Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/15/13


AREA FORECAST DISCUSSION
NWS PUEBLO CO
1115 AM MDT TUE AUG 13 2013 .UPDATE... ISSUED AT 841 AM MDT TUE AUG 13 2013 HAVE CUT BACK POPS TO ZEROS...BASED ON NEAR ZERO CLOUDS ACROSS THE CWA. WILL SEE A SLOW BUT STEADY INCREASE IN CONVECTION BY THIS AFTERNOON...FIRST ACROSS THE MTS AND THEN SPREADING EWD TO THE PLAINS. LOOKS LIKE A PRETTY TYPICAL AUG DAY. ROSE && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 528 AM MDT TUE AUG 13 2013 ...FLASH FLOOD THREAT FOR BURN SCARS IN EL PASO/TELLER COUNTIES TODAY... MOST OF SHOWER/TSTORM ACTIVITY HAS DIMINISHED ACROSS THE AREA THIS MORNING AND MODELS ARE HAVING A DIFFICULT TIME WITH THIS AS BOTH NAM12 AND GFS MAINTAIN PRECIPITATION ACROSS THE SOUTHEAST PLAINS THROUGH THE MORNING HOURS. THIS LEADS TO LOWER CONFIDENCE IN QPF FORECAST TODAY AS MODELS PLAY CATCH UP WITH WHAT IS CURRENTLY GOING ON. IN WV PICS...APPEARS MAIN SHORTWAVE WHICH HELPED FIRE OFF YESTERDAY`S CONVECTION HAS ALREADY PUSHED EAST OF THE AREA INTO CENTRAL KS. HOWEVER...ANOTHER SHORTWAVE IS EVIDENT IN THE MOISTURE PLUME ACROSS NW CO/SRN WY...WHICH WILL BE TRANSLATING SLOWLY EASTWARD THROUGH THE UPPER RIDGE ACROSS THE AREA TODAY. AT THE SFC...DEW POINTS HAVE INCREASED ACROSS THE PLAINS WITH READINGS MAINLY IN THE 50S. STRATUS IS NOT AS WIDESPREAD AS MODELS PORTRAYED...PROBABLY A RESULT OF THEIR OVERZEALOUS QPF FORECAST THIS MORNING. SUSPECT WE WILL SEE SOME STRATUS DEVELOP AND SPREAD WESTWARD INTO SOUTHEAST PLAINS TOWARDS DAWN BUT IT WILL PROBABLY BE FAIRLY SHALLOW AND MORE PATCHY IN NATURE EXCEPT ACROSS THE SE CORNER WHERE IT MAY BE MORE WIDESPREAD. THUS ANY STRATUS WILL LIKELY BURN OFF FAIRLY QUICKLY THIS MORNING. WITH MORE CLEARING THIS AFTERNOON...WE WILL BE MORE LIKELY TO SEE SUFFICIENT HEATING TO TRIGGER ANOTHER ROUND OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHEAST MOUNTAINS AND ADJACENT PLAINS. WITH LOW LEVEL FLOW REMAINING EASTERLY...DEW POINTS SHOULD REMAIN IN THE 50S ACROSS THE PLAINS/I-25 CORRIDOR. THIS WILL LEAD TO CAPE VALUES GENERALLY BETWEEN 500-1000 J/KG...NOT TERRIBLY HIGH...BUT SUFFICIENT TO PRODUCE A FEW STRONG STORMS. THUS GREATEST CONCERN WILL BE THE EL PASO/TELLER COUNTY AREAS WHERE THE SUSCEPTIBLE BURN SCARS WILL BE UNDER THE GUN FOR MORE HEAVY RAINFALL TODAY. ALTHOUGH NAM12 HAS TAMED DOWN ITS QPF FCST FOR TODAY VS YESTERDAY`S RUNS...OTHER MODELS SUCH AS GFS...HIGH RES WRF (LOCAL AND NSSL)AND HRRR BOTH HIT PORTIONS OF THE SE MTS/ADJACENT PLAINS WITH POCKETS OF HEAVY RAINFALL. WITH THE SATURATED GROUND FROM RECENT RAINS ACROSS TELLER AND EL PASO COUNTY...WILL BE PUTTING OUT ANOTHER FLASH FLOOD WATCH FOR TODAY. GREATEST THREAT WINDOW APPEARS TO BE FROM 2 PM TO 6 PM FOR THE BURN SCARS THOUGH HRRR SEEMS TO BE TRENDING IT TOWARDS 1 PM IN SOME OF ITS LATER RUNS. OF COURSE IF THE STRONGER STORMS PASS AROUND THE BURN SCARS...THEN IT IS POSSIBLE THAT FLASH FLOODING WILL NOT OCCUR...BUT WILL ERR ON THE SIDE OF CAUTION AS THE PROBABILITY WILL BE THERE FOR A HIGH IMPACT EVENT SHOULD THE BURN SCARS BE IMPACTED. THE CITY OF COLORADO SPRINGS COULD ALSO BE UNDER THE GUN TODAY FOR FLASH FLOODING DUE TO THE SATURATED GROUND FROM YESTERDAY`S HEAVY RAIN WHICH WILL EXACERBATE ANY RUNOFF TODAY SHOULD STORMS HIT THAT REGION. THUNDERSTORMS SHOULD SPREAD EASTWARD ACROSS THE PLAINS DURING THE LATE AFTERNOON AND EVENING HOURS AS THE SHORTWAVE SLOWLY KICKS THROUGH THE REGION. WILL DECREASE POPS QUICKLY AFTER 06Z AS CONSENSUS OF THE MODELS IS TO KEEP CONVECTION GOING WELL TO THE SOUTH ALONG FRONTAL BOUNDARY ACROSS EASTERN NM/SRN TX PANHANDLE. GFS SEEMS TO BE THE OUTLIER IN KEEPING WIDESPREAD QPF ACROSS THE PLAINS THROUGH 12Z...SO WILL DISCOUNT IT FOR NOW. STRATUS SHOULD BE MORE WIDESPREAD ACROSS THE SE PLAINS TONIGHT. NOT TO NEGLECT WESTERN AREAS...DRIER AIR OUT THAT WAY SHOULD KEEP PCPN EFFICIENCIES WITH THUNDERSTORMS LOWER. PRECIP WATERS WILL BE RUNNING AROUND .50 WHICH PUTS THEM BELOW 100% OF NORMAL. WITH FORCING FROM THE SHORTWAVE EXPECTED TO IMPACT NORTHERN AREAS MORE SO THAN THE SOUTHWEST...EXPECT THUNDERSTORMS TO BE MORE ISOLATED TO SCATTERED IN COVERAGE ACROSS THE EASTERN SAN JUANS AND LA GARITAS...AND WILL DIMINISH QUICKLY DURING THE EVENING HOURS. THE WEST FORK BURN SCAR WILL NEED TO BE MONITORED FROM NOON TO 6 PM FOR POCKETS OF HEAVIER RAIN SUFFICIENT TO CAUSE LOCALIZED RUNOFF/POTENTIAL FLASH FLOOD PROBLEMS. -KT .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 528 AM MDT TUE AUG 13 2013 LONGER TERM METEOROLOGICAL CONCERNS INCLUDE POPS AND TEMPERATURES. ABOVE SEASONAL POPS IN COMBINATION WITH BELOW SEASONAL TEMPERATURES ARE EXPECTED FROM WEDNESDAY INTO WEDNESDAY NIGHT AS AVAILABLE ATMOSPHERIC MOISTURE INTERACTS WITH THE DAILY OROGRAPHIC HEATING CYCLE AS WELL AS SOME UPPER LIFT. RECENT LONGER TERM FORECAST MODEL SOUNDINGS INDICATE THAT LOCATIONS SUCH AS THE I-25 CORRIDOR SHOULD EXPERIENCE PRECIPITABLE WATER VALUES NEARING ONE INCH AT TIMES WEDNESDAY AFTERNOON. THE COMBINATION OF AVAILABLE ATMOSPHERIC MOISTURE AND AN APPROACHING UPPER SHORT-WAVE(PER LATEST GFS40 PV15 FORECAST) ...ESPECIALLY OVER NORTHERN SECTIONS OF THE FORECAST DISTRICT SHOULD ALLOW FOR ANOTHER ROUND OF ISOLATED TO SCATTERED WEDNESDAY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS OVER THE FORECAST DISTRICT...ESPECIALLY EASTERN SECTIONS. ONCE AGAIN...SOME OF THESE STORMS ON WEDNESDAY AFTERNOON AND EVENING WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL AS WELL AS POTENTIAL BURN SCAR FLOODING ISSUES...ESPECIALLY IF A STRONGER STORM DEVELOPS OVER A BURN SCAR...SUCH AS THE WALDO CANYON BURN SCAR...ETC. WFO PUEBLO WILL CONTINUE TO MONITOR CLOSELY AND ISSUE HYDRO/FLASH FLOOD HIGHLIGHTS/ADVISORIES/WARNINGS AS NEEDED. THEN...WARMER AND DRIER CONDITIONS SHOULD RETURN TO THE FORECAST DISTRICT FROM LATER THURSDAY INTO AT LEAST EARLY SUNDAY AS AN UPPER RIDGE BUILDS OVER ARIZONA AND NEW MEXICO. IN ADDITION... FORECAST PRECIPITABLE WATER VALUES DROP TO BETWEEN 0.50 AND 0.70 INCHES OVER THE INTERSTATE 25 CORRIDOR DURING THIS TIME-FRAME. GENERALLY ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS SHOULD BE NOTED OVER THE CWFA FROM LATER THURSDAY INTO EARLY SUNDAY. EVEN THOUGH RELATIVELY UNLIKELY DURING THIS TIME-FRAME...PLEASE REMEMBER THAT IF A STRONGER STORM IMPACTS A BURN SCAR...FLASH FLOODING WOULD BE POSSIBLE. IN ADDITION...STRONG TO POSSIBLY SEVERE THUNDERSTORMS MAY ALSO DEVELOP OVER PORTIONS OF THE FAR SOUTHEASTERN COLORADO PLAINS FROM THURSDAY INTO THURSDAY EVENING AS PROJECTED LOCALIZED CAPES/LIS IN EXCESS OF 2000 J/KG AND -7C RESPECTIVELY INTERACT WITH PROJECTED 0 TO 6 KM BULK SHEAR VALUES AROUND 40 KNOTS. INCREASED SHOWER AND THUNDERSTORM ACTIVITY IS THEN ANTICIPATED FROM LATER SUNDAY INTO NEXT TUESDAY AS A NORTHERLY SURFACE SURGE MOVING ACROSS EASTERN SECTIONS MONDAY INCREASES ATMOSPHERIC MOISTURE AND INTERACTS WITH UPPER SHORTWAVES. FORECAST MODEL SOUNDINGS PROJECT THAT PRECIPITABLE WATER VALUES OVER THE INTERSTATE 25 CORRIDOR INCREASE TO OVER ONE INCH BY MONDAY AFTERNOON. AT THIS TIME...IT APPEARS THAT THE HIGHEST POTENTIAL FOR LOCALIZED HEAVY RAIN AND ASSOCIATED FLASH FLOODING CONCERNS(ESPECIALLY OVER THE AREA BURN SCARS) WILL BE POSSIBLE FROM LATER SUNDAY INTO NEXT TUESDAY. AS ALWAYS...WFO PUEBLO WILL MONITOR CLOSELY. FINALLY...LOW-GRADE GRADIENT WINDS AS WELL AS ABOVE AVERAGE MID-AUGUST SEASONAL TEMPERATURES ARE ANTICIPATED OVER THE MAJORITY OF THE FORECAST DISTRICT FROM THURSDAY INTO NEXT MONDAY WITH THE WARMEST CONDITIONS EXPECTED THIS WEEKEND AS 700 MB TEMPERATURES ALONG THE I-25 CORRIDOR CLIMB TO AROUND 18C FROM THE 12C READINGS PROJECTED TODAY. MAXIMUM TEMPERATURES THIS WEEKEND OVER MANY SECTIONS OF THE SOUTHEASTERN COLORADO PLAINS SHOULD REACH WELL INTO THE 90S BOTH SATURDAY AND SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 11:15 MDT TUE AUG 13 2013 MAIN AVN CONCERN CONTINUES TO BE POTENTIAL FOR TS AT THE TAF SITES THIS AFTERNOON AND EVE...FROM 20-21Z AT KALS AND KCOS...AND 22-24Z FOR KPUB. COULD SEE SOME BRIEF HEAVY RAINFALL AND MVFR TO BRIEFLY IFR CONDITIONS IN THE HEAVIEST STORMS. ALSO SOME SMALL HAIL POSSIBLE. STORMS WILL MOVE TOT HE EAST AND SHOULD CLEAR THE TERMINALS BY SUNSET OR SHORTLY AFTER...WITH JUST SOME LINGERING SHOWERS THIS EVE. ROSE && .PUB WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 9 PM MDT THIS EVENING FOR COZ081-084-085. && $$ UPDATE...ROSE AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
845 AM MDT TUE AUG 13 2013 .UPDATE... ISSUED AT 841 AM MDT TUE AUG 13 2013 HAVE CUT BACK POPS TO ZEROS...BASED ON NEAR ZERO CLOUDS ACROSS THE CWA. WILL SEE A SLOW BUT STEADY INCREASE IN CONVECTION BY THIS AFTERNOON...FIRST ACROSS THE MTS AND THEN SPREADING EWD TO THE PLAINS. LOOKS LIKE A PRETTY TYPICAL AUG DAY. ROSE && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 528 AM MDT TUE AUG 13 2013 ...FLASH FLOOD THREAT FOR BURN SCARS IN EL PASO/TELLER COUNTIES TODAY... MOST OF SHOWER/TSTORM ACTIVITY HAS DIMINISHED ACROSS THE AREA THIS MORNING AND MODELS ARE HAVING A DIFFICULT TIME WITH THIS AS BOTH NAM12 AND GFS MAINTAIN PRECIPITATION ACROSS THE SOUTHEAST PLAINS THROUGH THE MORNING HOURS. THIS LEADS TO LOWER CONFIDENCE IN QPF FORECAST TODAY AS MODELS PLAY CATCH UP WITH WHAT IS CURRENTLY GOING ON. IN WV PICS...APPEARS MAIN SHORTWAVE WHICH HELPED FIRE OFF YESTERDAY`S CONVECTION HAS ALREADY PUSHED EAST OF THE AREA INTO CENTRAL KS. HOWEVER...ANOTHER SHORTWAVE IS EVIDENT IN THE MOISTURE PLUME ACROSS NW CO/SRN WY...WHICH WILL BE TRANSLATING SLOWLY EASTWARD THROUGH THE UPPER RIDGE ACROSS THE AREA TODAY. AT THE SFC...DEW POINTS HAVE INCREASED ACROSS THE PLAINS WITH READINGS MAINLY IN THE 50S. STRATUS IS NOT AS WIDESPREAD AS MODELS PORTRAYED...PROBABLY A RESULT OF THEIR OVERZEALOUS QPF FORECAST THIS MORNING. SUSPECT WE WILL SEE SOME STRATUS DEVELOP AND SPREAD WESTWARD INTO SOUTHEAST PLAINS TOWARDS DAWN BUT IT WILL PROBABLY BE FAIRLY SHALLOW AND MORE PATCHY IN NATURE EXCEPT ACROSS THE SE CORNER WHERE IT MAY BE MORE WIDESPREAD. THUS ANY STRATUS WILL LIKELY BURN OFF FAIRLY QUICKLY THIS MORNING. WITH MORE CLEARING THIS AFTERNOON...WE WILL BE MORE LIKELY TO SEE SUFFICIENT HEATING TO TRIGGER ANOTHER ROUND OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHEAST MOUNTAINS AND ADJACENT PLAINS. WITH LOW LEVEL FLOW REMAINING EASTERLY...DEW POINTS SHOULD REMAIN IN THE 50S ACROSS THE PLAINS/I-25 CORRIDOR. THIS WILL LEAD TO CAPE VALUES GENERALLY BETWEEN 500-1000 J/KG...NOT TERRIBLY HIGH...BUT SUFFICIENT TO PRODUCE A FEW STRONG STORMS. THUS GREATEST CONCERN WILL BE THE EL PASO/TELLER COUNTY AREAS WHERE THE SUSCEPTIBLE BURN SCARS WILL BE UNDER THE GUN FOR MORE HEAVY RAINFALL TODAY. ALTHOUGH NAM12 HAS TAMED DOWN ITS QPF FCST FOR TODAY VS YESTERDAY`S RUNS...OTHER MODELS SUCH AS GFS...HIGH RES WRF (LOCAL AND NSSL)AND HRRR BOTH HIT PORTIONS OF THE SE MTS/ADJACENT PLAINS WITH POCKETS OF HEAVY RAINFALL. WITH THE SATURATED GROUND FROM RECENT RAINS ACROSS TELLER AND EL PASO COUNTY...WILL BE PUTTING OUT ANOTHER FLASH FLOOD WATCH FOR TODAY. GREATEST THREAT WINDOW APPEARS TO BE FROM 2 PM TO 6 PM FOR THE BURN SCARS THOUGH HRRR SEEMS TO BE TRENDING IT TOWARDS 1 PM IN SOME OF ITS LATER RUNS. OF COURSE IF THE STRONGER STORMS PASS AROUND THE BURN SCARS...THEN IT IS POSSIBLE THAT FLASH FLOODING WILL NOT OCCUR...BUT WILL ERR ON THE SIDE OF CAUTION AS THE PROBABILITY WILL BE THERE FOR A HIGH IMPACT EVENT SHOULD THE BURN SCARS BE IMPACTED. THE CITY OF COLORADO SPRINGS COULD ALSO BE UNDER THE GUN TODAY FOR FLASH FLOODING DUE TO THE SATURATED GROUND FROM YESTERDAY`S HEAVY RAIN WHICH WILL EXACERBATE ANY RUNOFF TODAY SHOULD STORMS HIT THAT REGION. THUNDERSTORMS SHOULD SPREAD EASTWARD ACROSS THE PLAINS DURING THE LATE AFTERNOON AND EVENING HOURS AS THE SHORTWAVE SLOWLY KICKS THROUGH THE REGION. WILL DECREASE POPS QUICKLY AFTER 06Z AS CONSENSUS OF THE MODELS IS TO KEEP CONVECTION GOING WELL TO THE SOUTH ALONG FRONTAL BOUNDARY ACROSS EASTERN NM/SRN TX PANHANDLE. GFS SEEMS TO BE THE OUTLIER IN KEEPING WIDESPREAD QPF ACROSS THE PLAINS THROUGH 12Z...SO WILL DISCOUNT IT FOR NOW. STRATUS SHOULD BE MORE WIDESPREAD ACROSS THE SE PLAINS TONIGHT. NOT TO NEGLECT WESTERN AREAS...DRIER AIR OUT THAT WAY SHOULD KEEP PCPN EFFICIENCIES WITH THUNDERSTORMS LOWER. PRECIP WATERS WILL BE RUNNING AROUND .50 WHICH PUTS THEM BELOW 100% OF NORMAL. WITH FORCING FROM THE SHORTWAVE EXPECTED TO IMPACT NORTHERN AREAS MORE SO THAN THE SOUTHWEST...EXPECT THUNDERSTORMS TO BE MORE ISOLATED TO SCATTERED IN COVERAGE ACROSS THE EASTERN SAN JUANS AND LA GARITAS...AND WILL DIMINISH QUICKLY DURING THE EVENING HOURS. THE WEST FORK BURN SCAR WILL NEED TO BE MONITORED FROM NOON TO 6 PM FOR POCKETS OF HEAVIER RAIN SUFFICIENT TO CAUSE LOCALIZED RUNOFF/POTENTIAL FLASH FLOOD PROBLEMS. -KT .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 528 AM MDT TUE AUG 13 2013 LONGER TERM METEOROLOGICAL CONCERNS INCLUDE POPS AND TEMPERATURES. ABOVE SEASONAL POPS IN COMBINATION WITH BELOW SEASONAL TEMPERATURES ARE EXPECTED FROM WEDNESDAY INTO WEDNESDAY NIGHT AS AVAILABLE ATMOSPHERIC MOISTURE INTERACTS WITH THE DAILY OROGRAPHIC HEATING CYCLE AS WELL AS SOME UPPER LIFT. RECENT LONGER TERM FORECAST MODEL SOUNDINGS INDICATE THAT LOCATIONS SUCH AS THE I-25 CORRIDOR SHOULD EXPERIENCE PRECIPITABLE WATER VALUES NEARING ONE INCH AT TIMES WEDNESDAY AFTERNOON. THE COMBINATION OF AVAILABLE ATMOSPHERIC MOISTURE AND AN APPROACHING UPPER SHORT-WAVE(PER LATEST GFS40 PV15 FORECAST) ...ESPECIALLY OVER NORTHERN SECTIONS OF THE FORECAST DISTRICT SHOULD ALLOW FOR ANOTHER ROUND OF ISOLATED TO SCATTERED WEDNESDAY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS OVER THE FORECAST DISTRICT...ESPECIALLY EASTERN SECTIONS. ONCE AGAIN...SOME OF THESE STORMS ON WEDNESDAY AFTERNOON AND EVENING WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL AS WELL AS POTENTIAL BURN SCAR FLOODING ISSUES...ESPECIALLY IF A STRONGER STORM DEVELOPS OVER A BURN SCAR...SUCH AS THE WALDO CANYON BURN SCAR...ETC. WFO PUEBLO WILL CONTINUE TO MONITOR CLOSELY AND ISSUE HYDRO/FLASH FLOOD HIGHLIGHTS/ADVISORIES/WARNINGS AS NEEDED. THEN...WARMER AND DRIER CONDITIONS SHOULD RETURN TO THE FORECAST DISTRICT FROM LATER THURSDAY INTO AT LEAST EARLY SUNDAY AS AN UPPER RIDGE BUILDS OVER ARIZONA AND NEW MEXICO. IN ADDITION... FORECAST PRECIPITABLE WATER VALUES DROP TO BETWEEN 0.50 AND 0.70 INCHES OVER THE INTERSTATE 25 CORRIDOR DURING THIS TIME-FRAME. GENERALLY ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS SHOULD BE NOTED OVER THE CWFA FROM LATER THURSDAY INTO EARLY SUNDAY. EVEN THOUGH RELATIVELY UNLIKELY DURING THIS TIME-FRAME...PLEASE REMEMBER THAT IF A STRONGER STORM IMPACTS A BURN SCAR...FLASH FLOODING WOULD BE POSSIBLE. IN ADDITION...STRONG TO POSSIBLY SEVERE THUNDERSTORMS MAY ALSO DEVELOP OVER PORTIONS OF THE FAR SOUTHEASTERN COLORADO PLAINS FROM THURSDAY INTO THURSDAY EVENING AS PROJECTED LOCALIZED CAPES/LIS IN EXCESS OF 2000 J/KG AND -7C RESPECTIVELY INTERACT WITH PROJECTED 0 TO 6 KM BULK SHEAR VALUES AROUND 40 KNOTS. INCREASED SHOWER AND THUNDERSTORM ACTIVITY IS THEN ANTICIPATED FROM LATER SUNDAY INTO NEXT TUESDAY AS A NORTHERLY SURFACE SURGE MOVING ACROSS EASTERN SECTIONS MONDAY INCREASES ATMOSPHERIC MOISTURE AND INTERACTS WITH UPPER SHORTWAVES. FORECAST MODEL SOUNDINGS PROJECT THAT PRECIPITABLE WATER VALUES OVER THE INTERSTATE 25 CORRIDOR INCREASE TO OVER ONE INCH BY MONDAY AFTERNOON. AT THIS TIME...IT APPEARS THAT THE HIGHEST POTENTIAL FOR LOCALIZED HEAVY RAIN AND ASSOCIATED FLASH FLOODING CONCERNS(ESPECIALLY OVER THE AREA BURN SCARS) WILL BE POSSIBLE FROM LATER SUNDAY INTO NEXT TUESDAY. AS ALWAYS...WFO PUEBLO WILL MONITOR CLOSELY. FINALLY...LOW-GRADE GRADIENT WINDS AS WELL AS ABOVE AVERAGE MID-AUGUST SEASONAL TEMPERATURES ARE ANTICIPATED OVER THE MAJORITY OF THE FORECAST DISTRICT FROM THURSDAY INTO NEXT MONDAY WITH THE WARMEST CONDITIONS EXPECTED THIS WEEKEND AS 700 MB TEMPERATURES ALONG THE I-25 CORRIDOR CLIMB TO AROUND 18C FROM THE 12C READINGS PROJECTED TODAY. MAXIMUM TEMPERATURES THIS WEEKEND OVER MANY SECTIONS OF THE SOUTHEASTERN COLORADO PLAINS SHOULD REACH WELL INTO THE 90S BOTH SATURDAY AND SUNDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 528 AM MDT TUE AUG 13 2013 THERE IS THE POTENTIAL FOR SOME MVFR TO IFR CIGS TO BRIEFLY FORM OVER KCOS THIS MORNING DUE TO HEAVY RAINFALL FROM YESTERDAY AND MOIST AIRMASS. DOESN`T APPEAR TO BE A STRONG EASTERLY PUSH OF THE LOW LEVEL WINDS THOUGH TO HELP GET MORE WIDESPREAD STRATUS TO DEVELOP...SO THIS IS LIKELY TO REMAIN MORE SPOTTY IN COVERAGE AND WILL MONITOR LATEST SATELLITE TRENDS FOR THE NEED TO INCLUDE IN TAF. PLAN TO MAINTAIN SCT012 LAYER UNLESS TRENDS SUGGEST OTHERWISE. PROBABILITY FOR STRATUS LOOKS LESS LIKELY FOR KPUB BUT NOT ENTIRELY NIL. SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS THE MOUNTAINS AROUND NOON...AND MAY AFFECT THE TAF SITES AFTER 20Z. KCOS APPEARS TO HAVE THE BEST CHANCE FOR -TSRA THIS AFTERNOON. COULD SEE SOME BRIEF MVFR/IFR CIGS/VIS WITH THE STRONGER STORMS. THUNDERSTORMS THREAT SHOULD DIMINISH RAPIDLY AFTER 00Z-01Z WITH A SLIGHTLY BETTER CHANCE FOR MVFR TO IFR STRATUS TO DEVELOP ALONG THE I-25 CORRIDOR TOWARDS 12Z WED. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH THIS EVENING FOR COZ081-084-085. && $$ UPDATE...ROSE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
528 AM MDT TUE AUG 13 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 528 AM MDT TUE AUG 13 2013 ...FLASH FLOOD THREAT FOR BURN SCARS IN EL PASO/TELLER COUNTIES TODAY... MOST OF SHOWER/TSTORM ACTIVITY HAS DIMINISHED ACROSS THE AREA THIS MORNING AND MODELS ARE HAVING A DIFFICULT TIME WITH THIS AS BOTH NAM12 AND GFS MAINTAIN PRECIPITATION ACROSS THE SOUTHEAST PLAINS THROUGH THE MORNING HOURS. THIS LEADS TO LOWER CONFIDENCE IN QPF FORECAST TODAY AS MODELS PLAY CATCH UP WITH WHAT IS CURRENTLY GOING ON. IN WV PICS...APPEARS MAIN SHORTWAVE WHICH HELPED FIRE OFF YESTERDAY`S CONVECTION HAS ALREADY PUSHED EAST OF THE AREA INTO CENTRAL KS. HOWEVER...ANOTHER SHORTWAVE IS EVIDENT IN THE MOISTURE PLUME ACROSS NW CO/SRN WY...WHICH WILL BE TRANSLATING SLOWLY EASTWARD THROUGH THE UPPER RIDGE ACROSS THE AREA TODAY. AT THE SFC...DEW POINTS HAVE INCREASED ACROSS THE PLAINS WITH READINGS MAINLY IN THE 50S. STRATUS IS NOT AS WIDESPREAD AS MODELS PORTRAYED...PROBABLY A RESULT OF THEIR OVERZEALOUS QPF FORECAST THIS MORNING. SUSPECT WE WILL SEE SOME STRATUS DEVELOP AND SPREAD WESTWARD INTO SOUTHEAST PLAINS TOWARDS DAWN BUT IT WILL PROBABLY BE FAIRLY SHALLOW AND MORE PATCHY IN NATURE EXCEPT ACROSS THE SE CORNER WHERE IT MAY BE MORE WIDESPREAD. THUS ANY STRATUS WILL LIKELY BURN OFF FAIRLY QUICKLY THIS MORNING. WITH MORE CLEARING THIS AFTERNOON...WE WILL BE MORE LIKELY TO SEE SUFFICIENT HEATING TO TRIGGER ANOTHER ROUND OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHEAST MOUNTAINS AND ADJACENT PLAINS. WITH LOW LEVEL FLOW REMAINING EASTERLY...DEW POINTS SHOULD REMAIN IN THE 50S ACROSS THE PLAINS/I-25 CORRIDOR. THIS WILL LEAD TO CAPE VALUES GENERALLY BETWEEN 500-1000 J/KG...NOT TERRIBLY HIGH...BUT SUFFICIENT TO PRODUCE A FEW STRONG STORMS. THUS GREATEST CONCERN WILL BE THE EL PASO/TELLER COUNTY AREAS WHERE THE SUSCEPTIBLE BURN SCARS WILL BE UNDER THE GUN FOR MORE HEAVY RAINFALL TODAY. ALTHOUGH NAM12 HAS TAMED DOWN ITS QPF FCST FOR TODAY VS YESTERDAY`S RUNS...OTHER MODELS SUCH AS GFS...HIGH RES WRF (LOCAL AND NSSL)AND HRRR BOTH HIT PORTIONS OF THE SE MTS/ADJACENT PLAINS WITH POCKETS OF HEAVY RAINFALL. WITH THE SATURATED GROUND FROM RECENT RAINS ACROSS TELLER AND EL PASO COUNTY...WILL BE PUTTING OUT ANOTHER FLASH FLOOD WATCH FOR TODAY. GREATEST THREAT WINDOW APPEARS TO BE FROM 2 PM TO 6 PM FOR THE BURN SCARS THOUGH HRRR SEEMS TO BE TRENDING IT TOWARDS 1 PM IN SOME OF ITS LATER RUNS. OF COURSE IF THE STRONGER STORMS PASS AROUND THE BURN SCARS...THEN IT IS POSSIBLE THAT FLASH FLOODING WILL NOT OCCUR...BUT WILL ERR ON THE SIDE OF CAUTION AS THE PROBABILITY WILL BE THERE FOR A HIGH IMPACT EVENT SHOULD THE BURN SCARS BE IMPACTED. THE CITY OF COLORADO SPRINGS COULD ALSO BE UNDER THE GUN TODAY FOR FLASH FLOODING DUE TO THE SATURATED GROUND FROM YESTERDAY`S HEAVY RAIN WHICH WILL EXACERBATE ANY RUNOFF TODAY SHOULD STORMS HIT THAT REGION. THUNDERSTORMS SHOULD SPREAD EASTWARD ACROSS THE PLAINS DURING THE LATE AFTERNOON AND EVENING HOURS AS THE SHORTWAVE SLOWLY KICKS THROUGH THE REGION. WILL DECREASE POPS QUICKLY AFTER 06Z AS CONSENSUS OF THE MODELS IS TO KEEP CONVECTION GOING WELL TO THE SOUTH ALONG FRONTAL BOUNDARY ACROSS EASTERN NM/SRN TX PANHANDLE. GFS SEEMS TO BE THE OUTLIER IN KEEPING WIDESPREAD QPF ACROSS THE PLAINS THROUGH 12Z...SO WILL DISCOUNT IT FOR NOW. STRATUS SHOULD BE MORE WIDESPREAD ACROSS THE SE PLAINS TONIGHT. NOT TO NEGLECT WESTERN AREAS...DRIER AIR OUT THAT WAY SHOULD KEEP PCPN EFFICIENCIES WITH THUNDERSTORMS LOWER. PRECIP WATERS WILL BE RUNNING AROUND .50 WHICH PUTS THEM BELOW 100% OF NORMAL. WITH FORCING FROM THE SHORTWAVE EXPECTED TO IMPACT NORTHERN AREAS MORE SO THAN THE SOUTHWEST...EXPECT THUNDERSTORMS TO BE MORE ISOLATED TO SCATTERED IN COVERAGE ACROSS THE EASTERN SAN JUANS AND LA GARITAS...AND WILL DIMINISH QUICKLY DURING THE EVENING HOURS. THE WEST FORK BURN SCAR WILL NEED TO BE MONITORED FROM NOON TO 6 PM FOR POCKETS OF HEAVIER RAIN SUFFICIENT TO CAUSE LOCALIZED RUNOFF/POTENTIAL FLASH FLOOD PROBLEMS. -KT .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 528 AM MDT TUE AUG 13 2013 LONGER TERM METEOROLOGICAL CONCERNS INCLUDE POPS AND TEMPERATURES. ABOVE SEASONAL POPS IN COMBINATION WITH BELOW SEASONAL TEMPERATURES ARE EXPECTED FROM WEDNESDAY INTO WEDNESDAY NIGHT AS AVAILABLE ATMOSPHERIC MOISTURE INTERACTS WITH THE DAILY OROGRAPHIC HEATING CYCLE AS WELL AS SOME UPPER LIFT. RECENT LONGER TERM FORECAST MODEL SOUNDINGS INDICATE THAT LOCATIONS SUCH AS THE I-25 CORRIDOR SHOULD EXPERIENCE PRECIPITABLE WATER VALUES NEARING ONE INCH AT TIMES WEDNESDAY AFTERNOON. THE COMBINATION OF AVAILABLE ATMOSPHERIC MOISTURE AND AN APPROACHING UPPER SHORT-WAVE(PER LATEST GFS40 PV15 FORECAST) ...ESPECIALLY OVER NORTHERN SECTIONS OF THE FORECAST DISTRICT SHOULD ALLOW FOR ANOTHER ROUND OF ISOLATED TO SCATTERED WEDNESDAY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS OVER THE FORECAST DISTRICT...ESPECIALLY EASTERN SECTIONS. ONCE AGAIN...SOME OF THESE STORMS ON WEDNESDAY AFTERNOON AND EVENING WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL AS WELL AS POTENTIAL BURN SCAR FLOODING ISSUES...ESPECIALLY IF A STRONGER STORM DEVELOPS OVER A BURN SCAR...SUCH AS THE WALDO CANYON BURN SCAR...ETC. WFO PUEBLO WILL CONTINUE TO MONITOR CLOSELY AND ISSUE HYDRO/FLASH FLOOD HIGHLIGHTS/ADVISORIES/WARNINGS AS NEEDED. THEN...WARMER AND DRIER CONDITIONS SHOULD RETURN TO THE FORECAST DISTRICT FROM LATER THURSDAY INTO AT LEAST EARLY SUNDAY AS AN UPPER RIDGE BUILDS OVER ARIZONA AND NEW MEXICO. IN ADDITION... FORECAST PRECIPITABLE WATER VALUES DROP TO BETWEEN 0.50 AND 0.70 INCHES OVER THE INTERSTATE 25 CORRIDOR DURING THIS TIME-FRAME. GENERALLY ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS SHOULD BE NOTED OVER THE CWFA FROM LATER THURSDAY INTO EARLY SUNDAY. EVEN THOUGH RELATIVELY UNLIKELY DURING THIS TIME-FRAME...PLEASE REMEMBER THAT IF A STRONGER STORM IMPACTS A BURN SCAR...FLASH FLOODING WOULD BE POSSIBLE. IN ADDITION...STRONG TO POSSIBLY SEVERE THUNDERSTORMS MAY ALSO DEVELOP OVER PORTIONS OF THE FAR SOUTHEASTERN COLORADO PLAINS FROM THURSDAY INTO THURSDAY EVENING AS PROJECTED LOCALIZED CAPES/LIS IN EXCESS OF 2000 J/KG AND -7C RESPECTIVELY INTERACT WITH PROJECTED 0 TO 6 KM BULK SHEAR VALUES AROUND 40 KNOTS. INCREASED SHOWER AND THUNDERSTORM ACTIVITY IS THEN ANTICIPATED FROM LATER SUNDAY INTO NEXT TUESDAY AS A NORTHERLY SURFACE SURGE MOVING ACROSS EASTERN SECTIONS MONDAY INCREASES ATMOSPHERIC MOISTURE AND INTERACTS WITH UPPER SHORTWAVES. FORECAST MODEL SOUNDINGS PROJECT THAT PRECIPITABLE WATER VALUES OVER THE INTERSTATE 25 CORRIDOR INCREASE TO OVER ONE INCH BY MONDAY AFTERNOON. AT THIS TIME...IT APPEARS THAT THE HIGHEST POTENTIAL FOR LOCALIZED HEAVY RAIN AND ASSOCIATED FLASH FLOODING CONCERNS(ESPECIALLY OVER THE AREA BURN SCARS) WILL BE POSSIBLE FROM LATER SUNDAY INTO NEXT TUESDAY. AS ALWAYS...WFO PUEBLO WILL MONITOR CLOSELY. FINALLY...LOW-GRADE GRADIENT WINDS AS WELL AS ABOVE AVERAGE MID-AUGUST SEASONAL TEMPERATURES ARE ANTICIPATED OVER THE MAJORITY OF THE FORECAST DISTRICT FROM THURSDAY INTO NEXT MONDAY WITH THE WARMEST CONDITIONS EXPECTED THIS WEEKEND AS 700 MB TEMPERATURES ALONG THE I-25 CORRIDOR CLIMB TO AROUND 18C FROM THE 12C READINGS PROJECTED TODAY. MAXIMUM TEMPERATURES THIS WEEKEND OVER MANY SECTIONS OF THE SOUTHEASTERN COLORADO PLAINS SHOULD REACH WELL INTO THE 90S BOTH SATURDAY AND SUNDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 528 AM MDT TUE AUG 13 2013 THERE IS THE POTENTIAL FOR SOME MVFR TO IFR CIGS TO BRIEFLY FORM OVER KCOS THIS MORNING DUE TO HEAVY RAINFALL FROM YESTERDAY AND MOIST AIRMASS. DOESN`T APPEAR TO BE A STRONG EASTERLY PUSH OF THE LOW LEVEL WINDS THOUGH TO HELP GET MORE WIDESPREAD STRATUS TO DEVELOP...SO THIS IS LIKELY TO REMAIN MORE SPOTTY IN COVERAGE AND WILL MONITOR LATEST SATELLITE TRENDS FOR THE NEED TO INCLUDE IN TAF. PLAN TO MAINTAIN SCT012 LAYER UNLESS TRENDS SUGGEST OTHERWISE. PROBABILITY FOR STRATUS LOOKS LESS LIKELY FOR KPUB BUT NOT ENTIRELY NIL. SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS THE MOUNTAINS AROUND NOON...AND MAY AFFECT THE TAF SITES AFTER 20Z. KCOS APPEARS TO HAVE THE BEST CHANCE FOR -TSRA THIS AFTERNOON. COULD SEE SOME BRIEF MVFR/IFR CIGS/VIS WITH THE STRONGER STORMS. THUNDERSTORMS THREAT SHOULD DIMINISH RAPIDLY AFTER 00Z-01Z WITH A SLIGHTLY BETTER CHANCE FOR MVFR TO IFR STRATUS TO DEVELOP ALONG THE I-25 CORRIDOR TOWARDS 12Z WED. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH THIS EVENING FOR COZ081-084-085. && $$
AREA FORECAST DISCUSSION
NWS TAUNTON MA
347 PM EDT TUE AUG 13 2013 .SYNOPSIS... AN APPROACHING COLD FRONT WILL BRING SHOWERS AND EMBEDDED THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL THROUGH THIS EVENING. DRY AND SEASONABLE WEATHER RETURNS WEDNESDAY AND CONTINUES INTO THIS WEEKEND. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... ***SHOWERS AND EMBEDDED THUNDERSTORMS MAY BRING LOCALLY HEAVY RAINFALL/POOR DRAINAGE STREET FLOODING LATE THIS AFTERNOON*** 4 PM UPDATE...MUCH OF THE RAIN HAS DISSIPATED OR MOVED OFFSHORE IN THIS AREA. EXCEPTIONS TO THIS ARE THE CAPE AND ISLANDS WHERE STORMS ARE MOVING ACROSS NOW. THE STRONGEST OF THESE STORMS REMAIN WELL SOUTH OF SOUTHERN NEW ENGLAND AND THE OUTER COASTAL WATERS. THAT SAID...THIS HAS BEEN WELL FORECAST BY THE HRRR MODEL. THE HRRR IS ALSO ACCURATELY FORECASTING ADDITIONAL SHOWERS AND THUNDERSTORMS IN NEW YORK STATE JUST AHEAD OF THE COLD FRONT. THESE ARE FORECAST NOT TO MOVE INTO OUR AREA UNTIL CLOSE TO 00Z...AT WHICH POINT INSTABILITY IS LIKELY TO BE MORE LIMITED THAN IT ALREADY IS. HOWEVER...THERE ARE STARTING TO BE SOME INDICATIONS OF CLEARING ACROSS NEW YORK STATE AND EVEN A BIT INTO THE CONNECTICUT VALLEY IN MASS AND CONNECTICUT. IF THIS CLEARING CONTINUES...IT MAY PRODUCE ENOUGH INSTABILITY TO SUSTAIN THESE STORMS. IF THE STORMS SUSTAIN THEMSELVES...THERE IS POTENTIAL FOR LOCALLY HEAVY RAINFALL AND POSSIBLY URBAN AND POOR DRAINAGE FLOODING. IN ADDITION...THE ENVIRONMENT IS THE SAME HIGH SHEAR...LOW CAPE ENVIRONMENT WE HAVE BEEN IN MUCH OF THE SUMMER. THEREFORE...THERE IS A POTENTIAL FOR STRONG WINDS WITH THE STRONGEST STORMS. && .SHORT TERM /10 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... TONIGHT...LINGERING SHOWERS SHOULD COME TO AN END SHORTLY AFTER MIDNIGHT IF NOT BEFORE. THEN CLEARING FROM WEST TO EAST AS THE COLD FRONT MOVES THROUGH AND DRIER AIR STARTS MOVING IN. TEMPERATURES OVERNIGHT WILL REMAIN FAIRLY MILD WHILE THE DRY AIR MOVES IN. WEDNESDAY AND WEDNESDAY NIGHT...HIGH PRESSURE STARTS BUILDING INTO THE REGION. A REASONABLY STRONG LOW LEVEL JET AND DECENT MIXING WILL RESULT IN GUSTY WINDS DURING THE DAY WHICH WILL PRECLUDE SEA BREEZES FROM DEVELOPING. OTHERWISE...QUIET WEATHER EXPECTED WITH BELOW NORMAL TEMPERATURES MORE REMINISCENT OF SEPTEMBER THAN OF MID AUGUST. && .LONG TERM /THURSDAY THROUGH TUESDAY/... HIGHLIGHTS... * QUIET...SEASONABLE WEATHER THROUGH THIS WEEKEND * POSSIBILITY OF SOME RAIN EARLY NEXT WEEK OVERVIEW AND MODEL PREFERENCES... 13/12Z GUIDANCE CONTINUES TO DECENT OVERALL SYNOPTIC AGREEMENT THROUGH MUCH OF THIS PERIOD. 13/00Z LONG RANGE GUIDANCE CONTINUES TO SHOW QUITE GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. INITIAL WEAK MID-LEVEL CUTOFF IS PROGGED TO MOVE INTO THE CANADIAN MARITIMES...WITH ANOTHER MID- LEVEL CUTOFF MOVING FROM HUDSON BAY TO SOUTHEAST CANADA TOWARD THE END OF THIS WEEK. THIS SETS UP A PATTERN WITH A BROAD MID- LEVEL TROUGH OVER SOUTHEAST CANADA...WITH A WEAKER SOUTHERN BRANCH OF THE JET STREAM CONVERGING NEAR THE MARITIMES. THE END RESULT SHOULD BE PERSISTENT RIDGING NEAR OR OVER SOUTHERN NEW ENGLAND THROUGH MUCH OF THE EXTENDED FORECAST. STAYED CLOSE TO THE CONSENSUS SOLUTION...UNTIL SOME OF THE FINER DETAILS CAN BE BETTER RESOLVED. THURSDAY INTO AS A SECOND CUTOFF DIVES S FROM HUDSON BAY IN THE PERSISTENT BROAD TROF OVER ERN CANADA AND THE NORTHEAST CONUS. HOWEVER...THE LONGWAVE TROF AND THIS SECOND CUTOFF LOOK TO HAVE LITTLE EFFECT ON THE REGION AS STRONG RIDGING ALONG THE SOUTHERN HALF OF THE CONUS COMBINES WITH RIDGING IN THE ATLANTIC TO YIELD SUBSIDENCE AND BROAD SFC HIGH PRES OVER THE NORTHEAST. GIVEN THERE IS GOOD AGREEMENT BETWEEN BOTH OPERATIONAL MODELS AND THEIR COUNTERPART ENSEMBLES...HAVE REASONABLY HIGH CONFIDENCE THAT THIS HIGH PRES WILL YIELD A MOSTLY DRY FORECAST THROUGH EARLY NEXT WEEK. GIVEN THIS...WILL USE A GFS/ECMWF BLEND AS A BASELINE FOR THIS FORECAST UPDATE. TEMPERATURES SHOULD SLOWLY RISE THROUGH THIS PORTION OF THE FORECAST...BUT REMAIN SEASONABLE. COMFORTABLE HUMIDITY LEVELS THROUGH FRIDAY...WILL SLOWLY INCREASE THIS WEEKEND INTO EARLY NEXT WEEK. THERE IS SOME QUESTION AS TO HOW CLOSE A LOW PRESSURE WILL GET TO OUR REGION EARLY NEXT WEEK. AT THIS JUNCTURE...THINKING IT WILL REMAIN WELL TO OUR SOUTH...SO KEPT THE FORECAST DRY. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE CONFIDENCE TODAY AND TONIGHT. HIGH CONFIDENCE WEDNESDAY AND WEDNESDAY NIGHT. THROUGH 00Z...RAIN WITH EMBEDDED THUNDERSTORMS ALONG SOUTH COAST...CAPE...AND ISLANDS. ISOLD TO SCT SHRA ELSEWHERE. GENERALLY IFR IN THE MAIN BATCH OF RAIN WITH IFR TO VFR CONDITIONS ELSEWHERE. IFR CONDITIONS WILL BE MOSTLY DUE TO POCKETS OF HEAVIER RAIN. EXACT TIMING REMAINS UNCERTAIN. TONIGHT...LOW PROBABILITY OF A LINE OF SHOWERS AND THUNDERSTORMS MOVING INTO WESTERN ZONES RIGHT AROUND 00Z. OTHERWISE...MAY SEE SOME LINGERING LOW CLOUDS AND FOG PATCHES PERSIST AT SOME /ESPECIALLY EASTERN/ TERMINALS INTO THE OVERNIGHT HOURS. AREAL COVERAGE OF LOW CLOUDS AND FOG PATCHES ARE UNCERTAIN. WEDNESDAY...ANY LEFTOVER MVFR-IFR CONDITIONS IN SCATTERED LOW CLOUDS/FOG PATCHES WILL IMPROVE TO VFR NOT LONG AFTER SUNRISE. OTHERWISE...VFR CONDITIONS. WEDNESDAY NIGHT...VFR. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING. MAY SEE BOUNCING BETWEEN VFR AND LOWER CATEGORIES WITH RAIN THIS EVENING. KBDL TERMINAL...MODERATE CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING. OUTLOOK...THURSDAY THROUGH SUNDAY... HIGH CONFIDENCE VFR. LOW CONFIDENCE FOR IFR IN PATCHY FOG AND LOW CLOUDS LATE THURSDAY NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHERN WATERS THIS AFTERNOON WITH ANOTHER ROUND OF ISOLATED TO SCATTERED STORMS LATE THIS EVENING. THESE STORMS WILL LIMIT VISIBILITIES. EXPECT CLEARING LATE TONIGHT WITH FAIRLY QUIET WEATHER WEDNESDAY AND WEDNESDAY NIGHT. THERE IS POTENTIAL FOR 5 FOOT SEAS AND WESTERLY WINDS GUSTING TO 25 KTS ON THE OUTER WATERS. WITH THE NICE BOATING WEATHER EXPECTED...HAVE ISSUED A SMALL CRAFT ADVISORY FOR THE OUTER WATERS FOR WEDNESDAY AND WEDNESDAY NIGHT. OUTLOOK...THURSDAY THROUGH SUNDAY... HIGH CONFIDENCE. QUIET BOATING WEATHER EXPECTED. WINDS WILL SHIFT DIRECTION AS A HIGH PRESSURE BUILDS OVER SOUTHERN NEW ENGLAND AND THE WATERS BUT WILL REMAIN BELOW 20 KTS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON WEDNESDAY TO 5 AM EDT THURSDAY FOR ANZ250-254>256. && $$ SYNOPSIS...RLG/BELK NEAR TERM...RLG SHORT TERM...RLG LONG TERM...BELK AVIATION...RLG/BELK MARINE...RLG/BELK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
203 PM EDT TUE AUG 13 2013 .SYNOPSIS... AN APPROACHING COLD FRONT WILL BRING SHOWERS AND EMBEDDED THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL THROUGH THIS EVENING. DRY AND SEASONABLE WEATHER RETURNS WEDNESDAY AND CONTINUES INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... ***SHOWERS AND EMBEDDED THUNDERSTORMS MAY BRING LOCALLY HEAVY RAINFALL/POOR DRAINAGE STREET FLOODING LATE THIS AFTERNOON*** 2 PM UPDATE...MUCH OF THE RAIN HAS DISSIPATED OR MOVED OFFSHORE IN THIS AREA. EXCEPTIONS TO THIS ARE SOUTHERN RHODE ISLAND AND SOUTHEASTERN MASSACHUSETTS INCLUDING THE CAPE AND ISLANDS WHERE STORMS MOVING NORTHEASTWARD FROM NEW JERSEY ARE TRACKING. THE STRONGEST OF THESE STORMS REMAIN WELL SOUTH OF SOUTHERN NEW ENGLAND...POSSIBLY ONLY CLIPPING THE SOUTHERN OUTER COASTAL WATERS. THAT SAID...THIS IS VERY SIMILAR TO THE HRRR MODEL THAT FORECASTS ADDITIONAL SHOWERS AND THUNDERSTORMS FORMING IN NEW YORK STATE JUST AHEAD OF THE COLD FRONT. THESE STORMS HAVE DEVELOPED JUST EAST OF LAKE ONTARIO SOUTHWARD INTO CENTRAL PENNSYLVANIA AND WILL SLOWLY MAKE THEIR WAY EASTWARD. THESE ARE FORECAST NOT TO MOVE INTO OUR AREA UNTIL CLOSE TO 00Z...AT WHICH POINT INSTABILITY IS LIKELY TO BE MORE LIMITED THAN IT ALREADY IS. HOWEVER...THERE ARE STARTING TO BE SOME INDICATIONS OF CLEARING ACROSS NEW YORK STATE AND EVEN A BIT INTO THE CONNECTICUT VALLEY IN MASS AND CONNECTICUT. IF THIS CLEARING CONTINUES...IT MAY PRODUCE ENOUGH INSTABILITY TO SUSTAIN THESE STORMS. IF THE STORMS SUSTAIN THEMSELVES...THERE IS GOOD POTENTIAL FOR LOCALLY HEAVY RAINFALL AND POSSIBLY URBAN AND POOR DRAINAGE FLOODING. IN ADDITION...THE ENVIRONMENT IS THE SAME HIGH SHEAR...LOW CAPE ENVIRONMENT WE HAVE BEEN IN MUCH OF THE SUMMER. THEREFORE...THERE IS A POTENTIAL FOR STRONG WINDS WITH THE STRONGEST STORMS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... TONIGHT... A FEW SHOWERS AND ISOLATED THUNDERSTORMS MAY LINGER DURING THE EVENING ESPECIALLY ALONG THE COAST. OTHERWISE...MUCH DRIER MID LEVEL AIR WILL WORK INTO THE REGION BY LATE EVENING BRINGING AN END TO MOST OF THE PRECIPITATION. MAY SEE SOME PATCHY GROUND FOG DEVELOP IN THE TYPICALLY PRONE LOCATIONS...ESPECIALLY IN AREAS THAT SEE A FAIR AMOUNT OF RAIN TODAY. LOW TEMPS WILL MAINLY BE IN THE UPPER 50S AND LOWER 60S. WEDNESDAY... A MIXTURE OF CLOUDS/SUN ALONG WITH GUSTY NORTHWEST WINDS BEHIND THE COLD FRONT ON WED. LOW RISK OF A BRIEF SPRINKLE/SPOT SHOWER ACROSS OUR FAR NORTHWEST ZONES...BUT BASICALLY A DRY AND BEAUTIFUL DAY EXPECTED FOR THE MIDDLE OF AUGUST. HIGH TEMPS WILL MAINLY BE IN THE 70S WITH LOW HUMIDITY. IN FACT...SOME OF THE HIGHEST TERRAIN WILL STRUGGLE TO REACH 70! && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... HIGHLIGHTS... * QUIET...SEASONABLE WEATHER WED THRU THE WEEKEND * POSSIBILITY OF SOME RAIN EARLY NEXT WEEK OVERVIEW AND MODEL PREFERENCES... 13/00Z LONG RANGE GUIDANCE CONTINUES TO SHOW QUITE GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. INITIAL WEAK CUTOFF IS PROGGED TO SLIDE INTO THE CANADIAN MARITIMES AS A SECOND CUTOFF DIVES S FROM HUDSON BAY IN THE PERSISTENT BROAD TROF OVER ERN CANADA AND THE NORTHEAST CONUS. HOWEVER...THE LONGWAVE TROF AND THIS SECOND CUTOFF LOOK TO HAVE LITTLE EFFECT ON THE REGION AS STRONG RIDGING ALONG THE SOUTHERN HALF OF THE CONUS COMBINES WITH RIDGING IN THE ATLANTIC TO YIELD SUBSIDENCE AND BROAD SFC HIGH PRES OVER THE NORTHEAST. GIVEN THERE IS GOOD AGREEMENT BETWEEN BOTH OPERATIONAL MODELS AND THEIR COUNTERPART ENSEMBLES...HAVE REASONABLY HIGH CONFIDENCE THAT THIS HIGH PRES WILL YIELD A MOSTLY DRY FORECAST THROUGH EARLY NEXT WEEK. GIVEN THIS...WILL USE A GFS/ECWMF BLEND AS A BASELINE FOR THIS FORECAST UPDATE. WED NIGHT INTO FRI... HIGH PRES GRADUALLY SLIDES IN FROM THE W THROUGH THE PERIOD. WITH THE HIGH PRES CENTER REMAINING W OF THE REGION...EXPECT US TO REMAIN ON THE COOLER SIDE OF THE HIGH INITIALLY. H85 TEMPS RANGE BETWEEN +8C AND ABOUT +11C...SO HIGHS SHOULD START THU AROUND THE MID 70S...INCREASING TO THE UPPER 70S AND LOW 80S BY FRI AFTER SOME AIRMASS MODIFICATION. OVERNIGHT MINS WILL BE ON THE COOL SIDE WITH LOW HUMIDITY /AND THEREFORE LOW DWPTS/ WITH LIGHT FLOW AND CLEAR SKIES. EXPECTING MINS DIPPING AS LOW AS THE MID 40S IN NORMALLY COOLER SPOTS. MID 50S IN THE WARMER SPOTS. THIS COMING WEEKEND... A WARM FRONT IS EXPECTED TO BEGIN A GRADUAL SLIDE TO THE N THROUGH THE WEEKEND...BUT WITH HIGH PRES IN PLACE OVER THE REGION AND VERY SLOWLY SLIDING TO THE E...EXPECTING MOSTLY DRY CONDITIONS ACROSS SRN NEW ENGLAND DESPITE THIS APPROACHING FRONT. GFS CURRENTLY SUGGESTS HIGHEST POTENTIAL FOR SOME PRECIP...BUT IT TOO KEEPS MOST OF ITS GENERATED QPF TO THE W. MID LVL TEMPS DO INCREASE SOMEWHAT...REACHING +10 TO +13C...SO TEMPS LEAN NEAR TO SLIGHTLY WARMER THAN NORMAL. EARLY NEXT WEEK... DIFFERENCES IN THE TIMING OF A STRONGER SHORTWAVE EFFECTING THE REGION GIVES WAY TO LOWER CONFIDENCE HERE...BUT IT APPEARS THAT THERE WILL BE A BIT HIGHER CHANCE FOR SOME PRECIP PARTICULARLY BY TUE. WILL BE INCREASING TO SOME SLIGHT CHANCE POPS...CLOSER TO THE ECWMF SOLUTION...WHICH SUGGESTS THE WARM FRONT LIFTS FAR ENOUGH N TO AFFECT THE REGION WITH THIS SHORTWAVE PASSAGE. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE CONFIDENCE TODAY AND TONIGHT. HIGH CONFIDENCE WEDNESDAY AND WEDNESDAY NIGHT. THROUGH 00Z...RAIN WITH EMBEDDED THUNDERSTORMS ALONG SOUTH COAST...CAPE...AND ISLANDS. ISOLD TO SCT SHRA ELSEWHERE. GENERALLY IFR IN THE MAIN BATCH OF RAIN WITH IFR TO VFR CONDITIONS ELSEWHERE. IFR CONDITIONS WILL BE MOSTLY DUE TO POCKETS OF HEAVIER RAIN. EXACT TIMING REMAINS UNCERTAIN. TONIGHT...LOW PROBABILITY OF A LINE OF SHOWERS AND THUNDERSTORMS MOVING INTO WESTERN ZONES RIGHT AROUND 00Z. OTHERWISE...MAY SEE SOME LINGERING LOW CLOUDS AND FOG PATCHES PERSIST AT SOME /ESPECIALLY EASTERN/ TERMINALS INTO THE OVERNIGHT HOURS. AREAL COVERAGE OF LOW CLOUDS AND FOG PATCHES ARE UNCERTAIN. WEDNESDAY...ANY LEFTOVER MVFR-IFR CONDITIONS IN SCATTERED LOW CLOUDS/FOG PATCHES WILL IMPROVE TO VFR NOT LONG AFTER SUNRISE. OTHERWISE...VFR CONDITIONS. WEDNESDAY NIGHT...VFR. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING. MAY SEE BOUNCING BETWEEN VFR AND LOWER CATEGORIES WITH RAIN THIS EVENING. KBDL TERMINAL...MODERATE CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING. OUTLOOK...THURSDAY THROUGH SATURDAY... HIGH CONFIDENCE. VFR. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY AND TONIGHT...HIGH CONFIDENCE. WINDS AND SEAS WILL REMAIN BELOW SCA THRESHOLDS WITH A RELATIVELY WEAK PRESSURE GRADIENT IN PLACE. THE MAIN CONCERN EARLY THIS MORNING WILL BE FOR DENSE FOG ACROSS OUR SOUTHERN WATERS. THIS FOG SHOULD BURN OFF TO AT LEAST SOME DEGREE BY MID TO LATE MORNING. THE OTHER CONCERN WILL BE FOR EMBEDDED THUNDERSTORMS TO WORK ACROSS THE WATERS...MAINLY THIS AFTERNOON AND EVENING. WEDNESDAY...MODERATE CONFIDENCE. NORTHWEST WIND GUSTS OF 25 KNOTS ARE EXPECTED NEAR SHORE WITH GOOD MIXING BEHIND THE COLD FRONT. ITS 3RD PERIOD SO DID NOT GO WITH ANY HEADLINES AT THIS POINT...BUT LATER SHIFTS MAY NEED TO CONSIDER A SCA FOR SOME OF OUR NEAR SHORE WATERS. MAY ALSO SEE SOME 3 TO 5 FOOT SEAS DEVELOP ACROSS OUR SOUTHERN MOST ATLANTIC WATERS...WHICH MAY ALSO NEED TO BE CONSIDERED FOR HEADLINES. OUTLOOK...WEDNESDAY THROUGH SATURDAY... HIGH CONFIDENCE. QUIET BOATING WEATHER EXPECTED. WINDS WILL SHIFT DIRECTION AS HIGH PRESSURE BUILDS OVER SOUTHERN NEW ENGLAND AND THE WATERS BUT WILL REMAIN BELOW 25 KTS...SAVE FOR POSSIBLY WED EVENING. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...FRANK/DOODY NEAR TERM...FRANK/DOODY/RLG SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY/RLG MARINE...FRANK/DOODY
AREA FORECAST DISCUSSION
NWS ALBANY NY
145 PM EDT TUE AUG 13 2013 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE REGION THIS AFTERNOON WITH ADDITIONAL SHOWERS AND PERHAPS A THUNDERSTORM. IN ITS WAKE...COOLER AND LESS HUMID AIR WILL RETURN TO THE REGION FOR TOMORROW. THROUGH THE REMAINDER OF THE WEEK...HIGH PRESSURE WILL ALLOW FOR DRY CONDITIONS...WITH TEMPERATURES SLOWLY MODERATING BACK TOWARDS NORMAL LEVELS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM EDT...WE HAD A PRETTY HEAVY BATCH OF RAIN (WITH EMBEDDED THUNDERSTORMS) MOVE THROUGH PORTIONS OF THE REGION...WITH THE HEAVIEST RAINFALL FALLING TO THE EAST OF THE CAPITAL DISTRICT WHERE RAINFALL ESTIMATED APPROACHING TWO INCHES. PLEASE REFER TO OUR LATEST PUBLIC WEATHER STATEMENTS (PNS) FOR ALL THE LATEST RAINFALL REPORTS. THIS BATCH OF RAIN HAS MOSTLY MOVED TO THE EAST OF THE HUDSON VALLEY..WITH SOME POCKETS OF MODERATE TO HEAVY RAINFALL IN DUTCHESS COUNTY AS WELL AS PORTIONS OF SOUTHERN VERMONT. THERE WERE WIDELY SCATTERED LIGHT SHOWERS STILL AROUND MAINLY ACROSS THE MOHAWK VALLEY. HOWEVER...ANOTHER LINE OF SHOWERS WERE DEVELOPING RIGHT AHEAD OF THE COLD FRONT...LOCATED IN CENTRAL NEW YORK. THE HRRR AND HIRESWRF BOTH HAVE THIS LINE OF SHOWERS COMING THROUGH. FOR ONCE...THESE MODELS HAVE APPEARED TO DONE FAIRLY WELL WITH THE EVOLUTION OF THE RAINFALL THUS FAR. THEREFORE...WILL LEAN WITH ITS SOLUTION OF BRINGING ANOTHER LINE OF NUMEROUS SHOWERS OUR WAY THIS AFTERNOON. THIS LINE LOOKS TO MOVE THROUGH BETWEEN ABOUT 100 PM (NORTHWEST) TO ABOUT 800 PM (SOUTHEAST). WINDS OFF THE DECK LOOK TO BACK TO THE SOUTHEAST WILL WOULD HELP ENHANCED CONVERGENCE AND UPWARD MOTION WITH THE FRONT. INSTABILITY IS VERY LIMITED...GENERALLY UNDER 1000/J SO AT THIS TIME...WE ARE FAIRLY CONFIDENT THERE WILL BE NO SEVERE OR EVEN STRONG THUNDERSTORM ACTIVITY. ONE THING TO NOTE...THERE IS SOME PRETTY LOW LEVEL WIND WITH THE LOWER WINDS SSE BECOMING WSW QUICKLY AS ONE GOES THROUGH NEAR THE GROUND THROUGH ABOUT 5000 FEET. THERE COULD BE SOME WEAK LOW LEVEL ROTATION BUT AGAIN WITH VERY LIMITED INSTABILITY NOTHING ELSE IS EXPECTED...OTHER THAN PERHAPS A LITTLE MORE HEAVY RAINFALL. MAX TEMPS LOOK TO BE THE HELD IN THE LOW TO MID 70S TODAY. TEMPS WILL ONLY REACH THE UPPER 60S ACROSS THE HIGHEST TERRAIN. THE FRONT WILL CROSS DURING THE EARLY EVENING HOURS. THIS WILL BRING AN END TO THE RAIN SHOWERS. SOME LINGERING SHOWERS ARE POSSIBLE ACROSS NORTHERN AREAS TONIGHT AS THE UPPER TROUGH APPROACHES AND PASSES JUST TO THE NORTH. WITH COOLER AIR STARTING TO MOVE IN BEHIND THE COLD FRONT...MIN TEMPS WILL DROP INTO THE 50S OVERNIGHT AND DEWPOINTS WILL FALL DURING THE OVERNIGHT HOURS. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE OHIO VALLEY FOR THE ENTIRE SHORT TERM PERIOD. IT LOOKS TO BE MAINLY DRY ACROSS THE REGION WITH COMFORTABLE HUMIDITY LEVELS AND BELOW NORMAL TEMPERATURES. THE EXCEPTION TO THE DRY WEATHER WILL BE DURING THE DAY ON WEDNESDAY ACROSS THE ADKS...WHERE COOL TEMPS ALOFT WILL ALLOW FOR THE FORMATION OF SOME SCATTERED LIGHT RAIN SHOWERS. MAX TEMPS ON WED AND THURSDAY WILL BE IN THE LOW TO MID 70S FOR VALLEY AREAS /60 ACROSS THE HIGH TERRAIN. MIN TEMPS WILL GENERALLY BE IN THE LOW 50S /40S FOR THE HIGH TERRAIN AND OUTLYING AREAS/. && .LONG TERM /FRIDAY THROUGH MONDAY/... DRY AND TRANQUIL WEATHER IS EXPECTED FOR THE PERIOD. RIDGING IS EXPECTED TO DOMINATE AT THE SURFACE WITH HEIGHTS ALOFT GRADUALLY RISING WITH RIDGING BUILDING IN ACROSS THE WESTERN ATLANTIC. A WAVE OF LOW PRESSURE IS EXPECTED TO MOVE EASTWARD ALONG A STALLED FRONTAL BOUNDARY ACROSS THE SOUTHEASTERN UNITED STATES. THE BOUNDARY IS EXPECTED TO SHIFT NORTHWARD OVER THE WEEKEND. HOWEVER IT APPEARS PRECIPITATION ASSOCIATED WITH THIS FEATURE SHOULD REMAIN TO OUR SOUTH...SO LOOKING AT DRY WEATHER THROUGH THE WEEKEND INTO EARLY NEXT WEEK. SEASONABLE TEMPERATURES ARE EXPECTED WITH HIGHS MAINLY IN THE MID 70S TO LOWER 80S. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... MOST OF THE RAIN HAS MOVED EAST OF THE TAF SITES. STILL SOME PATCHES OF LIGHT RAIN...ONE OVER KGFL AND ONE OVER KPOU. CONDITIONS SHOULD GRADUALLY IMPROVE OVER THE NEXT COUPLE OF HOURS BEFORE ANOTHER ROUND OF SHOWERS AND POSSIBLY A THUNDERSTORM ARRIVE AHEAD OF THE COLD FRONT. DO NOT HAVE THUNDERSTORMS SPECIFICALLY MENTIONED IN TAFS AT TIME. NOT MANY LIGHTNING STIKES UPSTREAM. LATER SHIFTS WILL MONITOR AND AMEND AS NECESSARY. CONDITIONS SHOULD IMPROVE TO VFR FOR A PERIOD THIS EVENING INTO THE OVERNIGHT...HOWEVER A RETURN TO MVFR IS ANTICIPATED WITH IFR POSSIBLE AT KGFL AND KPSF. LIGHT SOUTHERLY WINDS WILL SHIFT TO THE WEST AND NORTHWEST WITH THE PASSAGE OF THE COLD FRONT THIS EVENING. WINDS WILL BE STRONG AND GUSTY FROM THE NORTHWEST ON WEDNESDAY...GUSTING TO 25 KNOTS. OUTLOOK... WED-SAT: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... NO FIRE WX ISSUES EXPECTED OVER THE NEXT FEW DAYS. SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A FRONTAL BOUNDARY IS EXPECTED TODAY. RAINFALL AMOUNTS LOOK TO AVERAGE AROUND ONE HALF INCH...LOCALLY OVER AN INCH WHERE HEAVIER SHOWERS OR THUNDERSTORMS TAKE PLACE. THIS WILL BRING A WETTING RAIN TO THE REGION. RH VALUES WILL ONLY DROP TO 70 TO 80 PERCENT TODAY DUE TO CLOUDS AND RAIN. THEY WILL BE NEAR 100 PERCENT TONIGHT AND DROP TO AROUND 40 TO 60 PERCENT TOMORROW AFTERNOON. LARGE CANADIAN HIGH PRESSURE LOOKS TO TAKE CONTROL OF OUR WEATHER WEDNESDAY THROUGH AT LEAST FRIDAY WITH DRY WEATHER. && .HYDROLOGY... AN APPROACHING FRONTAL BOUNDARY WILL BRING A ROUND OF RAIN SHOWERS AND POSSIBLE THUNDERSTORMS TO THE REGION TODAY. PWAT VALUES WILL RISE TO AROUND 1.50-1.75 INCHES INCHES AHEAD OF THE FRONTAL BOUNDARY. WHILE ANY SHOWER OR THUNDERSTORM WILL BE CAPABLE OF HEAVY DOWNPOURS...THE ATMOSPHERE IS NOT QUITE AS MOIST AS LATE LAST WEEK WHEN SOME FLASH FLOODING OCCURRED ACROSS THE MID HUDSON VALLEY AND NW CT. IN ADDITION...STRONG FLOW ALOFT SHOULD KEEP ANY SHOWERS OR THUNDERSTORMS MOVING RATHER QUICKLY. AS A RESULT...FLASH FLOODING IS NOT ANTICIPATED WITH THIS STORM SYSTEM. SOME MINOR RISES WILL BE POSSIBLE ON AREA RIVERS AND STREAMS...ESPECIALLY ACROSS THOSE AREAS THAT SAW HEAVIER RAIN LAST WEEK. THERE STILL COULD BE PONDING ON ROADWAYS AND AREAS OF POOR DRAINAGE THROUGH TUESDAY EVENING. DRY WEATHER WILL RETURN BY LATE TONIGHT AND CONTINUE THROUGH THE REMAINDER OF THE WEEK. THIS WILL ALLOW RIVER AND STREAMS LEVELS TO RECEDE ONCE MORE. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...FRUGIS/HWJIV NEAR TERM...SND/HWJIV SHORT TERM...FRUGIS LONG TERM...IAA AVIATION...SND FIRE WEATHER...FRUGIS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1230 PM EDT TUE AUG 13 2013 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE REGION THIS AFTERNOON WITH ADDITIONAL SHOWERS AND PERHAPS A THUNDERSTORM. IN ITS WAKE...COOLER AND LESS HUMID AIR WILL RETURN TO THE REGION FOR TOMORROW. THROUGH THE REMAINDER OF THE WEEK...HIGH PRESSURE WILL ALLOW FOR DRY CONDITIONS...WITH TEMPERATURES SLOWLY MODERATING BACK TOWARDS NORMAL LEVELS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM EDT...WE HAD A PRETTY HEAVY BATCH OF RAIN (WITH EMBEDDED THUNDERSTORMS) MOVE THROUGH PORTIONS OF THE REGION...WITH THE HEAVIEST RAINFALL FALLING TO THE EAST OF THE CAPITAL DISTRICT WHERE RAINFALL ESTIMATED APPROACHING TWO INCHES. PLEASE REFER TO OUR LATEST PUBLIC WEATHER STATEMENTS (PNS) FOR ALL THE LATEST RAINFALL REPORTS. THIS BATCH OF RAIN HAS MOSTLY MOVED TO THE EAST OF THE HUDSON VALLEY..WITH SOME POCKETS OF MODERATE TO HEAVY RAINFALL IN DUTCHESS COUNTY AS WELL AS PORTIONS OF SOUTHERN VERMONT. THERE WERE WIDELY SCATTERED LIGHT SHOWERS STILL AROUND MAINLY ACROSS THE MOHAWK VALLEY. HOWEVER...ANOTHER LINE OF SHOWERS WERE DEVELOPING RIGHT AHEAD OF THE COLD FRONT...LOCATED IN CENTRAL NEW YORK. THE HRRR AND HIRESWRF BOTH HAVE THIS LINE OF SHOWERS COMING THROUGH. FOR ONCE...THESE MODELS HAVE APPEARED TO DONE FAIRLY WELL WITH THE EVOLUTION OF THE RAINFALL THUS FAR. THEREFORE...WILL LEAN WITH ITS SOLUTION OF BRINGING ANOTHER LINE OF NUMEROUS SHOWERS OUR WAY THIS AFTERNOON. THIS LINE LOOKS TO MOVE THROUGH BETWEEN ABOUT 100 PM (NORTHWEST) TO ABOUT 800 PM (SOUTHEAST). WINDS OFF THE DECK LOOK TO BACK TO THE SOUTHEAST WILL WOULD HELP ENHANCED CONVERGENCE AND UPWARD MOTION WITH THE FRONT. INSTABILITY IS VERY LIMITED...GENERALLY UNDER 1000/J SO AT THIS TIME...WE ARE FAIRLY CONFIDENT THERE WILL BE NO SEVERE OR EVEN STRONG THUNDERSTORM ACTIVITY. ONE THING TO NOTE...THERE IS SOME PRETTY LOW LEVEL WIND WITH THE LOWER WINDS SSE BECOMING WSW QUICKLY AS ONE GOES THROUGH NEAR THE GROUND THROUGH ABOUT 5000 FEET. THERE COULD BE SOME WEAK LOW LEVEL ROTATION BUT AGAIN WITH VERY LIMITED INSTABILITY NOTHING ELSE IS EXPECTED...OTHER THAN PERHAPS A LITTLE MORE HEAVY RAINFALL. MAX TEMPS LOOK TO BE THE HELD IN THE LOW TO MID 70S TODAY. TEMPS WILL ONLY REACH THE UPPER 60S ACROSS THE HIGHEST TERRAIN. THE FRONT WILL CROSS DURING THE EARLY EVENING HOURS. THIS WILL BRING AN END TO THE RAIN SHOWERS. SOME LINGERING SHOWERS ARE POSSIBLE ACROSS NORTHERN AREAS TONIGHT AS THE UPPER TROUGH APPROACHES AND PASSES JUST TO THE NORTH. WITH COOLER AIR STARTING TO MOVE IN BEHIND THE COLD FRONT...MIN TEMPS WILL DROP INTO THE 50S OVERNIGHT AND DEWPOINTS WILL FALL DURING THE OVERNIGHT HOURS. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE OHIO VALLEY FOR THE ENTIRE SHORT TERM PERIOD. IT LOOKS TO BE MAINLY DRY ACROSS THE REGION WITH COMFORTABLE HUMIDITY LEVELS AND BELOW NORMAL TEMPERATURES. THE EXCEPTION TO THE DRY WEATHER WILL BE DURING THE DAY ON WEDNESDAY ACROSS THE ADKS...WHERE COOL TEMPS ALOFT WILL ALLOW FOR THE FORMATION OF SOME SCATTERED LIGHT RAIN SHOWERS. MAX TEMPS ON WED AND THURSDAY WILL BE IN THE LOW TO MID 70S FOR VALLEY AREAS /60 ACROSS THE HIGH TERRAIN. MIN TEMPS WILL GENERALLY BE IN THE LOW 50S /40S FOR THE HIGH TERRAIN AND OUTLYING AREAS/. && .LONG TERM /FRIDAY THROUGH MONDAY/... DRY AND TRANQUIL WEATHER IS EXPECTED FOR THE PERIOD. RIDGING IS EXPECTED TO DOMINATE AT THE SURFACE WITH HEIGHTS ALOFT GRADUALLY RISING WITH RIDGING BUILDING IN ACROSS THE WESTERN ATLANTIC. A WAVE OF LOW PRESSURE IS EXPECTED TO MOVE EASTWARD ALONG A STALLED FRONTAL BOUNDARY ACROSS THE SOUTHEASTERN UNITED STATES. THE BOUNDARY IS EXPECTED TO SHIFT NORTHWARD OVER THE WEEKEND. HOWEVER IT APPEARS PRECIPITATION ASSOCIATED WITH THIS FEATURE SHOULD REMAIN TO OUR SOUTH...SO LOOKING AT DRY WEATHER THROUGH THE WEEKEND INTO EARLY NEXT WEEK. SEASONABLE TEMPERATURES ARE EXPECTED WITH HIGHS MAINLY IN THE MID 70S TO LOWER 80S. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... SHOWERS AND SCATTERED THUNDERSTORMS WILL CONTINUE TO OVERSPREAD THE AREA THIS MORNING WITH MVFR CONDITIONS DEVELOPING. DYNAMICS WITH THIS SYSTEM ARE STRONG ENOUGH THAT AN AREA OF LOW PRESSURE HAS FORMED OVER THE SAINT LAWRENCE RIVER VALLEY WITH A SECONDARY AREA OF LOW PRESSURE OVER DELMARVA. BOTH LOWS WILL MOVE NORTHEASTWARD EVENTUALLY CONSOLIDATED INTO ONE LOW OVER NEW ENGLAND LATE TONIGHT. HAVE ADDRESSED THREAT FOR HEAVIER CONVECTION WITH A TEMPO GROUP WITH IFR CONDITIONS. DO NOT HAVE THUNDERSTORMS SPECIFICALLY MENTIONED IN TAFS AT TIME. CONVECTION WILL TAPER OFF LATE THIS AFTERNOON INTO THE EVENING. CONDITIONS SHOULD IMPROVE TO VFR FOR A PERIOD THIS EVENING INTO THE OVERNIGHT...HOWEVER A RETURN TO MVFR IS ANTICIPATED WITH IFR POSSIBLE AT KGFL AND KPSF. LIGHT SOUTHERLY WINDS WILL SHIFT TO THE WEST WITH THE PASSAGE OF THE LOWS AND FRONTAL BOUNDARY. OUTLOOK... WED-SAT: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... NO FIRE WX ISSUES EXPECTED OVER THE NEXT FEW DAYS. SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A FRONTAL BOUNDARY IS EXPECTED TODAY. RAINFALL AMOUNTS LOOK TO AVERAGE AROUND ONE HALF INCH...LOCALLY OVER AN INCH WHERE HEAVIER SHOWERS OR THUNDERSTORMS TAKE PLACE. THIS WILL BRING A WETTING RAIN TO THE REGION. RH VALUES WILL ONLY DROP TO 70 TO 80 PERCENT TODAY DUE TO CLOUDS AND RAIN. THEY WILL BE NEAR 100 PERCENT TONIGHT AND DROP TO AROUND 40 TO 60 PERCENT TOMORROW AFTERNOON. LARGE CANADIAN HIGH PRESSURE LOOKS TO TAKE CONTROL OF OUR WEATHER WEDNESDAY THROUGH AT LEAST FRIDAY WITH DRY WEATHER. && .HYDROLOGY... AN APPROACHING FRONTAL BOUNDARY WILL BRING A ROUND OF RAIN SHOWERS AND POSSIBLE THUNDERSTORMS TO THE REGION TODAY. PWAT VALUES WILL RISE TO AROUND 1.50-1.75 INCHES INCHES AHEAD OF THE FRONTAL BOUNDARY. WHILE ANY SHOWER OR THUNDERSTORM WILL BE CAPABLE OF HEAVY DOWNPOURS...THE ATMOSPHERE IS NOT QUITE AS MOIST AS LATE LAST WEEK WHEN SOME FLASH FLOODING OCCURRED ACROSS THE MID HUDSON VALLEY AND NW CT. IN ADDITION...STRONG FLOW ALOFT SHOULD KEEP ANY SHOWERS OR THUNDERSTORMS MOVING RATHER QUICKLY. AS A RESULT...FLASH FLOODING IS NOT ANTICIPATED WITH THIS STORM SYSTEM. SOME MINOR RISES WILL BE POSSIBLE ON AREA RIVERS AND STREAMS...ESPECIALLY ACROSS THOSE AREAS THAT SAW HEAVIER RAIN LAST WEEK. THERE STILL COULD BE PONDING ON ROADWAYS AND AREAS OF POOR DRAINAGE THROUGH TUESDAY EVENING. DRY WEATHER WILL RETURN BY LATE TONIGHT AND CONTINUE THROUGH THE REMAINDER OF THE WEEK. THIS WILL ALLOW RIVER AND STREAMS LEVELS TO RECEDE ONCE MORE. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...FRUGIS/HWJIV NEAR TERM...FRUGIS/SND/HWJIV SHORT TERM...FRUGIS LONG TERM...IAA AVIATION...IAA FIRE WEATHER...FRUGIS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS TAUNTON MA
726 AM EDT TUE AUG 13 2013 .SYNOPSIS... AN APPROACHING COLD FRONT WILL BRING SHOWERS AND EMBEDDED THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL LATER TODAY AND INTO THIS EVENING. DRY AND SEASONABLE WEATHER RETURNS WEDNESDAY AND CONTINUES INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... ***SHOWERS AND EMBEDDED THUNDERSTORMS MAY BRING LOCALLY HEAVY RAINFALL/POOR DRAINAGE STREET FLOODING LATER TODAY*** 7 AM UPDATE... FORECAST MOSTLY ON TRACK. WEAK ECHOS ON CURRENT RADAR IMG LIKELY NOT YET HITTING THE GROUND GIVING DWPT DEPRESSIONS ABOUT 5F OR HIGHER. TWO AREAS OF PRECIPITATION TO WATCH AND TWO SCHOOLS OF THOUGHT BETWEEN LATEST MODEL RUNS. THE NORTHERNMOST BAND IS ASSOCIATED WITH WEAKENING CONVECTION AHEAD OF AN APPROACHING COLD FRONT WHILE THE SOUTHERN BAND IS MORE CLOSELY ASSOCIATED WITH A WARM FRONT WHICH IS PROGGED TO REMAIN MOSTLY S OF THE REGION. HAVE NOTED THAT THESE TWO BANDS WILL FORM TO MAKE A MORE COHESIVE BAND OF RAIN WITH EMBEDDED TSRA WHICH WILL MOVE THROUGH LATE MORNING INTO THE AFTERNOON HOURS /LATEST HRRR SHOWS THIS WELL/. HOWEVER THE TWO OUTCOMES IN MODELS WILL NEED TO BE WATCHED. LATEST NAM SUGGESTS THAT GIVEN BEST INSTABILITY REMAINS S...HEAVIEST RAIN AND TSRA REMAIN S AS WELL...CUTTING OFF BEST MOISTURE AND INSTABILITY...LEADING TO LOWER IMPACT. HOWEVER...RECENT ECMWF RUN IS FURTHER N AND STRONGER WITH THE WAVE. BOTH ARE CURRENTLY HANDLING PRECIP LOCATIONS/STRENGTH WELL...SO WILL NEED TO WATCH HOW INSTABILITY AXIS SHAKES OUT OVER THE NEXT FEW HOURS. THIS MAY DETERMINE HOW ACTIVE THE AFTERNOON IS. ALSO...AM NOTING A SECONDARY DEVELOPMENT OF SHOWERS AND STORMS MORE CLOSELY ASSOCIATED WITH THE FRONT FOR LATE AFTERNOON/EVENING AFTER THIS INITIAL WEAKENING CONVECTIVE BAND MOVES OUT. PREVIOUS DISCUSSION FOLLOWS... CALM WINDS AND DEWPOINTS IN THE 60S HAS ALLOWED AREAS OF DENSE FOG TO DEVELOP ALONG THE SOUTH COAST/CAPE AND ISLANDS VERY EARLY THIS MORNING. THIS HAS PROMPTED THE ISSUANCE OF A DENSE FOG ADVISORY THROUGH 9 AM ACROSS THIS REGION. THE FOG SHOULD BURN OFF BY MID TO LATE MORNING. OTHERWISE...SHOWERS AND THUNDERSTORMS HAVE BROKEN OUT EARLY THIS MORNING ACROSS WESTERN NY/WESTERN PA AHEAD OF A STRONG SHORTWAVE. THIS ACTIVITY WILL WORK EAST AND OVERSPREAD SOUTHERN NEW ENGLAND LATER THIS MORNING AND EARLY AFTERNOON. CONFIDENCE IS FAIRLY HIGH THAT THIS PRECIPITATION WILL BE WIDESPREAD...SO SHOWED AT LEAST LOW END CATEGORICAL POPS ACROSS MOST AREAS. THERE ARE TWO MAIN CONCERNS TODAY WHICH WE WILL OUTLINE BELOW: 1) FL0ODING POTENTIAL: PRETTY GOOD JET DYNAMICS/FORCING ARE ASSOCIATED WITH THIS SHORTWAVE TROUGH...SO EXPECT LOCALLY HEAVY RAINFALL AND NUISANCE POOR DRAINAGE STREET FLOODING. WILL INCLUDE THIS WORDING IN OUR FORECAST AND HAZARDOUS WEATHER OUTLOOK. DECIDED NOT TO ISSUE A FLASH FLOOD WATCH AT THIS TIME FOR A COUPLE OF REASONS. THE FIRST WAS THAT PWATS ARE HIGH...BUT GENERALLY UNDER 2 INCHES/SURFACE DEWPOINTS SHOULD REMAIN BELOW 70 AND BETTER INSTABILITY WILL RESIDE TO OUR SOUTH. NONETHELESS...GIVEN FAIRLY STRONG FORCING THERE IS STILL A LOW PROBABILITY FOR VERY LOCALIZED FLASH FLOODING. LATER SHIFTS WILL HAVE TO KEEP A CLOSE EYE ON THIS POTENTIAL IN CASE A SHORT FUSED FLASH FLOOD WATCH IS NEEDED. 2) SEVERE WEATHER POTENTIAL: PRETTY GOOD JET DYNAMIC WILL RESULT IN 0 TO 6 KM SHEAR VALUES ON THE ORDER OF 35 TO 45 KNOTS TODAY. THE PROBLEM IS THAT WITH A FAIR AMOUNT OF CLOUD COVER AND POOR MID LEVEL LAPSE RATES...INSTABILITY WILL REMAIN QUITE LIMITED WITH MLCAPE VALUE GENERALLY UNDER 1000 J/KG. THEREFORE...THINKING THAT THE MAIN THREAT WILL BE HEAVY RAINFALL AND POOR DRAINAGE STREET FLOODING. HOWEVER...GIVEN THAT THE 0 TO 6 KM SHEAR WILL BE NEAR OR ABOVE 40 KNOTS WE CAN/T COMPLETELY LET OUR GUARD DOWN. IF MORE INSTABILITY DEVELOPS THAN EXPECTED THERE WOULD BE THE THREAT FOR A FEW SEVERE THUNDERSTORMS. SOMETHING WILL NEED TO KEEP AN EYE ON BUT APPEARS TO BE A LOW PROBABILITY AT THIS POINT. && .SHORT TERM /WEDNESDAY/... TONIGHT... A FEW SHOWERS AND ISOLATED THUNDERSTORMS MAY LINGER DURING THE EVENING ESPECIALLY ALONG THE COAST. OTHERWISE...MUCH DRIER MID LEVEL AIR WILL WORK INTO THE REGION BY LATE EVENING BRINGING AN END TO MOST OF THE PRECIPITATION. MAY SEE SOME PATCHY GROUND FOG DEVELOP IN THE TYPICALLY PRONE LOCATIONS...ESPECIALLY IN AREAS THAT SEE A FAIR AMOUNT OF RAIN TODAY. LOW TEMPS WILL MAINLY BE IN THE UPPER 50S AND LOWER 60S. WEDNESDAY... A MIXTURE OF CLOUDS/SUN ALONG WITH GUSTY NORTHWEST WINDS BEHIND THE COLD FRONT ON WED. LOW RISK OF A BRIEF SPRINKLE/SPOT SHOWER ACROSS OUR FAR NORTHWEST ZONES...BUT BASICALLY A DRY AND BEAUTIFUL DAY EXPECTED FOR THE MIDDLE OF AUGUST. HIGH TEMPS WILL MAINLY BE IN THE 70S WITH LOW HUMIDITY. IN FACT...SOME OF THE HIGHEST TERRAIN WILL STRUGGLE TO REACH 70! && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGHLIGHTS... * QUIET...SEASONABLE WEATHER WED THRU THE WEEKEND * POSSIBILITY OF SOME RAIN EARLY NEXT WEEK OVERVIEW AND MODEL PREFERENCES... 13/00Z LONG RANGE GUIDANCE CONTINUES TO SHOW QUITE GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. INITIAL WEAK CUTOFF IS PROGGED TO SLIDE INTO THE CANADIAN MARITIMES AS A SECOND CUTOFF DIVES S FROM HUDSON BAY IN THE PERSISTENT BROAD TROF OVER ERN CANADA AND THE NORTHEAST CONUS. HOWEVER...THE LONGWAVE TROF AND THIS SECOND CUTOFF LOOK TO HAVE LITTLE EFFECT ON THE REGION AS STRONG RIDGING ALONG THE SOUTHERN HALF OF THE CONUS COMBINES WITH RIDGING IN THE ATLANTIC TO YIELD SUBSIDENCE AND BROAD SFC HIGH PRES OVER THE NORTHEAST. GIVEN THERE IS GOOD AGREEMENT BETWEEN BOTH OPERATIONAL MODELS AND THEIR COUNTERPART ENSEMBLES...HAVE REASONABLY HIGH CONFIDENCE THAT THIS HIGH PRES WILL YIELD A MOSTLY DRY FORECAST THROUGH EARLY NEXT WEEK. GIVEN THIS...WILL USE A GFS/ECWMF BLEND AS A BASELINE FOR THIS FORECAST UPDATE. WED NIGHT INTO FRI... HIGH PRES GRADUALLY SLIDES IN FROM THE W THROUGH THE PERIOD. WITH THE HIGH PRES CENTER REMAINING W OF THE REGION...EXPECT US TO REMAIN ON THE COOLER SIDE OF THE HIGH INITIALLY. H85 TEMPS RANGE BETWEEN +8C AND ABOUT +11C...SO HIGHS SHOULD START THU AROUND THE MID 70S...INCREASING TO THE UPPER 70S AND LOW 80S BY FRI AFTER SOME AIRMASS MODIFICATION. OVERNIGHT MINS WILL BE ON THE COOL SIDE WITH LOW HUMIDITY /AND THEREFORE LOW DWPTS/ WITH LIGHT FLOW AND CLEAR SKIES. EXPECTING MINS DIPPING AS LOW AS THE MID 40S IN NORMALLY COOLER SPOTS. MID 50S IN THE WARMER SPOTS. THIS COMING WEEKEND... A WARM FRONT IS EXPECTED TO BEGIN A GRADUAL SLIDE TO THE N THROUGH THE WEEKEND...BUT WITH HIGH PRES IN PLACE OVER THE REGION AND VERY SLOWLY SLIDING TO THE E...EXPECTING MOSTLY DRY CONDITIONS ACROSS SRN NEW ENGLAND DESPITE THIS APPROACHING FRONT. GFS CURRENTLY SUGGESTS HIGHEST POTENTIAL FOR SOME PRECIP...BUT IT TOO KEEPS MOST OF ITS GENERATED QPF TO THE W. MID LVL TEMPS DO INCREASE SOMEWHAT...REACHING +10 TO +13C...SO TEMPS LEAN NEAR TO SLIGHTLY WARMER THAN NORMAL. EARLY NEXT WEEK... DIFFERENCES IN THE TIMING OF A STRONGER SHORTWAVE EFFECTING THE REGION GIVES WAY TO LOWER CONFIDENCE HERE...BUT IT APPEARS THAT THERE WILL BE A BIT HIGHER CHANCE FOR SOME PRECIP PARTICULARLY BY TUE. WILL BE INCREASING TO SOME SLIGHT CHANCE POPS...CLOSER TO THE ECWMF SOLUTION...WHICH SUGGESTS THE WARM FRONT LIFTS FAR ENOUGH N TO AFFECT THE REGION WITH THIS SHORTWAVE PASSAGE. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE CONFIDENCE TODAY AND TONIGHT. HIGH CONFIDENCE ON WEDNESDAY. TODAY...DENSE FOG BURNS OFF IN NEXT COUPLE OF HOURS. AS A BAND OF RAIN WITH EMBEDDED THUNDERSTORMS MOVES OVER FROM THE W FROM MID MORNING INTO THE AFTERNOON...WILL SEE A MIX OF VFR TO IFR...WITH THE IFR CONDITIONS MOSTLY DUE TO LOW VISIBILITIES IN POCKETS OF HEAVIER RAIN. EXACT TIMING REMAINS UNCERTAIN. TONIGHT...LEFT OVER SHOWERS/ISOLATED THUNDERSTORMS THIS EVENING. OTHERWISE...MAY SEE SOME LINGERING LOW CLOUDS AND FOG PATCHES PERSIST AT SOME /ESPECIALLY EASTERN/ TERMINALS INTO THE OVERNIGHT HOURS. AREAL COVERAGE OF LOW CLOUDS AND FOG PATCHES ARE UNCERTAIN. WEDNESDAY...ANY LEFT OVER MVFR-IFR CONDITIONS IN SCATTERED LOW CLOUDS/FOG PATCHES WILL IMPROVE TO VFR NOT LONG AFTER SUNRISE. OTHERWISE...VFR CONDITIONS. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING. MAY SEE BOUNCING BETWEEN VFR AND LOWER CATEGORIES WITH RAIN LATE THIS MORNING/AFTERNOON. KBDL TERMINAL...MODERATE CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... HIGH CONFIDENCE. VFR. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY AND TONIGHT...HIGH CONFIDENCE. WINDS AND SEAS WILL REMAIN BELOW SCA THRESHOLDS WITH A RELATIVELY WEAK PRESSURE GRADIENT IN PLACE. THE MAIN CONCERN EARLY THIS MORNING WILL BE FOR DENSE FOG ACROSS OUR SOUTHERN WATERS. THIS FOG SHOULD BURN OFF TO AT LEAST SOME DEGREE BY MID TO LATE MORNING. THE OTHER CONCERN WILL BE FOR EMBEDDED THUNDERSTORMS TO WORK ACROSS THE WATERS...MAINLY THIS AFTERNOON AND EVENING. WEDNESDAY...MODERATE CONFIDENCE. NORTHWEST WIND GUSTS OF 25 KNOTS ARE EXPECTED NEAR SHORE WITH GOOD MIXING BEHIND THE COLD FRONT. ITS 3RD PERIOD SO DID NOT GO WITH ANY HEADLINES AT THIS POINT...BUT LATER SHIFTS MAY NEED TO CONSIDER A SCA FOR SOME OF OUR NEAR SHORE WATERS. MAY ALSO SEE SOME 3 TO 5 FOOT SEAS DEVELOP ACROSS OUR SOUTHERN MOST ATLANTIC WATERS...WHICH MAY ALSO NEED TO BE CONSIDERED FOR HEADLINES. OUTLOOK...WEDNESDAY THROUGH SATURDAY... HIGH CONFIDENCE. QUIET BOATING WEATHER EXPECTED. WINDS WILL SHIFT DIRECTION AS HIGH PRESSURE BUILDS OVER SOUTHERN NEW ENGLAND AND THE WATERS BUT WILL REMAIN BELOW 25 KTS...SAVE FOR POSSIBLY WED EVENING. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MAZ020>024. NH...NONE. RI...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR RIZ006>008. MARINE...NONE. && $$ SYNOPSIS...FRANK/DOODY NEAR TERM...FRANK/DOODY SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY MARINE...FRANK/DOODY
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
427 AM EDT Tue Aug 13 2013 .NEAR TERM [Today and Tonight]... As has been quite typical during this very unusual summer, it has been nearly impossible to keep an established upper level ridge in place across the SE U.S. So, while on Monday, many areas experienced an extended period (during the day) of hot and dry conditions with many high temps in the mid to upper 90s, today is expected to be our transition back to a wet and trough dominated pattern. Although the more significant cooler and wetter weather will likely be reserved for Wednesday and onward for the next several days at least, PoPs will clearly be on the increase from NW to SE over the CWA today. Max temps may still reach the lower 90s to the west and the middle 90s well to the east, but by this afternoon, PoPs are expected to reach the likely category (60-70% with locally heavy rainfall likely) across the FL Panhandle, SE AL, and the NW 1/3 of our GA zones, and PWATs will be back on the increase with many other favorable factors in place to initiate convection. Elsewhere, the PoPs are expected to gradually taper off from NW to SE, with 50s and 40s over the remainder of our GA zones, then finally down to the 40% to 20% range across the remainder of the FL Big Bend, so with this much variation, mesoscale updates will likely be needed to the fcst today, with heavy weighting given to the Hi-Res Models (including our local and NCEP`s WRF runs, and the HRRR (High Resolution Rapid Refresh). Tonight`s fcst could be even more complex in terms of PoPs and timing, so leaned heavily on a combination of our CAM (Convective Allowing Model) output and locally generated confidence grids. && .SHORT TERM [Wednesday through Thursday]... There remains high confidence in widespread rain coverage for the short term period (Wednesday to Thursday). The ingredients include a stalling low-level front, a weak upstream trough in the mid- upper levels of the atmosphere, and a plume of deep moisture. The NAM, GFS, and ECMWF all show widespread rainfall in this 36-hour period of around an inch, with locally higher amounts. Therefore, PoPs were pushed above model guidance again - with widespread "likely" (60-70%) values during the daytime hours, and high chance (40-50%) at night. This equates to rain chances roughly 20-30% above climatology during the entire period. Given very weak flow (and thus slow storm motions) and high PWATs, the environment should support locally heavy rainfall. Heavy rain wording was once again included in the forecast. Given the abundance of rain and clouds, high temperatures were kept slightly below the model consensus, and low temperatures slightly above consensus. && .LONG TERM [Thursday Night through Monday]... A long wave trough will remain in place from the Great Lakes to the central Gulf Coast early in the period as a reinforcing short wave in the northern plains drops into the trough, resulting in a closed low over the Lower Mississippi Valley by Saturday. This low gradually fills and weakens, leaving behind a weak trough for early next week with an axis still to our west. The end result is a prolonged period of rain for the southeast with periods of heavy rain likely. Total rainfall from the GFS indicates areas of rain up to 10 inches across the FL panhandle through Monday, due in part to its development of a tropical cyclone in the gulf which it brings into the FL panhandle Saturday. The Canadian also generates a tropical system similar to the GFS, however the ECMWF does not generate a tropical system and therefore depicts rainfall totals through Monday of about 5 inches. Confidence of a period of heavy rain is high, and if the GFS-advertised tropical system does develop then local rainfall amounts could be double or triple the current WPC 5.5" totals. && .AVIATION [through 12 UTC Wednesday]... VFR conditions are expected to prevail for the remainder of the overnight hours tonight (with the possible exception of MVFR CIGS at ECP), but the greater concern as we move forward with time will be the increasing probabilities and coverage of showers and thunderstorms across the terminals. Initially, the most pessimistic flying conditions will be at the northern and western terminals (DHN, ECP, and ABY), but MVFR/IFR restrictions will likely spread eastward towards TLH and VLD along with the convection later this afternoon and evening. However, when all is said and done, the most challenging portion of the fcst will likely be between 06 and 12 UTC on Wed., where if there is a significant break in the convection and residual mid and upper level clouds, very low CIGS and or vis could develop and become problematic. && .MARINE... A gradual increase in the pressure gradient over the next few days should cause winds to increase from the 5-10 knot range more into the 10-15 knot range, with perhaps a slight increase in seas. We will be keeping an eye on the western Caribbean and southern Gulf of Mexico for tropical development in the next five days. The NHC has posted a "low chance" of development for those areas, and therefore we mentioned this possibility in the CWF text. && .FIRE WEATHER... ed flag conditions are not expected over the next several days, as wet and more humid weather will make a quick return to the region. && .HYDROLOGY... Widespread rainfall totals of at least 3 inches appear likely over the next week, which will likely cause an increase in flows on area rivers - particularly after Thursday. The vast majority of rivers and creeks in the area are below bankfull levels thanks to a relatively dry period in the past week or so. Therefore, it will likely take a few days worth of heavy rainfall to cause more widespread increases in the flows on area rivers. It is too early to determine flooding potential on specific rivers, as that will ultimately hinge on the location and intensity of the heaviest rainfall. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 93 75 91 75 89 / 40 30 60 50 70 Panama City 90 78 88 77 86 / 50 60 60 50 70 Dothan 92 74 87 74 87 / 70 30 70 50 70 Albany 93 75 88 74 88 / 60 30 70 50 70 Valdosta 95 74 91 74 90 / 40 30 60 50 70 Cross City 94 75 93 74 90 / 20 30 40 30 40 Apalachicola 89 79 88 78 86 / 30 50 50 40 60 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Gould SHORT TERM...Lamers LONG TERM...Hollingsworth AVIATION...Gould MARINE...Lamers FIRE WEATHER...Gould HYDROLOGY...Lamers
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
325 PM EDT TUE AUG 13 2013 .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... SHORT RANGE MODELS CONTINUE TO SHOW A COLD FRONT...CURRENTLY ACROSS TN... SAGGING ACROSS NORTH GA TONIGHT AND STALLING ACROSS CENTRAL GA WEDNESDAY AFTERNOON. REGIONAL RADARS SHOW SCATTERED SHOWERS AND THUNDERSTORMS BEGINNING TO DEVELOP ACROSS THE FORECAST AREA AS AN UPPER DISTURBANCE APPROACHES FROM THE WEST. EXPECT A WEAK SURFACE TROUGH TO HELP PROVIDE A FOCUS ACROSS NORTH GA THIS AFTERNOON AND RADAR TRENDS SUPPORT THAT...WITH A SCATTERED LINE OF CONVECTION DEVELOPING FROM WEST OF ROME...EASTWARD TO JASPER AND CLEVELAND. EXPECT THIS ACTIVITY TO SAG SOUTHWARD THROUGH THE LATE AFTERNOON AND EVENING HOURS. ADDITIONAL SCATTERED TO NUMEROUS CONVECTION IS DEVELOPING ACROSS PARTS OF CENTRAL GA WHERE THE GREATER INSTABILITIES AND DEEPER MOISTURE ARE POOLED. THE HRRR MODEL CLUSTERS MOST OF THE CONVECTIVE ACTIVITY ACROSS THE CENTRAL ZONES... FROM AREAS AROUND COLUMBUS TO MACON TO MILLEDGEVILLE AND SOUTHWARD DURING THE LATE AFTERNOON AND EVENING HOURS. THUNDERSTORM ACTIVITY MAY PERSIST THROUGH MID EVENING BEFORE DIMINISHING TO MAINLY SHOWERS. SCATTERED SHOWERS MAY PERSIST OVERNIGHT ALONG AND AHEAD OF THE COLD FRONT... BUT ANY THUNDERSTORM ACTIVITY SHOULD BE VERY ISOLATED AT BEST OVERNIGHT. THE MAIN THUNDERSTORM THREAT THROUGH THE EVENING WILL CONTINUE TO BE LOCALLY HEAVY RAIN AND POSSIBLE BRIEF FLOODING. HOWEVER... WITH 2500-3000 CAPE... CANNOT RULE OUT A PULSE STRONG STORM PRODUCING WIND GUSTS TO 40-45 MPH AND POSSIBLY SOME SMALL HAIL. MODELS AGREE ON DRIER AIR SPREADING IN BEHIND THE FRONT ACROSS NORTH GA BY EARLY WEDNESDAY... SO WILL SHOW THE GREATER RAIN CHANCES ACROSS CENTRAL GA ON WEDNESDAY...AND MAINLY ALONG AND SOUTH OF A LA GRANGE TO WARRENTON LINE...WITH ONLY A LOW CHANCE IN THE ATLANTA METRO AREA FOR WEDNESDAY AFTERNOON. LOCALLY HEAVY RAIN WILL REMAIN A THREAT ACROSS CENTRAL GA WEDNESDAY AFTERNOON AS THE FRONT PROVIDES A FOCUS FOR TRAINING CONVECTION. MODELS SHOW GENERALLY ONE QUARTER TO ONE HALF INCH FROM COLUMBUS TO MACON AND SOUTHWARD ON WEDNESDAY... BUT ISOLATED HIGHER AMOUNTS OF 1 TO 3 INCHES ARE POSSIBLE. ALTHOUGH CANNOT RULE OUT A PULSE STRONG TO SEVERE STORM ALONG OR SOUTH OF THE FRONT WEDNESDAY AFTERNOON... NOT EXPECTING ANYTHING WIDESPREAD AND THE GREATER STRONG STORM THREAT SHOULD BE JUST SOUTH OF THE FORECAST AREA WEDNESDAY AFTERNOON AND EVENING. OTHERWISE... AS FOR TEMPS A MODEL BLEND THROUGH THE SHORT TERM LOOKED REASONABLE. 39 .LONG TERM /THURSDAY THROUGH TUESDAY/... GUIDANCE CONTINUES TO POINT TO A WET EXTENDED PERIOD. AS THE FRONT SAGS SOUTH OF THE AREA TROUGH THE SHORT TERM...SURFACE HIGH UNDER CONFLUENT FLOW ALOFT WILL SLIP EAST AND ACROSS THE APPALACHIANS IN A HYBRID DAMMING EVENT. THE QUESTION WILL BE HOW MUCH GULF MOISTURE WILL INTERACT WITH THE DAMMING. FOR THURSDAY...WITH THE STALLED FRONT AND ONSET OF HYBRID CAD...HPC AND SYNOPTIC MODELS KEEP THE BEST PRECIP ACROSS CENTRAL GEORGIA...WITH A GOOD INCH OF BASIN-AVERAGE QPF DURING THE DAY. THIS TREND CONTINUES INTO FRIDAY. BESIDES THE PRECIP HOWEVER...THE BIGGEST SENSIBLE IMPACT WILL BE TEMPS. CURRENT HIGH TEMPS FOR THURSDAY THROUGH SATURDAY DO NOT BRING NORTH GEORGIA OUT OF THE 70S...AND REALLY ONLY INTO THE MID 80S IN SOUTHERN ZONES. POSSIBLY A SLIGHT WARMING TREND BY A DEGREE OR SO ON SUNDAY BUT THIS REMAINS TO BE SEEN. THESE FORECAST MAX TEMPS ARE A GOOD 10 DEGREES COOLER THAN SEASONAL NORMALS... THE KIND OF IMPACTS NORMALLY SEEN WITH CLASSICAL CAD RATHER THAN HYBRID CAD. 00Z ECMWF CONTINUES TO TAKE THE TROPICAL WAVE /CURRENTLY IN THE CARIBBEAN/ FURTHER WEST TOWARD THE YUCATAN...WHILE GFS AND CANADIAN BRING IT INTO THE GULF AND CLOSE TO THE COAST FRIDAY NIGHT. FOR WHAT ITS WORTH...THE CANADIAN IS STRONGER AND FURTHER WEST WITH THE SURFACE LOW THAN THE GFS...WHICH WOULD POSSIBLY INDICATE SEVERE POTENTIAL ON SATURDAY...BUT IT IS A BIT OF AN OUTLIER THERE. ECMWF IS DRIEST WHILE GFS/CMC ARE WETTER SOLUTIONS. HPC NOT GOING NEARLY AS HIGH AS THE GFS BUT EVEN SO...WITH THE PROLONGED WET PERIOD ACROSS ESPECIALLY CENTRAL GEORGIA FROM THE SHORT TERM FRONT...THERE IS SOME CONCERN ABOUT THE RAINFALL PILING UP. HAVE NOT DONE A COMPLETE DIAGNOSIS TO DETERMINE IF THE THURSDAY-FRIDAY RAIN WOULD QUALIFY AS A PRE /PREDECESSOR RAINFALL EVENT/ BUT IN ANY CASE THE 7-DAY QPF TOTAL FROM HPC ARE UPWARDS OF 6 INCHES ACROSS PORTIONS OF CENTRAL GEORGIA. THIS BEING BASIN-AVERAGE...IMPLYING THAT SOME AREAS COULD GET SUBSTANTIALLY MORE /AND OF COURSE SOME AREAS SUBSTANTIALLY LESS/. ALL INTERESTS SHOULD STAY TUNED TO LATEST FORECASTS AS THIS IS REFINED OVER THE NEXT FEW DAYS. SO OVERALL...REALLY MADE ONLY MINOR CHANGES TO PREVIOUS EXTENDED FORECAST. REFINED AND ADDED SOME DETAIL TO DAYS 4 AND 5 ESPECIALLY WITH TEMPS WINDS AND DEWPOINTS /VERY LITTLE IF ANY CHANGE TO POPS/ AND MADE SOME MINOR ADJUSTMENTS TO HIGH TEMPS THROUGH THE REST OF THE PERIOD TO REFLECT THE PROLONGED COOL SPELL. TDP && .AVIATION... 18Z UPDATE... VFR CIGS WILL PERSIST THROUGH THE TAF PERIOD. WRF AND HRRR MODELS SHOW SCT CONVECTION BRUSHING ATL AROUND 21-23Z TODAY... SO WILL SHOW TEMPO -TSRA AT THIS TIME. A COLD FRONT PUSHES INTO NORTH GA TONIGHT AND SPREADS SOME DRIER AIR SOUTHWARD BY WED MORN. THIS SHOULD HINDER ANY THREAT OF LOW CIGS AT ATL BY EARLY WED MORN. EXPECT A WNW WIND AROUND 10G15KTS THIS AFTERNOON TO BECOME MORE NW AND DIMINISH TO AROUND 6-8KTS BY 03Z... THEN NNW WINDS AROUND 8-10KTS BY 15Z WED. THE FRONT MOVES SOUTH OF ATL EARLY WED WITH A DRIER NW FLOW...SO NO MENTION OF TSRA FOR ATLANTA AREA ON WED. //ATL CONFIDENCE...18Z UPDATE... MEDIUM CONFIDENCE ON TEMPO -TSRA THIS AFTERNOON. HIGH ON ALL OTHER ELEMENTS. 39 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 69 88 68 78 / 50 40 20 30 ATLANTA 70 86 69 79 / 50 30 20 50 BLAIRSVILLE 64 81 64 76 / 50 20 20 30 CARTERSVILLE 68 86 64 82 / 50 20 20 30 COLUMBUS 73 87 71 84 / 40 60 40 80 GAINESVILLE 69 85 68 76 / 50 20 20 30 MACON 72 89 71 82 / 40 60 50 80 ROME 68 89 63 83 / 50 20 10 30 PEACHTREE CITY 70 86 66 79 / 40 40 20 50 VIDALIA 74 88 71 84 / 30 60 60 80 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...39 LONG TERM....TDP AVIATION...39
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
150 PM EDT TUE AUG 13 2013 .MORNING UPDATE... /ISSUED AT 1107 AM EDT TUE AUG 13 2013/ LATEST SURFACE ANALYSIS SHOWS A WEAK TROUGH ACROSS NORTH GA WITH A COLD FRONT ACROSS WEST TN AND INTO THE OHIO VALLEY. THE UPPER LEVELS SHOW WEAK DISTURBANCES APPROACHING FROM THE WEST. CONVECTIVE MODELS INDICATE POSSIBLY TWO ROUNDS OF CONVECTION THIS AFTERNOON AND EVENING...THE FIRST POSSIBLY FOCUSED ALONG THE SURFACE TROUGH TO THE NORTH AND THIS ACTIVITY SAGS SOUTH INTO CENTRAL GA DURING THE MID TO LATE AFTERNOON HOURS. ANOTHER ROUND PUSHES INTO NORTH GA AHEAD OF THE COLD FRONT LATE THIS AFTERNOON-EARLY EVENING AND ALSO SAGS SOUTH OVERNIGHT... ALTHO THIS ACTIVITY WILL WEAKEN TO MAINLY JUST SHOWERS BY LATE EVENING. HAVE UPDATED ZONES TO TWEAK LIKELY POPS MORE INTO WEST CENTRAL ZONES THIS AFTERNOON AND HELD ONTO SLIGHTLY HIGHER POPS NORTH THROUGH THE EVENING HOURS. MORNING SOUNDING SUGGEST LOCALLY HEAVY RAIN WILL CONTINUE TO BE THE MAIN THREAT WITH SOUNDING SHOWING NEAR 2 INCH PW`S. FREQUENT LIGHTNING...WIND GUSTS TO 40 MPH... AND SMALL HAIL WILL ALSO BE POSSIBLE THROUGH MID EVENING WITH THE STRONGER STORMS. /39 .PREVIOUS DISCUSSIONS /ISSUED AT 440 AM EDT TUE AUG 13 2013/... SHORT TERM /TODAY THROUGH WEDNESDAY/... VARIOUS LEVELS OF CLOUDS OVER GA THIS MORNING DUE TO PREVIOUS TSTMS MONDAY EVENING. LOW STRATUS IS DEVELOPING OVER WET GROUND AT THIS TIME FROM RAINFALL IN THE PAST 24 HOURS. A COLD FRONT WAS MOVING SOUTHEAST THROUGH KY AND AR WHILE A NEAR ZONAL FLOW PREVAILED OVER GA. EXPECT ENOUGH DIURNAL HEATING AND SYNOPTIC SCALE FORCING IN ADVANCE OF THE COLD FRONT TODAY TO LIFT THE LOW STRATUS AND THEN DOMINATE WITH A BKN CU FIELD. WITH SO MUCH TROPICAL MOISTURE AVAILABLE...PWS NEAR 2 INCHES...EXPECT SCATTERED TSTMS TO DEVELOP AS EARLY AS 1000 AM EDT OVER NORTH GA IN ADVANCE OF THE APPROACHING COLD FRONT THROUGH THE TN VALLEY. THE REMAINDER OF NORTH GA INCLUDING THE ATL AREA WILL BE AROUND NOON OR LATER. THE FRONT SHOULD ENTER NORTHWEST GA AROUND 800 PM EDT AND CONTINUE MOVING INTO CENTRAL GA BY WEDNESDAY MORNING. THE SCATTERED TO NUMEROUS TSTMS THIS AFTERNOON SHOULD DIMINISH TO ISOLATED OVERNIGHT AS THE AIRMASS OVER GA GRADUALLY STABILIZES FROM PRECIPITATION AND EVAPORATIONAL COOLING. THE NEARLY STATIONARY FRONT OVER CENTRAL AND SOUTH GA COMBINED WITH AN APPROACHING UPPER LEVEL DISTURBANCE WILL INITIATE NUMEROUS TSTMS OVER CENTRAL GA BY WEDNESDAY AFTERNOON AND EVENING. ISOLATED TO SCATTERED TSTMS CAN BE EXPECTED OVER NORTH GA. FAVORED AND INCREASED THE WETTER NAM SOLUTION DURING THE FORECAST PERIOD. TEMPS WERE A MET/MAV MOS GUIDANCE BLEND. 16 LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... GFS AND EUROPEAN MODELS INDICATING AN INCREASINGLY WET PERIOD. A STATIONARY FRONT WILL LIE ACROSS THE CENTRAL TO S GA AREA TO START THE LONG TERM WITH AN UPPER LEVEL TROUGH EXPECTED TO DEVELOP IN THE THURSDAY TO FRIDAY TIME FRAME OVER THE MID U.S AND DRIFT E. THIS WILL ALLOW FOR MOIST SOUTHERLY FLOW TO DEVELOP ALONG WITH A CAD TYPE AIRMASS OVER THE NORTH. 50-80 PERCENT POPS CAN BE EXPECTED FOR MUCH OF THE AREA WEDNESDAY NIGHT THROUGH MONDAY AND HAVE LEANED HARD ON HPC GUIDANCE WITH HIGHER POPS AND LOWER DAYTIME TEMPERATURES. THE UPPER TROUGH WILL WEAKEN ON MONDAY WITH THE GFS AND EUROPEAN DIFFERING ON HOW MUCH IT WEAKENS INTO TUESDAY. SIGNIFICANT RAINFALL CAN BE EXPECTED DURING THIS PERIOD FAVORING CENTRAL GA MORE THAN N GA. THE GFS IS INDICATING A HEAVY PRECIP BULLSEYE AND IS MOST LIKELY OVERDONE COMPARED TO THE MORE REASONABLE LOOKING EUROPEAN. HIGH TEMPERATURES WILL BE ON THE ORDER OF 5-10 DEGREES BELOW NORMAL. LOW TEMPERATURES WILL BE CLOSE TO SLIGHTLY BELOW NORMAL FOR MUCH OF THE PERIOD. BDL && .AVIATION... 18Z UPDATE... VFR CIGS WILL PERSIST THROUGH THE TAF PERIOD. WRF AND HRRR MODELS SHOW SCT CONVECTION BRUSHING ATL AROUND 21-23Z TODAY... SO WILL SHOW TEMPO -TSRA AT THIS TIME. A COLD FRONT PUSHES INTO NORTH GA TONIGHT AND SPREADS SOME DRIER AIR SOUTHWARD BY WED MORN. THIS SHOULD HINDER ANY THREAT OF LOW CIGS AT ATL BY EARLY WED MORN. EXPECT A WNW WIND AROUND 10G15KTS THIS AFTERNOON TO BECOME MORE NW AND DIMINISH TO AROUND 6-8KTS BY 03Z... THEN NNW WINDS AROUND 8-10KTS BY 15Z WED. THE FRONT MOVES SOUTH OF ATL EARLY WED WITH A DRIER NW FLOW...SO NO MENTION OF TSRA FOR ATLANTA AREA ON WED. //ATL CONFIDENCE...18Z UPDATE... MEDIUM CONFIDENCE ON TEMPO -TSRA THIS AFTERNOON. HIGH ON ALL OTHER ELEMENTS. 39 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 89 69 87 69 / 50 40 50 50 ATLANTA 87 70 85 70 / 60 40 50 40 BLAIRSVILLE 82 65 82 64 / 70 30 20 40 CARTERSVILLE 87 68 88 66 / 90 50 20 30 COLUMBUS 91 73 88 71 / 70 50 60 50 GAINESVILLE 87 70 85 69 / 60 50 40 40 MACON 91 72 88 71 / 60 30 60 50 ROME 88 68 88 65 / 90 40 20 20 PEACHTREE CITY 87 69 86 70 / 60 40 60 40 VIDALIA 93 74 90 72 / 50 30 60 50 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...16/39 LONG TERM....BDL/25 AVIATION...39
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1228 PM CDT TUE AUG 13 2013 .DISCUSSION... 1050 AM CDT FOR MORNING UPDATE... NO SIGNIFICANT CHANGES TO NEAR TERM FORECAST THIS MORNING. ONLY MINOR TWEAKS TO HOURLY TEMP/SKY COVER GRIDS BASED ON CURRENT OBS AND SATELLITE TRENDS. SPRAWLING CANADIAN SURFACE HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST FROM THE LAKE WINNIPEG AREA OF SOUTHERN MANITOBA LATE THIS MORNING...WITH BREEZY NORTH-NORTHEAST SURFACE WINDS AHEAD OF THE ADVANCING ANTICYCLONE BRINGING COOLER AND DRIER ALMOST EARLY-AUTUMN LIKE AIR TO THE FORECAST AREA. IN FACT...THE COOL AIR ALOFT...WITH +5C SAMPLED AT 850 MB IN THE GREEN BAY WISC 12Z RAOB...HAS LED TO DEVELOPMENT OF LAKE EFFECT STRATOCU ACROSS LAKE MICHIGAN. THIS LAKE INDUCED CLOUD COVER WAS SPREADING INLAND INTO THE CHICAGO METRO AREA DOWNWIND OF THE LAKE. ASSESSMENT OF THE MORNING RAOB DATA AND MODEL LOW-LEVEL THERMAL FIELDS CONTINUES TO INDICATE A RATHER COOL DAY FOR MID-AUGUST...WITH HIGHS RANGING FROM PERHAPS THE UPPER 60S ALONG THE LAKE MICHIGAN SHORE...TO THE LOW-MID 70S IN THE WARMEST INLAND REACHES SUCH AS DIXON/PONTIAC. DEW POINT TEMPS IN THE MID-UPPER 40S WILL MAKE FOR DRY CONDITIONS THIS AFTERNOON AS WELL...AS WINDS BEGIN TO DIMINISH WITH THE GRADIENT GRADUALLY WEAKENING WITH THE APPROACH OF THE HIGH PRESSURE CENTER. RATZER //PREV DISCUSSION... 327 AM CDT WITH EXPANSIVE SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTHWEST AND THEN ESTABLISHING ITSELF OVER THE GREAT LAKES REGION THROUGH THE WEEKEND...THERE ARE NO REAL WEATHER CONCERNS FOR THE AREA. HOWEVER...AN UNSEASONABLY COOL AIR MASS IS PLUNGING SOUTH DOWN LAKE MICHIGAN BEHIND A SECONDARY COLD FRONT AND SHARP TROUGH AXIS SEEN WELL ON WATER VAPOR IMAGERY EARLY THIS MORNING. THIS WILL QUICKLY TRANSPORT THE MID SINGLE DIGIT 850 MB TEMPS OVER ONTARIO ON THE 00Z RAOB TO OUR AREA BY THIS AFTERNOON...WHICH WILL MAKE FOR MORE FALL-LIKE THAN SUMMER-LIKE HIGH TEMPERATURES PRIMARILY IN THE LOWER 70S...WITH A SCATTERING OF MID 70S READINGS IN THE FAR SOUTH AND WEST. DESPITE A VERY DRY AIRMASS...STEEPENING LOW LEVEL LAPSE RATES AND NEAR SATURATION AT ABOUT 800 MB WILL LIKELY RESULT IN A BLOSSOMING STRATOCU DECK BY MID TO LATE MORNING THAT WILL GRADUALLY DISSIPATE THROUGH THE EVENING. IN ADDITION...FORECAST SOUNDINGS INDICATE FAVORABLE PROFILES FOR GENERATION OF LAKE EFFECT CLOUDS WHICH ARE EXPECTED TO BE CARRIED ON STRONG NORTHERLY FLOW INTO NEAR LAKE AREAS OF NORTHWEST INDIANA...WHICH WILL LIMIT HIGHS THERE TO THE UPPER 60S. NORTHEAST ILLINOIS MAY SEE A BIT OF A SHADOWING EFFECT TO KEEP CLOUD COVER AT A MINIMUM FOR A TIME...BUT THE LAKESHORE WILL STILL STRUGGLE TO REACH 70 DEGREES. ADDING TO THE FALL-LIKE FEEL WILL BE GUSTY NORTH-NORTHEAST WINDS...STRONGEST NEAR THE LAKEFRONT...THANKS TO A TIGHT PRESSURE GRADIENT AND THE UNSTABLE CONDITIONS OVER THE LAKE. THOSE THAT BRAVE THE COOL CONDITIONS TO HEAD TO THE BEACH WILL BE GREETED BY HIGH WAVES AND DANGEROUS CURRENTS...SO SWIMMING IS STRONGLY DISCOURAGED. TONIGHT...WINDS WILL QUICKLY DIMINISH AS THE HIGH BUILDS IN AND SKIES SHOULD CLEAR FOR MOST AREAS AFTER ANY LINGERING EVENING STRATOCU. THIS WILL SET THE STAGE FOR VERY CHILLY CONDITIONS IN RURAL AND OUTLYING SUBURBAN AREAS WHERE UPPER 40S ARE EXPECTED AND EVEN A FEW MID 40S ARE POSSIBLE. THE CHICAGO HEAT ISLAND WILL DROP TO NEAR 60 DEGREES. THE EXCEPTION TO THE ABOVE WILL BE THE NORTHWEST INDIANA AND POSSIBLY FAR EAST AND SOUTHEAST COOK COUNTY LAKEFRONT...WHERE FAVORABLE LAKE EFFECT CONDITIONS WILL CONTINUE TO EXIST AND RESULTANT CLOUD COVER WILL KEEP TEMPERATURES MILDER. CONSIDERED PUTTING IN A SLIGHT CHANCE POP FOR LAKE EFFECT SHRA BUT HELD OFF AND WILL ALLOW THE DAY SHIFT TO ASSESS...AS THE AIR MASS MOVING OVER THE LAKE IS VERY DRY. ON WEDNESDAY AND BEYOND...INVERSION LEVELS WILL DROP AS MID LEVEL HEIGHTS RISE...SO ANY LAKE EFFECT CLOUDS WILL LIKELY DIMINISH EARLY...BUT EXPECT TO SEE BLOSSOMING CUMULUS AGAIN BY LATE MORNING. 850 MB TEMPERATURES WILL BE CLOSE TO TODAY...BUT 925 MB TEMPS WILL RISE TO SUPPORT A FEW DEGREE RISE IN HIGH TEMPERATURES. THE CONTINUED GRADUAL DEPARTURE OF THE DEEP TROUGH OVER EASTERN CANADA AND THE GREAT LAKES WILL RESULT IN WARMING THERMAL PROFILES ON THURSDAY...SO AFTER ANOTHER CLEAR AND CHILLY NIGHT...SOME LOCATIONS MAY TAG 80 DEGREES. THE SLOW WARMING TREND WILL THEN CONTINUE THROUGH THE WEEKEND INTO EARLY NEXT WEEK...WITH HIGHS IN THE MID 80S OR EVEN WARMER POSSIBLY BY MONDAY. THE SOUTHEASTERN CWA COULD SEE ENOUGH MOISTURE RETURN BEHIND HIGH PRESSURE FINALLY SHIFTING TO THE EAST FOR A LIMITED THREAT FOR TSRA BY MONDAY OR POTENTIALLY AS EARLY AS SUNDAY...BUT OTHERWISE THE DRY PATTERN MOST OF THE AREA HAS BEEN IN SINCE THE BEGINNING OF JULY WILL CONTINUE. RC && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * STRONG/GUSTY NORTH/NORTHEAST WINDS THROUGH EARLY THIS EVENING. CMS //DISCUSSION...UPDATED 18Z... ONLY FORECAST CONCERN THIS PERIOD ARE WINDS. HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL SPREAD SOUTHEAST ACROSS THE AREA OVERNIGHT INTO WEDNESDAY. GUSTY NORTHEASTERLY WINDS WILL CONTINUE THIS AFTERNOON BUT BEGIN TO SLOWLY DIMINISH. POSSIBLE GUSTS WILL DIMINISH PRIOR TO CURRENT END TIME...POSSIBLY AS EARLY AS 22Z- 23Z...ESPECIALLY ACROSS NORTHWEST IL. AS THE HIGH APPROACHES THIS EVENING...WINDS MAY TURN NORTHWESTERLY OR EVEN WESTERLY...BUT AT THAT TIME SPEEDS WILL BE WELL UNDER 10 KTS. WINDS WILL THEN BECOME LIGHT AND VARIABLE OR CALM OVERNIGHT. LIGHT NORTH/NORTHEAST WINDS EXPECTED WEDNESDAY MORNING WITH A LAKE BREEZE TURNING WINDS MORE EASTERLY WEDNESDAY AFTERNOON. CMS //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH FOR WINDS THIS AFTERNOON...MEDIUM FOR THE REST OF THE PERIOD. CMS //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT THROUGH MONDAY...VFR. MDB && .MARINE... 300 AM CDT A SERIES OF COLD FRONTS HAS NOW PUSHED SOUTH OF LAKE MICHIGAN WITH A FAIRLY TIGHT PRESSURE GRADIENT POSITIONED ACROSS THE LAKE WITH LOW PRESSURE TO THE EAST OVER EASTERN ONTARIO AND A STRONG HIGH PRESSURE SYSTEM TO THE WEST FROM MANITOBA ACROSS THE DAKOTAS. NORTH TO NORTHEAST WINDS HAVE INCREASED ACROSS THE LAKE AND WILL REMAIN STRONG THROUGH LATE AFTERNOON AT WHICH POINT SPEEDS WILL BEGIN TO GRADUALLY EASE AS THE PRESSURE GRADIENT SLACKENS. WESTERN AND NORTHERN SECTIONS OF THE LAKE WILL SEE WINDS DIMINISHING FIRST AS THE GRADIENT WILL BE WEAKENING FROM NORTHWEST TO SOUTHEAST. WAVES WILL CONTINUE TO BUILD THIS MORNING WITH THE LONG FETCH DIRECTING THEM AT THE SOUTHERN SHORELINES. HAVE BUMPED WAVES UP TO 5 TO 8 FT WITH OCCASIONAL 12 FT FOR THE SOUTHERN PARTS OF THE LAKE WITH WELL EXPOSED BUOYS NEAR THE END OF THE DEVELOPING FETCH ALREADY SHOWING WAVES IN THE 4 TO 6 FT RANGE...WITH A FEW PEAKS CLOSER TO 7 FT. WILL CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS. THE HIGH WILL MOVE SOUTHWARD AND SETTLE INTO ILLINOIS INTO WEDNESDAY AND THEN GRADUALLY SPREAD EASTWARD ACROSS THE OHIO VALLEY THROUGH THE END OF THE WEEK. NORTHERLY WINDS WILL LIKELY TURN ONSHORE WEDNESDAY WITH THE WEAK PRESSURE GRADIENT IN PLACE BEFORE SHIFTING TO SOUTHERLY ACROSS MOST OF THE LAKE WEDNESDAY NIGHT AS THE HIGH SHIFTS. SOUTHWEST TO WEST WINDS ARE EXPECTED THROUGH THE REMAINDER OF THE WEEK BUT ONSHORE FLOW WILL LIKELY SET UP ACROSS SOUTHERN PARTS OF THE LAKE WHERE THE PRESSURE GRADIENT WILL REMAIN WEAK INTO THE WEEKEND. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014 UNTIL 4 AM WEDNESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 AM WEDNESDAY. LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 7 AM WEDNESDAY. && $$ 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 1148 AM CDT Tue Aug 13 2013 .DISCUSSION... ISSUED 950 AM CDT Tue Aug 13 2013 Large shield of cirrus clouds continues to push eastward this morning, but has been showing some thinning as of late. Have had quite a bit of stratus over the southeast CWA which is a bit stubborn to erode, and a narrow band has also been quickly dropping southwest toward the I-74 corridor as cooler and drier air works its way toward our area. The diurnal cumulus should start forming over the next couple hours, but latest CU-rule off the RAP model diminishes this from north to south as the drier air aloft mixes downward, so sunshine should be on the increase during the afternoon. Have made the usual minor hourly temperature adjustments for today, which generally did not impact the high temperature forecasts. Also refreshed the zone forecasts to remove mention of morning fog in the eastern CWA, although little change was needed otherwise. Geelhart && .AVIATION... ISSUED 1147 AM CDT Tue Aug 13 2013 Narrow band of MVFR ceilings continues to drop southwest as drier air moves into central Illinois. Will see these continue for another hour or two from KSPI-KDEC-KCMI, with diurnal cumulus above 3000 feet forming afterward. Greatest question with ceilings will be at KCMI, where lake-effect clouds continue to stream southward toward the area. Clouds will fade mid to late afternoon in most areas. Mainly clear skies expected tonight into Wednesday morning, as high pressure settles into the mid-Mississippi Valley. Northeast winds will gradually trend more northerly Wednesday morning with the arrival of the high. Geelhart && .PREV DISCUSSION... ISSUED 253 AM CDT Tue Aug 13 2013 SHORT TERM...Today through Thursday 07z/2am surface analysis shows cold front settling southward toward the Ohio River, with bulk of remaining convection now well to the south across far southern Indiana into Kentucky. Despite frontal passage and light northerly flow, air mass remains rather humid across central Illinois. Surface dew points are still in the middle to upper 60s across most of the area, with drier upper 50s beginning to filter into the far north around Galesburg. Due to mostly clear skies and light winds, this lingering low- level moisture is producing some patchy fog around the area. Will include fog mention in the forecast this morning, mainly for locations south of I-72 where moisture will linger longest. After any early morning fog dissipates, mostly sunny and cool weather will be the rule today. Secondary cold front will allow very cool air mass to pour southward into Illinois today, with 850mb temps expected to drop into the 8 to 10C range. Numeric guidance is suggesting highs only in the lower to middle 70s: however, based on upstream readings yesterday afternoon and strength of mid- August sun, think this is too cool. Will go several degrees above guidance, with highs ranging from the middle 70s far north, to the lower 80s along and south of I-70. Clear skies and light winds will allow excellent radiational cooling conditions to develop tonight, resulting in chilly overnight lows in the upper 40s and lower 50s. With high pressure remaining overhead, the cool/dry weather will continue on Wednesday and Thursday as well, with highs in the middle to upper 70s and lows mainly in the 50s. LONG TERM...Friday through Monday Short-wave currently evident on water vapor imagery over Oregon will track up and over the western CONUS ridge and into the Midwest by the end of the week. This feature may trigger scattered showers/thunder across Iowa and Nebraska Thursday night; however, by the time it arrives in the drier air mass across Illinois, am expecting only a slight increase in cloud cover on Friday. The wave will act to amplify the existing long-wave trough in place across the eastern CONUS this weekend into early next week. 00z Aug 13 models continue to suggest the amplifying trough will eventually lead to the development of an inverted surface trough across the Ohio River Valley Sunday/Monday. This is the second straight day models have latched onto this solution, so confidence is growing that disturbed weather may develop to the E/SE early next week. GFS/ECMWF spread a few showers into east- central/southeast Illinois Sunday and Monday, however GEM tends to keep precip a bit further east across Indiana. Will increase cloud cover and carry a slight chance POP east of I-57 accordingly. Air mass will slowly moderate through the period, with high temperatures climbing back into the lower to middle 80s by Sunday. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1050 AM CDT TUE AUG 13 2013 .DISCUSSION... 1050 AM CDT FOR MORNING UPDATE... NO SIGNIFICANT CHANGES TO NEAR TERM FORECAST THIS MORNING. ONLY MINOR TWEAKS TO HOURLY TEMP/SKY COVER GRIDS BASED ON CURRENT OBS AND SATELLITE TRENDS. SPRAWLING CANADIAN SURFACE HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST FROM THE LAKE WINNIPEG AREA OF SOUTHERN MANITOBA LATE THIS MORNING...WITH BREEZY NORTH-NORTHEAST SURFACE WINDS AHEAD OF THE ADVANCING ANTICYCLONE BRINGING COOLER AND DRIER ALMOST EARLY-AUTUMN LIKE AIR TO THE FORECAST AREA. IN FACT...THE COOL AIR ALOFT...WITH +5C SAMPLED AT 850 MB IN THE GREEN BAY WISC 12Z RAOB...HAS LED TO DEVELOPMENT OF LAKE EFFECT STRATOCU ACROSS LAKE MICHIGAN. THIS LAKE INDUCED CLOUD COVER WAS SPREADING INLAND INTO THE CHICAGO METRO AREA DOWNWIND OF THE LAKE. ASSESSMENT OF THE MORNING RAOB DATA AND MODEL LOW-LEVEL THERMAL FIELDS CONTINUES TO INDICATE A RATHER COOL DAY FOR MID-AUGUST...WITH HIGHS RANGING FROM PERHAPS THE UPPER 60S ALONG THE LAKE MICHIGAN SHORE...TO THE LOW-MID 70S IN THE WARMEST INLAND REACHES SUCH AS DIXON/PONTIAC. DEW POINT TEMPS IN THE MID-UPPER 40S WILL MAKE FOR DRY CONDITIONS THIS AFTERNOON AS WELL...AS WINDS BEGIN TO DIMINISH WITH THE GRADIENT GRADUALLY WEAKENING WITH THE APPROACH OF THE HIGH PRESSURE CENTER. RATZER && .PREV DISCUSSION... 327 AM CDT WITH EXPANSIVE SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTHWEST AND THEN ESTABLISHING ITSELF OVER THE GREAT LAKES REGION THROUGH THE WEEKEND...THERE ARE NO REAL WEATHER CONCERNS FOR THE AREA. HOWEVER...AN UNSEASONABLY COOL AIR MASS IS PLUNGING SOUTH DOWN LAKE MICHIGAN BEHIND A SECONDARY COLD FRONT AND SHARP TROUGH AXIS SEEN WELL ON WATER VAPOR IMAGERY EARLY THIS MORNING. THIS WILL QUICKLY TRANSPORT THE MID SINGLE DIGIT 850 MB TEMPS OVER ONTARIO ON THE 00Z RAOB TO OUR AREA BY THIS AFTERNOON...WHICH WILL MAKE FOR MORE FALL-LIKE THAN SUMMER-LIKE HIGH TEMPERATURES PRIMARILY IN THE LOWER 70S...WITH A SCATTERING OF MID 70S READINGS IN THE FAR SOUTH AND WEST. DESPITE A VERY DRY AIRMASS...STEEPENING LOW LEVEL LAPSE RATES AND NEAR SATURATION AT ABOUT 800 MB WILL LIKELY RESULT IN A BLOSSOMING STRATOCU DECK BY MID TO LATE MORNING THAT WILL GRADUALLY DISSIPATE THROUGH THE EVENING. IN ADDITION...FORECAST SOUNDINGS INDICATE FAVORABLE PROFILES FOR GENERATION OF LAKE EFFECT CLOUDS WHICH ARE EXPECTED TO BE CARRIED ON STRONG NORTHERLY FLOW INTO NEAR LAKE AREAS OF NORTHWEST INDIANA...WHICH WILL LIMIT HIGHS THERE TO THE UPPER 60S. NORTHEAST ILLINOIS MAY SEE A BIT OF A SHADOWING EFFECT TO KEEP CLOUD COVER AT A MINIMUM FOR A TIME...BUT THE LAKESHORE WILL STILL STRUGGLE TO REACH 70 DEGREES. ADDING TO THE FALL-LIKE FEEL WILL BE GUSTY NORTH-NORTHEAST WINDS...STRONGEST NEAR THE LAKEFRONT...THANKS TO A TIGHT PRESSURE GRADIENT AND THE UNSTABLE CONDITIONS OVER THE LAKE. THOSE THAT BRAVE THE COOL CONDITIONS TO HEAD TO THE BEACH WILL BE GREETED BY HIGH WAVES AND DANGEROUS CURRENTS...SO SWIMMING IS STRONGLY DISCOURAGED. TONIGHT...WINDS WILL QUICKLY DIMINISH AS THE HIGH BUILDS IN AND SKIES SHOULD CLEAR FOR MOST AREAS AFTER ANY LINGERING EVENING STRATOCU. THIS WILL SET THE STAGE FOR VERY CHILLY CONDITIONS IN RURAL AND OUTLYING SUBURBAN AREAS WHERE UPPER 40S ARE EXPECTED AND EVEN A FEW MID 40S ARE POSSIBLE. THE CHICAGO HEAT ISLAND WILL DROP TO NEAR 60 DEGREES. THE EXCEPTION TO THE ABOVE WILL BE THE NORTHWEST INDIANA AND POSSIBLY FAR EAST AND SOUTHEAST COOK COUNTY LAKEFRONT...WHERE FAVORABLE LAKE EFFECT CONDITIONS WILL CONTINUE TO EXIST AND RESULTANT CLOUD COVER WILL KEEP TEMPERATURES MILDER. CONSIDERED PUTTING IN A SLIGHT CHANCE POP FOR LAKE EFFECT SHRA BUT HELD OFF AND WILL ALLOW THE DAY SHIFT TO ASSESS...AS THE AIR MASS MOVING OVER THE LAKE IS VERY DRY. ON WEDNESDAY AND BEYOND...INVERSION LEVELS WILL DROP AS MID LEVEL HEIGHTS RISE...SO ANY LAKE EFFECT CLOUDS WILL LIKELY DIMINISH EARLY...BUT EXPECT TO SEE BLOSSOMING CUMULUS AGAIN BY LATE MORNING. 850 MB TEMPERATURES WILL BE CLOSE TO TODAY...BUT 925 MB TEMPS WILL RISE TO SUPPORT A FEW DEGREE RISE IN HIGH TEMPERATURES. THE CONTINUED GRADUAL DEPARTURE OF THE DEEP TROUGH OVER EASTERN CANADA AND THE GREAT LAKES WILL RESULT IN WARMING THERMAL PROFILES ON THURSDAY...SO AFTER ANOTHER CLEAR AND CHILLY NIGHT...SOME LOCATIONS MAY TAG 80 DEGREES. THE SLOW WARMING TREND WILL THEN CONTINUE THROUGH THE WEEKEND INTO EARLY NEXT WEEK...WITH HIGHS IN THE MID 80S OR EVEN WARMER POSSIBLY BY MONDAY. THE SOUTHEASTERN CWA COULD SEE ENOUGH MOISTURE RETURN BEHIND HIGH PRESSURE FINALLY SHIFTING TO THE EAST FOR A LIMITED THREAT FOR TSRA BY MONDAY OR POTENTIALLY AS EARLY AS SUNDAY...BUT OTHERWISE THE DRY PATTERN MOST OF THE AREA HAS BEEN IN SINCE THE BEGINNING OF JULY WILL CONTINUE. RC && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * STRONG/GUSTY NORTH/NORTHEAST WINDS THROUGH EARLY THIS EVENING. * HIGH MVFR CIGS POSSIBLE THROUGH LATE MORNING/EARLY AFTERNOON. CMS //DISCUSSION...UPDATED 12Z... TRICKY CLOUD AND WIND FORECAST FOR TERMINALS NEAR LAKE MICHIGAN THIS MORNING. HIGH PRESSURE IS BUILDING IN FROM THE NORTH PROVIDING COOLER AIR AND A NORTHERLY WIND FETCH DOWN LAKE MICHIGAN. THIS HAS ALLOWED MVFR LAKE STRATUS TO DEVELOP AND REACH THE ILLINOIS AND INDIANA SHORELINES. EXPECT THAT ORD/MDW WILL HAVE A PERIOD OF SCT-BKN MVFR CLOUDS THIS MORNING BUT ITS NOT CLEAR HOW LONG THEY WILL LINGER. GYY WILL LIKELY REMAIN BKN THROUGH THE MORNING AND COULD DO SO THROUGH MUCH OF THE AFTERNOON AS WELL. THE OTHER CHALLENGE WILL BE WINDS. LATEST SFC OBS AROUND THE LAKE SUGGEST SOME CONVERGENCE IS SETTING UP ALONG THE WESTERN LAKESHORE AS EVIDENCED BY SHORELINE WINDS TURNING NNW FROM THEIR EARLIER NE DIRECTION. EXPECT THAT A SHIFT TO NNE OR NE WILL OCCUR YET THIS MORNING BUT HAVE LOW CONFIDENCE IN HOW QUICKLY THIS WILL HAPPEN. THIS MAY ALSO SERVE TO KEEP STRATUS IN PLACE AT ORD/MDW LONGER BUT BASES WOULD LIKELY RISE TO LOWER END VFR LEVELS. OTHERWISE AREAS AWAY FROM THE LAKE WILL BE MORE NORTHEASTERLY. HIGH PRESSURE WILL BE JUST ABOUT OVER THE AREA THIS EVENING WHICH WILL ALLOW WINDS TO DIMINISH. LAKE EFFECT PARAMETERS WILL STILL BE FAVORABLE SO WILL NEED TO WATCH CLOUD TRENDS THROUGH THE AFTERNOON BUT EXPECT GYY TO BE THE MAIN TERMINAL AFFECTED WITH LAKE CLOUDS AS LOW/MID LEVEL WINDS WILL BE TURNING A BIT MORE NORTHWESTERLY SUGGESTING ORD/MDW MAY REMAIN WEST OF THE CLOUDS. MDB //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THROUGH THE PERIOD. * MEDIUM FOR MVFR CIGS THIS MORNING. CMS //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT THROUGH MONDAY...VFR. MDB && .MARINE... 300 AM CDT A SERIES OF COLD FRONTS HAS NOW PUSHED SOUTH OF LAKE MICHIGAN WITH A FAIRLY TIGHT PRESSURE GRADIENT POSITIONED ACROSS THE LAKE WITH LOW PRESSURE TO THE EAST OVER EASTERN ONTARIO AND A STRONG HIGH PRESSURE SYSTEM TO THE WEST FROM MANITOBA ACROSS THE DAKOTAS. NORTH TO NORTHEAST WINDS HAVE INCREASED ACROSS THE LAKE AND WILL REMAIN STRONG THROUGH LATE AFTERNOON AT WHICH POINT SPEEDS WILL BEGIN TO GRADUALLY EASE AS THE PRESSURE GRADIENT SLACKENS. WESTERN AND NORTHERN SECTIONS OF THE LAKE WILL SEE WINDS DIMINISHING FIRST AS THE GRADIENT WILL BE WEAKENING FROM NORTHWEST TO SOUTHEAST. WAVES WILL CONTINUE TO BUILD THIS MORNING WITH THE LONG FETCH DIRECTING THEM AT THE SOUTHERN SHORELINES. HAVE BUMPED WAVES UP TO 5 TO 8 FT WITH OCCASIONAL 12 FT FOR THE SOUTHERN PARTS OF THE LAKE WITH WELL EXPOSED BUOYS NEAR THE END OF THE DEVELOPING FETCH ALREADY SHOWING WAVES IN THE 4 TO 6 FT RANGE...WITH A FEW PEAKS CLOSER TO 7 FT. WILL CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS. THE HIGH WILL MOVE SOUTHWARD AND SETTLE INTO ILLINOIS INTO WEDNESDAY AND THEN GRADUALLY SPREAD EASTWARD ACROSS THE OHIO VALLEY THROUGH THE END OF THE WEEK. NORTHERLY WINDS WILL LIKELY TURN ONSHORE WEDNESDAY WITH THE WEAK PRESSURE GRADIENT IN PLACE BEFORE SHIFTING TO SOUTHERLY ACROSS MOST OF THE LAKE WEDNESDAY NIGHT AS THE HIGH SHIFTS. SOUTHWEST TO WEST WINDS ARE EXPECTED THROUGH THE REMAINDER OF THE WEEK BUT ONSHORE FLOW WILL LIKELY SET UP ACROSS SOUTHERN PARTS OF THE LAKE WHERE THE PRESSURE GRADIENT WILL REMAIN WEAK INTO THE WEEKEND. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014 UNTIL 4 AM WEDNESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 AM WEDNESDAY. LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 7 AM WEDNESDAY. && $$ 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 951 AM CDT Tue Aug 13 2013 .DISCUSSION... ISSUED 950 AM CDT Tue Aug 13 2013 Large shield of cirrus clouds continues to push eastward this morning, but has been showing some thinning as of late. Have had quite a bit of stratus over the southeast CWA which is a bit stubborn to erode, and a narrow band has also been quickly dropping southwest toward the I-74 corridor as cooler and drier air works its way toward our area. The diurnal cumulus should start forming over the next couple hours, but latest CU-rule off the RAP model diminishes this from north to south as the drier air aloft mixes downward, so sunshine should be on the increase during the afternoon. Have made the usual minor hourly temperature adjustments for today, which generally did not impact the high temperature forecasts. Also refreshed the zone forecasts to remove mention of morning fog in the eastern CWA, although little change was needed otherwise. Geelhart && .AVIATION... ISSUED 654 AM CDT Tue Aug 13 2013 IFR/MVFR fog will affect CMI through around 14z-15z, then dissipate as dry air above the surface mixes down and surface dew point spreads increase with daytime heating. High pressure will prevail the remaining time of this TAF period, with VFR conditions. Light north winds will become NNE and increase to 10-12kt by late morning. Diurnal clouds may thicken across our eastern areas, partially due to some Lake Michigan moisture affects. Cu rule params show -1 to -3 in that area as well, so we included a BKN040 cloud deck during the day for CMI/BMI. There may be periods of SCT instead of BKN, but we wanted to show the trend. Shimon && .PREV DISCUSSION... ISSUED 253 AM CDT Tue Aug 13 2013 SHORT TERM...Today through Thursday 07z/2am surface analysis shows cold front settling southward toward the Ohio River...with bulk of remaining convection now well to the south across far southern Indiana into Kentucky. Despite frontal passage and light northerly flow, air mass remains rather humid across central Illinois. Surface dew points are still in the middle to upper 60s across most of the area, with drier upper 50s beginning to filter into the far north around Galesburg. Due to mostly clear skies and light winds, this lingering low-level moisture is producing some patchy fog around the area. Will include fog mention in the forecast this morning, mainly for locations south of I-72 where moisture will linger longest. After any early morning fog dissipates, mostly sunny and cool weather will be the rule today. Secondary cold front will allow very cool air mass to pour southward into Illinois today, with 850mb temps expected to drop into the 8 to 10C range. Numeric guidance is suggesting highs only in the lower to middle 70s: however, based on upstream readings yesterday afternoon and strength of mid-August sun, think this is too cool. Will go several degrees above guidance, with highs ranging from the middle 70s far north...to the lower 80s along and south of I-70. Clear skies and light winds will allow excellent radiational cooling conditions to develop tonight, resulting in chilly overnight lows in the upper 40s and lower 50s. With high pressure remaining overhead, the cool/dry weather will continue on Wednesday and Thursday as well, with highs in the middle to upper 70s and lows mainly in the 50s. LONG TERM...Friday through Monday Short-wave currently evident on water vapor imagery over Oregon will track up and over the western CONUS ridge and into the Midwest by the end of the week. This feature may trigger scattered showers/thunder across Iowa and Nebraska Thursday night: however, by the time it arrives in the drier air mass across Illinois, am expecting only a slight increase in cloud cover on Friday. The wave will act to amplify the existing long-wave trough in place across the eastern CONUS this weekend into early next week. 00z Aug 13 models continue to suggest the amplifying trough will eventually lead to the development of an inverted surface trough across the Ohio River Valley Sunday/Monday. This is the second straight day models have latched onto this solution, so confidence is growing that disturbed weather may develop to the E/SE early next week. GFS/ECMWF spread a few showers into east-central/southeast Illinois Sunday and Monday...however GEM tends to keep precip a bit further east across Indiana. Will increase cloud cover and carry a slight chance POP east of I-57 accordingly. Air mass will slowly moderate through the period...with high temperatures climbing back into the lower to middle 80s by Sunday. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
636 PM MDT WED AUG 14 2013 .UPDATE... ISSUED AT 636 PM MDT WED AUG 14 2013 ADJUSTED POPS/SKY FORECAST BASED ON LATEST RADAR TRENDS AND RAP/HRRR. DECREASED POPS ACROSS MOST OF THE CWA THROUGH THE EARLY EVENING...WITH INCREASING CHANCES AFTER 03Z AS ACTIVITY OVER NE COLORADO DROPS SOUTH. STILL NOT SURE HOW FOG WILL PLAY OUT TONIGHT...WITH ANY LINGERING THUNDERSTORMS AND OUTFLOW COMPLICATING FORECAST. WILL KEEP PATCHY FOG MENTION TIED TO THE EAST...HOWEVER MIGHT NEED TO EXPAND IF IT LOOKS LIKE ACTIVITY UPSTREAM WILL FALL APART SOONER THAN GUIDANCE WOULD INDICATE. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 103 PM MDT WED AUG 14 2013 THE AIR MASS OVER THE FORECAST AREA HAS BECOME UNSTABLE WITH MIXED LAYER CAPES AROUND 1000 J/KG. VISIBLE SATELLITE IMAGERY AND RADAR SHOWS STORMS FORMING ON AN OUTFLOW BOUNDARY FROM CONVECTION LAST NIGHT...MAINLY FROM BURLINGTON COLORADO TO SCOTT CITY KANSAS. MID LEVEL SHEAR IS NOT IMPRESSIVE...SO EXPECT THESE STORMS TO PRODUCE HEAVY RAIN AND SMALL HAIL. PARTS OF YUMA AND KIT CARSON COUNTIES RECEIVED HEAVY RAIN LAST NIGHT. CONSIDERED A FLASH FLOOD WATCH FOR THOSE AREAS...BUT 700 MB THETA/E AXIS IS TOO FAR WEST AND A SUBTROPICAL CONNECTION IS NOT APPARENT FROM WATER VAPOR. IF STORMS FORM THERE...HOWEVER...WILL HAVE TO MONITOR FOR FLOODING GIVEN SLOW STORM MOTION. OTHERWISE...WILL KEEP A CHANCE OF CONVECTION OVER THE ENTIRE FORECAST AREA GIVEN THE INSTABILITY. WITH LACK OF DIFFERENTIAL CYCLONIC VORTICITY ADVECTION...CONVECTION WILL END BY 06Z. DEW POINT DEPRESSIONS EAST OF HIGHWAY 83 WILL BE LOW ENOUGH TO ADD PATCHY FOG TO THE FORECAST. THERE IS A BETTER CHANCE FOR SEVERE CONVECTION THURSDAY AFTERNOON AND EVENING. AS 500 MB RIDGE AMPLIFIES OVER THE ROCKY MOUNTAIN STATES..A VORTICITY LOBE WILL MOVE ACROSS THE CENTRAL PLAINS BETWEEN 18Z-00Z. EXPECT BEST LIFT TO BE ACROSS THE EASTERN HALF OF THE REGION WHERE THE 0-6KM SHEAR WILL EXCEED 45 KNOTS. A WEAK FRONT WILL ALSO BE POSITIONED ALONG INTERSTATE 70 PROVIDING SURFACE CONVERGENCE. FINALLY...A 250 MB WIND MAX...THOUGH NOT IMPRESSIVE...WILL EXTEND OVER WESTERN KANSAS. WITH THESE PARAMETERS IN PLACE...SEVERE WEATHER IS LIKELY ESPECIALLY OVER THE SOUTHEAST HALF OF THE FORECAST AREA. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 223 PM MDT WED AUG 14 2013 FORECAST PROBLEMS WILL BE CHANCE OF PRECIPITATION THURSDAY NIGHT... FOG POSSIBILITIES...AND HOW MUCH TO WARM TO MAKE MAXES AS AREA LOOKS TO SEE A DRY PERIOD. SATELLITE SHOWING AN AMPLIFIED PATTERN FROM CENTRAL PACIFIC INTO EASTERN NORTH AMERICA. AREA IS UNDER NORTHWEST FLOW ALOFT WITH A RATHER STRONG SHORTWAVE TROUGH OVER MONTANA. FRONT REMAINS DRAPED TO OUR WEST AND WELL TO THE SOUTH. TO START OUT AT MID LEVELS...THE GFS WAS DOING A LITTLE BETTER THAN THE UKMET OVERALL. ECMWF WAS DOING WELL ON THE TROUGH IN MONTANA. NAM WAS PERFORMING THE WORST. THE SREF WAS DOING SLIGHTLY BETTER THAN THE ECMWF ON THE SURFACE FIELD. THE CANADIAN AND UKMET WERE DOING THE BEST ON THE LOW LEVEL THERMAL FIELD. THURSDAY NIGHT...AS STATED ABOVE...FRONT WILL BE OVER THE AREA. ALSO SHORTWAVE TROUGH IN NORTHWEST FLOW WILL BE MOVING THROUGH. ANALYSIS AND PROGS SHOW THAT A DECENT PV ANOMALY IS ASSOCIATED WITH THIS SHORTWAVE TROUGH. LEFT FRONT QUADRANT STARTS OUT OVER THE WESTERN PORTION OF THE AREA AND WORKS ITS WAY SOUTH AND EAST THROUGH THE NIGHT. BEST LIFT AND INSTABILITY WILL RESIDE ALONG AND TO THE EAST OF THE COLORADO BORDER. PRECIPITATION CHANCES LOOK TO INCREASE THE FURTHER EAST AND SOUTH YOU GO. TO TIERED THE POPS IN THAT FASHION. THUNDERSTORMS SHOULD END NEAR OR SHORTLY AFTER MIDNIGHT. BOUNDARY LAYER RH INCREASES IN THE LATER HALF OF THE NIGHT PER ALL MODEL GUIDANCE. SO WILL INSERT FOG AND INCREASE SKY COVER. OVERNIGHT TEMPERATURES HAVE BEEN ON THE COOL SIDE. SO SIDED WITH THE BETTER PERFORMING AND COOLER GUIDANCE. FRIDAY/FRIDAY NIGHT...FOG AND STRATUS COULD LINGER FOR A SIGNIFICANT AMOUNT OF THE MORNING WITH LIGHT AND VARIABLE WINDS/EASTERLY WINDS/LITTLE MIXING EXPECTED. MID/UPPER LEVEL RIDGE AND DRIER/WARMER MID LEVEL AIR BUILDS INTO THE REGION. THIS WILL KEEP THE AREA DRY. PER COOLER NWP/2 METER FORECASTS/BIAS ADJUSTMENT ON BETTER PERFORMING 850 MB TEMPERATURES...DID LOWER MAXES. HOWEVER...HOW FAST FOG AND STRATUS BURN OFF WILL DETERMINE HOW WARM THE MAXES GET. FOR THE NIGHT...SOUTHERLY WINDS ARE STRONGER...ESPECIALLY IN THE WEST. BOUNDARY LAYER RH PROGS ARE DRIER SO AT THIS TIME WILL LEAVE ANY MENTION OF FOG OUT ALTHOUGH THERE MAY BE PATCHY AROUND. OVERNIGHT LOWS SHOULD BE WARMER ESPECIALLY IN THE WEST WITH THE STRONGER WINDS. LOOKS TO BE COOLER IN THE EAST WITH THE LIGHTER WINDS. SATURDAY...MID/UPPER LEVEL RIDGE CONTINUES TO BUILD INTO THE AREA WITH CONTINUED DRY AND WARMER AIR ALOFT. SO DRY FORECAST CONTINUED. LEE TROUGH STRENGTHENS DURING THE DAY. INCREASING PRESSURE GRADIENT AND 3 HOUR PRESSURE FALLS WOULD INDICATE CONDITIONS NEARING BREEZY. SATURDAY NIGHT THROUGH WEDNESDAY...MID/UPPER LEVEL RIDGE IS STILL IN PLACE BUT THERE ARE DIFFERENCES IN PLACEMENT OF THE AXIS AND AMPLITUDE. ALTHOUGH IT HAS BACKED OFF A LITTLE...THE LATEST ECMWF STILL IS KEEPING THE IDEA OF THE RIDGE BEING DISPLACED TO THE EAST AND FLATTENED BUY A SHORTWAVE TROUGH MOVING IN FROM THE WEST. THE GFS AND CANADIAN PLUS ENSEMBLE OUTPUT KEEP THE IDEA OF A STRONGER RIDGE IN PLACE. DESPITE THOSE DIFFERENCES...THE CANADIAN AND GFS DO INDICATE THE POSSIBILITY OF WEAK SHORTWAVE TROUGHS COMING ACROSS THE TOP OF THE RIDGE IN THE WEAK FLOW ALOFT. THE CRH_INIT GRIDS GIVE ME A SLIGHT CHANCE TO LOW CHANCE OF PRECIPITATION BEGINNING ON SUNDAY NIGHT. DETERMINISTIC QPF IS LOW WITH THE GEFS PROBABILITIES SUPPORTING THIS SAME POSSIBILITY. BELIEVE THE ECMWF IS TOO AGGRESSIVE WITH ITS SOLUTION. HOWEVER...BECAUSE OF THE WHAT THE DETERMINISTIC AND ENSEMBLE OUTPUT IS SHOWING...THE INIT GRIDS LOOK REASONABLE AND FIT WITH CLIMATOLOGY AS WELL AND WILL NOT CHANGE THEM. TEMPERATURE OUTPUT IS ALSO REASONABLE AND FITS WITH CLIMATOLOGY AS WELL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 513 PM MDT WED AUG 14 2013 CURRENTLY MONITORING ISO-SCT THUNDERSTORM ACTIVITY...WITH SEVERAL STORMS NEARING VICINITY OF BOTH KGLD AND KMCK TERMINALS. WENT AHEAD AND ADDED VCTS GROUPS THROUGH 03Z...AND WILL CONTINUE TO MONITOR TRENDS FOR POTENTIAL IMPACT AT TERMINALS. SHORT RANGE GUIDANCE GENERALLY SUPPORTS THIS ACTIVITY SHIFTING SOUTH AND EAST OF THE TERMINALS AROUND 03Z...THOUGH LATEST HRRR DOES SHOW AN ADDITIONAL THUNDERSTORM COMPLEX OVER NORTHERN COLORADO DROPPING SOUTH AFTER 06Z. NOT A LOT OF CONFIDENCE YET IN THIS LATE NIGHT CONVECTION SO I LEFT MENTION OUT FOR NOW. GUIDANCE CONTINUES TO SHOW FOG/STRATUS DEVELOPMENT...AND AS LONG AS THUNDERSTORM/MID LEVEL CLOUDS CLEAR WE SHOULD SEE FAVORABLE CONDITIONS FOR THIS. NAM/MET STILL FAVORS EASTERN LOCATIONS REACHING LIFR CONDITIONS BY 12Z (INCLUDING KMCK). LATEST SHORT RANGE GUIDANCE IS HINTING AT WESTERN DEVELOPMENT OF THESE LOWER CONDITIONS AS WELL...SO I CANT RULE OUT IFR/LIFR AT KGLD. WILL WAIT AND SEE HOW THIS EVENINGS THUNDERSTORM ACTIVITY TRENDS BEFORE MAKING LOWER CONDITIONS PREVAILING AT EITHER TERMINAL...SINCE THIS COULD LIMIT FOG DEVELOPMENT LIKE LAST NIGHT. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...MENTZER LONG TERM...BULLER AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
513 PM MDT WED AUG 14 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 103 PM MDT WED AUG 14 2013 THE AIR MASS OVER THE FORECAST AREA HAS BECOME UNSTABLE WITH MIXED LAYER CAPES AROUND 1000 J/KG. VISIBLE SATELLITE IMAGERY AND RADAR SHOWS STORMS FORMING ON AN OUTFLOW BOUNDARY FROM CONVECTION LAST NIGHT...MAINLY FROM BURLINGTON COLORADO TO SCOTT CITY KANSAS. MID LEVEL SHEAR IS NOT IMPRESSIVE...SO EXPECT THESE STORMS TO PRODUCE HEAVY RAIN AND SMALL HAIL. PARTS OF YUMA AND KIT CARSON COUNTIES RECEIVED HEAVY RAIN LAST NIGHT. CONSIDERED A FLASH FLOOD WATCH FOR THOSE AREAS...BUT 700 MB THETA/E AXIS IS TOO FAR WEST AND A SUBTROPICAL CONNECTION IS NOT APPARENT FROM WATER VAPOR. IF STORMS FORM THERE...HOWEVER...WILL HAVE TO MONITOR FOR FLOODING GIVEN SLOW STORM MOTION. OTHERWISE...WILL KEEP A CHANCE OF CONVECTION OVER THE ENTIRE FORECAST AREA GIVEN THE INSTABILITY. WITH LACK OF DIFFERENTIAL CYCLONIC VORTICITY ADVECTION...CONVECTION WILL END BY 06Z. DEW POINT DEPRESSIONS EAST OF HIGHWAY 83 WILL BE LOW ENOUGH TO ADD PATCHY FOG TO THE FORECAST. THERE IS A BETTER CHANCE FOR SEVERE CONVECTION THURSDAY AFTERNOON AND EVENING. AS 500 MB RIDGE AMPLIFIES OVER THE ROCKY MOUNTAIN STATES..A VORTICITY LOBE WILL MOVE ACROSS THE CENTRAL PLAINS BETWEEN 18Z-00Z. EXPECT BEST LIFT TO BE ACROSS THE EASTERN HALF OF THE REGION WHERE THE 0-6KM SHEAR WILL EXCEED 45 KNOTS. A WEAK FRONT WILL ALSO BE POSITIONED ALONG INTERSTATE 70 PROVIDING SURFACE CONVERGENCE. FINALLY...A 250 MB WIND MAX...THOUGH NOT IMPRESSIVE...WILL EXTEND OVER WESTERN KANSAS. WITH THESE PARAMETERS IN PLACE...SEVERE WEATHER IS LIKELY ESPECIALLY OVER THE SOUTHEAST HALF OF THE FORECAST AREA. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 223 PM MDT WED AUG 14 2013 FORECAST PROBLEMS WILL BE CHANCE OF PRECIPITATION THURSDAY NIGHT... FOG POSSIBILITIES...AND HOW MUCH TO WARM TO MAKE MAXES AS AREA LOOKS TO SEE A DRY PERIOD. SATELLITE SHOWING AN AMPLIFIED PATTERN FROM CENTRAL PACIFIC INTO EASTERN NORTH AMERICA. AREA IS UNDER NORTHWEST FLOW ALOFT WITH A RATHER STRONG SHORTWAVE TROUGH OVER MONTANA. FRONT REMAINS DRAPED TO OUR WEST AND WELL TO THE SOUTH. TO START OUT AT MID LEVELS...THE GFS WAS DOING A LITTLE BETTER THAN THE UKMET OVERALL. ECMWF WAS DOING WELL ON THE TROUGH IN MONTANA. NAM WAS PERFORMING THE WORST. THE SREF WAS DOING SLIGHTLY BETTER THAN THE ECMWF ON THE SURFACE FIELD. THE CANADIAN AND UKMET WERE DOING THE BEST ON THE LOW LEVEL THERMAL FIELD. THURSDAY NIGHT...AS STATED ABOVE...FRONT WILL BE OVER THE AREA. ALSO SHORTWAVE TROUGH IN NORTHWEST FLOW WILL BE MOVING THROUGH. ANALYSIS AND PROGS SHOW THAT A DECENT PV ANOMALY IS ASSOCIATED WITH THIS SHORTWAVE TROUGH. LEFT FRONT QUADRANT STARTS OUT OVER THE WESTERN PORTION OF THE AREA AND WORKS ITS WAY SOUTH AND EAST THROUGH THE NIGHT. BEST LIFT AND INSTABILITY WILL RESIDE ALONG AND TO THE EAST OF THE COLORADO BORDER. PRECIPITATION CHANCES LOOK TO INCREASE THE FURTHER EAST AND SOUTH YOU GO. TO TIERED THE POPS IN THAT FASHION. THUNDERSTORMS SHOULD END NEAR OR SHORTLY AFTER MIDNIGHT. BOUNDARY LAYER RH INCREASES IN THE LATER HALF OF THE NIGHT PER ALL MODEL GUIDANCE. SO WILL INSERT FOG AND INCREASE SKY COVER. OVERNIGHT TEMPERATURES HAVE BEEN ON THE COOL SIDE. SO SIDED WITH THE BETTER PERFORMING AND COOLER GUIDANCE. FRIDAY/FRIDAY NIGHT...FOG AND STRATUS COULD LINGER FOR A SIGNIFICANT AMOUNT OF THE MORNING WITH LIGHT AND VARIABLE WINDS/EASTERLY WINDS/LITTLE MIXING EXPECTED. MID/UPPER LEVEL RIDGE AND DRIER/WARMER MID LEVEL AIR BUILDS INTO THE REGION. THIS WILL KEEP THE AREA DRY. PER COOLER NWP/2 METER FORECASTS/BIAS ADJUSTMENT ON BETTER PERFORMING 850 MB TEMPERATURES...DID LOWER MAXES. HOWEVER...HOW FAST FOG AND STRATUS BURN OFF WILL DETERMINE HOW WARM THE MAXES GET. FOR THE NIGHT...SOUTHERLY WINDS ARE STRONGER...ESPECIALLY IN THE WEST. BOUNDARY LAYER RH PROGS ARE DRIER SO AT THIS TIME WILL LEAVE ANY MENTION OF FOG OUT ALTHOUGH THERE MAY BE PATCHY AROUND. OVERNIGHT LOWS SHOULD BE WARMER ESPECIALLY IN THE WEST WITH THE STRONGER WINDS. LOOKS TO BE COOLER IN THE EAST WITH THE LIGHTER WINDS. SATURDAY...MID/UPPER LEVEL RIDGE CONTINUES TO BUILD INTO THE AREA WITH CONTINUED DRY AND WARMER AIR ALOFT. SO DRY FORECAST CONTINUED. LEE TROUGH STRENGTHENS DURING THE DAY. INCREASING PRESSURE GRADIENT AND 3 HOUR PRESSURE FALLS WOULD INDICATE CONDITIONS NEARING BREEZY. SATURDAY NIGHT THROUGH WEDNESDAY...MID/UPPER LEVEL RIDGE IS STILL IN PLACE BUT THERE ARE DIFFERENCES IN PLACEMENT OF THE AXIS AND AMPLITUDE. ALTHOUGH IT HAS BACKED OFF A LITTLE...THE LATEST ECMWF STILL IS KEEPING THE IDEA OF THE RIDGE BEING DISPLACED TO THE EAST AND FLATTENED BUY A SHORTWAVE TROUGH MOVING IN FROM THE WEST. THE GFS AND CANADIAN PLUS ENSEMBLE OUTPUT KEEP THE IDEA OF A STRONGER RIDGE IN PLACE. DESPITE THOSE DIFFERENCES...THE CANADIAN AND GFS DO INDICATE THE POSSIBILITY OF WEAK SHORTWAVE TROUGHS COMING ACROSS THE TOP OF THE RIDGE IN THE WEAK FLOW ALOFT. THE CRH_INIT GRIDS GIVE ME A SLIGHT CHANCE TO LOW CHANCE OF PRECIPITATION BEGINNING ON SUNDAY NIGHT. DETERMINISTIC QPF IS LOW WITH THE GEFS PROBABILITIES SUPPORTING THIS SAME POSSIBILITY. BELIEVE THE ECMWF IS TOO AGGRESSIVE WITH ITS SOLUTION. HOWEVER...BECAUSE OF THE WHAT THE DETERMINISTIC AND ENSEMBLE OUTPUT IS SHOWING...THE INIT GRIDS LOOK REASONABLE AND FIT WITH CLIMATOLOGY AS WELL AND WILL NOT CHANGE THEM. TEMPERATURE OUTPUT IS ALSO REASONABLE AND FITS WITH CLIMATOLOGY AS WELL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 513 PM MDT WED AUG 14 2013 CURRENTLY MONITORING ISOL-SCT THUNDERSTORM ACTIVITY...WITH SEVERAL STORMS NEARING VICINITY OF BOTH KGLD AND KMCK TERMINALS. WENT AHEAD AND ADDED VCTS GROUPS THROUGH 03Z...AND WILL CONTINUE TO MONITOR TRENDS FOR POTENTIAL IMPACT AT TERMINALS. SHORT RANGE GUIDANCE GENERALLY SUPPORTS THIS ACTIVITY SHIFTING SOUTH AND EAST OF THE TERMINALS AROUND 03Z...THOUGH LATEST HRRR DOES SHOW AN ADDITIONAL THUNDERSTORM COMPLEX OVER NORTHERN COLORADO DROPPING SOUTH AFTER 06Z. NOT A LOT OF CONFIDENCE YET IN THIS LATE NIGHT CONVECTION SO I LEFT MENTION OUT FOR NOW. GUIDANCE CONTINUES TO SHOW FOG/STRATUS DEVELOPMENT...AND AS LONG AS THUNDERSTORM/MID LEVEL CLOUDS CLEAR WE SHOULD SEE FAVORABLE CONDITIONS FOR THIS. NAM/MET STILL FAVORS EASTERN LOCATIONS REACHING LIFR CONDITIONS BY 12Z (INCLUDING KMCK). LATEST SHORT RANGE GUIDANCE IS HINTING AT WESTERN DEVELOPMENT OF THESE LOWER CONDITIONS AS WELL...SO I CANT RULE OUT IFR/LIFR AT KGLD. WILL WAIT AND SEE HOW THIS EVENINGS THUNDERSTORM ACTIVITY TRENDS BEFORE MAKING LOWER CONDITIONS PREVAILING AT EITHER TERMINAL...SINCE THIS COULD LIMIT FOG DEVELOPMENT LIKE LAST NIGHT. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...MENTZER LONG TERM...BULLER AVIATION...DR
AREA FORECAST DISCUSSION
NWS TOPEKA KS
328 PM CDT Tue Aug 13 2013 .SHORT TERM...(This Evening through Wednesday) Issued at 328 PM CDT TUE AUG 13 2013 Upper trough remains over the Great Lakes with a shortwave trough extending southwestward into eastern Nebraska. This shortwave along with a well defined MCV in southern Nebraska helped sustain a cluster of showers and thunderstorms into the far northwest corner of the CWA this afternoon. However...a drier and more stable atmosphere over most of the CWA has aided a weakening trend to the convection and expect any sustained or additional development to occur in the western or far southern CWA until early evening. At that time...feel majority of convection...now occurring in central KS will have advanced further south of the vicinity with the outflow boundary...similar to the HRRR model. Will therefore carry a dry forecast for the overnight. Skies may become mostly clear tonight which would support the possibility of some patchy fog. However...feel the potential for more high clouds to advance into the area from the northwest is high enough to negate mentioning fog for now. The dry air and breaks in the clouds should help lows fall into the lower 60s. On Wednesday...will maintain a dry CST as the deeper moisture and axis of higher instability are pushed more to the west of the CWA. Any convection through the day should remain to the west and north of the CWA. High temperatures Wednesday will be similar today...except slightly warmer in the north central with readings in the lower 80s. .LONG TERM...(Wednesday Night through Tuesday) Issued at 328 PM CDT TUE AUG 13 2013 For Wednesday night through Friday, the models have trended more along the lines of the NAM with keeping much of the cooler and dryer air to the northeast of the forecast area. On top of that instead of a distinct shortwave trough moving through the northwest flow Thursday night, models have trended towards bringing several vort maximum through the flow late Wednesday night through Friday. Because of this have trended min temps warmer expecting more cloud cover and higher dewpoint temps through the night. Will also carry a 20 to 30 percent chance pops through the period. Forecast soundings with the higher dewpoints show much less inhibition to convection with lower LCL heights. because of this it is difficult to rule out precip chances with the expected vort energy moving overhead. The airmass in general does not change much from today. Therefore expect temps to be relatively persistent with highs around 80 and lows in the lower to mid 60s. Saturday into Monday is expected to be dry with a gradual warming trend as mid level ridging moves in from the west and insolation increases. Uncertainty remains in the forecast for next week as the ECMWF has shown little consistency from run to run over the last 48 hrs. Think that there will be a small chance for precip Monday night and Tuesday as the GFS continues to bring a shortwave trough across the plains. However confidence is not high since the ECMWF goes back and forth between cutting off an upper low and an open shortwave. && .AVIATION...(For the 18Z TAFs through 18Z Wednesday Afternoon) Issued at 1239 PM CDT TUE AUG 13 2013 Still expect VFR conditions to persist through the forecast as convection expected to remain west and south of the terminals through the period. Could see possible fog tonight...but forecast for high clouds in the area makes confidence in fog potential low...so will therefore not introduce into at this time. east to northeast winds will persist generally under 10 kts...but should slowly veer beyond 12z. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...63 LONG TERM...Wolters AVIATION...63
AREA FORECAST DISCUSSION...UPDATED
NWS TOPEKA KS
1243 PM CDT Tue Aug 13 2013 .UPDATE... Issued at 724 AM CDT TUE AUG 13 2013 The thunderstorm complex over central Nebraska continues to build toward the south southeast this morning. In the past hour, a segment of this complex began to forward propagate with more of a southeasterly direction. Instability is limited but does exist along the highway 81 corridor, and recent RAP runs suggest that it may increase to around 1000 J/Kg by mid morning. This would suggest at least some potential for the system to maintain itself into parts of north central Kansas. Have increased precip chances to around 40 percent, but still see potential for the complex to weaken, remain west of the forecast area, or even fall apart before getting very far into Kansas. Will watch closely as it evolves now that the sun has risen and instability may or may not increase. Barjenbruch && .SHORT TERM...(Today and Tonight) Issued at 324 AM CDT TUE AUG 13 2013 A ridge of surface high pressure had worked its way into northern Kansas early this morning, bringing with it a rather stable airmass. While yet another short wave trough was moving east across southern Kansas this morning, thunderstorm activity has been confined south of the forecast area. Between 2 and 4 AM, the thunderstorm complex has attempted to make a run to the northeast as it pushed out weak outflow, and has come close to Dickinson and Morris counties, but the airmass just seems to increase in stability to the north and the forecast area has remained dry thus far. Another short wave trough of interest, well defined in water vapor imagery, was diving south out of the Dakotas and has aided in development of a thunderstorm complex over north central Nebraska. This morning, there is still some small chance for the complex over southern Kansas to send a few storms into the far southern parts of the forecast area, and have maintained small chances for thunderstorms in these areas accordingly. This potential may even linger into the early afternoon hours as the center of the short wave passes over eastern Kansas. The activity over Nebraska is forecast to track generally to the south with the bulk of convection favored on the western flank where it has greater instability to work with. This should keep this system west of the forecast area, but included a slight chance for precip generally near and west of Highway 81 in case it should clip the area. Temperatures will be similar to, or even a bit cooler than Monday with highs in the lower 80s. Kept the forecast for tonight dry as the surface high would seem to maintain a hold on the area with a stable airmass, and the stronger deep forcing and upper support looks to remain south and west of the forecast area. Barjenbruch .LONG TERM...(Wednesday through Monday) Issued at 324 AM CDT TUE AUG 13 2013 On Wednesday, expansive area of surface high pressure centered over the Mississippi Valley begins to shift eastward leaving another dry and pleasant day for the area. Edged high temperatures during the afternoon into the lower 80s with weak low level winds and peaks of sunshine expected by the late afternoon period. Focus returns to the northwest flow aloft on Thursday as another wave is progged to deepen as it enters the northern plains and dives southeast. The recent runs of the NAM, GFS, and ECWMF have varying timing and intensity differences with the GFS being the most amplified of the group. Almost all solutions have agreed on slight chances of sct thunderstorms developing ahead of the trough on Thursday afternoon over north central KS. Otherwise was not confident to increase rain chances Thursday evening as the main piece of energy may center just north or east of the area. Continued the trend from the afternoon package by assuming increasing cloud cover could leave highs Thursday near the 80 degree mark. Depending on timing with the main upper level system could still see some lingering showers and thunderstorms Friday afternoon especially over east central and northeast portions of KS. Models are beginning to trend subsidence filling in behind the wave which would bring dry conditions over north central areas. Will see if this trend continues in upcoming days. Looking at the extended period, the weekend continues to look dry and pleasantly warm as the upper ridge builds into the plains region. With the weak flow pattern in place, highs in the low 80s and lows near 60 degrees still appear to be reasonable. Another shortwave trough entering over the Pacific Northwest suppresses the ridge as it shifts into the plains region as we head into Monday. Continued with a dry forecast at this time as low confidence exists in timing and how deep the wave is progged to be. Temperatures will greatly depend on the scenario with highs at this time trying to rise closer to normal values in the middle 80s and lows in the 60s. && .AVIATION...(For the 18Z TAFs through 18Z Wednesday Afternoon) Issued at 1239 PM CDT TUE AUG 13 2013 Still expect VFR conditions to persist through the forecast as convection expected to remain west and south of the terminals through the period. Could see possible fog tonight...but fcst for high clouds in the area makes confidence in fog potential low...so will therefore not introduce into at this time. east to northeast winds will persist generally under 10 kts...but should slowly veer beyond 12z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barjenbruch SHORT TERM...Barjenbruch LONG TERM...Bowen AVIATION...63
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
1217 PM CDT Tue Aug 13 2013 ...Updated for Aviation... .SYNOPSIS... ISSUED AT 332 AM CDT TUE AUG 13 2013 During the overnight hours, the heavy rain threat shifted into central and south-central Kansas while much of southwest Kansas was beginning to dry out. The longwave trough continued across eastern Canada into the Great Lakes region...with a reinforcing shortwave trough digging down into the Great Lakes. This shortwave disturbance lead to the frontal passage across Kansas on Monday leading to the evening and late night precipitation event. A mid-upper ridge was found across the northern Rockies, but it was not very substantial ridging and and there were even thunderstorm clusters across eastern Montana within the ridge axis. A 70-80kt 250mb jet also contributed to the organization of last evening`s precipitation event with the upper jet extending from near Las Vegas, NV to central Colorado into eastern Kansas/Nebraska. && .SHORT TERM...(Today and tonight) ISSUED AT 332 AM CDT TUE AUG 13 2013 Main changes in the forecast were lowering the high temperature for today given the likelihood of cloud cover remaining over much of the region. NAM12 and RAP models suggest that clouds will certainly hang in tough for much of the day (especially the RAP model). 700mb temperatures will be cooler today from +6 to +8C with 850mb temps +16 to +18C, so with clouds hanging tough and cooler lower tropospheric temperatures shown by the NAM, RAP, GFS...it is difficult to see afternoon temperatures getting much above the mid to upper 70s. Any sunshine in the afternoon, though, will lead to destabilization and the regeneration of thunderstorms. The strong upper tropospheric jet will remain across Colorado and southern Kansas, so the perturbed mid-upper level flow across the central High Plains will also aid in additional thunderstorm development late in the day. The most likely location for afternoon thunderstorm development will be across eastern Colorado and far western Kansas...farther removed from the influence of last night`s mesoscale convective system (MCS) and the remnant bubble surface high left in its wake. Any new thunderstorms this afternoon may evolve into one or more MCSs, however the best chance at this will be late in the evening and generally west of a Lakin to Liberal line. .LONG TERM...(Wednesday through Monday) ISSUED AT 420 AM CDT TUE AUG 13 2013 Wednesday: A 70 kt 250 hPa jet streak will traverse across western Kansas through the day. At the sfc, an upslope flow regime is expected with weak 850 hPa warm air advection/theta-e advection across far western Kansas. For spatiotemporal adjustments of precipitation probability percentage points, have relied heavily on ECMWF output solutions. Wednesday is shaping up to be another MCS day. Orographic convection is expected to form across the high plains and then drift southeast across the region during the late evening and overnight period. The precipitation numerical values are still in the chance category. The NAM solution is still dry for the most part - but this model has failed with the MCS events recently, so I remain dubious of any described solution herein. The tail end of both WRF cores also support more confidence in the ECMWF solution. Heavy rain will be possible again as precipitable water values are forecast around the 75th percentile for a Gaussian distribution. Otherwise, maximums will be cool because of all the cloud cover and lack of low level downslope flow. Followed the ECE for guidance, which shows values in the upper 70sF to around 80F. Minimums into Thursday morning will be in the lower 60sF. Thursday: Another MCS day is possible Thursday. Upper level flow is more NW during this period as a result the amplification of 500 hPa ridging across the spine of the Rockies. This flow may advect any MCS activity farther east than compared to the previous day. Heavy rain could be a possibility again, as pwats continue on the higher end of the distribution spectrum. Maximum surface temperatures could be a few degrees (F) warmer, particularly across the western zones, as the 850 hPa warm plume advects slightly farther east. A gradient of upper 80sF to around 80F is expected from the west to the east with lows in the 60sF. Friday and beyond: Stuck with the weighted model solution (allblend) for the rest of the forecast period as uncertainty continues to increase. There could be some late afternoon and evening convection across the eastern zones in association with an enhanced region of 850 hPa frontogenesis that the ECMWF solutions shows on Friday. A drier forecast is possible next weekend as the aforementioned 500 hPa ridge amplifies and expands farther east across the region with a net result of drier northerly flow aloft and higher mid level geopotential heights. Temperatures will moderate to near normal during this drier period. Another period of convection is possible in about a week from now as a trof moves across the northern prairies. Will continue to tread lightly. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 1205 PM CDT TUE AUG 13 2013 As a shortwave trough moves southeastward across south central Kansas this afternoon, areas of showers and thunderstorms in the Hays vicinity will move toward KGCK and KDDC by 22z. By 00z expect the thunderstorm activity to decrease as the shortwave trough moves east and south. && .PRELIMINARY POINT TEMPS/POPS... DDC 78 59 80 61 / 40 40 30 40 GCK 77 60 78 62 / 30 30 30 40 EHA 83 60 81 62 / 30 40 40 40 LBL 82 61 80 63 / 30 30 30 40 HYS 76 60 78 60 / 60 30 30 40 P28 78 62 81 64 / 50 60 10 30 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...UMSCHEID SHORT TERM...UMSCHEID LONG TERM...Sugden AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS TOPEKA KS
739 AM CDT Tue Aug 13 2013 .UPDATE... Issued at 724 AM CDT TUE AUG 13 2013 The thunderstorm complex over central Nebraska continues to build toward the south southeast this morning. In the past hour, a segment of this complex began to forward propagate with more of a southeasterly direction. Instability is limited but does exist along the highway 81 corridor, and recent RAP runs suggest that it may increase to around 1000 J/Kg by mid morning. This would suggest at least some potential for the system to maintain itself into parts of north central Kansas. Have increased precip chances to around 40 percent, but still see potential for the complex to weaken, remain west of the forecast area, or even fall apart before getting very far into Kansas. Will watch closely as it evolves now that the sun has risen and instability may or may not increase. Barjenbruch && .SHORT TERM...(Today and Tonight) Issued at 324 AM CDT TUE AUG 13 2013 A ridge of surface high pressure had worked its way into northern Kansas early this morning, bringing with it a rather stable airmass. While yet another short wave trough was moving east across southern Kansas this morning, thunderstorm activity has been confined south of the forecast area. Between 2 and 4 AM, the thunderstorm complex has attempted to make a run to the northeast as it pushed out weak outflow, and has come close to Dickinson and Morris counties, but the airmass just seems to increase in stability to the north and the forecast area has remained dry thus far. Another short wave trough of interest, well defined in water vapor imagery, was diving south out of the Dakotas and has aided in development of a thunderstorm complex over north central Nebraska. This morning, there is still some small chance for the complex over southern Kansas to send a few storms into the far southern parts of the forecast area, and have maintained small chances for thunderstorms in these areas accordingly. This potential may even linger into the early afternoon hours as the center of the short wave passes over eastern Kansas. The activity over Nebraska is forecast to track generally to the south with the bulk of convection favored on the western flank where it has greater instability to work with. This should keep this system west of the forecast area, but included a slight chance for precip generally near and west of Highway 81 in case it should clip the area. Temperatures will be similar to, or even a bit cooler than Monday with highs in the lower 80s. Kept the forecast for tonight dry as the surface high would seem to maintain a hold on the area with a stable airmass, and the stronger deep forcing and upper support looks to remain south and west of the forecast area. Barjenbruch .LONG TERM...(Wednesday through Monday) Issued at 324 AM CDT TUE AUG 13 2013 On Wednesday, expansive area of surface high pressure centered over the Mississippi Valley begins to shift eastward leaving another dry and pleasant day for the area. Edged high temperatures during the afternoon into the lower 80s with weak low level winds and peaks of sunshine expected by the late afternoon period. Focus returns to the northwest flow aloft on Thursday as another wave is progged to deepen as it enters the northern plains and dives southeast. The recent runs of the NAM, GFS, and ECWMF have varying timing and intensity differences with the GFS being the most amplified of the group. Almost all solutions have agreed on slight chances of sct thunderstorms developing ahead of the trough on Thursday afternoon over north central KS. Otherwise was not confident to increase rain chances Thursday evening as the main piece of energy may center just north or east of the area. Continued the trend from the afternoon package by assuming increasing cloud cover could leave highs Thursday near the 80 degree mark. Depending on timing with the main upper level system could still see some lingering showers and thunderstorms Friday afternoon especially over east central and northeast portions of KS. Models are beginning to trend subsidence filling in behind the wave which would bring dry conditions over north central areas. Will see if this trend continues in upcoming days. Looking at the extended period, the weekend continues to look dry and pleasantly warm as the upper ridge builds into the plains region. With the weak flow pattern in place, highs in the low 80s and lows near 60 degrees still appear to be reasonable. Another shortwave trough entering over the Pacific Northwest suppresses the ridge as it shifts into the plains region as we head into Monday. Continued with a dry forecast at this time as low confidence exists in timing and how deep the wave is progged to be. Temperatures will greatly depend on the scenario with highs at this time trying to rise closer to normal values in the middle 80s and lows in the 60s. && .AVIATION...(For the 12Z TAFs through 12Z Wednesday Morning) Issued at 621 AM CDT TUE AUG 13 2013 VFR conditions are forecast through the TAF period with light northeast winds. The only uncertainty would be in some small potential for vis restrictions after 06Z as shallow fog may develop. Barjenbruch && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barjenbruch SHORT TERM...Barjenbruch LONG TERM...Bowen AVIATION...Barjenbruch
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
600 AM CDT Tue Aug 13 2013 ...Update to aviation for 12Z TAFs... .SYNOPSIS... ISSUED AT 332 AM CDT TUE AUG 13 2013 During the overnight hours, the heavy rain threat shifted into central and south-central Kansas while much of southwest Kansas was beginning to dry out. The longwave trough continued across eastern Canada into the Great Lakes region...with a reinforcing shortwave trough digging down into the Great Lakes. This shortwave disturbance lead to the frontal passage across Kansas on Monday leading to the evening and late night precipitation event. A mid-upper ridge was found across the northern Rockies, but it was not very substantial ridging and and there were even thunderstorm clusters across eastern Montana within the ridge axis. A 70-80kt 250mb jet also contributed to the organization of last evening`s precipitation event with the upper jet extending from near Las Vegas, NV to central Colorado into eastern Kansas/Nebraska. && .SHORT TERM...(Today and tonight) ISSUED AT 332 AM CDT TUE AUG 13 2013 Main changes in the forecast were lowering the high temperature for today given the likelihood of cloud cover remaining over much of the region. NAM12 and RAP models suggest that clouds will certainly hang in tough for much of the day (especially the RAP model). 700mb temperatures will be cooler today from +6 to +8C with 850mb temps +16 to +18C, so with clouds hanging tough and cooler lower tropospheric temperatures shown by the NAM, RAP, GFS...it is difficult to see afternoon temperatures getting much above the mid to upper 70s. Any sunshine in the afternoon, though, will lead to destabilization and the regeneration of thunderstorms. The strong upper tropospheric jet will remain across Colorado and southern Kansas, so the perturbed mid-upper level flow across the central High Plains will also aid in additional thunderstorm development late in the day. The most likely location for afternoon thunderstorm development will be across eastern Colorado and far western Kansas...farther removed from the influence of last night`s mesoscale convective system (MCS) and the remnant bubble surface high left in its wake. Any new thunderstorms this afternoon may evolve into one or more MCSs, however the best chance at this will be late in the evening and generally west of a Lakin to Liberal line. .LONG TERM...(Wednesday through Monday) ISSUED AT 420 AM CDT TUE AUG 13 2013 Wednesday: A 70 kt 250 hPa jet streak will traverse across western Kansas through the day. At the sfc, an upslope flow regime is expected with weak 850 hPa warm air advection/theta-e advection across far western Kansas. For spatiotemporal adjustments of precipitation probability percentage points, have relied heavily on ECMWF output solutions. Wednesday is shaping up to be another MCS day. Orographic convection is expected to form across the high plains and then drift southeast across the region during the late evening and overnight period. The precipitation numerical values are still in the chance category. The NAM solution is still dry for the most part - but this model has failed with the MCS events recently, so I remain dubious of any described solution herein. The tail end of both WRF cores also support more confidence in the ECMWF solution. Heavy rain will be possible again as precipitable water values are forecast around the 75th percentile for a Gaussian distribution. Otherwise, maximums will be cool because of all the cloud cover and lack of low level downslope flow. Followed the ECE for guidance, which shows values in the upper 70sF to around 80F. Minimums into Thursday morning will be in the lower 60sF. Thursday: Another MCS day is possible Thursday. Upper level flow is more NW during this period as a result the amplification of 500 hPa ridging across the spine of the Rockies. This flow may advect any MCS activity farther east than compared to the previous day. Heavy rain could be a possibility again, as pwats continue on the higher end of the distribution spectrum. Maximum surface temperatures could be a few degrees (F) warmer, particularly across the western zones, as the 850 hPa warm plume advects slightly farther east. A gradient of upper 80sF to around 80F is expected from the west to the east with lows in the 60sF. Friday and beyond: Stuck with the weighted model solution (allblend) for the rest of the forecast period as uncertainty continues to increase. There could be some late afternoon and evening convection across the eastern zones in association with an enhanced region of 850 hPa frontogenesis that the ECMWF solutions shows on Friday. A drier forecast is possible next weekend as the aforementioned 500 hPa ridge amplifies and expands farther east across the region with a net result of drier northerly flow aloft and higher mid level geopotential heights. Temperatures will moderate to near normal during this drier period. Another period of convection is possible in about a week from now as a trof moves across the northern prairies. Will continue to tread lightly. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) ISSUED AT 600 AM CDT TUE AUG 13 2013 Afternoon and evening thunderstorms will be possible again today. Cigs could be reduced in heavier thunderstorm activity, but this will be very localized. Light and variable winds will become easterly 10 kt by noon and continuing into this evening. && .PRELIMINARY POINT TEMPS/POPS... DDC 78 59 80 61 / 60 60 30 40 GCK 77 60 78 62 / 50 50 30 40 EHA 83 60 81 62 / 60 60 40 40 LBL 82 61 80 63 / 70 70 30 40 HYS 76 60 78 60 / 40 30 30 40 P28 78 62 81 64 / 70 70 20 40 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...UMSCHEID SHORT TERM...UMSCHEID LONG TERM...Sugden AVIATION...Sugden
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
420 AM CDT Tue Aug 13 2013 ...Update to long term discussion... .SYNOPSIS... ISSUED AT 332 AM CDT TUE AUG 13 2013 During the overnight hours, the heavy rain threat shifted into central and south-central Kansas while much of southwest Kansas was beginning to dry out. The longwave trough continued across eastern Canada into the Great Lakes region...with a reinforcing shortwave trough digging down into the Great Lakes. This shortwave disturbance lead to the frontal passage across Kansas on Monday leading to the evening and late night precipitation event. A mid-upper ridge was found across the northern Rockies, but it was not very substantial ridging and and there were even thunderstorm clusters across eastern Montana within the ridge axis. A 70-80kt 250mb jet also contributed to the organization of last evening`s precipitation event with the upper jet extending from near Las Vegas, NV to central Colorado into eastern Kansas/Nebraska. && .SHORT TERM...(Today and tonight) ISSUED AT 332 AM CDT TUE AUG 13 2013 Main changes in the forecast were lowering the high temperature for today given the likelihood of cloud cover remaining over much of the region. NAM12 and RAP models suggest that clouds will certainly hang in tough for much of the day (especially the RAP model). 700mb temperatures will be cooler today from +6 to +8C with 850mb temps +16 to +18C, so with clouds hanging tough and cooler lower tropospheric temperatures shown by the NAM, RAP, GFS...it is difficult to see afternoon temperatures getting much above the mid to upper 70s. Any sunshine in the afternoon, though, will lead to destabilization and the regeneration of thunderstorms. The strong upper tropospheric jet will remain across Colorado and southern Kansas, so the perturbed mid-upper level flow across the central High Plains will also aid in additional thunderstorm development late in the day. The most likely location for afternoon thunderstorm development will be across eastern Colorado and far western Kansas...farther removed from the influence of last night`s mesoscale convective system (MCS) and the remnant bubble surface high left in its wake. Any new thunderstorms this afternoon may evolve into one or more MCSs, however the best chance at this will be late in the evening and generally west of a Lakin to Liberal line. .LONG TERM...(Wednesday through Monday) ISSUED AT 420 AM CDT TUE AUG 13 2013 Wednesday: A 70 kt 250 hPa jet streak will traverse across western Kansas through the day. At the sfc, an upslope flow regime is expected with weak 850 hPa warm air advection/theta-e advection across far western Kansas. For spatiotemporal adjustments of precipitation probability percentage points, have relied heavily on ECMWF output solutions. Wednesday is shaping up to be another MCS day. Orographic convection is expected to form across the high plains and then drift southeast across the region during the late evening and overnight period. The precipitation numerical values are still in the chance category. The NAM solution is still dry for the most part - but this model has failed with the MCS events recently, so I remain dubious of any described solution herein. The tail end of both WRF cores also support more confidence in the ECMWF solution. Heavy rain will be possible again as precipitable water values are forecast around the 75th percentile for a Gaussian distribution. Otherwise, maximums will be cool because of all the cloud cover and lack of low level downslope flow. Followed the ECE for guidance, which shows values in the upper 70sF to around 80F. Minimums into Thursday morning will be in the lower 60sF. Thursday: Another MCS day is possible Thursday. Upper level flow is more NW during this period as a result the amplification of 500 hPa ridging across the spine of the Rockies. This flow may advect any MCS activity farther east than compared to the previous day. Heavy rain could be a possibility again, as pwats continue on the higher end of the distribution spectrum. Maximum surface temperatures could be a few degrees (F) warmer, particularly across the western zones, as the 850 hPa warm plume advects slightly farther east. A gradient of upper 80sF to around 80F is expected from the west to the east with lows in the 60sF. Friday and beyond: Stuck with the weighted model solution (allblend) for the rest of the forecast period as uncertainty continues to increase. There could be some late afternoon and evening convection across the eastern zones in association with an enhanced region of 850 hPa frontogenesis that the ECMWF solutions shows on Friday. A drier forecast is possible next weekend as the aforementioned 500 hPa ridge amplifies and expands farther east across the region with a net result of drier northerly flow aloft and higher mid level geopotential heights. Temperatures will moderate to near normal during this drier period. Another period of convection is possible in about a week from now as a trof moves across the northern prairies. Will continue to tread lightly. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 100 AM CDT TUE AUG 13 2013 Rain showers and isolated thunderstorms are expected to affect the TAF locations (DDC, GCK, HYS) through 08-09z time frame. Thereafter, a weakening trend in activity is expected. Prevailing winds will be some variation of east through the night and into the day Tuesday. Some temporary MVFR ceilings will be possible in the 10-14z time frame...and perhaps some brief IFR. More showers and thunderstorms are expected by afternoon as the southwest Kansas region remains in a moist upslope low level pattern. && .PRELIMINARY POINT TEMPS/POPS... DDC 78 59 80 61 / 60 60 30 40 GCK 77 60 78 62 / 50 50 30 40 EHA 83 60 81 62 / 60 60 40 40 LBL 82 61 80 63 / 70 70 30 40 HYS 76 60 78 60 / 40 30 30 40 P28 78 62 81 64 / 70 70 20 40 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...UMSCHEID SHORT TERM...UMSCHEID LONG TERM...Sugden AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
334 AM CDT Tue Aug 13 2013 ...UPDATED SYNOPSIS AND SHORT TERM SECTION... .SYNOPSIS... ISSUED AT 332 AM CDT TUE AUG 13 2013 During the overnight hours, the heavy rain threat shifted into central and south-central Kansas while much of southwest Kansas was beginning to dry out. The longwave trough continued across eastern Canada into the Great Lakes region...with a reinforcing shortwave trough digging down into the Great Lakes. This shortwave disturbance lead to the frontal passage across Kansas on Monday leading to the evening and late night precipitation event. A mid-upper ridge was found across the northern Rockies, but it was not very substantial ridging and and there were even thunderstorm clusters across eastern Montana within the ridge axis. A 70-80kt 250mb jet also contributed to the organization of last evening`s precipitation event with the upper jet extending from near Las Vegas, NV to central Colorado into eastern Kansas/Nebraska. && .SHORT TERM...(Today and tonight) ISSUED AT 332 AM CDT TUE AUG 13 2013 Main changes in the forecast were lowering the high temperature for today given the likelihood of cloud cover remaining over much of the region. NAM12 and RAP models suggest that clouds will certainly hang in tough for much of the day (especially the RAP model). 700mb temperatures will be cooler today from +6 to +8C with 850mb temps +16 to +18C, so with clouds hanging tough and cooler lower tropospheric temperatures shown by the NAM, RAP, GFS...it is difficult to see afternoon temperatures getting much above the mid to upper 70s. Any sunshine in the afternoon, though, will lead to destabilization and the regeneration of thunderstorms. The strong upper tropospheric jet will remain across Colorado and southern Kansas, so the perturbed mid-upper level flow across the central High Plains will also aid in additional thunderstorm development late in the day. The most likely location for afternoon thunderstorm development will be across eastern Colorado and far western Kansas...farther removed from the influence of last night`s mesoscale convective system (MCS) and the remnant bubble surface high left in its wake. Any new thunderstorms this afternoon may evolve into one or more MCSs, however the best chance at this will be late in the evening and generally west of a Lakin to Liberal line. .LONG TERM...(Tuesday night through Monday) ISSUED AT 218 PM CDT MON AUG 12 2013 As upper level ridging builds into the Intermountain West, northwesterly upper level flow will prevail across the Plains into Friday. Several ripples in the flow will bring slight chances for showers and thunderstorms into western Kansas, mainly in the late afternoons and evenings, into Friday Night. The upper level ridge will slowly move east and weaken into the weekend with mainly dry conditions and warming temperatures. At the surface, broad high pressure will be found across the Mississippi Valley into the Plains with a trough of low pressure in the lee of the Rockies. Moist south to southeasterly surface flow will prevail. Overnight lows will gradually warm from the low 60s into the mid and upper 60s by the weekend. Daytime highs will warm gradually from the lower to mid 80s to around 85 to 90 by the weekend. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 100 AM CDT TUE AUG 13 2013 Rain showers and isolated thunderstorms are expected to affect the TAF locations (DDC, GCK, HYS) through 08-09z time frame. Thereafter, a weakening trend in activity is expected. Prevailing winds will be some variation of east through the night and into the day Tuesday. Some temporary MVFR ceilings will be possible in the 10-14z time frame...and perhaps some brief IFR. More showers and thunderstorms are expected by afternoon as the southwest Kansas region remains in a moist upslope low level pattern. && .PRELIMINARY POINT TEMPS/POPS... DDC 78 59 80 61 / 60 60 30 40 GCK 77 60 78 62 / 50 50 30 40 EHA 83 60 81 62 / 60 60 40 40 LBL 82 61 80 63 / 70 70 30 40 HYS 76 60 78 60 / 40 30 30 40 P28 78 62 81 64 / 70 70 20 40 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...UMSCHEID SHORT TERM...UMSCHEID LONG TERM...KRUSE AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS JACKSON KY
124 PM EDT TUE AUG 13 2013 .UPDATE... ISSUED AT 124 PM EDT TUE AUG 13 2013 INGESTED THE LATEST OBS DATA TO ESTABLISH NEW TRENDS IN THE HOURLY FORECAST ELEMENTS. ASIDE FROM THAT THE FORECAST WAS ON TRACK WITH NO MAJOR CHANGES REQUIRED. UPDATE ISSUED AT 1127 AM EDT TUE AUG 13 2013 UPDATED THE TODAY PERIOD OF THE FORECAST AND THE HAZARDOUS WEATHER OUTLOOK. UPDATED THE PRECIPITATION PROBABILITIES FOR THE REST OF TODAY TO REFLECT THE LATEST TRENDS IN RADAR IMAGERY AND MOS GUIDANCE. REMOVED MORNING AND AFTERNOON WORDING FROM THE ZONE TEXT PRODUCT AND DECREASED PRECIPITATION CHANCES FOR THE REST OF THE DAY TO THE 30 TO 50 PERCENT CHANCE RANGE. ISOLATED TO SCATTERED SHOWERS AND STORMS ARE EXPECTED TO MOVE ACROSS THE AREA TODAY AS A COLD FRONT MAKES ITS WAY EAST. THIS ACTIVITY...AFTERNOON RAMPING UP A BIT LATE THIS MORNING...IS EXPECTED TO GRADUALLY TAPER OFF DURING THE AFTERNOON AND EARLY EVENING HOURS. ALSO REMOVED MENTION OF FLOODING AND HEAVY RAIN FROM THE HAZARDOUS WEATHER OUTLOOK. IT APPEARS THAT THE THREAT FOR HEAVY RAIN IS FINALLY OVER FOR EASTERN KENTUCKY. UPDATE ISSUED AT 725 AM EDT TUE AUG 13 2013 UPDATED THE NEAR TERM GRIDS TO REFLECT THE BANDED SHOWERS CROSSING THE SOUTHEAST PARTS OF THE CWA. ALSO ADJUSTED THE T/TD GRIDS THROUGH THE NEXT SEVERAL HOURS TO REFLECT THE LATEST OBS AND TRENDS. THE REST OF THE FORECAST REMAINS ON TRACK. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 450 AM EDT TUE AUG 13 2013 08Z SFC ANALYSIS SHOWS A COLD FRONT FINALLY STARTING TO PRESS SOUTH TOWARD THE OHIO RIVER WITH A DRIER AIR MASS BEHIND IT. AHEAD OF THIS...THOUGH...PLENTY OF SHOWERS AND ISOLATED THUNDERSTORMS ARE BRINGING ADDITION BOUTS OF HEAVY RAINS TO EAST KENTUCKY THIS MORNING. EXPECT THE RAINS...AND OCCASIONAL THUNDER...TO CONTINUE INTO THE MORNING HOURS AS THE FRONT GETS CLOSER AND STARTS SHUNTING THE DEEPER MOISTURE...THAT HAS BEEN OVER US FOR MORE THAN A WEEK...SOUTH. PATCHY FOG IS ALSO FOUND OUT THERE WITH DEWPOINTS AND TEMPS NEARLY THE SAME AT EACH OBS SITE...IN THE UPPER 60S AND LOWER 70S. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS THE DEEP TROUGH PIVOTS SOUTH FROM CANADA INTO THE GREAT LAKES TODAY. A TROUGH AXIS FROM THIS WILL SWEEP THROUGH THE OHIO VALLEY ON WEDNESDAY...BUT BY THEN THE LOWER LEVELS WOULD HAVE CLEARED OUT THE DEEPER MOISTURE THROUGHOUT THE AREA. BEFORE THIS HAPPENS...DEEP LAYER SOUTHWEST FLOW LEVELS WILL CONTINUE TO SUPPLY EAST KENTUCKY WITH PLENTY OF MOISTURE THROUGH THE FIRST PART OF THE DAY. GIVEN THE MODEL AGREEMENT HAVE FAVORED THE HIGHER RESOLUTION NAM FOR THIS FORECAST WITH A BLEND TOWARD THE HRRR AND RADAR TRENDS IN THE NEAR TERM. SENSIBLE WEATHER WILL FEATURE ANOTHER 12 HOURS OR SO OF SHOWERS AND THUNDERSTORMS AND ISOLATED HEAVY RAIN BEFORE THE DRIER AND COOLER AIR MOVES INTO EAST KENTUCKY. HAVE CONTINUED TO HIT THIS HARD IN THE HWO...ZONES AND GRIDS. A MUCH MORE COMFORTABLE EVENING CAN BE EXPECTED THROUGH THE AREA...BUT ESPECIALLY NORTHERN PARTS...AS THE LOWER DEWPOINT AIR FILTERS DOWN OUR WAY. AM CONCERNED THAT THE DEEPER VALLEYS TONIGHT MAY NOT MIX DOWN THAT DRY AIR AS EFFECTIVELY AS THE REST OF OUR GEOGRAPHY SETTING THE STAGE FOR FOG...LOCALLY DENSE. ANY FOG WILL QUICKLY MIX OUT BY MID MORNING ON WEDNESDAY WITH A PLEASANT DAY TO FOLLOW. THIS SHOULD ALLOW US ALL TO BREATH SOME RELIEF...DRY OUT...AND TACKLE OUTDOOR PROJECTS THAT THE RAINS OF THE PAST WEEK HAVE DELAYED. AGAIN...USED THE CONSSHORT AS A STARTING POINT FOR WINDS AND DEWPOINTS THROUGH 24 HOURS...THEN CONSALL THEREAFTER. WITH TEMPS... FAVORED THE CONSALL FOR MAX AND MIN VALUES ALONG WITH ITS DERIVED DIURNAL CURVE. DID FINE TUNE THE OVERNIGHT LOWS TONIGHT TO REFLECT A BIT MORE TROUBLE THE COOLER AND DRIER AIR MAY HAVE FILTERING INTO OUR GEOGRAPHIC NOOK AND CRANNIES. AS FOR POPS...HAVE ENDED UP CLOSER TO THE VERY WET MET NUMBERS TODAY AND THEN IN LINE WITH THE DRY GUIDANCE TONIGHT AND WEDNESDAY. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 245 AM EDT TUE AUG 13 2013 AN AMPLIFIED 50H PATTERN WITH A RIDGE OVER THE ROCKIES AND A TROF OVER THE ERN CONUS. AT THE SFC...HIGH PRESSURE OVER THE GREAT LAKES WILL CONTINUE TO PUSH THE COLD FRONT FURTHER TO THE SOUTH WITH DRIER AIR INFILTRATING THE COMMONWEALTH. THIS PATTERN WILL LEAD TO A MOSTLY DRY FCST FOR MUCH OF ERN KY UNTIL THE END OF THE WEEK. BY FRI MORNING AN INVERTED TROF AT THE SFC WILL ALLOW MOISTURE TO CREEP INTO THE AREA AND DAY TIME HEATING COULD SPARK A FEW SHOWERS. THE FCST WILL KEEP THE WEATHER DRY UNTIL LATE FRI EVENING. EVEN AS THIS IS HAPPENING... AT THE 50H LEVEL A VORT MAX IS DROPPING INTO THE CNTRL PLAINS TO REINFORCE THE ERN TROF. THIS VORT MAX WILL DEVELOP OVER THE WEEKEND INTO A CLOSED LOW AS THE SFC HIGH PRESSURE SLIPS TO NEW ENG AND ALLOWS ADDITIONAL MOISTURE TO INVADE THE REGION WITH A GOOD CHANCE OF PRECIP. THE CLOSED LOW WILL BECOME CUT OFF FROM THE PREVAILING WESTERLIES ACROSS THE NRN CONUS BORDER. WITH THE HIGH PRESSURE FILTERING COOLER AIR INTO THE AREA...EXPECT HIGH TEMPS IN THE UPPER 70S FOR THU BEFORE THE RETURNING SOUTHERLY FLOW CAN BOOST HIGHS INTO THE LOWER 80S BY FRI. 80S WILL CONTINUE INTO SAT BEFORE THE EXPECTED PCPN WILL RESTRICT HIGHS BACK TO AROUND 80 FOR SUN AND MON. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 124 PM EDT TUE AUG 13 2013 VARIABLE CONDITIONS ARE EXPECTED AT THE TAF SITES THROUGH THIS EVENING. SCATTERED SHOWERS AND STORMS ARE EXPECTED TO MOVE ACROSS EASTERN KENTUCKY THE REST OF TODAY ALONG A DEPARTING COLD FRONT. CIGS WILL VARY FROM MVFR TO VFR DEPENDING ON THE PROXIMITY OF SHOWERS AND STORMS TO THE TAF SITES. JKL IN PARTICULAR WILL BE CHALLENGING DUE TO ITS RIDGETOP LOCATION. SOME MVFR FOG IS EXPECTED TO FORM ACROSS THE AREA OVERNIGHT...AS SKIES CLEAR OFF AND WINDS DIE DOWN. MOSTLY CLEAR TO PARTLY CLOUDY SKIES ARE EXPECTED ON WEDNESDAY AS HIGH PRESSURE SETTLES OVER THE AREA. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...GREIF LONG TERM...DUSTY AVIATION...AR
AREA FORECAST DISCUSSION
NWS JACKSON KY
1127 AM EDT TUE AUG 13 2013 .UPDATE... ISSUED AT 1127 AM EDT TUE AUG 13 2013 UPDATED THE TODAY PERIOD OF THE FORECAST AND THE HAZARDOUS WEATHER OUTLOOK. UPDATED THE PRECIPITATION PROBABILITIES FOR THE REST OF TODAY TO REFLECT THE LATEST TRENDS IN RADAR IMAGERY AND MOS GUIDANCE. REMOVED MORNING AND AFTERNOON WORDING FROM THE ZONE TEXT PRODUCT AND DECREASED PRECIPITATION CHANCES FOR THE REST OF THE DAY TO THE 30 TO 50 PERCENT CHANCE RANGE. ISOLATED TO SCATTERED SHOWERS AND STORMS ARE EXPECTED TO MOVE ACROSS THE AREA TODAY AS A COLD FRONT MAKES ITS WAY EAST. THIS ACTIVITY...AFTERNOON RAMPING UP A BIT LATE THIS MORNING...IS EXPECTED TO GRADUALLY TAPER OFF DURING THE AFTERNOON AND EARLY EVENING HOURS. ALSO REMOVED MENTION OF FLOODING AND HEAVY RAIN FROM THE HAZARDOUS WEATHER OUTLOOK. IT APPEARS THAT THE THREAT FOR HEAVY RAIN IS FINALLY OVER FOR EASTERN KENTUCKY. UPDATE ISSUED AT 725 AM EDT TUE AUG 13 2013 UPDATED THE NEAR TERM GRIDS TO REFLECT THE BANDED SHOWERS CROSSING THE SOUTHEAST PARTS OF THE CWA. ALSO ADJUSTED THE T/TD GRIDS THROUGH THE NEXT SEVERAL HOURS TO REFLECT THE LATEST OBS AND TRENDS. THE REST OF THE FORECAST REMAINS ON TRACK. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 450 AM EDT TUE AUG 13 2013 08Z SFC ANALYSIS SHOWS A COLD FRONT FINALLY STARTING TO PRESS SOUTH TOWARD THE OHIO RIVER WITH A DRIER AIR MASS BEHIND IT. AHEAD OF THIS...THOUGH...PLENTY OF SHOWERS AND ISOLATED THUNDERSTORMS ARE BRINGING ADDITION BOUTS OF HEAVY RAINS TO EAST KENTUCKY THIS MORNING. EXPECT THE RAINS...AND OCCASIONAL THUNDER...TO CONTINUE INTO THE MORNING HOURS AS THE FRONT GETS CLOSER AND STARTS SHUNTING THE DEEPER MOISTURE...THAT HAS BEEN OVER US FOR MORE THAN A WEEK...SOUTH. PATCHY FOG IS ALSO FOUND OUT THERE WITH DEWPOINTS AND TEMPS NEARLY THE SAME AT EACH OBS SITE...IN THE UPPER 60S AND LOWER 70S. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS THE DEEP TROUGH PIVOTS SOUTH FROM CANADA INTO THE GREAT LAKES TODAY. A TROUGH AXIS FROM THIS WILL SWEEP THROUGH THE OHIO VALLEY ON WEDNESDAY...BUT BY THEN THE LOWER LEVELS WOULD HAVE CLEARED OUT THE DEEPER MOISTURE THROUGHOUT THE AREA. BEFORE THIS HAPPENS...DEEP LAYER SOUTHWEST FLOW LEVELS WILL CONTINUE TO SUPPLY EAST KENTUCKY WITH PLENTY OF MOISTURE THROUGH THE FIRST PART OF THE DAY. GIVEN THE MODEL AGREEMENT HAVE FAVORED THE HIGHER RESOLUTION NAM FOR THIS FORECAST WITH A BLEND TOWARD THE HRRR AND RADAR TRENDS IN THE NEAR TERM. SENSIBLE WEATHER WILL FEATURE ANOTHER 12 HOURS OR SO OF SHOWERS AND THUNDERSTORMS AND ISOLATED HEAVY RAIN BEFORE THE DRIER AND COOLER AIR MOVES INTO EAST KENTUCKY. HAVE CONTINUED TO HIT THIS HARD IN THE HWO...ZONES AND GRIDS. A MUCH MORE COMFORTABLE EVENING CAN BE EXPECTED THROUGH THE AREA...BUT ESPECIALLY NORTHERN PARTS...AS THE LOWER DEWPOINT AIR FILTERS DOWN OUR WAY. AM CONCERNED THAT THE DEEPER VALLEYS TONIGHT MAY NOT MIX DOWN THAT DRY AIR AS EFFECTIVELY AS THE REST OF OUR GEOGRAPHY SETTING THE STAGE FOR FOG...LOCALLY DENSE. ANY FOG WILL QUICKLY MIX OUT BY MID MORNING ON WEDNESDAY WITH A PLEASANT DAY TO FOLLOW. THIS SHOULD ALLOW US ALL TO BREATH SOME RELIEF...DRY OUT...AND TACKLE OUTDOOR PROJECTS THAT THE RAINS OF THE PAST WEEK HAVE DELAYED. AGAIN...USED THE CONSSHORT AS A STARTING POINT FOR WINDS AND DEWPOINTS THROUGH 24 HOURS...THEN CONSALL THEREAFTER. WITH TEMPS... FAVORED THE CONSALL FOR MAX AND MIN VALUES ALONG WITH ITS DERIVED DIURNAL CURVE. DID FINE TUNE THE OVERNIGHT LOWS TONIGHT TO REFLECT A BIT MORE TROUBLE THE COOLER AND DRIER AIR MAY HAVE FILTERING INTO OUR GEOGRAPHIC NOOK AND CRANNIES. AS FOR POPS...HAVE ENDED UP CLOSER TO THE VERY WET MET NUMBERS TODAY AND THEN IN LINE WITH THE DRY GUIDANCE TONIGHT AND WEDNESDAY. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 245 AM EDT TUE AUG 13 2013 AN AMPLIFIED 50H PATTERN WITH A RIDGE OVER THE ROCKIES AND A TROF OVER THE ERN CONUS. AT THE SFC...HIGH PRESSURE OVER THE GREAT LAKES WILL CONTINUE TO PUSH THE COLD FRONT FURTHER TO THE SOUTH WITH DRIER AIR INFILTRATING THE COMMONWEALTH. THIS PATTERN WILL LEAD TO A MOSTLY DRY FCST FOR MUCH OF ERN KY UNTIL THE END OF THE WEEK. BY FRI MORNING AN INVERTED TROF AT THE SFC WILL ALLOW MOISTURE TO CREEP INTO THE AREA AND DAY TIME HEATING COULD SPARK A FEW SHOWERS. THE FCST WILL KEEP THE WEATHER DRY UNTIL LATE FRI EVENING. EVEN AS THIS IS HAPPENING... AT THE 50H LEVEL A VORT MAX IS DROPPING INTO THE CNTRL PLAINS TO REINFORCE THE ERN TROF. THIS VORT MAX WILL DEVELOP OVER THE WEEKEND INTO A CLOSED LOW AS THE SFC HIGH PRESSURE SLIPS TO NEW ENG AND ALLOWS ADDITIONAL MOISTURE TO INVADE THE REGION WITH A GOOD CHANCE OF PRECIP. THE CLOSED LOW WILL BECOME CUT OFF FROM THE PREVAILING WESTERLIES ACROSS THE NRN CONUS BORDER. WITH THE HIGH PRESSURE FILTERING COOLER AIR INTO THE AREA...EXPECT HIGH TEMPS IN THE UPPER 70S FOR THU BEFORE THE RETURNING SOUTHERLY FLOW CAN BOOST HIGHS INTO THE LOWER 80S BY FRI. 80S WILL CONTINUE INTO SAT BEFORE THE EXPECTED PCPN WILL RESTRICT HIGHS BACK TO AROUND 80 FOR SUN AND MON. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 725 AM EDT TUE AUG 13 2013 AVN CONDITIONS THROUGH EAST KENTUCKY WILL REMAIN RATHER POOR DURING THE REST OF MORNING AS AREAS OF CONVECTION AND PATCHY FOG MOVE THROUGH. HAVE LIMITED THE THUNDER AND VCTS CHANCES TO THE SOUTHERN TAF SITES OF LOZ AND SME. ONCE THIS WAVE OF PCPN CLEARS...BY MID MORNING...CONDITIONS WILL IMPROVE THROUGH THE DAY WITH JUST A SMALL CHANCE OF A SHOWER OR THUNDERSTORM AND CIGS GENERALLY HOLDING IN THE VFR RANGE. WILL FORECAST A TOUCH OF FOG DEVELOPING AT LOZ AND SME TAF SITES TOWARD DAWN WEDNESDAY. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE... OUTSIDE OF ANY STORM. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...GREIF LONG TERM...DUSTY AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
725 AM EDT TUE AUG 13 2013 .UPDATE... ISSUED AT 725 AM EDT TUE AUG 13 2013 UPDATED THE NEAR TERM GRIDS TO REFLECT THE BANDED SHOWERS CROSSING THE SOUTHEAST PARTS OF THE CWA. ALSO ADJUSTED THE T/TD GRIDS THROUGH THE NEXT SEVERAL HOURS TO REFLECT THE LATEST OBS AND TRENDS. THE REST OF THE FORECAST REMAINS ON TRACK. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 450 AM EDT TUE AUG 13 2013 08Z SFC ANALYSIS SHOWS A COLD FRONT FINALLY STARTING TO PRESS SOUTH TOWARD THE OHIO RIVER WITH A DRIER AIR MASS BEHIND IT. AHEAD OF THIS...THOUGH...PLENTY OF SHOWERS AND ISOLATED THUNDERSTORMS ARE BRINGING ADDITION BOUTS OF HEAVY RAINS TO EAST KENTUCKY THIS MORNING. EXPECT THE RAINS...AND OCCASIONAL THUNDER...TO CONTINUE INTO THE MORNING HOURS AS THE FRONT GETS CLOSER AND STARTS SHUNTING THE DEEPER MOISTURE...THAT HAS BEEN OVER US FOR MORE THAN A WEEK...SOUTH. PATCHY FOG IS ALSO FOUND OUT THERE WITH DEWPOINTS AND TEMPS NEARLY THE SAME AT EACH OBS SITE...IN THE UPPER 60S AND LOWER 70S. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS THE DEEP TROUGH PIVOTS SOUTH FROM CANADA INTO THE GREAT LAKES TODAY. A TROUGH AXIS FROM THIS WILL SWEEP THROUGH THE OHIO VALLEY ON WEDNESDAY...BUT BY THEN THE LOWER LEVELS WOULD HAVE CLEARED OUT THE DEEPER MOISTURE THROUGHOUT THE AREA. BEFORE THIS HAPPENS...DEEP LAYER SOUTHWEST FLOW LEVELS WILL CONTINUE TO SUPPLY EAST KENTUCKY WITH PLENTY OF MOISTURE THROUGH THE FIRST PART OF THE DAY. GIVEN THE MODEL AGREEMENT HAVE FAVORED THE HIGHER RESOLUTION NAM FOR THIS FORECAST WITH A BLEND TOWARD THE HRRR AND RADAR TRENDS IN THE NEAR TERM. SENSIBLE WEATHER WILL FEATURE ANOTHER 12 HOURS OR SO OF SHOWERS AND THUNDERSTORMS AND ISOLATED HEAVY RAIN BEFORE THE DRIER AND COOLER AIR MOVES INTO EAST KENTUCKY. HAVE CONTINUED TO HIT THIS HARD IN THE HWO...ZONES AND GRIDS. A MUCH MORE COMFORTABLE EVENING CAN BE EXPECTED THROUGH THE AREA...BUT ESPECIALLY NORTHERN PARTS...AS THE LOWER DEWPOINT AIR FILTERS DOWN OUR WAY. AM CONCERNED THAT THE DEEPER VALLEYS TONIGHT MAY NOT MIX DOWN THAT DRY AIR AS EFFECTIVELY AS THE REST OF OUR GEOGRAPHY SETTING THE STAGE FOR FOG...LOCALLY DENSE. ANY FOG WILL QUICKLY MIX OUT BY MID MORNING ON WEDNESDAY WITH A PLEASANT DAY TO FOLLOW. THIS SHOULD ALLOW US ALL TO BREATH SOME RELIEF...DRY OUT...AND TACKLE OUTDOOR PROJECTS THAT THE RAINS OF THE PAST WEEK HAVE DELAYED. AGAIN...USED THE CONSSHORT AS A STARTING POINT FOR WINDS AND DEWPOINTS THROUGH 24 HOURS...THEN CONSALL THEREAFTER. WITH TEMPS... FAVORED THE CONSALL FOR MAX AND MIN VALUES ALONG WITH ITS DERIVED DIURNAL CURVE. DID FINE TUNE THE OVERNIGHT LOWS TONIGHT TO REFLECT A BIT MORE TROUBLE THE COOLER AND DRIER AIR MAY HAVE FILTERING INTO OUR GEOGRAPHIC NOOK AND CRANNIES. AS FOR POPS...HAVE ENDED UP CLOSER TO THE VERY WET MET NUMBERS TODAY AND THEN IN LINE WITH THE DRY GUIDANCE TONIGHT AND WEDNESDAY. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 245 AM EDT TUE AUG 13 2013 AN AMPLIFIED 50H PATTERN WITH A RIDGE OVER THE ROCKIES AND A TROF OVER THE ERN CONUS. AT THE SFC...HIGH PRESSURE OVER THE GREAT LAKES WILL CONTINUE TO PUSH THE COLD FRONT FURTHER TO THE SOUTH WITH DRIER AIR INFILTRATING THE COMMONWEALTH. THIS PATTERN WILL LEAD TO A MOSTLY DRY FCST FOR MUCH OF ERN KY UNTIL THE END OF THE WEEK. BY FRI MORNING AN INVERTED TROF AT THE SFC WILL ALLOW MOISTURE TO CREEP INTO THE AREA AND DAY TIME HEATING COULD SPARK A FEW SHOWERS. THE FCST WILL KEEP THE WEATHER DRY UNTIL LATE FRI EVENING. EVEN AS THIS IS HAPPENING... AT THE 50H LEVEL A VORT MAX IS DROPPING INTO THE CNTRL PLAINS TO REINFORCE THE ERN TROF. THIS VORT MAX WILL DEVELOP OVER THE WEEKEND INTO A CLOSED LOW AS THE SFC HIGH PRESSURE SLIPS TO NEW ENG AND ALLOWS ADDITIONAL MOISTURE TO INVADE THE REGION WITH A GOOD CHANCE OF PRECIP. THE CLOSED LOW WILL BECOME CUT OFF FROM THE PREVAILING WESTERLIES ACROSS THE NRN CONUS BORDER. WITH THE HIGH PRESSURE FILTERING COOLER AIR INTO THE AREA...EXPECT HIGH TEMPS IN THE UPPER 70S FOR THU BEFORE THE RETURNING SOUTHERLY FLOW CAN BOOST HIGHS INTO THE LOWER 80S BY FRI. 80S WILL CONTINUE INTO SAT BEFORE THE EXPECTED PCPN WILL RESTRICT HIGHS BACK TO AROUND 80 FOR SUN AND MON. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 725 AM EDT TUE AUG 13 2013 AVN CONDITIONS THROUGH EAST KENTUCKY WILL REMAIN RATHER POOR DURING THE REST OF MORNING AS AREAS OF CONVECTION AND PATCHY FOG MOVE THROUGH. HAVE LIMITED THE THUNDER AND VCTS CHANCES TO THE SOUTHERN TAF SITES OF LOZ AND SME. ONCE THIS WAVE OF PCPN CLEARS...BY MID MORNING...CONDITIONS WILL IMPROVE THROUGH THE DAY WITH JUST A SMALL CHANCE OF A SHOWER OR THUNDERSTORM AND CIGS GENERALLY HOLDING IN THE VFR RANGE. WILL FORECAST A TOUCH OF FOG DEVELOPING AT LOZ AND SME TAF SITES TOWARD DAWN WEDNESDAY. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE... OUTSIDE OF ANY STORM. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...DUSTY AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
635 AM EDT Tue Aug 13 2013 ...Updated Aviation Discussion... ...Forecast Update... Issued at 600 AM EDT Tue Aug 13 2013 This round of precip seems to be winding down, though these dry periods have been very quick the past few days. Latest RAP indicates some potential for another round somewhere over our western border counties and of course in the still moisture rich environment across the southeast. Brought back some slight chances to the west through the morning then push the dry line south as the front gets through. Speaking of the front, the first one to pass our area is hard to define, except with a weak pressure trough running from near KCVG and then through our northern counties. Second front now is over northern Indiana, with dewpoints the easier find there, readings in the 50s. .SHORT TERM (Now through Wednesday)... Issued at 245 AM EDT Tue Aug 13 2013 A couple of fronts are headed our way today. The first is slower moving and stretches roughly from Lake Erie right to our northern row of counties. The second has a more noticeable dewpoint difference and is located between Central Michigan and southern Wisconsin. Expect the first front to bring a wind shift into the Ohio River area in the next few hours, but the main drier air with the second front will not get here until this afternoon. With a continued moist airmass in place ahead of the first front, we are seeing lines of showers/embedded thunder continue to develop early this morning. Will continue to watch for training of heavier cells, but that watch should end soon, as that second front brings a great rest of the work week forecast. Highs today will depend on who can see the most sunshine. Most places will stay cloudy, keeping readings around 80. The northern forecast area has the best chance to break out behind the front, but north winds should temper the extra sunshine and keep readings in the lower 80s. Tonight, a steady north wind will keep us from ideal radiational cooling, but lows should fall into the 50s for most everyone. Then Wednesday under full sunshine and a north/northeast wind highs look to rise only to the mid/upper 70s. Dewpoints may drop into the mid 40s across the north, very low for mid August! .LONG TERM (Wednesday Night through Monday)... Issued at 300 AM EDT Tue Aug 13 2013 Upper air pattern will undergo a transition during the extended period from troughing centered over the eastern Great Lakes (which has been the prevailing pattern almost all summer) to a more typical mid-summer pattern in which flat zonal flow retreats well north of the Canadian border. However, this latter zonal flow won`t really become established until Monday or Tuesday of next week. A very dry and unseasonably cool airmass will already be in place across the Great Lakes and the Lower Ohio Valley by Wednesday evening. By late Wednesday, high pressure of Canadian origin is forecast to lie near Chicago, with a ridge axis extending southeast toward West Virginia. Clear skies and light winds will allow for almost perfect radiational cooling early Thursday, and some remarkably cool (for mid-August) overnight lows are expected for early Thursday morning. Some lows may dip below 50 across some of our typically colder rural locations! Expect mostly clear skies with very comfortable temperatures and humidities through Friday morning as high pressure settles overhead. Highs both Thursday and Friday will hover not too far from 80. Lows early Friday morning will reach the mid 50s. For Saturday and Sunday, surface high pressure will move over New England, with ridging extending southwest over the Ohio River. Winds will stay quite light through the weekend, mostly from an easterly direction. A weak upper level disturbance will slide south across Missouri late Friday and will establish a weak 500mb trough across southern Illinois, which will basically stay in place through Sunday. Isolated to scattered showers and thunderstorms are expected to our east over the southern Appalachians on Friday, this convection may re-develop a bit farther west Saturday and Sunday as light easterly winds at the surface combine with relatively cool 500mb highs to bring moderate afternoon and evening instability each day. This convection will not be as widespread nor produce the heavy downpours that some locations experienced over this past weekend. They will also tend to develop during the afternoon and diminish during the evening hours. Overall expect partly cloudy skies this weekend with relatively cool highs in the lower to mid 80s with overnight lows in the 60s. Think that each afternoon, scattered thunderstorm coverage will be greatest across our southeastern counties and most sparse across southern Indiana. && .AVIATION (12Z TAF Update)... Issued at 630 AM EDT Tue Aug 13 2013 Cold fronts still north of the terminals this morning. Thus low-level moisture pooled ahead of them will keep lower ceilings in at least for the next few hours. Expect the wind shift to come by mid morning and help start to scour out these ceilings, in concert with daytime heating. We may see a shower/storm at KBWG with the passage around Noon, but then all sites should be VFR with stronger north winds. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........RJS Short Term.....RJS Long Term......JSD Aviation.......RJS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
605 AM EDT Tue Aug 13 2013 ...Forecast Update... Issued at 600 AM EDT Tue Aug 13 2013 This round of precip seems to be winding down, though these dry periods have been very quick the past few days. Latest RAP indicates some potential for another round somewhere over our western border counties and of course in the still moisture rich environment across the southeast. Brought back some slight chances to the west through the morning then push the dry line south as the front gets through. Speaking of the front, the first one to pass our area is hard to define, except with a weak pressure trough running from near KCVG and then through our northern counties. Second front now is over northern Indiana, with dewpoints the easier find there, readings in the 50s. .SHORT TERM (Now through Wednesday)... Issued at 245 AM EDT Tue Aug 13 2013 A couple of fronts are headed our way today. The first is slower moving and stretches roughly from Lake Erie right to our northern row of counties. The second has a more noticeable dewpoint difference and is located between Central Michigan and southern Wisconsin. Expect the first front to bring a wind shift into the Ohio River area in the next few hours, but the main drier air with the second front will not get here until this afternoon. With a continued moist airmass in place ahead of the first front, we are seeing lines of showers/embedded thunder continue to develop early this morning. Will continue to watch for training of heavier cells, but that watch should end soon, as that second front brings a great rest of the work week forecast. Highs today will depend on who can see the most sunshine. Most places will stay cloudy, keeping readings around 80. The northern forecast area has the best chance to break out behind the front, but north winds should temper the extra sunshine and keep readings in the lower 80s. Tonight, a steady north wind will keep us from ideal radiational cooling, but lows should fall into the 50s for most everyone. Then Wednesday under full sunshine and a north/northeast wind highs look to rise only to the mid/upper 70s. Dewpoints may drop into the mid 40s across the north, very low for mid August! .LONG TERM (Wednesday Night through Monday)... Issued at 300 AM EDT Tue Aug 13 2013 Upper air pattern will undergo a transition during the extended period from troughing centered over the eastern Great Lakes (which has been the prevailing pattern almost all summer) to a more typical mid-summer pattern in which flat zonal flow retreats well north of the Canadian border. However, this latter zonal flow won`t really become established until Monday or Tuesday of next week. A very dry and unseasonably cool airmass will already be in place across the Great Lakes and the Lower Ohio Valley by Wednesday evening. By late Wednesday, high pressure of Canadian origin is forecast to lie near Chicago, with a ridge axis extending southeast toward West Virginia. Clear skies and light winds will allow for almost perfect radiational cooling early Thursday, and some remarkably cool (for mid-August) overnight lows are expected for early Thursday morning. Some lows may dip below 50 across some of our typically colder rural locations! Expect mostly clear skies with very comfortable temperatures and humidities through Friday morning as high pressure settles overhead. Highs both Thursday and Friday will hover not too far from 80. Lows early Friday morning will reach the mid 50s. For Saturday and Sunday, surface high pressure will move over New England, with ridging extending southwest over the Ohio River. Winds will stay quite light through the weekend, mostly from an easterly direction. A weak upper level disturbance will slide south across Missouri late Friday and will establish a weak 500mb trough across southern Illinois, which will basically stay in place through Sunday. Isolated to scattered showers and thunderstorms are expected to our east over the southern Appalachians on Friday, this convection may re-develop a bit farther west Saturday and Sunday as light easterly winds at the surface combine with relatively cool 500mb highs to bring moderate afternoon and evening instability each day. This convection will not be as widespread nor produce the heavy downpours that some locations experienced over this past weekend. They will also tend to develop during the afternoon and diminish during the evening hours. Overall expect partly cloudy skies this weekend with relatively cool highs in the lower to mid 80s with overnight lows in the 60s. Think that each afternoon, scattered thunderstorm coverage will be greatest across our southeastern counties and most sparse across southern Indiana. && .AVIATION (06Z TAF Update)... Issued at 1205 AM EDT Tue Aug 13 2013 Did an early round of updates to the TAFs as HRRR is indicating some low cloud development in the wake of last night`s rains. KHNB is coming in with these low clouds and think they will invade points farther east as the night goes on. For now have gone with low-end MVFR cigs, with worse conditions at KLEX by daybreak. Would not be surprised to see some lower ceilings, but will introduce into the TAFs for now and see how trends go the rest of the early morning. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........RJS Short Term.....RJS Long Term......JSD Aviation.......RJS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
450 AM EDT TUE AUG 13 2013 .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 450 AM EDT TUE AUG 13 2013 08Z SFC ANALYSIS SHOWS A COLD FRONT FINALLY STARTING TO PRESS SOUTH TOWARD THE OHIO RIVER WITH A DRIER AIR MASS BEHIND IT. AHEAD OF THIS...THOUGH...PLENTY OF SHOWERS AND ISOLATED THUNDERSTORMS ARE BRINGING ADDITION BOUTS OF HEAVY RAINS TO EAST KENTUCKY THIS MORNING. EXPECT THE RAINS...AND OCCASIONAL THUNDER...TO CONTINUE INTO THE MORNING HOURS AS THE FRONT GETS CLOSER AND STARTS SHUNTING THE DEEPER MOISTURE...THAT HAS BEEN OVER US FOR MORE THAN A WEEK...SOUTH. PATCHY FOG IS ALSO FOUND OUT THERE WITH DEWPOINTS AND TEMPS NEARLY THE SAME AT EACH OBS SITE...IN THE UPPER 60S AND LOWER 70S. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS THE DEEP TROUGH PIVOTS SOUTH FROM CANADA INTO THE GREAT LAKES TODAY. A TROUGH AXIS FROM THIS WILL SWEEP THROUGH THE OHIO VALLEY ON WEDNESDAY...BUT BY THEN THE LOWER LEVELS WOULD HAVE CLEARED OUT THE DEEPER MOISTURE THROUGHOUT THE AREA. BEFORE THIS HAPPENS...DEEP LAYER SOUTHWEST FLOW LEVELS WILL CONTINUE TO SUPPLY EAST KENTUCKY WITH PLENTY OF MOISTURE THROUGH THE FIRST PART OF THE DAY. GIVEN THE MODEL AGREEMENT HAVE FAVORED THE HIGHER RESOLUTION NAM FOR THIS FORECAST WITH A BLEND TOWARD THE HRRR AND RADAR TRENDS IN THE NEAR TERM. SENSIBLE WEATHER WILL FEATURE ANOTHER 12 HOURS OR SO OF SHOWERS AND THUNDERSTORMS AND ISOLATED HEAVY RAIN BEFORE THE DRIER AND COOLER AIR MOVES INTO EAST KENTUCKY. HAVE CONTINUED TO HIT THIS HARD IN THE HWO...ZONES AND GRIDS. A MUCH MORE COMFORTABLE EVENING CAN BE EXPECTED THROUGH THE AREA...BUT ESPECIALLY NORTHERN PARTS...AS THE LOWER DEWPOINT AIR FILTERS DOWN OUR WAY. AM CONCERNED THAT THE DEEPER VALLEYS TONIGHT MAY NOT MIX DOWN THAT DRY AIR AS EFFECTIVELY AS THE REST OF OUR GEOGRAPHY SETTING THE STAGE FOR FOG...LOCALLY DENSE. ANY FOG WILL QUICKLY MIX OUT BY MID MORNING ON WEDNESDAY WITH A PLEASANT DAY TO FOLLOW. THIS SHOULD ALLOW US ALL TO BREATH SOME RELIEF...DRY OUT...AND TACKLE OUTDOOR PROJECTS THAT THE RAINS OF THE PAST WEEK HAVE DELAYED. AGAIN...USED THE CONSSHORT AS A STARTING POINT FOR WINDS AND DEWPOINTS THROUGH 24 HOURS...THEN CONSALL THEREAFTER. WITH TEMPS... FAVORED THE CONSALL FOR MAX AND MIN VALUES ALONG WITH ITS DERIVED DIURNAL CURVE. DID FINE TUNE THE OVERNIGHT LOWS TONIGHT TO REFLECT A BIT MORE TROUBLE THE COOLER AND DRIER AIR MAY HAVE FILTERING INTO OUR GEOGRAPHIC NOOK AND CRANNIES. AS FOR POPS...HAVE ENDED UP CLOSER TO THE VERY WET MET NUMBERS TODAY AND THEN IN LINE WITH THE DRY GUIDANCE TONIGHT AND WEDNESDAY. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 245 AM EDT TUE AUG 13 2013 AN AMPLIFIED 50H PATTERN WITH A RIDGE OVER THE ROCKIES AND A TROF OVER THE ERN CONUS. AT THE SFC...HIGH PRESSURE OVER THE GREAT LAKES WILL CONTINUE TO PUSH THE COLD FRONT FURTHER TO THE SOUTH WITH DRIER AIR INFILTRATING THE COMMONWEALTH. THIS PATTERN WILL LEAD TO A MOSTLY DRY FCST FOR MUCH OF ERN KY UNTIL THE END OF THE WEEK. BY FRI MORNING AN INVERTED TROF AT THE SFC WILL ALLOW MOISTURE TO CREEP INTO THE AREA AND DAY TIME HEATING COULD SPARK A FEW SHOWERS. THE FCST WILL KEEP THE WEATHER DRY UNTIL LATE FRI EVENING. EVEN AS THIS IS HAPPENING... AT THE 50H LEVEL A VORT MAX IS DROPPING INTO THE CNTRL PLAINS TO REINFORCE THE ERN TROF. THIS VORT MAX WILL DEVELOP OVER THE WEEKEND INTO A CLOSED LOW AS THE SFC HIGH PRESSURE SLIPS TO NEW ENG AND ALLOWS ADDITIONAL MOISTURE TO INVADE THE REGION WITH A GOOD CHANCE OF PRECIP. THE CLOSED LOW WILL BECOME CUT OFF FROM THE PREVAILING WESTERLIES ACROSS THE NRN CONUS BORDER. WITH THE HIGH PRESSURE FILTERING COOLER AIR INTO THE AREA...EXPECT HIGH TEMPS IN THE UPPER 70S FOR THU BEFORE THE RETURNING SOUTHERLY FLOW CAN BOOST HIGHS INTO THE LOWER 80S BY FRI. 80S WILL CONTINUE INTO SAT BEFORE THE EXPECTED PCPN WILL RESTRICT HIGHS BACK TO AROUND 80 FOR SUN AND MON. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 245 AM EDT TUE AUG 13 2013 AVN CONDITIONS THROUGH EAST KENTUCKY WILL REMAIN RATHER POOR DURING THE REST OF THE NIGHT AS AREAS OF CONVECTION AND PATCHY FOG MOVE THROUGH. HAVE LIMITED THE THUNDER AND VCTS CHANCES TO THE SOUTHERN TAF SITES OF LOZ AND SME. ONCE THIS WAVE OF PCPN CLEARS LATE THIS NIGHT WOULD ALSO EXPECT LOWER VIS FROM FOG...BUT PROBABLY NOT AS DENSE AS WE SAW LAST NIGHT AT JKL. CONDITIONS WILL THEN IMPROVE THROUGH THE DAY TUESDAY WITH JUST A SMALL CHANCE OF A SHOWER OR THUNDERSTORM AND CIGS GENERALLY HOLDING IN THE VFR RANGE. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...OUTSIDE OF ANY THUNDERSTORM. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...DUSTY AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
304 AM EDT Tue Aug 13 2013 .SHORT TERM (Now through Wednesday)... Issued at 245 AM EDT Tue Aug 13 2013 A couple of fronts are headed our way today. The first is slower moving and stretches roughly from Lake Erie right to our northern row of counties. The second has a more noticeable dewpoint difference and is located between Central Michigan and southern Wisconsin. Expect the first front to bring a wind shift into the Ohio River area in the next few hours, but the main drier air with the second front will not get here until this afternoon. With a continued moist airmass in place ahead of the first front, we are seeing lines of showers/embedded thunder continue to develop early this morning. Will continue to watch for training of heavier cells, but that watch should end soon, as that second front brings a great rest of the work week forecast. Highs today will depend on who can see the most sunshine. Most places will stay cloudy, keeping readings around 80. The northern forecast area has the best chance to break out behind the front, but north winds should temper the extra sunshine and keep readings in the lower 80s. Tonight, a steady north wind will keep us from ideal radiational cooling, but lows should fall into the 50s for most everyone. Then Wednesday under full sunshine and a north/northeast wind highs look to rise only to the mid/upper 70s. Dewpoints may drop into the mid 40s across the north, very low for mid August! .LONG TERM (Wednesday Night through Monday)... Issued at 300 AM EDT Tue Aug 13 2013 Upper air pattern will undergo a transition during the extended period from troughing centered over the eastern Great Lakes (which has been the prevailing pattern almost all summer) to a more typical mid-summer pattern in which flat zonal flow retreats well north of the Canadian border. However, this latter zonal flow won`t really become established until Monday or Tuesday of next week. A very dry and unseasonably cool airmass will already be in place across the Great Lakes and the Lower Ohio Valley by Wednesday evening. By late Wednesday, high pressure of Canadian origin is forecast to lie near Chicago, with a ridge axis extending southeast toward West Virginia. Clear skies and light winds will allow for almost perfect radiational cooling early Thursday, and some remarkably cool (for mid-August) overnight lows are expected for early Thursday morning. Some lows may dip below 50 across some of our typically colder rural locations! Expect mostly clear skies with very comfortable temperatures and humidities through Friday morning as high pressure settles overhead. Highs both Thursday and Friday will hover not too far from 80. Lows early Friday morning will reach the mid 50s. For Saturday and Sunday, surface high pressure will move over New England, with ridging extending southwest over the Ohio River. Winds will stay quite light through the weekend, mostly from an easterly direction. A weak upper level disturbance will slide south across Missouri late Friday and will establish a weak 500mb trough across southern Illinois, which will basically stay in place through Sunday. Isolated to scattered showers and thunderstorms are expected to our east over the southern Appalachians on Friday, this convection may re-develop a bit farther west Saturday and Sunday as light easterly winds at the surface combine with relatively cool 500mb highs to bring moderate afternoon and evening instability each day. This convection will not be as widespread nor produce the heavy downpours that some locations experienced over this past weekend. They will also tend to develop during the afternoon and diminish during the evening hours. Overall expect partly cloudy skies this weekend with relatively cool highs in the lower to mid 80s with overnight lows in the 60s. Think that each afternoon, scattered thunderstorm coverage will be greatest across our southeastern counties and most sparse across southern Indiana. && .AVIATION (06Z TAF Update)... Issued at 1205 AM EDT Tue Aug 13 2013 Did an early round of updates to the TAFs as HRRR is indicating some low cloud development in the wake of last night`s rains. KHNB is coming in with these low clouds and think they will invade points farther east as the night goes on. For now have gone with low-end MVFR cigs, with worse conditions at KLEX by daybreak. Would not be surprised to see some lower ceilings, but will introduce into the TAFs for now and see how trends go the rest of the early morning. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Short Term........RJS Long Term.........JSD Aviation..........RJS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1215 AM CDT Tue Aug 13 2013 .UPDATE... Updated aviation discussion only. && .SHORT TERM...(This Evening through Tuesday Night) ISSUED AT 1250 PM CDT MON AUG 12 2013 It looks like the blended model approach is too slow. It lingers pops well after fropa into/thru Tuesday. We went with the HRRR and Nam`s more meso type solutions, which had higher resolution and initiated well. It has higher pops but departs them more quickly with fropa and with the aforementioned finer resolution. It models the initial environment well, so we at least are hoping for a nice 0-6 hr init with a transition toward the Nam in the overall pop modeling thru Tuesday. Alot will be told here with how the remainder of the pm/into the early evening goes. Should see fairly active/high concentration convection to continue breaking out in moist/unstable air ahead of incoming front/energy this pm- evening...to sweep southward with time/with perhaps additional development along main front as well as outflow boundaries thru the overnight hours. Meso models take the front thru tonight and start to usher in the drier air at the lower levels late tonight- early tmrw, which should preclude pop mention. We`ll watch closely and also see about collab as to whether to remove pop altogether or leave lingering Tuesday pop. Certainly by Tue evening-overnight all models are in agreement that the drier dew points are working thru the column and we poise for the nice pleasant cooler/drier air to take root from mid week on. .LONG TERM /Wednesday through Monday/... ISSUED AT 215 PM CDT MON AUG 12 2013 Unusually high amplitude flow pattern for the middle of August will continue...with a large ridge in the west and a deep trough in the Mississippi and Ohio Valley regions. The trough is forecast to weaken late in the period /Monday/...which will result in some semblance of a typical August pattern. As far as the daily details... An unseasonably strong /1023 mb/ surface high will progress slowly east across the Great Lakes and upper Midwest Wednesday through Thursday. This high will funnel a cool and dry air mass southward...with 850 mb temps ranging from 10 to 12 for much of the period. These 850 mb temps support highs only in the upper 70s with full sun. Overnight lows will be in the lower to mid 50s. Generally followed the cooler NAM mos for low temps...though the difference between NAM and GFS mos is negligible in some places. It should be noted that 850 mb temp anomalies Wed/Thu will be 2 to 3 standard deviations below normal. The air mass will also be very dry. Model soundings suggest nothing more than a few pancake cumulus clouds each afternoon. On Friday and Friday night...an inverted surface trough will retrograde westward across the Tennessee Valley as a 500 mb shortwave digs southeast into the Mississippi Valley. It will take a while for the atmosphere to moisten up...so only the far southeast counties /KHOP area/ nearest the surface trough are at risk of any precip. Saturday through Sunday...the upper trough will be nearly overhead. Some guidance indicates the trough will close off into an upper low over our region. At low levels...the inverted trough will take up residence near or just south of our region. Dew point pooling along the surface trough will bring dew points up through the 60s. Precip water values are forecast to climb steadily to between 1.5 and 2 inches by Sunday /GFS model/. The models are considerably more unstable than they were yesterday...so will add mention of thunder for the weekend. Pops will be in the chance category in most areas for Sunday. Most of the precip should be diurnally driven convection. On Monday...the upper trough is forecast to weaken and/or lift northeast. The surface trough will dissipate...leaving only a weakly cyclonic east to southeast flow. Precip chances will begin to diminish from the west. Temps and humidity will gradually approach climo. && .AVIATION... ISSUED AT 1215 AM CDT TUE AUG 13 2013 Winds across the area will be rather light and generally from the west or sw shortly after midnight, until a cold front passes through the area late in the night, which will turn winds to the nw. There is a small chance of pcpn ahead of the front, but the probability of occurrence was too low to include in TAFs. Winds just off the sfc should be enough to preclude other than brief MVFR fog. Instead, there may be some scattered low clouds associated with the front. VFR conditions can be expected after sunrise, with a nwrly breeze up to about 10 knots. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ Short term...DH Long term...MY Aviation...DB
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1209 AM EDT Tue Aug 13 2013 ...Updated Aviation Discussion... ...Forecast Update... Issued at 1135 PM EDT Mon Aug 12 2013 Main area of precipitation almost is out of the area, though heavy rains continue in the Lake Cumberland region. Once that system exits, we have some signs on radar of a few more bands that could develop overnight, with the main front still to our north. Thus have tweaked pops a little as well as matched up obs with ongoing conditions. Also added in some patchy dense fog as we may get some denser low clouds to drop in spots overnight. KHNB is reporting a 200 foot overcast this hour. Issued at 1000 PM EDT Mon Aug 12 2013 Large cluster of convection continues to work eastward across the state this evening. Torrential rainfall and quite a bit of lightning have been the main weather threats with this activity. Activity will continue to work eastward across the Lake Cumberland region over the next few hours producing torrential rainfall and lightning. Further norther, a break in the precipitation is expected. However, some additional convection may accompany the surface cold front as it continues to press southward through northern Indiana and central Illinois. This will result in a continued threat of a shower or storm into the overnight period, with most locations seeing much drier weather toward dawn Tuesday. Update issued at 602 PM EDT Mon Aug 12 2013 Currently watching two bands of convection work their way across the Commonwealth this evening. The first batch is moving just south of the Louisville metro area. This activity is becoming more outflow dominated while the line surges eastward. Based on current radar trajectories, this activity looks to pass just south of this morning`s heavy rainfall axis which extended from near Spencer Co KY to the Clark/Madison county border region. Additional convection is developing over the northern Bluegrass where the atmosphere has had time to recover this afternoon. Any of these storms will contain a ton of lightning and torrential rainfall. The heavy rainfall and flooding will be the major weather threats with this activity. Second line of convection is organizing out across western Kentucky...along a line from near OWB to just south of PAH. This activity will head east and affect our south-central areas this evening. Quite a bit of lightning and heavy rainfall will be the threats here. However, hydro issues may be a bit more isolated as rainfall has not been that much down there over the last 6-8 hours. Nonetheless, any heavy rainfall will be capable of producing quick rises on creeks, streams, and poor drainage areas. .SHORT TERM (Now through Tuesday Night)... Issued at 315 PM EDT Mon Aug 12 2013 The synoptic pattern this afternoon features zonal flow aloft, which will transition to more of an eastern trough/western ridge pattern through the period. A shortwave trough and associated surface front will slide through the Ohio Valley late this afternoon through the overnight hours, continuing to bring showers and thunderstorms to the region. Quite a complex forecast for the rest of today into tonight, as several forcing mechanisms focus into a moist airmass that has advected into the region. In the near term, a strong wave of isentropic ascent will continue to lift northeast through the northern Bluegrass. After that, there will likely be a brief lull in the more widespread activity. However, with sunshine beginning to peak out, renewed thunderstorm development will likely occur which is already underway across southern Indiana and north-central KY. Think this activity will remain scattered for the next few hours, before the main forcing arrives this evening and increases coverage. A strong shortwave trough, evident on water vapor imagery across central MO, will quickly slide into the Ohio Valley. It is just now beginning to interact with the best instability axis, likely explaining the thunderstorm development recently occurring across southeast MO. This activity will likely expand in coverage through the next few hours as it heads across western IL and KY. However, by the time it reaches the western CWA, it will likely be in a weakening phase as we will not be quite as unstable. Nonetheless, still think coverage will be about 60% as it enters the west, possibly fading in coverage through the late evening into the first part of the overnight hours as instability wanes. Heavy rainfall will continue to be the main threat, although an isolated severe storm will be possible given the better kinematics (effective shear about 40 knots currently in southern IN/northern KY). This may support some multicells or even a transient supercell structure which may be capable of some strong wind gusts or perhaps even some small hail. Overnight, another wave looks as if it will push northeast along the surface front, which may enhance the precipitation across southern KY around midnight as a weak low-level jet develops. This convection will push east by the late morning hours. Some additional development is possible across mainly southern KY through early Tuesday afternoon as another secondary front drops through the region, but think any of this activity will remain rather isolated. Canadian high pressure will build firmly into the region by Tuesday night. After a muggy night tonight, cooler and drier air will push in tomorrow, as highs fall into the low and mid 80s with much lower humidity values. Have dropped temperatures a bit Tuesday night as the Canadian high settles in. Lows will be quite chilly compared to recent days as they bottom out in the mid 50s to lower 60s. .LONG TERM (Wednesday through Monday)... Issued at 315 AM EDT Mon Aug 12 2013 Surface High Pressure dominates the Ohio Valley for the majority of the extended period. By Friday night, as the High starts to exit to the east, southerly low level flow begins to return, and along with it, a returning chance for precipitation - at least for the southern counties along the Tennessee border. The GFS and Euro are in agreement on this trend, but there are differences in the strength of the 500 mb flow, with the GFS generating a closed low and introducing showers as early as Friday evening, while the ECMWF keeps the 500 mb flow an open wave, and brings the convection in on Saturday. Both keep then spread the chance for showers and thunderstorms across the CWA for Sunday and Monday. Given that the main precip chances are in days 6 and 7, and that the southerly surface flow appears more southeasterly in both models, this looks to be a borderline shower/thunderstorm event, and adjustments will no doubt made in intervening forecasts. For now, the most certain statement that can be made is that the best weather of the extended will be during the second half of this work week, with clear skies, dry air and below normal temperatures ushering in the start of the Kentucky State Fair. High temperatures through the period will be in the upper 70s to low 80s. Lows Thursday and Friday mornings will be in the 50s across the area, before moderating into the lower to mid 60s over the weekend and Monday morning. Both the highs and lows are at or below seasonal norms for mid August. && .AVIATION (06Z TAF Update)... Issued at 1205 AM EDT Tue Aug 13 2013 Did an early round of updates to the TAFs as HRRR is indicating some low cloud development in the wake of last night`s rains. KHNB is coming in with these low clouds and think they will invade points farther east as the night goes on. For now have gone with low-end MVFR cigs, with worse conditions at KLEX by daybreak. Would not be surprised to see some lower ceilings, but will introduce into the TAFs for now and see how trends go the rest of the early morning. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Updates........MJ/RJS Short Term.....KJD Long Term......JBS Aviation.......RJS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
410 AM EDT TUE AUG 13 2013 .SYNOPSIS... AFTER A COLD FRONT BRINGS SHOWERS TODAY...COOL AND DRY CONDITIONS CAN BE EXPECTED FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... TWO MAIN AREAS OF RAIN CONTINUE TO PUSH TO THE EAST. NORTHERNMOST TIER OF COUNTIES WILL HAVE SOME STRONG STORMS OVER THE NEXT FEW HOURS...WHILE HEAVY RAIN WILL CONTINUE SOUTH OF THE MASON-DIXON LINE. ALTHOUGH RAIN RATES ACROSS THE SOUTH HAVE DIMINISHED CONSIDERABLY FROM WHAT THEY WERE AT MIDNIGHT...WILL CONTINUE THE FLASH FLOOD WATCH UNTIL THE RAIN CLEARS THE REGION. IN BETWEEN THESE TWO AREAS OF RAIN...ISOLATED SHOWERS/STORMS HAVE STARTED TO DEVELOP. MAJORITY OF RAIN WILL MOVE OFF TO THE EAST BY MID MORNING. HOWEVER...COLD FRONT WILL BRING SIGNIFICANTLY COLDER TEMPERATURES AT 850MB. SFC-850 TEMPERATURE DIFFERENCES WILL BE LARGE ENOUGH FOR SOME LAKE EFFECT CLOUDS AND EVEN ISOLATED SHOWERS TO DEVELOP ALONG THE COLD FRONT. WHILE MESOSCALE MODELS KEEP THE FORECAST DRY...HI-RES MODELS INCLUDING THE HRRR SHOW THESE SHOWERS TO BEGIN BY EARLY AFTERNOON. HAVE KEPT ISOLATED SHOWERS IN THE FORECAST THROUGH MOST OF THE DAY TO ACCOUNT FOR THIS PRECIPITATION. WENT WITH LAMP GUIDANCE FOR TEMPERATURES...WHICH YIELDS HIGHS ABOUT 10 DEGREES BELOW NORMAL. WHILE LAKE EFFECT CLOUD COVER WILL CONTINUE TONIGHT...THINK THAT SHOWERS WILL NOT CONTINUE. BEHIND THE COLD FRONT...LOWS WILL BE 10-15 DEGREES COLDER THAN LAST NIGHT. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... EXPECT QUIET WEATHER THROUGH THIS STRETCH WITH HIGH PRESSURE ACROSS THE GREAT LAKES. HAVE LOWERED TEMPERATURES A COUPLE DEGREES WEDNESDAY AND WEDNESDAY NIGHT. THIS NOW KEEPS LOCATIONS NORTH OF PITTSBURGH IN THE 60S FOR HIGHS...AND DROPS MANY LOCATIONS TO THE 40S WEDNESDAY NIGHT. TEMPERATURES THURS/THURS NIGHT WILL BE ABOUT 5 DEGREES HIGHER THAN THE PREVIOUS DAY. && .LONG TERM /FRIDAY THROUGH MONDAY/... WHILE HIGH PRESSURE WILL REMAIN IN CONTROL OF THE WEATHER FRIDAY AND FRIDAY NIGHT...TROPICAL MOISTURE WILL START TO MOVE IN FROM THE SOUTH. THIS WILL RESULT IN INCREASING CHANCES FOR SHOWERS AND STORMS. MODERATING TEMPERATURES SHOULD BE NEAR NORMAL BY SATURDAY. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... CONDITIONS OVERNIGHT SHOULD DETERIORATE WITH SHOWERS AND LOW CLOUDS MOVING THROUGH. EXPECT MVFR. COULD SEE A BRF PD OF IFR AT PORTS N AND W OF PIT. CLD FNT PASSES 10-14Z. MVFR CIGS SHOULD LINGER THROUGH MOST OF THE MORNING AND INTO EARLY AFTERNOON. IT IS LIKELY THAT EASTERN AND NORTHERN PORTS WILL HOLD ON TO MVFR CLOUDS THE LONGEST. CONDITIONS WILL IMPROVE TO VFR CU/STRATOCU...FROM WEST TO EAST.. DURING THE AFTN. EXP A WSHFT FM SW TO NW AFT FROPA WITH SOME SPEEDS 12G20KT TUE AFTN. .OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... VFR CONDS EXPD THRU THE PD WITH BLDG HIGH PRES. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...FLASH FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR MDZ001. OH...NONE. PA...NONE. WV...FLASH FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR WVZ012- 021>023-041. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
148 PM EDT TUE AUG 13 2013 .SYNOPSIS... ISSUED AT 324 AM EDT TUE AUG 13 2013 HIGH PRESSURE WORKS ITS WAY DOWN INTO THE GREAT LAKES TODAY AND CAMPS OUT FOR SEVERAL DAYS. RAINFALL CHANCES WILL BE ALMOST NIL...WITH A HEALTHY DOSE OF BEAUTIFUL SUMMER WEATHER...THAT WILL WARM INTO THE MIDDLE AND UPPER 70S FOR THE LATTER HALF OF THE WORK WEEK AND UPCOMING WEEKEND. && .UPDATE... ISSUED AT 147 PM EDT TUE AUG 13 2013 EVERYTHING ON TRACK FOR THE MOMENT. EMBEDDED SHORT WAVE TROUGH SEEN IN WATER VAPOR IMAGERY CENTERED JUST NORTHEAST OF SAULT SAINT MARIE...ROTATING SOUTHWARD WITH SOME COLDER CLOUD TOPS SHOWING UP ON ENHANCED IR SATELLITE (INDICATIVE OF SOME SYNOPTIC UPWARD FORCING). SHORT WAVE TROUGH...ALONG WITH ASSOCIATED BETTER MOISTURE WILL BE DROPPING THROUGH THE REGION THROUGH THE COURSE OF THE AFTERNOON. MAY ALREADY BE SEEING THE EFFECTS OF INCREASING FORCING WITH SPOTTY SHOWERS NOW SHOWING UP OVER PARTS OF NRN LOWER MICHIGAN. SO...BEST CHANCES FOR SHOWERS WILL BE OVER THE NEXT SEVERAL HOURS INTO EARLY EVENING...WITH THE COMBINED EFFECTS OF SYNOPTIC FORCING AND LAKE/LAND HEATING INDUCED INSTABILITY. UPDATE ISSUED AT 1034 AM EDT TUE AUG 13 2013 COLD ADVECTION STILL UNDERWAY ACROSS THE GREAT LAKES ON SOMEWHAT GUSTY N/NW WINDS...AHEAD OF HIGH PRESSURE BUILDING INTO THE REGION FROM SOUTH-CENTRAL CANADA. 12Z APX SOUNDING REVEALING AN 850 MB TEMP OF +4C...RATHER COLD FOR THIS TIME OF YEAR AND FORECAST TO BOTTOM OUT AROUND +3C TO +4C THIS AFTERNOON. PLENTY COLD ENOUGH FOR LAKE CONVECTION...AND SURE ENOUGH...LOTS OF TRUE LAKE BANDS HAVE DEVELOPED ON THE LAKES...PARTICULARLY ON LAKES MICHIGAN AND HURON. WITH HEATING...HYBRID LAKE AND LAND HEATING INDUCED STCU WILL OVERSPREAD THE CWA AS WE GO THROUGH THE REST OF THE MORNING...A PROCESS ALREADY UNDERWAY PER SATELLITE TRENDS IN THE LAST HOUR OR SO. DEEP ENOUGH CONVECTION THAT A FEW SHOWERS APPEAR LIKELY THIS AFTERNOON PARTICULARLY DOWNWIND OF THE LAKES WITH THE MOISTURE FEED. IN FACT...APX RADAR ALREADY PICKING UP A FEW RETURNS OFF OF GRAND TRAVERSE BAY. WILL MAKE SOME COSMETIC TWEAKS TO THE GRIDS FOR SCATTERED SHOWERS AND HAVE INCREASED CLOUD COVER THROUGH THE AFTERNOON. OTHERWISE...A DOWNRIGHT COOL DAY AHEAD WITH TEMPS A SOLID 15 DEGREES BELOW NORMAL. UPDATE ISSUED AT 657 AM EDT TUE AUG 13 2013 INCREASED WIND GUSTS IN A FEW SPOTS...MAINLY OVER THE GREAT LAKES...PER LATEST OBS AND INCREASING INSTABILITY. LOW LEVEL MOISTURE EXPECTED TO DEVELOP INTO A PERIOD OF MOSTLY CLOUDY SKIES...OF WHICH DID MAKE A CHANGE TO EXTEND THIS CLOUDIEST TIME PERIOD. OTHERWISE...FORECAST LOOKING GOOD. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 324 AM EDT TUE AUG 13 2013 RATHER ENERGETIC...ALBEIT SOMEWHAT MOISTURE STARVED...PATTERN ESTABLISHED ACROSS THE GREAT LAKES AT THIS EARLY HOUR. YESTERDAY`S SHOWER AND THUNDERSTORM PRODUCING WAVE HAS EXITED WELL TO OUR EAST...WITH ANOTHER WAVE QUICK ON ITS HEELS DIVING SOUTHEAST ACROSS LAKE SUPERIOR. NOT A WHOLE LOT OF SENSIBLE WEATHER GOING ON WITH THIS SECONDARY WAVE...WITH ANY APPRECIABLE MOISTURE STRIPPED OUT BY YESTERDAYS SYSTEM. THAT SAID...THIS WAVE HAS PLENTY OF UNSEASONABLY COLD AIR ASSOCIATED WITH IT...WITH HIGH RES RAP GUIDANCE SHOWING H8 TEMPERATURES IN THE LOWER SINGLE DIGITS OVER EASTERN LAKE SUPERIOR...WITH -20C H5 READINGS MOVING SOUTH ACROSS THE BIG LAKE AS WELL. PLENTY OF COLD ENOUGH AIR TO DRUM UP A LAKE RESPONSE...WITH WELL EVIDENT STCU STREAMERS DEVELOPING OVER NORTHERN LAKE MICHIGAN...HURON...AND FAR EASTERN LAKE SUPERIOR. MOISTURE PROFILES/DEPTH NOT QUITE DEEP ENOUGH TO GENERATE ANY SHOWER ACTIVITY PER RADAR AND OBSERVATION. SUPPOSE A SPRINKLE MAY BE FALLING OUT OF THIS CLOUD DECK...JUST TOO LIGHT TO BE PICKED UP OUR RADAR. WHILE SURFACE CAA NOT QUITE AS IMPRESSIVE AS WHAT IS HAPPENING OVERHEAD...STILL QUITE CHILLY OUT THERE WITH CURRENT READINGS MAINLY IN THE UPPER 40S AND 50S. SHORT TERM FORECAST CONCERNS THROUGH TONIGHT CENTER ON TEMPERATURE/CLOUD TRENDS AS WELL AS SHOWER POTENTIAL AS UPSTREAM WAVE AND ATTENDANT COLD CORE PUSH THROUGH THE REGION. KNOCKING THE EASY PORTION OF THE FORECAST OUT OF THE WAY... TEMPERATURES TODAY AND TONIGHT WILL RUN SEVERAL DEGREES BELOW NORMAL. CULPRIT IS AFOREMENTIONED COLD CORE SYSTEM AND INTENSIFYING LOW LEVEL CAA WITHIN SOMEWHAT GUSTY NORTHWEST SURFACE WINDS. HIGHS TODAY WILL STRUGGLE THROUGH THE MIDDLE AND UPPER 60S...A GOOD 10 DEGREES OR SO BELOW NORMAL (AT LEAST THE WINDS WON`T MAKE IT FEEL ANY COLDER...OH...NEVER MIND). AS FOR RAIN POTENTIAL...MAIN WAVE AND UPWARD QG RESPONSE MOVES THROUGH THIS MORNING...LEAVING OVERHEAD COLD POOL AND POSSIBLE LAKE CONTRIBUTIONS FOR SHOWER GENERATION. NOT A FAN OF SEEING MUCH WITH THE LATTER AS WE HEAD THROUGH THE DAY GIVEN STRONG DIURNAL DISRUPTION AND DRYING LOW LEVELS. LAKES LIKELY WILL ADD AT LEAST SOME BOUNDARY LAYER MOISTURE...PERHAPS HELPING THE OVERHEAD COLD POOL KICK OFF A FEW MOSTLY INTERIOR SHOWERS. H5 TEMPERATURES NEAR -20C DEFINITELY SUPPORTS THIS NOTION. INTERESTINGLY...BOTH NAM-WRF AND GFS BUFFER SOUNDINGS SHOW A RELATIVE WARN NOSE CENTERED AROUND H7...WITH SURFACE BASED PARCELS JUST BARELY SCRAPPING BY THIS LEVEL. REALLY LIKE LOOK OF INHERITED FORECAST FEATURING LOW END SHOWER POTENTIAL...ESPECIALLY ACROSS CLIMATOLOGICALLY FAVORED ARES OF NORTHEAST LOWER AND PARTS OF EASTERN UPPER MICHIGAN. WILL MAKE SOME MINOR CHANGES...BUT GIST OF FORECAST WILL ESSENTIALLY REMAIN UNCHANGED. PLENTY OF DIURNALLY DRIVEN CU/STCU EXPECTED OTHERWISE...LEADING TO A PARTLY TO MOSTLY CLOUDY DAY. YUP...GOING TO FEEL A LOT LIKE THE MIDDLE OF SEPTEMBER! STRONG CANADIAN HIGH PRESSURE CONTINUES TO BUILD INTO THE WESTERN GREAT LAKES TONIGHT...WITH MID LEVEL COLD POOL AND DEEPEST TROUGHING PUSHING OFF TO OUR EAST. THIS SHOULD END ANY LINGERING SHOWER THREAT QUICKLY LATER THIS AFTERNOON...LEADING TO A DRY OVERNIGHT. CLOUD AND TEMPERATURE TRENDS MUCH MORE FORMIDABLE CHALLENGES. GUIDANCE BACKING AWAY FROM ROTATING EASTERN LAKES CLOUD DECK BACK WEST INTO OUR AREA...AND FEEL THE NAM IS MUCH TOO AGGRESSIVE KICKING OFF STRATUS ACROSS THE HIGHLANDS GIVING FLOW PATTERN AND GIVING JUST OFF THE DECK VERY DRY AIR. WILL HEDGE OPTIMISTICALLY (YUP...I SAID IT) AND GO MAINLY CLEAR THROUGH MUCH OF THE OVERNIGHT. UNSEASONABLY COLD AIRMASS ARGUES FOR SOME VERY CHILLY READINGS...ESPECIALLY IF CLEAR SKIES COME TO FRUITION. HOWEVER...NOT ENTIRELY SOLD ON JUST HOW COLD READINGS BECOME TONIGHT...WITH CENTER OF HIGH PRESSURE REMAINING JUST UPSTREAM. WILL NUDGE INHERITED LOWS DOWN A TOUCH...INTRODUCING NEAR 40 DEGREE READINGS IN THE TRADITIONAL ICE BOX LOCATIONS (GRAYLING...ATLANTA...AND SUCH). IF FULL DECOUPLING IS REALIZED...THESE READINGS WILL LIKELY BE A TOUCH TO "WARM"...WITH SOME MID AND UPPER 30S DEFINITELY PLAUSIBLE. EITHER WAY...ANOTHER CHILLY MID AUGUST NIGHT FOR THE NORTH WOODS. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 324 AM EDT TUE AUG 13 2013 A MOISTURE-STARVED NORTHWEST FLOW ALOFT WILL GRADUALLY BECOME MORE ZONAL LATER THIS WEEK AND INTO THE UPCOMING WEEKEND...WITH COOLISH TEMPERATURES WARMING OVER THIS TIME. THERE IS ALMOST NO CHANCE FOR RAINFALL FOR THE NEXT SEVERAL DAYS...AT LEAST ANY CHANCE THAT WOULD BE WORTHY OF BEING INTRODUCED INTO THE FORECAST RIGHT NOW. WEDNESDAY THROUGH FRIDAY...A STOUT NW FLOW ALOFT WILL LOOSEN UP OVER THIS TIME...WITH SLOWLY RISING HEIGHTS...AS RIDGING FROM THE ROCKIES JUST SLOWLY BLEEDS INTO THE HEART OF THE COUNTRY. THERE IS A SERIOUS LACK OF MOISTURE OVER THIS TIME...WITH NO CHANCES FOR RAIN CURRENTLY IN THE FORECAST...OR EVEN CONSIDERED INTO THE FORECAST. THAT SAID...THERE IS A DECENT SHORTWAVE DROPPING IN ACROSS EASTERN ONTARIO/QUEBEC ON THURSDAY...THAT WILL TRY AND LAY OUT A STRIP OF "DEEPER" MOISTURE ALONG SFC TROUGH/COLD FRONT IN EASTERN UPPER. SOMETHING TO KEEP AN EYE ON. TEMPERATURES IN THE MIDDLE AND UPPER 60S WEDNESDAY WILL WARM INTO THE 70S FOR THURSDAY AND FRIDAY. THE MAIN WEATHER STORY MAY BE THE DRYNESS OF THE BL OVER THIS TIME...WITH MODELS MORE THAN LIKELY UNDER-FORECASTING THE MIXING THAT WILL TAKE PLACE. FCST SOUNDINGS SUGGEST +10F DECREASES IN SFC TDS FROM THE MOS NUMBERS. IT`LL BE A DRY LOW LEVEL AIR MASS...BUT WITH WINDS GENERALLY 10KTS OR LESS...FIRE WEATHER CONCERNS ARE MINIMAL. SATURDAY THROUGH MONDAY...SFC HIGH PRESSURE WILL BE OVER THE EAST COAST...BUT TRAILING BACK WESTWARD AND INTO THE GREAT LAKES. THE PATTERN IS VERY SLOW TO MORPH INTO A WEAK ZONAL FLOW. TEMPERATURES WILL CREEP UP INTO THE UPPER 70S AND LOWER 80S OVER THIS TIME...AND AGAIN...WITH VERY MINIMAL CHANCES FOR PRECIPITATION. THERE IS A SUGGESTION THAT A PIECE OF SHORTWAVE ENERGY GETS CUT OFF TO OUR SW...WHICH COULD TECHNICALLY ROAM UP OUR WAY...BUT THE BETTER CHANCE FOR RAIN MAY EVENTUALLY BE WITH A SHORTWAVE AND SFC TROUGH/THETA-E BUMP MORE TOWARD TUESDAY. MAY EVEN STILL BE LOOKING AT CONTINUED LOW AFTERNOON DEW POINTS...MUCH LOWER THAN MODEL NUMBERS. VERY BEAUTIFUL WEATHER IN STORE FOR US. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 147 PM EDT TUE AUG 13 2013 LOTS OF CLOUD COVER DRAPED ACROSS NRN LOWER MICHIGAN THIS AFTERNOON THANKS TO DAYTIME HEATING AND COLD POOL ALOFT DROPPING DOWN THROUGH THE REGION. SPOTTY SHOWERS SHOWING UP ACROSS THE TIP OF THE MITT NEAR KPLN AND ADDITIONAL SHOWER DEVELOPMENT IS ANTICIPATED THIS AFTERNOON AS SHORT WAVE DROPS DOWN THROUGH THE REGION. CIGS WILL REMAIN LARGELY VFR...ALTHOUGH BRIEF BOUTS OF MVFR CIGS ARE POSSIBLE INTO THE EARLY EVENING. GUSTY NORTH WINDS WILL PERSIST WITH HIGHEST GUSTS REACHING THE LOW 20 KNOT RANGE. TONIGHT...WILL THIN OUT QUITE A BIT OF THE CLOUD COVER WITH LOSS OF HEATING...ALTHOUGH TVC/APN MAY RETAIN SCT-BKN CONDITIONS WITH FLOW OFF THE LAKES. GUSTINESS SUBSIDES BUT WE WILL MAINTAIN A SUSTAINED 5 TO 10 KNOT NORTH-NORTHWEST WIND THROUGH THE NIGHT. WINDS TURN MORE NORTHWESTWARD ON WEDNESDAY BUT WITH A BIT LESS GUSTINESS. SCT-BKN VFR CIGS AGAIN ON WEDNESDAY PARTICULARLY AT APN. && .MARINE... ISSUED AT 324 AM EDT TUE AUG 13 2013 MARINE...CONDITIONS MUCH MORE REMINISCENT OF EARLY FALL THAN AUGUST...WITH CANADIAN HIGH PRESSURE BRINGING A BLAST OF UNSEASONABLY CHILLY AIR TO THE BIG WATERS. RATHER TIGHT PRESSURE GRADIENT AND INCREASING OVER-WATER INSTABILITY WILL EASILY ALLOW GOOD DEEP LAYER MIXING OVER THE WATERS...PRODUCING GUSTY NORTHWEST WINDS. LOOKS LIKE TWO CORRIDORS OF STRONGER WIND GUSTS...ONE THROUGH EARLY THIS MORNING...WITH ANOTHER AS WE HEAD THROUGH THIS AFTERNOON AND EARLY EVENING. PLETHORA OF SCA CONDITIONS EXPECTED...A COMBINATION OF GUSTY WINDS AND INCREASINGLY CHOPPY CONDITIONS. WINDS BEGIN TO DIE OFF SOME HEADING INTO LATER TONIGHT AND WEDNESDAY AS THEY SLOWLY BACK MORE WESTERLY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ323-342- 344>346. LS...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LSZ321. && $$ UPDATE...BA SYNOPSIS...SD SHORT TERM...MB LONG TERM...SD AVIATION...BA MARINE...MB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
128 PM EDT TUE AUG 13 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 446 AM EDT TUE AUG 13 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM QUEBEC INTO NRN ONTARIO RESULTING IN CYCLONIC WNW FLOW THROUGH THE NRN GREAT LAKES. LITTLE MORE THAN PATCHY MID CLOUDS WERE ASSOCIATED WITH A SHORTWAVE TROUGH MOVING THROUGH WRN LAKE SUPERIOR WHILE MORE EXTENSIVE CLOUDS AND A FEW SPRINKLES WERE OBSERVED WITH ANOTHER SHRTWV JUST UPSTREAM...TO THE N OF LAKE SUPERIOR. AT THE SFC...HIGH PRES OVER MANITOBA INTO NW MN WAS BUILDING INTO THE WRN LAKES WITH NRLY FLOW PREVAILING ACROSS LAKE SUPERIOR INTO UPPER MICHIGAN. TODAY...AS THE SHRTWV FROM N OF THE LAKE AND A POCKET OF LOWER 700 MB TEMPS AROUND -6C...DROPS THROUGH THE CWA...MODELS SUGGEST THAT SOME ISOLD SHOWERS WILL BE POSSIBLE FROM LATE THIS MORNING INTO THE EARLY AFTERNOON...MAINLY THROUGH W CNTRL UPPER MI. IN ITS WAKE...SUBSIDENCE AND DRYING WILL BUILD QUICKLY INTO THE AREA...ENDING ANY PCPN BY MID TO LATE AFTERNOON. TONIGHT...WITH CLEARING SKIES AND LIGHT WINDS AS THE HIGH BUILD INTO THE REGION...FAVORABLE RADIATIONAL COOLING CONDITIONS IN THE DRY AIRMASS(PWAT TO AROUND 0.50 INCH OR 50 PCT OR NORMAL) WILL ALLOW TEMPERATURES TO DROP TOWARD THE LOWER END OF GUIDANCE....INTO THE MID TO UPPER 30S INLAND WEST. THE TYPICAL COLDER LOCATIONS FROM CHAMPION AND AMASA TO WATERSMEET...KENTON AND WATERSMEET COULD SEE SOME PATCHY FROST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 432 AM EDT TUE AUG 13 2013 THE VERY COOL MORNING TEMPS WILL QUICKLY RISE INTO THE UPPER 60S TO MID 70S WEDNESDAY AS THE SFC HIGH OVERHEAD CONTINUES TO SLOWLY SINK TO OUR SSE. A SLOW WARMING TREND WILL BEGIN WEDNESDAY NIGHT...WITH THE SFC HIGH LINGERING ACROSS THE OHIO VALLEY AND NEW ENGLAND STATES THROUGH AT LEAST THE START OF THE NEXT WORK WEEK. THURSDAY WILL SEE A RETURN OF NEAR NORMAL HIGH TEMPS...IN THE 70S...AS 850MB TEMPS FINALLY RISE INTO THE DOUBLE DIGITS AND...STAY THERE FOR THE REMAINDER OF THE FCST PERIOD. THERE WILL BE ONLY FEW SYSTEMS OF NOTE OVER THE WEEK...WITH NW FLOW ALOFT REMAINING IN PLACE THROUGH THE END OF THE WORK WEEK. THE MAIN 500MB LOW WILL BE SPINNING AROUND AND NEAR QUEBEC THROUGH THURSDAY BEFORE EJECTING NE IN THE MAIN FLOW AROUND THE STRONGER POLAR LOW. A SERIES OF SHORTWAVES WILL ATTEMPT TO ROUND THE HIGH AMPLITUDE RIDGE OVER MUCH OF THE WESTERN STATES EARLY TO MID WEEK... SEEING A SFC LOW TRACKING FROM S ALBERT AND SASKATCHEWAN ON FRIDAY TO S CENTRAL CANADA OVER THE WEEKEND. THE 12/12Z ECMWF IS MUCH QUICKER TO PUSH THE SFC LOW ACROSS HUDSON BAY OVER THE WEEKEND. THERE ARE SIGNIFICANT ENOUGH TIMING DIFFERENCES BETWEEN THE AVAILABLE GUIDANCE TO KEEP ONLY LIGHT CHANCE POPS IN THE FCST AS WARM BUT MAINLY DRY AIR PUSHES IN ON SW WINDS AT THE SFC SATURDAY THROUGH THE END OF THIS FCST PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 127 PM EDT TUE AUG 13 2013 VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD AT ALL TAF SITES...EXCEPT REALLY EARLY THIS AFTERNOON AT SAW. INSTABILITY SC WITH A DISTURBANCE. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 446 AM EDT TUE AUG 13 2013 NRLY WINDS OF 15 TO 20 KNOTS OVER THE ERN PORTIONF OF LAKE SUPERIOR WILL DIMINISH TONIGHT AS HIGH PRES BUILDS INTO THE REGION. AS THE HIGH SINKS TO THE SOUTH WED INTO WED NIGHT WRLY WINDS OF 15 TO 20 KNOTS ARE ALSO EXPECTED OVER CNTRL AND ERN LAKE SUPERIOR. OTHERWISE...WINDS AOB 15 KNOTS WILL PREVAIL INTO SATURDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...KF AVIATION...07 MARINE...JLB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1034 AM EDT TUE AUG 13 2013 .SYNOPSIS... ISSUED AT 324 AM EDT TUE AUG 13 2013 HIGH PRESSURE WORKS ITS WAY DOWN INTO THE GREAT LAKES TODAY AND CAMPS OUT FOR SEVERAL DAYS. RAINFALL CHANCES WILL BE ALMOST NIL...WITH A HEALTHY DOSE OF BEAUTIFUL SUMMER WEATHER...THAT WILL WARM INTO THE MIDDLE AND UPPER 70S FOR THE LATTER HALF OF THE WORK WEEK AND UPCOMING WEEKEND. && .UPDATE... ISSUED AT 1034 AM EDT TUE AUG 13 2013 COLD ADVECTION STILL UNDERWAY ACROSS THE GREAT LAKES ON SOMEWHAT GUSTY N/NW WINDS...AHEAD OF HIGH PRESSURE BUILDING INTO THE REGION FROM SOUTH-CENTRAL CANADA. 12Z APX SOUNDING REVEALING AN 850 MB TEMP OF +4C...RATHER COLD FOR THIS TIME OF YEAR AND FORECAST TO BOTTOM OUT AROUND +3C TO +4C THIS AFTERNOON. PLENTY COLD ENOUGH FOR LAKE CONVECTION...AND SURE ENOUGH...LOTS OF TRUE LAKE BANDS HAVE DEVELOPED ON THE LAKES...PARTICULARLY ON LAKES MICHIGAN AND HURON. WITH HEATING...HYBRID LAKE AND LAND HEATING INDUCED STCU WILL OVERSPREAD THE CWA AS WE GO THROUGH THE REST OF THE MORNING...A PROCESS ALREADY UNDERWAY PER SATELLITE TRENDS IN THE LAST HOUR OR SO. DEEP ENOUGH CONVECTION THAT A FEW SHOWERS APPEAR LIKELY THIS AFTERNOON PARTICULARLY DOWNWIND OF THE LAKES WITH THE MOISTURE FEED. IN FACT...APX RADAR ALREADY PICKING UP A FEW RETURNS OFF OF GRAND TRAVERSE BAY. WILL MAKE SOME COSMETIC TWEAKS TO THE GRIDS FOR SCATTERED SHOWERS AND HAVE INCREASED CLOUD COVER THROUGH THE AFTERNOON. OTHERWISE...A DOWNRIGHT COOL DAY AHEAD WITH TEMPS A SOLID 15 DEGREES BELOW NORMAL. UPDATE ISSUED AT 657 AM EDT TUE AUG 13 2013 INCREASED WIND GUSTS IN A FEW SPOTS...MAINLY OVER THE GREAT LAKES...PER LATEST OBS AND INCREASING INSTABILITY. LOW LEVEL MOISTURE EXPECTED TO DEVELOP INTO A PERIOD OF MOSTLY CLOUDY SKIES...OF WHICH DID MAKE A CHANGE TO EXTEND THIS CLOUDIEST TIME PERIOD. OTHERWISE...FORECAST LOOKING GOOD. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 324 AM EDT TUE AUG 13 2013 RATHER ENERGETIC...ALBEIT SOMEWHAT MOISTURE STARVED...PATTERN ESTABLISHED ACROSS THE GREAT LAKES AT THIS EARLY HOUR. YESTERDAY`S SHOWER AND THUNDERSTORM PRODUCING WAVE HAS EXITED WELL TO OUR EAST...WITH ANOTHER WAVE QUICK ON ITS HEELS DIVING SOUTHEAST ACROSS LAKE SUPERIOR. NOT A WHOLE LOT OF SENSIBLE WEATHER GOING ON WITH THIS SECONDARY WAVE...WITH ANY APPRECIABLE MOISTURE STRIPPED OUT BY YESTERDAYS SYSTEM. THAT SAID...THIS WAVE HAS PLENTY OF UNSEASONABLY COLD AIR ASSOCIATED WITH IT...WITH HIGH RES RAP GUIDANCE SHOWING H8 TEMPERATURES IN THE LOWER SINGLE DIGITS OVER EASTERN LAKE SUPERIOR...WITH -20C H5 READINGS MOVING SOUTH ACROSS THE BIG LAKE AS WELL. PLENTY OF COLD ENOUGH AIR TO DRUM UP A LAKE RESPONSE...WITH WELL EVIDENT STCU STREAMERS DEVELOPING OVER NORTHERN LAKE MICHIGAN...HURON...AND FAR EASTERN LAKE SUPERIOR. MOISTURE PROFILES/DEPTH NOT QUITE DEEP ENOUGH TO GENERATE ANY SHOWER ACTIVITY PER RADAR AND OBSERVATION. SUPPOSE A SPRINKLE MAY BE FALLING OUT OF THIS CLOUD DECK...JUST TOO LIGHT TO BE PICKED UP OUR RADAR. WHILE SURFACE CAA NOT QUITE AS IMPRESSIVE AS WHAT IS HAPPENING OVERHEAD...STILL QUITE CHILLY OUT THERE WITH CURRENT READINGS MAINLY IN THE UPPER 40S AND 50S. SHORT TERM FORECAST CONCERNS THROUGH TONIGHT CENTER ON TEMPERATURE/CLOUD TRENDS AS WELL AS SHOWER POTENTIAL AS UPSTREAM WAVE AND ATTENDANT COLD CORE PUSH THROUGH THE REGION. KNOCKING THE EASY PORTION OF THE FORECAST OUT OF THE WAY... TEMPERATURES TODAY AND TONIGHT WILL RUN SEVERAL DEGREES BELOW NORMAL. CULPRIT IS AFOREMENTIONED COLD CORE SYSTEM AND INTENSIFYING LOW LEVEL CAA WITHIN SOMEWHAT GUSTY NORTHWEST SURFACE WINDS. HIGHS TODAY WILL STRUGGLE THROUGH THE MIDDLE AND UPPER 60S...A GOOD 10 DEGREES OR SO BELOW NORMAL (AT LEAST THE WINDS WON`T MAKE IT FEEL ANY COLDER...OH...NEVER MIND). AS FOR RAIN POTENTIAL...MAIN WAVE AND UPWARD QG RESPONSE MOVES THROUGH THIS MORNING...LEAVING OVERHEAD COLD POOL AND POSSIBLE LAKE CONTRIBUTIONS FOR SHOWER GENERATION. NOT A FAN OF SEEING MUCH WITH THE LATTER AS WE HEAD THROUGH THE DAY GIVEN STRONG DIURNAL DISRUPTION AND DRYING LOW LEVELS. LAKES LIKELY WILL ADD AT LEAST SOME BOUNDARY LAYER MOISTURE...PERHAPS HELPING THE OVERHEAD COLD POOL KICK OFF A FEW MOSTLY INTERIOR SHOWERS. H5 TEMPERATURES NEAR -20C DEFINITELY SUPPORTS THIS NOTION. INTERESTINGLY...BOTH NAM-WRF AND GFS BUFFER SOUNDINGS SHOW A RELATIVE WARN NOSE CENTERED AROUND H7...WITH SURFACE BASED PARCELS JUST BARELY SCRAPPING BY THIS LEVEL. REALLY LIKE LOOK OF INHERITED FORECAST FEATURING LOW END SHOWER POTENTIAL...ESPECIALLY ACROSS CLIMATOLOGICALLY FAVORED ARES OF NORTHEAST LOWER AND PARTS OF EASTERN UPPER MICHIGAN. WILL MAKE SOME MINOR CHANGES...BUT GIST OF FORECAST WILL ESSENTIALLY REMAIN UNCHANGED. PLENTY OF DIURNALLY DRIVEN CU/STCU EXPECTED OTHERWISE...LEADING TO A PARTLY TO MOSTLY CLOUDY DAY. YUP...GOING TO FEEL A LOT LIKE THE MIDDLE OF SEPTEMBER! STRONG CANADIAN HIGH PRESSURE CONTINUES TO BUILD INTO THE WESTERN GREAT LAKES TONIGHT...WITH MID LEVEL COLD POOL AND DEEPEST TROUGHING PUSHING OFF TO OUR EAST. THIS SHOULD END ANY LINGERING SHOWER THREAT QUICKLY LATER THIS AFTERNOON...LEADING TO A DRY OVERNIGHT. CLOUD AND TEMPERATURE TRENDS MUCH MORE FORMIDABLE CHALLENGES. GUIDANCE BACKING AWAY FROM ROTATING EASTERN LAKES CLOUD DECK BACK WEST INTO OUR AREA...AND FEEL THE NAM IS MUCH TOO AGGRESSIVE KICKING OFF STRATUS ACROSS THE HIGHLANDS GIVING FLOW PATTERN AND GIVING JUST OFF THE DECK VERY DRY AIR. WILL HEDGE OPTIMISTICALLY (YUP...I SAID IT) AND GO MAINLY CLEAR THROUGH MUCH OF THE OVERNIGHT. UNSEASONABLY COLD AIRMASS ARGUES FOR SOME VERY CHILLY READINGS...ESPECIALLY IF CLEAR SKIES COME TO FRUITION. HOWEVER...NOT ENTIRELY SOLD ON JUST HOW COLD READINGS BECOME TONIGHT...WITH CENTER OF HIGH PRESSURE REMAINING JUST UPSTREAM. WILL NUDGE INHERITED LOWS DOWN A TOUCH...INTRODUCING NEAR 40 DEGREE READINGS IN THE TRADITIONAL ICE BOX LOCATIONS (GRAYLING...ATLANTA...AND SUCH). IF FULL DECOUPLING IS REALIZED...THESE READINGS WILL LIKELY BE A TOUCH TO "WARM"...WITH SOME MID AND UPPER 30S DEFINITELY PLAUSIBLE. EITHER WAY...ANOTHER CHILLY MID AUGUST NIGHT FOR THE NORTH WOODS. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 324 AM EDT TUE AUG 13 2013 A MOISTURE-STARVED NORTHWEST FLOW ALOFT WILL GRADUALLY BECOME MORE ZONAL LATER THIS WEEK AND INTO THE UPCOMING WEEKEND...WITH COOLISH TEMPERATURES WARMING OVER THIS TIME. THERE IS ALMOST NO CHANCE FOR RAINFALL FOR THE NEXT SEVERAL DAYS...AT LEAST ANY CHANCE THAT WOULD BE WORTHY OF BEING INTRODUCED INTO THE FORECAST RIGHT NOW. WEDNESDAY THROUGH FRIDAY...A STOUT NW FLOW ALOFT WILL LOOSEN UP OVER THIS TIME...WITH SLOWLY RISING HEIGHTS...AS RIDGING FROM THE ROCKIES JUST SLOWLY BLEEDS INTO THE HEART OF THE COUNTRY. THERE IS A SERIOUS LACK OF MOISTURE OVER THIS TIME...WITH NO CHANCES FOR RAIN CURRENTLY IN THE FORECAST...OR EVEN CONSIDERED INTO THE FORECAST. THAT SAID...THERE IS A DECENT SHORTWAVE DROPPING IN ACROSS EASTERN ONTARIO/QUEBEC ON THURSDAY...THAT WILL TRY AND LAY OUT A STRIP OF "DEEPER" MOISTURE ALONG SFC TROUGH/COLD FRONT IN EASTERN UPPER. SOMETHING TO KEEP AN EYE ON. TEMPERATURES IN THE MIDDLE AND UPPER 60S WEDNESDAY WILL WARM INTO THE 70S FOR THURSDAY AND FRIDAY. THE MAIN WEATHER STORY MAY BE THE DRYNESS OF THE BL OVER THIS TIME...WITH MODELS MORE THAN LIKELY UNDER-FORECASTING THE MIXING THAT WILL TAKE PLACE. FCST SOUNDINGS SUGGEST +10F DECREASES IN SFC TDS FROM THE MOS NUMBERS. IT`LL BE A DRY LOW LEVEL AIR MASS...BUT WITH WINDS GENERALLY 10KTS OR LESS...FIRE WEATHER CONCERNS ARE MINIMAL. SATURDAY THROUGH MONDAY...SFC HIGH PRESSURE WILL BE OVER THE EAST COAST...BUT TRAILING BACK WESTWARD AND INTO THE GREAT LAKES. THE PATTERN IS VERY SLOW TO MORPH INTO A WEAK ZONAL FLOW. TEMPERATURES WILL CREEP UP INTO THE UPPER 70S AND LOWER 80S OVER THIS TIME...AND AGAIN...WITH VERY MINIMAL CHANCES FOR PRECIPITATION. THERE IS A SUGGESTION THAT A PIECE OF SHORTWAVE ENERGY GETS CUT OFF TO OUR SW...WHICH COULD TECHNICALLY ROAM UP OUR WAY...BUT THE BETTER CHANCE FOR RAIN MAY EVENTUALLY BE WITH A SHORTWAVE AND SFC TROUGH/THETA-E BUMP MORE TOWARD TUESDAY. MAY EVEN STILL BE LOOKING AT CONTINUED LOW AFTERNOON DEW POINTS...MUCH LOWER THAN MODEL NUMBERS. VERY BEAUTIFUL WEATHER IN STORE FOR US. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 657 AM EDT TUE AUG 13 2013 COLD ADVECTION BEHIND COLD FRONT LAST NIGHT HAS RESULTED IN POCKETS OF MVFR CIGS. THIS SHOULD BE MORE PREVALENT OVER THE NEXT FEW HOURS WITH SUNUP AND FCST SOUNDINGS SHOWING POTENTIAL TRAPPING INVERSION. ONGOING TAFS ARE REALLY HARD TO ARGUE...AS THINGS ARE QUITE TEMPORARY RIGHT NOW ON THE MVFR FRONT. MORE PREVAILING THROUGH EARLY AFTERNOON...WHICH IS WHAT THE TAFS PORTRAY. DRYING THROUGH THE DAY AND LOSS OF SUN WILL LEAD TO PREVAILING VFR CONDITIONS...ALTHOUGH MOISTURE AND INSTABILITY OFF THE LAKE MAY TRY AND KEEP CLOUDS IN LONGER/REDEVELOP...ESPECIALLY OVERNIGHT. GUSTY TODAY ALL AREAS...ESPECIALLY ALONG THE LAKESHORES. GUSTS UP TO 25 KNOTS OUT OF THE NW. && .MARINE... ISSUED AT 324 AM EDT TUE AUG 13 2013 MARINE...CONDITIONS MUCH MORE REMINISCENT OF EARLY FALL THAN AUGUST...WITH CANADIAN HIGH PRESSURE BRINGING A BLAST OF UNSEASONABLY CHILLY AIR TO THE BIG WATERS. RATHER TIGHT PRESSURE GRADIENT AND INCREASING OVER-WATER INSTABILITY WILL EASILY ALLOW GOOD DEEP LAYER MIXING OVER THE WATERS...PRODUCING GUSTY NORTHWEST WINDS. LOOKS LIKE TWO CORRIDORS OF STRONGER WIND GUSTS...ONE THROUGH EARLY THIS MORNING...WITH ANOTHER AS WE HEAD THROUGH THIS AFTERNOON AND EARLY EVENING. PLETHORA OF SCA CONDITIONS EXPECTED...A COMBINATION OF GUSTY WINDS AND INCREASINGLY CHOPPY CONDITIONS. WINDS BEGIN TO DIE OFF SOME HEADING INTO LATER TONIGHT AND WEDNESDAY AS THEY SLOWLY BACK MORE WESTERLY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ323-342- 344>346. LS...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LSZ321. && $$ UPDATE...BA SYNOPSIS...SD SHORT TERM...MB LONG TERM...SD AVIATION...SD MARINE...MB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
737 AM EDT TUE AUG 13 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 446 AM EDT TUE AUG 13 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM QUEBEC INTO NRN ONTARIO RESULTING IN CYCLONIC WNW FLOW THROUGH THE NRN GREAT LAKES. LITTLE MORE THAN PATCHY MID CLOUDS WERE ASSOCIATED WITH A SHORTWAVE TROUGH MOVING THROUGH WRN LAKE SUPERIOR WHILE MORE EXTENSIVE CLOUDS AND A FEW SPRINKLES WERE OBSERVED WITH ANOTHER SHRTWV JUST UPSTREAM...TO THE N OF LAKE SUPERIOR. AT THE SFC...HIGH PRES OVER MANITOBA INTO NW MN WAS BUILDING INTO THE WRN LAKES WITH NRLY FLOW PREVAILING ACROSS LAKE SUPERIOR INTO UPPER MICHIGAN. TODAY...AS THE SHRTWV FROM N OF THE LAKE AND A POCKET OF LOWER 700 MB TEMPS AROUND -6C...DROPS THROUGH THE CWA...MODELS SUGGEST THAT SOME ISOLD SHOWERS WILL BE POSSIBLE FROM LATE THIS MORNING INTO THE EARLY AFTERNOON...MAINLY THROUGH W CNTRL UPPER MI. IN ITS WAKE...SUBSIDENCE AND DRYING WILL BUILD QUICKLY INTO THE AREA...ENDING ANY PCPN BY MID TO LATE AFTERNOON. TONIGHT...WITH CLEARING SKIES AND LIGHT WINDS AS THE HIGH BUILD INTO THE REGION...FAVORABLE RADIATIONAL COOLING CONDITIONS IN THE DRY AIRMASS(PWAT TO AROUND 0.50 INCH OR 50 PCT OR NORMAL) WILL ALLOW TEMPERATURES TO DROP TOWARD THE LOWER END OF GUIDANCE....INTO THE MID TO UPPER 30S INLAND WEST. THE TYPICAL COLDER LOCATIONS FROM CHAMPION AND AMASA TO WATERSMEET...KENTON AND WATERSMEET COULD SEE SOME PATCHY FROST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 432 AM EDT TUE AUG 13 2013 THE VERY COOL MORNING TEMPS WILL QUICKLY RISE INTO THE UPPER 60S TO MID 70S WEDNESDAY AS THE SFC HIGH OVERHEAD CONTINUES TO SLOWLY SINK TO OUR SSE. A SLOW WARMING TREND WILL BEGIN WEDNESDAY NIGHT...WITH THE SFC HIGH LINGERING ACROSS THE OHIO VALLEY AND NEW ENGLAND STATES THROUGH AT LEAST THE START OF THE NEXT WORK WEEK. THURSDAY WILL SEE A RETURN OF NEAR NORMAL HIGH TEMPS...IN THE 70S...AS 850MB TEMPS FINALLY RISE INTO THE DOUBLE DIGITS AND...STAY THERE FOR THE REMAINDER OF THE FCST PERIOD. THERE WILL BE ONLY FEW SYSTEMS OF NOTE OVER THE WEEK...WITH NW FLOW ALOFT REMAINING IN PLACE THROUGH THE END OF THE WORK WEEK. THE MAIN 500MB LOW WILL BE SPINNING AROUND AND NEAR QUEBEC THROUGH THURSDAY BEFORE EJECTING NE IN THE MAIN FLOW AROUND THE STRONGER POLAR LOW. A SERIES OF SHORTWAVES WILL ATTEMPT TO ROUND THE HIGH AMPLITUDE RIDGE OVER MUCH OF THE WESTERN STATES EARLY TO MID WEEK... SEEING A SFC LOW TRACKING FROM S ALBERT AND SASKATCHEWAN ON FRIDAY TO S CENTRAL CANADA OVER THE WEEKEND. THE 12/12Z ECMWF IS MUCH QUICKER TO PUSH THE SFC LOW ACROSS HUDSON BAY OVER THE WEEKEND. THERE ARE SIGNIFICANT ENOUGH TIMING DIFFERENCES BETWEEN THE AVAILABLE GUIDANCE TO KEEP ONLY LIGHT CHANCE POPS IN THE FCST AS WARM BUT MAINLY DRY AIR PUSHES IN ON SW WINDS AT THE SFC SATURDAY THROUGH THE END OF THIS FCST PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 736 AM EDT TUE AUG 13 2013 MORE INSTABILITY CU/SC WILL DEVELOP THIS MORNING WITH THE ONSET OF DAYTIME HEATING AND THE APPROACH OF ANOTHER DISTURBANCE...BUT CONDITIONS ARE LIKELY TO BE VFR. THE BEST CHANCE FOR SOME MVFR CIGS LATER THIS MORNING INTO THE AFTERNOON WILL BE AT SAW WITH MORE FAVORABLE UPSLOPE AND GUSTY N WIND. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 446 AM EDT TUE AUG 13 2013 NRLY WINDS OF 15 TO 20 KNOTS OVER THE ERN PORTIONF OF LAKE SUPERIOR WILL DIMINISH TONIGHT AS HIGH PRES BUILDS INTO THE REGION. AS THE HIGH SINKS TO THE SOUTH WED INTO WED NIGHT WRLY WINDS OF 15 TO 20 KNOTS ARE ALSO EXPECTED OVER CNTRL AND ERN LAKE SUPERIOR. OTHERWISE...WINDS AOB 15 KNOTS WILL PREVAIL INTO SATURDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...KF AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
705 AM EDT TUE AUG 13 2013 .SYNOPSIS... ISSUED AT 324 AM EDT TUE AUG 13 2013 HIGH PRESSURE WORKS ITS WAY DOWN INTO THE GREAT LAKES TODAY AND CAMPS OUT FOR SEVERAL DAYS. RAINFALL CHANCES WILL BE ALMOST NIL...WITH A HEALTHY DOSE OF BEAUTIFUL SUMMER WEATHER...THAT WILL WARM INTO THE MIDDLE AND UPPER 70S FOR THE LATTER HALF OF THE WORK WEEK AND UPCOMING WEEKEND. && .UPDATE... ISSUED AT 657 AM EDT TUE AUG 13 2013 INCREASED WIND GUSTS IN A FEW SPOTS...MAINLY OVER THE GREAT LAKES...PER LATEST OBS AND INCREASING INSTABILITY. LOW LEVEL MOISTURE EXPECTED TO DEVELOP INTO A PERIOD OF MOSTLY CLOUDY SKIES...OF WHICH DID MAKE A CHANGE TO EXTEND THIS CLOUDIEST TIME PERIOD. OTHERWISE...FORECAST LOOKING GOOD. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 324 AM EDT TUE AUG 13 2013 RATHER ENERGETIC...ALBEIT SOMEWHAT MOISTURE STARVED...PATTERN ESTABLISHED ACROSS THE GREAT LAKES AT THIS EARLY HOUR. YESTERDAY`S SHOWER AND THUNDERSTORM PRODUCING WAVE HAS EXITED WELL TO OUR EAST...WITH ANOTHER WAVE QUICK ON ITS HEELS DIVING SOUTHEAST ACROSS LAKE SUPERIOR. NOT A WHOLE LOT OF SENSIBLE WEATHER GOING ON WITH THIS SECONDARY WAVE...WITH ANY APPRECIABLE MOISTURE STRIPPED OUT BY YESTERDAYS SYSTEM. THAT SAID...THIS WAVE HAS PLENTY OF UNSEASONABLY COLD AIR ASSOCIATED WITH IT...WITH HIGH RES RAP GUIDANCE SHOWING H8 TEMPERATURES IN THE LOWER SINGLE DIGITS OVER EASTERN LAKE SUPERIOR...WITH -20C H5 READINGS MOVING SOUTH ACROSS THE BIG LAKE AS WELL. PLENTY OF COLD ENOUGH AIR TO DRUM UP A LAKE RESPONSE...WITH WELL EVIDENT STCU STREAMERS DEVELOPING OVER NORTHERN LAKE MICHIGAN...HURON...AND FAR EASTERN LAKE SUPERIOR. MOISTURE PROFILES/DEPTH NOT QUITE DEEP ENOUGH TO GENERATE ANY SHOWER ACTIVITY PER RADAR AND OBSERVATION. SUPPOSE A SPRINKLE MAY BE FALLING OUT OF THIS CLOUD DECK...JUST TOO LIGHT TO BE PICKED UP OUR RADAR. WHILE SURFACE CAA NOT QUITE AS IMPRESSIVE AS WHAT IS HAPPENING OVERHEAD...STILL QUITE CHILLY OUT THERE WITH CURRENT READINGS MAINLY IN THE UPPER 40S AND 50S. SHORT TERM FORECAST CONCERNS THROUGH TONIGHT CENTER ON TEMPERATURE/CLOUD TRENDS AS WELL AS SHOWER POTENTIAL AS UPSTREAM WAVE AND ATTENDANT COLD CORE PUSH THROUGH THE REGION. KNOCKING THE EASY PORTION OF THE FORECAST OUT OF THE WAY... TEMPERATURES TODAY AND TONIGHT WILL RUN SEVERAL DEGREES BELOW NORMAL. CULPRIT IS AFOREMENTIONED COLD CORE SYSTEM AND INTENSIFYING LOW LEVEL CAA WITHIN SOMEWHAT GUSTY NORTHWEST SURFACE WINDS. HIGHS TODAY WILL STRUGGLE THROUGH THE MIDDLE AND UPPER 60S...A GOOD 10 DEGREES OR SO BELOW NORMAL (AT LEAST THE WINDS WON`T MAKE IT FEEL ANY COLDER...OH...NEVER MIND). AS FOR RAIN POTENTIAL...MAIN WAVE AND UPWARD QG RESPONSE MOVES THROUGH THIS MORNING...LEAVING OVERHEAD COLD POOL AND POSSIBLE LAKE CONTRIBUTIONS FOR SHOWER GENERATION. NOT A FAN OF SEEING MUCH WITH THE LATTER AS WE HEAD THROUGH THE DAY GIVEN STRONG DIURNAL DISRUPTION AND DRYING LOW LEVELS. LAKES LIKELY WILL ADD AT LEAST SOME BOUNDARY LAYER MOISTURE...PERHAPS HELPING THE OVERHEAD COLD POOL KICK OFF A FEW MOSTLY INTERIOR SHOWERS. H5 TEMPERATURES NEAR -20C DEFINITELY SUPPORTS THIS NOTION. INTERESTINGLY...BOTH NAM-WRF AND GFS BUFFER SOUNDINGS SHOW A RELATIVE WARN NOSE CENTERED AROUND H7...WITH SURFACE BASED PARCELS JUST BARELY SCRAPPING BY THIS LEVEL. REALLY LIKE LOOK OF INHERITED FORECAST FEATURING LOW END SHOWER POTENTIAL...ESPECIALLY ACROSS CLIMATOLOGICALLY FAVORED ARES OF NORTHEAST LOWER AND PARTS OF EASTERN UPPER MICHIGAN. WILL MAKE SOME MINOR CHANGES...BUT GIST OF FORECAST WILL ESSENTIALLY REMAIN UNCHANGED. PLENTY OF DIURNALLY DRIVEN CU/STCU EXPECTED OTHERWISE...LEADING TO A PARTLY TO MOSTLY CLOUDY DAY. YUP...GOING TO FEEL A LOT LIKE THE MIDDLE OF SEPTEMBER! STRONG CANADIAN HIGH PRESSURE CONTINUES TO BUILD INTO THE WESTERN GREAT LAKES TONIGHT...WITH MID LEVEL COLD POOL AND DEEPEST TROUGHING PUSHING OFF TO OUR EAST. THIS SHOULD END ANY LINGERING SHOWER THREAT QUICKLY LATER THIS AFTERNOON...LEADING TO A DRY OVERNIGHT. CLOUD AND TEMPERATURE TRENDS MUCH MORE FORMIDABLE CHALLENGES. GUIDANCE BACKING AWAY FROM ROTATING EASTERN LAKES CLOUD DECK BACK WEST INTO OUR AREA...AND FEEL THE NAM IS MUCH TOO AGGRESSIVE KICKING OFF STRATUS ACROSS THE HIGHLANDS GIVING FLOW PATTERN AND GIVING JUST OFF THE DECK VERY DRY AIR. WILL HEDGE OPTIMISTICALLY (YUP...I SAID IT) AND GO MAINLY CLEAR THROUGH MUCH OF THE OVERNIGHT. UNSEASONABLY COLD AIRMASS ARGUES FOR SOME VERY CHILLY READINGS...ESPECIALLY IF CLEAR SKIES COME TO FRUITION. HOWEVER...NOT ENTIRELY SOLD ON JUST HOW COLD READINGS BECOME TONIGHT...WITH CENTER OF HIGH PRESSURE REMAINING JUST UPSTREAM. WILL NUDGE INHERITED LOWS DOWN A TOUCH...INTRODUCING NEAR 40 DEGREE READINGS IN THE TRADITIONAL ICE BOX LOCATIONS (GRAYLING...ATLANTA...AND SUCH). IF FULL DECOUPLING IS REALIZED...THESE READINGS WILL LIKELY BE A TOUCH TO "WARM"...WITH SOME MID AND UPPER 30S DEFINITELY PLAUSIBLE. EITHER WAY...ANOTHER CHILLY MID AUGUST NIGHT FOR THE NORTH WOODS. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 324 AM EDT TUE AUG 13 2013 A MOISTURE-STARVED NORTHWEST FLOW ALOFT WILL GRADUALLY BECOME MORE ZONAL LATER THIS WEEK AND INTO THE UPCOMING WEEKEND...WITH COOLISH TEMPERATURES WARMING OVER THIS TIME. THERE IS ALMOST NO CHANCE FOR RAINFALL FOR THE NEXT SEVERAL DAYS...AT LEAST ANY CHANCE THAT WOULD BE WORTHY OF BEING INTRODUCED INTO THE FORECAST RIGHT NOW. WEDNESDAY THROUGH FRIDAY...A STOUT NW FLOW ALOFT WILL LOOSEN UP OVER THIS TIME...WITH SLOWLY RISING HEIGHTS...AS RIDGING FROM THE ROCKIES JUST SLOWLY BLEEDS INTO THE HEART OF THE COUNTRY. THERE IS A SERIOUS LACK OF MOISTURE OVER THIS TIME...WITH NO CHANCES FOR RAIN CURRENTLY IN THE FORECAST...OR EVEN CONSIDERED INTO THE FORECAST. THAT SAID...THERE IS A DECENT SHORTWAVE DROPPING IN ACROSS EASTERN ONTARIO/QUEBEC ON THURSDAY...THAT WILL TRY AND LAY OUT A STRIP OF "DEEPER" MOISTURE ALONG SFC TROUGH/COLD FRONT IN EASTERN UPPER. SOMETHING TO KEEP AN EYE ON. TEMPERATURES IN THE MIDDLE AND UPPER 60S WEDNESDAY WILL WARM INTO THE 70S FOR THURSDAY AND FRIDAY. THE MAIN WEATHER STORY MAY BE THE DRYNESS OF THE BL OVER THIS TIME...WITH MODELS MORE THAN LIKELY UNDER-FORECASTING THE MIXING THAT WILL TAKE PLACE. FCST SOUNDINGS SUGGEST +10F DECREASES IN SFC TDS FROM THE MOS NUMBERS. IT`LL BE A DRY LOW LEVEL AIR MASS...BUT WITH WINDS GENERALLY 10KTS OR LESS...FIRE WEATHER CONCERNS ARE MINIMAL. SATURDAY THROUGH MONDAY...SFC HIGH PRESSURE WILL BE OVER THE EAST COAST...BUT TRAILING BACK WESTWARD AND INTO THE GREAT LAKES. THE PATTERN IS VERY SLOW TO MORPH INTO A WEAK ZONAL FLOW. TEMPERATURES WILL CREEP UP INTO THE UPPER 70S AND LOWER 80S OVER THIS TIME...AND AGAIN...WITH VERY MINIMAL CHANCES FOR PRECIPITATION. THERE IS A SUGGESTION THAT A PIECE OF SHORTWAVE ENERGY GETS CUT OFF TO OUR SW...WHICH COULD TECHNICALLY ROAM UP OUR WAY...BUT THE BETTER CHANCE FOR RAIN MAY EVENTUALLY BE WITH A SHORTWAVE AND SFC TROUGH/THETA-E BUMP MORE TOWARD TUESDAY. MAY EVEN STILL BE LOOKING AT CONTINUED LOW AFTERNOON DEW POINTS...MUCH LOWER THAN MODEL NUMBERS. VERY BEAUTIFUL WEATHER IN STORE FOR US. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 657 AM EDT TUE AUG 13 2013 COLD ADVECTION BEHIND COLD FRONT LAST NIGHT HAS RESULTED IN POCKETS OF MVFR CIGS. THIS SHOULD BE MORE PREVALENT OVER THE NEXT FEW HOURS WITH SUNUP AND FCST SOUNDINGS SHOWING POTENTIAL TRAPPING INVERSION. ONGOING TAFS ARE REALLY HARD TO ARGUE...AS THINGS ARE QUITE TEMPORARY RIGHT NOW ON THE MVFR FRONT. MORE PREVAILING THROUGH EARLY AFTERNOON...WHICH IS WHAT THE TAFS PORTRAY. DRYING THROUGH THE DAY AND LOSS OF SUN WILL LEAD TO PREVAILING VFR CONDITIONS...ALTHOUGH MOISTURE AND INSTABILITY OFF THE LAKE MAY TRY AND KEEP CLOUDS IN LONGER/REDEVELOP...ESPECIALLY OVERNIGHT. GUSTY TODAY ALL AREAS...ESPECIALLY ALONG THE LAKESHORES. GUSTS UP TO 25 KNOTS OUT OF THE NW. && .MARINE... ISSUED AT 324 AM EDT TUE AUG 13 2013 MARINE...CONDITIONS MUCH MORE REMINISCENT OF EARLY FALL THAN AUGUST...WITH CANADIAN HIGH PRESSURE BRINGING A BLAST OF UNSEASONABLY CHILLY AIR TO THE BIG WATERS. RATHER TIGHT PRESSURE GRADIENT AND INCREASING OVER-WATER INSTABILITY WILL EASILY ALLOW GOOD DEEP LAYER MIXING OVER THE WATERS...PRODUCING GUSTY NORTHWEST WINDS. LOOKS LIKE TWO CORRIDORS OF STRONGER WIND GUSTS...ONE THROUGH EARLY THIS MORNING...WITH ANOTHER AS WE HEAD THROUGH THIS AFTERNOON AND EARLY EVENING. PLETHORA OF SCA CONDITIONS EXPECTED...A COMBINATION OF GUSTY WINDS AND INCREASINGLY CHOPPY CONDITIONS. WINDS BEGIN TO DIE OFF SOME HEADING INTO LATER TONIGHT AND WEDNESDAY AS THEY SLOWLY BACK MORE WESTERLY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ323-342- 344>346. LS...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LSZ321. && $$ UPDATE...SD SYNOPSIS...SD SHORT TERM...MB LONG TERM...SD AVIATION...SD MARINE...MB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
448 AM EDT TUE AUG 13 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 446 AM EDT TUE AUG 13 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM QUEBEC INTO NRN ONTARIO RESULTING IN CYCLONIC WNW FLOW THROUGH THE NRN GREAT LAKES. LITTLE MORE THAN PATCHY MID CLOUDS WERE ASSOCIATED WITH A SHORTWAVE TROUGH MOVING THROUGH WRN LAKE SUPERIOR WHILE MORE EXTENSIVE CLOUDS AND A FEW SPRINKLES WERE OBSERVED WITH ANOTHER SHRTWV JUST UPSTREAM...TO THE N OF LAKE SUPERIOR. AT THE SFC...HIGH PRES OVER MANITOBA INTO NW MN WAS BUILDING INTO THE WRN LAKES WITH NRLY FLOW PREVAILING ACROSS LAKE SUPERIOR INTO UPPER MICHIGAN. TODAY...AS THE SHRTWV FROM N OF THE LAKE AND A POCKET OF LOWER 700 MB TEMPS AROUND -6C...DROPS THROUGH THE CWA...MODELS SUGGEST THAT SOME ISOLD SHOWERS WILL BE POSSIBLE FROM LATE THIS MORNING INTO THE EARLY AFTERNOON...MAINLY THROUGH W CNTRL UPPER MI. IN ITS WAKE...SUBSIDENCE AND DRYING WILL BUILD QUICKLY INTO THE AREA...ENDING ANY PCPN BY MID TO LATE AFTERNOON. TONIGHT...WITH CLEARING SKIES AND LIGHT WINDS AS THE HIGH BUILD INTO THE REGION...FAVORABLE RADIATIONAL COOLING CONDITIONS IN THE DRY AIRMASS(PWAT TO AROUND 0.50 INCH OR 50 PCT OR NORMAL) WILL ALLOW TEMPERATURES TO DROP TOWARD THE LOWER END OF GUIDANCE....INTO THE MID TO UPPER 30S INLAND WEST. THE TYPICAL COLDER LOCATIONS FROM CHAMPION AND AMASA TO WATERSMEET...KENTON AND WATERSMEET COULD SEE SOME PATCHY FROST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 432 AM EDT TUE AUG 13 2013 THE VERY COOL MORNING TEMPS WILL QUICKLY RISE INTO THE UPPER 60S TO MID 70S WEDNESDAY AS THE SFC HIGH OVERHEAD CONTINUES TO SLOWLY SINK TO OUR SSE. A SLOW WARMING TREND WILL BEGIN WEDNESDAY NIGHT...WITH THE SFC HIGH LINGERING ACROSS THE OHIO VALLEY AND NEW ENGLAND STATES THROUGH AT LEAST THE START OF THE NEXT WORK WEEK. THURSDAY WILL SEE A RETURN OF NEAR NORMAL HIGH TEMPS...IN THE 70S...AS 850MB TEMPS FINALLY RISE INTO THE DOUBLE DIGITS AND...STAY THERE FOR THE REMAINDER OF THE FCST PERIOD. THERE WILL BE ONLY FEW SYSTEMS OF NOTE OVER THE WEEK...WITH NW FLOW ALOFT REMAINING IN PLACE THROUGH THE END OF THE WORK WEEK. THE MAIN 500MB LOW WILL BE SPINNING AROUND AND NEAR QUEBEC THROUGH THURSDAY BEFORE EJECTING NE IN THE MAIN FLOW AROUND THE STRONGER POLAR LOW. A SERIES OF SHORTWAVES WILL ATTEMPT TO ROUND THE HIGH AMPLITUDE RIDGE OVER MUCH OF THE WESTERN STATES EARLY TO MID WEEK... SEEING A SFC LOW TRACKING FROM S ALBERT AND SASKATCHEWAN ON FRIDAY TO S CENTRAL CANADA OVER THE WEEKEND. THE 12/12Z ECMWF IS MUCH QUICKER TO PUSH THE SFC LOW ACROSS HUDSON BAY OVER THE WEEKEND. THERE ARE SIGNIFICANT ENOUGH TIMING DIFFERENCES BETWEEN THE AVAILABLE GUIDANCE TO KEEP ONLY LIGHT CHANCE POPS IN THE FCST AS WARM BUT MAINLY DRY AIR PUSHES IN ON SW WINDS AT THE SFC SATURDAY THROUGH THE END OF THIS FCST PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 123 AM EDT TUE AUG 13 2013 EXPECT VFR CONDITIONS AND LGT WINDS TNGT AS DRY HI PRES DOMINATES UPR MI. MORE INSTABILITY CU/SC WL DVLP THIS MRNG AFTER SUNRISE WITH ONSET OF DAYTIME HEATING AND THE APRCH OF ANOTHER DISTURBANCE...BUT CONDITIONS ARE LIKELY TO BE VFR. BEST CHC FOR SOME MVFR CIGS LATER THIS MRNG INTO THE AFTN WL BE AT SAW WITH MORE FVRBL UPSLOPE AND GUSTY N WIND. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 446 AM EDT TUE AUG 13 2013 NRLY WINDS OF 15 TO 20 KNOTS OVER THE ERN PORTIONF OF LAKE SUPERIOR WILL DIMINISH TONIGHT AS HIGH PRES BUILDS INTO THE REGION. AS THE HIGH SINKS TO THE SOUTH WED INTO WED NIGHT WRLY WINDS OF 15 TO 20 KNOTS ARE ALSO EXPECTED OVER CNTRL AND ERN LAKE SUPERIOR. OTHERWISE...WINDS AOB 15 KNOTS WILL PREVAIL INTO SATURDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...KF AVIATION...KC MARINE...JLB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
419 AM EDT TUE AUG 13 2013 .SYNOPSIS... ISSUED AT 324 AM EDT TUE AUG 13 2013 HIGH PRESSURE WORKS ITS WAY DOWN INTO THE GREAT LAKES TODAY AND CAMPS OUT FOR SEVERAL DAYS. RAINFALL CHANCES WILL BE ALMOST NIL...WITH A HEALTHY DOSE OF BEAUTIFUL SUMMER WEATHER...THAT WILL WARM INTO THE MIDDLE AND UPPER 70S FOR THE LATTER HALF OF THE WORK WEEK AND UPCOMING WEEKEND. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 324 AM EDT TUE AUG 13 2013 RATHER ENERGETIC...ALBEIT SOMEWHAT MOISTURE STARVED...PATTERN ESTABLISHED ACROSS THE GREAT LAKES AT THIS EARLY HOUR. YESTERDAY`S SHOWER AND THUNDERSTORM PRODUCING WAVE HAS EXITED WELL TO OUR EAST...WITH ANOTHER WAVE QUICK ON ITS HEELS DIVING SOUTHEAST ACROSS LAKE SUPERIOR. NOT A WHOLE LOT OF SENSIBLE WEATHER GOING ON WITH THIS SECONDARY WAVE...WITH ANY APPRECIABLE MOISTURE STRIPPED OUT BY YESTERDAYS SYSTEM. THAT SAID...THIS WAVE HAS PLENTY OF UNSEASONABLY COLD AIR ASSOCIATED WITH IT...WITH HIGH RES RAP GUIDANCE SHOWING H8 TEMPERATURES IN THE LOWER SINGLE DIGITS OVER EASTERN LAKE SUPERIOR...WITH -20C H5 READINGS MOVING SOUTH ACROSS THE BIG LAKE AS WELL. PLENTY OF COLD ENOUGH AIR TO DRUM UP A LAKE RESPONSE...WITH WELL EVIDENT STCU STREAMERS DEVELOPING OVER NORTHERN LAKE MICHIGAN...HURON...AND FAR EASTERN LAKE SUPERIOR. MOISTURE PROFILES/DEPTH NOT QUITE DEEP ENOUGH TO GENERATE ANY SHOWER ACTIVITY PER RADAR AND OBSERVATION. SUPPOSE A SPRINKLE MAY BE FALLING OUT OF THIS CLOUD DECK...JUST TOO LIGHT TO BE PICKED UP OUR RADAR. WHILE SURFACE CAA NOT QUITE AS IMPRESSIVE AS WHAT IS HAPPENING OVERHEAD...STILL QUITE CHILLY OUT THERE WITH CURRENT READINGS MAINLY IN THE UPPER 40S AND 50S. SHORT TERM FORECAST CONCERNS THROUGH TONIGHT CENTER ON TEMPERATURE/CLOUD TRENDS AS WELL AS SHOWER POTENTIAL AS UPSTREAM WAVE AND ATTENDANT COLD CORE PUSH THROUGH THE REGION. KNOCKING THE EASY PORTION OF THE FORECAST OUT OF THE WAY... TEMPERATURES TODAY AND TONIGHT WILL RUN SEVERAL DEGREES BELOW NORMAL. CULPRIT IS AFOREMENTIONED COLD CORE SYSTEM AND INTENSIFYING LOW LEVEL CAA WITHIN SOMEWHAT GUSTY NORTHWEST SURFACE WINDS. HIGHS TODAY WILL STRUGGLE THROUGH THE MIDDLE AND UPPER 60S...A GOOD 10 DEGREES OR SO BELOW NORMAL (AT LEAST THE WINDS WON`T MAKE IT FEEL ANY COLDER...OH...NEVER MIND). AS FOR RAIN POTENTIAL...MAIN WAVE AND UPWARD QG RESPONSE MOVES THROUGH THIS MORNING...LEAVING OVERHEAD COLD POOL AND POSSIBLE LAKE CONTRIBUTIONS FOR SHOWER GENERATION. NOT A FAN OF SEEING MUCH WITH THE LATTER AS WE HEAD THROUGH THE DAY GIVEN STRONG DIURNAL DISRUPTION AND DRYING LOW LEVELS. LAKES LIKELY WILL ADD AT LEAST SOME BOUNDARY LAYER MOISTURE...PERHAPS HELPING THE OVERHEAD COLD POOL KICK OFF A FEW MOSTLY INTERIOR SHOWERS. H5 TEMPERATURES NEAR -20C DEFINITELY SUPPORTS THIS NOTION. INTERESTINGLY...BOTH NAM-WRF AND GFS BUFFER SOUNDINGS SHOW A RELATIVE WARN NOSE CENTERED AROUND H7...WITH SURFACE BASED PARCELS JUST BARELY SCRAPPING BY THIS LEVEL. REALLY LIKE LOOK OF INHERITED FORECAST FEATURING LOW END SHOWER POTENTIAL...ESPECIALLY ACROSS CLIMATOLOGICALLY FAVORED ARES OF NORTHEAST LOWER AND PARTS OF EASTERN UPPER MICHIGAN. WILL MAKE SOME MINOR CHANGES...BUT GIST OF FORECAST WILL ESSENTIALLY REMAIN UNCHANGED. PLENTY OF DIURNALLY DRIVEN CU/STCU EXPECTED OTHERWISE...LEADING TO A PARTLY TO MOSTLY CLOUDY DAY. YUP...GOING TO FEEL A LOT LIKE THE MIDDLE OF SEPTEMBER! STRONG CANADIAN HIGH PRESSURE CONTINUES TO BUILD INTO THE WESTERN GREAT LAKES TONIGHT...WITH MID LEVEL COLD POOL AND DEEPEST TROUGHING PUSHING OFF TO OUR EAST. THIS SHOULD END ANY LINGERING SHOWER THREAT QUICKLY LATER THIS AFTERNOON...LEADING TO A DRY OVERNIGHT. CLOUD AND TEMPERATURE TRENDS MUCH MORE FORMIDABLE CHALLENGES. GUIDANCE BACKING AWAY FROM ROTATING EASTERN LAKES CLOUD DECK BACK WEST INTO OUR AREA...AND FEEL THE NAM IS MUCH TOO AGGRESSIVE KICKING OFF STRATUS ACROSS THE HIGHLANDS GIVING FLOW PATTERN AND GIVING JUST OFF THE DECK VERY DRY AIR. WILL HEDGE OPTIMISTICALLY (YUP...I SAID IT) AND GO MAINLY CLEAR THROUGH MUCH OF THE OVERNIGHT. UNSEASONABLY COLD AIRMASS ARGUES FOR SOME VERY CHILLY READINGS...ESPECIALLY IF CLEAR SKIES COME TO FRUITION. HOWEVER...NOT ENTIRELY SOLD ON JUST HOW COLD READINGS BECOME TONIGHT...WITH CENTER OF HIGH PRESSURE REMAINING JUST UPSTREAM. WILL NUDGE INHERITED LOWS DOWN A TOUCH...INTRODUCING NEAR 40 DEGREE READINGS IN THE TRADITIONAL ICE BOX LOCATIONS (GRAYLING...ATLANTA...AND SUCH). IF FULL DECOUPLING IS REALIZED...THESE READINGS WILL LIKELY BE A TOUCH TO "WARM"...WITH SOME MID AND UPPER 30S DEFINITELY PLAUSIBLE. EITHER WAY...ANOTHER CHILLY MID AUGUST NIGHT FOR THE NORTH WOODS. && .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 324 AM EDT TUE AUG 13 2013 A MOISTURE-STARVED NORTHWEST FLOW ALOFT WILL GRADUALLY BECOME MORE ZONAL LATER THIS WEEK AND INTO THE UPCOMING WEEKEND...WITH COOLISH TEMPERATURES WARMING OVER THIS TIME. THERE IS ALMOST NO CHANCE FOR RAINFALL FOR THE NEXT SEVERAL DAYS...AT LEAST ANY CHANCE THAT WOULD BE WORTHY OF BEING INTRODUCED INTO THE FORECAST RIGHT NOW. WEDNESDAY THROUGH FRIDAY...A STOUT NW FLOW ALOFT WILL LOOSEN UP OVER THIS TIME...WITH SLOWLY RISING HEIGHTS...AS RIDGING FROM THE ROCKIES JUST SLOWLY BLEEDS INTO THE HEART OF THE COUNTRY. THERE IS A SERIOUS LACK OF MOISTURE OVER THIS TIME...WITH NO CHANCES FOR RAIN CURRENTLY IN THE FORECAST...OR EVEN CONSIDERED INTO THE FORECAST. THAT SAID...THERE IS A DECENT SHORTWAVE DROPPING IN ACROSS EASTERN ONTARIO/QUEBEC ON THURSDAY...THAT WILL TRY AND LAY OUT A STRIP OF "DEEPER" MOISTURE ALONG SFC TROUGH/COLD FRONT IN EASTERN UPPER. SOMETHING TO KEEP AN EYE ON. TEMPERATURES IN THE MIDDLE AND UPPER 60S WEDNESDAY WILL WARM INTO THE 70S FOR THURSDAY AND FRIDAY. THE MAIN WEATHER STORY MAY BE THE DRYNESS OF THE BL OVER THIS TIME...WITH MODELS MORE THAN LIKELY UNDER-FORECASTING THE MIXING THAT WILL TAKE PLACE. FCST SOUNDINGS SUGGEST +10F DECREASES IN SFC TDS FROM THE MOS NUMBERS. IT`LL BE A DRY LOW LEVEL AIR MASS...BUT WITH WINDS GENERALLY 10KTS OR LESS...FIRE WEATHER CONCERNS ARE MINIMAL. SATURDAY THROUGH MONDAY...SFC HIGH PRESSURE WILL BE OVER THE EAST COAST...BUT TRAILING BACK WESTWARD AND INTO THE GREAT LAKES. THE PATTERN IS VERY SLOW TO MORPH INTO A WEAK ZONAL FLOW. TEMPERATURES WILL CREEP UP INTO THE UPPER 70S AND LOWER 80S OVER THIS TIME...AND AGAIN...WITH VERY MINIMAL CHANCES FOR PRECIPITATION. THERE IS A SUGGESTION THAT A PIECE OF SHORTWAVE ENERGY GETS CUT OFF TO OUR SW...WHICH COULD TECHNICALLY ROAM UP OUR WAY...BUT THE BETTER CHANCE FOR RAIN MAY EVENTUALLY BE WITH A SHORTWAVE AND SFC TROUGH/THETA-E BUMP MORE TOWARD TUESDAY. MAY EVEN STILL BE LOOKING AT CONTINUED LOW AFTERNOON DEW POINTS...MUCH LOWER THAN MODEL NUMBERS. VERY BEAUTIFUL WEATHER IN STORE FOR US. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1157 PM EDT MON AUG 12 2013 MVFR CIGS AT TIMES TONIGHT/TUESDAY MORNING. GUSTY NNW WINDS TUESDAY. AUTUMN-LIKE WX IN STORE...AS UNSEASONABLY COOL AIR ENTERS THE REGION BEHIND A DEPARTING COLD FRONT. COOL AIR MOVING OVER THE WARM GREAT LAKES WILL RESULT IN LAKE-INDUCED CLOUD COVER TONIGHT INTO TUESDAY. MVFR CIGS EXPECTED AT ALL TAF SITES...IMPROVING TO VFR DURING THE DAY ON TUESDAY. COULD BE A TOUCH OF DRIZZLE/-RA... ESPECIALLY TVC/APN...BUT SMALL RISK IS NOT WORTH INCLUDING IN THE TAFS AT THIS TIME. NNW-ERLY BREEZE TONIGHT AND TUESDAY...RATHER GUSTY BY MIDDAY TUESDAY. && .MARINE... ISSUED AT 324 AM EDT TUE AUG 13 2013 MARINE...CONDITIONS MUCH MORE REMINISCENT OF EARLY FALL THAN AUGUST...WITH CANADIAN HIGH PRESSURE BRINGING A BLAST OF UNSEASONABLY CHILLY AIR TO THE BIG WATERS. RATHER TIGHT PRESSURE GRADIENT AND INCREASING OVER-WATER INSTABILITY WILL EASILY ALLOW GOOD DEEP LAYER MIXING OVER THE WATERS...PRODUCING GUSTY NORTHWEST WINDS. LOOKS LIKE TWO CORRIDORS OF STRONGER WIND GUSTS...ONE THROUGH EARLY THIS MORNING...WITH ANOTHER AS WE HEAD THROUGH THIS AFTERNOON AND EARLY EVENING. PLETHORA OF SCA CONDITIONS EXPECTED...A COMBINATION OF GUSTY WINDS AND INCREASINGLY CHOPPY CONDITIONS. WINDS BEGIN TO DIE OFF SOME HEADING INTO LATER TONIGHT AND WEDNESDAY AS THEY SLOWLY BACK MORE WESTERLY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ323-342- 344>346. LS...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LSZ321. && $$ SYNOPSIS...SD SHORT TERM...MB LONG TERM...SD AVIATION...JZ MARINE...MB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
640 PM CDT Wed Aug 14 2013 .SHORT TERM...(This Evening through Friday Afternoon) Issued at 257 PM CDT WED AUG 14 2013 The main focus in the short-term remains a series of shortwave troughs sinking southeastward across the Plains this evening, Thursday, and into early Friday. Showers and isolated storms have developed over portions of eastern Nebraska in association with a wave currently pushing southeast toward the forecast area; however, ongoing precipitation will continue to move into fairly dry air this evening, and may struggle against entrainment. Additionally, upper- level flow may push the main area of precipitation more east than south, keeping the bulk of any falling precipitation in central and southern Iowa. Short-term precipitation trends from the HRRR have been fairly consistent today, and also generally limit the south and eastward expansion of showers for this evening and tonight. For now, have kept PoPs very low and confined to far northwest Missouri prior to 06z, then have begun to increase chances in the NW to account for possible regeneration as the low-level jet kicks up early Thursday morning. The next system will follow on the heels of tonight`s as it drops down from eastern Montana on Thursday. Models continue to indicate that the reinforcement of the eastern trough by a second upper low, and the retrograding of a broad upper high, will result in more meridional flow across the Plains for Thursday and Friday. This subtle change will send the second wave a bit west of the forecast area, keeping the better rain chances mainly across portions of central and eastern Kansas. Have left some slight to low-end chance PoPs mainly across the western tier or two of counties on Thursday afternoon and Thursday night, but these could likely be cut further if model trends continue in this direction. Any precipitation that does brush the area will sink southward on Friday morning, leaving behind quiet conditions by Friday afternoon. Temperatures through the period will remain ~10 degrees below normal as cool air continues to filter down the trough and into the eastern Plains and Ohio River valley, with highs generally topping out in the upper 70s to lower 80s, and lows in the 50s to lower 60s under surface high pressure. .LONG TERM...(Friday Evening through Wednesday) Issued at 257 PM CDT WED AUG 14 2013 A quiet medium range forecast for the Central Plains as mid-level ridging currently building over the Rockies begins to move eastward. Despite the increasing heights, Saturday will likely remain below seasonal normals as surface and low-level winds remain light to southeast. By Sunday, we`ll begin to see a steady climb back to or even above normal as winds turn southerly and warmer air begins to advect northward. The first half of next week will again feature quiet conditions as mid-level flow remains weak. Temperatures will have a chance to return to the 90 degree mark by Tuesday and Wednesday, a rare feat this August. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) Issued at 626 PM CDT WED AUG 14 2013 Complex of rain showers moving through eastern Nebraska, southeastward into SE Nebraska and SW Iowa. Dry air in place over most of Western Missouri should hinder the progress of these showers into area, however during the early to mid morning hours Thursday a weak impulse will move through the area, which will aid in shower development across a large portion of western Missouri and eastern Kansas. The scattered nature of the storms along and near Interstate 70, as well as uncertainty as to southern extent of the showery activity has precluded a prevailing rain shower group in the TAFS, however felt as though rain would be in the vicinity of the terminals near I-70. KSTJ will have a better chance of seeing showery activity early Thursday morning, but will nail down that time frame as the showers approach. Aside from the scattered showers, VFR conditions are expected. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Laflin LONG TERM...Dux AVIATION...Leighton
AREA FORECAST DISCUSSION
NWS GLASGOW MT
336 PM MDT TUE AUG 13 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY... WARM AND HUMID CONDITIONS HAVE CONTRIBUTED TO ISOLATED THUNDERSTORMS WITH HEAVY RAIN TODAY. ONE EXAMPLE WAS 2.8" IN SOUTHWEST DANIELS COUNTY. SHOWERS PRESENTLY MOVING SE INTO ROOSEVELT COUNTY BUT ATMOSPHERE IS UNSTABLE TO THE SOUTH WITH CAPE ABOUT 1000 J/KG AND DEWPOINTS IN THE UPPER 50S TO LOW 60S. CERTAINLY RIPE CONDITIONS FOR HEAVY RAIN. RUC AND HRRR CONTINUE TO SHOW THIS INTO THE EVENING HOURS MAINLY IN THE EASTERN ZONES. THREAT SHOULD END THEREAFTER. ON WEDNESDAY...DIURNAL HEATING WILL SPARK SHOWERS AND THUNDERSTORMS AGAIN AS UPPER LEVELS REMAIN UNSETTLED WITH LOW LEVEL WARMTH AND HUMIDITY. NOT CONFIDENT ENOUGH TO PIN-POINT WHERE HEAVY RAINS WILL OCCUR AND DIDN/T FEEL COMFORTABLE TO BROADBRUSH THIS. SMALL HAIL AND GUSTY WINDS ARE ALSO POSSIBLE BUT AGAIN DID NOT WANT TO BROADBRUSH...AND IT/S ALREADY MENTIONED IN THE HWO. BY THURSDAY...THE UPPER RIDGE BUILDS IN AND SUPPRESSES CONVECTION. WITH MORE SUNSHINE...TEMPERATURES WILL BE WARMER. AIRMASS WILL BE MORE HUMID OVER THE EASTERN ZONES BUT ANY THUNDERSTORM DEVELOPMENT WILL BE OVER THE DAKOTAS. TFJ .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... A GOOD CHUNK OF THE PREVIOUS FORECAST STILL STANDS... BUT A COUPLE PLACES NEEDED TWEAKING. FIRST... OVERNIGHT LOWS POST FRIDAY RIDGE NEEDED TO BE DRUG DOWN AS THEY WARMED FAR TOO FAST FOR SOUTHWEST FOLLOWED BY ZONAL FLOW ALOFT THROUGH EARLY NEXT WEEK. ALSO... ACTED TO STRIP OUT ZERO POPS FOR THE SAME TIME PERIOD AS VARIABILITY BEGINS TO CREEP INTO THE FORECAST POST SUNDAY AMONG OPERATIONAL EC VERSUS ITS ENSEMBLE MEMBERS... WHILE NO REAL ANALOGS FROM THE PAST 60 DAYS ARE YET AVAILABLE FOR THESE PERIODS. GAH PREVIOUS LONG TERM DISCUSSION... THE LONG TERM FORECAST PERIOD BEGINS WITH A STRONG UPPER LEVEL RIDGE IN PLACE WITH ITS AXIS DIRECTLY THROUGH NORTHEAST MONTANA. EXCELLENT MODEL AGREEMENT IN KEEPING THE ENTIRE CWA CONSEQUENTLY DRY. THIS WILL ALLOW THE HOTTEST TEMPERATURES OF THE SUMMER SEASON TO FINALLY ARRIVE...TOPPING OUT IN THE LOW TO MID 90S...ALTHOUGH SOME NUMERICAL GUIDANCE SUGGESTS THAT EVEN THIS MAY BE TOO CONSERVATIVE FOR FRIDAY AND SATURDAY HIGH TEMPERATURES. FOR NOW FELT IT WAS BEST TO SHOW A GRADUAL INCREASE UNTIL MORE MODEL CONSENSUS IS EVIDENT. WITH A COOL FRONT SET TO MOVE THROUGH THE AREA ON SATURDAY NIGHT...SCATTERED SHOWERS AND THUNDERSTORMS WILL BE ON THE HEELS OF SOME MUCH AWAITED NORTHWESTERLY SURFACE WINDS UNDER SOUTHWESTERLY FLOW ALOFT COURTESY OF THE UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST COASTAL AREA. THIS UNSETTLED PERIOD SHOULD REMAIN OVER THE REGION WHILE A SHORT WAVE TROUGH PUSHES THROUGH THE AREA THROUGH MONDAY MORNING...WITH THE BEST CHANCES FOR PRECIP FOCUSED FROM SATURDAY NIGHT THROUGH SUNDAY MORNING. MONDAY AND BEYOND...STRONG SUMMER RIDGING FROM THE SOUTHWEST MOVES IN AGAIN TO CUT OFF THE PRECIPITATION WITH TEMPERATURES WARMING BACK UP INTO THE 90S. && .AVIATION... FLIGHT CATEGORY: MAINLY VFR. MVFR POSSIBLE WITH EVENING THUNDER OR OVERNIGHT FOG. THUNDER: SCATTERED SHOWERS AND THUNDERSTORMS ARE IN SWING THIS AFTERNOON NEAR THE KOLF... KSDY... AND KGDV TERMINALS AND MAY CONTINUE THROUGH THE EARLY EVENING. AMENDMENTS MAY BE NEEDED. AS USUAL... BRIEF VISIBILITY OBSCURATION AND SUDDEN GUSTY WINDS ARE POSSIBLE NEAR ANY THUNDERSTORM. FOG: WHILE CHANCES ARE NOT HIGH ENOUGH TO DIRECTLY INCLUDE IN THE TAFS... A SMALL CHANCE FOR FOG DOES EXIST AT KOLF OR KSDY TONIGHT. FOG IS MOST POSSIBLE NEAR THE EXCESS OF MOISTURE FROM SHOWERS EARLIER IN THE EVENING. BEST WINDOW FOR FOG WOULD BE BETWEEN 08Z AS WINDS DROPS OFF THROUGH 13Z RIGHT AFTER SUN UP. AREA WINDS: WINDS WILL BE OUT OF THE SOUTH AND EAST AROUND 10 KTS SUSTAINED... GUSTING UP TO 15 KTS DURING THE AFTERNOON. GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GLASGOW MT
229 PM MDT TUE AUG 13 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY... WARM AND HUMID CONDITIONS HAVE CONTRIBUTED TO ISOLATED THUNDERSTORMS WITH HEAVY RAIN TODAY. ONE EXAMPLE WAS 2.8" IN SOUTHWEST DANIELS COUNTY. SHOWERS PRESENTLY MOVING SE INTO ROOSEVELT COUNTY BUT ATMOSPHERE IS UNSTABLE TO THE SOUTH WITH CAPE ABOUT 1000 J/KG AND DEWPOINTS IN THE UPPER 50S TO LOW 60S. CERTAINLY RIPE CONDITIONS FOR HEAVY RAIN. RUC AND HRRR CONTINUE TO SHOW THIS INTO THE EVENING HOURS MAINLY IN THE EASTERN ZONES. THREAT SHOULD END THEREAFTER. ON WEDNESDAY...DIURNAL HEATING WILL SPARK SHOWERS AND THUNDERSTORMS AGAIN AS UPPER LEVELS REMAIN UNSETTLED WITH LOW LEVEL WARMTH AND HUMIDITY. NOT CONFIDENT ENOUGH TO PIN-POINT WHERE HEAVY RAINS WILL OCCUR AND DIDN/T FEEL COMFORTABLE TO BROADBRUSH THIS. SMALL HAIL AND GUSTY WINDS ARE ALSO POSSIBLE BUT AGAIN DID NOT WANT TO BROADBRUSH...AND IT/S ALREADY MENTIONED IN THE HWO. BY THURSDAY...THE UPPER RIDGE BUILDS IN AND SUPPRESSES CONVECTION. WITH MORE SUNSHINE...TEMPERATURES WILL BE WARMER. AIRMASS WILL BE MORE HUMID OVER THE EASTERN ZONES BUT ANY THUNDERSTORM DEVELOPMENT WILL BE OVER THE DAKOTAS. TFJ .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... A GOOD CHUNK OF THE PREVIOUS FORECAST STILL STANDS... BUT A COUPLE PLACES NEEDED TWEAKING. FIRST... OVERNIGHT LOWS POST FRIDAY RIDGE NEEDED TO BE DRUG DOWN AS THEY WARMED FAR TOO FAST FOR SOUTHWEST FOLLOWED BY ZONAL FLOW ALOFT THROUGH EARLY NEXT WEEK. ALSO... ACTED TO STRIP OUT ZERO POPS FOR THE SAME TIME PERIOD AS VARIABILITY BEGINS TO CREEP INTO THE FORECAST POST SUNDAY AMOUNG OPERATIONAL EC VERSUS ITS ENSEMBLE MEMBERS... WHILE NO REAL ANALOGS FROM THE PAST 60 DAYS ARE YET AVAILABLE FOR THESE PERIODS. GAH PREVIOUS LONG TERM DISCUSSION... THE LONG TERM FORECAST PERIOD BEGINS WITH A STRONG UPPER LEVEL RIDGE IN PLACE WITH ITS AXIS DIRECTLY THROUGH NORTHEAST MONTANA. EXCELLENT MODEL AGREEMENT IN KEEPING THE ENTIRE CWA CONSEQUENTLY DRY. THIS WILL ALLOW THE HOTTEST TEMPERATURES OF THE SUMMER SEASON TO FINALLY ARRIVE...TOPPING OUT IN THE LOW TO MID 90S...ALTHOUGH SOME NUMERICAL GUIDANCE SUGGESTS THAT EVEN THIS MAY BE TOO CONSERVATIVE FOR FRIDAY AND SATURDAY HIGH TEMPERATURES. FOR NOW FELT IT WAS BEST TO SHOW A GRADUAL INCREASE UNTIL MORE MODEL CONSENSUS IS EVIDENT. WITH A COOL FRONT SET TO MOVE THROUGH THE AREA ON SATURDAY NIGHT...SCATTERED SHOWERS AND THUNDERSTORMS WILL BE ON THE HEELS OF SOME MUCH AWAITED NORTHWESTERLY SURFACE WINDS UNDER SOUTHWESTERLY FLOW ALOFT COURTESY OF THE UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST COASTAL AREA. THIS UNSETTLED PERIOD SHOULD REMAIN OVER THE REGION WHILE A SHORT WAVE TROUGH PUSHES THROUGH THE AREA THROUGH MONDAY MORNING...WITH THE BEST CHANCES FOR PRECIP FOCUSED FROM SATURDAY NIGHT THROUGH SUNDAY MORNING. MONDAY AND BEYOND...STRONG SUMMER RIDGING FROM THE SOUTHWEST MOVES IN AGAIN TO CUT OFF THE PRECIPITATION WITH TEMPERATURES WARMING BACK UP INTO THE 90S. && .AVIATION... FLIGHT CATEGORY: MAINLY VFR. MVFR POSSIBLE WITH THUNDER OR HAZE. THUNDER: THE EDGE OF A RIDGE WILL PROVIDE ENOUGH LIFT FOR SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP NEAR THE KOLF... KSDY... AND KGDV TERMINALS THIS AFTERNOON... HOWEVER CHANCES ARE NOT HIGH ENOUGH TO PLACE DIRECTLY IN THE TAFS. THEREFORE WILL GO WITH CB/S UNTIL KICK OFF TIME AROUND 18 TO 21Z AND AMEND AS NEEDED. AS USUAL... BRIEF VISIBILITY OBSCURATION AND SUDDEN GUSTY WINDS ARE POSSIBLE NEAR ANY THUNDERSTORM. HAZE: HAZE FROM FIRES TO THE WEST HAS REDUCED VISIBILITY TO WELL LESS THAN 20 MILES AT TIMES AND ACCORDING TO PREVIOUS OBSERVATIONS ON RARE OCCASIONS CAN REACH THE MVFR OBSCURATION OF 5 MILES. HOWEVER... THIS IS FAR TOO RARE TO PLACE IN THE TAFS DIRECTLY. WILL AMEND IF BECOMES NECESSARY. AREA WINDS: WINDS WILL BE OUT OF THE SOUTH AND EAST AROUND 10 KTS SUSTAINED... GUSTING UP TO 15 KTS DURING THE AFTERNOON. GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GLASGOW MT
918 AM MDT TUE AUG 13 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH THURSDAY... BEST INSTABILITY LATER TODAY SHOULD BE OCCURRING OVER THE EASTERN ZONES WHERE SURFACE BOUNDARY IS LOCATED. LEANED ON RUC AND HRRR WITH THE UPDATE AS THEY HAVE ACTIVITY IN THIS AREA. QUITE A BIT OF MOISTURE IN THE COLUMN THIS MORNING WITH 1.18" PRECIPITAL WATER...SO HEAVY RAIN WILL BE POSSIBLE WITH SLOW MOVING STORMS. REST OF FORECAST LOOKED GOOD. TFJ PREVIOUS DISCUSSION... A SLOW MOVING FRONTAL BOUNDARY WILL COMBINE WITH SHORTWAVES OVERTOPPING AN UPPER RIDGE AND MOIST UNSTABLE AIRMASS TO PRODUCE THUNDERSTORMS AT TIMES TODAY THROUGH WEDNESDAY NIGHT. WITH PRECIPITABLE WATER EXPECTED TO BE BETWEEN AN INCH AND 1.25 INCHES... LOCALLY HEAVY RAIN IS ALSO POSSIBLE WHICH MAY PRODUCE FLASH FLOODING. MODELS DIFFER IN WHEN AND WHERE IT WILL RAIN WITH THE INDIVIDUAL WAVES. WILL BROADBRUSH ISOLATED TO SCATTERED THUNDERSTORMS TODAY AND TONIGHT WITH HEAVY RAIN POSSIBLE FOLLOWED BY ISOLATED TO SCATTERED THUNDERSTORMS ON WEDNESDAY AND A CHANCE OF THUNDERSTORMS WEDNESDAY NIGHT. UPPER RIDGE STRENGTHENS OVER THE FORECAST AREA ON THURSDAY WITH SOMEWHAT DRIER... WARMER AND MORE STABLE AIRMASS WHICH WILL LIMIT THE CHANCES OF THUNDERSTORMS. WITH SHORTWAVE LACKING IN THE FLOW ALOFT... WILL GO WITH A DRY FORECAST FOR NOW. FORRESTER .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... THE LONG TERM FORECAST PERIOD BEGINS WITH A STRONG UPPER LEVEL RIDGE IN PLACE WITH ITS AXIS DIRECTLY THROUGH NORTHEAST MONTANA. EXCELLENT MODEL AGREEMENT IN KEEPING THE ENTIRE CWA CONSEQUENTLY DRY. THIS WILL ALLOW THE HOTTEST TEMPERATURES OF THE SUMMER SEASON TO FINALLY ARRIVE...TOPPING OUT IN THE LOW TO MID 90S...ALTHOUGH SOME NUMERICAL GUIDANCE SUGGESTS THAT EVEN THIS MAY BE TOO CONSERVATIVE FOR FRIDAY AND SATURDAY HIGH TEMPERATURES. FOR NOW FELT IT WAS BEST TO SHOW A GRADUAL INCREASE UNTIL MORE MODEL CONSENSUS IS EVIDENT. WITH A COOL FRONT SET TO MOVE THROUGH THE AREA ON SATURDAY NIGHT...SCATTERED SHOWERS AND THUNDERSTORMS WILL BE ON THE HEELS OF SOME MUCH AWAITED NORTHWESTERLY SURFACE WINDS UNDER SOUTHWESTERLY FLOW ALOFT COURTESY OF THE UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST COASTAL AREA. THIS UNSETTLED PERIOD SHOULD REMAIN OVER THE REGION WHILE A SHORT WAVE TROUGH PUSHES THROUGH THE AREA THROUGH MONDAY MORNING...WITH THE BEST CHANCES FOR PRECIP FOCUSED FROM SATURDAY NIGHT THROUGH SUNDAY MORNING. MONDAY AND BEYOND...STRONG SUMMER RIDGING FROM THE SOUTHWEST MOVES IN AGAIN TO CUT OFF THE PRECIPITATION WITH TEMPERATURES WARMING BACK UP INTO THE 90S. && .AVIATION... FLIGHT CATEGORY: MAINLY VFR. MVFR POSSIBLE WITH THUNDER OR HAZE. THUNDER: THE EDGE OF A RIDGE WILL PROVIDE ENOUGH LIFT FOR SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP NEAR THE KOLF... KSDY... AND KGDV TERMINALS THIS AFTERNOON... HOWEVER CHANCES ARE NOT HIGH ENOUGH TO PLACE DIRECTLY IN THE TAFS. THEREFORE WILL GO WITH CB/S UNTIL KICK OFF TIME AROUND 18 TO 21Z AND AMEND AS NEEDED. AS USUAL... BRIEF VISIBILITY OBSCURATION AND SUDDEN GUSTY WINDS ARE POSSIBLE NEAR ANY THUNDERSTORM. HAZE: HAZE FROM FIRES TO THE WEST HAS REDUCED VISIBILITY TO WELL LESS THAN 20 MILES AT TIMES AND ACCORDING TO PREVIOUS OBSERVATIONS ON RARE OCCASIONS CAN REACH THE MVFR OBSCURATION OF 5 MILES. HOWEVER... THIS IS FAR TOO RARE TO PLACE IN THE TAFS DIRECTLY. WILL AMEND IF BECOMES NECESSARY. AREA WINDS: WINDS WILL BE OUT OF THE SOUTH AND EAST AROUND 10 KTS SUSTAINED... GUSTING UP TO 15 KTS DURING THE AFTERNOON. GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1201 AM MDT Tue Aug 13 2013 .UPDATE... Increased POPS for the rest of the night for the northeast zones as showers and thunderstorms continue to develop along multiple outflow boundaries. Expect coverage of precipitation to begin decreasing in a few hours as the shortwave and associated lift move east. Langlieb && .AVIATION... UPDATED 0505Z. Scattered thunderstorms continue across central and north central MT from northeast of KGTF to east of KHVR, producing good amount of lightning and moderate to locally heavy rainfall. Storms have also been putting out gusty outflow winds of 25-35 kts. Storm cells are expected to gradually dissipate between now and 08Z with ceilings increasing to greater than 10000 ft at that time. Clear skies to scattered clouds and light winds expected overnight. Tuesday will be near-repeat of Monday`s weather as scattered thunderstorms develop again during the afternoon/evening. Waranauskas && .PREV DISCUSSION... /ISSUED 530 PM MDT Mon Aug 12 2013/ Tonight through Wednesday...Overall pattern has changed little from Sunday. The airmass is a bit more unstable this afternoon with CAPE values of 1000 to 2000 J/kg across the northern portion of the county warning area. Shear values, though not overly impressive, have also increased from earlier this morning and with high precipitable water, the result is thunderstorm development. The weak steering flow aloft will make very slow movers with these storms and heavy rain will be the primary threat (although some hail cannot be ruled out). HRRR and RUC analysis continue to develop thunderstorms over Great Falls as late as 04 to 05z. Drier conditions over southwest Montana will translate to isolated thunderstorms this evening. Enough instability will exist Tuesday afternoon to allow isolated to scattered thunderstorms to develop again though areal coverage should be less. Rising H5 heights Wednesday will herald the beginning of a drier and warmer regime. Temperatures will be near or slightly above seasonal averages. Emanuel Wednesday Night through Monday...Medium range forecast remains relatively unchanged tonight. Models are in good agreement from mid-week until early in the weekend and indicate that an upper level ridge will be over the Rocky Mountains for a very warm and generally dry forecast period. Model consensus for the weekend through early next week remains elusive. Models agree that the ridge will be pushed eastward on Saturday as a broad upper level trough moves inland along the west coast. Beyond Saturday, models set up a roughly zonal flow aloft but bring multiple and frequent short waves over the region. Unfortunately, the wave phase and speed differ markedly between the models and significant disagreement with regard to pops/clouds/weather timing arises. Am sticking with a solution that trends temperatures slightly cooler and increases pops toward climatology for the weekend through Monday. mpj && .PRELIMINARY POINT TEMPS/POPS... GTF 55 84 55 86 / 40 30 30 20 CTB 52 82 52 85 / 40 30 20 10 HLN 57 86 57 89 / 30 30 40 20 BZN 50 85 49 86 / 30 30 30 20 WEY 39 78 37 78 / 10 20 20 10 DLN 49 83 49 84 / 20 20 20 20 HVR 57 82 56 84 / 40 20 30 20 LWT 54 81 53 81 / 40 40 30 30 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Suk LONG TERM...mpj AVIATION...WARANAUSKAS weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1105 PM MDT Mon Aug 12 2013 AVIATION SECTION UPDATED .UPDATE... Increased pops and QPF across much of the eastern part of the zone as showers and thunderstorms continue to move across central Montana. The active weather pattern will continue through the evening hours with some of the shower activity lasting well past midnight. No significant changes to other parts of the forecast as most of the impact tonight will be associated with the severe thunderstorms. Suk && .AVIATION... UPDATED 0505Z. Scattered thunderstorms continue across central and north central MT from northeast of KGTF to east of KHVR, producing good amount of lightning and moderate to locally heavy rainfall. Storms have also been putting out gusty outflow winds of 25-35 kts. Storm cells are expected to gradually dissipate between now and 08Z with ceilings increasing to greater than 10000 ft at that time. Clear skies to scattered clouds and light winds expected overnight. Tuesday will be near-repeat of Monday`s weather as scattered thunderstorms develop again during the afternoon/evening. Waranauskas && .PREV DISCUSSION... /ISSUED 530 PM MDT Mon Aug 12 2013/ Tonight through Wednesday...Overall pattern has changed little from Sunday. The airmass is a bit more unstable this afternoon with CAPE values of 1000 to 2000 J/kg across the northern portion of the county warning area. Shear values, though not overly impressive, have also increased from earlier this morning and with high precipitable water, the result is thunderstorm development. The weak steering flow aloft will make very slow movers with these storms and heavy rain will be the primary threat (although some hail cannot be ruled out). HRRR and RUC analysis continue to develop thunderstorms over Great Falls as late as 04 to 05z. Drier conditions over southwest Montana will translate to isolated thunderstorms this evening. Enough instability will exist Tuesday afternoon to allow isolated to scattered thunderstorms to develop again though areal coverage should be less. Rising H5 heights Wednesday will herald the beginning of a drier and warmer regime. Temperatures will be near or slightly above seasonal averages. Emanuel Wednesday Night through Monday...Medium range forecast remains relatively unchanged tonight. Models are in good agreement from mid-week until early in the weekend and indicate that an upper level ridge will be over the Rocky Mountains for a very warm and generally dry forecast period. Model consensus for the weekend through early next week remains elusive. Models agree that the ridge will be pushed eastward on Saturday as a broad upper level trough moves inland along the west coast. Beyond Saturday, models set up a roughly zonal flow aloft but bring multiple and frequent short waves over the region. Unfortunately, the wave phase and speed differ markedly between the models and significant disagreement with regard to pops/clouds/weather timing arises. Am sticking with a solution that trends temperatures slightly cooler and increases pops toward climatology for the weekend through Monday. mpj && .PRELIMINARY POINT TEMPS/POPS... GTF 55 84 55 86 / 40 30 30 20 CTB 52 82 52 85 / 40 30 20 10 HLN 57 86 57 89 / 30 30 40 20 BZN 50 85 49 86 / 30 30 30 20 WEY 39 78 37 78 / 10 20 20 10 DLN 49 83 49 84 / 20 20 20 20 HVR 57 82 56 84 / 40 20 30 20 LWT 54 81 53 81 / 40 40 30 30 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Suk LONG TERM...mpj AVIATION...WARANAUSKAS weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
946 PM CDT WED AUG 14 2013 .SYNOPSIS... ISSUED AT 330 PM CDT WED AUG 14 2013 SHOWER AND THUNDERSTORM ACTIVITY CURRENTLY EXISTS ACROSS NORTH- CENTRAL NEBRASKA AND IS MOVING EASTWARD SLOWLY. NEBRASKA IS UNDER NORTHWEST FLOW ALOFT WITH AN UPPER LEVEL WAVE IN EASTERN NEBRASKA AND ANOTHER OVER MONTANA. LOW LEVEL FLOW IS GENERALLY SOUTHERLY WITH AN AREA OF LOW PRESSURE OVER THE INTERMOUNTAIN WEST AND HIGH PRESSURE OVER THE UPPER MISSISSIPPI RIVER VALLEY. A WEAK BOUNDARY EXISTS ACROSS CENTRAL NEBRASKA...RUNNING FROM HOLT COUNTY SOUTHWEST TO CHASE COUNTY. && .UPDATE... ISSUED AT 945 PM CDT WED AUG 14 2013 HAVE ADJUSTED PRECIPITATION CHANCES ACROSS THE AREA NOW THAT ISOLATED CONVECTION HAS ENDED ACROSS THE AREA...FOR NOW. HOWEVER...CONVECTIVE COMPLEXES REMAIN ACROSS SOUTHWEST SD AND NORTHEAST CO. HRRR DOES TRY TO KEEP THE SD COMPLEX TOGETHER LONG ENOUGH TO MOVE INTO THE PANHANDLE AND INTO THE CENTRAL SANDHILLS. MID LEVEL LAPSE RATES WOULD SUPPORT SOME ADDITIONAL DEVELOPMENT SO HAVE LEFT SMALL CHANCES IN FOR NOW. OTHERWISE ADDED SOME PATCHY FOG EAST OF HIGHWAY 83 WHERE SMALL TEMP/DEW POINT SPREADS EXIST. UPDATE ISSUED AT 706 PM CDT WED AUG 14 2013 HAVE UPDATED EVENING FCST TO SLIGHTLY ADJUST PRECIP CHANCES. THUNDERSTORMS SHOWING A QUICK DECREASE IN COVERAGE AND INTENSITY OVER THE LAST 15 MINS. ADDITIONAL CONVECTION FURTHER WEST WILL APPROACH THE AREA LATER THIS EVENING...BUT OVERALL MID LEVEL LAPSE RATES DOES NOT LOOK FAVORABLE AT THIS POINT BUT WILL LOOK FURTHER INTO THIS. OTHERWISE REMAINDER OF FCST LOOKS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 THE THUNDERSTORM COMPLEX THAT STARTED OVER THE NORTHEAST HAS LINGERED THERE TODAY DUE TO A FAVORABLE LOW LEVEL JET...SOME MODEST ELEVATED CAPE...AND UPPER SUPPORT. A SURFACE BOUNDARY CURRENTLY RUNS FROM HOLT TO CHASE COUNTIES AND MAY BE THE FOCUS FOR A FEW THUNDERSTORMS THIS AFTERNOON/EVENING. THE SEVERE THREAT IS LOW AS DEEP SHEAR IS RUNNING AT 25 TO 30 KTS. AN ISOLATED SEVERE STORM OR TWO CANNOT BE RULED OUT...HOWEVER. AN UPPER LEVEL WAVE WILL PUSH INTO THE AREA FROM THE NORTHWEST LATE TONIGHT AND TOMORROW MORNING. AHEAD OF THIS WAVE...CLOUDS WILL INCREASE AND SO WILL A LOW LEVEL JET ACROSS WESTERN NEBRASKA. BELIEVE THERE MAY BE SOME LATE NIGHT THUNDERSTORMS ACROSS THE NORTHWEST LATE IN THE NIGHT AND EARLY TOMORROW MORNING. THE MAIN UPPER WAVE WILL DRIFT INTO CENTRAL NEBRASKA BY MIDDAY...AND SO BELIEVE ANY THUNDERSTORM ACTIVITY WOULD BE PRIMARILY DURING THE LATE MORNING TO AFTERNOON HOURS. SHEAR TOMORROW IS A LITTLE BETTER...30-35 KTS...ACROSS THE SOUTH. AS A RESULT...SPC HAS ISSUED A SLIGHT RISK FOR SEVERE WEATHER ACROSS THAT AREA FOR TOMORROW. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 FORECASTING CHALLENGES ARE LINGERING PRECIPITATION THURSDAY EVENING...FOG POTENTIAL OVERNIGHT THURSDAY NIGHT INTO FRIDAY MORNING...THEN TEMPERATURES. WITH RESPECT TO THUNDERSTORM CHANCES THURSDAY EVENING...THE MODELS ARE A LITTLE FASTER WITH SHORTWAVE ENERGY DROPPING SOUTH THURSDAY ACROSS THE DAKOTAS AND NEBRASKA. THIS WILL BRING AN EARLIER END TO PRECIPITATION BY LATE THURSDAY EVENING IN THE SRN CWA. BEHIND THE EXITING CONVECTION...CLEARING SKIES...STRONG RADIATIONAL COOLING AND MOIST BOUNDARY LAYER CONDS MAY LEAD TO THE FORMATION OF FOG OVERNIGHT THURSDAY NIGHT INTO EARLY FRIDAY MORNING. NAM AND GFS BUFR SOUNDINGS INDICATE A FAVORABLE ENVIRONMENT FOR FOG FORMATION...AS DOES THE MET AND MAV GUIDANCE ALONG AND SOUTH OF A LINE FROM BIG SPRINGS TO BARTLETT. DECIDED TO LEAVE FOG MENTION AS PATCHY ATTM...AS SREF PROBABILITIES ARE RUNNING AROUND 60 PERCENT FOR VISBYS BLO 1SM. FOR FRIDAY INTO SUNDAY NIGHT...RIDGING WILL BUILD EAST INTO THE CENTRAL AND NORTHERN PLAINS...LEADING TO NRLY FLOW ALOFT AND EFFECTIVELY CUTTING OFF ANY CHANCE FOR PCPN FRIDAY THROUGH SUNDAY. HIGHS WILL BEGIN TO CLIMB FROM THE LOWER TO MID 80S ON FRIDAY...TO THE MID 80S TO AROUND 90 BY THE END OF THE WEEKEND. FOR HIGHS AND LOWS...UTILIZED THE ADJMAV GUIDANCE AS IT HAS HAD THE BEST VERIFICATION OVER THE PAST COUPLE OF WEEKS AND AVOIDED THE HIGHER MEX NUMBERS WHICH HAD HIGHS IN THE 90S BY SUNDAY INTO MONDAY. THINKING ATTM IS THAT THE MEX NUMBERS ARE TOO HIGH GIVEN THE HIGH DEGREE OF SURFACE MOISTURE ACROSS THE AREA. RIDGING ALOFT WILL BEGIN TO BREAK DOWN SLIGHTLY EARLY NEXT WEEK AS A DISTURBANCE TRACKS ACROSS SRN CANADA. THIS FEATURE HAS TRENDED WEAKER COMPARED TO YESTERDAYS MODEL RUNS...WHICH A...FACILITATES DECREASED POPS NEXT WEEK...AND B...INCREASED HIGH TEMPS...BOTH OF WHICH WERE IMPLEMENTED WITH THIS FORECAST PACKAGE. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 706 PM CDT WED AUG 14 2013 AVIATION FCST CHALLENGES ARE TSRA CHCS THIS EVENING AND FG/BR POTENTIAL TWD DAYBREAK...MUCH AS THEY HAVE BEEN LAST COUPLE OF DAYS. FIRST FOR TSRA CHANCES...BEST POTENTIAL WOULD BE IN THE SOUTHEAST PORTION OF THE AREA...BUT EVEN THAT LOOKS WANING QUICKLY. WILL BE MONITORING TSRA MOVING IN FROM FURTHER WEST...BUT CONVECTION ALLOWING MODELS ARE NOT FAVORABLE FOR THESE AREAS HOLDING TOGETHER. NEXT CHALLENGE IS BR/FG POTENTIAL. ONCE AGAIN THE SIGNAL IN THE MODELS IS MIXED AND THEREFORE CONFIDENCE IS LOW. STILL HAVE INCLUDED A MENTION OF SCT LOW CIGS AND SOME BR...THOUGH KEEPING VSBYS AT IFR OR ABOVE. TSRA CHCS RETURN AGAIN TMRW AFTERNOON AS SIGNIFCANT PV ANOMALY ROTATING SEWD INTO THE HIGH PLAINS. AT THIS POINT COVERAGE MAY BE IN QUESTION...AND MODELS HAVE GENERALLY BEEN OVERDOING THIS THE LAST COUPLE OF NIGHTS. CONFIDENCE IS LOW...AND HAVE LEFT TSRA MENTION OUT OF TAFS FOR THIS TIME FRAME. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JWS SYNOPSIS...KNUTSVIG SHORT TERM...KNUTSVIG LONG TERM...CLB AVIATION...JWS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
619 PM CDT WED AUG 14 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 CLOUDS LINGERED ACROSS MUCH OF THE AREA THIS AFTERNOON AND HAS SO FAR HELPED TO PUT A CAP ON MORE WIDESPREAD CONVECTION. THAT SAID...INSTABILITY IS BEGINNING TO BUILD...AND WITH SOME NOTABLE MOISTURE CONVERGENCE AHEAD OF DEVELOPING CONVECTION TO OUR NORTH...EXPECT THE POTENTIAL FOR ADDITIONAL DEVELOPMENT THROUGH THE LATE AFTERNOON AND EVENING HOURS. MODELS HAVE NOT HAD A GREAT HANDLE ON THIS ALL DAY...ALBEIT 12Z WRF AND LATEST HRRR BOTH ATTEMPTED TO PICK UP ON CONVECTION TO OUR NORTH...TAKING IT SOUTHWARD THROUGH THE EVENING HOURS. WHILE CONFIDENCE IS NOT PARTICULARLY HIGH...CONTINUE TO SEE THE POTENTIAL FOR SOME ADDITIONAL THUNDERSTORM ACTIVITY THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS AS THERE IS PLENTY OF INSTABILITY TO TAP...ESPECIALLY WEST OF HIGHWAY 281. THAT SAID...SHEAR IS VERY WEAK...AND ANY ADDITIONAL STORMS THAT DO DEVELOP ARE NOT EXPECTED TO BE SEVERE OR WIDESPREAD. AS WE WORK TOWARDS THURSDAY MORNING AND FOCUS OF INITIAL CONVECTION SHIFTS SOUTHWARD...COULD SEE SOME PARTIAL CLEARING...AND WITH LIGHT SOUTHEASTERLY WINDS AND ELEVATED LOW LEVEL MOISTURE...DECIDED TO INSERT PATCHY FOG INTO THE FORECAST FOR THE EARLY MORNING HOURS TOMORROW. LATEST HRRR IS INDICATING POSSIBLY SOME DENSE FOG ACROSS OUR NORTH BY 09Z...BUT WITH UNCERTAINTY IN TIMING AND AMOUNT OF CLEARING...PATCHY MENTION SEEMED MORE REASONABLE FOR THE TIME BEING. AS WE WORK INTO THE DAYTIME HOURS THURSDAY...THE POTENTIAL FOR SOME STRONG/MARGINALLY SEVERE STORMS WILL BE REALIZED BY EARLY AFTERNOON AS MODELS ARE PICKING UP ON AN UPPER LEVEL SHORTWAVE DROPPING DOWN FROM THE NORTH COUPLED WITH THE PRESENCE OF A WEAK WARM FRONTAL BOUNDARY DRAPED ACROSS THE LOCAL AREA FROM NORTHWEST TO SOUTHEAST. THIS COMBINATION...WITH PLENTY OF AVAILABLE INSTABILITY...SHOULD MAKE FOR A MORE ACTIVE AFTERNOON AND EVENING...AND CONTINUED WITH MENTION OF POTENTIAL SEVERE WEATHER IN HWO THIS AFTERNOON. WHILE SHEAR IS NOT ALL THAT IMPRESSIVE...CAPE AND FORCING SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF A FEW STORMS WITH MARGINALLY SEVERE HAIL AND THUNDERSTORM WIND GUSTS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 THURSDAY NIGHT THROUGH WEDNESDAY. MAIN FORECAST CONCERNS WILL BE CHANCES FOR THUNDERSTORMS ON AND OFF THROUGH THE PERIOD AND TEMPERATURES. AN UPPER LEVEL WAVE WILL CONTINUE TO MOVE THROUGH THE AREA THURSDAY NIGHT. THUNDERSTORMS WILL CONTINUE ACROSS THE AREA DURING THE EVENING BUT GRADUALLY COME TO AN END FROM NORTHWEST TO SOUTHEAST DURING THE OVERNIGHT HOURS AND INTO FRIDAY MORNING. MUCAPE REMAINS AROUND 3000 J/KG DURING THE EVENING BUT DROPS OFF LATER IN THE NIGHT. ON FRIDAY THE UPPER LEVEL RIDGE IN THE ROCKIES STARTS TO SLIDE TO THE EAST AND WITH THE RAIN MOVING OUT...TEMPERATURES WILL WARM SOME. FRIDAY NIGHT INTO SUNDAY THE UPPER LEVEL RIDGE BUILDS ACROSS THE AREA AND EXPECT DRY CONDITIONS AND TEMPERATURES WILL CONTINUE TO WARM A FEW DEGREES. AN UPPER LEVEL WAVE WILL MOVE OVER THE RIDGE SUNDAY NIGHT AND BRING A SMALL CHANCE FOR THUNDERSTORMS. THERE SHOULD BE A BRIEF BREAK FROM THUNDERSTORMS AGAIN ON MONDAY BUT ANOTHER UPPER LEVEL WAVE MOVES INTO THE AREA MONDAY NIGHT AND TUESDAY. THERE IS ALSO A WEAK COLD FRONT THAT MOVES THROUGH THE FORECAST AREA MONDAY NIGHT. THUNDERSTORMS ARE EXPECTED ALONG AND BEHIND THE COLD FRONT. DESPITE THE COLD FRONT TEMPERATURES SHOULD CONTINUE TO WARM A DEGREE OR TWO EACH DAY AS THE UPPER RIDGE SETTLES OVER THE PLAINS. TUESDAY NIGHT AND WEDNESDAY THE MODELS HAVE SOME DIFFERENCES IN THE MAIN PATTERN. THE GFS HAS AN UPPER RIDGE...WHILE THE ECMWF HAS A TROUGH MOVING THROUGH. WILL HAVE A SMALL CHANCE FOR THUNDERSTORMS FOR NOW. THE TEMPERATURE SHOULD REMAIN ABOVE NORMAL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 613 PM CDT WED AUG 14 2013 THUNDERSTORMS NORTH OF THE TERMINAL HAVE SHOWN SIGNS OF WEAKENING EARLY THIS EVENING AND HAVE NOT INCLUDED IN THE TAF ATTM...AND WILL MONITOR. SOME POTENTIAL EXISTS FOR FOG DEVELOPMENT LATE TONIGHT INTO THURSDAY MORNING AND HAVE KEPT VSBYS AT MVFR FOR NOW. REDEVELOPMENT OF CONVECTION IS FORECAST FOR THURSDAY AFTN/EVE OR THE LATTER TAF HOURS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...SAR LONG TERM...JCB AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
520 PM CDT TUE AUG 13 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 400 PM CDT TUE AUG 13 2013 WE HAD A MESOSCALE CONVECTIVE VORTEX (MCV) TRACK ACROSS OUR FORECAST AREA THIS MORNING INTO THE EARLY AFTERNOON HOURS. THIS BROUGHT WIDESPREAD RAINFALL TO OUR FORECAST AREA AND HAS WORKED OVER THE ATMOSPHERE ENOUGH THAT ADDITIONAL PRECIPITATION THIS EVENING INTO TONIGHT IS UNLIKELY. THE CONVECTION THAT TRACKED THROUGH OUR AREA HAS NOW PASSED SOUTH INTO CENTRAL KANSAS AND NEW STORMS HAVE ALSO FORMED TO OUR WEST OVER THE HIGH PLAINS OF WESTERN NEBRASKA. THE WESTERN NEBRASKA THUNDERSTORMS HAVE FORMED ALONG THE LEADING EDGE OF THE NEXT SHORTWAVE THAT IS TRACKING SOUTHEAST FROM EASTERN WYOMING/SOUTHWEST SOUTH DAKOTA INTO WESTERN NEBRASKA. DEEP MOISTURE CONVERGENCE AND AFTERNOON DESTABILIZATION IS ALSO MAXIMIZED ACROSS WESTERN NEBRASKA INTO THE BLACK HILLS AND THIS IS WHERE ADDITIONAL THUNDERSTORMS ARE EXPECTED TO FORM THIS EVENING. THIS IS A WEAKLY SHEARED ENVIRONMENT AND STORM PROPAGATION WILL GENERALLY BE A SLOW DRIFT TO THE SOUTH...WHICH SHOULD KEEP THE WESTERN STORMS JUST TO THE WEST OF OUR FORECAST AREA TONIGHT. THERE IS AN OUTSIDE CHANCE OF OUR WESTERN ZONES SEEING A PREDAWN SHOWER/THUNDERSTORM SHOULD THE BLACK HILLS CONVECTION MAKE IT THIS FAR SOUTHEAST. HOWEVER...MOST FORECAST MODEL DATA KEEPS ALL CONVECTION WEST OF OUR FORECAST AREA TONIGHT AND THUS WE WILL KEEP ALL ZONES DRY TONIGHT...WHILE KEEPING AN EYE ON THE WEST FOR THE POSSIBILITY OF NEEDING TO THROW SOME POPS IN THE FORECAST DEPENDING ON FUTURE RADAR TRENDS. THERE IS SOME POTENTIAL OF FOG TONIGHT GIVEN THE RECENT WIDESPREAD RAINFALL. HOWEVER...FORECAST MODELS ARE MIXED ON FOG POTENTIAL WITH THE HRRR MORE FAVORABLE FOR FOG WHILE THE SREF WOULD NOT GIVE US ANY FOG. ULTIMATELY FOG WILL LARGELY HINGE ON CLOUD COVER AND SUBSEQUENT COOLING. HAVE LEFT FOG OUT OF THE FORECAST FOR NOW...BUT SHOULD WE CLEAR OUT AND REMAIN CLEAR THROUGH MOST OF THE NIGHT...THEN COOLING MIGHT BE ADEQUATE FOR SOME AREAS OF FOG EARLY WEDNESDAY MORNING. WEDNESDAY...A SHORT WAVE TROUGH WILL TRACK SOUTHEAST ACROSS WESTERN NEBRASKA. INSTABILITY AND DEEP LAYER SHEAR WILL BE FAIRLY WEAK TO MODEST AT BEST AND THUS AM NOT EXPECTING SEVERE WEATHER...BUT CAN NOT RULE OUT A COUPLE OF STRONG THUNDERSTORMS IN ASSOCIATION WITH PEAK AFTERNOON HEATING. THE BEST CHANCE OF THUNDERSTORMS WILL BE ACROSS OUR WESTERN ZONES AND TO THE WEST OF OUR FORECAST AREA IN ASSOCIATION WITH THE APPROACHING SHORTWAVE. TEMPERATURES WILL REMAIN COOL FOR AUGUST DUE TO A CONTINUATION OF THE COOL AIRMASS OVERHEAD...CLOUDS...AND POSSIBLE PRECIPITATION. HIGHS WILL GENERALLY BE IN THE UPPER 70S TO LOWER 80S. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 400 PM CDT TUE AUG 13 2013 THE MAIN HIGHLIGHTS OF THIS 6-DAY PERIOD ARE A CONTINUATION OF CHALLENGING SHOWER/THUNDERSTORM CHANCES IN THE WED NIGHT THROUGH FRIDAY TIME FRAME WHICH MIGHT EVEN FEATURE A STRONG-SEVERE STORM THREAT CENTERED ON THURSDAY...FOLLOWED BY WHAT APPEARS TO BE A PREDOMINANTLY DRY WEEKEND...AND THEN A RETURN TO VERY UNCERTAIN RAIN CHANCES IN THE SUNDAY NIGHT-TUESDAY TIME FRAME AS THE PATTERN CHANGES A BIT. ITS BEEN A TOUGH GO OF IT LATELY TRYING TO DETERMINE HOW HARD TO HIT...OR BACK OFF...POPS EVEN IN THE FIRST 24 HOURS...SO THESE UNCERTAINTIES CONTINUE TO BE MAGNIFIED EVEN IN THE DAY 2-3 TIME FRAME. OF HIGHER CONFIDENCE IS THAT A FAIRLY REMARKABLE RUN OF SUB-90 DEGREE TEMPS WILL CONTINUE...WITH THE MAJORITY OF THE CWA FORECAST TO TOP OUT IN THE LOW-MID 80S DURING THIS TIME FRAME...WITH KS ZONES AS USUAL MOST FAVORED TO REACH UPPER 80S ON A FEW DAYS. AS FOR LOW TEMPS...EVERY NIGHT IS EXPECTED TO BE FAIRLY SIMILAR AND RATHER UNIFORM ACROSS THE CWA...EITHER IN THE LOW OR MID 60S. STARTING OFF WEDNESDAY EVENING/NIGHT...GAVE A BEST-STAB AT TWO 6-HOUR POP BLOCKS HEAVILY BASED ON MET/MAV GUIDANCE BLEND...WITH THE EVENING PERIOD FEATURING 20S-40S...AND THE LATE NIGHT PERIOD RANGING FROM ONLY 20S FAR WEST TO 50S IN EASTERN-MOST NEB ZONES. IN OTHER WORDS...THERE IS A DECENT CHANCE THAT PARTS OF THE CWA WILL SEE RAIN...BUT CONFIDENCE IN TIMING/PLACEMENT PRECLUDES LIKELY POPS ANYWHERE YET. ON THE LARGE-SCALE ALOFT...LEGITIMATE NORTHWEST-FLOW IS IN PLACE OVER THE CENTRAL PLAINS...BETWEEN A RIDGE AXIS EXTENDING NORTHWARD ACROSS THE ROCKIES FROM NORTHERN MEXICO INTO SOUTHWEST CANADA...AND A BROAD TROUGH ANCHORED OVER SOUTHEAST CANADA/THE NORTHEAST CONUS. ON A MORE LOCAL/REGIONAL LEVEL...THE CWA IS PROGGED TO REMAIN UNDER/NEAR THE MAIN TRACK OF LOW-AMPLITUDE SHORTWAVE TROUGHS RIPPLING THROUGH THE NORTHWEST FLOW. STARTING OFF RIGHT AWAY WED EVENING AT 00Z/7PM...ITS EXPECTED THAT AT LEAST A SMALL PART OF THE CWA SHOULD BE SEEING ACTIVITY PERSISTING FROM THE LATE AFTERNOON HOURS...ALTHOUGH MODEL QPF/REFLECTIVITY FIELDS VARY CONSIDERABLY ON THE MOST FAVORED AREA. AS THE NIGHT WEARS ON...THERE IS A DECENT SIGNAL FOR WARM AIR ADVECTION/MOISTURE TRANSPORT IN THE 850-700 MILLIBAR LAYER...WITHIN THE AXIS OF A MODEST 20+KT SOUTHWESTERLY LOW LEVEL JET. PER THE 12Z/18Z NAM AND LAST FEW SREF RUNS...THIS WOULD FAVOR EASTERN ZONES FOR THE HIGHEST LATE NIGHT POPS...WHILE THE ECWMF/GFS WOULD MORE-SO FAVOR CENTRAL/SOUTHWEST ZONES. AS FOR THUNDERSTORM INTENSITY...ALTHOUGH NOT EXPECTING A WIDESPREAD NOCTURNAL SEVERE THREAT...CERTAINLY A FEW STRONG TO MARGINALLY SEVERE STORMS WITH MAINLY A HAIL/LOCALLY HEAVY RAIN THREAT CANNOT BE RULED OUT GIVEN MUCAPE INCREASING TO AT LEAST 500-1000 J/KG IN THE PRESENCE OF AROUND 25KT OF DEEP LAYER SHEAR. THURSDAY/THURSDAY NIGHT...THIS 24 HOURS WOULD APPEAR TO CONTAIN THE OVERALL-HIGHEST THREAT OF SEVERE STORMS DURING THE NEXT SEVERAL DAYS...ALTHOUGH THE JURY IS STILL OUT ON WHETHER IT WOULD BE MORE LOCALIZED OR MORE WIDESPREAD. CERTAINLY WOULD NOT BE SURPRISED TO SEE THE UPCOMING SPC DAY 2 OUTLOOK INTRODUCE A SLIGHT RISK FOR ALL/PART OF THE CWA...MAINLY FOR THE AFTERNOON/EVENING HOURS. IN THE BIG PICTURE...SEASONABLY STRONG/SHARP NORTHWEST FLOW STRENGTHENS AB IT...AS MODELS ARE IN DECENT AGREEMENT IN DRIVING A BIT STRONGER/ORGANIZED SHORTWAVE TROUGH SOUTHWARD OUT OF WESTERN SD ACROSS THE HEART OF CENTRAL NEB/KS. FOR THE MORNING HOURS...KEPT POPS AT SLIGHT 20S EXCEPT 30S IN THE EAST WHERE SEEMINGLY THE BEST CHANCE OF LINGERING OVERNIGHT CONVECTION WOULD BE. THEN HAVE 30 POPS NEARLY ALL AREAS DURING THE AFTERNOON TO ACCOUNT FOR THUNDERSTORM REDEVELOPMENT AND/OR RE-INTENSIFICATION...ASSUMING OF COURSE THAT SUFFICIENT HEATING CAN TAKE PLACE. ITS STILL TOO SOON TO TELL THOUGH WHETHER POTENTIALLY VIGOROUS AFTERNOON ACTIVITY MAINLY DEVELOPS LOCALLY OR MOVES IN FROM THE NORTHWEST. AT ANY RATE...THE 18Z NAM DEPICTS A FAIRLY POTENT NORTHWEST FLOW SEVERE ENVIRONMENT WITH MIXED LAYER CAPE 2000+ J/KG IN THE PRESENCE OF DECENT 30-40 KNOT DEEP LAYER SHEAR...MAKING A FEW SUPERCELLS A POSSIBILITY IF THE MESOSCALE FEATURES COME TOGETHER. FOR THURSDAY EVENING/NIGHT...KEPT 30-50 POPS GOING AREA-WIDE...HIGHEST IN THE FAR SOUTH. NOT ACCOUNTING FOR POSSIBLE CONVECTIVE EFFECTS...BREEZES DURING THE DAY THURSDAY ARE EXPECTED TO AVERAGE AROUND 10 MPH FROM THE SOUTH. FRIDAY/FRIDAY NIGHT...THE LATEST NAM/GFS ARE IN GOOD AGREEMENT AMPLIFYING THE WESTERN CONUS RIDGE EASTWARD OVER THE CENTRAL PLAINS...RESULTING IN MODEST HEIGHT RISES AND NEARLY DUE-NORTHERLY FLOW ALOFT. THIS SHOULD RESULT IN A LESS-FAVORABLE ENVIRONMENT FOR THUNDERSTORM DEVELOPMENT. HOWEVER...KEPT THE MAJORITY OF THE CWA WITH SLIGHT POPS DURING THE DAYTIME HOURS MAINLY TO ACCOUNT FOR POSSIBLE DIURNAL-HEATING INDUCED CONVECTION...BUT LEFT FRIDAY NIGHT DRY PER PREVIOUS FORECAST. SATURDAY THROUGH SUNDAY...KEPT THE DRY FORECAST GOING CWA- WIDE...AS SEEMINGLY-BENIGN NORTHERLY FLOW REMAINS IN PLACE ALOFT TO THE EAST OF THE ROCKIES-CENTERED RIDGE AXIS. BOTH THE ECWMF/GFS KEEP THE MAIN BRANCHES OF STRONGER FLOW ALOFT WELL NORTH NEAR THE CANADIAN BORDER...AND ALSO IN THE SOUTHEAST STATES...WITH THE CWA ALSO STAYING SAFELY NORTHWEST OF A STALLED...POSSIBLY RETROGRADING CLOSED MID LEVEL LOW OVER THE SOUTHERN MO/AR AREA ADVERTISED MORE SO BY THE ECMWF THAN THE GFS. NOT READY TO GUARANTEE A DRY WEEKEND YET...BUT AT LEAST FOR NOW POPS HAVE BEEN KEPT IN THE SILENT 5-10 RANGE. GIVEN THAT THE AREA HAS SEEN VERY LITTLE IN THE WAY OF NON- CONVECTIVE BREEZE LATELY...ITS WORTH NOTING THAT THE CURRENT SUNDAY FORECAST ACTUALLY HAS SUSTAINED SOUTHERLY SPEEDS UP AROUND 15 MPH/GUSTS AROUND 20 MPH. SUNDAY NIGHT THROUGH TUESDAY MARKS THE RETURN OF VARIOUS...LOW- CONFIDENCE THUNDERSTORM CHANCES OF THE 20-30 PERCENT VARIETY...THAT WILL UNDOUBTEDLY BE REFINED SEVERAL TIMES DURING THE NEXT SEVERAL DAYS. FROM A GENERAL...SYNOPTIC SCALE STANDPOINT...BOTH THE ECWMF/GFS BREAK DOWN THE RIDGE-DOMINATED PATTERN FROM THE WEEKEND AND GRADUALLY BRINGS A QUASI-ZONAL PATTERN AS ONE OR TWO FAIRLY LOW-AMPLITUDE SHORTWAVE TROUGHS OF NOTE WORK INTO THE CENTRAL PLAINS FROM THE WEST. THIS SHOULD SUPPORT A CONTINUED SURFACE PATTERN OF LIGHT BUT NOTICEABLY SOUTHERLY BREEZES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 520 PM CDT TUE AUG 13 2013 THE MAIN CONCERN FOR THE TAF PERIOD IS THE POTENTIAL FOR FOG TONIGHT...THEN TIMING OF THUNDERSTORMS ON WEDNESDAY. CONVECTION REMAINS WELL WEST OF THE TERMINAL THIS EVENING AND GENERALLY EXPECT THE DRY CONDITIONS TO PERSIST UNTIL WEDNESDAY AFTERNOON. WITH WET GROUND AND DECREASING CLOUDS THIS EVENING...THERE IS SOME POTENTIAL FOR FOG DEVELOPMENT AND MODELS ARE NOT IN COMPLETE ON HOW DENSE FOG MAY BE AND HAVE JUST TRENDED WITH MVFR VSBYS TO START. AN UPPER LEVEL DISTURBANCE WILL CROSS NEB ON WEDNESDAY CHCS FOR TSTMS INCREASING AGAIN BY MID/LATE AFTN. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...WESELY LONG TERM...PFANNKUCH AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
401 PM CDT TUE AUG 13 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 400 PM CDT TUE AUG 13 2013 WE HAD A MESOSCALE CONVECTIVE VORTEX (MCV) TRACK ACROSS OUR FORECAST AREA THIS MORNING INTO THE EARLY AFTERNOON HOURS. THIS BROUGHT WIDESPREAD RAINFALL TO OUR FORECAST AREA AND HAS WORKED OVER THE ATMOSPHERE ENOUGH THAT ADDITIONAL PRECIPITATION THIS EVENING INTO TONIGHT IS UNLIKELY. THE CONVECTION THAT TRACKED THROUGH OUR AREA HAS NOW PASSED SOUTH INTO CENTRAL KANSAS AND NEW STORMS HAVE ALSO FORMED TO OUR WEST OVER THE HIGH PLAINS OF WESTERN NEBRASKA. THE WESTERN NEBRASKA THUNDERSTORMS HAVE FORMED ALONG THE LEADING EDGE OF THE NEXT SHORTWAVE THAT IS TRACKING SOUTHEAST FROM EASTERN WYOMING/SOUTHWEST SOUTH DAKOTA INTO WESTERN NEBRASKA. DEEP MOISTURE CONVERGENCE AND AFTERNOON DESTABILIZATION IS ALSO MAXIMIZED ACROSS WESTERN NEBRASKA INTO THE BLACK HILLS AND THIS IS WHERE ADDITIONAL THUNDERSTORMS ARE EXPECTED TO FORM THIS EVENING. THIS IS A WEAKLY SHEARED ENVIRONMENT AND STORM PROPAGATION WILL GENERALLY BE A SLOW DRIFT TO THE SOUTH...WHICH SHOULD KEEP THE WESTERN STORMS JUST TO THE WEST OF OUR FORECAST AREA TONIGHT. THERE IS AN OUTSIDE CHANCE OF OUR WESTERN ZONES SEEING A PREDAWN SHOWER/THUNDERSTORM SHOULD THE BLACK HILLS CONVECTION MAKE IT THIS FAR SOUTHEAST. HOWEVER...MOST FORECAST MODEL DATA KEEPS ALL CONVECTION WEST OF OUR FORECAST AREA TONIGHT AND THUS WE WILL KEEP ALL ZONES DRY TONIGHT...WHILE KEEPING AN EYE ON THE WEST FOR THE POSSIBILITY OF NEEDING TO THROW SOME POPS IN THE FORECAST DEPENDING ON FUTURE RADAR TRENDS. THERE IS SOME POTENTIAL OF FOG TONIGHT GIVEN THE RECENT WIDESPREAD RAINFALL. HOWEVER...FORECAST MODELS ARE MIXED ON FOG POTENTIAL WITH THE HRRR MORE FAVORABLE FOR FOG WHILE THE SREF WOULD NOT GIVE US ANY FOG. ULTIMATELY FOG WILL LARGELY HINGE ON CLOUD COVER AND SUBSEQUENT COOLING. HAVE LEFT FOG OUT OF THE FORECAST FOR NOW...BUT SHOULD WE CLEAR OUT AND REMAIN CLEAR THROUGH MOST OF THE NIGHT...THEN COOLING MIGHT BE ADEQUATE FOR SOME AREAS OF FOG EARLY WEDNESDAY MORNING. WEDNESDAY...A SHORT WAVE TROUGH WILL TRACK SOUTHEAST ACROSS WESTERN NEBRASKA. INSTABILITY AND DEEP LAYER SHEAR WILL BE FAIRLY WEAK TO MODEST AT BEST AND THUS AM NOT EXPECTING SEVERE WEATHER...BUT CAN NOT RULE OUT A COUPLE OF STRONG THUNDERSTORMS IN ASSOCIATION WITH PEAK AFTERNOON HEATING. THE BEST CHANCE OF THUNDERSTORMS WILL BE ACROSS OUR WESTERN ZONES AND TO THE WEST OF OUR FORECAST AREA IN ASSOCIATION WITH THE APPROACHING SHORTWAVE. TEMPERATURES WILL REMAIN COOL FOR AUGUST DUE TO A CONTINUATION OF THE COOL AIRMASS OVERHEAD...CLOUDS...AND POSSIBLE PRECIPITATION. HIGHS WILL GENERALLY BE IN THE UPPER 70S TO LOWER 80S. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 400 PM CDT TUE AUG 13 2013 THE MAIN HIGHLIGHTS OF THIS 6-DAY PERIOD ARE A CONTINUATION OF CHALLENGING SHOWER/THUNDERSTORM CHANCES IN THE WED NIGHT THROUGH FRIDAY TIME FRAME WHICH MIGHT EVEN FEATURE A STRONG-SEVERE STORM THREAT CENTERED ON THURSDAY...FOLLOWED BY WHAT APPEARS TO BE A PREDOMINANTLY DRY WEEKEND...AND THEN A RETURN TO VERY UNCERTAIN RAIN CHANCES IN THE SUNDAY NIGHT-TUESDAY TIME FRAME AS THE PATTERN CHANGES A BIT. ITS BEEN A TOUGH GO OF IT LATELY TRYING TO DETERMINE HOW HARD TO HIT...OR BACK OFF...POPS EVEN IN THE FIRST 24 HOURS...SO THESE UNCERTAINTIES CONTINUE TO BE MAGNIFIED EVEN IN THE DAY 2-3 TIME FRAME. OF HIGHER CONFIDENCE IS THAT A FAIRLY REMARKABLE RUN OF SUB-90 DEGREE TEMPS WILL CONTINUE...WITH THE MAJORITY OF THE CWA FORECAST TO TOP OUT IN THE LOW-MID 80S DURING THIS TIME FRAME...WITH KS ZONES AS USUAL MOST FAVORED TO REACH UPPER 80S ON A FEW DAYS. AS FOR LOW TEMPS...EVERY NIGHT IS EXPECTED TO BE FAIRLY SIMILAR AND RATHER UNIFORM ACROSS THE CWA...EITHER IN THE LOW OR MID 60S. STARTING OFF WEDNESDAY EVENING/NIGHT...GAVE A BEST-STAB AT TWO 6-HOUR POP BLOCKS HEAVILY BASED ON MET/MAV GUIDANCE BLEND...WITH THE EVENING PERIOD FEATURING 20S-40S...AND THE LATE NIGHT PERIOD RANGING FROM ONLY 20S FAR WEST TO 50S IN EASTERN-MOST NEB ZONES. IN OTHER WORDS...THERE IS A DECENT CHANCE THAT PARTS OF THE CWA WILL SEE RAIN...BUT CONFIDENCE IN TIMING/PLACEMENT PRECLUDES LIKELY POPS ANYWHERE YET. ON THE LARGE-SCALE ALOFT...LEGITIMATE NORTHWEST-FLOW IS IN PLACE OVER THE CENTRAL PLAINS...BETWEEN A RIDGE AXIS EXTENDING NORTHWARD ACROSS THE ROCKIES FROM NORTHERN MEXICO INTO SOUTHWEST CANADA...AND A BROAD TROUGH ANCHORED OVER SOUTHEAST CANADA/THE NORTHEAST CONUS. ON A MORE LOCAL/REGIONAL LEVEL...THE CWA IS PROGGED TO REMAIN UNDER/NEAR THE MAIN TRACK OF LOW-AMPLITUDE SHORTWAVE TROUGHS RIPPLING THROUGH THE NORTHWEST FLOW. STARTING OFF RIGHT AWAY WED EVENING AT 00Z/7PM...ITS EXPECTED THAT AT LEAST A SMALL PART OF THE CWA SHOULD BE SEEING ACTIVITY PERSISTING FROM THE LATE AFTERNOON HOURS...ALTHOUGH MODEL QPF/REFLECTIVITY FIELDS VARY CONSIDERABLY ON THE MOST FAVORED AREA. AS THE NIGHT WEARS ON...THERE IS A DECENT SIGNAL FOR WARM AIR ADVECTION/MOISTURE TRANSPORT IN THE 850-700 MILLIBAR LAYER...WITHIN THE AXIS OF A MODEST 20+KT SOUTHWESTERLY LOW LEVEL JET. PER THE 12Z/18Z NAM AND LAST FEW SREF RUNS...THIS WOULD FAVOR EASTERN ZONES FOR THE HIGHEST LATE NIGHT POPS...WHILE THE ECWMF/GFS WOULD MORE-SO FAVOR CENTRAL/SOUTHWEST ZONES. AS FOR THUNDERSTORM INTENSITY...ALTHOUGH NOT EXPECTING A WIDESPREAD NOCTURNAL SEVERE THREAT...CERTAINLY A FEW STRONG TO MARGINALLY SEVERE STORMS WITH MAINLY A HAIL/LOCALLY HEAVY RAIN THREAT CANNOT BE RULED OUT GIVEN MUCAPE INCREASING TO AT LEAST 500-1000 J/KG IN THE PRESENCE OF AROUND 25KT OF DEEP LAYER SHEAR. THURSDAY/THURSDAY NIGHT...THIS 24 HOURS WOULD APPEAR TO CONTAIN THE OVERALL-HIGHEST THREAT OF SEVERE STORMS DURING THE NEXT SEVERAL DAYS...ALTHOUGH THE JURY IS STILL OUT ON WHETHER IT WOULD BE MORE LOCALIZED OR MORE WIDESPREAD. CERTAINLY WOULD NOT BE SURPRISED TO SEE THE UPCOMING SPC DAY 2 OUTLOOK INTRODUCE A SLIGHT RISK FOR ALL/PART OF THE CWA...MAINLY FOR THE AFTERNOON/EVENING HOURS. IN THE BIG PICTURE...SEASONABLY STRONG/SHARP NORTHWEST FLOW STRENGTHENS AB IT...AS MODELS ARE IN DECENT AGREEMENT IN DRIVING A BIT STRONGER/ORGANIZED SHORTWAVE TROUGH SOUTHWARD OUT OF WESTERN SD ACROSS THE HEART OF CENTRAL NEB/KS. FOR THE MORNING HOURS...KEPT POPS AT SLIGHT 20S EXCEPT 30S IN THE EAST WHERE SEEMINGLY THE BEST CHANCE OF LINGERING OVERNIGHT CONVECTION WOULD BE. THEN HAVE 30 POPS NEARLY ALL AREAS DURING THE AFTERNOON TO ACCOUNT FOR THUNDERSTORM REDEVELOPMENT AND/OR RE-INTENSIFICATION...ASSUMING OF COURSE THAT SUFFICIENT HEATING CAN TAKE PLACE. ITS STILL TOO SOON TO TELL THOUGH WHETHER POTENTIALLY VIGOROUS AFTERNOON ACTIVITY MAINLY DEVELOPS LOCALLY OR MOVES IN FROM THE NORTHWEST. AT ANY RATE...THE 18Z NAM DEPICTS A FAIRLY POTENT NORTHWEST FLOW SEVERE ENVIRONMENT WITH MIXED LAYER CAPE 2000+ J/KG IN THE PRESENCE OF DECENT 30-40 KNOT DEEP LAYER SHEAR...MAKING A FEW SUPERCELLS A POSSIBILITY IF THE MESOSCALE FEATURES COME TOGETHER. FOR THURSDAY EVENING/NIGHT...KEPT 30-50 POPS GOING AREA-WIDE...HIGHEST IN THE FAR SOUTH. NOT ACCOUNTING FOR POSSIBLE CONVECTIVE EFFECTS...BREEZES DURING THE DAY THURSDAY ARE EXPECTED TO AVERAGE AROUND 10 MPH FROM THE SOUTH. FRIDAY/FRIDAY NIGHT...THE LATEST NAM/GFS ARE IN GOOD AGREEMENT AMPLIFYING THE WESTERN CONUS RIDGE EASTWARD OVER THE CENTRAL PLAINS...RESULTING IN MODEST HEIGHT RISES AND NEARLY DUE-NORTHERLY FLOW ALOFT. THIS SHOULD RESULT IN A LESS-FAVORABLE ENVIRONMENT FOR THUNDERSTORM DEVELOPMENT. HOWEVER...KEPT THE MAJORITY OF THE CWA WITH SLIGHT POPS DURING THE DAYTIME HOURS MAINLY TO ACCOUNT FOR POSSIBLE DIURNAL-HEATING INDUCED CONVECTION...BUT LEFT FRIDAY NIGHT DRY PER PREVIOUS FORECAST. SATURDAY THROUGH SUNDAY...KEPT THE DRY FORECAST GOING CWA- WIDE...AS SEEMINGLY-BENIGN NORTHERLY FLOW REMAINS IN PLACE ALOFT TO THE EAST OF THE ROCKIES-CENTERED RIDGE AXIS. BOTH THE ECWMF/GFS KEEP THE MAIN BRANCHES OF STRONGER FLOW ALOFT WELL NORTH NEAR THE CANADIAN BORDER...AND ALSO IN THE SOUTHEAST STATES...WITH THE CWA ALSO STAYING SAFELY NORTHWEST OF A STALLED...POSSIBLY RETROGRADING CLOSED MID LEVEL LOW OVER THE SOUTHERN MO/AR AREA ADVERTISED MORE SO BY THE ECMWF THAN THE GFS. NOT READY TO GUARANTEE A DRY WEEKEND YET...BUT AT LEAST FOR NOW POPS HAVE BEEN KEPT IN THE SILENT 5-10 RANGE. GIVEN THAT THE AREA HAS SEEN VERY LITTLE IN THE WAY OF NON- CONVECTIVE BREEZE LATELY...ITS WORTH NOTING THAT THE CURRENT SUNDAY FORECAST ACTUALLY HAS SUSTAINED SOUTHERLY SPEEDS UP AROUND 15 MPH/GUSTS AROUND 20 MPH. SUNDAY NIGHT THROUGH TUESDAY MARKS THE RETURN OF VARIOUS...LOW- CONFIDENCE THUNDERSTORM CHANCES OF THE 20-30 PERCENT VARIETY...THAT WILL UNDOUBTEDLY BE REFINED SEVERAL TIMES DURING THE NEXT SEVERAL DAYS. FROM A GENERAL...SYNOPTIC SCALE STANDPOINT...BOTH THE ECWMF/GFS BREAK DOWN THE RIDGE-DOMINATED PATTERN FROM THE WEEKEND AND GRADUALLY BRINGS A QUASI-ZONAL PATTERN AS ONE OR TWO FAIRLY LOW-AMPLITUDE SHORTWAVE TROUGHS OF NOTE WORK INTO THE CENTRAL PLAINS FROM THE WEST. THIS SHOULD SUPPORT A CONTINUED SURFACE PATTERN OF LIGHT BUT NOTICEABLY SOUTHERLY BREEZES. && .AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1245 PM CDT TUE AUG 13 2013 THE RAIN IS ON THE WAY OUT OF KGRI AND EXPECT VISIBILITY AND CEILINGS WILL IMPROVE INTO VFR RANGE BETWEEN 18Z AND 19Z. DRY WEATHER IS LIKELY THROUGH THE REMAINDER OF THE TAF PERIOD WITH LIGHT WINDS. THE WIND DIRECTION WILL GENERALLY BE VARIABLE THROUGH TONIGHT AND THEN SHOULD BECOME PREDOMINATELY SOUTHERLY BY EARLY TOMORROW MORNING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...WESELY LONG TERM...PFANNKUCH AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1241 AM CDT TUE AUG 13 2013 .UPDATE... ISSUED AT 1241 AM CDT TUE AUG 13 2013 LOW TEMPS WERE RAISED 2-3F WITH THIS ESTF UPDATE BASED ON CURRENT AND EXPECTED CLOUD COVER. ALSO REMOVED POPS FOR THE NEXT 3 HRS. WE ARE NOTING SHWRS WITH OCCASIONAL THUNDER DEVELOPING OVER SRN SD DOWN INTO THE SANDHILLS. PER THE PREVIOUS SHIFTS EXPECTATION... THESE SHWRS SHOULD ARRIVE INTO S-CNTRL NEB BEFORE DAWN AND COULD COMPLICATE TOMORROW`S FCST. CLOUDS WERE ALSO INCREASED THRU DAYBREAK. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 414 PM CDT MON AUG 12 2013 THE MAIN ISSUES DURING THE NEXT 24 HOURS INCLUDE FICKLE THUNDERSTORM CHANCES...ALONG WITH WHETHER OR NOT FOG TONIGHT MIGHT END UP BEING IMPACTFUL IN SOME SPOTS. 20Z OBJECTIVE SURFACE ANALYSIS SHOWS A WEAK COLD FRONT STRETCHED ACROSS KS FROM SOUTHWEST-NORTHEAST...WHILE TO THE NORTH OF THIS BOUNDARY...THE MAJORITY OF THE CWA IS EXPERIENCING LIGHT BREEZES RANGING FROM NEAR-CALM TO NO MORE THAN 5-10 MPH FROM THE EAST- NORTHEAST UNDER THE INFLUENCE OF BROAD HIGH PRESSURE EXTENDING WELL SOUTHWARD FROM CANADA. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA SHOWS GENERALLY WEST-NORTHWEST FLOW ALOFT OVER THE CENTRAL PLAINS...MORE WESTERLY UP AROUND 300 MILLIBARS..AND MORE NORTHERLY FARTHER DOWN IN THE MID LEVELS 500/700 MILLIBARS. THIS FLOW REGIME REMAINS ESTABLISHED BETWEEN A LARGE SCALE TROUGH OVER THE GREAT LAKES/SOUTHEAST CANADA AREA...AND A RIDGE EXTENDING NORTH-NORTHWEST INTO THE ROCKIES OUT OF THE TX/NORTHERN MEXICO AREA. IN TERMS OF THE REGIONAL SCALE...THE MAIN LOW AMPLITUDE DISTURBANCE OF INTEREST HAS PASSED ONTO THE EAST INTO MO...ALTHOUGH SMALL RIBBONS OF CHANNELED VORTICITY ARE EVIDENT EXTENDING BACK WEST-NORTHWEST ACROSS THE SOUTHERN CWA TOWARD THE WY/NE/CO BORDER AREA PER LATEST OBJECTIVE MESO-ANALYSIS. DESPITE WHAT VARIOUS MODELS WERE EARLIER-SHOWING...THE CWA HAS REMAINED DRY ALL DAY IN THE WAKE OF THE EXTENSIVE CONVECTION SUNDAY EVENING/EARLY THIS MORNING. VISIBLE SATELLITE REVEALS ONLY A SCATTERED TO LOCALLY BROKEN FAIR WEATHER CUMULUS FIELD MAINLY IN THE FAR NORTHERN/EASTERN/SOUTHERN COUNTIES...AND HIGH TEMPERATURES ARE ON TRACK TO TOP OUT 82-85 NEARLY ALL AREAS. FOR LATE THIS AFTERNOON INTO THIS EVENING...MODELS CONTINUE TO STRUGGLE WITH THEIR INDIVIDUAL QPF FIELDS...AS SOME APPEAR TO THINK THAT CONVECTION WILL BREACH A WEAK CAP LOCALLY. LEANING TOWARD THE HIGHER-RES SOLUTIONS OF THE HRRR AND 4KM WRF NMM/ARW...IT APPEARS RATHER UNLIKELY THAT ANYTHING WILL POP IN THE NEXT 3-6 HOURS ESPECIALLY ACROSS THE CENTRAL/EASTERN CWA DUE TO LACK OF FORCING AND LACK OF LOW-LEVEL CONVERGENCE...AS THE WEAK CAP SHOULD HOLD DESPITE THE PRESENCE OF 1000-1500 J/KG 0-1KM MIXED LAYER CAPE PER LATEST RUC ANALYSIS. AS A RESULT...THROUGH MIDNIGHT HAVE CONFINED SLIGHT POPS TO MAINLY THE WESTERN 1/4 TO 1/3 OF THE CWA...MAINLY TO ACCOUNT FOR THE SMALL POSSIBILITY THAT STORMS CURRENTLY DEVELOPING IN WESTERN NEB...AND MAYBE EVENTUALLY IN NORTHWEST KS AS WELL...MIGHT SLIP EASTWARD INTO THE CWA. GIVEN THE CONTINUED WEAK DEEP LAYER SHEAR REGIME ONLY AROUND 20KT...AND INSTABILITY FADING WITH TIME TONIGHT...THINK THE PROBABILITY OF STRONG THUNDERSTORMS...LET ALONE SEVERE...IS QUITE LOW. AFTER MIDNIGHT...UNCERTAINTY CONTINUES TO GROW...BUT WITH BOTH THE LATEST HRRR AND 18Z NAM ADVERTISING SOME CONVECTION FLARING UP MAINLY JUST NORTHWEST OF THE CWA LIKELY IN RESPONSE TO SOME SUBTLE MID LEVEL THETA-E ADVECTION...AND OTHER MODELS SHOWING CONVECTION LURKING IN OR NEAR KS ZONES...WENT AHEAD AND EXPANDED 20-30 POPS TO INCLUDE ALL BUT A HANDFUL OF SOUTHEASTERN COUNTIES JUST IN CASE. THE OTHER POTENTIAL ISSUE TONIGHT IS FOG. WHILE MET/MAV GUIDANCE IS SUGGESTING ONLY SOME LIGHT FOG...THE 15Z SREF SUGGESTS PERHAPS AN ENHANCED RISK OF VISIBILITY RESTRICTIONS BELOW 1 MILE ESPECIALLY ACROSS THE SOUTHWEST 1/3 OF THE CWA LATE TONIGHT. CERTAINLY THE VERY LIGHT EASTERLY FLOW REGIME AND RECENT RAINFALL COULD HELP THE CAUSE OF FOG FORMATION...BUT GIVEN THAT FOG DID NOT BECOME TOO MUCH OF AN ISSUE LAST NIGHT IN THE WAKE OF DEPARTING CONVECTION WITH A SIMILAR WIND REGIME...DECIDED TO ONLY INTRODUCE A PATCHY FOG MENTION CWA-WIDE FOR NOW LATE TONIGHT...AND DEFER TO NEXT FEW SHIFTS TO MONITOR THE SITUATION AND RAMP UP FOG POTENTIAL IF NECESSARY. TURNING TO THE TUESDAY DAYTIME HOURS...THE QUESTIONS JUST CONTINUE TO ARISE. TAKING VARIOUS MODEL QPF FIELDS AT FACE VALUE...THERE COULD BE QUITE A BIT OF ONGOING CONVECTION DURING THE DAY...ESPECIALLY ACROSS THE WESTERN HALF OF THE CWA...POSSIBLY AS A CONTINUATION OF OVERNIGHT ACTIVITY MOVING IN...OR LOCAL DEVELOPMENT RAMPING UP WITH DAYTIME HEATING...AS THE THERMODYNAMIC STRUCTURE OF THE ATMOSPHERE SHOULD REMAIN SIMILAR TO TODAY WITH WEAK CAPPING IN THE PRESENCE OF ROUGHLY 1000 J/KG OF CAPE. THE MILLION DOLLAR QUESTION IS WHETHER NOT FORCING WILL BE STRONG ENOUGH TO REALIZE THE POTENTIALLY WIDESPREAD CONVECTION ADVERTISED BY SOME MODELS...OR WHETHER MODELS ARE OVER-DOING QPF AS SEVERAL DID FOR TODAY. THERE SHOULD AT LEAST BE A FEW SUBTLE SHORTWAVE TROUGHS PASSING THROUGH THE REGION PER MODEL VORTICITY FIELDS...PRIMARILY PASSING ACROSS THE SOUTHWEST 1/2 OF THE CWA AND POINT SOUTH. FOR NOW...DECIDED TO MAKE LITTLE CHANGE TO PREVIOUS FORECAST WHICH ALREADY HAD POPS LOW AT NO MORE THAN 20-30 PERCENT...WITH THESE CHANCES COVERING MOST OF THE CWA IN THE MORNING...AND THE ENTIRE AREA IN THE AFTERNOON. IF FORCING IS IN FACT ENOUGH TO GENERATE WIDESPREAD CONVECTION...THEN NEXT SHIFT MAY HAVE TO RAISE POPS NOTICEABLY ESPECIALLY IN WESTERN AREAS...BUT AFTER SEEING HOW TODAY ENDED UP BONE-DRY THROUGH LATE AFTERNOON...THINK IT WOULD BE UNWISE TO GET CARRIED AWAY WITH RAIN CHANCES EVEN 12-24 HOURS OUT. AGAIN...NOT EXPECTING ANY SEVERE STORMS...BUT A LOCALIZED STRONG STORM PROBABLY NOT OUT OF THE QUESTION. OBVIOUSLY HIGH TEMPERATURES WILL BE HIGHLY DEPENDENT ON THE COVERAGE...OR LACK THEREOF...OF DAYTIME CONVECTION...SO THERE IS SOME UNCERTAINTY HERE TOO. GIVEN A SIMILAR LOW-LEVEL TEMP REGIME...BLENDED THE COOLER PREVIOUS FORECAST FOR TOMORROW WITH READINGS SIMILAR TO THOSE OBSERVED TODAY...WHICH RESULTS IN A SLIGHT INCREASE TO PREVIOUS HIGHS AND NOW CALLING FOR 79-82 MOST AREAS. BREEZES DURING THE DAY SHOULD AVERAGE ONLY 5-10 MPH FROM THE EAST ASSUMING CONVECTIVE OUTFLOW DOESN/T GET TOO INVOLVED. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 414 PM CDT MON AUG 12 2013 HE COOLER THAN NORMAL TREND WILL LIKELY CONTINUE THROUGH AT LEAST SATURDAY...WITH PERHAPS A RETURN OF NEAR NORMAL HIGHS BY SUNDAY AND MONDAY. WEAK SHORT WAVES WILL TRACK ACROSS OUR FORECAST AREA WITHIN THE PERSISTENT UPPER LEVEL NORTHWESTERLY FLOW REGIME. CONSEQUENTLY...ISOLATED TO SCATTERED THUNDERSTORMS WILL REMAIN POSSIBLE ACROSS AT LEAST PORTIONS OF OUR FORECAST AREA OFF AND ON AGAIN THROUGH MUCH OF THE PERIOD. TUESDAY NIGHT THROUGH WEDNESDAY...A DECENT 500 MB VORT MAX/SHORT WAVE WILL TRACK SOUTHEAST ACROSS THE HIGH PLAINS BRINGING A CHANCE OF THUNDERSTORMS PRIMARILY TO AREAS WEST OF OUR FORECAST AREA. HOWEVER...THERE IS GENERALLY A SLIGHT CHANCE THAT A FEW OF THESE THUNDERSTORMS COULD TRACK INTO OUR WESTERN ZONES PRIMARILY WEST OF HWY 281. INSTABILITY AND SHEAR ARE BOTH WEAK AND THUS ANY THUNDERSTORMS THAT WORK INTO OUR AREA WILL LIKELY BE NON SEVERE. TEMPERATURES WILL BE COOL FOR THIS TIME OF YEAR WITH THE UPPER LEVEL JET STREAM TO OUR SOUTH. WEDNESDAY NIGHT THROUGH FRIDAY...THIS SHOULD BE OUR BEST CHANCE AT MORE WIDESPREAD THUNDERSTORM POTENTIAL ACROSS THE FORECAST AREA AS A TRAIN OF SUCCESSIVE SHORT WAVE TROUGHS WORK THEIR WAY ACROSS THE CENTRAL PLAINS. UPPER LEVEL SHEAR AND INSTABILITY WILL ALSO BE ON THE INCREASE ESPECIALLY THURSDAY AFTERNOON THROUGH FRIDAY...WHICH MAY RESULT IN A FEW STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. AT THIS POINT...IT DOES NOT APPEAR TO BE A WIDESPREAD SEVERE EVENT...BUT CAN NOT RULE OUT THE POSSIBILITY OF ISOLATED SEVERE STORMS. TEMPERATURES WILL REMAIN RELATIVELY COOL...UPPER 70S TO AROUND 80 DUE TO CLOUDS...POTENTIAL PRECIPITATION...AND MEAN MID AND UPPER LEVEL JET POSITION. SATURDAY AND SUNDAY...A BIT OF AN UPPER RIDGE IS PREDICTED TO WORK INTO OUR FORECAST AREA THAT IF IT VERIFIES WOULD RESULT IN DRY CONDITIONS THIS WEEKEND AND THEN WARMING TEMPERATURES TO NEAR NORMAL BY SUNDAY. SUNDAY NIGHT AND MONDAY...THE NEXT UPPER SHORT WAVE IS PROJECTED BY BOTH THE 12Z GFS AND 12Z ECMWF TO MOVE INTO THE CENTRAL PLAINS. THIS WILL RESULT IN AT LEAST SOME CHANCE OF THUNDERSTORMS...PARTICULARLY ACROSS OUR WEST...ALTHOUGH THESE CHANCES MAY EVENTUALLY NEED TO BE EXPANDED/RAISED SHOULD CURRENT FAVORABLE MODEL TRENDS CONTINUE. ALLBLEND GIVES US NEAR NORMAL TEMPERATURES...AND LIKELIHOOD IS THAT WE WILL LIKELY BE NO WARMER THAN NORMAL...AND WOULD NOT BE SURPRISED IF MONDAY HIGHS GET LOWERED SOME WITH FUTURE FORECAST UPDATES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1241 AM CDT TUE AUG 13 2013 REST OF TNGT: VFR THRU 10Z WITH OCCASIONAL CIGS AROUND 5K FT. THEN SOME MVFR FOG IS POSSIBLE 11Z-12Z. LIGHT E WINDS. TUE: VFR WITH SCT SHWRS AND POSSIBLE THUNDER. TIMING OF ANY PCPN IS UNCERTAIN GIVEN ITS SCT NATURE. SO IT`S BEEN HANDLED WITH VCSH FOR NOW. WATCH FOR POSSIBLE AMENDMENTS TO UPGRADE TO TSRA. ESE WINDS LESS THAN 10 KTS. TUE EVNG: VFR WITH SOME MISC DEBRIS CLOUDS AROUND 8K AND 25K FT. WINDS WILL BECOME LIGHT AND VARIABLE. CIG CONFIDENCE: MEDIUM VSBY CONFIDENCE: MEDIUM WIND CONFIDENCE: HIGH WX CONFIDENCE: MEDIUM && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...PFANNKUCH LONG TERM...WESELY AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
749 PM EDT WED AUG 14 2013 .SYNOPSIS... SCATTERED SHOWERS ASSOCIATED WITH AN UPPER TROUGH MOVING OVER THE REGION WILL SUBSIDE LATER THIS EVENING...WITH A MOSTLY CLEAR AND DRY NIGHT EXPECTED. A RIDGE OF HIGH PRESSURE WILL BUILD EAST INTO THE NORTHEAST THURSDAY AND FRIDAY WITH MAINLY DRY WEATHER...THOUGH A FEW ISOLATED SHOWERS ACROSS THE HIGHER TERRAIN WILL BE POSSIBLE. WARMER TEMPERATURES AND A PROLONGED PERIOD OF FAIR AND DRY CONDITIONS RETURNS TO THE NORTH COUNTRY THIS WEEKEND THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 716 PM EDT WEDNESDAY...INHERITED FORECAST REMAINS IN GOOD SHAPE THOUGH CONTINUED ISOLATED SHOWERS INTO THE MID EVENING HOURS BASED ON RADAR TRENDS. GENERAL IDEA THAT THESE SHOWERS SHOULD BEGIN TO DISSIPATE STILL LOOKS GOOD. HOWEVER...AN UPPER-LEVEL SHORTWAVE TROUGH OVER NORTHERN ONTARIO IS PRODUCING A THICK DECK OF LOW CLOUDS WHICH ARE DIVING SOUTHWARD FROM HUDSON BAY...WITH ITS SOUTHERN EXTENT TO ROUGHLY PETAWAWA ONTARIO PER IR SATELLITE IMAGERY. MOST RECENT SHORT- RANGE RH GUIDANCE SUCH AS THE 18Z NAM AND 21Z RAP ALL SHOW THESE CLOUDS APPROACHING THE INTERNATIONAL BORDER AROUND 05Z. IF TRENDS CONTINUE IT WOULD NECESSITATE SOME UPWARD ADJUSTMENTS TO SKY COVER AND LOW TEMPERATURES..BUT FOR NOW I WILL WAIT TO SEE HOW THESE TRENDS EVOLVE BEFORE MAKING THOSE CHANGES WITH THE NEXT UPDATE. OTHERWISE HAVE JUST MATCHED WITH CURRENT SFC OBSERVATIONAL DATA. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 334 PM EDT WEDNESDAY...FOR THE SHORT TERM PERIOD FROM THURSDAY THROUGH FRIDAY NIGHT...SURFACE HIGH PRESSURE CONTINUES TO BUILD INTO THE NORTHEAST AND MID-ATLANTIC STATES WHILE THE AFOREMENTIONED UPPER TROUGH SLOWLY SHIFTS NORTHEAST INTO THE GULF OF SAINT LAWRENCE. CONDITIONS ARE EXPECTED TO BE MAINLY DRY ACROSS THE REGION THROUGH THE PERIOD...BUT ADDITIONAL SHORTWAVE ENERGY ROUNDING THE BASE OF THE TROUGH GLANCING THE INTL BORDER THURSDAY AND FRIDAY AFTERNOONS MAY PROVIDE A FEW ISOLATED TERRAIN DRIVEN SHOWERS ACROSS NORTHERN VERMONT. OTHERWISE...GENERALLY MOSTLY CLEAR TO PARTLY CLOUDY SKIES ARE EXPECTED WITH TEMPS REMAINING ON THE COOL SIDE OF NORMAL WITH HIGHS IN THE UPPER 60S TO MID 70S...AND LOWS IN THE MID 40S TO LOWER 50S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 348 PM EDT WEDNESDAY...OVERALL TRANQUIL WEATHER EXPECTED THROUGHOUT THE LONG TERM WITH NOT MUCH CHANGE IN MODEL GUIDANCE. AT THE SFC...HIGH PRESSURE WILL DOMINATE THE NORTHEAST WITH FLAT ZONAL FLOW ACROSS SOUTHERN CANADA. SOME DIURNAL CLOUDS MAINLY OVER THE MTNS EXPECTED THROUGHOUT THE PERIOD AND GRADUAL WARMING TREND AS THE SFC HIGH ANCHORS TO OUR EAST...ALLOWING FOR SLGT S/SW FLOW OVER THE NORTH COUNTRY. BEST CHANCE FOR SOME PRECIPITATION WILL BE TUESDAY AS AN UPPER LEVEL TROUGH MOVES ACROSS SRN QUEBEC. MODELS DIVERGE ON TRACK AND EVOLUTION OF THIS UPPER TROUGH...SO CONFIDENCE ON CHANCES FOR PRECIP LOW THROUGH THE END OF THE PERIOD. TEMPERATURES DURING THE DAY WILL REACH THE 70S-M80S...AND DIP INTO THE M40S-L60S OVERNIGHT. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THROUGH 18Z THURSDAY...MAINLY VFR COND EXPECTED THRU FORECAST PERIOD. SCT-BKN050-120 FOR CEILINGS W/ VCSH THRU 02Z THURS...AND AGAIN AFT 18Z THURS. SLK/MPV WILL SEE IFR TO VLIFR COND FROM 05Z-13Z DUE TO FG DEVELOPMENT AS WINDS ABATE. WINDS WILL VARY MAINLY WSW-WNW 5-15KTS. LGT/VAR AT TIMES THOUGH AFT 05Z. OUTLOOK 18Z THURSDAY THROUGH MONDAY...GENERALLY VFR CONDITIONS UNDER HIGH PRESSURE WITH PERIODS OF VLIFR FOG/MIST EACH EVENING AT KMPV AND KSLK. && .MARINE... AS OF 330 PM EDT WEDNESDAY...A LAKE WIND ADVISORY REMAINS IN EFFECT THROUGH TONIGHT. GENERALLY WEST WINDS FROM 15 TO 25 KNOTS CAN BE EXPECTED THIS EVENING AND OVERNIGHT. WINDS MAY BE VARIABLY NORTHWEST THIS EVENING AND SOUTHWEST AFTER MIDNIGHT. CHOPPY WAVES OF 1 TO 3 FEET CAN BE EXPECTED...ESPECIALLY ACROSS THE EASTERN HALF OF THE LAKE. A FEW SCATTERED RAIN SHOWERS THIS EVENING WILL TAPER OFF AND END BY SUNSET. && .EQUIPMENT... AS OF 435 AM EDT WEDNESDAY...NOAA WEATHER RADIO STATION WXM 44... BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...LAHIFF NEAR TERM...LAHIFF/LOCONTO SHORT TERM...LAHIFF LONG TERM...KGM AVIATION...KGM/JN MARINE...MUCCILLI EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
716 PM EDT WED AUG 14 2013 .SYNOPSIS... SCATTERED SHOWERS ASSOCIATED WITH AN UPPER TROUGH MOVING OVER THE REGION WILL SUBSIDE LATER THIS EVENING...WITH A MOSTLY CLEAR AND DRY NIGHT EXPECTED. A RIDGE OF HIGH PRESSURE WILL BUILD EAST INTO THE NORTHEAST THURSDAY AND FRIDAY WITH MAINLY DRY WEATHER...THOUGH A FEW ISOLATED SHOWERS ACROSS THE HIGHER TERRAIN WILL BE POSSIBLE. WARMER TEMPERATURES AND A PROLONGED PERIOD OF FAIR AND DRY CONDITIONS RETURNS TO THE NORTH COUNTRY THIS WEEKEND THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 716 PM EDT WEDNESDAY...INHERITED FORECAST REMAINS IN GOOD SHAPE THOUGH CONTINUED ISOLATED SHOWERS INTO THE MID EVENING HOURS BASED ON RADAR TRENDS. GENERAL IDEA THAT THESE SHOWERS SHOULD BEGIN TO DISSIPATE STILL LOOKS GOOD. HOWEVER...AN UPPER-LEVEL SHORTWAVE TROUGH OVER NORTHERN ONTARIO IS PRODUCING A THICK DECK OF LOW CLOUDS WHICH ARE DIVING SOUTHWARD FROM HUDSON BAY...WITH ITS SOUTHERN EXTENT TO ROUGHLY PETAWAWA ONTARIO PER IR SATELLITE IMAGERY. MOST RECENT SHORT- RANGE RH GUIDANCE SUCH AS THE 18Z NAM AND 21Z RAP ALL SHOW THESE CLOUDS APPROACHING THE INTERNATIONAL BORDER AROUND 05Z. IF TRENDS CONTINUE IT WOULD NECESSITATE SOME UPWARD ADJUSTMENTS TO SKY COVER AND LOW TEMPERATURES..BUT FOR NOW I WILL WAIT TO SEE HOW THESE TRENDS EVOLVE BEFORE MAKING THOSE CHANGES WITH THE NEXT UPDATE. OTHERWISE HAVE JUST MATCHED WITH CURRENT SFC OBSERVATIONAL DATA. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 334 PM EDT WEDNESDAY...FOR THE SHORT TERM PERIOD FROM THURSDAY THROUGH FRIDAY NIGHT...SURFACE HIGH PRESSURE CONTINUES TO BUILD INTO THE NORTHEAST AND MID-ATLANTIC STATES WHILE THE AFOREMENTIONED UPPER TROUGH SLOWLY SHIFTS NORTHEAST INTO THE GULF OF SAINT LAWRENCE. CONDITIONS ARE EXPECTED TO BE MAINLY DRY ACROSS THE REGION THROUGH THE PERIOD...BUT ADDITIONAL SHORTWAVE ENERGY ROUNDING THE BASE OF THE TROUGH GLANCING THE INTL BORDER THURSDAY AND FRIDAY AFTERNOONS MAY PROVIDE A FEW ISOLATED TERRAIN DRIVEN SHOWERS ACROSS NORTHERN VERMONT. OTHERWISE...GENERALLY MOSTLY CLEAR TO PARTLY CLOUDY SKIES ARE EXPECTED WITH TEMPS REMAINING ON THE COOL SIDE OF NORMAL WITH HIGHS IN THE UPPER 60S TO MID 70S...AND LOWS IN THE MID 40S TO LOWER 50S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 348 PM EDT WEDNESDAY...OVERALL TRANQUIL WEATHER EXPECTED THROUGHOUT THE LONG TERM WITH NOT MUCH CHANGE IN MODEL GUIDANCE. AT THE SFC...HIGH PRESSURE WILL DOMINATE THE NORTHEAST WITH FLAT ZONAL FLOW ACROSS SOUTHERN CANADA. SOME DIURNAL CLOUDS MAINLY OVER THE MTNS EXPECTED THROUGHOUT THE PERIOD AND GRADUAL WARMING TREND AS THE SFC HIGH ANCHORS TO OUR EAST...ALLOWING FOR SLGT S/SW FLOW OVER THE NORTH COUNTRY. BEST CHANCE FOR SOME PRECIPITATION WILL BE TUESDAY AS AN UPPER LEVEL TROUGH MOVES ACROSS SRN QUEBEC. MODELS DIVERGE ON TRACK AND EVOLUTION OF THIS UPPER TROUGH...SO CONFIDENCE ON CHANCES FOR PRECIP LOW THROUGH THE END OF THE PERIOD. TEMPERATURES DURING THE DAY WILL REACH THE 70S-M80S...AND DIP INTO THE M40S-L60S OVERNIGHT. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... THROUGH 18Z THURSDAY...VFR WITH SCT SHOWERS WILL CONTINUE TO AFFECT THE NORTH COUNTRY PRODUCING PERIODS OF MVFR/IFR THIS AFTN. SHOWERS MOST NUMEROUS OVER NRN NY AND NRN HALF OF VT. WITH LOSS OF DAYTIME HEATING...GOING INTO THE EVENING HRS...SHOWERS WILL DIMINISH AS WILL ACCOMPANYING CLOUD COVER. EXPECT GENERALLY CLEARING SKIES OVERNIGHT...WITH MOISTURE FROM TODAY`S SHOWERS TO PRODUCE SOME MVFR/IFR BR/FG AFTER MIDNIGHT...MAINLY AT KMPV/KSLK AND KPBG. NW-N WINDS...OCCASIONALLY GUSTY THIS AFTN WILL DIMINISH TO LIGHT TO CALM CONDITIONS AFTER SUNSET. AFTER 12Z...TAF SITES WILL RECOVER TO VFR WITH INCREASING WINDS OUT OF THE S-SW AT 7-14KTS. MID LVL CLOUDS WILL ALSO INCREASE...WITH SOME DIURNAL LOW CLOUDS DEVELOPING IN THE LATE MORNING. OUTLOOK 18Z THURSDAY THROUGH MONDAY...GENERALLY VFR CONDITIONS UNDER HIGH PRESSURE WITH PERIODS OF VLIFR FOG/MIST EACH EVENING AT KMPV AND KSLK. && .MARINE... AS OF 330 PM EDT WEDNESDAY...A LAKE WIND ADVISORY REMAINS IN EFFECT THROUGH TONIGHT. GENERALLY WEST WINDS FROM 15 TO 25 KNOTS CAN BE EXPECTED THIS EVENING AND OVERNIGHT. WINDS MAY BE VARIABLY NORTHWEST THIS EVENING AND SOUTHWEST AFTER MIDNIGHT. CHOPPY WAVES OF 1 TO 3 FEET CAN BE EXPECTED...ESPECIALLY ACROSS THE EASTERN HALF OF THE LAKE. A FEW SCATTERED RAIN SHOWERS THIS EVENING WILL TAPER OFF AND END BY SUNSET. && .EQUIPMENT... AS OF 435 AM EDT WEDNESDAY...NOAA WEATHER RADIO STATION WXM 44... BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...LAHIFF NEAR TERM...LAHIFF/LOCONTO SHORT TERM...LAHIFF LONG TERM...KGM AVIATION...KGM/NEILES MARINE...MUCCILLI EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
150 AM EDT TUE AUG 13 2013 .SYNOPSIS... A COLD FRONT WILL APPROACH THE AREA TONIGHT AND PASS THROUGH THE REGION ON TUESDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. FAIR AND COOLER WEATHER WILL FOLLOW THE FRONT...WITH SLOWLY MODERATING TEMPERATURES INTO LATE WEEK. && .NEAR TERM /THROUGH TODAY/... 900 PM EDT UPDATE... ISOLATED LIGHT RAIN SHOWERS HAS DEVELOPED ACROSS THE REGION TONIGHT WHERE WAA AND THETA-E ADVECTION IS TAKING PLACE AHEAD OF AN APPROACHING UPPR LOW. VORT MAXES ARE BEING EJECTED FROM THE BASE OF THE TROUGH AND ARE MOVING WITHIN THE CYCLONIC FLOW OVER THE REGION...THUS EXPECT THESE SHOWERS TO CONTINUE AHEAD OF THE FROPA. AS THE WAA CONTINUES OVERNIGHT...EXPECT SHOWERS TO BECOME MORE SCATTERED LIKE IN NATURE. SKY COVERAGE HAS INCREASED OVER THE REGION THUS DO NOT BELIEVE THAT TEMPS WILL FALL MUCH FURTHER TONIGHT AS DENSE COVERAGE WILL INHIBIT HEAT LOSS. PREVIOUS FORECAST HOLDS GOOD AS FROPA IS EXPECTED TO MOVE THROUGH TUESDAY MORNING. PREVIOUS FORECAST... BATCH OF -SHRA OVER SW NY HAVING A TUFF TIME MAKING EWD PROGRESS INTO CNTRL NY...BUT A FEW -SHRA WILL PRBLY WORK INTO THE SRN TIER AND NE PA LATER THIS AFTN AND EVNG. BETTER CHCS FOR SHRA/TSRA WILL COME LATER TNGT THROUGH MIDDAY TUESDAY AS A COLD FRONT PASSES THE RGN. NAM HAS CDFNT JUST ENTERING THE FINGER LAKES AND WRN SRN TIER BY 12Z...MOVG SEWD AND PASSING AVP ARND 19Z...AND SHOWS A WEAK WAVE OF LOW PRES TRACKING ENEWD ALONG THE FNT WITH A PSN NEAR BGM BY 15Z. GFS IS A FEW HRS SLOWER THAN THE NAM. NAM SHOWS BEST AXIS OF QPF JUST N OF A LOW TRACKING ENEWD ALONG THE FNT...FROM THE CNTRL SRN TIER AND SRN FINGER LAKES INTO THE WRN MOHAWK VLY...WITH MAX QPF OF 1 TO 1.5 INCHES. THIS LOW IS NOT EVIDENT IN THE OTHER MDLS. HOWEVER...BOTH THE NAM/GFS SHOW PRE- FNTL PRECIPITABLE WATER RISING TO NEAR 1.5 INCHES. SUGGESTIONS OF STRENGTHENING UPR LVL DVRGNC IN RR QUAD OF AN UPR LVL JET TMRW. SO LOCALLY HEAVY RAINS ARE A POSSIBILITY AS THIS SYSTEM WORKS THROUGH. GREATEST CAPES ON TUE WILL BE OVER NE PA BY MIDDAY PRBLY MAXING OUT IN THE 500-750 J/KG RNG. SPC HAS SLGT RISK AREAS S AND E OF THE FCST AREA AND LOOKS GOOD. HOWEVER...WE`LL HAVE TO MONITOR FOR PSBLTY OF A FEW STRONG STORMS THERE ARND MIDDAY. CONDITIONS SHOULD BE IMPROVING ACROSS MUCH OF CNTRL NY IN THE AFTN...SPCLY OVER THE FINGER LAKES AND CNTRL SRN TIER. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... POTENT UPR LVL TROF...WHICH REMAINS WELL WEST OF THE INITIAL CDFNT...MOVS INTO WRN/CNTRL NY TMRW EVNG...ACCOMPANIED BY A WEAK 2NDRY SFC TROF WHICH IS FCST TO BE OVER LOWER LAKE ONTARIO BY 00Z WED. THESE FEATURES...IN COMBINATION WITH LAKE INFLUENCES SUGGESTS SCT -SHRA ACRS PORTIONS OF CNTRL NY TMRW EVNG IN NNWLY FLOW...ACTIVITY WHICH SHOULD DSPT LATE AT NGT AS MORE STABLE AND DRIER AIR WORKS IN. NAM/GFS LOW LVL RH FIELDS AND FCST SKEW-T`S SUGGESTS PTNL FOR LOW CLDS/STRATUS IN THIS COOLER NNW FLOW LATER TUE NGT INTO EARLY WED MRNG. PROFILES ALSO SHOW THE LIKELIHOOD OF DIURNALLY ENHANCED SCT-BKN CU OR STRATO-CU BOTH WED AND THU AFTN. TEMPS WILL BE ON THE COOL SIDE WED...MODERATING TO MORE SEASONABLE LVLS BY THU AFTN. CAN XPCT BREEZY CONDITIONS ON WED AS THE GTLAKES HIGH BUILDS IN. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... 1 PM MON UPDATE... ON THE LARGE-SCALE...THE TWO MAIN FIXTURES THIS PD WILL BE A STRENGTHENING WRN ATLANTIC UPR RIDGE...AND A WRN CONUS UPR RIDGE AXIS. IN BETWEEN THE TWO...A WEAKNESS IN THE HGT FIELDS LOOKS TO EXIST...WITH A FLAT MEAN TROUGH AXIS IN PLACE FROM THE TN VLY SWD TO THE GULF STATES. THE PRIMARY INFLUENCING SYSTEM FOR NY/PA DURG THIS TIME FRAME SHOULD BE THE WRN ATLANTIC UPR RIDGE...WITH A STG "BERMUDA HIGH" TYPE SFC ANTICYCLONE...EXTENDING FROM THE WRN ATLANTIC...BACK OVER THE ERN STATES. THIS SYNOPTIC PATN SEEMS FAVORABLE FOR A PROLONGED STRETCH OF DRY WX ACRS OUR FA...ALG WITH SLOWLY WARMING TEMPS OVER TIME. THE LATEST GFS/EC/WPC PROGS AGREE THAT THIS WILL INDEED BE THE CASE. FROM THIS EARLY VANTAGE PT...IT APPEARS THAT THE FIRST REAL CHC FOR ANY PCPN WON`T BE TIL SOMETIME EARLY NEXT WEEK (MON OR PERHAPS BEYOND)...WHEN SOME GULF MOISTURE ATTEMPTS TO PUSH NWD. EVEN AT THAT...WE`RE ONLY ADVERTISING SCHC-CHC POPS ATTM FROM LATE SUN NGT INTO NEXT MON. TEMPS WILL BE FAIRLY SEASONABLE MUCH OF THE PD...WITH HIGHS STARTING OFF IN THE 70S THU...GRADUALLY MODERATING INTO THE LWR- MIDDLE 80S BY LTR IN THE WEEKEND/NEXT WEEK. PREV DISC... 230 AM MON UPDATE... NO CHANGE FROM PREVIOUS FCST AS STRONG HIGH PRESSURE WILL ENSURE COOL AND FAIR WX THROUGH THE BULK OF THE PERIOD. SOME HINTS AT INCREASING MOISTURE TOWARDS NEXT WEEKEND WITH SHWRS/STORMS POSSIBLE BY SUN NGT/MON AS UPPER LOW BEGINS LIFTING NORTH FROM THE OHIO/TENN VLYS AND SFC HIGH PRESSURE BREAKS DOWN OVER NEW ENGLAND. WITH MAX JET ENERGY EXPECTED TO REMAIN SOUTH OF THE REGION...BETTER CHANCES FOR SHWRS/STORMS WILL EXIST FROM THE CENTRAL MID-ATLANTIC SOUTH. TEMPS SHOULD BEGIN MODERATING TOWARDS THE END OF THE WEEK WITH UPPER 70S TO NEAR 80 POSSIBLE BY SATURDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... 06Z UPDATE... AN AREA OF RAIN WITH EMBEDDED THUNDER CONTINUES TO MARCH ACROSS WESTERN NY AHEAD OF A COLD FRONT. EXPECT RAIN TO ARRIVE AT ALL TERMINALS BETWEEN 07Z AND 11Z. BASED ON OBS TO OUR WEST AND A MOISTURE LADEN ATMOSPHERE...IFR VSBYS ARE LIKELY FOR A 3 TO 4 HOUR PERIOD THIS MORNING DUE TO MODERATE/HEAVY RAIN. INCLUDED A TEMPO GROUP TO COVER THIS ROUGHLY IN THE 08Z TO 14Z TIME FRAME. FOR NOW I LEFT OUT ANY MENTION OF THUNDER IN THE TAFS WITH WEAKER LAPSE RATES ACROSS OUR AREA. WITH THE 09Z UPDATE I MAY HAVE TO ADD IN THUNDER CHANCES IF LIGHTNING STRIKES REMAIN IMPRESSIVE. ONCE THE INITIAL AREA OF RAIN MOVES TO THE EAST...NOTHING WIDESPREAD ENOUGH IS EXPECTED TO OCCUR TO INCLUDE IN THE TAFS. MVFR CIGS ARE POSSIBLE FOR A FEW HOURS BEFORE VFR RETURNS LATER THIS AFTERNOON. SOUTHWEST WINDS WILL SHIFT AROUND TO THE NW AFTER FRONT PASSES THIS AFTERNOON. GENERALLY WINDS WILL BE 5 TO 10 KTS BUT WE MAY SEE A FEW GUSTS ABOVE 10 KTS BEHIND THE FRONT THIS AFTERNOON. OUTLOOK... TUE NGT...A PD OF MVFR CIGS PSBL...SPCLY ACRS CNY. WED THRU SAT...MAINLY VFR. THE ONLY EXCEPTION WILL BE PSBL EARLY AM VLY FOG AT KELM. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS... NEAR TERM...KAH SHORT TERM... LONG TERM...CMG/MLJ AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS RALEIGH NC
327 PM EDT TUE AUG 13 2013 .SYNOPSIS... AHEAD OF A COLD FRONT THAT WILL TRACK SLOWLY THROUGH CENTRAL NORTH CAROLINA TONIGHT...A LEE SURFACE TROUGH WILL SHARPEN IN THE LEE OF THE APPALACHIANS THIS AFTERNOON. HIGH PRESSURE WILL BUILD INTO THE MIDDLE ATLANTIC REGION...WHILE THE FRONT STALLS AND BECOMES QUASI-STATIONARY ALONG THE CAROLINA COAST...MID TO LATE WEEK && .NEAR TERM /THROUGH TONIGHT/... AS OF 325 PM TUESDAY... THE NORTHWEST FRINGE OF AN AREA OF SCATTERED SHOWERS AND STORMS...FROM NEAR KVUJ TO KRDU TO KIXA...ROUGHLY CORRESPONDED AT 19Z TO A DIFFERENTIAL HEATING BOUNDARY ALONG AN EARLIER MID LEVEL CLOUD SHIELD ASSOCIATED WITH A LEAD IMPULSE STRETCHING FROM SE VA TO THE SC UPSTATE. MEANWHILE...A SECOND AREA OF SHOWERS AND STORMS CONTINUED TO BECOME BETTER ORGANIZED ALONG A LEE SURFACE TROUGH/ CONVERGENCE AXIS OVER WESTERN NC AND SW VA...AND IN ADVANCE OF A STRONGER MID LEVEL IMPULSE ROUGHLY ALIGNED ALONG THE CENTRAL- SOUTHERN APPALACHIANS. THE HRRR SUGGESTS THIS LATTER ACTIVITY WILL WEAKEN...BUT THIS SEEMS TO BE IN ERROR SINCE THE AGGREGATE COLD POOL HAS BECOME INCREASINGLY ORGANIZED AS IT PROPAGATES INTO AN INCREASINGLY UNSTABLE AIR MASS WITH TIME AND EASTWARD EXTENT DOWNSTREAM OVER CENTRAL NC. AS SUCH...THE MOST LIKELY SCENARIO IS THAT SCATTERED MAINLY MULTI-CELLULAR ACTIVITY WILL CONTINUE TO PERCOLATE OVER CENTRAL NC BEFORE THE AFOREMENTIONED WESTERN NC LINE IMPACTS A LARGER PERCENTAGE OF THE POPULATION AS IT CONTINUES SOUTHEASTWARD THROUGH THE EVENING HOURS. WHILE MULTI-CELL CLUSTERS SHOULD BE THE DOMINANT CONVECTIVE MODE WITH AN ASSOCIATED PRIMARY THREAT OF MARGINALLY SEVERE WIND GUSTS...SEASONABLY STRONG MID LEVEL FLOW ON THE ORDER OF 30-40 KTS (STRONGEST NORTH) PER 12Z RAOB AND MORE RECENT REGIONAL VWP DATA...WILL ALSO SUPPORT AT LEAST TRANSIENT SUPERCELLS... PARTICULARLY OVER THE NORTHERN COASTAL PLAIN AND NORTHEAST PIEDMONT...WHERE BOTH BUOYANCY AND BULK SHEAR WILL BE RELATIVELY MAXIMIZED. SEVERE WIND...AS WELL AS HAIL OWING TO DYNAMIC PRESSURE EFFECTS...WOULD BE ENHANCED WITH ANY SUCH SUPERCELLULAR MODE. RELATIVELY LONG AND STRAIGHT CURRENT AND FORECAST HODOGRAPHS SUGGEST A FEW STORM SPLITS WILL BE PROBABLE...WITH AN OTHERWISE WSW MEAN WIND VECTOR/STORM MOTION. SCATTERED TO NUMEROUS SHOWER AND STORM COVERAGE SHOULD DIMINISH FROM WEST TO EAST THROUGH MIDNIGHT. HOWEVER...A FEW WIDELY SCATTERED SHOWERS AND ISOLATED STORMS WILL BE POSSIBLE ALONG THE SYNOPTIC COLD FRONT - ONE STILL WELL WEST OF OUR REGION OVER THE EASTERN TN VALLEY AT 16Z - AS IT PASSES SLOWLY THROUGH OUR REGION OVERNIGHT. THERE MAY EVEN BE A LITTLE ANAFRONTAL LIGHT RAIN TOWARD THE FAR SOUTHEAST REACHES OF THE CWFA AROUND DAYBREAK...AS THE MID-UPPER TROUGH AXIS SHARPENS OVERHEAD. SINCE NWP GUIDANCE IS TYPICALLY TOO FAST/AGGRESSIVE WITH FRONTAL PASSAGES...ESPECIALLY THIS TIME OF YEAR...A CONTINUED VERY HUMID BOUNDARY LAYER OVER AT LEAST THE EASTERN THIRD OF THE CWFA FOR MUCH OF THE NIGHT WILL SUPPORT AREAS OF STRATUS AND FOG...PARTICULARLY IF MID LEVEL CLOUDINESS CLEARS SUFFICIENTLY IN THE WAKE OF THE EARLIER CONVECTION. LOWS IN THE UPPER 60S TO MIDDLE 70S. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 240 PM TUESDAY... THOUGH THE LOW LEVEL FRONTAL ZONE AND ASSOCIATED CHANCE OF SHOWERS AND STORMS SHOULD HAVE MOVED TO SOUTHEASTERN NC BY EARLY WED...NWP CROSS SECTIONS SUGGEST POST-FRONTAL HIGH-BASED STRATOCUMULUS WILL MAINTAIN MOSTLY CLOUDY CONDITIONS GENERALLY EAST OF I-95 THROUGH MIDDAY...WITH CONSIDERABLE CIRRUS LINGERING THROUGHOUT THE AFTERNOON. PARTLY TO MOSTLY SUNNY CONDITIONS SHOULD RULE ELSEWHERE. SURFACE HIGH PRESSURE AND ASSOCIATED NORTH NORTHEASTERLY LOW LEVEL FLOW...WHICH WILL GUST TO NEAR 20 MPH IN THE I-95 CORRIDOR LATE-MORNING TO EARLY AFTERNOON...WILL RESULT IN MILDER CONDITIONS AND MUCH LOWER HUMIDITY VALUES AS SURFACE DEWPOINTS DIP INTO THE 50S ACROSS THE PIEDMONT - HIGH TEMPERATURES RANGING FROM THE UPPER 70S TO NEAR 80 OVER THE NORTHERN COASTAL PLAIN...TO LOW-MID 80S SOUTHERN PIEDMONT AND WESTERN SANDHILLS. LINGERING BUT THINNING CIRRUS OVERNIGHT...WITH LOWS 60 TO 65 DEGREES...EXCEPT 55 TO 60 IN RURAL PIEDMONT LOCATIONS. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AS OF 230 PM TUESDAY... THE MODELS STILL SHOW SOME VARIABILITY AS TO WHERE THE COLD FRONT WILL STALL. THE GFS BRINGS THE FRONT ALMOST COMPLETELY THROUGH NC... KEEPING THE REGION DRIER THAN OTHER MODELS FOR THE REST OF THE WEEK. THE ECMWF DOES NOT PUSH THE FRONT AS FAR SUGGESTING THAT THE SOUTHERN AND EASTERN PORTION OF NC COULD SEE A MUCH HIGHER QPF. AS POINTED TO IN PREVIOUS DISCUSSIONS... HIGH SURFACE PRESSURE IN THE NORTHEAST COULD ALLOW FOR A WARM SEASON CAD TO FORM IN THE LEE OF THE APPALACHIANS WITH A WEDGE FRONT DRAPED ACROSS CENTRAL NC LATE IN THE WEEK. HOW FAR THE FRONT WILL PROPAGATE REMAINS A TOPIC OF DISCUSSION AS THE GFS PUSHES THIS FRONT ALL THE WAY THROUGH NC WITH THE ECMWF DEPICTING A SHARPER...POSSIBLY MORE REALISTIC...BOUNDARY SETTING UP JUST EAST OF THE FOOTHILLS AND ACROSS THE WESTERN PIEDMONT. LOW PRESSURE IN THE GULF SHOULD ALSO BRING HIGH THETA-E PARCELS UP THE EAST COAST CREATING VERY MOIST CONDITIONS FOR THE WEEKEND. THE FRONT WILL BEGIN TO STALL OVER EASTERN NC ON THURSDAY. MODEL UNCERTAINTY IN THE EXACT LOCATION OF WHERE THE FRONT WILL STALL WILL AFFECT QPF AMOUNTS WITH THE GFS CONFINING PRECIP TO THE COAST WHEREAS THE ECMWF SETS UP THE FRONT CLOSER TO THE I-95 CORRIDOR. CLIMATOLOGY AND NORMAL DIURNAL PROCESSES WOULD SUGGEST THAT THE ECMWF SOLUTION WOULD BE FAVORED AT THIS TIME AND AT LEAST SOME QPF WOULD BE REALIZED EAST OF I-95. AS CAD CONDITIONS LOCK IN ON FRIDAY AND SATURDAY...SEVERAL SHORTWAVE IMPULSES WILL TRAIN UP THE SOUTHEAST COAST PROVIDING BETTER DYNAMICS FOR HEAVIER RAINFALL...AT LEAST FROM THE TRIANGLE EASTWARD...WITH MORE OVERRUNNING PRECIP IN THE NORTHWEST DUE TO ISENTROPIC LIFT. IF THE WEDGE FRONT IS PINNED BACK FARTHER TO THE WEST...THEN THE POSSIBILITY FOR SEVERE STORMS IN THE EASTERN PORTION OF THE CWA BECOMES GREATER BUT MODELS ARE STARTING TO DOWNPLAY THIS SCENARIO AND SHOW MORE OF A NORTHEASTERLY FLOW REGIME FOR MOST OF THE AREA WITH LITTLE LOW-LEVEL SHEAR OR HELICITY AVAILABLE THROUGH SUNDAY MORNING. THIS STARTS TO CHANGE A BIT ON SUNDAY AFTERNOON AS AT LEAST KFAY AND KRWI BEGIN TO SWITCH BACK TO A SOUTHERLY FLOW REGIME. MODEL FORECAST SOUNDINGS SHOW THAT BY THE TIME DESTABILIZATION OCCURS BOTH SITES COULD HAVE SOUTHWESTERLY FLOW KEEPING BULK SHEER (PRIMARILY SPEED SHEER) DOWN TO 20 KNOTS OR SO WITH CLOSE TO 1000 J/KG OF INSTABILITY. WHILE HEAVY RAIN AND FLOODING WOULD BE THE PRIMARY THREAT...SMALL INVERTED-V SIGNATURES SUGGEST THAT WINDS COULD BE A POSSIBLE SECONDARY THREAT. AS AN ASIDE THE NHC IS STILL NOT BUYING INTO THE TROPICAL SYSTEM THAT THE GFS IS SPINNING UP IN THE NORTHERN GULF ON FRIDAY EVENING DUE TO UNFAVORABLE UPPER LEVEL CONDITIONS. THAT BEING SAID A ECMWF SOLUTION OF A MORE CONSTANT FLOW OF MOISTURE OUT OF THE GULF IS MORE LIKELY WITH SMALLER SHORTWAVE IMPULSES ENHANCING THE FLOW. THE PRESENCE OF THE SAME MOIST AIR MASS WILL CONTINUE TO PRODUCE UNSETTLED CONDITIONS WITH MORE PRECIPITATION INTO EARLY NEXT WEEK ALTHOUGH THERE IS A FAIR AMOUNT OF MODEL UNCERTAINTY AT THE END OF THE LONG TERM DEPENDING ON HOW EVENTS UNFOLD THIS WEEKEND. WILL KEEP AT LEAST CHANCE POPS THROUGH THE END OF THE PERIOD. TEMPERATURES IN THE LOW TO MID 80S ON WEDNESDAY SHOULD DROP IN TO THE UPPER 70S FOR MUCH OF THE PERIOD DUE TO THE FRONTAL PASSAGE AND POTENTIAL CAD. THICKNESS VALUES AS LOW AS 1370 IN THE TRIAD ARE VALUES TYPICALLY SEEN IN EARLY MAY AS OPPOSED TO THE MIDDLE OF AUGUST. HIGH DEWPOINTS SHOULD ALLOW FOR THE MIN TEMP TO REMAIN AROUND NORMAL IN THE MID 60S. A WARMING TREND SHOULD ALLOW FOR MAX TEMPS TO REACH THE UPPER 80S AND MIN TEMPS IN TO THE UPPER 60S BY THE END OF THE PERIOD...WITH HIGHEST TEMPS IN THE SE AND REMAINING COOLER IN THE NORTHWEST PIEDMONT. && .AVIATION /18Z TUESDAY THROUGH SATURDAY/... AS OF 220 PM TUESDAY... SCATTERED SHOWERS AND STORMS THIS AFTERNOON WILL BECOME MORE NUMEROUS...LIKELY IN THE FORM OF A BROKEN LINE THAT WAS DEVELOPING OVER NW NC AND SW VA AS OF 18Z. THESE SHOWERS AND STORMS - AND ASSOCIATED SUB-VFR CONDITIONS AND GUSTY WINDS - ARE LIKELY TO IMPACT...FROM NORTHWEST TO SOUTHEAST...THE TRIAD TERMINALS TO KRDU AND KRWI BETWEEN 20Z AND 02Z. THERE WILL REMAIN A LINGERING CHANCE OF A SHOWER OR STORM UNTIL A COLD FRONT SLOWLY CROSSES OUR REGION TONIGHT. IN ADDITION...AREAS OF FOG OR LOW STRATUS WILL BE PROBABLE...MAINLY AT EASTERN TERMINALS...WHERE THE FRONTAL PASSAGE WILL LIKELY BE DELAYED UNTIL AROUND SUNRISE. SOUTHWEST WINDS AHEAD OF THE FRONT WILL VEER TO NORTHWESTERLY...THEN NORTH NORTHEASTERLY WITH GUSTS OF 15-20 KTS...LATE MORNING TO EARLY AFTERNOON WED. LOOKING AHEAD: A WAVE OF LOW PRESSURE WILL DEVELOP ALONG A FRONTAL ZONE STALLED ALONG THE SOUTHEAST US COAST...AND RESULT IN A CHANCE OF SUB-VFR CONDITIONS AND RAIN LATE WEEK-EARLY THIS WEEKEND. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...ELLIS/CR AVIATION...MWS
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
303 PM EDT TUE AUG 13 2013 .SYNOPSIS... A FRONT WILL APPROACH THE AREA TONIGHT AND MOVE THROUGH EASTERN NORTH CAROLINA AROUND SUNRISE WEDNESDAY. FRONT WILL STALL ALONG THE COAST THROUGH THE REMAINDER OF THE WEEK AND THE WEEKEND AS WAVES OF LOW PRESSURES MOVE ALONG IT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 152 PM TUE...MODELS IN DECENT AGREEMENT ON TIMING OF APPROACHING FRONT WITH NAM BEING A COUPLE OF HOURS SLOWER IN BRINGING FRONT THROUGH EASTERN NORTH CAROLINA. HRRR HAS GOOD HANDLE ON DEVELOPING ACTIVITY THIS AFTERNOON (RUC AND WRF NOT SHOWING ANY PRECIP FOR THE NEXT FEW HOURS)...AND INDICATES AN INCREASE IN COVERAGE AFTER SUNSET. BROAD UPPER TROUGH OVER THE EAST WITH A SERIES OF WEAK MID-LEVEL PIECES OF ENERGY ROTATING AROUND IT WILL KEEP THE FORECAST PERIOD UNSETTLED. FORECAST SOUNDINGS SHOWING CAPES INCREASING OVERNIGHT FROM 2K TO AROUND 3.5K WITH LIS AROUND -5 AND PWS OVER 2 INCHES. WILL HAVE A CONTINUING CHANCE OF THUNDERSTORMS OVER NIGHT...SOME OF WHICH COULD HAVE HEAVY RAIN WITH LOCALIZED FLOODING IN THE MODERATE MID LEVEL LAYER FLOW AND HIGH PWS. FRONT WILL ENTER THE COASTAL PLAINS BEFORE SUNRISE. && .SHORT TERM /WEDNESDAY/... AS OF 155 PM TUE...FRONT WILL MOVE THROUGH THE COASTAL AREAS AROUND MID MORNING. DRIER COOLER ATMOSPHERE WILL MOVE OVER THE AREA WITH HIGH TEMPERATURES IN THE LOWER TO MIDDLE 80S IN THE NORTHERLY FLOW...AND A DECREASE IN CLOUD COVER. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... AS OF 3 PM TUE...BELOW NORMAL TEMPS AND ABOVE NORMAL PRECIP EXPECTED THROUGH THE PERIOD. A FRONT WILL STALL OFF THE NC COAST WED NIGHT THROUGH THE WEEKEND WITH AREAS OF LOW PRESSURE MOVING ALONG THE BOUNDARY...AND SFC HIGH PRESSURE BUILDING NORTH OF THE AREA. ONLY SIG CHANGE TO PREVIOUS FORECAST WAS TO TRIM POPS BACK SLIGHTLY...WITH MODELS NOW COMING IN QUITE A BIT DRIER WED NIGHT INTO FRI...ESP FOR AREAS IN THE NORTHERN TIER. COULD SEE A SHARP PRECIP GRADIENT SET UP WED NIGHT THROUGH FRI...WHERE BEST PRECIP CHANCES WILL BE ALONG THE COAST AND SOUTHERN TIER. FRONT WILL LIKELY MOVE CLOSER TO THE COAST FRI INTO THE WEEKEND WITH WEAK WAVES MOVING ALONG IT. WILL CONTINUE HIGH CHANCE POPS THIS WEEKEND. LOW LEVEL THICKNESS VALUES...NELY FLOW AND ABUNDANT CLOUD COVER AND PRECIP SUPPORT HIGH TEMPS IN THE UPPER 70S TO LOWER 80S THROUGH THE WEEKEND...WITH OVERNIGHT LOWS IN THE MID 60S/LOWER 70S. MODEL DIFFERENCES CONTINUE EARLY NEXT WEEK BTWN GFS/ECMWF...BUT AT THIS TIME IT LOOKS LIKE SLY FLOW WILL RETURN...WITH TEMPS SLOWLY WARMING AS UPPER RIDGE BEGINS TO REBUILD OVER THE SE. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... SHORT TERM /THROUGH 18Z WEDNESDAY/... AS OF 1245 PM TUE...SHOWERS AND THUNDERSTORMS HAVE FORMED OVER EASTERN NORTH CAROLINA THIS AFTERNOON...AND COVERAGE IS EXPECTED TO INCREASE THROUGH THE DAY. WILL HAVE MVFR WITH OCCASIONAL IFR IN CIG AND VIS WITH THESE STORMS. BROKEN LINE OF STORMS AHEAD OF APPROACHING FRONT IS EXPECTED TO MOVE THROUGH THE AREA AFTER SUNSET. DECREASED COVERAGE AFTER MIDNIGHT BUT WILL HAVE SOME STRATUS FORMING. FRONTAL PASSAGE EXPECTED AROUND SUNRISE WITH WIND SHIFTING TO NORTH NORTHEASTERLY. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 3 PM TUE...FRONT WILL STALL OFF THE NC COAST WED NIGHT THROUGH LATE WEEK WITH AREAS OF LOW PRESSURE MOVING ALONG IT. PERIODS OF SUB-VFR CONDITIONS LIKELY WED NIGHT THROUGH THE WEEKEND WITH PRED NELY FLOW AND GOOD MOISTURE. SCT SHOWERS AND ISO TSTMS EXPECTED EACH DAY. && .MARINE... SHORT TERM /THROUGH WEDNESDAY/... AS OF 159 PM TUE...SOUTHWEST FLOW WILL INCREASE TO AROUND 20 KNOTS THIS EVENING AS GRADIENT INCREASES IN ADVANCE OF APPROACHING FRONT. MAY SEE SOME GUSTS TO 25 KNOTS AND SEAS COULD REACH 6 FEET IN THE CENTRAL OUTER WATERS. THEREFORE WILL KEEP SCA UP. STRONG STORMS ARE POSSIBLE THROUGH MUCH OF THE NIGHT WITH GUSTY WINDS AND HEAVY RAIN. FRONT EXPECTED TO MOVE THROUGH THE WATERS DURING THE MORNING WEDNESDAY WITH WIND SHIFTING TO NORTH NORTHEASTERLY AND DIMINISHING IN SPEED TO AROUND 15 KNOTS. SEAS WILL DROP TO 3 TO 4 FEET WEDNESDAY. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 3 PM TUE...FRONT WILL STALL OFF THE NC COAST WED NIGHT THROUGH THE WEEKEND WITH WAVES OF LOW PRESSURE MOVING ALONG IT. A PERIOD OF MODERATE NE FLOW 10-20KT IS EXPECTED TO CONTINUE WED NIGHT INTO THU NIGHT WITH SEAS UP TO 5FT...THEN DIMINISH TO 10-15KT FRI WITH SEAS 2-4FT. CONFIDENCE IS LOW REGARDING WIND DIRECTIONS FOR THIS WEEKEND...AS MODELS CONTINUE TO DIFFER HANDLING EXACT PLACEMENT OF FRONT IN COASTAL WATERS. THOUGH EXPECT WINDS AOB 15KT THIS WEEKEND WITH SEAS 2-3FT. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR AMZ152-154. && $$ SYNOPSIS...CGG/CQD NEAR TERM...CGG SHORT TERM...CGG LONG TERM...CQD AVIATION...CGG/CQD MARINE...CGG/CQD
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
323 AM EDT TUE AUG 13 2013 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN ACROSS THE REGION TODAY BEHIND A DEPARTING COLD FRONT. FAIR WEATHER WITH BELOW NORMAL TEMPERATURES AND PARTLY CLOUDY SKIES ARE EXPECTED FOR THE REMAINDER OF THE WORK WEEK. THE HIGH WILL WEAKEN OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PRE FRONTAL PRECIPITATION ACROSS THE OHIO RIVER WILL GRADUALLY SHIFT SOUTHEASTWARD THIS MORNING. COLD FRONT CURRENTLY LOCATED ALONG AN INDIANAPOLIS TO LIMA LINE WILL CONTINUE ITS PROGRESSION SOUTHEASTWARD THIS MORNING. BY THE LATE MORNING THIS FRONT IS EXPECTED TO HAVE CLEARED ALL OF OUR ZONES. ANY LINGERING PRECIPITATION ACROSS THE SOUTHEAST WILL END THIS MORNING AS THE FRONT PASSES. NORTHWESTERLY FLOW WILL INCREASE DURING THE DAY AS HIGH PRESSURE BUILDS SOUTHEASTWARD OUT OF CENTRAL CANADA. EXPECT WINDS AROUND 15 MPH GUSTING UP TO 25 MPH AT TIMES DURING THE AFTERNOON. THERE IS NOT MUCH MOISTURE TO SPEAK OF BEHIND THE FRONT EXCEPT FOR THAT WHICH WILL ORIGINATE FROM EVAPORATION OFF THE GREAT LAKES. THEREFORE AM EXPECTING MOSTLY SUNNY SKIES THIS AFTERNOON. COLD ADVECTION TODAY WILL KEEP TEMPERATURES FROM RISING ABOVE THE MIDDLE 70S ACROSS THE NORTH TO NEAR 80 ACROSS THE SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... HIGH PRESSURE WILL DOMINATE OUR WEATHER THROUGH THURSDAY NIGHT. EXPECT MOSTLY CLEAR SKIES WITH LIGHT WINDS UNDER THIS DRY AIRMASS. HIGH TEMPERATURES WILL BE IN THE LOW TO MIDDLE 70S ON WEDNESDAY AND THE MIDDLE TO UPPER 70S ON THURSDAY. NIGHTTIME LOWS WILL BE IN THE LOW 50S TONIGHT AND WEDNESDAY NIGHT...WITH A FEW LOCATIONS DROPPING ITO THE UPPER 40S WEDNESDAY NIGHT. OVERNIGHT LOWS THURSDAY NIGHT WILL BE A TAD WARMER THAN WEDNESDAY NIGHT. HOWEVER... THESE VALUES WILL STILL BE A SEASONABLY COOL MIDDLE TO UPPER 50S FOR THE MOST PART. && .LONG TERM /FRIDAY THROUGH MONDAY/... PERIOD BEGINS WITH A HIGH PRESSURE AREA STRETCHING ACROSS THE OHIO VALLEY. THE HIGH WILL REMAIN ANCHORED OVER THE REGION THURSDAY AND FRIDAY. MEANWHILE MODELS DROP MORE ENERGY INTO THE ERN U.S. H5 TROF ON FRIDAY...CREATING A CUTOFF H5 LOW OVER THE MID MS VALLEY. THIS MIGHT ACT TO LOWER THE CHANCE OF PCPN OVER THE WEEKEND. THE GFS IS STILL THE QUICKEST WITH THE RETURN FLOW OF MOISTURE ON SATURDAY. KEPT A 20 TO 30 PERCENT CHC ON THE SOUTH AND SOUTHWEST FOR SATURDAY. AS THE UPPER LOW DRIFTS SLOWLY E...SCT PCPN REMAINS A POSSIBILITY ON SUNDAY WITH A BETTER CHANCE ON MONDAY AS AN INVERTED SFC TROF FOCUS THE MOISTURE ACROSS THE REGION. HIGHS WILL SLOWLY MODERATE...RISING FROM THE MID TO UPPER 70S ON THURSDAY TO THE 80S OVER THE WEEKEND. LOWS WILL RISE FROM THE MID TO UPPER 50S FRIDAY MORNING INTO THE 60S FOR THE WEEKEND. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE CONTINUING ACROSS THE AREA EARLY THIS MORNING. THIS IS AHEAD OF A COLD FRONT THAT WILL PUSH DOWN ACROSS THE REGION THROUGH LATE MORNING. THE SHOWERS HAVE BEEN SHOWING A DECREASING TREND OVER THE LAST SEVERAL HOURS AND THE LAST FEW RUNS OF THE HRRR AND THE 00Z NAM ARE PICKING UP ON THIS. AS A RESULT...CHANCES OF SEEING PCPN AT THE ACTUAL TAF SITES MAY BE RELATIVELY LOW...WITH A BETTER CHANCE OF REDEVELOPMENT SOUTHEAST OF THE TAF SITES LATER THIS MORNING. CIGS ARE GENERALLY RUNNING VFR AT THE MOMENT BUT DO EXPECT TO SEE THEM DROP DOWN INTO MVFR CATEGORY LATER THIS MORNING AS WE START TO GET INTO SOME LOW LEVEL CAA. ANY LOWER CLOUDS WILL SLOWLY LIFT INTO A VFR DECK THROUGH LATE MORNING/EARLY AFTERNOON. OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...LATTO NEAR TERM...LATTO SHORT TERM...LATTO LONG TERM...SITES AVIATION...JGL
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
144 AM EDT TUE AUG 13 2013 .SYNOPSIS... A COLD FRONT WILL MOVE EAST AND CROSS THE OHIO VALLEY TONIGHT. HIGH PRESSURE AND A COOLER...DRIER AIRMASS WILL THEN SETTLE INTO THE AREA FOR THE MID TO LATER PART OF THE WEEK. THIS HIGH WILL SLOWLY ERODE AT THE START OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... WITH THUNDERSTORMS HAVING BLOSSOMED IN A VERY MOIST AIRMASS THIS EVENING...HAVE INCREASED POPS TO LIKELY OVER MUCH OF THE AREA. ADDITIONAL THUNDERSTORMS WILL BE LIKELY LATE TONIGHT AS A COLD FRONT MAKES ITS WAY ACROSS THE AREA FROM THE NORTHWEST. TEMPERATURES WILL NOT FALL OFF MUCH TONIGHT...WITH LOWS AROUND 70. A FEW MARGINALLY STRONG THUNDERSTORMS ARE DEVELOPING. WITH A HIGH WET BULB ZERO HEIGHT INDICATING A LIMITED LARGE HAIL POTENTIAL...AND WITH WINDS ALOFT BEING A BIT WEAK...MAIN THREAT APPEARS TO BE HEAVY RAIN...ESPECIALLY WITH PRECIPITABLE WATER BEING OVER 2 INCHES ACROSS THE SOUTH. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... THINGS WILL DRY OUT NICELY BEHIND THE FRONT AND HIGH TEMPERATURES WILL BE IN THE 70S WITH NIGHTTIME LOWS DROPPING INTO THE LOW TO MID 50S UNDER GENERALLY CLEAR SKIES. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... PERIOD BEGINS WITH A HIGH PRESSURE AREA STRETCHING ACROSS THE OHIO VALLEY. THE HIGH WILL REMAIN ANCHORED OVER THE REGION THURSDAY AND FRIDAY. MEANWHILE MODELS DROP MORE ENERGY INTO THE ERN U.S. H5 TROF ON FRIDAY...CREATING A CUTOFF H5 LOW OVER THE MID MS VALLEY. THIS MIGHT ACT TO LOWER THE CHANCE OF PCPN OVER THE WEEKEND. THE GFS IS STILL THE QUICKEST WITH THE RETURN FLOW OF MOISTURE ON SATURDAY. KEPT A 20 TO 30 PERCENT CHC ON THE SOUTH AND SOUTHWEST FOR SATURDAY. AS THE UPPER LOW DRIFTS SLOWLY E...SCT PCPN REMAINS A POSSIBILITY ON SUNDAY WITH A BETTER CHANCE ON MONDAY AS AN INVERTED SFC TROF FOCUS THE MOISTURE ACROSS THE REGION. HIGHS WILL SLOWLY MODERATE...RISING FROM THE MID TO UPPER 70S ON THURSDAY TO THE 80S OVER THE WEEKEND. LOWS WILL RISE FROM THE MID TO UPPER 50S FRIDAY MORNING INTO THE 60S FOR THE WEEKEND. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE CONTINUING ACROSS THE AREA EARLY THIS MORNING. THIS IS AHEAD OF A COLD FRONT THAT WILL PUSH DOWN ACROSS THE REGION THROUGH LATE MORNING. THE SHOWERS HAVE BEEN SHOWING A DECREASING TREND OVER THE LAST SEVERAL HOURS AND THE LAST FEW RUNS OF THE HRRR AND THE 00Z NAM ARE PICKING UP ON THIS. AS A RESULT...CHANCES OF SEEING PCPN AT THE ACTUAL TAF SITES MAY BE RELATIVELY LOW...WITH A BETTER CHANCE OF REDEVELOPMENT SOUTHEAST OF THE TAF SITES LATER THIS MORNING. CIGS ARE GENERALLY RUNNING VFR AT THE MOMENT BUT DO EXPECT TO SEE THEM DROP DOWN INTO MVFR CATEGORY LATER THIS MORNING AS WE START TO GET INTO SOME LOW LEVEL CAA. ANY LOWER CLOUDS WILL SLOWLY LIFT INTO A VFR DECK THROUGH LATE MORNING/EARLY AFTERNOON. OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...FRANKS NEAR TERM...CONIGLIO/FRANKS SHORT TERM...FRANKS LONG TERM...SITES AVIATION...JGL
AREA FORECAST DISCUSSION
NWS NORMAN OK
628 AM CDT TUE AUG 13 2013 .DISCUSSION... PLEASE SEE THE 12Z AVIATION DISCUSSION BELOW. && .AVIATION... A LINE OF SHOWERS AND THUNDERSTORMS WILL SLOWLY CONTINUE TO DRIFT SOUTHWARD THROUGHOUT THE DAY. EXPECT AT LEAST MVFR TO APPLY OVER MOST TERMINALS UNTIL PERHAPS LATER THIS AFTERNOON AND THIS EVENING. GAG AND WWR WILL HAVE THE BEST FLIGHT CONDITIONS THROUGH TODAY WITH ONLY BRIEF MVFR A POSSIBILITY EARLY THIS MORNING. HOWEVER...THERE WILL STILL BE A CHANCE FOR TSRA THERE LATER THIS AFTERNOON. CONFIDENCE IS NOT VERY HIGH REGARDING THE PREVIOUS THOUGH SO WILL ONLY INCLUDE PROB30S FOR NOW. MVFR TO IFR CIGS ARE EXPECTED FROM AROUND 09-12Z TOMORROW BEHIND THIS COLD FRONT. && .PREV DISCUSSION... /ISSUED 352 AM CDT TUE AUG 13 2013/ DISCUSSION... MOIST CONVECTION HAS INCREASED ALONG THE 925 MB BAROCLINIC ZONE EARLY THIS MORNING. THE NAM12 AND RUC13 ARE DEPICTING THIS VERY WELL...AND INDICATE THE BEST WAA WILL OCCUR BETWEEN NOW THROUGH ABOUT 12Z BEFORE THE FRONT BEGINS TO NUDGE SOUTHWARD. SLOW MOVING STORMS ALONG THIS ZONE...TRAINING...AND VERY HIGH PWATS (OUN 00Z 1.92 IN) WILL SUPPORT HIGH RAINFALL RATES THROUGH EARLY THIS MORNING. BY THIS AFTERNOON AND EVENING...A SHORTWAVE TROUGH MOVING OUT OF KS WILL MOST LIKELY RESULT IN REDEVELOPMENT ACROSS MUCH OF THE AREA. THE HEAVIEST RAIN IS EXPECTED ACROSS PORTIONS OF SOUTHERN OK THIS AFTERNOON AND EVENING...AND PERHAPS EVEN W N TX NEAR THE BOUNDARY LATE TONIGHT. THEREFORE...WILL EXTEND FFA SOUTHWARD TO INCLUDE SOUTHERN PORTIONS OF OK WHERE SOME LOCALIZED HEAVY RAINFALL ALREADY OCCURRED YESTERDAY. RAIN CHANCES WILL SHIFT SOUTHWARD WITH THE BOUNDARY LATE TONIGHT THROUGH EARLY WED MORNING. WILL KEEP MAX TEMPS CLOSE TO THE MET GUIDANCE FOR TODAY CONSIDERING PERSISTENT STRATUS AND PRECIP CHCS THROUGH THE DAY. SOME PARTS OF THE OKC METRO MAY NOT MAKE IT OUT OF THE 70S. A SFC RIDGE WILL EXTEND THROUGH THE FA FROM THE NE WED BEHIND THE FRONT KEEPING TEMPS WELL BELOW NORMAL. NORTHERLY FLOW ALOFT WILL CONTINUE OVERHEAD THROUGH THE WORK WEEK...WITH THE POSSIBILITY OF ADDITIONAL SUBTLE SHORTWAVE TROUGHS MOVING OVER THE PLAINS. POPS WILL INCREASE AGAIN ON THURSDAY AS ONE SUCH WAVE TRAVERSES THE REGION. AN EVEN MORE SIGNFICANT MID TO UPPER SHORTWAVE TROUGH IS ANTICIPATED BY FRIDAY SO DECIDED TO INCREASE POPS TO AT LEAST CHC. OVERALL...EXPECT AN UNUSUALLY COOL AND MOIST FORECAST THROUGH THE ENTIRE FORECAST PERIOD AS NORTHERLY MID LEVEL FLOW REMAINS IN PLACE WITH THE UPPER RIDGE AXIS WEST OF THE REGION. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 81 69 83 67 / 80 40 20 10 HOBART OK 84 69 86 68 / 70 40 30 10 WICHITA FALLS TX 96 73 89 70 / 50 60 40 20 GAGE OK 80 65 82 64 / 60 40 20 20 PONCA CITY OK 82 66 82 64 / 50 40 20 10 DURANT OK 90 73 87 67 / 70 60 50 20 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR OKZ004>032-040>043- 047-048. TX...NONE. && $$ 02/03/03
AREA FORECAST DISCUSSION
NWS NORMAN OK
352 AM CDT TUE AUG 13 2013 .DISCUSSION... MOIST CONVECTION HAS INCREASED ALONG THE 925 MB BAROCLINIC ZONE EARLY THIS MORNING. THE NAM12 AND RUC13 ARE DEPICTING THIS VERY WELL...AND INDICATE THE BEST WAA WILL OCCUR BETWEEN NOW THROUGH ABOUT 12Z BEFORE THE FRONT BEGINS TO NUDGE SOUTHWARD. SLOW MOVING STORMS ALONG THIS ZONE...TRAINING...AND VERY HIGH PWATS (OUN 00Z 1.92 IN) WILL SUPPORT HIGH RAINFALL RATES THROUGH EARLY THIS MORNING. BY THIS AFTERNOON AND EVENING...A SHORTWAVE TROUGH MOVING OUT OF KS WILL MOST LIKELY RESULT IN REDEVELOPMENT ACROSS MUCH OF THE AREA. THE HEAVIEST RAIN IS EXPECTED ACROSS PORTIONS OF SOUTHERN OK THIS AFTERNOON AND EVENING...AND PERHAPS EVEN W N TX NEAR THE BOUNDARY LATE TONIGHT. THEREFORE...WILL EXTEND FFA SOUTHWARD TO INCLUDE SOUTHERN PORTIONS OF OK WHERE SOME LOCALIZED HEAVY RAINFALL ALREADY OCCURRED YESTERDAY. RAIN CHANCES WILL SHIFT SOUTHWARD WITH THE BOUNDARY LATE TONIGHT THROUGH EARLY WED MORNING. WILL KEEP MAX TEMPS CLOSE TO THE MET GUIDANCE FOR TODAY CONSIDERING PERSISTENT STRATUS AND PRECIP CHCS THROUGH THE DAY. SOME PARTS OF THE OKC METRO MAY NOT MAKE IT OUT OF THE 70S. A SFC RIDGE WILL EXTEND THROUGH THE FA FROM THE NE WED BEHIND THE FRONT KEEPING TEMPS WELL BELOW NORMAL. NORTHERLY FLOW ALOFT WILL CONTINUE OVERHEAD THROUGH THE WORK WEEK...WITH THE POSSIBILITY OF ADDITIONAL SUBTLE SHORTWAVE TROUGHS MOVING OVER THE PLAINS. POPS WILL INCREASE AGAIN ON THURSDAY AS ONE SUCH WAVE TRAVERSES THE REGION. AN EVEN MORE SIGNFICANT MID TO UPPER SHORTWAVE TROUGH IS ANTICIPATED BY FRIDAY SO DECIDED TO INCREASE POPS TO AT LEAST CHC. OVERALL...EXPECT AN UNUSUALLY COOL AND MOIST FORECAST THROUGH THE ENTIRE FORECAST PERIOD AS NORTHERLY MID LEVEL FLOW REMAINS IN PLACE WITH THE UPPER RIDGE AXIS WEST OF THE REGION. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 81 69 83 67 / 80 40 20 10 HOBART OK 84 69 86 68 / 70 40 30 10 WICHITA FALLS TX 96 73 89 70 / 50 60 40 20 GAGE OK 80 65 82 64 / 60 40 20 20 PONCA CITY OK 82 66 82 64 / 50 40 20 10 DURANT OK 90 73 87 67 / 70 60 50 20 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR OKZ004>032-040>043- 047-048. TX...NONE. && $$ 02/03
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
956 PM CDT WED AUG 14 2013 .UPDATE... MADE A COUPLE OF ADJUSTMENTS TO THE FORECAST FOR THE REMAINDER OF TONIGHT. ADDED PATCHY FOG FOR EARLY TOMORROW MORNING FOR AREAS PRIMARILY ALONG AND WEST OF THE MISSOURI RIVER. LOW STRATUS DECK NOTED ON SATL AROUND WINNER AND IS PUSHING NWWD THIS EVENING. LOW LEVEL MOISTURE ANTICIPATED TO INCREASE THE MISSOURI RIVER VALLEY PARTICULARLY AROUND KPIR AND SOUTH WHERE RAIN MOVED THROUGH EARLY THIS MORNING. ALSO ADJUSTED SKY COVER A BIT ACROSS THE NE CWA TO ACCOUNT FOR SOME MID LVL CLOUDS ACROSS EASTERN NODAK AS THEY ARE PUSHING SEWD THIS EVENING. ASSOC SHRA ACTIVITY AROUND JAMESTOWN IS NOT EXPECTED TO MAKE IT FAR ENOUGH SOUTH TO AFFECT NERN ZONES. RETAINED POPS ACROSS THE WEST FOR LATE TONIGHT AS SHORTWAVE ENERGY APPROACHES WESTERN SOUTH DAKOTA FROM THE NORTHWEST. && .PREVIOUS DISCUSSION... .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT PRETTY QUIET ACROSS THE CWA THIS AFTERNOON BUT WILL BE WATCHING THE WESTERN CWA OVER THE NEXT FEW HOURS FOR THE POTENTIAL FOR A FEW ISOLD THUNDERSHOWERS AS SHORTWAVE ENERGY APPROACHES FROM THE MIDWEST. BEST SUPPORT DOES NOT ARRIVE UNTIL LATER THIS EVENING...BUT DAYTIME HEATING ACROSS THE WESTERN CWA HAS ALLOWED MLCAPE TO APPROACH 1000 J/KG. SHEAR IS LACKING ONCE AGAIN AS HAS BEEN THE CASE THE PAST FEW DAYS. CURRENTLY SEEING A CONGESTED CU FIELD ACROSS NORTH CENTRAL SD WITH RADAR ECHOES JUST BEGINNING TO INCREASE OVER CORSON COUNTY. HRRR ACTUALLY PICKING UP ON THIS AND SHOWING A FEW POPCORN TYPE LIGHT SHOWERS OR MAYBE A MODERATE THUNDERSHOWER THROUGH LATE AFTERNOON. WILL MAINTAIN SLIGHT CHANCE POPS FOR THE WESTERN CWA THROUGH THE AFTERNOON. MAIN SHORTWAVE ENERGY APPROACHES THE REGION LATER THIS EVENING...BUT MODELS NOT TOO IMPRESSED WITH THIS FOR OUR CWA. 12Z NSSL WRF SHOWS A LINE OF SHOWERS AND STORMS MOVING INTO WESTERN SD LATER THIS EVENING BUT DIES OUT AS ITS ENTERING THE WESTERN CWA. WILL MAINTAIN SMALL POPS OVERNIGHT AS WELL...BUT HAVE TRIMMED THINGS DOWN TO DRY FOR THE EASTERN CWA AS THERE JUST DOESNT SEEM TO BE ANY SUPPORT FOR PRECIP. THERE REALLY IS NO LOW LEVEL JET TO SPEAK OF OVERNIGHT EITHER. WEAK SHORTWAVE ENERGY MOVES SOUTHEAST OVER THE AREA ON THURSDAY BUT MODELS KEEP TRENDING DRIER AND DRIER FOR THIS...TO THE POINT NOW WHERE MOST MODELS ARENT EVEN SHOWING ANY PRECIP FOR THE AREA. HAVE SCALED BACK POPS QUITE A BIT...GOING DRY IN PLACES BUT KEEPING A SLIGHT CHANCE GOING FOR MOST PLACES. AFTER THURSDAY...THE WARM UP BEGINS AS UPPER RIDGING BUILDS OVER THE HIGH PLAINS AND DAKOTAS. .LONG TERM...SATURDAY THROUGH WEDNESDAY MAIN CHALLENGE IN THE LONG TERM WILL BE PRECIP CHANCES UNDER THE DOMINANT UPPER RIDGE. MODELS ARE NOT IN GOOD AGREEMENT TODAY IN THE EXTENDED. TOSSED OUT THE GEM AS IT IS THE ONLY MODEL SHOWING A DEVELOPING TROPICAL SYSTEM IN THE GULF THIS WEEKEND. THIS MAY CONTAMINATE QPF AND PRESSURE FIELDS ALL THE WAY NORTH INTO THE DAKOTAS. GFS AND ECMWF ARE BOTH FLIP FLOPPING WITH MOISTURE FIELDS THOUGH SFC PRESSURE PROGS ARE SIMILAR. BOTH MODELS SHOW TWO TROFS MOVING ACROSS THE DAKOTAS...ONE SUNDAY NIGHT/MONDAY AND ANOTHER TUESDAY NIGHT/WEDNESDAY. HOWEVER THE GFS IS WET FOR THE FIRST AND DRY FOR THE SECOND WHILE THE ECMWF IS OPPOSITE. STUCK WITH ALLBLEND POPS SUNDAY NIGHT/MONDAY AS 30S/40S SEEM REASONABLE AT THIS POINT. WENT DRIER THAN ALLBLEND FOR THE END OF THE PERIOD BASED ON INTER OFFICE COLLABORATION. TEMPERATURES SHOULD BE ON THE RISE THROUGH THE PERIOD WITH HIGHS IN THE UPPER 80S TO LOWER 90S EXPECTED. && .AVIATION... 00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS FAIRLY TRANQUIL CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE LOCAL TERMINALS AS THE REGION REMAINS BETWEEN HIGH PRESSURE TO THE EAST AND LOW PRESSURE TO THE WEST. VFR CONDITIONS AND LIGHT SOUTH TO SOUTHEAST WINDS CAN BE EXPECTED TONIGHT INTO THURSDAY. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE OVER THE WESTERN TAF SITES LATE TONIGHT. MVFR CIGS/VSBY IS STILL POSSIBLE EARLY THURSDAY MORNING AROUND KPIR. VFR CONDITIONS FOR ALL TERMINALS CAN BE EXPECTED DURING THE DAYTIME THURSDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...VIPOND SHORT TERM...TMT LONG TERM...WISE AVIATION...VIPOND WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
730 PM CDT WED AUG 14 2013 .UPDATE... SEE UPDATED AVIATION DISCUSSION BELOW. && .PREVIOUS DISCUSSION... .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT PRETTY QUIET ACROSS THE CWA THIS AFTERNOON BUT WILL BE WATCHING THE WESTERN CWA OVER THE NEXT FEW HOURS FOR THE POTENTIAL FOR A FEW ISOLD THUNDERSHOWERS AS SHORTWAVE ENERGY APPROACHES FROM THE MIDWEST. BEST SUPPORT DOES NOT ARRIVE UNTIL LATER THIS EVENING...BUT DAYTIME HEATING ACROSS THE WESTERN CWA HAS ALLOWED MLCAPE TO APPROACH 1000 J/KG. SHEAR IS LACKING ONCE AGAIN AS HAS BEEN THE CASE THE PAST FEW DAYS. CURRENTLY SEEING A CONGESTED CU FIELD ACROSS NORTH CENTRAL SD WITH RADAR ECHOES JUST BEGINNING TO INCREASE OVER CORSON COUNTY. HRRR ACTUALLY PICKING UP ON THIS AND SHOWING A FEW POPCORN TYPE LIGHT SHOWERS OR MAYBE A MODERATE THUNDERSHOWER THROUGH LATE AFTERNOON. WILL MAINTAIN SLIGHT CHANCE POPS FOR THE WESTERN CWA THROUGH THE AFTERNOON. MAIN SHORTWAVE ENERGY APPROACHES THE REGION LATER THIS EVENING...BUT MODELS NOT TOO IMPRESSED WITH THIS FOR OUR CWA. 12Z NSSL WRF SHOWS A LINE OF SHOWERS AND STORMS MOVING INTO WESTERN SD LATER THIS EVENING BUT DIES OUT AS ITS ENTERING THE WESTERN CWA. WILL MAINTAIN SMALL POPS OVERNIGHT AS WELL...BUT HAVE TRIMMED THINGS DOWN TO DRY FOR THE EASTERN CWA AS THERE JUST DOESNT SEEM TO BE ANY SUPPORT FOR PRECIP. THERE REALLY IS NO LOW LEVEL JET TO SPEAK OF OVERNIGHT EITHER. WEAK SHORTWAVE ENERGY MOVES SOUTHEAST OVER THE AREA ON THURSDAY BUT MODELS KEEP TRENDING DRIER AND DRIER FOR THIS...TO THE POINT NOW WHERE MOST MODELS ARENT EVEN SHOWING ANY PRECIP FOR THE AREA. HAVE SCALED BACK POPS QUITE A BIT...GOING DRY IN PLACES BUT KEEPING A SLIGHT CHANCE GOING FOR MOST PLACES. AFTER THURSDAY...THE WARM UP BEGINS AS UPPER RIDGING BUILDS OVER THE HIGH PLAINS AND DAKOTAS. .LONG TERM...SATURDAY THROUGH WEDNESDAY MAIN CHALLENGE IN THE LONG TERM WILL BE PRECIP CHANCES UNDER THE DOMINANT UPPER RIDGE. MODELS ARE NOT IN GOOD AGREEMENT TODAY IN THE EXTENDED. TOSSED OUT THE GEM AS IT IS THE ONLY MODEL SHOWING A DEVELOPING TROPICAL SYSTEM IN THE GULF THIS WEEKEND. THIS MAY CONTAMINATE QPF AND PRESSURE FIELDS ALL THE WAY NORTH INTO THE DAKOTAS. GFS AND ECMWF ARE BOTH FLIP FLOPPING WITH MOISTURE FIELDS THOUGH SFC PRESSURE PROGS ARE SIMILAR. BOTH MODELS SHOW TWO TROFS MOVING ACROSS THE DAKOTAS...ONE SUNDAY NIGHT/MONDAY AND ANOTHER TUESDAY NIGHT/WEDNESDAY. HOWEVER THE GFS IS WET FOR THE FIRST AND DRY FOR THE SECOND WHILE THE ECMWF IS OPPOSITE. STUCK WITH ALLBLEND POPS SUNDAY NIGHT/MONDAY AS 30S/40S SEEM REASONABLE AT THIS POINT. WENT DRIER THAN ALLBLEND FOR THE END OF THE PERIOD BASED ON INTER OFFICE COLLABORATION. TEMPERATURES SHOULD BE ON THE RISE THROUGH THE PERIOD WITH HIGHS IN THE UPPER 80S TO LOWER 90S EXPECTED. && .AVIATION... 00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS FAIRLY TRANQUIL CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE LOCAL TERMINALS AS THE REGION REMAINS BETWEEN HIGH PRESSURE TO THE EAST AND LOW PRESSURE TO THE WEST. VFR CONDITIONS AND LIGHT SOUTH TO SOUTHEAST WINDS CAN BE EXPECTED TONIGHT INTO THURSDAY. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE OVER THE WESTERN TAF SITES LATE TONIGHT. MVFR CIGS/VSBY IS STILL POSSIBLE EARLY THURSDAY MORNING AROUND KPIR. VFR CONDITIONS FOR ALL TERMINALS CAN BE EXPECTED DURING THE DAYTIME THURSDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...VIPOND SHORT TERM...TMT LONG TERM...WISE AVIATION...VIPOND WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
203 PM MDT TUE AUG 13 2013 .SHORT TERM...THIS EVENING THROUGH WEDNESDAY NIGHT ISSUED AT 201 PM MDT TUE AUG 13 2013 WATER VAPOR IMAGERY CONTINUES TO SHOW BLOCKING PATTERN ACROSS THE CONUS WITH UPPER RIDGING CENTERED ACROSS THE ROCKIES INTO THE HIGH PLAINS. SURFACE ANALYSIS SHOWS HIGH PRESSURE ACROSS THE DAKOTAS WITH THE FRONTAL BOUNDARY STRETCHED ACROSS CENTRAL SD. STORMS HAVE STARTED FIRING ACROSS NORTHWEST SD INTO THE BLACK HILLS AREA WITH A COUPLE SEVERE AT THIS TIME. STORMS WILL CONTINUE TO DEVELOP OVER THE NEXT FEW HOURS OVER THE AREA. THE BEST INSTABILITY IS ACROSS SE MONTANA THROUGH WESTERN SD WITH MLCAPE OF 2000 TO 2500 J/KG. LOW LEVEL SHEAR IS OVERALL WEAK...BUT IS BEST ACROSS NW SD. WITH DEEP INSTABILITY...ENOUGH SHEAR FOR CONTINUED SUPERCELL DEVELOPMENT INTO THIS EVENING...AND PERHAPS AN ISOLATED SEVERE STORM THROUGH THE OVERNIGHT HOURS. LARGE HAIL AND DAMAGING WINDS ARE THE MAIN THREATS TODAY AND TONIGHT. STORMS WILL AGAIN BE SLOW MOVING AND HAVE THE POTENTIAL FOR PRODUCING LOCALLY HEAVY RAINFALL. LITTLE CHANGE TO THE OVERALL PATTERN TOMORROW WITH UPPER RIDGING AXIS WEST OF THE AREA. LINGERING STORMS ARE POSSIBLE ACROSS THE AREA TOMORROW MORNING...BUT A REDEVELOPMENT OF STORMS ARE EXPECTED IN THE AFTERNOON. INSTABILITY IS PROGGED TO BE WEAKER TOMORROW...WITH RELATIVELY WEAK SHEAR CONTINUING. SUBTLE WAVES WILL HELP TRIGGER CONVECTION...BUT ASIDE FOR AN ISOLATED SEVERE STORM OR TWO...SEVERE WEATHER IS NOT EXPECTED. WEAK STEERING WINDS WILL AGAIN RESULT IN SLOW STORM MOTION. && .LONG TERM...THURSDAY THROUGH TUESDAY ISSUED AT 201 PM MDT TUE AUG 13 2013 MEAN WESTERN NOAM RIDGING TO REMAIN IN THE PERIOD...WITH DOWNSTREAM MEAN NEGATIVE HEIGHT ANOMALIES LINGERING BUT WEAKENING IN THE EASTERN NOAM. PATTERN CHANGE WILL OCCUR AS THE NE PAC PERSISTENT UPPER TROUGH IS FORECAST TO CYCLE...WITH UPPER RIDGING EXPECTED OVER THE NORTHERN PLAINS FRIDAY THROUGH MUCH OF NEXT WEEK. MID LEVEL TROUGH AND ASSOCIATED SFC REFLECTION STILL ON TRACK TO PROGRESS THROUGH THE REGION SUNDAY/SUNDAY NIGHT...WITH CONTINUED CHANCES FOR SHRA/TS THEN. OTHERWISE...HAVE KEPT THE REMAINDER OF THE PERIOD DRY...SAVE FOR THIS THUR WHEN THE LAST IN A SERIES OF DISTURBANCES WILL EXIT THE REGION. FAIRLY WARM TEMPS EXPECTED AS THE UPPER RIDGE TILTS OVER THE REGION SAT-SUN...THEN AGAIN TUESDAY WITH A RESURGENCE OF THE WESTERN NOAM RIDGE. THERE IS SOME LINGERING UNCERTAINTY TO HOW FAR EAST AND NORTH THE UPPER RIDGE WILL BUILD...WHICH WILL HAVE A LARGE IMPACT OF LOCAL TEMPS/MOISTURE. DOWNSTREAM DEVELOPMENTS WILL ALSO HAVE AN EFFECT ON THIS PROCESS...MAINLY BEING IF THE PERSISTENT EASTERN NOAM TROUGH RETURNS...HINTED AT IN THE ECMWF NEXT WEEK BEYOND THE CURRENT FORECAST PERIOD. BEFORE THE NEXT PATTERN IS ESTABLISHED...SLIGHTLY PROGRESSIVE FLOW/WARMER TEMPS/AND DECREASING LL MOISTURE LOOKS PROBABLE IN THE PERIOD. HAVE OPTED TO SIDE ON THE WARMER SIDE OF MIDDLE GUIDANCE NUMBERS GIVEN THE DIRER PATTERN...WHICH LOOKS TO REMAIN THROUGH MUCH OF THE PERIOD ATTM. && .AVIATION...FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON ISSUED AT 201 PM MDT TUE AUG 13 2013 VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE PERIOD SAVE IN AN NEAR SCT TS THIS AFTERNOON AND TONIGHT. MVFR/IFR CIGS WILL BE POSSIBLE ONCE AGAIN TOWARD DAWN OVER THE EASTERN FA...WITH EASTERLY FLOW POSSIBLY PUSHING STRATUS BACK INTO THE EASTERN BH FOOTHILLS TUE MORNING. DID HINT AT THIS IN THE RAP TAF. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ SHORT TERM...13 LONG TERM...JC AVIATION...JC
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
346 PM CDT TUE AUG 13 2013 .DISCUSSION... MUCH CONVECTIVE ACTIVITY OCCURRING ALONG A NORTHERN TEXAS (QUASI) STATIONARY BOUNDARY THAT MAY EVENTUAL IMPACT OUR NORTH(EAST)ERN COUNTIES WITHIN THE NEXT 4 TO 6 HOURS. A VERY HEATED AND MOIST DOWNSTREAM AIR MASS FOR THIS STATIONARY BOUNDARY...OR SUBSEQUENT CONVECTIVE OUTFLOW...TO WORK WITH IN THE COMING 24-36 HOURS. THERE IS STILL SUBSIDENCE TO WORK WITH AS THERE HAVE BEEN RECENT HEIGHT RISES AND A FEW DEGREES OF WARMTH AT THE 85-7H LEVELS...BUT THE UPPER LEVELS REMAIN FAIRLY DIFFULENT AS EAST TEXAS FALLS WITHIN A (RELATIVELY) MILD MID-UPPER LEVEL HEIGHT WEAKNESS BETWEEN DESERT SOUTHWEST AND FLORIDA-CENTERED RIDGING. ALL OF THE THERMODYNAMIC INDICES ARE THERE TO SUPPORT RETURNING SCATTERED SHOWERS AND STORMS BEGINNING AS EARLY AS MID-WEDNESDAY MORNING. K-INDICES AROUND 40...L.I. IN THE -5 REALM...AND ABOVE 1 K J/KG CAPES FROM THE GFS/NAM PROGS OVER THE NORTHERN CWA INCREASE THE SHOWER/STORM PROBABILITY. YES...THERE WILL BE SOME SUBSIDENCE TO DEAL WITH...BUT WITH A CONSISTENT RUN-TO-RUN THEME OF INTRODUCING WEAK LOWER MS VALLEY TROUGHING (AND WITNESSING WHAT IS ONGOING ACROSS DFW`S FA)...HAD TO BITE ON THE LIKELY SIDE OF POPS. GREATER THAN 2 INCH PWATS WILL POOL ALONG `A` BOUNDARY...WHETHER THAT BE MORE OF A SYNOPTIC OR A SERIES OF MESOSCALE (UPSTREAM OUTFLOW) BOUNDARIES. OTHER THAN SUBSIDENCE AS A RAIN INHIBITER...THE ONLY OTHER NEGATIVE TO MORE WIDESPREAD COVERAGE WOULD BE THAT THE REGION DOES FALL INTO MORE OF A RR QUAD OF THE JET (ALTHOUGH 25-3H FLOW REMAINS DIFFULENT). NEEDLESS TO SAY...BUT WHAT EVOLVES TOMORROW WILL DRIVE THURSDAY`S FORECAST. SINCE THE FORECAST IS MORE WET TOMORROW...ANTICIPATING THAT THERE WILL BE SOME RESIDUAL BOUNDARIES LEFT OVER IN THE MIX. A LESS-WORKED OVER SOUTHERN CWA AIR MASS...WITH POSSIBLE LEFT-OVER WEDNESDAY SMALL SCALE BOUNDARIES (AND MAYBE SOME ASSISTANCE FROM THE LOCAL BREEZE?) WILL KEEP CHANCE POPS IN PLAY CLOSER TO THE COAST THURSDAY INTO FRIDAY. A MUCH DRIER AIR MASS FILTERING IN ALONG THE WESTERN LEG OF A EASTERN-BASED MID-UPPER TROUGH AXIS WILL COME OVER US DURING THE WEEKEND...SUBSTANTIALLY LOWERING RAIN CHANCES. THE EXTENDED SHOWS NOT MUCH IN THE WAY OF ANY DISCERNIBLE WEATHER FEATURE THAT WILL INCREASE RAIN CHANCES BEYOND THE LOCAL SCALE BREEZES. IF ANYTHING...RIDGING TAKES MORE OF A GRIP AND MID-LEVELS ARE MODELED TO WARM BACK UP INTO THE LOWER 20S BY THIS TIME NEXT WEEK. AS HAS BEEN THE CASE THESE PAST FEW DAYS...THE BAY OF CAMPECHE HAS REMAINED SOMEWHAT ACTIVE...WITH THE NWP SUITE MAINTAINING LOWERING PRESSURES AND A GREATER THAN 2 INCH PW AIR MASS. CENTRAL GULF SHEAR REMAINS STOUT (30 KTS BETWEEN THE TWO UPPER RIDGES) SO NOT TOO WORRIED WITH ANY CLOSED-OFF CIRCULATION MOVING TOO FAR NORTH OF THE BAY. 31 && .MARINE... A RELATIVELY FLAT PRESSURE GRADIENT ACROSS THE COASTAL WATERS WILL KEEP MAINLY LIGHT ONSHORE WINDS AND LOW SEAS IN PLACE THROUGH THE MIDDLE OF THE WEEK. A WEAK FRONT IS STILL EXPECTED TO APPROACH THE COAST FROM THE NORTH AND NORTHEAST ON WEDNESDAY NIGHT AND THURSDAY. THIS BOUNDARY COULD BRING THE AREA A BRIEF PERIOD OF OFFSHORE WINDS. A WEAK TROUGH OF LOW PRESSURE OVER THE CENTRAL GULF WILL MAINTAIN E-NE WINDS THROUGH SUNDAY. 43 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 76 94 73 95 75 / 20 60 20 20 10 HOUSTON (IAH) 78 96 76 93 74 / 20 60 30 40 20 GALVESTON (GLS) 83 91 81 90 81 / 10 40 40 30 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...31
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1230 PM CDT TUE AUG 13 2013 .UPDATE... LATE MORNING SFC ANALYSIS SHOWS A WEAK OUTFLOW BOUNDARY THAT HAD MOVED TO THE SRN EDGE OF THE FCST AREA EARLIER HAD NOW BEGUN TO DISSIPATE WITH LIGHT SOUTH WINDS BEGINNING TO OVERTAKE THE SRN SOUTH PLAINS. MEANWHILE...ANOTHER WEAK BOUNDARY WAS BEGINNING TO SHARPEN ACROSS THE NRN PANHANDLE...AND IT IS THIS BOUNDARY THAT THE NAM AND RAP SEEM TO BE KEYING ON FOR AFTN THUNDERSTORM DEVELOPMENT. 12Z MODEL RUN WANTS TO SHIFT THIS BOUNDARY A BIT FURTHER SWD THAN PREVIOUS FCST AND AS A RESULT HAVE SHIFTED AXIS OF HIGHER POPS FOR THE 18Z-00Z TIME FRAME SWD AS WELL. OTHER CHANGES TO AFTN WERE EVEN MORE MINOR...MAINLY ADJUSTING FOR TRENDS IN DEW POINT AND WIND. HAVE LEFT EVENING FCST ALONE FOR NOW. MAY ALSO NEED TO SHIFT HIGHER POPS SWD THERE...BUT WOULD LIKE TO SEE THE WHITES OF ITS EYES IN RELATION TO EXPECTED INITIATION ZONE BEFORE MAKING CHANGES. SECONDARY PRECIP MAY COME WITH HIGH TERRAIN STORMS FROM NERN NM SURGING SEWD INTO MOIST UPSLOPE FLOW AIDED BY ABOUT 30 KT FLOW AT 500 MB. ATTM HIGH CHANCE TO LIKELY POPS FAVORING NRN ZONES STILL APPROPRIATE WITH REEVALUATION FOR THE AFTN PACKAGE. && .AVIATION... WEAK SFC BOUNDARY SHOULD FOCUS SCATTERED CONVECTION LATE AFTN EARLY EVENING PROBABLY IN A BAND NEAR BOTH TERMINALS...POSSIBLY BETWEEN THE TWO...BUT PROBABLY HIGH ENOUGH CONFIDENCE TO INSERT A TEMPO MENTION. NAM MODEL SEEMS TO BE OVERPLAYING POTENTIAL FOR MVFR CIGS LATE TONIGHT. THIS IS A BIAS OF THAT MODEL AND FOR NOW WILL LEAN TOWARD THE MORE OPTIMISTIC GFS. && .PREV DISCUSSION... /ISSUED 639 AM CDT TUE AUG 13 2013/ AVIATION... A COLD FRONT MOVING THROUGH THE AREA WILL BRING A N-NE WIND SHIFT TO KLBB BY ABOUT 13Z...FOLLOWED BY PREVAILING E-NE WINDS AT BOTH TERMINALS THROUGH THE REMAINDER OF THE FCST. SCATTERED SHOWERS AND THUNDERSTORMS MAY AFFECT EITHER/BOTH TERMINALS THIS AFTERNOON AND EVENING AND WE HAVE A PROB30 MENTION AT BOTH. THE SHOWER ACTIVITY MAY CONTINUE OVERNIGHT BUT WITH LOW CONFIDENCE IN THE PARTICULARS. ALSO...THERE IS SOME INDICATION THAT LOW CEILINGS NEAR OR BELOW 2000 FT MAY DEVELOP AT EITHER TERMINAL...MORE LIKELY AT KCDS. WE WILL LEAVE MENTION OUT OF TAF FOR NOW UNTIL THERE IS A STRONGER INDICATION. PREV DISCUSSION... /ISSUED 419 AM CDT TUE AUG 13 2013/ SHORT TERM... INITIAL OUTFLOW BOUNDARY MOVED THROUGH MOST OF THE AREA LAST NIGHT WITH WEAK EASTERLY WINDS NOTED ACROSS ALL BUT THE SW SPLNS...WHERE WINDS REMAINED SOUTHERLY. WE/VE SEEN SOME MORNING SHOWER ACTIVITY CROP UP JUST WEST OF THE STATE LINE AS WE CONTINUE TO SEE SOME WEAK UPPER-AIR RIPPLES ROTATE AROUND A VERY FLAT RIDGE CENTERED OVER SW TX. FARTHER TO THE NORTH...A W-E BAND OF MORE WIDESPREAD SHOWERS AND THUNDERSTORMS STRETCHED ACROSS THE NRN TX PANHANDLE WITH A WELL-DEFINED OUTFLOW/COLD FRONT BOUNDARY MOVING SOUTH...APPROACHING KAMA AT 3 AM. THIS BOUNDARY SHOULD MOVE INTO OUR NRN ZONES EARLY THIS MORNING...AND POSSIBLY FARTHER SOUTH BEFORE LOSING MOMENTUM. SURFACE WINDS WILL BECOME FAIRLY LIGHT ACROSS THE AREA TODAY...LIKELY WITH A SMALL NORTH TO EAST COMPONENT. THIS SHOULD MAINTAIN HEALTHY MOISTURE IN PLACE IN THE LOW-LEVELS. ALOFT...WATER VAPOR IMAGERY THIS MORNING SHOWS A SHORTWAVE LIFTING NORTH ACROSS THE GREAT BASIN...ANOTHER SWINGING SOUTH THROUGH THE DAKOTAS...WITH CONVOLUTED FLOW IN-BETWEEN THESE TWO SYSTEMS FROM THE SRN ROCKIES INTO THE HIGH PLAINS. AN UPPER-LVL JET WILL ADVANCE INTO SRN CO/KS TODAY...WITH A BELT OF 30+ KT MID-LVL WINDS DEVELOPING ACROSS NE NM TO WRN OKLA THIS AFTERNOON...AND SPREADING INTO THE NRN SPLNS TO RED RIVER VALLEY TONIGHT. LIFT WITH THE JET WILL COUPLE WITH LOW-LVL LIFT IN THE FRONT/OUTFLOW ZONE AND A MODERATELY UNSTABLE AIRMASS TO SUPPORT CONVECTIVE CHANCES THROUGH THE DAY AND ON INTO THE NIGHT. HIGH-RES GUIDANCE SUGGESTS THAT THE ACTIVITY IN THE PANHANDLE WILL SAG SOUTH INTO OUR NRN ZONES THIS MORNING AND WEAKEN. THEN THIS AFTERNOON...WE SHOULD SEE SCATTERED CONVECTIVE DEVELOPMENT PRIMARILY ACROSS THE NW PORTIONS OF THE SPLNS AND SWRN TX PANHANDLE...ALTHOUGH WE CAN/T RULE OUT DEVELOPMENT ALMOST ANYWHERE. STORMS WILL GENERALLY MOVE EAST AND WILL TAP INTO MLCAPES RUNNING 1000 TO 2000 J/KG AND 0-6 KM BULK SHEAR OF 30 KTS SOUTH TO 40+ KT NORTH. THIS ENVIRONMENT WILL SUPPORT SOME SEVERE STORM POTENTIAL /MAINLY DAMAGING WIND GUSTS/ THIS THREAT WILL BE HIGHER ACROSS THE NRN ZONES WHERE THE SHEAR WILL BE GREATER...BUT WE WILL HAVE TO MONITOR JUST WHERE THE OUTFLOW BOUNDARY ACTUALLY SETS UP TO ENHANCE LOW-LVL CONVERGENCE AND LIFT. ALSO...STORM CELLS POSSIBLY TRAINING ON THE COLD SIDE OF THE BOUNDARY COULD LEAD TO SOME LOCALLY HEAVY RAIN POTENTIAL THIS EVENING. AS WE HEAD INTO THE OVERNIGHT HOURS...THE FORECAST CONFIDENCE DECREASES AS BEST UPPER-LEVEL LIFT WILL REMAIN POSITIONED ACROSS THE NORTH...BUT BEST LOW-LVL FOCUS WILL KEEP SHIFTING SOUTH...WITH THE FRONT MOVING ON INTO THE PERMIAN BASIN BY EARLY WED MORNING. THE BULK OF GUIDANCE KEEPS THE HIGHEST RAIN CHANCES PINNED ACROSS THE NORTH. OVERALL COVERAGE AND STRENGTH OF ACTIVITY IS EXPECTED TO WANE AFTER MIDNIGHT...ALTHOUGH WE WILL HAVE TO WATCH BACK TO THE WEST WHERE A OVERNIGHT COMPLEX MAY BEGIN TO FORM NEAR THE STATE LINE WHERE LIFT FROM NEXT SHORTWAVE STARTS TO IMPINGE ON POST-FRONTAL UPSLOPE. LONG TERM... AN UNSETTLED STRETCH OF WEATHER WILL KICK OFF THE EXTENDED FORECAST THANKS TO A PERIOD OF NORTHWESTERLY FLOW ALOFT AND A FRONTAL BOUNDARY IN/NEAR THE AREA. HOWEVER...THE DEVIL IS IN THE DETAILS WITH MUCH UNCERTAINTY IN THE SPATIAL AND TEMPORAL DISTRIBUTION OF THE BEST SHOWER/STORM CHANCES RESULTING FROM UNKNOWNS REGARDING THE EXACT FRONTAL POSITION AND TIMING OF SUBTLE SHORTWAVES MOVING THROUGH THE FLOW ALOFT. NORTHWESTERLY MID-LEVEL FLOW WILL BEGIN TO TAKE SHAPE ON WEDNESDAY AS AN UPPER RIDGE AMPLIFIES OVER THE ROCKIES DOWNSTREAM OF A LARGE VORTEX CENTERED OFF THE COAST OF BRITISH COLUMBIA. WEST TEXAS WILL BE POSITIONED BETWEEN THE RIDGE AND LARGE-SCALE TROUGHING ACROSS THE EASTERN PORTION OF THE CONTINENT. AT THE SFC...A FRONTAL BOUNDARY IS PROGGED TO SETTLE SOUTHWARD THROUGH MOST IF NOT THE ENTIRE CWA EARLY WEDNESDAY...WITH RICH POST-FRONTAL MOISTURE ADVECTING IN ON UPSLOPE WINDS. THIS MOIST ENVIRONMENT WILL READILY SUPPORT PRECIPITATION AND EFFICIENT RAINFALL RATES GIVEN ANY SUBTLE FORCING FOR ASCENT. INITIALLY THE FRONTAL FORCING AND PERHAPS WEAK UPPER SUPPORT WILL KEEP DECENT RAIN CHANCES GOING ON WEDNESDAY...WITH ADDITIONAL CONVECTION FOCUSED ALONG AND BEHIND THE FRONT AS DAYTIME HEATING PEAKS AND A POSSIBLE WEAK SHORTWAVE TROUGH APPROACHES. ONE QUESTION MARK IS HOW MUCH HEATING CAN DEVELOP WEDNESDAY AFTERNOON WITH THE NAM SUGGESTING LOW CLOUDS MAY HOLD TOUGH MUCH OF THE DAY AND LIMIT POTENTIAL INSTABILITY. THE ECMWF AND GFS ARE MORE OPTIMISTIC AND PROJECT SBCAPES CLIMBING TO NEAR OR IN EXCESS OF 1500 J/KG. IF THE STRONGER INSTABILITY IS REALIZED IT COULD BRING THE POTENTIAL FOR A FEW STRONG TO SEVERE STORMS AS 0-6 KM SHEAR CLIMBS TO AROUND 35 KNOTS. WE WILL ALSO LOOK FOR THE POSSIBILITY OF A MCS ROLLING IN LATE FROM THE NORTH...THOUGH THE COOLER AND MORE STABLE NAM SOLUTION DOES NOT SUPPORT THIS. FOR NOW...HAVE MADE ONLY MINOR ADJUSTMENTS TO THE POP/WX GRIDS...MAINTAINING A 30-40 PERCENT CHANCE OF STORMS WEDNESDAY AND WEDNESDAY NIGHT. THE OVERALL SETUP WILL NOT CHANGE MUCH THURSDAY...THOUGH THE FRONTAL ZONE MAY RETREAT A BIT...SO THUNDER CHANCES WILL CONTINUE WITH NWP CURRENTLY SUGGESTING ANOTHER SHORTWAVE WILL APPROACH FROM THE NORTHWEST LATE KEEPING STORM CHANCES GOING LATE INTO THE NIGHT. THE UPPER FLOW WILL TURN MORE NORTHERLY ON FRIDAY AS THE WESTERN RIDGE FURTHER AMPLIFIES AND BEGINS TO EDGE EASTWARD. THIS WILL REDUCE THE CHANCE THAT CONVECTION ORIGINATING OVER THE HIGHER ELEVATION OF NM AND CO CAN MAKE ITS WAY TO THE SOUTH PLAINS...BUT WITH THE RESIDUAL FRONTAL BOUNDARY STILL IN THE AREA AND A SHORTWAVE GRAZING WEST TEXAS FROM THE EAST...HAVE MAINTAINED LOW STORM CHANCES. DRIER AIR WILL GRADUALLY ADVECT IN ALOFT OVER THE WEEKEND AS THE UPPER RIDGE BENDS FURTHER EASTWARD AND A DRYING TREND WILL LIKELY ENSUE. THIS RIDGE WILL GRADUALLY BREAKDOWN LATE WEEKEND INTO EARLY NEXT WEEK AS A TROUGH EMERGES FROM THE CENTRAL/NORTHERN ROCKIES. THIS COULD BEND THE MONSOON MOISTURE EASTWARD...PERHAPS REJUVENATING STORM CHANCES. REGARDING TEMPERATURES...TENDED TO FAVOR THE COOL SIDE OF GUIDANCE GIVEN THE EXPECTED CLOUD COVER AND RAIN IN THE AREA MID TO LATE WEEK. TEMPERATURES WILL GRADUALLY TREND UPWARD BY THIS WEEKEND AS THE UPPER RIDGE BENDS OVER AND SOUTHERLY LOW-LEVEL FLOW RETURNS TO WEST TEXAS. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 85 62 84 61 86 / 40 50 40 40 30 TULIA 86 64 82 63 84 / 40 50 40 40 30 PLAINVIEW 89 65 81 64 84 / 30 40 40 40 30 LEVELLAND 91 66 84 65 88 / 30 30 40 40 30 LUBBOCK 91 68 83 65 86 / 30 30 40 40 30 DENVER CITY 94 66 88 65 91 / 20 20 40 30 30 BROWNFIELD 93 68 86 65 90 / 20 20 40 40 30 CHILDRESS 89 68 85 68 87 / 40 60 40 40 30 SPUR 93 70 86 68 89 / 30 30 40 40 30 ASPERMONT 95 72 89 69 90 / 20 30 40 40 30 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1200 AM CDT TUE AUG 13 2013 .AVIATION... VFR CONDITIONS EXPECTED THROUGH AT LEAST 18Z TUESDAY...WITH THE POTENTIAL FOR TSRA TOMORROW AFTERNOON FIRST AT CDS...AND LATER AT LBB. THESE STORMS WILL BE MADE POSSIBLE IN PART BY A PASSING COLD FRONT...THE TIMING OF WHICH IS STILL RELATIVELY UNCERTAIN. CONFIDENCE IS HIGHER IN TSRA AT CDS...WITH LOWER PROBABILITIES AT LBB OWING TO THE UNCERTAINTIES RELATED TO THE TIMING OF THE FRONTAL PASSAGE. PERIODIC MVFR CONDITIONS WILL BE POSSIBLE IF STORMS DRIFT OVER EITHER TERMINAL...BUT OPTED TO LEAVE OUT EXPLICIT MENTION UNTIL THE TIMING OF THUNDERSTORM ACTIVITY BECOMES MORE CLEAR. && PREV DISCUSSION... /ISSUED 346 PM CDT MON AUG 12 2013/ SHORT TERM... WEATHER PATTERN OVER THE NEXT DAY WILL BE LARGELY DRIVEN BY ELONGATED UPPER HIGH ALONG THE GULF COAST WITH A RIDGE EXTENDING FROM AROUND THESE PARTS UP TO THE CANADIAN PRAIRIES. MONSOON MOISTURE CONTINUES TO WRAP AROUND THE PERIPHERY OF THE HIGH CENTER GENERALLY STREAMING FROM NORTHEASTERN NEW MEXICO TO THE TEXAS PANHANDLE AND BEYOND. AREA OF SYNOPTIC SCALE LIFT IS EVIDENT TO OUR NORTH AND NORTHWEST AND THIS IS WHERE TSTM ACTIVITY INITIATED. HOWEVER...TO THE SOUTH...ACROSS OUR REGION...AXIS OF THETA-E MAXIMA HAS HELPED INITIATE ISOLATED CONVECTION FROM DORA TO MEMPHIS. GIVEN THAT THESE SHOWERS DEVELOPED BY 2PM...INDICATIONS ARE THAT THE ATMOSPHERE IS SUFFICIENTLY MOIST TO SUPPORT AT LEAST SCATTERED STORMS FOR MUCH OF THE AFTERNOON INTO THE EVENING HOURS...FAVORING THE NORTHERN HALF OF THE AREA. AN INTERESTING SOLUTION IS EVIDENT IN THE HRRR WITH CONVECTION FORMING OUT NORTHWEST OF LUBBOCK AND MOVING SLOWLY THIS WAY...BUT PERHAPS NOT REACHING THE CITY. GIVEN THAT THIS SOLUTION IS SOMEWHAT REPRESENTED IN LOCATION / THOUGH NOT COVERAGE / HAVE EXPANDED POPS SOUTHWARD THIS EVENING. LIKE THE PAST SEVERAL NIGHTS...LOW-END SEVERE STORMS WILL BE POSSIBLE WITH CONDITIONS WANING TUESDAY MORNING FOR A WHILE. A BACK DOOR FRONT IS INDICATED BY GUIDANCE AND WITH THE ALREADY PLENTIFUL CONVECTION ACROSS THE PANHANDLE...PREFER THE QUICKER SOLUTION AND AS SUCH HAVE BROUGHT THE BOUNDARY...AND ASSOCIATED INCREASED RAIN CHANCES...INTO OUR CWFA DURING THE AFTERNOON ON TUESDAY. LONG TERM... MID-LEVEL PATTERN WILL CONTINUE TO AMPLIFY INTO THE EXTENDED WITH STRONGER NW FLOW AND DEEP LAYER SHEAR ACROSS THE SOUTH PLAINS TUE PM INTO WED IN THE WAKE OF THE FRONTAL BOUNDARY. THIS SCENARIO SHOULD SUPPORT CONTINUED WIDESPREAD PRECIP CHANCES AS MOST MODELS SUPPORT SOME Q-G LIFT ALONG WITH FRONTOGENETICAL FORCING CENTERED OVER ERN NM INTO THE WRN SOUTH PLAINS. FAVORABLE 700MB THETA-E AXIS ALSO REMAINS IN PLACE WITH PWATS INCREASING THROUGH THE FIRST COUPLE OF DAYS OF THE EXTENDED PERIOD AS WELL. ONE LIMITING FACTOR FOR CONSIDERATION FOR INCREASED COVERAGE WITH TIME IS THE INSTABILITY DURING THE DAY WED. EXPECT CONSIDERABLE CLOUDINESS AND UPSLOPE FLOW TO INHIBIT WARMING AND SUBSTANTIAL CAPE HOWEVER DEEPLY MOIST ATMOSPHERE SHOULD AID DEVELOPMENT LOCALLY. ADDITIONAL HEATING ACROSS EASTERN NM COUPLED WITH AMPLE SHEAR SHOULD HELP SOME ACTIVITY TO ORGANIZE AND MOVE ACROSS THE WESTERN HALF OF THE AREA AGAIN LATE EVENING AND OVERNIGHT WED NIGHT. SUBTLE SHORTWV ACTIVITY TRAVERSING THE NW FLOW WILL HELP SUSTAIN AFTN STORMS THU IN CONTINUED LIGHT UPSLOPE FLOW. ONCE AGAIN UNCAPPED ATMOSPHERE WILL ALLOW SHOWERS TO FORM EARLY AND PREVENT THINGS FROM BECOMING TOO UNSTABLE WITH SEVERE THREAT LIMITED OUTSIDE OF SOME HEAVY RAINERS. FLOW TURNS MORE NRLY ON FRI AS RIDGE BUILDS FROM 4 CORNERS INTO MONTANA. GFS AND EURO BOTH SUPPORT UPPER LOW DROPPING INTO THE MO VALLEY ON SAT TO MAINTAIN SOME LIFT WITHIN REMNANT MOIST AXIS ON EASTERN SIDE OF THE RIDGE. WITH CONTINUED ISOLD-SCT CONVECTION POSSIBLE HAVE KEPT POPS GOING INTO THE WEEKEND WITH LITTLE TO NO OVERALL WARMING TREND. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 64 89 65 81 61 / 20 30 50 50 40 TULIA 65 89 67 80 62 / 20 30 50 50 40 PLAINVIEW 66 91 68 80 63 / 20 30 40 50 40 LEVELLAND 70 94 68 84 65 / 10 20 30 50 40 LUBBOCK 70 93 69 83 65 / 10 20 30 50 40 DENVER CITY 72 92 65 88 66 / 10 10 20 40 40 BROWNFIELD 73 94 70 86 66 / 10 10 20 50 40 CHILDRESS 72 96 69 84 67 / 20 40 50 50 30 SPUR 75 97 74 86 68 / 20 20 30 50 40 ASPERMONT 76 99 75 89 69 / 20 20 30 50 30 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99/99/16
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
754 AM EDT TUE AUG 13 2013 .SYNOPSIS... A COLD FRONT WILL PASS ACROSS THE REGION TODAY. THEN A LARGE HIGH PRESSURE SYSTEM WILL BUILD IN OVER THE OHIO VALLEY AND THE MID ATLANTIC TONIGHT AND WEDNESDAY...BRINGING SOMEWHAT COOLER AND DRIER WEATHER. THIS WILL LAST LATE INTO THE WEEK BEFORE MOISTURE STARTS TO SLOWLY RETURN BY THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 658 AM EDT TUESDAY... UPDATED POPS/WEATHER AND RAINFALL FOR NEXT FEW HOURS PER CONCENTRATED AREA OF HEAVY RAIN SHOWERS AND ISOLATED THUNDER ACROSS MT ROGERS REC AREA AND FAR NW NC. LATEST HRRR HAS REASONABLE HANDLE ON THIS AND TAKES IT ALL THE WAY INTO PIEDMONT THROUGH 13Z. THINK THIS MAY BE A LITTLE FAST AND MAY NOT SURVIVE FULLY INTACT THAT FAR EAST...BUT DID INCREASE POPS OUT OF AHEAD OF IT AND BROUGHT LIKELY INTO FOOTHILLS AND TOWARD LYH A LITTLE EARLIER. WILL NEED CONSTANT TWEAKING. RAINFALL RATES ARE FROM 2-3 INCHES PER HOUR IN STRONGER RETURNS...BUT IT IS MOVING AT ABOUT 40 MPH. ANOTHER WAVE OF ACTIVITY WILL ENTER FROM EASTERN KY THOUGH BY 800 AM...SO MANY AREAS WILL NEED TO BE WATCHED CAREFULLY FOR FLASH FLOOD POTENTIAL THROUGH AT LEAST THE MORNING HOURS. PREV DISCUSSION AS OF 440 AM EDT TUESDAY... SURFACE COOL FRONT CONTINUES TO SLOWLY MAKE ITS WAY SOUTHEASTWARD THROUGH THE OHIO VALLEY EARLY THIS MORNING WITH WAVES RIPPLING ALONG IT IN THE UPPER LEVELS. THIS IS RESULTING IN CONTINUED AREAS OF ORGANIZED BUT FAIRLY SHALLOW CONVECTION FROM UPSTATE NY AND PA...SOUTHWESTWARD ALONG THE WEST SIDE OF THE APPALACHIANS AND INTO CENTRAL KY. AREAS OF SHOWERS AND ISOLATED THUNDERSTORMS HAVE GENERALLY BEEN WEAKENING AS THEY MOVE INTO THE WESTERN PORTIONS OF OUR FCST AREA WITH WEST FLOW AND LITTLE TO NO INSTABILITY REMAINING. ONE WAVE MAY BRING A MORE ORGANIZED AREA INTO THE WEST DURING THE FRIST PART OF THE DAYLIGHT HOURS JUST AHEAD OF FRONTAL BOUNDARY. FRONT WILL THEN PUSH ACROSS DURING THE DAY...BUT AS USUAL NOT CLEANLY...WITH SOME LEE SIDE TROUGHING ALREADY EVIDENT THIS MORNING...IT MAY SHIFT INTO THE PIEDMONT THIS AFTERNOON...WITH DEEPER CONVECTION FIRING ACROSS THE EASTERN PORTIONS OF OUR AREA OR MAYBE EVEN OFF TO THE EAST BY MID TO LATE AFTERNOON. WITH TIMING OF POPS...GENERALLY FOLLOWED A BLEND OF THE 06Z RAP13 AND HIGH RES WRF-ARW FROM 00Z. DO NOT THINK THERE WILL BE MANY BREAKS IN CLOUD COVER SO INSTABILITY REMAINS WEAK TO MODEST...MAYBE 1000-1500 SFC BASED MOST AREAS...WITH UP TO 2000 J/KG IN THE EAST IF WE CAN GET A FEW BREAKS IN CLOUDS. DO NOT SEE MUCH IN THE WAY OF SEVERE WEATHER POTENTIAL GIVEN VERY MOIST AIRMASS AND NOT ESPECIALLY STEEP LAPSE RATES. LOCALLY HEAVY RAIN WILL BE MAIN CONCERN AGAIN...AND GIVEN RAINFALL LAST EVENING AND SOME CONTINUED LIGHT TO MODERATE OVERNIGHT IN FAR WEST...BIGGEST THREAT FOR ANY FLASH FLOODING REMAINS IN THE WEST...EVEN THOUGH THERE IS SOME QUESTION AS TO WHETHER ANY DEEPER CONVECTION CAN SUSTAIN ITSELF OR GET GOING DURING THE MORNING HOURS BEFORE THE FRONT PUSHES THROUGH THE MOUNTAINS. WILL KEEP THE FLASH FLOOD WATCH GOING THROUGH THE DAY...ALTHOUGH AREAS IN THE FOOTHILLS VERY MARGINAL...AND WE WILL LIKELY BE ABLE TO CANCEL EARLY AS BELIEVE ANY ORGANIZED CONVECTION AND HEAVIER RAINFALL RATES WILL SHIFT EAST BY EARLY TO MID AFTERNOON. FRONT PUSHES WELL EAST BY EARLY EVENING IF NOT SOONER..QUICKLY LOWERING THREAT OF SHWRS/STORMS ACROSS THE ENTIRE AREA BEFORE MIDNIGHT. KEPT CHC POP GOING IN EAST UNTIL MIDNIGHT...BUT MY FEELING IS THIS MAY MOVE OUT EVEN QUICKER. ALSO THERE IS LINGERING LOW LEVEL MOISTURE ON WEST SLOPES BEHIND FRONT AND MAYBE SOME SPRINKLES OR DRIZZLE IS POSSIBLE FOR A WHILE THIS EVENING BACK THERE AS WELL...SO KEPT LOW CHC POPS INTO EARLY EVENING AS WELL. TEMPERATURE WISE...AM LEANING TO COOLER MET GUIDANCE FOR HIGHS GIVEN EXPECTED CLOUD COVER...AND EVEN NUDGED DOWN A DEG OR TWO FROM THERE. ONE AREA THAT MAY END SEEING A LITTLE MORE SUN IS FAR SOUTHEAST AND IF THERE ARE MORE THAN JUST A COUPLE HOURS OF IT DURING TEH AFTERNOON THE LOW 90S TEMPS THE MAV IS ADVERTISING COULD BE REALIZED...SO WILL HAVE TO WATCH THIS. TONIGHT WE MAY SEE THE FIRST 50S IN THE WEST IN QUITE SOME TIME WITH LOWER DEW PTS MOVING IN AND SOME CLEARING. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM EDT TUESDAY... LOOKING AT MAINLY DRY CONDITIONS FOR WEDNESDAY...POSSIBLY WITH A FEW LINGERING SHOWERS ACROSS OUR NORTHWEST WIND UPSLOPE AREAS DURING THE MORNING...AS CANADIAN HIGH PRESSURE CONTINUES TO BUILD IN FROM THE UPPER MIDWEST. THIS AIRMASS WILL BRING A SIGNIFICANT COOL DOWN TO OUR AREA...WITH AFTERNOON HIGHS RANGING FROM 7 TO 9 DEGREES BELOW NORMAL FOR MID AUGUST. HIGH PRESSURE WILL SHIFT EAST DURING THE DAY...AND THEN BUILD SOUTHWARD ALONG THE EASTERN FACE OF THE APPALACHIANS WEDNESDAY NIGHT...WHICH WILL SHIFT OUR WINDS TO A NORTHEASTERLY DIRECTION. THURSDAY WILL REMAIN RELATIVELY DRY AS WELL...ALTHOUGH MAY SEE A LITTLE LIGHT RAIN ENTER THE NORTH CAROLINA MOUNTAINS AND THE MOUNTAIN EMPIRE ON THURSDAY AS WINDS AROUND THE HIGH PRESSURE WEDGE PICK UP MOISTURE FROM UPPER LEVEL DISTURBANCES RIDING ALONG THE COLD FRONT STALLED WELL TO OUR SOUTH. RAINFALL WILL REMAIN ISOLATED HOWEVER...AND WOULD NOT MAKE ANY CHANGES TO OUTDOOR PLANS AT THIS POINT. THE COOL EASTERLY FLOW WILL AGAIN KEEP TEMPERATURES SEVERAL DEGREES BELOW NORMAL...WITH MOST AREAS HOLDING IN THE 70S FOR AFTERNOON HIGHS. WILL SEE A BETTER RETURN OF MOISTURE FOR FRIDAY AS A DEEP UPPER LEVEL TROUGH MOVES INTO THE CENTRAL MISSISSIPPI RIVER VALLEY. WHILE HIGH PRESSURE WILL REMAIN IN PLACE IN THE LOW LEVELS...WINDS ALOFT ALONG THE EASTERN SEABOARD WILL BECOME INCREASINGLY SOUTHWESTERLY AS THE TROUGH AMPLIFIES. THIS UPPER FLOW WOULD BE FAVORABLE FOR CARRYING DISTURBANCES ACROSS THE CAROLINAS...WHICH WOULD POTENTIALLY TRIGGER SPOTTY SHOWERS AND THUNDERSTORMS FOR OUR AREA SOUTH OF INTERSTATE 81. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 400 AM EDT TUESDAY... AS WE PROGRESS INTO THE WEEKEND...CURRENT MODEL TRENDS OFFER A STALLED DEEPENING LOW OVER THE CENTRAL U.S. WITH THE LOW ALONG THE GULF BEING TRANSPORTED NORTHWARD ON THE EAST SIDE OF THE CENTRAL CONUS TROUGH. THIS WOULD ALLOW FOR BETTER DYNAMICS AND MOISTURE FLOW ACROSS THE REGION. THIS WILL LEAD TO BETTER CHANCE OF LIGHT TO MODERATE RAIN OVER THE AREA THROUGH SATURDAY...AND THEN BETTER CHANCES OF SHOWERS AND SOME THUNDERSTORMS BY SUNDAY. WHILE ACTIVITY MAY TAPER OFF A BIT ON MONDAY...THE CENTRAL CONUS TROUGH WOULD STILL BE TO OUR WEST...AND BE A FEATURE TO POTENTIALLY INFLUENCE OUR WEATHER PAST DAY 7. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 750 AM EDT TUESDAY... PERIODS OF IFR IN HEAVY SHOWERS AND ISOLATED THUNDERSTORMS THIS MORNING ACROSS THE WEST...WILL GIVE WAY TO MAINLY VFR CONDITIONS BY AFTERNOON BUT STILL WITH SCATTERED SHOWERS AND STORMS AND BRIEF MVFR TO IFR CONDITIONS WITH STORMS AS A COLD FRONT PUSHES THROUGH THE REGION THROUGH THE MIDDLE OF THE DAY TODAY...EXITING THE FAR SOUTHEAST BY EARLY EVENING. SOME PATCHY FOG AT DAN AND LYH THIS MORNING SHOULD ALSO IMPROVE TO VFR BY MID MORNING...YET STILL WITH BRIEF IFR CONDITIONS POSSIBLE IF A THUNDERSTORM MOVES ACROSS THE AIRPORT. KEPT THUNDER MENTIONED IN VICINITY SINCE NOT CONFIDENT IN HOW WIDESPREAD COVERAGE WILL BE OUT EAST. BY LATE TODAY THE FRONT WILL SHIFT SLOWLY SOUTHEAST AND TURN THE WINDS TO THE WNW BY AFTERNOON. BY EARLY EVENING...DRIER AIR WILL BE FILTERING IN AND LINGERING SHOWERS WILL PUSH EAST OF DAN/LYH...BY 02Z OR EARLIER. SOME LINGERING LOW LEVEL MOISTURE IN TEH FAR WEST COULD RESULT KIN IFR CIGS OVERNIGHT...AS WELL AS PATCHY IFR FOG AT VALLEY AIRPORTS...BUT BY WED VFR SHOULD DOMINATE THROUGH MOST OF THE REST OF WEEK UNDER DRY HIGHI PRESSURE. && .HYDROLOGY... AS OF 355 PM EDT MONDAY... NO CHANGES TO FLASH FLOOD WATCH. SOME AREAS RECEIVED 3"+ OVER THE MOUNTAIN EMPIRE OF SW VA...INCLUDING THE RICHLANDS AREA LAST EVENING. MORE HEAVIER DOWNPOURS ARE POSSIBLE AGAIN TODAY...MAINLY IN THE MORNING WEST AND AFTERNOON EAST. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR VAZ007-009>017-032. NC...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NCZ001>003-018-019. WV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR WVZ042>045. && $$ SYNOPSIS...SK NEAR TERM...SK SHORT TERM...NF LONG TERM...DS/NF AVIATION...SK/WP HYDROLOGY...AMS/SK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
700 AM EDT TUE AUG 13 2013 .SYNOPSIS... A COLD FRONT WILL PASS ACROSS THE REGION ON TODAY. THEN A LARGE HIGH PRESSURE SYSTEM WILL BUILD IN OVER THE OHIO VALLEY AND THE MID ATLANTIC TONIGHT AND WEDNESDAY...BRINGING SOMEWHAT COOLER AND DRIER WEATHER. THIS WILL LAST LATE INTO THE WEEK BEFORE MOISTURE STARTS TO SLOWLY RETURN BY THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 658 AM EDT TUESDAY... UPDATED POPS/WEATHER AND RAINFALL FOR NEXT FEW HOURS PER CONCENTRATED AREA OF HEAVY RAIN SHOWERS AND ISOLATED THUNDER ACROSS MT ROGERS REC AREA AND FAR NW NC. LATEST HRRR HAS REASONABLE HANDLE ON THIS AND TAKES IT ALL THE WAY INTO PIEDMONT THROUGH 13Z. THINK THIS MAY BE A LITTLE FAST AND MAY NOT SURVIVE FULLY INTACT THAT FAR EAST...BUT DID INCREASE POPS OUT OF AHEAD OF IT AND BROUGHT LIKELY INTO FOOTHILLS AND TOWARD LYH A LITTLE EARLIER. WILL NEED CONSTANT TWEAKING. RAINFALL RATES ARE FROM 2-3 INCHES PER HOUR IN STRONGER RETURNS...BUT IT IS MOVING AT ABOUT 40 MPH. ANOTHER WAVE OF ACTIVITY WILL ENTER FROM EASTERN KY THOUGH BY 800 AM...SO MANY AREAS WILL NEED TO BE WATCHED CAREFULLY FOR FLASH FLOOD POTENTIAL THROUGH AT LEAST THE MORNING HOURS. PREV DISCUSSION AS OF 440 AM EDT TUESDAY... SURFACE COOL FRONT CONTINUES TO SLOWLY MAKE ITS WAY SOUTHEASTWARD THROUGH THE OHIO VALLEY EARLY THIS MORNING WITH WAVES RIPPLING ALONG IT IN THE UPPER LEVELS. THIS IS RESULTING IN CONTINUED AREAS OF ORGANIZED BUT FAIRLY SHALLOW CONVECTION FROM UPSTATE NY AND PA...SOUTHWESTWARD ALONG THE WEST SIDE OF THE APPALACHIANS AND INTO CENTRAL KY. AREAS OF SHOWERS AND ISOLATED THUNDERSTORMS HAVE GENERALLY BEEN WEAKENING AS THEY MOVE INTO THE WESTERN PORTIONS OF OUR FCST AREA WITH WEST FLOW AND LITTLE TO NO INSTABILITY REMAINING. ONE WAVE MAY BRING A MORE ORGANIZED AREA INTO THE WEST DURING THE FRIST PART OF THE DAYLIGHT HOURS JUST AHEAD OF FRONTAL BOUNDARY. FRONT WILL THEN PUSH ACROSS DURING THE DAY...BUT AS USUAL NOT CLEANLY...WITH SOME LEE SIDE TROUGHING ALREADY EVIDENT THIS MORNING...IT MAY SHIFT INTO THE PIEDMONT THIS AFTERNOON...WITH DEEPER CONVECTION FIRING ACROSS THE EASTERN PORTIONS OF OUR AREA OR MAYBE EVEN OFF TO THE EAST BY MID TO LATE AFTERNOON. WITH TIMING OF POPS...GENERALLY FOLLOWED A BLEND OF THE 06Z RAP13 AND HIGH RES WRF-ARW FROM 00Z. DO NOT THINK THERE WILL BE MANY BREAKS IN CLOUD COVER SO INSTABILITY REMAINS WEAK TO MODEST...MAYBE 1000-1500 SFC BASED MOST AREAS...WITH UP TO 2000 J/KG IN THE EAST IF WE CAN GET A FEW BREAKS IN CLOUDS. DO NOT SEE MUCH IN THE WAY OF SEVERE WEATHER POTENTIAL GIVEN VERY MOIST AIRMASS AND NOT ESPECIALLY STEEP LAPSE RATES. LOCALLY HEAVY RAIN WILL BE MAIN CONCERN AGAIN...AND GIVEN RAINFALL LAST EVENING AND SOME CONTINUED LIGHT TO MODERATE OVERNIGHT IN FAR WEST...BIGGEST THREAT FOR ANY FLASH FLOODING REMAINS IN THE WEST...EVEN THOUGH THERE IS SOME QUESTION AS TO WHETHER ANY DEEPER CONVECTION CAN SUSTAIN ITSELF OR GET GOING DURING THE MORNING HOURS BEFORE THE FRONT PUSHES THROUGH THE MOUNTAINS. WILL KEEP THE FLASH FLOOD WATCH GOING THROUGH THE DAY...ALTHOUGH AREAS IN THE FOOTHILLS VERY MARGINAL...AND WE WILL LIKELY BE ABLE TO CANCEL EARLY AS BELIEVE ANY ORGANIZED CONVECTION AND HEAVIER RAINFALL RATES WILL SHIFT EAST BY EARLY TO MID AFTERNOON. FRONT PUSHES WELL EAST BY EARLY EVENING IF NOT SOONER..QUICKLY LOWERING THREAT OF SHWRS/STORMS ACROSS THE ENTIRE AREA BEFORE MIDNIGHT. KEPT CHC POP GOING IN EAST UNTIL MIDNIGHT...BUT MY FEELING IS THIS MAY MOVE OUT EVEN QUICKER. ALSO THERE IS LINGERING LOW LEVEL MOISTURE ON WEST SLOPES BEHIND FRONT AND MAYBE SOME SPRINKLES OR DRIZZLE IS POSSIBLE FOR A WHILE THIS EVENING BACK THERE AS WELL...SO KEPT LOW CHC POPS INTO EARLY EVENING AS WELL. TEMPERATURE WISE...AM LEANING TO COOLER MET GUIDANCE FOR HIGHS GIVEN EXPECTED CLOUD COVER...AND EVEN NUDGED DOWN A DEG OR TWO FROM THERE. ONE AREA THAT MAY END SEEING A LITTLE MORE SUN IS FAR SOUTHEAST AND IF THERE ARE MORE THAN JUST A COUPLE HOURS OF IT DURING TEH AFTERNOON THE LOW 90S TEMPS THE MAV IS ADVERTISING COULD BE REALIZED...SO WILL HAVE TO WATCH THIS. TONIGHT WE MAY SEE THE FIRST 50S IN THE WEST IN QUITE SOME TIME WITH LOWER DEW PTS MOVING IN AND SOME CLEARING. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM EDT TUESDAY... LOOKING AT MAINLY DRY CONDITIONS FOR WEDNESDAY...POSSIBLY WITH A FEW LINGERING SHOWERS ACROSS OUR NORTHWEST WIND UPSLOPE AREAS DURING THE MORNING...AS CANADIAN HIGH PRESSURE CONTINUES TO BUILD IN FROM THE UPPER MIDWEST. THIS AIRMASS WILL BRING A SIGNIFICANT COOL DOWN TO OUR AREA...WITH AFTERNOON HIGHS RANGING FROM 7 TO 9 DEGREES BELOW NORMAL FOR MID AUGUST. HIGH PRESSURE WILL SHIFT EAST DURING THE DAY...AND THEN BUILD SOUTHWARD ALONG THE EASTERN FACE OF THE APPALACHIANS WEDNESDAY NIGHT...WHICH WILL SHIFT OUR WINDS TO A NORTHEASTERLY DIRECTION. THURSDAY WILL REMAIN RELATIVELY DRY AS WELL...ALTHOUGH MAY SEE A LITTLE LIGHT RAIN ENTER THE NORTH CAROLINA MOUNTAINS AND THE MOUNTAIN EMPIRE ON THURSDAY AS WINDS AROUND THE HIGH PRESSURE WEDGE PICK UP MOISTURE FROM UPPER LEVEL DISTURBANCES RIDING ALONG THE COLD FRONT STALLED WELL TO OUR SOUTH. RAINFALL WILL REMAIN ISOLATED HOWEVER...AND WOULD NOT MAKE ANY CHANGES TO OUTDOOR PLANS AT THIS POINT. THE COOL EASTERLY FLOW WILL AGAIN KEEP TEMPERATURES SEVERAL DEGREES BELOW NORMAL...WITH MOST AREAS HOLDING IN THE 70S FOR AFTERNOON HIGHS. WILL SEE A BETTER RETURN OF MOISTURE FOR FRIDAY AS A DEEP UPPER LEVEL TROUGH MOVES INTO THE CENTRAL MISSISSIPPI RIVER VALLEY. WHILE HIGH PRESSURE WILL REMAIN IN PLACE IN THE LOW LEVELS...WINDS ALOFT ALONG THE EASTERN SEABOARD WILL BECOME INCREASINGLY SOUTHWESTERLY AS THE TROUGH AMPLIFIES. THIS UPPER FLOW WOULD BE FAVORABLE FOR CARRYING DISTURBANCES ACROSS THE CAROLINAS...WHICH WOULD POTENTIALLY TRIGGER SPOTTY SHOWERS AND THUNDERSTORMS FOR OUR AREA SOUTH OF INTERSTATE 81. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 400 AM EDT TUESDAY... AS WE PROGRESS INTO THE WEEKEND...CURRENT MODEL TRENDS OFFER A STALLED DEEPENING LOW OVER THE CENTRAL U.S. WITH THE LOW ALONG THE GULF BEING TRANSPORTED NORTHWARD ON THE EAST SIDE OF THE CENTRAL CONUS TROUGH. THIS WOULD ALLOW FOR BETTER DYNAMICS AND MOISTURE FLOW ACROSS THE REGION. THIS WILL LEAD TO BETTER CHANCE OF LIGHT TO MODERATE RAIN OVER THE AREA THROUGH SATURDAY...AND THEN BETTER CHANCES OF SHOWERS AND SOME THUNDERSTORMS BY SUNDAY. WHILE ACTIVITY MAY TAPER OFF A BIT ON MONDAY...THE CENTRAL CONUS TROUGH WOULD STILL BE TO OUR WEST...AND BE A FEATURE TO POTENTIALLY INFLUENCE OUR WEATHER PAST DAY 7. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 200 AM EDT TUESDAY... BETWEEN 06Z AND 12Z THERE WILL BE ANOTHER WAVE OF SHOWERS WITH MODERATE RAINFALL AND ISOLATED THUNDER MOVING FROM KY INTO SOUTHEAST WV AND LIKELY TO IMPACT BLF/LWB AGAIN WITH PERIODS OF IFR CONDITIONS. LEFT MENTION OF THUNDER OUT OF LWB HOWEVER AS LINGER WEAK INSTABILITY CONFINED A LITTLE FARTHER SOUTH. MORE SHALLOW CONVECTION ORGANIZATION CONTINUES TO DEVELOP UPSTREAM SO THERE MAY NOT BE TOO MANY BREAKS IN PRECIP ACTIVITY...AND FOG MAY NOT BE AS DENSE AS ONCE EXPECTED AT LWB UNLESS SOME REAL BREAKS IN PRECIP CAN OCCUR LATE. THUS MAKING FOR TROUBLESOME TAF FORECAST ESPECIALLY AT THESE SITES. FARTHER EAST EXPECT A FEW SHOWERS MAY REACH BCB/ROA/LYH BY 08Z TO 09Z BUT CIGS SHOULD REMAIN VFR OR MVFR...WITH EXCEPTION OF BCB...BUT LIKELY TO GET SOME IFR FOG FARTHER EAST LATE TONIGHT. OVERALL...EXPECT THE USUAL HARD TO PIN DOWN FLUCTUATION BETWEEN IFR/LIFR TO VFR AT TIMES THROUGH EARLY MORNING GIVEN THE TROPICAL AIRMASS AND THREAT OF SHOWERS. FOR TUESDAY THE FRONT SHIFTS SLOWLY SOUTHEAST AND TURNS THE WINDS TO THE WNW BY AFTERNOON. EXPECT MOST OF THE CONVECTION IN THE MORNING IN THE WEST TO TRANSFER EAST OF THE MOUNTAINS IN THE AFTERNOON. COVERAGE FOR SHOWERS SHOULD BE 50/50 AT LEAST IF NOT MORE BUT KEPT THUNDER OUT OF THE PREDOMINANT GROUP FOR NOW...BUT LEFT IN VICINITY. MAINLY VFR CONDITIONS FOR THE DAY...EXCEPT IN THE CASE THAT ANY HEAVIER RAIN OR STORMS MOVE RIGHT OVER AN AIRPORT. THE COLD FRONT...AND ASSOCIATED HIGH PRESSURE...WILL LIKELY BE STRONG ENOUGH TO PUSH THE TROPICAL AIRMASS OUT OF THE AREA FOR A COUPLE OF DAYS...BRINGING A GOOD OPPORTUNITY FOR WIDESPREAD VFR WEATHER THAT MAY LAST OVER MUCH OF THE AREA LATER TUESDAY NIGHT INTO THURSDAY BEFORE MOISTURE BEGINS TO RETURN NORTHWARD ON THE BACK SIDE OF THE HIGH LATE IN THE WEEK. ONE EXCEPTION WILL BE AT THE SOUTHEASTERN WV TERMINAL FORECAST SITES WHERE RETURN TO VFR WEATHER WITH NO FLIGHT RESTRICTIONS MAY BE DELAYED UNTIL MID TO LATE WEDNESDAY DUE TO COOL UPSLOPING WINDS AND LINGERNIG LOW CLOUDS AND PERHAPS EVEN SOME DRIZZLE TUES NIGHT. && .HYDROLOGY... AS OF 355 PM EDT MONDAY... NO CHANGES TO FLASH FLOOD WATCH. SOME AREAS RECEIVED 3"+ OVER THE MOUNTAIN EMPIRE OF SW VA...INCLUDING THE RICHLANDS AREA. MORE HEAVIER DOWNPOURS ARE POSSIBLE AGAIN OVERNIGHT AND TUESDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR VAZ007-009>017-032. NC...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NCZ001>003-018-019. WV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR WVZ042>045. && $$ SYNOPSIS...SK NEAR TERM...SK SHORT TERM...NF LONG TERM...DS/NF AVIATION...CF/SK/WP HYDROLOGY...AMS/SK
AREA FORECAST DISCUSSION
NWS SPOKANE WA
245 PM PDT Tue Aug 13 2013 .SYNOPSIS... A warming and drying trend arrives Wednesday and lingers into Thursday. A weak cold front will move into the Cascades Thursday afternoon then trickle across the Inland NW Friday and Saturday. This will bring a chance for light showers and a few thunderstorms along with near normal temperatures and locally breezy winds. Seasonal temperatures and dry conditions will return Sunday into early next week. && .DISCUSSION... Tonight: It appears as though there are only a couple of spots of concern for thunderstorms for the remainder of the afternoon into the evening. The Blue Mountains, the Camas Prairie and the mountains of the Idaho Panhandle. Synoptic scale forcing is weak region wide. As of 2 PM, a small scale vorticity max was moving out of the southern Idaho Panhandle into western Montana. This mesoscale feature should enhance the thunderstorm potential in northwest Montana this evening. The RUC surface CAPE/CIN analysis suggests that Shoshone, Boundary, Bonner and Pend O`Reille counties are essentially uncapped with as much as 2000 J/KG of surface based instability. The HRRR suggests that a few thunderstorms will develop between 4 PM and 6 PM over central and southern Shoshone county. It will be interesting to see if convection will develop in the wake of the departing vorticity center. Forecasters usually imply that there is subsidence behind these small vort maxes to suppress convection. I am more confident that a storm or two will develop over the Blues and over the peaks near Bonners Ferry. The threat for thunderstorms will decrease quickly this evening with the loss of surface heating. By 8 PM, look for clearing skies region-wide. Wednesday: Hot temperatures will return on Wednesday with low to mid 90s common over the Inland Northwest. Both the NAM and GFS forecast a bit of moisture at 700mb Wednesday morning, advancing northward through the Columbia Basin. This will probably not be enough moisture to produce high based showers, but we will need to monitor satellite and radar imagery tonight for the potential of some light, high based showers in the morning. Otherwise, large scale subsidence under a building upper ridge axis will cause temperatures to warm a good 3 to 6 degrees tomorrow over today. /GKoch Wednesday night through Saturday: Models are in strong agreement that the trof of low pressure currently spinning over the Gulf of AK will eject east and pass through the Inland NW ushering a cool front across the region. This will bring a chance for showers and a few thunderstorms along with a cooling trend, and a slight increase in winds. The cool front will be reaching the Cascades around mid to late afternoon on Thursday then slowly trickle across Ern Wa and Nrn ID during the next 48 hours...barely clearing ID and Ern OR by Saturday afternoon. This is exceptionally slower then models were forecasting 24 hours ago but does make sense based on how the upper-level jet parallels the front. So what does this mean? Well, there are a few items of interest that could alter the forecast. All models agree that there will be a rich but narrow fetch of subtropical moisture absorbed into the system...running along/ahead of the frontal boundary. So increased clouds are a definite but given the slow movement of the front and weakening thermal structure of the front upon crossing into Ern WA...lift along the frontal boundary will be mediocre. As such, precipitation along the front will be light and generally in a slow, top-down saturation regime. This does not mean the region will escape dry for better chances for precipitation will come in two other forms. The first will focus on smaller shortwaves swinging around the parent low and tracking SW to NE along the baroclinic/frontal zone. GFS is most robust with these waves but other models do show these features in one form or another and looking at current water vapor, the first wave that will swing through on Thursday is evident via sharp area of darkening near 46N/155W. These are the waves that tend to bring a quick burst of showers along slow moving frontal systems that start off looking rather dry as this did on yesterday`s models. The second feature will be convection (ie thunderstorms). This pattern does not look overly impressive or unstable for thunderstorms but it is August and timing will be key. We did maintain a small threat for thunder over the Cascades Thursday aftn however clouds should thickening throughout the day and I am not real confident we can achieve the 500 J/kg of sb CAPE showing up on the models Thursday aftn in this area. A better threat for thunderstorms will come across Ern WA and ID Panhandle Friday afternoon and Saturday as the front trickles this way/stalls and works in conjunction with peak heating. Model soundings indicate a modest layer of CIN for most locations away from the far northern mountains so the lift along the front will be necessary to lift these parcels and utilize the instability but given the weakening nature of the front, we kept the main threat for thunderstorms across the mountains or slightly downstream of the steering flow. All things considered, models are generally indicating light pcpn with this event with the exception of the more robust GFS which has a few quarter inch bull-eyes...one over the NE Mtns and second near the Blue Mtns...and for reasoning above...the forecast may need to trend wetter as these two features become more apparent. /sb Saturday Night through Tuesday Night: As the trough that brought the chance for showers and thunderstorms to much of the region exits to the east Saturday evening into Sunday we will see slight chance remain for some showers and isolated t-storms for mainly the northern ID Panhandle. As this pushes to the east our region will be left with a general westerly flow. Most of the moisture with this flow will remain to our north keeping the chance for precipitation low. Also with the zonal flow we will not see many changes in our temperatures with most areas sitting in the 80s for highs and upper 50s to lower 60s for overnight lows. Winds will die off from the breezy conditions we saw Saturday and look to remain seasonal for the early part of next week. Models are hinting at a wave dropping down from the Gulf of Alaska during the middle part of next week...but with consistency between the solutions lacking we will hold off on any major changes to the forecast that far out for now. /Fliehman && .AVIATION... 18Z TAFS: VFR conditions are expected through 14/18z. The only weather of consequence will be the potential for showers and isolated thunderstorms over the Idaho panhandle. The thunderstorms look like they will miss KCOE to the east, but updates will be likely if the precipitation moves further west. All activity expected to die off after sunset. ty && .PRELIMINARY POINT TEMPS/POPS... Spokane 62 92 66 89 65 85 / 10 10 0 0 10 20 Coeur d`Alene 57 92 60 90 60 85 / 10 10 0 0 10 20 Pullman 51 92 54 90 57 86 / 0 10 0 0 10 20 Lewiston 64 100 66 98 66 94 / 10 0 0 0 0 10 Colville 53 95 57 93 59 87 / 0 10 0 10 20 20 Sandpoint 51 89 53 90 56 87 / 10 10 0 0 10 20 Kellogg 56 91 59 90 57 89 / 20 0 0 0 10 20 Moses Lake 59 95 64 93 65 90 / 10 10 0 10 10 10 Wenatchee 64 93 69 91 67 89 / 10 10 0 10 10 20 Omak 60 95 63 93 63 90 / 0 10 10 10 10 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
604 PM CDT WED AUG 14 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 333 PM CDT WED AUG 14 2013 AT 3 PM...THE SATELLITE LOOP SHOWED A BROKEN DECK OF 7 TO 8K FOOT CLOUDS ACROSS THE FORECAST AREA. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THESE CLOUDS AND THEY SHOW THAT THESE CLOUDS WILL GRADUALLY DISSIPATE THIS EVENING. FOR LATE TONIGHT AND THURSDAY MORNING...THE BUFKIT SOUNDINGS SHOW THAT THERE WILL BE A DEEP LAYER /UP TO 775 MB/ OF LIGHT WINDS ACROSS THE AREA. WHILE THIS WOULD BE FAVORABLE FOR THE DEVELOPMENT OF VALLEY FOG. THE NAM/WRF...GFS...AND RAP CONTINUE TO SHOW THAT THE TEMPERATURE/DEW POINT SPREAD WILL REMAIN AT OR ABOVE 1C. IN ADDITION...THE GFS AND NAM/WRF SUGGEST THAT THERE COULD BE STILL SOME CLOUDS AROUND THE REGION. AS A RESULT...WENT WITH PATCHY VALLEY FOG FOR THE MISSISSIPPI RIVER AND ITS TRIBUTARIES...AND AREAS OF FOG IN THE WISCONSIN RIVER VALLEY. ON THURSDAY...THE MODELS CONTINUE TO SHOW THAT A SHORT WAVE TROUGH WILL MOVE SOUTHEAST ACROSS SOUTHERN AND WESTERN IOWA. WEAK 925 AND 850 MB MOISTURE TRANSPORT NORTHEAST OF THIS SYSTEM WILL AID IN THE DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS NORTHEAST IOWA...SOUTHEAST MINNESOTA...AND SOUTHWEST WISCONSIN. WITH ML CAPES LESS THAN 400 J/KG AND VERY WEAK 0-3 KM AND 0-6 KM...NONE OF THESE THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 333 PM CDT WED AUG 14 2013 ON FRIDAY...THE 925 MB AND 850 MB WEAK MOISTURE TRANSPORT AND 700 TO 600 MB FRONTOGENESIS REMAINS SOUTHWEST OF THE FORECAST AREA. IN ADDITION...THERE IS VERY LITTLE SURFACE MOISTURE CONVERGENCE ACROSS THE AREA. WITH THE MESO MODELS IN AGREEMENT WITH THE GEM AND ECMWF THAT THE AREA WILL REMAIN DRY...REMOVED THE PRECIPITATION CHANCES FOR THIS TIME PERIOD. ON BOTH THURSDAY AND FRIDAY NIGHTS...BOTH THE GFS AND NAM/WRF SOUNDINGS SHOW A DEEP LAYER /UP TO AT LEAST 800 MB/ OF LIGHT WINDS. THIS WOULD BE VERY FAVORABLE FOR THE DEVELOPMENT OF VALLEY FOG. HOWEVER THEY ALSO HINT THAT THERE MAY BE SOME CLOUDS AROUND THE REGION. ANOTHER FACTOR THAT MAY BE A LIMITING FACTOR IS THE AMOUNT OF MOISTURE IN THE BOUNDARY LAYER. THE NAM/WRF HAS MUCH MORE MOISTURE THAN THE GFS. DUE TO THIS UNCERTAINTY...JUST INTRODUCED PATCHY TO AREAS OF VALLEY FOG ON BOTH NIGHTS. FROM MONDAY THROUGH WEDNESDAY...THE MODELS ARE CONTINUING TO STRUGGLE WITH THE 500 MB UPPER AIR PATTERN. THE GFS AND GEM ARE SHOWING THAT THE UPPER LEVEL RIDGE REMAINS LONGER TO THE WEST THAN THE ECMWF. AS A RESULT...THE GFS AND GEM ARE FASTER AT MOVING THE COLD FRONT SOUTHEAST INTO THE FORECAST AREA. MEANWHILE THE ECMWF HAS THE FRONT REMAINING WELL NORTHWEST OF THE FORECAST AREA. SINCE THE MODELS HAVE BEEN TRENDING SLOWER DURING THIS TIME PERIOD...THE CONSENSUS OF OUR OFFICE AND THE SURROUNDING WFOS TO KEEP MOST OF THE FORECAST AREA DRY DURING THIS TIME FRAME. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 604 PM CDT WED AUG 14 2013 FORECAST CONCERN IS ON VALLEY FOG POTENTIAL AT LSE. SCT-BKN HIGH BASED CUMULUS PERSISTS AROUND BOTH TAF SITES. SOME OF THESE ARE DIURNALLY DRIVEN AND ARE DISSIPATING NOW WITH LOSS OF HEATING... HOWEVER...OTHERS ARE PERSISTING. VARIOUS MODELS...RAP...NAM... GFS...ALL DEPICT THAT THE MOISTURE AROUND 7000 FT AGL WILL STICK AROUND THROUGH THE NIGHT AND THROUGH THE DAY THURSDAY AT BOTH SITES. THIS MOISTURE SHOULD CONTINUE TO MANIFEST ITSELF AS SCT-BKN HIGH BASED CUMULUS. THEREFORE...DESPITE A LIGHT WIND PROFILE UP TO 5000 FT AGL OR HIGHER AT LSE THAT WOULD BE FAVORABLE FOR VALLEY FOG...THESE CLOUDS GREATLY THROW FOG INTO QUESTION. THEREFORE...HAVE LEFT VALLEY FOG OUT OF THE LSE FORECAST. SHOULD MORE CLEARING OCCUR...THE CONCERN FOR VALLEY FOG WILL INCREASE. OTHERWISE...VFR CONDITIONS CONTINUE THROUGH THURSDAY WITH PERHAPS JUST A SLIGHT CHANCE FOR AN AFTERNOON SHOWER AT RST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...AJ
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1216 PM MDT TUE AUG 13 2013 .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 300 AM MDT TUE AUG 13 2013 CURRENTLY...LOOKING AT MOSAIC RADAR...OUR CWFA IS PRETTY MUCH ECHO FREE WITH A LINE OF THUNDERSTORMS PUSHING SOUTHEAST IN CENTRAL NEBRASKA AT 1 AM THIS MORNING. FRONTAL BOUNDARY STILL LAYS UP ALONG THE LARAMIE RANGE THIS MORNING...EXTENDING NORTHWEST INTO CENTRAL MONTANA. TO OUR NORTH...A COMPLEX OF THUNDERSTORMS LAYS ACROSS EASTERN MONTANA JUST EAST OF THE FRONT. IT REMAINS TO BE SEEN WHAT THAT LINE OF THUNDERSTORMS OVER NEBRASKA WILL DO TO OUR LOW LEVEL MOISTURE. IT HAS CAUSED WINDS TO BECOME MORE SOUTHWESTERLY AND THEREFORE A LITTLE DRIER IN THE PANHANDLE SO FAR. LATEST 11U-3.9U SATELLITE IMAGERY HAS YET TO SHOW THE ANTICIPATED STRATUS DEVELOPING YET. THE MORNING SHOULD START OFF DRY WITH INCREASING SHOWERS AND THUNDERSTORMS DEVELOPING BY NOON. LATEST HRRR COMPOSITE REFLECTIVITY FORECAST HAS SHOWERS DEVELOPING OVER THE MOUNTAINS TO THE WEST OF CHEYENNE BY 17Z AND REALLY INCREASING IN COVERAGE AFTER 19Z. THIS CORRESPONDS WELL WITH THE 00Z ECMWF FORECAST FOR THE UPPER VORT MAX TO MOVE THROUGH THE UPPER RIDGE THIS AFTERNOON. FORECAST STORM MOTIONS THIS AFTERNOON ON THE NAM SOUNDINGS SHOW STORMS TO BE ALMOST STATIONARY. SOME LOCATIONS ARE GOING TO SEE SOME HEAVY RAINFALL...LIKELY LEADING TO SOME FLASH FLOODING. CONFIDENCE NO HIGH ON WHERE THESE THUNDERSTORMS ARE GOING TO DEVELOP...SO WILL HOLD OFF ON ANY WATCHES. BUT DO EXPECT US TO BE ISSUING FLASH FLOOD WARNINGS FOR SOME AREAS TODAY. UPPER VORT MAX STAYS WITH US THROUGH THE OVERNIGHT HOURS TONIGHT...FINALLY EXITING SOUTHEAST WEDNESDAY AFTERNOON. DID KEEP FAIRLY HIGH POPS GOING TONIGHT THROUGH AT LEAST MIDNIGHT...THEN PICKING UP AGAIN WEDNESDAY AFTERNOON WITH DAYTIME HEATING. PATTERN CHANGE THEN BEGINS WEDNESDAY NIGHT INTO THURSDAY AS THE ECMWF BUILDS THE UPPER LEVEL RIDGE. WITH THE BUILDING RIDGE...THE DRIER AIR OVER UTAH AND SOUTHERN COLORADO WILL FILTER INTO THE AREA DURING THE DAY THURSDAY. .LONG TERM...(THURSDAY NIGHT THROUGH MONDAY) ISSUED AT 242 AM MDT TUE AUG 13 2013 ALL LONG RANGE MODELS IN AGREEMENT...SHOWING A BREAK IN THE PERSISTENT MOIST WEATHER PATTERN ACROSS THE FORECAST AREA LATE THIS WEEK. A DRYING TREND WILL CONTINUE THROUGH SATURDAY WITH WARMER TEMPERATURES IN THE 80S AND LOW 90S EXPECTED. THE WARMEST DAY WILL LIKELY BE SATURDAY AS THE RIDGE AXIS SHIFTS EASTWARD INTO THE PLAINS...WITH HIGHS IN THE MID 80S TO MID 90S EXPECTED...WARMEST ACROSS THE LOWER ELEVATIONS BELOW 5000 FEET. KEPT POP BELOW 10 PERCENT WITH LIMITED CLOUD COVER. KEPT TEMPERATURES A FEW DEGREES BELOW MOS FOR NOW...SINCE IT IS UNCLEAR HOW THE CURRENT SOIL MOISTURE WILL IMPACT TEMPERATURES AND HUMIDITY. WITH LIGHT WINDS EXPECTED...DO NOT BELIEVE THE NEAR SURFACE MOISTURE WILL BE ADVECTED EASTWARD AS THAT QUICK. PRECIPITATION CHANCES WILL RETURN TO THE AREA BY LATE SUNDAY AND INTO MONDAY OF NEXT WEEK AS A FAST MOVING PACIFIC TROUGH PUSHES ACROSS THE NORTHERN AND CENTRAL ROCKIES. SOME COOLER AIR WILL PUSH INTO THE REGION AS WELL WITH HIGH TEMPERATURES 5 TO 10 DEGREES COOLER COMPARED TO FRIDAY/SATURDAY. INCREASED POP BETWEEN 20 TO 40 PERCENT FOR SHOWERS AND TSTORMS SUNDAY AND MONDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING) ISSUED AT 1210 PM MDT TUE AUG 13 2013 MAINLY VFR CONDITIONS THROUGH THE TAF PERIOD. SCATTERED SHOWERS AND TSTMS WILL DEVELOP IN SOUTHEAST WY BY AROUND 20Z AND THEN SPREAD EASTWARD ACROSS THE PLAINS THROUGH THE EVENING. SOME OF THE STORMS COULD PRODUCE HEAVIER DOWNPOURS AND BRIEF MVFR VIS. SHOWERS COULD LINGER OVER THE PANHANDLE THROUGH THE EARLY MORNING ON WEDNESDAY. WINDS SHOULD GENERALLY REMAIN BELOW 10-15 KTS...HOWEVER GUSTY WINDS TO 30 KTS COULD OCCUR IN THE VICINITY OF STORMS. && .FIRE WEATHER... ISSUED AT 300 AM MDT TUE AUG 13 2013 CURRENT THINKING IS THAT FIRE WEATHER CONCERNS WILL BE MINOR TODAY AND WEDNESDAY AS MONSOONAL MOISTURE OVER WYOMING WILL CREATE WIDESPREAD WETTING RAINS FOR MOST LOCATIONS. DRIER AIR BEGINS TO MOVE INTO THE AREA WEDNESDAY NIGHT INTO THURSDAY. AFTERNOON HUMIDITIES FORECAST TO BE IN THE SINGLE DIGITS ACROSS CARBON COUNTY THURSDAY AFTERNOON. WINDS ARE EXPECTED TO REMAIN FAIRLY LIGHT THOUGH AND SHOULD PRECLUDE ANY FIRE WEATHER CONCERNS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...FINCH FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
546 AM MDT TUE AUG 13 2013 .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 300 AM MDT TUE AUG 13 2013 CURRENTLY...LOOKING AT MOSAIC RADAR...OUR CWFA IS PRETTY MUCH ECHO FREE WITH A LINE OF THUNDERSTORMS PUSHING SOUTHEAST IN CENTRAL NEBRASKA AT 1 AM THIS MORNING. FRONTAL BOUNDARY STILL LAYS UP ALONG THE LARAMIE RANGE THIS MORNING...EXTENDING NORTHWEST INTO CENTRAL MONTANA. TO OUR NORTH...A COMPLEX OF THUNDERSTORMS LAYS ACROSS EASTERN MONTANA JUST EAST OF THE FRONT. IT REMAINS TO BE SEEN WHAT THAT LINE OF THUNDERSTORMS OVER NEBRASKA WILL DO TO OUR LOW LEVEL MOISTURE. IT HAS CAUSED WINDS TO BECOME MORE SOUTHWESTERLY AND THEREFORE A LITTLE DRIER IN THE PANHANDLE SO FAR. LATEST 11U-3.9U SATELLITE IMAGERY HAS YET TO SHOW THE ANTICIPATED STRATUS DEVELOPING YET. THE MORNING SHOULD START OFF DRY WITH INCREASING SHOWERS AND THUNDERSTORMS DEVELOPING BY NOON. LATEST HRRR COMPOSITE REFLECTIVITY FORECAST HAS SHOWERS DEVELOPING OVER THE MOUNTAINS TO THE WEST OF CHEYENNE BY 17Z AND REALLY INCREASING IN COVERAGE AFTER 19Z. THIS CORRESPONDS WELL WITH THE 00Z ECMWF FORECAST FOR THE UPPER VORT MAX TO MOVE THROUGH THE UPPER RIDGE THIS AFTERNOON. FORECAST STORM MOTIONS THIS AFTERNOON ON THE NAM SOUNDINGS SHOW STORMS TO BE ALMOST STATIONARY. SOME LOCATIONS ARE GOING TO SEE SOME HEAVY RAINFALL...LIKELY LEADING TO SOME FLASH FLOODING. CONFIDENCE NO HIGH ON WHERE THESE THUNDERSTORMS ARE GOING TO DEVELOP...SO WILL HOLD OFF ON ANY WATCHES. BUT DO EXPECT US TO BE ISSUING FLASH FLOOD WARNINGS FOR SOME AREAS TODAY. UPPER VORT MAX STAYS WITH US THROUGH THE OVERNIGHT HOURS TONIGHT...FINALLY EXITING SOUTHEAST WEDNESDAY AFTERNOON. DID KEEP FAIRLY HIGH POPS GOING TONIGHT THROUGH AT LEAST MIDNIGHT...THEN PICKING UP AGAIN WEDNESDAY AFTERNOON WITH DAYTIME HEATING. PATTERN CHANGE THEN BEGINS WEDNESDAY NIGHT INTO THURSDAY AS THE ECMWF BUILDS THE UPPER LEVEL RIDGE. WITH THE BUILDING RIDGE...THE DRIER AIR OVER UTAH AND SOUTHERN COLORADO WILL FILTER INTO THE AREA DURING THE DAY THURSDAY. .LONG TERM...(THURSDAY NIGHT THROUGH MONDAY) ISSUED AT 242 AM MDT TUE AUG 13 2013 ALL LONG RANGE MODELS IN AGREEMENT...SHOWING A BREAK IN THE PERSISTENT MOIST WEATHER PATTERN ACROSS THE FORECAST AREA LATE THIS WEEK. A DRYING TREND WILL CONTINUE THROUGH SATURDAY WITH WARMER TEMPERATURES IN THE 80S AND LOW 90S EXPECTED. THE WARMEST DAY WILL LIKELY BE SATURDAY AS THE RIDGE AXIS SHIFTS EASTWARD INTO THE PLAINS...WITH HIGHS IN THE MID 80S TO MID 90S EXPECTED...WARMEST ACROSS THE LOWER ELEVATIONS BELOW 5000 FEET. KEPT POP BELOW 10 PERCENT WITH LIMITED CLOUD COVER. KEPT TEMPERATURES A FEW DEGREES BELOW MOS FOR NOW...SINCE IT IS UNCLEAR HOW THE CURRENT SOIL MOISTURE WILL IMPACT TEMPERATURES AND HUMIDITY. WITH LIGHT WINDS EXPECTED...DO NOT BELIEVE THE NEAR SURFACE MOISTURE WILL BE ADVECTED EASTWARD AS THAT QUICK. PRECIPITATION CHANCES WILL RETURN TO THE AREA BY LATE SUNDAY AND INTO MONDAY OF NEXT WEEK AS A FAST MOVING PACIFIC TROUGH PUSHES ACROSS THE NORTHERN AND CENTRAL ROCKIES. SOME COOLER AIR WILL PUSH INTO THE REGION AS WELL WITH HIGH TEMPERATURES 5 TO 10 DEGREES COOLER COMPARED TO FRIDAY/SATURDAY. INCREASED POP BETWEEN 20 TO 40 PERCENT FOR SHOWERS AND TSTORMS SUNDAY AND MONDAY. && .AVIATION...(FOR THE 12Z TAF ISSUANCE) LOW CIGS AND PATCHY FOG HAVE STRUGGLED TO DEVELOP ACROSS WESTERN NEBRASKA EARLY THIS MORNING. KCDR WILL CONTINUE WITH A LOW CIG AROUND 500 TO 1000 FEET AGL EARLY THIS MORNING BEFORE THE CLOUDS LIFT AND DISSIPATE BY 14Z. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS IS EXPECTED...FIRST DEVELOPING OVER SOUTHEAST WYOMING EARLY THIS AFTERNOON WITH VCTS AT KRWL AND KLAR BY 19Z...AND THEN MOVING EASTWARD ACROSS THE HIGH PLAINS BY MID TO LATE AFTERNOON. THUNDERSTORMS MAY CONTAIN ERRATIC GUSTY WINDS UP TO 45 KNOTS...HEAVY RAINFALL...AND FREQUENT LIGHTNING BEFORE DISSIPATING LATE THIS EVENING. && .FIRE WEATHER... ISSUED AT 300 AM MDT TUE AUG 13 2013 CURRENT THINKING IS THAT FIRE WEATHER CONCERNS WILL BE MINOR TODAY AND WEDNESDAY AS MONSOONAL MOISTURE OVER WYOMING WILL CREATE WIDESPREAD WETTING RAINS FOR MOST LOCATIONS. DRIER AIR BEGINS TO MOVE INTO THE AREA WEDNESDAY NIGHT INTO THURSDAY. AFTERNOON HUMIDITIES FORECAST TO BE IN THE SINGLE DIGITS ACROSS CARBON COUNTY THURSDAY AFTERNOON. WINDS ARE EXPECTED TO REMAIN FAIRLY LIGHT THOUGH AND SHOULD PRECLUDE ANY FIRE WEATHER CONCERNS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...TJT FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
346 AM MDT TUE AUG 13 2013 .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 300 AM MDT TUE AUG 13 2013 CURRENTLY...LOOKING AT MOSAIC RADAR...OUR CWFA IS PRETTY MUCH ECHO FREE WITH A LINE OF THUNDERSTORMS PUSHING SOUTHEAST IN CENTRAL NEBRASKA AT 1 AM THIS MORNING. FRONTAL BOUNDARY STILL LAYS UP ALONG THE LARAMIE RANGE THIS MORNING...EXTENDING NORTHWEST INTO CENTRAL MONTANA. TO OUR NORTH...A COMPLEX OF THUNDERSTORMS LAYS ACROSS EASTERN MONTANA JUST EAST OF THE FRONT. IT REMAINS TO BE SEEN WHAT THAT LINE OF THUNDERSTORMS OVER NEBRASKA WILL DO TO OUR LOW LEVEL MOISTURE. IT HAS CAUSED WINDS TO BECOME MORE SOUTHWESTERLY AND THEREFORE A LITTLE DRIER IN THE PANHANDLE SO FAR. LATEST 11U-3.9U SATELLITE IMAGERY HAS YET TO SHOW THE ANTICIPATED STRATUS DEVELOPING YET. THE MORNING SHOULD START OFF DRY WITH INCREASING SHOWERS AND THUNDERSTORMS DEVELOPING BY NOON. LATEST HRRR COMPOSITE REFLECTIVITY FORECAST HAS SHOWERS DEVELOPING OVER THE MOUNTAINS TO THE WEST OF CHEYENNE BY 17Z AND REALLY INCREASING IN COVERAGE AFTER 19Z. THIS CORRESPONDS WELL WITH THE 00Z ECMWF FORECAST FOR THE UPPER VORT MAX TO MOVE THROUGH THE UPPER RIDGE THIS AFTERNOON. FORECAST STORM MOTIONS THIS AFTERNOON ON THE NAM SOUNDINGS SHOW STORMS TO BE ALMOST STATIONARY. SOME LOCATIONS ARE GOING TO SEE SOME HEAVY RAINFALL...LIKELY LEADING TO SOME FLASH FLOODING. CONFIDENCE NO HIGH ON WHERE THESE THUNDERSTORMS ARE GOING TO DEVELOP...SO WILL HOLD OFF ON ANY WATCHES. BUT DO EXPECT US TO BE ISSUING FLASH FLOOD WARNINGS FOR SOME AREAS TODAY. UPPER VORT MAX STAYS WITH US THROUGH THE OVERNIGHT HOURS TONIGHT...FINALLY EXITING SOUTHEAST WEDNESDAY AFTERNOON. DID KEEP FAIRLY HIGH POPS GOING TONIGHT THROUGH AT LEAST MIDNIGHT...THEN PICKING UP AGAIN WEDNESDAY AFTERNOON WITH DAYTIME HEATING. PATTERN CHANGE THEN BEGINS WEDNESDAY NIGHT INTO THURSDAY AS THE ECMWF BUILDS THE UPPER LEVEL RIDGE. WITH THE BUILDING RIDGE...THE DRIER AIR OVER UTAH AND SOUTHERN COLORADO WILL FILTER INTO THE AREA DURING THE DAY THURSDAY. .LONG TERM...(THURSDAY NIGHT THROUGH MONDAY) ISSUED AT 242 AM MDT TUE AUG 13 2013 ALL LONG RANGE MODELS IN AGREEMENT...SHOWING A BREAK IN THE PERSISTENT MOIST WEATHER PATTERN ACROSS THE FORECAST AREA LATE THIS WEEK. A DRYING TREND WILL CONTINUE THROUGH SATURDAY WITH WARMER TEMPERATURES IN THE 80S AND LOW 90S EXPECTED. THE WARMEST DAY WILL LIKELY BE SATURDAY AS THE RIDGE AXIS SHIFTS EASTWARD INTO THE PLAINS...WITH HIGHS IN THE MID 80S TO MID 90S EXPECTED...WARMEST ACROSS THE LOWER ELEVATIONS BELOW 5000 FEET. KEPT POP BELOW 10 PERCENT WITH LIMITED CLOUD COVER. KEPT TEMPERATURES A FEW DEGREES BELOW MOS FOR NOW...SINCE IT IS UNCLEAR HOW THE CURRENT SOIL MOISTURE WILL IMPACT TEMPERATURES AND HUMIDITY. WITH LIGHT WINDS EXPECTED...DO NOT BELIEVE THE NEAR SURFACE MOISTURE WILL BE ADVECTED EASTWARD AS THAT QUICK. PRECIPITATION CHANCES WILL RETURN TO THE AREA BY LATE SUNDAY AND INTO MONDAY OF NEXT WEEK AS A FAST MOVING PACIFIC TROUGH PUSHES ACROSS THE NORTHERN AND CENTRAL ROCKIES. SOME COOLER AIR WILL PUSH INTO THE REGION AS WELL WITH HIGH TEMPERATURES 5 TO 10 DEGREES COOLER COMPARED TO FRIDAY/SATURDAY. INCREASED POP BETWEEN 20 TO 40 PERCENT FOR SHOWERS AND TSTORMS SUNDAY AND MONDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 944 PM MDT MON AUG 12 2013 THROUGH 07Z...ISOLATED SHOWERS EAST OF A DOUGLAS TO CHEYENNE LINE. FROM 10Z TO 16Z...AREAS OF LOW CLOUDS AND FOG AT NEBRASKA AERODROMES WITH LOCALIZED IFR AND MVFR...VFR ELSEWHERE. AFTER 20Z TUESDAY...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS PRODUCING LOCALIZED MVFR. && .FIRE WEATHER... ISSUED AT 300 AM MDT TUE AUG 13 2013 CURRENT THINKING IS THAT FIRE WEATHER CONCERNS WILL BE MINOR TODAY AND WEDNESDAY AS MONSOONAL MOISTURE OVER WYOMING WILL CREATE WIDESPREAD WETTING RAINS FOR MOST LOCATIONS. DRIER AIR BEGINS TO MOVE INTO THE AREA WEDNESDAY NIGHT INTO THURSDAY. AFTERNOON HUMIDITIES FORECAST TO BE IN THE SINGLE DIGITS ACROSS CARBON COUNTY THURSDAY AFTERNOON. WINDS ARE EXPECTED TO REMAIN FAIRLY LIGHT THOUGH AND SHOULD PRECLUDE ANY FIRE WEATHER CONCERNS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...TJT FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1209 AM CDT Thu Aug 15 2013 .SHORT TERM...(This Evening through Friday Afternoon) Issued at 257 PM CDT WED AUG 14 2013 The main focus in the short-term remains a series of shortwave troughs sinking southeastward across the Plains this evening, Thursday, and into early Friday. Showers and isolated storms have developed over portions of eastern Nebraska in association with a wave currently pushing southeast toward the forecast area; however, ongoing precipitation will continue to move into fairly dry air this evening, and may struggle against entrainment. Additionally, upper- level flow may push the main area of precipitation more east than south, keeping the bulk of any falling precipitation in central and southern Iowa. Short-term precipitation trends from the HRRR have been fairly consistent today, and also generally limit the south and eastward expansion of showers for this evening and tonight. For now, have kept PoPs very low and confined to far northwest Missouri prior to 06z, then have begun to increase chances in the NW to account for possible regeneration as the low-level jet kicks up early Thursday morning. The next system will follow on the heels of tonight`s as it drops down from eastern Montana on Thursday. Models continue to indicate that the reinforcement of the eastern trough by a second upper low, and the retrograding of a broad upper high, will result in more meridional flow across the Plains for Thursday and Friday. This subtle change will send the second wave a bit west of the forecast area, keeping the better rain chances mainly across portions of central and eastern Kansas. Have left some slight to low-end chance PoPs mainly across the western tier or two of counties on Thursday afternoon and Thursday night, but these could likely be cut further if model trends continue in this direction. Any precipitation that does brush the area will sink southward on Friday morning, leaving behind quiet conditions by Friday afternoon. Temperatures through the period will remain ~10 degrees below normal as cool air continues to filter down the trough and into the eastern Plains and Ohio River valley, with highs generally topping out in the upper 70s to lower 80s, and lows in the 50s to lower 60s under surface high pressure. .LONG TERM...(Friday Evening through Wednesday) Issued at 257 PM CDT WED AUG 14 2013 A quiet medium range forecast for the Central Plains as mid-level ridging currently building over the Rockies begins to move eastward. Despite the increasing heights, Saturday will likely remain below seasonal normals as surface and low-level winds remain light to southeast. By Sunday, we`ll begin to see a steady climb back to or even above normal as winds turn southerly and warmer air begins to advect northward. The first half of next week will again feature quiet conditions as mid-level flow remains weak. Temperatures will have a chance to return to the 90 degree mark by Tuesday and Wednesday, a rare feat this August. && .AVIATION...(For the 06Z TAFS through 06Z Thursday Night) Issued at 1154 PM CDT WED AUG 14 2013 Still some uncertainty about whether showers will make it far enough south to affect KMCI/KMKC...as there may not be enough ascent to adequately saturate the column. As of now it looks as though the best chance for actual precipitation will be further north toward KSTJ and points north. Regardless of showery activity expect VFR conditions to be predominant through the entire period. Will continue to monitor and amend as necessary. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Laflin LONG TERM...Dux AVIATION...Leighton
AREA FORECAST DISCUSSION
NWS HASTINGS NE
431 AM CDT THU AUG 15 2013 ...SVR TSTMS POSSIBLE THIS AFTN-EVNG THEN WE HAVE A GORGEOUS DRY WEEKEND IN STORE FOR OUTDOOR ACTIVITIES... .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM CDT THU AUG 15 2013 ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY DAYBREAK FRI. SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE... THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO BE NEAR PUB BY SUNSET. FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS. EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED RAINFALL. THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE. THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS. WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA. WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500 J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER CLOUDINESS WHICH WILL RETARD DIURNAL HEATING. OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR /WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/. INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND 20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING SUPERCELL SPLITS A POSSIBILITY. MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1 KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY BOUNDARIES. TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE SKIES CLEAR. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 431 AM CDT THU AUG 15 2013 GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY. BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW 80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT THE LONG TERM FORECAST PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1237 AM CDT THU AUG 15 2013 REST OF TNGT: REMOVED FOG AND LOW CIGS FROM THE TAF BASED ON LBF/OAX SOUNDINGS AS WELL AS WIND AND DWPT TRENDS FROM YESTERDAY AFTN. EXPECT VFR CIGS MAY GO SCT AT TIMES. THERE IS A CLUSTER OF TSTMS OVER THE NEB PANHANDLE THAT WILL NEED TO BE MONITORED FOR POSSIBLE INSERTION INTO THE TAF TOWARD DAWN. S WINDS UNDER 10 KTS. THU: LOW-END VFR CIGS SHOULD INCREASE TO MID-LVL CIGS FROM THE REMNANTS OF NEARBY TSTM CLUSTER. BY 18Z...CURRENT EXPECTATION IS FOR SCT VFR CU TO DEVELOP WITH CB POSSIBLE AFTER 21Z. THERE IS A LOW PROBABILITY FOR 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES A DIRECT HIT FROM AN AFTN OR EVNG TSTM. S WINDS LESS THAN 10 KTS WILL BACK TO SE. THU EVNG: TSTM THREAT SHOULD BE OVER BY 03Z. WE ARE SEEING SIGNALS OF POSSIBLE IFR FOG AFTER 06Z. CIG CONFIDENCE: MEDIUM VSBY CONFIDENCE: HIGH WIND CONFIDENCE: HIGH WX CONFIDENCE: MEDIUM && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1243 AM CDT THU AUG 15 2013 .SYNOPSIS... ISSUED AT 330 PM CDT WED AUG 14 2013 SHOWER AND THUNDERSTORM ACTIVITY CURRENTLY EXISTS ACROSS NORTH- CENTRAL NEBRASKA AND IS MOVING EASTWARD SLOWLY. NEBRASKA IS UNDER NORTHWEST FLOW ALOFT WITH AN UPPER LEVEL WAVE IN EASTERN NEBRASKA AND ANOTHER OVER MONTANA. LOW LEVEL FLOW IS GENERALLY SOUTHERLY WITH AN AREA OF LOW PRESSURE OVER THE INTERMOUNTAIN WEST AND HIGH PRESSURE OVER THE UPPER MISSISSIPPI RIVER VALLEY. A WEAK BOUNDARY EXISTS ACROSS CENTRAL NEBRASKA...RUNNING FROM HOLT COUNTY SOUTHWEST TO CHASE COUNTY. && .UPDATE... ISSUED AT 945 PM CDT WED AUG 14 2013 HAVE ADJUSTED PRECIPITATION CHANCES ACROSS THE AREA NOW THAT ISOLATED CONVECTION HAS ENDED ACROSS THE AREA...FOR NOW. HOWEVER...CONVECTIVE COMPLEXES REMAIN ACROSS SOUTHWEST SD AND NORTHEAST CO. HRRR DOES TRY TO KEEP THE SD COMPLEX TOGETHER LONG ENOUGH TO MOVE INTO THE PANHANDLE AND INTO THE CENTRAL SANDHILLS. MID LEVEL LAPSE RATES WOULD SUPPORT SOME ADDITIONAL DEVELOPMENT SO HAVE LEFT SMALL CHANCES IN FOR NOW. OTHERWISE ADDED SOME PATCHY FOG EAST OF HIGHWAY 83 WHERE SMALL TEMP/DEW POINT SPREADS EXIST. UPDATE ISSUED AT 706 PM CDT WED AUG 14 2013 HAVE UPDATED EVENING FCST TO SLIGHTLY ADJUST PRECIP CHANCES. THUNDERSTORMS SHOWING A QUICK DECREASE IN COVERAGE AND INTENSITY OVER THE LAST 15 MINS. ADDITIONAL CONVECTION FURTHER WEST WILL APPROACH THE AREA LATER THIS EVENING...BUT OVERALL MID LEVEL LAPSE RATES DOES NOT LOOK FAVORABLE AT THIS POINT BUT WILL LOOK FURTHER INTO THIS. OTHERWISE REMAINDER OF FCST LOOKS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 THE THUNDERSTORM COMPLEX THAT STARTED OVER THE NORTHEAST HAS LINGERED THERE TODAY DUE TO A FAVORABLE LOW LEVEL JET...SOME MODEST ELEVATED CAPE...AND UPPER SUPPORT. A SURFACE BOUNDARY CURRENTLY RUNS FROM HOLT TO CHASE COUNTIES AND MAY BE THE FOCUS FOR A FEW THUNDERSTORMS THIS AFTERNOON/EVENING. THE SEVERE THREAT IS LOW AS DEEP SHEAR IS RUNNING AT 25 TO 30 KTS. AN ISOLATED SEVERE STORM OR TWO CANNOT BE RULED OUT...HOWEVER. AN UPPER LEVEL WAVE WILL PUSH INTO THE AREA FROM THE NORTHWEST LATE TONIGHT AND TOMORROW MORNING. AHEAD OF THIS WAVE...CLOUDS WILL INCREASE AND SO WILL A LOW LEVEL JET ACROSS WESTERN NEBRASKA. BELIEVE THERE MAY BE SOME LATE NIGHT THUNDERSTORMS ACROSS THE NORTHWEST LATE IN THE NIGHT AND EARLY TOMORROW MORNING. THE MAIN UPPER WAVE WILL DRIFT INTO CENTRAL NEBRASKA BY MIDDAY...AND SO BELIEVE ANY THUNDERSTORM ACTIVITY WOULD BE PRIMARILY DURING THE LATE MORNING TO AFTERNOON HOURS. SHEAR TOMORROW IS A LITTLE BETTER...30-35 KTS...ACROSS THE SOUTH. AS A RESULT...SPC HAS ISSUED A SLIGHT RISK FOR SEVERE WEATHER ACROSS THAT AREA FOR TOMORROW. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 FORECASTING CHALLENGES ARE LINGERING PRECIPITATION THURSDAY EVENING...FOG POTENTIAL OVERNIGHT THURSDAY NIGHT INTO FRIDAY MORNING...THEN TEMPERATURES. WITH RESPECT TO THUNDERSTORM CHANCES THURSDAY EVENING...THE MODELS ARE A LITTLE FASTER WITH SHORTWAVE ENERGY DROPPING SOUTH THURSDAY ACROSS THE DAKOTAS AND NEBRASKA. THIS WILL BRING AN EARLIER END TO PRECIPITATION BY LATE THURSDAY EVENING IN THE SRN CWA. BEHIND THE EXITING CONVECTION...CLEARING SKIES...STRONG RADIATIONAL COOLING AND MOIST BOUNDARY LAYER CONDS MAY LEAD TO THE FORMATION OF FOG OVERNIGHT THURSDAY NIGHT INTO EARLY FRIDAY MORNING. NAM AND GFS BUFR SOUNDINGS INDICATE A FAVORABLE ENVIRONMENT FOR FOG FORMATION...AS DOES THE MET AND MAV GUIDANCE ALONG AND SOUTH OF A LINE FROM BIG SPRINGS TO BARTLETT. DECIDED TO LEAVE FOG MENTION AS PATCHY ATTM...AS SREF PROBABILITIES ARE RUNNING AROUND 60 PERCENT FOR VISBYS BLO 1SM. FOR FRIDAY INTO SUNDAY NIGHT...RIDGING WILL BUILD EAST INTO THE CENTRAL AND NORTHERN PLAINS...LEADING TO NRLY FLOW ALOFT AND EFFECTIVELY CUTTING OFF ANY CHANCE FOR PCPN FRIDAY THROUGH SUNDAY. HIGHS WILL BEGIN TO CLIMB FROM THE LOWER TO MID 80S ON FRIDAY...TO THE MID 80S TO AROUND 90 BY THE END OF THE WEEKEND. FOR HIGHS AND LOWS...UTILIZED THE ADJMAV GUIDANCE AS IT HAS HAD THE BEST VERIFICATION OVER THE PAST COUPLE OF WEEKS AND AVOIDED THE HIGHER MEX NUMBERS WHICH HAD HIGHS IN THE 90S BY SUNDAY INTO MONDAY. THINKING ATTM IS THAT THE MEX NUMBERS ARE TOO HIGH GIVEN THE HIGH DEGREE OF SURFACE MOISTURE ACROSS THE AREA. RIDGING ALOFT WILL BEGIN TO BREAK DOWN SLIGHTLY EARLY NEXT WEEK AS A DISTURBANCE TRACKS ACROSS SRN CANADA. THIS FEATURE HAS TRENDED WEAKER COMPARED TO YESTERDAYS MODEL RUNS...WHICH A...FACILITATES DECREASED POPS NEXT WEEK...AND B...INCREASED HIGH TEMPS...BOTH OF WHICH WERE IMPLEMENTED WITH THIS FORECAST PACKAGE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1243 AM CDT THU AUG 15 2013 SCATTERED TSRA FROM NEAR IEN THROUGH AIA CONTINE TO DROP SOUTHEAST. FOR THE KLBF TAF SITE CONFIDENCE IS TOO LOW TO INCLUDE TSRA...BUT WILL BE MONITORED CLOSELY FOR INCLUSION BY NEXT TAF ISSUANCE. AS FOR KVTN...STORMS TO CROSS WESTERN CHERRY COUNTY...BUT SHOULD PASS SOUTHWEST OF KVTN TAF LOCATION. LOW CLOUDS ALREADY IN KVTN AREA. SREF PROBS AND EARLIER HRRR SUGGESTS VSBYS SHOULD TEMPORARILY GO DOWN TO IFR AFTER 08Z OR SO NEAR KVTN. ALSO MVFR CIGS AND 5SM BR AT KLBF 09Z-14Z. STORMS DEVELOPMENT EXPECTED IN THE AFTERNOON AT BOTH TAF SITES WITH INCLUSION FOR PROB30 20Z-01Z. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JWS SYNOPSIS...KNUTSVIG SHORT TERM...KNUTSVIG LONG TERM...CLB AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1237 AM CDT THU AUG 15 2013 .UPDATE... ISSUED AT 1237 AM CDT THU AUG 15 2013 POPS HAVE BEEN ADDED/ADJUSTED BASED ON LATEST RADAR TRENDS. AS WITH THE PAST 2 NGTS ANOTHER SMALL MCS IS ORGANIZING OVER THE PANHANDLE. THIS CLUSTER IS NOT ASSOCIATED WITH THE LLJ AND WILL ONLY HAVE ITS OWN COLD POOL TO KEEP IT GOING. NEW SHWRS HAVE DEVELOP FROM JYR UP TO BVN IN THE LAST HR. THESE ARE LLJ RELATED. THE 03Z HI-RES RAP HAS ALL THIS HANDLED WELL SO IT WAS USED AS A FIRST GUESS FOR POPS THRU 12Z. SOME CHANGES IN CLOUD COVER WILL NEED TO BE MADE BEFORE SUNRISE. OTHERWISE...NO CHANGES. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 CLOUDS LINGERED ACROSS MUCH OF THE AREA THIS AFTERNOON AND HAS SO FAR HELPED TO PUT A CAP ON MORE WIDESPREAD CONVECTION. THAT SAID...INSTABILITY IS BEGINNING TO BUILD...AND WITH SOME NOTABLE MOISTURE CONVERGENCE AHEAD OF DEVELOPING CONVECTION TO OUR NORTH...EXPECT THE POTENTIAL FOR ADDITIONAL DEVELOPMENT THROUGH THE LATE AFTERNOON AND EVENING HOURS. MODELS HAVE NOT HAD A GREAT HANDLE ON THIS ALL DAY...ALBEIT 12Z WRF AND LATEST HRRR BOTH ATTEMPTED TO PICK UP ON CONVECTION TO OUR NORTH...TAKING IT SOUTHWARD THROUGH THE EVENING HOURS. WHILE CONFIDENCE IS NOT PARTICULARLY HIGH...CONTINUE TO SEE THE POTENTIAL FOR SOME ADDITIONAL THUNDERSTORM ACTIVITY THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS AS THERE IS PLENTY OF INSTABILITY TO TAP...ESPECIALLY WEST OF HIGHWAY 281. THAT SAID...SHEAR IS VERY WEAK...AND ANY ADDITIONAL STORMS THAT DO DEVELOP ARE NOT EXPECTED TO BE SEVERE OR WIDESPREAD. AS WE WORK TOWARDS THURSDAY MORNING AND FOCUS OF INITIAL CONVECTION SHIFTS SOUTHWARD...COULD SEE SOME PARTIAL CLEARING...AND WITH LIGHT SOUTHEASTERLY WINDS AND ELEVATED LOW LEVEL MOISTURE...DECIDED TO INSERT PATCHY FOG INTO THE FORECAST FOR THE EARLY MORNING HOURS TOMORROW. LATEST HRRR IS INDICATING POSSIBLY SOME DENSE FOG ACROSS OUR NORTH BY 09Z...BUT WITH UNCERTAINTY IN TIMING AND AMOUNT OF CLEARING...PATCHY MENTION SEEMED MORE REASONABLE FOR THE TIME BEING. AS WE WORK INTO THE DAYTIME HOURS THURSDAY...THE POTENTIAL FOR SOME STRONG/MARGINALLY SEVERE STORMS WILL BE REALIZED BY EARLY AFTERNOON AS MODELS ARE PICKING UP ON AN UPPER LEVEL SHORTWAVE DROPPING DOWN FROM THE NORTH COUPLED WITH THE PRESENCE OF A WEAK WARM FRONTAL BOUNDARY DRAPED ACROSS THE LOCAL AREA FROM NORTHWEST TO SOUTHEAST. THIS COMBINATION...WITH PLENTY OF AVAILABLE INSTABILITY...SHOULD MAKE FOR A MORE ACTIVE AFTERNOON AND EVENING...AND CONTINUED WITH MENTION OF POTENTIAL SEVERE WEATHER IN HWO THIS AFTERNOON. WHILE SHEAR IS NOT ALL THAT IMPRESSIVE...CAPE AND FORCING SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF A FEW STORMS WITH MARGINALLY SEVERE HAIL AND THUNDERSTORM WIND GUSTS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 THURSDAY NIGHT THROUGH WEDNESDAY. MAIN FORECAST CONCERNS WILL BE CHANCES FOR THUNDERSTORMS ON AND OFF THROUGH THE PERIOD AND TEMPERATURES. AN UPPER LEVEL WAVE WILL CONTINUE TO MOVE THROUGH THE AREA THURSDAY NIGHT. THUNDERSTORMS WILL CONTINUE ACROSS THE AREA DURING THE EVENING BUT GRADUALLY COME TO AN END FROM NORTHWEST TO SOUTHEAST DURING THE OVERNIGHT HOURS AND INTO FRIDAY MORNING. MUCAPE REMAINS AROUND 3000 J/KG DURING THE EVENING BUT DROPS OFF LATER IN THE NIGHT. ON FRIDAY THE UPPER LEVEL RIDGE IN THE ROCKIES STARTS TO SLIDE TO THE EAST AND WITH THE RAIN MOVING OUT...TEMPERATURES WILL WARM SOME. FRIDAY NIGHT INTO SUNDAY THE UPPER LEVEL RIDGE BUILDS ACROSS THE AREA AND EXPECT DRY CONDITIONS AND TEMPERATURES WILL CONTINUE TO WARM A FEW DEGREES. AN UPPER LEVEL WAVE WILL MOVE OVER THE RIDGE SUNDAY NIGHT AND BRING A SMALL CHANCE FOR THUNDERSTORMS. THERE SHOULD BE A BRIEF BREAK FROM THUNDERSTORMS AGAIN ON MONDAY BUT ANOTHER UPPER LEVEL WAVE MOVES INTO THE AREA MONDAY NIGHT AND TUESDAY. THERE IS ALSO A WEAK COLD FRONT THAT MOVES THROUGH THE FORECAST AREA MONDAY NIGHT. THUNDERSTORMS ARE EXPECTED ALONG AND BEHIND THE COLD FRONT. DESPITE THE COLD FRONT TEMPERATURES SHOULD CONTINUE TO WARM A DEGREE OR TWO EACH DAY AS THE UPPER RIDGE SETTLES OVER THE PLAINS. TUESDAY NIGHT AND WEDNESDAY THE MODELS HAVE SOME DIFFERENCES IN THE MAIN PATTERN. THE GFS HAS AN UPPER RIDGE...WHILE THE ECMWF HAS A TROUGH MOVING THROUGH. WILL HAVE A SMALL CHANCE FOR THUNDERSTORMS FOR NOW. THE TEMPERATURE SHOULD REMAIN ABOVE NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1237 AM CDT THU AUG 15 2013 REST OF TNGT: REMOVED FOG AND LOW CIGS FROM THE TAF BASED ON LBF/OAX SOUNDINGS AS WELL AS WIND AND DWPT TRENDS FROM YESTERDAY AFTN. EXPECT VFR CIGS MAY GO SCT AT TIMES. THERE IS A CLUSTER OF TSTMS OVER THE NEB PANHANDLE THAT WILL NEED TO BE MONITORED FOR POSSIBLE INSERTION INTO THE TAF TOWARD DAWN. S WINDS UNDER 10 KTS. THU: LOW-END VFR CIGS SHOULD INCREASE TO MID-LVL CIGS FROM THE REMNANTS OF NEARBY TSTM CLUSTER. BY 18Z...CURRENT EXPECTATION IS FOR SCT VFR CU TO DEVELOP WITH CB POSSIBLE AFTER 21Z. THERE IS A LOW PROBABILITY FOR 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES A DIRECT HIT FROM AN AFTN OR EVNG TSTM. S WINDS LESS THAN 10 KTS WILL BACK TO SE. THU EVNG: TSTM THREAT SHOULD BE OVER BY 03Z. WE ARE SEEING SIGNALS OF POSSIBLE IFR FOG AFTER 06Z. CIG CONFIDENCE: MEDIUM VSBY CONFIDENCE: HIGH WIND CONFIDENCE: HIGH WX CONFIDENCE: MEDIUM && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...SAR LONG TERM...JCB AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
300 AM PDT THU AUG 15 2013 .SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION. TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER. TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO EARLY NEXT WEEK. && .SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25 INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN. .LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES OF THE SOUTHERN SIERRA OF INYO COUNTY. ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS. IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO WARM. && .AVIATION...FOR MCCARRAN...SOUTHWEST WINDS THROUGH THIS MORNING BEFORE TURNING TO THE SOUTHEAST AROUND 8-10 KTS AFTER 19Z. THESE SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS AND MORMON MESA CORRIDORS. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST DIRECTION FOR MUCH OF TODAY. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && $$ GORELOW/PIERCE FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1257 AM CDT THU AUG 15 2013 .UPDATE... 06Z AVIATION DISCUSSION UPDATED BELOW. && .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT PRETTY QUIET ACROSS THE CWA THIS AFTERNOON BUT WILL BE WATCHING THE WESTERN CWA OVER THE NEXT FEW HOURS FOR THE POTENTIAL FOR A FEW ISOLD THUNDERSHOWERS AS SHORTWAVE ENERGY APPROACHES FROM THE MIDWEST. BEST SUPPORT DOES NOT ARRIVE UNTIL LATER THIS EVENING...BUT DAYTIME HEATING ACROSS THE WESTERN CWA HAS ALLOWED MLCAPE TO APPROACH 1000 J/KG. SHEAR IS LACKING ONCE AGAIN AS HAS BEEN THE CASE THE PAST FEW DAYS. CURRENTLY SEEING A CONGESTED CU FIELD ACROSS NORTH CENTRAL SD WITH RADAR ECHOES JUST BEGINNING TO INCREASE OVER CORSON COUNTY. HRRR ACTUALLY PICKING UP ON THIS AND SHOWING A FEW POPCORN TYPE LIGHT SHOWERS OR MAYBE A MODERATE THUNDERSHOWER THROUGH LATE AFTERNOON. WILL MAINTAIN SLIGHT CHANCE POPS FOR THE WESTERN CWA THROUGH THE AFTERNOON. MAIN SHORTWAVE ENERGY APPROACHES THE REGION LATER THIS EVENING...BUT MODELS NOT TOO IMPRESSED WITH THIS FOR OUR CWA. 12Z NSSL WRF SHOWS A LINE OF SHOWERS AND STORMS MOVING INTO WESTERN SD LATER THIS EVENING BUT DIES OUT AS ITS ENTERING THE WESTERN CWA. WILL MAINTAIN SMALL POPS OVERNIGHT AS WELL...BUT HAVE TRIMMED THINGS DOWN TO DRY FOR THE EASTERN CWA AS THERE JUST DOESNT SEEM TO BE ANY SUPPORT FOR PRECIP. THERE REALLY IS NO LOW LEVEL JET TO SPEAK OF OVERNIGHT EITHER. WEAK SHORTWAVE ENERGY MOVES SOUTHEAST OVER THE AREA ON THURSDAY BUT MODELS KEEP TRENDING DRIER AND DRIER FOR THIS...TO THE POINT NOW WHERE MOST MODELS ARENT EVEN SHOWING ANY PRECIP FOR THE AREA. HAVE SCALED BACK POPS QUITE A BIT...GOING DRY IN PLACES BUT KEEPING A SLIGHT CHANCE GOING FOR MOST PLACES. AFTER THURSDAY...THE WARM UP BEGINS AS UPPER RIDGING BUILDS OVER THE HIGH PLAINS AND DAKOTAS. .LONG TERM...SATURDAY THROUGH WEDNESDAY MAIN CHALLENGE IN THE LONG TERM WILL BE PRECIP CHANCES UNDER THE DOMINANT UPPER RIDGE. MODELS ARE NOT IN GOOD AGREEMENT TODAY IN THE EXTENDED. TOSSED OUT THE GEM AS IT IS THE ONLY MODEL SHOWING A DEVELOPING TROPICAL SYSTEM IN THE GULF THIS WEEKEND. THIS MAY CONTAMINATE QPF AND PRESSURE FIELDS ALL THE WAY NORTH INTO THE DAKOTAS. GFS AND ECMWF ARE BOTH FLIP FLOPPING WITH MOISTURE FIELDS THOUGH SFC PRESSURE PROGS ARE SIMILAR. BOTH MODELS SHOW TWO TROFS MOVING ACROSS THE DAKOTAS...ONE SUNDAY NIGHT/MONDAY AND ANOTHER TUESDAY NIGHT/WEDNESDAY. HOWEVER THE GFS IS WET FOR THE FIRST AND DRY FOR THE SECOND WHILE THE ECMWF IS OPPOSITE. STUCK WITH ALLBLEND POPS SUNDAY NIGHT/MONDAY AS 30S/40S SEEM REASONABLE AT THIS POINT. WENT DRIER THAN ALLBLEND FOR THE END OF THE PERIOD BASED ON INTER OFFICE COLLABORATION. TEMPERATURES SHOULD BE ON THE RISE THROUGH THE PERIOD WITH HIGHS IN THE UPPER 80S TO LOWER 90S EXPECTED. && .AVIATION... 06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS FAIRLY TRANQUIL VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE LOCAL TERMINALS AS THE REGION REMAINS BETWEEN HIGH PRESSURE TO THE EAST AND LOW PRESSURE TO THE WEST. LIGHT SOUTH TO SOUTHEAST WINDS CAN BE EXPECTED TONIGHT INTO THURSDAY. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE OVER/NEAR THE WESTERN TAF SITES LATE TONIGHT. A TEMPORARY MVFR/IFR FOG/STRATUS CONDITION IS POSSIBLE AT ANY OF THE FOUR TERMINALS BY LATE TONIGHT INTO THURSDAY MORNING...AS LOW LEVEL MOISTURE STEADILY INCREASES ACROSS THE REGION. BY LATE THURSDAY MORNING...VFR CONDITIONS SHOULD BE RETURNING OR ONGOING AT ALL TERMINALS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR SHORT TERM...TMT LONG TERM...WISE AVIATION...MOHR WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 PM CDT WED AUG 14 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 333 PM CDT WED AUG 14 2013 AT 3 PM...THE SATELLITE LOOP SHOWED A BROKEN DECK OF 7 TO 8K FOOT CLOUDS ACROSS THE FORECAST AREA. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THESE CLOUDS AND THEY SHOW THAT THESE CLOUDS WILL GRADUALLY DISSIPATE THIS EVENING. FOR LATE TONIGHT AND THURSDAY MORNING...THE BUFKIT SOUNDINGS SHOW THAT THERE WILL BE A DEEP LAYER /UP TO 775 MB/ OF LIGHT WINDS ACROSS THE AREA. WHILE THIS WOULD BE FAVORABLE FOR THE DEVELOPMENT OF VALLEY FOG. THE NAM/WRF...GFS...AND RAP CONTINUE TO SHOW THAT THE TEMPERATURE/DEW POINT SPREAD WILL REMAIN AT OR ABOVE 1C. IN ADDITION...THE GFS AND NAM/WRF SUGGEST THAT THERE COULD BE STILL SOME CLOUDS AROUND THE REGION. AS A RESULT...WENT WITH PATCHY VALLEY FOG FOR THE MISSISSIPPI RIVER AND ITS TRIBUTARIES...AND AREAS OF FOG IN THE WISCONSIN RIVER VALLEY. ON THURSDAY...THE MODELS CONTINUE TO SHOW THAT A SHORT WAVE TROUGH WILL MOVE SOUTHEAST ACROSS SOUTHERN AND WESTERN IOWA. WEAK 925 AND 850 MB MOISTURE TRANSPORT NORTHEAST OF THIS SYSTEM WILL AID IN THE DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS NORTHEAST IOWA...SOUTHEAST MINNESOTA...AND SOUTHWEST WISCONSIN. WITH ML CAPES LESS THAN 400 J/KG AND VERY WEAK 0-3 KM AND 0-6 KM...NONE OF THESE THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 333 PM CDT WED AUG 14 2013 ON FRIDAY...THE 925 MB AND 850 MB WEAK MOISTURE TRANSPORT AND 700 TO 600 MB FRONTOGENESIS REMAINS SOUTHWEST OF THE FORECAST AREA. IN ADDITION...THERE IS VERY LITTLE SURFACE MOISTURE CONVERGENCE ACROSS THE AREA. WITH THE MESO MODELS IN AGREEMENT WITH THE GEM AND ECMWF THAT THE AREA WILL REMAIN DRY...REMOVED THE PRECIPITATION CHANCES FOR THIS TIME PERIOD. ON BOTH THURSDAY AND FRIDAY NIGHTS...BOTH THE GFS AND NAM/WRF SOUNDINGS SHOW A DEEP LAYER /UP TO AT LEAST 800 MB/ OF LIGHT WINDS. THIS WOULD BE VERY FAVORABLE FOR THE DEVELOPMENT OF VALLEY FOG. HOWEVER THEY ALSO HINT THAT THERE MAY BE SOME CLOUDS AROUND THE REGION. ANOTHER FACTOR THAT MAY BE A LIMITING FACTOR IS THE AMOUNT OF MOISTURE IN THE BOUNDARY LAYER. THE NAM/WRF HAS MUCH MORE MOISTURE THAN THE GFS. DUE TO THIS UNCERTAINTY...JUST INTRODUCED PATCHY TO AREAS OF VALLEY FOG ON BOTH NIGHTS. FROM MONDAY THROUGH WEDNESDAY...THE MODELS ARE CONTINUING TO STRUGGLE WITH THE 500 MB UPPER AIR PATTERN. THE GFS AND GEM ARE SHOWING THAT THE UPPER LEVEL RIDGE REMAINS LONGER TO THE WEST THAN THE ECMWF. AS A RESULT...THE GFS AND GEM ARE FASTER AT MOVING THE COLD FRONT SOUTHEAST INTO THE FORECAST AREA. MEANWHILE THE ECMWF HAS THE FRONT REMAINING WELL NORTHWEST OF THE FORECAST AREA. SINCE THE MODELS HAVE BEEN TRENDING SLOWER DURING THIS TIME PERIOD...THE CONSENSUS OF OUR OFFICE AND THE SURROUNDING WFOS TO KEEP MOST OF THE FORECAST AREA DRY DURING THIS TIME FRAME. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1130 PM CDT WED AUG 14 2013 THE VALLEY FOG FORECAST FOR THIS MORNING AT LSE REMAINS PROBLEMATIC. THE WIND FIELD IS VERY FAVORABLE FOR VALLEY FOG...BUT SCT-OVC HIGH BASED CUMULUS PERSISTS WHICH HAS KEPT THE TEMPERATURE/DEWPOINT SPREAD JUST SLIGHTLY HIGHER THAN IDEAL. WITH VARIOUS MODELS SUCH AS THE RAP...GFS AND NAM CONTINUING TO INDICATE THE CLOUDS GOING NOWHERE...THINK ANY VALLEY FOG WILL OCCUR MORE AWAY FROM THE AIRPORT IN THE NARROWER VALLEYS...AND POSSIBLY THE NARROWER SECTION OF THE MISSISSIPPI SOUTH OF LA CROSSE. HAVE PLAYED THE FOG WITH A VCFG AND SCT003...BUT SHOULD THE CLOUDS CLEAR EARLY THIS MORNING...MORE FOG AND LOWER VISIBILITIES WILL BE REQUIRED. OTHERWISE...THESE HIGH BASED CUMULUS CLOUDS OF A SCT-BKN VARIETY SHOULD PERSIST THROUGH THE TAF PERIOD UNDER A LIGHT SURFACE WIND REGIME. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
950 AM CDT THU AUG 15 2013 .DISCUSSION... 949 AM CDT VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE. MTF && .PREV DISCUSSION... 247 AM CDT NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST. LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE. LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES. TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70 DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S. FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT SIMILAR CONDITIONS SATURDAY. SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE APPROACHES. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * WEAK LAKE BREEZE TO DEVELOP EARLY AFTERNOON AND MOVE INLAND TO REACH ORD AND MDW MID TO LATE AFTERNOON FLIPPING LIGHT WINDS TO OUT OF THE E-SE. TRS //DISCUSSION...UPDATED 12Z... HIGH PRESSURE OVER THE REGION WILL CONTINUE THE QUIET VFR CONDITIONS. THE WEAK GRADIENT AND VERY LIGHT WINDS ALOFT SHOULD ALLOW FOR ANOTHER LAKE BREEZE TO DEVELOP AND PUSH INLAND DURING THE AFTERNOON. FAIRLY DENSE CIRRUS SHIELD OVERHEAD COULD SUPPRESS WARMING A BIT AND INITIALLY SLOW THE PROGRESSION OF THE LAKE BREEZE...SO THE EASTERLY WIND SHIFT AT ORD AND MDW COULD BE A BIT LATER IN THE AFTERNOON THAN ON WEDNESDAY AND THE BOUNDARY MAY NOT PUSH THROUGH DPA. ONCE THE SHIFT TO EAST WINDS OCCURS AT ORD AND MDW...SPEEDS SHOULD AGAIN BE MAINLY UNDER 10 KT...EXCEPT POSSIBLY SHORTLY AFTER THE LAKE BREEZE PASSAGE. SCT TO BKN VFR CU WILL DEVELOP UNDER THE CIRRUS SHIELD BEFORE CLEARING THIS EVENING. LIGHT AND VRB TO CALM WINDS AGAIN TONIGHT WILL BECOME LIGHT NORTHEAST MID TOMORROW MORNING BEFORE FLOPPING OVER TO EAST BY EARLY AFTERNOON. RC //ORD AND MDW CONFIDENCE...UPDATED 14Z... * MEDIUM ON WEAK LAKE BREEZE REACHING ORD AND MDW MID TO LATE AFTERNOON. * HIGH ON PREVAILING SPEED REMAINS BELOW 10 KT THROUGH THE DAY. TRS //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH MONDAY...VFR. TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND WEDNESDAY. RC && .MARINE... 316 AM CDT EXPANSIVE HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER PATTERN ACROSS THE LAKE THROUGH THE WEEKEND. MODESTLY STRONG SOUTHWEST WINDS OVER THE NORTH HALF EARLY THIS MORNING WILL SHIFT WEST AND THEN RETURN TO SOUTHWEST THIS AFTERNOON WHILE DIMINISHING. THE SOUTH HALF COULD SEE A BRIEF PERIOD THIS MORNING WHEN WINDS SHIFT WEST AND GUST TO 20 KT BUT OTHERWISE SOUTHWEST WINDS 15 KT OR LESS WILL DIMINISH FURTHER TONIGHT. THEREAFTER...THE NORTH HALF WILL SEE AN EXTENDED PERIOD OF SOUTHWEST WINDS OF 15 KT OR LESS AND THE SOUTH 10 KT OR LESS WITH PERIODS OF VARIABLE WINDS UNTIL SUNDAY WHEN HIGH PRESSURE FINALLY SHIFTS EAST. AS LOW PRESSURE TAKES SHAPE ACROSS THE CANADIAN PRAIRIES AND PUSHES EAST SUNDAY NIGHT INTO MONDAY...THE TIGHTER PRESSURE GRADIENT...ESPECIALLY OVER THE NORTH HALF...WILL RESULT IN INCREASED SOUTHWEST WINDS. A WARM AIR MASS OVER THE LAKE BY THAT TIME WILL LIKELY LIMIT MIXING AND GUSTS...BUT WINDS TO 25 KT ARE POSSIBLE ACROSS THE FAR NORTH ON MONDAY. RC && .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
NWS HASTINGS NE
653 AM CDT THU AUG 15 2013 .UPDATE... ISSUED AT 652 AM CDT THU AUG 15 2013 NO SUBSTANTIAL CHANGES MADE TO THE FCST...BUT DID MAKE SOME ADJUSTMENTS TO INCREASE SKY AND TIMING/LOCATION ADJUSTMENTS TO POPS. ALSO DECREASED TEMPS THRU EARLY AFTN TU SUPPRESS THE DIURNAL RISE...ACCOUNTING FOR RAIN AND CLOUDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM CDT THU AUG 15 2013 ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY DAYBREAK FRI. SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE... THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO BE NEAR PUB BY SUNSET. FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS. EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED RAINFALL. THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE. THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS. WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA. WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500 J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER CLOUDINESS WHICH WILL RETARD DIURNAL HEATING. OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR /WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/. INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND 20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING SUPERCELL SPLITS A POSSIBILITY. MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1 KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY BOUNDARIES. TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE SKIES CLEAR. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 431 AM CDT THU AUG 15 2013 GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY. BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW 80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT THE LONG TERM FORECAST PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 652 AM CDT THU AUG 15 2013 TODAY: VFR THOUGH WITH POCKETS OF BRIEF IFR VSBY AND MVFR CIGS IN SHWRS/TSTMS THRU 14Z-15Z. WHILE VSBY WILL RETURN TO VFR...THERE COULD BE A PERIOD OF MVFR CIGS AFTER THIS SHWR/TSTM ACTIVITY DEPARTS. THEN A BREAK BEFORE SCT SHWRS/TSTMS REFORM AFTER 20Z. EXPECT POCKETS OF MVFR OR IFR VSBYS. THERE IS A LOW PROBABILITY OF 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES A DIRECT HIT. LIGHT S WINDS WILL EVENTUALLY BACK TO SE. TNGT: TSTM THREAT SHOULD BE OVER BY 03Z. THEN CLEARING WITH POTENTIAL FOR VFR TO DETERIORATE TO IFR FOG AFTER 08Z. WHILE NOT INDICATED IN THE TAF...THERE IS POTENTIAL FOR 1/4SM FG VV001. CIG CONFIDENCE: MEDIUM VSBY CONFIDENCE: LOW IN ANY TSTM AND LATE FOG WIND CONFIDENCE: HIGH WX EXCEPT NEAR ANY TSTMS WX CONFIDENCE: MEDIUM && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
500 AM PDT THU AUG 15 2013 .SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION. TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER. TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO EARLY NEXT WEEK. && .UPDATE...SATELLITE SHOWS MID CLOUDS DEVELOPING AS FAR NORTH AS THE LAS VEGAS VALLEY. TIME HEIGHT/FORECAST SOUNDING FOR LAS VEGAS INDICATE MOISTURE IN THE H7-H5 LAYER PERSISTING THROUGHOUT THE DAY. SO MADE SOME CHANGES TO SKY GRIDS. ALSO...INCREASED POPS ACROSS CENTRAL AND SOUTHERN MOHAVE COUNTY THROUGH 18Z AS RADAR SHOWS ISOLATED LIGHT RAIN SHOWERS CONTINUE TO DEVELOP. PIERCE && .PREV DISCUSSION... 300 AM PDT THU AUG 15 2013 .SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25 INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN. .LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES OF THE SOUTHERN SIERRA OF INYO COUNTY. ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS. IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO WARM. && .AVIATION...FOR MCCARRAN...SOUTHWEST WINDS THROUGH THIS MORNING BEFORE TURNING TO THE SOUTHEAST AROUND 8-10 KTS AFTER 19Z. THESE SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS AND MORMON MESA CORRIDORS. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST DIRECTION FOR MUCH OF TODAY. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && $$ GORELOW/PIERCE FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
944 AM CDT THU AUG 15 2013 .UPDATE... LATEST HRRR IS SUPPORT OF DEVELOPING SOME SHOWER ACTIVITY ACROSS MAINLY OUR SOUTH AND EASTERN AREAS. COLD FRONT THAT MOVED THROUGH A COUPLE OF DAYS AGO IS NOW STALLED OUT JUST NORTH OF THE GULF COAST. SFC TROUGH EXTENDS NORTHWARD THROUGH EASTERN TN. MEANWHILE...SOME MID AND UPPER LEVEL TROUGHING IS NOTED ACROSS THE SOUTHEAST. UPPER LEVEL AXIS TO SET UP JUST WEST OF THE MID STATE. THIS WILL HELP TO KEEP JUST ENOUGH MOISTURE IN PLACE TO WARRANT THE POTENTIAL FOR CONVECTION. FOR THE FCST...CURRENT GRIDS LOOK TO BE IN GOOD SHAPE. CERTAINLY MORE IN THE WAY OF CLOUDINESS CAN BE EXPECTED ACROSS THE EAST AND SOUTH BUT PCLDY CONDITIONS SHOULD HOLD FOR THE MOST PART. ONLY CHANGE WILL BE TO BUMP HIGH TEMPS BY JUST 1 DEGREE OR SO. UPDATE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 708 AM CDT THU AUG 15 2013/ UPDATE...FOR 12Z TAFS... AVIATION... VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD FOR ALL SITES. CHANCE OF SHOWERS WILL INCREASE FROM THE SOUTHEAST THIS AFTERNOON...INTRODUCING VCSH AT CSV AROUND 00Z. BEST MOISTURE WILL LIKELY REMAIN IN THE SOUTHERN AND EASTERN PORTIONS OF THE AREA...SO KEPT PRECIP OUT OF CKV AND BNA FOR NOW. PREV DISCUSSION... /ISSUED 323 AM CDT THU AUG 15 2013/ DISCUSSION...IT WAS AN UNUSUALLY COOL MORNING ACROSS THE MID STATE WITH TEMPERATURES MOSTLY IN THE 50S. THE DRY AIR AND NEAR RECORD COOL CONDITIONS WERE ASSOCIATED WITH A SURFACE HIGH PRESSURE SYSTEM CENTERED OVER THE OHIO VALLEY. THIS BREAK FROM SUMMER IS VERY TEMPORARY...AS DEEP MOISTURE SITTING SOUTHEAST OF OUR AREA IS SET TO PUSH INTO THE MID STATE OVER THE NEXT COUPLE OF DAYS. MODELS ARE IN PRETTY GOOD AGREEMENT WITH A DEVELOPING MID/UPPER TROUGH OVER THE MID MS AND TN VALLEY REGIONS OVER THE NEXT COUPLE OF DAYS. AS THIS TROUGH DEVELOPS...AN INVERTED SURFACE TROUGH OVER THE PLATEAU WILL INTENSIFY SLIGHTLY AND PULL WESTWARD...BRINGING DEEPER MOISTURE ACROSS THE MID STATE. THIS WILL SET THE STAGE FOR SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. THE FIRST CHANCE FOR RAIN WILL DEVELOP OVER OUR SOUTHEAST COUNTIES THIS AFTERNOON...JUST A 30 PERCENT CHANCE FOR SHOWERS. THE CHANCE FOR SHOWERS WILL SPREAD ACROSS THE AREA TONIGHT INTO FRIDAY. ENOUGH INSTABILITY WILL DEVELOP FOR ISOLATED THUNDERSTORM POTENTIAL FRIDAY AFTERNOON. THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE INTO SATURDAY AS THE UPPER TROUGH ADVANCES. WE ARE EXPECTING A PRETTY GOOD CHANCE FOR SHOWERS...BUT NOT A TOTAL WASHOUT. THE COVERAGE OF SHOWERS WILL DIMINISH SATURDAY NIGHT...THEN INCREASE AGAIN WITH DIURNAL INFLUENCES ON SUNDAY. NO ORGANIZED OR WIDESPREAD SEVERE WX OR EXCESSIVE RAINFALL IS EXPECTED THROUGH THIS FORECAST PERIOD. BEYOND SUNDAY... THE TROUGH LIFTS OUT AND HEIGHTS BUILD ACROSS THE REGION. A BERMUDA HIGH PATTERN DEVELOPS WITH TEMPERATURES AND HUMIDITY LEVELS CLIMBING BACK TO TYPICAL SUMMER LEVELS. THERE WILL BE GENERALLY SMALL CHANCES FOR DIURNALLY DRIVEN CONVECTION. 13 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
220 PM CDT THU AUG 15 2013 .DISCUSSION... 949 AM CDT VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE. MTF //PREV DISCUSSION... 247 AM CDT NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST. LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE. LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES. TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70 DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S. FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT SIMILAR CONDITIONS SATURDAY. SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE APPROACHES. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * NONE. //DISCUSSION...UPDATED 18Z... HIGH PRESSURE STRETCHING FROM THE MID MS VALLEY E TO THE DELMARVA PENINSULA IS FORECASTED TO REMAIN OVER/VERY NEAR THE LOCAL AREA THROUGH FRI...AND BEYOND. RESULT IS LIGHT WINDS THROUGH THE FORECAST PERIOD...AND VERY LIGHT TO CALM TONIGHT INTO FRI MORNING. WITH ONLY A SMALL DIFFERENCE IN SURFACE TEMPERATURES BETWEEN LAND AND WATER ONLY EXPECT A WEAK LAKE BREEZE WITH VERY LITTLE MOMENTUM TO PUSH IT VERY FAR INLAND. WINDS WILL REMAIN LIGHT WHETHER THE LAKE BREEZE EVENTUALLY MAKES IT TO ORD OR MDW OR NOT DURING THE REMAINDER OF THE DAY. AN AREA OF CLODS AROUND 080 IS ASSOCIATED WITH A SHORT WAVE CURRENTLY MOVING SE OVER THE IA- MO BOARDER WILL BE DECREASING AS THE DISTURBANCE MOVES FURTHER AWAY DURING THE AFTERNOON. TRS //ORD AND MDW CONFIDENCE...UPDATED 18Z... HIGH ALL ELEMENTS EXCEPT FOR DIRECTION OF THE LIGHT WINDS. TRS //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH MONDAY...VFR. TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND WEDNESDAY. RC && .MARINE... 218 PM CDT TRANQUIL CONDITIONS WILL CONTINUE OVER LAKE MICHIGAN THROUGH THE WEEKEND. VARIABLE WINDS WILL BE SEEN AT TIMES ACROSS THE SOUTHERN THIRD OF THE LAKE AS THE CANADIAN HIGH PRESSURE IN PLACE WILL HAVE THE GREATEST INFLUENCE THERE...WITH REGIONAL LAKE BREEZES EACH AFTERNOON AROUND THE LAKE PERIPHERY. SOUTHERLY WINDS WILL GRADUALLY INCREASE ACROSS THE NORTHERN PART OF THE LAKE LATE IN THE WEEKEND AND THEN EXPAND THEIR WAY SOUTHWARD EARLY NEXT WEEK AS THE HIGH DEPARTS TO THE MID-ATLANTIC. 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
NWS CHICAGO/ROMEOVILLE IL
108 PM CDT THU AUG 15 2013 .DISCUSSION... 949 AM CDT VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE. MTF //PREV DISCUSSION... 247 AM CDT NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST. LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE. LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES. TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70 DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S. FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT SIMILAR CONDITIONS SATURDAY. SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE APPROACHES. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * NONE. //DISCUSSION...UPDATED 18Z... HIGH PRESSURE STRETCHING FROM THE MID MS VALLEY E TO THE DELMARVA PENINSULA IS FORECASTED TO REMAIN OVER/VERY NEAR THE LOCAL AREA THROUGH FRI...AND BEYOND. RESULT IS LIGHT WINDS THROUGH THE FORECAST PERIOD...AND VERY LIGHT TO CALM TONIGHT INTO FRI MORNING. WITH ONLY A SMALL DIFFERENCE IN SURFACE TEMPERATURES BETWEEN LAND AND WATER ONLY EXPECT A WEAK LAKE BREEZE WITH VERY LITTLE MOMENTUM TO PUSH IT VERY FAR INLAND. WINDS WILL REMAIN LIGHT WHETHER THE LAKE BREEZE EVENTUALLY MAKES IT TO ORD OR MDW OR NOT DURING THE REMAINDER OF THE DAY. AN AREA OF CLODS AROUND 080 IS ASSOCIATED WITH A SHORT WAVE CURRENTLY MOVING SE OVER THE IA- MO BOARDER WILL BE DECREASING AS THE DISTURBANCE MOVES FURTHER AWAY DURING THE AFTERNOON. TRS //ORD AND MDW CONFIDENCE...UPDATED 18Z... HIGH ALL ELEMENTS EXCEPT FOR DIRECTION OF THE LIGHT WINDS. TRS //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH MONDAY...VFR. TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND WEDNESDAY. RC && .MARINE... 316 AM CDT EXPANSIVE HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER PATTERN ACROSS THE LAKE THROUGH THE WEEKEND. MODESTLY STRONG SOUTHWEST WINDS OVER THE NORTH HALF EARLY THIS MORNING WILL SHIFT WEST AND THEN RETURN TO SOUTHWEST THIS AFTERNOON WHILE DIMINISHING. THE SOUTH HALF COULD SEE A BRIEF PERIOD THIS MORNING WHEN WINDS SHIFT WEST AND GUST TO 20 KT BUT OTHERWISE SOUTHWEST WINDS 15 KT OR LESS WILL DIMINISH FURTHER TONIGHT. THEREAFTER...THE NORTH HALF WILL SEE AN EXTENDED PERIOD OF SOUTHWEST WINDS OF 15 KT OR LESS AND THE SOUTH 10 KT OR LESS WITH PERIODS OF VARIABLE WINDS UNTIL SUNDAY WHEN HIGH PRESSURE FINALLY SHIFTS EAST. AS LOW PRESSURE TAKES SHAPE ACROSS THE CANADIAN PRAIRIES AND PUSHES EAST SUNDAY NIGHT INTO MONDAY...THE TIGHTER PRESSURE GRADIENT...ESPECIALLY OVER THE NORTH HALF...WILL RESULT IN INCREASED SOUTHWEST WINDS. A WARM AIR MASS OVER THE LAKE BY THAT TIME WILL LIKELY LIMIT MIXING AND GUSTS...BUT WINDS TO 25 KT ARE POSSIBLE ACROSS THE FAR NORTH ON MONDAY. RC && .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
NWS TWIN CITIES/CHANHASSEN MN
417 PM CDT THU AUG 15 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 339 PM CDT THU AUG 15 2013 MAIN FORECAST CHALLENGE IN THE SHORT TERM IS CLOUD COVER AND THE POSSIBILITY OF ANY LIGHT SHRA/SPRINKLES THROUGH EARLY THIS EVENING. OTHERWISE... QUIET WEATHER WILL CONTINUE TO BE THE THEME THROUGH FRIDAY AS WE CONTINUE TO SLOWLY WARM WITH THE BUILDING UPPER RIDGE. LATEST WATER VAPOR IMAGERY AND RAP UPPER AIR ANALYSES SHOWS THE ALL TOO FAMILIAR PATTERN OF THE UPPER RIDGE TO OUR WEST AND UPPER TROUGH TO OUR EAST. HOWEVER... FINALLY STARTING TO SEE SOME CHANGE IN THIS... WHICH WILL GET FURTHER ACCELERATED NEXT WEEK AS RIDGE BROADENS AND FLATTENS OVER THE CONUS AND EXERTS ITS MAIN PROMINENCE OVER THE CENTER PART OF THE COUNTRY. IN THE MEANTIME... WE COULD SEE SOME SHRA AND/OR SPRINKLES THROUGH EARLY THIS EVENING AS SOME LINGERING LOW LEVEL INSTABILITY HELPS PRODUCE SOME TCU WITH PERHAPS SOME PCPN MANAGING TO FALL OUT OF IT. WE WILL BEGIN TO GET INTO RETURN FLOW ON FRIDAY AS THE SURFACE HIGH MOVES INTO THE EASTERN GREAT LAKES... BUT ANY MEANINGFUL WARM ADVECTION WILL WAIT UNTIL BEYOND THAT POINT. FRIDAY SHOULD BE SIMILAR... BUT SLIGHTLY WARMER... THAN TODAY WITHOUT ANY SHRA/SPRINKLE CHANCE AS WARMER AIR ALOFT AND ASSOCIATED SUBSIDENCE WORK INTO THE AREA. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 339 PM CDT THU AUG 15 2013 MORE SUMMERLIKE PATTERN TAKES HOLD LATE IN THE WEEKEND AND LINGERS THROUGHOUT THE WEEK. THE UPPER RIDGE OVER THE PLAINS CONTINUES TO GRADUALLY EXPAND EASTWARD FRIDAY NIGHT THROUGH THE UPCOMING WEEKEND. A DRY AND WARMING PATTERN IS EXPECTED OVER THE NEXT SEVEN DAYS. SOME OF THE GUIDANCE DOES MANAGE TO GENERATE LIGHT PRECIPITATION NEAR THEN MN/SD BORDER OVER THE WEEKEND ALONG A DIFFUSE MID LEVEL BOUNDARY. THE MOISTURE MIGHT BE A BIT OVERDONE SO WILL CONTINUE TO LEAVE DRY MENTION. BY SUNDAY...HIGHS WILL BE ABOVE CLIMATE NORMALS WITH TEMPS IN THE 80S. AS MENTIONED IN OUR DISCUSSION YESTERDAY...THE CENTRAL ATLANTIC RIDGE IS EXPECTED TO DRIFT SOUTHWEST WITH TIME. THE ENSM FORECAST SUPPORTS THIS WITH KEEPING POSITIVE HEIGHT ANOMALIES FARTHER SOUTH THROUGH THE END OF THE MONTH. THIS DISPLACEMENT OF THE ATLANTIC RIDGE WILL ALLOW THE PERSISTENT EAST COAST TROUGH /OUR LOCAL NORTHWEST FLOW/ A CHANCE TO SHIFT EAST. THE MODELS COMING INTO MUCH BETTER AGREEMENT IN THE EXTENDED. WHILE THE RIDGE DOES BECOME FLATTER EARLY NEXT WEEK AS A SERIES OF SHORTWAVES TRACK JUST NORTH OF THE CANADIAN BORDER. A BOUNDARY APPROACHES THE REGION ON MONDAY...BUT ALL MODELS DISSOLVE THIS FEATURE NORTHWEST OF THE FORECAST AREA. THE OPERATIONAL GFS AND TO SOME DEGREE THE ECMWF SHOW THE A GLIMPSE OF THE WARMING TREND THIS WEEKEND WITH 80S...BUT THE WARM UP BEGINS IN EARNEST EARLY NEXT WEEK. 850 MB TEMPS GET BACK UP INTO THE UPPER TEENS AND LOWER 20S. GIVEN THE DRY ANTECEDENT CONDITIONS AND EXPECTED BUILDING RIDGE...MID TO UPPER 80S SEEM EASILY OBTAINABLE NEXT WEEK...AND WE SHOULD ONCE AGAIN SEE 90 DEGREES FOR THE FIRST TIME IN OVER A MONTH. MIXING TO 850-750 MB WITH A SLIGHT SUPER ADIABATIC LAYER GIVES NEAR RECORD TEMPS OF 95-99 DEGREES. SO...WE WILL NEED TO MONITOR THE TEMP ADVECTION AND MIXING POTENTIAL. CLOUD COVER ASIDE...THIS HAS A CHANCE TO BE A HOT STRETCH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1210 PM CDT THU AUG 15 2013 BENIGN AVIATION CONDITIONS WILL CONTINUE THROUGH THE UPCOMING FORECAST PERIOD AS HIGH PRESSURE AT THE SURFACE DRIFTS ACROSS THE AREA WHILE A RIDGE OF HIGH PRESSURE ALOFT CONTINUES TO SLOWLY BUILD INTO THE UPPER MIDWEST. VFR FLIGHT CONDITIONS ARE EXPECTED ALONG WITH LIGHT SOUTHERLY WINDS. THERE IS A SLIGHT POSSIBILITY FOR A SHOWER THIS AFTERNOON INTO EARLY EVENING... BEFORE 03Z... DUE TO SOME MARGINAL INSTABILITY. HOWEVER... ANY ACTIVITY WILL BE VERY ISOLATED AND SHOULDN/T HAVE AN IMPACT ON FLIGHT CONDITIONS GIVEN THE HIGH CLOUD BASES AND LIGHTNESS OF ANY PCPN. WITH THE SLIM CHANCE AND LACK OF EXPECTED IMPACT TO CEILINGS AND VISIBILITIES... KEPT THE MENTION OF ANYTHING OUT OF THE FORECASTS. SHOULD SOMETHING POP UP... AND AMENDMENT COULD BE ISSUED. KMSP...TAF REFLECTS EXPECTATIONS WITH LITTLE IN THE WAY OF UNCERTAINTY OUTSIDE OF THE SLIM CHANCE OF A SHRA AS MENTIONED ABOVE. /OUTLOOK FOR KMSP/ FRIDAY NIGHT THROUGH MONDAY NIGHT...VFR CONDITIONS EXPECTED. SOUTH WIND 5 TO 15 KT THROUGH SATURDAY NIGHT... BECOMING SOUTHWEST 10 TO 20 KT SUNDAY THROUGH MONDAY NIGHT... WITH SPEEDS GENERALLY ON THE LOW END OF THE RANGE AT NIGHT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CLF LONG TERM...TRH AVIATION...JPC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
333 PM CDT THU AUG 15 2013 .SYNOPSIS... ISSUED AT 333 PM CDT THU AUG 15 2013 CURRENTLY...AN UPPER LEVEL DISTURBANCE IS MOVING SOUTH-SOUTHEAST ACROSS SOUTH DAKOTA IN NORTHWEST FLOW ALOFT. AN UPPER LEVEL RIDGE EXTENDS NORTHWARD FROM THE FOUR CORNERS REGION TO SASKATCHEWAN AND AN UPPER LEVEL LOW EXISTS OVER QUEBEC. A SURFACE BOUNDARY CURRENTLY EXTENDS NORTHWESTWARD FROM FRONTIER COUNTY THROUGH GARDEN COUNTY AND INTO NORTHWESTERN NEBRASKA. ALSO...LOW CLOUDS HAVE BEEN PERSISTENT OVER PARTS OF NORTH-CENTRAL NEBRASKA TODAY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 333 PM CDT THU AUG 15 2013 STARTING TO SEE SOME CUMULUS DEVELOPMENT ALONG STATIONARY SURFACE BOUNDARY EXTENDING TO THE NW FROM FRONTIER COUNTY THROUGH OGALLALA AND NWWD. BELIEVE THIS WOULD BE THE BEST AREA FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON...WITH ANY STORMS MOVING SOUTHEASTWARD AT AROUND 20 KTS. MODELS INDICATE 0-6 KM SHEAR OF 30-35 KTS ALTHOUGH SPC MESOANALYSIS DATA IS SHOWING SHEAR UNDER 30 KTS AS OF 20Z. THERE MAY BE A FEW ISOLATED SEVERE STORMS THIS AFTN/EVE...BUT THE BEST CHANCE WOULD BE SOUTH OF I-80. HAVE TRIMMED POPS AND THUNDERSTORM COVERAGE A BIT ACROSS THE AREA TONIGHT BASED ON LATEST MODEL DATA AND TRENDS. HRRR MODEL FROM 18Z HAS A FEW STORMS JUST WEST OF NORTH PLATTE AND AREAS SE...MOVING SE TONIGHT. EMC WRF MODEL HAS A FAIR AMOUNT OF CONVECTION NORTH TO THE SD BORDER HOWEVER...ALTHOUGH ITS NOT AS LIKELY. THUNDERSTORMS SHOULD COME TO AN END IN THE EVENING ACROSS THE AREA AS THE UPPER LEVEL WAVE MOVES THROUGH THE REGION. MODELS ARE POINTING TOWARD MORE FOG AND LOW STRATUS TONIGHT...ESPECIALLY CENTRAL AND EAST. HAVE INCLUDED FOG IN THE FORECAST FOR MOST OF THE AREA. TOMORROW...AFTER LOW CLOUDS AND FOG HAVE DISSIPATED...FAIR SKIES AND TEMPS IN THE MID 70S EAST TO UPPER 80S WEST ARE EXPECTED. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 333 PM CDT THU AUG 15 2013 MID TERM...FRIDAY NIGHT THROUGH SUNDAY...RIDGING WILL CONTINUE TO BUILD ACROSS THE CENTRAL PLAINS FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH TEMPERATURES THE MAIN FORECAST CHALLENGE...FOLLOWED BY PRECIPITATION CHANCES IN THE FAR WEST SUNDAY AFTERNOON. FOR FRIDAY NIGHT...SURFACE HIGH PRESSURE WILL DRIFT EAST INTO THE MIDDLE MISSISSIPPI VALLEY WITH A LEE SIDE TROUGH BEGINNING TO DEEPEN ACROSS THE FRONT RANGES OF COLORADO AND WYOMING. SRLY WINDS WILL BEGIN TO INCREASE LATE FRIDAY IN RESPONSE...AND ARE NOT EXPECTED TO TOTALLY DECOUPLE FRIDAY NIGHT. THIS WILL LEAD TO SLIGHTLY WARMER MIN TEMPS SATURDAY MORNING COMPARED TO FRIDAY MORNING. THE MET AND MAV GUIDANCE ARE IN DECENT AGREEMENT WITH LOWS SATURDAY MORNING SO A BLEND WILL BE UTILIZED...THEN SCALED UPWARD A DEGREE OR TWO DUE TO INCREASED MIXING. MAV AND MET GUIDANCE TEMPS DIVERGE ON SATURDAY...WITH THE MAV 3 TO 6 DEGREES COOLER THAN THE MUCH WARMER MET. UTILIZED THE BIAS CORRECTED CONSALL GUIDANCE FOR HIGHS SATURDAY...WHICH RESULTED IN A COMPROMISE BETWEEN THE MET AND MAV NUMBERS. THIS LED TO HIGHS IN THE MIDDLE 80S IN THE EASTERN CWA...TO THE LOWER 90S IN THE PANHANDLE...WHERE DEW POINTS IN THE LOWER 50S ARE EXPECTED SAT AFTERNOON. FOR SUNDAY...HIGHS WILL MIRROR SATURDAYS FCST...WITH THE EXCEPTION OF THE EASTERN ZONES WHERE SLIGHTLY WARMER TEMPS ARE EXPECTED THANKS TO WARMER H85 AIR. HIGHS SUNDAY WILL RANGE FROM THE UPPER 80S TO LOWER 90S IN THE PANHANDLE AND FAR WEST. BY SUNDAY AFTERNOON...THE LATEST NAM IS HINTING AT BREAKING DOWN THE RIDGE AND INITIATING CONVECTION ACROSS THE PANHANDLE AND FAR WESTERN ZONES LATE SUNDAY AFTERNOON. THE LATEST GFS...KEEPS THIS CONVECTION CONFINED TO THE FRONT RANGES OF COLORADO AND WYOMING...THANKS TO VERY WEAK MID LEVEL STEERING WINDS. INHERITED FCST WAS DRY SUNDAY AFTERNOON...AND INTEND TO KEEP IT THAT WAY...EVEN IN LIGHT OF THE LATEST 12Z NAM SOLN. LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...THERE ARE TWO SCHOOLS OF THOUGHT WITH THE EXTENDED FCST...A...DRY AND VERY WARM CONDS WILL PERSIST WELL INTO THE MIDDLE OF NEXT WEEK-12Z GFS...AND B...A BREAK DOWN IN THE RIDGE ACROSS THE CENTRAL CONUS LEADING TO COOLER AND WETTER CONDS ACROSS THE AREA-ECMWF. GLANCING AT LAST NIGHTS ENSEMBLES...THE MEAN NCEP ENSEMBLE MEAN HAS A BREAKDOWN IN THE WESTERN CONUS RIDGING EARLY IN THE WEEK WITH A FAIRLY ACTIVE PATTERN DEVELOPING BY MIDWEEK. IN CONTRAST...THE OPERATIONAL GFS FROM THIS MORNING HAS A CLOSED LOW OVER THE CENTRAL CA COAST. THE LATTER SOLN...WOULD TEND TO FAVOR A DRY AND WARMER FCST AS RIDGING WILL AMPLIFY DOWNSTREAM OF THE CLOSED CA LOW. NO SURPRISE...THE LATEST MEX GUIDANCE FROM THIS MORNING HAS LOWER TO MIDDLE 90S FOR HIGHS NEXT WEEK WITH DRY CONDS EXPECTED. SINCE THE OPERATIONAL GFS IS KIND OF AN OUTLIER WITH THE ENSEMBLE FCSTS...WILL FAVOR COOLER TEMPS IN THE 80S TO LOWER 90S FOR TEMPS NEXT WEEK. AS FOR PCPN CHANCES...CAN`T SEE MORE THAN A 20 PCT CHANCE TOWARD THE MIDDLE OF NEXT WEEK...AS WEAK DYNAMICS WILL CONTINUE WELL INTO NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1229 PM CDT THU AUG 15 2013 LOW CLOUDS HAVE HUNG IN OVER KVTN TODAY. WITH THE EASTERLY SURFACE WIND...BELIEVE IT WILL CONTINUE TO BE SLOW TO ERODE IN THAT AREA. THE CIG HAS BEEN VARIABLE AT 400 TO 800 FEET...SO IT IS STARTING TO SHOW SIGNS OF LIFTING A BIT. NONETHELESS...BELIEVE BOTH KLBF AND KVTN WILL SEE IFR CONDITIONS LATE TONIGHT WITH FOG/STRATUS FORMING AS INDICATED BY THE BUFR SOUNDINGS/SREF/MOS GUIDANCE. BELIEVE THIS AFTERNOON`S THUNDERSTORMS WILL AFFECT MAINLY KLBF AS STRATUS AT KVTN WILL SLOW WARMING IN THAT AREA. WEST OF KVTN MAY SEE TSRA HOWEVER. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...KNUTSVIG SHORT TERM...KNUTSVIG LONG TERM...CLB AVIATION...KNUTSVIG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1259 PM CDT THU AUG 15 2013 .UPDATE... ISSUED AT 652 AM CDT THU AUG 15 2013 NO SUBSTANTIAL CHANGES MADE TO THE FCST...BUT DID MAKE SOME ADJUSTMENTS TO INCREASE SKY AND TIMING/LOCATION ADJUSTMENTS TO POPS. ALSO DECREASED TEMPS THRU EARLY AFTN TO SUPPRESS THE DIURNAL RISE...ACCOUNTING FOR RAIN AND CLOUDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM CDT THU AUG 15 2013 ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY DAYBREAK FRI. SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE... THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO BE NEAR PUB BY SUNSET. FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS. EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED RAINFALL. THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE. THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS. WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA. WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500 J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER CLOUDINESS WHICH WILL RETARD DIURNAL HEATING. OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR /WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/. INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND 20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING SUPERCELL SPLITS A POSSIBILITY. MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1 KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY BOUNDARIES. TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE SKIES CLEAR. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 431 AM CDT THU AUG 15 2013 GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY. BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW 80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT THE LONG TERM FORECAST PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1250 PM CDT THU AUG 15 2013 WENT WITH A FAIRLY PESSIMISTIC TAF THIS AFTERNOON AS THE LATEST VISIBLE SATELLITE INDICATES IFR STRATUS IS EXPANDING SOUTHWARD. ALREADY HAVE IFR CIGS AT ODX...AND USING EXTRAPOLATION...THIS STRATUS SHOULD REACH KGRI AROUND 19Z. THEREAFTER...CONTINUE TO EXPECT THE POTENTIAL FOR A VCTS LATE THIS AFTERNOON AS CONVECTION ATTEMPTS TO BUILD ACROSS THE LOCAL AREA. HOWEVER...WITH STRATUS AROUND THROUGH THE PEAK HEATING HOURS...DO NOT THINK CONVECTION WILL BE WIDESPREAD NEAR OR NORTH OF THE TERMINAL...AND CONTINUED WITH IMPROVING CIGS TO 4KFT AND ONLY A VCTS THROUGH THE EARLY EVENING HOURS...MORE LIKELY IN RESPONSE TO SHORTWAVE DROPPING SOUTH ACROSS SOUTH DAKOTA THIS AFTERNOON. ONCE SKIES BEGIN TO CLEAR LATE TONIGHT...MODELS ARE INDICATING WE COULD SEE SOME DENSE FOG FORM...AND DID INTRODUCE LIFR CIGS AND VSBYS FOR A FEW HOURS TO ACCOUNT FOR THIS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...SAR
AREA FORECAST DISCUSSION UPDATE
NWS LAS VEGAS NV
1055 AM PDT THU AUG 15 2013 .SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION. TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER. TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO EARLY NEXT WEEK. && .UPDATE...OBSERVATIONS SHOW AN INCREASE IN MOISTURE SOUTH AND EAST OF LAS VEGAS...WITH DEWPOINTS UP APPROXIMATELY 25 DEGREES FROM YESTERDAY MORNING AT LOCATIONS SUCH AS KINGMAN...NEEDLES...AND BULLHEAD CITY. FARTHER NORTH AND WEST...THE VAST MAJORITY OF ANY INCREASE IN MOISTURE IS LIMITED TO A LAYER BETWEEN 700-500MB. NO MAJOR CHANGES WERE NEEDED THIS MORNING...OPTING TO KEEP ANY MENTION OF CONVECTION TODAY LIMITED TO THE HIGHER ELEVATIONS OF EASTERN MOHAVE COUNTY. THE MAIN REASON POPS WERE NOT INCREASED GIVEN THE MOISTURE INCREASE IS A STRONG CAP NEAR 450MB...WHICH IS EXPECTED TO PERSIST THROUGH THE DAY AND SO FAR...BASED ON SATELLITE IMAGERY...IS HOLDING. -KENNEDY- && .PREV DISCUSSION... 300 AM PDT THU AUG 15 2013 .SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25 INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN. .LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES OF THE SOUTHERN SIERRA OF INYO COUNTY. ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS. IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO WARM. && .AVIATION...FOR MCCARRAN...LIGHT WINDS WILL BECOME SOUTHEASTERLY BY EARLY AFTERNOON AROUND 8-10 KTS. THESE SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS AND MORMON MESA CORRIDORS. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST DIRECTION FOR MUCH OF TODAY. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && $$ GORELOW/PIERCE FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
203 PM CDT THU AUG 15 2013 .UPDATE...FOR 18Z TAFS. && .AVIATION... WEAK INVERTED LOW-LEVEL TROUGH SET TO SWING UP INTO THE PLATEAU TODAY...THEN WORK WESTWARD TONIGHT. THIS WILL BEGIN SPREADING DEEPER MOISTURE BACK INTO THE MID-STATE AND EVENTUALLY SHOWERS WILL BEGIN TO DEVELOP...ESPECIALLY AFTER 12Z FRIDAY. INCREASED MOISTURE WILL ALSO MVFR CIGS/VSBYS IN OVERNIGHT. LOW CIGS OVERNIGHT SHOULD IMPROVE AFTER 14-15Z FRI. && .PREV DISCUSSION... /ISSUED 944 AM CDT THU AUG 15 2013/ UPDATE... LATEST HRRR IS SUPPORT OF DEVELOPING SOME SHOWER ACTIVITY ACROSS MAINLY OUR SOUTH AND EASTERN AREAS. COLD FRONT THAT MOVED THROUGH A COUPLE OF DAYS AGO IS NOW STALLED OUT JUST NORTH OF THE GULF COAST. SFC TROUGH EXTENDS NORTHWARD THROUGH EASTERN TN. MEANWHILE...SOME MID AND UPPER LEVEL TROUGHING IS NOTED ACROSS THE SOUTHEAST. UPPER LEVEL AXIS TO SET UP JUST WEST OF THE MID STATE. THIS WILL HELP TO KEEP JUST ENOUGH MOISTURE IN PLACE TO WARRANT THE POTENTIAL FOR CONVECTION. FOR THE FCST...CURRENT GRIDS LOOK TO BE IN GOOD SHAPE. CERTAINLY MORE IN THE WAY OF CLOUDINESS CAN BE EXPECTED ACROSS THE EAST AND SOUTH BUT PCLDY CONDITIONS SHOULD HOLD FOR THE MOST PART. ONLY CHANGE WILL BE TO BUMP HIGH TEMPS BY JUST 1 DEGREE OR SO. UPDATE OUT SHORTLY. PREV DISCUSSION... /ISSUED 708 AM CDT THU AUG 15 2013/ UPDATE...FOR 12Z TAFS... AVIATION... VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD FOR ALL SITES. CHANCE OF SHOWERS WILL INCREASE FROM THE SOUTHEAST THIS AFTERNOON...INTRODUCING VCSH AT CSV AROUND 00Z. BEST MOISTURE WILL LIKELY REMAIN IN THE SOUTHERN AND EASTERN PORTIONS OF THE AREA...SO KEPT PRECIP OUT OF CKV AND BNA FOR NOW. PREV DISCUSSION... /ISSUED 323 AM CDT THU AUG 15 2013/ DISCUSSION...IT WAS AN UNUSUALLY COOL MORNING ACROSS THE MID STATE WITH TEMPERATURES MOSTLY IN THE 50S. THE DRY AIR AND NEAR RECORD COOL CONDITIONS WERE ASSOCIATED WITH A SURFACE HIGH PRESSURE SYSTEM CENTERED OVER THE OHIO VALLEY. THIS BREAK FROM SUMMER IS VERY TEMPORARY...AS DEEP MOISTURE SITTING SOUTHEAST OF OUR AREA IS SET TO PUSH INTO THE MID STATE OVER THE NEXT COUPLE OF DAYS. MODELS ARE IN PRETTY GOOD AGREEMENT WITH A DEVELOPING MID/UPPER TROUGH OVER THE MID MS AND TN VALLEY REGIONS OVER THE NEXT COUPLE OF DAYS. AS THIS TROUGH DEVELOPS...AN INVERTED SURFACE TROUGH OVER THE PLATEAU WILL INTENSIFY SLIGHTLY AND PULL WESTWARD...BRINGING DEEPER MOISTURE ACROSS THE MID STATE. THIS WILL SET THE STAGE FOR SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. THE FIRST CHANCE FOR RAIN WILL DEVELOP OVER OUR SOUTHEAST COUNTIES THIS AFTERNOON...JUST A 30 PERCENT CHANCE FOR SHOWERS. THE CHANCE FOR SHOWERS WILL SPREAD ACROSS THE AREA TONIGHT INTO FRIDAY. ENOUGH INSTABILITY WILL DEVELOP FOR ISOLATED THUNDERSTORM POTENTIAL FRIDAY AFTERNOON. THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE INTO SATURDAY AS THE UPPER TROUGH ADVANCES. WE ARE EXPECTING A PRETTY GOOD CHANCE FOR SHOWERS...BUT NOT A TOTAL WASHOUT. THE COVERAGE OF SHOWERS WILL DIMINISH SATURDAY NIGHT...THEN INCREASE AGAIN WITH DIURNAL INFLUENCES ON SUNDAY. NO ORGANIZED OR WIDESPREAD SEVERE WX OR EXCESSIVE RAINFALL IS EXPECTED THROUGH THIS FORECAST PERIOD. BEYOND SUNDAY... THE TROUGH LIFTS OUT AND HEIGHTS BUILD ACROSS THE REGION. A BERMUDA HIGH PATTERN DEVELOPS WITH TEMPERATURES AND HUMIDITY LEVELS CLIMBING BACK TO TYPICAL SUMMER LEVELS. THERE WILL BE GENERALLY SMALL CHANCES FOR DIURNALLY DRIVEN CONVECTION. 13 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07
AREA FORECAST DISCUSSION
NWS AMARILLO TX
326 PM CDT THU AUG 15 2013 .DISCUSSION... LITTLE OR NO CHANGES TO THE PREVIOUS GRIDS AND FORECAST AS THE WEATHER PATTERN DOES NOT CHANGE MUCH. UPPER HIGH OVER THE FOUR CORNERS AND SOUTHWESTERN STATES THROUGH THE WEEKEND WILL MAINTAIN A NORTHWESTERLY UPPER FLOW TONIGHT...TRANSITIONING TO NORTHERLY BY FRIDAY NIGHT AND SATURDAY. LOOKING AT THE TTU-WRF...NAM...GFS...AND ECMWF...BETTER ORGANIZED CONVECTION COULD POSSIBLY HOLD OFF UNTIL AROUND 00Z FRIDAY OR LATER. THE LATEST HRRR DEVELOPS CONVECTION ACROSS THE NORTHWEST SECTIONS OF THE FORECAST AREA BY 20Z TODAY WHICH THEN MOVES SOUTHEAST ACROSS THE WESTERN AND CENTRAL TEXAS PANHANDLE AROUND 22Z TODAY TO AROUND 00Z TO 02Z FRIDAY. SINCE NOT MUCH DEVELOPING AS OF 20Z TODAY ACROSS THE PANHANDLES...THINKING THAT THE HRRR MAY BE THE ODD MODEL OUT. CONVECTION CURRENTLY OVER OKLAHOMA AND EAST CENTRAL NEW MEXICO MOVING SOUTH AND SOUTHEAST. WILL CONTINUE TO MONITOR TRENDS...BUT WITH CAPES FORECAST TO BE IN THE 1500 TO 2500 J/KG RANGE AND SURFACE DEW POINTS IN THE 60S...CANNOT RULE OUT CONVECTION DEVELOPING PRIOR TO 00Z FRIDAY. AS THE UPPER HIGH BROADENS OVER THE SOUTHWESTERN STATES OVER THE WEEKEND...THE UPPER FLOW TRANSITIONS TO NORTHERLY AND EVEN NORTHEASTERLY BRINGING A GRADUAL END TO THE CONVECTION BY SUNDAY. WARMER AND DRIER CONDITIONS SUNDAY THROUGH NEXT WEDNESDAY WITH HIGHS CLIMBING BACK UP INTO THE 90S. SCHNEIDER && .FIRE WEATHER... AN UPPER RIDGE ACROSS THE FOUR CORNERS REGION AND THE SOUTHWESTERN STATES WILL MAINTAIN A NORTHWESTERLY TO NORTHERLY UPPER FLOW ACROSS THE PANHANDLES THROUGH THE WEEKEND. SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS SOUTHEASTERN AND EASTERN COLORADO AND WESTERN AND SOUTHWESTERN KANSAS LATER TODAY AND TONIGHT AND WILL MOVE SOUTHEAST ACROSS THE PANHANDLES. NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED THROUGH THE MIDDLE OF NEXT WEEK AS MINIMUM AFTERNOON RELATIVE HUMIDITIES REMAIN AT OR ABOVE 20 PERCENT THROUGH THE MIDDLE OF NEXT WEEK. SCHNEIDER && .PRELIMINARY POINT TEMPS/POPS... AMARILLO TX 63 87 62 88 63 / 40 20 20 5 20 BEAVER OK 65 87 64 90 64 / 70 10 5 5 5 BOISE CITY OK 60 89 62 90 62 / 30 10 20 10 20 BORGER TX 66 89 67 90 66 / 50 10 10 5 10 BOYS RANCH TX 63 90 64 92 65 / 30 20 20 10 20 CANYON TX 62 88 61 89 63 / 40 20 20 5 20 CLARENDON TX 65 87 63 87 64 / 60 20 10 5 10 DALHART TX 59 89 62 90 61 / 30 10 20 10 20 GUYMON OK 62 89 64 90 63 / 50 10 10 5 10 HEREFORD TX 61 87 61 88 61 / 30 20 20 5 20 LIPSCOMB TX 63 85 63 87 64 / 70 10 10 5 5 PAMPA TX 63 85 62 86 62 / 50 10 10 5 10 SHAMROCK TX 63 87 62 86 63 / 70 20 10 5 5 WELLINGTON TX 65 88 64 89 65 / 70 20 10 5 5 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 13/11
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1244 PM CDT Thu Aug 15 2013 .UPDATE... Increased POPS this afternoon. && .DISCUSSION... Isolated convection has formed across the Big Country early this afternoon with agitated cumulus increasing in coverage, especially northern and eastern sections. Latest HRRR develops scattered convection across the area this afternoon within a moderately unstable airmass and diminishing CIN. Given latest trends, POPS were increased to 30 percent across the eastern half of the CWA with slight chance elsewhere. Cannot rule out a strong storm or two given an increase in shear aloft and modest instability. The main threat from the stronger storms will be gusty winds with the potential for isolated severe downbursts. Aviation discussion follows. && .AVIATION... Predominantly a VFR forecast the next 24 hours. Scattered showers and thunderstorms will develop across the area this afternoon. Included VCTS at KABI, KJCT and KBBD where better coverage is expected and will monitor convective trends for necessary amendments this afternoon. Any storms will be capable of producing brief MVFR conditions along with gusty winds. A complex of storms may approach the KABI terminal from the north after 06Z tonight but confidence in this scenario is too low to mention at this time. && .PREV DISCUSSION... /ISSUED 625 AM CDT THU AUG 15 2013/ UPDATE... See 12Z aviation discussion below. AVIATION... VFR conditions should prevail across most terminals for most of the day. However, scattered thunderstorms will continue through the period. Given the uncertain timing and location of the storms, not going to mention in the forecast at this time. However, if a storm does pass over a terminal, then a quick drop to MVFR or even briefly IFR conditions will be likely. In addition, gusty winds and cloud to ground lightning will pose a threat. PREV DISCUSSION... /ISSUED 400 AM CDT THU AUG 15 2013/ SHORT TERM... Today and Tonight. Another chance of storms across the northwest Big Country this morning, and across much of the Big Country again late tonight. For the second night in a row, a complex of showers and storms is moving southeast towards the Big Country this morning. Much like earlier this morning, expect the activity to move southeast through sunrise and then quickly weaken and dissipate by mid morning. Will increase precipitation chances slightly across the area northwest of Abilene, but will wait and see how much progress the storms make before increasing them for the city itself. Other showers and storms have lingered across the Northwest Hill Country and the Northern Edwards Plateau early this morning. This activity is much more scattered and has weakened quicker than the storms farther north. At this point, will not boost pops in this southern area, and assume that they will weaken and dissipate even earlier, probably even before sunrise. Large upper level high pressure will continue across the southwest US, creating northwest and northerly flow through tonight. Models have some differences in the possibilities of more storms late tonight across the Big Country, with the NAM showing a potent shortwave generating another MCS moving south into the area late this evening and into the early morning hours. SPC is going along with this scenario and has placed a small portion of the Big Country into a Slight Risk for severe storms tonight. GFS is a little farther east with the storm complex, and slower as well, not bringing the rain into the area til near or after sunrise Friday morning. Confidence in the storm complex is fairly high, but given the uncertainty in the timing and track, will boost rain chances mainly across Haskell and Throckmorton counties for now. LONG TERM... Friday through next Wednesday. An MCS is expected to be diminishing across the northern part of the area Friday morning. How far south the complex will make it isn`t known...but it`s possible that it could be as far south as the Concho Valley and Heartland areas before finally dissipating. This argues for expanding the chance PoPs into the Concho Valley and Heartland areas for Friday, but mainly for morning activity. This complex would also likely leave an outflow boundary in the area for new thunderstorm development by Friday afternoon...so will keep the slight chance for showers and thunderstorms across the southern areas of the CWA for Friday as well. As flow aloft weakens through early next week, and the ridge expands back over the area, we continue to expect a dry forecast through next Tuesday with temperatures generally a few degrees above normal. By the middle of next week...both the GFS and EC show the easterly wave/trough currently in the western Caribbean moving into the Texas gulf coast and toward west central Texas. At this time, the main affect we will show is slightly cooler temperatures associated with lower heights from this feature for Wednesday. However...should the trough remain in tact into west central Texas, we may have another chance for showers and thunderstorms by Wednesday. && .PRELIMINARY POINT TEMPS/POPS... Abilene 92 71 95 69 92 / 30 20 30 20 5 San Angelo 94 71 97 70 94 / 20 20 20 20 5 Junction 95 72 98 71 95 / 30 20 20 10 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 24