNING...AND MUCH MORE LIKELY TO NOT MAKE IT TO KSUX WITH ALL ELEMENTS WORKING AGAINST THE AGGRESSIVE EASTWARD PUSH. ALSO...NOT VERY ENTHUSIASTIC ABOUT MENTION OF THUNDER WITH ACTIVITY. MUCH MORE LIKELY TO GET AN ISOLATED STORM DEVELOPING AFTER INITIAL STRATIFORM AREA SLIDES PAST ON THE BACK SIDE ACROSS THE LOWER BRULE AREA...ABOUT THE ONLY LOCATION TO EXHIBIT ANY ELEVATED INSTABILITY. PUSHED BACK DIURNAL RISE QUITE A BIT UNDER THICK CLOUD SHIELD THIS MORNING...AND KNOCKED BACK HIGHS ALREADY A COUPLE DEGREES IN THE SOUTHWEST LOCATION...BUT SOMEWHAT CAUTIOUS TO DO MUCH MORE GIVEN LIKELIHOOD OF LATER DAY PARTIAL CLEARING. PLAN TO SLOW UP THE RISES A BIT MORE...AND SHAVE PERHAPS ANOTHER DEGREE OR TWO OFF ON DAYTIME EXPECTATIONS FOR MORE CLOUDY LOCATIONS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 351 AM CDT SAT AUG 3 2013 CONVECTION FIRING EARLY THIS MORNING ACROSS WESTERN SOUTH DAKOTA ON THE NOSE OF AN INCREASING LOW LEVEL JET. EXPECT THIS AREA OF STORMS TO EXPAND SOME THIS MORNING...WITH A SOUTHEAST STORM MOTION. ELEVATED INSTABILITY REALLY DROPS OFF AS YOU HEAD EAST TOWARDS OUR CWA. THUS EXPECT ANY STRONGER ACTIVITY TO STAY SOUTH AND WEST INTO NEBRASKA. HOWEVER COULD SEE SOME LIGHTER RAIN OR POSSIBLY A THUNDERSTORM ON THE NORTHERN EDGE OF THE COMPLEX MAKE IT INTO THE SOUTHWEST PORTION OF THE CWA...TOWARDS GREGORY AND CHARLES MIX COUNTIES...THIS MORNING. OTHERWISE EXPECTING PARTLY TO MOSTLY SUNNY SKIES OVER THE AREA...WITH INCREASING SUN THE FURTHER NORTHEAST YOU GET. THINK WE SEE ENOUGH SUN TO REACH NEAR FULL MIXING POTENTIAL TODAY...HOWEVER THAT WILL STILL LEAVE US SEVERAL DEGREES BELOW NORMAL..WITH MID AND UPPER 70S COMMON. TONIGHT WILL LIKELY START MOSTLY CLEAR...WITH INCREASING CLOUDS FROM WEST TO EAST. IT AGAIN APPEARS LIKELY THAT CONVECTION WILL GET GOING ON THE THE LOW LEVEL JET WEST OF OUR AREA DURING THE FIRST PART OF THE NIGHT. LOOKS LIKE A STRONGER WAVE ACCOMPANYING THIS CONVECTION...AND BETTER ANTECEDENT MOISTURE OVERHEAD. THUS LOOKS LIKE A BETTER CHANCE THAT THIS THUNDERSTORM ACTIVITY MAKES IT INTO OUR CWA. ALTHOUGH AGAIN ELEVATED INSTABILITY IS PRETTY MINIMAL...THUS WOULD NOT EXPECT TO SEE ANY SEVERE WEATHER. TIMING SEEMS TO PUT THE CONVECTION ENTERING OUR WESTERN CWA A FEW HOURS EITHER SIDE OF 12Z. LOWS WILL RANGE FROM THE MID 50S EAST WHERE CLOUDS WILL BE LAST TO ARRIVE...TO AROUND 60 WEST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 351 AM CDT SAT AUG 3 2013 FOR THE DAY ON SUNDAY...ANTICIPATE AFOREMENTIONED CONVECTION TO SPREAD INTO THE WESTERN PORTIONS OF THE CWA THROUGH THE EARLY PART OF THE DAY PER LOW LEVEL FORCING VIA THE 850 MB JET...WITH HIGHER POPS ACROSS OUR NORTHWEST CLOSER TO THE BETTER LIFT SUPPORTED BY MODEL DIV Q FIELDS. THINK THERE WILL BE A GENERALLY DOWNWARD TREND IN CONVECTION THROUGH THE DAY AS LOW LEVEL FORCING WEAKENS. ALTHOUGH 850 MB TEMPERATURES WARM A TAD ON SUNDAY...THINK THAT CLOUD COVER/ASSOCIATED SHOWERS WILL KEEP READINGS DOWN ACROSS THE NORTHERN TWO THIRDS OF THE CWA...WITH HIGHS TOPPING OUT IN THE LOWER TO MID 70S OVER THAT AREA...TO NEAR 80 THROUGH THE LOWER MISSOURI RIVER VALLEY. ON SUNDAY NIGHT THINK THE BETTER CHANCE OF CONVECTION WILL EXIST OVER OUR NORTHEASTERN AREAS AS A SECONDARY SHORTWAVE DROPS THROUGH NORTHEASTERN SOUTH DAKOTA INTO SOUTHERN MINNESOTA OVERNIGHT. IT WILL BE A LITTLE MILDER ON SUNDAY NIGHT IN THE RETURN SOUTHERLY FLOW ON THE BACKSIDE OF AN EXITING SURFACE RIDGE...WITH LOWS GENERALLY IN THE LOWER 60S. WITH SUBSIDENCE BEHIND THE EXITING WAVE...EXPECT A LESSER CHANCE OF CONVECTION DURING THE DAY ON MONDAY. TEMPERATURES WILL CLIMB A BIT IN CONTINUED WARMING THERMAL PROFILES AND MORE SUN...WITH HIGHS INTO THE UPPER 70S TO MID 80S. CONVECTION EXPECTED TO DEVELOP OVER WESTERN SOUTH DAKOTA ON MONDAY NIGHT COULD PUSH INTO OUR WESTERN AREAS LATE...THOUGH MODELS OF COURSE DIFFERING ON HOW THIS SCENARIO EVOLVES. AN EVEN MILDER NIGHT EXPECTED WITH LOWS IN THE LOWER TO MID 60S. FARTHER INTO THE EXTENDED...MODELS IN FAIRLY DECENT AGREEMENT ON BRINGING A COLD FRONT THROUGH THE REGION LATER ON TUESDAY...WITH ADDITIONAL CONVECTION POSSIBLE. DEPENDING ON TIMING...CONVECTIVE PARAMETERS WOULD SUGGEST THAT SEVERE STORMS WOULD BE POSSIBLE ON TUESDAY AFTERNOON AND EVENING. AFTER THAT...MODELS IN AGREEMENT ON OUR AREA BEING IN A NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE REMAINDER OF THE WEEK AS A BROAD UPPER LEVEL LOW SPINS OVER EASTERN CANADA/NORTHERN GREAT LAKES REGION. THIS WILL KEEP BELOW NORMAL TEMPERATURES LOCKED OVER OUR AREA...WITH HIGHS GENERALLY IN THE 70S AND LOWS IN THE 50S. WITH OBVIOUS MODEL DIFFERENCES THAT FAR OUT...STUCK WITH CONSENSUS IN TERMS OF PRECIPITATION THROUGH THE PERIOD...WITH ONLY LOW CHANCES FOR THE END OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1247 PM CDT SAT AUG 3 2013 VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THROUGH LATE NIGHT... BEFORE IMPACTS OF CONVECTION PROPAGATING FROM THE WEST AND NORTHWEST ARRIVE IN THE KHON VICINITY AFTER DAYBREAK. DID INCLUDE SOME THUNDER WITH PRECIPITATION CHANCES DURING THE MORNING... BUT MAY EVEN GET SOME PRECIPITATION LINGERING SOMEWHAT LONGER THAN THE SOMEWHAT RESTRICTED MENTION WINDOW. DID TOSS IN INITIAL INDICATOR INTO KFSD TAF AS WELL...WITH LOW LEVEL JET SHIFTING EASTWARD LATE IN THE PERIOD. A FEW PERIODS OF MVFR VISIBILITIES COULD ACCOMPANY THE SHOWERS/STORMS IN KHON. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...CHAPMAN SHORT TERM...CHENARD LONG TERM...JM AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1010 AM CDT SAT AUG 3 2013 .UPDATE... ISSUED AT 1008 AM CDT SAT AUG 3 2013 STRATIFORM AREA TO NORTH OF NEBRASKA CONVECTION AGAIN CAUSING ISSUES WITH THE ONGOING FORECAST. MADE AN EARLIER UPDATE FOR WIDESPREAD LIGHT PRECIP IN THE SOUTHWEST CWA EARLY THIS MORNING... AND NOW CONSIDERING MORE OF THE LONGER RANGE IMPACTS IN SKYCOVER AND TEMPS. WITH PARENT CONVECTION NOW UNDERGOING A WEAKENING CYCLE...WOULD EXPECT THAT STRATIFORM AREA WOULD ALSO START TO DIMINISH STARTING IN THE NEXT HOUR OR TWO...AND HAVE TRIED TO DRAW THIS INTO THE HOURLY GRIDS. ALSO COMPLICATING IS THE DRIER AIRMASS AT LOW LEVELS TO THE EAST...ALL OF WHICH WILL BE ERODING ADVANCING PRECIP. HRRR HAS THE GENERAL IDEA...BUT FAR TOO EXTENSIVE. SHOULD GET PRETTY RAGGED BY THE TIME IT STRETCHES INTO NORTHEAST NEBRASKA BY VERY LATE MORNING...AND MUCH MORE LIKELY TO NOT MAKE IT TO KSUX WITH ALL ELEMENTS WORKING AGAINST THE AGGRESSIVE EASTWARD PUSH. ALSO...NOT VERY ENTHUSIASTIC ABOUT MENTION OF THUNDER WITH ACTIVITY. MUCH MORE LIKELY TO GET AN ISOLATED STORM DEVELOPING AFTER INITIAL STRATIFORM AREA SLIDES PAST ON THE BACK SIDE ACROSS THE LOWER BRULE AREA...ABOUT THE ONLY LOCATION TO EXHIBIT ANY ELEVATED INSTABILITY. PUSHED BACK DIURNAL RISE QUITE A BIT UNDER THICK CLOUD SHIELD THIS MORNING...AND KNOCKED BACK HIGHS ALREADY A COUPLE DEGREES IN THE SOUTHWEST LOCATION...BUT SOMEWHAT CAUTIOUS TO DO MUCH MORE GIVEN LIKELIHOOD OF LATER DAY PARTIAL CLEARING. PLAN TO SLOW UP THE RISES A BIT MORE...AND SHAVE PERHAPS ANOTHER DEGREE OR TWO OFF ON DAYTIME EXPECTATIONS FOR MORE CLOUDY LOCATIONS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 351 AM CDT SAT AUG 3 2013 CONVECTION FIRING EARLY THIS MORNING ACROSS WESTERN SOUTH DAKOTA ON THE NOSE OF AN INCREASING LOW LEVEL JET. EXPECT THIS AREA OF STORMS TO EXPAND SOME THIS MORNING...WITH A SOUTHEAST STORM MOTION. ELEVATED INSTABILITY REALLY DROPS OFF AS YOU HEAD EAST TOWARDS OUR CWA. THUS EXPECT ANY STRONGER ACTIVITY TO STAY SOUTH AND WEST INTO NEBRASKA. HOWEVER COULD SEE SOME LIGHTER RAIN OR POSSIBLY A THUNDERSTORM ON THE NORTHERN EDGE OF THE COMPLEX MAKE IT INTO THE SOUTHWEST PORTION OF THE CWA...TOWARDS GREGORY AND CHARLES MIX COUNTIES...THIS MORNING. OTHERWISE EXPECTING PARTLY TO MOSTLY SUNNY SKIES OVER THE AREA...WITH INCREASING SUN THE FURTHER NORTHEAST YOU GET. THINK WE SEE ENOUGH SUN TO REACH NEAR FULL MIXING POTENTIAL TODAY...HOWEVER THAT WILL STILL LEAVE US SEVERAL DEGREES BELOW NORMAL..WITH MID AND UPPER 70S COMMON. TONIGHT WILL LIKELY START MOSTLY CLEAR...WITH INCREASING CLOUDS FROM WEST TO EAST. IT AGAIN APPEARS LIKELY THAT CONVECTION WILL GET GOING ON THE THE LOW LEVEL JET WEST OF OUR AREA DURING THE FIRST PART OF THE NIGHT. LOOKS LIKE A STRONGER WAVE ACCOMPANYING THIS CONVECTION...AND BETTER ANTECEDENT MOISTURE OVERHEAD. THUS LOOKS LIKE A BETTER CHANCE THAT THIS THUNDERSTORM ACTIVITY MAKES IT INTO OUR CWA. ALTHOUGH AGAIN ELEVATED INSTABILITY IS PRETTY MINIMAL...THUS WOULD NOT EXPECT TO SEE ANY SEVERE WEATHER. TIMING SEEMS TO PUT THE CONVECTION ENTERING OUR WESTERN CWA A FEW HOURS EITHER SIDE OF 12Z. LOWS WILL RANGE FROM THE MID 50S EAST WHERE CLOUDS WILL BE LAST TO ARRIVE...TO AROUND 60 WEST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 351 AM CDT SAT AUG 3 2013 FOR THE DAY ON SUNDAY...ANTICIPATE AFOREMENTIONED CONVECTION TO SPREAD INTO THE WESTERN PORTIONS OF THE CWA THROUGH THE EARLY PART OF THE DAY PER LOW LEVEL FORCING VIA THE 850 MB JET...WITH HIGHER POPS ACROSS OUR NORTHWEST CLOSER TO THE BETTER LIFT SUPPORTED BY MODEL DIV Q FIELDS. THINK THERE WILL BE A GENERALLY DOWNWARD TREND IN CONVECTION THROUGH THE DAY AS LOW LEVEL FORCING WEAKENS. ALTHOUGH 850 MB TEMPERATURES WARM A TAD ON SUNDAY...THINK THAT CLOUD COVER/ASSOCIATED SHOWERS WILL KEEP READINGS DOWN ACROSS THE NORTHERN TWO THIRDS OF THE CWA...WITH HIGHS TOPPING OUT IN THE LOWER TO MID 70S OVER THAT AREA...TO NEAR 80 THROUGH THE LOWER MISSOURI RIVER VALLEY. ON SUNDAY NIGHT THINK THE BETTER CHANCE OF CONVECTION WILL EXIST OVER OUR NORTHEASTERN AREAS AS A SECONDARY SHORTWAVE DROPS THROUGH NORTHEASTERN SOUTH DAKOTA INTO SOUTHERN MINNESOTA OVERNIGHT. IT WILL BE A LITTLE MILDER ON SUNDAY NIGHT IN THE RETURN SOUTHERLY FLOW ON THE BACKSIDE OF AN EXITING SURFACE RIDGE...WITH LOWS GENERALLY IN THE LOWER 60S. WITH SUBSIDENCE BEHIND THE EXITING WAVE...EXPECT A LESSER CHANCE OF CONVECTION DURING THE DAY ON MONDAY. TEMPERATURES WILL CLIMB A BIT IN CONTINUED WARMING THERMAL PROFILES AND MORE SUN...WITH HIGHS INTO THE UPPER 70S TO MID 80S. CONVECTION EXPECTED TO DEVELOP OVER WESTERN SOUTH DAKOTA ON MONDAY NIGHT COULD PUSH INTO OUR WESTERN AREAS LATE...THOUGH MODELS OF COURSE DIFFERING ON HOW THIS SCENARIO EVOLVES. AN EVEN MILDER NIGHT EXPECTED WITH LOWS IN THE LOWER TO MID 60S. FARTHER INTO THE EXTENDED...MODELS IN FAIRLY DECENT AGREEMENT ON BRINGING A COLD FRONT THROUGH THE REGION LATER ON TUESDAY...WITH ADDITIONAL CONVECTION POSSIBLE. DEPENDING ON TIMING...CONVECTIVE PARAMETERS WOULD SUGGEST THAT SEVERE STORMS WOULD BE POSSIBLE ON TUESDAY AFTERNOON AND EVENING. AFTER THAT...MODELS IN AGREEMENT ON OUR AREA BEING IN A NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE REMAINDER OF THE WEEK AS A BROAD UPPER LEVEL LOW SPINS OVER EASTERN CANADA/NORTHERN GREAT LAKES REGION. THIS WILL KEEP BELOW NORMAL TEMPERATURES LOCKED OVER OUR AREA...WITH HIGHS GENERALLY IN THE 70S AND LOWS IN THE 50S. WITH OBVIOUS MODEL DIFFERENCES THAT FAR OUT...STUCK WITH CONSENSUS IN TERMS OF PRECIPITATION THROUGH THE PERIOD...WITH ONLY LOW CHANCES FOR THE END OF NEXT WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 617 AM CDT SAT AUG 3 2013 SOME PATCHY MORNING FOG WILL QUICKLY BURN OFF WITH SUNRISE. A FEW SHOWERS AND MAYBE A THUNDERSTORM WILL CLIP SOUTH CENTRAL SOUTH DAKOTA THIS MORNING...BUT ALL TAF SITES SHOULD REMAIN IN THE CLEAR. VFR CONDITIONS WILL THUS DOMINATE THROUGH THE DAY INTO THE FIRST PART OF TONIGHT. ANOTHER AREA OF CONVECTION MAY APPROACH HURON FROM THE WEST TOWARDS 12Z. DID ADD IN A TEMPO SHOWER GROUP. INSTABILITY IS LOW BUT COULD VERY WELL BE THUNDER WITH ANYTHING THAT MOVES IN...BUT HELD OFF ON MENTIONING UNTIL CONFIDENCE OF COVERAGE AND TIMING INCREASES. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...CHAPMAN SHORT TERM...CHENARD LONG TERM...JM AVIATION...CHENARD
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AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
142 PM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE AREA LATE TODAY INTO TONIGHT...PRECEDED AND ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. HIGH PRESSURE FOLLOWING THE FRONT WILL BRING DRIER AND COOLER AIR BACK INTO THE REGION SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1225 PM SATURDAY... MADE A QUICK ADJUSTMENT IN POPS FOR DEVELOPMENT OF CONVECTION THIS AFTERNOON AHEAD OF SHORTWAVE IN MOIST UNSTABLE AIR. ALSO MODIFIED TEMPERATURES AND DEW POINTS ACCORDING TO LATEST OBS AND MODEL TREND. DEW POINTS TEMPERATURES HAVE CLIMB TO AROUND 70 DEGREES ACROSS SOUTHERN PORTIONS OF CWA THIS AFTERNOON. THE COLD FRONT WILL DROP SOUTHEAST ACROSS THE REGION INTO TONIGHT. MORE CHANGES LATER THIS AFTERNOON. AS OF 950 AM EDT SATURDAY... KFCX 88D LOOP SHOWED SCATTERED SHOWERS TRAVELING EAST ACROSS CWA THIS MORNING ASSOCIATED WITH ISENTROPIC LIFT. EXPANDED THE LIGHT POPS TO THE EAST THIS MORNING...AS THEY BATTLE THE DOWNSLOPE FLOW. RNK WRF ARW SHOWED SHOWERS WEAKENING WITH PROGRESSION EASTWARD. THIS MORNING 8AM/12Z RNK SOUNDING INDICATED THAT PWATS HAVE INCREASED TO 1.20 INCH WITH A WEST FLOW. SHORTWAVE TROF WILL DROP SOUTHEAST TODAY INTO TONIGHT. A COOL FRONT WILL MOVE INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. A COUPLE OF WEAK BOUNDARIES AHEAD OF THE FRONT MAY COMBINE WITH LIMITED INSTABILITY TO CREATE WIDELY SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING HELP BY CONFLUENCE ZONE. NAM AND WRF INDICATED THAT BEST INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VIRGINIA INTO NORTH CENTRAL NORTH CAROLINA WHERE MUCH DEEPER LOW LEVEL MOISTURE RESIDES IN VICINITY OF OLD FRONT. IF CLOUD COVER THINS ENOUGH...SCATTERED SHOWERS AND THUNDERSTORMS COULD DEVELOP BY LATE AFTERNOON IN SOUTHEASTERN PART OF FORECAST AREA. A STRONGER THUNDERSTORM COULD CONTAIN GUSTY WINDS AND HEAVY DOWNPOURS. SHOWERS AND THUNDERSTORMS THIS EVENING INTO TONIGHT WILL DIMINISH WITH THE LOSS OF SOLAR HEATING AS SHORTWAVE ENERGY REMAINS WELL NORTH OF US. MADE SOME MINOR ADJUSTMENTS TO POPS...TEMPERATURES AND CLOUD COVER IN ISC GRIDS. AS OF 355 AM EDT SATURDAY... SCATTERED SHOWERS CURRENTLY MOVING EAST OUT OF EASTERN KY AND WV ON NOSE OF ISENTROPIC LIFT ZONE MAXIMIZED IN 850-700 MILLIBAR LAYER...AND WILL LIKELY CONTINUE EAST INTO NORTHWESTERN PORTION OF THE BLACKSBURG FORECAST AREA THROUGH THE DAYBREAK HOURS BEFORE DISSIPATING EAST OF THE BLUE RIDGE BY MID MORNING AS AREA ENCOUNTERS INCREASINGLY DOWNSLOPE FLOW. OTHERWISE...EXPECT TO SEE ANY EARLY MORNING FOG IN MOUNTAIN VALLEYS...AND ACROSS SOUTHSIDE VA INTO NORTH CENTRAL NC IN VICINITY OF OLD FRONTAL BOUNDARY RAPIDLY DISSIPATE WITH ONSET OF DAYTIME HEATING. TRICKY FORECAST FOR REST OF TODAY AS A COMBINATION OF WEATHER FEATURES COMPETE FOR ATTENTION. WIDESPREAD AREA OF SHOWERS CURRENTLY OVER OH VALLEY ASSOCIATED WITH FIRST IN SERIES OF SHORT WAVE TROFS THAT WILL PROGRESSIVELY CARVE OUT UPPER TROF OVER THE NORTHEASTERN PORTION OF THE NATION THIS WEEKEND...DRIVING COOL FRONT INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. LOCAL WRF AND HRRR MODELS INDICATING THAT PRECEDING AREA OF SHOWERS MAY HELP GENERATE AND PUSH OUTFLOW BOUNDARY SOUTHEAST OUT AHEAD OF THE FRONT INTO NORTHERN THIRD OF THE BLACKSBURG FORECAST AREA THIS AFTERNOON. DESPITE RATHER LACKLUSTER MID LEVEL INSTABILITY...AND POTENTIAL OF AT LEAST SOME OFFSET OF INSOLATIVE POTENTIAL DUE TO LINGERING MID AND HIGH LEVEL CLOUDS...WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED TO DEVELOP BY/DURING THE EARLY TO MID AFTERNOON IN ASSOCIATED CONFLUENCE ZONE... ESPECIALLY NORTH OF HIGHWAY 460...AND ACROSS WESTERN FLANKS OF THE APPALACHIANS AS WESTERLY UPSLOPING WINDS PROVIDE SOME NEEDED UPWARD ASSIST. MUCH BETTER INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VA INTO NORTH CENTRAL NC WHERE MUCH DEEPER LOW LEVEL/TROPICAL MOISTURE RESIDES IN VICINITY OF OLD FRONT. SHORT RANGE AND MESOSCALE MODELS HIGHLIGHT THIS AREA FOR ADDITIONAL SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ALTHOUGH ANY NORTHWARD PUSH OF THIS AIRMASS INTO VA APPEARS UNLIKELY CONSIDERING SLOW VEERING OF WINDS AS ZONAL FLOW INCREASES OVER AREA. IN LIGHT OF THE ABOVE...BEST THREAT FOR WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS TODAY WILL BE ACROSS THE NORTH...NORTHWEST...AND SOUTHEAST PORTION OF THE BLACKSBURG FORECAST AREA...WITH RELATIVE MINIMUM (MORE ISOLATED) THREAT FROM THE FOOTHILLS OF NORTHWEST NC NORTHEAST TOWARD FARMVILLE VA. SEVERE WEATHER THREAT AT THE PRESENT TIME APPEARS TO BE REMOTE. LOSS OF DAYTIME HEATING AND LITTLE TO NO DYNAMIC SUPPORT AS SHORT WAVE ENERGY REMAINS WELL NORTH OF THE BLACKSBURG AREA SHOULD SUPPORT DEMISE OF LINGERING SHOWER/THUNDERSTORM ACTIVITY IN MOST AREAS BEFORE MIDNIGHT TONIGHT...BUT WITH A LOW THREAT OF SOME STRAY SHOWERS REMAINING INTO THE EARLY MORNING HOURS ACROSS THE SOUTHWESTERN MOUNTAINS WHERE A BIT DEEPER MOISTURE PROFILE WILL RESIDE AS COLDER AIR FOLDS INTO AREA FROM THE NORTH. MOS GUIDANCE GENERALLY ACCEPTED FOR THE NEAR TERM PERIOD...WITH HIGHS TODAY IN THE 70S ACROSS THE HIGHER TERRAIN TO 80S ELSEWHERE...WITH OVERNIGHT LOWS MAINLY IN THE 60S EXCLUDING SOME MID TO UPPER 50S IN SOME OF THE DEEPER MOUNTAIN VALLEYS. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 430 AM EDT SATURDAY... A BRIEF AMPLIFICATION OF THE NW FLOW ALOFT WILL ALLOW A FAIRLY SUBSTANTIAL AREA OF COOL...DRY HIGH PRESSURE TO SPREAD SE ACROSS THE REGION BEHIND A COLD FRONT WHICH WILL PUSH INTO SOUTH CAROLINA BEFORE STALLING MONDAY. THIS WILL PROVIDE THE FORECAST AREA WITH A RESPITE FROM THE INCESSANT SHRA/TSRA ACTIVITY OF RECENT DAYS AND ALLOW A QUITE DRY AIR MASS TO SPREAD THROUGH THE AREA BY EARLY MON. ANY REMNANT -SHRA AROUND DAYBREAK SUN...SHOULD DISSIPATE QUICKLY AND SKIES SHOULD CLEAR EAST OF THE ALLEGHANYS. CANNOT RULE OUT LINGERING UPSLOPE SC ACROSS SE WV...BUT OVERALL EVEN THOSE AREAS SHOULD CLEAR OUT BY EVENING. TEMPS SUN SHOULD BE BELOW NORMAL WEST OF THE ALLEGHANYS...BUT NEAR NORMAL ACROSS THE PIEDMONT FROM STRONG INSOLATION AND DOWNSLOPE NW FLOW. MON MORNING SHOULD BE THE COOLEST MORNING OF THE NEXT SEVEN DAYS AND RIVAL THE RECENT PAST COUPLE OF COOL SPELLS WHERE MIN TEMPS DIPPED INTO THE UPPER 40S IN DEEPER MOUNTAIN VALLEYS WITH WIDESPREAD 50S WEST OF THE BLUE RIDGE...LOWER 60S ACROSS THE PIEDMONT. FOR TUE...THE FIRST IN A LONG SERIES OF NW FLOW DISTURBANCES TRACKS ACROSS THE REGION AS A PRONOUNCED BAROCLINIC ZONE BEGINS TO SET UP ACROSS THE REGION FROM NW-SE FROM THE OHIO VALLEY TOWARD THE MID-ATLANTIC...BEGINNING WHAT SHOULD BE A 3-5 DAY PERIOD OF QUITE ACTIVE CONVECTIVE WEATHER. FOR TUE...SFC MOISTURE WILL JUST BE RECOVERING...SO NOT EXPECTING AN OVERLY ACTIVE CONVECTIVE DAY JUST YET. THE MON SFC HIGH WILL MOVE TO A POSITION OFF THE MID- ATLANTIC COAST AND ALLOW A WEAK WEDGE SITUATION TO EVOLVE EAST OF THE BLUE RIDGE. FOR NOW...HAVE ADVERTISED LOW CHC POPS MOST AREAS...BUT THE BEST THREAT FOR PCPN APPEARS TO BE EAST OF OR NEAR THE ALLEGHANYS AT THIS TIME WHERE LOW-LEVEL MOISTURE CONVERGENCE AND SFC TD IS MAXIMIZED AND DIFFERENTIAL HEATING MAY HELP SPARK INITIAL CONVECTION DURING THE AFTERNOON. MAX/MIN TEMPS WILL BEGIN TO RECOVER FROM THE MON COOL SPELL AND SHOULD BE CLOSER TO NORMAL...EXCEPT STILL SLIGHTLY BELOW NORMAL IN THE FAR N-NW PART OF THE CWA. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 445 AM EDT SATURDAY... AS NOTED THE PAST SEVERAL DAYS...THIS PERIOD LOOKS TO BE QUITE ACTIVE WITH REGARD TO CONVECTION. THE FLOW WILL TREND TOWARD AN INCREASINGLY ZONAL FLOW WITH A SERIES OF EMBEDDED DISTURBANCES ALOFT. A WEAK COLD FRONT WILL BEGIN TO ENTER THE NW PART OF THE CWA BY THU...THEN ATTEMPT TO PUSH SLOWLY SOUTHEASTWARD THU-FRI. HOW FAR S-SE THE FRONT MOVES BEFORE STALLING IS HIGHLY QUESTIONABLE GIVEN THE INCREASING ZONAL FLOW IN PLACE AND A SUBTROPICAL RIDGE BUILDING ACROSS THE SE STATES. BOTH THE GFS AND ECMWF TRY TO PUSH THE FRONT COMPLETELY SOUTH OF OUR CWA BY SATURDAY AS IT STRENGTHENS THE NW FLOW JUST ENOUGH TO DO SO...BUT AS NOTED...THAT IS SOMEWHAT DOUBTFUL. AT ANY RATE...WED-THU LOOK QUITE ACTIVE AND PROBLEMATIC...ESPECIALLY IN TERMS OF FLASH FLOOD POTENTIAL. PWATS REACH OR EXCEED 2.0 INCHES ACROSS MUCH OF THE CWA WED- THU AFTERNOON. THIS COMBINED WITH PERIODIC AMPLE UPPER SUPPORT FROM EMBEDDED SHORT WAVES AND THE VERY WET ANTECEDENT CONDITIONS WILL HAVE TO BE WATCHED VERY CAREFULLY. WITH A NEARLY STALLED OR QUASI- STATIONARY FRONTAL BOUNDARY DRAPED ACROSS THE REGION AND FAVORABLE SUPPORT...TRAINING OF SHRA/TSRA ACTIVITY APPEARS LIKELY. FURTHERMORE...INSTABILITY LOOKS QUITE HEALTHY WITH CAPES REACHING 2000 J/KG OR GREATER WED AND THU AFTERNOON ACROSS MUCH OF THE CWA. THUS...A FEW STRONG TO SEVERE THUNDERSTORMS ALSO APPEAR LIKELY. HAVE INTRODUCED THE MENTION OF HEAVY RAIN TO THE ZFP FOR THESE PERIODS AND WILL ALSO CONTINUE TO INCLUDE THE THREAT OF HEAVY RAIN AND ISOLATED SEVERE IN THE HWO. HUMIDITY LEVELS WILL BE QUITE HIGH THROUGH THE EXTENDED PERIODS...SO THERE WILL BE LITTLE COOLING AT NIGHT. BY THE SAME TOKEN...MAX TEMPS SHOULD REMAIN NEAR NORMAL...PERHAPS SLIGHTLY BELOW IN AREAS THAT HAVE ENOUGH CLOUD COVER/PCPN TO LIMIT HEATING. NONETHELESS...IT WILL BE QUITE MUGGY AND MUCH MORE UNCOMFORTABLE THAN THE BEGINNING OF THE WEEK. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 130 PM EDT SATURDAY... A COLD FRONT WILL DROP SOUTHEAST THROUGH THE AREA TONIGHT INTO SUNDAY. SCATTERED MVFR SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG AND AHEAD OF THE FRONT THIS AFTERNOON INTO TONIGHT. THE FOCUS FOR CONVECTION FOR THE NEXT COUPLE OF HOURS WILL BE ALONG A MOISTURE CONVERGENCE ZONE ACROSS SOUTHEAST PORTIONS OF CWA. EXPECT A BAND OF CONVECTION TO REDEVELOP ACROSS THE NORTH AFTER 19Z AND TRAVEL SOUTHEAST THIS EVENING INTO TONIGHT. OVERNIGHT...A FEW -SHRA MAY REDEVELOP ACROSS WV AND MOVE TOWARD THE NEW RIVER/ROANOKE VALLEY BEFORE DISSIPATING. MOSTLY VFR CIGS EXPECTED WITH THIS ACTIVITY AS WELL. THE EXCEPTION TO CIGS OVERNIGHT WILL BE IN UPSLOPE AREAS OF SE WV...WHERE MVFR CIGS/MVFR VSBYS COULD DEVELOP FROM BLF- LWB...ESPECIALLY BLF AS TYPICAL WITH THIS SCENARIO. WINDS WSW 5-10KTS THIS AFTERNOON...BECOMING WNW-NW BEHIND THE FRONT OVERNIGHT AT SPEEDS OF 5-7KTS. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH TAF VALID PERIOD. HIGH CONFIDENCE IN WIND SPD/DIR THROUGH TAF VALID PERIOD. MEDIUM CONFIDENCE IN TSRA POTENTIAL THIS AFTERNOON/TONIGHT. EXTENDED AVIATION DISCUSSION... VFR CONDITIONS EXPECTED SUN-MON...OUTSIDE SOME EARLY MORNING MVFR CIGS SE WV SITES. SPOTTY AFTERNOON CONVECTION POSSIBLE TUE AFTERNOON...MAINLY LYH/DAN/ROA. WEDNESDAY THROUGH FRIDAY BRINGS WIDESPREAD CONVECTION BACK TO THE CWA...WITH ATTENDANT LOWER CIGS/VSBYS AS TROPICAL MOISTURE RETURNS TO THE AREA AND A QUASI- STATIONARY FRONTAL BOUNDARY DRIFTS SLOWLY SOUTHWARD THROUGH THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WERT NEAR TERM...KK/WERT SHORT TERM...RAB LONG TERM...RAB/WP AVIATION...KK/RAB
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1231 PM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE AREA LATE TODAY INTO TONIGHT...PRECEDED AND ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. HIGH PRESSURE FOLLOWING THE FRONT WILL BRING DRIER AND COOLER AIR BACK INTO THE REGION SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1225 PM SATURDAY... MADE A QUICK ADJUSTMENT IN POPS FOR DEVELOPMENT OF CONVECTION THIS AFTERNOON AHEAD OF SHORTWAVE IN MOIST UNSTABLE AIR. ALSO MODIFIED TEMPERATURES AND DEW POINTS ACCORDING TO LATEST OBS AND MODEL TREND. DEW POINTS TEMPERATURES HAVE CLIMB TO AROUND 70 DEGREES ACROSS SOUTHERN PORTIONS OF CWA THIS AFTERNOON. THE COLD FRONT WILL DROP SOUTHEAST ACROSS THE REGION INTO TONIGHT. MORE CHANGES LATER THIS AFTERNOON. AS OF 950 AM EDT SATURDAY... KFCX 88D LOOP SHOWED SCATTERED SHOWERS TRAVELING EAST ACROSS CWA THIS MORNING ASSOCIATED WITH ISENTROPIC LIFT. EXPANDED THE LIGHT POPS TO THE EAST THIS MORNING...AS THEY BATTLE THE DOWNSLOPE FLOW. RNK WRF ARW SHOWED SHOWERS WEAKENING WITH PROGRESSION EASTWARD. THIS MORNING 8AM/12Z RNK SOUNDING INDICATED THAT PWATS HAVE INCREASED TO 1.20 INCH WITH A WEST FLOW. SHORTWAVE TROF WILL DROP SOUTHEAST TODAY INTO TONIGHT. A COOL FRONT WILL MOVE INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. A COUPLE OF WEAK BOUNDARIES AHEAD OF THE FRONT MAY COMBINE WITH LIMITED INSTABILITY TO CREATE WIDELY SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING HELP BY CONFLUENCE ZONE. NAM AND WRF INDICATED THAT BEST INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VIRGINIA INTO NORTH CENTRAL NORTH CAROLINA WHERE MUCH DEEPER LOW LEVEL MOISTURE RESIDES IN VICINITY OF OLD FRONT. IF CLOUD COVER THINS ENOUGH...SCATTERED SHOWERS AND THUNDERSTORMS COULD DEVELOP BY LATE AFTERNOON IN SOUTHEASTERN PART OF FORECAST AREA. A STRONGER THUNDERSTORM COULD CONTAIN GUSTY WINDS AND HEAVY DOWNPOURS. SHOWERS AND THUNDERSTORMS THIS EVENING INTO TONIGHT WILL DIMINISH WITH THE LOSS OF SOLAR HEATING AS SHORTWAVE ENERGY REMAINS WELL NORTH OF US. MADE SOME MINOR ADJUSTMENTS TO POPS...TEMPERATURES AND CLOUD COVER IN ISC GRIDS. AS OF 355 AM EDT SATURDAY... SCATTERED SHOWERS CURRENTLY MOVING EAST OUT OF EASTERN KY AND WV ON NOSE OF ISENTROPIC LIFT ZONE MAXIMIZED IN 850-700 MILLIBAR LAYER...AND WILL LIKELY CONTINUE EAST INTO NORTHWESTERN PORTION OF THE BLACKSBURG FORECAST AREA THROUGH THE DAYBREAK HOURS BEFORE DISSIPATING EAST OF THE BLUE RIDGE BY MID MORNING AS AREA ENCOUNTERS INCREASINGLY DOWNSLOPE FLOW. OTHERWISE...EXPECT TO SEE ANY EARLY MORNING FOG IN MOUNTAIN VALLEYS...AND ACROSS SOUTHSIDE VA INTO NORTH CENTRAL NC IN VICINITY OF OLD FRONTAL BOUNDARY RAPIDLY DISSIPATE WITH ONSET OF DAYTIME HEATING. TRICKY FORECAST FOR REST OF TODAY AS A COMBINATION OF WEATHER FEATURES COMPETE FOR ATTENTION. WIDESPREAD AREA OF SHOWERS CURRENTLY OVER OH VALLEY ASSOCIATED WITH FIRST IN SERIES OF SHORT WAVE TROFS THAT WILL PROGRESSIVELY CARVE OUT UPPER TROF OVER THE NORTHEASTERN PORTION OF THE NATION THIS WEEKEND...DRIVING COOL FRONT INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. LOCAL WRF AND HRRR MODELS INDICATING THAT PRECEDING AREA OF SHOWERS MAY HELP GENERATE AND PUSH OUTFLOW BOUNDARY SOUTHEAST OUT AHEAD OF THE FRONT INTO NORTHERN THIRD OF THE BLACKSBURG FORECAST AREA THIS AFTERNOON. DESPITE RATHER LACKLUSTER MID LEVEL INSTABILITY...AND POTENTIAL OF AT LEAST SOME OFFSET OF INSOLATIVE POTENTIAL DUE TO LINGERING MID AND HIGH LEVEL CLOUDS...WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED TO DEVELOP BY/DURING THE EARLY TO MID AFTERNOON IN ASSOCIATED CONFLUENCE ZONE... ESPECIALLY NORTH OF HIGHWAY 460...AND ACROSS WESTERN FLANKS OF THE APPALACHIANS AS WESTERLY UPSLOPING WINDS PROVIDE SOME NEEDED UPWARD ASSIST. MUCH BETTER INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VA INTO NORTH CENTRAL NC WHERE MUCH DEEPER LOW LEVEL/TROPICAL MOISTURE RESIDES IN VICINITY OF OLD FRONT. SHORT RANGE AND MESOSCALE MODELS HIGHLIGHT THIS AREA FOR ADDITIONAL SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ALTHOUGH ANY NORTHWARD PUSH OF THIS AIRMASS INTO VA APPEARS UNLIKELY CONSIDERING SLOW VEERING OF WINDS AS ZONAL FLOW INCREASES OVER AREA. IN LIGHT OF THE ABOVE...BEST THREAT FOR WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS TODAY WILL BE ACROSS THE NORTH...NORTHWEST...AND SOUTHEAST PORTION OF THE BLACKSBURG FORECAST AREA...WITH RELATIVE MINIMUM (MORE ISOLATED) THREAT FROM THE FOOTHILLS OF NORTHWEST NC NORTHEAST TOWARD FARMVILLE VA. SEVERE WEATHER THREAT AT THE PRESENT TIME APPEARS TO BE REMOTE. LOSS OF DAYTIME HEATING AND LITTLE TO NO DYNAMIC SUPPORT AS SHORT WAVE ENERGY REMAINS WELL NORTH OF THE BLACKSBURG AREA SHOULD SUPPORT DEMISE OF LINGERING SHOWER/THUNDERSTORM ACTIVITY IN MOST AREAS BEFORE MIDNIGHT TONIGHT...BUT WITH A LOW THREAT OF SOME STRAY SHOWERS REMAINING INTO THE EARLY MORNING HOURS ACROSS THE SOUTHWESTERN MOUNTAINS WHERE A BIT DEEPER MOISTURE PROFILE WILL RESIDE AS COLDER AIR FOLDS INTO AREA FROM THE NORTH. MOS GUIDANCE GENERALLY ACCEPTED FOR THE NEAR TERM PERIOD...WITH HIGHS TODAY IN THE 70S ACROSS THE HIGHER TERRAIN TO 80S ELSEWHERE...WITH OVERNIGHT LOWS MAINLY IN THE 60S EXCLUDING SOME MID TO UPPER 50S IN SOME OF THE DEEPER MOUNTAIN VALLEYS. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 430 AM EDT SATURDAY... A BRIEF AMPLIFICATION OF THE NW FLOW ALOFT WILL ALLOW A FAIRLY SUBSTANTIAL AREA OF COOL...DRY HIGH PRESSURE TO SPREAD SE ACROSS THE REGION BEHIND A COLD FRONT WHICH WILL PUSH INTO SOUTH CAROLINA BEFORE STALLING MONDAY. THIS WILL PROVIDE THE FORECAST AREA WITH A RESPITE FROM THE INCESSANT SHRA/TSRA ACTIVITY OF RECENT DAYS AND ALLOW A QUITE DRY AIR MASS TO SPREAD THROUGH THE AREA BY EARLY MON. ANY REMNANT -SHRA AROUND DAYBREAK SUN...SHOULD DISSIPATE QUICKLY AND SKIES SHOULD CLEAR EAST OF THE ALLEGHANYS. CANNOT RULE OUT LINGERING UPSLOPE SC ACROSS SE WV...BUT OVERALL EVEN THOSE AREAS SHOULD CLEAR OUT BY EVENING. TEMPS SUN SHOULD BE BELOW NORMAL WEST OF THE ALLEGHANYS...BUT NEAR NORMAL ACROSS THE PIEDMONT FROM STRONG INSOLATION AND DOWNSLOPE NW FLOW. MON MORNING SHOULD BE THE COOLEST MORNING OF THE NEXT SEVEN DAYS AND RIVAL THE RECENT PAST COUPLE OF COOL SPELLS WHERE MIN TEMPS DIPPED INTO THE UPPER 40S IN DEEPER MOUNTAIN VALLEYS WITH WIDESPREAD 50S WEST OF THE BLUE RIDGE...LOWER 60S ACROSS THE PIEDMONT. FOR TUE...THE FIRST IN A LONG SERIES OF NW FLOW DISTURBANCES TRACKS ACROSS THE REGION AS A PRONOUNCED BAROCLINIC ZONE BEGINS TO SET UP ACROSS THE REGION FROM NW-SE FROM THE OHIO VALLEY TOWARD THE MID-ATLANTIC...BEGINNING WHAT SHOULD BE A 3-5 DAY PERIOD OF QUITE ACTIVE CONVECTIVE WEATHER. FOR TUE...SFC MOISTURE WILL JUST BE RECOVERING...SO NOT EXPECTING AN OVERLY ACTIVE CONVECTIVE DAY JUST YET. THE MON SFC HIGH WILL MOVE TO A POSITION OFF THE MID- ATLANTIC COAST AND ALLOW A WEAK WEDGE SITUATION TO EVOLVE EAST OF THE BLUE RIDGE. FOR NOW...HAVE ADVERTISED LOW CHC POPS MOST AREAS...BUT THE BEST THREAT FOR PCPN APPEARS TO BE EAST OF OR NEAR THE ALLEGHANYS AT THIS TIME WHERE LOW-LEVEL MOISTURE CONVERGENCE AND SFC TD IS MAXIMIZED AND DIFFERENTIAL HEATING MAY HELP SPARK INITIAL CONVECTION DURING THE AFTERNOON. MAX/MIN TEMPS WILL BEGIN TO RECOVER FROM THE MON COOL SPELL AND SHOULD BE CLOSER TO NORMAL...EXCEPT STILL SLIGHTLY BELOW NORMAL IN THE FAR N-NW PART OF THE CWA. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 445 AM EDT SATURDAY... AS NOTED THE PAST SEVERAL DAYS...THIS PERIOD LOOKS TO BE QUITE ACTIVE WITH REGARD TO CONVECTION. THE FLOW WILL TREND TOWARD AN INCREASINGLY ZONAL FLOW WITH A SERIES OF EMBEDDED DISTURBANCES ALOFT. A WEAK COLD FRONT WILL BEGIN TO ENTER THE NW PART OF THE CWA BY THU...THEN ATTEMPT TO PUSH SLOWLY SOUTHEASTWARD THU-FRI. HOW FAR S-SE THE FRONT MOVES BEFORE STALLING IS HIGHLY QUESTIONABLE GIVEN THE INCREASING ZONAL FLOW IN PLACE AND A SUBTROPICAL RIDGE BUILDING ACROSS THE SE STATES. BOTH THE GFS AND ECMWF TRY TO PUSH THE FRONT COMPLETELY SOUTH OF OUR CWA BY SATURDAY AS IT STRENGTHENS THE NW FLOW JUST ENOUGH TO DO SO...BUT AS NOTED...THAT IS SOMEWHAT DOUBTFUL. AT ANY RATE...WED-THU LOOK QUITE ACTIVE AND PROBLEMATIC...ESPECIALLY IN TERMS OF FLASH FLOOD POTENTIAL. PWATS REACH OR EXCEED 2.0 INCHES ACROSS MUCH OF THE CWA WED- THU AFTERNOON. THIS COMBINED WITH PERIODIC AMPLE UPPER SUPPORT FROM EMBEDDED SHORT WAVES AND THE VERY WET ANTECEDENT CONDITIONS WILL HAVE TO BE WATCHED VERY CAREFULLY. WITH A NEARLY STALLED OR QUASI- STATIONARY FRONTAL BOUNDARY DRAPED ACROSS THE REGION AND FAVORABLE SUPPORT...TRAINING OF SHRA/TSRA ACTIVITY APPEARS LIKELY. FURTHERMORE...INSTABILITY LOOKS QUITE HEALTHY WITH CAPES REACHING 2000 J/KG OR GREATER WED AND THU AFTERNOON ACROSS MUCH OF THE CWA. THUS...A FEW STRONG TO SEVERE THUNDERSTORMS ALSO APPEAR LIKELY. HAVE INTRODUCED THE MENTION OF HEAVY RAIN TO THE ZFP FOR THESE PERIODS AND WILL ALSO CONTINUE TO INCLUDE THE THREAT OF HEAVY RAIN AND ISOLATED SEVERE IN THE HWO. HUMIDITY LEVELS WILL BE QUITE HIGH THROUGH THE EXTENDED PERIODS...SO THERE WILL BE LITTLE COOLING AT NIGHT. BY THE SAME TOKEN...MAX TEMPS SHOULD REMAIN NEAR NORMAL...PERHAPS SLIGHTLY BELOW IN AREAS THAT HAVE ENOUGH CLOUD COVER/PCPN TO LIMIT HEATING. NONETHELESS...IT WILL BE QUITE MUGGY AND MUCH MORE UNCOMFORTABLE THAN THE BEGINNING OF THE WEEK. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 730 AM EDT SATURDAY... FIRST BAND OF -SHRA ASSOCIATED WITH UPSTREAM TROUGH/FRONTAL SYSTEM HAS ALREADY PASSED THROUGH THE CWA. ONLY BLF REPORTED -RA AND A TRACE OF PCPN...AS EXPECTED MUCH WOULD BE LOST BECAUSE OF DOWNSLOPE EAST OF THE ALLEGHANYS. MAIN FRONTAL SYSTEM STILL BACK TO THE NORTH W-E ACROSS CENTRAL OH TO CENTRAL PA. SYNOPTIC SCALE MODELS SHOW LITTLE PCPN MAKING INTO OR CWA UNTIL LATE AFTERNOON/EVENING AND EVEN SOME OVERNIGHT INTO EARLY SUN. SFC-BL MOISTURE IS LACKING...SO FEEL THIS SYSTEM OVERALL WILL BE QUITE LACKLUSTER FOR OUR CWA. INSTABILITY IS LACKING...SO HAVE REMOVED MENTION OF VCTS EXCEPT FOR LYH AND DAN WHERE BETTER HEATING AND INSTABILITY COULD BE REALIZED BY AFTERNOON. OTHERWISE...HAVE JUST INCLUDED VCSH FOR NOW. CIGS SHOULD REMAIN VFR FOR THE MOST PART THROUGHOUT THE DAY AT ALL SITES. ANY EARLY MORNING FOG WILL DISSIPATE QUICKLY AFTER DAYBREAK...AND OVERALL THERE IS VERY LITTLE THIS MORNING ANYWAY BECAUSE OF THE EXTENSIVE MID/HIGH CLOUDS STREAMING ACROSS THE REGION. BULK OF ANY SHRA ACTIVITY SHOULD PASS THROUGH THE CWA IN THE 20Z NORTH TO 04Z SOUTH...WITH VERY LITTLE EXPECTED SW AREAS. OVERNIGHT...A FEW -SHRA MAY DEVELOP ACROSS WV AND MOVE TOWARD THE NEW RIVER/ROANOKE VALLEY BEFORE DISSIPATING. MOSTLY VFR CIGS EXPECTED WITH THIS ACTIVITY AS WELL. THE EXCEPTION TO CIGS OVERNIGHT WILL BE IN UPSLOPE AREAS OF SE WV...WHERE MVFR CIGS/MVFR VSBYS COULD DEVELOP FROM BLF- LWB...ESPECIALLY BLF AS TYPICAL WITH THIS SCENARIO. WINDS WSW 5-8KTS TODAY...BECOMING WNW-NW BEHIND THE FRONT OVERNIGHT AT SPEEDS OF 5-7KTS. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH TAF VALID PERIOD. HIGH CONFIDENCE IN WIND SPD/DIR THROUGH TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN LIMITED TSRA POTENTIAL THIS AFTERNOON/EVENING. EXTENDED AVIATION DISCUSSION... VFR CONDITIONS EXPECTED SUN-MON...OUTSIDE SOME EARLY MORNING MVFR CIGS SE WV SITES. SPOTTY AFTERNOON CONVECTION POSSIBLE TUE AFTERNOON...MAINLY LYH/DAN/ROA. WEDNESDAY THROUGH FRIDAY BRINGS WIDESPREAD CONVECTION BACK TO THE CWA...WITH ATTENDANT LOWER CIGS/VSBYS AS TROPICAL MOISTURE RETURNS TO THE AREA AND A QUASI- STATIONARY FRONTAL BOUNDARY DRIFTS SLOWLY SOUTHWARD THROUGH THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WERT NEAR TERM...KK/WERT SHORT TERM...RAB LONG TERM...RAB/WP AVIATION...RAB/WERT
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
957 AM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE AREA LATE TODAY INTO TONIGHT...PRECEDED AND ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. HIGH PRESSURE FOLLOWING THE FRONT WILL BRING DRIER AND COOLER AIR BACK INTO THE REGION SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 950 AM EDT SATURDAY... KFCX 88D LOOP SHOWED SCATTERED SHOWERS TRAVELING EAST ACROSS CWA THIS MORNING ASSOCIATED WITH ISENTROPIC LIFT. EXPANDED THE LIGHT POPS TO THE EAST THIS MORNING...AS THEY BATTLE THE DOWNSLOPE FLOW. RNK WRF ARW SHOWED SHOWERS WEAKENING WITH PROGRESSION EASTWARD. THIS MORNING 8AM/12Z RNK SOUNDING INDICATED THAT PWATS HAVE INCREASED TO 1.20 INCH WITH A WEST FLOW. SHORTWAVE TROF WILL DROP SOUTHEAST TODAY INTO TONIGHT. A COOL FRONT WILL MOVE INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. A COUPLE OF WEAK BOUNDARIES AHEAD OF THE FRONT MAY COMBINE WITH LIMITED INSTABILITY TO CREATE WIDELY SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING HELP BY CONFLUENCE ZONE. NAM AND WRF INDICATED THAT BEST INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VIRGINIA INTO NORTH CENTRAL NORTH CAROLINA WHERE MUCH DEEPER LOW LEVEL MOISTURE RESIDES IN VICINITY OF OLD FRONT. IF CLOUD COVER THINS ENOUGH...SCATTERED SHOWERS AND THUNDERSTORMS COULD DEVELOP BY LATE AFTERNOON IN SOUTHEASTERN PART OF FORECAST AREA. A STRONGER THUNDERSTORM COULD CONTAIN GUSTY WINDS AND HEAVY DOWNPOURS. SHOWERS AND THUNDERSTORMS THIS EVENING INTO TONIGHT WILL DIMINISH WITH THE LOSS OF SOLAR HEATING AS SHORTWAVE ENERGY REMAINS WELL NORTH OF US. MADE SOME MINOR ADJUSTMENTS TO POPS...TEMPERATURES AND CLOUD COVER IN ISC GRIDS. AS OF 355 AM EDT SATURDAY... SCATTERED SHOWERS CURRENTLY MOVING EAST OUT OF EASTERN KY AND WV ON NOSE OF ISENTROPIC LIFT ZONE MAXIMIZED IN 850-700 MILLIBAR LAYER...AND WILL LIKELY CONTINUE EAST INTO NORTHWESTERN PORTION OF THE BLACKSBURG FORECAST AREA THROUGH THE DAYBREAK HOURS BEFORE DISSIPATING EAST OF THE BLUE RIDGE BY MID MORNING AS AREA ENCOUNTERS INCREASINGLY DOWNSLOPE FLOW. OTHERWISE...EXPECT TO SEE ANY EARLY MORNING FOG IN MOUNTAIN VALLEYS...AND ACROSS SOUTHSIDE VA INTO NORTH CENTRAL NC IN VICINITY OF OLD FRONTAL BOUNDARY RAPIDLY DISSIPATE WITH ONSET OF DAYTIME HEATING. TRICKY FORECAST FOR REST OF TODAY AS A COMBINATION OF WEATHER FEATURES COMPETE FOR ATTENTION. WIDESPREAD AREA OF SHOWERS CURRENTLY OVER OH VALLEY ASSOCIATED WITH FIRST IN SERIES OF SHORT WAVE TROFS THAT WILL PROGRESSIVELY CARVE OUT UPPER TROF OVER THE NORTHEASTERN PORTION OF THE NATION THIS WEEKEND...DRIVING COOL FRONT INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. LOCAL WRF AND HRRR MODELS INDICATING THAT PRECEDING AREA OF SHOWERS MAY HELP GENERATE AND PUSH OUTFLOW BOUNDARY SOUTHEAST OUT AHEAD OF THE FRONT INTO NORTHERN THIRD OF THE BLACKSBURG FORECAST AREA THIS AFTERNOON. DESPITE RATHER LACKLUSTER MID LEVEL INSTABILITY...AND POTENTIAL OF AT LEAST SOME OFFSET OF INSOLATIVE POTENTIAL DUE TO LINGERING MID AND HIGH LEVEL CLOUDS...WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED TO DEVELOP BY/DURING THE EARLY TO MID AFTERNOON IN ASSOCIATED CONFLUENCE ZONE... ESPECIALLY NORTH OF HIGHWAY 460...AND ACROSS WESTERN FLANKS OF THE APPALACHIANS AS WESTERLY UPSLOPING WINDS PROVIDE SOME NEEDED UPWARD ASSIST. MUCH BETTER INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VA INTO NORTH CENTRAL NC WHERE MUCH DEEPER LOW LEVEL/TROPICAL MOISTURE RESIDES IN VICINITY OF OLD FRONT. SHORT RANGE AND MESOSCALE MODELS HIGHLIGHT THIS AREA FOR ADDITIONAL SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ALTHOUGH ANY NORTHWARD PUSH OF THIS AIRMASS INTO VA APPEARS UNLIKELY CONSIDERING SLOW VEERING OF WINDS AS ZONAL FLOW INCREASES OVER AREA. IN LIGHT OF THE ABOVE...BEST THREAT FOR WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS TODAY WILL BE ACROSS THE NORTH...NORTHWEST...AND SOUTHEAST PORTION OF THE BLACKSBURG FORECAST AREA...WITH RELATIVE MINIMUM (MORE ISOLATED) THREAT FROM THE FOOTHILLS OF NORTHWEST NC NORTHEAST TOWARD FARMVILLE VA. SEVERE WEATHER THREAT AT THE PRESENT TIME APPEARS TO BE REMOTE. LOSS OF DAYTIME HEATING AND LITTLE TO NO DYNAMIC SUPPORT AS SHORT WAVE ENERGY REMAINS WELL NORTH OF THE BLACKSBURG AREA SHOULD SUPPORT DEMISE OF LINGERING SHOWER/THUNDERSTORM ACTIVITY IN MOST AREAS BEFORE MIDNIGHT TONIGHT...BUT WITH A LOW THREAT OF SOME STRAY SHOWERS REMAINING INTO THE EARLY MORNING HOURS ACROSS THE SOUTHWESTERN MOUNTAINS WHERE A BIT DEEPER MOISTURE PROFILE WILL RESIDE AS COLDER AIR FOLDS INTO AREA FROM THE NORTH. MOS GUIDANCE GENERALLY ACCEPTED FOR THE NEAR TERM PERIOD...WITH HIGHS TODAY IN THE 70S ACROSS THE HIGHER TERRAIN TO 80S ELSEWHERE...WITH OVERNIGHT LOWS MAINLY IN THE 60S EXCLUDING SOME MID TO UPPER 50S IN SOME OF THE DEEPER MOUNTAIN VALLEYS. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 430 AM EDT SATURDAY... A BRIEF AMPLIFICATION OF THE NW FLOW ALOFT WILL ALLOW A FAIRLY SUBSTANTIAL AREA OF COOL...DRY HIGH PRESSURE TO SPREAD SE ACROSS THE REGION BEHIND A COLD FRONT WHICH WILL PUSH INTO SOUTH CAROLINA BEFORE STALLING MONDAY. THIS WILL PROVIDE THE FORECAST AREA WITH A RESPITE FROM THE INCESSANT SHRA/TSRA ACTIVITY OF RECENT DAYS AND ALLOW A QUITE DRY AIR MASS TO SPREAD THROUGH THE AREA BY EARLY MON. ANY REMNANT -SHRA AROUND DAYBREAK SUN...SHOULD DISSIPATE QUICKLY AND SKIES SHOULD CLEAR EAST OF THE ALLEGHANYS. CANNOT RULE OUT LINGERING UPSLOPE SC ACROSS SE WV...BUT OVERALL EVEN THOSE AREAS SHOULD CLEAR OUT BY EVENING. TEMPS SUN SHOULD BE BELOW NORMAL WEST OF THE ALLEGHANYS...BUT NEAR NORMAL ACROSS THE PIEDMONT FROM STRONG INSOLATION AND DOWNSLOPE NW FLOW. MON MORNING SHOULD BE THE COOLEST MORNING OF THE NEXT SEVEN DAYS AND RIVAL THE RECENT PAST COUPLE OF COOL SPELLS WHERE MIN TEMPS DIPPED INTO THE UPPER 40S IN DEEPER MOUNTAIN VALLEYS WITH WIDESPREAD 50S WEST OF THE BLUE RIDGE...LOWER 60S ACROSS THE PIEDMONT. FOR TUE...THE FIRST IN A LONG SERIES OF NW FLOW DISTURBANCES TRACKS ACROSS THE REGION AS A PRONOUNCED BAROCLINIC ZONE BEGINS TO SET UP ACROSS THE REGION FROM NW-SE FROM THE OHIO VALLEY TOWARD THE MID-ATLANTIC...BEGINNING WHAT SHOULD BE A 3-5 DAY PERIOD OF QUITE ACTIVE CONVECTIVE WEATHER. FOR TUE...SFC MOISTURE WILL JUST BE RECOVERING...SO NOT EXPECTING AN OVERLY ACTIVE CONVECTIVE DAY JUST YET. THE MON SFC HIGH WILL MOVE TO A POSITION OFF THE MID- ATLANTIC COAST AND ALLOW A WEAK WEDGE SITUATION TO EVOLVE EAST OF THE BLUE RIDGE. FOR NOW...HAVE ADVERTISED LOW CHC POPS MOST AREAS...BUT THE BEST THREAT FOR PCPN APPEARS TO BE EAST OF OR NEAR THE ALLEGHANYS AT THIS TIME WHERE LOW-LEVEL MOISTURE CONVERGENCE AND SFC TD IS MAXIMIZED AND DIFFERENTIAL HEATING MAY HELP SPARK INITIAL CONVECTION DURING THE AFTERNOON. MAX/MIN TEMPS WILL BEGIN TO RECOVER FROM THE MON COOL SPELL AND SHOULD BE CLOSER TO NORMAL...EXCEPT STILL SLIGHTLY BELOW NORMAL IN THE FAR N-NW PART OF THE CWA. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 445 AM EDT SATURDAY... AS NOTED THE PAST SEVERAL DAYS...THIS PERIOD LOOKS TO BE QUITE ACTIVE WITH REGARD TO CONVECTION. THE FLOW WILL TREND TOWARD AN INCREASINGLY ZONAL FLOW WITH A SERIES OF EMBEDDED DISTURBANCES ALOFT. A WEAK COLD FRONT WILL BEGIN TO ENTER THE NW PART OF THE CWA BY THU...THEN ATTEMPT TO PUSH SLOWLY SOUTHEASTWARD THU-FRI. HOW FAR S-SE THE FRONT MOVES BEFORE STALLING IS HIGHLY QUESTIONABLE GIVEN THE INCREASING ZONAL FLOW IN PLACE AND A SUBTROPICAL RIDGE BUILDING ACROSS THE SE STATES. BOTH THE GFS AND ECMWF TRY TO PUSH THE FRONT COMPLETELY SOUTH OF OUR CWA BY SATURDAY AS IT STRENGTHENS THE NW FLOW JUST ENOUGH TO DO SO...BUT AS NOTED...THAT IS SOMEWHAT DOUBTFUL. AT ANY RATE...WED-THU LOOK QUITE ACTIVE AND PROBLEMATIC...ESPECIALLY IN TERMS OF FLASH FLOOD POTENTIAL. PWATS REACH OR EXCEED 2.0 INCHES ACROSS MUCH OF THE CWA WED- THU AFTERNOON. THIS COMBINED WITH PERIODIC AMPLE UPPER SUPPORT FROM EMBEDDED SHORT WAVES AND THE VERY WET ANTECEDENT CONDITIONS WILL HAVE TO BE WATCHED VERY CAREFULLY. WITH A NEARLY STALLED OR QUASI- STATIONARY FRONTAL BOUNDARY DRAPED ACROSS THE REGION AND FAVORABLE SUPPORT...TRAINING OF SHRA/TSRA ACTIVITY APPEARS LIKELY. FURTHERMORE...INSTABILITY LOOKS QUITE HEALTHY WITH CAPES REACHING 2000 J/KG OR GREATER WED AND THU AFTERNOON ACROSS MUCH OF THE CWA. THUS...A FEW STRONG TO SEVERE THUNDERSTORMS ALSO APPEAR LIKELY. HAVE INTRODUCED THE MENTION OF HEAVY RAIN TO THE ZFP FOR THESE PERIODS AND WILL ALSO CONTINUE TO INCLUDE THE THREAT OF HEAVY RAIN AND ISOLATED SEVERE IN THE HWO. HUMIDITY LEVELS WILL BE QUITE HIGH THROUGH THE EXTENDED PERIODS...SO THERE WILL BE LITTLE COOLING AT NIGHT. BY THE SAME TOKEN...MAX TEMPS SHOULD REMAIN NEAR NORMAL...PERHAPS SLIGHTLY BELOW IN AREAS THAT HAVE ENOUGH CLOUD COVER/PCPN TO LIMIT HEATING. NONETHELESS...IT WILL BE QUITE MUGGY AND MUCH MORE UNCOMFORTABLE THAN THE BEGINNING OF THE WEEK. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... AS OF 730 AM EDT SATURDAY... FIRST BAND OF -SHRA ASSOCIATED WITH UPSTREAM TROUGH/FRONTAL SYSTEM HAS ALREADY PASSED THROUGH THE CWA. ONLY BLF REPORTED -RA AND A TRACE OF PCPN...AS EXPECTED MUCH WOULD BE LOST BECAUSE OF DOWNSLOPE EAST OF THE ALLEGHANYS. MAIN FRONTAL SYSTEM STILL BACK TO THE NORTH W-E ACROSS CENTRAL OH TO CENTRAL PA. SYNOPTIC SCALE MODELS SHOW LITTLE PCPN MAKING INTO OR CWA UNTIL LATE AFTERNOON/EVENING AND EVEN SOME OVERNIGHT INTO EARLY SUN. SFC-BL MOISTURE IS LACKING...SO FEEL THIS SYSTEM OVERALL WILL BE QUITE LACKLUSTER FOR OUR CWA. INSTABILITY IS LACKING...SO HAVE REMOVED MENTION OF VCTS EXCEPT FOR LYH AND DAN WHERE BETTER HEATING AND INSTABILITY COULD BE REALIZED BY AFTERNOON. OTHERWISE...HAVE JUST INCLUDED VCSH FOR NOW. CIGS SHOULD REMAIN VFR FOR THE MOST PART THROUGHOUT THE DAY AT ALL SITES. ANY EARLY MORNING FOG WILL DISSIPATE QUICKLY AFTER DAYBREAK...AND OVERALL THERE IS VERY LITTLE THIS MORNING ANYWAY BECAUSE OF THE EXTENSIVE MID/HIGH CLOUDS STREAMING ACROSS THE REGION. BULK OF ANY SHRA ACTIVITY SHOULD PASS THROUGH THE CWA IN THE 20Z NORTH TO 04Z SOUTH...WITH VERY LITTLE EXPECTED SW AREAS. OVERNIGHT...A FEW -SHRA MAY DEVELOP ACROSS WV AND MOVE TOWARD THE NEW RIVER/ROANOKE VALLEY BEFORE DISSIPATING. MOSTLY VFR CIGS EXPECTED WITH THIS ACTIVITY AS WELL. THE EXCEPTION TO CIGS OVERNIGHT WILL BE IN UPSLOPE AREAS OF SE WV...WHERE MVFR CIGS/MVFR VSBYS COULD DEVELOP FROM BLF- LWB...ESPECIALLY BLF AS TYPICAL WITH THIS SCENARIO. WINDS WSW 5-8KTS TODAY...BECOMING WNW-NW BEHIND THE FRONT OVERNIGHT AT SPEEDS OF 5-7KTS. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH TAF VALID PERIOD. HIGH CONFIDENCE IN WIND SPD/DIR THROUGH TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN LIMITED TSRA POTENTIAL THIS AFTERNOON/EVENING. EXTENDED AVIATION DISCUSSION... VFR CONDITIONS EXPECTED SUN-MON...OUTSIDE SOME EARLY MORNING MVFR CIGS SE WV SITES. SPOTTY AFTERNOON CONVECTION POSSIBLE TUE AFTERNOON...MAINLY LYH/DAN/ROA. WEDNESDAY THROUGH FRIDAY BRINGS WIDESPREAD CONVECTION BACK TO THE CWA...WITH ATTENDANT LOWER CIGS/VSBYS AS TROPICAL MOISTURE RETURNS TO THE AREA AND A QUASI- STATIONARY FRONTAL BOUNDARY DRIFTS SLOWLY SOUTHWARD THROUGH THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WERT NEAR TERM...KK/WERT SHORT TERM...RAB LONG TERM...RAB/WP AVIATION...RAB/WERT
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
750 AM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE AREA LATE TODAY INTO TONIGHT...PRECEDED AND ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. HIGH PRESSURE FOLLOWING THE FRONT WILL BRING DRIER AND COOLER AIR BACK INTO THE REGION SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 355 AM EDT SATURDAY... SCATTERED SHOWERS CURRENTLY MOVING EAST OUT OF EASTERN KY AND WV ON NOSE OF ISENTROPIC LIFT ZONE MAXIMIZED IN 850-700 MILLIBAR LAYER...AND WILL LIKELY CONTINUE EAST INTO NORTHWESTERN PORTION OF THE BLACKSBURG FORECAST AREA THROUGH THE DAYBREAK HOURS BEFORE DISSIPATING EAST OF THE BLUE RIDGE BY MID MORNING AS AREA ENCOUNTERS INCREASINGLY DOWNSLOPE FLOW. OTHERWISE...EXPECT TO SEE ANY EARLY MORNING FOG IN MOUNTAIN VALLEYS...AND ACROSS SOUTHSIDE VA INTO NORTH CENTRAL NC IN VICINITY OF OLD FRONTAL BOUNDARY RAPIDLY DISSIPATE WITH ONSET OF DAYTIME HEATING. TRICKY FORECAST FOR REST OF TODAY AS A COMBINATION OF WEATHER FEATURES COMPETE FOR ATTENTION. WIDESPREAD AREA OF SHOWERS CURRENTLY OVER OH VALLEY ASSOCIATED WITH FIRST IN SERIES OF SHORT WAVE TROFS THAT WILL PROGRESSIVELY CARVE OUT UPPER TROF OVER THE NORTHEASTERN PORTION OF THE NATION THIS WEEKEND...DRIVING COOL FRONT INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. LOCAL WRF AND HRRR MODELS INDICATING THAT PRECEDING AREA OF SHOWERS MAY HELP GENERATE AND PUSH OUTFLOW BOUNDARY SOUTHEAST OUT AHEAD OF THE FRONT INTO NORTHERN THIRD OF THE BLACKSBURG FORECAST AREA THIS AFTERNOON. DESPITE RATHER LACKLUSTER MID LEVEL INSTABILITY...AND POTENTIAL OF AT LEAST SOME OFFSET OF INSOLATIVE POTENTIAL DUE TO LINGERING MID AND HIGH LEVEL CLOUDS...WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED TO DEVELOP BY/DURING THE EARLY TO MID AFTERNOON IN ASSOCIATED CONFLUENCE ZONE... ESPECIALLY NORTH OF HIGHWAY 460...AND ACROSS WESTERN FLANKS OF THE APPALACHIANS AS WESTERLY UPSLOPING WINDS PROVIDE SOME NEEDED UPWARD ASSIST. MUCH BETTER INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VA INTO NORTH CENTRAL NC WHERE MUCH DEEPER LOW LEVEL/TROPICAL MOISTURE RESIDES IN VICINITY OF OLD FRONT. SHORT RANGE AND MESOSCALE MODELS HIGHLIGHT THIS AREA FOR ADDITIONAL SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ALTHOUGH ANY NORTHWARD PUSH OF THIS AIRMASS INTO VA APPEARS UNLIKELY CONSIDERING SLOW VEERING OF WINDS AS ZONAL FLOW INCREASES OVER AREA. IN LIGHT OF THE ABOVE...BEST THREAT FOR WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS TODAY WILL BE ACROSS THE NORTH...NORTHWEST...AND SOUTHEAST PORTION OF THE BLACKSBURG FORECAST AREA...WITH RELATIVE MINIMUM (MORE ISOLATED) THREAT FROM THE FOOTHILLS OF NORTHWEST NC NORTHEAST TOWARD FARMVILLE VA. SEVERE WEATHER THREAT AT THE PRESENT TIME APPEARS TO BE REMOTE. LOSS OF DAYTIME HEATING AND LITTLE TO NO DYNAMIC SUPPORT AS SHORT WAVE ENERGY REMAINS WELL NORTH OF THE BLACKSBURG AREA SHOULD SUPPORT DEMISE OF LINGERING SHOWER/THUNDERSTORM ACTIVITY IN MOST AREAS BEFORE MIDNIGHT TONIGHT...BUT WITH A LOW THREAT OF SOME STRAY SHOWERS REMAINING INTO THE EARLY MORNING HOURS ACROSS THE SOUTHWESTERN MOUNTAINS WHERE A BIT DEEPER MOISTURE PROFILE WILL RESIDE AS COLDER AIR FOLDS INTO AREA FROM THE NORTH. MOS GUIDANCE GENERALLY ACCEPTED FOR THE NEAR TERM PERIOD...WITH HIGHS TODAY IN THE 70S ACROSS THE HIGHER TERRAIN TO 80S ELSEWHERE...WITH OVERNIGHT LOWS MAINLY IN THE 60S EXCLUDING SOME MID TO UPPER 50S IN SOME OF THE DEEPER MOUNTAIN VALLEYS. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 430 AM EDT SATURDAY... A BRIEF AMPLIFICATION OF THE NW FLOW ALOFT WILL ALLOW A FAIRLY SUBSTANTIAL AREA OF COOL...DRY HIGH PRESSURE TO SPREAD SE ACROSS THE REGION BEHIND A COLD FRONT WHICH WILL PUSH INTO SOUTH CAROLINA BEFORE STALLING MONDAY. THIS WILL PROVIDE THE FORECAST AREA WITH A RESPITE FROM THE INCESSANT SHRA/TSRA ACTIVITY OF RECENT DAYS AND ALLOW A QUITE DRY AIR MASS TO SPREAD THROUGH THE AREA BY EARLY MON. ANY REMNANT -SHRA AROUND DAYBREAK SUN...SHOULD DISSIPATE QUICKLY AND SKIES SHOULD CLEAR EAST OF THE ALLEGHANYS. CANNOT RULE OUT LINGERING UPSLOPE SC ACROSS SE WV...BUT OVERALL EVEN THOSE AREAS SHOULD CLEAR OUT BY EVENING. TEMPS SUN SHOULD BE BELOW NORMAL WEST OF THE ALLEGHANYS...BUT NEAR NORMAL ACROSS THE PIEDMONT FROM STRONG INSOLATION AND DOWNSLOPE NW FLOW. MON MORNING SHOULD BE THE COOLEST MORNING OF THE NEXT SEVEN DAYS AND RIVAL THE RECENT PAST COUPLE OF COOL SPELLS WHERE MIN TEMPS DIPPED INTO THE UPPER 40S IN DEEPER MOUNTAIN VALLEYS WITH WIDESPREAD 50S WEST OF THE BLUE RIDGE...LOWER 60S ACROSS THE PIEDMONT. FOR TUE...THE FIRST IN A LONG SERIES OF NW FLOW DISTURBANCES TRACKS ACROSS THE REGION AS A PRONOUNCED BAROCLINIC ZONE BEGINS TO SET UP ACROSS THE REGION FROM NW-SE FROM THE OHIO VALLEY TOWARD THE MID-ATLANTIC...BEGINNING WHAT SHOULD BE A 3-5 DAY PERIOD OF QUITE ACTIVE CONVECTIVE WEATHER. FOR TUE...SFC MOISTURE WILL JUST BE RECOVERING...SO NOT EXPECTING AN OVERLY ACTIVE CONVECTIVE DAY JUST YET. THE MON SFC HIGH WILL MOVE TO A POSITION OFF THE MID- ATLANTIC COAST AND ALLOW A WEAK WEDGE SITUATION TO EVOLVE EAST OF THE BLUE RIDGE. FOR NOW...HAVE ADVERTISED LOW CHC POPS MOST AREAS...BUT THE BEST THREAT FOR PCPN APPEARS TO BE EAST OF OR NEAR THE ALLEGHANYS AT THIS TIME WHERE LOW-LEVEL MOISTURE CONVERGENCE AND SFC TD IS MAXIMIZED AND DIFFERENTIAL HEATING MAY HELP SPARK INITIAL CONVECTION DURING THE AFTERNOON. MAX/MIN TEMPS WILL BEGIN TO RECOVER FROM THE MON COOL SPELL AND SHOULD BE CLOSER TO NORMAL...EXCEPT STILL SLIGHTLY BELOW NORMAL IN THE FAR N-NW PART OF THE CWA. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 445 AM EDT SATURDAY... AS NOTED THE PAST SEVERAL DAYS...THIS PERIOD LOOKS TO BE QUITE ACTIVE WITH REGARD TO CONVECTION. THE FLOW WILL TREND TOWARD AN INCREASINGLY ZONAL FLOW WITH A SERIES OF EMBEDDED DISTURBANCES ALOFT. A WEAK COLD FRONT WILL BEGIN TO ENTER THE NW PART OF THE CWA BY THU...THEN ATTEMPT TO PUSH SLOWLY SOUTHEASTWARD THU-FRI. HOW FAR S-SE THE FRONT MOVES BEFORE STALLING IS HIGHLY QUESTIONABLE GIVEN THE INCREASING ZONAL FLOW IN PLACE AND A SUBTROPICAL RIDGE BUILDING ACROSS THE SE STATES. BOTH THE GFS AND ECMWF TRY TO PUSH THE FRONT COMPLETELY SOUTH OF OUR CWA BY SATURDAY AS IT STRENGTHENS THE NW FLOW JUST ENOUGH TO DO SO...BUT AS NOTED...THAT IS SOMEWHAT DOUBTFUL. AT ANY RATE...WED-THU LOOK QUITE ACTIVE AND PROBLEMATIC...ESPECIALLY IN TERMS OF FLASH FLOOD POTENTIAL. PWATS REACH OR EXCEED 2.0 INCHES ACROSS MUCH OF THE CWA WED- THU AFTERNOON. THIS COMBINED WITH PERIODIC AMPLE UPPER SUPPORT FROM EMBEDDED SHORT WAVES AND THE VERY WET ANTECEDENT CONDITIONS WILL HAVE TO BE WATCHED VERY CAREFULLY. WITH A NEARLY STALLED OR QUASI- STATIONARY FRONTAL BOUNDARY DRAPED ACROSS THE REGION AND FAVORABLE SUPPORT...TRAINING OF SHRA/TSRA ACTIVITY APPEARS LIKELY. FURTHERMORE...INSTABILITY LOOKS QUITE HEALTHY WITH CAPES REACHING 2000 J/KG OR GREATER WED AND THU AFTERNOON ACROSS MUCH OF THE CWA. THUS...A FEW STRONG TO SEVERE THUNDERSTORMS ALSO APPEAR LIKELY. HAVE INTRODUCED THE MENTION OF HEAVY RAIN TO THE ZFP FOR THESE PERIODS AND WILL ALSO CONTINUE TO INCLUDE THE THREAT OF HEAVY RAIN AND ISOLATED SEVERE IN THE HWO. HUMIDITY LEVELS WILL BE QUITE HIGH THROUGH THE EXTENDED PERIODS...SO THERE WILL BE LITTLE COOLING AT NIGHT. BY THE SAME TOKEN...MAX TEMPS SHOULD REMAIN NEAR NORMAL...PERHAPS SLIGHTLY BELOW IN AREAS THAT HAVE ENOUGH CLOUD COVER/PCPN TO LIMIT HEATING. NONETHELESS...IT WILL BE QUITE MUGGY AND MUCH MORE UNCOMFORTABLE THAN THE BEGINNING OF THE WEEK. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 730 AM EDT SATURDAY... FIRST BAND OF -SHRA ASSOCIATED WITH UPSTREAM TROUGH/FRONTAL SYSTEM HAS ALREADY PASSED THROUGH THE CWA. ONLY BLF REPORTED -RA AND A TRACE OF PCPN...AS EXPECTED MUCH WOULD BE LOST BECAUSE OF DOWNSLOPE EAST OF THE ALLEGHANYS. MAIN FRONTAL SYSTEM STILL BACK TO THE NORTH W-E ACROSS CENTRAL OH TO CENTRAL PA. SYNOPTIC SCALE MODELS SHOW LITTLE PCPN MAKING INTO OR CWA UNTIL LATE AFTERNOON/EVENING AND EVEN SOME OVERNIGHT INTO EARLY SUN. SFC-BL MOISTURE IS LACKING...SO FEEL THIS SYSTEM OVERALL WILL BE QUITE LACKLUSTER FOR OUR CWA. INSTABILITY IS LACKING...SO HAVE REMOVED MENTION OF VCTS EXCEPT FOR LYH AND DAN WHERE BETTER HEATING AND INSTABILITY COULD BE REALIZED BY AFTERNOON. OTHERWISE...HAVE JUST INCLUDED VCSH FOR NOW. CIGS SHOULD REMAIN VFR FOR THE MOST PART THROUGHOUT THE DAY AT ALL SITES. ANY EARLY MORNING FOG WILL DISSIPATE QUICKLY AFTER DAYBREAK...AND OVERALL THERE IS VERY LITTLE THIS MORNING ANYWAY BECAUSE OF THE EXTENSIVE MID/HIGH CLOUDS STREAMING ACROSS THE REGION. BULK OF ANY SHRA ACTIVITY SHOULD PASS THROUGH THE CWA IN THE 20Z NORTH TO 04Z SOUTH...WITH VERY LITTLE EXPECTED SW AREAS. OVERNIGHT...A FEW -SHRA MAY DEVELOP ACROSS WV AND MOVE TOWARD THE NEW RIVER/ROANOKE VALLEY BEFORE DISSIPATING. MOSTLY VFR CIGS EXPECTED WITH THIS ACTIVITY AS WELL. THE EXCEPTION TO CIGS OVERNIGHT WILL BE IN UPSLOPE AREAS OF SE WV...WHERE MVFR CIGS/MVFR VSBYS COULD DEVELOP FROM BLF- LWB...ESPECIALLY BLF AS TYPICAL WITH THIS SCENARIO. WINDS WSW 5-8KTS TODAY...BECOMING WNW-NW BEHIND THE FRONT OVERNIGHT AT SPEEDS OF 5-7KTS. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH TAF VALID PERIOD. HIGH CONFIDENCE IN WIND SPD/DIR THROUGH TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN LIMITED TSRA POTENTIAL THIS AFTERNOON/EVENING. EXTENDED AVIATION DISCUSSION... VFR CONDITIONS EXPECTED SUN-MON...OUTSIDE SOME EARLY MORNING MVFR CIGS SE WV SITES. SPOTTY AFTERNOON CONVECTION POSSIBLE TUE AFTERNOON...MAINLY LYH/DAN/ROA. WEDNESDAY THROUGH FRIDAY BRINGS WIDESPREAD CONVECTION BACK TO THE CWA...WITH ATTENDANT LOWER CIGS/VSBYS AS TROPICAL MOISTURE RETURNS TO THE AREA AND A QUASI- STATIONARY FRONTAL BOUNDARY DRIFTS SLOWLY SOUTHWARD THROUGH THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WERT NEAR TERM...WERT SHORT TERM...RAB LONG TERM...RAB/WP AVIATION...RAB/WERT
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
459 AM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE AREA LATE TODAY INTO TONIGHT...PRECEDED AND ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. HIGH PRESSURE FOLLOWING THE FRONT WILL BRING DRIER AND COOLER AIR BACK INTO THE REGION SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 355 AM EDT SATURDAY... SCATTERED SHOWERS CURRENTLY MOVING EAST OUT OF EASTERN KY AND WV ON NOSE OF ISENTROPIC LIFT ZONE MAXIMIZED IN 850-700 MILLIBAR LAYER...AND WILL LIKELY CONTINUE EAST INTO NORTHWESTERN PORTION OF THE BLACKSBURG FORECAST AREA THROUGH THE DAYBREAK HOURS BEFORE DISSIPATING EAST OF THE BLUE RIDGE BY MID MORNING AS AREA ENCOUNTERS INCREASINGLY DOWNSLOPE FLOW. OTHERWISE...EXPECT TO SEE ANY EARLY MORNING FOG IN MOUNTAIN VALLEYS...AND ACROSS SOUTHSIDE VA INTO NORTH CENTRAL NC IN VICINITY OF OLD FRONTAL BOUNDARY RAPIDLY DISSIPATE WITH ONSET OF DAYTIME HEATING. TRICKY FORECAST FOR REST OF TODAY AS A COMBINATION OF WEATHER FEATURES COMPETE FOR ATTENTION. WIDESPREAD AREA OF SHOWERS CURRENTLY OVER OH VALLEY ASSOCIATED WITH FIRST IN SERIES OF SHORT WAVE TROFS THAT WILL PROGRESSIVELY CARVE OUT UPPER TROF OVER THE NORTHEASTERN PORTION OF THE NATION THIS WEEKEND...DRIVING COOL FRONT INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. LOCAL WRF AND HRRR MODELS INDICATING THAT PRECEDING AREA OF SHOWERS MAY HELP GENERATE AND PUSH OUTFLOW BOUNDARY SOUTHEAST OUT AHEAD OF THE FRONT INTO NORTHERN THIRD OF THE BLACKSBURG FORECAST AREA THIS AFTERNOON. DESPITE RATHER LACKLUSTER MID LEVEL INSTABILITY...AND POTENTIAL OF AT LEAST SOME OFFSET OF INSOLATIVE POTENTIAL DUE TO LINGERING MID AND HIGH LEVEL CLOUDS...WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED TO DEVELOP BY/DURING THE EARLY TO MID AFTERNOON IN ASSOCIATED CONFLUENCE ZONE... ESPECIALLY NORTH OF HIGHWAY 460...AND ACROSS WESTERN FLANKS OF THE APPALACHIANS AS WESTERLY UPSLOPING WINDS PROVIDE SOME NEEDED UPWARD ASSIST. MUCH BETTER INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VA INTO NORTH CENTRAL NC WHERE MUCH DEEPER LOW LEVEL/TROPICAL MOISTURE RESIDES IN VICINITY OF OLD FRONT. SHORT RANGE AND MESOSCALE MODELS HIGHLIGHT THIS AREA FOR ADDITIONAL SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ALTHOUGH ANY NORTHWARD PUSH OF THIS AIRMASS INTO VA APPEARS UNLIKELY CONSIDERING SLOW VEERING OF WINDS AS ZONAL FLOW INCREASES OVER AREA. IN LIGHT OF THE ABOVE...BEST THREAT FOR WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS TODAY WILL BE ACROSS THE NORTH...NORTHWEST...AND SOUTHEAST PORTION OF THE BLACKSBURG FORECAST AREA...WITH RELATIVE MINIMUM (MORE ISOLATED) THREAT FROM THE FOOTHILLS OF NORTHWEST NC NORTHEAST TOWARD FARMVILLE VA. SEVERE WEATHER THREAT AT THE PRESENT TIME APPEARS TO BE REMOTE. LOSS OF DAYTIME HEATING AND LITTLE TO NO DYNAMIC SUPPORT AS SHORT WAVE ENERGY REMAINS WELL NORTH OF THE BLACKSBURG AREA SHOULD SUPPORT DEMISE OF LINGERING SHOWER/THUNDERSTORM ACTIVITY IN MOST AREAS BEFORE MIDNIGHT TONIGHT...BUT WITH A LOW THREAT OF SOME STRAY SHOWERS REMAINING INTO THE EARLY MORNING HOURS ACROSS THE SOUTHWESTERN MOUNTAINS WHERE A BIT DEEPER MOISTURE PROFILE WILL RESIDE AS COLDER AIR FOLDS INTO AREA FROM THE NORTH. MOS GUIDANCE GENERALLY ACCEPTED FOR THE NEAR TERM PERIOD...WITH HIGHS TODAY IN THE 70S ACROSS THE HIGHER TERRAIN TO 80S ELSEWHERE...WITH OVERNIGHT LOWS MAINLY IN THE 60S EXCLUDING SOME MID TO UPPER 50S IN SOME OF THE DEEPER MOUNTAIN VALLEYS. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 430 AM EDT SATURDAY... A BRIEF AMPLIFICATION OF THE NW FLOW ALOFT WILL ALLOW A FAIRLY SUBSTANTIAL AREA OF COOL...DRY HIGH PRESSURE TO SPREAD SE ACROSS THE REGION BEHIND A COLD FRONT WHICH WILL PUSH INTO SOUTH CAROLINA BEFORE STALLING MONDAY. THIS WILL PROVIDE THE FORECAST AREA WITH A RESPITE FROM THE INCESSANT SHRA/TSRA ACTIVITY OF RECENT DAYS AND ALLOW A QUITE DRY AIR MASS TO SPREAD THROUGH THE AREA BY EARLY MON. ANY REMNANT -SHRA AROUND DAYBREAK SUN...SHOULD DISSIPATE QUICKLY AND SKIES SHOULD CLEAR EAST OF THE ALLEGHANYS. CANNOT RULE OUT LINGERING UPSLOPE SC ACROSS SE WV...BUT OVERALL EVEN THOSE AREAS SHOULD CLEAR OUT BY EVENING. TEMPS SUN SHOULD BE BELOW NORMAL WEST OF THE ALLEGHANYS...BUT NEAR NORMAL ACROSS THE PIEDMONT FROM STRONG INSOLATION AND DOWNSLOPE NW FLOW. MON MORNING SHOULD BE THE COOLEST MORNING OF THE NEXT SEVEN DAYS AND RIVAL THE RECENT PAST COUPLE OF COOL SPELLS WHERE MIN TEMPS DIPPED INTO THE UPPER 40S IN DEEPER MOUNTAIN VALLEYS WITH WIDESPREAD 50S WEST OF THE BLUE RIDGE...LOWER 60S ACROSS THE PIEDMONT. FOR TUE...THE FIRST IN A LONG SERIES OF NW FLOW DISTURBANCES TRACKS ACROSS THE REGION AS A PRONOUNCED BAROCLINIC ZONE BEGINS TO SET UP ACROSS THE REGION FROM NW-SE FROM THE OHIO VALLEY TOWARD THE MID-ATLANTIC...BEGINNING WHAT SHOULD BE A 3-5 DAY PERIOD OF QUITE ACTIVE CONVECTIVE WEATHER. FOR TUE...SFC MOISTURE WILL JUST BE RECOVERING...SO NOT EXPECTING AN OVERLY ACTIVE CONVECTIVE DAY JUST YET. THE MON SFC HIGH WILL MOVE TO A POSITION OFF THE MID- ATLANTIC COAST AND ALLOW A WEAK WEDGE SITUATION TO EVOLVE EAST OF THE BLUE RIDGE. FOR NOW...HAVE ADVERTISED LOW CHC POPS MOST AREAS...BUT THE BEST THREAT FOR PCPN APPEARS TO BE EAST OF OR NEAR THE ALLEGHANYS AT THIS TIME WHERE LOW-LEVEL MOISTURE CONVERGENCE AND SFC TD IS MAXIMIZED AND DIFFERENTIAL HEATING MAY HELP SPARK INITIAL CONVECTION DURING THE AFTERNOON. MAX/MIN TEMPS WILL BEGIN TO RECOVER FROM THE MON COOL SPELL AND SHOULD BE CLOSER TO NORMAL...EXCEPT STILL SLIGHTLY BELOW NORMAL IN THE FAR N-NW PART OF THE CWA. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 445 AM EDT SATURDAY... AS NOTED THE PAST SEVERAL DAYS...THIS PERIOD LOOKS TO BE QUITE ACTIVE WITH REGARD TO CONVECTION. THE FLOW WILL TREND TOWARD AN INCREASINGLY ZONAL FLOW WITH A SERIES OF EMBEDDED DISTURBANCES ALOFT. A WEAK COLD FRONT WILL BEGIN TO ENTER THE NW PART OF THE CWA BY THU...THEN ATTEMPT TO PUSH SLOWLY SOUTHEASTWARD THU-FRI. HOW FAR S-SE THE FRONT MOVES BEFORE STALLING IS HIGHLY QUESTIONABLE GIVEN THE INCREASING ZONAL FLOW IN PLACE AND A SUBTROPICAL RIDGE BUILDING ACROSS THE SE STATES. BOTH THE GFS AND ECMWF TRY TO PUSH THE FRONT COMPLETELY SOUTH OF OUR CWA BY SATURDAY AS IT STRENGTHENS THE NW FLOW JUST ENOUGH TO DO SO...BUT AS NOTED...THAT IS SOMEWHAT DOUBTFUL. AT ANY RATE...WED-THU LOOK QUITE ACTIVE AND PROBLEMATIC...ESPECIALLY IN TERMS OF FLASH FLOOD POTENTIAL. PWATS REACH OR EXCEED 2.0 INCHES ACROSS MUCH OF THE CWA WED- THU AFTERNOON. THIS COMBINED WITH PERIODIC AMPLE UPPER SUPPORT FROM EMBEDDED SHORT WAVES AND THE VERY WET ANTECEDENT CONDITIONS WILL HAVE TO BE WATCHED VERY CAREFULLY. WITH A NEARLY STALLED OR QUASI- STATIONARY FRONTAL BOUNDARY DRAPED ACROSS THE REGION AND FAVORABLE SUPPORT...TRAINING OF SHRA/TSRA ACTIVITY APPEARS LIKELY. FURTHERMORE...INSTABILITY LOOKS QUITE HEALTHY WITH CAPES REACHING 2000 J/KG OR GREATER WED AND THU AFTERNOON ACROSS MUCH OF THE CWA. THUS...A FEW STRONG TO SEVERE THUNDERSTORMS ALSO APPEAR LIKELY. HAVE INTRODUCED THE MENTION OF HEAVY RAIN TO THE ZFP FOR THESE PERIODS AND WILL ALSO CONTINUE TO INCLUDE THE THREAT OF HEAVY RAIN AND ISOLATED SEVERE IN THE HWO. HUMIDITY LEVELS WILL BE QUITE HIGH THROUGH THE EXTENDED PERIODS...SO THERE WILL BE LITTLE COOLING AT NIGHT. BY THE SAME TOKEN...MAX TEMPS SHOULD REMAIN NEAR NORMAL...PERHAPS SLIGHTLY BELOW IN AREAS THAT HAVE ENOUGH CLOUD COVER/PCPN TO LIMIT HEATING. NONETHELESS...IT WILL BE QUITE MUGGY AND MUCH MORE UNCOMFORTABLE THAN THE BEGINNING OF THE WEEK. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 AM EDT SATURDAY... VFR WEATHER EXPECTED AT ALL TERMINAL FORECAST SITES FOR THE REST OF TONIGHT INTO SATURDAY WITH EXCEPTION OF MOUNTAIN VALLEYS...SUCH AS AT KBCB AND KLWB...AND ACROSS SOUTHSIDE VA AT/NEAR KDAN WHERE PROXIMITY TO OLD FRONTAL BOUNDARY AND MUCH HIGHER DEW POINTS RESIDE...WHERE DEVELOPMENT OF PATCHY LATE NIGHT/EARLY MORNING FOG AND ASSOCIATED LOCALIZED FLIGHT RESTRICTIONS DOWN INTO THE IFR RANGE ARE LIKELY. FOG SHOULD RAPIDLY LIFT/MIX OUT BY 13Z/900 AM WITH ONSET OF DAYTIME HEATING. EARLY MORNING CONVECTION DEVELOPING OVER CENTRAL NC AS MOIST AIR TRIES TO MAKE A PUSH BACK TOWARD THE NORTH MAY MAKE AN ATTEMPT TO THREATEN KDAN TOWARD DAYBREAK...BUT CURRENT THINKING IS THAT ACTUAL FLIGHT IMPACT FROM TSRA WILL REMAIN SOUTH OF THE STATE LINE...BUT CLOSE ENOUGH TO WARRANT MORNING INCLUSION OF VCTS AT KDAN. APPROACH OF NEXT FRONTAL SYSTEM TO THE NORTH AND WEST...AND WEAK QUASI-STATIONARY WARM/MOIST BOUNDARY JUST TO THE SOUTH...COUPLED WITH INCREASING INSOLATION SHOULD BE SUFFICIENT TO SUPPORT THE DEVELOPMENT OF WIDELY SCATTERED SHOWERS/STORMS IN JUST ABOUT ALL AREAS THIS AFTERNOON INTO THIS EVENING...WITH ACTIVITY MAXIMIZED NORTH OF HIGHWAY 460...ACROSS THE WESTERN FLANKS OF THE APPALACHIANS...AND OUT ACROSS THE PIEDMONT MAINLY ALONG AND SOUTH OF THE VA/NC STATE LINE. ACTUAL THREAT OF TSRA AT ANY TERMINAL FORECAST POINT REMAINS TOO LOW TO WARRANT ANYTHING OTHER THAN VCTS INCLUSION AT THE PRESENT TIME...BUT WILL AMEND AS NECESSARY IF ANY PARTICULAR STORM THREATENS ANY OF THE AIRPORTS LATER TODAY. ONSET OF NIGHTTIME COOLING AND PASSAGE COOL FRONT SHOULD END THREAT OF SHOWERS/STORMS THIS EVENING IN MOST AREAS...WITH VFR WEATHER THEN EXPECTED TO PREDOMINATE SUNDAY INTO MONDAY (OTHER THAN TYPICAL LATE NIGHT/EARLY MORNING PATCHY FOG IN MOUNTAIN VALLEYS AND LOW LYING SHELTERED AREAS OF THE PIEDMONT) AS HIGH PRESSURE SETTLES INTO/OVER THE AREA. AFTERNOON CONVECTION EXPECTED TO RETURN TO THE AREA BY TUESDAY AFTERNOON AS SURFACE RIDGE MOVES OFF TO THE EAST AND AS SOUTHERLY WINDS RETURN TO THE REGION...BRINGING AN INCREASE OF LOW LEVEL MOISTURE. WEDNESDAY OFFERS THE HIGHEST THREAT FOR A MORE ORGANIZED SHRA/TSRA EVENT ALONG WITH ATTENDANT LOWER CIGS/VSBYS AS TROPICAL MOISTURE RETURNS TO THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WERT NEAR TERM...WERT SHORT TERM...RAB LONG TERM...RAB/WP AVIATION...CF/KK/WERT
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
403 AM EDT SAT AUG 3 2013 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE AREA LATE TODAY INTO TONIGHT...PRECEDED AND ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. HIGH PRESSURE FOLLOWING THE FRONT WILL BRING DRIER AND COOLER AIR BACK INTO THE REGION SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 355 AM EDT SATURDAY... SCATTERED SHOWERS CURRENTLY MOVING EAST OUT OF EASTERN KY AND WV ON NOSE OF ISENTROPIC LIFT ZONE MAXIMIZED IN 850-700 MILLIBAR LAYER...AND WILL LIKELY CONTINUE EAST INTO NORTHWESTERN PORTION OF THE BLACKSBURG FORECAST AREA THROUGH THE DAYBREAK HOURS BEFORE DISSIPATING EAST OF THE BLUE RIDGE BY MID MORNING AS AREA ENCOUNTERS INCREASINGLY DOWNSLOPE FLOW. OTHERWISE...EXPECT TO SEE ANY EARLY MORNING FOG IN MOUNTAIN VALLEYS...AND ACROSS SOUTHSIDE VA INTO NORTH CENTRAL NC IN VICINITY OF OLD FRONTAL BOUNDARY RAPIDLY DISSIPATE WITH ONSET OF DAYTIME HEATING. TRICKY FORECAST FOR REST OF TODAY AS A COMBINATION OF WEATHER FEATURES COMPETE FOR ATTENTION. WIDESPREAD AREA OF SHOWERS CURRENTLY OVER OH VALLEY ASSOCIATED WITH FIRST IN SERIES OF SHORT WAVE TROFS THAT WILL PROGRESSIVELY CARVE OUT UPPER TROF OVER THE NORTHEASTERN PORTION OF THE NATION THIS WEEKEND...DRIVING COOL FRONT INTO AND THROUGH THE BLACKSBURG FORECAST AREA TONIGHT. LOCAL WRF AND HRRR MODELS INDICATING THAT PRECEDING AREA OF SHOWERS MAY HELP GENERATE AND PUSH OUTFLOW BOUNDARY SOUTHEAST OUT AHEAD OF THE FRONT INTO NORTHERN THIRD OF THE BLACKSBURG FORECAST AREA THIS AFTERNOON. DESPITE RATHER LACKLUSTER MID LEVEL INSTABILITY...AND POTENTIAL OF AT LEAST SOME OFFSET OF INSOLATIVE POTENTIAL DUE TO LINGERING MID AND HIGH LEVEL CLOUDS...WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED TO DEVELOP BY/DURING THE EARLY TO MID AFTERNOON IN ASSOCIATED CONFLUENCE ZONE... ESPECIALLY NORTH OF HIGHWAY 460...AND ACROSS WESTERN FLANKS OF THE APPALACHIANS AS WESTERLY UPSLOPING WINDS PROVIDE SOME NEEDED UPWARD ASSIST. MUCH BETTER INSTABILITY REMAINS LOCKED UP OVER SOUTHSIDE VA INTO NORTH CENTRAL NC WHERE MUCH DEEPER LOW LEVEL/TROPICAL MOISTURE RESIDES IN VICINITY OF OLD FRONT. SHORT RANGE AND MESOSCALE MODELS HIGHLIGHT THIS AREA FOR ADDITIONAL SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ALTHOUGH ANY NORTHWARD PUSH OF THIS AIRMASS INTO VA APPEARS UNLIKELY CONSIDERING SLOW VEERING OF WINDS AS ZONAL FLOW INCREASES OVER AREA. IN LIGHT OF THE ABOVE...BEST THREAT FOR WIDELY SCATTERED TO SCATTERED SHOWERS/THUNDERSTORMS TODAY WILL BE ACROSS THE NORTH...NORTHWEST...AND SOUTHEAST PORTION OF THE BLACKSBURG FORECAST AREA...WITH RELATIVE MINIMUM (MORE ISOLATED) THREAT FROM THE FOOTHILLS OF NORTHWEST NC NORTHEAST TOWARD FARMVILLE VA. SEVERE WEATHER THREAT AT THE PRESENT TIME APPEARS TO BE REMOTE. LOSS OF DAYTIME HEATING AND LITTLE TO NO DYNAMIC SUPPORT AS SHORT WAVE ENERGY REMAINS WELL NORTH OF THE BLACKSBURG AREA SHOULD SUPPORT DEMISE OF LINGERING SHOWER/THUNDERSTORM ACTIVITY IN MOST AREAS BEFORE MIDNIGHT TONIGHT...BUT WITH A LOW THREAT OF SOME STRAY SHOWERS REMAINING INTO THE EARLY MORNING HOURS ACROSS THE SOUTHWESTERN MOUNTAINS WHERE A BIT DEEPER MOISTURE PROFILE WILL RESIDE AS COLDER AIR FOLDS INTO AREA FROM THE NORTH. MOS GUIDANCE GENERALLY ACCEPTED FOR THE NEAR TERM PERIOD...WITH HIGHS TODAY IN THE 70S ACROSS THE HIGHER TERRAIN TO 80S ELSEWHERE...WITH OVERNIGHT LOWS MAINLY IN THE 60S EXCLUDING SOME MID TO UPPER 50S IN SOME OF THE DEEPER MOUNTAIN VALLEYS. && .SHORT TERM /SUNDAY THROUGH MONDAY/... AS OF 245 PM EDT FRIDAY... DRIER AIR ARRIVES SUNDAY AFTERNOON ON NW FLOW AND SHOULD SEE INCREASING SUNSHINE. HIGH PRESSURE ARRIVES SUN NIGHT INTO THE CENTRAL APPALACHIANS AND THEN SHIFTS TO THE MID ATLANTIC COAST BY THE END OF THE DAY. NOTICING ENOUGH CONVERGENCE TOWARD MONDAY AFTERNOON TO SQUEEZE OUT SOME SHOWERS IN THE NC MTNS. LOOKS LIKE TEMPS WILL BE WARM SAT NIGHT WITH LOWER 60S MOUNTAINS TO MID TO UPPER 60S EAST. SUNDAY WILL BE MILD/WARM WITH NW WINDS AROUND 10 MPH WITH SHOWERS SHIFTING SOUTH AND DEWPOINTS DROPPING INTO THE 50S. ANTICIPATING HIGHS FROM THE 70S MOUNTAINS TO LOWER TO MID 80S EAST OF THE BLUE RIDGE. SUNDAY NIGHT WILL BE COOLER WITH LOWS IN THE 50S MOUNTAINS AND FOOTHILLS...WITH LOWER 60S SOUTHEAST. MOISTURE WILL START TO INCREASE SOME MONDAY AFTERNOON BUT EXPECT THE DEWPOINTS TO STILL BE IN THE 50S. HIGHS ARE GOING TO RANGE FROM THE MID 70S SOUTHEAST WV/NC MTNS TO AROUND 80 NEW RIVER VALLEY/ROANOKE...AND LOWER 80S FOOTHILLS-PIEDMONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 1205 PM EDT FRIDAY... FORECAST LOOKING SOMEWHAT UNSETTLED AS BROAD TROUGH OVER THE GREAT LAKES AND NORTHEAST SENDS A FRONT OR TWO DOWN MID TO LATE WEEK. FOR MONDAY NIGHT AND TUESDAY...HIGH PRESSURE WILL BE SITUATED ACROSS THE MID ATLANTIC AND PUTTING US IN A E-SE FLOW WITH WEDGING POTENTIAL. MONDAY NIGHT WILL SEE SOME RETURN MOISTURE BANKING UP INTO THE SOUTHERN BLUE RIDGE SO HAVE SLIGHT CHANCE OF SHOWERS THERE. DURING TUESDAY THE FLOW GOES MORE SE-S SO THETA-E RIDGING ACROSS THE BLUE RIDGE AND EAST WHICH WILL HELP IN THE DEVELOPMENT OF SCATTERED SHOWERS AND STORMS...WITH LESS COVERAGE IN WV. WITH A WEAK SFC-8H FLOW GOING FROM SOUTH TO SW AND NW FLOW ALOFT...SOME OF THE STORMS COULD BE SLOW MOVERS LEADING TO HEAVY RAIN. THE MIDDLE OF THE WEEK SHOWS SURFACE HIGH OVER THE WRN ATLANTIC WITH THE SFC FLOW BECOMING OVERALL MORE SW TO WEST. SEVERAL IMPULSES ALONG THE SRN FRINGE OF THE WESTERLIES WILL BE MOVING FROM THE OHIO VALLEY INTO THE MID ATLANTIC AND BRING A BETTER THREAT OF STORMS DURING THE DAY WITH SOME IN THROUGH THE NIGHT. THE UPPER PATTERN BECOMES MORE ZONAL DURING THE WED-FRI TIME FRAME WITH 5H HEIGHTS RISING TO 588 TO 591 DM AND PUTTING US MORE IN TYPICAL SUMMER HUMIDITY. THE NEXT FRONT LOOKS TO ARRIVE ACROSS OUR NECK OF THE WOODS THU-FRI BUT EXPECTING IT TO STALL AS IT BECOMES PARALLEL TO THE FLOW ALOFT. THIS POTENTIALLY COULD BRING OUR FORECAST AREA INTO A PROLONGED PERIOD OF OFF AND ON STORMS. THE SAVING GRACE WILL BE THE FLOW ALOFT WILL BE WESTERLY AND NOT DRAWING AS MUCH MOISTURE FROM THE GULF. FOR TEMPS WILL GO A LITTLE UNDER GUIDANCE EARLY IN THE PIEDMONT WEST TO THE NEW RIVER VALLEY WITH WEDGE LIKE SETUP AND CLOUDS. WILL WARM UP LOWS AND HIGHS BY MIDWEEK BUT EVEN THEN SHOULD BE CLOSE TO NORMAL FOR EARLY AUGUST. CLOUD COVER MAY KEEP HIGHS DOWN SOMEWHAT IF WE GET CONVECTIVE BLOWOFF. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 AM EDT SATURDAY... VFR WEATHER EXPECTED AT ALL TERMINAL FORECAST SITES FOR THE REST OF TONIGHT INTO SATURDAY WITH EXCEPTION OF MOUNTAIN VALLEYS...SUCH AS AT KBCB AND KLWB...AND ACROSS SOUTHSIDE VA AT/NEAR KDAN WHERE PROXIMITY TO OLD FRONTAL BOUNDARY AND MUCH HIGHER DEW POINTS RESIDE...WHERE DEVELOPMENT OF PATCHY LATE NIGHT/EARLY MORNING FOG AND ASSOCIATED LOCALIZED FLIGHT RESTRICTIONS DOWN INTO THE IFR RANGE ARE LIKELY. FOG SHOULD RAPIDLY LIFT/MIX OUT BY 13Z/900 AM WITH ONSET OF DAYTIME HEATING. EARLY MORNING CONVECTION DEVELOPING OVER CENTRAL NC AS MOIST AIR TRIES TO MAKE A PUSH BACK TOWARD THE NORTH MAY MAKE AN ATTEMPT TO THREATEN KDAN TOWARD DAYBREAK...BUT CURRENT THINKING IS THAT ACTUAL FLIGHT IMPACT FROM TSRA WILL REMAIN SOUTH OF THE STATE LINE...BUT CLOSE ENOUGH TO WARRANT MORNING INCLUSION OF VCTS AT KDAN. APPROACH OF NEXT FRONTAL SYSTEM TO THE NORTH AND WEST...AND WEAK QUASI-STATIONARY WARM/MOIST BOUNDARY JUST TO THE SOUTH...COUPLED WITH INCREASING INSOLATION SHOULD BE SUFFICIENT TO SUPPORT THE DEVELOPMENT OF WIDELY SCATTERED SHOWERS/STORMS IN JUST ABOUT ALL AREAS THIS AFTERNOON INTO THIS EVENING...WITH ACTIVITY MAXIMIZED NORTH OF HIGHWAY 460...ACROSS THE WESTERN FLANKS OF THE APPALACHIANS...AND OUT ACROSS THE PIEDMONT MAINLY ALONG AND SOUTH OF THE VA/NC STATE LINE. ACTUAL THREAT OF TSRA AT ANY TERMINAL FORECAST POINT REMAINS TOO LOW TO WARRANT ANYTHING OTHER THAN VCTS INCLUSION AT THE PRESENT TIME...BUT WILL AMEND AS NECESSARY IF ANY PARTICULAR STORM THREATENS ANY OF THE AIRPORTS LATER TODAY. ONSET OF NIGHTTIME COOLING AND PASSAGE COOL FRONT SHOULD END THREAT OF SHOWERS/STORMS THIS EVENING IN MOST AREAS...WITH VFR WEATHER THEN EXPECTED TO PREDOMINATE SUNDAY INTO MONDAY (OTHER THAN TYPICAL LATE NIGHT/EARLY MORNING PATCHY FOG IN MOUNTAIN VALLEYS AND LOW LYING SHELTERED AREAS OF THE PIEDMONT) AS HIGH PRESSURE SETTLES INTO/OVER THE AREA. AFTERNOON CONVECTION EXPECTED TO RETURN TO THE AREA BY TUESDAY AFTERNOON AS SURFACE RIDGE MOVES OFF TO THE EAST AND AS SOUTHERLY WINDS RETURN TO THE REGION...BRINGING AN INCREASE OF LOW LEVEL MOISTURE. WEDNESDAY OFFERS THE HIGHEST THREAT FOR A MORE ORGANIZED SHRA/TSRA EVENT ALONG WITH ATTENDANT LOWER CIGS/VSBYS AS TROPICAL MOISTURE RETURNS TO THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WERT NEAR TERM...WERT SHORT TERM...WP LONG TERM...WP AVIATION...CF/KK/WERT
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
1038 PM PDT Fri Aug 2 2013 .SYNOPSIS... Unsettled weather will continue this evening with rain showers and a few thunderstorms. Lingering showers will be common near the Canadian border through Saturday. Summer weather will return next week with a warm up back to normal and small chances of mainly mountain thunderstorms each day. && .DISCUSSION... Update this evening was to increase chance of rain overnight across the basin. HRRR has been consistent the last several runs of keeping rain going across the basin through the night. It also has shown very little precip across extreme northeast WA and north ID as well as Lewiston and areas southeast towards the Camas Prairie overnight. So adjusted accordingly and lowered chance of precip. Cannot discount an isolated shower anywhere given the proximity of the low. Low temps look to be on track, about 2-5 degrees below average for this time of the year. It was quite a chilly day today. Looks like we start to rebound tomorrow, although we will still be about 10 degrees below average. Nisbet && .AVIATION... 06Z TAFS...VFR expected at all TAF sites. -RA will continue from the Spokane area south and west towards the Tri Cities through the overnight hours. Given the recent rains, patchy fog is possible at TAF sites, and anywhere that received decent amts of rain, but wasn`t confident enough to add it to the TAFs. Showers will once again form across the northern mtns near 17z Sat. && .PRELIMINARY POINT TEMPS/POPS... Spokane 55 74 57 84 61 87 / 40 30 10 10 10 10 Coeur d`Alene 53 74 53 83 55 85 / 30 40 10 10 10 10 Pullman 50 74 49 83 50 87 / 20 20 10 10 10 10 Lewiston 56 82 59 92 62 94 / 10 10 10 10 10 10 Colville 52 78 52 87 52 87 / 20 40 20 20 10 10 Sandpoint 51 71 47 81 49 82 / 30 60 30 10 10 20 Kellogg 50 74 51 82 54 84 / 40 40 10 10 10 10 Moses Lake 59 81 58 89 61 92 / 60 10 10 10 0 10 Wenatchee 61 81 61 90 65 92 / 50 20 10 10 0 10 Omak 60 84 57 89 59 92 / 50 30 20 20 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
447 PM MDT SAT AUG 3 2013 .UPDATE... ISSUED AT 344 PM MDT SAT AUG 3 2013 LONG TRACKED SEVERE THUNDERSTORM CONTINUES TO HOLD TOGETHER AND MOVE NORTH INTO NORTHERN LARAMIE COUNTY. WENT AHEAD AND ADDED PLATTE AND GOSHEN COUNTIES TO THE TORNADO WATCH AS THIS STORM COULD PRODUCE SEVERE THUNDERSTORMS THERE. PLUS THE ENVIRONMENT IS PROBABLY BETTER UP THERE FOR MORE WIDESPREAD THUNDERSTORM DEVELOPMENT. UPDATES HAVE BEEN SENT. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 300 PM MDT SAT AUG 3 2013 FORECAST CHALLENGES DEAL WITH THUNDERSTORM TIMING AND LOCATION OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH EVENING HOURS. CURRENTLY...BOUNDARY LAYING ALONG THE LARAMIE RANGE EARLY THIS AFTERNOON...SEPARATING FAIRLY DRY AIR TO THE WEST FROM REALLY MOIST AIR TO THE EAST. DEWPOINTS IN LARAMIE IN THE MID 30S...HERE AT CHEYENNE WE ARE SEEING UPPER 50S AND OUT BY SIDNEY...MID 60 DEWPOINTS. STRATUS HAS BEEN SLOW TO BREAK UP LATE THIS MORNING/EARLY THIS AFTERNOON. STILL GETTING REPORTS OF STRATUS IN THE PANHANDLE AND AS FAR WEST AS TORRINGTON. CHEYENNE HAS REMAINED UNDER MOSTLY SUNNY SKIES AND CUMULUS HAS BEGUN TO BUILD OVER THE SOUTHERN LARAMIE RANGE...EXTENDING SOUTH INTO THE MOUNTAINS OF COLORADO. GETTING OBSERVED LIGHTNING STRIKES OVER CENTRAL COLORADO...BUT SO FAR...THE CHEYENNE CWFA HAS REMAINED PRETTY MUCH ECHO FREE. MONSOONAL MOISTURE CONTINUES TO MOVE INTO SOUTH CENTRAL WYOMING ON WATER VAPOR IMAGERY...MAINLY OVER SOUTHERN CARBON AND ALBANY COUNTIES THROUGH THE MORNING HOURS. DO BELIEVE ITS ONLY A MATTER OF TIME FOR CONVECTION TO INITIATE THIS AFTERNOON. LATEST SPC MESOANALIST PAGE SHOWING SURFACE BASED CAPE VALUES INCREASING TO AROUND 3500 J/KG JUST SOUTH OF THE CWFA IN COLORADO WITH AROUND 2500 TO 3000 J/KG JUST NUDGING INTO THE SOUTH LARAMIE RANGE. STILL SEEING SOME CONVECTIVE INHIBITION EAST OF CHEYENNE...SPREADING NORTH AND EAST. SPC MESOANALYST PAGE SHOWING STILL AROUND 100-150 J/KG CONVECTIVE INHIBITION FOR THESE AREAS. CURRENTLY THINKING AND THIS IS BACKED UP BY LATEST HRRR FORECASTS IS THAT CONVECTION WILL INITIATE JUST WEST OF CHEYENNE...THEN SLOWLY SPREAD EAST AND NORTH AS THE CAP ERODES. MAIN THREATS WITH THUNDERSTORMS TODAY LOOKS TO BE LARGE HAIL AND DAMAGING WINDS. BULK SHEAR ON THE ORDER OF 40 TO 45KTS. BUT LATER THIS AFTERNOON...NAM SOUNDINGS ARE SHOWING HELICITY VALUES INCREASING ABOVE 200 M2/S2 FOR CHEYENNE AND THE SOUTHERN PANHANDLE...SO CAN NOT RULE OUT SOME TORNADIC SUPERCELLS LATE THIS AFTERNOON AND EARLY EVENING. LCLS PRETTY LOW...WITH NAM FORECASTING ANYWHERE FROM 2K TO 3K AGL. FINALLY...HEAVY RAIN IS A CONCERN WITH PWATS CLIMBING TO OVER 1 INCH HERE AT CHEYENNE AND 1.4 INCHES OUT BY SIDNEY. STORM MOTIONS ARE FAIRLY SLOW...GENERALLY OUT OF THE WEST AT LESS THAN 10KTS...SO WE COULD BE LOOKING AT A FLASH FLOOD THREAT AS WELL IN AREAS THAT SEE TRAINING STORMS. STORMS SHOULD CONTINUE INTO THE MID TO LATE EVENING HOURS...SPREADING INTO THE PANHANDLE BY 6 PM OR SO TONIGHT. FOR SUNDAY...MODELS INDICATING A REPEAT OF TODAYS WEATHER WITH POSSIBLY CONVECTION FURTHER EAST INTO THE PANHANDLE INITIALLY. SEVERE THUNDERSTORMS LOOK MORE OUT OVER THE PANHANDLE SUNDAY VS INITIATING HERE IN SOUTHEAST WYOMING. .LONG TERM...(TUESDAY THROUGH SATURDAY) ISSUED AT 320 PM MDT SAT AUG 3 2013 MAIN FORECAST CONCERN THROUGH NEXT WEEK WILL BE A STRONG MID SUMMER COLD FRONT PUSHING ACROSS THE GREAT PLAINS AND INTO THE FORECAST AREA...AS THE DEEP 543DM UPPER LEVEL LOW SETTLES OVER SOUTHERN CANADA NEAR THE GREAT LAKES REGION. THIS IS PRETTY UNUSUAL FOR THIS TIME OF THE YEAR...ALTHOUGH THE ROCKY MOUNTAIN REGION WILL NOT SEE THE MAJORITY OF THIS COOLER AIR. MODELS SHOW THIS FRONT QUICKLY MOVING ACROSS THE AREA TUESDAY AND TUESDAY EVENING WITH HIGH TEMPERATURES AROUND 10 TO 15 DEGREES COOLER ON WEDNESDAY AND THURSDAY. WITH SUBTROPICAL MONSOON MOISTURE IN PLACE...A DAILY CHANCE OF SHOWERS AND THUNDERSTORMS IS ANTICIPATED ACROSS MOST OF THE FORECAST AREA. THE BEST CHANCE WILL REMAIN OVER THE MOUNTAINS AND ALONG/EAST OF THE LARAMIE RANGE...PRIMARILY FROM MID AFTERNOON THROUGH EARLY IN THE EVENING. SOME OF THESE SHOWERS MAY CONTINUE INTO THE OVERNIGHT HOURS...ESPECIALLY WEDNESDAY AND THURSDAY NIGHT. && .AVIATION...(FOR THE 00Z TAF ISSUANCE) SHOWERS AND TSTORMS WILL CONTINUE OVER SOUTHEAST WYOMING. LOW CONFIDENCE IN TSTORMS ACROSS WESTERN NEBRASKA DUE TO ONGOING FOG AND LOW CIGS...SO TOOK VCTS OUT OF MOST WESTERN NEBRASKA TERMINALS OR STARTED VCTS LATER THIS EVENING. STORMS THAT OCCUR NEAR THE WY/NE BORDER ARE CAPABLE OF PRODUCING LARGE HAIL AS WELL. TSTORMS WILL DISSIPATE LATE TONIGHT...BUT WITH MOIST SOUTHERLY FLOW REMAINING OVER THE AREA EXPECT PATCHY FOG AND LOW CIGS BELOW 1K FEET AGL TO CONTINUE ACROSS THE HIGH PLAINS INTO WESTERN NEBRASKA THROUGH TONIGHT. && .FIRE WEATHER... ISSUED AT 300 PM MDT SAT AUG 3 2013 LIGHT WINDS AND MONSOONAL MOISTURE SHOULD KEEP FIRE WEATHER ISSUES AT BAY FOR TODAY AND SUNDAY. AREAS EAST OF THE LARAMIE RANGE SHOULD SEE CONTINUED GOOD CHANCES AT WETTING RAINS...HIGH HUMIDITIES AND EASTERLY UPSLOPING WINDS. AREAS WEST WILL SEE DRIER CONDITIONS WITH AFTERNOON HUMIDITIES FALLING INTO MID TEENS. FORTUNATELY...WINDS SHOULD STAY LIGHT OUT THAT WAY KEEPING FIRE WEATHER CONCERNS MINIMAL. BY MONDAY...SURFACE HIGH PRESSURE MOVING INTO NORTH CENTRAL COLORADO WILL RE-ESTABLISH WESTERLY WINDS WITH DRIER AIR FILTERING IN TO AREAS EAST OF THE LARAMIE RANGE. WINDS WILL REMAIN LIGHT THOUGH...WHICH WILL KEEP FIRE WEATHER MINIMIZED. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...CLAYCOMB SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...TJT FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
347 PM MDT SAT AUG 3 2013 .UPDATE... ISSUED AT 344 PM MDT SAT AUG 3 2013 LONG TRACKED SEVERE THUNDERSTORM CONTINUES TO HOLD TOGETHER AND MOVE NORTH INTO NORTHERN LARAMIE COUNTY. WENT AHEAD AND ADDED PLATTE AND GOSHEN COUNTIES TO THE TORNADO WATCH AS THIS STORM COULD PRODUCE SEVERE THUNDERSTORMS THERE. PLUS THE ENVIRONMENT IS PROBABLY BETTER UP THERE FOR MORE WIDESPREAD THUNDERSTORM DEVELOPMENT. UPDATES HAVE BEEN SENT. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 300 PM MDT SAT AUG 3 2013 FORECAST CHALLENGES DEAL WITH THUNDERSTORM TIMING AND LOCATION OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH EVENING HOURS. CURRENTLY...BOUNDARY LAYING ALONG THE LARAMIE RANGE EARLY THIS AFTERNOON...SEPARATING FAIRLY DRY AIR TO THE WEST FROM REALLY MOIST AIR TO THE EAST. DEWPOINTS IN LARAMIE IN THE MID 30S...HERE AT CHEYENNE WE ARE SEEING UPPER 50S AND OUT BY SIDNEY...MID 60 DEWPOINTS. STRATUS HAS BEEN SLOW TO BREAK UP LATE THIS MORNING/EARLY THIS AFTERNOON. STILL GETTING REPORTS OF STRATUS IN THE PANHANDLE AND AS FAR WEST AS TORRINGTON. CHEYENNE HAS REMAINED UNDER MOSTLY SUNNY SKIES AND CUMULUS HAS BEGUN TO BUILD OVER THE SOUTHERN LARAMIE RANGE...EXTENDING SOUTH INTO THE MOUNTAINS OF COLORADO. GETTING OBSERVED LIGHTNING STRIKES OVER CENTRAL COLORADO...BUT SO FAR...THE CHEYENNE CWFA HAS REMAINED PRETTY MUCH ECHO FREE. MONSOONAL MOISTURE CONTINUES TO MOVE INTO SOUTH CENTRAL WYOMING ON WATER VAPOR IMAGERY...MAINLY OVER SOUTHERN CARBON AND ALBANY COUNTIES THROUGH THE MORNING HOURS. DO BELIEVE ITS ONLY A MATTER OF TIME FOR CONVECTION TO INITIATE THIS AFTERNOON. LATEST SPC MESOANALIST PAGE SHOWING SURFACE BASED CAPE VALUES INCREASING TO AROUND 3500 J/KG JUST SOUTH OF THE CWFA IN COLORADO WITH AROUND 2500 TO 3000 J/KG JUST NUDGING INTO THE SOUTH LARAMIE RANGE. STILL SEEING SOME CONVECTIVE INHIBITION EAST OF CHEYENNE...SPREADING NORTH AND EAST. SPC MESOANALYST PAGE SHOWING STILL AROUND 100-150 J/KG CONVECTIVE INHIBITION FOR THESE AREAS. CURRENTLY THINKING AND THIS IS BACKED UP BY LATEST HRRR FORECASTS IS THAT CONVECTION WILL INITIATE JUST WEST OF CHEYENNE...THEN SLOWLY SPREAD EAST AND NORTH AS THE CAP ERODES. MAIN THREATS WITH THUNDERSTORMS TODAY LOOKS TO BE LARGE HAIL AND DAMAGING WINDS. BULK SHEAR ON THE ORDER OF 40 TO 45KTS. BUT LATER THIS AFTERNOON...NAM SOUNDINGS ARE SHOWING HELICITY VALUES INCREASING ABOVE 200 M2/S2 FOR CHEYENNE AND THE SOUTHERN PANHANDLE...SO CAN NOT RULE OUT SOME TORNADIC SUPERCELLS LATE THIS AFTERNOON AND EARLY EVENING. LCLS PRETTY LOW...WITH NAM FORECASTING ANYWHERE FROM 2K TO 3K AGL. FINALLY...HEAVY RAIN IS A CONCERN WITH PWATS CLIMBING TO OVER 1 INCH HERE AT CHEYENNE AND 1.4 INCHES OUT BY SIDNEY. STORM MOTIONS ARE FAIRLY SLOW...GENERALLY OUT OF THE WEST AT LESS THAN 10KTS...SO WE COULD BE LOOKING AT A FLASH FLOOD THREAT AS WELL IN AREAS THAT SEE TRAINING STORMS. STORMS SHOULD CONTINUE INTO THE MID TO LATE EVENING HOURS...SPREADING INTO THE PANHANDLE BY 6 PM OR SO TONIGHT. FOR SUNDAY...MODELS INDICATING A REPEAT OF TODAYS WEATHER WITH POSSIBLY CONVECTION FURTHER EAST INTO THE PANHANDLE INITIALLY. SEVERE THUNDERSTORMS LOOK MORE OUT OVER THE PANHANDLE SUNDAY VS INITIATING HERE IN SOUTHEAST WYOMING. .LONG TERM...(TUESDAY THROUGH SATURDAY) ISSUED AT 320 PM MDT SAT AUG 3 2013 MAIN FORECAST CONCERN THROUGH NEXT WEEK WILL BE A STRONG MID SUMMER COLD FRONT PUSHING ACROSS THE GREAT PLAINS AND INTO THE FORECAST AREA...AS THE DEEP 543DM UPPER LEVEL LOW SETTLES OVER SOUTHERN CANADA NEAR THE GREAT LAKES REGION. THIS IS PRETTY UNUSUAL FOR THIS TIME OF THE YEAR...ALTHOUGH THE ROCKY MOUNTAIN REGION WILL NOT SEE THE MAJORITY OF THIS COOLER AIR. MODELS SHOW THIS FRONT QUICKLY MOVING ACROSS THE AREA TUESDAY AND TUESDAY EVENING WITH HIGH TEMPERATURES AROUND 10 TO 15 DEGREES COOLER ON WEDNESDAY AND THURSDAY. WITH SUBTROPICAL MONSOON MOISTURE IN PLACE...A DAILY CHANCE OF SHOWERS AND THUNDERSTORMS IS ANTICIPATED ACROSS MOST OF THE FORECAST AREA. THE BEST CHANCE WILL REMAIN OVER THE MOUNTAINS AND ALONG/EAST OF THE LARAMIE RANGE...PRIMARILY FROM MID AFTERNOON THROUGH EARLY IN THE EVENING. SOME OF THESE SHOWERS MAY CONTINUE INTO THE OVERNIGHT HOURS...ESPECIALLY WEDNESDAY AND THURSDAY NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING) ISSUED AT 1144 AM MDT SAT AUG 3 2013 IFR TO LIFR CEILINGS AND VISIBILITIES WILL CONTINUE ACROSS EASTERN PORTIONS OF THE FORECAST AREA EARLY THIS AFTERNOON AS EAST TO SOUTHEAST UPSLOPE FLOW COMBINES WITH A VERY MOISTURE BOUNDARY LAYER. CONDITIONS WILL BE SLOW TO IMPROVE WITH SOME AREAS SUCH AS KSNY LIKELY NOT FULLY BREAK OUT OF MVFR CONDITIONS TODAY. SHOWERS AND THUNDERSTORMS WILL REDEVELOP OVER THE MOUNTAINS IN THE NEXT HOUR OR TWO...AND WILL MOVE EAST ACROSS THE PLAINS THROUGH THE AFTERNOON AND EVENING. EXPECTING IFR TO MVFR CONDITIONS IN BRIEF HEAVY RAIN ALONG WITH GUSTY AND ERRATIC DOWNDRAFT WINDS. STORMS THAT OCCUR NEAR THE WY/NE BORDER AND SITES TO THE EAST ARE CAPABLE OF PRODUCING LARGE HAIL AS WELL. WITH LOW CIGS AND PATCHY FOG LINGERING OVER PORTIONS OF WESTERN NEBRASKA...THERE IS A LOT OF UNCERTAINTY AS TO WHEN TSTORMS WILL MOVE OVER THOSE AREAS DUE TO A STABLE LOW BOUNDARY LAYER. KEPT VCTS IN THOSE LOCATIONS DUE TO THE LACK OF CONFIDENCE ABOUT TSTORM TIMING LATE THIS AFTERNOON AND INTO THIS EVENING. TSTORMS WILL DISSIPATE LATE TONIGHT...BUT WITH MOIST SOUTHERLY FLOW A RETURN TO IFR/LIFR CONDITIONS TO EASTERN TERMINALS IS EXPECTED AGAIN TONIGHT IN LOW CLOUDS AND FOG. && .FIRE WEATHER... ISSUED AT 300 PM MDT SAT AUG 3 2013 LIGHT WINDS AND MONSOONAL MOISTURE SHOULD KEEP FIRE WEATHER ISSUES AT BAY FOR TODAY AND SUNDAY. AREAS EAST OF THE LARAMIE RANGE SHOULD SEE CONTINUED GOOD CHANCES AT WETTING RAINS...HIGH HUMIDITIES AND EASTERLY UPSLOPING WINDS. AREAS WEST WILL SEE DRIER CONDITIONS WITH AFTERNOON HUMIDITIES FALLING INTO MID TEENS. FORTUNATELY...WINDS SHOULD STAY LIGHT OUT THAT WAY KEEPING FIRE WEATHER CONCERNS MINIMAL. BY MONDAY...SURFACE HIGH PRESSURE MOVING INTO NORTH CENTRAL COLORADO WILL RE-ESTABLISH WESTERLY WINDS WITH DRIER AIR FILTERING IN TO AREAS EAST OF THE LARAMIE RANGE. WINDS WILL REMAIN LIGHT THOUGH...WHICH WILL KEEP FIRE WEATHER MINIMIZED. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...CLAYCOMB SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...TJT FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
320 PM MDT SAT AUG 3 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 300 PM MDT SAT AUG 3 2013 FORECAST CHALLENGES DEAL WITH THUNDERSTORM TIMING AND LOCATION OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH EVENING HOURS. CURRENTLY...BOUNDARY LAYING ALONG THE LARAMIE RANGE EARLY THIS AFTERNOON...SEPARATING FAIRLY DRY AIR TO THE WEST FROM REALLY MOIST AIR TO THE EAST. DEWPOINTS IN LARAMIE IN THE MID 30S...HERE AT CHEYENNE WE ARE SEEING UPPER 50S AND OUT BY SIDNEY...MID 60 DEWPOINTS. STRATUS HAS BEEN SLOW TO BREAK UP LATE THIS MORNING/EARLY THIS AFTERNOON. STILL GETTING REPORTS OF STRATUS IN THE PANHANDLE AND AS FAR WEST AS TORRINGTON. CHEYENNE HAS REMAINED UNDER MOSTLY SUNNY SKIES AND CUMULUS HAS BEGUN TO BUILD OVER THE SOUTHERN LARAMIE RANGE...EXTENDING SOUTH INTO THE MOUNTAINS OF COLORADO. GETTING OBSERVED LIGHTNING STRIKES OVER CENTRAL COLORADO...BUT SO FAR...THE CHEYENNE CWFA HAS REMAINED PRETTY MUCH ECHO FREE. MONSOONAL MOISTURE CONTINUES TO MOVE INTO SOUTH CENTRAL WYOMING ON WATER VAPOR IMAGERY...MAINLY OVER SOUTHERN CARBON AND ALBANY COUNTIES THROUGH THE MORNING HOURS. DO BELIEVE ITS ONLY A MATTER OF TIME FOR CONVECTION TO INITIATE THIS AFTERNOON. LATEST SPC MESOANALIST PAGE SHOWING SURFACE BASED CAPE VALUES INCREASING TO AROUND 3500 J/KG JUST SOUTH OF THE CWFA IN COLORADO WITH AROUND 2500 TO 3000 J/KG JUST NUDGING INTO THE SOUTH LARAMIE RANGE. STILL SEEING SOME CONVECTIVE INHIBITION EAST OF CHEYENNE...SPREADING NORTH AND EAST. SPC MESOANALYST PAGE SHOWING STILL AROUND 100-150 J/KG CONVECTIVE INHIBITION FOR THESE AREAS. CURRENTLY THINKING AND THIS IS BACKED UP BY LATEST HRRR FORECASTS IS THAT CONVECTION WILL INITIATE JUST WEST OF CHEYENNE...THEN SLOWLY SPREAD EAST AND NORTH AS THE CAP ERODES. MAIN THREATS WITH THUNDERSTORMS TODAY LOOKS TO BE LARGE HAIL AND DAMAGING WINDS. BULK SHEAR ON THE ORDER OF 40 TO 45KTS. BUT LATER THIS AFTERNOON...NAM SOUNDINGS ARE SHOWING HELICITY VALUES INCREASING ABOVE 200 M2/S2 FOR CHEYENNE AND THE SOUTHERN PANHANDLE...SO CAN NOT RULE OUT SOME TORNADIC SUPERCELLS LATE THIS AFTERNOON AND EARLY EVENING. LCLS PRETTY LOW...WITH NAM FORECASTING ANYWHERE FROM 2K TO 3K AGL. FINALLY...HEAVY RAIN IS A CONCERN WITH PWATS CLIMBING TO OVER 1 INCH HERE AT CHEYENNE AND 1.4 INCHES OUT BY SIDNEY. STORM MOTIONS ARE FAIRLY SLOW...GENERALLY OUT OF THE WEST AT LESS THAN 10KTS...SO WE COULD BE LOOKING AT A FLASH FLOOD THREAT AS WELL IN AREAS THAT SEE TRAINING STORMS. STORMS SHOULD CONTINUE INTO THE MID TO LATE EVENING HOURS...SPREADING INTO THE PANHANDLE BY 6 PM OR SO TONIGHT. FOR SUNDAY...MODELS INDICATING A REPEAT OF TODAYS WEATHER WITH POSSIBLY CONVECTION FURTHER EAST INTO THE PANHANDLE INITIALLY. SEVERE THUNDERSTORMS LOOK MORE OUT OVER THE PANHANDLE SUNDAY VS INITIATING HERE IN SOUTHEAST WYOMING. .LONG TERM...(TUESDAY THROUGH SATURDAY) ISSUED AT 320 PM MDT SAT AUG 3 2013 MAIN FORECAST CONCERN THROUGH NEXT WEEK WILL BE A STRONG MID SUMMER COLD FRONT PUSHING ACROSS THE GREAT PLAINS AND INTO THE FORECAST AREA...AS THE DEEP 543DM UPPER LEVEL LOW SETTLES OVER SOUTHERN CANADA NEAR THE GREAT LAKES REGION. THIS IS PRETTY UNUSUAL FOR THIS TIME OF THE YEAR...ALTHOUGH THE ROCKY MOUNTAIN REGION WILL NOT SEE THE MAJORITY OF THIS COOLER AIR. MODELS SHOW THIS FRONT QUICKLY MOVING ACROSS THE AREA TUESDAY AND TUESDAY EVENING WITH HIGH TEMPERATURES AROUND 10 TO 15 DEGREES COOLER ON WEDNESDAY AND THURSDAY. WITH SUBTROPICAL MONSOON MOISTURE IN PLACE...A DAILY CHANCE OF SHOWERS AND THUNDERSTORMS IS ANTICIPATED ACROSS MOST OF THE FORECAST AREA. THE BEST CHANCE WILL REMAIN OVER THE MOUNTAINS AND ALONG/EAST OF THE LARAMIE RANGE...PRIMARILY FROM MID AFTERNOON THROUGH EARLY IN THE EVENING. SOME OF THESE SHOWERS MAY CONTINUE INTO THE OVERNIGHT HOURS...ESPECIALLY WEDNESDAY AND THURSDAY NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING) ISSUED AT 1144 AM MDT SAT AUG 3 2013 IFR TO LIFR CEILINGS AND VISIBILITIES WILL CONTINUE ACROSS EASTERN PORTIONS OF THE FORECAST AREA EARLY THIS AFTERNOON AS EAST TO SOUTHEAST UPSLOPE FLOW COMBINES WITH A VERY MOISTURE BOUNDARY LAYER. CONDITIONS WILL BE SLOW TO IMPROVE WITH SOME AREAS SUCH AS KSNY LIKELY NOT FULLY BREAK OUT OF MVFR CONDITIONS TODAY. SHOWERS AND THUNDERSTORMS WILL REDEVELOP OVER THE MOUNTAINS IN THE NEXT HOUR OR TWO...AND WILL MOVE EAST ACROSS THE PLAINS THROUGH THE AFTERNOON AND EVENING. EXPECTING IFR TO MVFR CONDITIONS IN BRIEF HEAVY RAIN ALONG WITH GUSTY AND ERRATIC DOWNDRAFT WINDS. STORMS THAT OCCUR NEAR THE WY/NE BORDER AND SITES TO THE EAST ARE CAPABLE OF PRODUCING LARGE HAIL AS WELL. WITH LOW CIGS AND PATCHY FOG LINGERING OVER PORTIONS OF WESTERN NEBRASKA...THERE IS A LOT OF UNCERTAINTY AS TO WHEN TSTORMS WILL MOVE OVER THOSE AREAS DUE TO A STABLE LOW BOUNDARY LAYER. KEPT VCTS IN THOSE LOCATIONS DUE TO THE LACK OF CONFIDENCE ABOUT TSTORM TIMING LATE THIS AFTERNOON AND INTO THIS EVENING. TSTORMS WILL DISSIPATE LATE TONIGHT...BUT WITH MOIST SOUTHERLY FLOW A RETURN TO IFR/LIFR CONDITIONS TO EASTERN TERMINALS IS EXPECTED AGAIN TONIGHT IN LOW CLOUDS AND FOG. && .FIRE WEATHER... ISSUED AT 300 PM MDT SAT AUG 3 2013 LIGHT WINDS AND MONSOONAL MOISTURE SHOULD KEEP FIRE WEATHER ISSUES AT BAY FOR TODAY AND SUNDAY. AREAS EAST OF THE LARAMIE RANGE SHOULD SEE CONTINUED GOOD CHANCES AT WETTING RAINS...HIGH HUMIDITIES AND EASTERLY UPSLOPING WINDS. AREAS WEST WILL SEE DRIER CONDITIONS WITH AFTERNOON HUMIDITIES FALLING INTO MID TEENS. FORTUNATELY...WINDS SHOULD STAY LIGHT OUT THAT WAY KEEPING FIRE WEATHER CONCERNS MINIMAL. BY MONDAY...SURFACE HIGH PRESSURE MOVING INTO NORTH CENTRAL COLORADO WILL RE-ESTABLISH WESTERLY WINDS WITH DRIER AIR FILTERING IN TO AREAS EAST OF THE LARAMIE RANGE. WINDS WILL REMAIN LIGHT THOUGH...WHICH WILL KEEP FIRE WEATHER MINIMIZED. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...TJT FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
334 AM CDT MON AUG 5 2013 .DISCUSSION... DIFFERENT DAY...SAME FORECAST. MAIN CONCERNS REMAIN CHANCES OF CONVECTION WITH THUNDERSTORM COMPLEXES MOVING ACROSS AR...MAINLY TODAY AND TUESDAY...WITH POSSIBLE HEAVY RAIN THREAT AND FLASH FLOODING POTENTIAL. TEMPERATURE FORECAST WILL BE LOWER THAN NORMAL OVER NORTHERN AR...WHILE AROUND NORMAL TO A BIT ABOVE SOUTHERN AREAS. LOWER RAIN CHANCES EXPECTED WEDNESDAY AND THURSDAY. MAIN CONVECTION TONIGHT HAS BEEN FOCUSED OVER EASTERN KS TO MO...WITH LIGHT CONVECTION OVER EASTERN OK TO NORTHERN AR. TONIGHT HAVE SEEN THE MCV AHEAD OF LAST NIGHT...AND CONVECTION HAS MADE IT TO NORTHERN AR. ALSO DID SEE CONVECTION HELPED WITH THE WEAK WARM FRONT OVER SOUTHERN AR. THIS MORNING IT REMAINS OVER OVER SOUTHERN AR WHERE SOUTH OF THE BOUNDARY DEW POINT TEMPS WERE IN THE MID 70S...WHILE MAINLY LOWER 70S THE REST OF AR. 00Z SOUNDING AT KLZK AND KSGF CONTINUED THE PRECIP WATER VALUE AROUND 2 INCHES AND UNSTABLE. A LOW LEVEL JET WAS EVIDENT INTO EASTERN KS TO EASTERN OK...THEN INTO SW MO. THE UPPER NW PATTERN CONTINUES INTO THE REGION...WITH THE LATEST SHORT WAVE MOVING OVER THE OZARKS OF OK...MO TO AR. ADDITIONAL ENERGY WAS SEEN UPSTREAM WHICH WILL AFFECT THE REGION MONDAY NIGHT. RAINS OVER NORTHERN AR WERE LOWER THAN PREVIOUS DAY BUT OVERALL VALUES OVER THE LAST SEVERAL DAYS ARE 1 TO 3 INCHES. SO FLASH FLOOD WATCH WILL BE IN AFFECT THROUGH MONDAY NIGHT...WITH THE POTENTIAL FOR FLASH FLOODING WITH HEAVY RAIN. && .SHORT TERM...TODAY THROUGH THURSDAY NIGHT TODAY`S FORECAST WILL START WITH A HIGH POP OVER NORTHERN AR DUE TO ON GOING CONVECTION. THE FLASH WATCH WILL CONTINUE THROUGH AT LEAST TONIGHT WITH MODELS SHOWING ANOTHER MCV EXPECTED TO AFFECT PARTS OF NORTHERN AR. WRF AND HRRR MODELS ARE A BIT DIFFERENT IN THEIR SOLUTIONS EARLY TODAY...AND LIKE HRRR BASED ON ON GOING TRENDS. MAIN SURGE OF CONVECTION WILL CONTINUE OVER NORTHERN TO PARTS OF NORTHERN CENTRAL AR TODAY...WITH A E TO SE MOVEMENT AS IT MOVES FROM KS AND MO...THEN INTO AR. PRECIP WATER VALUES REMAIN AROUND 2 INCHES OR MORE...AND STORMS WILL PRODUCE HEAVY RAIN. FLASH FLOOD WATCH THOSE AREAS THAT HAVE RECEIVED RAIN OVER THE LAST FEW DAYS AND WHERE TODAY`S HEAVY RAIN BAND WILL BE. LATER TODAY THE MCV MOVES EAST OF AR...THEN TONIGHT THE UPPER RIDGE IS FORECAST TO BUILD A BIT MORE EAST...AND TAKE THE NEXT COMPLEX MORE NORTH TO EAST...WHICH WILL AFFECT MORE N TO NE AR. THIS HOLDS INTO TUESDAY WITH FORECAST POP MORE OVER N TO NE AR. STILL SOME CHANCE WILL BE OVER MUCH OF THE STATE...BUT SHOULD BE LOWER. TUESDAY NIGHT TO WEDNESDAY AND THURSDAY...CONVECTION IS ALSO EXPECTED TO BE MORE FOCUSED OVER NORTHERN AR WITH MODEL FORECAST SHORT WAVE ENERGY. A FLASH FLOOD WATCH WILL PROBABLY BE DROP LATER TUESDAY TO WEDNESDAY BUT MAY HAVE TO BE CONSIDERED IF MORE HEAVY CONVECTION IS ANTICIPATED. OTHERWISE TEMPERATURES WILL GRADUALLY WARM INTO MID WEEK AS THE UPPER RIDGE LOWERS RAIN CHANCES A BIT AND THE HEAT OVER TEXAS MOVES INTO AR. && .LONG TERM...FRIDAY THROUGH SUNDAY UPPER LEVEL HIGH PRESSURE WILL BE OVER ARKANSAS THROUGH THE LONG TERM PERIOD. ALSO...THE HIGH WILL STRENGTHEN NORTHWEST INTO THE NORTHERN ROCKIES. A COLD FRONT WILL MOVE INTO NORTH ARKANSAS FRIDAY AND STALL. THE FRONT SHOULD HANG AROUND NORTH ARKANSAS THROUGH THE WEEKEND. THIS WILL KEEP CHANCES OF SHOWERS AND THUNDERSTORMS IN THE FORECAST WITH BEST CHANCES IN THE NORTH THROUGH THE PERIOD. THE HIGH PRESSURE MAY SHIFT WESTWARD SUNDAY AND PROVIDE MORE OF A NORTHWEST FLOW AND BETTER CHANCES OF PRECIPITATION. NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 86 72 91 73 / 80 30 30 20 CAMDEN AR 94 76 97 75 / 50 10 10 10 HARRISON AR 88 72 91 72 / 90 30 20 20 HOT SPRINGS AR 93 74 95 74 / 40 20 10 10 LITTLE ROCK AR 90 74 94 75 / 60 20 20 10 MONTICELLO AR 93 76 96 76 / 50 10 10 10 MOUNT IDA AR 94 74 96 74 / 40 10 10 10 MOUNTAIN HOME AR 87 71 90 72 / 90 30 30 20 NEWPORT AR 86 73 91 74 / 60 30 30 20 PINE BLUFF AR 91 75 95 75 / 50 20 20 10 RUSSELLVILLE AR 90 73 94 74 / 60 20 20 20 SEARCY AR 88 74 92 74 / 60 20 20 20 STUTTGART AR 90 75 94 75 / 60 20 20 10 && .LZK WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH THIS EVENING FOR BAXTER-BOONE-CLEBURNE- FULTON-INDEPENDENCE-IZARD-JOHNSON-MARION-NEWTON-POPE-SEARCY- SHARP-STONE-VAN BUREN. && $$ SHORT TERM...59 / LONG TERM...51
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
355 AM CDT MON AUG 5 2013 .DISCUSSION... 355 AM CDT THE PRIMARY FORECAST CONCERN DURING THE PERIOD WILL BE TIMING THE BEST CHANCES FOR SHOWERS AND THUNDERSTORMS TODAY INTO TONIGHT...AND AGAIN LATE TUESDAY AND INTO WEDNESDAY. TEMPERATURES WILL ALSO A SIGNIFICANT CONCERN OVER THE NEXT FEW DAYS...AS PRECIP/CLOUD COVER AND FRONTAL TIMING WILL HAVE LARGE IMPACTS ON HOW WARM WE GET. CURRENTLY...ATTENTION IS TURNED TO THE UPPER LEVEL DISTURBANCE MOVING ACROSS NORTH DAKOTA AND INTO MINNESOTA PER WATER VAPOR IMAGERY. THIS FEATURE IS ALREADY INDUCING DECENT LOWER LEVEL SOUTHERLY FLOW AND GOOD MOISTURE RETURN ACROSS THE UPPER MIDWEST. KOAX 00 UTC RAOB FROM SUNDAY EVENING INDICATED A 1.6 INCH PWAT...AND THIS DEEPER MOISTURE IS CONTINUING TO OVERSPREAD MUCH OF THE MID AND UPPER MISSISSIPPI VALLEY AHEAD OF THIS UPPER LEVEL WAVE. SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED ACROSS SOUTHERN PORTIONS OF MINNESOTA JUST AHEAD OF THE AREA OF BEST MOISTURE TRANSPORT. THIS ACTIVITY IS EXPECTED TO SHIFT EAST-SOUTHEASTWARD ACROSS SOUTHERN WISCONSIN THROUGH THE MORNING AND INTO THE AFTERNOON HOURS. IT APPEARS THAT THE BEST FOCUS FOR ACTIVITY WILL BE IN SOUTHERN WISCONSIN...BUT SOME ACTIVITY WILL LIKELY GET INTO FAR NORTHERN ILLINOIS BY THIS AFTERNOON. THEREFORE...I HAVE CONTINUED TO FOCUS THE HIGHEST POPS FAR NORTH. ADDITIONAL THUNDERSTORM ACTIVITY COULD ALSO DEVELOP THIS AFTERNOON TO THE SOUTH AND WEST OF THE MAIN BATCH OF SHOWERS AND STORMS ACROSS SOUTHERN WISCONSIN AND FAR NORTHERN ILLINOIS. IT APPEARS THAT A WEAK SURFACE BOUNDARY...POSSIBLY THE OUTFLOW FROM THE NORTHERN ACTIVITY...COULD FOCUS THIS ADDITIONAL ISOLATED TO SCATTERED THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING ACROSS NORTHWESTERN AND POSSIBLY NORTH CENTRAL ILLINOIS. CONFIDENCE IN THE EXTENT OF THIS ADDITIONAL STORM DEVELOPMENT IS LOW AT THIS TIME. HOWEVER...IF THIS ACTIVITY DOES DEVELOP WITHIN THIS INCREASINGLY MOIST/UNSTABLE BOUNDARY LAYER...THESE STORMS COULD HAVE A STRONG TO SEVERE THREAT GIVEN THE STRENGTH OF THE DEEP LAYER SHEAR. THIS WILL HAVE TO BE MONITORED THROUGH THE DAY. IT APPEARS A STRONG TO SEVERE THREAT WOULD REMAIN ACROSS MY WESTERN AREAS...NAMELY NORTH CENTRAL ILLINOIS AND POINTS WEST THIS AFTERNOON. THIS ACTIVITY LOOKS TO CONTINUE INTO THE EVENING ACROSS MUCH OF NORTHERN ILLINOIS. AREAS ACROSS NORTHERN ILLINOIS COULD RECEIVE SOME DECENT RAINFALL AMOUNTS OUT OF THIS ACTIVITY. TEMPERATURES TODAY WILL BE TRICKY AS A RESULT OF THIS CLOUD COVER/PRECIPITATION. CURRENT THINKING IS THAT AREAS ALONG AND SOUTH OF INTERSTATE 80 COULD APPROACH THE LOW 80S THIS AFTERNOON...AS THE THREAT FOR PRECIP WILL BE MUCH LOWER THERE. HOWEVER...TO THE NORTH OF THIS...THE FLOW OFF THE LAKE...ALONG WITH MORE THICK CLOUD COVER AND PRECIP WILL LIKELY KEEP THINGS COOLER...ESPECIALLY ACROSS THE FAR NORTH...WERE TEMPERATURES MAY ONLY TOP OUT AROUND 70. ON TUESDAY...THINGS LOOK TO WARM NICELY. TEMPERATURES AT 850 AND 925 MB CONTINUE TO SUGGEST THE MID TO POSSIBLY UPPER 80S FOR DAYTIME HIGHS. THE THREAT FOR WIDESPREAD CONVECTION DURING THE DAY ALSO STILL APPEARS TO BE SOMEWHAT LIMITED...WITH THE POTENTIAL FOR SOME WEAK CAPPING...AND WITH WHAT APPEARS TO BE A DEARTH OF LARGE SCALE FORCING. WITH THIS IN MIND I CONTINUED WITH SLIGHT CHANCE POPS DURING THE DAY...AS ANY DEVELOPMENT WOULD LIKELY BE OF LOW AERIAL COVERAGE. TUESDAY NIGHT AND INTO WEDNESDAY MORNING STILL APPEARS TO BE THE MAIN SHOW. THE MODELS CONTINUE IN GOOD AGREEMENT WITH DIGGING A SIGNIFICANT UPPER LEVEL LOW FROM OVER THE HUDSON BAY...TO THE NORTH CENTRAL CONUS INTO WEDNESDAY. AS THIS OCCURS...THE MODELS ARE INSISTING THAT A A SERIES OF SHORT WAVES ACROSS THE PACIFIC NORTHWEST...WILL BE INGESTED INTO THE STRONG WESTERLIES ACROSS THE NORTHERN CONUS. ALTHOUGH THERE CONTINUES TO BE SOME UNCERTAINTY WITH THE EXTEND OF THUNDERSTORM DEVELOPMENT ACROSS NORTHERN ILLINOIS TUESDAY NIGHT...IT DOES APPEAR THE ASSOCIATED COLD FRONT FROM THIS SYSTEM WILL PUSH ACROSS THE AREA ON WEDNESDAY MORNING/EARLY AFTERNOON. GIVEN THE VERY HIGH THETA E AIRMASS...WITH 1.9+ PWATS...THAT WILL BE IN PLACE WITHIN THE WARM SECTOR OF THIS STORM...A PERIOD OF HEAVY RAINFALL IS POSSIBLE TUESDAY NIGHT INTO WEDNESDAY. THERE COULD ALSO BE A SEVERE THREAT WITH THIS ACTIVITY. THE TIME OF DAY DOES NOT APPEAR TO BE THE MOST FAVORABLE FOR SEVERE STORMS...BUT WITH A MODERATELY UNSTABLE ENVIRONMENT AND DECENT DEEP LAYER SHEAR...THERE IS AT LEAST A CONDITIONAL THREAT FOR SEVERE THUNDERSTORMS PRIOR TO THE FRONTAL PASSAGE WEDNESDAY. THE SURFACE COLD FRONT WILL BRING AN END TO THE THREAT FOR CONVECTION FROM NORTHWEST TO SOUTHEAST ACROSS THE AREA ON WEDNESDAY. IT APPEARS ALTHOUGH COOL AIR WILL BEGIN FILTER IN ACROSS THE AREA DURING THE DAY...TEMPERATURES COULD ONE AGAIN TOP OUT INTO THE 80S BEFORE THE COOLER AIR ARRIVES. SLIGHTLY COOLER AND DRIER WILL AGAIN MAKE A RETURN TO THE AREA FOR A PERIOD LATER IN THE WEEK. HOWEVER...IT APPEARS THE STRONG WESTERLY UPPER FLOW PATTERN COULD DRIVE A FEW ADDITIONAL DISTURBANCES ACROSS CENTRAL ILLINOIS LATER IN THE WEEK. THIS ACTIVITY LOOKS TO LARGELY REMAIN SOUTH OF THE AREA...BUT I DID PUT SOME SLIGHT CHANCE POPS IN FAR SOUTH TO ACCOUNT FOR THIS POSSIBILITY. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * SOUTHERLY WINDS POSSIBLY SHIFTING SE OR EVEN ESE FOR A PERIOD DURING THE MID TO LATE AFTERNOON INTO THE EARLY EVE. * INCREASING POTENTIAL FOR SHRA/RA BY AFTERNOON WITH DETERIORATING CIGS/VIS INTO LOW MVFR RANGE LATE IN THE DAY INTO THE EVE. * INITIAL LIMITED COVERAGE OF THUNDERSTORMS INCREASING INTO THE EVE. //DISCUSSION...UPDATED 06Z... HIGH PRESSURE CENTERED ACROSS LOWER MI EARLY THIS MORNING WILL SHIFT EAST AS AN ELONGATED LOW PRESSURE TROUGH DEVELOPS FROM THE UPPER MIDWEST INTO THE WESTERN PLAINS. AN UPPER LEVEL DISTURBANCE WILL RIDE A STRONG JET INTO THE AREA BY LATE MORNING AND INTO THE AFTERNOON...AND THIS IS RESPONSIBLE FOR THE EARLY MORNING STORMS ACROSS MN. IT IS POSSIBLE REMNANTS OF SOME OF THESE STORMS APPROACH THE AREA AS EARLY AS MID-MORNING...BUT THE MOST FAVORED TIME FOR RA/SHRA COVERAGE WILL BE THIS AFTERNOON. THERE IS A STRONG SIGNAL FOR MVFR CIGS...BUT HOW LOW IN THAT CATEGORY VARIES. IF RAIN IS MORE STEADY THEN AROUND 1000 FT IS LIKELY. AS FOR THUNDER...WHILE SOME SCATTERED EMBEDDED THUNDER IS FAVORED IN THE AFTERNOON...THE CHANCES ACTUALLY INCREASE LATE IN THE DAY INTO THE EVE. A SECOND SHORTWAVE...OR AN EXTENSION FROM THE FIRST...MAY TRIGGER SCATTERED STORMS DURING THAT TIME AND THAT IS WHY PROB30S FOR TSRA ARE IN THE TAFS. EVEN IF THESE DEVELOP...THE AMOUNT OF COVERAGE IS HIGHLY UNCERTAIN AT THIS TIME. SOUTHERLY WINDS ARE PREVALENT IN ALL HOURS OF THE TAF...HOWEVER IT IS POSSIBLE FOR A SHIFT TO SE OR ESE FOR FAR NE IL SITES...INCLUDING ORD AND MDW. THIS WOULD BE LIKELY DURING THE LATER AFTERNOON AND DEPENDS IN SOME PART HOW MUCH RAIN COVERAGE THERE IS. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE IN TIMING PRECIPITATION AND ASSOCIATED CIG/VIS TRENDS. LOW CONFIDENCE ON HOW LOW CIGS WILL DROP...BUT LIKELY NEARING AT LEAST 1500 FT IF RAIN OCCURS AS FORECAST. * LOW CONFIDENCE THAT TSRA WILL DIRECTLY IMPACT TERMINALS...MEDIUM CONFIDENCE IN AT LEAST A FEW TSRA IN THE AREA PARTICULARLY LATER TODAY INTO THIS EVE. * LOW CONFIDENCE IN WIND TRENDS AFTER 20Z TODAY. //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY AND WEDNESDAY...CHANCE OF TSRA. PERIODS OF MVFR/IFR CIG/VIS POSSIBLE. THURSDAY THROUGH SATURDAY...VFR. MTF/RATZER && .MARINE... 258 AM CDT AS HIGH PRESSURE MOVES EAST FROM LOWER MI TODAY SOUTHERLY WINDS WILL ENVELOP THE LAKE AS NEARLY STATIONARY LOW PRESSURE EVOLVES OVER MN. THIS WIND WILL LIKELY HAVE A HANDFUL OF GUSTS TO NEAR 25 KT OVER THE OPEN WATER OF THE SOUTH. AS THE LOW PRESSURE TO OUR NORTHWEST EVENTUALLY MOVES TO NEAR ST JAMES BAY WEDNESDAY MORNING...A COOL FRONT IS EXPECTED TO SWING ACROSS THE LAKE LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. THE COOL AIR ADVECTION IN THE WAKE OF THIS MAY ENABLE SOME 20-25 KT GUSTS ACROSS THE NORTH ON WEDNESDAY. HIGH PRESSURE WILL THEN BUILD IN FOR THURSDAY FOLLOWED BY ANOTHER LIKELY LOW PRESSURE TRANSLATING NORTHEAST INTO CANADA SOMETIME LATE IN THE WEEK. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 330 AM CDT Mon Aug 5 2013 .DISCUSSION... ISSUED 330 AM CDT Mon Aug 5 2013 SHORT TERM...Today through Thursday night Some patchy fog in southeast IL with Effingham, Terre Haute and Mount Carmel Airports having visibilities around 2 miles, should lift by mid morning. 1020 mb high pressure over Ohio and eastern lower Michigan to drift east into the mid Atlantic states by sunset with return sse flow developing over IL and bringing warmer and more humid air into region next few days. Central IL appears to be caught in between two MCS`s today with one over the upper MS valley affecting northeast IL while another MCS over the Ozarks in SW MO to stay sw of central/se IL. So most appears appear to stay dry today and models have trended drier today as well. Will just carry 20% chance of a shower or thunderstorm from I-55 west with best chances over northern 3 counties of Knox, Stark and Marshall late this morning & afternoon which will be on the southern fringe of the northern MCS system. Highs in the lower 80s this afternoon with dewpoints rising into the 60s...so getting more humid then yesterday. Skies becoming partly to mostly cloudy with more sunshine over eastern IL especially near Wabash River. Models continue to keep much of central/se IL dry tonight and will only carry small chances of showers and thunderstorms over mainly areas from I-74 ne. Central IL will continue to be in between two weather systems to our north and sw over MO. Lows tonight in the mid to upper 60s. Have isolated showers and thunderstorms possible Tuesday morning then a 30% chance Tuesday afternoon with warm and humid conditions with temps in the 80s and dewpoints into the lower 70s with southerly flow. Continue likely chances of convection Tuesday night with better chance of MCS to impact region especially by overnight Tue night and SPC has slight chance of severe storms (15%) from Knox county nw into Iowa. A cold front to press southeast through central IL Wednesday and continue a good chance of convection especially from I-72 south. Another warm and humid day Wed with highs in the mid 80s central IL and upper 80s southeast IL where dewpoints 70-75F. Models have trended wetter over area Wed night through Friday especially over southeast IL as frontal boundary becomes quasi stationary south of IL and disturbances tracking eastward along it. LONG TERM...Friday through Sunday night Drier weather to return to region by Friday night into most of this weekend as 1022 mb high pressure settles into the great lakes region. Temps and humidity levels should also be lower during this time frame. 07 && .AVIATION... ISSUED 1110 PM CDT Sun Aug 4 2013 Little change from previous discussion. Except for the 08z-12z time frame where some lower cigs/vsbys will be possible acrs our southern TAF sites, VFR conditions are expected through the remainder of this forecast period (06z Tue). Patches of mid and high level clouds continue to stream southeast into the area late this evening. Larger band of stratocu seen on satellite edging northeast with bases of cigs in the 4000-6000 foot range. In addition, the past few runs of the HRRR model indicating some lower vsbys in fog and even some stratus developing just south of SPI in the 09z-11z time frame. Current temp-dew point spreads suggest the possibility late tonight...after 08z in SPI. Remnants of MCS which passed acrs SE Mo into extreme southern IL continues to track away from area but will have to watch for some stratus and possibly some lower cigs to form on its northern periphery and drift northwest as the boundary layer winds turn more into an east-southeast direction. At this point will keep vsbys around 5 miles and introduce some lower clouds with bases around 1000 feet late tonight and for now keep this threat in SPI. Scattered-broken cigs at 4000-6000 feet will continue during the day as an upper level system pushes to our north. Will continue with VCSH mainly across our northern TAF sites but coverage appears too limited at this time to go with any tempo groups. Surface winds will continue to be light and variable tonight and then swing into a southerly direction on Monday with speeds of 8 to 13 kts. Smith && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1255 AM CDT MON AUG 5 2013 .DISCUSSION... 916 PM CDT EVENING UPDATE: MADE A FEW CHANGES TO FORECAST. BUMPED UP SKY COVER THIS EVENING WITH SHORTWAVE OVERHEAD THAT SHOULD BE OFF TO THE EAST BY OR AFTER MIDNIGHT. THERE HAVE EVEN BEEN A FEW OBS OF SPRINKLES FALLING FROM THE MID DECK BUT DID NOT FEEL THIS WERE WORTH MENTIONING IN UPDATED ZONES. TEMPERATURES HAVE BEEN TRENDING WELL SO ONLY MADE MINOR TWEAKS TO GOING LOW TEMPERATURE FORECAST...MAINLY TO RAISE TEMPERATURES A BIT IN AND NEAR CHICAGO. ALSO REMOVED SLIGHT POP MENTION FROM FAR NORTHERN ILLINOIS TOWARD DAYBREAK AS FORECAST SOUNDINGS SHOW PLENTY OF DRY AIR TO OVERCOME FROM EXPECTED DECAYING MCS THAT WILL ARRIVE TOMORROW. ALSO...THERE IS NO LOW LEVEL JET SUPPORT FOR MOISTURE TRANSPORT...WITH IT BEING FOCUSED OFF TO THE WEST THROUGH THE NIGHT INTO EARLY MONDAY. THUS ALSO TRENDED POPS TO SLOW ARRIVAL OF SHOWERS TOMORROW MORNING. HOWEVER...THERE IS GOOD AGREEMENT AMONGST GUIDANCE ON STRONG 850 MB MOISTURE TRANSPORT PUSHING INTO NORTHERN IL ESPECIALLY DURING THE AFTERNOON THAT SUPPORTS GOING HIGH LIKELY/LOW CATEGORICAL POPS FOR IN GOING FORECAST. VERY LIMITED INSTABILITY ON FORECAST SOUNDINGS WILL LIKELY KEEP THE THUNDER ISOLATED TOMORROW AND EMBEDDED WITHIN THE SHOWER ACTIVITY. RC //PREV DISCUSSION... 257 PM CDT AFTER A WARM AND UNSETTLED START TO THE WEEK...A FRONTAL PASSAGE ON WEDNESDAY WILL USHER IN COOLER AND DRIER AIR FOR THE SECOND HALF OF THE WEEK INTO NEXT WEEKEND. WEATHER FOR THE UPCOMING WEEK WILL BE INFLUENCED BY AN UPPER LEVEL RIDGE ACROSS THE SOUTHERN AND WESTERN CONUS AND AN UPPER LOW FORMING OVER HUDSON BAY AND THEN DIGGING ACROSS MANITOBA...ONTARIO...AND QUEBEC. THE LARGE SCALE INTERACTIONS BETWEEN THESE FEATURES...AND THEIR RELATIVE POSITIONS OVER THE NEXT FEW DAYS...APPEAR TO BE HANDLED IN A SIMILAR MANNER BY VARIOUS DETERMINISTIC MODELS AND THE GFS ENSEMBLE. THAT PROVIDES CONFIDENCE FOR THE OVERALL TRENDS DURING THE WEEK...BUT WITH LOWER LEVELS BEING SOMEWHAT DIFFUSE...THE TIMING AND LOCATION OF SMALLER SCALE FEATURES WILL TAKE SOME WORK TO PIN DOWN. A SHORTWAVE EMBEDDED IN THE BROAD WESTERN CONUS RIDGE HELPED LIGHT UP SEEMINGLY THE ENTIRE HIGH COUNTRY FROM ALBERTA INTO WESTERN MEXICO DURING PEAK HEATING LATE YESTERDAY. TWO DISTINCT AREAS PERSISTED OVERNIGHT INTO EARLY THIS MORNING...ONE FOCUSED OVER KANSAS AND THE OTHER IN THE DAKOTAS. THE SOUTHERN AREA HAS SHOWN A MUCH GREATER ABILITY TO HANG TOGETHER OVER MISSOURI TODAY BY VIRTUE OF ITS ACCESS TO MORE FAVORABLE GULF MOISTURE WRAPPING AROUND THE SOUTHERN EDGE OF A BROAD SURFACE HIGH THAT WAS CENTERED OVER LAKE MICHIGAN AS OF MID DAY BUT IS FORECAST TO MOVE INTO THE OHIO VALLEY BY TOMORROW MORNING. FOR TONIGHT AND MONDAY...THE GFS/ECMWF DEPICT A BROAD SHORTWAVE DEVELOPING OVER NORTHERN MONTANA THIS AFTERNOON IN AN AREA WHERE CIRCULATION IS EVIDENT IN LATEST WV IMAGERY. A CORRESPONDING 850MB TROUGH IS DEPICTED JUST EAST OF THIS AREA. THE UPPER WAVE WILL DROP THROUGH THE DAKOTAS AND APPARENTLY HELP REDEVELOP THE REMNANTS OF THE MIDLEVEL WAVE OVER THE EASTERN DAKOTAS. TOGETHER BOTH OF THESE FEATURES MOVE TOWARD THE LOCAL AREA OVERNIGHT...OVERTAKING THE 850MB TROUGH AND RUNNING AHEAD OF THE BEST MOISTURE AT LOWER LEVELS DUE TO THE LINGERING EFFECTS OF THE SURFACE RIDGE PARKED OVERHEAD TODAY. SO TOMORROW LOOKS TO START DRY ACROSS MOST OF THE FORECAST AREA. SHOWERS AND SOME THUNDERSTORMS LIKELY WILL SPREAD ACROSS AT LEAST THE NORTHERN HALF OF THE CWA BY AFTERNOON...KEEPING TEMPERATURES DOWN...AS THE 850MB TROUGH MOVES OVERHEAD AND LOWER LEVELS FINALLY SATURATE. AS FOR SEVERE STORMS...THE LOCAL AREA IS EXPECTED TO BE UNDER A BROAD AREA OF MARGINALLY FAVORABLE DEEP LAYER SPEED AND DIRECTIONAL SHEAR...BUT THE BETTER CHANCE FOR ORGANIZED STRONG CONVECTION SHOULD BE WEST AND THEN SOUTH OF THE AREA WHERE THE DEEP LAYER SHEAR OVERLAPS THE MORE PRONOUNCED LOW LEVEL INSTABILITY. FOR MONDAY NIGHT AND TUESDAY...A LOSS OF UPPER LEVEL SUPPORT...WEAK RIDGING AT MID AND LOWER LEVELS...AND DRYING FROM SUBSIDENCE ALOFT...ALL WOULD APPEAR UNFAVORABLE FOR THE MAINTENANCE OF SHOWERS PAST MIDNIGHT AND INTO TUESDAY DESPITE PLENTY OF MOISTURE AT THE SURFACE. IT IS HOWEVER POSSIBLE THAT THIS SFC MOISTURE COULD SUPPORT SOME PATCHY FOG EARLY TUESDAY. WITH SOUTH TO SOUTHWESTERLY FLOW ACROSS MOST OF THE AREA...TUESDAY AFTERNOON SHOULD ALSO BE PRETTY WARM AND HUMID...SUPPORTING HEAT INDICIES IN THE 90S FOR SOME LOCATIONS. FOR TUESDAY NIGHT AND WEDNESDAY...TSRA CHANCES AGAIN INCREASE...BUT SO DOES UNCERTAINTY. AS MENTIONED BEFORE...GFS/ECM/NAM/GEM ALL SHOW THE UPPER LOW DROPPING OUT OF HUDSON BAY INTO THE MANITOBA/ONTARIO AREA WHILE THE UPPER RIDGE FLATTENS ACROSS THE SOUTHERN CONUS. SHORTWAVES EMBEDDED IN THE SOMEWHAT ZONAL FLOW BETWEEN THESE FEATURES WILL HAVE ACCESS TO PLENTY OF MOISTURE AT LOW LEVELS...BUT IT IS NOT CLEAR IF SUCH WAVES WILL BE PRESENT OR WHERE EXACTLY THEY WILL TRAVERSE. WILL MAINTAIN HIGH END CHANCE POPS AS IN PREVIOUS FORECAST FOR MOST OF THE AREA TUESDAY NIGHT BUT FAVOR SOUTHERN PORTIONS WITH LOW END LIKELIES WHERE MODELS ARE HINTING AT A MORE LIKELY SHORTWAVE/MCS TRACK. A REALLY DIFFUSE COLD FRONT THEN CROSSES THE AREA DURING THE DAY WEDNESDAY WITHOUT MUCH LARGE SCALE SUPPORT ALOFT...SO HAVE MAINTAINED CHANCE POPS WITH THE GREATER VALUES EAST OF THIS FEATURE. ALSO HAVE REFLECTED THIS BOUNDARY IN THE MAX TEMP FCST...WITH UPPER 70S TO AROUND 80 NORTH AND MID 80S SOUTH. FOR THURSDAY AND FRIDAY...THE FRONT PUSHING THROUGH WEDNESDAY WILL DRY THINGS OUT AND COOL THE DAYTIME HIGHS THURSDAY AND FRIDAY. WILL MAINTAIN SOME SLIGHT CHANCE POPS FOR SOUTHEASTERN AREAS WEDNESDAY NIGHT TO ACCOUNT FOR UNCERTAINTIES IN TIMING...BUT THEN IGNORE THE GEM AND KEEP PRECIP OUT OF THE FORECAST THROUGH THE END OF THE WORKWEEK. FOR NEXT WEEKEND...COOLER DAYTIME HIGHS PERSIST WITH NORTHERLY FLOW AT THE SURFACE. THE UPPER LOW WILL ALSO CONTINUE ITS SPIN ACROSS THE NORTHERN GREAT LAKES...GENERATING BROAD CYCLONIC FLOW AND PROBABLY SOME WIDESPREAD AFTERNOON CLOUDINESS AND ISOLATED POPUP SHOWERS. OVERALL THERE DOES NOT APPEAR TO BE ENOUGH MOISTURE AT LOW LEVELS TO SUPPORT MENTIONABLE PRECIP AT THIS TIME RANGE. LENNING && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * SOUTHERLY WINDS POSSIBLY SHIFTING SE OR EVEN ESE FOR A PERIOD DURING THE MID TO LATE AFTERNOON INTO THE EARLY EVE. * INCREASING POTENTIAL FOR SHRA/RA BY AFTERNOON WITH DETERIORATING CIGS/VIS INTO LOW MVFR RANGE LATE IN THE DAY INTO THE EVE. * INITIAL LIMITED COVERAGE OF THUNDERSTORMS INCREASING INTO THE EVE. //DISCUSSION...UPDATED 06Z... HIGH PRESSURE CENTERED ACROSS LOWER MI EARLY THIS MORNING WILL SHIFT EAST AS AN ELONGATED LOW PRESSURE TROUGH DEVELOPS FROM THE UPPER MIDWEST INTO THE WESTERN PLAINS. AN UPPER LEVEL DISTURBANCE WILL RIDE A STRONG JET INTO THE AREA BY LATE MORNING AND INTO THE AFTERNOON...AND THIS IS RESPONSIBLE FOR THE EARLY MORNING STORMS ACROSS MN. IT IS POSSIBLE REMNANTS OF SOME OF THESE STORMS APPROACH THE AREA AS EARLY AS MID-MORNING...BUT THE MOST FAVORED TIME FOR RA/SHRA COVERAGE WILL BE THIS AFTERNOON. THERE IS A STRONG SIGNAL FOR MVFR CIGS...BUT HOW LOW IN THAT CATEGORY VARIES. IF RAIN IS MORE STEADY THEN AROUND 1000 FT IS LIKELY. AS FOR THUNDER...WHILE SOME SCATTERED EMBEDDED THUNDER IS FAVORED IN THE AFTERNOON...THE CHANCES ACTUALLY INCREASE LATE IN THE DAY INTO THE EVE. A SECOND SHORTWAVE...OR AN EXTENSION FROM THE FIRST...MAY TRIGGER SCATTERED STORMS DURING THAT TIME AND THAT IS WHY PROB30S FOR TSRA ARE IN THE TAFS. EVEN IF THESE DEVELOP...THE AMOUNT OF COVERAGE IS HIGHLY UNCERTAIN AT THIS TIME. SOUTHERLY WINDS ARE PREVALENT IN ALL HOURS OF THE TAF...HOWEVER IT IS POSSIBLE FOR A SHIFT TO SE OR ESE FOR FAR NE IL SITES...INCLUDING ORD AND MDW. THIS WOULD BE LIKELY DURING THE LATER AFTERNOON AND DEPENDS IN SOME PART HOW MUCH RAIN COVERAGE THERE IS. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE IN TIMING PRECIPITATION AND ASSOCIATED CIG/VIS TRENDS. LOW CONFIDENCE ON HOW LOW CIGS WILL DROP...BUT LIKELY NEARING AT LEAST 1500 FT IF RAIN OCCURS AS FORECAST. * LOW CONFIDENCE THAT TSRA WILL DIRECTLY IMPACT TERMINALS...MEDIUM CONFIDENCE IN AT LEAST A FEW TSRA IN THE AREA PARTICULARLY LATER TODAY INTO THIS EVE. * LOW CONFIDENCE IN WIND TRENDS AFTER 20Z TODAY. //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY AND WEDNESDAY...CHANCE OF TSRA. PERIODS OF MVFR/IFR CIG/VIS POSSIBLE. THURSDAY THROUGH SATURDAY...VFR. MTF/RATZER && .MARINE... 250 PM CDT WINDS WILL BECOME LIGHT TONIGHT AS HIGH PRESSURE CENTERED OVER NORTHERN WI MOVES SE ACROSS LAKE MI THIS EVENING...AND THEN BECOME SOUTHERLY AND FRESHEN OVERNIGHT AND MONDAY AS THE HIGH MOVES OFF TO OH BY DAWN AND AN AREA OF LOW PRESSURE MOVES SLOWLY E FROM THE NORTHERN AND CENTRAL PLAINS TO THE UPPER MS AND MID MO VALLEYS DURING MONDAY. THIS LOW WEAKENS MONDAY NIGHT AS IT CONTINUES SLOWLY E INTO THE UPPER MIDWEST. ANOTHER LOW WILL MOVE E FROM WI TO MI U.P. TUE. AS THIS LOW MOVES NE INTO ONTARIO WED A COLD FRONT WILL MOVE ACROSS LAKE MI SHIFTING WINDS FROM SOUTHERLY TO OUT OF THE NE AND N AND FRESHEN AS HIGH PRESSURE SLOWLY SETTLES SE FROM THE UPPER MIDWEST AND MID MO VALLEY. THE HIGH MOVES OVER LAKE MI THU...REACHING THE MIDWEST AND MID MS VALLEY LATE THU NIGHT. LOW PRESSURE MOVING E ACROSS ONTARIO WILL MOVE ANOTHER COLD FRONT ACROSS THE LAKE LATE FRI AND FRI NIGHT. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1115 PM CDT Sun Aug 4 2013 .DISCUSSION... ISSUED 845 PM CDT Sun Aug 4 2013 High pressure continues to slowly edge east of our area early this evening. Very pleasant conditions prevail across the region with mild temperatures and comfortable humidities. As the fair weather system continues to move away tonight, our winds will turn more into the south by morning which should allow dew points to rise back into the 60s most of the area by afternoon. Satellite data depicting a rather vigorous shortwave over North Dakaota, which is forecast to track east into the Great Lakes on Monday increasing the chances for showers and thunderstorms, especially across the north. Further to our southwest, another convective complex is expected to form on the nose of the low level jet late tonight and track east and then southeast across parts of southern Missouri. 00Z ILX sounding still indicating quite a bit of dry air in place thanks to the departing area of high pressure with most models holding off any threat for rain until Monday morning at the earliest. Current zone forecast handling the evening trends quite well, so no zone update will be needed. && .AVIATION... ISSUED 1110 PM CDT Sun Aug 4 2013 Little change from previous discussion. Except for the 08z-12z time frame where some lower cigs/vsbys will be possible acrs our southern TAF sites, VFR conditions are expected through the remainder of this forecast period (06z Tue). Patches of mid and high level clouds continue to stream southeast into the area late this evening. Larger band of stratocu seen on satellite edging northeast with bases of cigs in the 4000-6000 foot range. In addition, the past few runs of the HRRR model indicating some lower vsbys in fog and even some stratus developing just south of SPI in the 09z-11z time frame. Current temp-dew point spreads suggest the possibility late tonight...after 08z in SPI. Remnants of MCS which passed acrs SE Mo into extreme southern IL continues to track away from area but will have to watch for some stratus and possibly some lower cigs to form on its northern periphery and drift northwest as the boundary layer winds turn more into an east-southeast direction. At this point will keep vsbys around 5 miles and introduce some lower clouds with bases around 1000 feet late tonight and for now keep this threat in SPI. Scattered-broken cigs at 4000-6000 feet will continue during the day as an upper level system pushes to our north. Will continue with VCSH mainly across our northern TAF sites but coverage appears too limited at this time to go with any tempo groups. Surface winds will continue to be light and variable tonight and then swing into a southerly direction on Monday with speeds of 8 to 13 kts. Smith && .PREV DISCUSSION... ISSUED 250 PM CDT Sun Aug 4 2013 High pressure slowly drifting across the Great Lakes early this afternoon, producing some diurnal cumulus. High clouds continue to stream across the south half of the state, from convection over southwest Missouri that has been on the wane the last few hours. Have had some good mixing of the air aloft which has brought surface dew points down into the lower to mid 50s, as early afternoon air temperatures reached the 75-80 degree range. Aloft, water vapor imagery showing a shortwave tracking along the periphery of an upper high centered over Texas, with the wave moving through eastern Nebraska and western Iowa. A second wave was tracking along the Montana/Saskatchewan border. The primary forecast challenge continues to be with timing of shower and thunderstorm activity the next few days. SHORT TERM...Tonight through Wednesday... Model guidance has generally settled into the thought of producing two separate MCS clusters overnight, one with the Montana wave and tracking to our north, and the other sliding southeast across Missouri in association with the Nebraska wave. Not looking terribly promising in between at the moment, with the best chances of seeing anything in our area being with the northern cluster on Monday into early evening, so have focused most of the rain chances with that feature. Have limited rain chances to slights at best over the remainder of the area into early Tuesday. The main rain maker in our area will be with the primary cold front toward midweek, as a strong upper wave swings across the Great Lakes. Some convective feedback on the GFS is resulting in a slower frontal passage, but the general model consensus a passage through our forecast area late Tuesday night through about midday Wednesday. Will have the highest rain chances over the entire area Tuesday night, and lingering into Wednesday across the southeast quarter. Frontal boundary will not be going through at an optimal time for severe weather, but some stronger winds will be possible with a few of the storms. Greatest potential for heavy rain will be during this period though, as precipitable water values rise to around 2-2.25 inches. LONG TERM...Wednesday night through Sunday... Frontal boundary to slow down Wednesday night as it starts to parallel the upper flow. Latest ECMWF more generous with spreading the rain back northward as ripples of low pressure ride along the boundary, while the GFS keeps most of the precip to our south Wednesday night and Thursday. Have kept some low chances of around 30% across southeast Illinois to account for this. The large upper low which will be spinning over south central Canada much of the week will finally swing eastward late in the week, with an associated frontal boundary sweeping through the state Friday night. With the old boundary south of us intercepting any moisture return, this frontal passage will likely be dry. These dry conditions are expected to linger into next weekend, as high pressure builds southeast into the Midwest. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
349 AM CDT MON AUG 5 2013 .SYNOPSIS... ISSUED AT 348 AM CDT MON AUG 5 2013 LATEST SFC ANALYSIS WAS INDICATING DEPARTING HIGH PRESSURE CENTERED OVER LOWER MI INTO NORTHWESTERN OH...WHILE RETURN FLOW CONTINUED TO ORGANIZE UP THE PLAINS AND JUST EAST OF THE MO RVR VALLEY. UPPER 60 TO AROUND 70 SFC DPTS WERE WRAPPING UP AROUND THE WESTERN FLANK OF THE RIDGE FROM THE LOWER MS RVR VALLEY...UP ACRS NEB. CURRENT MESOANALYSIS WAS INDICATING ELEVATED PLUME OF HIGHER THTA-E AIR GENERALLY ACRS THE SAME REGIONS...MAYBE GETTING PUSHED A BIT FURTHER EAST AND NORTHEAST OF THE THE SFC LAYER ACRS THE WESTERN THIRD OF IA. ALOFT...NORTHWEST FLOW CONTINUED WITH AN EMBEDDED WAVE PUSHING ACRS NORTHWESTERN INTO WEST CENTRAL MN DRIVING MAINLY AN ELEVATED MCS ACRS THE SOUTHEAST HALF OF MN. THIS ACTIVITY DROPPING SOUTHEAST ALONG THTA-E GRADIENT AND SHOULD MAKE IT INTO THE NORTHWESTERN AND NORTHERN PORTIONS OF THE DVN CWA THIS MORNING...POSSIBLY INDEPENDENCE BY 1030Z. OTHER STRONG THTA-E ADVECTION AND CONVERGENT FIELDS WERE FUELING HEAVY CONVECTIVE BANDS ACRS KS INTO SOUTHERN MO. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 348 AM CDT MON AUG 5 2013 TODAY...WILL WALK IN PORTION OF THE UPSTREAM MN/IA BORDER MCS INTO THE NORTHWESTERN TO NORTHERN THIRD OF THE DVN CWA THIS MORNING... BUT AS IT GETS AWAY FROM BETTER SUPPORT/H85 JET THTA-E FEED FEEL THE GENERAL WEAKENING TREND THAT THE LATEST RUN HRRR SUGGESTS WILL VERIFY AS IT SPILLS ALONG AND SOUTH OF HWY 30 AFTER 12Z THROUGH 14Z. BUT MAY STILL HAVE TO WATCH FOR A STRONG STORM IN THE FAR NORTHWESTERN CWA AS IT ARRIVES THOUGH AROUND 515 TO 530 AM CDT. WILL THEN WALK THE REST OF THE MCS AGAIN PROBABLY IN A DIURNALLY WEAKENING MODE ACRS THE NORTHERN THIRD OR A LITTLE MORE OF THE DVN CWA THROUGH LATE MORNING WITH HIGHEST POPS NORTH OF HWY 30. THEN AS CONVECTIVE DEBRIS CLEARS AND WARM AIR/THTA-E ADVECTION CONTINUE ACRS THE AREA INTO THE AFTERNOON...PORTIONS OF THE DVN CWA MAY BECOME RELATIVELY UNSTABLE ESPECIALLY THE SOUTHWESTERN HALF. REMNANT OUTFLOW BOUNDARIES AND A SECONDARY TYPE WARM FRONT MAY LAY OUT ACRS THE AREA AND ACT AS POTENTIAL FOCAL POINTS FOR AFTERNOON AND EARLY EVENING CONVECTION TO REFIRE ON. SOUTHERN PORTION OF THE NW MN WAVE AND RATHER VIGOROUS MID/UPPER JET STREAKS STREAMING ALONG AND JUST NORTH OF THE AREA COULD KICK OFF SCTRD STORMS THIS AFTERNOON WITH AN ISOLATED THREAT OF STRONG TO SVR STORMS LIKE SPC IS HINTING AT DUE TO INCREASING VERTICAL SHEAR PROFILES. BUT MUCH WILL DEPEND ON EVENTUAL HIGH TEMPS AROUND 80 OR WARMER AND IF SFC DPTS CAN MAKE IT AT LEAST INTO THE UPPER 60S. WILL GO WITH LOW TO MODERATE CHC POPS THIS AFTERNOON BECAUSE OF COVERAGE/INSTABILITY CONCERNS. HIGHS COOLER IN THE MID TO UPPER 70S IN THE NORTHEASTERN THIRD...TO THE LOW TO MID 80S IN THE SOUTHWEST WITH INCREASING BOUNDARY LAYER HUMIDITY. TONIGHT...WITH THE WAVE/VORT MAX SHEARING OFF TO THE EAST OF THE AREA...END OF LIFTING MECHANISMS AND DIURNAL PROCESSES SHOULD BRING ABOUT A DECREASE OF ANY PRECIP ACTIVITY AS THE EVENING PROGRESSES. NOCTURNAL LLJ PROGGED TO FOCUS BACK TO THE WEST AND SOUTH OF THE AREA AS WELL. WITH HIGHER DPTS IN PLACE AND LIGHT VARIABLE FLOW... ANY CLOUD CLEAR OUT MAY FOSTER FOG PRODUCTION ESPECIALLY IN AREAS THAT MANAGE TO GET SOME NEEDED RAINFALL. FOR NOW WILL JUST BLANKET THE CWA WITH PATCHY LATE NIGHT FOG WORDING. LOWS IN THE MID TO UPPER 60S IN MOST OF THE LOCAL FCST AREA. ..12.. .LONG TERM...(TUESDAY THROUGH NEXT SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 A SHORT WAVE AND COOL FRONT MOVING OUT OF THE NORTHERN PLAINS TUESDAY AND THROUGH THE MID AND UPPER MISSISSIPPI VALLEY BY WEDNESDAY MORNING WILL BRING A CHANCE OF THE THUNDERSTORMS TO THE REGION. TEMPERATURES AHEAD OF THE FRONT SHOULD RISE INTO THE 80S WITH DEWPOINTS IN THE UPPER 60S AND LOW 70S. SURFACE BASED CAPES BY MID AFTERNOON ARE EXPECTED TO BE AROUND 2K J/KG OVER MOST OF THE AREA. WITH THE INSTABILITY IN PLACE AND SOME WEAK UPPER FORCING SPREADING IN AHEAD OF THE MAIN SHORTWAVE...SOME ISOLATED TO SCATTERED STRONG STORMS WILL BE POSSIBLE DURING THE AFTERNOON AND HAVE INCLUDED SLIGHT CHANCE TO LOW CHANCE POPS FOR THE ENTIRE AREA AFTER 18Z. THE MAIN FORCING IS PROGGED TO MOVE THROUGH LATE TUESDAY NIGHT AND HAVE KEPT HIGH CHANCE TO LIKELY POPS DURING THIS PERIOD. THERE SHOULD BE ENOUGH INSTABILITY WITH MODERATE DEEP LAYER SHEAR FOR A RISK OF SEVERE STORMS OVERNIGHT. THE FRONT AND UPPER WAVE WILL BE EAST OF THE AREA BY WEDNESDAY MORNING BUT THE LOW LEVEL MOISTURE WILL BE SLOW TO LEAVE IN THE WEAK FLOW BEHIND THE FRONT SO HELD ON TO SOME LOW POPS EAST AND SOUTH WEDNESDAY. FOR THE REST OF THE FORECAST PERIOD NORTHWEST FLOW WILL REMAIN IN PLACE KEEPING MAINLY DRY AND COOLER THAN NORMAL CONDITIONS OVER THE AREA. THE MODELS ARE SHOWING A COUPLE OF WAVES MOVING OUT OF THE SOUTHERN ROCKIES AND THROUGH THE MID AND LOW MISSISSIPPI VALLEY WEDNESDAY THROUGH FRIDAY. THE NORTHERN EDGE OF THE PRECIPITATION BRUSHES THE FAR SOUTHERN COUNTIES SO KEPT SOME SLIGHT CHANCE POPS GOING IN THE SOUTH MID TO LATE WEEK. BROAD BRUSH SLIGHT CHANCE POPS WERE PLACED OVER THE FORECAST AREA FOR SUNDAY WITH THE ECMWF SHOWING A SHORT WAVE MOVING OUT OF THE NORTHERN PLAINS INTO THE UPPER MS VALLEY SUNDAY AND SUNDAY NIGHT. DLF && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1150 PM CDT SUN AUG 4 2013 THUNDERSTORMS IN SOUTHERN MINNESOTA ARE EXPECTED TO TRACK SOUTHEASTWARD INTO NORTHEAST IOWA BY 12Z...POTENTIALLY AFFECTING AREA TAF SITES NORTH OF I80 INCLUDING DBQ...CID...AND POSSIBLY MLI. OTHERWISE...VFR CIGS WILL CONTINUE BEFORE THE STORMS...WITH MVFR CIGS LINGERING AFTERWARD THROUGH MUCH OF MONDAY. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...12 SHORT TERM...12 LONG TERM...DLF AVIATION...DMD
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
328 AM CDT MON AUG 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 330 AM CDT MON AUG 5 2013 A 30 KT LLJ NOSING UP INTO SW MN EARLY THIS MORNING HAS FORCED A FAIRLY BROAD SHIELD OF SHOWERS WITH EMBEDDED THUNDERSTORMS THAT HAS BEEN STEADILY MAKING ITS WAY ACROSS MN THIS MORNING. ELEVATED INSTABILITY HAS NOT MADE MUCH PROGRESS NE THOUGH...WHICH IS WHY ANY DEEPER CONVECTION HAS ESSENTIALLY BEEN CRAWLING AROUND THE MPX CWA BORDER WITH FSD. MOST OF THE HOPWRF MEMBERS ALONG WITH THE LOCAL MPX-WRF HAVE ALL DONE A DECENT JOB IN CAPTURING WHAT HAS HAPPENED SO FAR OVERNIGHT IN TERMS PRECIP PLACEMENT...THEY HAVE ALL JUST BEEN ABOUT 2 HOURS BEHIND SCHEDULE. AS A RESULT...WAS FAIRLY AGGRESSIVE WITH MOVING LIKELY OR BETTER POPS OUT OF THE AREA THIS MORNING. BASED ON CURRENT MOVEMENT...BACK EDGE OF THE SHOWERS OVER CENTRAL MN WILL BE CLEARING THE EAU AREA AROUND 11Z...SO CERTAINLY DOES NOT MAKE MUCH SENSE TO HAVE MUCH IN THE WAY OF POPS BEYOND 15Z. THE ONLY POTENTIAL PROBLEM FOR THIS FASTER PROGRESSION OF LOWER POPS THROUGH THE AREA IS THE FACT THAT THERE IS A SFC TROUGH/COLD FRONT FEATURE CURRENTLY MOVING THROUGH THE ERN DAKOTAS THAT THE HRRR IS TRYING TO DEVELOP ANOTHER LINE OF CONVECTION ALONG LATER THIS MORNING. HAVE SEEN A FEW SPECKLES ON THE RADAR TO THE WEST OF THE MAIN PRECIP SHIELD OVER WRN MN...BUT TO THIS POINT WE HAVE NOT SEEN ANYTHING TO SUGGEST STORMS ON THE ORDER OF THE WHAT THE 5Z AND 6Z VERSIONS OF THE HRRR HAVE BEEN SHOWING DEVELOPING NEAR THE MN/SD. WITH MAIN PUSH OF MOISTURE TRANSPORT FOLLOWING THE PRECIP SHIELD EAST AND WITH AT LEAST SOME DEGREE OF OVERTURNING OCCURRING WITH THE FIRST ROUND OF RAIN...HAVE FAVORED THE FASTER DEPARTURE OF PRECIP...THOUGH THIS MAY NEED TO BE CHANGED BEFORE RUNNING OUT THE DOOR AT 6 AM. FOR THIS AFTERNOON...BIG CHANGE TO THE FORECAST WAS TO BOOST HIGHS A FEW DEGREES...MAINLY OVER MN. BASED ON THE HOPWRF...ALONG WITH THE RAP...EXPECT SKIES TO OPEN UP PRETTY GOOD BY THIS AFTERNOON BEHIND THIS MORNINGS ACTIVITY. WITH H85 TEMPS IN THE NEIGHBORHOOD OF 16C...THIS WOULD FAVOR MIXING DOWN HIGHS INTO THE LOW TO MID 80S ACROSS MN. HELD HIGHS IN THE 70S ACROSS WI WHERE CLOUD COVER WILL BE MORE PERSISTENT. OF COURSE IF THE CLOUDS DO NOT CLEAR OUT AS PLANNED...THEN IT WILL BE A SECOND DAY IN A ROW WHERE CLOUDS RESULT IN A FORECAST THAT IS A BIT OVERDONE ON THE HIGHS.... FOR THIS AFTERNOON...THAT AFOREMENTIONED DAKOTAS THROUGH WILL MEANDER OVER TO NEAR THE MN/WI BORDER. THE GFS DEVELOPS UP TO 1000 J/KG OF MLCAPE OUT AHEAD OF THIS BOUNDARY...WHICH MAY BE ENOUGH TO GENERATE SOME ISO/SCT STORMS. HOWEVER...BEHIND THIS MORNINGS WAVE...ALL MODELS SHOW SOME PRETTY EXTENSIVE DRYING AND SUBSIDENCE IN THE MID-LEVELS. NAM/RAP SOUNDINGS SHOW A DECENT SUBSIDENCE INVERSION DEVELOPING AROUND H7 AS WELL. ALL OF THIS POINTS TO WHAT SHOULD BE A DRY DAY...THOUGH WITH INSTABILITY FORECAST TO BE IN PLACE...CAN NOT COMPLETELY RULE OUT SOME DIURNALLY DRIVEN THUNDERSTORM ACTIVITY DEVELOPING...SO HAVE LEFT SOME 20-30 POPS IN PLACE THIS AFTERNOON FOR ERN MN INTO WRN WI. FOR TONIGHT...THE MPX AREA LOOKS TO BE CAUGHT BETWEEN AREAS OF FORCING FOR PRECIP...WITH CURRENT PRECIPITATION HEADING FOR MICHIGAN AND THE FRONT FOR TUESDAY AFTERNOON REMAINING FAR ENOUGH NW TO KEEP THE AREA DRY. AT THE MOMENT...EXPECT MAINLY CLEAR SKIES TONIGHT...WITH LIGHT AND VARIABLE WINDS. WITH DEWPS UP IN THE UPPER 50S TO MID 60S...THIS COULD LEAD TO SOME POCKETS OF FOG DEVELOPING OVERNIGHT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 330 AM CDT MON AUG 5 2013 THE MAIN FORECAST CONCERN DURING THE TUESDAY THROUGH SUNDAY PERIOD WILL BE THE CHANCES FOR SHRA/TSRA TUESDAY AFTERNOON INTO TUESDAY NIGHT AS A COLD FRONT MOVES THROUGH THE REGION. THE REMAINS SOME VARIABILITY IN THE TIMING AND ORIENTATION OF THE FRONT AMONGST THE GFS... NAM... ECMWF... AND SREF... WITH THE NAM BEING FASTEST AND ECMWF BEING SLOWEST. A SHORTWAVE ROTATING EAST FROM THE NORTHERN ROCKIES WILL HELP DRIVE THE FRONT ACROSS THE AREA WHILE THE MAIN UPPER TROUGH DROPS SOUTH FROM CANADA. LARGE SCALE FORCING IN TERMS OF UPPER DIVERGENCE AND DPVA LOOK SUFFICIENT FOR FAIRLY WIDESPREAD PCPN TO OCCUR ALONG/AHEAD OF THE FRONT... WITH THALER QG DIAGNOSTICS DEPICTING AN ELONGATED AREA OF GOOD 700MB OMEGA FROM WESTERN LAKE SUPERIOR INTO NORTHWEST IOWA BY 00Z WEDNESDAY. THIS SHOULD BE MORE THAN SUFFICIENT TO GET SHRA/TSRA GOING DURING THE AFTERNOON HOURS AS THE FRONT MOVES THROUGH THE AREA. THE QUESTION THEN BECOMES WHETHER OR NOT ANY SEVERE WEATHER CAN BE EXPECTED. THE NEW DAY 2 OUTLOOK FROM SPC DOES INCLUDE A SLIGHT RISK ACROSS MOST OF THE AREA... ESSENTIALLY NEAR AND SOUTH OF I-94. IT LOOKS LIKE WE/LL HAVE ANYWHERE FROM 1000-2000 J/KG OF MLCAPE WITH WHICH TO WORK... ALONG WITH DEEP LAYER SHEAR AOA 40 KT... SO SOME ORGANIZED CONVECTION IS CERTAINLY POSSIBLE. DEEP LAYER SHEAR WILL BE SUFFICIENT FOR SUPERCELLS... BUT WOULDN/T EXPECT THE MODE TO REMAIN DISCRETE FOR VERY LONG GIVEN THE EXPECTATION FOR SOMEWHAT WIDESPREAD DEVELOPMENT. SO... CURRENT EXPECTATIONS WOULD BE FOR INITIAL SUPERCELLS TO QUICKLY TRANSITION INTO CLUSTERS AND A LINEAR SYSTEM WITH TIME. LOW LEVEL SHEAR DOESN/T LOOK TO BE TOO SIGNIFICANT... LIKELY AOB 15-20KT... WHICH SHOULD KEEP TORNADOES FROM BEING MUCH OF A THREAT... LEAVING LARGE HAIL AND WIND AS THE MAIN POTENTIAL ISSUES. THE FRONT SHOULD PUSH THROUGH THE REMAINDER OF THE FORECAST AREA TUESDAY NIGHT... WITH DRY WEATHER AND COOLER TEMPERATURES ON WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE AREA. THE NEXT CHANCE FOR PCPN LOOKS TO HOLD OFF UNTIL THURSDAY AFTERNOON AND THURSDAY NIGHT... WHEN THE MAIN UPPER LOW OVER CENTRAL CANADA DROPS SOUTH TOWARD THE INTERNATIONAL BORDER AND ANOTHER COLD FRONT PUSHES ACROSS THE REGION. MOISTURE RETURN WILL BE LIMITED AHEAD OF THE FRONT... BUT WILL BE SUFFICIENT GIVEN DECENT FORCING FOR SOME SHRA/TSRA. KEPT THINGS MAINLY DRY FROM FRIDAY THROUGH SUNDAY WITH THE EXPECTATION THAT AN EXPANSIVE HIGH WILL BUILD IN FROM CANADA. HOWEVER... IT SHOULD BE NOTED THAT THE 00Z ECMWF IS MORE PROGRESSIVE THAN THE GFS WITH THE UPPER PATTERN AND MANAGES TO FLATTEN THE FLOW OVER THE NORTH CENTRAL CONUS AND BRINGS A SURFACE LOW ACROSS MINNESOTA ON SUNDAY WITH DECENT FRONTOGENESIS AND AN ACCOMPANYING SLUG OF PCPN. STUCK CLOSER TO THE PREVIOUS FORECAST AND GFS AT THIS POINT... AND JUST INCLUDED SOME CHANCE POPS OVER THE SOUTHWEST PORTION OF THE CWFA ON SUNDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 110 AM CDT MON AUG 5 2013 THUNDERSTORM COMPLEX OVER MN NOW IS MAIN CONCERN FOR THESE TAFS. BIG THING TO NOTE ABOUT THIS COMPLEX IS BASED ON CURRENT TRENDS...NOTHING IS FAST ENOUGH WITH HANDLING THIS COMPLEX. BASED ON HOW THINGS ARE LINING UP ON RADAR...PREFER A 00Z HOPWRF IDEA WITH PRIMARY AXIS OF PRECIPITATION ALIGNING FAIRLY CLOSELY TO THE MN RIVER VALLEY FROM WC MN INTO SE MN/NE IA. FOR TIMING...STUCK CLOSE TO THE IDEA OF THE HOPWRF MEMBERS...JUST SPED THEM UP A COUPLE OF HOURS. THAT GETS THUNDER OUT OF AXN WITHIN THE HOUR...THROUGH MSP BY AROUND 10Z AND OUT OF THE EAU AREA SHORTLY AFTER 12Z. AS THESE SHOWERS MOVE THROUGH...WILL HAVE TO WATCH FOR THE DEVELOPMENT OF MVFR OR LOWER CIGS THAT COULD PLAGUE SITES MUCH OF THE MORNING. FOR THE AFTERNOON...EXPECT SKIES TO SCT OUT. BASED ANY AFTERNOON THUNDER POTENTIAL ON THE GFS...WHICH CONFINES INSTABILITY TO WRN WI THIS AFTERNOON. WILL BE A BOUNDARY WORKING INTO THERE AS WELL...WHICH SUPPORTS THE IDEA OF SOME SCT TSRA DEVELOPING IN THE EAST THIS AFTERNOON. FOR TONIGHT...SKIES SHOULD GO MOSTLY CLEAR WITH WINDS GOING LGT AND VRB. KMSP...BASED SHRA/TSRA TIMING MORE ON CURRENT TRENDS THEN ANY BIT OF GUIDANCE...AS ALL GUIDANCE IS BEHIND THE CURVE IN TERMS OF TIMING OF CURRENT ACTIVITY. HEAVIEST PRECIP STILL LOOKS TO BE GOING SOUTH OF THE FIELD...THOUGH STILL LOOKS GOOD FOR AN UP TO 2 HOUR PERIOD OF SHRA/TSRA BETWEEN MAINLY 8Z AND 10Z. DO EXPECT CIGS TO DEVELOP BEHIND THE RAIN...BUT STILL LOTS OF QUESTIONS AS TO HOW LOW THEY WILL BE. CURRENTLY IN SW MN/SE SD CIGS ARE MAINLY CHECKING IN AT 3K TO 4K FT...SO CURRENT TAF MAY BE OVERDONE. CONFIDENCE IS HIGH IN THE REST OF THE TAF BEING DRY...WITH ANY SCT ACTIVITY THIS AFTERNOON ENDING UP EAST OF THE FIELD. /OUTLOOK FOR KMSP/ TUE...TSRA LIKELY AFTERNOON/EVENING. VFR OUTSIDE OF TSRA. WINDS WSW 5-10KTS...BCMG NW OVERNIGHT. WED...VFR. WINDS NW 10 KTS. THU...VFR. CHC TSRA OVERNIGHT. WINDS SW 5 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...MPG
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
341 AM CDT MON AUG 5 2013 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 335 AM CDT MON AUG 5 2013 THE LARGE SCALE FLOW REGIME HAS CHANGED LITTLE OVER THE LAST 24 HOURS WITH A VORTEX OVER HUDSON BAY AND UPPER HIGH CENTERED IN WEST TX AND NW FLOW ALOFT THROUGH THE NATIONS MIDSECTION. WEAK DISTURBANCES ALOFT CONTINUE TO TRACK FROM THE CENTRAL ROCKIES ESEWD THRU KS WITHIN THE FLOW ALOFT. CLUSTERS OF THUNDERSTORMS ACROSS SE KS AND SW MO EARLY THIS MORNING ARE OCCURING TO THE NORTH OF A QUASI- STATIONARY BOUNDARY DRAPPED FROM THE OK PANHANDLE INTO THE LOWER MS VALLEY AND IN ADVANCE OF ONE OF THESE WEAK DISTURBANCES...AND ARE STRONGLY DRIVEN BY A BROAD 30+ KT SWLY LLJ. MODEL CONSENSUS AND RECENT RUNS OF THE HRRR SUGGEST A FAMILIAR THEME TO RECENT MORNINGS...THE ACTIVITY WILL TRACK ESEWD THIS MORNING IN ADVANCE OF THE MIGRATING DISTURBANCE AND AS THE LLJ VEERS TO MORE WESTERLY. THIS SHOULD BRING THE GREATEST IMPACT OF THE WEAKENING SHOWERS AND THUNDERSTORMS TO THE EASTERN OZARKS THIS MORNING...WITH ANY RESIDUAL SHOWERS EXITING BY EARLY AFTERNOON. FORCING FOR ANY PRECIPITATION IS RATHER WEAK AND NON-FOCUSED ELSEWHERE AND WORTHY OF A MERE SLIGHT CHANCE. I THINK THERE WILL BE A SLIGHT NORTHWARD JOG IN THE MCS TRACK TONIGHT INTO TUESDAY AS THE BOUNDARY TO THE SOUTH LIFTS SLIGHTLY AND DISTURBANCES ALOFT TRACK A TAD FURTHER NORTH THAN THE LAST SEVERAL DAYS. PRESENT INDICATIONS ARE THAT THE ONE OR MORE MCSS WILL DEVELOP FROM SOUTH CENTRAL KS INTO SOUTH CENTRAL MO AS THE SWLY LLJ RAMPS UP THIS EVENING AND THEN STRENGTHENS AND VEERS OVERNIGHT. THIS ACTIVITY WILL BE ONGOING WITHIN THIS CORRIDOR AT DAYBREAK TUESDAY AND SHIFTING TO THE ESE DURING THE DAY IN ADVANCE OF THE MIGRATING DISTURBANCE ALOFT AND AS THE LLJ CONTINUES TO VEER. THE HIGHEST POPS WILL BE CONCENTRATED ALONG AN AXIS JEFFERSON CITY TO FARMINGTON. GLASS .LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY) ISSUED AT 335 AM CDT MON AUG 5 2013 CONSENSUS OF THE ECMWF...SREF...AND NAM IS WE SHOULD SEE A SYNOPTIC SCALE COLD FRONT PUSH INTO NRN SECTIONS OF THE AREA LATE TUESDAY NIGHT AND PROGRESS SEWD DURING THE DAY ON WEDNESDAY. A BROAD SWLY LLJ OF 30+ KTS REMAINS FOCUSED AHEAD OF THE FRONT TUESDAY NIGHT AND SHOULD SUPPORT LIKELY PROBABILITIES OF SHOWERS AND THUNDERSTORMS WITH THAT THREAT SHIFTING SEWD AHEAD OF THE FRONT ON WEDNESDAY. THE UPPER FLOW REGIME WILL CHANGE SLIGHTLY WEDNESDAY THROUGH FRIDAY WITH A MORE ZONAL COMPONENT WHILE THE FRONT BECOMES QUASI-STATIONARY FROM THE TN VALLEY ACROSS ARKANSAS INTO NORTHERN OK. THIS MORE ZONAL COMPONENT IN THE FLOW ALOFT WILL BRING THE DISTURBANCE TRACK WEST TO EAST MORE THROUGH THE MID MS VALLEY AND MODULATE THE S/SWLY LLJ...TO BRING A CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS TO THE SOUTHERN 2/3RDS OF THE CWA AT LEAST INTO FRIDAY. GLASS && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1131 PM CDT SUN AUG 4 2013 EXPECTING VFR CONDITIONS TO CONTINUE TO PREVAIL ACROSS MUCH OF THE AREA...WITH THE EXCEPTIONS OF PARTS OF CENTRAL AND NORTHEAST MISSOURI AS WELL AS A SMALL PART OF WEST CENTRAL ILLINOIS. A SMALL PART OF SOUTHEAST MISSOURI...PROBABLY SOUTH OF FARMINGTON...WILL LIKELY SEE LOWERED CEILINGS AS WELL AS LOWERED VISIBILITY IN RAIN AND POSSIBLY THUNDERSTORMS LATER TONIGHT. CIGS BELOW 2000FT...AND POSSIBLY BELOW 1000FT LOOK LIKELY ACROSS CENTRAL MISSOURI AND THAT SMALL PORTION OF SOUTHEAST MISSOURI. A COMPLEX OF THUNDERSTORMS IS ALREADY MOVING INTO SOUTHWEST MISSOURI FROM KANSAS...AND DEBRIS FROM THESE STORMS WILL BE THE PRIMARY CAUSE OF THE MVFR CIGS LATER TONIGHT. THINK MOST OF THE PRECIP SHOULD STAY IN SOUTHWEST/SOUTH CENTRAL MISSOURI THOUGH. CEILINGS SHOULD RISE BACK TO VFR RANGE BY 18Z MONDAY. SPECIFICS FOR KSTL... EXPECT VFR FLIGHT CONDITIONS AND LIGHT SOUTHEAST-SOUTH SOUTHEAST FLOW TO CONTINUE TONIGHT. A COMPLEX OF THUNDERSTORMS WILL PASS WELL TO THE SOUTHWEST OF THE TERMINAL THROUGH THE NIGHT INTO MONDAY MORNING. DEBRIS CLOUDS FROM THESE STORMS WILL LIKELY CAUSE CIGS TO FALL TO LOW VFR RANGE DURING THE MORNING. THERE IS STILL SOME POSSIBILITY THAT CIGS COULD FALL BELOW 3000FT...BUT LATEST MODEL GUIDANCE HAS BEEN TRENDING HIGHER. VFR CONDITIONS ARE EXPECTED TO CONTINUE MONDAY INTO MONDAY NIGHT. CARNEY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1204 AM CDT Mon Aug 5 2013 .SHORT TERM...(This Evening through Monday Night) Issued at 406 PM CDT SUN AUG 4 2013 Tonight...12Z operational models, especially the NAM, had difficulty evaluating the mesoscale features from last nights/todays MCS with double MCV...mesoscale vorticity center...structure. As one would expect the short range HRRR did a much better job with this system. The trailing MCV now moving into southeastern KS is aiding downstream scattered areas of rain from the southern CWA southward across southern MO. The latest HRRR maintains this area of precipitation through mid evening and then steadily diminishes it. Will follow this trend for the evening hours. Thunder chances look minimal owing to less than stellar instability due to the rain-cooled airmass and extensive cloud shield. Looking upstream within the monsoonal flow circulating around the Southern Plains upper high yields little if any clues for the next shortwave or disturbance aloft which could generate new convection. However, believe convection for the overnight hours lies with the increasing southwesterly low level jet that is expected to form from the Southern Plains into KS. GFS and NAM output both signal increasing moisture convergence and isentropic ascent will likely generate another convective complex. Due to the subsidence left behind from todays MCS and the models poor handling of this feature have some question as to where this convection will form. For now will place my bet on southeastern KS with the activity spreading into and across mainly the southern CWA. In addition to the rain tonight am expecting to see MVFR type fog form. Monday-Monday night...Models show no discernible disturbances embedded with the northwest flow which will affect the CWA during the daylight hours. So, rain chances are most likely tied to the morning hours and across the far southern counties where the combo of isentropic lift and a weakening low level jet aid a departing MCS. Have backed off on high temperatures by a handful of degrees as warm front not likely to move into the CWA and amount of residual cloud cover will impact surface heating. The nocturnal low-level jet is expected to reform Monday night and enhance the lift along/north of the surface front which is expected to lift northward across central/eastern KS and west central MO later in the evening. Have moderate confidence this will generate some healthy convection and will increase PoPs after midnight for the western counties. .LONG TERM...(Tuesday through Sunday) Issued at 406 PM CDT SUN AUG 4 2013 Slight northwest to almost zonal type flow regime will continue across the central US as the Hudson Bay vortex across southern Canada will deepen as it slowly progresses towards southern Ontario and the northern Great Lakes region. A shortwave trough will rotate along the periphery of this system and help to push a cold front southeastward through the Central Plains. This front will near the area by Tuesday night and will be the focus for convective development Tuesday night into Wednesday morning. The expected MCS will initially develop north of the CWA, along the front, during the afternoon and gradually make its way into the CWA as the evening progresses. The remainder of the week will see spotty precipitation chances as the Hudson Bay low gradually moves eastward and ridging remains positioned across the Rockies. A few shortwave troughs may ride the ridge and help to initiate convection across the region. Temperatures will be slightly cooler behind this front as surface high slides into the region, but will gradually warm into the mid 80s as we near the weekend. && .AVIATION...(For the 06Z TAFS through 06Z Monday Night) Issued at 1153 PM CDT SUN AUG 4 2013 Low MVFR to IFR conditions are expected to dominate the morning hours of Monday. Have left IFR conditions in through noon as there is an expectation that early morning storms to the south will be very slow to clear. Have left any mention of convection out of the terminals at this time owing to very low confidence that any storms will move that far north from the main axis of activity which has set up across southeast Kansas. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...MJ LONG TERM...PMM AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
352 AM CDT MON AUG 5 2013 .DISCUSSION... SHORT TERM CONCERNS WILL BE LOW CLOUDS AND FOG THIS MORNING AND POTENTIAL FOR ISOLATED SHOWERS AND THUNDERSTORMS TODAY IN THE NORTH ...THEN ATTENTION TURNS TOTUESDAY CONVECTIVE POTENTIAL. WATER VAPOR SATELLITE IMAGERY AND LIGHTNING DATA SHOW MOISTURE STREAMING NORTHWARD ACROSS MEXICO INTO THE FOUR CORNERS REGION INTO THE PLAINS AND THEN SOUTHEAST TOWARD THE LOWER MISSISSIPPI VALLEY... ANTI-CYCLONICALLY AROUND THE LARGE AREA OF H5 HIGH PRESSURE CENTERED OVER NEW MEXICO AND WEST TEXAS. MEANWHILE...CONVECTION WAS ALSO MOVING INTO THE PACIFIC NORTHWEST AND ACROSS THE NORTHERN PLAINS...WHERE THE STRONGER H3 JET RESIDED. THERE WERE 10 TO 20 METER HEIGHT FALLS ASSOCIATED WITH SHORTWAVE TROFS OVER NORTH DAKOTA AND ALSO NEAR SPRINGFIELD MISSOURI. THERE WAS ABUNDANT MOISTURE OVER THE PLAINS WITH MOST LOCATION ON THE PWAT CHART BETWEEN 100-160% OF NORMAL. WIDESPREAD H85 DEWPOINTS OF +12 TO +16C...WITH A MAX OF +18C AT DDC. H7 DEWPOINTS WERE +9 DEG C AT DDC AND +6 AT TOP. H7 TEMPERATURES HAD WARMED INTO THE +10 TO +14 C RANGE FOR MUCH OF THE PLAINS...WITH THE COOLER TEMPS TOWARD ABR...TOP/SPRINGFIELD. THERE WERE TWO THERMAL RIDGES AT H85...ONE WAS NOSING INTO THE NEBRASKA PANHANDLE AND THE OTHER WAS NOSING INTO THE TEXAS PANHANDLE AND OKLAHOMA. THE LATEST WSR-88D RADAR MOSAIC SHOWED THREE CONVECTIVE COMPLEXES....ONE ACROSS MN/NRN IA...ONE OVER SOUTHEAST KANSAS AND ONE OVER WESTERN SOUTH DAKOTA. AFTER SOME MORNING CLOUDS AND FOG...A STRONG SHORTWAVE TROF OVER NORTH DAKOTA WILL CONTINUE TO PUSH SOUTHEAST TODAY AND WILL DRAG A FRONT INTO NORTHEAST NEBRASKA. THE BULK OF THE CONVECTIVE ACTIVITY SHOULD REMAIN TO OUR NORTH AND EAST...LIMITED BY THE WARM MID LEVEL TEMPERATURES LOCALLY...HOWEVER ISOLATED ELEVATED THUNDERSTORMS COULD MAKE IT INTO NORTHEAST NEBRASKA AND WEST CENTRAL IOWA. THERE IS STRONG DEEP LAYER SHEAR OF 50KTS...SO STORMS WILL NEED TO BE WATCHED NEAR THE SD/NEB BORDER. MOST OF THE SHORT RANGE MODELS LIMIT THE SOUTHWARD PROGRESS DURING THE DAY...HOWEVER THE LATEST RAP IS MORE AGGRESSIVE WITH PRECIPITATION MAKING IT FARTHER SOUTH...SO THIS WILL NEED TO BE WATCHED. WARMER H85 TEMPS ARE EXPECTED AND HAVE HIGHS IN THE 80S ALTHOUGH IF CLOUDS HANG ON...THIS COULD KEEP THE HIGHS A LITTLE LOWER. MONDAY NIGHT...AN MCS IS FORECAST TO DEVELOP OVER THE NORTHERN PLAINS AND SPREAD SOUTHEAST. THIS SYSTEM HAS DECENT INSTABILITY OF 3-4000J/KG AND DEEP LAYER SHEAR OF 45-53KTS THUS STORMS COULD BE SEVERE. THE MODELS HAVE A VARIETY OF SOLUTIONS ON THE PLACEMENT OF THE BEST PRECIP...HOWEVER WILL MAINTAIN HIGH POPS WITH THE FRONT TUESDAY INTO TUESDAY EVENING. POOLING OF MOISTURE ALONG THE FRONT COULD RESULT IN LOCALLY HEAVY RAINS. DRYING ENSUES WITH SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTH SHOULD SHUT DOWN THE PRECIPITATION TUESDAY NIGHT AND WEDNESDAY. HIGHS WEDNESDAY SHOULD BE COOLER...IN THE 70S TO LOWER 80S. RETURN FLOW SETS UP WEDNESDAY NIGHT AND COULD SEE SOME STORMS RETURN ESPECIALLY SOUTHWEST. THE EXTENDED THURSDAY THROUGH SUNDAY. H5 LOW PRESSURE OVER HUDSON BAY WILL SLOWLY MOVE EAST WITH BUILDING HEIGHTS OVER THE ROCKIES AND NORTHWEST FLOW ALOFT FOR THE FORECAST AREA. DEEP MOISTURE WILL REMAIN IN PLACE...ESPECIALLY FOR THE SOUTHERN PART OF THE FORECAST AREA AND THIS IS WHERE THERE WOULD BE A HIGHER RISK OF THUNDERSTORMS. SHORTWAVES IN THE NORTHWEST FLOW ALOFT AND STORMS THAT FORM IN THE WESTERN HIGH PLAINS COULD ROLL EAST FRIDAY NIGHT INTO SUNDAY NIGHT...ALTHOUGH THE EASTERLY LOW LEVEL FLOW OFF THE SURFACE HIGH COULD LIMIT COVERAGE. THERE ARE DECENT MODEL DIFFERENCES BY SUNDAY AS TO WHERE THE FRONTAL SYSTEMS WILL BE THUS HAVE LEFT IN THE CHC POPS. HIGHS WILL CONTINUE TO BE AT OR BELOW NORMAL. && .AVIATION... 06Z TAFS FOR KOMA...KLNK...KOFK. STILL EXPECT DETERIORATING CONDITIONS OVERNIGHT. MVFR CEILINGS HAVE SET IN ACROSS MUCH OF SOUTHEAST AND EAST CENTRAL NEBRASKA AND SHOULD MOVE INTO NORTHEAST NEBRASKA THE NEXT FEW HOURS. IFR CONDITIONS SHOULD AT LEAST TEMPORARILY AFFECT ALL THREE SITES MAINLY BETWEEN 09Z AND 13Z. CONDITIONS SHOULD IMPROVE INTO THE VFR CATEGORY BY MID TO LATE MONDAY MORNING. DID NOT MENTION ANY PCPN AT THIS TIME...BUT SOME ISOLD SHRA OR TSRA COULD DEVELOP MONDAY AFTERNOON. MILLER && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ ZAPOTOCNY
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1227 AM CDT MON AUG 5 2013 .SYNOPSIS... LITTLE CHANGE TO THE OVERALL PATTERN IN THE LAST 24 HOURS. UPPER LEVEL RIDGE REMAINS CENTERED OVER NW TX. SEVERAL SHORT WAVES RIDING AROUND THE PERIPHERY OF THE RIDGE...WITH GOOD TAP TO TROPICAL MOISTURE. AT THE SFC SOUTHEASTER FLOW CONTINUES TO PUMP MOISTURE INTO THE REGION. DEW PTS HAVE CREPT UP INTO THE MID 60S...WITH LOWER 70S ACROSS MUCH OF KANSAS. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 345 PM CDT SUN AUG 4 2013 TONIGHT...THE NEXT SHORT WAVE RIDING ACROSS THE CENTRAL ROCKIES WILL BE THE FOCUS FOR CONVECTION ALONG THE FRONT RANGE. SOME UNCERTAINTY TO THE SUSTAINABILITY FOR THE STORMS AS THEY MOVE OFF THE HIGHER TERRAIN. THE HRRR SUGGESTS THE STORMS WILL MAKE IT INTO WESTERN NEBRASKA...WHILE THE NAM/RUC FAVOR NORTHERN NEB...UTILIZED THE BLACK HILLS FOR INITIATION. THE NOSE OF THE LL JET OVERNIGHT FOCUSES NEAR THE NEB/S DAKOTA BORDER AND WILL FAVOR THE NORTHERN ZONES WITH THE HIGHEST POPS. LOW LEVEL MOISTURE REMAINS EXCELLENT AND GUIDANCE IN AGREEMENT WITH LOW CLOUDS TO CONTINUE/REDEVELOP ACROSS THE AREA OVERNIGHT. COULD SEE SOME FOG ACROSS SW NEB AS DEW POINTS ARE UP A FEW DEGREES FROM THE PAST COUPLE OF DAYS AND EXPECT TO EASILY SEE 100 PERCENT RH AS TEMPS COOL INTO THE LOWER TO MID 60S...HOWEVER THE LATEST MOS GUIDANCE HOLD VSBY IN THE 4 TO 6 MILE RANGE AND FORECAST FAVORS THE LOW STRATUS WITH POCKETS OF FOG. NOT EXPECTING FOG TO BE WIDESPREAD ENOUGH AT THIS TIME TO INCLUDE IN FORECAST...HOWEVER WILL MONITOR. MONDAY...LINGERING THUNDERSHOWERS ACROSS NORTH CENTRAL NEBRASKA SHOULD DECAY IN THE MORNING WHILE STRATUS ELSEWHERE WILL BE SLOW TO ERODE. ANOTHER SHORT WAVE...A STRONGER SYSTEM...WILL ENTER THE REGION FOR THE AFTERNOON. AS THE CLOUDS FINALLY BEGIN TO BREAK AND TEMPS QUICKLY BUMP INTO THE 80S WITH A FEW LOWER 90S ACROSS THE SW...GROWING INSTABILITY SHOULD BE ENOUGH FOR CONVECTION. SPC HAS A SLIGHT RISK IN PLACE FOR WESTERN NEBRASKA AND AGREE WITH 40 TO 50 KTS OF SHEAR WITH DEW PTS IN THE 60S. THUNDERSTORMS SHOULD BREAK THE CAP IN THE AFTERNOON. PRECIPITABLE WATER AROUND 130 TO 150 PERCENT OF NORMAL SHOULD BE SUFFICIENT FOR LOCALLY HEAVY RAINFALL. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 345 PM CDT SUN AUG 4 2013 MONDAY NIGHT THROUGH WEDNESDAY...DESPITE THE DEEP MOISTURE...THE MODELS ARE BACKING OFF ON ANY SORT OF WIDESPREAD HP EVENT LATE MONDAY. IT MAY BE THAT THE CAP IS VERY STRONG IN THE LATEST SOLNS SHOWING A STRENGTHENING CAP OF 12C TO 14C AT 700 MB ACROSS WRN NEB AND THE UPPER LEVEL FORCING IS WEAK MONDAY. MODEL BLENDED POPS ARE AROUND 30 PERCENT AND QPF IS LESS THAN 1/10 OF AN INCH FOR MONDAY NIGHT. ON TUESDAY A COLD FRONT WILL DROP THROUGH THE FCST AREA PROVIDING FOCUS FOR STORM DEVELOPMENT. THE 00Z WEDNESDAY MODEL CONSENSUS SHOWS THE SFC LOW ACROSS SWRN KS WHICH IS A POST FRONTAL ENVIRONMENT FOR POPS ACROSS THE FCST AREA. THE GEM...GFS AND ECM ARE KEYING ON MOISTURE TRAPPED BEHIND THE COLD FRONT ACROSS ERN PTNS OF NCNTL NEB WHERE THE CAP WILL BE WEAKEST. POPS ARE 40 PERCENT THERE IN THE AFTN BUT FALL OFF TUESDAY EVENING AS A MCS DROPS SOUTH THRU CNTL AND ERN NEB. ALL MODELS SHOW A 12C-14C CAP ACROSS SWRN NEB TUESDAY WHICH IS LIKELY LIMITING CONVECTION. THIS THERMAL RIDGE WILL DROP SOUTH LATE TUESDAY AFTN WHICH COULD OPEN UP THE FCST AREA TO MORE WIDESPREAD CONVECTION THAN INDICATED BY THE MODELS. THE FRONT WILL DROP SOUTH ON THE HEALS OF A 300 MB JET IN COMBINATION WITH A DEEP UPPER LEVEL LOW DROPPING THROUGH MANITOBA. THIS PRODUCES 45 TO 55 KT OF 0-6KM BULK SHEAR TUESDAY AFTN WITH ML CAPE OVER 3000J/KG EAST OF HIGHWAY 83. THE SHEAR AND CAPE VALUES ARE MUCH WEAKER MONDAY EVENING SO THE BEST CHANCE FOR SEVERE WEATHER IS TUESDAY ALONG AND EAST OF HIGHWAY 83. THE DEEP UPPER LEVEL CYCLONE DROPPING THRU MANITOBA WILL PUSH A STRONG COLD FRONT THROUGH THE FCST AREA WEDNESDAY AND HIGH TEMPS WILL STRUGGLE TO REACH 80F. HIGHS TUESDAY RISE INTO THE LOWER 90S SOUTH WITH THE THERMAL RIDGE OVERHEAD. 80S ARE EXPECTED ELSEWHERE. ANY CONVECTION THAT FIRES SHOULD BE MOSTLY SOUTH AND WEST OF THE FCST AREA. THERE IS A GLITCH IN THE FORECAST THOUGH. THE 18Z NAM IS LIFTING A SUBTROPICAL SHORT WAVE THROUGH SWRN NEB WEDNESDAY AFTN. THE GEM...ECM AND GFS MOVE THIS WAVE THROUGH KS SOUTH OF THE FCST AREA. FOR THE FCST USES THE CONSENSUS WHICH IS FOR ISOLATED STORMS ACROSS THE SOUTH WEDNESDAY. WEDNESDAY NIGHT THROUGH SUNDAY...A NEW DEVELOPMENT IN THE 12Z MODEL RUNS IS THEY ARE NOT NEARLY AS STRONG WITH A REINFORCING COLD FRONT THAT WAS FCST TO PULL VERY COOL AIR SOUTH OUT OF CANADA. THE GFS ENSEMBLE HOLDS THE HIGH ACROSS MANITOBA AND SASKATCHEWAN WITH A STATIONARY FRONT DRAPED ACROSS THE CNTL PLAINS. IN FACT THE FCST AREA REMAINS UNDER SOUTH AND SOUTHEAST WINDS AT 850 MB. NOW THE ALLBLEND TOTAL QPF FOR THIS PERIOD SHOWS AROUND 1 INCH ACROSS SCNTL NEB TO LESS THAN 1/4 OF AN INCH ACROSS WRN/NRN NEB SUGGESTING A STATIONARY FRONT WILL OPERATE ACROSS THE FCST AREA. POPS ARE STILL ISOLATED TO SCATTERED AND TEMPS ARE A BIT WARMER...UPPER 70S TO LOWER 80S. IT WOULD APPEAR THAT THE SOUTHERLY WINDS ARE BACKED AROUND THE MANITOBA HIGH. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1227 AM CDT MON AUG 5 2013 ISOLATED THUNDERSTORMS WILL CONTINUE TO MOVE TO THE EAST OVER THE NEBRASKA SANDHILLS. HAVE INCLUDED A VCTS FOR KLBF TAF SITE WITH TRAJECTORY OF STORM EXPECTED TO PASS TO THE NORTH OF THE SITE. MVFR TO IFR CIGS WILL DEVELOP AGAIN TONIGHT AFTER 0509Z. CIGS WILL LIFT THROUGH THE MORNING. SHOWERS POSSIBLE OVER NORTHERN NEBRASKA AROUND SUNRISE AND THUNDERSTORMS OVER SOUTHERN NEBRASKA MONDAY AFTERNOON. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MASEK LONG TERM...CDC AVIATION...SPRINGER
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1127 PM MDT SUN AUG 4 2013 .AVIATION... 06Z TAF CYCLE SHRA AND A FEW TSRA WILL CONTINUE ACROSS THE NORTHERN MTS THRU APPROX 10Z. MT TOPS MAY BE OCCASIONALLY OBSCURED. ELSEWHERE... OUTFLOW BOUNDARIES WILL CONTINUE TO INITIATE NEW STORMS FROM ABQ TO ONM AND EASTWARD TO CQC. THESE STORMS MAY MOVE INTO LVS BUT CONFIDENCE IS LOW ATTM. BRIEF HVY RAIN WILL LOCALLY REDUCE VSBY DOWN TO 4SM. MUCH OF THIS ACTIVITY WILL DIMINISH BY SUNRISE...THOUGH A FEW STORMS MAY DEVELOP OVER THE SW MTNS AROUND THIS TIME. ANOTHER ROUND OF SHRA AND TSRA WILL DEVELOP OVER THE HIGH TERRAIN AND NE NM BY LATE MORNING/EARLY AFTN. OUTFLOW BOUNDARY COLLISIONS WILL AGAIN HELP DEVELOP STORMS ACROSS THE LOWER ELEVATIONS BY LATE AFTN. LOCALLY HVY RAIN...SMALL HAIL AND GUSTY WINDS WILL BE THE MAIN THREATS. 34 && .PREV DISCUSSION...216 PM MDT SUN AUG 4 2013... ...INCREASED POTENTIAL FOR LOCALLY HEAVY RAINFALL THROUGH TONIGHT... RADAR TRENDS INDICATING SCATTERED TO NUMEROUS STORMS ACROSS THE HIGH TERRAIN OF CENTRAL NM. 19Z LAPS ANALYSIS SHOWS A SIGNIFICANT AMOUNT OF MOIST INSTABILITY OVER THE AREA WITH 2000-3500J/KG CAPE AND LIFTED INDICES BTWN -3 AND -6C FROM THE RGV INTO THE NE PLAINS. 700-500MB STORM MOTION VECTORS ARE NORTH NEAR 5 KTS WHICH IS MUCH SLOWER THAN YESTERDAY...SO THE HEAVY RAINFALL THREAT IS HIGHER AS WELL. PLACED MENTION OF LCL HEAVY RAIN IN GRIDS BUT WILL NOT ISSUE A FLASH FLOOD WATCH. OUTFLOW BOUNDARIES WILL ACTIVATE IN THIS REGIME TO PRODUCE MORE STORMS FOR VALLEY AREAS LATER IN THE DAY AS SHOWN BY THE RUC AND HRRR GUIDANCE. A LARGE PRECIP SHIELD IS LIKELY TO MOVE SLOWLY NORTH OVER CENTRAL NM AS WELL TONIGHT. RAISED POPS CONSIDERABLY FOR THIS REGION. MONDAY WILL BE AN ACTIVE DAY AGAIN. THE GFS INDICATES PWAT VALUES WILL TREND DOWN JUST SLIGHTLY AND THE MAIN AXIS OF INSTABILITY WILL SHIFT A LITTLE EAST ONTO THE HIGH PLAINS. STORM MOTIONS WILL BE MORE SOUTHWESTERLY AND SLOW AGAIN. THIS WILL BRING A LITTLE MORE COVERAGE TO THE EASTERN PLAINS DURING THE EVENING. WESTERN NM WILL STILL SEE VERY WEAK STORM MOTIONS WITH LCL HEAVY RAINFALL. TUESDAY IS EXPECTED TO BE ACTIVE AS WELL. AN EASTERLY WAVE NOTED ON WATER VAPOR ALONG THE WEST CENTRAL MEXICAN COAST WILL SHIFT NORTH AND IMPACT EASTERN AZ/WESTERN NM. RAISED POPS FOR TUESDAY. STEERING FLOW WILL INCREASE MORE BUT STILL REMAIN LIGHT ENOUGH FOR HEAVY RAINERS. DRIER MORE STABLE AIR WILL WORK INTO WESTERN/CENTRAL NM BEHIND THE UPPER WAVE. STORM COVERAGE WILL DIMINISH CONSIDERABLY FOR THE WEST. THIS UPPER WAVE WILL BECOME CAUGHT UP IN NORTHWEST FLOW OVER THE CENTRAL PLAINS STATES AND ENHANCE A SURFACE BACK DOOR FRONTAL BOUNDARY OVER NORTHEAST NM. THE NAM IS BULLISH WITH THE STRENGTH OF THIS SURFACE BOUNDARY AND THE COVERAGE OF STORMS. OVERALL THE PATTERN THROUGH THE REMAINDER OF THE WEEK LOOKS TO LOCK IN A VERY WELL DEFINED MONSOONAL CIRCULATION OVER CENTRAL/WESTERN NM. GUYER .FIRE WEATHER... UPPER HIGH ANCHORED OVER CENTRAL TEXAS WILL SLOWLY SHIFT TOWARD THE EAST AND SOUTH THROUGH LATE TUESDAY...BECOMING ELONGATED NEAR THE TX GULF COAST REGION BY WEDNESDAY MORNING. WELL ADVERTISED UPTICK IN THUNDERSTORM COVERAGE FOR THIS AFTERNOON HAS PANNED OUT WELL WITH STORM MOTIONS GENERALLY TOWARD THE NORTH-NORTHEAST AT 15 MPH OR LESS. OUTFLOW BOUNDARY INTERACTIONS IN THE PRESENCE OF A MUCH MORE UNSTABLE ENVIRONMENT SHOULD RESULT IN QUITE A BIT MORE THUNDERSTORM ACTIVITY IN THE VALLEYS BY MID TO LATE AFTERNOON AND INTO THE EVENING AS COMPARED TO SATURDAY...WITH THE POTENTIAL FOR HEAVY THUNDERSTORM RAINS INCREASING AND EXPANDING ACROSS THE NORTHEAST. THE UPPER FLOW REGIME WILL FAVOR LATE NIGHT OR NOCTURNAL SHOWERS FOR AREAS BETWEEN THE CONTINENTAL DIVIDE AND CENTRAL MOUNTAIN CHAIN WITH THE CENTRAL VALLEY CORRIDOR ESPECIALLY FAVORED. WELL-ESTABLISHED MONSOON PLUME ALONG THE WESTERN PERIPHERY OF THE RIDGE WILL CHANGE VERY LITTLE OVER THE NEXT 24-36 HOURS. LINGERING CLOUD COVER MONDAY MORNING MAY LIMIT EARLY DAYTIME HEATING AND THUS TOMORROW/S CROP OF THUNDERSTORMS MAY NOT BE QUITE AS WIDESPREAD AS TODAY BUT THE PATTERN WILL REMAIN FAVORABLE FOR THE WESTERN TWO-THIRDS OF THE AREA. TUESDAY WILL MARK A TRANSITION TO A RELATIVELY FASTER SW TO NE STEERING FLOW...AND POSSIBLY AN ENHANCED WINDOW OF MOISTURE/DYNAMIC FORCING ASSOCIATED WITH AN EASTERLY WAVE THAT WILL SLOWLY APPROACH THE REGION IN THE CLOCKWISE FLOW AROUND THE HIGH. WHILE MODELS SHOW THIS FEATURE TRACKING NORTH-NORTHWEST WELL TO OUR SOUTHWEST...ITS REMNANTS SHOULD EVENTUALLY WORK BACK TOWARD THE EAST AND THE FOUR CORNERS. MEDIUM RANGE GUIDANCE SHOWING SOME NICE CONSISTENCY THUS FAR AND WE WILL SEE IF THE TREND CONTINUES. OVERALL LOW CONFIDENCE IN WHAT WILL BECOME OF THIS FEATURE...HOW FAR NORTH IT MAY TRACK BUT THE MODELS ARE GENERALLY IN DECENT AGREEMENT SHOWING THE WAVE TRANSLATING EASTWARD OVER SOUTHERN COLORADO AND NORTHERN NEW MEXICO WED-WED PM. AT THE SAME TIME...A GOOD LOOKING BACKDOOR COLD FRONT IS INDICATED TO SURGE SOUTHWARD SETTING UP A POTENTIALLY VERY ACTIVE PATTERN FOR AREAS EAST OF THE CENTRAL MOUNTAIN CHAIN AND ESPECIALLY THE NORTHEAST. EXTENT OF LOWER LEVEL DRYING ACROSS THE WEST REMAINS A BIG QUESTION MARK...AS MODELS ARE QUITE AGGRESSIVE IN DRYING DEW POINTS DURING THE WED/THU PERIOD. KJ && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
348 AM CDT MON AUG 5 2013 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 SURFACE TROUGH WILL CONTINUE TO PROPAGATE THROUGH THE FA. SCATTERED SHOWERS ACROSS THE EASTERN FA SHOULD BE EAST OF THE REGION BY 12Z. WEAK HIGH PRESSURE WILL MOVE INTO THE REGION. THE MAIN CHALLENGE FOR TODAY WILL BE CLOUDS AND ASSOCIATED TEMPERATURES. THERE IS AN AREA OF LOW CLOUDS BEHIND THE SURFACE TROUGH...ALONG THE INTERNATIONAL BORDER. THIS AREA OF CLOUDS HAS BEEN ADVECTING SOUTHWARD OVER THE PAST FEW HOURS...AND THE LATEST RAP GUIDANCE INDICATES THAT THIS TREND WILL CONTINUE. FOLLOWING THIS GUIDANCE MOST AREAS (EXCEPT PORTIONS OF SOUTHEAST NORTH DAKOTA) WILL LIKELY BE MOSTLY CLOUDY INTO AT LEAST THE EARLY AFTERNOON HOURS. THE THOUGHT IS THAT THE CLOUDS SHOULD BEGIN TO DISSIPATE ENOUGH BY MID-LATE AFTERNOON FOR MAX TEMPS TO BE ABLE TO REACH INTO THE MID-UPPER 70S. THE NEXT UPPER LEVEL WAVE AND ASSOCIATED SURFACE TROUGH/COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT INTO TUESDAY. FORCING AND INSTABILITY APPEAR TO BE STRONGER THAN THIS PAST SYSTEM...WHICH COULD LEAD TO MORE WIDESPREAD ACTIVITY. THE BEST SEVERE POTENTIAL WILL BE SOUTH OF THE FA WHERE INSTABILITY IS STRONGEST. HOWEVER...DEEP LAYER SHEAR WILL BE STRONG AND A FEW STRONGER STORMS WOULD SEEM POSSIBLE (ESPECIALLY TUESDAY AFTERNOON ACROSS SE ND INTO WC MN WHERE THE SFC FRONT WILL BE LOCATED DURING PEAK HEATING). .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 TUESDAY NIGHT-WEDNESDAY NIGHT...HIGH PRESSURE WILL AGAIN MOVE INTO THE REGION WHICH SHOULD LEAD TO MOSTLY DRY CONDITIONS. THURSDAY-SUNDAY NIGHT...00 UTC GFS/ECMWF SHOW SAME BASIC SYNOPTIC PATTERN...BUT DIFFER ON THE SPEED AT WHICH THE CLOSED CANADIAN LOW EJECTS INTO QUEBEC. THE ECMWF IS QUICKER THAN THE GFS AND THIS ALLOWS ANOTHER PACIFIC SHORT-WAVE TO MOVE INTO THE NORTHERN PLAINS NEXT WEEKEND. THE SLOWER GFS MAINTAINS DRY NORTHWEST FLOW ACROSS THE FORECAST AREA. GIVEN MODEL DIFFERENCES...WILL KEEP A MAINLY DRY FORECAST FRIDAY AND BEYOND. BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE THURSDAY AS ANOTHER COLD FRONT SWEEPS ACROSS THE REGION. COLD POOL ALOFT ASSOCIATED WITH DEEP CLOSED LOW WILL KEEP TEMPERATURES WELL BELOW MID-AUGUST NORMALS. HIGHS THURSDAY/ FRIDAY WILL STRUGGLE TO BREAK 70 DEGREES IN PLACES. A GRADUAL WARM-UP IS EXPECTED INTO THE WEEKEND...BUT STILL 5 TO 10 DEGREES COOLER THAN NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1130 PM CDT SUN AUG 4 2013 THERE IS A BAND OF IFR/MVFR CIGS TO THE NORTH OF DEVILS LAKE...THAT COULD MOVE INTO THE NORTHERN AREAS OVERNIGHT INTO MONDAY MORNING WILL MENTION SOME MVFR CIGS IN THE NORTH...AND THIS WILL HAVE TO BE MONITORED TO SEE IF IFR CIGS DEVELOP. OTHERWISE...WINDS WILL SHIFT TO THE NW BEHIND THE SFC BOUNDARY BUT REMAIN AT OR UNDER 10 KT WITH A CLEARING TREND MONDAY AFTERNOON FROM NW TO SE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...DK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1258 AM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 1258 AM CDT MON AUG 5 2013 WEAK COLD FRONT EXTENDED FROM NEAR GRAND FORKS SOUTHWESTWARD TO NEAR BISMARCK AND DICKINSON. ISOLATED SHOWERS/THUNDERSTORMS HAD DISSIPATED AND HAVE SLIGHT CHANCES OF THUNDER DIMINISHING TO NO CHANCES BY AROUND 4 AM. THE MAIN CHANGE IN THIS UPDATE IS TO INCLUDE THE MENTION OF AREAS OF FOG FOR WESTERN AND CENTRAL NORTH DAKOTA. FOLLOWING THE WEAK FRONT...LOW CLOUDS WERE MOVING IN FROM THE NORTH AND ALSO FORMING/EXPANDING ACROSS NORTH CENTRAL NORTH DAKOTA. LATEST SAT PICS INDICATED SCATTERED LOW CLOUDS OR FOG ALONG THE FRONT...AND FOG WAS SEEN IN LOW LYING AREAS AROUND BISMARCK - THUS THINKING FOG AND LOW CLOUDS WILL DOMINATE MUCH OF THE OVERNIGHT HOURS. ONLY MINOR CHANGES IN OVERNIGHT LOWS. UPDATE ISSUED AT 917 PM CDT SUN AUG 4 2013 UPDATE FOR EVENING/OVERNIGHT POPS. STRONG THUNDERSTORMS ACROSS THE SOUTH CENTRAL HAVE CONTINUED TO TREND DOWNWARD OVER THE PAST HOUR AS THEY MOVE INTO A LESS UNSTABLE AIRMASS. THIS TREND IS EXPECTED TO CONTINUE THROUGH LATE EVENING. CAN`T RULE OUT AN ISOLATED STORM WITH SMALL HAIL...BUT NO ADDITIONAL SEVERE WEATHER IS EXPECTED. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 330 PM CDT SUN AUG 4 2013 MAIN FORECAST PROBLEM IN THE SHORT TERM PERIOD IS THE CHANCE OF SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. MODELS HAVE BEEN HAVING A HARD TIME FIGURING OUT WHAT WILL TRANSPIRE LATE THIS AFTERNOON INTO THIS EVENING. MANY FAVORABLE FACTORS FOR CONVECTION ARE IN PLACE. STRONG UPPER LEVEL JET IS PROVIDING GOOD BULK SHEAR WITH INDIVIDUAL IMPULSES TRACKING ACROSS NORTHEAST MONTANA AND SOUTHERN SASKATCHEWAN. DEWPOINT HAVE CLIMBED INTO THE UPPER 50S TO LOWER 60S ACROSS THE AREA WITH AN INVERTED SURFACE TROUGH TRACKING SLOWLY EAST ACROSS WESTERN NORTH DAKOTA PROVIDING AN ADDITIONAL FOCUSING MECHANISM FOR CONVECTION. THE LIMITING FACTOR HAS BEEN THE EXTENSIVE CLOUD COVER PROVIDING MEAGER LOW LEVEL LAPSE RATES. 19Z KDIK LAPS SOUNDING STILL INDICATES AROUND 100 MB OF CIN TO BE OVERCOME. HOWEVER SKIES ARE BEGINNING TO CLEAR IN EASTERN MONTANA INTO WESTERN NORTH DAKOTA WITH A GOOD 3 HOURS OF HEATING BEFORE WE PASS OUR DIURNAL MAX AND CURRENTLY 1000-1500 J/KG OF CAPE AVAILABLE OVER FAR WESTERN NORTH DAKOTA. THE DIRECTIONAL SHEAR PROFILE DOES BECOME LESS FAVORABLE WITH SIGNIFICANT DRYING ALOFT TAKING PLACE BEHIND THE INVERTED TROUGH WHICH CURRENTLY LAYS OVER WESTERN NORTH DAKOTA. MESOSCALE MODELS HAVE BEEN ALL OVER THE PLACE WITH CONVECTION ACROSS WESTERN AND CENTRAL NORTH DAKOTA. ABOUT THE ONLY TREND THAT CAN BE SEEN IS THAT SUCCESSIVE RUNS HAVE BECOME LESS AND LESS OMINOUS FOR CONVECTION DEVELOPING OVER WESTERN OR CENTRAL NORTH DAKOTA THIS AFTERNOON OR THIS EVENING. WITH THIS SAID...STILL THINK THERE IS A WINDOW OF OPPORTUNITY FOR CONVECTION OVER CENTRAL NORTH DAKOTA LATE THIS AFTERNOON THROUGH LATE EVENING. THE 18Z RAP SHOWS CONVECTION TRYING TO DEVELOP OVER THE NORTH CENTRAL LATE THIS AFTERNOON...SPREADING SOUTHWEST INTO SOUTHWEST NORTH DAKOTA EARLY THIS EVENING. BUT THE STRONGEST CONVECTION REMAIN OVER THE NORTH CENTRAL INTO EASTERN NORTH DAKOTA...CLOSEST TO THE MID LEVEL SHORTWAVE TROUGH. THE 12Z WRF DID NOT HAVE A GOOD HANDLE ON CONVECTION ACROSS THE NORTH...BUT DOES DEVELOP A LINE OF CONVECTION ACROSS THE SOUTHWEST BETWEEN 21-22Z. EACH SUCCESSIVE RUN OF THE HRRR CONTINUES DEPICT WEAKER CONVECTION DEVELOPING OVER CENTRAL AND EASTERN NORTH DAKOTA THIS EVENING. SETTLED ON A 20-30 POPS OVER THE CENTRAL INTO THE SOUTHWEST LATE THIS AFTERNOON SPREADING INTO CENTRAL AND EASTERN NORTH DAKOTA TONIGHT. WILL NOT MENTION SEVERE WORDING BUT A FEW STRONG TO POSSIBLY SEVERE CELLS CAN NOT BE RULED OUT GIVEN THE STRONG SHEAR AND INCREASING CAPE. CONVECTION...IF IT DOES DEVELOP SHOULD MOVE OUT OF THE EASTERN CWA AFTER MIDNIGHT. WE THEN GET A PERIOD OF UPPER LEVEL RIDGING MONDAY AHEAD OF THE NEXT SHORTWAVE TROUGH...AND THE STRONG SHORTWAVE ASSOCIATED WITH THE RETROGRADING UPPER LEVEL LOW OVER DROPPING DOWN FROM THE HUDSON BAY. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 330 PM CDT SUN AUG 4 2013 THE NORTHERN PLAINS WILL BE UNDER NORTHWEST FLOW ALOFT MONDAY NIGHT WITH UPPER LEVEL RIDGING ACROSS THE SOUTHERN PLAINS AND DEEP LOW PRESSURE OVER THE WESTERN HUDSON BAY. WILL SEE INCREASING CHANCES OF SHOWERS/THUNDERSTORMS MONDAY EVENING WEST AND LATE MONDAY NIGHT THROUGH TUESDAY MORNING AREA WIDE AS A POTENT EMBEDDED S/WV ROTATES THROUGH THE FLOW AND INTO NORTH DAKOTA...IN ADDITION TO A SFC TROUGH/COLD FRONTAL BOUNDARY PUSHING SOUTH ACROSS THE STATE INTO TUESDAY MORNING. BY TUESDAY AFTERNOON...THE MAIN AREA OF SHOWERS/THUNDERSTORMS ASSOCIATED WITH THE COLD FRONT WILL HAVE MOVED SOUTH AND EAST OF CENTRAL NORTH DAKOTA. WILL NEED TO KEEP AN EYE ON THE SOUTHEAST DURING THE AFTERNOON FOR A STRONGER STORM WHERE MODELS PROJECT NEAR 1000 J/KG OF CAPE AND LITTLE IF ANY CIN. BY TUESDAY EVENING THE UPPER LEVEL LOW IS FORECAST TO BE BETWEEN HUDSON BAY AND LAKE WINNIPEG...MAINTAINING STRONG NORTHWEST FLOW ALOFT THROUGH THURSDAY (POSSIBLY INTO FRIDAY) WITH THE UPPER LOW REMAINING QUASI-STATIONARY. LINGERING LOW LEVEL MOISTURE COUPLED WITH EMBEDDED ENERGY IN THE FLOW ALOFT WILL MAINTAIN SOME CHANCE FOR DIURNALLY DRIVEN SHOWERS/ISOLATED THUNDERSTORMS BOTH WEDNESDAY AND THURSDAY. UPPER LOW PROPAGATES SLOWLY EAST TO OVER ONTARIO FRIDAY INTO FRIDAY NIGHT...WITH A RIDGE BUILDING INTO THE MONTANA ROCKIES. HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE DAKOTAS THURSDAY NIGHT...REMAINING IN PLACE WELL INTO THE WEEKEND. THIS WILL LEAD TO MAINLY DRY CONDITIONS AND CONTINUED BELOW NORMAL TEMPERATURES OVER MOST OF THE CWA THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1258 AM CDT MON AUG 5 2013 LARGE AREA OF LOW CLOUDS AND FOG WAS FORMING/MOVING IN BEHIND A WEAK COLD FRONT THAT EXTENDED FROM NEAR KGFK TO NEAR KBIS AND KDIK AT 06Z. ADDED TEMPO GROUPS FOR MVFR/IFR CIGS AND VSBYS FOR TAF SITES. EXPECT DISSIPATING FOG AND LOWER CLOUDS BY AROUND 15Z/16Z IN KISN/KDIK/KMOT/KBIS AND BY AROUND 18Z AT KJMS. EXPECT SCATTERED THUNDERSTORMS IN WESTERN NORTH DAKOTA BY/AFTER 00Z AHEAD OF THE NEXT COLD FRONT THAT IS EXPECTED TO MOVE SOUTHEASTWARD ACROSS NORTH DAKOTA LATE MONDAY EVENING/NIGHT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JV SHORT TERM...TWH LONG TERM...NH AVIATION...JV
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
200 AM EDT MON AUG 5 2013 .SYNOPSIS... A BELT OF FAST WNW FLOW ALOFT WILL EXTEND FROM THE DAKOTAS TO THE MID-ATLANTIC COAST THROUGH THE MIDDLE OF THE WEEK...AS THE DEEP TROUGH OVER THE NORTHEAST SLIDES OFFSHORE AND PIVOTS AROUND A LARGE VORTEX MOVING SOUTHWEST FROM HUDSON BAY INTO SOUTH-CENTRAL CANADA. UPPER LEVEL HEIGHTS SHOULD RISE DURING THE SECOND HALF OF THE WEEK AS THE MID-LEVEL FLOW SHIFTS TO THE WEST-SOUTHWEST. AT THE SURFACE...HIGH PRESSURE OVER LK MICHIGAN THIS EVENING WILL MIGRATE OVER PENNSYLVANIA ON MONDAY BEFORE SLIDING OFF THE COAST MONDAY NIGHT. INCREASING MOISTURE IN ADVANCE OF A PLAINS/MIDWEST FRONTAL SYSTEM WILL BRING PERIODS RAIN FROM TUESDAY THROUGH THE END OF THE WEEK. BELOW NORMAL TEMPERATURES WILL MODERATE THROUGH THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... STAGE IS SET FOR A VERY COOL NIGHT /FOR EARLY AUGUST/ ACROSS CENTRAL PA...AS NEGATIVE PWAT AND 8H TEMPS ANOMALIES ON THE ORDER OF -2SD WILL ACCOMPANY SFC HIGH BUILDING OVR THE STATE. KCLE RADAR LOOP EARLIER THIS EVENING SHOWED A FINE LINE PUSHING INTO NE OHIO AND NW PA. THIS BOUNDARY REPRESENTS A SFC TROF SEPARATING DRY AIR OVR CENTRAL PA FROM EVEN DRIER AIR PUSHING IN FROM THE NORTH. LATEST SFC-8H LYR DWPTS FROM NAM AND RAP PICK UP THIS FEATURE WELL AND SUGGEST THE BNDRY AND DRIEST AIR NEVER REACH THE LAUREL HIGHLANDS. THEREFORE...EXPECT THE NW MTNS TO SEE THE COOLEST TEMPS RELATIVE TO NORMAL WITH MINS DROPPING INTO THE U30S IN THE NORMALLY COLDER VALLEYS. ONLY POSSIBLE WILD CARD WILL BE CIRRUS SPREADING IN AHEAD OF FAST-MOVING SHORTWAVE OVR THE GRT LKS. CURRENT THINKING IS THAT THESE HIGH CLOUDS WILL BE THIN ENOUGH TO NOT SIGNIFICANTLY DAMPEN RADIATIONAL COOLING. HAVE LOWERED OVERNIGHT TEMPS TO ARND 40F OVR THE NW MTNS...TO THE M50S FROM MDT SOUTH AND EAST. A NEARLY CALM WIND...AND WATER TEMPS NEARLY 30F WARMER THAN ANTICIPATED AIR TEMPS...SHOULD RESULT IN A NEAR CERTAINTY OF FOG LATE TONIGHT IN THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES...ESP NORTH OF I-80. PATCHY FOG ALSO LIKELY FURTHER EAST WITHIN THE RIDGE/VALLEY REGION FROM AOO TO UNV AND SEG...ESP NEAR ANY BODIES OF WATER. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... ANY PATCHY FOG WILL LIFT/DISSIPATE BETWEEN 13-15Z. THE FAIR/DRY WEATHER WILL PREVAIL TOMORROW WITH SFC HIGH PRESSURE IN CONTROL OF THE REGIONAL WEATHER PATTERN. HIGH QUALITY CANADIAN AIRMASS WILL FOSTER COMFORTABLE TEMPS AND HUMIDITY. A DECENT AMT OF SUNSHINE SHOULD EASILY ALLOW MIXING TO 850MB AND ENS MEAN 850 TEMPS ARND 10C SHOULD TRANSLATE TO MAX TEMPS IN THE 70S. AS THE SIGNIFICANT AREA OF COOL HIGH PRESSURE OVER PA SLIDES TO THE EAST LATE MONDAY INTO MONDAY NIGHT...A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 06-12Z TUE TIMEFRAME. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... WEAK TO MODERATE WSWRLY FLOW ALOFT AT THE START OF THE PERIOD WILL TURN MORE NWRLY AS HUDSON BAY UPPER LOW PROGRESSES INTO EASTERN CANADA BY THE END OF THE PERIOD. PLENTY OF WEAK SHORTWAVE TROFS WILL BE PRESENT TO BRING WEAK FRONTS THROUGH THE REGION DURING THE PERIOD. A STG WAA PATTERN WILL EVOLVE EWD FROM THE OH VLY. THIS IS SHOWN NICELY BY A BROAD SURGE OF POSITIVE 850-700MB THETA-E ADVECTION. DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING WARM FRONT WILL AID IN INCREASING LLVL MSTR...AND 90KT JET EMBEDDED WITHIN BELT OF FAST WNW FLOW ALOFT WILL PROVIDE SYNOPTIC LIFT. CONSENSUS OF 04/12Z OPRN MDLS AND ENS GUIDANCE SUPPORTS CHC FOR SHOWERS ACRS THE SW 1/2 OF THE CWA IN THE 00-12Z TUE TIMEFRAME UPPER RIDGE OVER NUNAVUT/NW TERRITORIES WILL MAINTAIN MEAN TROUGHING OVER SERN CANADA...ANCHORED BY A CLOSED LOW TRACKING EWD ACRS MANITOBA/ONTARIO INTO QUEBEC BY THE END OF THE PERIOD. MODEL SPREAD IN THE TIMING OF THE LOW IS IMPACTING SFC/PCPN DETAILS DOWNSTREAM. SHORTWAVE ENERGY ROTATING AROUND THE BASE OF THE CLOSED LOW WILL PROPEL A SFC FRONT FROM THE NRN PLAINS SEWD THRU THE MIDWEST/OH VLY TUE-WED BEFORE SLOWING ITS PROGRESSION OVER THE APPLCHNS AND MID-ATLC STATES THU-FRI. WAVES OF LOW PRES RIDING ALONG THE FRONT WILL BE ACCOMPANIED BY RNFL OF VARYING INTENSITY WED-FRI...WITH SCT CONVECTION PRECEDING A WARM FRONT ON TUE. THE OVERALL PATTERN LOOKS PERIODICALLY WET AND UNSETTLED...WITH SEVERAL BOUTS OF SHOWERS/TSTMS TUE-FRI. SOME MODERATION IN DAILY TEMPS SHOULD OCCUR AHEAD OF THE FRONT. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... HIGH PRESSURE PROVIDING WHAT SHOULD BE A GOOD RADIATIONAL COOLING NIGHT. EXPECT SOME FOG FORMATION OVERNIGHT...BUT A PERSISTENT LIGHT NORTHWEST WIND...COMBINED WITH SOME HIGH CLOUDS...MAY LIMIT FOG EXTENT. AFTER MORNING FOG...LOOK FOR HIGH PRESSURE TO PROVIDE VFR CONDITIONS MONDAY. WARM ADVECTION WILL INTRODUCE LOW CHANCE SHRA/TSRA BEGINNING MONDAY NIGHT INTO TUESDAY....WITH GREATER CHANCES WEDNESDAY AS WARM FRONT MOVES ACROSS THE REGION. APPROACHING COLD FRONT WILL THEN TRIGGER POSSIBLE SHRA/TSRA LATER THURSDAY...MAINLY IN THE NORTHWEST. MORE WIDESPREAD ACTIVITY FRIDAY WITH COLD FRONTAL PASSAGE. OUTLOOK... TUE-WED...MAINLY VFR...BUT A CHC OF SHOWERS AND STORMS. THU-FRI...GENERALLY VFR...BUT RESTRICTIONS IN SHRA/TSRA. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...CERU/STEINBUGL LONG TERM...GARTNER/STEINBUGL AVIATION...JUNG/MARTIN
SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.

NOT ANTICIPATING ANY MAJOR CHANGES TNT. DID LOWER POPS SOME FOR THE WESTERN CWA WHERE IT APPEARS ANY CONVECTION IS HAVING A HARD TIME GETTING ITS ACT TOGETHER OVER THE WESTERN HIGH PLAINS. FOR THE NORTHEAST CWA WILL MAINTAIN DECENT CHC POPS. NICE LOOKING S/W IN WV IMAGERY OVER WESTERN NORTH DAKOTA IS HELPING PROVIDE THE LIFT FOR SOME STORMS SOUTH OF BISMARCK. SOME OF THAT ACTIVITY MAY MAKE ITS WAY DOWN INTO NORTHERN SOUTH DAKOTA THIS EVENING. ONLY PROBLEM IS THAT ITS STILL FAIRLY STABLE OVER THE NORTHEAST PART OF THE CWA PER THE 00Z RAOB. MEANWHILE THE HRRR CONTINUES TO DEVELOP ELEVATED OVERNIGHT STUFF ON THE NOSE OF THE LLJ AHEAD OF THAT PREVIOUSLY MENTIONED S/W...SO WILL LEAVE POPS AS IS DESPITE SOME CONCERNS ABOUT TOO MUCH STABILITY OVER THE EASTERN CWA. TEMPS LOOK OKAY. && .PREVIOUS DISCUSSION... .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT A WEALTH OF CLOUDS COVER THE CWA THIS AFTERNOON...MUCH OF IT MVFR ACROSS CENTRAL SD. THE SUMMER SUN HAS NOT BURNED THIS OFF AND VIS SATELLITE INDICATES IT IS STILL STUBBORN TO LEAVE AND RATHER THICK. LOOKS LIKE SKIES WILL STAY MOSTLY CLOUDY THROUGH THE AFTERNOON. WITH THE ABUNDANCE OF CLOUDS...THE ATMOSPHERE HAS NOT BEEN ALLOWED TO DESTABILIZE. THE ONLY AREA THAT HAS RECEIVED A GOOD AMOUNT OF SUN TODAY IS FAR WESTERN SD. MESOANALYSIS SHOWS THIS AREA IS PUSHING 2000 J/KG MLCAPE WITH 50 KNOTS 0-6KM SHEAR. FARTHER EAST TOWARDS THE MISSOURI VALLEY...ONLY ABOUT 500 J/KG MLCAPE AND A LARGE CAP STILL IN PLACE. SPC SLIGHT RISK THREAT STILL HIGHLIGHTS WESTERN SD AND THIS LOOKS GOOD BASED ON CURRENT SITUATION. THE CWA HAS BEEN QUIET ALL DAY LONG AND HAD TO CUT POPS BACK TO SLIGHT CHANCE THEN EVENTUALLY TO NOTHING THROUGHOUT THE DAY. RATHER DIFFICULT PRECIP FORECAST TONIGHT AS WELL AND HI RES MODELS NOT OFFERING UP MUCH HELP. IT APPEARS THERE MAY BE TWO AREAS OF FOCUS...WITH THE POSSIBILITY OF A LARGE PORTION OF THE CWA FALLING IN BETWEEN THE TWO BEST AREAS OF PRECIP POTENTIAL. THE FIRST AREA IS THE AREA OF WESTERN SD. WHATEVER FIRES LATER THIS AFTERNOON AND EVENING COULD BECOME STRONG TO SEVERE AND EVENTUALLY MAKE ITS WAY INTO THE FAR WESTERN COUNTIES BY THIS EVENING. BUT ANYTHING THAT MOVES EAST WILL ENCOUNTER MUCH MORE STABLE AIR. THE NEXT AREA TO WATCH IS THE FAR NORTHEAST CWA LATER THIS EVENING AND OVERNIGHT. WATER VAPOR IMAGERY SHOWS TWO SEPARATE WAVES OF ENERGY ACROSS MONTANA AND FAR SOUTHERN CANADA. THESE WAVES WILL SLIDE EAST-SOUTHEAST INTO THE REGION OVERNIGHT AND MODELS ARE SHOWING SHOWERS AND STORMS ACROSS EASTERN ND...FAR NORTHEAST SD AND INTO MN THIS EVENING AND OVERNIGHT. MUCAPE INCREASES TO 1000-1500 J/KG WITH BULK SHEAR OF AROUND 50 KNOTS. THERE COULD BE A FEW STRONGER STORMS WITHIN THE WAA REGIME ACROSS THE FAR NORTHEAST CWA LATER TONIGHT. TRIED TO CONSTRUCT POP GRIDS WITH HIGHER CHANCES ACROSS THE FAR NORTHEAST AND FAR SOUTHWEST...BUT CONFIDENCE THIS GO AROUND IS RATHER LOW. AFTER QUIET CONDITIONS ON MONDAY...WILL THEN BE WATCHING THE COLD FRONTAL PASSAGE ON TUESDAY. FAIRLY POTENT FRONT MOVING THROUGH DURING THE DAY AND CHANCES FOR SHOWERS AND STORMS LOOK PRETTY GOOD. THERE COULD BE A FEW STRONGER STORMS ON TUESDAY WITH 1000-1500 J/KG GENERALLY SPEAKING AND 50+ KNOTS OF SHEAR. ALTHOUGH...STRONGEST INSTABILITY IS SOUTH OF THE REGION. .LONG TERM...WEDNESDAY THROUGH SUNDAY BELOW NORMAL TEMPERATURES WILL CONTINUE TO RULE THE LONG TERM PERIOD. A STRONG SOUTHERN CANADIAN COLD VORTEX WILL WOBBLE SLOWLY EAST THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. THIS WILL PUT US IN CONTINUED COOL NORTHWEST FLOW. THIS FLOW WILL BECOME MORE WEST NORTHWEST THROUGH THE WEEKEND AS AN UPPER LEVEL RIDGE AXIS PUSHES IN FROM THE WEST. THE MODELS SHOW SURFACE CANADIAN HIGH PRESSURE DOMINATING THROUGH MOST OF THE LONG TERM. A COLD FRONT COMING ACROSS THE CWA FOR WEDNESDAY NIGHT AND THURSDAY WILL BRING CHANCES OF SHOWERS AND THUNDERSTORMS TO THE ENTIRE CWA. OTHERWISE...THE SHOWER/STORM CHANCES WILL BE CONFINED TO ALONG AND WEST OF THE MISSOURI RIVER FOR MOST OF THE REST OF THE LONG TERM AS SHORT WAVES COME OVER THE WESTERN RIDGE. AREAS MAINLY EAST OF THE MISSOURI RIVER SHOULD REMAIN MORE ON THE STABLE AND DRIER SIDE. ALSO WITH THE SURFACE HIGH PRESSURE...DONT EXPECT MUCH FOR WIND THROUGH THE ENTIRE LONG TERM. HIGHS THROUGH THE ENTIRE LONG TERM SHOULD BE MOSTLY IN THE 70S TO THE LOWER 80S ACROSS THE CWA. && .AVIATION... 06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS MVFR CIGS ARE EXPECTED FOR A COUPLE MORE HOURS TONIGHT AT KABR/KATY. OTHERWISE...VFR FLYING WEATHER CONDITIONS WILL PREVAIL. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...TDK/DORN SHORT TERM...TMT LONG TERM...MOHR AVIATION...DORN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
1036 AM CDT MON AUG 5 2013 .UPDATE... IN THE NEAR TERM...WILL CONTINUE TO MONITOR CONVECTIVE TRENDS ACROSS NORTHEAST SECTIONS FOR EXCESSIVE RAINFALL POTENTIAL. EXPECT ADDITIONAL DEVELOPMENT ACROSS MOST AREAS THIS AFTERNOON...AS SMALL SCALE BOUNDARIES ACT ON A VERY UNSTABLE ATMOSPHERIC COLUMN. 55 && .PREV DISCUSSION... /ISSUED 641 AM CDT MON AUG 5 2013/ AVIATION... NORTHWEST FLOW WILL BRING A SHORT WAVE ACROSS THE AREA TODAY WITH SHOWERS AND THUNDERSTORMS. PRECIPITATION IS SCATTERED ACROSS THE NORTHEAST HALF OF THE STATE. AN MCS IS EXPECTED TO DEVELOP TONIGHT IN KANSAS AND MOVE INTO NORTH ARKANSAS AGAIN TUESDAY MORNING. HIGH PRESSURE AND DRY WEATHER IS EXPECTED FOR WEDNESDAY...BUT THE ACTIVE WEATHER PATTERN WILL RETURN FOR THURSDAY AND THROUGH THE WEEKEND. PREV DISCUSSION... /ISSUED 334 AM CDT MON AUG 5 2013/ DISCUSSION... DIFFERENT DAY...SAME FORECAST. MAIN CONCERNS REMAIN CHANCES OF CONVECTION WITH THUNDERSTORM COMPLEXES MOVING ACROSS AR...MAINLY TODAY AND TUESDAY...WITH POSSIBLE HEAVY RAIN THREAT AND FLASH FLOODING POTENTIAL. TEMPERATURE FORECAST WILL BE LOWER THAN NORMAL OVER NORTHERN AR...WHILE AROUND NORMAL TO A BIT ABOVE SOUTHERN AREAS. LOWER RAIN CHANCES EXPECTED WEDNESDAY AND THURSDAY. MAIN CONVECTION TONIGHT HAS BEEN FOCUSED OVER EASTERN KS TO MO...WITH LIGHT CONVECTION OVER EASTERN OK TO NORTHERN AR. TONIGHT HAVE SEEN THE MCV AHEAD OF LAST NIGHT...AND CONVECTION HAS MADE IT TO NORTHERN AR. ALSO DID SEE CONVECTION HELPED WITH THE WEAK WARM FRONT OVER SOUTHERN AR. THIS MORNING IT REMAINS OVER OVER SOUTHERN AR WHERE SOUTH OF THE BOUNDARY DEW POINT TEMPS WERE IN THE MID 70S...WHILE MAINLY LOWER 70S THE REST OF AR. 00Z SOUNDING AT KLZK AND KSGF CONTINUED THE PRECIP WATER VALUE AROUND 2 INCHES AND UNSTABLE. A LOW LEVEL JET WAS EVIDENT INTO EASTERN KS TO EASTERN OK...THEN INTO SW MO. THE UPPER NW PATTERN CONTINUES INTO THE REGION...WITH THE LATEST SHORT WAVE MOVING OVER THE OZARKS OF OK...MO TO AR. ADDITIONAL ENERGY WAS SEEN UPSTREAM WHICH WILL AFFECT THE REGION MONDAY NIGHT. RAINS OVER NORTHERN AR WERE LOWER THAN PREVIOUS DAY BUT OVERALL VALUES OVER THE LAST SEVERAL DAYS ARE 1 TO 3 INCHES. SO FLASH FLOOD WATCH WILL BE IN AFFECT THROUGH MONDAY NIGHT...WITH THE POTENTIAL FOR FLASH FLOODING WITH HEAVY RAIN. SHORT TERM...TODAY THROUGH THURSDAY NIGHT TODAY`S FORECAST WILL START WITH A HIGH POP OVER NORTHERN AR DUE TO ON GOING CONVECTION. THE FLASH WATCH WILL CONTINUE THROUGH AT LEAST TONIGHT WITH MODELS SHOWING ANOTHER MCV EXPECTED TO AFFECT PARTS OF NORTHERN AR. WRF AND HRRR MODELS ARE A BIT DIFFERENT IN THEIR SOLUTIONS EARLY TODAY...AND LIKE HRRR BASED ON ON GOING TRENDS. MAIN SURGE OF CONVECTION WILL CONTINUE OVER NORTHERN TO PARTS OF NORTHERN CENTRAL AR TODAY...WITH A E TO SE MOVEMENT AS IT MOVES FROM KS AND MO...THEN INTO AR. PRECIP WATER VALUES REMAIN AROUND 2 INCHES OR MORE...AND STORMS WILL PRODUCE HEAVY RAIN. FLASH FLOOD WATCH THOSE AREAS THAT HAVE RECEIVED RAIN OVER THE LAST FEW DAYS AND WHERE TODAY`S HEAVY RAIN BAND WILL BE. LATER TODAY THE MCV MOVES EAST OF AR...THEN TONIGHT THE UPPER RIDGE IS FORECAST TO BUILD A BIT MORE EAST...AND TAKE THE NEXT COMPLEX MORE NORTH TO EAST...WHICH WILL AFFECT MORE N TO NE AR. THIS HOLDS INTO TUESDAY WITH FORECAST POP MORE OVER N TO NE AR. STILL SOME CHANCE WILL BE OVER MUCH OF THE STATE...BUT SHOULD BE LOWER. TUESDAY NIGHT TO WEDNESDAY AND THURSDAY...CONVECTION IS ALSO EXPECTED TO BE MORE FOCUSED OVER NORTHERN AR WITH MODEL FORECAST SHORT WAVE ENERGY. A FLASH FLOOD WATCH WILL PROBABLY BE DROP LATER TUESDAY TO WEDNESDAY BUT MAY HAVE TO BE CONSIDERED IF MORE HEAVY CONVECTION IS ANTICIPATED. OTHERWISE TEMPERATURES WILL GRADUALLY WARM INTO MID WEEK AS THE UPPER RIDGE LOWERS RAIN CHANCES A BIT AND THE HEAT OVER TEXAS MOVES INTO AR. LONG TERM...FRIDAY THROUGH SUNDAY UPPER LEVEL HIGH PRESSURE WILL BE OVER ARKANSAS THROUGH THE LONG TERM PERIOD. ALSO...THE HIGH WILL STRENGTHEN NORTHWEST INTO THE NORTHERN ROCKIES. A COLD FRONT WILL MOVE INTO NORTH ARKANSAS FRIDAY AND STALL. THE FRONT SHOULD HANG AROUND NORTH ARKANSAS THROUGH THE WEEKEND. THIS WILL KEEP CHANCES OF SHOWERS AND THUNDERSTORMS IN THE FORECAST WITH BEST CHANCES IN THE NORTH THROUGH THE PERIOD. THE HIGH PRESSURE MAY SHIFT WESTWARD SUNDAY AND PROVIDE MORE OF A NORTHWEST FLOW AND BETTER CHANCES OF PRECIPITATION. NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 86 72 91 73 / 80 30 30 20 CAMDEN AR 94 76 97 75 / 50 10 10 10 HARRISON AR 88 72 91 72 / 90 30 20 20 HOT SPRINGS AR 93 74 95 74 / 40 20 10 10 LITTLE ROCK AR 90 74 94 75 / 60 20 20 10 MONTICELLO AR 93 76 96 76 / 50 10 10 10 MOUNT IDA AR 94 74 96 74 / 40 10 10 10 MOUNTAIN HOME AR 87 71 90 72 / 90 30 30 20 NEWPORT AR 86 73 91 74 / 60 30 30 20 PINE BLUFF AR 91 75 95 75 / 50 20 20 10 RUSSELLVILLE AR 90 73 94 74 / 60 20 20 20 SEARCY AR 88 74 92 74 / 60 20 20 20 STUTTGART AR 90 75 94 75 / 60 20 20 10 && .LZK WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR BAXTER-BOONE- CLEBURNE-FULTON-INDEPENDENCE-IZARD-JOHNSON-MARION-NEWTON-POPE- SEARCY-SHARP-STONE-VAN BUREN. && $$ AVIATION...99
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
641 AM CDT MON AUG 5 2013 .AVIATION... NORTHWEST FLOW WILL BRING A SHORT WAVE ACROSS THE AREA TODAY WITH SHOWERS AND THUNDERSTORMS. PRECIPITATION IS SCATTERED ACROSS THE NORTHEAST HALF OF THE STATE. AN MCS IS EXPECTED TO DEVELOP TONIGHT IN KANSAS AND MOVE INTO NORTH ARKANSAS AGAIN TUESDAY MORNING. HIGH PRESSURE AND DRY WEATHER IS EXPECTED FOR WEDNESDAY...BUT THE ACTIVE WEATHER PATTERN WILL RETURN FOR THURSDAY AND THROUGH THE WEEKEND. && .PREV DISCUSSION... /ISSUED 334 AM CDT MON AUG 5 2013/ DISCUSSION... DIFFERENT DAY...SAME FORECAST. MAIN CONCERNS REMAIN CHANCES OF CONVECTION WITH THUNDERSTORM COMPLEXES MOVING ACROSS AR...MAINLY TODAY AND TUESDAY...WITH POSSIBLE HEAVY RAIN THREAT AND FLASH FLOODING POTENTIAL. TEMPERATURE FORECAST WILL BE LOWER THAN NORMAL OVER NORTHERN AR...WHILE AROUND NORMAL TO A BIT ABOVE SOUTHERN AREAS. LOWER RAIN CHANCES EXPECTED WEDNESDAY AND THURSDAY. MAIN CONVECTION TONIGHT HAS BEEN FOCUSED OVER EASTERN KS TO MO...WITH LIGHT CONVECTION OVER EASTERN OK TO NORTHERN AR. TONIGHT HAVE SEEN THE MCV AHEAD OF LAST NIGHT...AND CONVECTION HAS MADE IT TO NORTHERN AR. ALSO DID SEE CONVECTION HELPED WITH THE WEAK WARM FRONT OVER SOUTHERN AR. THIS MORNING IT REMAINS OVER OVER SOUTHERN AR WHERE SOUTH OF THE BOUNDARY DEW POINT TEMPS WERE IN THE MID 70S...WHILE MAINLY LOWER 70S THE REST OF AR. 00Z SOUNDING AT KLZK AND KSGF CONTINUED THE PRECIP WATER VALUE AROUND 2 INCHES AND UNSTABLE. A LOW LEVEL JET WAS EVIDENT INTO EASTERN KS TO EASTERN OK...THEN INTO SW MO. THE UPPER NW PATTERN CONTINUES INTO THE REGION...WITH THE LATEST SHORT WAVE MOVING OVER THE OZARKS OF OK...MO TO AR. ADDITIONAL ENERGY WAS SEEN UPSTREAM WHICH WILL AFFECT THE REGION MONDAY NIGHT. RAINS OVER NORTHERN AR WERE LOWER THAN PREVIOUS DAY BUT OVERALL VALUES OVER THE LAST SEVERAL DAYS ARE 1 TO 3 INCHES. SO FLASH FLOOD WATCH WILL BE IN AFFECT THROUGH MONDAY NIGHT...WITH THE POTENTIAL FOR FLASH FLOODING WITH HEAVY RAIN. SHORT TERM...TODAY THROUGH THURSDAY NIGHT TODAY`S FORECAST WILL START WITH A HIGH POP OVER NORTHERN AR DUE TO ON GOING CONVECTION. THE FLASH WATCH WILL CONTINUE THROUGH AT LEAST TONIGHT WITH MODELS SHOWING ANOTHER MCV EXPECTED TO AFFECT PARTS OF NORTHERN AR. WRF AND HRRR MODELS ARE A BIT DIFFERENT IN THEIR SOLUTIONS EARLY TODAY...AND LIKE HRRR BASED ON ON GOING TRENDS. MAIN SURGE OF CONVECTION WILL CONTINUE OVER NORTHERN TO PARTS OF NORTHERN CENTRAL AR TODAY...WITH A E TO SE MOVEMENT AS IT MOVES FROM KS AND MO...THEN INTO AR. PRECIP WATER VALUES REMAIN AROUND 2 INCHES OR MORE...AND STORMS WILL PRODUCE HEAVY RAIN. FLASH FLOOD WATCH THOSE AREAS THAT HAVE RECEIVED RAIN OVER THE LAST FEW DAYS AND WHERE TODAY`S HEAVY RAIN BAND WILL BE. LATER TODAY THE MCV MOVES EAST OF AR...THEN TONIGHT THE UPPER RIDGE IS FORECAST TO BUILD A BIT MORE EAST...AND TAKE THE NEXT COMPLEX MORE NORTH TO EAST...WHICH WILL AFFECT MORE N TO NE AR. THIS HOLDS INTO TUESDAY WITH FORECAST POP MORE OVER N TO NE AR. STILL SOME CHANCE WILL BE OVER MUCH OF THE STATE...BUT SHOULD BE LOWER. TUESDAY NIGHT TO WEDNESDAY AND THURSDAY...CONVECTION IS ALSO EXPECTED TO BE MORE FOCUSED OVER NORTHERN AR WITH MODEL FORECAST SHORT WAVE ENERGY. A FLASH FLOOD WATCH WILL PROBABLY BE DROP LATER TUESDAY TO WEDNESDAY BUT MAY HAVE TO BE CONSIDERED IF MORE HEAVY CONVECTION IS ANTICIPATED. OTHERWISE TEMPERATURES WILL GRADUALLY WARM INTO MID WEEK AS THE UPPER RIDGE LOWERS RAIN CHANCES A BIT AND THE HEAT OVER TEXAS MOVES INTO AR. LONG TERM...FRIDAY THROUGH SUNDAY UPPER LEVEL HIGH PRESSURE WILL BE OVER ARKANSAS THROUGH THE LONG TERM PERIOD. ALSO...THE HIGH WILL STRENGTHEN NORTHWEST INTO THE NORTHERN ROCKIES. A COLD FRONT WILL MOVE INTO NORTH ARKANSAS FRIDAY AND STALL. THE FRONT SHOULD HANG AROUND NORTH ARKANSAS THROUGH THE WEEKEND. THIS WILL KEEP CHANCES OF SHOWERS AND THUNDERSTORMS IN THE FORECAST WITH BEST CHANCES IN THE NORTH THROUGH THE PERIOD. THE HIGH PRESSURE MAY SHIFT WESTWARD SUNDAY AND PROVIDE MORE OF A NORTHWEST FLOW AND BETTER CHANCES OF PRECIPITATION. NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 86 72 91 73 / 80 30 30 20 CAMDEN AR 94 76 97 75 / 50 10 10 10 HARRISON AR 88 72 91 72 / 90 30 20 20 HOT SPRINGS AR 93 74 95 74 / 40 20 10 10 LITTLE ROCK AR 90 74 94 75 / 60 20 20 10 MONTICELLO AR 93 76 96 76 / 50 10 10 10 MOUNT IDA AR 94 74 96 74 / 40 10 10 10 MOUNTAIN HOME AR 87 71 90 72 / 90 30 30 20 NEWPORT AR 86 73 91 74 / 60 30 30 20 PINE BLUFF AR 91 75 95 75 / 50 20 20 10 RUSSELLVILLE AR 90 73 94 74 / 60 20 20 20 SEARCY AR 88 74 92 74 / 60 20 20 20 STUTTGART AR 90 75 94 75 / 60 20 20 10 && .LZK WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH THIS EVENING FOR BAXTER-BOONE-CLEBURNE- FULTON-INDEPENDENCE-IZARD-JOHNSON-MARION-NEWTON-POPE-SEARCY- SHARP-STONE-VAN BUREN. && $$ AVIATION...51
AREA FORECAST DISCUSSION
NWS PUEBLO CO
707 AM MDT MON AUG 5 2013 .UPDATE... ISSUED AT 703 AM MDT MON AUG 5 2013 UPDATED GRIDS/ZONES FOR SLIGHTLY LESS SKY COVERAGE OVER PORTIONS OF THE PLAINS...AND TO DROP LOW POPS FOR THE MTS FOR THE EARLY MON MORNING PERIOD. HIGH CLOUDS CONTINUE TO STREAM UP FROM THE SOUTH...SO STILL THINK WE WILL SEE MORE CLOUDS THAN SUN TODAY. MOST RECENT HRRR IS SHOWING FAIRLY STRONG QPF MOVING OVER THE WALDO AND BLACK FOREST AREAS AFTER 23Z TODAY...WHILE OTHER MODELS ARE A BIT MORE SPARSE. WILL HAVE TO WATCH CONVECTIVE TRENDS CLOSELY THIS AFTERNOON GIVEN THE RECENT HEAVY RAINS. ROSE && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 355 AM MDT MON AUG 5 2013 ...A BIT QUIETER TODAY...STILL SOME FLOODING CONCERNS... CURRENTLY...JUST A FEW SHOWERS LINGERING NR THE KS AND OK BORDERS. KALS FINALLY DRYING OUT AFTER A COUPLE HOURS OF SOME FAIRLY GOOD RAINFALL...NEARLY HALF AN INCH...MOST OF WHICH WAS INVISIBLE TO RADAR DUE TO BLOCKAGE AND DISTANCE FROM THE WSR NETWORK. WILL PROBABLY SEE SOME LOW CLOUDS IN THE VALLEY THIS MORN. OTHERWISE...JUST SOME LOW CLOUDS AND A BIT OF FG POSSIBLE OVER THE FAR SERN PLAINS...ESPECIALLY KIOWA COUNTY. MAIN CONCERN TODAY WILL BE AN UPPER LEVEL DISTURBANCE THAT IS EMBEDDED UNDER THE RIDGE...WHICH CAN BE SEEN CURRENTLY KICKING OFF CONVECTION OVR NM. THIS WILL PROPAGATE THRU WRN CO THIS MORN. MAIN LIFT AND FOCUS FOR CONVECTION WILL BE LATER TODAY OVER KS...SO BELIEVE THAT THE BIGGEST IMPACT FROM THE DISTURBANCE WILL BE MOSTLY E OF OUR CWA. HOWEVER...WILL STILL SEE SCT STORMS DEVELOP EARLY TODAY OVER THE MTS...SPREADING TO THE I-25 CORRIDOR LATE IN THE AFTERNOON. SO...WILL STILL HAVE TO KEEP A CLOSE EYE OUT ON THE BURN SCARS EVEN THOUGH THE INTENSITY AND COVERAGE OF STORMS LOOKS A BIT LESS. FOR THE FAR ERN PLAINS...NR THE KS BORDER...THERE COULD BE MORE VIGOROUS CONVECTION...INCLUDING THE POTENTIAL FOR A STRONG STORM OR TWO...BUT BELIEVE THAT MOST OF THE HEAVY RAIN IMPACT WILL STAY FAR ENOUGH E TO PRESENT A SMALLER RISK FOR THE RIVERS. HAVE ALREADY ISSUED A COUPLE FLOOD WARNINGS FOR THE ARKANSAS AND PURGATOIRE...BUT THESE SPOTS SHOULD CREST AND BEGIN TO RECEDE LATER THIS MORNING. EXTENSIVE MID AND HIGH CLOUDS WILL CONTINUE TO LIMIT TEMPS TODAY...BUT WITH THE RIDGE BUILDING A BIT IT SHOULD BE A COUPLE DEGREES WARMER FOR MOST SPOTS THIS AFTERNOON. HIGH CLOUDS WILL THICKEN UP A BIT OVERNIGHT ESPECIALLY FOR THE NRN AND WRN PORTIONS OF THE CWA...LEADING TO ANOTHER MILD NIGHT. ROSE .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 355 AM MDT MON AUG 5 2013 ...WEDNESDAY COULD BE A RATHER WET AND STORMY DAY... NOT MUCH OVERALL CHANGE IN THE GUIDANCE. AS HAS BEEN STATED OVER THE LAST SEVERAL DAYS...THE MONSOON PLUME WILL REMAIN IN PLACE OVER THE FCST AREA THROUGH THIS FCST PERIOD...AND THIS PATTER N WILL KEEP THE REGION RATHER WET WITH SEASONABLE TEMPERATURES. THE MAIN DAY OF CONCERN APPEARS TO BE WEDNESDAY. NEARLY ALL SIMULATIONS ARE SHOWING THIS DAY IS LIKELY GOING TO BE WET...AND WE WILL LIKELY SEE OUR BEST CHANCE OF HEAVY RAINS OVER THE REGION. QUITE A FEW AREAS HAVE HAD DECENT RAINFALL IN THE LAST WEEK OR SO...SO FLASH FLOODING CONCERNS ARE GOING TO BE MORE WIDESPREAD WITH THIS EVENT (JUST NOT THE BURN SCARS). SIMULATIONS CONTINUE TO INDICATE SEVERAL FEATURES WILL COME INTO PLAY TO BRING THE THREAT OF HEAVY RAIN WEDNESDAY. FIRST...A COOL FRONT WILL MOVE IN TUESDAY NIGHT...BRINGING ANOTHER SURGE OF LLVL MOISTURE INTO THE REGION. THE UPPER LEVEL MONSOON PLUME WILL CONTINUE OVER THE REGION ADDING TO THE MOISTURE ALOFT. ADDITIONALLY...A WELL DEFINED DISTURBANCE WILL MOVE ACROSS THE REGION DURING THE DAY WEDNESDAY...AND THIS FEATURE WILL CREATE FAVORABLE DIFFLUENCE ALOFT TO ACCENTUATE THE UPWARD VERTICAL VELOCITY FIELDS OVER THE REGION. ALL THESE FEATURES COMING TOGETHER SHOULD ALLOW FOR HEAVY CONVECTIVE PRECIP WED. THE ONLY CONCERN I SEE FOR WED IS THAT CAPE MAY BE LIMITED AS IT MAY BE QUITE CLOUDY AND COOL...AND WITH LIMITED INSOLATION...CAPE VALUES MAY NOT GET TOO HIGH. IF WE DO SEE SOME SUN THEN THE THREAT OF HEAVIER RAIN WILL INCREASE. THERE IS ALSO A CHANCE THE CONVECTION MAY BE SEVERE ON THIS DAY (ESPECIALLY IF WE CAN GET SOME DECENT CAPE) AS SHEAR WILL BE MARGINAL FOR ROTATING STORMS. WITH THE LIKELY LOW LCLS...A FEW WEAK SUPERCELL TORNADOES WILL BE POSSIBLE. WRT TO THE NDFD GRIDS...I HAVE LIKELY POPS OVER THE MTNS WED WITH HIGH SCTD POPS ON THE PLAINS. I MENTIONED HEAVY RAIN (R+) IN THE WEATHER GRIDS. IT IS TOO EARLY TO MENTION SVR IN THE NDFD. IN THE MEANTIME...TUESDAY WE WILL SEE SCATTERED STORMS OVER THE MTNS WITH SCTD ACTIVITY MOVING ONTO THE PLAINS LATE IN THE DAY. TUESDAY NIGHT THE COOL FRONT WILL MOVE DOWN...AND I CANNOT RULE OUT SOME LOCALLY HEAVY RAIN THIS EVENING/NIGHT AS AN MCS MAY FORM ON THE SE PLAINS. WEDNESDAY WILL BE BUSY AS ALLUDED TO ABOVE. THURSDAY INTO THE WEEKEND CONTINUES TO LOOK BUSY. UPSLOPE WILL CONTINUE IN THE LLVLS AND MSTR WILL CONTINUE ALOFT WITH THE PERSISTENT SW MONSOON FLOW. NO WELL DEFINED SHORT WAVES ARE EXPECTED...BUT THERE WILL BE ENOUGH FORCING/INSTABILITY TO CONTINUE THE THREAT OF AFTERNOON AND EVENING SHOWER AND STORMS OVER THE ENTIRE REGION. SOME OF THE RAIN WILL BE LOCALLY HEAVY. /HODANISH && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 355 AM MDT MON AUG 5 2013 MAIN CONCERNS WILL BE POTENTIAL FOR STORMS LATER TODAY...ALONG WITH SOME LOCALIZED AREAS OF LOW CIGS AND EVEN SOME PC FG. MOST OF THE LOW CIGS WILL STAY E OF THE KS BORDER THIS MORNING...ALTHOUGH KALS COULD SEE SOME BRIEF LOW CLOUDS OR BR DUE TO THE OVERNIGHT RAINFALL IN THE SAN LUIS VALLEY. SCT TS SHOULD GET GOING FAIRLY QUICKLY TODAY OVER THE CENTRAL AND SW MTS...BUT MOST OF THE HEAVIER PRECIP SHOULD REMAIN OVER THE HYR TRRN. A FEW STORMS MIGHT SURVIVE TO THE VC OF KCOS AND POSSIBLY KPUB AFTER 21Z TODAY. ROSE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ROSE SHORT TERM...ROSE LONG TERM...HODANISH AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1003 AM EDT MON AUG 5 2013 .SYNOPSIS... A WEAK BACKDOOR COLD FRONT WILL BECOME NEARLY STATIONARY ACROSS SOUTHERN GEORGIA TODAY...THEN LINGER INTO MID WEEK BEFORE DISSIPATING AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL LATE IN THE WEEK INTO THE WEEKEND...BEFORE ANOTHER BACKDOOR COLD FRONT AFFECTS THE AREA LATE IN THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MID-MORNING SURFACE ANALYSIS SHOWS THE BACKDOOR COLD FRONT HAS BECOME STATIONARY SOUTH OF THE ALTAMAHA RIVER WITH A COOL EAST/NORTHEAST FLOW PREVAILING ACROSS THE AREA. SHOWERS ARE BEGINNING TO BREAKOUT ALONG PORTIONS OF NORTH COASTAL GEORGIA AHEAD OF WHAT APPEARS TO BE THE 850MB COLD FRONT. HIGH RESOLUTION MODELS ARE SIMILAR IN DEVELOPING ADDITIONAL SHOWERS/TSTMS OVER THE NEXT FEW HOURS ACROSS MAINLY SOUTHEAST GEORGIA SOUTH OF I-16 COINCIDENT WITH THE STRONGEST 850MB CONVERGENCE AXIS. WILL INCREASE POPS TO 30 PERCENT IN THIS AREA THROUGH EARLY AFTERNOON WITH POPS DIMINISHING TO SLIGHT CHANCE LATER THIS AFTERNOON AS THE LATEST RAP SHOWS 850MB CONVERGENCE DIMINISHING WITH TIME. THE WEATHER LOOKS DRY FOR MUCH OF SOUTHEAST SOUTH CAROLINA TODAY. HIGHS WILL RANGE FROM THE MID 80S ACROSS THE CHARLESTON TRI-COUNTY AREA TO AROUND 90 ACROSS THE FAR SOUTHWEST ZONES. TEMPERATURES ALONG THE BEACHES OF CHARLESTON COUNTY WILL LIKELY ONLY TOP OUT IN THE LOWER 80S. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TONIGHT...ANY SHOWERS/STORMS WILL DIMINISH AND/OR PUSH FARTHER INLAND LEADING TO A RATHER DRY NIGHT WITH LOWS AROUND 70 INLAND AND MID/UPPER 70S NEAR THE COAST. TUESDAY AND TUESDAY NIGHT...A MID AND UPPER LEVEL RIDGE CENTERED OVER THE SOUTHERN PLAINS WILL EXPAND EASTWARD OVER THE REGION. MEANWHILE AT THE SURFACE...THE FORMER BACKDOOR COLD FRONT WILL REMAIN NEARLY STATIONARY IN THE VICINITY OF THE FLORIDA/GEORGIA BORDER AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTHEAST. ONSHORE LOW LEVEL TRAJECTORIES WILL ADVECT MOISTURE INTO THE AREA...ESPECIALLY ACROSS SOUTHEAST GEORGIA WHERE ITS CLOSER PROXIMITY TO THE STALLED FRONT FAVORS THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON. THE LACK OF DEEPER MOISTURE FARTHER TO THE NORTHEAST WILL RESULT IN LESS COVERAGE OF SHOWERS AND THUNDERSTORMS WITH SOME AREAS CLOSER TO THE SOUTH CAROLINA COAST POSSIBLY REMAINING RAIN-FREE. WITH THE LOSS OF DIURNAL HEATING ALL CONVECTION WILL DISSIPATE BY MID-EVENING OR SO. THE COOLER ONSHORE FLOW SHOULD ONLY ALLOW TEMPERATURES TO REACH HIGHS IN THE UPPER 80S TO AROUND 90 INLAND AWAY FROM THE COAST. LOWS TUESDAY NIGHT WILL ACTUALLY BE UNSEASONABLY COOL...IN THE UPPER 60S TO LOWER 70S. WEDNESDAY AND WEDNESDAY NIGHT...A WEAK SHORT WAVE DISTURBANCE WILL PASS MAINLY NORTH OF THE AREA ON WEDNESDAY...BUT CAUSE SOME WEAKNESS ALONG THE EASTERN PERIPHERY OF THE MID AND UPPER LEVEL RIDGE. AT THE SURFACE...HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE NORTHEAST AS THE STALLED FRONT TO THE SOUTH DISSIPATES. DESPITE THE PASSAGE OF THE DISTURBANCE...MODELS ARE IN FAIRLY GOOD AGREEMENT SHOWING LITTLE IN THE WAY OF CONVECTION OVER THE AREA. THE FORECAST WILL INDICATE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER SOUTHEAST GEORGIA AND FAR SOUTHERN SOUTH CAROLINA DURING THE AFTERNOON...MAINLY BECAUSE THE DEEPEST MOISTURE WILL REMAIN OVER THESE AREAS. DAYTIME HIGHS WILL REMAIN IN THE UPPER 80S TO AROUND 90...WITH LOWS WEDNESDAY NIGHT AROUND 70 OR IN THE LOWER 70S INLAND FROM THE BEACHES. THURSDAY...THE MID AND UPPER LEVEL RIDGE WILL EXPAND AND BECOME WEST-EAST ORIENTED OVER THE REGION AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE WESTERN ATLANTIC. THIS IS A MORE TYPICAL SUMMERTIME PATTERN...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED TO OCCUR ALONG AND AHEAD OF THE SEA BREEZE IN THE AFTERNOON AND EARLY EVENING. TEMPERATURES WILL WARM AS THE FLOW BECOMES MORE SOUTHERLY...WITH HIGHS IN THE LOWER 90S AWAY FROM THE COAST. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... MEDIUM RANGE GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH MOST OF THE LONG TERM PERIOD...LEADING TO A HIGHER THAN NORMAL CONFIDENCE FORECAST. AN EXPANSIVE UPPER LEVEL RIDGE WILL PREVAIL OVER THE REGION THROUGH SATURDAY...BEFORE A LONG WAVE TROUGH EXPANDS ACROSS THE EASTERN U.S. LATE IN THE WEEKEND INTO EARLY NEXT WEEK. AT THE SURFACE...ATLANTIC HIGH PRESSURE WILL PREVAIL INTO THE WEEKEND...THEN A BACKDOOR COLD FRONT APPEARS POISED TO AFFECT THE AREA LATE SUNDAY AND MONDAY. CONVECTION WILL BE DIURNALLY DRIVEN THROUGH SATURDAY...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED ALONG AND AHEAD OF THE SEA BREEZE EACH AFTERNOON AND EARLY EVENING. THE PROBABILITY OF SHOWERS AND THUNDERSTORMS SHOULD INCREASE LATE IN THE WEEKEND INTO EARLY NEXT WEEK IN ASSOCIATION WITH THE BACKDOOR COLD FRONT. TEMPERATURES SHOULD BE NEAR NORMAL THROUGH MOST OF THE LONG TERM...WITH THE WARMEST TEMPERATURES LIKELY COMING SATURDAY WITH SOME COMPRESSIONAL HEATING AHEAD OF THE FRONT. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... MOSTLY VFR CONDITIONS EXPECTED THROUGH 12Z TUESDAY AT BOTH KCHS AND KSAV. ISOLATED SHOWERS AND THUNDERSTORMS COULD IMPACT THE TERMINALS...ESPECIALLY AT KSAV...BUT WOULD LIKELY BE BRIEF AND CONFIDENCE IS NOT HIGH ENOUGH TO MENTION AT THIS TIME. EASTERLY WINDS WILL INCREASE UPWARDS OF AROUND 15 KT THIS AFTERNOON...MAINLY AT KSAV...WITH A FEW HIGHER GUSTS POSSIBLE AS THE GRADIENT TIGHTENS OVER THE AREA. SOME LOWER CEILINGS ARE POSSIBLE AT KSAV LATE TONIGHT AS LOW LEVEL MOISTURE POOLS IN THE VICINITY OF THE STALLED FRONT TO THE SOUTH...BUT WILL KEEP CONDITIONS VFR UNTIL CONFIDENCE INCREASES. EXTENDED AVIATION OUTLOOK...ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON/EARLY EVENING AND COULD RESULT IN BRIEF REDUCTIONS IN CEILINGS/VISIBILITIES. OTHERWISE...VFR CONDITIONS ARE EXPECTED TO PREVAIL. && .MARINE... TODAY...A BACKDOOR COLD FRONT NEAR THE SAVANNAH RIVER WILL PUSH SOUTHWARD LEADING TO A SURGE OF EAST/NORTHEAST WINDS...AS HIGH AS 15-20 KT AT TIMES OVER THE SC WATERS. SEAS WILL RESPOND A BIT AS WELL BUT SHOULD STAY 4 FT OR LESS...HIGHEST OFFSHORE. THUS...NO ADVISORIES ARE EXPECTED. TONIGHT...MAINLY EAST WINDS EXPECTED AOB 15 KT AS HIGH PRESSURE REMAINS NORTH OF THE AREA WITH LOW PRESSURE TO THE SOUTH. TUESDAY THROUGH SATURDAY...A BACKDOOR COLD FRONT WILL STALL JUST SOUTH OF THE WATERS INTO WEDNESDAY BEFORE DISSIPATING...MAINTAINING AN ONSHORE FLOW ACROSS THE WATERS. THE FLOW WILL VEER SOUTHERLY LATER IN THE WEEK AS HIGH PRESSURE BUILDS IN FROM THE WESTERN ATLANTIC. IN GENERAL...WINDS SHOULD REMAIN AT OR BELOW 15 KT...HIGHEST NEAR SEABREEZE CIRCULATIONS ALONG THE COAST. SEAS WILL RANGE BETWEEN 1-3 FT...HIGHEST OVER OUTER GEORGIA WATERS. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ ST
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1055 AM EDT MON AUG 5 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 403 AM EDT MON AUG 5 2013 HIGH PRESSURE WILL REMAIN IN CONTROL ACROSS THE AREA TODAY AS IT MOVES EASTWARD. VERY WEAK DISTURBANCES IN THE PREVAILING NORTHWEST FLOW ALOFT COULD POTENTIALLY SPARK A SHOWER OR STORM TONIGHT...WITH CHANCES INCREASING TOWARD MIDWEEK AS A FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST AND MOVES THROUGH THE AREA. DRY WEATHER AND COOL TEMPERATURES RETURN ONCE AGAIN FOR THE COMING WEEKEND AS ANOTHER DOME OF HIGH PRESSURE SETTLES OVER THE AREA. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1055 AM EDT MON AUG 5 2013 RADAR MOSAIC SHOWS SHOWERS AND THUNDERSTORMS ACROSS NORTHWEST ILLINOIS THAT ARE HEADED SOUTHEAST. CURRENTLY SATELLITE SHOWS MOSTLY CLEAR SKIES ACROSS MUCH OF THE AREA WITH CLOUDS ACROSS NORTHERN ILLINOIS HEADING SOUTHEAST TOWARD CENTRAL INDIANA. RAP AND HRRR SHOW THE AFOREMENTIONED STORMS EITHER STAYING JUST NORTH OF THE FORECAST AREA OR CLIPPING A FEW OF THE NORTHERN COUNTIES. LOOKING AT THE CURRENT MOVEMENT AND LOCATION OF HIGH SURFACE PRESSURE THINK THERE/S AN OUTSIDE CHANCE STORMS COULD SNEAK INTO THE FAR NORTHERN PARTS OF THE AREA LATE THIS AFTERNOON...SO ADDED A SLIGHT CHANCE FOR THUNDERSTORMS THERE FROM 4 PM ON. GOING HOURLY TEMPERATURES ARE ON TRACK FOR FORECAST HIGHS IN THE LOW 80S SO LEFT THEM ALONE. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... ISSUED AT 403 AM EDT MON AUG 5 2013 WILL CONTINUE TO CARRY POPS TONIGHT...BUT SLIGHT CHANCE TO LOW CHANCE AT BEST AS SUPPORT IS WEAK. MODELS HAVE EVEN BACKED OFF OF POTENTIAL FOR TUESDAY...BUT WITH BUFKIT SHOWING SOME MODEST CONVECTIVE INSTABILITY WILL CARRY A 30 POP FOR THUNDERSTORMS. HIGHER POPS REMAIN MERITED...BUT CANNOT GO LIKELY ANY PERIOD OWING TO CONTINUED DIFFERENCES BETWEEN MODELS AND RUN TO RUN INCONSISTENCIES WITH THE RELATIVELY WEAK DISTURBANCES MOVING THROUGH THE AREA. HIGHEST POPS WILL OF COURSE BE WITH THE POTENTIAL FRONT MOVING INTO THE AREA MIDWEEK. ON TEMPS...NEAR TO JUST ABOVE CONSENSUS NUMBERS APPEARS TO FIT BEST WITH 850 TEMP TRENDS ACROSS THE BOARD. && .LONG TERM /THURSDAY THROUGH SUNDAY/... ISSUED AT 249 AM EDT MON AUG 5 2013 ECMWF AND GFS CONTINUE TO INDICATE A COOL NORTHWEST FLOW ALOFT WITH FEW TO NO SHORT WAVE DISTURBANCES PASSING THROUGH THE FLOW INTO THE OHIO VALLEY. AT THE SURFACE A WEAK COLD FRONT IS EXPECTED TO BE PUSHING THROUGH AND EXITING THE AREA ON THURSDAY AND FRIDAY. BY FRIDAY AFTERNOON STRONG SURFACE HIGH PRESSURE LOOKS TO BE IN PLACE PROVING ANOTHER DRY WEEKEND WITH ANOTHER ROUND OF BELOW NORMAL TEMPERATURES. && .AVIATION /DISCUSSION FOR THE 051500Z TAF UPDATE/... ISSUED AT 1033 AM EDT MON AUG 5 2013 FORECASTS IN GREAT SHAPE THIS MORNING. ONLY CHANGE WAS TO SLOW DOWN ARRIVAL OF THICKER MID LEVEL CLOUDS INTO THE EARLY AFTERNOON BASED ON CURRENT VIS SATELLITE. 12Z DISCUSSION FOLLOWS. AFTER SOME MORNING FOG...A QUICK RETURN TO VFR CONDITIONS IS EXPECTED FOR MUCH OF THIS TAF PERIOD. DIURNAL FOG AND LOW DEW POINT DEPRESSIONS WILL LINGER AT HUF...BMG AND LAF THIS MORNING. ONCE MIXING RESUMES A QUICK RETURN TO VFR IS EXPECTED AS FOG IS LOST. FORECAST SOUNDINGS TODAY SHOW REACHABLE CONVECTIVE TEMPS WITH CCL/S NEAR 4KFT. THUS HAVE TRENDED TOWARD SOME CU VFR CU THIS LATE THIS MORNING AND THIS AFTERNOON. A QUICK MOVING SHORT WAVE WILL APPROACH THE GREAT LAKES TONIGHT...BUT BEST MOISTURE AND FORCING WILL REMAIN NORTH OF THE TAF SITES. FORECAST SOUNDINGS AND TIME HEIGHT INDICATE SOME VFR CIGS ASSOCIATED WITH THIS FEATURE AS IT PASSES...AND THIS APPROACH SEEMS BEST. CLOUDS WITH THE PASSING SYSTEM SHOULD ALSO PREVENT ANY FOG OVERNIGHT. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...NIELD NEAR TERM...CP SHORT TERM...NIELD LONG TERM....PUMA AVIATION...JP/RYAN VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
646 AM CDT MON AUG 5 2013 .SYNOPSIS... ISSUED AT 348 AM CDT MON AUG 5 2013 LATEST SFC ANALYSIS WAS INDICATING DEPARTING HIGH PRESSURE CENTERED OVER LOWER MI INTO NORTHWESTERN OH...WHILE RETURN FLOW CONTINUED TO ORGANIZE UP THE PLAINS AND JUST EAST OF THE MO RVR VALLEY. UPPER 60 TO AROUND 70 SFC DPTS WERE WRAPPING UP AROUND THE WESTERN FLANK OF THE RIDGE FROM THE LOWER MS RVR VALLEY...UP ACRS NEB. CURRENT MESOANALYSIS WAS INDICATING ELEVATED PLUME OF HIGHER THTA-E AIR GENERALLY ACRS THE SAME REGIONS...MAYBE GETTING PUSHED A BIT FURTHER EAST AND NORTHEAST OF THE THE SFC LAYER ACRS THE WESTERN THIRD OF IA. ALOFT...NORTHWEST FLOW CONTINUED WITH AN EMBEDDED WAVE PUSHING ACRS NORTHWESTERN INTO WEST CENTRAL MN DRIVING MAINLY AN ELEVATED MCS ACRS THE SOUTHEAST HALF OF MN. THIS ACTIVITY DROPPING SOUTHEAST ALONG THTA-E GRADIENT AND SHOULD MAKE IT INTO THE NORTHWESTERN AND NORTHERN PORTIONS OF THE DVN CWA THIS MORNING...POSSIBLY INDEPENDENCE BY 1030Z. OTHER STRONG THTA-E ADVECTION AND CONVERGENT FIELDS WERE FUELING HEAVY CONVECTIVE BANDS ACRS KS INTO SOUTHERN MO. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 348 AM CDT MON AUG 5 2013 TODAY...WILL WALK IN PORTION OF THE UPSTREAM MN/IA BORDER MCS INTO THE NORTHWESTERN TO NORTHERN THIRD OF THE DVN CWA THIS MORNING... BUT AS IT GETS AWAY FROM BETTER SUPPORT/H85 JET THTA-E FEED FEEL THE GENERAL WEAKENING TREND THAT THE LATEST RUN HRRR SUGGESTS WILL VERIFY AS IT SPILLS ALONG AND SOUTH OF HWY 30 AFTER 12Z THROUGH 14Z. BUT MAY STILL HAVE TO WATCH FOR A STRONG STORM IN THE FAR NORTHWESTERN CWA AS IT ARRIVES THOUGH AROUND 515 TO 530 AM CDT. WILL THEN WALK THE REST OF THE MCS AGAIN PROBABLY IN A DIURNALLY WEAKENING MODE ACRS THE NORTHERN THIRD OR A LITTLE MORE OF THE DVN CWA THROUGH LATE MORNING WITH HIGHEST POPS NORTH OF HWY 30. THEN AS CONVECTIVE DEBRIS CLEARS AND WARM AIR/THTA-E ADVECTION CONTINUE ACRS THE AREA INTO THE AFTERNOON...PORTIONS OF THE DVN CWA MAY BECOME RELATIVELY UNSTABLE ESPECIALLY THE SOUTHWESTERN HALF. REMNANT OUTFLOW BOUNDARIES AND A SECONDARY TYPE WARM FRONT MAY LAY OUT ACRS THE AREA AND ACT AS POTENTIAL FOCAL POINTS FOR AFTERNOON AND EARLY EVENING CONVECTION TO REFIRE ON. SOUTHERN PORTION OF THE NW MN WAVE AND RATHER VIGOROUS MID/UPPER JET STREAKS STREAMING ALONG AND JUST NORTH OF THE AREA COULD KICK OFF SCTRD STORMS THIS AFTERNOON WITH AN ISOLATED THREAT OF STRONG TO SVR STORMS LIKE SPC IS HINTING AT DUE TO INCREASING VERTICAL SHEAR PROFILES. BUT MUCH WILL DEPEND ON EVENTUAL HIGH TEMPS AROUND 80 OR WARMER AND IF SFC DPTS CAN MAKE IT AT LEAST INTO THE UPPER 60S. WILL GO WITH LOW TO MODERATE CHC POPS THIS AFTERNOON BECAUSE OF COVERAGE/INSTABILITY CONCERNS. HIGHS COOLER IN THE MID TO UPPER 70S IN THE NORTHEASTERN THIRD...TO THE LOW TO MID 80S IN THE SOUTHWEST WITH INCREASING BOUNDARY LAYER HUMIDITY. TONIGHT...WITH THE WAVE/VORT MAX SHEARING OFF TO THE EAST OF THE AREA...END OF LIFTING MECHANISMS AND DIURNAL PROCESSES SHOULD BRING ABOUT A DECREASE OF ANY PRECIP ACTIVITY AS THE EVENING PROGRESSES. NOCTURNAL LLJ PROGGED TO FOCUS BACK TO THE WEST AND SOUTH OF THE AREA AS WELL. WITH HIGHER DPTS IN PLACE AND LIGHT VARIABLE FLOW... ANY CLOUD CLEAR OUT MAY FOSTER FOG PRODUCTION ESPECIALLY IN AREAS THAT MANAGE TO GET SOME NEEDED RAINFALL. FOR NOW WILL JUST BLANKET THE CWA WITH PATCHY LATE NIGHT FOG WORDING. LOWS IN THE MID TO UPPER 60S IN MOST OF THE LOCAL FCST AREA. ..12.. .LONG TERM...(TUESDAY THROUGH NEXT SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 A SHORT WAVE AND COOL FRONT MOVING OUT OF THE NORTHERN PLAINS TUESDAY AND THROUGH THE MID AND UPPER MISSISSIPPI VALLEY BY WEDNESDAY MORNING WILL BRING A CHANCE OF THE THUNDERSTORMS TO THE REGION. TEMPERATURES AHEAD OF THE FRONT SHOULD RISE INTO THE 80S WITH DEWPOINTS IN THE UPPER 60S AND LOW 70S. SURFACE BASED CAPES BY MID AFTERNOON ARE EXPECTED TO BE AROUND 2K J/KG OVER MOST OF THE AREA. WITH THE INSTABILITY IN PLACE AND SOME WEAK UPPER FORCING SPREADING IN AHEAD OF THE MAIN SHORTWAVE...SOME ISOLATED TO SCATTERED STRONG STORMS WILL BE POSSIBLE DURING THE AFTERNOON AND HAVE INCLUDED SLIGHT CHANCE TO LOW CHANCE POPS FOR THE ENTIRE AREA AFTER 18Z. THE MAIN FORCING IS PROGGED TO MOVE THROUGH LATE TUESDAY NIGHT AND HAVE KEPT HIGH CHANCE TO LIKELY POPS DURING THIS PERIOD. THERE SHOULD BE ENOUGH INSTABILITY WITH MODERATE DEEP LAYER SHEAR FOR A RISK OF SEVERE STORMS OVERNIGHT. THE FRONT AND UPPER WAVE WILL BE EAST OF THE AREA BY WEDNESDAY MORNING BUT THE LOW LEVEL MOISTURE WILL BE SLOW TO LEAVE IN THE WEAK FLOW BEHIND THE FRONT SO HELD ON TO SOME LOW POPS EAST AND SOUTH WEDNESDAY. FOR THE REST OF THE FORECAST PERIOD NORTHWEST FLOW WILL REMAIN IN PLACE KEEPING MAINLY DRY AND COOLER THAN NORMAL CONDITIONS OVER THE AREA. THE MODELS ARE SHOWING A COUPLE OF WAVES MOVING OUT OF THE SOUTHERN ROCKIES AND THROUGH THE MID AND LOW MISSISSIPPI VALLEY WEDNESDAY THROUGH FRIDAY. THE NORTHERN EDGE OF THE PRECIPITATION BRUSHES THE FAR SOUTHERN COUNTIES SO KEPT SOME SLIGHT CHANCE POPS GOING IN THE SOUTH MID TO LATE WEEK. BROAD BRUSH SLIGHT CHANCE POPS WERE PLACED OVER THE FORECAST AREA FOR SUNDAY WITH THE ECMWF SHOWING A SHORT WAVE MOVING OUT OF THE NORTHERN PLAINS INTO THE UPPER MS VALLEY SUNDAY AND SUNDAY NIGHT. DLF && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 632 AM CDT MON AUG 5 2013 CURRENT STORM CLUSTER AFFECTING CID...DBQ AND POSSIBLY MLI THROUGH 15Z THIS MORNING. SOUTHWEST FLOW 3-5K FT AGL ALOFT AT 20 KTS PRODUCING SOME MODERATE TURBULENCE IN THE LOWER LEVELS AROUND THE SHOWERS/STORMS. AFTER THE PRECIP CLEARS THIS MORNING...A PERIOD OF LOW VFR TO MVFR STRATOCU AT BKN TO OVC COVERAGE UNTIL THE AFTERNOON WHEN CIGS ARE EXPECTED TO LIFT TO VFR AND MORE SCTRD BREAKS. ISOLATED TO WDLY SCTRD SHOWERS AND THUNDERSTORMS MAY POP UP AGAIN IN THE AFTERNOON IN THE VCNTY OF ALL TERMINALS BUT MORE LIKELY ALONG AND NORTH OF I80. SOUTH TO SOUTHWEST SFC WINDS OF 7-12 KTS. HIGHER LEVELS OF SFC MOISTURE MAY COMBINE WITH CLEARING SKIES TONIGHT AND LIGHT WINDS TO PRODUCE AREAS OF FOG AFTER 05Z TUE. COVERAGE AND DENSITY STILL UNCERTAIN AT THIS TIME BUT WILL INCLUDE AT LEAST MVFR LEVEL FOG IN THE TAFS FOR NOW. ..12.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...12 SHORT TERM...12 LONG TERM...DLF AVIATION...12
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
617 AM CDT Mon Aug 5 2013 ...UPDATED AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 451 AM CDT MON AUG 5 2013 Light southeast surface winds were prevalent across the area this morning with anomalously high dew points around 70 degrees across most of central and sw Kansas. Dew point depression have decreased to a few degrees in the extreme southwest to zero in parts of central Kansas. Stratus had developed overnight across most of the region and dense fog development appeared to be accelerating across central Kansas as well from areas around Great Bend to Pratt. On the larger scale, the 850 mb analysis indicated a large area of 850 mb dew points in excess of 18 degrees c across the central high plains. The mesoanalysis also indicated precipitable water values exceeding 1.5 inches across a large portion of western Kansas. && .SHORT TERM...(Today and tonight) ISSUED AT 451 AM CDT MON AUG 5 2013 Today`s forecast will be a challenge on several fronts, including this morning`s low stratus and fog, followed by warm temperatures today, the onset of any afternoon convection as well as heavy rain and flooding potential later tonight. The fog advisory will remain intact as visibilities continue to deteriorate across central Kansas. Locations along and east of highway 283 appear to have the greatest chances for dense fog development through the early morning. the fog should dissipate as temperatures warm through the mid morning hours. Models warm temperatures into the upper 90s to around 100 degrees in the extreme southern counties. A warm frontal boundary should lift northward, aiding surface dew points to mix out to slightly lower values across the far southern areas. Higher relative HUMIDITIES will be likely across the hays to Pratt regions. There will be severe weather chances later this afternoon. Large hail and damaging wind will be possible late in the day into this evening and severe watches are probable for portions of western Kansas especially if a warm frontal zone/surface wind shift develops in the vicinity of the larger surface low feature across eastern Colorado and west central Kansas. Given the water loaded nature of any supercells, wet macroburst type wind events may be the greatest threat in addition to golf ball sized or larger hail. Localized flash flooding may also develop if storms train over the same areas later this evening. Although a flood watch was considered, given less certainty in storm motions and speeds and greatest threat location, we will not issue a flood watch at this time. .LONG TERM...(Tuesday through Sunday) ISSUED AT 339 AM CDT MON AUG 5 2013 Upper level high that was located over the panhandle of Texas earlier this morning will slowly drift southeast across central Kansas early next week. As this upper high moves south the upper level ridge axis located across the Rockies will weaken as an upper level trough drops out of central Canada and into the northern plains. Tuesday night and early Wednesday a cold front will drop south across the central plains as the northern plains upper level trough moves into the western great lakes. As this cold front move south across western Kansas Tuesday night the precipitation chances will once again improve. Not only with there be a chance for thunderstorms with the frontal passage Tuesday night, but also given the upslope flow and moisture forecast by the ECMWF and GFS behind this front there will also be high chance to likely chances for convection Wednesday night and/or Thursday as an upper level trough exits the Rockies and moves across the central high plains. Timing appears to be an issue on this next more significant upper level trough have decided to stay close to the previous forecast but trend precipitation chances up on Wednesday night and Thursday. Warm 925-850mb temperatures ahead of the cold front on Tuesday continues to support highs near 100 degrees for at least southwest and south central Kansas. Behind the front 850mb temperature trends from the ECMWF and GFS suggest at least a 6c to 8c drop between 00z Wednesday to 00z Thursday. This combined the potential for some clouds and possible precipitation continues to support highs mainly in the low to mid 80s on Wednesday. mid to upper 70s for highs not out of the question across north central and west central Kansas if the cloud cover and ECMWF and NAM 925-850mb temperatures at 18z Wednesday and 00z Thursday are correct. Temperatures will then begin to warm Friday into the weekend period as the surface boundary lifts back north as a warm front. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) ISSUED AT 614 AM CDT MON AUG 5 2013 LIFR conditions can be expected at all three taf sites early this morning given light southeast winds, and low level moisture present across western Kansas. Bufr soundings and HRRR both were in decent agreement with the vsby improving quicker than the status and VFR conditions will develop by 15z at DDC and GCK. VFR conditions are expected at HYS by 17z. Scattered late day thunderstorms will be possible near a warm front that is expected to be located between DDC and HYS late this afternoon. Convection will increase in areal coverage early tonight so introduce thunderstorms into all three tafs after 00z. && .PRELIMINARY POINT TEMPS/POPS... DDC 98 70 96 67 / 20 60 50 50 GCK 98 69 94 66 / 20 70 50 50 EHA 98 70 96 65 / 20 40 40 30 LBL 100 70 98 67 / 20 50 40 40 HYS 91 70 92 68 / 30 90 50 40 P28 99 73 99 72 / 10 60 50 40 && .DDC WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY until 9 AM CDT /8 AM MDT/ this morning FOR KSZ030-031-043>046-061>066-075>081-086>090. && $$ SYNOPSIS...RUSSELL SHORT TERM...RUSSELL LONG TERM...BURGERT AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1153 AM EDT MON AUG 5 2013 LATEST UPDATE... UPDATE .SYNOPSIS... ISSUED AT 334 AM EDT MON AUG 5 2013 CLOUDS WILL BE ON THE INCREASE THIS MORNING...AND RAIN WILL SPREAD IN ACROSS THE AREA THIS AFTERNOON AND EARLY THIS EVENING. RAIN IS THEN EXPECTED TO REMAIN OVER THE AREA FOR A GOOD PORTION OF THE NIGHT TONIGHT. THERE WILL BE A LOW CHANCE OF A THUNDERSTORM TONIGHT...HOWEVER MOST AREAS WILL NOT SEE ONE AND SEVERE WEATHER IS NOT EXPECTED. ANOTHER BETTER CHANCE OF SHOWERS AND STORMS WILL COME DURING THE TUESDAY NIGHT AND WEDNESDAY TIME FRAME AHEAD OF AND ALONG A COLD FRONT THAT WILL MOVE THROUGH THE AREA. DRIER AIR CAN BE EXPECTED FOR THE END OF THE WEEK. && .UPDATE... ISSUED AT 1153 AM EDT MON AUG 5 2013 BACKED OFF ON THE CHANCES FOR SHOWERS THIS AFTERNOON JUST A BIT. DRIER AIR IS WINNING THE BATTLE AT THE MOMENT WITH MUCH OF THE PRECIP DIMINISHING IN AREAL EXTENT AND INTENSITY AS TO MOVES INTO LOWER MI. THERE MAY BE A DECENT LULL THROUGH THE EARLY TO MID AFTERNOON HOURS. THE EXPECTATION IS THAT WE WILL SEE PRECIPITATION BECOME MORE WIDESPREAD IN THE LATE AFTERNOON THOUGH AND INTO THE EVENING HOURS. THE HRRR SHOWS A LITTTLE LESS PRECIPITATION THAN IT DID A FEW HOURS AGO BUT STILL SHOWS RAIN SHOWERS EXPANDING IN COVERAGE TOWARDS 00Z. SO...CHANCE TYPE POPS FOR RAIN SHOWERS INTO MID AFTERNOON BECOMING LIKELY TOWARDS EVENING. MODELS SHOW A GOOD INFLUX OF MOISTURE IN THE LOWER LEVELS WHICH IS WHY WE EXPECT PRECIP TO EXPAND LATER. 850MB MOISTURE TRANSPORT INCREASES AS DOES ISENTROPIC LIFT ON THE 305K SURFACE LATER THIS AFTERNOON. SOLID LIFT ON THE 305K SURFACE IS SEEN AT 00Z WITH CONDENSATION PRESSURE DEFICITS NEAR 0MB/S. SOME BREAKS IN THE OVERCAST WILL BE POSSIBLE THIS AFTERNOON. THE BREAKS COMBINED WITH A LITTLE LESS PRECIPITATION IS WHY WE HAVE NUDGED HIGH TEMPS UP SLIGHTLY IN ALL AREAS. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 334 AM EDT MON AUG 5 2013 THE TWO MAIN PERIODS OF CONCERN ARE RAIN CHANCES THIS AFTERNOON AND TONIGHT...AND THEN CONVECTIVE POTENTIAL TUE NIGHT AND WED. THE MAIN CHANGES TO THE FCST ARE AN INCREASE IN RAIN CHCS THIS AFTERNOON/ TONIGHT AND ALSO DROPPING TEMPS A BIT TODAY AS A RESULT OF THE HIGHER CONFIDENCE OF THE RAIN. AS MENTIONED ABOVE...CONFIDENCE HAS INCREASED A DECENT AMOUNT THAT MOST OF THE AREA WILL SEE A DECENT RAINFALL LATER THIS AFTERNOON AND TONIGHT. MOST OF THE MODELS HAVE FOLLOWED THE EURO IN BRINGING THE SHORT WAVE NOW ACROSS ERN NORTH DAKOTA AS OF 07Z TOWARD THE CWFA LATER TODAY AND TONIGHT. CONVECTION HAS BLOWN UP ACROSS SRN MN AS EXPECTED THIS MORNING AT THE NOSE OF THE LLJ/MOISTURE TRANSPORT JUST AHEAD OF THE WAVE. THE WAVE IS NOT EXPECTED TO LOSE ITS PUNCH AS QUICKLY...AND THE LLJ/MOISTURE TRANSPORT AXIS WILL SHIFT TO LAKE MICHIGAN BY 00Z. WE WILL LIKELY SEE THE SHOWERS OUT AHEAD OF IT TRAVEL VIA THE FAST MID LEVEL FLOW INTO THE AREA A BIT EARLIER AHEAD OF THE LLJ. IT APPEARS THAT RAIN WILL APPROACH THE COAST BY 18Z...AND SHOULD OVERSPREAD A GOOD MAJORITY OF THE CWFA BY 00Z TONIGHT. FOR THIS REASON...WE BELIEVE TEMPS WILL RISE QUICKLY TO AROUND 70 BY THE TIME THE RAIN MOVES IN...BEFORE FALLING ONCE THE RAIN GET HERE. THE INSTABILITY DOES NOT FOLLOW AS QUICKLY...AND WEAKENS BY THE TIME IT GETS HERE AFTER 03Z TONIGHT AS THE SHORT WAVE BEGINS TO ENTER THE AREA. EVEN WHEN IT DOES ARRIVE...IT WILL LIKELY ONLY PRODUCE ISOLATED STORMS AS LI/S ARE JUST A TOUCH BELOW ZERO C. DUE TO THE LACK OF INSTABILITY BOTH AT THE SFC AND ALOFT...WE DO NOT EXPECT ANY SEVERE WEATHER EVEN WITH GOOD SHEAR VALUES. THE RAIN SHOULD MOVE OUT BY 12Z TUE AS THE SHORT WAVE SHOULD BE READY TO EXIT THE CWFA BY THAT TIME. WE SHOULD SEE A RELATIVE LULL IN PCPN WITH SOME SHORT WAVE RIDGING EXPECTED IN THE WAKE. THE SFC FRONT WILL BE JUST SOUTHWEST OF THE AREA...AND WE COULD SEE WEAK SHORT WAVES IN THE FAST FLOW ALOFT POTENTIALLY TOUCH OFF ADDITIONAL SHOWERS AND STORMS. THE NEXT BEST CHC OF ADDITIONAL SHOWERS AND STORMS WILL COME DURING THE SECOND HALF OF TUE NIGHT AND WED MORNING ACROSS THE AREA. THIS WILL OCCUR AS A BETTER DEFINED SHORT WAVE IS EXPECTED TO DIVE SE OUT OF CANADA AND INTO THE UPPER MIDWEST TUE NIGHT. AHEAD OF THE SHORT WAVE...WE WILL SEE THE LLJ HELP TO FIRE CONVECTION TO OUR WEST NEAR THE QUAD CITIES AND THEN MOVE IN VIA THE MEAN WRLY FLOW ALOFT. IF THINGS EVOLVE THIS WAY...THIS SHOULD LIMIT THE CONVECTIVE/SEVERE POTENTIAL ON WED AS THE FRONT MOVES THROUGH AS IT WILL LIMIT THE HEATING AHEAD OF THE FRONT. CONVECTION WILL REMAIN POSSIBLE INTO WED AFTERNOON BEFORE THE FRONT EXITS BY 00Z THU. .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 334 AM EDT MON AUG 5 2013 THE THEME OF SLIGHTLY BELOW NORMAL TEMPERATURES WILL CONTINUE THROUGH NEXT WEEKEND AS THE PERSISTENT/LARGE VORTEX REMAINS OVER EASTERN CANADA. WILL GO WITH A DRY FORECAST ON WEDNESDAY NIGHT AND THURSDAY AS CURRENT INDICATIONS ARE THAT THE COLD FRONT WILL BE EAST OF THE AREA WITH HIGH PRESSURE BUILDING IN. THE UPPER LOW WHICH DROPS SOUTH TOWARD THE LAKE SUPERIOR REGION LATE IN THE WEEK SHOULD SEND ANOTHER COLD FRONT THROUGH LWR MI ON FRIDAY NIGHT. HOWEVER AHEAD OF THAT FRONT ON FRIDAY H8 TEMPS NEAR 15C TRY TO SNEAK IN. GIVEN ENOUGH SUNSHINE... WE COULD TOP 80 DEGREES FRIDAY AFTERNOON. WILL CARRY A SLIGHT CHANCE OF RAIN SHOWERS WITH THE COLD FRONT ON FRIDAY NIGHT... ALTHOUGH THE COLD AIR BEHIND IT DOES NOT APPEAR TO LINGER TOO LONG SINCE THE UPPER LOW LIFTS OUT OVER THE WEEKEND AND THE FLOW ALOFT GOES ZONAL AGAIN FOR A FEW DAYS. THAT IMPLIES THAT TEMPERATURES NEXT WEEKEND WILL NOT BE TOO MUCH BELOW NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 754 AM EDT MON AUG 5 2013 SHOWERS APPROACHING FROM WISCONSIN AND MINNESOTA SHOULD OVERSPREAD THE REGION FROM WEST TO EAST AFTER 18Z THIS AFTERNOON. FLIGHT CONDITIONS ARE EXPECTED TO REMAIN VFR WITH CIGS FALLING TO 4000-6000 FT AND VSBYS MOSTLY GREATER THAN 6 MILES AS THE SHOWERS ARRIVE. HOWEVER TONIGHT CONDITIONS SHOULD TREND DOWN INTO MVFR CATEGORY AFTER 03Z AS THE RAIN CONTINUES WITH THE WARM FRONT LIFTING NORTH TOWARD SRN LWR MI. SOME IFR IS ALSO POSSIBLE AFTER 06Z AS HIGHER DEW POINT AIR ASSOCIATED WITH THE WARM FRONT TRIES TO NUDGE IN FROM THE SOUTHWEST. TSTMS ARE VERY UNLIKELY TODAY INTO THE EARLY EVENING ALTHOUGH THAT CHANCE DOES CREEP UP TOWARD 06Z. DID NOT PUT ANY TSTMS IN THE TAFS AT THIS POINT BUT THIS WILL NEED TO BE MONITORED. && .MARINE... ISSUED AT 334 AM EDT MON AUG 5 2013 NO MARINE HEADLINES WILL BE REQUIRED WITH THIS FCST PACKAGE. AFTER A BREAK IN THE WINDS EARLY THIS MORNING...WINDS WILL COME BACK UP A BIT TODAY. THIS TIME THEY WILL HAVE A SRLY COMPONENT TO THEM...OUT AHEAD OF THE NEXT INCOMING SYSTEM. SOME LOCATIONS UP NORTH COULD INITIALLY SEE SOME WINDS UP TO 20 KNOTS. SRN LOCATIONS COULD THEN SEE SOME WINDS APPROACH 20 KNOTS TONIGHT AS THE LOW LEVEL JET PASSES ACROSS THOSE AREAS. WINDS WILL DIMINISH ON TUE...ONLY TO COME UP TUE NIGHT AND EARLY WED AHEAD OF THE NEXT FRONT. && .HYDROLOGY... ISSUED AT 334 AM EDT MON AUG 5 2013 WE ARE NOT EXPECTING ANY FLOODING AT THIS TIME...HOWEVER IT DOES LOOK LIKE THE AREA WILL SEE SOME BENEFICIAL RAINS THIS WEEK THROUGH WED. THE AREA OF RAINFALL EXPECTED THIS AFTERNOON AND TONIGHT ALMOST APPEARS TO BE A GOOD SOAKING RAIN. PRECIPITABLE WATERS COME UP A BIT TO AROUND 1.5 INCHES. THIS IS NOT ABNORMALLY HIGH FOR THIS TIME OF THE YEAR. WE ARE EXPECTING THAT MANY LOCATIONS WILL SEE UP TO 0.75 INCHES OF RAIN THROUGH TONIGHT. THE NEXT BATCH OF RAIN WOULD LIKELY BE TUE NIGHT AND WED AS THE NEXT FRONT APPROACHES THE AREA. RAIN AMOUNTS THEN ARE STILL A BIT UNCERTAIN...BUT SOME HEAVIER DOWNPOURS WILL BE POSSIBLE THEN WITH MORE CONVECTION POSSIBLE COMPARED TO TONIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ UPDATE...DUKE SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...MEADE AVIATION...MEADE HYDROLOGY...NJJ MARINE...NJJ
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
559 AM CDT MON AUG 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 330 AM CDT MON AUG 5 2013 A 30 KT LLJ NOSING UP INTO SW MN EARLY THIS MORNING HAS FORCED A FAIRLY BROAD SHIELD OF SHOWERS WITH EMBEDDED THUNDERSTORMS THAT HAS BEEN STEADILY MAKING ITS WAY ACROSS MN THIS MORNING. ELEVATED INSTABILITY HAS NOT MADE MUCH PROGRESS NE THOUGH...WHICH IS WHY ANY DEEPER CONVECTION HAS ESSENTIALLY BEEN CRAWLING AROUND THE MPX CWA BORDER WITH FSD. MOST OF THE HOPWRF MEMBERS ALONG WITH THE LOCAL MPX-WRF HAVE ALL DONE A DECENT JOB IN CAPTURING WHAT HAS HAPPENED SO FAR OVERNIGHT IN TERMS PRECIP PLACEMENT...THEY HAVE ALL JUST BEEN ABOUT 2 HOURS BEHIND SCHEDULE. AS A RESULT...WAS FAIRLY AGGRESSIVE WITH MOVING LIKELY OR BETTER POPS OUT OF THE AREA THIS MORNING. BASED ON CURRENT MOVEMENT...BACK EDGE OF THE SHOWERS OVER CENTRAL MN WILL BE CLEARING THE EAU AREA AROUND 11Z...SO CERTAINLY DOES NOT MAKE MUCH SENSE TO HAVE MUCH IN THE WAY OF POPS BEYOND 15Z. THE ONLY POTENTIAL PROBLEM FOR THIS FASTER PROGRESSION OF LOWER POPS THROUGH THE AREA IS THE FACT THAT THERE IS A SFC TROUGH/COLD FRONT FEATURE CURRENTLY MOVING THROUGH THE ERN DAKOTAS THAT THE HRRR IS TRYING TO DEVELOP ANOTHER LINE OF CONVECTION ALONG LATER THIS MORNING. HAVE SEEN A FEW SPECKLES ON THE RADAR TO THE WEST OF THE MAIN PRECIP SHIELD OVER WRN MN...BUT TO THIS POINT WE HAVE NOT SEEN ANYTHING TO SUGGEST STORMS ON THE ORDER OF THE WHAT THE 5Z AND 6Z VERSIONS OF THE HRRR HAVE BEEN SHOWING DEVELOPING NEAR THE MN/SD. WITH MAIN PUSH OF MOISTURE TRANSPORT FOLLOWING THE PRECIP SHIELD EAST AND WITH AT LEAST SOME DEGREE OF OVERTURNING OCCURRING WITH THE FIRST ROUND OF RAIN...HAVE FAVORED THE FASTER DEPARTURE OF PRECIP...THOUGH THIS MAY NEED TO BE CHANGED BEFORE RUNNING OUT THE DOOR AT 6 AM. FOR THIS AFTERNOON...BIG CHANGE TO THE FORECAST WAS TO BOOST HIGHS A FEW DEGREES...MAINLY OVER MN. BASED ON THE HOPWRF...ALONG WITH THE RAP...EXPECT SKIES TO OPEN UP PRETTY GOOD BY THIS AFTERNOON BEHIND THIS MORNINGS ACTIVITY. WITH H85 TEMPS IN THE NEIGHBORHOOD OF 16C...THIS WOULD FAVOR MIXING DOWN HIGHS INTO THE LOW TO MID 80S ACROSS MN. HELD HIGHS IN THE 70S ACROSS WI WHERE CLOUD COVER WILL BE MORE PERSISTENT. OF COURSE IF THE CLOUDS DO NOT CLEAR OUT AS PLANNED...THEN IT WILL BE A SECOND DAY IN A ROW WHERE CLOUDS RESULT IN A FORECAST THAT IS A BIT OVERDONE ON THE HIGHS.... FOR THIS AFTERNOON...THAT AFOREMENTIONED DAKOTAS THROUGH WILL MEANDER OVER TO NEAR THE MN/WI BORDER. THE GFS DEVELOPS UP TO 1000 J/KG OF MLCAPE OUT AHEAD OF THIS BOUNDARY...WHICH MAY BE ENOUGH TO GENERATE SOME ISO/SCT STORMS. HOWEVER...BEHIND THIS MORNINGS WAVE...ALL MODELS SHOW SOME PRETTY EXTENSIVE DRYING AND SUBSIDENCE IN THE MID-LEVELS. NAM/RAP SOUNDINGS SHOW A DECENT SUBSIDENCE INVERSION DEVELOPING AROUND H7 AS WELL. ALL OF THIS POINTS TO WHAT SHOULD BE A DRY DAY...THOUGH WITH INSTABILITY FORECAST TO BE IN PLACE...CAN NOT COMPLETELY RULE OUT SOME DIURNALLY DRIVEN THUNDERSTORM ACTIVITY DEVELOPING...SO HAVE LEFT SOME 20-30 POPS IN PLACE THIS AFTERNOON FOR ERN MN INTO WRN WI. FOR TONIGHT...THE MPX AREA LOOKS TO BE CAUGHT BETWEEN AREAS OF FORCING FOR PRECIP...WITH CURRENT PRECIPITATION HEADING FOR MICHIGAN AND THE FRONT FOR TUESDAY AFTERNOON REMAINING FAR ENOUGH NW TO KEEP THE AREA DRY. AT THE MOMENT...EXPECT MAINLY CLEAR SKIES TONIGHT...WITH LIGHT AND VARIABLE WINDS. WITH DEWPS UP IN THE UPPER 50S TO MID 60S...THIS COULD LEAD TO SOME POCKETS OF FOG DEVELOPING OVERNIGHT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 330 AM CDT MON AUG 5 2013 THE MAIN FORECAST CONCERN DURING THE TUESDAY THROUGH SUNDAY PERIOD WILL BE THE CHANCES FOR SHRA/TSRA TUESDAY AFTERNOON INTO TUESDAY NIGHT AS A COLD FRONT MOVES THROUGH THE REGION. THE REMAINS SOME VARIABILITY IN THE TIMING AND ORIENTATION OF THE FRONT AMONGST THE GFS... NAM... ECMWF... AND SREF... WITH THE NAM BEING FASTEST AND ECMWF BEING SLOWEST. A SHORTWAVE ROTATING EAST FROM THE NORTHERN ROCKIES WILL HELP DRIVE THE FRONT ACROSS THE AREA WHILE THE MAIN UPPER TROUGH DROPS SOUTH FROM CANADA. LARGE SCALE FORCING IN TERMS OF UPPER DIVERGENCE AND DPVA LOOK SUFFICIENT FOR FAIRLY WIDESPREAD PCPN TO OCCUR ALONG/AHEAD OF THE FRONT... WITH THALER QG DIAGNOSTICS DEPICTING AN ELONGATED AREA OF GOOD 700MB OMEGA FROM WESTERN LAKE SUPERIOR INTO NORTHWEST IOWA BY 00Z WEDNESDAY. THIS SHOULD BE MORE THAN SUFFICIENT TO GET SHRA/TSRA GOING DURING THE AFTERNOON HOURS AS THE FRONT MOVES THROUGH THE AREA. THE QUESTION THEN BECOMES WHETHER OR NOT ANY SEVERE WEATHER CAN BE EXPECTED. THE NEW DAY 2 OUTLOOK FROM SPC DOES INCLUDE A SLIGHT RISK ACROSS MOST OF THE AREA... ESSENTIALLY NEAR AND SOUTH OF I-94. IT LOOKS LIKE WE/LL HAVE ANYWHERE FROM 1000-2000 J/KG OF MLCAPE WITH WHICH TO WORK... ALONG WITH DEEP LAYER SHEAR AOA 40 KT... SO SOME ORGANIZED CONVECTION IS CERTAINLY POSSIBLE. DEEP LAYER SHEAR WILL BE SUFFICIENT FOR SUPERCELLS... BUT WOULDN/T EXPECT THE MODE TO REMAIN DISCRETE FOR VERY LONG GIVEN THE EXPECTATION FOR SOMEWHAT WIDESPREAD DEVELOPMENT. SO... CURRENT EXPECTATIONS WOULD BE FOR INITIAL SUPERCELLS TO QUICKLY TRANSITION INTO CLUSTERS AND A LINEAR SYSTEM WITH TIME. LOW LEVEL SHEAR DOESN/T LOOK TO BE TOO SIGNIFICANT... LIKELY AOB 15-20KT... WHICH SHOULD KEEP TORNADOES FROM BEING MUCH OF A THREAT... LEAVING LARGE HAIL AND WIND AS THE MAIN POTENTIAL ISSUES. THE FRONT SHOULD PUSH THROUGH THE REMAINDER OF THE FORECAST AREA TUESDAY NIGHT... WITH DRY WEATHER AND COOLER TEMPERATURES ON WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE AREA. THE NEXT CHANCE FOR PCPN LOOKS TO HOLD OFF UNTIL THURSDAY AFTERNOON AND THURSDAY NIGHT... WHEN THE MAIN UPPER LOW OVER CENTRAL CANADA DROPS SOUTH TOWARD THE INTERNATIONAL BORDER AND ANOTHER COLD FRONT PUSHES ACROSS THE REGION. MOISTURE RETURN WILL BE LIMITED AHEAD OF THE FRONT... BUT WILL BE SUFFICIENT GIVEN DECENT FORCING FOR SOME SHRA/TSRA. KEPT THINGS MAINLY DRY FROM FRIDAY THROUGH SUNDAY WITH THE EXPECTATION THAT AN EXPANSIVE HIGH WILL BUILD IN FROM CANADA. HOWEVER... IT SHOULD BE NOTED THAT THE 00Z ECMWF IS MORE PROGRESSIVE THAN THE GFS WITH THE UPPER PATTERN AND MANAGES TO FLATTEN THE FLOW OVER THE NORTH CENTRAL CONUS AND BRINGS A SURFACE LOW ACROSS MINNESOTA ON SUNDAY WITH DECENT FRONTOGENESIS AND AN ACCOMPANYING SLUG OF PCPN. STUCK CLOSER TO THE PREVIOUS FORECAST AND GFS AT THIS POINT... AND JUST INCLUDED SOME CHANCE POPS OVER THE SOUTHWEST PORTION OF THE CWFA ON SUNDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 559 AM CDT MON AUG 5 2013 TURNING OUT TO BE QUITE THE UGLY AVIATION MORNING OUT THERE...AS IFR/MVFR CIGS ARE FILLING IN ACROSS THE AREA IN THE WAKE OF THE RAIN SHIELD NOW MOVING INTO IOWA/WI. IN ADDITION...SOME REMNANT MOISTURE TRANSPORT AND WAA HAS ALLOWED SHOWERS TO REDEVELOP FROM THE TWIN CITIES BACK TO RWF...FURTHER AIDING THE CAUSE OF THE LOW CIGS. FOLLOWED THE IDEA OF THE HOPWRF FOR CIGS...WITH A CLEARING RAPIDLY WORKING FROM WEST TO EAST ACROSS THE AREA BETWEEN 15Z AND 21Z. FOR AFTERNOON CONVECTION...SEE ABOVE FOR WHY IT IS LOOKING LIKE IT WILL BE TOUGH TO GET MUCH GOING TODAY...ESPECIALLY ACROSS MN. COUPLE OF THE HOPWRF MEMBERS STILL SHOWING SOME SCT CONVECTION DEVELOPING IN WRN WI THIS AFTERNOON...SO LEFT A PROB30 TSRA MENTION IN FOR EAU...BUT THAT IS IT. TONIGHT...FOG MAY BECOME A BIG ISSUE AS SKIES CLEAR OUT AND WINDS GO LIGHT AND VRB. WI LOOKS TO HAVE THE GREATEST POTENTIAL FOR DENSE FOG...AS THEY WILL BE THE COOLEST TODAY THANKS TO CLOUDS CLEARING OUT THERE LAST. NMM/ARW BOTH SHOW DENSE FOG DEVELOPING IN WI TONIGHT...SO STARTED TO SHOW SIGNS OF THAT AT THE END OF THE TAFS FOR RNH/EAU. WILL PROBABLY HAVE TO KEEP AN EYE ON THE FG FOR STC AS WELL. KMSP...WILL PROBABLY SEE A HIGH DEGREE OF VARIABILITY IN CIGS FOR THE FIRST COUPLE OF HOURS OF THE TAF...BUT BY 14Z...EXPECT A FAIRLY PERSISTENT DECK OF STRATUS DEVELOP IN THE 015 TO 020 RANGE. TILL THEN WILL LIKELY MAKE SOME PRETTY RAPID AND FREQUENT JUMPS BETWEEN IFR/VFR CIGS. WITH DEWPS BACK IN THE 60S AND HIGHS AROUND 80...CAN NOT COMPLETELY RULE OUT A STRAY SHRA/TSRA THIS AFTERNOON...BUT IT DOES NOT LOOK WORTHY OF MENTIONING IN THE TAF. TONIGHT...MAY HAVE SOME FOG TO DEAL WITH IN THE RIVER VALLEY. /OUTLOOK FOR KMSP/ TUE...TSRA LIKELY AFTERNOON/EVENING. VFR OUTSIDE OF TSRA. WINDS WSW 5-10KTS...BCMG NW OVERNIGHT. WED...VFR. WINDS NW 10 KTS. THU...VFR. CHC TSRA OVERNIGHT. WINDS SW 5 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...MPG
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
709 AM CDT MON AUG 5 2013 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 335 AM CDT MON AUG 5 2013 THE LARGE SCALE FLOW REGIME HAS CHANGED LITTLE OVER THE LAST 24 HOURS WITH A VORTEX OVER HUDSON BAY AND UPPER HIGH CENTERED IN WEST TX AND NW FLOW ALOFT THROUGH THE NATIONS MIDSECTION. WEAK DISTURBANCES ALOFT CONTINUE TO TRACK FROM THE CENTRAL ROCKIES ESEWD THRU KS WITHIN THE FLOW ALOFT. CLUSTERS OF THUNDERSTORMS ACROSS SE KS AND SW MO EARLY THIS MORNING ARE OCCURING TO THE NORTH OF A QUASI- STATIONARY BOUNDARY DRAPPED FROM THE OK PANHANDLE INTO THE LOWER MS VALLEY AND IN ADVANCE OF ONE OF THESE WEAK DISTURBANCES...AND ARE STRONGLY DRIVEN BY A BROAD 30+ KT SWLY LLJ. MODEL CONSENSUS AND RECENT RUNS OF THE HRRR SUGGEST A FAMILIAR THEME TO RECENT MORNINGS...THE ACTIVITY WILL TRACK ESEWD THIS MORNING IN ADVANCE OF THE MIGRATING DISTURBANCE AND AS THE LLJ VEERS TO MORE WESTERLY. THIS SHOULD BRING THE GREATEST IMPACT OF THE WEAKENING SHOWERS AND THUNDERSTORMS TO THE EASTERN OZARKS THIS MORNING...WITH ANY RESIDUAL SHOWERS EXITING BY EARLY AFTERNOON. FORCING FOR ANY PRECIPITATION IS RATHER WEAK AND NON-FOCUSED ELSEWHERE AND WORTHY OF A MERE SLIGHT CHANCE. I THINK THERE WILL BE A SLIGHT NORTHWARD JOG IN THE MCS TRACK TONIGHT INTO TUESDAY AS THE BOUNDARY TO THE SOUTH LIFTS SLIGHTLY AND DISTURBANCES ALOFT TRACK A TAD FURTHER NORTH THAN THE LAST SEVERAL DAYS. PRESENT INDICATIONS ARE THAT THE ONE OR MORE MCSS WILL DEVELOP FROM SOUTH CENTRAL KS INTO SOUTH CENTRAL MO AS THE SWLY LLJ RAMPS UP THIS EVENING AND THEN STRENGTHENS AND VEERS OVERNIGHT. THIS ACTIVITY WILL BE ONGOING WITHIN THIS CORRIDOR AT DAYBREAK TUESDAY AND SHIFTING TO THE ESE DURING THE DAY IN ADVANCE OF THE MIGRATING DISTURBANCE ALOFT AND AS THE LLJ CONTINUES TO VEER. THE HIGHEST POPS WILL BE CONCENTRATED ALONG AN AXIS JEFFERSON CITY TO FARMINGTON. GLASS .LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY) ISSUED AT 335 AM CDT MON AUG 5 2013 CONSENSUS OF THE ECMWF...SREF...AND NAM IS WE SHOULD SEE A SYNOPTIC SCALE COLD FRONT PUSH INTO NRN SECTIONS OF THE AREA LATE TUESDAY NIGHT AND PROGRESS SEWD DURING THE DAY ON WEDNESDAY. A BROAD SWLY LLJ OF 30+ KTS REMAINS FOCUSED AHEAD OF THE FRONT TUESDAY NIGHT AND SHOULD SUPPORT LIKELY PROBABILITIES OF SHOWERS AND THUNDERSTORMS WITH THAT THREAT SHIFTING SEWD AHEAD OF THE FRONT ON WEDNESDAY. THE UPPER FLOW REGIME WILL CHANGE SLIGHTLY WEDNESDAY THROUGH FRIDAY WITH A MORE ZONAL COMPONENT WHILE THE FRONT BECOMES QUASI-STATIONARY FROM THE TN VALLEY ACROSS ARKANSAS INTO NORTHERN OK. THIS MORE ZONAL COMPONENT IN THE FLOW ALOFT WILL BRING THE DISTURBANCE TRACK WEST TO EAST MORE THROUGH THE MID MS VALLEY AND MODULATE THE S/SWLY LLJ...TO BRING A CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS TO THE SOUTHERN 2/3RDS OF THE CWA AT LEAST INTO FRIDAY. GLASS && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 707 AM CDT MON AUG 5 2013 MCS COMPLEX OVER SOUTHWESTERN MO TO CONTINUE TRACKING TO THE EAST SOUTHEAST THIS MORNING...SLIDING JUST SOUTH OF TAF SITES. COULD SEE SOME ISOLATED/SCATTERED ACTIVITY AT KCOU...BUT CONFIDENCE IS LOW...SO JUST KEPT VCSH MENTION THERE. OTHERWISE...MAIN ISSUE TO DEAL WITH IS VARIABLE CLOUD HEIGHTS. IFR/MVFR CIGS HAVE DEVELOPED NORTH OF COMPLEX OVER CENTRAL MO...BUT NOT SURE HOW LONG THEY WILL PERSIST. FOR NOW HAVE MVFR/IFR CIGS SCATTERING OUT AT KCOU/KUIN BY 14Z. REST OF TAF SITES TO SEE LOW END VFR CIGS THROUGH MIDDAY...BEFORE SCATTERING OUT. AS FOR WINDS...TO PERSIST FROM THE SOUTH AND INCREASE TO AROUND 10KTS...THEN DIMINISH TOWARDS SUNSET. ANOTHER ROUND OF STORMS IS POSSIBLE TONIGHT THAT WOULD AFFECT CENTRAL MO...SO ADDED VCSH MENTION TO KCOU AFTER 10Z TUESDAY. SPECIFICS FOR KSTL...MCS COMPLEX OVER SOUTHWESTERN MO TO CONTINUE TRACKING TO THE EAST SOUTHEAST THIS MORNING...SLIDING JUST SOUTH OF TAF SITES. OTHERWISE...MAIN ISSUE TO DEAL WITH IS VARIABLE CLOUD HEIGHTS. LOW END VFR CIGS EXPECTED TO MOVE IN AND PERSIST THROUGH MIDDAY...BEFORE SCATTERING OUT. AS FOR WINDS...TO PERSIST FROM THE SOUTH AND INCREASE TO AROUND 10KTS...THEN DIMINISH TOWARDS SUNSET. ANOTHER ROUND OF STORMS IS POSSIBLE TONIGHT THAT WOULD NOT MOVE INTO METRO AREA TIL AFTER 14Z TUESDAY...SO ADDED VCSH MENTION TO KSTL DURING THIS PERIOD. BYRD && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
635 AM CDT MON AUG 5 2013 .AVIATION...12Z TAFS FOR KOFK...KLNK AND KOMA. LOW CLOUDS WILL LINGER ACROSS EASTERN NEBRASKA THROUGH MUCH OF THE MORNING BEFORE SCATTERING/LIFTING TO VFR. EXPECT IFR CIGS AND MVFR VSBYS AT ALL TAF SITES...BUT IFR VSBYS AT KOFK WILL BE POSSIBLE AT LEAST THROUGH 15Z. VFR CONDITIONS SHOULD PREVAIL BETWEEN 18Z AND 06Z BEFORE MORE LOW CLOUDS AND FOG REDEVELOP TOWARD THE END OF THE TAF PERIOD. THERE IS AN OUTSIDE CHANCE FOR THUNDERSTORMS BETWEEN 18Z AND 00Z...ESPECIALLY IN THE KOFK AREA. THEN MORE STORMS IN WESTERN AND CENTRAL NEBRASKA COULD WORK INTO KOFK/KLNK AREAS AFTER 06Z. BOTH POTENTIAL THUNDERSTORM CHANCES ARE NOT MENTIONED IN TAFS AT THIS TIME DUE TO LOW CONFIDENCE OF OCCURRENCE AND EXPECTED ISOLATED NATURE OF STORMS. DERGAN && .PREV DISCUSSION... /ISSUED 352 AM CDT MON AUG 5 2013/ DISCUSSION... SHORT TERM CONCERNS WILL BE LOW CLOUDS AND FOG THIS MORNING AND POTENTIAL FOR ISOLATED SHOWERS AND THUNDERSTORMS TODAY IN THE NORTH ..THEN ATTENTION TURNS TOTUESDAY CONVECTIVE POTENTIAL. WATER VAPOR SATELLITE IMAGERY AND LIGHTNING DATA SHOW MOISTURE STREAMING NORTHWARD ACROSS MEXICO INTO THE FOUR CORNERS REGION INTO THE PLAINS AND THEN SOUTHEAST TOWARD THE LOWER MISSISSIPPI VALLEY... ANTI-CYCLONICALLY AROUND THE LARGE AREA OF H5 HIGH PRESSURE CENTERED OVER NEW MEXICO AND WEST TEXAS. MEANWHILE...CONVECTION WAS ALSO MOVING INTO THE PACIFIC NORTHWEST AND ACROSS THE NORTHERN PLAINS...WHERE THE STRONGER H3 JET RESIDED. THERE WERE 10 TO 20 METER HEIGHT FALLS ASSOCIATED WITH SHORTWAVE TROFS OVER NORTH DAKOTA AND ALSO NEAR SPRINGFIELD MISSOURI. THERE WAS ABUNDANT MOISTURE OVER THE PLAINS WITH MOST LOCATION ON THE PWAT CHART BETWEEN 100-160% OF NORMAL. WIDESPREAD H85 DEWPOINTS OF +12 TO +16C...WITH A MAX OF +18C AT DDC. H7 DEWPOINTS WERE +9 DEG C AT DDC AND +6 AT TOP. H7 TEMPERATURES HAD WARMED INTO THE +10 TO +14 C RANGE FOR MUCH OF THE PLAINS...WITH THE COOLER TEMPS TOWARD ABR...TOP/SPRINGFIELD. THERE WERE TWO THERMAL RIDGES AT H85...ONE WAS NOSING INTO THE NEBRASKA PANHANDLE AND THE OTHER WAS NOSING INTO THE TEXAS PANHANDLE AND OKLAHOMA. THE LATEST WSR-88D RADAR MOSAIC SHOWED THREE CONVECTIVE COMPLEXES....ONE ACROSS MN/NRN IA...ONE OVER SOUTHEAST KANSAS AND ONE OVER WESTERN SOUTH DAKOTA. AFTER SOME MORNING CLOUDS AND FOG...A STRONG SHORTWAVE TROF OVER NORTH DAKOTA WILL CONTINUE TO PUSH SOUTHEAST TODAY AND WILL DRAG A FRONT INTO NORTHEAST NEBRASKA. THE BULK OF THE CONVECTIVE ACTIVITY SHOULD REMAIN TO OUR NORTH AND EAST...LIMITED BY THE WARM MID LEVEL TEMPERATURES LOCALLY...HOWEVER ISOLATED ELEVATED THUNDERSTORMS COULD MAKE IT INTO NORTHEAST NEBRASKA AND WEST CENTRAL IOWA. THERE IS STRONG DEEP LAYER SHEAR OF 50KTS...SO STORMS WILL NEED TO BE WATCHED NEAR THE SD/NEB BORDER. MOST OF THE SHORT RANGE MODELS LIMIT THE SOUTHWARD PROGRESS DURING THE DAY...HOWEVER THE LATEST RAP IS MORE AGGRESSIVE WITH PRECIPITATION MAKING IT FARTHER SOUTH...SO THIS WILL NEED TO BE WATCHED. WARMER H85 TEMPS ARE EXPECTED AND HAVE HIGHS IN THE 80S ALTHOUGH IF CLOUDS HANG ON...THIS COULD KEEP THE HIGHS A LITTLE LOWER. MONDAY NIGHT...AN MCS IS FORECAST TO DEVELOP OVER THE NORTHERN PLAINS AND SPREAD SOUTHEAST. THIS SYSTEM HAS DECENT INSTABILITY OF 3-4000J/KG AND DEEP LAYER SHEAR OF 45-53KTS THUS STORMS COULD BE SEVERE. THE MODELS HAVE A VARIETY OF SOLUTIONS ON THE PLACEMENT OF THE BEST PRECIP...HOWEVER WILL MAINTAIN HIGH POPS WITH THE FRONT TUESDAY INTO TUESDAY EVENING. POOLING OF MOISTURE ALONG THE FRONT COULD RESULT IN LOCALLY HEAVY RAINS. DRYING ENSUES WITH SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTH SHOULD SHUT DOWN THE PRECIPITATION TUESDAY NIGHT AND WEDNESDAY. HIGHS WEDNESDAY SHOULD BE COOLER...IN THE 70S TO LOWER 80S. RETURN FLOW SETS UP WEDNESDAY NIGHT AND COULD SEE SOME STORMS RETURN ESPECIALLY SOUTHWEST. THE EXTENDED THURSDAY THROUGH SUNDAY. H5 LOW PRESSURE OVER HUDSON BAY WILL SLOWLY MOVE EAST WITH BUILDING HEIGHTS OVER THE ROCKIES AND NORTHWEST FLOW ALOFT FOR THE FORECAST AREA. DEEP MOISTURE WILL REMAIN IN PLACE...ESPECIALLY FOR THE SOUTHERN PART OF THE FORECAST AREA AND THIS IS WHERE THERE WOULD BE A HIGHER RISK OF THUNDERSTORMS. SHORTWAVES IN THE NORTHWEST FLOW ALOFT AND STORMS THAT FORM IN THE WESTERN HIGH PLAINS COULD ROLL EAST FRIDAY NIGHT INTO SUNDAY NIGHT...ALTHOUGH THE EASTERLY LOW LEVEL FLOW OFF THE SURFACE HIGH COULD LIMIT COVERAGE. THERE ARE DECENT MODEL DIFFERENCES BY SUNDAY AS TO WHERE THE FRONTAL SYSTEMS WILL BE THUS HAVE LEFT IN THE CHC POPS. HIGHS WILL CONTINUE TO BE AT OR BELOW NORMAL. ZAPOTOCNY && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1136 AM EDT MON AUG 5 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OVER THE MID ATLANTIC WILL MOVE OFFSHORE TONIGHT. A MOIST SOUTHERLY LOW LEVEL RETURN FLOW WILL PREVAIL THROUGH MID TO LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1130 AM MONDAY... OVERVIEW: SYNOPTIC SUBSIDENCE /HEIGHT RISES/ OVER THE MID-ATLANTIC EARLY THIS MORNING WILL WANE AND SHIFT TO NEW ENGLAND THIS AFT/EVE AS AN UPPER LEVEL TROUGH PROGRESSES FURTHER NORTHEAST INTO THE CANADIAN MARITIMES. ACCORDINGLY...1021 MB SFC HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC THIS MORNING WILL WEAKEN AND SHIFT OFFSHORE THE MID- ATLANTIC COAST THIS AFTERNOON INTO TONIGHT. AS THE SFC HIGH PROGRESSES EASTWARD AND A LIGHT S/SE RETURN FLOW DEVELOPS OVER THE WESTERN CAROLINAS THIS AFT/EVE...A STATIONARY FRONT EXTENDING EASTWARD FROM NORTHERN GA INTO CENTRAL/UPSTATE SC WILL BEGIN TO LIFT NORTH FROM UPSTATE SC INTO WESTERN NC (ALONG AND WEST OF I-77)... WITH MOISTURE SLOWLY INCREASING TONIGHT ALONG AND WEST OF THE HIGHWAY 1 CORRIDOR. SFC DEWPOINTS WILL RANGE FROM THE MID/UPPER 50S (EAST) TO LOWER/MID 60S (WEST/SW) THIS AFTERNOON. PRECIPITATION CHANCES: GIVEN THE AFOREMENTIONED MOISTURE IN ADDITION TO SEASONABLY WEAK MID-LEVEL LAPSE RATES...DIURNAL DESTABILIZATION TODAY WILL BE MARGINAL AND LARGELY CONFINED TO SOUTHWEST PORTIONS OF THE STATE WHERE LOW-LEVEL CONVERGENCE /MOISTURE POOLING/ AND THE SLOW NORTHWARD RETREAT OF THE FRONT WILL CONTRIBUTE TO PERHAPS 250-500 J/KG MLCAPE. GRADUAL LOW-LEVEL MOISTURE RETURN OVERNIGHT WILL RESULT IN A SLOW INCREASE IN MUCAPE...PERHAPS UP TO 500 J/KG IN THE WESTERN PIEDMONT AND 1000 J/KG IN THE FOOTHILLS/MOUNTAINS BY 12Z TUE MORNING. FORCING FOR ASCENT WILL BE CONFINED TO WEAK/SHALLOW LOW-LEVEL CONVERGENCE AND UPSLOPE FLOW IN WESTERN NC THIS AFTERNOON INTO TONIGHT. ALTHOUGH THERE IS AT LEAST A POTENTIAL FOR SMALL AMPLITUDE DISTURBANCES IN W/NW FLOW ALOFT THROUGH TONIGHT...15Z WV IMAGERY AND RAP DATA DO NOT SUGGEST ANY SIGNIFICANT DPVA WILL BE PRESENT. PER 15Z VIS SAT IMAGERY INDICATING SHALLOW AGITATED CU IN THE WEST...A FEW SPRINKLES OR PERHAPS AN ISOLD SHOWER CANNOT BE COMPLETELY RULED OUT IN THE TRIAD OR SW PIEDMONT THIS AFTERNOON... THOUGH PROBS ARE TOO LOW TO WARRANT MENTION IN THE FORECAST. WITH THE ABOVE IN MIND...WILL CONTINUE TO INDICATE DRY CONDITIONS THROUGH MIDNIGHT. INCREASINGLY MOIST LOW-LEVEL UPSLOPE FLOW AND A RELATIVELY BETTER CHANCE FOR SMALL AMPLITUDE DISTURBANCES ALOFT MAY RESULT IN PERIODIC DRIZZLE OR VERY LIGHT RAIN IN THE FAR WESTERN PIEDMONT PRIOR TO SUNRISE TUE...PERHAPS ISOLD TO SCATTERED SHOWER ACTIVITY ALONG AND WEST OF I-77. WILL INDICATE A SLIGHT CHANCE OF SHOWERS IN THE TRIAD AFTER MIDNIGHT. TEMPERATURES: EXPECT HIGHS NEAR OR A FEW DEGREES BELOW NORMAL IN THE LOWER/MID 80S NW PIEDMONT (MORE CLOUD COVER) TO MID/UPPER 80S IN THE SANDHILLS AND SE COASTAL PLAIN (LESS CLOUD COVER). EXPECT LOWS TONIGHT NEAR OR SLIGHTLY BELOW NORMAL...IN THE LOWER TO UPPER 60S...WARMEST IN THE WEST/SW PIEDMONT WHERE MORE CLOUD COVER AND BETTER LOW-LEVEL MOISTURE WILL BE PRESENT AND COOLEST IN THE TYPICAL AREAS OF THE NORTHERN PIEDMONT AND NE COASTAL PLAIN WHERE A DRIER AIRMASS AND LESS CLOUD COVER (AT LEAST INITIALLY) WILL PREVAIL. -VINCENT && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... AS OF 250 AM MONDAY... TUESDAY AND TUESDAY NIGHT... HIGH PRESSURE OFF THE MID-ATLANTIC COAST WILL MAINTAIN WEAK INFLUENCE OVER THE FAR EASTERN PORTIONS OF THE AREA...WHILE MOIST SOUTHERLY FLOW CONTINUES TO TAKE HOLD ACROSS MOST OF CENTRAL NC. HOWEVER...DEWPOINTS ARE FORECAST TO HOLD IN THE MID AND UPPER 60S...LEADING TO LIMITED DESTABILIZATION. ADDITIONAL FORCING IS TOUGH TO PICK OUT IN MODEL GUIDANCE...WITH DISTURBANCES IN THE NORTHWESTERLY UPPER LEVEL FLOW EXPECTED TO MOSTLY PASS TO OUR NORTH AND NO REAL SIGN OF A LEE TROUGH UNTIL LATER IN THE WEEK. WILL KEEP A CHANCE OF SHOWERS AND STORMS IN THE NORTHWEST PIEDMONT LATE TUESDAY AS DIFFERENTIAL HEATING CONVECTION OVER THE MOUNTAINS MAY TRY TO PUSH EAST INTO THE PIEDMONT. HIGHS A COUPLE DEGREES WARMER THAN MONDAY IN THE 84-88 RANGE. TUESDAY NIGHT LOWS IN THE MID TO UPPER 60S. -SMITH FOR WEDNESDAY/WEDNESDAY NIGHT: A WEAK MID LEVEL WAVE EXTENDING FROM LAKE ERIE TO KY/TN EARLY WED WILL SHIFT EASTWARD ACROSS THE APPALACHIANS TO THE NORTHEAST STATES THROUGH WED NIGHT. THIS WAVE WILL SERVE AS A WEAK/DIFFUSE WARM FRONT ALOFT AS THE TX RIDGE BUILDS A BIT TO THE NE AND THE FAST WESTERLIES OVER THE NRN TIER OF THE CONUS FLATTENS OUT. THE SOUTHERN PORTION OF THIS WAVE APPEARS TO CONSIST OF ENERGY EMANATING FROM MCS ACTIVITY OVER MO EARLY TUE... SO EXPECT THIS MCV TO BRING COPIOUS MID LEVEL CLOUDINESS WEDNESDAY... RESULTING IN MOSTLY CLOUDY TO CLOUDY SKIES AREAWIDE. THE INCREASING SOUTHERLY LOW LEVEL FLOW SHOULD BE MOST PRONOUNCED OVER THE MOUNTAINS INTO THE WRN CWA... WHERE LOW LEVEL MASS CONVERGENCE WILL BE ENHANCED ALONG/AHEAD OF THE INCOMING 850 MB FRONT. FORECAST SOUNDINGS SHOW GREATER MOISTURE THROUGH THE COLUMN IN THE WRN CWA WHILE THE AIR BENEATH 600 MB IS DRIER IN THE EAST... AND THE MID LEVEL WARMING CENTERED AROUND 500 MB SHOULD LIMIT INSTABILITY... WITH MODELS GENERALLY SHOWING 1000 J/KG OR LESS IN THE WRN CWA ONLY. BUT THE INCREASING PW VALUES TO AROUND 2 INCHES IN THIS AREA WARRANT GOOD CHANCE POPS IN THE WRN CWA RANGING TO JUST SLIGHT CHANCE IN THE FAR ERN CWA... TAPERING OFF BY LATE EVENING. THICKNESSES ABOUT 10 M BELOW NORMAL WITH PLENTY OF CLOUDS SUPPORT HIGHS AROUND A CATEGORY BELOW NORMAL... 83-87. CONTINUED MOSTLY CLOUDY OVERNIGHT AS THE SKY BEHIND SLOWLY-DEPARTING HIGH-BASED STRATOCU FILLS IN WITH FOG/STRATUS OVERNIGHT. LOWS 68-72. FOR THURSDAY/THURSDAY NIGHT: RELATIVELY DRY. FAST AND FLAT FLOW CONTINUES THU MORNING FROM THE EASTERN ROCKIES AND GREAT PLAINS EASTWARD THROUGH THE OH VALLEY AND GREAT LAKES TO THE MIDATLANTIC AND NORTHEAST. MEANWHILE THE TX RIDGE EXPANDS EASTWARD OVER THE GULF AND SOUTHEAST STATES... A REACTION TO A VORTICITY MAX MOVING FROM THE FOUR CORNERS EAST INTO THE TROUGH BASE OF A STRONG VORTEX CENTERED OVER THE MANITOBA/ONTARIO BORDER. THIS WILL RESULT IN VERY WEAK AND ILL-DEFINED MID LEVEL FLOW OVER NC... NOTED ON NAM/GFS FORECAST SOUNDINGS DEPICTING CONSIDERABLE DRYING ALOFT. AT THE SURFACE... A STRENGTHENING FRONTAL ZONE FROM OK THROUGH THE OH VALLEY TO NEW ENGLAND WILL MOVE LITTLE THROUGH THU NIGHT AS IT WAITS FOR THE CANADA VORTEX TO AMPLIFY SLIGHTLY STARTING FRIDAY... AND THE WEAK LEE TROUGH WILL HOLD OVER THE VA/NC PIEDMONT. THE BETTER LOW LEVEL MOISTURE FLUX WILL BE DEFLECTED TO OUR WEST AND NORTH THROUGH THU NIGHT... IN THE BETTER WARM/MOIST CONVEYOR ZONE... AND PW OVER NC SLIPS TO A RELATIVE MINIMUM. HAVE HELD POPS AT JUST LOW CHANCE MAINLY ACROSS THE FAR WEST AND NRN CWA... ON THE EDGE OF THE RIDGE CORE. WITH FEWER CLOUDS AND AN ASSOCIATED UPTICK OF THICKNESSES TO JUST A BIT BELOW NORMAL... EXPECT HIGHS OF 86-90. SHOULD SEE INCREASING AND THICKENING/LOWERING MID CLOUDS THU NIGHT AS WEAK WESTERLY STEERING FLOW BRINGS BLOWOFF CLOUDS FROM OH VALLEY AND MID MISS VALLEY CONVECTION. LOWS 69-74. -GIH && .LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 220 AM MONDAY... STILL APPEARS THAT WE`LL SEE WET WEATHER FRIDAY/SATURDAY WITH SOME IMPROVEMENT POSSIBLE FOR SUNDAY. THE CANADIAN VORTEX WOBBLES EASTWARD ACROSS ONTARIO TO CENTRAL QUEBEC DURING THIS TIME FRAME... RESULTING IN A SLIGHT SOUTHWARD DIP TO THE WESTERLIES AND EVENTUAL EVOLUTION TO A WNW STEERING FLOW OVER NC BY SUNDAY. THE SURFACE FRONT ACROSS THE OH VALLEY AND NORTHEAST STATES EARLY FRIDAY BECOMES MORE E/W ORIENTED IN RESPONSE TO THIS EASTWARD MOVEMENT OF THE SHALLOW LONGWAVE TROUGH... AND THE LEE TROUGH SHARPENS OVER CENTRAL VA/NC AS BOTH 850 MB WINDS AND PW VALUES INCREASE WITHIN THE ENCROACHING WARM/MOIST CONVEYOR ZONE. EXPECT ABOVE-NORMAL LOWS AND SLIGHTLY BELOW-NORMAL HIGHS FRIDAY/SATURDAY AS WARM THICKNESSES ARE OFFSET BY CLOUDS AND A GOOD CHANCE OF SHOWERS/STORMS. GFS/ECMWF PUSH THE SURFACE FRONT TO SC AND ERN NC BY SUNDAY AS THE AXIS OF THE BROAD LONGWAVE TROUGH SHIFTS OVERHEAD AND JUST TO OUR EAST. WILL RETAIN LOW CHANCE POPS AREAWIDE BUT A LITTLE HIGHER IN THE EAST/SOUTH AS THE FRONT COULD HANG UP IN THE VICINITY. TEMPS NEAR TO SLIGHTLY BELOW NORMAL... ALTHOUGH THIS (ALONG WITH THE SURFACE FRONT POSITION ON SUNDAY) IS FAR FROM CERTAIN. -GIH && .AVIATION /12Z MONDAY THROUGH FRIDAY/... AS OF 710 AM MONDAY... A COLD FRONT HAS PUSHED SOUTH THROUGH THE AREA...WITH DRIER AIR NOW SPREADING ACROSS THE AREA AS HIGH PRESSURE BUILDS IN FROM THE NORTH. THIS WILL LEAD TO A LIGHT/VARIABLE WIND AND VFR CONDITIONS TODAY. THE HIGH PRESSURE WILL SHIFT OFFSHORE TONIGHT...ALLOWING SOUTHERLY RETURN FLOW TO DEVELOP AND MOISTURE TO INCREASE ACROSS THE WESTERN PORTIONS OF THE AREA. HOWEVER...CONDITIONS ARE EXPECTED TO REMAIN VFR..WITH CLOUD DECKS AT OR ABOVE 3500 FT. OUTLOOK... AS MOISTURE INCREASES THIS WEEK...EARLY MORNING STRATUS/FOG POTENTIAL WILL ALSO INCREASE...WITH AFTERNOON SHOWERS AND STORMS POSSIBLE EACH DAY. THE MOST ACTIVE PERIODS FOR SHOWERS/STORMS APPEAR TO WEDNESDAY AFTERNOON AND FRIDAY/SATURDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM..SMITH/HARTFIELD LONG TERM...HARTFIELD AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
945 AM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 944 AM CDT MON AUG 5 2013 LOOKS LIKE IT WILL BE A CLOUDY START TO THE DAY WITH THE MAIN QUESTION BEING HOW FAST AND WHERE CLEARING WILL OCCUR. ALREADY SEEING SOMEWHAT OF A CLEARING LINE JUST NORTH OF THE CANADIAN BORDER WHICH SHOULD SLOWLY DROP INTO OUR NORTH BY LATER THIS MORNING. SHOULD ALSO BE SOME DECREASING CLOUDS ACROSS THE WEST BY LATE MORNING BUT THE EAST MAY BE STUCK UNDER THE CLOUDS THE LONGEST. THIS WILL IMPACT TEMPS BUT NOT MAKE ANY ADJUSTMENTS THERE UNTIL THERE IS A BETTER IDEA TO CLOUD TRENDS. KVWU IS REPORTING A SPRINKLE BUT THAT IS PRETTY ISOLATED. ELBOW LAKE ALSO HAS A LITTLE FOG BUT THINK THAT WILL BE SHORT LIVED. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 SURFACE TROUGH WILL CONTINUE TO PROPAGATE THROUGH THE FA. SCATTERED SHOWERS ACROSS THE EASTERN FA SHOULD BE EAST OF THE REGION BY 12Z. WEAK HIGH PRESSURE WILL MOVE INTO THE REGION. THE MAIN CHALLENGE FOR TODAY WILL BE CLOUDS AND ASSOCIATED TEMPERATURES. THERE IS AN AREA OF LOW CLOUDS BEHIND THE SURFACE TROUGH...ALONG THE INTERNATIONAL BORDER. THIS AREA OF CLOUDS HAS BEEN ADVECTING SOUTHWARD OVER THE PAST FEW HOURS...AND THE LATEST RAP GUIDANCE INDICATES THAT THIS TREND WILL CONTINUE. FOLLOWING THIS GUIDANCE MOST AREAS (EXCEPT PORTIONS OF SOUTHEAST NORTH DAKOTA) WILL LIKELY BE MOSTLY CLOUDY INTO AT LEAST THE EARLY AFTERNOON HOURS. THE THOUGHT IS THAT THE CLOUDS SHOULD BEGIN TO DISSIPATE ENOUGH BY MID-LATE AFTERNOON FOR MAX TEMPS TO BE ABLE TO REACH INTO THE MID-UPPER 70S. THE NEXT UPPER LEVEL WAVE AND ASSOCIATED SURFACE TROUGH/COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT INTO TUESDAY. FORCING AND INSTABILITY APPEAR TO BE STRONGER THAN THIS PAST SYSTEM...WHICH COULD LEAD TO MORE WIDESPREAD ACTIVITY. THE BEST SEVERE POTENTIAL WILL BE SOUTH OF THE FA WHERE INSTABILITY IS STRONGEST. HOWEVER...DEEP LAYER SHEAR WILL BE STRONG AND A FEW STRONGER STORMS WOULD SEEM POSSIBLE (ESPECIALLY TUESDAY AFTERNOON ACROSS SE ND INTO WC MN WHERE THE SFC FRONT WILL BE LOCATED DURING PEAK HEATING). .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 TUESDAY NIGHT-WEDNESDAY NIGHT...HIGH PRESSURE WILL AGAIN MOVE INTO THE REGION WHICH SHOULD LEAD TO MOSTLY DRY CONDITIONS. THURSDAY-SUNDAY NIGHT...00 UTC GFS/ECMWF SHOW SAME BASIC SYNOPTIC PATTERN...BUT DIFFER ON THE SPEED AT WHICH THE CLOSED CANADIAN LOW EJECTS INTO QUEBEC. THE ECMWF IS QUICKER THAN THE GFS AND THIS ALLOWS ANOTHER PACIFIC SHORT-WAVE TO MOVE INTO THE NORTHERN PLAINS NEXT WEEKEND. THE SLOWER GFS MAINTAINS DRY NORTHWEST FLOW ACROSS THE FORECAST AREA. GIVEN MODEL DIFFERENCES...WILL KEEP A MAINLY DRY FORECAST FRIDAY AND BEYOND. BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE THURSDAY AS ANOTHER COLD FRONT SWEEPS ACROSS THE REGION. COLD POOL ALOFT ASSOCIATED WITH DEEP CLOSED LOW WILL KEEP TEMPERATURES WELL BELOW MID-AUGUST NORMALS. HIGHS THURSDAY/ FRIDAY WILL STRUGGLE TO BREAK 70 DEGREES IN PLACES. A GRADUAL WARM-UP IS EXPECTED INTO THE WEEKEND...BUT STILL 5 TO 10 DEGREES COOLER THAN NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 658 AM CDT MON AUG 5 2013 IFR/MVFR CIGS WILL CONTINUE TO ADVECT EAST AND AFFECT MUCH OF THE REGION THIS MORNING...AND INTO THE AFTERNOON HOURS. CIGS WILL GRADUALLY LIFT THROUGH THE MORNING HOURS...BUT SHOULD REMAIN MVFR. THE MAIN CHALLENGE WILL BE WHEN/IF THESE CLOUDS CLEAR/DISSIPATE. USED THE LATEST RAP GUIDANCE FOR TIMING...WHICH HAS BEEN DOING A DECENT JOB WITH REALITY. THUNDER CHANCES INCREASE OVERNIGHT...LIKELY AFFECTING KDVL BY 12Z TUE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...GODON SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
658 AM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 658 AM CDT MON AUG 5 2013 WEAK SURFACE LOW LOCATED BETWEEN CROOKSTON AND FOSSTON IS PROPAGATING TO THE EAST...BUT SLOWER THAN ANTICIPATED. THIS FEATURE AND THE ASSOCIATED SURFACE TROUGH SHOULD BE JUST EAST OF THE FA BY 18Z. WILL ADD PATCHY DRIZZLE FOR THE NORTHERN VALLEY THIS MORNING. THERE IS SOME VALLEY INDUCED DRIZZLE WITH THE LOW LEVEL MOISTURE COMBINED WITH WEAK LIFT FROM THE NORTH WINDS ALONG THE VALLEY. OTHERWISE...LOWERED MAX TEMPS A COUPLE DEGREES AS CONFIDENCE HAS INCREASED THAT CLOUDS WILL REMAIN INTO THE AFTERNOON HOURS. HOWEVER...STILL THINK THAT CLOUDS WILL SCATTER BY MID-AFTERNOON TO ALLOW FOR HEATING INTO THE 70S (EXCEPT FOR MAYBE THE FAR EASTERN FA). && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 SURFACE TROUGH WILL CONTINUE TO PROPAGATE THROUGH THE FA. SCATTERED SHOWERS ACROSS THE EASTERN FA SHOULD BE EAST OF THE REGION BY 12Z. WEAK HIGH PRESSURE WILL MOVE INTO THE REGION. THE MAIN CHALLENGE FOR TODAY WILL BE CLOUDS AND ASSOCIATED TEMPERATURES. THERE IS AN AREA OF LOW CLOUDS BEHIND THE SURFACE TROUGH...ALONG THE INTERNATIONAL BORDER. THIS AREA OF CLOUDS HAS BEEN ADVECTING SOUTHWARD OVER THE PAST FEW HOURS...AND THE LATEST RAP GUIDANCE INDICATES THAT THIS TREND WILL CONTINUE. FOLLOWING THIS GUIDANCE MOST AREAS (EXCEPT PORTIONS OF SOUTHEAST NORTH DAKOTA) WILL LIKELY BE MOSTLY CLOUDY INTO AT LEAST THE EARLY AFTERNOON HOURS. THE THOUGHT IS THAT THE CLOUDS SHOULD BEGIN TO DISSIPATE ENOUGH BY MID-LATE AFTERNOON FOR MAX TEMPS TO BE ABLE TO REACH INTO THE MID-UPPER 70S. THE NEXT UPPER LEVEL WAVE AND ASSOCIATED SURFACE TROUGH/COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT INTO TUESDAY. FORCING AND INSTABILITY APPEAR TO BE STRONGER THAN THIS PAST SYSTEM...WHICH COULD LEAD TO MORE WIDESPREAD ACTIVITY. THE BEST SEVERE POTENTIAL WILL BE SOUTH OF THE FA WHERE INSTABILITY IS STRONGEST. HOWEVER...DEEP LAYER SHEAR WILL BE STRONG AND A FEW STRONGER STORMS WOULD SEEM POSSIBLE (ESPECIALLY TUESDAY AFTERNOON ACROSS SE ND INTO WC MN WHERE THE SFC FRONT WILL BE LOCATED DURING PEAK HEATING). .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 TUESDAY NIGHT-WEDNESDAY NIGHT...HIGH PRESSURE WILL AGAIN MOVE INTO THE REGION WHICH SHOULD LEAD TO MOSTLY DRY CONDITIONS. THURSDAY-SUNDAY NIGHT...00 UTC GFS/ECMWF SHOW SAME BASIC SYNOPTIC PATTERN...BUT DIFFER ON THE SPEED AT WHICH THE CLOSED CANADIAN LOW EJECTS INTO QUEBEC. THE ECMWF IS QUICKER THAN THE GFS AND THIS ALLOWS ANOTHER PACIFIC SHORT-WAVE TO MOVE INTO THE NORTHERN PLAINS NEXT WEEKEND. THE SLOWER GFS MAINTAINS DRY NORTHWEST FLOW ACROSS THE FORECAST AREA. GIVEN MODEL DIFFERENCES...WILL KEEP A MAINLY DRY FORECAST FRIDAY AND BEYOND. BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE THURSDAY AS ANOTHER COLD FRONT SWEEPS ACROSS THE REGION. COLD POOL ALOFT ASSOCIATED WITH DEEP CLOSED LOW WILL KEEP TEMPERATURES WELL BELOW MID-AUGUST NORMALS. HIGHS THURSDAY/ FRIDAY WILL STRUGGLE TO BREAK 70 DEGREES IN PLACES. A GRADUAL WARM-UP IS EXPECTED INTO THE WEEKEND...BUT STILL 5 TO 10 DEGREES COOLER THAN NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 658 AM CDT MON AUG 5 2013 IFR/MVFR CIGS WILL CONTINUE TO ADVECT EAST AND AFFECT MUCH OF THE REGION THIS MORNING...AND INTO THE AFTERNOON HOURS. CIGS WILL GRADUALLY LIFT THROUGH THE MORNING HOURS...BUT SHOULD REMAIN MVFR. THE MAIN CHALLENGE WILL BE WHEN/IF THESE CLOUDS CLEAR/DISSIPATE. USED THE LATEST RAP GUIDANCE FOR TIMING...WHICH HAS BEEN DOING A DECENT JOB WITH REALITY. THUNDER CHANCES INCREASE OVERNIGHT...LIKELY AFFECTING KDVL BY 12Z TUE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...TG SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...TG
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1028 AM CDT MON AUG 5 2013 .UPDATE...FORECAST HAS BEEN MODIFIED SIGNIFICANTLY TO LOWER POPS ESPECIALLY IN EASTERN CWA. TRENDS IN HRRR SUPPORT MORE IN THE WAY OF SCATTERED COVERAGE THIS AFTERNOON. INITIAL PRECIP AREA HAS DIMINISHED AND REMNANTS HAVE SHIFTED SOUTH AND SOUTHEAST OF THE CWA. UPSTREAM BREAKS IN THE CLOUD COVER ALONG WITH THE SWIFT UPPER NW FLOW...JET STREAM DYNAMICS SHOULD RESULT IN AT LEAST SCATTERED REDEVELOPMENT PER THE HRRR. SEEING SOME OF THIS UPSTREAM IN NE IA...WITH OTHER WEAKER DEVELOPMENT NORTH AND NORTHWEST OF LA CROSSE. PC && .AVIATION/18Z TAFS/...MID LEVEL DECK ASSOCIATED WITH BATCH OF SHRA THAT MOVED THROUGH GRADUALLY SHOWING SOME DECREASE ACROSS SC WI. MORE SHRA/ISOLD TSRA DEVELOPMENT EXPECTED THIS AFTERNOON/THIS EVENING WITH MID LEVEL JET STREAK AND INCREASED MOISTURE. WITH WEAKER GRADIENT IN PLACE TONIGHT INTO EARLY TUESDAY WILL HAVE TO WATCH FOR STRATUS/FOG DEVELOPMENT. CURRENT TAFS HAVE THIS HANDLED WELL AND SEE NO REASON TO DEVIATE TOO MUCH FROM THE PRIOR THINKING. PC && .PREV DISCUSSION... /ISSUED 329 AM CDT MON AUG 5 2013/ TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH MID/UPPER LEVEL NORTHWEST FLOW CONTINUES WITH A 112 KNOT 250 MB JET MAX THAT REACHES WISCONSIN DURING THE EARLY MORNING HOURS. THE RIGHT ENTRANCE REGION BRINGS AN AREA OF MODERATE UPPER DIVERGENCE INTO WISCONSIN BY SUNRISE. THE JET MAX REMAINS ACROSS SOUTHERN WISCONSIN THROUGH THE AFTERNOON BEFORE WEAKENING TONIGHT. SEVERAL 500 MB CYCLONIC VORTICITY MAXIMUM MOVE ACROSS SOUTHERN WISCONSIN TODAY AND TONIGHT...SOME LIKELY CONVECTIVELY INDUCED. MODERATE 700 MB UPWARD MOTION PUSHES INTO WEST CENTRAL WISCONSIN BY SUNRISE AND ACROSS SOUTHERN WISCONSIN THIS MORNING. THE 700 MB LAYER SATURATES DURING THE EARLY MORNING AS THE 850/700 MB MOISTURE CONVERGENCE INCREASES IN THE BAROCLINIC ZONE ACROSS SOUTHWEST WISCONSIN BEFORE WARM AIR ADVECTION BEGINS. THE LARGE SURFACE HIGH WILL BE CENTERED OVER OHIO BY SUNRISE WITH WEAK SOUTH WINDS ON THE BACK SIDE OF THE HIGH AHEAD OF A WEAK SURFACE TROUGH OVER MINNESOTA. SHOWERS SHOULD PUSH INTO AREAS WEST OF MADISON AFTER SUNRISE AND SPREAD ACROSS SOUTHEAST WISCONSIN LATER THIS MORNING. LIMITED ELEVATED CAPE...BUT WITH 100 JOULES/KG SEEN ON THE SOUNDINGS IF LIFTED FROM 8 THSD FT...ISOLATED/SCATTERED THUNDERSTORMS ARE EXPECTED. THE MAIN BAND OF SHOWERS WILL EXIT THE SOUTHEAST LATER DURING THE AFTERNOON. HOWEVER MOISTURE REMAINS IN PLACE...AND WITH WEAK 850/700 MB MOISTURE CONVERGENCE CONTINUING TONIGHT...MORE SHOWERS WILL BE POSSIBLE. LOW LEVELS REMAIN MOIST AND THE NAM DEVELOPS ALMOST 500 JOULES/KG OF CAPE LATE TONIGHT ACROSS THE FORECAST AREA. THEREFORE THE CHANCE OF THUNDERSTORMS WILL CONTINUE WITH THE WEAK LOW LEVEL LIFT. TUESDAY AND WEDNESDAY...FORECAST CONFIDENCE...MEDIUM LOOKS PRETTY QUIET DURING THE DAY TUESDAY. THE NAM IS SHOWING CONVECTION THROUGH THE DAY...BUT OTHER MODELS SHOWING MORE OF A CAP TO KEEP THINGS MAINLY DRY. KEPT POPS ON THE LOW END. SHOULD SEE SHOWERS/STORMS IN THE EVENING AND OVERNIGHT AS THE COLD FRONT AND MAIN SHORTWAVE MOVE THROUGH...SO KEPT LIKELY POPS GOING. EXPECTING AT LEAST A LITTLE SUNSHINE TUESDAY...SO STILL THINK LOW TO EVEN MID 80S POSSIBLE WITH 925 MB TEMPS IN THE 21-23C RANGE. SHOULD SEE THE PRECIP EXIT WEDNESDAY MORNING...TURNING DRY IN THE AFTERNOON AS HIGH PRESSURE BEGINS TO BUILD IN BEHIND THE FRONT. SHOULD SEE HIGH TEMPS NEAR TO A COUPLE DEGREES BELOW NORMAL. THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE...MEDIUM GENERALLY LOOKS PLEASANT TO END THE WEEK...AS HIGH PRESSURE SLIDES IN BEHIND THE DEPARTING FRONT THURSDAY WITH TEMPS A BIT BELOW NORMAL. WILL SEE NEAR NORMAL TEMPS FRIDAY WITH A WEAK FRONT AT SOME POINT. A SHOWER OR TWO IS NOT OUT OF THE QUESTION...BUT IT LOOKS LIKE MAINLY A DRY FRONTAL PASSAGE. HIGH PRESSURE WILL THEN LIKELY RETURN SATURDAY...WITH CURRENT MODELS SUGGESTING DRY WEATHER THROUGH THE WEEKEND WITH TEMPS A BIT BELOW NORMAL. AVIATION/12Z TAFS/... EXPECT THE CLOUDS TO THICKEN AND LOWER THIS MORNING AHEAD OF THE APPROACHING JET MAX AND UPWARD MOTION. SHOWERS SHOULD PUSH INTO AREAS WEST OF MADISON AROUND SUNRISE AND ACROSS THE SOUTHEAST DURING THE MORNING. WIDESPREAD MVFR CIGS/VSBYS EXPECTED...AND WITH LOW LEVEL MOISTURE IN PLACE SOME IFR CIGS/VSBYS TONIGHT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ TODAY/TONIGHT AND AVIATION/MARINE...HENTZ TUESDAY THROUGH SUNDAY...DDV
AREA FORECAST DISCUSSION
NWS TUCSON AZ
207 PM MST MON AUG 5 2013 .SYNOPSIS...SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE THROUGH THE EARLY PORTION OF THE WEEK...THEN A BIT DRIER WITH ISOLATED TO SCATTERED THUNDERSTORMS FROM THE MIDDLE OF THE WEEK INTO NEXT WEEKEND. && .DISCUSSION...VISIBLE IMAGERY SHOWS A DOUBLE VORTEX MCV FROM THE DECAYING COMPLEX LAST NIGHT AND EARLY THIS MORNING IS NOW NEAR SHOW LOW. MEANWHILE...ANOTHER MCV IS OVER WEST CENTRAL SONORA...RIGHT ALONG THE COAST. EXTENSIVE MID LEVEL CLOUDINESS ASSOCIATED WITH THIS SYSTEM EXTENDS NORTHWARD ACROSS NORTHWEST SONORA AND INTO SOUTH CENTRAL ARIZONA. MEANWHILE...MOSTLY CLEAR SKIES ARE EVIDENT ACROSS SOUTHEAST ARIZONA...MORE SPECIFICALLY OVER MUCH OF GREENLEE...GRAHAM AND COCHISE COUNTIES. IN ADDITION...CONVECTION HAS BEEN IGNITING OVER THE SIERRA MADRES OF NORTHWEST CHIHUAHUA. THIS BAND OF STORMS SHOULD CONTINUE TO LIFT TO THE NORTH WITH VARIOUS MODELS SUGGESTING THAT ACTIVITY WILL GET STARTED ALONG THE INTERNATIONAL BORDER THIS AFTERNOON. THAT SAID...WATER VAPOR IMAGERY SHOWS AN IMPULSE OVER SOUTHERN SONORA MEXICO AND MOVING NORTHWARD WHICH HAS BEEN PART OF THE IMPETUS FOR THE CURRENT DEVELOPMENT OVER THE SIERRA MADRES. MODELS PICK UP ON THIS FEATURE WITH THE MODELS SHOWING IT MOVING ACROSS NORTHERN SONORA MEXICO AND INTO SOUTHERN ARIZONA OVERNIGHT. IN ADDITION...THE HRRR AND THE U OF A WRF-NAM SUGGEST THAT WE SHOULD SEE LIGHT ACTIVITY THROUGH THE EARLY AFTERNOON...BUT CONVECTION WILL IGNITE EITHER SIDE OF THE INTERNATIONAL BORDER AND SPREAD NORTH DURING THE MID TO LATE AFTERNOON AND CONTINUE INTO THE EVENING HOURS. SHOULD EVEN SEE CONVECTION CONTINUE AFTER MIDNIGHT TONIGHT AS THE VORT MAX MOVES THROUGH THE AREA. ADJUSTED THE POP FORECAST FOR THE 00Z-06Z PERIOD TO INCREASE CHANCES ALONG THE INTERNATIONAL BORDER WEST OF NOGALES AND COVERING SOUTHERN PORTIONS OF THE TOHONO O`ODHAM NATION. AS THE SYSTEM FROM NORTHERN MEXICO MAKES ITS WAY NORTHWARD THROUGH THIS EVENING AND OVERNIGHT...AND EVENTUALLY INTO THE NORTHERN PART OF THE STATE BY LATE TUESDAY...THE FORCING FROM THIS SYSTEM SHOULD RESULT IN SCATTERED STORM DEVELOPMENT OVER MOST OF THE DESERT/VALLEY LOCATIONS AND SLIGHTLY BETTER CHANCES FOR THE HIGHER TERRAIN ON TUESDAY. BY WEDNESDAY THE PACIFIC STORM SYSTEM WILL BEGIN TO MOVE ALONG THE COASTAL AREAS OF NORTHERN CALIFORNIA BY LATE WEDNESDAY OR EARLY THURSDAY. THIS WILL RESULT IN WEST TO SOUTHWEST WINDS ALOFT AHEAD OF THIS SYSTEM PUSHING MOISTURE TO THE EAST. RAIN CHANCES WILL DECREASE FROM THE MIDDLE TO LATTER PART OF THE WEEK. AS THE PACIFIC LOW LIFTS INTO OREGON OVER THE WEEKEND...THE HIGH TO THE EAST WILL RETROGRADE A BIT FOR A WARMING TREND. HIGHS WILL GENERALLY BE AROUND 3 TO 5 DEGS BELOW NORMAL TUESDAY... THEN NEAR NORMAL FOR WEDNESDAY...AND SLIGHTLY ABOVE NORMAL FOR THURSDAY. THEREAFTER...HIGHS ABOUT 3 TO 5 DEGS ABOVE NORMAL. LOWS WILL BE AROUND 1 TO 3 DEGS ABOVE NORMAL FOR TUESDAY THROUGH FRIDAY MORNINGS...THEN ABOUT 4 TO 6 DEGS ABOVE NORMAL FOR SATURDAY THROUGH MONDAY. && .AVIATION...SCT-BKN CLOUDS AT 10-13K FT AGL...AND BKN-OVC CLOUDS AOA 20K FT AGL THRU 05/23Z. AFT 05/23Z...SCT CLOUDS AT 7-10K FT AGL WITH ISOLD SHRA/TSRA THROUGH 05/23Z...THEN SCT TSRA DEVELOPING AFT 05/23Z AND CONTINUING THRU 06/05Z...ESPECIALLY FROM KDUG TO KOLS AND AREAS FARTHER WEST. THESE STORMS WILL THEN MOVE NORTH LATER THIS EVENING WITH A POTENTIAL FOR ISOLD ACTIVITY PERSISTING OVERNIGHT. WIND GUSTS TO 45 KTS NEAR ANY TSRA...AS WELL AS LOCAL MVFR/IFR CIGS/VSBYS. OTHERWISE...SURFACE WIND GENERALLY LESS THAN 10 KTS THRU 06/18Z. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...MOISTURE WILL REMAIN IN PLACE ACROSS THE REGION THROUGH THE FIRST PART OF THIS WEEK...RESULTING IN A CHANCE OF MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ACROSS SOUTHEAST ARIZONA. SLIGHTLY DRIER AIR WILL MOVE IN FROM THE WEST DURING THE LATTER PART OF THE WEEK AND INTO THE WEEKEND FOR SLIGHTLY LESSER RAIN CHANCES. OUTSIDE OF GUSTY THUNDERSTORM OUTFLOWS...WINDS DURING THE PERIOD ARE EXPECTED TO BE LIGHT...GENERALLY LESS THAN 15 MPH AND DIURNALLY DRIVEN. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
352 PM MDT MON AUG 5 2013 .SHORT TERM...CURRENT ANALYSIS SHOWS SCATTERED STORMS OVER THE MOUNTAINS WITH A FEW JUST BEGINNING TO SPREAD EASTWARD ONTO THE HIGHER TERRAIN NEAR THE WYOMING BORDER. STILL SEE THE MAIN THREAT OF ANY SEVERE STORMS NORTHEAST OF A LINE FROM WELLINGTON TO FORT MORGAN AND LIMON WHERE BEST COMBINATION OF DAYTIME HEATING AND DEEPEST MOISTURE/INSTABILITY EXISTS WITH CAPES OF 1000-2000 J/KG. FARTHER WEST INCLUDING THE I-25 URBAN CORRIDOR...TEMPERATURES WERE FINALLY BEGINNING TO WARM POST SURGE...BUT STILL STRUGGLING TO REACH CONVECTIVE TEMPS. AS A RESULT...NOT CERTAIN WE WILL SEE STORMS BUT STILL HAVE A COUPLE HOURS TO WARM AND HELP BREAK THE CAP. IN ANY CASE...DEWPOINTS WERE BEGINING TO MIX SO THREAT OF ANY STRONGER STORMS CLOSER TO THE FOOTHILLS LOOKS LOW BARRING ANY STRONGER OUTFLOWS. SHOWERS AND STORMS ARE EXPECTED TO DECREASE FROM WEST TO EAST THROUGH THE COURSE OF THE EVENING AS UPPER LEVEL DIVERGENCE ASSOCIATED WITH RIGHT REAR ENTRANCE REGION OF UPPER JET CONTINUES TO PUSH EAST. FOR TUESDAY...THE PLAINS FORECAST WILL LIKELY HINGE ON THE POSSIBILITY OF ANOTHER SURGE OF SLIGHTLY COOLER BUT MORE MOIST AIR. THIS WOULD BE FROM YET ANOTHER STORM COMPLEX LIKELY TO ORIGINATE IN THE NORTHERN PLAINS AND ROLL SOUTHEAST THROUGH NEBRASKA OVERNIGHT. AS A RESULT...HAVE COOLED OFF THE NORTHEAST CORNER A BIT...RAISED DEWPOINTS...AND WILL KEEP A LITTLE BETTER CHANCE OF STORMS ON THE PLAINS LATE IN THE AFTERNOON. .LONG TERM...CHANCE OF STORMS TO PERSIST ACROSS THE MOUNTAINS THROUGH THE EVENING WITH SOME INCREASE IN SUBTROPICAL MOISTURE. ACROSS PLAINS...AIRMASS LOOKING MORE MOIST WITH AN INCREASE IN LOW LEVEL MOISTURE BUT A BIT MORE STABLE BEHIND AFTERNOON`S COLD FRONT..NOW LOOKING LIKE THE BEST CHANCE FOR STORMS TO BE ALONG FOOTHILLS AND PALMER DIVIDE. AFTER MIDNIGHT...THERE IS SOME INCREASE IN MID LEVEL QG ASCENT AS UPPER TROUGH MOVES INTO THE GREAT BASIN. THIS SHOULD ALLOW FOR AT LEAST A CHANCE OF STORMS OVER THE MOUNTAINS WITH PERHAPS SOME INCREASE ACROSS THE PLAINS. WITH THE INCREASE IN LOW LEVEL MOISTURE...SOME STORMS COULD PRODUCE BRIEF MODERATE TO HEAVY RAINFALL. ON WEDNESDAY...UPPER TROUGH TO SLOWLY MOVE ACROSS COLORADO WITH AN INCREASE IN MID LEVEL QG ASCENT. CROSS SECTIONS STILL INDICATING DECENT MOISTURE ACROSS AREA. ENOUGH SHEAR AND MID LEVEL ASCENT WILL HELP TO INCREASE STORM CHANCES ACROSS MOUNTAINS IN AND NEAR FOOTHILLS BY THE AFTERNOON AND WILL INCREASE POPS TO THE LIKELY CATEGORY. COOLER AIRMASS TO LIMIT THE INTENSITY OF THE STORMS...STILL THE POTENTIAL FOR LOCALLY HEAVY RAINFALL WITH AN INCREASING THREAT OF FLOODING ALONG THE FOOTHILLS. HIGHS TO COOL INTO THE MIDDLE 70S ACROSS THE PLAINS. STORMS TO DECREASE DURING THE EVENING AS TROUGH AXIS SHIFTS ACROSS THE EASTERN PLAINS...ENDING OVER MUCH OF THE AREA AFTER MIDNIGHT. ON THURSDAY....UPPER TROUGH TO BE EAST OF THE AREA WITH WEAK SUBSIDENCE SPREADING INTO NORTHWEST COLORADO. CROSS SECTIONS STILL SHOW GOOD MOISTURE ACROSS THE AREA...MAINLY ACROSS THE MOUNTAINS. WILL MAINTAIN THE CHANCE OF STORMS FOR THE HIGH COUNTRY AND A SLIGHT CHANCE OVER THE PLAINS. TEMPERATURES TO WARM SLIGHTLY...INTO THE LOWER AND MIDDLE 80S ACROSS THE PLAINS. ON FRIDAY...SOUTHWEST FLOW ALOFT TO PREVAIL WITH UPPER HIGH CENTERED OVER EASTERN TEXAS. FLOW TO BRING AN INCREASE IN SUBTROPICAL MOISTURE ACROSS THE AREA... MAINLY ACROSS THE MOUNTAINS. BEST CHANCE FOR STORMS TO BE OVER THE HIGH COUNTRY DURING THE AFTERNOON AND EVENING. FOR THE LATER DAYS SATURDAY THROUGH SUNDAY: SOUTHWEST FLOW ALOFT TO PREVAIL WITH SUBTROPICAL MOISTURE STILL AFFECTING THE AREA. LATEST MODELS KEEP SURFACE FRONT EAST OF THE AREA SATURDAY...SO CHANCES FOR STORMS ACROSS PLAINS NOT EXPECTED TO INCREASE. WILL MAINTAIN THE CHANCE FOR THUNDERSTORMS ACROSS THE MOUNTAINS DURING THE AFTERNOON AND EVENING...WITH A SLIGHT CHANCE OVER THE PLAINS. TEMPERATURES TO GRADUALLY WARM INTO THE MID AND UPPER 80S ACROSS THE PLAINS. && .AVIATION...THREAT OF AT LEAST SOME HIGH BASED CONVECTION IS HIGH ENOUGH TO WARRANT POSSIBILITY OF GUSTY WINDS TIL AROUND 02Z-03Z. MESOSCALE HRRR MODELS SUPPORTS THIS SCENARIO AS WELL. WILL ADDRESS THUNDER THREAT AS NEEDED...BUT ONLY A CHANCE AT THIS POINT. OTHERWISE WINDS WILL EVENTUALLY TRANSITION TO DRAINAGE WINDS OVERNIGHT...AND THEN BACK TO NORTH/NORTHEASTERLIES BY 16Z-18Z TUESDAY. && .HYDROLOGY...LOOKS LIKE THE FOOTHILL BURN SCARS ARE ON THE EDGE OF DEEPER MOISTURE AND HEAVIER RAIN THREAT. STRONGER STORMS ON THE PLAINS WILL BE CAPABLE OF PRODUCING 1 TO 1.5 INCHES IN 40 MINUTES...WHILE STRONGER FOOTHILL STORMS COULD PRODUCE 0.5 TO 0.75 INCH. SIMILAR SITUATION EXPECTED TUESDAY. ON WEDNESDAY...PRECIPITABLE WATER VALUES INCREASE AND MORE EFFICIENT RAINERS ARE ANTICIPATED. STORM COVERAGE SHOULD ALSO BE CONSIDERABLY HIGHER RESULTING IN A HIGHER THREAT OF FLOODING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BARJENBRUCH LONG TERM....D-L AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION...CORRECTED
NWS PUEBLO CO
323 PM MDT MON AUG 5 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 244 PM MDT MON AUG 5 2013 ACTIVE DAY FOR THE WESTERN SLOPES TODAY AS THUNDERSTORMS FIRED UP EARLIER THAN PAST COUPLE DAYS WITHIN THE MONSOON PLUME. THIS IS OUT AHEAD OF LEADING DISTURBANCE MOVING THROUGH SOUTHERN AZ. MEANWHILE...ANOTHER DISTURBANCE IS EXITING EASTERN CO TO THE EAST. DEW POINTS HAVE BEEN FALLING OFF ACROSS THE SE MTS/I-25 CORRIDOR AS PROGGED BY MODELS WITH 40 DEW POINTS AND EVEN SOME UPPER 30S. EVEN OUT TOWARDS LA JUNTA AND LAMAR...DEW POINTS HAVE BEEN FALLING INTO THE LOWER 50S AS WINDS HAVE SHIFTED OUT OF THE SOUTH AND EVEN SOUTHWEST AS THE SFC LOW HAS BEEN KICKING EASTWARD. FOR THE REMAINDER OF THIS EVENING...SCATTERED THUNDERSTORMS EXPECTED ACROSS THE MOUNTAINS...WITH HRRR SUGGESTING THUNDERSTORMS WILL SPREAD INTO THE ADJACENT PLAINS DURING THE LATE AFTERNOON/EARLY EVENING. NOT AS MUCH CAPE TODAY...SO NOT EXPECTING ANY STRONG STORMS ALONG THE I-25 CORRIDOR. WRF WAS HITTING WALDO BURN SCAR BETWEEN 3-5 PM...WHILE EACH SUCCESSIVE RUN OF THE HRRR HAS BEN DELAYING THIS POTENTIAL UNTIL A NORTHERLY SURGE AIDED BY CONVECTION ACROSS NE CO DROPS INTO THE PIKES PEAK REGION JUST AS WEAK FORCING ENHANCING WRN CO CONVECTION WORKS ITS WAY EASTWARD ACROSS THE SE MTS. THIS PUTS TIME FRAME FOR WALDO TO GET HIT BETWEEN 6PM-8PM WHICH MAY BE A LITTLE DELAYED FROM BEST SFC BASED HEATING TO REALIZE STRONG CONVECTION AND HIGH RAINFALL RATES. BUT THIS WILL HAVE TO BE MONITORED CLOSELY. OTHER AREA OF CONCERN BESIDES WILL BE OUT WEST ACROSS THE PAPOOSE AND WEST FORK BURN SCARS WHERE THEY WILL BE UNDER THE GUN FROM STORMS AND HEAVY RAINFALL/POTENTIAL FLASH FLOODING UNTIL 8 PM. MEANWHILE...FAR SOUTHEAST PLAINS WILL HAVE TO BE WATCHED CLOSELY AS CONVECTION ACROSS NW KS SENDS A BOUNDARY SOUTHWESTWARD INTO SE CO...INCREASING SFC DEW POINTS. COULD SEE SOME THUNDERSTORMS DEVELOP ALONG THE LEADING EDGE OF THIS OUTFLOW ACROSS KIOWA...PROWERS AND BACA COUNTIES WITH POTENTIAL FOR A STRONG STORM OR TWO. MAIN THREAT WINDOW WILL BE DURING THE EVENING...WITH POTENTIAL FOR NEAR SEVERE HAIL AND WIND. BEST SEVERE THREAT THOUGH APPEARS TO BE JUST NORTH AND EAST OF THE AREA. TONIGHT...LOTS OF MID/HIGH CLOUDINESS WILL KEEP TEMPERATURES ON THE WARM SIDE...WITH POPS DIMINISHING FOR MOST AREAS BY MIDNIGHT. CAN`T RULE OUT SOME ISOLATED SHOWERS AND THUNDERSTORMS OUT WEST WITHIN THE MONSOON PLUME. ON TUESDAY...PERHAPS A BIT MORE ACTIVE OUT WEST AS SHORTWAVES EMBEDDED IN MONSOON PLUME WORK THEIR WAY NORTHWARD THROUGH AZ INTO SRN UT/FOUR CORNERS REGION TOWARDS 00Z. CONTEMPLATED GOING WITH A FLASH FLOOD WATCH FOR THE WEST FORK AND PAPOOSE BURN SCARS TOMORROW...BUT SFC DEW POINTS DON`T APPEAR TO MOISTEN ALL THAT MUCH...AND MODEL QPFS OFF THE LARGER SCALE MODELS ARE NOT ALL THAT MUCH HIGHER. STILL THERE IS SOME INCREASE IN PRECIP WATERS OUT THAT WAY...SO WILL HAVE TO MONITOR THIS POTENTIAL. WILL LET LATER SHIFTS GET A LOOK AT THE HIGH RES SHORT RANGE MODELS AS THEY START TO RESOLVE THAT PERIOD. OTHERWISE...FOR THE EASTERN AREAS LOOKS LIKE MORE OF THE SAME. ANOTHER DAY OF LOWER SFC DEW POINTS ACROSS THE PLAINS WHICH KEEPS LCLS ON THE HIGH SIDE. STILL ENOUGH MOISTURE IN THE MONSOON PLUME FOR SOME LOCALLY HEAVY RAIN WITH THE STRONGER STORMS...BUT FOR NOW THIS THREAT LOOKS TOO LOCALIZED TO WARRANT ANY FLASH FLOOD WATCHES FOR THE WALDO OR BLACK FOREST. THIS COULD CHANGE INTO THE EVENING HOURS AS MODELS DROP A FRONT REINFORCED BY THUNDERSTORM OUTFLOWS INTO THE AREA FROM NE CO. -KT .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 244 PM MDT MON AUG 5 2013 ...HEAVY RAIN EXPECTED ON WEDNESDAY... HIGH PRESSURE OVER TEXAS AND AN AREA OF LOW PRESSURE OFF THE NORTHERN CALIFORNIA COAST WILL FORCE SOUTHERLY MONSOON ENERGY ACROSS COLORADO THROUGH THURSDAY. THIS WILL SET THE STAGE FOR WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TUESDAY NIGHT THROUGH THURSDAY AFTERNOON. EXPECT ACTIVE SHOWER AND THUNDERSTORM ACTIVITY TUESDAY EVENING OVER THE MOUNTAINS AND SPREADING INTO THE PLAINS. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE DURING THIS TIME PERIOD. MODELS INDICATING A SMALL LULL AROUND MIDNIGHT BEFORE ACTIVITY INCREASES AGAIN HEADING INTO WEDNESDAY MORNING. HOW QUICKLY THINGS PICK LATE TUESDAY NIGHT/WEDNESDAY MORNING WILL DEPEND ON HOW FAST A FRONT MOVES SOUTH ACROSS THE AREA...AND A STRONG SHORTWAVE EJECTS NORTHEAST OUT OF THE DESERT SOUTHWEST. FRONTAL TIMING LOOKS TO IMPACT THE AREA BY WEDNESDAY MORNING WITH A VERY MOIST AIR MASS MOVING INTO THE PLAINS BEHIND THE FRONT. IN ADDITION...LOW LEVEL FLOW IS FORECAST TO TURN EASTERLY WITH GOOD UPSLOPE FLOW ACROSS THE PLAINS. ALL OF THESE LOW LEVEL FEATURES WILL COMBINE WITH A VERY STRONG SHORTWAVE TROUGH ACROSS COLORADO TO PRODUCE WIDESPREAD MODERATE TO HEAVY RAINFALL ACROSS THE AREA. IN ADDITION...COLDER AIR ALOFT WILL MOVE INTO THE AREA WHICH WILL LIKELY INCREASE LAPSE RATES AND INSTABILITY ACROSS COLORADO. THE AREA OF GREATEST CONCERN WILL BE THE EASTERN MOUNTAINS AND I-25 CORRIDOR. MODELS ARE INDICATING WELL OVER AN INCH OF PRECIPITATION WILL BE POSSIBLE...ESPECIALLY IF WE CAN GET ENHANCEMENT FROM CONVECTIVE UPDRAFTS. THE ONE CAVEAT MAY BE CLOUD COVER ACROSS THE PLAINS WHICH WOULD LIMIT INSTABILITY AND CONVECTIVE ENHANCEMENT. THIS WILL NEED TO BE WATCHED. FLASH FLOODING WILL BE OF GREAT CONCERN...ESPECIALLY FOR AREA BURN SCARS. EXTREME CAUTION IS ADVISED AND FOLKS SHOULD REMAIN COGNIZANT OF THE WEATHER AROUND THEM. THE UPPER SYSTEM WILL BE SLOW TO MOVE OUT...WITH THE MODERATE TO HEAVY RAINFALL SLOWLY MOVING EAST ACROSS THE PLAINS WEDNESDAY NIGHT. THURSDAY...MOISTURE WILL BE IN PLACE AND DEPARTING UPPER LEVEL ENERGY WILL LIKELY LEAD TO SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE MOUNTAINS THURSDAY AFTERNOON. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE...AND FLASH FLOODING WILL BE POSSIBLE OVER AREA BURN SCARS. IF TRENDS HAVE ANYTHING TO SAY ABOUT IT...THE DAY AFTER EXPECTED WIDESPREAD HEAVY RAINFALL EVENTS SEEM TO BE PRIMED FOR HEAVIER RAINFALL OUT OF THUNDERSTORMS THAN MODELS SEEM TO INDICATE. THE PATTERN BEGINS TO SHIFT FRIDAY INTO EARLY NEXT WEEK. THE LOW OFF NORTHERN CALIFORNIA WILL DRIFT NORTHWARD HAS HIGH PRESSURE OVER TEXAS BUILDS NORTH ACROSS COLORADO. THE MAIN MONSOONAL TAP SHIFTS WESTWARD INTO THE GREAT BASIN. MODELS ARE INDICATING A DOWNWARD TREND IN CONVECTIVE ACTIVITY THROUGH THE WEEKEND WITH SHOWER AND THUNDERSTORM ACTIVITY REMAINING CONFINED TO MOUNTAIN AREAS. MOZLEY && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED AT 244 PM MDT MON AUG 5 2013 THUNDERSTORMS WILL DRIFT EASTWARD INTO THE ADJACENT PLAINS THIS EVENING AND WILL BE MOST LIKELY TO AFFECT KALS AND KCOS. WILL CARRY VCTS IN BOTH THESE TERMINALS THROUGH 01Z...WITH POTENTIAL FOR GUSTY OUTFLOW WINDS 25-30 KTS. KPUB WILL HAVE THE LOWEST CHANCE. THUNDERSTORMS WILL BRING BRIEF MVFR CIGS/VIS. THUNDERSTORMS WILL DIMINISH AFTER SUNSET FOR THE TERMINALS WITH SOME MID/HIGH DECK OF CLOUDINESS PERSISTING OVERNIGHT WHICH SHOULD PREVENT FORMATION OF ANY FOG/LOW STRATUS AT TERMINALS OVERNIGHT. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KT LONG TERM...MOZLEY AVIATION...KT
AREA FORECAST DISCUSSION
NWS PUEBLO CO
305 PM MDT MON AUG 5 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 244 PM MDT MON AUG 5 2013 ACTIVE DAY FOR THE WESTERN SLOPES TODAY AS THUNDERSTORMS FIRED UP EARLIER THAN PAST COUPLE DAYS WITHIN THE MONSOON PLUME. THIS IS OUT AHEAD OF LEADING DISTURBANCE MOVING THROUGH SOUTHERN AZ. MEANWHILE...ANOTHER DISTURBANCE IS EXITING EASTERN CO TO THE EAST. DEW POINTS HAVE BEEN FALLING OFF ACROSS THE SE MTS/I-25 CORRIDOR AS PROGGED BY MODELS WITH 40 DEW POINTS AND EVEN SOME UPPER 30S. EVEN OUT TOWARDS LA JUNTA AND LAMAR...DEW POINTS HAVE BEEN FALLING INTO THE LOWER 50S AS WINDS HAVE SHIFTED OUT OF THE SOUTH AND EVEN SOUTHWEST AS THE SFC LOW HAS BEEN KICKING EASTWARD. FOR THE REMAINDER OF THIS EVENING...SCATTERED THUNDERSTORMS EXPECTED ACROSS THE MOUNTAINS...WITH HRRR SUGGESTING THUNDERSTORMS WILL SPREAD INTO THE ADJACENT PLAINS DURING THE LATE AFTERNOON/EARLY EVENING. NOT AS MUCH CAPE TODAY...SO NOT EXPECTING ANY STRONG STORMS ALONG THE I-25 CORRIDOR. WRF WAS HITTING WALDO BURN SCAR BETWEEN 3-5 PM...WHILE EACH SUCCESSIVE RUN OF THE HRRR HAS BEN DELAYING THIS POTENTIAL UNTIL A NORTHERLY SURGE AIDED BY CONVECTION ACROSS NE CO DROPS INTO THE PIKES PEAK REGION JUST AS WEAK FORCING ENHANCING WRN CO CONVECTION WORKS ITS WAY EASTWARD ACROSS THE SE MTS. THIS PUTS TIME FRAME FOR WALDO TO GET HIT BETWEEN 6PM-8PM WHICH MAY BE A LITTLE DELAYED FROM BEST SFC BASED HEATING TO REALIZE STRONG CONVECTION AND HIGH RAINFALL RATES. BUT THIS WILL HAVE TO BE MONITORED CLOSELY. OTHER AREA OF CONCERN BESIDES WILL BE OUT WEST ACROSS THE PAPOOSE AND WEST FORK BURN SCARS WHERE THEY WILL BE UNDER THE GUN FROM STORMS AND HEAVY RAINFALL/POTENTIAL FLASH FLOODING UNTIL 8 PM. MEANWHILE...FAR SOUTHEAST PLAINS WILL HAVE TO BE WATCHED CLOSELY AS CONVECTION ACROSS NW KS SENDS A BOUNDARY SOUTHWESTWARD INTO SE CO...INCREASING SFC DEW POINTS. COULD SEE SOME THUNDERSTORMS DEVELOP ALONG THE LEADING EDGE OF THIS OUTFLOW ACROSS KIOWA...PROWERS AND BACA COUNTIES WITH POTENTIAL FOR A STRONG STORM OR TWO. MAIN THREAT WINDOW WILL BE DURING THE EVENING...WITH POTENTIAL FOR NEAR SEVERE HAIL AND WIND. BEST SEVERE THREAT THOUGH APPEARS TO BE JUST NORTH AND EAST OF THE AREA. TONIGHT...LOTS OF MID/HIGH CLOUDINESS WILL KEEP TEMPERATURES ON THE WARM SIDE...WITH POPS DIMINISHING FOR MOST AREAS BY MIDNIGHT. CAN`T RULE OUT SOME ISOLATED SHOWERS AND THUNDERSTORMS OUT WEST WITHIN THE MONSOON PLUME. ON TUESDAY...PERHAPS A BIT MORE ACTIVE OUT WEST AS SHORTWAVES EMBEDDED IN MONSOON PLUME WORK THEIR WAY NORTHWARD THROUGH AZ INTO SRN UT/FOUR CORNERS REGION TOWARDS 00Z. CONTEMPLATED GOING WITH A FLASH FLOOD WATCH FOR THE WEST FORK AND PAPOOSE BURN SCARS TOMORROW...BUT SFC DEW POINTS DON`T APPEAR TO MOISTEN ALL THAT MUCH...AND MODEL QPFS OFF THE LARGER SCALE MODELS ARE NOT ALL THAT MUCH HIGHER. STILL THERE IS SOME INCREASE IN PRECIP WATERS OUT THAT WAY...SO WILL HAVE TO MONITOR THIS POTENTIAL. WILL LET LATER SHIFTS GET A LOOK AT THE HIGH RES SHORT RANGE MODELS AS THEY START TO RESOLVE THAT PERIOD. OTHERWISE...FOR THE EASTERN AREAS LOOKS LIKE MORE OF THE SAME. ANOTHER DAY OF LOWER SFC DEW POINTS ACROSS THE PLAINS WHICH KEEPS LCLS ON THE HIGH SIDE. STILL ENOUGH MOISTURE IN THE MONSOON PLUME FOR SOME LOCALLY HEAVY RAIN WITH THE STRONGER STORMS...BUT FOR NOW THIS THREAT LOOKS TOO LOCALIZED TO WARRANT ANY FLASH FLOOD WATCHES FOR THE WALDO OR BLACK FOREST. THIS COULD CHANGE INTO THE EVENING HOURS AS MODELS DROP A FRONT REINFORCED BY THUNDERSTORM OUTFLOWS INTO THE AREA FROM NE CO. -KT .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 244 PM MDT MON AUG 5 2013 ...HEAVY RAIN EXPECTED ON WEDNESDAY... HIGH PRESSURE OVER TEXAS AND AN AREA OF LOW PRESSURE OFF THE NORTHERN CALIFORNIA COAST WILL FORCE SOUTHERLY MONSOON ENERGY ACROSS COLORADO THROUGH THURSDAY. THIS WILL SET THE STAGE FOR WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TUESDAY NIGHT THROUGH THURSDAY AFTERNOON. EXPECT ACTIVE SHOWER AND THUNDERSTORM ACTIVITY TUESDAY EVENING OVER THE MOUNTAINS AND SPREADING INTO THE PLAINS. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE DURING THIS TIME PERIOD. MODELS INDICATING A SMALL LULL AROUND MIDNIGHT BEFORE ACTIVITY INCREASES AGAIN HEADING INTO WEDNESDAY MORNING. HOW QUICKLY THINGS PICK LATE TUESDAY NIGHT/WEDNESDAY MORNING WILL DEPEND ON HOW FAST A FRONT MOVES SOUTH ACROSS THE AREA...AND A STRONG SHORTWAVE EJECTS NORTHEAST OUT OF THE DESERT SOUTHWEST. FRONTAL TIMING LOOKS TO IMPACT THE AREA BY WEDNESDAY MORNING WITH A VERY MOIST AIR MASS MOVING INTO THE PLAINS BEHIND THE FRONT. IN ADDITION...LOW LEVEL FLOW IS FORECAST TO TURN EASTERLY WITH GOOD UPSLOPE FLOW ACROSS THE PLAINS. ALL OF THESE LOW LEVEL FEATURES WILL COMBINE WITH A VERY STRONG SHORTWAVE TROUGH ACROSS COLORADO TO PRODUCE WIDESPREAD MODERATE TO HEAVY RAINFALL ACROSS THE AREA. IN ADDITION...COLDER AIR ALOFT WILL MOVE INTO THE AREA WHICH WILL LIKELY INCREASE LAPSE RATES AND INSTABILITY ACROSS COLORADO. THE AREA OF GREATEST CONCERN WILL BE THE EASTERN MOUNTAINS AND I-25 CORRIDOR. MODELS ARE INDICATING WELL OVER AN INCH OF PRECIPITATION WILL BE POSSIBLE...ESPECIALLY IF WE CAN GET ENHANCEMENT FROM CONVECTIVE UPDRAFTS. THE ONE CAVEAT MAY BE CLOUD COVER ACROSS THE PLAINS WHICH WOULD LIMIT INSTABILITY AND CONVECTIVE ENHANCEMENT. THIS WILL NEED TO BE WATCHED. FLASH FLOODING WILL BE OF GREAT CONCERN...ESPECIALLY FOR AREA BURN SCARS. EXTREME CAUTION IS ADVISED AND FOLKS SHOULD REMAIN COGNOSCENTE OF THE WEATHER AROUND THEM. THE UPPER SYSTEM WILL BE SLOW TO MOVE OUT...WITH THE MODERATE TO HEAVY RAINFALL SLOWLY MOVING EAST ACROSS THE PLAINS WEDNESDAY NIGHT. THURSDAY...MOISTURE WILL BE IN PLACE AND DEPARTING UPPER LEVEL ENERGY WILL LIKELY LEAD TO SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE MOUNTAINS THURSDAY AFTERNOON. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE...AND FLASH FLOODING WILL BE POSSIBLE OVER AREA BURN SCARS. IF TRENDS HAVE ANYTHING TO SAY ABOUT IT...THE DAY AFTER EXPECTED WIDESPREAD HEAVY RAINFALL EVENTS SEEM TO BE PRIMED FOR HEAVIER RAINFALL OUT OF THUNDERSTORMS THAN MODELS SEEM TO INDICATE. THE PATTERN BEGINS TO SHIFT FRIDAY INTO EARLY NEXT WEEK. THE LOW OFF NORTHERN CALIFORNIA WILL DRIFT NORTHWARD HAS HIGH PRESSURE OVER TEXAS BUILDS NORTH ACROSS COLORADO. THE MAIN MONSOONAL TAP SHIFTS WESTWARD INTO THE GREAT BASIN. MODELS ARE INDICATING A DOWNWARD TREND IN CONVECTIVE ACTIVITY THROUGH THE WEEKEND WITH SHOWER AND THUNDERSTORM ACTIVITY REMAINING CONFINED TO MOUNTAIN AREAS. MOZLEY && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED AT 244 PM MDT MON AUG 5 2013 THUNDERSTORMS WILL DRIFT EASTWARD INTO THE ADJACENT PLAINS THIS EVENING AND WILL BE MOST LIKELY TO AFFECT KALS AND KCOS. WILL CARRY VCTS IN BOTH THESE TERMINALS THROUGH 01Z...WITH POTENTIAL FOR GUSTY OUTFLOW WINDS 25-30 KTS. KPUB WILL HAVE THE LOWEST CHANCE. THUNDERSTORMS WILL BRING BRIEF MVFR CIGS/VIS. THUNDERSTORMS WILL DIMINISH AFTER SUNSET FOR THE TERMINALS WITH SOME MID/HIGH DECK OF CLOUDINESS PERSISTING OVERNIGHT WHICH SHOULD PREVENT FORMATION OF ANY FOG/LOW STRATUS AT TERMINALS OVERNIGHT. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KT LONG TERM...MOZLEY AVIATION...KT
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1102 AM MDT MON AUG 5 2013 .UPDATE... ISSUED AT 703 AM MDT MON AUG 5 2013 UPDATED GRIDS/ZONES FOR SLIGHTLY LESS SKY COVERAGE OVER PORTIONS OF THE PLAINS...AND TO DROP LOW POPS FOR THE MTS FOR THE EARLY MON MORNING PERIOD. HIGH CLOUDS CONTINUE TO STREAM UP FROM THE SOUTH...SO STILL THINK WE WILL SEE MORE CLOUDS THAN SUN TODAY. MOST RECENT HRRR IS SHOWING FAIRLY STRONG QPF MOVING OVER THE WALDO AND BLACK FOREST AREAS AFTER 23Z TODAY...WHILE OTHER MODELS ARE A BIT MORE SPARSE. WILL HAVE TO WATCH CONVECTIVE TRENDS CLOSELY THIS AFTERNOON GIVEN THE RECENT HEAVY RAINS. ROSE && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 355 AM MDT MON AUG 5 2013 ...A BIT QUIETER TODAY...STILL SOME FLOODING CONCERNS... CURRENTLY...JUST A FEW SHOWERS LINGERING NR THE KS AND OK BORDERS. KALS FINALLY DRYING OUT AFTER A COUPLE HOURS OF SOME FAIRLY GOOD RAINFALL...NEARLY HALF AN INCH...MOST OF WHICH WAS INVISIBLE TO RADAR DUE TO BLOCKAGE AND DISTANCE FROM THE WSR NETWORK. WILL PROBABLY SEE SOME LOW CLOUDS IN THE VALLEY THIS MORN. OTHERWISE...JUST SOME LOW CLOUDS AND A BIT OF FG POSSIBLE OVER THE FAR SERN PLAINS...ESPECIALLY KIOWA COUNTY. MAIN CONCERN TODAY WILL BE AN UPPER LEVEL DISTURBANCE THAT IS EMBEDDED UNDER THE RIDGE...WHICH CAN BE SEEN CURRENTLY KICKING OFF CONVECTION OVR NM. THIS WILL PROPAGATE THRU WRN CO THIS MORN. MAIN LIFT AND FOCUS FOR CONVECTION WILL BE LATER TODAY OVER KS...SO BELIEVE THAT THE BIGGEST IMPACT FROM THE DISTURBANCE WILL BE MOSTLY E OF OUR CWA. HOWEVER...WILL STILL SEE SCT STORMS DEVELOP EARLY TODAY OVER THE MTS...SPREADING TO THE I-25 CORRIDOR LATE IN THE AFTERNOON. SO...WILL STILL HAVE TO KEEP A CLOSE EYE OUT ON THE BURN SCARS EVEN THOUGH THE INTENSITY AND COVERAGE OF STORMS LOOKS A BIT LESS. FOR THE FAR ERN PLAINS...NR THE KS BORDER...THERE COULD BE MORE VIGOROUS CONVECTION...INCLUDING THE POTENTIAL FOR A STRONG STORM OR TWO...BUT BELIEVE THAT MOST OF THE HEAVY RAIN IMPACT WILL STAY FAR ENOUGH E TO PRESENT A SMALLER RISK FOR THE RIVERS. HAVE ALREADY ISSUED A COUPLE FLOOD WARNINGS FOR THE ARKANSAS AND PURGATOIRE...BUT THESE SPOTS SHOULD CREST AND BEGIN TO RECEDE LATER THIS MORNING. EXTENSIVE MID AND HIGH CLOUDS WILL CONTINUE TO LIMIT TEMPS TODAY...BUT WITH THE RIDGE BUILDING A BIT IT SHOULD BE A COUPLE DEGREES WARMER FOR MOST SPOTS THIS AFTERNOON. HIGH CLOUDS WILL THICKEN UP A BIT OVERNIGHT ESPECIALLY FOR THE NRN AND WRN PORTIONS OF THE CWA...LEADING TO ANOTHER MILD NIGHT. ROSE .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 355 AM MDT MON AUG 5 2013 ...WEDNESDAY COULD BE A RATHER WET AND STORMY DAY... NOT MUCH OVERALL CHANGE IN THE GUIDANCE. AS HAS BEEN STATED OVER THE LAST SEVERAL DAYS...THE MONSOON PLUME WILL REMAIN IN PLACE OVER THE FCST AREA THROUGH THIS FCST PERIOD...AND THIS PATTER N WILL KEEP THE REGION RATHER WET WITH SEASONABLE TEMPERATURES. THE MAIN DAY OF CONCERN APPEARS TO BE WEDNESDAY. NEARLY ALL SIMULATIONS ARE SHOWING THIS DAY IS LIKELY GOING TO BE WET...AND WE WILL LIKELY SEE OUR BEST CHANCE OF HEAVY RAINS OVER THE REGION. QUITE A FEW AREAS HAVE HAD DECENT RAINFALL IN THE LAST WEEK OR SO...SO FLASH FLOODING CONCERNS ARE GOING TO BE MORE WIDESPREAD WITH THIS EVENT (JUST NOT THE BURN SCARS). SIMULATIONS CONTINUE TO INDICATE SEVERAL FEATURES WILL COME INTO PLAY TO BRING THE THREAT OF HEAVY RAIN WEDNESDAY. FIRST...A COOL FRONT WILL MOVE IN TUESDAY NIGHT...BRINGING ANOTHER SURGE OF LLVL MOISTURE INTO THE REGION. THE UPPER LEVEL MONSOON PLUME WILL CONTINUE OVER THE REGION ADDING TO THE MOISTURE ALOFT. ADDITIONALLY...A WELL DEFINED DISTURBANCE WILL MOVE ACROSS THE REGION DURING THE DAY WEDNESDAY...AND THIS FEATURE WILL CREATE FAVORABLE DIFFLUENCE ALOFT TO ACCENTUATE THE UPWARD VERTICAL VELOCITY FIELDS OVER THE REGION. ALL THESE FEATURES COMING TOGETHER SHOULD ALLOW FOR HEAVY CONVECTIVE PRECIP WED. THE ONLY CONCERN I SEE FOR WED IS THAT CAPE MAY BE LIMITED AS IT MAY BE QUITE CLOUDY AND COOL...AND WITH LIMITED INSOLATION...CAPE VALUES MAY NOT GET TOO HIGH. IF WE DO SEE SOME SUN THEN THE THREAT OF HEAVIER RAIN WILL INCREASE. THERE IS ALSO A CHANCE THE CONVECTION MAY BE SEVERE ON THIS DAY (ESPECIALLY IF WE CAN GET SOME DECENT CAPE) AS SHEAR WILL BE MARGINAL FOR ROTATING STORMS. WITH THE LIKELY LOW LCLS...A FEW WEAK SUPERCELL TORNADOES WILL BE POSSIBLE. WRT TO THE NDFD GRIDS...I HAVE LIKELY POPS OVER THE MTNS WED WITH HIGH SCTD POPS ON THE PLAINS. I MENTIONED HEAVY RAIN (R+) IN THE WEATHER GRIDS. IT IS TOO EARLY TO MENTION SVR IN THE NDFD. IN THE MEANTIME...TUESDAY WE WILL SEE SCATTERED STORMS OVER THE MTNS WITH SCTD ACTIVITY MOVING ONTO THE PLAINS LATE IN THE DAY. TUESDAY NIGHT THE COOL FRONT WILL MOVE DOWN...AND I CANNOT RULE OUT SOME LOCALLY HEAVY RAIN THIS EVENING/NIGHT AS AN MCS MAY FORM ON THE SE PLAINS. WEDNESDAY WILL BE BUSY AS ALLUDED TO ABOVE. THURSDAY INTO THE WEEKEND CONTINUES TO LOOK BUSY. UPSLOPE WILL CONTINUE IN THE LLVLS AND MSTR WILL CONTINUE ALOFT WITH THE PERSISTENT SW MONSOON FLOW. NO WELL DEFINED SHORT WAVES ARE EXPECTED...BUT THERE WILL BE ENOUGH FORCING/INSTABILITY TO CONTINUE THE THREAT OF AFTERNOON AND EVENING SHOWER AND STORMS OVER THE ENTIRE REGION. SOME OF THE RAIN WILL BE LOCALLY HEAVY. /HODANISH && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1035 AM MDT MON AUG 5 2013 SCATTERED -TSRA WILL DEVELOP OVER THE MOUNTAINS DURING THE EARLY AFTERNOON AND SPREAD INTO THE VALLEYS/ADJACENT PLAINS AFTER 21Z. KALS AND KCOS CARRY THE BEST PROBABILITIES FOR TSRA...AND WILL MAINTAIN VCTS FOR BOTH...THOUGH WILL BE ADDING A TEMPO GROUP FOR ERRATIC OUTFLOW WINDS DURING THE 22Z-01Z TIMEFRAME. THUNDERSTORMS WILL BRING BRIEF MVFR CIGS/VIS SHOULD THEY HIT THE TERMINALS. THUNDERSTORMS SHOULD DIMINISH AFTER SUNSET FOR THE TERMINALS WITH SOME MID/HIGH DECK OF CLOUDINESS PERSISTING OVERNIGHT WHICH SHOULD PREVENT FORMATION OF ANY FOG/LOW STRATUS AT TERMINALS OVERNIGHT. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ROSE SHORT TERM...ROSE LONG TERM...HODANISH AVIATION...KT
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
132 PM EDT MON AUG 5 2013 .SYNOPSIS... A WEAK BACKDOOR COLD FRONT WILL BECOME NEARLY STATIONARY ACROSS SOUTHERN GEORGIA TODAY...THEN LINGER INTO MID WEEK BEFORE DISSIPATING AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL LATE IN THE WEEK INTO THE WEEKEND...BEFORE ANOTHER BACKDOOR COLD FRONT AFFECTS THE AREA LATE IN THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE FORECAST IS PRETTY MUCH EVOLVING AS EXPECTED. ONLY MINOR CHANGES WERE MADE WITH THE EARLY AFTERNOON UPDATE. MID-MORNING SURFACE ANALYSIS SHOWS THE BACKDOOR COLD FRONT HAS BECOME STATIONARY SOUTH OF THE ALTAMAHA RIVER WITH A COOL EAST/NORTHEAST FLOW PREVAILING ACROSS THE AREA. SHOWERS ARE BEGINNING TO BREAKOUT ALONG PORTIONS OF NORTH COASTAL GEORGIA AHEAD OF WHAT APPEARS TO BE THE 850MB COLD FRONT. HIGH RESOLUTION MODELS ARE SIMILAR IN DEVELOPING ADDITIONAL SHOWERS/TSTMS OVER THE NEXT FEW HOURS ACROSS MAINLY SOUTHEAST GEORGIA SOUTH OF I-16 COINCIDENT WITH THE STRONGEST 850MB CONVERGENCE AXIS. WILL INCREASE POPS TO 30 PERCENT IN THIS AREA THROUGH EARLY AFTERNOON WITH POPS DIMINISHING TO SLIGHT CHANCE LATER THIS AFTERNOON AS THE LATEST RAP SHOWS 850MB CONVERGENCE DIMINISHING WITH TIME. THE WEATHER LOOKS DRY FOR MUCH OF SOUTHEAST SOUTH CAROLINA TODAY. HIGHS WILL RANGE FROM THE MID 80S ACROSS THE CHARLESTON TRI-COUNTY AREA TO AROUND 90 ACROSS THE FAR SOUTHWEST ZONES. TEMPERATURES ALONG THE BEACHES OF CHARLESTON COUNTY WILL LIKELY ONLY TOP OUT IN THE LOWER 80S. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TONIGHT...ANY SHOWERS/STORMS WILL DIMINISH AND/OR PUSH FARTHER INLAND LEADING TO A RATHER DRY NIGHT WITH LOWS AROUND 70 INLAND AND MID/UPPER 70S NEAR THE COAST. TUESDAY AND TUESDAY NIGHT...A MID AND UPPER LEVEL RIDGE CENTERED OVER THE SOUTHERN PLAINS WILL EXPAND EASTWARD OVER THE REGION. MEANWHILE AT THE SURFACE...THE FORMER BACKDOOR COLD FRONT WILL REMAIN NEARLY STATIONARY IN THE VICINITY OF THE FLORIDA/GEORGIA BORDER AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTHEAST. ONSHORE LOW LEVEL TRAJECTORIES WILL ADVECT MOISTURE INTO THE AREA...ESPECIALLY ACROSS SOUTHEAST GEORGIA WHERE ITS CLOSER PROXIMITY TO THE STALLED FRONT FAVORS THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON. THE LACK OF DEEPER MOISTURE FARTHER TO THE NORTHEAST WILL RESULT IN LESS COVERAGE OF SHOWERS AND THUNDERSTORMS WITH SOME AREAS CLOSER TO THE SOUTH CAROLINA COAST POSSIBLY REMAINING RAIN-FREE. WITH THE LOSS OF DIURNAL HEATING ALL CONVECTION WILL DISSIPATE BY MID-EVENING OR SO. THE COOLER ONSHORE FLOW SHOULD ONLY ALLOW TEMPERATURES TO REACH HIGHS IN THE UPPER 80S TO AROUND 90 INLAND AWAY FROM THE COAST. LOWS TUESDAY NIGHT WILL ACTUALLY BE UNSEASONABLY COOL...IN THE UPPER 60S TO LOWER 70S. WEDNESDAY AND WEDNESDAY NIGHT...A WEAK SHORT WAVE DISTURBANCE WILL PASS MAINLY NORTH OF THE AREA ON WEDNESDAY...BUT CAUSE SOME WEAKNESS ALONG THE EASTERN PERIPHERY OF THE MID AND UPPER LEVEL RIDGE. AT THE SURFACE...HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE NORTHEAST AS THE STALLED FRONT TO THE SOUTH DISSIPATES. DESPITE THE PASSAGE OF THE DISTURBANCE...MODELS ARE IN FAIRLY GOOD AGREEMENT SHOWING LITTLE IN THE WAY OF CONVECTION OVER THE AREA. THE FORECAST WILL INDICATE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER SOUTHEAST GEORGIA AND FAR SOUTHERN SOUTH CAROLINA DURING THE AFTERNOON...MAINLY BECAUSE THE DEEPEST MOISTURE WILL REMAIN OVER THESE AREAS. DAYTIME HIGHS WILL REMAIN IN THE UPPER 80S TO AROUND 90...WITH LOWS WEDNESDAY NIGHT AROUND 70 OR IN THE LOWER 70S INLAND FROM THE BEACHES. THURSDAY...THE MID AND UPPER LEVEL RIDGE WILL EXPAND AND BECOME WEST-EAST ORIENTED OVER THE REGION AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE WESTERN ATLANTIC. THIS IS A MORE TYPICAL SUMMERTIME PATTERN...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED TO OCCUR ALONG AND AHEAD OF THE SEA BREEZE IN THE AFTERNOON AND EARLY EVENING. TEMPERATURES WILL WARM AS THE FLOW BECOMES MORE SOUTHERLY...WITH HIGHS IN THE LOWER 90S AWAY FROM THE COAST. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... MEDIUM RANGE GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH MOST OF THE LONG TERM PERIOD...LEADING TO A HIGHER THAN NORMAL CONFIDENCE FORECAST. AN EXPANSIVE UPPER LEVEL RIDGE WILL PREVAIL OVER THE REGION THROUGH SATURDAY...BEFORE A LONG WAVE TROUGH EXPANDS ACROSS THE EASTERN U.S. LATE IN THE WEEKEND INTO EARLY NEXT WEEK. AT THE SURFACE...ATLANTIC HIGH PRESSURE WILL PREVAIL INTO THE WEEKEND...THEN A BACKDOOR COLD FRONT APPEARS POISED TO AFFECT THE AREA LATE SUNDAY AND MONDAY. CONVECTION WILL BE DIURNALLY DRIVEN THROUGH SATURDAY...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED ALONG AND AHEAD OF THE SEA BREEZE EACH AFTERNOON AND EARLY EVENING. THE PROBABILITY OF SHOWERS AND THUNDERSTORMS SHOULD INCREASE LATE IN THE WEEKEND INTO EARLY NEXT WEEK IN ASSOCIATION WITH THE BACKDOOR COLD FRONT. TEMPERATURES SHOULD BE NEAR NORMAL THROUGH MOST OF THE LONG TERM...WITH THE WARMEST TEMPERATURES LIKELY COMING SATURDAY WITH SOME COMPRESSIONAL HEATING AHEAD OF THE FRONT. && .AVIATION /17Z MONDAY THROUGH FRIDAY/... THERE IS A SMALL RISK THAT AN ISOLATED SHOWER COULD IMPACT KSAV THIS AFTERNOON AS A STALLED FRONT REMAINS TO THE SOUTH. STILL...EXPECT MAINLY VFR CONDITIONS TO PREVAIL AT BOTH KCHS AND KSAV. THE MAIN ISSUE THROUGH THE AFTERNOON WILL REMAIN GUSTY EAST SOUTHEASTERLY WINDS DUE TO THE PINCHED GRADIENT. AS SUNSET NEARS...GUSTS WILL SUBSIDE. OVERNIGHT... SOME LOWER CEILINGS ARE POSSIBLE AT KSAV AS LOW LEVEL MOISTURE POOLS IN THE VICINITY OF THE STALLED FRONT...BUT WILL MAINTAIN VFR CONDITIONS FOR NOW. EXTENDED AVIATION OUTLOOK...ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON/EARLY EVENING AND COULD RESULT IN BRIEF REDUCTIONS IN CEILINGS/VISIBILITIES. OTHERWISE...VFR CONDITIONS ARE EXPECTED TO PREVAIL. && .MARINE... TODAY...A BACKDOOR COLD FRONT NEAR THE SAVANNAH RIVER WILL PUSH SOUTHWARD LEADING TO A SURGE OF EAST/NORTHEAST WINDS...AS HIGH AS 15-20 KT AT TIMES OVER THE SC WATERS. SEAS WILL RESPOND A BIT AS WELL BUT SHOULD STAY 4 FT OR LESS...HIGHEST OFFSHORE. THUS...NO ADVISORIES ARE EXPECTED. TONIGHT...MAINLY EAST WINDS EXPECTED AOB 15 KT AS HIGH PRESSURE REMAINS NORTH OF THE AREA WITH LOW PRESSURE TO THE SOUTH. TUESDAY THROUGH SATURDAY...A BACKDOOR COLD FRONT WILL STALL JUST SOUTH OF THE WATERS INTO WEDNESDAY BEFORE DISSIPATING...MAINTAINING AN ONSHORE FLOW ACROSS THE WATERS. THE FLOW WILL VEER SOUTHERLY LATER IN THE WEEK AS HIGH PRESSURE BUILDS IN FROM THE WESTERN ATLANTIC. IN GENERAL...WINDS SHOULD REMAIN AT OR BELOW 15 KT...HIGHEST NEAR SEABREEZE CIRCULATIONS ALONG THE COAST. SEAS WILL RANGE BETWEEN 1-3 FT...HIGHEST OVER OUTER GEORGIA WATERS. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ ST/JHP
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
240 PM CDT MON AUG 5 2013 .DISCUSSION... 1135 AM CDT NEAR TERM FOCUS REMAINS ON SHRA/TSRA POTENTIAL THROUGH THE REST OF THE DAY. WATER VAPOR IMAGERY SHOWS ONCE SHORTWAVE CROSSING THE LOCAL AREA LATE THIS MORNING WITH THE REMNANTS OF AN MCS MOVING SOUTHEASTWARD WITH IT. THE SOUTHWEST FLANK OF THIS ACTIVITY HAS REMAINED ACTIVE IN TERMS OF MAINTENANCE/REGENERATION OF REFLECTIVITY...AS WELL AS SOME THUNDER...AS IT MOVES FROM SOUTHWESTERN BUREAU COUNTY SOUTHEAST. WITH MID LEVEL MOISTURE TRANSPORT AIMED INTO THIS AREA SUSPECT THAT THIS BETTER ORGANIZED AREA WILL CONTINUE AND MAINLY MOVE JUST SOUTHWEST OF THE CWA OVER THE NEXT FEW HOURS...THOUGH AREAS FROM WEST OF STREATOR TO PONTIAC DOWN TO SOUTHERN FORD COUNTY MAY BE GRAZED BY SOME HEAVIER SHOWERS AND POSSIBLY SOME THUNDER. OTHERWISE EXPECT THE CURRENT AREA OF LIGHT RAIN THE NORTH NORTHEAST OF THE BETTER REFLECTIVITY TO FESTER AS IT MOVES SOUTHEASTWARD AS WELL SO SOME LIGHT RAIN WILL REMAIN CONTINUE GENERALLY ALONG AND SOUTH OF I-88 IN ILLINOIS AND EVENTUALLY INTO NW INDIANA INTO EARLY AFTERNOON BUT COVERAGE OF MEASURABLE PRECIP MAY DIMINISH WITH TIME. GOING THROUGH THE REMAINDER OF THE AFTERNOON...ANOTHER SHORTWAVE IS MOVING ACROSS NORTHERN IOWA. AN MCS CONTINUES TO MOVE ACROSS WESTERN IOWA WITH A SOUTHEAST TRAJECTORY WITH ANOTHER AREA OF SCATTERED CONVECTION BETWEEN MASON CITY AND DECORAH WHICH HAS A MORE EASTERLY MOVEMENT. THE FORCING DRIVING THIS WILL CROSS THE AREA MID TO LATE AFTERNOON AND MUCH OF THIS ACTIVITY MAY REMAIN JUST TO THE NORTH. THE CLOUD SHIELD REMAINS EXTENSIVE ACROSS THE AREA THIS MORNING WHICH HAS TEMPERED WARMING BUT THERE AREA GAPS IN COVERAGE BEHIND THE RAIN CURRENTLY CROSSING THE AREA. THIS MAY ALLOW FOR A CORRIDOR OF DESTABILIZATION ACROSS THE NORTHERN CWA WHICH MAY PROMOTE SOME ADDITIONAL SCATTERED ACTIVITY AS THE NEXT WAVE MOVES THROUGH. STRONG/SEVERE THREAT IS NOT ZERO BUT IS LOW AND VERY CONDITIONAL...HINGING ON POCKETS OF DESTABILIZATION THAT MAY OR MAY NOT MATERIALIZE THIS AFTERNOON. COVERAGE LOOKS SCATTERED SO AM FAVORING HIGH CHANCE POPS ACROSS THE NORTHERN HALF OR SO OF THE AREA FOR THE MID AND LATE AFTERNOON. WITH ANTICIPATION OF MOSTLY CLOUDY SKIES OVER MOST OF THE AREA THROUGH THE AFTERNOON HAVE LOWERED HIGHS A FEW DEGREES FOR MOST AREAS. MDB //PREV DISCUSSION... 355 AM CDT THE PRIMARY FORECAST CONCERN DURING THE PERIOD WILL BE TIMING THE BEST CHANCES FOR SHOWERS AND THUNDERSTORMS TODAY INTO TONIGHT...AND AGAIN LATE TUESDAY AND INTO WEDNESDAY. TEMPERATURES WILL ALSO A SIGNIFICANT CONCERN OVER THE NEXT FEW DAYS...AS PRECIP/CLOUD COVER AND FRONTAL TIMING WILL HAVE LARGE IMPACTS ON HOW WARM WE GET. CURRENTLY...ATTENTION IS TURNED TO THE UPPER LEVEL DISTURBANCE MOVING ACROSS NORTH DAKOTA AND INTO MINNESOTA PER WATER VAPOR IMAGERY. THIS FEATURE IS ALREADY INDUCING DECENT LOWER LEVEL SOUTHERLY FLOW AND GOOD MOISTURE RETURN ACROSS THE UPPER MIDWEST. KOAX 00 UTC RAOB FROM SUNDAY EVENING INDICATED A 1.6 INCH PWAT...AND THIS DEEPER MOISTURE IS CONTINUING TO OVERSPREAD MUCH OF THE MID AND UPPER MISSISSIPPI VALLEY AHEAD OF THIS UPPER LEVEL WAVE. SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED ACROSS SOUTHERN PORTIONS OF MINNESOTA JUST AHEAD OF THE AREA OF BEST MOISTURE TRANSPORT. THIS ACTIVITY IS EXPECTED TO SHIFT EAST-SOUTHEASTWARD ACROSS SOUTHERN WISCONSIN THROUGH THE MORNING AND INTO THE AFTERNOON HOURS. IT APPEARS THAT THE BEST FOCUS FOR ACTIVITY WILL BE IN SOUTHERN WISCONSIN...BUT SOME ACTIVITY WILL LIKELY GET INTO FAR NORTHERN ILLINOIS BY THIS AFTERNOON. THEREFORE...I HAVE CONTINUED TO FOCUS THE HIGHEST POPS FAR NORTH. ADDITIONAL THUNDERSTORM ACTIVITY COULD ALSO DEVELOP THIS AFTERNOON TO THE SOUTH AND WEST OF THE MAIN BATCH OF SHOWERS AND STORMS ACROSS SOUTHERN WISCONSIN AND FAR NORTHERN ILLINOIS. IT APPEARS THAT A WEAK SURFACE BOUNDARY...POSSIBLY THE OUTFLOW FROM THE NORTHERN ACTIVITY...COULD FOCUS THIS ADDITIONAL ISOLATED TO SCATTERED THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING ACROSS NORTHWESTERN AND POSSIBLY NORTH CENTRAL ILLINOIS. CONFIDENCE IN THE EXTENT OF THIS ADDITIONAL STORM DEVELOPMENT IS LOW AT THIS TIME. HOWEVER...IF THIS ACTIVITY DOES DEVELOP WITHIN THIS INCREASINGLY MOIST/UNSTABLE BOUNDARY LAYER...THESE STORMS COULD HAVE A STRONG TO SEVERE THREAT GIVEN THE STRENGTH OF THE DEEP LAYER SHEAR. THIS WILL HAVE TO BE MONITORED THROUGH THE DAY. IT APPEARS A STRONG TO SEVERE THREAT WOULD REMAIN ACROSS MY WESTERN AREAS...NAMELY NORTH CENTRAL ILLINOIS AND POINTS WEST THIS AFTERNOON. THIS ACTIVITY LOOKS TO CONTINUE INTO THE EVENING ACROSS MUCH OF NORTHERN ILLINOIS. AREAS ACROSS NORTHERN ILLINOIS COULD RECEIVE SOME DECENT RAINFALL AMOUNTS OUT OF THIS ACTIVITY. TEMPERATURES TODAY WILL BE TRICKY AS A RESULT OF THIS CLOUD COVER/PRECIPITATION. CURRENT THINKING IS THAT AREAS ALONG AND SOUTH OF INTERSTATE 80 COULD APPROACH THE LOW 80S THIS AFTERNOON...AS THE THREAT FOR PRECIP WILL BE MUCH LOWER THERE. HOWEVER...TO THE NORTH OF THIS...THE FLOW OFF THE LAKE...ALONG WITH MORE THICK CLOUD COVER AND PRECIP WILL LIKELY KEEP THINGS COOLER...ESPECIALLY ACROSS THE FAR NORTH...WERE TEMPERATURES MAY ONLY TOP OUT AROUND 70. ON TUESDAY...THINGS LOOK TO WARM NICELY. TEMPERATURES AT 850 AND 925 MB CONTINUE TO SUGGEST THE MID TO POSSIBLY UPPER 80S FOR DAYTIME HIGHS. THE THREAT FOR WIDESPREAD CONVECTION DURING THE DAY ALSO STILL APPEARS TO BE SOMEWHAT LIMITED...WITH THE POTENTIAL FOR SOME WEAK CAPPING...AND WITH WHAT APPEARS TO BE A DEARTH OF LARGE SCALE FORCING. WITH THIS IN MIND I CONTINUED WITH SLIGHT CHANCE POPS DURING THE DAY...AS ANY DEVELOPMENT WOULD LIKELY BE OF LOW AERIAL COVERAGE. TUESDAY NIGHT AND INTO WEDNESDAY MORNING STILL APPEARS TO BE THE MAIN SHOW. THE MODELS CONTINUE IN GOOD AGREEMENT WITH DIGGING A SIGNIFICANT UPPER LEVEL LOW FROM OVER THE HUDSON BAY...TO THE NORTH CENTRAL CONUS INTO WEDNESDAY. AS THIS OCCURS...THE MODELS ARE INSISTING THAT A A SERIES OF SHORT WAVES ACROSS THE PACIFIC NORTHWEST...WILL BE INGESTED INTO THE STRONG WESTERLIES ACROSS THE NORTHERN CONUS. ALTHOUGH THERE CONTINUES TO BE SOME UNCERTAINTY WITH THE EXTEND OF THUNDERSTORM DEVELOPMENT ACROSS NORTHERN ILLINOIS TUESDAY NIGHT...IT DOES APPEAR THE ASSOCIATED COLD FRONT FROM THIS SYSTEM WILL PUSH ACROSS THE AREA ON WEDNESDAY MORNING/EARLY AFTERNOON. GIVEN THE VERY HIGH THETA E AIR MASS...WITH 1.9+ PWATS...THAT WILL BE IN PLACE WITHIN THE WARM SECTOR OF THIS STORM...A PERIOD OF HEAVY RAINFALL IS POSSIBLE TUESDAY NIGHT INTO WEDNESDAY. THERE COULD ALSO BE A SEVERE THREAT WITH THIS ACTIVITY. THE TIME OF DAY DOES NOT APPEAR TO BE THE MOST FAVORABLE FOR SEVERE STORMS...BUT WITH A MODERATELY UNSTABLE ENVIRONMENT AND DECENT DEEP LAYER SHEAR...THERE IS AT LEAST A CONDITIONAL THREAT FOR SEVERE THUNDERSTORMS PRIOR TO THE FRONTAL PASSAGE WEDNESDAY. THE SURFACE COLD FRONT WILL BRING AN END TO THE THREAT FOR CONVECTION FROM NORTHWEST TO SOUTHEAST ACROSS THE AREA ON WEDNESDAY. IT APPEARS ALTHOUGH COOL AIR WILL BEGIN FILTER IN ACROSS THE AREA DURING THE DAY...TEMPERATURES COULD ONE AGAIN TOP OUT INTO THE 80S BEFORE THE COOLER AIR ARRIVES. SLIGHTLY COOLER AND DRIER WILL AGAIN MAKE A RETURN TO THE AREA FOR A PERIOD LATER IN THE WEEK. HOWEVER...IT APPEARS THE STRONG WESTERLY UPPER FLOW PATTERN COULD DRIVE A FEW ADDITIONAL DISTURBANCES ACROSS CENTRAL ILLINOIS LATER IN THE WEEK. THIS ACTIVITY LOOKS TO LARGELY REMAIN SOUTH OF THE AREA...BUT I DID PUT SOME SLIGHT CHANCE POPS IN FAR SOUTH TO ACCOUNT FOR THIS POSSIBILITY. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * AREA OF -RA CONTINUING TO MOVES SE AWAY FROM CHI AREA EARLY THIS AFTERNOON. * ADDITIONAL SHOWERS LATE AFTERNOON THROUGH MID EVENING WITH MVFR VISIBILITY IN HEAVIER SHOWERS. * ISOLD TS WITHIN AREA OF SHOWERS LATE AFTERNOON INTO EARLY EVENING. * PREVAILING MVFR CONDITIONS DUE VISIBILITY AND CEILINGS DEVELOPING LATE EVENING-OVERNIGHT. //DISCUSSION...UPDATED 18Z... AREA OF -RA COVERAGE CONTINUES TO TO MOVE SE OUT OF N CENTRAL AND NE IL AT MIDDAY. AREA OF OVER THE NE-IA BORDER SHOWED A STRENGTHENING TREND DURING THE MID-LATE MORNING...THOUGH NOW WEAKENING AS OF MIDDAY. MEANWHILE...CONVECTION IN FAR NE IA HAS SHOWN SLOW GROWTH/STRENGTHENING A STRONG JET MAX CONTINUES TO ADVANCE FROM THE EASTERN DAKOTAS ACROSS CENTRAL AND SOUTHERN MN. 925-850HPA THETA E ADVECTION AND CONVERGENCE HIGHLIGHT SOUTHERN WI AND NORTHERN IL FOR CONTINUED CONVECTIVE DEVELOPMENT INTO THE LOCAL AREA MID-LATE AFTERNOON AS A SHORT WAVE TROUGH MOVES TO SE WI AN N CENTRAL IL BY 06.00Z. PARTIAL CLEARING ACROSS SOUTHERN WI AND FAR NORTHERN IL WILL ALLOW DESTABILIZATION AND PROMOTE FURTHER CONVECTIVE DEVELOPMENT DUE TO SURFACE HEATING...THOUGH ONLY EXPECT ISOLD TO WIDELY SCT TS AS WHILE THIS SURFACE HEATING IS OCCURRING BACKING AND INCREASING LOWER AND MID LEVEL FLOW WARMS THESE LEVELS COUNTERING THE DESTABILIZATION FROM THE SURFACE HEATING. LATE THIS EVENING THROUGH DAWN LOW LEVEL MOISTURE WILL BE ABUNDANT AND TRAPPED UNDER AN INVERSION WITH A TOP AROUND 950HPA...WHILE SURFACE WINDS BECOME LIGHT. EXPECT MVFR CONDITIONS TO DEVELOP OVERNIGHT...WITH LOCAL AREAS OF IFR TIL 1-2HR AFTER SUNRISE. TRS //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONTINUED VFR THROUGH MID AFTERNOON. * MEDIUM FOR SHRA AND ISOLD TS LATER AFTERNOON-EARLY EVENING. * MEDIUM FOR LOCAL MVFR WITH LATER AFTERNOON-EARLY EVENING SHRA. * MEDIUM OM MVFR CIGS/VSBYS DEVELOPING LATER EVENING AND PERSISTING INTO MID TUE MORNING...WITH LOCAL IFR. TRS //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT...TSRA LIKELY WITH POSSIBLY BRIEF MVFR/IFR. WEDNESDAY...CHC OF TSRA MAINLY IN THE MORNING. THURSDAY-SUNDAY...VFR LIKELY. MTF && .MARINE... 240 PM...A BROAD WEAK TROUGH EXTENDING ACROSS THE PLAINS FROM A SLIGHTLY STRONGER LOW OVER ONTARIO WILL SLOWLY MOVE EAST ACROSS THE WESTERN LAKES WEDNESDAY...WITH THE LOW OVER ONTARIO SLOWLY MOVING EAST THROUGH MID WEEK. AHEAD OF THIS TROUGH...SOUTHERLY WINDS HAVE INCREASED TO 10-20 KT AND FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR SOME WINDS INTO THE 15-25 KT RANGE THIS EVENING BEFORE SLOWLY DIMINISHING OVERNIGHT. ONCE THE TROUGH/COLD FRONT MOVES ACROSS THE LAKE MIDDAY WEDNESDAY...WINDS WILL SHIFT NORTHERLY WITH A PERIOD OF 10-20 KTS POSSIBLE BUT APPEARS THAT WOULD BE SHORT LIVED AS HIGH PRESSURE SPREADS ACROSS THE LAKES REGION WEDNESDAY NIGHT INTO THURSDAY. THE LOW OVER ONTARIO FINALLY SHIFTS EAST INTO QUEBEC ON FRIDAY...WITH A WEAK COLD FRONT MOVING ACROSS THE WESTERN LAKES FRIDAY NIGHT SHIFTING WINDS BACK NORTHERLY INTO SATURDAY WITH ANOTHER HIGH MOVING ACROSS THE LAKES SATURDAY NIGHT INTO SUNDAY. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 233 PM CDT Mon Aug 5 2013 .DISCUSSION... ISSUED 230 PM CDT Mon Aug 5 2013 Remnants of morning thunderstorm cluster have been skirting the northern part of the forecast area over the last few hours, producing a quarter to half inch of rain near Lacon. The southern MCS has remained well away from us, with just extensive cloud cover in between the two systems. These clouds have kept most areas in the mid to upper 70s as of early afternoon, with some lower 80s occurring in the far eastern CWA where there has been more sunshine today. SHORT TERM...Tonight through Friday... Have largely rain chances from the forecast through early Tuesday, as latest models suggest a similar pattern as to last night, with two convective complexes and our forecast area in between. Rain chances should begin increasing from the southwest by Tuesday afternoon as the remnants of the morning convection creep toward us. A shortwave, current evident on water vapor imagery just north of Montana, will deepen as it swings southeast across the northern tier of states over the next couple days. Associated frontal boundary still on track to sweep across the forecast area Wednesday morning and be past us early in the afternoon. Highest rain chances remain concentrated around this front, although late night timing does not favor significant severe weather chances. Latest SPC convective outlooks only give 5% chances of severe weather Tuesday night over the entire area, and similar values ahead of the front Wednesday morning across the southeast CWA. Frontal boundary still progged to hang up to our south Wednesday night as it parallels the upper flow. General model consensus has it extending from the Ohio Valley into southern Missouri, although the GFS is further north toward the I-70 corridor. The models have been continuing their trend of inching the precipitation back northward, with some influence from another trough swinging through the western Great Lakes late in the week. Will increase PoPs to around 60% in the southeast CWA Thursday night. Confidence further north is a little shakier, with the GFS much more aggressive with surface development as the upper trough approaches, but will have rain chances over most of the remaining CWA Thursday night and in the south half on Friday. LONG TERM...Saturday through Monday... General northwest flow expected to amplify a bit through the weekend as ridging re-establishes itself across the Rockies. Most of the Midwest will be under the influence of high pressure into early next week. However, the longer range models show periodic MCS systems once again along the northern periphery of the ridge. The rain chances in the late period grids are mainly focused across the south and southwest CWA, closer to the MCS track. GEELHART && .AVIATION... ISSUED 1256 PM CDT Mon Aug 5 2013 An area of showers will continue to dissipate as it drops southeastward toward KPIA and KBMI over the next 2 to 3 hours. Based on radar trends...will include a tempo group for showers at KPIA between 18z/19z...but will only include VCSH at KBMI. Further southeast...will maintain dry conditions at the remaining central Illinois terminals. A 4000 to 5000ft overcast will remain in place through much of the day...before gradually dissipating by late afternoon/evening. As skies at least partially clear and winds diminish to less than 5kt...patchy fog may become an issue overnight. HRRR shows fog developing across the western KILX CWA toward midnight...and think that trend will spread further eastward overnight. Have hit fog hardest along/west of I-55 where low-level moisture will be most plentiful...with visbys down to 3SM at both KPIA and KSPI late tonight. Further east...have only reduced visbys to around 5SM at KCMI. Winds will initially be from the south at 10 to 15kt this afternoon...then will become light tonight. Southerly winds of around 10kt will resume by Tuesday morning. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
254 PM EDT MON AUG 5 2013 .UPDATE... THE LONG TERM SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 403 AM EDT MON AUG 5 2013 HIGH PRESSURE WILL REMAIN IN CONTROL ACROSS THE AREA TODAY AS IT MOVES EASTWARD. VERY WEAK DISTURBANCES IN THE PREVAILING NORTHWEST FLOW ALOFT COULD POTENTIALLY SPARK A SHOWER OR STORM TONIGHT...WITH CHANCES INCREASING TOWARD MIDWEEK AS A FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST AND MOVES THROUGH THE AREA. DRY WEATHER AND COOL TEMPERATURES RETURN ONCE AGAIN FOR THE COMING WEEKEND AS ANOTHER DOME OF HIGH PRESSURE SETTLES OVER THE AREA. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1055 AM EDT MON AUG 5 2013 RADAR MOSAIC SHOWS SHOWERS AND THUNDERSTORMS ACROSS NORTHWEST ILLINOIS THAT ARE HEADED SOUTHEAST. CURRENTLY SATELLITE SHOWS MOSTLY CLEAR SKIES ACROSS MUCH OF THE AREA WITH CLOUDS ACROSS NORTHERN ILLINOIS HEADING SOUTHEAST TOWARD CENTRAL INDIANA. RAP AND HRRR SHOW THE AFOREMENTIONED STORMS EITHER STAYING JUST NORTH OF THE FORECAST AREA OR CLIPPING A FEW OF THE NORTHERN COUNTIES. LOOKING AT THE CURRENT MOVEMENT AND LOCATION OF HIGH SURFACE PRESSURE THINK THERE/S AN OUTSIDE CHANCE STORMS COULD SNEAK INTO THE FAR NORTHERN PARTS OF THE AREA LATE THIS AFTERNOON...SO ADDED A SLIGHT CHANCE FOR THUNDERSTORMS THERE FROM 4 PM ON. GOING HOURLY TEMPERATURES ARE ON TRACK FOR FORECAST HIGHS IN THE LOW 80S SO LEFT THEM ALONE. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... ISSUED AT 403 AM EDT MON AUG 5 2013 WILL CONTINUE TO CARRY POPS TONIGHT...BUT SLIGHT CHANCE TO LOW CHANCE AT BEST AS SUPPORT IS WEAK. MODELS HAVE EVEN BACKED OFF OF POTENTIAL FOR TUESDAY...BUT WITH BUFKIT SHOWING SOME MODEST CONVECTIVE INSTABILITY WILL CARRY A 30 POP FOR THUNDERSTORMS. HIGHER POPS REMAIN MERITED...BUT CANNOT GO LIKELY ANY PERIOD OWING TO CONTINUED DIFFERENCES BETWEEN MODELS AND RUN TO RUN INCONSISTENCIES WITH THE RELATIVELY WEAK DISTURBANCES MOVING THROUGH THE AREA. HIGHEST POPS WILL OF COURSE BE WITH THE POTENTIAL FRONT MOVING INTO THE AREA MIDWEEK. ON TEMPS...NEAR TO JUST ABOVE CONSENSUS NUMBERS APPEARS TO FIT BEST WITH 850 TEMP TRENDS ACROSS THE BOARD. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... ISSUED AT 254 PM EDT MON AUG 5 2013 FRONTAL BOUNDARY WILL REMAIN NEARLY STATIONARY ACROSS THE OHIO VALLEY THROUGH FRIDAY WITH A CONTINUED THREAT FOR SCATTERED STORMS AS SURFACE WAVES RIPPLE ALONG THE BOUNDARY. WILL CARRY HIGHEST POPS ACROSS SOUTHERN COUNTIES IN CLOSEST PROXIMITY TO THE EXPECTED LOCATION OF THE FRONT. THE ARRIVAL OF A SECONDARY FRONT DROPPING THROUGH THE REGION FRIDAY NIGHT AND SATURDAY MORNING WILL FINALLY PUSH THE REMNANT BOUNDARY WELL SOUTH OF THE FORECAST AREA. HIGH PRESSURE WILL EXPAND INTO THE REGION...BRINGING COOLER AND MUCH DRIER WEATHER TO CENTRAL INDIANA THROUGH THE WEEKEND. MODEL GUIDANCE NOW HINTING THAT UNSETTLED WEATHER LIKELY TO RETURN FOR EARLY NEXT WEEK AS A WARM FRONT LIFTS NORTH INTO THE REGION ON THE BACK SIDE OF HIGH PRESSURE. WILL INTRODUCE LOW CHANCE POPS ON MONDAY. BUMPED HIGH TEMPS UP A FEW DEGREES FROM ALLBLEND FOR FRIDAY... ESPECIALLY ACROSS THE SOUTH...WITH THE BOUNDARY STILL ACROSS THE REGION. HIGHS WILL FALL BACK INTO THE UPPER 70S AND LOWER 80S FOR THE REMAINDER OF THE LONG TERM. && .AVIATION /DISCUSSION FOR 051800Z TAF ISSUANCE/... ISSUED AT 121 PM EDT MON AUG 5 2013 MVFR CONDITIONS POSSIBLE LATE TONIGHT AND TUESDAY MORNING... ESPECIALLY AT KHUF AND KLAF. INITIAL FOCUS FOR THE FORECAST IS AREA OF SLOWLY WEAKENING SHOWERS PROGRESSING SOUTHEAST ACROSS NORTHERN ILLINOIS. NONE OF THE MODELS CURRENTLY HANDLING THIS AREA OF PRECIP WELL AT ALL. THE AREA OF SHOWERS SHOULD CONTINUE TO WEAKEN OVER THE NEXT FEW HOURS AS VERY LITTLE INSTABILITY PRESENT OVER THE REGION. LIGHT SHOWERS HOWEVER MAY MAKE IT TO KLAF BEFORE COMPLETELY DIMINISHING...AND WILL INTRODUCE A VCSH AT THAT TERMINAL FOR THE NEXT FEW HOURS TO COVER. OUTSIDE OF THE AREA OF PRECIP...MID LEVEL CLOUDS WILL STEADILY EXPAND AND LOWER ACROSS THE FORECAST AREA INTO THE EVENING AS A SERIES OF DISTURBANCES ALOFT DRIFT THROUGH THE AREA. POTENTIAL FOR ADDITIONAL CONVECTIVE DEVELOPMENT INTO TONIGHT...ESPECIALLY OVER NORTHERN PARTS OF CENTRAL INDIANA IN CLOSER PROXIMITY TO THE UPPER FORCING TRACKING THROUGH THE GREAT LAKES. HOWEVER WITH VERY LOW CONFIDENCE IN COVERAGE AND TIMING OF ANY DEVELOPMENT...WILL KEEP FORECAST DRY FOR TONIGHT. DESPITE THE INCREASING CLOUD COVER OVERNIGHT...COMBINATION OF LIGHT SOUTHERLY FLOW AND ADDITIONAL LOW LEVEL MOISTURE WILL PRODUCE POTENTIAL FOR MVFR VISIBILITIES TO DEVELOP TOWARDS DAYBREAK TUESDAY...ESPECIALLY AT KHUF AND KLAF. MODEL SOUNDINGS AND RH PROGS SUGGESTIVE OF INCREASING POTENTIAL FOR MVFR STRATOCU TO ADVECT INTO THE REGION TUESDAY MORNING AS AN UPPER LEVEL WAVE TRACKS INTO THE MID MISSISSIPPI VALLEY BY TUESDAY AFTERNOON. LIGHT S/SW FLOW WILL BE LESS THAN 10KTS THROUGH THE END OF THE FORECAST PERIOD. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...NIELD NEAR TERM...CP SHORT TERM...NIELD LONG TERM....RYAN AVIATION...RYAN VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
121 PM EDT MON AUG 5 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 403 AM EDT MON AUG 5 2013 HIGH PRESSURE WILL REMAIN IN CONTROL ACROSS THE AREA TODAY AS IT MOVES EASTWARD. VERY WEAK DISTURBANCES IN THE PREVAILING NORTHWEST FLOW ALOFT COULD POTENTIALLY SPARK A SHOWER OR STORM TONIGHT...WITH CHANCES INCREASING TOWARD MIDWEEK AS A FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST AND MOVES THROUGH THE AREA. DRY WEATHER AND COOL TEMPERATURES RETURN ONCE AGAIN FOR THE COMING WEEKEND AS ANOTHER DOME OF HIGH PRESSURE SETTLES OVER THE AREA. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1055 AM EDT MON AUG 5 2013 RADAR MOSAIC SHOWS SHOWERS AND THUNDERSTORMS ACROSS NORTHWEST ILLINOIS THAT ARE HEADED SOUTHEAST. CURRENTLY SATELLITE SHOWS MOSTLY CLEAR SKIES ACROSS MUCH OF THE AREA WITH CLOUDS ACROSS NORTHERN ILLINOIS HEADING SOUTHEAST TOWARD CENTRAL INDIANA. RAP AND HRRR SHOW THE AFOREMENTIONED STORMS EITHER STAYING JUST NORTH OF THE FORECAST AREA OR CLIPPING A FEW OF THE NORTHERN COUNTIES. LOOKING AT THE CURRENT MOVEMENT AND LOCATION OF HIGH SURFACE PRESSURE THINK THERE/S AN OUTSIDE CHANCE STORMS COULD SNEAK INTO THE FAR NORTHERN PARTS OF THE AREA LATE THIS AFTERNOON...SO ADDED A SLIGHT CHANCE FOR THUNDERSTORMS THERE FROM 4 PM ON. GOING HOURLY TEMPERATURES ARE ON TRACK FOR FORECAST HIGHS IN THE LOW 80S SO LEFT THEM ALONE. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... ISSUED AT 403 AM EDT MON AUG 5 2013 WILL CONTINUE TO CARRY POPS TONIGHT...BUT SLIGHT CHANCE TO LOW CHANCE AT BEST AS SUPPORT IS WEAK. MODELS HAVE EVEN BACKED OFF OF POTENTIAL FOR TUESDAY...BUT WITH BUFKIT SHOWING SOME MODEST CONVECTIVE INSTABILITY WILL CARRY A 30 POP FOR THUNDERSTORMS. HIGHER POPS REMAIN MERITED...BUT CANNOT GO LIKELY ANY PERIOD OWING TO CONTINUED DIFFERENCES BETWEEN MODELS AND RUN TO RUN INCONSISTENCIES WITH THE RELATIVELY WEAK DISTURBANCES MOVING THROUGH THE AREA. HIGHEST POPS WILL OF COURSE BE WITH THE POTENTIAL FRONT MOVING INTO THE AREA MIDWEEK. ON TEMPS...NEAR TO JUST ABOVE CONSENSUS NUMBERS APPEARS TO FIT BEST WITH 850 TEMP TRENDS ACROSS THE BOARD. && .LONG TERM /THURSDAY THROUGH SUNDAY/... ISSUED AT 249 AM EDT MON AUG 5 2013 ECMWF AND GFS CONTINUE TO INDICATE A COOL NORTHWEST FLOW ALOFT WITH FEW TO NO SHORT WAVE DISTURBANCES PASSING THROUGH THE FLOW INTO THE OHIO VALLEY. AT THE SURFACE A WEAK COLD FRONT IS EXPECTED TO BE PUSHING THROUGH AND EXITING THE AREA ON THURSDAY AND FRIDAY. BY FRIDAY AFTERNOON STRONG SURFACE HIGH PRESSURE LOOKS TO BE IN PLACE PROVING ANOTHER DRY WEEKEND WITH ANOTHER ROUND OF BELOW NORMAL TEMPERATURES. && .AVIATION /DISCUSSION FOR 051800Z TAF ISSUANCE/... ISSUED AT 121 PM EDT MON AUG 5 2013 MVFR CONDITIONS POSSIBLE LATE TONIGHT AND TUESDAY MORNING... ESPECIALLY AT KHUF AND KLAF. INITIAL FOCUS FOR THE FORECAST IS AREA OF SLOWLY WEAKENING SHOWERS PROGRESSING SOUTHEAST ACROSS NORTHERN ILLINOIS. NONE OF THE MODELS CURRENTLY HANDLING THIS AREA OF PRECIP WELL AT ALL. THE AREA OF SHOWERS SHOULD CONTINUE TO WEAKEN OVER THE NEXT FEW HOURS AS VERY LITTLE INSTABILITY PRESENT OVER THE REGION. LIGHT SHOWERS HOWEVER MAY MAKE IT TO KLAF BEFORE COMPLETELY DIMINISHING...AND WILL INTRODUCE A VCSH AT THAT TERMINAL FOR THE NEXT FEW HOURS TO COVER. OUTSIDE OF THE AREA OF PRECIP...MID LEVEL CLOUDS WILL STEADILY EXPAND AND LOWER ACROSS THE FORECAST AREA INTO THE EVENING AS A SERIES OF DISTURBANCES ALOFT DRIFT THROUGH THE AREA. POTENTIAL FOR ADDITIONAL CONVECTIVE DEVELOPMENT INTO TONIGHT...ESPECIALLY OVER NORTHERN PARTS OF CENTRAL INDIANA IN CLOSER PROXIMITY TO THE UPPER FORCING TRACKING THROUGH THE GREAT LAKES. HOWEVER WITH VERY LOW CONFIDENCE IN COVERAGE AND TIMING OF ANY DEVELOPMENT...WILL KEEP FORECAST DRY FOR TONIGHT. DESPITE THE INCREASING CLOUD COVER OVERNIGHT...COMBINATION OF LIGHT SOUTHERLY FLOW AND ADDITIONAL LOW LEVEL MOISTURE WILL PRODUCE POTENTIAL FOR MVFR VISIBILITIES TO DEVELOP TOWARDS DAYBREAK TUESDAY...ESPECIALLY AT KHUF AND KLAF. MODEL SOUNDINGS AND RH PROGS SUGGESTIVE OF INCREASING POTENTIAL FOR MVFR STRATOCU TO ADVECT INTO THE REGION TUESDAY MORNING AS AN UPPER LEVEL WAVE TRACKS INTO THE MID MISSISSIPPI VALLEY BY TUESDAY AFTERNOON. LIGHT S/SW FLOW WILL BE LESS THAN 10KTS THROUGH THE END OF THE FORECAST PERIOD. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...NIELD NEAR TERM...CP SHORT TERM...NIELD LONG TERM....PUMA AVIATION...RYAN VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1252 PM CDT MON AUG 5 2013 .SYNOPSIS... ISSUED AT 348 AM CDT MON AUG 5 2013 LATEST SFC ANALYSIS WAS INDICATING DEPARTING HIGH PRESSURE CENTERED OVER LOWER MI INTO NORTHWESTERN OH...WHILE RETURN FLOW CONTINUED TO ORGANIZE UP THE PLAINS AND JUST EAST OF THE MO RVR VALLEY. UPPER 60 TO AROUND 70 SFC DPTS WERE WRAPPING UP AROUND THE WESTERN FLANK OF THE RIDGE FROM THE LOWER MS RVR VALLEY...UP ACRS NEB. CURRENT MESOANALYSIS WAS INDICATING ELEVATED PLUME OF HIGHER THTA-E AIR GENERALLY ACRS THE SAME REGIONS...MAYBE GETTING PUSHED A BIT FURTHER EAST AND NORTHEAST OF THE THE SFC LAYER ACRS THE WESTERN THIRD OF IA. ALOFT...NORTHWEST FLOW CONTINUED WITH AN EMBEDDED WAVE PUSHING ACRS NORTHWESTERN INTO WEST CENTRAL MN DRIVING MAINLY AN ELEVATED MCS ACRS THE SOUTHEAST HALF OF MN. THIS ACTIVITY DROPPING SOUTHEAST ALONG THTA-E GRADIENT AND SHOULD MAKE IT INTO THE NORTHWESTERN AND NORTHERN PORTIONS OF THE DVN CWA THIS MORNING...POSSIBLY INDEPENDENCE BY 1030Z. OTHER STRONG THTA-E ADVECTION AND CONVERGENT FIELDS WERE FUELING HEAVY CONVECTIVE BANDS ACRS KS INTO SOUTHERN MO. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 348 AM CDT MON AUG 5 2013 TODAY...WILL WALK IN PORTION OF THE UPSTREAM MN/IA BORDER MCS INTO THE NORTHWESTERN TO NORTHERN THIRD OF THE DVN CWA THIS MORNING... BUT AS IT GETS AWAY FROM BETTER SUPPORT/H85 JET THTA-E FEED FEEL THE GENERAL WEAKENING TREND THAT THE LATEST RUN HRRR SUGGESTS WILL VERIFY AS IT SPILLS ALONG AND SOUTH OF HWY 30 AFTER 12Z THROUGH 14Z. BUT MAY STILL HAVE TO WATCH FOR A STRONG STORM IN THE FAR NORTHWESTERN CWA AS IT ARRIVES THOUGH AROUND 515 TO 530 AM CDT. WILL THEN WALK THE REST OF THE MCS AGAIN PROBABLY IN A DIURNALLY WEAKENING MODE ACRS THE NORTHERN THIRD OR A LITTLE MORE OF THE DVN CWA THROUGH LATE MORNING WITH HIGHEST POPS NORTH OF HWY 30. THEN AS CONVECTIVE DEBRIS CLEARS AND WARM AIR/THTA-E ADVECTION CONTINUE ACRS THE AREA INTO THE AFTERNOON...PORTIONS OF THE DVN CWA MAY BECOME RELATIVELY UNSTABLE ESPECIALLY THE SOUTHWESTERN HALF. REMNANT OUTFLOW BOUNDARIES AND A SECONDARY TYPE WARM FRONT MAY LAY OUT ACRS THE AREA AND ACT AS POTENTIAL FOCAL POINTS FOR AFTERNOON AND EARLY EVENING CONVECTION TO REFIRE ON. SOUTHERN PORTION OF THE NW MN WAVE AND RATHER VIGOROUS MID/UPPER JET STREAKS STREAMING ALONG AND JUST NORTH OF THE AREA COULD KICK OFF SCTRD STORMS THIS AFTERNOON WITH AN ISOLATED THREAT OF STRONG TO SVR STORMS LIKE SPC IS HINTING AT DUE TO INCREASING VERTICAL SHEAR PROFILES. BUT MUCH WILL DEPEND ON EVENTUAL HIGH TEMPS AROUND 80 OR WARMER AND IF SFC DPTS CAN MAKE IT AT LEAST INTO THE UPPER 60S. WILL GO WITH LOW TO MODERATE CHC POPS THIS AFTERNOON BECAUSE OF COVERAGE/INSTABILITY CONCERNS. HIGHS COOLER IN THE MID TO UPPER 70S IN THE NORTHEASTERN THIRD...TO THE LOW TO MID 80S IN THE SOUTHWEST WITH INCREASING BOUNDARY LAYER HUMIDITY. TONIGHT...WITH THE WAVE/VORT MAX SHEARING OFF TO THE EAST OF THE AREA...END OF LIFTING MECHANISMS AND DIURNAL PROCESSES SHOULD BRING ABOUT A DECREASE OF ANY PRECIP ACTIVITY AS THE EVENING PROGRESSES. NOCTURNAL LLJ PROGGED TO FOCUS BACK TO THE WEST AND SOUTH OF THE AREA AS WELL. WITH HIGHER DPTS IN PLACE AND LIGHT VARIABLE FLOW... ANY CLOUD CLEAR OUT MAY FOSTER FOG PRODUCTION ESPECIALLY IN AREAS THAT MANAGE TO GET SOME NEEDED RAINFALL. FOR NOW WILL JUST BLANKET THE CWA WITH PATCHY LATE NIGHT FOG WORDING. LOWS IN THE MID TO UPPER 60S IN MOST OF THE LOCAL FCST AREA. ..12.. .LONG TERM...(TUESDAY THROUGH NEXT SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 A SHORT WAVE AND COOL FRONT MOVING OUT OF THE NORTHERN PLAINS TUESDAY AND THROUGH THE MID AND UPPER MISSISSIPPI VALLEY BY WEDNESDAY MORNING WILL BRING A CHANCE OF THE THUNDERSTORMS TO THE REGION. TEMPERATURES AHEAD OF THE FRONT SHOULD RISE INTO THE 80S WITH DEWPOINTS IN THE UPPER 60S AND LOW 70S. SURFACE BASED CAPES BY MID AFTERNOON ARE EXPECTED TO BE AROUND 2K J/KG OVER MOST OF THE AREA. WITH THE INSTABILITY IN PLACE AND SOME WEAK UPPER FORCING SPREADING IN AHEAD OF THE MAIN SHORTWAVE...SOME ISOLATED TO SCATTERED STRONG STORMS WILL BE POSSIBLE DURING THE AFTERNOON AND HAVE INCLUDED SLIGHT CHANCE TO LOW CHANCE POPS FOR THE ENTIRE AREA AFTER 18Z. THE MAIN FORCING IS PROGGED TO MOVE THROUGH LATE TUESDAY NIGHT AND HAVE KEPT HIGH CHANCE TO LIKELY POPS DURING THIS PERIOD. THERE SHOULD BE ENOUGH INSTABILITY WITH MODERATE DEEP LAYER SHEAR FOR A RISK OF SEVERE STORMS OVERNIGHT. THE FRONT AND UPPER WAVE WILL BE EAST OF THE AREA BY WEDNESDAY MORNING BUT THE LOW LEVEL MOISTURE WILL BE SLOW TO LEAVE IN THE WEAK FLOW BEHIND THE FRONT SO HELD ON TO SOME LOW POPS EAST AND SOUTH WEDNESDAY. FOR THE REST OF THE FORECAST PERIOD NORTHWEST FLOW WILL REMAIN IN PLACE KEEPING MAINLY DRY AND COOLER THAN NORMAL CONDITIONS OVER THE AREA. THE MODELS ARE SHOWING A COUPLE OF WAVES MOVING OUT OF THE SOUTHERN ROCKIES AND THROUGH THE MID AND LOW MISSISSIPPI VALLEY WEDNESDAY THROUGH FRIDAY. THE NORTHERN EDGE OF THE PRECIPITATION BRUSHES THE FAR SOUTHERN COUNTIES SO KEPT SOME SLIGHT CHANCE POPS GOING IN THE SOUTH MID TO LATE WEEK. BROAD BRUSH SLIGHT CHANCE POPS WERE PLACED OVER THE FORECAST AREA FOR SUNDAY WITH THE ECMWF SHOWING A SHORT WAVE MOVING OUT OF THE NORTHERN PLAINS INTO THE UPPER MS VALLEY SUNDAY AND SUNDAY NIGHT. DLF && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1238 PM CDT MON AUG 5 2013 MORNING SHOWERS/STORMS ARE CURRENTLY EXITING TO THE EAST WITH LOW LEVEL CLOUDINESS CIGS 1-3K AGL IN ITS WAKE...WHICH HAVE BEEN GRADUALLY LIFTING. IMPULSE WILL MOVE ACROSS THE AREA THIS AFTERNOON/EARLY EVENING WITH A LOW PROBABILITY FOR SOME SHOWER/STORM ACTIVITY. LEFT OUT OF TAFS FOR NOW AND WILL AMEND AS SEE FIT. BEST AREAS FOR POSSIBLE CONVECTION IS NEAR THE BRL AND POSSIBLY CID AND MLI SITES. CLEARING AND LIGHT WINDS WILL BE COMMON BY MID EVENING...ALLOWING FOR FOG AND LOW CLOUDS OVERNIGHT AND TUESDAY AM. FOR NOW BROUGHT VSBYS DOWN TO 1 SM AND CIGS TO 1K FT AGL AFTER 08Z...BUT FEEL THIS MAY NOT BE LOW ENOUGH. WINDS WILL REMAIN SOUTHERLY AT 7-12 KTS...DIMINISHING TO NEARLY CALM BY MID TO LATE EVENING. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...12 SHORT TERM...12 LONG TERM...DLF AVIATION...14
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
534 PM EDT MON AUG 5 2013 .SYNOPSIS... HIGH PRESSURE AT THE SURFACE WILL PROMOTE A DRY AND GENERALLY SUNNY DAY. A SLOW-MOVING UPPER-LEVEL DISTURBANCE WILL BE ACCOMPANIED BY INCREASING TEMPERATURES AND ACTIVE WEATHER TUESDAY THROUGH THURSDAY. && .NEAR TERM /THROUGH TUESDAY/... WITH 530PM UPDATE...HAVE BACKED OFF POPS A LITTLE BIT MORE DURING THE OVERNIGHT HOURS. THE LATEST RUNS OF BOTH THE RAP AND THE HRRR MODELS DO NOT SHOW ANY PRECIPITATION DURING THAT TIME PERIOD...BUT HAVE STILL LEFT SOME SLIGHT CHANCE POPS FOR CONSISTENCY. PREVIOUS DISCUSSION FOLLOWS. GUIDANCE HAS TRENDED CONSISTENTLY DRIER OVNGT TNGT. BUT INCRD WEAK FORCING AND MODEST MOISTURE ADVCTN COULD HELP ERADICATE SOME OF THE DRY AIR. THUS...POPS GENLY WERE LMTD TO SLGT CHC THRU MUCH OF TNGT. POPS WERE INCRD TO CHC VERY LATE TNGT IN A PORTION OF THE FCST AREA...WHERE BEST OPPORTUNITY FOR MOISTENING OF THE COLUMN WILL BE. MIXED SUN AND CLDS WILL CONT THRU TUE WITH LOW CHCS FOR PCPN OWING TO LMTD DP MSTR. ANY SHWRS ASSOCIATED WITH SHRTWV TROF PASSAGE WILL BE SCT IN CVRG AND WILL TRANSLATE INTO ERN ZONES BY LATE TUE AFTN. MAXIMA WILL BE NR NRML IN THE UPR 70S- LWR 80S. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... A WK SHRTWV WL EXIT THE RGN TUE NGT WITH DCRG SHWR CHCS. ANOTHER SHRTWV WL MOVE ACRS THE RGN WED AHD OF AN APRCHG CDFNT. MAINTAINED LIKELY POPS ACRS THE AREA FOR SHWRS AND PSBL TSTMS. CAPES 1000-1500 J/KG EXPD WITH SOME INCR IN SHEAR AS WELL...ALTHOUGH SVR POTENTIAL APPEARS LOW ATTM. PWATS WL BE INCRG BUT APPEARS TO BE NO WDSPRD FLOODING CONCERNS ATTM AS WELL. THE CDFNT SHOULD DRIFT SEWD ACRS THE AREA LT WED NGT INTO THU WITH BEST CHC POPS S AND E OF PIT. TEMPS EXPD TO BE NR SEASONAL AVGS. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A WAVE IS EXPD TO MOVE E THRU THE OH VLY ALG A STALLED CDFNT THU NGT INTO FRI...KEEPING SHWR AND TSTM CHCS IN THE FCST. A SECONDARY CDFNT SHOULD PUSH S OF THE RGN FRI NGT...RETURNING DRY WEA AND BLO AVG TEMPS FOR THE WEEKEND INTO ERLY NXT WK. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... DRY LOW-LVL AMS AND INCRG CLD CVR WILL LMT RESTRICTIONS TNGT. IF ANY FOG DVLPS...IT LKLY WILL BARELY BROACH MVFR CATEGORY. THERE IS A SMALL PSBLTY OF LGT RAIN AT KFKL...BUT DRY COLUMN SHOULD LMT POTL. GENLY VFR CONDS XPCD TUE. SCT SHWRS MAY DVLP TUE AFTN AS WEAK SHRTWV TROF CROSSES THE RGN. BRIEF RESTRICTIONS WILL BE PSBL IN ANY SHWRS...BUT CHC OF IMPACTING ANY PARTICULAR TERMINAL IS LOW. OUTLOOK.../TUESDAY THROUGH SATURDAY/... OCNL RESTRICTIONS IN SHWRS AND TSTMS PSBL WED-THU. LOW-LVL MSTR WILL INCR SGFNTLY WED-THU...LEADING TO PSBL RESTRICTIONS IN OVNGT FOG. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
138 PM EDT MON AUG 5 2013 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 334 AM EDT MON AUG 5 2013 CLOUDS WILL BE ON THE INCREASE THIS MORNING...AND RAIN WILL SPREAD IN ACROSS THE AREA THIS AFTERNOON AND EARLY THIS EVENING. RAIN IS THEN EXPECTED TO REMAIN OVER THE AREA FOR A GOOD PORTION OF THE NIGHT TONIGHT. THERE WILL BE A LOW CHANCE OF A THUNDERSTORM TONIGHT...HOWEVER MOST AREAS WILL NOT SEE ONE AND SEVERE WEATHER IS NOT EXPECTED. ANOTHER BETTER CHANCE OF SHOWERS AND STORMS WILL COME DURING THE TUESDAY NIGHT AND WEDNESDAY TIME FRAME AHEAD OF AND ALONG A COLD FRONT THAT WILL MOVE THROUGH THE AREA. DRIER AIR CAN BE EXPECTED FOR THE END OF THE WEEK. && .UPDATE... ISSUED AT 1153 AM EDT MON AUG 5 2013 BACKED OFF ON THE CHANCES FOR SHOWERS THIS AFTERNOON JUST A BIT. DRIER AIR IS WINNING THE BATTLE AT THE MOMENT WITH MUCH OF THE PRECIP DIMINISHING IN AREAL EXTENT AND INTENSITY AS TO MOVES INTO LOWER MI. THERE MAY BE A DECENT LULL THROUGH THE EARLY TO MID AFTERNOON HOURS. THE EXPECTATION IS THAT WE WILL SEE PRECIPITATION BECOME MORE WIDESPREAD IN THE LATE AFTERNOON THOUGH AND INTO THE EVENING HOURS. THE HRRR SHOWS A LITTTLE LESS PRECIPITATION THAN IT DID A FEW HOURS AGO BUT STILL SHOWS RAIN SHOWERS EXPANDING IN COVERAGE TOWARDS 00Z. SO...CHANCE TYPE POPS FOR RAIN SHOWERS INTO MID AFTERNOON BECOMING LIKELY TOWARDS EVENING. MODELS SHOW A GOOD INFLUX OF MOISTURE IN THE LOWER LEVELS WHICH IS WHY WE EXPECT PRECIP TO EXPAND LATER. 850MB MOISTURE TRANSPORT INCREASES AS DOES ISENTROPIC LIFT ON THE 305K SURFACE LATER THIS AFTERNOON. SOLID LIFT ON THE 305K SURFACE IS SEEN AT 00Z WITH CONDENSATION PRESSURE DEFICITS NEAR 0MB/S. SOME BREAKS IN THE OVERCAST WILL BE POSSIBLE THIS AFTERNOON. THE BREAKS COMBINED WITH A LITTLE LESS PRECIPITATION IS WHY WE HAVE NUDGED HIGH TEMPS UP SLIGHTLY IN ALL AREAS. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 334 AM EDT MON AUG 5 2013 THE TWO MAIN PERIODS OF CONCERN ARE RAIN CHANCES THIS AFTERNOON AND TONIGHT...AND THEN CONVECTIVE POTENTIAL TUE NIGHT AND WED. THE MAIN CHANGES TO THE FCST ARE AN INCREASE IN RAIN CHCS THIS AFTERNOON/ TONIGHT AND ALSO DROPPING TEMPS A BIT TODAY AS A RESULT OF THE HIGHER CONFIDENCE OF THE RAIN. AS MENTIONED ABOVE...CONFIDENCE HAS INCREASED A DECENT AMOUNT THAT MOST OF THE AREA WILL SEE A DECENT RAINFALL LATER THIS AFTERNOON AND TONIGHT. MOST OF THE MODELS HAVE FOLLOWED THE EURO IN BRINGING THE SHORT WAVE NOW ACROSS ERN NORTH DAKOTA AS OF 07Z TOWARD THE CWFA LATER TODAY AND TONIGHT. CONVECTION HAS BLOWN UP ACROSS SRN MN AS EXPECTED THIS MORNING AT THE NOSE OF THE LLJ/MOISTURE TRANSPORT JUST AHEAD OF THE WAVE. THE WAVE IS NOT EXPECTED TO LOSE ITS PUNCH AS QUICKLY...AND THE LLJ/MOISTURE TRANSPORT AXIS WILL SHIFT TO LAKE MICHIGAN BY 00Z. WE WILL LIKELY SEE THE SHOWERS OUT AHEAD OF IT TRAVEL VIA THE FAST MID LEVEL FLOW INTO THE AREA A BIT EARLIER AHEAD OF THE LLJ. IT APPEARS THAT RAIN WILL APPROACH THE COAST BY 18Z...AND SHOULD OVERSPREAD A GOOD MAJORITY OF THE CWFA BY 00Z TONIGHT. FOR THIS REASON...WE BELIEVE TEMPS WILL RISE QUICKLY TO AROUND 70 BY THE TIME THE RAIN MOVES IN...BEFORE FALLING ONCE THE RAIN GET HERE. THE INSTABILITY DOES NOT FOLLOW AS QUICKLY...AND WEAKENS BY THE TIME IT GETS HERE AFTER 03Z TONIGHT AS THE SHORT WAVE BEGINS TO ENTER THE AREA. EVEN WHEN IT DOES ARRIVE...IT WILL LIKELY ONLY PRODUCE ISOLATED STORMS AS LI/S ARE JUST A TOUCH BELOW ZERO C. DUE TO THE LACK OF INSTABILITY BOTH AT THE SFC AND ALOFT...WE DO NOT EXPECT ANY SEVERE WEATHER EVEN WITH GOOD SHEAR VALUES. THE RAIN SHOULD MOVE OUT BY 12Z TUE AS THE SHORT WAVE SHOULD BE READY TO EXIT THE CWFA BY THAT TIME. WE SHOULD SEE A RELATIVE LULL IN PCPN WITH SOME SHORT WAVE RIDGING EXPECTED IN THE WAKE. THE SFC FRONT WILL BE JUST SOUTHWEST OF THE AREA...AND WE COULD SEE WEAK SHORT WAVES IN THE FAST FLOW ALOFT POTENTIALLY TOUCH OFF ADDITIONAL SHOWERS AND STORMS. THE NEXT BEST CHC OF ADDITIONAL SHOWERS AND STORMS WILL COME DURING THE SECOND HALF OF TUE NIGHT AND WED MORNING ACROSS THE AREA. THIS WILL OCCUR AS A BETTER DEFINED SHORT WAVE IS EXPECTED TO DIVE SE OUT OF CANADA AND INTO THE UPPER MIDWEST TUE NIGHT. AHEAD OF THE SHORT WAVE...WE WILL SEE THE LLJ HELP TO FIRE CONVECTION TO OUR WEST NEAR THE QUAD CITIES AND THEN MOVE IN VIA THE MEAN WRLY FLOW ALOFT. IF THINGS EVOLVE THIS WAY...THIS SHOULD LIMIT THE CONVECTIVE/SEVERE POTENTIAL ON WED AS THE FRONT MOVES THROUGH AS IT WILL LIMIT THE HEATING AHEAD OF THE FRONT. CONVECTION WILL REMAIN POSSIBLE INTO WED AFTERNOON BEFORE THE FRONT EXITS BY 00Z THU. .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 334 AM EDT MON AUG 5 2013 THE THEME OF SLIGHTLY BELOW NORMAL TEMPERATURES WILL CONTINUE THROUGH NEXT WEEKEND AS THE PERSISTENT/LARGE VORTEX REMAINS OVER EASTERN CANADA. WILL GO WITH A DRY FORECAST ON WEDNESDAY NIGHT AND THURSDAY AS CURRENT INDICATIONS ARE THAT THE COLD FRONT WILL BE EAST OF THE AREA WITH HIGH PRESSURE BUILDING IN. THE UPPER LOW WHICH DROPS SOUTH TOWARD THE LAKE SUPERIOR REGION LATE IN THE WEEK SHOULD SEND ANOTHER COLD FRONT THROUGH LWR MI ON FRIDAY NIGHT. HOWEVER AHEAD OF THAT FRONT ON FRIDAY H8 TEMPS NEAR 15C TRY TO SNEAK IN. GIVEN ENOUGH SUNSHINE... WE COULD TOP 80 DEGREES FRIDAY AFTERNOON. WILL CARRY A SLIGHT CHANCE OF RAIN SHOWERS WITH THE COLD FRONT ON FRIDAY NIGHT... ALTHOUGH THE COLD AIR BEHIND IT DOES NOT APPEAR TO LINGER TOO LONG SINCE THE UPPER LOW LIFTS OUT OVER THE WEEKEND AND THE FLOW ALOFT GOES ZONAL AGAIN FOR A FEW DAYS. THAT IMPLIES THAT TEMPERATURES NEXT WEEKEND WILL NOT BE TOO MUCH BELOW NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 138 PM EDT MON AUG 5 2013 AN UPPER LEVEL LOW WILL CAUSE SHOWER TO DEVELOP LATE THIS AFTERNOON ACROSS THE CWA. REGIONAL NEPH ANALYSIS SHOWS A SHARP DROP FROM VFR TO MVFR OVER EASTERN/CENTRAL WISCONSIN. LOOK FOR A SIMILAR FALLOFF IN CIGS OVER THE TAF SITES THIS EVENING. LOOKING AT MVFR/IFR FOR MUCH OF THE PERIOD. && .MARINE... ISSUED AT 334 AM EDT MON AUG 5 2013 NO MARINE HEADLINES WILL BE REQUIRED WITH THIS FCST PACKAGE. AFTER A BREAK IN THE WINDS EARLY THIS MORNING...WINDS WILL COME BACK UP A BIT TODAY. THIS TIME THEY WILL HAVE A SRLY COMPONENT TO THEM...OUT AHEAD OF THE NEXT INCOMING SYSTEM. SOME LOCATIONS UP NORTH COULD INITIALLY SEE SOME WINDS UP TO 20 KNOTS. SRN LOCATIONS COULD THEN SEE SOME WINDS APPROACH 20 KNOTS TONIGHT AS THE LOW LEVEL JET PASSES ACROSS THOSE AREAS. WINDS WILL DIMINISH ON TUE...ONLY TO COME UP TUE NIGHT AND EARLY WED AHEAD OF THE NEXT FRONT. && .HYDROLOGY... ISSUED AT 334 AM EDT MON AUG 5 2013 WE ARE NOT EXPECTING ANY FLOODING AT THIS TIME...HOWEVER IT DOES LOOK LIKE THE AREA WILL SEE SOME BENEFICIAL RAINS THIS WEEK THROUGH WED. THE AREA OF RAINFALL EXPECTED THIS AFTERNOON AND TONIGHT ALMOST APPEARS TO BE A GOOD SOAKING RAIN. PRECIPITABLE WATERS COME UP A BIT TO AROUND 1.5 INCHES. THIS IS NOT ABNORMALLY HIGH FOR THIS TIME OF THE YEAR. WE ARE EXPECTING THAT MANY LOCATIONS WILL SEE UP TO 0.75 INCHES OF RAIN THROUGH TONIGHT. THE NEXT BATCH OF RAIN WOULD LIKELY BE TUE NIGHT AND WED AS THE NEXT FRONT APPROACHES THE AREA. RAIN AMOUNTS THEN ARE STILL A BIT UNCERTAIN...BUT SOME HEAVIER DOWNPOURS WILL BE POSSIBLE THEN WITH MORE CONVECTION POSSIBLE COMPARED TO TONIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ UPDATE...DUKE SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...MEADE AVIATION...93 HYDROLOGY...NJJ MARINE...NJJ
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1259 PM CDT MON AUG 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 330 AM CDT MON AUG 5 2013 A 30 KT LLJ NOSING UP INTO SW MN EARLY THIS MORNING HAS FORCED A FAIRLY BROAD SHIELD OF SHOWERS WITH EMBEDDED THUNDERSTORMS THAT HAS BEEN STEADILY MAKING ITS WAY ACROSS MN THIS MORNING. ELEVATED INSTABILITY HAS NOT MADE MUCH PROGRESS NE THOUGH...WHICH IS WHY ANY DEEPER CONVECTION HAS ESSENTIALLY BEEN CRAWLING AROUND THE MPX CWA BORDER WITH FSD. MOST OF THE HOPWRF MEMBERS ALONG WITH THE LOCAL MPX-WRF HAVE ALL DONE A DECENT JOB IN CAPTURING WHAT HAS HAPPENED SO FAR OVERNIGHT IN TERMS PRECIP PLACEMENT...THEY HAVE ALL JUST BEEN ABOUT 2 HOURS BEHIND SCHEDULE. AS A RESULT...WAS FAIRLY AGGRESSIVE WITH MOVING LIKELY OR BETTER POPS OUT OF THE AREA THIS MORNING. BASED ON CURRENT MOVEMENT...BACK EDGE OF THE SHOWERS OVER CENTRAL MN WILL BE CLEARING THE EAU AREA AROUND 11Z...SO CERTAINLY DOES NOT MAKE MUCH SENSE TO HAVE MUCH IN THE WAY OF POPS BEYOND 15Z. THE ONLY POTENTIAL PROBLEM FOR THIS FASTER PROGRESSION OF LOWER POPS THROUGH THE AREA IS THE FACT THAT THERE IS A SFC TROUGH/COLD FRONT FEATURE CURRENTLY MOVING THROUGH THE ERN DAKOTAS THAT THE HRRR IS TRYING TO DEVELOP ANOTHER LINE OF CONVECTION ALONG LATER THIS MORNING. HAVE SEEN A FEW SPECKLES ON THE RADAR TO THE WEST OF THE MAIN PRECIP SHIELD OVER WRN MN...BUT TO THIS POINT WE HAVE NOT SEEN ANYTHING TO SUGGEST STORMS ON THE ORDER OF THE WHAT THE 5Z AND 6Z VERSIONS OF THE HRRR HAVE BEEN SHOWING DEVELOPING NEAR THE MN/SD. WITH MAIN PUSH OF MOISTURE TRANSPORT FOLLOWING THE PRECIP SHIELD EAST AND WITH AT LEAST SOME DEGREE OF OVERTURNING OCCURRING WITH THE FIRST ROUND OF RAIN...HAVE FAVORED THE FASTER DEPARTURE OF PRECIP...THOUGH THIS MAY NEED TO BE CHANGED BEFORE RUNNING OUT THE DOOR AT 6 AM. FOR THIS AFTERNOON...BIG CHANGE TO THE FORECAST WAS TO BOOST HIGHS A FEW DEGREES...MAINLY OVER MN. BASED ON THE HOPWRF...ALONG WITH THE RAP...EXPECT SKIES TO OPEN UP PRETTY GOOD BY THIS AFTERNOON BEHIND THIS MORNINGS ACTIVITY. WITH H85 TEMPS IN THE NEIGHBORHOOD OF 16C...THIS WOULD FAVOR MIXING DOWN HIGHS INTO THE LOW TO MID 80S ACROSS MN. HELD HIGHS IN THE 70S ACROSS WI WHERE CLOUD COVER WILL BE MORE PERSISTENT. OF COURSE IF THE CLOUDS DO NOT CLEAR OUT AS PLANNED...THEN IT WILL BE A SECOND DAY IN A ROW WHERE CLOUDS RESULT IN A FORECAST THAT IS A BIT OVERDONE ON THE HIGHS.... FOR THIS AFTERNOON...THAT AFOREMENTIONED DAKOTAS THROUGH WILL MEANDER OVER TO NEAR THE MN/WI BORDER. THE GFS DEVELOPS UP TO 1000 J/KG OF MLCAPE OUT AHEAD OF THIS BOUNDARY...WHICH MAY BE ENOUGH TO GENERATE SOME ISO/SCT STORMS. HOWEVER...BEHIND THIS MORNINGS WAVE...ALL MODELS SHOW SOME PRETTY EXTENSIVE DRYING AND SUBSIDENCE IN THE MID-LEVELS. NAM/RAP SOUNDINGS SHOW A DECENT SUBSIDENCE INVERSION DEVELOPING AROUND H7 AS WELL. ALL OF THIS POINTS TO WHAT SHOULD BE A DRY DAY...THOUGH WITH INSTABILITY FORECAST TO BE IN PLACE...CAN NOT COMPLETELY RULE OUT SOME DIURNALLY DRIVEN THUNDERSTORM ACTIVITY DEVELOPING...SO HAVE LEFT SOME 20-30 POPS IN PLACE THIS AFTERNOON FOR ERN MN INTO WRN WI. FOR TONIGHT...THE MPX AREA LOOKS TO BE CAUGHT BETWEEN AREAS OF FORCING FOR PRECIP...WITH CURRENT PRECIPITATION HEADING FOR MICHIGAN AND THE FRONT FOR TUESDAY AFTERNOON REMAINING FAR ENOUGH NW TO KEEP THE AREA DRY. AT THE MOMENT...EXPECT MAINLY CLEAR SKIES TONIGHT...WITH LIGHT AND VARIABLE WINDS. WITH DEWPS UP IN THE UPPER 50S TO MID 60S...THIS COULD LEAD TO SOME POCKETS OF FOG DEVELOPING OVERNIGHT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 330 AM CDT MON AUG 5 2013 THE MAIN FORECAST CONCERN DURING THE TUESDAY THROUGH SUNDAY PERIOD WILL BE THE CHANCES FOR SHRA/TSRA TUESDAY AFTERNOON INTO TUESDAY NIGHT AS A COLD FRONT MOVES THROUGH THE REGION. THE REMAINS SOME VARIABILITY IN THE TIMING AND ORIENTATION OF THE FRONT AMONGST THE GFS... NAM... ECMWF... AND SREF... WITH THE NAM BEING FASTEST AND ECMWF BEING SLOWEST. A SHORTWAVE ROTATING EAST FROM THE NORTHERN ROCKIES WILL HELP DRIVE THE FRONT ACROSS THE AREA WHILE THE MAIN UPPER TROUGH DROPS SOUTH FROM CANADA. LARGE SCALE FORCING IN TERMS OF UPPER DIVERGENCE AND DPVA LOOK SUFFICIENT FOR FAIRLY WIDESPREAD PCPN TO OCCUR ALONG/AHEAD OF THE FRONT... WITH THALER QG DIAGNOSTICS DEPICTING AN ELONGATED AREA OF GOOD 700MB OMEGA FROM WESTERN LAKE SUPERIOR INTO NORTHWEST IOWA BY 00Z WEDNESDAY. THIS SHOULD BE MORE THAN SUFFICIENT TO GET SHRA/TSRA GOING DURING THE AFTERNOON HOURS AS THE FRONT MOVES THROUGH THE AREA. THE QUESTION THEN BECOMES WHETHER OR NOT ANY SEVERE WEATHER CAN BE EXPECTED. THE NEW DAY 2 OUTLOOK FROM SPC DOES INCLUDE A SLIGHT RISK ACROSS MOST OF THE AREA... ESSENTIALLY NEAR AND SOUTH OF I-94. IT LOOKS LIKE WE/LL HAVE ANYWHERE FROM 1000-2000 J/KG OF MLCAPE WITH WHICH TO WORK... ALONG WITH DEEP LAYER SHEAR AOA 40 KT... SO SOME ORGANIZED CONVECTION IS CERTAINLY POSSIBLE. DEEP LAYER SHEAR WILL BE SUFFICIENT FOR SUPERCELLS... BUT WOULDN/T EXPECT THE MODE TO REMAIN DISCRETE FOR VERY LONG GIVEN THE EXPECTATION FOR SOMEWHAT WIDESPREAD DEVELOPMENT. SO... CURRENT EXPECTATIONS WOULD BE FOR INITIAL SUPERCELLS TO QUICKLY TRANSITION INTO CLUSTERS AND A LINEAR SYSTEM WITH TIME. LOW LEVEL SHEAR DOESN/T LOOK TO BE TOO SIGNIFICANT... LIKELY AOB 15-20KT... WHICH SHOULD KEEP TORNADOES FROM BEING MUCH OF A THREAT... LEAVING LARGE HAIL AND WIND AS THE MAIN POTENTIAL ISSUES. THE FRONT SHOULD PUSH THROUGH THE REMAINDER OF THE FORECAST AREA TUESDAY NIGHT... WITH DRY WEATHER AND COOLER TEMPERATURES ON WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE AREA. THE NEXT CHANCE FOR PCPN LOOKS TO HOLD OFF UNTIL THURSDAY AFTERNOON AND THURSDAY NIGHT... WHEN THE MAIN UPPER LOW OVER CENTRAL CANADA DROPS SOUTH TOWARD THE INTERNATIONAL BORDER AND ANOTHER COLD FRONT PUSHES ACROSS THE REGION. MOISTURE RETURN WILL BE LIMITED AHEAD OF THE FRONT... BUT WILL BE SUFFICIENT GIVEN DECENT FORCING FOR SOME SHRA/TSRA. KEPT THINGS MAINLY DRY FROM FRIDAY THROUGH SUNDAY WITH THE EXPECTATION THAT AN EXPANSIVE HIGH WILL BUILD IN FROM CANADA. HOWEVER... IT SHOULD BE NOTED THAT THE 00Z ECMWF IS MORE PROGRESSIVE THAN THE GFS WITH THE UPPER PATTERN AND MANAGES TO FLATTEN THE FLOW OVER THE NORTH CENTRAL CONUS AND BRINGS A SURFACE LOW ACROSS MINNESOTA ON SUNDAY WITH DECENT FRONTOGENESIS AND AN ACCOMPANYING SLUG OF PCPN. STUCK CLOSER TO THE PREVIOUS FORECAST AND GFS AT THIS POINT... AND JUST INCLUDED SOME CHANCE POPS OVER THE SOUTHWEST PORTION OF THE CWFA ON SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1246 PM CDT MON AUG 5 2013 MVFR CIGS OVER MUCH OF THE REGION WITH ABUNDANT LOW LEVEL MOISTURE REMAINING IN THE WAKE OF THE OVERNIGHT/EARLY MORNING MCS. THIS SHOULD GRADUALLY LIFT THIS AFTERNOON...CLEARING OUT DURING THE EVENING. EXPECT CLOUDS TO LINGER LONGEST OVER THE NORTH AND EAST. SOME THREAT OF CONVECTION REFIRING INTO THE AFTERNOON ACROSS MAINLY WESTERN WI. THIS IS EXPECTED TO BE ISOLATED IT IT DOES REGENERATE...AND SHOULD WANE BY EARLY EVENING. WHERE CLOUD CLEAR OUT...SOME POSSIBILITY OF FOG FORMING LATE...MAINLY TO THE EAST AND SOUTH. WILL CONTINUE TO MENTION LIFR FOG AT KEAU AND SOME FOG AT KRNH. OTHER PROBLEM IS THE TIMING OF INCOMING COLD FRONT...WHICH WILL AFFECT KAXN REGION BEFORE 18Z...AND THEREAFTER ACROSS THE REST OF THE AREA. WILL MENTION VCSH THERE AFTER 15Z FOR NOW. SOUTH WINDS BECOMING NORTHWEST WITH TROUGH PASSAGE THIS AFTERNOON...AND BECOMING LIGHT/VRBL OVER MUCH OF THE AREA INTO TONIGHT. EXPECT WINDS TO BECOME SOUTHERLY AGAIN AHEAD OF THE COLD FRONT TUESDAY MORNING. KMSP...MVFR CIGS TO LIFT TO VFR THIS AFTERNOON...AND CLEARING INTO TONIGHT. EXPECT ANY CONVECTION THAT REDEVELOPS TO BE ISOLATED AND MAINLY EAST OF THE AREA...SO LEFT OUT OF TAF. SOME POSSIBILITY OF FOG FORMING IN THE RIVER VALLEYS LATER TONIGHT...WITH LIGHT WINDS AND LEFTOVER MOISTURE. DONT BELIEVE IT WILL BE WIDESPREAD ENOUGH TO INCLUDE IN THE TAF AT THE MOMENT. TIMING OF FRONT INTO TUESDAY AFTERNOON/EVENING IS THE OTHER PROBLEM. AFTER COLLABORATING WITH CWSU...DECIDED TO MENTION A PROB30 TSRA AFTER 21Z. WINDS WILL BE SOUTH TURING SOUTHWEST EARLY THIS AFTERNOON...THEN NORTHWEST LATE AFTERNOON INTO THE EVENING AS A WEAK TROUGH MOVES THROUGH. SHOULD SEE LIGHT WINDS OVERNIGHT AND SOUTHERLY AHEAD OF THE FRONT ON TUESDAY. /OUTLOOK FOR KMSP/ TUE...TSRA LIKELY AFTERNOON/EVENING. VFR OUTSIDE OF TSRA. WINDS WSW 5-10KTS...BCMG NW OVERNIGHT. WED...VFR. WINDS NW 10 KTS. THU...VFR. CHC TSRA OVERNIGHT. WINDS SW 5 KTS. && $$ SHORT TERM...MPG LONG TERM... AVIATION...DWE
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1256 PM CDT MON AUG 5 2013 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 335 AM CDT MON AUG 5 2013 THE LARGE SCALE FLOW REGIME HAS CHANGED LITTLE OVER THE LAST 24 HOURS WITH A VORTEX OVER HUDSON BAY AND UPPER HIGH CENTERED IN WEST TX AND NW FLOW ALOFT THROUGH THE NATIONS MIDSECTION. WEAK DISTURBANCES ALOFT CONTINUE TO TRACK FROM THE CENTRAL ROCKIES ESEWD THRU KS WITHIN THE FLOW ALOFT. CLUSTERS OF THUNDERSTORMS ACROSS SE KS AND SW MO EARLY THIS MORNING ARE OCCURING TO THE NORTH OF A QUASI- STATIONARY BOUNDARY DRAPPED FROM THE OK PANHANDLE INTO THE LOWER MS VALLEY AND IN ADVANCE OF ONE OF THESE WEAK DISTURBANCES...AND ARE STRONGLY DRIVEN BY A BROAD 30+ KT SWLY LLJ. MODEL CONSENSUS AND RECENT RUNS OF THE HRRR SUGGEST A FAMILIAR THEME TO RECENT MORNINGS...THE ACTIVITY WILL TRACK ESEWD THIS MORNING IN ADVANCE OF THE MIGRATING DISTURBANCE AND AS THE LLJ VEERS TO MORE WESTERLY. THIS SHOULD BRING THE GREATEST IMPACT OF THE WEAKENING SHOWERS AND THUNDERSTORMS TO THE EASTERN OZARKS THIS MORNING...WITH ANY RESIDUAL SHOWERS EXITING BY EARLY AFTERNOON. FORCING FOR ANY PRECIPITATION IS RATHER WEAK AND NON-FOCUSED ELSEWHERE AND WORTHY OF A MERE SLIGHT CHANCE. I THINK THERE WILL BE A SLIGHT NORTHWARD JOG IN THE MCS TRACK TONIGHT INTO TUESDAY AS THE BOUNDARY TO THE SOUTH LIFTS SLIGHTLY AND DISTURBANCES ALOFT TRACK A TAD FURTHER NORTH THAN THE LAST SEVERAL DAYS. PRESENT INDICATIONS ARE THAT THE ONE OR MORE MCSS WILL DEVELOP FROM SOUTH CENTRAL KS INTO SOUTH CENTRAL MO AS THE SWLY LLJ RAMPS UP THIS EVENING AND THEN STRENGTHENS AND VEERS OVERNIGHT. THIS ACTIVITY WILL BE ONGOING WITHIN THIS CORRIDOR AT DAYBREAK TUESDAY AND SHIFTING TO THE ESE DURING THE DAY IN ADVANCE OF THE MIGRATING DISTURBANCE ALOFT AND AS THE LLJ CONTINUES TO VEER. THE HIGHEST POPS WILL BE CONCENTRATED ALONG AN AXIS JEFFERSON CITY TO FARMINGTON. GLASS .LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY) ISSUED AT 335 AM CDT MON AUG 5 2013 CONSENSUS OF THE ECMWF...SREF...AND NAM IS WE SHOULD SEE A SYNOPTIC SCALE COLD FRONT PUSH INTO NRN SECTIONS OF THE AREA LATE TUESDAY NIGHT AND PROGRESS SEWD DURING THE DAY ON WEDNESDAY. A BROAD SWLY LLJ OF 30+ KTS REMAINS FOCUSED AHEAD OF THE FRONT TUESDAY NIGHT AND SHOULD SUPPORT LIKELY PROBABILITIES OF SHOWERS AND THUNDERSTORMS WITH THAT THREAT SHIFTING SEWD AHEAD OF THE FRONT ON WEDNESDAY. THE UPPER FLOW REGIME WILL CHANGE SLIGHTLY WEDNESDAY THROUGH FRIDAY WITH A MORE ZONAL COMPONENT WHILE THE FRONT BECOMES QUASI-STATIONARY FROM THE TN VALLEY ACROSS ARKANSAS INTO NORTHERN OK. THIS MORE ZONAL COMPONENT IN THE FLOW ALOFT WILL BRING THE DISTURBANCE TRACK WEST TO EAST MORE THROUGH THE MID MS VALLEY AND MODULATE THE S/SWLY LLJ...TO BRING A CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS TO THE SOUTHERN 2/3RDS OF THE CWA AT LEAST INTO FRIDAY. GLASS && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1241 PM CDT MON AUG 5 2013 RIDGE OF SFC HIGH PRESSURE CONTINUE TO SLIDE OFF TO THE EAST WITH WINDS NOW OUT OF THE SOUTH NEAR 10 KTS. RAIN ASSOCIATED WITH OVERNIGHT MCS HAS LARGELY STAYED SOUTH OF TAF SITES. HOWEVER...SOME MVFR CEILINGS ARE POSSIBLE THROUGH MID AFTERNOON TO THE NORTH OF THIS FEATURE. CEILINGS WILL ALSO BE THE PRIMARY CONCERN TONIGHT. FRONT OVER THE MID SOUTH WILL RETREAT NORTHWARD TONIGHT AS A WARM FRONT WITH WINDS BACKING MORE TO THE SOUTHEAST AROUND 5 KNOTS. LOW CEILINGS ARE LIKELY WITH FOG POSSIBLE AHEAD OF THE FRONT AND AM FORECASTING MVFR CEILINGS...THOUGH MODELS INDICATE THEY COULD DIP DOWN INTO IFR. WARM FRONT WILL PASS THROUGH THE AREA BY AROUND NOON WITH AREAS TO THE SOUTH OF THE BOUNDARY HAVING WINDS VEER TO THE SOUTH SOUTHWEST. SPECIFICS FOR KSTL... RIDGE OF SFC HIGH PRESSURE CONTINUE TO SLIDE OFF TO THE EAST WITH WINDS NOW OUT OF THE SOUTH NEAR 10 KTS. RAIN ASSOCIATED WITH OVERNIGHT MCS HAS LARGELY STAYED SOUTH OF LAMBERT FIELD. HOWEVER...SOME MVFR CEILINGS ARE POSSIBLE THROUGH MID AFTERNOON TO THE NORTH OF THIS FEATURE. LEFT OUT OF TAF FOR NOW AS 975 TO 900 HPA MEAN FLOW HAS VEERED TO THE WEST NORTHWEST AND SHOULD KEEP THESE AFOREMENTIONED CEILINGS JUST TO THE SOUTH OF THE TERMINAL. HOWEVER...WILL MONITOR AND AMEND AS NECESSARY THIS AFTERNOON. CEILINGS WILL ALSO BE THE PRIMARY CONCERN TONIGHT. FRONT OVER THE MID SOUTH WILL RETREAT NORTHWARD TONIGHT AS A WARM FRONT WITH WINDS BACKING MORE TO THE SOUTHEAST AROUND 5 KNOTS. LOW CEILINGS ARE LIKELY WITH FOG POSSIBLE AHEAD OF THE FRONT AND AM FORECASTING MVFR CEILINGS...THOUGH MODELS INDICATE THEY COULD DIP DOWN INTO IFR. WARM FRONT WILL PASS THROUGH THE AREA BY AROUND NOON WITH AREAS TO THE SOUTH OF THE BOUNDARY HAVING WINDS VEER TO THE SOUTH SOUTHWEST. THE ATMOSPHERE WILL ALSO BECOME INCREASINGLY UNSTABLE SO INTRODUCED A VCSH GROUP BEGINNING AT 1900 UTC. GOSSELIN && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1131 AM CDT MON AUG 5 2013 .AVIATION... 18Z TAFS FOR KOFK...KOMA AND KLNK. ALTHOUGH MORNING CONVECTION WAS SHOWING APPARENT SIGNS OF WEAKENING IT COULD STILL IMPACT TAF SITES. WITH 18Z FORECAST IT APPEARED KOMA WAS AIRPORT POTENTIALLY IMPACTED AND A BRIEF TSTM TEMPO GROUP WAS FORECAST. HOWEVER...TRENDS WILL NEED MONITORING AS WEAK BOUNDARY IN REGION AND AFTERNOON HEATING COULD INCREASE COVERAGE AGAIN. OTHERWISE...A GENERAL DECREASE IN MVFR CIGS EXPECTED THROUGH AFTERNOON...WITH VFR CIGS OR NO CIGS BY LATE AFTERNOON. LATER TONIGHT IFR CIGS COULD AGAIN DEVELOP AHEAD OF ANOTHER TSTM COMPLEX PROBABLY MOVING TOWARD ERN NEBR BY TUESDAY MORNING. THIS IFR CIG MENTION WAS MAINTAINED AT KOFK/KLNK WITH TEMPO LOW MVFR CIG FORECAST AT KOMA AT THIS TIME. A PROB30 GROUP WAS CARRIED AT KOFK WHERE TSTM ACTIVITY APPEARED MOST POSSIBLE TUESDAY MORNING. CHERMOK && .PREV DISCUSSION... /ISSUED 352 AM CDT MON AUG 5 2013/ DISCUSSION... SHORT TERM CONCERNS WILL BE LOW CLOUDS AND FOG THIS MORNING AND POTENTIAL FOR ISOLATED SHOWERS AND THUNDERSTORMS TODAY IN THE NORTH THEN ATTENTION TURNS TO TUESDAY CONVECTIVE POTENTIAL. WATER VAPOR SATELLITE IMAGERY AND LIGHTNING DATA SHOW MOISTURE STREAMING NORTHWARD ACROSS MEXICO INTO THE FOUR CORNERS REGION INTO THE PLAINS AND THEN SOUTHEAST TOWARD THE LOWER MISSISSIPPI VALLEY... ANTI-CYCLONICALLY AROUND THE LARGE AREA OF H5 HIGH PRESSURE CENTERED OVER NEW MEXICO AND WEST TEXAS. MEANWHILE...CONVECTION WAS ALSO MOVING INTO THE PACIFIC NORTHWEST AND ACROSS THE NORTHERN PLAINS...WHERE THE STRONGER H3 JET RESIDED. THERE WERE 10 TO 20 METER HEIGHT FALLS ASSOCIATED WITH SHORTWAVE TROFS OVER NORTH DAKOTA AND ALSO NEAR SPRINGFIELD MISSOURI. THERE WAS ABUNDANT MOISTURE OVER THE PLAINS WITH MOST LOCATION ON THE PWAT CHART BETWEEN 100-160% OF NORMAL. WIDESPREAD H85 DEWPOINTS OF +12 TO +16C...WITH A MAX OF +18C AT DDC. H7 DEWPOINTS WERE +9 DEG C AT DDC AND +6 AT TOP. H7 TEMPERATURES HAD WARMED INTO THE +10 TO +14 C RANGE FOR MUCH OF THE PLAINS...WITH THE COOLER TEMPS TOWARD ABR...TOP/SPRINGFIELD. THERE WERE TWO THERMAL RIDGES AT H85...ONE WAS NOSING INTO THE NEBRASKA PANHANDLE AND THE OTHER WAS NOSING INTO THE TEXAS PANHANDLE AND OKLAHOMA. THE LATEST WSR-88D RADAR MOSAIC SHOWED THREE CONVECTIVE COMPLEXES....ONE ACROSS MN/NRN IA...ONE OVER SOUTHEAST KANSAS AND ONE OVER WESTERN SOUTH DAKOTA. AFTER SOME MORNING CLOUDS AND FOG...A STRONG SHORTWAVE TROF OVER NORTH DAKOTA WILL CONTINUE TO PUSH SOUTHEAST TODAY AND WILL DRAG A FRONT INTO NORTHEAST NEBRASKA. THE BULK OF THE CONVECTIVE ACTIVITY SHOULD REMAIN TO OUR NORTH AND EAST...LIMITED BY THE WARM MID LEVEL TEMPERATURES LOCALLY...HOWEVER ISOLATED ELEVATED THUNDERSTORMS COULD MAKE IT INTO NORTHEAST NEBRASKA AND WEST CENTRAL IOWA. THERE IS STRONG DEEP LAYER SHEAR OF 50KTS...SO STORMS WILL NEED TO BE WATCHED NEAR THE SD/NEB BORDER. MOST OF THE SHORT RANGE MODELS LIMIT THE SOUTHWARD PROGRESS DURING THE DAY...HOWEVER THE LATEST RAP IS MORE AGGRESSIVE WITH PRECIPITATION MAKING IT FARTHER SOUTH...SO THIS WILL NEED TO BE WATCHED. WARMER H85 TEMPS ARE EXPECTED AND HAVE HIGHS IN THE 80S ALTHOUGH IF CLOUDS HANG ON...THIS COULD KEEP THE HIGHS A LITTLE LOWER. MONDAY NIGHT...AN MCS IS FORECAST TO DEVELOP OVER THE NORTHERN PLAINS AND SPREAD SOUTHEAST. THIS SYSTEM HAS DECENT INSTABILITY OF 3-4000J/KG AND DEEP LAYER SHEAR OF 45-53KTS THUS STORMS COULD BE SEVERE. THE MODELS HAVE A VARIETY OF SOLUTIONS ON THE PLACEMENT OF THE BEST PRECIP...HOWEVER WILL MAINTAIN HIGH POPS WITH THE FRONT TUESDAY INTO TUESDAY EVENING. POOLING OF MOISTURE ALONG THE FRONT COULD RESULT IN LOCALLY HEAVY RAINS. DRYING ENSUES WITH SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTH SHOULD SHUT DOWN THE PRECIPITATION TUESDAY NIGHT AND WEDNESDAY. HIGHS WEDNESDAY SHOULD BE COOLER...IN THE 70S TO LOWER 80S. RETURN FLOW SETS UP WEDNESDAY NIGHT AND COULD SEE SOME STORMS RETURN ESPECIALLY SOUTHWEST. THE EXTENDED THURSDAY THROUGH SUNDAY. H5 LOW PRESSURE OVER HUDSON BAY WILL SLOWLY MOVE EAST WITH BUILDING HEIGHTS OVER THE ROCKIES AND NORTHWEST FLOW ALOFT FOR THE FORECAST AREA. DEEP MOISTURE WILL REMAIN IN PLACE...ESPECIALLY FOR THE SOUTHERN PART OF THE FORECAST AREA AND THIS IS WHERE THERE WOULD BE A HIGHER RISK OF THUNDERSTORMS. SHORTWAVES IN THE NORTHWEST FLOW ALOFT AND STORMS THAT FORM IN THE WESTERN HIGH PLAINS COULD ROLL EAST FRIDAY NIGHT INTO SUNDAY NIGHT...ALTHOUGH THE EASTERLY LOW LEVEL FLOW OFF THE SURFACE HIGH COULD LIMIT COVERAGE. THERE ARE DECENT MODEL DIFFERENCES BY SUNDAY AS TO WHERE THE FRONTAL SYSTEMS WILL BE THUS HAVE LEFT IN THE CHC POPS. HIGHS WILL CONTINUE TO BE AT OR BELOW NORMAL. ZAPOTOCNY && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
244 PM MDT MON AUG 5 2013 .DISCUSSION... LESS ACTIVE TODAY THAN AT THIS TIME YESTERDAY. SHOWERS AND STORMS WITH LOCALLY HVY RAIN ARE STILL DEVELOPING OVER THE NORTHERN AND WESTERN HIGH TERRAIN AND EASTERN HIGH PLAINS. STORM MOTIONS ARE FASTER AND MORE TO THE NORTHEAST. LAPS PARAMETERS STILL INDICATE POTENTIAL FOR A FEW STRONG STORMS ARE FLASH FLOODING IS NOT OUT OF THE QUESTION FOR ANY AREA. RUC GUIDANCE AGAIN SHOWS ACTIVITY MERGING INTO THE RGV THIS VALLEY HOWEVER CONFIDENCE NOT AS HIGH SINCE OTHER GUIDANCE MEMBERS KEEP ALL ACTIVITY FARTHER SOUTH AND THERE IS A LESS THAN IMPRESSIVE CU FIELD OVER THE AREA ATTM. THE INTERESTINGLY THERE IS A WELL DEFINED WAVE THAT HAS DEVELOPED IN THE MONSOONAL PLUME HEADING NORTH INTO THE NM BOOTHEEL. FOR THIS REASON HAVE KEPT A LARGER THAN TYPICAL AREA OF CHANCE POPS FOR THE OVERNIGHT. THE NEXT VERY WELL DEFINED WAVE IS POISED OVER THE BAJA REGION AND THIS WILL MOVE NORTH THROUGH THE MONSOON PLUME TUESDAY. TOTAL BLENDED PWAT VALUES PER CIRA IMAGERY WITH THIS WAVE ARE IN THE 2.25-2.50 RANGE. 12Z GFS INDICATES THE MAX THETA-E WAVE ASSOCIATED WITH THIS SYSTEM WILL SLIDE OVER CENTRAL AND WESTERN NM NOW... WHICH IS A LITTLE FARTHER EAST THAN PREVIOUS RUNS. STORM MOTIONS WILL BE FASTER TO THE NE BUT FLASH FLOODING IS STILL A CONCERN. THIS UPPER WAVE WILL GET CAUGHT UP IN INCREASING WESTERLY FLOW OVER THE CENTRAL ROCKIES THEN NW FLOW OVER THE GREAT PLAINS. A BACK DOOR FRONTAL BOUNDARY WILL BE FORCED SOUTHWARD INTO THE NE PLAINS BEHIND THESE UPPER DYNAMICS. VERY MOIST UPSLOPE FLOW WILL IMPACT THE SANGRES EASTWARD ACROSS THE PLAINS AND GIVEN LATEST ROUNDS OF HEAVY RAINFALL IN THIS AREA...THE FLASH FLOOD THREAT WILL BE QUITE HIGH. WEDNESDAY NIGHT EXPECTING TO SEE A LARGE RAIN SHIELD SHIFTING SOUTHEAST OVER THE EAST...FOLLOWED BY A DRIER DAY FOR THURSDAY. TEMPS WILL BE BELOW NORMAL THROUGH THE WHOLE PERIOD. THE FRIDAY THROUGH MONDAY PERIOD LOOKS INTERESTING WITH ANOTHER MONSOON BURST POSSIBLE DURING THIS TIME OVER CENTRAL AND WESTERN NM. MODEL CONSISTENCY ON TIMING AND PLACEMENT IS NOT THE BEST SO WILL KEEP VALUES JUST AT CLIMO OR BELOW FOR NOW. GUYER && .FIRE WEATHER... UPPER HIGH WILL REMAIN CENTERED OVER PORTIONS OF TEXAS AND THE LOWER MISSISSIPPI VALLEY THROUGH TUESDAY. THE MONSOONAL MOISTURE PLUME WILL REMAIN CENTERED OVER WESTERN AND CENTRAL NEW MEXICO DURING THIS PERIOD. WETTING THUNDERSTORMS WILL BE EMBEDDED WITHIN THIS PLUME WITH HIGHER HUMIDITY. MODELS SHOWS A GRADUAL CHANGE IN THE MONSOON FLOW WEDNESDAY AND THURSDAY AS A WEAK TROUGH SWINGS ACROSS THE SOUTHERN AND CENTRAL ROCKIES. WEDNESDAY COULD BE QUITE DYNAMIC AS FAR AS AN EXPECTED DRIER TREND ACROSS THE WEST AND WETTING THUNDERSTORMS CENTRAL AND EASTERN AREAS. MODELS SHOW AN UPTICK IN THE UPPER FLOW SO THIS SHOULD TRANSLATE INTO A LITTLE STRONGER SURFACE WIND VERSUS WHAT WE HAVE HAD THE PAST SEVERAL DAYS. MIGHT BE A LITTLE LOW IN THE GRIDDED WIND FORECAST SO WILL WATCH THE TREND IN THE MODELS. A BACK DOOR COLD FRONT TIED TO A VIGOROUS LOW PRESSURE AREA SHOULD ADD TO THE THUNDERSTORM FOCUS ACROSS THE NORTHEAST. IT APPEARS THAT HUMIDITY VALUES LOWER THE MOST ACROSS THE SOUTHWEST HALF. THURSDAY LOOKS TO BE DRIER BOTH HUMIDITY AND WETTING THUNDERSTORM WISE. WINDS ALSO LOOK TO BE LIGHTER ON THURSDAY VERSUS WEDNESDAY. BOTH THE ECMWF AND GFS WEATHER MODELS SHOW THE UPPER HIGH REDEVELOPING OVER CENTRAL TEXAS ON FRIDAY. MONSOONAL MOISTURE WOULD TRY TO FLOW BACK OVER THE AREA. AS OF RIGHT NOW...RESIDUAL OR LEFTOVER MOISTURE SHOULD FOCUS WETTING THUNDERSTORM DEVELOPMENT OVER THE NORTH CENTRAL MOUNTAINS AND PORTIONS OF THE NORTHEAST PLAINS. THE PLUME OF MOISTURE SHOULD REINVIGORATE OVER WESTERN AND CENTRAL NEW MEXICO DURING THE WEEKEND. HUMIDITY VALUES WOULD TREND UP. A MONSOON BURST CONCENTRATING SIGNIFICANT MOISTURE AND STORMS WOULD BE POSSIBLE DURING THIS PERIOD. WEATHER MODELS TRY TO ELONGATE THE UPPER HIGH OVER PORTIONS OF NEW MEXICO EARLY NEXT WEEK. RESIDUAL MOISTURE WOULD BE AROUND AND CAUGHT WITHIN THIS UPPER HIGH ALTHOUGH STORMS WOULD BE MORE IN THE RECYCLE MODE VERSUS A TRUE MONSOON BURST MODE. THUS THE WETTING RAIN COVERAGE WOULD GRADUALLY DECLINE. WILL CONTINUE TO MONITOR THIS TREND. 50 && .AVIATION... 18Z TAF CYCLE BASED ON STEERING FLOW CONSIDERATIONS AND THE LATEST MODEL FORECASTS DECIDED TO GO BULLISH FOR WESTERN TERMINAL SITES LIKE GUP. DO NOT HAVE MVFR CIGS ASSOCIATED WITH THE STORMS ALTHOUGH COULD SEE SOME MTN TOP OBSCD FOR A PERIOD. MAIN CONVECTIVE ACTION SHOULD BE OUT WEST TODAY. STORMS SHOULD ALSO FIRE UP ALONG THE EAST SLOPES OF THE CENTRAL MTNS BUT THE ATMOSPHERE MAY BE A BIT WORKED OVER FROM YESTERDAY/S CONVECTION. EITHER WAY...GOING WITH SOME VCSH AT ABQ/SAF AND LVS LATER IN THE DAY. TCC AND ROW SHOULD BE UNDER VFR CONDITIONS THE NEXT 24 HOURS. 50 && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 65 88 64 87 / 20 20 20 20 DULCE........................... 54 83 54 79 / 30 40 40 40 CUBA............................ 55 83 54 81 / 50 50 40 40 GALLUP.......................... 58 82 58 83 / 30 30 30 20 EL MORRO........................ 53 76 51 78 / 40 50 40 30 GRANTS.......................... 57 80 57 82 / 40 40 40 20 QUEMADO......................... 56 79 53 81 / 40 50 50 20 GLENWOOD........................ 60 84 59 86 / 30 30 30 20 CHAMA........................... 51 75 51 70 / 50 50 40 60 LOS ALAMOS...................... 60 82 58 79 / 50 40 30 50 PECOS........................... 59 79 57 75 / 40 40 40 40 CERRO/QUESTA.................... 54 79 55 75 / 40 40 40 50 RED RIVER....................... 48 71 48 67 / 50 60 60 60 ANGEL FIRE...................... 46 75 47 70 / 50 60 50 60 TAOS............................ 54 84 54 78 / 40 40 40 50 MORA............................ 54 78 55 73 / 40 50 40 60 ESPANOLA........................ 62 86 61 83 / 40 30 30 40 SANTA FE........................ 60 81 58 78 / 40 30 30 40 SANTA FE AIRPORT................ 62 86 60 84 / 40 30 30 40 ALBUQUERQUE FOOTHILLS........... 68 84 65 86 / 40 30 30 20 ALBUQUERQUE HEIGHTS............. 69 86 67 88 / 30 30 30 20 ALBUQUERQUE VALLEY.............. 65 89 66 89 / 30 30 30 20 ALBUQUERQUE WEST MESA........... 67 89 65 90 / 40 30 30 20 LOS LUNAS....................... 66 88 65 88 / 30 30 30 20 RIO RANCHO...................... 66 89 65 90 / 40 30 30 20 SOCORRO......................... 67 92 66 92 / 30 30 30 10 SANDIA PARK/CEDAR CREST......... 61 82 59 83 / 40 30 30 30 TIJERAS......................... 62 84 59 84 / 40 30 30 30 MORIARTY/ESTANCIA............... 59 84 59 84 / 40 30 30 30 CLINES CORNERS.................. 60 81 59 80 / 30 30 40 30 GRAN QUIVIRA.................... 62 84 59 82 / 40 30 40 20 CARRIZOZO....................... 65 88 64 86 / 30 30 30 10 RUIDOSO......................... 58 80 57 78 / 30 50 40 20 CAPULIN......................... 57 83 57 75 / 50 50 50 60 RATON........................... 59 88 59 79 / 50 50 40 60 SPRINGER........................ 59 88 60 81 / 40 40 30 60 LAS VEGAS....................... 58 83 58 78 / 30 50 40 50 CLAYTON......................... 67 93 66 84 / 40 20 40 60 ROY............................. 63 89 63 82 / 40 30 30 50 CONCHAS......................... 70 95 69 90 / 30 20 20 30 SANTA ROSA...................... 69 93 68 90 / 20 20 20 20 TUCUMCARI....................... 72 99 71 94 / 20 10 20 30 CLOVIS.......................... 69 97 69 93 / 10 10 10 10 PORTALES........................ 69 98 70 94 / 5 10 10 10 FORT SUMNER..................... 71 95 70 92 / 10 20 20 20 ROSWELL......................... 72 98 72 97 / 5 10 10 10 PICACHO......................... 65 89 64 89 / 10 20 20 10 ELK............................. 62 82 61 83 / 30 40 30 30 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
222 PM EDT MON AUG 5 2013 .SYNOPSIS... HIGH PRESSURE OVER NEW YORK WILL MOVE OFF THE EAST COAST TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP ON TUESDAY AND CONTINUE INTO WEDNESDAY AHEAD OF A COLD FRONT. SCATTERED SHOWERS WILL BE POSSIBLE ON TUESDAY OVER PORTIONS OF NORTHEAST PENNSYLVANIA AND CENTRAL NEW YORK...WITH SHOWERS AND THUNDERSTORMS BECOMING MORE LIKELY ON WEDNESDAY AND WEDNESDAY NIGHT AS THE COLD FRONT APPROACHES. LINGERING SHOWERS WILL BE POSSIBLE ACROSS NORTHEAST PENNSYLVANIA INTO THURSDAY AFTERNOON NEAR THE DEPARTING FRONT. && .NEAR TERM /THROUGH TUESDAY/... SFC HI PRES CNTRD OVER NY/PA THIS AFTN WILL DRIFT EWD OFF THE EAST CST TNGT. DIURNAL CU XPCTD TO DSPT LATER THIS AFTN...WITH SOME MID AND HI LVL CLDS WORKING INTO THE RGN TNGT. RUC LOOKS OVERDONE WITH RETURNING LOW LVL MSTR LATER TNGT...AND XPCT ANY CONVECTION ASSCD WITH UPSTREAM S/WV`S OVER THE GTLAKES TO DSPT/WEAKEN AS THEY MOV EWD TWDS THE RGN. K INDICES ON TUE AFTN SUGGEST BEST CHC FOR SCT CONVECTION ACRS PORTIONS OF THE WYOMING VLY INTO THE CNTRL SRN TIER AND FINGER LAKES WHERE K`S >32 AND BL LI`S ARND -1 TO -2. GFS ALSO SUGGESTS BEST CHC FOR SCT ACTIVITY WILL BE ACRS WRN ZONES ON TUE BASED ON LOW LVL CONVERGENCE AND INSTABILTY FIELDS. FOR NOW JUST INDICATED THE CHC FOR -SHRA ON TUE ACRS THESE AREAS. CLD FIELDS AVERAGED OUT TO MOSTLY CLDY...BUT WE`LL LIKELY SEE A DECENT AMT OF SUNSHINE THROUGH THE MID/UPR DECK. MAXES GNRLY M/U70S. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... CONFIDENCE FACTOR DECREASES IN THE SHORT TERM...AS DETERMINISTIC MDLS STILL SHOW DIFFS IN TIMING OF FNT AND POTNL CONVECTIVE SYSTEMS. LOW LVL MSTR WILL INCRS ON SRLY FLOW...WITH LOW CLDS PSBL ACRS THE SRN TIER AND NE PA BY WED MRNG. FOR NOW RETAINED SLGT CHC/LOW CHC POPS ON TUE NGT...INCRSNG TO LIKELY BY WED NGT WITH APRCH OF THE CDFNT. BY 12Z THU...IT APPEARS THAT THE FNT WILL JUST BE ENTERING THE FAR WRN/NW ZONES...GETTING INTO THE SRN CATSKILLS AND NE PA BY THU EVNG. SOME IMPRVMNT IS LIKELY IN THE AFTN ACRS THE FINGER LAKES...CNTRL SRN TIER AND SRN TUG ON THU AFTN...WITH CHC POPS ACRS SE ZONES CLOSER TO THE FNT. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... CHGS MADE TO EXTNDD PORTION OF THE FCST BASED ON 12Z GUIDANCE FILTERING IN. 12Z GFS BRINGS BNDRY THRU THURSDAY AND THEN IT APPEARS TO GET HUNG UP ACRS THE AREA. THIS WL SET THE STAGE FOR SFC LOW TO RIDE UP ALONG THE FRONT PER GFS AND LATEST CMC ON FRIDAY. GFS IS FURTHER NORTH THAN CMC AT THIS POINT RIDING IT NORTH ALONG THE AXIS OF THE GREAT LKS, WHEREAS CMC MVS IT ACRS NRN TIER OF PA INTO HUDSON VLY BY 06Z SATURDAY. 00Z EURO ALSO HINTING AT A WK LOW TREKKING ACRS THE AREA ON FRIDAY THO NOT AS STRONG AS GFS OR CMC. BASED ON LATEST TRENDS, HV BUMPED POPS TO BTWN 40-50% FOR FRIDAY AND DROPPED AFTN MAXES INTO THE 70S. FROPA LOOKS TO FINALLY OCCUR FRIDAY NIGHT AS SFC LOW HEADS INTO CANADIAN MARITIMES WITH DRYING HIPRES BUILDING IN AND POPS DWINDLING BY 12Z SATURDAY. NW FLOW WL FILTER IN COOL ADVECTION WITH H8 TEMPS DROPPING TO NR +10C FOR SATURDAY AFTN. CAA CONTS FOR SUNDAY AS NW FLOW RMNS OVR THE AREA THUS EXPECTING TEMPS TO BE COOLER ON SUNDAY WITH OVERALL TEMPS THRU THE PD RUNNING BLO NORMAL. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... 18Z UPDATE... HIGH PRESSURE BUILDING INTO THE AREA THIS AFTERNOON WILL RESULT IN SCT-BKN CUMULUS FIELD DIMINISHING AFTER 00Z AND LEAVING HIGH CIRRUS IN ITS WAKE. VFR CONDITIONS EXPECTED NEXT 24 HOURS UNDER HIGH PRESSURE. DRY AIRMASS WILL PREVENT MUCH IN THE THE WAY OF FOG DEVELOPING TONIGHT. WINDS LIGHT OUT OF THE NORTHWEST EARLY WILL BECOME MORE SOUTHEASTERLY TONIGHT THEN INCREASE IN SPEEDS AFTER 14Z TUESDAY. OUTLOOK... TUE AFTERNOON/TUE NIGHT...CHC MVFR SHWRS AFTER 18Z. WED/WED NIGHT...MVFR CIGS SHWRS/TSRA. THU...MVFR IN SHRA AND TSRA IMPROVING TO VFR LATE. FRI...MVFR IN SHRA/TSRA. SAT...BECOMING VFR UNDER HIGH PRESSURE && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ LONG TERM...PVN AVIATION...PVN
AREA FORECAST DISCUSSION
NWS RALEIGH NC
318 PM EDT MON AUG 5 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OVER THE MID ATLANTIC WILL MOVE OFFSHORE TONIGHT. A MOIST SOUTHERLY LOW LEVEL RETURN FLOW WILL PREVAIL THROUGH MID TO LATE WEEK. && .NEAR TERM /THROUGH TUESDAY/... AS OF 300 PM MONDAY... OVERVIEW: SYNOPTIC SUBSIDENCE /HEIGHT RISES/ OVER THE MID-ATLANTIC THIS MORNING WILL WANE AND SHIFT TO NEW ENGLAND THIS AFT/TONIGHT AS AN UPPER LEVEL TROUGH PROGRESSES FURTHER NORTHEAST INTO THE CANADIAN MARITIMES. ACCORDINGLY...1021 MB SFC HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC THIS MORNING WILL WEAKEN AND SHIFT OFFSHORE THE MID- ATLANTIC COAST. AS THE SFC HIGH PROGRESSES EASTWARD AND A LIGHT S/SE RETURN FLOW DEVELOPS OVER THE WESTERN CAROLINAS THIS AFT/EVE...A STATIONARY FRONT EXTENDING EASTWARD FROM NORTHERN GA INTO CENTRAL/UPSTATE SC WILL BEGIN TO LIFT NORTH FROM UPSTATE SC INTO WESTERN NC (ALONG AND WEST OF I-77)...WITH MOISTURE SLOWLY INCREASING TONIGHT ALONG AND WEST OF THE HIGHWAY 1 CORRIDOR. TONIGHT: GIVEN THE AFOREMENTIONED MOISTURE IN ADDITION TO SEASONABLY WEAK MID-LEVEL LAPSE RATES...DIURNAL DESTABILIZATION TODAY WILL BE MARGINAL AND LARGELY CONFINED TO WESTERN PORTIONS OF THE STATE WHERE LOW-LEVEL CONVERGENCE /MOISTURE POOLING/ AND THE SLOW NORTHWARD RETREAT OF THE FRONT WILL CONTRIBUTE TO PERHAPS 250-500 J/KG MLCAPE. GRADUAL LOW-LEVEL MOISTURE RETURN OVERNIGHT WILL RESULT IN A SLOW INCREASE IN MUCAPE...PERHAPS UP TO 500 J/KG IN THE WESTERN PIEDMONT AND 1000 J/KG IN THE FOOTHILLS/MOUNTAINS BY 12Z TUE MORNING. FORCING FOR ASCENT WILL BE CONFINED TO WEAK/SHALLOW LOW-LEVEL CONVERGENCE AND UPSLOPE FLOW IN WESTERN NC THIS AFTERNOON INTO TONIGHT. ALTHOUGH THERE IS AT LEAST A POTENTIAL FOR SMALL AMPLITUDE DISTURBANCES IN W/NW FLOW ALOFT THROUGH TONIGHT...19Z WV IMAGERY AND RAP DATA DO NOT SUGGEST ANY SIGNIFICANT DPVA WILL BE PRESENT. PER 19Z VIS SAT/RADAR IMAGERY INDICATING SHALLOW AGITATED CU AND A FEW BRIEF SHOWERS IN THE WEST...WILL INDICATE A SLIGHT CHANCE OF SHOWERS THROUGH THIS EVENING. INCREASINGLY MOIST LOW-LEVEL UPSLOPE FLOW AND A RELATIVELY BETTER CHANCE FOR SMALL AMPLITUDE DISTURBANCES ALOFT SHOULD RESULT IN A BETTER CHANCE FOR ISOLD/SCT SHOWERS IN THE WESTERN PIEDMONT PRIOR TO SUNRISE TUE...SUPPORTED BY THE LATEST HIGH-RES CONVECTION ALLOWING MODELS. WILL INDICATE INCREASING PRECIP CHANCES. EXPECT LOWS TONIGHT NEAR OR SLIGHTLY BELOW NORMAL...IN THE LOWER TO UPPER 60S...WARMEST IN THE WEST/SW PIEDMONT WHERE MORE CLOUD COVER AND BETTER LOW-LEVEL MOISTURE WILL BE PRESENT AND COOLEST IN THE TYPICAL AREAS OF THE NORTHERN PIEDMONT AND NE COASTAL PLAIN WHERE A DRIER AIRMASS AND LESS CLOUD COVER (AT LEAST INITIALLY) WILL PREVAIL. TUESDAY: EXPECT AN INCREASING POTENTIAL FOR SHOWER (THUNDERSTORM) ACTIVITY TUESDAY MORNING (AFTERNOON) AS A SEASONABLY MOIST SOUTHERLY LOW-LEVEL RETURN FLOW AIDS IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION IN THE PRESENCE OF WEAK LOW-LEVEL CONVERGENCE AND AN INCREASED POTENTIAL FOR SMALL AMPLITUDE DISTURBANCES IN NW FLOW ALOFT. WILL INDICATE PRECIP CHANCES RANGING FROM 20-50%...HIGHEST IN THE WESTERN PIEDMONT AND LOWEST IN THE COASTAL PLAIN WHERE LOW-LEVEL MOISTURE /DIURNAL DESTABILIZATION/ IS EXPECTED TO BE MARGINAL. HIGHS WILL BE SIMILAR TO TODAY AND PRIMARILY DEPEND ON CLOUD COVER... RANGING FROM NEAR 80F IN THE N/NW PIEDMONT TO MID/UPPER 80S IN THE SANDHILLS AND COASTAL PLAIN. -VINCENT && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 318 PM MONDAY... TUESDAY NIGHT...APPROACH OF A WEAK MID-UPPER LEVEL DISTURBANCE COUPLED WITH AN INCREASINGLY MOIST AIR MASS WILL SUPPORT THE POTENTIAL FOR A FEW SHOWERS/ISOLATED THUNDER WELL INTO THE NIGHT...MAINLY OVER THE NW PIEDMONT. INCREASING/THICKENING CLOUD COVER AND A LIGHT SLY WIND WILL RESULT IN A FAIRLY UNIFORM TEMP FIELD OVERNIGHT. MIN TEMPS UPPER 60S TO AROUND 70. WEDNESDAY AND WEDNESDAY NIGHT...THE MID-UPPER LEVEL TROUGH TRANSLATE SLOWLY EWD TOWARD AND ACROSS THE MID ATLANTIC AND CAROLINAS WED AFTERNOON-EVENING. 12Z GFS NOT TOO IMPRESSIVE WITH ITS CONVECTIVE PARAMETERS WED AFTERNOON-EVENING ...DEPICTING MARGINAL/SLIGHT INSTABILITY AT BEST. STILL...FAVORED LOW LEVEL CONFLUENCE OVER THE WESTERN PIEDMONT DURING PRIME HEATING SUPPORT HIGH CHANCE POP IN THIS REGION....WITH POPS TAPERING TO SLIGHT CHANCE OVER THE SOUTHERN COASTAL PLAINS AND SANDHILLS. MORE CLOUDS THAN SUN WILL LIMIT NORMAL DIURNAL TEMP RISE IN THE WEST-NW WHERE MAX TEMPS EXPECTED TO BE LOWER 80S. PARTIAL SUN OVER THE SE HALF SHOULD WARM TEMPS WELL INTO THE 80S. CONSIDERABLE CLOUDINESS WEDNESDAY NIGHT WILL MAINTAIN HUMID CONDITIONS. MIN TEMPS AROUND 70/LOWER 70S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 318 PM MONDAY... THURSDAY... LINGERING MID-UPPER LEVEL TROUGH WILL MAINTAIN A DECENT THREAT FOR SCATTERED SHOWERS AND THUNDERSTORMS THURSDAY AS LOW LEVEL CONVERGENCE PROJECTED TO BE MAXIMIZED OVER OUR REGION. ONLY CAVEAT IS THAT BUILDING MID-UPPER LEVEL HEIGHTS MAY RESULT IN THE DEVELOPMENT OF A LAYER OF WARM AIR ALOFT...POSSIBLY CAPPING AIR MASS AND LIMITING CONVECTIVE DEVELOPMENT. HOWEVER CONSIDERING THE AMOUNT OF LOW LEVEL CONVERGENCE AND AVAILABLE MOISTURE SUPPORT CHANCE POPS THURSDAY. FRIDAY-SATURDAY....SUB TROPICAL RIDGE PROJECTED TO EXPAND/STRENGTHEN WEST-TO-EAST ACROSS THE LOWER MS VALLEY AND SE U.S. THIS WILL PLACE CENTRAL NC ON THE PERIPHERY OF THIS WEATHER SYSTEM. WEAK PERTURBATIONS TRAVERSING EWD COUPLED WITH AVAILABLE MOISTURE AND INSTABILITY SUGGEST A THREAT FOR SCATTERED SHOWERS AND STORMS EACH DAY...MORE SO ON SATURDAY AFTERNOON AS A S/W IN THE NORTHERN STREAM PROPELS A SFC FRONT SWD TOWARD CENTRAL NC. PLAN TO HAVE CHANCE-SLIGHT CHANCE POPS NW-SE ACROSS THE REGION FRIDAY WITH HIGH CHANCE POPS MOST LOCATIONS LATE SATURDAY-SATURDAY NIGHT. SUNDAY INTO MONDAY....LATEST GFS HAS TRENDED TOWARD THE MORE PROGRESSIVE ECMWF WHICH PUSHES THE SFC COLD FRONT SWD ACROSS CENTRAL NC SUNDAY...AND POSITIONED SOUTH OF THE REGION MONDAY. THIS SUGGEST A DECREASING THREAT FOR SCATTERED SHOWERS AND STORMS. PLAN TO MAINTAIN MENTION OF A SMALL CHANCE BOTH DAYS...SUNDAY TO ACCOUNT FOR POSSIBLE MODEL TIMING ISSUES WITH THE FRONTAL PASSAGE...AND ON MONDAY AS DEVELOPING NW FLOW ALOFT MAY PROVIDE AN AVENUE FOR DISTURBANCES ROTATING AROUND A DEEP CLOSED UPPER LOW OVER THE NORTHERN LAKES TO TRANSLATE INTO OUR REGION. TEMPS THURSDAY THROUGH MONDAY DEPENDENT UPON EXTENT OF CLOUD COVER AND AREAL COVERAGE OF CONVECTION. EXPECT AFTERNOON TEMPS TO AVERAGE A COUPLE OF DEGREES BELOW NORMAL WHILE OVERNIGHT TEMPS WILL BE 3-5 DEGREES ABOVE NORMAL. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 245 PM MONDAY... 24-HR TAF PERIOD: DRY HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL WEAKEN AND MOVE OFFSHORE THE DELMARVA THIS AFTERNOON INTO TONIGHT...WITH A WEAK SOUTHERLY RETURN FLOW DEVELOPING OVER THE REGION AND A SEASONABLY MOIST AIRMASS RETURNING TO CENTRAL AND WESTERN NC. MVFR CEILINGS AND ISOLD SHOWERS WILL BE POSSIBLE AT THE INT/GSO TERMINALS THIS AFT/EVE...THOUGH OVERALL PROBABILITIES WILL BE LOW AND THUNDER APPEARS UNLIKELY. PER 16-17Z VIS SAT AND RADAR IMAGERY...WILL INDICATE VCSH OR A TEMPO GROUP FOR MVFR CEILINGS AND AN ISOLD SHOWER IN THE 18-21Z TIME FRAME AT THE INT/GSO TERMINALS. OTHERWISE... EXPECT VFR CONDITIONS TO PREVAIL THROUGH MIDNIGHT. EXPECT AN INCREASING POTENTIAL FOR MVFR CEILINGS AND ISOLD TO SCT SHOWERS BETWEEN MIDNIGHT AND SUNRISE TUE MORNING AT THE INT/GSO TERMINALS... WITH ISOLD/SCT SHOWERS PERSISTING THROUGH THE REMAINDER OF THE TAF PERIOD. FURTHER EAST AT RDU/FAY/RWI...EXPECT A POTENTIAL FOR MVFR CEILINGS PRIOR TO SUNRISE TUE...WITH AN INCREASING POTENTIAL FOR ISOLD SHOWER ACTIVITY BY TUE AFTERNOON...PRIMARILY AT THE FAY/RDU TERMINALS. LOOKING AHEAD: EXPECT SUB-VFR CONDITIONS TO OCCUR PRIMARILY DURING THE MORNING (06-14Z) HOURS IN ASSOC/W LOW CEILINGS AND/OR FOG...AND DURING THE AFT/EVE HOURS (18-03Z) IN ASSOCIATION WITH ISOLD TO SCT SHOWERS AND THUNDERSTORMS TUE-FRI. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM..WSS LONG TERM...WSS AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
308 PM EDT MON AUG 5 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OVER THE MID ATLANTIC WILL MOVE OFFSHORE TONIGHT. A MOIST SOUTHERLY LOW LEVEL RETURN FLOW WILL PREVAIL THROUGH MID TO LATE WEEK. && .NEAR TERM /THROUGH TUESDAY/... AS OF 300 PM MONDAY... OVERVIEW: SYNOPTIC SUBSIDENCE /HEIGHT RISES/ OVER THE MID-ATLANTIC THIS MORNING WILL WANE AND SHIFT TO NEW ENGLAND THIS AFT/TONIGHT AS AN UPPER LEVEL TROUGH PROGRESSES FURTHER NORTHEAST INTO THE CANADIAN MARITIMES. ACCORDINGLY...1021 MB SFC HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC THIS MORNING WILL WEAKEN AND SHIFT OFFSHORE THE MID- ATLANTIC COAST. AS THE SFC HIGH PROGRESSES EASTWARD AND A LIGHT S/SE RETURN FLOW DEVELOPS OVER THE WESTERN CAROLINAS THIS AFT/EVE...A STATIONARY FRONT EXTENDING EASTWARD FROM NORTHERN GA INTO CENTRAL/UPSTATE SC WILL BEGIN TO LIFT NORTH FROM UPSTATE SC INTO WESTERN NC (ALONG AND WEST OF I-77)...WITH MOISTURE SLOWLY INCREASING TONIGHT ALONG AND WEST OF THE HIGHWAY 1 CORRIDOR. TONIGHT: GIVEN THE AFOREMENTIONED MOISTURE IN ADDITION TO SEASONABLY WEAK MID-LEVEL LAPSE RATES...DIURNAL DESTABILIZATION TODAY WILL BE MARGINAL AND LARGELY CONFINED TO WESTERN PORTIONS OF THE STATE WHERE LOW-LEVEL CONVERGENCE /MOISTURE POOLING/ AND THE SLOW NORTHWARD RETREAT OF THE FRONT WILL CONTRIBUTE TO PERHAPS 250-500 J/KG MLCAPE. GRADUAL LOW-LEVEL MOISTURE RETURN OVERNIGHT WILL RESULT IN A SLOW INCREASE IN MUCAPE...PERHAPS UP TO 500 J/KG IN THE WESTERN PIEDMONT AND 1000 J/KG IN THE FOOTHILLS/MOUNTAINS BY 12Z TUE MORNING. FORCING FOR ASCENT WILL BE CONFINED TO WEAK/SHALLOW LOW-LEVEL CONVERGENCE AND UPSLOPE FLOW IN WESTERN NC THIS AFTERNOON INTO TONIGHT. ALTHOUGH THERE IS AT LEAST A POTENTIAL FOR SMALL AMPLITUDE DISTURBANCES IN W/NW FLOW ALOFT THROUGH TONIGHT...19Z WV IMAGERY AND RAP DATA DO NOT SUGGEST ANY SIGNIFICANT DPVA WILL BE PRESENT. PER 19Z VIS SAT/RADAR IMAGERY INDICATING SHALLOW AGITATED CU AND A FEW BRIEF SHOWERS IN THE WEST...WILL INDICATE A SLIGHT CHANCE OF SHOWERS THROUGH THIS EVENING. INCREASINGLY MOIST LOW-LEVEL UPSLOPE FLOW AND A RELATIVELY BETTER CHANCE FOR SMALL AMPLITUDE DISTURBANCES ALOFT SHOULD RESULT IN A BETTER CHANCE FOR ISOLD/SCT SHOWERS IN THE WESTERN PIEDMONT PRIOR TO SUNRISE TUE...SUPPORTED BY THE LATEST HIGH-RES CONVECTION ALLOWING MODELS. WILL INDICATE INCREASING PRECIP CHANCES. EXPECT LOWS TONIGHT NEAR OR SLIGHTLY BELOW NORMAL...IN THE LOWER TO UPPER 60S...WARMEST IN THE WEST/SW PIEDMONT WHERE MORE CLOUD COVER AND BETTER LOW-LEVEL MOISTURE WILL BE PRESENT AND COOLEST IN THE TYPICAL AREAS OF THE NORTHERN PIEDMONT AND NE COASTAL PLAIN WHERE A DRIER AIRMASS AND LESS CLOUD COVER (AT LEAST INITIALLY) WILL PREVAIL. TUESDAY: EXPECT AN INCREASING POTENTIAL FOR SHOWER (THUNDERSTORM) ACTIVITY TUESDAY MORNING (AFTERNOON) AS A SEASONABLY MOIST SOUTHERLY LOW-LEVEL RETURN FLOW AIDS IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION IN THE PRESENCE OF WEAK LOW-LEVEL CONVERGENCE AND AN INCREASED POTENTIAL FOR SMALL AMPLITUDE DISTURBANCES IN NW FLOW ALOFT. WILL INDICATE PRECIP CHANCES RANGING FROM 20-50%...HIGHEST IN THE WESTERN PIEDMONT AND LOWEST IN THE COASTAL PLAIN WHERE LOW-LEVEL MOISTURE /DIURNAL DESTABILIZATION/ IS EXPECTED TO BE MARGINAL. HIGHS WILL BE SIMILAR TO TODAY AND PRIMARILY DEPEND ON CLOUD COVER... RANGING FROM NEAR 80F IN THE N/NW PIEDMONT TO MID/UPPER 80S IN THE SANDHILLS AND COASTAL PLAIN. -VINCENT && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... AS OF 250 AM MONDAY... FOR WEDNESDAY/WEDNESDAY NIGHT: A WEAK MID LEVEL WAVE EXTENDING FROM LAKE ERIE TO KY/TN EARLY WED WILL SHIFT EASTWARD ACROSS THE APPALACHIANS TO THE NORTHEAST STATES THROUGH WED NIGHT. THIS WAVE WILL SERVE AS A WEAK/DIFFUSE WARM FRONT ALOFT AS THE TX RIDGE BUILDS A BIT TO THE NE AND THE FAST WESTERLIES OVER THE NRN TIER OF THE CONUS FLATTENS OUT. THE SOUTHERN PORTION OF THIS WAVE APPEARS TO CONSIST OF ENERGY EMANATING FROM MCS ACTIVITY OVER MO EARLY TUE... SO EXPECT THIS MCV TO BRING COPIOUS MID LEVEL CLOUDINESS WEDNESDAY... RESULTING IN MOSTLY CLOUDY TO CLOUDY SKIES AREAWIDE. THE INCREASING SOUTHERLY LOW LEVEL FLOW SHOULD BE MOST PRONOUNCED OVER THE MOUNTAINS INTO THE WRN CWA... WHERE LOW LEVEL MASS CONVERGENCE WILL BE ENHANCED ALONG/AHEAD OF THE INCOMING 850 MB FRONT. FORECAST SOUNDINGS SHOW GREATER MOISTURE THROUGH THE COLUMN IN THE WRN CWA WHILE THE AIR BENEATH 600 MB IS DRIER IN THE EAST... AND THE MID LEVEL WARMING CENTERED AROUND 500 MB SHOULD LIMIT INSTABILITY... WITH MODELS GENERALLY SHOWING 1000 J/KG OR LESS IN THE WRN CWA ONLY. BUT THE INCREASING PW VALUES TO AROUND 2 INCHES IN THIS AREA WARRANT GOOD CHANCE POPS IN THE WRN CWA RANGING TO JUST SLIGHT CHANCE IN THE FAR ERN CWA... TAPERING OFF BY LATE EVENING. THICKNESSES ABOUT 10 M BELOW NORMAL WITH PLENTY OF CLOUDS SUPPORT HIGHS AROUND A CATEGORY BELOW NORMAL... 83-87. CONTINUED MOSTLY CLOUDY OVERNIGHT AS THE SKY BEHIND SLOWLY-DEPARTING HIGH-BASED STRATOCU FILLS IN WITH FOG/STRATUS OVERNIGHT. LOWS 68-72. FOR THURSDAY/THURSDAY NIGHT: RELATIVELY DRY. FAST AND FLAT FLOW CONTINUES THU MORNING FROM THE EASTERN ROCKIES AND GREAT PLAINS EASTWARD THROUGH THE OH VALLEY AND GREAT LAKES TO THE MIDATLANTIC AND NORTHEAST. MEANWHILE THE TX RIDGE EXPANDS EASTWARD OVER THE GULF AND SOUTHEAST STATES... A REACTION TO A VORTICITY MAX MOVING FROM THE FOUR CORNERS EAST INTO THE TROUGH BASE OF A STRONG VORTEX CENTERED OVER THE MANITOBA/ONTARIO BORDER. THIS WILL RESULT IN VERY WEAK AND ILL-DEFINED MID LEVEL FLOW OVER NC... NOTED ON NAM/GFS FORECAST SOUNDINGS DEPICTING CONSIDERABLE DRYING ALOFT. AT THE SURFACE... A STRENGTHENING FRONTAL ZONE FROM OK THROUGH THE OH VALLEY TO NEW ENGLAND WILL MOVE LITTLE THROUGH THU NIGHT AS IT WAITS FOR THE CANADA VORTEX TO AMPLIFY SLIGHTLY STARTING FRIDAY... AND THE WEAK LEE TROUGH WILL HOLD OVER THE VA/NC PIEDMONT. THE BETTER LOW LEVEL MOISTURE FLUX WILL BE DEFLECTED TO OUR WEST AND NORTH THROUGH THU NIGHT... IN THE BETTER WARM/MOIST CONVEYOR ZONE... AND PW OVER NC SLIPS TO A RELATIVE MINIMUM. HAVE HELD POPS AT JUST LOW CHANCE MAINLY ACROSS THE FAR WEST AND NRN CWA... ON THE EDGE OF THE RIDGE CORE. WITH FEWER CLOUDS AND AN ASSOCIATED UPTICK OF THICKNESSES TO JUST A BIT BELOW NORMAL... EXPECT HIGHS OF 86-90. SHOULD SEE INCREASING AND THICKENING/LOWERING MID CLOUDS THU NIGHT AS WEAK WESTERLY STEERING FLOW BRINGS BLOWOFF CLOUDS FROM OH VALLEY AND MID MISS VALLEY CONVECTION. LOWS 69-74. -GIH && .LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 220 AM MONDAY... STILL APPEARS THAT WE`LL SEE WET WEATHER FRIDAY/SATURDAY WITH SOME IMPROVEMENT POSSIBLE FOR SUNDAY. THE CANADIAN VORTEX WOBBLES EASTWARD ACROSS ONTARIO TO CENTRAL QUEBEC DURING THIS TIME FRAME... RESULTING IN A SLIGHT SOUTHWARD DIP TO THE WESTERLIES AND EVENTUAL EVOLUTION TO A WNW STEERING FLOW OVER NC BY SUNDAY. THE SURFACE FRONT ACROSS THE OH VALLEY AND NORTHEAST STATES EARLY FRIDAY BECOMES MORE E/W ORIENTED IN RESPONSE TO THIS EASTWARD MOVEMENT OF THE SHALLOW LONGWAVE TROUGH... AND THE LEE TROUGH SHARPENS OVER CENTRAL VA/NC AS BOTH 850 MB WINDS AND PW VALUES INCREASE WITHIN THE ENCROACHING WARM/MOIST CONVEYOR ZONE. EXPECT ABOVE-NORMAL LOWS AND SLIGHTLY BELOW-NORMAL HIGHS FRIDAY/SATURDAY AS WARM THICKNESSES ARE OFFSET BY CLOUDS AND A GOOD CHANCE OF SHOWERS/STORMS. GFS/ECMWF PUSH THE SURFACE FRONT TO SC AND ERN NC BY SUNDAY AS THE AXIS OF THE BROAD LONGWAVE TROUGH SHIFTS OVERHEAD AND JUST TO OUR EAST. WILL RETAIN LOW CHANCE POPS AREAWIDE BUT A LITTLE HIGHER IN THE EAST/SOUTH AS THE FRONT COULD HANG UP IN THE VICINITY. TEMPS NEAR TO SLIGHTLY BELOW NORMAL... ALTHOUGH THIS (ALONG WITH THE SURFACE FRONT POSITION ON SUNDAY) IS FAR FROM CERTAIN. -GIH && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 245 PM MONDAY... 24-HR TAF PERIOD: DRY HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL WEAKEN AND MOVE OFFSHORE THE DELMARVA THIS AFTERNOON INTO TONIGHT...WITH A WEAK SOUTHERLY RETURN FLOW DEVELOPING OVER THE REGION AND A SEASONABLY MOIST AIRMASS RETURNING TO CENTRAL AND WESTERN NC. MVFR CEILINGS AND ISOLD SHOWERS WILL BE POSSIBLE AT THE INT/GSO TERMINALS THIS AFT/EVE...THOUGH OVERALL PROBABILITIES WILL BE LOW AND THUNDER APPEARS UNLIKELY. PER 16-17Z VIS SAT AND RADAR IMAGERY...WILL INDICATE VCSH OR A TEMPO GROUP FOR MVFR CEILINGS AND AN ISOLD SHOWER IN THE 18-21Z TIME FRAME AT THE INT/GSO TERMINALS. OTHERWISE... EXPECT VFR CONDITIONS TO PREVAIL THROUGH MIDNIGHT. EXPECT AN INCREASING POTENTIAL FOR MVFR CEILINGS AND ISOLD TO SCT SHOWERS BETWEEN MIDNIGHT AND SUNRISE TUE MORNING AT THE INT/GSO TERMINALS... WITH ISOLD/SCT SHOWERS PERSISTING THROUGH THE REMAINDER OF THE TAF PERIOD. FURTHER EAST AT RDU/FAY/RWI...EXPECT A POTENTIAL FOR MVFR CEILINGS PRIOR TO SUNRISE TUE...WITH AN INCREASING POTENTIAL FOR ISOLD SHOWER ACTIVITY BY TUE AFTERNOON...PRIMARILY AT THE FAY/RDU TERMINALS. LOOKING AHEAD: EXPECT SUB-VFR CONDITIONS TO OCCUR PRIMARILY DURING THE MORNING (06-14Z) HOURS IN ASSOC/W LOW CEILINGS AND/OR FOG...AND DURING THE AFT/EVE HOURS (18-03Z) IN ASSOCIATION WITH ISOLD TO SCT SHOWERS AND THUNDERSTORMS TUE-FRI. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM..SMITH/HARTFIELD LONG TERM...HARTFIELD AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
101 PM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 1250 PM CDT MON AUG 5 2013 CLOUDS CONTINUE TO SLOWLY DIMINISH ACROSS THE AREA BUT IT WILL BE HIGHLY VARIABLE AS FAR AS TIMING GOES. THE FAR NW FA HAS CLEARED OUT SO WOULD EXPECT THE COOPERSTOWN...KGFK AND KHCO AREAS TO THIN OUT IN THE NEXT HOUR OR SO. IT WILL STILL TAKE LONGEST FOR THE EASTERN FA TO CLEAR SO IT SHOULD STAY THE COOLEST THERE FOR HIGH TEMPS. REST OF THE AREA WILL SEE A SLOW TEMP RECOVERY AS IT WILL TAKE SOME SUN TO REACH HIGHS IN THE 70S. THEREFORE IT WILL LIKELY BE A LATE AFTERNOON HIGH FOR MOST AREAS. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 SURFACE TROUGH WILL CONTINUE TO PROPAGATE THROUGH THE FA. SCATTERED SHOWERS ACROSS THE EASTERN FA SHOULD BE EAST OF THE REGION BY 12Z. WEAK HIGH PRESSURE WILL MOVE INTO THE REGION. THE MAIN CHALLENGE FOR TODAY WILL BE CLOUDS AND ASSOCIATED TEMPERATURES. THERE IS AN AREA OF LOW CLOUDS BEHIND THE SURFACE TROUGH...ALONG THE INTERNATIONAL BORDER. THIS AREA OF CLOUDS HAS BEEN ADVECTING SOUTHWARD OVER THE PAST FEW HOURS...AND THE LATEST RAP GUIDANCE INDICATES THAT THIS TREND WILL CONTINUE. FOLLOWING THIS GUIDANCE MOST AREAS (EXCEPT PORTIONS OF SOUTHEAST NORTH DAKOTA) WILL LIKELY BE MOSTLY CLOUDY INTO AT LEAST THE EARLY AFTERNOON HOURS. THE THOUGHT IS THAT THE CLOUDS SHOULD BEGIN TO DISSIPATE ENOUGH BY MID-LATE AFTERNOON FOR MAX TEMPS TO BE ABLE TO REACH INTO THE MID-UPPER 70S. THE NEXT UPPER LEVEL WAVE AND ASSOCIATED SURFACE TROUGH/COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT INTO TUESDAY. FORCING AND INSTABILITY APPEAR TO BE STRONGER THAN THIS PAST SYSTEM...WHICH COULD LEAD TO MORE WIDESPREAD ACTIVITY. THE BEST SEVERE POTENTIAL WILL BE SOUTH OF THE FA WHERE INSTABILITY IS STRONGEST. HOWEVER...DEEP LAYER SHEAR WILL BE STRONG AND A FEW STRONGER STORMS WOULD SEEM POSSIBLE (ESPECIALLY TUESDAY AFTERNOON ACROSS SE ND INTO WC MN WHERE THE SFC FRONT WILL BE LOCATED DURING PEAK HEATING). .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 TUESDAY NIGHT-WEDNESDAY NIGHT...HIGH PRESSURE WILL AGAIN MOVE INTO THE REGION WHICH SHOULD LEAD TO MOSTLY DRY CONDITIONS. THURSDAY-SUNDAY NIGHT...00 UTC GFS/ECMWF SHOW SAME BASIC SYNOPTIC PATTERN...BUT DIFFER ON THE SPEED AT WHICH THE CLOSED CANADIAN LOW EJECTS INTO QUEBEC. THE ECMWF IS QUICKER THAN THE GFS AND THIS ALLOWS ANOTHER PACIFIC SHORT-WAVE TO MOVE INTO THE NORTHERN PLAINS NEXT WEEKEND. THE SLOWER GFS MAINTAINS DRY NORTHWEST FLOW ACROSS THE FORECAST AREA. GIVEN MODEL DIFFERENCES...WILL KEEP A MAINLY DRY FORECAST FRIDAY AND BEYOND. BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE THURSDAY AS ANOTHER COLD FRONT SWEEPS ACROSS THE REGION. COLD POOL ALOFT ASSOCIATED WITH DEEP CLOSED LOW WILL KEEP TEMPERATURES WELL BELOW MID-AUGUST NORMALS. HIGHS THURSDAY/ FRIDAY WILL STRUGGLE TO BREAK 70 DEGREES IN PLACES. A GRADUAL WARM-UP IS EXPECTED INTO THE WEEKEND...BUT STILL 5 TO 10 DEGREES COOLER THAN NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 101 PM CDT MON AUG 5 2013 MFVR CIGS TO CONTINUE TO LIFT AND SCT OUT THIS AFTERNOON IN THE VALLEY AND EVENING AT BJI. VFR OVERNIGHT WITH A POSSIBILITY OF SOME THUNDER IN THE DVL BSN. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...GODON SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...JK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1250 PM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 1250 PM CDT MON AUG 5 2013 CLOUDS CONTINUE TO SLOWLY DIMINISH ACROSS THE AREA BUT IT WILL BE HIGHLY VARIABLE AS FAR AS TIMING GOES. THE FAR NW FA HAS CLEARED OUT SO WOULD EXPECT THE COOPERSTOWN...KGFK AND KHCO AREAS TO THIN OUT IN THE NEXT HOUR OR SO. IT WILL STILL TAKE LONGEST FOR THE EASTERN FA TO CLEAR SO IT SHOULD STAY THE COOLEST THERE FOR HIGH TEMPS. REST OF THE AREA WILL SEE A SLOW TEMP RECOVERY AS IT WILL TAKE SOME SUN TO REACH HIGHS IN THE 70S. THEREFORE IT WILL LIKELY BE A LATE AFTERNOON HIGH FOR MOST AREAS. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 SURFACE TROUGH WILL CONTINUE TO PROPAGATE THROUGH THE FA. SCATTERED SHOWERS ACROSS THE EASTERN FA SHOULD BE EAST OF THE REGION BY 12Z. WEAK HIGH PRESSURE WILL MOVE INTO THE REGION. THE MAIN CHALLENGE FOR TODAY WILL BE CLOUDS AND ASSOCIATED TEMPERATURES. THERE IS AN AREA OF LOW CLOUDS BEHIND THE SURFACE TROUGH...ALONG THE INTERNATIONAL BORDER. THIS AREA OF CLOUDS HAS BEEN ADVECTING SOUTHWARD OVER THE PAST FEW HOURS...AND THE LATEST RAP GUIDANCE INDICATES THAT THIS TREND WILL CONTINUE. FOLLOWING THIS GUIDANCE MOST AREAS (EXCEPT PORTIONS OF SOUTHEAST NORTH DAKOTA) WILL LIKELY BE MOSTLY CLOUDY INTO AT LEAST THE EARLY AFTERNOON HOURS. THE THOUGHT IS THAT THE CLOUDS SHOULD BEGIN TO DISSIPATE ENOUGH BY MID-LATE AFTERNOON FOR MAX TEMPS TO BE ABLE TO REACH INTO THE MID-UPPER 70S. THE NEXT UPPER LEVEL WAVE AND ASSOCIATED SURFACE TROUGH/COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT INTO TUESDAY. FORCING AND INSTABILITY APPEAR TO BE STRONGER THAN THIS PAST SYSTEM...WHICH COULD LEAD TO MORE WIDESPREAD ACTIVITY. THE BEST SEVERE POTENTIAL WILL BE SOUTH OF THE FA WHERE INSTABILITY IS STRONGEST. HOWEVER...DEEP LAYER SHEAR WILL BE STRONG AND A FEW STRONGER STORMS WOULD SEEM POSSIBLE (ESPECIALLY TUESDAY AFTERNOON ACROSS SE ND INTO WC MN WHERE THE SFC FRONT WILL BE LOCATED DURING PEAK HEATING). .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 348 AM CDT MON AUG 5 2013 TUESDAY NIGHT-WEDNESDAY NIGHT...HIGH PRESSURE WILL AGAIN MOVE INTO THE REGION WHICH SHOULD LEAD TO MOSTLY DRY CONDITIONS. THURSDAY-SUNDAY NIGHT...00 UTC GFS/ECMWF SHOW SAME BASIC SYNOPTIC PATTERN...BUT DIFFER ON THE SPEED AT WHICH THE CLOSED CANADIAN LOW EJECTS INTO QUEBEC. THE ECMWF IS QUICKER THAN THE GFS AND THIS ALLOWS ANOTHER PACIFIC SHORT-WAVE TO MOVE INTO THE NORTHERN PLAINS NEXT WEEKEND. THE SLOWER GFS MAINTAINS DRY NORTHWEST FLOW ACROSS THE FORECAST AREA. GIVEN MODEL DIFFERENCES...WILL KEEP A MAINLY DRY FORECAST FRIDAY AND BEYOND. BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE THURSDAY AS ANOTHER COLD FRONT SWEEPS ACROSS THE REGION. COLD POOL ALOFT ASSOCIATED WITH DEEP CLOSED LOW WILL KEEP TEMPERATURES WELL BELOW MID-AUGUST NORMALS. HIGHS THURSDAY/ FRIDAY WILL STRUGGLE TO BREAK 70 DEGREES IN PLACES. A GRADUAL WARM-UP IS EXPECTED INTO THE WEEKEND...BUT STILL 5 TO 10 DEGREES COOLER THAN NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1250 PM CDT MON AUG 5 2013 WILL BE COMING SOON. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...GODON SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...JK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
310 PM CDT MON AUG 5 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 310 PM CDT MON AUG 5 2013 THE NEXT 24 TO 36 HOURS WILL FEATURE A MORE ACTIVE PERIOD WITH A FEW WEATHER SYSTEMS TO CONTEND WITH INCLUDING PRECIPITATION CHANCES THIS EVENING...FOG OVERNIGHT...AND THEN SEVERE THREAT TUESDAY AFTERNOON/EVENING. LATEST WATER VAPOR COMBINED WITH RAP 500MB HEIGHTS SHOW BROAD NORTHWEST FLOW EAST OF THE ROCKIES...WITH NUMEROUS EMBEDDED SHORTWAVE TROUGHS. ONE CURRENTLY MOVING THROUGH MINNESOTA/IOWA...WHILE UPSTREAM ACROSS ALBERTA SITS A MORE VIGOROUS WAVE. FINALLY...A CLOSED POLAR VORTEX RESIDES NEAR HUDSON BAY. FOR THIS EVENING INTO TONIGHT...WILL CARRY A SLIGHT CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS UNTIL UPPER LEVEL SHORTWAVE COMPLETELY EXITS THE AREA. DESPITE SURFACE TROUGH LAGGING BEHIND...AND BUILDING INSTABILITY WITH CLEARING SKIES...SUBSIDENCE IN THE WAKE OF THE UPPER LEVEL SHORTWAVE AND SOME LOW TO MID LEVEL DRYING SHOULD PRECLUDE THE DEVELOPMENT OF ADDITIONAL SHOWERS/STORMS. HAVE ADDED PATCHY TO AREAS OF FOG FOR PARTS OF WISCONSIN...INCLUDING THE MS AND WISCONSIN RIVER VALLEYS OVERNIGHT AS A WEAK SURFACE HIGH BUILDS IN THE WAKE OF THE DEPARTING SYSTEM AND AHEAD OF THE APPROACHING COLD FRONT. NICE SETUP WITH TODAY/S COOL...CLOUDY CONDITIONS AND RECENT RAINFALL...THEN CLEARING SKIES LATE THIS EVENING. SURFACE WIND FIELD DROPS TO 5 KTS OR LESS...AND SOUNDINGS SHOW DECENT BOUNDARY LAYER SATURATION THOUGH TRY TO SHOW A STIFF BREEZE AT ABOUT 500 FT. COULD BE A MORE WIDESPREAD FOG SCENARIO INSTEAD OF JUST THE RIVER VALLEYS...SOMETHING TO WATCH THIS EVENING. THE ALBERTA SHORTWAVE TROUGH THEN TAKES AIM ON THE AREA...AND WILL BE THE FOCUS FOR PUSHING THROUGH A SURFACE COLD FRONT TUESDAY EVENING. BUILDING INSTABILITY DURING THE DAY IS SOMEWHAT CONDITIONAL ON AN EARLY MORNING MCS EXPECTED WELL TO OUR WEST...BUT BY MID AFTERNOON...MUCAPE BETWEEN 1500 AND 2000 J/KG COULD BE REALIZED. THE SHEAR ENVIRONMENT IS MORE THAN SUFFICIENT FOR SEVERE STORMS AS 250 MB JET MAX OVERHEAD PUTS 40 TO 50 KTS OF EFFECTIVE SHEAR ACROSS MUCH OF THE AREA...AND THE LOW-LEVELS HAVE FAVORABLE LAPSE RATES. HODOGRAPHS SHOW MODEST LOOPING. OVERALL...IF INSTABILITY CONDITIONS ARE MET...ENVISION STORM MODE TO FAVOR RIGHT MOVING CLUSTER OF CELLS EVOLVING INTO BOWING SEGMENTS WITH THE MAIN THREAT LARGE HAIL AND DAMAGING WINDS. 0-1 KM SHEAR ENVIRONMENT IS UNIDIRECTIONAL SO NOT EXPECTING A FAVORABLE TORNADO ENVIRONMENT HOWEVER WITH THAT SAID...ANY LINGERING SURFACE BOUNDARIES COULD COMPLICATE THAT. MODEL AGREEMENT ON FRONTAL TIMING IS HIGHER WITH THE 05.12Z GUIDANCE...WHICH ADDS CONFIDENCE TO THE LATE AFTERNOON AND EVENING PRECIPITATION CHANCES. THE NAM REMAINS A FASTER OUTLIER WHILE THE GEM/GFS/ECMWF ARE CONSISTENT WITH A 00 TO 06Z PASSAGE. EARLIER FORECAST TIMING FOR POPS LOOK GOOD SO HAVE CARRIED SIMILAR THINKING. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 310 PM CDT MON AUG 5 2013 THE BIG STORY IN THE LONG TERM WILL BE A CONTINUATION OF THE UNSEASONABLY COOL WEATHER PATTERN AS THE MAIN POLAR VORTEX / CLOSED UPPER LOW WOBBLES ACROSS SOUTHERN CANADA. OUTSIDE OF SCATTERED DAYTIME CUMULUS FIELD ACROSS WISCONSIN WEDNESDAY...HIGH PRESSURE DOMINATES WITH PLEASANT CONDITIONS. HIGHS LOWER TO MIDDLE 70S. ANOTHER SIMILAR DAY THURSDAY...THOUGH BY EVENING INTO THE NIGHT THE CLOSED UPPER LOW WOBBLES FURTHER TO THE SOUTH AS ANOTHER PIECE OF ENERGY ROUNDS THE BASE. THIS TRIES TO DRIVE A SURFACE COLD FRONT WITH SHOWERS AND THUNDERSTORMS ACROSS CENTRAL MINNESOTA INTO WISCONSIN. HOWEVER...BETTER DYNAMICS AND MOISTURE TRANSPORT REMAIN IN THE WEST AND NORTH FORECAST...AND THE FRONT WASHES OUT BEFORE MAKING IT VERY FAR INTO THE FORECAST AREA. WILL CONTINUE SLIGHT CHANCES IN THE NORTHWEST WHILE THE REST OF THE AREA WILL LIKELY ONLY SEE INCREASED CLOUD COVER. IN THE WAKE OF THIS SHORTWAVE TROUGH...A REINFORCING SHOT OF COOLER AIR SURGES IN AS SEEN BY 850 MB TEMPERATURES FRIDAY AND SATURDAY DROPPING TO THE 8 TO 10C RANGE. HIGHS IN THE 70S AND OVERNIGHT LOWS COULD DIP INTO THE UPPER 40S TO LOWER 50S...ESPECIALLY FOR THE TYPICAL COOLER SPOTS OF CENTRAL WISCONSIN. DEPENDING ON THE HIGH PRESSURE AXIS...COULD SEE A FEW MORNINGS OF RIVER VALLEY FOG AS WELL. OVERALL...VERY NICE CONDITIONS FOR EARLY/MID AUGUST POSSIBLE ACROSS THE ENTIRE UPPER MIDWEST FROM FRIDAY INTO EARLY NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1221 PM CDT MON AUG 5 2013 AN UPPER LEVEL DISTURBANCE CONTINUED TO SLIDE SOUTHEAST ACROSS MN/WI AT MID DAY. BULK OF THE SHRA/TSRA HAD MOVED SOUTHEAST OF THE TAF SITES...WITH THE MAIN FORCING/LIFT ALSO MOVING OFF TO THE EAST/ SOUTH. LEFT 18Z TAF SET SHRA/TSRA-FREE WITH CONVECTION FOR THE REST OF THE AFTERNOON/EVENING LOOKING TO BE WDLY SCT AT MOST WITH MUCH UNCERTAINTY IF ONE WOULD CROSS EITHER THE KRST/KLSE AIRPORTS. BIGGER CONCERN IS LOWER LEVEL MOISTURE/CLOUDS IN THE WAKE OF THIS MORNING/S CONVECTION ADVECTING INTO THE AREA ON SOUTH WINDS. RATHER WIDESPREAD MVFR AND LCL IFR CIGS AROUND THE AREA AT MID-DAY. WITH THE MAIN LOWER LEVEL TROUGH REMAINING WEST OF THE AREA...THESE LOOKING TO PERSIST THRU THE AFTERNOON INTO THE EVENING. MODEL CONSENSUS BUILDS WEAK HIGH PRESSURE INTO THE AREA LATER THIS EVENING/OVERNIGHT. CONTINUED THE TREND OF THE LOWER CLOUD DECKS BECOMING SCT BY LATE EVENING...BUT WITH THE MOIST BOUNDARY LAYER FROM THIS MORNINGS RAINS THIS SETS THE AREA UP FOR RADIATIONAL BR/FG LATER TONIGHT INTO TUE MORNING. ADDED VCFG AND TEMPO 2SM BR TO KLSE IN THE 9-14Z PERIOD AND MVFR BR TO KRST IN ROUGHLY THE SAME PERIOD. ONCE THE BR/FG LIFT/BURN OFF TUE MORNING...GENERALLY GOOD VFR THEN EXPECTED THRU MUCH OF TUE WITH SOME DRIER IN THE 925-850MB LAYER MIXING TOWARD THE SFC WITH DIURNAL WARMING/MIXING THRU THE DAY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...ZT LONG TERM....ZT AVIATION.....RRS