Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/09/13
AREA FORECAST DISCUSSION
NWS TUCSON AZ
210 PM MST SAT SEP 7 2013
.SYNOPSIS...ABUNDANT MOISTURE WILL PRODUCE SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS THROUGH TUESDAY. A GRADUAL DECREASE IN
MOISTURE WILL THEN LEAD TO REDUCED SHOWER AND THUNDERSTORM ACTIVITY
DURING THE SECOND HALF OF THE UPCOMING WEEK.
&&
.DISCUSSION...PERSISTENT AREA OF SHOWERS CONTINUED ACROSS ERN
PIMA...SWRN GRAHAM...WRN COCHISE AND ERN SANTA CRUZ COUNTIES THIS
AFTERNOON. RADAR RAINFALL ESTIMATES AND GAUGE MEASUREMENTS RANGED
FROM JUST A FEW HUNDREDTHS OF AN INCH TO ABOUT 0.20 INCH DURING THE
PAST 3 HOURS. SEVERAL RUC HRRR SOLUTIONS MAINTAIN THIS AREA OF
SHOWERS DURING THE NEXT FEW HOURS FOLLOWED BY STRONGER PRECIP ECHOES
TO OCCUR THIS EVENING ACROSS GREENLEE/GRAHAM/COCHISE COUNTIES. HAVE
MAINTAINED SCATTERED SHOWERS AND ISOLATED TSTMS THRU TONIGHT.
SUN-MON...
OPTED TO INCREASE POPS GENERALLY 5-15 PERCENT THIS PERIOD. 07/12Z
GFS/ECMWF WERE SIMILAR WITH MOVING WEAK UPPER LOW OVER SRN SONORA
MIDDAY SUN NORTHWARD INTO FAR SE AZ BY MON AFTERNOON. NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS SHOULD PREVAIL...PARTICULARLY SUN
NIGHT-MON AS SYSTEM MOVES INTO THE AREA. PER COORD WITH WFO/S PSR/
FGZ...HAVE OPTED TO DEFER ANY FLASH FLOOD WATCH ISSUANCES TO
SUBSEQUENT SHIFTS. WIDESPREAD RAINFALL SHOULD OCCUR. HOWEVER...MUCH
UNCERTAINTY EXISTS AT THIS TIME REGARDING THE POTENTIAL FOR
WIDESPREAD FLASH FLOODING.
TUE-WED...
THE PROSPECT FOR SEVERE THUNDERSTORMS MAY INCREASE PARTICULARLY TUE
AFTERNOON/EVENING AS AXIS OF DEEPER MOISTURE SHIFTS EWD INTO WRN NEW
MEXICO. MEANWHILE...MID-LEVEL DRYING IS PROGGED TO MOVE INTO WRN
SECTIONS IN RESPONSE TO SWLY FLOW ALOFT AROUND WEAK LOW PRESSURE
CENTERED OVER THE GREAT BASIN. THE INTERFACE BETWEEN THE DEEPER
MOISTURE JUST EAST OF THE AREA AND THE SOMEWHAT DRIER AIR WEST MAY
LEAD TO STRONGER THUNDERSTORMS TUE AFTERNOON AND TUE EVENING...AND
PERHAPS NEAR THE NEW MEXICO BORDER WED AFTERNOON.
THUR-SAT...
EXPECT SOMEWHAT LESS COVERAGE OF SHOWERS/TSTMS AS DEEPER MOISTURE IS
PROGGED TO REMAIN JUST EAST OF THIS FORECAST AREA. HAVE OPTED FOR
SCATTERED AFTERNOON AND EVENING SHOWERS/TSTMS ACROSS ERN SECTIONS
WITH ISOLATED SHOWERS/TSTMS FROM TUCSON WWD/NWWD.
HIGH TEMPS SUN WILL BE SIMILAR TO TEMPS ACHIEVED THIS AFTERNOON.
COOLER MON FOLLOWED BY NO SIGNIFICANT CHANGE IN DAYTIME TEMPS TUE.
HIGH TEMPS MON-TUE ARE FORECAST TO AVERAGE ABOUT 10 DEGS F OR SO
BELOW NORMAL. A WARMING TREND IS ON TAP WED-FRI...WITH DAYTIME TEMPS
FRI-SAT TRENDING CLOSE TO SEASONAL NORMALS FOR MID-SEPTEMBER.
&&
.AVIATION...VALID THRU 00Z 09/09.
SCT-BKN MID LVL CLOUD DECK HAS LIMITED CONVECTIVE POTENTIAL TODAY
FOR BOTH KOLS/KTUS. HOWEVER...THERE REMAINS AMPLE MOISTURE IN PLACE
SO CONTINUED -SHRA/VCSH POSSIBLE. CU FIELD DEVELOPING E OF THE KDUG
TO KSAD LINE SO GIVEN MID LVL STEERING FLOW ISOLD TS POSSIBLE THRU
03Z ACROSS THIS AREA. OUTSIDE OF A BRIEF +SHRA EXPECT VFR CONDITIONS
AND LIGHT WINDS TO PREVAIL THRU THE PERIOD. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...EXPECT SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. STRONG...GUSTY AND ERRATIC WINDS WILL
OCCUR WITH THE STRONGER THUNDERSTORMS. THEREAFTER...DECREASED
MOISTURE WILL LEAD TO ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS DURING THE LATTER PART OF THE UPCOMING WEEK. BELOW
NORMAL DAYTIME TEMPERATURES WILL OCCUR THROUGH WEDNESDAY FOLLOWED BY
A WARMING TREND THURSDAY AND FRIDAY.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
DISCUSSION/FIRE WEATHER...FRANCIS
AVIATION...MEADOWS
AREA FORECAST DISCUSSION...UPDATED
NWS SAN JOAQUIN VALLEY - HANFORD CA
830 PM PDT SUN SEP 8 2013
.UPDATE...
UPDATED AIR QUALITY SECTION.
&&
.SYNOPSIS...
ISOLATED THUNDERSTORMS OVER THE SOUTHERN SIERRA NEVADA IN TULARE
AND KERN COUNTIES AND OVER THE EASTERN KERN DESERTS LATE THIS
AFTERNOON AND EVENING. OTHERWISE... DRY CONDITIONS WILL CONTINUE
OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH MONDAY WITH ABOVE
NORMAL TEMPERATURES. MONSOONAL MOISTURE...INCLUDING THE REMNANTS
OF TROPICAL DEPRESSION LORENA...IS EXPECTED TO RETURN TO THE
REGION BY TUESDAY FOR A SLIGHT CHANCE OF THUNDERSTORMS OVER THE
MOUNTAINS AND DESERT TUESDAY THROUGH THURSDAY.
&&
.UPDATED DISCUSSION...
THUNDERSTORMS SPREAD SOUTH INTO THE EASTERN KERN COUNTY DESERTS
EARLY THIS EVENING...AND CONTINUED OVER SOUTHERN INYO...NORTHWEST
SAN BERNARDINO AND EASTERN KERN COUNTY INTO THE LATE EVENING HOURS.
A FEW OF THESE STORMS HAVE PRODUCED STRONG RADAR RETURNS...AROUND 64
DBZ OR HIGHER...BUT AS OF 2030 PDT /0330Z MONDAY/ THERE HAVE BEEN NO
REPORTS OF HAIL OR HEAVY RAIN IN KERN COUNTY.
THE MODELS CONTINUE TO DIG THE UPPER-LEVEL TROUGH SOUTHWARD THROUGH
THE GREAT BASIN INTO SOUTHERN CALIFORNIA OVERNIGHT...CREATING A NORTH
FLOW ALOFT OVER THE HANFORD WARNING/FORECAST AREA. THIS FLOW IS
EVIDENT IN THE MOSTLY SOUTHERLY STORM MOTION OBSERVED THIS EVENING.
TEMPERATURES CONTINUED WELL ABOVE NORMAL TODAY...WITH N.A.S. LEMOORE
AND COALINGA THE HOT SPOTS IN THE REGION AT 104 DEGREES...WITH
FRESNO AND TAFT ONLY A DEGREE COOLER.
&&
.DISCUSSION...
THUNDERSTORMS HAVE DIMINISHED OVER THE TULARE COUNTY MOUNTAINS...
BUT ISOLATED STORMS CONTINUE OVER THE SOUTHERN SIERRA NEVADA IN
KERN COUNTY AND OVER THE EL PASO MOUNTAINS. ALSO...THUNDERSTORMS
HAVE DEVELOPED OVER SOUTHWESTERN INYO AND NORTHWESTERN SAN
BERNARDINO COUNTIES WHICH THE LATEST HRRR /HIGH-RESOLUTION RAPID
REFRESH/ RUNS SUGGEST MAY IMPACT THE INDIAN WELLS VALLEY THIS
EVENING.
HIGH TEMPERATURES AS OF 5 PM...
FRESNO........103
BAKERSFIELD...100
&&
.AVIATION...
AREAS OF MVFR CONDITIONS WITH ISOLATED IFR IN SMOKE OVER THE NORTH
SECTORS OF YOSEMITE AND MARIPOSA COUNTY. OTHERWISE...VFR CONDITIONS
WILL PREVAIL ACROSS THE CENTRAL CA INTERIOR DURING THE NEXT 24
HOURS.
&&
.PREV DISC... /ISSUED 327 PM PDT SUN SEP 8 2013/
DISCUSSION...CONVECTION OVER THE SOUTHERN SIERRA HAS RESULTED IN
A FEW THUNDERSTORMS ACROSS SOUTHEASTERN TULARE COUNTY THIS AFTERNOON.
SO FAR CELLS ARE FAIRLY BENIGN BUT DUE TO THEIR SLOW MOVEMENT TO THE
SOUTH TOWARDS THE NORTHEAST KERN COUNTY DESERT...WILL NEED TO BE
WATCHED FOR THE POTENTIAL OF LOCALLY HEAVY RAINFALL. MONSOON MOISTURE
IS BEING WRAPPED AROUND A MID LEVEL LOW CIRCULATION CENTERED AROUND
THE CALIFORNIA...NEVADA AND ARIZONA TRIPLE POINT. 12Z KVEF SOUNDING
MEASURED 1.59" PRECIPITABLE WATER. BLENDED TPW IMAGERY SHOWS AROUND
1 INCH ACROSS SE TULARE AND KERN COUNTIES WITH THE HIGHEST MOISTURE
CENTERED OVER THE LOWER COLORADO RIVER BASIN...UPWARDS OF 1.75".
AFTERNOON HEATING AND WEAK VORTICITY ADVECTION WILL CONTINUE THE
THREAT OF THUNDERSTORMS ALONG THE SOUTHERN SIERRA CREST FROM FRESNO
COUNTY SOUTH WITH ACTIVITY SLOWLY SHIFTING SOUTHWARD OVER EASTERN
KERN COUNTY. EXPECTING THESE STORMS TO GRADUALLY DIMINISH THROUGH
THE EVENING BUT VORT ENERGY COULD KEEP THINGS GOING A BIT LONGER.
LATEST NAM KEEPS THE LOW CENTER NEARLY STATIONARY THROUGH TUESDAY
WITH THE WESTERN FRINGE OF MOISTURE EXTENDING TO THE SOUTHERN SIERRA.
RIGHT NOW IT LOOKS A LITTLE LESS FAVORABLE FOR CONVECTION ON MONDAY
WITH THE LACK OF A NOTABLE VORT BUT DAYTIME HEATING ALONE MAY BE
SUFFICIENT. SLIGHT CHANCE POPS REMAIN ALONG THE SO SIERRA CREST AND
DOWN INTO THE KERN COUNTY DESERT TUES-WED...THEN JUST ALONG THE CREST
OF THE SIERRA ON THURSDAY AS MOISTURE IS NUDGED EASTWARD.
OTHERWISE...THE LARGE UPPER HIGH REMAINS OVER THE PLAINS STATES WITH
THE PAC NW UPPER LOW BEGINNING TO OPEN UP AS IT SHIFTS EASTWARD OVER
WESTERN MONTANA. TEMPERATURES WILL CONTINUE TO RUN SEVERAL DEGREES
ABOVE CLIMO THROUGH TUESDAY...THEN SLIGHTLY COOLER AIR IS EXPECTED
ON WEDNESDAY. KEPT TEMPS FAIRLY STEADY FOR THE END OF THE WEEK AND
NEXT WEEKEND WITH HIGHS SLIGHTLY ABOVE NORMAL.
&&
.AIR QUALITY ISSUES...
ON MONDAY SEPTEMBER 9 2013...UNHEALTHY FOR SENSITIVE GROUPS IN
FRESNO...KERN...KINGS...MADERA...MERCED AND TULARE COUNTIES.
FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG
TUOLUMNE COUNTY...SEE SFOAQAHNX.
FOR ADDITIONAL INFORMATION...CALL YOUR LOCAL AIR DISTRICT
TUOLUMNE COUNTY AIR DISTRICT OFFICE...209.533.5693
&&
.CERTAINTY...
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS HIGH.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS MEDIUM.
THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.
&&
.CLIMATE...
RECORDS
SITE DATE HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR
KFAT 09-08 108:1904 76:1931 74:1998 49:1897
KFAT 09-09 107:1904 75:1985 76:1888 50:1964
KFAT 09-10 108:1888 68:1952 76:1888 48:1952
KBFL 09-08 109:1904 77:1914 78:1977 47:1915
KBFL 09-09 108:1904 76:1985 80:1982 48:1901
KBFL 09-10 107:1944 74:1952 75:1984 49:1920
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...SANGER
AVN/FW...DS
PREV DISCUSSION...DCH
SYNOPSIS...WP
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
500 PM PDT SUN SEP 8 2013
.UPDATE...
UPDATED AIR QUALITY SECTION.
&&
.SYNOPSIS...
ISOLATED THUNDERSTORMS OVER THE SOUTHERN SIERRA NEVADA IN TULARE
AND KERN COUNTIES AND OVER THE EASTERN KERN DESERTS LATE THIS
AFTERNOON AND EVENING. OTHERWISE... DRY CONDITIONS WILL CONTINUE
OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH MONDAY WITH ABOVE
NORMAL TEMPERATURES. MONSOONAL MOISTURE...INCLUDING THE REMNANTS
OF TROPICAL DEPRESSION LORENA...IS EXPECTED TO RETURN TO THE
REGION BY TUESDAY FOR A SLIGHT CHANCE OF THUNDERSTORMS OVER THE
MOUNTAINS AND DESERT TUESDAY THROUGH THURSDAY.
HIGH TEMPERATURES AS OF 5 PM...
FRESNO........103
BAKERSFIELD...100
&&
.DISCUSSION...
THUNDERSTORMS HAVE DIMINISHED OVER THE TULARE COUNTY MOUNTAINS...
BUT ISOLATED STORMS CONTINUE OVER THE SOUTHERN SIERRA NEVADA IN
KERN COUNTY AND OVER THE EL PASO MOUNTAINS. ALSO...THUNDERSTORMS
HAVE DEVELOPED OVER SOUTHWESTERN INYO AND NORTHWESTERN SAN
BERNARDINO COUNTIES WHICH THE LATEST HRRR /HIGH-RESOLUTION RAPID
REFRESH/ RUNS SUGGEST MAY IMPACT THE INDIAN WELLS VALLEY THIS
EVENING.
&&
.AVIATION...
AREAS OF MVFR CONDITIONS WITH ISOLATED IFR IN SMOKE OVER THE NORTH
SECTORS OF YOSEMITE AND MARIPOSA COUNTY. OTHERWISE...VFR CONDITIONS
WILL PREVAIL ACROSS THE CENTRAL CA INTERIOR DURING THE NEXT 24
HOURS.
&&
.PREV DISC... /ISSUED 327 PM PDT SUN SEP 8 2013/
DISCUSSION...CONVECTION OVER THE SOUTHERN SIERRA HAS RESULTED IN
A FEW THUNDERSTORMS ACROSS SOUTHEASTERN TULARE COUNTY THIS AFTERNOON.
SO FAR CELLS ARE FAIRLY BENIGN BUT DUE TO THEIR SLOW MOVEMENT TO THE
SOUTH TOWARDS THE NORTHEAST KERN COUNTY DESERT...WILL NEED TO BE
WATCHED FOR THE POTENTIAL OF LOCALLY HEAVY RAINFALL. MONSOON MOISTURE
IS BEING WRAPPED AROUND A MID LEVEL LOW CIRCULATION CENTERED AROUND
THE CALIFORNIA...NEVADA AND ARIZONA TRIPLE POINT. 12Z KVEF SOUNDING
MEASURED 1.59" PRECIPITABLE WATER. BLENDED TPW IMAGERY SHOWS AROUND
1 INCH ACROSS SE TULARE AND KERN COUNTIES WITH THE HIGHEST MOISTURE
CENTERED OVER THE LOWER COLORADO RIVER BASIN...UPWARDS OF 1.75".
AFTERNOON HEATING AND WEAK VORTICITY ADVECTION WILL CONTINUE THE
THREAT OF THUNDERSTORMS ALONG THE SOUTHERN SIERRA CREST FROM FRESNO
COUNTY SOUTH WITH ACTIVITY SLOWLY SHIFTING SOUTHWARD OVER EASTERN
KERN COUNTY. EXPECTING THESE STORMS TO GRADUALLY DIMINISH THROUGH
THE EVENING BUT VORT ENERGY COULD KEEP THINGS GOING A BIT LONGER.
LATEST NAM KEEPS THE LOW CENTER NEARLY STATIONARY THROUGH TUESDAY
WITH THE WESTERN FRINGE OF MOISTURE EXTENDING TO THE SOUTHERN SIERRA.
RIGHT NOW IT LOOKS A LITTLE LESS FAVORABLE FOR CONVECTION ON MONDAY
WITH THE LACK OF A NOTABLE VORT BUT DAYTIME HEATING ALONE MAY BE
SUFFICIENT. SLIGHT CHANCE POPS REMAIN ALONG THE SO SIERRA CREST AND
DOWN INTO THE KERN COUNTY DESERT TUES-WED...THEN JUST ALONG THE CREST
OF THE SIERRA ON THURSDAY AS MOISTURE IS NUDGED EASTWARD.
OTHERWISE...THE LARGE UPPER HIGH REMAINS OVER THE PLAINS STATES WITH
THE PAC NW UPPER LOW BEGINNING TO OPEN UP AS IT SHIFTS EASTWARD OVER
WESTERN MONTANA. TEMPERATURES WILL CONTINUE TO RUN SEVERAL DEGREES
ABOVE CLIMO THROUGH TUESDAY...THEN SLIGHTLY COOLER AIR IS EXPECTED
ON WEDNESDAY. KEPT TEMPS FAIRLY STEADY FOR THE END OF THE WEEK AND
NEXT WEEKEND WITH HIGHS SLIGHTLY ABOVE NORMAL.
&&
.AIR QUALITY ISSUES...
ON MONDAY SEPTEMBER 9 2013...UNHEALTHY FOR SENSITIVE GROUPS IN
FRESNO...KERN...KINGS...MADERA...MERCED AND TULARE COUNTIES.
FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG
TUOLUMNE COUNTY...SEE SFOAQAHNX.
FOR ADDITIONAL INFORMATION...CALL YOUR LOCAL AIR DISTRICT
TUOLUMNE COUNTY AIR DISTRICT OFFICE...209.533.5693
&&
.CERTAINTY...
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS HIGH.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS MEDIUM.
THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.
&&
.CLIMATE...
RECORDS
SITE DATE HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR
KFAT 09-08 108:1904 76:1931 74:1998 49:1897
KFAT 09-09 107:1904 75:1985 76:1888 50:1964
KFAT 09-10 108:1888 68:1952 76:1888 48:1952
KBFL 09-08 109:1904 77:1914 78:1977 47:1915
KBFL 09-09 108:1904 76:1985 80:1982 48:1901
KBFL 09-10 107:1944 74:1952 75:1984 49:1920
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...SANGER
AVN/FW...DS
PREV DISCUSSION...DCH
SYNOPSIS...WP
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
115 PM PDT SAT SEP 7 2013
.SYNOPSIS...
SCATTERED THUNDERSTORMS WILL DIMINISH THIS EVENING OVER THE
MOUNTAINS...BUT MAY REFIRE AGAIN ON SUNDAY AFTERNOON WITH LINGERING
MONSOONAL MOISTURE. LOW PRESSURE WILL BE DEVELOPING ALONG THE WEST
COAST EARLY NEXT WEEK...BRINGING COOLER WEATHER AND DECREASING
THUNDERSTORM CHANCES OVER THE MOUNTAINS AND DESERTS.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHOWERS AND TSTMS GOT AN EARLY START LATE THIS MORNING OVER THE
MOUNTAINS...AND EXPECT IT WILL BE ANOTHER VERY ACTIVE AFTERNOON AND
EVENING. GPS SOUNDERS OVER THE DESERTS ARE ESTIMATING PW VALUES
AROUND TWO INCHES SO PLENTY OF FUEL FOR TORRENTIAL RAINFALL AGAIN
UNTIL AROUND SUNSET. A FEW TSTMS MAY POP OVER THE INLAND EMPIRE AS
WELL...BUT WATER VAPOR IMAGERY AND SOUNDERS WEST OF THE MOUNTAINS
SHOW THE MOIST LAYER IS SHALLOW. QUITE WARM TO HOT AGAIN THIS
AFTERNOON WITH TEMPS IN THE 80S NEAR THE COAST...AND 90S TO AROUND
100 F INLAND. VERY WEAK SFC PRESSURE GRADIENTS AT MIDDAY.
DUE TO THE VERY HIGH DEWPOINTS OVER THE LOWER DESERTS...THE
OPERATIONAL EMC RAP INDICATES SURFACE-BASED CAPES APPROACHING 3500
OVER THE LOWER DESERTS THIS AFTERNOON. SHOULD THIS AREA CONVECT...
THUNDERSTORMS COULD APPROACH SEVERE LIMITS AS WELL AS PRODUCE
TORRENTIAL DOWNPOURS. THE 18Z 3-KM HRRR HAS MODELED THE BEGINNING OF
THE CONVECTION WELL TODAY AND DOES NOT INDICATE ANY ACTIVITY IN THE
COACHELLA VALLEY THIS AFTERNOON. HOWEVER CONVECTION DOES BECOME
INTENSE OVER THE SANTA ROSAS...AND OVER THE SAN DIEGO COUNTY
DESERTS. NUMEROUS HRRR RUNS ALSO SHOW ISOLATED CONVECTION OVER THE
INLAND EMPIRE. ANY STORMS THAT DEVELOP OVER THE IE WILL WILL NOT
HAVE THE DEEP LAYER MOISTURE AVAILABLE OVER THE MTNS/DESERTS.
GLOBAL MODELS GENERALLY AGREE THE LARGE SUBTROPICAL HIGH...CENTERED
OVER THE GREAT PLAINS...WILL DRIFT EASTWARD THROUGH TUE...WHILE A
WEAK TROUGH DEVELOPS SOUTHWARD OVER SOCAL. THIS WILL ALLOW HEIGHTS/
THICKNESS TO DROP OFF ACROSS THE REGION...AND GRADUALLY ALLOW THE
MARINE LAYER TO BECOME REESTABLISHED NEXT WEEK. IN THE MEANTIME...
THE SLOW EASTWARD PROPAGATION OF THE TROUGH AXIS THROUGH THE REGION
SHOULD SHUNT THE DEEP LAYER MONSOONAL MOISTURE OFF TO THE EAST...
DECREASING THE TSTM CHANCES OVER THE MTNS/DESERTS NEXT WEEK.
REMNANTS OF TROPICAL STORM LORENA ARE DRAWN NORTHWARD AHEAD OF THE
TROUGH EARLY NEXT WEEK SO PLACEMENT OF THE DEVELOPING TROUGH AXIS IS
CRITICAL. BOTH THE 12Z ECMWF/GFS SHOW THE TROUGH AXIS E OF THE CWA
ON MON. THIS SHOULD KEEP THE BULK OF THE CLOUDS AND MOISTURE TO OUR
EAST AND THE 12Z ECMWF SEEMS TO BE TRENDING CLOSER THE THE GFS
SOLUTION. THE NAM 12 STILL SHOWS THE MTNS EAST CONVECTING ON
MON...BUT NO NOCTURNAL ACTIVITY OVER THE AREA. POPS HAVE BEEN PARED
BACK EARLY NEXT WEEK...EXPECTING THE BIGGER THREAT MORE TO THE EAST.
LOOKING AHEAD TO THE END OF NEXT WEEK...12Z GLOBAL MODEL RUNS STILL
DIVERGE OVER THE SW. BOTH THE GFS/ECMWF LOOK DRY...BUT THE GFS IS
FAVORED AND A BIT WARMER.
&&
.AVIATION...
072010Z...COAST/VALLEYS...FROM 2100 UTC THROUGH 08/0300
UTC...THUNDERSTORMS OVER MTNS WILL PRODUCE SCT-FEW DEBRIS CLDS AOA
8000 FT MSL OVER THE COAST/VALLEYS. SLIGHT CHANCE OF FOG REACHING
KSAN...KCRQ...AND/OR KSNA DURING THE 08/1100-1500 UTC
TIME-FRAME...BUT CONFIDENCE IS LOW IN THIS OCCURRING.
OTHERWISE...UNRESTRICTED VIS AND MOSTLY SKC THROUGH SUNDAY MORNING.
MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS THROUGH 08/0100
UTC WITH BASES 7000-10000 FT MSL AND CB TOPS TO 40000 FT
MSL...RESULTING IN LOCAL VIS AOB 2SM IN HEAVY RAIN...SMALL
HAIL...AND POSSIBLE STRONG UP/DOWNDRAFTS. OTHERWISE...UNRESTRICTED
VIS THROUGH SUNDAY MORNING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH FROM 11 AM PDT TODAY THROUGH THIS EVENING FOR
THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE
COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO
COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.
PZ...NONE.
&&
$$
PUBLIC...JAD
AVIATION...HARRISON
AREA FORECAST DISCUSSION...RETRANSMISSION
NWS SAN DIEGO CA
845 AM PDT SAT SEP 7 2013
.SYNOPSIS...
CONTINUED VERY WARM AND HUMID TODAY WITH SCATTERED AFTERNOON
THUNDERSTORMS AGAIN OVER THE MOUNTAINS. THE THUNDERSTORMS WILL
LIKELY PRODUCE TORRENTIAL DOWNPOURS WITH LOCAL FLASH FLOODING
POSSIBLE. LOW PRESSURE WILL BE DEVELOPING ALONG THE WEST COAST EARLY
NEXT WEEK...BRINGING COOLER WEATHER AND DECREASING THUNDERSTORM
CHANCES OVER THE MOUNTAINS AND DESERTS.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SKIES WERE MOSTLY CLEAR EARLY THIS MORNING OVER THE CWA.
HOWEVER...WATER VAPOR IMAGERY INDICATED A SHARP MOISTURE BOUNDARY IN
THE ATMOSPHERE ALONG THE FOOTHILLS. THE 12Z MIRAMAR SOUNDING HAD A
SFC BASED INVERSION WITH LIGHT WINDS UP THROUGH 25K FT. PW HAD
DECREASED TO 1.43 INCHES...BUT GPS SOUNDERS AND SFC DEWPOINT
INCREASES ACROSS THE DESERTS SUPPORT PWS CLOSER TO TWO INCHES. SFC
PRESSURE GRADIENTS AT 14Z ARE WEAK OFFSHORE.
CONTINUED VERY WARM TO HOT AND HUMID AGAIN TODAY. MAIN CONCERN AGAIN
WILL BE THE THUNDERSTORM AND FLASH FLOOD THREAT OVER THE MTNS/
DESERTS. HIGH PW VALUES OVER EASTERN PORTIONS OF THE AREA SUPPORT A
FLASH FLOOD WATCH THIS AFTERNOON AND EVENING. THE 12Z MIRAMAR
SOUNDING LOOKS A BIT MORE STABLE...BUT IT IS IN A DIFFERENT AIRMASS
THAN THE DESERTS. THE LOCAL WRF/HRRR/NAM12 ALL DEVELOP THUNDERSTORMS
OVER THE MTNS THIS AFTERNOON. THE 12Z HRRR ALSO SHOWS ISOLATED
CONVECTION OVER THE INLAND EMPIRE WHICH IS SUPPORTED BY HIGHER SFC
DEWPOINTS AND EASTERLY FLOW THROUGH THE BANNING PASS THIS MORNING.
ANY STORMS THAT DEVELOP OVER THE IE WILL WILL NOT HAVE THE DEEP
LAYER MOISTURE AVAILABLE OVER THE MTNS/DESERTS...SO IT IS NOT
INCLUDED IN THE FLASH FLOOD WATCH.
GLOBAL MODELS GENERALLY AGREE THE LARGE SUBTROPICAL HIGH...CENTERED
OVER THE GREAT PLAINS...WILL DRIFT EASTWARD THROUGH TUE...WHILE A
WEAK TROUGH DEVELOPS SOUTHWARD OVER SOCAL. THIS WILL ALLOW HEIGHTS/
THICKNESS TO DROP OFF ACROSS THE REGION...AND GRADUALLY ALLOW THE
MARINE LAYER TO BECOME REESTABLISHED NEXT WEEK. IN THE MEANTIME...
THE SLOW EASTWARD PROPAGATION OF THE TROUGH AXIS THROUGH THE REGION
SHOULD SHUNT THE DEEP LAYER MONSOONAL MOISTURE OFF TO THE EAST...
DECREASING THE TSTM CHANCES OVER THE MTNS/DESERTS NEXT WEEK.
REMNANTS OF TROPICAL STORM LORENA ARE DRAWN NORTHWARD AHEAD OF THE
TROUGH EARLY NEXT WEEK SO PLACEMENT OF THE DEVELOPING TROUGH AXIS IS
CRITICAL. BOTH THE 00Z ECMWF/06Z GFS SHOW THE AXIS E OF THE CWA ON
MON. THIS SHOULD KEEP THE BULK OF THE CLOUDS AND MOISTURE TO OUR
EAST...HOWEVER THE 00Z ECMWF RUN PULLS IT BACK INTO THE UPPER LOW
CIRCULATION WHICH RESULTS IN CONTINUED PRECIP CHANCES FOR THE ENTIRE
CWA INTO MON. FOR NOW...FAVOR THE GFS MOISTURE FIELD/PCPN...KEEPING
THE THREAT MORE TO THE EAST.
LOOKING AHEAD TO THE END OF NEXT WEEK...00Z/06Z GLOBAL MODEL RUNS
DIVERGE OVER THE SW. BOTH THE GFS/ECMWF LOOK DRY...BUT THE GFS IS
WARMER.
&&
.AVIATION...
071508Z...COAST/VALLEYS...DURING THE 1900-08/0300 UTC
TIME-PERIOD...THUNDERSTORMS OVER MTNS WILL PRODUCE SCT-FEW DEBRIS
CLDS AOA 8000 FT MSL OVER THE COAST/VALLEYS. SLIGHT CHANCE OF FOG
REACHING KSAN...KCRQ...AND/OR KSNA DURING THE 08/1100-1500 UTC
TIME-FRAME...BUT CONFIDENCE IS LOW IN THIS OCCURRING.
OTHERWISE...UNRESTRICTED VIS AND MOSTLY SKC THROUGH SUNDAY MORNING.
MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS DURING THE
1800-08/0100 UTC TIME-PERIOD WITH BASES 7000-10000 FT MSL AND CB
TOPS TO 40000 FT MSL...RESULTING IN LOCAL VIS AOB 2SM IN HEAVY
RAIN...SMALL HAIL...AND POSSIBLE STRONG UP/DOWNDRAFTS.
OTHERWISE...UNRESTRICTED VIS THROUGH SUNDAY MORNING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH FROM 11 AM PDT TODAY THROUGH THIS EVENING FOR
THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE
COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO
COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.
PZ...NONE.
&&
$$
PUBLIC...JAD
AVIATION...HARRISON
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
638 PM MDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 637 PM MDT SUN SEP 8 2013
THE FEATURE TO WATCH FOR THE NEXT 6-12 HOURS IS THE VORT CENTER
STREAMING NORTHWARD OVER NE ARIZONA. AS THIS VORT CENTER MOVES
INTO ERN UTAH LATER TONIGHT...DEFORMATION AXIS BETWEEN DEEP
SUBTROPICAL PLUME ATTACHES ITSELF WITH THE NRN STREAM MONTANA
SHORT WAVE. IN THE RAP MODEL...QPF AMOUNTS ACROSS EAST CENTRAL
UTAH INTO NORTHWEST COLORADO IS SIGNIFICANT WITH SOME AREAS
EXCEEDING AN INCH. THE MOST NOTABLE IS OVER THE TAVAPUTS WITH OVER
3 INCHES OF RAIN. FORECASTING QPF IS TRICKY AND NOT SURE HOW MUCH
IS ATTRIBUTED TO CONVECTIVE PROCESSES WITH THE MODEL. PRUDENT TO
WATCH OBSERVATIONAL TRENDS THIS EVENING.
&&
.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 351 PM MDT SUN SEP 8 2013
H5 HAND ANALYSIS CENTERED THE SUB-TROPICAL RIDGE OVER THE EASTERN
PLAINS OF KANSAS. UPSTREAM A STRONGER LOW PRESSURE CIRCULATION WAS
CENTERED NEAR THE PANHANDLE OF IDAHO. THE BEST HEIGHT FALLS REMAIN
EAST OF THE LOW AND THE MODEL FORECASTS OF TRACKING THIS FEATURE
ALONG THE US/CANADIAN BORDER OVER THE NEXT 24 TO 48 HOURS LOOKS ON
TRACK. A MORE DIFFUSE...BUT IMPORTANT CIRCULATION CAN ALSO BE SEEN
SPINNING NEAR THE SOCAL/AZ BORDER. THE GRADIENT BETWEEN THE
WESTERN TROUGHS AND EASTERN RIDGE IS PROVIDING A PERSISTENT FETCH
OF DEEP MONSOONAL MOISTURE INTO WESTERN COLORADO AND EASTERN UTAH.
GOES DERIVED IMAGERY SHOWS AN IMPRESSIVE RING OF PWAT EXTENDING
FROM THE HIGH COUNTRY OF MEXICO INTO THE GREAT BASIN...NORTHERN
PLAINS AND BACK INTO THE MO RIVER VALLEY. PWATS ARE GENERALLY 175
- 200 PERCENT OF NORMAL IN THIS RING INCLUDING KGJT.
DYNAMICS...THERMAL INSTABILITY AND THIS MOISTURE BE PRESENT FOR
THE FIRST PART OF THE WEEK OVER OUR CWA WHICH WILL LEAD TO A WET
FORECAST FOR MANY AREAS. TEMPERATURES WILL BE LIMITED BY THE
PRECIPITATION AND CLOUDS AND WILL END UP BELOW NORMAL TO START OUT
THE WEEK.
THE CONVECTION IN OUR CWA IS MOST PROLIFIC NEAR THE THICKER CLOUD
INTERFACE FROM EARLIER TODAY. THESE STORMS ARE MOVING NORTHWARD
AROUND 25 MPH AND SO FAR THE THREAT OF FLOODING OUTSIDE THE WATCH IS
MINIMAL. MORE ORGANIZED CONVECTION IS LOCATED OVER SOUTH CENTRAL UTAH
AND NORTHERN ARIZONA. THIS IS ASSOCIATED WITH ENERGY FROM THE
SOUTHERN LOW AND AN UPPER JET MAXIMA EXTENDING NORTHEAST INTO
WESTERN WYOMING AHEAD OF THE APPROACHING NORTHERN TROF. THIS AREA OF
ENHANCED ASCENT WILL BE SHIFTING EASTWARD THIS EVENING AND
OVERNIGHT. THE MOISTURE PLUME WILL BE SQUEEZED INTO OUR CWA WITH
PWATS LOOKING TO SPIKE AT 1.2-1.4 INCHES NEAR THE UTAH/CO BORDER.
LIFT ASSOCIATED WITH A DEFORMATION/SHEAR AXIS BETWEEN THE TROF AND
THE RIGHT ENTRANCE REGION OF THE UPPER JET ALL LOOK TO BRING
DECENT PRECIPITATION CHANCES TO EASTERN UTAH AND NORTHWEST
COLORADO THROUGH SUNRISE. ISOLATED THUNDERSTORMS WILL BE EMBEDDED
IN THE PRECIPITATION PROVIDING AN HEAVY RAIN THREAT. HOWEVER WITH
A DEEP WARM CLOUD LAYER EVEN THE SHALLOW CONVECTION SHOULD BE
EFFICIENT AT MAKING RAIN.
CONFIDENCE NOT QUITE HIGH ENOUGH TO EXPAND WATCH EAST OR NORTHWARD
INTO TOMORROW. THE PLUME LOOKS TO BE CENTERED FROM THE FOUR CORNERS
TO THE NORTHERN MOUNTAINS BY TOMORROW AFTERNOON...THE NORTHERN END
ARCING WESTWARD BY THE PULL OF THE NORTHERN STREAM TROF MOVING INTO
THE WESTERN DAKOTAS. THIS PLUME LEAVES A THICK CLOUD LAYER OVER MUCH
OF THE CWA...AND SHOULD HELP LIMIT DEEP CONVECTION THROUGH EARLY
AFTERNOON. DRIER AIR LOOKS TO FILTER INTO THE FAR NORTHWEST CWA
BEHIND THE TROF AND MODELS INSIST ON LIMITING THE CONVECTION HERE.
WHILE IN THE 4 CORNERS REGION...ASCENT REMAINS STRONG IN THE
MOISTURE PLUME AS MODELS SHOW ENERGY ARRIVING BY PEAK HEATING TO
HELP BLOSSOM THE CONVECTION. AGAIN EXPECT ANOTHER ROUND OF LATE
NIGHT PRECIPITATION TO LINGER INTO TUESDAY MORNING FAVORED FROM
SOUTHEAST UTAH INTO THE CENTRAL MOUNTAINS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 351 PM MDT SUN SEP 8 2013
THE SUBTROPICAL MOISTURE PLUME WILL CONTINUE TO STREAM DIRECTLY
OVER THE FORECAST AREA AS THE PATTERN BECOMES BLOCKED OVER THE
WESTERN CONUS. THE FIRST SHORTWAVE WILL HAVE MOVED INTO THE
NORTHERN PLAINS BY TUE MORNING...WITH A HIGH PRESSURE RIDGE
REPLACING IT OVER THE PACIFIC NORTHWEST. AS THE NORTHERN BRANCH
SHORTWAVE CONTINUES EAST ON TUE...LOW PRESSURE WILL LINGER OVER
THE DESERT SOUTHWEST AND GREAT BASIN. THE NORTHWEST HIGH AND
SOUTHWEST LOW WILL FORM A REX BLOCK OF SORTS THAT WILL GRADUALLY
EVOLVE BY THE END OF THE WEEK. THE HIGH IS PROGGED TO WEAKEN AND
SHIFT EAST...FORMING A STRONG RIDGE TO OUR EAST...STILL KEEPING A
BLOCK-ISH PATTERN. THE GFS IS QUICKEST IN MOVING OUT THE SOUTHWEST
LOW LATE IN THE WORK WEEK. HOWEVER NATIONAL DISCUSSIONS PREFER A
SLOWER SOLUTION. WITH A SOUTHWEST LOW IN PLACE FOR MOST OF THE
LATE SUMMER...I PREFER THE SLOWER SOLUTION AS WELL. THEREFORE WILL
GENERALLY FOLLOW THE ECMWF FOR THIS FORECAST.
THAT SAID...MADE FEW CHANGES TO THE FORECAST. THE LARGER SCALE
PATTERN AS DESCRIBED ABOVE KEEPS THE THE MOISTURE PLUME PRETTY
MUCH OVERHEAD. THERE ARE SOME NUANCES THOUGH THAT MAY DETERMINE
JUST HOW WET WE WILL REMAIN. ON TUE/TUE NIGHT...THE UPPER LOW
CENTER IS PROGGED TO MOVE NORTHWARD FROM SOUTHWEST AZ TO THE
AZ/NV/UT TRIPLE POINT. AT THE LOWER LEVELS...THE RESULTING
EASTERLY FLOW OVER OUR FORECAST AREA CAN HAVE A SUPPRESSING
INFLUENCE ON PRECIPITATION. HOWEVER DEEP MOISTURE WILL CONTINUE TO
BE IN PLACE. AND WITH THE LOW JUST TO OUR WEST...WE SHOULD SEE
SOME ENHANCED INSTABILITY DUE TO ITS PROXIMITY. THEN ACCORDING TO
THE EC...THE LOW STALLS OVER SOUTHWEST UT THROUGH THE END OF THE
WEEK. MODELS INDICATE THAT A WAVE WILL ROTATE OFF THE LOW AND
SWEEP OVER OUR NORTHWEST CORNER ON WED OR THU. CONFIDENCE IN THE
DETAILS IS LACKING ON THIS FEATURE...BUT STILL KEPT POPS
RELATIVELY HIGH. A SLIGHT DRYING IS PROGGED BY LATE IN THE
WEEK...AND BY EARLY NEXT WEEK EVEN THE EC MOVES THE LOW TO THE
NORTHEAST.
TEMPERATURES WILL REMAIN ON THE COOL SIDE...ESPECIALLY COMPARED
TO THE VERY WARM CONDITIONS WE HAVE SEEN RECENTLY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 351 PM MDT SUN SEP 8 2013
VFR CONDITIONS WILL GENERALLY PREVAIL ACROSS ALL OF THE FORECAST
TERMINALS THIS EVENING INTO MONDAY. SHOWERS AND THUNDERSTORMS
CONTINUE TO EXPAND LATE THIS AFTERNOON AND THIS COULD LEAD TO
FLIGHT CONDITIONS BEING TEMPORARILY IMPACTED. THE MAIN THREATS
WILL BE BRIEF HEAVY RAINFALL AND GUSTY WINDS AND AN OUTSIDE CHANCE
THAT LOWERED FLIGHT CRITERIA WILL PASS THROUGH. IN ELEVATIONS
ABOVE 9500 FEET...MOUNTAIN OBSCURATIONS WILL BE MORE LIKELY
INTO THE OVERNIGHT HOURS AND A FEW STORMS MAY BE ABLE TO DROP SOME
SMALL HAIL. UNSETTLED CONDITIONS WILL CONTINUE INTO MONDAY AS A
STRONG PLUME OF MOISTURE SETTLES OVER WESTERN COLORADO AND EASTERN
UTAH.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR COZ020-021.
UT...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR UTZ022-025-027>029.
&&
$$
UPDATE...PF
SHORT TERM...15
LONG TERM...EH
AVIATION...TGJT
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
145 PM MDT SUN SEP 8 2013
.AVIATION...LOOKS LIKE A FEW STORMS MAY FIRE OFF OF THE BOUNDARY
OVER THE PALMER DIVIDE...AS THE HIGH RES MODELS HAVE BEEN POINTING
TO. AND...THE BOUNDARY DOESNT SEEM TO BE MOVING WEST MUCH TO BRING
THE SOUTH-SOUTHEASTERLY WINDS TO THE AIRPORTS. THEREFORE...WILL
TAKE OUT THE SOUTHEAST WINDS OUT KEEPING THE LIGHT NORTHERLY
WINDS. WILL MAKE EXPECTED WINDS FROM OUTFLOW BE GENERALLY FROM THE
SOUTHWEST INSTEAD OF THE EARLIER FORECAST OF NORTHWEST. AFTER
CONVECTIVE BOUNDARIES MOVE ACROSS WINDS SHOULD GRADUALLY SHIFT
BACK TO MORE SSW BY 06Z. OVERNIGHT LOOKS LIKE A A SHIFT TO NLY
WINDS WILL OCCUR IN THE 12Z-15Z TIMEFRAME ON MON AS A COOL FRONT
MOVE ACROSS. AT THIS TIME NO LOW CLOUDS ARE EXPECTED WITH THIS
FEATURE. WILL SEE MORE CONVECTIVE ACTIVITY MONDAY AROUND THE
AIRPORTS.
&&
.PREV DISCUSSION... /ISSUED 1107 AM MDT SUN SEP 8 2013/
UPDATE...STRONG SOUTHERLY WINDS ARE SURFACING OVER THE FAR
EASTERN PLAINS WITH GUSTS TO 35 MPH. HUMIDITIES ARE IN THE UPPER
TEENS TO LOWER 20 PERCENT RANGE AND ARE NOT EXPECTED TO DROP MUCH
MORE. THERE MAY BE A FEW SPOTTY AREAS THAT HIT WARNING
CRITERIA...BUT NOT FOR LONG.
BUILDING CUMULUS OVER THE HIGH TERRAIN WILL CONTINUE WITH
SCATTERED STORMS THIS AFTERNOON. EXPECTING SLIGHTLY MORE MOISTURE
BUT STORMS WILL BE MOVING QUICKER TODAY.
ONLY MADE MINOR ADJUSTMENTS TO TEMPERATURES AND WINDS IN THE
GRIDS FOR THE MORNING UPDATE.
AVIATION...WINDS ARE BECOMING TRICKY FOR THE AREA AIRPORTS.
NORTHERLY WINDS ARE STICKING AROUND LONGER WITH THE EDGE OF
SOUTHERLY WINDS BEGINNING TO SHOW UP ON RADAR OVER FAR EASTERN
ADAMS AND ARAPAHOE COUNTIES. KEEP PUSHING OFF THE SOUTHEAST WINDS
UNTIL LATER. LAST FEW RUNS OF THE RAP SHOWS A RATHER STG OUTFLOW
BNDRY COMING OUT OF THE FOOTHILLS AND ACROSS DIA IN THE 22Z-00Z
TIME PERIOD ALONG WITH SOME ISOLD HIGHER BASED STORMS SO BACK UP
THE TIMING OF THE TEMPO GROUP FOR GUSTY OUTFLOW WINDS FOR A FEW
HOURS. AFTER CONVECTIVE BOUNDARIES MOVE ACROSS WINDS SHOULD
GRADUALLY SHIFT BACK TO MORE SSW BY 06Z. OVERNIGHT LOOKS LIKE A A
SHIFT TO NLY WINDS WILL OCCUR IN THE 12Z-15Z TIMEFRAME ON MON AS
A COOL FRONT MOVE ACROSS. AT THIS TIME NO LOW CLOUDS ARE EXPECTED
WITH THIS FEATURE. WILL SEE MORE CONVECTIVE ACTIVITY MONDAY AROUND
THE AIRPORTS.
PREV DISCUSSION... /ISSUED 406 AM MDT SUN SEP 8 2013/
SHORT TERM...THE STUBBORN UPPER LEVEL RIDGE WILL FINALLY BEGIN TO
SHIFT EASTWARD AS AN UPPER LEVEL TROUGH MOVES INTO THE NRN
ROCKIES BY TONIGHT. INFLUX OF SUBTROPICAL MOISTURE WILL REMAIN IN
THE MTNS AND ACROSS THE NRN FOOTHILLS THRU TONIGHT WITH SCT TSTMS
DEVELOPING BY AFTN. ELSEWHERE OUTFLOW BOUNDARIES FM CONVECTION
OVER THE HIGHER TERRAIN MAY SWEEP ACROSS THE FRONT RANGE BY LATE
AFTN INTO THE EARLY EVENING HOURS ALLOWING FOR SOME ISOLD TO WDLY
SCT HIGHER BASED STORMS TO DVLP. AS FOR HIGHS ONE MORE AFTN FOR 90
DEGREE PLUS READINGS OVER NERN CO. RECORD AT DENVER IS 94 DEGREES
WHICH COULD BE TIED OR BKN DEPENDING ON TIMING OF MID LVL CLOUD
COVER THIS AFTN.
FOR TONIGHT EXPECT SOME LINGERING SHOWERS AND A FEW STORMS IN THE
MTNS OVERNIGHT AS SUBTROPICAL MOISTURE FEED CONTINUES. OVER NERN CO
ISOLD-WDLY SCT TSTM ACTIVITY ALONG THE FRONT RANGE SHOULD END BEFORE
06Z. BY LATE TONIGHT A COOL FRONT WILL BEGIN TO MOVE SOUTH INTO
NERN CO WITH NLY WINDS DEVELOPING TOWARDS SUNRISE.
LONG TERM...MODELS CONTINUE TO SHOW A SHIFT IN THE UPPER FLOW
PATTERN THAT WILL BRING A FEW DAYS OF RAINFALL TO PARTS OF NORTH-
CENTRAL AND NORTHEAST COLORADO. THE UPPER RIDGE THAT DOMINATED
COLORADO WEATHER THIS PAST WEEK WITH RECORD BREAKING TEMPERATURES
WILL CONTINUE MOVING EASTWARD AND WEAKENING FOR THE NEXT 48-60
HOURS AS AN UPPER TROUGH MOVES OVER THE NORTHERN ROCKIES AND TO
THE CANADIAN PRARIES. OVER COLORADO...THE FLOW OF MID-LEVEL
SUBTROPICAL MOISTURE IS EXPECTED TO STRENGTHEN. THIS WILL LEAD TO
AN INCREASE IN SHOWER ACTIVITY OVER THE MOUNTAINS WHICH WILL ALSO
EXTEND ONTO THE NORTHEAST COLORADO PLAINS. TUESDAY LOOKS LIKE IT
IS GOING TO BE THE COOLEST DAY OF THE WEEK DUE TO A SURGE OF COOL
AIR COMING INTO THE STATE FROM THE NORTH MONDAY NIGHT. THE AIRMASS
MAY ALSO BE COOLED SOME BY THE RAINFALL FROM MONDAY NIGHT. SHOWER
ACTIVITY MONDAY EVENING IS GOING TO BE ENHANCED BY A WEAK UPPER
LEVEL JET ASSOCIATED WITH THE NORTHERN ROCKIES TROUGH THAT WILL
BE IN PLACE OVER WYOMING. EACH OF THE MODELS INDICATE THAT SHOWERS
OVER THE FORECAST AREA COULD LAST THROUGH MOST OF MONDAY NIGHT.
ONCE THE UPPER LEVEL PATTERN SHIFTS TO MOIST AND SOUTH-
SOUTHWESTERLY ON MONDAY...IT WILL REMAIN IN PLACE MOST OF THE
WEEK. SHOWERS ARE EXPECTED TO KEEP GENERATING EACH DAY AS
SUBTROPICAL MOISTURE CONTINUES MOVING INTO THE STATE. AT THIS TIME
IT IS DIFFICULT TO TELL IF ANY OF THE DAYS WILL HAVE PARTICULARLY
HEAVY RAINFALL...SO WILL JUST KEEP AN EYE ON THE MODEL RUNS AS
THEY KEEP COMING IN. MODEL SOUNDINGS SHOW THAT PRECIPITABLE WATER
VALUES WILL INITIALLY RISE TO THE 1.00 TO 1.10 INCH RANGE WHICH IS
NOT THAT ABNORMAL FOR THE LATE SUMMER. THE FORECAST PACKAGE DID
NOT NEED THAT MUCH ADJUSTMENT THIS TIME AROUND.
AVIATION...DRAINAGE WINDS EARLY THIS MORNING MAY BECOME LIGHT AND
VARIABLE BY 14Z AND LINGER THRU 18Z. BY EARLY AFTN WINDS WILL
BECOME MORE SSE. LAST FEW RUNS OF THE RAP SHOWS A RATHER STG
OUTFLOW BNDRY COMING OUT OF THE FOOTHILLS AND ACROSS DIA IN THE
00Z-01Z TIME PERIOD ALONG WITH SOME ISOLD HIGHER BASED STORMS SO
WILL MENTION VCTS WITH A TEMPO GROUP FOR GUSTY OUTFLOW WINDS FOR A
FEW HOURS. AFTER CONVECTIVE BOUNDARIES MOVE ACROSS WINDS SHOULD
GRADUALLY SHIFT BACK TO MORE SSW BY 06Z. OVERNIGHT LOOKS LIKE A
A SHIFT TO NLY WINDS WILL OCCUR IN THE 12Z-15Z TIMEFRAME ON MON AS
A COOL FRONT MOVE ACROSS. AT THIS TIME NO LOW CLOUDS ARE EXPECTED
WITH THIS FEATURE.
HYDROLOGY...WILL SEE SCATTERED STORMS IN THE MTNS AND NRN
FOOTHILLS THIS AFTN ALTHOUGH THE FLOW ALOFT WILL BE A BIT STRONGER
SO THEY SHOULD MOVE ALONG. RAINFALL AMOUNTS WILL BE LESS THAN ONE
HALF INCH HOWEVER UP TO AN INCH COULD OCCUR WITH ANY STRONGER
STORM.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1107 AM MDT SUN SEP 8 2013
.UPDATE...STRONG SOUTHERLY WINDS ARE SURFACING OVER THE FAR
EASTERN PLAINS WITH GUSTS TO 35 MPH. HUMIDITIES ARE IN THE UPPER
TEENS TO LOWER 20 PERCENT RANGE AND ARE NOT EXPECTED TO DROP MUCH
MORE. THERE MAY BE A FEW SPOTTY AREAS THAT HIT WARNING
CRITERIA...BUT NOT FOR LONG.
BUILDING CUMULUS OVER THE HIGH TERRAIN WILL CONTINUE WITH
SCATTERED STORMS THIS AFTERNOON. EXPECTING SLIGHTLY MORE MOISTURE
BUT STORMS WILL BE MOVING QUICKER TODAY.
ONLY MADE MINOR ADJUSTMENTS TO TEMPERATURES AND WINDS IN THE
GRIDS FOR THE MORNING UPDATE.
&&
.AVIATION...WINDS ARE BECOMING TRICKY FOR THE AREA AIRPORTS.
NORTHERLY WINDS ARE STICKING AROUND LONGER WITH THE EDGE OF
SOUTHERLY WINDS BEGINNING TO SHOW UP ON RADAR OVER FAR EASTERN
ADAMS AND ARAPAHOE COUNTIES. KEEP PUSHING OFF THE SOUTHEAST WINDS
UNTIL LATER. LAST FEW RUNS OF THE RAP SHOWS A RATHER STG OUTFLOW
BNDRY COMING OUT OF THE FOOTHILLS AND ACROSS DIA IN THE 22Z-00Z
TIME PERIOD ALONG WITH SOME ISOLD HIGHER BASED STORMS SO BACK UP
THE TIMING OF THE TEMPO GROUP FOR GUSTY OUTFLOW WINDS FOR A FEW
HOURS. AFTER CONVECTIVE BOUNDARIES MOVE ACROSS WINDS SHOULD
GRADUALLY SHIFT BACK TO MORE SSW BY 06Z. OVERNIGHT LOOKS LIKE A A
SHIFT TO NLY WINDS WILL OCCUR IN THE 12Z-15Z TIMEFRAME ON MON AS
A COOL FRONT MOVE ACROSS. AT THIS TIME NO LOW CLOUDS ARE EXPECTED
WITH THIS FEATURE. WILL SEE MORE CONVECTIVE ACTIVITY MONDAY AROUND
THE AIRPORTS.
&&
.PREV DISCUSSION... /ISSUED 406 AM MDT SUN SEP 8 2013/
SHORT TERM...THE STUBBORN UPPER LEVEL RIDGE WILL FINALLY BEGIN TO
SHIFT EASTWARD AS AN UPPER LEVEL TROUGH MOVES INTO THE NRN
ROCKIES BY TONIGHT. INFLUX OF SUBTROPICAL MOISTURE WILL REMAIN IN
THE MTNS AND ACROSS THE NRN FOOTHILLS THRU TONIGHT WITH SCT TSTMS
DEVELOPING BY AFTN. ELSEWHERE OUTFLOW BOUNDARIES FM CONVECTION
OVER THE HIGHER TERRAIN MAY SWEEP ACROSS THE FRONT RANGE BY LATE
AFTN INTO THE EARLY EVENING HOURS ALLOWING FOR SOME ISOLD TO WDLY
SCT HIGHER BASED STORMS TO DVLP. AS FOR HIGHS ONE MORE AFTN FOR 90
DEGREE PLUS READINGS OVER NERN CO. RECORD AT DENVER IS 94 DEGREES
WHICH COULD BE TIED OR BKN DEPENDING ON TIMING OF MID LVL CLOUD
COVER THIS AFTN.
FOR TONIGHT EXPECT SOME LINGERING SHOWERS AND A FEW STORMS IN THE
MTNS OVERNIGHT AS SUBTROPICAL MOISTURE FEED CONTINUES. OVER NERN CO
ISOLD-WDLY SCT TSTM ACTIVITY ALONG THE FRONT RANGE SHOULD END BEFORE
06Z. BY LATE TONIGHT A COOL FRONT WILL BEGIN TO MOVE SOUTH INTO
NERN CO WITH NLY WINDS DEVELOPING TOWARDS SUNRISE.
LONG TERM...MODELS CONTINUE TO SHOW A SHIFT IN THE UPPER FLOW
PATTERN THAT WILL BRING A FEW DAYS OF RAINFALL TO PARTS OF NORTH-
CENTRAL AND NORTHEAST COLORADO. THE UPPER RIDGE THAT DOMINATED
COLORADO WEATHER THIS PAST WEEK WITH RECORD BREAKING TEMPERATURES
WILL CONTINUE MOVING EASTWARD AND WEAKENING FOR THE NEXT 48-60
HOURS AS AN UPPER TROUGH MOVES OVER THE NORTHERN ROCKIES AND TO
THE CANADIAN PRARIES. OVER COLORADO...THE FLOW OF MID-LEVEL
SUBTROPICAL MOISTURE IS EXPECTED TO STRENGTHEN. THIS WILL LEAD TO
AN INCREASE IN SHOWER ACTIVITY OVER THE MOUNTAINS WHICH WILL ALSO
EXTEND ONTO THE NORTHEAST COLORADO PLAINS. TUESDAY LOOKS LIKE IT
IS GOING TO BE THE COOLEST DAY OF THE WEEK DUE TO A SURGE OF COOL
AIR COMING INTO THE STATE FROM THE NORTH MONDAY NIGHT. THE AIRMASS
MAY ALSO BE COOLED SOME BY THE RAINFALL FROM MONDAY NIGHT. SHOWER
ACTIVITY MONDAY EVENING IS GOING TO BE ENHANCED BY A WEAK UPPER
LEVEL JET ASSOCIATED WITH THE NORTHERN ROCKIES TROUGH THAT WILL
BE IN PLACE OVER WYOMING. EACH OF THE MODELS INDICATE THAT SHOWERS
OVER THE FORECAST AREA COULD LAST THROUGH MOST OF MONDAY NIGHT.
ONCE THE UPPER LEVEL PATTERN SHIFTS TO MOIST AND SOUTH-
SOUTHWESTERLY ON MONDAY...IT WILL REMAIN IN PLACE MOST OF THE
WEEK. SHOWERS ARE EXPECTED TO KEEP GENERATING EACH DAY AS
SUBTROPICAL MOISTURE CONTINUES MOVING INTO THE STATE. AT THIS TIME
IT IS DIFFICULT TO TELL IF ANY OF THE DAYS WILL HAVE PARTICULARLY
HEAVY RAINFALL...SO WILL JUST KEEP AN EYE ON THE MODEL RUNS AS
THEY KEEP COMING IN. MODEL SOUNDINGS SHOW THAT PRECIPITABLE WATER
VALUES WILL INITIALLY RISE TO THE 1.00 TO 1.10 INCH RANGE WHICH IS
NOT THAT ABNORMAL FOR THE LATE SUMMER. THE FORECAST PACKAGE DID
NOT NEED THAT MUCH ADJUSTMENT THIS TIME AROUND.
AVIATION...DRAINAGE WINDS EARLY THIS MORNING MAY BECOME LIGHT AND
VARIABLE BY 14Z AND LINGER THRU 18Z. BY EARLY AFTN WINDS WILL
BECOME MORE SSE. LAST FEW RUNS OF THE RAP SHOWS A RATHER STG
OUTFLOW BNDRY COMING OUT OF THE FOOTHILLS AND ACROSS DIA IN THE
00Z-01Z TIME PERIOD ALONG WITH SOME ISOLD HIGHER BASED STORMS SO
WILL MENTION VCTS WITH A TEMPO GROUP FOR GUSTY OUTFLOW WINDS FOR A
FEW HOURS. AFTER CONVECTIVE BOUNDARIES MOVE ACROSS WINDS SHOULD
GRADUALLY SHIFT BACK TO MORE SSW BY 06Z. OVERNIGHT LOOKS LIKE A
A SHIFT TO NLY WINDS WILL OCCUR IN THE 12Z-15Z TIMEFRAME ON MON AS
A COOL FRONT MOVE ACROSS. AT THIS TIME NO LOW CLOUDS ARE EXPECTED
WITH THIS FEATURE.
HYDROLOGY...WILL SEE SCATTERED STORMS IN THE MTNS AND NRN
FOOTHILLS THIS AFTN ALTHOUGH THE FLOW ALOFT WILL BE A BIT STRONGER
SO THEY SHOULD MOVE ALONG. RAINFALL AMOUNTS WILL BE LESS THAN ONE
HALF INCH HOWEVER UP TO AN INCH COULD OCCUR WITH ANY STRONGER
STORM.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
UPDATE/AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1106 AM MDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 1106 AM MDT SUN SEP 8 2013
MADE A FEW TWEAKS DOWNWARD TO TEMPERATURE FORECAST MAINLY ACROSS
THE WESTERN CWA WITH THICKER CLOUD COVER IN PLACE. MORNING
SATELLITE AND RADAR IMAGERY SUGGESTS A WAVE MOVING INTO THE 4
CORNERS ATTM AND THIS ALONG WITH HEATING FROM THE DAY SHOULD BEGIN
TO SPARK CONVECTION. THE MAIN FOCUS WILL BE OVER THE WESTERN CWA
NOT ONLY DUE TO THE GOOD MOISTURE PLUME BUT ADDED ASCENT FROM THE
WAVE AND FAVORABLE UPPER LEVEL JET LOCATION. SHOWERS SHOULD ALSO
FAVOR THE EASTERN TERRAIN EARLY IN THE AFTERNOON THEN MOVE TO THE
VALLEYS THROUGH BY EVENING WITH STORM MOTIONS FROM THE SOUTH
AROUND 15 TO 20 MPH. PWATS AT GJT ARE NEAR 200 PERCENT OF NORMAL
AND WITH WARM CLOUD DEPTHS RUNNING AOA 8000 FT...HEAVY RAINFALL
WILL BE A GOOD BET. TRAINING OF CELLS WILL BRING A THREAT OF FLASH
FLOODING OVER OUR SOUTHWEST CWA AND FLASH FLOOD WATCH IS NOW IN
EFFECT.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 353 AM MDT SUN SEP 8 2013
PATTERN SHIFT UNDERWAY ACROSS THE WESTERN U.S. AS THE CLOSED LOW
OVER THE PACNW FINALLY KICKS EAST. THIS WILL ALLOW THE DEEP
MONSOONAL PLUME THAT HAS BEEN PARKED JUST TO OUR WEST...TO SHIFT
EAST AND SOUTH OVER OUR AREA FOR THE NEXT FEW DAYS. SEVERAL
EMBEDDED WAVES WITHIN THE FLOW WILL ENHANCE CONVECTION AND TEAM
WITH THE NUMEROUS OUTFLOW BOUNDARIES ROAMING THE FORECAST AREA TO
TRIGGER AN INCREASE IN CONVECTION THIS AFTERNOON. POTENTIAL FOR
HEAVY RAIN DEFINITELY ON THE INCREASE WITH MODEL PRECIPITABLE
WATER FORECAST JUMPING TO OVER AN INCH THIS AFTERNOON AND PEAK
AROUND 1.40 INCHES BY EARLY MONDAY MORNING. EXPECT ENOUGH BREAKS
IN CLOUD COVER TODAY TO ALLOW A FEW STRONGER STORMS TO FIRE WITH
THE HRRR DEVELOPING DEEPER CONVECTION AFTER 18Z ACROSS SOUTHEAST
UTAH. STORM MOTION WILL REMAIN FAIRLY SLOW AND POTENTIAL FOR SOME
TRAINING EXISTS. FOCUS OF ATTENTION THROUGH THIS AFTERNOON WILL BE
THE CANYON COUNTRY IN SOUTHEAST UTAH AND CLOSE TO LAKE POWELL IN
SAN JUAN COUNTY UTAH...ALTHOUGH ANY STORMS THAT FIRE WILL BE
CAPABLE OF PRODUCING HEAVY RAINFALL. CONFIDENCE INCREASING THAT
WE WILL BE HAVING SOME FLASH FLOOD PROBLEMS BEGINNING THIS
AFTERNOON AND CONTINUING THROUGH MONDAY EVENING. AS A
RESULT...WILL BE ISSUING A FLASH FLOOD WATCH FOR EAST CENTRAL AND
SOUTHEAST UTAH AND PORTIONS OF SOUTHWEST COLORADO...MAINLY FOR THE
BEDROCK AND SLICK ROCK AREAS NORTH OF CORTEZ AND SOUTH OF
GATEWAY. WITH CLOUD COVER AND GREATER SFC MOISTURE IN
PLACE...TEMPS DROP AT LEAST 5 DEGREES ACROSS THE BOARD...BRINGING
AN END TO THE RECENT STRETCH OF 90 PLUS DAYS IN GRAND JUNCTION.
A WET WEEK IS IN STORE FOR THE REGION WITH THE EASTERN UTAH AND
THE SOUTHERN SLOPES OF OF THE SOUTHERN AND CENTRAL MOUNTAINS
FAVORED FOR HEAVY RAINFALL. MODELS REMAIN IN GOOD AGREEMENT.
SUNDAY NIGHT INTO MONDAY THE PACIFIC UPPER LOW TRACKS THROUGH THE
NORTHERN ROCKIES AND ONTO THE NORTHERN PLAINS LEAVING A VERTICALLY
STACKED TROUGH IN THE GREAT BASIN CENTERED OVER LAS VEGAS. THIS
PRODUCES ENHANCES S-SW MOIST AND PERTURBED FLOW INTO EASTERN UTAH.
PRECIPITABLE WATER SURGES TO 1.4 INCHES IN SE UTAH TO OVER AN INCH
NORTH OF CRAIG. STORM MOTION IS TO THE NE AT 20KTS WHICH WILL
LIMIT RAINFALL FROM ANY ONE STORM BUT TRAINING WILL QUICKLY ADD
UP. DIVERGENCE ALOFT IN THE RIGHT ENTRANCE REGION OF A WEAK 40KT
JET OVER NE UTAH- FAR NW CO WILL ENHANCE SHOWERS THERE. CLOUDS
AND SHOWERS WILL DROP MONDAY TEMPERATURES BELOW NORMAL FOR THE
FIRST TIME THIS MONTH.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 353 AM MDT SUN SEP 8 2013
SOME CHANGES IN STORE IN THE PATTERN THROUGH TUESDAY NIGHT BUT
WIDESPREAD SHOWERS AND STORMS WILL CONTINUE. EAST LOW LEVEL FLOW
SETS UP MONDAY NIGHT THAT MAY LIMIT RAINFALL AMOUNTS. BUT WEAK
COLD ADVECTION ALOFT MAY PRODUCE ENOUGH FORCING TO OVERCOME THIS.
MODELS ARE NOW PRODUCING SOME LIGHT SNOWFALL ABOVE TIMBERLINE
ESPECIALLY MONDAY NIGHT. DIVERGENCE ALOFT REMAINS OVER NE UTAH.
TUESDAY THE REMNANTS OF WHAT WAS TS LORENA...CURRENTLY ALONG THE
SOUTHERN BAJA... WILL BE PULLED INTO FOUR CORNERS ENHANCING
ALREADY DEEP MOISTURE. STORM MOTION OF TO THE NORTH AT 15-20 MPH
WILL AGAIN MAKE FLOODING DIFFICULT FROM ANY ONE STORM...BUT MUD
FLOWS WILL THREATEN FROM TWO DAYS OF HEAVY RAIN ESPECIALLY ALONG
SOUTH FACING SLOPES. SCATTERED TO WIDESPREAD STORMS CONTINUE INTO
WEDNESDAY MORNING.
MOIST AND UNSETTLED CONDITIONS REMAIN IN PLACE THROUGH THURSDAY AS
REMNANTS OF TROPICAL STORM LORENA CONTINUE TO PUSH NORTHEAST THROUGH
THE FORECAST AREA. THIS WILL KEEP THE POTENTIAL FOR HEAVY RAIN IN
THE FORECAST. SUBTLE DRYING ADVERTISED IN THE MOST RECENT MEDIUM
RANGE MODELS AS WE CLOSE OUT THE WORK WEEK. HOWEVER...ANOTHER
PACIFIC TROUGH SWINGS INLAND OVER THE WEEKEND AND WILL DRAW UP AT
LEAST ONE MORE ROUND MONSOONAL MOISTURE. TEMPERATURES WILL BE
RUNNING NEAR SEASONAL NORMS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1106 AM MDT SUN SEP 8 2013
VFR CONDITIONS WILL BE PREVAILING TO START OUT THE AFTERNOON ACROSS
ALL OF THE FORECAST TERMINALS. HOWEVER AS THE AFTERNOON MOVES INTO
EVENING SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD.
HEAVY RAINFALL AND GUSTY WINDS WILL BE THE MAIN THREAT TO THE
FORECAST TERMINALS WHERE LOWERED FLIGHT CRITERIA MAY TEMPORARILY
SET UP. IN ELEVATIONS ABOVE 9500 FEET...MOUNTAIN OBSCURATIONS WILL
BECOME MORE LIKELY INTO THE OVERNIGHT HOURS AND A FEW STORMS MAY BE
ABLE TO DROP SOME SMALL HAIL. UNSETTLED CONDITIONS WILL CONTINUE
THROUGH THE OVERNIGHT HOURS AND INTO MUCH OF MONDAY AS A STRONG
PLUME OF MOISTURE SETTLES OVER WESTERN COLORADO AND EASTERN UTAH.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR COZ020-021.
UT...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR UTZ022-025-027>029.
&&
$$
UPDATE...15
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...TGJT
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1059 AM MDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1057 AM MDT SAT SEP 7 2013
AN AREA OF LIGHT SHOWERS WITH A LIGHTNING STRIKE EVERY SO
OFTEN...CONTINUES TO MOVE NORTH ACROSS NORTHWEST COLORADO THIS
MORNING. THIS ACTIVITY WAS LOCATED FROM THE VICINITY OF THE
CATHEDRAL BLUFFS IN WESTERN RIO BLANCO COUNTY TO WEST OF HIGHWAY
13 FROM HAMILTON/CRAIG TO BAGGS WY LATE THIS MORNING. THESE
SHOWERS WILL CONTINUE NORTHWARD INTO WY BY NOON OR SHORTLY
THEREAFTER. OTHERWISE CONVECTION IS JUST STARTING TO BUILDUP OVER
THE HIGHER TERRAIN WITH THAT TREND EXPECTED TO CONTINUE INTO THE
AFTERNOON AS PER PREVIOUS FORECAST.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
ISOLATED THUNDERSTORMS FIRING ACROSS PORTIONS OF NORTHEAST ARIZONA
THIS MORNING...BASICALLY SOUTH OF MEXICAN HAT...AND ALONG THE
UNCOMPAHGRE PLATEAU SOUTH AND EAST OF GATEWAY. THE ARIZONA
ACTIVITY APPEARS TO BE ASSOCIATED WITH WEAK WAVE LIFTING NORTH
NORTHWEST ACROSS THAT AREA...WHICH SHOWS UP NICELY IN POT VORT
FIELDS ON THE 00Z NAM AND GFS. THIS WAVE WILL CONTINUE TRACKING
TOWARD THE FOUR CORNERS THIS MORNING...BEFORE DAMPENING OUT
SHORTLY AFTER SUNRISE.
THE CELLS EAST OF GATEWAY ALONG THE UNCOMPAHGRE PLATEAU APPEAR TO
BE FIRING ALONG AN OLD OUTFLOW BOUNDARY FROM LAST EVENING THAT WAS
EVIDENT ON RADAR IMAGERY EARLIER THIS MORNING. LIGHTNING ACTIVITY
HAS BEEN ON THE INCREASE OVER THE PAST HOUR AND LIKELY WILL
CONTINUE FOR ANOTHER COUPLE HOURS.
HRRR DOING A DECENT JOB WITH PICKING UP THIS ACTIVITY AND DRIVING
IT NW AND N THIS MORNING...ENDING AROUND 14Z OR SHORTLY AFTER
SUNRISE. THIS SOLUTION REASONABLE AND WILL GEAR POPS IN THIS
DIRECTION...BUT BACK OFF AREAL COVERAGE DISPLAYED IN THE HRRR AS
IT APPEARS TO BE A BIT AGGRESSIVE ACROSS SE UTAH. ONCE THIS
ACTIVITY DIMINISHES...WILL TAKE A FEW HOURS TO RE-FIRE
CONVECTION...BUT IT WILL AND FOCUS FOR THE AFTERNOON HOURS WILL BE
ACROSS THE HIGHER TERRAIN AND PORTIONS OF SOUTHEAST UTAH AS THE
DEEPER PLUME NUDGES EAST A BIT AS THE UPPER LOW ACROSS THE PACNW
STARTS TO FEEL THE INFLUENCE OF KICKING SYSTEM MOVING INTO WESTERN
CANADA. THINGS GET A LOT MORE INTERESTING SUNDAY AND MONDAY...
WHICH IS DISCUSSED BELOW AS THE PLUME LEANS OVER AND INTO OUR
FORECAST AREA. UNTIL THEN...ANOTHER HOT DAY WITH TEMPERATURES
RUNNING 5 TO 10 DEGREES ABOVE NORMAL FOR AFTERNOON HIGHS.
TONIGHT THE UPPER LOW TRACKS INTO THE NORTHERN ROCKIES DRAGGING A
TROUGH INTO THE WESTERN GREAT BASIN. IN TIGHTENING SW FLOW
ALOFT...MOISTURE AND LOW LEVEL CONVERGENCE INCREASE IN SE UTAH
OVERNIGHT. SO SOME THUNDERSTORMS ARE EXPECTED TO PERSIST OVERNIGHT
PERHAPS SPREADING INTO NE UTAH AND FAR WESTERN COLORADO. CLOUDS
AND WINDS WILL KEEP OVERNIGHT LOW TEMPERATURES ABOVE NORMAL.
SUNDAY THE PACIFIC TROUGH SHIFTS INTO CENTRAL UTAH. ONE INCH
PRECIPITABLE WATER VALUES REACH INTO THE NORTHERN CWA. A WEAK
SURFACE COLD FRONT WORKS ACROSS THE CO-WY BORDER IN THE AFTERNOON
PROVIDING A FOCUS FOR CONVECTION. WIDESPREAD CLOUDY SKIES WILL
LOWER AFTERNOON TEMPERATURES TO WITHIN A FEW DEGREES OF NORMAL.
GUSTY AFTERNOON WINDS EXPECTED DUE TO GRADIENT PLUS CONVECTIVE
COMPONENTS. SOME MID-LEVEL COOLING WILL INCREASE INSTABILITY
ESPECIALLY OVER NE UT-FAR NW CO.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
SUNDAY NIGHT THROUGH MONDAY NIGHT...THE UPPER LOW TRACKS ONTO THE
NORTHERN PLAINS ON MONDAY LEAVING A WEAK TROUGH OVER THE GREAT
BASIN. THE 40KT JET TAIL TRACKS THROUGH SOUTHERN WYOMING SUNDAY
NIGHT LEAVING A SECOND STRONGER COOL FRONT LAYING WEST TO EAST
NEAR THE WYOMING BORDER ON MONDAY. WITH THE WET BULB ZERO LEVEL
BELOW 14KFT...HAIL IS POSSIBLE WITH THE STRONGEST STORMS.
TEMPERATURES FALL TO NEAR/SOUTH OR BELOW/NORTH NORMAL ON MONDAY.
DRIER AIR TRIES TO INVADE NE UTAH MONDAY NIGHT.
THE STAGNANT RIDGE OVER THE PLAINS AND LOW ACROSS THE PACNW
PATTERN WILL BE BREAKING DOWN MONDAY AND TUESDAY...WITH LONG WAVE
TROUGH FINALLY PUSHING EAST ACROSS THE ROCKIES. THIS WILL DRIVE A
LITTLE COOLER AIR INTO THE REGION AS TEMPERATURES DROP BACK TO
MORE SEASONAL VALUES. HOWEVER...CONVECTIVE POTENTIAL WILL REMAIN
IN PLAY FOR MUCH OF THE WEEK AS THE BREAK DOWN AND SWEEP OUT OF
MOISTURE WILL BE SHORT-LIVED WITH THE PLAINS RIDGE REBUILDING BY
THURSDAY. THIS KEEPS THE MONSOON ACTIVE FOR A FEW MORE DAYS WITH
ANOTHER SURGE OF MOISTURE LIFTING ACROSS THE FORECAST AREA AS WE
CLOSE OUT THE WEEK. SO UNSETTLED CONDITIONS WILL CONTINUE WITH
SLIGHTLY MODERATION FROM THE PERSISTENT HEAT THE REGION HAS BEEN
EXPERIENCING.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1057 AM MDT SAT SEP 7 2013
ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
WILL DEVELOP THIS AFTERNOON...FAVORING THE HIGHER TERRAIN. GUSTY
AND ERRATIC OUTFLOW WINDS...HEAVY RAIN AND SMALL HAIL WILL BE
ASSOCIATED WITH THE STRONGER THUNDERSTORMS THROUGH 03Z THIS
EVENING. MOISTURE WILL CONTINUE TO SURGE BACK INTO THE REGION
AFTER 06Z TONIGHT WITH SHOWERS LINGERING THROUGH THE NIGHT. EXPECT
LOCAL MVFR CIGS AND VSBYS NEAR THE STRONGER THUNDERSTORMS THIS
AFTERNOON...ESPECIALLY ACROSS THE MOUNTAINS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...EH
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...EH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
359 AM MDT SAT SEP 7 2013
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
ISOLATED THUNDERSTORMS FIRING ACROSS PORTIONS OF NORTHEAST ARIZONA
THIS MORNING...BASICALLY SOUTH OF MEXICAN HAT...AND ALONG THE
UNCOMPAHGRE PLATEAU SOUTH AND EAST OF GATEWAY. THE ARIZONA ACTIVITY
APPEARS TO BE ASSOCIATED WITH WEAK WAVE LIFTING NORTH NORTHWEST
ACROSS THAT AREA...WHICH SHOWS UP NICELY IN POT VORT FIELDS ON THE
00Z NAM AND GFS. THIS WAVE WILL CONTINUE TRACKING TOWARD THE FOUR
CORNERS THIS MORNING...BEFORE DAMPENING OUT SHORTLY AFTER SUNRISE.
THE CELLS EAST OF GATEWAY ALONG THE UNCOMPAHGRE PLATEAU APPEAR TO
BE FIRING ALONG AN OLD OUTFLOW BOUNDARY FROM LAST EVENING THAT WAS
EVIDENT ON RADAR IMAGERY EARLIER THIS MORNING. LIGHTNING ACTIVITY
HAS BEEN ON THE INCREASE OVER THE PAST HOUR AND LIKELY WILL
CONTINUE FOR ANOTHER COUPLE HOURS.
HRRR DOING A DECENT JOB WITH PICKING UP THIS ACTIVITY AND DRIVING
IT NW AND N THIS MORNING...ENDING AROUND 14Z OR SHORTLY AFTER
SUNRISE. THIS SOLUTION REASONABLE AND WILL GEAR POPS IN THIS
DIRECTION...BUT BACK OFF AREAL COVERAGE DISPLAYED IN THE HRRR AS
IT APPEARS TO BE A BIT AGGRESSIVE ACROSS SE UTAH. ONCE THIS
ACTIVITY DIMINISHES...WILL TAKE A FEW HOURS TO RE-FIRE
CONVECTION...BUT IT WILL AND FOCUS FOR THE AFTERNOON HOURS WILL BE
ACROSS THE HIGHER TERRAIN AND PORTIONS OF SOUTHEAST UTAH AS THE
DEEPER PLUME NUDGES EAST A BIT AS THE UPPER LOW ACROSS THE PACNW
STARTS TO FEEL THE INFLUENCE OF KICKING SYSTEM MOVING INTO WESTERN
CANADA. THINGS GET A LOT MORE INTERESTING SUNDAY AND MONDAY...
WHICH IS DISCUSSED BELOW AS THE PLUME LEANS OVER AND INTO OUR
FORECAST AREA. UNTIL THEN...ANOTHER HOT DAY WITH TEMPERATURES
RUNNING 5 TO 10 DEGREES ABOVE NORMAL FOR AFTERNOON HIGHS.
TONIGHT THE UPPER LOW TRACKS INTO THE NORTHERN ROCKIES DRAGGING A
TROUGH INTO THE WESTERN GREAT BASIN. IN TIGHTENING SW FLOW
ALOFT...MOISTURE AND LOW LEVEL CONVERGENCE INCREASE IN SE UTAH
OVERNIGHT. SO SOME THUNDERSTORMS ARE EXPECTED TO PERSIST OVERNIGHT
PERHAPS SPREADING INTO NE UTAH AND FAR WESTERN COLORADO. CLOUDS
AND WINDS WILL KEEP OVERNIGHT LOW TEMPERATURES ABOVE NORMAL.
SUNDAY THE PACIFIC TROUGH SHIFTS INTO CENTRAL UTAH. ONE INCH
PRECIPITABLE WATER VALUES REACH INTO THE NORTHERN CWA. A WEAK
SURFACE COLD FRONT WORKS ACROSS THE CO-WY BORDER IN THE AFTERNOON
PROVIDING A FOCUS FOR CONVECTION. WIDESPREAD CLOUDY SKIES WILL
LOWER AFTERNOON TEMPERATURES TO WITHIN A FEW DEGREES OF NORMAL.
GUSTY AFTERNOON WINDS EXPECTED DUE TO GRADIENT PLUS CONVECTIVE
COMPONENTS. SOME MID-LEVEL COOLING WILL INCREASE INSTABILITY
ESPECIALLY OVER NE UT-FAR NW CO.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
SUNDAY NIGHT THROUGH MONDAY NIGHT...THE UPPER LOW TRACKS ONTO THE
NORTHERN PLAINS ON MONDAY LEAVING A WEAK TROUGH OVER THE GREAT
BASIN. THE 40KT JET TAIL TRACKS THROUGH SOUTHERN WYOMING SUNDAY
NIGHT LEAVING A SECOND STRONGER COOL FRONT LAYING WEST TO EAST NEAR
THE WYOMING BORDER ON MONDAY. WITH THE WET BULB ZERO LEVEL BELOW
14KFT...HAIL IS POSSIBLE WITH THE STRONGEST STORMS. TEMPERATURES
FALL TO NEAR/SOUTH OR BELOW/NORTH NORMAL ON MONDAY. DRIER AIR
TRIES TO INVADE NE UTAH MONDAY NIGHT.
THE STAGNANT RIDGE OVER THE PLAINS AND LOW ACROSS THE PACNW
PATTERN WILL BE BREAKING DOWN MONDAY AND TUESDAY...WITH LONG WAVE
TROUGH FINALLY PUSHING EAST ACROSS THE ROCKIES. THIS WILL DRIVE A
LITTLE COOLER AIR INTO THE REGION AS TEMPERATURES DROP BACK TO
MORE SEASONAL VALUES. HOWEVER...CONVECTIVE POTENTIAL WILL REMAIN
IN PLAY FOR MUCH OF THE WEEK AS THE BREAK DOWN AND SWEEP OUT OF
MOISTURE WILL BE SHORT-LIVED WITH THE PLAINS RIDGE REBUILDING BY
THURSDAY. THIS KEEPS THE MONSOON ACTIVE FOR A FEW MORE DAYS WITH
ANOTHER SURGE OF MOISTURE LIFTING ACROSS THE FORECAST AREA AS WE
CLOSE OUT THE WEEK. SO UNSETTLED CONDITIONS WILL CONTINUE WITH
SLIGHTLY MODERATION FROM THE PERSISTENT HEAT THE REGION HAS BEEN
EXPERIENCING.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 358 AM MDT SAT SEP 7 2013
ISOLATED THUNDERSTORMS WILL CONTINUE THROUGH THIS MORNING...AND
BECOME MORE WIDESPREAD THIS AFTERNOON. GUSTY AND ERRATIC OUTFLOW
WINDS...HEAVY RAIN AND SMALL HAIL WILL BE ASSOCIATED WITH STRONGER
THUNDERSTORMS THROUGH 03Z THIS EVENING. MOISTURE WILL CONTINUE
TO SURGE BACK INTO THE REGION AFTER 06Z TONIGHT WITH SHOWERS
LINGERING THROUGH THE NIGHT. EXPECT LOCAL MVFR CIGS AND VSBYS NEAR
THE STRONGER THUNDERSTORMS TODAY...ESPECIALLY ACROSS THE
MOUNTAINS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS ALBANY NY
1025 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF THE EASTERN SEABOARD TODAY. THE
SOUTHERLY FLOW AROUND THIS HIGH PRESSURE AREA WILL RESULT IN A
MILDER DAY TODAY. A COLD FRONT WILL CROSS THE REGION LATE TONIGHT
AND EARLY SUNDAY MORNING WITH THE CHANCE FOR SOME RAIN SHOWERS...
FOLLOWED BY BREEZY AND COOLER CONDITIONS BEHIND IT FOR THE REST OF
SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM EDT...CLOUD SHIELD CONTINUES TO ADVANCE EASTWARD WITH
UPSTREAM REGIONAL RADARS REVEALING THE LEADING EDGE OF THE RAINFALL
ACROSS LAKE ONTARIO. PER EXTRAPOLATION...THE WESTERN DACKS WOULD
SEE HIGHER POPS TOWARD OR SHORTLY AFTER THE NOON HOUR THEN SPREAD
INTO EASTERN NY DURING THE MID AND LATE AFTERNOON. THIS TOO IS IN
AGREEMENT WITH THE RATHER AGGRESSIVE HRRR REFLECTIVITY FORECAST.
PER THESE OBSERVATIONS...HAVE LOWERED AFTERNOON HIGHS A COUPLE OF
DEGREES AND MODIFIED PRECIP/POP POTENTIAL PER EXTRAPOLATION TRENDS.
THE MAIN LIFT AND UPPER SUPPORT ARRIVE AFTER SUNSET WHEN THOSE POPS
INCREASE PER THE PREVIOUS FORECAST.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
THE COLD FRONT WILL CROSS THE REGION WITHIN A FEW HOURS EITHER SIDE
OF SUNRISE ON SUNDAY. AHEAD OF THE FRONT HAVE INCREASED POPS TO
BETWEEN 40 AND 50 PERCENT. DRIER AIR RUSHES IN VERY QUICKLY BEHIND
THE FRONT AND THE FLOW BECOME ANTICYCLONIC BY EARLY AFTERNOON. THIS
WILL MINIMIZE THE CONTINUATION OF ANY SHOWERS IN THE COLD ADVECTION
BEHIND THE FRONT AND HAVE FORECAST THE WEATHER TO BECOME PCPN FREE
ACROSS THE ENTIRE REGION FROM LATE MORNING AND BEHIND. AS ANOTHER
SPRAWLING COOL CANADIAN HIGH PRESSURE SYSTEM WILL BUILDS INTO THE
REGION SUNDAY AFTERNOON AND NIGHT AND THEN MOVES OFFSHORE ON
MONDAY...EXPECT CLEAR TO MAINLY CLEAR SKIES WITH COOL TEMPS SUNDAY
AFTN THROUGH MONDAY.
TEMPERATURE WISE...LOWS SATURDAY NIGHT WILL BE IN THE 50S. HIGHS
SUNDAY WILL RANGE FROM THE UPPER 50S OVER THE ADIRONDACKS WHERE THE
COOLER AIR MOVES IN FIRST...TO THE LOW OR MID 70S FROM THE MID
HUDSON VALLEY TO NORTHWEST CONNECTICUT. LOWS SUNDAY NIGHT WILL BE
IN THE 30S TO LOWER 40S AND PATCHY OR AREAS OF FROST HAS BEEN
FORECAST IN COLDER AREAS AND ALSO BEEN HIGHLIGHTED IN THE HWOALY
PRODUCT. HIGHS MONDAY WILL BE IN THE MID 60S TO MID 70S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
ONCE AGAIN PRETTY GOOD AGREEMENT AMONGST THE LONGER RANGE MODELS
ALTHOUGH THE CMC ATTEMPTS TO BRING A TROPICAL SYSTEM NEAR OUR REGION
BY NEXT WEEKEND. SINCE THE OTHER MODELS DO NOT HAVE SUCH A
FEATURE...WE HAVE DISCARDED THAT MODEL.
MONDAY NIGHT...IT LOOKS AS A RATHER STRONG WARM FRONT WILL WORK
ACROSS THE REGION MONDAY NIGHT OR EARLY TUESDAY. THE EUROPEAN MODELS
(ECMWF) CONTINUES TO INDICATE A PRETTY GOOD MCS ASSOCIATED WITH THIS
FEATURE...LESS SO BY THE GFS. THE ECMWF STILL INDICATED A 30-40KT
H850 JET THAT COULD TRANSPORT A SLUG OF ELEVATED CONVECTION INTO THE
ADIRONDACKS. FOR NOW...WE HAVE INTRODUCED 30 POPS ACROSS OUR
NORTHWESTERN ZONES WHERE IT APPEARS THAT GREATEST QPF COULD TAKE
PLACE...SLIGHT POPS ELSEWHERE. OVERNIGHT LOWS LOOK TO BE IN THE 50S
FROM ALBANY SOUTHWARD...40S NORTH.
BY TUESDAY RISING HEIGHTS AND A SOUTHWESTERLY FLOW LOOKS TO USHER IN
SOME MUCH WARMER AND HUMID AIR. DEPENDING ON HOW HOW FAST THE CLOUDS
LIFT OUT WILL ULTIMATELY DETERMINE HOW WARM WE GET. H850
TEMPERATURES LOOK TO JUMP WELL INTO THE TEENS. WE FIGURE THE CLOUDS
WILL BE SOMEWHAT SLOW TO BURN OFF SO WENT ON THE LOWER END OF
MIXING...HIGHS 75 TO 80. WE CARRY ONLY SLIGHT CHANCES OF SHOWERS
THROUGH WEDNESDAY MORNING. TUESDAY NIGHT LOOKS RATHER MUGGY BY
SEPTEMBER STANDARDS WITH LOWS GENERALLY IN THE 60S.
WEDNESDAY LOOKS UNSEASONABLY WARM. H850 TEMPERATURES LOOK TO CREST
NEAR +18C VIA THE 00Z GFS/+20C ON THE ECMWF! WE WENT ON THE HIGH
SIDE OF GUIDANCE WITH HIGHS WELL INTO THE 80S...PUSHING NEAR 90
DEGREES IN THE MID HUDSON VALLEY. DEWPOINTS LOOK TO RISE WELL INTO
THE 60S TO NEAR 70 GIVING THOSE AIR CONDITIONER AT LEAST ONE MORE
WORKOUT FOR THE YEAR.
BY LATE WEDNESDAY...THE AIR LOOKS TO BECOME QUITE UNSTABLE AS THE
FIRST IN A SERIES OF COLD FRONTS (OR PRE-FRONTAL TROUGH) NEARS OUR
REGION. WILL CARRY 30/40 POPS LATE AFTERNOON INTO WEDNESDAY NIGHT.
LOWS WEDNESDAY WILL REMAIN WARM...60S TO NEAR 70.
THURSDAY...IT LOOKS AS NOT ONE BUT TWO FRONTS WILL PASS
THROUGH...LINGERING INTO THE EVENING. WHILE IT WILL LIKELY NOT BE
SHOWERING OR STORMING THE ENTIRE TIME...AT THIS POINT...IT IS HARD
TO TIME WHEN AND IF CONVECTION WOULD OCCUR...BUT THE THREAT
CERTAINLY LOOKS THERE...WITH THE GFS INDICATE SURFACE BASED CAPES
WELL OVER 1000 JOULES. WILL CARRY 30/40 POPS THROUGH THIS PERIOD.
BOTH THE GFS AND ECMWF BOTH INDICATE THE MAJOR COLD FRONT WILL SWEEP
THROUGH THE REGION THURSDAY NIGHT WITH PERHAPS A LINGERING SHOWER OR
TWO. FRIDAY...ANOTHER MUCH COOLER CANADIAN AIRMASS LOOKS TO INVADE.
WILL HAVE SLIGHT POPS ACROSS OUR HIGHER TERRAIN WHERE UPSLOPE AND
LINGERING COLD AIR ADVECTION PROCESSES COULD TRIGGER AN INSTABILITY
SHOWER WHILE VALLEY AREAS LOOK DRY. IT WILL BE QUITE BREEZY. HIGHS
WILL RANGE FROM ABOUT 70 IN THE HUDSON VALLEY...TO ONLY 60S
ELSEWHERE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
KPSF WENT BRIEFLY TO IFR EARLIER THIS MORNING. WHILE KALB DID
NOT...WE HAD IFR CLOUDS AND SOME IFR FOG AT OUR OFFICE THAT WERE
LIKELY BELOW 1000 FEET. FOR NOW WE DECIDED NOT TO INCLUDE THE 200
FOOT BROKEN CEILING AT KALB AND 2SM BR IN A ONE HOUR TEMPO THROUGH
12Z.
ANY AND ALL FOG WILL BURN OFF BY AROUND 13Z....LEAVING US WITH A
VFR DAY. HIGH CLOUDS WILL GENERALLY INCREASE AND SO WILL A SOUTHERLY
BREEZE....TO THE TUNE AROUND 10KTS AT KALB.
ANY AND ALL FOG WILL DISSIPATE BY AROUND 14Z. VFR CONDITIONS WILL
PREVAIL DURING THE DAY SATURDAY WITH A GENERAL INCREASE IN HIGH
CLOUDS AND A SOUTHERLY BREEZE...APPROACHING 10KTS BY MIDDAY.
BY LATE IN THE DAY...A FEW SHOWERS...AHEAD OF THE NEXT COLD FRONT
COULD IMPACT THE TERMINALS PERHAPS A BRIEF REDUCTION IN VISIBILITY
AND LOWERING OF CIGS. FOR NOW...CONTINUED WITH VCSH BY LATE IN THE
AFTERNOON...EXCEPT NOT UNTIL EVENING AT KPOU.
OUTLOOK...
SUNDAY...LOW OPERATIONAL IMPACT. BREEZY.
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF
SHRA...TSRA. TUESDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF
SHRA...TSRA. TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. SLIGHT
CHANCE OF SHRA...TSRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT.
CHANCE OF SHRA...TSRA. WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT.
CHANCE OF SHRA...TSRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER ARE ANTICIPATED OVER THE NEXT SEVERAL DAYS.
RH VALUES WILL DROP TO BETWEEN 35 AND 50 PERCENT THIS AFTERNOON
WITH SOUTH TO SOUTHWEST WINDS AROUND 5 TO 10 MPH. RH VALUES WILL
ONCE AGAIN RETURN TO NEAR 100 PERCENT TONIGHT WITH A GOOD CHANCE OF
RAIN SHOWERS.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH TUESDAY. RIVER LEVELS
WILL CONTINUE TO RECEDE OR HOLD STEADY OVER THE NEXT FEW DAYS.
HIGH PRESSURE WILL MOVE OFF THE EASTERN SEABOARD TODAY. A COLD FRONT
WILL CROSS THE REGION LATE TONIGHT AND EARLY SUNDAY MORNING WITH THE
CHANCE FOR SOME RAIN SHOWERS...FOLLOWED BY BREEZY AND COOLER
CONDITIONS BEHIND IT FOR THE REST OF SUNDAY. AS ANOTHER LARGE HIGH
PRESSURE SYSTEM SETTLES OVER THE REGION...THERE WILL BE DRY WEATHER
THROUGH TUESDAY.
THE QPF OVER THE WEEKEND WILL BE FAIRLY LIGHT. MOST AREAS OUTSIDE
THE ADIRONDACKS WILL ONLY SEE A TENTH OR TWO OF AN INCH AT
MOST...WITH UP TO A THIRD OF AN INCH ACROSS THE ADIRONDACKS. THIS
RAINFALL WILL HAVE LITTLE IMPACT ON AREA RIVERS AND STREAMS.
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...GJM
NEAR TERM...GJM/BGM
SHORT TERM...GJM
LONG TERM...HWJIV
AVIATION...HWJIV
FIRE WEATHER...GJM
HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS MIAMI FL
141 AM EDT SAT SEP 7 2013
.AVIATION...
FOR THE SHORT TERM...THERE ARE SOME THUNDERSTORMS IN THE NEAR
SHORE ATLANTIC WATERS TO THE EAST OF TERMINAL TPBI AND SHOWERS
THAT WILL LIKELY IMPACT THE TERMINAL FOR ABOUT THE NEXT 15 TO 30
MINUTES WITH PERIODS OF SUB-VFR CONDITIONS POSSIBLE AND WITH VERY
BRIEF IFR CONDITIONS POSSIBLE IN THIS TIME FRAME. THE CONVECTION
AFFECTING TERMINAL KPBI IS STARTING TO BREAK UP WITH VCTS
ASSIGNED UNTIL 07Z...WILL AMEND AS NECESSARY. OTHERWISE...WITH
EASTERLY FLOW ACROSS THE ATLANTIC WATERS AND LINGERING BOUNDARIES
FROM CONVECTION EARLIER THIS EVENING A FEW SHOWERS AND/OR ISOLATED
THUNDERSTORMS COULD POP UP BUT MAINLY VFR CONDITIONS EXPECTED FOR
THE REMAINING EAST COAST TERMINALS AND TERMINAL KAPF THE REMAINING
EARLY MORNING HOURS.
60
&&
.PREV DISCUSSION... /ISSUED 847 PM EDT FRI SEP 6 2013/
UPDATE...
ALTHOUGH IT WAS A LATE START FOR THE AFTERNOON SHOWERS AND
STORMS...A LARGE AREA OF HEAVY SHOWERS AND STORMS HAS DEVELOPED
AND BECOME FOCUSED OVER THE GULF COAST AREAS FROM NAPLES TO
EVERGLADE CITY TO CENTRAL COLLIER COUNTY THIS EVENING. THE LATEST
RADAR SCAN ESTIMATED TOTALS RANGING FROM HALF OF AN INCH OVER THE
BULK OF THIS AREA WITH ISOLATED AMOUNTS AS HIGH AS 2.5". THE
LATEST HRRR MODEL REFLECTIVITIES LINE UP WELL WITH THIS ACTIVITY
AND GENERALLY CONTINUES TO SUPPORT THIS COVERAGE WELL INTO THE
LATE EVENING HOURS BEFORE DISSIPATING. IF THIS VERIFIES...AN
ADDITIONAL HALF OF AN INCH TO ONE INCH WITH LOCALLY HIGHER AMOUNTS
WILL BE EXPECTED. THE LATEST FORECAST PACKAGE HAS BEEN UPDATED TO
REFLECT THESE LATEST TRENDS. OTHERWISE...THE PREVIOUS FORECAST
REMAINS ON TRACK THIS EVENING.
PREV DISCUSSION... /ISSUED 736 PM EDT FRI SEP 6 2013/
AVIATION...
VFR PREVAILING AT ALL TERMINALS. VCTS ONLY FOR KAPF THIS EVENING
DUE TO THE ACTIVITY ALREADY NEARBY. EXPECT THIS TO DISSIPATE BY
04Z. VCSH WILL POSSIBLY DEVELOP NEAR ALL EASTERN TERMINALS BY
07/16Z AND WEST COAST SEA BREEZE DEVELOPING BY 07/18Z. VCTS WILL
BE POSSIBLE NEAR KAPF BY THAT TIME ALSO.
PREV DISCUSSION... /ISSUED 230 PM EDT FRI SEP 6 2013/
TYPICAL SUMMER TIME WEATHER THIS WEEKEND BEFORE DRIER
CONDITIONS EARLY NEXT WEEK...
SHORT TERM...
THE EAST AND WEST COAST SEA BREEZES HAVE DEVELOPED EARLY THIS
AFTERNOON WITH THE EAST COAST SEA BREEZE PUSHING ACROSS THE
INTERIOR AREAS. THE EAST COAST SEA BREEZE WILL CONTINUE TO PUSH
WEST ACROSS SOUTH FLORIDA THROUGH THE AFTERNOON HOURS...AS THE
WEST COAST SEA BREEZE REMAINS OVER THE WEST COAST METRO AREAS. AT
THE SAME TIME...A TROUGH OF LOW PRESSURE OVER NORTH FLORIDA WILL
CONTINUE TO MOVE SOUTH INTO CENTRAL FLORIDA. THIS WEATHER PATTERN
WILL ALLOW FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO
DEVELOP OVER THE INTERIOR AND WEST COAST METRO AREAS THIS
AFTERNOON INTO EARLY THIS EVENING...WITH ISOLATED SHOWERS ONLY FOR
THE EAST COAST METRO AREAS. SO WILL KEEP THE 30 TO 50 PERCENT POPS
IN PLACE FOR THE INTERIOR AND WEST COAST METRO AREAS THROUGH EARLY
THIS EVENING...WITH ONLY A 20 PERCENT POPS OVER THE EAST COAST
METRO AREAS OF SOUTH FLORIDA.
THE TROUGH OF LOW PRESSURE WILL REMAIN NEARLY STATIONARY TONIGHT
OVER CENTRAL FLORIDA...BEFORE MOVING SLOWLY SOUTH INTO THE LAKE
OKEECHOBEE AREA ON SATURDAY AND THROUGH SOUTH FLORIDA ON SUNDAY.
THIS WILL KEEP THE STEERING FLOW OVER SOUTH FLORIDA IN A LIGHT
NORTHEAST DIRECTION ALONG WITH THE SEA BREEZE DEVELOPMENT EACH DAY
ALONG BOTH COAST. SO THE SCATTERED POPS WILL REMAIN OVER THE
INTERIOR AND WEST COAST METRO AREAS WITH ISOLATED POPS OVER THE
EAST COAST METRO AREAS EACH DAY THIS WEEKEND. THE THREAT OF
THUNDER WILL ALSO BE FOCUS MAINLY OVER THE INTERIOR AND WEST COAST
METRO AREAS EACH DAY THIS WEEKEND..BUT THE EAST COAST METRO AREAS
COULD SEE A THUNDERSTORM OR TWO.
THE 500 MB TEMP WILL ALSO REMAIN VERY COLD FOR THIS TIME OF YEAR
IN THE -8C TO -9C OVER SOUTH FLORIDA. THIS WILL ALLOW FOR SOME OF
THE STORMS EACH DAY THIS WEEKEND TO BECOME STRONG OVER SOUTH
FLORIDA ESPECIALLY WHERE THE SEA BREEZES COLLIDE EACH DAY. THE
PRIMARY IMPACTS FROM THE STRONG STORMS WILL MORE LIKELY BE
LIGHTNING STRIKES, GUSTY WINDS, AND HAIL. SO WILL MENTION THIS IN
THE AFTERNOON HWO PACKAGE.
LONG TERM...
THE TROUGH OF LOW PRESSURE WILL MOVE INTO THE FLORIDA KEYS EARLY
NEXT WEEK BEFORE MOVING BACK UP INTO SOUTH FLORIDA FOR THE MIDDLE
OF NEXT WEEK...AS AN UPPER LEVEL LOW DEVELOPS OVER THE WESTERN
ATLANTIC WATERS. THIS WILL ALLOW FOR SOME DRIER AIR TO WORK INTO
SOUTH FLORIDA FROM THE NORTH EARLY NEXT WEEK...BEFORE MOISTURE
RETURNS TO THE AREA FOR MIDDLE OF NEXT WEEK. THEREFORE...THE POPS
FOR EARLY NEXT WEEK HAVE BEEN LOWER TO SLIGHT CHANCE OVER MOST
OF SOUTH FLORIDA EXCEPT LOW END CHANCE OVER THE WESTERN AREAS.
FOR MIDDLE OF NEXT WEEK...THE POPS WILL REMAIN IN THE CHANCE CAT
OVER SOUTH FLORIDA.
AVIATION...
A WEAK TROUGH IS TRYING TO MAKES ITS WAY INTO SOUTH FLORIDA THIS
AFTERNOON. THIS SHOULD ACT TO ENHANCE CONVECTION IN THE WESTERN
HALF OF THE AREA. THE SEA BREEZE WILL KEEP THE EAST COAST CLEAR OF
MOST CONVECTION, ALTHOUGH AN ISOLATED SHOWERS MAY STILL TRY TO
FORM. GIVEN THIS, HAVE KEPT ANY SHRA/TSRA OUT OF THE EASTERN SITES
THIS AFTERNOON. FOR KAPF, HAVE DELAYED VCTS FOR A FEW HOURS AS THE
MODELS INDICATE IT WILL BE MORE TOWARDS THE MID AFTERNOON BEFORE
CONVECTION AFFECTS NAPLES. HOWEVER, THIS COULD BE OFF A LITTLE, SO
VCTS MAY NEED TO ADDED, OR EVEN DELAYED SOME, BASED ON DEVELOPMENT.
WINDS WILL BE GENERALLY EASTERLY THIS AFTERNOON, WITH THE
EXCEPTION OF KAPF, WHERE THE GULF BREEZE IS EXPECTED TO JUST MAKE
IT PAST THE AIRPORT. TONIGHT, WINDS WILL LIGHTEN AND GO VARIABLE
IN MANY LOCATIONS. THEY WILL ONCE AGAIN BECOME EASTERLY TOMORROW
BETWEEN 5 AND 10 KTS.
MARINE...
THE WINDS WILL REMAIN FROM THE EAST NORTHEAST AT 10 KNOTS OR LESS
THIS WEEKEND INTO EARLY NEXT WEEK OVER ALL OF SOUTH FLORIDA
WATERS. THIS WILL KEEP THE SEAS IN BOTH THE ATLANTIC AND GULF
WATERS AT 2 FEET OR LESS. SO BOATING CONDITIONS WILL BE GOOD OVER
ALL OF SOUTH FLORIDA WATERS OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 89 77 88 77 / 40 20 20 10
FORT LAUDERDALE 89 79 89 79 / 40 20 20 10
MIAMI 90 78 89 78 / 50 20 20 10
NAPLES 91 74 91 74 / 50 30 30 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...23/SK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
142 AM EDT SAT SEP 7 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL CONTINUE TO PUSH SOUTH OF THE AREA THIS
EVENING WITH HIGH PRESSURE BUILDING FROM THE NORTH AND EXTENDING
ACROSS THE AREA THROUGH THIS WEEKEND. A BACKDOOR COLD FRONT WILL
APPROACH FROM THE NORTH SUNDAY AND BECOME STATIONARY NEAR OR JUST
NORTH OF THE AREA MONDAY BEFORE DISSIPATING. HIGH PRESSURE WILL
THEN PREVAIL THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A HIGHLY AMPLIFIED AND DEEP LAYERED ANTICYCLONE WILL REMAIN
POSITIONED IN THE CENTRAL PLAINS/ROCKIES...AS A LOW AMPLITUDE
SHORT WAVE DROPS SE THROUGH THE MEAN LONG WAVE TROUGH ALONG THE
EASTERN SEABOARD. AT THE SURFACE AN ELONGATED REGION OF HIGH
PRESSURE TO THE NORTH WILL CONTINUE TO BUILD INTO THE
REGION...BRINGING WITH IT CONSIDERABLE DRY AIR ABOVE THE FIRST
MILE OR SO OF THE TROPOSPHERE.
EARLY MORNING RADAR IMAGERY DEPICTS CONVECTION SHIFTING SOUTHWARD
JUST OFF THE SOUTH CAROLINA COAST DUE TO JUST ENOUGH LOW LEVEL
MOISTURE ALONG WITH SOME ISENTROPIC LIFT ON THE 295K AND 300K
SURFACES. WHILE TRAJECTORIES GENERALLY SUGGEST THAT THEY WILL
REMAIN OVER THE ATLANTIC WHERE WHAT LITTLE LOW LEVEL CONVERGENCE
AND LIFT WILL BE FOUND...SOME OF THE HIGHER RESOLUTION MESOSCALE
MODELS SUCH AS THE HRRR SHOW SOME JUST BRUSHING COASTAL AREAS. AS A
RESULT...HAVE ADDED MENTION OF A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS FOR IMMEDIATE COASTAL AREAS THROUGH DAYBREAK.
OTHER THAN SOME STRATOCUMULUS OVER COASTAL AREAS...LITTLE CLOUD
COVER AND MOSTLY CALM WINDS INLAND WILL CONTINUE TO PROMOTE DECENT
RADIATIONAL COOLING. BUT GIVEN THAT GEOSTROPHIC WINDS DO HOLD
AROUND 10-15 KT WE WON/T GO TOO LOW...WITH MINIMUM TEMPS GENERALLY
CLOSE TO SEASONAL LEVELS. 66-70 WEILL BE COMMON INLAND FROM
US-17...WITH LOWER AND MIDDLE 70S CLOSER TO THE COAST WHERE A
LIGHT NE AND EAST WIND WILL EXIST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
SATURDAY THROUGH MONDAY...PRONOUNCED LONGWAVE TROUGHING WILL
DOMINATE MUCH OF THE EASTERN U.S. THIS WEEKEND BEFORE LIFTING OUT
EARLY NEXT WEEK. AT THE SURFACE...DRY SURFACE HIGH PRESSURE WILL
EXTEND SOUTH ACROSS THE AREA. FORECAST SOUNDINGS INDICATE ONLY
SHALLOW LOW-LEVEL MOISTURE WILL BE PRESENT SATURDAY...WITH THE DEPTH
OF THE BEST LOW-LEVEL MOISTURE INCREASING SUNDAY AND MONDAY AS THE
LOW-LEVEL FLOW BECOMES MORE ONSHORE. THIS WILL RESULT IN VERY SMALL
PROBABILITIES FOR MEASURABLE RAINFALL THROUGH EARLY NEXT WEEK.
SATURDAY LOOKS THE DRIEST WITH NO ACTIVITY...BUT ISOLATED
SHOWERS/TSTMS WILL BE POSSIBLE ACROSS MAINLY SOUTH COASTAL SOUTH
CAROLINA WITH THE SEA BREEZE SUNDAY. THE BACKDOOR FRONT WILL DROP
SOUTH AND BECOME STATIONARY NEAR OR JUST NORTH OF THE AREA MONDAY
MORNING...THUS ITS PROXIMITY COUPLED WITH THE AFTERNOON SEA BREEZE
NECESSITIES KEEPING SLIGHT CHANCE POPS IN PLACE FOR ALL AREAS
MONDAY...ALTHOUGH THE MAJORITY OF THE MODELS KEEP CONDITIONS DRY.
THE ONLY EXCEPTION IS THE GFS WHICH SHOWS QUITE A BIT OF ACTIVITY
FORMING ACROSS MAINLY SOUTHEAST SOUTH CAROLINA. THIS SOLUTION IS
DISCOUNTED FOR NOW.
TEMPERATURES WILL BE SEASONABLE THROUGH THE PERIOD WITH HIGHS IN THE
UPPER 80S TO LOWER 90S WITH LOWS UPPER 60S TO MID 70S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
GOOD MODEL AGREEMENT THIS PERIOD WITH HIGH PRESSURE PREVAILING INTO
THURSDAY BEFORE ANOTHER WEAK COLD FRONT PUSHING INTO THE AREA
FRIDAY. FAIRLY TYPICAL SUMMERTIME PATTERN EXPECTED WITH MOSTLY
ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS EACH AFTERNOON THROUGH
THURSDAY. RAIN CHANCES SHOULD INCREASE A BIT FRIDAY WITH THE FRONT
IN THE VICINITY. TEMPERATURES SHOULD BE NEAR OR SLIGHTLY ABOVE
NORMAL THROUGH THE PERIOD.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KCHS AND KSAV THROUGH
06Z SUNDAY.
EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS WITH A GREATER
THAN 30 PERCENT CONFIDENCE AT THIS TIME.
&&
.MARINE...
TONIGHT...HIGH PRESSURE WILL CONTINUE TO NUDGE FURTHER SOUTH AND
SW. THERE IS ENOUGH OF A PRESSURE GRADIENT TO KEEP EAST AND NE
WINDS UP NEAR 10 OR 15 KT...BEFORE THEY BACK MORE NORTHERLY WITH
LAND BREEZE INFLUENCES LATE. SEAS WON/T CHANGE MUCH,,,HOLDING
AROUND 2 OR 3 FT...A MIX OF SMALL SWELLS AND WIND DRIVEN ENERGY.
SATURDAY THROUGH MONDAY...A STEADY NORTHEAST FLOW WILL DOMINATE
SATURDAY WITH WINDS AROUND 10 KT...POSSIBLY A BIT HIGHER ALONG THE
LAND/SEA INTERACT WITH THE SEA BREEZE. WINDS ARE EXPECTED TO BECOME
MORE ONSHORE SUNDAY AND MONDAY AS THE FLOW-LEVEL FLOW RESPONDS TO
HIGH PRESSURE SHIFTING OFFSHORE. BOTH WINDS AND SEAS LOOK TO REMAIN
WELL BELOW SMALL CRAFT ADVISORY CRITERIA.
TUESDAY AND WEDNESDAY...NO SIGNIFICANT CONCERNS THIS PERIOD. WINDS
MOSTLY 15 KT OR LESS WITH SEAS GENERALLY 3 FT OR LESS.
RIP CURRENTS...WW4 OUTPUT FORECASTS AN UNDERLYING 2 FOOT SWELL
DEVELOPING TONIGHT AND PERSISTING INTO SATURDAY WITH PERIODS
INCREASING TO ABOUT 9 SECONDS. MODEST NORTHEAST WINDS COUPLED WITH
THIS INCREASING SWELL AND INCREASING LUNAR INFLUENCES WILL PRODUCE A
BORDERLINE MODERATE RISK FOR THE GEORGIA BEACHES SATURDAY. OPTED TO
CAP THE RISK AT A HIGH-END LOW RISK FOR NOW GIVEN ITS AFTER THE MAIN
BEACH SEASON...BUT THIS COULD EASILY BE UPPED TO A MODERATE RISK
WITH LATER FORECASTS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...JAQ
SHORT TERM...ST
LONG TERM...RJB
AVIATION...JAQ/ST
MARINE...
AREA FORECAST DISCUSSION
NWS POCATELLO ID
906 AM MDT SAT SEP 7 2013
.UPDATE...STRONG MOISTURE GRADIENT LAYING ACROSS EAST IDAHO TODAY
AS UPPER LOW CONTINUES TO DRIFT EAST ALONG THE PACNW/CANADIAN
BORDER. DEEPEST MOISTURE IN PLACE OVER THE EASTERN HALF OF THE
FORECAST AREA MAINLY SNAKE PLAIN AND HIGHLANDS SOUTH/EAST. CENTRAL
MOUNTAINS MUCH DRIER BUT CLOSER TO BEST DYNAMICS ASSOCIATED WITH
UPPER LOW. HRRR THIS MORNING PAINTING WIDE SWATH OF MOISTURE
MOVING THROUGH THE SOUTH/EAST HIGHLANDS LATE THIS MORNING INTO
EARLY THIS AFTERNOON. NAM/LOCAL WRF DEVELOPS BETTER SWATH OF
CONVECTION LATER THIS AFTERNOON. CLOUD COVER EARLY THIS MORNING
MAY ALSO HAVE A SMALL IMPACT ON INSTABILITY. HAVE MADE A FEW
TWEAKS TO SKY/POP/WX GRIDS FOR TODAY...HOLDING ON TO HIGH CHANCE
POPS IN THE DEEPEST MOISTURE BUT RETAINING ISOLATED POPS OVER
PORTIONS OF THE CENTRAL MOUNTAINS. DMH
&&
.PREV DISCUSSION... /ISSUED 319 AM MDT SAT SEP 7 2013/
SHORT TERM...TODAY THROUGH MONDAY.
UPPER LOW IN WASHINGTON STATE WILL CONTINUE TO PUSH VERY SLOWLY
EAST THROUGH MONDAY. MONSOONAL MOISTURE CONTINUES TO BE OVER THE
REGION ON THE SOUTHWESTERLY FLOW ALOFT AND EXPECT CONTINUED
ISOLATED TO SCATTERED THUNDERSTORMS TODAY WITH THE BEST ACTIVITY
AGAIN IN THE EASTERN AREAS. UPPER TROF FINALLY MOVES THROUGH
SUNDAY AND ENOUGH DYNAMICS AND INSTABILITY TO CONTINUE WITH THE
THREAT FOR THUNDERSTORMS BUT NOT AS WIDESPREAD AS TODAY. FLOW
ALOFT TURNS NORTHWESTERLY MONDAY AND EXPECT DRY CONDITIONS ACROSS
THE WHOLE REGION FINALLY. TEMPERATURES MONDAY SHOULD ALSO BE NEAR
SEASONAL NORMALS AFTER THE EXTENDED PERIOD OF WELL ABOVE NORMAL
CONDITIONS. EXPECT SOME BREEZY CONDITIONS SUNDAY WITH THE PASSAGE
OF THE UPPER TROF AND SURFACE COLD FRONT.
GK
LONG TERM...TUESDAY THROUGH SATURDAY.
UPPER RIDGE BUILDS IN TUESDAY AND EXPECT DRY CONDITIONS TUESDAY
AND WEDNESDAY. FLOW AGAIN TURNS SOUTHERLY ALLOWING MOISTURE BACK
INTO THE REGION AND HAVE A CHANCE OF SHOWERS AND THUNDERSTORMS
THURSDAY THROUGH SATURDAY.
GK
AVIATION...THE LATEST SATELLITE IMAGERY WAS SHOWING A LOW PRESSURE
SYSTEM LIFTING NORTH INTO SRN BRITISH COLUMBIA AS SUB-TROPICAL
MOISTURE CONTINUED TO ARC NORTH ACROSS SE IDAHO AND DRIER CONDITIONS
OVERSPREAD THE SW. MODEL SOLUTIONS SHOW THE UPPER LOW SHIFTING EAST
ALONG THE CANADIAN BORDER TODAY AND SUNDAY EFFECTIVELY SHUNTING THE
SUB-TROPICAL FLOW FURTHER EAST INTO WYOMING SUNDAY. MAY STILL HAVE
TO CONTEND WITH VCTS/TSRA REMARKS IN THE TERMINALS TODAY AND TO A
LESSER EXTENT SUNDAY AS THE SUB-TROPICAL MOISTURE IS PUSHED FURTHER
EAST...OTHERWISE VFR CONDITIONS SHOULD PREVAIL. HUSTON
FIRE WEATHER...A LOW PRESSURE SYSTEM POSITIONED ALONG THE
WASHINGTON/BRITISH COLUMBIA BORDER EARLY THIS MORNING WILL BEGIN TO
MIGRATE EAST TODAY AND SUNDAY. SUB-TROPICAL MOISTURE STREAMING NORTH
ACROSS THE GREAT BASIN WILL GET SHUNTED FURTHER EAST INTO WYOMING
SUNDAY AND COLORADO BY MONDAY AS A FAIRLY DRY NW FLOW OVERSPREADS
IDAHO IN THE WAKE OF THE EXITING LOW. WIND GUSTS WILL NOSE UP TOWARD
WARNING LEVELS SUNDAY AFTERNOON WHILE MINIMUM HUMIDITY LEVELS FALL
INTO THE UPPER TEENS ACROSS THE CNTRL MOUNTAINS AND ARCO DESERT
REGIONS. FUELS STILL FAIRLY MOIST DUE TO RECENT MONSOONAL ACTIVITY
THUS NO HIGHLIGHTS ARE WARRANTED AT THIS TIME. A RIDGE OF HIGH
PRESSURE AND WARMER TEMPERATURES BUILD ACROSS THE REGION THROUGH
MID-WEEK AS A SUB-TROPICAL DISTURBANCE LIFTS NORTH THROUGH
MEXICO/ARIZONA. THE ADVANCING SUB-TROPICAL MOISTURE WILL LIKELY LIFT
INTO SRN IDAHO THURSDAY/FRIDAY FOR YET ANOTHER ROUND OF HEAVY
SHOWERS AND THUNDERSTORMS. HUSTON
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
959 PM CDT SUN SEP 8 2013
.DISCUSSION...
251 PM CDT
MAIN FORECAST CONCERNS WILL BE TEMPERATURES MONDAY AND TUESDAY AS
HEAT RETURNS TO THE AREA...AS WELL AS PERIODIC CHANCES FOR
THUNDERSTORMS TONIGHT THROUGH EARLY MONDAY...AND AGAIN TUESDAY NIGHT
THROUGH WEDNESDAY NIGHT.
THIS AFTERNOON...A COLD FRONT STRETCHES FROM SOUTH DAKOTA SOUTHEAST
INTO SOUTHERN ILLINOIS. DEWPOINTS POOLING INTO THE LOW 70S ALONG THE
FRONTAL BOUNDARY HAVE LED TO MLCAPE AXIS OF 2000-2500 J/KG JUST
SOUTH OF THE CWA...WITH JUST OVER 1000 J/KG INTO THE FAR SOUTHERN
CWA PER SPC MESOANALYSIS. WEAK SURFACE CONVERGENCE ACROSS CENTRAL
ILLINOIS...WEAKLY ENHANCED BY DIFFERENTIAL HEATING BETWEEN THE
THICKER CIRRUS SHIELD TO OUR SOUTH HAS LED TO A FEW SHOWERS AND
THUNDERSTORMS ACROSS THE SOUTHERN CWA. OVER THE NEXT FEW
HOURS...EXPECT THE WIDELY SCATTERED ACTIVITY TO CONTINUE...BUT
SHOULD FADE WITH LOSS OF HEATING THIS EVENING...PROVIDING AT LEAST A
BRIEF DRY WINDOW ACROSS THE CWA.
TONIGHT THROUGH TOMORROW...
CLOSED UPPER LOW CURRENTLY OVER MONTANA IS PROGGED TO MOVE EAST THIS
EVENING AND TONIGHT...WHILE SURFACE LOW OVER THE PLAINS LIFTS
NORTHEAST...DEEPENING SLIGHTLY AS IT MOVES OVER MINNESOTA BY
TOMORROW AFTERNOON. THE FRONTAL BOUNDARY TO OUR SOUTH WILL BEGIN TO
LIFT NORTH ACROSS THE AREA TONIGHT WITH A BAND OF MID LEVEL
ISENTROPIC ASCENT SLOWLY TRANSITIONING WEST TO EAST ACROSS THE
CWA FROM LATE THIS EVENING THROUGH MONDAY MORNING...BRINGING AT
LEAST A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGH THE
OVERNIGHT HOURS. NAM SUGGESTS A SLOWER PROGRESSION OF THIS FEATURE
WITH ASCENT STILL OCCURRING IN THE EASTERN PORTIONS OF THE CWA EARLY
MONDAY AFTERNOON...AT WHICH TIME MODERATE INSTABILITY WILL HAVE
DEVELOPED...WEAKLY CAPPED ON THE LEADING EDGE OF THE EML WHICH WILL
BE ADVECTING EAST INTO THE AREA THROUGH THE DAY. IF THIS PANS
OUT...CONCERNED THAT WE MAY SEE SOME INTENSIFICATION OF ANY SHOWERS
THAT MAY DEVELOP OVERNIGHT AS THEY BECOME ROOTED IN THE BOUNDARY
LAYER LATE TOMORROW MORNING OR EARLY AFTERNOON OVER FAR EAST CENTRAL
ILLINOIS OR NORTHWEST INDIANA. OVERALL CONFIDENCE IN PRECIP IS PRETTY
LOW THOUGH...WITH LACK OF ANY SIGNIFICANT UPPER LEVEL SUPPORT
THROUGH THE PERIOD. IF ANYTHING DID DEVELOP COVERAGE MAY END OF
STAYING PRETTY LOW.
ATTENTION TURNS TO TEMPERATURES TOMORROW AFTERNOON. STOUT CAPPING
INVERSION ADVECTS IN FROM THE WEST AND MODEST DRYING SHOULD ALLOW
SKIES TO CLEAR BEHIND ANY MID LEVEL CLOUDINESS ASSOCIATED WITH THE
WARM FRONT EARLY IN THE DAY. BETWEEN 18Z AND 00Z...H92 TEMPS ARE
EXPECTED TO WARM FROM AROUND 23C TO NEAR 27C...MOVING OFF THE CHARTS
SO TO SPEAK WITH RESPECT TO LOCAL UPPER AIR CLIMATOLOGY. QUITE A BIT
OF VARIANCE IN MODEL PROG SURFACE TEMPERATURES TOMORROW. GFS AND GEM
SHOW LOW TO MID 80S ACROSS THE CWA...WHILE THE NAM AND ECMWF
INDICATE TEMPERATURES SOARING INTO 90S. GIVEN THE EXPECTED WARM
ADVECTION AND CLEARING SKIES...SEE LITTLE SUPPORT FOR THE COOLER
MODELS...AND ENDED UP BUMPING TEMPERATURES A COUPLE DEGREES MONDAY
TOWARDS A BLEND OF THE ECMWF/ECMWFBC...CALLING FOR LOW 90S ACROSS
THE CWA...AND 91/93 AT ORD/RFD RESPECTIVELY.
TUESDAY...
CONTINUE TO LOOK AT NEAR RECORD HIGH TEMPERATURES ON TUESDAY AS WE
SIT SQUARELY UNDER THE THERMAL RIDGE. MODELS IN DECENT AGREEMENT
SHOWING H85 TEMPS BETWEEN 21-22C...AND H92 TEMPS BETWEEN 27-28C...
AGAIN OFF THE CHARTS WITH RESPECT TO LOCAL CLIMATOLOGY. DEEP MIXING
DURING THE DAY SHOULD HELP TO MIX THE DEWPOINTS TOWARDS THE UPPER
50S...WHICH WILL HELP TEMPERATURES QUICKLY RESPOND. WITH GREATER
CONFIDENCE THAT WE SHOULD SEE PLENTY OF SUNSHINE...FULLY EXPECT TO
BE FLIRTING WITH IF NOT EXCEEDING RECORD HIGHS ON TUESDAY. SEE
CLIMATE SECTION FOR INFORMATION ON RECORD TEMPS. BLENDED WITH
ECMWF/GEMNH GUIDANCE WHICH TENDS TO VERIFY WELL UNDER A STRONG
THERMAL RIDGE...BUMPING UP TEMPS ABOUT A DEGREE OR SO FROM THE
PREVIOUS FORECAST...AND CALLING FOR TEMPS INTO THE MID 90S ACROSS
THE CWA.
WEDNESDAY...
A COLD FRONT IS EXPECTED TO SAG SOUTH ACROSS THE CWA ON WEDNESDAY.
EXPECT A SPREAD IN HIGH TEMPERATURES NORTH TO SOUTH ACROSS THE CWA
DEPENDING ON FRONTAL TIMING...WITH LOW 80S IN THE NORTH TO LOW 90S
IN THE SOUTH. MODERATE INSTABILITY IS EXPECTED TO DEVELOP JUST AHEAD
OF THE FRONT...WITH THUNDERSTORMS EXPECTED PARTICULARLY DURING THE
AFTERNOON HOURS AIDED BY SURFACE HEATING. OVERALL DYNAMICS WITH THIS
SYSTEM APPEAR PRETTY WEAK...WITH WEAK CONVERGENCE ALONG THE
FRONT...AND THE MAIN UPPER WAVE EXPECTED TO PASS WELL TO THE NORTH.
THIS SHOULD LEAD TO LOWER COVERAGE OF THUNDERSTORMS ALONG THE FRONT.
THURSDAY THROUGH SUNDAY...
STRONG CANADIAN HIGH WILL BUILD SOUTH ACROSS THE AREA PROVIDING A
DRIER PERIOD AS WELL AS COOLER WEATHER. BOTH THE GFS AND ECMWF
ADVERTISE H85 TEMPS FALLING TO AROUND 3C FRIDAY AFTERNOON.
FRIDAY...WHICH SHOULD BE THE COOLEST DAY THE UPCOMING WEEK...WE ARE
LOOKING AT HIGHS ONLY THE THE UPPER 60S NORTH OF I-80...AND AROUND
70 SOUTH. TEMPERATURES SHOULD START TO MODERATE NEXT WEEKEND AS THE
HIGH SHIFTS EAST AND RETURN FLOW SPREADS OVER THE AREA.
DEUBELBEISS
&&
.CLIMATE...
THERE IS A CHANCE THAT RECORD WARM LOWS WILL OCCUR TUESDAY
SEPTEMBER 10TH...WITH A SLIGHT CHANCE OF RECORD HIGH TEMPERATURES.
CHICAGO:
RECORD HIGH: 95 (1983)
RECORD WARM LOW: 75 (1912)
ROCKFORD:
RECORD HIGH: 96 (1931)
RECORD WARM LOW: 70 (2000)
TRS/RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* SOME POTENTIAL FOR REDEVELOPMENT OF MVFR CIGS OVERNIGHT AND
EARLY MONDAY MORNING...AND POSSIBLY SOME MVFR HAZE.
* SOUTHEAST WINDS OVERNIGHT BECOMING BREEZY FROM THE SOUTH-
SOUTHWEST MONDAY. GUSTS NEAR 20 KT POSSIBLE IN THE AFTERNOON.
RATZER
//DISCUSSION...UPDATED 00Z...
MAIN FORECAST CONCERNS ARE WITH THE POTENTIAL FOR CIG/VIS TO
DETERIORATE BACK INTO MVFR OR EVEN IFR RANGE OVERNIGHT INTO EARLY
MONDAY MORNING.
SFC HIGH PRESSURE WAS MOVING SOUTHEAST ACROSS THE CENTRAL/EASTERN
GREAT LAKES THIS EVENING...WHILE COLD FRONT WHICH PUSHED ACROSS
THE AREA LAST NIGHT STRETCHED FROM THE MID-MISSOURI VALLEY TO
CENTRAL ILLINOIS. THIS FRONT WILL LIFT BACK TO THE NORTHEAST
ACROSS THE TERMINALS MONDAY MORNING...IN RESPONSE TO AN AREA OF
LOW PRESSURE OVER THE PLAINS WHICH WILL LIFT ACROSS THE UPPER
MISSISSIPPI VALLEY. WHILE LOWER CLOUDS HAVE SCATTERED FOR THE MOST
PART EARLY THIS EVENING...DIURNAL COOLING OF THE MOIST BOUNDARY
LAYER AND CONVERGENCE IN THE VICINITY OF THE LOW LEVEL FRONTAL
ZONE MAY RESULT IN RE-DEVELOPMENT OF MVFR OR EVEN IFR CIGS ALONG
WITH MVFR HAZE OVERNIGHT WHICH COULD LINGER UNTIL THE WARM FRONT
MOVES NORTHEAST OF THE TERMINALS MONDAY MORNING. COMPLICATING THIS
SCENARIO IS THE PROSPECT FOR HIGHER LEVEL CLOUDINESS TO INCREASE
ACROSS OVER/NEAR THE AREA AS THE LOW LEVEL JET BECOMES
SOUTHWESTERLY ABOVE THE FRONTAL ZONE OVERNIGHT. THIS COMPLEXITY
LOWERS CONFIDENCE IN THE DETAILS OF THE CEILING FORECAST THROUGH
MONDAY MORNING. IN ADDITION...MODEL RUNS INDICATE THAT SCATTERED
SHRA/TSRA MAY DEVELOP ACROSS WISCONSIN AS THE LOW LEVEL JET
DEVELOPS TONIGHT...WITH SOME POTENTIAL FOR A FEW SHRA/ISOLATED
TSRA INTO NORTHERN IL/LAKE MICHIGAN. CONFIDENCE IN THIS OCCURRENCE
TOO LOW TO INCLUDE AT TAFS AT THIS TIME...WITH BULK OF SHRA/TSRA
LIKELY TO BE FARTHER NORTH.
AS FOR WINDS...EAST WINDS WILL GRADUALLY DIMINISH AND BECOME
SOUTHEAST THIS EVENING AS THE SURFACE HIGH CONTINUES OFF TO THE
EAST. WINDS WILL THEN VEER TO THE SOUTH-SOUTHWEST WITH THE PASSAGE
OF THE WARM FRONT MID-LATE MONDAY MORNING. WINDS 190-210 DEGREES
SHOULD BECOME SOMEWHAT GUSTY BY MID-LATE AFTERNOON AS BOUNDARY
LAYER MIXING DEEPENS.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* MEDIUM-LOW CONFIDENCE IN CIG/VIS FORECAST OVERNIGHT/EARLY
MONDAY.
* HIGH CONFIDENCE IN VFR CONDITIONS PREVAILING MID/LATE MONDAY
MORNING ONWARD.
* HIGH CONFIDENCE IN WIND TRENDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...VFR. CHANCE OF TSRA WITH MVFR POSSIBLE TUES NGT.
WEDNESDAY...CHANCE TSRA. MVFR POSSIBLE.
THURSDAY THROUGH SATURDAY...VFR,
RATZER
&&
.MARINE...
139 PM CDT
THE WINDS ACROSS THE LAKE HAVE VEERED EASTWARD IN RESPONSE TO THE
SURFACE HIGH BUILDING EASTWARD ACROSS FAR SOUTHERN ONTARIO AND THE
UPPER GREAT LAKES. THIS SURFACE HIGH WILL CONTINUE
EAST-SOUTHEASTWARD ACROSS THE NORTHERN ATLANTIC COAST BY EARLY
MONDAY. THIS WILL ALLOW THE WINDS TO CONTINUE VEERING TO THE
SOUTHEAST TONIGHT...AND THEN SOUTHERLY FOR MONDAY. WIND SPEEDS WILL
LIKELY REMAIN ELEVATED UP TO 15 TO 25 KT INTO MONDAY. HOWEVER...IT
APPEARS THAT SOME 30 KT SOUTHERLY WINDS WILL DEVELOP LATE MONDAY
AND MONDAY NIGHT...ESPECIALLY OVER THE NORTHERN HALF OF THE LAKE AS
A POTENT AREA OF LOW PRESSURE TRACKS ACROSS LAKE SUPERIOR.
THIS LOW LOOKS TO DROP A WEAK COLD FRONT ACROSS THE LAKE BY TUESDAY
NIGHT. HOWEVER...THE WIND SPEEDS LOOK TO ABATE DURING THIS TIME. A
SECOND AREA OF LOW PRESSURE IS FORECAST TO SHIFT ACROSS ONTARIO
AROUND MID WEEK...AND THIS LOW LOOKS TO DROP A MUCH STRONGER COLD
FRONT DOWN THE LAKE INTO THURSDAY. A PERIOD OF STRONG NORTHERLY
WINDS IS POSSIBLE BEHIND THIS FRONT LATER IN THE WEEK AS A MUCH
COLDER AIR MASS SPILLS OVER THE LAKE AHEAD OF A POTENT SURFACE HIGH.
FOR THE NEAR SHORE WATERS...I PLAN ON KEEPING THE SMALL CRAFT
ADVISORY AS IS THROUGH THIS EVENING FOR 4 TO 7 FOOT WAVES ALONG THE
ILLINOIS NEAR SHORES. THE WAVES WILL LIKELY BE SLOW TO SUBSIDE
TONIGHT ALONG THE NORTHERN ILLINOIS NEAR SHORES...BUT IT APPEARS
THAT THEY WILL SUBSIDE INTO THE 2 TO 5 FOOT RANGE...THUS AN
EXTENSION TO THE SMALL CRAFT ADVISORY IS NOT ANTICIPATED AT THIS
TIME.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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[top]
Area Forecast Discussion
National Weather Service Lincoln IL
846 PM CDT Sun Sep 8 2013
.DISCUSSION...
ISSUED 842 PM CDT Sun Sep 8 2013
Latest surface analysis indicates the "cool" front that pushed
through our area early this morning has started back north as a
warm front this evening. Most winds, except for our far north and
east, have turned more into a southeast to south direction
suggesting the boundary is lifting thru our forecast area. Question
now is precip chances with the boundary already shifting into our
northern areas this evening. 00z 850 mb map indicates the warm front
situated from from eastern Iowa thru extreme west central IL. Some
weak speed convergence noted over northeast Mo and west central IL
early this evening but the stronger core of winds was well to our
west. Last several runs of the HRRR model showing some showers trying
to develop over extreme southwest IL after midnight and then tracking
south. Evening 700 mb map indicating another surge of very warm
air...+12C just to our west, which should advect into our area on
Monday as upper level heights build over the region with some very
hot temperatures for the first half of the work week.
Overall, zone forecast is in good shape. Only making some minor
adjustments to the overnight hours, specifically for temperatures
and cloud cover, along with some overnight adjustments to wording
in the ZFP. Should have the update out by 900 pm.
Smith
&&
.AVIATION...
ISSUED 610 PM CDT Sun Sep 8 2013
Possible MVFR vsbys in fog between 09z-13z, otherwise VFR conditions
are expected through this period. Weak frontal boundary stretched
across the area late this afternoon with very light east winds to
its north, and a southeast to south wind to the south of the frontal
bounday. Front should edge slowly northeast late tonight and be north
of our area tomorrow. With the residual low level moisture in place
and a mainly clear sky overnight, some patchy ground fog will be
possible towards dawn. What fog we do see early in the morning should
lift by 14z with only a scattering of cumulus expected after that.
With the front north of our area tomorrow, a south to southwest wind
will prevail at 10 to 15 kts.
Smith
&&
.PREV DISCUSSION...
ISSUED 250 PM CDT Sun Sep 8 2013
SHORT TERM...Today through Thursday
A frontal boundary over central IN/IL to near the IA/MO border
will linger isolated showers and thunderstorms into this evening.
MCS that brought heavy rains to westcentral IL overnight/early
this morning has dissipate as it moved sse into southern IL by
afternoon. Not much lift or convergence along frontal boundary but
heating of tropical airmass with dewpoints in the upper 60s to
near 70F giving unstable capes peaking from 1.5-3K j/kg late this
afternoon. Some stratus and fog more likely over northern IL
tonight as front lifts northward toward northern IL overnight.
Areas from I-74 north may see some of this stratus and fog but
more likely further north. Lows overnight close to dewpoints in
the upper 60s, to near 70F sw areas.
Hot conditions still on tap for Monday and Tuesday with highs in
the low to mid 90s Monday and into the 90s Tuesday with some upper
90s sw areas. Will likely be shy of record highs near 100F on
Monday but may be close to record highs on Tuesday which are 97F
at Peoria and Lincoln and 98F in Springfield. Kept dry conditions
from Monday through Tuesday as 592 dm 500 mb subtropical ridge
over the central plains shifts ese into the mid ms and tn valleys.
Models continue to drive a cold front se toward nw IL late
Wednesday and brings a chance of showers and thunderstorms mainly
to the IL river valley. Cold front to push se through central and
se IL Wed night and bring a chance of showers and thunderstorms
with isolated convection lingering over se IL thursday. Still
quite warm and humid Wed with highs in the lower 90s, with some
upper 80s nw of the IL river where more clouds arrive during the
day Wed. Highs Thu mostly in the mid 80s.
LONG TERM...Thursday night through Sunday
A quiet and cooler/less humid pattern expected during this time
with highs in the mid to upper 70s Fri into this weekend and lows
in the low to mid 50s. Large Canadian high pressure of 1027 mb
settles se into the Great Lakes region by Saturday morning and to
control IL`s weather for a few days. GFS and ECMWF models show a
disturbance moving ne toward central IL later in the weekend but
will keep a dry forecast since models first time showing this.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
408 PM CDT SAT SEP 7 2013
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 21Z...
* OUTFLOW BOUNDARY SURGING SOUTH-SOUTHWEST AND IS EXPECTED TO
PRODUCE A WIND SHIFT TO NORTHEAST AT BOTH ORD/MDW BETWEEN
2115-2130Z. WIND LIKELY TO GUST BRIEFLY AROUND 20 KT...THEN
BECOME MORE EAST/SOUTHEAST OVER NEXT FEW HOURS.
* SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING.
* SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
ALLSOPP/RATZER
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE IN OUTFLOW WINDSHIFT AT ORD...MEDIUM-HIGH MDW TO
NORTHEAST SHORTLY.
* MEDIUM-HIGH CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING
EARLY THIS EVENING.
* MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH
CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
ALLSOPP/RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
325 PM CDT SAT SEP 7 2013
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* DYING OUTFLOW BOUNDARY APPROACHING AIRPORT BUT NOT EXPECTED TO
CAUSE A WIND SHIFT AT ORD.
* SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING.
* SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
ALLSOPP
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING EARLY
THIS EVENING.
* MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH
CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
304 PM CDT SAT SEP 7 2013
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
WILL BE ISSUED SHORTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* DYING OUTFLOW BOUNDARY APPROACHING AIRPORT BUT NOT EXPECTED TO
CAUSE A WIND SHIFT AT ORD.
* SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING.
* SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
ALLSOPP
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING EARLY
THIS EVENING.
* MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH
CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
106 PM CDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 709 AM CDT SAT SEP 7 2013
FORCING IN THE 600-500MB LAYER IS CAUSING THE LINE OF SPRINKLES/LIGHT
SHOWERS AND THE ONE OR TWO THUNDERSTORMS ACROSS THE CWFA. WHERE
RAIN IS REACHING THE GROUND IT IS MAINLY A TRACE OR A FEW
HUNDREDTHS.
PER THE RAP TRENDS...THIS FEATURE WILL CLEAR THE CWFA BY MID
MORNING. ANOTHER AREA OF FORCING ARRIVES ALMOST IMMEDIATELY BEHIND
THE DEPARTING LINE. THUS ISOLATED TO SCATTERED SPRINKLES/LIGHT
SHOWERS CAN BE EXPECTED FOR THE MORNING.
DAYTIME HEATING WITH THE SECOND AND THEN THIRD ROUND OF FORCING
ALOFT IS EXPECTED TO INITIATE ISOLATED TO LOW END SCATTERED
SHOWERS AND SOME THUNDERSTORMS DURING THE AFTERNOON AND INTO THE
EVENING HOURS. ..08..
&&
.SYNOPSIS...
ISSUED AT 324 AM CDT SAT SEP 7 2013
06Z SFC ANALYSIS HAS WEAK LOWS AT KANW AND KSTC WITH WEAK
BOUNDARIES/FRONTS FROM THE NE/SD BORDER INTO MINNESOTA AND
WISCONSIN. DEW POINTS WERE MAINLY IN THE 60S ACROSS THE MIDWEST WITH
50S OVER THE EASTERN GREAT LAKES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT SEP 7 2013
RADAR TRENDS SHOW SHOWERS AND A FEW STORMS FROM EASTERN WISCONSIN
BACK THROUGH KAUW. SOME SPRINKLES WERE OCCURRING ACROSS CENTRAL IOWA.
SATELLITE AND MODELS SHOW A VERY WEAK SHORTWAVE MOVING FROM
MINNESOTA THROUGH WISCONSIN DURING THE DAY WHILE AN EVEN WEAKER ONE
PASSES TO THE SOUTH/WEST OF THE CWFA. AT BEST A FEW SPRINKLES MAY
OCCUR THIS MORNING ACROSS THE NORTHEAST CWFA.
THIS AFTERNOON...THE SITUATION IS MORE UNCERTAIN. WARM TEMPERATURES
ALOFT MAY PRECLUDE ANY DIURNAL CONVECTION FROM OCCURRING. HAVE OPTED
TO MAINTAIN THE SCHC POPS IN THE NORTHEAST CWFA FROM LATE AFTERNOON
ON. IF CONVECTION OCCURS...OVERALL COVERAGE MAY BE 5 PERCENT AT BEST.
MOISTURE POOLING NEAR THE FRONT/BOUNDARY SHOULD RESULT IN MID AND
UPPER 60 DEW POINTS ACROSS THE AREA. THIS MOISTURE COMBINED WITH
TEMPERATURES IN THE UPPER 80S TO MID 90S MAY PUSH HEAT INDEX VALUES
CLOSE TO 100 IN THE SOUTHWEST/WEST CWFA DURING THE AFTERNOON.
TONIGHT...THE OVERALL FORCING IS QUITE WEAK AND CONFINED RIGHT
AROUND THE FRONT/BOUNDARY AND BEHIND IT. THUS WILL MAINTAIN THE SCHC
POPS FOR TONIGHT BUT THE OVERALL SITUATION SUGGESTS A MAJORITY OF
THE AREA WILL REMAIN DRY TONIGHT. ..08..
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT SEP 7 2013
IN THE NEAR TERM THE MAIN CONCERN WITH BE RAIN CHANCES SUNDAY
ASSOCIATED WITH A STALLED FRONTAL BOUNDARY OVER NORTHERN MO. THE
SHORT RANGE MODELS SHOW THE SURFACE BOUNDARY JUST SOUTH OF THE
FORECAST AREA SUNDAY MORNING...BUT KEEP THE H8 BOUNDARY OVER THE
SOUTHERN CWFA. WITH WEAK CONVERGENCE NEAR THE H8 BOUNDARY AND
SURFACE BASED CAPES AROUND 2K J/KG A FEW STORMS ARE POSSIBLE. WEAK
FORCING AND WARM MID LEVEL TEMPS SHOULD KEEP COVERAGE OF SHRA/TSRA
ISOLATED SO KEPT POPS IN THE SLIGHT CHANCE RANGE.
THE LATE SUMMER/EARLY FALL HEAT WILL RETURN TO THE AREA MONDAY AS
THE SURFACE BOUNDARY LIFTS NORTH IN RESPONSE TO LOW PRESSURE MOVING
THROUGH THE NORTHERN PLAINS. AT THIS TIME IT APPEARS THE WARM FRONT
WILL NOT REACH THE NORTHERN CWFA UNTIL LATE AFTERNOON MAKING IT
UNLIKELY THAT THE 90 DEGREE TEMPERATURES WILL REACH NORTHWEST
IL...BUT THE REST OF THE AREA SHOULD SEE HIGHS IN THE LOW TO MID 90S.
SOUTHWEST WINDS SHOULD CONTINUE THROUGH THE NIGHT KEEPING TUESDAYS
LOWS NEAR 70. THE HOT WEATHER WILL CONTINUE TUESDAY AS A COLD
FRONT MOVES THROUGH NORTHWEST IA. GUSTY SOUTHWEST WINDS AHEAD OF
THE FRONT AND PLENTY OF SUN SHOULD HELP THE LOW LEVELS MIX TO AT
LEAST H8 YIELDING LOW TO MID 90S AGAIN FOR HIGHS. THE NORTHWEST MAY
BE THE EXCEPTION WITH CLOUDS EXPECTED TO INCREASE DURING THE
AFTERNOON SUPPRESSING THE HEATING SOME. A LOW THREAT OF SHRA/TSRA
WAS MENTIONED IN THE NORTH...SINCE THE FRONT WILL BE NEARBY 00Z.
TUESDAY NIGHT AND WEDNESDAY THE COLD FRONT WILL DROP SOUTH THROUGH
THE FORECAST AREA...BRINGING WITH IT THE BEST CHANCE OF RAIN MOST OF
THE AREA HAS HAD IN RECENT WEEKS. POPS STILL WERE KEPT IN THE HIGH
CHANCE CATEGORY MAINLY BECAUSE UPPER FLOW LOOKS CONVERGENT TUESDAY
NIGHT WHICH COULD HAMPER THE DEVELOPMENT OF SHRA/TSRA. CHANCE
POPS WERE CONTINUED OVER MOST OF THE AREA WEDNESDAY THEN TAPERED
BACK TO SLIGHT CHANCE FOR WEDNESDAY NIGHT AS THE FRONT MOVES SOUTH
OF THE FORECAST AREA. COOLER TEMPERATURES WILL SPREAD OVER THE AREA
FOR THE END OF THE WEEK. IMMEDIATELY BEHIND THE COLD FRONT HIGHS
WEDNESDAY WILL BE IN THE 80S. BY FRIDAY HIGHS IN THE 70S ARE
EXPECTED. OVERNIGHT LOWS SHOULD COOL INTO THE 50S BY FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1257 PM CDT SAT SEP 7 2013
SURFACE LOW...UPPER LEVEL DISTURBANCE AND APPROACHING COLD FRONT
TO COMBINE FOR AT LEAST SCATTERED SHOWERS AND STORMS BY LATE AFTN
THROUGH THIS EVE. BRIEF IFR TO MVFR VSBYS POSSIBLE WITH THE
STRONGER SHOWERS AND ANY STORMS. OVRNGT INTO SUN AM SOME OF THE
MODEL GUIDANCE SUPPORTIVE OF STRATUS AND FOG WITH IFR TO MVFR
CONDITIONS DEVELOPING WITH COOLER NORTHEASTERLY FLOW AND RESIDUAL
LOW LEVEL MOISTURE. WINDS THIS AFTERNOON WILL BE MAINLY FROM THE
SOUTHWEST 5-10 KTS WITH SOME LOCALIZED GUSTS NEAR 18 KTS. THIS
EVE FOR A TIME WINDS WILL BE LIGHT AND VARIABLE BEFORE SHIFTING TO
NORTH WITH FRONTAL PASSAGE AND EVENTUALLY BECOMING E/NE BY 12Z SUN.
SOME GUSTS OF 15-20 KTS POSSIBLE SUN AM.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
720 AM CDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 709 AM CDT SAT SEP 7 2013
FORCING IN THE 600-500MB LAYER IS CAUSING THE LINE OF SPRINKLES/LIGHT
SHOWERS AND THE ONE OR TWO THUNDERSTORMS ACROSS THE CWFA. WHERE
RAIN IS REACHING THE GROUND IT IS MAINLY A TRACE OR A FEW
HUNDREDTHS.
PER THE RAP TRENDS...THIS FEATURE WILL CLEAR THE CWFA BY MID
MORNING. ANOTHER AREA OF FORCING ARRIVES ALMOST IMMEDIATELY BEHIND
THE DEPARTING LINE. THUS ISOLATED TO SCATTERED SPRINKLES/LIGHT
SHOWERS CAN BE EXPECTED FOR THE MORNING.
DAYTIME HEATING WITH THE SECOND AND THEN THIRD ROUND OF FORCING
ALOFT IS EXPECTED TO INITIATE ISOLATED TO LOW END SCATTERED
SHOWERS AND SOME THUNDERSTORMS DURING THE AFTERNOON AND INTO THE
EVENING HOURS. ..08..
&&
.SYNOPSIS...
ISSUED AT 324 AM CDT SAT SEP 7 2013
06Z SFC ANALYSIS HAS WEAK LOWS AT KANW AND KSTC WITH WEAK
BOUNDARIES/FRONTS FROM THE NE/SD BORDER INTO MINNESOTA AND
WISCONSIN. DEW POINTS WERE MAINLY IN THE 60S ACROSS THE MIDWEST WITH
50S OVER THE EASTERN GREAT LAKES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT SEP 7 2013
RADAR TRENDS SHOW SHOWERS AND A FEW STORMS FROM EASTERN WISCONSIN
BACK THROUGH KAUW. SOME SPRINKLES WERE OCCURRING ACROSS CENTRAL IOWA.
SATELLITE AND MODELS SHOW A VERY WEAK SHORTWAVE MOVING FROM
MINNESOTA THROUGH WISCONSIN DURING THE DAY WHILE AN EVEN WEAKER ONE
PASSES TO THE SOUTH/WEST OF THE CWFA. AT BEST A FEW SPRINKLES MAY
OCCUR THIS MORNING ACROSS THE NORTHEAST CWFA.
THIS AFTERNOON...THE SITUATION IS MORE UNCERTAIN. WARM TEMPERATURES
ALOFT MAY PRECLUDE ANY DIURNAL CONVECTION FROM OCCURRING. HAVE OPTED
TO MAINTAIN THE SCHC POPS IN THE NORTHEAST CWFA FROM LATE AFTERNOON
ON. IF CONVECTION OCCURS...OVERALL COVERAGE MAY BE 5 PERCENT AT BEST.
MOISTURE POOLING NEAR THE FRONT/BOUNDARY SHOULD RESULT IN MID AND
UPPER 60 DEW POINTS ACROSS THE AREA. THIS MOISTURE COMBINED WITH
TEMPERATURES IN THE UPPER 80S TO MID 90S MAY PUSH HEAT INDEX VALUES
CLOSE TO 100 IN THE SOUTHWEST/WEST CWFA DURING THE AFTERNOON.
TONIGHT...THE OVERALL FORCING IS QUITE WEAK AND CONFINED RIGHT
AROUND THE FRONT/BOUNDARY AND BEHIND IT. THUS WILL MAINTAIN THE SCHC
POPS FOR TONIGHT BUT THE OVERALL SITUATION SUGGESTS A MAJORITY OF
THE AREA WILL REMAIN DRY TONIGHT. ..08..
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT SEP 7 2013
IN THE NEAR TERM THE MAIN CONCERN WITH BE RAIN CHANCES SUNDAY
ASSOCIATED WITH A STALLED FRONTAL BOUNDARY OVER NORTHERN MO. THE
SHORT RANGE MODELS SHOW THE SURFACE BOUNDARY JUST SOUTH OF THE
FORECAST AREA SUNDAY MORNING...BUT KEEP THE H8 BOUNDARY OVER THE
SOUTHERN CWFA. WITH WEAK CONVERGENCE NEAR THE H8 BOUNDARY AND
SURFACE BASED CAPES AROUND 2K J/KG A FEW STORMS ARE POSSIBLE. WEAK
FORCING AND WARM MID LEVEL TEMPS SHOULD KEEP COVERAGE OF SHRA/TSRA
ISOLATED SO KEPT POPS IN THE SLIGHT CHANCE RANGE.
THE LATE SUMMER/EARLY FALL HEAT WILL RETURN TO THE AREA MONDAY AS
THE SURFACE BOUNDARY LIFTS NORTH IN RESPONSE TO LOW PRESSURE MOVING
THROUGH THE NORTHERN PLAINS. AT THIS TIME IT APPEARS THE WARM FRONT
WILL NOT REACH THE NORTHERN CWFA UNTIL LATE AFTERNOON MAKING IT
UNLIKELY THAT THE 90 DEGREE TEMPERATURES WILL REACH NORTHWEST
IL...BUT THE REST OF THE AREA SHOULD SEE HIGHS IN THE LOW TO MID 90S.
SOUTHWEST WINDS SHOULD CONTINUE THROUGH THE NIGHT KEEPING TUESDAYS
LOWS NEAR 70. THE HOT WEATHER WILL CONTINUE TUESDAY AS A COLD
FRONT MOVES THROUGH NORTHWEST IA. GUSTY SOUTHWEST WINDS AHEAD OF
THE FRONT AND PLENTY OF SUN SHOULD HELP THE LOW LEVELS MIX TO AT
LEAST H8 YIELDING LOW TO MID 90S AGAIN FOR HIGHS. THE NORTHWEST MAY
BE THE EXCEPTION WITH CLOUDS EXPECTED TO INCREASE DURING THE
AFTERNOON SUPPRESSING THE HEATING SOME. A LOW THREAT OF SHRA/TSRA
WAS MENTIONED IN THE NORTH...SINCE THE FRONT WILL BE NEARBY 00Z.
TUESDAY NIGHT AND WEDNESDAY THE COLD FRONT WILL DROP SOUTH THROUGH
THE FORECAST AREA...BRINGING WITH IT THE BEST CHANCE OF RAIN MOST OF
THE AREA HAS HAD IN RECENT WEEKS. POPS STILL WERE KEPT IN THE HIGH
CHANCE CATEGORY MAINLY BECAUSE UPPER FLOW LOOKS CONVERGENT TUESDAY
NIGHT WHICH COULD HAMPER THE DEVELOPMENT OF SHRA/TSRA. CHANCE
POPS WERE CONTINUED OVER MOST OF THE AREA WEDNESDAY THEN TAPERED
BACK TO SLIGHT CHANCE FOR WEDNESDAY NIGHT AS THE FRONT MOVES SOUTH
OF THE FORECAST AREA. COOLER TEMPERATURES WILL SPREAD OVER THE AREA
FOR THE END OF THE WEEK. IMMEDIATELY BEHIND THE COLD FRONT HIGHS
WEDNESDAY WILL BE IN THE 80S. BY FRIDAY HIGHS IN THE 70S ARE
EXPECTED. OVERNIGHT LOWS SHOULD COOL INTO THE 50S BY FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 709 AM CDT SAT SEP 7 2013
MAINLY VFR WX WILL BE SEEN THROUGH 00Z/08. A WEAK DISTURBANCE
MOVING THROUGH IOWA/ILLINOIS WILL KEEP VCSH AT KMLI/KBRL THROUGH
15Z/07. DIURNAL SHRA/TSRA WILL BE POSSIBLE AFT 18Z/07 AND IF A
TSRA IMPACTS A TAF SITE...A BRIEF PERIOD OF MVFR WX WILL BE
POSSIBLE. A FRONT WILL MOVE THROUGH IOWA/ILLINOIS AFT 00Z/08
SHIFTING WINDS AROUND TO THE NORTHEAST. MVFR VSBYS MAY BE POSSIBLE
AFT 03Z/08 DUE TO HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...08
AREA FORECAST DISCUSSION
NWS TOPEKA KS
620 PM CDT Sun Sep 8 2013
.SHORT TERM...(This Evening through Monday)
Issued at 305 PM CDT SUN SEP 8 2013
At 2 PM, a weak surface trough was oriented from east to west across
northern Kansas on Sunday afternoon, co-located with the axis of
warmest 850 temperatures. A very weak front/outflow boundary with
minimal convergence in the low levels was stationary within 30 miles
of the Nebraska border as well, with a cluster of showers and
thunderstorms in extreme northeast Kansas and northwest Missouri.
Temperatures just to the south of the weak surface boundary have
become extremely warm, ranging from 99 to 104 degrees early this
afternoon, and while some drier air has mixed to the surface,
dewpoints remain in the lower to middle 60s. These conditions along
with the expectation for further heating through 4 PM have prompted
issuance of a heat advisory for heat index values in the 104 to 107
range.
Aside from the heat, potential for more vigorous thunderstorm
development is the other forecast focus today. The most recent runs
of the HRRR and NMM models continue to suggest thunderstorm
development on the warm side of the weak surface front by middle to
late afternoon, potentially linked to any outflow moving southwest
out of ongoing convection in NW Missouri. These storms are not
expected to be particularly organized or strong owing to only weak
to moderate CAPE and very weak vertical shear. However, it would
seem to be a rather favorable setup for microbursts given the dry
adiabatic to superadiabatic lapse rates from the surface to 700 hpa
and favorable downdraft CAPE. The primary uncertainty lies in
whether storms will actually develop over the deeply mixed airmass
as parcels would need to be lifted through a very deep mixed layer
before freely convecting. The best chance for storms would seem to
be northeast of a line from Belleville to Junction City to Ottawa.
Any storms should come to an end by 10 PM. Temperatures will fall
off nicely but a south breeze is expected to persist through the
night and will probably keep low temps in the low to mid 70s. Monday
will be quite hot once again, but with the upper ridge progressing
east of the area, 850 temps are forecast to drop by 2 to 3 degrees
from Sunday and highs may hold in the middle to upper 90s. Southwest
winds will be quite a bit stronger than Sunday with an increasing
pressure gradient. The southwest flow should also support greater
dry air advection into the forecast area which will probably support
very high fire danger with any dry vegetation.
Barjenbruch
.LONG TERM...(Monday Night through Sunday)
Issued at 305 PM CDT SUN SEP 8 2013
Monday night upper level trough progresses eastward through the
northern plains. As this system pushes into the Great Lakes region a
cold front will move southward into the region. Temperatures at 850
will cool significantly over the central plains as the shortwave
continues eastward and the upper high shifts into the OH river
valley. High temperatures reach the mid 90s area wide on Tuesday.
The front will approach the cwa on Tuesday evening and there is a
slight chance for showers and thunderstorms along the front mainly
across southern NE with an outside chance of reaching the northern
counties. Overnight Tuesday the front sags south into the cwa
increasing the chances for storms north of interstate 70s as the
progress of the front slows down. Due to cloud cover associated with
the possible precip high temperatures on Wednesday could remain in
the upper 80s to low 90s.
The front continues to slowly push south across the cwa therefore
have maintains pops through Friday. Convergence along the front and
upper level forcing appears to be rather weak, but cooler mid level
temps will allow for a weaker cap in place. Front exits the area
sometime on Thursday night or Friday as a shortwave digs southeast
through the eastern longwave trough. A surface high pressure will
build northeast of the region and likely control how far the front
is pushed southward. Once the front passes return flow isentropic
lift may generate precip mainly across central and western KS
possible spreading into our western counties. Next weekend another
front will possibly move into the central plains. Temperatures look
to gradually cool behind the front with high temperatures in the
upper 70s to low 80s by Friday, and low temperatures generally in
the upper 50s to low 60s.
&&
.AVIATION...(For the 00Z TAFs through 00Z Monday Evening)
Issued at 620 PM CDT SUN SEP 8 2013
Vfr conditions will prevail at all terminals through the fcst period.
Sustained south to southwest winds under 10 kts through 12z will
increase into the 13-15kt range by 15z with gusts over 20 kts thru
the remainder of the fcst period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY until 7 PM CDT this evening FOR KSZ021>024-026-036-
038>040-054>056-058-059.
&&
$$
SHORT TERM...Barjenbruch
LONG TERM...Sanders
AVIATION...63
AREA FORECAST DISCUSSION
NWS JACKSON KY
728 PM EDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 728 PM EDT SUN SEP 8 2013
UPDATED TO REMOVE SHOWERS AND THUNDERSTORMS AND REDUCE CLOUD COVER AS
SKIES HAVE CLEARED OFF NICELY THIS EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 335 PM EDT SUN SEP 8 2013
18Z SFC ANALYSIS SHOWS A COLD FRONT DISSIPATING OVER EAST KENTUCKY.
THIS BOUNDARY HAS NOT BROUGHT AN AIR MASS CHANGE AND HAS NOT BEEN
ABLE TO GENERATE MUCH IN THE WAY OF CONVECTION FOR EAST KENTUCKY...SO
FAR. HOWEVER...THERE ARE A FEW SHOWERS GOING UP NOT TOO FAR FROM
US. STILL THINK THAT A SOME SHOWERS AND POSSIBLY A THUNDERSTORM WILL
OCCUR OVER PARTS OF EAST KENTUCKY...MAINLY SOUTH OF JKL...THROUGH
SUNSET. SKIES HAVE BEEN PARTLY TO MOSTLY CLOUDY THROUGH THE AREA THIS
AFTERNOON WITH THE SUNSHINE HELPING TEMPERATURES CLIMB INTO THE LOWER
AND MID 80S IN MOST LOCATIONS. MEANWHILE...DEWPOINTS HAVE SLIPPED A
BIT...MIXING DOWN TO THE LOW TO MID 60S THOUGH THE WINDS HAVE BEEN
GENERALLY LIGHT.
THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH A SMALL SHORTWAVE PASSING
BY TO THE NORTHEAST TONIGHT...WHILE AN MCV WILL SLIP SOUTH WELL TO
THE WEST OF THE AREA. RIDGING THEN BUILDS BACK OVER THE AREA EARLY
MONDAY...RUNNING EAST OVER KENTUCKY DURING THE DAY AND INTO THE
NIGHT. WITH THE GOOD MODEL AGREEMENT...HAVE AGAIN FOLLOWED THE HIGHER
RESOLUTION NAM12 FOR DETAILS...ALONG WITH SOME HRRR INFLUENCE IN THE
NEAR TERM.
SENSIBLE WEATHER WILL FEATURE WIDELY SCATTERED SHOWERS AND THE ODD
THUNDERSTORM...FADING OUT BY SUNSET ALONG WITH MUCH OF THE CLOUDS.
THIS WILL SET THE STAGE FOR ANOTHER MILD NIGHT WITH PATCHY FOG
DEVELOPING TOWARD DAWN...MAINLY IN THE VALLEYS. THE RIDGE BUILDING
ALOFT ON MONDAY WILL WIPE OUT THE REMAINS OF THE FRONT AND LIMIT ANY
CONVECTION TO JUST A VERY SMALL THREAT ALONG THE VIRGINIA BORDER AT
PEAK HEATING. IT WILL ALSO BE A VERY WARM DAY WITH TEMPERATURES
APPROACHING 90 DEGREES IN SOME LOCATIONS BY LATE AFTERNOON. ANOTHER
MILD NIGHT WITH PATCHY VALLEY FOG FOLLOWS INTO TUESDAY MORNING.
AGAIN USED THE CONSSHORT AND ITS BIAS CORRECTED KIN TO JUMP START
THE TD AND WIND GRIDS THROUGH 12Z MONDAY AND THE CONSALL THEREAFTER.
FOR TEMPERATURES...PREFERRED THE OBS DATABASE AS A BASIS FOR THE
DIURNAL CURVE AND MODIFIED CONSALL FOR MAX AND MIN TEMPS. AGAIN DID
NOT DO TOO MUCH TERRAIN ADJUSTMENT AT NIGHT GIVEN THE HIGHER DEWS AND
SOME CLOUD COVER EXPECTED TO BE AROUND. AS FOR POPS...ENDED UP PRETTY
CLOSE TO AN AVERAGE OF THE GUIDANCE THROUGH THE SHORT TERM PERIOD.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 320 PM EDT SUN SEP 8 2013
THE MODELS WERE NOT IN THE BEST AGREEMENT THIS TIME AROUND WITH THE
SURFACE DETAILS. THE UPPER AIR PATTERN...HOWEVER...WAS GENERALLY THE
SAME BETWEEN THE HPC...GFS...ECWMF MODEL OUTPUTS. THE PERIOD IS
PROGGED TO START OUT WITH A LARGE RIDGE OF HIGH PRESSURE PARKED
ACROSS THE SOUTHEASTERN CONUS. WEAK MARGINALLY MOIST FLOW AROUND THE
WESTERN EDGE OF THE HIGH COULD LEAD TO ISOLATED SHOWER AND STORM
ACTIVITY TUESDAY AFTERNOON AND EVENING. THE GFS AND SREF WERE ALSO
ON BOARD WITH THIS PATTERN. BASED ON THE LATEST MEXMOS AND ECEMOS
GUIDANCE...THERE WOULD BE A CHANCE OF RAIN IN THE FORECAST EACH DAY
FROM TUESDAY THROUGH THURSDAY NIGHT. THAT BEING SAID...AND WITH THE
LATEST RUNS OF THE GFS AND ECWMF BOTH IN GOOD AGREEMENT...DECIDE TO
INCLUDE A CHANCE OF RAIN IN THE FORECAST THROUGH LATE THURSDAY
NIGHT. THE BEST CHANCE FOR RAIN LOOKS TO BE THURSDAY AND THURSDAY
EVENING...AS A FAIRLY STRONG COLD FRONT MOVES ACROSS THE AREA.
TEMPERATURES AHEAD OF THE FRONT WILL BE QUITE WARM...WITH HIGHS
TOPPING OUT IN THE MID TO UPPER 80S ACROSS THE AREA TUESDAY THROUGH
THURSDAY. EASTERN KENTUCKY WILL BE ENTRENCHED IN A PERSISTENT
SOUTHERLY FLOW REGIME AS AN AREA OF HIGH PRESSURE REMAINS IN PLACE
ACROSS THE AREA. THE PRESENCE OF CLOUDS AND ISOLATED SHOWERS AND
STORMS SHOULD BE ENOUGH TO KEEP TEMPERATURES AROUND EASTERN KENTUCKY
FROM REACHING THE EXTREMELY WARM MOS VALUES(THE LATEST MEXMOS HAS A
FEW LOCATIONS AROUND THE AREA REACHING THE LOWER 90S ON TUESDAY). A
DRAMATIC COOL DOWN IS IN STORE FOR THE END OF THE WEEK...AS A COOL
AND DRY CANADIAN AIR MASS SETTLES OVER THE AREA BEHIND THE DEPARTING
COLD FRONT. DAYTIME HIGHS ON FRIDAY AND SATURDAY WILL NOT GET OUT
OF THE 70S...WITH HIGHS ON SATURDAY POSSIBLE ONLY MAKING IT INTO THE
LOW TO MID 70S. OVERNIGHT LOWS WILL BE QUITE WARM AT FIRST...WITH
VALUES AROUND 70 COMMON TO START THE PERIOD. THINGS WILL COOL OFF
QUITE A BIT AFTER THAT...WITH LOWS AROUND 60 POSSIBLE THURSDAY
NIGHT...AND DROPPING INTO THE LOWER 50S FRIDAY NIGHT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 728 PM EDT SUN SEP 8 2013
VFR CONDITIONS SHOULD MAINLY DOMINATE THROUGH THE TAF FORECAST PERIOD
WITH A PERIOD OF LIGHT MVFR VALLEY FOG LATE TONIGHT. LIGHT WINDS ARE
ANTICIPATED.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
403 PM EDT SAT SEP 7 2013
.SHORT TERM...THIS EVENING TONIGHT
DIRECT CYCLONIC VORTICITY ADVECTION WAS EFFICIENT ENOUGH TO ALLOW
WIDESPREAD PRECIPITATION TO FALL OUT OF A MIDCLOUD DECK 8-10KFT
AGL...THROUGHOUT MUCH IF NOT ALL OF SOUTHEASTERN MICHIGAN EARLIER
THIS AFTERNOON. A DRY ATMOSPHERE BELOW 8000FT AGL...COMPOUNDED TO
THE FORECAST DIFFICULTY.
THE QUESTION REMAINS WHAT SORT OF RECOVERY CAN HAPPEN HERE ON AN
EARLY SEPTEMBER AFTERNOON WITH OPAQUE CLOUDS ABOVE...AND A
EVAPORATIVE/RAIN COOLED NEAR SURFACE LAYER BELOW. SURFACE
OBSERVATIONS ARE SHOWING SOME LOW 80S CREEPING INTO WESTERN LOWER
MICHIGAN AND SOME BREAKS IN THE CLOUDS EAST OF THE ANVIL OVER FAR
SOUTHEASTERN WISCONSIN. THE LEGITIMATE COLD FRONT IS CURRENTLY UP
OVER PORTIONS OF NORTHERN LAKE HURON...NORTH OF ROGERS CITY AND
PRESQUE ISLE. GIVEN THE BREAKS WITH UNIFORM SOUTHWESTERLY FLOW STILL
EXPECT TEMPERATURES TO CLIMB ABOVE 80 DEGREES. RAP BASED SPC
MESOANALYSIS DOES SHOW SOME OF THIS RECOVERY WITH MLCAPES AT/AROUND
1000 J/KG INVOF MIDLAND COUNTY THUNDERSTORM. THEREFORE...MUCH OF THE
INFORMATION PROVIDED IN THE MORNING UPDATE DISCUSSION REMAINS VALID.
NEW INFORMATION IS THE MIDLAND THUNDERSTORM/CELL THAT IS SHOWING
ORGANIZATION WITH SOME FORWARD LEAN AND DECENT MIDLEVEL CONVERGENCE.
THEREFORE...THUNDERSTORMS ARE STILL EXPECTED TO POSE AN ISOLATED
RISK OF STRONG WINDS. BETTER POTENTIAL REMAINS OVER THE NORTHERN CWA
20-01Z...A BRIEF WINDOW ACROSS THE SOUTHERN CWA 00-03Z.
THE COLD FRONT SHOULD PUSH STEADILY THROUGH THE CWA FROM NORTH TO
SOUTH BETWEEN 03-12Z. LOW STRATUS ALREADY EXISTS NORTH OF LAKE
HURON/GEORGIAN BAY AND MAY BE SHOWING A PRECURSOR TO TOMORROW
MORNING...WHERE AT LEAST A FRACTION OF THE NWP IS SHOWING A LOW
STRATUS BLANKET 12Z.
&&
.LONG TERM...SUNDAY THROUGH NEXT SATURDAY
COLD FRONT WILL HAVE CLEARED THE STATE LINE BY SUNDAY MORNING
LEAVING HIGH PRESSURE TO BUILD IN DURING THE DAY. CONSIDERATION OF
MOISTURE FLUX OFF LAKE HURON IN COMBINATION WITH FORECAST SOUNDINGS
CONTINUE TO SUPPORT THE IDEA OF MOSTLY CLOUDY SKIES TO START THE DAY
ACROSS SOUTHEAST MICHIGAN...AS MOISTURE LOCKS IN UNDER AND
INVERSION. MUCH DRIER AIR SHOULD START TO ARRIVE FROM CANADA DURING
THE AFTERNOON...AND SHOULD ERODE THE CLOUD DECK AS IT MIXES DOWN TO
THE SURFACE. DRIZZLE COULD BE A POSSIBILITY IF THE LOW LEVELS BECOME
SATURATED ENOUGH UNDER THE DRIER AIR ARRIVING ABOVE THE
INVERSION...ALTHOUGH IT IS NOT MENTIONED IN THE FORECAST AT THIS
TIME. CURRENT FORECAST SOUNDINGS DO NOT LOOK SATURATED ENOUGH TO
JUSTIFY A MENTION...HOWEVER CAN SEE POTENTIAL FOR MODELS TO
UNDERPLAY MOISTURE OFF LAKE HURON IN THE LOWER LEVELS. THIS WILL BE
A SHORTER-TERM FORECAST CONCERN. THE COMBINATION OF COLD AIR
ADVECTION AND NORTHEAST FLOW OFF THE LAKES WILL KEEP TEMPERATURES
COOL TOMORROW...ONLY REACHING INTO THE 60S ACROSS THE THUMB AND NEAR
THE LAKESHORES...AND IN THE LOW/MID 70S FURTHER INLAND.
UPPER LOW OVER BRITISH COLUMBIA AND WASHINGTON STATE WILL TRACK
EAST...OPENING AND MOVING INTO UPPER MIDWEST/SOUTHERN CANADA BY
MONDAY NIGHT. SURFACE LOW PRESSURE WILL BECOME ORGANIZED OVER THE
NORTHERN PLAINS AND MIDWEST ON MONDAY...WHICH WILL ALLOW A WARM
FRONT TO LIFT ACROSS MICHIGAN. MODELS ARE NOW SHOWING A GOOD PUSH OF
THETA-E ADVECTION AND A BAND OF GOOD SYSTEM RELATIVE ISENTROPIC
ASCENT AS A WARM FRONT AND LOW-LEVEL JET LIFT THROUGH DURING THE
LATE MORNING AND AFTERNOON. THIS MAY BE ENOUGH FORCING TO ALLOW A
BAND OF SHOWERS/TSTORMS TO MOVE THROUGH BEFORE WE BECOME ENTRENCHED
IN A MORE STABLE WARM SECTOR.
IMPRESSIVE WARM AIR ADVECTION LOOKS TO OCCUR LATE MONDAY THROUGH
TUESDAY AS THE LOW MOVES INTO THE NORTHERN GREAT LAKES AND STRONG
SOUTH TO SOUTHWEST FLOW CONTINUES TO PUMP WARMER AIR INTO THE AREA.
FORECAST SOUNDINGS LOOK EXTREMELY CAPPED PRIOR TO 18Z...UNTIL DEEPER
MIXING STARTS TO CHIP AWAY AT THE INVERSION. LOOKS LIKE ENOUGH OF AN
INVERSION WILL HOLD TO KEEP A DRY FORECAST...IN ADDITION TO THE COLD
FRONT REMAINING UPSTREAM DURING THE DAY. TUESDAY LOOKS BREEZY AND
HOT AS H850 TEMPERATURES RISE TO 20-22C AND ENOUGH MIXING LOOKS
PRESENT TO REALIZE ALL THE WARMING ALOFT. SOME SUNSHINE SHOULD HELP
BOOST TEMPERATURES INTO THE LOW OR EVEN MID 90S. BREEZY
CONDITIONS...POSSIBLY EVEN WINDY...ALSO LOOK LIKELY WITH GFS/NAM
SOUNDINGS SHOWING A SOLID CORE OF 20 KNOTS EVEN AT THE VERY BOTTOM
OF THE MIXED LAYER...WITH HIGHER SPEEDS EVEN FURTHER UP. BIGGEST
CONCERN FOR THIS DAY WILL ACTUALLY BE FOR FIRE WEATHER INTERESTS
WITH HOT AND BREEZY CONDITIONS. DEWPOINTS LOOK TO SETTLE INTO THE
MID 60S (PER GFS SOUNDINGS) BUT COULD GO LOWER IF DRIER NAM
VERIFIES. THIS SHOULD KEEP MIN RELATIVE HUMIDITIES ABOVE 30 PERCENT.
WILL WATCH TRENDS HOWEVER.
COLD FRONT WILL DROP THROUGH TUESDAY EVENING THROUGH WEDNESDAY
MORNING...WITH LOW-LEVEL FORCING AIDED BY RIGHT ENTRANCE REGION
FORCING ALOFT. THIS SHOULD PROVIDE AT LEAST A SCATTERED COVERAGE OF
SHOWERS/TSTORMS ACROSS THE AREA AS THE FRONT DROPS THROUGH.
UPPER TROUGHING WILL SET UP OVER THE GREAT LAKES WEDNESDAY THROUGH
THURSDAY...WITH UPPER SHORTWAVES ROTATING THROUGH THE MAIN TROUGH
SENDING REINFORCING SHOTS OF COLD AIR DOWN INTO THE GREAT LAKES.
THIS SHOULD DROP TEMPERATURES BACK DOWN TO BELOW NORMAL FOR THE END
OF THE WEEK...EVEN AS HIGH PRESSURE BUILDS BACK IN ON FRIDAY.
&&
.MARINE...
THE PASSAGE OF A COLD FRONT TONIGHT WILL USHER IN A SOLID 12 HOUR
PERIOD OF STRONG NORTH NORTHEAST WINDS THAT WILL GUST TO NEAR GALES
ACROSS THE OPEN WATERS OF CENTRAL LAKE HURON AND POSSIBLY OUTER
SAGINAW BAY AND THE EXPOSED NEARSHORE WATERS OF THE THUMB.
LIKEWISE...THESE SAME LOCATIONS WILL SEE SIGNIFICANT WAVE HEIGHTS
BUILD INTO THE 6 TO 8 FOOT RANGE DURING THIS TIME PERIOD WITH THE
REMAINING NEARSHORE ZONES GENERALLY EXPERIENCING SIG WAVES OF 6 FEET
OR LESS. WINDS WILL EASE BY SUNDAY EVENING FOLLOWED BY SUBSIDING
WAVES BY LATE SUNDAY NIGHT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED
ACCORDINGLY FOR ALL NEARSHORE ZONES OF LAKE HURON. A REDUCED FETCH
FOR THE SOUTHERN WATERS OF LAKE SAINT CLAIR AND MICHIGAN WATERS OF
LAKE ERIE WILL LIMIT THEIR SIG WAVES TO AROUND 3 FEET.
&&
.AVIATION...ISSUED 144 PM EDT SAT SEP 7 2013
//DISCUSSION...
TWO TIME WINDOWS FOR PRECIPITATION THIS AFTERNOON. THE FIRST IS WITH
ONGOING SHOWER ACTIVITY WITH VFR CEILINGS AND A MID CLOUD DECK. THIS
ACTIVITY WILL PUSH EASTWARD DURING THE FIRST COUPLE OF HOURS OF THE
TAF PERIOD. THEN POTENTIAL EXISTS FOR THUNDERSTORM DEVELOPMENT AHEAD
OF AN APPROACHING COLD FRONT BOUNDARY. DID GO AGGRESSIVE WITH TIMING
A 3 HOUR TEMPO GROUP FROM NORTH TO SOUTH. THE SUPPORT FOR SHOWER AND
THUNDERSTORMS SHOULD END AT THE SOUTHERN TAF SITES BETWEEN 0-2Z.
FOR DTW...PREVAILING SOUTHWEST FLOW WILL CONTINUE BEFORE A MORE
ABRUPT SHIFT TO THE NORTHEAST TAKES PLACE WITH THE PASSAGE OF THE
SURFACE TROUGH TONIGHT AROUND 04Z.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE THAT CEILING HEIGHTS WILL LOWER BELOW 5000 FT
AFTER 6Z TONIGHT.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO PORT SANILAC...FROM 2 AM SUNDAY TO 10 PM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...FROM 5 AM SUNDAY TO 4 AM MONDAY.
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 5 AM SUNDAY TO 4 PM
SUNDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
MI WATERS OF LAKE ERIE...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
&&
$$
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
AVIATION.....CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
140 PM EDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1057 AM EDT SAT SEP 7 2013
TRICKY FORECAST FOR THE REST OF TODAY...AS THE COLD FRONT CONTINUES
TO SLIDE SOUTH ACROSS THE SOUTHEAST PART OF UPPER MICHIGAN. THE
THUNDERSTORMS ASSOCIATED WITH THIS FRONT HAVE NEARLY LEFT CWA IN
LAKE MICHIGAN. OTHER THAN A FEW SHOWERS REDEVELOPING OVER
DICKINSON/MENOMINEE COUNTIES THIS AFTERNOON...THE SHOWERS
ASSOCIATED WITH THE FRONT SHOULD BE DONE.
ATTENTION THEN TURNS TO THE CLOUDINESS OVER LAKE SUPERIOR. VISIBLE
SATELLITE SHOWS TWO CLOUD DECKS...WITH MID CLOUDS SHIFTING
EAST-SOUTHEAST AND A LOW STRATUS DECK DROPPING SOUTH TO
SOUTH-SOUTHWEST. THERE WAS SOME UNCERTAINTY ON IF THE CLOUDS WERE
FOG OR LOW STRATUS...AS WEBCAMS ALONG LAKE SUPERIOR IN THE KEWEENAW
AND EAST WEREN/T POINTING ONE WAY OR ANOTHER. BUT THE 1435Z OB FROM
KCMX HAS INDICATED IT IS MORE OF A LOW STRATUS WITH SOME FOG OR
DRIZZLE. THUS...WILL ADJUST THE FORECAST FOR LOCATIONS NEAR LAKE
SUPERIOR FOR MORE CLOUDINESS THIS AFTERNOON UNDER THE
NORTH-NORTHEAST WINDS. BASED OFF THE THICKNESS OF THE LOW CLOUDS ON
THE LATEST RAP RUNS...WILL ADD A MENTION OF DRIZZLE TO THE HIGHER
TERRAIN OF NORTH CENTRAL AND THE KEWEENAW DURING THE AFTERNOON.
THIS COOL FLOW OFF LAKE SUPERIOR WILL ALSO LEAD TO TEMPERATURES
FALLING THROUGH THE AFTERNOON FROM THE CURRENT VALUES IN THE LOWER
70S AND INTO THE MID-LOWER 60S TOWARDS EVENING. UPDATED GRIDS WILL
BE OUT SHORTLY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 519 AM EDT SAT SEP 7 2013
GENERALLY DECAYING SHOWERS AND THUNDERSTORMS HAVE BEEN THE
RULE...AND DESPITE ALL THE MOISTURE AROUND FOG HAS BEEN SLOW TO
MATERIALIZE ANYWHERE THAT HAD LESS THAN 0.25IN OF RAIN OVER THE PAST
24 HOURS. FOG OVER W AND E LAKE SUPERIOR TO PUSH S BEHIND THE COLD
FRONT SET UP FROM NW WI THROUGH THE KEWEENAW AND NE LAKE SUPERIOR.
THIS BOUNDARY WILL BE ENOUGH TO SPARK THE POTENTIAL OF ADDITIONAL
SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI LATE
THIS MORNING AND EARLY THIS AFTERNOON...BEFORE SIGNIFICANTLY
COOLER/DRIER AIR WORKS IN. MODEL TIMING ON THE COLD FRONT IS
REASONABLE...SLIPPING TO FAR S CENTRAL PORTIONS OF THE CWA BY 18Z.
EXPECT SLOWLY FALLING TEMPS THIS AFTERNOON OVER THE N AS A
RESULT...AS CLOUD COVER BEGINS TO DIMINISH. KEPT WITH THE COOL TEMPS
TONIGHT ON NNE FLOW AND 850MB TEMPS FALLING TO A CWA AVG 9C. PW
VALUES SHOULD FALL FROM AROUND 150 PERCENT OF NORMAL /1.5IN/ THIS
MORNING TO A 40-50 PERCENT OF NORMAL BY 12Z SUNDAY /0.35-0.4IN/.
LOWERED THE TRADITIONAL COOL SPOTS A BIT MORE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 505 AM EDT SAT SEP 7 2013
IN THE LONG TERM...PATTERN IN THE MEAN WILL CONTINUE TO FEATURE A NW
CANADA RIDGE AND ERN N AMERICA TROF. THIS WILL RESULT IN SHORTWAVES
PERIODICALLY DROPPING SE FROM THE NW RIDGE INTO THE ERN TROF. TWO
MORE SIGNIFICANT WAVES WILL BRING NOTABLE AMPLIFICATION OF THE ERN
TROF. THE FIRST WILL BE THIS WEEKEND AND THE SECOND WILL BE LATE IN
THE UPCOMING WEEK. THE SECOND AMPLIFICATION LOOKS LIKE IT WILL BRING
THE COOLEST AIR TO THE UPPER LAKES...POSSIBLY POSING A RISK OF THE
FIRST WIDESPREAD FROST OF THE SEASON LATE WEEK. BTWN THE 2 SURGES OF
COOL AIR...TEMPS WILL BE AT OR ABOVE NORMAL. UNDERNEATH THE LARGER
SCALE RIDGE/TROF PATTERN...MID LEVEL LOW CURRENTLY OVER ERN WA WILL
OPEN UP AND SHIFT GENERALLY E ROUGHLY ALONG THE U.S./CANADA
BORDER...AFFECTING THE UPPER LAKES MON/TUE. THIS SYSTEM SHOULD BRING
THE BEST CHANCE OF PCPN DURING THE LONG TERM PORTION OF THE FCST.
FARTHER DOWN THE ROAD...GUIDANCE SUGGESTS THE NW CANADA RIDGE WILL
BE REPLACED BY A TROF...RESULTING IN DOWNSTREAM HEIGHT RISES ACROSS
THE CNTRL CONUS. SO...A WARM PERIOD MAY BE SHAPING UP BEYOND THIS 7
DAY FCST.
BEGINNING SUN...ON THE BACKSIDE OF THE AMPLIFYING ERN TROF...
CANADIAN HIGH PRES WILL SETTLE SE OVER THE UPPER GREAT LAKES. ONLY
FCST CONCERN CONTINUES TO BE THE POTENTIAL FOR SOME MORNING LOW
CLOUDS OFF LAKE SUPERIOR IN UPSLOPE N/NE FLOW. THE NAM IS COOLEST IN
BRINGING 850-875MB TEMPS DOWN TO AROUND 5C ACROSS LAKE SUPERIOR AT
12Z SUN. OTHER GUIDANCE IS AROUND 2C WARMER. IF THE COOLER NAM IS
CORRECT...WATER TEMPS AS HIGH AS 16-18C OVER SRN LAKE SUPERIOR WILL
BE SUFFICIENT FOR STRATOCU OFF THE LAKE. SINCE LOW CLOUDS ARE
EVIDENT OVER HUDSON BAY INTO ADJACENT NRN MANITOBA/NRN ONTARIO AND
SINCE WIND FLOW AHEAD OF HIGH MAY TEND TO ADVECT SOME OF THIS
SHALLOW MOISTURE INTO THE AREA...OPTED TO RETAIN SOME CLOUD COVER
SUN MORNING NEAR LAKE SUPERIOR EVEN IN FAVORING GUIDANCE WARMER THAN
THE NAM. UPSLOPE CLOUDS SHOULDN`T STICK AROUND LONG UNDER
INCREASINGLY ANTICYCLONIC LOW-LEVEL FLOW...ADVECTION OF DRIER AIR
AND DAYTIME HEATING. FARTHER INLAND...MAY SEE A BLOSSOM OF SCT TO
PERHAPS BKN CU/STRATOCU FOR JUST A BRIEF TIME BEFORE DAYTIME HEATING
MIXES OUT LOW-LEVEL MOISTURE. THE AFTN HRS SHOULD FEATURE ABUNDANT
SUNSHINE ACROSS THE BOARD. TEMPS WILL BE ON THE COOL SIDE OF NORMAL
DESPITE THE SUNSHINE. MIXING TO THE INVERSION BASE ON FCST SOUNDINGS
YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING INFLUENCE OF THE
GREAT LAKES.
SUN NIGHT...MIDLEVEL LOW CURRENTLY OVER ERN WA WILL HAVE OPENED UP
AND WILL REACH SRN SASKATCHEWAN/ERN MT BY 12Z MON. IN RESPONSE...
DEVELOPING LOW-LEVEL JET WILL SHIFT ACROSS THE DAKOTAS INTO MN
DURING THE NIGHT. THE ECMWF CONTINUES TO BE THE FASTEST SPREADING
PCPN INTO UPPER MI SUN NIGHT IN ASSOCIATION WITH A LEAD MINOR
SHORTWAVE MOVING INTO THE UPPER LAKES. THE UKMET HAS NOW FOLLOWED
SUIT. THE GFS HAS PCPN REACHING THE FAR W OVERNIGHT. MEANWHILE...THE
NAM/GEM MAINTAIN STRONGER SFC HIGH PRES RIDGING BACK INTO THE UPPER
LAKES AND THUS KEEP PCPN W OF UPPER MI THRU 12Z MON. FOR NOW...PLAN
TO MAINTAIN CONTINUITY WITH THE LAST FEW FCST CYCLES AND WILL ONLY
BRING SCHC POPS INTO THE FAR W OVERNIGHT...SIMILAR TO THE GFS WHICH
REPRESENTS A GOOD COMPROMISE BTWN THE ECMWF/UKMET AND GEM/NAM.
OTHERWISE...SOUTHERLY RETURN FLOW OF WARMER/MOISTER AIR AND AN
INCREASE IN CLOUDS WILL RESULT IN A WARMER NIGHT MOST AREAS...
ESPECIALLY OVER THE W WHERE GRADIENT WILL BE TIGHTENING FIRST AND
WHERE CLOUDS WILL ARRIVE EARLIEST. LINGERING DRY AIR MASS IN THE
EVENING COMBINED WITH INITIALLY CLEAR SKIES AND LIGHT/CALM WIND OVER
THE E MAY ALLOW TEMPS AT TRADITIONAL INTERIOR COLD SPOTS TO FALL
INTO THE LWR 40S.
MON/TUE...MAIN SHORTWAVE WILL CONTINUE TO TRACK E...PASSING ACROSS
THE UPPER LAKES MON NIGHT/TUE. WHILE TIMING OF FEATURE HAS
IMPROVED...TRACK OF ASSOCIATED SFC LOW REMAINS MORE UNCERTAIN.
THE ECMWF HAS TRENDED S AND HAS SFC LOW TRACKING ACROSS UPPER MI...
NOT TOO DIFFERENT FROM THE NAM. ONLY SCNTRL AND ERN UPPER MI MAY
SLIP INTO THE WARM SECTOR MON NIGHT. END RESULT WOULD PROBABLY BE
FAIRLY WIDESPREAD SHRA/TSRA ACTIVITY ACROSS THE FCST AREA MON...
ESPECIALLY NRN PORTIONS. THE GFS/GEM ARE FARTHER N (GEM HAS BEEN ALL
ALONG) AND HAVE SFC LOW TRACKING OVER OR JUST N OF LAKE SUPERIOR.
RESULT WOULD BE SHRA/TSRA ACTIVITY N OF WARM FRONT BEING SHIFTED
FARTHER N...PERHAPS MOSTLY N OF UPPER MI MON/MON NIGHT. WITH THE
ECMWF NORMALLY PROVIDING BETTER GUIDANCE AND WITH 2 CONSECUTIVE RUNS
NOW SHOWING THE FARTHER S TRACK...HEDGED FCST SLIGHTLY IN THAT
DIRECTION WHICH RESULTED IN INCREASING POPS/QPF A BIT ACROSS THE N
MON/MON NIGHT. EFFECTIVE SHEAR MON LOOKS BE ON THE ORDER OF
30-40KT...SUPPORTING THE POTENTIAL OF STRONG TO SVR STORMS...BUT
MUCH WILL DEPEND ON THE MAGNITUDE OF INFLOW INSTABILITY FOR THE
ELEVATED STORMS. EVEN THE GFS WITH ITS FARTHER N SFC LOW TRACK IS
SLOW TO BRING SUFFICIENT INSTABILITY N FOR STRONG/SVR STORMS MON.
BETTER POTENTIAL OF SVR STORMS SHOULD BE MON NIGHT AS INSTABILITY
AXIS SHIFTS INTO THE UPPER LAKES. HOWEVER...IF WARM FRONT LIFTS N OF
THE AREA...EXPECTED ARRIVAL OF COLD FRONT LATE NIGHT INTO TUE
MORNING WOULD BE MORE IN SYNC WITH DIURNAL MIN...SUGGESTING A
DIMINISHED SVR THREAT. IF WARM FRONT ONLY LIFTS INTO UPPER MI...THEN
THERE WOULD BE THE POTENTIAL FOR ELEVATED SVR STORMS N OF FRONT MON
NIGHT. AT LEAST WITH SHORTWAVE RAPIDLY WEAKENING AS IT MOVES ACROSS
THE UPPER LAKES...THERE DOES NOT APPEAR TO BE A POTENTIAL FOR
WIDESPREAD SVR STORMS. LATEST SPC OUTLOOK ONLY HAS PORTIONS OF UPPER
MI IN A 5 PCT RISK WHICH APPEARS REASONABLE AT THIS TIME. ON TUE...
SHRA/TSRA CHANCES SHOULD BE MOSTLY CONFINED TO THE ERN FCST AREA AS
SFC LOW/COLD FRONT WILL STILL NEED TO PASS THRU THAT AREA.
HEADING INTO WED/THU...THE ECMWF HAS CONTINUED TO BACK OFF ON ITS
FARTHER W AND MUCH MORE SHARPLY DIGGING SHORTWAVE INTO THE UPPER
MISSISSIPPI VALLEY AND GREAT LAKES. NOW...MEDIUM RANGE GUIDANCE IS
GENERALLY WELL CLUSTERED WITH THE TROF AMPLIFICATION OCCURRING THRU
THE GREAT LAKES AND THEN INTO NEW ENGLAND LATE WEEK. WITH MUCH OF
THE DEEP MOISTURE SWEPT OUT OF THE AREA BY THE PRIOR SHORTWAVE...
NOTHING MORE THAN LOW CHC POPS APPEAR WARRANTED WED AS COLD FRONT
DROPS THRU THE UPPER LAKES. SHRA CHANCES MAY LINGER THRU THU WITH
HINTS OF ANOTHER WAVE DROPPING ACROSS THE AREA INTO THE AMPLIFYING
TROF. THU WILL FEEL LIKE AUTUMN AS COOL AIR MASS DUMPS INTO THE
UPPER LAKES ON BREEZY NW WINDS. IT`S POSSIBLE MAX TEMPS MAY ONLY BE
IN THE 50S OVER MUCH OF THE FCST AREA THU IF ANOTHER SHORTWAVE DOES
DROP INTO THE UPPER LAKES...RESULTING IN MOSTLY CLOUDY SKIES AND SCT
SHRA. IT APPEARS SFC HIGH WILL SETTLE INTO THE AREA THU NIGHT PER
CONSENSUS OF MEDIUM RANGE GUIDANCE. IF SO AND IF STRATOCU CLEARS
OUT...THERE WILL BE A WIDESPREAD FROST IN THE INTERIOR...ESPECIALLY
OVER THE W WHICH WILL BE CLOSER TO ARRIVING SFC HIGH PRES CENTER.
WITH SFC HIGH PRES LINGERING OVER THE AREA FRI...EXPECT A SUNNY BUT
COOL DAY...THOUGH NOT AS COOL AS THU. SOME FROST COULD OCCUR AGAIN
FRI NIGHT...THOUGH THIS TIME MORE LIKELY OVER THE E...CLOSER TO
DEPARTING SFC HIGH. WARMING TREND WILL BE UNDERWAY SAT UNDER
CONTINUED RETURN FLOW AS HIGH PRES MOVES TO THE E COAST. HIGH TEMPS
SAT SHOULD BE CLOSER TO NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 140 PM EDT SAT SEP 7 2013
LOW STRATUS AND FOG MOVED INTO ALL THREE TAF SITES OVER THE LAST
FEW HOURS. THIS IS DUE TO THE NORTHERLY FLOW BEHIND THE COLD FRONT
THAT MOVED THROUGH LAST NIGHT AND PUSHED THE LOW CLOUDS SOUTH
OFF LAKE SUPERIOR. EXPECT THESE CONDITIONS TO CONTINUE THROUGH MUCH
OF THE AFTERNOON...BUT DRIER AIR ASSOCIATED WITH HIGH PRESSURE NEAR
LAKE WINNIPEG HAS ALREADY BEEN SEEN ON VISIBLE SATELLITE SLIDING
SOUTH OVER NORTHERN LAKE SUPERIOR. IN ADDITION...THE
CEILINGS/VISIBILITIES HAVE ALREADY STARTED TO MOVE UPWARD AT KCMX
AND BASED OFF WEBCAMS IN THE KEWEENAW. THUS...SHOULD HAVE CONDITIONS
HEADING TO VFR FROM NORTH TO SOUTH BY LATE AFTERNOON INTO EARLY
EVENING. THIS DRY AIR WILL LEAD TO CLEAR SKIES AND WEAKENING WINDS
THROUGH THE REST OF THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 519 AM EDT SAT SEP 7 2013
A TROUGH WILL CONTINUE TO SINK SOUTH ACROSS THE UPPER GREAT LAKES
TODAY. BEHIND THE TROUGH...HIGH PRESSURE WILL BE ABLE TO SLIDE
IN...CROSSING LAKE SUPERIOR SUNDAY...BEFORE PUSHING ACROSS THE LOWER
GREAT LAKES SUNDAY NIGHT. ANY FOG THAT DEVELOPS WILL LIKELY SINK
SOUTH TODAY/TONIGHT AS DRIER AIR WORKS IN FROM THE N. A FEW GUSTS
NEAR 25KTS WILL BE POSSIBLE LATE TONIGHT THROUGH EARLY SUNDAY. LOW
PRESSURE ACROSS THE NORTHERN AND CENTRAL PLAINS SUNDAY NIGHT WILL
EDGE ACROSS THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. A BRIEF
RIDGE WILL FILTER IN TUESDAY NIGHT...OUT AHEAD OF A CENTRAL CANADIAN
LOW MOVING OVER HUDSON BAY ON WEDNESDAY. THIS LOW WILL BRING A
TROUGH TO LAKE SUPERIOR WEDNESDAY AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...KF
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1058 AM EDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1057 AM EDT SAT SEP 7 2013
TRICKY FORECAST FOR THE REST OF TODAY...AS THE COLD FRONT CONTINUES
TO SLIDE SOUTH ACROSS THE SOUTHEAST PART OF UPPER MICHIGAN. THE
THUNDERSTORMS ASSOCIATED WITH THIS FRONT HAVE NEARLY LEFT CWA IN
LAKE MICHIGAN. OTHER THAN A FEW SHOWERS REDEVELOPING OVER
DICKINSON/MENOMINEE COUNTIES THIS AFTERNOON...THE SHOWERS
ASSOCIATED WITH THE FRONT SHOULD BE DONE.
ATTENTION THEN TURNS TO THE CLOUDINESS OVER LAKE SUPERIOR. VISIBLE
SATELLITE SHOWS TWO CLOUD DECKS...WITH MID CLOUDS SHIFTING
EAST-SOUTHEAST AND A LOW STRATUS DECK DROPPING SOUTH TO
SOUTH-SOUTHWEST. THERE WAS SOME UNCERTAINTY ON IF THE CLOUDS WERE
FOG OR LOW STRATUS...AS WEBCAMS ALONG LAKE SUPERIOR IN THE KEWEENAW
AND EAST WEREN/T POINTING ONE WAY OR ANOTHER. BUT THE 1435Z OB FROM
KCMX HAS INDICATED IT IS MORE OF A LOW STRATUS WITH SOME FOG OR
DRIZZLE. THUS...WILL ADJUST THE FORECAST FOR LOCATIONS NEAR LAKE
SUPERIOR FOR MORE CLOUDINESS THIS AFTERNOON UNDER THE
NORTH-NORTHEAST WINDS. BASED OFF THE THICKNESS OF THE LOW CLOUDS ON
THE LATEST RAP RUNS...WILL ADD A MENTION OF DRIZZLE TO THE HIGHER
TERRAIN OF NORTH CENTRAL AND THE KEWEENAW DURING THE AFTERNOON.
THIS COOL FLOW OFF LAKE SUPERIOR WILL ALSO LEAD TO TEMPERATURES
FALLING THROUGH THE AFTERNOON FROM THE CURRENT VALUES IN THE LOWER
70S AND INTO THE MID-LOWER 60S TOWARDS EVENING. UPDATED GRIDS WILL
BE OUT SHORTLY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 519 AM EDT SAT SEP 7 2013
GENERALLY DECAYING SHOWERS AND THUNDERSTORMS HAVE BEEN THE
RULE...AND DESPITE ALL THE MOISTURE AROUND FOG HAS BEEN SLOW TO
MATERIALIZE ANYWHERE THAT HAD LESS THAN 0.25IN OF RAIN OVER THE PAST
24 HOURS. FOG OVER W AND E LAKE SUPERIOR TO PUSH S BEHIND THE COLD
FRONT SET UP FROM NW WI THROUGH THE KEWEENAW AND NE LAKE SUPERIOR.
THIS BOUNDARY WILL BE ENOUGH TO SPARK THE POTENTIAL OF ADDITIONAL
SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI LATE
THIS MORNING AND EARLY THIS AFTERNOON...BEFORE SIGNIFICANTLY
COOLER/DRIER AIR WORKS IN. MODEL TIMING ON THE COLD FRONT IS
REASONABLE...SLIPPING TO FAR S CENTRAL PORTIONS OF THE CWA BY 18Z.
EXPECT SLOWLY FALLING TEMPS THIS AFTERNOON OVER THE N AS A
RESULT...AS CLOUD COVER BEGINS TO DIMINISH. KEPT WITH THE COOL TEMPS
TONIGHT ON NNE FLOW AND 850MB TEMPS FALLING TO A CWA AVG 9C. PW
VALUES SHOULD FALL FROM AROUND 150 PERCENT OF NORMAL /1.5IN/ THIS
MORNING TO A 40-50 PERCENT OF NORMAL BY 12Z SUNDAY /0.35-0.4IN/.
LOWERED THE TRADITIONAL COOL SPOTS A BIT MORE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 505 AM EDT SAT SEP 7 2013
IN THE LONG TERM...PATTERN IN THE MEAN WILL CONTINUE TO FEATURE A NW
CANADA RIDGE AND ERN N AMERICA TROF. THIS WILL RESULT IN SHORTWAVES
PERIODICALLY DROPPING SE FROM THE NW RIDGE INTO THE ERN TROF. TWO
MORE SIGNIFICANT WAVES WILL BRING NOTABLE AMPLIFICATION OF THE ERN
TROF. THE FIRST WILL BE THIS WEEKEND AND THE SECOND WILL BE LATE IN
THE UPCOMING WEEK. THE SECOND AMPLIFICATION LOOKS LIKE IT WILL BRING
THE COOLEST AIR TO THE UPPER LAKES...POSSIBLY POSING A RISK OF THE
FIRST WIDESPREAD FROST OF THE SEASON LATE WEEK. BTWN THE 2 SURGES OF
COOL AIR...TEMPS WILL BE AT OR ABOVE NORMAL. UNDERNEATH THE LARGER
SCALE RIDGE/TROF PATTERN...MID LEVEL LOW CURRENTLY OVER ERN WA WILL
OPEN UP AND SHIFT GENERALLY E ROUGHLY ALONG THE U.S./CANADA
BORDER...AFFECTING THE UPPER LAKES MON/TUE. THIS SYSTEM SHOULD BRING
THE BEST CHANCE OF PCPN DURING THE LONG TERM PORTION OF THE FCST.
FARTHER DOWN THE ROAD...GUIDANCE SUGGESTS THE NW CANADA RIDGE WILL
BE REPLACED BY A TROF...RESULTING IN DOWNSTREAM HEIGHT RISES ACROSS
THE CNTRL CONUS. SO...A WARM PERIOD MAY BE SHAPING UP BEYOND THIS 7
DAY FCST.
BEGINNING SUN...ON THE BACKSIDE OF THE AMPLIFYING ERN TROF...
CANADIAN HIGH PRES WILL SETTLE SE OVER THE UPPER GREAT LAKES. ONLY
FCST CONCERN CONTINUES TO BE THE POTENTIAL FOR SOME MORNING LOW
CLOUDS OFF LAKE SUPERIOR IN UPSLOPE N/NE FLOW. THE NAM IS COOLEST IN
BRINGING 850-875MB TEMPS DOWN TO AROUND 5C ACROSS LAKE SUPERIOR AT
12Z SUN. OTHER GUIDANCE IS AROUND 2C WARMER. IF THE COOLER NAM IS
CORRECT...WATER TEMPS AS HIGH AS 16-18C OVER SRN LAKE SUPERIOR WILL
BE SUFFICIENT FOR STRATOCU OFF THE LAKE. SINCE LOW CLOUDS ARE
EVIDENT OVER HUDSON BAY INTO ADJACENT NRN MANITOBA/NRN ONTARIO AND
SINCE WIND FLOW AHEAD OF HIGH MAY TEND TO ADVECT SOME OF THIS
SHALLOW MOISTURE INTO THE AREA...OPTED TO RETAIN SOME CLOUD COVER
SUN MORNING NEAR LAKE SUPERIOR EVEN IN FAVORING GUIDANCE WARMER THAN
THE NAM. UPSLOPE CLOUDS SHOULDN`T STICK AROUND LONG UNDER
INCREASINGLY ANTICYCLONIC LOW-LEVEL FLOW...ADVECTION OF DRIER AIR
AND DAYTIME HEATING. FARTHER INLAND...MAY SEE A BLOSSOM OF SCT TO
PERHAPS BKN CU/STRATOCU FOR JUST A BRIEF TIME BEFORE DAYTIME HEATING
MIXES OUT LOW-LEVEL MOISTURE. THE AFTN HRS SHOULD FEATURE ABUNDANT
SUNSHINE ACROSS THE BOARD. TEMPS WILL BE ON THE COOL SIDE OF NORMAL
DESPITE THE SUNSHINE. MIXING TO THE INVERSION BASE ON FCST SOUNDINGS
YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING INFLUENCE OF THE
GREAT LAKES.
SUN NIGHT...MIDLEVEL LOW CURRENTLY OVER ERN WA WILL HAVE OPENED UP
AND WILL REACH SRN SASKATCHEWAN/ERN MT BY 12Z MON. IN RESPONSE...
DEVELOPING LOW-LEVEL JET WILL SHIFT ACROSS THE DAKOTAS INTO MN
DURING THE NIGHT. THE ECMWF CONTINUES TO BE THE FASTEST SPREADING
PCPN INTO UPPER MI SUN NIGHT IN ASSOCIATION WITH A LEAD MINOR
SHORTWAVE MOVING INTO THE UPPER LAKES. THE UKMET HAS NOW FOLLOWED
SUIT. THE GFS HAS PCPN REACHING THE FAR W OVERNIGHT. MEANWHILE...THE
NAM/GEM MAINTAIN STRONGER SFC HIGH PRES RIDGING BACK INTO THE UPPER
LAKES AND THUS KEEP PCPN W OF UPPER MI THRU 12Z MON. FOR NOW...PLAN
TO MAINTAIN CONTINUITY WITH THE LAST FEW FCST CYCLES AND WILL ONLY
BRING SCHC POPS INTO THE FAR W OVERNIGHT...SIMILAR TO THE GFS WHICH
REPRESENTS A GOOD COMPROMISE BTWN THE ECMWF/UKMET AND GEM/NAM.
OTHERWISE...SOUTHERLY RETURN FLOW OF WARMER/MOISTER AIR AND AN
INCREASE IN CLOUDS WILL RESULT IN A WARMER NIGHT MOST AREAS...
ESPECIALLY OVER THE W WHERE GRADIENT WILL BE TIGHTENING FIRST AND
WHERE CLOUDS WILL ARRIVE EARLIEST. LINGERING DRY AIR MASS IN THE
EVENING COMBINED WITH INITIALLY CLEAR SKIES AND LIGHT/CALM WIND OVER
THE E MAY ALLOW TEMPS AT TRADITIONAL INTERIOR COLD SPOTS TO FALL
INTO THE LWR 40S.
MON/TUE...MAIN SHORTWAVE WILL CONTINUE TO TRACK E...PASSING ACROSS
THE UPPER LAKES MON NIGHT/TUE. WHILE TIMING OF FEATURE HAS
IMPROVED...TRACK OF ASSOCIATED SFC LOW REMAINS MORE UNCERTAIN.
THE ECMWF HAS TRENDED S AND HAS SFC LOW TRACKING ACROSS UPPER MI...
NOT TOO DIFFERENT FROM THE NAM. ONLY SCNTRL AND ERN UPPER MI MAY
SLIP INTO THE WARM SECTOR MON NIGHT. END RESULT WOULD PROBABLY BE
FAIRLY WIDESPREAD SHRA/TSRA ACTIVITY ACROSS THE FCST AREA MON...
ESPECIALLY NRN PORTIONS. THE GFS/GEM ARE FARTHER N (GEM HAS BEEN ALL
ALONG) AND HAVE SFC LOW TRACKING OVER OR JUST N OF LAKE SUPERIOR.
RESULT WOULD BE SHRA/TSRA ACTIVITY N OF WARM FRONT BEING SHIFTED
FARTHER N...PERHAPS MOSTLY N OF UPPER MI MON/MON NIGHT. WITH THE
ECMWF NORMALLY PROVIDING BETTER GUIDANCE AND WITH 2 CONSECUTIVE RUNS
NOW SHOWING THE FARTHER S TRACK...HEDGED FCST SLIGHTLY IN THAT
DIRECTION WHICH RESULTED IN INCREASING POPS/QPF A BIT ACROSS THE N
MON/MON NIGHT. EFFECTIVE SHEAR MON LOOKS BE ON THE ORDER OF
30-40KT...SUPPORTING THE POTENTIAL OF STRONG TO SVR STORMS...BUT
MUCH WILL DEPEND ON THE MAGNITUDE OF INFLOW INSTABILITY FOR THE
ELEVATED STORMS. EVEN THE GFS WITH ITS FARTHER N SFC LOW TRACK IS
SLOW TO BRING SUFFICIENT INSTABILITY N FOR STRONG/SVR STORMS MON.
BETTER POTENTIAL OF SVR STORMS SHOULD BE MON NIGHT AS INSTABILITY
AXIS SHIFTS INTO THE UPPER LAKES. HOWEVER...IF WARM FRONT LIFTS N OF
THE AREA...EXPECTED ARRIVAL OF COLD FRONT LATE NIGHT INTO TUE
MORNING WOULD BE MORE IN SYNC WITH DIURNAL MIN...SUGGESTING A
DIMINISHED SVR THREAT. IF WARM FRONT ONLY LIFTS INTO UPPER MI...THEN
THERE WOULD BE THE POTENTIAL FOR ELEVATED SVR STORMS N OF FRONT MON
NIGHT. AT LEAST WITH SHORTWAVE RAPIDLY WEAKENING AS IT MOVES ACROSS
THE UPPER LAKES...THERE DOES NOT APPEAR TO BE A POTENTIAL FOR
WIDESPREAD SVR STORMS. LATEST SPC OUTLOOK ONLY HAS PORTIONS OF UPPER
MI IN A 5 PCT RISK WHICH APPEARS REASONABLE AT THIS TIME. ON TUE...
SHRA/TSRA CHANCES SHOULD BE MOSTLY CONFINED TO THE ERN FCST AREA AS
SFC LOW/COLD FRONT WILL STILL NEED TO PASS THRU THAT AREA.
HEADING INTO WED/THU...THE ECMWF HAS CONTINUED TO BACK OFF ON ITS
FARTHER W AND MUCH MORE SHARPLY DIGGING SHORTWAVE INTO THE UPPER
MISSISSIPPI VALLEY AND GREAT LAKES. NOW...MEDIUM RANGE GUIDANCE IS
GENERALLY WELL CLUSTERED WITH THE TROF AMPLIFICATION OCCURRING THRU
THE GREAT LAKES AND THEN INTO NEW ENGLAND LATE WEEK. WITH MUCH OF
THE DEEP MOISTURE SWEPT OUT OF THE AREA BY THE PRIOR SHORTWAVE...
NOTHING MORE THAN LOW CHC POPS APPEAR WARRANTED WED AS COLD FRONT
DROPS THRU THE UPPER LAKES. SHRA CHANCES MAY LINGER THRU THU WITH
HINTS OF ANOTHER WAVE DROPPING ACROSS THE AREA INTO THE AMPLIFYING
TROF. THU WILL FEEL LIKE AUTUMN AS COOL AIR MASS DUMPS INTO THE
UPPER LAKES ON BREEZY NW WINDS. IT`S POSSIBLE MAX TEMPS MAY ONLY BE
IN THE 50S OVER MUCH OF THE FCST AREA THU IF ANOTHER SHORTWAVE DOES
DROP INTO THE UPPER LAKES...RESULTING IN MOSTLY CLOUDY SKIES AND SCT
SHRA. IT APPEARS SFC HIGH WILL SETTLE INTO THE AREA THU NIGHT PER
CONSENSUS OF MEDIUM RANGE GUIDANCE. IF SO AND IF STRATOCU CLEARS
OUT...THERE WILL BE A WIDESPREAD FROST IN THE INTERIOR...ESPECIALLY
OVER THE W WHICH WILL BE CLOSER TO ARRIVING SFC HIGH PRES CENTER.
WITH SFC HIGH PRES LINGERING OVER THE AREA FRI...EXPECT A SUNNY BUT
COOL DAY...THOUGH NOT AS COOL AS THU. SOME FROST COULD OCCUR AGAIN
FRI NIGHT...THOUGH THIS TIME MORE LIKELY OVER THE E...CLOSER TO
DEPARTING SFC HIGH. WARMING TREND WILL BE UNDERWAY SAT UNDER
CONTINUED RETURN FLOW AS HIGH PRES MOVES TO THE E COAST. HIGH TEMPS
SAT SHOULD BE CLOSER TO NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 757 AM EDT SAT SEP 7 2013
PLENTY OF LOW LEVEL MOISTURE HAS RESULTED IN IFR-MVFR VIS AT SEVERAL
UPSTREAM AND DOWNSTREAM LOCATIONS. HOWEVER CMX...IWD...AND SAW
REMAINED MAINLY FOG FREE AS CLOUDS LINGERED AND SFC TEMPERATURES
REMAINED A LITTLE TOO WARM. WILL CONTINUE TO TRACK THE EXITING COLD
FRONT AND CONTINUED POTENTIAL FOR SCT-ISO SHOWERS AND TS THROUGH
EARLY AFTERNOON. HAVE KEPT THE MENTION OF SHOWERS OR TS OUT OF ALL
SITES /EXCLUDING VCTS AT CMX INITIALLY AS A CLUSTER OF TS PUSH
ACROSS THE KEWEENAW PENINSULA/. WITH DRY HIGH PRESSURE SLOWLY
PUSHING IN FROM THE NW THIS AFTERNOON EVENING...DO NOT EXPECT ANY
FOG TO DEVELOP TONIGHT. EXPECT WINDS AROUND 10KTS OR LESS
OVERNIGHT...UNDER A MOSTLY CLEAR SKY.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 519 AM EDT SAT SEP 7 2013
A TROUGH WILL CONTINUE TO SINK SOUTH ACROSS THE UPPER GREAT LAKES
TODAY. BEHIND THE TROUGH...HIGH PRESSURE WILL BE ABLE TO SLIDE
IN...CROSSING LAKE SUPERIOR SUNDAY...BEFORE PUSHING ACROSS THE LOWER
GREAT LAKES SUNDAY NIGHT. ANY FOG THAT DEVELOPS WILL LIKELY SINK
SOUTH TODAY/TONIGHT AS DRIER AIR WORKS IN FROM THE N. A FEW GUSTS
NEAR 25KTS WILL BE POSSIBLE LATE TONIGHT THROUGH EARLY SUNDAY. LOW
PRESSURE ACROSS THE NORTHERN AND CENTRAL PLAINS SUNDAY NIGHT WILL
EDGE ACROSS THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. A BRIEF
RIDGE WILL FILTER IN TUESDAY NIGHT...OUT AHEAD OF A CENTRAL CANADIAN
LOW MOVING OVER HUDSON BAY ON WEDNESDAY. THIS LOW WILL BRING A
TROUGH TO LAKE SUPERIOR WEDNESDAY AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...KF
LONG TERM...ROLFSON
AVIATION...KF
MARINE...KF
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
915 PM CDT Sun Sep 8 2013
.UPDATE:
Issued at 856 PM CDT Sun Sep 8 2013
Scattered showers that were over the eastern Ozark counties
earlier this evening rotated south around the upper high that is
currently centered over northwest Missouri. The RAP/HRRR still
indicates the potential for the redevelopment of thunderstorms
along and east of the Mississippi river between 06-12Z tonight, so
have concentrated slight chances of rain the rest of the night in
these locations. This is where the HRRR develops N-S band of
storms in an area of 925-850mb moisture convergence seen on the
RAP. Some fog will also be possible tonight where skies clear
with light winds, particularly where heavy rain fell earlier
today.
Britt
&&
.SHORT TERM: (Through Late Tonight)
Issued at 335 PM CDT Sun Sep 8 2013
The primary forecast issue for tonight is precipitation chances.
Unfortunately, this is not a straightforward forecast. The cold
front which was supposed to have moved through the CWA last night
has instead stalled near the MO/IA border, and the MCS which moved
through the CWA earlier today has also changed the situation with
respect to precipitation chances for tonight.
First, the aforementioned MCS produced several hours of steady
rainfall across most of the CWA, significantly moistening the lower
levels of the atmosphere. Second, differential heating between the
clear skies over western MO and the MCS-generated clouds over
eastern MO has produced a surface boundary that resembles a warm
front, including surface convergence noted on afternoon METARs. This
feature stretched from NW MO to near KCOU and then southward into
the Ozarks, and it is distinct from the true synoptic warm front
which was located from the Dakotas through IA and MN and then into
northern IL. Third, a persistent cluster of showers and
thunderstorms has already developed over extreme northwestern MO.
Model forecasts suggest that the H85 LLJ will interact with the
synoptic warm front well to our north tonight, and this scenario
still looks very reasonable. However, our concern is whether
additional thunderstorms will develop farther south, mainly across
parts of MO. H85 winds to the southeast of the main LLJ core are
forecast to veer with time and would impinge on the convergence zone
(remnant of the differential heating boundary), if it still exists,
and the overnight MUCAPE axis is forecast to extend into the LSX
CWA. Admittedly, there are a lot of "ifs" and "mights" when it comes
to thunderstorm chances tonight, but there`s enough substance here
to warrant slight chance PoPs until the atmosphere shows its hand
over the next several hours.
Kanofsky
.LONG TERM: (Monday through Next Sunday)
Issued at 335 PM CDT Sun Sep 8 2013
12z guidance continues to support the thinking that hot September
weather will dominate the region on Monday and Tuesday as the upper
ridge shifts east into the Ohio valley. This mornings UA data
indicated 850 mb temps aoa 24C over a large section of the central
plains, and this air should advect into the mid-Mississippi valley
with time. Some residual cloudiness may hinder the warm up just a
bit over our far se counties, but with this thermal ridge punching
across the n half of our CWA temps should easily be in the mid-upper
90s both Monday and Tuesday. It`s not out of the question that some
areas will approach the century mark due to deep mixing in this hot
airmass with a pronounced westerly component to the low level flow
and strong sunshine. And, (in spite of todays rain) dry soil and
vegetation remains in many areas, and especially in those locations
north of highway 36 where little if any rain fell today.
Aforementioned mixing should allow a fairly substantial drop in
dewpoints during the afternoon hours, especially in the hottest air
over n sections of the CWA. Calculated hourly apparent temperatures
based on this thinking is still capping the HI at around 100 in some
spots, so no heat headlines needed at this time.
As far as rain potential is concerned, if storms do form
overnight believe that most of them will be drifting out of the
area by morning. Based on development and timing its possible
later shifts may have to hang onto some pops for early Monday
morning, but due to considerable uncertainty on location, timing,
and even occurrence of overnight convection have maintained a
rain-free forecast for Monday morning. Another nagging concern is
the spotty rainfall that the NAM, GFS, and even the ECMWF have
been trying to generate over our southeast counties over the past
few days. 12z runs are also hinting at this, but are a bit more
sporadic with this than earlier solutions. The only mechanism I
can see for this is ams-type diurnal convection, perhaps aided by
a bit of orographic lift into the eastern Ozarks. However,
directly beneath an upper ridge seems like an odd place for this
to occur (current activity going up near STJ notwithstanding). At
this point will maintain dry forecast, and let mid shift take
another look at short range guidance to determine if the inclusion
of POPs is warranted.
Latest medium range guidance also hasn`t changed much in their
handling of cold front and its southward push across the mid-
Mississippi valley in the Wednesday night-Thursday time frame as
upper trof begins to develop over the eastern CONUS. Have kept
POPs in the chance category for now due to rather weak dynamics
and what appears to be limited convergence along the front.
Since fropa won`t occur in our area until Wednesday night have
kept Wednesdays temps aoa guidance in all but northern sections
of the CWA where some afternoon clouds and convection will be
possible. Going temp trends for remainder of the extended (which
reflect continued cooling into Saturday) still look reasonable as
large Canadian high builds into the eastern U.S.
Truett
&&
.AVIATION: (For the 00z TAFs through 00z Monday Evening)
Issued at 639 PM CDT Sun Sep 8 2013
Weak warm front is drifting northeast through northern
Missouri/southern Iowa. Winds have come back around to the south-
southeast across the area...and I expect this south-southeast flow
to continue for the rest of the night. Big question is still
when/if rain will affect the area tonight. think the best chances
after the showers over the eastern Ozarks die this evening, will
be relatively close to the front across northern Missouri and
western Illinois. Current indications are that any showers that
form will be isolated to widely scattered with no organization.
could see some rumbles of thunder, but again with no organization.
VFR flight conditions will prevail outside of any showers that
form. The exception may be terminals in river valleys where some
MVFR fog is expected...especially where clouds kept temperatures
cooler for much of the day such as KSUS and KCPS.
Expect VFR flight conditions and strengthening southwest flow on
Monday.
Specifics for KSTL:
Expecting VFR flight conditions to prevail at Lambert tonight.
There is a chance there may be some isolated showers late
tonight...but think the primary threat for any precip will be
north and east of the terminal. Expect some fog in the Missouri
River valley west of the terminal late...but no fog is expected at
the terminal. VFR flight conditions will prevail on Monday with an
increasing southwest wind.
Carney
&&
.CLIMATE:
ISSUED AT 306 PM CDT SAT SEP 7 2013
RECORD HIGHS:
SEPT 9 SEPT 10
STL 101/1925 98/1983
COU 99/1925 99/1938
UIN 100/1945 100/1933
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BILLINGS MT
306 PM MDT SAT SEP 7 2013
.SHORT TERM...VALID FOR SUN AND MON...
INGREDIENTS ARE IN PLACE ACROSS THE REGION FOR A BUSY AFTERNOON
AND NIGHT. UPPER TROUGH OVER WASHINGTON STATE SLOWLY MOVING
EASTWARD. LOW LEVEL JET OVER EAST HAS BROUGHT UP AN ABUNDANT
AMOUNT OF MOISTURE ACROSS THE EASTERN SECTIONS OF MONTANA AND
NEARBY AREAS. MONSOONAL MOISTURE IS EXPECTED TO STREAM ACROSS THIS
SAME AREA. PRECIPITABLE WATER LEVELS UP AROUND 1.50 INCHES...WHICH
IS HIGHLY UNUSUAL FOR THIS TIME OF YEAR...WILL LIKELY LEAD TO
THUNDERSTORMS WITH VERY HEAVY RAINFALL. WE HAVE ALSO SEEN SOME
TRAINING CELLS OVER CUSTER COUNTY ALREADY TODAY. THUS...THE FLASH
FLOOD WATCH WILL REMAIN IN PLACE THROUGH 6AM. THE HRRR MODEL
DEVELOPS TWO WAVES OF CONVECTIVE ACTIVITY...PRIMARILY HITTING
AREAS FROM BIG HORN COUNTY NORTH AND EAST...AND THE LAST WAVE
CARRIES WELL INTO THE NIGHT OUT EAST.
DUE TO INSTABILITY FACTORS AND SHEAR PROFILES...WE COULD ALSO SEE
SOME HAIL AND DAMAGING WIND...THOUGH AT THIS TIME I FEEL
TORRENTIAL RAINFALL IS MORE OF A THREAT. THE SHEAR PROFILE AND
OVERALL PATTERN DOES ALSO SUPPORT THE SLIGHT CHANCE OF AN ISOLATED
TORNADO IN THE EASTERN COUNTIES...THOUGH WOULD LIKE TO SEE SHEAR
JUST A BIT STRONGER...LESS INITIAL CLOUD COVER AND GREATER
INSTABILITY. NEVERTHELESS...WE WILL BE MONITORING STORMS CLOSELY
FOR DEEP ROTATION...ESPECIALLY FROM MILES CITY TO BROADUS
EASTWARD.
AS STORMS DIMINISH IN THE EAST LATE TONIGHT...UPPER TROUGH BEGINS
TO SWING THROUGH NORTH/CENTRAL MONTANA IN THE MORNING. BEST
MOISTURE AND SHEAR PROFILES WILL BE LOCATED FURTHER EAST...BUT
LIFT WILL BE MUCH GREATER ACROSS THE REGION WITH GOOD Q VECTOR
FORCING. HEAVY RAIN IS STILL A GOOD BET TOMORROW WITH SOME
STORMS...AND MAYBE LOTS OF SMALL HAIL OR GROUPEL. BT
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
SEASONABLY WARM WEATHER IS EXPECTED NEXT WEEK...WITH AN INCREASING
CHANCE OF CONVECTION BY FRI AND SAT WHEN THE 12 UTC GUIDANCE SHOWS
ANOTHER SURGE OF MONSOONAL MOISTURE ARRIVING. AN AMPLIFIED 500-HPA
RIDGE WILL BECOME ESTABLISHED ACROSS THE REGION ONCE AGAIN BY MID-
WEEK WITH ABOVE-NORMAL HEIGHTS FOR THIS TIME OF THE YEAR. ITS AXIS
APPEARS ORIENTED MORE NORTHWEST-SOUTHEAST THAN LAST WEEK/S VERSION
OF A LATE-SEASON RIDGE THOUGH...WHICH WILL LIKELY HELP MAINTAIN AN
EASTERLY LOW-LEVEL FLOW AND A SOMEWHAT COOLER AIR MASS IN SOUTHERN
MT AND NORTHERN WY THAN WHAT WE HAVE EXPERIENCED RECENTLY. BY LATE
IN THE WEEK...GUIDANCE SUGGESTS SHORT WAVE ENERGY WILL LIFT ACROSS
THE AREA AND LOWER THE 500-HPA HEIGHTS AS PRECIPITABLE WATER AGAIN
RISES ABOVE AN INCH. THE RESULT SHOULD BE AT LEAST ISOLATED SHOWER
AND STORM ACTIVITY...AND INCREASING CLOUDS TO HOLD BACK HIGHS SOME
MORE. IF TRENDS IN THE 12 UTC GUIDANCE HOLD TRUE WITH LATER CYCLES
THEN WE MAY NEED TO LOWER HIGHS A BIT THROUGH THE PERIOD AND RAISE
POPS A BIT BY FRI AND SAT. SCHULTZ
&&
.AVIATION...
THUNDERSTORMS WILL AFFECT THE AREA THROUGH THIS EVENING...WITH THE
HIGHEST PROBABILITIES OF STORMS FROM AROUND KSHR TO KMLS AND KBHK.
IFR OR POSSIBLY EVEN LIFR CONDITIONS IN HEAVY RAIN ARE EXPECTED IN
THE MOST INTENSE STORMS...WITH A THREAT OF LARGE HAIL AND DAMAGING
WINDS TOO. THE ACTIVITY SHOULD SLOWLY DIMINISH BY LATE NIGHT...BUT
LOW CEILINGS MIGHT FORM IN ITS WAKE BY SUNDAY MORNING. SCHULTZ
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 060/081 057/079 054/084 055/085 058/088 060/088 057/088
45/T 50/B 00/U 00/U 00/U 12/T 22/T
LVM 053/080 048/077 046/084 046/085 051/087 052/090 054/090
34/T 31/U 00/U 00/U 02/T 23/T 32/T
HDN 059/083 055/081 052/085 053/087 057/090 058/089 059/090
56/T 51/B 00/U 00/U 00/U 11/U 12/T
MLS 063/082 059/080 055/084 055/085 057/086 060/086 058/088
56/T 62/W 10/U 00/U 00/U 11/U 11/U
4BQ 062/084 058/081 052/084 054/086 057/086 058/086 059/090
65/T 52/W 00/U 00/U 00/U 12/T 22/T
BHK 061/081 057/077 053/080 054/081 054/080 056/081 055/081
76/T 72/T 11/U 10/U 00/U 11/U 12/T
SHR 058/082 053/077 047/083 050/085 053/089 055/087 053/087
45/T 42/W 00/U 00/U 00/U 12/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES
29>33-35>38-57-58.
WY...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES
98-99.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
143 PM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR IMAGERY EARLY THIS AFTERNOON SHOWING A LARGE AREA OF SHOWERS
FROM SOUTHERN ONTARIO EAST ACROSS THE NIAGARA FRONTIER INTO CENTRAL
NY. THIS WILL CONTINUE TO DRIFT SLOWLY ESE ACROSS THE AREA THIS
AFTERNOON WITH OCCASIONAL SHOWERS. THE SOUTHERN TIER WILL ESCAPE
MUCH OF THIS THROUGH LATE AFTERNOON...ESPECIALLY CLOSER TO THE PA
STATE LINE. THE SAINT LAWRENCE VALLEY WILL ALSO HAVE PLENTY OF DRY
TIME WITH JUST A FEW BRIEF SHOWERS.
WATER VAPOR IMAGERY AND 500MB ANALYSIS SHOWS SEVERAL MID LEVEL
SHORTWAVES MOVING THROUGH THE MEAN NORTHWEST FLOW ALOFT...WITH A
SUPPORTING MID LEVEL SPEED MAX NOTED IN OBJECTIVE RUC ANALYSIS FROM
NORTHERN LAKE HURON TO LAKE ONTARIO. THESE FEATURES ARE AIDING IN
LARGE SCALE ASCENT AND CONVERGENCE. SEASONABLY STRONG LOW/MID LEVEL
WARM ADVECTION AND ISENTROPIC UPGLIDE ARE ALSO FOUND TO THE
NORTHEAST OF A WARM FRONT ANALYZED NEAR LAKE HURON AT 12Z...AND IS
LIKELY PROVIDING THE NECESSARY CONCENTRATED ASCENT TO SUPPORT THE
AREA OF STEADY RAIN OVER LAKE ONTARIO.
WITH THICK CLOUD AND AN EARLIER ARRIVAL OF SHOWERS...TEMPERATURES
WILL STRUGGLE AND STAY IN THE MID TO UPPER 60S IN MOST AREAS. THE
ONLY EXCEPTION WILL BE ACROSS THE SOUTHERN TIER WHERE PLENTY OF DRY
TIME WILL STILL BE FOUND...WITH TEMPERATURES REACHING THE MID 70S IN
THE VALLEYS THERE.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AN AREA OF SHOWERS ACROSS MUCH OF UPSTATE NY EARLY THIS AFTERNOON
WILL CONTINUE THROUGH THE FIRST HALF OF TONIGHT AS A COLD FRONT
PUSHES SOUTH ACROSS THE AREA. CONDITIONS WILL STAY VFR MUCH OF THE
TIME THROUGH THIS EVENING AS THE LOW LEVELS REMAIN UNSATURATED...
ALTHOUGH SOME BRIEF DIPS TO MVFR/IFR VSBY ARE POSSIBLE IN THE
HEAVIEST SHOWERS.
FOLLOWING THE COLD FRONTAL PASSAGE IN THE 05Z-07Z TIME FRAME...
SHOWERS WILL TAPER OFF FROM NORTH TO SOUTH. A FEW LINGERING LIGHT
SHOWERS MAY PERSIST THROUGH SUNDAY MORNING ACROSS HIGHER TERRAIN DUE
TO UPSLOPE FLOW...AND SOUTHEAST OF LAKE ONTARIO DUE TO SOME WEAK
LAKE EFFECT AS COOLER AIR CROSSES THE LAKE. OF MORE IMPORTANCE...A
PERIOD OF LOWER CIGS IS EXPECTED FOLLOWING THE COLD FRONTAL PASSAGE
AS EXTENSIVE LOW LEVEL MOISTURE BECOMES TRAPPED UNDER A STEEP
FRONTAL INVERSION. THIS WILL BRING AREAS OF IFR CIGS LATER TONIGHT
THROUGH SUNDAY MORNING. THE LOW CIGS WILL SCATTER OUT FROM NORTH TO
SOUTH ON SUNDAY AS DRIER AIR AND SUBSIDENCE BUILD SOUTH OUT OF
ONTARIO WITH HIGH PRESSURE BUILDING BACK INTO THE GREAT LAKES.
OUTLOOK...
MONDAY AND TUESDAY...MAINLY VFR.
WEDNESDAY...MVFR/VFR. A CHANCE OF THUNDERSTORMS.
THURSDAY...MVFR/VFR WITH A CHANCE OF SHOWERS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO EASTERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. SMALL CRAFT ADVISORY CONDITIONS ARE ALSO LIKELY AGAIN
ON LAKE ERIE MAINLY FROM DUNKIRK TO THE PA STATE LINE AS NORTH TO
NORTHEAST WINDS INCREASE BEHIND THE COLD FRONT.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LEZ041.
SMALL CRAFT ADVISORY UNTIL 4 PM EDT SUNDAY FOR LEZ040.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
LEZ020.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...HITCHCOCK
MARINE...APFFEL/HITCHCOCK
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1043 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR IMAGERY SHOWING AN EXTENSIVE AREA OF STEADY RAIN AND A FEW
EMBEDDED LIGHTNING STRIKES OVER SOUTHERN ONTARIO AND LAKE ONTARIO
THIS MORNING. THIS AREA OF RAIN IS FASTER AND FARTHER SOUTH THAN ANY
MODEL GUIDANCE...SO TIMING AND PLACEMENT OF RAIN HAS BEEN ADJUSTED
FOR TODAY BY EXTRAPOLATION OF RECENT RADAR AND SATELLITE TRENDS.
HAVE BROUGHT THE STEADIER RAIN INTO THE COUNTIES ALONG AND SOUTHEAST
OF THE LAKE ONTARIO SHORE...WITH A FAIRLY SHARP CUTOFF TO LOWER
CHANCE POPS ACROSS THE SOUTHERN PORTION OF THE AREA AND ALSO IN THE
SAINT LAWRENCE VALLEY.
WATER VAPOR IMAGERY AND 500MB ANALYSIS SHOWS SEVERAL MID LEVEL
SHORTWAVES MOVING THROUGH THE MEAN NORTHWEST FLOW ALOFT...WITH A
SUPPORTING MID LEVEL SPEED MAX NOTED IN OBJECTIVE RUC ANALYSIS FROM
NORTHERN LAKE HURON TO LAKE ONTARIO. THESE FEATURES ARE AIDING IN
LARGE SCALE ASCENT AND CONVERGENCE. SEASONABLY STRONG LOW/MID LEVEL
WARM ADVECTION AND ISENTROPIC UPGLIDE ARE ALSO FOUND TO THE
NORTHEAST OF A WARM FRONT ANALYZED NEAR LAKE HURON AT 12Z...AND IS
LIKELY PROVIDING THE NECESSARY CONCENTRATED ASCENT TO SUPPORT THE
AREA OF STEADY RAIN OVER LAKE ONTARIO.
WITH THICK CLOUD AND AN EARLIER ARRIVAL OF SHOWERS...TEMPERATURES
WILL STRUGGLE TO REACH 70 TODAY IN MANY AREAS. THE ONLY EXCEPTION
WILL BE ACROSS THE SOUTHERN TIER WHERE PLENTY OF DRY TIME WILL STILL
BE FOUND...WITH TEMPERATURES REACHING THE MID 70S IN THE VALLEYS
THERE.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS
LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO
BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY
WITH THIS GIVEN THE DRY LOW LEVELS NOTED ON THE 12Z KBUF SOUNDING.
ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING ALONG THE MAIN
COLD FRONT. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR
CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO EASTERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. SMALL CRAFT ADVISORY CONDITIONS ARE ALSO LIKELY AGAIN
ON LAKE ERIE MAINLY FROM DUNKIRK TO THE PA STATE LINE AS NORTH TO
NORTHEAST WINDS INCREASE BEHIND THE COLD FRONT.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LEZ041.
SMALL CRAFT ADVISORY UNTIL 4 PM EDT SUNDAY FOR LEZ040.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
LEZ020.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL/HITCHCOCK
MARINE...APFFEL/HITCHCOCK
AREA FORECAST DISCUSSION
NWS BUFFALO NY
751 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SKIES WILL BE MOSTLY CLOUDY ACROSS THE REGION THIS MORNING.
DESPITE THE CLOUD COVER...EXPECT JUST A FEW SPRINKLES THIS
MORNING...WITH THE STEADIER SHOWERS HOLDING OFF UNTIL HE
AFTERNOON HOURS.
AN AREA OF SHOWERS NW OF LAKE ONTARIO AT DAYBREAK WILL CONTINUE TO
TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM LINK
THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER
LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A
DIFFLUENT UPPER LEVEL FLOW. WITH THE FEATURE ON RADAR WE HAVE
FAIRLY HIGH CONFIDENCE THAT IT WILL CONTINUE TO TRACK WITH THE 500
MB FLOW. THE GFS HAS CONSISTENTLY HAD THE BEST HANDLE ON
THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE ADVECTION OF A
FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO ENTER N OF
I-90 EARLY THIS AFTERNOON...WITH SHOWERS THEN SLIDING ESE INTO
THE FINGER LAKES AND EAST OF LAKE ONTARIO LATE AFTERNOON. WITH A
FEW LIGHTNING STRIKES UPSTREAM...CANNOT RULE OUT AN ISOLATED
THUNDERSTORM AS THE SHOWERS MOVE ACROSS LAKE ONTARIO. THE
SOUTHERN TIER SHOULD STAY DRY.
HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY
CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF
LAKE ONTARIO. ALSO...TEMPERATURES WILL DROP AS THE SHOWERS MOVE
IN...SO HIGHS MAY COME LATE MORNING IN SOME SPOTS. A DECENT SW
BREEZE WILL DEVELOP OFF LAKE ERIE FROM BUFFALO TO NIAGARA FALLS.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT 12Z...TAF SITES SHOULD START OFF VFR. AN INITIAL WAVE OF
SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS LAKE ONTARIO THIS
AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO BUF/IAG/ROC/ART.
CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY WITH THIS. THEN
ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING. THE MOST
SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR CIGS WHICH ARE
LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS
WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT
AND MONDAY...AS HIGH PRESSURE BUILDS IN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LEZ020-041.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL
MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
435 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SUNSHINE MAY BRIEFLY SNEAK IN EARLY THIS MORNING...BUT HIGH CLOUDS
WILL MOVE IN QUICKLY FROM NW-SE. DESPITE THE CLOUDS...THE REGION
SHOULD STAY MOSTLY DRY THROUGH THE MORNING HOURS OUTSIDE OF A FEW
SPRINKLES NORTH OF THE THRU-WAY.
AN AREA OF SHOWERS ACROSS LAKE HURON EARLY THIS MORNING WILL
CONTINUE TO TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM
LINK THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER
LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A
DIFFLUENT UPPER LEVEL FLOW. PREVIOUS MODEL GUIDANCE DIFFERED ON THE
EXTENT OF SHOWERS WITH THIS FEATURE...BUT NOW THAT RADAR SHOWS IT
HAS DEVELOPED WE CAN HAVE FAIRLY HIGH CONFIDENCE THAT IT WILL
CONTINUE TO TRACK WITH THE 500 MB FLOW. THE GFS HAS CONSISTENTLY HAD
THE BEST HANDLE ON THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE
ADVECTION OF A FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO
ENTER N OF I-90 THIS AFTERNOON...WITH THESE WEAKENING LATE AFTERNOON
AS THE SHOWERS SLIDE ESE INTO THE FINGER LAKES AND EAST OF LAKE
ONTARIO. THE SOUTHERN TIER SHOULD STAY DRY.
HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY
CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF
LAKE ONTARIO. A DECENT SW BREEZE WILL DEVELOP OFF LAKE ERIE FROM
BUFFALO TO NIAGARA FALLS.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THIS MORNING WITH
MAINLY MID AND HIGH CLOUDS. THE EXCEPTION IS AT JHW...WHERE VSBY
WILL VARY IN GROUND FOG...WHICH SHOULD DISSIPATE AROUND 12Z.
AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS
LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO
BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR
CATEGORY WITH THIS. THEN ANOTHER ROUND OF SHOWERS WILL DROP N-S
THIS EVENING. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE
MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT
LATE TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS
WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT
AND MONDAY...AS HIGH PRESSURE BUILDS IN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LEZ020-041.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL
MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
352 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SUNSHINE MAY BRIEFLY SNEAK IN EARLY THIS MORNING...BUT HIGH CLOUDS
WILL MOVE IN QUICKLY FROM NW-SE. DESPITE THE CLOUDS...THE REGION
SHOULD STAY MOSTLY DRY THROUGH THE MORNING HOURS OUTSIDE OF A FEW
SPRINKLES NORTH OF THE THRU-WAY.
AN AREA OF SHOWERS ACROSS LAKE HURON EARLY THIS MORNING WILL
CONTINUE TO TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM
LINK THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER
LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A
DIFFLUENT UPPER LEVEL FLOW. PREVIOUS MODEL GUIDANCE DIFFERED ON THE
EXTENT OF SHOWERS WITH THIS FEATURE...BUT NOW THAT RADAR SHOWS IT
HAS DEVELOPED WE CAN HAVE FAIRLY HIGH CONFIDENCE THAT IT WILL
CONTINUE TO TRACK WITH THE 500 MB FLOW. THE GFS HAS CONSISTENTLY HAD
THE BEST HANDLE ON THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE
ADVECTION OF A FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO
ENTER N OF I-90 THIS AFTERNOON...WITH THESE WEAKENING LATE AFTERNOON
AS THE SHOWERS SLIDE ESE INTO THE FINGER LAKES AND EAST OF LAKE
ONTARIO. THE SOUTHERN TIER SHOULD STAY DRY.
HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY
CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF
LAKE ONTARIO. A DECENT SW BREEZE WILL DEVELOP OFF LAKE ERIE FROM
BUFFALO TO NIAGARA FALLS.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH THIS MORNING WITH ONLY MID-
HIGH CLOUDS. AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL
MOVE ACROSS LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME
LIGHT RAIN TO BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN
THE VFR CATEGORY WITH THIS. THEN ANOTHER ROUND OF SHOWERS WILL DROP
N-S THIS EVENING. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE
MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE
TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS
WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT
AND MONDAY...AS HIGH PRESSURE BUILDS IN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LEZ020-041.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL
MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
153 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY.
A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY...
FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK.
TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING
HUMIDITY INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LATE EVENING SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE INTO
PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E
GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE
WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF
OF THE STATE. HAVE THEREFORE RAISED TEMPS A BIT...WITH MINS
RUNNING IN THE M40S ACROSS MOST OF THE REGION.
THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH
PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST
TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS
OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE IN A FEW SPOTS
TOWARD DAWN. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR
MOST OF THE REGION...SO ANY FOG SHOULD BE ISOLATED.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN
STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER
SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY
TO MOSTLY SUNNY SKIES.
A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF
A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN
PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE
FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL
BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS.
HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE
NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR
80F THROUGHOUT THE LOWER SUSQ VALLEY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN
ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS
THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE
PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/
DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST
ACROSS THE SE. LOWS WILL BE NOTICEABLY MILDER...ONLY DROPPING INTO
THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE
ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT.
DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR
SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED
SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING
THE MORNING.
ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR
SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER
GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL
TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP
BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY
INT HE 40S ELSEWHERE.
MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND
AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST.
A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN
DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE
US. TEMPS WILL AGAIN MOVE ABOVE NORMAL.
THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM
OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT
AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY
NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY
EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE
CFRONT.
DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE
UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND
STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER
AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY
ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS
OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY
SKIES SHOULD PREVAIL ELSEWHERE.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
SFC HIGH PRES OVR PA AND ADJ STATES TDY WILL YIELD TO A COLD FRONT
PUSHING SEWD FROM THE LWR GRT LKS. THE FRONT WILL MOVE NW-SE THRU
THE AIRSPACE FROM LATE TONIGHT THRU THE DAYLIGHT HOURS ON SUNDAY.
WDLY SCT LGT SHOWERS/SPRINKLES SHOULD ACCOMPANY THE COLD
FRONT...FOLLOWED BY A BAND OF POST-FRONTAL LOW END VFR TO MVFR
CIGS. SFC WNDS WILL SHIFT FROM WSW TO NNW BEHIND THE FRONT. HIGH
PRES RETURNS VFR CONDS FOR MONDAY...BEFORE AN INCREASINGLY MOIST
SLY FLOW AND ASSOCD WARM FRONT THREATENS MVFR CIGS AND ISOLD CONVECTION
FOR TUES. A COLD FRONT PUSHING SEWD FROM THE GREAT LAKES WILL
LKLY BE A FOCUS FOR SCT SHOWERS/TSTMS THRU THE MIDDLE OF NEXT
WEEK.
OUTLOOK...
SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA.
MON...VFR. NO SIG WX.
TUE/WED...AM FOG PSBL. VFR WITH ISOLD-SCT TSTM IMPACTS PSBL.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
759 PM CDT SUN SEP 8 2013
.UPDATE...
A LOT OF FORECAST UNCERTAINTY AT THIS TIME. 18Z MODEL DATA IS MUCH
MORE BULLISH WITH LLJ BEING DISPLACED FURTHER EAST ACROSS THE
ABERDEEN CWA. THE HRRR DOES INDICATE AN INCREASE IN ELEVATED
CONVECTION DURING THE MID TO LATE EVENING...AND GIVEN MODEL
CHANGES WILL ACCEPT THAT AND INCREASE POPS A LITTLE. FURTHER WEST
IT APPEARS THERE WILL STILL BE SOME OPPORTUNITY FOR AN MCS OR TWO
COMING OFF THE HIGH PLAINS AND EAST ACROSS THE CWA OVERNIGHT. HRRR
CONTINUES TO BE QUITE BULLISH WITH THIS PROGNOSTICATION AND THUS
WILL MAINTAIN RELATIVELY HIGH POPS. TEMPERATURES ARE OKAY. UPDATES
OUT SOON.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH TUESDAY AM
WHILE PRECIPITATION HAS DISSIPATED...CONVECTIVE DEBRIS CONTINUES
TO MUDDY WHAT WAS ALREADY A COMPLEX FORECAST. DAYTIME HEATING IS
GREATEST ACROSS NORTHWEST COUNTIES...UNDER WHICH THE CAP IS THE
WEAKEST...WITH H7 TEMPERATURES ONLY BETWEEN +11 AND +12C. THE
MAIN SHORTWAVE IS STILL FAR TO THE WEST...WITH WARM ADVECTION
ALOFT. THERE IS STILL THE POTENTIAL FOR A SURFACE BASED STORM OR
TWO TO FORM ALONG THE ND/SD BORDER AND PUSH EAST...WEAKENING AS H7
TEMPERATURES WARM AND IT ENCOUNTERS MORE CLOUDY/LESS UNSTABLE AIR
IN THE EAST...AND IN FACT SOME OF THE HIGH RES GUIDANCE HINTS AT
SUCH. OTHERWISE...CONVECTION TODAY WILL BE LIMITED TO ELEVATED
WEAK STORMS OVER CENTRAL/WESTERN SD WHERE H7 WARM ADVECTION
STEEPENS MID LEVEL LAPSE RATES...AND SOME OF THE HIGH RES GUIDANCE
HAS SUGGESTED THIS OUTCOME. OF GREATEST CONCERN CONTINUES TO BE AS
THE SHORTWAVE APPROACHES...AND TEMPERATURES ALOFT COOL...WITH
INCREASING LOW LEVEL JET SUPPORT. STORMS IN THIS ENVIRONMENT FAVOR
SLOW EAST/NORTHEAST STORM MOTION...WITH NORTH DAKOTA GETTING THE
BEST COVERAGE...STILL LOOKING LIKE SCATTERED COVERAGE THIS SIDE OF
THE BORDER. GIVEN THE HEAVY RAIN LAST NIGHT IN CORSON
COUNTY...WENT FOR A FLASH FLOOD WATCH. STORMS PUSH EAST AND
DISSIPATE MONDAY AM. THE FRONT IS NOW PROGGED TO PUSH ALL THE WAY
THROUGH THE CWA BY MID DAY...WITH THE CAP IN PLACE FARTHER EAST
...PRE-FRONTAL CONVECTIVE ACTIVITY APPEARS UNLIKELY IN THE CWA. IN
THE POST FRONTAL ENVIRONMENT...COOLING ALOFT AND PLENTY OF DAYTIME
HEATING SUGGEST A CONTINUED THREAT FOR STORMS...WITH STRAIGHT
LINE HODOGRAPHS. MAIN QUESTION REVOLVES AROUND INSTABILITY AS WILL
SEE LOW LEVEL DRY AIR ADVECTION AS WELL.
.LONG TERM...TUESDAY THROUGH SUNDAY
BULK OF THE EXTENDED PERIOD LOOKS DRY AT THIS POINT. ON TUESDAY
DRIER AIR WILL BE FILTERING INTO THE REGION WITH NORTHWEST FLOW
ALOFT. CONDITIONS LOOK DRY ALL THE WAY THROUGH THE FIRST HALF OF
FRIDAY AS SFC HIGH PRESSURE BEGINS BUILDING SOUTH INTO THE AREA BY
THURSDAY. COOLER AIR ARRIVES ON THURSDAY AS WELL...SO THE 80S FOR
HIGHS ON TUESDAY AND WEDNESDAY WILL BE REPLACED BY 70S ON THURSDAY
AND FRIDAY. THE ONLY REAL SHOT FOR PRECIP DURING THE EXTENDED
FORECAST IS FRIDAY NIGHT THROUGH SATURDAY NIGHT AS SHORTWAVE
ENERGY MOVES INTO THE NORTHERN PLAINS AROUND THE UPPER RIDGE.
MODELS HAVE TRENDED FURTHER SOUTH WITH THIS FEATURE INITIALLY ON
FRIDAY...WITH MODELS SHOWING MOST QPF ACROSS NEBRASKA AND SOUTHERN
SOUTH DAKOTA. FAIRLY GOOD AGREEMENT ACTUALLY IN BRINGING PRECIP
INTO THE EASTERN CWA DURING THE DAY SATURDAY. FOR NOW HAVE
ACCEPTED ALLBLEND POPS WHICH HAVE 30S/40S FOR POPS FRIDAY NIGHT
THROUGH SATURDAY WHICH LOOKS GOOD AT THIS POINT.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
FOR THE MOST PART VFR CONDITIONS ARE EXPECTED THROUGH TONIGHT.
HOWEVER...SHOWERS AND STORMS ARE EXPECTED LATER THIS EVENING AND
OVERNIGHT. ANY STORMS COULD PRODUCE PERIODS OF IFR CONDITIONS.
FORECASTER CONFIDENCE IN PLACEMENT OF THE STORMS IS SOMEWHAT LOW
GIVEN A COMPLEX SETUP ACROSS THE REGION. FOR NOW EXPECT STORMS TO
FORM OUT WEST AND SOUTH AND MOVE NORTHEAST ACROSS THE REGION
OVERNIGHT. BEHIND THE STORMS SOME IFR CIGS/FOG COULD FORM IN COOL
LINGERING AIR BUT AGAIN FORECASTER CONFIDENCE IS LOW.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...FLASH FLOOD WATCH UNTIL 6 AM MDT MONDAY FOR CORSON.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...CONNELLY
LONG TERM...TMT
AVIATION...TDK
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1256 PM CDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1240 PM CDT SAT SEP 7 2013
BATCH OF SCATTERED SHOWERS WITH A FEW EMBEDDED LIGHTNING STRIKES
TRACKING ALONG THE BOUNDARY NEAR OUR SOUTHERN BORDER. THIS ACTIVITY
CONTINUES TO TRACK EAST SOUTHEAST AND SHOULD EXIT THE AREA WITHIN THE
NEXT FEW HOURS. WHILE CLEARING IS FORMING BEHIND THIS
ACTIVITY...CLOUD COVERAGE IS STALLING THE WARMING ACROSS OUR
SOUTHEASTERN HALF. DID LOWER HIGHS A FEW DEGREES MAINLY THROUGH
NORTHWEST IOWA AND ADJACENT AREAS WHERE THE CLOUDS WILL HOLD ON
LONGEST THIS AFTERNOON. THE ARRIVAL OF SUNSHINE ELSEWHERE SHOULD
ALLOW TEMPS TO SHOOT UP FAIRLY QUICKLY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT SEP 7 2013
TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH
THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL
RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE
HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE
HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE
MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE
MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH
WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST
AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000
J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM
700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO
BECOME ALL THAT ORGANIZED OR SEVERE.
BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH
ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING
UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX
EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE
BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE
ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY.
QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL
SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN
CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT.
HAVE RAISED SKY COVER IN THE EAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT SEP 7 2013
EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD
BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA.
THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT
ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF
INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY
ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST.
SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW
SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT
INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY
A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM
TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD
MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED
GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH
DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70.
LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES
KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE
UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND
THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING
ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW
LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH
OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND
THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14
CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30
POP IN THAT REGION.
MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD
APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING
AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY
WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF
THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS
HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF
THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST
OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS
COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST.
CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER
MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST
FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING
DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT
ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE
BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT
DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS
WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE
NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND
THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT.
INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND
THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST
FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT
LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL
ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR
INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS.
MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH
PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION
PARALLEL TO THE FRONT.
BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS
NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER
AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO
WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH
HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS
MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A
WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE
RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT
MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE
COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN
SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS
SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY
HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT.
LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR
NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH
OF TEMPERATURES THE FOLLOWING WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1240 PM CDT SAT SEP 7 2013
VFR CONDITION PREDOMINATE THROUGH THE TAF PERIOD. SCATTERED STORMS
FROM NEAR YANKTON EASTWARD INTO NORTHWEST IOWA WILL CONTINUE TO
DISSIPATE AS THEY TRACK EAST SOUTHEAST. COULD SEE A BRIEF DIP TO
LOWER CONDITIONS IN THUNDERSTORMS BUT ACTIVITY WILL COME TO AN END BY
20Z. MODELS HINTING AT THE POSSIBILITY OF SOME BROKEN STRATUS FORMING
TONIGHT...MAINLY ACROSS SOUTHWEST MINNESOTA. WILL LEAVE OUT MENTION
AT TAF SITES FOR NOW BUT WILL CONTINUE TO WATCH FOR DEVELOPMENT.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
622 AM CDT SAT SEP 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT SEP 7 2013
TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH
THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL
RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE
HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE
HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE
MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE
MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH
WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST
AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000
J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM
700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO
BECOME ALL THAT ORGANIZED OR SEVERE.
BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH
ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING
UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX
EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE
BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE
ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY.
QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL
SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN
CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT.
HAVE RAISED SKY COVER IN THE EAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT SEP 7 2013
EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD
BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA.
THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT
ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF
INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY
ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST.
SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW
SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT
INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY
A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM
TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD
MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED
GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH
DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70.
LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES
KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE
UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND
THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING
ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW
LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH
OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND
THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14
CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30
POP IN THAT REGION.
MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD
APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING
AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY
WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF
THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS
HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF
THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST
OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS
COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST.
CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER
MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST
FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING
DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT
ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE
BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT
DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS
WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE
NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND
THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT.
INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND
THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST
FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT
LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL
ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR
INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS.
MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH
PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION
PARALLEL TO THE FRONT.
BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS
NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER
AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO
WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH
HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS
MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A
WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE
RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT
MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE
COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN
SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS
SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY
HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT.
LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR
NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH
OF TEMPERATURES THE FOLLOWING WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 619 AM CDT SAT SEP 7 2013
A WEAK SHORT WAVE WILL MOVE THROUGH THE AREA THIS MORNING
RESULTING IN HIGH BASED ISOLATED-SCATTERED STORMS. EXPECT SKIES TO
BECOME PARTLY CLOUDY BEHIND THE WAVE. NORTHEAST FLOW WILL PREVAIL
ACROSS THE REGION BECOMING EASTERLY TONIGHT. THERE IS A CHACE THAT
STRATUS MAY TRY TO DEVELOP...THOUGH CONFDIENCE IS HIGHER EAST OF
I-29 AND HAVE NOT INCLUDED IN THE FORECAST QUITE YET.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
407 AM CDT SAT SEP 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT SEP 7 2013
TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH
THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL
RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE
HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE
HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE
MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE
MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH
WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST
AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000
J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM
700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO
BECOME ALL THAT ORGANIZED OR SEVERE.
BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH
ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING
UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX
EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE
BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE
ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY.
QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL
SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN
CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT.
HAVE RAISED SKY COVER IN THE EAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT SEP 7 2013
EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD
BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA.
THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT
ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF
INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY
ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST.
SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW
SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT
INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY
A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM
TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD
MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED
GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH
DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70.
LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES
KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE
UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND
THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING
ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW
LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH
OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND
THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14
CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30
POP IN THAT REGION.
MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD
APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING
AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY
WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF
THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS
HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF
THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST
OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS
COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST.
CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER
MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST
FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING
DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT
ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE
BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT
DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS
WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE
NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND
THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT.
INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND
THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST
FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT
LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL
ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR
INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS.
MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH
PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION
PARALLEL TO THE FRONT.
BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS
NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER
AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO
WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH
HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS
MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A
WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE
RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT
MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE
COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN
SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS
SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY
HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT.
LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR
NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH
OF TEMPERATURES THE FOLLOWING WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1054 PM CDT FRI SEP 6 2013
MOSTLY VFR THROUGH 08/06Z. AN EXCEPTION MAY BE PATCHY RADIATION
FOG 09Z-14Z IN SOUTHEAST PART OF THE AREA AS FLOW BECOMES LIGHT
AND BEST LOW LEVEL MOISTURE LINGERS...SO HAVE GONE FOR BRIEF MVFR
AT KSUX.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
122 PM CDT SUN SEP 8 2013
.DISCUSSION...
UPDATED FOR 12Z AVIATION DISCUSSION
&&
.PREV DISCUSSION... /ISSUED 942 AM CDT SUN SEP 8 2013/
NO CHANGES TO THE MORNING FORECAST ARE ANTICIPATED.
HAVE BEEN MONITORING MCS NEAR ST. LOUIS...WHICH IS SLOWLY
WEAKENING. THE LATEST HRRR AND 12Z NAM MODEL IS ALSO INDICATING
THIS TREND THROUGH THE EARLY AFTERNOON HOURS...WITH SOME ISOLATED
REDEVELOPMENT ON IT`S SOUTHERN FLANK LATER TODAY ACROSS OUR NORTH.
THUS LATE AFTERNOON AND OVERNIGHT RAIN CHANCES LOOK TO BE ON
TRACK FOR NOW. QUESTION THAT ARISES FOR THE AFTERNOON FORECAST
PACKAGE WILL BE COVERAGE AFTER SUNSET AS THE NAM KEEPS ACTIVITY
GOING THROUGH LATE MONDAY MORNING. IF THIS SCENARIO
UNFOLDS...SEVERAL LOCATIONS ALONG AND NORTH OF INTERSTATE FORTY
COULD RECEIVE A WELCOMED SIGNIFICANT RAINFALL.
HIGH LEVEL MOISTURE FROM COMPLEX WILL CONTINUE TO BUILD SOUTH
INTO OUR AREA OVER THE NEXT 3 TO 6 HOURS...KEEPING HIGHS A FEW
DEGREES BELOW GUIDANCE.
JAB
PREV DISCUSSION... /ISSUED 507 AM CDT SUN SEP 8 2013/
FEW CHANGES TO RECENT FORECASTS. A LARGE AN UNSEASONABLY STRONG
UPPER LEVEL HIGH PRESSURE RIDGE REMAINS THE PRIMARY WEATHER
FEATURE...WHICH WILL RESULT IN DAYTIME TEMPS AVERAGING SEVERAL
CATEGORIES ABOVE EARLY/MID SEPTEMBER CLIMATOLOGICAL NORMALS.
THE UPPER RIDGE WAS CENTERED OVER THE CENTRAL PLAINS EARLY THIS
MORNING...WITH WEAK NORTH/NORTHWEST UPPER LEVEL FLOW OVER THE
MIDSOUTH. GOES WATER VAPOR IMAGERY SHOWED A WEAK SHORTWAVE
EMBEDDED IN THIS NORTHWEST FLOW OVER CENTRAL IL. THIS FEATURE WILL
DROP INTO THE MIDSOUTH BY THIS EVENING... SLOWING ITS PROGRESS
WITH THE APPROACH OF THE UPPER RIDGE CENTER. A FEW THUNDERSTORMS
MAY OCCUR TO THE NORTH AND NORTHEAST OF MEMPHIS THIS AFTERNOON AND
EARLY EVENING...WHERE COOLER MIDLEVEL TEMPS AID IN WEAKENING THE
OTHERWISE ROBUST CINH /CONVECTIVE INHIBITION/.
THE GFS AND NAM DIFFER GREATLY WITH DAYTIME RAIN CHANCES MONDAY
AND TUESDAY. THE NAM CONTINUES TO DEVELOP RATHER ROBUST QPF FIELDS
UNDER THE UPPER RIDGE CENTER...WHILE THE GFS SHOWS MUCH MORE LIMITED
QPF. SOUNDINGS ARE SIMILAR ENOUGH BETWEEN THE TWO MODELS AND
SUSPECT THE DIFFERENCES ARE PRIMARILY DUE TO CONVECTIVE PARAMETRIZATION
IN THE WEAK KINEMATIC ENVIRONMENT UNDER THE ROBUST UPPER RIDGE.
THE DRIER GFS APPEARS TO BE WELL CORROBORATED BY THE ECMWF AND AS
SUCH HAS BEEN USED AS THE BASIS FOR FORECAST POPS.
MIDWEEK PERIODS LOOK TO BE HOT UNDER THE UPPER RIDGE. A DEEP BUT
PROGRESSIVE UPPER TROF WILL DROP INTO THE NORTHEASTERN THIRD OF THE
U.S. ON THURSDAY...BRINGING UPPER LEVEL NORTHWEST FLOW AND ASSOCIATED
SURFACE COLD FRONTAL PASSAGE TO THE MIDSOUTH. THIS FRONT WILL PROVIDE
FOCUS FOR ISOLATED THUNDERSTORM DEVELOPMENT...FOLLOWED BY NOTICEABLY
LOWER DEWPOINTS A SOME RELIEF FROM THE HEAT HEADED INTO THE EARLY
WEEKEND.
THE UPPER LEVEL RIDGE WILL QUICKLY BUILD BACK BY SUNDAY...CENTERED
OVER THE OZARK PLATEAU. THIS RIDGE WILL THEN EXPAND EASTWARD
THROUGH THE MIDDLE OF NEXT WEEK... DOMINATING THE SOUTHEASTERN
THIRD OF THE LOWER 48 BEYOND THE MID SEPTEMBER MARK.
PWB
&&
.AVIATION...
18Z TAF SET
VFR CONDITIONS EXPECTED OVER NEXT 24 HOURS. A WEAK DISTURBANCE
JUST SOUTH OF KSTL WILL PUSHING SOUTH ALONG THE MS RIVER THIS
AFTERNOON AND INT THE MIDSOUTH THIS EVENING. THIS COULD KICK OFF
A FEW SHRAS ACROSS KJBR AND KMKL LATER TONIGHT. SOME LIGHT FOG IS
POSSIBLE AT KMKL LATE TONIGHT. LIGHT SW/WSW WINDS EXPECTED THROUGH THE
PERIOD.
SJM
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 94 76 94 75 / 10 10 20 10
MKL 92 68 92 69 / 20 20 20 10
JBR 96 71 93 70 / 20 20 20 10
TUP 94 70 94 70 / 0 10 20 10
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
655 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION WILL SHIFT EAST PASSING OFF THE
COAST LATER THIS AFTERNOON AND EVENING. A WEAK COOL FRONT WILL
APPROACH FROM THE NORTHWEST LATE TONIGHT BEFORE SLIDING SOUTH
ACROSS THE REGION LATER SUNDAY...AND INTO THE CAROLINAS SUNDAY
EVENING. WEAK HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA BEHIND
THE FRONT SUNDAY NIGHT AND THEN OFFSHORE THE MID ATLANTIC COAST
ON MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 210 AM EDT SATURDAY...
GRADIENT BETWEEN LOWER DEWPOINT AIR TO THE NORTH AND SOMEWHAT
MORE MOIST AIR TO THE SOUTH REMAINS ACROSS THE CENTRAL CWA EARLY
THIS MORNING. THIS IN COMBO WITH WEAK 9H SE UPSLOPE FLOW AND AN
AXIS OF HIGHER THETA-E ALONG THE SRN BLUE RIDGE HAS LED TO THE
DEVELOPMENT OF A STRATO-CU LAYER UNDER THE INVERSION FROM NW NC
INTO THE NEW RIVER VALLEY ATTM. EXPECT THIS CANOPY MAY INCREASE
SOME THROUGH DAYBREAK AS WELL AS FOG ALONG THE PERIMETER GIVEN
RIDGING OVERHEAD SO BEEFED UP CLOUDS/FOG TO INIT BUT STILL DRY.
OTRW WEAK MID LEVEL WAVE RIDING SOUTH THRU WVA WILL DROP
THROUGH THE REGION TODAY AS SURFACE HIGH PRESSURE GETS BUMPED
EAST. THIS SHOULD ALLOW THE LOW LEVEL FLOW TO QUICKLY VEER FROM
SOUTH/SE EARLY TO A MORE WESTERLY COMPONENT DURING THE AFTERNOON
AS THE WAVE ALOFT PASSES AND THE HIGH SLIDES OFFSHORE. LATEST
GUIDANCE RH FIELDS SHOW THIS ENOUGH TO SCOUR OUT RESIDUAL LOW
CLOUDS BY MID OR LATE MORNING WITH ONLY THE HRRR HANGING ONTO
CLOUDS ALONG THE SRN FOOTHILLS A BIT LONGER. THUS APPEARS
BECOMING MOSTLY SUNNY ON TRACK WITH ONLY SOME CU AND HIGH CLOUDS
AROUND WITH THE IMPULSE ALOFT THIS AFTERNOON ONCE ANY LOW DECK
FADES. MODELS DO SHOW A LOBE OF DECENT INSTABILITY AND WEAK
CONVERGENCE FAR SW INTO NW NC LATER THIS AFTERNOON SO AN ISOLD
MOUNTAIN TSRA CANT TOTALLY BE RULED OUT BUT TOO IFFY UNDER DRY
ENTRAINMENT TO INCLUDE MENTION FOR THE MOST PART. OTRW GIVEN A
MORE WESTERLY TRAJECTORY AND 85H WARMING OF A FEW DEGREES DURING
THE DAY...BUMPED UP HIGHS A LITTLE ESPCLY EAST WHERE EXPECT LOW
80S WITH MAINLY 70S ELSW.
NEXT COLD FRONT ACROSS THE GREAT LAKES LATER TODAY WILL BE
APPROACHING FROM THE NORTH LATE TONIGHT AND PERHAPS SPREADING
A PRECEDING BAND OF MID/HIGH CLOUDS IN FROM THE NW OVERNIGHT.
HOWEVER AIR AHEAD OF THE BOUNDARY REMAINS QUITE DRY ALOFT AND
GIVEN A STRONG NW TRAJECTORY THINKING MOSTLY CLEAR OVERALL UNDER
LINGERING HIGH PRESSURE. INCREASING WEST/NW WINDS ALOFT SHOULD
ALSO ACT TO KEEP TEMPS UP SOME ON THE RIDGES AHEAD OF THE
FRONT...WHILE THE VALLEYS AND SPOTS OUT EAST SPILL BACK INTO THE
MID/UPPER 50S FOR LOWS UNDER BETTER RADIATIONAL COOLING.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM EDT SATURDAY...
A COLD FRONT WILL MOVE THROUGH THE REGION ON SUNDAY IN
ASSOCIATION WITH AN UPPER TROUGH PROGRESSING THROUGH NEW ENGLAND.
GUIDANCE FOR THE PAST SEVERAL DAYS HAS FLIP-FLOPPED ON HOW
EXPANSIVE ANY ASSOCIATED PRECIPITATION WILL BE WITH THIS FEATURE
AS IT MOVES THROUGH OUR REGION. THIS MORNING/S FORECAST WILL BE
COMPARABLE TO THE ONE OFFERED YESTERDAY AFTERNOON...WITH SCATTERED
SHOWERS EXPECTED ACROSS THE MOUNTAINS BY THE AFTERNOON WITH
ISOLATED COVERAGE ACROSS ABOUT ONE TIER OF COUNTIES EAST OF THE
CREST OF THE BLUE RIDGE. ISOLATED THUNDERSTORMS ARE ALSO FORECAST.
TEMPERATURES WILL CONTINUE THEIR TREND OF BEING WARMER EACH DAY ON
SUNDAY PRE- COLD FRONT. AROUND 80 TO THE MID 80S ARE EXPECTED
ACROSS THE MOUNTAINS...WITH UPPER 80S COMMON ACROSS THE PIEDMONT.
BEHIND THE FRONT...HIGH PRESSURE WILL BUILD OFF THE MID-ATLANTIC
COAST AND FLOW AROUND THE HIGH WILL GRADUALLY USHER IN
SOUTHWEST FLOW INTO THE REGION...ESPECIALLY ACROSS THE WESTERN
PARTS OF THE AREA. THE INCREASED MOISTURE...DAYTIME HEATING...AND
A WEAK CAP WITH THE HIGH SO FAR OFF SHORE...WILL YIELD A SCENARIO
WHERE AFTERNOON CONVECTION IS EXPECTED. WITH NO ORGANIZED UPPER
LEVEL SUPPORT...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED
AT BEST. THE SOUTHWEST FLOW WILL ALSO ALLOW FOR A TREND OF MILDER
TEMPERATURES STARTING ON TUESDAY AFTER A BRIEF COOL DOWN ON
MONDAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 345 PM EDT FRIDAY...
HIGH PRESSURE WILL ADVANCE EAST OFF THE COAST OF NEW ENGLAND ON
TUESDAY...ALLOWING WINDS TO BECOME MORE SOUTHWESTERLY ACROSS THE
MID ATLANTIC...DRAWING DEEPER TROPICAL MOISTURE BACK INTO THE
REGION. AS SUCH...WE CAN EXPECT A RETURN OF AFTERNOON SHOWERS AND
THUNDERSTORMS...WITH INCREASING COVERAGE EACH DAY THROUGH THE
MIDDLE OF THE NEXT WORKWEEK. UPPER LEVEL RIDGING OVER THE CENTRAL
PLAINS WILL BUILD EAST THROUGH THE PERIOD...WHICH WILL RETURN A
MORE SUMMER LIKE FEEL TO THE REGION BY PUSHING TEMPERATURES
SLIGHTLY ABOVE NORMAL FOR THE EARLY HALF OF SEPTEMBER.
BY THURSDAY NIGHT...A LOW PRESSURE SYSTEM WILL PUSH ACROSS THE
GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. MAY SEE A FEW
STRONG TO SEVERE STORMS DEVELOP AHEAD OF THE FRONT...BUT RIGHT NOW
WILL BE A LITTLE MORE CONCERNED WITH THE POTENTIAL FOR HEAVY RAIN
DUE TO THE ABUNDANT ATMOSPHERIC MOISTURE ACROSS OUR AREA AND LIGHT
UPPER LEVEL WINDS...RESULTING IN POTENTIALLY SLOW MOVING STORMS.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 640 AM EDT SATURDAY...
WIDE VARIETY OF CONDITIONS TO INIT THIS MORNING WITH IFR/LIFR IN
FOG/STRATUS IN SOME OF THE VALLEYS SUCH AS LWB...AND LOW END MVFR
CIGS IN SPOTS OVER THE EAST LIKE DAN/LYH PER BANDS OF STRATO-CU.
OTRW OUTSIDE OF PATCHY LOW CLOUDS/FOG...MAINLY VFR UNDER PERIODIC
HIGH CLOUDS WITH A WEAK DISTURBANCE APPROACHING FROM THE NW. STILL
EXPECTING ANY LOW CLOUDS AND/OR FOG TO FADE BY MID OR LATE
MORNING IF NOT SOONER AS THE FLOW TURNS MORE SW TO W BY AFTERNOON.
HOWEVER WILL CONTINUE LOW CONDITIONS FOR A WHILE LONGER AND
PERHAPS SPILL LOW DECK WESTWARD BACK TO THE BLUE RIDGE BEFORE
TRANSITIONING ALL LOCATIONS TO A SCTD-BKN CU CANOPY WITH HEATING
THIS AFTERNOON.
SURFACE HIGH PRESSURE OVER SOUTHERN NEW ENGLAND WILL DRIFT SOUTH
TO ALONG THE MID ATLANTIC COAST BY THIS EVENING PROVIDING MAINLY
CLEAR SKIES OUTSIDE OF PASSING MID/HIGH CLOUDS OVERNIGHT. AGAIN
APPEARS THE DEEPER VALLEYS SUCH AS LWB WILL DROP OFF TO IFR/LIFR
AT TIMES WITH MAINLY VFR ELSW OUTSIDE OF PATCHY FOG LATE IN THE
EAST.
ANOTHER COLD FRONT...ARRIVING FROM THE NW...WILL MOVE INTO THE
AREA LATE SUNDAY...THEN STALL AND EVENTUALLY WASH OUT JUST TO OUR
SOUTH EARLY NEXT WEEK AS HIGH PRESSURE FROM THE MIDWEST BUILDS
EAST TOWARD THE MID-ATLANTIC. THIS MAY SPARK A ROUND OF SHRA/TSRA
ESPCLY MOUNTAINS SUNDAY AFTERNOON. OTRW EXPECT A RETURN TO MORE
TYPICAL SUMMERLIKE WEATHER WITH INCREASING CHANCES FOR DIURNALLY-
DRIVEN SHRA/TSRA INTO SUNDAY EVENING WHEN THE FRONT MOVES SOUTH
THROUGH THE REGION. APPEARS TO BE MOSTLY MVFR CIGS AT WORSE
OUTSIDE MORNING FOG/LOW CLOUDS WHICH WILL LIKELY BE INCREASING AS
THE AIR MASS ACROSS THE REGION BECOMES INCREASINGLY MOIST WITH
DEWPOINTS IN THE 60S MOUNTAINS AND NEAR 70 PIEDMONT. AT THIS
POINT...NO WIDESPREAD EXTENDED DURATION OF POOR AVIATION
CONDITIONS ARE EXPECTED THROUGH MID WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/WERT
NEAR TERM...JH
SHORT TERM...DS
LONG TERM...NF
AVIATION...JH/PM/WERT/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
323 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION WILL SHIFT EAST PASSING OFF THE
COAST LATER THIS AFTERNOON AND EVENING. A WEAK COOL FRONT WILL
APPROACH FROM THE NORTHWEST LATE TONIGHT BEFORE SLIDING SOUTH
ACROSS THE REGION LATER SUNDAY...AND INTO THE CAROLINAS SUNDAY
EVENING. WEAK HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA BEHIND
THE FRONT SUNDAY NIGHT AND THEN OFFSHORE THE MID ATLANTIC COAST
ON MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 210 AM EDT SATURDAY...
GRADIENT BETWEEN LOWER DEWPOINT AIR TO THE NORTH AND SOMEWHAT
MORE MOIST AIR TO THE SOUTH REMAINS ACROSS THE CENTRAL CWA EARLY
THIS MORNING. THIS IN COMBO WITH WEAK 9H SE UPSLOPE FLOW AND AN
AXIS OF HIGHER THETA-E ALONG THE SRN BLUE RIDGE HAS LED TO THE
DEVELOPMENT OF A STRATO-CU LAYER UNDER THE INVERSION FROM NW NC
INTO THE NEW RIVER VALLEY ATTM. EXPECT THIS CANOPY MAY INCREASE
SOME THROUGH DAYBREAK AS WELL AS FOG ALONG THE PERIMETER GIVEN
RIDGING OVERHEAD SO BEEFED UP CLOUDS/FOG TO INIT BUT STILL DRY.
OTRW WEAK MID LEVEL WAVE RIDING SOUTH THRU WVA WILL DROP
THROUGH THE REGION TODAY AS SURFACE HIGH PRESSURE GETS BUMPED
EAST. THIS SHOULD ALLOW THE LOW LEVEL FLOW TO QUICKLY VEER FROM
SOUTH/SE EARLY TO A MORE WESTERLY COMPONENT DURING THE AFTERNOON
AS THE WAVE ALOFT PASSES AND THE HIGH SLIDES OFFSHORE. LATEST
GUIDANCE RH FIELDS SHOW THIS ENOUGH TO SCOUR OUT RESIDUAL LOW
CLOUDS BY MID OR LATE MORNING WITH ONLY THE HRRR HANGING ONTO
CLOUDS ALONG THE SRN FOOTHILLS A BIT LONGER. THUS APPEARS
BECOMING MOSTLY SUNNY ON TRACK WITH ONLY SOME CU AND HIGH CLOUDS
AROUND WITH THE IMPULSE ALOFT THIS AFTERNOON ONCE ANY LOW DECK
FADES. MODELS DO SHOW A LOBE OF DECENT INSTABILITY AND WEAK
CONVERGENCE FAR SW INTO NW NC LATER THIS AFTERNOON SO AN ISOLD
MOUNTAIN TSRA CANT TOTALLY BE RULED OUT BUT TOO IFFY UNDER DRY
ENTRAINMENT TO INCLUDE MENTION FOR THE MOST PART. OTRW GIVEN A
MORE WESTERLY TRAJECTORY AND 85H WARMING OF A FEW DEGREES DURING
THE DAY...BUMPED UP HIGHS A LITTLE ESPCLY EAST WHERE EXPECT LOW
80S WITH MAINLY 70S ELSW.
NEXT COLD FRONT ACROSS THE GREAT LAKES LATER TODAY WILL BE
APPROACHING FROM THE NORTH LATE TONIGHT AND PERHAPS SPREADING
A PRECEDING BAND OF MID/HIGH CLOUDS IN FROM THE NW OVERNIGHT.
HOWEVER AIR AHEAD OF THE BOUNDARY REMAINS QUITE DRY ALOFT AND
GIVEN A STRONG NW TRAJECTORY THINKING MOSTLY CLEAR OVERALL UNDER
LINGERING HIGH PRESSURE. INCREASING WEST/NW WINDS ALOFT SHOULD
ALSO ACT TO KEEP TEMPS UP SOME ON THE RIDGES AHEAD OF THE
FRONT...WHILE THE VALLEYS AND SPOTS OUT EAST SPILL BACK INTO THE
MID/UPPER 50S FOR LOWS UNDER BETTER RADIATIONAL COOLING.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM EDT SATURDAY...
A COLD FRONT WILL MOVE THROUGH THE REGION ON SUNDAY IN
ASSOCIATION WITH AN UPPER TROUGH PROGRESSING THROUGH NEW ENGLAND.
GUIDANCE FOR THE PAST SEVERAL DAYS HAS FLIP-FLOPPED ON HOW
EXPANSIVE ANY ASSOCIATED PRECIPITATION WILL BE WITH THIS FEATURE
AS IT MOVES THROUGH OUR REGION. THIS MORNING/S FORECAST WILL BE
COMPARABLE TO THE ONE OFFERED YESTERDAY AFTERNOON...WITH SCATTERED
SHOWERS EXPECTED ACROSS THE MOUNTAINS BY THE AFTERNOON WITH
ISOLATED COVERAGE ACROSS ABOUT ONE TIER OF COUNTIES EAST OF THE
CREST OF THE BLUE RIDGE. ISOLATED THUNDERSTORMS ARE ALSO FORECAST.
TEMPERATURES WILL CONTINUE THEIR TREND OF BEING WARMER EACH DAY ON
SUNDAY PRE- COLD FRONT. AROUND 80 TO THE MID 80S ARE EXPECTED
ACROSS THE MOUNTAINS...WITH UPPER 80S COMMON ACROSS THE PIEDMONT.
BEHIND THE FRONT...HIGH PRESSURE WILL BUILD OFF THE MID-ATLANTIC
COAST AND FLOW AROUND THE HIGH WILL GRADUALLY USHER IN
SOUTHWEST FLOW INTO THE REGION...ESPECIALLY ACROSS THE WESTERN
PARTS OF THE AREA. THE INCREASED MOISTURE...DAYTIME HEATING...AND
A WEAK CAP WITH THE HIGH SO FAR OFF SHORE...WILL YIELD A SCENARIO
WHERE AFTERNOON CONVECTION IS EXPECTED. WITH NO ORGANIZED UPPER
LEVEL SUPPORT...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED
AT BEST. THE SOUTHWEST FLOW WILL ALSO ALLOW FOR A TREND OF MILDER
TEMPERATURES STARTING ON TUESDAY AFTER A BRIEF COOL DOWN ON
MONDAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 345 PM EDT FRIDAY...
HIGH PRESSURE WILL ADVANCE EAST OFF THE COAST OF NEW ENGLAND ON
TUESDAY...ALLOWING WINDS TO BECOME MORE SOUTHWESTERLY ACROSS THE
MID ATLANTIC...DRAWING DEEPER TROPICAL MOISTURE BACK INTO THE
REGION. AS SUCH...WE CAN EXPECT A RETURN OF AFTERNOON SHOWERS AND
THUNDERSTORMS...WITH INCREASING COVERAGE EACH DAY THROUGH THE
MIDDLE OF THE NEXT WORKWEEK. UPPER LEVEL RIDGING OVER THE CENTRAL
PLAINS WILL BUILD EAST THROUGH THE PERIOD...WHICH WILL RETURN A
MORE SUMMER LIKE FEEL TO THE REGION BY PUSHING TEMPERATURES
SLIGHTLY ABOVE NORMAL FOR THE EARLY HALF OF SEPTEMBER.
BY THURSDAY NIGHT...A LOW PRESSURE SYSTEM WILL PUSH ACROSS THE
GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. MAY SEE A FEW
STRONG TO SEVERE STORMS DEVELOP AHEAD OF THE FRONT...BUT RIGHT NOW
WILL BE A LITTLE MORE CONCERNED WITH THE POTENTIAL FOR HEAVY RAIN
DUE TO THE ABUNDANT ATMOSPHERIC MOISTURE ACROSS OUR AREA AND LIGHT
UPPER LEVEL WINDS...RESULTING IN POTENTIALLY SLOW MOVING STORMS.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1250 AM EDT SATURDAY...
OVERALL STILL LOOKING AT ISSUES WITH EITHER FOG OR STRATOCU/STRATUS
ACROSS THE AREA LATE TONIGHT. THE LATEST NAM IS AGGRESSIVE SHOWING
REFORMATION OF LOWER CIGS ACROSS MOST OF THE AREA UNDER AN
INVERSION. MEANWHILE THE GFS/CMC ARE CLEARING THINGS OUT ALTHOUGH
THE CMC ACTUALLY SHOWS REDEVELOPMENT WEST OF THE BLUE RIDGE AND
INTO THE ALLEGHANYS DURING THE EARLY MORNING HOURS. THUS HAVE
CONTINUED TO LEAN THE AVIATION FORECAST MORE TOWARD THE CLOUDIER
NAM IN THE WEST AND A BLEND ELSW THROUGH EARLY SAT MORNING.
THUS MEDIUM TO HIGH CONFIDENCE THAT ALL TAF SITES WILL BE GETTING
AT LEAST A BKN CIG OF VFR AT ROA/LYH/DAN BETWEEN 2AM AND 6AM.
MEANWHILE BLF/BCB/LWB WILL BE DEALING WITH AN MVFR CIG FORMING
GIVEN THAT ELEVATIONS ARE HIGHER ALTHOUGH LWB MAY STAY CLEAR
LONGER BEFORE FOG FORMS WITH JUST SOME HIGH CLOUDS AROUND.
POTENTIAL SE UPSLOPE FLOW MAY CAUSE CIG TO DROP UNDER 1KFT AT
TIMES IN THE MORNING ALONG THE BLUE RIDGE SO HAVE A TEMPO GROUP
TO COVER THIS. STILL CANNOT RULE OUT DENSE FOG AT LWB BUT MAY BE
ENOUGH MIXING TO CLEAR THEM OUT FASTER SAT MORNING INTO AN MVFR
CIG...WHILE BCB REMAINS AT THE TOP END OF MVFR. ALL SITES WILL BE
VFR BY LATE MORNING/MIDDAY SAT AS WINDS SHIFT TO THE WEST AND SW.
SURFACE HIGH PRESSURE OVER SOUTHERN NEW ENGLAND WILL DRIFT SOUTH
TO ALONG THE MID ATLANTIC COAST BY SATURDAY EVENING PROVIDING
MAINLY CLEAR SKIES OUTSIDE OF HIGH CLOUDS.
ANOTHER COLD FRONT...ARRIVING FROM THE NW...WILL MOVE INTO THE
AREA LATE IN THE WEEKEND...THEN STALL AND EVENTUALLY WASH OUT JUST
TO OUR SOUTH EARLY NEXT WEEK AS HIGH PRESSURE FROM THE MIDWEST
BUILDS EAST TOWARD THE MID-ATLANTIC. EXPECT A RETURN TO MORE
TYPICAL SUMMERLIKE WEATHER WITH INCREASING CHANCES FOR DIURNALLY-
DRIVEN SHRA/TSRA ON SUNDAY WHEN THE FRONT MOVES SOUTH THROUGH THE
REGION. APPEARS TO BE MOSTLY MVFR CIGS AT WORSE OUTSIDE MORNING
FOG/LOW CLOUDS WHICH WILL LIKELY BE INCREASING AS THE AIR MASS
ACROSS THE REGION BECOMES INCREASINGLY TROPICAL WITH DEWPOINTS IN
THE 60S MOUNTAINS AND NEAR 70 PIEDMONT. AT THIS POINT...NO
WIDESPREAD EXTENDED DURATION OF POOR AVIATION CONDITIONS ARE
EXPECTED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/WERT
NEAR TERM...JH
SHORT TERM...DS
LONG TERM...NF
AVIATION...JH/PM/WERT/WP
AREA FORECAST DISCUSSION
NWS SPOKANE WA
431 AM PDT Sat Sep 7 2013
.SYNOPSIS...
The low pressure system responsible for showers and thunderstorms
the last couple of days will bring another round of wet weather to
the Cascades and northern mountains again today. Sunday will be a
drier day for most of the Inland Northwest with showers limited to
mainly the Idaho Panhandle. Dry, summer-like weather will return
Monday through Thursday as a strong high pressure ridge develops
over the region.
&&
.DISCUSSION...
Today through Sunday...A large closed low near Republic will be
nearly stationary today...before moving east towards the North
Idaho Panhandle tonight...and then exiting the area into Montana
on Sunday.
For this morning main focus is the wrap around band near the North
Washington Cascades on the back side of the low where a steady
light rain has been falling around Stehekin. The HRRR has been
consistent with a large area of light rain over far southwest BC
dropping southeast into Mazama, Stehekin early this morning
spreading east into Chelan...Brewster...and the Waterville Plateau
during the mid morning hours. While this rain will be
light...additional rain on saturated ground where mud slides have
already occurred may result in additional slides although
confidence is marginal of this. Given uncertainty will continue
with current Flash Flood Watches for the East Slopes of the
Cascades and Wenatchee area. This wrap around band will swing
northeast towards Colville and Chewelah during the early
afternoon. Cloud cover associated with this may limit thunderstorm
chances this afternoon over the Northeast Washington Mountains and
Idaho Panhandle. West of this band over the Okanogan Highlands,
Okanogan Valley, and East Slopes of the Cascades a better
potential for isolated thunderstorms exists with sun breaks more
likely to develop. Less instability will exist from Spokane
southward due to further proximity from low with only isolated
showers at most expected for today. Cloud cover today will keep
temperatures below average over all of the region.
Tonight showers will decrease with the loss of daytime heating and
be confined mainly to northeast Washington and North Idaho with
the closed low tracking across this region. Then on Sunday showers
will continue in these areas although with the low departing out
of the area showers will only be scattered in nature with a slight
chance of afternoon thunderstorms. A short wave ridge will
approach the Cascades late Sunday afternoon which will allow for
more pronounced warming over Central Washington with less cloud
cover and showers compared to today. JW
Sunday Night: The exiting upper trough may yield some early
evening showers over the Idaho Panhandle, but 500mb temperatures
will be warming and instability profiles don`t suggest more than
isolated thunder potential prior to sunset.
Monday through Friday: Summer will return next week with
temperatures well above average. There is good model agreement
through about Thursday that a high amplitude high pressure ridge
will develop over the Pacific Northwest. Wednesday and Thursday
look to be the warmest days of the week with 850mb temperatures in
the 22-24C range. Many lowland areas will be in the upper 80s to
lower 90s which is about 10 degrees above average.
Forecast confidence diminished markedly Friday into next weekend.
There is very little agreement between the 00z models and run-to-
run consistency has not been good either. A cooling trend into
next weekend is probable, but the timing/track/intensity of an
incoming Pacific trough (and subsequent ridge breakdown) is
highly uncertain at this time. /GKoch
&&
.AVIATION...
06Z TAFS: Low pressure will remain over the region through 12z
Sunday. The low will be positioned over the northern mountains with
the bulk of the showers occurring in the Cascades and areas north of
the Columbia Basin. Isolated afternoon thunderstorms are also
expected in these areas. Several cloud layers will be present with
mid level clouds associated with the low as well as lower cloud
layers this morning due to abundant boundary layer moisture. CIGS
will be primarily VFR...with occasional MVFR CIGS possible around
Wenatchee, Moses Lake, and Spokane area TAFS.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 70 54 77 56 81 57 / 20 20 10 10 0 0
Coeur d`Alene 70 54 74 54 81 55 / 20 20 20 10 0 0
Pullman 72 49 75 49 81 49 / 10 10 10 10 0 0
Lewiston 80 57 83 59 87 59 / 10 10 10 0 0 0
Colville 70 50 81 51 85 51 / 70 30 20 10 0 0
Sandpoint 70 49 73 48 78 47 / 50 30 40 20 10 10
Kellogg 71 53 71 54 79 54 / 20 20 40 20 10 10
Moses Lake 74 53 84 55 86 55 / 20 10 0 0 0 0
Wenatchee 73 57 83 60 85 60 / 50 20 0 0 0 0
Omak 74 54 83 56 86 57 / 70 30 10 10 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flash Flood Watch through this evening for East Slopes Northern
Cascades-Wenatchee Area.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
238 AM PDT Sat Sep 7 2013
.SYNOPSIS...
The low pressure system responsible for showers and thunderstorms
the last couple of days will bring another round of wet weather to
the Cascades and northern mountains again today. Sunday will be a
drier day for most of the Inland Northwest with showers limited to
mainly the Idaho Panhandle. Dry, summer-like weather will return
Monday through Thursday as a strong high pressure ridge develops
over the region.
&&
.DISCUSSION...
Today through Sunday...A large closed low near Republic will be
nearly stationary today...before moving east towards the North
Idaho Panhandle tonight...and then exiting the area into Montana
on Sunday.
For this morning main focus is the wrap around band near the North
Washington Cascades on the back side of the low where a steady
light rain has been falling around Stehekin. The HRRR has been
consistent with a large area of light rain over far southwest BC
dropping southeast into Mazama, Stehekin early this morning
spreading east into Chelan...Brewster...and the Waterville Plateau
during the mid morning hours. While this rain will be
light...additional rain on saturated ground where mud slides have
already occurred may result in additional slides although
confidence is marginal of this. Given uncertainty will continue
with current Flash Flood Watches for the East Slopes of the
Cascades and Wenatchee area. This wrap around band will swing
northeast towards Colville and Chewelah during the early
afternoon. Cloud cover associated with this may limit thunderstorm
chances this afternoon over the Northeast Washington Mountains and
Idaho Panhandle. West of this band over the Okanogan Highlands,
Okanogan Valley, and East Slopes of the Cascades a better
potential for isolated thunderstorms exists with sun breaks more
likely to develop. Less instability will exist from Spokane
southward due to further proximity from low with only isolated
showers at most expected for today. Cloud cover today will keep
temperatures below average over all of the region.
Tonight showers will decrease with the loss of daytime heating and
be confined mainly to northeast Washington and North Idaho with
the closed low tracking across this region. Then on Sunday showers
will continue in these areas although with the low departing out
of the area showers will only be scattered in nature with a slight
chance of afternoon thunderstorms. A short wave ridge will
approach the Cascades late Sunday afternoon which will allow for
more pronounced warming over Central Washington with less cloud
cover and showers compared to today. JW
Sunday Night: The exiting upper trough may yield some early
evening showers over the Idaho Panhandle, but 500mb temperatures
will be warming and instability profiles don`t suggest more than
isolated thunder potential prior to sunset.
Monday through Friday: Summer will return next week with
temperatures well above average. There is good model agreement
through about Thursday that a high amplitude high pressure ridge
will develop over the Pacific Northwest. Wednesday and Thursday
look to be the warmest days of the week with 850mb temperatures in
the 22-24C range. Many lowland areas will be in the upper 80s to
lower 90s which is about 10 degrees above average.
Forecast confidence diminished markedly Friday into next weekend.
There is very little agreement between the 00z models and run-to-
run consistency has not been good either. A cooling trend into
next weekend is probable, but the timing/track/intensity of an
incoming Pacific trough (and subsequent ridge breakdown) is
highly uncertain at this time. /GKoch
&&
.AVIATION...
06Z TAFS: The pesky and very slow moving low pressure system will
continue to produce scattered precipitation through Saturday night
across the forecast area. While a mid level deck is expected
around the region there should be a break in the precipitation
late tonight...before picking up Saturday afternoon again. At this
time anything below vfr conditions is not expected...although some
fog will be possible early Saturday morning for the KGEG-KCOE
corridor. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 70 54 77 56 81 57 / 20 20 10 10 0 0
Coeur d`Alene 70 54 74 54 81 55 / 20 20 20 10 0 0
Pullman 72 49 75 49 81 49 / 10 10 10 10 0 0
Lewiston 80 57 83 59 87 59 / 10 10 10 0 0 0
Colville 70 50 81 51 85 51 / 70 30 20 10 0 0
Sandpoint 70 49 73 48 78 47 / 50 30 40 20 10 10
Kellogg 71 53 71 54 79 54 / 20 20 40 20 10 10
Moses Lake 74 53 84 55 86 55 / 20 10 0 0 0 0
Wenatchee 73 57 83 60 85 60 / 50 20 0 0 0 0
Omak 74 54 83 56 86 57 / 70 30 10 10 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flash Flood Watch through this evening for East Slopes Northern
Cascades-Wenatchee Area.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
909 PM CDT SUN SEP 8 2013
.UPDATE...
REMOVED MENTION OF THUNDERSTORMS FROM THE FORECAST FOR AFTER
MIDNIGHT. MID-LEVEL WARM AIR ADVECTION DRIVING THE CURRENT
PRECIPITATION OVER THE STATE...BUT ONLY SPRINKLES REACHING THE
GROUND OVER THE CWA...WITH REFLECTIVITIES AND RAINFALL AMOUNTS
LOWERING UPSTREAM IN WESTERN WISCONSIN. LITTLE TO NO ELEVATED CAPE
ON LATEST RAP SOUNDINGS AS BETTER ISENTROPIC FORCING MOVES IN
BETWEEN 06Z AND 12Z. EXPECT TO SEE A LITTLE MORE COVERAGE OF LIGHT
RAIN SHOWERS WITH THE ISENTROPIC LIFT...ESPECIALLY OVER SOUTHEAST
WISCONSIN...BUT ONLY A SLIGHT CHANCE OF MEASURABLE.
&&
.AVIATION/06Z TAFS/...COMING LATER.
&&
.MARINE...WINDS AND WAVES LOWERED BELOW CRITERIA SO SMALL CRAFT
WAS ALLOWED TO EXPIRE. WILL REMOVE MENTION OF THUNDER FROM
NEARSHORE FORECAST.
&&
.FIRE WEATHER...
A HOT AIR MASS MOVING INTO THE REGION WILL RAISE HEAT INDEX VALUES
TO THE MID-UPPER 90S MONDAY AFTERNOON. SOUTH WINDS WILL RISE TO
10 TO 20 MPH...WITH MINIMUM RELATIVE HUMIDITY VALUES LOWERING TO
AROUND 40 PERCENT BY LATE MONDAY AFTERNOON IN THE WESTERN FORECAST
AREA. THESE CONDITIONS WILL LEAD TO INCREASED FIRE DANGER IN AREAS
WITH DRY FUELS. THE HOT AND DRY AIR MASS WILL REMAIN OVER SOUTHERN
WISCONSIN UNTIL TUESDAY NIGHT WHEN A COLD FRONT IS EXPECTED TO
MOVE THROUGH.
&&
.PREV DISCUSSION... /ISSUED 344 PM CDT SUN SEP 8 2013/
TONIGHT...FORECAST CONFIDENCE...MEDIUM
THE COOL AIRMASS UNDER HIGH PRESSURE OVER THE GREAT LAKES WILL MOVE
EAST TONIGHT AS A LOW PRESSURE SYSTEM DEVELOPING OVER THE NORTHERN
PLAINS APPROACHES WISCONSIN. AREA OF LOW CLOUDS TRAPPED BENEATH A
STRONG INVERSION WILL STAY PUT FOR MUCH OF THE NIGHT. THE AREA OF
HIGHER LOW LEVEL RELATIVE HUMIDITY IN THE MODELS WILL REMAIN
NEARLY STATIONARY BETWEEN THE TWO SYSTEMS DURING THIS TIME OF
TRANSITION. THUS...KEPT MIN TEMPS ON THE WARMER SIDE OF GUIDANCE.
WARM AIR ADVECTION ALOFT WILL BEGIN OVER SOUTHERN WI 06-09Z TONIGHT.
THERE ARE ALSO SUBTLE HINTS OF 850/700MB MOISTURE CONVERGENCE AND
INCREASING 700MB RH. ELEVATED CAPE VALUES INCREASE UP TO 1200 J/KG
BY SUNRISE. THUS KEPT THE SLIGHT CHANCE OF THUNDERSTORMS IN THE
FORECAST. LOW/MID LEVEL WIND FIELD WILL BE WEAK...AS THE STRONGER
LOW LEVEL JET WILL BE WELL TO THE NORTH AND WEST TOWARD NORTHERN MN
AND UPPER MICHIGAN. MAIN THREAT FOR ANY ISOLATED THUNDERSTORMS WILL
BE IN NORTHEAST HALF OF MKX FORECAST AREA.
MONDAY...FORECAST CONFIDENCE...HIGH
LEFTOVER MORNING CLOUDS WILL SCOUR OUT FROM SOUTHWEST TO NORTHEAST
THROUGH MIDDAY. ONCE THE SUN PEEKS OUT...925MB TEMPS WARMING INTO
THE UPPER 20C-AROUND 30C SUPPORT TEMPS IN THE MID 90S. LEANED TOWARD
THE STEADY ECMWF FOR MAX TEMP GUIDANCE. WINDS WILL BE INCREASING OUT
OF THE SOUTH...BUT NOT EXPECTING GUSTS HIGHER THAN 20 MPH OR SO.
DEWPOINT TEMPS SHOULD MIX OUT A LITTLE IN THE AFTERNOON...SO PEAK
HEAT INDEX VALUES EXPECTED IN THE MID/UPPER 90S.
MONDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE...MEDIUM
SOUTHWEST WINDS WILL PERSIST AHEAD OF AN APPROACHING COLD FRONT
MONDAY NIGHT...KEEPING LOW TEMPS QUITE MILD FOR SEPTEMBER. THE
FRONT WILL DRAW CLOSER TUESDAY...WITH A FEW SHOWERS/STORMS
POSSIBLE BY LATE AFTERNOON. SHOULD GET PRETTY WARM AGAIN WITH
UPPER 80S AND LOW 90S...THE WARMEST SOUTHEAST.
MAIN CHANCE FOR SHOWERS AND STORMS LOOKS TO BE DURING THE EVENING
AND OVERNIGHT HOURS WITH SHORTWAVE ENERGY MOVING THROUGH ALONG
WITH ADDED UPPER SUPPORT FROM RIGHT ENTRANCE REGION OF JET. ENOUGH
AGREEMENT AMONG MODELS TO MAINTAIN LIKELY POPS. SOME PRECIP MAY
LINGER INTO WEDNESDAY MORNING...BUT DRIER AIR SHOULD BRING AN END
TO CHANCES BY LATE MORNING OR AFTERNOON. WARM AIR WILL LINGER IN
THE AREA WEDNESDAY...WITH HIGHS COOLER THAN TUESDAY...BUT STILL
ABOVE NORMAL FOR THIS TIME OF THE YEAR.
THURSDAY THROUGH SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
HIGH PRESSURE WILL MOVE IN AND REMAIN IN PLACE FOR THE SECOND HALF
OF THE WEEK. THE HIGH WILL BRING A MUCH COOLER AIRMASS TO THE
AREA...WITH HIGHS BY FRIDAY STRUGGLING INTO THE LOW OR MID 60S.
WITH MOSTLY SUNNY SKIES EXPECTED EACH DAY THOUGH...SHOULD BE A
NICE STRETCH OF FALL-LIKE WEATHER.
AVIATION/00Z TAFS/...
MVFR CIGS ARE SPORADICALLY LIFTING TO VFR IN A FEW LOCATIONS.
EXPECTING THESE TO DROP BACK DOWN TO MVFR AFTER DARK. DRY AIR OVER
LAKE MICHIGAN IS FINALLY MAKING IT ONSHORE TO MKE...SO EXPECT
IMPROVEMENT THERE UNTIL LATER IN THE EVENING.
SOUTHERN WI WILL BE STUCK IN A BAND OF MOIST AIR ALL NIGHT...SO
EXPECT MVFR CIGS TO PERSIST. ALL MODELS ARE POINTING TO FOG
POTENTIAL LATE TONIGHT WITH MVFR VSBY. ALSO THERE WILL BE A SMALL
CHANCE OF THUNDERSTORMS OVERNIGHT WITH UPPER LEVEL INSTABILITY AS A
WARM FRONT APPROACHES.
WARM AND DRY AIR WILL PUSH INTO SOUTHERN WI MIDDAY MONDAY AND CLEAR
OUT THE LOW CLOUD DECK.
MARINE...
EAST WINDS OF 10 TO 20 KNOTS WAVES TO BUILD TO SMALL CRAFT ADVISORY
CRITERIA EARLIER TODAY. WAVES WILL GRADUALLY SUBSIDE BELOW SMALL
CRAFT LEVELS BY EARLY EVENING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...REM
TONIGHT/MONDAY AND AVIATION/MARINE...MRC
MONDAY NIGHT THROUGH SUNDAY...DDV
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1103 AM CDT SAT SEP 7 2013
.UPDATE...
MOIST AXIS WITH PRECIPITABLE WATER VALUES OF 1.8 ON RAP ANALYSIS AND
ON THE NOSE OF THE 850MB MOISTURE TRANSPORT AND THETA-E ADVECTION
ARE CENTERED RIGHT OVER CENTRAL AND SOUTH CENTRAL WISCONSIN THIS
MORNING. A CLUSTER OF THUNDERSTORMS IS MOVING ACROSS FOND DU LAC AND
SHEBOYGAN COUNTIES LATE THIS MORNING. THERE IS POTENTIAL FOR THE
STRONGER CORES TO PRODUCE SMALL HAIL WITH THIS ELEVATED
CONVECTION...WITH ELEVATED CAPE OF 700-1000 J/KG.
MESOSCALE MODELS ARE SUGGESTING CONVECTION TO DEVELOP THIS AFTERNOON
OVER SOUTHERN WI AHEAD OF THE SURFACE FRONT. THE FORECAST ISSUE
IS WHETHER OR NOT THE SURFACE AND UPPER LEVEL SUPPORT WILL COME IN
LINE TOGETHER TO PRODUCE ORGANIZED CONVECTION. IT IS NOT LOOKING
LIKE ALL FACTORS WILL BE LINED UP AT THE SAME TIME. IN ADDITION TO
AN ACCELERATING SURFACE FRONT...THERE WILL BE UPPER LEVEL SUPPORT
FROM A WEAK SHORTWAVE...PERSISTENT LOW LEVEL JET/MOISTURE TRANSPORT
AND SUBTLE RIGHT ENTRANCE REGION OF AN UPPER JET.
TIMING IS AN ISSUE AS WELL...WITH THE NAM SHOWING BETTER POTENTIAL
FOR EARLY CONVECTION AND THE HRRR BEGINNING MID AFTERNOON...AND THE
WRF-ARW MODELS SHOWING LATE AFTERNOON/EVENING. COVERAGE WILL BE
SPOTTY...BUT WILL PROBABLY NEED TO RAISE THE POPS A BIT. SPC
CONTINUES TO HAVE A SEE TEXT AREA FOR A FEW THUNDERSTORMS TO
POTENTIALLY BECOME SEVERE WITH WINDS/HAIL DURING THE AFTERNOON.
GUSTY NORTHEAST WINDS IN THE WAKE OF THE COLD FRONT WILL WORK DOWN
THE LAKE THIS EVENING. DELAYED COLD AIR ADVECTION WILL LEAD TO LOW
CLOUDS SPREADING INLAND...PROBABLY THROUGH MADISON...EARLY SUNDAY
MORNING. THESE WOULD GRADUALLY RISE AND MIX OUT SUNDAY AFTERNOON.
&&
.AVIATION/18Z TAFS/...
ISOLATED SHOWERS WITH A FEW ELEVATED THUNDERSTORMS WILL BE POSSIBLE
THROUGH THE MORNING. A CLUSTER OF STRONGER THUNDERSTORMS LOCATED
NEAR FOND DU LAC AND OSHKOSH AT 1030 WILL MOVE SOUTHEAST THROUGH
SHEBOYGAN THROUGH NOON TODAY.
SCATTERED THUNDERSTORMS ARE EXPECTED IN THE VICINITY OF A COLD FRONT
SLOWLY DROPPING DOWN THROUGH SOUTHERN WI THIS AFTERNOON AND EVENING.
ANY STRONGER STORMS COULD PRODUCE SMALL HAIL AND GUSTY WINDS.
SOME MVFR CLOUDS POSSIBLE BEHIND THE FRONT LATER TONIGHT INTO SUNDAY
MORNING IN THE WAKE OF THE COLD FRONT. THESE WILL GRADUALLY RISE TO
VFR AND SCATTER OUT SUNDAY AFTERNOON. GUSTY NORTHEAST TO EAST WINDS
EXPECTED LATE TONIGHT/SUNDAY MORNING...ESPECIALLY NEAR THE
LAKESHORE.
&&
.MARINE...
SOUTHWEST WINDS AHEAD OF A COLD FRONT THROUGH EARLY AFTERNOON. A
COLD FRONT WILL THEN DROP SOUTH LATE THIS AFTERNOON AND EVENING.
NORTHEAST WINDS WILL RAPIDLY INCREASE FROM MID TO LATE EVENING NORTH
TO SOUTH BEHIND THE FRONT. WIND GUSTS AND SUBSEQUENT WAVES ARE
EXPECTED TO REACH SMALL CRAFT ADVISORY CRITERIA LATE TONIGHT THROUGH
SUNDAY AFTERNOON...WITH GRADUAL IMPROVEMENT SUNDAY EVENING.
&&
.PREV DISCUSSION... /ISSUED 312 AM CDT SAT SEP 7 2013/
SHORT TERM...
TODAY AND TONIGHT-FORECAST CONFIDENCE MEDIUM TO HIGH.
THE UPPER LEVEL WEST/NORTHWEST FLOW ACROSS THE GREAT LAKES WILL
BECOME MORE NORTHWEST AS A JET MAX INCREASES TO AROUND 95 KNOTS OVER
THE EASTERN LAKE SUPERIOR AREA THIS AFTERNOON...BEFORE DROPPING INTO
LOWER MICHIGAN TONIGHT. AT 500 MB A WEAK SHORTWAVE WILL DROP
SOUTHEAST ACROSS SOUTHERN WISCONSIN THIS MORNING AND EXIT INTO
NORTHERN INDIANA THIS AFTERNOON. THE 850/700 MB FLOW IS WEAK AS IS
THE MOISTURE CONVERGENCE/UPWARD MOTION.
THE SURFACE COLD FRONT SHOULD ENTER SOUTHERN WISCONSIN DURING THE
EARLY AFTERNOON BEFORE EXITING THE FAR SOUTH TOWARD EVENING.
ZERO TO 1 KM CAPE VALUES INCREASE TO AROUND 2500 J/KG BUT THIS IS
MAINLY POST FRONTAL OVER PORTIONS OF SOUTH CENTRAL WISCONSIN.
ALL IN ALL THERE ARE SEVERAL MECHANISMS FOR SHOWER/THUNDERSTORM
POTENTIAL...BUT THEY DO NOT ALL COME TOGETHER AT ONE TIME.
THEREFORE A BROAD WINDOW OF LOW POPS APPEAR TO BE THE BEST COURSE OF
ACTION. SPC CONTINUES TO HAVE A SEE TEXT AREA FOR A FEW
THUNDERSTORMS TO POTENTIALLY BECOME SEVERE WITH WINDS/HAIL. THIS
WOULD OCCUR DURING THE AFTERNOON.
SUNDAY-FORECAST CONFIDENCE HIGH
SURFACE HIGH MOVES OUT OF ONTARIO INTO MICHIGAN WITH COOL AND DRY
EASTERLY FLOW. UPPER RIDGE REMAINS ANCHORED OVER KANSAS WITH
NORTHWEST FLOW PERSISTING OVER SOUTHERN WISCONSIN.
MONDAY-FORECAST CONFIDENCE HIGH
UPPER TROUGH CURRENTLY OVER PACIFIC NORTHWEST MOVES ACROSS DAKOTAS
DURING THE DAY AND INTO MINNESOTA AT NIGHT. THIS FLATTENS UPPER
RIDGE WHICH SHIFTS TO THE EAST AND FLOW TURNS TO WESTERLY AND
EVENTUALLY SOUTHWEST OVER WISCONSIN. SURFACE LOW OF AROUND 1000 MB
MOVES OUT OF DAKOTAS INTO MINNESOTA BY THE EVENING AND THEN CROSSES
LAKE SUPERIOR OVERNIGHT.
MODELS SHOW NOSE OF LOW LEVEL JET AND SIGNIFICANT WARM ADVECTION
REGIME STAYING WELL NORTH OF THE AREA WITH THUNDERSTORMS NOW EVEN
FURTHER NORTH THAN MODELS DEPICTED 24 HOURS AGO. LOOKS LIKE BULK OF
ACTIVITY WILL BE IN LAKE SUPERIOR AREA AND NORTHWEST ONTARIO. 500 MB
HEIGHTS ACTUALLY RISE 10-20 METERS OVER SOUTHERN WISCONSIN.
LONG TERM...
TUESDAY-FORECAST CONFIDENCE HIGH
SURFACE LOW MOVES ACROSS ONTARIO AND INTO QUEBEC WITH FRONT SLOWING
DOWN AS IT SAGS SOUTH THROUGH SOUTHERN WISCONSIN IN THE AFTERNOON.
GFS IS ONE OF THE SLOWER SOLUTIONS AND HAS 925 MB TEMPS AROUND
+28C...SUGGESTING MID TO UPPER 90S. BOTH NAM AND GFS HAVE PLUME OF
WARM AND DRY AIR JUST AHEAD OF FRONT SPREADING OUT OF THE CENTRAL
PLAINS WHERE IT HAS BEEN RATHER HOT OF LATE AND THERE IS THE
POTENTIAL THAT CURRENT FORECAST IN THE LOWER 90S IS CONSERVATIVE.
LAST TWO RUNS OF ECMWF HAVE FRONT MAKING IT THROUGH FASTER...WHICH
SUGGESTS MORE CONSERVATIVE TEMPERATURE FORECAST IS IN ORDER.
GFS ECMWF AND GEMNH ARE IN RATHER GOOD AGREEMENT IN NARROW PLUME OF
MOISTURE JUST BEHIND THE SURFACE FRONT WITH MOISTURE ADVECTING OUT
OF SOUTHWESTERN STATES. LOOKS LIKE MOST OF THIS CONVECTIVE ACTIVITY
WOULD BE AT NIGHT WHEN MODEST HEIGHT FALLS OF ABOUT 20 METERS
OCCUR.
WEDNESDAY-FORECAST CONFIDENCE HIGH
FRONT PUSHES WELL SOUTH BUT A SECOND REINFORCING COOL SURGE IS SHOWN
TO COME DOWN AS A BROAD UPPER TROUGH DEVELOPS OVER CENTRAL AND
EASTERN CANADA. STRONGEST HEIGHT FALLS OF ABOUT 100 METERS MOVE
ACROSS NORTHERN MICHIGAN WITH STRONGER DYNAMICS JUST BRUSHING
SOUTHERN WISCONSIN. SHOULD BE DRY WITH TEMPERATURES RETURNING MORE
TOWARD SEASONABLE LEVELS.
THURSDAY-FORECAST CONFIDENCE HIGH
MODELS HAVE COME INTO BETTER AGREEMENT IN DIGGING ANOTHER TROUGH IN
NORTHWEST FLOW INTO THE GREAT LAKES. THIS FEATURE IS NOT AS
AMPLIFIED AS ECMWF DEPICTED A FEW RUNS AGO...BUT WOULD CONTINUE TO
PUSH COOLER AIR INTO GREAT LAKES. IN FACT GFS DROPS 850 MB TEMPS
DOWN INTO ABOUT +6C WHICH WOULD BE LOW ENOUGH FOR LAKE EFFECT
SHOWERS. HOWEVER THE FETCH WOULD LIKELY KEEP THEM OFFSHORE.
FRIDAY-FORECAST CONFIDENCE HIGH
DRY AND COOL NORTHWEST FLOW ALOFT SHOULD CONTINUE WITH LARGE SURFACE
HIGH OVER MICHIGAN AND LIGHT SURFACE FLOW.
AVIATION/12Z TAFS/...
MAINLY VFR CONDITIONS. A MID LEVEL CLOUD DECK WILL DROP INTO
SOUTHERN WISCONSIN EARLY THIS MORNING WITH ISOLATED SHOWERS WITH
A FEW ELEVATED THUNDERSTORMS. THEN SCATTERED THUNDERSTORMS
ARE EXPECTED IN THE VICINITY OF A COLD FRONT SLOWLY DROPPING DOWN
THROUGH SOUTHERN WI THIS AFTERNOON AND EVENING.
SOME MVFR CLOUDS POSSIBLE BEHIND THE FRONT LATER TONIGHT INTO SUNDAY
MORNING.
MARINE...
SOUTHWEST WINDS AHEAD OF A COLD FRONT THIS MORNING. A COLD FRONT
WILL THEN DROP SOUTH THIS AFTERNOON. NORTHEAST WINDS WILL INCREASE
TONIGHT BEHIND THE FRONT. WINDS/WAVES MAY REACH SMALL CRAFT
ADVISORY CRITERIA LATE TONIGHT AND INTO SUNDAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 1 AM TO 7 PM CDT SUNDAY FOR LMZ645-646.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 PM CDT SUNDAY
FOR LMZ643-644.
&&
$$
UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
SUNDAY THROUGH FRIDAY...CRAVEN
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1004 PM MDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 1004 PM MDT SUN SEP 8 2013
RAP/NAM MODELS CONTINUE TO FOCUS THE HEAVIEST RAINFALL FROM EAST
CENTRAL UTAH TO NORTHWEST COLORADO DURING THE NEXT 12-24
HOURS...ASSOCIATED WITH THE SHEAR AXIS THAT CUTS ACROSS THE SAME
AREA. THIS REMAINS REASONABLE AS SHORT WAVE ENERGY MOVES INTO SRN
UTAH AND SHEARS NORTHEAST. THUS FAR...RAINFALL AMOUNTS HAVE BEEN
"MELLOW" (MOSTLY LESS THAN A QUARTER INCH) EXCEPT FOR CRAIG THAT
HAD A PULSE STORM THAT PRODUCED A HEAVY SHOWER. HOWEVER THIS IS A
SCENARIO WHERE VALUES INCREASE STEADILY AND THE WIDESPREAD NATURE
OF THESE SHOWERS WILL CAUSE ENHANCED FLOWS IN NORMALLY DRY WASHES
AND MOUNTAIN STREAMS. ONE AREA OF CONCERN IS SALT WASH CREEK THAT
FLOWS INTO WOLFE RANCH IN ARCHES NATIONAL PARK.
MONDAY...THE POTENTIAL FOR SIGNIFICANT RAINS SPREADS EAST INTO
THE WESTERN COLORADO MOUNTAINS. THE RAIN COOLED AIR MASS LIMITS
CONVECTIVE POTENTIAL AND HEAVY SHOWER POTENTIAL...BELIEVE THE MAIN
"FLOODING" THREAT WILL BE ENHANCED FLOWS IN DRY WASHES AND STREAMS
AND ROCK/MUD SLIDES. BOOSTED POP/QPF GRIDS TO REFLECT THE LATEST
GUIDANCE AND TRENDS.
UPDATE ISSUED AT 637 PM MDT SUN SEP 8 2013
THE FEATURE TO WATCH FOR THE NEXT 6-12 HOURS IS THE VORT CENTER
STREAMING NORTHWARD OVER NE ARIZONA. AS THIS VORT CENTER MOVES
INTO ERN UTAH LATER TONIGHT...DEFORMATION AXIS BETWEEN DEEP
SUBTROPICAL PLUME ATTACHES ITSELF WITH THE NRN STREAM MONTANA
SHORT WAVE. IN THE RAP MODEL...QPF AMOUNTS ACROSS EAST CENTRAL
UTAH INTO NORTHWEST COLORADO IS SIGNIFICANT WITH SOME AREAS
EXCEEDING AN INCH. THE MOST NOTABLE IS OVER THE TAVAPUTS WITH OVER
3 INCHES OF RAIN. FORECASTING QPF IS TRICKY AND NOT SURE HOW MUCH
IS ATTRIBUTED TO CONVECTIVE PROCESSES WITH THE MODEL. PRUDENT TO
WATCH OBSERVATIONAL TRENDS THIS EVENING.
&&
.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 351 PM MDT SUN SEP 8 2013
H5 HAND ANALYSIS CENTERED THE SUB-TROPICAL RIDGE OVER THE EASTERN
PLAINS OF KANSAS. UPSTREAM A STRONGER LOW PRESSURE CIRCULATION WAS
CENTERED NEAR THE PANHANDLE OF IDAHO. THE BEST HEIGHT FALLS REMAIN
EAST OF THE LOW AND THE MODEL FORECASTS OF TRACKING THIS FEATURE
ALONG THE US/CANADIAN BORDER OVER THE NEXT 24 TO 48 HOURS LOOKS ON
TRACK. A MORE DIFFUSE...BUT IMPORTANT CIRCULATION CAN ALSO BE SEEN
SPINNING NEAR THE SOCAL/AZ BORDER. THE GRADIENT BETWEEN THE
WESTERN TROUGHS AND EASTERN RIDGE IS PROVIDING A PERSISTENT FETCH
OF DEEP MONSOONAL MOISTURE INTO WESTERN COLORADO AND EASTERN UTAH.
GOES DERIVED IMAGERY SHOWS AN IMPRESSIVE RING OF PWAT EXTENDING
FROM THE HIGH COUNTRY OF MEXICO INTO THE GREAT BASIN...NORTHERN
PLAINS AND BACK INTO THE MO RIVER VALLEY. PWATS ARE GENERALLY 175
- 200 PERCENT OF NORMAL IN THIS RING INCLUDING KGJT.
DYNAMICS...THERMAL INSTABILITY AND THIS MOISTURE BE PRESENT FOR
THE FIRST PART OF THE WEEK OVER OUR CWA WHICH WILL LEAD TO A WET
FORECAST FOR MANY AREAS. TEMPERATURES WILL BE LIMITED BY THE
PRECIPITATION AND CLOUDS AND WILL END UP BELOW NORMAL TO START OUT
THE WEEK.
THE CONVECTION IN OUR CWA IS MOST PROLIFIC NEAR THE THICKER CLOUD
INTERFACE FROM EARLIER TODAY. THESE STORMS ARE MOVING NORTHWARD
AROUND 25 MPH AND SO FAR THE THREAT OF FLOODING OUTSIDE THE WATCH IS
MINIMAL. MORE ORGANIZED CONVECTION IS LOCATED OVER SOUTH CENTRAL UTAH
AND NORTHERN ARIZONA. THIS IS ASSOCIATED WITH ENERGY FROM THE
SOUTHERN LOW AND AN UPPER JET MAXIMA EXTENDING NORTHEAST INTO
WESTERN WYOMING AHEAD OF THE APPROACHING NORTHERN TROF. THIS AREA OF
ENHANCED ASCENT WILL BE SHIFTING EASTWARD THIS EVENING AND
OVERNIGHT. THE MOISTURE PLUME WILL BE SQUEEZED INTO OUR CWA WITH
PWATS LOOKING TO SPIKE AT 1.2-1.4 INCHES NEAR THE UTAH/CO BORDER.
LIFT ASSOCIATED WITH A DEFORMATION/SHEAR AXIS BETWEEN THE TROF AND
THE RIGHT ENTRANCE REGION OF THE UPPER JET ALL LOOK TO BRING
DECENT PRECIPITATION CHANCES TO EASTERN UTAH AND NORTHWEST
COLORADO THROUGH SUNRISE. ISOLATED THUNDERSTORMS WILL BE EMBEDDED
IN THE PRECIPITATION PROVIDING AN HEAVY RAIN THREAT. HOWEVER WITH
A DEEP WARM CLOUD LAYER EVEN THE SHALLOW CONVECTION SHOULD BE
EFFICIENT AT MAKING RAIN.
CONFIDENCE NOT QUITE HIGH ENOUGH TO EXPAND WATCH EAST OR NORTHWARD
INTO TOMORROW. THE PLUME LOOKS TO BE CENTERED FROM THE FOUR CORNERS
TO THE NORTHERN MOUNTAINS BY TOMORROW AFTERNOON...THE NORTHERN END
ARCING WESTWARD BY THE PULL OF THE NORTHERN STREAM TROF MOVING INTO
THE WESTERN DAKOTAS. THIS PLUME LEAVES A THICK CLOUD LAYER OVER MUCH
OF THE CWA...AND SHOULD HELP LIMIT DEEP CONVECTION THROUGH EARLY
AFTERNOON. DRIER AIR LOOKS TO FILTER INTO THE FAR NORTHWEST CWA
BEHIND THE TROF AND MODELS INSIST ON LIMITING THE CONVECTION HERE.
WHILE IN THE 4 CORNERS REGION...ASCENT REMAINS STRONG IN THE
MOISTURE PLUME AS MODELS SHOW ENERGY ARRIVING BY PEAK HEATING TO
HELP BLOSSOM THE CONVECTION. AGAIN EXPECT ANOTHER ROUND OF LATE
NIGHT PRECIPITATION TO LINGER INTO TUESDAY MORNING FAVORED FROM
SOUTHEAST UTAH INTO THE CENTRAL MOUNTAINS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 351 PM MDT SUN SEP 8 2013
THE SUBTROPICAL MOISTURE PLUME WILL CONTINUE TO STREAM DIRECTLY
OVER THE FORECAST AREA AS THE PATTERN BECOMES BLOCKED OVER THE
WESTERN CONUS. THE FIRST SHORTWAVE WILL HAVE MOVED INTO THE
NORTHERN PLAINS BY TUE MORNING...WITH A HIGH PRESSURE RIDGE
REPLACING IT OVER THE PACIFIC NORTHWEST. AS THE NORTHERN BRANCH
SHORTWAVE CONTINUES EAST ON TUE...LOW PRESSURE WILL LINGER OVER
THE DESERT SOUTHWEST AND GREAT BASIN. THE NORTHWEST HIGH AND
SOUTHWEST LOW WILL FORM A REX BLOCK OF SORTS THAT WILL GRADUALLY
EVOLVE BY THE END OF THE WEEK. THE HIGH IS PROGGED TO WEAKEN AND
SHIFT EAST...FORMING A STRONG RIDGE TO OUR EAST...STILL KEEPING A
BLOCK-ISH PATTERN. THE GFS IS QUICKEST IN MOVING OUT THE SOUTHWEST
LOW LATE IN THE WORK WEEK. HOWEVER NATIONAL DISCUSSIONS PREFER A
SLOWER SOLUTION. WITH A SOUTHWEST LOW IN PLACE FOR MOST OF THE
LATE SUMMER...I PREFER THE SLOWER SOLUTION AS WELL. THEREFORE WILL
GENERALLY FOLLOW THE ECMWF FOR THIS FORECAST.
THAT SAID...MADE FEW CHANGES TO THE FORECAST. THE LARGER SCALE
PATTERN AS DESCRIBED ABOVE KEEPS THE THE MOISTURE PLUME PRETTY
MUCH OVERHEAD. THERE ARE SOME NUANCES THOUGH THAT MAY DETERMINE
JUST HOW WET WE WILL REMAIN. ON TUE/TUE NIGHT...THE UPPER LOW
CENTER IS PROGGED TO MOVE NORTHWARD FROM SOUTHWEST AZ TO THE
AZ/NV/UT TRIPLE POINT. AT THE LOWER LEVELS...THE RESULTING
EASTERLY FLOW OVER OUR FORECAST AREA CAN HAVE A SUPPRESSING
INFLUENCE ON PRECIPITATION. HOWEVER DEEP MOISTURE WILL CONTINUE TO
BE IN PLACE. AND WITH THE LOW JUST TO OUR WEST...WE SHOULD SEE
SOME ENHANCED INSTABILITY DUE TO ITS PROXIMITY. THEN ACCORDING TO
THE EC...THE LOW STALLS OVER SOUTHWEST UT THROUGH THE END OF THE
WEEK. MODELS INDICATE THAT A WAVE WILL ROTATE OFF THE LOW AND
SWEEP OVER OUR NORTHWEST CORNER ON WED OR THU. CONFIDENCE IN THE
DETAILS IS LACKING ON THIS FEATURE...BUT STILL KEPT POPS
RELATIVELY HIGH. A SLIGHT DRYING IS PROGGED BY LATE IN THE
WEEK...AND BY EARLY NEXT WEEK EVEN THE EC MOVES THE LOW TO THE
NORTHEAST.
TEMPERATURES WILL REMAIN ON THE COOL SIDE...ESPECIALLY COMPARED
TO THE VERY WARM CONDITIONS WE HAVE SEEN RECENTLY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1004 PM MDT SUN SEP 8 2013
WIDESPREAD -SHRA WITH LOCAL VIS BLO 3SM +SHRA BR DURING THE NEXT
24 HOURS. AREAS OF IFR CIGS/VIS AT MOUNTAIN TAF SITES AND
AIRFIELDS. MOUNTAIN TOPS WILL BE FREQUENTLY OBSCURED. ISOLATED
THUNDERSTORMS NORTH IF I-70 WITH SCATTERED THUNDERSTORMS
SOUTH...WITH ANY THUNDERSTORMS HAVING THE POTENTIAL PRODUCING
HEAVY RAIN SHOWERS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR COZ020-021.
UT...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR UTZ022-025-027>029.
&&
$$
UPDATE...PF
SHORT TERM...15
LONG TERM...EH
AVIATION...PF
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
450 AM EDT MON SEP 9 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS UPPER LEVEL RIDGING
EXPANDING EASTWARD FROM THE MIDDLE AND SOUTHERN MS VALLEY TOWARD THE
SE CONUS...WHILE DOWNSTREAM TROUGHING EXTENDS SOUTHWARD TO THE
BAHAMAS FROM JUST OFF THE EASTERN SEABOARD. DEEP LAYER NORTHERLY
FLOW SEEN IN THE KJAX 00Z SOUNDING PROFILE IS DRIVING A LARGE AREA
OF UPPER LEVEL SUBSIDENCE / DRY AIR SOUTHWARD INTO THE FLORIDA
PENINSULA. THE DRY AIR IS NOW ENTRENCHED OVER ABOUT THE ENTIRE
FORECAST AREA...WITH DEEPER MOISTURE SHOVED SOUTH OF EVEN FT MYERS
THIS EARLY MORNING. THE PW VALUE OF THE 00Z SOUNDING AT KTBW WAS
AROUND 1.5" WHICH IS ABOUT AT THE 25TH PERCENTILE OF VALUES FOR
EARLY TO MID SEPTEMBER. THIS LOW VALUE IS REPRESENTATIVE OF THE
DEPTH AND STRENGTH OF THE DRY AIR ALOFT. SHOWER AND THUNDERSTORM
ACTIVITY WILL CONTINUE TO RESPOND TO THIS HOSTILE ENVIRONMENT WITH
LOWER AREAL COVERAGE AND SHORTER CONVECTIVE LIFE-CYCLES.
AT THE SURFACE...A LARGE AREA OF RIDGING EXTENDS DOWN ACROSS THE
EASTERN CONUS TO THE NORTHERN GULF OF MEXICO. OUR POSITION ON THE
SOUTHERN PERIPHERY OF THIS RIDGE IS PROVIDING A LOW LEVEL NE TO E
FLOW PATTERN. REGIONAL RADARS ARE FAIRLY QUIET THIS MORNING OTHER
THAN JUST A FEW ISOLATED CELLS WELL OFFSHORE ALONG THE WESTWARD
PROPAGATING LAND BREEZE BOUNDARY. SIMILAR TO SUNDAY
MORNING...LOWER DEWPOINTS ARE ALLOWING TEMPS TO DROP INTO THE
MID/UPPER 60S FOR NORMALLY COOLER LOCATIONS OF THE NATURE COAST.
JUST A TASTE OF FALL?
WITH THE DRY AIR ALOFT AND GENERAL SYNOPTIC SUPPRESSION...SKIES ARE
MOSTLY CLEAR THIS MORNING...AND WILL REMAIN SO FOR SEVERAL MORE
HOURS UNTIL DIURNAL HEATING CAN BEGIN TO BUBBLE UP A SCT SHALLOW CU
FIELD AFTER 10-11AM.
&&
.SHORT TERM (TODAY THROUGH WEDNESDAY)...
TODAY/TONIGHT...
THE MAIN WEATHER STORY REMAINS THE DRY AIR ALOFT AND ITS INFLUENCE
ON THE DIURNAL CONVECTION. THE DRY AIR ON SUNDAY PREVENTED ALMOST
ALL CONVECTION OVER THE NORTHERN HALF OF THE AREA...AND HAS
PENETRATED EVEN FURTHER SOUTH FOR TODAY. THE MORNING HOURS WILL BE
VERY PLEASANT FOR EARLY SEPTEMBER WITH DRY CONDITIONS UNDER MOSTLY
SUNNY SKIES. SIMILAR TO SUNDAY...THERE IS A SHALLOW MOISTURE LAYER
TRAPPED UNDERNEATH THE DRY AIR...AND DIURNAL HEATING WILL INTERACT
TO BUBBLE UP A SCT SHALLOW CU FIELD BY THE EARLY AFTERNOON.
THE DEEPEST LAYER OF HOSTILE MID LEVEL AIR WILL EXIST OVER THE
CENTRAL AND NORTHERN ZONES ASSOCIATED WITH WHAT THE GFS IS
ADVERTISING AS SOME HEALTHY Q-VECTOR DIVERGENCE AND OVERALL SYNOPTIC
SUPPRESSION. THIS ENVIRONMENT SHOULD SUPPORT ISOLATED STORMS AT
BEST...AND ANY STORMS THAT DO DEVELOP WILL BE SHORT-LIVED AS THEY
QUICKLY INGEST THE HOSTILE MID-LEVEL THETA-E AIR INTO THEIR
CONVECTIVE COLUMNS. SOUTH OF TAMPA BAY ALONG THE SUNCOAST AND
INTERIOR SOUTH-CENTRAL ZONES...THE DRY AIR IS STILL IN PLACE...BUT
NOT QUITE AS DEEP. THE SOUTHERN COASTAL ZONES WILL ALSO SEE THE MOST
DEFINED EASTERLY FLOW TO FOCUS LOW LEVEL CONVERGENCE ALONG THE I-75
CORRIDOR THIS AFTERNOON. IF THE FLOW WAS NOT EASTERLY...THEN WOULD
PROB GO 20-30% ON THE RAIN CHANCES AT BEST...BUT GIVEN THE FAVORABLE
WIND DIRECTION WHICH USUALLY GIVES QUITE HIGH RAIN CHANCES...WILL
FORECAST (30-40%). THESE NUMBERS ARE ABOVE THE STATISTICAL
GUIDANCE...BUT WELL BELOW THE CLIMO RAIN CHANCES FOR THE PARTICULAR
LOW LEVEL WIND REGIME.
ANY WIDELY SCT EVENING STORMS WILL QUICKLY EXIT OUT OVER THE COASTAL
WATERS BY 02-03Z. GRADIENT BEGINS TO TIGHTEN SOMEWHAT OVERNIGHT AS
THE RIDGE TO OUR NORTH DROPS SOUTH AND STRENGTHENS. THE INFLUENCE OF
THIS WILL MAINLY BE FELT OVER THE COASTAL WATERS WITH A NOCTURNAL
EASTERLY WIND SURGE. STILL SEE SOME POTENTIAL TO BRIEFLY DE-COUPLE
OVER THE INTERIOR NATURE COAST BEFORE DAWN. IF THESE AREAS CAN
DE-COUPLE...THEN ANOTHER MORNING WITH LOWS IN THE MID/UPPER 60S IS
LIKELY. WILL HAVE TO WAIT AND SEE IF THE SLIGHT PRESSURE DIFFERENCE
NEAR THE COAST RELATED TO THE NOCTURNAL SURGE WIND SPEED DIVERGENCE
IS ENOUGH TO LOCALLY TIGHTEN THE GRADIENT...AND OVERCOME THE
DE-COUPLING PROCESS. ELSEWHERE FURTHER SOUTH LOWER TO MID 70S WILL
BE COMMON.
TUESDAY/WEDNESDAY...
THE DRY AIR ALOFT IS STILL IN PLACE FOR TUESDAY TO HINDER DEEP
CONVECTION DEVELOPMENT. THE LOW LEVEL FLOW IS DEFINED EASTERLY FOR
ALL ZONES BY THE AFTERNOON HOURS...AND MAY HELP SOMEWHAT TO FOCUS
THE CONVERGENCE. THE FLOW APPEARS TO MUCH TO ALLOW A DEFINED
SEA-BREEZE TO DEVELOP...HOWEVER AT LEAST SOME WEAKENING OF THE
AFTERNOON WINDS ACROSS THE NEAR SHORE WATERS SHOULD ALLOW MODEST
SPEED CONVERGENCE NEAR THE COAST. WITH THIS IN MIND WILL EXPAND THE
30% POPS FOR WIDELY SCT LATE AFTERNOON STORMS NORTHWARD TO MANATEE
COUNTY AND SOUTHERN PORTIONS OF TAMPA BAY. HOWEVER...THIS IS REALLY
JUST A COSMETIC CHANGE TO THE FORECAST...AS ANY STORMS STILL LOOK
"FEW AND FAR BETWEEN". CONVECTION OVER THE NATURE COAST AGAIN LOOKS
ISOLATED AT BEST.
BY WEDNESDAY...A WEAK UPPER LOW FEATURE IS SHOWN BY THE GFS AND
ECMWF TO BEGIN RETROGRADING OVER THE STATE. THIS FEATURE SHOULD
BRING AT LEAST SOME INCREASE IN DEEP LAYER MOISTURE TO CENTRAL AND
SOUTHERN PORTIONS OF THE AREA. CERTAINLY NOT GOING TO MAKE THE
ATMOSPHERE MOIST OVERHEAD...BUT POTENTIALLY NOT QUITE AS HOSTILE TO
DEEP CONVECTION. WILL INCREASE RAIN CHANCES TO 25-35% NORTH AND
35-50% SOUTH. THESE NUMBERS AGREE WELL WITH ECMWF STATISTICAL
GUIDANCE...BUT REMAIN WELL BELOW THE CLIMO RAIN CHANCES ASSOCIATED
WITH EASTERLY FLOW.
&&
.LONG TERM (THURSDAY THROUGH NEXT SUNDAY)...
AN AXIS OF HIGH PRESSURE WILL RESIDE ACROSS THE GULF COASTAL AND
SOUTHEASTERN STATES THU AS A SURFACE TROUGH/TROPICAL WAVE EXITS FL
INTO THE GULF. DURING FRI AND SAT THE SURFACE RIDGE SHIFTS SOUTH/
INTO NORTHERN FL/ IN RESPONSE TO AN UPPER TROUGH WITH A FRONTAL
BOUNDARY THAT SETTLES IN ALONG THE GA/FL LINE. BY SUN THE UPPER
TROUGH MOVES OUT OVER THE ATLANTIC AS IT LIFTS NORTH WITH THE
FRONTAL BOUNDARY DISSIPATING AS HIGH PRESSURE OVER THE EASTERN CONUS
BRIDGES IT.
THE AREA WILL BE UNDER THE INFLUENCE OF EASTERLY FLOW...RELAXED
ENOUGH FOR AFTERNOON SEA BREEZES...WITH ADEQUATE MOISTURE FOR
ISOLATED TO SCATTERED THUNDERSTORMS WITH THE HIGHEST COVERAGE IN THE
AFTERNOONS. THE RAIN CHANCES WILL BE CLOSE TO NORMAL AND GENERALLY
IN THE 30 TO 40/50 PERCENT RANGE...FROM NORTH TO SOUTH.
&&
.MARINE...
LOCAL GRADIENT WILL REMAIN WEAK THROUGH THIS AFTERNOON KEEPING WINDS
AND SEAS LOW. THEREAFTER...HIGH PRESSURE TO OUR NORTH WILL
STRENGTHEN AND PROVIDE FAVORABLE CONDITIONS TO SUPPORT NOCTURNAL AND
MORNING SURGES OF EASTERLY FLOW THAT WILL APPROACH OR REACH
CAUTIONARY LEVELS AT TIMES BEGINNING TONIGHT AND RE-DEVELOPING
TUESDAY NIGHT. THE LOCAL GRADIENT AND RESULTING WINDS WILL AGAIN
RELAX BY THE END OF THE WEEK AS HIGH PRESSURE BUILDS SOUTH OVER THE
EASTERN GULF OF MEXICO.
&&
.AVIATION...
LIMITED AFTERNOON CONVECTION HAS NOW SHIFTED OFFSHORE WITH VFR
PREVAILING FOR THE NEXT 24 HOURS. CAN NOT RULE OUT SOME PATCHY BR
TOWARD SUNRISE AT LAL/PGD BUT WILL LEAVE OUT OF THE TAFS. DRY AIR
MOVING IN MON WITH ONLY VCTS AT PGD/FMY/RSW.
&&
.FIRE WEATHER...
HIGH PRESSURE TO OUR NORTH WILL CONTINUE TO PROVIDE THE REGION WITH
A GENERALLY EASTERLY FLOW THE NEXT SEVERAL DAYS. THE GRADIENT MAY BE
LIGHT ENOUGH TODAY IN ORDER TO ALLOW WINDS TO TURN ONSHORE AT THE
IMMEDIATE COAST IN THE AFTERNOON...HOWEVER FLOW SHOULD THEN BE
STRONG ENOUGH ON TUESDAY AND WEDNESDAY TO PREVENT MUCH OF A
SEA-BREEZE. DRIER LOW LEVEL AIR IS NOW IN PLACE...ESPECIALLY NORTH
OF I-4...HOWEVER EVEN WITH THIS DRIER AIR...RELATIVE HUMIDITY IS
EXPECTED TO REMAIN ABOVE CRITICAL LEVELS. DISPERSION INDICES WILL
HOWEVER BE ON THE HIGH SIDE BOTH THIS AFTERNOON AND TUESDAY
AFTERNOON...WITH THE HIGHEST VALUES TO THE NORTH OF TAMPA BAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 93 75 92 76 / 20 10 20 10
FMY 92 74 92 75 / 40 20 30 20
GIF 92 73 92 73 / 20 10 20 10
SRQ 93 75 92 75 / 20 20 30 20
BKV 93 68 92 69 / 20 10 20 10
SPG 93 78 91 79 / 20 10 20 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
205 AM CDT MON SEP 9 2013
.DISCUSSION...
251 PM CDT
MAIN FORECAST CONCERNS WILL BE TEMPERATURES MONDAY AND TUESDAY AS
HEAT RETURNS TO THE AREA...AS WELL AS PERIODIC CHANCES FOR
THUNDERSTORMS TONIGHT THROUGH EARLY MONDAY...AND AGAIN TUESDAY NIGHT
THROUGH WEDNESDAY NIGHT.
THIS AFTERNOON...A COLD FRONT STRETCHES FROM SOUTH DAKOTA SOUTHEAST
INTO SOUTHERN ILLINOIS. DEW POINTS POOLING INTO THE LOW 70S ALONG THE
FRONTAL BOUNDARY HAVE LED TO MLCAPE AXIS OF 2000-2500 J/KG JUST
SOUTH OF THE CWA...WITH JUST OVER 1000 J/KG INTO THE FAR SOUTHERN
CWA PER SPC MESOANALYSIS. WEAK SURFACE CONVERGENCE ACROSS CENTRAL
ILLINOIS...WEAKLY ENHANCED BY DIFFERENTIAL HEATING BETWEEN THE
THICKER CIRRUS SHIELD TO OUR SOUTH HAS LED TO A FEW SHOWERS AND
THUNDERSTORMS ACROSS THE SOUTHERN CWA. OVER THE NEXT FEW
HOURS...EXPECT THE WIDELY SCATTERED ACTIVITY TO CONTINUE...BUT
SHOULD FADE WITH LOSS OF HEATING THIS EVENING...PROVIDING AT LEAST A
BRIEF DRY WINDOW ACROSS THE CWA.
TONIGHT THROUGH TOMORROW...
CLOSED UPPER LOW CURRENTLY OVER MONTANA IS PROGGED TO MOVE EAST THIS
EVENING AND TONIGHT...WHILE SURFACE LOW OVER THE PLAINS LIFTS
NORTHEAST...DEEPENING SLIGHTLY AS IT MOVES OVER MINNESOTA BY
TOMORROW AFTERNOON. THE FRONTAL BOUNDARY TO OUR SOUTH WILL BEGIN TO
LIFT NORTH ACROSS THE AREA TONIGHT WITH A BAND OF MID LEVEL
ISENTROPIC ASCENT SLOWLY TRANSITIONING WEST TO EAST ACROSS THE
CWA FROM LATE THIS EVENING THROUGH MONDAY MORNING...BRINGING AT
LEAST A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGH THE
OVERNIGHT HOURS. NAM SUGGESTS A SLOWER PROGRESSION OF THIS FEATURE
WITH ASCENT STILL OCCURRING IN THE EASTERN PORTIONS OF THE CWA EARLY
MONDAY AFTERNOON...AT WHICH TIME MODERATE INSTABILITY WILL HAVE
DEVELOPED...WEAKLY CAPPED ON THE LEADING EDGE OF THE EML WHICH WILL
BE ADVECTING EAST INTO THE AREA THROUGH THE DAY. IF THIS PANS
OUT...CONCERNED THAT WE MAY SEE SOME INTENSIFICATION OF ANY SHOWERS
THAT MAY DEVELOP OVERNIGHT AS THEY BECOME ROOTED IN THE BOUNDARY
LAYER LATE TOMORROW MORNING OR EARLY AFTERNOON OVER FAR EAST CENTRAL
ILLINOIS OR NORTHWEST INDIANA. OVERALL CONFIDENCE IN PRECIP IS PRETTY
LOW THOUGH...WITH LACK OF ANY SIGNIFICANT UPPER LEVEL SUPPORT
THROUGH THE PERIOD. IF ANYTHING DID DEVELOP COVERAGE MAY END OF
STAYING PRETTY LOW.
ATTENTION TURNS TO TEMPERATURES TOMORROW AFTERNOON. STOUT CAPPING
INVERSION ADVECTS IN FROM THE WEST AND MODEST DRYING SHOULD ALLOW
SKIES TO CLEAR BEHIND ANY MID LEVEL CLOUDINESS ASSOCIATED WITH THE
WARM FRONT EARLY IN THE DAY. BETWEEN 18Z AND 00Z...H92 TEMPS ARE
EXPECTED TO WARM FROM AROUND 23C TO NEAR 27C...MOVING OFF THE CHARTS
SO TO SPEAK WITH RESPECT TO LOCAL UPPER AIR CLIMATOLOGY. QUITE A BIT
OF VARIANCE IN MODEL PROG SURFACE TEMPERATURES TOMORROW. GFS AND GEM
SHOW LOW TO MID 80S ACROSS THE CWA...WHILE THE NAM AND ECMWF
INDICATE TEMPERATURES SOARING INTO 90S. GIVEN THE EXPECTED WARM
ADVECTION AND CLEARING SKIES...SEE LITTLE SUPPORT FOR THE COOLER
MODELS...AND ENDED UP BUMPING TEMPERATURES A COUPLE DEGREES MONDAY
TOWARDS A BLEND OF THE ECMWF/ECMWFBC...CALLING FOR LOW 90S ACROSS
THE CWA...AND 91/93 AT ORD/RFD RESPECTIVELY.
TUESDAY...
CONTINUE TO LOOK AT NEAR RECORD HIGH TEMPERATURES ON TUESDAY AS WE
SIT SQUARELY UNDER THE THERMAL RIDGE. MODELS IN DECENT AGREEMENT
SHOWING H85 TEMPS BETWEEN 21-22C...AND H92 TEMPS BETWEEN 27-28C...
AGAIN OFF THE CHARTS WITH RESPECT TO LOCAL CLIMATOLOGY. DEEP MIXING
DURING THE DAY SHOULD HELP TO MIX THE DEW POINTS TOWARDS THE UPPER
50S...WHICH WILL HELP TEMPERATURES QUICKLY RESPOND. WITH GREATER
CONFIDENCE THAT WE SHOULD SEE PLENTY OF SUNSHINE...FULLY EXPECT TO
BE FLIRTING WITH IF NOT EXCEEDING RECORD HIGHS ON TUESDAY. SEE
CLIMATE SECTION FOR INFORMATION ON RECORD TEMPS. BLENDED WITH
ECMWF/GEMNH GUIDANCE WHICH TENDS TO VERIFY WELL UNDER A STRONG
THERMAL RIDGE...BUMPING UP TEMPS ABOUT A DEGREE OR SO FROM THE
PREVIOUS FORECAST...AND CALLING FOR TEMPS INTO THE MID 90S ACROSS
THE CWA.
WEDNESDAY...
A COLD FRONT IS EXPECTED TO SAG SOUTH ACROSS THE CWA ON WEDNESDAY.
EXPECT A SPREAD IN HIGH TEMPERATURES NORTH TO SOUTH ACROSS THE CWA
DEPENDING ON FRONTAL TIMING...WITH LOW 80S IN THE NORTH TO LOW 90S
IN THE SOUTH. MODERATE INSTABILITY IS EXPECTED TO DEVELOP JUST AHEAD
OF THE FRONT...WITH THUNDERSTORMS EXPECTED PARTICULARLY DURING THE
AFTERNOON HOURS AIDED BY SURFACE HEATING. OVERALL DYNAMICS WITH THIS
SYSTEM APPEAR PRETTY WEAK...WITH WEAK CONVERGENCE ALONG THE
FRONT...AND THE MAIN UPPER WAVE EXPECTED TO PASS WELL TO THE NORTH.
THIS SHOULD LEAD TO LOWER COVERAGE OF THUNDERSTORMS ALONG THE FRONT.
THURSDAY THROUGH SUNDAY...
STRONG CANADIAN HIGH WILL BUILD SOUTH ACROSS THE AREA PROVIDING A
DRIER PERIOD AS WELL AS COOLER WEATHER. BOTH THE GFS AND ECMWF
ADVERTISE H85 TEMPS FALLING TO AROUND 3C FRIDAY AFTERNOON.
FRIDAY...WHICH SHOULD BE THE COOLEST DAY THE UPCOMING WEEK...WE ARE
LOOKING AT HIGHS ONLY THE THE UPPER 60S NORTH OF I-80...AND AROUND
70 SOUTH. TEMPERATURES SHOULD START TO MODERATE NEXT WEEKEND AS THE
HIGH SHIFTS EAST AND RETURN FLOW SPREADS OVER THE AREA.
DEUBELBEISS
&&
.CLIMATE...
THERE IS A CHANCE THAT RECORD WARM LOWS WILL OCCUR TUESDAY
SEPTEMBER 10TH...AND ALSO SLIGHT CHANCE OF RECORD HIGH TEMPERATURES.
CHICAGO:
RECORD HIGH: 95 (1983)
RECORD WARM LOW: 75 (1912)
ROCKFORD:
RECORD HIGH: 96 (1931)
RECORD WARM LOW: 70 (2000)
TRS/RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* VEERING AND INCREASING WINDS AFTER SUNRISE.
* SLIGHT CHANCE OF MVFR CEILINGS DURING REST OF OVERNIGHT INTO
EARLY MORNING.
TRS
//DISCUSSION...UPDATED 06Z...
A LARGE HIGH CENTERED WELL EAST OF THE REGION WILL CONTINUE TO
SLOWLY MOVE SOUTHEASTWARD TO THE NORTHEASTERN AND NEW ENGLAND
STATES BY DAYBREAK. MEANWHILE...LOW PRESSURE CONTINUED TO DEVELOP
IN THE NORTHERN HIGH PLAINS AS AN UPPER LOW MOVED OVER SOUTHERN
CANADIAN AND THE NORTHERN ROCKIES. THE UPPER LOW IS PROGGED TO
BEGIN TO TRANSITION INTO AN OPEN WAVE AS IT PROGRESSES TO FAR
SOUTHEASTERN SASKATCHEWAN...FAR SOUTHERN MANITOBA AND THE FAR
NORTHERN PLAINS DURING THE DAY. S A RESULT THE ASSOCIATED SURFACE
LOW ALSO PROGRESSES EASTWARD AND TO ND BY THIS EVENING...BUT ONLY
SLIGHTLY DEEPENING DUE TO THE PARENT UPPER WAVE DE-AMPLIFYING.
BETWEEN THE EASTERN HIGH AND THE NORTHERN PLAINS LOW THE LOW LEVEL
FLOW WILL GRADUALLY VEER FROM SOUTHEASTERLY TO SOUTH-SOUTHWESTERLY
WHILE BECOMING SOMEWHAT GUSTY BY MIDDAY AS THE MIXED LAYER DEEPENS
ENOUGH TO TAP INTO THE INCREASING SOUTHWEST FLOW BETWEEN 1000 AND
2000 FT AGL PROGGED AT AN AVERAGE OF AROUND 22KT BY 10.00Z.
ANALYSIS OF 09.00Z RAOB DATA SHOWED SIGNIFICANT 700 HPA WARM AIR
ADVECTION REACHING ACROSS SOUTHERN WI AND NORTHERN IL...WITH THE
850 HPA ANALYSIS SHOWING STRONG WARM AIR ADVECTION ACROSS IA AND
NORTHERN MO. EXAMINATION OF LOWER AND MID LEVEL ISENTROPIC SURFACE
HEIGHTS...PRESSURE ADVECTION...AND SATURATION DEFICIT 6 HOUR PROGS
OF THE 09.00Z NAM80 VERIFIED QUITE WELL BASED ON SATELLITE
PICTURES AND METARS AS TO WHERE STRATOCUMULUS AND ALTO-CUMULUS
WOULD BE LOCATED. BASED ON THE VERY GOOD SHORT TERM PERFORMANCE
HAVE USED THE ABOVE MENTIONED PARAMETERS OF THE 00Z NAM80 MODEL
RUN TO PROJECT WHERE LOWER AND MID LEVEL CLOUDS WILL BE LOCATED
LATER TODAY.
RECENT SATELLITE PICTURES AND METARS PUT THE SOUTHWESTERN EDGE OF
THE STRATOCU ROM FAR SOUTHWEST WI ACROSS FAR NORTH CENTRAL AND
FAR NORTHEAST IL TO NORTHWEST IN...WITH THE BACK EDGE OF THE MID
LEVEL CLOUD DECK FURTHER TO THE NORTHWEST THROUGH NORTH-NORTHEAST
OF THE LOCAL AREA. THE NOSE OF THE MID AND LOWER LEVEL WARM AIR
ADVECTION IS PROGGED TO CONTINUE TO PUSH TO THE EAST-NORTHEAST
INTO THE GREAT LAKES WITH TIME TODAY AND EXPECT THE BACK EDGE OF
THE STRATOCU DECK TO DO THE SAME AND FOR THE MOST PART CLEAR OF
THE TERMINALS BY MID MORNING.
THE VEERING LOW LEVEL FLOW HAS BEEN SLOWLY ADVECTING IN SLIGHTLY
HIGHER DEW POINTS DURING THE LATE NIGHT SO EXPECT SOME VERY LIGHT
FOG AND/OR HAZE DURING THE PREDAWN THROUGH EARLY MORNING HOURS.
DEW POINTS LOCALLY ARE PROGGED TO CONTINUE TO SLOWLY CLIMB INTO
THE UPPER 60S AND LOWER 70S BY MIDDAY AS THE LOW LEVEL FLOW
CONTINUES TO VEER FROM SOUTHEASTERLY O OUT OF THE SOUTH. GENERALLY
CLEAR SKY DURING THE MID AND LATE MORNING WILL ALLOW GOOD SURFACE
HEATING WARMING THE SURFACE TO PROGGED CONVECTIVE TEMPERATURES IN
THE MID 80S BY EARLY AFTERNOON SO EXPECT SCATTERED CUMULUS
DEVELOPMENT BUT COVERAGE WILL BE LIMITED AS ADDITIONAL HEATING AND
DEEPENING OF THE MIXED LAYER DROPS DEW POINTS A BIT AS THE
AFTERNOON PROGRESSES.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE THAT VISIBILITIES PRE-DAWN AND EARLY A.M. WILL
REMAIN VFR...HIGH CONFIDENCE NO LOWER THAN HIGH END MVFR.
* MEDIUM CONFIDENCE IN FORECAST AVERAGE VELOCITY OF GUSTS LATER
MORNING THROUGH AFTERNOON +/- 3KT.
* HIGH CONFIDENCE ALL OTHER FORECAST TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...VFR. CHANCE OF TSRA WITH MVFR POSSIBLE TUES NGT.
WEDNESDAY...CHANCE TSRA. MVFR POSSIBLE.
THURSDAY THROUGH SATURDAY...VFR.
RATZER
&&
.MARINE...
139 PM CDT
THE WINDS ACROSS THE LAKE HAVE VEERED EASTWARD IN RESPONSE TO THE
SURFACE HIGH BUILDING EASTWARD ACROSS FAR SOUTHERN ONTARIO AND THE
UPPER GREAT LAKES. THIS SURFACE HIGH WILL CONTINUE
EAST-SOUTHEASTWARD ACROSS THE NORTHERN ATLANTIC COAST BY EARLY
MONDAY. THIS WILL ALLOW THE WINDS TO CONTINUE VEERING TO THE
SOUTHEAST TONIGHT...AND THEN SOUTHERLY FOR MONDAY. WIND SPEEDS WILL
LIKELY REMAIN ELEVATED UP TO 15 TO 25 KT INTO MONDAY. HOWEVER...IT
APPEARS THAT SOME 30 KT SOUTHERLY WINDS WILL DEVELOP LATE MONDAY
AND MONDAY NIGHT...ESPECIALLY OVER THE NORTHERN HALF OF THE LAKE AS
A POTENT AREA OF LOW PRESSURE TRACKS ACROSS LAKE SUPERIOR.
THIS LOW LOOKS TO DROP A WEAK COLD FRONT ACROSS THE LAKE BY TUESDAY
NIGHT. HOWEVER...THE WIND SPEEDS LOOK TO ABATE DURING THIS TIME. A
SECOND AREA OF LOW PRESSURE IS FORECAST TO SHIFT ACROSS ONTARIO
AROUND MID WEEK...AND THIS LOW LOOKS TO DROP A MUCH STRONGER COLD
FRONT DOWN THE LAKE INTO THURSDAY. A PERIOD OF STRONG NORTHERLY
WINDS IS POSSIBLE BEHIND THIS FRONT LATER IN THE WEEK AS A MUCH
COLDER AIR MASS SPILLS OVER THE LAKE AHEAD OF A POTENT SURFACE HIGH.
FOR THE NEAR SHORE WATERS...I PLAN ON KEEPING THE SMALL CRAFT
ADVISORY AS IS THROUGH THIS EVENING FOR 4 TO 7 FOOT WAVES ALONG THE
ILLINOIS NEAR SHORES. THE WAVES WILL LIKELY BE SLOW TO SUBSIDE
TONIGHT ALONG THE NORTHERN ILLINOIS NEAR SHORES...BUT IT APPEARS
THAT THEY WILL SUBSIDE INTO THE 2 TO 5 FOOT RANGE...THUS AN
EXTENSION TO THE SMALL CRAFT ADVISORY IS NOT ANTICIPATED AT THIS
TIME.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
Area Forecast Discussion
National Weather Service Lincoln IL
1105 PM CDT Sun Sep 8 2013
.DISCUSSION...
ISSUED 842 PM CDT Sun Sep 8 2013
Latest surface analysis indicates the "cool" front that pushed
through our area early this morning has started back north as a
warm front this evening. Most winds, except for our far north and
east, have turned more into a southeast to south direction
suggesting the boundary is lifting thru our forecast area. Question
now is precip chances with the boundary already shifting into our
northern areas this evening. 00z 850 mb map indicates the warm front
situated from from eastern Iowa thru extreme west central IL. Some
weak speed convergence noted over northeast Mo and west central IL
early this evening but the stronger core of winds was well to our
west. Last several runs of the HRRR model showing some showers trying
to develop over extreme southwest IL after midnight and then tracking
south. Evening 700 mb map indicating another surge of very warm
air...+12C just to our west, which should advect into our area on
Monday as upper level heights build over the region with some very
hot temperatures for the first half of the work week.
Overall, zone forecast is in good shape. Only making some minor
adjustments to the overnight hours, specifically for temperatures
and cloud cover, along with some overnight adjustments to wording
in the ZFP. Should have the update out by 900 pm.
&&
.AVIATION...
ISSUED 1105 PM CDT Sun Sep 8 2013
Other than the threat for some MVFR vsbys in fog from 09z-13z, we
are still expecting VFR conditions for the remainder of the period.
Warm frontal boundary edging slowly north across the forecast area
tonight and will be north of our area by Monday morning. Abudant
low level moisture and lack of cloud cover, along with a light wind
regime should lead to at least some patchy fog just before dawn. What
fog we do see during the early morning hours should quickly dissipate
by 14z as south to southwest winds increase to 10 to 15 kts with a
few gusts possible during the afternoon, and then diminish to around
10 kts by 00z. Forecast soundings indicate some cumulus clouds will
form by early afternoon, mainly east of I-55, affecting DEC and CMI
with cloud bases of 4500-5000 feet, which should dissipate by 23z.
Smith
&&
.PREV DISCUSSION...
ISSUED 250 PM CDT Sun Sep 8 2013
SHORT TERM...Today through Thursday
A frontal boundary over central IN/IL to near the IA/MO border
will linger isolated showers and thunderstorms into this evening.
MCS that brought heavy rains to westcentral IL overnight/early
this morning has dissipate as it moved sse into southern IL by
afternoon. Not much lift or convergence along frontal boundary but
heating of tropical airmass with dewpoints in the upper 60s to
near 70F giving unstable capes peaking from 1.5-3K j/kg late this
afternoon. Some stratus and fog more likely over northern IL
tonight as front lifts northward toward northern IL overnight.
Areas from I-74 north may see some of this stratus and fog but
more likely further north. Lows overnight close to dewpoints in
the upper 60s, to near 70F sw areas.
Hot conditions still on tap for Monday and Tuesday with highs in
the low to mid 90s Monday and into the 90s Tuesday with some upper
90s sw areas. Will likely be shy of record highs near 100F on
Monday but may be close to record highs on Tuesday which are 97F
at Peoria and Lincoln and 98F in Springfield. Kept dry conditions
from Monday through Tuesday as 592 dm 500 mb subtropical ridge
over the central plains shifts ese into the mid ms and tn valleys.
Models continue to drive a cold front se toward nw IL late
Wednesday and brings a chance of showers and thunderstorms mainly
to the IL river valley. Cold front to push se through central and
se IL Wed night and bring a chance of showers and thunderstorms
with isolated convection lingering over se IL thursday. Still
quite warm and humid Wed with highs in the lower 90s, with some
upper 80s nw of the IL river where more clouds arrive during the
day Wed. Highs Thu mostly in the mid 80s.
LONG TERM...Thursday night through Sunday
A quiet and cooler/less humid pattern expected during this time
with highs in the mid to upper 70s Fri into this weekend and lows
in the low to mid 50s. Large Canadian high pressure of 1027 mb
settles se into the Great Lakes region by Saturday morning and to
control IL`s weather for a few days. GFS and ECMWF models show a
disturbance moving ne toward central IL later in the weekend but
will keep a dry forecast since models first time showing this.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1148 PM CDT Sun Sep 8 2013
.SHORT TERM...(This Evening through Monday)
Issued at 305 PM CDT SUN SEP 8 2013
At 2 PM, a weak surface trough was oriented from east to west across
northern Kansas on Sunday afternoon, co-located with the axis of
warmest 850 temperatures. A very weak front/outflow boundary with
minimal convergence in the low levels was stationary within 30 miles
of the Nebraska border as well, with a cluster of showers and
thunderstorms in extreme northeast Kansas and northwest Missouri.
Temperatures just to the south of the weak surface boundary have
become extremely warm, ranging from 99 to 104 degrees early this
afternoon, and while some drier air has mixed to the surface,
dewpoints remain in the lower to middle 60s. These conditions along
with the expectation for further heating through 4 PM have prompted
issuance of a heat advisory for heat index values in the 104 to 107
range.
Aside from the heat, potential for more vigorous thunderstorm
development is the other forecast focus today. The most recent runs
of the HRRR and NMM models continue to suggest thunderstorm
development on the warm side of the weak surface front by middle to
late afternoon, potentially linked to any outflow moving southwest
out of ongoing convection in NW Missouri. These storms are not
expected to be particularly organized or strong owing to only weak
to moderate CAPE and very weak vertical shear. However, it would
seem to be a rather favorable setup for microbursts given the dry
adiabatic to superadiabatic lapse rates from the surface to 700 hpa
and favorable downdraft CAPE. The primary uncertainty lies in
whether storms will actually develop over the deeply mixed airmass
as parcels would need to be lifted through a very deep mixed layer
before freely convecting. The best chance for storms would seem to
be northeast of a line from Belleville to Junction City to Ottawa.
Any storms should come to an end by 10 PM. Temperatures will fall
off nicely but a south breeze is expected to persist through the
night and will probably keep low temps in the low to mid 70s. Monday
will be quite hot once again, but with the upper ridge progressing
east of the area, 850 temps are forecast to drop by 2 to 3 degrees
from Sunday and highs may hold in the middle to upper 90s. Southwest
winds will be quite a bit stronger than Sunday with an increasing
pressure gradient. The southwest flow should also support greater
dry air advection into the forecast area which will probably support
very high fire danger with any dry vegetation.
Barjenbruch
.LONG TERM...(Monday Night through Sunday)
Issued at 305 PM CDT SUN SEP 8 2013
Monday night upper level trough progresses eastward through the
northern plains. As this system pushes into the Great Lakes region a
cold front will move southward into the region. Temperatures at 850
will cool significantly over the central plains as the shortwave
continues eastward and the upper high shifts into the OH river
valley. High temperatures reach the mid 90s area wide on Tuesday.
The front will approach the cwa on Tuesday evening and there is a
slight chance for showers and thunderstorms along the front mainly
across southern NE with an outside chance of reaching the northern
counties. Overnight Tuesday the front sags south into the cwa
increasing the chances for storms north of interstate 70s as the
progress of the front slows down. Due to cloud cover associated with
the possible precip high temperatures on Wednesday could remain in
the upper 80s to low 90s.
The front continues to slowly push south across the cwa therefore
have maintains pops through Friday. Convergence along the front and
upper level forcing appears to be rather weak, but cooler mid level
temps will allow for a weaker cap in place. Front exits the area
sometime on Thursday night or Friday as a shortwave digs southeast
through the eastern longwave trough. A surface high pressure will
build northeast of the region and likely control how far the front
is pushed southward. Once the front passes return flow isentropic
lift may generate precip mainly across central and western KS
possible spreading into our western counties. Next weekend another
front will possibly move into the central plains. Temperatures look
to gradually cool behind the front with high temperatures in the
upper 70s to low 80s by Friday, and low temperatures generally in
the upper 50s to low 60s.
&&
.AVIATION...(For the 06Z TAFs through 06Z Monday Night)
Issued at 1145 PM CDT SUN SEP 8 2013
Vfr conditions will prevail at all terminals through the fcst period.
Sustained south to southwest winds under 10 kts through 13z will
increase into the 13-15kt range by 15z with gusts over 20 kts thru
the remainder of the fcst period...although some decrease in
sustained speeds and gusts should occur aft 00Z/10.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Barjenbruch
LONG TERM...Sanders
AVIATION...63
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
536 AM EDT MON SEP 9 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 536 AM EDT MON SEP 9 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MID LEVEL LOW OVER MT.
LOW IS WEAKENING/OPENING UP AND FINALLY MOVING E AFTER BEING OVER
THE PACIFIC NW DURING THE LAST FEW DAYS. AHEAD OF THIS FEATURE...
SHRA/TSRA OVER THE WRN DAKOTAS LAST EVENING HAVE ORGANIZED INTO A
WELL DEVELOPED MCS WHICH IS NOW MOVING ACROSS THE ERN DAKOTAS. PER
LATEST RUC/SPC MESOANALYSIS...40-50KT LOW-LEVEL JET IS ADVECTING
MUCAPE OF 3000J/KG INTO THE COMPLEX...HELPING TO MAINTAIN IT. MCS IS
MOVING AROUND A WEAKENING RIDGE WHICH REMAINS OVER THE CNTRL CONUS.
CLOSER TO HOME...SOME -SHRA...MOSTLY JUST SPRINKLES...HAVE PUSHED
ACROSS THE WRN AND SRN FCST AREA OVERNIGHT IN A GENERALLY WEAK
ISENTROPIC ASCENT REGIME. OVER THE LAST COUPLE OF HRS...SOUTHERLY
FLOW UP LAKE MICHIGAN HAS INCREASED ENOUGH TO BEGIN PUSHING HIGHER
DWPT MARINE LAYER AIR INTO THE ERN FCST AREA. WITH TEMPS IN THE
INTERIOR IN THE 40S/LWR 50S...MAY SEE SOME FOG/STRATUS DEVELOP THERE
IN THE NEXT COUPLE OF HRS.
INITIALLY...WILL CARRY ISOLD/SCT SHRA ACROSS THE FCST AREA FOR THE
NEXT SEVERAL HRS IN ONGOING MODEST WAA/ISENTROPIC ASCENT. THEN...
SHORT TERM FCST WILL REVOLVE AROUND PROGRESS OF THE SYSTEM OVER MT
AND MORE IMPORTANTLY THE MCS OVER THE DAKOTAS. AS ALWAYS...PINNING
DOWN CONVECTION EVEN IN THE SHORT TERM IS A CHALLENGE. TODAYS FCST
IS ESPECIALLY CHALLENGING GIVEN THE WELL-DEVELOPED MCS NOW OVER THE
ERN DAKOTAS AS IT SEEMS QUITE LIKELY THAT AN MCV WILL SPIN UP AND
MAY BECOME THE MAIN FEATURE TO KEY ON FOR THE PCPN FCST HERE. TRIED
TO INCORPORATE THE IDEA OF THE MCS HOLDING TOGETHER TO SOME EXTENT.
AS IT LIFTS ENE...MAY SEE AN ARC OF SHRA/TSRA SWING ACROSS
ESPECIALLY NW UPPER MI LATER THIS MORNING IN ZONE OF ENHANCED
WAA/ISENTROPIC ASCENT. WHAT TRANSPIRES AFTERWARDS IS UNCERTAIN. IF
MCV TRACKS N OF THE AREA...THE MAIN CLUSTER OF SHRA/TSRA WILL PASS
MOSTLY N OF UPPER MI TODAY WITH TAIL OF WAVE POSSIBLY GENERATING A
BAND OF SVR STORMS LATE AFTN/EVENING AS MLCAPE UPWARDS OF 2000J/KG
BUILDS NE INTO UPPER MI IN THE PRESENCE OF 40-50KT DEEP LAYER SHEAR.
IF MCV PASSES ACROSS UPPER MI...THEN MOST AREAS WILL SEE A FEW HRS
OF SHRA/TSRA THIS AFTN...AND MAIN SVR THREAT COULD BE SHUNTED S FOR
THE LATE AFTN/EVENING. BASED ON RADAR TRENDS...IT APPEARS THE FORMER
IDEA MAY BE THE MORE LIKELY SCENARIO. DEPENDING ON HOW FAR N WARM
SECTOR CAPPED AIR MASS ADVECTS TODAY...SRN FCST AREA MAY SEE
LITTLE/NO CONVECTION AFTER INITIAL POSSIBLE SHRA/TSRA IN
AFORMENTIONED ZONE OF ENHANCED WAA/ISENTROPIC ASCENT PASSES LATER
THIS MORNING.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 412 AM EDT MON SEP 9 2013
TUESDAY MORNING WILL MARK THE BEGINNING OF A COOLER AND GENERALLY
DRIER TREND THAT WILL REMAIN THROUGH THE REST OF THE FCST PERIOD.
850MB TEMPS AT DAYBREAK TUESDAY SHOULD BE 14-19C...WHICH WILL NOT BE
SEEN AGAIN UNTIL NEXT TUESDAY AT THE EARLIEST.
THE SFC LOW WILL BE EXITING/SLOWLY SINKING TO OUR SE ON TUESDAY...AS
A RIDGE BRIEFLY SLIDES IN. WHILE THERE WILL BE A PERIOD OF DRY
WEATHER...IT WILL BE SHORT LIVED...AS A SERIES OF SHORTWAVES WILL
KEEP IMPACTING THE UPPER GREAT LAKES THROUGH THE DAY THURSDAY.
HIGH PRESSURE WILL BUILD IN AT THE SFC AND ALOFT THURSDAY NIGHT. THE
COLDEST AIR WILL LIKELY BE OVERHEAD THURSDAY NIGHT INTO FRIDAY
MORNING...WITH BOTH THE GFS AND ECMWF INDICATING 850MB TEMPS BETWEEN
0 AND -2C FROM 00Z-12Z FRIDAY ON NNW-NE WINDS OFF LAKE SUPERIOR.
WHILE THERE WILL BE SOME DRYING THURSDAY NIGHT WITH HIGH PRESSURE
ROLLING IN...DIMINISHING 15-20KTS WINDS OFF LAKE SUPERIOR WILL HELP
KEEP LOW LEVEL MOISTURE STUCK ACROSS N UPPER MI INTO FRIDAY MORNING
AS A STRENGTHENING INVERSION TAKES HOLD. FRIDAY MORNING TEMPERATURES
ARE TRICKY. THE 09/00Z RUN OF THE GFS WARMED 850MB TEMPS 2C ON
AVERAGE...WHICH IS APPROX 3-4C WARMER THAN THE 09/12Z ECMWF.
AS THE SFC HIGH EXITS FRIDAY AFTERNOON/EVENING...SLIGHTLY WARMER AIR
WILL BE ABLE TO SWING IN ON W-SW WINDS. THERE WILL STILL BE THE
POTENTIAL FOR PATCHY FROST...BUT MOST LIKELY OVER THE INLAND E
LOCATIONS THAT ARE STILL UNDER THE LINGER INFLUENCE OF THE EXITING
HIGH. WHILE 80 DEGREE TEMPS WILL NOT RETURN...50 DEGREE READING ON
FRIDAY WILL RISE INTO THE MID 60S FOR THE UPCOMING WEEKEND. THE
WARMER TEMPERATURES WILL BE ACCOMPANIED BY A CHANCE OF SHOWERS TO
WRAP UP THE WEEKEND. WILL KEEP THE MENTION OF TS OUT FOR SUNDAY...AS
THE BEST POTENTIAL SHOULD REMAIN WELL TO OUR SW...CLOSER TO THE SFC
LOW ACROSS THE CENTRAL PLAINS WHERE MUCH WARMER AIR WILL RESIDE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 121 AM EDT MON SEP 9 2013
WITH INCREASING SOUTHERLY WINDS OVERNIGHT INTO THE MORNING...EXPECT
LOW LEVEL MOISTURE OVER WISCONSIN TO BE DRAWN INTO UPPER MICHIGAN
AND MVFR CIGS TO DEVELOP AT CMX/SAW. EVEN WITH DOWNSLOPING FLOW INTO
IWD...MVFR AND POSSIBLY IFR CIGS ARE ALSO EXPECTED.
WHILE SOME LIGHT SHOWERS OR SPRINKLES ARE POSSIBLE OVERNIGHT...
THE BEST OPPORTUNITY FOR SHOWERS IS EXPECTED FROM LATE MORNING INTO
THE EARLY AFTERNOON AS A WARM FRONT LIFTS THROUGH THE AREA TODAY.
CONFIDENCE ON TIMING/LOCATION IS ONLY MODERATE BUT PCPN SHOULD BE
WIDEPSREAD ENOUGH TO MENTION SHRA. POTENTIAL FOR TSRA IS LESS CERTAIN
AND WAS NOT INCLUDED AT THIS TIME.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 AM EDT MON SEP 9 2013
LOW PRESSURE OVER SD WILL PUSH THE EXITING RIDGE ACROSS LAKE
SUPERIOR EASTWARD TODAY. FUNNELING NE WINDS WILL GUST TO 20-25KTS
OVER FAR W LAKE SUPERIOR THIS AFTERNOON AND EVENING. EXPECT THE LOW
TO CROSS S LAKE SUPERIOR OVERNIGHT...AND PUSH INTO FAR SE ONTARIO ON
TUESDAY. A BRIEF RIDGE WILL MOVE OVER LAKE SUPERIOR TUESDAY
AFTERNOON THROUGH TUESDAY NIGHT...OUT AHEAD OF A WEAK TROUGH
EXTENDING FROM NORTHERN ONTARIO DURING THE DAY WEDNESDAY. LARGE HIGH
PRESSURE OVER SOUTH CENTRAL CANADA WEDNESDAY NIGHT WILL SLOWLY SINK
ACROSS GREAT LAKES...WHERE IT WILL REMAIN FROM THURSDAY NIGHT
THROUGH FRIDAY NIGHT. NW WINDS WILL LIKELY GUST 20-30KTS LATE
WEDNESDAY NIGHT THROUGH LATE THURSDAY NIGHT AS HIGH PRESSURE SINKS
IN FROM THE NNW. OTHERWISE WITH HIGH PRESSURE OVERHEAD...LIGHT WINDS
LESS THAN 20KTS ARE EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...JLB
MARINE...KF
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
400 AM CDT Mon Sep 9 2013
.SHORT TERM...(Today through Tuesday)
Issued at 352 AM CDT MON SEP 9 2013
The unseasonably hot conditions will continue today with near record
heat in parts of northern and west central MO. While H8 and 925mb
temperatures are progged to be 1-2C lower than Sunday when triple
digit readings were reached in the KC Metro, mixing will be better
and deeper due to increasing southwest winds. The net effect will be
afternoon temperatures topping out in the middle to upper 90s. If
there is any silver lining to today`s heat it`s the expectation of
lower humidity levels due to this better mixing.
The large anticyclone aloft will be nearly overhead and with its hot
mid level temperatures will suppress most cloud clover let alone any
convective development. However, there is one caveat to this
scenario and it revolves around a weak surface trough extending from
near OMA southeast through central MO. Some of the very short range
models like the RAP and HRRR are hinting at some elevated convection
near this boundary +/- 2-3 hours centered around 12Z. While the
models have been overly generous with qpf the last couple days with
the boundaries that have migrated into the CWA the latest satellite
imagery shows patches of apparently mid clouds forming from far east
central KS to central MO. Will need to monitor radar/satellite for
any development as the current forecast is dry.
Tuesday: more of the same although temperatures look like they will
be a few degrees cooler as the pool of hot air shifts northward.
Nonetheless, temperatures will remain a good 10F above average.
Lacking any boundary and with nearly non-existent moisture under a
strong cap will go with zero PoPs.
Tuesday night: A cold front from southern NE through WI will sag
slowly southward and possibly reach far northwest MO by Wednesday
morning. Models are becoming more reluctant to generate qpf over the
CWA as any convection which forms during this period will likely be
post-frontal. Have confined PoPs to far northwest MO and left rest
of CWA dry.
.LONG TERM...(Wednesday through Sunday)
Issued at 352 AM CDT MON SEP 9 2013
A rather weak front is expected to sink into northern Missouri by
Wednesday morning, but with limited precipitation accompanying it.
A narrow corridor of low level moisture will stretch across southern
Nebraska eastward into central Illinois into Thursday. Depending on
cloud cover, temperatures may again climb into the lower or even
middle 90s Wednesday afternoon and while low, a few thunderstorms
may develop in the unstable airmass south of the boundary.
Slightly higher PoPs are focused Wednesday night into Thursday as
the low-level baroclinic zone shifts southward. However, the LLJ
will back through the night into NW Kansas and SW Nebraska likely
forcing higher precipitation chances well west of the local area.
A secondary cold front will sweep into the area Thursday night,
allowing cool and dry air to push southwest. Temperatures heading
into the weekend will find themselves near the seasonal normals in
the upper 70s to lower 80s. An upper low crossing the Rockies over
the weekend will allow winds to turn back southwesterly on Saturday,
before another front moves into the area Sunday/Monday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1152 PM CDT SUN SEP 8 2013
VFR conditions are expected through the period. Primarily a wind
forecast, with south-southwesterly wind speeds increasing by late
morning and decreasing around sunset.
&&
.FIRE WEATHER...
Issued at 352 AM CDT MON SEP 9 2013
There is an elevated fire danger threat this afternoon across
northern and west central MO as well as extreme east central KS. The
heat of the past several days has quickly dried out the native
grasses. This combined with drought conditions across the area plus
humidity levels between 25 and 30 percent and southwest winds gusting
to 20 to 25 mph will increase the risk of rapid fire growth which
could quickly burn out of control.
&&
.CLIMATE...
Issued at 352 AM CDT MON SEP 9 2013
Record or near record heat is expected Monday afternoon over parts of
northern and west central MO and extreme east central KS.
Sep 9 record high/year
St. Joseph 98/1955
Kansas City 99/1970
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...MJ
LONG TERM...Dux
AVIATION...Blair
FIRE WEATHER...MJ
CLIMATE...MJ
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1155 PM CDT Sun Sep 8 2013
.UPDATE:
Issued at 856 PM CDT Sun Sep 8 2013
Scattered showers that were over the eastern Ozark counties
earlier this evening rotated south around the upper high that is
currently centered over northwest Missouri. The RAP/HRRR still
indicates the potential for the redevelopment of thunderstorms
along and east of the Mississippi river between 06-12Z tonight, so
have concentrated slight chances of rain the rest of the night in
these locations. This is where the HRRR develops N-S band of
storms in an area of 925-850mb moisture convergence seen on the
RAP. Some fog will also be possible tonight where skies clear
with light winds, particularly where heavy rain fell earlier
today.
Britt
&&
.SHORT TERM: (Through Late Tonight)
Issued at 335 PM CDT Sun Sep 8 2013
The primary forecast issue for tonight is precipitation chances.
Unfortunately, this is not a straightforward forecast. The cold
front which was supposed to have moved through the CWA last night
has instead stalled near the MO/IA border, and the MCS which moved
through the CWA earlier today has also changed the situation with
respect to precipitation chances for tonight.
First, the aforementioned MCS produced several hours of steady
rainfall across most of the CWA, significantly moistening the lower
levels of the atmosphere. Second, differential heating between the
clear skies over western MO and the MCS-generated clouds over
eastern MO has produced a surface boundary that resembles a warm
front, including surface convergence noted on afternoon METARs. This
feature stretched from NW MO to near KCOU and then southward into
the Ozarks, and it is distinct from the true synoptic warm front
which was located from the Dakotas through IA and MN and then into
northern IL. Third, a persistent cluster of showers and
thunderstorms has already developed over extreme northwestern MO.
Model forecasts suggest that the H85 LLJ will interact with the
synoptic warm front well to our north tonight, and this scenario
still looks very reasonable. However, our concern is whether
additional thunderstorms will develop farther south, mainly across
parts of MO. H85 winds to the southeast of the main LLJ core are
forecast to veer with time and would impinge on the convergence zone
(remnant of the differential heating boundary), if it still exists,
and the overnight MUCAPE axis is forecast to extend into the LSX
CWA. Admittedly, there are a lot of "ifs" and "mights" when it comes
to thunderstorm chances tonight, but there`s enough substance here
to warrant slight chance PoPs until the atmosphere shows its hand
over the next several hours.
Kanofsky
.LONG TERM: (Monday through Next Sunday)
Issued at 335 PM CDT Sun Sep 8 2013
12z guidance continues to support the thinking that hot September
weather will dominate the region on Monday and Tuesday as the upper
ridge shifts east into the Ohio valley. This mornings UA data
indicated 850 mb temps aoa 24C over a large section of the central
plains, and this air should advect into the mid-Mississippi valley
with time. Some residual cloudiness may hinder the warm up just a
bit over our far se counties, but with this thermal ridge punching
across the n half of our CWA temps should easily be in the mid-upper
90s both Monday and Tuesday. It`s not out of the question that some
areas will approach the century mark due to deep mixing in this hot
airmass with a pronounced westerly component to the low level flow
and strong sunshine. And, (in spite of todays rain) dry soil and
vegetation remains in many areas, and especially in those locations
north of highway 36 where little if any rain fell today.
Aforementioned mixing should allow a fairly substantial drop in
dewpoints during the afternoon hours, especially in the hottest air
over n sections of the CWA. Calculated hourly apparent temperatures
based on this thinking is still capping the HI at around 100 in some
spots, so no heat headlines needed at this time.
As far as rain potential is concerned, if storms do form
overnight believe that most of them will be drifting out of the
area by morning. Based on development and timing its possible
later shifts may have to hang onto some pops for early Monday
morning, but due to considerable uncertainty on location, timing,
and even occurrence of overnight convection have maintained a
rain-free forecast for Monday morning. Another nagging concern is
the spotty rainfall that the NAM, GFS, and even the ECMWF have
been trying to generate over our southeast counties over the past
few days. 12z runs are also hinting at this, but are a bit more
sporadic with this than earlier solutions. The only mechanism I
can see for this is ams-type diurnal convection, perhaps aided by
a bit of orographic lift into the eastern Ozarks. However,
directly beneath an upper ridge seems like an odd place for this
to occur (current activity going up near STJ notwithstanding). At
this point will maintain dry forecast, and let mid shift take
another look at short range guidance to determine if the inclusion
of POPs is warranted.
Latest medium range guidance also hasn`t changed much in their
handling of cold front and its southward push across the mid-
Mississippi valley in the Wednesday night-Thursday time frame as
upper trof begins to develop over the eastern CONUS. Have kept
POPs in the chance category for now due to rather weak dynamics
and what appears to be limited convergence along the front.
Since fropa won`t occur in our area until Wednesday night have
kept Wednesdays temps aoa guidance in all but northern sections
of the CWA where some afternoon clouds and convection will be
possible. Going temp trends for remainder of the extended (which
reflect continued cooling into Saturday) still look reasonable as
large Canadian high builds into the eastern U.S.
Truett
&&
.AVIATION: (For the 06z TAFs through 06z Monday Night)
Issued at 1142 PM CDT Sun Sep 8 2013
Primary concern for the rest of the night remains the probability
of isolated-widely scattered showers and thunderstorms
redeveloping along and east of the Mississippi River. It looks
like the best chance has shifted mostly to south of the St. Louis
Metro area across parts of the eastern Ozarks and southwest
Illinois. It does not look like a particularly strong or organized
round of showers and storms, but the signals in the models aren`t
very strong so confidence is low. VFR flight conditions should
prevail outside of any precipitation, except in area river valleys
where intermittent MFR conditions in fog can be expected.
VFR flight conditions are expected to prevail on Monday. The wind
will be increasing from the southwest with potential for gusts to
around 20kits especially across parts of central and northern
Missouri as well as west central Illinois.
Specifics for KS TL:
Expect VFR flight conditions to prevail for the rest of the night
at Lambert. Isolated showers are still possible...but the best
chances for rain look to have moved south/southeast of the
terminal. Signals in the models for rain aren`t particularly well
defined, so confidence in timing and locations of the showers is
low. River valley fog can be expected west of the terminal, but
shouldn`t impact the runway complex.
VFR flight conditions are expected to continue to prevail on
Monday. The wind will be increasing from the southwest in the
morning...and this will likely cause a brief period of direct
crosswinds on the main runways. However, the wind should continue
veering past 210 degrees by mid-late morning.
Carney
&&
.CLIMATE:
ISSUED AT 306 PM CDT SAT SEP 7 2013
RECORD HIGHS:
SEPT 9 SEPT 10
STL 101/1925 98/1983
COU 99/1925 99/1938
UIN 100/1945 100/1933
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
348 AM EDT MON SEP 9 2013
.SYNOPSIS...
AN AREA OF HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES
WILL MOVE OFF THE NEW ENGLAND COAST TODAY. THIS WILL ALLOW A WARM
FRONT TO LIFT NORTHEAST ACROSS THE LOCAL AREA. AN AREA OF LOW
PRESSURE WILL PASS WELL TO THE NORTH ON WEDNESDAY AND DRAG A COLD
FRONT ACROSS THE REGION ON WEDNESDAY NIGHT. HIGH PRESSURE WILL
RETURN FOR THE END OF THE WORKWEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
QUITE A BIT OF SHOWER AND THUNDERSTORM ACTIVITY OVER SW LOWER
MICHIGAN. THIS ACTIVITY HAS FORMED ALONG A WARM FRONT THAT WILL
LIFT NE ACROSS THE LOCAL AREA TODAY. ALL OF THE NEW
GUIDANCE...INCLUDING THE HRRR AND CONVECTIVE SREF SHOW AT LEAST
SCATTERED PRECIP. HAVE BUMPED PRECIP CHANCES UP ALL AREAS TO
AROUND 40 PERCENT. MAY EVENTUALLY HAVE TO BUMP IT EVER FURTHER
DEPENDING ON WHAT THE ACTIVITY OVER MI DOES. DEWPOINTS ARE ALREADY ON
THE WAY UP AND EXPECTING MID 60S BY EARLY EVENING. THERE SHOULD
BE A LOT OF CLOUDINESS TODAY BUT TEMPS WILL STILL MAKE THE 80S
OVER ALL BUT THE EASTERN END OF THE AREA.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
THE WARM FRONT WILL MOVE NORTH OF LAKE ERIE THIS EVENING AND THAT
SHOULD END THE THREAT FOR ADDITIONAL PRECIP. WILL START THE
TONIGHT PERIOD OUT WITH SMALL POPS...ESPECIALLY ACROSS NW PA. THE
REMAINDER OF THE NIGHT AND TUESDAY SHOULD BE DRY. MODELS STILL
PUSHING 850 MB TEMPS TO PLUS 20 OR WARMER ON TUESDAY. NEW GUIDANCE
IS A TAD COOLER WITH HIGHS BUT HAVE NOT MADE ANY SIGNIFICANT
CHANGES. MUCH OF THE AREA SHOULD REACH THE 90 DEGREE MARK. THE
WARM AND HUMID AIRMASS WILL REMAIN IN PLACE ON WEDNESDAY AS WELL.
THERE SHOULD BE MORE CLOUDS AND INCREASING CHANCES FOR PRECIP.
THIS WILL HOLD TEMPS BACK A LITTLE. IT APPEARS THAT THE BEST
CHANCES FOR CONVECTION DURING THE PERIOD WILL COME WEDNESDAY
EVENING AND NIGHT AS THE COLD FRONT FINALLY ARRIVES. HAVE GIVEN
MUCH OF THE AREA LIKELY POPS. THERE WILL BE A DISTINCT AIRMASS
CHANGE BEHIND THE FRONT. STRONG COLD AIR ADVECTION IS EXPECTED
BEHIND THE FRONT ON THURSDAY. THE MODELS TRY TO DRY THINGS OUT
QUICKLY BUT SUSPECT THAT THIS IS TOO FAST. WILL LIKELY SEE A FAIR
AMOUNT OF CLOUDINESS AND PERHAPS A FEW SHOWERS DOWN WIND OF THE
LAKE. AFTER TUESDAY HAVE USED A BLEND OF GUIDANCE TEMPS.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
TROUGH ALOFT FRIDAY WITH A VERY COOL AIRMASS. STILL GOOD CONSENSUS
THAT H8 TEMPS WILL BE BETWEEN +2C AND +5C. WILL KEEP THE HIGHS IN
THE 60S BOTH FRIDAY AND SATURDAY...WITH EVEN SOME UPPER 50S ACROSS
NW PA ON FRIDAY. FAIRLY CLOUDY TO START FRIDAY WITH ADDITIONAL LAKE
CLOUDS...BUT BY LATE AFTERNOON HIGH PRESSURE FROM THE CENTRAL LAKES
REALLY BEGINS TO BUILD IN. WILL ALSO KEEP SOME LOW PRECIP CHANCES
FOR LAKE EFFECT RAIN SHOWERS. SIGNIFICANT DRYING AND RIDGING BEGIN
TO WORK IN FOR SATURDAY...SO PRECIP SHOULD NOT BE A PROBLEM. NIGH
LOWS WILL BE COOL FOR SURE...BUT CLOUD COVER WILL BE THE DETERMINING
FACTOR ON HOW COOL. TEMPERATURE RECOVERY BEGINS SUNDAY AS THE HIGH
SHIFTS EAST AND WE GET RETURN FLOW. THE NEXT FRONTAL SYSTEM WILL BE
ACROSS THE NORTHERN AND CENTRAL LAKES COME SUNDAY.
&&
.AVIATION /07Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE AND DRY AIRMASS JUST TO OUR NORTHEAST. TO OUR
SOUTHWEST THERE IS A MORE HUMID AIRMASS AND A DEVELOPING WARM
FRONT. THE DRY AIR IN COMBINATION WITH ALL OF THE HIGH CLOUD
PRESENTLY OVER THE AREA SHOULD LIMIT ANY EARLY MORNING BR ISSUES.
ALREADY STARTING TO SEE SOME MID CLOUD DEVELOPMENT OFF THE WARM
FRONT. OBSERVATIONS ARE COMING IN BETWEEN 5K AND 7K FEET. WITH
THAT HAVE REMOVED THE MENTIONS OF 3K FEET LOCALLY AND RAISED THAT
TO VFR. WARM FRONT WILL PUSH NORTHEAST TODAY AND BRING EASTERLY
WINDS AROUND TO THE SOUTH. MOST OF OUR FORECAST MODELS WANT TO
DEVELOP A FEW SHOWERS/POSSIBLY A TS/ ACROSS THE AREA THIS
AFTERNOON. HAVE CONTINUED WITH THE SHRA MENTION IN PROB GROUPS.
RIDGE REALLY BUILDS IN MONDAY EVENING AND PRECIP CHANCES ARE
EXPECTED TO BE OVER.
OUTLOOK...NON VFR WITH POSSIBLE SHOWERS/THUNDERSTORMS WEDNESDAY
THROUGH THURSDAY. MAY HAVE SOME NON VFR CEILINGS ACROSS THE
SNOWBELT THURSDAY AND FRIDAY.
&&
.MARINE...
SOUTHERLY FLOW TODAY AND A RELATIVELY NICE DAY ON THE LAKE. THERE
MAY BE A SHOWER OR THUNDERSTORM TODAY AS A WARM FRONT PUSHES
NORTHEAST ACROSS THE LAKE. FLOW COMES AROUND TO THE SOUTHWEST
TUESDAY AND PICKS UP ENOUGH THAT A SMALL CRAFT ADVISORY MAY BE
NEEDED ALONG THE EAST HALF/END. WINDS BEGIN TO DECREASE TUESDAY
NIGHT INTO WEDNESDAY AS A WEAKENING COLD FRONT BEGINS TO SINK SOUTH
ACROSS THE CENTRAL LAKES. WINDS SHIFT TO THE NORTHWEST BY THURSDAY
MORNING. SOME OF THE BETTER COLD AIR ADVECTION IS DELAYED UNTIL
FRIDAY. AT THAT POINT WINDS WILL PICK UP AND SMALL CRAFT CONDITIONS
WILL BE LIKELY. A MUCH COOLER AIRMASS WILL BRING LAKE EFFECT RAIN
SHOWERS TOO.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...OUDEMAN
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
227 AM EDT MON SEP 9 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE POCONOS/CATSKILLS THIS MORNING
WILL SLIDE OFF THE NORTHERN MID-ATLANTIC COAST LATER TODAY. A
DEVELOPING SOUTHERLY RETURN FLOW AROUND THE WESTERN PERIPHERY OF
THE DEPARTING HIGH PRESSURE SYSTEM WILL LIFT A WARM FRONT NORTHWARD
ACROSS THE AREA LATE TONIGHT INTO EARLY TUESDAY. HOT AND HUMID
SUMMER-LIKE CONDITIONS ARE EXPECTED THROUGH MIDWEEK BEFORE A COLD
FRONT MOVES THROUGH ON THURSDAY. FAIR WEATHER AND SEASONABLY COOL
TEMPERATURES SHOULD RETURN BY FRIDAY AND LAST INTO THE WEEKEND..AS
ANOTHER CANADIAN AIR MASS ACCOMPANIES HIGH PRESSURE BACK INTO THE
REGION.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
1022 MB SFC HIGH WAS CENTERED ACROSS SCENT NEW YORK AT 06Z. THE
MODIFIED CANADIAN AIR MASS ACCOMPANYING THIS HIGH PRES SYSTEM IS NOT
QUITE AS COOL AND CHILLY AS THE ONE OF A FEW DAYS PAST. HOWEVER...
STILL CANT RULE OUT SOME PATCHY FROST ACROSS THE COLDER POCKETS OF
THE NRN MTNS WHERE MINS SHOULD DIP INTO THE UPPER 30S. MID 40S TO
LOW 50S WILL BE COMMON ELSEWHERE. ALSO LOOK FOR FOG TO FORM IN THE
NRN RIVER/STREAM VALLEYS TOWARDS DAWN...AS WIND BECOMES NEARLY CALM.
EARLY MORNING IR LOOP SHOWS THIN CIRRUS SPILLING SE FROM THE LOWER
GLAKES REGION AND SPREAD ACROSS MUCH OF CENTRAL PENN.
THE SFC COLD FRONTAL BOUNDARY HAS PUSHED WELL TO THE SOUTH OF THE
MASON/DIXON LINE. HOWEVER...THE SHALLOW BOUNDARY AND MOISTURE IN THE
925-850 MB LAYER IS BEGINNING TO NOSE BACK NORTH INTO SCENT PENN AND
THE LAUREL HIGHLANDS...ACCOMPANIED BY A BKN-OVC STRATOCU DECK OF
3.5-5 KFT AGL. MORE ON THIS ASPECT OF TODAY`S WEATHER BELOW.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM TUESDAY/...
THE SFC HIGH IS EXPECTED TO QUICKLY SLIDE OFF THE EAST COAST DURING
THE DAY TODAY SETTING UP A RETURN FLOW OF AIR OUT OF THE SOUTH.
00Z NAM...AND 05Z RUC INDICATES THAT WE/LL SEE THE HIGHER MOISTURE
IN THE 925-850 MB LAYER ADVECT NNE DURING THE DAY TODAY...RESULTING
IN INCREASING /MAINLY HIGH-BASED/ STRATOCU CLOUDS ACROSS THE SW HALF
OF THE CWA DURING THE MID TO LATE MORNING HOURS....AND DURING THE
AFTERNOON HOURS ACROSS THE SUSQUEHANNA`S MIDDLE AND WEST BRANCH
COMMUNITIES.
SREF/GEFS BOTH SHOW PWATS OF 1-2 SD ABOVE NORMAL SLIDING BACK INTO
WESTERN PA BY THE END OF THE DAY. SHORT RANGE OPERATIONAL MODELS
SHOW THE CHANCE FOR SHOWERS OVER MY FAR WESTERN ZONES BEFORE
NIGHT-FALL. SREF AND GEFS BOTH SHOW SMALL CHANCES FOR RAIN...THE
SREF BEING SLIGHTLY MORE AGGRESSIVE THAN THE GEFS. IT ALL POINTS TO
SCATTERED SHOWERS OR EVEN A THUNDERSTORM BY LATE DAY.
MDL DATA INDICATES THERE WILL BE VARYING AMTS OF CIRRUS ACROSS THE
AREA TODAY...SO HAVE KEPT MAX TEMPS A BIT LOWER THAN ENS MEAN
925MB TEMPS COULD SUPPORT WITH FCST HIGHS IN THE 70-75F RANGE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
NOT A LOT OF CHANGE FROM YESTERDAY. LOOKING AT A LARGE AREA OF
HIGH PRESSURE BUILDING ACROSS THE REGION...WITH A SLAB OF HOT
AIR FROM THE HIGH SOUTHERN PLAINS MOVING EASTWARD. WITH AN EML
AIRMASS IN PLACE...AND A TENDENCY TO CAP ANY CONVECTION...THINK
VERY LITTLE CHC OF RAIN WITH WARM FRONT LATE MONDAY NIGHT...AND
NOT MUCH IN THE WARM SECTOR ON WED...MAYBE A FEW STORMS LATE. DID
UP TEMPS SOME AND LOWER POPS A LITTLE.
HIGHEST CHC OF STORMS WILL BE ON THU...AS COLD FRONT NEARS.
COMPLEX FRONT...MORE LIKE 2 COLD FRONTS.
COLDER AIR FOR LATE IN THE WEEK...BUT THIS IS COMPLEX TOO.
EC RUNS HINT AT LESS HIGH PRESSURE MAY BUILD IN...AND UPPER LVL
TROUGH COULD TRY TO CLOSE OFF JUST EAST OF THIS AREA.
AS FAR AS LAKE EFFECT GOES...HARD TO SEE MUCH...PERHAPS SOME
LATER ON FRIDAY...AS COLD AIR DEEPENS...AND WINDS ALOFT BECOME
MORE NW.
THE MAIN STORY WILL BE THE HEAT. MANY SPOTS WILL LIKELY SEE
90 DEGREES...BETWEEN TUE AND LATE THU...AS PLUS 18 DEGREE AIR
OR HIGHER MOVES IN AT 850 MB ON WESTERLY FLOW. NAM STILL THE
WARMEST MODEL.
NOT SURE I BUY INTO THE HIGH DEWPOINTS ON TUE...ETC...WITH THIS
AIRMASS...GIVEN WHERE THE AIRMASS COMES FROM. WHILE THERE WILL BE
POTENTIAL FOR STRONG STORMS AT SOME POINT...THIS WILL LARGELY
DEPEND ON HOW MUCH LOW LVL MOISTURE WORKS INTO THE AREA. ANYWAY...
ENJOY THE LATE SUMMER WEATHER...AS WE MAKE UP FOR WHAT WAS A WET
EARLY SUMMER.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER NE PA/SE NY WILL MOVE OFF THE NRN MID-ATLC
COAST BY 00Z. A DEVELOPING S-SWLY FLOW WILL LIFT A WARM FNT ACRS
THE AIRSPACE LATE TONIGHT INTO EARLY TUESDAY. A COLD FRONT WILL
APPROACH THE REGION FROM THE GREAT LAKES ON WED BEFORE CROSSING
THE AIRSPACE ON THURSDAY. HIGH PRESSURE WILL RETURN BEHIND THE
FRONT ON FRIDAY AND REMAIN IN CONTROL INTO THE WEEKEND.
IR SATL SHOWS SCT-BKN CIRRUS STREAMING SWD OVER PA EARLY THIS
MORNING. THERE ALSO APPEARS TO BE SOME LOWER CLOUDS DEVELOPING
OVER NRN VA AND THE WV/MD PNHDLES AS THE LLVL FLOW VEERS TO THE
ESE. THESE LOWER CLOUDS/VFR CIGS MAY TRY TO CREEP NORTH INTO
S-CNTRL PA EARLY THIS MORNING. SOME RADIATIONAL FOG MAY REDUCE VIS
AT BFD AND WILL HANDLE WITH AMDS GIVEN LOW CONFIDENCE. OTHERWISE
EXPECT VFR TO PREVAIL THRU THE EVE HOURS WITH SFC WINDS SHIFTING
FROM ENE TO SSE-SSW. MVFR CIGS ARE LKLY TO DEVELOP ACRS THE SERN
TERMINALS LATER TNT INTO EARLY TUESDAY.
OUTLOOK...
TUE...AM LOW CLOUDS SOUTH/EAST. ISOLD PM TSTM IMPACTS PSBL.
WED...SCT PM TSTM IMPACTS PSBL.
THU...SCT-NMRS TSTM IMPACTS PSBL WITH COLD FROPA.
FRI...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/LAMBERT/STEINBUGL
NEAR TERM...FITZGERALD/LAMBERT
SHORT TERM...FITZGERALD/LAMBERT
LONG TERM...MARTIN
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1221 AM CDT MON SEP 9 2013
.UPDATE...
AVIATION DISCUSSION HAS BEEN UPDATED FOR THE 06Z TAF ISSUANCE.
A LOT OF FORECAST UNCERTAINTY AT THIS TIME. 18Z MODEL DATA IS MUCH
MORE BULLISH WITH LLJ BEING DISPLACED FURTHER EAST ACROSS THE
ABERDEEN CWA. THE HRRR DOES INDICATE AN INCREASE IN ELEVATED
CONVECTION DURING THE MID TO LATE EVENING...AND GIVEN MODEL
CHANGES WILL ACCEPT THAT AND INCREASE POPS A LITTLE. FURTHER WEST
IT APPEARS THERE WILL STILL BE SOME OPPORTUNITY FOR AN MCS OR TWO
COMING OFF THE HIGH PLAINS AND EAST ACROSS THE CWA OVERNIGHT. HRRR
CONTINUES TO BE QUITE BULLISH WITH THIS PROGNOSTICATION AND THUS
WILL MAINTAIN RELATIVELY HIGH POPS. TEMPERATURES ARE OKAY. UPDATES
OUT SOON.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH TUESDAY AM
WHILE PRECIPITATION HAS DISSIPATED...CONVECTIVE DEBRIS CONTINUES
TO MUDDY WHAT WAS ALREADY A COMPLEX FORECAST. DAYTIME HEATING IS
GREATEST ACROSS NORTHWEST COUNTIES...UNDER WHICH THE CAP IS THE
WEAKEST...WITH H7 TEMPERATURES ONLY BETWEEN +11 AND +12C. THE
MAIN SHORTWAVE IS STILL FAR TO THE WEST...WITH WARM ADVECTION
ALOFT. THERE IS STILL THE POTENTIAL FOR A SURFACE BASED STORM OR
TWO TO FORM ALONG THE ND/SD BORDER AND PUSH EAST...WEAKENING AS H7
TEMPERATURES WARM AND IT ENCOUNTERS MORE CLOUDY/LESS UNSTABLE AIR
IN THE EAST...AND IN FACT SOME OF THE HIGH RES GUIDANCE HINTS AT
SUCH. OTHERWISE...CONVECTION TODAY WILL BE LIMITED TO ELEVATED
WEAK STORMS OVER CENTRAL/WESTERN SD WHERE H7 WARM ADVECTION
STEEPENS MID LEVEL LAPSE RATES...AND SOME OF THE HIGH RES GUIDANCE
HAS SUGGESTED THIS OUTCOME. OF GREATEST CONCERN CONTINUES TO BE AS
THE SHORTWAVE APPROACHES...AND TEMPERATURES ALOFT COOL...WITH
INCREASING LOW LEVEL JET SUPPORT. STORMS IN THIS ENVIRONMENT FAVOR
SLOW EAST/NORTHEAST STORM MOTION...WITH NORTH DAKOTA GETTING THE
BEST COVERAGE...STILL LOOKING LIKE SCATTERED COVERAGE THIS SIDE OF
THE BORDER. GIVEN THE HEAVY RAIN LAST NIGHT IN CORSON
COUNTY...WENT FOR A FLASH FLOOD WATCH. STORMS PUSH EAST AND
DISSIPATE MONDAY AM. THE FRONT IS NOW PROGGED TO PUSH ALL THE WAY
THROUGH THE CWA BY MID DAY...WITH THE CAP IN PLACE FARTHER EAST
...PRE-FRONTAL CONVECTIVE ACTIVITY APPEARS UNLIKELY IN THE CWA. IN
THE POST FRONTAL ENVIRONMENT...COOLING ALOFT AND PLENTY OF DAYTIME
HEATING SUGGEST A CONTINUED THREAT FOR STORMS...WITH STRAIGHT
LINE HODOGRAPHS. MAIN QUESTION REVOLVES AROUND INSTABILITY AS WILL
SEE LOW LEVEL DRY AIR ADVECTION AS WELL.
.LONG TERM...TUESDAY THROUGH SUNDAY
BULK OF THE EXTENDED PERIOD LOOKS DRY AT THIS POINT. ON TUESDAY
DRIER AIR WILL BE FILTERING INTO THE REGION WITH NORTHWEST FLOW
ALOFT. CONDITIONS LOOK DRY ALL THE WAY THROUGH THE FIRST HALF OF
FRIDAY AS SFC HIGH PRESSURE BEGINS BUILDING SOUTH INTO THE AREA BY
THURSDAY. COOLER AIR ARRIVES ON THURSDAY AS WELL...SO THE 80S FOR
HIGHS ON TUESDAY AND WEDNESDAY WILL BE REPLACED BY 70S ON THURSDAY
AND FRIDAY. THE ONLY REAL SHOT FOR PRECIP DURING THE EXTENDED
FORECAST IS FRIDAY NIGHT THROUGH SATURDAY NIGHT AS SHORTWAVE
ENERGY MOVES INTO THE NORTHERN PLAINS AROUND THE UPPER RIDGE.
MODELS HAVE TRENDED FURTHER SOUTH WITH THIS FEATURE INITIALLY ON
FRIDAY...WITH MODELS SHOWING MOST QPF ACROSS NEBRASKA AND SOUTHERN
SOUTH DAKOTA. FAIRLY GOOD AGREEMENT ACTUALLY IN BRINGING PRECIP
INTO THE EASTERN CWA DURING THE DAY SATURDAY. FOR NOW HAVE
ACCEPTED ALLBLEND POPS WHICH HAVE 30S/40S FOR POPS FRIDAY NIGHT
THROUGH SATURDAY WHICH LOOKS GOOD AT THIS POINT.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A MIX OF CONDITIONS IS EXPECTED ACROSS THE REGION THROUGH MONDAY.
A MIX OF VFR/MVFR CIGS IS EXPECTED AT KMBG/KPIR AS STORMS MOVE
THROUGH THE AREA EARLY THIS MORNING. FURTHER EAST AT KATY AN IFR
DECK OF CLOUDS WILL LIKELY PERSIST THROUGH THE MORNING HOURS ON
MONDAY...ALONG WITH MVFR FOG. KABR WILL LIKELY SHARE IN SOME IFR
CIGS MVFR VSBYS OVERNIGHT...ALONG WITH SOME STORMS LATE. ANY
STORMS COULD PRODUCE PERIODS OF IFR CONDITIONS WHEN THEY MOVE
THROUGH.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...FLASH FLOOD WATCH UNTIL 6 AM MDT MONDAY FOR CORSON.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...CONNELLY
LONG TERM...TMT
AVIATION...TDK
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
257 AM CDT MON SEP 9 2013
.DISCUSSION...
WEAK VERY SUBTLE SURFACE BOUNDARY EXTENDS FROM SAINT LOUIS DOWN
THROUGH FAR WESTERN KENTUCKY INTO SOUTHERN MIDDLE TENNESSEE. WEAK
SHORT WAVE AT THE MID LEVELS OVER FAR WESTERN KENTUCKY CAN BE SEEN
IN 00Z EURO AT 06Z AND TO SOME EXTENT IN THE LASTEST RUC LOOP OF 700
MBAR COLD TEMP AXIS. AGAIN VERY SUBTLE FEATURES. ISOLATED CONVECTION
DEVELOPED JUST AFTER MIDNIGHT IN FAR NORTHWEST MIDDLE TENNESSEE
AND HAS MOVED LITTLE LAST COUPLE OF HOURS. 500 MBAR HIGH TO OUR
WEST WILL WORK EASTWARD TODAY KEEPING SUBSIDENCE ACROSS THE AREA
AND WITH LITTLE IN THE WAY OF FORCING SO AM EXPECTING TO SEE ONLY
ISOLATED CONVECTION ONCE AGAIN. THINK AREAS WEST OF INTERSTATE 65
MIGHT BE FAVORED BUT AGAIN LOW POPS. SURFACE BOUNDARY WILL LIFT
NORTH TODAY WHILE SHORT WAVE DAMPS OUT. THIS WILL PLACE MID STATE
PRETTY MUCH IN THE GRIPS OF UPPER LEVEL RIDGING WITH LOW POP
CHANCES FOR CONVECTION BOTH DURING THE DAY AND NOCTURNALLY AT
LEAST THROUGH WEDNESDAY. BY THURSDAY A SURFACE FRONT WILL BE
MAKING ITS WAY SOUTHWARD FROM GREAT LAKES REGION AND THIS WILL
INCREASE POPS FOR THURSDAY AND THURSDAY NIGHT. WITH ALL THE
RIDGING IN PLACE OF RECENT DAYS AND CONTINUED OFF CONTINENT WIND
FLOW I JUST DONT SEE MUCH IN THE WAY OF MOISTURE TO FEED THIS
SOUTH BOUND SYSTEM SO AM EXPECTING RAINFALL AMOUNTS TO LIKELY BE
LOW. FRONT GETS SOUTH OF MID STATE ON FRIDAY WITH 1024 SURFACE
HIGH CENTERED OVER LAKE SUPERIOR. COOLER AND MORE SEASONABLE TEMPS
WILL FOLLOW FRONTAL PASSAGE. SURFACE HIGH WILL RIDGE DOWN ACROSS
THE MID STATE THROUGH THE WEEKEND.
AS FOR TEMPS...MET IS RUNNING 2 TO 4 DEGREES COOLER THAN MAV FOR
DAYTIME HIGHS THROUGH WEDNESDAY AND KEEPS TRYING TO GO TOWARD
CLIMATOLOGY WHILE MAV IS WANTING TO KEEP THINGS MORE HEATED. I
BASICALLY KNOCKED ONE TO TWO DEGREES OFF THE MAV FOR DAYTIME HIGHS
THROUGH WEDNESDAY OR CLOSER TO AVERAGE OF THE TWO MODELS. BOTH MET
AND MAV ARE CLOSE ON NIGHTTIME LOWS THROUGH WEDNESDAY SO I FOLLOWED.
FOLLOWING FRONTAL PASSAGE EXPECT HIGHS ON FRIDAY TO BE A GOOD 10
DEGREES COOLER THAN WHAT WE HAVE BEEN SEEING. TEMPS FRIDAY THROUGH
THE WEEKEND WILL BE IN THE LOW TO MID 80S WITH MID AND UPPER 70S
ALONG THE UPPER CUMBERLAND.
BOYD
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 92 71 93 71 / 20 10 20 20
CLARKSVILLE 91 69 92 69 / 20 10 20 20
CROSSVILLE 85 64 86 65 / 20 10 20 20
COLUMBIA 93 69 93 70 / 20 10 20 20
LAWRENCEBURG 93 67 92 68 / 20 10 20 20
WAVERLY 92 68 93 69 / 20 10 20 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
BOYD
01
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1103 AM EDT MON SEP 9 2013
.UPDATE...
FORECAST IS ON TRACK SO ONLY A FEW MINOR CHANGES IN THE UPDATE TO
ACCOUNT FOR HOURLY TRENDS. MAIN UNCERTAINTY THIS AFTERNOON IS IN
TERMS OF PRECIP. HRRR MAY BE OVER DOING CONVECTION TODAY AND IS
TRYING TO DEVELOP ACTIVITY ACROSS EVEN THE ATL METRO AREA BY 17Z
HOWEVER THE OTHER MODELS SUCH AS THE LOCAL WRF ARE VERY LIMITED ON
CONVECTIVE ACTIVITY TODAY. THINK THE BEST CHANCES REMAIN ACROSS
FAR NORTH GEORGIA AND IN PARTICULAR ACROSS NORTHWEST
GEORGIA...CLOSER TO THE SHORTWAVE.
11
&&
.PREV DISCUSSION...
SHORT TERM /TODAY THROUGH TONIGHT/...
/ISSUED AT 345 AM EDT MON SEP 9 2013/
ISOLATED SHOWERS CONTINUE TO DEVELOP ACROSS PARTS OF CENTRAL GA
EARLY THIS MORNING AND MAY NEED TO CONTINUE SMALL CHANCE POPS INTO
THE MORNING HOURS. SOME SLIGHT DIFFERENCES BETWEEN THE GFS AND THE
NAM/ECMWF MIX FOR THE SHORT TERM...MAINLY IN THE LOCATION OF THE
DEEPEST MOISTURE. ALL MODELS SHOW A SHORT WAVE OVER TN. THE GFS
HOLDS THE S/W OVER TN/NRN AL WHILE THE NAM/ECMWF BRINGS IT TO THE
NORTHWEST GA BORDER ALONG WITH SOME DEEPER MOISTURE. WITH THE RETURN
OF AN EASTERLY FLOW BRINGING IN ATLANTIC MOISTURE...THE RISK OF
CONVECTION IS SLIGHTLY GREATER THAN SUNDAY WITH A BETTER CHANCE NEAR
THE VICINITY OF THE S/W AND THEREFORE HAVE GONE WITH CHANCE POPS
OVER NORTHWEST GA. CONVECTION SHOULD DISSIPATE AFTER SUNSET. WINDS
WILL BE EASTERLY THROUGH THE SHORT TERM AND THEREFORE EXPECT MAX
TEMPS TODAY TO BE AT OR PERHAPS A DEGREE OR TWO LOWER THAN SUNDAYS
MAX TEMPS.
17
LONG TERM /TUESDAY THROUGH SUNDAY/...
/ISSUED AT 345 AM EDT MON SEP 9 2013/
A WEAKNESS IN THE UPPER RIDGE AND ASSOCIATED MOISTURE WILL GIVE SOME
CHANCES FOR SHOWERS AND THUNDERSTORMS OVER MAINLY FAR N GA TUESDAY
AFTERNOON. NOT SURE THE MODELS HAVE A GOOD HANDLE ON THIS AND THERE
COULD BE SOME CHANCE FOR MEASURABLE PRECIP TUESDAY MORNING. OVERALL
INSTABILITY IS WEAK AND THE PRECIP COULD BE ONLY SHOWERS.
THE SAME WEAKNESS THAT DOES NOT APPEAR TO BE HANDLED VERY WELL BY
THE MODELS AND ASSOCIATED MOISTURE COULD CAUSE SOME SHOWERS AND
THUNDERSTORMS OVER MAINLY FAR N GA ON WEDNESDAY AFTERNOON AND MOST
SO OVER THE NE MOUNTAINS WHERE THE BEST INSTABILITY IS FORECAST.
A COLD FRONT APPROACHES N GA LATE THURSDAY GIVING A CHANCE OF
SHOWERS AND THUNDERSTORMS OVER MAINLY N GA. FRONT EXPECTED TO MOVE
INTO N GA THURSDAY NIGHT/FRIDAY MORNING AND TO S GA SATURDAY
MORNING. THIS WILL CONTINUE THE CHANCE OF SHOWERS AND THUNDERSTORMS
FOR MUCH OF THE AREA ON FRIDAY AND MAINLY FOR CENTRAL GA ON
SATURDAY. MODELS INCONSISTENT WITH MOISTURE RETURN ON SATURDAY NIGHT
AND SUNDAY WITH THE GFS INCREASING SIGNIFICANT MOISTURE MUCH MORE
THAN THE EUROPEAN FROM STRONGER EAST FLOW OFF THE ATLANTIC. DUE TO
THE UNCERTAINTY WILL NEED TO INDICATE SMALL POPS OVER CENTRAL AND
PORTIONS OF N GA FOR SHOWERS ONLY ON SUNDAY.
HIGH TEMPERATURES GENERALLY RUNNING SLIGHTLY ABOVE NORMAL TUESDAY
THROUGH THURSDAY THEN AROUND 5 DEGREES BELOW NORMAL SATURDAY AND
SUNDAY.
BDL
AVIATION...
12Z UPDATE...
/ISSUED 730 AM EDT MON SEP 9 2013/
PATCHY LIGHT FOG WILL DISSIPATE BY 14Z LEAVING VFR CONDITIONS ACROSS
THE FORECAST AREA THROUGH THIS EVENING. CHANCES OF TSRA AT THE TAF
SITES THIS AFTERNOON ARE LOW ENOUGH TO LEAVE OUT OF THE TAF FOR NOW.
WINDS ARE NOW NORTHEAST AND THEY SHOULD STAY EASTERLY FOR THE REST
OF THE FORECAST PERIOD WITH SPEEDS LESS THAN 10 KTS.
//ATL CONFIDENCE...12Z UPDATE...
HIGH CONFIDENCE ALL ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 89 66 89 68 / 20 20 10 0
ATLANTA 90 70 88 69 / 20 20 10 0
BLAIRSVILLE 82 64 85 64 / 20 20 20 10
CARTERSVILLE 90 66 89 65 / 20 20 20 10
COLUMBUS 93 71 90 70 / 20 20 10 0
GAINESVILLE 87 68 88 68 / 20 20 10 10
MACON 92 66 90 68 / 20 10 5 0
ROME 91 67 90 66 / 30 20 30 10
PEACHTREE CITY 90 66 88 66 / 20 20 10 0
VIDALIA 91 68 91 69 / 20 10 5 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...11
LONG TERM....39
AVIATION...11
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
951 AM EDT MON SEP 9 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL DISSIPATE OVER OR NEAR THE AREA TODAY AS HIGH
PRESSURE BUILDS IN FROM THE NORTH. THIS AREA OF HIGH PRESSURE WILL
THEN PREVAIL THROUGH THE MIDDLE OF THE WEEK BEFORE A BACKDOOR COLD
FRONT DROPS ACROSS THE AREA FRIDAY AND FRIDAY NIGHT. COOLER HIGH
PRESSURE WILL THEN BUILD INTO THE REGION FROM THE NORTH INTO EARLY
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A VERY WEAK BACKDOOR FRONT MOVING SOUTH ACROSS NORTH CAROLINA WILL
DISSIPATE NORTH OF THE AREA TODAY. LIGHT WINDS WILL BECOME ONSHORE
THIS AFTERNOON AS HIGH PRESSURE BUILDS SOUTH AND A MODEST SEA
BREEZE CIRCULATION TAKES HOLD. A NUMBER OF THE HIGHER RESOLUTION
MODELS INCLUDING THE H3R...4KM NSSL WRF AND RAP ARE SPITTING OUT
ISOLATED SHOWERS/TSTMS ALONG THE SEA BREEZE FOR 1-2 HOURS THIS
AFTERNOON. NOT COMPLETELY CONVINCED ACTIVITY WILL FIRE AS IT
APPEARS THEY MAY BE OVER DEVELOPING THE CUMULUS FIELD ALONG THE
LEADING EDGE OF THE THERMALLY DIRECT CIRCULATION. PLAN TO KEEP THE
FORECAST DRY FOR NOW...ALTHOUGH SOME SMALL...SINGLE DIGIT GRIDDED
POPS WILL BE PLACED ALONG AND AHEAD OF THE SEA BREEZE FOR THE
AFTERNOON HOURS. SHOULD ANY SHOWERS/TSTMS DEVELOP...THEY WILL BE
SHORT LIVED GIVEN THE AMOUNT OF DRY AIR NOTED ALOFT. OVER THE
WATER...AN ISOLATED SHOWER WILL BE POSSIBLE THROUGH LATE THIS
MORNING ALONG A LINGERING LAND BREEZE CIRCULATION THAT IS NOTED
ABOUT 5 NM OFFSHORE.
A DECENT CUMULUS FIELD DEVELOP PRIOR TO NOON...BUT SHOULD CLEAR
OUT FROM EAST-WEST AS THE SEA BREEZE MOVES INLAND. HIGHS WILL FROM
THE LOWER 90S INLAND TO THE MID 80S AT THE BEACHES LOOK ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
TONIGHT...HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE NORTH
WITH DRY CONDITIONS EXPECTED. JUST A REAL SMALL CHANCE OF A SHOWER
NEAR THE COAST LATE AS A WEAK COASTAL TROUGH ATTEMPTS TO DEVELOP.
OTHERWISE...LOWS SHOULD RANGE FROM THE UPPER 60S INLAND TO THE
MID 70S AROUND THE COAST.
TUESDAY THROUGH THURSDAY...EXPANSIVE UPPER LEVEL RIDGING WILL
PREVAIL OVER THE SOUTHEAST U.S. TUESDAY AND TUESDAY NIGHT...BUT
THEN AN INVERTED UPPER LEVEL TROUGH WILL RETROGRADE TOWARD THE
SOUTHEAST COAST WEDNESDAY AND WEDNESDAY NIGHT CAUSING THE EASTERN
PERIPHERY OF THE RIDGE TO ERODE. A LONGWAVE UPPER LEVEL TROUGH
WILL THEN BEGIN TO BECOME ESTABLISHED OVER THE EASTERN U.S. ON
THURSDAY. MEANWHILE AT THE SURFACE...HIGH PRESSURE WILL BUILD INTO
THE REGION FROM THE NORTH THROUGH WEDNESDAY...WITH THE AXIS OF THE
HIGH SHIFTING SOUTHWARD ACROSS THE AREA ON THURSDAY AS A COLD
FRONT APPROACHES FROM THE NORTHWEST.
STRONG SUBSIDENCE AND A LACK OF DEEP MOISTURE WILL GENERALLY KEEP
RAIN-FREE CONDITIONS IN PLACE. THE EXCEPTION COULD BE ALONG PARTS OF
THE IMMEDIATE SOUTHEAST GEORGIA COAST WHERE ISOLATED CONVECTION
COULD DEVELOP OFFSHORE IN AN AREA OF ENHANCED LOW LEVEL CONVERGENCE
AND SHIFT ONSHORE AT TIMES TUESDAY NIGHT THROUGH THURSDAY.
HIGH TEMPERATURES WILL GENERALLY BE AROUND 90...WITH COOLER
TEMPERATURES ALONG THE IMMEDIATE COAST. RADIATIONAL COOLING WILL BE
SUFFICIENT TO ALLOW TEMPERATURES TO FALL INTO THE UPPER 60S AWAY
FROM THE COAST...WITH A FEW MID 60S POSSIBLE IN WELL SHELTERED
AND/OR LOW LYING AREAS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH THE LONG TERM
PERIOD. A LONGWAVE UPPER LEVEL TROUGH WILL BE THE PREDOMINANT
FEATURE OVER THE EASTERN U.S. THROUGH SATURDAY...BEFORE THE TROUGH
LIFTS OUT AND THE FLOW BECOMES MORE ZONAL LATE IN THE WEEKEND INTO
EARLY NEXT WEEK. AT THE SURFACE...A BACKDOOR COLD FRONT WILL DROP
ACROSS THE AREA FRIDAY INTO FRIDAY NIGHT...THEN STALL OUT JUST SOUTH
OF THE AREA THROUGH THE REMAINDER OF THE LONG TERM PERIOD AS MUCH
COOLER HIGH PRESSURE BUILDS IN FROM THE NORTH.
THERE IS A CHANCE THAT SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE
PASSAGE OF THE COLD FRONT FRIDAY AND FRIDAY NIGHT...AND CONTINUE
INTO SATURDAY ACROSS MUCH OF THE AREA AS THE FRONT STALLS JUST TO
THE SOUTH. PRECIPITATION CHANCES WILL THEN CONTINUE INTO EARLY NEXT
WEEK ACROSS MUCH OF SOUTHEAST GEORGIA WHICH IS IN CLOSER PROXIMITY
TO THE FRONT AND THE DEEPER MOISTURE...WITH SOMEWHAT DRIER
CONDITIONS POSSIBLE FARTHER NORTH INTO PARTS OF SOUTHEAST SOUTH
CAROLINA.
TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH FRIDAY...THEN
COOLER/BELOW TEMPERATURES WILL OCCUR DURING THE REMAINDER OF THE
LONG TERM PERIOD AS A NORTHEAST FLOW DEVELOPS AS HIGH PRESSURE
BUILDS SOUTHWARD INTO THE REGION.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 12Z TUE.
EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS WITH A GREATER
THAN 30 PERCENT CONFIDENCE AT THIS TIME.
&&
.MARINE...
TODAY AND TONIGHT...HIGH PRESSURE WILL BUILD IN FROM THE NORTH
CAUSING WINDS TO SHIFT TO EASTERLY BUT REMAINING 15 KT OR LESS.
WINDS COULD BACK TO MORE NORTHEAST NEAR THE COAST LATE TONIGHT AS
A WEAK COASTAL TROUGH OF LOW PRESSURE TRIES TO DEVELOP. SIGNIFICANT WAVE
HEIGHTS WILL BE UP TO 3 FT WITHIN 20 NM AND UP TO 4 FT BEYOND 20
NM...DOMINATED BY A 8-9 SECOND E/SE SWELL...AT LEAST THROUGH
TODAY.
TUESDAY THROUGH SATURDAY...HIGH PRESSURE WILL BUILD OVER THE
REGION FROM THE NORTH THROUGH WEDNESDAY...MAINTAINING AN ONSHORE
FLOW OVER THE WATERS WITH WIND SPEEDS GENERALLY 15 KT OR LESS. THE
FLOW WILL BECOME MORE SOUTHERLY ON THURSDAY AHEAD OF AN APPROACHING
COLD FRONT...WHICH IS EXPECTED TO DROP ACROSS THE WATERS FRIDAY AND
FRIDAY NIGHT SHIFTING THE WINDS NORTHEAST IN ITS WAKE. A STRONG
NORTHEAST SURGE WILL THEN OCCUR FRIDAY NIGHT AND SATURDAY...LIKELY
RESULTING IN SMALL CRAFT ADVISORY CONDITIONS OVER PORTIONS OF THE
WATERS. SEAS WILL GENERALLY BE NO HIGHER THAN 2-4 FT...GREATEST OVER
THE OUTER GEORGIA WATERS...THROUGH FRIDAY BEFORE INCREASING A COUPLE
OF FEET SATURDAY AS THE STRONG NORTHEAST FLOW DEVELOPS AND THE FETCH
INCREASES.
WATERSPOUTS...VISIBLE SATELLITE AND SURFACE OBSERVATIONS SHOW
TOWERING CUMULUS BEGINNING TO DEVELOP ALONG A WELL-DEFINED LAND
BREEZE NOTED ABOUT 5 NAM OFFSHORE. WIND PROFILES SUPPORT A RISK
FOR WATERSPOUTS THROUGH ABOUT NOON. A MARINE WEATHER STATEMENT
WILL BE ISSUED TO HIGHLIGHT THIS RISK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
945 AM EDT MON SEP 9 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL DISSIPATE OVER OR NEAR THE AREA TODAY AS HIGH
PRESSURE BUILDS IN FROM THE NORTH. THIS AREA OF HIGH PRESSURE WILL
THEN PREVAIL THROUGH THE MIDDLE OF THE WEEK BEFORE A BACKDOOR COLD
FRONT DROPS ACROSS THE AREA FRIDAY AND FRIDAY NIGHT. COOLER HIGH
PRESSURE WILL THEN BUILD INTO THE REGION FROM THE NORTH INTO EARLY
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A VERY WEAK BACKDOOR FRONT MOVING SOUTH ACROSS NORTH CAROLINA WILL
DISSIPATE NORTH OF THE AREA TODAY. LIGHT WINDS WILL BECOME ONSHORE
THIS AFTERNOON AS HIGH PRESSURE BUILDS SOUTH AND A MODEST SEA
BREEZE CIRCULATION TAKES HOLD. A NUMBER OF THE HIGHER RESOLUTION
MODELS INCLUDING THE H3R...4KM NSSL WRF AND RAP ARE SPITTING OUT
ISOLATED SHOWERS/TSTMS ALONG THE SEA BREEZE FOR 1-2 HOURS THIS
AFTERNOON. NOT COMPLETELY CONVINCED ACTIVITY WILL FIRE AS IT
APPEARS THEY MAY BE OVER DEVELOPING THE CUMULUS FIELD ALONG THE
LEADING EDGE OF THE THERMALLY DIRECT CIRCULATION. PLAN TO KEEP THE
FORECAST DRY FOR NOW...ALTHOUGH SOME SMALL...SINGLE DIGIT GRIDDED
POPS WILL BE PLACED ALONG AND AHEAD OF THE SEA BREEZE FOR THE
AFTERNOON HOURS. SHOULD ANY SHOWERS/TSTMS DEVELOP...THEY WILL BE
SHORT LIVED GIVEN THE AMOUNT OF DRY AIR NOTED ALOFT. OVER THE
WATER...AN ISOLATED SHOWER WILL BE POSSIBLE THROUGH LATE THIS
MORNING ALONG A LINGERING LAND BREEZE CIRCULATION THAT IS NOTED
ABOUT 5 NM OFFSHORE.
A DECENT CUMULUS FIELD DEVELOP PRIOR TO NOON...BUT SHOULD CLEAR
OUT FROM EAST-WEST AS THE SEA BREEZE MOVES INLAND. HIGHS WILL FROM
THE LOWER 90S INLAND TO THE MID 80S AT THE BEACHES LOOK ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
TONIGHT...HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE NORTH
WITH DRY CONDITIONS EXPECTED. JUST A REAL SMALL CHANCE OF A SHOWER
NEAR THE COAST LATE AS A WEAK COASTAL TROUGH ATTEMPTS TO DEVELOP.
OTHERWISE...LOWS SHOULD RANGE FROM THE UPPER 60S INLAND TO THE
MID 70S AROUND THE COAST.
TUESDAY THROUGH THURSDAY...EXPANSIVE UPPER LEVEL RIDGING WILL
PREVAIL OVER THE SOUTHEAST U.S. TUESDAY AND TUESDAY NIGHT...BUT
THEN AN INVERTED UPPER LEVEL TROUGH WILL RETROGRADE TOWARD THE
SOUTHEAST COAST WEDNESDAY AND WEDNESDAY NIGHT CAUSING THE EASTERN
PERIPHERY OF THE RIDGE TO ERODE. A LONGWAVE UPPER LEVEL TROUGH
WILL THEN BEGIN TO BECOME ESTABLISHED OVER THE EASTERN U.S. ON
THURSDAY. MEANWHILE AT THE SURFACE...HIGH PRESSURE WILL BUILD INTO
THE REGION FROM THE NORTH THROUGH WEDNESDAY...WITH THE AXIS OF THE
HIGH SHIFTING SOUTHWARD ACROSS THE AREA ON THURSDAY AS A COLD
FRONT APPROACHES FROM THE NORTHWEST.
STRONG SUBSIDENCE AND A LACK OF DEEP MOISTURE WILL GENERALLY KEEP
RAIN-FREE CONDITIONS IN PLACE. THE EXCEPTION COULD BE ALONG PARTS OF
THE IMMEDIATE SOUTHEAST GEORGIA COAST WHERE ISOLATED CONVECTION
COULD DEVELOP OFFSHORE IN AN AREA OF ENHANCED LOW LEVEL CONVERGENCE
AND SHIFT ONSHORE AT TIMES TUESDAY NIGHT THROUGH THURSDAY.
HIGH TEMPERATURES WILL GENERALLY BE AROUND 90...WITH COOLER
TEMPERATURES ALONG THE IMMEDIATE COAST. RADIATIONAL COOLING WILL BE
SUFFICIENT TO ALLOW TEMPERATURES TO FALL INTO THE UPPER 60S AWAY
FROM THE COAST...WITH A FEW MID 60S POSSIBLE IN WELL SHELTERED
AND/OR LOW LYING AREAS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH THE LONG TERM
PERIOD. A LONGWAVE UPPER LEVEL TROUGH WILL BE THE PREDOMINANT
FEATURE OVER THE EASTERN U.S. THROUGH SATURDAY...BEFORE THE TROUGH
LIFTS OUT AND THE FLOW BECOMES MORE ZONAL LATE IN THE WEEKEND INTO
EARLY NEXT WEEK. AT THE SURFACE...A BACKDOOR COLD FRONT WILL DROP
ACROSS THE AREA FRIDAY INTO FRIDAY NIGHT...THEN STALL OUT JUST SOUTH
OF THE AREA THROUGH THE REMAINDER OF THE LONG TERM PERIOD AS MUCH
COOLER HIGH PRESSURE BUILDS IN FROM THE NORTH.
THERE IS A CHANCE THAT SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE
PASSAGE OF THE COLD FRONT FRIDAY AND FRIDAY NIGHT...AND CONTINUE
INTO SATURDAY ACROSS MUCH OF THE AREA AS THE FRONT STALLS JUST TO
THE SOUTH. PRECIPITATION CHANCES WILL THEN CONTINUE INTO EARLY NEXT
WEEK ACROSS MUCH OF SOUTHEAST GEORGIA WHICH IS IN CLOSER PROXIMITY
TO THE FRONT AND THE DEEPER MOISTURE...WITH SOMEWHAT DRIER
CONDITIONS POSSIBLE FARTHER NORTH INTO PARTS OF SOUTHEAST SOUTH
CAROLINA.
TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH FRIDAY...THEN
COOLER/BELOW TEMPERATURES WILL OCCUR DURING THE REMAINDER OF THE
LONG TERM PERIOD AS A NORTHEAST FLOW DEVELOPS AS HIGH PRESSURE
BUILDS SOUTHWARD INTO THE REGION.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 12Z TUE.
EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS WITH A GREATER
THAN 30 PERCENT CONFIDENCE AT THIS TIME.
&&
.MARINE...
TODAY AND TONIGHT...HIGH PRESSURE WILL BUILD IN FROM THE NORTH
CAUSING WINDS TO SHIFT TO EASTERLY BUT REMAINING 15 KT OR LESS.
WINDS COULD BACK TO MORE NORTHEAST NEAR THE COAST LATE TONIGHT AS
A WEAK COASTAL TROUGH OF LOW PRESSURE TRIES TO DEVELOP. SIGNIFICANT WAVE
HEIGHTS WILL BE UP TO 3 FT WITHIN 20 NM AND UP TO 4 FT BEYOND 20
NM...DOMINATED BY A 8-9 SECOND E/SE SWELL...AT LEAST THROUGH
TODAY.
TUESDAY THROUGH SATURDAY...HIGH PRESSURE WILL BUILD OVER THE
REGION FROM THE NORTH THROUGH WEDNESDAY...MAINTAINING AN ONSHORE
FLOW OVER THE WATERS WITH WIND SPEEDS GENERALLY 15 KT OR LESS. THE
FLOW WILL BECOME MORE SOUTHERLY ON THURSDAY AHEAD OF AN APPROACHING
COLD FRONT...WHICH IS EXPECTED TO DROP ACROSS THE WATERS FRIDAY AND
FRIDAY NIGHT SHIFTING THE WINDS NORTHEAST IN ITS WAKE. A STRONG
NORTHEAST SURGE WILL THEN OCCUR FRIDAY NIGHT AND SATURDAY...LIKELY
RESULTING IN SMALL CRAFT ADVISORY CONDITIONS OVER PORTIONS OF THE
WATERS. SEAS WILL GENERALLY BE NO HIGHER THAN 2-4 FT...GREATEST OVER
THE OUTER GEORGIA WATERS...THROUGH FRIDAY BEFORE INCREASING A COUPLE
OF FEET SATURDAY AS THE STRONG NORTHEAST FLOW DEVELOPS AND THE FETCH
INCREASES.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
749 AM EDT MON SEP 9 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 536 AM EDT MON SEP 9 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MID LEVEL LOW OVER MT.
LOW IS WEAKENING/OPENING UP AND FINALLY MOVING E AFTER BEING OVER
THE PACIFIC NW DURING THE LAST FEW DAYS. AHEAD OF THIS FEATURE...
SHRA/TSRA OVER THE WRN DAKOTAS LAST EVENING HAVE ORGANIZED INTO A
WELL DEVELOPED MCS WHICH IS NOW MOVING ACROSS THE ERN DAKOTAS. PER
LATEST RUC/SPC MESOANALYSIS...40-50KT LOW-LEVEL JET IS ADVECTING
MUCAPE OF 3000J/KG INTO THE COMPLEX...HELPING TO MAINTAIN IT. MCS IS
MOVING AROUND A WEAKENING RIDGE WHICH REMAINS OVER THE CNTRL CONUS.
CLOSER TO HOME...SOME -SHRA...MOSTLY JUST SPRINKLES...HAVE PUSHED
ACROSS THE WRN AND SRN FCST AREA OVERNIGHT IN A GENERALLY WEAK
ISENTROPIC ASCENT REGIME. OVER THE LAST COUPLE OF HRS...SOUTHERLY
FLOW UP LAKE MICHIGAN HAS INCREASED ENOUGH TO BEGIN PUSHING HIGHER
DWPT MARINE LAYER AIR INTO THE ERN FCST AREA. WITH TEMPS IN THE
INTERIOR IN THE 40S/LWR 50S...MAY SEE SOME FOG/STRATUS DEVELOP THERE
IN THE NEXT COUPLE OF HRS.
INITIALLY...WILL CARRY ISOLD/SCT SHRA ACROSS THE FCST AREA FOR THE
NEXT SEVERAL HRS IN ONGOING MODEST WAA/ISENTROPIC ASCENT. THEN...
SHORT TERM FCST WILL REVOLVE AROUND PROGRESS OF THE SYSTEM OVER MT
AND MORE IMPORTANTLY THE MCS OVER THE DAKOTAS. AS ALWAYS...PINNING
DOWN CONVECTION EVEN IN THE SHORT TERM IS A CHALLENGE. TODAYS FCST
IS ESPECIALLY CHALLENGING GIVEN THE WELL-DEVELOPED MCS NOW OVER THE
ERN DAKOTAS AS IT SEEMS QUITE LIKELY THAT AN MCV WILL SPIN UP AND
MAY BECOME THE MAIN FEATURE TO KEY ON FOR THE PCPN FCST HERE. TRIED
TO INCORPORATE THE IDEA OF THE MCS HOLDING TOGETHER TO SOME EXTENT.
AS IT LIFTS ENE...MAY SEE AN ARC OF SHRA/TSRA SWING ACROSS
ESPECIALLY NW UPPER MI LATER THIS MORNING IN ZONE OF ENHANCED
WAA/ISENTROPIC ASCENT. WHAT TRANSPIRES AFTERWARDS IS UNCERTAIN. IF
MCV TRACKS N OF THE AREA...THE MAIN CLUSTER OF SHRA/TSRA WILL PASS
MOSTLY N OF UPPER MI TODAY WITH TAIL OF WAVE POSSIBLY GENERATING A
BAND OF SVR STORMS LATE AFTN/EVENING AS MLCAPE UPWARDS OF 2000J/KG
BUILDS NE INTO UPPER MI IN THE PRESENCE OF 40-50KT DEEP LAYER SHEAR.
IF MCV PASSES ACROSS UPPER MI...THEN MOST AREAS WILL SEE A FEW HRS
OF SHRA/TSRA THIS AFTN...AND MAIN SVR THREAT COULD BE SHUNTED S FOR
THE LATE AFTN/EVENING. BASED ON RADAR TRENDS...IT APPEARS THE FORMER
IDEA MAY BE THE MORE LIKELY SCENARIO. DEPENDING ON HOW FAR N WARM
SECTOR CAPPED AIR MASS ADVECTS TODAY...SRN FCST AREA MAY SEE
LITTLE/NO CONVECTION AFTER INITIAL POSSIBLE SHRA/TSRA IN
AFORMENTIONED ZONE OF ENHANCED WAA/ISENTROPIC ASCENT PASSES LATER
THIS MORNING.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 412 AM EDT MON SEP 9 2013
TUESDAY MORNING WILL MARK THE BEGINNING OF A COOLER AND GENERALLY
DRIER TREND THAT WILL REMAIN THROUGH THE REST OF THE FCST PERIOD.
850MB TEMPS AT DAYBREAK TUESDAY SHOULD BE 14-19C...WHICH WILL NOT BE
SEEN AGAIN UNTIL NEXT TUESDAY AT THE EARLIEST.
THE SFC LOW WILL BE EXITING/SLOWLY SINKING TO OUR SE ON TUESDAY...AS
A RIDGE BRIEFLY SLIDES IN. WHILE THERE WILL BE A PERIOD OF DRY
WEATHER...IT WILL BE SHORT LIVED...AS A SERIES OF SHORTWAVES WILL
KEEP IMPACTING THE UPPER GREAT LAKES THROUGH THE DAY THURSDAY.
HIGH PRESSURE WILL BUILD IN AT THE SFC AND ALOFT THURSDAY NIGHT. THE
COLDEST AIR WILL LIKELY BE OVERHEAD THURSDAY NIGHT INTO FRIDAY
MORNING...WITH BOTH THE GFS AND ECMWF INDICATING 850MB TEMPS BETWEEN
0 AND -2C FROM 00Z-12Z FRIDAY ON NNW-NE WINDS OFF LAKE SUPERIOR.
WHILE THERE WILL BE SOME DRYING THURSDAY NIGHT WITH HIGH PRESSURE
ROLLING IN...DIMINISHING 15-20KTS WINDS OFF LAKE SUPERIOR WILL HELP
KEEP LOW LEVEL MOISTURE STUCK ACROSS N UPPER MI INTO FRIDAY MORNING
AS A STRENGTHENING INVERSION TAKES HOLD. FRIDAY MORNING TEMPERATURES
ARE TRICKY. THE 09/00Z RUN OF THE GFS WARMED 850MB TEMPS 2C ON
AVERAGE...WHICH IS APPROX 3-4C WARMER THAN THE 09/12Z ECMWF.
AS THE SFC HIGH EXITS FRIDAY AFTERNOON/EVENING...SLIGHTLY WARMER AIR
WILL BE ABLE TO SWING IN ON W-SW WINDS. THERE WILL STILL BE THE
POTENTIAL FOR PATCHY FROST...BUT MOST LIKELY OVER THE INLAND E
LOCATIONS THAT ARE STILL UNDER THE LINGER INFLUENCE OF THE EXITING
HIGH. WHILE 80 DEGREE TEMPS WILL NOT RETURN...50 DEGREE READING ON
FRIDAY WILL RISE INTO THE MID 60S FOR THE UPCOMING WEEKEND. THE
WARMER TEMPERATURES WILL BE ACCOMPANIED BY A CHANCE OF SHOWERS TO
WRAP UP THE WEEKEND. WILL KEEP THE MENTION OF TS OUT FOR SUNDAY...AS
THE BEST POTENTIAL SHOULD REMAIN WELL TO OUR SW...CLOSER TO THE SFC
LOW ACROSS THE CENTRAL PLAINS WHERE MUCH WARMER AIR WILL RESIDE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 749 AM EDT MON SEP 9 2013
WARM/MOIST AIR SURGING N INTO THE UPPER GREAT LAKES WILL RESULT IN
GENERALLY MVFR CIGS THRU THE DAY AT KIWD/KCMX/KSAW. CONVECTIVE
COMPLEX RACING ACROSS MN SHOULD HOLD TOGETHER SUFFICIENTLY TO BRING
2-3HRS OF SHRA/IFR CONDITIONS TO KIWD LATER THIS MORNING AND TO
KCMX/KSAW THIS AFTN. OCCURRENCE OF TS AT ANY OF THE TERMINALS IS
SOMEWHAT UNCERTAIN AS CONVECTION BEGINS TO OUTRUN INSTABILITY TO
SOME DEGREE. FOR NOW...INCLUDED VCTS. AFTER INITIAL SHRA COMPLEX
PASSES...POTENTIAL FOR ADDITIONAL CONVECTION WILL RETURN THIS
EVENING. CONDITIONS AT ALL TERMINALS SHOULD FALL TO IFR OR LOWER
TONIGHT...ESPECIALLY AS WINDS BECOME UPSLOPING AT EACH TERMINAL.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 AM EDT MON SEP 9 2013
LOW PRESSURE OVER SD WILL PUSH THE EXITING RIDGE ACROSS LAKE
SUPERIOR EASTWARD TODAY. FUNNELING NE WINDS WILL GUST TO 20-25KTS
OVER FAR W LAKE SUPERIOR THIS AFTERNOON AND EVENING. EXPECT THE LOW
TO CROSS S LAKE SUPERIOR OVERNIGHT...AND PUSH INTO FAR SE ONTARIO ON
TUESDAY. A BRIEF RIDGE WILL MOVE OVER LAKE SUPERIOR TUESDAY
AFTERNOON THROUGH TUESDAY NIGHT...OUT AHEAD OF A WEAK TROUGH
EXTENDING FROM NORTHERN ONTARIO DURING THE DAY WEDNESDAY. LARGE HIGH
PRESSURE OVER SOUTH CENTRAL CANADA WEDNESDAY NIGHT WILL SLOWLY SINK
ACROSS GREAT LAKES...WHERE IT WILL REMAIN FROM THURSDAY NIGHT
THROUGH FRIDAY NIGHT. NW WINDS WILL LIKELY GUST 20-30KTS LATE
WEDNESDAY NIGHT THROUGH LATE THURSDAY NIGHT AS HIGH PRESSURE SINKS
IN FROM THE NNW. OTHERWISE WITH HIGH PRESSURE OVERHEAD...LIGHT WINDS
LESS THAN 20KTS ARE EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...ROLFSON
MARINE...KF
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
637 AM CDT Mon Sep 9 2013
.UPDATE:
Issued at 552 AM CDT Mon Sep 9 2013
Did a quick update, a few isolated thunderstorms have developed
over Marion and Fayette counties in southern IL. Latest HRRR run
shows even more activity firing up this morning, but isolated in
nature that could affect more of the CWA. Will have to keep an eye
on radar this morning. For now just have mention in far eastern
counties through 14z.
Byrd
&&
.SHORT TERM: (Through Late This Afternoon)
Issued at 326 AM CDT Mon Sep 9 2013
Front to continue moving back north as a warm front this morning,
so the above normal weather to persist through the next several
days. However, there is some residual mid clouds from weak
shortwave that is sliding through the area early this morning. As
for chances of isolated showers with this shortwave, feel that
they will develop just south of forecast area today, so kept
forecast dry for now. Otherwise, these clouds should clear out
from northwest to southeast today. So with 850 temps aoa 22C over
the central plains, will see high temps in the 90s with the
warmest temps over northern MO, while southeast MO/southern IL to
be a bit slower in its warm up due to the lingering mid clouds.
Despite dewpts mixing out by this afternoon and lowering into the
low to mid 60s, heat index values in northeast MO/west central IL
will approach 100.
Byrd
.LONG TERM: (Tonight through Sunday)
Issued at 326 AM CDT Mon Sep 9 2013
Another very mild night tonight with lows only in the upper 60s
to mid 70s. Hot and humid weather to persist on Tuesday with highs
in the mid to upper 90s with lows Tuesday night in the upper 60s
to low 70s. With highs in the mid to upper 90s both today and
Tuesday, could be close to record highs for this time of year.
Wednesday to remain another above normal day, though a few degrees
cooler as cu pop up ahead of next frontal boundary. Models are a bit
slower with this front now, but should still see it move into the
forecast area Wednesday night. Still not a lot of pcpn expected with
this boundary, so just kept low chance pops for far northern
counties on Wednesday, then spread chance pops south across most of
forecast area Wednesday night.
Beyond that, front to slide south of forecast area during the day
Thursday with surface ridge building in. This will bring in cooler
and drier conditions for the rest of the forecast period. Highs will
be in the mid to upper 80s on Thursday, then drop into the mid 70s
to mid 80s for the remainder of the forecast period. Lows will be in
the 50s over the weekend.
Byrd
&&
.AVIATION: (For the 12z TAFs through 12z Tuesday Morning)
Issued at 626 AM CDT Mon Sep 9 2013
Spotty showers have developed from the mid cloud deck present
across the area. Have even seen some lightning strikes well east
of the TAFS sites in south central IL. This precipitation should
dissipate by 15z or so with the mid clouds also becoming more
scattered. I have mentioned VCSH in the KCOU and St. Louis area
TAFS given the very low coverage, otherwise VFR conditions and
southwest winds will prevail today and tonight.
Specifics for KSTL:
Isolated showers have been noted in the St. Louis area associated
with the mid cloud deck present. This precipitation should
dissipate by 15z or so as the mid clouds become more scattered. I
have mentioned VCSH in the TAF given the very low coverage,
otherwise VFR conditions and southwest winds will prevail today
and tonight.
Glass
&&
.CLIMATE:
ISSUED AT 306 PM CDT SAT SEP 7 2013
RECORD HIGHS:
SEPT 9 SEPT 10
STL 101/1925 98/1983
COU 99/1925 99/1938
UIN 100/1945 100/1933
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
607 AM CDT Mon Sep 9 2013
.UPDATE...
Issued at 603 AM CDT MON SEP 9 2013
As noted in the 352 am discussion below an accas field has quickly
formed over the eastern portion of the CWA with widely scattered
elevated convection now being detected by radar. Have updated the
zones/grids to reflect this. Activity is expected to be short-lived
and dissipate by late morning.
&&
.SHORT TERM...(Today through Tuesday)
Issued at 352 AM CDT MON SEP 9 2013
The unseasonably hot conditions will continue today with near record
heat in parts of northern and west central MO. While H8 and 925mb
temperatures are progged to be 1-2C lower than Sunday when triple
digit readings were reached in the KC Metro, mixing will be better
and deeper due to increasing southwest winds. The net effect will be
afternoon temperatures topping out in the middle to upper 90s. If
there is any silver lining to today`s heat it`s the expectation of
lower humidity levels due to this better mixing.
The large anticyclone aloft will be nearly overhead and with its hot
mid level temperatures will suppress most cloud clover let alone any
convective development. However, there is one caveat to this
scenario and it revolves around a weak surface trough extending from
near OMA southeast through central MO. Some of the very short range
models like the RAP and HRRR are hinting at some elevated convection
near this boundary +/- 2-3 hours centered around 12Z. While the
models have been overly generous with qpf the last couple days with
the boundaries that have migrated into the CWA the latest satellite
imagery shows patches of apparently mid clouds forming from far east
central KS to central MO. Will need to monitor radar/satellite for
any development as the current forecast is dry.
Tuesday: more of the same although temperatures look like they will
be a few degrees cooler as the pool of hot air shifts northward.
Nonetheless, temperatures will remain a good 10F above average.
Lacking any boundary and with nearly non-existent moisture under a
strong cap will go with zero PoPs.
Tuesday night: A cold front from southern NE through WI will sag
slowly southward and possibly reach far northwest MO by Wednesday
morning. Models are becoming more reluctant to generate qpf over the
CWA as any convection which forms during this period will likely be
post-frontal. Have confined PoPs to far northwest MO and left rest
of CWA dry.
.LONG TERM...(Wednesday through Sunday)
Issued at 352 AM CDT MON SEP 9 2013
A rather weak front is expected to sink into northern Missouri by
Wednesday morning, but with limited precipitation accompanying it.
A narrow corridor of low level moisture will stretch across southern
Nebraska eastward into central Illinois into Thursday. Depending on
cloud cover, temperatures may again climb into the lower or even
middle 90s Wednesday afternoon and while low, a few thunderstorms
may develop in the unstable airmass south of the boundary.
Slightly higher PoPs are focused Wednesday night into Thursday as
the low-level baroclinic zone shifts southward. However, the LLJ
will back through the night into NW Kansas and SW Nebraska likely
forcing higher precipitation chances well west of the local area.
A secondary cold front will sweep into the area Thursday night,
allowing cool and dry air to push southwest. Temperatures heading
into the weekend will find themselves near the seasonal normals in
the upper 70s to lower 80s. An upper low crossing the Rockies over
the weekend will allow winds to turn back southwesterly on Saturday,
before another front moves into the area Sunday/Monday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 603 AM CDT MON SEP 9 2013
VFR conditions with little if any cloud cover during the period.
Primary concerns will center on the expected increase in
southwesterly winds by mid morning. Winds will remain gusty through
the entire afternoon before diminishing quickly shortly before sunset.
&&
.FIRE WEATHER...
Issued at 352 AM CDT MON SEP 9 2013
There is an elevated fire danger threat this afternoon across
northern and west central MO as well as extreme east central KS. The
heat of the past several days has quickly dried out the native
grasses. This combined with drought conditions across the area plus
humidity levels between 25 and 30 percent and southwest winds gusting
to 20 to 25 mph will increase the risk of rapid fire growth which
could quickly burn out of control.
&&
.CLIMATE...
Issued at 352 AM CDT MON SEP 9 2013
Record or near record heat is expected Monday afternoon over parts of
northern and west central MO and extreme east central KS.
Sep 9 record high/year
St. Joseph 98/1955
Kansas City 99/1970
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
UPDATE...MJ
SHORT TERM...MJ
LONG TERM...Dux
AVIATION...MJ
FIRE WEATHER...MJ
CLIMATE...MJ
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
555 AM CDT Mon Sep 9 2013
.UPDATE:
Issued at 552 AM CDT Mon Sep 9 2013
Did a quick update, a few isolated thunderstorms have developed
over Marion and Fayette counties in southern IL. Latest HRRR run
shows even more activity firing up this morning, but isolated in
nature that could affect more of the CWA. Will have to keep an eye
on radar this morning. For now just have mention in far eastern
counties through 14z.
Byrd
&&
.SHORT TERM: (Through Late This Afternoon)
Issued at 326 AM CDT Mon Sep 9 2013
Front to continue moving back north as a warm front this morning,
so the above normal weather to persist through the next several
days. However, there is some residual mid clouds from weak
shortwave that is sliding through the area early this morning. As
for chances of isolated showers with this shortwave, feel that
they will develop just south of forecast area today, so kept
forecast dry for now. Otherwise, these clouds should clear out
from northwest to southeast today. So with 850 temps aoa 22C over
the central plains, will see high temps in the 90s with the
warmest temps over northern MO, while southeast MO/southern IL to
be a bit slower in its warm up due to the lingering mid clouds.
Despite dewpts mixing out by this afternoon and lowering into the
low to mid 60s, heat index values in northeast MO/west central IL
will approach 100.
Byrd
.LONG TERM: (Tonight through Sunday)
Issued at 326 AM CDT Mon Sep 9 2013
Another very mild night tonight with lows only in the upper 60s
to mid 70s. Hot and humid weather to persist on Tuesday with highs
in the mid to upper 90s with lows Tuesday night in the upper 60s
to low 70s. With highs in the mid to upper 90s both today and
Tuesday, could be close to record highs for this time of year.
Wednesday to remain another above normal day, though a few degrees
cooler as cu pop up ahead of next frontal boundary. Models are a bit
slower with this front now, but should still see it move into the
forecast area Wednesday night. Still not a lot of pcpn expected with
this boundary, so just kept low chance pops for far northern
counties on Wednesday, then spread chance pops south across most of
forecast area Wednesday night.
Beyond that, front to slide south of forecast area during the day
Thursday with surface ridge building in. This will bring in cooler
and drier conditions for the rest of the forecast period. Highs will
be in the mid to upper 80s on Thursday, then drop into the mid 70s
to mid 80s for the remainder of the forecast period. Lows will be in
the 50s over the weekend.
Byrd
&&
.AVIATION: (For the 06z TAFs through 06z Monday Night)
Issued at 1142 PM CDT Sun Sep 8 2013
Primary concern for the rest of the night remains the probability
of isolated-widely scattered showers and thunderstorms
redeveloping along and east of the Mississippi River. It looks
like the best chance has shifted mostly to south of the St. Louis
Metro area across parts of the eastern Ozarks and southwest
Illinois. It does not look like a particularly strong or organized
round of showers and storms, but the signals in the models aren`t
very strong so confidence is low. VFR flight conditions should
prevail outside of any precipitation, except in area river valleys
where intermittent MFR conditions in fog can be expected.
VFR flight conditions are expected to prevail on Monday. The wind
will be increasing from the southwest with potential for gusts to
around 20kits especially across parts of central and northern
Missouri as well as west central Illinois.
Specifics for KSTL:
Expect VFR flight conditions to prevail for the rest of the night
at Lambert. Isolated showers are still possible...but the best
chances for rain look to have moved south/southeast of the
terminal. Signals in the models for rain aren`t particularly well
defined, so confidence in timing and locations of the showers is
low. River valley fog can be expected west of the terminal, but
shouldn`t impact the runway complex.
VFR flight conditions are expected to continue to prevail on
Monday. The wind will be increasing from the southwest in the
morning...and this will likely cause a brief period of direct
crosswinds on the main runways. However, the wind should continue
veering past 210 degrees by mid-late morning.
Carney
&&
.CLIMATE:
ISSUED AT 306 PM CDT SAT SEP 7 2013
RECORD HIGHS:
SEPT 9 SEPT 10
STL 101/1925 98/1983
COU 99/1925 99/1938
UIN 100/1945 100/1933
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1005 AM EDT MON SEP 9 2013
.SYNOPSIS...
A WEAK FRONT WILL MOVE OFFSHORE THIS MORNING. HIGH PRESSURE WILL
BUILD IN FROM THE NORTH AND EAST THROUGH MIDWEEK. ANOTHER STRONGER
COLD FRONT WILL MOVE THROUGH THE AREA EARLY FRIDAY. COOL HIGH
PRESSURE WILL BE OVER THE AREA THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 945 AM MONDAY...ADDED 20/30 POPS S COAST INTO EARLY
MORNING...WITH CURRENT SCT SHOWER ACTIVITY JUST OFFSHORE AFFECTING
CAPE LOOKOUT VICINITY NEXT FEW HOURS. MINOR ADJUSTMENTS TO TEMPS AND
SKY COVER. WINDS HAVE SHIFTED TO NE ALL ZONES WITH PASSAGE OF
LEADING EDGE OF WEAK SFC FRONT...BUT NO SIGNIFICANT CAA SURGE BEHIND
IT. ONSHORE FLOW WILL KEEP NRN OBX MAX TEMPS BELOW 80 BUT STILL
EXPECT MID TO UPR 80S INLAND. MESO MODELS INDICATE ISOLATED SHOWERS
PSBL INLAND THIS AFTN BUT DRY CONDITIONS ALOFT EXPECTED TO LIMIT
DEVELOPMENT...SO KEPT DRY FCST.
/PREVIOUS DISCUSSION/
AS OF 645 AM MONDAY...COLD FRONT CONTINUES TO MAKE SLOW PROGRESS
INTO NORTHEASTERN NORTH CAROLINA AND SHOULD BE NEAR OR JUST SOUTH
OF OUR COAST BY 12Z TO 14Z THIS MORNING WITH WINDS BECOMING NE
THEN GRADUALLY E LATER IN THE DAY AS HIGH PRESSURE DRIFTS
OFFSHORE. SATELLITE IMAGERY SHOWING LOW CLOUDS BEHIND THE FRONT
OVER VIRGINIA BUT FEEL SKIES WILL BE PARTLY CLOUDY OVER OUR
REGION ALLOWING TEMPERATURES TO APPROACH FORECAST MAX TEMPS IN THE
MID TO UPPER 80S IN MOST AREAS. THE 3 KM HRRR AND 4 KM WRF STILL
SHOW SOME ISOLATED SHOWERS ALONG THE SEA BREEZE IN THE AFTERNOON
BUT WITH LARGE SCALE SUBSIDENCE AND STRONG NVA OVER EASTERN
NC...WILL CONTINUE TO LEAVE POPS OUT OF THE FORECAST FOR TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
AS OF 340 AM MONDAY...THE LOW-LEVEL FLOW TONIGHT WILL BECOME LIGHT
AND ONSHORE. THIS WILL INCREASE BOUNDARY LAYER MOISTURE AND THERE
WILL AGAIN BE A GOOD LIKELYHOOD OF SOME LOWER STRATUS AND FOG
TOWARD MORNING. MINIMUM TEMPERATURES WILL BE FAIRLY SIMILAR TO
THIS MORNING WITH LOWS IN THE 66 TO 72 RANGE IN MOST AREAS.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 330 AM MON...THE LONG TERM PERIOD WILL FEATURE DRY AND WARM
WEATHER THROUGH THURSDAY...FOLLOWED BY A STRONG COLD FRONTAL
PASSAGE AND INCREASING PRECIP CHANCES THURSDAY NIGHT INTO
FRIDAY...THEN MUCH DRIER AND COOLER WEATHER FOR NEXT WEEKEND.
TEMPS WILL EDGE ABOVE CLIMO DURING THE MID WEEK TIME PERIOD WHILE
CONDITIONS REMAIN DRY WITH WESTERN ATLANTIC RIDGE CONTINUING TO
DOMINATE THE AREA. DEWPOINTS WILL BE ON THE INCREASE AS WELL WITH
TEMPS EDGING UPWARDS DURING THE OVERNIGHT PERIOD...THOUGH LOWS WILL
REMAIN NEAR CLIMO FOR EARLY SEPTEMBER. MED/LONG RANGE MODELS
CONVERGING ON STRONG SHORTWAVE TROUGH/SFC COLD FRONT TO AFFECT THE
AREA BEGINNING THURSDAY NIGHT. SW FLOW WILL INC ON THUR WITH TEMPS
REACHING INTO THE LOW 90S WITH TD`S INTO THE LOW 70S. ANY PRECIP
WILL REMAIN WELL WEST OF THE AREA THUR AFTERNOON WITH UPPER SUPPORT
IN THE APPALACHIANS. MODELS HAVE COME IN JUST A BIT FASTER WITH
FRONTAL PASSAGE...DURING THE DAY FRIDAY...THOUGH LAST SEVERAL RUNS
OF ECMWF HAVE COME IN DRIER THAN THE GFS WITH BULK OF UPPER SUPPORT
SHUNTING NORTH OF NC THROUGH THE MID ATLANTIC REGION. HAVE EDGED
POPS DOWNWARD TO 30-40 PERCENT TO REFLECT THE POSSIBLE DRIER FRONTAL
PASSAGE...AND MAY HAVE TO DECREASE FURTHER IF THIS TREND CONTINUES.
STRONG COOL AND DRY HIGH PRES WILL BUILD INTO THE AREA FROM THE NW
NEXT WEEKEND WITH TEMPS EXPECTED BELOW CLIMO ALONG WITH MUCH LOWER
RELATIVE HUMIDITY VALS.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
SHORT TERM /TODAY AND TONIGHT/...
AS OF 650 AM MONDAY...OCCASIONAL STRATUS AND FOG HAS BEEN REPORTED
AT THE TAF SITES THIS MORNING WITH KPGV BRIEFLY DROPPING TO LIFR.
AS THE COLD FRONT APPROACHES FROM THE VA/NC BORDER...EXPECT BETTER
MIXING AND ANY STRATUS AND FOG TO GRADUALLY DISSIPATE BY 12Z TO
14Z. WILL LIKELY SEE SOME SCATTERED TO BROKEN CUMULUS THROUGH
EARLY AFTERNOON...THEN CLEARING SKIES. MODEL GUIDANCE AGAIN
INDICATES LOW STRATUS AND FOG AGAIN TONIGHT AND WILL TREND THE
FORECAST THAT WAY ONCE AGAIN.
LONG TERM /TUE THROUGH SAT/...
AS OF 330 AM MON...MAINLY VFR CONDITIONS THROUGH THE LONG TERM
PERIOD...WITH THE EXCEPTION OF LATE NIGHT/EARLY AM RADIATION FOG.
HIGH PRES WILL DOMINATE THROUGH THURSDAY...FOLLOWED BY A STRONG
COLD FRONT PUSHING THROUGH LATE THURSDAY NIGHT INTO FRIDAY. A
SMALL CHANCE OF PRECIP WILL ACCOMPANY THE FRONTAL PASSAGE. STRONG
DRY HIGH PRES WILL BUILD IN FOR NEXT WEEKEND.
&&
.MARINE...
SHORT TERM /TODAY AND TONIGHT/...
AS OF 945 AM MONDAY...INCREASED POPS TO 30% AND ADDED MENTION OF
ISOLD TO SCT SHOWERS FOR SRN WATERS INTO EARLY AFTN...PER NEAR TERM
DISCUSSION WITH ONGOING ACTIVITY NEAR CAPE LOOKOUT. NO SIGNIFICANT
CHANGES TO WINDS/SEAS...WEAK SFC FRONT HAS PUSHED S OF AREA AND CAA
SURGE WILL GENERALLY REMAIN 15 KT OR BELOW.
/PREVIOUS DISCUSSION/
AS OF 655 AM MONDAY...WINDS HAVE BECOME NE OVER THE FAR NORTHERN
WATERS AND SHOULD GRADUALLY VEER FROM SW/W AROUND TO N/NE OVER THE
NEXT 3 OR 4 HOURS OVER ALL WATERS AND SOUNDS. GIVEN SOME GUSTS
INTO THE HIGH TEENS OVER THE HAMPTON ROADS AREA OF VIRGINIA
FOLLOWING THE FRONTAL PASSAGE...HAVE BUMPED WINDS INTO THE 10 TO
15 KNOT RANGE OVER ALL WATERS AND WOULD NOT BE SURPRISED TO SEE A
FEW GUSTS APPROACHING 20 KNOTS THIS MORNING BEFORE SUBSIDING THIS
AFTERNOON AS THE HIGH MOVES OFFSHORE. SEAS SHOULD REMAIN IN THE 2
TO 4 FOOT RANGE. LOCAL NWPS MODEL SHOWS SEAS BUILDING TO AROUND 4
FEET OVER THE CENTRAL AND NORTHERN WATERS TONIGHT AS THE HIGH
MOVES OFFSHORE AND MORE SE SWELL ENERGY DEVELOPS.
LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 330 AM MON...WINDS WILL GRADUALLY VEER TO THE E AND SE TUE
INTO WED WITH SPEEDS 10 KT OR LESS AS THE SFC RIDGE EXTENDS OVER
AREA FROM E-NE. FLOW WILL INCREASE A BIT FROM THE SW LATE THU AHEAD
OF THE NEXT APPROACHING COLD FRONT. POTENTIAL FOR SCA CONDITIONS FRI
INTO THE WEEKEND AS STRONG HIGH PRES BUILDS IN FROM THE NW WITH COLD
AIR ADVECTION OVER THE WATERS AND TIGHTENING NE GRADIENT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...CTC
NEAR TERM...JBM/CTC
SHORT TERM...CTC
LONG TERM...TL
AVIATION...CTC/TL
MARINE...CTC/TL/JBM
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
655 AM EDT MON SEP 9 2013
.SYNOPSIS...
A WEAK FRONT WILL MOVE OFFSHORE THIS MORNING. HIGH PRESSURE WILL
BUILD IN FROM THE NORTH AND EAST THROUGH MIDWEEK. ANOTHER STRONGER
COLD FRONT WILL MOVE THROUGH THE AREA EARLY FRIDAY. COOL HIGH PRESSURE
WILL BE OVER THE AREA THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 645 AM MONDAY...COLD FRONT CONTINUES TO MAKE SLOW PROGRESS
INTO NORTHEASTERN NORTH CAROLINA AND SHOULD BE NEAR OR JUST SOUTH
OF OUR COAST BY 12Z TO 14Z THIS MORNING WITH WINDS BECOMING NE
THEN GRADUALLY E LATER IN THE DAY AS HIGH PRESSURE DRIFTS
OFFSHORE. SATELLITE IMAGERY SHOWING LOW CLOUDS BEHIND THE FRONT
OVER VIRGINIA BUT FEEL SKIES WILL BE PARTLY CLOUDY OVER OUR
REGION ALLOWING TEMPERATURES TO APPROACH FORECAST MAX TEMPS IN THE
MID TO UPPER 80S IN MOST AREAS. THE 3 KM HRRR AND 4 KM WRF STILL
SHOW SOME ISOLATED SHOWERS ALONG THE SEA BREEZE IN THE AFTERNOON
BUT WITH LARGE SCALE SUBSIDENCE AND STRONG NVA OVER EASTERN
NC...WILL CONTINUE TO LEAVE POPS OUT OF THE FORECAST FOR TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
AS OF 340 AM MONDAY...THE LOW-LEVEL FLOW TONIGHT WILL BECOME LIGHT
AND ONSHORE. THIS WILL INCREASE BOUNDARY LAYER MOISTURE AND THERE
WILL AGAIN BE A GOOD LIKELYHOOD OF SOME LOWER STRATUS AND FOG
TOWARD MORNING. MINIMUM TEMPERATURES WILL BE FAIRLY SIMILAR TO
THIS MORNING WITH LOWS IN THE 66 TO 72 RANGE IN MOST AREAS.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 330 AM MON...THE LONG TERM PERIOD WILL FEATURE DRY AND WARM
WEATHER THROUGH THURSDAY...FOLLOWED BY A STRONG COLD FRONTAL
PASSAGE AND INCREASING PRECIP CHANCES THURSDAY NIGHT INTO
FRIDAY...THEN MUCH DRIER AND COOLER WEATHER FOR NEXT WEEKEND.
TEMPS WILL EDGE ABOVE CLIMO DURING THE MID WEEK TIME PERIOD WHILE
CONDITIONS REMAIN DRY WITH WESTERN ATLANTIC RIDGE CONTINUING TO
DOMINATE THE AREA. DEWPOINTS WILL BE ON THE INCREASE AS WELL WITH
TEMPS EDGING UPWARDS DURING THE OVERNIGHT PERIOD...THOUGH LOWS WILL
REMAIN NEAR CLIMO FOR EARLY SEPTEMBER. MED/LONG RANGE MODELS
CONVERGING ON STRONG SHORTWAVE TROUGH/SFC COLD FRONT TO AFFECT THE
AREA BEGINNING THURSDAY NIGHT. SW FLOW WILL INC ON THUR WITH TEMPS
REACHING INTO THE LOW 90S WITH TD`S INTO THE LOW 70S. ANY PRECIP
WILL REMAIN WELL WEST OF THE AREA THUR AFTERNOON WITH UPPER SUPPORT
IN THE APPALACHIANS. MODELS HAVE COME IN JUST A BIT FASTER WITH
FRONTAL PASSAGE...DURING THE DAY FRIDAY...THOUGH LAST SEVERAL RUNS
OF ECMWF HAVE COME IN DRIER THAN THE GFS WITH BULK OF UPPER SUPPORT
SHUNTING NORTH OF NC THROUGH THE MID ATLANTIC REGION. HAVE EDGED
POPS DOWNWARD TO 30-40 PERCENT TO REFLECT THE POSSIBLE DRIER FRONTAL
PASSAGE...AND MAY HAVE TO DECREASE FURTHER IF THIS TREND CONTINUES.
STRONG COOL AND DRY HIGH PRES WILL BUILD INTO THE AREA FROM THE NW
NEXT WEEKEND WITH TEMPS EXPECTED BELOW CLIMO ALONG WITH MUCH LOWER
RELATIVE HUMIDITY VALS.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
SHORT TERM /TODAY AND TONIGHT/...
AS OF 650 AM MONDAY...OCCASIONAL STRATUS AND FOG HAS BEEN REPORTED
AT THE TAF SITES THIS MORNING WITH KPGV BRIEFLY DROPPING TO LIFR.
AS THE COLD FRONT APPROACHES FROM THE VA/NC BORDER...EXPECT BETTER
MIXING AND ANY STRATUS AND FOG TO GRADUALLY DISSIPATE BY 12Z TO
14Z. WILL LIKELY SEE SOME SCATTERED TO BROKEN CUMULUS THROUGH
EARLY AFTERNOON...THEN CLEARING SKIES. MODEL GUIDANCE AGAIN
INDICATES LOW STRATUS AND FOG AGAIN TONIGHT AND WILL TREND THE
FORECAST THAT WAY ONCE AGAIN.
LONG TERM /TUE THROUGH SAT/...
AS OF 330 AM MON...MAINLY VFR CONDITIONS THROUGH THE LONG TERM
PERIOD...WITH THE EXCEPTION OF LATE NIGHT/EARLY AM RADIATION FOG.
HIGH PRES WILL DOMINATE THROUGH THURSDAY...FOLLOWED BY A STRONG
COLD FRONT PUSHING THROUGH LATE THURSDAY NIGHT INTO FRIDAY. A
SMALL CHANCE OF PRECIP WILL ACCOMPANY THE FRONTAL PASSAGE. STRONG
DRY HIGH PRES WILL BUILD IN FOR NEXT WEEKEND.
&&
.MARINE...
SHORT TERM /TODAY AND TONIGHT/...
AS OF 655 AM MONDAY...WINDS HAVE BECOME NE OVER THE FAR NORTHERN
WATERS AND SHOULD GRADUALLY VEER FROM SW/W AROUND TO N/NE OVER THE
NEXT 3 OR 4 HOURS OVER ALL WATERS AND SOUNDS. GIVEN SOME GUSTS
INTO THE HIGH TEENS OVER THE HAMPTON ROADS AREA OF VIRGINIA
FOLLOWING THE FRONTAL PASSAGE...HAVE BUMPED WINDS INTO THE 10 TO
15 KNOT RANGE OVER ALL WATERS AND WOULD NOT BE SURPRISED TO SEE A
FEW GUSTS APPROACHING 20 KNOTS THIS MORNING BEFORE SUBSIDING THIS
AFTERNOON AS THE HIGH MOVES OFFSHORE. SEAS SHOULD REMAIN IN THE 2
TO 4 FOOT RANGE. LOCAL NWPS MODEL SHOWS SEAS BUILDING TO AROUND 4
FEET OVER THE CENTRAL AND NORTHERN WATERS TONIGHT AS THE HIGH
MOVES OFFSHORE AND MORE SE SWELL ENERGY DEVELOPS.
LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 330 AM MON...WINDS WILL GRADUALLY VEER TO THE E AND SE TUE
INTO WED WITH SPEEDS 10 KT OR LESS AS THE SFC RIDGE EXTENDS OVER
AREA FROM E-NE. FLOW WILL INCREASE A BIT FROM THE SW LATE THU AHEAD
OF THE NEXT APPROACHING COLD FRONT. POTENTIAL FOR SCA CONDITIONS FRI
INTO THE WEEKEND AS STRONG HIGH PRES BUILDS IN FROM THE NW WITH COLD
AIR ADVECTION OVER THE WATERS AND TIGHTENING NE GRADIENT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...CTC
NEAR TERM...CTC
SHORT TERM...CTC
LONG TERM...TL
AVIATION...CTC/TL
MARINE...CTC/TL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1017 AM CDT MON SEP 9 2013
.UPDATE...
ISSUED AT 1017 AM CDT MON SEP 9 2013
UPDATE THIS MORNING DEALT MAINLY WITH ADJUSTING CLOUDS AND POPS TO
CURRENT RADAR AND SATELLITE IMAGERY. CLEARING OUT ACROSS THE
SOUTHWEST...BUT SHOWERS CONTINUE OVER THE NORTH CENTRAL ON THE
BACK SIDE OF THE SURFACE LOW OVER SOUTHEAST NORTH DAKOTA.
UPDATE ISSUED AT 644 AM CDT MON SEP 9 2013
THE LATEST RADAR TRENDS AND 3KM HRRR INDICATE DECREASING
PRECIPITATION INTENSITY ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
EVEN THOUGH COPIOUS AMOUNTS OF MOISTURE ARE OVER THE AREA...THE
ATMOSPHERE IS PRETTY WELL WORKED OVER FOR ANY STORMS TO GROW
UPSCALE THIS MORNING. AS A RESULT...DECIDED TO CANCEL THE FLASH
FLOOD WATCH ACROSS THE ENTIRE CWA THIS MORNING.
AN UPPER LEVEL LOW CURRENTLY SITUATED OVER NORTH CENTRAL MONTANA
IS FORECAST TO PIVOT INTO NORTHWESTERN NORTH DAKOTA LATER THIS
AFTERNOON. THIS COMBINED WITH INCREASING UPPER LEVEL DYNAMICS MAY
ALLOW THUNDERSTORMS TO DEVELOP AND BECOME SEVERE...MAINLY NORTH
OF I-94 LATER THIS AFTERNOON AND EVENING. THE DAY 1 SPC OUTLOOK
HAS NORTHERN NORTH DAKOTA IN A "SEE TEXT" CATEGORY AND A 5% CHANCE
OF DAMAGING WINDS AND HAIL. AS A RESULT...HIGHLIGHTED THIS THREAT
IN THE HWO. HOWEVER...KEPT IT OUT OF THE ZONES DUE TO ITS LOW
PROBABILITY.
THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 452 AM CDT MON SEP 9 2013
THE SEVERE THREAT HAS ENDED ACROSS THE JAMES RIVER BASIN. AS A
RESULT...CANCELLED THE SEVERE THUNDERSTORM WATCH FOR THE AFFECTED
AREAS. OTHERWISE...ONLY MODIFIED THE REMAINING WEATHER ELEMENTS
BASED ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT MON SEP 9 2013
IN THE NEAR TERM...THE SEVERE WEATHER THREAT IS LIKELY OVER AS THE
BOW ECHO HAS PUSHED EAST OF THE FORECAST AREA. HEAVY RAIN THREAT
WILL PERSIST...MAINLY IN THE JAMES RIVER VALLEY THIS MORNING. SEE
HYDRO DISCUSSION BELOW FOR DETAILS. MUCH OF THE FORECAST AREA IS
MENTIONED IN THE SEE TEXT AREA OF THE SPC DAY 1 OUTLOOK. ISOLD
LARGE HAIL/WIND GUSTS NOT OUT OF THE QUESTION THIS
AFTERNOON/EVENING. WITH THE 500MB COLD POOL MOVING INTO THE NORTH
THIS AFTERNOON...WILL ALSO HAVE TO MONITOR FOR POTENTIAL
FUNNELS/BRIEF NON-SUPERCELL TORNADOES.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 350 AM CDT MON SEP 9 2013
QUIET WEATHER WILL CONTINUE FOR MUCH OF THE LONG TERM PERIOD. THE
MAIN WINDOW FOR THUNDERSTORM ACTIVITY WILL BE FRIDAY
NIGHT/SATURDAY. OTHERWISE...EXPECT MILDER TEMPS WITH HIGHS
GENERALLY IN THE 70S TO LOWER 80S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1017 AM CDT MON SEP 9 2013
AREAS MVFR CEILINGS AND VISIBILITIES OVER CENTRAL NORTH DAKOTA
THIS MORNING FROM KMOT AND KBIS EAST THROUGH KJMS. EXPECT THESE TO
CLEAR SLOWLY THROUGH EARLY AFTERNOON. LOWER CEILINGS AND
VISIBILITIES HAVE CLEARED AT KISN AND KDIK. AREAS MVFR CEILINGS
AND VISIBILITIES IN SHOWERS AND SCATTERED THUNDERSTORMS THIS
AFTERNOON FROM KISN TO KMOT AS UPPER LEVEL LOW TRACKS EAST ACROSS
THIS AREA. EXPECT VFR CONDITIONS THIS EVENING THROUGH 18Z TUESDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...RK
LONG TERM...RK
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
644 AM CDT MON SEP 9 2013
.UPDATE...
ISSUED AT 644 AM CDT MON SEP 9 2013
THE LATEST RADAR TRENDS AND 3KM HRRR INDICATE DECREASING
PRECIPITATION INTENSITY ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
EVEN THOUGH COPIOUS AMOUNTS OF MOISTURE ARE OVER THE AREA...THE
ATMOSPHERE IS PRETTY WELL WORKED OVER FOR ANY STORMS TO GROW
UPSCALE THIS MORNING. AS A RESULT...DECIDED TO CANCEL THE FLASH
FLOOD WATCH ACROSS THE ENTIRE CWA THIS MORNING.
AN UPPER LEVEL LOW CURRENTLY SITUATED OVER NORTH CENTRAL MONTANA
IS FORECAST TO PIVOT INTO NORTHWESTERN NORTH DAKOTA LATER THIS
AFTERNOON. THIS COMBINED WITH INCREASING UPPER LEVEL DYNAMICS MAY
ALLOW THUNDERSTORMS TO DEVELOP AND BECOME SEVERE...MAINLY NORTH
OF I-94 LATER THIS AFTERNOON AND EVENING. THE DAY 1 SPC OUTLOOK
HAS NORTHERN NORTH DAKOTA IN A "SEE TEXT" CATEGORY AND A 5% CHANCE
OF DAMAGING WINDS AND HAIL. AS A RESULT...HIGHLIGHTED THIS THREAT
IN THE HWO. HOWEVER...KEPT IT OUT OF THE ZONES DUE TO ITS LOW
PROBABILITY.
THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 452 AM CDT MON SEP 9 2013
THE SEVERE THREAT HAS ENDED ACROSS THE JAMES RIVER BASIN. AS A
RESULT...CANCELLED THE SEVERE THUNDERSTORM WATCH FOR THE AFFECTED
AREAS. OTHERWISE...ONLY MODIFIED THE REMAINING WEATHER ELEMENTS
BASED ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT MON SEP 9 2013
IN THE NEAR TERM...THE SEVERE WEATHER THREAT IS LIKELY OVER AS THE
BOW ECHO HAS PUSHED EAST OF THE FORECAST AREA. HEAVY RAIN THREAT
WILL PERSIST...MAINLY IN THE JAMES RIVER VALLEY THIS MORNING. SEE
HYDRO DISCUSSION BELOW FOR DETAILS. MUCH OF THE FORECAST AREA IS
MENTIONED IN THE SEE TEXT AREA OF THE SPC DAY 1 OUTLOOK. ISOLD
LARGE HAIL/WIND GUSTS NOT OUT OF THE QUESTION THIS
AFTERNOON/EVENING. WITH THE 500MB COLD POOL MOVING INTO THE NORTH
THIS AFTERNOON...WILL ALSO HAVE TO MONITOR FOR POTENTIAL
FUNNELS/BRIEF NON-SUPERCELL TORNADOES.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 350 AM CDT MON SEP 9 2013
QUIET WEATHER WILL CONTINUE FOR MUCH OF THE LONG TERM PERIOD. THE
MAIN WINDOW FOR THUNDERSTORM ACTIVITY WILL BE FRIDAY
NIGHT/SATURDAY. OTHERWISE...EXPECT MILDER TEMPS WITH HIGHS
GENERALLY IN THE 70S TO LOWER 80S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 644 AM CDT MON SEP 9 2013
SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE AT ALL TERMINALS EARLY
THIS MORNING...ALONG WITH AREAS OF LIFR-VLIFR CIGS. CIGS ARE
FORECAST TO SCATTER OUT/LIFT 14-17Z...BUT MAY SEE SOME LOWER STRATUS
LINGER AT KJMS INTO EARLY THIS AFTERNOON. INCREASING AFTERNOON
CLOUDS 20-21Z THROUGH 02-04Z THIS EVENING MOST LOCATIONS...WITH
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS REDEVELOPING MAINLY AT
KISN-KMOT-KJMS. HIGH LOW LEVEL MOISTURE FROM RECENT RAINS COUPLED
WITH PARTIALLY CLEARING SKIES AND DECREASING WINDS MAY RESULT IN
FOG/STRATUS DEVELOPMENT LATER MONDAY NIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...RK
LONG TERM...RK
AVIATION...NH
AREA FORECAST DISCUSSION...UPDATED
NWS CLEVELAND OH
916 AM EDT MON SEP 9 2013
.SYNOPSIS...
AN AREA OF HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES
WILL MOVE OFF THE NEW ENGLAND COAST TODAY. THIS WILL ALLOW A WARM
FRONT TO LIFT NORTHEAST ACROSS THE LOCAL AREA. AN AREA OF LOW
PRESSURE WILL PASS WELL TO THE NORTH ON WEDNESDAY AND DRAG A COLD
FRONT ACROSS THE REGION ON WEDNESDAY NIGHT. HIGH PRESSURE WILL
RETURN FOR THE END OF THE WORKWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
TWEAKED TEMPS UP A LITTLE IN THE EAST...OTHERWISE FORECAST LOOKS
GOOD.
ORIGINAL...QUITE A BIT OF SHOWER AND THUNDERSTORM ACTIVITY OVER SW LOWER
MICHIGAN. THIS ACTIVITY HAS FORMED ALONG A WARM FRONT THAT WILL
LIFT NE ACROSS THE LOCAL AREA TODAY. ALL OF THE NEW
GUIDANCE...INCLUDING THE HRRR AND CONVECTIVE SREF SHOW AT LEAST
SCATTERED PRECIP. HAVE BUMPED PRECIP CHANCES UP ALL AREAS TO
AROUND 40 PERCENT. MAY EVENTUALLY HAVE TO BUMP IT EVER FURTHER
DEPENDING ON WHAT THE ACTIVITY OVER MI DOES. DEWPOINTS ARE ALREADY ON
THE WAY UP AND EXPECTING MID 60S BY EARLY EVENING. THERE SHOULD
BE A LOT OF CLOUDINESS TODAY BUT TEMPS WILL STILL MAKE THE 80S
OVER ALL BUT THE EASTERN END OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
THE WARM FRONT WILL MOVE NORTH OF LAKE ERIE THIS EVENING AND THAT
SHOULD END THE THREAT FOR ADDITIONAL PRECIP. WILL START THE
TONIGHT PERIOD OUT WITH SMALL POPS...ESPECIALLY ACROSS NW PA. THE
REMAINDER OF THE NIGHT AND TUESDAY SHOULD BE DRY. MODELS STILL
PUSHING 850 MB TEMPS TO PLUS 20 OR WARMER ON TUESDAY. NEW GUIDANCE
IS A TAD COOLER WITH HIGHS BUT HAVE NOT MADE ANY SIGNIFICANT
CHANGES. MUCH OF THE AREA SHOULD REACH THE 90 DEGREE MARK. THE
WARM AND HUMID AIRMASS WILL REMAIN IN PLACE ON WEDNESDAY AS WELL.
THERE SHOULD BE MORE CLOUDS AND INCREASING CHANCES FOR PRECIP.
THIS WILL HOLD TEMPS BACK A LITTLE. IT APPEARS THAT THE BEST
CHANCES FOR CONVECTION DURING THE PERIOD WILL COME WEDNESDAY
EVENING AND NIGHT AS THE COLD FRONT FINALLY ARRIVES. HAVE GIVEN
MUCH OF THE AREA LIKELY POPS. THERE WILL BE A DISTINCT AIRMASS
CHANGE BEHIND THE FRONT. STRONG COLD AIR ADVECTION IS EXPECTED
BEHIND THE FRONT ON THURSDAY. THE MODELS TRY TO DRY THINGS OUT
QUICKLY BUT SUSPECT THAT THIS IS TOO FAST. WILL LIKELY SEE A FAIR
AMOUNT OF CLOUDINESS AND PERHAPS A FEW SHOWERS DOWN WIND OF THE
LAKE. AFTER TUESDAY HAVE USED A BLEND OF GUIDANCE TEMPS.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
TROUGH ALOFT FRIDAY WITH A VERY COOL AIRMASS. STILL GOOD CONSENSUS
THAT H8 TEMPS WILL BE BETWEEN +2C AND +5C. WILL KEEP THE HIGHS IN
THE 60S BOTH FRIDAY AND SATURDAY...WITH EVEN SOME UPPER 50S ACROSS
NW PA ON FRIDAY. FAIRLY CLOUDY TO START FRIDAY WITH ADDITIONAL LAKE
CLOUDS...BUT BY LATE AFTERNOON HIGH PRESSURE FROM THE CENTRAL LAKES
REALLY BEGINS TO BUILD IN. WILL ALSO KEEP SOME LOW PRECIP CHANCES
FOR LAKE EFFECT RAIN SHOWERS. SIGNIFICANT DRYING AND RIDGING BEGIN
TO WORK IN FOR SATURDAY...SO PRECIP SHOULD NOT BE A PROBLEM. NIGH
LOWS WILL BE COOL FOR SURE...BUT CLOUD COVER WILL BE THE DETERMINING
FACTOR ON HOW COOL. TEMPERATURE RECOVERY BEGINS SUNDAY AS THE HIGH
SHIFTS EAST AND WE GET RETURN FLOW. THE NEXT FRONTAL SYSTEM WILL BE
ACROSS THE NORTHERN AND CENTRAL LAKES COME SUNDAY.
&&
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE AND DRY AIRMASS JUST TO OUR NORTHEAST. TO OUR
SOUTHWEST THERE IS A MORE HUMID AIRMASS AND A DEVELOPING WARM
FRONT. SHOWERS AND A FEW TS HAVE DEVELOPED AND PROPAGATED ACROSS
SOUTHERN LOWER MI AHEAD OF THE WARM FRONT...HEADING TOWARD TOL.
HAVE INCLUDED A VCTS FOR TOL...WITH ONLY LIMITED CLOUD-GROUND
LIGHTNING POSSIBLE AND A WEAKENING TREND ON RADAR MOSAIC. MVFR
CONDITIONS IN THE -RA LIKELY THOUGH. NOT EXPECTING THIS AREA OF
RAIN TO MAKE IT TOO MUCH FURTHER SE...BUT INSTEAD NEW SCATTERED
DEVELOPMENT POSSIBLE ALONG THAT WARM FRONT THIS AFTERNOON. WITH
CHANCES STILL AROUND 30 PERCENT OR SO...HAVE GONE WITH A VCSH
MENTION. THUNDER IS POSSIBLE...BUT HARD TO PINPOINT JUST YET.
WINDS WILL COME AROUND FROM THE ESE TO THE SOUTH WITH THE PASSAGE
OF THE FRONT. RIDGE REALLY BUILDS IN MONDAY EVENING AND PRECIP
CHANCES ARE EXPECTED TO BE OVER. VARIABLY CLOUDY WITH MID/HIGH
CLOUDS OVERNIGHT. SOUTH WIND STAYS UP AT 10 OR 12 KNOTS.
OUTLOOK...NON VFR WITH POSSIBLE SHOWERS/THUNDERSTORMS WEDNESDAY
THROUGH THURSDAY. MAY HAVE SOME NON VFR CEILINGS ACROSS THE
SNOWBELT THURSDAY AND FRIDAY.
&&
.MARINE...
SOUTHERLY FLOW TODAY AND A RELATIVELY NICE DAY ON THE LAKE. THERE
MAY BE A SHOWER OR THUNDERSTORM TODAY AS A WARM FRONT PUSHES
NORTHEAST ACROSS THE LAKE. FLOW COMES AROUND TO THE SOUTHWEST
TUESDAY AND PICKS UP ENOUGH THAT A SMALL CRAFT ADVISORY MAY BE
NEEDED ALONG THE EAST HALF/END. WINDS BEGIN TO DECREASE TUESDAY
NIGHT INTO WEDNESDAY AS A WEAKENING COLD FRONT BEGINS TO SINK SOUTH
ACROSS THE CENTRAL LAKES. WINDS SHIFT TO THE NORTHWEST BY THURSDAY
MORNING. SOME OF THE BETTER COLD AIR ADVECTION IS DELAYED UNTIL
FRIDAY. AT THAT POINT WINDS WILL PICK UP AND SMALL CRAFT CONDITIONS
WILL BE LIKELY. A MUCH COOLER AIRMASS WILL BRING LAKE EFFECT RAIN
SHOWERS TOO.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...DJB/KUBINA
SHORT TERM...KUBINA
LONG TERM...OUDEMAN
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
729 AM EDT MON SEP 9 2013
.SYNOPSIS...
AN AREA OF HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES
WILL MOVE OFF THE NEW ENGLAND COAST TODAY. THIS WILL ALLOW A WARM
FRONT TO LIFT NORTHEAST ACROSS THE LOCAL AREA. AN AREA OF LOW
PRESSURE WILL PASS WELL TO THE NORTH ON WEDNESDAY AND DRAG A COLD
FRONT ACROSS THE REGION ON WEDNESDAY NIGHT. HIGH PRESSURE WILL
RETURN FOR THE END OF THE WORKWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HAVE FINE TUNED PRECIP CHANCES THE NEXT FEW HOURS BASED ON RADAR
TRENDS. HAVE GONE WITH LIKELY POPS FOR A COUPLE OF COUNTIES IN NW
OH. THE PRECIP APPROACHING FROM THE WNW CONTINUES TO WEAKEN AND
VERY LITTLE LIGHTNING LEFT. THIS FIRST WAVE OF PRECIP SHOULD
DISSIPATE BEFORE GETTING TOO FAR INTO THE AREA. NEW DEVELOPMENT IS
LIKELY LATER THIS MORNING AS THE WARM FRONT APPROACHES FROM THE
SW.
ORIGINAL...QUITE A BIT OF SHOWER AND THUNDERSTORM ACTIVITY OVER SW LOWER
MICHIGAN. THIS ACTIVITY HAS FORMED ALONG A WARM FRONT THAT WILL
LIFT NE ACROSS THE LOCAL AREA TODAY. ALL OF THE NEW
GUIDANCE...INCLUDING THE HRRR AND CONVECTIVE SREF SHOW AT LEAST
SCATTERED PRECIP. HAVE BUMPED PRECIP CHANCES UP ALL AREAS TO
AROUND 40 PERCENT. MAY EVENTUALLY HAVE TO BUMP IT EVER FURTHER
DEPENDING ON WHAT THE ACTIVITY OVER MI DOES. DEWPOINTS ARE ALREADY ON
THE WAY UP AND EXPECTING MID 60S BY EARLY EVENING. THERE SHOULD
BE A LOT OF CLOUDINESS TODAY BUT TEMPS WILL STILL MAKE THE 80S
OVER ALL BUT THE EASTERN END OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
THE WARM FRONT WILL MOVE NORTH OF LAKE ERIE THIS EVENING AND THAT
SHOULD END THE THREAT FOR ADDITIONAL PRECIP. WILL START THE
TONIGHT PERIOD OUT WITH SMALL POPS...ESPECIALLY ACROSS NW PA. THE
REMAINDER OF THE NIGHT AND TUESDAY SHOULD BE DRY. MODELS STILL
PUSHING 850 MB TEMPS TO PLUS 20 OR WARMER ON TUESDAY. NEW GUIDANCE
IS A TAD COOLER WITH HIGHS BUT HAVE NOT MADE ANY SIGNIFICANT
CHANGES. MUCH OF THE AREA SHOULD REACH THE 90 DEGREE MARK. THE
WARM AND HUMID AIRMASS WILL REMAIN IN PLACE ON WEDNESDAY AS WELL.
THERE SHOULD BE MORE CLOUDS AND INCREASING CHANCES FOR PRECIP.
THIS WILL HOLD TEMPS BACK A LITTLE. IT APPEARS THAT THE BEST
CHANCES FOR CONVECTION DURING THE PERIOD WILL COME WEDNESDAY
EVENING AND NIGHT AS THE COLD FRONT FINALLY ARRIVES. HAVE GIVEN
MUCH OF THE AREA LIKELY POPS. THERE WILL BE A DISTINCT AIRMASS
CHANGE BEHIND THE FRONT. STRONG COLD AIR ADVECTION IS EXPECTED
BEHIND THE FRONT ON THURSDAY. THE MODELS TRY TO DRY THINGS OUT
QUICKLY BUT SUSPECT THAT THIS IS TOO FAST. WILL LIKELY SEE A FAIR
AMOUNT OF CLOUDINESS AND PERHAPS A FEW SHOWERS DOWN WIND OF THE
LAKE. AFTER TUESDAY HAVE USED A BLEND OF GUIDANCE TEMPS.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
TROUGH ALOFT FRIDAY WITH A VERY COOL AIRMASS. STILL GOOD CONSENSUS
THAT H8 TEMPS WILL BE BETWEEN +2C AND +5C. WILL KEEP THE HIGHS IN
THE 60S BOTH FRIDAY AND SATURDAY...WITH EVEN SOME UPPER 50S ACROSS
NW PA ON FRIDAY. FAIRLY CLOUDY TO START FRIDAY WITH ADDITIONAL LAKE
CLOUDS...BUT BY LATE AFTERNOON HIGH PRESSURE FROM THE CENTRAL LAKES
REALLY BEGINS TO BUILD IN. WILL ALSO KEEP SOME LOW PRECIP CHANCES
FOR LAKE EFFECT RAIN SHOWERS. SIGNIFICANT DRYING AND RIDGING BEGIN
TO WORK IN FOR SATURDAY...SO PRECIP SHOULD NOT BE A PROBLEM. NIGH
LOWS WILL BE COOL FOR SURE...BUT CLOUD COVER WILL BE THE DETERMINING
FACTOR ON HOW COOL. TEMPERATURE RECOVERY BEGINS SUNDAY AS THE HIGH
SHIFTS EAST AND WE GET RETURN FLOW. THE NEXT FRONTAL SYSTEM WILL BE
ACROSS THE NORTHERN AND CENTRAL LAKES COME SUNDAY.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE AND DRY AIRMASS JUST TO OUR NORTHEAST. TO OUR
SOUTHWEST THERE IS A MORE HUMID AIRMASS AND A DEVELOPING WARM
FRONT. SHOWERS AND A FEW TS HAVE DEVELOPED AND PROPAGATED ACROSS
SOUTHERN LOWER MI AHEAD OF THE WARM FRONT...HEADING TOWARD TOL.
HAVE INCLUDED A VCTS FOR TOL...WITH ONLY LIMITED CLOUD-GROUND
LIGHTNING POSSIBLE AND A WEAKENING TREND ON RADAR MOSAIC. MVFR
CONDITIONS IN THE -RA LIKELY THOUGH. NOT EXPECTING THIS AREA OF
RAIN TO MAKE IT TOO MUCH FURTHER SE...BUT INSTEAD NEW SCATTERED
DEVELOPMENT POSSIBLE ALONG THAT WARM FRONT THIS AFTERNOON. WITH
CHANCES STILL AROUND 30 PERCENT OR SO...HAVE GONE WITH A VCSH
MENTION. THUNDER IS POSSIBLE...BUT HARD TO PINPOINT JUST YET.
WINDS WILL COME AROUND FROM THE ESE TO THE SOUTH WITH THE PASSAGE
OF THE FRONT. RIDGE REALLY BUILDS IN MONDAY EVENING AND PRECIP
CHANCES ARE EXPECTED TO BE OVER. VARIABLY CLOUDY WITH MID/HIGH
CLOUDS OVERNIGHT. SOUTH WIND STAYS UP AT 10 OR 12 KNOTS.
OUTLOOK...NON VFR WITH POSSIBLE SHOWERS/THUNDERSTORMS WEDNESDAY
THROUGH THURSDAY. MAY HAVE SOME NON VFR CEILINGS ACROSS THE
SNOWBELT THURSDAY AND FRIDAY.
&&
.MARINE...
SOUTHERLY FLOW TODAY AND A RELATIVELY NICE DAY ON THE LAKE. THERE
MAY BE A SHOWER OR THUNDERSTORM TODAY AS A WARM FRONT PUSHES
NORTHEAST ACROSS THE LAKE. FLOW COMES AROUND TO THE SOUTHWEST
TUESDAY AND PICKS UP ENOUGH THAT A SMALL CRAFT ADVISORY MAY BE
NEEDED ALONG THE EAST HALF/END. WINDS BEGIN TO DECREASE TUESDAY
NIGHT INTO WEDNESDAY AS A WEAKENING COLD FRONT BEGINS TO SINK SOUTH
ACROSS THE CENTRAL LAKES. WINDS SHIFT TO THE NORTHWEST BY THURSDAY
MORNING. SOME OF THE BETTER COLD AIR ADVECTION IS DELAYED UNTIL
FRIDAY. AT THAT POINT WINDS WILL PICK UP AND SMALL CRAFT CONDITIONS
WILL BE LIKELY. A MUCH COOLER AIRMASS WILL BRING LAKE EFFECT RAIN
SHOWERS TOO.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...OUDEMAN
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
622 AM EDT MON SEP 9 2013
.SYNOPSIS...
AN AREA OF HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES
WILL MOVE OFF THE NEW ENGLAND COAST TODAY. THIS WILL ALLOW A WARM
FRONT TO LIFT NORTHEAST ACROSS THE LOCAL AREA. AN AREA OF LOW
PRESSURE WILL PASS WELL TO THE NORTH ON WEDNESDAY AND DRAG A COLD
FRONT ACROSS THE REGION ON WEDNESDAY NIGHT. HIGH PRESSURE WILL
RETURN FOR THE END OF THE WORKWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HAVE FINE TUNED PRECIP CHANCES THE NEXT FEW HOURS BASED ON RADAR
TRENDS. HAVE GONE WITH LIKELY POPS FOR A COUPLE OF COUNTIES IN NW
OH. THE PRECIP APPROACHING FROM THE WNW CONTINUES TO WEAKEN AND
VERY LITTLE LIGHTNING LEFT. THIS FIRST WAVE OF PRECIP SHOULD
DISSIPATE BEFORE GETTING TOO FAR INTO THE AREA. NEW DEVELOPMENT IS
LIKELY LATER THIS MORNING AS THE WARM FRONT APPROACHES FROM THE
SW.
ORIGINAL...QUITE A BIT OF SHOWER AND THUNDERSTORM ACTIVITY OVER SW LOWER
MICHIGAN. THIS ACTIVITY HAS FORMED ALONG A WARM FRONT THAT WILL
LIFT NE ACROSS THE LOCAL AREA TODAY. ALL OF THE NEW
GUIDANCE...INCLUDING THE HRRR AND CONVECTIVE SREF SHOW AT LEAST
SCATTERED PRECIP. HAVE BUMPED PRECIP CHANCES UP ALL AREAS TO
AROUND 40 PERCENT. MAY EVENTUALLY HAVE TO BUMP IT EVER FURTHER
DEPENDING ON WHAT THE ACTIVITY OVER MI DOES. DEWPOINTS ARE ALREADY ON
THE WAY UP AND EXPECTING MID 60S BY EARLY EVENING. THERE SHOULD
BE A LOT OF CLOUDINESS TODAY BUT TEMPS WILL STILL MAKE THE 80S
OVER ALL BUT THE EASTERN END OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
THE WARM FRONT WILL MOVE NORTH OF LAKE ERIE THIS EVENING AND THAT
SHOULD END THE THREAT FOR ADDITIONAL PRECIP. WILL START THE
TONIGHT PERIOD OUT WITH SMALL POPS...ESPECIALLY ACROSS NW PA. THE
REMAINDER OF THE NIGHT AND TUESDAY SHOULD BE DRY. MODELS STILL
PUSHING 850 MB TEMPS TO PLUS 20 OR WARMER ON TUESDAY. NEW GUIDANCE
IS A TAD COOLER WITH HIGHS BUT HAVE NOT MADE ANY SIGNIFICANT
CHANGES. MUCH OF THE AREA SHOULD REACH THE 90 DEGREE MARK. THE
WARM AND HUMID AIRMASS WILL REMAIN IN PLACE ON WEDNESDAY AS WELL.
THERE SHOULD BE MORE CLOUDS AND INCREASING CHANCES FOR PRECIP.
THIS WILL HOLD TEMPS BACK A LITTLE. IT APPEARS THAT THE BEST
CHANCES FOR CONVECTION DURING THE PERIOD WILL COME WEDNESDAY
EVENING AND NIGHT AS THE COLD FRONT FINALLY ARRIVES. HAVE GIVEN
MUCH OF THE AREA LIKELY POPS. THERE WILL BE A DISTINCT AIRMASS
CHANGE BEHIND THE FRONT. STRONG COLD AIR ADVECTION IS EXPECTED
BEHIND THE FRONT ON THURSDAY. THE MODELS TRY TO DRY THINGS OUT
QUICKLY BUT SUSPECT THAT THIS IS TOO FAST. WILL LIKELY SEE A FAIR
AMOUNT OF CLOUDINESS AND PERHAPS A FEW SHOWERS DOWN WIND OF THE
LAKE. AFTER TUESDAY HAVE USED A BLEND OF GUIDANCE TEMPS.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
TROUGH ALOFT FRIDAY WITH A VERY COOL AIRMASS. STILL GOOD CONSENSUS
THAT H8 TEMPS WILL BE BETWEEN +2C AND +5C. WILL KEEP THE HIGHS IN
THE 60S BOTH FRIDAY AND SATURDAY...WITH EVEN SOME UPPER 50S ACROSS
NW PA ON FRIDAY. FAIRLY CLOUDY TO START FRIDAY WITH ADDITIONAL LAKE
CLOUDS...BUT BY LATE AFTERNOON HIGH PRESSURE FROM THE CENTRAL LAKES
REALLY BEGINS TO BUILD IN. WILL ALSO KEEP SOME LOW PRECIP CHANCES
FOR LAKE EFFECT RAIN SHOWERS. SIGNIFICANT DRYING AND RIDGING BEGIN
TO WORK IN FOR SATURDAY...SO PRECIP SHOULD NOT BE A PROBLEM. NIGH
LOWS WILL BE COOL FOR SURE...BUT CLOUD COVER WILL BE THE DETERMINING
FACTOR ON HOW COOL. TEMPERATURE RECOVERY BEGINS SUNDAY AS THE HIGH
SHIFTS EAST AND WE GET RETURN FLOW. THE NEXT FRONTAL SYSTEM WILL BE
ACROSS THE NORTHERN AND CENTRAL LAKES COME SUNDAY.
&&
.AVIATION /10Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE AND DRY AIRMASS JUST TO OUR NORTHEAST. TO OUR
SOUTHWEST THERE IS A MORE HUMID AIRMASS AND A DEVELOPING WARM
FRONT. THE DRY AIR IN COMBINATION WITH ALL OF THE HIGH CLOUD
PRESENTLY OVER THE AREA SHOULD LIMIT ANY EARLY MORNING BR ISSUES.
ALREADY STARTING TO SEE SOME MID CLOUD DEVELOPMENT OFF THE WARM
FRONT. OBSERVATIONS ARE COMING IN BETWEEN 5K AND 7K FEET. WITH
THAT HAVE REMOVED THE MENTIONS OF 3K FEET LOCALLY AND RAISED THAT
TO VFR. WARM FRONT WILL PUSH NORTHEAST TODAY AND BRING EASTERLY
WINDS AROUND TO THE SOUTH. MOST OF OUR FORECAST MODELS WANT TO
DEVELOP A FEW SHOWERS/POSSIBLY A TS/ ACROSS THE AREA THIS
AFTERNOON. HAVE CONTINUED WITH THE SHRA MENTION IN PROB GROUPS.
RIDGE REALLY BUILDS IN MONDAY EVENING AND PRECIP CHANCES ARE
EXPECTED TO BE OVER.
OUTLOOK...NON VFR WITH POSSIBLE SHOWERS/THUNDERSTORMS WEDNESDAY
THROUGH THURSDAY. MAY HAVE SOME NON VFR CEILINGS ACROSS THE
SNOWBELT THURSDAY AND FRIDAY.
&&
.MARINE...
SOUTHERLY FLOW TODAY AND A RELATIVELY NICE DAY ON THE LAKE. THERE
MAY BE A SHOWER OR THUNDERSTORM TODAY AS A WARM FRONT PUSHES
NORTHEAST ACROSS THE LAKE. FLOW COMES AROUND TO THE SOUTHWEST
TUESDAY AND PICKS UP ENOUGH THAT A SMALL CRAFT ADVISORY MAY BE
NEEDED ALONG THE EAST HALF/END. WINDS BEGIN TO DECREASE TUESDAY
NIGHT INTO WEDNESDAY AS A WEAKENING COLD FRONT BEGINS TO SINK SOUTH
ACROSS THE CENTRAL LAKES. WINDS SHIFT TO THE NORTHWEST BY THURSDAY
MORNING. SOME OF THE BETTER COLD AIR ADVECTION IS DELAYED UNTIL
FRIDAY. AT THAT POINT WINDS WILL PICK UP AND SMALL CRAFT CONDITIONS
WILL BE LIKELY. A MUCH COOLER AIRMASS WILL BRING LAKE EFFECT RAIN
SHOWERS TOO.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...OUDEMAN
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
730 AM EDT MON SEP 9 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE REGION TODAY AND LINGER INTO MID
WEEK. A COLD FRONT WILL ARRIVE OUT OF THE NORTH LATE IN THE
WEEK...USHERING IN COOLER AIR FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 730 AM EDT MONDAY... LITTLE CHANGE IN PAST SEVERAL HOURS
ALTHOUGH DENSE FOG HAS FORMED IN SOME OF THE MOUNTAIN VALLEYS.
DISSIPATION WILL INITIALLY BE SLOW... BUT BY MID MORNING VIRTUALLY
ALL THE FOG WILL BE GONE.
PREVIOUS DISCUSSIONS...
AS OF 430 AM EDT MONDAY...LITTLE HAS CHANGED SINCE THE LAST
UPDATE AS SATELLITE DIFFERENCE PRODUCT CONTINUES TO INDICATE
SCATTERED MID/HIGH CLOUDS ACROSS THE PIEDMONT REGIONS...AND
LOW/MID STRATUS IN THE MOUNTAIN VALLEYS. OTHERWISE...ADDITIONAL
FOG DEVELOPMENT HAS BEEN SLOW TO MATERIALIZE TO THIS POINT.
HOWEVER...STILL EXPECTING SOME ADDITIONAL COVERAGE BEFORE DAYBREAK
ESPECIALLY IN LOW LYING AREAS. AS FOR THE FCST...DID NOT MAKE ANY
CHANGES WITH THIS UPDATE.
AS OF 230 AM EDT MONDAY...PATCHY FOG BEGINNING TO DEVELOP ACROSS
THE REGION AT THIS TIME. DEVELOPMENT SHOULD CONTINUE AS
TEMPERATURES DROP ANOTHER DEGREE OR SO...HOWEVER NOT EXPECTING
DENSE FOG CRITERIA TO BE MET...THUS WILL NOT ISSUE DENSE FOG
ADVISORY AT THIS TIME. OTHERWISE...HIGH PRESSURE WILL CONTINUE TO
DOMINATE THE WEATHER ACROSS NORTHEAST GA AND THE CAROLINAS THROUGH
THE PERIOD. CENTRAL CONUS 590MB RIDGE WILL DRIFT EASTWARD DURING
THE DAY ON MONDAY WHILE SURFACE HIGH PRESSURE SHIFTS SOUTHWARD OUT
OF NEW ENGLAND. NORTHEASTERLY LOW LEVEL FLOW WILL VEER SOUTHERLY
DURING THE AFTERNOON HOURS AS THE SURFACE HIGH RELOCATES. MODEL
GUIDANCE DOES INDICATE MARGINAL INSTABILITY BUILDING ACROSS THE
REGION DURING THE PEAK HEATING HOURS...HOWEVER EXPECT SUBSIDENCE
FROM THE ABOVE MENTIONED RIDGE TO PREVAIL. WITH THAT SAID...WOULD
NOT BE SURPRISED TO SEE SOME FAIR WX CU DEVELOPMENT ACROSS MUCH OF
THE AREA. MOST OF THE REGION WILL REMAIN DRY WITH THE ONLY FCST
POPS BEING ALONG THE HIGH TERRAIN WHERE CHANCE POPS TAPER DOWN TO
SLIGHT CHANCE LEVELS IN THE FOOTHILLS AS UPSLOPE FLOW COMPONENT
PROVIDES LIFT IN AN OTHERWISE WEAKLY FORCED ENVIRONMENT. EXPECTING
ANY SHOWER OR THUNDERSTORM DEVELOPMENT IN THIS REGION TO BE ON A
DIURNAL TREND...THUS LOWERED POPS AFTER SUNSET. TEMPERATURES
DURING THE NEAR TERM PERIOD WILL REMAIN A FEW DEGREES ABOVE
NORMAL.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AT 225 AM EDT MONDAY...A DEEP LAYER RIDGE OF HIGH PRESSURE WILL BE
SITUATED OVER THE FORECAST AREA ON TUESDAY. MODEL SOUNDINGS ARE
STRONGLY CAPPED OUTSIDE OF THE MOUNTAINS. I LOWERED POPS A
HAIR...BUT I DID RETAIN SLIGHT CHANCE TO LOW END CHANCE POPS OVER
THE HIGH TERRAIN. I SUSPECT THAT EVEN THIS MIGHT BE TOO HIGH. MAX
TEMPS WILL RUN A FEW DEGREES ABOVE NORMAL. THE RIDGE WILL WEAKEN A
LITTLE ON WEDNESDAY AND BOTH THE GFS AND ECMWF GENERATE MORE PCPN
OVER THE MTNS. THIS SEEMS REASONABLE AND THE DAY SHIFT HAD THIS WELL
IN HAND WITH 30/40 POPS OVER THE MOUNTAINS AND SLIGHT CHANCE OR
LOWER POPS ACROSS THE PIEDMONT.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 250 AM MONDAY...A COLD FRONT IS STILL EXPECTED TO PUSH
ACROSS THE REGION SOMETIME ON THURSDAY. AS THE PREVIOUS SHIFT
MENTIONED...THE FORCING ALONG THE FRONT ISN/T THAT STRONG WITH WEAK
WIND SHEAR AND MODEST INSTABILITY. LOW CHANCE POPS WERE
RETAINED...BUT THERE IS NO INDICATION THAT ANY KIND OF ORGANIZED
SEVERE THREAT WILL ACCOMPANY THE FRONT. CONVERGENCE WILL SHIFT SOUTH
OF THE REGION FRIDAY AND THROUGH THE WEEKEND. TEMPERATURES WILL
GRADUALLY COOL AND THE AIRMASS WILL BECOME DRIER AS HIGH PRESSURE OF
CANADIAN ORIGINS PUSHES INTO THE FORECAST AREA.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AT KCLT...NO CHANGES FROM PREVIOUS FORECAST. VFR CONDITIONS WILL
PREVAIL THROUGH THE TAF PERIOD AS HIGH PRESSURE DOMINATES. UPPER
LEVEL RIDGE WILL CONTINUE TO SHIFT EAST THROUGH THE PERIOD WHILE
SURFACE HIGH PRESSURE LOCATED OVER NEW ENGLAND EXTENDS TO THE
SOUTHEAST. AS THE PERIPHERY OF THE RIDGE LOWERS INTO THE MID
ATLANTIC STATES INTRODUCED LIGHT SOUTHERLY WINDS LATE IN THE PERIOD.
OTHERWISE... THERE WILL BE ENOUGH INSTABILITY ACROSS THE PIEDMONT TO
PRODUCE SOME FAIR WX CU DURING THE PEAK HEATING HOURS. OTHER THAN
THAT SHOULD BE A QUIET FORECAST PERIOD.
ELSEWHERE...IFR FOG AT KAVL UNTIL APPROXIMATELY 14Z. OTHERWISE...
AFTER INITIAL PATCHY FOG BURNS OFF BEYOND SUNRISE... CONDITIONS WILL
IMPROVE TO VFR LEVELS AT ALL SITES AND REMAIN THERE THROUGH THE
DAY. LATEST HRRR AND 4KMWRF INDICATE THAT THE POSSIBILITY REMAINS
FOR SCATTERED SHOWERS ALONG THE MOUNTAINS AS UPSLOPE FLOW AIDS
WEAKLY FORCED ENVIRONMENT...HOWEVER STILL NOT CONFIDENT ENOUGH TO
ADD AT KAVL AT THIS TIME. DID INCLUDE MVFR RESTRICTIONS ON TUESDAY
MORNING AT KAND AND KHKY WHILE IFR RESTRICTIONS ARE HIGHLIGHTED AT
KAVL FOR FOG. WINDS THROUGH THE PERIOD SHOULD REMAIN GENERALLY
LIGHT AND WILL VEER SOUTHERLY DURING THE AFTERNOON/EVENING HOURS.
OUTLOOK...WEAK HIGH PRESSURE WILL REMAIN IN PLACE THROUGH MID WEEK
WITH WITH AFTERNOON/EVENING SHOWERS AND STORMS POSSIBLE. A STRONGER
FRONT WILL MOVE OVER THE AREA LATE IN THE WEEK.
CONFIDENCE TABLE...
11-17Z 17-23Z 23-05Z 05-11Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 95% HIGH 100% HIGH 100% HIGH 91%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 87%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...MCAVOY
NEAR TERM...CDG
SHORT TERM...MCAVOY
LONG TERM...MCAVOY
AVIATION...CDG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
607 AM CDT MON SEP 9 2013
.AVIATION UPDATE...FOR 12Z TAF PACKAGE...
SHORTWAVE IS PRODUCING WEAK STORMS IN VICINITY OF KCKV AND KBNA
THIS MORNING AT TAF ISSUANCE. RADAR TRENDS SHOW MOSTLY JUST RAIN.
MAY SEE SOME FURTHER DEVELOPMENT THIS MORNING AS AREA OF LIFT GETS
CLOSER BUT MODELS DO NOT HAVE THIS FEATURE REACHING FAR ENOUGH
SOUTHEAST TO IMPACT KBNA SO LEFT TEMPO GROUP AND STUCK WITH JUST
VCSH. OTHERWISE...VFR EXPECTED.
&&
.PREV DISCUSSION... /ISSUED 257 AM CDT MON SEP 9 2013/
DISCUSSION...
WEAK VERY SUBTLE SURFACE BOUNDARY EXTENDS FROM SAINT LOUIS DOWN
THROUGH FAR WESTERN KENTUCKY INTO SOUTHERN MIDDLE TENNESSEE. WEAK
SHORT WAVE AT THE MID LEVELS OVER FAR WESTERN KENTUCKY CAN BE SEEN
IN 00Z EURO AT 06Z AND TO SOME EXTENT IN THE LASTEST RUC LOOP OF 700
MBAR COLD TEMP AXIS. AGAIN VERY SUBTLE FEATURES. ISOLATED CONVECTION
DEVELOPED JUST AFTER MIDNIGHT IN FAR NORTHWEST MIDDLE TENNESSEE
AND HAS MOVED LITTLE LAST COUPLE OF HOURS. 500 MBAR HIGH TO OUR
WEST WILL WORK EASTWARD TODAY KEEPING SUBSIDENCE ACROSS THE AREA
AND WITH LITTLE IN THE WAY OF FORCING SO AM EXPECTING TO SEE ONLY
ISOLATED CONVECTION ONCE AGAIN. THINK AREAS WEST OF INTERSTATE 65
MIGHT BE FAVORED BUT AGAIN LOW POPS. SURFACE BOUNDARY WILL LIFT
NORTH TODAY WHILE SHORT WAVE DAMPS OUT. THIS WILL PLACE MID STATE
PRETTY MUCH IN THE GRIPS OF UPPER LEVEL RIDGING WITH LOW POP
CHANCES FOR CONVECTION BOTH DURING THE DAY AND NOCTURNALLY AT
LEAST THROUGH WEDNESDAY. BY THURSDAY A SURFACE FRONT WILL BE
MAKING ITS WAY SOUTHWARD FROM GREAT LAKES REGION AND THIS WILL
INCREASE POPS FOR THURSDAY AND THURSDAY NIGHT. WITH ALL THE
RIDGING IN PLACE OF RECENT DAYS AND CONTINUED OFF CONTINENT WIND
FLOW I JUST DONT SEE MUCH IN THE WAY OF MOISTURE TO FEED THIS
SOUTH BOUND SYSTEM SO AM EXPECTING RAINFALL AMOUNTS TO LIKELY BE
LOW. FRONT GETS SOUTH OF MID STATE ON FRIDAY WITH 1024 SURFACE
HIGH CENTERED OVER LAKE SUPERIOR. COOLER AND MORE SEASONABLE TEMPS
WILL FOLLOW FRONTAL PASSAGE. SURFACE HIGH WILL RIDGE DOWN ACROSS
THE MID STATE THROUGH THE WEEKEND.
AS FOR TEMPS...MET IS RUNNING 2 TO 4 DEGREES COOLER THAN MAV FOR
DAYTIME HIGHS THROUGH WEDNESDAY AND KEEPS TRYING TO GO TOWARD
CLIMATOLOGY WHILE MAV IS WANTING TO KEEP THINGS MORE HEATED. I
BASICALLY KNOCKED ONE TO TWO DEGREES OFF THE MAV FOR DAYTIME HIGHS
THROUGH WEDNESDAY OR CLOSER TO AVERAGE OF THE TWO MODELS. BOTH MET
AND MAV ARE CLOSE ON NIGHTTIME LOWS THROUGH WEDNESDAY SO I FOLLOWED.
FOLLOWING FRONTAL PASSAGE EXPECT HIGHS ON FRIDAY TO BE A GOOD 10
DEGREES COOLER THAN WHAT WE HAVE BEEN SEEING. TEMPS FRIDAY THROUGH
THE WEEKEND WILL BE IN THE LOW TO MID 80S WITH MID AND UPPER 70S
ALONG THE UPPER CUMBERLAND.
BOYD
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
TB12
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
1142 AM EDT MON SEP 9 2013
.SYNOPSIS...
A WEAK COOL FRONT WILL DRIFT SOUTH INTO THE CAROLINAS TODAY AND
GRADUALLY DISSIPATE THIS EVENING. HIGH PRESSURE BUILDING NORTH OF
THE AREA WILL WEDGE SOUTH ALONG THE APPALACHIANS THIS MORNING
BEFORE SLIDING QUICKLY EAST AND OFFSHORE THE MID ATLANTIC COAST
THIS AFTERNOON. HIGH PRESSURE ALOFT SLIDES EAST INTO THE AREA BY
TUESDAY BRINGING A RETURN TO MORE SUMMERLIKE WEATHER FOR MID WEEK
AHEAD OF A STRONG COLD FRONT THAT ARRIVES ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1140 AM EDT MONDAY... INCREASED CLOUD COVER FOR THIS
AFTERNOON AND LOWERED TEMPERATURES. CLOUDS AND LOW LEVEL COOL POOL
ARE BANKING UP AGAINST THE BLUE RIDGE RIDGE WITH CU FIELD
DEVELOPING ALONG SOUTHERN PORTIONS OF CWA WHERE THERE WAS SOME
MORNING SUNSHINE. SHAPED THE AFTERNOON POPS TOWARDS THE HRRR WITH
CONVECTION ACROSS HIGHER TERRAIN AND SPOTTY ACTIVITY IN THE EAST.
MORE ADJUSTMENTS THIS AFTERNOON...
AS OF 910 AM EDT MONDAY...
WITH THIS MORNING RNK 12Z/8AM SOUNDING SHOWING SHALLOW MOISTURE
UP TO 870 MB...EXPECT CLOUD COVER TO PERSIST FOR A COUPLE OF HOURS
THIS MORNING WITH THE WEAK FRONT AND LOW LEVEL WEDGE. WITH THIS
RICH CLOUD COVER...LOWERED TEMPERATURES FOR THIS MORNING INTO
THIS AFTERNOON. ISOLATED TO SCATTERED POPS SUPPORTED BY
ECMWF...GFS NAM...MAINLY ACROSS THE HIGHER TERRAIN. 06Z RNK WRF
ARW PLACED THE FOCUS OF CONVECTION ACROSS THE NORTHWEST
MOUNTAINS. WILL SHAPE POPS AND ISC GRIDS AS MORNING PROGESSES.
AS OF 230 AM EDT MONDAY...
FORECAST REMAINS RATHER UNCERTAIN OVER THE NEXT 24 HOURS WITH
A WEAK FRONT DROPPING TO THE SOUTH THIS MORNING AND A LOW LEVEL
WEDGE DEVELOPING BEHIND THE BOUNDARY ALONG THE MOUNTAINS INTO
THIS AFTERNOON. KEY IS WHETHER OR NOT ANY LOW CLOUDS DEVELOP
WITHIN THE LOW LEVEL COOL POOL THIS MORNING AND BANK UP ALONG THE
BLUE RIDGE LONGER THAN EXPECTED DESPITE HIGH PRES EXITING OFF TO
THE NE AFTER MIDDAY. MODELS CONTINUE TO SUGGEST THIS SCENARIO WITH
ONGOING ISOLATED -SHRA FADING OUT EAST BY DAYBREAK ONLY TO HAVE
LOW CLOUDS SPILL BACK WEST AIDED BY WEAK UPSLOPE. THEREFORE HAVE
TRENDED CLOUDIER EARLY ON EASTERN HALF WITH LESS CLOUDS WEST
WHERE EARLY FOG/STRATUS MORE PREVALENT.
LOW LEVEL FLOW WILL GRADUALLY VEER AROUND TO THE SOUTH/SW FROM
WEST TO EAST THIS AFTERNOON AS THE HIGH EXITS WITH INCREASING
WEAK MOISTURE CONVERGENCE FAR WEST. HOWEVER MAY STILL SEE A WEAK
RESIDUAL WEDGE HANG IN OUT EAST PER SUBTLE SE FLOW AND LINGERING
STABILITY OFF GUIDANCE. THIS SHOULD KEEP ANY ADDED SHRA CONFINED
TO THE MOUNTAINS WHERE MODELS DEPICT BEST AXIS OF THETA-E AND
DECENT CAPES AHEAD OF PERHAPS A WEAK MID LEVEL WAVE SPILLING IN
FROM THE NW LATE. THIS COULD BE ENOUGH TO SPARK MAINLY ISOLATED
SHRA/TSRA BUT IFFY GIVEN LACK OF MUCH LOW LEVEL FOCUS...BUILDING
5H HEIGHTS FROM THE WEST AND ONLY SHALLOW MOISTURE. THUS STAYING
WITH 20/30 POPS WEST WHICH MESHES BEST WITH THE LATEST ENSEMBLES
AND DRY EAST WHERE CLOUDS MAY LINGER. HIGH TEMPS TRICKY PENDING
TIMING OF MORE INSOLATION EAST AND WEAK VEERING FLOW FOLLOWING A
WARM START. IF CLOUDS LOCK IN ACROSS THE NE THEN MAY BE TOUGH TO
REACH 80...WHILE ELSW COULD ZOOM UP ESPCLY WEST GIVEN WEAK
DOWNSLOPING SO BUMPED UP HIGHS THERE AND TRIMMED BACK OUT EAST.
UPPER RIDGE OVER THE MIDWEST SHIFTS EAST OVERNIGHT AS THE SURFACE
HIGH EXITS FARTHER EAST WHILE ELONGATING BACK INLAND TO OVER THE
CAROLINAS LATE. THIS SHOULD ALLOW FOR A WEAK SUBSIDENCE REGIME TO
LINGER WITH ANY RESIDUAL EVENING SHRA FROM EARLIER OUTFLOW...AND
POSSIBLY ISOLATED SHRA ACROSS THE FAR NW WITH ANY FAINT IMPULSE
SPILLING SE OVERNIGHT. OTRW PC NORTH/WEST TO CLEAR ELSW WITH
THINGS A BIT MORE MUGGY GIVEN LOWS MAINLY IN THE 60S.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM EDT MONDAY...
UPPER RIDGE CONTINUES TO BUILD OVER THE REGION ON TUESDAY WITH
AN BERMUDA HIGH PATTERN MAINTAINING ITSELF THROUGH WEDNESDAY. FOR
THE REGION THIS WILL MEAN A RETURN OF LOW LEVEL MOISTURE INTO THE
REGION AND DIURNAL SHOWERS AND STORMS DEVELOPING...ESPECIALLY OVER
THE MOUNTAINS. TEMPERATURES WILL ALSO TREND WARMER. DAYTIME HIGHS
IN THE UPPER 80S TO AROUND 90 WILL BE COMMON ACROSS THE PIEDMONT
WITH A MIX OF UPPER 70S TO MID 80S IN THE MOUNTAINS. OVERNIGHT
LOWS WILL BE IN THE LOW TO MID 60S.
THE UPPER RIDGE BEGINS TO BECOME DISPLACED WESTWARD IN RESPONSE A
DEEPENING TROUGH ACROSS THE GREAT LAKES REGION BY WEDNESDAY NIGHT.
THIS TROUGH IS PROGGED TO DEEPEN ACROSS THE EAST COAST BY THURSDAY
AND BRING AN ASSOCIATED COLD FRONT THROUGH THE REGION BY THURSDAY
EVENING. THE RESULT WILL BE A MORE ORGANIZED SERIES OF SHOWERS
AND STORMS DEVELOPING BOTH OVER THE AREA...AND ALSO MOVING INTO
THE REGION IN ASSOCIATION WITH THE FRONT. TEMPERATURES WILL ONLY
BE SLIGHTLY COOLER DURING THE DAY THURSDAY COMPARED TO THE
PREVIOUS TWO DAYS THANKS MAINLY TO MORE CLOUDS AND MORE
PRECIPITATION. LOWER DEW POINT AIR MOVES INTO THE AREA BEHIND THE
FRONT THURSDAY NIGHT...AND THUS ALLOW FOR COOLER LOW TEMPERATURES.
MID TO UPPER 50S ARE EXPECTED ACROSS THE MOUNTAINS WITH LOWER 60S
ACROSS THE PIEDMONT.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 1230 PM EDT SUNDAY...
UPPER RIDGE RETROGRADES BACK TO THE CENTRAL PLAINS BY FRIDAY WITH A
500 MB TROF DIGGING IN THE EASTERN UNITED STATES. ECMWF CLOSES OFF
AN UPPER LOW OVER NEW ENGLAND ON SATURDAY WHILE THE GFS IS FASTER
MOVING THE LONG WAVE TROF OFFSHORE. EITHER WAY...NET RESULT WILL
STILL BE NORTHWEST FLOW FOR THE FORECAST AREA.
BOTH THE ECMWF AND GFS ENSEMBLES HAVE SIMILAR TIMING WITH A SURFACE
COLD FRONT CROSSES THROUGH THE COUNTY WARNING AREA ON THURSDAY.
SOUTHWEST WINDS ON THURSDAY WILL KEEP TEMPERATURES ABOVE NORMAL AND
WILL BRING DEEP MOISTURE INTO THE AREA AHEAD OF THE FRONT. A LARGE
HIGH PRESSURE SYSTEM...ALONG WITH A COOLER AND DRIER AIRMASS BUILDS
IN BY SATURDAY. APPEARS THAT 850MB TEMPERATURES WILL LOWER IN THE +8
TO +10 RANGE BEHIND THE FRONT.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
AS OF 640 AM EDT MONDAY...
MAIN CONCERNS CONTINUE WITH THE EXTENT OF LOW CIGS IN THE WAKE OF
THE FRONT ACROSS THE EAST AND DENSE VALLEY FOG OVER THE WEST THIS
MORNING. LATEST SATELLITE PICS AND OBS SHOW THAT THE LOWER
STRATO-CU ALONG WITH SOME STRATUS REMAINS JUST EAST OF ROUTE 29
ATTM. HOWEVER LOWER CIGS ARE GRADUALLY SHIFTING WEST TOWARD THE
BLUE RIDGE AIDED BY INCREASING LOW LEVEL NE FLOW BEHIND THE FRONT.
THIS MAY PUSH MVFR/IFR CIGS SOUTH AND WEST TO KROA/KDAN EARLY THIS
MORNING WITH LINGERING LOW IFR/MVFR AT KLYH LIKELY THROUGH MUCH OF
THE MORNING. STILL LOW CONFIDENCE IN JUST HOW FAR WEST THIS CANOPY
WILL GET BEFORE STARTING TO MIX OUT WITH HEATING BY MID/LATE
MORNING. SINCE APPEARS THE BLUE RIDGE MAY SERVE AS THE WESTERN
EXTENT OF THE MVFR CIGS...HAVE FASTER IMPROVEMENT FROM BCB WEST
WHERE MAINLY DEALING WITH IFR/LIFR IN FOG THAT SHOULD DISSIPATE A
COUPLE HOURS AFTER SUNRISE. POTENTIAL TO SEE LYH AND PERHAPS ROA
STAY SUB-VFR INTO EARLY AFTERNOON IF THE LOW DECK LOCKS IN BUT TOO
IFFY TO HOLD LOW CONDITIONS THAT LONG GIVEN WARMTH ALOFT. THUS
TRENDING EVEN THOSE LOCATIONS VFR BY MIDDAY IF NOT SOONER AT ROA.
OTRW THE FRONT WASHES OUT TO THE SOUTH LATER TODAY WITH HIGH
PRESSURE QUICKLY SHIFTING EAST AND OFF THE MID ATLANTIC COAST BY
AFTERNOON. THIS SHOULD ALLOW LOW LEVEL WINDS TO VEER AROUND TO
THE SOUTH/SW AND HELP SCOUR OUT ANY RESIDUAL LOW CLOUDS THAT MAY
BE STUCK OUT EAST IN THE AFTERNOON. THIS SHOULD LEAD TO A SCTD-
BKN 4-6KFT CU FIELD WITH MOST OF THE BKN LAYER CU DEVELOPING OVER
THE WEST ESPCLY LWB- BLF. ANY SHRA ALSO LOOKS TOO ISOLATED TO
MENTION SO KEEPING OUT OF THE TAF SITES FOR NOW.
AFTER TODAY...EXPECT A RETURN TO MORE TYPICAL SUMMERLIKE WEATHER
WITH INCREASING CHANCES FOR DIURNALLY-DRIVEN SHOWERS AND
THUNDERSTORMS. AT THIS POINT...NO WIDESPREAD EXTENDED DURATION OF
POOR AVIATION CONDITIONS ARE EXPECTED THROUGH MID WEEK...OUTSIDE
OF EARLY MORNING FOG AND PATCHY LOW STRATUS. ANOTHER COLD FRONT
WILL ARRIVE ON THURSDAY WITH PERHAPS A MORE SUBSTANTIAL BAND OF
SHOWERS AND STORMS THURSDAY AFTERNOON...WHICH MAY ALLOW FOR A
PERIOD OF SUB-VFR CONDITIONS INTO THURSDAY EVENING. MUCH DRIER AND
COOLER AIR LOOKS TO ARRIVE BEHIND THE FRONT MARKING FOR THE RETURN
OF WIDESPREAD VFR FOR THE END OF THE WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/KK
SHORT TERM...DS
LONG TERM...AMS
AVIATION...JH/PM
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
125 PM PDT MON SEP 9 2013
.SYNOPSIS...
A WEAK LOW PRESSURE TROUGH PARKED OVER THE SOUTHWEST WILL BRING
SLIGHT COOLING...BUT ALSO KEEP THE CHANCE FOR SHOWERS AND
THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS THROUGH MIDWEEK. A
SHALLOW MARINE LAYER WILL KEEP THE COASTAL AREAS COOLER...WITH AREAS
OF LOW CLOUDS AND FOG EXTENDING INTO THE WESTERN VALLEYS. TOWARD THE
END OF THE WEEK...A RIDGE OF HIGH PRESSURE BUILDING IN FROM THE WEST
WILL BRING WARMER WEATHER AND LESS MARINE CLOUDS.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
CUMULUS CLOUDS WERE BUBBLING OVER THE MOUNTAINS EARLY THIS
AFTERNOON...BUT AS OF 115 PM PDT...RADAR DID NOT INDICATE ANY
RAINFALL. THE CLOUDS WERE DRIFTING SOUTH WITH THE UPPER WINDS.
TEMPERATURES AT NOON WERE RUNNING 2 TO 6 DEGREES LOWER THAN
YESTERDAY. SFC PRESSURE GRADIENTS WERE TRENDING A BIT BETTER ONSHORE
TO THE LOWER DESERTS THAN YESTERDAY AS WELL.
MAIN CONCERN AGAIN TODAY AND FOR THE NEXT COUPLE OF DAYS WILL BE
THUNDERSTORMS. MOISTURE AND INSTABILITY LOOK SUFFICIENT FOR
DEVELOPMENT THIS AFTERNOON OVER THE ELEVATED TERRAIN DUE TO HEATING.
MODELS KEEP THE PRECIP THREAT MAINLY ALONG AND EAST OF THE MOUNTAINS
UNDER NORTHERLY FLOW ALOFT. GPS SENSORS OVER OUR LOWER DESERTS ARE
HOLDING NEAR 1.5 INCH OF PW.
ONCE THEY FIRE...THUNDERSTORMS MAY NOT END WITH DAYTIME HEATING.
SIMILAR TO LAST NIGHT...NOCTURNAL THUNDERSTORMS WILL BE POSSIBLE.
WATER VAPOR IMAGERY AT 19Z SHOWED A NARROW STRIP OF DARKENING FROM
NW OF KLAS...TO NEAR BANNING WHICH MAY MARK A WEAK UPPER-LEVEL
DISTURBANCE THAT THE NAM12 ROTATES AROUND THE WEST SIDE IF AN UPPER
LOW CENTERED NEAR BLYTHE OVERNIGHT. GIVEN THE FORECAST MID-LEVEL
INSTABILITY AND LATEST HRRR RUN...AN AREA OF CONVECTION COULD DROP
SW INTO THE COACHELLA VALLEY...SAN DIEGO COUNTY DESERTS...HIGH
DESERTS...AND ADJACENT MOUNTAINS THIS EVENING AND OVERNIGHT.
LOCALIZED FLASH FLOODING IS POSSIBLE...BUT GIVEN THE FLOW ALOFT AND
THE LOWER PWS...THE THREAT DOES NOT LOOK GREAT ENOUGH TO WARRANT A
FFA AT THIS TIME.
ALONG THE COAST...MARINE CLOUDS/STRATUS SHOULD REDEVELOP OVERNIGHT
AND SPREAD INTO THE WESTERN VALLEYS. THE SHALLOW MARINE LAYER WILL
KEEP COASTAL AREAS COOLER THAN THE PAST FEW DAYS. HOWEVER...
INLAND...ABOVE THE SHALLOW MARINE LAYER...IT WILL REMAIN QUITE WARM.
HIGH PRESSURE OVER THE GREAT PLAINS THIS AFTERNOON WILL DRIFT
EASTWARD...WHILE A WEAK LOW PRESSURE TROUGH REMAINS STATIONARY
ACROSS THE WEST. GLOBAL MODELS SHOW THE PATTERN MORPHING INTO A REX
BLOCK WITH A WEAK UPPER LOW HOLDING OVER THE SW THROUGH AT LEAST
THU. HEIGHTS DO GRADUALLY RISE OVER SOCAL AFTER MIDWEEK WITH SOME
DRYING AND WARMING. IN THE MEANTIME...LINGERING MOISTURE AND
INSTABILITY UNDER THE UPPER LOW WILL CONTINUE A THREAT OF
THUNDERSTORMS...EVEN NOCTURNALLY...AND MAINLY ALONG AND EAST OF THE
MOUNTAINS.
ONCE THE UPPER LOW FINALLY DEPARTS TO THE NE...HIGH PRESSURE BUILDS
IN ALOFT WITH A CENTER OVER/NEAR SOCAL. THIS SHOULD RESULT IN VERY
WARM WEATHER ALL THE WAY TO THE COAST AGAIN NEXT WEEKEND.
&&
.AVIATION...
092000Z...THIS EVENING...LOW CLOUDS WILL PUSH ASHORE 10 TO 15
MILES...FIRST REACHING THE COASTAL AIRPORTS BETWEEN 10/0200-0500Z
WITH BASES 900 FT MSL AND TOPS TO AROUND 1500 FT MSL. SNA WILL
BECOME BKN/OVC LATER IN THE NIGHT...AROUND 10/0800Z. VIS REDUCED
LOCALLY TO 2-5 SM EXPECTED WHERE LOW CLOUDS INTERSECT TERRAIN. LOW
CLOUDS AND FOG WILL ERODE TO THE COAST BETWEEN 10/1500Z-1700Z.
MOUNTAINS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED
ON THE MOUNTAIN RIDGETOPS AGAIN BETWEEN 09/2100-10/0600Z THIS
AFTERNOON INTO THE EARLY NIGHT. SOME OF THESE STORMS WILL MOVE
SOUTHWARD AND INTO THE COACHELLA VALLEY. BASES WILL BE AROUND 8000
FEET ASL WITH TOPS TO 40000 FEET. LOCAL VIS REDUCED IN +TSRA TO 2SM
AND GUSTY VARIABLE WINDS TO 40 MPH POSSIBLE AROUND STORMS.
OTHERWISE...SCATTERED TO BROKEN CLOUDS AOA 12000 FEET THROUGH
TONIGHT.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...JAD
AVIATION/MARINE...JT
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
400 PM MDT MON SEP 9 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 400 PM MDT MON SEP 9 2013
EXCEPTIONALLY WET PERIOD CONTINUES WITH WIDESPREAD PRECIPITATION
OCCURRING ACROSS BOTH CO AND UT WITH THIS TREND CONTINUING. WATER
VAPOR IMAGERY CURRENTLY SHOWING ANOMALOUS AMOUNTS OF MOISTURE
STREAMING UP FROM THE SOUTH WHILE A DEFORMATION AXIS HAS SET UP
OVER NEVADA INTO NRN UTAH. THIS AXIS IS ALLOWING MOISTURE AND
IMPULSES TO CONTINUE STREAMING INTO OUR AREA. LATEST GUIDANCE TO
INCLUDE THE NAM...RAP AND HRRR SHOW PRECIP CONTINUING THROUGH
TONIGHT AND THEN A RELATIVE LULL BEFORE ANOTHER WAVE CAUSES PRECIP
AGAIN DURING THE MORNING HOURS TOMORROW. WITH PLENTY OF RAIN
HAVING ALREADY FALLEN AND MORE ON THE WAY...EXTENDED THE FLASH
FLOOD WATCH THROUGH TUESDAY NIGHT AND ALSO ADDED THE UNCOMPAGHRE
AND ROAN/TAVAPUTS PLATEAUS SINCE THEY SAW THE BULK OF PRECIP
TODAY. SO FAR ONLY A FEW AREAS (PORTIONS OF ARCHES AND CANYONLANDS
NATIONAL PARK) HAVE REPORTED FLOODING DUE TO THE MAINLY STRATIFORM
NATURE OF THE PRECIP THOUGH A FEW EMBEDDED STORMS HAVE FIRED THIS
AFTERNOON. THE BIGGEST CONCERN HAS BEEN...AND CONTINUES TO
BE...SERN UTAH DUE TO THE SLOT CANYON AND DESERT TERRAIN. LOTS OF
CLOUDS HAVE INHIBITED CONVECTION SO FAR TODAY THOUGH VIS IMAGERY
DOES SHOW SOME BREAKS STARTING TO FORM. WILL ALERT NEXT SHIFTS TO
KEEP AN EYE ON AREA. MOST TEMPS ARE RUNNING ABOUT 5 TO 10 DEGREES
COOLER THAN NORMAL DUE TO RAINFALL AND CLOUDS.
OVERNIGHT...SOME MODELS DEPICT MORE STEADY PRECIP TO
CONTINUE...ESPECIALLY FOR THE ABAJOS...LA SALS AND
UNCOMPAGHRE/ROAN/TAVAPUTS PLATEAUS. OTHER MODELS SHOW MORE OF A
LULL. KEPT PRECIP IN FORECAST AS MOISTURE WILL CONTINUE TO STREAM
OVERHEAD AND ANY WEAK DISTURBANCE/IMPULSE WILL CREATE SHOWERS. FOR
TOMORROW THOUGH...MORE IMPULSES WILL CONTINUE TO MOVE OVER THE CWA
WITH WHAT APPEARS TO BE A SIGNIFICANT IMPULSE MOVING INTO THE 4
CORNERS BY 7AM AND THEN SPREADING NWRD BY NOON. FOR TUESDAY
THEN...ANOTHER DAY LIKE TODAY...CLOUDS...RAIN...COOL TEMPERATURES
WITH INCREASED FLOODING CONCERNS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 400 PM MDT MON SEP 9 2013
THE MAIN STORM TRACK WITH THE STRONGER WESTERLIES WILL REMAIN WELL
TO THE NORTH OF THE INTERMOUNTAIN WEST THROUGH THIS EXTENDED PERIOD.
BY WEDNESDAY STRONG TROUGHING INTO THE GREAT LAKES REGION AND INTO
THE GULF OF ALASKA LEAVES AN AMPLIFIED RIDGE OVER THE NORTHERN US
AND CANADIAN ROCKIES. THIS NORTHERN RIDGE WILL LEAD TO A REX PATTERN
DUE TO AN AREA OF LOW PRESSURE THAT GETS CUT OFF....AND WILL WOBBLE
AROUND THE GREAT BASIN. THIS LOW WILL BE HELD FROM MOVING WEST TO
EAST BY THE SUBTROPICAL HIGH OVER THE SOUTHEAST STATES AND PACIFIC
HIGH PRESSURE BUILDING TOWARD THE WEST COAST. THIS PATTERN WILL BE
STATIC THROUGH AT LEAST THURSDAY AFTER WHICH MEDIUM RANGE MODELS
SWING SOME STRONGER ENERGY INTO WESTERN CANADA...BREAKING THE REX
BLOCK...AND ALLOWING THE GREAT BASIN LOW TO TO BEGIN TO LIFT
NORTHWARD. HOWEVER THERE ARE MODEL CONFLICTS WITH HOW THIS LOW
INTERACTS WITH THE ENERGY BREAKING DOWN THE RIDGE BY LATE IN THE
FORECAST...LEAVING VERY LOW CONFIDENCE IN THE LATTER PERIODS SO
BLENDED MODELS GENERALLY FOLLOWED.
SO TO FOCUS ON THE PERIOD WHEN THE UPPER LOW IS CUTOFF IN THE GREAT
BASIN WEDNESDAY AND THURSDAY. THE MODELS ARE SIMILAR IN LIFTING ONE
LOBE OF STRONGER ENERGY NORTHWARD OUT OF OUR CWA ON
WEDNESDAY...WHILE ROTATING ANOTHER STRONG PIECE ACROSS UTAH ON
THURSDAY. SUBSIDENCE BEHIND THE FIRST WAVE WILL GENERALLY BRING
SOMEWHAT OF A DOWNTURN TO THE PRECIPITATION FOR WEDNESDAY...WITH THE
FAMILIAR PATTERN OF STORMS FOCUSING ON THE TERRAIN BY EARLY
AFTERNOON BEFORE SPREADING INTO THE VALLEYS. ASCENT WILL BEGIN TO
INCREASE SIGNIFICANTLY ON THURSDAY AFTERNOON OVER OUR CWA THURSDAY
WITH THE DYNAMIC TROP DIPPING DOWN TOWARD 400MB WHICH SHOULD ENHANCE
THE INSTABILITY AND BRING AN UPTURN TO STORMS FOR THURSDAY. THE
STRONGER MONSOON PLUME WILL GET DISRUPTED BUT STILL PLENTY OF
MOISTURE AROUND FOR MAKING STORMS. THE DRY CONVEYOR BELT ASSOCIATED
WITH THE PV LOBE MAY ALSO LEAD TO SOME STRONGER STORM DEVELOPMENT.
FROM FRIDAY ONWARD THE LOW WILL HAVE LIFTED NORTH AND EAST OF OUR
AREA BUT A RESIDUAL TROF REMAINS IN PLACE. MOISTURE WILL BEGIN TO
WANE BUT PWATS STILL HOVER AROUND OR JUST ABOVE NORMAL FOR MID
SEPTEMBER AND THIS WILL KEEP A THREAT OF SHOWERS AND THUNDERSTORMS
GOING INTO THE LATE PERIODS. TEMPERATURES THROUGH THE EXTENDED
PERIOD LOOK TO HOVER NEAR THE SEASONAL NORMALS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 400 PM MDT MON SEP 9 2013
RAINFALL CONTINUES THIS AFTERNOON AND FOR MUCH OF THE NEXT 24
HOURS. MVFR AND OCCNL IFR IS EXPECTED THROUGH TOMORROW MORNING
WITH LOW CIGS AND VIS UNDER THE STRONGER SHOWERS AND STORMS THAT
FORM. FOG WILL ALSO BE A CONCERN ESPECIALLY IN THE MORNING DUE TO
AMOUNT OF MOISTURE IN THE AIR. ALL TAF SITES ARE UNDER THE GUN FOR
PRECIP...LOW CLOUDS AND VISIBILITIES THROUGH 00Z TOMORROW.
MOUNTAIN OBSCURATIONS CAN BE EXPECTED OVER ALL HIGHER TERRAIN.
&&
$$
SHORT TERM...TGR
LONG TERM...15
AVIATION...TGR
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
142 PM EDT MON SEP 9 2013
.PREV DISCUSSION...
UPDATE...
/ISSUED 1103 AM EDT MON SEP 9 2013/
FORECAST IS ON TRACK SO ONLY A FEW MINOR CHANGES IN THE UPDATE TO
ACCOUNT FOR HOURLY TRENDS. MAIN UNCERTAINTY THIS AFTERNOON IS IN
TERMS OF PRECIP. HRRR MAY BE OVER DOING CONVECTION TODAY AND IS
TRYING TO DEVELOP ACTIVITY ACROSS EVEN THE ATL METRO AREA BY 17Z
HOWEVER THE OTHER MODELS SUCH AS THE LOCAL WRF ARE VERY LIMITED ON
CONVECTIVE ACTIVITY TODAY. THINK THE BEST CHANCES REMAIN ACROSS
FAR NORTH GEORGIA AND IN PARTICULAR ACROSS NORTHWEST
GEORGIA...CLOSER TO THE SHORTWAVE.
11
SHORT TERM /TODAY THROUGH TONIGHT/...
/ISSUED AT 345 AM EDT MON SEP 9 2013/
ISOLATED SHOWERS CONTINUE TO DEVELOP ACROSS PARTS OF CENTRAL GA
EARLY THIS MORNING AND MAY NEED TO CONTINUE SMALL CHANCE POPS INTO
THE MORNING HOURS. SOME SLIGHT DIFFERENCES BETWEEN THE GFS AND THE
NAM/ECMWF MIX FOR THE SHORT TERM...MAINLY IN THE LOCATION OF THE
DEEPEST MOISTURE. ALL MODELS SHOW A SHORT WAVE OVER TN. THE GFS
HOLDS THE S/W OVER TN/NRN AL WHILE THE NAM/ECMWF BRINGS IT TO THE
NORTHWEST GA BORDER ALONG WITH SOME DEEPER MOISTURE. WITH THE RETURN
OF AN EASTERLY FLOW BRINGING IN ATLANTIC MOISTURE...THE RISK OF
CONVECTION IS SLIGHTLY GREATER THAN SUNDAY WITH A BETTER CHANCE NEAR
THE VICINITY OF THE S/W AND THEREFORE HAVE GONE WITH CHANCE POPS
OVER NORTHWEST GA. CONVECTION SHOULD DISSIPATE AFTER SUNSET. WINDS
WILL BE EASTERLY THROUGH THE SHORT TERM AND THEREFORE EXPECT MAX
TEMPS TODAY TO BE AT OR PERHAPS A DEGREE OR TWO LOWER THAN SUNDAYS
MAX TEMPS.
17
LONG TERM /TUESDAY THROUGH SUNDAY/...
/ISSUED AT 345 AM EDT MON SEP 9 2013/
A WEAKNESS IN THE UPPER RIDGE AND ASSOCIATED MOISTURE WILL GIVE SOME
CHANCES FOR SHOWERS AND THUNDERSTORMS OVER MAINLY FAR N GA TUESDAY
AFTERNOON. NOT SURE THE MODELS HAVE A GOOD HANDLE ON THIS AND THERE
COULD BE SOME CHANCE FOR MEASURABLE PRECIP TUESDAY MORNING. OVERALL
INSTABILITY IS WEAK AND THE PRECIP COULD BE ONLY SHOWERS.
THE SAME WEAKNESS THAT DOES NOT APPEAR TO BE HANDLED VERY WELL BY
THE MODELS AND ASSOCIATED MOISTURE COULD CAUSE SOME SHOWERS AND
THUNDERSTORMS OVER MAINLY FAR N GA ON WEDNESDAY AFTERNOON AND MOST
SO OVER THE NE MOUNTAINS WHERE THE BEST INSTABILITY IS FORECAST.
A COLD FRONT APPROACHES N GA LATE THURSDAY GIVING A CHANCE OF
SHOWERS AND THUNDERSTORMS OVER MAINLY N GA. FRONT EXPECTED TO MOVE
INTO N GA THURSDAY NIGHT/FRIDAY MORNING AND TO S GA SATURDAY
MORNING. THIS WILL CONTINUE THE CHANCE OF SHOWERS AND THUNDERSTORMS
FOR MUCH OF THE AREA ON FRIDAY AND MAINLY FOR CENTRAL GA ON
SATURDAY. MODELS INCONSISTENT WITH MOISTURE RETURN ON SATURDAY NIGHT
AND SUNDAY WITH THE GFS INCREASING SIGNIFICANT MOISTURE MUCH MORE
THAN THE EUROPEAN FROM STRONGER EAST FLOW OFF THE ATLANTIC. DUE TO
THE UNCERTAINTY WILL NEED TO INDICATE SMALL POPS OVER CENTRAL AND
PORTIONS OF N GA FOR SHOWERS ONLY ON SUNDAY.
HIGH TEMPERATURES GENERALLY RUNNING SLIGHTLY ABOVE NORMAL TUESDAY
THROUGH THURSDAY THEN AROUND 5 DEGREES BELOW NORMAL SATURDAY AND
SUNDAY.
BDL
&&
.AVIATION...
18Z UPDATE...
STARTING TO SEE CONVECTION DEVELOP ACROSS NORTH GEORGIA AND
EASTERN ALABAMA. WITH ONLY ABOUT A 20 PERCENT CHANCE OF CONVECTION
AT CSG AND ATL TAF SITES...HAVE OPTED TO LEAVE MENTION OF TSRA OUT
OF TAFS BUT WILL HAVE TO CLOSELY MONITOR TRENDS. STILL EXPECT BEST
CHANCES TO REMAIN NORTH AND WEST OF THE TAF SITES. MODELS ARE
INDICATING SOME LOW CLOUDS ARE POSSIBLE TOMORROW
MORNING...FEW010...BUT CONFIDENCE IS LOW.
//ATL CONFIDENCE...18Z UPDATE...
HIGH CONFIDENCE ON VSBYS AND WIND. HIGH CONFIDENCE ON CIGS EXCEPT
FOR LOW CONFIDENCE TOMORROW MORNING. MEDIUM CONFIDENCE ON
CONVECTION NOT OCCURRING AT ATL.
11
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 89 66 89 68 / 20 10 10 0
ATLANTA 90 70 88 69 / 20 10 10 5
BLAIRSVILLE 82 64 85 64 / 20 20 20 20
CARTERSVILLE 90 66 89 65 / 20 20 20 5
COLUMBUS 93 71 90 70 / 20 10 5 5
GAINESVILLE 87 68 88 68 / 20 20 20 5
MACON 92 66 90 68 / 20 10 5 5
ROME 91 67 90 66 / 30 20 20 5
PEACHTREE CITY 90 66 88 66 / 20 10 10 5
VIDALIA 91 68 91 69 / 20 10 5 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...11
LONG TERM....39
AVIATION...11
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1249 PM EDT MON SEP 9 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL DISSIPATE NORTH OF THE AREA TODAY AS HIGH
PRESSURE BUILDS IN FROM THE NORTH. HIGH PRESSURE WILL THEN PREVAIL
THROUGH THE MIDDLE OF THE WEEK BEFORE A BACKDOOR COLD FRONT DROPS
ACROSS THE AREA FRIDAY AND FRIDAY NIGHT. COOLER HIGH PRESSURE WILL
THEN BUILD INTO THE REGION FROM THE NORTH INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE FORECAST IS ON TRACK. A FEW LIGHT SPRINKLES HAVE BEEN DETECTED
BY KCLX...BUT THESE REALLY ARE NOT AMOUNTING TO TOO MUCH.
A VERY WEAK BACKDOOR FRONT MOVING SOUTH ACROSS NORTH CAROLINA WILL
DISSIPATE NORTH OF THE AREA TODAY. LIGHT WINDS WILL BECOME ONSHORE
THIS AFTERNOON AS HIGH PRESSURE BUILDS SOUTH AND A MODEST SEA
BREEZE CIRCULATION TAKES HOLD. A NUMBER OF THE HIGHER RESOLUTION
MODELS INCLUDING THE H3R...4KM NSSL WRF AND RAP ARE SPITTING OUT
ISOLATED SHOWERS/TSTMS ALONG THE SEA BREEZE FOR 1-2 HOURS THIS
AFTERNOON. NOT COMPLETELY CONVINCED ACTIVITY WILL FIRE AS IT
APPEARS THEY MAY BE OVER DEVELOPING THE CUMULUS FIELD ALONG THE
LEADING EDGE OF THE THERMALLY DIRECT CIRCULATION. PLAN TO KEEP THE
FORECAST DRY FOR NOW...ALTHOUGH SOME SMALL...SINGLE DIGIT GRIDDED
POPS WILL BE PLACED ALONG AND AHEAD OF THE SEA BREEZE FOR THE
AFTERNOON HOURS. SHOULD ANY SHOWERS/TSTMS DEVELOP...THEY WILL BE
SHORT LIVED GIVEN THE AMOUNT OF DRY AIR NOTED ALOFT. OVER THE
WATER...AN ISOLATED SHOWER WILL BE POSSIBLE THROUGH LATE THIS
MORNING ALONG A LINGERING LAND BREEZE CIRCULATION THAT IS NOTED
ABOUT 5 NM OFFSHORE.
A DECENT CUMULUS FIELD DEVELOP PRIOR TO NOON...BUT SHOULD CLEAR
OUT FROM EAST-WEST AS THE SEA BREEZE MOVES INLAND. HIGHS WILL FROM
THE LOWER 90S INLAND TO THE MID 80S AT THE BEACHES LOOK ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
TONIGHT...HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE NORTH
WITH DRY CONDITIONS EXPECTED. JUST A REAL SMALL CHANCE OF A SHOWER
NEAR THE COAST LATE AS A WEAK COASTAL TROUGH ATTEMPTS TO DEVELOP.
OTHERWISE...LOWS SHOULD RANGE FROM THE UPPER 60S INLAND TO THE
MID 70S AROUND THE COAST.
TUESDAY THROUGH THURSDAY...EXPANSIVE UPPER LEVEL RIDGING WILL
PREVAIL OVER THE SOUTHEAST U.S. TUESDAY AND TUESDAY NIGHT...BUT
THEN AN INVERTED UPPER LEVEL TROUGH WILL RETROGRADE TOWARD THE
SOUTHEAST COAST WEDNESDAY AND WEDNESDAY NIGHT CAUSING THE EASTERN
PERIPHERY OF THE RIDGE TO ERODE. A LONGWAVE UPPER LEVEL TROUGH
WILL THEN BEGIN TO BECOME ESTABLISHED OVER THE EASTERN U.S. ON
THURSDAY. MEANWHILE AT THE SURFACE...HIGH PRESSURE WILL BUILD INTO
THE REGION FROM THE NORTH THROUGH WEDNESDAY...WITH THE AXIS OF THE
HIGH SHIFTING SOUTHWARD ACROSS THE AREA ON THURSDAY AS A COLD
FRONT APPROACHES FROM THE NORTHWEST.
STRONG SUBSIDENCE AND A LACK OF DEEP MOISTURE WILL GENERALLY KEEP
RAIN-FREE CONDITIONS IN PLACE. THE EXCEPTION COULD BE ALONG PARTS OF
THE IMMEDIATE SOUTHEAST GEORGIA COAST WHERE ISOLATED CONVECTION
COULD DEVELOP OFFSHORE IN AN AREA OF ENHANCED LOW LEVEL CONVERGENCE
AND SHIFT ONSHORE AT TIMES TUESDAY NIGHT THROUGH THURSDAY.
HIGH TEMPERATURES WILL GENERALLY BE AROUND 90...WITH COOLER
TEMPERATURES ALONG THE IMMEDIATE COAST. RADIATIONAL COOLING WILL BE
SUFFICIENT TO ALLOW TEMPERATURES TO FALL INTO THE UPPER 60S AWAY
FROM THE COAST...WITH A FEW MID 60S POSSIBLE IN WELL SHELTERED
AND/OR LOW LYING AREAS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH THE LONG TERM
PERIOD. A LONGWAVE UPPER LEVEL TROUGH WILL BE THE PREDOMINANT
FEATURE OVER THE EASTERN U.S. THROUGH SATURDAY...BEFORE THE TROUGH
LIFTS OUT AND THE FLOW BECOMES MORE ZONAL LATE IN THE WEEKEND INTO
EARLY NEXT WEEK. AT THE SURFACE...A BACKDOOR COLD FRONT WILL DROP
ACROSS THE AREA FRIDAY INTO FRIDAY NIGHT...THEN STALL OUT JUST SOUTH
OF THE AREA THROUGH THE REMAINDER OF THE LONG TERM PERIOD AS MUCH
COOLER HIGH PRESSURE BUILDS IN FROM THE NORTH.
THERE IS A CHANCE THAT SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE
PASSAGE OF THE COLD FRONT FRIDAY AND FRIDAY NIGHT...AND CONTINUE
INTO SATURDAY ACROSS MUCH OF THE AREA AS THE FRONT STALLS JUST TO
THE SOUTH. PRECIPITATION CHANCES WILL THEN CONTINUE INTO EARLY NEXT
WEEK ACROSS MUCH OF SOUTHEAST GEORGIA WHICH IS IN CLOSER PROXIMITY
TO THE FRONT AND THE DEEPER MOISTURE...WITH SOMEWHAT DRIER
CONDITIONS POSSIBLE FARTHER NORTH INTO PARTS OF SOUTHEAST SOUTH
CAROLINA.
TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH FRIDAY...THEN
COOLER/BELOW TEMPERATURES WILL OCCUR DURING THE REMAINDER OF THE
LONG TERM PERIOD AS A NORTHEAST FLOW DEVELOPS AS HIGH PRESSURE
BUILDS SOUTHWARD INTO THE REGION.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS WITH A GREATER
THAN 30 PERCENT CONFIDENCE AT THIS TIME.
&&
.MARINE...
TODAY AND TONIGHT...HIGH PRESSURE WILL BUILD IN FROM THE NORTH
CAUSING WINDS TO SHIFT TO EASTERLY BUT REMAINING 15 KT OR LESS.
WINDS COULD BACK TO MORE NORTHEAST NEAR THE COAST LATE TONIGHT AS
A WEAK COASTAL TROUGH OF LOW PRESSURE TRIES TO DEVELOP. SIGNIFICANT WAVE
HEIGHTS WILL BE UP TO 3 FT WITHIN 20 NM AND UP TO 4 FT BEYOND 20
NM...DOMINATED BY A 8-9 SECOND E/SE SWELL...AT LEAST THROUGH
TODAY.
TUESDAY THROUGH SATURDAY...HIGH PRESSURE WILL BUILD OVER THE
REGION FROM THE NORTH THROUGH WEDNESDAY...MAINTAINING AN ONSHORE
FLOW OVER THE WATERS WITH WIND SPEEDS GENERALLY 15 KT OR LESS. THE
FLOW WILL BECOME MORE SOUTHERLY ON THURSDAY AHEAD OF AN APPROACHING
COLD FRONT...WHICH IS EXPECTED TO DROP ACROSS THE WATERS FRIDAY AND
FRIDAY NIGHT SHIFTING THE WINDS NORTHEAST IN ITS WAKE. A STRONG
NORTHEAST SURGE WILL THEN OCCUR FRIDAY NIGHT AND SATURDAY...LIKELY
RESULTING IN SMALL CRAFT ADVISORY CONDITIONS OVER PORTIONS OF THE
WATERS. SEAS WILL GENERALLY BE NO HIGHER THAN 2-4 FT...GREATEST OVER
THE OUTER GEORGIA WATERS...THROUGH FRIDAY BEFORE INCREASING A COUPLE
OF FEET SATURDAY AS THE STRONG NORTHEAST FLOW DEVELOPS AND THE FETCH
INCREASES.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS DES MOINES IA
353 PM CDT MON SEP 9 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 324 PM CDT MON SEP 9 2013
MAIN FORECAST CONCERN IS WITH WEAK FRONT EXPECTED TO DIP INTO FAR
NORTHERN IOWA OVERNIGHT TONIGHT. LATEST HOPWRF SUGGEST SOME WEAK
ISOLATED DEVELOPMENT ALONG THE FRONT PAST 05Z TUESDAY IN SOUTHERN
MINNESOTA AND NORTHWEST IOWA. THE HRRR AND 4.0 SPC WRF SUGGEST
SIMILAR TREND...ALTHOUGH SLIGHTLY FURTHER NORTHWEST. THERE IS SOME
WEAK FRONTOGENETICAL FORCING BETWEEN 850MB AND 700MB LATER TONIGHT
INTO EARLY TUESDAY MORNING THAT SNEAKS INTO NORTHWEST IOWA. SO
KEPT SLIGHT POPS GOING ACROSS THE NORTH TONIGHT...BUT HAVE LOW
CONFIDENCE WITH ANY SIGNIFICANT RAINFALL SINCE SHOWERS WILL BE
VERY HIGH BASED. WENT CLOSER TO THE ECMWF FOR LOW TEMPS TONIGHT
WITH THE WAA CONTINUING AHEAD OF THE FRONT.
.LONG TERM.../TUESDAY THROUGH MONDAY/...
ISSUED AT 324 PM CDT MON SEP 9 2013
MAIN FORECAST CONCERNS FOR TUESDAY INT WEDNESDAY REVOLVE AROUND A
COLD FRONTAL PASSAGE. MOST OF THE FORCING WITH THE FRONT SHIFTS
NORTH AND EAST OF THE AREA. WHILE DEEP SHEAR IS UNIMPRESSIVE THERE
IS SOME LOW LEVEL SHEAR COINCIDENT WITH THE FRONT. MODELS CONTINUE
TO SHOW LITTLE IN THE WAY OF RAINFALL AND THAT BEING POST FRONTAL.
THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL COME LATE
AFTERNOON AND EVENING WHEN A SHORT WAVE MOVES ACROSS MAINLY THE
NORTHERN FORECAST AREA AND INTERACTS WITH THE FRONT. SOUNDINGS
SHOW STEEP LAPSE RATES SO WHILE ANY STORMS WOULD BE ISOLATED TO
SCATTERED AT BEST THERE IS SOME POTENTIAL FOR AN ISOLATED WIND
THREAT. THE HEAT WILL STILL BE ON FOR SOUTHEAST PORTIONS OF THE
STATE TOMORROW AND THERE IS SOME CONCERN THAT WITH TWO WARM NIGHTS
NOW AND WHAT WILL BE THE SECOND HOT DAY THERE COULD BE SOME
CUMULATIVE EFFECTS OF PROLONGED HEAT. HOWEVER WITH LONGER NIGHTS
THERE SHOULD BE MORE TIME FOR THE BODY TO RECOVER SO WE WILL
CONTINUE TO HANDLE THE HEAT WITH A SPECIAL WEATHER STATEMENT.
THE FRONT GRADUALLY SHIFTS TO THE SOUTH THROUGH WEDNESDAY FOLLOWED
BY COOLER TEMPS FOR THE REST OF THE WEEK.
FOR THE WEEKEND THE MODELS SUGGEST A SHORTWAVE PUSHING ACROSS THE
NORTHERN PLAINS AGAIN AND POSSIBLY INTO THE UPPER MIDWEST. TIMING
AND STRENGTH OF THE SHORTWAVE ARE STILL IN QUESTION BUT THERE
APPEAR TO BE AT LEAST CHANCES FOR THUNDERSTORMS AND GRIDS CONTINUE
TO REFLECT THESE CHANCES.
&&
.AVIATION...09/18Z
ISSUED AT 1230 PM CDT MON SEP 9 2013
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE FORECAST PERIOD. MIXING
WILL CONTINUE TO INCREASE THIS AFTERNOON BEFORE WINDS DECOUPLE
BETWEEN 00-01Z TONIGHT. NOT ANTICIPATING ANY FOG TONIGHT AS WINDS
WILL REMAIN STRONG ENOUGH. MIXING LOOKS TO INCREASE AGAIN LATE
TOMORROW MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FAB/PODRAZIK
LONG TERM...FAB
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS GOODLAND KS
237 PM MDT MON SEP 9 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 237 PM MDT MON SEP 9 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
MOSTLY CLEAR WITH THE EXCEPTION OF SOME PATCHES OF DAYTIME CUMULUS.
TEMPERATURES HAVE RISEN INTO THE LOW 90S TO NEAR 100 IN A FEW SPOTS
ACROSS RED WILLOW...DECATUR...NORTON AND GRAHAM COUNTIES. WINDS WERE
GENERALLY FROM THE SOUTH AT 10 TO 20 MPH WITH GUSTS 25 TO 30 MPH.
DEWPOINTS WERE ON A SLOW DECLINE THIS AFTERNOON. A COLD FRONT WAS
LOCATED ACROSS NORTHEAST COLORADO AND SOUTHWEST NEBRASKA. AN AREA OF
LOW PRESSURE WAS DRAPED ACROSS THE AREA...STRETCHING FROM SOUTHWEST
NEBRASKA TO THE COLORADO FRONT RANGE. FIRE WEATHER HAS BECOME A
CONCERN THIS AFTERNOON AND WILL BE ADDRESSED IN A FIRE WEATHER
SECTION BELOW.
FOR THIS AFTERNOON AND TONIGHT...SURFACE CONVERGENCE IS PROJECTED TO
INCREASE ALONG THE COLD FRONT...ALLOWING SOME ISOLATED TO WIDELY
SCATTERED THUNDERSTORMS TO DEVELOP. IN ADDITION...CONVECTION
DEVELOPING OVER THE ROCKIES MAY ORGANIZE AND MOVE EAST INTO THE
REGION FROM THE LATEST RUNS OF THE HRRR MODEL. MOST OTHER MODELS
HOLD ALL PRECIPITATION OFF AND KEEP IT TO THE NORTHWEST OF THE
FORECAST AREA. A STRONG STORM OR TWO IS POSSIBLE WITH DAMAGING
WINDS AND SMALL HAIL AS THE MAIN THREAT. HOWEVER...INSTABILITY IS
NOT AS HIGH AS NEEDED FOR A MORE WIDESPREAD THREAT OF SEVERE
WEATHER. THE FRONT SHOULD MOVE TO THE SOUTH DURING THE OVERNIGHT
HOURS...BRINGING COOLER TEMPERATURES...MORE MOISTURE TO THE AIR
AND A WIND SHIFT. LOW TEMPERATURES WILL VARY ACROSS THE REGION
WITH LOW 60S ACROSS EAST COLORADO AND MID 60S TO NEAR 70 FOR THE
REST OF THE AREA.
FOR TOMORROW...THE COLD FRONT IS EXPECTED TO STALL ACROSS THE AREA.
IN ADDITION TO THE FRONT...AN UPPER LEVEL DISTURBANCE WILL APPROACH
FROM THE WEST...PROVIDING EXTRA LIFT FOR SHOWER AND THUNDERSTORM
DEVELOPMENT. CHANCES FOR PRECIPITATION WILL BE MUCH HIGHER DURING
THE LATE AFTERNOON TO EVENING HOURS FOR A LARGER AREA. TEMPERATURES
BEHIND THE FRONT WILL BE NOTICEABLY COOLER WITH HIGHS IN THE UPPER
70S TO LOW 80S. ALONG AND AHEAD OF THE FRONT...TEMPERATURES WILL BE
WARM WITH HIGHS IN THE MID 80S TO LOW 90S WHERE DAYTIME HEATING
LASTS LONGER BEFORE CLOUDS AND CONVECTIVE ACTIVITY DEVELOPS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 1249 PM MDT MON SEP 9 2013
PATTERN CHANGE WILL OCCUR DURING THIS PERIOD AS THE UPPER RIDGE
WHICH HAS BEEN DOMINANT WILL SHIFT TO THE SOUTHEASTERN CONUS AND
TROUGH WHICH HAS BEEN OVER THE WEST WILL MOVE TO THE CENTRAL AND
NORTHERN ROCKIES. THIS WILL BRING NEAR TO BELOW NORMAL
TEMPERATURES AND OCCASIONAL CHANCES FOR PRECIPITATION TO THE AREA.
FIRST CHANCE FOR RAIN WILL OCCUR TUESDAY NIGHT WITH SHORTWAVE
TROUGH MOVING UP IN THE SOUTHWEST FLOW ALOFT. ANOTHER SHORTWAVE IS
FORECAST ON THURSDAY. BOTH SYSTEMS WILL HAVE PLENTIFUL MOISTURE TO
WORK WITH A TROPICAL CONNECTION TO THE BAJA. RAIN CHANCES CONTINUE
THROUGH THE WEEKEND AS THE UPPER LOW OPENS UP AND EVENTUALLY GETS
ENTRAINED IN THE NORTHERN STREAM. LATE IN THE PERIOD AN UPPER RIDGE
WILL BEGIN TO REBUILD BEHIND THE DEPARTING SYSTEM SIGNALING THE
RETURN OF WARM AND DRY CONDITIONS EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1127 AM MDT MON SEP 9 2013
VFR CONDITIONS CAN BE EXPECTED FOR THE NEXT 24 HOURS. A COLD FRONT
WAS MAKING ITS WAY TO THE SOUTH AND WILL BEGIN AFFECTING THE TAF
SITES TONIGHT. WITH THE FRONT DRAPED SOMEWHERE ACROSS THE
AREA...WIND DIRECTIONS WILL VARY THROUGHOUT THE NIGHT SO CONFIDENCE
IN THE WINDS IS LOWER THAN NORMAL. WIND SPEEDS TONIGHT SHOULD BE
LIGHT ONCE DAYTIME GUSTS ARE LOST THIS EVENING. A FEW ISOLATED
THUNDERSTORMS MAY DEVELOP ALONG THE FRONT THIS AFTERNOON AND
EVENING. HOWEVER...CONFIDENCE THAT CONVECTION WOULD BE CLOSE
TO TAF SITES WAS TOO LOW TO EVEN WARRANT A VCTS MENTION IN TAFS.
MOST OF THE THUNDERSTORM ACTIVITY SHOULD BE NORTHWEST OF TAF SITES.
&&
.FIRE WEATHER...
ISSUED AT 237 PM MDT MON SEP 9 2013
NEAR CRITICAL FIRE WEATHER CONDITIONS HAVE DEVELOPED ACROSS PORTIONS
OF THE REGION THIS AFTERNOON. HOT TEMPERATURES AND LOW DEWPOINTS
HAVE LEAD TO RELATIVE HUMIDITIES DROPPING OFF INTO THE 15-25 PERCENT
RANGE. WINDS HAVE BEEN GUSTY AND A FEW LOCATIONS WERE BARELY MEETING
CRITERIA. HOWEVER...WHETHER OR NOT THE CONDITIONS WOULD LAST THE
FULL THREE HOURS TO MEET WARNING CRITERIA HAS BEEN PROBLEMATIC AS
THE WINDS HAVE BEEN BOUNCING UP AND DOWN THIS AFTERNOON. IN
ADDITION...A SLIGHT RISE IN DEWPOINTS FROM SOUTH TO NORTH HAS BEEN
NOTED AS A MORE MOIST AIRMASS ADVECTS IN FROM THE SOUTH. AS A
RESULT...CONFIDENCE WAS NOT QUITE HIGH ENOUGH TO GO AHEAD AND
ISSUE A RED FLAG WARNING FOR REDWILLOW...HITCHCOCK...DECATUR...
HOXIE...SHERIDAN...THOMAS....ST FRANCIS AND SHERMAN COUNTIES. IF
IT BECOMES APPARENT THAT WINDS WILL STAY UP...A SHORT DURATION RED
FLAG WARNING MAY BE REQUIRED. WILL UPDATE THE FIRE WEATHER
FORECAST TO REFLECT THE LATEST TRENDS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...024
AVIATION...RRH
FIRE WEATHER...RRH
AREA FORECAST DISCUSSION
NWS JACKSON KY
553 PM EDT MON SEP 9 2013
.UPDATE...
ISSUED AT 553 PM EDT MON SEP 9 2013
A FEW SHOWERS AND THUNDERSTORMS HAVE DEVELOPED NORTHWARD INTO SOUTH
CENTRAL KENTUCKY...BASICALLY EASTERN WAYNE COUNTY/MCCREARY
COUNTY...NORTH INTO EASTERN PULASKI COUNTY. BASED ON SATELLITE...THIS
ACTIVITY SHOULD REMAIN CONFINED TO THESE AREAS OVER THE NEXT HOUR OR
TWO BEFORE WEAKENING AND DISSIPATING AS THE SUN GOES DOWN. THIS
SHOULD ALLOW ACTIVITY TO DIE OFF BY ROUGHLY 00Z. UPDATED NDFD GRIDS
TO REFINE THE POPS...BUT WILL NOT ISSUE A NEW ZFP WITH THE ISOLATED
NATURE OF THIS ACTIVITY.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 340 PM EDT MON SEP 9 2013
18Z SFC ANALYSIS SHOWS WEAK HIGH PRESSURE IN PLACE OVER EAST KENTUCKY
WITH LOW PRESSURE FOUND OFF TO THE NORTHWEST. A DOME OF HIGHER
HEIGHTS IS BUILDING OVER THE REGION AND THIS HAS HELPED TO CONTRIBUTE
TO A VERY WARM LATE SUMMER DAY ACROSS EAST KENTUCKY WITH TEMPS
APPROACHING 90 DEGREES. PRETTY HIGH DEWPOINTS IN THE MID AND UPPER
60S ARE MAKING IT FEEL EVEN WARMER...IN ADDITION TO PROVIDING AN
UNCOMFORTABLE HUMIDITY LEVEL. HERE AT PEAK HEATING...A FEW OF THE CU
HAVE MANAGED TO GET DEEP ENOUGH THAT A SHOWER OR THUNDERSTORM WILL
BE POSSIBLE...MAINLY ALONG OUR SOUTHERN AND EASTERN BORDERS.
OTHERWISE...SKIES ARE MOSTLY CLEAR AND THE CU SHALLOW.
THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM
DEPICTING A MODERATELY STRONG RIDGE PUSHING INTO THE LOWER OHIO
VALLEY AND ACROSS TO THE MID ATLANTIC COAST. THIS RIDGE WILL NOT BE
COMPLETELY FREE OF ENERGY OR PROHIBITIVELY WARM AT MID LEVELS...
THOUGH...SO ITS ABILITY TO PUT A CAP ON CONVECTION WILL BE LIMITED.
IN THIS KIND OF ENVIRONMENT...THE MESOSCALE WILL DOMINATE FOR WEATHER
SPECIFICS SO HAVE FAVORED A MORE SUBDUED VERSION OF THE NAM12 WITH
INPUT FROM THE HRRR IN THE NEAR TERM. ALSO FAVORED AN ENHANCED
DIURNAL TRACE FOR POPS.
SENSIBLE WEATHER WILL FEATURE MORE IN THE WAY OF PERSISTENCE THROUGH
WEDNESDAY MORNING. AT NIGHT...WE CAN EXPECT A FADE OUT OF THE
DAYTIME CLOUDS AND PATCHY FOG...LOCALLY DENSE IN THE VALLEYS...
DEVELOPING BY DAWN. HIGH DEWPOINTS WILL KEEP THERE FROM BEING MUCH OF
A RIDGE TO VALLEY TEMP SPLIT BOTH TONIGHT AND TUESDAY NIGHT. FOR THE
DAY TUESDAY...IT WILL BE ANOTHER WARM AND HUMID ONE WITH A SMALL
CHANCE OF SHOWERS AND THUNDERSTORMS DEVELOPING WITH PEAK HEATING...
DESPITE THE RIDGING ALOFT.
JUMP STARTED THE TD AND WIND GRIDS WITH CONSSHORT DATA THROUGH 12Z
TUESDAY AND THE CONSALL THEREAFTER. FOR TEMPERATURES...PREFERRED THE
OBS DATABASE AS A GUIDE FOR THE DIURNAL CURVE AND MODIFIED CONSALL
FOR MAX AND MIN TEMPS...TEMPERING THE TOO WARM GRIDDED MOS HIGHS ON
TUESDAY WITH SOME RAW MODEL OUTPUT. AS FOR POPS...ENDED UP PRETTY
CLOSE TO AN AVERAGE OF THE GUIDANCE THROUGH THE SHORT TERM PERIOD.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 245 PM EDT MON SEP 9 2013
THE MODELS ALL AGREE THAT WEDNESDAY AND THURSDAY WILL BE THE ACTIVE
DAYS OF THE EXTENDED PERIOD. A SERIES OF WEATHER SYSTEMS...BOTH
SURFACE FRONTS AND TROUGHS OF LOW PRESSURE ALOFT...WILL BRING
SHOWERS AND THUNDERSTORMS TO EASTERN KENTUCKY DURING THE MIDDLE OF
THE WEEK. THE MORE POTENT WEATHER MAKER WILL BE A SIGNIFICANT COLD
FRONT THAT IS EXPECTED TO MOVE ACROSS THE AREA THURSDAY INTO
THURSDAY EVENING. THE FRONT WILL LIKELY BE SLOWED UP A BIT BY THE
HIGH TERRAIN OF EAST KENTUCKY FOR IT FINALLY EXITS THE AREA THURSDAY
EVENING. ONCE THE FRONT IS OUT OF THE AREA...A LARGE AND WELL
DEFINED AREA OF HIGH PRESSURE WILL MIGRATE SOUTHWARD OUT OF CANADA
AND THEN THE OHIO VALLEY...BEFORE FINALLY SETTLING OVER THE EASTERN
CONUS FROM FRIDAY ONWARD. THE AIR MASS ASSOCIATED WITH THIS RIDGE
WILL BRING VERY UNSEASONABLY COOL TEMPERATURES TO THE REGION FRIDAY
AND SATURDAY. HIGHS ON FRIDAY AND SATURDAY WILL ONLY BE TOPPING OUT
IN THE LOW TO MID 70S...BEFORE REBOUNDING A BIT ON SUNDAY...WHEN
HIGHS IN THE UPPER 70S TO AROUND 80 ARE EXPECTED. THE
GFS...ECMWF...AND NAEFS MODELS ALL BEGIN THE PERIOD WITH A LARGE
TROUGH OF LOW PRESSURE ALOFT ACROSS THE EASTERN CONUS...WITH A
STRONG RIDGE OF HIGH PRESSURE SETTING UP OUT WEST. THE MIDDLE OF THE
WEEK WILL FEATURE WARM AND WET WEATHER...WHILE THE END OF THE WEEK
AND THE UPCOMING WEEKEND WILL BE VERY COOL AND DRY AND FALL LIKE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 150 PM EDT MON SEP 9 2013
VFR CONDITIONS WILL DOMINATE UNTIL 6-8Z TONIGHT WHEN FOG IS ONCE
AGAIN EXPECTED TO FORM. CANNOT COMPLETELY RULE OUT SOME LOWER CIGS OR
VIS SHOULD A STRAY SHOWER OR STORM POP UP NEAR A TAF SITE THIS
AFTERNOON...BUT THE CHANCES ARE PRETTY LOW. THE FOG WILL BURN OFF
TOMORROW MORNING WITH A SIMILAR TYPE OF DAY AND LOW CONVECTIVE
CHANCES AS WE HAVE TODAY. WINDS THROUGHOUT THE PERIOD WILL BE LIGHT
AND VARIABLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
340 PM EDT MON SEP 9 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 340 PM EDT MON SEP 9 2013
18Z SFC ANALYSIS SHOWS WEAK HIGH PRESSURE IN PLACE OVER EAST KENTUCKY
WITH LOW PRESSURE FOUND OFF TO THE NORTHWEST. A DOME OF HIGHER
HEIGHTS IS BUILDING OVER THE REGION AND THIS HAS HELPED TO CONTRIBUTE
TO A VERY WARM LATE SUMMER DAY ACROSS EAST KENTUCKY WITH TEMPS
APPROACHING 90 DEGREES. PRETTY HIGH DEWPOINTS IN THE MID AND UPPER
60S ARE MAKING IT FEEL EVEN WARMER...IN ADDITION TO PROVIDING AN
UNCOMFORTABLE HUMIDITY LEVEL. HERE AT PEAK HEATING...A FEW OF THE CU
HAVE MANAGED TO GET DEEP ENOUGH THAT A SHOWER OR THUNDERSTORM WILL
BE POSSIBLE...MAINLY ALONG OUR SOUTHERN AND EASTERN BORDERS.
OTHERWISE...SKIES ARE MOSTLY CLEAR AND THE CU SHALLOW.
THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM
DEPICTING A MODERATELY STRONG RIDGE PUSHING INTO THE LOWER OHIO
VALLEY AND ACROSS TO THE MID ATLANTIC COAST. THIS RIDGE WILL NOT BE
COMPLETELY FREE OF ENERGY OR PROHIBITIVELY WARM AT MID LEVELS...
THOUGH...SO ITS ABILITY TO PUT A CAP ON CONVECTION WILL BE LIMITED.
IN THIS KIND OF ENVIRONMENT...THE MESOSCALE WILL DOMINATE FOR WEATHER
SPECIFICS SO HAVE FAVORED A MORE SUBDUED VERSION OF THE NAM12 WITH
INPUT FROM THE HRRR IN THE NEAR TERM. ALSO FAVORED AN ENHANCED
DIURNAL TRACE FOR POPS.
SENSIBLE WEATHER WILL FEATURE MORE IN THE WAY OF PERSISTENCE THROUGH
WEDNESDAY MORNING. AT NIGHT...WE CAN EXPECT A FADE OUT OF THE
DAYTIME CLOUDS AND PATCHY FOG...LOCALLY DENSE IN THE VALLEYS...
DEVELOPING BY DAWN. HIGH DEWPOINTS WILL KEEP THERE FROM BEING MUCH OF
A RIDGE TO VALLEY TEMP SPLIT BOTH TONIGHT AND TUESDAY NIGHT. FOR THE
DAY TUESDAY...IT WILL BE ANOTHER WARM AND HUMID ONE WITH A SMALL
CHANCE OF SHOWERS AND THUNDERSTORMS DEVELOPING WITH PEAK HEATING...
DESPITE THE RIDGING ALOFT.
JUMP STARTED THE TD AND WIND GRIDS WITH CONSSHORT DATA THROUGH 12Z
TUESDAY AND THE CONSALL THEREAFTER. FOR TEMPERATURES...PREFERRED THE
OBS DATABASE AS A GUIDE FOR THE DIURNAL CURVE AND MODIFIED CONSALL
FOR MAX AND MIN TEMPS...TEMPERING THE TOO WARM GRIDDED MOS HIGHS ON
TUESDAY WITH SOME RAW MODEL OUTPUT. AS FOR POPS...ENDED UP PRETTY
CLOSE TO AN AVERAGE OF THE GUIDANCE THROUGH THE SHORT TERM PERIOD.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 245 PM EDT MON SEP 9 2013
THE MODELS ALL AGREE THAT WEDNESDAY AND THURSDAY WILL BE THE ACTIVE
DAYS OF THE EXTENDED PERIOD. A SERIES OF WEATHER SYSTEMS...BOTH
SURFACE FRONTS AND TROUGHS OF LOW PRESSURE ALOFT...WILL BRING
SHOWERS AND THUNDERSTORMS TO EASTERN KENTUCKY DURING THE MIDDLE OF
THE WEEK. THE MORE POTENT WEATHER MAKER WILL BE A SIGNIFICANT COLD
FRONT THAT IS EXPECTED TO MOVE ACROSS THE AREA THURSDAY INTO
THURSDAY EVENING. THE FRONT WILL LIKELY BE SLOWED UP A BIT BY THE
HIGH TERRAIN OF EAST KENTUCKY FOR IT FINALLY EXITS THE AREA THURSDAY
EVENING. ONCE THE FRONT IS OUT OF THE AREA...A LARGE AND WELL
DEFINED AREA OF HIGH PRESSURE WILL MIGRATE SOUTHWARD OUT OF CANADA
AND THEN THE OHIO VALLEY...BEFORE FINALLY SETTLING OVER THE EASTERN
CONUS FROM FRIDAY ONWARD. THE AIR MASS ASSOCIATED WITH THIS RIDGE
WILL BRING VERY UNSEASONABLY COOL TEMPERATURES TO THE REGION FRIDAY
AND SATURDAY. HIGHS ON FRIDAY AND SATURDAY WILL ONLY BE TOPPING OUT
IN THE LOW TO MID 70S...BEFORE REBOUNDING A BIT ON SUNDAY...WHEN
HIGHS IN THE UPPER 70S TO AROUND 80 ARE EXPECTED. THE
GFS...ECMWF...AND NAEFS MODELS ALL BEGIN THE PERIOD WITH A LARGE
TROUGH OF LOW PRESSURE ALOFT ACROSS THE EASTERN CONUS...WITH A
STRONG RIDGE OF HIGH PRESSURE SETTING UP OUT WEST. THE MIDDLE OF THE
WEEK WILL FEATURE WARM AND WET WEATHER...WHILE THE END OF THE WEEK
AND THE UPCOMING WEEKEND WILL BE VERY COOL AND DRY AND FALL LIKE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 150 PM EDT MON SEP 9 2013
VFR CONDITIONS WILL DOMINATE UNTIL 6-8Z TONIGHT WHEN FOG IS ONCE
AGAIN EXPECTED TO FORM. CANNOT COMPLETELY RULE OUT SOME LOWER CIGS OR
VIS SHOULD A STRAY SHOWER OR STORM POP UP NEAR A TAF SITE THIS
AFTERNOON...BUT THE CHANCES ARE PRETTY LOW. THE FOG WILL BURN OFF
TOMORROW MORNING WITH A SIMILAR TYPE OF DAY AND LOW CONVECTIVE
CHANCES AS WE HAVE TODAY. WINDS THROUGHOUT THE PERIOD WILL BE LIGHT
AND VARIABLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
150 PM EDT MON SEP 9 2013
.UPDATE...
ISSUED AT 145 PM EDT MON SEP 9 2013
UPDATED THE GRIDS TO FINE TUNE MAX TEMPS AND HOURLY CURVES FOR T AND
TD THROUGH EVENING. ALSO TOUCHED UP THE SKY COVER AND POP GRIDS PER
THE LATEST OBS AND TRENDS. BETTER CU DEVELOPMENT IS LOCATED OVER THE
HIGHER TERRAIN IN THE SOUTHEAST AND ALSO WEST OF INTERSTATE 75...SOUTH
AND INTO TENNESSEE. THE HRRR SHOWS SOME LIMITED DEVELOPMENT LATE THIS
AFTERNOON OVER THAT FIRST AREA OF MORE ENHANCED CU...SO WOULD NOT
RULE CONVECTION OUT COMPLETELY. MEANWHILE...THE NAM12 SHOWS SOME MORE
SUBSTANTIAL DEVELOPMENT THIS AFTERNOON ACROSS THE CUMBERLAND VALLEY.
AM NOT SEEING MUCH SUPPORT FOR THIS...THOUGH...SO HAVE DISCOUNTED IT
BUT...WILL KEEP POPS IN THE 10 TO 15 PERCENT THROUGH THIS AREA AND
POINTS EAST DURING THE REMAINDER OF THE AFTERNOON. UPDATES HAVE BEEN
SENT TO THE NDFD AND WEB SERVERS.
UPDATE ISSUED AT 1045 AM EDT MON SEP 9 2013
14Z SFC ANALYSIS SHOWS WEAK HIGH PRESSURE OVER EAST KENTUCKY AS THE
EARLIER FRONT HAS DISSIPATED. WITH RIDGING BUILDING IN ALOFT...EXPECT
CONVECTION TO BE SUPPRESSED TODAY...BUT WILL HAVE TO WATCH THE HIGHER
TERRAIN NEAR THE VIRGINIA BORDER AS THE ONE PLACE THAT MAY BE THE
EXCEPTION. CURRENTLY...ALL IS QUIET ACROSS EAST KENTUCKY AS THE EARLY
MORNING FOG HAS BURNED OFF AND SKIES ARE MOSTLY CLEAR. TEMPERATURES
ARE RESPONDING NICELY TO THE SUNSHINE WITH READINGS CLIMBING INTO THE
MID 70S IN MOST LOCATIONS...THOUGH THIS RISE IS A BIT DELAYED IN THE
PLACES WHERE THE FOG JUST RECENTLY CLEARED. MEANWHILE...DEWPOINTS
REMAIN ON THE HIGH AND UNCOMFORTABLE SIDE...GENERALLY IN THE MID TO
UPPER 60S. THE FORECAST IS ON TRACK SO HAVE UPDATED THE ZONES TO
REMOVE THE MORNING FOG WORDING AND ADJUSTED THE SKY...T...AND TD
GRIDS PER THE LATEST OBSERVATIONS AND TRENDS. THESE GRIDS HAVE BEEN
SENT THE THE NDFD AND WEB SERVES.
UPDATE ISSUED AT 730 AM EDT MON SEP 9 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. ONLY HAD TO MAKE SOME MINOR ADJUSTMENTS TO TEMPERATURES AND
DEWPOINTS FOR THE FIRST FEW HOURS OF THE FORECAST. THE REST OF THE
FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 308 AM EDT MON SEP 9 2013
THE MODELS ARE IN GOOD AGREEMENT WITH THE UPPER AIR AND SURFACE
PATTERNS...BUT THEY DIFFER ON WHETHER OR NOT THAT THIS PATTER WILL BE
ABLE TO PRODUCE ANY SHOWERS OR THUNDERSTORMS. THE GFS IS THE DRIEST
OF THE MODELS AND IT ALSO INITIALIZES THE BEST. SO DECIDED TO GO WITH
THE GFS AS THE MODEL OF THE DAY AND HAVE TAKEN OUT ANY PRECIPITATION
FOR TODAY ALONG THE VIRGINIA BORDER. FOR TUESDAY...LEFT SOME ISOLATED
THUNDERSTORMS IN THE FORECAST...HOWEVER CONFIDENCE IN GETTING THEM IS
PRETTY LOW. THE ATMOSPHERE WILL CERTAINLY BE UNSTABLE ENOUGH ON
TUESDAY...THE THING THAT IS MISSING IS THE TRIGGER TO GET SOME STORMS
GOING. FOR TEMPERATURES...JUST NUDGED THEM TOWARD THE MODEL BLEND. IF
NO STORMS DEVELOP ON TUESDAY...THEN THE TEMPERATURES COULD ACTUALLY
GET A LITTLE LOWER.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 402 AM EDT MON SEP 9 2013
THE MODELS REMAIN IN GENERAL AGREEMENT WITH THE LONG WAVE PATTERN
THROUGH THE PERIOD...WITH AN UPPER LEVEL RIDGE POISED FROM THE MID-
ATLANTIC STATES THROUGH THE TENNESSEE VALLEY. FASTER FLOW ACROSS THE
NORTHERN PLAINS WILL ESCORT IN A DEEPENING SHORT WAVE TROUGH THAT
WILL SWING THROUGH THE GREAT LAKES AND NORTHERN OHIO VALLEY THROUGH
THURSDAY...SHUNTING AND WEAKENING THE RIDGE BACK TOWARDS THE PLAINS.
THIS WILL ALLOW A COLD FRONT TO DROP SOUTHEAST INTO THE TENNESSEE
VALLEY BY FRIDAY...BRINGING AN END TO THE HEAT AND HUMIDITY.
TROUGHING WILL THEN LINGER ACROSS NEW ENGLAND THROUGH THE FIRST PART
OF THE WEEKEND...BEFORE THE NEXT DEEPER SHORT WAVE TROUGH MOVES
ACROSS THE NORTHERN GREAT LAKES. THIS WILL HELP FLATTEN OUT THE FLOW
OUT AHEAD OF IT AND ALLOW FOR AT LEAST SOME MODEST RIDGING TO BUILD
BACK INTO THE LOWER MISSISSIPPI VALLEY THROUGH THE END OF THE WEEK.
ISOLATED TO SCATTERED CONVECTION WILL POP UP ACROSS EASTERN KENTUCKY
THROUGH WEDNESDAY...AS THE UPPER LEVEL RIDGE BEGINS TO BREAK DOWN AND
PLENTY OF HEAT AND HUMIDITY LINGER. THE BEST CHANCE OF PRECIPITATION
CONTINUES TO BE CENTERED AROUND THURSDAY AS THE FRONT APPROACHES AND
EVENTUALLY MOVES THROUGH THE AREA BY THURSDAY EVENING. BY FRIDAY...AN
AREA OF SURFACE HIGH PRESSURE WILL BE BUILDING IN FROM THE
NORTH...BRINGING DRY WEATHER AND A WELCOMED RELIEF FROM THE HUMIDITY.
HIGHS IN THE MID TO UPPER 80S THROUGH THURSDAY WILL DROP BACK DOWN
INTO THE 70S FOR THE WEEKEND...WITH LOWS MAINLY IN THE 50S...ALTHOUGH
SOME OF THE MORE SHELTERED VALLEYS MAY SEE 40S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 150 PM EDT MON SEP 9 2013
VFR CONDITIONS WILL DOMINATE UNTIL 6-8Z TONIGHT WHEN FOG IS ONCE
AGAIN EXPECTED TO FORM. CANNOT COMPLETELY RULE OUT SOME LOWER CIGS OR
VIS SHOULD A STRAY SHOWER OR STORM POP UP NEAR A TAF SITE THIS
AFTERNOON...BUT THE CHANCES ARE PRETTY LOW. THE FOG WILL BURN OFF
TOMORROW MORNING WITH A SIMILAR TYPE OF DAY AND LOW CONVECTIVE
CHANCES AS WE HAVE TODAY. WINDS THROUGHOUT THE PERIOD WILL BE LIGHT
AND VARIABLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...JJ
LONG TERM...GEOGERIAN
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
303 PM EDT MON SEP 9 2013
.SYNOPSIS...
HEAT AND HUMIDITY WILL BUILD THIS WEEK BEFORE A STRONG COLD FRONT
ON THURSDAY USHERS IN MUCH COOLER TEMPERATURES.
&&
.NEAR TERM /THROUGH TUESDAY/...
QUICK UPDATE MADE TO ACCOUNT FOR CURRENT SHWRS/TSTMS SLGTLY
EARLIER THAN IN GOING FCST. PREV DISCUSSION FOLLOWS...
A WARM FRONT IS STILL PROGGED TO LIFT NORTH ACROSS THE REGION
LATER THIS AFTERNOON BUT QUESTION REMAINS ON HOW MUCH CONVECTION
WE WILL SEE WITH IT. DEWPOINTS HAVE ALREADY BEGUN TO REBOUND INTO
THE MID 60S OVER EASTERN OHIO AND NORTHERN WEST VIRGINIA BUT
INSTABILITY REMAINS ELEVATED PER THE MOST RECENT MESOANALYSIS.
STILL THINK THAT...WITH THE HELP OF A PASSING UPPER- LEVEL
SHORTWAVE THAT HAS SUPPORTED SOME SHOWERS AND STORMS OVER
MICHIGAN...THERE COULD BE AT LEAST SCATTERED SHOWERS AND STORMS
OVER OUR REGION TODAY. WHILE THERE ARE A FEW DIFFERENCES IN THE
DETERMINISTIC SOLUTIONS...THE RAP AND HRRR SEEM TO SUGGEST THAT
THE NORTHERN ZONES MAY HAVE THE BEST CHANCE FOR PRECIP. WITH THIS
IN MIND...KEPT THE CHANCE POPS FOCUSED IN THIS AREA AND CONTINUED
A SLIGHT CHANCE EVERYWHERE ELSE. OF COURSE...THIS DOES NOT
COMPLETELY RULE OUT THE CHANCE FOR THUNDERSTORMS FARTHER
SOUTH...SINCE THOSE COUNTIES ARE EXPERIENCING MORE-RAPID SURFACE
HEATING DUE TO LESS CLOUD COVER.
HIGH PRESSURE WILL BUILD EASTWARD TONIGHT...AND WITH IT WILL RETURN
VERY WARM AND MUGGY WEATHER. HIGHS ARE FORECAST TO BE WELL ABOVE
SEASONAL AVERAGES TOMORROW...WITH MOST PLACES SEEING MID 80S TO
EVEN 90. WHILE THIS COULD LEAD TO PLENTY OF SURFACE
INSTABILITY...THERE DOES NOT SEEM TO BE ANY FOCUS FOR CONVECTION.
THE ONLY CONSIDERATION IS THE HIGHER ELEVATIONS...WHERE A FEW
THUNDERSTORMS COULD DEVELOP WITH THE HELP OF OROGRAPHIC LIFT. AT
THIS TIME THOUGH...MAINTAINED A DRY FORECAST FOR ALL OF TUESDAY.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
A VERY MOIST AND UNSTABLE AMS WILL RMN IN PLACE THRU THU OWING TO
PERSISTENT SWLY LOW-LVL FLOW. TUE NGT AND WED NGT WILL BOTH SEE
MINIMA IN THE 60S...WITH MINIMA APRCHG 70 TUE NGT.
SHWRS AND TSTMS WILL INCR IN CVRG ON WED AS A LOW-AMPLITUDE SHRTWV
TROF APRCHS AND UPR RDG FLATTENS. CLD CVR XPCD TO BE SUBSTANTIAL
OWING TO UNSTABLE AMS...WHICH MAY LMT MAXIMA SLGTLY COMPARED TO
TUE. HOWEVER...MAXIMA STILL XPCD TO REACH MID-UPR 80S.
LACK OF STRONG MID-LVL FLOW ON WED WILL YIELD RATHER ANEMIC SHEAR
DESPITE MDT INSTBY. WITH PWATS FCSTD IN EXCESS OF 1.8 IN...MAIN
CONCERN WILL BE FOR FLOODING FROM SLOW-MOVG TSTMS PRODUCING VERY
HVY RAIN.
BECAUSE THE FLY ALWAYS FINDS ITS OINTMENT...THE 12Z/09 NAM12 HAS
OFFERED A MUCH SLOWER ARRRIVAL OF THE CDFNT THAT WAS XPCD TO
ARRIVE ON THU. GFS/ECMWF STILL AGREE ON A MID-LATE DAY FROPA WHILE
NAM SUGGESTS AN ARRIVAL OVNGT THU NGT.
GIVEN CONSISTENCY OF GFS ENSEMBLE WITH GFS/ECMWF SOLUTIONS...THE
NAM12 SOLUTION WILL BE DEEMED AN OUTLIER...AND FCST TIMING WILL BE
MAINTAINED WITH FROPA DURG THU. WITH FAVORABLE TIMING OF FROPA AND
MINIMAL OVNGT CNVCTN XPCD...THU APPEARS QUITE FAVORABLE FOR WDSPRD
TSTMS ALONG THE ADVCG BNDRY. THUS...POPS WERE INCRD TO LKLY AS THE
BNDRY CROSSES AND MAXIMA WERE INCRD SLGTLY FOLLOWING THE TREND OF
LATEST GUIDANCE.
GUIDANCE ALSO SUGGESTS POST-FRONTAL CLDS WILL INVADE THU NGT AHD
OF SECONDARY PRES SURGE. CLD CVR WAS INCRD SGFNTLY LATE THU NGT...
WHICH WILL SLOW THE XPCD COOLING. THUS...THU NGT MINIMA WERE INCRD
A FEW DEG F.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A STG CDFNT WL CROSS THE RGN THU CONTG THE SHWR/TSTM CHCS. HIGH
PRES IS THEN EXPD TO BLD IN THRU THE WKEND. AFT FROPA...850MB
TEMPS DROP INTO THE SINGLE DIGITS...BOTTOMING OUT ARND 2 DEG C FRI
NGT. THIS WL BRING WELL BLO AVG TEMP FRI THRU SUN...ALTHOUGH SOME
MODERATION CAN BE EXPD SUN AS THE FLOW TURNS SRLY AND THE HIGH
SHIFTS EWD.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
GENERAL VFR IS EXPECTED TO CONTINUE THROUGH MUCH OF THE PERIOD. A
LIFTING WARM FRONT WILL STILL PROVIDE THE CHANCE FOR SHOWERS AND
THUNDERSTORMS THIS AFTERNOON BUT AT THIS POINT COVERAGE IS
EXPECTED TO REMAIN SMALL. WILL MENTION VCTS IN THE SITES NORTH OF
PIT WHERE THE MODEL GUIDANCE CONTINUES TO SUGGEST THE GREATEST
PROBABILITY AND WILL MAINTAIN SCATTERED/BROKEN MID DECK EVERYWHERE
ELSE. ONE THING TO NOTE IS ANY TAF SITE THAT DOES EXPERIENCE A
SHOWER OR STORM WILL LIKELY EXPERIENCE IFR VISIBILITIES WITH
INCREASING LOW LEVEL MOISTURE.
WIND WILL GRADUALLY SHIFT TO SOUTHWESTERLY THROUGH THE AFTERNOON.
HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT...ENDING THE THREAT FOR
PRECIPITATION. WITH THE LOW LEVELS REMAINING MOIST...DO ANTICIPATE
SOME FOG IN SPOTS BUT LINGERING CLOUDS AND ELEVATED WIND MAY KEEP
IT MINIMAL.
.OUTLOOK.../MONDAY NIGHT THROUGH SATURDAY/...
GENERAL VFR IS EXPECTED UNTIL A COLD FRONT APPROACHES FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
UPDATE...KRAMAR
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
157 PM EDT MON SEP 9 2013
.SYNOPSIS...
HEAT AND HUMIDITY WILL BUILD THIS WEEK BEFORE A STRONG COLD FRONT
ON THURSDAY USHERS IN MUCH COOLER TEMPERATURES.
&&
.NEAR TERM /THROUGH TUESDAY/...
A WARM FRONT IS STILL PROGGED TO LIFT NORTH ACROSS THE REGION
LATER THIS AFTERNOON BUT QUESTION REMAINS ON HOW MUCH CONVECTION WE
WILL SEE WITH IT. DEWPOINTS HAVE ALREADY BEGUN TO REBOUND INTO THE
MID 60S OVER EASTERN OHIO AND NORTHERN WEST VIRGINIA BUT INSTABILITY
REMAINS ELEVATED PER THE MOST RECENT MESOANALYSIS. STILL THINK
THAT...WITH THE HELP OF A PASSING UPPER-LEVEL SHORTWAVE THAT HAS
SUPPORTED SOME SHOWERS AND STORMS OVER MICHIGAN...THERE COULD BE
AT LEAST SCATTERED SHOWERS AND STORMS OVER OUR REGION TODAY. WHILE
THERE ARE A FEW DIFFERENCES IN THE DETERMINISTIC SOLUTIONS...THE
RAP AND HRRR SEEM TO SUGGEST THAT THE NORTHERN ZONES MAY HAVE THE
BEST CHANCE FOR PRECIP. WITH THIS IN MIND...KEPT THE CHANCE POPS
FOCUSED IN THIS AREA AND CONTINUED A SLIGHT CHANCE EVERYWHERE
ELSE. OF COURSE...THIS DOES NOT COMPLETELY RULE OUT THE CHANCE FOR
THUNDERSTORMS FARTHER SOUTH...SINCE THOSE COUNTIES ARE EXPERIENCING
MORE-RAPID SURFACE HEATING DUE TO LESS CLOUD COVER.
HIGH PRESSURE WILL BUILD EASTWARD TONIGHT...AND WITH IT WILL RETURN
VERY WARM AND MUGGY WEATHER. HIGHS ARE FORECAST TO BE WELL ABOVE
SEASONAL AVERAGES TOMORROW...WITH MOST PLACES SEEING MID 80S TO
EVEN 90. WHILE THIS COULD LEAD TO PLENTY OF SURFACE
INSTABILITY...THERE DOES NOT SEEM TO BE ANY FOCUS FOR CONVECTION.
THE ONLY CONSIDERATION IS THE HIGHER ELEVATIONS...WHERE A FEW
THUNDERSTORMS COULD DEVELOP WITH THE HELP OF OROGRAPHIC LIFT. AT
THIS TIME THOUGH...MAINTAINED A DRY FORECAST FOR ALL OF TUESDAY.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
A VERY MOIST AND UNSTABLE AMS WILL RMN IN PLACE THRU THU OWING TO
PERSISTENT SWLY LOW-LVL FLOW. TUE NGT AND WED NGT WILL BOTH SEE
MINIMA IN THE 60S...WITH MINIMA APRCHG 70 TUE NGT.
SHWRS AND TSTMS WILL INCR IN CVRG ON WED AS A LOW-AMPLITUDE SHRTWV
TROF APRCHS AND UPR RDG FLATTENS. CLD CVR XPCD TO BE SUBSTANTIAL
OWING TO UNSTABLE AMS...WHICH MAY LMT MAXIMA SLGTLY COMPARED TO
TUE. HOWEVER...MAXIMA STILL XPCD TO REACH MID-UPR 80S.
LACK OF STRONG MID-LVL FLOW ON WED WILL YIELD RATHER ANEMIC SHEAR
DESPITE MDT INSTBY. WITH PWATS FCSTD IN EXCESS OF 1.8 IN...MAIN
CONCERN WILL BE FOR FLOODING FROM SLOW-MOVG TSTMS PRODUCING VERY
HVY RAIN.
BECAUSE THE FLY ALWAYS FINDS ITS OINTMENT...THE 12Z/09 NAM12 HAS
OFFERED A MUCH SLOWER ARRRIVAL OF THE CDFNT THAT WAS XPCD TO
ARRIVE ON THU. GFS/ECMWF STILL AGREE ON A MID-LATE DAY FROPA WHILE
NAM SUGGESTS AN ARRIVAL OVNGT THU NGT.
GIVEN CONSISTENCY OF GFS ENSEMBLE WITH GFS/ECMWF SOLUTIONS...THE
NAM12 SOLUTION WILL BE DEEMED AN OUTLIER...AND FCST TIMING WILL BE
MAINTAINED WITH FROPA DURG THU. WITH FAVORABLE TIMING OF FROPA AND
MINIMAL OVNGT CNVCTN XPCD...THU APPEARS QUITE FAVORABLE FOR WDSPRD
TSTMS ALONG THE ADVCG BNDRY. THUS...POPS WERE INCRD TO LKLY AS THE
BNDRY CROSSES AND MAXIMA WERE INCRD SLGTLY FOLLOWING THE TREND OF
LATEST GUIDANCE.
GUIDANCE ALSO SUGGESTS POST-FRONTAL CLDS WILL INVADE THU NGT AHD
OF SECONDARY PRES SURGE. CLD CVR WAS INCRD SGFNTLY LATE THU NGT...
WHICH WILL SLOW THE XPCD COOLING. THUS...THU NGT MINIMA WERE INCRD
A FEW DEG F.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A STG CDFNT WL CROSS THE RGN THU CONTG THE SHWR/TSTM CHCS. HIGH
PRES IS THEN EXPD TO BLD IN THRU THE WKEND. AFT FROPA...850MB
TEMPS DROP INTO THE SINGLE DIGITS...BOTTOMING OUT ARND 2 DEG C FRI
NGT. THIS WL BRING WELL BLO AVG TEMP FRI THRU SUN...ALTHOUGH SOME
MODERATION CAN BE EXPD SUN AS THE FLOW TURNS SRLY AND THE HIGH
SHIFTS EWD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
GENERAL VFR IS EXPECTED TO CONTINUE THROUGH MUCH OF THE PERIOD. A
LIFTING WARM FRONT WILL STILL PROVIDE THE CHANCE FOR SHOWERS AND
THUNDERSTORMS THIS AFTERNOON BUT AT THIS POINT COVERAGE IS
EXPECTED TO REMAIN SMALL. WILL MENTION VCTS IN THE SITES NORTH OF
PIT WHERE THE MODEL GUIDANCE CONTINUES TO SUGGEST THE GREATEST
PROBABILITY AND WILL MAINTAIN SCATTERED/BROKEN MID DECK EVERYWHERE
ELSE. ONE THING TO NOTE IS ANY TAF SITE THAT DOES EXPERIENCE A
SHOWER OR STORM WILL LIKELY EXPERIENCE IFR VISIBILITIES WITH
INCREASING LOW LEVEL MOISTURE.
WIND WILL GRADUALLY SHIFT TO SOUTHWESTERLY THROUGH THE AFTERNOON.
HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT...ENDING THE THREAT FOR
PRECIPITATION. WITH THE LOW LEVELS REMAINING MOIST...DO ANTICIPATE
SOME FOG IN SPOTS BUT LINGERING CLOUDS AND ELEVATED WIND MAY KEEP
IT MINIMAL.
.OUTLOOK.../MONDAY NIGHT THROUGH SATURDAY/...
GENERAL VFR IS EXPECTED UNTIL A COLD FRONT APPROACHES FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
34/KRAMAR
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1219 PM EDT MON SEP 9 2013
.SYNOPSIS...
HEAT AND HUMIDITY WILL BUILD THIS WEEK BEFORE THE PASSAGE OF A
STRONG COLD FRONT THURSDAY USHERS IN MUCH COOLER TEMPERATURES.
&&
.NEAR TERM /THROUGH TUESDAY/...
A WARM FRONT IS STILL PROGGED TO LIFT NORTH ACROSS THE REGION
LATER THIS AFTERNOON BUT QUESTION REMAINS ON HOW MUCH CONVECTION WE
WILL SEE WITH IT. DEWPOINTS HAVE ALREADY BEGUN TO REBOUND INTO THE
MID 60`S OVER EASTERN OHIO AND NORTHERN WEST VIRGINIA BUT
INSTABILITY REMAINS ELEVATED PER THE MOST RECENT MESOANALYSIS.
STILL THINK THAT WITH THE HELP OF A PASSING UPPER LEVEL
SHORTWAVE...THAT HAS SUPPORTED SOME SHOWERS AND STORMS OVER
MICHIGAN...THERE COULD BE AT LEAST SCATTERED SHOWERS AND STORMS
OVER OUR REGION TODAY. WHILE THERE ARE A FEW DIFFERENCES IN THE
DETERMINISTIC SOLUTIONS...THE RAP AND HRRR SEEM TO SUGGEST THAT
THE NORTHERN ZONES MAY HAVE THE BEST CHANCE FOR PRECIP. WITH THIS
IN MIND...KEPT THE CHANCE POPS FOCUSED IN THIS AREA AND CONTINUED
A SLIGHT CHANCE EVERYWHERE ELSE. OF COURSE...THIS DOES NOT
COMPLETELY RULE OUT THE CHANCE FOR THUNDERSTORMS FURTHER SOUTH
SINCE THOSE COUNTIES ARE EXPERIENCING MORE RAPID SURFACE HEATING
DUE TO LESS CLOUD COVER.
RIDGE OF HIGH PRESSURE WILL BUILD EASTWARD TONIGHT AND WITH IT
WILL RETURN VERY WARM AND MUGGY WEATHER. HIGHS ARE FORECAST TO BE
WELL ABOVE SEASONAL AVERAGES TOMORROW...WITH MOST PLACES SEEING
MID 80`S TO EVEN 90. WHILE THIS COULD LEAD TO PLENTY OF SURFACE
INSTABILITY...THERE DOESN`T SEEM TO BE ANY FOCUS FOR CONVECTION.
THE ONLY CONSIDERATION IS THE HIGHER ELEVATIONS WHERE A FEW
THUNDERSTORMS COULD DEVELOP WITH THE HELP OF OROGRAPHIC LIFT. AT THIS
TIME THOUGH...MAINTAINED A DRY FORECAST FOR ALL OF TUESDAY.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
RIDGE BREAKS DOWN WED...AS WEAK SHORTWAVE TROUGH SWINGS THROUGH.
THIS WILL PROVIDE A BETTER CHANCE FOR ACTIVITY WED AFTERNOON.
STILL TOUGH TO FIND A REAL STRONG TRIGGER...BUT THE ATMOSPHERE
REMAINS UNSTABLE AND THE UPPER LEVEL DISTURBANCE MAY BE ENOUGH TO
GET ACTIVITY GOING. SHEAR IS WEAK WED...SO NOT AS CONCERNED WITH
SEVERE POTENTIAL...HOWEVER WITH PWATS APPROACHING 1.8 INCHES AND
VERY LITTLE FLOW...THE POTENTIAL EXISTS FOR THE DEVELOPMENT OF
SLOW MOVING...HEAVY RAIN PRODUCING STORMS. CLOUD COVER WILL BE
CRUCIAL AS CONVECTIVE TEMPS ARE HIGH.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
A STG CDFNT WL CROSS THE RGN THU CONTG THE SHWR/TSTM CHCS. HIGH
PRES IS THEN EXPD TO BLD IN THRU THE WKEND. AFT FROPA...850MB
TEMPS DROP INTO THE SINGLE DIGITS...BOTTOMING OUT ARND 2 DEG C FRI
NGT. THIS WL BRING WELL BLO AVG TEMP FRI THRU SUN...ALTHOUGH SOME
MODERATION CAN BE EXPD SUN AS THE FLOW TURNS SRLY AND THE HIGH
SHIFTS EWD.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
GENERAL VFR IS EXPECTED TO CONTINUE THROUGH MUCH OF THE PERIOD. A
LIFTING WARM FRONT WILL STILL PROVIDE THE CHANCE FOR SHOWERS AND
THUNDERSTORMS THIS AFTERNOON BUT AT THIS POINT COVERAGE IS
EXPECTED TO REMAIN SMALL. WILL MENTION VCTS IN THE SITES NORTH OF
PIT WHERE THE MODEL GUIDANCE CONTINUES TO SUGGEST THE GREATEST
PROBABILITY AND WILL MAINTAIN SCATTERED/BROKEN MID DECK EVERYWHERE
ELSE. ONE THING TO NOTE IS ANY TAF SITE THAT DOES EXPERIENCE A
SHOWER OR STORM WILL LIKELY EXPERIENCE IFR VISIBILITIES WITH
INCREASING LOW LEVEL MOISTURE.
WIND WILL GRADUALLY SHIFT TO SOUTHWESTERLY THROUGH THE AFTERNOON.
HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT...ENDING THE THREAT FOR
PRECIPITATION. WITH THE LOW LEVELS REMAINING MOIST...DO ANTICIPATE
SOME FOG IN SPOTS BUT LINGERING CLOUDS AND ELEVATED WIND MAY KEEP
IT MINIMAL.
.OUTLOOK.../MONDAY NIGHT THROUGH SATURDAY/...
GENERAL VFR IS EXPECTED UNTIL A COLD FRONT APPROACHES FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
619 PM EDT MON SEP 9 2013
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 334 PM EDT MON SEP 9 2013
A WARM FRONT MOVED THROUGH WITH SOME HEAVY RAIN MONDAY MORNING.
THE RAIN IS GONE AND WARM AND HUMID WEATHER WILL BE AROUND UNTIL
TUESDAY NIGHT AND WEDNESDAY BEFORE A COLD FRONT USHERS IN SOME
VERY COOL TEMPERATURES FOR THE END OF THE WEEK.
&&
.UPDATE...
ISSUED AT 619 PM EDT MON SEP 9 2013
WE HAVE ISSUED AN UPDATE TO ADD IN A FEW SHOWERS/ISOLATED STORMS
FOR THE NEXT COUPLE OF HOURS UP NORTH FOR OSCEOLA AND CLARE
COUNTIES. A FEW SHOWERS WERE OCCURRING NORTH OF THE CWFA NORTH OF
THE WARM FRONT AND INTERACTING WITH AN OLD REMNANT MCV COMING IN
FROM THE W/NW. IT APPEARS THESE SHOULD MOVE OUT IN THE NEXT COUPLE
OF HOURS...AND ALLOW FOR THE EXPECTED DRY NIGHT OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 334 PM EDT MON SEP 9 2013
FORECAST ISSUES IN THE NEAR TERM ARE POTENTIAL FOR SOME SHOWERS
THIS EVENING...MAX TEMPS ON TUESDAY AND TIMING PRECIP ALONG THE
FRONT TUESDAY NIGHT THROUGH WEDNESDAY.
AS FOR WHAT HAPPENED LAST NIGHT...THE STORMS CERTAINLY
OUTPERFORMED THE FORECAST QPF AS MID LEVEL INSTABILITY COMBINED
WITH STRONG MOISTURE ADVECTION AND ISENTROPIC LIFT NORTH OF THE
SFC WARM FRONT. IT APPEARS THE REMNANTS OF AN MCS HELPED FOCUS THE
CONVECTION AS WELL...WITH RADAR LOOPS SHOWING AN MCV CIRCULATION
MOVING SOUTHEAST ACROSS THE FORECAST AREA CONCURRENT WITH THE DEEP
CONVECTION.
AS FOR LATE THIS AFTERNOON AND EVENING...THE SFC WARM FRONT
WILL BE LIFTING NORTH ACROSS LOWER MICHIGAN AND THE HRRR IS SHOWING
SHOWERS BRUSHING THE NORTHERN FORECAST AREA AS AN MCS MOVES EAST
ACROSS THE UPPER PENINSULA. WILL HAVE TO WATCH THIS. WENT WITH A
DRY FORECAST TONIGHT AS MODEL SOUNDINGS SHOW CAPPING INVERSION AS
WARM AIR CONTINUES TO ADVECT IN AT MID LEVELS.
EXPECT THE CAPPING TO CONTINUE TUESDAY EVEN AS SFC LOW MOVES
ACROSS NORTHERN LOWER MICHIGAN. WENT WITH A DRY FORECAST UP NORTH
WITH THE EXPECTATION THAT RAINS WILL HOLD OFF UNTIL FRONT BEGINS
TO SAG SOUTH TUESDAY NIGHT. SHOWERS AND STORMS CONTINUE TO SPREAD
SLOWLY SOUTH THROUGH WEDNESDAY. THE FRONT SHOULD CLEAR SOUTHERN
ZONES WEDNESDAY EVENING WITH SHOWERS ENDING FROM NORTH TO SOUTH.
.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 334 PM EDT MON SEP 9 2013
MAIN ITEMS TO FOCUS ON IN THE LONG TERM ARE THE COOL AIR MASS THAT
WILL SETTLE IN ACROSS THE AREA AND THEN THE PCPN CHCS OVER THE
WEEKEND WITH THE NEXT SYSTEM EXPECTED TO MOVE IN ACROSS THE AREA. NO
REAL CHANGES WERE MADE TO THE FCST AS THE LATEST DATA CONTINUES TO
SUPPORT THE GOING FCST.
THE FCST LOOKS LIKE IT SHOULD REMAIN DRY FROM THE THU THROUGH SAT
TIME FRAME. THE MAIN FRONT MOVING THROUGH WED SHOULD BE WELL SOUTH
OF THE AREA BY THU MORNING. IT APPEARS WE WILL SEE A SECONDARY FRONT
MOVING THROUGH ON THU. MOISTURE IS QUITE LIMITED ON THU SO WE DO
NOT EXPECT PCPN WITH THE SECONDARY FRONT.
THE HEART OF THE COLD AIR ALOFT WILL MOVE IN BY FRI MORNING. H850
TEMPS ARE EXPECTED TO BOTTOM OUT AROUND 0 TO 2C. THIS HAS THE
POTENTIAL TO PRODUCE LAKE EFFECT...HOWEVER THE MEAN LOW LEVEL FLOW
WILL BE NNE. THIS SHOULD KEEP LAKE EFFECT WEST AND WELL EAST OF THE
CWFA FROM LAKES MICHIGAN AND HURON RESPECTIVELY. SOME FROST WILL BE
POSSIBLE UP NORTH IN THE NORMALLY COLDER LOCATIONS. TEMPS WILL THEN
MODERATE A BIT FOR SAT AS SHORT WAVE RIDGING ALOFT MOVES IN AND AS
RETURN FLOW BEGINS TO SET UP IN THE LOWER LEVELS.
THE NEXT CHANCE OF RAIN WILL COME IN LATE SAT NIGHT AND DURING THE
DAY ON SUN. A STRONG RIDGE WILL BUILD ACROSS THE ROCKIES BY SUN.
THIS WILL HELP TO DIG A FAIRLY GOOD SHORT WAVE SE INTO THE AREA. NOT
A LOT OF INSTABILITY SHOWN BY THE MODELS FOR STORMS. THERE IS JUST
ENOUGH COMBINED WITH A WELL DEFINED SHORT WAVE TO JUSTIFY THE
MENTION FOR NOW. THIS SHOULD CLEAR OUT BY MON...PROVIDING ANOTHER
COOL DOWN FOR THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 140 PM EDT MON SEP 9 2013
WE EXPECT VFR CONDITIONS TO RULE FOR THE NEXT 24 HOURS AND LIKELY
BEYOND. MAIN ISSUE WILL BE SOME STRONGER WIND EXPECTED TO DEVELOP.
CONVECTION FROM THIS MORNING HAS WEAKENED CONSIDERABLY AND MOVED
WELL EAST OF THE AREA. SKIES ARE CLEARING OUT NICELY AS WE GET
INTO THE MUCH WARMER AIR. SKIES SHOULD REMAIN MAINLY CLEAR THROUGH
TONIGHT AND MOST OF TUE. A DECENT BREEZE EXPECTED TO INCREASE
TONIGHT SHOULD KEEP FOG POTENTIAL LIMITED EVEN WITH THE RECENT RAINFALL.
AS FAR AS THE WINDS ARE CONCERNED...THEY ARE EXPECTED TO INCREASE
THIS EVENING ACROSS THE TERMINALS. WE EXPECT A STEADY 10-12 KNOT
BREEZE EVERYWHERE OVERNIGHT WITH SOME GUSTS POSSIBLE AT KMKG NEAR
THE LAKESHORE. STRONGER WINDS AT AROUND 2K FT AGL WILL PRODUCE
SOME LOW LEVEL WIND SHEAR MAINLY DUE TO SPEED WITH 35-40 KNOTS OUT
OF THE SW. WE FEEL THERE IS NOT ENOUGH OF A DIFFERENCE TO INSERT
IT IN THE FCST...BUT IT WILL BE THERE. SOME WIND GUSTS TO 20 KNOTS
OR SO WILL BE LIKELY ON TUE AS DIURNAL MIXING TAKES PLACE.
&&
.MARINE...
ISSUED AT 334 PM EDT MON SEP 9 2013
WINDS AND WAVES ARE COMING UP AND SCA CONDITIONS EXPECTED TO
PERSIST INTO TUESDAY AFTERNOON.
&&
.HYDROLOGY...
ISSUED AT 334 PM EDT MON SEP 9 2013
HEAVY RAIN POTENTIAL IS LOW UNTIL TUESDAY NIGHT WEDNESDAY WHEN A
COLD FRONT MOVES THROUGH.
&&
.CLIMATE...
ISSUED AT 334 PM EDT MON SEP 9 2013
MAX TEMPS ON TUESDAY COULD CHALLENGE RECORDS AT THE THREE PRIMARY
CLIMATE SITES...ESPECIALLY MUSKEGON WHERE THE RECORD IS ONLY 88.
RECORD AT GRAND RAPIDS IS 94 AND LANSING 93.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH TUESDAY AFTERNOON FOR MIZ037-043-
050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 4 PM EDT TUESDAY FOR LMZ844>849.
&&
$$
UPDATE...NJJ
SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...OSTUNO
CLIMATE...OSTUNO
MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
421 PM EDT MON SEP 9 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 419 PM EDT MON SEP 9 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MID LEVEL LOW OVER NE
MT. LOW IS WEAKENING/OPENING UP ON WATER VAPOR LOOP/ANALYSIS AND IS
FCST TO MOVE E THROUGH THE NRN PLAINS STATES TONIGHT. ASSOC SFC LOW
NOW OVER SW MN IS IN TURN FCST TO LIFT NE ACROSS THE FCST AREA
TONIGHT WITH APPROACH OF NRN PLAINS SHORTWAVE. STRONG WAA/ISENTROPIC
LIFT AHEAD OF FRONTAL BOUNDARY AS IT LIFTS FM SRN WI TOWARD SCNTRL
UPR MI THIS EVENING WILL PROVIDE FOCUS FOR ANOTHER ROUND OF
CONVECTION TONIGHT WITH THE POTENTIAL FOR STRONG TO POSSIBLY SVR
STORMS.
TONIGHT...BIGGEST THING GOING AGAINST SVR WX TONIGHT WILL BE LACK OF
SFC-BASED INSTABILITY FM TODAY DUE TO THICK CLOUDS PERSISTING OVER
THE AREA FM EARLIER MCS OVER THE NRN PLAINS. EVEN SO...COMBINATION
OF STRENGTHING LOW-LVL JET...INCREASING WAA/ISENTROPIC LIFT AND
ADVANCE OF WARM FRONTAL BOUNDARY TOWARD SCNTRL FCST AREA WILL ALLOW
FOR INCREASING ELEVATED INSTABILITY (NAM AND RUC SHOW ELEVATED CAPES
IN EXCESS OF 2000 J/KG THIS EVENING) AND DEEP LAYER SHEAR TO 45-50
KT WHICH COULD BRING POTENTIAL FOR STRONG TO POSSIBLY SVR
STORMS...WITH THE BEST THREAT FOR SVR OVER SCNTRL MI AND SE UPR MI
IN CLOSER PROXIMITY TO ADVANCING WARM FRONT. GIVEN LACK OF SFC-BASED
INSTABILITY...THERE MAY BE MORE OF A THREAT OF ELEVATED STORMS WITH
LARGE HAIL PERHAPS BEING THE BIGGER THREAT FOR OUR AREA. WILL
CONTINUE TO MENTION STRONG TO SEVERE STORMS IN THE HWO WITH THE BEST
THREAT OF HEAVY RAINFALL ACROSS NRN UPR MI AND THE KEWEENAW
PENINSULA. MODEL QPF STILL SUGGESTS THE KEWEENAW PENINSULA AND ERN
UPR MI WILL HAVE BEST CHC FOR HEAVY RAINFALL TONIGHT. LOOK FOR A
GENERAL DIMINISHING TREND IN CONVECTION OVERNIGHT (AFT 06Z) AS
LOW-LVL JET VEERS FM SW TO A MORE WRLY DIRECTION.
DENSE FOG HAS BEEN OBSERVED OVER THE KEWEENAW PENINSULA AND LAKE
SUPERIOR THIS AFTERNOON AND WOULD EXPECT FOG TO CONTINUE INTO THIS
EVENING WITH SHRA MOVING OVER THE AREA AND ONSHORE E-SE FLOW
PERSISTING. EXPECT PATCHY FOG TO MOVE ONSHORE TO NRN ZONES LATE
TONIGHT AS WIND SHIFTS N-NW BEHIND SFC TROUGH.
TUESDAY...THERE COULD BE SOME LINGERING UPSLOPE DZ IN THE MORNING
OVER NRN ZONES AS LOW-LVLS REMAIN MOIST. SOME ISOLD SHRA ARE ALSO
POSSIBLE MAINLY OVER SCNTRL AND ERN SECTIONS OF THE CWA UNTIL
LINGERING SFC BOUNDARY SAGS SE OF THE AREA LATE IN THE DAY.
PERSISTENT CLOUDS OVER THE AREA WILL RESULT IN HIGH TEMPS RANGING
FROM THE 60S NEAR LAKE SUPERIOR IN ONSHORE FLOW TO THE MID 70S
SCNTRL AND EAST ALONG FRONTAL BOUNDARY.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 419 PM EDT MON SEP 9 2013
A WEAK HIGH PRESSURE RIDGE WILL SLIDE OVER THE AREA ON TUESDAY
NIGHT BEHIND THE EXITING LOW PRESSURE SYSTEM. WITH THE AREA STILL
UNDER THE RIGHT REAR OF THE UPPER JET...A WEAK SHORTWAVE MOVING
THROUGH...AND SOME LINGERING MOISTURE...OPTED TO LINGER A FEW
ISOLATED SHOWERS NEAR LAKE MICHIGAN FOR THE FIRST PART OF THE
EVENING.
ATTENTION THEN TURNS TO THE SHORTWAVE THAT IS CURRENTLY IN THE
WESTERN PART OF THE NORTHWEST TERRITORIES. THIS SHORTWAVE WILL DIVE
SOUTHEAST TO LAKE WINNIPEG BY 12Z WEDNESDAY AND THEN THROUGH THE
UPPER GREAT LAKES WEDNESDAY NIGHT AND CONTINUE TO INFLUENCE THE
WEATHER INTO THURSDAY. A LOW PRESSURE SYSTEM ASSOCIATED WITH THIS
SHORTWAVE WILL TRACK ACROSS NORTHERN ONTARIO AND SWEEP THE MAIN COLD
FRONT ACROSS THE CWA LATE WEDNESDAY MORNING AND INTO THE AFTERNOON.
A WEAK TROUGH WILL TRY TO SLIDE ACROSS THE AREA LATE TUESDAY
NIGHT...WHICH COULD PRODUCE A FEW SHOWERS. BUT THE BEST CHANCE WILL
BE IN THE AFTERNOON WITH THE MAIN FRONT AND ASSISTANCE FROM DIURNAL
HEATING. THE MAIN INHIBITING FACTOR FOR MORE WIDESPREAD SHOWERS IS
THE SPLOTCHY NATURE OF THE DEEPER MOISTURE IN THE MODELS.
THUS...WILL GO FOR MORE LOW END CHANCES...WITH THE HIGHEST OVER THE
EAST BASED OFF THE TIMING OF THE FRONT WITH PEAK HEATING. DID CAP
THUNDER MENTION AT SLIGHT CHANCES...DUE TO THE WIDE VARIETY OF
MLCAPE VALUES IN THE MODELS (RANGING FROM 200-700 J/KG).
THURSDAY WILL BE COOL AND BREEZY ACROSS THE AREA WITH THE TIGHT
PRESSURE GRADIENT AS HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS.
850MB TEMPS WILL FALL FROM AROUND 11C ON WEDNESDAY TO 0-2C BY 00Z
THURSDAY. THE COOL TEMPERATURES OVER THE WARM LAKE WATERS WILL
COMBINE WITH THE LOW LEVEL MOISTURE SHOWN ON BOTH ECMWF/GFS FOR
LAKE INDUCED CLOUDS AND PROBABLY A FEW SHOWERS OVER THE LOCATIONS
FAVORED BY NORTH-NORTHWEST WINDS. EXPECT THE STRONGEST WIND GUSTS
TO BE OVER THE EASTERN CWA...WHERE WINDS WILL BE GUSTING TO
30MPH. WITH TEMPERATURES IN THE UPPER 50S AND LOWER 60S...THE
CLOUDS/WINDS/SHOWERS WILL LEAD TO A VERY OCTOBER LIKE DAY FOR MID
SEPTEMBER.
THE HIGH WILL BUILD SOUTHEAST ON THURSDAY NIGHT AND BE CENTERED
OVER THE AREA FOR FRIDAY AFTERNOON AND EVENING. THE DRY AIR
ASSOCIATED WITH THE HIGH WILL DIMINISH THE CLOUDS...BUT ALSO BRING
THE POTENTIAL FOR FROST OVER THE INTERIOR LOCATIONS THURSDAY NIGHT
AND FRIDAY NIGHT. CONFIDENCE IS FAIRLY LOW FOR THURSDAY NIGHT...AS
IT WILL DEPEND ON THE TIMING OF THE EXITING CLOUDS AND ALSO THE
WINDS WEAKENING UP FOR DECENT RADIATIONAL COOLING. THINK THE WESTERN
CWA WILL HAVE THE BEST CHANCE ON THURSDAY NIGHT AND WILL CONTINUE
THE COOLEST TEMPS THERE. THE CENTRAL AND EAST WILL HAVE THE BEST
SHOT FOR FROST ON FRIDAY NIGHT...SINCE THEY WILL BE THE CLOSEST TO
THE HIGH CENTER WITH THE LIGHTER WINDS. OVER THE FAR
WEST...SOUTHERLY RETURN FLOW ON THE BACK SIDE OF THE HIGH ON
FRIDAY NIGHT PRODUCES A LITTLE MORE UNCERTAINTY ON HOW COLD THE
TEMPS WILL GET BEFORE WINDS BEGIN TO PICK UP.
UPPER RIDGE WILL MOVE INTO THE AREA FOR SATURDAY AND BRING
TEMPERATURES BACK UP TOWARDS THE MID-UPPER 60S. THE NEXT SYSTEM
LOOKS TO AFFECT THE AREA ON SATURDAY NIGHT INTO SUNDAY. THIS
SHORTWAVE AND SURFACE LOW LOOK TO TAKE A SIMILAR TRACK TO THE ONE
THIS WEDNESDAY...ALTHOUGH THERE APPEARS TO BE A BETTER OPPORTUNITY
FOR RETURN FLOW TO PROVIDE MORE MOISTURE FOR SHOWERS AS THE FRONT
MOVES THROUGH. INSTABILITY AND MID-LEVEL LAPSE RATES ARE VERY
WEAK...SO HAVE LEFT THE MENTION OF THUNDER OUT OF THE FORECAST.
ONCE AGAIN...HIGH PRESSURE AND COOLER 850MB TEMPS WILL MOVE IN FOR
SUNDAY AFTERNOON INTO MONDAY...BRINGING ANOTHER BELOW NORMAL
TEMPERATURE DAY FOR MONDAY. GFS/ECMWF DO DIFFER ON THE AMOUNT OF
LOW LEVEL MOISTURE PRESENT FOR SUNDAY NIGHT INTO MONDAY...BUT WITH
THE COLD TEMPERATURES ALOFT IT SHOULDN/T TAKE MUCH TO KICK OF LAKE
CLOUDS OR EVEN SOME SHOWERS (AT LEAST FOR SUNDAY NIGHT).
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 140 PM EDT MON SEP 9 2013
WARM/MOIST AIR SURGING INTO THE UPPER GREAT LAKES IN A SE FLOW WILL
RESULT IN GENERALLY IFR TO OCCASIONAL LIFR CIGS AND OCCASIONAL SHRA THRU
THE DAY AT KIWD/KCMX/KSAW. POTENTIAL FOR ADDITIONAL CONVECTION WILL
RETURN THIS EVENING. CONDITIONS AT ALL TERMINALS SHOULD FALL TO IFR
OR LOWER TONIGHT...ESPECIALLY AS WINDS BECOME UPSLOPE AT EACH
TERMINAL.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 419 PM EDT MON SEP 9 2013
LOW PRESSURE OVER NORTHEAST SD WILL LIFT INTO CENTRAL AND ERN UPR MI
TONIGHT AND THEN INTO FAR SE ONTARIO ON TUESDAY. NE WINDS FUNNELING
DOWN THE WRN PORTION OF LAKE SUPERIOR COULD GUST OVER 20 KT THIS
EVENING ON THE BACKSIDE OF THE LOW. A BRIEF RIDGE WILL MOVE OVER
LAKE SUPERIOR TUESDAY AFTERNOON THROUGH TUESDAY NIGHT...OUT AHEAD OF
A WEAK TROUGH EXTENDING FROM NORTHERN ONTARIO DURING THE DAY
WEDNESDAY. LARGE HIGH PRESSURE OVER SOUTH CENTRAL CANADA WEDNESDAY
NIGHT WILL SLOWLY SINK ACROSS GREAT LAKES...WHERE IT WILL REMAIN
FROM THURSDAY NIGHT THROUGH FRIDAY NIGHT. NW WINDS WILL LIKELY GUST
20-30KTS LATE WEDNESDAY NIGHT THROUGH LATE THURSDAY NIGHT AS HIGH
PRESSURE SINKS IN FROM THE NNW. OTHERWISE WITH HIGH PRESSURE
OVERHEAD...LIGHT WINDS LESS THAN 20KTS ARE EXPECTED BY FRIDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
335 PM EDT MON SEP 9 2013
LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/CLIMATE/MARINE
.SYNOPSIS...
ISSUED AT 334 PM EDT MON SEP 9 2013
A WARM FRONT MOVED THROUGH WITH SOME HEAVY RAIN MONDAY MORNING.
THE RAIN IS GONE AND WARM AND HUMID WEATHER WILL BE AROUND UNTIL
TUESDAY NIGHT AND WEDNESDAY BEFORE A COLD FRONT USHERS IN SOME
VERY COOL TEMPERATURES FOR THE END OF THE WEEK.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 334 PM EDT MON SEP 9 2013
FORECAST ISSUES IN THE NEAR TERM ARE POTENTIAL FOR SOME SHOWERS
THIS EVENING...MAX TEMPS ON TUESDAY AND TIMING PRECIP ALONG THE
FRONT TUESDAY NIGHT THROUGH WEDNESDAY.
AS FOR WHAT HAPPENED LAST NIGHT...THE STORMS CERTAINLY
OUTPERFORMED THE FORECAST QPF AS MID LEVEL INSTABILITY COMBINED
WITH STRONG MOISTURE ADVECTION AND ISENTROPIC LIFT NORTH OF THE
SFC WARM FRONT. IT APPEARS THE REMNANTS OF AN MCS HELPED FOCUS THE
CONVECTION AS WELL...WITH RADAR LOOPS SHOWING AN MCV CIRCULATION
MOVING SOUTHEAST ACROSS THE FORECAST AREA CONCURRENT WITH THE DEEP
CONVECTION.
AS FOR LATE THIS AFTERNOON AND EVENING...THE SFC WARM FRONT
WILL BE LIFTING NORTH ACROSS LOWER MICHIGAN AND THE HRRR IS SHOWING
SHOWERS BRUSHING THE NORTHERN FORECAST AREA AS AN MCS MOVES EAST
ACROSS THE UPPER PENINSULA. WILL HAVE TO WATCH THIS. WENT WITH A
DRY FORECAST TONIGHT AS MODEL SOUNDINGS SHOW CAPPING INVERSION AS
WARM AIR CONTINUES TO ADVECT IN AT MID LEVELS.
EXPECT THE CAPPING TO CONTINUE TUESDAY EVEN AS SFC LOW MOVES
ACROSS NORTHERN LOWER MICHIGAN. WENT WITH A DRY FORECAST UP NORTH
WITH THE EXPECTATION THAT RAINS WILL HOLD OFF UNTIL FRONT BEGINS
TO SAG SOUTH TUESDAY NIGHT. SHOWERS AND STORMS CONTINUE TO SPREAD
SLOWLY SOUTH THROUGH WEDNESDAY. THE FRONT SHOULD CLEAR SOUTHERN
ZONES WEDNESDAY EVENING WITH SHOWERS ENDING FROM NORTH TO SOUTH.
.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 334 PM EDT MON SEP 9 2013
MAIN ITEMS TO FOCUS ON IN THE LONG TERM ARE THE COOL AIR MASS THAT
WILL SETTLE IN ACROSS THE AREA AND THEN THE PCPN CHCS OVER THE
WEEKEND WITH THE NEXT SYSTEM EXPECTED TO MOVE IN ACROSS THE AREA. NO
REAL CHANGES WERE MADE TO THE FCST AS THE LATEST DATA CONTINUES TO
SUPPORT THE GOING FCST.
THE FCST LOOKS LIKE IT SHOULD REMAIN DRY FROM THE THU THROUGH SAT
TIME FRAME. THE MAIN FRONT MOVING THROUGH WED SHOULD BE WELL SOUTH
OF THE AREA BY THU MORNING. IT APPEARS WE WILL SEE A SECONDARY FRONT
MOVING THROUGH ON THU. MOISTURE IS QUITE LIMITED ON THU SO WE DO
NOT EXPECT PCPN WITH THE SECONDARY FRONT.
THE HEART OF THE COLD AIR ALOFT WILL MOVE IN BY FRI MORNING. H850
TEMPS ARE EXPECTED TO BOTTOM OUT AROUND 0 TO 2C. THIS HAS THE
POTENTIAL TO PRODUCE LAKE EFFECT...HOWEVER THE MEAN LOW LEVEL FLOW
WILL BE NNE. THIS SHOULD KEEP LAKE EFFECT WEST AND WELL EAST OF THE
CWFA FROM LAKES MICHIGAN AND HURON RESPECTIVELY. SOME FROST WILL BE
POSSIBLE UP NORTH IN THE NORMALLY COLDER LOCATIONS. TEMPS WILL THEN
MODERATE A BIT FOR SAT AS SHORT WAVE RIDGING ALOFT MOVES IN AND AS
RETURN FLOW BEGINS TO SET UP IN THE LOWER LEVELS.
THE NEXT CHANCE OF RAIN WILL COME IN LATE SAT NIGHT AND DURING THE
DAY ON SUN. A STRONG RIDGE WILL BUILD ACROSS THE ROCKIES BY SUN.
THIS WILL HELP TO DIG A FAIRLY GOOD SHORT WAVE SE INTO THE AREA. NOT
A LOT OF INSTABILITY SHOWN BY THE MODELS FOR STORMS. THERE IS JUST
ENOUGH COMBINED WITH A WELL DEFINED SHORT WAVE TO JUSTIFY THE
MENTION FOR NOW. THIS SHOULD CLEAR OUT BY MON...PROVIDING ANOTHER
COOL DOWN FOR THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 140 PM EDT MON SEP 9 2013
WE EXPECT VFR CONDITIONS TO RULE FOR THE NEXT 24 HOURS AND LIKELY
BEYOND. MAIN ISSUE WILL BE SOME STRONGER WIND EXPECTED TO DEVELOP.
CONVECTION FROM THIS MORNING HAS WEAKENED CONSIDERABLY AND MOVED
WELL EAST OF THE AREA. SKIES ARE CLEARING OUT NICELY AS WE GET
INTO THE MUCH WARMER AIR. SKIES SHOULD REMAIN MAINLY CLEAR THROUGH
TONIGHT AND MOST OF TUE. A DECENT BREEZE EXPECTED TO INCREASE
TONIGHT SHOULD KEEP FOG POTENTIAL LIMITED EVEN WITH THE RECENT RAINFALL.
AS FAR AS THE WINDS ARE CONCERNED...THEY ARE EXPECTED TO INCREASE
THIS EVENING ACROSS THE TERMINALS. WE EXPECT A STEADY 10-12 KNOT
BREEZE EVERYWHERE OVERNIGHT WITH SOME GUSTS POSSIBLE AT KMKG NEAR
THE LAKESHORE. STRONGER WINDS AT AROUND 2K FT AGL WILL PRODUCE
SOME LOW LEVEL WIND SHEAR MAINLY DUE TO SPEED WITH 35-40 KNOTS OUT
OF THE SW. WE FEEL THERE IS NOT ENOUGH OF A DIFFERENCE TO INSERT
IT IN THE FCST...BUT IT WILL BE THERE. SOME WIND GUSTS TO 20 KNOTS
OR SO WILL BE LIKELY ON TUE AS DIURNAL MIXING TAKES PLACE.
&&
.MARINE...
ISSUED AT 334 PM EDT MON SEP 9 2013
WINDS AND WAVES ARE COMING UP AND SCA CONDITIONS EXPECTED TO
PERSIST INTO TUESDAY AFTERNOON.
&&
.HYDROLOGY...
ISSUED AT 334 PM EDT MON SEP 9 2013
HEAVY RAIN POTENTIAL IS LOW UNTIL TUESDAY NIGHT WEDNESDAY WHEN A
COLD FRONT MOVES THROUGH.
&&
.CLIMATE...
ISSUED AT 334 PM EDT MON SEP 9 2013
MAX TEMPS ON TUESDAY COULD CHALLENGE RECORDS AT THE THREE PRIMARY
CLIMATE SITES...ESPECIALLY MUSKEGON WHERE THE RECORD IS ONLY 88.
RECORD AT GRAND RAPIDS IS 94 AND LANSING 93.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH TUESDAY AFTERNOON FOR MIZ037-043-
050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 4 PM EDT TUESDAY FOR LMZ844>849.
&&
$$
SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...OSTUNO
CLIMATE...OSTUNO
MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
159 PM EDT MON SEP 9 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 536 AM EDT MON SEP 9 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MID LEVEL LOW OVER MT.
LOW IS WEAKENING/OPENING UP AND FINALLY MOVING E AFTER BEING OVER
THE PACIFIC NW DURING THE LAST FEW DAYS. AHEAD OF THIS FEATURE...
SHRA/TSRA OVER THE WRN DAKOTAS LAST EVENING HAVE ORGANIZED INTO A
WELL DEVELOPED MCS WHICH IS NOW MOVING ACROSS THE ERN DAKOTAS. PER
LATEST RUC/SPC MESOANALYSIS...40-50KT LOW-LEVEL JET IS ADVECTING
MUCAPE OF 3000J/KG INTO THE COMPLEX...HELPING TO MAINTAIN IT. MCS IS
MOVING AROUND A WEAKENING RIDGE WHICH REMAINS OVER THE CNTRL CONUS.
CLOSER TO HOME...SOME -SHRA...MOSTLY JUST SPRINKLES...HAVE PUSHED
ACROSS THE WRN AND SRN FCST AREA OVERNIGHT IN A GENERALLY WEAK
ISENTROPIC ASCENT REGIME. OVER THE LAST COUPLE OF HRS...SOUTHERLY
FLOW UP LAKE MICHIGAN HAS INCREASED ENOUGH TO BEGIN PUSHING HIGHER
DWPT MARINE LAYER AIR INTO THE ERN FCST AREA. WITH TEMPS IN THE
INTERIOR IN THE 40S/LWR 50S...MAY SEE SOME FOG/STRATUS DEVELOP THERE
IN THE NEXT COUPLE OF HRS.
INITIALLY...WILL CARRY ISOLD/SCT SHRA ACROSS THE FCST AREA FOR THE
NEXT SEVERAL HRS IN ONGOING MODEST WAA/ISENTROPIC ASCENT. THEN...
SHORT TERM FCST WILL REVOLVE AROUND PROGRESS OF THE SYSTEM OVER MT
AND MORE IMPORTANTLY THE MCS OVER THE DAKOTAS. AS ALWAYS...PINNING
DOWN CONVECTION EVEN IN THE SHORT TERM IS A CHALLENGE. TODAYS FCST
IS ESPECIALLY CHALLENGING GIVEN THE WELL-DEVELOPED MCS NOW OVER THE
ERN DAKOTAS AS IT SEEMS QUITE LIKELY THAT AN MCV WILL SPIN UP AND
MAY BECOME THE MAIN FEATURE TO KEY ON FOR THE PCPN FCST HERE. TRIED
TO INCORPORATE THE IDEA OF THE MCS HOLDING TOGETHER TO SOME EXTENT.
AS IT LIFTS ENE...MAY SEE AN ARC OF SHRA/TSRA SWING ACROSS
ESPECIALLY NW UPPER MI LATER THIS MORNING IN ZONE OF ENHANCED
WAA/ISENTROPIC ASCENT. WHAT TRANSPIRES AFTERWARDS IS UNCERTAIN. IF
MCV TRACKS N OF THE AREA...THE MAIN CLUSTER OF SHRA/TSRA WILL PASS
MOSTLY N OF UPPER MI TODAY WITH TAIL OF WAVE POSSIBLY GENERATING A
BAND OF SVR STORMS LATE AFTN/EVENING AS MLCAPE UPWARDS OF 2000J/KG
BUILDS NE INTO UPPER MI IN THE PRESENCE OF 40-50KT DEEP LAYER SHEAR.
IF MCV PASSES ACROSS UPPER MI...THEN MOST AREAS WILL SEE A FEW HRS
OF SHRA/TSRA THIS AFTN...AND MAIN SVR THREAT COULD BE SHUNTED S FOR
THE LATE AFTN/EVENING. BASED ON RADAR TRENDS...IT APPEARS THE FORMER
IDEA MAY BE THE MORE LIKELY SCENARIO. DEPENDING ON HOW FAR N WARM
SECTOR CAPPED AIR MASS ADVECTS TODAY...SRN FCST AREA MAY SEE
LITTLE/NO CONVECTION AFTER INITIAL POSSIBLE SHRA/TSRA IN
AFORMENTIONED ZONE OF ENHANCED WAA/ISENTROPIC ASCENT PASSES LATER
THIS MORNING.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 412 AM EDT MON SEP 9 2013
TUESDAY MORNING WILL MARK THE BEGINNING OF A COOLER AND GENERALLY
DRIER TREND THAT WILL REMAIN THROUGH THE REST OF THE FCST PERIOD.
850MB TEMPS AT DAYBREAK TUESDAY SHOULD BE 14-19C...WHICH WILL NOT BE
SEEN AGAIN UNTIL NEXT TUESDAY AT THE EARLIEST.
THE SFC LOW WILL BE EXITING/SLOWLY SINKING TO OUR SE ON TUESDAY...AS
A RIDGE BRIEFLY SLIDES IN. WHILE THERE WILL BE A PERIOD OF DRY
WEATHER...IT WILL BE SHORT LIVED...AS A SERIES OF SHORTWAVES WILL
KEEP IMPACTING THE UPPER GREAT LAKES THROUGH THE DAY THURSDAY.
HIGH PRESSURE WILL BUILD IN AT THE SFC AND ALOFT THURSDAY NIGHT. THE
COLDEST AIR WILL LIKELY BE OVERHEAD THURSDAY NIGHT INTO FRIDAY
MORNING...WITH BOTH THE GFS AND ECMWF INDICATING 850MB TEMPS BETWEEN
0 AND -2C FROM 00Z-12Z FRIDAY ON NNW-NE WINDS OFF LAKE SUPERIOR.
WHILE THERE WILL BE SOME DRYING THURSDAY NIGHT WITH HIGH PRESSURE
ROLLING IN...DIMINISHING 15-20KTS WINDS OFF LAKE SUPERIOR WILL HELP
KEEP LOW LEVEL MOISTURE STUCK ACROSS N UPPER MI INTO FRIDAY MORNING
AS A STRENGTHENING INVERSION TAKES HOLD. FRIDAY MORNING TEMPERATURES
ARE TRICKY. THE 09/00Z RUN OF THE GFS WARMED 850MB TEMPS 2C ON
AVERAGE...WHICH IS APPROX 3-4C WARMER THAN THE 09/12Z ECMWF.
AS THE SFC HIGH EXITS FRIDAY AFTERNOON/EVENING...SLIGHTLY WARMER AIR
WILL BE ABLE TO SWING IN ON W-SW WINDS. THERE WILL STILL BE THE
POTENTIAL FOR PATCHY FROST...BUT MOST LIKELY OVER THE INLAND E
LOCATIONS THAT ARE STILL UNDER THE LINGER INFLUENCE OF THE EXITING
HIGH. WHILE 80 DEGREE TEMPS WILL NOT RETURN...50 DEGREE READING ON
FRIDAY WILL RISE INTO THE MID 60S FOR THE UPCOMING WEEKEND. THE
WARMER TEMPERATURES WILL BE ACCOMPANIED BY A CHANCE OF SHOWERS TO
WRAP UP THE WEEKEND. WILL KEEP THE MENTION OF TS OUT FOR SUNDAY...AS
THE BEST POTENTIAL SHOULD REMAIN WELL TO OUR SW...CLOSER TO THE SFC
LOW ACROSS THE CENTRAL PLAINS WHERE MUCH WARMER AIR WILL RESIDE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 140 PM EDT MON SEP 9 2013
WARM/MOIST AIR SURGING INTO THE UPPER GREAT LAKES IN A SE FLOW WILL
RESULT IN GENERALLY IFR TO OCCASIONAL LIFR CIGS AND OCCASIONAL SHRA THRU
THE DAY AT KIWD/KCMX/KSAW. POTENTIAL FOR ADDITIONAL CONVECTION WILL
RETURN THIS EVENING. CONDITIONS AT ALL TERMINALS SHOULD FALL TO IFR
OR LOWER TONIGHT...ESPECIALLY AS WINDS BECOME UPSLOPE AT EACH
TERMINAL. &&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 AM EDT MON SEP 9 2013
LOW PRESSURE OVER SD WILL PUSH THE EXITING RIDGE ACROSS LAKE
SUPERIOR EASTWARD TODAY. FUNNELING NE WINDS WILL GUST TO 20-25KTS
OVER FAR W LAKE SUPERIOR THIS AFTERNOON AND EVENING. EXPECT THE LOW
TO CROSS S LAKE SUPERIOR OVERNIGHT...AND PUSH INTO FAR SE ONTARIO ON
TUESDAY. A BRIEF RIDGE WILL MOVE OVER LAKE SUPERIOR TUESDAY
AFTERNOON THROUGH TUESDAY NIGHT...OUT AHEAD OF A WEAK TROUGH
EXTENDING FROM NORTHERN ONTARIO DURING THE DAY WEDNESDAY. LARGE HIGH
PRESSURE OVER SOUTH CENTRAL CANADA WEDNESDAY NIGHT WILL SLOWLY SINK
ACROSS GREAT LAKES...WHERE IT WILL REMAIN FROM THURSDAY NIGHT
THROUGH FRIDAY NIGHT. NW WINDS WILL LIKELY GUST 20-30KTS LATE
WEDNESDAY NIGHT THROUGH LATE THURSDAY NIGHT AS HIGH PRESSURE SINKS
IN FROM THE NNW. OTHERWISE WITH HIGH PRESSURE OVERHEAD...LIGHT WINDS
LESS THAN 20KTS ARE EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...VOSS
MARINE...KF
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1209 PM CDT Mon Sep 9 2013
.UPDATE...
Issued at 603 AM CDT MON SEP 9 2013
As noted in the 352 am discussion below an accas field has quickly
formed over the eastern portion of the CWA with widely scattered
elevated convection now being detected by radar. Have updated the
zones/grids to reflect this. Activity is expected to be short-lived
and dissipate by late morning.
&&
.SHORT TERM...(Today through Tuesday)
Issued at 352 AM CDT MON SEP 9 2013
The unseasonably hot conditions will continue today with near record
heat in parts of northern and west central MO. While H8 and 925mb
temperatures are progged to be 1-2C lower than Sunday when triple
digit readings were reached in the KC Metro, mixing will be better
and deeper due to increasing southwest winds. The net effect will be
afternoon temperatures topping out in the middle to upper 90s. If
there is any silver lining to today`s heat it`s the expectation of
lower humidity levels due to this better mixing.
The large anticyclone aloft will be nearly overhead and with its hot
mid level temperatures will suppress most cloud clover let alone any
convective development. However, there is one caveat to this
scenario and it revolves around a weak surface trough extending from
near OMA southeast through central MO. Some of the very short range
models like the RAP and HRRR are hinting at some elevated convection
near this boundary +/- 2-3 hours centered around 12Z. While the
models have been overly generous with qpf the last couple days with
the boundaries that have migrated into the CWA the latest satellite
imagery shows patches of apparently mid clouds forming from far east
central KS to central MO. Will need to monitor radar/satellite for
any development as the current forecast is dry.
Tuesday: more of the same although temperatures look like they will
be a few degrees cooler as the pool of hot air shifts northward.
Nonetheless, temperatures will remain a good 10F above average.
Lacking any boundary and with nearly non-existent moisture under a
strong cap will go with zero PoPs.
Tuesday night: A cold front from southern NE through WI will sag
slowly southward and possibly reach far northwest MO by Wednesday
morning. Models are becoming more reluctant to generate qpf over the
CWA as any convection which forms during this period will likely be
post-frontal. Have confined PoPs to far northwest MO and left rest
of CWA dry.
.LONG TERM...(Wednesday through Sunday)
Issued at 352 AM CDT MON SEP 9 2013
A rather weak front is expected to sink into northern Missouri by
Wednesday morning, but with limited precipitation accompanying it.
A narrow corridor of low level moisture will stretch across southern
Nebraska eastward into central Illinois into Thursday. Depending on
cloud cover, temperatures may again climb into the lower or even
middle 90s Wednesday afternoon and while low, a few thunderstorms
may develop in the unstable airmass south of the boundary.
Slightly higher PoPs are focused Wednesday night into Thursday as
the low-level baroclinic zone shifts southward. However, the LLJ
will back through the night into NW Kansas and SW Nebraska likely
forcing higher precipitation chances well west of the local area.
A secondary cold front will sweep into the area Thursday night,
allowing cool and dry air to push southwest. Temperatures heading
into the weekend will find themselves near the seasonal normals in
the upper 70s to lower 80s. An upper low crossing the Rockies over
the weekend will allow winds to turn back southwesterly on Saturday,
before another front moves into the area Sunday/Monday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1206 PM CDT MON SEP 9 2013
VFR conditions will persist through the forecast period, with mainly
clear skies and southwest winds. Wind speeds will increase over the
next hour or so and remain sustained at around 15 kts this afternoon,
with occasional gusts over 20 kts. Speeds will decrease a bit this
evening, but should stay above 5 kts overnight.
&&
.FIRE WEATHER...
Issued at 352 AM CDT MON SEP 9 2013
There is an elevated fire danger threat this afternoon across
northern and west central MO as well as extreme east central KS. The
heat of the past several days has quickly dried out the native
grasses. This combined with drought conditions across the area plus
humidity levels between 25 and 30 percent and southwest winds gusting
to 20 to 25 mph will increase the risk of rapid fire growth which
could quickly burn out of control.
&&
.CLIMATE...
Issued at 352 AM CDT MON SEP 9 2013
Record or near record heat is expected Monday afternoon over parts of
northern and west central MO and extreme east central KS.
Sep 9 record high/year
St. Joseph 98/1955
Kansas City 99/1970
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
UPDATE...MJ
SHORT TERM...MJ
LONG TERM...Dux
AVIATION...Laflin
FIRE WEATHER...MJ
CLIMATE...MJ
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1131 AM CDT Mon Sep 9 2013
.UPDATE:
Issued at 552 AM CDT Mon Sep 9 2013
Did a quick update, a few isolated thunderstorms have developed
over Marion and Fayette counties in southern IL. Latest HRRR run
shows even more activity firing up this morning, but isolated in
nature that could affect more of the CWA. Will have to keep an eye
on radar this morning. For now just have mention in far eastern
counties through 14z.
Byrd
&&
.SHORT TERM: (Through Late This Afternoon)
Issued at 326 AM CDT Mon Sep 9 2013
Front to continue moving back north as a warm front this morning,
so the above normal weather to persist through the next several
days. However, there is some residual mid clouds from weak
shortwave that is sliding through the area early this morning. As
for chances of isolated showers with this shortwave, feel that
they will develop just south of forecast area today, so kept
forecast dry for now. Otherwise, these clouds should clear out
from northwest to southeast today. So with 850 temps aoa 22C over
the central plains, will see high temps in the 90s with the
warmest temps over northern MO, while southeast MO/southern IL to
be a bit slower in its warm up due to the lingering mid clouds.
Despite dewpts mixing out by this afternoon and lowering into the
low to mid 60s, heat index values in northeast MO/west central IL
will approach 100.
Byrd
.LONG TERM: (Tonight through Sunday)
Issued at 326 AM CDT Mon Sep 9 2013
Another very mild night tonight with lows only in the upper 60s
to mid 70s. Hot and humid weather to persist on Tuesday with highs
in the mid to upper 90s with lows Tuesday night in the upper 60s
to low 70s. With highs in the mid to upper 90s both today and
Tuesday, could be close to record highs for this time of year.
Wednesday to remain another above normal day, though a few degrees
cooler as cu pop up ahead of next frontal boundary. Models are a bit
slower with this front now, but should still see it move into the
forecast area Wednesday night. Still not a lot of pcpn expected with
this boundary, so just kept low chance pops for far northern
counties on Wednesday, then spread chance pops south across most of
forecast area Wednesday night.
Beyond that, front to slide south of forecast area during the day
Thursday with surface ridge building in. This will bring in cooler
and drier conditions for the rest of the forecast period. Highs will
be in the mid to upper 80s on Thursday, then drop into the mid 70s
to mid 80s for the remainder of the forecast period. Lows will be in
the 50s over the weekend.
Byrd
&&
.AVIATION: (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1103 AM CDT Mon Sep 9 2013
VFR through the period with southwesterly winds. Some light fog is
possible in favored valley locations tonight if the winds become
calm.
Specifics for KSTL: VFR through the period with southwesterly
winds.
Kanofsky
&&
.CLIMATE:
ISSUED AT 306 PM CDT SAT SEP 7 2013
RECORD HIGHS:
SEPT 9 SEPT 10
STL 101/1925 98/1983
COU 99/1925 99/1938
UIN 100/1945 100/1933
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
1024 AM PDT MON SEP 9 2013
.SYNOPSIS....SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ACROSS MUCH
OF THE AREA THROUGH WEDNESDAY WITH A DRYING TREND ON THE HORIZON FOR
THE LATTER PART OF THE WEEK. TEMPERATURES TO REMAIN BELOW NORMAL
THROUGH MID WEEK THEN WARM BACK TO NEAR OR SLIGHTLY ABOVE NORMAL AS
THE WEEKEND APPROACHES.
&&
.UPDATE...SCATTERED LIGHT SHOWERS MOVED ACROSS THE SOUTH END OF THE
LAS VEGAS VALLEY EARLIER THIS MORNING BRINGING MEASURABLE RAIN TO
SOME NEIGHBORHOODS. THESE HAVE SINCE MOVED OUT. LOOKING AHEAD TO
THIS AFTERNOON THE MOST ACTIVE AREAS LOOK TO BE MOHAVE AND EASTERN
SAN BERNARDINO COUNTIES INITIALLY. MOHAVE COUNTY HAS HAD QUITE A BIT
OF SUNSHINE THIS MORNING WHICH SHOULD HELP TO DESTABILIZE THE
ATMOSPHERE AND TRIGGER CONVECTION. ACROSS EASTERN SAN BERNARDINO
COUNTY COULD MID-LEVEL CONVERGENCE ON THE BACK SIDE OF THE MID/UPPER
LEVEL LOW IS SHOWN IN THE MODELS WHICH SHOULD HELP TO FORCE
CONVECTION HERE. THE HRRR MODEL CONFIRMS THESE AS BEING THE MOST
ACTIVE SPOTS THIS AFTERNOON AND WHERE WE MAY SEE THE FIRST ISSUES
WITH ANY HEAVIER STORMS FOR FLASH FLOODING. I CONSIDERED GOING WITH
A WATCH FOR THESE AREAS BUT THE COVERAGE OF HEAVIER STORMS IS STILL
QUESTIONABLE AT THIS TIME.
LOOKING AHEAD TO THIS EVENING, WE HAVE A NORTHEAST STEERING FLOW IN
PLACE ACROSS CLARK COUNTY COURTESY OF THE MID/UPPER LEVEL LOW TO OUR
SOUTH. THIS HAS BEEN A PATTERN IN THE PAST THAT HAS PRODUCED SOME
SIGNIFICANT STORMS FOR LAS VEGAS INCLUDING THE JULY 18 1994 HILTON
SIGN THUNDERSTORM EVENT AND MORE RECENTLY THE JULY 19TH EVENT THIS
YEAR. THE HRRR MODEL AS WELL AS THE NMM SURFACE WINDS AND WRF MODEL
QPF ALL HINT AT THE POTENTIAL FOR EITHER AN OUTFLOW BOUNDARY OR
CONVECTION TO MOVE IN FROM THE NORTHEAST THIS EVENING BETWEEN 6 AND
10 PM INTO NORTHEAST CLARK COUNTY AND EVENTUALLY LAS VEGAS. I DID GO
AHEAD AND ADJUST UP POPS IN THESE AREAS BY 10-15 PERCENT TO ACCOUNT
FOR THIS. STILL SOME UNCERTAINTY WITH THIS...BUT IT WILL BE WORTH
SEEING HOW THINGS PROGRESS AS TODAY UNFOLDS.
&&
.AVIATION...FOR MCCARRAN...GENERALLY LIGHT WINDS FROM THE EAST TO
SOUTHEAST TO CONTINUE TODAY WITH SPEEDS EXPECTED TO BE LESS THAN 9
KTS. SCATTERED THUNDERSTORMS ARE EXPECTED OVER THE SPRING MOUNTAINS
THIS AFTERNOON. THE WEATHER PATTERN IS FAVORABLE FOR A CHANCE OF
LATE EVENING THUNDERSTORMS COMING DOWN THE MORMON MESA CORRIDOR INTO
THE LAS VEGAS VALLEY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SCATTERED SHOWERS AND THUNDERSTORMS REDEVELOP THIS
AFTERNOON ACROSS MUCH OF THE AREA. SCT-BKN CLOUDS GENERALLY 10-15K
FEET TODAY IN THE EAST AND SOUTH WITH SKC-FEW CLOUDS AROUND 15K FEET
WEST. PREVAILING WINDS OUTSIDE OF STORM INFLUENCES SHOULD GENERALLY
REMAIN UNDER 10 KTS.
&&
.PREVIOUS DISCUSSION...
ISSUED AT 228 AM PDT MON SEP 9 2013
.SHORT TERM...THROUGH TUESDAY NIGHT...SATELLITE IMAGERY CLEARLY
SHOWS A CLOSED LOW CIRCULATING OVER FAR SOUTHERN NEVADA ENHANCING
CLOUD COVER AND SHOWERS TO ITS NORTH. AT 1 AM...RADAR WAS SHOWING
ENHANCED SHOWER ACTIVITY TO THE EAST OF LAS VEGAS MOVING WEST. BASED
ON THE PLACEMENT OF THIS WELL DEVELOPED CIRCULATION...THE VALLEY
STANDS A DECENT CHANCE OF SEEING RAIN SHOWERS OVER THE NEXT FEW
HOURS.
THE CIRCULATION IS FORECAST TO REMAIN NEARLY STATIONARY THROUGH THE
DAY WITH A DEFORMATION AXIS FORECAST NEAR THE MOHAVE/CLARK COUNTY
BORDER. MOISTURE/INSTABILITY PARAMETERS POINT TO CENTRAL AND EASTERN
SAN BERNARDINO...CLARK AND MOHAVE COUNTIES AS THE PRIMARY LOCATIONS
FOR STORM DEVELOPMENT TODAY. WITH CLOUD COVER FORECAST TO THIN OR
DISSOLVE ACROSS THE WEST AND REMAIN PARTLY TO MOSTLY CLOUDY IN THE
EAST...DIFFERENTIAL HEATING WILL LIKELY PLAY A ROLE ALONG THIS
BOUNDARY TO HELP INITIATE AND FOCUS STORMS IN ADDITION TO THE
DYNAMICS PROVIDED BY THE CLOSED CIRCULATION. THERE ARE TOO MANY
VARIABLES IN PLAY TO PINPOINT THE EXACT LOCATION OF THE MOISTURE
BOUNDARY AND WHERE THE STRONGEST STORMS WILL FORM BUT LOCALIZED
FLASH FLOODING IS CERTAINLY A POSSIBILITY AGAIN TODAY.
HEADING INTO TUESDAY...BROAD LOW PRESSURE IS FORECAST OVER THE CWA
WITH ANY NUMBER OF MESO SCALE CIRCULATIONS POSSIBLE. EASTERN SAN
BERN...CLARK...LINCOLN AND MOHAVE COUNTIES APPEAR TO BE THE PRIMARY
FOCUSING AREA FOR THUNDERSTORM DEVELOPMENT. TEMPERATURES WILL REMAIN
WELL BELOW NORMAL TODAY AND TUESDAY.
.LONG TERM...WEDNESDAY THROUGH MONDAY. THE MODELS HAVE COME INTO A
LITTLE BETTER AGREEMENT ON A DRYING TREND FROM SOUTHWEST TO
NORTHEAST THURSDAY THROUGH SATURDAY. FOR WEDNESDAY...WEAK UPPER LOW
OVER THE SOUTHWEST WILL KEEP THE AIRMASS WEAKLY UNSTABLE...AND WITH
PLENTY OF TROPICAL MOISTURE STILL IN PLACE...CHANCES FOR
THUNDERSTORMS WILL PERSIST OVER MUCH OF THE AREA WITH THE BEST
CHANCES IN THE EASTERN CWA. BEGINNING THURSDAY...THE UPPER LOW
SLOWLY LIFTS OUT TO THE NORTHEAST AS HIGH PRESSURE STARTS TO NOSE IN
FROM THE SOUTHWEST. THERE IS STILL SOME SPREAD AMONG THE ENSEMBLES
WITH RESPECT TO HOW QUICKLY THIS PATTERN CHANGE TAKES PLACE...BUT
CONFIDENCE IS INCREASING IN THE EXISTENCE OF THE PATTERN CHANGE. MOS
GUIDANCE NOW SHOW SURFACE DEWPOINTS IN THE 20S NORTHWEST AND
30S/40S SOUTHEAST BY SUNDAY...WHICH WOULD BE ABOUT A 30 DEGREE DROP
IN THE SOUTHEAST CWA FROM CONDITIONS OF THE PAST FEW WEEKS. AS THE
DRIER AIR MOVES IN...TEMPERATURES WILL RISE A FEW DEGREES...AND
COULD BE NEARING 100 DEGREES IN LAS VEGAS OVER THE WEEKEND.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&
$$
UPDATE...STACHELSKI
AVIATION...ADAIR
PREVIOUS...SALMEN/MORGAN
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
316 PM EDT MON SEP 9 2013
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST INTO MID WEEK AND THEN MOVE OFFSHORE.
A COLD FRONT IS EXPECTED TO CROSS THE AREA ON FRIDAY. HIGH
PRESSURE AND COOLER TEMPERATURES WILL FOLLOW FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM MONDAY...BEAUTIFUL AFTERNOON ONGOING ACROSS THE
CAROLINAS THANKS TO AN AREA OF HIGH PRESSURE CENTERED NEAR NEW
ENGLAND...RIDGING DOWN THE EAST COAST. TEMPS HAVE RISEN INTO THE
MID/UPR 80S...WHICH COMBINED WITH DEWPOINTS IN THE UPPER 60S HAS
SPAWNED SOME AGITATED CU...FROM WHICH A FEW ISOLATED SHOWERS HAVE
DEVELOPED. SHOWERS HAVE BEEN CONFINED TO THE WESTWARD MOVING SEA
BREEZE BOUNDARY...AND HAVE CONTINUED SCHC POP ALONG THIS BOUNDARY
FOR A FEW MORE HOURS BEFORE LOSS OF DIURNAL HEATING CAUSES ANY
CONVECTION TO CEASE. AS EXPECTED...NO LIGHTNING HAS DEVELOPED DUE TO
OVERALL WEAK UPDRAFTS BEING CAPPED BY A BULGING THERMAL INVERSION
AROUND 750MB NOTED ON RUC PROXIMITY SOUNDINGS (IN RESPONSE TO
MID-LEVEL RIDGING EXPANDING TO THE WEST)...AND HAVE KEPT RW- AS THE
WX TYPE THROUGH TONIGHT.
CLOUD COVER AND SHOWERS WILL DISSIPATE QUICKLY AFTER
NIGHTFALL...ALLOWING FOR VERY GOOD RADIATIONAL COOLING TONIGHT...AND
TEMPS WILL FALL RAPIDLY AFTER DARK. AS TEMPS FALL TONIGHT...CONCERN
BECOMES HOW COOL WILL THE AREA GET...AND WHAT FOG POTENTIAL EXISTS.
WITH QUICKLY FALLING TEMPS BENEATH THE DRY COLUMN...AND WINDS LIKELY
DECOUPLING...HAVE SHOWN SOME RADIATIONAL COOLING EFFECT IN THE MIN-T
FORECAST AND HAVE UNDERCUT MOS NUMBERS TONIGHT...WITH LOW-TO-MID 60S
EXPECTED. SOME TEMPS NEAR 60 ARE POSSIBLE IN THE TYPICALLY COOLER
LOCATIONS.
AS TEMPS FALL TO THESE VALUES TONIGHT...THEY WILL EXCEED THE
CROSSOVER TEMPS...A SIGNAL NORMALLY ASSOCIATED WITH FOG POTENTIAL.
AT THE SAME TIME...RUC AND NAM BUFR SOUNDINGS SHOW FAVORABLE
LOW-LEVEL HYDROLAPSE RATES FOR FOG DEVELOPMENT...ESPECIALLY INLAND
FROM THE COAST. HAVE ADDED PATCHY/AREAS OF FOG INLAND...WHERE FOG IS
MORE LIKELY. THE COAST MAY EXPERIENCE SOME FOG AS WELL...BUT IT WILL
NOT BE AS WIDESPREAD OR DENSE AS WHAT IS EXPECTED ACROSS THE
CENTRAL/WESTERN PORTIONS OF THE CWA.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...HIGH PRESSURE ALOFT WILL REMAIN IN PLACE ON
TUESDAY. AT THE SURFACE...ATLANTIC HIGH PRESSURE WILL BE CENTERED
SOUTH OF THE CANADIAN MARITIMES AND RIDGE SW AND ALL THE WAY BACK
ACROSS THE EASTERN CAROLINAS. ON WED...THE SURFACE RIDGE WILL
BEGIN TO WEAKEN ACROSS THE SOUTHEAST UNITED STATES. THE LARGE
AREA OF HIGH PRESSURE ALOFT WILL SPLIT...TO OUR W AND TO OUR E.
THIS WILL ALLOW A TROUGH TO EVENTUALLY DIG ACROSS THE EASTERN
THIRD OF THE NATION LATE WEEK.
THE PERIOD LOOKS LIKE IT WILL BE DRY AS SUBSIDENCE AND DRY AIR...
ESPECIALLY IN THE MID LEVELS...DOMINATE. DO EXPECT SCATTERED TO
BRIEFLY BROKEN CUMULUS TO BUILD UP EACH AFTERNOON...BUT THIS
MOISTURE WILL BE CAPPED BELOW 10 KFT...KEEPING ANY BUILDUPS RATHER
SHALLOW. DAYTIME TEMPS WILL BE SLIGHTLY ABOVE NORMAL...COMMONLY IN
THE UPPER 80S TO LOWER 90S. THE SEABREEZE IS EXPECTED TO MAKE
GOOD INLAND PROGRESS GIVEN THE DEEP SYNOPTIC EASTERLY FLOW. THIS
WILL REDUCE HIGHS ALONG AND NEAR THE COAST BY ABOUT A CATEGORY AS
COMPARED TO LOCATIONS MUCH FURTHER INLAND. LOW TEMPS WILL BE
RATHER TYPICAL FOR MID SEPTEMBER...UPPER 60S AND LOWER 70S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...A RELATIVELY FAST MOVING/PROGRESSIVE TROUGH
WILL BE THE MAIN FEATURE FOR THE EXTENDED PERIOD OF THE FORECAST.
MEDIUM RANGE GUIDANCE HAS INCREASED THE TIMING FOR THE ASSOCIATED
FRONT WHICH NOW APPEARS TO MOVE ACROSS THE AREA FRIDAY MORNING.
THE LATEST UPDATE INCLUDES AN INCREASE OF POPS FOR THE THURSDAY
NIGHT/FRIDAY MORNING TIME PERIOD WITH A SLIGHT DOWNTREND FOR
FRIDAY`S POPS. IT APPEARS GUIDANCE IS ALSO CONVERGING ON A
SOLUTION OF A MORE SOUTHERN EXTENT OF THE FRONT FOR THE WEEKEND
INTO EARLY NEXT WEEK...SETTING UP A COOL AND DRY WEEKEND. DO NOT
EXPECT IDEAL RADIATIONAL CONDITIONS FOR ANY OVERNIGHT PERIOD BUT
SUNDAY MORNING APPEARS TO BE THE COOLEST WITH THE LIGHTEST WINDS.
WE HAVE LOWS IN THE LOWER 50S EXTREME NORTHWESTERN AREAS WITH NEAR
60 ALONG THE COAST. MOST HIGHS WILL BE IN THE UPPER 70S TO LOWER
80S FOR THE WEEKEND.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 18Z...VFR CONDITIONS WILL PREVAIL THIS AFTN WITH SOUTHEAST
WINDS AOB 10 KTS. DRY AIR ALOFT WILL INHIBIT MUCH CONVECTIVE
ACTIVITY TODAY...BUT ANY SHOWER ACTIVITY DOES NOT EVEN WARRANT A
VCSH MENTION WITHIN TAF. CLOUD COVER WILL BE COMPRISED OF SCT TO AT
TIMES BKN CU...BUT AT VFR HEIGHTS. CLEAR SKIES AND CALM/LIGHT WINDS
OVERNIGHT WILL BE CONDUCIVE FOR FOG EARLY TUESDAY...ESPECIALLY
INLAND. FCST SOUNDINGS AND GUIDANCE SUPPORT MVFR/TEMPO IFR VSBYS AT
KFLO/KLBT BETWEEN 09-12Z. DENSE FOG SEEMS LESS LIKELY ALONG THE
COAST...BUT TEMPO MVFR VSBYS ARE CERTAINLY POSSIBLE AROUND DAYBREAK.
ONCE THE FOG DISSIPATES...EXPECT VFR DURING THE DAY SATURDAY WITH
NORTHEAST WINDS 5-8 KTS.
EXTENDED OUTLOOK...EARLY MORNING MVFR/IFR VSBYS POSSIBLE THROUGH
THURSDAY...MOST LIKELY AT KFLO/KLBT. CHANCE OF SHOWERS/T-STORMS ON
FRIDAY ASSOCIATED WITH A COLD FRONT. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM MONDAY...HIGH PRESSURE CENTERED ACROSS NEW ENGLAND IS
RIDGING DOWN THE COAST TODAY...WHICH HAS KEPT A WEAK PRESSURE
GRADIENT ACROSS THE WATERS. WINDS HAVE BEEN QUITE LIGHT IN RESPONSE
TO THIS GRADIENT...10 KTS OR LESS AT THE LOCAL BUOYS...AND THESE
SPEEDS WILL PERSIST TONIGHT EVEN AS DIRECTION BACKS MORE TO THE NE.
THE SEA SPECTRUM WILL REMAIN COMPRISED OF A LOW-AMPLITUDE E/NE WIND
CHOP AND A 2 FT SE SWELL...CREATING WAVE HEIGHTS OF 2-3 FT THROUGH
TONIGHT...BUT ONLY AROUND 1-2 FT NEAR SHORE OF BRUNSWICK COUNTY DUE
TO WAVE SHADOWING.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...HIGH PRESSURE WILL BE CENTERED WELL N OF THE
WATERS THROUGH THE PERIOD. WINDS WILL STILL BE FROM THE NE ON
TUE...VEERING SLIGHTLY TO ENE OR E TUE AFTERNOON AND EVE AND THEN
BACK TO A MORE NE DIRECTION OVERNIGHT TUE. NE WINDS WED MORNING
WILL VEER TO E OR ESE DURING THE DAY...BECOMING LIGHT AND VARIABLE
WED NIGHT. THE GRADIENT WILL BE TIGHTEST ON TUE...SUSTAINED WIND
SPEEDS UP TO 15 KT. THEREAFTER...WINDS WILL BE 10 KT OR LESS. WIND
SPEEDS WILL BE COMPARATIVELY HIGHER ACROSS THE NEAR SHORE WATERS
EACH AFTERNOON DUE TO SEABREEZE INFLUENCES. SEAS WILL BE 2 TO 3
FT...BUT THERE WILL BE SOME 4 FT SEAS TUE AFTERNOON WHEN THE
GRADIENT IS EXPECTED TO BE TIGHTEST.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 3 PM MONDAY...THE MAIN FEATURE WILL BE THE WIND SHIFT
ASSOCIATED WITH THE FRONT MOVING ACROSS THE WATERS FRIDAY MORNING.
WINDS WILL SHIFT FROM A MODEST PRE-FRONTAL SOUTHWESTERLY FLOW OF
10-15 KNOTS...MOSTLY HOVERING AROUND THE LOWER END OF THE RANGE TO
NORTH/NORTHEAST BY MIDDAY FRIDAY. SPEEDS WILL INCREASE TO REACH A
MAX OF 15-20 KNOTS EARLY SATURDAY. THE NORTHEASTERLY FLOW WILL BE
RELATIVELY STABLE AT 15-20 KNOTS FOR THE REMAINDER OF SATURDAY BUT
SPEEDS MAY DIMINISH TOWARD THE LOWER END OF THE RANGE. SIGNIFICANT
SEAS WILL INCREASE FROM 1-2 FEET EARLY TO 2-4 FEET BY THE END OF THE
PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...JDW
SHORT TERM...RJD
LONG TERM...SHK
AVIATION...BJR/JDW
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
145 PM EDT MON SEP 9 2013
.SYNOPSIS...
HIGH PRESSURE WILL EXTEND OVER THE AREA FROM THE NORTHEAST THROUGH
MIDWEEK. A COLD FRONT WILL MOVE THROUGH THE AREA EARLY FRIDAY. COOL
HIGH PRESSURE WILL BE OVER THE AREA FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 130 PM MONDAY...DROPPED POPS OVER SRN COASTAL SECTIONS AS
ACTIVITY JUST OFFSHORE HAS DISSIPATED. NO OTHER CHANGES.
/PREVIOUS DISCUSSION/
AS OF 645 AM MONDAY...COLD FRONT CONTINUES TO MAKE SLOW PROGRESS
INTO NORTHEASTERN NORTH CAROLINA AND SHOULD BE NEAR OR JUST SOUTH
OF OUR COAST BY 12Z TO 14Z THIS MORNING WITH WINDS BECOMING NE
THEN GRADUALLY E LATER IN THE DAY AS HIGH PRESSURE DRIFTS
OFFSHORE. SATELLITE IMAGERY SHOWING LOW CLOUDS BEHIND THE FRONT
OVER VIRGINIA BUT FEEL SKIES WILL BE PARTLY CLOUDY OVER OUR
REGION ALLOWING TEMPERATURES TO APPROACH FORECAST MAX TEMPS IN THE
MID TO UPPER 80S IN MOST AREAS. THE 3 KM HRRR AND 4 KM WRF STILL
SHOW SOME ISOLATED SHOWERS ALONG THE SEA BREEZE IN THE AFTERNOON
BUT WITH LARGE SCALE SUBSIDENCE AND STRONG NVA OVER EASTERN
NC...WILL CONTINUE TO LEAVE POPS OUT OF THE FORECAST FOR TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
AS OF 340 AM MONDAY...THE LOW-LEVEL FLOW TONIGHT WILL BECOME LIGHT
AND ONSHORE. THIS WILL INCREASE BOUNDARY LAYER MOISTURE AND THERE
WILL AGAIN BE A GOOD LIKELYHOOD OF SOME LOWER STRATUS AND FOG
TOWARD MORNING. MINIMUM TEMPERATURES WILL BE FAIRLY SIMILAR TO
THIS MORNING WITH LOWS IN THE 66 TO 72 RANGE IN MOST AREAS.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 330 AM MON...THE LONG TERM PERIOD WILL FEATURE DRY AND WARM
WEATHER THROUGH THURSDAY...FOLLOWED BY A STRONG COLD FRONTAL
PASSAGE AND INCREASING PRECIP CHANCES THURSDAY NIGHT INTO
FRIDAY...THEN MUCH DRIER AND COOLER WEATHER FOR NEXT WEEKEND.
TEMPS WILL EDGE ABOVE CLIMO DURING THE MID WEEK TIME PERIOD WHILE
CONDITIONS REMAIN DRY WITH WESTERN ATLANTIC RIDGE CONTINUING TO
DOMINATE THE AREA. DEWPOINTS WILL BE ON THE INCREASE AS WELL WITH
TEMPS EDGING UPWARDS DURING THE OVERNIGHT PERIOD...THOUGH LOWS WILL
REMAIN NEAR CLIMO FOR EARLY SEPTEMBER. MED/LONG RANGE MODELS
CONVERGING ON STRONG SHORTWAVE TROUGH/SFC COLD FRONT TO AFFECT THE
AREA BEGINNING THURSDAY NIGHT. SW FLOW WILL INC ON THUR WITH TEMPS
REACHING INTO THE LOW 90S WITH TD`S INTO THE LOW 70S. ANY PRECIP
WILL REMAIN WELL WEST OF THE AREA THUR AFTERNOON WITH UPPER SUPPORT
IN THE APPALACHIANS. MODELS HAVE COME IN JUST A BIT FASTER WITH
FRONTAL PASSAGE...DURING THE DAY FRIDAY...THOUGH LAST SEVERAL RUNS
OF ECMWF HAVE COME IN DRIER THAN THE GFS WITH BULK OF UPPER SUPPORT
SHUNTING NORTH OF NC THROUGH THE MID ATLANTIC REGION. HAVE EDGED
POPS DOWNWARD TO 30-40 PERCENT TO REFLECT THE POSSIBLE DRIER FRONTAL
PASSAGE...AND MAY HAVE TO DECREASE FURTHER IF THIS TREND CONTINUES.
STRONG COOL AND DRY HIGH PRES WILL BUILD INTO THE AREA FROM THE NW
NEXT WEEKEND WITH TEMPS EXPECTED BELOW CLIMO ALONG WITH MUCH LOWER
RELATIVE HUMIDITY VALS.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
SHORT TERM /THROUGH 18Z TUESDAY/...
AS OF 130 PM MONDAY...VFR CONDITIONS WILL PREVAIL THROUGH EVENING
WITH SOME FAIR WX CU THIS AFTN. IFR TO LIFR VSBYS LIKELY AGAIN LATE
TONIGHT ALL TAF SITES WITH ALL MODEL GDNC SUPPORTING FOG
DEVELOPMENT. CONDITIONS IMPROVING TO FAIR WX VFR 13Z-14Z TUESDAY.
LONG TERM /TUE THROUGH FRI/...
AS OF 330 AM MON...MAINLY VFR CONDITIONS THROUGH THE LONG TERM
PERIOD...WITH THE EXCEPTION OF LATE NIGHT/EARLY AM RADIATION FOG.
HIGH PRES WILL DOMINATE THROUGH THURSDAY...FOLLOWED BY A STRONG
COLD FRONT PUSHING THROUGH LATE THURSDAY NIGHT INTO FRIDAY. A
SMALL CHANCE OF PRECIP WILL ACCOMPANY THE FRONTAL PASSAGE. STRONG
DRY HIGH PRES WILL BUILD IN FOR NEXT WEEKEND.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 130 PM MONDAY...DECREASED SHOWER COVERAGE TO ISOLATED FOR SRN
WATERS REST OF AFTN. NO OTHER SIGNIFICANT CHANGES TO FCST.
/PREVIOUS DISCUSSION/
AS OF 655 AM MONDAY...WINDS HAVE BECOME NE OVER THE FAR NORTHERN
WATERS AND SHOULD GRADUALLY VEER FROM SW/W AROUND TO N/NE OVER THE
NEXT 3 OR 4 HOURS OVER ALL WATERS AND SOUNDS. GIVEN SOME GUSTS
INTO THE HIGH TEENS OVER THE HAMPTON ROADS AREA OF VIRGINIA
FOLLOWING THE FRONTAL PASSAGE...HAVE BUMPED WINDS INTO THE 10 TO
15 KNOT RANGE OVER ALL WATERS AND WOULD NOT BE SURPRISED TO SEE A
FEW GUSTS APPROACHING 20 KNOTS THIS MORNING BEFORE SUBSIDING THIS
AFTERNOON AS THE HIGH MOVES OFFSHORE. SEAS SHOULD REMAIN IN THE 2
TO 4 FOOT RANGE. LOCAL NWPS MODEL SHOWS SEAS BUILDING TO AROUND 4
FEET OVER THE CENTRAL AND NORTHERN WATERS TONIGHT AS THE HIGH
MOVES OFFSHORE AND MORE SE SWELL ENERGY DEVELOPS.
LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 330 AM MON...WINDS WILL GRADUALLY VEER TO THE E AND SE TUE
INTO WED WITH SPEEDS 10 KT OR LESS AS THE SFC RIDGE EXTENDS OVER
AREA FROM E-NE. FLOW WILL INCREASE A BIT FROM THE SW LATE THU AHEAD
OF THE NEXT APPROACHING COLD FRONT. POTENTIAL FOR SCA CONDITIONS FRI
INTO THE WEEKEND AS STRONG HIGH PRES BUILDS IN FROM THE NW WITH COLD
AIR ADVECTION OVER THE WATERS AND TIGHTENING NE GRADIENT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JBM
NEAR TERM...JBM/CTC
SHORT TERM...CTC
LONG TERM...TL
AVIATION...JBM/TL
MARINE...CTC/TL/JBM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
123 PM CDT MON SEP 9 2013
.UPDATE...
ISSUED AT 123 PM CDT MON SEP 9 2013
UPDATED MAINLY FOR CLEANING UP POPS AND SKY COVER. SHOWERS
CONTINUE TO MOVE OUT OF CENTRAL INTO EASTERN NORTH DAKOTA WITH A
DIMINISHING TREND. SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING
IN NORTHEAST MONTANA ARE ABOUT TO MOVE INTO THE FAR NORTHWEST.
TEMPERATURES APPEAR IN LINE FOR AFTERNOON HIGHS.
UPDATE ISSUED AT 1017 AM CDT MON SEP 9 2013
UPDATE THIS MORNING DEALT MAINLY WITH ADJUSTING CLOUDS AND POPS TO
CURRENT RADAR AND SATELLITE IMAGERY. CLEARING OUT ACROSS THE
SOUTHWEST...BUT SHOWERS CONTINUE OVER THE NORTH CENTRAL ON THE
BACK SIDE OF THE SURFACE LOW OVER SOUTHEAST NORTH DAKOTA.
UPDATE ISSUED AT 644 AM CDT MON SEP 9 2013
THE LATEST RADAR TRENDS AND 3KM HRRR INDICATE DECREASING
PRECIPITATION INTENSITY ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
EVEN THOUGH COPIOUS AMOUNTS OF MOISTURE ARE OVER THE AREA...THE
ATMOSPHERE IS PRETTY WELL WORKED OVER FOR ANY STORMS TO GROW
UPSCALE THIS MORNING. AS A RESULT...DECIDED TO CANCEL THE FLASH
FLOOD WATCH ACROSS THE ENTIRE CWA THIS MORNING.
AN UPPER LEVEL LOW CURRENTLY SITUATED OVER NORTH CENTRAL MONTANA
IS FORECAST TO PIVOT INTO NORTHWESTERN NORTH DAKOTA LATER THIS
AFTERNOON. THIS COMBINED WITH INCREASING UPPER LEVEL DYNAMICS MAY
ALLOW THUNDERSTORMS TO DEVELOP AND BECOME SEVERE...MAINLY NORTH
OF I-94 LATER THIS AFTERNOON AND EVENING. THE DAY 1 SPC OUTLOOK
HAS NORTHERN NORTH DAKOTA IN A "SEE TEXT" CATEGORY AND A 5% CHANCE
OF DAMAGING WINDS AND HAIL. AS A RESULT...HIGHLIGHTED THIS THREAT
IN THE HWO. HOWEVER...KEPT IT OUT OF THE ZONES DUE TO ITS LOW
PROBABILITY.
THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 452 AM CDT MON SEP 9 2013
THE SEVERE THREAT HAS ENDED ACROSS THE JAMES RIVER BASIN. AS A
RESULT...CANCELLED THE SEVERE THUNDERSTORM WATCH FOR THE AFFECTED
AREAS. OTHERWISE...ONLY MODIFIED THE REMAINING WEATHER ELEMENTS
BASED ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT MON SEP 9 2013
IN THE NEAR TERM...THE SEVERE WEATHER THREAT IS LIKELY OVER AS THE
BOW ECHO HAS PUSHED EAST OF THE FORECAST AREA. HEAVY RAIN THREAT
WILL PERSIST...MAINLY IN THE JAMES RIVER VALLEY THIS MORNING. SEE
HYDRO DISCUSSION BELOW FOR DETAILS. MUCH OF THE FORECAST AREA IS
MENTIONED IN THE SEE TEXT AREA OF THE SPC DAY 1 OUTLOOK. ISOLD
LARGE HAIL/WIND GUSTS NOT OUT OF THE QUESTION THIS
AFTERNOON/EVENING. WITH THE 500MB COLD POOL MOVING INTO THE NORTH
THIS AFTERNOON...WILL ALSO HAVE TO MONITOR FOR POTENTIAL
FUNNELS/BRIEF NON-SUPERCELL TORNADOES.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 350 AM CDT MON SEP 9 2013
QUIET WEATHER WILL CONTINUE FOR MUCH OF THE LONG TERM PERIOD. THE
MAIN WINDOW FOR THUNDERSTORM ACTIVITY WILL BE FRIDAY
NIGHT/SATURDAY. OTHERWISE...EXPECT MILDER TEMPS WITH HIGHS
GENERALLY IN THE 70S TO LOWER 80S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 123 PM CDT MON SEP 9 2013
MVFR CEILINGS THIS AFTERNOON WILL SLOWLY LIFT THROUGH 23 UTC. THEN
VFR CEILINGS EXPECTED UNTIL AROUND 06Z AS AREAS OF MVFR CEILINGS
ARE EXPECTED TO DROP SOUTHEAST ACROSS THE AREA BEHIND THE UPPER
LEVEL LOW THAT TRACKS EAST ACROSS NORTHERN NORTH DAKOTA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...RK
LONG TERM...RK
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
140 PM EDT MON SEP 9 2013
.SYNOPSIS...
AN AREA OF HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES
WILL MOVE OFF THE NEW ENGLAND COAST TODAY. THIS WILL ALLOW A WARM
FRONT TO LIFT NORTHEAST ACROSS THE LOCAL AREA. AN AREA OF LOW
PRESSURE WILL PASS WELL TO THE NORTH ON WEDNESDAY AND DRAG A COLD
FRONT ACROSS THE REGION ON WEDNESDAY NIGHT. HIGH PRESSURE WILL
RETURN FOR THE END OF THE WORKWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
TWEAKED TEMPS UP A LITTLE IN THE EAST...OTHERWISE FORECAST LOOKS
GOOD.
ORIGINAL...QUITE A BIT OF SHOWER AND THUNDERSTORM ACTIVITY OVER SW LOWER
MICHIGAN. THIS ACTIVITY HAS FORMED ALONG A WARM FRONT THAT WILL
LIFT NE ACROSS THE LOCAL AREA TODAY. ALL OF THE NEW
GUIDANCE...INCLUDING THE HRRR AND CONVECTIVE SREF SHOW AT LEAST
SCATTERED PRECIP. HAVE BUMPED PRECIP CHANCES UP ALL AREAS TO
AROUND 40 PERCENT. MAY EVENTUALLY HAVE TO BUMP IT EVER FURTHER
DEPENDING ON WHAT THE ACTIVITY OVER MI DOES. DEWPOINTS ARE ALREADY ON
THE WAY UP AND EXPECTING MID 60S BY EARLY EVENING. THERE SHOULD
BE A LOT OF CLOUDINESS TODAY BUT TEMPS WILL STILL MAKE THE 80S
OVER ALL BUT THE EASTERN END OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
THE WARM FRONT WILL MOVE NORTH OF LAKE ERIE THIS EVENING AND THAT
SHOULD END THE THREAT FOR ADDITIONAL PRECIP. WILL START THE
TONIGHT PERIOD OUT WITH SMALL POPS...ESPECIALLY ACROSS NW PA. THE
REMAINDER OF THE NIGHT AND TUESDAY SHOULD BE DRY. MODELS STILL
PUSHING 850 MB TEMPS TO PLUS 20 OR WARMER ON TUESDAY. NEW GUIDANCE
IS A TAD COOLER WITH HIGHS BUT HAVE NOT MADE ANY SIGNIFICANT
CHANGES. MUCH OF THE AREA SHOULD REACH THE 90 DEGREE MARK. THE
WARM AND HUMID AIR MASS WILL REMAIN IN PLACE ON WEDNESDAY AS WELL.
THERE SHOULD BE MORE CLOUDS AND INCREASING CHANCES FOR PRECIP.
THIS WILL HOLD TEMPS BACK A LITTLE. IT APPEARS THAT THE BEST
CHANCES FOR CONVECTION DURING THE PERIOD WILL COME WEDNESDAY
EVENING AND NIGHT AS THE COLD FRONT FINALLY ARRIVES. HAVE GIVEN
MUCH OF THE AREA LIKELY POPS. THERE WILL BE A DISTINCT AIR MASS
CHANGE BEHIND THE FRONT. STRONG COLD AIR ADVECTION IS EXPECTED
BEHIND THE FRONT ON THURSDAY. THE MODELS TRY TO DRY THINGS OUT
QUICKLY BUT SUSPECT THAT THIS IS TOO FAST. WILL LIKELY SEE A FAIR
AMOUNT OF CLOUDINESS AND PERHAPS A FEW SHOWERS DOWN WIND OF THE
LAKE. AFTER TUESDAY HAVE USED A BLEND OF GUIDANCE TEMPS.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
TROUGH ALOFT FRIDAY WITH A VERY COOL AIR MASS. STILL GOOD CONSENSUS
THAT H8 TEMPS WILL BE BETWEEN +2C AND +5C. WILL KEEP THE HIGHS IN
THE 60S BOTH FRIDAY AND SATURDAY...WITH EVEN SOME UPPER 50S ACROSS
NW PA ON FRIDAY. FAIRLY CLOUDY TO START FRIDAY WITH ADDITIONAL LAKE
CLOUDS...BUT BY LATE AFTERNOON HIGH PRESSURE FROM THE CENTRAL LAKES
REALLY BEGINS TO BUILD IN. WILL ALSO KEEP SOME LOW PRECIP CHANCES
FOR LAKE EFFECT RAIN SHOWERS. SIGNIFICANT DRYING AND RIDGING BEGIN
TO WORK IN FOR SATURDAY...SO PRECIP SHOULD NOT BE A PROBLEM. NIGH
LOWS WILL BE COOL FOR SURE...BUT CLOUD COVER WILL BE THE DETERMINING
FACTOR ON HOW COOL. TEMPERATURE RECOVERY BEGINS SUNDAY AS THE HIGH
SHIFTS EAST AND WE GET RETURN FLOW. THE NEXT FRONTAL SYSTEM WILL BE
ACROSS THE NORTHERN AND CENTRAL LAKES COME SUNDAY.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
THE WARM FRONT WILL BE SLOWLY MOVING NORTHEAST ACROSS THE
FORECAST AREA THIS AFTERNOON AND THE FIRST PART OF TONIGHT. CANNOT
RULE OUT A FEW NEW SHOWERS POPPING UP BUT MOST AREAS WILL LIKELY
SEE SCATTERED CUMULUS AND PATCHES OF MID AND HIGH CLOUDS AND
REMAIN VFR. THE SOUTH TO SOUTHWEST WIND WILL PICK UP...ESPECIALLY
TUESDAY MORNING. WE SHOULD BE CAPPED ON TUESDAY AS THE RIDGE ALOFT
BUILDS OVER THE AREA SO IT WILL LIKELY BE VFR/CLEAR.
OUTLOOK...NON VFR WITH POSSIBLE SHOWERS/THUNDERSTORMS WEDNESDAY
THROUGH THURSDAY. WILL LIKELY HAVE SOME NON VFR CEILINGS ACROSS
NE OH/NW PA THURSDAY AND FRIDAY.
&&
.MARINE...
SOUTHERLY FLOW TODAY AND A RELATIVELY NICE DAY ON THE LAKE. THERE
MAY BE A SHOWER OR THUNDERSTORM TODAY AS A WARM FRONT PUSHES
NORTHEAST ACROSS THE LAKE. FLOW COMES AROUND TO THE SOUTHWEST
TUESDAY AND PICKS UP ENOUGH THAT A SMALL CRAFT ADVISORY MAY BE
NEEDED ALONG THE EAST HALF/END. WINDS BEGIN TO DECREASE TUESDAY
NIGHT INTO WEDNESDAY AS A WEAKENING COLD FRONT BEGINS TO SINK SOUTH
ACROSS THE CENTRAL LAKES. WINDS SHIFT TO THE NORTHWEST BY THURSDAY
MORNING. SOME OF THE BETTER COLD AIR ADVECTION IS DELAYED UNTIL
FRIDAY. AT THAT POINT WINDS WILL PICK UP AND SMALL CRAFT CONDITIONS
WILL BE LIKELY. A MUCH COOLER AIR MASS WILL BRING LAKE EFFECT RAIN
SHOWERS TOO.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...DJB/KUBINA
SHORT TERM...KUBINA
LONG TERM...OUDEMAN
AVIATION...KOSARIK
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
559 PM EDT MON SEP 9 2013
.SYNOPSIS...
A WARM FRONT DRAPED ACROSS WESTERN PENNSYLVANIA THIS EVENING WILL
PUSH THROUGH THE ENTIRE REGION EARLY TUESDAY MORNING. UNSEASONABLY
HOT AND HUMID CONDITIONS ARE EXPECTED THROUGH MIDWEEK WITH
SCATTERED SHOWERS AND THUNDERSTORMS. A SIGNIFICANT COOLING TREND
IS EXPECTED BEHIND A COLD FRONT WITH BELOW NORMAL TEMPERATURES
FRIDAY INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
SFC ANALYSIS PLACES WARM FRONT ACROSS WESTERN PA EARLY THIS
EVENING. HEATING OF WARM/HUMID AIR MASS WEST OF FRONT HAS RESULTED
IN CAPES NR 2000 J/KG /21Z SPC MESOANALYSIS/ AND SCT TSRA IN THE
VICINITY OF PITTSBURGH. JUST TO THE NE...EDGE OF THE WARM
ADVECTION IS PRODUCING ABUNDANT CLOUD COVER AND A FEW SHRA RUNNING
FROM NR ERIE INTO CENTRAL PA.
ANY TSRA WILL VERY LIKELY DIE...AS THEY DRIFT TOWARD MORE STABLE
AIR MASS ACROSS THE LAUREL HIGHLANDS THIS EVENING. HOWEVER...HAVE
RAISED POPS CONSIDERABLY ACROSS THE NW MTNS BASED ON LATEST RADAR
TRENDS. THE ENTIRE REGION STANDS THE CHC OF SEEING A SHOWER
OVERNIGHT AS WARM FRONT PUSHES INTO THE AREA. HOWEVER...WITH
EXCEPTION OF EARLY SHOWERS OVR THE NW MTNS...WILL KEEP POPS ON THE
LOW SIDE BASED ON OPER AND ENSEMBLE QPF.
ANOTHER ISSUE CONCERNS THE POTENTIAL OF FOG LATE TONIGHT. AREA
MOST LIKELY TO SEE SIG VSBY REDUCTIONS WILL BE JUST NORTH OF THE
WARM FRONT ACROSS NE PA. LATEST SREF AND RAP SUPPORT THIS SCENARIO
WITH THE NE COUNTIES SEEING THE HIGHEST PROBS OF LOW VSBY AND
HIGHEST SFC RH/S RESPECTIVELY.
CLOUD COVER AND INCREASING HUMIDITY WILL LEAD TO A MUCH MILDER
NIGHT WITH LOWS RANGING FROM THE U50S ACROSS THE NE COUNTIES...TO
BTWN 60-65F ELSEWHERE.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
TUESDAY LOOKS LIKE AN ALMOST TYPICAL MID SUMMER DAY WITH HIGHS
WELL UP INTO THE 80S IN MOST PLACES...ALONG WITH HUMIDITY
BORDERING ON OPPRESSIVE. AN ISOLATED SHOWER OR STORM CANNOT BE
RULED OUT BUT WITH MODEL FCST TEMPS IN THE MID LEVELS TOPPING
10C...THE CAP WILL BE PRETTY HARD TO BREAK. I PLAN ON DOWNPLAYING
THE ALREADY LOW POPS WE HAVE IN THE FCST.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
PARTLY TO MOSTLY CLOUDY SKIES TUESDAY NIGHT WITHIN THE EXTENSIVE
WARM SECTOR...WILL COMBINE WITH A SOUTHERLY LIGHT WIND AND SFC
DEWPOINTS IN THE MID TO UPPER 60S...LEADING TO A MUGGY NIGHT WITH
JUST A SCHC FOR TSRA PERSISTING ACROSS NRN PENN.
LIKELY THE HOTTEST DAY UNTIL LATER NEXT SPRING OR SUMMER WILL OCCUR
WEDNESDAY...WITH HIGH TEMPS REACHING INTO THE MID 80S /MTNS/ AND
LOWER 90S ACROSS THE LOWER SUSQ VALLEY.
A PRE-FRONTAL/LEE TROF WILL LIKELY DEVELOP ACROSS THE SUSQ VALLEY
WEDNESDAY...HELPING TO FOCUS THE BEST CHC FOR AT LEAST SCATTERED
AFTERNOON TSRA THERE. ACROSS THE NW...THE FIRST OF TWO SFC CFRONTS
WILL APPROACH LATER IN THE DAY/EVENING...SPARKING A BKN BAND OF
SHOWERS AND SCATTERED TSRA.
THE PAIR OF COLD FRONTS WILL MOVES SE ACROSS THE STATE WED NIGHT AND
THURSDAY...WITH ANOTHER ROUND OR TO OF SHOWERS/TSRA. FOR LATE IN THE
WEEK AND OVER THE UPCOMING WEEKEND...A SPRAWLING/COOL CANADIAN HIGH
AND ANOMALOUSLY DEEP UPPER TROUGH WILL MOVE SOUTHEAST FROM THE
GLAKES...BRINGING A RETURN TO MUCH LOWER DEWPOINTS AND BELOW NORMAL
TEMPS.
THE ZERO C 850 MB ISOTHERM /IN THE LATEST...03Z SREF/ WILL MOVE OVER
THE NRN GREAT LAKES REGION THURSDAY...BEFORE DIVING SOUTHEAST TO
MAKE A RARE EARLY SEASON APPEARANCE NEAR THE PENN/NEW YORK BORDER
AND SOUTHERN NEW ENGLAND COAST FRIDAY INTO EARLY SATURDAY. THESE -2
TO -3 SIGMA TEMPS AT 850 MB WILL UNDOUBTEDLY LEAD TO WIDESPREAD COLD
AIR STRATO CU WITH LAKE EFFECT AND OROGRAPHICALLY ENHANCED SHOWERS.
WE MAY BE UNDERPLAYING THE AMOUNT OF CLOUDS AND POPS FOR FRIDAY AND
SATURDAY HERE IN CENTRAL AND NRN PENN WITHIN THE COLD...GUSTY AND
WELL-ALIGNED DEEP NWRLY FLOW.
SO...IN SUMMARY...THE MAIN STORIES FOR THIS PERIOD WILL BE THE HEAT
TO START...SCATTERED STRONG TO SEVERE STORMS POSSIBLE LATER TUESDAY
AND WEDNESDAY...MAINLY NORTH OF THE REGION/...AND THE UNSEASONABLY
CHILLY AIRMASS TO CLOSE IT OUT.
&&
.AVIATION /22Z MONDAY THROUGH SATURDAY/...
VIZ LOOP SHOWS LOW CLOUDS BUILDING IN THE WEAK UPSLOPE FLOW OVER
SOUTH CENTRAL PA. THE AOO CIG HAS ACTUALLY BEEN LOWERING DESPITE
WHAT LOOKS LIKE SOME MIXING STARTING TO DEVELOP IN THE LOW CLOUD
SHIELD. WOULD NOT BE SURPRISED TO EVEN SEE THE CEILING AT UNV GO
BRIEFLY MVFR BEFORE THE CLOUDS MIC AND BASES LIFT UP THIS
AFTERNOON.
THE LARGER PICTURE SHOWS AN INCREASINGLY MOIST SOUTHERLY FLOW
BEGINNING TO DEVELOP WHICH WILL BRING A CHANCE OF A SHOWER OR
THUNDERSTORM LATER TODAY INTO TONIGHT...MAINLY OVER WESTERN
AREAS.
MVFR/IFR CIGS ARE LIKELY ACROSS THE SERN TERMINALS LATE
TONIGHT. LOW CIGS WILL IMPROVE EARLY TUES GIVING WAY TO VFR BY
TUES AFTERNOON.
OUTLOOK...
TUE...AM LOW CLOUDS SOUTH/EAST.
WED...SCT PM TSTM IMPACTS PSBL.
THU...SCT-NMRS TSTM IMPACTS PSBL WITH COLD FROPA.
FRI...MVFR/SCT SHOWERS PSBL N/W...VFR CENTRAL/EAST.
SAT...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD/LA CORTE
SHORT TERM...LA CORTE
LONG TERM...GARTNER/MARTIN
AVIATION...LA CORTE
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1236 PM CDT MON SEP 9 2013
.UPDATE...FOR 18Z AVIATION DISCUSSION.
&&
.AVIATION...18Z AVIATION DISCUSSION.
UNCERTAINTIES...MVFR TO IFR FOG DEVELOPMENT CKV AND CSV. ISO MAINLY DIURNAL
DRIVEN SHWRS/TSTMS ARE POSSIBLE THRU 10/02Z...BUT WITH LOCATION DEVELOPMENT
SO UNCERTAIN...WILL NOT MENTION IN TAFS. EXPECT SCT CU TO SCT/BKN CI THRU
10/02Z THOUGH. SCT/BKN CI WILL CONTINUE THRU 10/15Z...BUT PER USUAL LOW
LEVEL MOISTURE POOLING POTENTIAL...MVFR FOG STILL POSSIBLE CKV AND CSV...
WITH TYPICAL TEMPO IFR POSSIBLE CSV...PER MAX RADITIONAL COOLING POTENTIAL
AND LIGHT WINDS. WITH UPPER LEVEL RIDGING INFLUENCES...EXPECT ONLY SCT CU
TO SCT/BKN CI FROM 10/15Z-10/18Z.
&&
.PREV DISCUSSION... /ISSUED 607 AM CDT MON SEP 9 2013/
AVIATION UPDATE...FOR 12Z TAF PACKAGE...
SHORTWAVE IS PRODUCING WEAK STORMS IN VICINITY OF KCKV AND KBNA
THIS MORNING AT TAF ISSUANCE. RADAR TRENDS SHOW MOSTLY JUST RAIN.
MAY SEE SOME FURTHER DEVELOPMENT THIS MORNING AS AREA OF LIFT GETS
CLOSER BUT MODELS DO NOT HAVE THIS FEATURE REACHING FAR ENOUGH
SOUTHEAST TO IMPACT KBNA SO LEFT TEMPO GROUP AND STUCK WITH JUST
VCSH. OTHERWISE...VFR EXPECTED.
PREV DISCUSSION... /ISSUED 257 AM CDT MON SEP 9 2013/
DISCUSSION...
WEAK VERY SUBTLE SURFACE BOUNDARY EXTENDS FROM SAINT LOUIS DOWN
THROUGH FAR WESTERN KENTUCKY INTO SOUTHERN MIDDLE TENNESSEE. WEAK
SHORT WAVE AT THE MID LEVELS OVER FAR WESTERN KENTUCKY CAN BE SEEN
IN 00Z EURO AT 06Z AND TO SOME EXTENT IN THE LASTEST RUC LOOP OF 700
MBAR COLD TEMP AXIS. AGAIN VERY SUBTLE FEATURES. ISOLATED CONVECTION
DEVELOPED JUST AFTER MIDNIGHT IN FAR NORTHWEST MIDDLE TENNESSEE
AND HAS MOVED LITTLE LAST COUPLE OF HOURS. 500 MBAR HIGH TO OUR
WEST WILL WORK EASTWARD TODAY KEEPING SUBSIDENCE ACROSS THE AREA
AND WITH LITTLE IN THE WAY OF FORCING SO AM EXPECTING TO SEE ONLY
ISOLATED CONVECTION ONCE AGAIN. THINK AREAS WEST OF INTERSTATE 65
MIGHT BE FAVORED BUT AGAIN LOW POPS. SURFACE BOUNDARY WILL LIFT
NORTH TODAY WHILE SHORT WAVE DAMPS OUT. THIS WILL PLACE MID STATE
PRETTY MUCH IN THE GRIPS OF UPPER LEVEL RIDGING WITH LOW POP
CHANCES FOR CONVECTION BOTH DURING THE DAY AND NOCTURNALLY AT
LEAST THROUGH WEDNESDAY. BY THURSDAY A SURFACE FRONT WILL BE
MAKING ITS WAY SOUTHWARD FROM GREAT LAKES REGION AND THIS WILL
INCREASE POPS FOR THURSDAY AND THURSDAY NIGHT. WITH ALL THE
RIDGING IN PLACE OF RECENT DAYS AND CONTINUED OFF CONTINENT WIND
FLOW I JUST DONT SEE MUCH IN THE WAY OF MOISTURE TO FEED THIS
SOUTH BOUND SYSTEM SO AM EXPECTING RAINFALL AMOUNTS TO LIKELY BE
LOW. FRONT GETS SOUTH OF MID STATE ON FRIDAY WITH 1024 SURFACE
HIGH CENTERED OVER LAKE SUPERIOR. COOLER AND MORE SEASONABLE TEMPS
WILL FOLLOW FRONTAL PASSAGE. SURFACE HIGH WILL RIDGE DOWN ACROSS
THE MID STATE THROUGH THE WEEKEND.
AS FOR TEMPS...MET IS RUNNING 2 TO 4 DEGREES COOLER THAN MAV FOR
DAYTIME HIGHS THROUGH WEDNESDAY AND KEEPS TRYING TO GO TOWARD
CLIMATOLOGY WHILE MAV IS WANTING TO KEEP THINGS MORE HEATED. I
BASICALLY KNOCKED ONE TO TWO DEGREES OFF THE MAV FOR DAYTIME HIGHS
THROUGH WEDNESDAY OR CLOSER TO AVERAGE OF THE TWO MODELS. BOTH MET
AND MAV ARE CLOSE ON NIGHTTIME LOWS THROUGH WEDNESDAY SO I FOLLOWED.
FOLLOWING FRONTAL PASSAGE EXPECT HIGHS ON FRIDAY TO BE A GOOD 10
DEGREES COOLER THAN WHAT WE HAVE BEEN SEEING. TEMPS FRIDAY THROUGH
THE WEEKEND WILL BE IN THE LOW TO MID 80S WITH MID AND UPPER 70S
ALONG THE UPPER CUMBERLAND.
BOYD
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
137 PM EDT MON SEP 9 2013
.SYNOPSIS...
A WEAK COOL FRONT WILL DRIFT SOUTH INTO THE CAROLINAS TODAY AND
GRADUALLY DISSIPATE THIS EVENING. HIGH PRESSURE BUILDING NORTH OF
THE AREA WILL WEDGE SOUTH ALONG THE APPALACHIANS THIS MORNING
BEFORE SLIDING QUICKLY EAST AND OFFSHORE THE MID ATLANTIC COAST
THIS AFTERNOON. HIGH PRESSURE ALOFT SLIDES EAST INTO THE AREA BY
TUESDAY BRINGING A RETURN TO MORE SUMMERLIKE WEATHER FOR MID WEEK
AHEAD OF A STRONG COLD FRONT THAT ARRIVES ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1140 AM EDT MONDAY... INCREASED CLOUD COVER FOR THIS
AFTERNOON AND LOWERED TEMPERATURES. CLOUDS AND LOW LEVEL COOL POOL
ARE BANKING UP AGAINST THE BLUE RIDGE RIDGE WITH CU FIELD
DEVELOPING ALONG SOUTHERN PORTIONS OF CWA WHERE THERE WAS SOME
MORNING SUNSHINE. SHAPED THE AFTERNOON POPS TOWARDS THE HRRR WITH
CONVECTION ACROSS HIGHER TERRAIN AND SPOTTY ACTIVITY IN THE EAST.
MORE ADJUSTMENTS THIS AFTERNOON...
AS OF 910 AM EDT MONDAY...
WITH THIS MORNING RNK 12Z/8AM SOUNDING SHOWING SHALLOW MOISTURE
UP TO 870 MB...EXPECT CLOUD COVER TO PERSIST FOR A COUPLE OF HOURS
THIS MORNING WITH THE WEAK FRONT AND LOW LEVEL WEDGE. WITH THIS
RICH CLOUD COVER...LOWERED TEMPERATURES FOR THIS MORNING INTO
THIS AFTERNOON. ISOLATED TO SCATTERED POPS SUPPORTED BY
ECMWF...GFS NAM...MAINLY ACROSS THE HIGHER TERRAIN. 06Z RNK WRF
ARW PLACED THE FOCUS OF CONVECTION ACROSS THE NORTHWEST
MOUNTAINS. WILL SHAPE POPS AND ISC GRIDS AS MORNING PROGESSES.
AS OF 230 AM EDT MONDAY...
FORECAST REMAINS RATHER UNCERTAIN OVER THE NEXT 24 HOURS WITH
A WEAK FRONT DROPPING TO THE SOUTH THIS MORNING AND A LOW LEVEL
WEDGE DEVELOPING BEHIND THE BOUNDARY ALONG THE MOUNTAINS INTO
THIS AFTERNOON. KEY IS WHETHER OR NOT ANY LOW CLOUDS DEVELOP
WITHIN THE LOW LEVEL COOL POOL THIS MORNING AND BANK UP ALONG THE
BLUE RIDGE LONGER THAN EXPECTED DESPITE HIGH PRES EXITING OFF TO
THE NE AFTER MIDDAY. MODELS CONTINUE TO SUGGEST THIS SCENARIO WITH
ONGOING ISOLATED -SHRA FADING OUT EAST BY DAYBREAK ONLY TO HAVE
LOW CLOUDS SPILL BACK WEST AIDED BY WEAK UPSLOPE. THEREFORE HAVE
TRENDED CLOUDIER EARLY ON EASTERN HALF WITH LESS CLOUDS WEST
WHERE EARLY FOG/STRATUS MORE PREVALENT.
LOW LEVEL FLOW WILL GRADUALLY VEER AROUND TO THE SOUTH/SW FROM
WEST TO EAST THIS AFTERNOON AS THE HIGH EXITS WITH INCREASING
WEAK MOISTURE CONVERGENCE FAR WEST. HOWEVER MAY STILL SEE A WEAK
RESIDUAL WEDGE HANG IN OUT EAST PER SUBTLE SE FLOW AND LINGERING
STABILITY OFF GUIDANCE. THIS SHOULD KEEP ANY ADDED SHRA CONFINED
TO THE MOUNTAINS WHERE MODELS DEPICT BEST AXIS OF THETA-E AND
DECENT CAPES AHEAD OF PERHAPS A WEAK MID LEVEL WAVE SPILLING IN
FROM THE NW LATE. THIS COULD BE ENOUGH TO SPARK MAINLY ISOLATED
SHRA/TSRA BUT IFFY GIVEN LACK OF MUCH LOW LEVEL FOCUS...BUILDING
5H HEIGHTS FROM THE WEST AND ONLY SHALLOW MOISTURE. THUS STAYING
WITH 20/30 POPS WEST WHICH MESHES BEST WITH THE LATEST ENSEMBLES
AND DRY EAST WHERE CLOUDS MAY LINGER. HIGH TEMPS TRICKY PENDING
TIMING OF MORE INSOLATION EAST AND WEAK VEERING FLOW FOLLOWING A
WARM START. IF CLOUDS LOCK IN ACROSS THE NE THEN MAY BE TOUGH TO
REACH 80...WHILE ELSW COULD ZOOM UP ESPCLY WEST GIVEN WEAK
DOWNSLOPING SO BUMPED UP HIGHS THERE AND TRIMMED BACK OUT EAST.
UPPER RIDGE OVER THE MIDWEST SHIFTS EAST OVERNIGHT AS THE SURFACE
HIGH EXITS FARTHER EAST WHILE ELONGATING BACK INLAND TO OVER THE
CAROLINAS LATE. THIS SHOULD ALLOW FOR A WEAK SUBSIDENCE REGIME TO
LINGER WITH ANY RESIDUAL EVENING SHRA FROM EARLIER OUTFLOW...AND
POSSIBLY ISOLATED SHRA ACROSS THE FAR NW WITH ANY FAINT IMPULSE
SPILLING SE OVERNIGHT. OTRW PC NORTH/WEST TO CLEAR ELSW WITH
THINGS A BIT MORE MUGGY GIVEN LOWS MAINLY IN THE 60S.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM EDT MONDAY...
UPPER RIDGE CONTINUES TO BUILD OVER THE REGION ON TUESDAY WITH
AN BERMUDA HIGH PATTERN MAINTAINING ITSELF THROUGH WEDNESDAY. FOR
THE REGION THIS WILL MEAN A RETURN OF LOW LEVEL MOISTURE INTO THE
REGION AND DIURNAL SHOWERS AND STORMS DEVELOPING...ESPECIALLY OVER
THE MOUNTAINS. TEMPERATURES WILL ALSO TREND WARMER. DAYTIME HIGHS
IN THE UPPER 80S TO AROUND 90 WILL BE COMMON ACROSS THE PIEDMONT
WITH A MIX OF UPPER 70S TO MID 80S IN THE MOUNTAINS. OVERNIGHT
LOWS WILL BE IN THE LOW TO MID 60S.
THE UPPER RIDGE BEGINS TO BECOME DISPLACED WESTWARD IN RESPONSE A
DEEPENING TROUGH ACROSS THE GREAT LAKES REGION BY WEDNESDAY NIGHT.
THIS TROUGH IS PROGGED TO DEEPEN ACROSS THE EAST COAST BY THURSDAY
AND BRING AN ASSOCIATED COLD FRONT THROUGH THE REGION BY THURSDAY
EVENING. THE RESULT WILL BE A MORE ORGANIZED SERIES OF SHOWERS
AND STORMS DEVELOPING BOTH OVER THE AREA...AND ALSO MOVING INTO
THE REGION IN ASSOCIATION WITH THE FRONT. TEMPERATURES WILL ONLY
BE SLIGHTLY COOLER DURING THE DAY THURSDAY COMPARED TO THE
PREVIOUS TWO DAYS THANKS MAINLY TO MORE CLOUDS AND MORE
PRECIPITATION. LOWER DEW POINT AIR MOVES INTO THE AREA BEHIND THE
FRONT THURSDAY NIGHT...AND THUS ALLOW FOR COOLER LOW TEMPERATURES.
MID TO UPPER 50S ARE EXPECTED ACROSS THE MOUNTAINS WITH LOWER 60S
ACROSS THE PIEDMONT.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 1230 PM EDT SUNDAY...
UPPER RIDGE RETROGRADES BACK TO THE CENTRAL PLAINS BY FRIDAY WITH A
500 MB TROF DIGGING IN THE EASTERN UNITED STATES. ECMWF CLOSES OFF
AN UPPER LOW OVER NEW ENGLAND ON SATURDAY WHILE THE GFS IS FASTER
MOVING THE LONG WAVE TROF OFFSHORE. EITHER WAY...NET RESULT WILL
STILL BE NORTHWEST FLOW FOR THE FORECAST AREA.
BOTH THE ECMWF AND GFS ENSEMBLES HAVE SIMILAR TIMING WITH A SURFACE
COLD FRONT CROSSES THROUGH THE COUNTY WARNING AREA ON THURSDAY.
SOUTHWEST WINDS ON THURSDAY WILL KEEP TEMPERATURES ABOVE NORMAL AND
WILL BRING DEEP MOISTURE INTO THE AREA AHEAD OF THE FRONT. A LARGE
HIGH PRESSURE SYSTEM...ALONG WITH A COOLER AND DRIER AIRMASS BUILDS
IN BY SATURDAY. APPEARS THAT 850MB TEMPERATURES WILL LOWER IN THE +8
TO +10 RANGE BEHIND THE FRONT.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 134 PM EDT MONDAY...
SCT TO BKN MVFR CLOUDS WITH ISOLATED IFR ACROSS THE SOUTHERN BLUE
RIDGE MOUNTAINS THIS AFTERNOON INTO TONIGHT. HIGH PRESSURE WILL
SHIFT EAST AND OFF THE MID ATLANTIC COAST THIS AFTERNOON INTO
TONIGHT. THIS SHOULD ALLOW LOW LEVEL WINDS TO VEER AROUND TO THE
SOUTH/SW AND HELP SCOUR OUT ANY RESIDUAL LOW CLOUDS THAT MAY BE
STUCK OUT EAST. SCT-BKN 4-6KFT CU FIELD EXPECTED IN THE WEST THIS
AFTERNOON INTO TONIGHT. ISOLATED CELLS FORMING ON KFCX WSR-88D AT
17Z IN THE UNSTABLE AIR ACROSS WESTERN MOUNTAINS.
THIS ISOLATED CONVECTION THIS AFTERNOON WILL DIMINISH WITH THE
LOSS OF SOLAR HEATING THIS EVENING. ANY SHOWER OR THUNDERSTORM
LOOKS TOO ISOLATED TO MENTION IN THE TAF SITES. LOW LEVEL
MOISTURE AND LIGHT WINDS TONIGHT WILL RESULT IN AREAS OF FOG
OVERNIGHT. LWB HAS THE BEST CHANCE FOR FOG TONIGHT...WITH LIFR
EXPECTED OVERNIGHT INTO TUESDAY MORNING.
TUESDAY INTO MID WEEK...EXPECT A RETURN TO MORE TYPICAL SUMMERLIKE
WEATHER WITH INCREASING CHANCES FOR DIURNALLY-DRIVEN SHOWERS AND
THUNDERSTORMS. AT THIS POINT...NO WIDESPREAD EXTENDED DURATION OF
POOR AVIATION CONDITIONS ARE EXPECTED THROUGH MID WEEK...OUTSIDE OF
EARLY MORNING FOG AND PATCHY LOW STRATUS. ANOTHER COLD FRONT WILL
ARRIVE ON THURSDAY WITH PERHAPS A MORE SUBSTANTIAL BAND OF SHOWERS
AND STORMS THURSDAY AFTERNOON...WHICH MAY ALLOW FOR A PERIOD OF SUB-
VFR CONDITIONS INTO THURSDAY EVENING. MUCH DRIER AND COOLER AIR
LOOKS TO ARRIVE BEHIND THE FRONT MARKING FOR THE RETURN OF
WIDESPREAD VFR FOR THE END OF THE WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/KK
SHORT TERM...DS
LONG TERM...AMS
AVIATION...JH/KK
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 403 PM CDT MON SEP 9 2013
PLENTY OF QUESTIONS REMAIN REGARDING THE CHANCE FOR CONVECTION
TODAY. THERE WERE EVEN A FEW SHOWERS THAT WERE ON THEIR WAY OUT
OF THE AREA AT 20Z THAT APPEAR TO HAVE DEVELOPED ALONG A BOUNDARY
FROM THE THUNDERSTORM COMPLEX THAT MOVED ACROSS MINNESOTA
OVERNIGHT. THERE IS PLENTY OF INSTABILITY...MESOANALYSIS HAD
MUCAPES MAINLY IN THE 1000-3000J/KG RANGE EXCEPT NEAR THE UPPER
MICHIGAN BORDER WHERE THEY WERE IN THE 500-1000J/KG RANGE AT 20Z.
WEAKEST CIN WAS FROM NORTH CENTRAL AND NORTHEAST WISCONSIN
SOUTHWEST INTO EASTERN IOWA...BUT STRONG WARM ADVECTION ALOFT
CONTINUED TO HAMPER CONVECTIVE DEVELOPMENT ACROSS THE AREA.
LIGHT EAST OR SOUTH WINDS THIS MORNING HAVE BECOME SOUTHERLY AND
INCREASED DURING THE DAY. A WARM FRONT WAS MOVING NORTHEAST INTO
CENTRAL WISCONSIN THIS AFTERNOON AND WAS FORECAST TO MAKE IT TO
NEAR THE WISCONSIN/UPPER MICHIGAN BORDER BY 00Z. THIS MAY BE A
BIT TOO QUICK BASED ON ITS SPEED DURING THE DAY. THE WESTERLY FLOW
OF WARM AIR ALOFT WAS HELPING TO PRODUCE STRONG LOW-LEVEL AND
DEEP-LAYER SHEAR...ESPECIALLY ACROSS NORTHERN WISCONSIN AND UPPER
MICHIGAN.
STORMS MAY FIRE AS THE SURFACE LOW IN EASTERN MINNESOTA MOVES
ACROSS NORTHERN WISCONSIN LATER TONIGHT. EXPERIMENTAL COMPOSITE
REFLECTIVITY FROM THE 18Z HRRR DID NOT REALLY SHOW ANYTHING ACROSS
THE AREA...THOUGH IT DID SUGGEST CONVECTIVE ACTIVITY IN
CENTRAL/SOUTHERN WISCONSIN TODAY THAT DID NOT DEVELOP. IF STORMS
DO DEVELOP...THEY COULD PRODUCE LARGE HAIL AND DAMAGING WINDS. AN
ISOLATED TORNADO WAS EVEN MENTIONED BY SPC IN THEIR DAY ONE
OUTLOOK...WITH STORMS DEVELOPING INTO A FORWARD PROPAGATING MCS
WITH LLJ DEVELOPMENT...RESULTING IN MAINLY A DAMAGING WIND EVENT
THEREAFTER.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 403 PM CDT MON SEP 9 2013
LITTLE CHANGE IN SCENARIO FROM PAST FEW DAYS WITH AREA
TRANSITIONING INTO A NORTHWEST FLOW REGIME BY WED. MODELS IN
SIMILAR AGREEMENT THROUGH THE END OF THE WORK WEEK...THEN BEGIN
TO DIFFER AS MORE ZONAL PATTERN BUILDS IN. PRECIPITATION CHANCES
FIRST PART OF FORECAST MAIN CONCERNS.
WEAK COLD FRONT WILL SLOWLY SAG SOUTH THROUGH CWA ON TUE...THEN
SOUTH OF THE REGION TUESDAY NIGHT. MODELS TRENDING DRY THROUGH AM
WITH LIMITED CONVERGENCE ALONG FRONT AND NO UPPER SUPPORT. MODELS
A BIT MORE BULLISH ON QPF CHANCES LATE TUE AFTN AND OVERNIGHT...AS
WEAK WAVE MOVES NORTHEAST ALONG FRONT IN RESPONSE TO SHORT WAVE
TROF AND SOME JET ENERGY MOVING THROUGH. BUMPED POPS UP TO LIKELY
IN THE FAR SOUTH. PW`S STILL IN THE 1.5 TO 2 INCH RANGE WITH HEAVY
RAIN BIGGEST THREAT.
POSSIBILITY OF SHOWERS CONTINUES INTO THU AS UPPER DISTURBANCES
DROP SOUTHEAST THROUGH THE WESTERN LAKES. LINGERING LOW LEVEL
MOISTURE TO LEAD TO BETTER INSTABILITY AND CHANCE OF PCPN ON WED BUT
LATEST RUNS SHOW RATHER STRONG SYSTEM DROPPING THROUGH ON THU.
HAVE STAYED DRY THU ATTM GIVEN MOISTURE AND TIMING CONCERNS.
HIGH PRESSURE BUILDS IN LATER THU FOR DRY CONDITIONS THROUGH SAT.
HIGH TO SHIFT EAST OF AREA SAT NIGHT ALLOWING RETURN FLOW TO
DEVELOP. THIS WILL BRING A GOOD CHANCE OF SHOWERS AND ISOLD TSTMS
TO THE REGION SAT NIGHT INTO SUN.
COLDER AIR MOVES IN BEHIND STRONG COLD FRONT ON WED WITH
TEMPERATURES FALLING BACK TO NORMAL OR BELOW FOR REMAINDER OF
PERIOD. COOLEST TEMPERATURES EXPECTED FRI WITH COOL NORTHEAST
FLOW.
MAINTAINED SMALL CHANCE FOR LAKE EFFECT SHOWERS ON THU...THOUGH
WINDS MARGINAL. WILL LIKELY SEE LAKE CLOUDS AT TIMES OVER THE
NORTH THOUGH CAUSING HAVOC WITH LOW TEMP FORECASTS.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 111 PM CDT MON SEP 9 2013
IFR CIGS AND VSBYS ACROSS MUCH OF THE FORECAST AREA
WERE THE FIRST AREA OF CONCERN. VISIBLE SATELLITE IMAGERY SHOWED
STRATUS AND FOG ACROSS SOUTHERN AND CENTRAL WISCONSIN RAPIDLY
ERODING FROM THE SOUTH DURING THE LATE MORNING HOURS AS A WARM
FRONT PUSHED NORTHWARD. THE FRONT WILL CONTINUE TO MAKE PROGRESS
TO THE NORTH BUT NORTHERN WISCONSIN SHOULD BE SLOWER TO CLEAR
DUE TO REMNANTS OF OVERNIGHT/MORNING CONVECTION AND SOME MID/HIGH
CLOUDS OVER THAT PART OF THE STATE. WOULD EXPECT VFR CONDITIONS TO
PREVAIL ACROSS THE VAST MAJORITY OF THE AREA BY LATE AFTERNOON.
SURFACE WINDS WILL SHIFT TO THE SOUTH AND INCREASE...THEN BECOME
SOUTHWEST AS WINDS ALOFT VEER AND INCREASE CONSIDERABLY. HAVE LEFT
THE MENTION OF LLWS IN TAFS AS THE LLJ INCREASES TO AROUND 50 KNOTS
LATE TONIGHT.
CONVECTION BECOMES A CONCERN FOR THE EVENING AND LATE NIGHT IN THE
NORTH DUE TO ABUNDANT SBCAPE...MAINLY 2000-3000J/KG...AND PLENTY
OF LOW-LEVEL AND DEEP-LAYER WIND SHEAR. THE PRESENCE OF 150-300J/KG
OF CIN MAKES DEVELOPMENT LESS LIKELY...BUT THE CAP MAY END UP
GETTING BROKEN BY THE SURFACE BOUNDARY. HAVE ONLY USED A PROB30 AT
RHI TO COVER THIS POSSIBILITY. IF STORMS DO DEVELOP...THERE IS A
PRETTY GOOD CHANCE THAT SEVERE WEATHER WILL OCCUR.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MG
LONG TERM......TE
AVIATION.......MG