Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/26/13
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
310 PM MST SAT AUG 24 2013
.SYNOPSIS...
A STORMY PERIOD IS ANTICIPATED THIS WEEKEND ACROSS THE REGION WITH
BELOW NORMAL TEMPERATURES. HEAVY RAIN AND LOCALIZED FLOODING MAY
OCCUR...ESPECIALLY ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA. PRECIPITATION CHANCES DECREASE BY EARLY NEXT WEEK...AND
INCREASED MOISTURE WILL CONTINUE THROUGH THE REMAINDER OF THE
WEEK...ALONG WITH NEAR NORMAL TEMPERATURES.
&&
.DISCUSSION...
WET AND UNSETTLED WEATHER SCENARIO DEVELOPING THIS AFTERNOON PRETTY
MUCH AS EXPECTED...AS MOISTURE FROM TROPICAL SYSTEM IVO CONTINUES TO
SHED TO THE NORTH AND INTO ARIZONA AND SE CALIFORNIA. BEST
MLCAPE/SURFACE BASED CAPE VALUES ARE LOCATED ACROSS SERN CA AND SWRN
AZ. PWAT VALUES ARE UP...WITH PHOENIX REPORTING 1.6 INCHES ON THE
MORNING RAOB. SURFACE DEWPOINTS AT 2 PM RANGED FROM THE MID 5OS TO
MID 60S OVER THE CENTRAL AZ DESERTS...TO THE MID 60S TO LOW 70S OVER
PORTIONS OF IMPERIAL COUNTY. STRONG THUNDERSTORMS HAVE BEEN
DEVELOPING THIS AFTERNOON WEST OF THE LOWER CO RIVER VALLEY WHERE
INSTABILITY IS GREATEST...AND THEY HAVE PRODUCED VERY HEAVY
RAINFALL. RADAR INDICATED OVER 4 INCHES OF RAIN FELL WEST OF THE
SALTON SEA DURING THE EARLY AFTERNOON. STRONG CONVECTION CAN BE
EXPECTED FOR THE REST OF THE AFTERNOON AND INTO THE EVENING HOURS
OVER OUR WESTERN DESERTS.
MLCAPE VALUES ARE MUCH LOWER OVER SOUTH CENTRAL AZ...MOSTLY LESS
THAN 600 J/KG...SO LESS CONVECTION IS EXPECTED. HOWEVER THERE HAS
BEEN QUITE A BIT OF SUNSHINE SOUTH AND EAST OF PHOENIX THIS MORNING
AND EARLY AFTERNOON AND STORMS WILL LIKELY START TO GENERATE AND
MOVE NORTH INTO OUR AREA LATER THIS AFTERNOON AND INTO THE EVENING
HOURS. THUS...WE WILL STILL CALL FOR NEARLY 50 PERCENT CHANCE OF
THUNDERSTORMS TONIGHT OVER OUR EASTERN ZONES. OTHERWISE...FORECASTS
APPEAR ON TRACK AS MOISTURE FROM DECAYING IVO WILL SPREAD INTO THE
CWA LATER TONIGHT...WITH PWAT VALUES MAXING SUNDAY INTO SUNDAY
NIGHT...IN AREAS WEST OF MARICOPA COUNTY. POPS WILL REMAIN ELEVATED
THRU SUNDAY NIGHT...MOSTLY IN THE 60 TO 80 PERCENT BALLPARK. LESS
INSTABILITY EXPECTED SUNDAY/SUNDAY NIGHT SO STORMS WILL BE LESS
SEVERE BUT THE THREAT FOR HEAVY RAIN WILL BE INCREASED DUE TO PWAT
VALUES THAT WILL CLIMB WELL ABOVE 2 INCHES. FLASH FLOOD WATCH WILL
CONTINUE FOR ALL ZONES WEST OF ZONE 23 STARTING AT 11 PM TONIGHT AND
CONTINUING THRU 11 PM SUNDAY NIGHT. LITTLE CHANGE MADE BEYOND SUNDAY
NIGHT...AS MOST OF THE EFFORTS TODAY HAVE BEEN CHASING ONGOING
FLOODING AND SEVERE WEATHER EPISODES. FOLLOWING DISCUSSION IS A MORE
DETAILED ANALYSIS FROM THE MID SHIFT.
PREVIOUS DISCUSSION...A BATCH OF SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED OVER THE METRO AREA EARLY THIS MORNING. LATEST RUC
IDENTIFIES A PERTURBATION MOVING THROUGH THE SOUTH-CENTRAL ARIZONA
DESERTS WHICH MIGHT ACCOUNT FOR THIS. THERE WAS A GRAVITY WAVE THAT
MOVED THROUGH BUT THAT WAS AT LEAST A FEW HOURS AGO. THE RUC SHOWS
THE PERTURBATION SHIFTING NORTH AFTER 12Z AND THUS STORM ACTIVITY
OVER MARICOPA COUNTY SHOULD WIND DOWN SHORTLY AFTER
SUNRISE...ALREADY QUIET ELSEWHERE IN THE FORECAST AREA. LARGER SCALE
FLOW FEATURES OF NOTE INCLUDE THE EVER-PRESENT TROUGH CENTERED NEAR
THE WEST COAST...A LARGE ANTICYCLONE/RIDGE CENTERED OVER THE
PLAINS...AN INVERTED TROUGH CENTERED NEAR THE CHIHUAHUA/TEXAS
BORDER...AND TROPICAL STORM IVO CENTERED WEST OF CABO SAN LUCAS. THE
MODELS HAVE DIFFERING SOLUTIONS ON HOW THE FLOW FEATURES MENTIONED
ABOVE WILL UNFOLD...PARTICULARLY THE INVERTED TROUGH AND THE BROADER
CYCLONIC CIRCULATION ASSOCIATED WITH IVO. FOR INSTANCE...THE GFS
CONTINUES TO TRACK THE IVO ASSOCIATED CIRCULATION TO THE NORTH
FASTER THAN ECWMF AND ESPECIALLY NAM. BY THAT SAME TOKEN...THE WAVE
ALSO DISSIPATES FASTER. THIS HAS IMPLICATIONS FOR TIMING OF
POPS/PRECIP. THERE ARE ALSO DIFFERENCES ON THE UPPER LEVEL
DIVERGENCE GENERATED BY THE APPROACHING WAVE WHICH ALSO IMPACTS
MODEL PRECIP FORECASTS. THOUGH THE NAM IS SLOWER WITH THE IVO
CIRCULATION...IT BRINGS IN A SMALLER WAVE LATER TODAY WHICH MIGHT BE
REMNANTS OF THE INVERTED TROUGH AND/OR A CONVECTIVELY GENERATED
FEATURE FROM SOUTHERN SONORA. THE NAM THUS PRODUCES A BATCH OF
DYNAMICAL FORCING SOONER THAN THE GFS AND ECWMF. THEY ALL SHOW A
MAJOR INFLUX OF MOISTURE. INTERESTINGLY...THERE ARE SOME
SIMILARITIES IN THE SPATIAL DISTRIBUTION OF THE QPF...INCLUDING
LOCAL WRF AND NMM6KM. MAINLY...FROM TONIGHT THROUGH SUNDAY NIGHT
THERE IS A HIGH QPF SWATH OVER WESTERN MARICOPA COUNTY AND SOUTHWEST
ARIZONA. AND A LESSER SWATH OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL
ARIZONA. IN BETWEEN IS A LOWER QPF SWATH...INCLUDING THE PHOENIX
METRO AREA. HOWEVER...THERE IS A GREAT DEAL OF VARIABILITY FOR
SOUTHEAST CALIFORNIA. THE GFS HAS ITS HEAVIEST SWATH...FOR OUR
FORECAST AREA...OVER EASTERN RIVERSIDE AND IMPERIAL COUNTIES. MADE
NUMEROUS ADJUSTMENTS TO THE QPF AND POP GRIDS. MODIFIED THE FLASH
FLOOD WATCH TO START IT 6 HOURS EARLIER AND TO EXTEND IT EASTWARD
OVER WESTERN MARICOPA COUNTY. IT SHOULD BE NOTED THAT WE WILL NOT
HAVE A TROPICAL STORM THAT BODILY MOVES INTO THE DESERT SOUTHWEST.
RATHER...TROPICAL MOISTURE WILL BE PUSHED NORTHWARD INTO THE REGION
AND THERE WILL BE FLOW FEATURES AIDING THE PRECIPITATION PRODUCTION.
ALSO...WHILE THE WATCH DOES NOT START UNTIL 06Z...THERE WILL LIKELY
BE SOME POTENT THUNDERSTORMS DEVELOPING WITHIN OUR AREA PRIOR TO
THAT. THE GFS...NAM...AND SREF ALL HAVE CAPE VALUES WELL IN EXCESS
OF 1000 J/KG...MAINLY OVER SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA. PRIOR TO THE ARRIVAL OF BROADER SCALE LIFT...ANTICIPATE
STORMS BEING MORE SCATTERED IN NATURE AS OPPOSED TO WIDESPREAD RAIN.
WITH HIGH CAPE VALUES...THERE WILL BE SEVERE POTENTIAL LATE THIS
AFTERNOON AND EVENING. THEREAFTER...ANTICIPATE DECREASING CAPE BUT
MORE WIDESPREAD SHOWERS WITH ISOLATED THUNDERSTORMS. WITH THE CLOUDS
AND RAIN COOLED AIR AROUND...SUNDAY TEMPS WILL BE WELL BELOW NORMAL.
EXTENDED PERIOD...UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND
CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM
COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT
FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL
TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE
GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES
NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY
PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN
PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF
THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO
NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...WINDS ARE
NOW EXPECTED TO REMAIN PRIMARY OUT OF THE EAST THROUGH THE
EVENING...AND NIGHTTIME HOURS AS OUTFLOWS FROM THUNDERSTORMS MOVE
INTO THE PHOENIX AREA. THESE THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING STRONG GUSTY WINDS AND PERIODS OF HEAVY RAIN AS THEY PASS
THROUGH. LIGHTER SHOWERS AND BKN TO OVC MID-LEVEL CIGS ARE THEN
EXPECTED TO PERSIST THROUGH THE REMAINDER OF THE NIGHT AND INTO
SUNDAY MORNING AS DEEPER MOISTURE MOVES INTO THE REGION.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
SHOWERS AND THUNDERSTORM ARE EXPECTED TO IMPACT KIPL THIS
AFTERNOON...AND KBLH EARLY THIS EVENING ARE CONVECTIVE ACTIVITY
BREAKS OUT AS A VERY MOIST AIRMASS BECOMES ENTRENCHED ACROSS THE
REGION. THESE STORMS WILL BE CAPABLE OF PRODUCING STRONG GUSTY WINDS
AND PERIODS OF HEAVY RAIN AS THEY PASS OVER THE TERMINALS. LIKELY
SHOWERS...AND PERHAPS A PERIOD OF STEADY RAIN IS LIKELY LATER
TONIGHT AND ON SUNDAY AS THE AIRMASS STABILIZES OUT...BUT STILL
REMAINS VERY MOIST...WITH BKN TO OVC MID-LEVEL CIGS WIDESPREAD OVER
THE REGION.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...
DEEP SOUTHERLY FLOW IS EXPECTED TO BRING IN ABOVE-AVERAGE AMOUNTS OF
MOISTURE INTO THE REGION THROUGH THE FORECAST PERIOD...WITH ISOLATED
TO SCATTERED THUNDERSTORMS LIKELY EACH AFTERNOON AND EVENING.
MINIMUM HUMIDITY VALUES ARE EXPECTED TO FALL INTO THE 25 TO 35
PERCENT RANGE ACROSS THE LOWER DESERTS...AND INTO THE 35 TO 45
PERCENT RANGE ACROSS THE HIGHER ELEVATIONS EACH DAY...WITH VERY GOOD
TO EXCELLENT OVERNIGHT RECOVERIES. WINDS ARE EXPECTED TO REMAIN ON
THE LIGHT SIDE...EXCEPT NEAR THUNDERSTORMS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH SUNDAY
EVENING AZZ020-021-022-025-026-027.
CA...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH SUNDAY
EVENING CAZ030>033.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...CB
PREVIOUS DISCUSSION...AJ/DEWEY
AVIATION...PERCHA/LEINS
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
910 AM MST SAT AUG 24 2013
.UPDATE...UPDATED AVIATION DISCUSSION...
&&
.SYNOPSIS...
A STORMY PERIOD IS ANTICIPATED THIS WEEKEND ACROSS THE REGION WITH
BELOW NORMAL TEMPERATURES. HEAVY RAIN AND LOCALIZED FLOODING MAY
OCCUR...ESPECIALLY ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA. PRECIPITATION CHANCES DECREASE BY EARLY NEXT WEEK...AND
INCREASED MOISTURE WILL CONTINUE THROUGH THE REMAINDER OF THE
WEEK...ALONG WITH NEAR NORMAL TEMPERATURES.
&&
.DISCUSSION...
TODAY AND SUNDAY...A BATCH OF SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED OVER THE METRO AREA EARLY THIS MORNING. LATEST RUC
IDENTIFIES A PERTURBATION MOVING THROUGH THE SOUTH-CENTRAL ARIZONA
DESERTS WHICH MIGHT ACCOUNT FOR THIS. THERE WAS A GRAVITY WAVE THAT
MOVED THROUGH BUT THAT WAS AT LEAST A FEW HOURS AGO. THE RUC SHOWS
THE PERTURBATION SHIFTING NORTH AFTER 12Z AND THUS STORM ACTIVITY
OVER MARICOPA COUNTY SHOULD WIND DOWN SHORTLY AFTER
SUNRISE...ALREADY QUIET ELSEWHERE IN THE FORECAST AREA. LARGER SCALE
FLOW FEATURES OF NOTE INCLUDE THE EVER-PRESENT TROUGH CENTERED NEAR
THE WEST COAST...A LARGE ANTICYCLONE/RIDGE CENTERED OVER THE
PLAINS...AN INVERTED TROUGH CENTERED NEAR THE CHIHUAHUA/TEXAS
BORDER...AND TROPICAL STORM IVO CENTERED WEST OF CABO SAN LUCAS. THE
MODELS HAVE DIFFERING SOLUTIONS ON HOW THE FLOW FEATURES MENTIONED
ABOVE WILL UNFOLD...PARTICULARLY THE INVERTED TROUGH AND THE BROADER
CYCLONIC CIRCULATION ASSOCIATED WITH IVO. FOR INSTANCE...THE GFS
CONTINUES TO TRACK THE IVO ASSOCIATED CIRCULATION TO THE NORTH
FASTER THAN ECWMF AND ESPECIALLY NAM. BY THAT SAME TOKEN...THE WAVE
ALSO DISSIPATES FASTER. THIS HAS IMPLICATIONS FOR TIMING OF
POPS/PRECIP. THERE ARE ALSO DIFFERENCES ON THE UPPER LEVEL
DIVERGENCE GENERATED BY THE APPROACHING WAVE WHICH ALSO IMPACTS
MODEL PRECIP FORECASTS. THOUGH THE NAM IS SLOWER WITH THE IVO
CIRCULATION...IT BRINGS IN A SMALLER WAVE LATER TODAY WHICH MIGHT BE
REMNANTS OF THE INVERTED TROUGH AND/OR A CONVECTIVELY GENERATED
FEATURE FROM SOUTHERN SONORA. THE NAM THUS PRODUCES A BATCH OF
DYNAMICAL FORCING SOONER THAN THE GFS AND ECWMF. THEY ALL SHOW A
MAJOR INFLUX OF MOISTURE. INTERESTINGLY...THERE ARE SOME
SIMILARITIES IN THE SPATIAL DISTRIBUTION OF THE QPF...INCLUDING
LOCAL WRF AND NMM6KM. MAINLY...FROM TONIGHT THROUGH SUNDAY NIGHT
THERE IS A HIGH QPF SWATH OVER WESTERN MARICOPA COUNTY AND SOUTHWEST
ARIZONA. AND A LESSER SWATH OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL
ARIZONA. IN BETWEEN IS A LOWER QPF SWATH...INCLUDING THE PHOENIX
METRO AREA. HOWEVER...THERE IS A GREAT DEAL OF VARIABILITY FOR
SOUTHEAST CALIFORNIA. THE GFS HAS ITS HEAVIEST SWATH...FOR OUR
FORECAST AREA...OVER EASTERN RIVERSIDE AND IMPERIAL COUNTIES. MADE
NUMEROUS ADJUSTMENTS TO THE QPF AND POP GRIDS. MODIFIED THE FLASH
FLOOD WATCH TO START IT 6 HOURS EARLIER AND TO EXTEND IT EASTWARD
OVER WESTERN MARICOPA COUNTY. IT SHOULD BE NOTED THAT WE WILL NOT
HAVE A TROPICAL STORM THAT BODILY MOVES INTO THE DESERT SOUTHWEST.
RATHER...TROPICAL MOISTURE WILL BE PUSHED NORTHWARD INTO THE REGION
AND THERE WILL BE FLOW FEATURES AIDING THE PRECIPITATION PRODUCTION.
ALSO...WHILE THE WATCH DOES NOT START UNTIL 06Z...THERE WILL LIKELY
BE SOME POTENT THUNDERSTORMS DEVELOPING WITHIN OUR AREA PRIOR TO
THAT. THE GFS...NAM...AND SREF ALL HAVE CAPE VALUES WELL IN EXCESS
OF 1000 J/KG...MAINLY OVER SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA. PRIOR TO THE ARRIVAL OF BROADER SCALE LIFT...ANTICIPATE
STORMS BEING MORE SCATTERED IN NATURE AS OPPOSED TO WIDESPREAD RAIN.
WITH HIGH CAPE VALUES...THERE WILL BE SEVERE POTENTIAL LATE THIS
AFTERNOON AND EVENING. THEREAFTER...ANTICIPATE DECREASING CAPE BUT
MORE WIDESPREAD SHOWERS WITH ISOLATED THUNDERSTORMS. WITH THE CLOUDS
AND RAIN COOLED AIR AROUND...SUNDAY TEMPS WILL BE WELL BELOW NORMAL.
EXTENDED PERIOD...UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND
CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM
COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT
FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL
TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE
GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES
NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY
PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN
PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF
THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO
NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA...INCLUDING KPHX...KIWA...KSDL...
OUTFLOW FROM THUNDERSTORMS OVER NORTHWEST MARICOPA COUNTY COMBINED
WITH THE USUAL DIURNAL TRENDS IS NOW EXPECTED TO KEEP WINDS OUT OF A
WESTERLY DIRECTION AT BOTH KPHX AND KSDL INTO THE AFTERNOON
HOURS...WITH WINDS AT KIWA ALSO BECOMING WESTERLY BY MIDDAY OR EARLY
AFTERNOON. THUNDERSTORMS ARE STILL POSSIBLE BY LATE AFTERNOON OR
EARLY EVENING...WITH GUSTY WINDS AND PERIODS OF HEAVY RAIN WITH THE
STRONGEST STORMS. SHOWERS ARE THEN LIKELY TO CONTINUE THROUGH THE
EVENING AND OVERNIGHT HOURS.
SOUTHEAST CALIFORNIA...INCLUDING KIPL...AND KBLH...
QUIET WEATHER EXPECTED FOR MOST OF THE DAY...WITH STORMS MOVING IN
FROM THE EAST AROUND 06Z. STRONGEST STORMS WILL BE CAPABLE OF 30+KT
WINDS AND HEAVY RAIN...BUT PINNING DOWN EXACT TIMING DIFFICULT AT
THIS POINT. SHOWERS LIKELY TO CONTINUE THROUGH THE END OF THE TAF
PERIOD.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE
EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND
SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO
MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME
LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC
MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY
AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE
TEMPERATURES TREND UPWARD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
EVENING AZZ020-021-022-025-026-027.
CA...FLASH FLOOD WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
EVENING CAZ030>033.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ/DEWEY
AVIATION...PERCHA/LEINS
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
510 AM MST SAT AUG 24 2013
.UPDATE...UPDATED AVIATION DISCUSSION...
&&
.SYNOPSIS...
A STORMY PERIOD IS ANTICIPATED THIS WEEKEND ACROSS THE REGION WITH
BELOW NORMAL TEMPERATURES. HEAVY RAIN AND LOCALIZED FLOODING MAY
OCCUR...ESPECIALLY ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA. PRECIPITATION CHANCES DECREASE BY EARLY NEXT WEEK...AND
INCREASED MOISTURE WILL CONTINUE THROUGH THE REMAINDER OF THE
WEEK...ALONG WITH NEAR NORMAL TEMPERATURES.
&&
.DISCUSSION...
TODAY AND SUNDAY...A BATCH OF SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED OVER THE METRO AREA EARLY THIS MORNING. LATEST RUC
IDENTIFIES A PERTURBATION MOVING THROUGH THE SOUTH-CENTRAL ARIZONA
DESERTS WHICH MIGHT ACCOUNT FOR THIS. THERE WAS A GRAVITY WAVE THAT
MOVED THROUGH BUT THAT WAS AT LEAST A FEW HOURS AGO. THE RUC SHOWS
THE PERTURBATION SHIFTING NORTH AFTER 12Z AND THUS STORM ACTIVITY
OVER MARICOPA COUNTY SHOULD WIND DOWN SHORTLY AFTER
SUNRISE...ALREADY QUIET ELSEWHERE IN THE FORECAST AREA. LARGER SCALE
FLOW FEATURES OF NOTE INCLUDE THE EVER-PRESENT TROUGH CENTERED NEAR
THE WEST COAST...A LARGE ANTICYCLONE/RIDGE CENTERED OVER THE
PLAINS...AN INVERTED TROUGH CENTERED NEAR THE CHIHUAHUA/TEXAS
BORDER...AND TROPICAL STORM IVO CENTERED WEST OF CABO SAN LUCAS. THE
MODELS HAVE DIFFERING SOLUTIONS ON HOW THE FLOW FEATURES MENTIONED
ABOVE WILL UNFOLD...PARTICULARLY THE INVERTED TROUGH AND THE BROADER
CYCLONIC CIRCULATION ASSOCIATED WITH IVO. FOR INSTANCE...THE GFS
CONTINUES TO TRACK THE IVO ASSOCIATED CIRCULATION TO THE NORTH
FASTER THAN ECWMF AND ESPECIALLY NAM. BY THAT SAME TOKEN...THE WAVE
ALSO DISSIPATES FASTER. THIS HAS IMPLICATIONS FOR TIMING OF
POPS/PRECIP. THERE ARE ALSO DIFFERENCES ON THE UPPER LEVEL
DIVERGENCE GENERATED BY THE APPROACHING WAVE WHICH ALSO IMPACTS
MODEL PRECIP FORECASTS. THOUGH THE NAM IS SLOWER WITH THE IVO
CIRCULATION...IT BRINGS IN A SMALLER WAVE LATER TODAY WHICH MIGHT BE
REMNANTS OF THE INVERTED TROUGH AND/OR A CONVECTIVELY GENERATED
FEATURE FROM SOUTHERN SONORA. THE NAM THUS PRODUCES A BATCH OF
DYNAMICAL FORCING SOONER THAN THE GFS AND ECWMF. THEY ALL SHOW A
MAJOR INFLUX OF MOISTURE. INTERESTINGLY...THERE ARE SOME
SIMILARITIES IN THE SPATIAL DISTRIBUTION OF THE QPF...INCLUDING
LOCAL WRF AND NMM6KM. MAINLY...FROM TONIGHT THROUGH SUNDAY NIGHT
THERE IS A HIGH QPF SWATH OVER WESTERN MARICOPA COUNTY AND SOUTHWEST
ARIZONA. AND A LESSER SWATH OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL
ARIZONA. IN BETWEEN IS A LOWER QPF SWATH...INCLUDING THE PHOENIX
METRO AREA. HOWEVER...THERE IS A GREAT DEAL OF VARIABILITY FOR
SOUTHEAST CALIFORNIA. THE GFS HAS ITS HEAVIEST SWATH...FOR OUR
FORECAST AREA...OVER EASTERN RIVERSIDE AND IMPERIAL COUNTIES. MADE
NUMEROUS ADJUSTMENTS TO THE QPF AND POP GRIDS. MODIFIED THE FLASH
FLOOD WATCH TO START IT 6 HOURS EARLIER AND TO EXTEND IT EASTWARD
OVER WESTERN MARICOPA COUNTY. IT SHOULD BE NOTED THAT WE WILL NOT
HAVE A TROPICAL STORM THAT BODILY MOVES INTO THE DESERT SOUTHWEST.
RATHER...TROPICAL MOISTURE WILL BE PUSHED NORTHWARD INTO THE REGION
AND THERE WILL BE FLOW FEATURES AIDING THE PRECIPITATION PRODUCTION.
ALSO...WHILE THE WATCH DOES NOT START UNTIL 06Z...THERE WILL LIKELY
BE SOME POTENT THUNDERSTORMS DEVELOPING WITHIN OUR AREA PRIOR TO
THAT. THE GFS...NAM...AND SREF ALL HAVE CAPE VALUES WELL IN EXCESS
OF 1000 J/KG...MAINLY OVER SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA. PRIOR TO THE ARRIVAL OF BROADER SCALE LIFT...ANTICIPATE
STORMS BEING MORE SCATTERED IN NATURE AS OPPOSED TO WIDESPREAD RAIN.
WITH HIGH CAPE VALUES...THERE WILL BE SEVERE POTENTIAL LATE THIS
AFTERNOON AND EVENING. THEREAFTER...ANTICIPATE DECREASING CAPE BUT
MORE WIDESPREAD SHOWERS WITH ISOLATED THUNDERSTORMS. WITH THE CLOUDS
AND RAIN COOLED AIR AROUND...SUNDAY TEMPS WILL BE WELL BELOW NORMAL.
EXTENDED PERIOD...UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND
CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM
COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT
FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL
TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE
GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES
NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY
PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN
PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF
THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO
NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA...INCLUDING KPHX...KIWA...KSDL...
CONDITIONS SHOULD REMAIN QUIET FOR THE REST OF THE MORNING HOURS AT
ALL PHOENIX SITES...BUT WILL DETERIORATE QUICKLY THIS AFTERNOON.
SHOWERS AND THUNDERSTORMS APPEAR POSSIBLE AS EARLY AS 21Z AND SHOULD
SWEEP THROUGH THE METRO FROM SOUTHEAST TO NORTHWEST AROUND 00Z.
TIMING DIFFICULT TO PIN DOWN AT THIS POINT...BUT EXPECT GUSTY WINDS
TO 30KTS AND PERIODS OF HEAVY RAIN WITH THE STRONGEST STORMS.
SHOWERS LIKELY TO CONTINUE THROUGH THE EVENING AND OVERNIGHT HOURS.
SOUTHEAST CALIFORNIA...INCLUDING KIPL...AND KBLH...
QUIET WEATHER EXPECTED FOR MOST OF THE DAY...WITH STORMS MOVING IN
FROM THE EAST AROUND 06Z. STRONGEST STORMS WILL BE CAPABLE OF 30+KT
WINDS AND HEAVY RAIN...BUT PINNING DOWN EXACT TIMING DIFFICULT AT
THIS POINT. SHOWERS LIKELY TO CONTINUE THROUGH THE END OF THE TAF
PERIOD.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE
EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND
SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO
MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME
LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC
MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY
AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE
TEMPERATURES TREND UPWARD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
EVENING AZZ020-021-022-025-026-027.
CA...FLASH FLOOD WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
EVENING CAZ030>033.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ/DEWEY
AVIATION...LEINS
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
445 AM MST SAT AUG 24 2013
.SYNOPSIS...
A STORMY PERIOD IS ANTICIPATED THIS WEEKEND ACROSS THE REGION WITH
BELOW NORMAL TEMPERATURES. HEAVY RAIN AND LOCALIZED FLOODING MAY
OCCUR...ESPECIALLY ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA. PRECIPITATION CHANCES DECREASE BY EARLY NEXT WEEK...AND
INCREASED MOISTURE WILL CONTINUE THROUGH THE REMAINDER OF THE
WEEK...ALONG WITH NEAR NORMAL TEMPERATURES.
&&
.DISCUSSION...
TODAY AND SUNDAY...A BATCH OF SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED OVER THE METRO AREA EARLY THIS MORNING. LATEST RUC
IDENTIFIES A PERTURBATION MOVING THROUGH THE SOUTH-CENTRAL ARIZONA
DESERTS WHICH MIGHT ACCOUNT FOR THIS. THERE WAS A GRAVITY WAVE THAT
MOVED THROUGH BUT THAT WAS AT LEAST A FEW HOURS AGO. THE RUC SHOWS
THE PERTURBATION SHIFTING NORTH AFTER 12Z AND THUS STORM ACTIVITY
OVER MARICOPA COUNTY SHOULD WIND DOWN SHORTLY AFTER
SUNRISE...ALREADY QUIET ELSEWHERE IN THE FORECAST AREA. LARGER SCALE
FLOW FEATURES OF NOTE INCLUDE THE EVER-PRESENT TROUGH CENTERED NEAR
THE WEST COAST...A LARGE ANTICYCLONE/RIDGE CENTERED OVER THE
PLAINS...AN INVERTED TROUGH CENTERED NEAR THE CHIHUAHUA/TEXAS
BORDER...AND TROPICAL STORM IVO CENTERED WEST OF CABO SAN LUCAS. THE
MODELS HAVE DIFFERING SOLUTIONS ON HOW THE FLOW FEATURES MENTIONED
ABOVE WILL UNFOLD...PARTICULARLY THE INVERTED TROUGH AND THE BROADER
CYCLONIC CIRCULATION ASSOCIATED WITH IVO. FOR INSTANCE...THE GFS
CONTINUES TO TRACK THE IVO ASSOCIATED CIRCULATION TO THE NORTH
FASTER THAN ECWMF AND ESPECIALLY NAM. BY THAT SAME TOKEN...THE WAVE
ALSO DISSIPATES FASTER. THIS HAS IMPLICATIONS FOR TIMING OF
POPS/PRECIP. THERE ARE ALSO DIFFERENCES ON THE UPPER LEVEL
DIVERGENCE GENERATED BY THE APPROACHING WAVE WHICH ALSO IMPACTS
MODEL PRECIP FORECASTS. THOUGH THE NAM IS SLOWER WITH THE IVO
CIRCULATION...IT BRINGS IN A SMALLER WAVE LATER TODAY WHICH MIGHT BE
REMNANTS OF THE INVERTED TROUGH AND/OR A CONVECTIVELY GENERATED
FEATURE FROM SOUTHERN SONORA. THE NAM THUS PRODUCES A BATCH OF
DYNAMICAL FORCING SOONER THAN THE GFS AND ECWMF. THEY ALL SHOW A
MAJOR INFLUX OF MOISTURE. INTERESTINGLY...THERE ARE SOME
SIMILARITIES IN THE SPATIAL DISTRIBUTION OF THE QPF...INCLUDING
LOCAL WRF AND NMM6KM. MAINLY...FROM TONIGHT THROUGH SUNDAY NIGHT
THERE IS A HIGH QPF SWATH OVER WESTERN MARICOPA COUNTY AND SOUTHWEST
ARIZONA. AND A LESSER SWATH OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL
ARIZONA. IN BETWEEN IS A LOWER QPF SWATH...INCLUDING THE PHOENIX
METRO AREA. HOWEVER...THERE IS A GREAT DEAL OF VARIABILITY FOR
SOUTHEAST CALIFORNIA. THE GFS HAS ITS HEAVIEST SWATH...FOR OUR
FORECAST AREA...OVER EASTERN RIVERSIDE AND IMPERIAL COUNTIES. MADE
NUMEROUS ADJUSTMENTS TO THE QPF AND POP GRIDS. MODIFIED THE FLASH
FLOOD WATCH TO START IT 6 HOURS EARLIER AND TO EXTEND IT EASTWARD
OVER WESTERN MARICOPA COUNTY. IT SHOULD BE NOTED THAT WE WILL NOT
HAVE A TROPICAL STORM THAT BODILY MOVES INTO THE DESERT SOUTHWEST.
RATHER...TROPICAL MOISTURE WILL BE PUSHED NORTHWARD INTO THE REGION
AND THERE WILL BE FLOW FEATURES AIDING THE PRECIPITATION PRODUCTION.
ALSO...WHILE THE WATCH DOES NOT START UNTIL 06Z...THERE WILL LIKELY
BE SOME POTENT THUNDERSTORMS DEVELOPING WITHIN OUR AREA PRIOR TO
THAT. THE GFS...NAM...AND SREF ALL HAVE CAPE VALUES WELL IN EXCESS
OF 1000 J/KG...MAINLY OVER SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA. PRIOR TO THE ARRIVAL OF BROADER SCALE LIFT...ANTICIPATE
STORMS BEING MORE SCATTERED IN NATURE AS OPPOSED TO WIDESPREAD RAIN.
WITH HIGH CAPE VALUES...THERE WILL BE SEVERE POTENTIAL LATE THIS
AFTERNOON AND EVENING. THEREAFTER...ANTICIPATE DECREASING CAPE BUT
MORE WIDESPREAD SHOWERS WITH ISOLATED THUNDERSTORMS. WITH THE CLOUDS
AND RAIN COOLED AIR AROUND...SUNDAY TEMPS WILL BE WELL BELOW NORMAL.
EXTENDED PERIOD...UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND
CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM
COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT
FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL
TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE
GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES
NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY
PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN
PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF
THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO
NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA...INCLUDING KPHX...KIWA...KSDL...
THUNDERSTORMS HAVE BEEN STRUGGLING WITH OUTFLOWS STALLING SHORT OF
THE TERMINAL SITES. LATEST THINKING IS SFC WINDS MAY BECOME MORE
VARIABLE BEFORE OBTAINING A PREDOMINANT EASTERLY OVERNIGHT DRIFT.
VIRGA AND LIGHT SHOWERS MAY AFFECT CNTRL ARIZONA OVERNIGHT...THOUGH
CONFIDENCE WAS FAR TOO LOW TO INCLUDE IN TAFS. SHOULD THIS
OCCUR...WINDS MAY BECOME NORTHERLY (OR MORE VARIABLE)
BRIEFLY...THOUGH CIGS SHOULD REMAIN AOA 10K FT. THUNDERSTORM AND
OUTFLOW CHANCES DIRECTLY AFFECTING TERMINAL SITES BECOME FAR HIGHER
LATE SATURDAY AFTERNOON/EVENING...BUT CONFIDENCE IS STILL SHORT OF
ADDING A TEMPO/PROB30 GROUP.
SOUTHEAST CALIFORNIA...INCLUDING KIPL...AND KBLH...
TRANQUIL CONDITIONS AND ONLY HIGH CLOUDS WILL AFFECT SERN CALIFORNIA
TERMINALS THROUGH SATURDAY AFTERNOON...WITH WINDS PREDOMINANTLY S/SE
(THOUGH SOME BRIEF PERIOD OF VARIABLE WINDS ARE POSSIBLE).
THUNDERSTORMS AND OUTFLOW MAY MORE DIRECTLY AFFECT AERODROMES LATE
SATURDAY AFTERNOON/EVENING...THOUGH OVERALL CONFIDENCE IN ADDING ANY
MENTION IN THIS TAF PACKAGE IS TOO LOW AT THIS TIME.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE
EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND
SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO
MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME
LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC
MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY
AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE
TEMPERATURES TREND UPWARD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
EVENING AZZ020-021-022-025-026-027.
CA...FLASH FLOOD WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
EVENING CAZ030>033.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ/DEWEY
AVIATION...HIRSCH
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...CORRECTED
NWS GRAND JUNCTION CO
917 PM MDT SUN AUG 25 2013
CORRECTED AVIATION DISCUSSION BELOW
.UPDATE...
ISSUED AT 906 PM MDT SUN AUG 25 2013
SHRTWV LIFTING NORTHEAST ACROSS THE FORECAST AREA THIS EVENING
SPARKING BAND OF MODERATE TO LOCALLY HEAVY SHOWERS FROM CORTEZ
NORTHEAST TO GLENWOOD SPRINGS. SOUTHERN EDGE OF THIS BAND HAS
SHOWN VERY SLOW EASTWARD PROGRESSION THIS EVENING WHILE NORTHERN
EXTENT ADVANCE A BIT QUICKER TOWARD THE EAST WITH CENTER OF
ROTATION NOW OVER WEST CENTRAL COLORADO...OR NEAR THE GRAND
VALLEY. SHALLOW NATURE OF THIS TROPICAL CONVECTION RESULTING IN
A BIT MORE OVERSHOOTING OF ECHOES THIS EVENING AND SPOTTERS
REPORTS CRUCIAL IN AREAS NEAR THE FOUR CORNERS WHERE RAINFALL
AMOUNTS VARY FROM A HALF INCH TO OVER TWO INCHES IN PORTIONS OF
SOUTHEAST UTAH. LATEST HRRR AND RAP PROMISING MORE RAIN THROUGH
THE NIGHT WITH ANOTHER PEAK SURGE ARRIVING BETWEEN 0300 AND
SUNRISE MONDAY MORNING. NO MAJOR ADJUSTMENTS NEEDED TO THE
GRIDS...ALTHOUGH WILL BE TWEAKING EARLY HOURS TO FIT CURRENT
TRENDS...RESULTING IN SOME INTERESTING POPS GRIDS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 336 PM MDT SUN AUG 25 2013
EXTENSIVE SHIELD OF MAINLY STRATIFORM PRECIPITATION HAS BEEN
LIFTING ACROSS THE CWA THROUGH THE DAY AND IS TAKING AIM NORTH OF
I-70 ATTM. THE CLOUD COVER AND MUCH COOLER TEMPERATURES HAVE
LIMITED THE CONVECTIVE POTENTIAL SO FAR...HOWEVER A BREAK UP IN
THE CLOUDS BEHIND THIS WAVE IS LEADING TO THE PRECIPITATION TAKING
ON A MORE CONVECTIVE MODE. PRECIPITATION AMOUNTS SO FAR HAVE
GENERALLY STAYED BELOW A THIRD OF AN INCH PER HOUR AND THOUGH NOT
A FLOODING THREAT...WILL LEAVE CONDITIONS FAVORABLE FOR EXCESSIVE
RUN OFF FROM THE HEAVIER CONVECTIVE SHOWERS. EFFICIENT RAINFALL
WILL CONTINUE INTO THE OVERNIGHT HOURS AS WELL AS THE MOISTURE
AXIS...RIGHT ENTRANCE REGION OF THE UPPER JET AND CHANNELIZED
VORTICITY REMAIN IN PLACE NEAR THE 4 CORNERS REGION.
ON MONDAY THE MOISTURE AXIS SHIFTS WESTWARD JUST A TAD AND SHOULD
ALLOW FOR SOME BETTER ISOLATION THROUGH THE LATE MORNING AND EARLY
AFTERNOON WHICH LEAD TO A RATHER VIGOROUS ROUND OF CONVECTION IN
FOR THE MID AND LATE AFTERNOON HOURS. PROFILES STILL SHOW PLENTY
OF SPEED SHEAR IN PLACE FOR THE AFTERNOON AND WITH DECENT WARM
CLOUD DEPTH...EFFICIENT RAINFALL PRODUCTION WILL BE ANOTHER REASON
TO KEEP FLOOD WATCH IN PLACE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 336 PM MDT SUN AUG 25 2013
12Z HAND ANALYSIS AT H5 HAD THE CENTER OF THE STRENGTHENING SUB
TROPICAL CIRCULATION OVER MISSOURI...WITH AN UPSTREAM TROF ALONG
MUCH OF THE WESTERN COAST OF NOAM. THIS PATTERN WILL REMAIN STAGNANT
THROUGH AT LEAST THE MID WEEK PERIOD BUT THERE WILL BE SUBTLE SHIFTS
OF ENERGY IN THE FLOW WHICH WILL HAVE SOME IMPACT ON THE WEATHER
ACROSS THE CENTRAL ROCKIES AND EASTERN GREAT BASIN. THE GRADIENT
OVER OUR CWA WILL BE RELAXING TUESDAY. THE WESTERN PERIPHERY OF THE
RIDGE WILL EXPANDING INTO THE ROCKIES AS ENERGY EJECTS FROM THE
COASTAL TROF AND RE-ORIENTS IT/S AXIS TO THE WEST AS WELL. THIS WILL
PULL THE MONSOONAL MOISTURE FEED JUST WEST OF OUR CWA AND THIS
SHOULD BRING A DOWNTURN TREND THE CONVECTION. HOWEVER THETA SURFACES
SHOW ANOTHER FEED OF TROPICAL MOISTURE FROM THE GULF ADVECTING
AROUND THE BASE OF THE PLAINS RIDGE...AND DIRECTED TOWARD THE
COLORADO ROCKIES ON THE EASTERLIES. THE BEST FORCING WITH THE
SHEARING WAVE WILL BE EAST OF THE DIVIDE...BUT RESIDUAL MOISTURE AND
HEATING SHOULD BE SUFFICIENT FOR A BETTER COVERAGE OF STORMS NEAR
THE DIVIDE. LIGHTER WINDS ALOFT SHOULD KEEP THE CONVECTION ROOTED TO
THE HILLS WITH MINIMAL CHANCES OF THE WESTERN VALLEYS SEEING A
PASSING STORM. RESIDUAL MOISTURE WITH PWATS FALLING TO NEAR 3/4 OF
AN INCH WEDNESDAY INTO THURSDAY WILL LEAD TO MAINLY DIURNAL
CONVECTION OVER THE MOUNTAINS. HIGHS WILL BE PUSHING BACK TO NEAR OR
ABOVE NORMAL FOR TUESDAY INTO THE LAT WEEK PERIOD.
MODELS ARE FAIRLY CONSISTENT IN PULLING THE CENTER OF THE RIDGE BACK
INTO THE SOUTHERN HIGH PLAINS NEAR THE TX PANHANDLE BY FRIDAY.
MEANWHILE THE WESTERN TROUGH WILL BE PUSHING INLAND...BOTH OF WHICH
WILL AGAIN TAP INTO THE MONSOON REGION. ATTM GFS PWATS ARE JUMPING
BACK UP TO 1.3 INCHES WHICH IS WELL ABOVE NORMAL FOR LATE AUGUST.
WILL HAVE TO WATCH THE TRENDS FOR THIS...BUT IT APPEARS WE COULD BE
HEADING INTO ANOTHER WET WEEKEND PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 918 PM MDT SUN AUG 25 2013
AREAS OF IFR/MVFR FROM VIS BELOW 3SM SHRA AND/OR CIGS BELOW BKN030
WILL CONTINUE ACROSS MUCH OF WESTERN COLORADO AND EASTERN UTAH
THROUGH 12Z MONDAY MORNING. THE MOUNTAINS AND HIGHER TERRAIN WILL
BE OCCASIONALLY OBSCURED WITH CLOUD BASES AROUND 100 MSL. BETWEEN
15Z-18Z...A LULL IN THE SHRA ACTIVITY MAY ALLOW FOR VFR AT
MOUNTAIN AIRPORTS MONDAY MORNING...BUT HEATING OF THE DAY AND A
MOIST ATMOSPHERE WILL BRING ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS FOR MONDAY AFTERNOON. THE THREAT OF GUSTY OUTFLOW
WINDS WILL INCREASE ON MONDAY AND WILL NEED TO BE MONITORED IF
NEARING FLIGHT TERMINALS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR COZ001-003-006-007-009-
011-012-014-017>023.
UT...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR UTZ022>025-027>029.
&&
$$
UPDATE...JDC
SHORT TERM...PF/15
LONG TERM...15
AVIATION...JDC/PF/15
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
916 PM MDT SUN AUG 25 2013
.UPDATE...
ISSUED AT 906 PM MDT SUN AUG 25 2013
SHRTWV LIFTING NORTHEAST ACROSS THE FORECAST AREA THIS EVENING
SPARKING BAND OF MODERATE TO LOCALLY HEAVY SHOWERS FROM CORTEZ
NORTHEAST TO GLENWOOD SPRINGS. SOUTHERN EDGE OF THIS BAND HAS
SHOWN VERY SLOW EASTWARD PROGRESSION THIS EVENING WHILE NORTHERN
EXTENT ADVANCE A BIT QUICKER TOWARD THE EAST WITH CENTER OF
ROTATION NOW OVER WEST CENTRAL COLORADO...OR NEAR THE GRAND
VALLEY. SHALLOW NATURE OF THIS TROPICAL CONVECTION RESULTING IN
A BIT MORE OVERSHOOTING OF ECHOES THIS EVENING AND SPOTTERS
REPORTS CRUCIAL IN AREAS NEAR THE FOUR CORNERS WHERE RAINFALL
AMOUNTS VARY FROM A HALF INCH TO OVER TWO INCHES IN PORTIONS OF
SOUTHEAST UTAH. LATEST HRRR AND RAP PROMISING MORE RAIN THROUGH
THE NIGHT WITH ANOTHER PEAK SURGE ARRIVING BETWEEN 0300 AND
SUNRISE MONDAY MORNING. NO MAJOR ADJUSTMENTS NEEDED TO THE
GRIDS...ALTHOUGH WILL BE TWEAKING EARLY HOURS TO FIT CURRENT
TRENDS...RESULTING IN SOME INTERESTING POPS GRIDS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 336 PM MDT SUN AUG 25 2013
EXTENSIVE SHIELD OF MAINLY STRATIFORM PRECIPITATION HAS BEEN
LIFTING ACROSS THE CWA THROUGH THE DAY AND IS TAKING AIM NORTH OF
I-70 ATTM. THE CLOUD COVER AND MUCH COOLER TEMPERATURES HAVE
LIMITED THE CONVECTIVE POTENTIAL SO FAR...HOWEVER A BREAK UP IN
THE CLOUDS BEHIND THIS WAVE IS LEADING TO THE PRECIPITATION TAKING
ON A MORE CONVECTIVE MODE. PRECIPITATION AMOUNTS SO FAR HAVE
GENERALLY STAYED BELOW A THIRD OF AN INCH PER HOUR AND THOUGH NOT
A FLOODING THREAT...WILL LEAVE CONDITIONS FAVORABLE FOR EXCESSIVE
RUN OFF FROM THE HEAVIER CONVECTIVE SHOWERS. EFFICIENT RAINFALL
WILL CONTINUE INTO THE OVERNIGHT HOURS AS WELL AS THE MOISTURE
AXIS...RIGHT ENTRANCE REGION OF THE UPPER JET AND CHANNELIZED
VORTICITY REMAIN IN PLACE NEAR THE 4 CORNERS REGION.
ON MONDAY THE MOISTURE AXIS SHIFTS WESTWARD JUST A TAD AND SHOULD
ALLOW FOR SOME BETTER ISOLATION THROUGH THE LATE MORNING AND EARLY
AFTERNOON WHICH LEAD TO A RATHER VIGOROUS ROUND OF CONVECTION IN
FOR THE MID AND LATE AFTERNOON HOURS. PROFILES STILL SHOW PLENTY
OF SPEED SHEAR IN PLACE FOR THE AFTERNOON AND WITH DECENT WARM
CLOUD DEPTH...EFFICIENT RAINFALL PRODUCTION WILL BE ANOTHER REASON
TO KEEP FLOOD WATCH IN PLACE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 336 PM MDT SUN AUG 25 2013
12Z HAND ANALYSIS AT H5 HAD THE CENTER OF THE STRENGTHENING SUB
TROPICAL CIRCULATION OVER MISSOURI...WITH AN UPSTREAM TROF ALONG
MUCH OF THE WESTERN COAST OF NOAM. THIS PATTERN WILL REMAIN STAGNANT
THROUGH AT LEAST THE MID WEEK PERIOD BUT THERE WILL BE SUBTLE SHIFTS
OF ENERGY IN THE FLOW WHICH WILL HAVE SOME IMPACT ON THE WEATHER
ACROSS THE CENTRAL ROCKIES AND EASTERN GREAT BASIN. THE GRADIENT
OVER OUR CWA WILL BE RELAXING TUESDAY. THE WESTERN PERIPHERY OF THE
RIDGE WILL EXPANDING INTO THE ROCKIES AS ENERGY EJECTS FROM THE
COASTAL TROF AND RE-ORIENTS IT/S AXIS TO THE WEST AS WELL. THIS WILL
PULL THE MONSOONAL MOISTURE FEED JUST WEST OF OUR CWA AND THIS
SHOULD BRING A DOWNTURN TREND THE CONVECTION. HOWEVER THETA SURFACES
SHOW ANOTHER FEED OF TROPICAL MOISTURE FROM THE GULF ADVECTING
AROUND THE BASE OF THE PLAINS RIDGE...AND DIRECTED TOWARD THE
COLORADO ROCKIES ON THE EASTERLIES. THE BEST FORCING WITH THE
SHEARING WAVE WILL BE EAST OF THE DIVIDE...BUT RESIDUAL MOISTURE AND
HEATING SHOULD BE SUFFICIENT FOR A BETTER COVERAGE OF STORMS NEAR
THE DIVIDE. LIGHTER WINDS ALOFT SHOULD KEEP THE CONVECTION ROOTED TO
THE HILLS WITH MINIMAL CHANCES OF THE WESTERN VALLEYS SEEING A
PASSING STORM. RESIDUAL MOISTURE WITH PWATS FALLING TO NEAR 3/4 OF
AN INCH WEDNESDAY INTO THURSDAY WILL LEAD TO MAINLY DIURNAL
CONVECTION OVER THE MOUNTAINS. HIGHS WILL BE PUSHING BACK TO NEAR OR
ABOVE NORMAL FOR TUESDAY INTO THE LAT WEEK PERIOD.
MODELS ARE FAIRLY CONSISTENT IN PULLING THE CENTER OF THE RIDGE BACK
INTO THE SOUTHERN HIGH PLAINS NEAR THE TX PANHANDLE BY FRIDAY.
MEANWHILE THE WESTERN TROUGH WILL BE PUSHING INLAND...BOTH OF WHICH
WILL AGAIN TAP INTO THE MONSOON REGION. ATTM GFS PWATS ARE JUMPING
BACK UP TO 1.3 INCHES WHICH IS WELL ABOVE NORMAL FOR LATE AUGUST.
WILL HAVE TO WATCH THE TRENDS FOR THIS...BUT IT APPEARS WE COULD BE
HEADING INTO ANOTHER WET WEEKEND PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 336 PM MDT SUN AUG 25 2013
AREAS OF IFR/MVFR FROM VIS BELOW 3SM SHRA AND/OR CIGS BELOW BKN030
WILL CONTINUE ACROSS MUCH OF WESTERN COLORADO AND EASTERN UTAH
THROUGH 12Z MONDAY MORNING. THE MOUNTAINS AND HIGHER TERRAIN WILL
BE OCCASIONALLY OBSCURED WITH CLOUD BASES AROUND 100 MSL. BETWEEN
15Z-18Z...A LULL IN THE SHRA ACTIVITY MAY ALLOW FOR VFR AT
MOUNTAIN AIRPORTS MONDAY MORNING...BUT HEATING OF THE DAY AND A
MOIST ATMOSPHERE WILL BRING ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS FOR MONDAY AFTERNOON. THE THREAT OF GUSTY OUTFLOW
WINDS WILL INCREASE ON MONDAY AND WILL NEED TO BE MONITORED IF
NEARING FLIGHT TERMINALS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR COZ001-003-006-007-009-
011-012-014-017>023.
UT...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR UTZ022>025-027>029.
&&
$$
UPDATE...JDC
SHORT TERM...PF/15
LONG TERM...15
AVIATION...JDC/PF/15
AREA FORECAST DISCUSSION
NWS ALBANY NY
740 PM EDT SUN AUG 25 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE NORTHEAST WILL DRIFT TO THE CAROLINAS...AND
SETTLE THERE FOR SEVERAL DAYS. ITS RETURN SOUTHWESTERLY FLOW WILL
BRING SURGES OF INCREASINGLY WARM AND HUMID AIR INTO THE
REGION...EACH ACCOMPANIED BY A ROUND OF SHOWERS OR THUNDERSTORMS.
THE FIRST OF THESE WILL BE LATE TONIGHT INTO MONDAY...THE NEXT
WEDNESDAY INTO THURSDAY. BY WEEKS END HIGH PRESSURE WILL BE ANCHORED
ALONG THE ATLANTIC SEABOARD BRINGING WARM...HUMID WEATHER WITH
SCATTERED THUNDERSTORMS.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 700 PM EDT...REGIONAL RADARS WERE FOLLOWING A COUPLE OF
BATCHES OF SHOWERS ASSOCIATED WITH A SERIES OF MESO-SCALE
CONVECTIVE COMPLEXES (MCC). ONE IN ONTARIO CANADA WAS ACTUALLY
WORKING IT WAS OVER INTO UPSTATE NORTHWESTERN NY STATE NEAR
WATERTOWN. AS THIS FIRST ENCOUNTERS FAIRLY DRY AIR WITH DEWPOINTS
STILL IN THE 50S (ALBEIT THEY ARE CREEPING UPWARD)...THIS FIRST
BATCH IS EXPECTED TO DISSIPATE AS IT MOVES INTO HERKIMER COUNTY...OR
AT THE VERY WORST...HAVE SOME SPRINKLES.
THIS WAS THE RESULT OF WARM AIR ADVECTION...BEING ENHANCED BY THE
NOSE OF AN INCREASING LOW LEVEL JET.
THERE WAS ANOTHER SECOND MCC FURTHER UPSTREAM TO THE NORTHEAST OF
MICHIGAN WITH MUCH COLDER CLOUD TOPS AND PLENTY OF CLOUD TO GROUND
LIGHTING STRIKES (CG). THIS IS THE THE COMPLEX THAT WILL LIKELY
PRODUCE SOME SHOWERS (AND POSSIBLY A THUNDERSTORM) MAINLY TO THE
NORTH AND WEST OF ALBANY LATER OVERNIGHT.
SURFACE HIGH PRESSURE HAS RETREATED OFF SHORE...CREATING AN
INCREASINGLY SW FLOW ALOFT. LATER ON OVERNIGHT...HIGH RESOLUTION
MODELS STILL INDICATE AN H850-H700 THETA E RIDGE POKING INTO OUR
AREA BY DAWN ALONG WITH WINDS UP 40 KTS AT THE H850 LEVEL.
FOR THIS UPDATE WE SPED UP THE ARRIVAL OF THE MCC A
LITTLE...BUMPING POPS UP ABOUT 10 POINTS FROM ALBANY NORTHWARD. ONE
THING TO WATCH IS THE LATEST EXPERIMENTAL HRRR AND HI RESOLUTION WRF
MODELS BOTH ATTEMPT TO BRING MEASURABLE RAIN SHOWERS TO THE CAPITAL
DISTRICT AS EARLY AS 900 PM. WE DO THINK THIS IS TOO FAST...BUT THE
OPERATIONAL MODELS WHICH HAVE THE RAIN COMING TOWARD DAYBREAK ARE
LIKELY A LITTLE SLOW. A COMPROMISE IN TIMING WAS THE BEST WAY TO GO.
THERE IS STILL LOW CONFIDENCE ON HOW UNSTABLE THE COLUMN WILL BE
WHEN THE MCC ARRIVES. THE LATEST NAM INDICATED VERY LITTLE IF ANY
INSTABILITY. HOWEVER...ELEVATED INSTABILITY IS ALWAYS A POSSIBILITY
AND FOR NOW...WILL JUST CALL IT A SLIGHT CHANCE OF THUNDERSTORMS
OVERNIGHT. RAINFALL AMOUNTS WITH THIS MCC COULD RANGE FROM WELL OVER
A QUARTER OF AN INCH NORTHWEST OF ALBANY...TO LITTLE OR NONE WELL
SOUTH OF THE CAPITAL DISTRICT.
BASED ON AN INCREASE IN CLOUD COVER A LITTLE FASTER THAN THE
PREVIOUS FORECAST...RAISED OVERNIGHT MINIMUM TEMPERATURES ABOUT TWO
DEGREES ACROSS THE BOARD. OVERNIGHT LOWS WILL RANGE FROM AROUND 60
IN THE CAPITAL REGION...TO GENERALLY MID TO UPPER 50S ACROSS MOST OF
THE REMAINDER OF THE FORECAST AREA OF EASTERN NEW YORK AND ADJACENT
WESTERN NEW ENGLAND.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
THE REGION WILL BE IN THE 500HPA FLOW OVER THE TOP OF THE MASSIVE
500HPA RIDGE...AS THE RIDGE CENTER DRIFTS FM THE MID MISS VLY TO THE
SOUTHERN PLAINS DURING THIS PERIOD. SEVERAL 500HPA SHORT WAVES WILL
MOVE OVER THE TOP OF THE RIDGE TWRD FCA THE NEXT FEW DAYS.
THE FIRST SHORT WV IS CURRENTLY IN S ONTARIO...AND WILL ARRIVE LATE
TNGT AND TWRD DAYBREAK MONDAY. IT WILL BE ACCOMPANIED BY A WMFNT
AND SURGE OF 340-350 THETA AIR ON A 30-40KT 850HPA JET. PW WILL INCR
QUICKLY OVERNIGHT FM UNDER 0.75 TO JUST SHY OF 2 INCHES. AN MCS IS
ASSOC WITH THIS FEATURE ATTM OVR THE UPR GREAT LAKES AND IS
PROPAGATING SE TWRD FCA. MODEL BEST CAPE (SINCE THIS SYSTEM WILL BE
WORKING WITH ELEVATED CAPE WILL BE ON THE ORDER OF 1000-1600 J/KG
OVR RGN BY DAYBREAK. SPC HAS N HALF OF FCA IN IN GEN THUNDERSTORMS
OUTLOOK.
LOCAL WRF BRINGS MCS TO NY/QB BORDER BY 08UTC...INTO ADIRONDACKS
09-12UTC...MHWK VLY 11-13UTC...AND INTO S TIER OF FCA DURING MORNING
MON. THE NAM IS A TAD FASTER...THE GFS ABOUT SAME AS WRF AND HRRR
4-5 HRS FASTER.
IN ANY CASE A PERIOD OF SHRA AND TSTMS...SOME WITH HVY DOWNPOURS
AND FREQUENT LIGHTING WILL GREET MANY ACROSS FCA DURING THE WEE AND
MORNING HOURS MON. LOW TEMPS TNGT WILL STILL BE IN THE 50S.
WHILE THE INITIAL MCS WILL BE WEAKENING IN THE MORNING HRS...THE
WMFNT AND DIURNAL CYCLE WILL FOCUS MORE CONVECTION...PARTICULARLY
IN THE AFTN AS TD RISE INTO THE 60S AND SOME BREAKS OF SUN OCCUR.
NAM CAPES REBOUND TO 1000-2000 J/KG...OVERDONE...BUT EVEN IT AT
HALF THOSE WILL BE SUFFICIENT FOR GOOD TSTM DEV. 850-700HPA LAPSE
RATES NOT TOO FAVOR AT 5.5C. EHI INCRG TO 0.5 TO 2.0 BY AFTN.
HI TEMPS WILL REACH MID 70S TO AROUND 80...BUT WITH TD HEADING
TWRD 70 IT WILL BE MUGGY.
MON NT THE WMFNT WILL BE NW-SE ACROSS FCA...AS 500HPA SHORT WV
EXITS RGN AND WK RIDGING BEHIND IT SETS UP FOR TUE. SCT EVENING
CONVECTION WILL END...AND A MUGGY NIGHT WILL FOLLOW WITH LOWS IN
THE 60S AND TD ABOUT THE SAME. PATCHY TO AREAS OF FOG ARE
EXPECTED.
TUESDAY WILL BE THE DAY BETWEEN 500HPA SHORT WAVES...AND SUFFICIENT
DRYING AND MIXING IN MOIST AIRMASS SHOULD OCCUR TO ALLOW SKIES TO
BECOMING PC AND TEMP WILL RISE INTO THE 80S TO NEAR 90. TD WILL BE
IN THE MID MID 60S TO 70.
BY TUE EVENING NEXT SHORT WV IS FLYING AT US IN FAST NW FLOW AND IT
WILL FOCUS ANOTHER ROUND OF CONVECTION WED. THIS ONE IS ACCOMPANYING
BY A SFC WAVE ON WMFNT. THE GFS AND HALF ITS ENSEMBLE BRING THIS
ACTIVITY IN LATE TUES NT...THE GEM/NAM AND SREF ENSEMBLE ALL HOLD
OFF TILL WED. WILL KEEP ALL BUT SLIGHT CHC OUT OF TUES NT.
IN SUCH A MOISTURE RICH AIR MASS HEAVY DOWNPOURS REMAIN A THREAT
IN SOME OF THESE STORMS. HWVR THE MID LVL FLOW SHOULD KEEP THEM
MOVING ALONG.
WITH MORE CLOUDS AND -SHRA/TSTM WED WILL BE A BIT COOLER WITH
HIGHS AROUND 80. HUMIDITY WILL REMAIN HIGH AS TD CONTINUE TO HOVER
AROUND 70.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE EXTENDED FORECAST PERIOD FEATURES THE PERSISTENT 500HPA RIDGE
OVER THE GREAT PLAINS AND A TROF ALONG THE E COAST AT THE START.
THIS TROF AND ITS ASSOC WK SFC LOW BROUGHT WED -SHRA/TSTMS...AND AS
IT DEPARTS WILL KEEP CHC POPS INTO THU MORNING.
BEYOND THAT 500HPA RIDGE GRADUALLY SHIFTS BACK TO EAST COAST BY END
OF EXTENDED FORECAST PERIOD. FOR MOST OF PD FCA REMAINS ON NW FLOW
SIDE OF RIDGE IN THE RING OF FIRE. THE ECMWF BRINGS A TROF AND SCT
CONVECTION SAT. THE GEM AND GFS BRING ANOTHER SHORT WV DOWN THE FLOW
THU NT AND FRI...THE GFS EVEN PRODUCES -SHRA ACCOMPANIED THIS AND
ANOTHER WK CDFNT. HPC ENDS ALL CHC POPS OVR FCA WITH THUR MORNINGS
SYSTEM. SO A WARM HUMID PERIOD. TIMING PCPN OUTSIDE DIURNAL CYCLE
WILL BE DIFFICULT. BUT IT WILL BE DRY MOST OF THE TIME.
AT SFC FCA ON PERIPHERY OF CANADIAN HIGH THAT MOVES FM ONT/QB
FRI...TO E SEABOARD FOR THE WEEKEND. TEMPERATURES WILL BE ABOVE
NORMALS...TRENDING UPWARD WITH TIME. WILL POPULATE WITH HPC...AND
MODIFY FOR CHC TSTMS AS NEEDED THAT ARE HARD TO TIME
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AT 730 PM EDT...RADARS INDICATED SOME SHOWERS WORKING TO OUR WEST.
EVEN SO...WE ARE ANTICIPATING NO AVIATION WEATHER RELATED PROBLEMS
THROUGH THE EVENING WITH NOTHING MORE THAN A POSSIBLE SPRINKLE AT
KGFL WITH OTHERWISE PREDOMINATING VFR CONDITIONS. HIGH CLOUDS WILL
TEND TO LOWER BUT REMAIN WELL OVER 3000 FEET.
OVERNIGHT...AS MOISTURE CONTINUES TO INCREASE...THE RISK OF SHOWERS
WILL AS WELL. WE ASSIGNED A VCSH TO ALL THE TAFS BY MIDNIGHT (EXCEPT
KPOU) BUT KEEP CONDITIONS VFR. HOWEVER...BY 07Z WE INCLUDE SHOWERS
LOWERING CONDITIONS TO MVFR AT KALB (A LITTLE EARLIER AT KGFL AND A
LITTLE LATER AT KPSF). AT KPOU...THE FIRST BATCH OF SHOWERS MIGHT
NEVER MAKE IT THAT FAR SOUTH.
MONDAY...HUMIDITY WILL INCREASE AND CIGS LOOK TO PERSIST. THEY ARE
EXPECTED TO MAINLY BE IN THE VFR RANGE. ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS ARE POSSIBLE LATER IN THE AFTERNOON AND THIS INCLUDES
KPOU. FOR NOW...DID ASSIGN A PROB30 GROUP FROM 16Z-22Z TO REFLECT A
MODEST CONFIDENCE (30-40 PERCENT) THAT THUNDERSTORMS AND OR RAIN
INDUCED FOG/LOW CLOUDS COULD TAKE CONDITIONS TO THE HIGH END OF VFR
UP TO HALF OF THE TIME FROM 16Z-22Z.
OUTSIDE OF ANY THUNDERSTORMS...SURFACE WIND WILL NOT BE A PROBLEM
LIGHT SOUTHERLY OVERNIGHT...BECOMING S OR SW AROUND NEAR 10KTS ON
MONDAY.
THE WINDS WILL BE SOUTHEAST TO SOUTHWEST AT 5-10 KTS THIS AFTERNOON
AND THEN BECOME LIGHT AND VARIABLE TONIGHT AND SOUTH TO SOUTHWEST AT
5-10 KTS ON MONDAY.
OUTLOOK...
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...FG...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF
SHRA...TSRA.
TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...FG...TSRA.
WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...TSRA.
WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
THURSDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
A WARM FRONT WILL APPROACH FROM THE WEST MONDAY BRINGING A PERIOD
OF SHOWERS AND THUNDERSTORMS TO THE AREA. OUR WEATHER WILL BE
UNSETTLED THROUGH MID WEEK AS A LOW PRESSURE SYSTEM APPROACHES AND
MOVES ACROSS THE REGION.
RELATIVE HUMIDITY VALUES WILL RECOVER TO NEAR 100 PERCENT TONIGHT
AND MONDAY NIGHT. ON MONDAY AND TUESDAY MINIMUMS WILL BE ABOVE 50
PERCENT.
&&
.HYDROLOGY...
SHOWERS AND THUNDERSTORMS ARE EXPECTED LATE TONIGHT AND
MONDAY...AND AGAIN WEDNESDAY.
RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE RANGING FROM A QUARTER OR
MORE INCHES NORTH AND WEST
NO WIDESPREAD HYDRO PROBLEMS ARE
EXPECTED THIS WEEK. PRECIPITATION AMOUNTS WILL BE HIGHLY VARIABLE
DEPENDING ON WHERE CONVECTION OCCUR. POSSIBLY ALMOST 2 INCHES
MONDAY SO SOME HEAVY DOWNPOURS ARE EXPECTED. OVERALL RIVER FLOWS
AND RESERVOIR LEVELS CONTINUE AT NORMAL TO SLIGHTLY BELOW NORMAL
LEVELS FOR LATE AUGUST.
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...SNYDER
NEAR TERM...HWJIV/SNYDER
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...HWJIV
FIRE WEATHER...SNYDER
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
715 PM EDT SUN AUG 25 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE NORTHEAST WILL DRIFT TO THE CAROLINAS...AND
SETTLE THERE FOR SEVERAL DAYS. ITS RETURN SOUTHWESTERLY FLOW WILL
BRING SURGES OF INCREASINGLY WARM AND HUMID AIR INTO THE
REGION...EACH ACCOMPANIED BY A ROUND OF SHOWERS OR THUNDERSTORMS.
THE FIRST OF THESE WILL BE LATE TONIGHT INTO MONDAY...THE NEXT
WEDNESDAY INTO THURSDAY. BY WEEKS END HIGH PRESSURE WILL BE ANCHORED
ALONG THE ATLANTIC SEABOARD BRINGING WARM...HUMID WEATHER WITH
SCATTERED THUNDERSTORMS.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 700 PM EDT...REGIONAL RADARS WERE FOLLOWING A COUPLE OF
BATCHES OF SHOWERS ASSOCIATED WITH A SERIES OF MESO-SCALE
CONVECTIVE COMPLEXES (MCC). ONE IN ONTARIO CANADA WAS ACTUALLY
WORKING IT WAS OVER INTO UPSTATE NORTHWESTERN NY STATE NEAR
WATERTOWN. AS THIS FIRST ENCOUNTERS FAIRLY DRY AIR WITH DEWPOINTS
STILL IN THE 50S (ALBEIT THEY ARE CREEPING UPWARD)...THIS FIRST
BATCH IS EXPECTED TO DISSIPATE AS IT MOVES INTO HERKIMER COUNTY...OR
AT THE VERY WORST...HAVE SOME SPRINKLES.
THIS WAS THE RESULT OF WARM AIR ADVECTION...BEING ENHANCED BY THE
NOSE OF AN INCREASING LOW LEVEL JET.
THERE WAS ANOTHER SECOND MCC FURTHER UPSTREAM TO THE NORTHEAST OF
MICHIGAN WITH MUCH COLDER CLOUD TOPS AND PLENTY OF CLOUD TO GROUND
LIGHTING STRIKES (CG). THIS IS THE THE COMPLEX THAT WILL LIKELY
PRODUCE SOME SHOWERS (AND POSSIBLY A THUNDERSTORM) MAINLY TO THE
NORTH AND WEST OF ALBANY LATER OVERNIGHT.
SURFACE HIGH PRESSURE HAS RETREATED OFF SHORE...CREATING AN
INCREASINGLY SW FLOW ALOFT. LATER ON OVERNIGHT...HIGH RESOLUTION
MODELS STILL INDICATE AN H850-H700 THETA E RIDGE POKING INTO OUR
AREA BY DAWN ALONG WITH WINDS UP 40 KTS AT THE H850 LEVEL.
FOR THIS UPDATE WE SPED UP THE ARRIVAL OF THE MCC A
LITTLE...BUMPING POPS UP ABOUT 10 POINTS FROM ALBANY NORTHWARD. ONE
THING TO WATCH IS THE LATEST EXPERIMENTAL HRRR AND HI RESOLUTION WRF
MODELS BOTH ATTEMPT TO BRING MEASURABLE RAIN SHOWERS TO THE CAPITAL
DISTRICT AS EARLY AS 900 PM. WE DO THINK THIS IS TOO FAST...BUT THE
OPERATIONAL MODELS WHICH HAVE THE RAIN COMING TOWARD DAYBREAK ARE
LIKELY A LITTLE SLOW. A COMPROMISE IN TIMING WAS THE BEST WAY TO GO.
THERE IS STILL LOW CONFIDENCE ON HOW UNSTABLE THE COLUMN WILL BE
WHEN THE MCC ARRIVES. THE LATEST NAM INDICATED VERY LITTLE IF ANY
INSTABILITY. HOWEVER...ELEVATED INSTABILITY IS ALWAYS A POSSIBILITY
AND FOR NOW...WILL JUST CALL IT A SLIGHT CHANCE OF THUNDERSTORMS
OVERNIGHT. RAINFALL AMOUNTS WITH THIS MCC COULD RANGE FROM WELL OVER
A QUARTER OF AN INCH NORTHWEST OF ALBANY...TO LITTLE OR NONE WELL
SOUTH OF THE CAPITAL DISTRICT.
BASED ON AN INCREASE IN CLOUD COVER A LITTLE FASTER THAN THE
PREVIOUS FORECAST...RAISED OVERNIGHT MINIMUM TEMPERATURES ABOUT TWO
DEGREES ACROSS THE BOARD. OVERNIGHT LOWS WILL RANGE FROM AROUND 60
IN THE CAPITAL REGION...TO GENERALLY MID TO UPPER 50S ACROSS MOST OF
THE REMAINDER OF THE FORECAST AREA OF EASTERN NEW YORK AND ADJACENT
WESTERN NEW ENGLAND.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
THE REGION WILL BE IN THE 500HPA FLOW OVER THE TOP OF THE MASSIVE
500HPA RIDGE...AS THE RIDGE CENTER DRIFTS FM THE MID MISS VLY TO THE
SOUTHERN PLAINS DURING THIS PERIOD. SEVERAL 500HPA SHORT WAVES WILL
MOVE OVER THE TOP OF THE RIDGE TWRD FCA THE NEXT FEW DAYS.
THE FIRST SHORT WV IS CURRENTLY IN S ONTARIO...AND WILL ARRIVE LATE
TNGT AND TWRD DAYBREAK MONDAY. IT WILL BE ACCOMPANIED BY A WMFNT
AND SURGE OF 340-350 THETA AIR ON A 30-40KT 850HPA JET. PW WILL INCR
QUICKLY OVERNIGHT FM UNDER 0.75 TO JUST SHY OF 2 INCHES. AN MCS IS
ASSOC WITH THIS FEATURE ATTM OVR THE UPR GREAT LAKES AND IS
PROPAGATING SE TWRD FCA. MODEL BEST CAPE (SINCE THIS SYSTEM WILL BE
WORKING WITH ELEVATED CAPE WILL BE ON THE ORDER OF 1000-1600 J/KG
OVR RGN BY DAYBREAK. SPC HAS N HALF OF FCA IN IN GEN THUNDERSTORMS
OUTLOOK.
LOCAL WRF BRINGS MCS TO NY/QB BORDER BY 08UTC...INTO ADIRONDACKS
09-12UTC...MHWK VLY 11-13UTC...AND INTO S TIER OF FCA DURING MORNING
MON. THE NAM IS A TAD FASTER...THE GFS ABOUT SAME AS WRF AND HRRR
4-5 HRS FASTER.
IN ANY CASE A PERIOD OF SHRA AND TSTMS...SOME WITH HVY DOWNPOURS
AND FREQUENT LIGHTING WILL GREET MANY ACROSS FCA DURING THE WEE AND
MORNING HOURS MON. LOW TEMPS TNGT WILL STILL BE IN THE 50S.
WHILE THE INITIAL MCS WILL BE WEAKENING IN THE MORNING HRS...THE
WMFNT AND DIURNAL CYCLE WILL FOCUS MORE CONVECTION...PARTICULARLY
IN THE AFTN AS TD RISE INTO THE 60S AND SOME BREAKS OF SUN OCCUR.
NAM CAPES REBOUND TO 1000-2000 J/KG...OVERDONE...BUT EVEN IT AT
HALF THOSE WILL BE SUFFICIENT FOR GOOD TSTM DEV. 850-700HPA LAPSE
RATES NOT TOO FAVOR AT 5.5C. EHI INCRG TO 0.5 TO 2.0 BY AFTN.
HI TEMPS WILL REACH MID 70S TO AROUND 80...BUT WITH TD HEADING
TWRD 70 IT WILL BE MUGGY.
MON NT THE WMFNT WILL BE NW-SE ACROSS FCA...AS 500HPA SHORT WV
EXITS RGN AND WK RIDGING BEHIND IT SETS UP FOR TUE. SCT EVENING
CONVECTION WILL END...AND A MUGGY NIGHT WILL FOLLOW WITH LOWS IN
THE 60S AND TD ABOUT THE SAME. PATCHY TO AREAS OF FOG ARE
EXPECTED.
TUESDAY WILL BE THE DAY BETWEEN 500HPA SHORT WAVES...AND SUFFICIENT
DRYING AND MIXING IN MOIST AIRMASS SHOULD OCCUR TO ALLOW SKIES TO
BECOMING PC AND TEMP WILL RISE INTO THE 80S TO NEAR 90. TD WILL BE
IN THE MID MID 60S TO 70.
BY TUE EVENING NEXT SHORT WV IS FLYING AT US IN FAST NW FLOW AND IT
WILL FOCUS ANOTHER ROUND OF CONVECTION WED. THIS ONE IS ACCOMPANYING
BY A SFC WAVE ON WMFNT. THE GFS AND HALF ITS ENSEMBLE BRING THIS
ACTIVITY IN LATE TUES NT...THE GEM/NAM AND SREF ENSEMBLE ALL HOLD
OFF TILL WED. WILL KEEP ALL BUT SLIGHT CHC OUT OF TUES NT.
IN SUCH A MOISTURE RICH AIR MASS HEAVY DOWNPOURS REMAIN A THREAT
IN SOME OF THESE STORMS. HWVR THE MID LVL FLOW SHOULD KEEP THEM
MOVING ALONG.
WITH MORE CLOUDS AND -SHRA/TSTM WED WILL BE A BIT COOLER WITH
HIGHS AROUND 80. HUMIDITY WILL REMAIN HIGH AS TD CONTINUE TO HOVER
AROUND 70.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE EXTENDED FORECAST PERIOD FEATURES THE PERSISTENT 500HPA RIDGE
OVER THE GREAT PLAINS AND A TROF ALONG THE E COAST AT THE START.
THIS TROF AND ITS ASSOC WK SFC LOW BROUGHT WED -SHRA/TSTMS...AND AS
IT DEPARTS WILL KEEP CHC POPS INTO THU MORNING.
BEYOND THAT 500HPA RIDGE GRADUALLY SHIFTS BACK TO EAST COAST BY END
OF EXTENDED FORECAST PERIOD. FOR MOST OF PD FCA REMAINS ON NW FLOW
SIDE OF RIDGE IN THE RING OF FIRE. THE ECMWF BRINGS A TROF AND SCT
CONVECTION SAT. THE GEM AND GFS BRING ANOTHER SHORT WV DOWN THE FLOW
THU NT AND FRI...THE GFS EVEN PRODUCES -SHRA ACCOMPANIED THIS AND
ANOTHER WK CDFNT. HPC ENDS ALL CHC POPS OVR FCA WITH THUR MORNINGS
SYSTEM. SO A WARM HUMID PERIOD. TIMING PCPN OUTSIDE DIURNAL CYCLE
WILL BE DIFFICULT. BUT IT WILL BE DRY MOST OF THE TIME.
AT SFC FCA ON PERIPHERY OF CANADIAN HIGH THAT MOVES FM ONT/QB
FRI...TO E SEABOARD FOR THE WEEKEND. TEMPERATURES WILL BE ABOVE
NORMALS...TRENDING UPWARD WITH TIME. WILL POPULATE WITH HPC...AND
MODIFY FOR CHC TSTMS AS NEEDED THAT ARE HARD TO TIME
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL SLIDE SOUTH THROUGH THE MID ATLANTIC REGION
AND INTO THE SOUTHEAST STATES LATE TONIGHT. AN UPPER LEVEL
DISTURBANCE WILL BRING SOME SHOWERS AND THUNDERSTORMS TO THE FCST
AREA FOR MONDAY.
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE TAF SITES UNTIL LATE
TONIGHT WITH SOME SCT-BKN CIRRUS AROUND IN THE LATE AFTERNOON INTO
THE EARLY EVENING. THE CLOUDS WILL THICKEN AND GRADUALLY LOWER AFTER
MIDNIGHT AHEAD OF A WARM FRONT. SHOWERS AND PERHAPS A FEW
THUNDERSTORMS WILL ARRIVE LATE TONIGHT INTO MONDAY MORNING RESULTING
IN MVFR CONDITIONS AT THE TAF SITES.
THE WINDS WILL BE SOUTHEAST TO SOUTHWEST AT 5-10 KTS THIS AFTERNOON
AND THEN BECOME LIGHT AND VARIABLE TONIGHT AND SOUTH TO SOUTHWEST AT
5-10 KTS ON MONDAY.
OUTLOOK...
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...FG...TSRA. TUESDAY: NO OPERATIONAL IMPACT. SLIGHT CHANCE OF
SHRA...TSRA. TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...FG...TSRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...TSRA. WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA. THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
THURSDAY NIGHT AND FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
A WARM FRONT WILL APPROACH FROM THE WEST MONDAY BRINGING A PERIOD
OF SHOWERS AND THUNDERSTORMS TO THE AREA. OUR WEATHER WILL BE
UNSETTLED THROUGH MID WEEK AS A LOW PRESSURE SYSTEM APPROACHES AND
MOVES ACROSS THE REGION.
RELATIVE HUMIDITY VALUES WILL RECOVER TO NEAR 100 PERCENT TONIGHT
AND MONDAY NIGHT. ON MONDAY AND TUESDAY MINIMUMS WILL BE ABOVE 50
PERCENT.
&&
.HYDROLOGY...
SHOWERS AND THUNDERSTORMS ARE EXPECTED LATE TONIGHT AND
MONDAY...AND AGAIN WEDNESDAY.
RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE RANGING FROM A QUARTER OR
MORE INCHES NORTH AND WEST
NO WIDESPREAD HYDRO PROBLEMS ARE
EXPECTED THIS WEEK. PRECIPITATION AMOUNTS WILL BE HIGHLY VARIABLE
DEPENDING ON WHERE CONVECTION OCCUR. POSSIBLY ALMOST 2 INCHES
MONDAY SO SOME HEAVY DOWNPOURS ARE EXPECTED. OVERALL RIVER FLOWS
AND RESERVOIR LEVELS CONTINUE AT NORMAL TO SLIGHTLY BELOW NORMAL
LEVELS FOR LATE AUGUST.
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...SNYDER
NEAR TERM...HWJIV
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...11
FIRE WEATHER...SNYDER
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
931 PM EDT SUN AUG 25 2013
...NORTHEASTER CONDITIONS TO CONTINUE THROUGH MONDAY...
.UPDATE...STRONG HIGH PRES LOCATED OVER THE CAROLINAS AND VIRGINA
AT 1027 MB RESULTING IN STOUT NELY FLOW IN THE LOWER LEVELS. BEST
MOISTURE IS BELOW 5000 FT WITH MAINLY ISOLD TO SCATTERED SHOWERS
CONTINUING OVER NE FL ALONG A WEAKENING CONVERGENT BAND FROM SRN
ALACHUA COUNTY TO NEAR MARINELAND. MODELS ARE DISSIMILAR WITH
REGARD TO PRECIP FIELD WHICH IS NOT SURPRISING CONSIDERING THE
MESOSCALE NATURE OF THIS FEATURE. THE HRRR MODEL APPEARS TO HAVE
THE BEST HANDLE ON THE CURRENT PRECIP.
AS A INVERTED TROUGH SLOWLY INTENSIFIES ALONG THE NE FL/SE GA COAST
LATER TONIGHT WE EXPECT THAT SHOWER ACTIVITY WILL GRADUALLY FOCUS
MORE TOWARD THE COASTAL COUNTIES AND MARINE WATERS...WITH MAINLY
ISOLD TO SCATTERED COVERAGE. T-STORM PROBABILITIES ARE LOWERING
THOUGH IN-CLOUD/CLOUD TO GROUND LIGHTNING STILL APPARENT RECENTLY
IN PUTNAM/SRN ST JOHNS COUNTIES. WILL MAINTAIN SLIGHT CHANCE T-STORMS
OVER THE MARINE WATERS LATER TONIGHT AS WELL. HIGHEST POPS OF 40-60%
ARE INDICATED FOR PUTNAM ARE FLAGLER THIS EVENING. RAIN CHANCES
ARE SHOWN TO DOWN TO 20-40% AFTER MIDNIGHT WITH AGAIN BEST CHANCES
ALONG THE COASTAL COUNTIES. INLAND SE GA WILL HAVE POPS LESS THAN
20%. SOME LIGHT PATCHY FOG POSSIBLE BUT LOW LEVEL MIXING WILL
PRECLUDE ANY DENSE FOG. MINS IN THE UPPER 60S INLAND SE GA TO LOWER
TO MID 70S ELSEWHERE.
&&
.AVIATION...MOIST CONDITIONS BELOW 5000 FT AND LLVL SPEED CONVERGENCE
SUGGEST CHANCES OF MVFR CIGS THROUGH THE NIGHT AND MON MORNING.
SOUNDINGS FROM HRRR INDICATE SCT-BKN AROUND 2000 FT INTO MONDAY
MORNING. EVEN A POSSIBILITY OF IFR CIGS AT GNV AND JAX METRO
TERMINALS BUT CONFIDENCE IS NOT HIGH. ISOLD TO SCT SHOWERS ARE
EXPECTED TO DEVELOP ALONG THE COASTAL AREAS LATE TONIGHT IN
VICINITY OF TAF SITES SO INCLUDED VCSH. NELY FLOW AROUND AROUND
6-12 KT TONIGHT WILL INCREASE ON MON TO AROUND 10-15G20KT.
&&
.MARINE...BOUY AND CMAN OBS SHOW NE WINDS AROUND 20 KNOTS WITH
HIGHER GUSTS...AND 6 TO 7 FOOT SEAS. HAVE EXTENDED ADVISORY THROUGH
TONIGHT FROM SAUF1 NORTHWARD. MODELS ARE RUNNING A LITTLE TOO LOW
WITH SEAS AND WINDS AND HAVE ADJUSTED GRIDS UPWARD. EXPECT GRADUAL
DECREASE IN WINDS AND SEAS TOMORROW WITH SCEC CONDITIONS EXPECTED.
RIP CURRENTS: MODERATE RISK OF RIP CURRENTS THROUGH MONDAY DUE TO
STRONG ONSHORE WINDS AND ROUGH SURF.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 66 88 66 91 / 10 10 10 10
SSI 73 84 73 86 / 30 30 20 10
JAX 72 86 68 87 / 30 30 20 10
SGJ 73 85 73 86 / 50 30 20 20
GNV 69 87 68 90 / 30 20 20 20
OCF 70 89 69 90 / 30 20 20 20
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ALTAMAHA SOUND
GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-ALTAMAHA
SOUND GA TO FERNANDINA BEACH FL OUT 20 NM-FERNANDINA BEACH TO
ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-FERNANDINA BEACH TO ST
AUGUSTINE FL OUT 20 NM.
&&
$$
SHASHY/ZIBURA/MCALLISTER
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
355 PM EDT SAT AUG 24 2013
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN UPPER LEVEL PATTERN
ACROSS THE CONUS DOMINATED BY A LARGE AND AMPLIFIED LONG WAVE RIDGE
COVERING THE MAJORITY OF THE NATION...AND A DOWNSTREAM TROUGH
EJECTING EASTWARD FROM THE ATLANTIC COAST. OUR FORECAST AREA RESIDES
UNDER A LOCAL WEAKNESS IN THE PATTERN BETWEEN THESE TWO FEATURES. WV
IMAGERY SHOWS PLENTY OF SYNOPTIC SCALE SUBSIDENCE / DRYING ALOFT
EXPANDING SOUTHWARD INTO THE CAROLINAS/GA IN THE WAKE OF THE
DEPARTING TROUGH...HOWEVER THIS INFLUENCE WILL STAY TO THE NORTH OF
FLORIDA THE REST OF TODAY AND TONIGHT. BY SUNDAY...THERE ARE
INDICATIONS THAT SOME SUPPRESSION...AND CERTAINLY DRIER AIR ALOFT
WILL BE TRYING TO OVERSPREAD OUR NORTHERN NATURE COAST ZONES.
RADAR IS BECOMING ACTIVE THIS MID-AFTERNOON WITH THE MAJORITY OF THE
SCATTERED ACTIVITY TO THE NORTH OF TAMPA BAY. HOWEVER...THE SETUP
APPEARS VERY FAVORABLE FOR SIGNIFICANT THUNDERSTORM DEVELOPMENT
SOUTH OF I-4 ALONG THE SUNCOAST LATE AFTERNOON AND ESPECIALLY EARLY
THIS EVENING. A WELL DEFINED WEST COAST SEA-BREEZE APPEARS TO HAVE
BECOME ESTABLISHED...AND THE EAST COAST SEA-BREEZE IS RAPIDLY
CROSSING THE STATE WITHIN THE WEAK SYNOPTIC FLOW. LATEST HRRR RUNS
HAVE INITIALIZED THIS WELL AND SHOW PLENTY OF CONVECTIVE COVERAGE
ALONG THE I-75 CORRIDOR SOUTH OF TAMPA BAY BEFORE THE DAY IS OUT. A
BIT SURPRISED AT JUST HOW SLOW ACTIVITY HAS BEEN TO GET GOING SOUTH
OF TAMPA BAY...WHERE THE MOST FAVORABLE CONDITIONS APPEAR...BUT
STILL FEEL IT IS JUST A MATTER OF TIME.
&&
.SHORT TERM (THIS EVENING THROUGH MONDAY NIGHT)...
TONIGHT...SCATTERED TO NUMEROUS STORMS WILL BE AROUND WELL INTO THE
EVENING HOURS IF THE LATEST HRRR AND LOCAL WRFARW RUNS ARE "IN THE
BALLPARK" WITH THEIR FORECASTS. LATEST GRIDS SHOW THE HIGH RAIN
CHANCES FOR THE NEXT SEVERAL HOURS...AND THEN SLOWLY DIMINISH THE
THREAT LATE EVENING AND INTO THE EARLY MORNING HOURS. WITH A SURFACE
BOUNDARY SINKING SOUTH AND ABUNDANT COLUMN MOISTURE...IT SHOULD
REMAIN ACTIVE AND EVEN GET MORE ACTIVE IN TERMS OF THUNDERSTORMS
OVER THE COASTAL WATERS TONIGHT INTO SUNDAY MORNING.
SUNDAY...SOME LARGE SCALE SUBSIDENCE AND DRYING WILL CONTINUE TO
MARCH SOUTH INTO NORTHERN FLORIDA. QUITE OFTEN WE WILL SEE
CONVECTIVE DEVELOPMENT ALONG THIS PW/MOISTURE GRADIENT...AND SO
CHANCE POPS ARE PROB STILL REPRESENTATIVE...EVEN AS FAR NORTH AS
LEVY COUNTY. HOWEVER...LIKELY COVERAGE WOULD SEEM OVERDONE GIVEN THE
INCREASING NEGATIVE INFLUENCES TOWARD RISING MOTION. SOUTHERN HALF
OF THE FORECAST AREA CONTINUES TO RESIDE UNDER A FAVORABLE COLUMN TO
SUPPORT NUMEROUS AFTERNOON/EVENING STORMS.
MONDAY...A COUPLE OF FEATURES SUGGEST EVEN LOWER RAIN CHANCES
REGION-WIDE FOR MONDAY AFTERNOON/EVENING...HOWEVER GLOBAL GUIDANCE
IS NOT IN COMPLETE AGREEMENT ON THE DETAILS OF THESE FEATURES GIVING
THE FORECAST A SLIGHTLY LOWER THEN AVERAGE CONFIDENCE. SOMEWHAT
DRIER AIR WILL CONTINUE TO TRY AND WORK SOUTH INTO NORTH FLORIDA
HOLDING BACK THE OVERALL COVERAGE FOR THE NATURE COAST. FURTHER
SOUTH...THE GFS IS NOW QUITE AGGRESSIVE WITH THE FORMATION OF AN
UPPER LOW / CONVECTIVE VORT OFF THE SOUTHWEST FLORIDA COAST THAT
THEN MIGRATES WESTWARD WITH TIME. THIS VORTICITY WOULD LIKELY BE
ACCOMPANIED BY A LARGE CONVECTIVE "BLOB" OVER THE EASTERN GULF OF
MEXICO WHICH CAN HAVE THE INFLUENCE OF AIDING SUPPRESSION /
MID-LEVEL WARMING ON ITS FRIDGES. THE ECMWF DOES HINT AT THIS
FEATURE BUT IS MUCH WEAKER. WILL NOT LEAN MUCH IN EITHER DIRECTION
QUITE YET. KEEPING CHANCE POPS IN THE FORECAST...WITH HIGHEST RAIN
CHANCES STILL SOUTH OF TAMPA BAY...BUT WILL KEEP LIKELY / NUMEROUS
WORDING OUT OF THE FORECAST.
&&
.LONG TERM (TUESDAY-SATURDAY)...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT SHOWING HIGH PRESSURE
REMAINING NORTH OF THE STATE THROUGH MIDWEEK...THEN SLIPPING
SOUTHWARD THROUGH THE PENINSULA FOR THE END OF THE WEEK INTO THE
UPCOMING WEEKEND. STILL NOT SEEING ANY SIGNIFICANT WEATHER FEATURES
TO SPEAK OF THROUGH THE LONG TERM PERIODS...WITH TYPICAL SUMMERTIME
WEATHER CHARACTERIZED BY MAINLY AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS EXPECTED EACH DAY. TEMPERATURES WILL REMAIN CLOSE TO
CLIMO THROUGH THE LONG TERM PERIODS.
&&
.AVIATION...
VCNTY TSRA UNDER VFR BKN CIGS INTO THIS EVENING...WITH TEMPO MVFR
TSRA IN A 20Z-23Z WINDOW. CAN/T RULE OUT LCL IFR BUT WILL LEAVE OUT
OF TAFS FOR NOW. LIGHT VARIABLE WINDS BUT SOME SEA BREEZE INFLUENCE
TPA/PIE AND PSBL SRQ. VFR OVERNIGHT INTO SUN MORNING WITH VCNTY SHRA
TPA/PIE/LAL STARTING 15Z.
&&
.MARINE...
A STRONG RIDGE OF HIGH PRESSURE WELL TO OUR NORTH ALONG THE
MID-ATLANTIC STATES WILL PROVIDE A GENERALLY EAST TO WEST FLOW
THROUGH THE EARLY PORTION OF THE WEEK. THE GRADIENT IS EXPECTED TO
RELAX ENOUGH SUNDAY AFTERNOON TO PROVIDE FOR AN ONSHORE SEA-BREEZE
TO DEVELOP DURING THE AFTERNOON. THE RIDGE TO OUR NORTH WILL TAKE A
POSITION BY SUNDAY AND MONDAY NIGHTS TO PROVIDE SOME ENHANCED
EASTERLY FLOW EACH NIGHT INTO THE EARLY MORNING HOURS. WINDS MAY AT
TIMES APPROACH CAUTIONARY LEVELS...ESPECIALLY TO THE NORTH OF TARPON
SPRINGS.
&&
.FIRE WEATHER...
A RIDGE OF HIGH PRESSURE WILL KEEP A GENERAL EASTERLY FLOW IN PLACE
INTO THE EARLY PORTION OF THE WEEK. LOCALLY ONSHORE FLOW IS EXPECTED
FOR A TIME SUNDAY AFTERNOON NEAR THE COAST WITH SEA-BREEZE
DEVELOPMENT. A WEAK FRONT WILL DIP INTO NORTH FLORIDA AND WASH OUT
WITH TIME...BUT IS NOT EXPECTED TO PROVIDE ANY SIGNIFICANT DRYING OF
THE PATTERN TO THE LOCAL REGION. NUMEROUS AFTERNOON AND EVENING
THUNDERSTORMS LATE SATURDAY AND AGAIN ON SUNDAY WILL BECOME MORE
SCATTERED IN NATURE BY MONDAY AND TUESDAY. RELATIVE HUMIDITY VALUES
ARE FORECAST TO REMAIN WELL ABOVE CRITICAL LEVELS THROUGH
TUESDAY...AND NO SIGNIFICANT FIRE WEATHER CONCERNS ARE ANTICIPATED.
FOG POTENTIAL...PATCHY GROUND FOG IS POSSIBLE JUST BEFORE AND AROUND
SUNRISE EACH DAY...ESPECIALLY IN AREAS THAT RECEIVE LATE DAY OR
EVENING RAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 75 88 74 89 / 50 60 40 40
FMY 74 90 73 88 / 50 70 40 50
GIF 73 89 72 91 / 50 60 30 40
SRQ 75 88 74 89 / 50 60 40 40
BKV 72 89 71 90 / 50 60 40 30
SPG 77 89 77 88 / 50 60 40 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...RUDE
LONG TERM...JELSEMA
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1055 AM EDT SAT AUG 24 2013
.LATE MORNING UPDATE...
MORNING CONVECTION ALLOWING GUIDANCE MEMBERS CONTINUES TO SHOW AN
AFTERNOON EARLY EVENING PATTERN DOMINATED BY STORMS ALONG AND SOUTH
OF THE I-4 CORRIDOR...WITH MORE SCATTERED IN NATURE ACTIVITY FURTHER
NORTH ACROSS MUCH OF THE NATURE COAST. BASED ON THIS CONTINUING
TREND...HAVE REDUCED POPS BETWEEN 18-00Z FROM THE LIKELY 60%+ RANGE
DOWN TO CHANCE 40-50% TO THE NORTH OF PINELLAS/HILLSBOROUGH. THE I-4
CORRIDOR AND SOUTHWARD WILL RETAIN THE LIKELY RAIN CHANCE FORECAST
AFTER 18Z.
&&
.MID MORNING UPDATE (REST OF THE WEEKEND)...
13Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN UPPER LEVEL PATTERN
ACROSS THE CONUS DOMINATED BY A LARGE AND AMPLIFIED LONG WAVE RIDGE
COVERING THE MAJORITY OF THE NATION...AND A DOWNSTREAM TROUGH
EJECTING EASTWARD FROM THE ATLANTIC COAST. OUR FORECAST AREA RESIDES
UNDER A LOCAL WEAKNESS IN THE PATTERN BETWEEN THESE TWO FEATURES. WV
IMAGERY SHOWS PLENTY OF SYNOPTIC SCALE SUBSIDENCE / DRYING ALOFT
EXPANDING SOUTHWARD INTO THE CAROLINAS/GA IN THE WAKE OF THE
DEPARTING TROUGH...HOWEVER THIS INFLUENCE WILL STAY TO THE NORTH OF
FLORIDA TODAY. BY SUNDAY...THERE ARE INDICATIONS THAT SOME
SUPPRESSION...AND CERTAINLY DRIER AIR ALOFT WILL BE TRYING TO
OVERSPREAD OUR NORTHERN NATURE COAST ZONES.
24/12Z KTBW SOUNDING SHOWS A FAIRLY TYPICAL...ALTHOUGH SOMEWHAT
MOIST PROFILE THROUGH THE MAJORITY OF THE TROP. PW VALUES ARE A BIT
ABOVE 2"...AND THE WIND PROFILE CONFIRMS THE WEAK PATTERN ALOFT.
PROFILE SHOWS WINDS GENERALLY LESS THAN 10 KNOTS BELOW 300MB...SO
NOT A LOT OF MOTION UP THERE THIS MORNING UNTIL YOU GET TOWARD THE
VERY TOP OF THE TROP. LAPSE RATES ABOVE 500MB ARE CERTAINLY NOT ALL
THAT IMPRESSIVE...AND ALTHOUGH DON`T REALLY EXPECT THIS TO HOLD BACK
ANY CONVECTIVE COVERAGE LATER TODAY...IT MAY CERTAINLY HOLD BACK THE
POTENTIAL INTENSITY OF THE UPDRAFTS. LOCAL HI-RES CONVECTION
ALLOWING MODELS ALONG WITH THE MOST RECENT RUNS OF THE HRRR SEEM TO
BE PICKING UP ON THIS TREND AND SHOWING MAXIMUM UPDRAFTS BELOW 20
M/S...WHICH HAS BEEN FOUND TO BE GENERALLY A GOOD THRESHOLD FOR
SIGNIFICANT SEVERE POTENTIAL. THE OTHER TREND IN THE MOST RECENT
RUNS OF THESE MODELS IS THAT THEY ALL SEEM TO BE PINGING THE HIGHEST
CONVECTIVE COVERAGE THIS AFTERNOON/EARLY EVENING FROM I-4 SOUTHWARD.
IN FACT...IN MORE AND MORE OF THESE ENSEMBLE MEMBERS...IT IS
ACTUALLY A DRAMATIC INCREASE IN COVERAGE SOUTH OF I-4 COMPARED TO
ACROSS THE NATURE COAST. WILL CONTINUE TO MONITOR THE NEXT 1-2 HRRR
RUNS...AND POTENTIALLY DECREASE POPS OUT OF THE LIKELY RANGE FROM
PASCO/HERNANDO NORTHWARD. THE MOISTURE REALLY IS NOT LACKING OVER
THE NATURE COAST...SO THE EXACT REASONING FOR THIS TREND IS NOT
COMPLETELY CLEAR...AND SO RELUCTANT TO SIGNIFICANTLY REDUCE POPS FOR
THE NORTHERN ZONES JUST YET. HOWEVER...THE IMPRESSIVE AGREEMENT WITH
THE MORNING GUIDANCE RUNS IS HARD TO IGNORE.
THE ONE OTHER TREND SEEN ACROSS THE BOARD IS THE INLAND PROPAGATION
OF THE CONVECTIVE ACTIVITY TO I-75 AND EASTWARD BY EARLY EVENING
FOR THE TAMPA BAY AREA. BASED ON THIS TREND...HAVE LIKELY POPS
THROUGH 21Z...AND THEN DROP RAIN CHANCES BACK TO CHANCE INSIDE OF
I-75 FOR HILLSBOROUGH/PINELLAS/MANATEE. FURTHER SOUTH...NO
DEFINITIVE INLAND MOTION TREND IS EVIDENT AND HAVE KEPT A MORE BROAD
LIKELY RAIN CHANCE THROUGH 00Z.
SUNDAY...FEELING EVEN MORE CONFIDENT THAT POPS WILL NEED TO BE
LOWERED OUT OF THE LIKELY RANGE WITH THE NEXT FORECAST PACKAGE TO
THE NORTH OF PINELLAS/HILLSBOROUGH AS LARGE SCALE SUBSIDENCE AND
DRYING CONTINUE TO MARCH SOUTH INTO NORTHERN FLORIDA. QUITE OFTEN WE
WILL SEE CONVECTIVE DEVELOPMENT ALONG THIS PW/MOISTURE
GRADIENT...AND SO CHANCE POPS ARE PROB STILL REPRESENTATIVE...
HOWEVER LIKELY COVERAGE WOULD SEEM OVERDONE GIVEN THE INCREASING
NEGATIVE INFLUENCES TOWARD RISING MOTION. SOUTHERN HALF OF THE
FORECAST AREA CONTINUES TO RESIDE UNDER A FAVORABLE COLUMN TO
SUPPORT NUMEROUS AFTERNOON/EVENING STORMS.
&&
.AVIATION...
VFR THIS MORNING GIVES WAY TO INCREASING CLOUDS AND SCT TSRA DURING
THE AFTERNOON AND EARLY EVENING. TSRA INITIALLY FORM INLAND THEN
DRIFT BACK ACROSS THE COAST TO THE GULF...WITH MVFR/LCL IFR POSSIBLE.
&&
.MARINE...
NO HEADLINES ARE ANTICIPATED FOR THE NEXT SEVERAL DAYS. EAST TO
SOUTHEAST WINDS WILL REMAIN IN PLACE OVER THE WATERS WITH A SEA
BREEZE DEVELOPING CLOSE TO THE COAST EACH AFTERNOON.
&&
.FIRE WEATHER...
NO CONCERNS OTHER THAN POSSIBLE PATCHY GROUND FOG IN THE NORMAL
FOG-PRONE AREAS AND IN THOSE SPOTS THAT RECEIVE RAINFALL.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 89 75 88 75 / 60 30 60 30
FMY 90 75 88 73 / 60 30 70 30
GIF 91 72 91 72 / 60 50 60 20
SRQ 88 74 89 74 / 60 30 60 30
BKV 88 71 89 70 / 60 40 60 30
SPG 88 77 87 76 / 60 30 60 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATES...MROCZKA
AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS MIAMI FL
1010 AM EDT SAT AUG 24 2013
.UPDATE...
THE LATEST SATELLITE IMAGERY AND RECENT RADAR RETURNS INDICATE
WIDELY DISPERSED SHOWERS ACROSS THE REGIONAL WATERS AND ACROSS
PORTIONS OF THE SOUTH FLORIDA PENINSULA. THE 12Z SOUNDING
INDICATED A PWAT JUST UNDER TWO INCHES WITH LIGHT EAST TO SOUTHEAST
FLOW IN THE LOW TO MID LEVELS. THIS WIND PROFILE IS SOMEWHAT
FAVORABLE FOR WATERSPOUTS AND RECENT SATELLITE IMAGERY INDICATES
CLOUD CONVERGENCE BANDS ACROSS THE LOCAL ATLANTIC WATERS AND
BISCAYNE BAY AND ALSO ACROSS THE LOCAL GULF WATERS...WITH A CHANCE
OF WATERSPOUTS TODAY. OTHERWISE THE FORECAST IS ON TRACK WITH
INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS ACROSS THE
PENINSULA BY LATE MORNING WITH MORE NUMEROUS ACTIVITY ACROSS THE
INTERIOR AND WEST AS THE AFTERNOON PROGRESSES. GIVEN THE
AFOREMENTIONED WIND PROFILE THE STORM MOTION WILL BE SLOW TODAY
AND WITH LOCALLY HEAVY RAINFALL POSSIBLE THERE COULD BE ISOLATED
AREAS OF MINOR URBAN TYPE FLOODING MAINLY EXPECTED ACROSS THE
INTERIOR AND WEST THIS AFTERNOON.
60
&&
.PREV DISCUSSION... /ISSUED 827 AM EDT SAT AUG 24 2013/
AVIATION...
THE TAIL END OF AN UPPER LEVEL TROUGH AXIS WILL SLIDE SOUTH INTO
NORTHERN FLORIDA TODAY...AND TOWARDS LAKE OKEECHOBEE BY THE END OF
THE PERIOD. UPPER LEVEL CLOUDS WILL INCREASE TOWARDS 12Z ON SUNDAY
AS THE SOUTHERN END OF THE TROUGH AXIS APPROACHES. THE PRESSURE
GRADIENT IS SLIGHTLY WEAKER...WITH EASTERLY WINDS EXPECTED TO
INCREASE TO AROUND 10 KNOTS FOR THE EAST COAST TAF SITES. KEPT VCSH
FOR THE EAST COAST TAF SITES TODAY. THE THUNDERSTORM THREAT IS
FORECAST TO BE MAINLY OVER THE INTERIOR AND GULF COAST. AT KAPF...A
SEA BREEZE IS FORECAST TO PUSH INLAND BETWEEN 17-18Z. NUMEROUS
SHOWERS AND STORMS ARE FORECAST TO DEVELOP IN THE AFTERNOON...SO
ADDED A TEMPO GROUP FROM 19-23Z. MVFR/IFR CONDITIONS ARE POSSIBLE IN
STORMS. LIGHT WINDS ARE EXPECTED AGAIN OVERNIGHT TONIGHT.
PREV DISCUSSION... /ISSUED 418 AM EDT SAT AUG 24 2013/
SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL IMPACT SOUTH FLORIDA MAINLY FROM
TONIGHT THROUGH EARLY IN THE WEEK...LEADING TO A GRADUAL INCREASE IN
RAIN CHANCES THROUGH THE PERIOD. HIGH PRESSURE BUILDS BACK INTO THE
REGION EARLY TO MIDDLE PART OF THE NEXT WEEK.
SHORT TERM /TODAY THROUGH SUNDAY NIGHT/...
SYNOPTIC PATTERN THIS WEEKEND WILL BE DOMINATED BY H5 TROUGH OVER EASTERN
UNITED STATES WITH ITS AXIS AND ASSOCIATED SHORT WAVE...THOUGH DIFFUSE
BUT SHOWN IN VARYING DEGREES BY BOTH GLOBAL AND MESOSCALE MODELS...REACHING
VICINITY OF SOUTH FLORIDA PARTICULARLY BY SUNDAY WITH ITS INFLUENCE
ACROSS THE AREA INCREASING BEGINNING TODAY. ALONG WITH THIS FEATURE...A
LOW-LEVEL BOUNDARY/DECAYING COLD FRONT WILL SPREAD INTO CENTRAL FLORIDA
TODAY AND COULD REACH SOUTH FLORIDA SUNDAY ALTHOUGH IT IS MOST LIKELY
TO WASH OUT BEFORE THEN BUT ITS LINGERING LEFT OVER WILL HELP ENHANCE
CHANCES OF RAIN. WINDS COULD TURN NORTHEASTERLY SUNDAY WITH THIS SOLUTION...AS
NAM AS WELL AS GFS SUGGEST THE BOUNDARY WILL EITHER PASS THROUGH MOST
OF THE CWA SOMETIME BETWEEN LATE SUNDAY AND MONDAY OR SIMPLY THE WIND
WILL SHIFT FROM THE NORTHEAST AS HIGH BUILDS NORTH OF THE AREA BEHIND
DIFFUSING BOUNDARY.
FOR TODAY...HIGH RESOLUTION LOCAL MODELS ALONG WITH HRRR INDICATE PATTERN
OF LATE MORNING AND EARLY AFTERNOON EAST COAST SHOWERS AND STORMS TRANSITIONING
TO INTERIOR AND WEST COAST AGAIN DURING THE AFTERNOON AND EVENING. STORM
MOTION VECTOR FAVORS INTERIOR AND WEST COAST BUT IS WEAK ENOUGH THAT
SOME ACTIVITY MIGHT LINGER ACROSS EAST COAST ALSO INTO THE AFTERNOON
AND EVENING. FOR SUNDAY CONVERGENCE IN THE VICINITY OF THE AFOREMENTIONED
SURFACE BOUNDARY COULD ENHANCE SHOWERS AND THUNDERSTORMS...BUT EVEN
IF BOUNDARY REMAINS NORTH OF CWA...SCATTERED TO NUMEROUS SHOWERS AND
STORMS CAN BE EXPECTED WITH STORM MOTION VECTORS SUGGESTING ABOUT EQUAL
CHANCES EVERYWHERE. WE ARE BASICALLY TALKING ABOUT AN ENHANCED DIURNAL
CYCLE WITH LINGERING ACTIVITY POSSIBLY EXTENDING INTO SUNDAY NIGHT IN
THE PRESENCE OF UPPER LEVEL S/W.
TEMPERATURES WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL...PARTICULARLY
DURING THE OVERNIGHTS.
ONSHORE FLOW WILL CONTINUE THROUGH THE WEEKEND ALBEIT WEAKER...PROLONGING
A SLIGHT RISK OF RIP CURRENTS ON ATLANTIC BEACHES. HOWEVER...THIS
THREAT SHOULD BE GRADUALLY DIMINISHING INTO THE WEEKEND.
LONG TERM /MONDAY THROUGH FRIDAY/...
THE PREVIOUS DISCUSSED SURFACE BOUNDARY AND UPPER S/W WILL FURTHER
WEAKEN THROUGH THE FIRST HALF OF THE UPCOMING WEEK BUT NOT WITHOUT
RESULTING IN SCATTERED TO NUMEROUS SHOWERS AND STORMS AGAIN ON MONDAY.
HOWEVER BY THE MIDDLE TO LATTER PART OF THE WEEK AN UPPER LEVEL
TROUGH OFF THE EAST COAST OF THE US WILL RETROGRADE IN
ASSOCIATION WITH HIGH AMPLITUDE WAVE PATTERN. GFS IS MORE
AGGRESSIVE WITH THIS THAN ECMWF BUT THE BOTTOM LINE IS THE AREA
WILL BE BETWEEN A STRONG HIGH PRESSURE RIDGE ACROSS THE MIDDLE OF
THE COUNTRY AND THE TROUGH OF LOW PRESSURE OFF THE EAST COAST OF THE
US. THIS IS ALSO CONSISTENT WITH THE ENSEMBLE FORECASTS. AT LOW
LEVELS AREA WILL BE UNDER THE INFLUENCE OF WEAK RIDGE OF HIGH
PRESSURE JUST TO THE NORTH POSSIBLY PUSHING SOUTH ACROSS THE AREA
BY LATE IN THE WEEK. ALONG WITH THIS MOISTURE LEVELS WILL BE
RUNNING ABOVE NORMAL EARLY IN THE WEEK, AROUND NORMAL MIDDLE TO
LATTER PART OF THE WEEK AND PERHAPS SLIGHTLY ABOVE NORMAL BY LATE IN
THE WEEK.
BOTTOM LINE...AFTER THE START OF THE WEEK ON MONDAY AREA WILL BE
UNDER A WEAK STEERING FLOW ENVIRONMENT WITH ABOUT EQUAL CHANCES
OF SCATTERED SHOWERS AND THUNDERSTORMS EVERYWHERE THROUGH THE PERIOD
ALONG WITH TYPICAL DIURNAL CYCLE AND TEMPERATURES NEAR NORMAL.
MARINE...
OUTSIDE A BRIEF PERIOD OF WINDS OF AROUND 15 KNOTS OFFSHORE THE
SOUTHWEST FLORIDA COAST SUNDAY...WINDS AND WAVES WILL REMAIN BELOW
10 TO 15 KNOTS AND 2 TO 4 FEET RESPECTIVELY THROUGH THE FORECAST
PERIOD SO NO HIGHLIGHTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 78 87 76 / 50 30 50 30
FORT LAUDERDALE 89 80 87 77 / 40 20 50 30
MIAMI 90 78 88 77 / 40 20 50 30
NAPLES 91 75 88 74 / 60 40 60 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...60/BD
AVIATION/RADAR...23/SK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
905 AM EDT SAT AUG 24 2013
.UPDATE (REST OF THE WEEKEND)...
13Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN UPPER LEVEL PATTERN
ACROSS THE CONUS DOMINATED BY A LARGE AND AMPLIFIED LONG WAVE RIDGE
COVERING THE MAJORITY OF THE NATION...AND A DOWNSTREAM TROUGH
EJECTING EASTWARD FROM THE ATLANTIC COAST. OUR FORECAST AREA RESIDES
UNDER A LOCAL WEAKNESS IN THE PATTERN BETWEEN THESE TWO FEATURES. WV
IMAGERY SHOWS PLENTY OF SYNOPTIC SCALE SUBSIDENCE / DRYING ALOFT
EXPANDING SOUTHWARD INTO THE CAROLINAS/GA IN THE WAKE OF THE
DEPARTING TROUGH...HOWEVER THIS INFLUENCE WILL STAY TO THE NORTH OF
FLORIDA TODAY. BY SUNDAY...THERE ARE INDICATIONS THAT SOME
SUPPRESSION...AND CERTAINLY DRIER AIR ALOFT WILL BE TRYING TO
OVERSPREAD OUR NORTHERN NATURE COAST ZONES.
24/12Z KTBW SOUNDING SHOWS A FAIRLY TYPICAL...ALTHOUGH SOMEWHAT
MOIST PROFILE THROUGH THE MAJORITY OF THE TROP. PW VALUES ARE A BIT
ABOVE 2"...AND THE WIND PROFILE CONFIRMS THE WEAK PATTERN ALOFT.
PROFILE SHOWS WINDS GENERALLY LESS THAN 10 KNOTS BELOW 300MB...SO
NOT A LOT OF MOTION UP THERE THIS MORNING UNTIL YOU GET TOWARD THE
VERY TOP OF THE TROP. LAPSE RATES ABOVE 500MB ARE CERTAINLY NOT ALL
THAT IMPRESSIVE...AND ALTHOUGH DON`T REALLY EXPECT THIS TO HOLD BACK
ANY CONVECTIVE COVERAGE LATER TODAY...IT MAY CERTAINLY HOLD BACK THE
POTENTIAL INTENSITY OF THE UPDRAFTS. LOCAL HI-RES CONVECTION
ALLOWING MODELS ALONG WITH THE MOST RECENT RUNS OF THE HRRR SEEM TO
BE PICKING UP ON THIS TREND AND SHOWING MAXIMUM UPDRAFTS BELOW 20
M/S...WHICH HAS BEEN FOUND TO BE GENERALLY A GOOD THRESHOLD FOR
SIGNIFICANT SEVERE POTENTIAL. THE OTHER TREND IN THE MOST RECENT
RUNS OF THESE MODELS IS THAT THEY ALL SEEM TO BE PINGING THE HIGHEST
CONVECTIVE COVERAGE THIS AFTERNOON/EARLY EVENING FROM I-4 SOUTHWARD.
IN FACT...IN MORE AND MORE OF THESE ENSEMBLE MEMBERS...IT IS
ACTUALLY A DRAMATIC INCREASE IN COVERAGE SOUTH OF I-4 COMPARED TO
ACROSS THE NATURE COAST. WILL CONTINUE TO MONITOR THE NEXT 1-2 HRRR
RUNS...AND POTENTIALLY DECREASE POPS OUT OF THE LIKELY RANGE FROM
PASCO/HERNANDO NORTHWARD. THE MOISTURE REALLY IS NOT LACKING OVER
THE NATURE COAST...SO THE EXACT REASONING FOR THIS TREND IS NOT
COMPLETELY CLEAR...AND SO RELUCTANT TO SIGNIFICANTLY REDUCE POPS FOR
THE NORTHERN ZONES JUST YET. HOWEVER...THE IMPRESSIVE AGREEMENT WITH
THE MORNING GUIDANCE RUNS IS HARD TO IGNORE.
THE ONE OTHER TREND SEEN ACROSS THE BOARD IS THE INLAND PROPAGATION
OF THE CONVECTIVE ACTIVITY TO I-75 AND EASTWARD BY EARLY EVENING
FOR THE TAMPA BAY AREA. BASED ON THIS TREND...HAVE LIKELY POPS
THROUGH 21Z...AND THEN DROP RAIN CHANCES BACK TO CHANCE INSIDE OF
I-75 FOR HILLSBOROUGH/PINELLAS/MANATEE. FURTHER SOUTH...NO
DEFINITIVE INLAND MOTION TREND IS EVIDENT AND HAVE KEPT A MORE BROAD
LIKELY RAIN CHANCE THROUGH 00Z.
SUNDAY...FEELING EVEN MORE CONFIDENT THAT POPS WILL NEED TO BE
LOWERED OUT OF THE LIKELY RANGE WITH THE NEXT FORECAST PACKAGE TO
THE NORTH OF PINELLAS/HILLSBOROUGH AS LARGE SCALE SUBSIDENCE AND
DRYING CONTINUE TO MARCH SOUTH INTO NORTHERN FLORIDA. QUITE OFTEN WE
WILL SEE CONVECTIVE DEVELOPMENT ALONG THIS PW/MOISTURE
GRADIENT...AND SO CHANCE POPS ARE PROB STILL REPRESENTATIVE...
HOWEVER LIKELY COVERAGE WOULD SEEM OVERDONE GIVEN THE INCREASING
NEGATIVE INFLUENCES TOWARD RISING MOTION. SOUTHERN HALF OF THE
FORECAST AREA CONTINUES TO RESIDE UNDER A FAVORABLE COLUMN TO
SUPPORT NUMEROUS AFTERNOON/EVENING STORMS.
&&
.AVIATION...
VFR THIS MORNING GIVES WAY TO INCREASING CLOUDS AND SCT TSRA DURING
THE AFTERNOON AND EARLY EVENING. TSRA INITIALLY FORM INLAND THEN
DRIFT BACK ACROSS THE COAST TO THE GULF...WITH MVFR/LCL IFR POSSIBLE.
&&
.MARINE...
NO HEADLINES ARE ANTICIPATED FOR THE NEXT SEVERAL DAYS. EAST TO
SOUTHEAST WINDS WILL REMAIN IN PLACE OVER THE WATERS WITH A SEA
BREEZE DEVELOPING CLOSE TO THE COAST EACH AFTERNOON.
&&
.FIRE WEATHER...
NO CONCERNS OTHER THAN POSSIBLE PATCHY GROUND FOG IN THE NORMAL
FOG-PRONE AREAS AND IN THOSE SPOTS THAT RECEIVE RAINFALL.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 89 75 88 75 / 60 30 60 30
FMY 90 75 88 73 / 60 30 70 30
GIF 91 72 91 72 / 60 50 60 20
SRQ 88 74 89 74 / 60 30 60 30
BKV 88 71 89 70 / 60 40 60 30
SPG 88 77 87 76 / 60 30 60 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS MIAMI FL
827 AM EDT SAT AUG 24 2013
.AVIATION...
THE TAIL END OF AN UPPER LEVEL TROUGH AXIS WILL SLIDE SOUTH INTO
NORTHERN FLORIDA TODAY...AND TOWARDS LAKE OKEECHOBEE BY THE END OF
THE PERIOD. UPPER LEVEL CLOUDS WILL INCREASE TOWARDS 12Z ON SUNDAY
AS THE SOUTHERN END OF THE TROUGH AXIS APPROACHES. THE PRESSURE
GRADIENT IS SLIGHTLY WEAKER...WITH EASTERLY WINDS EXPECTED TO
INCREASE TO AROUND 10 KNOTS FOR THE EAST COAST TAF SITES. KEPT VCSH
FOR THE EAST COAST TAF SITES TODAY. THE THUNDERSTORM THREAT IS
FORECAST TO BE MAINLY OVER THE INTERIOR AND GULF COAST. AT KAPF...A
SEA BREEZE IS FORECAST TO PUSH INLAND BETWEEN 17-18Z. NUMEROUS
SHOWERS AND STORMS ARE FORECAST TO DEVELOP IN THE AFTERNOON...SO
ADDED A TEMPO GROUP FROM 19-23Z. MVFR/IFR CONDITIONS ARE POSSIBLE IN
STORMS. LIGHT WINDS ARE EXPECTED AGAIN OVERNIGHT TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 418 AM EDT SAT AUG 24 2013/
SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL IMPACT SOUTH FLORIDA MAINLY FROM
TONIGHT THROUGH EARLY IN THE WEEK...LEADING TO A GRADUAL INCREASE IN
RAIN CHANCES THROUGH THE PERIOD. HIGH PRESSURE BUILDS BACK INTO THE
REGION EARLY TO MIDDLE PART OF THE NEXT WEEK.
SHORT TERM /TODAY THROUGH SUNDAY NIGHT/...
SYNOPTIC PATTERN THIS WEEKEND WILL BE DOMINATED BY H5 TROUGH OVER EASTERN
UNITED STATES WITH ITS AXIS AND ASSOCIATED SHORT WAVE...THOUGH DIFFUSE
BUT SHOWN IN VARYING DEGREES BY BOTH GLOBAL AND MESOSCALE MODELS...REACHING
VICINITY OF SOUTH FLORIDA PARTICULARLY BY SUNDAY WITH ITS INFLUENCE
ACROSS THE AREA INCREASING BEGINNING TODAY. ALONG WITH THIS FEATURE...A
LOW-LEVEL BOUNDARY/DECAYING COLD FRONT WILL SPREAD INTO CENTRAL FLORIDA
TODAY AND COULD REACH SOUTH FLORIDA SUNDAY ALTHOUGH IT IS MOST LIKELY
TO WASH OUT BEFORE THEN BUT ITS LINGERING LEFT OVER WILL HELP ENHANCE
CHANCES OF RAIN. WINDS COULD TURN NORTHEASTERLY SUNDAY WITH THIS SOLUTION...AS
NAM AS WELL AS GFS SUGGEST THE BOUNDARY WILL EITHER PASS THROUGH MOST
OF THE CWA SOMETIME BETWEEN LATE SUNDAY AND MONDAY OR SIMPLY THE WIND
WILL SHIFT FROM THE NORTHEAST AS HIGH BUILDS NORTH OF THE AREA BEHIND
DIFFUSING BOUNDARY.
FOR TODAY...HIGH RESOLUTION LOCAL MODELS ALONG WITH HRRR INDICATE PATTERN
OF LATE MORNING AND EARLY AFTERNOON EAST COAST SHOWERS AND STORMS TRANSITIONING
TO INTERIOR AND WEST COAST AGAIN DURING THE AFTERNOON AND EVENING. STORM
MOTION VECTOR FAVORS INTERIOR AND WEST COAST BUT IS WEAK ENOUGH THAT
SOME ACTIVITY MIGHT LINGER ACROSS EAST COAST ALSO INTO THE AFTERNOON
AND EVENING. FOR SUNDAY CONVERGENCE IN THE VICINITY OF THE AFOREMENTIONED
SURFACE BOUNDARY COULD ENHANCE SHOWERS AND THUNDERSTORMS...BUT EVEN
IF BOUNDARY REMAINS NORTH OF CWA...SCATTERED TO NUMEROUS SHOWERS AND
STORMS CAN BE EXPECTED WITH STORM MOTION VECTORS SUGGESTING ABOUT EQUAL
CHANCES EVERYWHERE. WE ARE BASICALLY TALKING ABOUT AN ENHANCED DIURNAL
CYCLE WITH LINGERING ACTIVITY POSSIBLY EXTENDING INTO SUNDAY NIGHT IN
THE PRESENCE OF UPPER LEVEL S/W.
TEMPERATURES WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL...PARTICULARLY
DURING THE OVERNIGHTS.
ONSHORE FLOW WILL CONTINUE THROUGH THE WEEKEND ALBEIT WEAKER...PROLONGING
A SLIGHT RISK OF RIP CURRENTS ON ATLANTIC BEACHES. HOWEVER...THIS
THREAT SHOULD BE GRADUALLY DIMINISHING INTO THE WEEKEND.
LONG TERM /MONDAY THROUGH FRIDAY/...
THE PREVIOUS DISCUSSED SURFACE BOUNDARY AND UPPER S/W WILL FURTHER
WEAKEN THROUGH THE FIRST HALF OF THE UPCOMING WEEK BUT NOT WITHOUT
RESULTING IN SCATTERED TO NUMEROUS SHOWERS AND STORMS AGAIN ON MONDAY.
HOWEVER BY THE MIDDLE TO LATTER PART OF THE WEEK AN UPPER LEVEL
TROUGH OFF THE EAST COAST OF THE US WILL RETROGRADE IN
ASSOCIATION WITH HIGH AMPLITUDE WAVE PATTERN. GFS IS MORE
AGGRESSIVE WITH THIS THAN ECMWF BUT THE BOTTOM LINE IS THE AREA
WILL BE BETWEEN A STRONG HIGH PRESSURE RIDGE ACROSS THE MIDDLE OF
THE COUNTRY AND THE TROUGH OF LOW PRESSURE OFF THE EAST COAST OF THE
US. THIS IS ALSO CONSISTENT WITH THE ENSEMBLE FORECASTS. AT LOW
LEVELS AREA WILL BE UNDER THE INFLUENCE OF WEAK RIDGE OF HIGH
PRESSURE JUST TO THE NORTH POSSIBLY PUSHING SOUTH ACROSS THE AREA
BY LATE IN THE WEEK. ALONG WITH THIS MOISTURE LEVELS WILL BE
RUNNING ABOVE NORMAL EARLY IN THE WEEK, AROUND NORMAL MIDDLE TO
LATTER PART OF THE WEEK AND PERHAPS SLIGHTLY ABOVE NORMAL BY LATE IN
THE WEEK.
BOTTOM LINE...AFTER THE START OF THE WEEK ON MONDAY AREA WILL BE
UNDER A WEAK STEERING FLOW ENVIRONMENT WITH ABOUT EQUAL CHANCES
OF SCATTERED SHOWERS AND THUNDERSTORMS EVERYWHERE THROUGH THE PERIOD
ALONG WITH TYPICAL DIURNAL CYCLE AND TEMPERATURES NEAR NORMAL.
MARINE...
OUTSIDE A BRIEF PERIOD OF WINDS OF AROUND 15 KNOTS OFFSHORE THE
SOUTHWEST FLORIDA COAST SUNDAY...WINDS AND WAVES WILL REMAIN BELOW
10 TO 15 KNOTS AND 2 TO 4 FEET RESPECTIVELY THROUGH THE FORECAST
PERIOD SO NO HIGHLIGHTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 78 87 76 / 50 30 50 30
FORT LAUDERDALE 89 80 87 77 / 40 20 50 30
MIAMI 90 78 88 77 / 40 20 50 30
NAPLES 91 75 88 74 / 60 40 60 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...60/BD
AVIATION/RADAR...23/SK
AREA FORECAST DISCUSSION
NWS MIAMI FL
418 AM EDT SAT AUG 24 2013
.SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL IMPACT SOUTH FLORIDA MAINLY FROM
TONIGHT THROUGH EARLY IN THE WEEK...LEADING TO A GRADUAL INCREASE IN
RAIN CHANCES THROUGH THE PERIOD. HIGH PRESSURE BUILDS BACK INTO THE
REGION EARLY TO MIDDLE PART OF THE NEXT WEEK.
&&
.SHORT TERM /TODAY THROUGH SUNDAY NIGHT/...
SYNOPTIC PATTERN THIS WEEKEND WILL BE DOMINATED BY H5 TROUGH OVER EASTERN
UNITED STATES WITH ITS AXIS AND ASSOCIATED SHORT WAVE...THOUGH DIFFUSE
BUT SHOWN IN VARYING DEGREES BY BOTH GLOBAL AND MESOSCALE MODELS...REACHING
VICINITY OF SOUTH FLORIDA PARTICULARLY BY SUNDAY WITH ITS INFLUENCE
ACROSS THE AREA INCREASING BEGINNING TODAY. ALONG WITH THIS FEATURE...A
LOW-LEVEL BOUNDARY/DECAYING COLD FRONT WILL SPREAD INTO CENTRAL FLORIDA
TODAY AND COULD REACH SOUTH FLORIDA SUNDAY ALTHOUGH IT IS MOST LIKELY
TO WASH OUT BEFORE THEN BUT ITS LINGERING LEFT OVER WILL HELP ENHANCE
CHANCES OF RAIN. WINDS COULD TURN NORTHEASTERLY SUNDAY WITH THIS SOLUTION...AS
NAM AS WELL AS GFS SUGGEST THE BOUNDARY WILL EITHER PASS THROUGH MOST
OF THE CWA SOMETIME BETWEEN LATE SUNDAY AND MONDAY OR SIMPLY THE WIND
WILL SHIFT FROM THE NORTHEAST AS HIGH BUILDS NORTH OF THE AREA BEHIND
DIFFUSING BOUNDARY.
FOR TODAY...HIGH RESOLUTION LOCAL MODELS ALONG WITH HRRR INDICATE PATTERN
OF LATE MORNING AND EARLY AFTERNOON EAST COAST SHOWERS AND STORMS TRANSITIONING
TO INTERIOR AND WEST COAST AGAIN DURING THE AFTERNOON AND EVENING. STORM
MOTION VECTOR FAVORS INTERIOR AND WEST COAST BUT IS WEAK ENOUGH THAT
SOME ACTIVITY MIGHT LINGER ACROSS EAST COAST ALSO INTO THE AFTERNOON
AND EVENING. FOR SUNDAY CONVERGENCE IN THE VICINITY OF THE AFOREMENTIONED
SURFACE BOUNDARY COULD ENHANCE SHOWERS AND THUNDERSTORMS...BUT EVEN
IF BOUNDARY REMAINS NORTH OF CWA...SCATTERED TO NUMEROUS SHOWERS AND
STORMS CAN BE EXPECTED WITH STORM MOTION VECTORS SUGGESTING ABOUT EQUAL
CHANCES EVERYWHERE. WE ARE BASICALLY TALKING ABOUT AN ENHANCED DIURNAL
CYCLE WITH LINGERING ACTIVITY POSSIBLY EXTENDING INTO SUNDAY NIGHT IN
THE PRESENCE OF UPPER LEVEL S/W.
TEMPERATURES WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL...PARTICULARLY
DURING THE OVERNIGHTS.
ONSHORE FLOW WILL CONTINUE THROUGH THE WEEKEND ALBEIT WEAKER...PROLONGING
A SLIGHT RISK OF RIP CURRENTS ON ATLANTIC BEACHES. HOWEVER...THIS
THREAT SHOULD BE GRADUALLY DIMINISHING INTO THE WEEKEND.
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE PREVIOUS DISCUSSED SURFACE BOUNDARY AND UPPER S/W WILL FURTHER
WEAKEN THROUGH THE FIRST HALF OF THE UPCOMING WEEK BUT NOT WITHOUT
RESULTING IN SCATTERED TO NUMEROUS SHOWERS AND STORMS AGAIN ON MONDAY.
HOWEVER BY THE MIDDLE TO LATTER PART OF THE WEEK AN UPPER LEVEL
TROUGH OFF THE EAST COAST OF THE US WILL RETROGRADE IN
ASSOCIATION WITH HIGH AMPLITUDE WAVE PATTERN. GFS IS MORE
AGGRESSIVE WITH THIS THAN ECMWF BUT THE BOTTOM LINE IS THE AREA
WILL BE BETWEEN A STRONG HIGH PRESSURE RIDGE ACROSS THE MIDDLE OF
THE COUNTRY AND THE TROUGH OF LOW PRESSURE OFF THE EAST COAST OF THE
US. THIS IS ALSO CONSISTENT WITH THE ENSEMBLE FORECASTS. AT LOW
LEVELS AREA WILL BE UNDER THE INFLUENCE OF WEAK RIDGE OF HIGH
PRESSURE JUST TO THE NORTH POSSIBLY PUSHING SOUTH ACROSS THE AREA
BY LATE IN THE WEEK. ALONG WITH THIS MOISTURE LEVELS WILL BE
RUNNING ABOVE NORMAL EARLY IN THE WEEK, AROUND NORMAL MIDDLE TO
LATTER PART OF THE WEEK AND PERHAPS SLIGHTLY ABOVE NORMAL BY LATE IN
THE WEEK.
BOTTOM LINE...AFTER THE START OF THE WEEK ON MONDAY AREA WILL BE
UNDER A WEAK STEERING FLOW ENVIRONMENT WITH ABOUT EQUAL CHANCES
OF SCATTERED SHOWERS AND THUNDERSTORMS EVERYWHERE THROUGH THE PERIOD
ALONG WITH TYPICAL DIURNAL CYCLE AND TEMPERATURES NEAR NORMAL.
&&
.MARINE...
OUTSIDE A BRIEF PERIOD OF WINDS OF AROUND 15 KNOTS OFFSHORE THE
SOUTHWEST FLORIDA COAST SUNDAY...WINDS AND WAVES WILL REMAIN BELOW
10 TO 15 KNOTS AND 2 TO 4 FEET RESPECTIVELY THROUGH THE FORECAST
PERIOD SO NO HIGHLIGHTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 78 87 76 / 50 30 50 30
FORT LAUDERDALE 89 80 87 77 / 40 20 50 30
MIAMI 90 78 88 77 / 40 20 50 30
NAPLES 91 75 88 74 / 60 40 60 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
406 AM EDT SAT AUG 24 2013
.SYNOPSIS...
A COLD FRONT WILL SLOWLY PUSH SOUTH THROUGH THE AREA TODAY AND
BE FOLLOWED BY COOLER AND DRIER CONDITIONS THROUGH EARLY NEXT
WEEK. ANOTHER WEAK COLD FRONT COULD APPROACH FROM THE NORTH LATE
NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
THROUGH SUNRISE...24/06Z SURFACE ANALYSIS PLACED THE COLD ACROSS
THE CENTRAL MIDLANDS INTO THE PEE DEE REGION OF NORTHEAST SOUTH
CAROLINA. THE FRONT IS MOVING SLOWLY SOUTH IN RESPONSE TO PHASED
SHORTWAVE ENERGY PASSING OFF THE MID-ATLANTIC COAST. SCATTERED
SHOWERS/TSTMS ARE SLOWLY DEVELOPING FROM NEAR COLUMBIA EAST TO
NORTH MYRTLE BEACH. THIS ACTIVITY IS DEVELOPING WITHIN A TONGUE OF
ENHANCED INSTABILITY AND LOW-LEVEL CONVERGENCE EXTENDING FROM THE
EASTERN MIDLANDS INTO THE CHARLESTON TRI-COUNTY AREA. THE LATEST
RUNS OF THE H3R AND RAP WITH SUPPORT FROM THE LATEST 4KM NSSL WRF
SHOW CONVECTION MEANDERING SOUTHEAST OVER THE NEXT SEVERAL
HOURS...PASSING NEAR OR JUST TO THE EAST OF THE CHARLESTON METRO
AREA. WILL SHOW THE HIGHEST POPS--UP TO 40 PERCENT--IN THIS AREA
THROUGH SUNRISE WITH SLIGHT CHANCE POPS EXTENDING AS FAR SOUTH AS
THE SAVANNAH RIVER. LOWS IN THE LOWER 70S INLAND TO UPPER 70S AT
THE BEACHES LOOK ON TRACK.
TODAY...THE BACKDOOR COLD FRONT WILL MEANDER SLOWLY SOUTH ACROSS
SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA AS SHORTWAVE ENERGY
PROPAGATES FARTHER OFFSHORE. HIGH PRESSURE IS FORECAST TO
GRADUALLY WEDGE INTO THE REGION FROM THE NORTHEAST BEHIND THE
FRONT...BUT THIS WILL BE A VERY SLOW PROCESS. IN FACT...THE FRONT
DOES NOT LOOK TO CLEAR THE SAVANNAH METRO AREA UNTIL LATE THIS
AFTERNOON AND THE ALTAMAHA RIVER THIS EVENING AS IT BECOME
INTERMINGLED WITHIN THE SEA BREEZE CIRCULATION. ALOFT...HEIGHTS
WILL SLOWLY INCREASE IN RESPONSE TO A VERY LARGE...VERTICALLY
STACKED ANTICYCLONE CENTERED OVER THE CENTRAL PLAINS BUILDING EAST.
AS THE FRONT DRAGS SOUTH AND SUBSIDENCE/DRY AIR BEGINS TO ADVECT
IN ALOFT...THE PROSPECT FOR WIDESPREAD CONVECTIVE RAINS LOOKS
SLIM. EXPECT ONLY ISOLATED TO SCATTERED SHOWERS/TSTMS AT BEST WITH
THE GREATEST COVERAGE OCCURRING ALONG AND SOUTH OF THE COLD FRONT.
FARTHER NORTH...RAIN CHANCES LOOK TO END BY LATE MORNING AS
DEWPOINTS FALL SLIGHTLY. WILL UTILIZE A 20/40 POP REGIME FOR TODAY
WITH THE HIGHEST GRIDDED POPS CLUSTERED DOWN ALONG THE ALTAMAHA
RIVER WHERE THE ALIGNMENT OF MOISTURE...LIFT AND INSTABILITY WILL
BE THE MOST IDEAL. HIGH WILL RANGE FROM THE MID 80S ACROSS THE
CHARLESTON TRI-COUNTY AREA TO THE UPPER 80S/NEAR 90 ELSEWHERE.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
TONIGHT...THE COLD FRONT WILL GRADUALLY CLEAR THE ALTAMAHA RIVER
AS A WEDGE OF HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. RAIN
CHANCES WILL DIMINISH WITH TIME...HOWEVER THERE WILL BE ENOUGH OF
A MOIST...ONSHORE FLOW TO SUPPORT AT LEAST ISOLATED SHOWERS/TSTMS
ACROSS THE GEORGIA COASTAL COUNTIES THROUGH SUNRISE SUNDAY.
CLEARING WILL ALSO ENSUE FROM NORTH TO SOUTH...ALTHOUGH MOSTLY
CLOUDY SKIES WILL LIKELY LINGER ALONG NORTH COASTAL GEORGIA FOR A
GOOD PORTION OF THE NIGHT. LOWS WILL RANGE FROM THE MID 60S ACROSS
NORTHERN PORTIONS OF BERKELEY/DORCHESTER COUNTIES TO THE MID 70S
ALONG COASTAL GEORGIA. WINDS WILL BECOME BREEZY AT TIMES ALONG THE
BEACHES AS THE GRADIENT PINCHES IN RESPONSE TO HIGH PRESSURE
WEDGING INTO THE REGION. THIS WILL BE ESPECIALLY TRUE ALONG THE
BEACHES OF CHARLESTON COUNTY WHERE WINDS COULD BE 15-25 MPH WITH
GUSTS TO 30 MPH FOR MUCH OF THE OVERNIGHT HOURS.
SUNDAY...SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD FROM THE
NORTH. SOLID NORTHEAST FLOW WILL ADVECT A COOLER AND DRIER AIR
MASS INTO THE REGION...WITH TEMPERATURES ONLY REACHING THE MID
80S...AND AFTERNOON DEWPOINTS FALLING INTO THE LOW 60S NORTH TO
AROUND 70 SOUTH. HAVE CONFINED ANY SLIGHT TO LOW THUNDERSTORM
CHANCES MAINLY SOUTH OF THE SAVANNAH RIVER...CLOSEST TO LINGERING
MOISTURE AND CONVERGENCE WITHIN THE VICINITY OF THE FRONTAL ZONE.
EXPECT ALL LAND ZONES TO BE RAIN FREE BY THE EVENING HOURS...AS
FRONTAL FORCING CONTINUES TO SHIFT FARTHER AWAY FROM THE FORECAST
AREA. LOW TEMPERATURES WILL FALL NEARLY 10 DEGREES BELOW
AVERAGE...REACHING THE LOW TO MID 60S INLAND.
MONDAY...A FAIRLY UNSEASONAL PATTERN WILL PERSIST...SUPPORTING
RELATIVELY COOL AND DRY CONDITIONS FOR LATE AUGUST. THE CENTER OF
SURFACE HIGH PRESSURE WILL SLIP DIRECTLY OVER THE FORECAST AREA BY
MONDAY...WHILE STRONG UPPER RIDGING ENCOMPASSES MUCH OF THE
CENTRAL UNITED STATES. AFTERNOON DEWPOINTS IN THE LOW TO MID 60S
ARE EVIDENCE OF THE DRY AIR LINGERING OVER THE REGION...AND
LACKING ANY NOTABLE FORCING MECHANISMS...EXPECT ANOTHER RAIN FREE
DAY WITH POPS BELOW 15 PERCENT. TEMPERATURES WILL BE SUPPRESSED
WELL BELOW SEASONAL NORMALS...PEAKING ONLY IN THE MID 80S DESPITE
MOSTLY CLEAR TO PARTLY SKIES. RADIATIONAL COOLING WILL BE
EFFICIENT MONDAY NIGHT CONSIDERING LIGHT WINDS AND MOSTLY CLEAR
SKIES...ALLOWING LOW TEMPERATURES TO ONCE AGAIN FALL INTO THE 60S
ACROSS THE FORECAST AREA.
TUESDAY...THE PATTERN WILL BEGIN TO TRANSITION...AS SURFACE HIGH
PRESSURE CONTINUES TO SHIFT SOUTHWARD AND WEAKEN...WHILE A TROUGH
DEVELOPS OVER THE MID ATLANTIC AND CAROLINAS. HIGH TEMPERATURES
WILL MODERATE A FEW DEGREES INTO THE UPPER 80S AWAY FROM THE
COAST...YET ENOUGH DRY AIR WILL REMAIN TO SUPPRESS CONVECTIVE
DEVELOPMENT ONCE AGAIN. HAVE THUS CAPPED POPS BELOW 15 PERCENT ON
TUESDAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A TROUGH AT THE SURFACE AND ALOFT WILL STEADILY STRENGTHEN ALONG
THE EAST COAST MID TO LATE WEEK...ASSISTING IN THE DESCENT OF A
BACKDOOR FRONT INTO THE AREA BY THURSDAY OR FRIDAY. FAIRLY
SIGNIFICANT TIMING DIFFERENCES IN THE PROGRESSION OF THE FRONT ARE
EVIDENT IN MEDIUM RANGE MODEL SOLUTIONS...LENDING MORE UNCERTAINTY
TO FORECAST DETAILS FOR THE LATE WEEK PERIOD. WILL CONTINUE TO CAP
RAIN CHANCES BELOW 15 PERCENT THROUGH WEDNESDAY NIGHT...BEFORE
MOISTURE AND CONVERGENCE BECOMES ENHANCED AHEAD AND ALONG THE
APPROACHING FRONT THURSDAY AND FRIDAY. WILL REMAIN RATHER
GENERIC WITH POPS FOR THE LATE WEEK PERIOD CONSIDERING MODEL
DISCREPANCIES...INDICATING A SLIGHT CHANCE OF THUNDERSTORMS BY
THURSDAY AFTERNOON AND A SOLID CHANCE BY FRIDAY AFTERNOON. MODELS
ARE IN AGREEMENT THAT THE FRONT WILL LIKELY BE SOUTH OF THE AREA
BY SATURDAY. TEMPERATURES WILL HAVE MODERATED BACK TO NEAR
SEASONAL NORMALS DURING THE EXTENDED PERIOD...WITH HIGHS GENERALLY
IN THE UPPER 80S TO AROUND 90 DEGREES.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS EXPECTED AT THE TERMINALS. WILL BE WATCHING FOR
CONVECTION CROPPING UP LATER TONIGHT ALONG AND AHEAD OF A COLD
FRONT WHICH WILL BE SAGGING SOUTH THROUGH THE CAROLINAS. THE
BETTER CHANCES FROM LATER TONIGHT TO EARLY SAT AFTERNOON APPEAR TO
BE AT KCHS THROUGH MID-MORNING AND FROM LATE MORNING TO LATER IN
THE AFTERNOON AT KSAV. TSTMS POSSIBLE BUT CONFIDENCE IS LOW. FOR
NOW...WE HAVE JUST TIMED VCSH AT KCHS WHERE CONFIDENCE FOR
POSSIBLE IMPACTS IS THE HIGHEST. EXPECT VFR CONDITIONS TO PERSIST
OUTSIDE OF ANY CONVECTIVE RAINS ON SATURDAY.
EXTENDED AVIATION OUTLOOK...THERE IS A GOOD CHANCE OF BRIEF SUB-VFR
CONDITIONS WITH SHOWERS AND THUNDERSTORMS SATURDAY.
&&
.MARINE...
TODAY...LIGHT WINDS WILL GRADUALLY TURN NORTHEAST ACROSS THE SOUTH
CAROLINA WATERS AS A COLD FRONT DROPS SOUTH. THE FRONT LOOKS TO
GET HUNG UP NEAR THE SAVANNAH RIVER ENTRANCE BY EARLY AFTERNOON AS
A WEAK SEA BREEZE CIRCULATION MOVES INLAND. WINDS WILL LIKELY
REMAIN QUITE LIGHT OVER THE GEORGIA WATERS FOR MUCH OF THE DAY
OUTSIDE OF TSTMS. BOTH WINDS AND SEAS WILL REMAIN WELL BELOW SMALL
CRAFT ADVISORY THRESHOLDS...ALTHOUGH WINDS TO 35 KT AND FREQUENT
CLOUD TO WATER LIGHTNING COULD OCCUR WITH ANY TSTMS THAT FORM
AHEAD OF THE FRONT.
TONIGHT...CONDITIONS WILL DETERIORATE OVER THE WATERS TONIGHT AS
THE COLD FRONT FINALLY CLEARS THE SOUTHERN WATERS AND HIGH
PRESSURE WEDGES INTO THE REGION. THE PRESSURE GRADIENT LOOKS TO
TIGHTEN PRETTY SUBSTANTIALLY BY LATE EVENING AND MOST AVAILABLE
GUIDANCE SUPPORTS A MODEST NORTHEAST SURGE WORKING DOWN THE COAST
THROUGH THE OVERNIGHT HOURS. MODELS TYPICALLY UNDERPLAY THIS TYPE
OF PINCHED GRADIENT REGIME AND WITH BOTH MMG AND MME GUIDANCE
PACKAGES ALREADY SUPPORTING WINDS NEAR 20 KT...IT WILL NOT TAKE
MUCH MORE TO GET WINDS INTO FLAG THRESHOLDS. IN ADDITION...SEAS
WILL BUILD QUICKLY IN THE NORTHEAST FLOW WITH LOCAL SWAN OUTPUT
SHOWING 6 FT SEAS REACHING TO WITHIN 15 NM OF THE COAST AFTER
MIDNIGHT. GIVEN THESE FACTORS...WILL HOIST A SMALL CRAFT ADVISORY
FOR BOTH SOUTH CAROLINA NEARSHORE ZONES...EXCLUDING THE CHARLESTON
HARBOR FOR TONIGHT. CONDITIONS LOOK TO REMAIN BELOW THRESHOLDS FOR
THE GEORGIA WATERS AT LEAST THROUGH TONIGHT...ALTHOUGH IT MAY BE
CLOSE.
SUNDAY THROUGH WEDNESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL
CONTINUE INTO SUNDAY...AS THE PRESSURE GRADIENT REMAINS TIGHT
ALONG THE PERIPHERY OF HIGH PRESSURE BUILDING FROM THE NORTH. AT
LEAST MODERATE NORTHEAST FLOW WILL PERSIST INTO MONDAY...BEFORE
THE GRADIENT RELAXES ONCE HIGH PRESSURE BECOMES CENTERED OVER THE
FORECAST AREA. SEAS WILL BUILD TO 3 TO 5 FT NEARSHORE AND 5 TO 6
FT BEYOND 20 NM EARLY SUNDAY...THEN STEADILY SUBSIDE FOR THE
REMAINDER OF THE PERIOD.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 8 PM EDT SUNDAY FOR AMZ352.
SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 8 PM EDT
SUNDAY FOR AMZ350.
&&
$$
ST/WMS
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
120 AM EDT SAT AUG 24 2013
.SYNOPSIS...
A COLD WILL MOVE THROUGH THE AREA TONIGHT AND INTO EARLY SATURDAY.
HIGH PRESSURE WILL BUILD INTO THE REGION OVER THE WEEKEND AND BRING
DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THROUGH 3 AM...CONVECTIVE ACTIVITY STARTING TO PICK UP IN ADVANCE
OF COLD FRONT MOVING THROUGH THE REGION. RUC MODEL SHOWING SHORT
WAVE STRENGTHENING AS IT MOVES S-SE ACROSS THE REGION. CAE RADAR
SHOWING COVERAGE PICKING UP TO THE NORTH OF CAE. DECIDED TO GO
LIKELY IN THE LINE OF ACTIVITY AS IT MOVES SOUTH. OTHERWISE...
BOTH RUC AND NAM MODEL SOUNDINGS GAVE CAPES AROUND 3500 J/KG NEAR
06Z.
REST OF OVERNIGHT PERIOD...WITH FRONT MOVING ON TO THE SOUTH...
THE 20-30 PERCENT POPS STILL LOOKED OK. EXPECT LOWS NEAR 70.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
AS THE MAIN BACKDOOR COLD FRONT CONTINUES PUSHING SOUTHWARD
THROUGH THE AREA...THE BEST CHANCE FOR PRECIPITATION WILL SHIFT TO
THE SOUTHERN HALF OF THE FORECAST AREA AS DRIER AIR TRIES TO
FILTER IN ACROSS THE NORTH. PRECIPITATION WILL COME TO AN END
ACROSS THE AREA BY SATURDAY EVENING AS THE FRONT PUSHES FARTHER TO
THE SOUTH. MAXIMUM TEMPERATURES SLIGHTLY BELOW NORMAL IN THE MID
TO UPPER 80S. OVERNIGHT LOWS SATURDAY NIGHT WILL RANGE FROM THE
MID 60S NORTH TO AROUND 70 SOUTH.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE WEATHER PATTERN REMAINS DRY AS HIGH PRESSURE BEGINS TO BUILD
INTO THE AREA INTO THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE WILL
BUILD ACROSS THE CENTRAL CONUS AND NUDGE EASTWARD AS THE UPPER
TROUGH REMAINS WELL OFF THE EAST COAST. BY LATE WEEK THE UPPER
RIDGE BEGINS TO RETROGRADE TO THE WEST ALLOWING AN UPPER TROUGH TO
REBUILD OVER THE EAST COAST. THIS WILL RESULT IN AN INCREASED
CHANCE FOR PRECIPITATION THURSDAY INTO FRIDAY. HIGH TEMPERATURES
MONDAY THROUGH WEDNESDAY MAINLY IN THE MID TO UPPER 80S...AND
AROUND 90 THURSDAY AND FRIDAY. OVERNIGHT LOWS WILL BE IN THE
MIDDLE TO UPPER 60S EARLY TUESDAY AND WEDNESDAY MORNINGS...AND IN
THE LOWER 70S BY LATE WEEK.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
FRONTAL BOUNDARY ACROSS THE NORTHERN FA WILL PUSH SLOWLY SOUTH
OVERNIGHT...WITH SCT TSRA POSSIBLE OVER THE NEXT FEW HOURS. LATEST
HIGH RESOLUTION MODELS SUGGEST LOWER CLOUDS DEVELOPING TO OUR NE AND
SHIFTING SW INTO OUR FA TOWARDS DAYBREAK. CURRENT OBS CONFIRM SOME
CLOUDS ACROSS NC WITH MAINLY MVFR CIGS. FOR NOW...WILL INDICATE A
PERIOD OF MVFR CIGS FOR OUR TERMINALS LATE TONIGHT AND TOWARDS
DAYBREAK...GRADUALLY LIFTING DURING THE MORNING. IFR CIGS PSBL BUT
WILL WAIT TO INCLUDE IN TAFS IF/WHEN CONFIDENCE WARRANTS. WINDS WILL
SHIFT TO N AND NE BEHIND THE FRONT...BUT LIGHT WINDS ALONG AND AHEAD
OF THE FRONT AT OGB/AGS COULD SPELL A SLIGHT FOG THREAT...BUT THINK
HIGH LEVEL CLOUDINESS WILL PRECLUDE THREAT.
FRONT TO CONTINUE SLOWLY SHIFTING SOUTH TODAY...WITH BETTER
INSTABILITIES AND MOST TSRA LATER TODAY AND THIS AFTERNOON TO BE
MAINLY TO OUR S AND SW. CHANCES TOO LOW TO INCLUDE MENTION IN THE
TAFS AT THIS TIME.
EXTENDED AVIATION OUTLOOK...SATURDAY NIGHT THROUGH THURSDAY...NO
SIGNIFICANT IMPACTS EXPECTED AT THIS TIME.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
109 AM EDT SAT AUG 24 2013
.SYNOPSIS...
A COLD WILL MOVE THROUGH THE AREA TONIGHT AND INTO EARLY SATURDAY.
HIGH PRESSURE WILL BUILD INTO THE REGION OVER THE WEEKEND AND BRING
DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THROUGH 3 AM...CONVECTIVE ACTIVITY STARTING TO PICK UP IN ADVANCE
OF COLD FRONT MOVING THROUGH THE REGION. RUC MODEL SHOWING SHORT
WAVE STRENGTHENING AS IT MOVES S-SE ACROSS THE REGION. CAE RADAR
SHOWING COVERAGE PICKING UP TO THE NORTH OF CAE. DECIDED TO GO
LIKELY IN THE LINE OF ACTIVITY AS IT MOVES SOUTH. OTHERWISE...
BOTH RUC AND NAM MODEL SOUNDINGS GAVE CAPES AROUND 3500 J/KG NEAR
06Z.
REST OF OVERNIGHT PERIOD...WITH FRONT MOVING ON TO THE SOUTH...
THE 20-30 PERCENT POPS STILL LOOKED OK. EXPECT LOWS NEAR 70.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
AS THE MAIN BACKDOOR COLD FRONT CONTINUES PUSHING SOUTHWARD
THROUGH THE AREA...THE BEST CHANCE FOR PRECIPITATION WILL SHIFT TO
THE SOUTHERN HALF OF THE FORECAST AREA AS DRIER AIR TRIES TO
FILTER IN ACROSS THE NORTH. PRECIPITATION WILL COME TO AN END
ACROSS THE AREA BY SATURDAY EVENING AS THE FRONT PUSHES FARTHER TO
THE SOUTH. MAXIMUM TEMPERATURES SLIGHTLY BELOW NORMAL IN THE MID
TO UPPER 80S. OVERNIGHT LOWS SATURDAY NIGHT WILL RANGE FROM THE
MID 60S NORTH TO AROUND 70 SOUTH.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE WEATHER PATTERN REMAINS DRY AS HIGH PRESSURE BEGINS TO BUILD
INTO THE AREA INTO THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE WILL
BUILD ACROSS THE CENTRAL CONUS AND NUDGE EASTWARD AS THE UPPER
TROUGH REMAINS WELL OFF THE EAST COAST. BY LATE WEEK THE UPPER
RIDGE BEGINS TO RETROGRADE TO THE WEST ALLOWING AN UPPER TROUGH TO
REBUILD OVER THE EAST COAST. THIS WILL RESULT IN AN INCREASED
CHANCE FOR PRECIPITATION THURSDAY INTO FRIDAY. HIGH TEMPERATURES
MONDAY THROUGH WEDNESDAY MAINLY IN THE MID TO UPPER 80S...AND
AROUND 90 THURSDAY AND FRIDAY. OVERNIGHT LOWS WILL BE IN THE
MIDDLE TO UPPER 60S EARLY TUESDAY AND WEDNESDAY MORNINGS...AND IN
THE LOWER 70S BY LATE WEEK.
&&
.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...
MAINLY VFR CONDITIONS CONTINUE ACROSS THE AREA THIS EVENING. AT THE
SURFACE...A WEAK SURFACE TROUGH IS LOCATED ACROSS THE MIDLANDS WITH
THE MAIN COLD FRONT ALONG THE CAROLINA BORDER. AHEAD OF THE FRONT
THE AIR MASS IS UNSTABLE AND SCATTERED SHOWERS AND THUNDERSTORMS
HAVE DEVELOPED. DECIDED TO INCLUDE MENTION THUNDERSTORMS IN THE
VICINITY OF CAE AND CUB THROUGH 06Z. WINDS WILL BE VARIABLE...
BUT A GRADUAL WIND SHIFT TO THE NORTH/NORTHEAST WILL OCCUR BEHIND
THE FRONT. WILL MENTION A PERIOD OF MVFR CONDITIONS AT OGB/AGS
SATURDAY MORNING...BUT SOME MIXED SIGNALS WITH POTENTIAL CLOUD
COVER WITH BOUNDARY AND 20 KT LOW LEVEL JET TOWARD MORNING. ON
SATURDAY...EXPECT SCT/BKN CLOUDS BECOMING SCATTERED BY THE
AFTERNOON AS SOME DRIER AIR BEGINS TO MOVE INTO THE REGION FROM
THE NORTH. SURFACE WINDS WILL SHIFT TO THE NE AT 5 TO 10 KNOTS.
EXTENDED AVIATION OUTLOOK...NO RESTRICTIONS TO AVIATION EXPECTED AT
THIS TIME.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1205 AM EDT SAT AUG 24 2013
.SYNOPSIS...
A COLD WILL MOVE THROUGH THE AREA TONIGHT AND INTO EARLY SATURDAY.
HIGH PRESSURE WILL BUILD INTO THE REGION OVER THE WEEKEND AND BRING
DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THROUGH 3 AM...CONVECTIVE ACTIVITY STARTING TO PICK UP IN ADVANCE
OF COLD FRONT MOVING THROUGH THE REGION. ACTIVITY TO THE NORTH OF
CAE AND ON TOWARD CAMDEN. LIGHTNING DETECTION SHOWS SOME
LIGHTNING. BOTH RUC AND NAM MODEL SOUNDINGS GAVE CAPES AROUND 3500
J/KG NEAR 06Z. DECIDED TO INCREASE POPS TO 50 PERCENT BASICALLY
IN A LINE FROM FROM MCCORMICK COUNTY IN THE WEST TO LEXINGTON AND
RICHLAND COUNTIES AND ON EAST TO KERSHAW AND LEE COUNTIES.
REST OF OVERNIGHT PERIOD...WITH FRONT MOVING ON TO THE SOUTH...
THE 20-30 PERCENT POPS STILL LOOKED OK. EXPECT LOWS NEAR 70.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS THE MAIN BACKDOOR COLD FRONT CONTINUES PUSHING SOUTHWARD
THROUGH THE AREA...THE BEST CHANCE FOR PRECIPITATION WILL SHIFT TO
THE SOUTHERN HALF OF THE FORECAST AREA AS DRIER AIR TRIES TO
FILTER IN ACROSS THE NORTH. PRECIPITATION WILL COME TO AN END
ACROSS THE AREA BY SATURDAY EVENING AS THE FRONT PUSHES FARTHER TO
THE SOUTH. MAXIMUM TEMPERATURES SLIGHTLY BELOW NORMAL IN THE MID
TO UPPER 80S. OVERNIGHT LOWS SATURDAY NIGHT WILL RANGE FROM THE
MID 60S NORTH TO AROUND 70 SOUTH.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE WEATHER PATTERN REMAINS DRY AS HIGH PRESSURE BEGINS TO BUILD
INTO THE AREA INTO THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE WILL
BUILD ACROSS THE CENTRAL CONUS AND NUDGE EASTWARD AS THE UPPER
TROUGH REMAINS WELL OFF THE EAST COAST. BY LATE WEEK THE UPPER
RIDGE BEGINS TO RETROGRADE TO THE WEST ALLOWING AN UPPER TROUGH TO
REBUILD OVER THE EAST COAST. THIS WILL RESULT IN AN INCREASED
CHANCE FOR PRECIPITATION THURSDAY INTO FRIDAY. HIGH TEMPERATURES
MONDAY THROUGH WEDNESDAY MAINLY IN THE MID TO UPPER 80S...AND
AROUND 90 THURSDAY AND FRIDAY. OVERNIGHT LOWS WILL BE IN THE
MIDDLE TO UPPER 60S EARLY TUESDAY AND WEDNESDAY MORNINGS...AND IN
THE LOWER 70S BY LATE WEEK.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
MAINLY VFR CONDITIONS CONTINUE ACROSS THE AREA THIS EVENING. AT THE
SURFACE...A WEAK SURFACE TROUGH IS LOCATED ACROSS THE MIDLANDS WITH
THE MAIN COLD FRONT ALONG THE CAROLINA BORDER. AHEAD OF THE FRONT
THE AIR MASS IS UNSTABLE AND SCATTERED SHOWERS AND THUNDERSTORMS
HAVE DEVELOPED. DECIDED TO INCLUDE MENTION THUNDERSTORMS IN THE
VICINITY OF CAE AND CUB THROUGH 06Z. WINDS WILL BE VARIABLE...
BUT A GRADUAL WIND SHIFT TO THE NORTH/NORTHEAST WILL OCCUR BEHIND
THE FRONT. WILL MENTION A PERIOD OF MVFR CONDITIONS AT OGB/AGS
SATURDAY MORNING...BUT SOME MIXED SIGNALS WITH POTENTIAL CLOUD
COVER WITH BOUNDARY AND 20 KT LOW LEVEL JET TOWARD MORNING. ON
SATURDAY...EXPECT SCT/BKN CLOUDS BECOMING SCATTERED BY THE
AFTERNOON AS SOME DRIER AIR BEGINS TO MOVE INTO THE REGION FROM
THE NORTH. SURFACE WINDS WILL SHIFT TO THE NE AT 5 TO 10 KNOTS.
EXTENDED AVIATION OUTLOOK...NO RESTRICTIONS TO AVIATION EXPECTED AT
THIS TIME.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1255 PM MDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1051 AM MDT SAT AUG 24 2013
SOUTH WINDS HAVE INCREASED THROUGH THE MORNING. LATEST HRRR/NAM RUN
SHOWS 850 MB WINDS PEAK UNTIL NOON THEN DECLINE UNTIL LATE
AFTERNOON. AM NOT COMPLETELY CONVINCED THE RELATIVE HUMIDITIES
WILL FALL ENOUGH/WINDS BE GUSTY ENOUGH TO REACH CRITICAL FIRE WEATHER
CONDITIONS...BUT WILL CONTINUE TO MONITOR.
ADDED A MENTION OF ISOLATED STORMS TO WESTERN YUMA AND FAR NORTHWEST
KIT CARSON COUNTY FOR LATE THIS AFTERNOON/EARLY THIS EVENING.
LATEST OBS SHOW A SURFACE TROUGH OVER THAT AREA. POINT SOUNDINGS
INDICATE SOME CAPE TO WORK WITH DURING THE LATE AFTERNOON WHICH MAY
BE ENOUGH FOR AN ISOLATED STORM TO DEVELOP.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOWS 593DM RIDGE CENTERED
OVER THE CENTRAL CONUS...WITH THE MEAN STORM THRACE WELL NORTH AND
WEST OF THE TRI-STATE REGION.
H5 RIDGE WILL STRENGTHEN TO 595-596DM BY SUN/MON AND REMAIN OVER
KS...KEEPING LARGE SCALE SUBSIDENCE IN PLACE...AND GENERALLY STABLE
CONDITIONS ACROSS THE CWA. STRENGTHENING LEE TROUGH WILL KEEP
BREEZY-WINDY CONDITIONS IN PLACE THROUGH EARLY NEXT WEEK AND STRONG
WAA ACROSS OUR CWA. PRIMARY FORECAST CHALLENGE IS HIGH/LOW TEMPS AND
MARGINAL FIRE WEATHER CONDITIONS.
BASED ON H85 TEMPS NEARING 30-31C EACH AFTERNOON WE SHOULD SEE HIGHS
WELL ABOVE NORMAL IN THE UPPER 90S/NEAR 100F EACH DAY. ONCE THIS
PATTERN IS ESTABLISHED WE SHOULD GET A BETTER HANDLE ON MIXING/H85
BIAS WHICH SHOULD MAKE THINGS A LITTLE EASIER...HOWEVER FOR NOW I
KEPT FORECAST CLOSE TO GUIDANCE. REGARDING LOW TEMPS...WITH
OVERNIGHT WINDS LIKELY REMAINING BREEZING (ESPECIALLY EAST) WE
SHOULDNT SEE AS MUCH COOLING AS MOS GUIDANCE WOULD INDICATE...SO I
TRENDED FORECAST TOWARDS ECMWF 2M GUIDANCE WHICH SEEMS TO BETTER
REFLECT THIS WARMER TREND.
REGARDING FIRE WEATHER...USING A CONSERVATIVE MIXING HEIGHT I HAVE
RH VALUES IN THE UPPER TEENS IN THE WEST THROUGH EARLY NEXT WEEK.
WITH LOWE TD/RH VALUES ALONG AND BEHIND TROUGH AXIS AND STRONGER
WINDS TO THE EAST...I AM NOT CURRENTLY ANTICIPATING MEETING THE 3HR
REQUIREMENT FOR RFW.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 1255 PM MDT SAT AUG 24 2013
SUNDAY NIGHT-TUESDAY...UPPER HIGH CENTERED OVER EASTERN
KANSAS/WESTERN MISSOURI WITH A TROUGH ACROSS THE PACIFIC NORTHWEST
INTO CALIFORNIA AT THE BEGINNING OF THE PERIOD. THE UPPER HIGH IS
FORECAST TO RETROGRADE SLOWLY WEST INTO CENTRAL KANSAS WHICH WILL
SHUNT THE BETTER MID LEVEL MOISTURE NEEDED FOR PRECIPITATION WELL
WEST AND NORTHWEST OF THE AREA LEAVING US DRY.
850 TEMPERATURES SLOWLY WARM A FEW DEGREES EACH DAY WITH HIGHS ON
MONDAY IN THE 90S WITH AROUND 101-102 IN THE TRENTON AND MCCOOK
AREAS. ON TUESDAY VERY SIMILAR CONDITIONS ALTHOUGH MAYBE A DEGREE
HIGHER. NO HIGH TEMPERATURE RECORDS EXPECTED AT PRESENT TIME. LOWS
WILL CONTINUE ABOVE NORMAL IN THE 60S...AROUND 70 IN THE HILL CITY
AND NORTON AREAS.
SOUTHERLY BREEZES TO 30 MPH EACH DAY ALSO EXPECTED.
TUESDAY NIGHT-SATURDAY...UPPER HIGH REMAINS CENTERED OVER SOUTH
CENTRAL KANSAS WEDNESDAY SLOWLY MOVING WEST THURSDAY AND BY FRIDAY
EXPECTED TO BE AS FAR WEST AS SOUTH CENTRAL COLORADO/NORTHEAST NEW
MEXICO. FOR SATURDAY LITTLE CHANGE. LITTLE TO NO CHANCE OF PRECIP
EXPECTED AS BULK OF MOISTURE NEEDED FOR PRECIPITATION WILL BE WELL
WEST OF THE AREA.
HIGH TEMPERATURES GENERALLY IN THE 90S WITH A FEW 100S POSSIBLE EACH
DAY. LOWS MILD IN THE 60S...A FEW 70S ACROSS THE FAR NORTHEAST AND
EAST. MAY SEE RECORD HIGHS IN A FEW SPOTS TOWARD THE LATTER END OF
THE EXTENDED PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1125 AM MDT SAT AUG 24 2013
VFR CONDITIONS FORECAST FOR THE 18Z TAFS. SOUTH WINDS CONTINUE TO
BE GUSTY. THE GUSTS SHOULD DECLINE SOME THIS AFTERNOON...BUT NOT
MUCH. SOUNDINGS SHOW THE GUSTS PERSISTING A FEW HOURS AFTER 0Z.
SUNDAY THE WIND SPEEDS WILL BE LOWER DUE TO SLOWER WINDS AT 850MB.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...99
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1129 AM MDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1051 AM MDT SAT AUG 24 2013
SOUTH WINDS HAVE INCREASED THROUGH THE MORNING. LATEST HRRR/NAM RUN
SHOWS 850 MB WINDS PEAK UNTIL NOON THEN DECLINE UNTIL LATE
AFTERNOON. AM NOT COMPLETELY CONVINCED THE RELATIVE HUMIDITIES
WILL FALL ENOUGH/WINDS BE GUSTY ENOUGH TO REACH CRITICAL FIRE WEATHER
CONDITIONS...BUT WILL CONTINUE TO MONITOR.
ADDED A MENTION OF ISOLATED STORMS TO WESTERN YUMA AND FAR NORTHWEST
KIT CARSON COUNTY FOR LATE THIS AFTERNOON/EARLY THIS EVENING.
LATEST OBS SHOW A SURFACE TROUGH OVER THAT AREA. POINT SOUNDINGS
INDICATE SOME CAPE TO WORK WITH DURING THE LATE AFTERNOON WHICH MAY
BE ENOUGH FOR AN ISOLATED STORM TO DEVELOP.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOWS 593DM RIDGE CENTERED
OVER THE CENTRAL CONUS...WITH THE MEAN STORM THRACE WELL NORTH AND
WEST OF THE TRI-STATE REGION.
H5 RIDGE WILL STRENGTHEN TO 595-596DM BY SUN/MON AND REMAIN OVER
KS...KEEPING LARGE SCALE SUBSIDENCE IN PLACE...AND GENERALLY STABLE
CONDITIONS ACROSS THE CWA. STRENGTHENING LEE TROUGH WILL KEEP
BREEZY-WINDY CONDITIONS IN PLACE THROUGH EARLY NEXT WEEK AND STRONG
WAA ACROSS OUR CWA. PRIMARY FORECAST CHALLENGE IS HIGH/LOW TEMPS AND
MARGINAL FIRE WEATHER CONDITIONS.
BASED ON H85 TEMPS NEARING 30-31C EACH AFTERNOON WE SHOULD SEE HIGHS
WELL ABOVE NORMAL IN THE UPPER 90S/NEAR 100F EACH DAY. ONCE THIS
PATTERN IS ESTABLISHED WE SHOULD GET A BETTER HANDLE ON MIXING/H85
BIAS WHICH SHOULD MAKE THINGS A LITTLE EASIER...HOWEVER FOR NOW I
KEPT FORECAST CLOSE TO GUIDANCE. REGARDING LOW TEMPS...WITH
OVERNIGHT WINDS LIKELY REMAINING BREEZING (ESPECIALLY EAST) WE
SHOULDNT SEE AS MUCH COOLING AS MOS GUIDANCE WOULD INDICATE...SO I
TRENDED FORECAST TOWARDS ECMWF 2M GUIDANCE WHICH SEEMS TO BETTER
REFLECT THIS WARMER TREND.
REGARDING FIRE WEATHER...USING A CONSERVATIVE MIXING HEIGHT I HAVE
RH VALUES IN THE UPPER TEENS IN THE WEST THROUGH EARLY NEXT WEEK.
WITH LOWE TD/RH VALUES ALONG AND BEHIND TROUGH AXIS AND STRONGER
WINDS TO THE EAST...I AM NOT CURRENTLY ANTICIPATING MEETING THE 3HR
REQUIREMENT FOR RFW.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
A BROAD UPPER LEVEL RIDGE WILL BE WELL ESTABLISHED BY THE EXTENDED
PERIOD BEGINNING EARLY NEXT WEEK PROVIDING ABOVE NORMAL TEMPS AND
DRY CONDITIONS. IN GENERAL MODEL CONSENSUS HAS BEEN SOLID OVER THE
PAST FEW DAYS FOR THIS PERIOD...WITH THE ONLY REAL UNCERTAINTIES
BEING /1/ MAX TEMPS AND /2/ HOW THE RIDGE WILL EVOLVE LATE IN THE
WEEK.
IT LOOKS LIKE MAX TEMPS WILL PEAK EARLY IN THE WEEK...WITH
850MB TEMPS IN THE LOW 30S C AS THEY HAVE BEEN PROGGED FOR DAYS.
FULL SUNSHINE AND MIXING WILL LEAD TO HIGHS IN THE MID TO UPPER
90S...AND LOWS IN THE MID 60S IN EASTERN COLORADO TO LOW 70S FARTHER
EAST INTO KANSAS.
ADDRESSING THE SECOND POINT...WHILE THE OVERALL
PATTERN HAS BEEN CONSISTENT SOME OF THE FINE DETAILS TOWARDS THE END
OF THE WEEK ARE LOOKING A BIT LESS CERTAIN NOW. WHILE THE ECMWF AND
GEFS WERE MOVING THE RIDGE EAST AT THE END OF THE WEEK IN PAST
RUNS...THE 00Z GUIDANCE FROM GFS/GEFS/ECMWF ARE FAVORING MORE OF A
RETROGRADING RIDGE TO GO FROM CENTERED OVER KANSAS TOWARDS WESTERN
KANSAS. THIS WOULD LEAD TO A LESS FAVORABLE ENVIRONMENT FOR A
SURFACE TROUGH IN EASTERN CO AND ACCOMPANYING DEVELOPMENT OF BREEZY
SURFACE WINDS DURING THE DAY AND A MUCH WEAKER NOCTURNAL LLJ. IF
THIS PATTERN INDEED DEVELOPS THE DRY WEATHER WOULD PROBABLY EXTEND
THROUGH THE END OF THE MONTH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1125 AM MDT SAT AUG 24 2013
VFR CONDITIONS FORECAST FOR THE 18Z TAFS. SOUTH WINDS CONTINUE TO
BE GUSTY. THE GUSTS SHOULD DECLINE SOME THIS AFTERNOON...BUT NOT
MUCH. SOUNDINGS SHOW THE GUSTS PERSISTING A FEW HOURS AFTER 0Z.
SUNDAY THE WIND SPEEDS WILL BE LOWER DUE TO SLOWER WINDS AT 850MB.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...JJM
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1052 AM MDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1051 AM MDT SAT AUG 24 2013
SOUTH WINDS HAVE INCREASED THROUGH THE MORNING. LATEST HRRR/NAM RUN
SHOWS 850 MB WINDS PEAK UNTIL NOON THEN DECLINE UNTIL LATE
AFTERNOON. AM NOT COMPLETELY CONVINCED THE RELATIVE HUMIDITIES
WILL FALL ENOUGH/WINDS BE GUSTY ENOUGH TO REACH CRITICAL FIRE WEATHER
CONDITIONS...BUT WILL CONTINUE TO MONITOR.
ADDED A MENTION OF ISOLATED STORMS TO WESTERN YUMA AND FAR NORTHWEST
KIT CARSON COUNTY FOR LATE THIS AFTERNOON/EARLY THIS EVENING.
LATEST OBS SHOW A SURFACE TROUGH OVER THAT AREA. POINT SOUNDINGS
INDICATE SOME CAPE TO WORK WITH DURING THE LATE AFTERNOON WHICH MAY
BE ENOUGH FOR AN ISOLATED STORM TO DEVELOP.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOWS 593DM RIDGE CENTERED
OVER THE CENTRAL CONUS...WITH THE MEAN STORM THRACE WELL NORTH AND
WEST OF THE TRI-STATE REGION.
H5 RIDGE WILL STRENGTHEN TO 595-596DM BY SUN/MON AND REMAIN OVER
KS...KEEPING LARGE SCALE SUBSIDENCE IN PLACE...AND GENERALLY STABLE
CONDITIONS ACROSS THE CWA. STRENGTHENING LEE TROUGH WILL KEEP
BREEZY-WINDY CONDITIONS IN PLACE THROUGH EARLY NEXT WEEK AND STRONG
WAA ACROSS OUR CWA. PRIMARY FORECAST CHALLENGE IS HIGH/LOW TEMPS AND
MARGINAL FIRE WEATHER CONDITIONS.
BASED ON H85 TEMPS NEARING 30-31C EACH AFTERNOON WE SHOULD SEE HIGHS
WELL ABOVE NORMAL IN THE UPPER 90S/NEAR 100F EACH DAY. ONCE THIS
PATTERN IS ESTABLISHED WE SHOULD GET A BETTER HANDLE ON MIXING/H85
BIAS WHICH SHOULD MAKE THINGS A LITTLE EASIER...HOWEVER FOR NOW I
KEPT FORECAST CLOSE TO GUIDANCE. REGARDING LOW TEMPS...WITH
OVERNIGHT WINDS LIKELY REMAINING BREEZING (ESPECIALLY EAST) WE
SHOULDNT SEE AS MUCH COOLING AS MOS GUIDANCE WOULD INDICATE...SO I
TRENDED FORECAST TOWARDS ECMWF 2M GUIDANCE WHICH SEEMS TO BETTER
REFLECT THIS WARMER TREND.
REGARDING FIRE WEATHER...USING A CONSERVATIVE MIXING HEIGHT I HAVE
RH VALUES IN THE UPPER TEENS IN THE WEST THROUGH EARLY NEXT WEEK.
WITH LOWE TD/RH VALUES ALONG AND BEHIND TROUGH AXIS AND STRONGER
WINDS TO THE EAST...I AM NOT CURRENTLY ANTICIPATING MEETING THE 3HR
REQUIREMENT FOR RFW.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
A BROAD UPPER LEVEL RIDGE WILL BE WELL ESTABLISHED BY THE EXTENDED
PERIOD BEGINNING EARLY NEXT WEEK PROVIDING ABOVE NORMAL TEMPS AND
DRY CONDITIONS. IN GENERAL MODEL CONSENSUS HAS BEEN SOLID OVER THE
PAST FEW DAYS FOR THIS PERIOD...WITH THE ONLY REAL UNCERTAINTIES
BEING /1/ MAX TEMPS AND /2/ HOW THE RIDGE WILL EVOLVE LATE IN THE
WEEK.
IT LOOKS LIKE MAX TEMPS WILL PEAK EARLY IN THE WEEK...WITH
850MB TEMPS IN THE LOW 30S C AS THEY HAVE BEEN PROGGED FOR DAYS.
FULL SUNSHINE AND MIXING WILL LEAD TO HIGHS IN THE MID TO UPPER
90S...AND LOWS IN THE MID 60S IN EASTERN COLORADO TO LOW 70S FARTHER
EAST INTO KANSAS.
ADDRESSING THE SECOND POINT...WHILE THE OVERALL
PATTERN HAS BEEN CONSISTENT SOME OF THE FINE DETAILS TOWARDS THE END
OF THE WEEK ARE LOOKING A BIT LESS CERTAIN NOW. WHILE THE ECMWF AND
GEFS WERE MOVING THE RIDGE EAST AT THE END OF THE WEEK IN PAST
RUNS...THE 00Z GUIDANCE FROM GFS/GEFS/ECMWF ARE FAVORING MORE OF A
RETROGRADING RIDGE TO GO FROM CENTERED OVER KANSAS TOWARDS WESTERN
KANSAS. THIS WOULD LEAD TO A LESS FAVORABLE ENVIRONMENT FOR A
SURFACE TROUGH IN EASTERN CO AND ACCOMPANYING DEVELOPMENT OF BREEZY
SURFACE WINDS DURING THE DAY AND A MUCH WEAKER NOCTURNAL LLJ. IF
THIS PATTERN INDEED DEVELOPS THE DRY WEATHER WOULD PROBABLY EXTEND
THROUGH THE END OF THE MONTH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 522 AM MDT SAT AUG 24 2013
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD AT BOTH KGLD
AND KMCK. WITH LEE TROUGH IN EASTERN COLORADO STRENGTHENING
EXPECT WINDS TO INCREASE THROUGH THE TAF PERIOD...WITH SOUTHERLY
WINDS GUSTING TO 30KT AT BOTH TERMINALS THIS AFTERNOON. WHILE
GUSTY WINDS WILL DIMINISH AROUND SUNSET...SUSTAINED WINDS OVER
12KT WILL CONTINUE THROUGH TONIGHT.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...JJM
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1038 AM MDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1031 AM MDT SAT AUG 24 2013
SOUTH WINDS HAVE INCREASED THROUGH THE MORNING. LATEST HRRR/NAM RUN
SHOWS 850 MB WINDS PEAK UNTIL NOON THEN DECLINE UNTIL LATE
AFTERNOON. AM NOT COMPLETELY CONVINCED THE RELATIVE HUMIDITIES
WILL FALL ENOUGH/WINDS BE GUSTY ENOUGH TO REACH CRITICAL FIRE WEATHER
CONDITIONS...BUT WILL CONTINUE TO MONITOR.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOWS 593DM RIDGE CENTERED
OVER THE CENTRAL CONUS...WITH THE MEAN STORM THRACE WELL NORTH AND
WEST OF THE TRI-STATE REGION.
H5 RIDGE WILL STRENGTHEN TO 595-596DM BY SUN/MON AND REMAIN OVER
KS...KEEPING LARGE SCALE SUBSIDENCE IN PLACE...AND GENERALLY STABLE
CONDITIONS ACROSS THE CWA. STRENGTHENING LEE TROUGH WILL KEEP
BREEZY-WINDY CONDITIONS IN PLACE THROUGH EARLY NEXT WEEK AND STRONG
WAA ACROSS OUR CWA. PRIMARY FORECAST CHALLENGE IS HIGH/LOW TEMPS AND
MARGINAL FIRE WEATHER CONDITIONS.
BASED ON H85 TEMPS NEARING 30-31C EACH AFTERNOON WE SHOULD SEE HIGHS
WELL ABOVE NORMAL IN THE UPPER 90S/NEAR 100F EACH DAY. ONCE THIS
PATTERN IS ESTABLISHED WE SHOULD GET A BETTER HANDLE ON MIXING/H85
BIAS WHICH SHOULD MAKE THINGS A LITTLE EASIER...HOWEVER FOR NOW I
KEPT FORECAST CLOSE TO GUIDANCE. REGARDING LOW TEMPS...WITH
OVERNIGHT WINDS LIKELY REMAINING BREEZING (ESPECIALLY EAST) WE
SHOULDNT SEE AS MUCH COOLING AS MOS GUIDANCE WOULD INDICATE...SO I
TRENDED FORECAST TOWARDS ECMWF 2M GUIDANCE WHICH SEEMS TO BETTER
REFLECT THIS WARMER TREND.
REGARDING FIRE WEATHER...USING A CONSERVATIVE MIXING HEIGHT I HAVE
RH VALUES IN THE UPPER TEENS IN THE WEST THROUGH EARLY NEXT WEEK.
WITH LOWE TD/RH VALUES ALONG AND BEHIND TROUGH AXIS AND STRONGER
WINDS TO THE EAST...I AM NOT CURRENTLY ANTICIPATING MEETING THE 3HR
REQUIREMENT FOR RFW.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
A BROAD UPPER LEVEL RIDGE WILL BE WELL ESTABLISHED BY THE EXTENDED
PERIOD BEGINNING EARLY NEXT WEEK PROVIDING ABOVE NORMAL TEMPS AND
DRY CONDITIONS. IN GENERAL MODEL CONSENSUS HAS BEEN SOLID OVER THE
PAST FEW DAYS FOR THIS PERIOD...WITH THE ONLY REAL UNCERTAINTIES
BEING /1/ MAX TEMPS AND /2/ HOW THE RIDGE WILL EVOLVE LATE IN THE
WEEK.
IT LOOKS LIKE MAX TEMPS WILL PEAK EARLY IN THE WEEK...WITH
850MB TEMPS IN THE LOW 30S C AS THEY HAVE BEEN PROGGED FOR DAYS.
FULL SUNSHINE AND MIXING WILL LEAD TO HIGHS IN THE MID TO UPPER
90S...AND LOWS IN THE MID 60S IN EASTERN COLORADO TO LOW 70S FARTHER
EAST INTO KANSAS.
ADDRESSING THE SECOND POINT...WHILE THE OVERALL
PATTERN HAS BEEN CONSISTENT SOME OF THE FINE DETAILS TOWARDS THE END
OF THE WEEK ARE LOOKING A BIT LESS CERTAIN NOW. WHILE THE ECMWF AND
GEFS WERE MOVING THE RIDGE EAST AT THE END OF THE WEEK IN PAST
RUNS...THE 00Z GUIDANCE FROM GFS/GEFS/ECMWF ARE FAVORING MORE OF A
RETROGRADING RIDGE TO GO FROM CENTERED OVER KANSAS TOWARDS WESTERN
KANSAS. THIS WOULD LEAD TO A LESS FAVORABLE ENVIRONMENT FOR A
SURFACE TROUGH IN EASTERN CO AND ACCOMPANYING DEVELOPMENT OF BREEZY
SURFACE WINDS DURING THE DAY AND A MUCH WEAKER NOCTURNAL LLJ. IF
THIS PATTERN INDEED DEVELOPS THE DRY WEATHER WOULD PROBABLY EXTEND
THROUGH THE END OF THE MONTH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 522 AM MDT SAT AUG 24 2013
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD AT BOTH KGLD
AND KMCK. WITH LEE TROUGH IN EASTERN COLORADO STRENGTHENING
EXPECT WINDS TO INCREASE THROUGH THE TAF PERIOD...WITH SOUTHERLY
WINDS GUSTING TO 30KT AT BOTH TERMINALS THIS AFTERNOON. WHILE
GUSTY WINDS WILL DIMINISH AROUND SUNSET...SUSTAINED WINDS OVER
12KT WILL CONTINUE THROUGH TONIGHT.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...JJM
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
525 AM MDT SAT AUG 24 2013
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOWS 593DM RIDGE CENTERED
OVER THE CENTRAL CONUS...WITH THE MEAN STORM THRACE WELL NORTH AND
WEST OF THE TRI-STATE REGION.
H5 RIDGE WILL STRENGTHEN TO 595-596DM BY SUN/MON AND REMAIN OVER
KS...KEEPING LARGE SCALE SUBSIDENCE IN PLACE...AND GENERALLY STABLE
CONDITIONS ACROSS THE CWA. STRENGTHENING LEE TROUGH WILL KEEP
BREEZY-WINDY CONDITIONS IN PLACE THROUGH EARLY NEXT WEEK AND STRONG
WAA ACROSS OUR CWA. PRIMARY FORECAST CHALLENGE IS HIGH/LOW TEMPS AND
MARGINAL FIRE WEATHER CONDITIONS.
BASED ON H85 TEMPS NEARING 30-31C EACH AFTERNOON WE SHOULD SEE HIGHS
WELL ABOVE NORMAL IN THE UPPER 90S/NEAR 100F EACH DAY. ONCE THIS
PATTERN IS ESTABLISHED WE SHOULD GET A BETTER HANDLE ON MIXING/H85
BIAS WHICH SHOULD MAKE THINGS A LITTLE EASIER...HOWEVER FOR NOW I
KEPT FORECAST CLOSE TO GUIDANCE. REGARDING LOW TEMPS...WITH
OVERNIGHT WINDS LIKELY REMAINING BREEZING (ESPECIALLY EAST) WE
SHOULDNT SEE AS MUCH COOLING AS MOS GUIDANCE WOULD INDICATE...SO I
TRENDED FORECAST TOWARDS ECMWF 2M GUIDANCE WHICH SEEMS TO BETTER
REFLECT THIS WARMER TREND.
REGARDING FIRE WEATHER...USING A CONSERVATIVE MIXING HEIGHT I HAVE
RH VALUES IN THE UPPER TEENS IN THE WEST THROUGH EARLY NEXT WEEK.
WITH LOWE TD/RH VALUES ALONG AND BEHIND TROUGH AXIS AND STRONGER
WINDS TO THE EAST...I AM NOT CURRENTLY ANTICIPATING MEETING THE 3HR
REQUIREMENT FOR RFW.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
A BROAD UPPER LEVEL RIDGE WILL BE WELL ESTABLISHED BY THE EXTENDED
PERIOD BEGINNING EARLY NEXT WEEK PROVIDING ABOVE NORMAL TEMPS AND
DRY CONDITIONS. IN GENERAL MODEL CONSENSUS HAS BEEN SOLID OVER THE
PAST FEW DAYS FOR THIS PERIOD...WITH THE ONLY REAL UNCERTAINTIES
BEING /1/ MAX TEMPS AND /2/ HOW THE RIDGE WILL EVOLVE LATE IN THE
WEEK.
IT LOOKS LIKE MAX TEMPS WILL PEAK EARLY IN THE WEEK...WITH
850MB TEMPS IN THE LOW 30S C AS THEY HAVE BEEN PROGGED FOR DAYS.
FULL SUNSHINE AND MIXING WILL LEAD TO HIGHS IN THE MID TO UPPER
90S...AND LOWS IN THE MID 60S IN EASTERN COLORADO TO LOW 70S FARTHER
EAST INTO KANSAS.
ADDRESSING THE SECOND POINT...WHILE THE OVERALL
PATTERN HAS BEEN CONSISTENT SOME OF THE FINE DETAILS TOWARDS THE END
OF THE WEEK ARE LOOKING A BIT LESS CERTAIN NOW. WHILE THE ECMWF AND
GEFS WERE MOVING THE RIDGE EAST AT THE END OF THE WEEK IN PAST
RUNS...THE 00Z GUIDANCE FROM GFS/GEFS/ECMWF ARE FAVORING MORE OF A
RETROGRADING RIDGE TO GO FROM CENTERED OVER KANSAS TOWARDS WESTERN
KANSAS. THIS WOULD LEAD TO A LESS FAVORABLE ENVIRONMENT FOR A
SURFACE TROUGH IN EASTERN CO AND ACCOMPANYING DEVELOPMENT OF BREEZY
SURFACE WINDS DURING THE DAY AND A MUCH WEAKER NOCTURNAL LLJ. IF
THIS PATTERN INDEED DEVELOPS THE DRY WEATHER WOULD PROBABLY EXTEND
THROUGH THE END OF THE MONTH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 522 AM MDT SAT AUG 24 2013
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD AT BOTH KGLD
AND KMCK. WITH LEE TROUGH IN EASTERN COLORADO STRENGTHENING
EXPECT WINDS TO INCREASE THROUGH THE TAF PERIOD...WITH SOUTHERLY
WINDS GUSTING TO 30KT AT BOTH TERMINALS THIS AFTERNOON. WHILE
GUSTY WINDS WILL DIMINISH AROUND SUNSET...SUSTAINED WINDS OVER
12KT WILL CONTINUE THROUGH TONIGHT.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JJM
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
218 AM MDT SAT AUG 24 2013
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOWS 593DM RIDGE CENTERED
OVER THE CENTRAL CONUS...WITH THE MEAN STORM THRACE WELL NORTH AND
WEST OF THE TRI-STATE REGION.
H5 RIDGE WILL STRENGTHEN TO 595-596DM BY SUN/MON AND REMAIN OVER
KS...KEEPING LARGE SCALE SUBSIDENCE IN PLACE...AND GENERALLY STABLE
CONDITIONS ACROSS THE CWA. STRENGTHENING LEE TROUGH WILL KEEP
BREEZY-WINDY CONDITIONS IN PLACE THROUGH EARLY NEXT WEEK AND STRONG
WAA ACROSS OUR CWA. PRIMARY FORECAST CHALLENGE IS HIGH/LOW TEMPS AND
MARGINAL FIRE WEATHER CONDITIONS.
BASED ON H85 TEMPS NEARING 30-31C EACH AFTERNOON WE SHOULD SEE HIGHS
WELL ABOVE NORMAL IN THE UPPER 90S/NEAR 100F EACH DAY. ONCE THIS
PATTERN IS ESTABLISHED WE SHOULD GET A BETTER HANDLE ON MIXING/H85
BIAS WHICH SHOULD MAKE THINGS A LITTLE EASIER...HOWEVER FOR NOW I
KEPT FORECAST CLOSE TO GUIDANCE. REGARDING LOW TEMPS...WITH
OVERNIGHT WINDS LIKELY REMAINING BREEZING (ESPECIALLY EAST) WE
SHOULDNT SEE AS MUCH COOLING AS MOS GUIDANCE WOULD INDICATE...SO I
TRENDED FORECAST TOWARDS ECMWF 2M GUIDANCE WHICH SEEMS TO BETTER
REFLECT THIS WARMER TREND.
REGARDING FIRE WEATHER...USING A CONSERVATIVE MIXING HEIGHT I HAVE
RH VALUES IN THE UPPER TEENS IN THE WEST THROUGH EARLY NEXT WEEK.
WITH LOWE TD/RH VALUES ALONG AND BEHIND TROUGH AXIS AND STRONGER
WINDS TO THE EAST...I AM NOT CURRENTLY ANTICIPATING MEETING THE 3HR
REQUIREMENT FOR RFW.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 217 AM MDT SAT AUG 24 2013
A BROAD UPPER LEVEL RIDGE WILL BE WELL ESTABLISHED BY THE EXTENDED
PERIOD BEGINNING EARLY NEXT WEEK PROVIDING ABOVE NORMAL TEMPS AND
DRY CONDITIONS. IN GENERAL MODEL CONSENSUS HAS BEEN SOLID OVER THE
PAST FEW DAYS FOR THIS PERIOD...WITH THE ONLY REAL UNCERTAINTIES
BEING /1/ MAX TEMPS AND /2/ HOW THE RIDGE WILL EVOLVE LATE IN THE
WEEK.
IT LOOKS LIKE MAX TEMPS WILL PEAK EARLY IN THE WEEK...WITH
850MB TEMPS IN THE LOW 30S C AS THEY HAVE BEEN PROGGED FOR DAYS.
FULL SUNSHINE AND MIXING WILL LEAD TO HIGHS IN THE MID TO UPPER
90S...AND LOWS IN THE MID 60S IN EASTERN COLORADO TO LOW 70S FARTHER
EAST INTO KANSAS.
ADDRESSING THE SECOND POINT...WHILE THE OVERALL
PATTERN HAS BEEN CONSISTENT SOME OF THE FINE DETAILS TOWARDS THE END
OF THE WEEK ARE LOOKING A BIT LESS CERTAIN NOW. WHILE THE ECMWF AND
GEFS WERE MOVING THE RIDGE EAST AT THE END OF THE WEEK IN PAST
RUNS...THE 00Z GUIDANCE FROM GFS/GEFS/ECMWF ARE FAVORING MORE OF A
RETROGRADING RIDGE TO GO FROM CENTERED OVER KANSAS TOWARDS WESTERN
KANSAS. THIS WOULD LEAD TO A LESS FAVORABLE ENVIRONMENT FOR A
SURFACE TROUGH IN EASTERN CO AND ACCOMPANYING DEVELOPMENT OF BREEZY
SURFACE WINDS DURING THE DAY AND A MUCH WEAKER NOCTURNAL LLJ. IF
THIS PATTERN INDEED DEVELOPS THE DRY WEATHER WOULD PROBABLY EXTEND
THROUGH THE END OF THE MONTH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1148 PM MDT FRI AUG 23 2013
VFR CONDITIONS ARE EXPECTED AT BOTH MCK AND GLD THROUGH THE TAF
PERIOD. SOUTH WINDS WILL INCREASE AFTER 14Z AND WILL REMAIN GUSTY
THROUGH ABOUT 02Z. AFTER ABOUT 02Z...WINDS WILL BECOME LIGHT OUT
OF THE SOUTH AGAIN.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JJM
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
613 PM EDT SAT AUG 24 2013
.SYNOPSIS...
HIGH PRESSURE AND PLEASANT WEATHER WILL CONTINUE THROUGH THE
WEEKEND. AN UPPER-LEVEL DISTURBANCE WILL APPROACH EARLY NEXT WEEK
AND WILL GIVE US THE CHANCE OF SHOWERS AND STORMS. TEMPERATURES
WILL CLIMB ABOVE NORMAL BY THE END OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
600 PM UPDATE...
DEW POINTS CONTINUE TO SLOWLY DROP. NUDGED MIN TEMPS DOWN ACROSS
NORTH WITH LOWER TD/S. BROUGHT IN A LITTLE MORE CLOUDS (CIRRUS)
TOWARD MORNING. HRRR SUGGESTING SOME BLOW OFF DEBRIS FROM SYSTEM
JUST NORTH OF GREAT LAKES. KEPT A FEW MORE CLOUDS RIDGES
APPALACHIAN PLATEAU COUNTIES. WITH EAST TO NORTHEAST FLOW COULD
CONTINUE A FEW UP-SLOPE CLOUDS.
PREVIOUS DISCUSSION FOLLOWS...
DRY ADIABATIC CONDITIONS FROM CCL TO SFC HAVE DEVELOPED A SCT CU
FIELD ACROSS THE HIGHER TERRAIN AND POINTS S OF I-70. THIS FIELD
WILL CONTINUE TO GROW THIS AFTN AS TEMPS CLIMB INTO THE M-U 70S.
DAYTIME DRIVEN CU WILL WANE WITH SUNSET...LEAVING A CLR- MCLR SKY.
CROSSOVER TEMPS OF M-U 50S WOULD NOT YIELD FOG FORMATION OVERNIGHT
EVEN IN THE DEEPER HOLLOWS OF THE NRN WV MTNS.
H5 HEIGHTS BUILD SUN AS ANTICYCLONE OVER THE MIDWEST SHIFTS A
LITTLE E. BUFR SOUNDINGS ILLUSTRATE AN INC IN MID AND HIGH CLOUDS
DURING THE AFTN HRS FROM THE NW AS MSTR SPILLS OVER TOP THE NRN
PERIPHERY OF THE RIDGE. ANOTHER FACTOR FOR INC HIGH CLOUDS IS UPR
LVL DIV DEPICTED BY NCEP MDLS THE SECOND HALF OF SUN. CU TRIGGER
TEMPS WILL BE IN THE UPR 70S AGAIN TMRW AND WE WILL SURPASS THOSE
NUMBERS BY LUNCH TIME...SO ANOTHER CU FIELD CAN BE ANTICIPATED.
TWEAKED INHERITED SKY GRIDS HOWEVER FOR A LARGE PART MID AND HIGH
CLOUDS WILL BE NON - OPAQUED SO ROLLING WITH ANOTHER MSNNY FCST.
NAM12BC GRIDS USED FOR MAXT SUN...WHILE MOSGUIDE BC USED FOR MINT
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
BENIGN WEATHER PERSISTS THROUGH MONDAY WITH MID-LVL HIGH PRESSURE
STILL IN CONTROL OF OUR WEATHER DESPITE ITS WESTWARD PROGRESSION.
BELT OF STRONGER H7-H5 WINDS MAKES STEERING FLOW NW...ALLOWING A
BAROCLINIC ZONE TO DROP THROUGH THE EMPIRE STATE INTO NRN PA BY
MON EVE. STILL THINK AMOUNT OF DRY AIR INDICATED BUT -1 STD PWATS
WILL ALLOW FOR ANOTHER PCPN FREE MONDAY...HWVR AMOUNT OF INCOMING
SOLAR RADIATION WILL BE DIMINISHED THROUGH THE DAY ESPECIALLY
ACROSS I-80 CORRIDOR. H8 TEMPS UNDER LIGHT SW WINDS IN THE BL
CLIMB TO 16C...WHICH WILL PUSH TEMPS INTO THE L-M 80S. THIS COULD
BE THE WARMEST DAY TO DATE OF THE ENTIRE MONTH IF WE HIT 85F AT
PIT...WHICH SOME STATISTICAL GUIDANCE SUGGESTS.
H5 ANTICYCLONE WILL STRENGTHEN THRU WED...LEAVING FCST AREA IN
NWLY FLOW ALOFT. SVRL SHRTWV TROFS WILL PROGRESS THRU THIS FLOW
DURG THE MON NGT-WED TIMEFRAME AS DP MSTR RETURNS TO THE RGN.
PRIMARY FACTOR INFLUENCING THE CVRG AND INTENSITY OF CNVCTN DURG
THIS TIME WILL BE MID-LVL LAPSE RATES. DYNAMICALLY...PATTERN WILL
BCM MORE FAVORABLE FOR SVR WX AS WIND FIELD STRENGTHENS. BOTH
ECMWF AND GFS DEPICT CNVCTN ASSOCIATED WITH WAVES PASSING THRU MON
EVE AND TUE AFTN-EVE. POPS WERE ADJUSTED APPROPRIATELY TO REFLECT
THIS PSBLTY.
ECMWF AND GFS DIFFER ON TIMING OF SHRTWV TROF ON WED. OWING TO
UNCERTAINTIES IN TIMING...HAVE NOT INCRD POPS CONSIDERABLY ON WED
OR MENTIONED SVR WX IN HWO. BUT THIS PSBLTY WILL NEED TO BE
MONITORED CLOSELY.
CONTD MAXIMA IN THE LOW-MID 80S XPCD THRU WED. MINIMA WILL INCR
MARKEDLY MON NGT AND TUE OWING TO LOW-LVL MSTR ADVCTN...WITH LOWS
IN THE MID-UPR 60S LKLY MANY AREAS TUE NGT.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
BY LATE IN THE LONG TERM...UPPER-LEVEL RIDGE WILL SHIFT BACK TO
THE EAST AND SURFACE HIGH WILL TAKE OVER.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
HIGH CONFIDENCE VFR FCST. WINDS BELOW 7KTS THROUGH THE PERIOD.
.OUTLOOK.../16Z SUNDAY THROUGH WEDNESDAY/...
BRIEF IFR WEATHER IS POSSIBLE MON NGT - TUE WITH THE NEXT WEATHER
SYSTEM.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1200 AM EDT MON AUG 26 2013
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 350 PM EDT SUN AUG 25 2013
A WARM FRONT WILL MOVE EAST OF THE AREA THIS EVENING PUTTING
SOUTHWEST MICHIGAN IN WARM AND HUMID AIR UNTIL THE COLD FRONT
COMES THROUGH WEDNESDAY MORNING. EXPECT PERIODS OF THUNDERSTORMS
FROM MONDAY AFTERNOON INTO WEDNESDAY MORNING. FOR MOST OF THE AREA
THE GREATEST RISK OF SIGNIFICANT RAINFALL IS TUESDAY INTO TUESDAY
NIGHT. WARM DRY WEATHER WILL THEN PREVAIL UNTIL THE NEXT WARM
FRONT COMES THROUGH NEXT WEEKEND. THAT COULD BE THE HOTTEST
WEATHER OF THE SUMMER.
&&
.UPDATE...
ISSUED AT 1023 PM EDT SUN AUG 25 2013
WITH DEW POINTS MAINLY IN THE MID 60S...LOWERED MIN TEMPS SLIGHTLY
FOR OVERNIGHT...OTHERWISE LITTLE.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 350 PM EDT SUN AUG 25 2013
WE ARE WATCHING TWO SIGNIFICANT FEATURES THIS AFTERNOON... FIRST IS
THE POTENTIAL FOR THUNDERSTORMS ONCE WE ARE SOLIDLY IN THE WARM
AND HUMID AIR... THEN THE SECOND ISSUE IS JUST HOW HOT IT GET THE
NEXT TWO AFTERNOONS.
FIRST THE CONVECTION ISSUE. IT NOW SEEMS THE FRONTAL BOUNDARY OVER
THE UPPER PENINSULA WILL NOT MAKE MUCH PROGRESS SOUTH TONIGHT SO I
DO NOT EXPECT THE CONVECTION ASSOCIATED WITH IT TO MAKE MUCH
PROGRESS EITHER. THIS IS SHOWN BY THE NSSL AND SPC WAF... AND THE
HRRR MODELS AS WELL AS THE RAP MODEL. WELL THE CONVECTION WILL
MOVE SOUTH FROM WHERE IT IS BUT IT SHOULD NOT GET MUCH FATHER
SOUTH THEN ROUTE 10 BY MORNING SO I HAVE LOW CHANCE POPS UP THERE.
THAT IS BASED ON THE LOW LEVEL JET AXIS NOT GETTING MUCH FARTHER
SOUTH THAN CAD/HTL BY 12Z. NOTE THAT THERE ARE TWO PRIMARY
SHORTWAVES DRIVING ALL OF THIS. THIS FIRST ONE IS MOVING EAST WITH
THE CONVECTION NORTHEAST OF LAKE HURON. THE SECOND IS LESS
OBVIOUS BUT IS CURRENTLY OVER THE DAKOTAS AND HEADING EAST OVER
THE TOP OF THE UPPER RIDGE. IT IS THAT SHORTWAVE THAT WILL SPARK
THE CONVECTION OVER NRN WI AND THE UPPER PENINSULA THIS EVENING
INTO THE OVERNIGHT HOURS. THAT CONVECTION WILL DRIVE THE COLD
FRONT SOUTH TONIGHT AND MAY BRING THUNDERSTORMS TO OUR NORTHERN
CWA BY SUNRISE.
THIS LEAD SHORTWAVE CREATES A SORT OF COLD FRONT /WARM FRONT SET
UP. SO THE COLD FRONT TRAILING THE LEAD SHORTWAVE IS WHAT DIVES
THE CONVECTION SOUTH TONIGHT INTO MONDAY. THEN THE NEXT UPSTREAM
WAVE PUSHES IT ALL BACK NORTH AS A WARM FRONT MONDAY NIGHT. THERE
IS AN UPPER LEVEL JET ASSOCIATED WITH THIS SO I WOULD EXPECT
ANOTHER ROUND OF CONVECTION MONDAY NIGHT INTO TUESDAY MORNING WITH
THAT. HOWEVER... IF THE COLD FRONT DOES NOT GET TOO FAR SOUTH
MONDAY... THEN MOST OF THE STORMS SHOULD WELL NORTH OF INTERSTATE
96 MONDAY NIGHT.
FINALLY THE SHORTWAVE OVER NV CURRENTLY CLIMBS THE UPPER RIDGE AND
DIVES DOWN THE FRONT SIDE OF IT TUESDAY AND THAT BRINGS A MORE
SIGNIFICANT COLD FRONT THROUGH THE AREA BY EARLY WEDNESDAY. IT IS
THAT NV SHORTWAVE THAT I BELIEVE WILL BRING OUR BEST SHOT FOR SIGNIFICANT
RAINFALL. THIS WILL LIKELY BE IN THE TUESDAY AFTERNOON INTO
TUESDAY NIGHT TIME FRAME. IT WOULD BE THEN THAT THERE WOULD BE THE
GREATEST RISK OF STRONG TO SEVERE STORMS. DEEP LAYER SHEAR IS IN
THE 30 TO 40 KNOT RANGE DURING THAT TIME AND MIX LAYER CAPES
AROUND 1500 J/KG. WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES
THERE IS LITTLE QUESTION IF WE GET THUNDERSTORMS MINOR FLOODING OF
AREAS WITH POOR DRAINAGE IS A REAL THREAT.
AS FOR HOW HOT IT WILL GET... THE 850 TEMPS ARE AROUND 21C MONDAY
AND TUESDAY. THAT WOULD SUPPORT HIGHS IN LOWER 90S FOR SURE. ALSO THE
1000/925 MB THICKNESS VALUES SUGGEST MID 90S ACTUALLY. THE ONLY
THING THAT WILL KEEP OUR TEMPERATURES FROM GETTING THAT WARM IS IF
THERE IS TO MUCH CONVECTIVE DEBRIS CLOUDS AROUND. WHICH IS A REAL
PROBLEM FOR THIS FORECAST AS THE COLD FRONT WILL COME CLOSE TO US
MONDAY AFTERNOON AND EARLY EVENING. MOS TEMP FORECASTS KEEP HIGHS IN
THE 80S BOTH DAY BUT GIVEN HOW WARM THE THICKNESS IS AND 850 TEMPS
I HAVE A REAL PROBLEM FORECASTING HIGHS SO LOW. SO WE HAVE TO WAIT
AND SEE JUST HOW MUCH CLOUDS GET GENERATED FROM THE UPSTREAM
CONVECTION TO SEE HOW HOT IT REALLY GETS THE NEXT TWO DAYS.
MEANWHILE I WILL GO WITH HIGHS IN THE LOWER 90S FOR NOW AND CALL
THAT GOOD.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 350 PM EDT SUN AUG 25 2013
THE GOING MID SUMMER-LIKE FORECAST AND MAINLY DRY CONDITIONS IN THE
LONG TERM CONTINUES TO LOOK ON TRACK.
WE CONTINUE TO EXPECT THAT THE FRONT SHOULD BE EXITING THE FCST AREA
TO THE SOUTH RIGHT AROUND 12Z WED. THIS OCCURS AS THE UPPER HEIGHTS
LOWER SLIGHTLY OVER THE AREA...AND NW FLOW ALOFT COMMENCES. THIS
WILL RESULT IN DRY CONDITIONS...TEMPS DROPPING A COUPLE OF DEGREES
AND SLIGHTLY LOWER HUMIDITY LEVELS AS WE COULD POTENTIALLY SEE ON
TUE. H850 TEMPS DROP TO AROUND 18-19C WHICH WOULD STILL SUPPORT
HIGHS IN THE MID 80S TO AROUND 90.
THE MODELS CONTINUE TO INDICATE SOME SORT OF MCS DEVELOPING TO OUR W
LATE THU AND MOVING SE ALONG THE UPPER RIDGE ON FRI. WE HAVE BETTER
CONFIDENCE AT THIS TIME THAT THIS COMPLEX WILL END UP SW OF THE AREA
CLOSER TO THE BETTER INSTABILITY SOUTH OF THE FRONT. VERY WARM AND
DRY CONDITIONS ARE EXPECTED ONCE AGAIN FOR FRI.
WE EXPECT TO SEE ANOTHER SURGE OF HEAT THEN BEGINNING NEXT WEEKEND.
WE WILL SEE THE UPPER RIDGE AXIS BUILD BACK OVER THE AREA BY NEXT
SUN AS SHORT WAVE ENERGY MOVING ACROSS CANADA WILL SHIFT IT E/SE.
INCREASING LOW LEVEL SW FLOW AHEAD OF THE SFC LOW WILL HELP TO
ADVECT THE HOT TEMPS OVER THE PLAINS OVER OUR AREA. H850 TEMPS ARE
FCST TO INCREASE TO THE LOWER 20S C BY NEXT SUN. WE COULD SEE MAX
TEMPS WELL INTO THE 90S IF THIS PLAYS OUT THIS WAY. WE HAVE GONE
SOMEWHAT CONSERVATIVE FOR NOW WITH HIGHS IN THE LOWER TO MID 90S.
THE TRANSITION OF THIS AIR MASS INTO THE AREA COULD BRING A LOW CHC
OF PCPN TO THE AREA ON SUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1158 PM EDT SUN AUG 25 2013
THUNDERSTORMS SHOULD REMAIN NORTH OF CENTRAL MICHIGAN THROUGH
TUESDAY. KEPT THE TAFS VFR FOR NOW WITH NO STORMS OR DEBRIS
CLOUDS. SOUTHWEST WINDS WILL INCREASE MONDAY MORNING WITH GUSTS
OVER 20 KNOTS BY AFTERNOON.
&&
.MARINE...
ISSUED AT 350 PM EDT SUN AUG 25 2013
WITH THE WINDS IN THE BOUNDARY LAYER FORECAST TO BE 20 - 35 KNOTS
INTO MONDAY EVENING IT SEEMS MORE THAN REASONABLE TO KEEP THE
BEACH HAZARD STATEMENT GOING AND THE SMALL CRAFT ADVISORY.
&&
.HYDROLOGY...
ISSUED AT 350 PM EDT SUN AUG 25 2013
WHILE LARGE AREA HEAVY RAINFALL IS NOT EXPECTED... THERE IS LITTLE
QUESTION WITH ALL THE PRECIPITABLE WATER OVERHEAD THE NEXT 2-3
DAYS... IF WE DO SEE ANY THUNDERSTORMS SOME VERY HEAVY RAINFALL
SHOULD BE EXPECTED AS WELL AS LOCALIZED FLOODING IF THE STORMS
MOVE OVER AN URBAN AREA.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH LATE MONDAY NIGHT FOR MIZ037-043-
050-056.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR LMZ846>849.
&&
$$
UPDATE...JK
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...OSTUNO
HYDROLOGY...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1023 PM EDT SUN AUG 25 2013
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 350 PM EDT SUN AUG 25 2013
A WARM FRONT WILL MOVE EAST OF THE AREA THIS EVENING PUTTING
SOUTHWEST MICHIGAN IN WARM AND HUMID AIR UNTIL THE COLD FRONT
COMES THROUGH WEDNESDAY MORNING. EXPECT PERIODS OF THUNDERSTORMS
FROM MONDAY AFTERNOON INTO WEDNESDAY MORNING. FOR MOST OF THE AREA
THE GREATEST RISK OF SIGNIFICANT RAINFALL IS TUESDAY INTO TUESDAY
NIGHT. WARM DRY WEATHER WILL THEN PREVAIL UNTIL THE NEXT WARM
FRONT COMES THROUGH NEXT WEEKEND. THAT COULD BE THE HOTTEST
WEATHER OF THE SUMMER.
&&
.UPDATE...
ISSUED AT 1023 PM EDT SUN AUG 25 2013
WITH DEW POINTS MAINLY IN THE MID 60S...LOWERED MIN TEMPS SLIGHTLY
FOR OVERNIGHT...OTHERWISE LITTLE.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 350 PM EDT SUN AUG 25 2013
WE ARE WATCHING TWO SIGNIFICANT FEATURES THIS AFTERNOON... FIRST IS
THE POTENTIAL FOR THUNDERSTORMS ONCE WE ARE SOLIDLY IN THE WARM
AND HUMID AIR... THEN THE SECOND ISSUE IS JUST HOW HOT IT GET THE
NEXT TWO AFTERNOONS.
FIRST THE CONVECTION ISSUE. IT NOW SEEMS THE FRONTAL BOUNDARY OVER
THE UPPER PENINSULA WILL NOT MAKE MUCH PROGRESS SOUTH TONIGHT SO I
DO NOT EXPECT THE CONVECTION ASSOCIATED WITH IT TO MAKE MUCH
PROGRESS EITHER. THIS IS SHOWN BY THE NSSL AND SPC WAF... AND THE
HRRR MODELS AS WELL AS THE RAP MODEL. WELL THE CONVECTION WILL
MOVE SOUTH FROM WHERE IT IS BUT IT SHOULD NOT GET MUCH FATHER
SOUTH THEN ROUTE 10 BY MORNING SO I HAVE LOW CHANCE POPS UP THERE.
THAT IS BASED ON THE LOW LEVEL JET AXIS NOT GETTING MUCH FARTHER
SOUTH THAN CAD/HTL BY 12Z. NOTE THAT THERE ARE TWO PRIMARY
SHORTWAVES DRIVING ALL OF THIS. THIS FIRST ONE IS MOVING EAST WITH
THE CONVECTION NORTHEAST OF LAKE HURON. THE SECOND IS LESS
OBVIOUS BUT IS CURRENTLY OVER THE DAKOTAS AND HEADING EAST OVER
THE TOP OF THE UPPER RIDGE. IT IS THAT SHORTWAVE THAT WILL SPARK
THE CONVECTION OVER NRN WI AND THE UPPER PENINSULA THIS EVENING
INTO THE OVERNIGHT HOURS. THAT CONVECTION WILL DRIVE THE COLD
FRONT SOUTH TONIGHT AND MAY BRING THUNDERSTORMS TO OUR NORTHERN
CWA BY SUNRISE.
THIS LEAD SHORTWAVE CREATES A SORT OF COLD FRONT /WARM FRONT SET
UP. SO THE COLD FRONT TRAILING THE LEAD SHORTWAVE IS WHAT DIVES
THE CONVECTION SOUTH TONIGHT INTO MONDAY. THEN THE NEXT UPSTREAM
WAVE PUSHES IT ALL BACK NORTH AS A WARM FRONT MONDAY NIGHT. THERE
IS AN UPPER LEVEL JET ASSOCIATED WITH THIS SO I WOULD EXPECT
ANOTHER ROUND OF CONVECTION MONDAY NIGHT INTO TUESDAY MORNING WITH
THAT. HOWEVER... IF THE COLD FRONT DOES NOT GET TOO FAR SOUTH
MONDAY... THEN MOST OF THE STORMS SHOULD WELL NORTH OF INTERSTATE
96 MONDAY NIGHT.
FINALLY THE SHORTWAVE OVER NV CURRENTLY CLIMBS THE UPPER RIDGE AND
DIVES DOWN THE FRONT SIDE OF IT TUESDAY AND THAT BRINGS A MORE
SIGNIFICANT COLD FRONT THROUGH THE AREA BY EARLY WEDNESDAY. IT IS
THAT NV SHORTWAVE THAT I BELIEVE WILL BRING OUR BEST SHOT FOR SIGNIFICANT
RAINFALL. THIS WILL LIKELY BE IN THE TUESDAY AFTERNOON INTO
TUESDAY NIGHT TIME FRAME. IT WOULD BE THEN THAT THERE WOULD BE THE
GREATEST RISK OF STRONG TO SEVERE STORMS. DEEP LAYER SHEAR IS IN
THE 30 TO 40 KNOT RANGE DURING THAT TIME AND MIX LAYER CAPES
AROUND 1500 J/KG. WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES
THERE IS LITTLE QUESTION IF WE GET THUNDERSTORMS MINOR FLOODING OF
AREAS WITH POOR DRAINAGE IS A REAL THREAT.
AS FOR HOW HOT IT WILL GET... THE 850 TEMPS ARE AROUND 21C MONDAY
AND TUESDAY. THAT WOULD SUPPORT HIGHS IN LOWER 90S FOR SURE. ALSO THE
1000/925 MB THICKNESS VALUES SUGGEST MID 90S ACTUALLY. THE ONLY
THING THAT WILL KEEP OUR TEMPERATURES FROM GETTING THAT WARM IS IF
THERE IS TO MUCH CONVECTIVE DEBRIS CLOUDS AROUND. WHICH IS A REAL
PROBLEM FOR THIS FORECAST AS THE COLD FRONT WILL COME CLOSE TO US
MONDAY AFTERNOON AND EARLY EVENING. MOS TEMP FORECASTS KEEP HIGHS IN
THE 80S BOTH DAY BUT GIVEN HOW WARM THE THICKNESS IS AND 850 TEMPS
I HAVE A REAL PROBLEM FORECASTING HIGHS SO LOW. SO WE HAVE TO WAIT
AND SEE JUST HOW MUCH CLOUDS GET GENERATED FROM THE UPSTREAM
CONVECTION TO SEE HOW HOT IT REALLY GETS THE NEXT TWO DAYS.
MEANWHILE I WILL GO WITH HIGHS IN THE LOWER 90S FOR NOW AND CALL
THAT GOOD.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 350 PM EDT SUN AUG 25 2013
THE GOING MID SUMMER-LIKE FORECAST AND MAINLY DRY CONDITIONS IN THE
LONG TERM CONTINUES TO LOOK ON TRACK.
WE CONTINUE TO EXPECT THAT THE FRONT SHOULD BE EXITING THE FCST AREA
TO THE SOUTH RIGHT AROUND 12Z WED. THIS OCCURS AS THE UPPER HEIGHTS
LOWER SLIGHTLY OVER THE AREA...AND NW FLOW ALOFT COMMENCES. THIS
WILL RESULT IN DRY CONDITIONS...TEMPS DROPPING A COUPLE OF DEGREES
AND SLIGHTLY LOWER HUMIDITY LEVELS AS WE COULD POTENTIALLY SEE ON
TUE. H850 TEMPS DROP TO AROUND 18-19C WHICH WOULD STILL SUPPORT
HIGHS IN THE MID 80S TO AROUND 90.
THE MODELS CONTINUE TO INDICATE SOME SORT OF MCS DEVELOPING TO OUR W
LATE THU AND MOVING SE ALONG THE UPPER RIDGE ON FRI. WE HAVE BETTER
CONFIDENCE AT THIS TIME THAT THIS COMPLEX WILL END UP SW OF THE AREA
CLOSER TO THE BETTER INSTABILITY SOUTH OF THE FRONT. VERY WARM AND
DRY CONDITIONS ARE EXPECTED ONCE AGAIN FOR FRI.
WE EXPECT TO SEE ANOTHER SURGE OF HEAT THEN BEGINNING NEXT WEEKEND.
WE WILL SEE THE UPPER RIDGE AXIS BUILD BACK OVER THE AREA BY NEXT
SUN AS SHORT WAVE ENERGY MOVING ACROSS CANADA WILL SHIFT IT E/SE.
INCREASING LOW LEVEL SW FLOW AHEAD OF THE SFC LOW WILL HELP TO
ADVECT THE HOT TEMPS OVER THE PLAINS OVER OUR AREA. H850 TEMPS ARE
FCST TO INCREASE TO THE LOWER 20S C BY NEXT SUN. WE COULD SEE MAX
TEMPS WELL INTO THE 90S IF THIS PLAYS OUT THIS WAY. WE HAVE GONE
SOMEWHAT CONSERVATIVE FOR NOW WITH HIGHS IN THE LOWER TO MID 90S.
THE TRANSITION OF THIS AIR MASS INTO THE AREA COULD BRING A LOW CHC
OF PCPN TO THE AREA ON SUN.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 717 PM EDT SUN AUG 25 2013
SOUTHWEST WINDS WILL DECREASE THIS EVENING WITH GUSTS OVER 20
KNOTS RETURNING MONDAY MORNING. THUNDERSTORMS SHOULD REMAIN NORTH
OF CENTRAL MICHIGAN OVERNIGHT BUT THIS WILL HAVE TO BE WATCHED AS
THERE IS A LOW CHANCE THAT THEY COULD SURGE SOUTH AFTER MIDNIGHT.
KEPT THE TAFS VFR FOR NOW WITH NO STORMS OR DEBRIS CLOUDS.
&&
.MARINE...
ISSUED AT 350 PM EDT SUN AUG 25 2013
WITH THE WINDS IN THE BOUNDARY LAYER FORECAST TO BE 20 - 35 KNOTS
INTO MONDAY EVENING IT SEEMS MORE THAN REASONABLE TO KEEP THE
BEACH HAZARD STATEMENT GOING AND THE SMALL CRAFT ADVISORY.
&&
.HYDROLOGY...
ISSUED AT 350 PM EDT SUN AUG 25 2013
WHILE LARGE AREA HEAVY RAINFALL IS NOT EXPECTED... THERE IS LITTLE
QUESTION WITH ALL THE PRECIPITABLE WATER OVERHEAD THE NEXT 2-3
DAYS... IF WE DO SEE ANY THUNDERSTORMS SOME VERY HEAVY RAINFALL
SHOULD BE EXPECTED AS WELL AS LOCALIZED FLOODING IF THE STORMS
MOVE OVER AN URBAN AREA.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH LATE MONDAY NIGHT FOR MIZ037-043-
050-056.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR LMZ846>849.
&&
$$
UPDATE...JK
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...OSTUNO
HYDROLOGY...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
718 PM EDT SUN AUG 25 2013
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 350 PM EDT SUN AUG 25 2013
A WARM FRONT WILL MOVE EAST OF THE AREA THIS EVENING PUTTING
SOUTHWEST MICHIGAN IN WARM AND HUMID AIR UNTIL THE COLD FRONT
COMES THROUGH WEDNESDAY MORNING. EXPECT PERIODS OF THUNDERSTORMS
FROM MONDAY AFTERNOON INTO WEDNESDAY MORNING. FOR MOST OF THE AREA
THE GREATEST RISK OF SIGNIFICANT RAINFALL IS TUESDAY INTO TUESDAY
NIGHT. WARM DRY WEATHER WILL THEN PREVAIL UNTIL THE NEXT WARM
FRONT COMES THROUGH NEXT WEEKEND. THAT COULD BE THE HOTTEST
WEATHER OF THE SUMMER.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 350 PM EDT SUN AUG 25 2013
WE ARE WATCHING TWO SIGNIFICANT FEATURES THIS AFTERNOON... FIRST IS
THE POTENTIAL FOR THUNDERSTORMS ONCE WE ARE SOLIDLY IN THE WARM
AND HUMID AIR... THEN THE SECOND ISSUE IS JUST HOW HOT IT GET THE
NEXT TWO AFTERNOONS.
FIRST THE CONVECTION ISSUE. IT NOW SEEMS THE FRONTAL BOUNDARY OVER
THE UPPER PENINSULA WILL NOT MAKE MUCH PROGRESS SOUTH TONIGHT SO I
DO NOT EXPECT THE CONVECTION ASSOCIATED WITH IT TO MAKE MUCH
PROGRESS EITHER. THIS IS SHOWN BY THE NSSL AND SPC WAF... AND THE
HRRR MODELS AS WELL AS THE RAP MODEL. WELL THE CONVECTION WILL
MOVE SOUTH FROM WHERE IT IS BUT IT SHOULD NOT GET MUCH FATHER
SOUTH THEN ROUTE 10 BY MORNING SO I HAVE LOW CHANCE POPS UP THERE.
THAT IS BASED ON THE LOW LEVEL JET AXIS NOT GETTING MUCH FARTHER
SOUTH THAN CAD/HTL BY 12Z. NOTE THAT THERE ARE TWO PRIMARY
SHORTWAVES DRIVING ALL OF THIS. THIS FIRST ONE IS MOVING EAST WITH
THE CONVECTION NORTHEAST OF LAKE HURON. THE SECOND IS LESS
OBVIOUS BUT IS CURRENTLY OVER THE DAKOTAS AND HEADING EAST OVER
THE TOP OF THE UPPER RIDGE. IT IS THAT SHORTWAVE THAT WILL SPARK
THE CONVECTION OVER NRN WI AND THE UPPER PENINSULA THIS EVENING
INTO THE OVERNIGHT HOURS. THAT CONVECTION WILL DRIVE THE COLD
FRONT SOUTH TONIGHT AND MAY BRING THUNDERSTORMS TO OUR NORTHERN
CWA BY SUNRISE.
THIS LEAD SHORTWAVE CREATES A SORT OF COLD FRONT /WARM FRONT SET
UP. SO THE COLD FRONT TRAILING THE LEAD SHORTWAVE IS WHAT DIVES
THE CONVECTION SOUTH TONIGHT INTO MONDAY. THEN THE NEXT UPSTREAM
WAVE PUSHES IT ALL BACK NORTH AS A WARM FRONT MONDAY NIGHT. THERE
IS AN UPPER LEVEL JET ASSOCIATED WITH THIS SO I WOULD EXPECT
ANOTHER ROUND OF CONVECTION MONDAY NIGHT INTO TUESDAY MORNING WITH
THAT. HOWEVER... IF THE COLD FRONT DOES NOT GET TOO FAR SOUTH
MONDAY... THEN MOST OF THE STORMS SHOULD WELL NORTH OF INTERSTATE
96 MONDAY NIGHT.
FINALLY THE SHORTWAVE OVER NV CURRENTLY CLIMBS THE UPPER RIDGE AND
DIVES DOWN THE FRONT SIDE OF IT TUESDAY AND THAT BRINGS A MORE
SIGNIFICANT COLD FRONT THROUGH THE AREA BY EARLY WEDNESDAY. IT IS
THAT NV SHORTWAVE THAT I BELIEVE WILL BRING OUR BEST SHOT FOR SIGNIFICANT
RAINFALL. THIS WILL LIKELY BE IN THE TUESDAY AFTERNOON INTO
TUESDAY NIGHT TIME FRAME. IT WOULD BE THEN THAT THERE WOULD BE THE
GREATEST RISK OF STRONG TO SEVERE STORMS. DEEP LAYER SHEAR IS IN
THE 30 TO 40 KNOT RANGE DURING THAT TIME AND MIX LAYER CAPES
AROUND 1500 J/KG. WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES
THERE IS LITTLE QUESTION IF WE GET THUNDERSTORMS MINOR FLOODING OF
AREAS WITH POOR DRAINAGE IS A REAL THREAT.
AS FOR HOW HOT IT WILL GET... THE 850 TEMPS ARE AROUND 21C MONDAY
AND TUESDAY. THAT WOULD SUPPORT HIGHS IN LOWER 90S FOR SURE. ALSO THE
1000/925 MB THICKNESS VALUES SUGGEST MID 90S ACTUALLY. THE ONLY
THING THAT WILL KEEP OUR TEMPERATURES FROM GETTING THAT WARM IS IF
THERE IS TO MUCH CONVECTIVE DEBRIS CLOUDS AROUND. WHICH IS A REAL
PROBLEM FOR THIS FORECAST AS THE COLD FRONT WILL COME CLOSE TO US
MONDAY AFTERNOON AND EARLY EVENING. MOS TEMP FORECASTS KEEP HIGHS IN
THE 80S BOTH DAY BUT GIVEN HOW WARM THE THICKNESS IS AND 850 TEMPS
I HAVE A REAL PROBLEM FORECASTING HIGHS SO LOW. SO WE HAVE TO WAIT
AND SEE JUST HOW MUCH CLOUDS GET GENERATED FROM THE UPSTREAM
CONVECTION TO SEE HOW HOT IT REALLY GETS THE NEXT TWO DAYS.
MEANWHILE I WILL GO WITH HIGHS IN THE LOWER 90S FOR NOW AND CALL
THAT GOOD.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 350 PM EDT SUN AUG 25 2013
THE GOING MID SUMMER-LIKE FORECAST AND MAINLY DRY CONDITIONS IN THE
LONG TERM CONTINUES TO LOOK ON TRACK.
WE CONTINUE TO EXPECT THAT THE FRONT SHOULD BE EXITING THE FCST AREA
TO THE SOUTH RIGHT AROUND 12Z WED. THIS OCCURS AS THE UPPER HEIGHTS
LOWER SLIGHTLY OVER THE AREA...AND NW FLOW ALOFT COMMENCES. THIS
WILL RESULT IN DRY CONDITIONS...TEMPS DROPPING A COUPLE OF DEGREES
AND SLIGHTLY LOWER HUMIDITY LEVELS AS WE COULD POTENTIALLY SEE ON
TUE. H850 TEMPS DROP TO AROUND 18-19C WHICH WOULD STILL SUPPORT
HIGHS IN THE MID 80S TO AROUND 90.
THE MODELS CONTINUE TO INDICATE SOME SORT OF MCS DEVELOPING TO OUR W
LATE THU AND MOVING SE ALONG THE UPPER RIDGE ON FRI. WE HAVE BETTER
CONFIDENCE AT THIS TIME THAT THIS COMPLEX WILL END UP SW OF THE AREA
CLOSER TO THE BETTER INSTABILITY SOUTH OF THE FRONT. VERY WARM AND
DRY CONDITIONS ARE EXPECTED ONCE AGAIN FOR FRI.
WE EXPECT TO SEE ANOTHER SURGE OF HEAT THEN BEGINNING NEXT WEEKEND.
WE WILL SEE THE UPPER RIDGE AXIS BUILD BACK OVER THE AREA BY NEXT
SUN AS SHORT WAVE ENERGY MOVING ACROSS CANADA WILL SHIFT IT E/SE.
INCREASING LOW LEVEL SW FLOW AHEAD OF THE SFC LOW WILL HELP TO
ADVECT THE HOT TEMPS OVER THE PLAINS OVER OUR AREA. H850 TEMPS ARE
FCST TO INCREASE TO THE LOWER 20S C BY NEXT SUN. WE COULD SEE MAX
TEMPS WELL INTO THE 90S IF THIS PLAYS OUT THIS WAY. WE HAVE GONE
SOMEWHAT CONSERVATIVE FOR NOW WITH HIGHS IN THE LOWER TO MID 90S.
THE TRANSITION OF THIS AIR MASS INTO THE AREA COULD BRING A LOW CHC
OF PCPN TO THE AREA ON SUN.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 717 PM EDT SUN AUG 25 2013
SOUTHWEST WINDS WILL DECREASE THIS EVENING WITH GUSTS OVER 20
KNOTS RETURNING MONDAY MORNING. THUNDERSTORMS SHOULD REMAIN NORTH
OF CENTRAL MICHIGAN OVERNIGHT BUT THIS WILL HAVE TO BE WATCHED AS
THERE IS A LOW CHANCE THAT THEY COULD SURGE SOUTH AFTER MIDNIGHT.
KEPT THE TAFS VFR FOR NOW WITH NO STORMS OR DEBRIS CLOUDS.
&&
.MARINE...
ISSUED AT 350 PM EDT SUN AUG 25 2013
WITH THE WINDS IN THE BOUNDARY LAYER FORECAST TO BE 20 - 35 KNOTS
INTO MONDAY EVENING IT SEEMS MORE THAN REASONABLE TO KEEP THE
BEACH HAZARD STATEMENT GOING AND THE SMALL CRAFT ADVISORY.
&&
.HYDROLOGY...
ISSUED AT 350 PM EDT SUN AUG 25 2013
WHILE LARGE AREA HEAVY RAINFALL IS NOT EXPECTED... THERE IS LITTLE
QUESTION WITH ALL THE PRECIPITABLE WATER OVERHEAD THE NEXT 2-3
DAYS... IF WE DO SEE ANY THUNDERSTORMS SOME VERY HEAVY RAINFALL
SHOULD BE EXPECTED AS WELL AS LOCALIZED FLOODING IF THE STORMS
MOVE OVER AN URBAN AREA.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH LATE MONDAY NIGHT FOR MIZ037-043-
050-056.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR LMZ846>849.
&&
$$
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...OSTUNO
HYDROLOGY...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
942 PM CDT SUN AUG 25 2013
.MESOSCALE DISCUSSION...
ISSUED AT 925 PM CDT SUN AUG 25 2013
SHOWER AND THUNDERSTORM DEVELOPMENT CONTINUES ACROSS NORTHERN MN
LATE THIS EVENING. THEY HAVE SHOWN SOME SIGNS OF BUILDING
SOUTHWARD TOWARD CENTRAL MN/NWRN WI IN THE PAST HOUR OR SO WHERE
PW IS MAXIMIZED AND CIN IS MINIMIZED. HOWEVER...00Z MPX SOUNDING
SHOWS STRONG CAPPING A BIT FURTHER SOUTH UNDERNEATH THERMAL
RIDGING...THUS DEVELOPMENT IS MUCH MORE CONDITIONAL AND DELAYED.
SHOULD THE ACTIVITY NORTH ACQUIRE A COLD POOL...THE PROBABILITY OF
DEVELOPMENT FURTHER SOUTH WILL INCREASE ACROSS FAR ERN MN AND WRN WI.
ADDITIONAL STORMS HAVE DEVELOPED OVER NORTHERN SD ON THE LEADING
EDGE OF AN EXTENSIVE MOISTURE RICH AIR PLUME ORIGINATING FROM
FORMER TROPICAL STORM IVO OF THE EASTERN PACIFIC. AS THIS PLUME
TRANSLATES EASTWARD...COULD SEE A FEW STORMS FIRE ACROSS CENTRAL
MN OVERNIGHT.
MAIN THREAT WITH STORMS TONIGHT WILL BE HEAVY RAIN. HIGH FREEZING
LEVELS AND PW VALUES NEAR 2 INCHES BRING EFFICIENT RAIN PROCESSES.
BACK BUILDING/SLOW MOVING CELLS COULD BRING LOCAL FLASH FLOODING.
PRESENCE OF 2000 J/KG TO 3000 J/KG OF MUCAPE MAY ALSO BRING A
THREAT FOR DAMAGING WINDS...ALTHOUGH THE LACK OF SIGNIFICANT SHEAR
AND HIGH FREEZING LEVELS WILL LIKELY LIMIT HAIL THREAT.
&&
.SYNOPSIS...
ISSUED AT 359 PM CDT SUN AUG 25 2013
NOT MUCH HAS CHANGED IN THE UPPER LEVELS IN THE LAST 24 HRS...WITH A
598 DM HIGH CENTERED OVER MISSOURI THAT IS STILL FLANKED BY TROUGHS
ON EITHER COAST OF NOAM. ACROSS THE ROCKIES...WATER VAPOR IMAGERY IS
SHOWING A TROPICAL MOISTURE PLUME FROM THE REMNANTS OF AN ERN
PACIFIC TROPICAL SYSTEM CURRENTLY OVER THE BAJA PENINSULA THAT IS
NOW WORKING ITS WAY AROUND THE WRN PERIPHERY OF THE MISSOURI HIGHS
AND ALREADY MOVING UP INTO WYOMING...LIKELY REACHING THE UPPER MS
VALLEY MONDAY.
AT THE SFC A TROUGH OF LOW PRESSURE WAS SITUATED FROM CENTRAL SODAK
NE TO NEAR INL. STRONG PRESSURE GRADIENT IS STILL IN PLACE...WITH
BREEZY SOUTHWEST WINDS CONTINUING. WITH TEMPS IN THE LOW TO MID 90S
AND DEWPS IN THE LOW TO MID 70S...STARTING TO SEE HEAT INDICES CLIMB
TO OVER 100 DEGREES...WITH VALUES OF MLCAPE UP SAFELY IN THE HEALTHY
RANGE BETWEEN 3500 AND 6000 J/KG.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 359 PM CDT SUN AUG 25 2013
AS CAN BE IMAGINED...WITH A CAPPED...WEAKLY FORCED...HIGH CAPE
ENVIRONMENT...CONFIDENCE IS STILL QUITE LOW ON WHERE/IF CONVECTION
WILL FIRE LATER THIS EVENING. ONE THING IS FOR SURE...PRESENCE OF
ENOUGH INSTABILITY IS NOT AN ISSUE!
WHEN LOOKING AT THE SPC MESO ANALYSIS AND SATELLITE ALONG
WITH A FEW INSTABILITY/MOISTURE TRANSPORT FIELDS FROM THE
DETERMINISTIC MODELS YOU CAN GET A SENSE OF HOW THINGS SHOULD TRY TO
UNFOLD THIS EVENING. FROM THE MESO ANALYSIS SIDE OF THINGS...THERE
IS A GRADIENT IN THE MLCAPE FIELD ACROSS CENTRAL MN...WHICH IS
COINCIDENT WITH THE NRN EDGE OF THE STEEPER MID LEVEL LAPSE RATES
ASSOCIATED WITH AN EML AND STRONGER CAPPING. JUST NORTH OF THE
MLCAPE GRADIENT...THE 20Z ANALYSIS SHOWS H7 DEWPOINTS BETTER THAN
10C ACROSS THE SRN END OF THE DLH/FGF FORECAST AREAS. WITHIN THIS
ZONE OF HIGHER MOISTURE AT H7 MOISTURE...A SHALLOW CU FIELD HAS
DEVELOPED BENEATH A FEW BITS OF ACCUS THAT STRETCH FROM AROUND
FERGUS FALLS OVER TOWARD DULUTH. BEST GUESS RIGHT NOW IS THAT IF
STORMS ARE TO DEVELOP...IT WILL BE WITHIN THIS ZONE...LIKELY CLOSER
TO 00Z.
IN ADDITION...MODELS SHOW THE LLJ AND ASSOCIATED MOISTURE ADVECTION
VEERING SOME AND SAGGING SOUTH THROUGH THE NIGHT. THE AREA OF CLOUDS
REFERENCED ABOVE ALSO SITS ON THE NRN EDGE OF THE MAIN MOISTURE
TRANSPORT PLUME AT H85...WHICH MOST GUIDANCE SHOW COMING DOWN TO
ABOUT I-94 OVERNIGHT. IF SOMETHING CAN GET GOING...THE PRESENCE OF
THE LLJ SHOULD KEEP THE ACTIVITY GOING THROUGH MUCH OF THE NIGHT.
WITH THE RAP AND MOST OTHER MODELS SHOWING THE STRONGEST MOISTURE
TRANSPORT IN THE H85-H7 LAYER RESIDING OVER ERN MN/WRN
WI...CONTINUED TO ADVERTISE LIKELY POPS IN ERN AREAS...THAT TAIL OFF
TO LOW CHANCE POPS IN THE WEST FOR TONIGHT.
FROM THE SEVERE END OF THINGS...AN ENVIRONMENT ASSOCIATED WITH HIGH
MOISTURE CONTENT /PWATS CURRENT NEAR 2 INCHES/...DEEP MELTING
LAYERS...AND WEAK SHEAR MEANS LARGE HAIL WILL BE TOUGH TO COME BY.
HOWEVER...VALUES OF DCAPE UP AROUND 1500 J/KG INDICATES THE WIND
POTENTIAL IS CERTAINLY STILL THERE IF WE CAN GET ANY DEEP MOIST
CONVECTION GOING.
WHAT HAPPENS TONIGHT WILL GO A LONG WAY IN DETERMINING WHERE ANY
POTENTIAL CONVECTION CAN FIRE UP MONDAY AFTERNOON. THE QUESTION FOR
TOMORROW IS FAR SOUTH CAN THE BOUNDARY SLOWLY HEADING FOR CENTRAL MN
MAKE IT TONIGHT. IF WE DO SEE A GOOD AMOUNT OF CONVECTION
OVERNIGHT...THEN THERE IS A GOOD CHANCE THAT THE BOUNDARY CAN MAKE
IT DOWN TO ABOUT I-94. IF WE DO NOT SEE MUCH CONVECTION
TONIGHT...THEN IN ALL LIKELIHOOD...THE BOUNDARY WILL REMAIN NORTH OF
THE MPX AREA...WITH ANOTHER DAY OF CAPED SUNNY SKIES ENSUING. THE
NAM/SREF WOULD SUPPORT THE SRN IDEA...WHILE THE GFS/ECMWF/GEM GO
NORTH. FOR NOW WENT WITH CHANCE POPS AFTER 21Z FOR AREAS NORTH OF
I-94. FROM THE SEVERE PERSPECTIVE...ABOUT THE ONLY THING DIFFERENT
ABOUT MONDAY COMPARED TO TODAY IS THAT THE BELT OF STRONGER
WESTERLIES WILL HAVE SAGGED SOUTH A BIT MORE...INCREASING THE AMOUNT
OF DEEP LAYER SHEAR...WHICH WILL MAKE THE RISK OF LARGE HAIL A BIT
HIGHER OWING TO THE CHANCE OF GETTING AT LEAST WEAK SUPERCELL
STRUCTURES GOING.
LAST STOP IS WITH TEMPERATURES. OVERNIGHT...EXPECT CENTRAL MN TO
COOL A FEW DEGREES MORE THAN THEY DID LAST NIGHT AS THE PRESSURE
GRADIENT WEAKENS...ALLOWING FOR SOME RADIATIONAL COOLING TONIGHT.
STILL...WITH DEWPS AROUND 70...MOST PLACES SHOULD STILL STAY ABOVE
THAT MARK. FOR THE TWIN CITIES AND PLACES FARTHER SOUTH/EAST...WINDS
WILL REMAIN IN PLACE /THOUGH NOT AS STRONG AS LAST NIGHT/...WHICH
WILL KEEP SOME FORM OF MIXING GOING AND ONCE AGAIN MAKE IT A
STRUGGLE FOR A LOT OF PLACES TO DROP BELOW 80 WITHOUT THE HELP OF
RAIN.
FOR HIGHS TOMORROW...925-850 MB TEMPS ACTUALLY INCREASE A DEGREE OR
TWO AS COMPARED TO TODAY...WHICH WOULD THEORETICALLY MEAN WE COULD
GET A DEGREE OR TWO WARMER. HOWEVER...THERE IS THE POTENTIAL FOR A
BIG BUST WITH HIGHS TOMORROW DEPENDING ON WHAT HAPPENS WITH STORMS
TONIGHT. IF WE DO END UP SEEING FAIRLY WIDESPREAD AND ROBUST
CONVECTION OVERNIGHT...THIS WOULD LIKELY LEAVE BEHIND PLENTY OF
DEBRIS COLD COVER...PUTTING A DAMPER ON TEMPERATURES. THE HIRES NMM
EAST DOES EXACTLY THAT WITH CONVECTION OVERNIGHT. THE RESULTING
CLOUD COVER IT GENERATED FOR THE NEXT DAY RESULTED IN IT ONLY
GENERATING HIGHS IN THE MID/UPPER 80S. AT THE OTHER END OF THE
SCALE...A NIGHT OF LITTLE CONVECTION WILL RESULT IN ANOTHER DAY OF
LOTS OF SUN. IN THAT CASE...THEN HIGHS TOMORROW WOULD BE A DEGREE OR
TWO WARMER THAN TODAY...WITH HIGHS IN THE MID/UPPER 90S AND A FEW
100 DEGREE READINGS NOT OUT OF THE QUESTION IN WRN MN. AT ANY
RATE...DID NOT SEE ANYTHING GLARING CHANGE WITH THE TEMP FORECAST
TODAY THAT REQUIRED ANY CHANGES IN THE GOING HEAT HEADLINES.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 359 PM CDT SUN AUG 25 2013
LONG TERM TRENDS CONTINUE TO SHOW HOT AND HUMID CONDITIONS WILL
CONTINUE THROUGH AT LEAST TUESDAY. LOCATION OF FRONTAL BOUNDARY
MONDAY NIGHT WILL DETERMINE TO WHAT EXTENT/LOCATION CONVECTIVE ACTIVITY
WILL DEVELOP OVER THE CWA. VARIOUS DETERMINISTIC MODELS SHOW THIS
BOUNDARY LIFTING SLOWLY BACK NORTH MONDAY NIGHT AND INTO TUESDAY
AS WEAK COOL FRONT/SURFACE LOW MOVES THROUGH THE AREA. WILL
CONTINUE THE CHANCE POPS OVER THE NORTHEAST THIRD OF THE AREA FOR
TUESDAY...WHICH SHOULD EXIT THE CWA BY TUESDAY EVENING. EXPECT
TEMPERATURES TO RANGE IN THE MID/SOME UPPER 90S AND DEWPOINTS
POOLING AHEAD OF BOUNDARY INTO THE LOWER 70S. HEAT INDEX VALUES
WILL RANGE 100F TO 105F WITH THE CURRENT HEAT ADVISORY/WARNING
STILL LOOKING GOOD CONTINUING THROUGH TUESDAY.
SOME COOLING BEHIND THE FRONT LINGERING INTO FRIDAY...MAINLY OVER
THE EASTERN PORTION OF THE CWA. RIDGING ALOFT DEVELOPS THEREAFTER
WITH SURFACE FRONT MEANDERING OVER CENTRAL MINNESOTA AGAIN INTO
THE WEEKEND. THE 12Z ECMWF IS SLOWER BUILDING THE UPPER RIDGE TO
THE EAST...WITH THE MAIN SURGE COMING NEXT SUNDAY. THE GFS BUILDS
IN NORTH BY SATURDAY. WILL GO ALONG WITH PRESENT TREND OF BRINGING
THE 90S BACK INTO THE AREA FOR SATURDAY AND SUNDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 659 PM CDT SUN AUG 25 2013
TSRA DEVELOPMENT AT TAF ISSUANCE TIME WAS RATHER SPARCE AND
CONFINED TO NORTHERN MN. THINK ADDITIONAL DEVELOPMENT WILL TAKE
PLACE LATER THIS EVENING AND DRIFT SOUTH ACROSS ERN MN AND WRN WI
LATE TONIGHT. CONFIDENCE ON COVERAGE IS LOW AND CONDITIONAL ON
WHETHER THERE WILL BE ENOUGH FORCING. INSTABILITY IS RATHER
HIGH...SO STORMS MAY DEVELOP QUICK AND PRODUCE VERY HEAVY RAIN.
KEPT THE MENTION OUT OF WESTERN TAF SITES...BUT MAINTAINED PROB30
FOR MSP/STC AND VCTS FOR RNH/EAU. IT APPEARS MORE STORMS ACROSS
THE WRN DAKOTAS WILL WEAKEN BEFORE REACHING MN OVERNIGHT.
KMSP...PUSHED BACK THE TIMING OF STORMS SEVERAL HOURS TONIGHT DUE
TO LIMITED ACTIVITY ONGOING AND STRONG CAPPING. ANY TSRA WOULD BE
LATE TONIGHT AS OUTFLOWS FROM STORMS OVER NORTHERN MN DRIFT
SOUTHWARD.
/OUTLOOK FOR KMSP/
TUE...VFR. WIND SW 5-10 KT...BECOMING W/NW IN AFTERNOON.
WED...VFR. WIND NE 5 KT.
THU...VFR. ISOLD SHRA/TS POSSIBLE. WINDS SE 5 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ054>070-073>078-082>085-091>093.
HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ041>045-
047>053.
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ014>016-
023>028.
&&
$$
MESOSCALE...BORGHOFF
SYNOPSIS...MPG
SHORT TERM...MPG
LONG TERM...DWE
AVIATION...BORGHOFF
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
729 PM CDT SUN AUG 25 2013
.SYNOPSIS...
ISSUED AT 359 PM CDT SUN AUG 25 2013
NOT MUCH HAS CHANGED IN THE UPPER LEVELS IN THE LAST 24 HRS...WITH A
598 DM HIGH CENTERED OVER MISSOURI THAT IS STILL FLANKED BY TROUGHS
ON EITHER COAST OF NOAM. ACROSS THE ROCKIES...WATER VAPOR IMAGERY IS
SHOWING A TROPICAL MOISTURE PLUME FROM THE REMNANTS OF AN ERN
PACIFIC TROPICAL SYSTEM CURRENTLY OVER THE BAJA PENINSULA THAT IS
NOW WORKING ITS WAY AROUND THE WRN PERIPHERY OF THE MISSOURI HIGHS
AND ALREADY MOVING UP INTO WYOMING...LIKELY REACHING THE UPPER MS
VALLEY MONDAY.
AT THE SFC A TROUGH OF LOW PRESSURE WAS SITUATED FROM CENTRAL SODAK
NE TO NEAR INL. STRONG PRESSURE GRADIENT IS STILL IN PLACE...WITH
BREEZY SOUTHWEST WINDS CONTINUING. WITH TEMPS IN THE LOW TO MID 90S
AND DEWPS IN THE LOW TO MID 70S...STARTING TO SEE HEAT INDICES CLIMB
TO OVER 100 DEGREES...WITH VALUES OF MLCAPE UP SAFELY IN THE HEALTHY
RANGE BETWEEN 3500 AND 6000 J/KG.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 359 PM CDT SUN AUG 25 2013
AS CAN BE IMAGINED...WITH A CAPPED...WEAKLY FORCED...HIGH CAPE
ENVIRONMENT...CONFIDENCE IS STILL QUITE LOW ON WHERE/IF CONVECTION
WILL FIRE LATER THIS EVENING. ONE THING IS FOR SURE...PRESENCE OF
ENOUGH INSTABILITY IS NOT AN ISSUE!
WHEN LOOKING AT THE SPC MESO ANALYSIS AND SATELLITE ALONG
WITH A FEW INSTABILITY/MOISTURE TRANSPORT FIELDS FROM THE
DETERMINISTIC MODELS YOU CAN GET A SENSE OF HOW THINGS SHOULD TRY TO
UNFOLD THIS EVENING. FROM THE MESO ANALYSIS SIDE OF THINGS...THERE
IS A GRADIENT IN THE MLCAPE FIELD ACROSS CENTRAL MN...WHICH IS
COINCIDENT WITH THE NRN EDGE OF THE STEEPER MID LEVEL LAPSE RATES
ASSOCIATED WITH AN EML AND STRONGER CAPPING. JUST NORTH OF THE
MLCAPE GRADIENT...THE 20Z ANALYSIS SHOWS H7 DEWPOINTS BETTER THAN
10C ACROSS THE SRN END OF THE DLH/FGF FORECAST AREAS. WITHIN THIS
ZONE OF HIGHER MOISTURE AT H7 MOISTURE...A SHALLOW CU FIELD HAS
DEVELOPED BENEATH A FEW BITS OF ACCUS THAT STRETCH FROM AROUND
FERGUS FALLS OVER TOWARD DULUTH. BEST GUESS RIGHT NOW IS THAT IF
STORMS ARE TO DEVELOP...IT WILL BE WITHIN THIS ZONE...LIKELY CLOSER
TO 00Z.
IN ADDITION...MODELS SHOW THE LLJ AND ASSOCIATED MOISTURE ADVECTION
VEERING SOME AND SAGGING SOUTH THROUGH THE NIGHT. THE AREA OF CLOUDS
REFERENCED ABOVE ALSO SITS ON THE NRN EDGE OF THE MAIN MOISTURE
TRANSPORT PLUME AT H85...WHICH MOST GUIDANCE SHOW COMING DOWN TO
ABOUT I-94 OVERNIGHT. IF SOMETHING CAN GET GOING...THE PRESENCE OF
THE LLJ SHOULD KEEP THE ACTIVITY GOING THROUGH MUCH OF THE NIGHT.
WITH THE RAP AND MOST OTHER MODELS SHOWING THE STRONGEST MOISTURE
TRANSPORT IN THE H85-H7 LAYER RESIDING OVER ERN MN/WRN
WI...CONTINUED TO ADVERTISE LIKELY POPS IN ERN AREAS...THAT TAIL OFF
TO LOW CHANCE POPS IN THE WEST FOR TONIGHT.
FROM THE SEVERE END OF THINGS...AN ENVIRONMENT ASSOCIATED WITH HIGH
MOISTURE CONTENT /PWATS CURRENT NEAR 2 INCHES/...DEEP MELTING
LAYERS...AND WEAK SHEAR MEANS LARGE HAIL WILL BE TOUGH TO COME BY.
HOWEVER...VALUES OF DCAPE UP AROUND 1500 J/KG INDICATES THE WIND
POTENTIAL IS CERTAINLY STILL THERE IF WE CAN GET ANY DEEP MOIST
CONVECTION GOING.
WHAT HAPPENS TONIGHT WILL GO A LONG WAY IN DETERMINING WHERE ANY
POTENTIAL CONVECTION CAN FIRE UP MONDAY AFTERNOON. THE QUESTION FOR
TOMORROW IS FAR SOUTH CAN THE BOUNDARY SLOWLY HEADING FOR CENTRAL MN
MAKE IT TONIGHT. IF WE DO SEE A GOOD AMOUNT OF CONVECTION
OVERNIGHT...THEN THERE IS A GOOD CHANCE THAT THE BOUNDARY CAN MAKE
IT DOWN TO ABOUT I-94. IF WE DO NOT SEE MUCH CONVECTION
TONIGHT...THEN IN ALL LIKELIHOOD...THE BOUNDARY WILL REMAIN NORTH OF
THE MPX AREA...WITH ANOTHER DAY OF CAPED SUNNY SKIES ENSUING. THE
NAM/SREF WOULD SUPPORT THE SRN IDEA...WHILE THE GFS/ECMWF/GEM GO
NORTH. FOR NOW WENT WITH CHANCE POPS AFTER 21Z FOR AREAS NORTH OF
I-94. FROM THE SEVERE PERSPECTIVE...ABOUT THE ONLY THING DIFFERENT
ABOUT MONDAY COMPARED TO TODAY IS THAT THE BELT OF STRONGER
WESTERLIES WILL HAVE SAGGED SOUTH A BIT MORE...INCREASING THE AMOUNT
OF DEEP LAYER SHEAR...WHICH WILL MAKE THE RISK OF LARGE HAIL A BIT
HIGHER OWING TO THE CHANCE OF GETTING AT LEAST WEAK SUPERCELL
STRUCTURES GOING.
LAST STOP IS WITH TEMPERATURES. OVERNIGHT...EXPECT CENTRAL MN TO
COOL A FEW DEGREES MORE THAN THEY DID LAST NIGHT AS THE PRESSURE
GRADIENT WEAKENS...ALLOWING FOR SOME RADIATIONAL COOLING TONIGHT.
STILL...WITH DEWPS AROUND 70...MOST PLACES SHOULD STILL STAY ABOVE
THAT MARK. FOR THE TWIN CITIES AND PLACES FARTHER SOUTH/EAST...WINDS
WILL REMAIN IN PLACE /THOUGH NOT AS STRONG AS LAST NIGHT/...WHICH
WILL KEEP SOME FORM OF MIXING GOING AND ONCE AGAIN MAKE IT A
STRUGGLE FOR A LOT OF PLACES TO DROP BELOW 80 WITHOUT THE HELP OF
RAIN.
FOR HIGHS TOMORROW...925-850 MB TEMPS ACTUALLY INCREASE A DEGREE OR
TWO AS COMPARED TO TODAY...WHICH WOULD THEORETICALLY MEAN WE COULD
GET A DEGREE OR TWO WARMER. HOWEVER...THERE IS THE POTENTIAL FOR A
BIG BUST WITH HIGHS TOMORROW DEPENDING ON WHAT HAPPENS WITH STORMS
TONIGHT. IF WE DO END UP SEEING FAIRLY WIDESPREAD AND ROBUST
CONVECTION OVERNIGHT...THIS WOULD LIKELY LEAVE BEHIND PLENTY OF
DEBRIS COLD COVER...PUTTING A DAMPER ON TEMPERATURES. THE HIRES NMM
EAST DOES EXACTLY THAT WITH CONVECTION OVERNIGHT. THE RESULTING
CLOUD COVER IT GENERATED FOR THE NEXT DAY RESULTED IN IT ONLY
GENERATING HIGHS IN THE MID/UPPER 80S. AT THE OTHER END OF THE
SCALE...A NIGHT OF LITTLE CONVECTION WILL RESULT IN ANOTHER DAY OF
LOTS OF SUN. IN THAT CASE...THEN HIGHS TOMORROW WOULD BE A DEGREE OR
TWO WARMER THAN TODAY...WITH HIGHS IN THE MID/UPPER 90S AND A FEW
100 DEGREE READINGS NOT OUT OF THE QUESTION IN WRN MN. AT ANY
RATE...DID NOT SEE ANYTHING GLARING CHANGE WITH THE TEMP FORECAST
TODAY THAT REQUIRED ANY CHANGES IN THE GOING HEAT HEADLINES.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 359 PM CDT SUN AUG 25 2013
LONG TERM TRENDS CONTINUE TO SHOW HOT AND HUMID CONDITIONS WILL
CONTINUE THROUGH AT LEAST TUESDAY. LOCATION OF FRONTAL BOUNDARY
MONDAY NIGHT WILL DETERMINE TO WHAT EXTENT/LOCATION CONVECTIVE ACTIVITY
WILL DEVELOP OVER THE CWA. VARIOUS DETERMINISTIC MODELS SHOW THIS
BOUNDARY LIFTING SLOWLY BACK NORTH MONDAY NIGHT AND INTO TUESDAY
AS WEAK COOL FRONT/SURFACE LOW MOVES THROUGH THE AREA. WILL
CONTINUE THE CHANCE POPS OVER THE NORTHEAST THIRD OF THE AREA FOR
TUESDAY...WHICH SHOULD EXIT THE CWA BY TUESDAY EVENING. EXPECT
TEMPERATURES TO RANGE IN THE MID/SOME UPPER 90S AND DEWPOINTS
POOLING AHEAD OF BOUNDARY INTO THE LOWER 70S. HEAT INDEX VALUES
WILL RANGE 100F TO 105F WITH THE CURRENT HEAT ADVISORY/WARNING
STILL LOOKING GOOD CONTINUING THROUGH TUESDAY.
SOME COOLING BEHIND THE FRONT LINGERING INTO FRIDAY...MAINLY OVER
THE EASTERN PORTION OF THE CWA. RIDGING ALOFT DEVELOPS THEREAFTER
WITH SURFACE FRONT MEANDERING OVER CENTRAL MINNESOTA AGAIN INTO
THE WEEKEND. THE 12Z ECMWF IS SLOWER BUILDING THE UPPER RIDGE TO
THE EAST...WITH THE MAIN SURGE COMING NEXT SUNDAY. THE GFS BUILDS
IN NORTH BY SATURDAY. WILL GO ALONG WITH PRESENT TREND OF BRINGING
THE 90S BACK INTO THE AREA FOR SATURDAY AND SUNDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 659 PM CDT SUN AUG 25 2013
TSRA DEVELOPMENT AT TAF ISSUANCE TIME WAS RATHER SPARCE AND
CONFINED TO NORTHERN MN. THINK ADDITIONAL DEVELOPMENT WILL TAKE
PLACE LATER THIS EVENING AND DRIFT SOUTH ACROSS ERN MN AND WRN WI
LATE TONIGHT. CONFIDENCE ON COVERAGE IS LOW AND CONDITIONAL ON
WHETHER THERE WILL BE ENOUGH FORCING. INSTABILITY IS RATHER
HIGH...SO STORMS MAY DEVELOP QUICK AND PRODUCE VERY HEAVY RAIN.
KEPT THE MENTION OUT OF WESTERN TAF SITES...BUT MAINTAINED PROB30
FOR MSP/STC AND VCTS FOR RNH/EAU. IT APPEARS MORE STORMS ACROSS
THE WRN DAKOTAS WILL WEAKEN BEFORE REACHING MN OVERNIGHT.
KMSP...PUSHED BACK THE TIMING OF STORMS SEVERAL HOURS TONIGHT DUE
TO LIMITED ACTIVITY ONGOING AND STRONG CAPPING. ANY TSRA WOULD BE
LATE TONIGHT AS OUTFLOWS FROM STORMS OVER NORTHERN MN DRIFT
SOUTHWARD.
/OUTLOOK FOR KMSP/
TUE...VFR. WIND SW 5-10 KT...BECOMING W/NW IN AFTERNOON.
WED...VFR. WIND NE 5 KT.
THU...VFR. ISOLD SHRA/TS POSSIBLE. WINDS SE 5 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ054>070-073>078-082>085-091>093.
HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ041>045-
047>053.
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ014>016-
023>028.
&&
$$
UPDATE...BORGHOFF
SYNOPSIS...MPG
SHORT TERM...MPG
LONG TERM...DWE
AVIATION...BORGHOFF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1256 PM CDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1230 PM CDT SAT AUG 24 2013
COUPLE OF CHANGES MADE TO THE FORECAST THIS MORNING. ONE...CLOUD
COVER IS MUCH LOWER THAN WHAT WAS EXPECTED EARLIER...WHICH HAS
ALLOWED TEMPS TO WARM A BIT MORE THAN ORIGINALLY FORECAST...
ESPECIALLY IN FAR WRN MN...WHERE PLACES LIKE MADISON AND APPLETON
ARE NOW EXPECTED TO WARM INTO THE MID 90S. AS A RESULT...STARTED
THE HEAT ADVISORY TODAY OUT IN A CHUNK OF COUNTIES OUT IN WRN MN
WHERE HEAT INDICES ARE EXPECTED TO CLIMB TO AROUND 100 THIS
AFTERNOON.
OTHER CHANGE HAS BEEN MADE WITH POPS. HAVE ALL BUT REMOVED ANY
POPS THROUGH THE REST OF TODAY AND TONIGHT. DESPITE THE PRESENCE
OF A 30-40 KT LLJ...VERY POOR MID LEVEL LAPSE RATES HAS MADE IT
VERY DIFFICULT FOR THIS LLJ TO GENERATE ANY PRECIP AND CERTAINLY
THE HRRR AND HOPWRF REFLECTIVITY FORECASTS SUPPORT A DRY FORECAST
THE REST OF THE DAY. THE ONLY OUTSIDE CHANCE THE MPX AREA WILL SEE
ADDITIONAL PRECIP WILL COME OVERNIGHT OVER CENTRAL MN DEPENDING
ON HOW FAR SOUTH ROBUST CONVECTION THAT WILL FIRE OVER NE NODAK
CAN BUILD OVERNIGHT. AT THIS POINT...ALL SIGNS POINT TO IT GOING
NORTH.
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 227 AM CDT SAT AUG 24 2013
TSRA FINALLY DEVELOPED ALONG THE LEADING EDGE OF THE MUCH
WARMER/HUMID AIR MASS ACROSS NE NEBRASKA/FAR SE SD SINCE 1 AM.
HOWEVER...THIS HAS NOT BEEN AS WIDESPREAD AS ANTICIPATED EARLIER
WHICH I HAVE SOME RESERVATION ON COVERAGE THIS MORNING IN
SOUTHERN/CENTRAL MN. BASED ON THE CURRENT MOVEMENT OF THE TSRA IN
SE SD...SCATTERED TSRA WILL BEGIN TO AFFECT SW MN BY 11Z.
TWO FACTORS WILL INFLUENCE THE TRAJECTORY OF THE CURRENT TSRA
ACTIVITY DURING THE MORNING. FIRST...THE VEERING OF THE LLJ
ASSOCIATED WITH DEVELOPMENT EARLIER TONIGHT...AND HOW IT WILL
TRANSLATE ACROSS SOUTHERN MN. SECOND...EASTERN MN IS NOT AS
UNSTABLE WITH THE EXCEPTION AT MID LEVELS WHICH INDICATES ELEVATED
ACTIVITY...AND NOT SFC BASED. A FEW WEAK REFLECTIVITY RETURNS
ACROSS SC MN ARE LIKELY THE LEADING EDGE OF THE MID LEVEL
INSTABILITY WHICH MAY ENHANCE CONVECTION ACROSS EASTERN MN DURING
THE MORNING HRS BEFORE THE CAP STRENGTHENS. THE BEST FORECAST THRU
NOON IS TO CONTINUE THE LOW POPS ACROSS MOST OF THE FA...WITH AN
ABRUPT DECREASE IN COVERAGE BY THE AFTN DUE TO THE INCREASING
CAP. ONLY THE FAR NE FA WILL HAVE ANY CHC OF TSRA/SHRA BY THE LATE
AFTN/EVENING HRS BASED ON 70H TEMPS. THE ONLY PROBLEM WITH THIS
MORNING FORECAST IS WHETHER THE LLJ STRENGTHENS TO THE POINT THAT
CONVECTION BECOMES MORE WIDESPREAD IN THE SW...WHICH MEANS LIKELY
POPS IN SW/SC MN.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 415 AM CDT SAT AUG 24 2013
CONTINUE TO FOCUS ON THE HEAT AND RELATED IMPACTS DURING THE LONG
TERM PORTION OF THE FORECAST. BY SUNDAY AFTERNOON...925-850MB
TEMPERATURES SOAR TO AROUND +28C AS THE THERMAL RIDGE NOSES INTO
THE AREA. THE 24.00Z NAM WANTED TO DEVELOP A LARGE AREA OF
SURFACE-BASED CONVECTION FROM CENTRAL MN INTO WEST CENTRAL WI ON
SUNDAY AFTERNOON AS DIURNAL WARMING IS MAXIMIZED...BUT THINK IT MAY BE
UNDERESTIMATING THE CAPPING. HAVE THEREFORE ONLY INCLUDED 20 POPS
FOR A GOOD PORTION OF THE AREA ON SUNDAY AFTERNOON...BUT EXPECT
SLIGHTLY BETTER CHANCES TO ARRIVE SUNDAY NIGHT INTO MONDAY AS A
35-45KT LOW LEVEL JET DEVELOPS AND ADVECTION PROCESSES ENSUE. THE
HIRES NMMEAST AND ARWEAST INDICATED SHOWERS AND THUNDERSTORMS
WILL BLOSSOM AROUND/AFTER 00Z MONDAY FROM EAST CENTRAL MN AND WEST
CENTRAL WI.
HIGH TEMPERATURES FROM SUNDAY THROUGH TUESDAY WILL MOSTLY RANGE
FROM 92 TO 97 DEGREES...WITH DEWPOINTS IN THE UPPER 60S TO LOWER
70S. THIS TRANSLATES TO HEAT INDICES FROM 95 TO 105 AND LOW TEMPS
NOT DECLINING LOWER THAN THE 70S. A WEAK FRONT IS STILL ON TRACK
TO PASS ACROSS ON TUESDAY...AND REDUCE TEMPERATURES FOR
WEDNESDAY...WHEN HIGHS WILL BE SLIGHTLY COOLER AND RANGE FROM 85
TO 90 DEGREES. A FEW SHOWERS AND THUNDERSTORMS MAY ACCOMPANY THE
FRONT ON TUESDAY AND TUESDAY EVENING...GENERALLY NORTH OF
INTERSTATE 94 WHERE THE CAP IS LESS STOUT.
TEMPERATURES BEGIN TO SNEAK BACK UP INTO THE UPPER 80S AND LOWER
90S FOR THURSDAY...WITH ABOVE NORMAL TEMPERATURES FROM 85 TO 95
DEGREES CONTINUING INTO NEXT WEEKEND AS THE MID LEVEL RIDGE HANGS
ON.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1230 PM CDT SAT AUG 24 2013
NO PRECIP IS ANTICIPATED THE REST OF THE PERIOD...WITH NOTHING
MORE THAN A FEW CU AND CIRRUS EXPECTED AS THE CAP CONTINUES TO
STRENGTHEN. WINDS HAVE COME UP AS ADVERTISED BY GUIDANCE AND GOING
TAFS HANDLED THE WINDS WELL SO MADE LITTLE CHANGES. OVERNIGHT...
GUSTS WILL FALL BACK...BUT NOT MUCH OF A DROP IN SUSTAINED WINDS
IS EXPECTED AS THE PRESSURE GRADIENT WILL REMAIN TIGHT. THESE
STRONG WINDS WILL ALSO KEEP THE BOUNDARY LAYER MIXED...
SIGNIFICANTLY REDUCING THE BR/HZ POTENTIAL SUNDAY MORNING.
KMSP...HIGH CONFIDENCE FORECAST ALL AROUND.
/OUTLOOK FOR KMSP/
MON...VFR...ISOLD TSRA POSSIBLE LATE. WIND S 5-10 KTS.
TUE...VFR. WIND SW 5-10 KT...BECOMING W/NW LATE.
WED...VFR. WIND NE 5 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ041>045-048>053-057>059-065>067-074>078-082>085-091>093.
HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ047-
054>056-064-073.
EXCESSIVE HEAT WARNING FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY
NIGHT FOR MNZ060>063-068>070.
WI...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ014>016-023>028.
&&
$$
UPDATE...MPG
SHORT TERM...JLT
LONG TERM...LS
AVIATION...MPG
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1101 PM EDT SUN AUG 25 2013
.SYNOPSIS...
AN APPROACHING FRONTAL SYSTEM WILL BRING SCATTERED SHOWERS AND
THUNDERSTORMS LATE TONIGHT AND MONDAY. DRY WEATHER IS FORECAST FOR
TUESDAY...BUT MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
TUESDAY NIGHT AND WEDNESDAY AS ANOTHER COLD FRONT MOVES THROUGH
THE REGION. AFTER THIS FRONT PASSES BY...FAIR WEATHER IS EXPECTED
FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
11 PM UPDATE...
EARLIER FORECASTER CAPTURED THE TIMING OF AN AREA OF RAIN AND
THUNDER QUITE WELL THAT IS NOW CROSSING LAKE ONTARIO. MAIN
ADJUSTMENT WAS TO SHIFT AXIS A BIT FARTHER WEST BASED ON RADAR THAN
WHAT THE HRRR AND NAM 12 IS SHOWING NOW. IN ADDITION INCREASED
POPS TO CAT GIVEN RADAR TRENDS AND INCREASED CONFIDENCE OF A 2 TO
4 HOUR WINDOW OF STEADY RAIN OVERNIGHT. STILL NOT OVERLY CONFIDENT
ON HOW FAR SOUTH IT MAKES IT TOWARD NORTHERN PA BECAUSE WE ARE
QUITE DRY...BUT CNY...FINGER LAKES...AND SOUTHERN TIER SEEM A SAFE
BET FOR NOW. AS THIS MCS SHIFTS SOUTHEAST AND DIES DOWN EARLY
MONDAY MORNING...WE MAY SEE A BREAK LATER MONDAY MORNING INTO THE
EARLY AFTERNOON. ON THE EDGE OF TONIGHT`S CONVECTION HOWEVER A NEW
AREA IS EXPECTED TO DEVELOP AGAIN MONDAY AFTERNOON/EVENING. SIGNS
STILL POINT TO THE POTENTIAL FOR LOCALLY HEAVY RAIN IN THE
NORTHWEST MOIST FLOW. THE PREVIOUS AFD IS BELOW...
UDPATED THE NEAR TEAM TO BRING POPS IN ERLR FROM THE MCS
THAT IS MOVING ACRS ONT AND QUE AND THE NERN GREAT LAKES. THE HRRR
HAS BEEN SHOWING THAT THIS PRECIP WILL GET INTO NC AND EC NY
BETWEEN 1Z AND 6Z WITH THE RAP NOW SPEEDING THE ARRIVAL UP TOO
OVER THE OTHER MODELS. SINCE THESE ARE RAPID UPDATE CYCLE MODELS
AND THE RADAR TRENDS ARE CLSR TO THESE MODELS I NOW BRING IN
PRECIP MUCH ERLR IN LINE WITH KBUF/S RECENT UPDATE. OTHERWISE...NO
OTHER CHANGES THRU MONDAY.
PREVIOUS DSCN BELOW...
VISIBLE SATL IMAGERY SHOWS SCT CUMULUS FORMING WITH INSOLATION.
SOME CIRRUS FROM AN UPSTREAM MCS OVER NRN AND CNTRL ONTARIO AND
THE UPPER LAKES WILL STREAM SOUTHEASTWARD FOR THE REST OF THE
AFTERNOON....THUS SKIES WILL BE PS TO MS. CANADIAN RADAR LOOP
SHOWS AN MCS WITH SHOWERS AND THUNDERSTORMS TRACKING SEWRD ACRS
GEORGIAN BAY AND TWD SERN ONTARIO INTO WRN QUEBEC. CONVECTION
ALLOWING MESOSCALE MODELS ...WRF-NMM, WRF-ARW AND HRRR ALL SHOW
THE SRN EDGE OF THE PRECIPITATION SHIELD WITH THIS MCS SKIRTING
ACRS NRN AND ERN NY TONIGHT WITH ELEVATED INSTABILITY REMAINING ON
THE BACK EDGE OF THE MCS AS IT WORKS SEWRD. THE MAIN QUESTION IS
TIMING. LATEST WRF-NMM AND WRF-ARW BOTH HAVE SHRA AND TSRA
ARRIVING AFTER 6Z...MAINLY 9-12Z ACRS NC NY SEWRD TO THE
CATSKILLS. THE HRRR ON THE OTHER HAND HAS THE PRECIP SHIELD AND
SOME TSRA ARRIVING MUCH ERLR...SPREADING FROM NC NY SOUTHWARD TO
THE CATSKILLS AND EVEN NE PA BETWEEN 1Z AND 6Z ABT 4-6 HOURS
SOONER. TTHE NAM...GFS AND CANADIAN ALL BRING SOME LIGHT PRECIP
INTO THESE AREAS LATE TONIGHT WITH THE RUC A LITTLE FASTER ON THE
ARRIVAL OF THE PRECIP. THUS THE HRRR AND THE RUC TO A LESSER
EXTENT AERE ON AN ISLAND BY THEMSELVES. HOWEVER...JUDGING BY
LATEST RADAR LOOP IT LOOKS LIKE THE HRRR HAS THE BEST HANDLE...BUT
THIS IS A MAJOR DEPARTURE FROM ERLR FCSTS AND ALL OTHER MODEL
GUIDC AND SOUNDINGS INDICATE THAT IT IS VERY DRY BELOW 10000 FEET.
SO FOR NOW WILL HAVE CHC POPS NRN AND ERN CWA INCREASING AFTR
6Z...BUT WILL RE-EVALUATE AND MAY HAVE TO BUMP UP POPS ERLR. I WUD
LIKE TO SEE RADAR TRENDS ON THE SRN EDGE OF THIS MCS AND IF THE
PRECIP IS REACHING THE GRND NEXT COUPLE HOURS.
FOR MONDAY...AN UPPER LEVEL WAVE WILL MOVE EASTWARD TWD NY AND PA
IN THE NW UPPER LEVEL FLO PATTERN. CONVECTION ALLOWING
MODELS...ESPECIALLY THE WRF-NMM, AND WRF-ARW AS WELL AS THE NAM
AND HIGHER RES CANADIAN ALL INDICATE SOME POTENTIAL FOR TRAINING
THUNDERSTORMS AS THE LL FLOW WILL BE W-NW AND FAIRLY ALIGNED WITH
THE UPPER LEVEL FLO. BOTH THE CANADIAN AND NAM HAVE A WELL
DEVELOPED JET ENTRANCE REGION CIRCULATION FOR OUR AREA WHEREAS THE
ERLR EURO AND 12Z GFS REALLY DON/T. MODEL CAPES ARE AVERAGING
ARND 1000 J/KG OR SO WITH MODEST SHEAR VALUES...GENERALLY 25 TO 30
KNOTS IN THE LOWEST 6 KM WITH MOST OF THE SHEAR ACTUALLY BETWEEN 0
AND 3 KM. I CAN EASILY SEE AN MCS EVOLVING OVER OUR REGION MON PM
AND...IN ITS WAKE SOME TRAINING STORMS WITH LOCALLY HEAVY RAINS.
FOR NOW...THINK LIKELY POPS ARE ON ORDER MON PM. THERE IS WAY TOO
MUCH UNCERTAINTY AS TO HEAVY RAINFALL POTENTIAL. NAM AND CMC GIVE
THE REGION A STRIPE OF 1-2 INCHES OF RAIN WHICH SHUDN/T BE MUCH OF
A PROBLEM AT ALL. HOWEVER WILL ALERT FUTURE SHIFTS FOR POTENTIAL
TO RAISE SITUATIONAL AWARENESS. AS FOR SEVERE POTENTIAL...THERE CUD BE
SOME LOCALLY DAMAGING WINDS...BUT AT THIS POINT IT LOOKS LIKE THE
CAPE AND SHEAR FALL SHORT OF WHAT WE WOULD EXPECT FOR AN OUTBREAK.
SPC CONCURS IN THEIR DAY 2 OUTLOOK.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
I KEPT TUESDAY DRY AS NY AND PA IS IN BETWEEN SYSTEMS WITH A SMALL
BUBBLE HIGH OVERHD. ALL SYNOPTIC MODELS INDICATE THAT THE MAJORITY
OF THE DAY IS DRY WITH JUST A FEW HUNDRENTHS POSSIBLE IN THE SW
AND FAR NE PART OF OUR CWA.
FOR WEDNESDAY...MODELS ARE IN AGREEMENT THAT ANOTHER MCS AND SHRT
WAVE WILL AFFECT THE REGION. MODEL TIMING AND PLACEMENT IS
UNCERTAIN THIS FAR OUT. SO I HAVE GENERIC CHC POPS FOR SHRA AND
TSRA TO COVER IN LINE WITH NEIGHBORING OFFICES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
NO MAJOR CHANGES TO THIS PART OF THE FORECAST. THE BROAD...AND
HOT LATE SEASON RIDGE OVER MUCH OF THE WESTERN AND CNTRL CONUS IS
STILL EXPECTED TO EXPAND INTO THE NORTHEAST BY THE END OF THE
PERIOD WITH REGIONAL HIGH TEMPERATURES EXPECTED TO RISE WELL INTO
THE MID 80S OVER NEXT WEEKEND.
THE ADVERTISED FRONTAL SYSTEM...POSSIBLY ACCOMPANIED BY A COMPLEX
SECONDARY LOW DEVELOPMENT ON THE BOUNDARY...IS STILL FORECAST TO
BE MOVING EAST OF THE AREA IN THE WEDNESDAY NIGHT-THURSDAY TIME
FRAME. THE FORECAST WILL STILL FEATURE DECREASING POPS WITH TIME
INTO THURSDAY...THEN WITH THE BROAD RIDGE IN PLACE THURSDAY NIGHT
AND NEXT WEEKEND LOOKS RAIN FREE AND WARMER AT THIS TIME.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
TRICKY FORECAST OVER THE NEXT 24 HOURS AS TIMING AND LOCATION OF
AREAS OF SHOWERS WILL BE VERY UNCERTAIN. AT THIS TIME OUR BEST
ESTIMATE IS THAT A FEW SHOWERS WILL TRACK SOUTH FROM ONTARIO
POSSIBLY REACHING SYR AND RME AFTER 03Z TONIGHT WITH LOCALIZED
MVFR CONDITIONS POSSIBLE. OTHERWISE VFR CONDITIONS WILL CONTINUE
ACROSS THE ENTIRE REGION INTO THE EARLY MORNING HOURS. SHOWERS MAY
SPREAD SOUTH ACROSS THE REST OF THE NY TAF SITES AFTER 06Z
BRINGING LOCALIZED MVFR CONDITIONS TO ITH/ELM/BGM... MEANWHILE VFR
CONDITIONS WILL CONTINUE AT AVP THROUGH THE NIGHT EXCEPT FOR BRIEF
MVFR VSBYS POSSIBLE IN LIGHT FOG AROUND DAYBREAK.
SCATTERED SHOWERS WITH LOCALIZED MVFR CONDITIONS WILL PERSIST
ACROSS NY STATE INTO THE MID-MORNING ON MONDAY THEN SCATTERED
THUNDERSTORMS WILL DEVELOP MONDAY AFTERNOON AGAIN WITH LOCALIZED
MVFR CONDITIONS POSSIBLE.
WINDS WILL BE LIGHT AND VARIABLE TONIGHT THAN SOUTHWEST AT 5 TO 15
KTS MONDAY.
OUTLOOK...
MON NGT...VFR. OCNL SHRA. CHC TSRA IN PM.
TUE...VFR. CHC SHRA/TSRA PM. LOCAL MVFR.
WED...VFR. SHRA/TSRA LIKELY. CHC MVFR.
THU...VFR.
FRI...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN/HEDEN
SHORT TERM...DJN
LONG TERM...JAB
AVIATION...JAB/MSE
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
746 PM EDT SUN AUG 25 2013
.SYNOPSIS...
AN APPROACHING FRONTAL SYSTEM WILL BRING SCATTERED SHOWERS AND
THUNDERSTORMS LATE TONIGHT AND MONDAY. DRY WEATHER IS FORECAST FOR
TUESDAY...BUT MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
TUESDAY NIGHT AND WEDNESDAY AS ANOTHER COLD FRONT MOVES THROUGH
THE REGION. AFTER THIS FRONT PASSES BY...FAIR WEATHER IS EXPECTED
FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
UDPATED THE NEAR TEAM TO BRING POPS IN ERLR FROM THE MCS THAT IS
MOVING ACRS ONT AND QUE AND THE NERN GREAT LAKES. THE HRRR HAS
BEEN SHOWING THAT THIS PRECIP WILL GET INTO NC AND EC NY BETWEEN
1Z AND 6Z WITH THE RAP NOW SPEEDING THE ARRIVAL UP TOO OVER THE
OTHER MODELS. SINCE THESE ARE RAPID UPDATE CYCLE MODELS AND THE
RADAR TRENDS ARE CLSR TO THESE MODELS I NOW BRING IN PRECIP MUCH
ERLR IN LINE WITH KBUF/S RECENT UPDATE. OTHERWISE...NO OTHER
CHANGES THRU MONDAY.
PREVIOUS DSCN BELOW...
VISIBLE SATL IMAGERY SHOWS SCT CUMULUS FORMING WITH INSOLATION.
SOME CIRRUS FROM AN UPSTREAM MCS OVER NRN AND CNTRL ONTARIO AND
THE UPPER LAKES WILL STREAM SOUTHEASTWARD FOR THE REST OF THE
AFTERNOON....THUS SKIES WILL BE PS TO MS. CANADIAN RADAR LOOP
SHOWS AN MCS WITH SHOWERS AND THUNDERSTORMS TRACKING SEWRD ACRS
GEORGIAN BAY AND TWD SERN ONTARIO INTO WRN QUEBEC. CONVECTION
ALLOWING MESOSCALE MODELS ...WRF-NMM, WRF-ARW AND HRRR ALL SHOW
THE SRN EDGE OF THE PRECIPITATION SHIELD WITH THIS MCS SKIRTING
ACRS NRN AND ERN NY TONIGHT WITH ELEVATED INSTABILITY REMAINING ON
THE BACK EDGE OF THE MCS AS IT WORKS SEWRD. THE MAIN QUESTION IS
TIMING. LATEST WRF-NMM AND WRF-ARW BOTH HAVE SHRA AND TSRA
ARRIVING AFTER 6Z...MAINLY 9-12Z ACRS NC NY SEWRD TO THE
CATSKILLS. THE HRRR ON THE OTHER HAND HAS THE PRECIP SHIELD AND
SOME TSRA ARRIVING MUCH ERLR...SPREADING FROM NC NY SOUTHWARD TO
THE CATSKILLS AND EVEN NE PA BETWEEN 1Z AND 6Z ABT 4-6 HOURS
SOONER. TTHE NAM...GFS AND CANADIAN ALL BRING SOME LIGHT PRECIP
INTO THESE AREAS LATE TONIGHT WITH THE RUC A LITTLE FASTER ON THE
ARRIVAL OF THE PRECIP. THUS THE HRRR AND THE RUC TO A LESSER
EXTENT AERE ON AN ISLAND BY THEMSELVES. HOWEVER...JUDGING BY
LATEST RADAR LOOP IT LOOKS LIKE THE HRRR HAS THE BEST HANDLE...BUT
THIS IS A MAJOR DEPARTURE FROM ERLR FCSTS AND ALL OTHER MODEL
GUIDC AND SOUNDINGS INDICATE THAT IT IS VERY DRY BELOW 10000 FEET.
SO FOR NOW WILL HAVE CHC POPS NRN AND ERN CWA INCREASING AFTR
6Z...BUT WILL RE-EVALUATE AND MAY HAVE TO BUMP UP POPS ERLR. I WUD
LIKE TO SEE RADAR TRENDS ON THE SRN EDGE OF THIS MCS AND IF THE
PRECIP IS REACHING THE GRND NEXT COUPLE HOURS.
FOR MONDAY...AN UPPER LEVEL WAVE WILL MOVE EASTWARD TWD NY AND PA
IN THE NW UPPER LEVEL FLO PATTERN. CONVECTION ALLOWING
MODELS...ESPECIALLY THE WRF-NMM, AND WRF-ARW AS WELL AS THE NAM
AND HIGHER RES CANADIAN ALL INDICATE SOME POTENTIAL FOR TRAINING
THUNDERSTORMS AS THE LL FLOW WILL BE W-NW AND FAIRLY ALIGNED WITH
THE UPPER LEVEL FLO. BOTH THE CANADIAN AND NAM HAVE A WELL
DEVELOPED JET ENTRANCE REGION CIRCULATION FOR OUR AREA WHEREAS THE
ERLR EURO AND 12Z GFS REALLY DON/T. MODEL CAPES ARE AVERAGING
ARND 1000 J/KG OR SO WITH MODEST SHEAR VALUES...GENERALLY 25 TO 30
KNOTS IN THE LOWEST 6 KM WITH MOST OF THE SHEAR ACTUALLY BETWEEN 0
AND 3 KM. I CAN EASILY SEE AN MCS EVOLVING OVER OUR REGION MON PM
AND...IN ITS WAKE SOME TRAINING STORMS WITH LOCALLY HEAVY RAINS.
FOR NOW...THINK LIKELY POPS ARE ON ORDER MON PM. THERE IS WAY TOO
MUCH UNCERTAINTY AS TO HEAVY RAINFALL POTENTIAL. NAM AND CMC GIVE
THE REGION A STRIPE OF 1-2 INCHES OF RAIN WHICH SHUDN/T BE MUCH OF
A PROBLEM AT ALL. HOWEVER WILL ALERT FUTURE SHIFTS FOR POTENTIAL
TO RAISE SITUATIONAL AWARENESS. AS FOR SEVERE POTENTIAL...THERE CUD BE
SOME LOCALLY DAMAGING WINDS...BUT AT THIS POINT IT LOOKS LIKE THE
CAPE AND SHEAR FALL SHORT OF WHAT WE WOULD EXPECT FOR AN OUTBREAK.
SPC CONCURS IN THEIR DAY 2 OUTLOOK.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
I KEPT TUESDAY DRY AS NY AND PA IS IN BETWEEN SYSTEMS WITH A SMALL
BUBBLE HIGH OVERHD. ALL SYNOPTIC MODELS INDICATE THAT THE MAJORITY
OF THE DAY IS DRY WITH JUST A FEW HUNDRENTHS POSSIBLE IN THE SW
AND FAR NE PART OF OUR CWA.
FOR WEDNESDAY...MODELS ARE IN AGREEMENT THAT ANOTHER MCS AND SHRT
WAVE WILL AFFECT THE REGION. MODEL TIMING AND PLACEMENT IS
UNCERTAIN THIS FAR OUT. SO I HAVE GENERIC CHC POPS FOR SHRA AND
TSRA TO COVER IN LINE WITH NEIGHBORING OFFICES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
NO MAJOR CHANGES TO THIS PART OF THE FORECAST. THE BROAD...AND
HOT LATE SEASON RIDGE OVER MUCH OF THE WESTERN AND CNTRL CONUS IS
STILL EXPECTED TO EXPAND INTO THE NORTHEAST BY THE END OF THE
PERIOD WITH REGIONAL HIGH TEMPERATURES EXPECTED TO RISE WELL INTO
THE MID 80S OVER NEXT WEEKEND.
THE ADVERTISED FRONTAL SYSTEM...POSSIBLY ACCOMPANIED BY A COMPLEX
SECONDARY LOW DEVELOPMENT ON THE BOUNDARY...IS STILL FORECAST TO
BE MOVING EAST OF THE AREA IN THE WEDNESDAY NIGHT-THURSDAY TIME
FRAME. THE FORECAST WILL STILL FEATURE DECREASING POPS WITH TIME
INTO THURSDAY...THEN WITH THE BROAD RIDGE IN PLACE THURSDAY NIGHT
AND NEXT WEEKEND LOOKS RAIN FREE AND WARMER AT THIS TIME.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
TRICKY FORECAST OVER THE NEXT 24 HOURS AS TIMING AND LOCATION OF
AREAS OF SHOWERS WILL BE VERY UNCERTAIN. AT THIS TIME OUR BEST
ESTIMATE IS THAT A FEW SHOWERS WILL TRACK SOUTH FROM ONTARIO
POSSIBLY REACHING SYR AND RME AFTER 03Z TONIGHT WITH LOCALIZED
MVFR CONDITIONS POSSIBLE. OTHERWISE VFR CONDITIONS WILL CONTINUE
ACROSS THE ENTIRE REGION INTO THE EARLY MORNING HOURS. SHOWERS MAY
SPREAD SOUTH ACROSS THE REST OF THE NY TAF SITES AFTER 06Z
BRINGING LOCALIZED MVFR CONDITIONS TO ITH/ELM/BGM... MEANWHILE VFR
CONDITIONS WILL CONTINUE AT AVP THROUGH THE NIGHT EXCEPT FOR BRIEF
MVFR VSBYS POSSIBLE IN LIGHT FOG AROUND DAYBREAK.
SCATTERED SHOWERS WITH LOCALIZED MVFR CONDITIONS WILL PERSIST
ACROSS NY STATE INTO THE MID-MORNING ON MONDAY THEN SCATTERED
THUNDERSTORMS WILL DEVELOP MONDAY AFTERNOON AGAIN WITH LOCALIZED
MVFR CONDITIONS POSSIBLE.
WINDS WILL BE LIGHT AND VARIABLE TONIGHT THAN SOUTHWEST AT 5 TO 15
KTS MONDAY.
OUTLOOK...
MON NGT...VFR. OCNL SHRA. CHC TSRA IN PM.
TUE...VFR. CHC SHRA/TSRA PM. LOCAL MVFR.
WED...VFR. SHRA/TSRA LIKELY. CHC MVFR.
THU...VFR.
FRI...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN
SHORT TERM...DJN
LONG TERM...JAB
AVIATION...JAB/MSE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1001 PM CDT SUN AUG 25 2013
.UPDATE...
ISSUED AT 1000 PM CDT SUN AUG 25 2013
GIVEN THE LATEST RADAR TRENDS AND INCOMING 00 UTC
GUIDANCE...REDUCE POPS TO JUST THE FAR SOUTH CENTRAL AND SOUTHERN
JAMES RIVER VALLEY FOR THE REMAINDER OF THE NIGHT. OTHERWISE...THE
REST OF THE FORECAST IS ON TRACK...WITH A MILD OVERNIGHT EXPECTED
WITH LOWS IN THE MID TO UPPER 60S FOR MOST LOCATIONS.
UPDATE ISSUED AT 752 PM CDT SUN AUG 25 2013
AS OF 0045 UTC...THUNDERSTORMS REMAIN FOCUSED FROM LEMMON TO
TIMBER LAKE SOUTH DAKOTA WHERE LOW LEVEL CONVERGENCE IS MAXIMIZED.
AGAIN...THE HRRR HAS HAD A GOOD HANDLE ON THE CONVECTION THIS
EVENING AND WILL FOLLOW ITS LATEST 23 UTC RUN FOR POPS...WHICH
GENERALLY REMAIN ALONG AND SOUTH OF I-94 WITH THE ONSET OF A MODEST
LOW LEVEL JET. THE OVERALL SEVERE THREAT IS MARGINAL ACROSS FAR
SOUTHERN NORTH DAKOTA AS THE BOUNDARY LAYER BEGINS TO STABILIZE.
HOWEVER...WILL HAVE TO MONITOR FOR STRONG WINDS GIVEN DOWNDRAFT
CAPE VALUES NEAR 1200 J/KG.
UPDATE ISSUED AT 520 PM CDT SUN AUG 25 2013
QUICK UPDATE TO INCREASE AND EXPAND POPS ACROSS WESTERN AND
CENTRAL NORTH DAKOTA FOR THE REMAINDER OF THE EVENING AND
OVERNIGHT. SURFACE BASED CONVECTION HAS BEEN INCREASING ACROSS
SOUTHWEST NORTH DAKOTA AND NORTHWEST SOUTH DAKOTA SINCE 2130 UTC
GIVEN THE LOSS OF CAPPING AND INCREASING UPPER LEVEL FORCING WITH
THE SHORTWAVE ENTERING WESTERN NORTH DAKOTA EVIDENT ON THE LATEST
WATER VAPOR IMAGERY. DEEP LAYER SHEAR ON THE ORDER OF 30-35 KTS
SUPPORTS THE POTENTIAL FOR PERHAPS A SUPERCELL OR TWO...WITH ML
CAPE VALUES AROUND 1500 J/KG. WHILE HIGH FREEZING LEVELS LIMIT THE
HAIL THREAT...DOWNDRAFT CAPE VALUES NEAR 1400 J/KG SUGGEST A
DAMAGING WIND THREAT WITH THE STRONGER STORMS. THE 18 UTC NAM AND
20 UTC HRRR ARE HANDLING THE CONVECTION WELL...WITH THE HRRR
SUGGESTING THE CONVECTION WILL PROPAGATE INTO BISMARCK AND MANDAN
LATER TONIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 317 PM CDT SUN AUG 25 2013
LATE SUNDAY AFTERNOON...SURFACE HIGH PRESSURE WAS ACROSS SOUTHERN
MANITOBA. A WEAK COLD FRONT WAS SLIDING SOUTH ACROSS CENTRAL NORTH
DAKOTA. ON SATELLITE...WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH
MOVE THROUGH WYOMING INTO CENTRAL MONTANA. THIS FEATURE IS
SUPPORTING CONVECTION ACROSS EASTERN MONTANA. SOME SHOWERS AND
ISOLATED THUNDERSTORMS SHOULD ENTER WEST CENTRAL AND NORTHWEST NORTH
DAKOTA LATE THIS AFTERNOON AND EVENING. THEN PROGRESSIVELY TRACKED
THE SLIGHT CHANCE TO CHANCE OF THUNDERSTORMS INTO WESTERN NORTH
DAKOTA OVERNIGHT AND INTO CENTRAL NORTH DAKOTA MONDAY. WITH THE
BASIC RIDGE PATTERN IN PLACE OVER THE CENTRAL AND NORTHERN
PLAINS...CONTINUED WARM TEMPERATURES EXPECTED ON MONDAY...HOWEVER
WITH COLD FRONT BRINGING A SLIGHT RELIEF WITH HIGHS IN THE UPPER 80S
NORTH TO LOWER 90S SOUTH ON MONDAY.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 317 PM CDT SUN AUG 25 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND
DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A
STRONG RIDGE OVER THE CENTRAL U.S. THAT RETROGRADES FROM THE
MISSOURI VALLEY WEST INTO THE SOUTHERN PLAINS THROUGH THE PERIOD.
NORTH DAKOTA WILL REMAIN NEAR THE APEX OF THE RIDGE THROUGH THE LONG
TERM FORECAST PERIOD...WHICH WILL CONTINUE TO INDICATE ABOVE AVERAGE
DAYTIME HIGH TEMPERATURES. SOUTHERN PORTIONS OF THE CWA COULD FLIRT
WITH HEAT ADVISORY CRITERIA LATER IN THE WEEK. IN ADDITION...ALMOST
DAILY THUNDERSTORM CHANCES CAN BE EXPECTED WITH HIGH CAPES EVERY DAY
BUT A STRONG CAP LIMITING CONVECTION.
THE DETERMINISTIC MODELS CONTINUE TO ADVERTISE A FEW...MORE
SIGNIFICANT...WAVES WORKING THROUGH THE MEAN RIDGE AND BRINGING
BETTER PRECIPITATION CHANCES. ON MONDAY AND INTO MONDAY NIGHT THE
ECMWF/GEM APPEAR STRONGER WITH A WAVE MOVING INTO NORTH DAKOTA AND
BRING QPF ACROSS THE NORTH. THE SOUTH MAY REMAIN CAPPED UNDER WARM
MID LEVEL TEMPERATURES.
WAVES CONTINUE TO WORK THROUGH THE MEAN RIDGE ON WEDNESDAY THROUGH
SATURDAY BUT TIMING AND PLACEMENT DIFFERENCES CONTINUE BETWEEN
MODELS AND MODEL RUNS. THEREFORE WILL CONTINUE TO UTILIZE A BLENDED
SOLUTION FOR PRECIPITATION. THIS WILL MEAN BETTER CHANCES WEDNESDAY
THROUGH THURSDAY AFTERNOON...THEN CHANCES ARE ON AND OFF FRIDAY
NIGHT THROUGH SUNDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 1000 PM CDT SUN AUG 25 2013
VFR CONDITIONS ARE FORECAST TONIGHT AND INTO TOMORROW ACROSS
WESTERN AND CENTRAL NORTH DAKOTA. THUNDERSTORMS ARE EXPECTED TO
DEVELOP AGAIN TOMORROW AFTERNOON ACROSS THE WEST AND PUSH EAST
THROUGH THE LATE AFTERNOON AND EARLY EVENING. A FEW OF THESE
STORMS COULD BE SEVERE.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...WAA
LONG TERM...JV
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
752 PM CDT SUN AUG 25 2013
.UPDATE...
ISSUED AT 752 PM CDT SUN AUG 25 2013
AS OF 0045 UTC...THUNDERSTORMS REMAIN FOCUSED FROM LEMMON TO
TIMBER LAKE SOUTH DAKOTA WHERE LOW LEVEL CONVERGENCE IS MAXIMIZED.
AGAIN...THE HRRR HAS HAD A GOOD HANDLE ON THE CONVECTION THIS
EVENING AND WILL FOLLOW ITS LATEST 23 UTC RUN FOR POPS...WHICH
GENERALLY REMAIN ALONG AND SOUTH OF I-94 WITH THE ONSET OF A MODEST
LOW LEVEL JET. THE OVERALL SEVERE THREAT IS MARGINAL ACROSS FAR
SOUTHERN NORTH DAKOTA AS THE BOUNDARY LAYER BEGINS TO STABILIZE.
HOWEVER...WILL HAVE TO MONITOR FOR STRONG WINDS GIVEN DOWNDRAFT
CAPE VALUES NEAR 1200 J/KG.
UPDATE ISSUED AT 520 PM CDT SUN AUG 25 2013
QUICK UPDATE TO INCREASE AND EXPAND POPS ACROSS WESTERN AND
CENTRAL NORTH DAKOTA FOR THE REMAINDER OF THE EVENING AND
OVERNIGHT. SURFACE BASED CONVECTION HAS BEEN INCREASING ACROSS
SOUTHWEST NORTH DAKOTA AND NORTHWEST SOUTH DAKOTA SINCE 2130 UTC
GIVEN THE LOSS OF CAPPING AND INCREASING UPPER LEVEL FORCING WITH
THE SHORTWAVE ENTERING WESTERN NORTH DAKOTA EVIDENT ON THE LATEST
WATER VAPOR IMAGERY. DEEP LAYER SHEAR ON THE ORDER OF 30-35 KTS
SUPPORTS THE POTENTIAL FOR PERHAPS A SUPERCELL OR TWO...WITH ML
CAPE VALUES AROUND 1500 J/KG. WHILE HIGH FREEZING LEVELS LIMIT THE
HAIL THREAT...DOWNDRAFT CAPE VALUES NEAR 1400 J/KG SUGGEST A
DAMAGING WIND THREAT WITH THE STRONGER STORMS. THE 18 UTC NAM AND
20 UTC HRRR ARE HANDLING THE CONVECTION WELL...WITH THE HRRR
SUGGESTING THE CONVECTION WILL PROPAGATE INTO BISMARCK AND MANDAN
LATER TONIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 317 PM CDT SUN AUG 25 2013
LATE SUNDAY AFTERNOON...SURFACE HIGH PRESSURE WAS ACROSS SOUTHERN
MANITOBA. A WEAK COLD FRONT WAS SLIDING SOUTH ACROSS CENTRAL NORTH
DAKOTA. ON SATELLITE...WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH
MOVE THROUGH WYOMING INTO CENTRAL MONTANA. THIS FEATURE IS
SUPPORTING CONVECTION ACROSS EASTERN MONTANA. SOME SHOWERS AND
ISOLATED THUNDERSTORMS SHOULD ENTER WEST CENTRAL AND NORTHWEST NORTH
DAKOTA LATE THIS AFTERNOON AND EVENING. THEN PROGRESSIVELY TRACKED
THE SLIGHT CHANCE TO CHANCE OF THUNDERSTORMS INTO WESTERN NORTH
DAKOTA OVERNIGHT AND INTO CENTRAL NORTH DAKOTA MONDAY. WITH THE
BASIC RIDGE PATTERN IN PLACE OVER THE CENTRAL AND NORTHERN
PLAINS...CONTINUED WARM TEMPERATURES EXPECTED ON MONDAY...HOWEVER
WITH COLD FRONT BRINGING A SLIGHT RELIEF WITH HIGHS IN THE UPPER 80S
NORTH TO LOWER 90S SOUTH ON MONDAY.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 317 PM CDT SUN AUG 25 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND
DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A
STRONG RIDGE OVER THE CENTRAL U.S. THAT RETROGRADES FROM THE
MISSOURI VALLEY WEST INTO THE SOUTHERN PLAINS THROUGH THE PERIOD.
NORTH DAKOTA WILL REMAIN NEAR THE APEX OF THE RIDGE THROUGH THE LONG
TERM FORECAST PERIOD...WHICH WILL CONTINUE TO INDICATE ABOVE AVERAGE
DAYTIME HIGH TEMPERATURES. SOUTHERN PORTIONS OF THE CWA COULD FLIRT
WITH HEAT ADVISORY CRITERIA LATER IN THE WEEK. IN ADDITION...ALMOST
DAILY THUNDERSTORM CHANCES CAN BE EXPECTED WITH HIGH CAPES EVERY DAY
BUT A STRONG CAP LIMITING CONVECTION.
THE DETERMINISTIC MODELS CONTINUE TO ADVERTISE A FEW...MORE
SIGNIFICANT...WAVES WORKING THROUGH THE MEAN RIDGE AND BRINGING
BETTER PRECIPITATION CHANCES. ON MONDAY AND INTO MONDAY NIGHT THE
ECMWF/GEM APPEAR STRONGER WITH A WAVE MOVING INTO NORTH DAKOTA AND
BRING QPF ACROSS THE NORTH. THE SOUTH MAY REMAIN CAPPED UNDER WARM
MID LEVEL TEMPERATURES.
WAVES CONTINUE TO WORK THROUGH THE MEAN RIDGE ON WEDNESDAY THROUGH
SATURDAY BUT TIMING AND PLACEMENT DIFFERENCES CONTINUE BETWEEN
MODELS AND MODEL RUNS. THEREFORE WILL CONTINUE TO UTILIZE A BLENDED
SOLUTION FOR PRECIPITATION. THIS WILL MEAN BETTER CHANCES WEDNESDAY
THROUGH THURSDAY AFTERNOON...THEN CHANCES ARE ON AND OFF FRIDAY
NIGHT THROUGH SUNDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 752 PM CDT SUN AUG 25 2013
ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS CENTRAL
NORTH DAKOTA THIS EVENING...WITH ANOTHER ROUND OF THUNDERSTORMS
EXPECTED TO DEVELOP AGAIN IN THE 16-18 UTC TIME FRAME MONDAY ACROSS
WESTERN AND CENTRAL NORTH DAKOTA...MOVING EAST INTO MONDAY EVENING.
THERE IS A SLIGHT CHANCE OF PATCHY FOG ACROSS THE AREA TONIGHT.
HOWEVER...GIVEN UNCERTAINTY WILL LEAVE FOG OUT OF THE TAFS FOR
NOW. VFR CONDITIONS OUTSIDE OF THUNDERSTORMS ARE FORECAST.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...WAA
LONG TERM...JV
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1238 PM CDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1230 PM CDT SAT AUG 24 2013
THIS UPDATE WILL FOCUS ON THE THUNDERSTORM AREA...WHICH IS NOW
ALONG AND NORTH OF LAKE SAKAKAWEA ASSOCIATED WITH THE WARM
FRONT/COLD FRONTAL SYSTEMS. UPPED THE POPS NORTH CENTRAL...WITH
LOWER POPS SOUTH AND WEST. TEMPERATURES AND WINDS LOOK GOOD SO
FAR.
UPDATE ISSUED AT 948 AM CDT SAT AUG 24 2013
SEVERAL AREAS OF ELEVATED THUNDERSTORMS FORMING ALONG THE WARM
FRONTAL BOUNDARY ACROSS WESTERN NORTH DAKOTA...AS WELL AS NORTHWEST
NORTH DAKOTA IN THE WARM ADVECTION REGION OF THE LOW. MODEL
FORECAST SOUNDINGS SHOW A WARM MID LEVEL SHOULD INHIBIT STRONG
CONVECTION...SURFACE BASED...THROUGH EARLY AFTERNOON. AREAS OF
THUNDERSTORMS SO FAR HAVE NOT BEEN WELL ORGANIZED...AND BELIEVE
WILL HAVE TO WAIT FOR COLD FRONT`S ARRIVAL LATER THIS AFTERNOON AND
EVENING FOR THE SEVERE POTENTIAL TO KICK IN. CURRENT THINKING IS
THE THUNDERSTORMS ACROSS THE WEST WILL TREND DOWN IN THE SHORT TERM
AS THE DIURNAL LOW LEVEL JET MIXES OUT. THEN WILL WAIT FOR LATE
AFTERNOON POTENTIAL. POOL OF MOIST AIR AND VERY WARM CONDITIONS
WILL PUSH THE HEAT INDEX INTO THE ADVISORY CATEGORY THIS AFTERNOON
SOUTH CENTRAL. CONTINUE THE HEAT ADVISORY. RAISED POPS WEST
CENTRAL AND NORTHWEST WHERE ONGOING CONVECTION IS
CURRENTLY...THEN TRENDED THE POPS BACK DOWN BY NOON.
UPDATE ISSUED AT 640 AM CDT SAT AUG 24 2013
SCATTERED THUNDERSTORMS FROM JUST WEST OF WILLISTON SOUTHEAST TO
NEAR KILLDEER CONTINUE TO TRACK NORTHEAST EARLY THIS MORNING.
UTILIZED THE 10 UTC HRRR FOR GUIDANCE TO EXTRAPOLATE CURRENT
CONVECTION INTO THE NORTH CENTRAL THROUGH THE MORNING HOURS. ALSO
ADJUSTED CLOUD COVER HIGHER IN THIS SAME AREA THROUGH THE MORNING.
OTHERWISE NO SIGNIFICANT CHANGES TO THE CURRENT FORECAST. STILL
LOOKS TO BE HOT AND HUMID THIS AFTERNOON OVER THE SOUTH CENTRAL
WITH HIGH TEMPERATURES NEAR 100 DEGREES. NO CHANGES TO HEAT
ADVISORY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 242 AM CDT SAT AUG 24 2013
HIGHLIGHTS AND CONCERNS THIS PERIOD DEAL WITH THE DECISION TO
ISSUE A HEAT ADVISORY FOR SOUTH CENTRAL NORTH DAKOTA SATURDAY
AFTERNOON INTO EARLY EVENING...AND POTENTIAL FOR SEVERE WEATHER
LATE THIS AFTERNOON THROUGH THE EVENING HOURS.
CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE AND AN ASSOCIATED WARM
FRONT OVER SOUTHEAST MONTANA. LATEST RADAR INDICATES AN AREA OF
SHOWERS AND THUNDERSTORMS IN SOUTHEAST MONTANA ARE MOVING
INTO SOUTHWEST NORTH DAKOTA THIS MORNING. THE 00Z MODEL DATA
SHIFTS THE WARM FRONT THROUGH SOUTH CENTRAL NORTH DAKOTA THIS
AFTERNOON AS LOW PRESSURE MOVES INTO SOUTHERN NORTH DAKOTA. A
COLD FRONT WILL THEN ENTER THE WEST BY MID AFTERNOON. WITH THE
WARM SECTOR OVERHEAD AND H85 TEMPS IN THE +27C TO +29C RANGE...A
WELL MIXED LAYER PER NAM/GFS SOUNDINGS WILL ALLOW FOR HIGH
TEMPERATURES TO REACH AROUND 100 DEGREES ACROSS MOST OF SOUTH
CENTRAL NORTH DAKOTA. THE RELATIVE HUMIDITY CROSS SECTIONS AND WATER
VAPOR LOOP SUGGESTS THAT SCT MID AND HIGH CLOUDS WILL BE THE MAIN
THEME TODAY WITHIN THE WARM SECTOR...AND THUS WENT ABOVE MODEL
GUIDANCE ON HIGH TEMPERATURES. A FEW DAYS AGO H85 TEMPS WERE
+26C WHEN BISMARCK REACHED 102 DEGREES. THINKING THAT TODAY WILL
BE SIMILAR. DEWPOINTS DO BEGIN TO FALL INTO THE LOWER 60S LATER
THIS AFTERNOON FROM BISMARCK TO LINTON...BUT ARE MAINTAINED IN THE
LOWER 70S IN THE JAMES RIVER VALLEY. HEAT INDICES ARE FORECAST TO
RANGE BETWEEN 100 AND 110 DEGREES WHICH COVERS ALL OF SOUTH
CENTRAL NORTH DAKOTA.
IT APPEARS THAT THE GREATEST THREAT FOR SEVERE WEATHER THIS
AFTERNOON AND EVENING WILL RESIDE IN THE WEST AND NORTH AS A
SHORTWAVE NOW LIFTING THROUGH NORTHERN UTAH MOVES INTO THE AREA
LATER TODAY. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN
THREAT. THE MID LEVEL CAP WILL BEGIN TO ERODE BETWEEN 21Z AND 00Z
SUNDAY ACROSS CENTRAL NORTH DAKOTA. THE HIGH RESOLUTION MODELS
CONTINUE TO OFFER DIFFERENT SOLUTIONS ON HOW THINGS WILL EVOLVE
LATER THIS AFTERNOON...SO SOME UNCERTAINTY REMAINS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 242 AM CDT SAT AUG 24 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND
DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A
STRONG RIDGE OVER THE CENTRAL U.S. ENSEMBLE SPREAD IS NEGLIGIBLE
THROUGH ALL BUT THE VERY END OF THE EXTENDED PERIOD AND
DETERMINISTIC LARGE SCALE DIFFERENCES ARE MINIMAL. WITH THAT
SAID...THERE ARE STILL ISSUES AMONG THE DETERMINISTIC MODELS IN
RESOLVING INDIVIDUAL IMPULSES TRANSLATING THROUGH THE BROAD UPPER
LEVEL FLOW FROM THE WESTERN U.S. INTO THE NORTHERN PLAINS.
THEREFORE THE FORECAST WILL FEATURE HOT DAYTIME HIGHS RANGING FROM
THE MID 80S NORTH TO THE MID 90S SOUTH AND MILD OVERNIGHT LOWS
MAINLY IN THE 60S...WITH A CONTINUED ALMOST DAILY CHANCE OF
THUNDERSTORMS. THERE IS REASONABLE AGREEMENT BETWEEN THE
DETERMINISTIC MODELS THAT MORE POTENT IMPULSES WILL TRAVERSE THE
AREA ON MONDAY AFTERNOON/EVENING AND AGAIN ON WEDNESDAY
AFTERNOON/EVENING. A MODEL BLEND WITH PERSISTENCE PRODUCES HIGHEST
POPS DURING THESE PERIODS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1230 PM CDT SAT AUG 24 2013
AT NOON CDT...A WARM FRONT EXTENDED INTO CENTRAL NORTH DAKOTA
WHILE A COLD FRONT WAS FOLLOWING INTO NORTHWEST NORTH DAKOTA. THE
FRONTAL SYSTEMS WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS
THIS AFTERNOON AND EARLY EVENING. MAIN IMPACT WILL BE FELT A
KMOT...WITH A SMALLER CHANCE AT KDIK-KBIS-KISN. AFTER 06Z
MAJORITY OF THUNDERSTORMS THREAT LIKELY EAST OF THE REGION. VFR
EXPECTED.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR
NDZ019>023-025-034>037-042-045>048-050-051.
&&
$$
UPDATE...WAA
SHORT TERM...KS
LONG TERM...TWH
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
959 AM CDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 948 AM CDT SAT AUG 24 2013
SEVERAL AREAS OF ELEVATED THUNDERSTORMS FORMING ALONG THE WARM
FRONTAL BOUNDARY ACROSS WESTERN NORTH DAKOTA...AS WELL AS NORTHWEST
NORTH DAKOTA IN THE WARM ADVECTION REGION OF THE LOW. MODEL
FORECAST SOUNDINGS SHOW A WARM MID LEVEL SHOULD INHIBIT STRONG
CONVECTION...SURFACE BASED...THROUGH EARLY AFTERNOON. AREAS OF
THUNDERSTORMS SO FAR HAVE NOT BEEN WELL ORGANIZED...AND BELIEVE
WILL HAVE TO WAIT FOR COLD FRONT`S ARRIVAL LATER THIS AFTERNOON AND
EVENING FOR THE SEVERE POTENTIAL TO KICK IN. CURRENT THINKING IS
THE THUNDERSTORMS ACROSS THE WEST WILL TREND DOWN IN THE SHORT TERM
AS THE DIURNAL LOW LEVEL JET MIXES OUT. THEN WILL WAIT FOR LATE
AFTERNOON POTENTIAL. POOL OF MOIST AIR AND VERY WARM CONDITIONS
WILL PUSH THE HEAT INDEX INTO THE ADVISORY CATEGORY THIS AFTERNOON
SOUTH CENTRAL. CONTINUE THE HEAT ADVISORY. RAISED POPS WEST
CENTRAL AND NORTHWEST WHERE ONGOING CONVECTION IS
CURRENTLY...THEN TRENDED THE POPS BACK DOWN BY NOON.
UPDATE ISSUED AT 640 AM CDT SAT AUG 24 2013
SCATTERED THUNDERSTORMS FROM JUST WEST OF WILLISTON SOUTHEAST TO
NEAR KILLDEER CONTINUE TO TRACK NORTHEAST EARLY THIS MORNING.
UTILIZED THE 10 UTC HRRR FOR GUIDANCE TO EXTRAPOLATE CURRENT
CONVECTION INTO THE NORTH CENTRAL THROUGH THE MORNING HOURS. ALSO
ADJUSTED CLOUD COVER HIGHER IN THIS SAME AREA THROUGH THE MORNING.
OTHERWISE NO SIGNIFICANT CHANGES TO THE CURRENT FORECAST. STILL
LOOKS TO BE HOT AND HUMID THIS AFTERNOON OVER THE SOUTH CENTRAL
WITH HIGH TEMPERATURES NEAR 100 DEGREES. NO CHANGES TO HEAT
ADVISORY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 242 AM CDT SAT AUG 24 2013
HIGHLIGHTS AND CONCERNS THIS PERIOD DEAL WITH THE DECISION TO
ISSUE A HEAT ADVISORY FOR SOUTH CENTRAL NORTH DAKOTA SATURDAY
AFTERNOON INTO EARLY EVENING...AND POTENTIAL FOR SEVERE WEATHER
LATE THIS AFTERNOON THROUGH THE EVENING HOURS.
CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE AND AN ASSOCIATED WARM
FRONT OVER SOUTHEAST MONTANA. LATEST RADAR INDICATES AN AREA OF
SHOWERS AND THUNDERSTORMS IN SOUTHEAST MONTANA ARE MOVING
INTO SOUTHWEST NORTH DAKOTA THIS MORNING. THE 00Z MODEL DATA
SHIFTS THE WARM FRONT THROUGH SOUTH CENTRAL NORTH DAKOTA THIS
AFTERNOON AS LOW PRESSURE MOVES INTO SOUTHERN NORTH DAKOTA. A
COLD FRONT WILL THEN ENTER THE WEST BY MID AFTERNOON. WITH THE
WARM SECTOR OVERHEAD AND H85 TEMPS IN THE +27C TO +29C RANGE...A
WELL MIXED LAYER PER NAM/GFS SOUNDINGS WILL ALLOW FOR HIGH
TEMPERATURES TO REACH AROUND 100 DEGREES ACROSS MOST OF SOUTH
CENTRAL NORTH DAKOTA. THE RELATIVE HUMIDITY CROSS SECTIONS AND WATER
VAPOR LOOP SUGGESTS THAT SCT MID AND HIGH CLOUDS WILL BE THE MAIN
THEME TODAY WITHIN THE WARM SECTOR...AND THUS WENT ABOVE MODEL
GUIDANCE ON HIGH TEMPERATURES. A FEW DAYS AGO H85 TEMPS WERE
+26C WHEN BISMARCK REACHED 102 DEGREES. THINKING THAT TODAY WILL
BE SIMILAR. DEWPOINTS DO BEGIN TO FALL INTO THE LOWER 60S LATER
THIS AFTERNOON FROM BISMARCK TO LINTON...BUT ARE MAINTAINED IN THE
LOWER 70S IN THE JAMES RIVER VALLEY. HEAT INDICES ARE FORECAST TO
RANGE BETWEEN 100 AND 110 DEGREES WHICH COVERS ALL OF SOUTH
CENTRAL NORTH DAKOTA.
IT APPEARS THAT THE GREATEST THREAT FOR SEVERE WEATHER THIS
AFTERNOON AND EVENING WILL RESIDE IN THE WEST AND NORTH AS A
SHORTWAVE NOW LIFTING THROUGH NORTHERN UTAH MOVES INTO THE AREA
LATER TODAY. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN
THREAT. THE MID LEVEL CAP WILL BEGIN TO ERODE BETWEEN 21Z AND 00Z
SUNDAY ACROSS CENTRAL NORTH DAKOTA. THE HIGH RESOLUTION MODELS
CONTINUE TO OFFER DIFFERENT SOLUTIONS ON HOW THINGS WILL EVOLVE
LATER THIS AFTERNOON...SO SOME UNCERTAINTY REMAINS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 242 AM CDT SAT AUG 24 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND
DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A
STRONG RIDGE OVER THE CENTRAL U.S. ENSEMBLE SPREAD IS NEGLIGIBLE
THROUGH ALL BUT THE VERY END OF THE EXTENDED PERIOD AND
DETERMINISTIC LARGE SCALE DIFFERENCES ARE MINIMAL. WITH THAT
SAID...THERE ARE STILL ISSUES AMONG THE DETERMINISTIC MODELS IN
RESOLVING INDIVIDUAL IMPULSES TRANSLATING THROUGH THE BROAD UPPER
LEVEL FLOW FROM THE WESTERN U.S. INTO THE NORTHERN PLAINS.
THEREFORE THE FORECAST WILL FEATURE HOT DAYTIME HIGHS RANGING FROM
THE MID 80S NORTH TO THE MID 90S SOUTH AND MILD OVERNIGHT LOWS
MAINLY IN THE 60S...WITH A CONTINUED ALMOST DAILY CHANCE OF
THUNDERSTORMS. THERE IS REASONABLE AGREEMENT BETWEEN THE
DETERMINISTIC MODELS THAT MORE POTENT IMPULSES WILL TRAVERSE THE
AREA ON MONDAY AFTERNOON/EVENING AND AGAIN ON WEDNESDAY
AFTERNOON/EVENING. A MODEL BLEND WITH PERSISTENCE PRODUCES HIGHEST
POPS DURING THESE PERIODS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 948 AM CDT SAT AUG 24 2013
AT 9 AM CDT...A WARM FRONT EXTENDED FROM LOW PRESSURE ACROSS
SOUTHERN SASKATCHEWAN INTO WESTERN NORTH DAKOTA. A COLD FRONT
EXTENDED FROM THE LOW ACROSS EASTERN MONTANA. THE WARM AND COLD
FRONTS WILL PROVIDE SEVERAL OPPORTUNITIES AND FOCUSING MECHANISMS
FOR THUNDERSTORMS. THE WARM AND COLD FRONTS WILL MOVE EAST TODAY.
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE IMPACTING KMOT-KDIK-
KBIS THROUGH 00Z. TIMING WILL BE CHALLENGING...RADAR EXTRAPOLATION
SUGGEST TSRA TO IMPACT KMOT BETWEEN 16-19Z...THEN KDIK- KBIS-KMOT
AGAIN AFTER 20Z WITH COLD FRONT PASSAGE. MAJORITY OF THUNDERSTORMS
SHOULD MOVE EAST OF THE REGION AFTER 06Z. VFR EXPECTED AT ALL TAF
SITES EXCEPT KJMS...WHERE MVFR COGS IN LOW LEVEL MOISTURE WILL
PREVAIL UNTIL 18Z..THE SHOULD BREAK OUT TO VFR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 8 PM
CDT /7 PM MDT/ THIS EVENING FOR NDZ019>023-025-034>037-042-
045>048-050-051.
&&
$$
UPDATE...WAA
SHORT TERM...KS
LONG TERM...TWH
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
640 AM CDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 640 AM CDT SAT AUG 24 2013
SCATTERED THUNDERSTORMS FROM JUST WEST OF WILLISTON SOUTHEAST TO
NEAR KILLDEER CONTINUE TO TRACK NORTHEAST EARLY THIS MORNING.
UTILIZED THE 10 UTC HRRR FOR GUIDANCE TO EXTRAPOLATE CURRENT
CONVECTION INTO THE NORTH CENTRAL THROUGH THE MORNING HOURS. ALSO
ADJUSTED CLOUD COVER HIGHER IN THIS SAME AREA THROUGH THE MORNING.
OTHERWISE NO SIGNIFICANT CHANGES TO THE CURRENT FORECAST. STILL
LOOKS TO BE HOT AND HUMID THIS AFTERNOON OVER THE SOUTH CENTRAL
WITH HIGH TEMPERATURES NEAR 100 DEGREES. NO CHANGES TO HEAT
ADVISORY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 242 AM CDT SAT AUG 24 2013
HIGHLIGHTS AND CONCERNS THIS PERIOD DEAL WITH THE DECISION TO
ISSUE A HEAT ADVISORY FOR SOUTH CENTRAL NORTH DAKOTA SATURDAY
AFTERNOON INTO EARLY EVENING...AND POTENTIAL FOR SEVERE WEATHER
LATE THIS AFTERNOON THROUGH THE EVENING HOURS.
CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE AND AN ASSOCIATED WARM
FRONT OVER SOUTHEAST MONTANA. LATEST RADAR INDICATES AN AREA OF
SHOWERS AND THUNDERSTORMS IN SOUTHEAST MONTANA ARE MOVING
INTO SOUTHWEST NORTH DAKOTA THIS MORNING. THE 00Z MODEL DATA
SHIFTS THE WARM FRONT THROUGH SOUTH CENTRAL NORTH DAKOTA THIS
AFTERNOON AS LOW PRESSURE MOVES INTO SOUTHERN NORTH DAKOTA. A
COLD FRONT WILL THEN ENTER THE WEST BY MID AFTERNOON. WITH THE
WARM SECTOR OVERHEAD AND H85 TEMPS IN THE +27C TO +29C RANGE...A
WELL MIXED LAYER PER NAM/GFS SOUNDINGS WILL ALLOW FOR HIGH
TEMPERATURES TO REACH AROUND 100 DEGREES ACROSS MOST OF SOUTH
CENTRAL NORTH DAKOTA. THE RELATIVE HUMIDITY CROSS SECTIONS AND WATER
VAPOR LOOP SUGGESTS THAT SCT MID AND HIGH CLOUDS WILL BE THE MAIN
THEME TODAY WITHIN THE WARM SECTOR...AND THUS WENT ABOVE MODEL
GUIDANCE ON HIGH TEMPERATURES. A FEW DAYS AGO H85 TEMPS WERE
+26C WHEN BISMARCK REACHED 102 DEGREES. THINKING THAT TODAY WILL
BE SIMILAR. DEWPOINTS DO BEGIN TO FALL INTO THE LOWER 60S LATER
THIS AFTERNOON FROM BISMARCK TO LINTON...BUT ARE MAINTAINED IN THE
LOWER 70S IN THE JAMES RIVER VALLEY. HEAT INDICES ARE FORECAST TO
RANGE BETWEEN 100 AND 110 DEGREES WHICH COVERS ALL OF SOUTH
CENTRAL NORTH DAKOTA.
IT APPEARS THAT THE GREATEST THREAT FOR SEVERE WEATHER THIS
AFTERNOON AND EVENING WILL RESIDE IN THE WEST AND NORTH AS A
SHORTWAVE NOW LIFTING THROUGH NORTHERN UTAH MOVES INTO THE AREA
LATER TODAY. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN
THREAT. THE MID LEVEL CAP WILL BEGIN TO ERODE BETWEEN 21Z AND 00Z
SUNDAY ACROSS CENTRAL NORTH DAKOTA. THE HIGH RESOLUTION MODELS
CONTINUE TO OFFER DIFFERENT SOLUTIONS ON HOW THINGS WILL EVOLVE
LATER THIS AFTERNOON...SO SOME UNCERTAINTY REMAINS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 242 AM CDT SAT AUG 24 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND
DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A
STRONG RIDGE OVER THE CENTRAL U.S. ENSEMBLE SPREAD IS NEGLIGIBLE
THROUGH ALL BUT THE VERY END OF THE EXTENDED PERIOD AND
DETERMINISTIC LARGE SCALE DIFFERENCES ARE MINIMAL. WITH THAT
SAID...THERE ARE STILL ISSUES AMONG THE DETERMINISTIC MODELS IN
RESOLVING INDIVIDUAL IMPULSES TRANSLATING THROUGH THE BROAD UPPER
LEVEL FLOW FROM THE WESTERN U.S. INTO THE NORTHERN PLAINS.
THEREFORE THE FORECAST WILL FEATURE HOT DAYTIME HIGHS RANGING FROM
THE MID 80S NORTH TO THE MID 90S SOUTH AND MILD OVERNIGHT LOWS
MAINLY IN THE 60S...WITH A CONTINUED ALMOST DAILY CHANCE OF
THUNDERSTORMS. THERE IS REASONABLE AGREEMENT BETWEEN THE
DETERMINISTIC MODELS THAT MORE POTENT IMPULSES WILL TRAVERSE THE
AREA ON MONDAY AFTERNOON/EVENING AND AGAIN ON WEDNESDAY
AFTERNOON/EVENING. A MODEL BLEND WITH PERSISTENCE PRODUCES HIGHEST
POPS DURING THESE PERIODS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 640 AM CDT SAT AUG 24 2013
THE LATEST RADAR IMAGERY SHOWS AN AREA OF SHOWERS AND THUNDERSTORMS
JUST WEST OF KDIK AND MOVING TOWARD KISN. WILL BEGIN THE FORECAST
WITH LIGHT THUNDERSTORMS AT KISN AND A VCTS AT KDIK. EXPECT THIS
AREA OF PRECIPITATION TO REACH KMOT BY 15Z. KBIS AND KJMS WILL REMAIN
VFR WITH A THREAT OF ISOLATED THUNDERSTORMS AT KBIS BY 00Z SUNDAY.
THERE IS A POTENTIAL FOR SOME SEVERE THUNDERSTORMS TODAY INTO EARLY
TONIGHT WITH LARGE HAIL AND DAMAGING WINDS. PATCHY FOG AND A BRIEF
REDUCTION TO MVFR CIGS/VSBYS IS POSSIBLE AT KJMS THROUGH 15Z
SATURDAY...OTHERWISE EXPECT VFR CIGS/VSBYS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 8 PM
CDT /7 PM MDT/ THIS EVENING FOR NDZ019>023-025-034>037-042-
045>048-050-051.
&&
$$
UPDATE...TWH
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1220 AM CDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1220 AM CDT SAT AUG 24 2013
LATEST SUITE OF SATELLITE IMAGERY AND LOCAL RADAR SUGGESTS THAT AN
AREA OF SHOWERS/THUNDERSTORMS IN SOUTHEAST MONTANA WILL CONTINUE
TO LIFT NORTHEAST OVERNIGHT...INTO SOUTHWEST AND WESTERN NORTH
DAKOTA. THIS IS IN LINE WITH THE LATEST HRRR MODEL. MODEL DATA
SUGGESTS THAT H85 WINDS ARE INCREASING NOW AND WILL MAINTAIN A
25KT TO 30KT PRESENCE THROUGH 09Z THEN TAPER OFF. THUS WILL KEEP
A CHC OF PRECIPITATION IN THE NORTH AHEAD OF THE WARM FRONT FOR
THE REST OF THE NIGHT. LITTLE CHANGES MADE FROM THE PREVIOUS
FORECAST.
LATER TODAY...WILL BE FOCUSING IN ON POSSIBLE HEAT ADVISORY FOR
SOUTH CENTRAL NORTH DAKOTA...WHICH IS FORECAST IN THE WARM SECTOR
WITH H85 TEMPS OF +27C TO +29C AND HIGHS AROUND 100 DEGREES.
UPDATE ISSUED AT 925 PM CDT FRI AUG 23 2013
LATE EVENING UPDATE FOR MINOR ADJUSTMENTS TO TEMPS AND POPS
OVERNIGHT. ONE ISOLATED CELL DEVELOPED NORTH OF GRASSY BUTTE THIS
EVENING BUT QUICKLY FELL APART DUE TO THE WARM AIR IN THE MID
LEVELS. HAVE MAINTAINED LOW POPS OVERNIGHT...ESPECIALLY
NORTH...BUT NOT OPTIMISTIC ABOUT ANYTHING MORE THAN ISOLATED
STORMS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 235 PM CDT FRI AUG 23 2013
FRIDAY AFTERNOON...A WARM FRONT ACROSS EASTERN MONTANA WAS POISED
TO MOVE EAST INTO WESTERN NORTH DAKOTA TONIGHT. THE FRONT WILL BE
THE FOCUS FOR SHOWERS AND THUNDERSTORMS. SO FAR TODAY...THE
ATMOSPHERE HAS BEEN TRANSITIONING FROM A COOLER AND DRYER AIR MASS
TO A WARMER AND MORE MOIST ONE. SOUNDING FORECASTS SHOW A STURDY
CAP IN PLACE ACROSS CENTRAL AND EAST. THIS WILL ERODE LATE THIS
AFTERNOON WEST. THE ADDITION OF MOISTURE HAS RESULTING IN GROWING
CU ACROSS THE EAST CENTRAL DESPITE THE CAP. DO NOT EXPECT THIS TO
AMOUNT TO MUCH THIS EVENING EAST. TONIGHT...THE WRF MODEL
GENERATES QUITE BIT OF CONVECTION ALONG AND AHEAD OF THE WARM
FRONT. THIS TOO WITH THE GFS. NAM A BIT DRIER. SATELLITE TRENDS SO
FAR SHOW CLOUDS AND THUNDERSTORMS IN CANADA SO BELIEVE THIS AREA
ALREADY NORTH OF THE CAP. KEPT THE HIGHEST POPS...40-50 NORTH AND
LOWEST SOUTH...GENERALLY FOLLOWING THE WARM FRONT AS IT PROGRESSES
EAST. THIS WILL BE FOLLOWED BY A COLD FRONT WEST LATE IN THE
AFTERNOON...WHICH WILL AGAIN BE THE FOCUS FOR SCATTERED
THUNDERSTORMS WEST SATURDAY AFTERNOON. MEANWHILE...THE WARM SECTOR
WILL BE OVER CENTRAL NORTH DAKOTA SATURDAY. HIGH WILL APPROACH 100
AND WITH HEAT INDEX VALUES NEAR 100 CONSIDERED A HEAT ADVISORY
FOR THE SOUTH CENTRAL COUNTIES ALONG THE SD BORDER.
HOWEVER...DEW POINTS ALREADY TRENDING DOWN SATURDAY SO THIS MAY
LIMIT THE HEAT INDEX BELOW 100. WILL HOLD OFF ON THE ADVISORY FOR
NOW.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 235 PM CDT FRI AUG 23 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH
FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN
TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS
WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S
TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED. WITH
DEWPOINTS GENERALLY IN THE MID 50S TO 60S EACH DAY...AFTERNOON HEAT
INDICES WILL LIKELY APPROACH 100 DEGREES SUNDAY AND MONDAY IN THE
SOUTH CENTRAL AND IN THE JAMES RIVER BASIN.
MODELS CONTINUE TO HAVE DIFFICULTY RESOLVING SHORTWAVES TRANSLATING
THROUGH THE BROAD SOUTHWEST FLOW FROM THE WESTERN UPPER LOW INTO THE
NORTHERN PLAINS AND SOUTHERN CANADA. THEREFORE A MODEL BLEND WAS
UTILIZED FOR POPS THROUGH THE PERIOD. MODELS ARE TRYING TO DEVELOP
CONVECTION ON SATURDAY NIGHT AS THERE WILL BE A SURFACE TROUGH
TRACKING SLOWLY EAST ACROSS THE AREA THAT IS PROGGED TO BE OVER
CENTRAL NORTH DAKOTA BY 00 UTC SUNDAY...WITH SHORTWAVE ENERGY MOVING
INTO WESTERN NORTH DAKOTA. WE WILL HAVE ABUNDANT CAPE OVER THE AREA
SATURDAY AFTERNOON BUT WILL LIKELY REMAIN CAPPED UNTIL SHORTWAVE
ENERGY ARRIVES LATE IN THE DAY. THUS THE BEST THUNDERSTORM CHANCES
ON SATURDAY ARE EXPECTED TO BE IN THE EVENING AND OVERNIGHT. SOME OF
THESE COULD BE STRONG TO SEVERE.
TODAY`S MODELS GIVE A BIT OF A REPRIEVE FOR CONVECTION CHANCES ON
SUNDAY...WITH NO MAIN UPPER LEVEL SHORTWAVES IN THE FLOW AND WEAK
SURFACE HIGH PRESSURE OVER THE REGION.
THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS
THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE
ENERGY CONTINUING TO TRAVERSE THE AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1220 AM CDT SAT AUG 24 2013
VFR CIGS EXPECTED...ALTHOUGH KJMS WILL LIKELY SEE PATCHY FOG
TOWARD 12Z AND POSSIBLE MVFR CIGS/VSBYS FOR A FEW HOURS. OTHERWISE
A VCTS IS FORECAST AT ALL AERODROMES WITH THE EXCEPTION OF KISN
AND KJMS. A COLD FRONT IS STILL ON TRACK TO SHIFT ACROSS THE
WESTERN AERODROMES BY AROUND 20Z-21Z SATURDAY...AND THE CENTRAL
TAF SITES BY AROUND 00Z SUNDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...WAA
LONG TERM...JV
AVIATION...KS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1140 PM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 1140 PM CDT FRI AUG 23 2013
NOT MUCH HAPPENING NOW PCPN WISE AND NOT LOOKING REALLY PROMISING
FOR MUCH FOR THE REMAINDER OF THE NIGHT. MODELS ARE REALLY
STRUGGLING TO MATCH UP WITH REALITY BUT THE GEM SEEMS TO BE DOING
BEST. RAP ALSO NOT DOING TOO BAD AND IT HAS LITTLE ELSE THRU THE
REST OF THE NIGHT. THEREFORE WILL CUT BACK TO ISOLATED
SHOWERS/TSTMS AND LET NEXT SHIFT WATCH.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 305 PM CDT FRI AUG 23 2013
FORECAST CHALLENGE FOR THE SHORT TERM WILL BE TEMPERATURES AND
POTENTIAL/PLACEMENT OF CONVECTION. A STATIONARY UPPER HIGH OVER
THE CENTRAL PLAINS IS YIELDING A SERIES OF MINOR SHORT WAVES
MOVING OUT OF THE SOUTHWEST CONUS AND INTO NORTHER TIER OF US.
MODELS ARE HAVING A DIFFICULT TIME WITH TIMING OF INDIVIDUAL WAVES
AS WELL AS PLACEMENT OF ASSOCIATED CONVECTION...THUS CONFIDENCE
FOR ANY SIGNIFICANT CONVECTION FOR ANY GIVEN AREA CONTINUES TO BE
LOW.
FOR TONIGHT...A WEAK VORT MAX OVER CNTRL MT WILL RIDE ALONG UPPER
RIDGE INTO NORTH CENTRAL ND/SOUTHERN MANITOBA TONIGHT. A WEAKER
VORT WILL MOVE ACROSS THE SOUTHERN VALLEY...BUT FEEL BEST CHANCE
FOR OVERNIGHT CONVECTION WILL BE ACROSS THE FAR NORTH WITH THE
COOLER H700 TEMPS. MODELS DO SHOW A SMALL AREA OF PRECIP
ASSOCIATED WITH SRN VORT/WARM ADVECTION DEVELOPING IN FAR SOUTHERN
VALLEY...WHERE BEST H850 MOISTURE TRANSPORT WILL HELP INCREASE
PWATS...HOWEVER STRONGEST LLJ FLOW WILL BE ACROSS SRN MN.
TOMORROW...WITH EXCEPTION OF 12Z NAM...MODELS MOVE FIRST WAVE OF
PRECIP OUT OF EASTERN ZONES BY MID MORNING WHILE THE NAM BRINGS A
SECOND WAVE INTO EASTERN ND BY MID DAY. CONSIDER THIS SOLUTION AN
OUTLIER AND WILL MAINTAIN A DRY FORECAST FOR THE VALLEY WEST DRG
THE DAY SATURDAY. WILL KEEP LOW CHANCE POPS IN THE EAST TO BETTER
BLEND WITH NEIGHBORS. CONTINUED WARM ADVECTION WILL BRING DAYTIME
HIGHS INTO THE UPPER 80S TO NEAR 90 IN THE SOUTH...WITH DEW POINTS
RISING INTO THE 60S...FOR A HOT AND HUMID DAY.
TOMORROW NIGHT...SFC TROUGH WILL MOVE INTO WRN ZONES WITH BEST
UPPER LEVEL ENERGY ACROSS NORTHERN ZONES AND SRN MB. WILL KEEP
SOUTHERN ZONES DRY AS STRONGER CAP SHOULD BE IN PLACE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 PM CDT FRI AUG 23 2013
SUNDAY AND MONDAY...WITH NO SIGNIFICANT CHANGE TO UPPER LEVEL
PATTERN...WILL CONTINUE TO SEE LOW CHANCES OF PRECIP ACROSS MAINLY
THE NORTHERN ZONES. TEMPS WILL RISE INTO 90S AND WITH JUICY
AIRMASS IN PLACE...HEAT ADVISORY CRITERIA IS POSSIBLE IN THE FAR
SOUTHERN VALLEY. BEYOND MONDAY...MODELS OVERALL IN REASONABLE AGREEMENT
THROUGH THE LONG RANGE. CENTER OF UPPER RIDGE TO REMAIN ACROSS
CENTRAL PLAINS THROUGH THE PERIOD. A COUPLE OF MORE SIGNIFICANT
WAVES WILL RIDE OVER THE RIDGE BRINGING MODEST RAIN CHANCES TO THE
REGION. FIRST WAVE LOOKS TO BE MONDAY NIGHT WITH ANOTHER ON
THURSDAY. TEMPERATURES TO REMAIN ABOVE TO WELL ABOVE AVERAGE
THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1140 PM CDT FRI AUG 23 2013
KEPT ANY MENTION OF PCPN OUT OF THE TAFS WITH LITTLE CONFIDENCE IN
ANYTHING HAPPENING. SOUTH WINDS SHOULD PICK UP AGAIN SAT MORNING
AND STAY UP THROUGH THE DAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...GODON
SHORT TERM...SPEICHER
LONG TERM...SPEICHER/VOELKER
AVIATION...GODON
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
300 PM CDT SAT AUG 24 2013
.DISCUSSION...
SEEING SOME SHOWER AND THUNDERSTORM DEVELOPMENT SO FAR THIS
AFTERNOON ACROSS MAINLY THE WESTERN PORTIONS OF THE FORECAST
AREA. A WEAK SEA BREEZE BOUNDARY IS WORKING ITS WAY INLAND...
AND THINK WE COULD SEE SOME ISOLATED STORMS DEVELOP ALONG THE
BOUNDARY WITH THE PEAK OF AFTERNOON HEATING. IN RESPONSE TO
RISING PRECIPITABLE WATER VALUES AND GREATER LIFT WITH THE
APPROACH OF THE NORTH CENTRAL GULF OF MEXICO DISTURBANCE...
THE AREA IS SILL ON TRACK FOR INCREASING RAIN CHANCES BEGINNING
LATER TONIGHT NEAR THE COAST AND ACROSS OFFSHORE WATERS...THEN
A LITTLE FURTHER INLAND AS THE DAY PROGRESSES. EXPECT TO SEE LESS
COVERAGE ACROSS OUR NORTHERN COUNTIES THAT WILL BE MORE UNDER THE
INFLUENCE OF UPPER LEVEL HIGH PRESSURE. RAIN CHANCES REMAIN IN
THE FORECAST (ESPECIALLY NEAR THE COAST AND OFFSHORE) SUNDAY
NIGHT THROUGH MONDAY AS THE GULF SYSTEM SLOWLY WORKS ITS WAY
WESTWARD ACROSS THE AREA. SOME LOCALLY HEAVY RAINFALL WILL BE
POSSIBLE BEFORE THIS EVENT COMES TO AN END...WITH SOME SPOTS
(AGAIN...ESPECIALLY NEAR THE COAST AND OFFSHORE) PROBABLY
RECEIVING SEVERAL INCHES. WILL CARRY LOWER RAIN CHANCES ON
TUESDAY...THEN HAVE NO RAIN IN THE FORECAST WEDNESDAY THROUGH
FRIDAY AS CENTRAL U.S. CENTERED UPPER LEVEL RIDGING BUILDS BACK
INTO THE AREA.
FYI - GALVESTON`S TEMPERATURE SENSOR HAS BEEN RUNNING SOME 5 TO 10
DEGREES TOO COOL. THE EQUIPMENT WILL BE CHECKED AS SOON AS POSSIBLE.
42
&&
.MARINE...
STILL SOME SHOWERS OUT IN THE SOUTHWEST COASTAL WATERS THIS
AFTERNOON. MORE SHOWERS ARE ON THEIR WAY THOUGH FROM THE EAST AS THE
TROPICAL WAVE APPROACHES SOUTHEAST TEXAS. COVERAGE WILL START TO
PICKUP TONIGHT INTO TOMORROW AND SHOULD CONTINUE THROUGH MONDAY.
LIGHT TO MODERATE EASTERLY WINDS WILL BECOME MORE SOUTHEASTERLY
SUNDAY AFTERNOON AS WAVE AXIS MOVES OFF TO THE WEST. HIGHER WINDS
AND SEAS WILL BE POSSIBLE IN THE STRONGER STORMS. 23
&&
.PREV DISCUSSION... /ISSUED 1232 PM CDT SAT AUG 24 2013/
DISCUSSION...
SEE AVIATION FOR 18Z TAF ISSUANCE.
AVIATION...
CURRENTLY SEEING SCATTERED SHOWERS FROM KCXO TO KUTS. THIS IS
FROM SOME SPEED CONVERGENCE OCCURRING AT 850MB. HRRR IS THE ONLY
MESOSCALE MODEL THAT IS CURRENTLY SHOWING THE ONGOING
PRECIPITATION AND APPEARS TO DOING A DESCENT JOB. GFS QPF FIELD
ALSO IS HINTING AT THIS. MORNING SOUNDINGS AT KLCH SHOWS DRIER AIR
IN PLACE AROUND 600MB. THIS DRY AIR APPEARS TO BE LIMITING SHOWER
DEVELOPMENT AS UPDRAFTS ARE HAVING TROUBLE PENETRATING THE
15000-16000 FT LEVEL. THIS SHOULD KEEP THUNDER ISOLATED.
MODELS ARE FORECASTING THE 850MB SPEED CONVERGENCE TO WASH OUT
LATER TODAY AND STAY MAINLY OFF TOWARDS THE NORTH OF KIAH. THERE
IS A SLIGHT CHANCE OF SOME AFTERNOON SHOWERS SOUTH THOUGH AS
CONVECTIVE TEMPERATURES ARE AROUND 90-92 DEGREES F. GIVEN LESS
SPEED CONVERGENCE TOWARDS OUR SOUTHERN TAF SITES HAVE LEFT MENTION
OF VICINITY SHOWERS OUT. KCXO AND KLBX AGAIN APPEAR TO HAVE A
CHANCE OF MVFR CONDITIONS THIS MORNING AS SOME VERY LIGHT FOG
COULD DEVELOP.
SUNDAY THE CHANCES OF RAIN INCREASE AS MOISTURE MOVES IN FROM THE
GULF. GFS IS MORE AGGRESSIVE BRINGING THE DEEPER TROPICAL MOISTURE
IN QUICKER THAT THE NAM. WILL LOOK FOR MORE MODEL CONSISTENCY ON
THIS TO HELP WITH THE TIMING AND LOCATION OF THE POSSIBLE RAIN ON
SUNDAY. 23
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 75 94 75 94 74 / 20 40 20 40 20
HOUSTON (IAH) 77 92 75 91 75 / 30 50 40 50 20
GALVESTON (GLS) 79 87 79 87 80 / 60 60 60 60 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...42
AVIATION/MARINE...23
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1232 PM CDT SAT AUG 24 2013
.DISCUSSION...
SEE AVIATION FOR 18Z TAF ISSUANCE.
&&
.AVIATION...
CURRENTLY SEEING SCATTERED SHOWERS FROM KCXO TO KUTS. THIS IS
FROM SOME SPEED CONVERGENCE OCCURRING AT 850MB. HRRR IS THE ONLY
MESOSCALE MODEL THAT IS CURRENTLY SHOWING THE ONGOING
PRECIPITATION AND APPEARS TO DOING A DESCENT JOB. GFS QPF FIELD
ALSO IS HINTING AT THIS. MORNING SOUNDINGS AT KLCH SHOWS DRIER AIR
IN PLACE AROUND 600MB. THIS DRY AIR APPEARS TO BE LIMITING SHOWER
DEVELOPMENT AS UPDRAFTS ARE HAVING TROUBLE PENETRATING THE
15000-16000 FT LEVEL. THIS SHOULD KEEP THUNDER ISOLATED.
MODELS ARE FORECASTING THE 850MB SPEED CONVERGENCE TO WASH OUT
LATER TODAY AND STAY MAINLY OFF TOWARDS THE NORTH OF KIAH. THERE
IS A SLIGHT CHANCE OF SOME AFTERNOON SHOWERS SOUTH THOUGH AS
CONVECTIVE TEMPERATURES ARE AROUND 90-92 DEGREES F. GIVEN LESS
SPEED CONVERGENCE TOWARDS OUR SOUTHERN TAF SITES HAVE LEFT MENTION
OF VICINITY SHOWERS OUT. KCXO AND KLBX AGAIN APPEAR TO HAVE A
CHANCE OF MVFR CONDITIONS THIS MORNING AS SOME VERY LIGHT FOG
COULD DEVELOP.
SUNDAY THE CHANCES OF RAIN INCREASE AS MOISTURE MOVES IN FROM THE
GULF. GFS IS MORE AGGRESSIVE BRINGING THE DEEPER TROPICAL MOISTURE
IN QUICKER THAT THE NAM. WILL LOOK FOR MORE MODEL CONSISTENCY ON
THIS TO HELP WITH THE TIMING AND LOCATION OF THE POSSIBLE RAIN ON
SUNDAY. 23
&&
.PREV DISCUSSION... /ISSUED 1023 AM CDT SAT AUG 24 2013/
DISCUSSION...
SCATTERED SHOWERS AND THUNDERSTORMS ARE CONFINED TO THE COASTAL WATERS
SO FAR THIS MORNING. WITH DAYTIME HEATING...EXPECT TO SEE SOME ISOLATED
TO WIDELY SCATTERED STORM DEVELOPMENT INLAND THIS AFTERNOON THROUGH
EARLY THIS EVENING. ALL SIGNS STILL POINT TOWARD BETTER RAIN CHANCES
BEGINNING EARLY TOMORROW MORNING NEAR THE COAST AND INLAND TOMORROW
AFTERNOON AS DEEPER TROPICAL MOISTURE EDGES INTO OUR AREA FROM THE
EAST. THIS TREND IS EXPECTED TO REPEAT AGAIN ON MONDAY. BASED ON THE
MOST RECENT MODEL DATA...STILL NOT REAL CONFIDENT ON HOW FAR INLAND
THE FUTURE ACTIVITY WILL GET. FOR NOW...SEE NO REASON FOR ANY SIGNIFICANT
CHANGES TO THE FORECAST WHICH HAS HIGHER POPS NEAR THE COAST AND OFFSHORE
FOR THE NEXT THREE DAYS. 42
PREV DISCUSSION... /ISSUED 423 AM CDT SAT AUG 24 2013/
DISCUSSION...
WEAK IMPULSE CURRENTLY MOVING ACROSS INLAND PARTS OF THE AREA IS
RESPONSIBLE FOR GENERATING SOME ISO/SCT PRECIP ACROSS NW PARTS OF
CWA. BOTH SYNOPTIC & MESOSCALE MODELS SHOW LIMITED COVERAGE OF
DAYTIME ACTIVITY ACROSS MOST OF THE AREA TODAY - PROBABLY DUE TO
SOME SUBSIDENCE IN ITS WAKE IN ADDITION TO SLIGHTLY LOWER PW`S
COMPARED TO YDAY. STILL ANTICIPATE SCT ACTIVITY NEAR THE COAST
THIS MORNING.
TROF SITUATED IN THE CNTL GULF WILL BEGIN ENTERING UPPER TX COASTAL
WATERS LATE TONIGHT & SUNDAY. EXPECT INCREASING SHRA/TSRA COVERAGE
OVERNIGHT IN THE GULF AS THIS OCCURS...THEN EVENTUALLY SPREADING
INLAND DURING THE DAY SUNDAY. PW`S CLIMB FROM AROUND 1.8" TODAY TO
2.1-2.4" SUN & MON ACROSS THE SRN HALF OF THE REGION. BEST OVERALL
COVERAGE WILL PROBABLY BE LATE SUN NIGHT THRU MON AFTN WITH HIGHER
QPFS CLOSER TO THE COAST. MODELS SUGGEST MORE PRECIP COVERAGE FURTHER
INLAND THAN I WOULD`VE SUSPECTED ESP CONSIDERING THE FCST STRENGTHENING
OF THE MID LEVEL RIDGE EXTENDING DOWN INTO THE REGION FROM THE PLAINS.
WILL HESITANTLY CONTINUE ADVERTISE CHANCE POPS ACROSS NRN AREAS FOR
NOW...BUT HAVE BEEN BURNED IN THESE SIMILAR PATTERNS IN PAST WITH
PRECIP HANGING CLOSER TO THE COAST.
RAIN CHANCES WILL BEGIN TO DIMINISH ON TUE AS THE TROF AXIS & ASSOCIATED
HIGHER MOISTURE LEVELS PUSH AWAY FROM SE TX. WED-FRI SHOULD BE MOSTLY
DRY & HOT AS MID LEVEL RIDGE REGAINS CONTROL. ECMWF STILL HINTING
AT THE POSSIBILITY OF ANOTHER WWD MOVING INVERTED TROF MOVING
ACROSS THE NRN GULF TOWARD TX NEXT WEEKEND. 47
MARINE...
PER LATEST RADAR LOOPS...QUITE A BIT OF MOISTURE/SCT SHRA OUT OVER
THE COASTAL WATERS THIS MORNING. SOME OF THE ACTIVITY IS MAKING IT
INTO THE COASTAL PARTS OF SE TX. WILL LIKELY SEE A REPEAT OF YEST-
ERDAY WITH THE SEABREEZE MOVEMENT/WIND DIRECTION FOR TODAY. MOTION
OF THE TROPICAL WAVE OVER THE NRN GULF CONTINUES TO THE WEST AS IT
SHOULD MOVE INTO THE AREA DURING THE LATTER PART OF THE DAY TOMOR-
ROW (SUN). THIS SHOULD INCREASE PCPN COVERAGE AND LIKELIHOOD OF AN
INCREASE OF WINDS/SEAS BRIEFLY IN/AROUND THESE STORMS. 41
AVIATION...
WHILE MODELS ARE INDICATING THAT THE BEST POPS WILL BE TOMORROW/SUN
WITH THE APPROACH/PASSAGE OF THE TROPICAL WAVE...WE COULD STILL SEE
SOME ISO/WIDELY SCT ACTIVITY TODAY. MOVEMENT OF THE SEABREEZE ALONG
WITH DAYTIME HEATING BEING THE MAIN FACTORS. WILL LIKELY DEBATE THE
RE-INCLUSION OF VCTS/VCSH FOR THE AFTN HOURS UNTIL THE LAST MINUTE.
OTHERWISE A MOSTLY VFR FCST SAVE FOR THE VERY BRIEF MVFR CIGS EARLY
THIS MORNING. 41
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 75 94 74 94 74 / 10 40 20 40 20
HOUSTON (IAH) 76 92 75 91 75 / 30 50 40 50 20
GALVESTON (GLS) 80 89 81 89 81 / 50 50 60 60 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
AVIATION/MARINE...23
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1215 PM CDT SAT AUG 24 2013
.AVIATION...
ISOLATED TO SCATTERED CONVECTION WILL BE POSSIBLE THIS
AFTERNOON...WITH THE BEST TIMING FOR AFFECTING ANY AIRPORT BEING FROM
19 TO 22 UTC PER LATEST HRRR MODEL. THUS...WILL NOT INCLUDE VCSH
OR VCTS IN THE 18 UTC TAFS...BUT WILL MONITOR RADAR TRENDS THIS
AFTERNOON AND UPDATE WHEN NECESSARY.
SKIES TO REMAIN VFR THROUGH THIS FORECAST AS EAST-SOUTHEAST LIGHT
WINDS PREVAIL. 75
&&
.UPDATE...
THE UPPER HIGH CENTER HAS MOVED FROM CENTRAL KANSAS ESE TOWARD THE
OZARKS THE PAST 24 HOURS. THE RAP/HRRR AND ARW MODELS HIGH-RES
MODELS HAVE REALLY OUTPERFORMED ALL THE OTHER MODELS REGARDING
DIURNAL CONVECTION THE PAST FEW DAYS WITH LITTLE TO NO SURFACE
FOCUS AND ONLY BENIGN FORCING ALOFT. A SLIGHTLY HIGHER MOISTURE
AXIS PER PWAT ANALYSIS WILL BE FOCUSED ACROSS THE FAR W/NW
COUNTIES THIS AFTERNOON ALONG WITH HIGHER RESULTANT SURFACE-
BASED INSTABILITY. A WEAK SURFACE LOW NEAR THESE AREAS ALONG WITH
BENIGN OLD OUTFLOW BOUNDARIES WILL LEND TO SOME SURFACE FOCUS AND
LEADS ME TO BELIEVE THAT COVERAGE WILL BE SLIGHTLY HIGHER THAN
THE REST OF THE CWA. THE HRRR/ARW MODELS CONCUR ON THIS SCENARIO.
A MINOR UPDATE WILL BE ISSUED TO SLIGHTLY RAISE POPS...ESPECIALLY
ACROSS THE FAR WEST-NORTHWEST COUNTIES THIS AFTERNOON/EARLY EVENING
WHERE POPS WERE RAISED TO 30 PERCENT FOR THIS AFTERNOON. ONLY SLIGHT
CHANCES ELSEWHERE. MOST OF THE ACTIVITY SHOULD WANE QUICKLY BY
SUNSET/AFTER. INSTABILITY WILL BE SUFFICIENT FOR A STRONG STORM OR
TWO WITH GUSTY WINDS...MORE FREQUENT LIGHTNING...AND BRIEF HEAVY
DOWNPOURS.
05/
&&
.PREV DISCUSSION... /ISSUED 322 AM CDT SAT AUG 24 2013/
A STAGNANT WEATHER PATTERN WILL PERSIST ACROSS THE REGION FOR THE
COMING WEEK AS AN AMPLIFIED RIDGE OF HIGH PRESSURE REMAINS
ANCHORED OVER THE CENTRAL PLAINS. THIS PATTERN WILL KEEP NORTH
TEXAS IN DEEP EASTERLY FLOW WHICH IN TURN WILL RESULT IN HOT AND
HUMID CONDITIONS THROUGH THE LAST WEEK OF AUGUST. EXPECT
TEMPERATURES TO REMAIN SLIGHTLY ABOVE SEASONAL NORMALS WITH HIGHS
GENERALLY IN THE UPPER 90S TO AROUND 100 AND LOWS IN THE 70S.
SOME VERY WEAK ENERGY WILL CONTINUE TO ROTATE AROUND THE SOUTHERN
PERIPHERY OF THE UPPER HIGH THROUGH EARLY NEXT WEEK. THE
COMBINATION OF WEAK LARGE SCALE LIFT WITH A MOIST AND UNSTABLE
ATMOSPHERE WILL RESULT IN ISOLATED TO WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS.
THUNDERSTORM CHANCES WILL DECREASE FROM NORTH TO SOUTH BEGINNING
EARLY NEXT WEEK AS THE UPPER HIGH BUILDS FURTHER SOUTH AND SHUNTS
THE DEEPER MOISTURE SOUTH OF THE REGION. ANY SHOWERS OR STORMS
THAT DO DEVELOP OVER THE NEXT COUPLE OF DAYS WILL BE EFFICIENT RAIN
PRODUCERS DUE TO THE DEEP MOISTURE IN PLACE. STORMS WILL ALSO
HAVE THE POTENTIAL TO PRODUCE MICROBURSTS DUE TO LARGE AFTERNOON
TEMPERATURE/DEW POINT SPREADS IN THE LOW LEVELS OF THE ATMOSPHERE.
ALTHOUGH A FEW AREAS MAY SEE BENEFICIAL RAINFALL OVER THE NEXT
COUPLE OF DAYS...MOST AREAS WILL NOT SEE ANY MEASURABLE RAINFALL
THROUGH THE COMING WEEK. UNFORTUNATELY...THERE ARE NO STRONG
INDICATIONS THAT THE UPPER RIDGE WILL BREAK DOWN OR MOVE AS WE
HEAD INTO EARLY SEPTEMBER. THE ONLY GLIMMER OF HOPE FOR INCREASING
RAIN CHANCES CAN BE SEEN IN THE 00Z ECMWF SOLUTION WHICH DOES
SHIFT THE UPPER RIDGE AXIS EAST OF THE MISSISSIPPI BY LABOR DAY.
79
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 100 78 99 78 98 / 20 10 10 10 10
WACO, TX 99 74 98 74 98 / 20 10 20 10 20
PARIS, TX 96 73 98 73 96 / 20 10 10 10 10
DENTON, TX 99 74 98 76 98 / 20 10 10 10 10
MCKINNEY, TX 99 73 97 74 96 / 20 10 10 10 10
DALLAS, TX 100 79 98 78 98 / 20 10 10 10 10
TERRELL, TX 99 75 98 75 97 / 20 10 10 10 10
CORSICANA, TX 99 75 98 74 97 / 20 10 20 10 20
TEMPLE, TX 98 72 98 73 97 / 20 10 30 20 20
MINERAL WELLS, TX 99 72 98 72 96 / 30 20 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS SPOKANE WA
502 PM PDT Sun Aug 25 2013
.SYNOPSIS...
The moist southwest flow the region has been in over the past week
or so will once again bring the chance for showers and
thunderstorms this afternoon into the overnight hours. As we move
into the work week precipitation chances will diminish with only the
higher terrain having a decent chance for activity. Another
weather system over the weekend will raise chances for widespread
precipitation once again.
&&
.DISCUSSION...
Tonight through Monday evening: The big picture includes a large
ridge of high pressure centered near Missouri and a large trof of
low pressure over the northeast Pacific. The semi-permanent trof
has been providing the Pacific Northwest with a busy
pattern...namely disturbances rotating around the base and
bringing enhanced chances of precipitation to the region. The most
recent upper level wave is evident on water vapor satellite
imagery moving inland near the California/Oregon coast. Clouds are
streaming ahead of this system throughout the inland northwest.
More importantly showers and thunderstorms are developing over
Oregon that will migrate toward the inland northwest this evening.
Overnight convection: isolated to scattered thunderstorms (some
severe this afternoon) in Oregon will eventually morph into a
large rain shield with embedded thunderstorms as it moves into
central and eastern Washington. The concern with our thermal
profile is the potential for a gust front along and ahead of the
line of storms. The latest runs of the HRRR support this with a
large band of rain and possible gust front heading north across
the state late this evening through the late night hours. We have
increased our chances of precipitation with this feature as well
as added wording about the potential for gusty winds. With each
run of the HRRR, the speeds of the storms are increasing so will
have to monitor close this evening and update as necessary. Still
some weak elevated instability remains on the back side of the
wave so a few showers still possible overnight.
Monday: Weather pattern quiets down for most of the region as the
next wave approaches Monday. The majority of the energy associated
with this wave will affect the northwest part of the state leaving
the inland northwest under partly cloudy skies with just a few
showers and thunderstorms possible in the afternoon and evening.
The exception will be near the Cascade crest where scattered
showers and isolated thunderstorms will again develop in the
afternoon and evening hours. The relatively quick storm motion
with these storms as well as tonights activity will minimize the
threat of flooding. Precipitable water values remain 120-180% of
normal for this time of the year so what isolated activity does
develop will be wet...minimizing the potential for dry lightning
strikes. /AB
Monday Night through Thursday Evening...The Inland Northwest will be
sandwiched between the trough of low pressure moving south toward
along the BC coast and a hefty ridge of high pressure anchored
over the central portion of the country. The tug-of-war will be
pulled to the slightly retrograding ridge for Tuesday and
especially Wednesday, and the temperature forecast shows this with
readings 5 to 8 degrees above normal by midweek. After that, a
disturbance rounding the trough will begin the breakdown of the
ridge for our region, and opening the door for the weekend system
to follow on its heels. Cooling temperatures closer to normal
Thursday also look likely as a front traverses eastern Washington
and the Idaho panhandle.
As far as precipitation goes, the Cascades should remain under the
influence of the trough and any minor shortwave that moves over
western Washington Tuesday and Wednesday. Precipitation chances
were not changed much from previous forecasts, which keeps slight
chances along and just east of the crest. Farther east, there may
be a few showers/thunderstorms that move north in the monsoonal
flow, although these chances look to be highest south and east of
the ID panhandle. As the shortwave on Thursday moves east,
slightly higher chances will exist over mainly the higher terrain,
although some of the precipitation may move into the valleys. ty
Thursday Night through Saturday Night: Starting the period we will
be in the never ending SW flow that will continue to bring chances
of showers and t-storms mainly in the higher elevations. The
system will send a final frontal wave through Friday afternoon into
the overnight that will bring a good chance for rain and
thunderstorms for the Cascades...the NE Mtns of WA and the ID
Panhandle. Models are finally showing the persistent trough and
associated low pressure system will eject into the region next
weekend. Where models lack consistency is the track and exact
timing of the system passage. The GFS would bring the system
onshore on the Oregon coast whereas the EC would bring it onshore
on the Washington coast. Regardless the region will see widespread
rain showers and the threat for thunderstorms. Models are showing
a pretty good amount of associated moisture with the system and
when it reaches the Cascades rain will be expected. With the
Cascades expected to receive a fair amount of rain we will have
to monitor the area for Hydrology concerns. With the exit of the
system comes more uncertainties...the EC quickly exits the system
Monday whereas the GFS has the system stall over the region
bringing a much more prolonged period of precipitation. With the
event still almost a week away we have time to refine the
details...but overall next weekend looks to be wet.
Concerning other aspects of the forecast...winds look to kick up
during the daytime periods but should not bring any problems.
Temperatures will be cooling down as our flow shifts to more
westerly rather than the southwest flow. As of right now
temperatures look to drop back into the 70s and 80s by the weekend.
/Fliehman
&&
.AVIATION...
00Z TAFS: A strong upper level disturbance will quickly push across
the region this evening. Satellite and radar observations show a
line of convection developing across eastern OR ahead of this wave
at 00Z. These thunderstorms have had a history of producing damaging
winds...heavy rain...and frequent cloud to ground lightning strikes.
The main aviation threat with these thunderstorms will be the
outflow winds. High resolution models have been consistent with a
strong gust front being produced out ahead of this convection and is
expected to push into KEAT...KMWH...KLWS and KPUW between 0200-0400Z
and later into KGEG...KSFF and KCOE between 0330-0500Z. Indications
are that this gust front could be capable of producing winds in
excess of 50 mph through this evening. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 79 58 83 60 88 / 50 20 10 10 10 10
Coeur d`Alene 57 79 55 83 57 88 / 50 20 10 10 10 10
Pullman 51 80 51 85 52 88 / 50 20 10 10 10 10
Lewiston 62 87 62 92 63 95 / 40 20 10 10 10 10
Colville 55 82 53 86 53 91 / 40 20 20 10 10 10
Sandpoint 53 77 50 81 50 86 / 50 20 20 10 10 10
Kellogg 56 78 56 83 56 86 / 50 20 20 10 10 10
Moses Lake 59 82 58 86 59 89 / 30 20 10 10 10 10
Wenatchee 62 81 62 85 64 88 / 40 20 10 10 10 10
Omak 60 82 58 85 59 89 / 30 30 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...&&
$$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
900 PM CDT SUN AUG 25 2013
.UPDATE...
CONDITIONS OVERNIGHT SHOULD STAY VERY QUIET FOR SOUTHERN
WISCONSIN. THE STORMS FIRING OVER NORTHERN MINNESOTA THIS EVENING
ARE SHOWING VERY LITTLE MOVEMENT TO THE SOUTH AT THIS TIME.
ADDITIONALLY...THIS ACTIVITY IS STRUGGLING TO GET GOING AND GET
ORGANIZED. THE MAIN CONCERN FROM THE PREVIOUS SHIFT WAS WHETHER
ANY CONVECTION TO THE NORTH WOULD DRIFT SOUTH INTO THE AREA LATER
TONIGHT. THE HRRR IS TRYING TO BRING SOME INTO OUR FAR NORTHERN
COUNTIES AROUND SUNRISE. BUT...IT/S OVERDOING THE CONVECTION
ALREADY THIS EVENING. IF WE DON/T GET MORE CONVECTION FIRING
OFF...THERE WON/T BE ANY COLD POOL DYNAMICS TO ALLOW THIS STUFF TO
PUSH SOUTH WITH ANY GREAT SPEED. IN THAT CASE...WE WILL STAY HIGH
AND DRY. THIS IS WHAT THE ECMWF/GEM SUGGEST. GIVEN TRENDS RIGHT
NOW...MY INCLINATION IS TO BELIEVE THE EC/GEM SOLUTIONS AND HAVE
THEREFORE BACKED OFF ON POPS ACROSS OUR NORTHERN/CENTRAL FORECAST
AREA. THERE WAS CONCERN THAT ANY STORM OUTFLOW WOULD PUSH THE
FRONT SOUTH INTO THE NORTHEAST CWA TOMORROW AND POSSIBLY COOL
TEMPS A BIT ACROSS THAT AREA. THIS IS LOOKING INCREASINGLY
UNLIKELY.
&&
.AVIATION/06Z TAFS/...
VFR THROUGH THE FORECAST PERIOD. THERE WAS CONCERN ABOUT
THUNDERSTORMS OVER MN AND NRN WI DROPPING SOUTH INTO THE AREA LATE
TONIGHT. THIS IS LOOKING INCREASINGLY UNLIKELY AS THE STORMS ARE
STRUGGLING TO GET GOING. NEXT CHANCE FOR STORMS WILL BE LATER
MONDAY NIGHT INTO TUESDAY.
&&
.PREV DISCUSSION... /ISSUED 331 PM CDT SUN AUG 25 2013/
SHORT TERM...
TONIGHT AND MONDAY...FORECAST CONFIDENCE MEDIUM
IT LOOKS PRETTY QUIET THROUGH THE EVENING HOURS...WITH A CHANCE FOR
SHOWERS AND STORMS AFTER MIDNIGHT AND INTO MONDAY. WILL BE WATCHING
THE POTENTIAL FOR AN UPSTREAM MCS TO MOVE INTO THE AREA
TONIGHT...THOUGH MODELS NOT ALL AGREEING ON THIS SCENARIO. CERTAINLY
PLENTY OF MOISTURE WITH PRECIPITABLE WATER VALUES GETTING UP TO
AROUND 2 INCHES. STILL SEEING DECENT ELEVATED INSTABILITY IN MODEL
SOUNDINGS...SO IF SOMETHING DOES GET GOING...SHOULD HAVE THE ABILITY
TO SURVIVE INTO THE FORECAST AREA.
WILL PROBABLY SEE A LULL IN THE SHOWER/STORM ACTIVITY MONDAY
MORNING...WITH MORE DEVELOPMENT POSSIBLE IN THE AFTERNOON. BEST
CHANCE FOR PRECIP TONIGHT AND TOMORROW WILL BE ACROSS THE NORTHEAST
HALF OF THE FORECAST AREA...WITH THE CONVECTION GENERALLY MOVING NW
TO SE UNDER NW FLOW. DID NOT GO HIGHER THAN CHANCE POPS...AS THERE
STILL REMAINS SOME MODEL DIFFERENCES...AND CONVECTION IS ALWAYS
TRICKY TO BEGIN WITH.
PRETTY CONFIDENT IN HIGH TEMPS ACROSS THE SOUTHWEST TOMORROW...BUT
MUCH LESS CERTAINTY IN THE NORTHEAST. ALL DEPENDS ON WHAT HAPPENS
WITH THE CONVECTION...AS STORMS MAY LAY DOWN A BOUNDARY THAT KEEPS
THE NORTHEAST COOLER THROUGH MUCH OF THE DAY. COULD SEE A FEW SPOTS
WITH A HEAT INDEX TOP OUT AROUND 100 TOMORROW...BUT DOES NOT SEEM
LIKE WIDESPREAD ENOUGH FOR A HEAT ADVISORY.
MONDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE MEDIUM
A WEAK...BUT ORGANIZED LOW PRESSURE AREA WILL MOVE FROM THE ERN DAKOTAS TO
NEAR KMSP BY 12Z TUE. THE NOSE OF THE LLJ AND A WEAK VORTICITY MAXIMUM
RIDING ALONG THE TOP OF THE RIDGE...WILL HELP INITIATE A MCS ALONG
THE W-E WARM FRONT WHICH WILL BE SITUATED ANYWHERE FROM CENTRAL
MN/WI TO NRN MN/WI. THE FARTHER SOUTH THE FRONT IS LOCATED THE
BETTER CHANCES OF THE ESEWD MOVING MCS WILL AFFECT THE NRN CWA.
THE LOCATION OF THE FRONT LATER ON MON AND MON NT WILL ALSO LIKELY
DEPEND ON HOW FAR SOUTH THE MCS TRAVERSES LATE TNT INTO MON AM.
OVERALL...BELIEVE THERE ARE GOOD CHANCES WE WILL SEE THE MCS AT LEAST AFFECT
THE NRN CWA LATE MON NT INTO TUE...THUS 50 POPS THERE WITH A DRY
FCST FOR THE FAR SRN CWA. THE WEAK LOW PRESSURE AREA WILL THEN
TRACK EWD ALONG THE FRONT OVER CENTRAL WI ON TUE. THIS WILL PUT A
STRONG LOW TO MID LEVEL THERMAL RIDGE OVER SRN WI WITH 925 MB
TEMPS AT 28-30C. EXPECT SFC TEMPS TO RECOVER QUICKLY FROM ANY
CLOUDS AND PCPN WITH THE BEST CHANCES OF HEAT INDICES OF 100F OR
GREATER OVER SOUTH CENTRAL WI. IF MCS AND CLOUDS AVOID ALL OF SRN
WI FOR TUE...THEN HEAT INDICES OVER 100F WOULD BE EXPECTED OVER
THE ENTIRE AREA. WILL CURRENTLY HOLD OFF ON HEAT ADVISORY FOR TUE
DUE TO CONVECTIVE UNCERTAINTY. THE WEAK COOL FROPA TO THEN OCCUR
TUE NT BUT NO DYNAMICS OR LLJ TO HELP INITIATE STORMS SO POPS
REMAIN LOW. HIGH PRESSURE TO THEN SETTLE OVER THE REGION FOR WED
AND THU BUT A VERY WARM AIRMASS CONTINUES TO PREVAIL WITH ONSHORE
FLOW KEEPING FAR ERN WI COOLER. MAXIMUM HEAT INDICES WILL BE IN
THE LOWER 90S WELL INLAND FOR BOTH DAYS.
LONG TERM...
FRIDAY THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM
SRN WI WILL REMAIN ON THE NRN PERIPHERY OF A BROAD UPPER RIDGE
THAT IS COVERING MUCH OF THE COUNTRY. SLY FLOW WILL RETURN DURING
THIS PERIOD WITH HOT TEMPERATURES AND HUMID CONDITIONS. HEAT
INDICES ARE TO REACH THE MID TO UPPER 90S BY AT LEAST SUNDAY.
CHANCES OF TSTORMS ARE FORECAST FOR THU NT INTO FRI DUE TO WEAK
SHORTWAVE TROUGHS RIDING ALONG THE TOP OF THE RIDGE.
AVIATION/00Z TAFS/...
QUIET WEATHER WILL PERSIST THROUGH THE DAYTIME HOURS AND INTO THIS
EVENING. STILL THINK THERE IS THE POTENTIAL FOR SHOWERS AND STORMS
LATER TONIGHT INTO MONDAY. THE BEST CHANCE CURRENTLY SEEMS TO BE
MAINLY NORTH OF A LONE ROCK TO KENOSHA LINE...BUT THAT IS CERTAINLY
SUBJECT TO CHANGE AS MODELS HAVE BEEN BACK AND FORTH WITH THIS SETUP.
MARINE...
WIND GUSTS ARE RIGHT NEAR SMALL CRAFT ADVISORY LEVELS THIS
AFTERNOON...SO WILL KEEP ADVISORY GOING. WINDS WILL BE LIGHTER THIS
EVENING...SO 01Z END TIME STILL LOOKS GOOD.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...DAVIS
TONIGHT/MONDAY AND AVIATION/MARINE...DDV
MONDAY NIGHT THROUGH SUNDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
610 PM CDT SUN AUG 25 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 346 PM CDT SUN AUG 25 2013
MAIN FORECAST CONCERNS ARE ON SEVERE THUNDERSTORM POTENTIAL TONIGHT
THROUGH TUESDAY AND HEAT INDEX VALUES.
LATEST SURFACE OBSERVATIONS PLACED A WARM FRONT EXTENDING FROM
SOUTHEAST NORTH DAKOTA THROUGH NORTHERN MINNESOTA...STRETCHING
EAST OVER SOUTHERN LAKE SUPERIOR. WATER VAPOR IMAGERY AND RAP 500 MB
ANALYSIS SHOWED HIGH PRESSURE CENTERED ALONG THE KANSAS/MISSOURI
BORDER WITH A FLATTENING RIDGE EXTENDING NORTH INTO THE UPPER
MISSISSIPPI RIVER VALLEY. A FEW SUBTLE SHORTWAVES NOTED...THE FIRST
WAS LOCATED OVER THE EASTERN DAKOTAS AND ANOTHER...SLIGHTLY STRONGER
WAVE...WAS MOVING INTO EASTERN MONTANA. THE WARM FRONT AND THESE TWO
WAVES WILL BE THE MAIN FEATURES TO KEEP A CLOSE EYE ON THROUGH
MONDAY MORNING. ALSO...A PLUME OF MONSOONAL MOISTURE WAS STREAMING
NORTHWARD THROUGH THE DESERT SOUTHWEST AND INTO WESTERN
NEBRASKA/SOUTH DAKOTA...HEADING EAST.
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE WARM FRONT THIS
EVENING...THEN MOVE SOUTHWARD OVERNIGHT. IT APPEARS THAT THE STORMS
WILL INITIATE OVER EAST CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN
THEN SHIFT SOUTHWARD WITH TIME DURING THE OVERNIGHT HOURS
POTENTIALLY IMPACTING AREAS NORTH OF INTERSTATE 90. CAPE VALUES
ARE RATHER IMPRESSIVE LATE THIS AFTERNOON OVER THESE AREAS...WITH
TEMPERATURES IN THE UPPER 90S AND DEWPOINTS IN THE LOWER 70S
PRODUCING 3500 TO 4000 J/KG OF SURFACE BASED CAPE. SHEAR ISN/T
OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR VALUES OF AROUND 30
KTS...MAINLY NORTH OF INTERSTATE 94. HOWEVER...THE SHEAR IS FOCUSED
IN THE 0-3 KM LAYER WHICH WOULD FAVOR THE POTENTIAL FOR LINEAR STORM
STRUCTURES WITH DAMAGING WINDS. THE HIGH INSTABILITY OVER THE AREA
SHOULD OVERCOME THE LACK OF STRONG SHEAR...LEADING TO THE POTENTIAL
FOR SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS. STRONG
850 MB MOISTURE TRANSPORT FOCUSES INTO THE WARM FRONT TONIGHT WHICH
COULD POTENTIALLY LEAD TO REPEATED ROUNDS OF THUNDERSTORMS ALONG IT.
PRECIPITABLE WATER VALUES INCREASE TO 2.0 TO 2.3 INCHES
TONIGHT...WHICH IS AROUND 230 PERCENT OF NORMAL. ALSO...WARM CLOUD
DEPTHS INCREASE TO AROUND 4.7 KM. ANY THUNDERSTORMS THAT DEVELOP IN
THIS AIRMASS WILL BE VERY EFFICIENT RAIN PRODUCERS. THESE FACTORS
COULD LEAD TO FLASH FLOODING OVER PORTIONS OF NORTHERN AND NORTH
CENTRAL WISCONSIN TONIGHT INTO EARLY MONDAY MORNING. CONFIDENCE ON
SEVERE THUNDERSTORM POTENTIAL IS HIGHEST NORTH AND EAST OF
INTERSTATE 94 TONIGHT. A STRONG CAP ALONG AND SOUTH OF THESE AREAS
SHOULD LIMIT HOW FAR SOUTH CONVECTION CAN BUILD. CANNOT RULE OUT THE
STORMS MAKING IT TO THE INTERSTATE 90 CORRIDOR BUT THEY SHOULD
QUICKLY DISSIPATE IF THEY MAKE IT ANY FURTHER SOUTH AND ENCOUNTER
THE STRONG CAP.
SHOWERS AND STORMS SHOULD QUICKLY TAPER OFF EARLY MONDAY MORNING AS
MOISTURE TRANSPORT WEAKENS. DEPENDING ON HOW THE OVERNIGHT
CONVECTION PLAYS OUT...THE WARM FRONT LOOKS TO BE ORIENTED JUST
NORTH OF THE INTERSTATE 94 CORRIDOR BY LATE MONDAY MORNING INTO
MONDAY AFTERNOON. MLCAPE VALUES INCREASE INTO THE 2000 TO 3500 J/KG
RANGE ALONG THE FRONT BY MID AFTERNOON ON MONDAY. 0-6 KM BULK SHEAR
VALUES HOVER AROUND 30 KTS OVER MUCH OF NORTHERN AND CENTRAL
WISCONSIN MONDAY AFTERNOON INTO MONDAY EVENING WHICH WOULD FAVOR
SEVERE MULTICELL STORMS. WITH THE HIGH CAPE VALUES NEAR THE WARM
FRONT...CANNOT RULE OUT A FEW SUPERCELL STRUCTURES ESPECIALLY OVER
NORTHWEST INTO NORTH CENTRAL WISCONSIN. ALSO FORECAST MODELS SUGGEST
THERE COULD BE JUST ENOUGH 0-1 KM SHEAR TO SUPPORT AN ISOLATED
TORNADO OR TWO NEAR THE WARM FRONT. OTHERWISE...THE STORMS WILL BE
CAPABLE OF PRODUCING LARGE HAIL...DAMAGING WINDS...AND HEAVY
RAINFALL. THE SHOWERS AND STORMS WILL CONTINUE INTO MONDAY NIGHT
WITH THE HIGHEST CHANCES MAINLY ALONG AND NORTHEAST OF INTERSTATE
94.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 346 PM CDT SUN AUG 25 2013
SHOWERS AND STORMS WILL BE ONGOING TUESDAY MORNING...MAINLY ALONG
AND EAST OF THE MISSISSIPPI RIVER. A WEAK COLD FRONT IS EXPECTED TO
SWEEP ACROSS THE REGION TUESDAY AFTERNOON. A FEW SHOWERS AND STORMS
CANNOT BE RULED OUT ALONG THE FRONT TUESDAY AFTERNOON INTO TUESDAY
EVENING...BUT IT APPEARS A CAP WILL HOLD STRONG FOR AREAS WEST OF
THE MISSISSIPPI RIVER...WITH A CHANCE OF SHOWERS AND STORMS OVER
MUCH OF WESTERN INTO CENTRAL WISCONSIN. 925MB TEMPERATURES COOL INTO
THE 22 TO 25 C RANGE IN THE WAKE OF THE FRONT. SO WE SHOULD SEE A
VERY SMALL RELIEF FROM THE HEAT WITH HEAT INDEX VALUES FALLING INTO
THE MID TO UPPER 90S. SURFACE HIGH PRESSURE SETTLES OVERHEAD ON
THURSDAY BRINGING SOME SLIGHTLY COOLER AIR WITH IT...WITH 925MB
TEMPERATURES FALLING TO AROUND 23 C...PRODUCING HIGHS IN THE UPPER
80S TO AROUND 90. THE HIGH SLIDES OFF TO THE EAST ON FRIDAY AS A
WARM FRONT PUSHES EAST OUT OF THE NORTHERN/CENTRAL PLAINS. WEAK
SHORTWAVES ARE EXPECTED TO INTERACT WITH THE FRONT BRINGING CHANCES
FOR SHOWERS AND STORMS TO THE AREA FROM THURSDAY AFTERNOON THROUGH
FRIDAY NIGHT. MODEL SOLUTIONS START TO DIVERGE SATURDAY INTO SUNDAY
ON TIMING OF THESE SHORTWAVES SO CONFIDENCE LOW ON PRECIPITATION
CHANCES SATURDAY INTO SUNDAY. TEMPERATURES ARE EXPECTED TO WARM
SLIGHTLY FOR THE WEEKEND WITH HIGHS CLIMBING INTO THE UPPER 80S TO
LOWER 90S...DEPENDING ON TIMING OF THE SHORTWAVES AND ANY SHOWERS
AND STORM ASSOCIATED WITH THEM. 850MB TEMPERATURE STANDARDIZED
ANOMALIES HOVER AROUND PLUS 2 THIS WEEKEND THROUGH EARLY NEXT WEEK
SO WILL HAVE TO KEEP A CLOSE WATCH ON THE POTENTIAL FOR HEAT
HEADLINES WITH THE POSSIBILITY OF SEEING NEAR RECORD HEAT FOR THESE
DATES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 610 PM CDT SUN AUG 25 2013
MODELS IN RELATIVELY GOOD AGREEMENT WITH FIRING A LINE/AREA OF
SHRA/TS ACROSS NORTHERN MN/WI TONIGHT...POWERED BY LOW LEVEL
MOISTURE TRANSPORT/INSTABILITY/SFC BOUNDARY. TRENDS THEN TAKE IT
SOUTH...BUT MODELS VARY IN HOW FAR SOUTH/WEST THE PCPN WILL REACH.
THE NAM12 IS THE MOST AGGRESSIVE...WHILE LATEST HRRR KEEPS THAT PCPN
TO THE NORTH...BUT SUGGESTS A CHANCE FOR SOME SHRA/TS TOWARD 12Z.
THIS ACTIVITY WOULD BE ASSOCIATED WITH A SHORTWAVE TROUGH TRAIPSING
ACROSS THE NORTHERN PLAINS. CONFIDENT THAT PRECIPITATION WILL GET
GOING ACROSS NORTHERN PARTS OF THE REGION TONIGHT...NOT SO MUCH ON
THE SOUTHERN REACH OF IT. WOULD LIKELY BE ON A DIMINISHING TREND AS
IT APPROACHES...WITH THE LOW LEVEL JET/MOISTURE TRANSPORT WANING
TOWARD 12Z. WILL HOLD ONTO THE VCTS FOR THE MOMENT...BUT MAY NEED TO
REMOVE IT IF TRENDS MAKE IT MOVE EVIDENT THE SHRA/TS WON/T SINK THIS
FAR SOUTH. SATURATION ISN/T OVERLY DEEP EITHER...SO IF THE PCPN
WOULD MAKE IT TO THE TAF SITES...CIGS WOULD LIKELY STAY VFR...MOSTLY
IN A 8-12 KFT RANGE.
THE SFC FRONT SHOULD NUDGE BACK NORTH ON MONDAY...AND WILL SERVE AS
A FOCUS FOR MORE SHRA/TS MONDAY AFTERNOON-NIGHT. HERE AGAIN...THERE
COULD BE A THREAT FOR PCPN AT THE TAF SITES...DEPENDING ON WHERE THE
BOUNDARY LAYS UP AND THE TRACK OF AN UPPER LEVEL DISTURBANCE.
TRENDS FAVOR KEEPING THE SHRA/TS TO THE NORTH FOR NOW.
&&
.CLIMATE...
ISSUED AT 346 PM CDT SUN AUG 25 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
032>034-041>044-053>055-061.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ079-
086>088-094>096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....RIECK
CLIMATE......WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1244 PM CDT SAT AUG 24 2013
.UPDATE...
ISSUED AT 1244 PM CDT SAT AUG 24 2013
GOING THROUGH THIS AFTERNOON...WILL BE WATCHING THE EFFECTS OF
CONTINUED ISENTROPIC LIFT AND FRINGES OF 850-700MB MOISTURE TRANSPORT
AHEAD OF AN APPROACHING WARM FRONT FROM THE PLAINS. RAP/NAM
INDICATING MODERATE AMOUNT OF LIFT THROUGH THE AFTERNOON TO
WARRANT AT LEAST A SLIGHT CHANCE MENTION OF SHOWERS AND ISOLATED
THUNDERSTORMS AS 1-3KM MLCAPE HOVERS IN THE 500-1000J/KG RANGE.
TEMPERATURES LOOK ON TRACK WITH HIGHS TOPPING OFF IN THE 80-85
DEGREE RANGE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SAT AUG 24 2013
MAIN SHORT TERM FORECAST CONCERN IS ON PRECIPITATION CHANCES.
CURRENTLY AS OF 08Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST
OFF THE PACIFIC NORTHWEST COAST AND OVER NEW ENGLAND...WHILE STRONG
SUBTROPICAL RIDGING DOMINATED THE CENTRAL AND SOUTHERN PLAINS.
NUMEROUS MONSOONAL SHORTWAVES WERE PRESENT ON THE WEST SIDE OF THE
RIDGE...FROM ARIZONA INTO WYOMING AND SOUTH DAKOTA. SOUTHERLY 850MB
WINDS OF 30-45 KT FROM KANSAS INTO WESTERN MN AHEAD OF THESE
SHORTWAVES ARE TRANSPORTING WARMER AND MORE MOIST AIR INTO THE UPPER
MIDWEST. PRECIPITABLE WATER VALUES HAVE CLIMBED TO 1.5-1.8 INCHES
FROM THE WESTERN PORTION OF THE FORECAST AREA INTO EASTERN PORTIONS
OF SOUTH DAKOTA AND NEBRASKA...PER SATELLITE DERIVED ESTIMATES.
MEANWHILE...850MB TEMPS HAVE CLIMBED TO 16-18C ACROSS THE FORECAST
AREA AND 22-28C ACROSS THE CENTRAL AND NORTHERN PLAINS PER RAP
ANALYSIS. THE GENERAL WARM ADVECTION PATTERN COMBINED WITH DPVA FROM
THE MONSOONAL SHORTWAVES HAS LED TO SOME SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS WYOMING...NEBRASKA AND SOUTH DAKOTA.
SYNOPTIC OVERVIEW...
THE SUBTROPICAL RIDGE OVER THE CENTRAL PLAINS IS PROGGED OVER THE
NEXT 24 HOURS TO BUILD INTO MISSOURI AND STRENGTHEN...CAUSING 500MB
HEIGHTS TO RISE ABOUT 30 METERS OVER THE FORECAST AREA. FOR THE MOST
PART IT APPEARS THE MONSOONAL SHORTWAVES COMING FROM THE ROCKIES
LOOK TO TRACK ACROSS THE DAKOTAS INTO NORTHWEST ONTARIO. THE ONE
SHORTWAVE OVER SOUTH DAKOTA MODELS SHOWED YESTERDAY TO COME ACROSS
THE FORECAST AREA TODAY IS PRETTY MUCH NON-EXISTENT IN MODELS TODAY.
NEVERTHELESS...WITH THE BUILDING RIDGING...THE WARM ADVECTION
PATTERN ACROSS THE UPPER MIDWEST WILL CONTINUE.
DETAILS...
THE QUESTION TODAY IS THE CHANCES OF PRECIPITATION NOW THAT THE
SHORTWAVE FROM SOUTH DAKOTA IS NO LONGER PRESENT. THE SIGNAL FOR
POSSIBLE SHOWER/THUNDERSTORM INITIATION ON THE EASTERN EDGE OF THE
850MB MOISTURE TRANSPORT IS STILL THERE...SUGGESTED BETWEEN 09-15Z
IN THE 24.00Z NAM/REGIONAL CANADIAN AND GFS. AFTER THAT...MODELS
HAVE DEFINITELY TRENDED DRIER FOR THE REST OF THE DAY. THIS MAKES
SENSE WITH THE BUILDING HEIGHTS. NOW THE 24.00Z NAM DOES TRY TO
GENERATE SOME ISOLATED CONVECTION OVER THE NORTHWEST HALF OF THE
AREA LATE IN THE AFTERNOON. HOWEVER...LOOKING AT SOUNDINGS THIS
SEEMS TO BE COMPLETELY TIED TO THE CONVECTIVE SCHEME AND ODD...WITH
MLCIN DROPPING FROM 70-80 J/KG TO 0 J/KG IN 1 HOUR WHILE A SUBSIDENT
PROFILE IS PRESENT. GIVEN THE CONSENSUS FOR A DRY AFTERNOON...WENT
IN THIS DIRECTION. BULK OF THE CONVECTION ALSO LOOKS TO STAY NORTH
OF THE FORECAST AREA TONIGHT WITH THE 850MB MOISTURE TRANSPORT
STREAM MOVING OVERHEAD...WHILE ITS NOSE IS FOCUSED FROM NORTHERN MN
ACROSS LAKE SUPERIOR AND UPPER MI. HAVE SHIFTED CHANCES NORTH TO
ONLY INCLUDE TAYLOR/CLARK NOW...TO ACCOUNT FOR THE DRYING
TREND...AND THESE MIGHT BE ABLE TO BE SHIFTED COMPLETELY OUT OF THE
AREA.
PARTIAL SUNSHINE TODAY COMBINED WITH 925/850MB TEMPS ABOUT 2C WARMER
SHOULD ALLOW HIGHS TO TOP OUT SIMILAR TO OR JUST SLIGHTLY WARMER
COMPARED TO YESTERDAY. CONDITIONS WILL BE A BIT MORE
MUGGY...THOUGH...AS HIGHER DEWPOINTS IN THE UPPER 60S TO LOW 70S
ADVECT IN ON INCREASING SOUTHERLY WINDS. THE SOUTHERLY BREEZE IS
EXPECTED TO PERSIST INTO TONIGHT...ALLOWING THE AFOREMENTIONED
DEWPOINTS TO SPREAD ACROSS THE FORECAST AREA. THE HIGHER DEWPOINTS
AND BREEZE SHOULD HELP KEEP TEMPERATURES UP IN THE MID 60S TO LOW
70S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 320 AM CDT SAT AUG 24 2013
HAZARDS...
1. HEAT. CONFIDENCE REMAINS HIGH THAT HEAT INDICES WILL EXCEED
ADVISORY CRITERIA BOTH MONDAY AND TUESDAY. A FEW LOCALIZED SPOTS
COULD EVEN TOUCH EXCESSIVE HEAT WARNING CRITERIA OF 105.
ADDITIONALLY...SUNDAY NOW LOOKS A LITTLE HIGHER FOR HEAT INDICES...
MORE CLOSER TO 100. GIVEN THESE CONDITIONS AS WELL AS WARM OVERNIGHT
LOWS...HAVE ISSUED A HEAT ADVISORY FOR SUNDAY THROUGH TUESDAY.
2. STORMS. THERE ARE PERIODIC STORM CHANCES THROUGHOUT THE LONG TERM
PORTION OF THE FORECAST...PARTICULARLY NORTH/EAST OF I-94.
HOWEVER...0-6KM AND 0-3 KM SHEAR VALUES ARE NEVER THAT IMPRESSIVE...
GENERALLY 25 KT OR LESS. THIS WILL KEEP HEAVY RAIN AS THE MOST
LIKELY HAZARD FROM THE STORMS.
SYNOPTIC OVERVIEW...
THE STRONG SUBTROPICAL RIDGE OVER MISSOURI TO START AT 12Z SUNDAY IS
WELL AGREED UPON BY 24.00Z GUIDANCE TO RETROGRADE WESTWARD THROUGH
THE MIDDLE OF THE WEEK. THIS RETROGRESSION IS CAUSED BY A SERIES OF
SHORTWAVE TROUGHS DROPPING DOWN THE EAST SIDE OF THE RIDGE INTO NEW
ENGLAND...THE MOST IMPRESSIVE OF WHICH CROSSES NEAR THE GREAT LAKES
REGION TUESDAY NIGHT. THE RETROGRESSION DOESNT LAST LONG...
THOUGH...AS A MORE POTENT UPPER TROUGH COMES INTO THE PACIFIC
NORTHWEST LATE IN THE WEEK...HELPING TO PUSH THE RIDGING AND ITS
WARMTH BACK EASTWARD.
PRECIPITATION DETAILS...
SUNDAY CONTINUES TO LOOK DRY WITH ALL SHORTWAVE AND 850MB MOISTURE
TRANSPORT FORCING TRACKING ACROSS LAKE SUPERIOR OR FARTHER NORTH.
THE 24.00Z NAM...HIRES ARW/NMM INITIATES SURFACE BASED CONVECTION
OVER CENTRAL MN LATE SUNDAY AFTERNOON...ALONG A SURFACE TROUGH. THE
CONVECTION THEN DROPS SOUTH TOWARDS I-90 IN THE EVENING. THESE
APPEAR TO BE STRONGLY DRIVEN BY TEMPERATURES REACHING 100F OR SO
ALONG THE TROUGH...WHICH IS THE CONVECTIVE TEMPERATURE. WHETHER OR
NOT THIS HAPPENS IS UNKNOWN...BUT JUST IN CASE DID INCLUDE 20-40
PERCENT CHANCES ALONG/NORTH OF I-90 IN THE EVENING. THESE CHANCES
CONTINUE INTO THE OVERNIGHT HOURS FOR A SECOND SCENARIO...WHERE
CONVECTION FIRES UP IN NORTHWEST WISCONSIN IN THE EVENING AND DROPS
SOUTH FOLLOWING CORFIDI VECTORS. THIS IS PRESENTED BY THE 24.00Z
GFS/ECMWF. IT SHOULD BE NOTED...THOUGH...THE 24.00Z CANADIAN/UKMET
ARE DRY...KEEPING ALL CONVECTION TO THE NORTH OF THE AREA. ALSO
INTERESTING TO NOTE IS THAT THE NAM...GFS AND ECMWF ARE ALL DRY
MONDAY MORNING...SUGGESTING CONVECTION WEAKENS AS IT RUNS INTO THE
CAPPING OVER THE AREA.
ALL MODELS INDICATE THAT AN OUTFLOW BOUNDARY/WARM FRONT SHOULD BE
LOCATED SOUTH OF THE OVERNIGHT CONVECTION...SETTING UP NEAR I-94 FOR
MONDAY AFTERNOON. 24.00Z GFS/ECMWF BOTH FIRE SOME CONVECTION ALONG
THIS BOUNDARY WHICH WOULD APPEAR POSSIBLE GIVEN THE HOT AND HUMID
AIRMASS IMPINGING ON IT FROM THE SOUTHWEST. THEREFORE...CARRIED 20
PERCENT CHANCES ALONG/NORTH OF I-94 FOR THE AFTERNOON. THESE CHANCES
PERSIST THROUGH MONDAY NIGHT AND TUESDAY...AIDED BY INCREASING 850MB
MOISTURE TRANSPORT AHEAD OF A MORE SIGNIFICANT SHORTWAVE TRACKING
ACROSS THE DAKOTAS...INTO NW MINNESOTA AND LAKE SUPERIOR. GREATER
CHANCES FOR CONVECTION MONDAY NIGHT AND TUESDAY SHOULD STAY OFF TO
THE NORTH AND NORTHEAST CLOSER TO THAT SHORTWAVE TRACK.
A COLD FRONT IS PROGGED TO DROP THROUGH TUESDAY NIGHT. PLENTY OF
CAPPING AHEAD OF THE FRONT SHOULD RESTRICT SURFACE BASED CONVECTION
ON IT...WITH DRY CONDITIONS LIKELY IN ITS WAKE FOR WEDNESDAY INTO
THURSDAY. CHANCES OF SHOWERS AND STORMS RETURN THURSDAY NIGHT
THROUGH FRIDAY NIGHT AS THE FRONT GRADUALLY RETURNS BACK
NORTHEASTWARD AS A WARM FRONT.
TEMPERATURE DETAILS...
SUNDAY...WITH PLENTY OF SUN...BREEZY SOUTHWEST WINDS AND 925 MB
TEMPS CLIMBING TO 26-28C...HIGH TEMPS SHOULD EASILY TOP OUT IN THE
UPPER 80S TO LOW 90S. A FEW VALLEY LOCATIONS COULD EVEN HIT THE MID
90S. WITH DEWPOINTS LIKELY IN THE UPPER 60S TO LOW 70S...PEAK HEAT
INDICES OF 95 TO 100 SHOULD BE COMMON...HIGHEST OVER THE NORTHWEST
HALF OF THE FORECAST AREA.
MONDAY...INDICATIONS ARE THAT THERE SHOULD STILL BE PLENTY OF
SUN...EVEN IF THERE IS ANY DISSIPATING MORNING CONVECTION OR
AFTERNOON DEVELOPMENT. WITH 925MB TEMPS CLIMBING FURTHER TO AROUND
28C TO POSSIBLY EVEN 30C PER GFS...HIGHS IN THE LOW TO MID 90S ARE
LIKELY. COMBINED WITH DEWPOINTS STAYING ABOUT THE SAME RESULTS IN
PEAK HEAT INDICES OF 100 TO 105.
TUESDAY...WILL HAVE TO WATCH THIS DAY CLOSELY AS IT COULD BE THE
HOTTEST OF THE WEEK. AHEAD OF THE APPROACHING COLD FRONT...A
SOUTHWEST TO WEST WIND PUSH OF THE HOT PLAINS AIR ADVECTS OVER THE
AREA. 925MB TEMPS OF 29-31C PER ECMWF/GFS ARE PROGGED WHICH COULD
PUSH TEMPS TOWARDS 100F. ONLY CONCERN IS THE LOWER SUN ANGLE
COMPARED TO SAY JULY. RAISED HIGHS A COUPLE DEGREES BUT MORE
INCREASES MAY BE NEEDED. NEW FORECAST HIGHS ARE AT RECORDS. HEAT
INDICES AGAIN LOOK TO PEAK OUT AT 100-105.
A COOL DOWN BUT STILL STAYING WELL ABOVE NORMAL IS PROGGED FOR
WEDNESDAY AND THURSDAY. FRIDAY IS A BIT MORE UNCERTAIN WITH THE
24.00Z ECMWF SHOWING ANOTHER SHORTWAVE DROPPING THROUGH THE GREAT
LAKES...SLOWING DOWN THE EASTWARD MOVEMENT OF THE UPPER RIDGE.
FRIDAY PREVIOUSLY LOOKED LIKE WHEN THE HEAT WOULD RETURN. HEAT STILL
ON TARGET TO RETURN DURING LABOR DAY WEEKEND...HOWEVER.
LEANED TOWARDS THE WARM SIDE OF RAW MODEL GUIDANCE FOR LOWS SUNDAY
NIGHT AND MONDAY NIGHT. CONSENSUS OF MODEL GUIDANCE USED THEREAFTER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1244 PM CDT SAT AUG 24 2013
CONTINUED LIFT THROUGH THE MID-LEVELS OF THE ATMOSPHERE AHEAD OF
AN APPROACHING WARM FRONT OUT OF THE PLAINS WILL CONTINUE A SLIGHT
CHANCE OF SHRA/ISOLD THUNDER ACROSS THE AREA THROUGH THIS
AFTERNOON. SINCE THIS LIFT IS OCCURRING AOA 5KFT...ANY CLOUDS
SHOULD BE VFR IN NATURE. HAVE INCLUDED VCSH IN THE KRST/KLSE TAF
IN THE 20-01Z TIME FRAME. APPEARS ANY SHRA/THUNDER CHANCES SHIFTS
NORTHEAST OF THE AREA AFTER SUNSET. ATTENTION THEN TURNS TO LLWS
OVERNIGHT WITH MODEL WIND PROFILES SHOWING 45-50KT OUT OF THE
SOUTHWEST MATERIALIZING AOA 1500 FT AGL AFTER 04Z. FOR THIS REASON...HAVE
INCLUDED LLWS FOR BOTH KRST/KLSE TAF SITES FROM 04Z THROUGH 13Z.
LOOK FOR GUSTY SOUTH-SOUTHWEST WINDS SUNDAY AS THE PRESSURE
GRADIENT INCREASES ACROSS THE REGION. OTHERWISE...EXPECTING VFR
CONDITIONS THROUGH SUNDAY MORNING.
&&
.CLIMATE...
ISSUED AT 307 PM CDT FRI AUG 23 2013
HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR
DAY WEEKEND GIVEN THE UPCOMING INCREASE IN HEAT. FOR MORE CLIMATE
INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ017-029-032>034-041>044-053>055-061.
MN...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-086>088-094>096.
IA...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
IAZ008>011-018-019-029-030.
&&
$$
UPDATE...DAS
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
CLIMATE...DAS/AJ
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1057 AM CDT SAT AUG 24 2013
.UPDATE...
LAST FEW RUNS OF HRRR AND WRF4L NOW BRING SOME PRECIPITATION INTO
THE WESTERN CWA...TIED TO THE LINE OF PRECIP CURRENTLY MOVING ACROSS
WESTERN WI. RADAR SHOWS SOME PRECIP FORMING OVER SOUTHWEST WI.
CURRENT ANALYSIS INDICATES SHARP DEW POINT GRADIENT AND LOW LEVEL
MOISTURE ADVECTION ACROSS THE WEST AND SOUNDINGS INDICATE WEAK
INSTABILITY IN THIS AREA THIS AFTERNOON. MAY INTRODUCE LOW POPS FROM
MADISON WESTWARD FOR THIS AFTERNOON IF THIS TREND CONTINUES.
THESE MODELS SHOW A SLIGHT CHANCE OF PRECIP IN WESTERN CWA AFTER
00Z...ASSOCIATED WITH SHORTWAVE AND PRECIP CURRENTLY OVER NW IOWA.
&&
.AVIATION/18Z TAFS/...
VFR CONDITIONS WILL CONTINUE THROUGH THE SUNDAY. THERE IS AN
OUTSIDE CHANCE FOR A SHOWER OR STORM THIS AFTERNOON FOR AREAS WEST
OF MADISON...BUT EXPECTING MOST PLACES TO REMAIN DRY. A VERY WEAK
WAVE MAY KICK OFF A COUPLE SHOWERS OR STORMS THIS EVENING OR
TONIGHT...BUT AGAIN IT LOOKS LIKE MAINLY DRY WEATHER THROUGH THE
DAY SUNDAY. MORE CLOUDS AND LOW LEVEL WIND ARE EXPECTED
TONIGHT THAN THE LAST COUPLE DAYS...SO SHOULD NOT SEE MUCH IN THE
WAY OF FOG.
&&
.PREV DISCUSSION... /ISSUED 355 AM CDT SAT AUG 24 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.
UPPER RIDGE BUILDING INTO THE REGION WITH WEAK SHORT WAVE PASSING
WELL NORTH OF FORECAST AREA. HRRR CURRENTLY HAS A BETTER HANDLE
THAN OPERATIONAL MODELS WITH PRECIPITATION OVER ERN
NEBRASKA...THAT WILL TRACK WITH BEST FRONTOGENETIC
FORCING/Q VECTOR CONVERGENCE/ISENTROPIC LIFT SHOWN ON ALL MODELS
TO THE W AND N OF CWA. THUS HAVE REMOVED SLIGHT POPS FROM THE WEST
FOR THIS AFTERNOON AND CHC POPS FOR TONIGHT ACROSS THE FAR NORTH.
925 MB TEMPERATURES WARM ABOUT 2C FROM YESTERDAY SO DECENT MIXING
WILL YIELD HIGHS IN THE MID TO UPPER 80S IN THE WEST...WITH AROUND
80 IN THE EAST AS WINDS OFF OF THE LAKE WILL HOLD READINGS DOWN.
EXPECT ENOUGH GRADIENT WIND AND SUFFICIENT DEW POINT DEPRESSION IN
THE WEST TO NOT HAVE FOG IN FORECAST...EVEN IN THE WISCONSIN RIVER
VALLEY. LIGHTER WINDS EAST MAY ALLOW SOME PATCHY FOG AROUND
SUNRISE.
SUNDAY THROUGH MONDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM.
SHORT TERM MODELS SHOWING 500MB HIGH RETREATING FROM MISSOURI ON
SUNDAY TO KANSAS BY MONDAY NIGHT. THIS ALLOWS FOR WEST NORTHWEST
TO NORTHWEST FLOW AT THIS LEVEL OVER THE WESTERN GREAT LAKES
REGION. AT THE SURFACE...SOUTHWEST LOW LEVEL WINDS BRINGS VERY
WARM AIRMASS INTO THE REGION SUNDAY. AIRMASS IS EXPECTED TO BE
CAPPED.
925MB TEMPERATURES SUGGESTING HIGHS MAINLY AROUND 90 OR IN THE
LOWER 90S. DEW POINTS WILL ALSO BE IN THE LOWER TO MID 60S...WHICH
WILL GIVE HEAT INDEX VALUES IN THE 90 TO 95 RANGE ACROSS THE AREA.
NAM/GFS SHOW 500MB VORTICITY MAXIMUM SLIDING SOUTHEAST ACROSS
NORTHEAST PORTIONS OF THE FORECAST AREA LATER SUNDAY NIGHT.
NAM/GFS HAVE LIGHT QPF WITH THIS FEATURE DURING THIS TIME. ADDED
LOWER END POPS IN THE NORTHERN AND NORTHEASTERN COUNTIES FOR
MAINLY LATER SUNDAY NIGHT. LOWS WILL REMAIN WARM...IN THE LOWER 70S.
GFS/ECMWF/CANADIAN MODELS SHOW WARM FRONT STALLING OUT FROM
CENTRAL MINNESOTA INTO SOUTHEAST WISCONSIN MONDAY INTO MONDAY
NIGHT. THE NAM IS FURTHER SOUTHWEST THAN THE OTHER MODELS WITH THE
FRONTAL POSITION...PERHAPS TOO FAR SOUTHWEST. BEST FORCING FOR
UPWARD VERTICAL MOTION REMAINS WELL NORTHWEST AND NORTH OF THE
AREA DURING THIS TIME.
AREA FORECAST SOUNDINGS ARE SHOWING AMPLE MEAN LAYER CAPE/MODEST
DEEP LAYER SHEAR WITH A WEAK CAP MONDAY...BECOMING MORE ELEVATED
IN NATURE WITH THE CAPE MONDAY NIGHT. KEPT POPS GOING FOR THIS
PERIOD IN THE NORTHEAST HALF OF THE AREA...CLOSEST TO THE LOW
LEVEL FRONTOGENESIS RESPONSE FIELDS.
AREA REMAINS IN WARM SECTOR AIRMASS MONDAY INTO MONDAY NIGHT PER
GFS/ECMWF/CANADIAN MODELS. 925MB TEMPERATURES SUGGEST HIGHS IN THE
LOWER TO PERHAPS MID 90S MONDAY...WITH HEAT INDEX VALUES IN THE
95 TO 101 DEGREE RANGE.
TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE IS MEDIUM.
GFS/ECMWF SHOW SOME DIFFERENCES WITH TRENDS DURING THIS PERIOD.
THE 500MB HIGH REMAINS OVER THE KANSAS AREA DURING THIS PERIOD.
THE GFS CONTINUES TO BE FURTHER SOUTH WITH THE PASSING LOW
PRESSURE SYSTEM AND FRONTAL BOUNDARY TUESDAY INTO TUESDAY NIGHT.
DECENT MEAN LAYER CAPES OF 1000 TO 1300 J/KG WITH DECENT DEEP
LAYER SHEAR AROUND 30 TO 35 KNOTS ARE SHOWN ON GFS FORECAST
SOUNDINGS. ECMWF IS DRY WITH THE FRONTAL PASSAGE.
BOTH MODELS DO SHOW COLD FRONT DROPPING SOUTHWARD THROUGH THE AREA
TUESDAY NIGHT. CONTINUED POPS FOR TUESDAY AND TUESDAY
NIGHT IN THE NORTHEASTERN HALF OF COUNTIES...CLOSEST TO THE LOW.
AREA REMAINS IN WARM SECTOR AIRMASS ON ECMWF AND GFS...WITH 925MB
TEMPERATURES SUPPORTING ANOTHER DAY OF LOWER TO PERHAPS MID 90S
FOR HIGHS. HEAT INDEX VALUES SHOULD REACH THE 95 TO 101 RANGE
AGAIN. COUNTING WEDNESDAY...THERE WOULD BE THREE DAYS IN A ROW OF
HEAT INDEX VALUES IN THE 95 TO 100 DEGREE RANGE IN SOUTH CENTRAL
WISCONSIN. NEED FOUR IN A ROW FOR A HEAT ADVISORY. IT STILL MAY BE
NEEDED FOR MONDAY AND TUESDAY ACROSS THE AREA...IF DAILY HEAT
INDEX VALUES CONTINUE TO REMAIN AROUND OR ABOVE 100. FOR
NOW...WILL CONTINUE MENTION POTENTIAL IN HAZARDOUS WEATHER
OUTLOOK AND SPECIAL WEATHER STATEMENT.
MODEST COLD AIR ADVECTION AHEAD OF HIGH PRESSURE PUSHES INTO THE
AREA WEDNESDAY ON NORTH TO NORTHEAST WINDS...BRINGING SLIGHTLY
COOLER BUT STILL ABOVE NORMAL TEMPERATURES. HIGH PRESSURE THEN
MOVES SLOWLY SOUTHEAST THROUGH THE REGION THROUGH
THURSDAY...BRINGING QUIET WEATHER AND WARM TEMPERATURES.
WARM AIR ADVECTION AND MOISTURE ADVECTION THEN TRY TO PUSH BACK
INTO PORTIONS OF THE REGION THURSDAY NIGHT INTO FRIDAY...MORE SO
ON ECMWF THAN GFS. USED CONSENSUS POPS FOR NOW IN THIS PERIOD.
AVIATION/12Z TAFS/...ONCE PATCHY MVFR FOG AT KENW AND KUES CLEARS
THIS MORNING...LOOKING AT VFR CONDITIONS THROUGH THE DAY. LIGHT
WINDS OVER THE EAST BRINGS POTENTIAL FOR PATCHY MVFR FOG
REDEVELOPMENT AT KENW TONIGHT...BUT DEW POINT DEPRESSIONS OF 4 TO
6 DEGREES WILL LIKELY PREVENT FORMATION SO WILL LEAVE OUT FOR NOW.
MARINE...STILL LOOKS LIKE BREEZY SOUTHWEST WINDS WILL APPROACH
SMALL CRAFT ADVISORY LEVELS ON SUNDAY...ESPECIALLY CLOSE TO SHORE.
WILL MENTION POTENTIAL IN FORECAST BUT NOT ISSUE A HEADLINE AT
THIS TIME.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...SM/DDV
TODAY/TONIGHT AND AVIATION/MARINE...REM
SUNDAY THROUGH FRIDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
645 AM CDT SAT AUG 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SAT AUG 24 2013
MAIN SHORT TERM FORECAST CONCERN IS ON PRECIPITATION CHANCES.
CURRENTLY AS OF 08Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST
OFF THE PACIFIC NORTHWEST COAST AND OVER NEW ENGLAND...WHILE STRONG
SUBTROPICAL RIDGING DOMINATED THE CENTRAL AND SOUTHERN PLAINS.
NUMEROUS MONSOONAL SHORTWAVES WERE PRESENT ON THE WEST SIDE OF THE
RIDGE...FROM ARIZONA INTO WYOMING AND SOUTH DAKOTA. SOUTHERLY 850MB
WINDS OF 30-45 KT FROM KANSAS INTO WESTERN MN AHEAD OF THESE
SHORTWAVES ARE TRANSPORTING WARMER AND MORE MOIST AIR INTO THE UPPER
MIDWEST. PRECIPITABLE WATER VALUES HAVE CLIMBED TO 1.5-1.8 INCHES
FROM THE WESTERN PORTION OF THE FORECAST AREA INTO EASTERN PORTIONS
OF SOUTH DAKOTA AND NEBRASKA...PER SATELLITE DERIVED ESTIMATES.
MEANWHILE...850MB TEMPS HAVE CLIMBED TO 16-18C ACROSS THE FORECAST
AREA AND 22-28C ACROSS THE CENTRAL AND NORTHERN PLAINS PER RAP
ANALYSIS. THE GENERAL WARM ADVECTION PATTERN COMBINED WITH DPVA FROM
THE MONSOONAL SHORTWAVES HAS LED TO SOME SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS WYOMING...NEBRASKA AND SOUTH DAKOTA.
SYNOPTIC OVERVIEW...
THE SUBTROPICAL RIDGE OVER THE CENTRAL PLAINS IS PROGGED OVER THE
NEXT 24 HOURS TO BUILD INTO MISSOURI AND STRENGTHEN...CAUSING 500MB
HEIGHTS TO RISE ABOUT 30 METERS OVER THE FORECAST AREA. FOR THE MOST
PART IT APPEARS THE MONSOONAL SHORTWAVES COMING FROM THE ROCKIES
LOOK TO TRACK ACROSS THE DAKOTAS INTO NORTHWEST ONTARIO. THE ONE
SHORTWAVE OVER SOUTH DAKOTA MODELS SHOWED YESTERDAY TO COME ACROSS
THE FORECAST AREA TODAY IS PRETTY MUCH NON-EXISTENT IN MODELS TODAY.
NEVERTHELESS...WITH THE BUILDING RIDGING...THE WARM ADVECTION
PATTERN ACROSS THE UPPER MIDWEST WILL CONTINUE.
DETAILS...
THE QUESTION TODAY IS THE CHANCES OF PRECIPITATION NOW THAT THE
SHORTWAVE FROM SOUTH DAKOTA IS NO LONGER PRESENT. THE SIGNAL FOR
POSSIBLE SHOWER/THUNDERSTORM INITIATION ON THE EASTERN EDGE OF THE
850MB MOISTURE TRANSPORT IS STILL THERE...SUGGESTED BETWEEN 09-15Z
IN THE 24.00Z NAM/REGIONAL CANADIAN AND GFS. AFTER THAT...MODELS
HAVE DEFINITELY TRENDED DRIER FOR THE REST OF THE DAY. THIS MAKES
SENSE WITH THE BUILDING HEIGHTS. NOW THE 24.00Z NAM DOES TRY TO
GENERATE SOME ISOLATED CONVECTION OVER THE NORTHWEST HALF OF THE
AREA LATE IN THE AFTERNOON. HOWEVER...LOOKING AT SOUNDINGS THIS
SEEMS TO BE COMPLETELY TIED TO THE CONVECTIVE SCHEME AND ODD...WITH
MLCIN DROPPING FROM 70-80 J/KG TO 0 J/KG IN 1 HOUR WHILE A SUBSIDENT
PROFILE IS PRESENT. GIVEN THE CONSENSUS FOR A DRY AFTERNOON...WENT
IN THIS DIRECTION. BULK OF THE CONVECTION ALSO LOOKS TO STAY NORTH
OF THE FORECAST AREA TONIGHT WITH THE 850MB MOISTURE TRANSPORT
STREAM MOVING OVERHEAD...WHILE ITS NOSE IS FOCUSED FROM NORTHERN MN
ACROSS LAKE SUPERIOR AND UPPER MI. HAVE SHIFTED CHANCES NORTH TO
ONLY INCLUDE TAYLOR/CLARK NOW...TO ACCOUNT FOR THE DRYING
TREND...AND THESE MIGHT BE ABLE TO BE SHIFTED COMPLETELY OUT OF THE
AREA.
PARTIAL SUNSHINE TODAY COMBINED WITH 925/850MB TEMPS ABOUT 2C WARMER
SHOULD ALLOW HIGHS TO TOP OUT SIMILAR TO OR JUST SLIGHTLY WARMER
COMPARED TO YESTERDAY. CONDITIONS WILL BE A BIT MORE
MUGGY...THOUGH...AS HIGHER DEWPOINTS IN THE UPPER 60S TO LOW 70S
ADVECT IN ON INCREASING SOUTHERLY WINDS. THE SOUTHERLY BREEZE IS
EXPECTED TO PERSIST INTO TONIGHT...ALLOWING THE AFOREMENTIONED
DEWPOINTS TO SPREAD ACROSS THE FORECAST AREA. THE HIGHER DEWPOINTS
AND BREEZE SHOULD HELP KEEP TEMPERATURES UP IN THE MID 60S TO LOW
70S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 320 AM CDT SAT AUG 24 2013
HAZARDS...
1. HEAT. CONFIDENCE REMAINS HIGH THAT HEAT INDICES WILL EXCEED
ADVISORY CRITERIA BOTH MONDAY AND TUESDAY. A FEW LOCALIZED SPOTS
COULD EVEN TOUCH EXCESSIVE HEAT WARNING CRITERIA OF 105.
ADDITIONALLY...SUNDAY NOW LOOKS A LITTLE HIGHER FOR HEAT INDICES...
MORE CLOSER TO 100. GIVEN THESE CONDITIONS AS WELL AS WARM OVERNIGHT
LOWS...HAVE ISSUED A HEAT ADVISORY FOR SUNDAY THROUGH TUESDAY.
2. STORMS. THERE ARE PERIODIC STORM CHANCES THROUGHOUT THE LONG TERM
PORTION OF THE FORECAST...PARTICULARLY NORTH/EAST OF I-94.
HOWEVER...0-6KM AND 0-3 KM SHEAR VALUES ARE NEVER THAT IMPRESSIVE...
GENERALLY 25 KT OR LESS. THIS WILL KEEP HEAVY RAIN AS THE MOST
LIKELY HAZARD FROM THE STORMS.
SYNOPTIC OVERVIEW...
THE STRONG SUBTROPICAL RIDGE OVER MISSOURI TO START AT 12Z SUNDAY IS
WELL AGREED UPON BY 24.00Z GUIDANCE TO RETROGRADE WESTWARD THROUGH
THE MIDDLE OF THE WEEK. THIS RETROGRESSION IS CAUSED BY A SERIES OF
SHORTWAVE TROUGHS DROPPING DOWN THE EAST SIDE OF THE RIDGE INTO NEW
ENGLAND...THE MOST IMPRESSIVE OF WHICH CROSSES NEAR THE GREAT LAKES
REGION TUESDAY NIGHT. THE RETROGRESSION DOESNT LAST LONG...
THOUGH...AS A MORE POTENT UPPER TROUGH COMES INTO THE PACIFIC
NORTHWEST LATE IN THE WEEK...HELPING TO PUSH THE RIDGING AND ITS
WARMTH BACK EASTWARD.
PRECIPITATION DETAILS...
SUNDAY CONTINUES TO LOOK DRY WITH ALL SHORTWAVE AND 850MB MOISTURE
TRANSPORT FORCING TRACKING ACROSS LAKE SUPERIOR OR FARTHER NORTH.
THE 24.00Z NAM...HIRES ARW/NMM INITIATES SURFACE BASED CONVECTION
OVER CENTRAL MN LATE SUNDAY AFTERNOON...ALONG A SURFACE TROUGH. THE
CONVECTION THEN DROPS SOUTH TOWARDS I-90 IN THE EVENING. THESE
APPEAR TO BE STRONGLY DRIVEN BY TEMPERATURES REACHING 100F OR SO
ALONG THE TROUGH...WHICH IS THE CONVECTIVE TEMPERATURE. WHETHER OR
NOT THIS HAPPENS IS UNKNOWN...BUT JUST IN CASE DID INCLUDE 20-40
PERCENT CHANCES ALONG/NORTH OF I-90 IN THE EVENING. THESE CHANCES
CONTINUE INTO THE OVERNIGHT HOURS FOR A SECOND SCENARIO...WHERE
CONVECTION FIRES UP IN NORTHWEST WISCONSIN IN THE EVENING AND DROPS
SOUTH FOLLOWING CORFIDI VECTORS. THIS IS PRESENTED BY THE 24.00Z
GFS/ECMWF. IT SHOULD BE NOTED...THOUGH...THE 24.00Z CANADIAN/UKMET
ARE DRY...KEEPING ALL CONVECTION TO THE NORTH OF THE AREA. ALSO
INTERESTING TO NOTE IS THAT THE NAM...GFS AND ECMWF ARE ALL DRY
MONDAY MORNING...SUGGESTING CONVECTION WEAKENS AS IT RUNS INTO THE
CAPPING OVER THE AREA.
ALL MODELS INDICATE THAT AN OUTFLOW BOUNDARY/WARM FRONT SHOULD BE
LOCATED SOUTH OF THE OVERNIGHT CONVECTION...SETTING UP NEAR I-94 FOR
MONDAY AFTERNOON. 24.00Z GFS/ECMWF BOTH FIRE SOME CONVECTION ALONG
THIS BOUNDARY WHICH WOULD APPEAR POSSIBLE GIVEN THE HOT AND HUMID
AIRMASS IMPINGING ON IT FROM THE SOUTHWEST. THEREFORE...CARRIED 20
PERCENT CHANCES ALONG/NORTH OF I-94 FOR THE AFTERNOON. THESE CHANCES
PERSIST THROUGH MONDAY NIGHT AND TUESDAY...AIDED BY INCREASING 850MB
MOISTURE TRANSPORT AHEAD OF A MORE SIGNIFICANT SHORTWAVE TRACKING
ACROSS THE DAKOTAS...INTO NW MINNESOTA AND LAKE SUPERIOR. GREATER
CHANCES FOR CONVECTION MONDAY NIGHT AND TUESDAY SHOULD STAY OFF TO
THE NORTH AND NORTHEAST CLOSER TO THAT SHORTWAVE TRACK.
A COLD FRONT IS PROGGED TO DROP THROUGH TUESDAY NIGHT. PLENTY OF
CAPPING AHEAD OF THE FRONT SHOULD RESTRICT SURFACE BASED CONVECTION
ON IT...WITH DRY CONDITIONS LIKELY IN ITS WAKE FOR WEDNESDAY INTO
THURSDAY. CHANCES OF SHOWERS AND STORMS RETURN THURSDAY NIGHT
THROUGH FRIDAY NIGHT AS THE FRONT GRADUALLY RETURNS BACK
NORTHEASTWARD AS A WARM FRONT.
TEMPERATURE DETAILS...
SUNDAY...WITH PLENTY OF SUN...BREEZY SOUTHWEST WINDS AND 925 MB
TEMPS CLIMBING TO 26-28C...HIGH TEMPS SHOULD EASILY TOP OUT IN THE
UPPER 80S TO LOW 90S. A FEW VALLEY LOCATIONS COULD EVEN HIT THE MID
90S. WITH DEWPOINTS LIKELY IN THE UPPER 60S TO LOW 70S...PEAK HEAT
INDICES OF 95 TO 100 SHOULD BE COMMON...HIGHEST OVER THE NORTHWEST
HALF OF THE FORECAST AREA.
MONDAY...INDICATIONS ARE THAT THERE SHOULD STILL BE PLENTY OF
SUN...EVEN IF THERE IS ANY DISSIPATING MORNING CONVECTION OR
AFTERNOON DEVELOPMENT. WITH 925MB TEMPS CLIMBING FURTHER TO AROUND
28C TO POSSIBLY EVEN 30C PER GFS...HIGHS IN THE LOW TO MID 90S ARE
LIKELY. COMBINED WITH DEWPOINTS STAYING ABOUT THE SAME RESULTS IN
PEAK HEAT INDICES OF 100 TO 105.
TUESDAY...WILL HAVE TO WATCH THIS DAY CLOSELY AS IT COULD BE THE
HOTTEST OF THE WEEK. AHEAD OF THE APPROACHING COLD FRONT...A
SOUTHWEST TO WEST WIND PUSH OF THE HOT PLAINS AIR ADVECTS OVER THE
AREA. 925MB TEMPS OF 29-31C PER ECMWF/GFS ARE PROGGED WHICH COULD
PUSH TEMPS TOWARDS 100F. ONLY CONCERN IS THE LOWER SUN ANGLE
COMPARED TO SAY JULY. RAISED HIGHS A COUPLE DEGREES BUT MORE
INCREASES MAY BE NEEDED. NEW FORECAST HIGHS ARE AT RECORDS. HEAT
INDICES AGAIN LOOK TO PEAK OUT AT 100-105.
A COOL DOWN BUT STILL STAYING WELL ABOVE NORMAL IS PROGGED FOR
WEDNESDAY AND THURSDAY. FRIDAY IS A BIT MORE UNCERTAIN WITH THE
24.00Z ECMWF SHOWING ANOTHER SHORTWAVE DROPPING THROUGH THE GREAT
LAKES...SLOWING DOWN THE EASTWARD MOVEMENT OF THE UPPER RIDGE.
FRIDAY PREVIOUSLY LOOKED LIKE WHEN THE HEAT WOULD RETURN. HEAT STILL
ON TARGET TO RETURN DURING LABOR DAY WEEKEND...HOWEVER.
LEANED TOWARDS THE WARM SIDE OF RAW MODEL GUIDANCE FOR LOWS SUNDAY
NIGHT AND MONDAY NIGHT. CONSENSUS OF MODEL GUIDANCE USED THEREAFTER.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 644 AM CDT SAT AUG 24 2013
AN AREA OF SHOWERS HAS DEVELOPED AT THE NOSE OF SOME 850 TO 700 MB
MOISTURE TRANSPORT. THE MODELS ARE IN GENERAL AGREEMENT THAT THIS
TRANSPORT WILL DISSIPATE AND MOVE NORTH OF THE AREA BY 24.14Z. DUE
TO THIS...ONLY MENTIONED THE SHOWERS AT THE KRST TAF SITE THROUGH
THIS TIME...AND KEPT KLSE DRY. HOWEVER WE WILL HAVE TO WATCH A
THUNDERSTORM COMPLEX OVER SOUTHWEST MINNESOTA AND WESTERN IOWA.
THE RAP SEEMS TO HAVE A DECENT HANDLE ON THIS SYSTEM. IT TRACKS
THIS WEAKENING COMPLEX EAST INTO NORTHEAST IOWA LATE THIS MORNING.
AT THIS TIME...IT LOOKS LIKE THE PRECIPITATION WILL BE SOUTH OF
KRST AND KLSE...SO DID NOT MENTION IT IN THE TAF AT THIS TIME.
A TIGHT PRESSURE GRADIENT BETWEEN THE RETREATING HIGH OVER THE
EAST GREAT LAKES AND AN APPROACHING WARM FRONT WILL KEEP SUSTAINED
WINDS IN THE 10 TO 15 KNOT RANGE WITH WIND GUSTS OF 20 TO 30 KNOTS.
THESE GUSTS WILL RAPIDLY DIMINISH BETWEEN 25.00Z AND 25.03Z WITH
THE LOSS OF DIURNAL HEATING.
FOR TONIGHT...A SCATTERED TO BROKEN 10 TO 15K DECK WILL REMAIN
ACROSS THE AREA.
&&
.CLIMATE...
ISSUED AT 307 PM CDT FRI AUG 23 2013
HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR
DAY WEEKEND GIVEN THE UPCOMING INCREASE IN HEAT. FOR MORE CLIMATE
INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ017-029-032>034-041>044-053>055-061.
MN...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-086>088-094>096.
IA...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
CLIMATE...DAS/AJ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
355 AM CDT SAT AUG 24 2013
.TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.
UPPER RIDGE BUILDING INTO THE REGION WITH WEAK SHORT WAVE PASSING
WELL NORTH OF FORECAST AREA. HRRR CURRENTLY HAS A BETTER HANDLE
THAN OPERATIONAL MODELS WITH PRECIPITATION OVER ERN
NEBRASKA...THAT WILL TRACK WITH BEST FRONTOGENETIC
FORCING/Q VECTOR CONVERGENCE/ISENTROPIC LIFT SHOWN ON ALL MODELS
TO THE W AND N OF CWA. THUS HAVE REMOVED SLIGHT POPS FROM THE WEST
FOR THIS AFTERNOON AND CHC POPS FOR TONIGHT ACROSS THE FAR NORTH.
925 MB TEMPERATURES WARM ABOUT 2C FROM YESTERDAY SO DECENT MIXING
WILL YIELD HIGHS IN THE MID TO UPPER 80S IN THE WEST...WITH AROUND
80 IN THE EAST AS WINDS OFF OF THE LAKE WILL HOLD READINGS DOWN.
EXPECT ENOUGH GRADIENT WIND AND SUFFICIENT DEW POINT DEPRESSION IN
THE WEST TO NOT HAVE FOG IN FORECAST...EVEN IN THE WISCONSIN RIVER
VALLEY. LIGHTER WINDS EAST MAY ALLOW SOME PATCHY FOG AROUND
SUNRISE.
.SUNDAY THROUGH MONDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM.
SHORT TERM MODELS SHOWING 500MB HIGH RETREATING FROM MISSOURI ON
SUNDAY TO KANSAS BY MONDAY NIGHT. THIS ALLOWS FOR WEST NORTHWEST
TO NORTHWEST FLOW AT THIS LEVEL OVER THE WESTERN GREAT LAKES
REGION. AT THE SURFACE...SOUTHWEST LOW LEVEL WINDS BRINGS VERY
WARM AIRMASS INTO THE REGION SUNDAY. AIRMASS IS EXPECTED TO BE
CAPPED.
925MB TEMPERATURES SUGGESTING HIGHS MAINLY AROUND 90 OR IN THE
LOWER 90S. DEW POINTS WILL ALSO BE IN THE LOWER TO MID 60S...WHICH
WILL GIVE HEAT INDEX VALUES IN THE 90 TO 95 RANGE ACROSS THE AREA.
NAM/GFS SHOW 500MB VORTICITY MAXIMUM SLIDING SOUTHEAST ACROSS
NORTHEAST PORTIONS OF THE FORECAST AREA LATER SUNDAY NIGHT.
NAM/GFS HAVE LIGHT QPF WITH THIS FEATURE DURING THIS TIME. ADDED
LOWER END POPS IN THE NORTHERN AND NORTHEASTERN COUNTIES FOR
MAINLY LATER SUNDAY NIGHT. LOWS WILL REMAIN WARM...IN THE LOWER 70S.
GFS/ECMWF/CANADIAN MODELS SHOW WARM FRONT STALLING OUT FROM
CENTRAL MINNESOTA INTO SOUTHEAST WISCONSIN MONDAY INTO MONDAY
NIGHT. THE NAM IS FURTHER SOUTHWEST THAN THE OTHER MODELS WITH THE
FRONTAL POSITION...PERHAPS TOO FAR SOUTHWEST. BEST FORCING FOR
UPWARD VERTICAL MOTION REMAINS WELL NORTHWEST AND NORTH OF THE
AREA DURING THIS TIME.
AREA FORECAST SOUNDINGS ARE SHOWING AMPLE MEAN LAYER CAPE/MODEST
DEEP LAYER SHEAR WITH A WEAK CAP MONDAY...BECOMING MORE ELEVATED
IN NATURE WITH THE CAPE MONDAY NIGHT. KEPT POPS GOING FOR THIS
PERIOD IN THE NORTHEAST HALF OF THE AREA...CLOSEST TO THE LOW
LEVEL FRONTOGENESIS RESPONSE FIELDS.
AREA REMAINS IN WARM SECTOR AIRMASS MONDAY INTO MONDAY NIGHT PER
GFS/ECMWF/CANADIAN MODELS. 925MB TEMPERATURES SUGGEST HIGHS IN THE
LOWER TO PERHAPS MID 90S MONDAY...WITH HEAT INDEX VALUES IN THE
95 TO 101 DEGREE RANGE.
.TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE IS MEDIUM.
GFS/ECMWF SHOW SOME DIFFERENCES WITH TRENDS DURING THIS PERIOD.
THE 500MB HIGH REMAINS OVER THE KANSAS AREA DURING THIS PERIOD.
THE GFS CONTINUES TO BE FURTHER SOUTH WITH THE PASSING LOW
PRESSURE SYSTEM AND FRONTAL BOUNDARY TUESDAY INTO TUESDAY NIGHT.
DECENT MEAN LAYER CAPES OF 1000 TO 1300 J/KG WITH DECENT DEEP
LAYER SHEAR AROUND 30 TO 35 KNOTS ARE SHOWN ON GFS FORECAST
SOUNDINGS. ECMWF IS DRY WITH THE FRONTAL PASSAGE.
BOTH MODELS DO SHOW COLD FRONT DROPPING SOUTHWARD THROUGH THE AREA
TUESDAY NIGHT. CONTINUED POPS FOR TUESDAY AND TUESDAY
NIGHT IN THE NORTHEASTERN HALF OF COUNTIES...CLOSEST TO THE LOW.
AREA REMAINS IN WARM SECTOR AIRMASS ON ECMWF AND GFS...WITH 925MB
TEMPERATURES SUPPORTING ANOTHER DAY OF LOWER TO PERHAPS MID 90S
FOR HIGHS. HEAT INDEX VALUES SHOULD REACH THE 95 TO 101 RANGE
AGAIN. COUNTING WEDNESDAY...THERE WOULD BE THREE DAYS IN A ROW OF
HEAT INDEX VALUES IN THE 95 TO 100 DEGREE RANGE IN SOUTH CENTRAL
WISCONSIN. NEED FOUR IN A ROW FOR A HEAT ADVISORY. IT STILL MAY BE
NEEDED FOR MONDAY AND TUESDAY ACROSS THE AREA...IF DAILY HEAT
INDEX VALUES CONTINUE TO REMAIN AROUND OR ABOVE 100. FOR
NOW...WILL CONTINUE MENTION POTENTIAL IN HAZARDOUS WEATHER
OUTLOOK AND SPECIAL WEATHER STATEMENT.
MODEST COLD AIR ADVECTION AHEAD OF HIGH PRESSURE PUSHES INTO THE
AREA WEDNESDAY ON NORTH TO NORTHEAST WINDS...BRINGING SLIGHTLY
COOLER BUT STILL ABOVE NORMAL TEMPERATURES. HIGH PRESSURE THEN
MOVES SLOWLY SOUTHEAST THROUGH THE REGION THROUGH
THURSDAY...BRINGING QUIET WEATHER AND WARM TEMPERATURES.
WARM AIR ADVECTION AND MOISTURE ADVECTION THEN TRY TO PUSH BACK
INTO PORTIONS OF THE REGION THURSDAY NIGHT INTO FRIDAY...MORE SO
ON ECMWF THAN GFS. USED CONSENSUS POPS FOR NOW IN THIS PERIOD.
&&
.AVIATION/12Z TAFS/...ONCE PATCHY MVFR FOG AT KENW AND KUES CLEARS
THIS MORNING...LOOKING AT VFR CONDITIONS THROUGH THE DAY. LIGHT
WINDS OVER THE EAST BRINGS POTENTIAL FOR PATCHY MVFR FOG
REDEVELOPMENT AT KENW TONIGHT...BUT DEW POINT DEPRESSIONS OF 4 TO
6 DEGREES WILL LIKELY PREVENT FORMATION SO WILL LEAVE OUT FOR NOW.
&&
.MARINE...STILL LOOKS LIKE BREEZY SOUTHWEST WINDS WILL APPROACH
SMALL CRAFT ADVISORY LEVELS ON SUNDAY...ESPECIALLY CLOSE TO SHORE.
WILL MENTION POTENTIAL IN FORECAST BUT NOT ISSUE A HEADLINE AT
THIS TIME.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
SUNDAY THROUGH FRIDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
320 AM CDT SAT AUG 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SAT AUG 24 2013
MAIN SHORT TERM FORECAST CONCERN IS ON PRECIPITATION CHANCES.
CURRENTLY AS OF 08Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST
OFF THE PACIFIC NORTHWEST COAST AND OVER NEW ENGLAND...WHILE STRONG
SUBTROPICAL RIDGING DOMINATED THE CENTRAL AND SOUTHERN PLAINS.
NUMEROUS MONSOONAL SHORTWAVES WERE PRESENT ON THE WEST SIDE OF THE
RIDGE...FROM ARIZONA INTO WYOMING AND SOUTH DAKOTA. SOUTHERLY 850MB
WINDS OF 30-45 KT FROM KANSAS INTO WESTERN MN AHEAD OF THESE
SHORTWAVES ARE TRANSPORTING WARMER AND MORE MOIST AIR INTO THE UPPER
MIDWEST. PRECIPITABLE WATER VALUES HAVE CLIMBED TO 1.5-1.8 INCHES
FROM THE WESTERN PORTION OF THE FORECAST AREA INTO EASTERN PORTIONS
OF SOUTH DAKOTA AND NEBRASKA...PER SATELLITE DERIVED ESTIMATES.
MEANWHILE...850MB TEMPS HAVE CLIMBED TO 16-18C ACROSS THE FORECAST
AREA AND 22-28C ACROSS THE CENTRAL AND NORTHERN PLAINS PER RAP
ANALYSIS. THE GENERAL WARM ADVECTION PATTERN COMBINED WITH DPVA FROM
THE MONSOONAL SHORTWAVES HAS LED TO SOME SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS WYOMING...NEBRASKA AND SOUTH DAKOTA.
SYNOPTIC OVERVIEW...
THE SUBTROPICAL RIDGE OVER THE CENTRAL PLAINS IS PROGGED OVER THE
NEXT 24 HOURS TO BUILD INTO MISSOURI AND STRENGTHEN...CAUSING 500MB
HEIGHTS TO RISE ABOUT 30 METERS OVER THE FORECAST AREA. FOR THE MOST
PART IT APPEARS THE MONSOONAL SHORTWAVES COMING FROM THE ROCKIES
LOOK TO TRACK ACROSS THE DAKOTAS INTO NORTHWEST ONTARIO. THE ONE
SHORTWAVE OVER SOUTH DAKOTA MODELS SHOWED YESTERDAY TO COME ACROSS
THE FORECAST AREA TODAY IS PRETTY MUCH NON-EXISTENT IN MODELS TODAY.
NEVERTHELESS...WITH THE BUILDING RIDGING...THE WARM ADVECTION
PATTERN ACROSS THE UPPER MIDWEST WILL CONTINUE.
DETAILS...
THE QUESTION TODAY IS THE CHANCES OF PRECIPITATION NOW THAT THE
SHORTWAVE FROM SOUTH DAKOTA IS NO LONGER PRESENT. THE SIGNAL FOR
POSSIBLE SHOWER/THUNDERSTORM INITIATION ON THE EASTERN EDGE OF THE
850MB MOISTURE TRANSPORT IS STILL THERE...SUGGESTED BETWEEN 09-15Z
IN THE 24.00Z NAM/REGIONAL CANADIAN AND GFS. AFTER THAT...MODELS
HAVE DEFINITELY TRENDED DRIER FOR THE REST OF THE DAY. THIS MAKES
SENSE WITH THE BUILDING HEIGHTS. NOW THE 24.00Z NAM DOES TRY TO
GENERATE SOME ISOLATED CONVECTION OVER THE NORTHWEST HALF OF THE
AREA LATE IN THE AFTERNOON. HOWEVER...LOOKING AT SOUNDINGS THIS
SEEMS TO BE COMPLETELY TIED TO THE CONVECTIVE SCHEME AND ODD...WITH
MLCIN DROPPING FROM 70-80 J/KG TO 0 J/KG IN 1 HOUR WHILE A SUBSIDENT
PROFILE IS PRESENT. GIVEN THE CONSENSUS FOR A DRY AFTERNOON...WENT
IN THIS DIRECTION. BULK OF THE CONVECTION ALSO LOOKS TO STAY NORTH
OF THE FORECAST AREA TONIGHT WITH THE 850MB MOISTURE TRANSPORT
STREAM MOVING OVERHEAD...WHILE ITS NOSE IS FOCUSED FROM NORTHERN MN
ACROSS LAKE SUPERIOR AND UPPER MI. HAVE SHIFTED CHANCES NORTH TO
ONLY INCLUDE TAYLOR/CLARK NOW...TO ACCOUNT FOR THE DRYING
TREND...AND THESE MIGHT BE ABLE TO BE SHIFTED COMPLETELY OUT OF THE
AREA.
PARTIAL SUNSHINE TODAY COMBINED WITH 925/850MB TEMPS ABOUT 2C WARMER
SHOULD ALLOW HIGHS TO TOP OUT SIMILAR TO OR JUST SLIGHTLY WARMER
COMPARED TO YESTERDAY. CONDITIONS WILL BE A BIT MORE
MUGGY...THOUGH...AS HIGHER DEWPOINTS IN THE UPPER 60S TO LOW 70S
ADVECT IN ON INCREASING SOUTHERLY WINDS. THE SOUTHERLY BREEZE IS
EXPECTED TO PERSIST INTO TONIGHT...ALLOWING THE AFOREMENTIONED
DEWPOINTS TO SPREAD ACROSS THE FORECAST AREA. THE HIGHER DEWPOINTS
AND BREEZE SHOULD HELP KEEP TEMPERATURES UP IN THE MID 60S TO LOW
70S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 320 AM CDT SAT AUG 24 2013
HAZARDS...
1. HEAT. CONFIDENCE REMAINS HIGH THAT HEAT INDICES WILL EXCEED
ADVISORY CRITERIA BOTH MONDAY AND TUESDAY. A FEW LOCALIZED SPOTS
COULD EVEN TOUCH EXCESSIVE HEAT WARNING CRITERIA OF 105.
ADDITIONALLY...SUNDAY NOW LOOKS A LITTLE HIGHER FOR HEAT INDICES...
MORE CLOSER TO 100. GIVEN THESE CONDITIONS AS WELL AS WARM OVERNIGHT
LOWS...HAVE ISSUED A HEAT ADVISORY FOR SUNDAY THROUGH TUESDAY.
2. STORMS. THERE ARE PERIODIC STORM CHANCES THROUGHOUT THE LONG TERM
PORTION OF THE FORECAST...PARTICULARLY NORTH/EAST OF I-94.
HOWEVER...0-6KM AND 0-3 KM SHEAR VALUES ARE NEVER THAT IMPRESSIVE...
GENERALLY 25 KT OR LESS. THIS WILL KEEP HEAVY RAIN AS THE MOST
LIKELY HAZARD FROM THE STORMS.
SYNOPTIC OVERVIEW...
THE STRONG SUBTROPICAL RIDGE OVER MISSOURI TO START AT 12Z SUNDAY IS
WELL AGREED UPON BY 24.00Z GUIDANCE TO RETROGRADE WESTWARD THROUGH
THE MIDDLE OF THE WEEK. THIS RETROGRESSION IS CAUSED BY A SERIES OF
SHORTWAVE TROUGHS DROPPING DOWN THE EAST SIDE OF THE RIDGE INTO NEW
ENGLAND...THE MOST IMPRESSIVE OF WHICH CROSSES NEAR THE GREAT LAKES
REGION TUESDAY NIGHT. THE RETROGRESSION DOESNT LAST LONG...
THOUGH...AS A MORE POTENT UPPER TROUGH COMES INTO THE PACIFIC
NORTHWEST LATE IN THE WEEK...HELPING TO PUSH THE RIDGING AND ITS
WARMTH BACK EASTWARD.
PRECIPITATION DETAILS...
SUNDAY CONTINUES TO LOOK DRY WITH ALL SHORTWAVE AND 850MB MOISTURE
TRANSPORT FORCING TRACKING ACROSS LAKE SUPERIOR OR FARTHER NORTH.
THE 24.00Z NAM...HIRES ARW/NMM INITIATES SURFACE BASED CONVECTION
OVER CENTRAL MN LATE SUNDAY AFTERNOON...ALONG A SURFACE TROUGH. THE
CONVECTION THEN DROPS SOUTH TOWARDS I-90 IN THE EVENING. THESE
APPEAR TO BE STRONGLY DRIVEN BY TEMPERATURES REACHING 100F OR SO
ALONG THE TROUGH...WHICH IS THE CONVECTIVE TEMPERATURE. WHETHER OR
NOT THIS HAPPENS IS UNKNOWN...BUT JUST IN CASE DID INCLUDE 20-40
PERCENT CHANCES ALONG/NORTH OF I-90 IN THE EVENING. THESE CHANCES
CONTINUE INTO THE OVERNIGHT HOURS FOR A SECOND SCENARIO...WHERE
CONVECTION FIRES UP IN NORTHWEST WISCONSIN IN THE EVENING AND DROPS
SOUTH FOLLOWING CORFIDI VECTORS. THIS IS PRESENTED BY THE 24.00Z
GFS/ECMWF. IT SHOULD BE NOTED...THOUGH...THE 24.00Z CANADIAN/UKMET
ARE DRY...KEEPING ALL CONVECTION TO THE NORTH OF THE AREA. ALSO
INTERESTING TO NOTE IS THAT THE NAM...GFS AND ECMWF ARE ALL DRY
MONDAY MORNING...SUGGESTING CONVECTION WEAKENS AS IT RUNS INTO THE
CAPPING OVER THE AREA.
ALL MODELS INDICATE THAT AN OUTFLOW BOUNDARY/WARM FRONT SHOULD BE
LOCATED SOUTH OF THE OVERNIGHT CONVECTION...SETTING UP NEAR I-94 FOR
MONDAY AFTERNOON. 24.00Z GFS/ECMWF BOTH FIRE SOME CONVECTION ALONG
THIS BOUNDARY WHICH WOULD APPEAR POSSIBLE GIVEN THE HOT AND HUMID
AIRMASS IMPINGING ON IT FROM THE SOUTHWEST. THEREFORE...CARRIED 20
PERCENT CHANCES ALONG/NORTH OF I-94 FOR THE AFTERNOON. THESE CHANCES
PERSIST THROUGH MONDAY NIGHT AND TUESDAY...AIDED BY INCREASING 850MB
MOISTURE TRANSPORT AHEAD OF A MORE SIGNIFICANT SHORTWAVE TRACKING
ACROSS THE DAKOTAS...INTO NW MINNESOTA AND LAKE SUPERIOR. GREATER
CHANCES FOR CONVECTION MONDAY NIGHT AND TUESDAY SHOULD STAY OFF TO
THE NORTH AND NORTHEAST CLOSER TO THAT SHORTWAVE TRACK.
A COLD FRONT IS PROGGED TO DROP THROUGH TUESDAY NIGHT. PLENTY OF
CAPPING AHEAD OF THE FRONT SHOULD RESTRICT SURFACE BASED CONVECTION
ON IT...WITH DRY CONDITIONS LIKELY IN ITS WAKE FOR WEDNESDAY INTO
THURSDAY. CHANCES OF SHOWERS AND STORMS RETURN THURSDAY NIGHT
THROUGH FRIDAY NIGHT AS THE FRONT GRADUALLY RETURNS BACK
NORTHEASTWARD AS A WARM FRONT.
TEMPERATURE DETAILS...
SUNDAY...WITH PLENTY OF SUN...BREEZY SOUTHWEST WINDS AND 925 MB
TEMPS CLIMBING TO 26-28C...HIGH TEMPS SHOULD EASILY TOP OUT IN THE
UPPER 80S TO LOW 90S. A FEW VALLEY LOCATIONS COULD EVEN HIT THE MID
90S. WITH DEWPOINTS LIKELY IN THE UPPER 60S TO LOW 70S...PEAK HEAT
INDICES OF 95 TO 100 SHOULD BE COMMON...HIGHEST OVER THE NORTHWEST
HALF OF THE FORECAST AREA.
MONDAY...INDICATIONS ARE THAT THERE SHOULD STILL BE PLENTY OF
SUN...EVEN IF THERE IS ANY DISSIPATING MORNING CONVECTION OR
AFTERNOON DEVELOPMENT. WITH 925MB TEMPS CLIMBING FURTHER TO AROUND
28C TO POSSIBLY EVEN 30C PER GFS...HIGHS IN THE LOW TO MID 90S ARE
LIKELY. COMBINED WITH DEWPOINTS STAYING ABOUT THE SAME RESULTS IN
PEAK HEAT INDICES OF 100 TO 105.
TUESDAY...WILL HAVE TO WATCH THIS DAY CLOSELY AS IT COULD BE THE
HOTTEST OF THE WEEK. AHEAD OF THE APPROACHING COLD FRONT...A
SOUTHWEST TO WEST WIND PUSH OF THE HOT PLAINS AIR ADVECTS OVER THE
AREA. 925MB TEMPS OF 29-31C PER ECMWF/GFS ARE PROGGED WHICH COULD
PUSH TEMPS TOWARDS 100F. ONLY CONCERN IS THE LOWER SUN ANGLE
COMPARED TO SAY JULY. RAISED HIGHS A COUPLE DEGREES BUT MORE
INCREASES MAY BE NEEDED. NEW FORECAST HIGHS ARE AT RECORDS. HEAT
INDICES AGAIN LOOK TO PEAK OUT AT 100-105.
A COOL DOWN BUT STILL STAYING WELL ABOVE NORMAL IS PROGGED FOR
WEDNESDAY AND THURSDAY. FRIDAY IS A BIT MORE UNCERTAIN WITH THE
24.00Z ECMWF SHOWING ANOTHER SHORTWAVE DROPPING THROUGH THE GREAT
LAKES...SLOWING DOWN THE EASTWARD MOVEMENT OF THE UPPER RIDGE.
FRIDAY PREVIOUSLY LOOKED LIKE WHEN THE HEAT WOULD RETURN. HEAT STILL
ON TARGET TO RETURN DURING LABOR DAY WEEKEND...HOWEVER.
LEANED TOWARDS THE WARM SIDE OF RAW MODEL GUIDANCE FOR LOWS SUNDAY
NIGHT AND MONDAY NIGHT. CONSENSUS OF MODEL GUIDANCE USED THEREAFTER.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 1115 PM CDT FRI AUG 23 2013
A WARM FRONT WILL GRADUALLY LIFT NORTHEAST ACROSS THE REGION
OVERNIGHT/EARLY SAT. NOT A BIG SHIFT IN THE WINDS...AND NOT
MUCH CONVERGENCE AROUND IT. HOWEVER...MESO MODELS POINT TO SOME LOW
LEVEL WARM AIR/ISENTROPIC CONVERGENCE WITH IT...ALTHOUGH NOT A WHOLE
LOT OF SATURATION THROUGH THE COLUMN PER BUFKIT SOUNDINGS. SEE SOME
SCT-BKN CLOUDS...BUT NOT MUCH IN THE WAY OF PCPN AT THIS TIME. THAT
SAID...THE HRRR CONTINUES TO SUGGEST A THIN LINE OF SCT-BKN -SHRA
COULD TRACK ACROSS KLSE NEAR 12Z. CHANCES LOOK A LITTLE BIT BETTER
BY LATE MORNING/AFTERNOON WITH AN INCREASE IN THE LOW LEVEL
CONVERGENCE/WARM AIR ADVECTION. SATURATION STILL NOT
IMPRESSIVE...BUT MIGHT BE ENOUGH FOR SCT SHRA/TS. OVERALL...BEST
SHRA/TS WILL LIKELY HOLD NORTH OF KRST/KLSE THROUGH SAT NIGHT.
HIGH PRESSURE EXITS EAST TONIGHT...WITH A TIGHTENING PRESSURE
GRADIENT WORKING IN OVERNIGHT. SFC WINDS SHOULD NOT LIGHTEN UP TOO
MUCH AS A RESULT...WITH BUFKIT SOUNDINGS INDICATING GOOD STIRRING BY
200 FT. THUS...WINDS WILL BE THE MAIN LIMITING FACTOR TO ANY FOG
POTENTIAL. EXPECT HIGHER GUSTS SAT AFTERNOON AS WINDS BEGIN TO MIX.
&&
.CLIMATE...
ISSUED AT 307 PM CDT FRI AUG 23 2013
HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR
DAY WEEKEND GIVEN THE UPCOMING INCREASE IN HEAT. FOR MORE CLIMATE
INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ017-029-032>034-041>044-053>055-061.
MN...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-086>088-094>096.
IA...HEAT ADVISORY FROM NOON SUNDAY TO MIDNIGHT CDT TUESDAY NIGHT FOR
IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RIECK
CLIMATE...DAS/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1115 PM CDT FRI AUG 23 2013
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 307 PM CDT FRI AUG 23 2013
MAIN SHORT TERM CONCERN IS SHOWER/THUNDERSTORM CHANCES.
WATER VAPOR/RAP 500MB ANALYSIS THIS AFTERNOON SHOWING A PERSISTENT
DEEP TROUGHS OF LOW PRESSURE ALONG THE WEST AND EAST COASTS WHILE
AMPLIFYING RIDGE WAS BUDGING SLOWLY FROM THE INTERMOUNTAIN WEST INTO
THE CENTRAL CONUS. AT THE SURFACE...HIGH PRESSURE WAS CENTERED OVER
THE GREAT LAKES REGION. INCREASING SOUTH/SOUTHEAST FLOW WAS NOTED
ACROSS OUR AREA ON THE BACKSIDE OF THE HIGH WITH TEMPERATURES IN THE
UPPER 70S TO LOWER 80S.
CURRENTLY WATCHING WATER VAPOR CLOSELY GIVEN MONSOONAL FLOW TAP INTO
THE INTERMOUNTAIN WEST WITH EMBEDDED SHORTWAVE TROUGH/MCV ACTIVITY.
ONE SUCH WAVE WAS NOTED MOVING OUT OF WY INTO SD AT THIS TIME. THIS
WAVE IS EXPECTED TO PROPAGATE EASTWARD TO THE AREA LATE TONIGHT INTO
SATURDAY AND INTERACT WITH AN APPROACHING WARM FRONT. ALSO OF NOTE
WILL BE EASTERN PERIPHERY OF INCREASING ISENTROPIC LIFT AND MOISTURE
TRANSPORT IMPINGING ON THE AREA. BOTTOM LINE WILL BE INCREASING
MID-LEVEL CLOUD COVER ALONG WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE MISSISSIPPI RIVER AFTER MIDNIGHT...
AND THEN ACROSS THE REST OF THE AREA SATURDAY. NAM HAS MLCAPE VALUES
IN THE 1000-1500J/KG RANGE ACROSS WESTERN WI INTO SOUTHEAST
MN/NORTHEAST IA WITH 1-6KM BULK SHEAR VALUES IN THE 20-25KT RANGE.
GIVEN THIS FACT...WILL HAVE TO WATCH FOR AN ISOLATED VIGOROUS STORM
WITH HEAVIER DOWNPOUR/SMALL HAIL THREAT. OTHERWISE...LOWS
TONIGHT ARE EXPECTED TO BOTTOM OUT IN THE UPPER 50S TO THE MIDDLE
60S WITH HIGHS SATURDAY IN THE 80-85 DEGREE RANGE.
APPEARS BULK OF SHOWER/THUNDERSTORM ACTIVITY SHOULD PUSH NORTHEAST
OF THE AREA WIT THE PASSAGE OF THE WARM FRONT. HOWEVER...MOISTURE
TRANSPORT VECTORS STILL FOCUS ACROSS PORTION OF THE AREA MAINLY
NORTH OF I-94 THROUGH THE NIGHT. AS SUCH...KEPT A 20-30 PERCENT
PROBABILITY OF SHOWERS/THUNDERSTORMS ACROSS THAT AREA. WITH
INCREASING HUMIDITY AND GETTING INTO THE WARM SECTOR...LOWS SATURDAY
NIGHT EXPECTED TO BOTTOM OUT IN THE UPPER 60S TO LOWER 70S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 307 PM CDT FRI AUG 23 2013
MAIN TOPIC OF CONCERN THROUGH THE LONG TERM PERIOD WILL BE
INCREASING HEAT WITH BUILDING MID/UPPER LEVEL RIDGE OVER THE CENTRAL
CONUS AND UPPER MISSISSIPPI RIVER VALLEY REGION. HOWEVER...MAY SEE A
COUPLE WEAK TROUGH PASSAGES WITH SHOWER/THUNDERSTORM CHANCES. AS A
RESULT...NOT OVERLY CONFIDENT ON HEAT HAZARD HEADLINE AREA PLACEMENT
AT THIS TIME. IT APPEARS AT THIS TIME...THE HIGHEST LIKELIHOOD FOR
HEAT HAZARD HEADLINES WOULD BE FROM I-94 AND SOUTH...WHICH IS
ENTRENCHED MORE INTO THE RIDGE. AREAS NORTH AND EAST OF THIS WILL BE
SUSCEPTIBLE TO THESE WEAK TROUGH PASSAGES AND POTENTIAL FOR
THUNDERSTORM COMPLEXES ROLLING THROUGH. IT APPEARS HEAT INDEX
CRITERIA FOR HEADLINES //100 DEGREES +// WILL BE MET MONDAY AND
TUESDAY AFTERNOONS AND EARLY EVENINGS. AS A RESULT...WILL PROBABLY
HOLD OFF ON ANY HEAT HEADLINE ISSUANCE FOR NOW.
TEMPERATURE/HEAT DETAILS...
ECMWF AND GFS BEGIN TO HEAT THINGS UP ON SUNDAY. GOOD
MIXING/SOUTHWEST BREEZE WILL COMBINE WITH 925 TEMPERATURES IN THE
27-29C RANGE FOR HIGHS IN THE 90-95F DEGREE RANGE. GOOD MIXING
SHOULD DECREASE HUMIDITY SOMEWHAT WITH HEAT INDICES TOPPING OFF IN
THE 95-100 DEGREE RANGE.
HIGHER HUMIDITY WITH TEMPERATURES TOPPING OFF IN THE LOWER/MIDDLE
90S MONDAY AND TUESDAY WILL PUSH HEAT INDICES INTO THE 100-105
DEGREE RANGE...ESPECIALLY SOUTHWEST OF I-94. THESE DAYS WILL NEED AT
LEAST A HEAT ADVISORY.
WEDNESDAY/THURSDAY/FRIDAY LOOKING A BIT MORE UNCERTAIN WITH THE
23.12Z ECMWF/GFS SHOWING COOLING 925MB TEMPERATURES WITH TROUGH
PASSAGE THROUGH PARTS OF THE AREA/GREAT LAKES REGION. THIS WOULD
KEEP THE AREA BELOW HEAT ADVISORY CRITERIA WITH THE POSSIBLE
EXCEPTION OF NORTHEAST IA INTO FAR SOUTHWEST WI WEDNESDAY AFTERNOON.
MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 1115 PM CDT FRI AUG 23 2013
A WARM FRONT WILL GRADUALLY LIFT NORTHEAST ACROSS THE REGION
OVERNIGHT/EARLY SAT. NOT A BIG SHIFT IN THE WINDS...AND NOT
MUCH CONVERGENCE AROUND IT. HOWEVER...MESO MODELS POINT TO SOME LOW
LEVEL WARM AIR/ISENTROPIC CONVERGENCE WITH IT...ALTHOUGH NOT A WHOLE
LOT OF SATURATION THROUGH THE COLUMN PER BUFKIT SOUNDINGS. SEE SOME
SCT-BKN CLOUDS...BUT NOT MUCH IN THE WAY OF PCPN AT THIS TIME. THAT
SAID...THE HRRR CONTINUES TO SUGGEST A THIN LINE OF SCT-BKN -SHRA
COULD TRACK ACROSS KLSE NEAR 12Z. CHANCES LOOK A LITTLE BIT BETTER
BY LATE MORNING/AFTERNOON WITH AN INCREASE IN THE LOW LEVEL
CONVERGENCE/WARM AIR ADVECTION. SATURATION STILL NOT
IMPRESSIVE...BUT MIGHT BE ENOUGH FOR SCT SHRA/TS. OVERALL...BEST
SHRA/TS WILL LIKELY HOLD NORTH OF KRST/KLSE THROUGH SAT NIGHT.
HIGH PRESSURE EXITS EAST TONIGHT...WITH A TIGHTENING PRESSURE
GRADIENT WORKING IN OVERNIGHT. SFC WINDS SHOULD NOT LIGHTEN UP TOO
MUCH AS A RESULT...WITH BUFKIT SOUNDINGS INDICATING GOOD STIRRING BY
200 FT. THUS...WINDS WILL BE THE MAIN LIMITING FACTOR TO ANY FOG
POTENTIAL. EXPECT HIGHER GUSTS SAT AFTERNOON AS WINDS BEGIN TO MIX.
&&
.CLIMATE...
ISSUED AT 307 PM CDT FRI AUG 23 2013
HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR
DAY WEEKEND GIVEN THE UPCOMING INCREASE IN HEAT. FOR MORE CLIMATE
INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK
CLIMATE......DAS/AJ
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
945 PM PDT SUN AUG 25 2013
.SYNOPSIS...
TROPICAL MOISTURE WILL SPREAD NORTH AND WESTWARD THROUGH MONDAY
EVENING. THIS WILL BRING PERIODS OF HEAVY RAIN SHOWERS AND
THUNDERSTORMS...PARTICULARLY OVER THE MOUNTAINS AND DESERTS. HOWEVER
THERE WILL ALSO BE A CHANCE OF THUNDERSTORMS WITH SIGNIFICANT
RAINFALL WEST OF THE MOUNTAINS. A FLASH FLOOD WATCH IS IN EFFECT FOR
MOST AREAS UNTIL MIDNIGHT MONDAY NIGHT. SHOWERS SHOULD DECREASE
TUESDAY...BUT THE THREAT OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS WILL CONTINUE THROUGH THIS WEEK.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
HEAVY RAINFALL/THUNDERSTORMS THIS AFTERNOON AND EVENING...MORE OR
LESS EAST OF A LINE FROM BIG BEAR TO MOUNT SAN JACINTO TO LAKE
HENSHAW THEN SOUTH TO TECATE. RAINFALL AMOUNTS WERE OVER 2 INCHES
AT MANY MOUNTAIN/DESERT LOCATIONS WITH CLOSE TO 4 INCHES BEING
REPORTED BETWEEN COYOTE CREEK AND TORO PEAK. MANY ROADWAYS
FLOODED/WASHED OUT AND REPORTS OF MOTORISTS TRAPPED IN VEHICLES. SEE
LOCAL STORM REPORT SUMMARY ISSUED AT 841 PM PDT...LSRSGX.
SATELLITE IMAGERY...THE HOURLY HRRR MODEL HAS BEEN CONSISTENTLY
SHOWING...ALONG WITH BOTH THE 18Z AND 26/00Z RUNS OF THE GFS
MODEL...NEXT SLUG OF MOISTURE/PRECIPITATION MOVING INTO EASTERN SAN
DIEGO COUNTY NOW AND BEING TRANSPORTED NORTHWESTWARD ACROSS
MOUNTAINS DURING THE NEXT 6 HOURS...REACHING COASTLINE AND MOVING
OUT TO SEA BETWEEN 0200-0500. THE 26/00Z NAM RUN KEEPS THE MOISTURE
EAST OF THE MOUNTAINS. WITH GFS MODEL BEING MOST CONSISTENT THIS
PAST WEEK...WILL STAY WITH IT.
THE FORECAST WAS BASED ON THIS SO ONLY HAD TO MAKE MINOR TWEAKS TO
SHOW HIGHER POPS...EXPAND THE FLASH FLOOD WATCH TO START 8 AM OVER
SAN DIEGO COUNTY INLAND VALLEYS AND GO UNTIL MIDNIGHT MONDAY
NIGHT...AS WELL AS EXTEND UNTIL MIDNIGHT MONDAY NIGHT FOR THE OTHER
ZONES.
FOR LATE MONDAY NIGHT THROUGH SATURDAY...
EXCERPTS FROM AFTERNOON DISCUSSION...
THE NAM12 CARRIES AN UPPER CIRCULATION FEATURE NORTH...OFF THE COAST
MON NIGHT/TUE MORNING. THERE IS SOME INSTABILITY ASSOCIATED WITH
THIS AND PWS REMAIN IN EXCESS OF 1.5 INCHES...SO THERE IS A CHANCE
OF SOME NOCTURNAL CONVECTION OVER THE ENTIRE CWA...BUT FORCING LOOKS
LIMITED FOR WIDESPREAD DEVELOPMENT. THE MARINE LAYER SHOULD REMAIN
QUITE SHALLOW AND DISORGANIZED...MAINLY OVER THE COASTAL WATERS.
LITTLE CHANGE IN THE UPPER AIR PATTERN THIS WEEK WITH THE LARGE
SUBTROPICAL HIGH CENTERED OVER THE SOUTHERN PLAINS...AND A LONG WAVE
TROUGH PARKED OFF THE WEST COAST OF CANADA AND PACNW. THIS KEEPS
SUFFICIENT MONSOONAL MOISTURE OVER THE AREA TO FEED AFTERNOON AND
EVENING CONVECTION IN THE MTNS/DESERTS. OTHERWISE...SEASONALLY WARM
WITH A SHALLOW MARINE LAYER SUPPORTING CAMEO APPEARANCES OF
NOCTURNAL FOG/LOW CLOUDS ALONG THE COAST AT TIMES.
&&
.HYDROLOGY...
ISSUED AN UNSCHEDULED QPSSGX.
ADDITIONAL STORM TOTALS REMAINDER MONDAY THROUGH TUESDAY...
MOUNTAINS 2-4 INCHES...
DESERTS...1-2 INCHES...
WEST OF A INTERSTATE 215/HIGHWAY 67/HIGHWAY 125TO COASTAL
FOOTHILLS...0.50 TO 1.75 INCHES...
SANTA ANA MOUNTAINS/FOOTHILLS /REMAINDER OF INLAND EMPIRE/AND WEST
TO INTERSTATE 5...0.25 TO 0.50 INCHES...
COASTAL SECTIONS...0.10 TO 0.25 INCHES.
ABOVE NUMBERS REFLECT AVERAGE AREAL RAINFALL COVERAGE AND INDIVIDUAL
LOCATIONS WILL LIKELY HAVE MUCH HEAVIER AMOUNT UNDER SLOW MOVING OR
REPEAT THUNDERSTORM CELLS. EACH THUNDERSTORM COULD EASILY DUMP
OVER TWO INCHES OF RAIN PER HOUR...AND IF SEVERAL THUNDERSTORMS HIT
THE SAME LOCATION DURING A 6 HOUR PERIOD...YOU CAN DO THE MATH. THIS
IS A MOIST MARITIME TROPICAL AIR MASS SO THINK FLORIDA OR ANY OF THE
GULF COAST STATES AND NOT THE NORMAL MODIFIED CONTINENTAL AIR MASS
THAT WE USUALLY DEAL WITH IN MONSOON EVENTS.
&&
.AVIATION...
260300Z...COAST/VALLEYS...FORECAST CONFIDENCE THIS CYCLE...MODERATE.
AREAS OF LOW CLOUDS AND FOG WILL LIKELY RETURN TO THE COASTAL AREAS
THIS EVENING AND MAY INTERMITTENTLY IMPACT THE COASTAL TAF SITES
AFTER 06Z MON WITH BKN-OVC CIGS AROUND 500 TO 700 FT MSL AND VIS
1-3SM LOCALLY BLO 1SM. LOW CLOUDS AND FOG SHOULD CLEAR BY 261800Z
MON. OTHERWISE...SCT CLOUDS AOA 10000 FT WITH UNRESTRICTED VIS
THROUGH THIS EVENING. ISOLD THUNDERSTORMS AND SHOWERS ARE POSSIBLE
TONIGHT THROUGH MON AS THE MOISTURE FR0M THE REMNANTS OF IVO SURGE A
BIT FURTHER WEST.
MTNS/DESERTS...SCT TSTMS WITH SCT-BKN CLOUDS LAYERED FROM 8000 FT TO
35000 FT. VSBY MAY BE LIMITED FOR SHORT PERIODS NEAR THUNDERSTORMS
DUE TO HEAVY RAIN OR BLOWING DUST FROM GUSTY WINDS.
&&
.MARINE...
ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE OVER THE COASTAL
WATERS TONIGHT AND MONDAY. THESE STORMS COULD PRODUCE LOWER
VISIBILITY DUE TO HEAVY RAIN...CLOUD TO WATER LIGHTNING...SMALL HAIL
AND LOCALLY GUSTY WINDS WITH ROUGH SEAS.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR THE APPLE AND
LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE COUNTY
MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO
COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.
FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR THE SAN BERNARDINO
AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE...SANTA ANA
MOUNTAINS AND FOOTHILLS.
FLASH FLOOD WATCH FROM 8 AM PDT MONDAY THROUGH MONDAY EVENING
FOR THE SAN DIEGO COUNTY VALLEYS.
PZ...NONE.
&&
$$
PUBLIC/FIRE WEATHER...BALFOUR
AVIATION/MARINE...JJT/PIERCE
SHORT TERM WARNINGS...MAXWELL/JJT
GRAPHICS...BA
AREA FORECAST DISCUSSION
NWS GOODLAND KS
245 AM MDT MON AUG 26 2013
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 243 AM MDT MON AUG 26 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW LARGE H5 598DM RIDGE
STILL IN PLACE ACROSS THE CENTRAL CONUS. WHILE THERE IS WEAK
ENERGY ROTATING AROUND THE WEST SIDE OF THE RIDGE THAT CONTINUES TO
INITIATE SHOWER/THUNDERSTORM ACTIVITY OVER THE MOUNTAINS...BEYOND
HIGH CLOUDS MOVING ACROSS THE WESTERN PART OF OUR CWA THESE WEAK
WAVES WILL NOT HAVE ANY INFLUENCE ON OUR WEATHER LOCALLY. WITH
THIS VERY STAGNANT PATTERN IN PLACE FORECAST FOCUS CONTINUES TO
BE ON HOT TEMPERATURES AND MARGINAL FIRE WEATHER CONDITIONS.
TIGHT GRADIENT IS STILL IN PLACE ACROSS OUR CWA ON EASTER EDGE OF
TEE TROUGH...HOWEVER THE MAIN TROUGH AXIS IS BEGINNING OT SHIFT
CLOSER TO THE KS/CO BORDER WHICH SHOULD HELP RELAX THE GRADIENT
ACROSS THE NW HALF OF OUR CWA. AS WOULD BE EXPECTED WITH LESS
GRADIENT IN THE NW PART OF OUR CWA...SHORT RANGE MODELS ARE
BACKING OFF ON WINDS ACROSS THE WEST...WITH GUSTY WINDS MAINLY
ACROSS OUR EASTERN CWA. LOWEST RH VALUES SHOULD BE ACROSS THE WEST
AS HAS BEEN THE CASE THE LAST FEW DAYS...AND ARE ALREADY MARGINAL
FOR RFW. THE CHANCE FOR RH/WIND CROSSOVER IS VERY LOW...SO FIRE
WEATHER HIGHLIGHT WILL NOT BE NECESSARY.
REGARDING TEMPERATURES...NAM/GFS/ECMWF ALL SHOW VERY SIMILAR
AIR MASS IN PLACE THROUGH TUESDAY WHICH MEAN THERE SHOULDNT BE A
LOT OF VARIANCE FROM UPPER 90S/LOW 100S. BETTER MIXING COULD
RESULT IN NEAR RECORD HIGHS AT A FEW LOCATIONS. I DECIDED TO KEEP
ONGOING FORECAST WITHIN A DEGREE OR TWO OF PERSISTENCE WITH LITTLE
EXPECTED TO CHANGE. THROUGH TUESDAY NIGHT. BY WEDNESDAY A
SHORTWAVE TROUGH/MID LEVEL VORTICITY MAX WILL ROTATE FROM THE
SOUTHERN PLAINS AND ACROSS WESTERN KANSAS OUT OF THE SOUTH. WHILE
LARGE SCALE ASCENT AND ELEVATED INSTABILITY ASSOCIATED WITH A
MID LEVEL COLD POOL WILL MOVE OVER THE CWA...THERE IS A
SIGNIFICANTLY DRY AIR MASS IN PLACE. BEYOND AN INCREASE IN CLOUDS I
AM NOT ANTICIPATING ANY PRECIP WITH THIS FEATURE. THIS WILL HELP
REDUCE TEMPS OVER THE CWA BY ABOUT 5-7F FOR MOST LOCATIONS...WHICH
IS A SMALL CONCESSION SINCE THIS IS STILL WELL ABOVE NORMAL.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 243 AM MDT MON AUG 26 2013
THE UPPER LEVEL RIDGE WILL PERSIST THROUGH THE EXTENDED PERIOD. THE
WARMEST 850 MB TEMPERATURES WILL BE ON FRIDAY AND SATURDAY RESULTING
IN HIGH TEMPERATURES IN THE UPPER 90S TO NEAR 100 DEGREES BOTH DAYS.
DIFFERENCES IN MEDIUM RANGE MODELS EMERGE OVER THE WEEKEND WITH THE
CHARACTER AND POSITION OF THE UPPER LEVEL RIDGE AND THE EASTWARD
PROGRESSION OF PACIFIC NORTHWEST TROUGH. GFS ENSEMBLE MEAN IS THE
MOST PROGRESSIVE SHIFTING BOTH FEATURES EASTWARD AND PLACING THE
AREA IN SOUTHWESTERLY FLOW ALOFT. IN CONTRAST ECMWF HOLDS THE RIDGE
OVER THE AREA WITH A SLIGHT DEAMPLIFICATION AS A SHORTWAVE TROUGH
MOVES EASTWARD ACROSS THE NORTHERN PLAINS. IN EITHER SCENARIO...A
GENERALLY DRY PATTERN WITH ABOVE NORMAL TEMPERATURES ARE LIKELY TO
PERSIST THROUGH THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1145 PM MDT SUN AUG 25 2013
VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD WITH GUSTY
SOUTH WINDS BETWEEN 15Z AND 02Z ON MONDAY.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BRB
AVIATION...LOCKHART
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1220 AM CDT MON AUG 26 2013
.SYNOPSIS...
ISSUED AT 359 PM CDT SUN AUG 25 2013
NOT MUCH HAS CHANGED IN THE UPPER LEVELS IN THE LAST 24 HRS...WITH A
598 DM HIGH CENTERED OVER MISSOURI THAT IS STILL FLANKED BY TROUGHS
ON EITHER COAST OF NOAM. ACROSS THE ROCKIES...WATER VAPOR IMAGERY IS
SHOWING A TROPICAL MOISTURE PLUME FROM THE REMNANTS OF AN ERN
PACIFIC TROPICAL SYSTEM CURRENTLY OVER THE BAJA PENINSULA THAT IS
NOW WORKING ITS WAY AROUND THE WRN PERIPHERY OF THE MISSOURI HIGHS
AND ALREADY MOVING UP INTO WYOMING...LIKELY REACHING THE UPPER MS
VALLEY MONDAY.
AT THE SFC A TROUGH OF LOW PRESSURE WAS SITUATED FROM CENTRAL SODAK
NE TO NEAR INL. STRONG PRESSURE GRADIENT IS STILL IN PLACE...WITH
BREEZY SOUTHWEST WINDS CONTINUING. WITH TEMPS IN THE LOW TO MID 90S
AND DEWPS IN THE LOW TO MID 70S...STARTING TO SEE HEAT INDICES CLIMB
TO OVER 100 DEGREES...WITH VALUES OF MLCAPE UP SAFELY IN THE HEALTHY
RANGE BETWEEN 3500 AND 6000 J/KG.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 359 PM CDT SUN AUG 25 2013
AS CAN BE IMAGINED...WITH A CAPPED...WEAKLY FORCED...HIGH CAPE
ENVIRONMENT...CONFIDENCE IS STILL QUITE LOW ON WHERE/IF CONVECTION
WILL FIRE LATER THIS EVENING. ONE THING IS FOR SURE...PRESENCE OF
ENOUGH INSTABILITY IS NOT AN ISSUE!
WHEN LOOKING AT THE SPC MESO ANALYSIS AND SATELLITE ALONG
WITH A FEW INSTABILITY/MOISTURE TRANSPORT FIELDS FROM THE
DETERMINISTIC MODELS YOU CAN GET A SENSE OF HOW THINGS SHOULD TRY TO
UNFOLD THIS EVENING. FROM THE MESO ANALYSIS SIDE OF THINGS...THERE
IS A GRADIENT IN THE MLCAPE FIELD ACROSS CENTRAL MN...WHICH IS
COINCIDENT WITH THE NRN EDGE OF THE STEEPER MID LEVEL LAPSE RATES
ASSOCIATED WITH AN EML AND STRONGER CAPPING. JUST NORTH OF THE
MLCAPE GRADIENT...THE 20Z ANALYSIS SHOWS H7 DEWPOINTS BETTER THAN
10C ACROSS THE SRN END OF THE DLH/FGF FORECAST AREAS. WITHIN THIS
ZONE OF HIGHER MOISTURE AT H7 MOISTURE...A SHALLOW CU FIELD HAS
DEVELOPED BENEATH A FEW BITS OF ACCUS THAT STRETCH FROM AROUND
FERGUS FALLS OVER TOWARD DULUTH. BEST GUESS RIGHT NOW IS THAT IF
STORMS ARE TO DEVELOP...IT WILL BE WITHIN THIS ZONE...LIKELY CLOSER
TO 00Z.
IN ADDITION...MODELS SHOW THE LLJ AND ASSOCIATED MOISTURE ADVECTION
VEERING SOME AND SAGGING SOUTH THROUGH THE NIGHT. THE AREA OF CLOUDS
REFERENCED ABOVE ALSO SITS ON THE NRN EDGE OF THE MAIN MOISTURE
TRANSPORT PLUME AT H85...WHICH MOST GUIDANCE SHOW COMING DOWN TO
ABOUT I-94 OVERNIGHT. IF SOMETHING CAN GET GOING...THE PRESENCE OF
THE LLJ SHOULD KEEP THE ACTIVITY GOING THROUGH MUCH OF THE NIGHT.
WITH THE RAP AND MOST OTHER MODELS SHOWING THE STRONGEST MOISTURE
TRANSPORT IN THE H85-H7 LAYER RESIDING OVER ERN MN/WRN
WI...CONTINUED TO ADVERTISE LIKELY POPS IN ERN AREAS...THAT TAIL OFF
TO LOW CHANCE POPS IN THE WEST FOR TONIGHT.
FROM THE SEVERE END OF THINGS...AN ENVIRONMENT ASSOCIATED WITH HIGH
MOISTURE CONTENT /PWATS CURRENT NEAR 2 INCHES/...DEEP MELTING
LAYERS...AND WEAK SHEAR MEANS LARGE HAIL WILL BE TOUGH TO COME BY.
HOWEVER...VALUES OF DCAPE UP AROUND 1500 J/KG INDICATES THE WIND
POTENTIAL IS CERTAINLY STILL THERE IF WE CAN GET ANY DEEP MOIST
CONVECTION GOING.
WHAT HAPPENS TONIGHT WILL GO A LONG WAY IN DETERMINING WHERE ANY
POTENTIAL CONVECTION CAN FIRE UP MONDAY AFTERNOON. THE QUESTION FOR
TOMORROW IS FAR SOUTH CAN THE BOUNDARY SLOWLY HEADING FOR CENTRAL MN
MAKE IT TONIGHT. IF WE DO SEE A GOOD AMOUNT OF CONVECTION
OVERNIGHT...THEN THERE IS A GOOD CHANCE THAT THE BOUNDARY CAN MAKE
IT DOWN TO ABOUT I-94. IF WE DO NOT SEE MUCH CONVECTION
TONIGHT...THEN IN ALL LIKELIHOOD...THE BOUNDARY WILL REMAIN NORTH OF
THE MPX AREA...WITH ANOTHER DAY OF CAPED SUNNY SKIES ENSUING. THE
NAM/SREF WOULD SUPPORT THE SRN IDEA...WHILE THE GFS/ECMWF/GEM GO
NORTH. FOR NOW WENT WITH CHANCE POPS AFTER 21Z FOR AREAS NORTH OF
I-94. FROM THE SEVERE PERSPECTIVE...ABOUT THE ONLY THING DIFFERENT
ABOUT MONDAY COMPARED TO TODAY IS THAT THE BELT OF STRONGER
WESTERLIES WILL HAVE SAGGED SOUTH A BIT MORE...INCREASING THE AMOUNT
OF DEEP LAYER SHEAR...WHICH WILL MAKE THE RISK OF LARGE HAIL A BIT
HIGHER OWING TO THE CHANCE OF GETTING AT LEAST WEAK SUPERCELL
STRUCTURES GOING.
LAST STOP IS WITH TEMPERATURES. OVERNIGHT...EXPECT CENTRAL MN TO
COOL A FEW DEGREES MORE THAN THEY DID LAST NIGHT AS THE PRESSURE
GRADIENT WEAKENS...ALLOWING FOR SOME RADIATIONAL COOLING TONIGHT.
STILL...WITH DEWPS AROUND 70...MOST PLACES SHOULD STILL STAY ABOVE
THAT MARK. FOR THE TWIN CITIES AND PLACES FARTHER SOUTH/EAST...WINDS
WILL REMAIN IN PLACE /THOUGH NOT AS STRONG AS LAST NIGHT/...WHICH
WILL KEEP SOME FORM OF MIXING GOING AND ONCE AGAIN MAKE IT A
STRUGGLE FOR A LOT OF PLACES TO DROP BELOW 80 WITHOUT THE HELP OF
RAIN.
FOR HIGHS TOMORROW...925-850 MB TEMPS ACTUALLY INCREASE A DEGREE OR
TWO AS COMPARED TO TODAY...WHICH WOULD THEORETICALLY MEAN WE COULD
GET A DEGREE OR TWO WARMER. HOWEVER...THERE IS THE POTENTIAL FOR A
BIG BUST WITH HIGHS TOMORROW DEPENDING ON WHAT HAPPENS WITH STORMS
TONIGHT. IF WE DO END UP SEEING FAIRLY WIDESPREAD AND ROBUST
CONVECTION OVERNIGHT...THIS WOULD LIKELY LEAVE BEHIND PLENTY OF
DEBRIS COLD COVER...PUTTING A DAMPER ON TEMPERATURES. THE HIRES NMM
EAST DOES EXACTLY THAT WITH CONVECTION OVERNIGHT. THE RESULTING
CLOUD COVER IT GENERATED FOR THE NEXT DAY RESULTED IN IT ONLY
GENERATING HIGHS IN THE MID/UPPER 80S. AT THE OTHER END OF THE
SCALE...A NIGHT OF LITTLE CONVECTION WILL RESULT IN ANOTHER DAY OF
LOTS OF SUN. IN THAT CASE...THEN HIGHS TOMORROW WOULD BE A DEGREE OR
TWO WARMER THAN TODAY...WITH HIGHS IN THE MID/UPPER 90S AND A FEW
100 DEGREE READINGS NOT OUT OF THE QUESTION IN WRN MN. AT ANY
RATE...DID NOT SEE ANYTHING GLARING CHANGE WITH THE TEMP FORECAST
TODAY THAT REQUIRED ANY CHANGES IN THE GOING HEAT HEADLINES.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 359 PM CDT SUN AUG 25 2013
LONG TERM TRENDS CONTINUE TO SHOW HOT AND HUMID CONDITIONS WILL
CONTINUE THROUGH AT LEAST TUESDAY. LOCATION OF FRONTAL BOUNDARY
MONDAY NIGHT WILL DETERMINE TO WHAT EXTENT/LOCATION CONVECTIVE ACTIVITY
WILL DEVELOP OVER THE CWA. VARIOUS DETERMINISTIC MODELS SHOW THIS
BOUNDARY LIFTING SLOWLY BACK NORTH MONDAY NIGHT AND INTO TUESDAY
AS WEAK COOL FRONT/SURFACE LOW MOVES THROUGH THE AREA. WILL
CONTINUE THE CHANCE POPS OVER THE NORTHEAST THIRD OF THE AREA FOR
TUESDAY...WHICH SHOULD EXIT THE CWA BY TUESDAY EVENING. EXPECT
TEMPERATURES TO RANGE IN THE MID/SOME UPPER 90S AND DEWPOINTS
POOLING AHEAD OF BOUNDARY INTO THE LOWER 70S. HEAT INDEX VALUES
WILL RANGE 100F TO 105F WITH THE CURRENT HEAT ADVISORY/WARNING
STILL LOOKING GOOD CONTINUING THROUGH TUESDAY.
SOME COOLING BEHIND THE FRONT LINGERING INTO FRIDAY...MAINLY OVER
THE EASTERN PORTION OF THE CWA. RIDGING ALOFT DEVELOPS THEREAFTER
WITH SURFACE FRONT MEANDERING OVER CENTRAL MINNESOTA AGAIN INTO
THE WEEKEND. THE 12Z ECMWF IS SLOWER BUILDING THE UPPER RIDGE TO
THE EAST...WITH THE MAIN SURGE COMING NEXT SUNDAY. THE GFS BUILDS
IN NORTH BY SATURDAY. WILL GO ALONG WITH PRESENT TREND OF BRINGING
THE 90S BACK INTO THE AREA FOR SATURDAY AND SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1213 AM CDT MON AUG 26 2013
ALL THUNDERSTORM ACTIVITY HAS BEEN CONFINED TO NORTHEAST MN...LAKE
SUPERIOR...AND NOW THE U.P. OF MICHIGAN. THE ATMOSPHERE IS TOO
CAPPED FOR MUCH DEVELOPMENT THIS FAR SOUTH SO REMOVED TS MENTION
AT ALL TAF SITES. COULD STILL SEE ISOLATED CELLS DEVELOP
OVERNIGHT ACROSS ERN MN AND WRN WI...BUT THE PROBABILITY OF ANY
IN THE VICINITY OF TAF SITES IS QUITE LOW.
KMSP...VFR CONDITIONS EXPECTED. HIGH CLOUDS WILL STREAM
PERIODICALLY OVERHEAD THROUGH MONDAY.
/OUTLOOK FOR KMSP/
TUE...VFR. WIND SW 5-10 KT...BECOMING NW IN AFTERNOON.
WED...VFR. WIND LIGHT/VARIABLE.
THU...VFR. ISOLD SHRA/TS POSSIBLE. WIND LIGHT/VARIABLE.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ054>070-073>078-082>085-091>093.
HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ041>045-
047>053.
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ014>016-
023>028.
&&
$$
SYNOPSIS...MPG
SHORT TERM...MPG
LONG TERM...DWE
AVIATION...BORGHOFF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
129 AM EDT MON AUG 26 2013
.SYNOPSIS...
AN APPROACHING FRONTAL SYSTEM WILL BRING SCATTERED SHOWERS AND
THUNDERSTORMS LATE TONIGHT AND MONDAY. DRY WEATHER IS FORECAST FOR
TUESDAY...BUT MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
TUESDAY NIGHT AND WEDNESDAY AS ANOTHER COLD FRONT MOVES THROUGH
THE REGION. AFTER THIS FRONT PASSES BY...FAIR WEATHER IS EXPECTED
FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
11 PM UPDATE...
EARLIER FORECASTER CAPTURED THE TIMING OF AN AREA OF RAIN AND
THUNDER QUITE WELL THAT IS NOW CROSSING LAKE ONTARIO. MAIN
ADJUSTMENT WAS TO SHIFT AXIS A BIT FARTHER WEST BASED ON RADAR THAN
WHAT THE HRRR AND NAM 12 IS SHOWING NOW. IN ADDITION INCREASED
POPS TO CAT GIVEN RADAR TRENDS AND INCREASED CONFIDENCE OF A 2 TO
4 HOUR WINDOW OF STEADY RAIN OVERNIGHT. STILL NOT OVERLY CONFIDENT
ON HOW FAR SOUTH IT MAKES IT TOWARD NORTHERN PA BECAUSE WE ARE
QUITE DRY...BUT CNY...FINGER LAKES...AND SOUTHERN TIER SEEM A SAFE
BET FOR NOW. AS THIS MCS SHIFTS SOUTHEAST AND DIES DOWN EARLY
MONDAY MORNING...WE MAY SEE A BREAK LATER MONDAY MORNING INTO THE
EARLY AFTERNOON. ON THE EDGE OF TONIGHT`S CONVECTION HOWEVER A NEW
AREA IS EXPECTED TO DEVELOP AGAIN MONDAY AFTERNOON/EVENING. SIGNS
STILL POINT TO THE POTENTIAL FOR LOCALLY HEAVY RAIN IN THE
NORTHWEST MOIST FLOW. THE PREVIOUS AFD IS BELOW...
UPDATED THE NEAR TEAM TO BRING POPS IN ERLYR FROM THE MCS
THAT IS MOVING ACRS ONT AND QUE AND THE NERN GREAT LAKES. THE HRRR
HAS BEEN SHOWING THAT THIS PRECIP WILL GET INTO NC AND EC NY
BETWEEN 1Z AND 6Z WITH THE RAP NOW SPEEDING THE ARRIVAL UP TOO
OVER THE OTHER MODELS. SINCE THESE ARE RAPID UPDATE CYCLE MODELS
AND THE RADAR TRENDS ARE CLSR TO THESE MODELS I NOW BRING IN
PRECIP MUCH ERLYR IN LINE WITH KBUF/S RECENT UPDATE. OTHERWISE...NO
OTHER CHANGES THRU MONDAY.
PREVIOUS DSCN BELOW...
VISIBLE SATL IMAGERY SHOWS SCT CUMULUS FORMING WITH INSOLATION.
SOME CIRRUS FROM AN UPSTREAM MCS OVER NRN AND CNTRL ONTARIO AND
THE UPPER LAKES WILL STREAM SOUTHEASTWARD FOR THE REST OF THE
AFTERNOON....THUS SKIES WILL BE PS TO MS. CANADIAN RADAR LOOP
SHOWS AN MCS WITH SHOWERS AND THUNDERSTORMS TRACKING SEWRD ACRS
GEORGIAN BAY AND TWD SERN ONTARIO INTO WRN QUEBEC. CONVECTION
ALLOWING MESOSCALE MODELS ...WRF-NMM, WRF-ARW AND HRRR ALL SHOW
THE SRN EDGE OF THE PRECIPITATION SHIELD WITH THIS MCS SKIRTING
ACRS NRN AND ERN NY TONIGHT WITH ELEVATED INSTABILITY REMAINING ON
THE BACK EDGE OF THE MCS AS IT WORKS SEWRD. THE MAIN QUESTION IS
TIMING. LATEST WRF-NMM AND WRF-ARW BOTH HAVE SHRA AND TSRA
ARRIVING AFTER 6Z...MAINLY 9-12Z ACRS NC NY SEWRD TO THE
CATSKILLS. THE HRRR ON THE OTHER HAND HAS THE PRECIP SHIELD AND
SOME TSRA ARRIVING MUCH ERLYR...SPREADING FROM NC NY SOUTHWARD TO
THE CATSKILLS AND EVEN NE PA BETWEEN 1Z AND 6Z ABT 4-6 HOURS
SOONER. THE NAM...GFS AND CANADIAN ALL BRING SOME LIGHT PRECIP
INTO THESE AREAS LATE TONIGHT WITH THE RUC A LITTLE FASTER ON THE
ARRIVAL OF THE PRECIP. THUS THE HRRR AND THE RUC TO A LESSER
EXTENT ARE ON AN ISLAND BY THEMSELVES. HOWEVER...JUDGING BY
LATEST RADAR LOOP IT LOOKS LIKE THE HRRR HAS THE BEST HANDLE...BUT
THIS IS A MAJOR DEPARTURE FROM ERLYR FCSTS AND ALL OTHER MODEL
GUIDC AND SOUNDINGS INDICATE THAT IT IS VERY DRY BELOW 10000 FEET.
SO FOR NOW WILL HAVE CHC POPS NRN AND ERN CWA INCREASING AFTR
6Z...BUT WILL RE-EVALUATE AND MAY HAVE TO BUMP UP POPS ERLYR. I WUD
LIKE TO SEE RADAR TRENDS ON THE SRN EDGE OF THIS MCS AND IF THE
PRECIP IS REACHING THE GRND NEXT COUPLE HOURS.
FOR MONDAY...AN UPPER LEVEL WAVE WILL MOVE EASTWARD TWD NY AND PA
IN THE NW UPPER LEVEL FLO PATTERN. CONVECTION ALLOWING
MODELS...ESPECIALLY THE WRF-NMM, AND WRF-ARW AS WELL AS THE NAM
AND HIGHER RES CANADIAN ALL INDICATE SOME POTENTIAL FOR TRAINING
THUNDERSTORMS AS THE LL FLOW WILL BE W-NW AND FAIRLY ALIGNED WITH
THE UPPER LEVEL FLO. BOTH THE CANADIAN AND NAM HAVE A WELL
DEVELOPED JET ENTRANCE REGION CIRCULATION FOR OUR AREA WHEREAS THE
ERLYR EURO AND 12Z GFS REALLY DON/T. MODEL CAPES ARE AVERAGING
ARND 1000 J/KG OR SO WITH MODEST SHEAR VALUES...GENERALLY 25 TO 30
KNOTS IN THE LOWEST 6 KM WITH MOST OF THE SHEAR ACTUALLY BETWEEN 0
AND 3 KM. I CAN EASILY SEE AN MCS EVOLVING OVER OUR REGION MON PM
AND...IN ITS WAKE SOME TRAINING STORMS WITH LOCALLY HEAVY RAINS.
FOR NOW...THINK LIKELY POPS ARE ON ORDER MON PM. THERE IS WAY TOO
MUCH UNCERTAINTY AS TO HEAVY RAINFALL POTENTIAL. NAM AND CMC GIVE
THE REGION A STRIPE OF 1-2 INCHES OF RAIN WHICH SHUDN/T BE MUCH OF
A PROBLEM AT ALL. HOWEVER WILL ALERT FUTURE SHIFTS FOR POTENTIAL
TO RAISE SITUATIONAL AWARENESS. AS FOR SEVERE POTENTIAL...THERE CUD BE
SOME LOCALLY DAMAGING WINDS...BUT AT THIS POINT IT LOOKS LIKE THE
CAPE AND SHEAR FALL SHORT OF WHAT WE WOULD EXPECT FOR AN OUTBREAK.
SPC CONCURS IN THEIR DAY 2 OUTLOOK.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
I KEPT TUESDAY DRY AS NY AND PA IS IN BETWEEN SYSTEMS WITH A SMALL
BUBBLE HIGH OVHD. ALL SYNOPTIC MODELS INDICATE THAT THE MAJORITY
OF THE DAY IS DRY WITH JUST A FEW HUNDREDTHS POSSIBLE IN THE SW
AND FAR NE PART OF OUR CWA.
FOR WEDNESDAY...MODELS ARE IN AGREEMENT THAT ANOTHER MCS AND SHRT
WAVE WILL AFFECT THE REGION. MODEL TIMING AND PLACEMENT IS
UNCERTAIN THIS FAR OUT. SO I HAVE GENERIC CHC POPS FOR SHRA AND
TSRA TO COVER IN LINE WITH NEIGHBORING OFFICES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
NO MAJOR CHANGES TO THIS PART OF THE FORECAST. THE BROAD...AND
HOT LATE SEASON RIDGE OVER MUCH OF THE WESTERN AND CNTRL CONUS IS
STILL EXPECTED TO EXPAND INTO THE NORTHEAST BY THE END OF THE
PERIOD WITH REGIONAL HIGH TEMPERATURES EXPECTED TO RISE WELL INTO
THE MID 80S OVER NEXT WEEKEND.
THE ADVERTISED FRONTAL SYSTEM...POSSIBLY ACCOMPANIED BY A COMPLEX
SECONDARY LOW DEVELOPMENT ON THE BOUNDARY...IS STILL FORECAST TO
BE MOVING EAST OF THE AREA IN THE WEDNESDAY NIGHT-THURSDAY TIME
FRAME. THE FORECAST WILL STILL FEATURE DECREASING POPS WITH TIME
INTO THURSDAY...THEN WITH THE BROAD RIDGE IN PLACE THURSDAY NIGHT
AND NEXT WEEKEND LOOKS RAIN FREE AND WARMER AT THIS TIME.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
06Z MON UPDATE... VFR SHOULD PREVAIL INTO THIS AFTN...WITH JUST
SOME UNRESTRICTED -SHRA/SPRINKLES ACRS THE RGN...SPCLY EARLY THIS
MRNG (THROUGH 12-15Z).
THIS AFTN INTO THE EARLY EVE PD...MORE ORGANIZED SHWRS/TSTMS ARE
EXPECTED...PARTICULARLY ACRS NY`S SRN TIER AND NE PA (IMPACTING
MOSTLY KELM/KITH/KBGM/KAVP). THUS...WE`LL CARRY TEMPO GROUPS FOR
MVFR RESTRICTIONS AND TSRA AT THESE FOUR SITES...WITH A PROB30
GROUP FOR NOW AT KSYR/KRME.
LTR THIS EVE/OVERNIGHT...AS A BNDRY COMES THROUGH FROM THE
NW...PCPN SHOULD COME TO AN END. HOWEVER...SOME LWR CIGS ARE
FORESEEN...SO MVFR RESTRICTIONS WERE CARRIED AT ALL SITES EXCEPT
KAVP...STARTING IN THE 03-05Z TIME FRAME.
SFC WINDS MAINLY AOB 5 KT EARLY THIS MRNG...WILL INCREASE OUT OF
THE SW TO 5-10 KT BY 12-15Z...WITH W TO NW WINDS INCREASING
FURTHER...AND BCMG GUSTY THIS AFTN. WINDS WILL SHIFT INTO THE N
AND NE BY LATER THIS EVE (BY 00-03Z).
OUTLOOK...
TUE...MAINLY VFR.
WED...AT LEAST BRIEF RESTRICTIONS PSBL...IN SHRA/TSRA.
THU AND FRI...MAINLY VFR ONCE AGN.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN/HEDEN
SHORT TERM...DJN
LONG TERM...JAB
AVIATION...MLJ/MSE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1224 AM CDT MON AUG 26 2013
.UPDATE...
ISSUED AT 1224 AM CDT MON AUG 26 2013
LATEST LOCAL/REGIONAL RADAR SHOWS SHOWERS DWINDLING OVER OUR FAR
SOUTHEAST ZONES AND WILL CONTINUE TO SHOW THAT TREND FROM PREVIOUS
FORECAST. UPSTREAM RADAR PER RAPID CITY AND BOWMAN ND SHOW THE
BEGINNING SIGNS OF ANOTHER ROUND OF SHOWERS AND EVENTUALLY SOME
THUNDERSTORMS THAT ARE DEVELOPING AND MOVING NORTHEAST WITH TIME.
THE HIGH RESOLUTION HRRR...4KM NAM...00Z NAM12 AND TO AN EXTENT
THE 00Z GFS ALL SHOW MULTIPLE SHORTWAVES TO SLIDE OVER THE LEE
SIDE TROUGH IN SOUTHEAST MONTANA OVERNIGHT PRODUCING AN AREA OF
SHOWERS AND THUNDERSTORMS AS MENTIONED ABOVE...MOVING INTO OUR
SOUTHWEST ZONES BETWEEN 09Z AND 12Z MONDAY. THIS AREA EXPANDS
NORTHEAST INTO WESTERN AND CENTRAL NORTH DAKOTA WHICH THE CURRENT
FORECAST GRIDS SHOW. IT APPEARS THAT THE DAYLIGHT HOURS MONDAY
WILL BE THE PRIME TIME FOR PRECIPITATION...THEN DECREASING FROM
WEST TO EAST BY MID TO LATE AFTERNOON. MINIMAL UPDATES NEEDED
OTHER THAN ADDING SOME MENTION OF PRECIPITATION INTO THE SOUTHWEST
TOWARD 12Z MONDAY.
UPDATE ISSUED AT 1000 PM CDT SUN AUG 25 2013
GIVEN THE LATEST RADAR TRENDS AND INCOMING 00 UTC
GUIDANCE...REDUCE POPS TO JUST THE FAR SOUTH CENTRAL AND SOUTHERN
JAMES RIVER VALLEY FOR THE REMAINDER OF THE NIGHT. OTHERWISE...THE
REST OF THE FORECAST IS ON TRACK...WITH A MILD OVERNIGHT EXPECTED
WITH LOWS IN THE MID TO UPPER 60S FOR MOST LOCATIONS.
UPDATE ISSUED AT 752 PM CDT SUN AUG 25 2013
AS OF 0045 UTC...THUNDERSTORMS REMAIN FOCUSED FROM LEMMON TO
TIMBER LAKE SOUTH DAKOTA WHERE LOW LEVEL CONVERGENCE IS MAXIMIZED.
AGAIN...THE HRRR HAS HAD A GOOD HANDLE ON THE CONVECTION THIS
EVENING AND WILL FOLLOW ITS LATEST 23 UTC RUN FOR POPS...WHICH
GENERALLY REMAIN ALONG AND SOUTH OF I-94 WITH THE ONSET OF A MODEST
LOW LEVEL JET. THE OVERALL SEVERE THREAT IS MARGINAL ACROSS FAR
SOUTHERN NORTH DAKOTA AS THE BOUNDARY LAYER BEGINS TO STABILIZE.
HOWEVER...WILL HAVE TO MONITOR FOR STRONG WINDS GIVEN DOWNDRAFT
CAPE VALUES NEAR 1200 J/KG.
UPDATE ISSUED AT 520 PM CDT SUN AUG 25 2013
QUICK UPDATE TO INCREASE AND EXPAND POPS ACROSS WESTERN AND
CENTRAL NORTH DAKOTA FOR THE REMAINDER OF THE EVENING AND
OVERNIGHT. SURFACE BASED CONVECTION HAS BEEN INCREASING ACROSS
SOUTHWEST NORTH DAKOTA AND NORTHWEST SOUTH DAKOTA SINCE 2130 UTC
GIVEN THE LOSS OF CAPPING AND INCREASING UPPER LEVEL FORCING WITH
THE SHORTWAVE ENTERING WESTERN NORTH DAKOTA EVIDENT ON THE LATEST
WATER VAPOR IMAGERY. DEEP LAYER SHEAR ON THE ORDER OF 30-35 KTS
SUPPORTS THE POTENTIAL FOR PERHAPS A SUPERCELL OR TWO...WITH ML
CAPE VALUES AROUND 1500 J/KG. WHILE HIGH FREEZING LEVELS LIMIT THE
HAIL THREAT...DOWNDRAFT CAPE VALUES NEAR 1400 J/KG SUGGEST A
DAMAGING WIND THREAT WITH THE STRONGER STORMS. THE 18 UTC NAM AND
20 UTC HRRR ARE HANDLING THE CONVECTION WELL...WITH THE HRRR
SUGGESTING THE CONVECTION WILL PROPAGATE INTO BISMARCK AND MANDAN
LATER TONIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 317 PM CDT SUN AUG 25 2013
LATE SUNDAY AFTERNOON...SURFACE HIGH PRESSURE WAS ACROSS SOUTHERN
MANITOBA. A WEAK COLD FRONT WAS SLIDING SOUTH ACROSS CENTRAL NORTH
DAKOTA. ON SATELLITE...WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH
MOVE THROUGH WYOMING INTO CENTRAL MONTANA. THIS FEATURE IS
SUPPORTING CONVECTION ACROSS EASTERN MONTANA. SOME SHOWERS AND
ISOLATED THUNDERSTORMS SHOULD ENTER WEST CENTRAL AND NORTHWEST NORTH
DAKOTA LATE THIS AFTERNOON AND EVENING. THEN PROGRESSIVELY TRACKED
THE SLIGHT CHANCE TO CHANCE OF THUNDERSTORMS INTO WESTERN NORTH
DAKOTA OVERNIGHT AND INTO CENTRAL NORTH DAKOTA MONDAY. WITH THE
BASIC RIDGE PATTERN IN PLACE OVER THE CENTRAL AND NORTHERN
PLAINS...CONTINUED WARM TEMPERATURES EXPECTED ON MONDAY...HOWEVER
WITH COLD FRONT BRINGING A SLIGHT RELIEF WITH HIGHS IN THE UPPER 80S
NORTH TO LOWER 90S SOUTH ON MONDAY.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 317 PM CDT SUN AUG 25 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND
DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A
STRONG RIDGE OVER THE CENTRAL U.S. THAT RETROGRADES FROM THE
MISSOURI VALLEY WEST INTO THE SOUTHERN PLAINS THROUGH THE PERIOD.
NORTH DAKOTA WILL REMAIN NEAR THE APEX OF THE RIDGE THROUGH THE LONG
TERM FORECAST PERIOD...WHICH WILL CONTINUE TO INDICATE ABOVE AVERAGE
DAYTIME HIGH TEMPERATURES. SOUTHERN PORTIONS OF THE CWA COULD FLIRT
WITH HEAT ADVISORY CRITERIA LATER IN THE WEEK. IN ADDITION...ALMOST
DAILY THUNDERSTORM CHANCES CAN BE EXPECTED WITH HIGH CAPES EVERY DAY
BUT A STRONG CAP LIMITING CONVECTION.
THE DETERMINISTIC MODELS CONTINUE TO ADVERTISE A FEW...MORE
SIGNIFICANT...WAVES WORKING THROUGH THE MEAN RIDGE AND BRINGING
BETTER PRECIPITATION CHANCES. ON MONDAY AND INTO MONDAY NIGHT THE
ECMWF/GEM APPEAR STRONGER WITH A WAVE MOVING INTO NORTH DAKOTA AND
BRING QPF ACROSS THE NORTH. THE SOUTH MAY REMAIN CAPPED UNDER WARM
MID LEVEL TEMPERATURES.
WAVES CONTINUE TO WORK THROUGH THE MEAN RIDGE ON WEDNESDAY THROUGH
SATURDAY BUT TIMING AND PLACEMENT DIFFERENCES CONTINUE BETWEEN
MODELS AND MODEL RUNS. THEREFORE WILL CONTINUE TO UTILIZE A BLENDED
SOLUTION FOR PRECIPITATION. THIS WILL MEAN BETTER CHANCES WEDNESDAY
THROUGH THURSDAY AFTERNOON...THEN CHANCES ARE ON AND OFF FRIDAY
NIGHT THROUGH SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1224 AM CDT MON AUG 26 2013
SCT TO BKN MID LEVEL CLOUDS ALONG WITH A CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL CONTINUE THIS TAF PERIOD. EXPECTING SOME
SHOWERS/THUNDERSTORMS TO AFFECT KDIK BY 12Z MONDAY...WITH A
VCTS AT KISN. THE AREA OF SHOWERS AND THUNDERSTORMS SHOULD DEVELOP
FURTHER AND REACH KMOT/KBIS BETWEEN 15Z AND 18Z MONDAY. WILL
MONITOR AND SEE HOW THE AREA OF PRECIPITATION DEVELOPS TONIGHT AND
MAKE FURTHER ADJUSTMENTS ON TIMING FOR THE 12Z TAF FORECAST. FOR
NOW HAVE INDICATED AND MAINTAINED THE VCSH/VCTS AT ALL AERODROMES
EXCEPT KDIK WHERE CONFIDENCE IS A BIT HIGHER NOW THAT AN AREA OF
SHOWERS AND THUNDERSTORMS WILL REACH THEM BY 12Z MONDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...WAA
LONG TERM...JV
AVIATION...KS
AREA FORECAST DISCUSSION
NWS MEDFORD OR
1040 PM PDT SUN AUG 25 2013
.DISCUSSION...NEW EVENING UPDATE. THE LATEST RAP MODEL IS SHOWING
THE CONVECTION TO CONTINUE UP THE SPINE OF THE CASCADES THROUGH 12Z.
ALTHOUGH IT HAS WHAT SEEMS TO BE UNREALISTICALLY HIGH QPF
AMOUNTS...IT IS INDEED HAPPENING AT THIS TIME AND OTHER MODELS ARE
NOT PICKING UP ON THIS. HAVE UPDATED TO ADD SLIGHT CHANCE POPS IN
THAT AREA WITH AN OCCASIONAL BOLT OF LIGHTNING POSSIBLE...AS WELL AS
ADDING FOG TO THE FULL COAST THAT IS ALREADY THERE.
PREVIOUS DISCUSSION...THE LATEST WATER VAPOR IMAGE SHOWS THE UPPER
TROUGH OVER SOUTHWEST OREGON AND WILL CONTINUE TO MOVE NORTHEAST.
THUNDERSTORMS AHEAD OF THE TROUGH ARE MAINLY CENTERED OVER THE
NORTHERN CASCADES...KLAMATH COUNTY AND NORTHEAST LAKE COUNTIES AND
ARE MOVING NORTH TO NORTHEAST. COULD NOT RULE OUT THE POTENTIAL FOR
A FEW STORMS TO REACH SEVERE LEVEL FOR THE NEXT 4-6 HOURS...BUT THIS
WILL BE EXCEPTION NOT THE NORM.
ISOLATED THUNDERSTORMS ARE STARTING TO POP UP IN CENTRAL MODOC
COUNTY. MEANWHILE WERE STARTING TO SEE SOME CLEARING WITH MORE
CUMULUS DEVELOPMENT OVER SOUTHWEST OREGON AND SISKIYOU COUNTY WITH A
FEW CELLS STARTING TO DEVELOP. LATEST MESOSCALE ANALYSIS SHOWS LOW
CINS AND HIGHER SURFACE CAPE VALUES NOSING INTO WESTERN SISKIYOU
COUNTY. HOWEVER 700-500 MB LAPSE RATES ARE NOT AS STEEP WHICH WAS
PROBABLY A RESULT IN LATENT HEAT RELEASE FROM THIS MORNINGS
PRECIPITATION. THIS COULD BE THE LIMITING FACTOR FOR ADDITIONAL
STORM DEVELOPMENT UNLESS THE CAP BREAKS.
THE ABOVE MENTIONED UPPER TROUGH MOVES NORTH THIS EVENING AND
ACTIVITY SHOULD BEGIN TO DECREASE FROM SOUTH TO NORTH AS THE
ATMOSPHERE BECOMES STABLE. MOST IF NOT ALL PRECIPITATION WILL
SHIFT NORTH OF THE FORECAST AREA AROUND MIDNIGHT.
THE LONGWAVE TROUGH FOR MOST OF NEXT WEEK SHOULD REMAIN OFFSHORE
WITH A SOUTHWEST FLOW ALOFT. SEVERAL WEAK FRONTS WILL BRUSH BY
OVER THE NORTHWEST PART OF THE FORECAST AREA KEEPING AT LEAST A
SLIGHT CHANCE OF RAIN. THE FIRST IS EXPECTED TO MOVE THROUGH MONDAY
NIGHT, THE NEXT ONE WEDNESDAY NIGHT/THURSDAY. ELSEWHERE IT SHOULD BE
DRY WITH NEAR NORMAL TEMPERATURES.
EC AND GFS STILL DIFFER NEXT WEEKEND, BUT NOT AS MUCH AS YESTERDAY.
THE POSITION AND TIMING OF DEEPENING TROUGH AND UPPER LOW ARE
DIFFERENT AND THE EC STILL SHOWING THE UPPER LOW PROGRESSING THROUGH
THE PAC NW. MEANWHILE THE GFS DROPS THE UPPER LOW SOUTH ALONG THE
OREGON COAST THEN MOVING INLAND SUNDAY. DID ADJUST POPS HIGHER
SUNDAY WITH BOTH MODELS SHOWING SOME QPF AND MADE LITTLE CHANGES IN
THE EXTENDED. -PETRUCELLI
&&
.AVIATION...ISOLATED SHOWERS AND THUNDERSTORMS WILL LINGER LATE THIS
EVENING (UNTIL AROUND 06Z) FROM THE CASCADES EASTWARD. THE AIR MASS
WILL STABILIZE OVERNIGHT. MARINE STRATUS HAS ALREADY DEVELOPED AT
THE COAST. LIFR CEILINGS AND VISIBILITIES WILL CONTINUE AT THE COAST
OVERNIGHT INTO MID-MORNING (UNTIL AROUND 18Z). ALSO, MVFR CEILINGS
ARE EXPECTED TO SPREAD INTO THE UMPQUA BASIN AFTER MIDNIGHT AND ALSO
LINGER UNTIL AROUND 18Z. PATCHY GROUND FOG IS POSSIBLE NEAR KLMT
AROUND SUNRISE (BETWEEN 12Z AND 16Z).
OTHERWISE...CONDITIONS ARE EXPECTED TO REMAIN VFR OVER THE NEXT 24
HOURS WITH DECREASING CLOUDS LATE TONIGHT INTO MONDAY. WEAK
INSTABILITY IS EXPECTED MONDAY AFTERNOON IN THE VICINITY OF CRATER
LAKE WITH A SLIGHT CHANCE OF THUNDERSTORMS.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 9 AM TO
5 PM PDT MONDAY FOR PZZ370-376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 9 AM TO 8 PM PDT
MONDAY FOR PZZ370-376.
$$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
339 AM CDT MON AUG 26 2013
.TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
COLD POOL FINALLY STARTING TO TAKE CONVECTIVE COMPLEX ACROSS NRN
WI TO THE SOUTH SOUTHEAST. WILL HAVE TO SEE HOW IT SURVIVES AS IT
RUNS INTO 700MB THERMAL RIDGE OVER CENTRAL WI...THOUGH WEAK SHORT
WAVE MOVING ACROSS REGION HAS COOLED 700MB TEMPS TO BETWEEN 10C
AND 11C OVER E CENTRAL AND S CENTRAL WI. CURRENT TRACK WOULD BRING
COMPLEX INTO FAR NRN CWA AROUND 830 AM. HRRR AND HI-RES ARW MODELS
TAKE BULK OF COMPLEX TO THE EAST. WILL FOLLOW CURRENT CONSENSUS
THAT TAKES THIS MORE EASTERLY TRACK...BUT WILL MONITOR CLOSELY.
SOME SIGNAL IN MODEL QPF THAT RESIDUAL OUTFLOW BOUNDARY COULD BE
FOCUS FOR AFTERNOON/EVENING CONVECTION AS NEXT SHORT WAVE TOPS
RIDGE AND CROSSES NRN WI/UP OF MI TONIGHT. SPC STORM SCALE
ENSEMBLE OF OPPORTUNITY/SSEO SHOWS BETTER PROBABILITY FOR UPDRAFT
HELICITY EXCEEDING 25M2/S2..A GOOD INDICATOR FOR ROTATING/SEVERE
STORMS...AND REFLECTIVITIES GREATER THAN 40 DBZ REMAIN ACROSS NRN
WI THOUGH A 10 TO 20 PCT HELICITY PROB AND 50 TO 60 PCT
REFLECTIVITY PROB DO DIP INTO THE FAR NRN CWA AFTER 06Z IN LINE
WITH SOUTHERN EDGE OF CURRENT DAY ONE OUTLOOK. WITH CAP
STRENGTHENING FROM NORTH TO SOUTH THROUGH CWA WILL LIMIT MAINLY
SLIGHT CHANCE/CHANCE POPS TO THE NORTHEAST THIRD.
925MB TEMPERATURES SUPPORT HIGHS A FEW DEGREES WARMER THAN
YESTERDAY...WITH UPPER 80S IN THE FAR EAST AND LOW TO MID 90S IN
THE WEST. A FEW SPOTS IN THE FAR WEST WILL REACH HEAT INDEX VALUES
OF 100F...BUT AREAL EXTENT TOO SMALL TO ISSUE A HEADLINE. WILL
CONTINUE HIGHLIGHTING IN SPS/HWO/TOP NEWS FOR NOW. A WARM MUGGY
NIGHT TONIGHT WITH LOWS ONLY COOLING TO THE 70S.
.TUESDAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM.
SHORT TERM MODELS SHOW THE 500MB HIGH REMAINING ACROSS SOUTHWEST
MISSOURI DURING THIS PERIOD...KEEPING NORTHWESTERLY FLOW AT THIS
LEVEL ACROSS THE WESTERN GREAT LAKES REGION. SHEARED VORTICITY
MAXIMA SHIFT THROUGH THE AREA TUESDAY AFTERNOON INTO WEDNESDAY.
A WEAK SURFACE LOW MOVING FROM CENTRAL MINNESOTA AT 12Z TUESDAY
SOUTHEAST INTO OR CLOSE TO SOUTHERN WISCONSIN BY 00Z WEDNESDAY. IT
THEN WASHES OUT TUESDAY NIGHT. QUASISTATIONARY FRONTAL BOUNDARY
EXTENDS EAST FROM THE WEAK LOW ACROSS CENTRAL WISCONSIN
TUESDAY...BEFORE SLIDING SOUTHWARD ACROSS THE AREA LATER TUESDAY
AND TUESDAY NIGHT AS A COLD FRONT.
LOW LEVEL JET NOSE/FOCUSED WARM AIR ADVECTION WILL SUPPORT AN MCS
SHIFTING EAST SOUTHEAST ACROSS NORTHERN AND CENTRAL WISCONSIN
TUESDAY MORNING...POSSIBLY CLIPPING THE NORTHERN AND NORTHEASTERN
PORTIONS OF THE FORECAST AREA. MEAN LAYER CAPES INCREASE DURING
THE MORNING ABOVE CAP...WITH ENOUGH DEEP LAYER SHEAR TO BRING AN
OUTSIDE CHANCE FOR A SEVERE STORM OR TWO. HIGH PRECIPITABLE WATER
VALUES TO AROUND 2 INCHES SUGGEST LOCALLY HEAVY RAINFALL WOULD
ALSO BE POSSIBLE WITH ANY CONVECTION. CONTINUED CHANCE POPS FOR
NOW IN THE NORTH AND NORTHEAST COUNTIES...GIVEN SOME UNCERTAINTY
WITH THE TRACK OF THE MCS.
NAM MORE AGGRESSIVE WITH LOW LEVEL FRONTOGENESIS RESPONSE WITH
FRONT SLIDING SOUTH THROUGH THE AREA LATER TUESDAY AND TUESDAY
NIGHT THAN THE GFS. STILL...ENOUGH UPWARD MOTION WITH FRONT TO
COMBINE WITH MEAN LAYER CAPE AND DEEP LAYER SHEAR TO BRING
POSSIBILITY OF MULTICELL STORMS WITH SEVERE POTENTIAL LATER
TUESDAY INTO TUESDAY EVENING. BEST SHOT IN THE NORTH AND EAST
WHERE SPC DAY 2 SLIGHT RISK IS LOCATED. LOCALLY HEAVY RAINFALL
REMAINS POSSIBLE WITH HIGH PRECIPITABLE WATER VALUES. BOTH NAM AND
GFS BRING SOME QPF THROUGH THE AREA...MAINLY IN THE EAST BY
EVENING. KEPT CHANCE POPS GOING DURING THE AFTERNOON...MAINLY IN
THE NORTH AND EAST.
MEAN LAYER CAPES FALL OFF QUICKLY DURING THE EVENING AS THE FRONT
PASSES THROUGH. CONTINUED CHANCE POPS IN THE EVENING...THEN DROP
OFF AFTER MIDNIGHT. MOISTURE LINGERING BEHIND THE FRONT WITH
COOLER AIR MOVING IN SHOULD GENERATE PATCHY FOG ACROSS THE AREA
LATER TUESDAY NIGHT.
SOUTHWEST WINDS WILL LINGER TUESDAY ACROSS THE AREA...AND SHOULD
COMBINE WITH 925MB TEMPERATURES IN THE UPPER 20S CELSIUS RANGE TO
BRING LOWER TO MID 90S TO MOST OF THE AREA...HIGHEST IN SOUTH
CENTRAL WISCONSIN.
BIG QUESTION IS IF CIRRUS FROM POSSIBLE CONVECTION TO THE NORTH
AND NORTHEAST MOVES OFF BY THE AFTERNOON. IF IT DOES...SHOULD SEE
THE LOWER TO MID 90S OCCUR. HEAT INDEX VALUES WILL BE IN THE 97 TO
102 RANGE IN MOST OF SOUTH CENTRAL AND SOUTHEAST WISCONSIN...SO A
HEAT ADVISORY FOR TUESDAY AFTERNOON AND EARLY EVENING WOULD BE
NECESSARY. IF THE CLOUDS HANG AROUND INTO THE AFTERNOON...THEY
WILL HOLD DOWN TEMPERATURES ENOUGH TO PREVENT HEAT INDEX VALUES
FROM REACHING 100 DEGREES. THUS...WILL HOLD OFF ON ANY HEAT
HEADLINES UNTIL BETTER HANDLE ON POSSIBLE CONVECTION AND CLOUDS
IS GAINED.
SLIGHTLY COOLER AIRMASS WORKS SOUTHWARD INTO THE AREA FOR
WEDNESDAY AND WEDNESDAY NIGHT...AS HIGH PRESSURE WORKS INTO THE
REGION. LOWER 80S NEAR THE LAKE WITH MID TO UPPER 80S INLAND ARE
EXPECTED WEDNESDAY. NAM HAS ODD LOOKING QPF IN THE AREA WEDNESDAY
WITH SOME LINGERING MEAN LAYER CAPE. THE GFS IS DRY AND SEEMS MORE
REASONABLE. THUS...QUIET WEATHER IS EXPECTED WEDNESDAY AND
WEDNESDAY NIGHT.
.THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM.
GFS AND ECMWF SHOWING SOMEWHAT SIMILAR TRENDS DURING THIS PERIOD.
THEY TAKE HIGH PRESSURE EAST OF THE AREA THURSDAY...WITH WEAK LOW
PRESSURE REMAINING IN EASTERN SOUTH DAKOTA THURSDAY NIGHT INTO
FRIDAY. BOTH MODELS SHOW QPF MOVING SOUTHEAST INTO THE AREA
THURSDAY NIGHT AND LINGERING INTO FRIDAY...RIDING THE
QUASISTATIONARY SURFACE BOUNDARY AND LOW LEVEL THERMAL RIDGE. THIS
BOUNDARY THEN REMAINS IN THE SAME AREA INTO SATURDAY
EVENING...WITH MORE QPF IN OR NEAR THE AREA.
WARM AIR ADVECTION PUSH SUNDAY PER GFS BRINGS HOT AND HUMID
CONDITIONS BACK TO THE AREA WITH SOUTHWEST WINDS. ECMWF BRINGS
COLD FRONT THROUGH THE AREA SUNDAY AND COOLS THINGS DOWN SOMEWHAT.
MOST IF NOT ALL OF THE QPF ASSOCIATED WITH WARM FRONT REMAINS
NORTH OF THE AREA SUNDAY PER GFS. FOR NOW...USED CONSENSUS POPS
AND TEMPERATURES FOR THE THURSDAY THROUGH SUNDAY PERIOD...WITH 90S
ACROSS MOST OF THE AREA BY SUNDAY.
&&
.AVIATION/12Z TAFS/...WILL CONTINUE VFR CONDITIONS AT THE TAF
SITES WITH AN EYE TOWARD NRN WI COMPLEX THAT IS FINALLY TAKING THE
EXPECTED TURN TO THE SOUTH SOUTHEAST. PUT IN A SLIGHT CHANCE FOR
THUNDERSTORMS ALONG AND NORTHEAST OF AN OXFORD TO MEQUON LINE THIS
AFTERNOON FOR POSSIBLE DEVELOPMENT ALONG OUTFLOW FROM THIS COMPLEX
THAT IS EXPECTED TO PASS TO THE EAST INTO LOWER MI.
WILL KEEP CLOSE WATCH FOR POTENTIAL OF STORMS TO REACH UES AND MKE
AROUND 16Z IF THE COMPLEX TAKES MORE OF A SOUTHERLY TRACK. ANOTHER
CHANCE AT THUNDERSTORMS TONIGHT INTO TUESDAY BUT AGAIN MAJORITY OF
MODEL GUIDANCE KEEPS CONVECTION NORTH OF TAF SITES...THOUGH UES
AND MKE WOULD AGAIN HAVE THE BETTER CHANCE TO SEE STORMS IF THEY
MAKE IT FARTHER SOUTH THAN EXPECTED.
&&
.MARINE...WIND GUSTS WILL APPROACH SMALL CRAFT ADVISORY LEVELS IN
NORTHERN ZONES TODAY...BUT NOT FREQUENT ENOUGH FOR A HEADLINE.
THUNDERSTORM CHANCES LOOK TO BE BETTER FROM MILWAUKEE NORTH...LATE
THIS MORNING INTO EARLY AFTERNOON...AND AGAIN LATE TONIGHT INTO
TUESDAY MORNING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
326 AM CDT MON AUG 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 309 AM CDT MON AUG 26 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER
THE PACIFIC NORTHWEST AND EASTERN PACIFIC...AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUES TO STREAM OUT OF BAJA CALIFORNIA...UP THROUGH THE DAKOTAS
AND INTO THE NORTHERN GREAT LAKES AROUND THE SUBTROPICAL RIDGE. ONE
SUCH SHORTWAVE COMBINED WITH 700MB MOISTURE TRANSPORT SUPPORTING
CONVECTION TRACKING ACROSS FAR NORTHERN WI AND UPPER MICHIGAN.
REGARDING MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED
VALUES OF 1.5-2 INCHES FROM EASTERN SOUTH DAKOTA INTO THE NORTHERN
GREAT LAKES. AIRMASS IS ALSO VERY WARM WITH 850MB TEMPS FROM 00Z
RAOBS OF 22-24C ACROSS THE FORECAST AREA AND 24-28C OVER THE
NORTHERN PLAINS. WITH THE FORECAST AREA IN THE WARM SECTOR...SOUTH
OF A WARM FRONT POSITIONED OVER FAR NORTHERN WI...A SOUTHERLY BREEZE
HAS ONLY ALLOWED TEMPS TO FALL INTO THE MID TO UPPER 70S. THIS SAME
SOUTHERLY BREEZE HAS ADVECTED IN SOME LOWER DEWPOINTS...WHICH HAVE
FALLEN INTO THE 60S...LOWEST IN THE SOUTHEAST HALF OF THE AREA. 00Z
DVN SOUNDING REALLY SHOWED THE DRIER AIR COMPARED TO MPX.
..MODEL VERIFICATION..
HAVE INCLUDED THIS SECTION AS IT HAS HIGH IMPORTANCE WITH THE
FORECAST OF HIGH TEMPERATURES AND CONVECTION. LOOKING AT 00Z RAOBS
FOR 925MB TEMPS AND COMPARING TO 25.00Z MODEL GUIDANCE...THE ECMWF
WAS THE BEST WITH ALMOST NO ERROR ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST. THE GFS WAS GENERALLY 1-2C TOO HIGH. LASTLY...THE
NAM/RAP WERE THE WORST...HAVING ERRORS ON THE ORDER OF 3-6C...
HIGHEST AT MSP. BECAUSE THE NAM/RAP WERE TOO HIGH...IT BROKE THE CAP
AND BROUGHT THE CONVECTION WAY TOO FAR SOUTH.
..HAZARDS..
1. HEAT. TEMPERATURES ARE LIKELY TO BE A FEW DEGREES HIGHER TODAY
AND WITH DEWPOINTS CLIMBING BACK INTO THE LOW 70S...HEAT INDICES
SHOULD TOP OUT IN THE 100-105 RANGE. THE HIGHEST HEAT INDICES LOOK
TO OCCUR FROM LAKE CITY DOWN TO LA CROSSE...AND HAVE UPGRADED THIS
AREA TO AN EXCESSIVE HEAT WARNING.
2. STORMS. SOME SEVERE POTENTIAL AFTER MIDNIGHT TONIGHT...MAINLY
ACROSS TAYLOR/CLARK COUNTIES. HAVE TO WATCH RAINFALL AMOUNTS TOO.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE SUGGESTS THE SUBTROPICAL RIDGING RETROGRADES
JUST SLIGHTLY WESTWARD DURING THE NEXT 24 HOURS. THE MAIN FEATURE OF
FOCUS IS A STRETCHED OUT SHORTWAVE IN THE MONSOONAL FLOW...LOCATED
FROM EASTERN UTAH INTO SOUTH CENTRAL WYOMING. MODELS BRING THIS
SHORTWAVE INTO THE DAKOTAS BY 00Z AND PERHAPS AS FAR EAST AS WESTERN
UPPER MI BY 12Z. THIS SHORTWAVE HELPS TO LIFT A SURFACE LOW SITTING
NEAR THE BLACK HILLS OF SOUTH DAKOTA TO NEAR MINNEAPOLIS BY 12Z TUE.
..DETAILS..
FOCUS FOR POTENTIAL CONVECTION TODAY WILL LIE ON THE LOCATION OF THE
WARM FRONT IN NORTHERN WI. FIRST OFF...THE CURRENT CONVECTION
CROSSING FAR NORTHERN WI AND UPPER MI COULD DROP INTO TAYLOR AND
POSSIBLY CLARK COUNTY BEFORE WEAKENING THIS MORNING. THE OUTFLOW
FROM THE CONVECTION SHOULD HELP PUSH THE FRONT SOUTH TOWARDS I-94
THIS AFTERNOON. THEN...THE NEXT QUESTION IS IF THE AIRMASS IS
CAPPED...WHICH ENTIRELY DEPENDS ON HOW WARM WE GET. THERE SHOULD BE
PLENTY OF SUN TODAY ACROSS THE FORECAST AREA WITH MAYBE A FEW STRAY
CIRRUS CLOUDS. ECMWF 925MB TEMPS ARE PROGGED ABOUT 1-2C HIGHER
COMPARED TO YESTERDAY...THUS ANTICIPATING HIGHS TO BE ABOUT 1-3F
HIGHER... YIELDING READINGS MAINLY IN THE LOW TO MID 90S. A FEW
SPOTS LIKE LSE COULD EVEN HIT THE UPPER 90S. ECMWF ALSO DID VERY
WELL WITH THE DEWPOINTS YESTERDAY AND SUGGESTS THEY SHOULD CLIMB
INTO THE LOW 70S IN THE AFTERNOON...DUE TO EVAPOTRANSPORATION AND
THE HIGHER MOISTURE TO OUR NORTHWEST SLIDING SOUTH. THE FORECAST
HIGHS AND DEWPOINTS WOULD SEEM TO POINT TO POTENTIAL FOR THE CAP TO
BREAK...THUS HAVE INCLUDED 20-40 PERCENT CHANCES ON THE WARM FRONT
FOR THE AFTERNOON. SHOULD STORMS DEVELOP...0-6KM SHEAR IS ONLY 25 KT
AT BEST WITH 0-3KM NEAR 20KT. THIS MEANS THE STORMS WILL PROBABLY BE
UNORGANIZED AND MOST LIKELY JUST HEAVY RAIN MAKERS GIVEN HIGH CAPE
AND NEAR 2 INCH PRECIPITABLE WATERS.
TONIGHT IS A BIT MORE INTERESTING. A CONVECTIVE COMPLEX APPEARS
LIKELY TO DEVELOP IN THE GRAND FORKS AREA IN THE EVENING AHEAD OF
THE SHORTWAVE. THIS CONVECTION...AIDED ALSO BY 700MB MOISTURE
TRANSPORT LIKE THE CONVECTION GOING OVER UPPER MI...SHOULD TRACK
EAST-SOUTHEAST INTO NORTHERN WI. THIS MEANS TAYLOR/CLARK COULD BE
IMPACTED BY THE COMPLEX AFTER MIDNIGHT. ADDITIONAL CONVECTION COULD
FORM ON THE NOSE OF 850MB MOISTURE TRANSPORT NORTH OF I-94 THIS
EVENING AS WELL. CANNOT RULE OUT SOME SEVERE WEATHER...LIKELY IN THE
FORM OF DAMAGING WINDS AND LARGE HAIL...ESPECIALLY AFTER MIDNIGHT
WHEN 0-6 KM SHEAR VALUES APPROACH 30-40 KT. THE REST OF THE AREA
SHOULD STAY MAINLY DRY...CAPPED AND WARM WITH A SOUTHERLY BREEZE
PERSISTING. LOW TEMPERATURES ARE LIKELY TO BE SIMILAR TO NOW GIVEN
SIMILAR CONDITIONS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 309 AM CDT MON AUG 26 2013
..HAZARDS..
1. HEAT...WHICH WILL PERSIST INTO TUESDAY. COLD FRONT COMES THROUGH
TUESDAY NIGHT WHICH SHOULD HELP ADVECT BOTH SOMEWHAT COOLER AND MORE
IMPORTANTLY DRIER AIR INTO THE AREA FOR WEDNESDAY. HEAT LOOKS TO
RETURN DURING LABOR DAY WEEKEND.
2. STORMS. THOSE ON TUESDAY COULD POSE A SEVERE AND HEAVY RAIN
THREAT NORTH OF I-94.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE CONTINUES TO SUGGEST THAT THE SUBTROPICAL HIGH
WILL RETROGRADE WESTWARD THROUGH THE WEEK...ENDING UP IN COLORADO ON
FRIDAY. THIS RETROGRESSION IS IN RESPONSE TO A SERIES OF SHORTWAVE
TROUGHS DROPPING INTO THE MID-ATLANTIC REGION ON THE EAST SIDE OF
THE RIDGE. AS WE HEAD INTO THE WEEKEND...THE SUBTROPICAL RIDGE WILL
SHIFT EAST IN RESPONSE TO WHAT LOOKS TO BE A VERY DEEP TROUGH FOR
THIS TIME OF YEAR COMING INTO THE PACIFIC NORTHWEST. IT SHOULD BE
NOTED THAT THE 26.00Z ECMWF THROWS A MAJOR CURVE BALL TO THE WEEKEND
PLAN...DEVIATING GREATLY FROM ITS PREVIOUS RUN IN SHOWING A TROUGH
DIGGING INTO THE WESTERN GREAT LAKES LATE SUNDAY. THE REASON IS
RELATED TO THIS TROUGH BEING STRONGER AND TRACKING FARTHER SOUTH
COMING OUT OF SOUTHWEST CANADA ON FRIDAY...COMPARED TO ITS PREVIOUS
RUN...THE 26.00Z GFS AND CANADIAN. NOT READY TO FULLY BUY INTO THE
26.00Z ECMWF QUITE YET BEFORE SEEING THE ECMWF ENSEMBLES AND ITS
NEXT RUN.
..DETAILS..
THE SURFACE OVER CENTRAL MN AT 12Z TUESDAY WILL GRADUALLY DROP
SOUTHEAST THROUGH TUESDAY AND TUESDAY NIGHT...IN RESPONSE TO THE
SHORTWAVE AND CONVECTION OVER NORTHERN WI/UPPER MI DROPPING
SOUTHEAST. HAVE KEPT SOME CHANCES ON TUESDAY NORTHEAST OF I-94 FOR
THE CONVECTION DROPPING SOUTHEAST...WHICH COULD BE SEVERE AS WELL.
THE REST OF THE AREA LOOKS CAPPED. TALKING ABOUT THE CAPPING...925MB
TEMPS ARE PROGGED TO REACH ABOUT 28C ON I-94 TO 30C IN NORTHEAST
IOWA. THESE READINGS SHOULD YIELD HIGHS RANGING FROM THE LOW TO
UPPER 90S...WARMEST IN RIVER VALLEYS. THE EXCESSIVE HEAT WARNING MAY
NEED EXPANSION INTO SOME OF NORTHEAST IOWA AND FAR SOUTHWEST WI IF
TEMP/DEWPOINT TRENDS CONTINUE. ALL CONVECTION LOOKS LIKE IT WILL BE
SOUTHEAST OF THE AREA FOR TUESDAY NIGHT...THUS WENT DRY THEN.
DRY CONDITIONS ARE EXPECTED FOR WEDNESDAY AND WEDNESDAY NIGHT AS
HIGH PRESSURE BUILDS OVER WISCONSIN AND MICHIGAN IN THE WAKE OF
TUESDAYS LOW AND COLD FRONTAL PASSAGE. 925MB TEMPS OF 24-26C STILL
SUPPORTS HIGHS IN THE MID 80S TO LOW 90S...THOUGH. DEWPOINTS MAY
STILL BE UP IN THE LOW 70S OVER NORTHEAST IOWA...BUT HEAT INDICES
ARE MORE AROUND 95 VERSUS THE 100-105 AS OF LATE.
THURSDAY THROUGH SATURDAY FEATURE A GRADUAL WARM ADVECTION
PATTERN...WHICH MEANS A RETURN FOR SOME CHANCES OF SHOWERS AND
THUNDERSTORMS. HIGHEST CHANCES ARE FORECAST THURSDAY NIGHT OVER
WISCONSIN WHERE THERE APPEARS TO BE A JUXTAPOSITION OF RIGHT
ENTRANCE REGION FORCING...A POSSIBLE SHORTWAVE MOVING THROUGH...AND
THE LOW LEVEL MOISTURE TRANSPORT. SOME OF THESE CHANCES OF SHOWERS
AND THUNDERSTORMS MAY BE ABLE TO BE BETTER REFINED...IN TERMS OF
DRYING SOME OUT...OVER THE COMING DAYS AS MODELS SETTLE INTO THE
TIMING OF THE WARM ADVECTION. ONCE THE WARM AIR COMES IN...WE WILL
HAVE TO BE CONCERNED WITH HEAT ADVISORIES...AS EVEN THE NEW 26.00Z
ECMWF SHOWS 925MB TEMPS APPROACHING 30C OVER WESTERN PORTIONS OF THE
FORECAST AREA LATE FRIDAY.
SUNDAY AND THE REST OF LABOR DAY WEEKEND FORECAST IS NOW UP IN THE
AIR DUE TO THE NEW 26.00Z ECMWF. PREVIOUSLY AND IN AGREEMENT WITH
THE 26.00Z GFS IT APPEARED MUCH OF THE AREA WOULD BE IN THE WARM
SECTOR...WITH 925MB TEMPS OF 29-32C WHICH COULD ALLOW FOR HIGHS
AROUND 100. IF THE NEW ECMWF IS RIGHT...WE GET A MOSTLY DRY COLD
FRONTAL PASSAGE ON SUNDAY WITH HIGHS MORE IN THE MID TO UPPER 80S.
MONDAY ENDS UP MUCH MUCH COOLER WITH HIGHS MOSTLY IN THE 60S.
COMPARE THIS TO ITS PREVIOUS 4 RUNS SHOWING 94-98 AT LA CROSSE FOR
MONDAY.
&&
.AVIATION...EARLY THIS MORNING
ISSUED AT 326 AM CDT MON AUG 26 2013
THE VALLEY HAS DECOUPLED IN THE MISSISSIPPI RIVER VALLEY EARLY THIS
MORNING. THIS HAS ALLOWED THE WINDS TO FALL BELOW 10 KNOTS.
MEANWHILE ON NOCTURNAL LOW LEVEL JET AND THE TIGHT PRESSURE GRADIENT
OVER THE AREA. RAP SOUNDINGS SUGGEST THE WINDS AT 1300 FEET JUST
ABOVE THE NOCTURNAL INVERSION ARE BLOWING OUT OF THE SOUTHWEST AT 40
TO 45 KNOTS. AS A RESULT...HAVE UPDATED THE KLSE TAF TO ADD LOW
LEVEL WIND SHEAR. THE WIND SHEAR WILL DISSIPATE QUICKLY AROUND
26.14Z IN RESPONSE TO WEAKENING PRESSURE GRADIENT AND LOW LEVEL
JET...AND DIURNAL MIXING BREAKING DOWN THE INVERSION.
&&
.CLIMATE...
ISSUED AT 346 PM CDT SUN AUG 25 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
034-042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ032-033-041.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ086-087-
094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-088-096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RIECK
CLIMATE...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
309 AM CDT MON AUG 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 309 AM CDT MON AUG 26 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER
THE PACIFIC NORTHWEST AND EASTERN PACIFIC...AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUES TO STREAM OUT OF BAJA CALIFORNIA...UP THROUGH THE DAKOTAS
AND INTO THE NORTHERN GREAT LAKES AROUND THE SUBTROPICAL RIDGE. ONE
SUCH SHORTWAVE COMBINED WITH 700MB MOISTURE TRANSPORT SUPPORTING
CONVECTION TRACKING ACROSS FAR NORTHERN WI AND UPPER MICHIGAN.
REGARDING MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED
VALUES OF 1.5-2 INCHES FROM EASTERN SOUTH DAKOTA INTO THE NORTHERN
GREAT LAKES. AIRMASS IS ALSO VERY WARM WITH 850MB TEMPS FROM 00Z
RAOBS OF 22-24C ACROSS THE FORECAST AREA AND 24-28C OVER THE
NORTHERN PLAINS. WITH THE FORECAST AREA IN THE WARM SECTOR...SOUTH
OF A WARM FRONT POSITIONED OVER FAR NORTHERN WI...A SOUTHERLY BREEZE
HAS ONLY ALLOWED TEMPS TO FALL INTO THE MID TO UPPER 70S. THIS SAME
SOUTHERLY BREEZE HAS ADVECTED IN SOME LOWER DEWPOINTS...WHICH HAVE
FALLEN INTO THE 60S...LOWEST IN THE SOUTHEAST HALF OF THE AREA. 00Z
DVN SOUNDING REALLY SHOWED THE DRIER AIR COMPARED TO MPX.
..MODEL VERIFICATION..
HAVE INCLUDED THIS SECTION AS IT HAS HIGH IMPORTANCE WITH THE
FORECAST OF HIGH TEMPERATURES AND CONVECTION. LOOKING AT 00Z RAOBS
FOR 925MB TEMPS AND COMPARING TO 25.00Z MODEL GUIDANCE...THE ECMWF
WAS THE BEST WITH ALMOST NO ERROR ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST. THE GFS WAS GENERALLY 1-2C TOO HIGH. LASTLY...THE
NAM/RAP WERE THE WORST...HAVING ERRORS ON THE ORDER OF 3-6C...
HIGHEST AT MSP. BECAUSE THE NAM/RAP WERE TOO HIGH...IT BROKE THE CAP
AND BROUGHT THE CONVECTION WAY TOO FAR SOUTH.
..HAZARDS..
1. HEAT. TEMPERATURES ARE LIKELY TO BE A FEW DEGREES HIGHER TODAY
AND WITH DEWPOINTS CLIMBING BACK INTO THE LOW 70S...HEAT INDICES
SHOULD TOP OUT IN THE 100-105 RANGE. THE HIGHEST HEAT INDICES LOOK
TO OCCUR FROM LAKE CITY DOWN TO LA CROSSE...AND HAVE UPGRADED THIS
AREA TO AN EXCESSIVE HEAT WARNING.
2. STORMS. SOME SEVERE POTENTIAL AFTER MIDNIGHT TONIGHT...MAINLY
ACROSS TAYLOR/CLARK COUNTIES. HAVE TO WATCH RAINFALL AMOUNTS TOO.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE SUGGESTS THE SUBTROPICAL RIDGING RETROGRADES
JUST SLIGHTLY WESTWARD DURING THE NEXT 24 HOURS. THE MAIN FEATURE OF
FOCUS IS A STRETCHED OUT SHORTWAVE IN THE MONSOONAL FLOW...LOCATED
FROM EASTERN UTAH INTO SOUTH CENTRAL WYOMING. MODELS BRING THIS
SHORTWAVE INTO THE DAKOTAS BY 00Z AND PERHAPS AS FAR EAST AS WESTERN
UPPER MI BY 12Z. THIS SHORTWAVE HELPS TO LIFT A SURFACE LOW SITTING
NEAR THE BLACK HILLS OF SOUTH DAKOTA TO NEAR MINNEAPOLIS BY 12Z TUE.
..DETAILS..
FOCUS FOR POTENTIAL CONVECTION TODAY WILL LIE ON THE LOCATION OF THE
WARM FRONT IN NORTHERN WI. FIRST OFF...THE CURRENT CONVECTION
CROSSING FAR NORTHERN WI AND UPPER MI COULD DROP INTO TAYLOR AND
POSSIBLY CLARK COUNTY BEFORE WEAKENING THIS MORNING. THE OUTFLOW
FROM THE CONVECTION SHOULD HELP PUSH THE FRONT SOUTH TOWARDS I-94
THIS AFTERNOON. THEN...THE NEXT QUESTION IS IF THE AIRMASS IS
CAPPED...WHICH ENTIRELY DEPENDS ON HOW WARM WE GET. THERE SHOULD BE
PLENTY OF SUN TODAY ACROSS THE FORECAST AREA WITH MAYBE A FEW STRAY
CIRRUS CLOUDS. ECMWF 925MB TEMPS ARE PROGGED ABOUT 1-2C HIGHER
COMPARED TO YESTERDAY...THUS ANTICIPATING HIGHS TO BE ABOUT 1-3F
HIGHER... YIELDING READINGS MAINLY IN THE LOW TO MID 90S. A FEW
SPOTS LIKE LSE COULD EVEN HIT THE UPPER 90S. ECMWF ALSO DID VERY
WELL WITH THE DEWPOINTS YESTERDAY AND SUGGESTS THEY SHOULD CLIMB
INTO THE LOW 70S IN THE AFTERNOON...DUE TO EVAPOTRANSPORATION AND
THE HIGHER MOISTURE TO OUR NORTHWEST SLIDING SOUTH. THE FORECAST
HIGHS AND DEWPOINTS WOULD SEEM TO POINT TO POTENTIAL FOR THE CAP TO
BREAK...THUS HAVE INCLUDED 20-40 PERCENT CHANCES ON THE WARM FRONT
FOR THE AFTERNOON. SHOULD STORMS DEVELOP...0-6KM SHEAR IS ONLY 25 KT
AT BEST WITH 0-3KM NEAR 20KT. THIS MEANS THE STORMS WILL PROBABLY BE
UNORGANIZED AND MOST LIKELY JUST HEAVY RAIN MAKERS GIVEN HIGH CAPE
AND NEAR 2 INCH PRECIPITABLE WATERS.
TONIGHT IS A BIT MORE INTERESTING. A CONVECTIVE COMPLEX APPEARS
LIKELY TO DEVELOP IN THE GRAND FORKS AREA IN THE EVENING AHEAD OF
THE SHORTWAVE. THIS CONVECTION...AIDED ALSO BY 700MB MOISTURE
TRANSPORT LIKE THE CONVECTION GOING OVER UPPER MI...SHOULD TRACK
EAST-SOUTHEAST INTO NORTHERN WI. THIS MEANS TAYLOR/CLARK COULD BE
IMPACTED BY THE COMPLEX AFTER MIDNIGHT. ADDITIONAL CONVECTION COULD
FORM ON THE NOSE OF 850MB MOISTURE TRANSPORT NORTH OF I-94 THIS
EVENING AS WELL. CANNOT RULE OUT SOME SEVERE WEATHER...LIKELY IN THE
FORM OF DAMAGING WINDS AND LARGE HAIL...ESPECIALLY AFTER MIDNIGHT
WHEN 0-6 KM SHEAR VALUES APPROACH 30-40 KT. THE REST OF THE AREA
SHOULD STAY MAINLY DRY...CAPPED AND WARM WITH A SOUTHERLY BREEZE
PERSISTING. LOW TEMPERATURES ARE LIKELY TO BE SIMILAR TO NOW GIVEN
SIMILAR CONDITIONS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 309 AM CDT MON AUG 26 2013
..HAZARDS..
1. HEAT...WHICH WILL PERSIST INTO TUESDAY. COLD FRONT COMES THROUGH
TUESDAY NIGHT WHICH SHOULD HELP ADVECT BOTH SOMEWHAT COOLER AND MORE
IMPORTANTLY DRIER AIR INTO THE AREA FOR WEDNESDAY. HEAT LOOKS TO
RETURN DURING LABOR DAY WEEKEND.
2. STORMS. THOSE ON TUESDAY COULD POSE A SEVERE AND HEAVY RAIN
THREAT NORTH OF I-94.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE CONTINUES TO SUGGEST THAT THE SUBTROPICAL HIGH
WILL RETROGRADE WESTWARD THROUGH THE WEEK...ENDING UP IN COLORADO ON
FRIDAY. THIS RETROGRESSION IS IN RESPONSE TO A SERIES OF SHORTWAVE
TROUGHS DROPPING INTO THE MID-ATLANTIC REGION ON THE EAST SIDE OF
THE RIDGE. AS WE HEAD INTO THE WEEKEND...THE SUBTROPICAL RIDGE WILL
SHIFT EAST IN RESPONSE TO WHAT LOOKS TO BE A VERY DEEP TROUGH FOR
THIS TIME OF YEAR COMING INTO THE PACIFIC NORTHWEST. IT SHOULD BE
NOTED THAT THE 26.00Z ECMWF THROWS A MAJOR CURVE BALL TO THE WEEKEND
PLAN...DEVIATING GREATLY FROM ITS PREVIOUS RUN IN SHOWING A TROUGH
DIGGING INTO THE WESTERN GREAT LAKES LATE SUNDAY. THE REASON IS
RELATED TO THIS TROUGH BEING STRONGER AND TRACKING FARTHER SOUTH
COMING OUT OF SOUTHWEST CANADA ON FRIDAY...COMPARED TO ITS PREVIOUS
RUN...THE 26.00Z GFS AND CANADIAN. NOT READY TO FULLY BUY INTO THE
26.00Z ECMWF QUITE YET BEFORE SEEING THE ECMWF ENSEMBLES AND ITS
NEXT RUN.
..DETAILS..
THE SURFACE OVER CENTRAL MN AT 12Z TUESDAY WILL GRADUALLY DROP
SOUTHEAST THROUGH TUESDAY AND TUESDAY NIGHT...IN RESPONSE TO THE
SHORTWAVE AND CONVECTION OVER NORTHERN WI/UPPER MI DROPPING
SOUTHEAST. HAVE KEPT SOME CHANCES ON TUESDAY NORTHEAST OF I-94 FOR
THE CONVECTION DROPPING SOUTHEAST...WHICH COULD BE SEVERE AS WELL.
THE REST OF THE AREA LOOKS CAPPED. TALKING ABOUT THE CAPPING...925MB
TEMPS ARE PROGGED TO REACH ABOUT 28C ON I-94 TO 30C IN NORTHEAST
IOWA. THESE READINGS SHOULD YIELD HIGHS RANGING FROM THE LOW TO
UPPER 90S...WARMEST IN RIVER VALLEYS. THE EXCESSIVE HEAT WARNING MAY
NEED EXPANSION INTO SOME OF NORTHEAST IOWA AND FAR SOUTHWEST WI IF
TEMP/DEWPOINT TRENDS CONTINUE. ALL CONVECTION LOOKS LIKE IT WILL BE
SOUTHEAST OF THE AREA FOR TUESDAY NIGHT...THUS WENT DRY THEN.
DRY CONDITIONS ARE EXPECTED FOR WEDNESDAY AND WEDNESDAY NIGHT AS
HIGH PRESSURE BUILDS OVER WISCONSIN AND MICHIGAN IN THE WAKE OF
TUESDAYS LOW AND COLD FRONTAL PASSAGE. 925MB TEMPS OF 24-26C STILL
SUPPORTS HIGHS IN THE MID 80S TO LOW 90S...THOUGH. DEWPOINTS MAY
STILL BE UP IN THE LOW 70S OVER NORTHEAST IOWA...BUT HEAT INDICES
ARE MORE AROUND 95 VERSUS THE 100-105 AS OF LATE.
THURSDAY THROUGH SATURDAY FEATURE A GRADUAL WARM ADVECTION
PATTERN...WHICH MEANS A RETURN FOR SOME CHANCES OF SHOWERS AND
THUNDERSTORMS. HIGHEST CHANCES ARE FORECAST THURSDAY NIGHT OVER
WISCONSIN WHERE THERE APPEARS TO BE A JUXTAPOSITION OF RIGHT
ENTRANCE REGION FORCING...A POSSIBLE SHORTWAVE MOVING THROUGH...AND
THE LOW LEVEL MOISTURE TRANSPORT. SOME OF THESE CHANCES OF SHOWERS
AND THUNDERSTORMS MAY BE ABLE TO BE BETTER REFINED...IN TERMS OF
DRYING SOME OUT...OVER THE COMING DAYS AS MODELS SETTLE INTO THE
TIMING OF THE WARM ADVECTION. ONCE THE WARM AIR COMES IN...WE WILL
HAVE TO BE CONCERNED WITH HEAT ADVISORIES...AS EVEN THE NEW 26.00Z
ECMWF SHOWS 925MB TEMPS APPROACHING 30C OVER WESTERN PORTIONS OF THE
FORECAST AREA LATE FRIDAY.
SUNDAY AND THE REST OF LABOR DAY WEEKEND FORECAST IS NOW UP IN THE
AIR DUE TO THE NEW 26.00Z ECMWF. PREVIOUSLY AND IN AGREEMENT WITH
THE 26.00Z GFS IT APPEARED MUCH OF THE AREA WOULD BE IN THE WARM
SECTOR...WITH 925MB TEMPS OF 29-32C WHICH COULD ALLOW FOR HIGHS
AROUND 100. IF THE NEW ECMWF IS RIGHT...WE GET A MOSTLY DRY COLD
FRONTAL PASSAGE ON SUNDAY WITH HIGHS MORE IN THE MID TO UPPER 80S.
MONDAY ENDS UP MUCH MUCH COOLER WITH HIGHS MOSTLY IN THE 60S.
COMPARE THIS TO ITS PREVIOUS 4 RUNS SHOWING 94-98 AT LA CROSSE FOR
MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1100 PM CDT SUN AUG 25 2013
SHRA/TS HAVE DEVELOPED ALONG A SFC BOUNDARY AS THE LOW LEVEL
MOISTURE TRANSPORT/JET HAVE INCREASED INTO IT. LATEST HRRR SHOWING A
CHANGE OF HEART WILL HOW FAR SOUTH THIS PCPN WILL PROGRESS...KEEPING
IT MOSTLY OVER NORTHERN/NORTHEAST WI THROUGH THE OVERNIGHT HOURS.
00Z NAM12 AND LATEST RAP13 ALSO FAVORING THIS NOW. 00Z MPX SOUNDING
LIKELY SHOWS THE REASON WHY...AS THE LOW LEVEL CAPPING INVERSION
REMAINED IN PLACE. HOW FAR SOUTH THE SHRA/TS WOULD MAKE IT WAS
ALREADY IN QUESTION...AND CONFIDENCE IS HIGHER THAT THEY WON/T MAKE
IT TO THE TAF SITES NOW.
THE SFC FRONT SHOULD NUDGE BACK NORTH ON MONDAY...AND WILL SERVE AS
A FOCUS FOR MORE SHRA/TS MONDAY AFTERNOON-NIGHT. HERE AGAIN...THERE
COULD BE A THREAT FOR PCPN AT THE TAF SITES...DEPENDING ON WHERE THE
BOUNDARY LAYS UP AND THE TRACK OF AN UPPER LEVEL DISTURBANCE. TRENDS
FAVOR KEEPING THE SHRA/TS TO THE NORTH FOR NOW.
&&
.CLIMATE...
ISSUED AT 346 PM CDT SUN AUG 25 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
034-042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ032-033-041.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ086-087-
094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-088-096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RIECK
CLIMATE...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1100 PM CDT SUN AUG 25 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 346 PM CDT SUN AUG 25 2013
MAIN FORECAST CONCERNS ARE ON SEVERE THUNDERSTORM POTENTIAL TONIGHT
THROUGH TUESDAY AND HEAT INDEX VALUES.
LATEST SURFACE OBSERVATIONS PLACED A WARM FRONT EXTENDING FROM
SOUTHEAST NORTH DAKOTA THROUGH NORTHERN MINNESOTA...STRETCHING
EAST OVER SOUTHERN LAKE SUPERIOR. WATER VAPOR IMAGERY AND RAP 500 MB
ANALYSIS SHOWED HIGH PRESSURE CENTERED ALONG THE KANSAS/MISSOURI
BORDER WITH A FLATTENING RIDGE EXTENDING NORTH INTO THE UPPER
MISSISSIPPI RIVER VALLEY. A FEW SUBTLE SHORTWAVES NOTED...THE FIRST
WAS LOCATED OVER THE EASTERN DAKOTAS AND ANOTHER...SLIGHTLY STRONGER
WAVE...WAS MOVING INTO EASTERN MONTANA. THE WARM FRONT AND THESE TWO
WAVES WILL BE THE MAIN FEATURES TO KEEP A CLOSE EYE ON THROUGH
MONDAY MORNING. ALSO...A PLUME OF MONSOONAL MOISTURE WAS STREAMING
NORTHWARD THROUGH THE DESERT SOUTHWEST AND INTO WESTERN
NEBRASKA/SOUTH DAKOTA...HEADING EAST.
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE WARM FRONT THIS
EVENING...THEN MOVE SOUTHWARD OVERNIGHT. IT APPEARS THAT THE STORMS
WILL INITIATE OVER EAST CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN
THEN SHIFT SOUTHWARD WITH TIME DURING THE OVERNIGHT HOURS
POTENTIALLY IMPACTING AREAS NORTH OF INTERSTATE 90. CAPE VALUES
ARE RATHER IMPRESSIVE LATE THIS AFTERNOON OVER THESE AREAS...WITH
TEMPERATURES IN THE UPPER 90S AND DEWPOINTS IN THE LOWER 70S
PRODUCING 3500 TO 4000 J/KG OF SURFACE BASED CAPE. SHEAR ISN/T
OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR VALUES OF AROUND 30
KTS...MAINLY NORTH OF INTERSTATE 94. HOWEVER...THE SHEAR IS FOCUSED
IN THE 0-3 KM LAYER WHICH WOULD FAVOR THE POTENTIAL FOR LINEAR STORM
STRUCTURES WITH DAMAGING WINDS. THE HIGH INSTABILITY OVER THE AREA
SHOULD OVERCOME THE LACK OF STRONG SHEAR...LEADING TO THE POTENTIAL
FOR SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS. STRONG
850 MB MOISTURE TRANSPORT FOCUSES INTO THE WARM FRONT TONIGHT WHICH
COULD POTENTIALLY LEAD TO REPEATED ROUNDS OF THUNDERSTORMS ALONG IT.
PRECIPITABLE WATER VALUES INCREASE TO 2.0 TO 2.3 INCHES
TONIGHT...WHICH IS AROUND 230 PERCENT OF NORMAL. ALSO...WARM CLOUD
DEPTHS INCREASE TO AROUND 4.7 KM. ANY THUNDERSTORMS THAT DEVELOP IN
THIS AIRMASS WILL BE VERY EFFICIENT RAIN PRODUCERS. THESE FACTORS
COULD LEAD TO FLASH FLOODING OVER PORTIONS OF NORTHERN AND NORTH
CENTRAL WISCONSIN TONIGHT INTO EARLY MONDAY MORNING. CONFIDENCE ON
SEVERE THUNDERSTORM POTENTIAL IS HIGHEST NORTH AND EAST OF
INTERSTATE 94 TONIGHT. A STRONG CAP ALONG AND SOUTH OF THESE AREAS
SHOULD LIMIT HOW FAR SOUTH CONVECTION CAN BUILD. CANNOT RULE OUT THE
STORMS MAKING IT TO THE INTERSTATE 90 CORRIDOR BUT THEY SHOULD
QUICKLY DISSIPATE IF THEY MAKE IT ANY FURTHER SOUTH AND ENCOUNTER
THE STRONG CAP.
SHOWERS AND STORMS SHOULD QUICKLY TAPER OFF EARLY MONDAY MORNING AS
MOISTURE TRANSPORT WEAKENS. DEPENDING ON HOW THE OVERNIGHT
CONVECTION PLAYS OUT...THE WARM FRONT LOOKS TO BE ORIENTED JUST
NORTH OF THE INTERSTATE 94 CORRIDOR BY LATE MONDAY MORNING INTO
MONDAY AFTERNOON. MLCAPE VALUES INCREASE INTO THE 2000 TO 3500 J/KG
RANGE ALONG THE FRONT BY MID AFTERNOON ON MONDAY. 0-6 KM BULK SHEAR
VALUES HOVER AROUND 30 KTS OVER MUCH OF NORTHERN AND CENTRAL
WISCONSIN MONDAY AFTERNOON INTO MONDAY EVENING WHICH WOULD FAVOR
SEVERE MULTICELL STORMS. WITH THE HIGH CAPE VALUES NEAR THE WARM
FRONT...CANNOT RULE OUT A FEW SUPERCELL STRUCTURES ESPECIALLY OVER
NORTHWEST INTO NORTH CENTRAL WISCONSIN. ALSO FORECAST MODELS SUGGEST
THERE COULD BE JUST ENOUGH 0-1 KM SHEAR TO SUPPORT AN ISOLATED
TORNADO OR TWO NEAR THE WARM FRONT. OTHERWISE...THE STORMS WILL BE
CAPABLE OF PRODUCING LARGE HAIL...DAMAGING WINDS...AND HEAVY
RAINFALL. THE SHOWERS AND STORMS WILL CONTINUE INTO MONDAY NIGHT
WITH THE HIGHEST CHANCES MAINLY ALONG AND NORTHEAST OF INTERSTATE
94.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 346 PM CDT SUN AUG 25 2013
SHOWERS AND STORMS WILL BE ONGOING TUESDAY MORNING...MAINLY ALONG
AND EAST OF THE MISSISSIPPI RIVER. A WEAK COLD FRONT IS EXPECTED TO
SWEEP ACROSS THE REGION TUESDAY AFTERNOON. A FEW SHOWERS AND STORMS
CANNOT BE RULED OUT ALONG THE FRONT TUESDAY AFTERNOON INTO TUESDAY
EVENING...BUT IT APPEARS A CAP WILL HOLD STRONG FOR AREAS WEST OF
THE MISSISSIPPI RIVER...WITH A CHANCE OF SHOWERS AND STORMS OVER
MUCH OF WESTERN INTO CENTRAL WISCONSIN. 925MB TEMPERATURES COOL INTO
THE 22 TO 25 C RANGE IN THE WAKE OF THE FRONT. SO WE SHOULD SEE A
VERY SMALL RELIEF FROM THE HEAT WITH HEAT INDEX VALUES FALLING INTO
THE MID TO UPPER 90S. SURFACE HIGH PRESSURE SETTLES OVERHEAD ON
THURSDAY BRINGING SOME SLIGHTLY COOLER AIR WITH IT...WITH 925MB
TEMPERATURES FALLING TO AROUND 23 C...PRODUCING HIGHS IN THE UPPER
80S TO AROUND 90. THE HIGH SLIDES OFF TO THE EAST ON FRIDAY AS A
WARM FRONT PUSHES EAST OUT OF THE NORTHERN/CENTRAL PLAINS. WEAK
SHORTWAVES ARE EXPECTED TO INTERACT WITH THE FRONT BRINGING CHANCES
FOR SHOWERS AND STORMS TO THE AREA FROM THURSDAY AFTERNOON THROUGH
FRIDAY NIGHT. MODEL SOLUTIONS START TO DIVERGE SATURDAY INTO SUNDAY
ON TIMING OF THESE SHORTWAVES SO CONFIDENCE LOW ON PRECIPITATION
CHANCES SATURDAY INTO SUNDAY. TEMPERATURES ARE EXPECTED TO WARM
SLIGHTLY FOR THE WEEKEND WITH HIGHS CLIMBING INTO THE UPPER 80S TO
LOWER 90S...DEPENDING ON TIMING OF THE SHORTWAVES AND ANY SHOWERS
AND STORM ASSOCIATED WITH THEM. 850MB TEMPERATURE STANDARDIZED
ANOMALIES HOVER AROUND PLUS 2 THIS WEEKEND THROUGH EARLY NEXT WEEK
SO WILL HAVE TO KEEP A CLOSE WATCH ON THE POTENTIAL FOR HEAT
HEADLINES WITH THE POSSIBILITY OF SEEING NEAR RECORD HEAT FOR THESE
DATES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1100 PM CDT SUN AUG 25 2013
SHRA/TS HAVE DEVELOPED ALONG A SFC BOUNDARY AS THE LOW LEVEL
MOISTURE TRANSPORT/JET HAVE INCREASED INTO IT. LATEST HRRR SHOWING A
CHANGE OF HEART WILL HOW FAR SOUTH THIS PCPN WILL PROGRESS...KEEPING
IT MOSTLY OVER NORTHERN/NORTHEAST WI THROUGH THE OVERNIGHT HOURS.
00Z NAM12 AND LATEST RAP13 ALSO FAVORING THIS NOW. 00Z MPX SOUNDING
LIKELY SHOWS THE REASON WHY...AS THE LOW LEVEL CAPPING INVERSION
REMAINED IN PLACE. HOW FAR SOUTH THE SHRA/TS WOULD MAKE IT WAS
ALREADY IN QUESTION...AND CONFIDENCE IS HIGHER THAT THEY WON/T MAKE
IT TO THE TAF SITES NOW.
THE SFC FRONT SHOULD NUDGE BACK NORTH ON MONDAY...AND WILL SERVE AS
A FOCUS FOR MORE SHRA/TS MONDAY AFTERNOON-NIGHT. HERE AGAIN...THERE
COULD BE A THREAT FOR PCPN AT THE TAF SITES...DEPENDING ON WHERE THE
BOUNDARY LAYS UP AND THE TRACK OF AN UPPER LEVEL DISTURBANCE. TRENDS
FAVOR KEEPING THE SHRA/TS TO THE NORTH FOR NOW.
&&
.CLIMATE...
ISSUED AT 346 PM CDT SUN AUG 25 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
032>034-041>044-053>055-061.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ079-
086>088-094>096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....RIECK
CLIMATE......WETENKAMP
AREA FORECAST DISCUSSION
NWS GOODLAND KS
520 AM MDT MON AUG 26 2013
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 243 AM MDT MON AUG 26 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW LARGE H5 598DM RIDGE
STILL IN PLACE ACROSS THE CENTRAL CONUS. WHILE THERE IS WEAK
ENERGY ROTATING AROUND THE WEST SIDE OF THE RIDGE THAT CONTINUES TO
INITIATE SHOWER/THUNDERSTORM ACTIVITY OVER THE MOUNTAINS...BEYOND
HIGH CLOUDS MOVING ACROSS THE WESTERN PART OF OUR CWA THESE WEAK
WAVES WILL NOT HAVE ANY INFLUENCE ON OUR WEATHER LOCALLY. WITH
THIS VERY STAGNANT PATTERN IN PLACE FORECAST FOCUS CONTINUES TO
BE ON HOT TEMPERATURES AND MARGINAL FIRE WEATHER CONDITIONS.
TIGHT GRADIENT IS STILL IN PLACE ACROSS OUR CWA ON EASTER EDGE OF
TEE TROUGH...HOWEVER THE MAIN TROUGH AXIS IS BEGINNING OT SHIFT
CLOSER TO THE KS/CO BORDER WHICH SHOULD HELP RELAX THE GRADIENT
ACROSS THE NW HALF OF OUR CWA. AS WOULD BE EXPECTED WITH LESS
GRADIENT IN THE NW PART OF OUR CWA...SHORT RANGE MODELS ARE
BACKING OFF ON WINDS ACROSS THE WEST...WITH GUSTY WINDS MAINLY
ACROSS OUR EASTERN CWA. LOWEST RH VALUES SHOULD BE ACROSS THE WEST
AS HAS BEEN THE CASE THE LAST FEW DAYS...AND ARE ALREADY MARGINAL
FOR RFW. THE CHANCE FOR RH/WIND CROSSOVER IS VERY LOW...SO FIRE
WEATHER HIGHLIGHT WILL NOT BE NECESSARY.
REGARDING TEMPERATURES...NAM/GFS/ECMWF ALL SHOW VERY SIMILAR
AIR MASS IN PLACE THROUGH TUESDAY WHICH MEAN THERE SHOULDNT BE A
LOT OF VARIANCE FROM UPPER 90S/LOW 100S. BETTER MIXING COULD
RESULT IN NEAR RECORD HIGHS AT A FEW LOCATIONS. I DECIDED TO KEEP
ONGOING FORECAST WITHIN A DEGREE OR TWO OF PERSISTENCE WITH LITTLE
EXPECTED TO CHANGE. THROUGH TUESDAY NIGHT. BY WEDNESDAY A
SHORTWAVE TROUGH/MID LEVEL VORTICITY MAX WILL ROTATE FROM THE
SOUTHERN PLAINS AND ACROSS WESTERN KANSAS OUT OF THE SOUTH. WHILE
LARGE SCALE ASCENT AND ELEVATED INSTABILITY ASSOCIATED WITH A
MID LEVEL COLD POOL WILL MOVE OVER THE CWA...THERE IS A
SIGNIFICANTLY DRY AIR MASS IN PLACE. BEYOND AN INCREASE IN CLOUDS I
AM NOT ANTICIPATING ANY PRECIP WITH THIS FEATURE. THIS WILL HELP
REDUCE TEMPS OVER THE CWA BY ABOUT 5-7F FOR MOST LOCATIONS...WHICH
IS A SMALL CONCESSION SINCE THIS IS STILL WELL ABOVE NORMAL.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 243 AM MDT MON AUG 26 2013
THE UPPER LEVEL RIDGE WILL PERSIST THROUGH THE EXTENDED PERIOD. THE
WARMEST 850 MB TEMPERATURES WILL BE ON FRIDAY AND SATURDAY RESULTING
IN HIGH TEMPERATURES IN THE UPPER 90S TO NEAR 100 DEGREES BOTH DAYS.
DIFFERENCES IN MEDIUM RANGE MODELS EMERGE OVER THE WEEKEND WITH THE
CHARACTER AND POSITION OF THE UPPER LEVEL RIDGE AND THE EASTWARD
PROGRESSION OF PACIFIC NORTHWEST TROUGH. GFS ENSEMBLE MEAN IS THE
MOST PROGRESSIVE SHIFTING BOTH FEATURES EASTWARD AND PLACING THE
AREA IN SOUTHWESTERLY FLOW ALOFT. IN CONTRAST ECMWF HOLDS THE RIDGE
OVER THE AREA WITH A SLIGHT DEAMPLIFICATION AS A SHORTWAVE TROUGH
MOVES EASTWARD ACROSS THE NORTHERN PLAINS. IN EITHER SCENARIO...A
GENERALLY DRY PATTERN WITH ABOVE NORMAL TEMPERATURES ARE LIKELY TO
PERSIST THROUGH THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 519 AM MDT MON AUG 26 2013
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD. THE WIND WILL
INCREASE AND BECOME GUSTY BY LATE MORNING PERSISTING THROUGH EARLY
EVENING. GUSTS TO AROUND 30 KNOTS WILL BE POSSIBLE DURING THIS
PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BRB
AVIATION...BRB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1026 AM EDT MON AUG 26 2013
.SYNOPSIS...
WARMER AND MORE HUMID AIR FOR MUCH OF THE WEEK. A COLD FRONT WILL
BRING SHOWERS AND STORMS TUESDAY AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH 1030AM UPDATE...MADE MANY SMALL TWEAKS TO THE FORECAST.
UPDATED HOURLY AND MAXIMUM TEMPERATURES WITH LATEST GFSLAMP
GUIDANCE...WHICH SO FAR HAS HAD A GOOD HANDLE OF TEMPERATURE
TRENDS. ALSO BACKED OFF SLIGHTLY ON THE HIGH CIRRUS MOVING IN.
WITH LATEST RUNS OF THE HRRR AND RUC SHOWING THAT ANY
PRECIPITATION THAT AFFECTS THE AREA SHOULD ARRIVE MORE TOWARDS
THE EVENING...HAVE ALSO BACKED OFF POPS SLIGHTLY DURING THE
AFTERNOON TIME PERIOD.
PREVIOUS DISC...AREA LIES ON THE EASTERN PERIPHERY OF STRONG
RIDGE OVER THE CENTRAL STATES. BECAUSE OF THIS...THE DISTRICT IS
IN A PRECARIOUS POSITION WITH NORTHWEST FLOW ALOFT. THIS WILL
BECOME IMPORTANT AS THE WEEK PROGRESSES.
FOR TODAY...THE UPPER LEVEL RIDGE HOLDS FIRM INTO THE AFTERNOON
THEN BEGINS TO RETROGRADE AS A SHORTWAVE TROUGH DIVES DOWN
THROUGH THE GREAT LAKES. THE STRONGEST PART OF THE SHORTWAVE...AND
DEEPEST MOISTURE...WILL MOVE EAST LATE THIS AFTERNOON. WAVE MAY
BE CLOSE ENOUGH TO SPARK A SHOWER OR STORM ACROSS THE NORTH AS
THE EVENING APPROACHES.
HUMIDITY LEVELS AND TEMPERATURES WILL BE ON THE RISE TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
AT THIS POINT...HAVE LOW CONFIDENCE ON HOW MUCH ACTIVITY WILL
MOVE THROUGH TONIGHT. AS MENTIONED PREVIOUSLY...MOST OF THE UPPER
LEVEL ENERGY AND DEEP MOISTURE WILL MOVE EAST OF THE AREA.
ADDITIONALLY...ATMOSPHERE STABILIZES AND THE LOW LEVEL JET DIVES
INTO EASTERN PA. MODELS ARE INDICATING SOME ACTIVITY HOLDING
TOGETHER OVERNIGHT AS PART OF THE UPPER LEVEL WAVE STRETCHES
WESTWARD. LATEST HIRES MODEL DATA IS SHOWING A LINE OF
SHOWERS/STORMS DEVELOPING ALONG LAKE ERIE THIS EVENING AND THEN
MOVING SOUTHWARD INTO EARLY TUESDAY MORNING. LOW LEVEL MOISTURE
WILL POOL OVER THE UPPER OHIO VALLEY AHEAD OF THE WAVE...BUT WOULD
THINK THAT ACTIVITY WILL DIMINISH AS IT MOVES SOUTHWARD. WILL
CONTINUE WITH THE MENTION OF SCHC/CHC POPS TONIGHT WITH THUNDER
BECOMING LESS PREVALENT LATE TONIGHT.
THIS FIRST WAVE WILL BE OUT OF THE PICTURE TUESDAY MORNING...
ALLOWING FOR A BREAK IN THE ACTIVITY. THANKS TO TONIGHT`S
WAVE...THE RIDGE WILL FURTHER RETROGRADE...PUTTING THE REGION IN
THE PATH OF A SECOND WAVE MOVING SOUTHEASTWARD TUESDAY AFTERNOON.
ATMOSPHERE BECOMES VERY UNSTABLE TUESDAY WITH CAPES OF 2000-3000
J/KG AND LI`S TO AROUND -5. THE K INDEX IS IN THE MID 30S AND THE
MDPI IS AROUND 1. IN ADDITION TO THE ENERGETIC ATMOSPHERE...
SURFACE TDS WILL BE IN THE LOWER 70S LEADING TO PWATS NEAR 1.7. IF
CONVECTION CAN GET GOING...WIND AND HEAVY RAIN WILL BE A THREAT. A
LIMITING FACTOR...PARTICULARLY EARLIER IN THE DAY...WILL BE
RESIDUAL CLOUD COVER. CONVECTIVE TEMPS REMAIN IN THE MID 80S
TUESDAY AND CLOUD COVER MAY MAKE REACHING THESE TEMPS DIFFICULT.
TUESDAYS SHORTWAVE WILL MOVE EASTWARD AND BE FOLLOWED BY ANOTHER
WAVE TUESDAY NIGHT. TUESDAY NIGHT`S WAVE COULD POSSIBLY DEVELOP AN
MCS OVER THE UPPER GREAT LAKES WHICH WOULD DROP DOWN THROUGH THE
AREA. AT THIS POINT...THINK THE GREATER THREAT TUESDAY NIGHT/EARLY
WED WOULD BE WATER RATHER THAN WIND. INSTABILITY WANES...BUT WITH
PWATS NEAR 2 INCHES...ANY CONVECTION WILL PRODUCE HEAVY DOWNPOURS.
THE THREAT FOR STRONG STORMS WILL CONTINUE THROUGH WEDNESDAY AS A
COLD FRONT SINKS THROUGH THE UPPER OHIO VALLEY.
TUESDAY AND WEDNESDAY WILL NEED TO BE CLOSELY MONITORED. IN
GENERAL...WHEN THE AREA LIES ON THE EASTERN EDGE OF A STRONG
RIDGE CAUSING NORTHWEST FLOW ALOFT...OUR WEATHER GETS VERY ACTIVE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
COLD FRONT WILL CLEAR THE AREA WEDNESDAY NIGHT. HIGH PRESSURE WILL
RESUME CONTROL FOR THE REMAINDER OF THE LONG TERM.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
GENL VFR CONDS ARE EXPD THRU THIS EVE WITH INCRG MID/HIGH CLDS.
AREAS OF SHWRS AND TSTMS ASSOCIATED WITH UPR LVL DISTURBANCES WL
DROP SE ACRS THE ERN GT LKS TDA AND TNGT...HOWEVER MUCH OF THIS
SHOULD STAY N AND E OF THE PORTS. FKL/DUJ HAVE THE BEST CHC AT
SEEING A SHWR OR TSTM THIS EVE SO INCLUDED A VCSH MENTION THERE.
LWR SHWR/TSTM CHCS ELSW TNGT...SO NO MENTION OF PCPN AT OTHER
PORTS. FKL/DUJ MAY ALSO SEE A PD OF MVFR CONDS NR SUNRISE TUE
MRNG.
.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
RSTRNS ARE PSBL IN SHWRS/TSTMS TUE AFTN THRU WED AS A CDFNT
CROSSES THE RGN. VFR RTNS WITH HIGH PRES THU AND FRI.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1116 AM EDT MON AUG 26 2013
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 344 AM EDT MON AUG 26 2013
WARM AND HUMID DAYS WILL CONTINUE TODAY AND TUESDAY. HOWEVER A COLD
FRONT WILL PASS THROUGH THE REGION TUESDAY NIGHT...BRINGING A GOOD
CHANCE FOR STORMS AS WELL AS LESS HUMID AIR INTO THE AREA BY
WEDNESDAY.
TEMPERATURES ARE EXPECTED TO REMAIN 85 TO 90 INTO THE WEEKEND
WITH ANOTHER CHANCE FOR RAIN BY FRIDAY NIGHT INTO SUNDAY.
&&
.UPDATE...
ISSUED AT 1115 AM EDT MON AUG 26 2013
THE CONVECTION THIS MORNING IS EXPECTED TO WEAKEN INTO THIS
AFTERNOON AS THE SHORTWAVE THAT HELPED CREATE IT MOVE EAST OVER
CENTRAL LOWER MICHIGAN RESULTING IN DPVA OVER OUR AREA. THE
OUTFLOW BOUNDARY IS MOVING INTO MORE STABLE AIR SO I DO NOT THINK
THERE WILL BE SIGNIFICANT REDEVELOPMENT SOUTH OF INTERSTATE 96
THIS AFTERNOON. SO I FEATURE DECREASING POPS DURING THE AFTERNOON
TO SHOW THE DECREASING THREAT FOR STORMS INTO THE LATE AFTERNOON.
UPDATE ISSUED AT 853 AM EDT MON AUG 26 2013
I UPDATED THE GRIDS AND ZONE FORECAST TO TRACK THE LINE OF
THUNDERSTORMS SOUTHEAST ACROSS THE CENTRAL CWA BASED ON A
COMBINATION OF THE TIMING TOOL AND THE HRRR RUC (10Z). THIS WOULD
BRING THE STORMS TO NEAR LANSING AROUND 1045 AM THIS MORNING. THE
LOW LEVEL JET SPEED MAX IS JUST IN FRONT OF THIS LINE OF STORMS.
IT WEAKENS AS THE DAY PROGRESSES AND SHIFTS SOUTHEAST (RAP 11Z).
BY NOON THE CORE IS ONLY 30 KNOTS AND OVER MONTCALM AND GRATIOT
COUNTIES SO THE STORMS SHOULD HAVE A HARD TIME GETTING TO MUCH
FARTHER SOUTH THAN THAT.
I WILL HAVE TO WATCH WHAT HAPPENS FOR THIS AFTERNOON AS THE
VERTICAL TOTALS SOUTH OF ROUTE 10 ARE NEAR 29C AND THE 850 TO 500
MB LAPSE RATE IS NEAR 8C. SEEMS MORE STORMS ARE POSSIBLE THIS
AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 344 AM EDT MON AUG 26 2013
SEVERAL CHALLENGES IN THE SHORT TERM. FIRST WILL BE JUST HOW HOT
THE REGION GETS. THIS WILL LARGELY DEPEND ON THE AMOUNT OF SUNSHINE
WE GET...OR IF THE DEBRIS CLOUDS WIN OUT. SECONDLY WILL BE THE
INCREASING CHANCES FOR SHOWERS AND STORMS AS THE UPPER RIDGE WEAKENS
AND DRIFTS SOUTH WITH TIME.
HAVE DECIDED TO HOLD FAIRLY CONSISTENT WITH THE TEMP FORECAST
DESPITE A LARGE AREA OF DEBRIS CLOUDS UPSTREAM EARLY THIS MORNING.
MID/HI CLOUDS WILL SPREAD IN FROM THE THUNDERSTORM CLUSTER THAT
WAS OVER THE NORTHERN GREAT LAKES. IT APPEARS THERE IS ENOUGH
RIDGING IN PLACE TO THIN THESE CLOUDS WITH TIME AND MAX TEMPS
AROUND 90 STILL LOOK OK FOR TODAY. EXPECT A SIMILAR SETUP INTO
TUESDAY...AND HAVE MAINTAINED MAX TEMPS AROUND 90 AGAIN. TUESDAY
SHOULD BE THE WARMEST DAY CONSIDERING DEW POINTS WILL BE
HIGHER...DRIVING HEAT INDEX READINGS INTO THE MID AND UPPER 90S.
TEMPS WILL ONLY BE A COUPLE DEGREES COOLER ON WED AS A FRONT
PASSES THROUGH...ALSO BRINGING SLIGHTLY LOWER DEW POINTS.
AS FOR SHOWERS AND STORMS...THE CENTER OF THE UPPER HIGH WILL BE
NEAR KANSAS CITY TODAY AND IT WILL SLOWLY SINK SOUTH THROUGH WED.
IT/S INFLUENCES WILL SLOWLY LOSE ITS GRIP ON THE GREAT LAKES...AND
THE RING OF CONVECTION AROUND THIS RIDGE SHOULD GRADUALLY EASE INTO
THE CWA THROUGH THE SHORT TERM. AT THE SURFACE THE MODELS ARE IN
GOOD AGREEMENT PUSHING A COLD FRONT THROUGH HERE TUESDAY NIGHT.
THE BEST JET DYNAMICS STAYS TO OUR NORTH AND WEST TODAY AND TONIGHT.
SO FEEL ANY SHOWERS AND STORMS THAT REACHES THE GRR CWA WILL BE IN A
WEAKENING STATE AS THEY RUN AWAY FROM THE BEST DYNAMICS AND INTO THE
RIDGE. HOWEVER A LOW LEVEL JET IS POISED TO PUSH IN AHEAD OF THE
COLD FRONT BY TUESDAY AFTERNOON INTO THE EVENING. THIS APPEARS TO
BE THE BEST CHANCE FOR PCPN AND HAVE RAISED POPS TO LIKELY ACROSS
MUCH OF THE CWA. SEVERE STORMS WILL BE POSSIBLE FROM ROUGHLY MID
AFTERNOON THROUGH ABOUT MIDNIGHT. DAMAGING WIND WILL BE THE MAIN
THREAT WILL SOME LARGE HAIL POSSIBLE.
THE FRONT SHOULD BE THROUGH THE CWA BY WED MORNING AND HAVE
MAINTAINED A DRY FORECAST. NOT MUCH COOLER BEHIND THE FRONT...WITH
HEAT INDEX READINGS ONLY RETREATING TO AROUND 90.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 344 AM EDT MON AUG 26 2013
MODELS ARE CONSISTENT IN SHOWING THE PLAINS RIDGE HANGING ON THROUGH
THE LONG TERM WITH NORTHWEST FLOW IN PLACE OVER THE GREAT LAKES.
500MB HEIGHTS WILL BE HIGH ENOUGH (580S DM/S) AND 850MB TEMPS WARM
ENOUGH (+16C TO +20C) THAT HIGH TEMPS WILL REMAIN IN THE MIDDLE 80S
TO AROUND 90.
MAIN ISSUE WILL BE TRYING TO TIME ANY PRECIPITATION INTO THE AREA AS
SHORTWAVE ENERGY SLIDES SOUTHEAST IN THE NORTHWEST UPPER FLOW.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT LOOK DRY WITH HIGH PRESSURE
IN PLACE BEHIND WEDNESDAY/S FROPA. FRIDAY AND FRIDAY NIGHT...BOTH
THE GFS AND THE ECMWF ARE INSISTENT THAT A WARM FRONT WILL BE NEARBY
WITH PRECIPITATION IN THE AREA. NOT CONFIDENT IN THIS SCENARIO...SO
ONLY HAVE 20 PCT POPS IN THE FORECAST. KEPT THE FORECAST DRY
SATURDAY AND SATURDAY NIGHT WITH ANOTHER 20 PCT CHANCE FOR SHOWERS
AND STORMS ON SUNDAY. THE ECMWF AND GFS DIVERGE ON SURFACE FEATURES
FOR NEXT SUNDAY. OPTED TO FOLLOW THE GFS HERE AND HAVE A SMALL
CHANCE IN THE FORECAST AS ANOTHER WARM FRONT IS PROGD IN THE AREA.
OVERALL..THE LONG TERM PERIOD LOOKS TO REMAIN WARM WITH ABOVE NORMAL
TEMPERATURES. PRECIPITATION CHANCES ARE A TOUGH CALL...BUT IT
APPEARS SMALL CHANCES FOR SHOWERS AND STORMS EXIST BOTH FRIDAY AND
SUNDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 720 AM EDT MON AUG 26 2013
VFR WEATHER IS EXPECTED THIS MORNING...WITH AN INCREASING
SOUTHWEST WIND. BY LATE MORNING...SOUTHWEST WINDS OF 10-20 KNOTS
SHOULD BE COMMON. MID AND HIGH CLOUDS WILL CONTINUE TO DRIFT IN
FROM THE NORTH...BASES SHOULD BE ABOVE 12000FT.
STORMS TO THE NORTH THIS MORNING MAY EVENTUALLY MAKE THERE WAY
INTO THE NORTHERN TAF SITES THIS AFTERNOON. CONFIDENCE IN THIS
OCCURRING IS NOT HIGH THOUGH AND ONLY INCLUDED VICINITY THUNDER
WORDING FOR THIS AFTERNOON.
CEILINGS OF 5000-10000FT ARE EXPECTED TONIGHT WITH THE POTENTIAL
OF ADDITIONAL STORMS ROLLING IN LATE. STORMS WILL MOVE ACROSS
MINNESOTA AND WISCONSIN THIS EVENING AND MAY PUSH INTO THE TAF
SITES LATE TONIGHT. CONFIDENCE IN THE EVOLUTION REMAINS LOW AND
GIVEN ITS THEN END OF THE FORECAST PERIOD DID NOT INCLUDE THUNDER
FOR LATE TONIGHT YET.
&&
.MARINE...
ISSUED AT 344 AM EDT MON AUG 26 2013
SOUTHWEST FLOW WILL CONTINUE TO BRING SCA CONDITIONS TODAY. HOWEVER
AS THE FRONT APPROACHES WINDS WILL SLOWLY WEAKEN. FEEL CONDITIONS
WILL IMPROVE TOWARD EVENING...AND AS SUCH...MOVED UP THE ENDING OF
THE SCA.
ANOTHER PERIOD OF HIGHER WINDS AND WAVES WILL OCCUR BEHIND THE FRONT
FOR LATE TUESDAY NIGHT INTO WEDNESDAY WHEN ANOTHER SCA MAY BE NEEDED
WITH A NORTHERLY FLOW.
&&
.HYDROLOGY...
ISSUED AT 344 AM EDT MON AUG 26 2013
MOST AREAS SHOULD SEE BETWEEN A HALF INCH AND ONE INCH OF RAIN
THROUGH TUESDAY NIGHT. THE HIGHEST TOTALS SHOULD BE ACROSS THE
NORTHERN CWA. THIS HAS BEEN THE DRIER AREA...A SHOULD BE ABLE TO
HANDLE THIS AMOUNT OF RAIN. LOCALIZED POOR DRAINAGE FLOODING WILL BE
POSSIBLE IN PERSISTENT STORMS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 6 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...DUKE
AVIATION...DUKE
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
854 AM EDT MON AUG 26 2013
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 344 AM EDT MON AUG 26 2013
WARM AND HUMID DAYS WILL CONTINUE TODAY AND TUESDAY. HOWEVER A COLD
FRONT WILL PASS THROUGH THE REGION TUESDAY NIGHT...BRINGING A GOOD
CHANCE FOR STORMS AS WELL AS LESS HUMID AIR INTO THE AREA BY
WEDNESDAY.
TEMPERATURES ARE EXPECTED TO REMAIN 85 TO 90 INTO THE WEEKEND
WITH ANOTHER CHANCE FOR RAIN BY FRIDAY NIGHT INTO SUNDAY.
&&
.UPDATE...
ISSUED AT 853 AM EDT MON AUG 26 2013
I UPDATED THE GRIDS AND ZONE FORECAST TO TRACK THE LINE OF
THUNDERSTORMS SOUTHEAST ACROSS THE CENTRAL CWA BASED ON A
COMBINATION OF THE TIMING TOOL AND THE HRRR RUC (10Z). THIS WOULD
BRING THE STORMS TO NEAR LANSING AROUND 1045 AM THIS MORNING. THE
LOW LEVEL JET SPEED MAX IS JUST IN FRONT OF THIS LINE OF STORMS.
IT WEAKENS AS THE DAY PROGRESSES AND SHIFTS SOUTHEAST (RAP 11Z).
BY NOON THE CORE IS ONLY 30 KNOTS AND OVER MONTCALM AND GRATIOT
COUNTIES SO THE STORMS SHOULD HAVE A HARD TIME GETTING TO MUCH
FARTHER SOUTH THAN THAT.
I WILL HAVE TO WATCH WHAT HAPPENS FOR THIS AFTERNOON AS THE
VERTICAL TOTALS SOUTH OF ROUTE 10 ARE NEAR 29C AND THE 850 TO 500
MB LAPSE RATE IS NEAR 8C. SEEMS MORE STORMS ARE POSSIBLE THIS
AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 344 AM EDT MON AUG 26 2013
SEVERAL CHALLENGES IN THE SHORT TERM. FIRST WILL BE JUST HOW HOT
THE REGION GETS. THIS WILL LARGELY DEPEND ON THE AMOUNT OF SUNSHINE
WE GET...OR IF THE DEBRIS CLOUDS WIN OUT. SECONDLY WILL BE THE
INCREASING CHANCES FOR SHOWERS AND STORMS AS THE UPPER RIDGE WEAKENS
AND DRIFTS SOUTH WITH TIME.
HAVE DECIDED TO HOLD FAIRLY CONSISTENT WITH THE TEMP FORECAST
DESPITE A LARGE AREA OF DEBRIS CLOUDS UPSTREAM EARLY THIS MORNING.
MID/HI CLOUDS WILL SPREAD IN FROM THE THUNDERSTORM CLUSTER THAT
WAS OVER THE NORTHERN GREAT LAKES. IT APPEARS THERE IS ENOUGH
RIDGING IN PLACE TO THIN THESE CLOUDS WITH TIME AND MAX TEMPS
AROUND 90 STILL LOOK OK FOR TODAY. EXPECT A SIMILAR SETUP INTO
TUESDAY...AND HAVE MAINTAINED MAX TEMPS AROUND 90 AGAIN. TUESDAY
SHOULD BE THE WARMEST DAY CONSIDERING DEW POINTS WILL BE
HIGHER...DRIVING HEAT INDEX READINGS INTO THE MID AND UPPER 90S.
TEMPS WILL ONLY BE A COUPLE DEGREES COOLER ON WED AS A FRONT
PASSES THROUGH...ALSO BRINGING SLIGHTLY LOWER DEW POINTS.
AS FOR SHOWERS AND STORMS...THE CENTER OF THE UPPER HIGH WILL BE
NEAR KANSAS CITY TODAY AND IT WILL SLOWLY SINK SOUTH THROUGH WED.
IT/S INFLUENCES WILL SLOWLY LOSE ITS GRIP ON THE GREAT LAKES...AND
THE RING OF CONVECTION AROUND THIS RIDGE SHOULD GRADUALLY EASE INTO
THE CWA THROUGH THE SHORT TERM. AT THE SURFACE THE MODELS ARE IN
GOOD AGREEMENT PUSHING A COLD FRONT THROUGH HERE TUESDAY NIGHT.
THE BEST JET DYNAMICS STAYS TO OUR NORTH AND WEST TODAY AND TONIGHT.
SO FEEL ANY SHOWERS AND STORMS THAT REACHES THE GRR CWA WILL BE IN A
WEAKENING STATE AS THEY RUN AWAY FROM THE BEST DYNAMICS AND INTO THE
RIDGE. HOWEVER A LOW LEVEL JET IS POISED TO PUSH IN AHEAD OF THE
COLD FRONT BY TUESDAY AFTERNOON INTO THE EVENING. THIS APPEARS TO
BE THE BEST CHANCE FOR PCPN AND HAVE RAISED POPS TO LIKELY ACROSS
MUCH OF THE CWA. SEVERE STORMS WILL BE POSSIBLE FROM ROUGHLY MID
AFTERNOON THROUGH ABOUT MIDNIGHT. DAMAGING WIND WILL BE THE MAIN
THREAT WILL SOME LARGE HAIL POSSIBLE.
THE FRONT SHOULD BE THROUGH THE CWA BY WED MORNING AND HAVE
MAINTAINED A DRY FORECAST. NOT MUCH COOLER BEHIND THE FRONT...WITH
HEAT INDEX READINGS ONLY RETREATING TO AROUND 90.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 344 AM EDT MON AUG 26 2013
MODELS ARE CONSISTENT IN SHOWING THE PLAINS RIDGE HANGING ON THROUGH
THE LONG TERM WITH NORTHWEST FLOW IN PLACE OVER THE GREAT LAKES.
500MB HEIGHTS WILL BE HIGH ENOUGH (580S DM/S) AND 850MB TEMPS WARM
ENOUGH (+16C TO +20C) THAT HIGH TEMPS WILL REMAIN IN THE MIDDLE 80S
TO AROUND 90.
MAIN ISSUE WILL BE TRYING TO TIME ANY PRECIPITATION INTO THE AREA AS
SHORTWAVE ENERGY SLIDES SOUTHEAST IN THE NORTHWEST UPPER FLOW.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT LOOK DRY WITH HIGH PRESSURE
IN PLACE BEHIND WEDNESDAY/S FROPA. FRIDAY AND FRIDAY NIGHT...BOTH
THE GFS AND THE ECMWF ARE INSISTENT THAT A WARM FRONT WILL BE NEARBY
WITH PRECIPITATION IN THE AREA. NOT CONFIDENT IN THIS SCENARIO...SO
ONLY HAVE 20 PCT POPS IN THE FORECAST. KEPT THE FORECAST DRY
SATURDAY AND SATURDAY NIGHT WITH ANOTHER 20 PCT CHANCE FOR SHOWERS
AND STORMS ON SUNDAY. THE ECMWF AND GFS DIVERGE ON SURFACE FEATURES
FOR NEXT SUNDAY. OPTED TO FOLLOW THE GFS HERE AND HAVE A SMALL
CHANCE IN THE FORECAST AS ANOTHER WARM FRONT IS PROGD IN THE AREA.
OVERALL..THE LONG TERM PERIOD LOOKS TO REMAIN WARM WITH ABOVE NORMAL
TEMPERATURES. PRECIPITATION CHANCES ARE A TOUGH CALL...BUT IT
APPEARS SMALL CHANCES FOR SHOWERS AND STORMS EXIST BOTH FRIDAY AND
SUNDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 720 AM EDT MON AUG 26 2013
VFR WEATHER IS EXPECTED THIS MORNING...WITH AN INCREASING
SOUTHWEST WIND. BY LATE MORNING...SOUTHWEST WINDS OF 10-20 KNOTS
SHOULD BE COMMON. MID AND HIGH CLOUDS WILL CONTINUE TO DRIFT IN
FROM THE NORTH...BASES SHOULD BE ABOVE 12000FT.
STORMS TO THE NORTH THIS MORNING MAY EVENTUALLY MAKE THERE WAY
INTO THE NORTHERN TAF SITES THIS AFTERNOON. CONFIDENCE IN THIS
OCCURRING IS NOT HIGH THOUGH AND ONLY INCLUDED VICINITY THUNDER
WORDING FOR THIS AFTERNOON.
CEILINGS OF 5000-10000FT ARE EXPECTED TONIGHT WITH THE POTENTIAL
OF ADDITIONAL STORMS ROLLING IN LATE. STORMS WILL MOVE ACROSS
MINNESOTA AND WISCONSIN THIS EVENING AND MAY PUSH INTO THE TAF
SITES LATE TONIGHT. CONFIDENCE IN THE EVOLUTION REMAINS LOW AND
GIVEN ITS THEN END OF THE FORECAST PERIOD DID NOT INCLUDE THUNDER
FOR LATE TONIGHT YET.
&&
.MARINE...
ISSUED AT 344 AM EDT MON AUG 26 2013
SOUTHWEST FLOW WILL CONTINUE TO BRING SCA CONDITIONS TODAY. HOWEVER
AS THE FRONT APPROACHES WINDS WILL SLOWLY WEAKEN. FEEL CONDITIONS
WILL IMPROVE TOWARD EVENING...AND AS SUCH...MOVED UP THE ENDING OF
THE SCA.
ANOTHER PERIOD OF HIGHER WINDS AND WAVES WILL OCCUR BEHIND THE FRONT
FOR LATE TUESDAY NIGHT INTO WEDNESDAY WHEN ANOTHER SCA MAY BE NEEDED
WITH A NORTHERLY FLOW.
&&
.HYDROLOGY...
ISSUED AT 344 AM EDT MON AUG 26 2013
MOST AREAS SHOULD SEE BETWEEN A HALF INCH AND ONE INCH OF RAIN
THROUGH TUESDAY NIGHT. THE HIGHEST TOTALS SHOULD BE ACROSS THE
NORTHERN CWA. THIS HAS BEEN THE DRIER AREA...A SHOULD BE ABLE TO
HANDLE THIS AMOUNT OF RAIN. LOCALIZED POOR DRAINAGE FLOODING WILL BE
POSSIBLE IN PERSISTENT STORMS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 6 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...DUKE
AVIATION...DUKE
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1145 AM CDT MON AUG 26 2013
.UPDATED...
ISSUED AT 1145 AM CDT MON AUG 26 2013
RAINFALL UP TO 3 INCHES FELL ACROSS PARTS OF TAYLOR COUNTY THIS
MORNING. WITH THE SFC BOUNDARY WAVERING ACROSS THE AREA THROUGH THE
AFTERNOON/NIGHT. SOME STORMS COULD FIRE ALONG THIS BOUNDARY...JUST
NORTH OF THE LOW LEVEL CAPPING INVERSION...LATER THIS AFTERNOON.
THEN TONIGHT...A THUNDERSTORM COMPLEX IS EXPECTED TO ROLL
EAST/SOUTHEAST FORM THE NORTHERN PLAINS TO ACROSS NORTHERN WI. WITH
WARM CLOUD DEPTHS AROUND 4000 M AND PWS UPWARDS OF 200 PERCENT...ANY
STORM WILL BE CAPABLE OF HEAVY DOWNPOURS. TRAINING STORMS ARE
LIKELY. WITH THIS IN MIND...WILL ISSUE A FLASH FLOOD WATCH FOR
TAYLOR COUNTRY TONIGHT. STILL SOME UNCERTAINTY WITH THE EXACT
TRACK OF THIS MCS TONIGHT...IT COULD GO NORTH OF THE AREA. BUT
ENOUGH OF A THREAT WHERE A WATCH IS WARRANTED.
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 309 AM CDT MON AUG 26 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER
THE PACIFIC NORTHWEST AND EASTERN PACIFIC...AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUES TO STREAM OUT OF BAJA CALIFORNIA...UP THROUGH THE DAKOTAS
AND INTO THE NORTHERN GREAT LAKES AROUND THE SUBTROPICAL RIDGE. ONE
SUCH SHORTWAVE COMBINED WITH 700MB MOISTURE TRANSPORT SUPPORTING
CONVECTION TRACKING ACROSS FAR NORTHERN WI AND UPPER MICHIGAN.
REGARDING MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED
VALUES OF 1.5-2 INCHES FROM EASTERN SOUTH DAKOTA INTO THE NORTHERN
GREAT LAKES. AIRMASS IS ALSO VERY WARM WITH 850MB TEMPS FROM 00Z
RAOBS OF 22-24C ACROSS THE FORECAST AREA AND 24-28C OVER THE
NORTHERN PLAINS. WITH THE FORECAST AREA IN THE WARM SECTOR...SOUTH
OF A WARM FRONT POSITIONED OVER FAR NORTHERN WI...A SOUTHERLY BREEZE
HAS ONLY ALLOWED TEMPS TO FALL INTO THE MID TO UPPER 70S. THIS SAME
SOUTHERLY BREEZE HAS ADVECTED IN SOME LOWER DEWPOINTS...WHICH HAVE
FALLEN INTO THE 60S...LOWEST IN THE SOUTHEAST HALF OF THE AREA. 00Z
DVN SOUNDING REALLY SHOWED THE DRIER AIR COMPARED TO MPX.
..MODEL VERIFICATION..
HAVE INCLUDED THIS SECTION AS IT HAS HIGH IMPORTANCE WITH THE
FORECAST OF HIGH TEMPERATURES AND CONVECTION. LOOKING AT 00Z RAOBS
FOR 925MB TEMPS AND COMPARING TO 25.00Z MODEL GUIDANCE...THE ECMWF
WAS THE BEST WITH ALMOST NO ERROR ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST. THE GFS WAS GENERALLY 1-2C TOO HIGH. LASTLY...THE
NAM/RAP WERE THE WORST...HAVING ERRORS ON THE ORDER OF 3-6C...
HIGHEST AT MSP. BECAUSE THE NAM/RAP WERE TOO HIGH...IT BROKE THE CAP
AND BROUGHT THE CONVECTION WAY TOO FAR SOUTH.
..HAZARDS..
1. HEAT. TEMPERATURES ARE LIKELY TO BE A FEW DEGREES HIGHER TODAY
AND WITH DEWPOINTS CLIMBING BACK INTO THE LOW 70S...HEAT INDICES
SHOULD TOP OUT IN THE 100-105 RANGE. THE HIGHEST HEAT INDICES LOOK
TO OCCUR FROM LAKE CITY DOWN TO LA CROSSE...AND HAVE UPGRADED THIS
AREA TO AN EXCESSIVE HEAT WARNING.
2. STORMS. SOME SEVERE POTENTIAL AFTER MIDNIGHT TONIGHT...MAINLY
ACROSS TAYLOR/CLARK COUNTIES. HAVE TO WATCH RAINFALL AMOUNTS TOO.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE SUGGESTS THE SUBTROPICAL RIDGING RETROGRADES
JUST SLIGHTLY WESTWARD DURING THE NEXT 24 HOURS. THE MAIN FEATURE OF
FOCUS IS A STRETCHED OUT SHORTWAVE IN THE MONSOONAL FLOW...LOCATED
FROM EASTERN UTAH INTO SOUTH CENTRAL WYOMING. MODELS BRING THIS
SHORTWAVE INTO THE DAKOTAS BY 00Z AND PERHAPS AS FAR EAST AS WESTERN
UPPER MI BY 12Z. THIS SHORTWAVE HELPS TO LIFT A SURFACE LOW SITTING
NEAR THE BLACK HILLS OF SOUTH DAKOTA TO NEAR MINNEAPOLIS BY 12Z TUE.
..DETAILS..
FOCUS FOR POTENTIAL CONVECTION TODAY WILL LIE ON THE LOCATION OF THE
WARM FRONT IN NORTHERN WI. FIRST OFF...THE CURRENT CONVECTION
CROSSING FAR NORTHERN WI AND UPPER MI COULD DROP INTO TAYLOR AND
POSSIBLY CLARK COUNTY BEFORE WEAKENING THIS MORNING. THE OUTFLOW
FROM THE CONVECTION SHOULD HELP PUSH THE FRONT SOUTH TOWARDS I-94
THIS AFTERNOON. THEN...THE NEXT QUESTION IS IF THE AIRMASS IS
CAPPED...WHICH ENTIRELY DEPENDS ON HOW WARM WE GET. THERE SHOULD BE
PLENTY OF SUN TODAY ACROSS THE FORECAST AREA WITH MAYBE A FEW STRAY
CIRRUS CLOUDS. ECMWF 925MB TEMPS ARE PROGGED ABOUT 1-2C HIGHER
COMPARED TO YESTERDAY...THUS ANTICIPATING HIGHS TO BE ABOUT 1-3F
HIGHER... YIELDING READINGS MAINLY IN THE LOW TO MID 90S. A FEW
SPOTS LIKE LSE COULD EVEN HIT THE UPPER 90S. ECMWF ALSO DID VERY
WELL WITH THE DEWPOINTS YESTERDAY AND SUGGESTS THEY SHOULD CLIMB
INTO THE LOW 70S IN THE AFTERNOON...DUE TO EVAPOTRANSPORATION AND
THE HIGHER MOISTURE TO OUR NORTHWEST SLIDING SOUTH. THE FORECAST
HIGHS AND DEWPOINTS WOULD SEEM TO POINT TO POTENTIAL FOR THE CAP TO
BREAK...THUS HAVE INCLUDED 20-40 PERCENT CHANCES ON THE WARM FRONT
FOR THE AFTERNOON. SHOULD STORMS DEVELOP...0-6KM SHEAR IS ONLY 25 KT
AT BEST WITH 0-3KM NEAR 20KT. THIS MEANS THE STORMS WILL PROBABLY BE
UNORGANIZED AND MOST LIKELY JUST HEAVY RAIN MAKERS GIVEN HIGH CAPE
AND NEAR 2 INCH PRECIPITABLE WATERS.
TONIGHT IS A BIT MORE INTERESTING. A CONVECTIVE COMPLEX APPEARS
LIKELY TO DEVELOP IN THE GRAND FORKS AREA IN THE EVENING AHEAD OF
THE SHORTWAVE. THIS CONVECTION...AIDED ALSO BY 700MB MOISTURE
TRANSPORT LIKE THE CONVECTION GOING OVER UPPER MI...SHOULD TRACK
EAST-SOUTHEAST INTO NORTHERN WI. THIS MEANS TAYLOR/CLARK COULD BE
IMPACTED BY THE COMPLEX AFTER MIDNIGHT. ADDITIONAL CONVECTION COULD
FORM ON THE NOSE OF 850MB MOISTURE TRANSPORT NORTH OF I-94 THIS
EVENING AS WELL. CANNOT RULE OUT SOME SEVERE WEATHER...LIKELY IN THE
FORM OF DAMAGING WINDS AND LARGE HAIL...ESPECIALLY AFTER MIDNIGHT
WHEN 0-6 KM SHEAR VALUES APPROACH 30-40 KT. THE REST OF THE AREA
SHOULD STAY MAINLY DRY...CAPPED AND WARM WITH A SOUTHERLY BREEZE
PERSISTING. LOW TEMPERATURES ARE LIKELY TO BE SIMILAR TO NOW GIVEN
SIMILAR CONDITIONS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 309 AM CDT MON AUG 26 2013
..HAZARDS..
1. HEAT...WHICH WILL PERSIST INTO TUESDAY. COLD FRONT COMES THROUGH
TUESDAY NIGHT WHICH SHOULD HELP ADVECT BOTH SOMEWHAT COOLER AND MORE
IMPORTANTLY DRIER AIR INTO THE AREA FOR WEDNESDAY. HEAT LOOKS TO
RETURN DURING LABOR DAY WEEKEND.
2. STORMS. THOSE ON TUESDAY COULD POSE A SEVERE AND HEAVY RAIN
THREAT NORTH OF I-94.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE CONTINUES TO SUGGEST THAT THE SUBTROPICAL HIGH
WILL RETROGRADE WESTWARD THROUGH THE WEEK...ENDING UP IN COLORADO ON
FRIDAY. THIS RETROGRESSION IS IN RESPONSE TO A SERIES OF SHORTWAVE
TROUGHS DROPPING INTO THE MID-ATLANTIC REGION ON THE EAST SIDE OF
THE RIDGE. AS WE HEAD INTO THE WEEKEND...THE SUBTROPICAL RIDGE WILL
SHIFT EAST IN RESPONSE TO WHAT LOOKS TO BE A VERY DEEP TROUGH FOR
THIS TIME OF YEAR COMING INTO THE PACIFIC NORTHWEST. IT SHOULD BE
NOTED THAT THE 26.00Z ECMWF THROWS A MAJOR CURVE BALL TO THE WEEKEND
PLAN...DEVIATING GREATLY FROM ITS PREVIOUS RUN IN SHOWING A TROUGH
DIGGING INTO THE WESTERN GREAT LAKES LATE SUNDAY. THE REASON IS
RELATED TO THIS TROUGH BEING STRONGER AND TRACKING FARTHER SOUTH
COMING OUT OF SOUTHWEST CANADA ON FRIDAY...COMPARED TO ITS PREVIOUS
RUN...THE 26.00Z GFS AND CANADIAN. NOT READY TO FULLY BUY INTO THE
26.00Z ECMWF QUITE YET BEFORE SEEING THE ECMWF ENSEMBLES AND ITS
NEXT RUN.
..DETAILS..
THE SURFACE OVER CENTRAL MN AT 12Z TUESDAY WILL GRADUALLY DROP
SOUTHEAST THROUGH TUESDAY AND TUESDAY NIGHT...IN RESPONSE TO THE
SHORTWAVE AND CONVECTION OVER NORTHERN WI/UPPER MI DROPPING
SOUTHEAST. HAVE KEPT SOME CHANCES ON TUESDAY NORTHEAST OF I-94 FOR
THE CONVECTION DROPPING SOUTHEAST...WHICH COULD BE SEVERE AS WELL.
THE REST OF THE AREA LOOKS CAPPED. TALKING ABOUT THE CAPPING...925MB
TEMPS ARE PROGGED TO REACH ABOUT 28C ON I-94 TO 30C IN NORTHEAST
IOWA. THESE READINGS SHOULD YIELD HIGHS RANGING FROM THE LOW TO
UPPER 90S...WARMEST IN RIVER VALLEYS. THE EXCESSIVE HEAT WARNING MAY
NEED EXPANSION INTO SOME OF NORTHEAST IOWA AND FAR SOUTHWEST WI IF
TEMP/DEWPOINT TRENDS CONTINUE. ALL CONVECTION LOOKS LIKE IT WILL BE
SOUTHEAST OF THE AREA FOR TUESDAY NIGHT...THUS WENT DRY THEN.
DRY CONDITIONS ARE EXPECTED FOR WEDNESDAY AND WEDNESDAY NIGHT AS
HIGH PRESSURE BUILDS OVER WISCONSIN AND MICHIGAN IN THE WAKE OF
TUESDAYS LOW AND COLD FRONTAL PASSAGE. 925MB TEMPS OF 24-26C STILL
SUPPORTS HIGHS IN THE MID 80S TO LOW 90S...THOUGH. DEWPOINTS MAY
STILL BE UP IN THE LOW 70S OVER NORTHEAST IOWA...BUT HEAT INDICES
ARE MORE AROUND 95 VERSUS THE 100-105 AS OF LATE.
THURSDAY THROUGH SATURDAY FEATURE A GRADUAL WARM ADVECTION
PATTERN...WHICH MEANS A RETURN FOR SOME CHANCES OF SHOWERS AND
THUNDERSTORMS. HIGHEST CHANCES ARE FORECAST THURSDAY NIGHT OVER
WISCONSIN WHERE THERE APPEARS TO BE A JUXTAPOSITION OF RIGHT
ENTRANCE REGION FORCING...A POSSIBLE SHORTWAVE MOVING THROUGH...AND
THE LOW LEVEL MOISTURE TRANSPORT. SOME OF THESE CHANCES OF SHOWERS
AND THUNDERSTORMS MAY BE ABLE TO BE BETTER REFINED...IN TERMS OF
DRYING SOME OUT...OVER THE COMING DAYS AS MODELS SETTLE INTO THE
TIMING OF THE WARM ADVECTION. ONCE THE WARM AIR COMES IN...WE WILL
HAVE TO BE CONCERNED WITH HEAT ADVISORIES...AS EVEN THE NEW 26.00Z
ECMWF SHOWS 925MB TEMPS APPROACHING 30C OVER WESTERN PORTIONS OF THE
FORECAST AREA LATE FRIDAY.
SUNDAY AND THE REST OF LABOR DAY WEEKEND FORECAST IS NOW UP IN THE
AIR DUE TO THE NEW 26.00Z ECMWF. PREVIOUSLY AND IN AGREEMENT WITH
THE 26.00Z GFS IT APPEARED MUCH OF THE AREA WOULD BE IN THE WARM
SECTOR...WITH 925MB TEMPS OF 29-32C WHICH COULD ALLOW FOR HIGHS
AROUND 100. IF THE NEW ECMWF IS RIGHT...WE GET A MOSTLY DRY COLD
FRONTAL PASSAGE ON SUNDAY WITH HIGHS MORE IN THE MID TO UPPER 80S.
MONDAY ENDS UP MUCH MUCH COOLER WITH HIGHS MOSTLY IN THE 60S.
COMPARE THIS TO ITS PREVIOUS 4 RUNS SHOWING 94-98 AT LA CROSSE FOR
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 640 AM CDT MON AUG 26 2013
EXPECT THE LOW LEVEL WIND SHEAR AT KLSE TO RAPIDLY DISSIPATE BY
26.14Z AS THE LOW LEVEL JET AND PRESSURE GRADIENT WEAKENS...AND
THE NOCTURNAL INVERSION DISSIPATES THROUGH DIURNAL MIXING.
FOR TODAY...EXPECT ONLY SCATTERED 15K FOOT CLOUDS. WINDS WILL GUST
FROM SOUTHWEST INTO THE 15 TO 25 KNOT RANGE.
AFTER 27.07Z...THERE IS CONCERN THAT LOW LEVEL WIND SHEAR WILL
DEVELOP AT KLSE AS THE WINDS DROP TO LESS THAN 10 KNOTS BELOW THE
NOCTURNAL INVERSION AND THE LOW LEVEL JET STRENGTHENS ALOFT. THE
GFS HAS THIS JET CLIMBING INTO THE 30 TO 35 KNOT RANGE. MEANWHILE
THE NAM/WRF HAS THIS JET STRENGTHENING INTO THE 40 TO 45 KNOT
RANGE. DUE TO THE UNCERTAINTY OF THE STRENGTH OF THIS JET...HELD
OFF MENTIONING IT.
&&
.CLIMATE...
ISSUED AT 346 PM CDT SUN AUG 25 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
034-042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ032-033-041.
FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH TUESDAY
MORNING FOR WIZ017.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ086-087-
094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-088-096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
UPDATE.......RIECK
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....BOYNE
CLIMATE......WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
640 AM CDT MON AUG 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 309 AM CDT MON AUG 26 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER
THE PACIFIC NORTHWEST AND EASTERN PACIFIC...AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUES TO STREAM OUT OF BAJA CALIFORNIA...UP THROUGH THE DAKOTAS
AND INTO THE NORTHERN GREAT LAKES AROUND THE SUBTROPICAL RIDGE. ONE
SUCH SHORTWAVE COMBINED WITH 700MB MOISTURE TRANSPORT SUPPORTING
CONVECTION TRACKING ACROSS FAR NORTHERN WI AND UPPER MICHIGAN.
REGARDING MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED
VALUES OF 1.5-2 INCHES FROM EASTERN SOUTH DAKOTA INTO THE NORTHERN
GREAT LAKES. AIRMASS IS ALSO VERY WARM WITH 850MB TEMPS FROM 00Z
RAOBS OF 22-24C ACROSS THE FORECAST AREA AND 24-28C OVER THE
NORTHERN PLAINS. WITH THE FORECAST AREA IN THE WARM SECTOR...SOUTH
OF A WARM FRONT POSITIONED OVER FAR NORTHERN WI...A SOUTHERLY BREEZE
HAS ONLY ALLOWED TEMPS TO FALL INTO THE MID TO UPPER 70S. THIS SAME
SOUTHERLY BREEZE HAS ADVECTED IN SOME LOWER DEWPOINTS...WHICH HAVE
FALLEN INTO THE 60S...LOWEST IN THE SOUTHEAST HALF OF THE AREA. 00Z
DVN SOUNDING REALLY SHOWED THE DRIER AIR COMPARED TO MPX.
..MODEL VERIFICATION..
HAVE INCLUDED THIS SECTION AS IT HAS HIGH IMPORTANCE WITH THE
FORECAST OF HIGH TEMPERATURES AND CONVECTION. LOOKING AT 00Z RAOBS
FOR 925MB TEMPS AND COMPARING TO 25.00Z MODEL GUIDANCE...THE ECMWF
WAS THE BEST WITH ALMOST NO ERROR ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST. THE GFS WAS GENERALLY 1-2C TOO HIGH. LASTLY...THE
NAM/RAP WERE THE WORST...HAVING ERRORS ON THE ORDER OF 3-6C...
HIGHEST AT MSP. BECAUSE THE NAM/RAP WERE TOO HIGH...IT BROKE THE CAP
AND BROUGHT THE CONVECTION WAY TOO FAR SOUTH.
..HAZARDS..
1. HEAT. TEMPERATURES ARE LIKELY TO BE A FEW DEGREES HIGHER TODAY
AND WITH DEWPOINTS CLIMBING BACK INTO THE LOW 70S...HEAT INDICES
SHOULD TOP OUT IN THE 100-105 RANGE. THE HIGHEST HEAT INDICES LOOK
TO OCCUR FROM LAKE CITY DOWN TO LA CROSSE...AND HAVE UPGRADED THIS
AREA TO AN EXCESSIVE HEAT WARNING.
2. STORMS. SOME SEVERE POTENTIAL AFTER MIDNIGHT TONIGHT...MAINLY
ACROSS TAYLOR/CLARK COUNTIES. HAVE TO WATCH RAINFALL AMOUNTS TOO.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE SUGGESTS THE SUBTROPICAL RIDGING RETROGRADES
JUST SLIGHTLY WESTWARD DURING THE NEXT 24 HOURS. THE MAIN FEATURE OF
FOCUS IS A STRETCHED OUT SHORTWAVE IN THE MONSOONAL FLOW...LOCATED
FROM EASTERN UTAH INTO SOUTH CENTRAL WYOMING. MODELS BRING THIS
SHORTWAVE INTO THE DAKOTAS BY 00Z AND PERHAPS AS FAR EAST AS WESTERN
UPPER MI BY 12Z. THIS SHORTWAVE HELPS TO LIFT A SURFACE LOW SITTING
NEAR THE BLACK HILLS OF SOUTH DAKOTA TO NEAR MINNEAPOLIS BY 12Z TUE.
..DETAILS..
FOCUS FOR POTENTIAL CONVECTION TODAY WILL LIE ON THE LOCATION OF THE
WARM FRONT IN NORTHERN WI. FIRST OFF...THE CURRENT CONVECTION
CROSSING FAR NORTHERN WI AND UPPER MI COULD DROP INTO TAYLOR AND
POSSIBLY CLARK COUNTY BEFORE WEAKENING THIS MORNING. THE OUTFLOW
FROM THE CONVECTION SHOULD HELP PUSH THE FRONT SOUTH TOWARDS I-94
THIS AFTERNOON. THEN...THE NEXT QUESTION IS IF THE AIRMASS IS
CAPPED...WHICH ENTIRELY DEPENDS ON HOW WARM WE GET. THERE SHOULD BE
PLENTY OF SUN TODAY ACROSS THE FORECAST AREA WITH MAYBE A FEW STRAY
CIRRUS CLOUDS. ECMWF 925MB TEMPS ARE PROGGED ABOUT 1-2C HIGHER
COMPARED TO YESTERDAY...THUS ANTICIPATING HIGHS TO BE ABOUT 1-3F
HIGHER... YIELDING READINGS MAINLY IN THE LOW TO MID 90S. A FEW
SPOTS LIKE LSE COULD EVEN HIT THE UPPER 90S. ECMWF ALSO DID VERY
WELL WITH THE DEWPOINTS YESTERDAY AND SUGGESTS THEY SHOULD CLIMB
INTO THE LOW 70S IN THE AFTERNOON...DUE TO EVAPOTRANSPORATION AND
THE HIGHER MOISTURE TO OUR NORTHWEST SLIDING SOUTH. THE FORECAST
HIGHS AND DEWPOINTS WOULD SEEM TO POINT TO POTENTIAL FOR THE CAP TO
BREAK...THUS HAVE INCLUDED 20-40 PERCENT CHANCES ON THE WARM FRONT
FOR THE AFTERNOON. SHOULD STORMS DEVELOP...0-6KM SHEAR IS ONLY 25 KT
AT BEST WITH 0-3KM NEAR 20KT. THIS MEANS THE STORMS WILL PROBABLY BE
UNORGANIZED AND MOST LIKELY JUST HEAVY RAIN MAKERS GIVEN HIGH CAPE
AND NEAR 2 INCH PRECIPITABLE WATERS.
TONIGHT IS A BIT MORE INTERESTING. A CONVECTIVE COMPLEX APPEARS
LIKELY TO DEVELOP IN THE GRAND FORKS AREA IN THE EVENING AHEAD OF
THE SHORTWAVE. THIS CONVECTION...AIDED ALSO BY 700MB MOISTURE
TRANSPORT LIKE THE CONVECTION GOING OVER UPPER MI...SHOULD TRACK
EAST-SOUTHEAST INTO NORTHERN WI. THIS MEANS TAYLOR/CLARK COULD BE
IMPACTED BY THE COMPLEX AFTER MIDNIGHT. ADDITIONAL CONVECTION COULD
FORM ON THE NOSE OF 850MB MOISTURE TRANSPORT NORTH OF I-94 THIS
EVENING AS WELL. CANNOT RULE OUT SOME SEVERE WEATHER...LIKELY IN THE
FORM OF DAMAGING WINDS AND LARGE HAIL...ESPECIALLY AFTER MIDNIGHT
WHEN 0-6 KM SHEAR VALUES APPROACH 30-40 KT. THE REST OF THE AREA
SHOULD STAY MAINLY DRY...CAPPED AND WARM WITH A SOUTHERLY BREEZE
PERSISTING. LOW TEMPERATURES ARE LIKELY TO BE SIMILAR TO NOW GIVEN
SIMILAR CONDITIONS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 309 AM CDT MON AUG 26 2013
..HAZARDS..
1. HEAT...WHICH WILL PERSIST INTO TUESDAY. COLD FRONT COMES THROUGH
TUESDAY NIGHT WHICH SHOULD HELP ADVECT BOTH SOMEWHAT COOLER AND MORE
IMPORTANTLY DRIER AIR INTO THE AREA FOR WEDNESDAY. HEAT LOOKS TO
RETURN DURING LABOR DAY WEEKEND.
2. STORMS. THOSE ON TUESDAY COULD POSE A SEVERE AND HEAVY RAIN
THREAT NORTH OF I-94.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE CONTINUES TO SUGGEST THAT THE SUBTROPICAL HIGH
WILL RETROGRADE WESTWARD THROUGH THE WEEK...ENDING UP IN COLORADO ON
FRIDAY. THIS RETROGRESSION IS IN RESPONSE TO A SERIES OF SHORTWAVE
TROUGHS DROPPING INTO THE MID-ATLANTIC REGION ON THE EAST SIDE OF
THE RIDGE. AS WE HEAD INTO THE WEEKEND...THE SUBTROPICAL RIDGE WILL
SHIFT EAST IN RESPONSE TO WHAT LOOKS TO BE A VERY DEEP TROUGH FOR
THIS TIME OF YEAR COMING INTO THE PACIFIC NORTHWEST. IT SHOULD BE
NOTED THAT THE 26.00Z ECMWF THROWS A MAJOR CURVE BALL TO THE WEEKEND
PLAN...DEVIATING GREATLY FROM ITS PREVIOUS RUN IN SHOWING A TROUGH
DIGGING INTO THE WESTERN GREAT LAKES LATE SUNDAY. THE REASON IS
RELATED TO THIS TROUGH BEING STRONGER AND TRACKING FARTHER SOUTH
COMING OUT OF SOUTHWEST CANADA ON FRIDAY...COMPARED TO ITS PREVIOUS
RUN...THE 26.00Z GFS AND CANADIAN. NOT READY TO FULLY BUY INTO THE
26.00Z ECMWF QUITE YET BEFORE SEEING THE ECMWF ENSEMBLES AND ITS
NEXT RUN.
..DETAILS..
THE SURFACE OVER CENTRAL MN AT 12Z TUESDAY WILL GRADUALLY DROP
SOUTHEAST THROUGH TUESDAY AND TUESDAY NIGHT...IN RESPONSE TO THE
SHORTWAVE AND CONVECTION OVER NORTHERN WI/UPPER MI DROPPING
SOUTHEAST. HAVE KEPT SOME CHANCES ON TUESDAY NORTHEAST OF I-94 FOR
THE CONVECTION DROPPING SOUTHEAST...WHICH COULD BE SEVERE AS WELL.
THE REST OF THE AREA LOOKS CAPPED. TALKING ABOUT THE CAPPING...925MB
TEMPS ARE PROGGED TO REACH ABOUT 28C ON I-94 TO 30C IN NORTHEAST
IOWA. THESE READINGS SHOULD YIELD HIGHS RANGING FROM THE LOW TO
UPPER 90S...WARMEST IN RIVER VALLEYS. THE EXCESSIVE HEAT WARNING MAY
NEED EXPANSION INTO SOME OF NORTHEAST IOWA AND FAR SOUTHWEST WI IF
TEMP/DEWPOINT TRENDS CONTINUE. ALL CONVECTION LOOKS LIKE IT WILL BE
SOUTHEAST OF THE AREA FOR TUESDAY NIGHT...THUS WENT DRY THEN.
DRY CONDITIONS ARE EXPECTED FOR WEDNESDAY AND WEDNESDAY NIGHT AS
HIGH PRESSURE BUILDS OVER WISCONSIN AND MICHIGAN IN THE WAKE OF
TUESDAYS LOW AND COLD FRONTAL PASSAGE. 925MB TEMPS OF 24-26C STILL
SUPPORTS HIGHS IN THE MID 80S TO LOW 90S...THOUGH. DEWPOINTS MAY
STILL BE UP IN THE LOW 70S OVER NORTHEAST IOWA...BUT HEAT INDICES
ARE MORE AROUND 95 VERSUS THE 100-105 AS OF LATE.
THURSDAY THROUGH SATURDAY FEATURE A GRADUAL WARM ADVECTION
PATTERN...WHICH MEANS A RETURN FOR SOME CHANCES OF SHOWERS AND
THUNDERSTORMS. HIGHEST CHANCES ARE FORECAST THURSDAY NIGHT OVER
WISCONSIN WHERE THERE APPEARS TO BE A JUXTAPOSITION OF RIGHT
ENTRANCE REGION FORCING...A POSSIBLE SHORTWAVE MOVING THROUGH...AND
THE LOW LEVEL MOISTURE TRANSPORT. SOME OF THESE CHANCES OF SHOWERS
AND THUNDERSTORMS MAY BE ABLE TO BE BETTER REFINED...IN TERMS OF
DRYING SOME OUT...OVER THE COMING DAYS AS MODELS SETTLE INTO THE
TIMING OF THE WARM ADVECTION. ONCE THE WARM AIR COMES IN...WE WILL
HAVE TO BE CONCERNED WITH HEAT ADVISORIES...AS EVEN THE NEW 26.00Z
ECMWF SHOWS 925MB TEMPS APPROACHING 30C OVER WESTERN PORTIONS OF THE
FORECAST AREA LATE FRIDAY.
SUNDAY AND THE REST OF LABOR DAY WEEKEND FORECAST IS NOW UP IN THE
AIR DUE TO THE NEW 26.00Z ECMWF. PREVIOUSLY AND IN AGREEMENT WITH
THE 26.00Z GFS IT APPEARED MUCH OF THE AREA WOULD BE IN THE WARM
SECTOR...WITH 925MB TEMPS OF 29-32C WHICH COULD ALLOW FOR HIGHS
AROUND 100. IF THE NEW ECMWF IS RIGHT...WE GET A MOSTLY DRY COLD
FRONTAL PASSAGE ON SUNDAY WITH HIGHS MORE IN THE MID TO UPPER 80S.
MONDAY ENDS UP MUCH MUCH COOLER WITH HIGHS MOSTLY IN THE 60S.
COMPARE THIS TO ITS PREVIOUS 4 RUNS SHOWING 94-98 AT LA CROSSE FOR
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 640 AM CDT MON AUG 26 2013
EXPECT THE LOW LEVEL WIND SHEAR AT KLSE TO RAPIDLY DISSIPATE BY
26.14Z AS THE LOW LEVEL JET AND PRESSURE GRADIENT WEAKENS...AND
THE NOCTURNAL INVERSION DISSIPATES THROUGH DIURNAL MIXING.
FOR TODAY...EXPECT ONLY SCATTERED 15K FOOT CLOUDS. WINDS WILL GUST
FROM SOUTHWEST INTO THE 15 TO 25 KNOT RANGE.
AFTER 27.07Z...THERE IS CONCERN THAT LOW LEVEL WIND SHEAR WILL
DEVELOP AT KLSE AS THE WINDS DROP TO LESS THAN 10 KNOTS BELOW THE
NOCTURNAL INVERSION AND THE LOW LEVEL JET STRENGTHENS ALOFT. THE
GFS HAS THIS JET CLIMBING INTO THE 30 TO 35 KNOT RANGE. MEANWHILE
THE NAM/WRF HAS THIS JET STRENGTHENING INTO THE 40 TO 45 KNOT
RANGE. DUE TO THE UNCERTAINTY OF THE STRENGTH OF THIS JET...HELD
OFF MENTIONING IT.
&&
.CLIMATE...
ISSUED AT 346 PM CDT SUN AUG 25 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
034-042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ032-033-041.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ086-087-
094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-088-096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
CLIMATE...WETENKAMP
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
432 PM EDT MON AUG 26 2013
.SHORT TERM (TONIGHT THROUGH WEDNESDAY)...AS DISCUSSED THIS
MORNING...AN AREA OF Q-VECTOR DIVERGENCE AND SUBSIDENCE HAS NOT
ELIMINATED AFTN CONVECTION...BUT THUS FAR SEEMS TO BE LIMITING
UPDRAFT STRENGTH AND OVERALL STRENGTH/COVERAGE OF THE STORMS. THAT
SAID...THERE ARE SCT SHRA AND TSTMS MVG WSW AT NEAR 20 KTS ACROSS
CEN FL AND GIVEN THIS MOTION IT HAS NOT TAKEN MUCH TO PROVIDE SOME
GUSTS TO 35 KTS IN A FEW. IN ADDITION...A WEST COAST SEA BREEZE HAS
FORMED AND MOVED SLIGHTLY INLAND AND THIS MAY HELP INVIGORATED
STORMS AS THEY MOVE ACROSS THE BOUNDARY AND INTO THE WATERS. WILL
CONTINUE TO SHOW SCT POPS FOR REMAINDER OF THE AFTN AND EVENING
FOCUSING ALONG THE COAST AND THEN OFFSHORE (SRN 2/3RDS) FOR BEST
CHCS. COULD SEE SOME GUSTY WINDS WITH THESE FOR MARINE AREAS...ESP
FROM TAMPA BAY SOUTH WHERE HRRR SHOWS THE BEST FLARE UP IN
CONVECTION LATE.
AREA OF WEAK LARGE SCALE SUBSIDENCE SEEN IN Q-VECTORS TODAY MOVES
SOUTH OUT OF THE REGION FOR TUE LEAVING A MORE NEUTRAL REGIME IN
PLACE. OVERALL MOISTURE/PWS ARE FORECAST TO DECREASE
SLIGHTLY AS MODEST DRYING CONTINUES FROM THE ENE AROUND SFC HIGH
CENTERED TO THE NORTH...BUT WHAT MOISTURE IS PRESENT REMAINS ALL PACKED
IN LOWEST LAYERS. GIVEN THIS...THINK MOS POPS ARE ON LOW SIDE AND
LEANED A BIT MORE TOWARD CLIMO WIND REGIME POPS WHICH SUGGEST
30-40% CHCS FAVORING COASTAL COS ON TUE. IN FACT W/O
SUBSIDENCE...MAY SEE SOME BETTER UPDRAFTS THAN WE HAVE TODAY. BY
WED MOISTURE CONTENT IS AT LOWEST POINT AND POPS ARE CONFINED TO
20-30 PERCENT FOR ALL BE FMY AREA WHERE POPS ARE CLOSER TO 40%. SO
OVERALL WILL SEE NOTICEABLY LOWER COVERAGE OF STORMS THAN LAST WEEK
ALTHOUGH NOT COMPLETELY DRY.
&&
.LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...
LONG TERM PERIOD BEGINS WITH A SURFACE RIDGE OF HIGH PRESSURE
SITTING ACROSS NORTH FLORIDA AND THE GULF STATES...A 500 MB HIGH
PRESSURE AREA DOMINATES THE CENTRAL UNITED STATES. A STALLED FRONT
EAST AND SOUTH OF FLORIDA ALIGNS WITH AN AMPLIFYING 500 MB TROUGH
OVER THE EASTERN UNITED STATES HEADING INTO NEXT WEEKEND.
INTERESTINGLY...THE 00Z GFS HAS THE TROUGH BRIEFLY FORMING A
CUTOFF LOW AS BOTH THE SURFACE RIDGE AND THE 500 MB DOME OF HIGH
PRESSURE BEGIN TO ERODE. THIS COULD OPEN THE DOOR TO HIGHER RAIN
CHANCES LATE WEEK INTO THE WEEKEND.
HIGH PRESSURE BEGINS TO BUILD BACK IN BY THE END OF THE LONG
TERM FORECAST PERIOD ON MONDAY...AS THE 500 MB TROUGH BACKS NORTH.
EXPECT TEMPERATURES TO STAY NEAR CLIMATOLOGICAL NORMALS IN THE
EXTENDED PERIOD...THOUGH POPS COULD BE AFFECTED BY THE TROUGH
AMPLIFYING OVER THE EASTERN US. SEA BREEZE CONVECTION WILL BE A
LARGE DRIVER OF POPS...THOUGH THE SYNOPTIC INFLUENCES COULD RAISE
RAIN CHANCES ABOVE NORMAL.
&&
.AVIATION...
PREVAILING VFR WITH VCNTY TSRA DURING A 20Z-03Z WINDOW ALTHOUGH
PGD/FMY/RSW COULD SEE A TSRA AT THE FIELD. EASTERLY WINDS DIMINISH
LATER TONIGHT AND BACK TO NE WITH SOME LOW STRATUS POSSIBLE BUT WILL
KEEP TAFS AT SCT010-020.
&&
.FIRE WEATHER...NO CONCERNS.
&&
,MARINE...MAIN CONCERN IS WITH GUSTY WINDS ASSOC W/ OFFSHORE MOVG
TSTMS NEXT FEW DAYS. MAY SEE SUSTAINED WINDS NEAR SCEC LEVELS WITH
ERLY SURGE TONIGHT...BUT FOR NOW KEPT SPEEDS AROUND 15 KTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 74 89 76 91 / 30 40 20 30
FMY 74 92 74 92 / 20 40 20 40
GIF 72 91 72 92 / 10 30 10 30
SRQ 74 90 73 89 / 30 40 20 30
BKV 69 91 69 92 / 10 40 20 20
SPG 77 89 77 90 / 30 40 20 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...88/GITTINGER
LONG TERM/AVIATION...09/RUDE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1043 AM MDT MON AUG 26 2013
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 243 AM MDT MON AUG 26 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW LARGE H5 598DM RIDGE
STILL IN PLACE ACROSS THE CENTRAL CONUS. WHILE THERE IS WEAK
ENERGY ROTATING AROUND THE WEST SIDE OF THE RIDGE THAT CONTINUES TO
INITIATE SHOWER/THUNDERSTORM ACTIVITY OVER THE MOUNTAINS...BEYOND
HIGH CLOUDS MOVING ACROSS THE WESTERN PART OF OUR CWA THESE WEAK
WAVES WILL NOT HAVE ANY INFLUENCE ON OUR WEATHER LOCALLY. WITH
THIS VERY STAGNANT PATTERN IN PLACE FORECAST FOCUS CONTINUES TO
BE ON HOT TEMPERATURES AND MARGINAL FIRE WEATHER CONDITIONS.
TIGHT GRADIENT IS STILL IN PLACE ACROSS OUR CWA ON EASTER EDGE OF
TEE TROUGH...HOWEVER THE MAIN TROUGH AXIS IS BEGINNING OT SHIFT
CLOSER TO THE KS/CO BORDER WHICH SHOULD HELP RELAX THE GRADIENT
ACROSS THE NW HALF OF OUR CWA. AS WOULD BE EXPECTED WITH LESS
GRADIENT IN THE NW PART OF OUR CWA...SHORT RANGE MODELS ARE
BACKING OFF ON WINDS ACROSS THE WEST...WITH GUSTY WINDS MAINLY
ACROSS OUR EASTERN CWA. LOWEST RH VALUES SHOULD BE ACROSS THE WEST
AS HAS BEEN THE CASE THE LAST FEW DAYS...AND ARE ALREADY MARGINAL
FOR RFW. THE CHANCE FOR RH/WIND CROSSOVER IS VERY LOW...SO FIRE
WEATHER HIGHLIGHT WILL NOT BE NECESSARY.
REGARDING TEMPERATURES...NAM/GFS/ECMWF ALL SHOW VERY SIMILAR
AIR MASS IN PLACE THROUGH TUESDAY WHICH MEAN THERE SHOULDNT BE A
LOT OF VARIANCE FROM UPPER 90S/LOW 100S. BETTER MIXING COULD
RESULT IN NEAR RECORD HIGHS AT A FEW LOCATIONS. I DECIDED TO KEEP
ONGOING FORECAST WITHIN A DEGREE OR TWO OF PERSISTENCE WITH LITTLE
EXPECTED TO CHANGE. THROUGH TUESDAY NIGHT. BY WEDNESDAY A
SHORTWAVE TROUGH/MID LEVEL VORTICITY MAX WILL ROTATE FROM THE
SOUTHERN PLAINS AND ACROSS WESTERN KANSAS OUT OF THE SOUTH. WHILE
LARGE SCALE ASCENT AND ELEVATED INSTABILITY ASSOCIATED WITH A
MID LEVEL COLD POOL WILL MOVE OVER THE CWA...THERE IS A
SIGNIFICANTLY DRY AIR MASS IN PLACE. BEYOND AN INCREASE IN CLOUDS I
AM NOT ANTICIPATING ANY PRECIP WITH THIS FEATURE. THIS WILL HELP
REDUCE TEMPS OVER THE CWA BY ABOUT 5-7F FOR MOST LOCATIONS...WHICH
IS A SMALL CONCESSION SINCE THIS IS STILL WELL ABOVE NORMAL.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 243 AM MDT MON AUG 26 2013
THE UPPER LEVEL RIDGE WILL PERSIST THROUGH THE EXTENDED PERIOD. THE
WARMEST 850 MB TEMPERATURES WILL BE ON FRIDAY AND SATURDAY RESULTING
IN HIGH TEMPERATURES IN THE UPPER 90S TO NEAR 100 DEGREES BOTH DAYS.
DIFFERENCES IN MEDIUM RANGE MODELS EMERGE OVER THE WEEKEND WITH THE
CHARACTER AND POSITION OF THE UPPER LEVEL RIDGE AND THE EASTWARD
PROGRESSION OF PACIFIC NORTHWEST TROUGH. GFS ENSEMBLE MEAN IS THE
MOST PROGRESSIVE SHIFTING BOTH FEATURES EASTWARD AND PLACING THE
AREA IN SOUTHWESTERLY FLOW ALOFT. IN CONTRAST ECMWF HOLDS THE RIDGE
OVER THE AREA WITH A SLIGHT DEAMPLIFICATION AS A SHORTWAVE TROUGH
MOVES EASTWARD ACROSS THE NORTHERN PLAINS. IN EITHER SCENARIO...A
GENERALLY DRY PATTERN WITH ABOVE NORMAL TEMPERATURES ARE LIKELY TO
PERSIST THROUGH THE WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1039 AM MDT MON AUG 26 2013
VFR CONDITIONS WILL PERSIST AT KGLD AND KMCK FOR THE NEXT 24
HOURS. SUBSIDENCE WILL KEEP A CLEAR SKY ACROSS THE REGION. SOUTH
WINDS WILL BE GUSTY THIS AFTERNOON IN RESPONSE TO A SURFACE TROUGH
IN EASTERN COLORADO. WIND WILL DECREASE SOME TONIGHT BUT WILL
REMAIN OUT OF THE SOUTH.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BRB
AVIATION...FS
AREA FORECAST DISCUSSION
NWS GRAY ME
557 PM EDT MON AUG 26 2013
.SYNOPSIS...
LOW PRESSURE OVER THE EASTERN GREAT LAKES WILL TRACK INTO SOUTHERN
NEW ENGLAND TONIGHT THEN EASTWARD OFF CAPE COD ON TUESDAY. THIS
WILL LEAVE NORTHERN NEW ENGLAND IN A WARM AND HUMID AIR MASS WITH
ISOLATED SHOWERS AND THUNDERSTORMS. A WEAK DISTURBANCE WILL CROSS
THE REGION WEDNESDAY AND THURSDAY FOLLOWED BY A WEAK RIDGE OF HIGH
PRESSURE FRIDAY. A COLD FRONT WILL DROP SOUTH INTO THE REGION
FRIDAY NIGHT AND SATURDAY BEFORE RETURNING NORTH AS A WARM FRONT
FOR SUNDAY. A COLD FRONT WILL CROSS THE AREA ON MONDAY. &&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
UPDATE...
HAVE UPDATED GRIDS BASED ON CURRENT RADAR TRENDS. HAVE LOWERED
POPS OVER MAINE DURING THE EVENING HOURS TO ESSENTIALLY
ZERO...WHILE INCREASING POPS ACROSS SOUTHERN NH. LARGE AREA OF
CONVECTION WILL CONTINUE TO HEAD SOUTHEAST AS PER LATEST HRRR RUNS
SUGGEST. MOST OF THE REMAINDER OF THE AREA WILL REMAIN DRY HOWEVER
FOR MUCH OF THE NIGHT.
HAVE ALSO MADE ADJUSTMENTS TO TEMPERATURE...DEW POINT AND CLOUD
COVER FOR THE NEXT FEW HOURS. THE REST OF THE GRIDDED PACKAGE WILL
REMAIN UNCHANGED.
PREV DISC...
AFTER SOME BREAKS IN THE CLOUDS SOUTHWEST OF THE HIGHER
TERRAIN THIS AFTERNOON, CLOUDS ARE STARTING TO FILL BACK IN. SKIES
SHOULD BE PARTLY TO MOSTLY CLOUDY TONIGHT WITH DEW POINT
TEMPERATURES IN THE 60S, SO PATCHY FOG IS LIKELY. THE MESOSCALE
CONVECTIVE SYSTEM IN WESTERN NEW YORK IS LIKELY TO TRACK THROUGH
SOUTHWESTERN NEW ENGLAND THIS EVENING AND REMAIN SOUTH OF THE
FORECAST AREA. A FEW LIGHT SHOWERS ARE POSSIBLE NEAR THE
MASSACHUSETTS BORDER TOWARD DAYBREAK.
&&
.NEAR TERM /THROUGH TUESDAY/...
AFTER SOME BREAKS IN THE CLOUDS SOUTHWEST OF THE HIGHER TERRAIN
THIS AFTERNOON, CLOUDS ARE STARTING TO FILL BACK IN. SKIES SHOULD
BE PARTLY TO MOSTLY CLOUDY TONIGHT WITH DEW POINT TEMPERATURES IN
THE 60S, SO PATCHY FOG IS LIKELY. THE MESOSCALE CONVECTIVE SYSTEM
IN WESTERN NEW YORK IS LIKELY TO TRACK THROUGH SOUTHWESTERN NEW
ENGLAND THIS EVENING AND REMAIN SOUTH OF THE FORECAST AREA. A FEW
LIGHT SHOWERS ARE POSSIBLE NEAR THE MASSACHUSETTS BORDER TOWARD DAYBREAK.
&&
.SHORT TERM /TUESDAY NIGHT/...
THE WARM AND HUMID AIR MASS REMAINS IN PLACE ON TUESDAY, WITH
AMPLE INSTABILITY FOR THUNDER IN THE AFTERNOON AND EVENING -- IF
WE CAN COUNT ON THE MOUNTAINS TRIGGERING CONVECTION AS THERE
REALLY IS NO DYNAMIC FORCING EXPECTED. HAVE KEPT POPS AS LOW
CHANCE TUESDAY AND TUESDAY NIGHT WITH ONLY LIGHT PRECIPITATION
AMOUNTS EXPECTED. LOW PRESSURE BEGINS TO DEVELOP NEAR SOUTHEASTERN
NEW ENGLAND TUESDAY EVENING BUT SHOULDN`T AFFECT COASTAL NH/ME
UNTIL WEDNESDAY AT THE EARLIEST.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE MODELS ARE IN DECENT AGREEMENT THROUGH FRIDAY BEFORE DIFFERENCES
BEGIN TO EMERGE. THE UPPER HIGH WILL WEAKEN A BIT AND SHIFT FURTHER
WEST AS SERIES OF IMPULSES RIDE OVER THE TOP OF THE RIDGE. BY THE
END OF THE PERIOD...WE TRANSITION TO A HIGHER AMPLITUDE PATTERN
WITH A RIDGE OVER THE WEST-CENTRAL U.S. AND AN EASTERN TROUGH. WE
BEGIN THE PERIOD WITH AN IMPULSE DIVING OVER THE TOP OF THE RIDGE
INTO NEW ENGLAND FOR WEDNESDAY WITH A LINGERING TROUGH AND UNSETTLED
WEATHER INTO THURSDAY. ON FRIDAY...ONLY A SLIGHT CHANCE OF SHOWERS
AS WEAK RIDGING OCCURS AHEAD OF THE NEXT IMPULSE AND AN ASSOCIATED
COLD FRONT THAT DROPS INTO THE REGION FRIDAY NIGHT/EARLY SATURDAY
BEFORE RETURNING NORTH AS A WARM FRONT BY SUNDAY. A COLD FRONT
WILL CROSS THE AREA ON MONDAY.
&&
.AVIATION /22Z MONDAY THROUGH SATURDAY/...
SHORT TERM...MVFR CEILINGS THIS EVENING WILL GIVE WAY TO SCATTERED
IFR/LIFR IN VALLEY FOG. VFR TUESDAY AND TUESDAY NIGHT EXCEPT WHERE
FOG DEVELOPS.
LONG TERM...
WED - THU...SCT MVFR IN SHOWERS AND TSTMS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA THROUGH WEDNESDAY.
LONG TERM...
FRI NIGHT - SAT...WINDS AND SEAS MAY APPROACH SMALL CRAFT OUTSIDE
THE BAYS.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1204 PM EDT MON AUG 26 2013
.SYNOPSIS...
WARMER AND MORE HUMID AIR FOR MUCH OF THE WEEK. A COLD FRONT WILL
BRING SHOWERS AND STORMS TUESDAY AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NO UPDATES MADE TO THE NEAR TERM FORECAST WITH THE NOON UPDATE.
WITH 1030AM UPDATE...MADE MANY SMALL TWEAKS TO THE FORECAST.
UPDATED HOURLY AND MAXIMUM TEMPERATURES WITH LATEST GFSLAMP
GUIDANCE...WHICH SO FAR HAS HAD A GOOD HANDLE OF TEMPERATURE
TRENDS. ALSO BACKED OFF SLIGHTLY ON THE HIGH CIRRUS MOVING IN.
WITH LATEST RUNS OF THE HRRR AND RUC SHOWING THAT ANY
PRECIPITATION THAT AFFECTS THE AREA SHOULD ARRIVE MORE TOWARDS
THE EVENING...HAVE ALSO BACKED OFF POPS SLIGHTLY DURING THE
AFTERNOON TIME PERIOD.
PREVIOUS DISC...AREA LIES ON THE EASTERN PERIPHERY OF STRONG
RIDGE OVER THE CENTRAL STATES. BECAUSE OF THIS...THE DISTRICT IS
IN A PRECARIOUS POSITION WITH NORTHWEST FLOW ALOFT. THIS WILL
BECOME IMPORTANT AS THE WEEK PROGRESSES.
FOR TODAY...THE UPPER LEVEL RIDGE HOLDS FIRM INTO THE AFTERNOON
THEN BEGINS TO RETROGRADE AS A SHORTWAVE TROUGH DIVES DOWN
THROUGH THE GREAT LAKES. THE STRONGEST PART OF THE SHORTWAVE...AND
DEEPEST MOISTURE...WILL MOVE EAST LATE THIS AFTERNOON. WAVE MAY
BE CLOSE ENOUGH TO SPARK A SHOWER OR STORM ACROSS THE NORTH AS
THE EVENING APPROACHES.
HUMIDITY LEVELS AND TEMPERATURES WILL BE ON THE RISE TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
WITH THE NOON UPDATE...HAVE BUMPED UP POPS NORTH OF PITTSBURGH FOR
TONIGHT. 12Z SYNOPTIC MODELS HAVE ALL COME IN WITH MEASURABLE
PRECIPITATION ALONG THE INTERSTATE 80 CORRIDOR...NOW COMING INTO
AGREEMENT WITH SOME OF THE 00Z HIGH-RESOLUTION MODELS. LIKELY POPS
MAY NEED TO COME FARTHER SOUTH...BUT WILL WAIT UNTIL 12Z HIGH-
RESOLUTION MODELS COME OUT TO MAKE THIS DECISION. PREVIOUS
DISCUSSION FOLLOWS.
AT THIS POINT...HAVE LOW CONFIDENCE ON HOW MUCH ACTIVITY WILL
MOVE THROUGH TONIGHT. AS MENTIONED PREVIOUSLY...MOST OF THE UPPER
LEVEL ENERGY AND DEEP MOISTURE WILL MOVE EAST OF THE AREA.
ADDITIONALLY...ATMOSPHERE STABILIZES AND THE LOW LEVEL JET DIVES
INTO EASTERN PA. MODELS ARE INDICATING SOME ACTIVITY HOLDING
TOGETHER OVERNIGHT AS PART OF THE UPPER LEVEL WAVE STRETCHES
WESTWARD. LATEST HIRES MODEL DATA IS SHOWING A LINE OF
SHOWERS/STORMS DEVELOPING ALONG LAKE ERIE THIS EVENING AND THEN
MOVING SOUTHWARD INTO EARLY TUESDAY MORNING. LOW LEVEL MOISTURE
WILL POOL OVER THE UPPER OHIO VALLEY AHEAD OF THE WAVE...BUT WOULD
THINK THAT ACTIVITY WILL DIMINISH AS IT MOVES SOUTHWARD. WILL
CONTINUE WITH THE MENTION OF SCHC/CHC POPS TONIGHT WITH THUNDER
BECOMING LESS PREVALENT LATE TONIGHT.
THIS FIRST WAVE WILL BE OUT OF THE PICTURE TUESDAY MORNING...
ALLOWING FOR A BREAK IN THE ACTIVITY. THANKS TO TONIGHT`S
WAVE...THE RIDGE WILL FURTHER RETROGRADE...PUTTING THE REGION IN
THE PATH OF A SECOND WAVE MOVING SOUTHEASTWARD TUESDAY AFTERNOON.
ATMOSPHERE BECOMES VERY UNSTABLE TUESDAY WITH CAPES OF 2000-3000
J/KG AND LI`S TO AROUND -5. THE K INDEX IS IN THE MID 30S AND THE
MDPI IS AROUND 1. IN ADDITION TO THE ENERGETIC ATMOSPHERE...
SURFACE TDS WILL BE IN THE LOWER 70S LEADING TO PWATS NEAR 1.7. IF
CONVECTION CAN GET GOING...WIND AND HEAVY RAIN WILL BE A THREAT. A
LIMITING FACTOR...PARTICULARLY EARLIER IN THE DAY...WILL BE
RESIDUAL CLOUD COVER. CONVECTIVE TEMPS REMAIN IN THE MID 80S
TUESDAY AND CLOUD COVER MAY MAKE REACHING THESE TEMPS DIFFICULT.
TUESDAYS SHORTWAVE WILL MOVE EASTWARD AND BE FOLLOWED BY ANOTHER
WAVE TUESDAY NIGHT. TUESDAY NIGHT`S WAVE COULD POSSIBLY DEVELOP AN
MCS OVER THE UPPER GREAT LAKES WHICH WOULD DROP DOWN THROUGH THE
AREA. AT THIS POINT...THINK THE GREATER THREAT TUESDAY NIGHT/EARLY
WED WOULD BE WATER RATHER THAN WIND. INSTABILITY WANES...BUT WITH
PWATS NEAR 2 INCHES...ANY CONVECTION WILL PRODUCE HEAVY DOWNPOURS.
THE THREAT FOR STRONG STORMS WILL CONTINUE THROUGH WEDNESDAY AS A
COLD FRONT SINKS THROUGH THE UPPER OHIO VALLEY.
TUESDAY AND WEDNESDAY WILL NEED TO BE CLOSELY MONITORED. IN
GENERAL...WHEN THE AREA LIES ON THE EASTERN EDGE OF A STRONG
RIDGE CAUSING NORTHWEST FLOW ALOFT...OUR WEATHER GETS VERY ACTIVE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
COLD FRONT WILL CLEAR THE AREA WEDNESDAY NIGHT. HIGH PRESSURE WILL
RESUME CONTROL FOR THE REMAINDER OF THE LONG TERM.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
GENL VFR CONDS ARE EXPD THRU THIS EVE WITH INCRG MID/HIGH CLDS.
AREAS OF SHWRS AND TSTMS ASSOCIATED WITH UPR LVL DISTURBANCES WL
DROP SE ACRS THE ERN GT LKS TDA AND TNGT...HOWEVER MUCH OF THIS
SHOULD STAY N AND E OF THE PORTS. FKL/DUJ HAVE THE BEST CHC AT
SEEING A SHWR OR TSTM THIS EVE SO INCLUDED A VCSH MENTION THERE.
LWR SHWR/TSTM CHCS ELSW TNGT...SO NO MENTION OF PCPN AT OTHER
PORTS. FKL/DUJ MAY ALSO SEE A PD OF MVFR CONDS NR SUNRISE TUE
MRNG.
.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
RSTRNS ARE PSBL IN SHWRS/TSTMS TUE AFTN THRU WED AS A CDFNT
CROSSES THE RGN. VFR RTNS WITH HIGH PRES THU AND FRI.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
440 PM EDT MON AUG 26 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 418 PM EDT MON AUG 26 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE
CENTERED OVER MO/KS RESULTING IN ACYC FLOW FROM THE NRN PLAINS
THROUGH THE UPPER MS VALLEY INTO THE GREAT LAKES. WAA IN ADVANCE OF
AN UPSTREAM SHORTWAVE TROUGH MOVING INTO SW NORTH DAKOTA SUPPORTED
AN AREA OF LIGHT TO MODERATE RAIN WITH ONLY ISOLD TSRA. AT THE
SFC...THE CONVECTION THIS MORNING HELPED PUSH THE WEAK FRONTAL
BOUNDARY INTO NRN WI AND EXTENDED FROM NEAR HYR TO GRB. TEMPS TO THE
SOUTH OF THE FRONT HAVE AGAIN CLIMBED TO AROUND 90 WHILE MORE
MODERATE READINGS IN THE LOW TO MID 80S PREVAILED TO THE NORTH.
DEWPOINTS THROUGH THE REGION WERE NEAR 70F WITH 12Z OBSERVED AND
FCST SOUNDINGS SHOWING PWAT VALUES AROUND 2.0 INCHES(200 PCT OF
NORMAL).
EXPECT THAT AS THE ND SHRTWV MOVES TO THE EAST AND WAA INCREASES
THIS EVENING...EXPECT SHRA/TSRA TO DEVELOP AND QUICKLY IN INCREASE
IN COVERAGE BY LATE EVENING IN THE VCNTY OF THE SFC-800 MB FRONT
FROM CNTRL MN INTO NW WI. EVEN THOUGH THE MODELS HAVE TRENDED
FARTHER SOUTH WITH THE PCPN AND SHOW THE MOST FAVORABLE 310K
ISENTROPIC LIFT REMAINING SOUTH OF THE CWA...THERE IS STILL
CONSIDERABLE UNCERTAINTY ON THE LOCATION OF THE STRONGEST CONVECTION.
MOST OF THE HIGHER RES MODELS KEEP NEARLY ALL THE PCPN SOUTH OF
THE CWA WHILE THE GFS/ECMWF AND HIGH RES RAPID REFRESH BRING PCPN
THROUGH MAINLY THE SW HALF OF THE CWA. SO...THE HIGHER POPS/QPF WERE
SHIFTED TO THE SOUTH WITH LOCATIONS ALONG THE WI BORDER SEEING THE
GREATEST POTENTIAL FOR STRONG TSRA.
WITH MUCAPE VALUES INTO THE 1000-1500 J/KG RANGE AND EFFECTIVE SHEAR
TO AROUND 30 KT...THERE IS THE POTENTIAL FOR MULTICELL CLUSTERS THAT
COULD PRODUCE VERY HEAVY RAIN AND LCL WIND DAMAGE...SIMILAR TO LAST
NIGHT. FCST CORFIDI VECTORS SUGGEST THAT STORM ELEMENTS SHOULD KEEP
ENOUGH FORWARD MOTION TO LIMIT POTENTIAL FOR EXCESSIVE RAINFALL.
HOWEVER...ONE TO TWO INCHES AMOUNTS MAY AGAIN BE COMMON ALONG THE
PATH OF HEAVIER CLUSTERS. ANY LEFTOVER SHRA/TSRA TUE MORNING OVER
MAINLY THE S CNTRL CWA IS EXPECTED TO DIMINISH AND SAG OFF TO THE SE
BY EARLY TO MID AFTERNOON.
WITH 850 MB TEMPS REMAINING AROUND 18C...MAX TEMPS SHOULD ALSO BE
SIMILAR TO TODAY WITH HIGHS INTO THE LOW TO MID 80S WITH SLIGHTLY
COOLER READINGS ALONG THE GREAT LAKES.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 439 PM EDT MON AUG 26 2013
NO SIGNIFICANT RELIEF FROM THE WARM WEATHER. AVERAGE HIGH
TEMPERATURES THIS TIME OF YEAR ARE IN THE MID 70S FOR MUCH OF UPPER
MICHIGAN. TEMPERATURES SHOULD REMAIN 5-10F ABOVE NORMAL THROUGH THE
WEEKEND. WE CAN BASICALLY EXPECT QUIET WEATHER UNTIL THURSDAY
NIGHT...AS THE DOMINANT 500MB HIGH REMAINS OVER MUCH OF THE CENTRAL
AND SOUTHERN U.S. THE NEXT SHORTWAVE TO ROUND THE RIDGE IS CURRENTLY
MOVING IN OVER THE SW STATES...ALONG THE BAJA AND S CA SHORE THIS
AFTERNOON...HELPING PRODUCE A STRING OF SHOWERS AND A FEW
THUNDERSTORMS.
THE SHORTWAVE WILL TOP THE RIDGE ACROSS ND WEDNESDAY
AFTERNOON/EVENING...BEFORE PUSHING INTO N MN WEDNESDAY NIGHT/EARLY
THURSDAY. KEPT THE MENTION OF CHANCE RA AND SLIGHT CHANCE TS IN THE
FCST FOR THE FAR W THURSDAY AFTERNOON...SLIDING OVERHEAD THURSDAY
NIGHT...AND ENDING FRIDAY.
ANOTHER GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
SATURDAY AFTERNOON/EVENING THROUGH THE REST OF THE WEEKEND...IN
ADVANCE OF A DEEPENING SFC LOW ACROSS S CENTRAL CANADA. EXPECT THE
LOW TO SLIDE INTO ONTARIO SATURDAY NIGHT...AND EXIT INTO QUEBEC
SUNDAY AFTERNOON /AS SHOWN ON THE 26/12 ECMWF/. THE GFS IS ROUGHLY
12HRS SLOWER. BEHIND THE COLD FRONT THERE WILL LIKELY BE A
COOL-DOWN. IF NOTHING ELSE A TEMPORARY RETURN TO NEAR NORMAL
TEMPERATURES LOOK LIKELY MONDAY AFTERNOON. THE OPERATIONAL ECMWF
CAME IN WITH UPPER 50S TO MID 60S ON COOL NW FLOW. WHILE 50S DO NOT
LOOK ALL THAT LIKELY MID 60S WILL BE POSSIBLE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 143 PM EDT MON AUG 26 2013
A SFC TROUGH/VERY WEAK COLD FRONT THAT TRIGGERED SHRA/TSRA EARLIER
THIS MORNING HAS MOVED SOUTH INTO NORTHERN WISCONSIN. EXPECT MOSTLY
DRY/VFR CONDITIONS INTO THIS EVENING THEN LATER TONIGHT MORE
SHRA/TSRA COULD IMPACT THE REGION YET AGAIN. HOWEVER...THE BEST
CHANCE OF SHRA/TSRA IS EXPECTED TO REMAIN FARTHER TO THE SOUTH AND
WEST...WITH IWD SEEING THE GREATEST SHRA/TSRA POTENTIAL. VCTS
WAS INCLUDED AT IWD AS A START TO HINT AT THE EXPECTED TIMING OF THE
SHRA/TSRA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 418 PM EDT MON AUG 26 2013
WINDS LESS THAN 20 KTS EXPECTED ACROSS LK SUPERIOR MUCH OF THIS
WEEK. THE ONLY EXCEPTION WOULD BE WHEN STRONGER THUNDERSTORMS ROLL
ACROSS THE WRN LAKE AND PRODUCE STRONGER GUSTS...AS HAS BEEN SEEN
THE LAST SEVERAL DAYS. OTHER THAN THOSE THUNDERSTORMS...GIVEN THE
WARM AND HUMID AIRMASS IN PLACE ALONG WITH ADDITIONAL MOISTURE FROM
SHOWERS AND THUNDERSTORMS...AREAS OF DENSE FOG WILL BE THE OTHER
MAIN CONCERN THROUGH MUCH OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
424 PM EDT MON AUG 26 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 418 PM EDT MON AUG 26 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE
CENTERED OVER MO/KS RESULTING IN ACYC FLOW FROM THE NRN PLAINS
THROUGH THE UPPER MS VALLEY INTO THE GREAT LAKES. WAA IN ADVANCE OF
AN UPSTREAM SHORTWAVE TROUGH MOVING INTO SW NORTH DAKOTA SUPPORTED
AN AREA OF LIGHT TO MODERATE RAIN WITH ONLY ISOLD TSRA. AT THE
SFC...THE CONVECTION THIS MORNING HELPED PUSH THE WEAK FRONTAL
BOUNDARY INTO NRN WI AND EXTENDED FROM NEAR HYR TO GRB. TEMPS TO THE
SOUTH OF THE FRONT HAVE AGAIN CLIMBED TO AROUND 90 WHILE MORE
MODERATE READINGS IN THE LOW TO MID 80S PREVAILED TO THE NORTH.
DEWPOINTS THROUGH THE REGION WERE NEAR 70F WITH 12Z OBSERVED AND
FCST SOUNDINGS SHOWING PWAT VALUES AROUND 2.0 INCHES(200 PCT OF
NORMAL).
EXPECT THAT AS THE ND SHRTWV MOVES TO THE EAST AND WAA INCREASES
THIS EVENING...EXPECT SHRA/TSRA TO DEVELOP AND QUICKLY IN INCREASE
IN COVERAGE BY LATE EVENING IN THE VCNTY OF THE SFC-800 MB FRONT
FROM CNTRL MN INTO NW WI. EVEN THOUGH THE MODELS HAVE TRENDED
FARTHER SOUTH WITH THE PCPN AND SHOW THE MOST FAVORABLE 310K
ISENTROPIC LIFT REMAINING SOUTH OF THE CWA...THERE IS STILL
CONSIDERABLE UNCERTAINTY ON THE LOCATION OF THE STRONGEST CONVECTION.
MOST OF THE HIGHER RES MODELS KEEP NEARLY ALL THE PCPN SOUTH OF
THE CWA WHILE THE GFS/ECMWF AND HIGH RES RAPID REFRESH BRING PCPN
THROUGH MAINLY THE SW HALF OF THE CWA. SO...THE HIGHER POPS/QPF WERE
SHIFTED TO THE SOUTH WITH LOCATIONS ALONG THE WI BORDER SEEING THE
GREATEST POTENTIAL FOR STRONG TSRA.
WITH MUCAPE VALUES INTO THE 1000-1500 J/KG RANGE AND EFFECTIVE SHEAR
TO AROUND 30 KT...THERE IS THE POTENTIAL FOR MULTICELL CLUSTERS THAT
COULD PRODUCE VERY HEAVY RAIN AND LCL WIND DAMAGE...SIMILAR TO LAST
NIGHT. FCST CORFIDI VECTORS SUGGEST THAT STORM ELEMENTS SHOULD KEEP
ENOUGH FORWARD MOTION TO LIMIT POTENTIAL FOR EXCESSIVE RAINFALL.
HOWEVER...ONE TO TWO INCHES AMOUNTS MAY AGAIN BE COMMON ALONG THE
PATH OF HEAVIER CLUSTERS. ANY LEFTOVER SHRA/TSRA TUE MORNING OVER
MAINLY THE S CNTRL CWA IS EXPECTED TO DIMINISH AND SAG OFF TO THE SE
BY EARLY TO MID AFTERNOON.
WITH 850 MB TEMPS REMAINING AROUND 18C...MAX TEMPS SHOULD ALSO BE
SIMILAR TO TODAY WITH HIGHS INTO THE LOW TO MID 80S WITH SLIGHTLY
COOLER READINGS ALONG THE GREAT LAKES.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 429 AM EDT MON AUG 26 2013
AS HAS BEEN THE CASE OVER THE LAST COUPLE OF DAYS...MODELS REMAIN IN
GOOD AGREEMENT WITH THE LARGE SCALE PATTERN OF AN UPPER HIGH
SPINNING OVER KANSAS/MISSOURI THROUGH MUCH OF THIS WEEK BEFORE
GRADUALLY WEAKENING TOWARDS THE WEEKEND. WHERE THEY HAVE BEEN
STRUGGLING IS WITH THE SMALLER SCALE DISTURBANCES ROTATING AROUND
THE HIGH AND INFLUENCING THE UPPER GREAT LAKES REGION.
FORTUNATELY...MODELS HAVE COME INTO BETTER AGREEMENT WITH A
SHORTWAVE ASSOCIATED WITH THE REMNANTS OF TROPICAL STORM IVO IN THE
EASTERN PACIFIC ROTATING AROUND THE UPPER RIDGE AND INFLUENCING THE
AREA TONIGHT INTO TUESDAY. THIS SHORTWAVE WILL BE ROUNDING THROUGH
THE DAKOTAS AND NORTHERN MINNESOTA TONIGHT AND THEN ACROSS UPPER
MICHIGAN ON TUESDAY MORNING. IN ADDITION...THERE IS BETTER AGREEMENT
ON THE TRACK OF THE LOW AND ASSOCIATED WARM FRONT EXITING THE
DAKOTAS...WITH THE QPF FIELDS NOW ONLY HAVING A SPREAD OF A
150 MILES COMPARED TO 300 MILES BEFORE. THE CONSENSUS IS THE
PRECIPITATION FOCUSED MORE OVER NORTH CENTRAL MINNESOTA...UPPER
MICHIGAN AND NORTHERN WISCONSIN. WITH THE CONVECTION THAT WILL
LIKELY BE ONGOING ON THE STALLED BOUNDARY STRETCHING FROM NORTHERN
WISCONSIN EAST-NORTHEAST INTO NORTH CENTRAL MINNESOTA AND EASTERN
NORTH DAKOTA...THE QUESTION COMES ON IF THAT CONVECTION BEING SOUTH
OF THE AREA INITIALLY WILL BE ENOUGH TO KEEP THE CONVECTION
ASSOCIATED WITH THE SHORTWAVE SOUTH. THINK THE CONVECTION BEING
SOUTH IS A REASONABLE IDEA AT LEAST INITIALLY TONIGHT...BUT WITH THE
SHORTWAVE TRACKING FARTHER TO THE NORTH AND STORM MOTIONS AND
FORWARD PROP CORFIDI VECTORS FROM ANY STORMS IN MINNESOTA PUSHING
EAST...BELIEVE THAT AT LEAST THE SOUTH HALF OF THE CWA (INCLUDING
MOST OF UPPER MICHIGAN) WILL BE AFFECTED BY THE CONVECTION MOVING
THROUGH. MID-LEVEL MOISTURE TRANSPORT INCREASES CONFIDENCE
IN THAT IDEA...WITH IT SUPPORTING BOTH THE INITIAL CONVECTION
ALONG THE EXISTING BOUNDARY AND THEN REFOCUSING MORE OVER THE U.P.
TOWARDS TUESDAY MORNING WITH THE SHORTWAVE. OVERALL...KEPT THE
GENERAL IDEA FROM THE PREVIOUS SHIFT...BUT CONTINUED THE SLIGHT
SOUTHWARD TREND STARTED YESTERDAY TO THE HIGHEST POPS.
HEAVY RAIN WILL BE THE LARGEST THREAT TUESDAY MORNING...WITH MODELS
CONTINUING TO SHOW PWATS OF 200-250 PERCENT OF NORMAL AND FREEZING
LEVELS OF 14.5-15KFT. BUT SINCE 0-6KM SHEAR VALUES OF 35KTS WOULD
SUPPORT SOME ORGANIZATION...COULD SEE DAMAGING WINDS (AND LARGE HAIL
INITIALLY) IN THE STRONGER STORMS OR LINES THAT DEVELOP.
THE SHORTWAVE AND CONVECTION WILL DEPART FROM WEST TO EAST ON
TUESDAY AFTERNOON AND EARLY EVENING AND HAVE FOLLOWED THAT IDEA FOR
POPS. THEN...WITH THE WEAK LOW MOVING EAST AND A HIGH PRESSURE
RIDGE NOSING SOUTH FROM A HIGH CENTERED OVER HUDSON BAY...NORTHERLY
FLOW WILL DEVELOP OVER THE AREA TUESDAY NIGHT AND REMAIN INTO
WEDNESDAY MORNING. ASSUMING THAT THERE WILL BE FOG OVER LAKE
SUPERIOR AND THIS NORTHWESTERLY FLOW WILL PUSH IT SOUTH AND OVER
LOCATIONS NEAR LAKE SUPERIOR BY DAYBREAK WEDNESDAY. THIS WILL
LIKELY CONTINUE THROUGH THE MORNING HOURS ON WEDNESDAY...EITHER AS
FOG OR LOW STRATUS. ALTHOUGH THIS MOISTURE WILL BE VERY
SHALLOW...SOME OF THE MODELS ARE GIVING THE TELL TALE BLOTCHY 0.01
OF QPF USUALLY NOTED WITH THESE TYPES OF FOG EVENTS OVER THE GREAT
LAKES. FEEL LIKE WE/VE HAD A DECENT HANDLE ON THIS IDEA OVER THE
LAST SEVERAL SHIFTS...SO ONLY MADE MINOR TWEAKS TO THE GOING
FORECAST.
THE HIGH PRESSURE RIDGE WILL SLIDE ACROSS THE AREA ON WEDNESDAY
AFTERNOON/NIGHT AND THEN SHIFT SOUTHEAST ON THURSDAY. THIS SHOULD
GIVE THE AREA DRY...SLIGHTLY COOLER...AND LESS HUMID WEATHER.
COOLEST TEMPERATURES ON WEDNESDAY WILL BE NEAR LAKE SUPERIOR
(HIGHS IN THE MID 70S) WHERE THE CLOUDS/FOG WILL HANG ON LONGEST.
OVER THE SOUTH CENTRAL...LINGERING WARM AIR ALOFT AND MORE SUNSHINE
WILL PUSH TEMPS INTO AT LEAST THE MID 80S. HIGHS THURSDAY WILL BE A
TOUCH WARMER...ESPECIALLY NEAR THE GREAT LAKES AS SOUTHWESTERLY
FLOW BEGINS TO INCREASE WITH THE HIGH EXITING.
FOR THURSDAY AFTERNOON INTO THURSDAY NIGHT...MODELS CONTINUE TO
SHOW A SHORTWAVE ROUNDING THE UPPER RIDGE AND MOVING THROUGH THE
UPPER GREAT LAKES BUT STILL DIFFER SOMEWHAT ON THE LOCATION. WILL
HANDLE WITH SLIGHT CHANCE POPS FOR NOW OVER THE SOUTHWEST
HALF OF THE CWA...UNTIL THERE IS BETTER AGREEMENT ON PCPN CHANCES.
FROM FRIDAY NIGHT ON...THE SMALLER SCALE FEATURES DIFFER BUT THE
GENERAL IDEA OF THE UPPER RIDGE BREAKING DOWN SOME AND THE TROUGH
OVER THE PACIFIC NORTHWEST SLOWLY SHIFTING EAST WHILE EJECTING
ADDITIONAL SHORTWAVES IS CONSISTENT IN THE MODELS. THIS WILL PUT
THE AREA UNDER ADDITIONAL CHANCES FOR PRECIPITATION FOR THE LABOR
DAY WEEKEND. DUE TO THE LIMITED SKILL ON TIMING...WILL JUST GO WITH
SLIGHT AND CHANCE POPS AT THIS POINT. ALSO...TEMPERATURES SHOULD
REMAIN ABOVE NORMAL THIS WEEKEND...WITH 850MB TEMPS SOMEWHERE
BETWEEN 18-23C.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 143 PM EDT MON AUG 26 2013
A SFC TROUGH/VERY WEAK COLD FRONT THAT TRIGGERED SHRA/TSRA EARLIER
THIS MORNING HAS MOVED SOUTH INTO NORTHERN WISCONSIN. EXPECT MOSTLY
DRY/VFR CONDITIONS INTO THIS EVENING THEN LATER TONIGHT MORE
SHRA/TSRA COULD IMPACT THE REGION YET AGAIN. HOWEVER...THE BEST
CHANCE OF SHRA/TSRA IS EXPECTED TO REMAIN FARTHER TO THE SOUTH AND
WEST...WITH IWD SEEING THE GREATEST SHRA/TSRA POTENTIAL. VCTS
WAS INCLUDED AT IWD AS A START TO HINT AT THE EXPECTED TIMING OF THE
SHRA/TSRA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 418 PM EDT MON AUG 26 2013
WINDS LESS THAN 20 KTS EXPECTED ACROSS LK SUPERIOR MUCH OF THIS
WEEK. THE ONLY EXCEPTION WOULD BE WHEN STRONGER THUNDERSTORMS ROLL
ACROSS THE WRN LAKE AND PRODUCE STRONGER GUSTS...AS HAS BEEN SEEN
THE LAST SEVERAL DAYS. OTHER THAN THOSE THUNDERSTORMS...GIVEN THE
WARM AND HUMID AIRMASS IN PLACE ALONG WITH ADDITIONAL MOISTURE FROM
SHOWERS AND THUNDERSTORMS...AREAS OF DENSE FOG WILL BE THE OTHER
MAIN CONCERN THROUGH MUCH OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
149 PM EDT MON AUG 26 2013
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 344 AM EDT MON AUG 26 2013
WARM AND HUMID DAYS WILL CONTINUE TODAY AND TUESDAY. HOWEVER A COLD
FRONT WILL PASS THROUGH THE REGION TUESDAY NIGHT...BRINGING A GOOD
CHANCE FOR STORMS AS WELL AS LESS HUMID AIR INTO THE AREA BY
WEDNESDAY.
TEMPERATURES ARE EXPECTED TO REMAIN 85 TO 90 INTO THE WEEKEND
WITH ANOTHER CHANCE FOR RAIN BY FRIDAY NIGHT INTO SUNDAY.
&&
.UPDATE...
ISSUED AT 1115 AM EDT MON AUG 26 2013
THE CONVECTION THIS MORNING IS EXPECTED TO WEAKEN INTO THIS
AFTERNOON AS THE SHORTWAVE THAT HELPED CREATE IT MOVE EAST OVER
CENTRAL LOWER MICHIGAN RESULTING IN DPVA OVER OUR AREA. THE
OUTFLOW BOUNDARY IS MOVING INTO MORE STABLE AIR SO I DO NOT THINK
THERE WILL BE SIGNIFICANT REDEVELOPMENT SOUTH OF INTERSTATE 96
THIS AFTERNOON. SO I FEATURE DECREASING POPS DURING THE AFTERNOON
TO SHOW THE DECREASING THREAT FOR STORMS INTO THE LATE AFTERNOON.
UPDATE ISSUED AT 853 AM EDT MON AUG 26 2013
I UPDATED THE GRIDS AND ZONE FORECAST TO TRACK THE LINE OF
THUNDERSTORMS SOUTHEAST ACROSS THE CENTRAL CWA BASED ON A
COMBINATION OF THE TIMING TOOL AND THE HRRR RUC (10Z). THIS WOULD
BRING THE STORMS TO NEAR LANSING AROUND 1045 AM THIS MORNING. THE
LOW LEVEL JET SPEED MAX IS JUST IN FRONT OF THIS LINE OF STORMS.
IT WEAKENS AS THE DAY PROGRESSES AND SHIFTS SOUTHEAST (RAP 11Z).
BY NOON THE CORE IS ONLY 30 KNOTS AND OVER MONTCALM AND GRATIOT
COUNTIES SO THE STORMS SHOULD HAVE A HARD TIME GETTING TO MUCH
FARTHER SOUTH THAN THAT.
I WILL HAVE TO WATCH WHAT HAPPENS FOR THIS AFTERNOON AS THE
VERTICAL TOTALS SOUTH OF ROUTE 10 ARE NEAR 29C AND THE 850 TO 500
MB LAPSE RATE IS NEAR 8C. SEEMS MORE STORMS ARE POSSIBLE THIS
AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 344 AM EDT MON AUG 26 2013
SEVERAL CHALLENGES IN THE SHORT TERM. FIRST WILL BE JUST HOW HOT
THE REGION GETS. THIS WILL LARGELY DEPEND ON THE AMOUNT OF SUNSHINE
WE GET...OR IF THE DEBRIS CLOUDS WIN OUT. SECONDLY WILL BE THE
INCREASING CHANCES FOR SHOWERS AND STORMS AS THE UPPER RIDGE WEAKENS
AND DRIFTS SOUTH WITH TIME.
HAVE DECIDED TO HOLD FAIRLY CONSISTENT WITH THE TEMP FORECAST
DESPITE A LARGE AREA OF DEBRIS CLOUDS UPSTREAM EARLY THIS MORNING.
MID/HI CLOUDS WILL SPREAD IN FROM THE THUNDERSTORM CLUSTER THAT
WAS OVER THE NORTHERN GREAT LAKES. IT APPEARS THERE IS ENOUGH
RIDGING IN PLACE TO THIN THESE CLOUDS WITH TIME AND MAX TEMPS
AROUND 90 STILL LOOK OK FOR TODAY. EXPECT A SIMILAR SETUP INTO
TUESDAY...AND HAVE MAINTAINED MAX TEMPS AROUND 90 AGAIN. TUESDAY
SHOULD BE THE WARMEST DAY CONSIDERING DEW POINTS WILL BE
HIGHER...DRIVING HEAT INDEX READINGS INTO THE MID AND UPPER 90S.
TEMPS WILL ONLY BE A COUPLE DEGREES COOLER ON WED AS A FRONT
PASSES THROUGH...ALSO BRINGING SLIGHTLY LOWER DEW POINTS.
AS FOR SHOWERS AND STORMS...THE CENTER OF THE UPPER HIGH WILL BE
NEAR KANSAS CITY TODAY AND IT WILL SLOWLY SINK SOUTH THROUGH WED.
IT/S INFLUENCES WILL SLOWLY LOSE ITS GRIP ON THE GREAT LAKES...AND
THE RING OF CONVECTION AROUND THIS RIDGE SHOULD GRADUALLY EASE INTO
THE CWA THROUGH THE SHORT TERM. AT THE SURFACE THE MODELS ARE IN
GOOD AGREEMENT PUSHING A COLD FRONT THROUGH HERE TUESDAY NIGHT.
THE BEST JET DYNAMICS STAYS TO OUR NORTH AND WEST TODAY AND TONIGHT.
SO FEEL ANY SHOWERS AND STORMS THAT REACHES THE GRR CWA WILL BE IN A
WEAKENING STATE AS THEY RUN AWAY FROM THE BEST DYNAMICS AND INTO THE
RIDGE. HOWEVER A LOW LEVEL JET IS POISED TO PUSH IN AHEAD OF THE
COLD FRONT BY TUESDAY AFTERNOON INTO THE EVENING. THIS APPEARS TO
BE THE BEST CHANCE FOR PCPN AND HAVE RAISED POPS TO LIKELY ACROSS
MUCH OF THE CWA. SEVERE STORMS WILL BE POSSIBLE FROM ROUGHLY MID
AFTERNOON THROUGH ABOUT MIDNIGHT. DAMAGING WIND WILL BE THE MAIN
THREAT WILL SOME LARGE HAIL POSSIBLE.
THE FRONT SHOULD BE THROUGH THE CWA BY WED MORNING AND HAVE
MAINTAINED A DRY FORECAST. NOT MUCH COOLER BEHIND THE FRONT...WITH
HEAT INDEX READINGS ONLY RETREATING TO AROUND 90.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 344 AM EDT MON AUG 26 2013
MODELS ARE CONSISTENT IN SHOWING THE PLAINS RIDGE HANGING ON THROUGH
THE LONG TERM WITH NORTHWEST FLOW IN PLACE OVER THE GREAT LAKES.
500MB HEIGHTS WILL BE HIGH ENOUGH (580S DM/S) AND 850MB TEMPS WARM
ENOUGH (+16C TO +20C) THAT HIGH TEMPS WILL REMAIN IN THE MIDDLE 80S
TO AROUND 90.
MAIN ISSUE WILL BE TRYING TO TIME ANY PRECIPITATION INTO THE AREA AS
SHORTWAVE ENERGY SLIDES SOUTHEAST IN THE NORTHWEST UPPER FLOW.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT LOOK DRY WITH HIGH PRESSURE
IN PLACE BEHIND WEDNESDAY/S FROPA. FRIDAY AND FRIDAY NIGHT...BOTH
THE GFS AND THE ECMWF ARE INSISTENT THAT A WARM FRONT WILL BE NEARBY
WITH PRECIPITATION IN THE AREA. NOT CONFIDENT IN THIS SCENARIO...SO
ONLY HAVE 20 PCT POPS IN THE FORECAST. KEPT THE FORECAST DRY
SATURDAY AND SATURDAY NIGHT WITH ANOTHER 20 PCT CHANCE FOR SHOWERS
AND STORMS ON SUNDAY. THE ECMWF AND GFS DIVERGE ON SURFACE FEATURES
FOR NEXT SUNDAY. OPTED TO FOLLOW THE GFS HERE AND HAVE A SMALL
CHANCE IN THE FORECAST AS ANOTHER WARM FRONT IS PROGD IN THE AREA.
OVERALL..THE LONG TERM PERIOD LOOKS TO REMAIN WARM WITH ABOVE NORMAL
TEMPERATURES. PRECIPITATION CHANCES ARE A TOUGH CALL...BUT IT
APPEARS SMALL CHANCES FOR SHOWERS AND STORMS EXIST BOTH FRIDAY AND
SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 148 PM EDT MON AUG 26 2013
BIGGEST CONCERN IN THE 18Z FCSTS IS CONVECTIVE TRENDS THROUGH THE
PERIOD. CONVECTION THAT TRIED TO MOVE SOUTH INTO THE AREA THIS
MORNING HAS NOW JUST ABOUT TOTALLY DISSIPATED AS OF 1730Z. THE
AREA HAS BEEN LEFT WITH THE MAINLY MID AND HIGH CLOUD COVER LEFT
OVER FROM IT.
THE MAJORITY OF THE MOST RECENT HIGH RESOLUTION MODELS INDICATE
CONVECTION TRYING TO REFORM ACROSS NE WISCONSIN AND TO NEAR THE
KLDM AREA AROUND 23-02Z TIME FRAME. NOT SURE IT WILL DEVELOP DUE
TO THE COOL AIR MASS LEFT BEHIND BY THIS MORNING/S STORMS. WE WILL
ACCOUNT FOR IT WITH A VCTS BEGINNING AROUND 03Z AT KMKG AND KGRR WITH
IT EXPECTED TO SLIDE SOUTH THEREAFTER THROUGH 07-08Z.
IT IS NOT OUT OF THE REALM OF POSSIBILITIES WE COULD HAVE STORMS
AT ANY TIME AT THE SITES AFTER THAT THROUGH THE NIGHT. HOWEVER THE
NEXT BEST CHC OF STORMS LOOKS TO COME AFTER 14Z TUE AS A STORM
COMPLEX ROLLS OUT OF WISCONSIN AND INTO LOWER MI. WE WILL HIT THIS
CHC WITH A VCTS ALSO. ANY STORMS COULD SEE CONDITIONS LOWER
LOCALLY INTO THE IFR CATEGORY.
&&
.MARINE...
ISSUED AT 344 AM EDT MON AUG 26 2013
SOUTHWEST FLOW WILL CONTINUE TO BRING SCA CONDITIONS TODAY. HOWEVER
AS THE FRONT APPROACHES WINDS WILL SLOWLY WEAKEN. FEEL CONDITIONS
WILL IMPROVE TOWARD EVENING...AND AS SUCH...MOVED UP THE ENDING OF
THE SCA.
ANOTHER PERIOD OF HIGHER WINDS AND WAVES WILL OCCUR BEHIND THE FRONT
FOR LATE TUESDAY NIGHT INTO WEDNESDAY WHEN ANOTHER SCA MAY BE NEEDED
WITH A NORTHERLY FLOW.
&&
.HYDROLOGY...
ISSUED AT 344 AM EDT MON AUG 26 2013
MOST AREAS SHOULD SEE BETWEEN A HALF INCH AND ONE INCH OF RAIN
THROUGH TUESDAY NIGHT. THE HIGHEST TOTALS SHOULD BE ACROSS THE
NORTHERN CWA. THIS HAS BEEN THE DRIER AREA...A SHOULD BE ABLE TO
HANDLE THIS AMOUNT OF RAIN. LOCALIZED POOR DRAINAGE FLOODING WILL BE
POSSIBLE IN PERSISTENT STORMS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 6 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...DUKE
AVIATION...NJJ
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
600 PM CDT MON AUG 26 2013
.UPDATE...
ISSUED AT 600 PM CDT MON AUG 26 2013
AS OF 2245 UTC...STRONG TO SEVERE THUNDERSTORMS CONTINUE TO
INTENSIFY ACROSS FAR NORTHEAST MONTANA THROUGH DUNN COUNTY IN
NORTH DAKOTA ALONG A WEAK CONVERGENCE LINE. ML CAPE VALUES NEAR
2500 J/KG ARE ANALYZED ALONG THIS LINE ON THE SPC RAPV2
MESOANALYSIS...WHICH APPEARS TO BE HANDLING THE CURRENT
ENVIRONMENT BETTER THAN THE RAPV1. GIVEN DEEP LAYER SHEAR OF 40
KTS...SUPERCELLS ARE LIKELY. THE PRIMARY THREATS ARE DAMAGING
WINDS WITH DOWNDRAFT CAPE VALUES NEAR 1200 J/KG. GIVEN THE HIGH
FREEZING LEVELS AND PWATS...HAIL SURVIVABILITY IS LIMITED. ALSO
MONITORING LOCATIONS NEAR THE SOUTH DAKOTA BORDER ALONG ANOTHER
CONVERGENCE LINE IN A SIMILIAR ENVIRONMENT...WITH THE LATEST 21
UTC HRRR CONTINUING TO SUGGEST CONTINUED GROWTH OF CONVECTION THAT
HAS BEEN INITIATING OVER THE PAST HOUR FOR THESE AREAS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 324 PM CDT MON AUG 26 2013
MAIN CONCERNS THIS SHORT TERM WILL BE THUNDERSTORMS. BROAD FEATURES
INCLUDE A LARGE AND PERSISTENT RIDGE IN THE UPPER ATMOSPHERE. ON THE
WESTERN SIDE OF THE RIDGE A TROPICAL PLUME IS IDENTIFIED ON THE
WATER VAPOR IMAGE. A WEAK SHORTWAVE NOW MOVING THROUGH NORTHEAST
WYOMING WILL SUPPORT CONVECTION THIS EVENING AND OVERNIGHT. AS THE
SHORT WAVE TROUGH TRANSITS ACROSS THE RIDGE EXPECT AN INCREASE IN
THUNDERSTORMS ...WHICH SO FAR TODAY APPEAR TO BY LIMITED BY THE WARM
MID LEVEL TEMPERATURES. WITH THE ADDED LIFT FROM THE SHORTWAVE
EXPECT THUNDERSTORMS TO BECOME MORE ACTIVE LATE THIS AFTERNOON AND
EVENING...MAINLY SOUTH CENTRAL AND SOUTHEAST. MULTIPLE WEAK OUTFLOW
BOUNDARIES EXIST ACROSS THE SOUTH CENTRAL...AND CLOUDS ACROSS NORTH
DAKOTA SUPPORTING DIFFERENTIAL HEATING AND ENHANCING THE THERMAL
BOUNDARY.
TONIGHT...THUNDERSTORM THREAT WILL MOVE EAST. ENDED THE CHANCE OF
THUNDERSTORMS AFTER 1 AM. SOUTHEAST UPSLOPE FLOW AND WEAK SHORTWAVE
ENERGY IN FLOW ALOFT WILL SUPPORT A SLIGHT CHANCE OF THUNDERSTORMS
SOUTHWEST TUESDAY AFTERNOON.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 324 PM CDT MON AUG 26 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THE OVERALL UPPER LEVEL PATTERN REMAINS NEARLY UNCHANGED WITH A
CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND DETERMINISTIC
MODELS. FINER DETAILS CONTINUE TO COME TO A CONSENSUS AMONG THE
MODELS EARLY IN THE PERIOD...BUT SIGNIFICANT DIFFERENCES STILL EXIST
OVER THE WEEKEND AND EARLY NEXT WEEK. EXCEPT FOR A FEW ADJUSTMENTS
TO BUMP UP POPS WHERE MODELS ARE MORE IN LINE...STILL UTILIZED A
MODEL BLEND SOLUTION FOR POPS DURING MOST OF THE LONG TERM PERIOD.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...BETTER THUNDERSTORM CHANCES
APPEAR IN STORE TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WHEN A FEW
UPPER LEVEL WAVES MOVE INTO THE NORTHERN PLAINS AND TEMPORARILY
BREAKS DOWN THE UPPER LEVEL RIDGE. DETERMINISTIC MODELS INDICATE
INCREASED WARM ADVECTION WEDNESDAY AFTERNOON AND EVENING AHEAD OF
SURFACE LOW PRESSURE THAT DEVELOPS OVER THE WESTERN DAKOTAS. POPS
ARE GREATEST WEDNESDAY IN THE WEST HALF DURING THE DAY...WITH HIGHER
CHANCE POPS SPREADING EAST WEDNESDAY NIGHT AS THE INCREASED WARM
ADVECTION AND COOLING UPPER LEVEL TEMPERATURES WITH THE SHORTWAVES
SHOULD SUSTAIN CONVECTION AS IT TRANSLATES EAST.
THURSDAY AND THURSDAY NIGHT...THE LAST OF THIS ROUND OF UPPER LEVEL
SHORTWAVE ENERGY IMPULSES IS PROGGED TO MOVE EAST ACROSS THE STATE
THURSDAY BEFORE EXITING THE REGION THURSDAY AFTERNOON/NIGHT. UPPER
LEVEL RIDGING QUICKLY REBOUNDS ON THURSDAY NIGHT.
FRIDAY THROUGH MONDAY...THE MODELS IN GENERAL KEEP THE UPPER LEVEL
RIDGE ESTABLISHED OVER THE CENTRAL US THROUGH THE WEEKEND. THE
MODELS DIFFER AFTER THIS...WITH THE ECMWF KEEPING THE RIDGE IN PLACE
WHILE THE GFS SOLUTION DEPICTS THE RIDGE BROADENING AND MOVING EAST.
THUS WILL CONTINUE WITH A MODEL BLEND HERE WHICH GIVES MAINLY SLIGHT
CHANCE POPS EACH DAY.
TEMPERATURES SHOULD REMAIN ABOVE AVERAGE THROUGH SATURDAY WITH HIGHS
MAINLY 85-90 NORTH TO LOW TO MID 90S SOUTH. THE MODEL BLEND HINTS OF
TEMPERATURES MOVING BACK TOWARDS SEASONABLE SUNDAY/MONDAY WITH HIGHS
75-85 NORTH AND IN THE 80S SOUTH.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 600 PM CDT CDT MON AUG 26 2013
ISOLATED TO SCATTERED STRONG TO SEVERE THUNDERSTORMS ACROSS
WESTERN AND SOUTHERN NORTH DAKOTA WILL MOVE EAST THROUGH THE
EVENING. AREAS OF IFR FOG ARE ALSO POSSIBLE TONIGHT GIVEN LIGHT
WINDS AND THE HIGH HUMIDITY IN PLACE. WILL MONITOR RADAR TRENDS TO
AMEND TAFS FOR THUNDERSTORM IMPACTS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...WAA
LONG TERM...JV
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
334 PM CDT MON AUG 26 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 334 PM CDT MON AUG 26 2013
FORECAST CONCERNS ARE SEVERE THUNDERSTORMS THIS EVENING INTO THE
OVERNIGHT HOURS OVER NORTH CENTRAL WISCONSIN...WITH THE POTENTIAL
FOR DAMAGING WINDS...HEAVY RAINFALL...AND POSSIBLY LARGE HAIL.
ADDITIONAL CONCERNS ARE ON HEAT INDICES THROUGH TUESDAY.
LATEST SURFACE OBSERVATIONS PLACED A WARM FRONT EXTENDING FROM NEAR
MOORHEAD MINNESOTA THEN EXTENDING EAST...JUST NORTH OF THE
INTERSTATE 94 CORRIDOR...THEN RUNNING EAST TO JUST ALONG THE
WISCONSIN HIGHWAY 64 CORRIDOR. WATER VAPOR IMAGERY SHOWED A
SHORTWAVE MOVING EAST ACROSS EAST NORTH DAKOTA AND HEADING INTO
WESTERN MINNESOTA.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE WARM
FRONT THIS EVENING...FIRST OVER WEST CENTRAL MINNESOTA AS THE
SHORTWAVE INTERACTS WITH THE WARM FROM...THEN SPREADING EASTWARD
ALONG THE FRONT THIS EVENING AS THE WAVE PROGRESSES EAST. A VERY
MOIST AIRMASS IN PLACE OVER THE REGION WITH PRECIPITABLE WATER
VALUES RANGING FROM 1.8 TO 2.3...WHICH IS AROUND 200 PERCENT OF
NORMAL. ALSO...WARM CLOUD DEPTHS INCREASE TO 4.5 KM THIS EVENING. IN
ADDITION...850MB MOISTURE TRANSPORT INCREASES INTO THE FRONT THIS
EVENING. THESE FACTORS WILL LEAD TO THE POTENTIAL FOR HEAVY RAINFALL
WHICH COULD PRODUCE FLASH FLOODING. LOCATIONS OVER TAYLOR
COUNTY....ROUGHLY ALONG A LINE EXTENDING FROM JUMP RIVER...TO
MEDFORD...TO GAD...SAW RAINFALL AMOUNTS OF 2 TO ALMOST 3 INCHES
EARLY THIS MORNING. GIVEN THESE RAINFALL AMOUNTS PRECONDITIONING
THESE AREAS...WILL CONTINUE THE FLASH FLOOD WATCH FOR TAYLOR COUNTY
FROM 00Z THIS EVENING THROUGH 12Z TUESDAY MORNING. 0-6 KM BULK SHEAR
VALUES INCREASE TO 30 TO 35 KTS NORTH OF INTERSTATE 90 THIS EVENING
THEN INCREASE FURTHER TO AROUND 45 KTS LATE TONIGHT AS THE SHORTWAVE
MOVES INTO NORTHERN MINNESOTA AND NORTHERN WISCONSIN. THINKING
INITIALLY THE PRIMARY HAZARDS THIS EVENING OVER NORTH CENTRAL
WISCONSIN WILL BE HEAVY RAINFALL AND DAMAGING WINDS. SUPERCELLS LOOK
TO INITIATE OVER SOUTHEAST NORTH DAKOTA LATE THIS AFTERNOON INTO
EARLY THIS EVENING THEN RACE EAST ACROSS NORTH CENTRAL
MINNESOTA...FORMING INTO BOWING STRUCTURES WITH DAMAGING WINDS. THIS
ACTIVITY COULD BUILD SOUTH AS IT APPROACHES WEST CENTRAL
WISCONSIN...POSSIBLY GETTING INTO THE FORECAST AREA AFTER MIDNIGHT.
THINKING MOST OF THIS ACTIVITY SHOULD REMAIN NORTH OF INTERSTATE
90...AND POSSIBLY NORTH OF THE INTERSTATE 94 CORRIDOR. ANOTHER HOT
AND MUGGY DAY IS IN STORE FOR THE AREA ON TUESDAY...BUT IT IS
UNCLEAR HOW FAR SOUTH OUT FLOW BOUNDARIES WOULD GET FROM OVERNIGHT
CONVECTION WHICH WILL HAVE AN IMPACT ON HIGH TEMPERATURES TOMORROW.
IT APPEARS MUCH OF THE FORECAST AREA WILL REMAIN IN THE WARM
SECTOR...WITH HOT SOUTHERLY FLOW PERSISTING UNTIL A WEAK COLD FRONT
MOVES THROUGH LATE IN THE AFTERNOON INTO THE EVENING HOURS. THERE
ISN/T MUCH CONVERGENCE ALONG THE FRONT SO NOT ANTICIPATING
THUNDERSTORM DEVELOPMENT BUT WILL HAVE TO KEEP A CLOSE EYE ON IT.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 334 PM CDT MON AUG 26 2013
HIGH PRESSURE SETTLES INTO THE AREA TUESDAY NIGHT THROUGH EARLY
THURSDAY MORNING PROVIDING SOME RELIEF FROM THE HEAT. HIGHS ON
THURSDAY WILL STILL BE ON THE UNCOMFORTABLE SIDE...CLIMBING INTO
THE UPPER 80S TO LOWER 90S. DEWPOINTS ALSO GRADUALLY FALL WEDNESDAY
AFTERNOON INTO WEDNESDAY EVENING AS NORTHEASTERLY FLOW USHERS IN
SLIGHTLY DRIER AIR. HEAT INDEX VALUES ARE EXPECTED TO CLIMB INTO THE
UPPER 80S TO LOWER 90S ON WEDNESDAY. THE HIGH SHIFTS EAST ON
THURSDAY AS A WARM FRONT PUSHES EAST OUT OF THE NORTHERN PLAINS INTO
THE UPPER MISSISSIPPI RIVER VALLEY. THE FRONT WILL BRING A CHANCE OF
SHOWERS AND THUNDERSTORMS TO THE FORECAST AREA AS IT MOVES THROUGH
THURSDAY INTO THURSDAY NIGHT. THE FRONT THEN STALLS OVER THE REGION
FRIDAY INTO THE WEEKEND AND INTERACTS WITH WEAK SHORTWAVES AS UPPER
RIDGING PUSHES EAST OUT OF THE NORTHERN PLAINS. THERE REMAINS
CONSIDERABLE UNCERTAINTY ON TEMPERATURES THIS WEEKEND THROUGH LABOR
DAY. THE GFS IS SHOWING WARM SOUTHERLY FLOW...WITH HIGHS CLIMBING
WELL INTO THE 90S. ON THE OTHER HAND THE ECMWF SHOWS A TROUGH OVER
THE REGION WITH HIGHS ONLY IN THE 80S ON SATURDAY...THEN FALLING
INTO MID 70S TO LOWER 80S ON SUNDAY. THE GFS WOULD KEEP US IN THE
90S ON SUNDAY...THEN A COLD FRONT FINALLY SLIDES THROUGH ON MONDAY
AND COOLS HIGHS. FRIDAY LOOKS TO BE THE WARMEST DAY...WITH POSSIBLY
HEAT HEADLINES NEEDED AGAIN ALONG AND WEST OF THE MISSISSIPPI RIVER.
WILL HAVE TO KEEP A VERY CLOSE WATCH ON MODEL TRENDS OVER THE NEXT
FEW DAYS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1215 PM CDT MON AUG 26 2013
WITH A SFC FRONT EXPECTED TO STAY NORTH OF KRST/KLSE THROUGH
TONIGHT/WED...THE ENVIRONMENT WILL STAY CAPPED...KEEPING SHRA/TS
TO THE NORTH. VFR CONDITIONS ARE EXPECTED THROUGH WED. COULD SEE
SOME MID/HIGH LEVEL CLOUDS FROM TIME TO TIME...ESPECIALLY LATE
OVERNIGHT/EARLY WED.
FOR WINDS...SOME POTENTIAL FOR HIGHER GUSTS THIS AFTERNOON...BUT NOT
AS MUCH AS PREVIOUS DAYS. SOME CONCERN FOR LLWS AT KLSE/KRST TONIGHT
AS NAM BUFKIT SOUNDINGS SUGGEST WINDS INCREASE TO 40+ KTS BY 1500
FT. GFS AND RAP ARE NOT AS BULLISH THOUGH...ABOUT 10 KTS LESS.
WITHOUT MORE CONSENSUS...CONFIDENCE IS LOWER. WILL KEEP OUT OF THE
TAF FOR NOW...BUT THE POTENTIAL WILL HAVE TO BE MONITORED.
&&
.HYDROLOGY...THROUGH TUESDAY MORNING
ISSUED AT 334 PM CDT MON AUG 26 2013
HEAVY RAIN FELL ACROSS TAYLOR COUNTY EARLY MONDAY
MORNING PRODUCING 2 TO NEARLY 3 INCHES OF RAINFALL. THUNDERSTORMS
ARE POSSIBLE ACROSS THESE SAME AREAS TONIGHT INTO TUESDAY MORNING
AND THEY WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL WITH
PRECIPITABLE WATER VALUES OF 1.8 TO 2.3 INCHES AND WARM CLOUD
DEPTHS OF 4.5 KM. ALSO...850 MOISTURE TRANSPORT FOCUSES INTO A
WARM FRONT LOCATED OVER NORTH CENTRAL WISCONSIN WHICH COULD RESULT
IN REPEATED ROUNDS OF SHOWERS AND THUNDERSTORMS DURING THE
OVERNIGHT HOURS. A FLASH FLOOD WATCH IS IN EFFECT FOR TAYLOR COUNTY
FROM 7PM THIS EVENING THROUGH 7AM TUESDAY.
&&
.CLIMATE...
ISSUED AT 334 PM CDT MON AUG 26 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
034-042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ032-033-041.
FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH TUESDAY
MORNING FOR WIZ017.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ086-087-
094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-088-096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION.....RIECK
HYDROLOGY...WETENKAMP
CLIMATE...WETENKAMP
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 245 PM CDT MON AUG 26 2013
MESO ANALYSIS PAGE INDICATED CAPES OF 2000/3000 J/KG AND SURFACE
BASED CONVECTIVE INHIBITION LESS THAN 50 J/KG ACROSS
NORTH-CENTRAL WISCONSIN. THERE IS A DIFFERENTIAL HEATING
BOUNDARY SET UP ACROSS NORTH CENTRAL INTO NORTHEAST WISCONSIN
THIS AFTERNOON THAT MAY BE A FOCUS FOR CONVECTION LATE THIS
AFTERNOON AND THIS EVENING. TEMPERATURES WERE IN THE LOWER TO
MIDDLE 80S ACROSS THE NORTH AND IN THE LOWER TO MIDDLE 90S SOUTH
OF THE BOUNDARY.
TRYING TO TIME CONVECTIVE COMPLEX TONIGHT AND TUESDAY WILL BE THE
MAIN PROBLEM. SINCE THE HRRR MESOSCALE MODEL DID WELL OVERNIGHT
AND THIS MORNING...WILL FOLLOW THIS MODEL FOR CONVECTIVE TRENDS
TONIGHT INTO TUESDAY MORNING. THE HRRR MODEL INDICATED A CLUSTER
OF SHOWERS AND STORMS WOULD DEVELOP AND MOVE ACROSS THE AREA
LATER THIS AFTERNOON THROUGH MID EVENING...THEN A BREAK IN THE
ACTION UNTIL CONVECTIVE COMPLEX MOVES ACROSS THE AREA AFTER
MIDNIGHT THROUGH MID TUESDAY MORNING. LATEST REGIONAL RADARS INDICATED
CONVECTION WAS TRYING TO FIRE ACROSS WESTERN WISCONSIN AT 1945Z.
AFTER THE CONVECTIVE COMPLEX EXITS THE AREA BY LATE TUESDAY
MORNING...BOUNDARY LURKING NEARBY. STILL SOME UNCERTAINTY
ON HOW CONVECTION WILL EVOLVE TOMORROW AFTERNOON AFTER THE
MORNING CONVECTION. PLENTY OF HEAT AND HUMIDITY AVAILABLE
FOR STRONG OR SEVERE STORMS LATER TOMORROW AFTERNOON. HIGHS
WILL RANGE FROM THE MIDDLE 80S NORTH TO THE LOWER TO MIDDLE 90S
SOUTH.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 245 PM CDT MON AUG 26 2013
TEMPERATURES AND PCPN TRENDS ARE THE PRIMARY FCST CONCERNS.
THE COLD FRONT AND WEAK S/W TROF SHOULD GENERATE SCT STG/SVR TSTMS
OVER OUR SE COUNTIES ON TUESDAY EVG...FOLLOWED BY DRY CONDITIONS
FOR THE OVERNIGHT HOURS.
HIGH PRESSURE WILL BRING DRIER AND A LITTLE COOLER WEATHER TO THE
REGION WEDS INTO THU MORNING...BUT RETURN FLOW ON THE NW PERIPHERY
OF THE HIGH MAY BRING PCPN BACK INTO OUR NW COUNTIES BY THURSDAY
AFTERNOON. A WARM AND FAIRLY HUMID AIR MASS SHOULD RETURN TO
THE FORECAST AREA INTO THE WEEKEND...UNTIL A COLD FRONT MOVES
THROUGH ON SUNDAY OR SUNDAY NIGHT. SO...SMALL PCPN CHANCES WILL
CONTINUE DURING THE PERIOD.
MODELS HAVE A BIG DISPARITY IN H8 TEMPS NEXT MONDAY...WITH THE
ECMWF SHOWING A MUCH MORE AMPLIFIED UPPER LEVEL PATTERN AND
MUCH COOLER TEMPS THAN THE GFS/GEFS. NOTICE THAT THE 12Z ECMWF
WAS NOT QUITE AS COLD AS THE PREV RUN...AND IS CLOSER TO THE
ECMWF ENSEMBLE MEAN...SO A COMPROMISE IS IN ORDER. HAVE GONE
WITH SOME MODEST COOLING ON MONDAY...BUT NOTHING AS DRASTIC
AS THE ECMWF SHOWS.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 245 PM CDT MON AUG 26 2013
TRYING TO TIME CONVECTIVE COMPLEXES TONIGHT THROUGH TUESDAY WILL
BE THE MAIN CONCERN. 18Z TAFS TRIED TO DEPICT THE MOST LIKELY
TIMES OF SHOWERS AND STORMS AT THE TAF SITES...BUT SOME ADJUSTMENT
IN TIMING WILL BE NEEDED AS WE GET CLOSER TO THE EVENT. FOLLOWED
THE HRRR MESOSCALE MODEL SINCE IT DID WELL OVERNIGHT AND THIS MORNING.
THIS MODEL IS DEPICTING SCATTERED CONVECTION MOVING OR DEVELOPING
ACROSS THE AREA LATER THIS AFTERNOON INTO MID EVENING...WITH A BREAK
IN THE ACTION FOR AWHILE UNTIL NEXT COMPLEX MOVES ACROSS THE AREA
AFTER MIDNIGHT THROUGH MID MORNING ON TUESDAY. GUSTY WINDS CAN BE
EXPECTED WITH THE STORMS WITH SOME GUSTS OVER 40 KNOTS AND POSSIBLY
50 KNOTS ARE POSSIBLE. A GREAT DEAL OF UNCERTAINTY EXISTS TUESDAY
AFTERNOON WITH BOUNDARY LURKING NEARBY WITH RESPECT TO WIND DIRECTION
AND POSSIBLE SHOWER AND THUNDERSTORM ACTIVITY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....ECKBERG
LONG TERM......KIECKBUSCH
AVIATION.......ECKBERG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1215 PM CDT MON AUG 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 309 AM CDT MON AUG 26 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER
THE PACIFIC NORTHWEST AND EASTERN PACIFIC...AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUES TO STREAM OUT OF BAJA CALIFORNIA...UP THROUGH THE DAKOTAS
AND INTO THE NORTHERN GREAT LAKES AROUND THE SUBTROPICAL RIDGE. ONE
SUCH SHORTWAVE COMBINED WITH 700MB MOISTURE TRANSPORT SUPPORTING
CONVECTION TRACKING ACROSS FAR NORTHERN WI AND UPPER MICHIGAN.
REGARDING MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED
VALUES OF 1.5-2 INCHES FROM EASTERN SOUTH DAKOTA INTO THE NORTHERN
GREAT LAKES. AIRMASS IS ALSO VERY WARM WITH 850MB TEMPS FROM 00Z
RAOBS OF 22-24C ACROSS THE FORECAST AREA AND 24-28C OVER THE
NORTHERN PLAINS. WITH THE FORECAST AREA IN THE WARM SECTOR...SOUTH
OF A WARM FRONT POSITIONED OVER FAR NORTHERN WI...A SOUTHERLY BREEZE
HAS ONLY ALLOWED TEMPS TO FALL INTO THE MID TO UPPER 70S. THIS SAME
SOUTHERLY BREEZE HAS ADVECTED IN SOME LOWER DEWPOINTS...WHICH HAVE
FALLEN INTO THE 60S...LOWEST IN THE SOUTHEAST HALF OF THE AREA. 00Z
DVN SOUNDING REALLY SHOWED THE DRIER AIR COMPARED TO MPX.
..MODEL VERIFICATION..
HAVE INCLUDED THIS SECTION AS IT HAS HIGH IMPORTANCE WITH THE
FORECAST OF HIGH TEMPERATURES AND CONVECTION. LOOKING AT 00Z RAOBS
FOR 925MB TEMPS AND COMPARING TO 25.00Z MODEL GUIDANCE...THE ECMWF
WAS THE BEST WITH ALMOST NO ERROR ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST. THE GFS WAS GENERALLY 1-2C TOO HIGH. LASTLY...THE
NAM/RAP WERE THE WORST...HAVING ERRORS ON THE ORDER OF 3-6C...
HIGHEST AT MSP. BECAUSE THE NAM/RAP WERE TOO HIGH...IT BROKE THE CAP
AND BROUGHT THE CONVECTION WAY TOO FAR SOUTH.
..HAZARDS..
1. HEAT. TEMPERATURES ARE LIKELY TO BE A FEW DEGREES HIGHER TODAY
AND WITH DEWPOINTS CLIMBING BACK INTO THE LOW 70S...HEAT INDICES
SHOULD TOP OUT IN THE 100-105 RANGE. THE HIGHEST HEAT INDICES LOOK
TO OCCUR FROM LAKE CITY DOWN TO LA CROSSE...AND HAVE UPGRADED THIS
AREA TO AN EXCESSIVE HEAT WARNING.
2. STORMS. SOME SEVERE POTENTIAL AFTER MIDNIGHT TONIGHT...MAINLY
ACROSS TAYLOR/CLARK COUNTIES. HAVE TO WATCH RAINFALL AMOUNTS TOO.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE SUGGESTS THE SUBTROPICAL RIDGING RETROGRADES
JUST SLIGHTLY WESTWARD DURING THE NEXT 24 HOURS. THE MAIN FEATURE OF
FOCUS IS A STRETCHED OUT SHORTWAVE IN THE MONSOONAL FLOW...LOCATED
FROM EASTERN UTAH INTO SOUTH CENTRAL WYOMING. MODELS BRING THIS
SHORTWAVE INTO THE DAKOTAS BY 00Z AND PERHAPS AS FAR EAST AS WESTERN
UPPER MI BY 12Z. THIS SHORTWAVE HELPS TO LIFT A SURFACE LOW SITTING
NEAR THE BLACK HILLS OF SOUTH DAKOTA TO NEAR MINNEAPOLIS BY 12Z TUE.
..DETAILS..
FOCUS FOR POTENTIAL CONVECTION TODAY WILL LIE ON THE LOCATION OF THE
WARM FRONT IN NORTHERN WI. FIRST OFF...THE CURRENT CONVECTION
CROSSING FAR NORTHERN WI AND UPPER MI COULD DROP INTO TAYLOR AND
POSSIBLY CLARK COUNTY BEFORE WEAKENING THIS MORNING. THE OUTFLOW
FROM THE CONVECTION SHOULD HELP PUSH THE FRONT SOUTH TOWARDS I-94
THIS AFTERNOON. THEN...THE NEXT QUESTION IS IF THE AIRMASS IS
CAPPED...WHICH ENTIRELY DEPENDS ON HOW WARM WE GET. THERE SHOULD BE
PLENTY OF SUN TODAY ACROSS THE FORECAST AREA WITH MAYBE A FEW STRAY
CIRRUS CLOUDS. ECMWF 925MB TEMPS ARE PROGGED ABOUT 1-2C HIGHER
COMPARED TO YESTERDAY...THUS ANTICIPATING HIGHS TO BE ABOUT 1-3F
HIGHER... YIELDING READINGS MAINLY IN THE LOW TO MID 90S. A FEW
SPOTS LIKE LSE COULD EVEN HIT THE UPPER 90S. ECMWF ALSO DID VERY
WELL WITH THE DEWPOINTS YESTERDAY AND SUGGESTS THEY SHOULD CLIMB
INTO THE LOW 70S IN THE AFTERNOON...DUE TO EVAPOTRANSPORATION AND
THE HIGHER MOISTURE TO OUR NORTHWEST SLIDING SOUTH. THE FORECAST
HIGHS AND DEWPOINTS WOULD SEEM TO POINT TO POTENTIAL FOR THE CAP TO
BREAK...THUS HAVE INCLUDED 20-40 PERCENT CHANCES ON THE WARM FRONT
FOR THE AFTERNOON. SHOULD STORMS DEVELOP...0-6KM SHEAR IS ONLY 25 KT
AT BEST WITH 0-3KM NEAR 20KT. THIS MEANS THE STORMS WILL PROBABLY BE
UNORGANIZED AND MOST LIKELY JUST HEAVY RAIN MAKERS GIVEN HIGH CAPE
AND NEAR 2 INCH PRECIPITABLE WATERS.
TONIGHT IS A BIT MORE INTERESTING. A CONVECTIVE COMPLEX APPEARS
LIKELY TO DEVELOP IN THE GRAND FORKS AREA IN THE EVENING AHEAD OF
THE SHORTWAVE. THIS CONVECTION...AIDED ALSO BY 700MB MOISTURE
TRANSPORT LIKE THE CONVECTION GOING OVER UPPER MI...SHOULD TRACK
EAST-SOUTHEAST INTO NORTHERN WI. THIS MEANS TAYLOR/CLARK COULD BE
IMPACTED BY THE COMPLEX AFTER MIDNIGHT. ADDITIONAL CONVECTION COULD
FORM ON THE NOSE OF 850MB MOISTURE TRANSPORT NORTH OF I-94 THIS
EVENING AS WELL. CANNOT RULE OUT SOME SEVERE WEATHER...LIKELY IN THE
FORM OF DAMAGING WINDS AND LARGE HAIL...ESPECIALLY AFTER MIDNIGHT
WHEN 0-6 KM SHEAR VALUES APPROACH 30-40 KT. THE REST OF THE AREA
SHOULD STAY MAINLY DRY...CAPPED AND WARM WITH A SOUTHERLY BREEZE
PERSISTING. LOW TEMPERATURES ARE LIKELY TO BE SIMILAR TO NOW GIVEN
SIMILAR CONDITIONS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 309 AM CDT MON AUG 26 2013
..HAZARDS..
1. HEAT...WHICH WILL PERSIST INTO TUESDAY. COLD FRONT COMES THROUGH
TUESDAY NIGHT WHICH SHOULD HELP ADVECT BOTH SOMEWHAT COOLER AND MORE
IMPORTANTLY DRIER AIR INTO THE AREA FOR WEDNESDAY. HEAT LOOKS TO
RETURN DURING LABOR DAY WEEKEND.
2. STORMS. THOSE ON TUESDAY COULD POSE A SEVERE AND HEAVY RAIN
THREAT NORTH OF I-94.
..SYNOPTIC OVERVIEW..
26.00Z MODEL GUIDANCE CONTINUES TO SUGGEST THAT THE SUBTROPICAL HIGH
WILL RETROGRADE WESTWARD THROUGH THE WEEK...ENDING UP IN COLORADO ON
FRIDAY. THIS RETROGRESSION IS IN RESPONSE TO A SERIES OF SHORTWAVE
TROUGHS DROPPING INTO THE MID-ATLANTIC REGION ON THE EAST SIDE OF
THE RIDGE. AS WE HEAD INTO THE WEEKEND...THE SUBTROPICAL RIDGE WILL
SHIFT EAST IN RESPONSE TO WHAT LOOKS TO BE A VERY DEEP TROUGH FOR
THIS TIME OF YEAR COMING INTO THE PACIFIC NORTHWEST. IT SHOULD BE
NOTED THAT THE 26.00Z ECMWF THROWS A MAJOR CURVE BALL TO THE WEEKEND
PLAN...DEVIATING GREATLY FROM ITS PREVIOUS RUN IN SHOWING A TROUGH
DIGGING INTO THE WESTERN GREAT LAKES LATE SUNDAY. THE REASON IS
RELATED TO THIS TROUGH BEING STRONGER AND TRACKING FARTHER SOUTH
COMING OUT OF SOUTHWEST CANADA ON FRIDAY...COMPARED TO ITS PREVIOUS
RUN...THE 26.00Z GFS AND CANADIAN. NOT READY TO FULLY BUY INTO THE
26.00Z ECMWF QUITE YET BEFORE SEEING THE ECMWF ENSEMBLES AND ITS
NEXT RUN.
..DETAILS..
THE SURFACE OVER CENTRAL MN AT 12Z TUESDAY WILL GRADUALLY DROP
SOUTHEAST THROUGH TUESDAY AND TUESDAY NIGHT...IN RESPONSE TO THE
SHORTWAVE AND CONVECTION OVER NORTHERN WI/UPPER MI DROPPING
SOUTHEAST. HAVE KEPT SOME CHANCES ON TUESDAY NORTHEAST OF I-94 FOR
THE CONVECTION DROPPING SOUTHEAST...WHICH COULD BE SEVERE AS WELL.
THE REST OF THE AREA LOOKS CAPPED. TALKING ABOUT THE CAPPING...925MB
TEMPS ARE PROGGED TO REACH ABOUT 28C ON I-94 TO 30C IN NORTHEAST
IOWA. THESE READINGS SHOULD YIELD HIGHS RANGING FROM THE LOW TO
UPPER 90S...WARMEST IN RIVER VALLEYS. THE EXCESSIVE HEAT WARNING MAY
NEED EXPANSION INTO SOME OF NORTHEAST IOWA AND FAR SOUTHWEST WI IF
TEMP/DEWPOINT TRENDS CONTINUE. ALL CONVECTION LOOKS LIKE IT WILL BE
SOUTHEAST OF THE AREA FOR TUESDAY NIGHT...THUS WENT DRY THEN.
DRY CONDITIONS ARE EXPECTED FOR WEDNESDAY AND WEDNESDAY NIGHT AS
HIGH PRESSURE BUILDS OVER WISCONSIN AND MICHIGAN IN THE WAKE OF
TUESDAYS LOW AND COLD FRONTAL PASSAGE. 925MB TEMPS OF 24-26C STILL
SUPPORTS HIGHS IN THE MID 80S TO LOW 90S...THOUGH. DEWPOINTS MAY
STILL BE UP IN THE LOW 70S OVER NORTHEAST IOWA...BUT HEAT INDICES
ARE MORE AROUND 95 VERSUS THE 100-105 AS OF LATE.
THURSDAY THROUGH SATURDAY FEATURE A GRADUAL WARM ADVECTION
PATTERN...WHICH MEANS A RETURN FOR SOME CHANCES OF SHOWERS AND
THUNDERSTORMS. HIGHEST CHANCES ARE FORECAST THURSDAY NIGHT OVER
WISCONSIN WHERE THERE APPEARS TO BE A JUXTAPOSITION OF RIGHT
ENTRANCE REGION FORCING...A POSSIBLE SHORTWAVE MOVING THROUGH...AND
THE LOW LEVEL MOISTURE TRANSPORT. SOME OF THESE CHANCES OF SHOWERS
AND THUNDERSTORMS MAY BE ABLE TO BE BETTER REFINED...IN TERMS OF
DRYING SOME OUT...OVER THE COMING DAYS AS MODELS SETTLE INTO THE
TIMING OF THE WARM ADVECTION. ONCE THE WARM AIR COMES IN...WE WILL
HAVE TO BE CONCERNED WITH HEAT ADVISORIES...AS EVEN THE NEW 26.00Z
ECMWF SHOWS 925MB TEMPS APPROACHING 30C OVER WESTERN PORTIONS OF THE
FORECAST AREA LATE FRIDAY.
SUNDAY AND THE REST OF LABOR DAY WEEKEND FORECAST IS NOW UP IN THE
AIR DUE TO THE NEW 26.00Z ECMWF. PREVIOUSLY AND IN AGREEMENT WITH
THE 26.00Z GFS IT APPEARED MUCH OF THE AREA WOULD BE IN THE WARM
SECTOR...WITH 925MB TEMPS OF 29-32C WHICH COULD ALLOW FOR HIGHS
AROUND 100. IF THE NEW ECMWF IS RIGHT...WE GET A MOSTLY DRY COLD
FRONTAL PASSAGE ON SUNDAY WITH HIGHS MORE IN THE MID TO UPPER 80S.
MONDAY ENDS UP MUCH MUCH COOLER WITH HIGHS MOSTLY IN THE 60S.
COMPARE THIS TO ITS PREVIOUS 4 RUNS SHOWING 94-98 AT LA CROSSE FOR
MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1215 PM CDT MON AUG 26 2013
WITH A SFC FRONT EXPECTED TO STAY NORTH OF KRST/KLSE THROUGH
TONIGHT/WED...THE ENVIRONMENT WILL STAY CAPPED...KEEPING SHRA/TS
TO THE NORTH. VFR CONDITIONS ARE EXPECTED THROUGH WED. COULD SEE
SOME MID/HIGH LEVEL CLOUDS FROM TIME TO TIME...ESPECIALLY LATE
OVERNIGHT/EARLY WED.
FOR WINDS...SOME POTENTIAL FOR HIGHER GUSTS THIS AFTERNOON...BUT NOT
AS MUCH AS PREVIOUS DAYS. SOME CONCERN FOR LLWS AT KLSE/KRST TONIGHT
AS NAM BUFKIT SOUNDINGS SUGGEST WINDS INCREASE TO 40+ KTS BY 1500
FT. GFS AND RAP ARE NOT AS BULLISH THOUGH...ABOUT 10 KTS LESS.
WITHOUT MORE CONSENSUS...CONFIDENCE IS LOWER. WILL KEEP OUT OF THE
TAF FOR NOW...BUT THE POTENTIAL WILL HAVE TO BE MONITORED.
&&
.CLIMATE...
ISSUED AT 346 PM CDT SUN AUG 25 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-
034-042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
WIZ032-033-041.
FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH TUESDAY
MORNING FOR WIZ017.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ086-087-
094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR
MNZ079-088-096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....RIECK
CLIMATE......WETENKAMP
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
321 PM MDT MON AUG 26 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 315 PM MDT MON AUG 26 2013
CURRENT KCYS RADAR LOOP SHOWS SHOWERS AND TSTORMS JUST STARTING TO
DEVELOP ALONG THE FRONT RANGE FOOTHILLS AND THE SOUTHERN LARAMIE
RANGE THIS AFTERNOON. BELIEVE MOST OF THE ACTIVITY WILL REMAIN
ALONG I80 AND NEAR THE COLORADO BORDER TODAY ACROSS SOUTHEAST
WYOMING. FURTHER TO THE EAST ACROSS WESTERN NEBRASKA...THE
THERMAL RIDGE AXIS CONTINUES TO REMAIN OVER THE AREA RESULTING IN
HOT TEMPERATURES IN THE MID TO UPPER 90S. DRY AIR ALOFT AND
MIDLEVEL SUBSIDENCE WILL LIMIT MOST CONVECTION POTENTIAL THROUGH
THE EVENING...ALTHOUGH A FEW ISOLATED TSTORMS MAY DEVELOP ALONG
THE CHEYENNE RIDGE TOWARDS KIMBALL AND SIDNEY. THE TSTORMS WILL
QUICKLY DIMINISH IN INTENSITY AFTER SUNSET THIS EVENING.
SUBTROPICAL MOISTURE PLUME WILL SHIFT A BIT FURTHER NORTH AND WEST
FOR TUESDAY...SO KEPT SCATTERED POP (25 TO 50 PERCENT) ALONG AND
WEST OF THE LARAMIE RANGE. ISOLATED TSTORMS ARE POSSIBLE FOR THE
HIGH PLAINS OF SOUTHEAST WYOMING...BUT THINK THE COVERAGE WILL BE
SPARSE AS SOME DRIER AIR ALOFT MOVES INTO SOUTHEAST WYOMING.
ANOTHER HOT DAY IS EXPECTED FOR WESTERN NEBRASKA AS HIGHS CLIMB
INTO THE UPPER 90S.
FOR WEDNESDAY...THE RIDGE AXIS EXTENDING NORTHEASTWARD FROM THE
MAIN UPPER LEVEL HIGH WILL PUSH ACROSS THE AREA. ALTHOUGH THE GFS
IS MORE AGGRESSIVE WITH DEVELOPING AFTERNOON TSTORMS NEAR THE WEST
OF THE LARAMIE...BELIEVE THE DRY AIR AND SUBSIDENCE ALOFT WILL
GREATLY REDUCE COVERAGE OF THESE TSTORMS. KEPT POP BETWEEN 15 TO
25 PERCENT FOR THE LOWER ELEVATIONS AND UP TO 40 PERCENT FOR THE
MOUNTAINS. HOT TEMPERATURES WILL CONTINUE AND SPREAD WESTWARD INTO
SOUTHEAST WYOMING ON WEDNESDAY WITH HIGHS IN THE LOW TO MID 90S
POSSIBLE EAST OF A LINE FROM CHEYENNE TO DOUGLAS...WITH
TEMPERATURES NEAR 100 ACROSS THE LOWER ELEVATIONS OF WESTERN
NEBRASKA.
.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 330 PM MDT MON AUG 26 2013
BROKEN RECORD CONTINUES WITH AFTERNOON SHOWERS AND THUNDERSTORMS.
REALLY SOMETHING WRONG WITH THE LATEST ECMWF RUN AS IT IS SHOWING
COPIOUS AMOUNTS OF QPF THROUGH THE EXTENDED. HAVE DISCOUNTED ITS
SOLUTION FOR THE EXTENDED.
FOR THURSDAY...LOOKS PRETTY HOT WITH 700MB TEMPERATURES OF +16 TO
+18C. LOOKING AT MID TO UPPER 90S IN THE PANHANDLE AND MID 80S OUT
WEST. WINDS FAIRLY LIGHT...700MB WINDS UNDER 10KTS.
EVEN WARMER TEMPERATURES EXPECTED FRIDAY AS 700MB TEMPERATURES
CLIMB TO +18C ACROSS THE CWFA. COULD SEE HIGHS NEAR 100 OUT IN THE
PANHANDLE WITH 90S COMMON IN SOUTHEAST WYOMING. WENT SLIGHTLY OVER
THE BCALLBLEND GUIDANCE FOR TEMPERATURES...ESPECIALLY OUT IN THE
PANHANDLE. ITS OUTPUT JUST LOOKS WAY TOO LOW.
FOR THE WEEKEND...WE HAVE A WAVE MOVING UP NORTH FROM
TEXAS...WHICH IS MOST LIKELY SUBTROPICAL IN NATURE...THAT MAKES IT
INTO NORTHEASTERN COLORADO. COULD SEE A MORE WIDESPREAD RAIN
SHOWER EVENT AS THIS OCCURS. GIVEN THE PROBLEMS WITH THE ECMWF
THOUGH...STILL WENT UNDER GUIDANCE ON POPS...AND THEREFORE THE
EXTENDED PROCEDURE OUTPUT. WILL ADJUST AS THE EVENT DRAWS CLOSER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY MORNING)
ISSUED AT 1059 AM MDT MON AUG 26 2013
DO BELIEVE THUNDERSTORM CHANCES WILL BE MAINLY CONFINED TO THE
SOUTHERN LARAMIE RANGE AS WELL AS THE KLAR AND KCYS AERODROMES
THIS AFTERNOON. LATEST HRRR COMPOSITE REFLECTIVITY FORECAST
SHOWING THIS AREA THE PRIME AREA TODAY. SO...WENT AHEAD AND ADDED
TEMPO THUNDERSTORMS IN THE KLAR AND KCYS TAFS. VFR OTHERWISE WITH
CONVECTION ENDING SHORTLY AFTER 00Z.
&&
.FIRE WEATHER...
ISSUED AT 210 PM MDT MON AUG 26 2013
NO FIRE WEATHER CONCERNS THROUGH THE WEEK WITH DAYTIME HUMIDITIES
REMAINING ABOVE 20 PERCENT...AND GENERALLY BETWEEN 20 TO 35
PERCENT ACROSS THE WHOLE FORECAST AREA...WITH GREAT OVERNIGHT
RECOVERIES. NOT MUCH OF A PATTERN CHANGE ANTICIPATED OVER THE NEXT
7 DAYS AS A STUBBORN UPPER LEVEL HIGH WILL REMAIN NEARLY
STATIONARY BETWEEN THE CENTRAL ROCKIES AND CENTRAL GREAT PLAINS.
VERY WARM TEMPERATURES ARE EXPECTED TO CONTINUE THROUGH THE WEEK
AND EVEN INTO NEXT WEEKEND. DUE TO THE LOCATION OF THE UPPER LEVEL
HIGH THE JET STREAM WILL REMAIN WELL TO THE NORTH...SO LIGHT WINDS
WILL PREVAIL ACROSS THE AREA.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...TJT
LONG TERM...CLAYCOMB
AVIATION...CLAYCOMB
FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1103 AM MDT MON AUG 26 2013
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 500 AM MDT MON AUG 26 2013
WATER VAPOR IMAGERY SHOWS THE STRONG UPPER RIDGE OVER THE CENTRAL
CONUS...WITH MOIST SUBTROPICAL FLOW MOVING UP FROM THE SOUTHWEST
AND OVER THE FORECAST AREA. LOOKS LIKE THE MAIN IVO ENERGY CENTER
IS STILL OVER BAJA...BUT ITS MOISTURE PLUME IS GETTING CAUGHT IN
THE UPPER JET AND IS MOVING ON UP AND INTO THE GREAT BASIN. THIS
WILL CONTRIBUTE TO THUNDERSTORM CHANCES FOR THE CWA TODAY.
WILL SEE ANOTHER ROUND OF HOT TEMPS FOR EASTERN PORTIONS OF THE
FORECAST AREA TODAY WHERE THE THERMAL RIDGE AXIS IS IN PLACE.
FURTHER WEST...WILL SEE GUSTY WEST TO SOUTHWEST WINDS ACROSS
SOUTHEAST WYOMING WHERE 700 MB WINDS WILL REMAIN BETWEEN 30 AND 35
KT THROUGH THIS AFTERNOON. THESE STRONGER WINDS WILL ADD AN
UPSLOPE COMPONENT TO THE WESTERN SLOPES...AND ALONG WITH WEAK
INSTABILITY PROGGED BY THE MODELS...LIKELY TO SEE A PRETTY GOOD
CHANCE FOR SHOWERS AND THUNDERSTORMS IN THIS AREA THROUGH THE
AFTERNOON. PWATS AROUND 150 PERCENT OF NORMAL WILL INCREASE THE
LIKELIHOOD FOR MODERATE TO HEAVY RAIN TO OCCUR OUT OF THIS
ACTIVITY AS WELL. A FEW STORMS LOOK TO DEVELOP ALONG THE CHEYENNE
RIDGE WHERE A SFC BOUNDARY LOOKS TO SET UP THROUGH THE EARLY
AFTERNOON LIKELY DUE TO DIFFERENTIAL HEATING ALONG THIS TERRAIN
FEATURE. FURTHER EAST AND NORTH ACROSS THE REMAINING PLAINS AREAS
OF SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE...CHANCES FOR
CONVECTION WILL BE LESS WITH ONLY A FEW ISOLATED STORMS EXPECTED
TO MAKE IT OFF THE HIGHER TERRAIN.
THE DEEPER MONSOONAL MOISTURE WILL SHIFT WESTWARD FOR TUESDAY
HOWEVER THE MOUNTAINS WILL REMAIN ON THE EASTERN PERIPHERY OF THIS
PLUME. THEREFORE WILL STILL SEE CHANCES FOR AFTERNOON AND EVENING
THUNDERSTORMS WITH SLIGHTLY MORE INSTABILITY PROGGED IN THIS AREA
AS WELL. A WEAK SURFACE TROUGH LOOKS TO SET UP ALONG EAST CENTRAL
WYOMING...SO WILL HAVE TO BE MINDFUL OF INITIATION OF WEAK
CONVECTION HERE AS WELL...BUT ACTIVITY WILL REMAIN ISOLATED.
OTHERWISE...TUESDAY WILL BE ANOTHER HOT DAY FOR MUCH OF THE REGION
BUT WITH LESS WIND.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM MDT MON AUG 26 2013
THE 00Z NWP GUIDANCE SHOWS THE LARGE SCALE UPPER RIDGE AXIS
RETROGRADING WEST FROM THE GREAT PLAINS TOWARD THE FRONT RANGE BY
THE END OF THE WEEK AS A TROUGH DIGS SOUTH OVER THE NORTHEAST
CONUS. A WEAK UPPER LOW IS PROGGED TO MOVE FROM THE UPPER TX COAST
ACROSS WEST CENTRAL TX AND INTO THE CENTRAL PLAINS EARLY IN THE
PERIOD. THIS FEATURE WILL SERVE TO ENTRAIN SOME DRIER AIR INTO
SOUTHEAST WY AND NEB PANHANDLE. MODEL DIFFERENCES BECOME APPARENT
THIS WEEKEND AS THE ECMWF BUILDS THE UPPER RIDGE NORTHWEST INTO
BRITISH COLUMBIA WITH AN EASTERN PACIFIC UPPER LOW HELD AT BAY.
THE GFS MAINTAINS THE UPPER RIDGE OVER THE GREAT PLAINS WITH THE
UPPER LOW MOVING ASHORE INTO THE PACIFIC NORTHWEST. BOTH MODELS
DEPICT A SHORTWAVE MOVING NORTHEAST ACROSS WY ON SUNDAY.
DIURNAL CONVECTIVE DEVELOPMENT THROUGH LATE WEEK WILL FAVOR THE
MOUNTAINS WITH THE PLAINS REMAINING DRY UNDER THE INFLUENCE OF
THE UPPER RIDGE. A PACIFIC COLD FRONT MAKES EASTWARD PROGRESS
THROUGH MONTANA AND THE DAKOTAS LATE FRIDAY INTO SATURDAY AND
INTO THE WESTERN NEB PANHANDLE AND NORTHEAST WY BY SUNDAY.
PRECIPITABLE WATER VALUES RISE TO AROUND AN INCH THIS WEEKEND.
THE COMBINATION OF THE FRONT...SHORTWAVE AND ADDITIONAL MONSOON
MOISTURE MAY YIELD GREATER CONVECTIVE COVERAGE...INCLUDING THE
PLAINS. 700MB TEMPERATURES PEAK NEAR 17C THURSDAY AND FRIDAY WITH
HIGHS IN THE UPPER 80S TO UPPER 90S. THEY LOWER A FEW DEGREES
THIS WEEKEND WITH HIGHS IN THE LOWER 80S TO LOWER 90S SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY MORNING)
ISSUED AT 1059 AM MDT MON AUG 26 2013
DO BELIEVE THUNDERSTORM CHANCES WILL BE MAINLY CONFINED TO THE
SOUTHERN LARAMIE RANGE AS WELL AS THE KLAR AND KCYS AERODROMES
THIS AFTERNOON. LATEST HRRR COMPOSITE REFLECTIVITY FORECAST
SHOWING THIS AREA THE PRIME AREA TODAY. SO...WENT AHEAD AND ADDED
TEMPO THUNDERSTORMS IN THE KLAR AND KCYS TAFS. VFR OTHERWISE WITH
CONVECTION ENDING SHORTLY AFTER 00Z.
&&
.FIRE WEATHER...
ISSUED AT 500 AM MDT MON AUG 26 2013
A VERY BROAD AND STRONG UPPER LEVEL RIDGE WILL KEEP HOLD OF THE
CENTRAL UNITED STATES THIS WEEK. SOUTHWEST FLOW WILL BE OVER THE
DISTRICT IN THIS PATTERN...WITH HOT AND MOSTLY DRY CONDITIONS
ANTICIPATED FOR THE EASTERN PLAINS AND CHANCES FOR SHOWERS AND
THUNDERSTORMS FOR THE MOUNTAINS UNDER A MODEST MONSOONAL STREAM.
THE BEST CHANCE FOR WETTING RAINS WILL BE TODAY WITH THE BEST
AVAILABLE MOISTURE IN PLACE...AND THE DEEPEST MOISTURE WILL
STEADILY SHIFT WESTWARD THROUGH THE WEEK DIMINISHING CHANCES
OVERALL. SURFACE WINDS WILL ALSO BE ON THE GUSTY SIDE TODAY ACROSS
SOUTHEAST WYOMING...WITH WIDESPREAD GUSTS FROM THE WEST-SOUTHWEST
AT 20 TO 30 MPH. AREAS WITHIN THE WIND CORRIDOR ALONG AND WEST OF
THE LARAMIE RANGE COULD SEE GUSTS AS HIGH AS 40 MPH EARLY THIS
AFTERNOON. MINIMUM HUMIDITIES WILL STAY ABOVE CRITICAL THRESHOLDS
THOUGH...WITH VALUES ROUGHLY BETWEEN 20 AND 40 PERCENT EXPECTED
TODAY. WINDS WILL BE LESS EACH AFTERNOON FOR THE REMAINDER OF THIS
WEEK...WITH MINIMUM HUMIDITIES LOOKING TO STAY BETWEEN 20 AND 30
PERCENT EACH AFTERNOON.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...RJM
LONG TERM...JAMSKI
AVIATION...CLAYCOMB
FIRE WEATHER...RJM