Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/18/13
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1138 AM MDT THU MAY 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM MDT THU MAY 16 2013
A LINE OF RADAR ECHOES WAS MOVING THRU THE FAR ERN COUNTIES THIS
MORNING...BUT ARE EXPECTED TO BE OUT OF THE AREA BY 6 AM. A
SHORTWAVE TROF WL CONTINUE MOVING EASTWARD ACRS CO TODAY WITH THE
AXIS EXPECTED TO BE NR THE ERN BORDER BY EVENING. BEHIND THE UPR
DISTURBANCE DRIER AIR WL SPREAD FROM WEST TO EAST...BUT THERE SHOULD
STILL BE ENOUGH MSTR AROUND FOR ISOLD TO SCT SHOWERS AND TSTMS OVR
AND NR THE HYR TRRN. SOME LOW LEVEL CONVERGENCE...BETTER LOW LEVEL
MSTR AND CAPE VALUES APPROACHING 600 J/KG...ALONG WITH THE UPR SHRTWV
TROF ARE ALSO EXPECTED TO ENHANCE CHANCES FOR SHOWERS AND TSTMS OVR
THE FAR ERN COUNTIES THIS AFTERNOON. HIGH TEMPS TODAY ACRS THE AREA
WL BE ABOVE NORMAL FOR THIS TIME OF YEAR. THE UPR LEVEL DISTURBANCE
WL EXIT THE STATE THIS EVENING AND PCPN IS EXPECTED TO END BY
MIDNIGHT. THE NAM CONTINUES TO SHOW A LOT OF LOW LEVEL MSTR OVR THE
FAR EASTERN AREAS LATE TONIGHT AND WL PROBABLY RESULT IN SOME
STRATUS AND POSSIBLY FOG.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 358 AM MDT THU MAY 16 2013
FRIDAY-FRIDAY NIGHT...SOUTHWEST FLOW ALOFT PROGGED TO SLOWLY
INCREASE FROM WEST TO EAST ACROSS THE AREA AS NEXT UPPER TROUGH
DIGS ACROSS THE WEST COAST AND INTO THE GREAT BASIN FRIDAY NIGHT.
MODELS INDICATING DRY AND WARM CONDITIONS ACROSS THE AREA FRIDAY
WITH POSSIBLE CRITICAL FIRE WEATHER CONDITIONS DEVELOPING ACROSS
WESTERN PORTIONS OF THE DISTRICT FRIDAY AFTERNOON WITH INCREASING
MID LEVEL FLOW AND EXPECTED DEEP MIXING. MAY NEED SOME FIRE WEATHER
HIGHLIGHTS ESPECIALLY FOR THE SW MTS AND SAN LUIS VALLEY...THOUGH
WILL NEED TO SEE HOW FUELS ARE AT THIS TIME. WARM AIR ALOFT (10-14C
AT H7) ALONG WITH THE DOWNSLOPE FLOW WILL SUPPORT HIGH TEMPERATURES
IN THE 80S TO LOWER 90S ACROSS THE PLAINS AND MAINLY 60S AND 70S
ACROSS THE HIGHER TERRAIN AND MT VALLEYS.
SATURDAY-MONDAY...LATEST MODELS CONTINUE TO INDICATE MORE UNSETTLED
WEATHER THROUGH EARLY NEXT WEEK AS GREAT BASIN UPPER TROUGH LIFTS
OUT ACROSS THE CENTRAL ROCKIES THROUGH SATURDAY NIGHT WITH SECONDARY
ENERGY PROGGED TO DIG ACROSS THE NORTHERN GREAT BASIN AND THE
NORTHERN ROCKIES SUNDAY AND SUNDAY NIGHT. INCREASING MID AND UPPER
LEVEL MOISTURE AND UVV ACROSS THE AREA SATURDAY SUPPORTS ISOLATED TO
SCATTERED HIGH BASED CONVECTION ACROSS THE AREA SATURDAY AFTERNOON
AND EVENING...WITH BEST CHANCES OF SEEING WETTING RAINS ACROSS THE
CENTRAL AND SOUTHWEST MTS. ASSOCIATED LEE TROUGHING MOVES ACROSS THE
PLAINS THROUGH THE AFTERNOON...THOUGH LOOKS LIKE BEST LOW LEVEL
MOISTURE REMAINS WELL INTO WESTERN KANSAS. COOLING ALOFT SUPPORTS
HIGHS ON SATURDAY SOME 4-9F COOLER THAN FRIDAY...WITH POSSIBLE
CRITICAL FIRE WEATHER CONDITIONS SHIFTING OUT ACROSS THE FAR SE
PLAINS. TEMPS ALOFT COOL MORE ON SUNDAY WITH COOL AND BRISK
NORTHWEST FLOW ALOFT ACROSS THE AREA ON MONDAY AS SECONDARY ENERGY
DIGS ACROSS THE ROCKIES AND INTO THE HIGH PLAINS. ISOLATED TO
SCATTERED AFTERNOON AND EVENING POPS ACROSS THE AREA AGAIN SUNDAY
WITH PASSING SECONDARY ENERGY WITH THE GFS SUGGESTING A DRIER AND
SUBSIDENT AIRMASS ACROSS THE AREA ON MONDAY. THE LATEST
ECMWF...HOWEVER...IS A TAD SLOWER AND FURTHER SOUTH WITH THE
SECONDARY ENERGY DIGGING ACROSS THE CENTRAL ROCKIES MONDAY
AFTERNOON...WHICH WOULD KEEP THE UNSETTLED WEATHER IN PLACE ON
MONDAY. WITH THE COOLING ALOFT...SUNDAY AND MONDAY LOOK TO BE THE
COOLEST DAYS OF THE UPCOMING WEEK.
TUESDAY-THURSDAY...WARMER AND DRIER WEATHER EXPECTED AS UPPER LEVEL
RIDGING BUILDS ACROSS THE ROCKIES AHEAD OF ANOTHER TROUGH DIGGING
ACROSS THE WEST COAST WEDNESDAY. WARMING ALOFT WILL ALLOW TEMPS TO
WARM BACK TO AT AND SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH MID
WEEK. ISOLATED HIGH BASED STORMS REMAIN POSSIBLE OVER THE HIGHER
TERRAIN THROUGH MID WEEK WITH INCREASING SOUTHERLY FLOW ALOFT
THURSDAY ALLOWING FOR INCREASING LOW LEVEL MOISTURE ACROSS THE AREA
ON THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1058 AM MDT THU MAY 16 2013
VFR CONDITIONS ARE EXPECTED DURING THE NEXT 24H AT ALL 3 TAF
SITES...KPUB...KALS AND KCOS. SFC WINDS WILL BE DIURNALLY DRIVEN.
THERE IS A LOW PROBABILITY OF A PASSING SHOWER/TSRA AT KCOS LATER
THIS AFTERNOON AND EARLY EVENING...BUT PROBABILITY TOO LOW TO
MENTION EXPLICITLY IN TAF AS BOTH HRRR MODEL AND LOCAL WRF ARE
COMING IN DRY.
&&
.FIRE WEATHER...
ISSUED AT 1134 AM MDT THU MAY 16 2013
BASED ON LATEST DATA FROM FOREST SERVICE AND MODEL
GUIDANCE...WILL ISSUE A RED FLAG WARNING FOR THE SOUTHWEST
MTNS...SAN LUIS VALLEY AND THE SOUTHERN MTNS FOR TOMORROW. OTHER
AREAS WILL SEE RED FLAG CRITERIA TOMORROW...BUT THE FUELS WILL NOT
CARRY FIRE ACCORDING THE THE FOREST SERVICE FUELS PAGE.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TO 8 PM MDT FRIDAY FOR COZ222>225.
&&
$$
SHORT TERM...28
LONG TERM...MW
AVIATION...HODANISH
FIRE WEATHER...HODANISH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1128 AM MDT THU MAY 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM MDT THU MAY 16 2013
A LINE OF RADAR ECHOES WAS MOVING THRU THE FAR ERN COUNTIES THIS
MORNING...BUT ARE EXPECTED TO BE OUT OF THE AREA BY 6 AM. A
SHORTWAVE TROF WL CONTINUE MOVING EASTWARD ACRS CO TODAY WITH THE
AXIS EXPECTED TO BE NR THE ERN BORDER BY EVENING. BEHIND THE UPR
DISTURBANCE DRIER AIR WL SPREAD FROM WEST TO EAST...BUT THERE SHOULD
STILL BE ENOUGH MSTR AROUND FOR ISOLD TO SCT SHOWERS AND TSTMS OVR
AND NR THE HYR TRRN. SOME LOW LEVEL CONVERGENCE...BETTER LOW LEVEL
MSTR AND CAPE VALUES APPROACHING 600 J/KG...ALONG WITH THE UPR SHRTWV
TROF ARE ALSO EXPECTED TO ENHANCE CHANCES FOR SHOWERS AND TSTMS OVR
THE FAR ERN COUNTIES THIS AFTERNOON. HIGH TEMPS TODAY ACRS THE AREA
WL BE ABOVE NORMAL FOR THIS TIME OF YEAR. THE UPR LEVEL DISTURBANCE
WL EXIT THE STATE THIS EVENING AND PCPN IS EXPECTED TO END BY
MIDNIGHT. THE NAM CONTINUES TO SHOW A LOT OF LOW LEVEL MSTR OVR THE
FAR EASTERN AREAS LATE TONIGHT AND WL PROBABLY RESULT IN SOME
STRATUS AND POSSIBLY FOG.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 358 AM MDT THU MAY 16 2013
FRIDAY-FRIDAY NIGHT...SOUTHWEST FLOW ALOFT PROGGED TO SLOWLY
INCREASE FROM WEST TO EAST ACROSS THE AREA AS NEXT UPPER TROUGH
DIGS ACROSS THE WEST COAST AND INTO THE GREAT BASIN FRIDAY NIGHT.
MODELS INDICATING DRY AND WARM CONDITIONS ACROSS THE AREA FRIDAY
WITH POSSIBLE CRITICAL FIRE WEATHER CONDITIONS DEVELOPING ACROSS
WESTERN PORTIONS OF THE DISTRICT FRIDAY AFTERNOON WITH INCREASING
MID LEVEL FLOW AND EXPECTED DEEP MIXING. MAY NEED SOME FIRE WEATHER
HIGHLIGHTS ESPECIALLY FOR THE SW MTS AND SAN LUIS VALLEY...THOUGH
WILL NEED TO SEE HOW FUELS ARE AT THIS TIME. WARM AIR ALOFT (10-14C
AT H7) ALONG WITH THE DOWNSLOPE FLOW WILL SUPPORT HIGH TEMPERATURES
IN THE 80S TO LOWER 90S ACROSS THE PLAINS AND MAINLY 60S AND 70S
ACROSS THE HIGHER TERRAIN AND MT VALLEYS.
SATURDAY-MONDAY...LATEST MODELS CONTINUE TO INDICATE MORE UNSETTLED
WEATHER THROUGH EARLY NEXT WEEK AS GREAT BASIN UPPER TROUGH LIFTS
OUT ACROSS THE CENTRAL ROCKIES THROUGH SATURDAY NIGHT WITH SECONDARY
ENERGY PROGGED TO DIG ACROSS THE NORTHERN GREAT BASIN AND THE
NORTHERN ROCKIES SUNDAY AND SUNDAY NIGHT. INCREASING MID AND UPPER
LEVEL MOISTURE AND UVV ACROSS THE AREA SATURDAY SUPPORTS ISOLATED TO
SCATTERED HIGH BASED CONVECTION ACROSS THE AREA SATURDAY AFTERNOON
AND EVENING...WITH BEST CHANCES OF SEEING WETTING RAINS ACROSS THE
CENTRAL AND SOUTHWEST MTS. ASSOCIATED LEE TROUGHING MOVES ACROSS THE
PLAINS THROUGH THE AFTERNOON...THOUGH LOOKS LIKE BEST LOW LEVEL
MOISTURE REMAINS WELL INTO WESTERN KANSAS. COOLING ALOFT SUPPORTS
HIGHS ON SATURDAY SOME 4-9F COOLER THAN FRIDAY...WITH POSSIBLE
CRITICAL FIRE WEATHER CONDITIONS SHIFTING OUT ACROSS THE FAR SE
PLAINS. TEMPS ALOFT COOL MORE ON SUNDAY WITH COOL AND BRISK
NORTHWEST FLOW ALOFT ACROSS THE AREA ON MONDAY AS SECONDARY ENERGY
DIGS ACROSS THE ROCKIES AND INTO THE HIGH PLAINS. ISOLATED TO
SCATTERED AFTERNOON AND EVENING POPS ACROSS THE AREA AGAIN SUNDAY
WITH PASSING SECONDARY ENERGY WITH THE GFS SUGGESTING A DRIER AND
SUBSIDENT AIRMASS ACROSS THE AREA ON MONDAY. THE LATEST
ECMWF...HOWEVER...IS A TAD SLOWER AND FURTHER SOUTH WITH THE
SECONDARY ENERGY DIGGING ACROSS THE CENTRAL ROCKIES MONDAY
AFTERNOON...WHICH WOULD KEEP THE UNSETTLED WEATHER IN PLACE ON
MONDAY. WITH THE COOLING ALOFT...SUNDAY AND MONDAY LOOK TO BE THE
COOLEST DAYS OF THE UPCOMING WEEK.
TUESDAY-THURSDAY...WARMER AND DRIER WEATHER EXPECTED AS UPPER LEVEL
RIDGING BUILDS ACROSS THE ROCKIES AHEAD OF ANOTHER TROUGH DIGGING
ACROSS THE WEST COAST WEDNESDAY. WARMING ALOFT WILL ALLOW TEMPS TO
WARM BACK TO AT AND SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH MID
WEEK. ISOLATED HIGH BASED STORMS REMAIN POSSIBLE OVER THE HIGHER
TERRAIN THROUGH MID WEEK WITH INCREASING SOUTHERLY FLOW ALOFT
THURSDAY ALLOWING FOR INCREASING LOW LEVEL MOISTURE ACROSS THE AREA
ON THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1058 AM MDT THU MAY 16 2013
VFR CONDITIONS ARE EXPECTED DURING THE NEXT 24H AT ALL 3 TAF
SITES...KPUB...KALS AND KCOS. SFC WINDS WILL BE DIURNALLY DRIVEN.
THERE IS A LOW PROBABILITY OF A PASSING SHOWER/TSRA AT KCOS LATER
THIS AFTERNOON AND EARLY EVENING...BUT PROBABILITY TOO LOW TO
MENTION EXPLICITLY IN TAF AS BOTH HRRR MODEL AND LOCAL WRF ARE
COMING IN DRY.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...MW
AVIATION...HODANISH
AREA FORECAST DISCUSSION...CORRECTED
NWS DENVER/BOULDER CO
934 AM MDT THU MAY 16 2013
.CORRECTED AVIATION DISCUSSION.
.UPDATE...SHORT WAVE HAS EXITED THE AREA BUT ENOUGH MOISTURE AND
INSTABILITY BEHIND THE WAVE TO INITIATE A TSTM OVER FORT MORGAN
IN THE LAST FEW MINUTES. OVERALL FORECAST LOOKS ON TRACK. HAVE
NUDGED THE POPS UPWARD IN THE MOUNTAINS THIS AFTN. A FAIRLY
UNIFORM W-NWLY FLOW ALOFT IS PROGGED FOR THIS AFTN....SOME OF
WHICH WILL SHOULD MIX DOWN TO THE SURFACE. CAPES IN THE DENVER
AREA ARE PROGGED TO BE AROUND 400 J/KG WITH THE LOWER LEVELS
DRYING OUT. AS A RESULT...HIGH BASED ISOLATED TSTMS WITH GUSTY
OUTFLOW WINDS TO 35 KTS THE MAIN BIPRODUCT OF THE STORMS. THE PW
VALUES ARE HIGHER FURTHER EAST. EAST OF A STERLING TO AKRON
LINE...AN ISOLATED SEVERE THUNDERSTORM POSSIBLE WITH WIND GUSTS TO
60 MPH AND HAIL TO ONE INCH...ALONG WITH BRIEF HEAVY RAINFALL.
STORM MOTIONS WNWLY AT 10-15 KTS THIS AFTN.
&&
.AVIATION...WEAK BOUNDARY PUSHED THROUGH KDEN EARLIER THIS
MORNING...BUT WINDS BACK TO A S-SWLY COMPONENT. LGT WINDS AND
WEAK SFC PRESSURE GRADIENT MAKE IT HARD FOR MDLS TO KEY IN ON A
PREVAILING WIND. COULD SEE WNWLY WINDS MIX DOWN TO THE SFC WITH
THE LOWER LEVELS DRYING OUT THIS AFTN SO WL GO WITH NW WINDS THIS
AFTN IN THE TAF. SOME BOUNDARY LIKELY LINGERING NEAR OR JUST EAST OF
KDEN SO HAVE INCLUDED VCTS AS WELL WITH THE POTENTIAL FOR HIGH BASED
GUSTY OUTFLOW WINDS THIS AFTN. AS A RESULT MAY ALSO HAVE TO ADD A
TEMPO GROUP WITH GUSTS TO 35 KTS IN THE 21-01Z PERIOD IN THE 18Z
ISSUANCE.
&&
.PREV DISCUSSION... /ISSUED 407 AM MDT THU MAY 16 2013/
SHORT TERM...A WEAK UPPER LEVEL TROUGH WAS MOVING INTO NORTHEAST
COLORADO EARLY THIS MORNING WITH SCATTERED SHOWERS AND ISOLD TSTMS
OVER THE FAR NERN CORNER. THIS WK UPPER LEVEL TROUGH SHOULD EXIT
AREA BY 18Z. BY AFTN THE FLOW ALOFT WILL BE MAINLY ZONAL. LATEST
RAP IS SHOWING CAPES BLO 500 J/KG OVER THE HIGHER TERRAIN AND THE
FRONT RANGE HOWEVER OVER THE FAR NE PLAINS CAPES ARE FCST AOA 1000
J/KG. LATEST RAP SHOWS A WK BNDRY SETTING UP FM A STERLING TO
AKRON LN WHICH COULD ACT AS A FOCUS FOR STRONGER TSTM DEVELOPMENT
BY LATE AFTN INTO THE EARLY EVENING HOURS. OVERALL SHEAR WILL BE
BETTER THIS AFTN IN THIS AREA SO THERE COULD BE AN ISOLD MARGINAL
SVR STORM OR TWO. ELSEWHERE THERE WILL BE SOME WDLY SCT CONVECTION
IN THE MTNS...FOOTHILLS AND OVER THE PALMER DIVIDE. AS FOR HIGHS
850-700 MB TEMPS ARE 2-3 DEGREES WARMER THAN WED SO AFTN HIGHS
SHOULD RISE INTO THE 80S OVER NERN CO. FOR TONIGHT LOOKS LIKE
MOST CONVECTION SHOULD END BY EARLY EVENING AS SEE NOTHING TO KEEP
IT GOING AFTER SUNSET.
LONG TERM...AFTER A DRY AND WARM DAY ON FRIDAY IT LOOKS LIKE THE
REST OF THE FORECAST PERIOD WILL BE COOL AND SOMEWHAT UNSETTLED.
INITIALLY...DRY AND WARM SOUTHWESTERLY FLOW ALOFT WILL PREVAIL
FRIDAY...BRINGING ANOTHER EARLY TASTE OF SUMMER TO THE STATE.
SATURDAY WILL BE A TRANSITIONAL DAY AS AN UPPER TROUGH SETTLES
OVER THE NORTHWEST QUARTER OF THE NATION WITH COLORADO COMING
UNDER THE LEADING EDGE OF THE ADVANCING MOISTURE AND COOLER
TEMPERATURES ALOFT. TROUGHINESS WILL THEN REMAIN OVER THE FORECAST
AREA THROUGH MONDAY NIGHT AND TUESDAY. WEAK DYNAMIC LIFT
ASSOCIATED WITH THE UPPER TROUGH WILL BE OVER THE STATE FOR
SEVERAL DAYS WITH INEVITABLE SHORT WAVE DISTURBANCES MOVING
THROUGH THE TROUGH AT TIMES. ALL THIS SHOULD COMBINE WITH DAILY
HEATING TO PRODUCE ROUNDS OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS. AT LOWER LEVELS...IT APPEARS THAT THE SURFACE LOW
WILL REMAIN FAR ENOUGH EAST TO KEEP GULF MOISTURE MORE IN KANSAS
THAN IN EASTERN COLORADO. STILL ENOUGH MOISTURE SHOULD BE AROUND
FOR LIGHT TO MODERATE PRECIPITATION AT TIMES EACH DAY.
TEMPERATURES WILL GET PROGRESSIVELY COOLER THROUGH MONDAY AND THEN
BEGIN WARMING TUESDAY AND WEDNESDAY AS THE UPPER TROUGH FINALLY
MOVES OUT OF STATE AND AN UPPER RIDGE MOVES IN FROM THE WEST.
WITHOUT STRONG DYNAMICS OR ANY APPRECIABLE JET STREAM WINDS...IT
DOES APPEAR THAT THUNDERSTORMS THROUGH THE WEEKEND WILL LACK
ORGANIZATION WHICH WILL LIMIT THE POTENTIAL FOR SEVERE WEATHER. ON
THE OTHER HAND...STORM MOTIONS COULD BE SLOW AT TIMES MAKING
LOCALIZED HEAVY RAIN POSSIBLE...ESPECIALLY IF ANY GULF MOISTURE
SNEAKS IN FROM THE EAST.
AVIATION...COULD SEE AN ISOLD TSTM OR TWO THIS AFTN IN THE
22Z-01Z PERIOD ESPECIALLY SOUTH OF DIA SO FOR NOW WILL KEEP NEXT
TAF VOID OF TSTMS. WINDS EARLY THIS MORNING WERE DRAINAGE. BY MID
TO LATE MORNING THE NAM AND RAP SHOW WINDS RATHER LIGHT AND
VARIABLE AROUND 5 KTS. BY EARLY AFTN THE RAP HAS THE WINDS ESE AND
THEN MORE SSW BY 21Z. MEANWHILE THE NAM HAS THE WINDS BECOMING WNW
BY 18Z AND KEEPS THEM THAT WAY THRU 00Z. AT THIS POINT NOT SURE
WHICH WAY TO TREND THEM. WITH WLY MID LVL FLOW OUTFLOW BOUNDARIES
FM CONVECTION IN THE FOOTHILLS COULD TURN THE WINDS MORE WNW BY
21Z SO WILL FOLLOW NAM FOR NOW. BY EARLY THIS EVENING WINDS SHOULD
GRADUALLY BECOME DRAINAGE AFTER SUNSET.
HYDROLOGY...THERE WILL BE SOME WIDELY SCATTERED HIGHER BASED
THUNDERSTORMS THIS AFTERNOON NR THE BURN AREAS HOWEVER RAINFALL
AMOUNTS SHOULD BE UNDER A QUARTER INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....DANKERS
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
929 AM MDT THU MAY 16 2013
.UPDATE...SHORT WAVE HAS EXITED THE AREA BUT ENOUGH MOISTURE AND
INSTABILITY BEHIND THE WAVE TO INITIATE A TSTM OVER FORT MORGAN
IN THE LAST FEW MINUTES. OVERALL FORECAST LOOKS ON TRACK. HAVE
NUDGED THE POPS UPWARD IN THE MOUNTAINS THIS AFTN. A FAIRLY
UNIFORM W-NWLY FLOW ALOFT IS PROGGED FOR THIS AFTN....SOME OF
WHICH WILL SHOULD MIX DOWN TO THE SURFACE. CAPES IN THE DENVER
AREA ARE PROGGED TO BE AROUND 400 J/KG WITH THE LOWER LEVELS
DRYING OUT. AS A RESULT...HIGH BASED ISOLATED TSTMS WITH GUSTY
OUTFLOW WINDS TO 35 KTS THE MAIN BIPRODUCT OF THE STORMS. THE PW
VALUES ARE HIGHER FURTHER EAST. EAST OF A STERLING TO AKRON
LINE...AN ISOLATED SEVERE THUNDERSTORM POSSIBLE WITH WIND GUSTS TO
60 MPH AND HAIL TO ONE INCH...ALONG WITH BRIEF HEAVY RAINFALL.
STORM MOTIONS WNWLY AT 10-15 KTS THIS AFTN.
&&
.AVIATION...WEAK BOUNDARY PUSHED THROUGH KDEN EARLIER THIS
MORNING...BUT WINDS BACK TO A S-SWLY COMPONENT. LGT WINDS AND
WEAK SFC PRESSURE GRADIENT MAKE IT HARD FOR MDLS TO KEY IN ON A
PREVAILING WIND. COULD SEE WNWLY WINDS MIX DOWN TO THE SFC WITH
THE LOWER LEVELS DRYING OUT THIS AFTN SO WL GO WITH NW WINDS THIS
AFTN IN THE TAF. SOME BOUNDARY LIKELY LINGERING NEAR OR JUST EAST
OF KDEN SO HAVE INCLUDED VCTS AS WELL WITH THE POTENTIAL FOR HIGH
BASED GUSTY OUTFLOW WINDS THIS AFTN. AS A RESULT HAVE ADD A TEMPO
GROUP WITH GUSTS TO 35 KTS IN THE 21-01Z PERIOD.
&&
.PREV DISCUSSION... /ISSUED 407 AM MDT THU MAY 16 2013/
SHORT TERM...A WEAK UPPER LEVEL TROUGH WAS MOVING INTO NORTHEAST
COLORADO EARLY THIS MORNING WITH SCATTERED SHOWERS AND ISOLD TSTMS
OVER THE FAR NERN CORNER. THIS WK UPPER LEVEL TROUGH SHOULD EXIT
AREA BY 18Z. BY AFTN THE FLOW ALOFT WILL BE MAINLY ZONAL. LATEST
RAP IS SHOWING CAPES BLO 500 J/KG OVER THE HIGHER TERRAIN AND THE
FRONT RANGE HOWEVER OVER THE FAR NE PLAINS CAPES ARE FCST AOA 1000
J/KG. LATEST RAP SHOWS A WK BNDRY SETTING UP FM A STERLING TO
AKRON LN WHICH COULD ACT AS A FOCUS FOR STRONGER TSTM DEVELOPMENT
BY LATE AFTN INTO THE EARLY EVENING HOURS. OVERALL SHEAR WILL BE
BETTER THIS AFTN IN THIS AREA SO THERE COULD BE AN ISOLD MARGINAL
SVR STORM OR TWO. ELSEWHERE THERE WILL BE SOME WDLY SCT CONVECTION
IN THE MTNS...FOOTHILLS AND OVER THE PALMER DIVIDE. AS FOR HIGHS
850-700 MB TEMPS ARE 2-3 DEGREES WARMER THAN WED SO AFTN HIGHS
SHOULD RISE INTO THE 80S OVER NERN CO. FOR TONIGHT LOOKS LIKE
MOST CONVECTION SHOULD END BY EARLY EVENING AS SEE NOTHING TO KEEP
IT GOING AFTER SUNSET.
LONG TERM...AFTER A DRY AND WARM DAY ON FRIDAY IT LOOKS LIKE THE
REST OF THE FORECAST PERIOD WILL BE COOL AND SOMEWHAT UNSETTLED.
INITIALLY...DRY AND WARM SOUTHWESTERLY FLOW ALOFT WILL PREVAIL
FRIDAY...BRINGING ANOTHER EARLY TASTE OF SUMMER TO THE STATE.
SATURDAY WILL BE A TRANSITIONAL DAY AS AN UPPER TROUGH SETTLES
OVER THE NORTHWEST QUARTER OF THE NATION WITH COLORADO COMING
UNDER THE LEADING EDGE OF THE ADVANCING MOISTURE AND COOLER
TEMPERATURES ALOFT. TROUGHINESS WILL THEN REMAIN OVER THE FORECAST
AREA THROUGH MONDAY NIGHT AND TUESDAY. WEAK DYNAMIC LIFT
ASSOCIATED WITH THE UPPER TROUGH WILL BE OVER THE STATE FOR
SEVERAL DAYS WITH INEVITABLE SHORT WAVE DISTURBANCES MOVING
THROUGH THE TROUGH AT TIMES. ALL THIS SHOULD COMBINE WITH DAILY
HEATING TO PRODUCE ROUNDS OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS. AT LOWER LEVELS...IT APPEARS THAT THE SURFACE LOW
WILL REMAIN FAR ENOUGH EAST TO KEEP GULF MOISTURE MORE IN KANSAS
THAN IN EASTERN COLORADO. STILL ENOUGH MOISTURE SHOULD BE AROUND
FOR LIGHT TO MODERATE PRECIPITATION AT TIMES EACH DAY.
TEMPERATURES WILL GET PROGRESSIVELY COOLER THROUGH MONDAY AND THEN
BEGIN WARMING TUESDAY AND WEDNESDAY AS THE UPPER TROUGH FINALLY
MOVES OUT OF STATE AND AN UPPER RIDGE MOVES IN FROM THE WEST.
WITHOUT STRONG DYNAMICS OR ANY APPRECIABLE JET STREAM WINDS...IT
DOES APPEAR THAT THUNDERSTORMS THROUGH THE WEEKEND WILL LACK
ORGANIZATION WHICH WILL LIMIT THE POTENTIAL FOR SEVERE WEATHER. ON
THE OTHER HAND...STORM MOTIONS COULD BE SLOW AT TIMES MAKING
LOCALIZED HEAVY RAIN POSSIBLE...ESPECIALLY IF ANY GULF MOISTURE
SNEAKS IN FROM THE EAST.
AVIATION...COULD SEE AN ISOLD TSTM OR TWO THIS AFTN IN THE
22Z-01Z PERIOD ESPECIALLY SOUTH OF DIA SO FOR NOW WILL KEEP NEXT
TAF VOID OF TSTMS. WINDS EARLY THIS MORNING WERE DRAINAGE. BY MID
TO LATE MORNING THE NAM AND RAP SHOW WINDS RATHER LIGHT AND
VARIABLE AROUND 5 KTS. BY EARLY AFTN THE RAP HAS THE WINDS ESE AND
THEN MORE SSW BY 21Z. MEANWHILE THE NAM HAS THE WINDS BECOMING WNW
BY 18Z AND KEEPS THEM THAT WAY THRU 00Z. AT THIS POINT NOT SURE
WHICH WAY TO TREND THEM. WITH WLY MID LVL FLOW OUTFLOW BOUNDARIES
FM CONVECTION IN THE FOOTHILLS COULD TURN THE WINDS MORE WNW BY
21Z SO WILL FOLLOW NAM FOR NOW. BY EARLY THIS EVENING WINDS SHOULD
GRADUALLY BECOME DRAINAGE AFTER SUNSET.
HYDROLOGY...THERE WILL BE SOME WIDELY SCATTERED HIGHER BASED
THUNDERSTORMS THIS AFTERNOON NR THE BURN AREAS HOWEVER RAINFALL
AMOUNTS SHOULD BE UNDER A QUARTER INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....DANKERS
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
407 AM MDT THU MAY 16 2013
.SHORT TERM...A WEAK UPPER LEVEL TROUGH WAS MOVING INTO NORTHEAST
COLORADO EARLY THIS MORNING WITH SCATTERED SHOWERS AND ISOLD TSTMS
OVER THE FAR NERN CORNER. THIS WK UPPER LEVEL TROUGH SHOULD EXIT
AREA BY 18Z. BY AFTN THE FLOW ALOFT WILL BE MAINLY ZONAL. LATEST
RAP IS SHOWING CAPES BLO 500 J/KG OVER THE HIGHER TERRAIN AND THE
FRONT RANGE HOWEVER OVER THE FAR NE PLAINS CAPES ARE FCST AOA 1000
J/KG. LATEST RAP SHOWS A WK BNDRY SETTING UP FM A STERLING TO
AKRON LN WHICH COULD ACT AS A FOCUS FOR STRONGER TSTM DEVELOPMENT
BY LATE AFTN INTO THE EARLY EVENING HOURS. OVERALL SHEAR WILL BE
BETTER THIS AFTN IN THIS AREA SO THERE COULD BE AN ISOLD MARGINAL
SVR STORM OR TWO. ELSEWHERE THERE WILL BE SOME WDLY SCT CONVECTION
IN THE MTNS...FOOTHILLS AND OVER THE PALMER DIVIDE. AS FOR HIGHS
850-700 MB TEMPS ARE 2-3 DEGREES WARMER THAN WED SO AFTN HIGHS
SHOULD RISE INTO THE 80S OVER NERN CO. FOR TONIGHT LOOKS LIKE
MOST CONVECTION SHOULD END BY EARLY EVENING AS SEE NOTHING TO KEEP
IT GOING AFTER SUNSET.
.LONG TERM...AFTER A DRY AND WARM DAY ON FRIDAY IT LOOKS LIKE THE
REST OF THE FORECAST PERIOD WILL BE COOL AND SOMEWHAT UNSETTLED.
INITIALLY...DRY AND WARM SOUTHWESTERLY FLOW ALOFT WILL PREVAIL
FRIDAY...BRINGING ANOTHER EARLY TASTE OF SUMMER TO THE STATE.
SATURDAY WILL BE A TRANSITIONAL DAY AS AN UPPER TROUGH SETTLES
OVER THE NORTHWEST QUARTER OF THE NATION WITH COLORADO COMING
UNDER THE LEADING EDGE OF THE ADVANCING MOISTURE AND COOLER
TEMPERATURES ALOFT. TROUGHINESS WILL THEN REMAIN OVER THE FORECAST
AREA THROUGH MONDAY NIGHT AND TUESDAY. WEAK DYNAMIC LIFT
ASSOCIATED WITH THE UPPER TROUGH WILL BE OVER THE STATE FOR
SEVERAL DAYS WITH INEVITABLE SHORT WAVE DISTURBANCES MOVING
THROUGH THE TROUGH AT TIMES. ALL THIS SHOULD COMBINE WITH DAILY
HEATING TO PRODUCE ROUNDS OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS. AT LOWER LEVELS...IT APPEARS THAT THE SURFACE LOW
WILL REMAIN FAR ENOUGH EAST TO KEEP GULF MOISTURE MORE IN KANSAS
THAN IN EASTERN COLORADO. STILL ENOUGH MOISTURE SHOULD BE AROUND
FOR LIGHT TO MODERATE PRECIPITATION AT TIMES EACH DAY.
TEMPERATURES WILL GET PROGRESSIVELY COOLER THROUGH MONDAY AND THEN
BEGIN WARMING TUESDAY AND WEDNESDAY AS THE UPPER TROUGH FINALLY
MOVES OUT OF STATE AND AN UPPER RIDGE MOVES IN FROM THE WEST.
WITHOUT STRONG DYNAMICS OR ANY APPRECIABLE JET STREAM WINDS...IT
DOES APPEAR THAT THUNDERSTORMS THROUGH THE WEEKEND WILL LACK
ORGANIZATION WHICH WILL LIMIT THE POTENTIAL FOR SEVERE WEATHER. ON
THE OTHER HAND...STORM MOTIONS COULD BE SLOW AT TIMES MAKING
LOCALIZED HEAVY RAIN POSSIBLE...ESPECIALLY IF ANY GULF MOISTURE
SNEAKS IN FROM THE EAST.
&&
.AVIATION...COULD SEE AN ISOLD TSTM OR TWO THIS AFTN IN THE
22Z-01Z PERIOD ESPECIALLY SOUTH OF DIA SO FOR NOW WILL KEEP NEXT
TAF VOID OF TSTMS. WINDS EARLY THIS MORNING WERE DRAINAGE. BY MID
TO LATE MORNING THE NAM AND RAP SHOW WINDS RATHER LIGHT AND
VARIABLE AROUND 5 KTS. BY EARLY AFTN THE RAP HAS THE WINDS ESE AND
THEN MORE SSW BY 21Z. MEANWHILE THE NAM HAS THE WINDS BECOMING WNW
BY 18Z AND KEEPS THEM THAT WAY THRU 00Z. AT THIS POINT NOT SURE
WHICH WAY TO TREND THEM. WITH WLY MID LVL FLOW OUTFLOW BOUNDARIES
FM CONVECTION IN THE FOOTHILLS COULD TURN THE WINDS MORE WNW BY
21Z SO WILL FOLLOW NAM FOR NOW. BY EARLY THIS EVENING WINDS SHOULD
GRADUALLY BECOME DRAINAGE AFTER SUNSET.
&&
.HYDROLOGY...THERE WILL BE SOME WIDELY SCATTERED HIGHER BASED
THUNDERSTORMS THIS AFTERNOON NR THE BURN AREAS HOWEVER RAINFALL
AMOUNTS SHOULD BE UNDER A QUARTER INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
506 PM EDT THU MAY 16 2013
.SYNOPSIS...
A COLD FRONT WILL PUSH TO OUR SOUTH TONIGHT AND STALL TO OUR SOUTH
THROUGH THE UPCOMING WEEKEND. THE FRONTAL BOUNDARY IS EXPECTED TO
RETURN NORTHWARD AS A WARM FRONT LATE MONDAY INTO TUESDAY. ANOTHER
FRONTAL SYSTEM IS EXPECTED TO APPROACH THE AREA FROM THE WEST AND
MOVE THROUGH THE AREA DURING THE MIDDLE TO LATE PART OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
WE LOWERED AREAL COVERAGE TO ISOLATED AS LATEST LAPS SOUNDINGS ALL
HAVE CAPES LESS THAN 1K JOULES. IF THERE IS A WINDOW FOR A TSRA TO
POP, IT IS FAIRLY SMALL AND ITS CLOSING FAST.
DURING THE AFTERNOON, INSTABILITY AND MOISTURE WERE TRYING TO MOVE
IN FROM THE SOUTHWEST ACROSS THE AREA NEAR AND SOUTH OF THE I-78
CORRIDOR TO TAP SOME LINGERING MID LEVEL FORCING. AS ONE MOVED
FURTHER EAST ACROSS THAT AREA, THERE STILL WAS A CONSIDERABLE AMOUNT
OF CIN TO OVERCOME AS OF 18Z. OUR TAKE ON THIS IS THAT THE BEST
CHANCES FOR ACTIVITY EARLY IN THE NEAR TERM ARE OVER THE
SOUTHWESTERN PART OF THE FORECAST AREA, ALTHOUGH THE LATEST HRRR RUN
BROUGHT SOME SCATTERED ACTIVITY FURTHER NORTH. SINCE IT WAS FAIRLY
ACCURATE WITH THE MORNING ACTIVITY, WE KEPT A SLIGHT CHANCE WHERE
THE RAPID REFRESH INDICATED, BUT WE HAVE THE BEST CHANCE SOUTH OF
THE MASON-DIXON LINE. WE EXPECT TO LOSE ANY CONVECTION BY MIDNIGHT
AS A SECONDARY COLD FRONT WILL DROP ACROSS THE AREA AND PUSH DRIER
AIR SOUTH.
TEMPERATURES ARE A GUIDANCE/CONTINUITY BLEND. UP NORTH, THERE MAY BE
SOME RADIATING WITH LOWER DEW POINTS ALREADY IN PLACE AND WINDS
EXPECTED TO GO LIGHT AT LEAST INTO THE EVENING HOURS. THE SECONDARY
FRONT MAY MIX THINGS A BIT AND TURN THE REST OF THE NIGHT INTO A
MILDLY ADVECTIVE ONE.
&&
.SHORT TERM /6 AM FRIDAY THROUGH 6 AM FRIDAY/...
OUR FORECAST IS THAT THE SURFACE HIGH RIDGING DOWN FROM CENTRAL
CANADA AND SOME LOCAL MID LEVEL RIDGING TO OUR WEST (AHEAD OF A SLOW
MOVING SYSTEM THAT WAS THE CLOSED LOW RESPONSIBLE FOR THE SPLIT FLOW
EARLIER IN THE WEEK) WILL CARVE OUT A DRY DAY FOR THE ENTIRE
FORECAST AREA. THERE SHOULD BE A DECENT AMOUNT OF SUNSHINE, ALTHOUGH
SOME HIGH CLOUDINESS MAY BEGIN TO INVADE FROM THE SOUTH AND WEST
DURING THE COURSE OF THE DAY. WINDS SHOULD BE RATHER LIGHT AS HIGH
PRESSURE MOVES OVER US. TEMPERATURES ARE A GUIDANCE/CONTINUITY BLEND
IN LINE WITH H925 TEMPERATURES, AND ARE FORECAST TO BE A BIT ABOVE
NORMAL. THE CAVEAT IS THAT WE EXPECT A SEA BREEZE TO DEVELOP DURING
THE COURSE OF THE DAY.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
THE COLD FRONT WILL REMAIN STALLED TO OUR SOUTH FOR THE UPCOMING
WEEKEND. FRIDAY NIGHT INTO SATURDAY, HIGH PRESSURE WILL NOSE DOWN
ACROSS OUR AREA FROM THE NORTH, KEEPING THE FRONT TO OUR SOUTH AND
KEEPING OUR AREA IN MORE OF AN EASTERLY/SOUTHEASTERLY FLOW. SOME
GUIDANCE IS TRYING TO BRING SOME LIGHT QPF ACROSS THE AREA AS EARLY
AS FRIDAY NIGHT, BUT WE WILL KEEP FRIDAY NIGHT DRY. AS WE MOVE INTO
THE WEEKEND, A SLOW MOVING SHORT WAVE WILL BE SLIDING ACROSS THE
OHIO RIVER VALLEY AND TOWARD THE EAST COAST. THIS WILL PUSH SEVERAL
WEAK DISTURBANCES ACROSS THE AREA THROUGH THE WEEKEND, WHICH MAY
HELP CREATE SOME SHOWER ACTIVITY. THE AIRMASS SHOULD BE FAIRLY
STABLE, SO WE ARE NOT EXPECTING THUNDERSTORMS AT THIS TIME. WITH THE
EASTERLY/SOUTHEASTERLY FLOW, TEMPERATURES ARE NOT EXPECTED TO WARM
SIGNIFICANTLY EITHER.
AS THE HIGH PRESSURE REMAINS TO OUR NORTHEAST AND SLOWLY BUILDS OUT
TO SEA MONDAY INTO TUESDAY, MOISTURE WILL CONTINUE TO PUSH ACROSS
THE AREA THROUGH EARLY NEXT WEEK. THE FRONTAL BOUNDARY TO OUR SOUTH
IS EXPECTED TO BEGIN PUSHING BACK NORTHWARD AS A WARM FRONT AS WELL,
AND MAY MOVE THROUGH THE AREA BY MONDAY NIGHT INTO TUESDAY. WE COULD
CONTINUE TO SEE SOME PRECIPITATION ACROSS THE AREA AHEAD OF THE WARM
FRONTAL BOUNDARY AS SEVERAL WEAK DISTURBANCES MOVE ACROSS THE AREA
IN THE WESTERLY FLOW ALOFT.
AFTER THE WARM FRONT MOVES THROUGH, TUESDAY AND WEDNESDAY OF NEXT
WEEK LOOK TO BE THE WARMEST DAYS. WE DID NOT GO AS HIGH AS WHAT THE
850 MB ECMWF/GFS TEMPS WOULD FORECAST FOR SURFACE MAXES, BUT WE
SHOULD BE ABLE TO REACH AT LEAST THE LOW 80S FOR MUCH OF THE AREA.
WE WILL KEEP A CHANCE OF SHOWERS/THUNDERSTORMS IN THE FORECAST
TUESDAY/WEDNESDAY AS WE SHOULD BE IN THE WARM SECTOR AHEAD OF THE
NEXT APPROACHING FRONTAL SYSTEM. ANY SHORT WAVES/VORT MAXES COULD
HELP CREATE SHOWERS/THUNDERSTORMS WITH THE AVAILABLE INSTABILITY.
THE LATEST GFS/ECMWF VARY ON THEIR TIMING OF THE NEXT FRONTAL
SYSTEM. THE GFS BRINGS THE FRONT THROUGH WEDNESDAY NIGHT INTO
THURSDAY, WHILE THE ECMWF BRINGS IT THROUGH THURSDAY NIGHT INTO
FRIDAY. BEING SO FAR OUT, WE WILL KEEP A CHANCE OF SHOWERS IN THE
FORECAST THROUGH THURSDAY NIGHT FOR NOW.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
SHOWER ACTIVITY HAD SLIPPED INTO THE MARYLAND EASTERN SHORE,
CENTRAL AND SOUTHERN DELAWARE AND FAR SOUTHERN NJ EARLY THIS
AFTERNOON. RADAR TRENDS SUGGESTED THAT ONLY SOME LIGHT SHOWERS
THREATENED THE SOUTHEASTERN TAF SITES EARLY. FURTHER NORTH, THERE IS
ONLY A SLIGHT CHANCE OF ANY ACTIVITY. ALL THE TAFS ARE VFR WITH SOME
CUMULUS EARLY AND THEN MID AND HIGH CLOUDS RECEDING SOUTHWARD TONIGHT.
MAINLY HIGH CLOUDS WITH PERHAPS A FEW CUMULUS ARE EXPECTED ON
FRIDAY. DRIER AIR IS EXPECTED TO MOVE DOWN FROM THE NORTH TONIGHT,
SO WE DON`T FORECAST ANY OVERNIGHT VISIBILITY RESTRICTIONS.
REGARDING WINDS, THE LATEST MODELS SHOW THEM PICKING UP FROM OUT OF
THE WEST EARLY IN THE TAF PERIOD WITH SOME GUSTS ABOVE 20 KT
POSSIBLE, THEN THEY SHOULD RELAX THIS EVENING BEFORE SHIFTING TO THE
NORTH OVERNIGHT THANKS TO A SECONDARY COLD FRONT. GENERALLY, WINDS
SHOULD BE RATHER GENTLE ON FRIDAY.
A SEA BREEZE HAD DEVELOPED AT ACY EARLIER TODAY, BUT WE THINK THE
STRENGTHENING WEST WIND WILL OVERWHELM IT EARLY IN THE TAF PERIOD. A
SEA BREEZE LIKELY WILL AFFECT ACY ON FRIDAY.
OUTLOOK...
FRIDAY NIGHT...MOSTLY VFR.
SATURDAY-SATURDAY NIGHT...MAINLY VFR WITH LOWERING CLOUDS. A
SLIGHT CHANCE OF SHOWERS AND SOUTH TO SOUTHEAST WINDS AROUND 5
KNOTS.
SUNDAY-SUNDAY NIGHT...GENERALLY VFR EXPECTED, POSSIBLE MVFR CIGS,
ESPECIALLY WITH ANY SHOWERS.
MONDAY-TUESDAY...GENERALLY VFR, POSSIBLE MVFR CIGS/VSBYS,
ESPECIALLY WITH ANY SHOWERS/THUNDERSTORMS.
&&
.MARINE...
WE WILL LET THE SCA FOR HAZARDOUS SEAS EXPIRE AS SEAS ARE TRENDING
DOWNWARD AT BUOY 65. WINDS AND SEAS OVER ALL WATERS ARE NOW BELOW
ADVISORY CRITERIA THROUGH FRIDAY.
LIGHT WINDS THROUGH THIS EVENING ARE EXPECTED TO BECOME NORTHERLY
AND PICK UP SOME AS A SECONDARY COLD FRONT DROPS ACROSS THE COASTAL
WATERS OF NEW JERSEY AND DELAWARE. FORECAST PRESSURE RISES SUPPORT A
MODERATE BUT NOT ADVISORY LEVEL WIND. WINDS SHOULD DIMINISH AGAIN ON
FRIDAY. THE WINDS MAY BECOME ONSHORE NEAR LAND.
OUTLOOK...
CONDITIONS SHOULD REMAIN BELOW ADVISORY LEVELS THROUGH SATURDAY.
HOWEVER, WINDS MAY RETURN CLOSE TO ADVISORY LEVELS STARTING
SATURDAY NIGHT INTO SUNDAY AS THE PRESSURE GRADIENT TIGHTENS
ACROSS THE WATERS AS HIGH PRESSURE PUSHES OFF THE NORTHEAST COAST.
WITH THE EASTERLY/SOUTHEASTERLY FLOW, SEAS MAY RETURN TO SMALL
CRAFT ADVISORY LEVELS DUE TO THE LONG FETCH STARTING SUNDAY AND
CONTINUING INTO TUESDAY.
&&
.FIRE WEATHER...
WE WILL MENTION IN THE FIRE WEATHER FORECAST THAN MINIMUM RELATIVE
HUMIDITY LEVELS WILL DROP TO OR BELOW 30 PERCENT ON FRIDAY AFTERNOON
FOR MUCH OF THE FORECAST AREA. WINDS AND FINE FUELS ARE NOT A
CONCERN.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ROBERTSON
NEAR TERM...DELISI
SHORT TERM...DELISI
LONG TERM...ROBERTSON
AVIATION...DELISI/ROBERTSON
MARINE...DELISI/GIGI/ROBERTSON
FIRE WEATHER...DELISI
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
356 PM EDT THU MAY 16 2013
.SYNOPSIS...
A COLD FRONT WILL PUSH TO OUR SOUTH TONIGHT AND STALL TO OUR SOUTH
THROUGH THE UPCOMING WEEKEND. THE FRONTAL BOUNDARY IS EXPECTED TO
RETURN NORTHWARD AS A WARM FRONT LATE MONDAY INTO TUESDAY. ANOTHER
FRONTAL SYSTEM IS EXPECTED TO APPROACH THE AREA FROM THE WEST AND
MOVE THROUGH THE AREA DURING THE MIDDLE TO LATE PART OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
DURING THE AFTERNOON, INSTABILITY AND MOISTURE WERE TRYING TO MOVE
IN FROM THE SOUTHWEST ACROSS THE AREA NEAR AND SOUTH OF THE I-78
CORRIDOR TO TAP SOME LINGERING MID LEVEL FORCING. AS ONE MOVED
FURTHER EAST ACROSS THAT AREA, THERE STILL WAS A CONSIDERABLE AMOUNT
OF CIN TO OVERCOME AS OF 18Z. OUR TAKE ON THIS IS THAT THE BEST
CHANCES FOR ACTIVITY EARLY IN THE NEAR TERM ARE OVER THE
SOUTHWESTERN PART OF THE FORECAST AREA, ALTHOUGH THE LATEST HRRR RUN
BROUGHT SOME SCATTERED ACTIVITY FURTHER NORTH. SINCE IT WAS FAIRLY
ACCURATE WITH THE MORNING ACTIVITY, WE KEPT A SLIGHT CHANCE WHERE
THE RAPID REFRESH INDICATED, BUT WE HAVE THE BEST CHANCE SOUTH OF
THE MASON-DIXON LINE. WE EXPECT TO LOSE ANY CONVECTION BY MIDNIGHT
AS A SECONDARY COLD FRONT WILL DROP ACROSS THE AREA AND PUSH DRIER
AIR SOUTH.
TEMPERATURES ARE A GUIDANCE/CONTINUITY BLEND. UP NORTH, THERE MAY BE
SOME RADIATING WITH LOWER DEW POINTS ALREADY IN PLACE AND WINDS
EXPECTED TO GO LIGHT AT LEAST INTO THE EVENING HOURS. THE SECONDARY
FRONT MAY MIX THINGS A BIT AND TURN THE REST OF THE NIGHT INTO A
MILDLY ADVECTIVE ONE.
&&
.SHORT TERM /6 AM FRIDAY THROUGH 6 AM FRIDAY/...
OUR FORECAST IS THAT THE SURFACE HIGH RIDGING DOWN FROM CENTRAL
CANADA AND SOME LOCAL MID LEVEL RIDGING TO OUR WEST (AHEAD OF A SLOW
MOVING SYSTEM THAT WAS THE CLOSED LOW RESPONSIBLE FOR THE SPLIT FLOW
EARLIER IN THE WEEK) WILL CARVE OUT A DRY DAY FOR THE ENTIRE
FORECAST AREA. THERE SHOULD BE A DECENT AMOUNT OF SUNSHINE, ALTHOUGH
SOME HIGH CLOUDINESS MAY BEGIN TO INVADE FROM THE SOUTH AND WEST
DURING THE COURSE OF THE DAY. WINDS SHOULD BE RATHER LIGHT AS HIGH
PRESSURE MOVES OVER US. TEMPERATURES ARE A GUIDANCE/CONTINUITY BLEND
IN LINE WITH H925 TEMPERATURES, AND ARE FORECAST TO BE A BIT ABOVE
NORMAL. THE CAVEAT IS THAT WE EXPECT A SEA BREEZE TO DEVELOP DURING
THE COURSE OF THE DAY.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
THE COLD FRONT WILL REMAIN STALLED TO OUR SOUTH FOR THE UPCOMING
WEEKEND. FRIDAY NIGHT INTO SATURDAY, HIGH PRESSURE WILL NOSE DOWN
ACROSS OUR AREA FROM THE NORTH, KEEPING THE FRONT TO OUR SOUTH AND
KEEPING OUR AREA IN MORE OF AN EASTERLY/SOUTHEASTERLY FLOW. SOME
GUIDANCE IS TRYING TO BRING SOME LIGHT QPF ACROSS THE AREA AS EARLY
AS FRIDAY NIGHT, BUT WE WILL KEEP FRIDAY NIGHT DRY. AS WE MOVE INTO
THE WEEKEND, A SLOW MOVING SHORT WAVE WILL BE SLIDING ACROSS THE
OHIO RIVER VALLEY AND TOWARD THE EAST COAST. THIS WILL PUSH SEVERAL
WEAK DISTURBANCES ACROSS THE AREA THROUGH THE WEEKEND, WHICH MAY
HELP CREATE SOME SHOWER ACTIVITY. THE AIRMASS SHOULD BE FAIRLY
STABLE, SO WE ARE NOT EXPECTING THUNDERSTORMS AT THIS TIME. WITH THE
EASTERLY/SOUTHEASTERLY FLOW, TEMPERATURES ARE NOT EXPECTED TO WARM
SIGNIFICANTLY EITHER.
AS THE HIGH PRESSURE REMAINS TO OUR NORTHEAST AND SLOWLY BUILDS OUT
TO SEA MONDAY INTO TUESDAY, MOISTURE WILL CONTINUE TO PUSH ACROSS
THE AREA THROUGH EARLY NEXT WEEK. THE FRONTAL BOUNDARY TO OUR SOUTH
IS EXPECTED TO BEGIN PUSHING BACK NORTHWARD AS A WARM FRONT AS WELL,
AND MAY MOVE THROUGH THE AREA BY MONDAY NIGHT INTO TUESDAY. WE COULD
CONTINUE TO SEE SOME PRECIPITATION ACROSS THE AREA AHEAD OF THE WARM
FRONTAL BOUNDARY AS SEVERAL WEAK DISTURBANCES MOVE ACROSS THE AREA
IN THE WESTERLY FLOW ALOFT.
AFTER THE WARM FRONT MOVES THROUGH, TUESDAY AND WEDNESDAY OF NEXT
WEEK LOOK TO BE THE WARMEST DAYS. WE DID NOT GO AS HIGH AS WHAT THE
850 MB ECMWF/GFS TEMPS WOULD FORECAST FOR SURFACE MAXES, BUT WE
SHOULD BE ABLE TO REACH AT LEAST THE LOW 80S FOR MUCH OF THE AREA.
WE WILL KEEP A CHANCE OF SHOWERS/THUNDERSTORMS IN THE FORECAST
TUESDAY/WEDNESDAY AS WE SHOULD BE IN THE WARM SECTOR AHEAD OF THE
NEXT APPROACHING FRONTAL SYSTEM. ANY SHORT WAVES/VORT MAXES COULD
HELP CREATE SHOWERS/THUNDERSTORMS WITH THE AVAILABLE INSTABILITY.
THE LATEST GFS/ECMWF VARY ON THEIR TIMING OF THE NEXT FRONTAL
SYSTEM. THE GFS BRINGS THE FRONT THROUGH WEDNESDAY NIGHT INTO
THURSDAY, WHILE THE ECMWF BRINGS IT THROUGH THURSDAY NIGHT INTO
FRIDAY. BEING SO FAR OUT, WE WILL KEEP A CHANCE OF SHOWERS IN THE
FORECAST THROUGH THURSDAY NIGHT FOR NOW.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
SHOWER ACTIVITY HAD SLIPPED INTO THE MARYLAND EASTERN SHORE,
CENTRAL AND SOUTHERN DELAWARE AND FAR SOUTHERN NJ EARLY THIS
AFTERNOON. RADAR TRENDS SUGGESTED THAT ONLY SOME LIGHT SHOWERS
THREATENED THE SOUTHEASTERN TAF SITES EARLY. FURTHER NORTH, THERE IS
ONLY A SLIGHT CHANCE OF ANY ACTIVITY. ALL THE TAFS ARE VFR WITH SOME
CUMULUS EARLY AND THEN MID AND HIGH CLOUDS RECEDING SOUTHWARD TONIGHT.
MAINLY HIGH CLOUDS WITH PERHAPS A FEW CUMULUS ARE EXPECTED ON
FRIDAY. DRIER AIR IS EXPECTED TO MOVE DOWN FROM THE NORTH TONIGHT,
SO WE DON`T FORECAST ANY OVERNIGHT VISIBILITY RESTRICTIONS.
REGARDING WINDS, THE LATEST MODELS SHOW THEM PICKING UP FROM OUT OF
THE WEST EARLY IN THE TAF PERIOD WITH SOME GUSTS ABOVE 20 KT
POSSIBLE, THEN THEY SHOULD RELAX THIS EVENING BEFORE SHIFTING TO THE
NORTH OVERNIGHT THANKS TO A SECONDARY COLD FRONT. GENERALLY, WINDS
SHOULD BE RATHER GENTLE ON FRIDAY.
A SEA BREEZE HAD DEVELOPED AT ACY EARLIER TODAY, BUT WE THINK THE
STRENGTHENING WEST WIND WILL OVERWHELM IT EARLY IN THE TAF PERIOD. A
SEA BREEZE LIKELY WILL AFFECT ACY ON FRIDAY.
OUTLOOK...
FRIDAY NIGHT...MOSTLY VFR.
SATURDAY-SATURDAY NIGHT...MAINLY VFR WITH LOWERING CLOUDS. A
SLIGHT CHANCE OF SHOWERS AND SOUTH TO SOUTHEAST WINDS AROUND 5
KNOTS.
SUNDAY-SUNDAY NIGHT...GENERALLY VFR EXPECTED, POSSIBLE MVFR CIGS,
ESPECIALLY WITH ANY SHOWERS.
MONDAY-TUESDAY...GENERALLY VFR, POSSIBLE MVFR CIGS/VSBYS,
ESPECIALLY WITH ANY SHOWERS/THUNDERSTORMS.
&&
.MARINE...
ALTHOUGH WINDS WERE QUITE LIGHT OVER THE WATERS THIS AFTERNOON, A
RESURGENT SWELL ALONG THE FAR NORTHERN WATERS REQUIRED A SHORT-FUSED
ADVISORY FOR HAZARDOUS SEAS NORTH OF MANASQUAN INLET. MODELS SHOW
THE SWELL RETREATING BY THIS EVENING, AND THEN SEAS SHOULD BE
SUB-ADVISORY AND MORE OF A MIX OF DIMINISHING SWELLS AND MODEST TO
MODERATE WIND WAVES. THAT WILL BRING WINDS AND SEAS OVER ALL WATERS
BELOW ADVISORY CRITERIA THROUGH FRIDAY.
LIGHT WINDS THROUGH THIS EVENING ARE EXPECTED TO BECOME NORTHERLY
AND PICK UP SOME AS A SECONDARY COLD FRONT DROPS ACROSS THE COASTAL
WATERS OF NEW JERSEY AND DELAWARE. FORECAST PRESSURE RISES SUPPORT A
MODERATE BUT NOT ADVISORY LEVEL WIND. WINDS SHOULD DIMINISH AGAIN ON
FRIDAY. THE WINDS MAY BECOME ONSHORE NEAR LAND.
OUTLOOK...
CONDITIONS SHOULD REMAIN BELOW ADVISORY LEVELS THROUGH SATURDAY.
HOWEVER, WINDS MAY RETURN CLOSE TO ADVISORY LEVELS STARTING
SATURDAY NIGHT INTO SUNDAY AS THE PRESSURE GRADIENT TIGHTENS
ACROSS THE WATERS AS HIGH PRESSURE PUSHES OFF THE NORTHEAST COAST.
WITH THE EASTERLY/SOUTHEASTERLY FLOW, SEAS MAY RETURN TO SMALL
CRAFT ADVISORY LEVELS DUE TO THE LONG FETCH STARTING SUNDAY AND
CONTINUING INTO TUESDAY.
&&
.FIRE WEATHER...
WE WILL MENTION IN THE FIRE WEATHER FORECAST THAN MINIMUM RELATIVE
HUMIDITY LEVELS WILL DROP TO OR BELOW 30 PERCENT ON FRIDAY AFTERNOON
FOR MUCH OF THE FORECAST AREA. WINDS AND FINE FUELS ARE NOT A
CONCERN.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 PM EDT THIS
AFTERNOON FOR ANZ450.
&&
$$
SYNOPSIS...ROBERTSON
NEAR TERM...DELISI
SHORT TERM...DELISI
LONG TERM...ROBERTSON/YOUNG
AVIATION...DELISI/ROBERTSON
MARINE...DELISI/ROBERTSON
FIRE WEATHER...DELISI
AREA FORECAST DISCUSSION
NWS MIAMI FL
754 PM EDT FRI MAY 17 2013
.UPDATE...LITTLE CONVECTION DEVELOPED OVER LAND THIS AFTERNOON SO
HAVE REMOVED TSTORM MENTION ALL OF SOUTH FL THIS EVENING. ISOLATED
SHOWERS WILL CONTINUE OVER THE INTERIOR AND EAST COAST THIS
EVENING. OVERNIGHT, ISOLATED SHOWERS WILL CONTINUE OVER THE
ATLANTIC WITH MOVEMENT ONSHORE THE EAST COAST...PERHAPS WITH AN
INCREASE IN COVERAGE OVER THE ATLANTIC WATERS TOWARDS DAWN
SATURDAY AS PER THE HRRR. THERE CONTINUES TO BE A BOUNDARY EVIDENT
IN BOTH RADAR AND SATELLITE IMAGERY STRETCHING FROM NEAR THE COAST
AT SOUTHEASTERN PALM BEACH COUNTY EXTENDING EAST SOUTHEAST
BETWEEN GRAND BAHAMA ISLAND AND ANDROS. ISOLATED WATERSPOUTS ARE
POSSIBLE OVERNIGHT AND INTO SATURDAY MORNING ALONG THIS BOUNDARY,
SO WE WILL MENTION THIS IN THE HAZARDOUS WEATHER OUTLOOK UPDATE
THIS EVENING.
BEGINNING SATURDAY AND LASTING THROUGH MAY 24TH IS NATIONAL SAFE
BOATING WEEK. THE NATIONAL WEATHER SERVICE HAS PARTNERED WITH THE
NATIONAL SAFE BOATING COUNCIL TO HELP PROMOTE SAFE BOATING
PRACTICES. SATURDAY`S SAFETY THEME IS "LIFE JACKETS". "WEAR IT" TO
PLAY IT SAFE. 85% OF DROWNINGS FROM BOATING OCCURRED WHEN NO LIFE
JACKETS WERE WORN. /GREGORIA
&&
.AVIATION...
VFR CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD WITH A CHANCE OF
CEILING MVFR CONDITIONS ASSOCIATED WITH SPOTTY SHOWERS ACROSS THE
EAST COST TERMINALS OVERNIGHT AND INTO TOMORROW AFTERNOON. WINDS
WILL BECOME LIGHT FROM THE EAST AND SOUTHEAST OVERNIGHT (5 KNOTS OR
LESS) INCREASING TO THE 5 TO 10 KNOTS RANGE TOMORROW BY LATE MORNING
WITH A WEST COAST SEA BREEZE AT APF BY EARLY TO MID AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 229 PM EDT FRI MAY 17 2013/
DISCUSSION...
A WEAK AREA OF LOW PRESSURE REMAINS OVER SOUTH FLORIDA EARLY THIS
AFTERNOON...AND THIS FEATURE WILL DRIFT TO THE WEST AND PUSH OUT
INTO THE GULF OF MEXICO LATER TONIGHT. THIS WILL BRING SOME
SUBSIDENCE TO THE WESTERN HALF OF THE REGION...SO REMOVED THE POPS
FOR THE NAPLES AREA THIS AFTERNOON. SHOWERS THAT HAVE FORMED HAVE
HAD HIGH BASES...WHICH INDICATES THERE IS STILL DRY AIR IN THE LOW
LEVELS. WATER VAPOR IMAGERY INDICATES DRIER MID LEVEL AIR IS MOVING
IN FROM THE NORTHWEST...AND THE DRIER AIR IN THE LOW AND MID LEVELS
SHOULD PREVENT MANY...IF ANY THUNDERSTORMS THIS AFTERNOON. THE GFS
HAS BACKED OFF ON ANY SHOWERS THIS AFTERNOON...EXCEPT FOR PALM BEACH
COUNTY WHERE THEY WERE OCCURRING. THE HRRR STILL SHOWED ISOLATED TO
SCATTERED SHOWERS ALONG THE EAST COAST SEA BREEZE AFTER 20-21Z. SO
LEFT THE ISOLATED TO SCATTERED SHOWERS AND SLIGHT CHANCE OF THUNDER
WORDING. ANY SHOWERS OR STORMS THAT DEVELOP MAY CONTINUE INTO THE
EARLY EVENING BEFORE DISSIPATING.
AN UPPER RIDGE STRETCHING FROM TEXAS THROUGH THE NORTHERN PLAINS
WILL SLOWLY SHIFT EAST THROUGH THE WEEKEND. A WEAK SHORTWAVE WILL
DIVE SOUTHEAST SATURDAY AFTERNOON ACROSS FLORIDA IN THE
NORTHWESTERLY FLOW ALOFT. TEMPERATURES ALOFT ARE EXPECTED TO COOL TO
-10 TO -11C WITH 25-30 KNOTS OF 0-6KM BULK SHEAR. LAPSE RATES ALOFT
ARE NOT THAT IMPRESSIVE AND THERE IS STILL DRY AIR IN THE LOW/MID
LEVELS. HOWEVER...A COUPLE STRONG STORMS CANNOT BE RULED OUT ALONG
THE SEA BREEZE BOUNDARIES...MAINLY ACROSS THE INTERIOR. STORM MOTION
WILL BE DEPENDENT ON THE SEA BREEZE AND OUTFLOW BOUNDARIES. HIGHS ON
SATURDAY WILL BE NEAR NORMAL IN THE MID 80S TO LOWER 90S.
TEMPS WILL WARM ALOFT A BIT ON SUNDAY...AND SLIGHTLY DRIER AIR WILL
MOVE IN FROM THE EAST. SO THE EAST COAST SHOULD REMAIN MAINLY DRY
EXCEPT FOR POSSIBLY A FEW MORNING SHOWERS...WITH ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE INTERIOR AND GULF
COAST.
AN UPPER TROUGH WILL PUSH INTO THE INTERMOUNTAIN WEST ON SUNDAY AND
INTO THE NORTHERN PLAINS ON MONDAY...AND HIGH PRESSURE WILL SHIFT TO
THE EAST. THE LOW LEVEL FLOW WILL BEGIN TO SHIFT TO THE
SOUTHEAST...WITH SLIGHTLY DEEPER MOISTURE BEGINNING TO MOVE INTO THE
REGION. THE HIGHEST POPS WILL REMAIN OVER THE INTERIOR AND GULF
COAST. A WEAK UPPER TROUGH/LOW WILL PUSH SOUTHEAST INTO THE WESTERN
ATLANTIC BY SUNDAY AS IT GETS TRAPPED BENEATH A RIDGE OF HIGH
PRESSURE. THIS FEATURE IS EXPECTED TO THEN RETROGRADE SLOWLY TO THE
WEST SOUTHWEST THROUGH THE MIDDLE OF THE WEEK. IF THIS TROUGH MOVES
AS THE GFS INDICATES...DEEP SOUTHEASTERLY FLOW WOULD PREVAIL ON
TUESDAY...WITH TROPICAL MOISTURE MOVING INTO SOUTH FLORIDA. THE
ECMWF IS SLIGHTLY SLOWER AND PUSHES THE WEAK UPPER TROUGH/LOW OVER
DEEP SOUTH FLORIDA OR THE WESTERN GULF ON WEDNESDAY...DELAYING THE
DEEP MOISTURE UNTIL THAT TIME. EITHER WAY...IT APPEARS THAT DEEP
MOISTURE WILL MOVE OVER SOUTH FLORIDA BY THE MIDDLE OF THE WEEK AND
REMAIN THROUGH THE END OF THE FORECAST PERIOD.
AVIATION...
WEAK LOW PRESSURE NORTH OF KPBI FOCUSED SHOWERS THIS MORNING IN THAT
AREA, BUT WITH THE LOW MOVING TO THE NORTH THIS AFTERNOON, EXPECT
SHOWERS/ISOLATED TSTMS TO BE CONCENTRATED OVER THE INTERIOR WITH VFR
CONDITIONS AND VCSH FOR THE EAST COAST SITES. KAPF SHOULD SEE NO
MORE THAN A FEW CLOUDS WITH GULF SEA BREEZE THIS AFTERNOON. QUIET
NIGHT EXPECTED WITH ISOLATED SHOWERS AT WORST ALONG THE E COAST AND
PATCHY INLAND FOG. SE FLOW ON SATURDAY CONTINUING TO BRING IN A FEW
SHOWERS MAINLY E COAST WITH VFR PREVAILING.
MARINE...
THE WINDS WILL BE EASTERLY AROUND 10 KNOTS TONIGHT INTO THIS
WEEKEND. THIS WILL KEEP THE ATLANTIC AND GULF WATER SEAS AROUND 2
FEET THROUGH THE WEEKEND. SO BOATING CONDITIONS SHOULD BE GOOD
THROUGH THIS WEEKEND OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS THAT
DO DEVELOP OVER SOUTH FLORIDA WATERS.
FIRE WEATHER...
THE RELATIVE HUMIDITY OVER SOUTH FLORIDA WILL REMAIN ABOVE THE 35
PERCENT CRITICAL VALUE THROUGH THIS WEEKEND. DEEP MOISTURE WILL
RETURN TO THE REGION EARLY TO THE MIDDLE PART OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 85 75 85 / 20 30 20 20
FORT LAUDERDALE 76 86 77 86 / 20 20 20 20
MIAMI 75 87 76 86 / 20 20 20 20
NAPLES 71 88 71 89 / 10 20 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
335 AM EDT THU MAY 16 2013
.SYNOPSIS...
07Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS BROAD MID/UPPER LEVEL
RIDGING OVER THE SE CONUS AND FL PENINSULA EARLY THIS MORNING WHICH
WILL BE QUICKLY DE-AMPLIFYING THROUGH THE DAY/EVENING IN RESPONSE TO
THE APPROACH OF SHORTWAVE ENERGY EJECTING EASTWARD FROM THE SOUTHERN
PLAINS. THIS SHORTWAVE ENERGY WAS RESPONSIBLE FOR A SEVERE
WEATHER/TORNADO OUTBREAK ACROSS TEXAS THIS PAST EVENING...HOWEVER IT
WILL ENCOUNTER VERY DIFFERENT CONDITIONS AS IT PASSES BY OUR
REGION...AND IS LIKELY TO EXIT THE FORECAST AREA WITHOUT FANFARE.
16/00Z KTBW SOUNDING PROFILE SHOWED THE INFLUENCE OF THE UPPER RIDGE
WITH A WEAK SUBSIDENCE INVERSION AT THE TOP OF THE MIXING LAYER
AROUND 800MB. 800MB IS AROUND 7000KFT...SO VERY IMPRESSIVE MIXING ON
WEDNESDAY...ALTHOUGH NOT UNUSUAL FOR MAY. SKIES REMAIN MOSTLY CLEAR
ACROSS THE REGION OTHER THAN SOME PASSING THIN HIGH LEVEL CIRRUS
FROM TIME TO TIME. MORE IN THE WAY OF CLOUDS CAN BE SEEN TO OUR WEST
ACROSS THE CENTRAL GULF OF MEXICO WITHIN THE SYNOPTIC FORCING AHEAD
OF THE APPROACHING SHORTWAVE. SOME OF THIS MID/HIGH LEVEL CLOUDINESS
WILL BE CROSSING THE REGION LATER TODAY INTO THURSDAY...MAINLY OVER
CENTRAL/NORTHERN ZONES.
AT THE SURFACE...SUBTROPICAL RIDGE AXIS REMAINS STUCK IN PLACE FROM
OFF THE NE FLORIDA COAST BACK WESTWARD THROUGH THE NATURE COAST AND
INTO THE NE GULF OR MEXICO. THIS POSITION WILL REMAIN GENERALLY
UNCHANGED FOR THE NEXT SEVERAL DAYS...WITH PERHAPS A SLIGHT
NORTHWARD ADVANCEMENT OVER THE WEEKEND.
&&
.SHORT TERM (TODAY THROUGH SATURDAY)...
TODAY/TONIGHT...
LITTLE CHANGE IN FORECAST PHILOSOPHY OVER THE PAST 24 HOURS WITH
RESPECT TO THE FORECAST FOR THE FINAL TWO DAYS OF THE WORK WEEK.
MID/UPPER LEVEL RIDGE QUICKLY BREAKS DOWN TODAY AND IS SUPPRESSED
SOUTHWARD IN RESPONSE TO THE APPROACH AND ARRIVAL OF SHORTWAVE
ENERGY MOVING EASTWARD ALONG THE NORTHERN GULF COAST. OVERALL THIS
ENERGY WILL BEGIN TO SHEAR OUT AND BECOME MORE BROAD IN NATURE AS IT
NEARS THE NORTHERN PART OF FLORIDA. HOWEVER...THE OVERALL SYNOPTIC
FORCING OVERSPREADING THE REGION IS NOT ALL THAT WEAK...AND NORMALLY
WOULD BE EXPECTING ASSOCIATED SHOWER CHANCES. HOWEVER...THIS TIME
AROUND...COLUMN MOISTURE BELOW 500MB WILL SIMPLY BE LACKING...AND
THE ENVIRONMENT IS QUITE HOSTILE FOR CONVECTION TO BECOME ESTABLISH
WITH A DEEP LAYER (850-600MB) OF THETA-E VALUES BELOW 320K. WILL
CONTINUE TO LEAVE MENTION OF ANY SHOWERS OUT OF THE FORECAST. THE
ONLY REAL "IMPACT" WE SHOULD SEE FROM THIS PASSING ENERGY WILL BE A
BAND OF MID/HIGH LEVEL CLOUDS...AGAIN MAINLY OVER THE NORTHERN
ZONES. A FAVORABLE ENVIRONMENT SHOULD AGAIN ALLOW THE BOUNDARY LAYER
TO MIX UP TO AT LEAST 6KFT BY LATE AFTERNOON. 850-800MB TEMPS AROUND
14-15C WILL MIX DOWN EASILY INTO THE MIDDLE 80 INLAND WITH WARMER
SPOTS INTO THE UPPER 80S. SLIGHTLY COOLER AT THE BEACHES AS FLOW
TURNS ONSHORE FOR THE AFTERNOON. LOW TEMPERATURES TONIGHT ONLY DROP
TO THE LOWER 60S FOR THE COOLEST SPOTS.
FRIDAY/FRIDAY NIGHT...
SHORTWAVE AXIS WILL CROSS THE AREA DURING THE DAY AND EXIT TO OUR
EAST FRIDAY NIGHT. ENSEMBLE MODEL GUIDANCE STILL AGREES IN A SMALL
INCREASE IN OVERALL COLUMN MOISTURE FOR MOST SPOTS (OR AT LEAST A
THINNER LAYER OF SUPER DRY AIR) AND WILL KEEP A SLIGHT CHANCE 20%
POP IN THE GRIDS FOR AN AFTERNOON/EVENING SHOWER. THESE ISOLATED
SHOWERS WILL GENERALLY BE AWAY FROM THE BEACHES AS THE SEA-BREEZE
MAKES AT LEAST SOME INLAND PROGRESS. ANY CONVECTIVE CELLS WILL
HOWEVER STILL HAVE TO OVERCOME A GENERALLY HOSTILE THETA-E
ENVIRONMENT BETWEEN 5-15KFT. THIS HOSTILE ENVIRONMENT SHOULD KEEP
COVERAGE OF AFTERNOON CONVECTION LOW. TEMPERATURES WILL BE
SEASONABLE...WITH WARMER INLAND LOCATIONS REACHING THE LOWER 90 BY
MID/LATE AFTERNOON. OVERNIGHT LOWS FRIDAY NIGHT IN THE 60S INLAND
AND ALONG THE NATURE COAST AND AROUND 70 FOR TAMPA BAY SOUTHWARD
ALONG THE IMMEDIATE SUNCOAST.
SATURDAY...
A SUMMER-LIKE DAY APPEARS IN STORE FOR THE FIRST HALF OF THE
UPCOMING WEEKEND. MAIN SHORTWAVE WILL BE GONE TO OUR WEST...HOWEVER
THE MID/UPPER LEVEL PATTERN LEFT BEHIND IN ITS WAKE WILL REMAIN WEAK
OR "BAGGY" IN NATURE. THIS LACK OF SYNOPTIC SUPPRESSION ALONG WITH
AN INCREASINGLY FAVORABLE MOISTURE PROFILE SHOULD RETURN OUR
FORECAST TO CHANCE POPS (30-40%) DURING THE AFTERNOON/EARLY EVENING
HOURS. NOT LOOKING FOR A WET DAY BY ANY MEANS...BUT RATHER JUST A
MORE TYPICAL DISTRIBUTION OF BRIEF SEA-BREEZE CONVECTION. GOOD
MIXING AND 850MB BETWEEN 15-16C WILL HELP PUSH MANY SPOTS AWAY FROM
THE BEACHES INTO THE LOWER 90S. ENJOY!
&&
.LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)...
THE PERIOD BEGINS WITH AN UPPER LEVEL TROUGH FROM THE CANADIAN
ROCKIES TO THE FOUR CORNERS REGION...A RIDGE OVER THE WESTERN GULF
THAT REACHES NORTH TO THE UPPER MIDWEST...AND WEAK TROUGHING DOWN
THE EASTERN SEABOARD. THROUGH MID-WEEK THE WESTERN TROUGH DEEPENS
INTO A CLOSED LOW AS IT TRACKS EAST...TO THE MID WEST OR UPPER GREAT
LAKES...AND FLATTENS THE GULF RIDGE. MEANWHILE THE WEAK TROUGHING
CONTINUES ALONG OR JUST OFF THE EAST COAST AS IT SETTLES SOUTHWARD.
AT THE SURFACE...HIGH PRESSURE OVER THE ATLANTIC ALONG LATITUDE 30
NORTH...REINFORCED BY HIGH PRESSURE MOVING SOUTH FROM NEW ENGLAND
EARLY IN THE WEEK...RIDGES WEST ACROSS THE SE U.S. AND FL TO THE
CENTRAL GULF COAST DURING THE PERIOD.
THERE ARE SOME DIFFERENCES IN THE MODEL SOLUTIONS BUT THESE ARE
EXPECTED TO HAVE LIMITED IMPACT TO THE AREA...SO THE FORECAST
PHILOSOPHY CONTINUES WITH LITTLE CHANGE. A PREVAILING EAST AND SE
LOW LEVEL FLOW...BUT SLACK ENOUGH FOR AFTERNOON SEA BREEZES...
PROVIDES AMPLE MOISTURE WHICH ALONG WITH SEA BREEZE BOUNDARIES
AND A WEAK PATTERN ALOFT RESULTS IN SLIGHT CHANCE TO CHANCE
THUNDERSTORMS. THE TIMING WILL FAVOR MAINLY AFTERNOON AND EVENING.
TEMPERATURES WILL RUN NEAR NORMAL FOR THE LOWS WHILE
HIGHS WILL BE NEAR TO A DEGREE OR TWO ABOVE.
&&
.AVIATION...
VFR CONDITIONS THROUGH THE NEXT 24 HOURS WITH FEW TO SCT CLOUDS.
LIGHT EAST WINDS BECOME SE AFTER SUNRISE THEN TAKE ON A BAY/SEA
BREEZE COMPONENT DURING THE AFTERNOON.
&&
.MARINE...
THE SUBTROPICAL RIDGE AXIS WILL REMAIN IN PLACE ACROSS THE NORTHEAST
GULF OF MEXICO INTO THE UPCOMING WEEKEND. PATTERN THROUGH SATURDAY
WILL RESULT IN GENERALLY EAST TO WEST FLOW DURING THE OVERNIGHT AND
MORNING HOURS WITH THE FLOW THEN WEAKENING AND BECOMING VARIABLE FOR
THE AFTERNOON AND EVENING...WHILE ONSHORE SEA BREEZES DEVELOP NEAR
THE COAST. CHANCES FOR AN AFTERNOON OR EVENING THUNDERSTORM WILL
INCREASE DURING THE UPCOMING WEEKEND NEAR THE COAST...HOWEVER IT
CURRENTLY APPEARS THAT MOST OF THE STORMS SHOULD REMAIN A BIT
INLAND.
&&
.FIRE WEATHER...
SURFACE HIGH PRESSURE REMAINS IN CONTROL OF THE REGION THROUGH THE
UPCOMING WEEKEND. RELATIVE HUMIDITY WILL BRIEFLY APPROACH CRITICAL
LEVELS THIS AFTERNOON AND AGAIN ON FRIDAY AFTERNOON AWAY FROM THE
COAST...BUT EXTENDED DURATIONS OF THESE LOW RELATIVE HUMIDITY VALUES
ARE NOT EXPECTED...AND NO RED FLAG WARNINGS ARE REQUIRED. THE SLOW
INCREASE IN LOW LEVEL MOISTURE WILL CONTINUE INTO THE UPCOMING
WEEKEND AND SHOULD PREVENT ANY CRITICAL LEVELS OF RELATIVE HUMIDITY
FOR SATURDAY AND SUNDAY. THE FORECAST WILL ALSO SEE INCREASING
CHANCES FOR WIDELY SCATTERED AFTERNOON AND EVENING STORMS INTO THE
UPCOMING WEEKEND.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 87 69 88 72 / 0 0 10 10
FMY 89 67 90 71 / 10 10 20 20
GIF 88 66 91 67 / 0 0 20 10
SRQ 86 67 85 70 / 0 10 10 10
BKV 88 60 89 64 / 0 10 10 10
SPG 86 73 87 74 / 0 0 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA
LONG TERM/AVIATION/DECISION SUPPORT...RUDE
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1036 PM EDT FRI MAY 17 2013
.SYNOPSIS...
MOISTURE WILL INCREASE OVERNIGHT AND INTO SATURDAY AS AN UPPER-LEVEL
LOW SLOWLY APPROACHES THE REGION FROM THE WEST. THIS WILL BRING AN
INCREASING CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGH THE
WEEKEND. THE CHANCE FOR RAINFALL WILL CONTINUE INTO THE EARLY PART
OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AN INCREASE IN MOISTURE WILL OCCUR TONIGHT AHEAD OF THE MID-LEVEL
SHORTWAVE TROUGH. THE SHOWERS AND THUNDERSTORMS IN WESTERN GEORGIA
THIS EVENING MAY MOVE INTO THE FORECAST AREA DURING THE EARLY
MORNING HOURS TONIGHT. EXPECT COVERAGE WILL DIMINISH BECAUSE OF
DIURNAL COOLING. ALSO THE LATEST RAP INDICATES DEEPER MOISTURE
LIFTING NORTH OF THE FORECAST AREA. FORECASTED CHANCE POPS. THE
DIURNAL COOLING SHOULD ALSO FAVOR SHOWERS INSTEAD OF
THUNDERSTORMS. THE TEMPERATURE FORECAST APPEARS ON TRACK. EXPECT
LOWS IN THE MIDDLE 60S.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
THE BACKDOOR COLD FRONT WILL EDGE CLOSER TO THE NC/SC BORDER
SATURDAY. THE FRONT MAY STALL OUT NEAR THE NC/SC BORDER ON
SATURDAY...BUT COULD POSSIBLY SLIP INTO SC ON SUNDAY. ENERGY
ASSOCIATED WITH THE WEAK UPPER-LEVEL TROUGH MAY ALSO GIVE A
GREATER CHANCE FOR SHOWERS AND THUNDERSTORMS SATURDAY THROUGH
SUNDAY. CHANCE POPS LOOK REASONABLE THROUGH THE SHORT TERM.
FORECASTED TEMPERATURES CLOSE TO THE MOS CONSENSUS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE UPPER TROUGH WILL WEAKEN BUT STILL AFFECT THE REGION MONDAY.
THE UPPER RIDGE ATTEMPTS TO REBUILD OVER THE SOUTHEAST WHICH WILL
KEEP A WARM AND GENERALLY MOIST AIR MASS OVER THE AREA FOR MUCH OF
THE WEEK...ALTHOUGH AREAL COVERAGE MAY BE A BIT LESS THAN EARLY IN
THE WEEK. EXPECT MAINLY DIURNAL SHOWERS AND THUNDERSTORMS TUESDAY
THROUGH FRIDAY. HIGH CHANCE POPS MONDAY...WITH LOWER CHANCE POPS
FOR THE REMAINDER OF THE MEDIUM-RANGE PERIOD. EXPECT TEMPERATURES
CLOSE TO OR JUST ABOVE CLIMATOLOGY THROUGH THE PERIOD.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
SCATTERED MID AND HIGH CLOUDS OVER THE AREA WILL INCREASE OVERNIGHT
FROM THE WEST AS AN UPPER DISTURBANCE MOVING ACROSS ALABAMA SHIFTS
EASTWARD TOWARD THE AREA. DESPITE LIGHT TO CALM WINDS THIS
EVENING...A LOW LEVEL JET IS FORECAST LATER TONIGHT WHICH SHOULD
KEEP WINDS FROM STAYING CALM AND THE INCREASE IN CLOUDS SHOULD LIMIT
THE FOG POTENTIAL. HOWEVER...OGB COULD HAVE A COUPLE OF HOURS OF
TEMPORARY MVFR VSBYS IN FOG BEFORE THE CLOUDS THICKEN. AGS ALREADY
HAS A 4 DEGREE TEMP DEWPOINT SPREAD AND COULD SEE SOME FOG BEFORE
THE THICKER CLOUDS ARRIVE SO WILL INCLUDE TEMPORARY RESTRICTIONS TO
VSBY THERE 05Z-09Z.
AFTER 12Z...MID AND HIGH CLOUDS ARE EXPECTED TO BE OVER THE REGION
BUT ENOUGH SURFACE HEATING COMBINED WITH SOME WEAK UPPER SUPPORT
COULD TRIGGER ISOLATED DIURNAL CONVECTION. PROBABILITIES AND
CONFIDENCE IN LOCATION AND TIMING ARE UNCERTAIN AND THEREFORE WILL
NOT INCLUDE THUNDER OR ANY RESTRICTIONS AT THIS TIME. WINDS WILL
GENERALLY BE FROM THE SOUTH LESS THAN 10 MPH.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS
SUNDAY THROUGH THE EARLY PART OF NEXT WEEK.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
830 PM CDT FRI MAY 17 2013
.DISCUSSION...
ISSUED 830 PM CDT FRI MAY 17 2013
01Z/8PM RADAR IMAGERY SHOWS ISOLATED SHOWERS ALONG/NORTHWEST OF A
PETERSBURG TO BLOOMINGTON-NORMAL LINE. THESE SHOWERS WILL CONTINUE
TO DRIFT SLOWLY NORTHWARD BEFORE DISSIPATING BY AROUND 10PM. AFTER
THAT...DRY WEATHER IS ANTICIPATED OVERNIGHT. WITH MOIST DEWPOINTS
IN THE LOWER TO MIDDLE 60S AND VERY LIGHT WINDS...EXPECT FOG TO
DEVELOP AFTER MIDNIGHT. HRRR SUGGESTS VISBYS MAY DROP TO 1SM OR
LESS TOWARD DAWN...HOWEVER THINK THIS MAY BE A BIT TOO AGGRESSIVE
GIVEN THE AMOUNT OF CLOUD COVER THAT SHOULD BE STICKING AROUND. AT
THIS POINT...WILL JUST CARRY PATCHY FOG OVERNIGHT. ZONE UPDATE HAS
ALREADY BEEN ISSUED.
BARNES
&&
.AVIATION...
ISSUED 644 PM CDT FRI MAY 17 2013
SCATTERED SHOWERS WILL CONTINUE TO DEVELOP AND DRIFT NORTHWARD
OVER THE NEXT COUPLE OF HOURS...BEFORE DISSIPATING AFTER SUNSET.
WILL CARRY VCSH AT ALL TERMINALS BETWEEN 00Z AND 03Z ACCORDINGLY.
WITH LIGHT WINDS AND PLENTY OF LOW-LEVEL MOISTURE IN
PLACE...PARTIAL CLEARING OVERNIGHT WILL LEAD TO THE DEVELOPMENT OF
PATCHY FOG. BIG QUESTION WILL BE WHETHER OR NOT A LOW OVERCAST
WILL FORM AS WELL. NAM FORECAST SOUNDINGS ARE SUGGESTING CEILINGS
OF AROUND 1000FT OVERNIGHT INTO EARLY SATURDAY MORNING. THINK THIS
IS OVERDONE AND WILL ONLY INCLUDE SCT CLOUD COVER AROUND 1500FT
ALONG WITH 2-4SM FOG OVERNIGHT. ONCE THE MORNING FOG/CLOUDS
LIFT...NEGATIVE CU-RULE POINTS TO A PARTLY SUNNY DAY WITH CLOUD
BASES AROUND 5000FT. WINDS WILL INITIALLY BE SOUTHERLY EARLY THIS
EVENING...THEN WILL BACK TO E/SE LATER TONIGHT INTO SATURDAY
BARNES
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT FRI MAY 17 2013
AN EXTENDED PERIOD OF RAIN CHANCES WILL CONTINUE INTO THE WEEKEND
AND MOST OF NEXT WEEK. THE MAIN WEATHER FEATURES WILL BE A
STATIONARY FRONT AND UPPER LOW THE REST OF TODAY AND
SATURDAY...THEN A WARM FRONT ACROSS IL AND DEEPENING LOW PRESSURE
IN THE PLAINS ON SUNDAY AND MONDAY...THEN A SLOW MOVING OCCLUDED
LOW MONDAY NIGHT THROUGH TUESDAY NIGHT...BEFORE A COLD FRONT
FINALLY PUSHES ACROSS ILLINOIS ON WEDNESDAY.
THE BEST WINDOW OF OPPORTUNITY FOR ANY LONGER BREAKS IN THE RAIN
MAY BE SATURDAY AND SUNDAY...BUT STRONG INSTABILITY AS THE CAP
ERODES LATE SUNDAY AFTERNOON INTO SUNDAY EVENING MAY ALLOW FOR
STRONG TO SEVERE STORMS SUNDAY NIGHT NORTHWEST OF THE IL RIVER.
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT.
SHOWERS AND THUNDERSTORMS ERUPTED THIS AFTERNOON AS THE CAP
DISSIPATED...BUT COVERAGE WAS ISOLATED FOR THE MOST PART. THE
PRIMARY AREA OF ACTIVITY IN OUR AREA WAS FROM GALESBURG TO
HOOPESTON...CLOSER TO THE STATIONARY FRONT THAT EXTENDED ACROSS
NORTHERN IL. ADDITIONAL SHOWERS DEVELOPED FARTHER SOUTH FROM
JACKSONVILLE TO LAWRENCEVILLE ASSOCIATED WITH THE UPPER LOW MOVING
EAST INTO KENTUCKY. THE FRONT AND LOW WILL CONTINUE TO TRIGGER
SHOWERS AND STORMS INTO THE EVENING...BUT PROGRESSIVELY EAST WITH
TIME. BY MIDNIGHT...WE EXPECT PRECIP TO COME TO AN END IN CENTRAL
IL.
MOST OF THE DAY ON SATURDAY SHOULD BE DRY...BUT WE CAN NOT RULE
OUT SOME DIURNAL SHOWERS AND ISOLATED STORMS EAST OF I-57 AS THE
UPPER LOW LINGERS NEARBY TO THE EAST OF IL. A LULL IN THE RAIN
LOOKS LIKELY SATURDAY NIGHT AND MUCH OF SUNDAY...AS WARM AIR
SURGES INTO THE AREA. DEWPOINTS ON SUNDAY WILL CLIMB INTO THE
LOWER 70S AS HIGH TEMPS REACH THE UPPER 80S. A LOW LEVEL INVERSION
WILL PROVIDE A CAP UNTIL LATE IN THE DAY ON SUNDAY. ELEVATED
INSTABILITY WILL INCREASE DRAMATICALLY BY LATE AFTERNOON...WITH ML
CAPE VALUES AROUND 4K J/KG AND LI`S OF -10C. THE CAP WILL ERODE
FROM WEST TO EAST...REACHING PEORIA TO SPI BY 6-7 PM. SO OUR
WESTERN COUNTIES WILL HAVE THE BEST CHANCES FOR STRONG TO SEVERE
STORMS SUNDAY EVENING. TONED DOWN STORMS ARE EXPECTED TO ADVANCE
EAST TOWARD I-57 AFTER MIDNIGHT SUNDAY NIGHT.
MONDAY LOOKS TO BE LESS LIKELY FOR STORMS THAN PREVIOUS FORECAST
MODEL SOLUTIONS INDICATED. CLOUD COVER WILL KEEP HIGH TEMPS IN THE
LOWER 80S...BUT WE WILL REMAIN IN THE WARM SECTOR. WE REMOVED ANY
LIKELY POPS FROM MONDAY AND KEPT CHANCE POPS ACROSS THE AREA.
INSTABILITY PARAMS BECOME FAVORABLE AGAIN FOR STRONG STORMS MONDAY
EVENING...AS WE BREAK THE INVERSION AGAIN...BUT WE ARE NOT IN THE
SPC DAY 4 OUTLOOK FOR MON-MON NIGHT LIKE WE WERE IN THE DAY 5
OUTLOOK YESTERDAY. LACK OF A SOLID FOCUSING MECHANISM IS ONE OF
THE REASONS WHY. THE WARM FRONT WILL BE NORTH OF OUR AREA...AND
THE OCCLUDED LOW AND ITS ENERGY WILL BE MAINLY IN THE NORTHERN
PLAINS.
LONG TERM...TUESDAY THROUGH FRIDAY.
AS THE OCCLUDED LOW MOVES TOWARD IL ON TUESDAY...AND SETTLES OVER
N-NW IL TUESDAY NIGHT COVERAGE OF SHOWERS AND STORMS WILL BECOME
MORE WIDESPREAD. LIKELY POPS WERE INCLUDED EVERYWHERE BUT THE FAR
WESTERN COUNTIES TUESDAY AND TUESDAY NIGHT...WITH LOCALLY HEAVY
RAINFALL POSSIBLE AS STORM MOTIONS REMAIN SLOW.
THE COLD FRONT WILL EVENTUALLY MOVE ACROSS OUR AREA ON WEDNESDAY
AS THE LOW PRESSURE SYSTEM FINALLY PULLS AWAY TO THE NORTHEAST.
DRIER CONDITIONS WILL BEGIN TO RETURN WED NIGHT...BUT THE COLD
POOL ALOFT WILL KEEP CHANCES OF INSTABILITY SHOWERS IN PLACE FOR
THURSDAY.
THE COLDEST AIR OF THE WEEK WILL COME THURSDAY THROUGH FRIDAY...AS
HIGHS ONLY REACH THE LOW TO MID 70S...AND LOWS DIP INTO THE 50S.
SUNSHINE AND DRY CONDITIONS RETURN FOR FRIDAY...FINALLY.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
311 PM CDT THU MAY 16 2013
.DISCUSSION...
ISSUED 300 PM CDT THU MAY 16 2013
A STATIONARY FRONT WILL OSCILLATE NORTH AND SOUTH ACROSS ILLINOIS
OVER THE NEXT DAY AND A HALF...THEN THE FRONT SHOULD LIFT NORTH AS
A WARM FRONT FOR THE WEEKEND...PUSHING HIGHS INTO THE MID TO UPPER
80S BY SUNDAY. BANDS OF THUNDERSTORMS THAT DEVELOP THROUGH
TOMORROW WILL LIKELY BE SLOW MOVING, HEAVY RAIN PRODUCERS LIKE
TODAY`S STORMS. LOCALIZED AREAS COULD SEE SIGNIFICANT RAINFALL OF
2-3 INCHES IN A COUPLE HOURS WHILE NEARBY AREAS SEE LITTLE RAIN.
PINPOINTING THAT ACTIVITY WILL BE DIFFICULT...BUT DIURNAL TRENDS
SHOULD PUT MOST OF THE CONVECTION DURING THE AFTERNOON
TOMORROW...ESPECIALLY NEAR ANY OUTFLOW BOUNDARIES SET DOWN BY
TODAY`S STORMS.
A SLIGHT LULL IN STORMS SHOULD OCCUR THIS WEEKEND AS RIDGING IN
THE PLAINS BUILDS INTO IL. A STRONGER COLD FRONT IS EXPECTED TO
PUSH ACROSS IL ON MONDAY AND MONDAY NIGHT...BRINGING OUR BETTER
CHANCES OF THUNDERSTORMS. WE ARE IN THE SPC DAY 5 OUTLOOK FOR
STRONG TO SEVERE STORMS MON-MON NIGHT. A COOL DOWN IS PROJECTED
FOR TUES THROUGH THURSDAY BEHIND THE COLD FRONT...PULLING HIGHS
BACK INTO THE 70S...BUT STILL AT OR ABOVE NORMAL.
SHORT TERM...TONIGHT THROUGH SUNDAY.
SHOWERS AND STORMS WILL GENERALLY BE DIMINISHING AS WE HEAD INTO
THE EVENING. THE LINE OF CONVECTION MAINLY CENTERED ON A LINE
FROM RUSHVILLE TO TAYLORVILLE TO EFFINGHAM TO LAWRENCEVILLE...IS
EXPECTED TO LIFT NORTH THIS EVENING. THE RAP MODEL IS SHOWING THE
INSTABILITY AXIS FOLLOWING THE SAME PROGRESSION...WITH SOME SHOWER
ACTIVITY DEVELOPING DURING THAT TIME. IN THE LAST HOUR...PRECIP
COVERAGE AND UPDRAFT INTENSITY HAVE ALREADY BEGUN DIMINISHING OR
WEAKENING RESPECTIVELY. RADAR LOOPS SHOW VARIOUS OUTFLOW
BOUNDARIES MOVING NORTH ACROSS OUR COUNTIES...AND MAY END UP BEING
A FOCUS FOR EVENING SHOWERS ALONG AND NORTH OF I-72.
STILL...COVERAGE WILL BE ISOLATED IN GENERAL.
FRIDAY MORNING...THE LOCATION OF THE BEST INSTABILITY WILL BE
ALONG AND NORTH OF I-74...SO ANY MORNING CONVECTION ON FRIDAY MAY
BE FOCUSED IN THAT AREA. DURING THE AFTERNOON...AN UPPER LOW
PRESSURE WAVE IS FORECAST TO LIFT NORTHEAST ACROSS IL...IN CONCERT
WITH INCREASING MOISTURE AND INSTABILITY AS THE STATIONARY FRONT
OSCILLATES NORTHWARD WITH THE WAVE. COVERAGE OF STORMS SHOULD BE
MORE THAN TODAY...BASED ON THE SUPPORT OF THE UPPER WAVE AND JET
DYNAMICS. ANY SUNSHINE THAT HEATS UP THE BOUNDARY LAYER WILL HELP
TO CREATE A FEW STRONG UPDRAFTS WITH SMALL HAIL, GUSTY WINDS, AND
VERY HEAVY RAINFALL.
THE STORMS MAY LINGER INTO THE EVENING EAST OF I-57...BUT SHOULD
DIMINISH BY MIDNIGHT. BY 12Z SAT MORNING...THE UPPER LOW IS
FORECAST TO BE CENTERED IN SOUTHERN INDIANA...WHICH WILL HELP PUT
PRECIP CHANCES MAINLY IN OUR SOUTHEAST COUNTIES ALONG AND SOUTHEAST
OF A LINE FROM SHELBYVILLE TO PARIS. THE SLOW DEPARTURE OF THE LOW
WILL KEEP CHANCES OF SHOWERS AND STORMS THROUGH SATURDAY AFTERNOON
IN THE SOUTHEAST.
THE WARM FRONT DEPARTING INTO NORTHERN IL FOLLOWED BY RIDGING AT
THE SURFACE AND ALOFT SATURDAY NIGHT AND SUNDAY SHOULD HELP MAKE
MOST AREAS DRY FOR THE LAST HALF OF THE WEEKEND. THE ADDITIONAL
SUNSHINE ON SUNDAY ALONG WITH DEEPER WARM AIR WILL HELP PUSH HIGH
TEMPS INTO THE MID TO UPPER 80S...WITH MUGGY DEWPOINTS IN THE
UPPER 60S TO NEAR 70. HEAT INDEX READINGS SUNDAY AFTERNOON WILL
CLIMB INTO THE 90S.
LONG TERM...MONDAY THROUGH THURSDAY.
ON MONDAY...AN OCCLUDING LOW PRESSURE PRESSURE SYSTEM IN THE
EASTERN DAKOTAS WILL CREATE SOME WARM FRONTOGENESIS TO THE
SOUTHEAST OF THE LOW ACROSS OUR NORTHERN COUNTIES. THAT WILL
CREATE A FOCUS FOR CONVECTION BY MONDAY AFTERNOON. MONDAY
NIGHT...A COLD FRONT WILL MOVE ACROSS IL PRODUCING STRONG TO
SEVERE STORMS AS ML-CAPE VALUES CLIMB TO NEAR 2K J/KG. BULK SHEAR
IS EXPECTED TO REACH OVER 40KT AS WELL...SO EMBEDDED SUPERCELLS
WILL BE POSSIBLE IN THE LINE OF STORMS THAT MOVES THROUGH.
STORMS ARE EXPECTED TO LINGER INTO TUESDAY AS THE UPPER COLD POOL
SLOWLY MAKES PROGRESS INTO ILLINOIS. WE KEPT LIKELY POPS SOUTHEAST
OF I-72...AND CHANCE ELSEWHERE. TUESDAY NIGHT PRECIP COVERAGE
SHOULD DIMINISH...WITH CHANCE POPS STILL IN PLACE ACROSS THE
BOARD. AN ELONGATED SURFACE TROUGH IS PROJECTED TO LINGER ACROSS
NORTHERN ILLINOIS INTO WED AS THE OCCLUDED UPPER LOW BECOMES MORE
OF AN OPEN WAVE AND SEND A SURFACE LOW EASTWARD ACROSS WISCONSIN.
THAT PROGRESSION WILL KEEP SCATTERED SHOWERS POSSIBLE AS FAR
SOUTH AS CENTRAL ILLINOIS THROUGH THURSDAY...ESPECIALLY EAST OF
I-55. PRECIP AMOUNTS MID WEEK SHOULD REMAIN LIGHT...BUT STILL
CLOUDS AND COOLER AIR WILL KEEP HIGH TEMPS BACK IN THE
70S...CLOSER TO NORMAL.
SHIMON
&&
.AVIATION...
ISSUED 1225 PM CDT THU MAY 16 2013
POP-UP NATURE OF SHOWERS/STORMS THIS AFTERNOON WILL BE A CHALLENGE
IN GOING WITH ANYTHING MORE THAN VCTS. ONE LINE OF STORMS WAS
LOCATED JUST SOUTH OF KSPI/KTAZ BUT REMAINING STATIONARY...SO WILL
NOT ADD A PREVAILING TSRA AT KSPI YET. MANY OF THE STORMS SHOULD
FADE WITH SUNSET...AND HAVE GONE WITH LARGELY DRY CONDITIONS AT
ALL TAF SITES MUCH OF THE NIGHT. LATEST HIGH- RESOLUTION GUIDANCE
SUGGESTING SOME LATE NIGHT DEVELOPMENT NEAR KPIA/KBMI...AND HAVE
PUT SOME VCTS BACK THERE...ALTHOUGH MAIN CONCERN LATE NIGHT WILL
BE WITH AREAS OF MVFR FOG. ON FRIDAY MORNING...POTENTIAL EXISTS
FOR ADDITIONAL SHOWERS/STORMS TO LIFT UP FROM THE SOUTH...AND HAVE
MENTIONED VCTS AT KSPI/KDEC AFTER 15Z.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1143 PM CDT WED MAY 15 2013
.DISCUSSION...
ISSUED 837 PM CDT WED MAY 15 2013
STATIONARY FRONTAL BOUNDARY BISECTS CENTRAL ILLINOIS THIS
EVENING...WITH COOLER/SLIGHTLY DRIER AIR FILTERING INTO THE FAR
NORTHERN KILX CWA WHERE DEWPOINTS HAVE DROPPED INTO THE UPPER 40S
AND LOWER 50S. FURTHER SOUTH...MOISTURE POOLING ALONG THE BOUNDARY
HAS RESULTED IN DEWPOINTS IN THE LOWER 60S ALONG THE I-72
CORRIDOR. 01Z/8PM IR SATELLITE IMAGERY IS BEGINNING TO SHOW AC
DEVELOPING ALONG THE FRONT...WITH REGIONAL RADAR SHOWING SCATTERED
THUNDERSTORMS DEVELOPING FURTHER WEST ACROSS NORTHERN MISSOURI.
23Z HRRR SUGGESTS CONVECTION WILL DEVELOP EASTWARD ALONG THE
FRONT INTO WEST-CENTRAL ILLINOIS AFTER 03Z/10PM. BASED ON POSITION
OF FRONT AND LATEST HIGH-RES MODEL DATA...HAVE LOWERED POPS TO
JUST SLIGHT CHANCE ACROSS THE SE CWA ALONG/SOUTH OF I-70. FURTHER
NORTH...WENT WITH SCATTERED WORDING ACROSS THE CENTRAL AND
NORTHERN ZONES IN CLOSER PROXIMITY TO THE BOUNDARY. ALSO ADJUSTED
OVERNIGHT LOWS UP A FEW DEGREES...WITH LOWER TO MIDDLE 60S IN MOST
LOCATIONS...EXCEPT COOLER UPPER 50S FAR NORTH. ZONE UPDATE HAS
ALREADY BEEN ISSUED.
&&
.AVIATION...
ISSUED 1142 PM CDT WED MAY 15 2013
STATIONARY FRONTAL BOUNDARY CURRENTLY DRAPED ACROSS THE AREA WILL
BE THE MAIN FOCUSING MECHANISM FOR WIDELY SCATTERED SHOWERS/THUNDER
THROUGH THE ENTIRE 06Z TAF PERIOD. LATEST RADAR IMAGERY SHOWS
SCATTERED CONVECTION IMMEDIATELY AHEAD OF THE FRONT SOUTH OF THE
I-72 CORRIDOR...WITH ANOTHER BROKEN LINE OF SHOWERS/STORMS
DEVELOPING FURTHER NORTH ALONG THE UPPER-LEVEL FRONT FROM THE
PEORIA AREA WESTWARD. SINCE NO TERMINAL IS IMMEDIATELY THREATENED
BY CONVECTION AT THIS TIME...WILL JUST CARRY VCTS ACROSS THE
BOARD. MODEL SOLUTIONS VARY OVERNIGHT...HOWEVER BOTH THE NAM AND
HRRR STILL SUGGEST A DIMINISHING TREND...WHICH WILL BE FOLLOWED
FOR THIS FORECAST ISSUANCE. WILL THEREFORE END THUNDER MENTION
AFTER 09Z. SCATTERED SHOWERS/THUNDER WILL RE-DEVELOP ON THURSDAY
AS THE FRONT BEGINS TO SLOWLY LIFT BACK NORTHWARD. WILL BRING VCTS
BACK INTO THE FORECAST AT KSPI AND KDEC AFTER 14Z...SPREADING
NORTH TO KPIA BY 20Z. WINDS WILL INITIALLY BE LIGHT/VARIABLE
TONIGHT INTO THURSDAY MORNING...THEN WILL BECOME SOUTHERLY BY
AFTERNOON AND EVENING AS THE FRONT SHIFTS NORTHWARD.
BARNES
&&
.PREV DISCUSSION...
ISSUED 259 PM CDT WED MAY 15 2013
FORECAST CONCERN TODAY IS THE POPS ASSOCIATED WITH THE STALLING
FRONT OVER THE REGION INTO THE WEEKEND...AND THEN THE APPROACH OF
THE MAIN UPPER WAVE AND FRONT THE FIRST PART OF NEXT WEEK.
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT.
MORNING UPPER AIR DATA AND SPC INSTABILITY ANALYSIS SHOWS THE
EAST-WEST FRONTAL ZONE HAD MADE INTO THE NORTH CENTRAL PART OF IL
TODAY...WITH ENOUGH CONVERGENCE ON THE BOUNDARY TO CONTINUE THE
TREND THAT BEGAN OVERNIGHT...OF ELEVATED CONVECTION FORMING AND
MOVING EAST ALONG THE FRONTAL ZONE. THIS TREND HAS BEEN THE CASE
ALL DAY...AS THE UPPER AIR SHOWED A TONGUE OF LOW LEVEL MOISTURE
SURGING NORTH FROM TX OVER MO INTO THE BOUNDARY ZONE. SPC MESODATA
CONTINUED TO SHOW AIR SOUTH OF THE BOUNDARY CAPPED AND THE PCPN
REMAINING ELEVATED. EXPECT THIS TREND TO REMAIN OVERNIGHT...WITH
THE FRONT SAGGING A LITTLE SOUTH.
WITH THE FRONT PROGGED TO BE IN THE REGION BY ALL THE MODELS ON
THURSDAY...WILL KEEP POPS IN THE LIKELY CAT THROUGH CENTRAL REGION.
ADDITIONAL SUPPORT FOR DEVELOPMENT WITH UPPER LEVEL REMAINS OF THE
WEAKENING UPPER WAVE THAT IS OVER TX TODAY. THAT SYSTEM WILL BE
DRIFTING TO THE EAST NORTHEAST OVER OK TO AR. THIS SYSTEM IS
FORECAST TO WASH OUT THURSDAY NIGHT AND THEN THE UPPER RIDGE
BEGINS TO START TO BUILD OVER AREA. LOWERING POPS THEN FRIDAY AND
INTO FRIDAY NIGHT.
.LONG TERM...SATURDAY THROUGH WEDNESDAY.
THE APPROACH OF THE DEEPENING UPPER LOW/WAVE ON SUNDAY GRADUALLY
INCREASES POPS OVER WEST SUNDAY. GFS AND NEW EUR ARE DIFFERENT IN
THE DETAILS ON THE APPROACHING FRONT AND THE UPPER LOW/TROUGH
CONFIGURATION. TODAYS RUN DOES NOT DISPLAY A CLEAR SYSTEM MOVING
THROUGH...BUT A MORE GRADUAL MOVEMENT OF THE UPPER SYSTEM...WHICH
RESULTS IN A LONGER PERIOD OF POPS...FOR SUNDAY INTO THE DAY
WEDNESDAY. WILL STILL HAVE TO WATCH MONDAY FOR SIGNIFICANT
CONVECTION...AS SOUNDING AND HODOGRAPH ON THAT DAY STILL SHOW
POTENTIAL FOR STRONG STORMS.
GOETSCH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
659 PM EDT THU MAY 16 2013
.SYNOPSIS...
ISSUED AT 655 PM EDT THU MAY 16 2013
A FRONTAL BOUNDARY WHICH HAS BROUGHT SHOWERS AND THUNDERSTORMS TO
PORTIONS OF SOUTHERN INDIANA AND OHIO TODAY WILL BEGIN TO SHIFT
NORTH BY FRIDAY AFTERNOON WHICH WILL BRING A LOW CHANCE OF SHOWERS
AND THUNDERSTORMS TO AREAS SOUTH OF US 30. SHOWER AND THUNDERSTORM
CHANCES WILL PERSIST THROUGH THE WEEKEND AS THE FRONTAL BOUNDARY REMAINS
ACROSS THE AREA. ABOVE NORMAL TEMPERATURES ARE EXPECTED LATE THIS
WEEK INTO THIS WEEKEND. CHANCES FOR SHOWERS AND THUNDERSTORMS
INCREASE EARLY NEXT WEEK AS A STORM SYSTEM APPROACHES FROM THE
WEST.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
HIGH PRESSURE HAS KEPT BULK OF MSTR JUST FAR ENOUGH SOUTH OF THE
AREA TODAY TO ALLOW FOR GENERALLY DRY CONDITIONS AND TEMPS MOVING
WELL THROUGH THE 70S IN MOST SPOTS. A FEW LIGHT SHOWERS/SPRINKLES
WERE NOTED ALONG FIRST OF 2 SFC THETA E GRADIENTS ACROSS FAR
SOUTHERN COUNTIES. THIS AREA IS EXPECTED TO SHIFT SOUTH OVER THE
NEXT SEVERAL HOURS AND REMOVE ANY CHANCE FOR PRECIP FOR THE
REMAINDER OF THE NIGHT. SECONDARY GRADIENT WAS LOCATED FURTHER
SOUTH ACROSS SOUTHERN INDIANA WHERE CONVECTION HAS BEEN ONGOING
MUCH OF THE DAY. MODELS TEND TO SUGGEST THAT THIS SECONDARY AREA
OF MSTR/GREATER LIFT SUPPORT WITH MAIN SFC BOUNDARY WILL BRING
INCREASING CHANCES FOR SHOWERS AND STORMS ON FRIDAY. IT WOULD
APPEAR THAT MOST FAVORABLE TIMING WOULD BE MID TO LATE AFTERNOON
FRIDAY IN FAR SW SECTIONS WITH PROGRESSION NE HAMPERED SOMEWHAT BY
DRY AIR/SEMI DRY GROUND CONDITIONS. IF NEW RUN OF SPC 4KM WRF IS
FOLLOWED...CONVECTION WOULD NOT ARRIVE UNTIL AFTER 00Z SAT. HAVE
ADJUSTED GRIDS TO REFLECT THIS WITH SLGT CHC TO CHC POPS CONFINED
TO AFTERNOON.
CLOUD COVER WILL BE ON THE INCREASE...WHICH WILL BUT A DAMPER ON
POTENTIAL CLIMB IN HIGHS. THAT BEING SAID...HIGHS SHOULD STILL END
UP ABOVE NORMAL CLIMBING INTO THE MID AND UPPER 70S.
&&
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
WATER VAPOR IMAGERY AND LATEST RAP ANALYSIS THAT IS DEPICTING MID
LEVEL CIRCULATION MOVING EASTWARD ACROSS THE SOUTHERN PLAINS THIS
AFTERNOON WILL HAVE AN IMPACT ON THE BEGINNING OF THE EXTENDED
FCST PERIOD AS IT MOVES ACROSS THE TN VALLEY. THIS WILL ACT ON
STATIONARY SFC BOUNDARY IN ADVECTING MOISTURE IN AN OVERRUNNING
FASHION BACK NORTH OF THE BOUNDARY AND LEND SUPPORT TO WIDELY
SCATTERED CONVECTION OVER THE SW HALF OF THE CWA. FOCUS WILL THEN
SHIFT TO AMPLIFICATION OF THE UPPER LEVEL PATTERN AS STRONG JET
DYNAMICS CURRENTLY WELL OUT IN THE PACIFIC ARE PROGGED BY MEDIUM
RANGE MODELS TO COME ONSHORE AND DEVELOP DEEP UPPER TROF OVER THE
WESTERN US. THIS WILL INDUCE DOWNSTREAM RIDGING THAT WILL BUILD
INTO THE REGION SUN/MON BRINGING WARMER AND MAINLY DRY CONDITIONS
TO THE AREA. WESTERN CONUS UPPER TROF THEN EXPECTED TO BECOME
VERTICALLY STACKED CLOSED SYSTEM IN THE NORTHERN PLAINS WHICH
MODELS ARE STRUGGLING WITH TIMING OF THE EVENTUAL EJECTION OF THIS
SYSTEM INTO OUR AREA. AS EXPECTED OVERALL TREND CONTINUES TO BE
SLOWER WITH ARRIVAL OF MAIN SYSTEM NOW DELAYED TO TUE/WED
TIMEFRAME AND BRINGING WITH IT THE BEST CHANCES FOR PRECIP. PRIOR
TO ITS ARRIVAL...BECOMING MORE AND MORE DIFFICULT TO PICK OUT
MODELS HANDLING OF INCREASINGLY DIFFUSE SFC BOUNDARY BUT
INDICATIONS ARE BOUNDARY WILL LIFT NORTH OF THE AREA IN
CONJUNCTION WITH UPPER RIDGE MOVING OVER THE AREA WHICH SHOULD
LEAVE MUCH OF THE FORECAST AREA IN A CAPPED WARM SECTOR SUN/MON.
LOW CONFIDENCE IN ANY ONE PARTICULAR SCENARIO WITH THIS SETUP BUT
WILL STILL INJECT A PERIOD OR TWO OF DRY WEATHER TO REFLECT THIS.
ANTICIPATE TEMPS WELL INTO THE 80S ON MONDAY DEPENDING ON AMOUNT
OF SUN...BUMPED ALLBLEND UP A DEGREE TO START UPWARD TREND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 125 PM EDT THU MAY 16 2013
MAIN FLUX OF MOISTURE AND LIFT TO REMAIN REMOVED TO THE SOUTH OF
BOTH TAF SITES THROUGH THE PERIOD. THIS WILL ALLOW FOR VFR
CONDITIONS ACROSS THE ARE WITH OCCASIONAL MID/HIGH CLOUDS AND
WINDS 10 KNOTS OR LESS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...BENTLEY
SHORT TERM...FISHER
LONG TERM...JAL
AVIATION...FISHER
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
656 PM EDT THU MAY 16 2013
.SYNOPSIS...
ISSUED AT 1031 AM EDT THU MAY 16 2013
A FRONTAL BOUNDARY WHICH HAS BROUGHT SHOWERS AND THUNDERSTORMS TO
PORTIONS OF SOUTHERN INDIANA AND OHIO TODAY WILL BEGIN TO SHIFT
NORTH BY FRIDAY AFTERNOON WHICH WILL BRING A LOW CHANCE OF SHOWERS
AND THUNDERSTORMS TO AREAS SOUTH OF US 30. SHOWER AND THUNDERSTORM
CHANCES WILL PERSIST THROUGH THE WEEKEND AS THE FRONTAL BOUNDARY REMAINS
ACROSS THE AREA. ABOVE NORMAL TEMPERATURES ARE EXPECTED LATE THIS
WEEK INTO THIS WEEKEND. CHANCES FOR SHOWERS AND THUNDERSTORMS
INCREASE EARLY NEXT WEEK AS A STORM SYSTEM APPROACHES FROM THE
WEST.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
HIGH PRESSURE HAS KEPT BULK OF MSTR JUST FAR ENOUGH SOUTH OF THE
AREA TODAY TO ALLOW FOR GENERALLY DRY CONDITIONS AND TEMPS MOVING
WELL THROUGH THE 70S IN MOST SPOTS. A FEW LIGHT SHOWERS/SPRINKLES
WERE NOTED ALONG FIRST OF 2 SFC THETA E GRADIENTS ACROSS FAR
SOUTHERN COUNTIES. THIS AREA IS EXPECTED TO SHIFT SOUTH OVER THE
NEXT SEVERAL HOURS AND REMOVE ANY CHANCE FOR PRECIP FOR THE
REMAINDER OF THE NIGHT. SECONDARY GRADIENT WAS LOCATED FURTHER
SOUTH ACROSS SOUTHERN INDIANA WHERE CONVECTION HAS BEEN ONGOING
MUCH OF THE DAY. MODELS TEND TO SUGGEST THAT THIS SECONDARY AREA
OF MSTR/GREATER LIFT SUPPORT WITH MAIN SFC BOUNDARY WILL BRING
INCREASING CHANCES FOR SHOWERS AND STORMS ON FRIDAY. IT WOULD
APPEAR THAT MOST FAVORABLE TIMING WOULD BE MID TO LATE AFTERNOON
FRIDAY IN FAR SW SECTIONS WITH PROGRESSION NE HAMPERED SOMEWHAT BY
DRY AIR/SEMI DRY GROUND CONDITIONS. IF NEW RUN OF SPC 4KM WRF IS
FOLLOWED...CONVECTION WOULD NOT ARRIVE UNTIL AFTER 00Z SAT. HAVE
ADJUSTED GRIDS TO REFLECT THIS WITH SLGT CHC TO CHC POPS CONFINED
TO AFTERNOON.
CLOUD COVER WILL BE ON THE INCREASE...WHICH WILL BUT A DAMPER ON
POTENTIAL CLIMB IN HIGHS. THAT BEING SAID...HIGHS SHOULD STILL END
UP ABOVE NORMAL CLIMBING INTO THE MID AND UPPER 70S.
&&
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
WATER VAPOR IMAGERY AND LATEST RAP ANALYSIS THAT IS DEPICTING MID
LEVEL CIRCULATION MOVING EASTWARD ACROSS THE SOUTHERN PLAINS THIS
AFTERNOON WILL HAVE AN IMPACT ON THE BEGINNING OF THE EXTENDED
FCST PERIOD AS IT MOVES ACROSS THE TN VALLEY. THIS WILL ACT ON
STATIONARY SFC BOUNDARY IN ADVECTING MOISTURE IN AN OVERRUNNING
FASHION BACK NORTH OF THE BOUNDARY AND LEND SUPPORT TO WIDELY
SCATTERED CONVECTION OVER THE SW HALF OF THE CWA. FOCUS WILL THEN
SHIFT TO AMPLIFICATION OF THE UPPER LEVEL PATTERN AS STRONG JET
DYNAMICS CURRENTLY WELL OUT IN THE PACIFIC ARE PROGGED BY MEDIUM
RANGE MODELS TO COME ONSHORE AND DEVELOP DEEP UPPER TROF OVER THE
WESTERN US. THIS WILL INDUCE DOWNSTREAM RIDGING THAT WILL BUILD
INTO THE REGION SUN/MON BRINGING WARMER AND MAINLY DRY CONDITIONS
TO THE AREA. WESTERN CONUS UPPER TROF THEN EXPECTED TO BECOME
VERTICALLY STACKED CLOSED SYSTEM IN THE NORTHERN PLAINS WHICH
MODELS ARE STRUGGLING WITH TIMING OF THE EVENTUAL EJECTION OF THIS
SYSTEM INTO OUR AREA. AS EXPECTED OVERALL TREND CONTINUES TO BE
SLOWER WITH ARRIVAL OF MAIN SYSTEM NOW DELAYED TO TUE/WED
TIMEFRAME AND BRINGING WITH IT THE BEST CHANCES FOR PRECIP. PRIOR
TO ITS ARRIVAL...BECOMING MORE AND MORE DIFFICULT TO PICK OUT
MODELS HANDLING OF INCREASINGLY DIFFUSE SFC BOUNDARY BUT
INDICATIONS ARE BOUNDARY WILL LIFT NORTH OF THE AREA IN
CONJUNCTION WITH UPPER RIDGE MOVING OVER THE AREA WHICH SHOULD
LEAVE MUCH OF THE FORECAST AREA IN A CAPPED WARM SECTOR SUN/MON.
LOW CONFIDENCE IN ANY ONE PARTICULAR SCENARIO WITH THIS SETUP BUT
WILL STILL INJECT A PERIOD OR TWO OF DRY WEATHER TO REFLECT THIS.
ANTICIPATE TEMPS WELL INTO THE 80S ON MONDAY DEPENDING ON AMOUNT
OF SUN...BUMPED ALLBLEND UP A DEGREE TO START UPWARD TREND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 125 PM EDT THU MAY 16 2013
MAIN FLUX OF MOISTURE AND LIFT TO REMAIN REMOVED TO THE SOUTH OF
BOTH TAF SITES THROUGH THE PERIOD. THIS WILL ALLOW FOR VFR
CONDITIONS ACROSS THE ARE WITH OCCASIONAL MID/HIGH CLOUDS AND
WINDS 10 KNOTS OR LESS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...STEINWEDEL/KG
SHORT TERM...FISHER
LONG TERM...JAL
AVIATION...FISHER
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
230 PM EDT THU MAY 16 2013
.SYNOPSIS...
ISSUED AT 1031 AM EDT THU MAY 16 2013
A FEW LIGHT SHOWERS OR ISOLATED THUNDERSTORMS COULD SKIM THE FAR
SOUTHWEST PORTION OF THE AREA THIS AFTERNOON. OTHERWISE, MOSTLY
DRY CONDITIONS ARE EXPECTED TODAY INTO FRIDAY MORNING, AS HIGH
PRESSURE BUILDS INTO THE GREAT LAKES FORCING A FRONTAL BOUNDARY
SOUTH INTO CENTRAL INDIANA. THIS FRONT IS EXPECTED TO BUCKLE BACK
NORTH LATER FRIDAY INTO THE WEEKEND WITH A LOW CHANCE FOR SHOWERS
AND THUNDERSTORMS MAINLY SOUTH OF ROUTE 30 IN INDIANA AND MICHIGAN
EACH DAY. ABOVE NORMAL TEMPERATURES ARE EXPECTED LATE THIS WEEK
INTO THIS WEEKEND. CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE
EARLY NEXT WEEK AS A STORM SYSTEM APPROACHES FROM THE WEST.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
HIGH PRESSURE HAS KEPT BULK OF MSTR JUST FAR ENOUGH SOUTH OF THE
AREA TODAY TO ALLOW FOR GENERALLY DRY CONDITIONS AND TEMPS MOVING
WELL THROUGH THE 70S IN MOST SPOTS. A FEW LIGHT SHOWERS/SPRINKLES
WERE NOTED ALONG FIRST OF 2 SFC THETA E GRADIENTS ACROSS FAR
SOUTHERN COUNTIES. THIS AREA IS EXPECTED TO SHIFT SOUTH OVER THE
NEXT SEVERAL HOURS AND REMOVE ANY CHANCE FOR PRECIP FOR THE
REMAINDER OF THE NIGHT. SECONDARY GRADIENT WAS LOCATED FURTHER
SOUTH ACROSS SOUTHERN INDIANA WHERE CONVECTION HAS BEEN ONGOING
MUCH OF THE DAY. MODELS TEND TO SUGGEST THAT THIS SECONDARY AREA
OF MSTR/GREATER LIFT SUPPORT WITH MAIN SFC BOUNDARY WILL BRING
INCREASING CHANCES FOR SHOWERS AND STORMS ON FRIDAY. IT WOULD
APPEAR THAT MOST FAVORABLE TIMING WOULD BE MID TO LATE AFTERNOON
FRIDAY IN FAR SW SECTIONS WITH PROGRESSION NE HAMPERED SOMEWHAT BY
DRY AIR/SEMI DRY GROUND CONDITIONS. IF NEW RUN OF SPC 4KM WRF IS
FOLLOWED...CONVECTION WOULD NOT ARRIVE UNTIL AFTER 00Z SAT. HAVE
ADJUSTED GRIDS TO REFLECT THIS WITH SLGT CHC TO CHC POPS CONFINED
TO AFTERNOON.
CLOUD COVER WILL BE ON THE INCREASE...WHICH WILL BUT A DAMPER ON
POTENTIAL CLIMB IN HIGHS. THAT BEING SAID...HIGHS SHOULD STILL END
UP ABOVE NORMAL CLIMBING INTO THE MID AND UPPER 70S.
&&
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
WATER VAPOR IMAGERY AND LATEST RAP ANALYSIS THAT IS DEPICTING MID
LEVEL CIRCULATION MOVING EASTWARD ACROSS THE SOUTHERN PLAINS THIS
AFTERNOON WILL HAVE AN IMPACT ON THE BEGINNING OF THE EXTENDED
FCST PERIOD AS IT MOVES ACROSS THE TN VALLEY. THIS WILL ACT ON
STATIONARY SFC BOUNDARY IN ADVECTING MOISTURE IN AN OVERRUNNING
FASHION BACK NORTH OF THE BOUNDARY AND LEND SUPPORT TO WIDELY
SCATTERED CONVECTION OVER THE SW HALF OF THE CWA. FOCUS WILL THEN
SHIFT TO AMPLIFICATION OF THE UPPER LEVEL PATTERN AS STRONG JET
DYNAMICS CURRENTLY WELL OUT IN THE PACIFIC ARE PROGGED BY MEDIUM
RANGE MODELS TO COME ONSHORE AND DEVELOP DEEP UPPER TROF OVER THE
WESTERN US. THIS WILL INDUCE DOWNSTREAM RIDGING THAT WILL BUILD
INTO THE REGION SUN/MON BRINGING WARMER AND MAINLY DRY CONDITIONS
TO THE AREA. WESTERN CONUS UPPER TROF THEN EXPECTED TO BECOME
VERTICALLY STACKED CLOSED SYSTEM IN THE NORTHERN PLAINS WHICH
MODELS ARE STRUGGLING WITH TIMING OF THE EVENTUAL EJECTION OF THIS
SYSTEM INTO OUR AREA. AS EXPECTED OVERALL TREND CONTINUES TO BE
SLOWER WITH ARRIVAL OF MAIN SYSTEM NOW DELAYED TO TUE/WED
TIMEFRAME AND BRINGING WITH IT THE BEST CHANCES FOR PRECIP. PRIOR
TO ITS ARRIVAL...BECOMING MORE AND MORE DIFFICULT TO PICK OUT
MODELS HANDLING OF INCREASINGLY DIFFUSE SFC BOUNDARY BUT
INDICATIONS ARE BOUNDARY WILL LIFT NORTH OF THE AREA IN
CONJUNCTION WITH UPPER RIDGE MOVING OVER THE AREA WHICH SHOULD
LEAVE MUCH OF THE FORECAST AREA IN A CAPPED WARM SECTOR SUN/MON.
LOW CONFIDENCE IN ANY ONE PARTICULAR SCENARIO WITH THIS SETUP BUT
WILL STILL INJECT A PERIOD OR TWO OF DRY WEATHER TO REFLECT THIS.
ANTICIPATE TEMPS WELL INTO THE 80S ON MONDAY DEPENDING ON AMOUNT
OF SUN...BUMPED ALLBLEND UP A DEGREE TO START UPWARD TREND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 125 PM EDT THU MAY 16 2013
MAIN FLUX OF MOISTURE AND LIFT TO REMAIN REMOVED TO THE SOUTH OF
BOTH TAF SITES THROUGH THE PERIOD. THIS WILL ALLOW FOR VFR
CONDITIONS ACROSS THE ARE WITH OCCASIONAL MID/HIGH CLOUDS AND
WINDS 10 KNOTS OR LESS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...STEINWEDEL/KG
SHORT TERM...FISHER
LONG TERM...JAL
AVIATION...FISHER
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS TOPEKA KS
725 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 725 PM CDT FRI MAY 17 2013
WITH THE LATEST RAP AND NAM MODELS SHOWING THE STRATUS REMAINING
MAINLY TO THE SOUTHWEST OF THE FORECAST AREA LATE TONIGHT...AM A
LITTLE CONCERNED FOR SOME GROUND FOG FORMATION BETWEEN 08 AND 10Z
THINKING WINDS WILL BE LESS THAN 5 KTS AND SKIES MOSTLY CLEAR.
DEWPOINT TEMPS ACROSS SOUTHERN MO IN THE LOWER 60S AND A
PERSISTENT SOUTHEAST WIND SUGGEST DEWPOINTS ARE MOT LIKELY TO DROP
OFF MUCH TONIGHT. BECAUSE OF THIS HAVE INSERTED A MENTION OF
PATCHY FOG FOR LATE TONIGHT AND EARLY SATURDAY MORNING.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 342 PM CDT FRI MAY 17 2013
SCATTERED TO BROKEN STRATOCU DECK ACROSS THE EASTERN 2/3 OF THE
COUNTY WARNING AREA WILL GRADUALLY DECREASE AFT PEAK
HEATING...BEFORE REDEVELOPING/THICKENING AGAIN LATER TONIGHT AS
MOIST AXIS LIFTS NORTHWARD TOWARDS THE CWA. WILL KEEP THE FCST DRY
THROUGH TONIGHT...BUT INCREASE CLOUDS LATER AGAIN SOUTHWEST TO
NORTHEAST. ALTHOUGH NOT AS DENSE AS LAST NIGHT...STILL THINK SOME
FOG MAY FORM WITH THE STRATUS LATE...BUT NOT DENSE ENOUGH TO INSERT
INTO GRIDS AT THIS POINT. LOWS SHOULD BE IN THE LOW TO MIDDLE 60S.
EXPECT THIS STRATUS DECK SHOULD THIN AGAIN BY MIDDAY/AFTERNOON
SATURDAY ALLOWING FOR HIGH TEMPS TO WARM INTO THE MIDDLE 80S. MODELS
DIFFER ON WHETHER CAPPING INVERSION BY MIDDAY/AFTERNOON CAN BE
OVERCOME ENOUGH FOR SOME SCT CONVECTION TO DEVELOP AS A WEAK WAVE
APPROACHES FROM THE SOUTHWEST. HOWEVER...WITH A STRENGTHENING
ELEVATED MIXED LAYER WITH LITTLE IN THE WAY OF FORCING IN THAT
LAYER...FEEL THE MODELS MAY BE UNDER DOING CINH AND HAVE DECIDED TO
CONTINUE WITH A DRY FCST...OR MORE IN LINE WITH THE EC MODEL.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 342 PM CDT FRI MAY 17 2013
MODELS CONTINUE TO SIGNAL FOR SOME CONVECTION TO DEVELOP ABOVE THE
CAPPING INVERSION SATURDAY NIGHT AS THE LOW LEVEL JET INCREASES AS
WELL AS ISENTROPIC LIFT. WITH NOT HIGH CONFIDENCE WILL CONTINUE TO
KEEP POPS AROUND 20 PERCENT.
BY 12Z SUNDAY THE UPPER TROUGH AXIS WILL MOVE TO NEAR THE WESTERN
KANSAS BORDER. THE SURFACE LOW WILL CONTINUE TO DEEPEN IN WESTERN
KANSAS. SOME ELEVATED STORMS ARE POSSIBLE SUNDAY MORNING FROM ANY
OVERNIGHT DEVELOPMENT. THE UPPER TROUGH WILL MOVE OUT INTO THE
PLAINS SUNDAY TAKING ON A NEGATIVE TILT. THE TROUGH AXIS LOOKS TO
PASS TO THE EAST OF THE CWA SUNDAY NIGHT. ZERO TO 6 KM SHEAR OF 30
TO 40 KTS...1500-2500 J/KG OF ML CAPE ALONG WITH ABUNDANT MOISTURE
IN THE WARM SECTOR. LAPSE RATES STEEPEN AS THE UPPER TROUGH PIVOTS
NORTHEAST AND ERODES THE CAPPING INVERSION. WILL CONTINUE WITH
LIKELY CHANCES OF THUNDERSTORMS IN THE EASTERN 2/3RDS OF THE CWA ON
SUNDAY AFTERNOON WITH THE HIGHER POPS OVER EAST CENTRAL KANSAS
SUNDAY EVENING. GIVEN SHEAR AND INSTABILITY WITH ABUNDANT MOISTURE
STRONG TO SEVERE STORMS ARE POSSIBLE WITH LARGE HAIL AND DAMAGING
WINDS THE MAIN THREAT. THE TORNADO THREAT REMAINS SUNDAY AND SUNDAY
EVENING...ALTHOUGH NOT MUCH CURVATURE TO THE HODOGRAPHS AND TURNING
IN THE FORECAST HODOGRAPHS CANNOT RULE OUT ANY WITH SUPERCELLS.
MONDAY IS STILL A LITTLE BIT OF A QUESTION MARK AS TO HOW FAR
SOUTHEAST THE BOUNDARY WILL SET UP ACROSS EAST CENTRAL KANSAS SO
WILL CONTINUE TO KEEP THE HIGHER THUNDERSTORM CHANCES IN THE
SOUTHEAST CWA. STRONG TO SEVERE STORMS WILL AGAIN BE POSSIBLE MONDAY
AFTERNOON AND EVENING. THE UPPER LOW CONTINUE TO SPIN OVER THE
CENTRAL PLAINS THROUGH WEDNESDAY. THIS WILL KEEP SMALL CHANCES OF
SHOWERS AND THUNDERSTORMS TUESDAY THROUGH EARLY THURSDAY. A RIDGE
BUILDS OVER THE PLAINS LATE THURSDAY AND FRIDAY BRINGING AN END TO
THE PRECIPITATION CHANCES. FROM MONDAY THROUGH FRIDAY TEMPERATURES
WILL BE IN THE 70S FOR HIGHS AND 50S FOR LOWS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 623 PM CDT FRI MAY 17 2013
MODELS SHOW THE BOUNDARY LAYER REMAINING CAPPED WITH RAISING MID
LEVEL HEIGHTS OVERNIGHT. SO THERE SHOULD BE NO CHANCE FOR PRECIP.
THINK FOG FORMATION IS PROBABLE DURING THE PREDAWN HOURS.
CLEARING SKIES AND LIGHT WINDS SHOULD ALLOW THE BOUNDARY LAYER TO
COOL NEAR THE DEWPOINT TEMP BEFORE THE STRATUS HAS A CHANCE TO
MOVE INTO THE TERMINALS. AND WITH DEWPOINTS UPSTREAM IN THE LOWER
60S...DO NOT EXPECT MUCH DRYING IN THE BOUNDARY LAYER. THEREFORE
HAVE INCLUDED SOME IFR VSBY RESTRICTIONS BETWEEN 10Z AND 14Z. THE
BOUNDARY LAYER IS EXPECTED TO BECOME MORE MIXED BY 14Z ALLOWING
CONDITIONS TO GRADUALLY IMPROVE THROUGH THE AFTERNOON SATURDAY.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WOLTERS
SHORT TERM...63
LONG TERM...53
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS JACKSON KY
125 PM EDT THU MAY 16 2013
.UPDATE...
ISSUED AT 1244 PM EDT THU MAY 16 2013
ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS THE NORTHERN
PART OF THE FORECAST AREA. CURRENT TRENDS AND NEAR TERM GUIDANCE
SUPPORTS IDEA OF KEEPING THE GREATEST SHOWER AND THUNDERSTORM
COVERAGE IN THE NORTH...WITH INCREASING COVERAGE THROUGH MID
AFTERNOON. CONVECTION WILL BE SLOWER TO DEVELOP IN THE SOUTH...AND
HAVE INCREASED MAXIMUM TEMPERATURES WHERE PRECIPITATION WILL HOLD OFF
FOR MOST IF NOT ALL OF THE DAY. NDFD AND ZFP HAVE BEEN UPDATED.
UPDATE ISSUED AT 1046 AM EDT THU MAY 16 2013
CONVECTION ASSOCIATED WITH THE SURFACE FRONT OVER OH HAS MADE LITTLE
SOUTHWARD PROGRESS THIS MORNING. HOWEVER...A BOUNDARY FROM SOUTHERN
OH CONVECTION HAS MOVED SOUTH INTO KY...AND THIS IS INTERACTING WITH
ENERGY ROTATING NORTHEAST FROM THE MID LEVEL LOW OVER OK. SHOWERS AND
THUNDERSTORMS HAVE BEEN DEVELOPING FROM SDF EAST TO SOUTH OF LEX.
THE 12Z HRRR IS HANDLING THIS FAIRLY WELL...AND THE 12Z NAM IS ALSO
SHOWING THIS. BASED ON CURRENT ANALYSIS...TRENDS AND LATEST MODEL
GUIDANCE HAVE MADE ADJUSTMENTS TO PRECIPITATION CHANCES FOR TODAY. HAVE
INCREASED COVERAGE IN THE CENTRAL PART OF THE AREA TO SCATTERED WITH
A 30 PERCENT CHANCE AND HAVE DECREASED THE PROBABILITY IN THE FAR
SOUTH FROM 40 PERCENT TO 30 PERCENT. WILL CONTINUE TO CARRY THE
HIGHEST SHOWER AND THUNDERSTORM CHANCES IN THE NORTH.
UPDATE ISSUED AT 857 AM EDT THU MAY 16 2013
CLOUDS HAVE INCREASED QUICKLY THIS MORNING...AND HAVE UPDATED THE
NDFD AND ZFP TO REFLECT THIS. MOSTLY CLOUDY SKIES NOW FORECAST ACROSS
THE ENTIRE AREA FOR TODAY. HRRR IS HANDLING CURRENT CONVECTION FAIRLY
WELL. 11Z HRRR POINTS TOWARDS A NORTH TO SOUTH RAIN PROBABILITY
CHANCE THIS AFTERNOON...WITH BEST CHANCE IN THE NORTH. WILL TAKE A
LOOK AT INCOMING 12Z DATA FOR ANY POSSIBLE UPDATES TO THE RAIN
PROBABILITIES FOR THIS AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
THERE ARE TWO MAIN INGREDIENTS TO THIS FORECAST WHICH INDIVIDUALLY
AND COLLECTIVELY ADD SOME DIFFICULTY TO THE FORECAST. THERE IS A COLD
FRONT SOUTH OF THE GREAT LAKES WHICH IS SAGGING TO THE SOUTH. THERE
IS ALSO AN UPPER LOW OVER OKLAHOMA EMBEDDED IS A WEAKER SOUTHERLY
STREAM. THESE TWO SYSTEMS ARE BOTH GOING TO BE EFFECTING THE WEATHER
OVER THE AREA OVER THE NEXT TWO DAYS. AT 230 AM THERE WAS A LINE OF
SHOWER AND THUNDERSTORMS WHICH EXTENDED FROM SOUTHWEST PENNSYLVANIA AND
THEN PASSED SOUTH OF COLUMBUS AND THEN ACROSS DAYTON. THIS SYSTEM
WILL BE SAGGING TO THE SOUTH. THE BIG QUESTION IS HOW FAR SOUTH WILL
THE FRONT MOVE. THE NAM STALLS THIS FRONT OUT ALONG THE OHIO RIVER
VALLEY. AS A RESULT...KEPT THE BEST CHANCE FOR RAIN TODAY AND
TONIGHT NORTH OF I 64 IN THE BLUEGRASS. THE MODELS ARE ALSO
GENERATING SOME ENERGY OUT AHEAD OF THE UPPER LOW WHICH WILL BE
MOVING TO THE EAST THE AREA SOUTH OF I 64 WILL BE IN THE GENERALLY
UNSTABLE WARM SECTOR TODAY AND TONIGHT WITH SOME ENERGY SPINNING
AROUND THE UPPER LOW WHICH MAY MOVE INTO THE AREA LATER TODAY. THIS
IS MOST LIKELY GOING TO EFFECT THE AREA SOUTH OF THE HAL ROGERS
PARKWAY. SO THERE IS A SLOT ACROSS THE CENTRAL PORTION OF EASTERN
KENTUCKY WHICH SHOULD BE SOUTH OF THE INFLUENCE OF THE FRONT AND
NORTH OF THE INFLUENCE OF THE UPPER LOW. THE ONE THING THAT IS A BIT
OF A WILD CARD IS IF THE THUNDERSTORMS TO THE NORTH ARE ABLE TO
CREATE A COLD POOL TODAY WHICH PROPAGATES SOUTH ACROSS EASTERN
KENTUCKY. THE NAM BUFFER SOUNDING HAS A LIFTED INDEX OF AROUND -5
THIS AFTERNOON...SO IF A COLD POOL DOES MOVE INTO THE AREA...THERE
WILL BE PLENTY OF INSTABILITY TO KEEP IT GOING. THE SCENARIO IS NOT
IN THE FORECAST...HOWEVER BEARS WATCHING.THERE SHOULD BE PLENTY OF
CLOUDS TODAY...HOWEVER THE LOWER LAYERS ARE FAIRLY DRY AND IT SHOULD
TAKE A WHILE TO BE ABLE TO MOISTEN THEM UP ENOUGH FOR THE RAIN TO
REACH THE GROUND. THE TEMPERATURES WILL BE SO DEPENDENT ON HOW
EXTENSIVE THE SHOWERS WILL BE TODAY. WENT A BIT WARMER THAN THE MODEL
CONSENSUS AND BLENDED CLOSER TO THE WARMER NAM MOS FOR TODAY AND
TOMORROW.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
MODE LS ARE IN FAIR AGREEMENT...BETTER WITH RELATIVELY SLOW BUT
PROGRESSIVE UPPER AIR PATTERN THAN WITH SURFACE FEATURES. EXTENDED
STARTS OUT WITH AN OPEN WAVE TRACKING EASTWARD ACROSS THE OHIO/TN
VALLEY REGIONS THROUGH THE WEEKEND. SHORTWAVE RIDGE THEN TRANSITS
THE REGION MONDAY BEFORE SLOW MOVING LOW PRESSURE SYSTEM OVER THE
NORTH CENTRAL PLAINS SHIFTS INTO THE MIDWEST...OR GREAT LAKES BY THE
END OF THE FORECAST WINDOW. WE FALL UNDER A SOUTHWEST FLOW REGIME
ALOFT DURING THE INTERIM. ECMWF...WITH SUPPORT FROM THE CANADIAN
APPEARS MORE ORGANIZED AND FURTHER SOUTH WITH THE UPPER LOW MOVING
OUT OF THE PLAINS AND INTO THE MIDWEST VERSUS THE GFS WHICH KEEPS
THE UPPER LOW UP OVER THE NORTHERN TIER. MODELS DIVERGE EVEN MORE
SIGNIFICANTLY JUST BEYOND THE END OF THE FORECAST PERIOD. TENDENCY
IS TO LEAN TOWARDS THE TYPICALLY MORE ACCURATE...RELIABLE ECMWF WITH
RESPECT TO THE EVOLUTION OF THE UPPER AIR PATTERN.
AT THE SURFACE...AGAIN MODELS DIFFER CONSIDERABLY ON THE EVENTUAL
POSITION SOUTHERN EXTENT OF SURFACE COLD FRONTAL BOUNDARY ACROSS THE
OHIO VALLEY EARLY IN THE FORECAST. THE NAM/GFS BRINGS THE BOUNDARY
AS FAR SOUTH AS AN IND TO DAY LINE LATE THIS AFTERNOON AND/OR EARLY
FRIDAY MORNING RESPECTIVELY. THE ECMWF BRINGS THE BOUNDARY SOUTHWARD
TO BETWEEN DAY AND CVG BY EARLY SATURDAY MORNING...APPARENTLY WITH
SUPPORT FROM THE UPPER LEVEL WAVE THAT PUSHES THROUGH THE REGION.
END RESULT IS THAT THE BOUNDARY NEVER REALLY SEEMS TO MAKE IT AS FAR
SOUTH AS THE OHIO RIVER...IN A TRUE SUMMERTIME LIKE FASHION. THIS
DOES NOT BODE WELL FOR THE OPPORTUNITY OF RAIN UNLESS CONVECTION
ALONG THE FRONTAL BOUNDARY BECOMES MORE ORGANIZED AND MANAGES TO
MAKE A SURGE SOUTHWARD INTO OUR AREA. BEST OPPORTUNITY FOR THIS...
OR JUST SHOWER AND THUNDERSTORM ACTIVITY IN GENERAL WILL COME AS THE
UPPER LEVEL WAVE OR DISTURBANCE GRADUALLY SHIFTS THROUGH THE REGION
SATURDAY AND SUNDAY. TRENDED DRIER SUNDAY NIGHT THROUGH MONDAY NIGHT
WITH UPPER LEVEL RIDGING BUILDING INTO THE AREA. THREAT OF SHOWERS
AND THUNDERSTORMS INCREASE AGAIN TOWARDS THE END OF THE FORECAST
WINDOW...TUESDAY NIGHT AND/OR WEDNESDAY AND BEYOND AS SYSTEM MORE
THAN LIKELY MAKES A MOVE TOWARDS OUR AREA OUT OF THE NORTH CENTRAL
PLAINS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 125 PM EDT THU MAY 16 2013
A STATIONARY FRONT OVER SOUTHERN OHIO WILL KEEP THE THREAT OF SHOWERS
AND THUNDERSTORMS GREATEST IN THE NORTHERN PART OF THE FORECAST
AREA...NORTH OF THE TAF SITES...THROUGH THE AFTERNOON. NUMEROUS
SHOWERS AND THUNDERSTORMS WILL AFFECT THE NORTHERN PART OF THE
FORECAST AREA...WITH LOCAL IFR CONDITIONS. FROM JKL...SOUTH TO THE TN
AND VA BORDER...THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON AND
EVENING...BUT COVERAGE WILL BE MUCH LESS. FOR THE SOUTHERN PART OF
THE FORECAST AREA...INCLUDING THE TAF SITES...VFR CONDITIONS ARE
EXPECTED THROUGH THE FORECAST PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...JJ
LONG TERM...RAY
AVIATION...SBH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1245 PM EDT THU MAY 16 2013
.UPDATE...
ISSUED AT 1244 PM EDT THU MAY 16 2013
ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS THE NORTHERN
PART OF THE FORECAST AREA. CURRENT TRENDS AND NEAR TERM GUIDANCE
SUPPORTS IDEA OF KEEPING THE GREATEST SHOWER AND THUNDERSTORM
COVERAGE IN THE NORTH...WITH INCREASING COVERAGE THROUGH MID
AFTERNOON. CONVECTION WILL BE SLOWER TO DEVELOP IN THE SOUTH...AND
HAVE INCREASED MAXIMUM TEMPERATURES WHERE PRECIPITATION WILL HOLD OFF
FOR MOST IF NOT ALL OF THE DAY. NDFD AND ZFP HAVE BEEN UPDATED.
UPDATE ISSUED AT 1046 AM EDT THU MAY 16 2013
CONVECTION ASSOCIATED WITH THE SURFACE FRONT OVER OH HAS MADE LITTLE
SOUTHWARD PROGRESS THIS MORNING. HOWEVER...A BOUNDARY FROM SOUTHERN
OH CONVECTION HAS MOVED SOUTH INTO KY...AND THIS IS INTERACTING WITH
ENERGY ROTATING NORTHEAST FROM THE MID LEVEL LOW OVER OK. SHOWERS AND
THUNDERSTORMS HAVE BEEN DEVELOPING FROM SDF EAST TO SOUTH OF LEX.
THE 12Z HRRR IS HANDLING THIS FAIRLY WELL...AND THE 12Z NAM IS ALSO
SHOWING THIS. BASED ON CURRENT ANALYSIS...TRENDS AND LATEST MODEL
GUIDANCE HAVE MADE ADJUSTMENTS TO PRECIPITATION CHANCES FOR TODAY. HAVE
INCREASED COVERAGE IN THE CENTRAL PART OF THE AREA TO SCATTERED WITH
A 30 PERCENT CHANCE AND HAVE DECREASED THE PROBABILITY IN THE FAR
SOUTH FROM 40 PERCENT TO 30 PERCENT. WILL CONTINUE TO CARRY THE
HIGHEST SHOWER AND THUNDERSTORM CHANCES IN THE NORTH.
UPDATE ISSUED AT 857 AM EDT THU MAY 16 2013
CLOUDS HAVE INCREASED QUICKLY THIS MORNING...AND HAVE UPDATED THE
NDFD AND ZFP TO REFLECT THIS. MOSTLY CLOUDY SKIES NOW FORECAST ACROSS
THE ENTIRE AREA FOR TODAY. HRRR IS HANDLING CURRENT CONVECTION FAIRLY
WELL. 11Z HRRR POINTS TOWARDS A NORTH TO SOUTH RAIN PROBABILITY
CHANCE THIS AFTERNOON...WITH BEST CHANCE IN THE NORTH. WILL TAKE A
LOOK AT INCOMING 12Z DATA FOR ANY POSSIBLE UPDATES TO THE RAIN
PROBABILITIES FOR THIS AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
THERE ARE TWO MAIN INGREDIENTS TO THIS FORECAST WHICH INDIVIDUALLY
AND COLLECTIVELY ADD SOME DIFFICULTY TO THE FORECAST. THERE IS A COLD
FRONT SOUTH OF THE GREAT LAKES WHICH IS SAGGING TO THE SOUTH. THERE
IS ALSO AN UPPER LOW OVER OKLAHOMA EMBEDDED IS A WEAKER SOUTHERLY
STREAM. THESE TWO SYSTEMS ARE BOTH GOING TO BE EFFECTING THE WEATHER
OVER THE AREA OVER THE NEXT TWO DAYS. AT 230 AM THERE WAS A LINE OF
SHOWER AND THUNDERSTORMS WHICH EXTENDED FROM SOUTHWEST PENNSYLVANIA AND
THEN PASSED SOUTH OF COLUMBUS AND THEN ACROSS DAYTON. THIS SYSTEM
WILL BE SAGGING TO THE SOUTH. THE BIG QUESTION IS HOW FAR SOUTH WILL
THE FRONT MOVE. THE NAM STALLS THIS FRONT OUT ALONG THE OHIO RIVER
VALLEY. AS A RESULT...KEPT THE BEST CHANCE FOR RAIN TODAY AND
TONIGHT NORTH OF I 64 IN THE BLUEGRASS. THE MODELS ARE ALSO
GENERATING SOME ENERGY OUT AHEAD OF THE UPPER LOW WHICH WILL BE
MOVING TO THE EAST THE AREA SOUTH OF I 64 WILL BE IN THE GENERALLY
UNSTABLE WARM SECTOR TODAY AND TONIGHT WITH SOME ENERGY SPINNING
AROUND THE UPPER LOW WHICH MAY MOVE INTO THE AREA LATER TODAY. THIS
IS MOST LIKELY GOING TO EFFECT THE AREA SOUTH OF THE HAL ROGERS
PARKWAY. SO THERE IS A SLOT ACROSS THE CENTRAL PORTION OF EASTERN
KENTUCKY WHICH SHOULD BE SOUTH OF THE INFLUENCE OF THE FRONT AND
NORTH OF THE INFLUENCE OF THE UPPER LOW. THE ONE THING THAT IS A BIT
OF A WILD CARD IS IF THE THUNDERSTORMS TO THE NORTH ARE ABLE TO
CREATE A COLD POOL TODAY WHICH PROPAGATES SOUTH ACROSS EASTERN
KENTUCKY. THE NAM BUFFER SOUNDING HAS A LIFTED INDEX OF AROUND -5
THIS AFTERNOON...SO IF A COLD POOL DOES MOVE INTO THE AREA...THERE
WILL BE PLENTY OF INSTABILITY TO KEEP IT GOING. THE SCENARIO IS NOT
IN THE FORECAST...HOWEVER BEARS WATCHING.THERE SHOULD BE PLENTY OF
CLOUDS TODAY...HOWEVER THE LOWER LAYERS ARE FAIRLY DRY AND IT SHOULD
TAKE A WHILE TO BE ABLE TO MOISTEN THEM UP ENOUGH FOR THE RAIN TO
REACH THE GROUND. THE TEMPERATURES WILL BE SO DEPENDENT ON HOW
EXTENSIVE THE SHOWERS WILL BE TODAY. WENT A BIT WARMER THAN THE MODEL
CONSENSUS AND BLENDED CLOSER TO THE WARMER NAM MOS FOR TODAY AND
TOMORROW.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
MODE LS ARE IN FAIR AGREEMENT...BETTER WITH RELATIVELY SLOW BUT
PROGRESSIVE UPPER AIR PATTERN THAN WITH SURFACE FEATURES. EXTENDED
STARTS OUT WITH AN OPEN WAVE TRACKING EASTWARD ACROSS THE OHIO/TN
VALLEY REGIONS THROUGH THE WEEKEND. SHORTWAVE RIDGE THEN TRANSITS
THE REGION MONDAY BEFORE SLOW MOVING LOW PRESSURE SYSTEM OVER THE
NORTH CENTRAL PLAINS SHIFTS INTO THE MIDWEST...OR GREAT LAKES BY THE
END OF THE FORECAST WINDOW. WE FALL UNDER A SOUTHWEST FLOW REGIME
ALOFT DURING THE INTERIM. ECMWF...WITH SUPPORT FROM THE CANADIAN
APPEARS MORE ORGANIZED AND FURTHER SOUTH WITH THE UPPER LOW MOVING
OUT OF THE PLAINS AND INTO THE MIDWEST VERSUS THE GFS WHICH KEEPS
THE UPPER LOW UP OVER THE NORTHERN TIER. MODELS DIVERGE EVEN MORE
SIGNIFICANTLY JUST BEYOND THE END OF THE FORECAST PERIOD. TENDENCY
IS TO LEAN TOWARDS THE TYPICALLY MORE ACCURATE...RELIABLE ECMWF WITH
RESPECT TO THE EVOLUTION OF THE UPPER AIR PATTERN.
AT THE SURFACE...AGAIN MODELS DIFFER CONSIDERABLY ON THE EVENTUAL
POSITION SOUTHERN EXTENT OF SURFACE COLD FRONTAL BOUNDARY ACROSS THE
OHIO VALLEY EARLY IN THE FORECAST. THE NAM/GFS BRINGS THE BOUNDARY
AS FAR SOUTH AS AN IND TO DAY LINE LATE THIS AFTERNOON AND/OR EARLY
FRIDAY MORNING RESPECTIVELY. THE ECMWF BRINGS THE BOUNDARY SOUTHWARD
TO BETWEEN DAY AND CVG BY EARLY SATURDAY MORNING...APPARENTLY WITH
SUPPORT FROM THE UPPER LEVEL WAVE THAT PUSHES THROUGH THE REGION.
END RESULT IS THAT THE BOUNDARY NEVER REALLY SEEMS TO MAKE IT AS FAR
SOUTH AS THE OHIO RIVER...IN A TRUE SUMMERTIME LIKE FASHION. THIS
DOES NOT BODE WELL FOR THE OPPORTUNITY OF RAIN UNLESS CONVECTION
ALONG THE FRONTAL BOUNDARY BECOMES MORE ORGANIZED AND MANAGES TO
MAKE A SURGE SOUTHWARD INTO OUR AREA. BEST OPPORTUNITY FOR THIS...
OR JUST SHOWER AND THUNDERSTORM ACTIVITY IN GENERAL WILL COME AS THE
UPPER LEVEL WAVE OR DISTURBANCE GRADUALLY SHIFTS THROUGH THE REGION
SATURDAY AND SUNDAY. TRENDED DRIER SUNDAY NIGHT THROUGH MONDAY NIGHT
WITH UPPER LEVEL RIDGING BUILDING INTO THE AREA. THREAT OF SHOWERS
AND THUNDERSTORMS INCREASE AGAIN TOWARDS THE END OF THE FORECAST
WINDOW...TUESDAY NIGHT AND/OR WEDNESDAY AND BEYOND AS SYSTEM MORE
THAN LIKELY MAKES A MOVE TOWARDS OUR AREA OUT OF THE NORTH CENTRAL
PLAINS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 725 AM EDT THU MAY 16 2013
VFR CONDITIONS WILL HOLD THROUGH THE TAF FORECAST PERIOD. A THREAT
OF THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON WITH THUNDERSTORMS
MOVING FROM THE NORTH IN THE JKL AREA AND FROM THE SOUTH FOR LOZ AND
SME. THERE IS ONLY AND SLIGHT CHANCE AT JKL AND A CHANCE AT SME AND
LOZ. THERE IS TOO MUCH UNCERTAINTY TO GO WITH A PREVAILING
THUNDERSTORM GROUP AS THE THUNDERSTORMS COULD STAY NORTH OR SOUTH AND
MAY NOT IMPACT THE TAF SITES.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...JJ
LONG TERM...RAY
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
1046 AM EDT THU MAY 16 2013
.UPDATE...
ISSUED AT 1046 AM EDT THU MAY 16 2013
CONVECTION ASSOCIATED WITH THE SURFACE FRONT OVER OH HAS MADE LITTLE
SOUTHWARD PROGRESS THIS MORNING. HOWEVER...A BOUNDARY FROM SOUTHERN
OH CONVECTION HAS MOVED SOUTH INTO KY...AND THIS IS INTERACTING WITH
ENERGY ROTATING NORTHEAST FROM THE MID LEVEL LOW OVER OK. SHOWERS AND
THUNDERSTORMS HAVE BEEN DEVELOPING FROM SDF EAST TO SOUTH OF LEX.
THE 12Z HRRR IS HANDLING THIS FAIRLY WELL...AND THE 12Z NAM IS ALSO
SHOWING THIS. BASED ON CURRENT ANALYSIS...TRENDS AND LATEST MODEL
GUIDANCE HAVE MADE ADJUSTMENTS TO PRECIPITATION CHANCES FOR TODAY. HAVE
INCREASED COVERAGE IN THE CENTRAL PART OF THE AREA TO SCATTERED WITH
A 30 PERCENT CHANCE AND HAVE DECREASED THE PROBABILITY IN THE FAR
SOUTH FROM 40 PERCENT TO 30 PERCENT. WILL CONTINUE TO CARRY THE
HIGHEST SHOWER AND THUNDERSTORM CHANCES IN THE NORTH.
UPDATE ISSUED AT 857 AM EDT THU MAY 16 2013
CLOUDS HAVE INCREASED QUICKLY THIS MORNING...AND HAVE UPDATED THE
NDFD AND ZFP TO REFLECT THIS. MOSTLY CLOUDY SKIES NOW FORECAST ACROSS
THE ENTIRE AREA FOR TODAY. HRRR IS HANDLING CURRENT CONVECTION FAIRLY
WELL. 11Z HRRR POINTS TOWARDS A NORTH TO SOUTH RAIN PROBABILITY
CHANCE THIS AFTERNOON...WITH BEST CHANCE IN THE NORTH. WILL TAKE A
LOOK AT INCOMING 12Z DATA FOR ANY POSSIBLE UPDATES TO THE RAIN
PROBABILITIES FOR THIS AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
THERE ARE TWO MAIN INGREDIENTS TO THIS FORECAST WHICH INDIVIDUALLY
AND COLLECTIVELY ADD SOME DIFFICULTY TO THE FORECAST. THERE IS A COLD
FRONT SOUTH OF THE GREAT LAKES WHICH IS SAGGING TO THE SOUTH. THERE
IS ALSO AN UPPER LOW OVER OKLAHOMA EMBEDDED IS A WEAKER SOUTHERLY
STREAM. THESE TWO SYSTEMS ARE BOTH GOING TO BE EFFECTING THE WEATHER
OVER THE AREA OVER THE NEXT TWO DAYS. AT 230 AM THERE WAS A LINE OF
SHOWER AND THUNDERSTORMS WHICH EXTENDED FROM SOUTHWEST PENNSYLVANIA AND
THEN PASSED SOUTH OF COLUMBUS AND THEN ACROSS DAYTON. THIS SYSTEM
WILL BE SAGGING TO THE SOUTH. THE BIG QUESTION IS HOW FAR SOUTH WILL
THE FRONT MOVE. THE NAM STALLS THIS FRONT OUT ALONG THE OHIO RIVER
VALLEY. AS A RESULT...KEPT THE BEST CHANCE FOR RAIN TODAY AND
TONIGHT NORTH OF I 64 IN THE BLUEGRASS. THE MODELS ARE ALSO
GENERATING SOME ENERGY OUT AHEAD OF THE UPPER LOW WHICH WILL BE
MOVING TO THE EAST THE AREA SOUTH OF I 64 WILL BE IN THE GENERALLY
UNSTABLE WARM SECTOR TODAY AND TONIGHT WITH SOME ENERGY SPINNING
AROUND THE UPPER LOW WHICH MAY MOVE INTO THE AREA LATER TODAY. THIS
IS MOST LIKELY GOING TO EFFECT THE AREA SOUTH OF THE HAL ROGERS
PARKWAY. SO THERE IS A SLOT ACROSS THE CENTRAL PORTION OF EASTERN
KENTUCKY WHICH SHOULD BE SOUTH OF THE INFLUENCE OF THE FRONT AND
NORTH OF THE INFLUENCE OF THE UPPER LOW. THE ONE THING THAT IS A BIT
OF A WILD CARD IS IF THE THUNDERSTORMS TO THE NORTH ARE ABLE TO
CREATE A COLD POOL TODAY WHICH PROPAGATES SOUTH ACROSS EASTERN
KENTUCKY. THE NAM BUFFER SOUNDING HAS A LIFTED INDEX OF AROUND -5
THIS AFTERNOON...SO IF A COLD POOL DOES MOVE INTO THE AREA...THERE
WILL BE PLENTY OF INSTABILITY TO KEEP IT GOING. THE SCENARIO IS NOT
IN THE FORECAST...HOWEVER BEARS WATCHING.THERE SHOULD BE PLENTY OF
CLOUDS TODAY...HOWEVER THE LOWER LAYERS ARE FAIRLY DRY AND IT SHOULD
TAKE A WHILE TO BE ABLE TO MOISTEN THEM UP ENOUGH FOR THE RAIN TO
REACH THE GROUND. THE TEMPERATURES WILL BE SO DEPENDENT ON HOW
EXTENSIVE THE SHOWERS WILL BE TODAY. WENT A BIT WARMER THAN THE MODEL
CONSENSUS AND BLENDED CLOSER TO THE WARMER NAM MOS FOR TODAY AND
TOMORROW.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
MODE LS ARE IN FAIR AGREEMENT...BETTER WITH RELATIVELY SLOW BUT
PROGRESSIVE UPPER AIR PATTERN THAN WITH SURFACE FEATURES. EXTENDED
STARTS OUT WITH AN OPEN WAVE TRACKING EASTWARD ACROSS THE OHIO/TN
VALLEY REGIONS THROUGH THE WEEKEND. SHORTWAVE RIDGE THEN TRANSITS
THE REGION MONDAY BEFORE SLOW MOVING LOW PRESSURE SYSTEM OVER THE
NORTH CENTRAL PLAINS SHIFTS INTO THE MIDWEST...OR GREAT LAKES BY THE
END OF THE FORECAST WINDOW. WE FALL UNDER A SOUTHWEST FLOW REGIME
ALOFT DURING THE INTERIM. ECMWF...WITH SUPPORT FROM THE CANADIAN
APPEARS MORE ORGANIZED AND FURTHER SOUTH WITH THE UPPER LOW MOVING
OUT OF THE PLAINS AND INTO THE MIDWEST VERSUS THE GFS WHICH KEEPS
THE UPPER LOW UP OVER THE NORTHERN TIER. MODELS DIVERGE EVEN MORE
SIGNIFICANTLY JUST BEYOND THE END OF THE FORECAST PERIOD. TENDENCY
IS TO LEAN TOWARDS THE TYPICALLY MORE ACCURATE...RELIABLE ECMWF WITH
RESPECT TO THE EVOLUTION OF THE UPPER AIR PATTERN.
AT THE SURFACE...AGAIN MODELS DIFFER CONSIDERABLY ON THE EVENTUAL
POSITION SOUTHERN EXTENT OF SURFACE COLD FRONTAL BOUNDARY ACROSS THE
OHIO VALLEY EARLY IN THE FORECAST. THE NAM/GFS BRINGS THE BOUNDARY
AS FAR SOUTH AS AN IND TO DAY LINE LATE THIS AFTERNOON AND/OR EARLY
FRIDAY MORNING RESPECTIVELY. THE ECMWF BRINGS THE BOUNDARY SOUTHWARD
TO BETWEEN DAY AND CVG BY EARLY SATURDAY MORNING...APPARENTLY WITH
SUPPORT FROM THE UPPER LEVEL WAVE THAT PUSHES THROUGH THE REGION.
END RESULT IS THAT THE BOUNDARY NEVER REALLY SEEMS TO MAKE IT AS FAR
SOUTH AS THE OHIO RIVER...IN A TRUE SUMMERTIME LIKE FASHION. THIS
DOES NOT BODE WELL FOR THE OPPORTUNITY OF RAIN UNLESS CONVECTION
ALONG THE FRONTAL BOUNDARY BECOMES MORE ORGANIZED AND MANAGES TO
MAKE A SURGE SOUTHWARD INTO OUR AREA. BEST OPPORTUNITY FOR THIS...
OR JUST SHOWER AND THUNDERSTORM ACTIVITY IN GENERAL WILL COME AS THE
UPPER LEVEL WAVE OR DISTURBANCE GRADUALLY SHIFTS THROUGH THE REGION
SATURDAY AND SUNDAY. TRENDED DRIER SUNDAY NIGHT THROUGH MONDAY NIGHT
WITH UPPER LEVEL RIDGING BUILDING INTO THE AREA. THREAT OF SHOWERS
AND THUNDERSTORMS INCREASE AGAIN TOWARDS THE END OF THE FORECAST
WINDOW...TUESDAY NIGHT AND/OR WEDNESDAY AND BEYOND AS SYSTEM MORE
THAN LIKELY MAKES A MOVE TOWARDS OUR AREA OUT OF THE NORTH CENTRAL
PLAINS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 725 AM EDT THU MAY 16 2013
VFR CONDITIONS WILL HOLD THROUGH THE TAF FORECAST PERIOD. A THREAT
OF THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON WITH THUNDERSTORMS
MOVING FROM THE NORTH IN THE JKL AREA AND FROM THE SOUTH FOR LOZ AND
SME. THERE IS ONLY AND SLIGHT CHANCE AT JKL AND A CHANCE AT SME AND
LOZ. THERE IS TOO MUCH UNCERTAINTY TO GO WITH A PREVAILING
THUNDERSTORM GROUP AS THE THUNDERSTORMS COULD STAY NORTH OR SOUTH AND
MAY NOT IMPACT THE TAF SITES.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...JJ
LONG TERM...RAY
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
857 AM EDT THU MAY 16 2013
.UPDATE...
ISSUED AT 857 AM EDT THU MAY 16 2013
CLOUDS HAVE INCREASED QUICKLY THIS MORNING...AND HAVE UPDATED THE
NDFD AND ZFP TO REFLECT THIS. MOSTLY CLOUDY SKIES NOW FORECAST ACROSS
THE ENTIRE AREA FOR TODAY. HRRR IS HANDLING CURRENT CONVECTION FAIRLY
WELL. 11Z HRRR POINTS TOWARDS A NORTH TO SOUTH RAIN PROBABILITY
CHANCE THIS AFTERNOON...WITH BEST CHANCE IN THE NORTH. WILL TAKE A
LOOK AT INCOMING 12Z DATA FOR ANY POSSIBLE UPDATES TO THE RAIN
PROBABILITIES FOR THIS AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
THERE ARE TWO MAIN INGREDIENTS TO THIS FORECAST WHICH INDIVIDUALLY
AND COLLECTIVELY ADD SOME DIFFICULTY TO THE FORECAST. THERE IS A COLD
FRONT SOUTH OF THE GREAT LAKES WHICH IS SAGGING TO THE SOUTH. THERE
IS ALSO AN UPPER LOW OVER OKLAHOMA EMBEDDED IS A WEAKER SOUTHERLY
STREAM. THESE TWO SYSTEMS ARE BOTH GOING TO BE EFFECTING THE WEATHER
OVER THE AREA OVER THE NEXT TWO DAYS. AT 230 AM THERE WAS A LINE OF
SHOWER AND THUNDERSTORMS WHICH EXTENDED FROM SOUTHWEST PENNSYLVANIA AND
THEN PASSED SOUTH OF COLUMBUS AND THEN ACROSS DAYTON. THIS SYSTEM
WILL BE SAGGING TO THE SOUTH. THE BIG QUESTION IS HOW FAR SOUTH WILL
THE FRONT MOVE. THE NAM STALLS THIS FRONT OUT ALONG THE OHIO RIVER
VALLEY. AS A RESULT...KEPT THE BEST CHANCE FOR RAIN TODAY AND
TONIGHT NORTH OF I 64 IN THE BLUEGRASS. THE MODELS ARE ALSO
GENERATING SOME ENERGY OUT AHEAD OF THE UPPER LOW WHICH WILL BE
MOVING TO THE EAST THE AREA SOUTH OF I 64 WILL BE IN THE GENERALLY
UNSTABLE WARM SECTOR TODAY AND TONIGHT WITH SOME ENERGY SPINNING
AROUND THE UPPER LOW WHICH MAY MOVE INTO THE AREA LATER TODAY. THIS
IS MOST LIKELY GOING TO EFFECT THE AREA SOUTH OF THE HAL ROGERS
PARKWAY. SO THERE IS A SLOT ACROSS THE CENTRAL PORTION OF EASTERN
KENTUCKY WHICH SHOULD BE SOUTH OF THE INFLUENCE OF THE FRONT AND
NORTH OF THE INFLUENCE OF THE UPPER LOW. THE ONE THING THAT IS A BIT
OF A WILD CARD IS IF THE THUNDERSTORMS TO THE NORTH ARE ABLE TO
CREATE A COLD POOL TODAY WHICH PROPAGATES SOUTH ACROSS EASTERN
KENTUCKY. THE NAM BUFFER SOUNDING HAS A LIFTED INDEX OF AROUND -5
THIS AFTERNOON...SO IF A COLD POOL DOES MOVE INTO THE AREA...THERE
WILL BE PLENTY OF INSTABILITY TO KEEP IT GOING. THE SCENARIO IS NOT
IN THE FORECAST...HOWEVER BEARS WATCHING.THERE SHOULD BE PLENTY OF
CLOUDS TODAY...HOWEVER THE LOWER LAYERS ARE FAIRLY DRY AND IT SHOULD
TAKE A WHILE TO BE ABLE TO MOISTEN THEM UP ENOUGH FOR THE RAIN TO
REACH THE GROUND. THE TEMPERATURES WILL BE SO DEPENDENT ON HOW
EXTENSIVE THE SHOWERS WILL BE TODAY. WENT A BIT WARMER THAN THE MODEL
CONSENSUS AND BLENDED CLOSER TO THE WARMER NAM MOS FOR TODAY AND
TOMORROW.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 AM EDT THU MAY 16 2013
MODE LS ARE IN FAIR AGREEMENT...BETTER WITH RELATIVELY SLOW BUT
PROGRESSIVE UPPER AIR PATTERN THAN WITH SURFACE FEATURES. EXTENDED
STARTS OUT WITH AN OPEN WAVE TRACKING EASTWARD ACROSS THE OHIO/TN
VALLEY REGIONS THROUGH THE WEEKEND. SHORTWAVE RIDGE THEN TRANSITS
THE REGION MONDAY BEFORE SLOW MOVING LOW PRESSURE SYSTEM OVER THE
NORTH CENTRAL PLAINS SHIFTS INTO THE MIDWEST...OR GREAT LAKES BY THE
END OF THE FORECAST WINDOW. WE FALL UNDER A SOUTHWEST FLOW REGIME
ALOFT DURING THE INTERIM. ECMWF...WITH SUPPORT FROM THE CANADIAN
APPEARS MORE ORGANIZED AND FURTHER SOUTH WITH THE UPPER LOW MOVING
OUT OF THE PLAINS AND INTO THE MIDWEST VERSUS THE GFS WHICH KEEPS
THE UPPER LOW UP OVER THE NORTHERN TIER. MODELS DIVERGE EVEN MORE
SIGNIFICANTLY JUST BEYOND THE END OF THE FORECAST PERIOD. TENDENCY
IS TO LEAN TOWARDS THE TYPICALLY MORE ACCURATE...RELIABLE ECMWF WITH
RESPECT TO THE EVOLUTION OF THE UPPER AIR PATTERN.
AT THE SURFACE...AGAIN MODELS DIFFER CONSIDERABLY ON THE EVENTUAL
POSITION SOUTHERN EXTENT OF SURFACE COLD FRONTAL BOUNDARY ACROSS THE
OHIO VALLEY EARLY IN THE FORECAST. THE NAM/GFS BRINGS THE BOUNDARY
AS FAR SOUTH AS AN IND TO DAY LINE LATE THIS AFTERNOON AND/OR EARLY
FRIDAY MORNING RESPECTIVELY. THE ECMWF BRINGS THE BOUNDARY SOUTHWARD
TO BETWEEN DAY AND CVG BY EARLY SATURDAY MORNING...APPARENTLY WITH
SUPPORT FROM THE UPPER LEVEL WAVE THAT PUSHES THROUGH THE REGION.
END RESULT IS THAT THE BOUNDARY NEVER REALLY SEEMS TO MAKE IT AS FAR
SOUTH AS THE OHIO RIVER...IN A TRUE SUMMERTIME LIKE FASHION. THIS
DOES NOT BODE WELL FOR THE OPPORTUNITY OF RAIN UNLESS CONVECTION
ALONG THE FRONTAL BOUNDARY BECOMES MORE ORGANIZED AND MANAGES TO
MAKE A SURGE SOUTHWARD INTO OUR AREA. BEST OPPORTUNITY FOR THIS...
OR JUST SHOWER AND THUNDERSTORM ACTIVITY IN GENERAL WILL COME AS THE
UPPER LEVEL WAVE OR DISTURBANCE GRADUALLY SHIFTS THROUGH THE REGION
SATURDAY AND SUNDAY. TRENDED DRIER SUNDAY NIGHT THROUGH MONDAY NIGHT
WITH UPPER LEVEL RIDGING BUILDING INTO THE AREA. THREAT OF SHOWERS
AND THUNDERSTORMS INCREASE AGAIN TOWARDS THE END OF THE FORECAST
WINDOW...TUESDAY NIGHT AND/OR WEDNESDAY AND BEYOND AS SYSTEM MORE
THAN LIKELY MAKES A MOVE TOWARDS OUR AREA OUT OF THE NORTH CENTRAL
PLAINS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 725 AM EDT THU MAY 16 2013
VFR CONDITIONS WILL HOLD THROUGH THE TAF FORECAST PERIOD. A THREAT
OF THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON WITH THUNDERSTORMS
MOVING FROM THE NORTH IN THE JKL AREA AND FROM THE SOUTH FOR LOZ AND
SME. THERE IS ONLY AND SLIGHT CHANCE AT JKL AND A CHANCE AT SME AND
LOZ. THERE IS TOO MUCH UNCERTAINTY TO GO WITH A PREVAILING
THUNDERSTORM GROUP AS THE THUNDERSTORMS COULD STAY NORTH OR SOUTH AND
MAY NOT IMPACT THE TAF SITES.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...JJ
LONG TERM...RAY
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
325 PM EDT THU MAY 16 2013
.SYNOPSIS...
HIGH PRESSURE REMAINS OFF THE COAST THROUGH THIS EVENING. A WEAK
FRONT MOVES SOUTH ACROSS VIRGINIA OVERNIGHT INTO FRIDAY
AFTERNOON...THEN STALLS OVER NORTH CAROLINA THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
SFC HI PRES RMNS OFF THE SE CONUS CST...WHILE A WK (ILL-DEFINED)
SFC BNDRY IS DRAPED E-W INVOF MD/PA BORDER WWD INTO SRN OH VLY.
VRY WARM AIR S OF THE BNDRY W/ MNLY WSWLY WNDS (A LTL GUSTY AT
TIMES TO ABT 20 MPH). CNVTN BEGINNING TO FIRE INVOF NW VA...JUST
NNW OF CHO...W/ ONLY ISOLD PCPN FOUND TO THE ENE INTO THE INTR
PORTION FO THE LWR MD ERN SHR. CNVTN HIGH BASED (~7KFT) AND
MODIFIED SOUNDINGS ACRS NRN PORTIONS OF FA SHOWING INVERTED V IN
LWR LVLS (TO ARND 850MB). SLGT POOLING OF DEWPTS (U50S) ACRS NRN VA
SO FAR THIS AFTN. ALSO...FREEZING LVL 11.5 TO 12KFT...WILL NEED
CORES OF ANY STMS TO AOA 30KFT FOR STRONG/SVR PTNTL. LMTG FACTOR
IS DP LYRD/DOWNSLOPING W WNDS PTNTLLY MAKING IT DIFFICULT FOR STM
UPDRAFTS TO RISE SUBSTANTIALLY. MAIN THREATS - GUSTY WINDS AND
HAIL. 17Z/16 RUC GENLY HAS DECENT HANDLING ON STM DVLPMNT
ATTM...AND HV FOLLOWED FOR EVE CNVTV POPS (WHICH CONFINES STMS TO
AREAS ALG-N OF A FVX TO WAL LN). S OF THAT LN ISOLD STMS AT
BEST...BUT RIGHT NOW PROB TOO LO FOR POPS ANY HIGHER THAN 14%.
AFT EVE STMS...BNDRY SINKS S THROUGH VA AND WINDS TURN MR NLY AFT
MDNGT. LINGERING SHRAS AFT MDNGT...THOUGH POPS AOB 20% THROUGHOUT.
LO TEMPS MNLY IN THE L/M60S.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
FNTL BNDRY STALLS OVR NRN VA ON FRI...W/ SFC HI PRES PASSING BY TO
THE NNE OF FA. RESULT WILL BE ONSHR SFC WNDS...AND CORRESPONDING
COOLING. WILL HAVE HIGHEST AMT OF CLDNS FM CNTRL VA ON S...AND LMT
CHC POPS TO MUCH OF THAT AREA (HIGHEST FAR SCNTRL VA INTO INTR NE
NC).
FM FRI NGT THROUGH SAT...WK LO PRES TRACKS E INTO THE CNTRL OH
VLY...RESULTING IN INCRSG MSTR INTO THE MDATLC RGN. FNTL BNDRY
RMNS S ACRS NRN NC...KEEPING ONSHR WNDS OVR MUCH OF THE FA
(THROUGH SAT). IN LEANING CLOSER TO 12Z/16 ECMWF WILL HAVE
HIGHEST (CHC) POPS INLAND FRI NGT THROUGH SAT...THOUGH WILL HAVE
VRB CLDNS OR MCLDY CONDS.
HI TEMPS FRI FM THE M/U70S AT THE CST TO L/M80S INLAND. LO TEMPS
FRI NGT FM THE M50S TO L60S. HI TEMPS SAT FM THE L/M70S AT THE
CST TO 75 TO 80F INLAND.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE MID-ATLANTIC SUNDAY
NIGHT INTO MONDAY. THIS IS IN ADDITION TO A WEAK UPPER DISTURBANCE
PASSING OVERHEAD WILL PRODUCE A CHANCE FOR SHOWERS AND
THUNDERSTORMS. AN H5 RIDGE AXIS SHOULD BUILD OVER THEN EASTERN U.S.
TUESDAY OF NEXT WEEK...THEN SLIDES OFF TO THE EAST LATE WEDNESDAY AS
THE NEXT SYSTEM BEGINS TO IMPACT THE MID-ATLANTIC. WILL MAINTAIN
SLIGHT CHC POPS ON TUESDAY DUE TO SOME UNCERTAINTY IN THE MODELS AS
TO WHETHER OR NOT THE UPPER DISTURBANCE PUSHES FAR ENOUGH OFF THE
COAST. THE NEXT SYSTEM LOOKS LIKE IT WILL BRING A GOOD CHANCE OF
SHOWERS BY LATE WEDNESDAY INTO NEXT THURSDAY. TEMPS WILL REMAIN ON
THE WARM/MILD SIDE THROUGH THE PERIOD WITH HIGHS IN THE 70S AND 80S
AND LOWS IN THE 60S.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
LOW PRESSURE CONTINUES TO TRACK THROUGH THE NORTHEAST TODAY AS AN
ATTENDANT COLD FRONT SLOWLY SAGS SWD INTO THE MID ATLANTIC. EXPECT
W/SW WINDS GENERALLY AROUND 10 KT WITH GUSTS UP TO 15 KT. AS THE
FRONT DROPS INTO NRN VA...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON INTO THIS EVENING
ACROSS THE REGION...GENERALLY NORTH OF THE NC/VA BORDER. MVFR/IFR
VSBYS POSSIBLE IN THUNDERSTORMS. HOWEVER...CONFIDENCE IN TIMING
AND PLACEMENT OF ANY STORMS IS NOT HIGH ATTM...SO HAVE ONLY
INCLUDED TEMPO GROUP MENTIONING RAIN SHOWERS.
THE COLD FRONT WILL CONTINUE TO SLOWLY PROGRESS SWD...CROSSING THE
REGION LATE TONIGHT THROUGH FRIDAY. WINDS WILL BACK FROM THE W/SW
TO THE NW BEHIND THE FRONT...BUT REMAIN AOB 10 KT. SHOWERS AND
THUNDERSTORMS WILL AGAIN BE POSSIBLE FRI AFTERNOON/EVENING...MAINLY
ACROSS SRN VA/NRN NC. THE FRONT WILL STALL OVER THE CAROLINAS THIS
WEEKEND...WITH ADDITIONAL SHOWERS AND THUNDERSTORMS POSSIBLE.
&&
.MARINE...
WINDS WILL CONTINUE TO VEER TO THE WEST THIS AFTERNOON IN ADVANCE OF
A BACKDOOR COLD FRONT. THE FRONT WILL SLOWLY CROSS THE WATERS
TONIGHT INTO FRIDAY. WINDS WILL VEER TO THE N/NE FRIDAY BEHIND THE
FRONT...BECOMING EAST IN THE AFTERNOON...BUT WILL REMAIN BELOW SCA
THRESHOLDS. THE COLD FRONT WILL STALL OVER THE CAROLINAS THIS
WEEKEND BEFORE LIFTING NWD AS A WARM FRONT BY THE BEGINNING OF NEXT
WEEK. E/SE WINDS LESS THAN 15 KT ARE EXPECTED OVER THE WEEKEND. SEAS
MAY BUILD TO 5 FT OVER THE NORTHERN COASTAL WATERS ON SUNDAY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ALB/MPR
NEAR TERM...ALB/MPR
SHORT TERM...MPR
LONG TERM...JDM
AVIATION...SAM/DAP
MARINE...JDM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
314 PM EDT THU MAY 16 2013
.SYNOPSIS...
HIGH PRESSURE REMAINS OFF THE COAST THROUGH THIS EVENING. A WEAK
FRONT MOVES SOUTH ACROSS VIRGINIA OVERNIGHT INTO FRIDAY
AFTERNOON...THEN STALLS OVER NORTH CAROLINA THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
SFC HI PRES RMNS OFF THE SE CONUS CST...WHILE A WK (ILL-DEFINED)
SFC BNDRY IS DRAPED E-W INVOF MD/PA BORDER WWD INTO SRN OH VLY.
VRY WARM AIR S OF THE BNDRY W/ MNLY WSWLY WNDS (A LTL GUSTY AT
TIMES TO ABT 20 MPH). CNVTN BEGINNING TO FIRE INVOF NW VA...JUST
NNW OF CHO...W/ ONLY ISOLD PCPN FOUND TO THE ENE INTO THE INTR
PORTION FO THE LWR MD ERN SHR. CNVTN HIGH BASED (~7KFT) AND
MODIFIED SOUNDINGS ACRS NRN PORTIONS OF FA SHOWING INVERTED V IN
LWR LVLS (TO ARND 850MB). SLGT POOLING OF DEWPTS (U50S) ACRS NRN VA
SO FAR THIS AFTN. ALSO...FREEZING LVL 11.5 TO 12KFT...WILL NEED
CORES OF ANY STMS TO AOA 30KFT FOR STRONG/SVR PTNTL. LMTG FACTOR
IS DP LYRD/DOWNSLOPING W WNDS PTNTLLY MAKING IT DIFFICULT FOR STM
UPDRAFTS TO RISE SUBSTANTIALLY. MAIN THREATS - GUSTY WINDS AND
HAIL. 17Z/16 RUC GENLY HAS DECENT HANDLING ON STM DVLPMNT
ATTM...AND HV FOLLOWED FOR EVE CNVTV POPS (WHICH CONFINES STMS TO
AREAS ALG-N OF A FVX TO WAL LN). S OF THAT LN ISOLD STMS AT
BEST...BUT RIGHT NOW PROB TOO LO FOR POPS ANY HIGHER THAN 14%.
AFT EVE STMS...BNDRY SINKS S THROUGH VA AND WINDS TURN MR NLY AFT
MDNGT. LINGERING SHRAS AFT MDNGT...THOUGH POPS AOB 20% THROUGHOUT.
LO TEMPS MNLY IN THE L/M60S.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
FNTL BNDRY STALLS OVR NRN VA ON FRI...W/ SFC HI PRES PASSING BY TO
THE NNE OF FA. RESULT WILL BE ONSHR SFC WNDS...AND CORRESPONDING
COOLING. WILL HAVE HIGHEST AMT OF CLDNS FM CNTRL VA ON S...AND LMT
CHC POPS TO MUCH OF THAT AREA (HIGHEST FAR SCNTRL VA INTO INTR NE
NC).
FM FRI NGT THROUGH SAT...WK LO PRES TRACKS E INTO THE CNTRL OH
VLY...RESULTING IN INCRSG MSTR INTO THE MDATLC RGN. FNTL BNDRY
RMNS S ACRS NRN NC...KEEPING ONSHR WNDS OVR MUCH OF THE FA
(THROUGH SAT). WILL HAVE HIGHEST POPS INLAND THROUGH SAT...THOUGH
WILL HAVE VRB CLDNS OR MCLDY CONDS.
HI TEMPS FRI FM THE M/U70S AT THE CST TO L/M80S INLAND. LO TEMPS
FRI NGT FM THE M50S TO L60S. HI TEMPS SAT FM THE L/M70S AT THE
CST TO 75 TO 80F INLAND.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE MID-ATLANTIC SUNDAY
NIGHT INTO MONDAY. THIS IS IN ADDITION TO A WEAK UPPER DISTURBANCE
PASSING OVERHEAD WILL PRODUCE A CHANCE FOR SHOWERS AND
THUNDERSTORMS. AN H5 RIDGE AXIS SHOULD BUILD OVER THEN EASTERN U.S.
TUESDAY OF NEXT WEEK...THEN SLIDES OFF TO THE EAST LATE WEDNESDAY AS
THE NEXT SYSTEM BEGINS TO IMPACT THE MID-ATLANTIC. WILL MAINTAIN
SLIGHT CHC POPS ON TUESDAY DUE TO SOME UNCERTAINTY IN THE MODELS AS
TO WHETHER OR NOT THE UPPER DISTURBANCE PUSHES FAR ENOUGH OFF THE
COAST. THE NEXT SYSTEM LOOKS LIKE IT WILL BRING A GOOD CHANCE OF
SHOWERS BY LATE WEDNESDAY INTO NEXT THURSDAY. TEMPS WILL REMAIN ON
THE WARM/MILD SIDE THROUGH THE PERIOD WITH HIGHS IN THE 70S AND 80S
AND LOWS IN THE 60S.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
LOW PRESSURE CONTINUES TO TRACK THROUGH THE NORTHEAST TODAY AS AN
ATTENDANT COLD FRONT SLOWLY SAGS SWD INTO THE MID ATLANTIC. EXPECT
W/SW WINDS GENERALLY AROUND 10 KT WITH GUSTS UP TO 15 KT. AS THE
FRONT DROPS INTO NRN VA...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON INTO THIS EVENING
ACROSS THE REGION...GENERALLY NORTH OF THE NC/VA BORDER. MVFR/IFR
VSBYS POSSIBLE IN THUNDERSTORMS. HOWEVER...CONFIDENCE IN TIMING
AND PLACEMENT OF ANY STORMS IS NOT HIGH ATTM...SO HAVE ONLY
INCLUDED TEMPO GROUP MENTIONING RAIN SHOWERS.
THE COLD FRONT WILL CONTINUE TO SLOWLY PROGRESS SWD...CROSSING THE
REGION LATE TONIGHT THROUGH FRIDAY. WINDS WILL BACK FROM THE W/SW
TO THE NW BEHIND THE FRONT...BUT REMAIN AOB 10 KT. SHOWERS AND
THUNDERSTORMS WILL AGAIN BE POSSIBLE FRI AFTERNOON/EVENING...MAINLY
ACROSS SRN VA/NRN NC. THE FRONT WILL STALL OVER THE CAROLINAS THIS
WEEKEND...WITH ADDITIONAL SHOWERS AND THUNDERSTORMS POSSIBLE.
&&
.MARINE...
WINDS WILL CONTINUE TO VEER TO THE WEST THIS AFTERNOON IN ADVANCE OF
A BACKDOOR COLD FRONT. THE FRONT WILL SLOWLY CROSS THE WATERS
TONIGHT INTO FRIDAY. WINDS WILL VEER TO THE N/NE FRIDAY BEHIND THE
FRONT...BECOMING EAST IN THE AFTERNOON...BUT WILL REMAIN BELOW SCA
THRESHOLDS. THE COLD FRONT WILL STALL OVER THE CAROLINAS THIS
WEEKEND BEFORE LIFTING NWD AS A WARM FRONT BY THE BEGINNING OF NEXT
WEEK. E/SE WINDS LESS THAN 15 KT ARE EXPECTED OVER THE WEEKEND. SEAS
MAY BUILD TO 5 FT OVER THE NORTHERN COASTAL WATERS ON SUNDAY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ALB/MPR
NEAR TERM...ALB/MPR
SHORT TERM...MPR
LONG TERM...JDM
AVIATION...SAM/DAP
MARINE...JDM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
236 PM EDT THU MAY 16 2013
.SYNOPSIS...
HIGH PRESSURE REMAINS OFF THE COAST THROUGH THIS EVENING. A WEAK
FRONT MOVES SOUTH ACROSS VIRGINIA OVERNIGHT INTO FRIDAY
AFTERNOON...THEN STALLS OVER NORTH CAROLINA THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
SFC HI PRES RMNS OFF THE SE CONUS CST...WHILE A WK (ILL-DEFINED)
SFC BNDRY IS DRAPED E-W INVOF MD/PA BORDER WWD INTO SRN OH VLY.
VRY WARM AIR S OF THE BNDRY W/ MNLY WSWLY WNDS (A LTL GUSTY AT
TIMES TO ABT 20 MPH). CNVTN BEGINNING TO FIRE INVOF NW VA...JUST
NNW OF CHO...W/ ONLY ISOLD PCPN FOUND TO THE ENE INTO THE INTR
PORTION FO THE LWR MD ERN SHR. CNVTN HIGH BASED (~7KFT) AND
MODIFIED SOUNDINGS ACRS NRN PORTIONS OF FA SHOWING INVERTED V IN
LWR LVLS (TO ARND 850MB). SLGT POOLING OF DEWPTS (U50S) ACRS NRN VA
SO FAR THIS AFTN. ALSO...FREEZING LVL 11.5 TO 12KFT...WILL NEED
CORES OF ANY STMS TO AOA 30KFT FOR STRONG/SVR PTNTL. LMTG FACTOR
IS DP LYRD/DOWNSLOPING W WNDS PTNTLLY MAKING IT DIFFICULT FOR STM
UPDRAFTS TO RISE SUBSTANTIALLY. MAIN THREATS - GUSTY WINDS AND
HAIL. 17Z/16 RUC GENLY HAS DECENT HANDLING ON STM DVLPMNT
ATTM...AND HV FOLLOWED FOR EVE CNVTV POPS (WHICH CONFINES STMS TO
AREAS ALG-N OF A FVX TO WAL LN). S OF THAT LN ISOLD STMS AT
BEST...BUT RIGHT NOW PROB TOO LO FOR POPS ANY HIGHER THAN 14%.
AFT EVE STMS...BNDRY SINKS S THROUGH VA AND WINDS TURN MR NLY AFT
MDNGT. LINGERING SHRAS AFT MDNGT...THOUGH POPS AOB 20% THROUGHOUT.
LO TEMPS MNLY IN THE L/M60S.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
FRNTL BNDRY SLOWLY DRIFTS S ACROSS SRN VA TONITE. ENUF SPRT TO KEEP
LOW CHC POPS...MAINLY IN THE EVE ALTHOUGH SOME SHWR ACTIVITY MAY
LINGER IVOF BNDRY AFTR MIDNITE. LOWS 60-65.
MODELS PROG FRNTL BNDRY TO STALL INVOF NRN NC LATE FRI THROUGH
SAT. MEANWHILE...SFC HIGH PRS MOVG ACROSS NEW ENGLAND LEADS TO
ONSHR WINDS. UPSHOT...AN UNSETTLED PRD XPCTD WITH SKIES VRBLY TO M
CLDY WITH PERIODIC PCPN CHCS. LOWEST POPS ACROSS ERN SHORE AND NRN
NECK AS DRYER AIR MOVES SOUTH FROM HIGH PRS TO THE NRTH. HIGHEST
POPS ACROSS WEST AND SRN AREAS CLOSER TO THE FRNT. MSTR INCRS FROM
THE WEST SAT ENHANCING PCPN CHCS ON ACROSS WRN CNTYS.
FRIDAYS TMP FCST A BIT TRICKY. ALL DEPENDS ON FRNTL LCTN AND PCPN.
HIGHS M-U70S CSTL AREAS...80-85 WEST OF BAY. LOWS FRI NITE 55-60.
HIGHS SAT L-M70S...XCPT 75-80 SRN MOST CNTYS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE MID-ATLANTIC SUNDAY.
THIS IS IN ADDITION TO A WEAK UPPER DISTURBANCE PASSING OVERHEAD
WILL PRODUCE A CHANCE FOR SHOWERS AND THUNDERSTORMS. AN H5 RIDGE
AXIS BUILDS OVER THEN EASTERN U.S. MON-WED OF NEXT WEEK. MODELS SHOW
A LOT OF UNCERTAINTY AS TO JUST HOW MUCH SHOWER/TSTM ACTIVITY WILL
OCCUR EARLY NEXT WEEK. DUE TO A LACK OF A TRIGGER TO GET ORGANIZED
TSTMS GOING...WILL LIMIT PCPN CHANCES TO THE 20-30% RANGE REACH DAY.
TEMPS WILL REMAIN ON THE WARM/MILD SIDE THROUGH THE PERIOD WITH
HIGHS IN THEN 70S AND 80S AND LOWS IN THE 60S.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
LOW PRESSURE CONTINUES TO TRACK THROUGH THE NORTHEAST TODAY AS AN
ATTENDANT COLD FRONT SLOWLY SAGS SWD INTO THE MID ATLANTIC. EXPECT
W/SW WINDS GENERALLY AROUND 10 KT WITH GUSTS UP TO 15 KT. AS THE
FRONT DROPS INTO NRN VA...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON INTO THIS EVENING
ACROSS THE REGION...GENERALLY NORTH OF THE NC/VA BORDER. MVFR/IFR
VSBYS POSSIBLE IN THUNDERSTORMS. HOWEVER...CONFIDENCE IN TIMING
AND PLACEMENT OF ANY STORMS IS NOT HIGH ATTM...SO HAVE ONLY
INCLUDED TEMPO GROUP MENTIONING RAIN SHOWERS.
THE COLD FRONT WILL CONTINUE TO SLOWLY PROGRESS SWD...CROSSING THE
REGION LATE TONIGHT THROUGH FRIDAY. WINDS WILL BACK FROM THE W/SW
TO THE NW BEHIND THE FRONT...BUT REMAIN AOB 10 KT. SHOWERS AND
THUNDERSTORMS WILL AGAIN BE POSSIBLE FRI AFTERNOON/EVENING...MAINLY
ACROSS SRN VA/NRN NC. THE FRONT WILL STALL OVER THE CAROLINAS THIS
WEEKEND...WITH ADDITIONAL SHOWERS AND THUNDERSTORMS POSSIBLE.
&&
.MARINE...
LATEST SFC OBS SHOW SW WINDS OVER THE WATERS WITH SPEEDS GENERALLY
AROUND 15 KT. SEAS OVER THE NRN COASTAL WATERS RUNNING 3 TO 5 FT.
PRESSURE GRADIENT HAS BEGUN TO RELAX BETWEEN HIGH PRESSURE OFF THE
SE COAST AND LOW PRESSURE TRACKING ACROSS SE CANADA...BUT SPEEDS OF
25 TO 30 KT OBSERVED (KWAL SOUNDING) ABOUT 1K OFF THE SFC OF THE
WATER. PRESSURE GRADIENT WILL CONTINUE TO RELAX THROUGH THIS
MORNING...ALLOWING SPEEDS TO DIMINISH AOB 10 KT THROUGH THE
AFTERNOON. SEAS WILL ALSO FALL AOB 3 FT. WITH THAT SAID...HAVE
DROPPED SCA HEADLINES FOR THE BAY...BUT SPEEDS AROUND 15 KT WILL
CONTINUE THROUGH MID MORNING. SCA HEADLINES WILL CONTINUE FOR THE
NRN COASTAL ZONES THROUGH 7AM FOR HIGH SEAS. WINDS WILL SLOWLY BACK
TO THE W THIS AFTERNOON IN ADVANCE OF A BACKDOOR COLD FRONT. THE
COLD FRONT WILL SLOWLY PROGRESS SWD INTO NRN VA TODAY...CROSSING THE
WATER TONIGHT INTO FRIDAY. WINDS WILL BACK TO THE W/NW TO N/NE
FRIDAY...BUT REMAIN SUB SCA. THE COLD FRONT WILL STALL OVER THE
CAROLINAS THIS WEEKEND BEFORE LIFTING NWD AS A WARM FRONT THE
BEGINNING OF NEXT WEEK. E/SE WINDS LESS THAN 15 KT ARE EXPECTED OVER
THE WEEKEND.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ALB/MPR
NEAR TERM...ALB/MPR
SHORT TERM...MPR
LONG TERM...JDM
AVIATION...SAM/DAP
MARINE...JDM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
131 AM EDT THU MAY 16 2013
.SYNOPSIS...
HIGH PRESSURE REMAINS CENTERED OFF THE MID ATLANTIC COAST THROUGH
FRIDAY. A WEAK FRONT APPROACHES THE AREA FROM THE NORTH THURSDAY
AFTERNOON THEN SETTLES OVER THE AREA FRIDAY INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE LATEST SURFACE ANALYSIS INDICATES A ~1022MB SURFACE HIGH
CENTERED OVER THE EAST-CENTRAL GULF COAST, WITH A SURFACE RIDGE
AXIS EXTENDING NE JUST OFF THE SOUTHEAST COAST. ALOFT, A RATHER
PROGRESSIVE NORTHERN STREAM FLOW EXISTS, WITH QUASI-ZONAL FLOW
ACROSS THE NORTHERN TIER OF STATES. MEANWHILE, WEAK SHORTWAVE
RIDGING HAS DEVELOPED ACROSS THE SOUTHEAST AHEAD OF CLOSED UPPER
LOW WHICH CONTINUES TO SLOWLY MEANDER ACROSS THE SOUTHERN PLAINS.
A WEAK DISTURBANCE DROPPING SE OF THE LOWER GRT LAKES HAVE
TRIGGERED A FEW ISOLATED SHRAS THIS EVENING, MAINLY ALONG AND
JUST SOUTH OF THE MASON-DIXON LINE INVOF FNTL BNDRY DRAPED NW-SE
FM SOUTH CENTRAL PA TO OH VLY THIS EVE. HRRR CONTINUES TO WEAKEN
THIS ACTIVITY JUST TO OUR NORTH, THOUGH POTENTIAL DOES EXIST FOR
AN ISOLATED SHRA OR TWO OVER FAR NORTHERN PART OF DORCHESTER,
WICOMICO, AND WORCESTER COUNTIES (US-50 AND NORTH) THROUGH ABOUT
6Z/2A OR SO BEFORE IT AND THE ASSD WARM FRONT CLEAR THE NORTHERN
MID-ATLANTIC COAST LATE TONIGHT. OTHERWISE, LOOK FOR A MILD,
COMFORTABLE OVERNIGHT, UNDER A CLEAR TO PARTLY CLOUDY SKY. EARLY
MORNING LOW TEMPS MAINLY IN THE L/M60S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/...
FNTL BNDRY FM THE N BEGINS TO PUSH SLOLY S THU...REACHING NRN
AREAS OF FA IN THE AFTN...THEN TO THE S THU NGT INTO FRI. NOT THE
BEST FORCING OR DYNAMICS FOR ORGANIZED CNVTN...THOUGH SOME POOLING
OF SFC-LO LVL DEWPTS COMBINED W/ HEATING PTNTLLY ENOUGH FOR
ISOLD/SCT CNVTN. WILL CARRY 20-40% POPS ACRS THE FA THU AFTN INTO
THU NGT. THE BNDRY SHIFTS S TO NR OR JUST S OF THE NC/VA BRDR ON
FRI...W/ PSBL FOCUS FOR ANY PCPN FM CNTRL/SRN VA INTO NE NC. WHILE
ENOUGH TIME FOR DECENT WRMG ON THU (BEFORE THE BNDRY REACHES THE
FA)...WILL BE ABLE TO HAVE TEMPS REACH THE 80S XCP RIGHT AT THE
CST (ON THE ERN SHR). PSNY THU...THEN VRB CLDS OR MCLDY THU NGT
INTO FRI.
THE BNDRY TO RMN NRLY STNRY INVOF NRN NC LT FRI THROUGH SAT. SFC
HI PRES PASSING BY N AND THROUGH NEW ENG WILL LEAD TO ONSHR
WINDS...CONTD VRB CLDS OR MCLDY CONDS AND LO PROB FOR PCPN. HI
TEMPS SAT FM ARND 70F AT THE CST...TO MNLY THE M/U70S INLAND.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE MID-ATLANTIC SUNDAY.
THIS IS IN ADDITION TO A WEAK UPPER DISTURBANCE PASSING OVERHEAD
WILL PRODUCE A CHANCE FOR SHOWERS AND THUNDERSTORMS. AN H5 RIDGE
AXIS BUILDS OVER THEN EASTERN U.S. MON-WED OF NEXT WEEK. MODELS SHOW
A LOT OF UNCERTAINTY AS TO JUST HOW MUCH SHOWER/TSTM ACTIVITY WILL
OCCUR EARLY NEXT WEEK. DUE TO A LACK OF A TRIGGER TO GET ORGANIZED
TSTMS GOING...WILL LIMIT PCPN CHANCES TO THE 20-30% RANGE REACH DAY.
TEMPS WILL REMAIN ON THE WARM/MILD SIDE THROUGH THE PERIOD WITH
HIGHS IN THEN 70S AND 80S AND LOWS IN THE 60S.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
LOW PRESSURE WILL TRACK THROUGH SE CANADA TODAY AS AN ATTENDANT
COLD FRONT SLOWLY SAGS SWD INTO THE MID ATLANTIC. HIGH PRESSURE WILL
REMAIN OFF THE SOUTHEAST COAST. GENERALLY CLEAR SKIES THIS
MORNING...EXCEPT MID/UPPER LEVEL CLOUDS ASSOCIATED WITH THE FRONT
MOVING ACROSS NRN VA AND THE MD ERN SHORE. SW WINDS GENERALLY AOB
10 KT THIS MORNING WITH A FEW GUSTS UP TO 25 KT ALONG THE
IMMEDIATE COAST. FOR TODAY...NOT AS BREEZY AS WEDS AFTERNOON WITH
W/SW WINDS GENERALLY AROUND 10 TO 15 KT WITH GUSTS UP TO 20 KT. AS
THE FRONT DROPS INTO NRN VA THIS AFTERNOON...ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON INTO
THIS EVENING ACROSS THE REGION...GENERALLY NORTH OF THE NC/VA
BORDER. MVFR/IFR VSBYS POSSIBLE IN THUNDERSTORMS WITH GUSTS UP TO
35 KT. HOWEVER...CONFIDENCE IS NOT HIGH ATTM DUE TO LACK OF
COVERAGE...SO WILL NOT INCLUDE IN TAFS.
THE COLD FRONT WILL CONTINUE TO SLOWLY PROGRESS SWD...CROSSING THE
REGION LATE TONIGHT THROUGH FRIDAY. WINDS WILL BACK FROM THE W/SW
TO THE NW BEHIND THE FRONT. SHOWERS AND THUNDERSTORMS WILL AGAIN
BE POSSIBLE FRI AFTERNOON/EVENING...MAINLY ACROSS SRN VA/NRN NC.
THE FRONT WILL STALL OVER THE CAROLINAS THIS WEEKEND...WITH
ADDITIONAL SHOWERS AND THUNDERSTORMS POSSIBLE.
&&
.MARINE...
S-SW FLOW CONTINUES ACROSS THE MARINE AREA THROUGH LATE THIS EVENING
WITH MARGINAL SMALL CRAFT CONDITIONS (SAVE THE SOUTHERN COASTAL
WATERS). WILL LEAVE CURRENT HEADLINES UNCHANGED. WINDS TURN SW TO W
LATE TONIGHT AND DECREASE IN ADVANCE OF A BACKDOOR COLD FRONT THAT
SLOWLY SAGS SOUTHWARD THURS...CROSSING THE WATERS THURS NIGHT INTO FRI
BEFORE STALLING OVER THE CAROLINAS. WINDS WILL SHIFT FROM THE SW TO
THE N/NE POST FRONTAL...BUT EXPECTED TO REMAIN BELOW SCA THRESHOLDS.
E-SE WINDS LESS THAN 15 KT ARE EXPECTED OVER THE WEEKEND.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR
ANZ630>632-634.
SMALL CRAFT ADVISORY UNTIL 7 AM EDT THIS MORNING FOR ANZ650-
652-654.
&&
$$
SYNOPSIS...ALB/MPR
NEAR TERM...ALB
SHORT TERM...MPR
LONG TERM...JDM
AVIATION...SAM
MARINE...JDM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
422 PM EDT THU MAY 16 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 421 PM EDT THU MAY 16 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW TROFFING ALONG THE W COAST
OF THE CONUS...BROAD RIDGING OVER THE CNTRL CONUS...AND A TROF
EXTENDING S INTO NEW ENGLAND. AHEAD OF THE RIDGE...IT`S BEEN A
GENERALLY SUNNY DAY ACROSS THE FCST AREA. WITH THE DRY AIR NOTED ON
THE 12Z KGRB SOUNDING...DWPTS HAVE FALLEN INTO THE 20S OVER PORTIONS
OF THE INTERIOR W HALF OF UPPER MI...RESULTING IN RH DOWN AROUND
20PCT. SFC HIGH PRES ASSOCIATED WITH APPROACHING MID LEVEL RIDGE IS
SETTLING S OVER THE UPPER GREAT LAKES AND WILL LEAD TO A QUIET NIGHT
TONIGHT. TO THE W...A COUPLE OF SHORTWAVES EMERGING OVER THE WRN
HIGH PLAINS ARE GENERATING SHRA/TSRA FROM ND TO NEBRASKA. THE SRN
WAVE OVER WRN NEBRASKA IS THE STRONGER ONE. HEADING INTO LATER
FRI...FCST WILL REVOLVE AROUND WHAT AFFECTS THESE WAVES WILL HAVE
FOR UPPER MI.
AS ALLUDED TO ABOVE...SFC HIGH PRES WILL LEAD TO A TRANQUIL NIGHT
ACROSS THE FCST AREA. MAINLY CLEAR SKIES WITH PRECIPITABLE WATER
AROUND 50PCT OF NORMAL WILL LEAD TO A QUICK TEMP DROP AFTER SUNSET.
COLUMN MOISTURE BEGINS TO INCREASE OVER THE W OVERNIGHT...AND SOME
OF THAT WILL MANIFEST ITSELF AS HIGH AND MID CLOUDS SPREADING E FROM
THE SHRA AREA CURRENTLY OVER THE DAKOTAS. IN THE END...THIS SHOULD
LEAD TO LOWEST MINS OVER THE E...THOUGH SOME OF THE TRADITIONAL COLD
SPOTS OVER THE W MAY BE EQUALLY AS LOW GIVEN THE GOOD RADIATIONAL
COOLING CONDITIONS EARLY IN THE NIGHT. GENERALLY FAVORED THE LOWER
END OF GUIDANCE ACROSS THE BOARD IN THE INTERIOR. A FEW OF THE
TYPICAL COLD SPOTS MAY SLIP JUST BLO 30F.
WHETHER ANY PCPN MAKES INTO THE FCST AREA FRI IS THE BIG QUESTION.
THE NAM IS VERY AGRESSIVE WITH PCPN...BRINGING OVER AN INCH OF RAIN
TO KIWD BY 00Z SAT WITH PCPN SPREADING AS FAR E AS SENEY. THE GFS
FOLLOWS CLOSE BEHIND THE NAM...THOUGH ITS PCPN FIELD IS DISPLACED A
LITTLE FARTHER S. THE GEM HAS NO PCPN THRU 00Z SAT...THE UKMET ONLY
BRINGS A FEW HUNDREDTHS TO SCNTRL UPPER MI...AND THE 12Z ECMWF IS
SIMILAR WITH A FEW HUNDREDTHS ALONG THE WI BORDER WHICH IS FARTHER S
AND W THAN ITS 00Z RUN. SUSPECT THE STRONGER MORE WELL-DEFINED SRN
WAVE OVER THE WRN PLAINS WILL BE THE BIGGER PLAYER...RESULTING IN
PCPN WITH THE NRN WAVE OVER ND GRADUALLY DRYING UP AS IT WILL HAVE
LIMITED/NO MOISTURE INFLOW AND IT WILL BE ENCOUNTERING DRIER AIR TO
THE E. EVEN PCPN WITH THE SRN WAVE WILL PROBABLY TEND TO DIMINISH OR
AT LEAST BE SLOWER TO ARRIVE DUE TO THE DRIER AIR OVER GREAT
LAKES...ESPECIALLY SINCE LOW-LEVEL TRAJECTORIES HAVE A GOOD EASTERLY
COMPONENT FRI THAT WILL HELP TO MAINTAIN DRY AIR OVER THE AREA. SO
PLAN WILL BE TO FAVOR THE DRIER NON NCEP MODELS FOR FRI. WHILE
RELUCTANT TO ADD PCPN CHC...WILL INCLUDE A SCHC MENTION ALONG THE WI
BORDER SINCE THE THERE WAS ONLY ONE MODEL (GEM) THAT HAD A
COMPLETELY DRY FCST. FOLLOWING THE DRIER SCENARIO...ALSO UTILIZED
LOWER DWPTS FOR FRI BY COMBINING SOME OF THE BIAS CORRECTED GUIDANCE
(GEM IN PARTICULAR) WITH DWPTS CALCULATED BASED ON MIXING HEIGHT.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 421 PM EDT THU MAY 16 2013
CONFIDENCE IS STILL RATHER LOW ON QPF POTENTIAL FRIDAY NIGHT INTO
SATURDAY ASSOCIATED WITH THE DEVELOPING BAROCLINIC ZONE. AS THE
850MB LOW OVER THE CENTRAL AND NORTHERN ROCKIES MOVES EAST...STRONG
WARM ADVECTION AND ISENTROPIC LIFT WILL SPREAD ACROSS THE UPPER
MIDWEST. THE NAM IS VERY AGGRESSIVE IN DEVELOPING SIGNIFICANT
ELEVATED CONVECTION CLOSE TO THE MI/WI BORDER LATE FRI AFTN INTO
FRIDAY NIGHT...WITH OVER 2 INCHES OF QPF FORECAST AT IMT AND IWD BY
SAT AFTN. THE 12Z GFS HAS SHIFTED THE BAROCLINIC AXIS
NORTHWARD...BUT IT IS NOT AS STRONG AS THE NAM. THE 00Z ECMWF IS
OVERALL THE WEAKEST WITH THE FRONTAL BOUNDARY BUT NONETHELESS IS
SIMILAR IN POSITION BUT A LITTLE SLOWER (SIMILAR TO WHAT THE 18Z NAM
SHOWS). THE GEM IS MUCH FURTHER SOUTH. WITH ALL THAT SAID...THE
CONSENSUS OF DETERMINISTIC AND ENSEMBLE NWP SUGGEST THAT POPS WILL
NEED TO BE RAISED ACROSS THE ENTIRE AREA (EXCEPT EAST 1/3) FRIDAY
NIGHT INTO SATURDAY. WITH THE STRONGLY CONFLUENT FLOW AND DRY AIR IN
PLACE...DO NOT EXPECT THE HEAVY PCPN PER THE NAM FORECAST...HOWEVER
SOME SHOWER ACTIVITY FRIDAY NIGHT INTO SATURDAY IS EXPECTED
ESPECIALLY CLOSER TO THE WI BORDER WHERE THE BETTER MOISTURE AND
BETTER LIFT ASSOCIATED WITH THE FRONTAL ZONE IS LOCATED.
BY SATURDAY AFTERNOON...THE BAROCLINIC ZONE SHIFTS NORTH OF THE AREA
WITH THE BEST MOISTURE TRANSPORT CLOSER TO THE LOW TO THE WEST OF
THE AREA. IN FACT...WILL LIKELY SEE SOME CLEARING LATE SAT AFTN AS
THE WARM SECTOR MOVES OVER THE AREA AND DRIER AIR ADVECTS INTO THE
AREA. WILL MAINTAIN LOW CHANCE POPS WEST SAT AFTN/NIGHT...BUT
GENERALLY DRY ELSEWHERE.
SUNDAY SHOULD END UP BEING GENERALLY DRY WITH THE BEST MOISTURE AND
LOW LVL JET TO THE WEST OF THE AREA. NAM AND GFS ARE VERY AGGRESSIVE
IN WARMING 850MB TEMPS TO +18C ACROSS THE SOUTH...BUT AM THINKING
THE MORE CONSERVATIVE ECMWF WITH 850MB TEMPS AROUND +14 SEEMS MORE
REASONABLE. REGARDLESS...SHOULD BE A NICE DAY WITH PERHAPS A CHANCE
OF SHOWERS AND THUNDERSTORMS LATE IN THE DAY SUNDAY ACROSS THE WEST.
RATHER UNSETTLED WEATHER WILL CONTINUE THROUGH THE EARLY PART OF
NEXT WEEK WITH THE UPPER LOW OVER THE NORTHERN PLAINS BEING RATHER
STUBBORN TO MOVE OUT. THIS WILL KEEP THE BAROCLINIC ZONE NEARBY
THROUGH WEDNESDAY BEFORE AN UPPER TROUGH OVER HUDSON BAY DIVES SOUTH
AND ALLOWS THE FRONT TO MOVE SOUTH OF THE AREA BY THURSDAY. WITH
THAT SAID...MON-WED LOOKS QUITE WET AT TIMES WITH SOME HEAVY RAIN
CERTAINLY POSSIBLE. ALTHOUGH 850MB TEMPS WILL BE AROUND +10C THROUGH
WED...EASTERLY FLOW DUE TO THE LOW STAYING SOUTH OF THE AREA AS WELL
AS PLENTIFUL CLOUDS WILL KEEP TEMPS COOL NEAR LAKE SUPERIOR. INLAND
TEMPS WILL LIKELY STAY NEAR NORMAL...BUT TEMPS CLOSER TO LAKE
SUPERIOR WILL BE IN THE UPPER 50S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 140 PM EDT THU MAY 16 2013
VFR CONDITIONS WILL PREVAIL AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD
AS HIGH PRES MAINTAINS DRY LOW-LEVELS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EDT THU MAY 16 2013
LIGHT WINDS WILL BE THE RULE ACROSS LAKE SUPERIOR TONIGHT WITH HIGH
PRES OVER THE UPPER LAKES. WHILE THE HIGH WILL BE SHIFTING E FRI...A
MESO HIGH MAY LINGER OVER ERN LAKE SUPERIOR THRU THE DAY. THIS WILL
KEEP WINDS LIGHT OVER THE E...BUT E TO NE WINDS WILL BEGIN TO
INCREASE OVER THE W. HEADING THRU THE WEEKEND INTO EARLY NEXT
WEEK...PRES GRADIENT OVER THE UPPER LAKES WILL SLOWLY TIGHTEN BTWN
LOW PRES SLOWLY MOVING FROM THE WRN PLAINS TOWARD THE UPPER
MISSISSIPPI VALLEY AND HIGH PRES BUILDING IN THE VCNTY OF WRN HUDSON
BAY. THIS WILL LEAD TO EASTERLY WINDS GRADUALLY INCREASING INTO
GENERALLY THE 15-25KT RANGE. COULD BE SOME PERIODS OF HIGHER WINDS
AT TIMES EARLY NEXT WEEK...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...MRD
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GAYLORD MI
130 PM EDT THU MAY 16 2013
.SYNOPSIS...
ISSUED AT 353 AM EDT THU MAY 16 2013
HIGH PRESSURE WILL GRADUALLY BUILD FROM HUDSON BAY INTO NORTHERN
MICHIGAN THROUGH THE WEEKEND. THIS WEATHER PATTERN PROVIDE PLENTY OF
SUNSHINE AND WARM TEMPERATURES EACH DAY...WHILE ALSO DELIVERING
CLEAR AND CHILLY NIGHTS. OUR NEXT CHANCE FOR RAIN WILL WAIT UNTIL
EARLY NEXT WEEK...AS LOW PRESSURE TAKES SHAPE ACROSS THE WESTERN
LAKES.
&&
.UPDATE...
ISSUED AT 119 PM EDT THU MAY 16 2013
NO SIGNIFICANT CHANGES WARRANTED TO AFTERNOON FORECAST. CLOUD
COVER FAILING TO MATERIALIZE ACROSS EASTERN UPPER AS DRY AIR WINS
OUT. ELSEWHERE...CHANGES RELEGATED TO SLIGHT REAL-TIME
ADJUSTMENTS TO TEMPERATURE CURVE. ISOLATED LOCATIONS APPROACHING
RED FLAG CONDITIONS...BUT NOT WIDESPREAD ENOUGH TO WARRANT A HEADLINE.
UPDATE ISSUED AT 951 AM EDT THU MAY 16 2013
ANOTHER QUIET MORNING ACROSS THE NORTH WOODS...ALTHOUGH NOT WITHOUT
AT LEAST A FEW FORECAST CHALLENGES. BAND OF ACCAS ALONG CORRIDOR OF
IMPRESSIVE H8-H7 LAPSE RATES CONTINUES TO SPILL INTO FAR SOUTHWEST
SECTIONS OF THE AREA...AND SHOULD CONTINUE TO DO SO FOR THE NEXT
COUPLE HOURS. MUCH FURTHER NORTH...EXTENSIVE AREA OF STRATUS
CONTINUES TO SAG SOUTH AROUND BACKSIDE OF QUEBEC CENTERED LOW
PRESSURE. DIURNAL TRENDS AND DOWNSLOPING STARTING TO TAKE ITS
TOLL...WITH NOTABLE THINNING ALONG ITS SOUTHERN FLANK. STILL APPEARS
SOME OF THIS MAY SNEAK INTO EASTERN UPPER MICHIGAN...WITH ADDED
MOISTURE PERHAPS ENTICING A DIURNALLY DRIVEN STRATO-CU RESPONSE.
OTHERWISE...A DRY AND MOSTLY SUNNY DAY IS EXPECTED ACROSS THE AREA.
ONTO FIRE WEATHER CONCERNS: SECONDARY WEAK COLD FRONT HAS EXITED
SOUTH OF THE AREA...WHICH SHOULD ALLOW AFTERNOON HIGHS TO FALL JUST
SHORT OF RED FLAG CRITERIA (ESSENTIALLY...A FEW DEGREES COOLER THAN
THOSE OBSERVED YESTERDAY). WINDS AND RH VALUES...HOWEVER...EXPECTED
TO MAKE A RUN AT CRITICAL LEVELS. CORE OF GUSTY NORTHWEST WINDS (15
TO 25 MPH) EXPECTED ACROSS NORTHEAST LOWER...ESPECIALLY THROUGH
EARLY AFTERNOON. REGIONAL 12Z SOUNDING ANALYSIS AND BACKWARD
TRAJECTORY RAP GUIDANCE BOTH SUPPORT DEWPOINTS MIXING OUT INTO THE
LOWER 30S (ISOLATED UPPER 20S) THROUGH THIS AFTERNOON...PRODUCING RH
READINGS WELL BELOW 30 PERCENT ACROSS A GOOD PORTION OF INTERIOR
NORTHERN LOWER MICHIGAN. WHILE A ROGUE REG FLAG OBSERVATION OR TWO
MORE THAN EXPECTED...ESPECIALLY ACROSS THE HURON NATION FOREST
AREA...THESE SHOULD BE MORE THAN EXCEPTION THAN THE RULE...AND NOT
WORTHY OF ANY SPECIFIC HEADLINE. WILL CONTINUE TO MONITOR.
UPDATE ISSUED AT 618 AM EDT THU MAY 16 2013
NARROW LINE OF MID CLOUD PRESSING INTO NRN LOWER MICHIGAN...BUT
HAS BEEN THINNING OUT CONSIDERABLY AND NOT LIKELY TO HAVE MUCH OF
AN IMPACT ON SKY COVER THIS MORNING. TO THE NORTH...STRATUS
SLOWLY SAGGING SOUTHWARD INTO LAKE SUPERIOR WITH SHALLOW COLD
ADVECTION BEHIND THE WEAK FRONT THAT IS DROPPING THROUGH THE
REGION. NOT ENTIRELY CLEAR JUST HOW MUCH OF THE STRATUS WILL GET
INTO THE U.P. AND SUSPECT A GOOD PART WILL MIX OUT WITH DAYTIME
HEATING. BUT HAVE NUDGED UP SKY COVER (PARTLY SUNNY) FOR EASTERN
UPPER MICHIGAN LATER TODAY ACCORDINGLY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 353 AM EDT THU MAY 16 2013
OVERVIEW: FAIRLY PROGRESSIVE FLOW PATTERN ACROSS THE CONUS WITH LOW
AMPLITUDE TROUGHINESS IN THE EASTERN GREAT LAKES INTO NEW ENGLAND
AND LOW AMPLITUDE RIDGING ADVANCING THROUGH THE PLAINS. PATTERN
EXPECTED TO AMPLIFY OVER THE NEXT SEVERAL DAYS WITH RIDGING BUILDING
THROUGH THE MIDWEST AND GREAT LAKES HEADING INTO THE WEEKEND...
SIGNALING WARMER AND RAIN-FREE DAYS AHEAD.
ON THE SMALLER SCALE...LOW PRESSURE SYSTEM IS LOCATED OVER WESTERN
QUEBEC WITH A SUBTLE FRONT CURVING BACK ACROSS THE NRN LAKES/SRN
ONTARIO REGION. FRONT IS FORECAST SAG DOWN INTO LOWER MICHIGAN TODAY
RESULTING IN SUBTLE COOLING. SO TAKE YESTERDAYS HIGHS AND TRIM OFF A
FEW DEGREES...THAT SHOULD YIELD A DECENT RESULT. NO SENSIBLE WEATHER
OCCURRING OR EXPECTED TO OCCUR WITH THE FRONT ALTHOUGH THERE IS ONE
BATCH OF MID CLOUD AND SPOTTY ELEVATED RADAR RETURNS ACROSS NRN
WISCONSIN ASSOCIATED WITH POCKET OF STEEP LOW-MID LEVEL LAPSE RATES
THAT WILL SLIDE INTO LOWER MICHIGAN TODAY. IN ADDITION...CLOUD COVER
ACROSS ONTARIO BEHIND THE FRONT MAY MAKE A RUN TOWARD EASTERN UPPER
MICHIGAN BEYOND THE FRONT THIS AFTERNOON. OVERALL...EXPECT PARTLY
CLOUDY TO MOSTLY SUNNY SKIES.
FIRE WEATHER CONCERNS...DRY ANTECEDENT CONDITIONS ALREADY IN PLACE
AND FORECAST SOUNDINGS ONCE AGAIN SUGGEST THE POTENTIAL FOR SFC
DEWPOINTS TO DROP OFF THIS AFTERNOON AFTER HEATING/MIXING TAPS VERY
DRY AIR ALOFT. LOW 30S DEWPOINTS PROBABLY EASILY ATTAINABLE...WITH
EVEN LOW VALUES POSSIBLE IF WE MIX DEEP ENOUGH. THIS WILL RESULT IN
MIN AFTERNOON RH VALUES ACROSS INLAND NRN LOWER MICHIGAN DIPPING
BELOW 25 PERCENT. HOWEVER...TEMPS WILL LARGELY REMAIN BELOW RED FLAG
CRITERIA AND WINDS TODAY WILL NOT BE NEARLY AS GUSTY AS WEDNESDAY.
NO HEADLINES...BUT WILL CONTINUE TO MENTION AN ELEVATED FIRE DANGER
THIS AFTERNOON/EVENING IN TH HAZARDOUS WEATHER OUTLOOK.
TONIGHT...MAINLY CLEAR SKIES/LIGHTER WINDS AND LOW DEWPOINTS WILL
ALLOW TEMPS TO DROP INTO THE 30S FOR MOST AREAS...WITH SOME FROST A
POSSIBILITY AS WELL. DONT EXPECT WIDESPREAD FREEZING CONDITIONS...
BUT DAY SHIFT MAY NEED TO CONSIDER FROST ADVISORY POSSIBILITIES.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 353 AM EDT THU MAY 16 2013
QUIET AND DOWNRIGHT SPECTACULAR LATE SPRING WEATHER REMAINS ON TAP
AS WE WRAP UP THE WORK WEEK AND HEAD THROUGH THE WEEKEND...WITH
REALLY NO MAJOR CONCERNS FORESEEN THROUGH SUNDAY. WHAT HAPPENS
THEREAFTER IS A BIT MORE IN QUESTION...BUT SIGNS CONTINUE TO POINT
TOWARD INCREASING PRECIPITATION CHANCES SOMETIME DURING THE FIRST
HALF OF NEXT WEEK. THE WEATHER PATTERN THROUGH THE WEEKEND IS A
QUIET ONE FOR NORTHERN MICHIGAN...FEATURING A TRANSITION FROM A
RATHER FLAT FLOW ACROSS THE NORTHERN TIER...TOWARD ONE OF AMPLIFIED
UPPER RIDGING BUILDING ACROSS THE WESTERN LAKES BY SUNDAY...
DOWNSTREAM OF RATHER SHARP TROUGH AMPLIFICATION TAKING SHAPE OVER
THE ROCKIES AND EVENTUALLY PLAINS/MISSISSIPPI VALLEY EARLY NEXT
WEEK. SAID PATTERN WILL ALSO FORCE A RATHER PRONOUNCED AREA OF MID
LEVEL CONFLUENCE ACROSS MUCH OF EASTERN CANADA WITH TIME...HELPING
DRIVE LOW LEVEL RIDGING FROM HUDSON BAY THIS WEEKEND INTO SOUTHERN
NEWFOUNDLAND BY EARLY NEXT WEEK.
LOOKING AT A FEW SPECIFICS...JUST NOT TERRIBLY EXCITED BY ANY PRECIP
CHANCES THROUGH THE WEEKEND...AS LOW LEVEL RIDGING DOMINATES WHILE
MID LEVEL HEIGHTS GRADUALLY BUILD WITH TIME. ANY MAJOR PRECIP THREAT
SHOULD BE CONFINED ACROSS THE OHIO AND MID MISSISSIPPI VALLEYS ALONG
A STALLED FRONTAL BOUNDARY (NEAR ITS CLIMO-FAVORED LOCATION THIS
TIME OF YEAR). JUST NOT BUYING INTO NAM/GFS DEPICTION OF ELEVATED
CONVECTION FIRING THIS FAR NORTH LATER FRIDAY NIGHT INTO SATURDAY...
AS THIS APPEARS TO BE TIED TO ERRONEOUS MOISTURE TRANSPORT NORTHWARD
(THIS IS A BIG PROBLEM SO FAR THIS YEAR). IN ADDITION...THE BEST
LOWER LEVEL CONVERGENCE LOOKS TO RESIDE WELL NORTHWEST OF THE AREA
ALONG AN ELEVATED WARM FRONT THROUGH WESTERN ONTARIO...WHILE A
PRONOUNCED SUB-800MB DRY WEDGE DOMINATES NORTHERN MICHIGAN. AS
SUCH...REALLY LIKE OUR CALL TO GO DRY AND WILL MAINTAIN...WITH
PERHAPS JUST A LITTLE INCREASE IN SOME MID OR HIGH CLOUDS EXPECTED.
HIGHS SHOULD WARM WELL INTO THE 60S AND 70S ONCE AGAIN...COOLEST
NEAR THE LAKESHORES WHERE LAKE BREEZE DEVELOPMENT IS LIKELY IN A
WEAK GRADIENT REGIME...ESPECIALLY FRIDAY AND SATURDAY. NIGHTS
CONTINUE TO LOOK COOL AND QUITE COMFORTABLE...AND GIVEN THE SETUP
WITH RESPECTABLE MIXING OUT OF DEW POINTS EACH AFTERNOON AND WEAK
WIND FIELDS...WILL UNDERCUT GUIDANCE NUMBERS...ESPECIALLY FRIDAY
NIGHT WITH SOME LOWER 30S POSSIBLE FOR THE USUAL COOL SPOTS ONCE
AGAIN.
THEREAFTER...CONFIDENCE CONTINUES TO BE ON THE LOW SIDE EARLY NEXT
WEEK REGARDING THE EVOLUTION OF PRECIP CHANCES ACROSS THE AREA.
LATEST GUIDANCE STILL SUGGESTING GRADUAL CLOSED LOW DEVELOPMENT OFF
TO OUR WEST ACROSS THE CENTRAL OR NORTHERN PLAINS. WHILE THE OVERALL
SPECIFICS AREN`T KNOWN JUST YET...PRECIP CHANCES WILL BE ON THE
INCREASE AS AN ELEVATED WARM FRONT EVENTUALLY WORKS NORTH THROUGH
THE AREA...FOLLOWED BY A SURFACE WARM FRONT...ALL WHILE INCREASING
DIFLUENCE ALOFT WORKS IN TANDEM WITH STRENGTHENING RETURN FLOW WITH
A WIDE OPEN GULF. IN FACT...SHOULD THINGS SET UP AS CURRENT MODELED
(THEY RARELY DO)...COULD SEE THIS BEING A HEAVY RAIN SETUP SOMEWHERE
NEARBY. OTHERWISE...TEMPS ARE QUITE TRICKY IN THIS SETUP...WITH THE
POTENTIAL FOR SOME SNEAKY VERY WARM READINGS (WELL INTO THE 80S?) AS
PRONOUNCED THERMAL RIDGING RIDES NORTH INTO THE AREA...BUT ALSO THE
CHANCE FOR RAIN-COOLED 60S PENDING THE EXACT EVOLUTION OF ANY
PRECIP. WILL CONTINUE TO SPLIT THE DIFFERENCE AT THIS POINT...BUT
WITH A NOTABLE TREND TOWARD MUCH MORE HUMID CONDITIONS TOWARD
TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 119 PM EDT THU MAY 16 2013
VFR CONDITIONS THROUGH THIS FORECAST. GUSTY NORTHWEST WINDS
QUICKLY SUBSIDE THIS EVENING...WITH LIGHT EAST FLOW EXPECTED TO
DEVELOP FRIDAY MORNING. CLEAR SKIES GIVE WAY TO INCREASING
HIGH/MID LEVEL CLOUDS LATE TONIGHT AND FRIDAY...WITH NO PRECIP
EXPECTED.
&&
.MARINE...
ISSUED AT 353 AM EDT THU MAY 16 2013
NORTHWEST WINDS WILL PREVAIL TODAY WITH SOME GUSTINESS...ALTHOUGH
GUSTS AND WAVES ARE EXPECTED TO REMAIN LARGELY BELOW SMALL CRAFT
CRITERIA. WINDS GO LIGHT TONIGHT AND REMAIN LIGHT THROUGH FRIDAY
NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...DL
SHORT TERM...BA
LONG TERM...DL
AVIATION...MB
MARINE...BA
AREA FORECAST DISCUSSION
NWS GAYLORD MI
951 AM EDT THU MAY 16 2013
.SYNOPSIS...
ISSUED AT 353 AM EDT THU MAY 16 2013
HIGH PRESSURE WILL GRADUALLY BUILD FROM HUDSON BAY INTO NORTHERN
MICHIGAN THROUGH THE WEEKEND. THIS WEATHER PATTERN PROVIDE PLENTY OF
SUNSHINE AND WARM TEMPERATURES EACH DAY...WHILE ALSO DELIVERING
CLEAR AND CHILLY NIGHTS. OUR NEXT CHANCE FOR RAIN WILL WAIT UNTIL
EARLY NEXT WEEK...AS LOW PRESSURE TAKES SHAPE ACROSS THE WESTERN
LAKES.
&&
.UPDATE...
ISSUED AT 951 AM EDT THU MAY 16 2013
ANOTHER QUIET MORNING ACROSS THE NORTH WOODS...ALTHOUGH NOT WITHOUT
AT LEAST A FEW FORECAST CHALLENGES. BAND OF ACCAS ALONG CORRIDOR OF
IMPRESSIVE H8-H7 LAPSE RATES CONTINUES TO SPILL INTO FAR SOUTHWEST
SECTIONS OF THE AREA...AND SHOULD CONTINUE TO DO SO FOR THE NEXT
COUPLE HOURS. MUCH FURTHER NORTH...EXTENSIVE AREA OF STRATUS
CONTINUES TO SAG SOUTH AROUND BACKSIDE OF QUEBEC CENTERED LOW
PRESSURE. DIURNAL TRENDS AND DOWNSLOPING STARTING TO TAKE ITS
TOLL...WITH NOTABLE THINNING ALONG ITS SOUTHERN FLANK. STILL APPEARS
SOME OF THIS MAY SNEAK INTO EASTERN UPPER MICHIGAN...WITH ADDED
MOISTURE PERHAPS ENTICING A DIURNALLY DRIVEN STRATO-CU RESPONSE.
OTHERWISE...A DRY AND MOSTLY SUNNY DAY IS EXPECTED ACROSS THE AREA.
ONTO FIRE WEATHER CONCERNS: SECONDARY WEAK COLD FRONT HAS EXITED
SOUTH OF THE AREA...WHICH SHOULD ALLOW AFTERNOON HIGHS TO FALL JUST
SHORT OF RED FLAG CRITERIA (ESSENTIALLY...A FEW DEGREES COOLER THAN
THOSE OBSERVED YESTERDAY). WINDS AND RH VALUES...HOWEVER...EXPECTED
TO MAKE A RUN AT CRITICAL LEVELS. CORE OF GUSTY NORTHWEST WINDS (15
TO 25 MPH) EXPECTED ACROSS NORTHEAST LOWER...ESPECIALLY THROUGH
EARLY AFTERNOON. REGIONAL 12Z SOUNDING ANALYSIS AND BACKWARD
TRAJECTORY RAP GUIDANCE BOTH SUPPORT DEWPOINTS MIXING OUT INTO THE
LOWER 30S (ISOLATED UPPER 20S) THROUGH THIS AFTERNOON...PRODUCING RH
READINGS WELL BELOW 30 PERCENT ACROSS A GOOD PORTION OF INTERIOR
NORTHERN LOWER MICHIGAN. WHILE A ROGUE REG FLAG OBSERVATION OR TWO
MORE THAN EXPECTED...ESPECIALLY ACROSS THE HURON NATION FOREST
AREA...THESE SHOULD BE MORE THAN EXCEPTION THAN THE RULE...AND NOT
WORTHY OF ANY SPECIFIC HEADLINE. WILL CONTINUE TO MONITOR.
UPDATE ISSUED AT 618 AM EDT THU MAY 16 2013
NARROW LINE OF MID CLOUD PRESSING INTO NRN LOWER MICHIGAN...BUT
HAS BEEN THINNING OUT CONSIDERABLY AND NOT LIKELY TO HAVE MUCH OF
AN IMPACT ON SKY COVER THIS MORNING. TO THE NORTH...STRATUS
SLOWLY SAGGING SOUTHWARD INTO LAKE SUPERIOR WITH SHALLOW COLD
ADVECTION BEHIND THE WEAK FRONT THAT IS DROPPING THROUGH THE
REGION. NOT ENTIRELY CLEAR JUST HOW MUCH OF THE STRATUS WILL GET
INTO THE U.P. AND SUSPECT A GOOD PART WILL MIX OUT WITH DAYTIME
HEATING. BUT HAVE NUDGED UP SKY COVER (PARTLY SUNNY) FOR EASTERN
UPPER MICHIGAN LATER TODAY ACCORDINGLY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 353 AM EDT THU MAY 16 2013
OVERVIEW: FAIRLY PROGRESSIVE FLOW PATTERN ACROSS THE CONUS WITH LOW
AMPLITUDE TROUGHINESS IN THE EASTERN GREAT LAKES INTO NEW ENGLAND
AND LOW AMPLITUDE RIDGING ADVANCING THROUGH THE PLAINS. PATTERN
EXPECTED TO AMPLIFY OVER THE NEXT SEVERAL DAYS WITH RIDGING BUILDING
THROUGH THE MIDWEST AND GREAT LAKES HEADING INTO THE WEEKEND...
SIGNALING WARMER AND RAIN-FREE DAYS AHEAD.
ON THE SMALLER SCALE...LOW PRESSURE SYSTEM IS LOCATED OVER WESTERN
QUEBEC WITH A SUBTLE FRONT CURVING BACK ACROSS THE NRN LAKES/SRN
ONTARIO REGION. FRONT IS FORECAST SAG DOWN INTO LOWER MICHIGAN TODAY
RESULTING IN SUBTLE COOLING. SO TAKE YESTERDAYS HIGHS AND TRIM OFF A
FEW DEGREES...THAT SHOULD YIELD A DECENT RESULT. NO SENSIBLE WEATHER
OCCURRING OR EXPECTED TO OCCUR WITH THE FRONT ALTHOUGH THERE IS ONE
BATCH OF MID CLOUD AND SPOTTY ELEVATED RADAR RETURNS ACROSS NRN
WISCONSIN ASSOCIATED WITH POCKET OF STEEP LOW-MID LEVEL LAPSE RATES
THAT WILL SLIDE INTO LOWER MICHIGAN TODAY. IN ADDITION...CLOUD COVER
ACROSS ONTARIO BEHIND THE FRONT MAY MAKE A RUN TOWARD EASTERN UPPER
MICHIGAN BEYOND THE FRONT THIS AFTERNOON. OVERALL...EXPECT PARTLY
CLOUDY TO MOSTLY SUNNY SKIES.
FIRE WEATHER CONCERNS...DRY ANTECEDENT CONDITIONS ALREADY IN PLACE
AND FORECAST SOUNDINGS ONCE AGAIN SUGGEST THE POTENTIAL FOR SFC
DEWPOINTS TO DROP OFF THIS AFTERNOON AFTER HEATING/MIXING TAPS VERY
DRY AIR ALOFT. LOW 30S DEWPOINTS PROBABLY EASILY ATTAINABLE...WITH
EVEN LOW VALUES POSSIBLE IF WE MIX DEEP ENOUGH. THIS WILL RESULT IN
MIN AFTERNOON RH VALUES ACROSS INLAND NRN LOWER MICHIGAN DIPPING
BELOW 25 PERCENT. HOWEVER...TEMPS WILL LARGELY REMAIN BELOW RED FLAG
CRITERIA AND WINDS TODAY WILL NOT BE NEARLY AS GUSTY AS WEDNESDAY.
NO HEADLINES...BUT WILL CONTINUE TO MENTION AN ELEVATED FIRE DANGER
THIS AFTERNOON/EVENING IN TH HAZARDOUS WEATHER OUTLOOK.
TONIGHT...MAINLY CLEAR SKIES/LIGHTER WINDS AND LOW DEWPOINTS WILL
ALLOW TEMPS TO DROP INTO THE 30S FOR MOST AREAS...WITH SOME FROST A
POSSIBILITY AS WELL. DONT EXPECT WIDESPREAD FREEZING CONDITIONS...
BUT DAY SHIFT MAY NEED TO CONSIDER FROST ADVISORY POSSIBILITIES.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 353 AM EDT THU MAY 16 2013
QUIET AND DOWNRIGHT SPECTACULAR LATE SPRING WEATHER REMAINS ON TAP
AS WE WRAP UP THE WORK WEEK AND HEAD THROUGH THE WEEKEND...WITH
REALLY NO MAJOR CONCERNS FORESEEN THROUGH SUNDAY. WHAT HAPPENS
THEREAFTER IS A BIT MORE IN QUESTION...BUT SIGNS CONTINUE TO POINT
TOWARD INCREASING PRECIPITATION CHANCES SOMETIME DURING THE FIRST
HALF OF NEXT WEEK. THE WEATHER PATTERN THROUGH THE WEEKEND IS A
QUIET ONE FOR NORTHERN MICHIGAN...FEATURING A TRANSITION FROM A
RATHER FLAT FLOW ACROSS THE NORTHERN TIER...TOWARD ONE OF AMPLIFIED
UPPER RIDGING BUILDING ACROSS THE WESTERN LAKES BY SUNDAY...
DOWNSTREAM OF RATHER SHARP TROUGH AMPLIFICATION TAKING SHAPE OVER
THE ROCKIES AND EVENTUALLY PLAINS/MISSISSIPPI VALLEY EARLY NEXT
WEEK. SAID PATTERN WILL ALSO FORCE A RATHER PRONOUNCED AREA OF MID
LEVEL CONFLUENCE ACROSS MUCH OF EASTERN CANADA WITH TIME...HELPING
DRIVE LOW LEVEL RIDGING FROM HUDSON BAY THIS WEEKEND INTO SOUTHERN
NEWFOUNDLAND BY EARLY NEXT WEEK.
LOOKING AT A FEW SPECIFICS...JUST NOT TERRIBLY EXCITED BY ANY PRECIP
CHANCES THROUGH THE WEEKEND...AS LOW LEVEL RIDGING DOMINATES WHILE
MID LEVEL HEIGHTS GRADUALLY BUILD WITH TIME. ANY MAJOR PRECIP THREAT
SHOULD BE CONFINED ACROSS THE OHIO AND MID MISSISSIPPI VALLEYS ALONG
A STALLED FRONTAL BOUNDARY (NEAR ITS CLIMO-FAVORED LOCATION THIS
TIME OF YEAR). JUST NOT BUYING INTO NAM/GFS DEPICTION OF ELEVATED
CONVECTION FIRING THIS FAR NORTH LATER FRIDAY NIGHT INTO SATURDAY...
AS THIS APPEARS TO BE TIED TO ERRONEOUS MOISTURE TRANSPORT NORTHWARD
(THIS IS A BIG PROBLEM SO FAR THIS YEAR). IN ADDITION...THE BEST
LOWER LEVEL CONVERGENCE LOOKS TO RESIDE WELL NORTHWEST OF THE AREA
ALONG AN ELEVATED WARM FRONT THROUGH WESTERN ONTARIO...WHILE A
PRONOUNCED SUB-800MB DRY WEDGE DOMINATES NORTHERN MICHIGAN. AS
SUCH...REALLY LIKE OUR CALL TO GO DRY AND WILL MAINTAIN...WITH
PERHAPS JUST A LITTLE INCREASE IN SOME MID OR HIGH CLOUDS EXPECTED.
HIGHS SHOULD WARM WELL INTO THE 60S AND 70S ONCE AGAIN...COOLEST
NEAR THE LAKESHORES WHERE LAKE BREEZE DEVELOPMENT IS LIKELY IN A
WEAK GRADIENT REGIME...ESPECIALLY FRIDAY AND SATURDAY. NIGHTS
CONTINUE TO LOOK COOL AND QUITE COMFORTABLE...AND GIVEN THE SETUP
WITH RESPECTABLE MIXING OUT OF DEW POINTS EACH AFTERNOON AND WEAK
WIND FIELDS...WILL UNDERCUT GUIDANCE NUMBERS...ESPECIALLY FRIDAY
NIGHT WITH SOME LOWER 30S POSSIBLE FOR THE USUAL COOL SPOTS ONCE
AGAIN.
THEREAFTER...CONFIDENCE CONTINUES TO BE ON THE LOW SIDE EARLY NEXT
WEEK REGARDING THE EVOLUTION OF PRECIP CHANCES ACROSS THE AREA.
LATEST GUIDANCE STILL SUGGESTING GRADUAL CLOSED LOW DEVELOPMENT OFF
TO OUR WEST ACROSS THE CENTRAL OR NORTHERN PLAINS. WHILE THE OVERALL
SPECIFICS AREN`T KNOWN JUST YET...PRECIP CHANCES WILL BE ON THE
INCREASE AS AN ELEVATED WARM FRONT EVENTUALLY WORKS NORTH THROUGH
THE AREA...FOLLOWED BY A SURFACE WARM FRONT...ALL WHILE INCREASING
DIFLUENCE ALOFT WORKS IN TANDEM WITH STRENGTHENING RETURN FLOW WITH
A WIDE OPEN GULF. IN FACT...SHOULD THINGS SET UP AS CURRENT MODELED
(THEY RARELY DO)...COULD SEE THIS BEING A HEAVY RAIN SETUP SOMEWHERE
NEARBY. OTHERWISE...TEMPS ARE QUITE TRICKY IN THIS SETUP...WITH THE
POTENTIAL FOR SOME SNEAKY VERY WARM READINGS (WELL INTO THE 80S?) AS
PRONOUNCED THERMAL RIDGING RIDES NORTH INTO THE AREA...BUT ALSO THE
CHANCE FOR RAIN-COOLED 60S PENDING THE EXACT EVOLUTION OF ANY
PRECIP. WILL CONTINUE TO SPLIT THE DIFFERENCE AT THIS POINT...BUT
WITH A NOTABLE TREND TOWARD MUCH MORE HUMID CONDITIONS TOWARD
TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 618 AM EDT THU MAY 16 2013
SOLID VFR CONDITIONS ANTICIPATED THROUGH THE TAF PERIOD. WINDS
WILL VEER NORTHERLY THIS MORNING WITH SOME GUSTINESS AROUND 20
KNOTS...ESPECIALLY AT PLN AND APN. WINDS DIMINISH TONIGHT AND FOR
FRIDAY.
&&
.MARINE...
ISSUED AT 353 AM EDT THU MAY 16 2013
NORTHWEST WINDS WILL PREVAIL TODAY WITH SOME GUSTINESS...ALTHOUGH
GUSTS AND WAVES ARE EXPECTED TO REMAIN LARGELY BELOW SMALL CRAFT
CRITERIA. WINDS GO LIGHT TONIGHT AND REMAIN LIGHT THROUGH FRIDAY
NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...DL
SHORT TERM...BA
LONG TERM...DL
AVIATION...BA
MARINE...BA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
139 AM EDT THU MAY 16 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 409 PM EDT WED MAY 15 2013
WV IMAGERY AND RUC ANALYSIS INDICATED WNW MID/UPPER LEVEL FLOW
THROUGH THE NRN GREAT LAKES ON THE SRN FLANK OF A TROUGH OVER NRN
ONTARIO TO THE SRN END OF JAMES BAY. A WEAK SHORTWAVE TROUGH
OVER THE SE CORNER OF MANITOBA SUPPORTED AN AREA OF MID CLOUDS AND
SOME SCT/ISOLD -SHRA INTO NW MN. AT THE SFC...A TIGHT PRES GRADIENT
PERSISTED BTWN A 995 MB LOW BTWN JAMES BAY AND LAKE SUPERIOR AND A
RIDGE FROM THE NRN PLAINS INTO SRN MN. WNW WINDS HAVE GUSTED AT OR
ABOVE 30 MPH OVER MUCH OF UPPER MI AND TO NEAR 45 MPH WHERE TERRAIN
HAS BOOSTED THE WINDS AT CMX. SUNSHINE WITH TEMPS INTO THE LOWER TO
MID 70S AND DEEP MIXING TO AROUND 750 MB HAS LOWERED DEWPOINTS TO
AROUND 30F WITH RH VALUES TO AROUND 20 PCT. THE COMBINATION OF THE
DRY AIR WINDS HAS RESULTED IN CRITICAL FIRE WEATHER CONDITIONS.
TONIGHT...AS THE PRES GRADIENT WEAKENS AND DAYTIME HEATING
SUBSIDES...WINDS WILL DIMINISH QUICKLY THIS EVENING AND BECOME LIGHT
OVERNIGHT. HIGHER RES SHORT RANGE MODELS SUGGEST THAT THE BEST
CHANCES OF PCPN ASSOCIATED WITH THE MANITOBA SHORTWAVE OVER THE SW
HALF OF UPPER MI. EVEN THERE...WITH DRY LOW LEVELS AND WEAK FORCING
WITH THE SHRTWV MAINLY JUST SPRINKLES AT MOST WOULD BE EXPECTED.
SO...ONLY A SMALL AREA OF SLIGHT CHANCE POPS WERE INCLUDED.
THURSDAY...EXPECT COOLER CONDITIONS OVER THE NORTH HALF OF UPPER MI
WITH NRLY WINDS BEHIND A COLD FRONT MOVING THROUGH THE AREA LATE
TONIGHT. WITH 850 MB TEMPS RANGING FROM AROUND 4C NORTH TO TO 9C
SOUTH...TEMPS SHOULD RANGE FROM THE LOWER 50S NEAR LAKE SUPERIOR TO
THE LOWER 70S INLAND SOUTHWEST. SUNSHINE AND FAVORABLE MIXING WILL
AGAIN DROP DEWPOINTS INTO THE LOWER 30S WITH RH VALUES TO AROUND 25
PERCENT SOUTH. HOWEVER...WITH WINDS ONLY TO AROUND 10 MPH...THE
WILDFIRE RISK WILL BE LOWER THAN TODAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 440 PM EDT WED MAY 15 2013
TEMPS WILL HOLD STEADY IN THE 60S ON FRIDAY AND SATURDAY...WITH A
WARM UP FOR SUNDAY AS SSE WINDS INCREASE AHEAD OF LOW PRESSURE
NEARING FROM THE CENTRAL PLAINS. AT THIS POINT THE STRONGER WINDS
LOOK TO BE ASSOCIATED WITH INCREASED DEW POINTS...LIMITING
SIGNIFICANT FIRE CONCERNS.
THERE IS A LOT OF UNCERTAINTY WITH THE MID TO LONGER RANGE OF THIS
FORECAST...WITH THE TRACK AND TIMING OF THE SLOW MOVING LOW PRESSURE
SYSTEM. WITH THAT SAID...THERE IS A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST FROM SATURDAY ON /MAINLY WEST/.
THUNDERSTORM CHANCES ARE NOT THAT IMPRESSIVE. IT LOOKS LIKE THE BEST
CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE ENTIRE CWA WILL HOLD
OFF UNTIL MONDAY...WITH THE SFC LOW IS SET UP OVER THE EASTERN
DAKOTAS AND WESTERN MN. THE SYSTEM CONTINUES TO SLOW DOWN...AS IT
WAS ORIGINALLY EXPECTED TO CROSS UPPER MI ON SUNDAY...AT LEAST OF A
COUPLE OF DAYS AGO. NOW IT LOOKS TO HOLD OFF UNTIL TUESDAY AT THE
EARLIEST /12Z ECMWF SOLUTION/. THE GFS IS EVEN SLOWER...AND HAS THE
500MB LOW OVER ND TUESDAY AFTERNOON RETROGRADING AND CONSOLIDATING
WITH THE DEEP LOW PUSHING INTO THE PACIFIC NORTHWEST. WILL OPT FOR
FOR A SOLUTION CLOSER TO THE ECMWF AT THIS POINT...WITH LOWER
CONFIDENCE IN THE FORECAST BEYOND SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 137 AM EDT THU MAY 16 2013
EXPECT VFR CONDITIONS/LIGHT N-E WINDS THIS TAF PERIOD WITH DRY HI
PRES DOMINATING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT WED MAY 15 2013
EXPECT WINDS WITH GUSTS 25 KNOTS TO DIMINISH TONIGHT AS HIGH PRES
BUILDS INTO THE REGION. HIGH PRESSURE WILL EXPAND ACROSS GREAT LAKES
INTO THE WEEKEND WITH EAST-SOUTHEAST WINDS AT OR BLO 25 KTS. WINDS
BECOME SOUTHERLY LATE THIS WEEKEND AHEAD OF LOW PRESSURE TROUGH
PUSHING IN FROM NORTHERN PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1230 AM CDT THU MAY 16 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 348 PM CDT WED MAY 15 2013
FORECAST COULD BE PRETTY COMPLICATED CONCERNING CHANCES OF
PRECIPITATION FOR THE SHORT TERM.
FOR STARTERS...A NEARLY STATIONARY BOUNDARY IN OUR FAR SOUTHERN CWA
COULD BE THE FOCUS OF SOME AFTERNOON AND EVENING THUNDERSTORM
ACTIVITY. SHEAR IS EXTREMELY WEAK AND INSTABILITY IS MARGINAL AT
BEST. WE STILL HAVE INVERTED V SOUNDINGS...BUT NOT MIXING NEARLY AS
HIGH AS YESTERDAY...AND AIR NOT NEARLY AS DRY. OUR MAIN CONCERN
WOULD BE TO GET AN ISOLATED STRONG TO SEVERE WIND GUST...BUT THIS
WOULD BE A LONGSHOT. WENT CLOSER WITH RAP FOR DEWPOINTS AND WIND
WITHIN THE FIRST 6 TO 12 HOURS AS THE SOLUTIONS OF THIS MODEL HAVE
BEEN SUPERIOR TO OTHERS. I HAD TO INCREASE THE TOP END OF WIND
SPEEDS A BIT AS WE ARE MIXING A BIT BETTER THAN WHAT IS
FORECAST...BUT AS THE FRONT EDGES NORTH...WIND SPEEDS SHOULD
DECREASE ACROSS MUCH OF THE CWA. WENT TOWARD CONSRAW FOR DEWPOINTS
AS WE GET CLOSER TO THE OVERNIGHT HOURS INTO THURSDAY. THERE IS A
BIT OF A SIGNAL FOR SOME FOG TONIGHT FROM THE SREF SO WILL
CONTINUE WITH MENTIONING OF PATCHY FOG...ESPECIALLY AS THE FRONT
MOVES NORTH.
THE FORECAST GETS A LITTLE MUDDLED TONIGHT FOR PRECIPITATION
CHANCES. MODELS ARE GENERALLY LIFTING THE BOUNDARY TO THE NORTH AS A
WARM FRONT. THERE WILL NOT BE MUCH OF A LOW-LEVEL JET TO SUSTAIN ANY
CONVECTION THAT MIGHT FIRE UP THIS AFTERNOON AND EVENING. WITH
DECREASING WITH SUNSET...MOST CONVECTION SHOULD DIE OUT.
OVERNIGHT...HOWEVER...SOME MODELS ARE INDICATING THE POSSIBILITY OF
MORE CONVECTION MAINLY IN THE NORTHERN CWA. THE NMM INDICATES A
POSSIBLE SMALL-SCALE MCS DEVELOP OVER THE CWA OF LBF AND FOLLOW THE
BOUNDARY TO THE EAST ACROSS THE NORTHERN CWA...WHICH MAY POSSIBLY
LAST INTO THE EARLY MORNING HOURS.
THEN ANOTHER LULL IS LIKELY BY LATE MORNING THURSDAY INTO EARLY
AFTERNOON AS THE BOUNDARY TO THE NORTH EITHER CONTINUES TO LIFT
NORTH OR WASHES OUT...DEPENDING ON WHICH SOLUTION IS REALIZED.
EITHER WAY...A LULL IS LIKELY. A MID-LEVEL PERTURBATION IS STILL
FORECAST TO MOVE EAST ACROSS THE AREA BY THURSDAY AFTERNOON...BUT
AMPLITUDE SHOULD REMAIN QUITE LOW. AS A THETA E RIDGE SHIFTS
EAST...ALONG WITH THE WEAK PERTURBATION...WE SHOULD HAVE A GOOD SHOT
OF SOME SHOWERS AND THUNDERSHOWERS...ESPECIALLY WEST/INTO CENTRAL
PARTS OF THE CWA. MUCAPES WILL BE HIGH ENOUGH TO SUSTAIN
THUNDERSTORMS...BUT SHEAR WILL BE WEAK ONCE AGAIN...SO SEVERE
WEATHER WOULD NOT BE OUT OF THE QUESTION...BUT CERTAINLY NO OUTBREAK
IS ANTICIPATED.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 348 PM CDT WED MAY 15 2013
FOCUS OF THE LONG TERM PERIOD WILL CENTER AROUND CHANCES FOR
THUNDERSTORMS...SOME OF WHICH MIGHT BE POSSIBLY SEVERE AT
TIMES...MAINLY SATURDAY AFTERNOON THROUGH SUNDAY EVENING.
THE CUTOFF LOW ACROSS THE DESERT SOUTHWEST WILL FINALLY BEGIN TO
INGEST BACK INTO THE MEAN FLOW THROUGHOUT THE SHORT TERM...FINALLY
SHIFTING OFF TO THE SOUTHEAST ACROSS MISSOURI AND ARKANSAS BY
THURSDAY NIGHT. THROUGH THE OVERNIGHT PERIODS...A WEAK UPPER LEVEL
DISTURBANCE WILL BEGIN TO SHIFT ACROSS THE PLAINS...ON THE BACKSIDE
OF THE UPPER LEVEL LOW. MODELS DISAGREE ON THE DEPTH OF THE
WAVE...WITH THE ECMWF...UKMET AND NAM SOLUTIONS A BIT MORE SHALLOW
THAN THE DEEPER PROGRESSIVE GFS. AT THE SURFACE...MODELS INDICATE A
A DEVELOPING TROUGH ALONG THE FRONT RANGE OF THE ROCKIES...WITH SOME
SORT OF FRONT...WASHED OUT BOUNDARY SHIFTING NORTH OF THE OUTLOOK
AREA. COMBINED WITH THE WAVE AND WARM AIR ADVECTION...MODELS
CONTINUE TO HINT AT AT LEAST A CHANCE FOR PRECIPITATION...WITH THE
GFS HEDGING FURTHER SOUTH INTO KANSAS. AT THIS POINT...REALLY NOT
BUYING INTO THE SOUTHERN SOLUTION AND TRENDING MORE TOWARDS A
NEBRASKA RAIN EVENT.
AFTER THE PASSAGE OF THE UPPER LEVEL WAVE...SUBSIDENCE TAKES
HOLD...AND CURRENT THINKING IS THAT MUCH OF FRIDAY DURING THE DAY
WILL BE DRY. HOWEVER...BY FRIDAY AFTERNOON AND EVENING...ANOTHER
UPPER LEVEL TROUGH WILL BEGIN TO SHIFT INTO THE AREA. WITH THE
EASTWARD PROGRESSION OF THE TROUGH...HEIGHT FALLS...AND A SURFACE
LEESIDE TROUGH...ITS POSSIBLE WESTERN PORTIONS OF NEBRASKA COULD SEE
SOME CONVECTION FRIDAY AFTERNOON. A FAIRLY DECENT LLJ IS EXPECTED TO
DEVELOP ACROSS WESTERN AREAS AND SHIFT EASTWARD OVERNIGHT. THIS
COMBINED WITH A DECENT THETA E RIDGE OVER THE OUTLOOK AREA...WENT
AHEAD AND CONTINUED AT LEAST SLIGHT POPS OVERNIGHT. SHOULD STORMS
DEVELOP...THERE IS PLENTY OF INSTABILITY TO WORK WITH...ABOUT
2000-3000 J/KG. HOWEVER...A STRONG CAP EXISTS WITH 700 MB
TEMPERATURES NEAR 10 TO 11 DEGREES...AND BULK SHEAR IS LIMITED
AROUND 20 TO 30 KTS.
SATURDAY LOOKS TO BE THE MAIN FOCUS OF THE MID TERM PERIOD...AS THE
UPPER LEVEL LOW SHIFTS EASTWARD. BY SATURDAY AFTERNOON...THE SURFACE
TROUGH BECOMES ELONGATED ALONG THE FRONT RANGE. BOTH THE GFS AND
ECMWF SOLUTIONS HAVE BEGUN TO TREND A BIT SLOWER IN PREVIOUS
RUNS...BRINGING IN CHANCES FOR PRECIPITATION ACROSS THE
WEST...MAINLY DURING LATE AFTERNOON AND EVENING. INSTABILITY IS
QUITE HIGH DURING THE SATURDAY AFTERNOON PERIOD THROUGH
OVERNIGHT...WITH 4000 TO 5000 J/KG POSSIBLE. AGAIN...AS HAS BEEN THE
CASE MOST OF THIS WEEK...700 MB TEMPERATURES ARE ON THE ORDER OF 10
TO 12 AND EVEN 13 DEGREES AT TIMES. 0 TO 6 KM BULK SHEAR IS ALSO AT
ITS HIGHEST SATURDAY EVENING...CLIMBING TO NEAR 30 TO 40 KTS...WITH
50 KTS EXPECTED FURTHER WEST.
BY SUNDAY AFTERNOON...THE SURFACE TROUGH AND FRONTAL BOUNDARY WILL
FINALLY MIGRATE EASTWARD ACROSS THE CWA. THIS WILL GIVE US YET
ANOTHER CHANCE FOR PRECIPITATION...POSSIBLY SEVERE AS THE CWA
REMAINS SITUATED JUST ON THE EASTERN FRINGE OF THE UPPER LEVEL
TROUGH. THE ECMWF SOLUTIONS TENDS TO BE A BIT MORE PROGRESSIVE THAN
THE GFS SOLUTION WITH A CLOSED LOW ACROSS NORTHERN NEBRASKA BY 0Z
MONDAY...WHILE THE GFS REMAINS CLOSED OVER THE PANHANDLE. SEVERE IS
BEGINNING TO LOOK POSSIBLE ALSO ON SUNDAY. INSTABILITY DOES NOT LOOK
QUITE AS STRONG AS SATURDAY BUT STILL IS NEAR 2000 J/KG OF MOST
UNSTABLE CAPE. HOWEVER...THE CAP IS ALSO NOT QUITE AS STRONG WITH
700 MB TEMPERATURES ON THE ORDER OF 6 TO 7 DEGREES CELSIUS.
THEREFORE...SEVERE STORMS DO NOT LOOK OUT OF THE QUESTION FOR SUNDAY
AFTERNOON.
THROUGH THE REST OF THE LONG TERM...THE UPPER LEVEL LOW SPINS ACROSS
THE PLAINS GENERATING CHANCES FOR PRECIPITATION THROUGH MONDAY.
HOWEVER...AN UPPER LEVEL RIDGE LOOKS TO SLOWLY BEGIN TO BUILD ACROSS
THE DESERT SOUTHWEST TOWARDS THE BEGINNING OF NEXT WEEK. AS
SUCH...THE UPPER LEVEL LOW EJECTS NORTHWARD...WITH PRECIPITATION
QUICKLY EXITING THE REGION. DECIDED TO PULL OUT ANY SLIGHT MENTION
OF PRECIPITATION ALONG THE FRINGES OF THE CWA AS THE CWA SEEMS TO
BECOME DRY SLOTTED BY MONDAY NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1230 AM CDT THU MAY 16 2013
VFR CONDITIONS ARE EXPECTED AT THE TERMINAL DURING THE VALID TAF
PERIOD. MAIN CONCERN DURING THIS TAF PERIOD IS THE CHANCE FOR
THUNDERSTORMS THURSDAY AFTERNOON. THESE STORMS SHOULD BE ISOLATED
IN NATURE AND NOT WIDESPREAD. CHANCES WILL DIMINISH AFTER
MIDNIGHT TOMORROW. THERE COULD BE SOME PATCHY FOG IN THE MORNING
AROUND THE TERMINAL...HOWEVER...CONFIDENCE IS NOT HIGH AT THE
MOMENT AND WILL NOT MENTION THIS IN THE TAF FOR NOW. CONDITIONS
WILL BE MONITORED CLOSELY AND AN AMENDMENT MAY BE ISSUED LATER
THIS EVENING...IF NEEDED.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...HEINLEIN
LONG TERM...SALTZMAN
AVIATION...GUERRERO
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
233 PM EDT THU MAY 16 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL CONTROL OUR WEATHER THROUGH SATURDAY,
BRINGING DRY CONDITIONS AND MILD DAYTIME TEMPERATURES TO NEW YORK
AND PENNSYLVANIA.
&&
.NEAR TERM /THROUGH TONIGHT/...
1030 AM UPDATE...
FORECAST UPDATED TO LOWER DEWPOINTS FURTHER BELOW GUIDANCE
VALUES /AS WAS ALREADY BECOME EVIDENT/...AND ALSO TO KEEP UP WITH
FASTER-THAN-FORECAST WARMING THAT IS UNDERWAY. MODELS TYPICALLY
STRUGGLE WITH DEWPOINTS IN THIS SITUATION. DRY AIR FROM ALOFT
SHOULD HAVE NO PROBLEM MIXING DOWN...WITH MODEL SOUNDINGS
SUGGESTING STEEP LAPSE RATES/MIXING ALL THE WAY UP TO 700-600MB
LEVELS. AS ALREADY ACCOUNTED FOR IN FORECAST...GUSTY WINDS SHOULD
HAVE NO PROBLEM MIXING DOWN THROUGHOUT THIS AFTERNOON.
ALSO...VISIBLE SATELLITE SHOWS PLENTY OF CLOUDS CURRENTLY IN
CENTRAL TO NORTHERN ONTARIO AND MOST OF QUEBEC...BEHIND
APPROACHING SECONDARY COLD FRONT. AS DEPICTED BY 800-850MB RH
FIELDS IN RUC AND WRFARW MODELS...A BAND OF CLOUDS AT AROUND 4-5
KFT AGL SHOULD ACCOMPANY SECONDARY FRONT AS IT DROPS DOWN ACROSS
THE NORTHERN HALF OF THE AREA TONIGHT. SKY GRIDS HAVE BEEN UPDATED
ACCORDINGLY. THIS MAY HELP TO STAVE OFF PATCHY FROST THREAT IN
COLD AIR DRAINAGE PRONE VALLEYS OF THE NORTHEASTERN/EASTERN PARTS
OF THE AREA.
PREVIOUS DISCUSSION...
A SECONDARY COLD FRONT WILL DROP SOUTH OUT OF ONTARIO INTO NY LATE
TODAY. VERY DRY ATMOSPHERIC PROFILES WILL PRECLUDE ANY POSSIBILITY
FOR PRECIPITATION.
THE MAIN EFFECT OF THE FRONTAL APPROACH WILL BE TO INCREASE WINDS
DURING THE AFTERNOON HOURS. WITH HEALTHY BL-850MB WINDS PROGGED,
AND A WELL MIXED ATMOSPHERE EXPECTED, IT LOOKS LIKE A GOOD BET
FOR WIND GUSTS OF 20 TO 25 MPH THIS AFTERNOON.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
UL RIDGE BUILDS THROUGH THE OHIO VALLEY AND GREAT LAKES THIS
PERIOD. ATMOSPHERIC MOISTURE WILL REMAIN LOW OVER THE NORTHEASTERN
U.S. THROUGH SATURDAY NIGHT, WITH SLIGHTLY BELOW NORMAL 850MB
TEMPS OVERHEAD.
THE RESULT WILL BE A FAIR WEATHER PERIOD, WITH MILD SUNNY DAYS AND
COOL NIGHTS. CANNOT RULE OUT SOME UPPER 30S MINS TONIGHT AND
POSSIBLY FRIDAY NIGHT, ESPECIALLY IN THE SHELTERED VALLEYS OVER
THE EASTERN FA.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD
INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST
INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS.
TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER
LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE
NORTHEAST.
AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW
ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL
PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT
CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA.
FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS
FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE
WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH
TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED
NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL
AS UPPER LEVEL TROF RESIDES OVER REGION.
TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A
RETURN TO MORE SEASONAL TEMPS BY THURSDAY.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH THIS TAF PERIOD. SCATTERED
MID LEVEL CLOUDS WILL CLEAR BY EARLY EVENING BEFORE A SECONDARY
TROF DROPS THROUGH OVERNIGHT. THIS FEATURE WILL PRODUCE SCT/BKN
CLOUDS AROUND 4K FT. ON FRIDAY, JUST SCATTERED CU WILL PERSIST.
NORTHWEST WINDS AT 10-12 KNOTS GUSTING TO 25 KNOTS THEN
DECREASING TO 5 KNOTS THIS EVENING. NORTHWEST WINDS AROUND 10
KNOTS ON FRIDAY.
OUTLOOK...
FRI NIGHT THROUGH TUESDAY...PRIMARILY VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP/MDP
SHORT TERM...DJP
LONG TERM...RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1037 AM EDT THU MAY 16 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL CONTROL OUR WEATHER THROUGH SATURDAY,
BRINGING DRY CONDITIONS AND MILD DAYTIME TEMPERATURES TO NEW YORK
AND PENNSYLVANIA.
&&
.NEAR TERM /THROUGH TONIGHT/...
1030 AM UPDATE...
FORECAST UPDATED TO LOWER DEWPOINTS FURTHER BELOW GUIDANCE
VALUES /AS WAS ALREADY BECOME EVIDENT/...AND ALSO TO KEEP UP WITH
FASTER-THAN-FORECAST WARMING THAT IS UNDERWAY. MODELS TYPICALLY
STRUGGLE WITH DEWPOINTS IN THIS SITUATION. DRY AIR FROM ALOFT
SHOULD HAVE NO PROBLEM MIXING DOWN...WITH MODEL SOUNDINGS
SUGGESTING STEEP LAPSE RATES/MIXING ALL THE WAY UP TO 700-600MB
LEVELS. AS ALREADY ACCOUNTED FOR IN FORECAST...GUSTY WINDS SHOULD
HAVE NO PROBLEM MIXING DOWN THROUGHOUT THIS AFTERNOON.
ALSO...VISIBLE SATELLITE SHOWS PLENTY OF CLOUDS CURRENTLY IN
CENTRAL TO NORTHERN ONTARIO AND MOST OF QUEBEC...BEHIND
APPROACHING SECONDARY COLD FRONT. AS DEPICTED BY 800-850MB RH
FIELDS IN RUC AND WRFARW MODELS...A BAND OF CLOUDS AT AROUND 4-5
KFT AGL SHOULD ACCOMPANY SECONDARY FRONT AS IT DROPS DOWN ACROSS
THE NORTHERN HALF OF THE AREA TONIGHT. SKY GRIDS HAVE BEEN UPDATED
ACCORDINGLY. THIS MAY HELP TO STAVE OFF PATCHY FROST THREAT IN
COLD AIR DRAINAGE PRONE VALLEYS OF THE NORTHEASTERN/EASTERN PARTS
OF THE AREA.
PREVIOUS DISCUSSION...
A SECONDARY COLD FRONT WILL DROP SOUTH OUT OF ONTARIO INTO NY LATE
TODAY. VERY DRY ATMOSPHERIC PROFILES WILL PRECLUDE ANY POSSIBILITY
FOR PRECIPITATION.
THE MAIN EFFECT OF THE FRONTAL APPROACH WILL BE TO INCREASE WINDS
DURING THE AFTERNOON HOURS. WITH HEALTHY BL-850MB WINDS PROGGED,
AND A WELL MIXED ATMOSPHERE EXPECTED, IT LOOKS LIKE A GOOD BET
FOR WIND GUSTS OF 20 TO 25 MPH THIS AFTERNOON.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
UL RIDGE BUILDS THROUGH THE OHIO VALLEY AND GREAT LAKES THIS
PERIOD. ATMOSPHERIC MOISTURE WILL REMAIN LOW OVER THE NORTHEASTERN
U.S. THROUGH SATURDAY NIGHT, WITH SLIGHTLY BELOW NORMAL 850MB
TEMPS OVERHEAD.
THE RESULT WILL BE A FAIR WEATHER PERIOD, WITH MILD SUNNY DAYS AND
COOL NIGHTS. CANNOT RULE OUT SOME UPPER 30S MINS TONIGHT AND
POSSIBLY FRIDAY NIGHT, ESPECIALLY IN THE SHELTERED VALLEYS OVER
THE EASTERN FA.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
MODEL AGREEMENT THROUGH THE EXTENDED TIMEFRAME REMAINS LESS THAN
STELLAR THIS AFTERNOON WITH BOTH DETERMINISTIC LONG RANGE MODELS
DISAGREEING ON THE ARRIVAL TIMING OF NEXT WEEK/S UPPER RIDGE. MAIN
PROBLEM REMAINS UPPER BLOCKING SOUTH OF GREENLAND AND REMNANT
UPPER LOW WHICH IS NOW PASSING OFF TO OUR NORTH THIS AFTERNOON.
BOTH MODELS SHOW THIS FEATURE STALLING TO OUR EAST BY THE WEEKEND
ENSURING CYCLONIC NORTHWEST FLOW OVER OUR REGION FOR THE UPCOMING
WEEKEND. THE ECMWF REMAINS THE FASTER SOLUTION IN BRINGING DECENT
RIDGING ALOFT INTO OUR AREAS BY LATE SUN...WHILE THE GFS DELAYS
AND EVEN SUPPRESSES THE APPROACHING RIDGE WITH ITS SUGGESTION THAT
A MIDWEST UPPER LOW WILL DIG SOUTHEAST INTO THE WESTERN GREAT
LAKES. IN ANY EVENT...MAIN FRONTAL BOUNDARY LOOKS TO REMAIN
STALLED SOUTH OF THE FCST REGION THROUGH THE PERIOD WITH A GRADUAL
REDUCTION IN POPS MADE FOR THE UPCOMING WEEKEND. BEYOND
THIS...HAVE GENERALLY FOLLOWED WPC/S GUIDANCE TRENDS WHICH FAVORS A
FAIRLY DECENT WARM UP EARLY NEXT WEEK.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
VFR CONTS THRU THE PD. NW FLOW OF DRY AIR WILL CONT THRU THE PD
KEEPING SKIES CLR OR SCT AT WORST. WINDS WILL INCREASE AND BECOME
GUSTY DIURNALLY WITH MIXING...OTRW LTL CHG THRU THE 24 HR PD.
OUTLOOK...
FRI THROUGH MON...VFR.
&&
.FIRE WEATHER...
GUSTY WEST WINDS ARE FORECAST TODAY, WITH SUNNY SKIES AND LOW
DEW POINTS FORECAST. TEN HOUR FUEL LEVELS WILL NOT MEET RED FLAG
CRITERIA DUE TO FA WIDE GREEN UP. HOWEVER THERE WILL BE ENHANCED
FIRE SENSITIVITY DUE TO THE COMBINATION OF GUSTY WINDS AND DRY
ATMOSPHERE. MINIMUM HUMIDITY LEVELS AREAWIDE SHOULD GET INTO 20S
PERCENT RANGE. PEAK GUSTS OF 20-30 MPH CAN BE EXPECTED IN
NORTHEAST PA...AND 25-35 MPH OR SO IN CENTRAL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP/MDP
SHORT TERM...DJP
LONG TERM...CMG
AVIATION...DGM
FIRE WEATHER...DJP/MDP
AREA FORECAST DISCUSSION
NWS RALEIGH NC
819 PM EDT FRI MAY 17 2013
.SYNOPSIS...
A STATIONARY FRONT OVER NORTHERN NC TONIGHT AND SATURDAY WILL
RETREAT NORTHWARD THROUGH VA ON SUNDAY...BENEATH A TROUGH ALOFT THAT
WILL SLOWLY APPROACH AND CROSS CENTRAL NC THROUGH MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 255 PM FRIDAY...
THE LATEST SURFACE ANALYSIS SHOWED A SURFACE FRONT ACROSS NORTHERN
INDIANA AND OHIO...THEN BENDING SOUTHEAST ACROSS SOUTHWEST
PENNSYLVANIA TOWARD FAR NORTHEAST NORTH CAROLINA. ALONG AND JUST
AHEAD OF THE FRONT OVER NORTHEAST NORTH CAROLINA...INCLUDING THE
COASTAL PLAIN...INSTABILITY WAS HIGHEST WITH MIXED-LAYER CAPE ON THE
ORDER OF 500J/KG ON THE LATEST SPC MESOANALYSIS. GIVEN THE LIGHT
WIND FIELD CONVERGENCE WAS MEAGER...AND WHILE SURFACE DEW POINTS HAD
YET TO FALL AS FAR AS THE RAP FORECAST...THEY STILL HAVE FALLEN
SOLIDLY INTO THE 50S OVER MOST PARTS OF CENTRAL NORTH CAROLINA. THIS
HAS MADE IT DIFFICULT FOR ANY DEEP CONVECTION TO DEVELOP.
GIVEN THE DIFFERENCES IN THE MOISTURE GUIDANCE AS WELL AS THE OUTPUT
OF THE CONVECTION-ALLOWING MODELS...AND CONSIDERING THE NAM APPEARS
SO OUT OF TOLERANCE WITH ITS FORECAST SURFACE DEW POINTS...HAVE
LEANED TOWARD A CONSENSUS OF THE RAP AND GFS OVERNIGHT. THIS WOULD
SUPPORT THE BETTER CHANCES OF ANY SHOWERS OR THUNDERSTORMS OVERNIGHT
ALONG AND AHEAD OF THE SURFACE FRONT...MAINLY ALONG AND NORTH OF A
LINE FROM ABOUT KTDF TO KRWI. THIS IS WHERE THE RAP SHOWS LOW-LEVEL
MOISTURE POOLING AROUND AND AFTER 00Z...SUPPORTED MOST BY THE LOCAL
RALEIGH WRF REFLECTIVITY FORECAST. IN THE RELATIVELY MORE STABLE AIR
OVER THE SOUTHWEST PIEDMONT IN PARTICULAR...WILL KEEP CONDITIONS DRY
UNTIL THE OVERNIGHT HOURS...AND THEN ONLY NOTE A SLIGHT CHANCE OF A
SHOWER THERE AND ELSEWHERE ACROSS CENTRAL NORTH CAROLINA. IT SHOULD
BE NOTED THAT SOME OF THE GUIDANCE POPS...PARTICULARLY FROM THE
NAM...ARE QUITE HIGH OVERNIGHT...BUT THE NAM ALSO FORECASTS SURFACE
DEW POINTS GETTING NEAR 70 OVER PARTS OF THE NORTHWEST PIEDMONT BY
21Z...WHICH CURRENTLY SEEMS UNLIKELY. UNDER A CONTINUING MID-LEVEL
RIDGE AHEAD OF THE TROUGH MOVING EAST...WILL ANTICIPATE A DIURNAL
REDUCTION IN CHANCES FOR PRECIPITATION FOR ONE MORE NIGHT. OVERNIGHT
LOWS IN THE LOWER TO MID 60S.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 255 PM FRIDAY...
THE TROUGH ALOFT GRADUALLY MOVES INTO CENTRAL NORTH CAROLINA
SATURDAY AND SATURDAY NIGHT. WHILE DIFFERENCES CONTINUE WITH THE
DETAILS IN THE GUIDANCE...INCLUDING VARIOUS WRF OUTPUT...ON A LARGE
SCALE...MEAN RH INCREASES TO A MAXIMUM DURING THE PERIOD LATE
SATURDAY AFTERNOON IN THE NORTHWEST PIEDMONT...AND TO ABOUT U.S. 1
OR SO SATURDAY NIGHT. THE BEST LIFT IS NORTHWEST CLOSER TO THE UPPER
TROUGH...850MB THETA-E IS GREATEST IN CONJUNCTION WITH THE MEAN
RELATIVE HUMIDITY...AND BY LATE SATURDAY AFTERNOON AND SATURDAY
NIGHT...THE 850MB FLOW FROM THE SOUTHWEST INCREASES TO AROUND 25KT
FOCUSED OVER AND NEAR THE WESTERN PIEDMONT. BUFR SOUNDINGS
ESPECIALLY FROM THE GFS SHOW GREATER MOISTURE AND INSTABILITY WEST
COMPARED TO EAST IN CENTRAL NORTH CAROLINA. AS A RESULT...INSTEAD OF
TRYING TO INTERPRET THE VARIETY OF WRF TRENDS...HAVE FOLLOWED A
PRECIPITATION FORECAST LEANING MORE TOWARD LARGE-SCALE FEATURES.
THIS RESULTS IN MOSTLY CHANCE POPS FOR SATURDAY...BECOMING LIKELY IN
THE IMMEDIATE TRIAD BY LATE IN THE DAY AND SPREADING LIKELY POPS TO
AROUND U.S. 1 BY OVERNIGHT SATURDAY CLOSER TO 850MB LOW PRESSURE.
THE LEAST CHANCES WILL BE TOWARD KGSB AND KCTZ...WHERE OVERALL
MOISTURE AND LIFT ARE LEAST...CLOSER ALSO TO THE 850MB RIDGE JUST
OFFSHORE. THE GFS HAS FAIRLY ROBUST PRECIPITATION AMOUNTS IN THE
TRIAD OVERNIGHT SATURDAY AND THIS WILL HAVE TO BE WATCHED...BUT FOR
NOW WILL FORECAST AVERAGE PRECIPITATION AMOUNTS THERE AROUND 0.75
INCH FROM LATE SATURDAY AFTERNOON THROUGH SATURDAY NIGHT. HIGHS
SATURDAY NEAR 80 NORTHWEST TO THE UPPER 80S SOUTHEAST...WITH
OVERNIGHT LOWS SATURDAY NIGHT IN THE MID 60S.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 255 PM FRIDAY...
SUNDAY THROUGH MONDAY NIGHT: CONFIDENCE IN AN UNSETTLED WEATHER
PATTERN IS HIGH THROUGH MONDAY NIGHT...HOWEVER THE TIMING...COVERAGE
AND INTENSITY OF PRECIPITATION IS STILL AN ISSUE. AN UPPER LEVEL
SHORTWAVE DISTURBANCE ALONG THE RIDGE AXIS MOVING OVER CENTRAL NC ON
SUNDAY AND MONDAY WILL AID IN THE DEVELOPMENT OF SHOWERS AND STORMS
THROUGH THE PERIOD. AT H850 A TROUGH WILL EXTEND EAST FROM THE
PARENT LOW OVER THE MIDWEST AND INTO TN AND THE CAROLINAS THROUGH
MONDAY...WITH RIDGING TO THE NORTH FROM AN OFFSHORE HIGH. ALTHOUGH
THERE ARE STILL SOME DIFFERENCES BETWEEN THE MODELS AND FROM RUN TO
RUN...THE GFS AND ECMWF HAVE COME INTO BETTER AGREEMENT WITH RESPECT
TO THE STRENGTH AND CHARACTER OF THE SHORTWAVE LOW...THUS WILL
CONTINUE A BLEND OF THE TWO. AT THE SURFACE...THE GFS CONTINUES TO
SHOW A LOW DEVELOPING IN THE LEE OF THE ROCKIES THIS WEEKEND AND
DEEPENING AS IT MIGRATES SLOWLY EAST INTO EASTERN SD...EXTENDING SSE
THROUGH CENTRAL OK/TX...AND A TROUGH AXIS EXTENDING EAST INTO THE
MID ATLANTIC STATES. WARM MOIST SW FLOW OFF THE GULF WILL KEEP PWAT
VALUES IN THE 1.5 TO 2.0 INCH RANGE THROUGH MONDAY NIGHT FUELING THE
POTENTIAL FOR SOME SIGNIFICANT STORM TOTAL RAINFALL AMOUNTS GIVEN
THE WEAK STEERING FLOW EXPECTED. MODEL GENERATED MLCAPE IS OF THE
TALL AND SKINNY VARIETY...WITH VALUES OF 1000-1500 J/KG SUNDAY AND
MONDAY. COMBINED WITH 0-6 KM BULK SHEAR VALUES OF MAINLY 10-20
KTS...EXPECT CONVECTIVE MODE TO BE MAINLY DISORGANIZED PULSE TYPE
STORMS...ALTHOUGH AN ISOLATED STRONG STORM CANNOT BE RULED OUT. THE
BIGGER THREAT CONTINUES TO BE FROM POTENTIALLY HEAVY RAINFALL...
ESPECIALLY SUNDAY NIGHT AND MONDAY. GIVEN THE UNCERTAINTY REGARDING
PRECIP AMOUNTS...HAVE DECREASED STORM TOTAL RAINFALL TOTALS FROM THE
PREVIOUS FORECAST...HOWEVER WIDESPREAD 1-2 INCHES IS STILL LIKELY
THROUGH MONDAY NIGHT. HIGH TEMPERATURES THROUGH THIS PERIOD CONTINUE
TO BE DEPENDENT ON CLOUD COVER AND PRECIPITATION. FOR NOW...EXPECT
HIGHS IN THE UPPER 70S NORTH AND LOW TO MID 80S ACROSS THE EAST AND
SOUTH. OVERNIGHT LOWS WILL STAY MAINLY IN THE MID 60S.
TUESDAY THROUGH FRIDAY: AS THE SHORTWAVE MOVES NORTHEAST AWAY FROM
THE AREA ON TUESDAY...HIGH PRESSURE WILL BUILD INTO THE CAROLINAS
FROM THE ESE...WITH RETURN FLOW OFF THE ATLANTIC AND A SLIGHT
DECREASE IN FORECAST PWAT VALUES. DRY AIR ADVECTING IN AT THE MID
LEVELS SHOULD DECREASE RAINFALL CHANCES THROUGH WEDNESDAY ALTHOUGH
THE POSSIBILITY OF AN AFTERNOON SHOWER EXISTS. A MIDWEST LOW WILL
MOVE EAST TOWARD THE MID ATLANTIC DURING THIS TIME AND THE TROUGH
BECOMES ORIENTED MORE SW TO NE...WITH INCREASING PRECIPITATION
CHANCES ON THURSDAY AND FRIDAY. GIVEN THE DIFFERENCES BETWEEN THE
MODELS...THERE IS A GOOD DEAL OF UNCERTAINTY WITH RESPECT TO
PRECIPITATION MOVING AHEAD OF THE SYSTEM. FOR NOW WILL CARRY SLIGHT
CHANCES FOR SHOWERS AND STORMS DURING THE AFTERNOON HOURS THURSDAY
AND FRIDAY...WITH A DRY FORECAST FOR THE OVERNIGHT HOURS. HIGH TEMPS
TUESDAY AND WEDNESDAY IN THE MID TO UPPER 80S...DECREASING AGAIN
THROUGH FRIDAY...UPPER 70S TO LOW 80S. OVERNIGHT LOWS REMAIN STEADY
IN THE MID TO UPPER 60S.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 815 PM FRIDAY...
VFR CONDITIONS ARE EXPECTED FOR THE MAJORITY OF THE 00Z TAF
PERIOD...WITH THE FOLLOWING THREE RELATIVELY SHORT-DURATION
EXCEPTIONS: 1) VICINITY SHOWERS AT TRIAD TERMINALS FOR THE NEXT HOUR
OR SO... 2) MAINLY MVFR VISIBILITY RESTRICTIONS SAT MORNING...
PARTICULARLY WHERE RAIN HAS FALLEN IN THE VICINITY OF TRIAD
TERMINALS THIS AFTERNOON-EVENING...AND 3) A 30 TO 50 PERCENT CHANCE
OF SHOWERS AND STORMS SAT AFTERNOON-EVENING...WITH THE RELATIVE
HIGHEST CHANCE/COVERAGE NORTH OF KFAY. THOUGH THIS CONVECTION WILL
BE SCATTERED ABOUT SAT AFTERNOON...CONFIDENCE OF OCCURRENCE AT ANY
PARTICULAR TERMINAL IS TOO LOW TO INCLUDE A MULTI-HOUR PREVAILING
CONDITION OF SUCH AT THIS TIME RANGE. -MWS
BEYOND THE 18Z VALID TAF PERIOD...CHANCES FOR SHOWERS AND
THUNDERSTORMS GRADUALLY INCREASE...BECOMING LIKELY IN THE TRIAD BY
LATE SATURDAY AFTERNOON AND EXTENDING AT LEAST TO KRDU BY SATURDAY
NIGHT AS AN UPPER-LEVEL TROUGH MOVES EAST. ALONG WITH THE SUB-VFR
CONDITIONS THAT THE SHOWERS AND STORMS WOULD BRING...THERE IS A GOOD
CHANCE OF IFR CONDITIONS IN LOW CLOUDS AT LEAST TOWARD KINT AND KGSO
LATE SATURDAY NIGHT INTO SUNDAY MORNING...WITH SOME CHANCE OF THOSE
CLOUDS EXTENDING ACROSS THE REST OF CENTRAL NORTH CAROLINA. PERIODS
OF MVFR AND IFR CONDITIONS IN LOW CLOUDS...OR SHOWERS OR
THUNDERSTORMS...CONTINUE INTO EARLY NEXT WEEK...WITH THE BEST
POTENTIAL FOR SUSTAINED VFR CONDITIONS TUESDAY AFTERNOON INTO THE
OVERNIGHT HOURS OF TUESDAY...AND AGAIN AFTER MIXING DURING THE DAY
WEDNESDAY. -DJF
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...DJF
SHORT TERM...DJF
LONG TERM...KMC
AVIATION...MWS/DJF
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
928 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 927 PM CDT FRI MAY 17 2013
ADJUSTED POPS/WX BASED ON CURRENT RADAR TIMING. STORMS FIRING
ALONG THE 850MB WARM AIR ADVECTION IN CENTRAL MN WILL CLIP OUR
SOUTHEASTERN COUNTIES...SO INCLUDED A SCATTERED MENTION FOR THE
REST OF THE EVENING. STORMS FIRING OVER WESTERN ND AND SD WILL
MOVE NORTHEASTWARD INTO THE SOUTHERN RED RIVER VALLEY LATER
TONIGHT. IF CURRENT MOTION HOLDS...THE ACTIVITY SHOULD ARRIVE AT
OUR SOUTHERN BORDER AROUND MIDNIGHT AND MOVE NORTHEASTWARD
THROUGHOUT THE EARLY MORNING HOURS. TWEAKED TIMING OF POPS MOVING
INTO THE AREA WITH LIKELY WORDING TRANSITIONING FROM THE SOUTH
JUST AFTER MIDNIGHT TO THE NORTH BY TOMORROW MORNING. ELEVATED CAP
VALUES ARE AROUND 1000 J/KG ACCORDING TO THE SPC MESOANALYSIS.
THINK THAT THE BEST LLJ WILL STAY TO OUR SOUTH BUT SOME ISOLATED
SEVERE HAIL OR WIND IS NOT OUT OF THE QUESTION AROUND THE 06-12Z
TIME FRAME. HOWEVER...CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE IN
THE GRIDS AT THIS POINT SO WILL JUST KEEP GENERAL THUNDER GOING.
UPDATE ISSUED AT 652 PM CDT FRI MAY 17 2013
ADJUSTED POPS ALONG THE CANADIAN BORDER FOR THE NEXT FEW HOURS TO
ACCOUNT FOR THE WEAK SHOWERS/SPRINKLES DEVELOPING IN THAT AREA.
HOWEVER...THE MAIN PRECIP IS WELL TO OUR SOUTH...SO KEPT THE HIGH
POPS RESERVED FOR AFTER MIDNIGHT AS THE GOING FORECAST HAS.
TWEAKED CLOUDS TO INCLUDE CLEARING IN OUR SOUTHWESTERN COUNTIES
BUT THAT WILL NOT LAST LONG AS BLOW OFF FROM CONVECTION FROM OUR
SOUTHWEST BEGINS TO MOVE IN. SHOULD BE TOTALLY CLOUDY AFTER
MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM CDT FRI MAY 17 2013
THE MAIN CONCERNS WILL BE HEAVY RAIN AND SEVERE POTENTIAL. 12Z
MODELS IN DECENT AGREEMENT WITH SYNOPTIC FEATURES...BUT STILL
ENOUGH DIFFERENCES THAT CONFIDENCE IS LOW WITH DETAILS.
WEST COAST TROUGH WILL GRADUALLY PROPAGATE EAST WITH MULTIPLE
SHORTWAVES EJECTING INTO THE REGION. HARD TO PINPOINT EXACTLY WHEN
AND WHERE THE BEST THUNDER CHANCES WILL BE...BUT THE MODELS DO
OFFER A COUPLE STRONGER SIGNALS. THE FIRST BEST CHANCE IS TONIGHT
INTO SATURDAY MORNING AS MENTIONED IN THE PREVIOUS AFD (1243PM).
18Z HRRR DOES INDICATE A THUNDERSTORM COMPLEX MOVING INTO THE
SOUTHERN FA AFTER 06Z...ALONG WITH WITH ISOLATED STRONGER STORMS.
THIS COMPLEX SHOULD MOVE THROUGH FAIRLY QUICKLY...WITH UP TO 0.5
INCH AREAL QPF POSSIBLE.
THINKING THERE WILL BE A BRIEF BREAK IN ACTIVITY ON SATURDAY.
SEVERE POTENTIAL WILL DEPEND ON HOW FAR NORTH THE SURFACE WARM
FRONT WILL MAKE IT BY SATURDAY AFTERNOON. THE GEM/GFS BRING THIS
FEATURE MUCH FURTHER NORTH THAN OTHER MODELS (LIKELY BECAUSE THEY
ARE STRONGER WITH A SHORTWAVE INTO SOUTHERN CANADA). AT ANY
RATE...GIVEN THIS TIME OF YEAR WITHOUT EVAPOTRANSPIRATION...THE
NAM SEEMS TO HAVE THE CORRECT IDEA INDICATING MLCAPE 1000-1500
J/KG WITHIN THE WARM SECTOR. THIS INSTABILITY ALONG WITH DEEP
LAYER SHEAR 30-35 KNOTS SHOULD BE ENOUGH FOR LIMITED SEVERE
POTENTIAL WITHIN THE WARM SECTOR AS THE COLD FRONT SLOWLY
PROPAGATES EAST INTO THE EVENING HOURS.
THE BEST CHANCE FOR FLASH FLOODING POTENTIAL WOULD BE SATURDAY
EVENING AND OVERNIGHT ALONG THE SLOW MOVING BOUNDARY. THE BIGGEST
QUESTIONS AT THIS POINT WILL BE THE EXACT LOCATION OF THIS
FEATURE...AND HOW QUICKLY IT WILL MOVE TO THE EAST. NOT ENOUGH
CONFIDENCE FOR A FLASH FLOOD WATCH AT THIS POINT...BUT THERE IS A
SLIGHT RISK FOR FLASH FLOODING ALONG AND EAST OF THE VALLEY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 PM CDT FRI MAY 17 2013
SUNDAY-MONDAY...UPPER LOW WILL CLOSE OFF JUST SOUTH OF THE FA AND
BRING PERIODIC SHOWERS AND THUNDERSTORMS TO THE REGION.
INSTABILITY IS MUCH WEAKER BY THIS TIME...BUT GIVEN HIGH PWATS AN
ADDITIONAL 1-2 INCHES OF RAINFALL IS POSSIBLE (ESPECIALLY THE
SOUTHERN HALF OF THE FA). THIS RAINFALL WOULD OVER A COUPLE DAYS
AND ANY FLOOD THREAT IS DEPENDENT ON WHAT OCCURS SATURDAY/SATURDAY
NIGHT.
MONDAY NIGHT-FRIDAY...12Z GFS/12Z ECMWF IN PRETTY GOOD AGREEMENT
IN SHOWING THE 500 MB LOW OVER EASTERN SD/MN REGION TUESDAY THEN
DRIFTING A BIT SOUTH AND EAST WEDNESDAY AND THEN EAST OF THE AREA
THURSDAY. LOOK FOR A CONTINUED HIGH THREAT FOR SHOWERS
TUESDAY...DIMINISHING ON WEDNESDAY. A 500 MB RIDGE WILL BUILD IN
BEHIND THE LOW FOR THE END OF THE WEEK WITH DRY WEATHER RETURNING.
LOOK FOR TEMPS TO BIT A BIT BELOW NORMAL WITH THE CLOUDS/RAIN TUE-
WED THEN RETURN TO CLOSE TO NORMAL LEVELS BY LATE WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 652 PM CDT FRI MAY 17 2013
VFR CLOUDS WILL CONTINUE OVER MUCH OF THE AREA...BUT SOME MVFR
CEILINGS OVER THE SOUTHEASTERN FORECAST AREA WILL BEGIN TO SPREAD
NORTH AND WEST LATER ON TONIGHT. HAVE KFAR DECREASING TO MVFR
AFTER MIDNIGHT AND THE OTHER SITES MORE TOWARDS MORNING. SHOWERS
AND A FEW THUNDERSTORMS WILL MOVE IN AFTER MIDNIGHT...WITH THE
BEST CONVECTION IN THE SOUTH AROUND KFAR WHILE THE NORTHERN SITES
WILL BE MORE SHOWERY. WINDS WILL SHIFT TO A MORE SOUTHERLY
DIRECTION DURING THE DAY TOMORROW AS A WARM FRONT LIFTS NORTH INTO
THE AREA...ALTHOUGH THERE IS STILL SOME UNCERTAINTY AS TO EXACTLY
WHERE THE BOUNDARY WILL END UP. FOR NOW HAVE IT GOING PAST OUR
NORTHERN TAF SITES BY LATE IN THE PERIOD BUT THE BOUNDARY MAY
STALL OUT AND LEAVE THEM IN EASTERLY WINDS AND MORE RAIN. THINK
THAT THERE SHOULD BE SOME BRIEF IMPROVEMENT TO VFR IN MOST SITES
DURING THE LATE MORNING OR AFTERNOON ALTHOUGH MUCH WILL DEPEND ON
HOW EARLY MORNING CONVECTION PLAYS OUT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...TG
LONG TERM...TG/RIDDLE
AVIATION...JR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
652 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 652 PM CDT FRI MAY 17 2013
ADJUSTED POPS ALONG THE CANADIAN BORDER FOR THE NEXT FEW HOURS TO
ACCOUNT FOR THE WEAK SHOWERS/SPRINKLES DEVELOPING IN THAT AREA.
HOWEVER...THE MAIN PRECIP IS WELL TO OUR SOUTH...SO KEPT THE HIGH
POPS RESERVED FOR AFTER MIDNIGHT AS THE GOING FORECAST HAS.
TWEAKED CLOUDS TO INCLUDE CLEARING IN OUR SOUTHWESTERN COUNTIES
BUT THAT WILL NOT LAST LONG AS BLOW OFF FROM CONVECTION FROM OUR
SOUTHWEST BEGINS TO MOVE IN. SHOULD BE TOTALLY CLOUDY AFTER
MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM CDT FRI MAY 17 2013
THE MAIN CONCERNS WILL BE HEAVY RAIN AND SEVERE POTENTIAL. 12Z
MODELS IN DECENT AGREEMENT WITH SYNOPTIC FEATURES...BUT STILL
ENOUGH DIFFERENCES THAT CONFIDENCE IS LOW WITH DETAILS.
WEST COAST TROUGH WILL GRADUALLY PROPAGATE EAST WITH MULTIPLE
SHORTWAVES EJECTING INTO THE REGION. HARD TO PINPOINT EXACTLY WHEN
AND WHERE THE BEST THUNDER CHANCES WILL BE...BUT THE MODELS DO
OFFER A COUPLE STRONGER SIGNALS. THE FIRST BEST CHANCE IS TONIGHT
INTO SATURDAY MORNING AS MENTIONED IN THE PREVIOUS AFD (1243PM).
18Z HRRR DOES INDICATE A THUNDERSTORM COMPLEX MOVING INTO THE
SOUTHERN FA AFTER 06Z...ALONG WITH WITH ISOLATED STRONGER STORMS.
THIS COMPLEX SHOULD MOVE THROUGH FAIRLY QUICKLY...WITH UP TO 0.5
INCH AREAL QPF POSSIBLE.
THINKING THERE WILL BE A BRIEF BREAK IN ACTIVITY ON SATURDAY.
SEVERE POTENTIAL WILL DEPEND ON HOW FAR NORTH THE SURFACE WARM
FRONT WILL MAKE IT BY SATURDAY AFTERNOON. THE GEM/GFS BRING THIS
FEATURE MUCH FURTHER NORTH THAN OTHER MODELS (LIKELY BECAUSE THEY
ARE STRONGER WITH A SHORTWAVE INTO SOUTHERN CANADA). AT ANY
RATE...GIVEN THIS TIME OF YEAR WITHOUT EVAPOTRANSPIRATION...THE
NAM SEEMS TO HAVE THE CORRECT IDEA INDICATING MLCAPE 1000-1500
J/KG WITHIN THE WARM SECTOR. THIS INSTABILITY ALONG WITH DEEP
LAYER SHEAR 30-35 KNOTS SHOULD BE ENOUGH FOR LIMITED SEVERE
POTENTIAL WITHIN THE WARM SECTOR AS THE COLD FRONT SLOWLY
PROPAGATES EAST INTO THE EVENING HOURS.
THE BEST CHANCE FOR FLASH FLOODING POTENTIAL WOULD BE SATURDAY
EVENING AND OVERNIGHT ALONG THE SLOW MOVING BOUNDARY. THE BIGGEST
QUESTIONS AT THIS POINT WILL BE THE EXACT LOCATION OF THIS
FEATURE...AND HOW QUICKLY IT WILL MOVE TO THE EAST. NOT ENOUGH
CONFIDENCE FOR A FLASH FLOOD WATCH AT THIS POINT...BUT THERE IS A
SLIGHT RISK FOR FLASH FLOODING ALONG AND EAST OF THE VALLEY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 PM CDT FRI MAY 17 2013
SUNDAY-MONDAY...UPPER LOW WILL CLOSE OFF JUST SOUTH OF THE FA AND
BRING PERIODIC SHOWERS AND THUNDERSTORMS TO THE REGION.
INSTABILITY IS MUCH WEAKER BY THIS TIME...BUT GIVEN HIGH PWATS AN
ADDITIONAL 1-2 INCHES OF RAINFALL IS POSSIBLE (ESPECIALLY THE
SOUTHERN HALF OF THE FA). THIS RAINFALL WOULD OVER A COUPLE DAYS
AND ANY FLOOD THREAT IS DEPENDENT ON WHAT OCCURS SATURDAY/SATURDAY
NIGHT.
MONDAY NIGHT-FRIDAY...12Z GFS/12Z ECMWF IN PRETTY GOOD AGREEMENT
IN SHOWING THE 500 MB LOW OVER EASTERN SD/MN REGION TUESDAY THEN
DRIFTING A BIT SOUTH AND EAST WEDNESDAY AND THEN EAST OF THE AREA
THURSDAY. LOOK FOR A CONTINUED HIGH THREAT FOR SHOWERS
TUESDAY...DIMINISHING ON WEDNESDAY. A 500 MB RIDGE WILL BUILD IN
BEHIND THE LOW FOR THE END OF THE WEEK WITH DRY WEATHER RETURNING.
LOOK FOR TEMPS TO BIT A BIT BELOW NORMAL WITH THE CLOUDS/RAIN TUE-
WED THEN RETURN TO CLOSE TO NORMAL LEVELS BY LATE WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 652 PM CDT FRI MAY 17 2013
VFR CLOUDS WILL CONTINUE OVER MUCH OF THE AREA...BUT SOME MVFR
CEILINGS OVER THE SOUTHEASTERN FORECAST AREA WILL BEGIN TO SPREAD
NORTH AND WEST LATER ON TONIGHT. HAVE KFAR DECREASING TO MVFR
AFTER MIDNIGHT AND THE OTHER SITES MORE TOWARDS MORNING. SHOWERS
AND A FEW THUNDERSTORMS WILL MOVE IN AFTER MIDNIGHT...WITH THE
BEST CONVECTION IN THE SOUTH AROUND KFAR WHILE THE NORTHERN SITES
WILL BE MORE SHOWERY. WINDS WILL SHIFT TO A MORE SOUTHERLY
DIRECTION DURING THE DAY TOMORROW AS A WARM FRONT LIFTS NORTH INTO
THE AREA...ALTHOUGH THERE IS STILL SOME UNCERTAINTY AS TO EXACTLY
WHERE THE BOUNDARY WILL END UP. FOR NOW HAVE IT GOING PAST OUR
NORTHERN TAF SITES BY LATE IN THE PERIOD BUT THE BOUNDARY MAY
STALL OUT AND LEAVE THEM IN EASTERLY WINDS AND MORE RAIN. THINK
THAT THERE SHOULD BE SOME BRIEF IMPROVEMENT TO VFR IN MOST SITES
DURING THE LATE MORNING OR AFTERNOON ALTHOUGH MUCH WILL DEPEND ON
HOW EARLY MORNING CONVECTION PLAYS OUT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...TG
LONG TERM...TG/RIDDLE
AVIATION...JR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
154 AM EDT THU MAY 16 2013
.SYNOPSIS...
A COLD FRONT JUST SOUTH OF THE LAKESHORE WILL PUSH INTO CENTRAL OHIO
TONIGHT AND THEN STALL. THE FRONT WILL LIFT NORTH AS A WARM FRONT
THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
COLD FRONT CURRENTLY SOUTH OF THE LAKESHORE. A COUPLE OF SHOWERS
HAVE POPPED UP JUST SOUTH OF KNOX COUNTY. WILL KEEP THE SLIGHT
CHANCE FOR A SHOWER/TS FROM FINDLAY TO MILLERSBURG. HRRR AND RAP
WANT TO PAINT SOME QPF TONIGHT. WITH BOUNDARY IN THE VICINITY AND
A LITTLE BIT OF ENERGY UPSTREAM...DID NOT WANT A COMPLETELY DRY
FORECAST. FOR TEMPS WENT UPPER 40S TO THE MID 50S. THERE IS ENOUGH
UPSTREAM CLOUDINESS TO GIVE US A VARIABLY CLOUDY OVERNIGHT.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
MODELS CONTINUE TO STALL THE FRONT WELL SOUTH OF THE AREA. GFS A
LITTLE SLOWER TODAY MOVING THE FRONT NORTH. EXCEPT FOR THE EXTREME
SW PORTION OF THE FORECAST AREA REMOVED MENTION OF POPS FOR FRIDAY
AND FRIDAY NIGHT. MODELS STILL IN CONFLICT FOR SATURDAY. ECMWF
KEEPS FRONT SOUTH OF THE AREA ON SATURDAY WHILE GFS CONTINUES TO
HAVE THE FRONT ACROSS THE AREA. FOR NOW SEE NO REASON TO START FLIP
FLOPPING FORECASTS THIS FAR OUT WHEN THINGS ARE STILL IN DOUBT. SO
FOR NOW KEPT CHANCE POPS GOING FOR SATURDAY.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
THE RIDGE IS STILL PROGGED TO BUILD ACROSS THE AREA THIS WEEKEND
THROUGH EARLY NEXT WEEK. THE CHANCES OF SHOWERS/STORMS SHOULD
DIMINISH UNDER THE BUILDING RIDGE. CANNOT TOTALLY RULE OUT OUT A
SHOWER OR THUNDERSTORM GIVEN THE OLD FRONTAL BOUNDARY OR SOME
OUTFLOW/MESO BOUNDARY... INCREASING HEAT ETC...BUT FOR THE
MOST PART SUNDAY AND MONDAY SHOULD BE WARM AND MOSTLY RAIN FREE. CUT
BACK ON THE 12 HOUR POP SUNDAY/MONDAY MOSTLY TO 15 TO 25 PERCENT.
THIS WILL BE "SLIGHT CHANCE" IN MOST FORECASTS WHICH DOES NOT SHOW
UP IN MOST OF OUR TEXT FORECASTS (AFTER THE FIRST DAY).
BY THE MIDDLE OF NEXT WEEK THE NEXT FRONT FROM THE WEST SHOULD WORK
INTO THE AREA. IT WILL LIKELY NOT BE IN A HURRY TO MOVE EAST AS A
TROUGH ALOFT IS PROGGED TO BE DEEPENING IN THE MIDDLE OF THE
COUNTRY. WILL HAVE A HIGHER CHANCE OF SHOWERS AND THUNDERSTORMS BY
TUESDAY AND WEDNESDAY. WILL BEGIN TO CUT BACK ON TEMPERATURES BY
NEXT WEDNESDAY GIVEN THE INCREASE IN CLOUDS AND SHOWERS.
FORECAST HIGHS WILL BE ABOVE GUIDANCE GIVEN THE BIG RIDGE AND THE
TIME OF YEAR. HIGHS 75 TO 80 SUNDAY...AROUND 80 OR IN THE LOWER 80S
MONDAY AND TUESDAY...THEN 70S WEDNESDAY. LOWS GENERALLY MID 50S TO
THE LOWER 60S.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
FRONTAL BOUNDARY IS NEARLY STATIONARY ACROSS THE SOUTHERN PORTION
OF THE FORECAST AREA AND THUNDERSTORMS CONTINUE TO DEVELOP ALONG
THE LINE. MANSFIELD WILL BE THE ONLY SITE AFFECTED BY THE
CONVECTION AND SHOULD BE BRIEF.
OTHERWISE...CLEARING WILL WORK INTO THE AREA THROUGH THE REST OF
THE NIGHT INTO TODAY. WINDS SHOULD BE LIGHT AND VARIABLE BECOMING
NORTHEAST BY THE END OF THE PERIOD.
.OUTLOOK... NON-VFR POSSIBLE IN SHOWERS OR THUNDERSTORMS
FRIDAY NIGHT THROUGH SUNDAY.
&&
.MARINE...
THE WINDS AND WAVES DECREASED ON SCHEDULE. WILL LET THE SMALL CRAFT
ADVISORY EXPIRE ON THE EAST END. ONLY MINOR CHANGES MADE TO THE
OVERNIGHT FORECAST.
HIGH PRESSURE WILL SLOWLY BUILD EAST ACROSS THE LAKE FROM THURSDAY
THROUGH THE WEEKEND. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THIS
TIME WITH STABLE CONDITIONS ON THE LAKE. WINDS WILL GENERALLY BE
LESS THAN 15 KNOTS WITH WAVES LESS THAN 2 FEET. LOW PRESSURE WILL
SLOWLY APPROACH THE REGION FROM THE WEST EARLY NEXT WEEK BRINGING
INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DJB
NEAR TERM...DJB/OUDEMAN
SHORT TERM...DJB
LONG TERM...KOSARIK
AVIATION...LOMBARDY
MARINE...KEC/KIELTYKA
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
742 AM EDT THU MAY 16 2013
.SYNOPSIS...
AN WEST-EAST FRONTAL BOUNDARY ALONG THE MASON DIXON LINE EARLY
THIS MORNING WILL SINK SOUTHWARD INTO THE CENTRAL APPALACHIANS AND
BECOME QUASI-STATIONARY...PIVOTING TO A NW-SE ORIENTATION.
MEANWHILE...HIGH PRESSURE WILL MIGRATE EASTWARD ACROSS
SOUTHEASTERN CANADA WITH ONSHORE FLOW DEVELOPING ACROSS THE MID-
ATLANTIC REGION. THE FRONTAL BOUNDARY WILL SLOWLY PUSH BACK TO THE
NORTH AS A WARM FRONT OVER THE WEEKEND...AND LIFT NORTH OF THE
AREA BY EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
08Z SFC ANALYSIS PLACES QUASI-STATIONARY FRONT FROM SOUTHERN PA
WESTWARD TO SE IOWA. MOST CONVECTIVELY ACTIVE PORTION OF THIS FRONT
IS OVR SE OHIO/SW PA AT 08Z...THE RESULT OF LG SCALE FORCING AHEAD
OF SHORTWAVE MOVING OVR THE E GRT LKS. AS THIS FEATURE TRACKS
EAST...EXPECT THE BEST CHC OF SHRA AND A FEW TSRA TO SHIFT FROM THE
LAUREL HIGHLANDS TO THE LOWER SUSQ VALLEY BY 12Z. LATEST RAP AND
NAMPARA SIMULATED RADAR DATA BOTH INDICATE A SIMILAR SCENARIO
PLAYING OUT EARLY THIS AM.
SHORTWAVE WILL PASS EAST OF THE AREA BY LATE AM...WITH ENOUGH OF A
NWRLY FLOW BEHIND IT TO PUSH THE SFC FRONT JUST SOUTH OF THE MASON
DIXON LINE BY THIS AFTN. DIURNAL HEATING/DESTABILIZATION...COMBINED
WITH APPROACH OF NEXT SHORTWAVE OVR THE GRT LKS...SHOULD CAUSE A NEW
ROUND OF CONVECTION TO FIRE ALONG FRONT JUST SOUTH OF PA THIS AFTN.
WILL MAINTAIN ONLY A SLIGHT CHC ALONG OUR S TIER COUNTIES.
ALTHOUGH TODAY WILL DAWN MCLDY ACROSS SOUTHERN PA...A GOOD DEAL OF
SUNSHINE APPEARS LIKELY EVERYWHERE BY AFTN...AS WNW FLOW DRAWS DRIER
AIR INTO THE STATE. ENS MEAN 8H TEMPS OF ARND 13C SHOULD SUPPORT
HIGH TEMPS FROM THE M70S OVR THE ALLEGHENY PLATEAU...TO THE L80S IN
THE SUSQ VALLEY.
ALL MDL DATA INDICATING HIGH PRES RIDGE AND ASSOC DRY AIR MASS NOSES
SEWRD INTO PA TONIGHT...BRINGING MCLEAR SKIES AND LIGHT WINDS TO ALL
OF CENTRAL PA. THE DRIEST AIR...AS DEPICTED BY GEFS NEGATIVE PWAT
ANOMALIES...REMAIN ACROSS THE NORTHERN HALF OF THE STATE...WHERE
READINGS ARE LIKELY TO DIP INTO THE M/U30S. CAN/T RULE OUT SOME
PATCHY FROST UP THERE...BUT GROWING SEASON HAS NOT OFFICIALLY BEGUN
UP THERE...SO NO ADVISORY NEEDED.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
SFC HIGH PRES WILL SLIDE EWD FROM ONTARIO TO THE MARITIMES BY 12Z
SUNDAY...WITH ONSHORE FLOW DEVELOPING ACRS THE MID-ATLC STATES.
EXPECT SFC RIDGING AND LACK OF ANY SIGNIFICANT MID-UPPER LEVEL
FORCING TO LIMIT PCPN THROUGH MOST OF THE PERIOD. THE HIGHEST POPS
ARE OVER THE SERN ZONES SAT NGT AS AN UPPER LEVEL WAVE DRIFTS EWD
ACRS KY/TN INTO THE CNTRL APPLCHNS AND INTERACTS WITH ONSHORE MSTR
FEED INTERSECTING RETREATING Q-STNRY/WARM FRONT LIFTING NWD OVER
THE MID-ATLC. EXPECT LOW CLOUDS TO DEVELOP FROM SOUTH TO NORTH ON
SAT NGT IN SELY FLOW REGIME. TEMPS WILL BE WARMER ON FRIDAY WITH
MORE SUN.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
GUIDANCE CONTINUES TO TREND COOLER FOR SUNDAY WITH HIGHS IN THE
MID-UPPER 60S...AS MOIST ONSHORE FLOW STRENGTHENS /-2SD 850MB U
WIND ANOMALY IN GEFS/ AND BRINGS EXTENSIVE CLOUD COVER TO THE
REGION. MDL LI PROGS SHOW A CAD PATTERN IN THE LOW-LEVELS AS THE
WARM FRONT PIVOTS AND STALLS ALONG THE ALLEGHENY FRONT. WITH
STABLE CONDITIONS EXPECTED...CHANGED WX TYPE TO LGT RAIN AS
INSTABILITY SHOULD BE LOCATED WEST OF THE MTNS. FOCUS FOR PCPN
INTO MONDAY SHOULD REMAIN SOUTH OF PA OVER THE VA/NC IN CONJCT
WITH UPPER LEVEL WAVE AND MAX PWAT ANOM NR +2SD. HIGHEST POPS ARE
AGAIN OVER THE ERN 1/2 OF THE CWA AS SELY FLOW CONTS TO IMPINGE ON
SLOWLY RETREATING/DIFFUSE N-S WARM FRONT.
THE LG SCALE PATTERN IS FCST TO TURN DECIDEDLY MORE AMPLIFIED NEXT
WEEK...WITH THE MAIN SYNOPTIC FEATURE OF INTEREST BEING AN UPPER
LOW OVER THE NRN PLAINS/UPR MS VLY. H5 HGTS SHOULD RISE DOWNSTREAM
OF THIS SYSTEM...WITH CENTRAL PA LKLY BREAKING INTO THE WARM
SECTOR BY NEXT TUES AS THE PESKY WARM FRONT LIFTS NORTH INTO NEW
ENGLAND. THIS SHOULD AFFORD ONE OR TWO VERY WARM LATE SPRING DAYS
WITH HIGHS 75-80F. THERE IS A HIGH SPREAD BETWEEN THE GFS/ECMWF
CONCERNING THE POTENTIAL UPPER MIDWEST CUT-OFF. THEREFORE UTILIZED
A 50/50 BLEND OF THEIR RESPECTIVE MOS PRODUCTS FOR THE DAY 5-7
FCST.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
A SLOW-MOVING COLD FRONT WILL BE ACCOMPANIED BY A ROUND OF SHRA
AND PERHAPS EVEN AN ISOLATED TSRA EARLY THIS MORNING ACROSS THE
SOUTHERN PA AIRFIELDS. 11Z RADAR LOOP SUGGESTS AOO/JST/MDT WILL
LIKELY IMPROVE TO VFR BTWN 12Z-13Z....WHILE SHRA/REDUCED VSBYS
MAY LINGER AT LNS UNTIL 13Z-14Z.
BY LATE MORNING...THE FRONTAL BOUNDARY SHOULD SHIFT SOUTH OF
PA...RESULTING IN A HIGH DEGREE OF CONFIDENCE IN VFR CONDS ACROSS
THE ENTIRE STATE.
.OUTLOOK...
FRI-SUN...NO SIG WX EXPECTED.
MON...AM LOW CIGS POSSIBLE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
601 AM EDT THU MAY 16 2013
.SYNOPSIS...
AN WEST-EAST FRONTAL BOUNDARY ALONG THE MASON DIXON LINE EARLY
THIS MORNING WILL SINK SOUTHWARD INTO THE CENTRAL APPALACHIANS AND
BECOME QUASI-STATIONARY...PIVOTING TO A NW-SE ORIENTATION.
MEANWHILE...HIGH PRESSURE WILL MIGRATE EASTWARD ACROSS
SOUTHEASTERN CANADA WITH ONSHORE FLOW DEVELOPING ACROSS THE MID-
ATLANTIC REGION. THE FRONTAL BOUNDARY WILL SLOWLY PUSH BACK TO THE
NORTH AS A WARM FRONT OVER THE WEEKEND...AND LIFT NORTH OF THE
AREA BY EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
08Z SFC ANALYSIS PLACES QUASI-STATIONARY FRONT FROM SOUTHERN PA
WESTWARD TO SE IOWA. MOST CONVECTIVELY ACTIVE PORTION OF THIS FRONT
IS OVR SE OHIO/SW PA AT 08Z...THE RESULT OF LG SCALE FORCING AHEAD
OF SHORTWAVE MOVING OVR THE E GRT LKS. AS THIS FEATURE TRACKS
EAST...EXPECT THE BEST CHC OF SHRA AND A FEW TSRA TO SHIFT FROM THE
LAUREL HIGHLANDS TO THE LOWER SUSQ VALLEY BY 12Z. LATEST RAP AND
NAMPARA SIMULATED RADAR DATA BOTH INDICATE A SIMILAR SCENARIO
PLAYING OUT EARLY THIS AM.
SHORTWAVE WILL PASS EAST OF THE AREA BY LATE AM...WITH ENOUGH OF A
NWRLY FLOW BEHIND IT TO PUSH THE SFC FRONT JUST SOUTH OF THE MASON
DIXON LINE BY THIS AFTN. DIURNAL HEATING/DESTABILIZATION...COMBINED
WITH APPROACH OF NEXT SHORTWAVE OVR THE GRT LKS...SHOULD CAUSE A NEW
ROUND OF CONVECTION TO FIRE ALONG FRONT JUST SOUTH OF PA THIS AFTN.
WILL MAINTAIN ONLY A SLIGHT CHC ALONG OUR S TIER COUNTIES.
ALTHOUGH TODAY WILL DAWN MCLDY ACROSS SOUTHERN PA...A GOOD DEAL OF
SUNSHINE APPEARS LIKELY EVERYWHERE BY AFTN...AS WNW FLOW DRAWS DRIER
AIR INTO THE STATE. ENS MEAN 8H TEMPS OF ARND 13C SHOULD SUPPORT
HIGH TEMPS FROM THE M70S OVR THE ALLEGHENY PLATEAU...TO THE L80S IN
THE SUSQ VALLEY.
ALL MDL DATA INDICATING HIGH PRES RIDGE AND ASSOC DRY AIR MASS NOSES
SEWRD INTO PA TONIGHT...BRINGING MCLEAR SKIES AND LIGHT WINDS TO ALL
OF CENTRAL PA. THE DRIEST AIR...AS DEPICTED BY GEFS NEGATIVE PWAT
ANOMALIES...REMAIN ACROSS THE NORTHERN HALF OF THE STATE...WHERE
READINGS ARE LIKELY TO DIP INTO THE M/U30S. CAN/T RULE OUT SOME
PATCHY FROST UP THERE...BUT GROWING SEASON HAS NOT OFFICIALLY BEGUN
UP THERE...SO NO ADVISORY NEEDED.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
SFC HIGH PRES WILL SLIDE EWD FROM ONTARIO TO THE MARITIMES BY 12Z
SUNDAY...WITH ONSHORE FLOW DEVELOPING ACRS THE MID-ATLC STATES.
EXPECT SFC RIDGING AND LACK OF ANY SIGNIFICANT MID-UPPER LEVEL
FORCING TO LIMIT PCPN THROUGH MOST OF THE PERIOD. THE HIGHEST POPS
ARE OVER THE SERN ZONES SAT NGT AS AN UPPER LEVEL WAVE DRIFTS EWD
ACRS KY/TN INTO THE CNTRL APPLCHNS AND INTERACTS WITH ONSHORE MSTR
FEED INTERSECTING RETREATING Q-STNRY/WARM FRONT LIFTING NWD OVER
THE MID-ATLC. EXPECT LOW CLOUDS TO DEVELOP FROM SOUTH TO NORTH ON
SAT NGT IN SELY FLOW REGIME. TEMPS WILL BE WARMER ON FRIDAY WITH
MORE SUN.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
GUIDANCE CONTINUES TO TREND COOLER FOR SUNDAY WITH HIGHS IN THE
MID-UPPER 60S...AS MOIST ONSHORE FLOW STRENGTHENS /-2SD 850MB U
WIND ANOMALY IN GEFS/ AND BRINGS EXTENSIVE CLOUD COVER TO THE
REGION. MDL LI PROGS SHOW A CAD PATTERN IN THE LOW-LEVELS AS THE
WARM FRONT PIVOTS AND STALLS ALONG THE ALLEGHENY FRONT. WITH
STABLE CONDITIONS EXPECTED...CHANGED WX TYPE TO LGT RAIN AS
INSTABILITY SHOULD BE LOCATED WEST OF THE MTNS. FOCUS FOR PCPN
INTO MONDAY SHOULD REMAIN SOUTH OF PA OVER THE VA/NC IN CONJCT
WITH UPPER LEVEL WAVE AND MAX PWAT ANOM NR +2SD. HIGHEST POPS ARE
AGAIN OVER THE ERN 1/2 OF THE CWA AS SELY FLOW CONTS TO IMPINGE ON
SLOWLY RETREATING/DIFFUSE N-S WARM FRONT.
THE LG SCALE PATTERN IS FCST TO TURN DECIDEDLY MORE AMPLIFIED NEXT
WEEK...WITH THE MAIN SYNOPTIC FEATURE OF INTEREST BEING AN UPPER
LOW OVER THE NRN PLAINS/UPR MS VLY. H5 HGTS SHOULD RISE DOWNSTREAM
OF THIS SYSTEM...WITH CENTRAL PA LKLY BREAKING INTO THE WARM
SECTOR BY NEXT TUES AS THE PESKY WARM FRONT LIFTS NORTH INTO NEW
ENGLAND. THIS SHOULD AFFORD ONE OR TWO VERY WARM LATE SPRING DAYS
WITH HIGHS 75-80F. THERE IS A HIGH SPREAD BETWEEN THE GFS/ECMWF
CONCERNING THE POTENTIAL UPPER MIDWEST CUT-OFF. THEREFORE UTILIZED
A 50/50 BLEND OF THEIR RESPECTIVE MOS PRODUCTS FOR THE DAY 5-7
FCST.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
A SLOW-MOVING COLD FRONT MOVING WILL BE ACCOMPANIED BY A ROUND OF
SHRA...AND PERHAPS EVEN AN ISOLATED TSRA...EARLY THIS MORNING
ACROSS THE SOUTHERN PA AIRFIELDS. BASED ON LATEST RADAR
LOOP...MVFR CONDS WILL BE POSSIBLE BTWN 10Z-11Z AT JST/AOO...AFTER
WHICH A RETURN TO VFR CONDS APPEARS LIKELY. AT MDT/LNS...VSBY
REDUCTIONS IN SHRA/FOG COULD LAST UNTIL ARND 13Z.
BY LATE MORNING...THE FRONTAL BOUNDARY SHOULD SHIFT SOUTH OF
PA...RESULTING IN A HIGH DEGREE OF CONFIDENCE IN VFR CONDS ACROSS
THE ENTIRE STATE.
.OUTLOOK...
FRI-SUN...NO SIG WX EXPECTED.
MON...AM LOW CIGS POSSIBLE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
547 AM EDT THU MAY 16 2013
.SYNOPSIS...
AN WEST-EAST FRONTAL BOUNDARY ALONG THE MASON DIXON LINE EARLY
THIS MORNING WILL SINK SOUTHWARD INTO THE CENTRAL APPALACHIANS AND
BECOME QUASI-STATIONARY...PIVOTING TO A NW-SE ORIENTATION.
MEANWHILE...HIGH PRESSURE WILL MIGRATE EASTWARD ACROSS
SOUTHEASTERN CANADA WITH ONSHORE FLOW DEVELOPING ACROSS THE MID-
ATLANTIC REGION. THE FRONTAL BOUNDARY WILL SLOWLY PUSH BACK TO THE
NORTH AS A WARM FRONT OVER THE WEEKEND...AND LIFT NORTH OF THE
AREA BY EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
08Z SFC ANALYSIS PLACES QUASI-STATIONARY FRONT FROM SOUTHERN PA
WESTWARD TO SE IOWA. MOST CONVECTIVELY ACTIVE PORTION OF THIS FRONT
IS OVR SE OHIO/SW PA AT 08Z...THE RESULT OF LG SCALE FORCING AHEAD
OF SHORTWAVE MOVING OVR THE E GRT LKS. AS THIS FEATURE TRACKS
EAST...EXPECT THE BEST CHC OF SHRA AND A FEW TSRA TO SHIFT FROM THE
LAUREL HIGHLANDS TO THE LOWER SUSQ VALLEY BY 12Z. LATEST RAP AND
NAMPARA SIMULATED RADAR DATA BOTH INDICATE A SIMILAR SCENARIO
PLAYING OUT EARLY THIS AM.
SHORTWAVE WILL PASS EAST OF THE AREA BY LATE AM...WITH ENOUGH OF A
NWRLY FLOW BEHIND IT TO PUSH THE SFC FRONT JUST SOUTH OF THE MASON
DIXON LINE BY THIS AFTN. DIURNAL HEATING/DESTABILIZATION...COMBINED
WITH APPROACH OF NEXT SHORTWAVE OVR THE GRT LKS...SHOULD CAUSE A NEW
ROUND OF CONVECTION TO FIRE ALONG FRONT JUST SOUTH OF PA THIS AFTN.
WILL MAINTAIN ONLY A SLIGHT CHC ALONG OUR S TIER COUNTIES.
ALTHOUGH TODAY WILL DAWN MCLDY ACROSS SOUTHERN PA...A GOOD DEAL OF
SUNSHINE APPEARS LIKELY EVERYWHERE BY AFTN...AS WNW FLOW DRAWS DRIER
AIR INTO THE STATE. ENS MEAN 8H TEMPS OF ARND 13C SHOULD SUPPORT
HIGH TEMPS FROM THE M70S OVR THE ALLEGHENY PLATEAU...TO THE L80S IN
THE SUSQ VALLEY.
ALL MDL DATA INDICATING HIGH PRES RIDGE AND ASSOC DRY AIR MASS NOSES
SEWRD INTO PA TONIGHT...BRINGING MCLEAR SKIES AND LIGHT WINDS TO ALL
OF CENTRAL PA. THE DRIEST AIR...AS DEPICTED BY GEFS NEGATIVE PWAT
ANOMALIES...REMAIN ACROSS THE NORTHERN HALF OF THE STATE...WHERE
READINGS ARE LIKELY TO DIP INTO THE M/U30S. CAN/T RULE OUT SOME
PATCHY FROST UP THERE...BUT GROWING SEASON HAS NOT OFFICIALLY BEGUN
UP THERE...SO NO ADVISORY NEEDED.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
SFC HIGH PRES WILL SLIDE EWD FROM ONTARIO TO THE MARITIMES BY 12Z
SUNDAY...WITH ONSHORE FLOW DEVELOPING ACRS THE MID-ATLC STATES.
EXPECT SFC RIDGING AND LACK OF ANY SIGNIFICANT MID-UPPER LEVEL
FORCING TO LIMIT PCPN THROUGH MOST OF THE PERIOD. THE HIGHEST POPS
ARE OVER THE SERN ZONES SAT NGT AS AN UPPER LEVEL WAVE DRIFTS EWD
ACRS KY/TN INTO THE CNTRL APPLCHNS AND INTERACTS WITH ONSHORE MSTR
FEED INTERSECTING RETREATING Q-STNRY/WARM FRONT LIFTING NWD OVER
THE MID-ATLC. EXPECT LOW CLOUDS TO DEVELOP FROM SOUTH TO NORTH ON
SAT NGT IN SELY FLOW REGIME. TEMPS WILL BE WARMER ON FRIDAY WITH
MORE SUN.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
GUIDANCE CONTINUES TO TREND COOLER FOR SUNDAY WITH HIGHS IN THE
MID-UPPER 60S...AS MOIST ONSHORE FLOW STRENGTHENS /-2SD 850MB U
WIND ANOMALY IN GEFS/ AND BRINGS EXTENSIVE CLOUD COVER TO THE
REGION. MDL LI PROGS SHOW A CAD PATTERN IN THE LOW-LEVELS AS THE
WARM FRONT PIVOTS AND STALLS ALONG THE ALLEGHENY FRONT. WITH
STABLE CONDITIONS EXPECTED...CHANGED WX TYPE TO LGT RAIN AS
INSTABILITY SHOULD BE LOCATED WEST OF THE MTNS. FOCUS FOR PCPN
INTO MONDAY SHOULD REMAIN SOUTH OF PA OVER THE VA/NC IN CONJCT
WITH UPPER LEVEL WAVE AND MAX PWAT ANOM NR +2SD. HIGHEST POPS ARE
AGAIN OVER THE ERN 1/2 OF THE CWA AS SELY FLOW CONTS TO IMPINGE ON
SLOWLY RETREATING/DIFFUSE N-S WARM FRONT.
THE LG SCALE PATTERN IS FCST TO TURN DECIDEDLY MORE AMPLIFIED NEXT
WEEK...WITH THE MAIN SYNOPTIC FEATURE OF INTEREST BEING AN UPPER
LOW OVER THE NRN PLAINS/UPR MS VLY. H5 HGTS SHOULD RISE DOWNSTREAM
OF THIS SYSTEM...WITH CENTRAL PA LKLY BREAKING INTO THE WARM
SECTOR BY NEXT TUES AS THE PESKY WARM FRONT LIFTS NORTH INTO NEW
ENGLAND. THIS SHOULD AFFORD ONE OR TWO VERY WARM LATE SPRING DAYS
WITH HIGHS 75-80F. THERE IS A HIGH SPREAD BETWEEN THE GFS/ECMWF
CONCERNING THE POTENTIAL UPPER MIDWEST CUT-OFF. THEREFORE UTILIZED
A 50/50 BLEND OF THEIR RESPECTIVE MOS PRODUCTS FOR THE DAY 5-7
FCST.
&&
.AVIATION /09Z THURSDAY THROUGH MONDAY/...
A STALLED FRONTAL BOUNDARY LYING ACROSS SOUTHERN PA WILL PROVIDE
THE FOCUS FOR A FEW SHRA AND EVEN AN ISOLATED TSRA THIS MORNING.
05Z DWPT DEPRESSIONS AND NR TERM MDL DATA SUGGEST MDT AND LNS
WILL LIKELY SEE A BIT OF FOG IN THE 08Z-12Z TIME FRAME. MDL
GUIDANCE SUGGESTS VSBYS WILL GO NO LOWER THAN MVFR. HOWEVER...WOULD
NOT RULE OUT A BRIEF DIP TO IFR AT MDT/LNS...WHERE GROUND REMAINS
WET FROM YESTERDAY/S RAINFALL.
HIGHER DWPT DEPRESSIONS AT JST AND AOO INDICATE THEY WILL LIKELY
REMAIN VFR UNLESS A HEAVY SHRA/TSRA HAPPENS TO OCCUR BEFORE DAWN.
ANY EARLY FOG SHOULD LIFT SHORTLY AFTER SUNRISE. HOWEVER...WILL
STILL HAVE TO CONTEND WITH THE SLIGHT CHC OF A LATE AM SHRA/TSRA
ACROSS THE SOUTHERN AIRFIELDS. BY AFTN...THE FRONTAL BOUNDARY
SHOULD SHIFT SOUTH OF PA...RESULTING IN A HIGH DEGREE OF
CONFIDENCE IN VFR CONDS ACROSS THE ENTIRE STATE.
.OUTLOOK...
FRI-SUN...NO SIG WX EXPECTED.
MON...AM LOW CIGS POSSIBLE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
917 PM CDT FRI MAY 17 2013
.UPDATE...
NOT MUCH CHANGE IN THE FORECAST FOR THE TIME BEING. THUNDERSTORMS
HAVE FORMED OVER THE CENTRAL PORTION OF THE STATE AND ARE MOVING
NORTHEAST. STILL EXPECT SOME INCREASE IN COVERAGE AS THE LLJ GETS
CRANKED UP A BIT LATER TNT. HOWEVER QUESTIONABLE WHETHER THERE
WILL BE MUCH IN THE WAY OF SVR THE REST OF THE NIGHT. PERHAPS AN
ELEVATED HAILER OR TWO.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
THE MODELS ALL AGREE WELL AND CONTINUE TO BE VERY CONSISTENT AT
BRINGING THE UPPER LEVEL LOW PRESSURE TROUGH OUT OF THE SOUTHWEST
US THROUGH SUNDAY NIGHT AND CLOSING IT OFF. THUNDERSTORMS ARE
BEGINNING TO DEVELOP IN WESTERN SOUTH DAKOTA LATE THIS AFTERNOON
AND WILL CONTINUE TO DEVELOP AND MOVE EAST INTO CENTRAL AND NORTH
CENTRAL SOUTH DAKOTA THROUGH THE EVENING. THE HRRR MODEL SHOWS
THIS DEVELOPMENT VERY WELL. AS THE LLJ INCREASES INTO THE EVENING
HOURS...EXPECT THIS TREND TO CONTINUE. WITH INSTABILITY INCREASING
ALONG WITH DEEP LAYER SHEAR...SOME SEVERE STORMS ARE POSSIBLE
MAINLY WEST OF THE JAMES VALLEY TONIGHT. THIS FIRST WAVE WILL MOVE
THROUGH WITH MORE DEVELOPMENT EXPECTED SATURDAY AFTERNOON AND
EVENING ACROSS THE CWA. HIGH INSTABILITY WILL BUILD UP AGAIN
SATURDAY AFTERNOON AND EVENING ACROSS THE CWA WHILE ANOTHER SHORT
WAVE TROUGH KICKS OUT OF THE SOUTHWEST UPPER TROUGH. THIS
INTERACTION ALONG A GOOD LOW LEVEL SURFACE BOUNDARY/WARM FRONT ON
SATURDAY AFTERNOON AND EVENING WILL RESULT IN NUMEROUS SHOWERS AND
THUNDERSTORMS AGAIN. SEVERE STORMS LOOK LIKE A GOOD POSSIBILITY
ON SATURDAY AFTERNOON AND EVENING. AS THE MAIN UPPER LEVEL TROUGH
LIFTS INTO THE REGION SUNDAY AND SUNDAY NIGHT AND CLOSES
OFF...SHOWER AND THUNDERSTORM POSSIBILITIES WILL CONTINUE TO BE
VERY GOOD ACROSS ALL OF THE CWA. HEAVY RAIN WILL ALSO BE A THREAT
ACROSS THE CWA AS HIGH PRECIPITABLE WATERS WILL BE AVAILABLE FOR
STORMS.
.LONG TERM...MONDAY THROUGH FRIDAY
DECENT AGREEMENT EXISTS BETWEEN DETERMINISTIC GUIDANCE TO START
THINGS OFF WITH A NEARLY STATIONARY UPPER LOW OVER THE EASTERN
DAKOTAS/MINNESOTA. THIS FEATURE WILL DRIFT SLOWLY TO THE
EAST...WITH WRAP AROUND MOISTURE AND WEAK INSTABILITY LEADING TO
CONSTANT WIDESPREAD SHOWER ACTIVITY...WHICH WILL ALSO RESULT IN
TEMPERATURES BELOW NORMAL FOR MUCH OF THE EXTENDED. ONCE THE UPPER
LOW PUSHES EAST...A COL AREA FORMS OVERHEAD...WITH WEAK
SOUTHEASTERLY LOW LEVEL RETURN FLOW DEVELOPING FOR THE END OF THE
PERIOD...WITH MILDER TEMPERATURES AND LIKELY DRY CONDITIONS.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
OVERALL VFR CONDITIONS ARE EXPECTED OVERNIGHT...EXCEPT DURING
POTENTIAL THUNDERSTORMS. A CONVECTIVE COMPLEX IS EXPECTED TO FORM
LATER TNT AND THEN MOVE EAST ACROSS THE REGION. BRIEF IFR/MVFR
VSBYS/CIGS CAN BE EXPECTED WITH STORMS. WINDS WILL ALSO BE GUSTY
IN AND AROUND THUNDERSTORMS. AFTER PASSAGE OF THE STORMS THERE MAY
BE A DECK OF MVFR CLOUDS THAT SHOULD MIX OUT SATURDAY MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...MOHR
LONG TERM...CONNELLY
AVIATION...TDK
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
612 PM CDT FRI MAY 17 2013
.UPDATE...
AVIATION DISCUSSION HAS BEEN UPDATED.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
THE MODELS ALL AGREE WELL AND CONTINUE TO BE VERY CONSISTENT AT
BRINGING THE UPPER LEVEL LOW PRESSURE TROUGH OUT OF THE SOUTHWEST
US THROUGH SUNDAY NIGHT AND CLOSING IT OFF. THUNDERSTORMS ARE
BEGINNING TO DEVELOP IN WESTERN SOUTH DAKOTA LATE THIS AFTERNOON
AND WILL CONTINUE TO DEVELOP AND MOVE EAST INTO CENTRAL AND NORTH
CENTRAL SOUTH DAKOTA THROUGH THE EVENING. THE HRRR MODEL SHOWS
THIS DEVELOPMENT VERY WELL. AS THE LLJ INCREASES INTO THE EVENING
HOURS...EXPECT THIS TREND TO CONTINUE. WITH INSTABILITY INCREASING
ALONG WITH DEEP LAYER SHEAR...SOME SEVERE STORMS ARE POSSIBLE
MAINLY WEST OF THE JAMES VALLEY TONIGHT. THIS FIRST WAVE WILL MOVE
THROUGH WITH MORE DEVELOPMENT EXPECTED SATURDAY AFTERNOON AND
EVENING ACROSS THE CWA. HIGH INSTABILITY WILL BUILD UP AGAIN
SATURDAY AFTERNOON AND EVENING ACROSS THE CWA WHILE ANOTHER SHORT
WAVE TROUGH KICKS OUT OF THE SOUTHWEST UPPER TROUGH. THIS
INTERACTION ALONG A GOOD LOW LEVEL SURFACE BOUNDARY/WARM FRONT ON
SATURDAY AFTERNOON AND EVENING WILL RESULT IN NUMEROUS SHOWERS AND
THUNDERSTORMS AGAIN. SEVERE STORMS LOOK LIKE A GOOD POSSIBILITY
ON SATURDAY AFTERNOON AND EVENING. AS THE MAIN UPPER LEVEL TROUGH
LIFTS INTO THE REGION SUNDAY AND SUNDAY NIGHT AND CLOSES
OFF...SHOWER AND THUNDERSTORM POSSIBILITIES WILL CONTINUE TO BE
VERY GOOD ACROSS ALL OF THE CWA. HEAVY RAIN WILL ALSO BE A THREAT
ACROSS THE CWA AS HIGH PRECIPITABLE WATERS WILL BE AVAILABLE FOR
STORMS.
.LONG TERM...MONDAY THROUGH FRIDAY
DECENT AGREEMENT EXISTS BETWEEN DETERMINISTIC GUIDANCE TO START
THINGS OFF WITH A NEARLY STATIONARY UPPER LOW OVER THE EASTERN
DAKOTAS/MINNESOTA. THIS FEATURE WILL DRIFT SLOWLY TO THE
EAST...WITH WRAP AROUND MOISTURE AND WEAK INSTABILITY LEADING TO
CONSTANT WIDESPREAD SHOWER ACTIVITY...WHICH WILL ALSO RESULT IN
TEMPERATURES BELOW NORMAL FOR MUCH OF THE EXTENDED. ONCE THE UPPER
LOW PUSHES EAST...A COL AREA FORMS OVERHEAD...WITH WEAK
SOUTHEASTERLY LOW LEVEL RETURN FLOW DEVELOPING FOR THE END OF THE
PERIOD...WITH MILDER TEMPERATURES AND LIKELY DRY CONDITIONS.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
OVERALL VFR CONDITIONS ARE EXPECTED OVERNIGHT...EXCEPT DURING
POTENTIAL THUNDERSTORMS. A CONVECTIVE COMPLEX IS EXPECTED TO FORM
LATER TNT AND THEN MOVE EAST ACROSS THE REGION. BRIEF IFR/MVFR
VSBYS/CIGS CAN BE EXPECTED WITH STORMS. WINDS WILL ALSO BE GUSTY
IN AND AROUND THUNDERSTORMS. AFTER PASSAGE OF THE STORMS THERE MAY
BE A DECK OF MVFR CLOUDS THAT SHOULD MIX OUT SATURDAY MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...MOHR
LONG TERM...CONNELLY
AVIATION...TDK
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
913 PM CDT FRI MAY 17 2013
.AVIATION...
AN UPDATE FROM THE 00Z TAFS...LIGHT RAIN...MOSTLY EVAPORATING
BEFORE REACHING THE GROUND. THIS LIGHT RAIN WAS CAUSING WINDS TO
GUST UP TO 35 TO 40 MPH TO THE NORTHWEST OF THE METROPLEX...AND
WAS PRODUCING ISOLATED CLOUD TO GROUND LIGHTNING STRIKES OVER THE
SAME AREAS. AT THIS TIME IT LOOKS LIKE THE CORE OF THIS LIGHT
ANVIL CLOUD PRECIP WILL REMAIN NORTHWEST OF DFW AIRPORT...BUT WILL
BE WATCHING LOCAL AREA OBS CLOSELY FOR ANY DEVIATION FROM THIS
THINKING. WENT AHEAD AND AMENDED KAFW FOR VCTS AND GUSTY WINDS
FROM 02 TO 03Z DUE TO A RECORDED LIGHTNING STRIKE AROUND HASLET.
THE STORMS OUT WEST ARE BEGINNING TO DISSIPATE...SO THE THREAT FOR
GUSTY WINDS AND ANVIL CLOUD LIGHTNING STRIKES IS EXPECTED TO
DIMINISH THROUGH 04Z AS WELL.
CAVANAUGH
.../PREVIOUS AVIATION DISCUSSION/...
FOR THE 00Z TAFS...TIMING THE ONSET OF MVFR CIGS AND WATCHING FOR
ANY IMPACT TO TAF SITES FROM STORMS OUT WEST ARE THE PRIMARY
FORECAST CONCERNS.
AT THIS TIME...THE CAP ALOFT OVER AREA TAF SITES LOOKS TOO STRONG
TO ALLOW STORMS ONGOING NEAR SAN SABA AND GRAHAM TO MOVE EAST AND
DIRECTLY IMPACT THE INTERSTATE 35 CORRIDOR. STORMS WOULD LIKELY
DISSIPATE BEFORE MINERAL WELLS IF THEY STARTED TO MOVE EAST THIS
EVENING. WILL CONTINUE TO MONITOR THE IMPACT OF THESE STORMS ON
AREA TAF SITES HOWEVER AS ANVIL CLOUDS ARE THICK AND HAVE PRODUCED
LIGHTNING STRIKES AS FAR EAST AS DECATUR THIS EVENING. IF
LIGHTNING LOOKS TO IMPACT LOCAL AREA TAFS THIS EVENING MAY HAVE TO
ISSUE AN AIRPORT WEATHER WARNING FOR DFW AND AMEND TAFS TO MENTION
A THUNDERSTORM WITH NO RAIN. AT THIS TIME...THE PRESENCE OF SOME
HIGHER MID-LEVEL RH PRECLUDES A LARGER THREAT FOR HEAT BURSTS
ASSOCIATED WITH ANVIL CLOUD LIGHT PRECIPITATION.
DID NOT CHANGE THE TIMING OF THE ONSET OF MVFR STRATUS OVER AREA
TAF SITES AT THIS TIME. THE LAMP GUIDANCE IS THE MOST AGGRESSIVE
WITH THIS WITH LESS SUPPORT FROM RAP AND NAM FORECAST SOUNDINGS.
WILL MONITOR UPSTREAM STRATUS DEVELOPMENT TONIGHT AND MAY PULL
STRATUS FROM THE FORECAST BY 06Z IF THERE IS LITTLE UPSTREAM
DEVELOPMENT.
CAVANAUGH
&&
.SHORT TERM...
DRYLINE IS SHARPENING AND IS LOCATED FROM OLNEY TO BRECKENRIDGE
TO BRADY. THE DRYLINE HAS LIKELY REACHED ITS EASTERN MOST
LOCATION...AS A SURFACE LOW INDUCED BY VERY HOT TEMPERATURES IS
DEEPENING NORTH OF ABILENE. THIS HAS CAUSED SURFACE WINDS TO BEGIN
TO BACK TO THE SOUTHEAST ACROSS THE NW CWA...WHICH WILL PULL RICH
LOW LEVEL MOISTURE CHARACTERIZED BY DEWPOINTS NEAR 70 DEGREES BACK
TO THE WEST. THE COMBINATION OF TEMPS NEAR 100 WITH THESE DEWPOINTS
AND NEARLY DRY ADIABATIC LAPSE RATES FROM 500MB TO 850MB HAS
PRODUCED AN EXTREMELY UNSTABLE AIRMASS ACROSS OUR WESTERN ZONES
THIS AFTERNOON. LOCAL OBJECTIVE ANALYSIS IS DEPICTING SBCAPE
AROUND 3500 J/KG...AND POCKETS OF CAPE OVER 4000 J/KG WILL BE
POSSIBLE THROUGH EARLY EVENING. THE STRONG CAP THAT WAS EVIDENT ON
THE MORNING SOUNDING IS CLOSE TO BEING ERODED OVER THE WESTERN
ZONES...OR THE WESTERN 2 COLUMNS OF COUNTIES OF THE CWA. ALONG AND
EAST OF A BOWIE TO GRANBURY TO TEMPLE LINE...OBJECTIVE ANALYSIS
SHOWS CIN WELL ABOVE 200 J/KG AND VIS SATELLITE CONFIRMS THE
PRESENCE OF STRONG CAPPING IN CUMULUS FIELD. WITHOUT UPPER LEVEL
FORCING THIS CAP SHOULD REMAIN...WITH HEATING NOT SUFFICIENT ALONE
TO WEAKEN IT.
CONVECTIVE INITIATION IS NOW OCCURRING SOUTHWEST OF BROWNWOOD AND
CUMULUS IS ORGANIZING TO THE WEST OF BRECKENRIDGE. THIS IS TO
THE WEST OF THE DRY LINE...BUT THIS IS ACTUALLY THE FAVORED
LOCATION FOR UPWARD MESOSCALE FORCING ASSOCIATED WITH DRYLINES.
OFTEN THE LOW MOISTURE CONTENT BEHIND THE DRY LINE IS NOT
SUFFICIENT TO PRODUCE CUMULUS OR PRECIPITATION SO WE CANT SEE THE
LIFT...BUT THIS DRY LINE SEEMS TO HAVE MORE MOISTURE TO WORK WITH.
ONCE THE INFANT UPDRAFTS ARE ADVECTED TO THE MOIST SIDE OF THE DRY
LINE...THEY TAP INTO RICHER MOISTURE AND OFTEN GROW INTO CELLS
THAT RADAR CAN SEE. NEEDLESS TO SAY...CONVECTIVE INITIATION IS A
CERTAINTY AT THIS POINT...BUT COVERAGE OF STORMS WILL BE FAIRLY
LOW DUE TO WEAK UPPER LEVEL FORCING AND THE STRONG CAP. POPS WILL
RANGE FROM 20-40 PERCENT ACROSS THE WESTERN THIRD OF THE CWA.
DEEP LAYER SHEAR IS ON THE LOW SIDE OF WHAT IS TYPICALLY FOUND IN
SUPERCELL ENVIRONMENTS...BUT EXTREME INSTABILITY WILL LIKELY
COMPENSATE. STORM MOTION WILL START OUT EAST BUT AS SUPERCELLS
ORGANIZE AND MATURE THEY WILL LIKELY TURN TO THE SOUTH. THIS
SOUTHWARD MOVEMENT WILL ENHANCE LOW LEVEL STORM RELATIVE
HELICITY...WHICH MAY REACH 150-200 MS/S2 ACROSS THE NW ZONES WHERE
AN ISOLATED TORNADO THREAT IS GREATEST. HOWEVER THE MAIN THREAT
WILL BE GIANT HAIL AND DAMAGING WINDS GIVEN THE EXTREME INSTABILITY
AND LARGE DEWPOINT SPREADS. SPC HAS JUST ISSUED A SEVERE WATCH FOR
THE WESTERN ZONES...AND AGAIN DUE TO THE STRONG CAP AND SOUTHERLY
STORM MOTION BELIEVE ALL SEVERE ACTIVITY WILL REMAIN WEST OF THE
I-35 CORRIDOR. SOME LINGERING AND ELEVATED ACTIVITY MAY IMPACT THE
CENTRAL ZONES LATE TONIGHT...BUT THIS REMAINS A LOW PROBABILITY
AND KEPT POPS OUT OF THE FORECAST.
TR.92
&&
.LONG TERM...
A STRONG CAP WILL REMAIN IN PLACE ACROSS NORTH TEXAS THROUGH
MONDAY...SO THE CONVECTIVE FORECAST WILL HINGE ON WHETHER FORCING
FROM THE DRY LINE OR UPPER LEVEL SHORTWAVES WILL BE PRESENT. THE
DRYLINE WILL HEAD FARTHER WEST SATURDAY...AND ALTHOUGH A WELL
DEFINED SHORTWAVE MOVES ACROSS THE REGION...BELIEVE STORM
INITIATION WILL BE WELL NW OF THE CWA. A FEW OF THESE CELLS MAY
TRACK INTO THE NORTHWESTERN PARTS OF THE CWA SATURDAY
EVENING...BUT WILL KEEP POPS LOW AND AT 20 PERCENT. ON SUNDAY THE
DRY LINE WILL MIX EAST AGAIN AND FLIRT WITH THE NW CWA...AND HAVE
POPS A LITTLE HIGHER...BUT STILL PRIMARILY OVER THE NW ZONES IN
THE AFTERNOON. SINCE THE TAIL END OF THE PLAINS TROUGH WILL PASS
THROUGH THE NORTHERN ZONES SUNDAY NIGHT...CONVECTION MAY SURVIVE
PAST SUNSET AND TRACK ACROSS THE AREA NORTH OF I-20. EXPECT THE
SAME PATTERN ON MONDAY AND POPS ARE SIMILAR TO SUNDAYS. GIVEN THE
INSTABILITY AND SHEAR PROFILES SEVERE STORMS ARE POSSIBLE WITH ANY
ACTIVITY SATURDAY THROUGH MONDAY. FOR TEMPERATURES...SATURDAY WILL
BE THE WARMEST DAY WITH HIGHS IN THE 90S MOST AREAS...BUT WINDS
WILL INCREASE A BIT SUNDAY AND MONDAY WHICH SHOULD SHAVE A COUPLE
DEGREES...WITH HIGHS IN THE UPPER 80S EAST TO MID 90S WEST. LOWS
WILL REMAIN MUGGY AND IN THE LOW-MID 70S...WITH TONIGHT THE
COOLEST DUE TO FEWER CLOUDS AND LIGHTER WINDS.
ON TUESDAY ANOTHER LOBE OF ENERGY WILL ROTATE AROUND THE PLAINS
TROUGH AND HELP PROPEL A WEAK COLD FRONT SOUTH INTO THE AREA. THE
FRONT/DRYLINE COMBINATION WILL REACH THE NW CWA AND BECOME A FOCUS
FOR CONVECTION BY TUESDAY AFTERNOON. STRONG FORCING ASSOCIATED
WITH THE UPPER SHORTWAVE TROUGH WILL ENHANCE LIFT...AND EXPECT
SCATTERED CONVECTION TO OCCUR TUESDAY AFTERNOON AND WORK
SOUTHEAST ACROSS THE AREA. HAVE BUMPED POPS UP TO CHANCE AS THIS
WILL BE THE BEST DAY FOR RAIN CHANCES. AGAIN...THERE IS A SEVERE
WEATHER THREAT WITH THIS CONVECTION AS WELL.
THE FRONT WILL NOT BE VERY STRONG...AND WINDS MAY NOT SPEND MUCH
OR ANY TIME FROM THE NORTH...BUT THE AXIS OF BEST MOISTURE AND
INSTABILITY SHOULD GET PUSHED SOUTHEAST OF THE AREA. WILL KEEP A
SLIGHT CHANCE OF CONVECTION WEDNESDAY...BUT THIS ACTIVITY IS NOT
EXPECTED TO BE VERY SIGNIFICANT. TEMPS WILL BE A LITTLE COOLER AS
HEIGHTS LOWER...AND THE SLIGHTLY DRIER AIR WILL HELP LOWS FALL TO
NEAR NORMAL. HAVE KEPT THE REMAINDER OF THE FORECAST DRY AS UPPER
LEVEL RIDGING BUILDS INTO THE AREA...WHICH IS WELL AGREED UPON BY
EXTENDED GUIDANCE.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 92 72 90 72 / 10 5 5 10 20
WACO, TX 70 92 72 91 73 / 10 5 5 10 10
PARIS, TX 69 88 70 87 68 / 10 10 5 5 20
DENTON, TX 70 93 72 90 72 / 10 10 10 10 30
MCKINNEY, TX 69 90 71 89 71 / 10 5 5 5 20
DALLAS, TX 73 93 74 91 74 / 10 5 5 10 20
TERRELL, TX 69 90 70 91 71 / 10 5 5 5 10
CORSICANA, TX 70 90 70 89 73 / 10 5 5 5 10
TEMPLE, TX 69 92 71 91 72 / 20 10 5 10 10
MINERAL WELLS, TX 71 96 69 94 70 / 20 10 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
641 PM CDT FRI MAY 17 2013
.AVIATION...
FOR THE 00Z TAFS...TIMING THE ONSET OF MVFR CIGS AND WATCHING FOR
ANY IMPACT TO TAF SITES FROM STORMS OUT WEST ARE THE PRIMARY
FORECAST CONCERNS.
AT THIS TIME...THE CAP ALOFT OVER AREA TAF SITES LOOKS TOO STRONG
TO ALLOW STORMS ONGOING NEAR SAN SABA AND GRAHAM TO MOVE EAST AND
DIRECTLY IMPACT THE INTERSTATE 35 CORRIDOR. STORMS WOULD LIKELY
DISSIPATE BEFORE MINERAL WELLS IF THEY STARTED TO MOVE EAST THIS
EVENING. WILL CONTINUE TO MONITOR THE IMPACT OF THESE STORMS ON
AREA TAF SITES HOWEVER AS ANVIL CLOUDS ARE THICK AND HAVE PRODUCED
LIGHTNING STRIKES AS FAR EAST AS DECATUR THIS EVENING. IF
LIGHTNING LOOKS TO IMPACT LOCAL AREA TAFS THIS EVENING MAY HAVE TO
ISSUE AN AIRPORT WEATHER WARNING FOR DFW AND AMEND TAFS TO MENTION
A THUNDERSTORM WITH NO RAIN. AT THIS TIME...THE PRESENCE OF SOME
HIGHER MID-LEVEL RH PRECLUDES A LARGER THREAT FOR HEAT BURSTS
ASSOCIATED WITH ANVIL CLOUD LIGHT PRECIPITATION.
DID NOT CHANGE THE TIMING OF THE ONSET OF MVFR STRATUS OVER AREA
TAF SITES AT THIS TIME. THE LAMP GUIDANCE IS THE MOST AGGRESSIVE
WITH THIS WITH LESS SUPPORT FROM RAP AND NAM FORECAST SOUNDINGS.
WILL MONITOR UPSTREAM STRATUS DEVELOPMENT TONIGHT AND MAY PULL
STRATUS FROM THE FORECAST BY 06Z IF THERE IS LITTLE UPSTREAM
DEVELOPMENT.
CAVANAUGH
&&
.SHORT TERM...
DRYLINE IS SHARPENING AND IS LOCATED FROM OLNEY TO BRECKENRIDGE
TO BRADY. THE DRYLINE HAS LIKELY REACHED ITS EASTERN MOST
LOCATION...AS A SURFACE LOW INDUCED BY VERY HOT TEMPERATURES IS
DEEPENING NORTH OF ABILENE. THIS HAS CAUSED SURFACE WINDS TO BEGIN
TO BACK TO THE SOUTHEAST ACROSS THE NW CWA...WHICH WILL PULL RICH
LOW LEVEL MOISTURE CHARACTERIZED BY DEWPOINTS NEAR 70 DEGREES BACK
TO THE WEST. THE COMBINATION OF TEMPS NEAR 100 WITH THESE DEWPOINTS
AND NEARLY DRY ADIABATIC LAPSE RATES FROM 500MB TO 850MB HAS
PRODUCED AN EXTREMELY UNSTABLE AIRMASS ACROSS OUR WESTERN ZONES
THIS AFTERNOON. LOCAL OBJECTIVE ANALYSIS IS DEPICTING SBCAPE
AROUND 3500 J/KG...AND POCKETS OF CAPE OVER 4000 J/KG WILL BE
POSSIBLE THROUGH EARLY EVENING. THE STRONG CAP THAT WAS EVIDENT ON
THE MORNING SOUNDING IS CLOSE TO BEING ERODED OVER THE WESTERN
ZONES...OR THE WESTERN 2 COLUMNS OF COUNTIES OF THE CWA. ALONG AND
EAST OF A BOWIE TO GRANBURY TO TEMPLE LINE...OBJECTIVE ANALYSIS
SHOWS CIN WELL ABOVE 200 J/KG AND VIS SATELLITE CONFIRMS THE
PRESENCE OF STRONG CAPPING IN CUMULUS FIELD. WITHOUT UPPER LEVEL
FORCING THIS CAP SHOULD REMAIN...WITH HEATING NOT SUFFICIENT ALONE
TO WEAKEN IT.
CONVECTIVE INITIATION IS NOW OCCURRING SOUTHWEST OF BROWNWOOD AND
CUMULUS IS ORGANIZING TO THE WEST OF BRECKENRIDGE. THIS IS TO
THE WEST OF THE DRY LINE...BUT THIS IS ACTUALLY THE FAVORED
LOCATION FOR UPWARD MESOSCALE FORCING ASSOCIATED WITH DRYLINES.
OFTEN THE LOW MOISTURE CONTENT BEHIND THE DRY LINE IS NOT
SUFFICIENT TO PRODUCE CUMULUS OR PRECIPITATION SO WE CANT SEE THE
LIFT...BUT THIS DRY LINE SEEMS TO HAVE MORE MOISTURE TO WORK WITH.
ONCE THE INFANT UPDRAFTS ARE ADVECTED TO THE MOIST SIDE OF THE DRY
LINE...THEY TAP INTO RICHER MOISTURE AND OFTEN GROW INTO CELLS
THAT RADAR CAN SEE. NEEDLESS TO SAY...CONVECTIVE INITIATION IS A
CERTAINTY AT THIS POINT...BUT COVERAGE OF STORMS WILL BE FAIRLY
LOW DUE TO WEAK UPPER LEVEL FORCING AND THE STRONG CAP. POPS WILL
RANGE FROM 20-40 PERCENT ACROSS THE WESTERN THIRD OF THE CWA.
DEEP LAYER SHEAR IS ON THE LOW SIDE OF WHAT IS TYPICALLY FOUND IN
SUPERCELL ENVIRONMENTS...BUT EXTREME INSTABILITY WILL LIKELY
COMPENSATE. STORM MOTION WILL START OUT EAST BUT AS SUPERCELLS
ORGANIZE AND MATURE THEY WILL LIKELY TURN TO THE SOUTH. THIS
SOUTHWARD MOVEMENT WILL ENHANCE LOW LEVEL STORM RELATIVE
HELICITY...WHICH MAY REACH 150-200 MS/S2 ACROSS THE NW ZONES WHERE
AN ISOLATED TORNADO THREAT IS GREATEST. HOWEVER THE MAIN THREAT
WILL BE GIANT HAIL AND DAMAGING WINDS GIVEN THE EXTREME INSTABILITY
AND LARGE DEWPOINT SPREADS. SPC HAS JUST ISSUED A SEVERE WATCH FOR
THE WESTERN ZONES...AND AGAIN DUE TO THE STRONG CAP AND SOUTHERLY
STORM MOTION BELIEVE ALL SEVERE ACTIVITY WILL REMAIN WEST OF THE
I-35 CORRIDOR. SOME LINGERING AND ELEVATED ACTIVITY MAY IMPACT THE
CENTRAL ZONES LATE TONIGHT...BUT THIS REMAINS A LOW PROBABILITY
AND KEPT POPS OUT OF THE FORECAST.
TR.92
&&
.LONG TERM...
A STRONG CAP WILL REMAIN IN PLACE ACROSS NORTH TEXAS THROUGH
MONDAY...SO THE CONVECTIVE FORECAST WILL HINGE ON WHETHER FORCING
FROM THE DRY LINE OR UPPER LEVEL SHORTWAVES WILL BE PRESENT. THE
DRYLINE WILL HEAD FARTHER WEST SATURDAY...AND ALTHOUGH A WELL
DEFINED SHORTWAVE MOVES ACROSS THE REGION...BELIEVE STORM
INITIATION WILL BE WELL NW OF THE CWA. A FEW OF THESE CELLS MAY
TRACK INTO THE NORTHWESTERN PARTS OF THE CWA SATURDAY
EVENING...BUT WILL KEEP POPS LOW AND AT 20 PERCENT. ON SUNDAY THE
DRY LINE WILL MIX EAST AGAIN AND FLIRT WITH THE NW CWA...AND HAVE
POPS A LITTLE HIGHER...BUT STILL PRIMARILY OVER THE NW ZONES IN
THE AFTERNOON. SINCE THE TAIL END OF THE PLAINS TROUGH WILL PASS
THROUGH THE NORTHERN ZONES SUNDAY NIGHT...CONVECTION MAY SURVIVE
PAST SUNSET AND TRACK ACROSS THE AREA NORTH OF I-20. EXPECT THE
SAME PATTERN ON MONDAY AND POPS ARE SIMILAR TO SUNDAYS. GIVEN THE
INSTABILITY AND SHEAR PROFILES SEVERE STORMS ARE POSSIBLE WITH ANY
ACTIVITY SATURDAY THROUGH MONDAY. FOR TEMPERATURES...SATURDAY WILL
BE THE WARMEST DAY WITH HIGHS IN THE 90S MOST AREAS...BUT WINDS
WILL INCREASE A BIT SUNDAY AND MONDAY WHICH SHOULD SHAVE A COUPLE
DEGREES...WITH HIGHS IN THE UPPER 80S EAST TO MID 90S WEST. LOWS
WILL REMAIN MUGGY AND IN THE LOW-MID 70S...WITH TONIGHT THE
COOLEST DUE TO FEWER CLOUDS AND LIGHTER WINDS.
ON TUESDAY ANOTHER LOBE OF ENERGY WILL ROTATE AROUND THE PLAINS
TROUGH AND HELP PROPEL A WEAK COLD FRONT SOUTH INTO THE AREA. THE
FRONT/DRYLINE COMBINATION WILL REACH THE NW CWA AND BECOME A FOCUS
FOR CONVECTION BY TUESDAY AFTERNOON. STRONG FORCING ASSOCIATED
WITH THE UPPER SHORTWAVE TROUGH WILL ENHANCE LIFT...AND EXPECT
SCATTERED CONVECTION TO OCCUR TUESDAY AFTERNOON AND WORK
SOUTHEAST ACROSS THE AREA. HAVE BUMPED POPS UP TO CHANCE AS THIS
WILL BE THE BEST DAY FOR RAIN CHANCES. AGAIN...THERE IS A SEVERE
WEATHER THREAT WITH THIS CONVECTION AS WELL.
THE FRONT WILL NOT BE VERY STRONG...AND WINDS MAY NOT SPEND MUCH
OR ANY TIME FROM THE NORTH...BUT THE AXIS OF BEST MOISTURE AND
INSTABILITY SHOULD GET PUSHED SOUTHEAST OF THE AREA. WILL KEEP A
SLIGHT CHANCE OF CONVECTION WEDNESDAY...BUT THIS ACTIVITY IS NOT
EXPECTED TO BE VERY SIGNIFICANT. TEMPS WILL BE A LITTLE COOLER AS
HEIGHTS LOWER...AND THE SLIGHTLY DRIER AIR WILL HELP LOWS FALL TO
NEAR NORMAL. HAVE KEPT THE REMAINDER OF THE FORECAST DRY AS UPPER
LEVEL RIDGING BUILDS INTO THE AREA...WHICH IS WELL AGREED UPON BY
EXTENDED GUIDANCE.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 92 72 90 72 / 10 5 5 10 20
WACO, TX 70 92 72 91 73 / 10 5 5 10 10
PARIS, TX 69 88 70 87 68 / 10 10 5 5 20
DENTON, TX 70 93 72 90 72 / 10 10 10 10 30
MCKINNEY, TX 69 90 71 89 71 / 10 5 5 5 20
DALLAS, TX 73 93 74 91 74 / 10 5 5 10 20
TERRELL, TX 69 90 70 91 71 / 10 5 5 5 10
CORSICANA, TX 70 90 70 89 73 / 10 5 5 5 10
TEMPLE, TX 69 92 71 91 72 / 20 10 5 10 10
MINERAL WELLS, TX 71 96 69 94 70 / 20 10 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1148 PM CDT WED MAY 15 2013
.UPDATE...
UPDATED FORECAST FOR SEVERE THUNDERSTORM WATCH 162
&&
.DISCUSSION...
BOW ECHO OVER C TX SHOULD PROGRESS TOWARDS SE TX TONIGHT INTO THE
EARLY MORNING HOURS. THINK MOMENTUM FROM SYSTEM SHOULD CARRY IT
INTO KCLL/KUTS AREA AROUND 6-8Z. STORM ENVIRONMENT STILL NOT AS
ROBUST AS C TX WITH LIMITED CAPE AND CIN FROM OVERNIGHT
STABILIZATION. MAIN THREAT FROM THE SQUALL LINE WILL BE STRAIGHT
LINE WINDS WITH HAIL AS SECONDARY THREAT. UPDATED FORECAST HAS
BEEN SENT.
39
&&
.PREV DISCUSSION... /ISSUED 934 PM CDT WED MAY 15 2013/
UPDATE...
EVENING FORECAST UPDATE.
DISCUSSION...
MONITORING SEVERE WEATHER OUTBREAK OVER N C TX WITH GREAT
INTEREST. UNFORTUNATELY SAD THAT THERE HAS BEEN SIGNIFICANT
DAMAMGE IN AREAS SW OF DFW METROPLEX. MAIN CONCERN IS THAT THE 12Z
WRF-ARW AND RECENT RUNS OF HRRR TRY TO BRING A LINE OF STORMS INTO
THE NORTHERN PORTIONS OF SE TX LATE TONIGHT INTO TOMORROW MORNING.
FOR NOW DO NOT SEE A LINE OF STORMS FORMING YET AND WILL WATCH FOR
THIS TO HAPPEN. THINK 30 POPS FOR NOW LOOKS ON TRACK FOR NOW.
ENVIRONMENT IS A LOT LESS FAVORABLE FOR SEVERE WEATHER WITH MOST
OF THE AREA CAPPED AND WITH LESS THAN 1000 J/KG OF CAPE. SUSPECT
THAT STORMS WILL WEAKEN AS THEY MOVE TOWARDS SE TX. THAT IS IF A
LINE OF STORMS CAN FORM WHICH GIVEN THE STORM MODE OF ISO
SUPERCELLS...NOT SURE THAT WILL HAPPEN. RIGHT NOW AREAS FROM
COLLEGE STATION TO CROCKETT ARE ON THE EDGE OF BETTER SUPERCELL
ENVIRONMENT BUT IT IS A FINE LINE. POSSIBLE SPC MAY WATCH THESE
AREAS LATER THIS EVENING BUT REMAINS TO BE SEEN SINCE THE STORM
ENVIRONMENT IS NOT AS FAVORABLE. UPDATED FORECAST HAS BEEN SENT.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 68 85 71 89 72 / 50 20 10 10 10
HOUSTON (IAH) 69 84 71 88 71 / 30 20 10 10 10
GALVESTON (GLS) 72 79 73 78 74 / 20 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 4 AM CDT THURSDAY FOR
THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA
SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND
TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...39
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
331 PM CDT THU MAY 16 2013
.VERY SHORT TERM...TONIGHT AND FRIDAY. FORECAST CONFIDENCE...
MEDIUM
A SLIGHT CHANCE FOR SHOWERS ACROSS THE NORTHWEST FORECAST AREA WAS
HELD ONTO THROUGH EARLY EVENING. CURRENTLY...THERE IS A LOT OF
CUMULUS DEVELOPMENT IN THE NORTHEAST...BUT NO SIGNS OF
PRECIPITATION. MAY HAVE TO REMOVE THESE POPS BY LATE AFTERNOON IF
LACK OF DEVELOPMENT PERSISTS. MODELS HAVE BACKED OFF AS WELL...SO
LOOKING LESS LIKELY BY THE HOUR. DEW POINT DEPRESSIONS ARE ON THE
ORDER OF 40 DEGREES AT THE MOMENT ACROSS THE NORTHWEST...SO THE DRY
AIR IS LIKELY CONTRIBUTING TO THE LACK OF DEVELOPMENT.
SHOULD BE DRY THEN THROUGH THE MAJORITY OF THE NIGHT. THE HRRR TRIES
TO SNEAK SOME ACTIVITY INTO THE SW A BIT EARLIER THAN OTHER
MODELS...BUT GENERALLY HELD OFF ON POPS UNTIL EARLY TOMORROW
MORNING. AS THE LAKE AIR MASS CONTINUES TO PUSH INLAND UNDER EASTERLY
WINDS...LOWS TONIGHT SHOULD NEAR NORMAL VALUES...MAINLY IN THE UPPER
40S TO LOW 50S.
WILL HAVE A BAROCLINIC ZONE STRETCHED NORTHWEST TO SOUTHEAST ACROSS
THE FORECAST AREA ON FRIDAY...WHILE A WEAK SHORTWAVE APPROACHES THE
AREA. THESE FEATURES WILL LIKELY COMBINE TO KICK OFF SHOWER AND
THUNDERSTORM ACTIVITY TOMORROW...PARTICULARLY ACROSS THE WEST AND
SOUTHWEST TOWARD THE MILDER AIR. A COOL AND STABLE AIR MASS OFF THE
LAKE WILL LIKE INHIBIT DEVELOPMENT IN THE EAST...SO KEPT POPS LOW.
WILL SEE GOOD SPREAD IN HIGH TEMPS TOMORROW...WITH HIGHS LIKELY NOT
GETTING OUT OF THE 50S ALONG THE LAKESHORE UNDER ONSHORE WINDS...TO
THE LOW 70S IN THE SOUTHWEST.
.SHORT TERM...FRIDAY NIGHT THROUGH SUNDAY.
FRIDAY NIGHT...FORECAST CONFIDENCE
MODELS TAKE PRECIPITATION MAXIMA AT THE START OF THE PERIOD TO THE
NORTH AND SOUTH OF THE FORECAST AREA WITH DEPARTING SHORT WAVES.
LINGERING Q-VECTOR CONVERGENCE SUPPORT A GRADIENT OF CHANCE
POPS...WITH THE HIGHER CHANCES NORTH...DIMINISHING AFTER 06Z
SATURDAY. WITH WARM FRONT JUST PUSHING INTO THE FAR SW...WILL SEE A
NEARLY 10-DEGREE DIFFERENCE WITH OVERNIGHT LOWS...WITH UPPER 40S IN
THE NORTHEAST AND UPPER 50S IN THE FAR SW.
SATURDAY...FORECAST CONFIDENCE MEDIUM.
ENOUGH INSTABILITY AS DAYTIME HEATING/MIXING KICK IN...AND LOW-LEVEL
CONVERGENCE AS WARM FRONT STALLS AND BECOMES A STATIONARY FRONT
THROUGH THE MIDDLE PORTIONS OF THE CWA...TO WARRANT LOW-END POPS.
SOME OF THE HIGHER INSTABILITY IS PREDICATED ON HIGHER THAN
EXPECTED MODEL SURFACE DEW POINTS...A RECENT PROBLEM ON THE
MODELS...SO HOLDING TO ONLY SLIGHT CHANCE POPS APPEARS
APPROPRIATE. WILL SEE A STRONG TEMPERATURE CONTRAST ACROSS THE
STATIONARY BOUNDARY WITH MID-UPPER 70S IN THE SW 1/2....AND UPPER
60S TO LOW 70S NE HALF.
SATURDAY NIGHT...FORECAST CONFIDENCE HIGH.
RIDGING AHEAD OF DEEPENING WAVE KEEPS AREA DRY. EASTERLY WINDS BRING
UPPER 40S-LOW 50S ALONG THE KETTLE MORAINE AND EAST...AND IN THE MID
TO UPPER 50S TO THE WEST WITH LOW 60S IN THE SOUTHWEST.
.LONG TERM...
THIS PERIOD DOMINATED BY IMPACT OF CLOSED...NEARLY-STACKED LOW AS IT
MOVES/FILLS OVER THE UPPER MIDWEST. CHANCES FOR THUNDER EACH PERIOD
FROM SUNDAY NIGHT INTO WEDNESDAY WITH LOBES OF VORTICITY ROTATING
AROUND CENTRAL CIRCULATION PROVIDING LIFT TO A WARM...MOIST UNSTABLE
AIR MASS FEEDING INTO THE REGION ON SRLY FLOW AHEAD OF TROUGH. CIPS
ANALOGS HAS INCREASING PROBABILITIES MOVING INTO SW WI MONDAY/MONDAY
NIGHT...WITH SPC DAY 4-8 COMPOSITE OUTLOOK BRUSHING SOUTHWEST
WISCONSIN ON DAYS 4 AND 5.
SOME QUESTION AS TO EVOLUTION OF SYSTEM...12Z ECMWF SLOWLY OPENS
THE SYSTEM AND MOVES IT SOUTHEAST AS IT PHASES WITH A SHORT WAVE
DROPPING THROUGH EASTERN ONTARIO/WESTERN QUEBEC...WHILE THE GFS
HAS THE LOW FILL AND SHEAR OUT OVER THE WESTERN GREAT LAKES.
EITHER SOLUTION KEEPS THE MAJORITY OF THE EXTENDED WITH PCPN
CHANCES UNTIL THE REMNANT LOW/TROUGH DROPS SOUTHEAST BY
THURSDAY/THURSDAY NIGHT. SHOULD SEE MODE CHANGE FROM THUNDER TO
RAIN SHOWERS WEDNESDAY NIGHT AND THURSDAY AS MID-LEVEL OCCLUSION
PUSHES THE MORE UNSTABLE AIR MASS TO THE EAST.
&&
.AVIATION/00Z TAFS/...
VFR CONDITIONS WILL PERSIST THROUGH FRIDAY. SHOULD SEE MAINLY DRY
WEATHER THIS EVENING AND OVERNIGHT. THERE WILL BE A CHANCE FOR
SHOWERS AND STORMS FRIDAY...THE BEST CHANCE IN THE LATE MORNING AND
AFTERNOON WEST OF A FOND DU LAC TO JANESVILLE LINE.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TONIGHT/FRIDAY AND AVIATION/MARINE...DDV
FRIDAY NIGHT THROUGH THURSDAY...REM
AREA FORECAST DISCUSSION
NWS MIAMI FL
300 AM EDT SAT MAY 18 2013
.SHORT TERM (TODAY-MONDAY)...
ANOTHER WARM AND PLEASANT WEEKEND IS ANTICIPATED ACROSS SOUTH
FLORIDA WITH TEMPERATURES REMAINING AROUND TO SLIGHTLY ABOVE NORMAL
EACH DAY. THE LATEST NUMERICAL GUIDANCE REMAINS PERSISTENT AND IN
GOOD AGREEMENT DEPICTING AN UPPER RIDGE BUILDING EASTWARD OVER THE
MS VALLEY TRAILING A SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHWEST
FLOW ALOFT. AS THIS SHORTWAVE ADVANCES E-SEWD OVER THE
STATE...UPPER HEIGHTS WILL SLIGHTLY FALL OVER THE STATE BY THE END
OF THE DAY. MODEL SOUNDINGS ACROSS THE NORTHERN AND INTERIOR
LOCATIONS OF THE LOCAL AREA REFLECT THIS AND INDICATE SOME MID-
LEVEL COOLING BY 00Z (H5 TEMPS AROUND -11C) WITH MID-LEVEL LAPSE
RATES STEEPENING (-6 TO -7 C/KM). THIS COMBINED WITH LIGHT
SOUTHEAST LOW-LEVEL FLOW...A SUFFICIENT AMOUNT OF LOW-LEVEL
MOISTURE AND DAYTIME HEATING WILL SUPPORT A FEW STORMS LATER TODAY
THROUGH THE LATE AFTERNOON/EARLY EVENING TIME FRAME. THE BEST
CHANCE FOR THIS ACTIVITY WILL BE ACROSS THE INTERIOR AND NORTHERN
LOCATIONS. THE FSU GRIDDED LIGHTNING PROBABILITY DATABASE AND THE
LATEST GRIDDED MOS THUNDERSTORM PROBABILITIES ARE GENERALLY
OUTPUTTING 20-40 PERCENT CHANCES OVER THESE INTERIOR LOCATIONS
THROUGH THIS TIME. THE MAIN LIMITING FACTORS FOR WIDESPREAD DEEP
MOIST CONVECTION WILL BE A PERSISTENT MID-LEVEL CAP BETWEEN 650 MB
AND 700 MB ALONG WITH PLENTY OF MID-LEVEL DRY AIR ENTRAINING INTO
ANY DEVELOPING CELLS. ANY STORM THAT DOES DEVELOP COULD BECOME
STRONG WITH THE MAIN IMPACTS BEING SMALL HAIL AND DAMAGING
STRAIGHT-LINE WINDS (40-55 MPH). THE LATEST HI-RES MODEL
REFLECTIVITIES BETWEEN THE WRF AND NAM GENERALLY LINE UP WELL AND
DEPICT SOME ACTIVITY INITIATING INLAND AND TOWARD THE NORTH AROUND
LAKE OKEECHOBEE THROUGH THE LATE AFTERNOON AND EARLY EVENING
PERIODS. SIMILAR CONDITIONS WILL PERSIST WITH THE EASTERLY LOW-
LEVEL FAVORING INTERIOR AFTERNOON ACTIVITY AGAIN ON SUNDAY AND
MONDAY. OVERNIGHT AND THROUGH THE EARLY MORNING HOURS EACH
DAY...SHOWERS AND A FEW STORMS ACROSS THE ATLANTIC WATERS AND THE
EAST COAST LOCATIONS WILL REMAIN POSSIBLE DUE TO THE CONFLUENT
BOUNDARIES SETTING UP DOWNSTREAM OF THE BAHAMAS AND RADIATIONAL
CLOUD-TOP COOLING.
.LONG TERM (MONDAY NIGHT-FRIDAY)...
THE GFS/ENSEMBLE MEAN AND ECMWF GENERALLY REMAIN IN GOOD AGREEMENT
THROUGH THE EXTENDED PERIOD AND INDICATE A PERSISTENT UPPER TROUGH
CONTINUING TO INFLUENCE THE LOCAL AREA. ADDITIONALLY...A SURGE OF
DEEP LAYER MOISTURE LATER IN THE WEEK ASSOCIATED WITH A WEAK SURFACE
TROUGH EMBEDDED IN THE EASTERLY FLOW COMBINED WITH THE UPPER TROUGH
COULD LEAD TO MORE WIDESPREAD RAINFALL ACTIVITY EACH DAY WEDNESDAY
THROUGH FRIDAY. HOWEVER...WE WILL CONTINUE TO MONITOR LATER MODEL
TRENDS FOR CONSISTENCY OVER THE WEEKEND BEFORE INCREASING THE
RAINFALL CHANCES. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL EACH DAY.
&&
.AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS WILL CONTINUE ACROSS THE COASTAL
ATLANTIC WATERS THROUGH THE EARLY MORNING HOURS. LATEST HRRR AND
LOCAL MODELS INCREASE COVERAGE OF SHOWERS THROUGH THE MORNING AND
PUSH THEM INLAND ACROSS THE EAST COAST METRO AREAS UNDER WEAK
EASTERLY FLOW. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
&&
.MARINE...
LIGHT TO MODERATE EAST AND SOUTHEAST WINDS WILL CONTINUE THROUGH
MUCH OF THE FORECAST PERIOD AS HIGH PRESSURE REMAINS IN CONTROL
NORTHEAST OF THE MARINE AREA. ISOLATED OVERNIGHT AND EARLY MORNING
SHOWERS WILL REMAIN POSSIBLE EACH DAY ACROSS THE ATLANTIC WATERS.
&&
.FIRE WEATHER...
SOUTHEAST LOW-LEVEL WINDS ALONG WITH PLENTY OF LOW-LEVEL MOISTURE
WILL PERSIST THROUGH THE WEEKEND. MOST OF THE SHOWERS AND STORMS
THAT DEVELOP WILL BE FOCUSED ALONG THE EAST COAST THROUGH THE EARLY
MORNING HOURS AND ACROSS THE INTERIOR LOCATIONS THROUGH THE
AFTERNOON/EVENING PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 74 85 74 / 20 20 20 20
FORT LAUDERDALE 85 76 86 76 / 20 20 20 20
MIAMI 87 75 87 75 / 20 20 20 20
NAPLES 89 71 89 71 / 20 20 30 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
438 AM EDT SAT MAY 18 2013
.SHORT TERM /TODAY THROUGH SUNDAY/...
COMPLEX AND DIFFICULT FORECAST THE NEXT 24 TO 36 HOURS. SLOW MOVING
AND WEAK UPPER LEVEL LOW NOTED IN WATER VAPOR OVER CENTRAL TN
RESPONSIBLE FOR SHOWERS AND A FEW STORMS MOVING INTO WESTERN GA NOW
THROUGH SAT AM. MODELS CONTINUE TO KEEP THE REGION IN A GENERAL
NORTHWEST FLOW PATTERN THROUGH SUNDAY WITH WEAK DISTURBANCES MOVING
SOUTHEAST ON THE SOUTHWEST SIDE OF THE WEAK UPPER LOW. ALL OF THE
MODELS AGREE ON CHANCE TO LIKELY POPS FOR A PORTION OF THE AREA BUT
DISAGREE ON EXACT LOCATION AND TIMING...MOST LIKELY DUE TO
DIFFICULTIES RESOLVING THESE FEATURES. FOR TODAY...BIG QUESTION
WITH THIS ONGOING ACTIVITY IS HOW MUCH CLOUD DEBRIS WILL REMAIN AND
HINDER OR DELAY ANY DAYTIME HEATING ACROSS GA AND THE ONSET OF
THUNDERSTORM DEVELOPMENT. HRRR AND HIGH RES WRF CONTINUE TO SHOW
SHOWERS THROUGH MORNING WITH MORE SCATTERED CONVECTION DEVELOPING
THIS AFTERNOON. AS A RESULT...HAVE OPTED TO MAINTAIN SOME
CONSISTENCY WITH THE PREVIOUS FORECAST WHICH SHOWS HIGHEST POPS
ACROSS NORTHERN GA THROUGH SAT AND LESSER POPS ACROSS THE SOUTHERN TIER.
WILL HAVE TO WATCH THE SOUTHERN TIER OF COUNTIES AS DIFFERENTIAL
HEATING MAY HAVE A BIGGER THAN CURRENT MODELS FORECASTING GIVEN THE
LOCATION OF THE CURRENT ACTIVITY.
WILL HAVE TO WATCH AREA SAT NIGHT INTO SUNDAY AS SEVERAL MODELS ARE
HINTING AT SOME TYPE OF MCS DEVELOPMENT IN NORTHERN AL AND TN. GIVEN
THE NORTHWEST FLOW AND THESE DISTURBANCES...CANT RULE IT OUT. GFS
INSTABILITY FORECAST FOR SUNDAY IS IMPRESSIVE WITH 500 TO 700 MB
LAPSE RATES OVER 8 DEG C/KM FOR NORTHWEST GA. ALONG WITH CAPE
VALUES 2000 TO AS MUCH AS 4000 J/KG ... THERE WILL BE SOME SEVERE
POTENTIAL...HOWEVER SHEAR VALUES ARE LESS THAN MARGINAL SO
CONFIDENCE ON A MORE WIDESPREAD SEVERE EVENT IS LESS. MAIN IMPACTS
WILL BE DAMAGING WINDS AND HAIL. TIMING OF STORMS ON SUNDAY IS A
CRAP SHOOT AT THIS POINT AND MODEL TIMING IS ALL OVER THE PLACE
GIVEN THE POTENTIAL MCS DEVELOPMENT EARLY ON SUN. NEEDLESS TO
SAY...WILL NEED TO WATCH THE FORECAST CLOSELY THROUGH THE WEEKEND AS
IT COULD CHANGE SIGNIFICANTLY FOR BETTER OR WORSE.
HIGH PW VALUES AND THE SLOW MOVING NATURE OF THESE DISTURBANCES HAVE
THE POTENTIAL TO PRODUCE SOME ISOLATED FLASH FLOODING...PARTICULARLY
ACROSS NORTH GA BOTH SAT AND SUN. WILL NEED TO ALSO MONITOR THIS AS
WELL AS THE SEVERE THREAT.
30
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HAVE ADJUSTED POPS UPWARD FOR SUNDAY NIGHT ACROSS THE CWFA. MODELS
ARE SHOWING SIGNS OF AN MCS DEVELOPING IN THE NW FLOW AND AFFECTING
THE CWFA. STRONG SURFACE INSTABILITY AND VERY STEEP LAPSE RATES WILL
HELP SUSTAIN CONVECTION AND CONTINUE THE POSSIBILITY OF SEVERE
STORMS AT LEAST THROUGH MIDNIGHT.
FOR MONDAY...A 500MB TROUGH/SHEAR AXIS SETS UP RIGHT ALONG THE SE
COAST. THIS FEATURE SHOULD SERVE TO FOCUS ANY CONVECTIVE ACTIVITY
FOR MONDAY AND MONDAY EVENING. DO THINK SHRA/TSRA WILL BE MORE
DIURNAL IN NATURE. KEPT THE TREND OF HIGHEST POPS IN THE EAST...WITH
ONLY ISOLATED ACTIVITY TO THE WEST.
WEAK SHEAR AXIS/500MB TROUGH MOVES OFF THE COAST ON TUESDAY WITH
RIDGING BUILDING ALOFT ACROSS THE CWFA. ANY CONVECTION SHOULD BE
ISOLATED IN NATURE...SURFACE INSTABILITY WILL BE PRESENT BUT NO
DISCERNIBLE SURFACE MECHANISM TO FOCUS PRECIP IS NOTED. PRECIP
SHOULD BE DIURNAL.
UNCERTAINTY BEGINS TO CREEP INTO THE FORECAST BY WEDNESDAY. EARLIER
MODEL RUNS PROGGED A COLD FRONT TO MOVE THROUGH THE CWFA DURING THE
LATTER HALF OF THE WEEK. THE ECMWF NOW KEEPS THE FRONT TO THE
NORTH...WHILE THE GFS DOES MOVE THE BOUNDARY THROUGH SLOWLY FRIDAY
THROUGH SATURDAY. HAVE OPTED TO GO PERSISTENCE FOR THIS PERIOD DUE
TO LOW CONFIDENCE.
NLISTEMAA
&&
AVIATION...
06Z UPDATE...
SHOWERS AND A FEW EMBEDDED TSTORMS WORKING EAST OUT OF AL INTO GA
TONIGHT. TIME OF ARRIVAL ON MAIN CELLS FOR ATLANTA AREA SITES
BETWEEN 07Z AND 08Z BUT AM NOT CONFIDENT THEY WILL HOLD TOGETHER
AS AIRMASS IS A LITTLE MORE STABLE ACROSS GA. THIS IS EVIDENT IN THE
LARGER CELL WEST OF CSG WHICH HAS BEEN WEAKENING AS IT MOVES EAST.
DID INCLUDE TSRA IN A TEMPO GROUP AT ATL OVERNIGHT FOR SOME OF THE
STRONGER CELLS. HRRR AND HIGH RES MODELS CONTINUE TO SHOW THE EAST WEST
BANDING OF STORMS THROUGH MID MORNING BUT PRIMARILY OVER AL AND
EXTREME WESTERN GA. WILL NEED TO MONITOR THIS FOR ANY SLIGHT
EASTWARD EXTENSION AND THE NEED TO AMD WITH THUNDER.
OTHERWISE...BELIEVE CLOUD DEBRIS WILL HAMPER EARLY TS DEVELOPMENT
ON SAT BUT STILL THINK TSTORMS WILL DEVELOP IN THE AFTERNOON
PARTICULARLY ACROSS NORTH GA. MVFR CIGS AND VSBYS ARE POSSIBLE
OVERNIGHT PARTICULARLY IN SHOWERS MAINLY BETWEEN 08Z AND 12Z AND
WINDS ARE EXPECTED TO REMAIN GENERALLY LIGHT OUT OF THE SOUTHWEST
BUT INCREASING TO AROUND 10KTS AFTER 16Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS
30
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 80 63 79 65 / 60 60 60 60
ATLANTA 78 65 79 66 / 70 70 60 60
BLAIRSVILLE 73 60 76 60 / 70 70 70 70
CARTERSVILLE 78 63 79 65 / 70 70 60 50
COLUMBUS 83 67 85 67 / 50 50 40 50
GAINESVILLE 76 63 76 63 / 70 70 70 60
MACON 85 64 84 66 / 50 50 60 60
ROME 79 63 81 65 / 70 70 60 40
PEACHTREE CITY 79 64 79 65 / 60 60 60 60
VIDALIA 88 69 87 68 / 40 40 60 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...30
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
214 AM EDT SAT MAY 18 2013
.PREV DISCUSSION... /ISSUED 920 PM EDT FRI MAY 17 2013/
UPDATE...
RE-ADJUSTED POPS AND WEATHER GRIDS TO ACCOUNT FOR CURRENT TRENDS...
BETTER CONVECTION IS SHIFTING SOUTH ACROSS ALABAMA ALONG THE BETTER
THETA-E AXIS. PLENTY OF LIGHT TO MODERATE SHOWERS STILL MOVING INTO
WESTERN PORTIONS OF THE FORECAST AREA...AND CANNOT RULE OUT SOME
THUNDER THROUGH THE OVERNIGHT WITH THE UPPER LOW SPINNING IN THE
VICINITY. THE REMAINDER OF THE FORECAST LOOKS OK FOR NOW SO LITTLE OR
NO CHANGES MADE AT THIS TIME.
20
PREV DISCUSSION... /ISSUED 805 PM EDT FRI MAY 17 2013/
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
SCATTERED TO BROKEN CLOUD COVER PREVAILED OVER NORTH AND CENTRAL GA
AT THIS TIME WITH A FEW LIGHT SHOWERS. THE UPPER LEVEL TROUGH OVER
THE MS RIVER VALLEY HAS ASSOCIATED SHORT WAVES ROTATING THROUGH
NORTH AL AND CENTRAL TN WITH NUMEROUS SHOWERS AND SCATTERED TSTMS.
MOST MODELS ARE IN AGREEMENT THE TROUGH WILL GRADUALLY MOVE EAST
THROUGH SATURDAY NIGHT. THE UPPER LEVEL DISTURBANCES WILL COMBINE
WITH ADEQUATE GULF MOISTURE...PWS AROUND 1.5 INCHES...TO SPREAD
NUMEROUS SHOWERS AND SCATTERED TSTMS OVER THE NORTH HALF OF GA. WILL
LEAN TOWARD THE NAM...HRRR AND LOCAL WRF MODEL SOLUTIONS WHICH
EXPECT THE SHOWERS AND A FEW TSTMS TO ENTER NORTHWEST GA TONIGHT AND
OVER MOST OF NORTH GA BY MIDNIGHT. THE TSTM POTENTIAL SHOULD
DIMINISH TO ISOLATED LATER TONIGHT AS THE RAIN COOLED AIR STABILIZES
THE AIRMASS OVER THE STATE. DIURNAL HEATING ON SATURDAY WILL TRIGGER
ADDITIONAL TSTMS IN THE AFTERNOON AND EVENING WITH MUCAPES IN THE
1500-2000 J/KG RANGE. A SLIGHT RISK OF SEVERE TSTMS WILL BE
POSSIBLE...MAINLY OVER NORTHWEST GA DUE TO THE CLOSE PROXIMITY OF
THE UPPER LEVEL TROUGH. QPF AMOUNTS OF 1 TO 1.5 INCHES ARE EXPECTED
OVER NORTH GA WITH 0.75 INCH OR LESS OVER CENTRAL GA. TEMPORARY
STREET FLOODING WILL BE POSSIBLE WITH PERIODS OF HEAVY
RAIN...HOWEVER CREEK OR RIVER FLOODING SHOULD BE LIMITED UNLESS MORE
QPF DEVELOPS IN A MUCH SHORTER PERIOD OF TIME. A MET/MAV MOS BLEND
WAS USED FOR MIN AND MAX TEMPS.
16
LONG TERM /SUNDAY THROUGH FRIDAY/...
SHORTWAVE IS IN THE PROCESS OF SHIFTING EAST OF THE CWA ON
SUNDAY...SO THIS...IN ADDITION TO PLENTY OF MOISTURE ACROSS THE
CWA AND FORECAST MUCAPE AROUND 3000 J/KG WILL ALLOW FOR THE TREND
OF SHOWERS AND THUNDERSTORMS TO CONTINUE INTO SUNDAY. HAVE
EXTENDED LIKELY POPS FURTHER WEST THAN PREVIOUS FORECAST FOR
SUNDAY. WITH UPPER RIDGE BUILDING IN FOR MONDAY AND
TUESDAY...POPS DECREASE...BUT THERE IS ENOUGH MOISTURE AROUND TO
KEEP SLIGHT CHANCE TO CHANCE POPS. GFS AND ECMWF STILL DIFFER
WITH MID-WEEK FRONTAL BOUNDARY WITH THE ECMWF FASTER THAN THE GFS
IN THE 12Z RUN. GIVEN DIFFERENCES...HAVE CONTINUED THE TRENDS
ADVERTISED IN THE PREVIOUS FORECAST. THE PREVIOUS DISCUSSION FOLLOWS.
11
LONG TERM /SATURDAY THROUGH THURSDAY/...
MODELS IN GENERAL AGREEMENT FOR SATURDAY TARGETING THE AREA WITH
SCATTERED TO NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS. THIS
DUE TO THE INFLUENCE OF UPPER LOW PRESSURE MOVING TO THE OH/TN
VALLEY AREAS AND THE MAIN UPPER TROUGH AFFECTING GA. WHILE N GA IS
TARGETED WITH THE HIGHEST POPS...INSTABILITY ACROSS THE AREA WILL
ALLOW FOR SCATTERED SHOWERS/STORMS ACROSS CENTRAL GA AS WELL. EVEN
WITH CLOUDS AND PRECIP CHANCES...A WARM AIRMASS IN PLACE WILL
ALLOW FOR HIGH TEMPERATURES NEAR NORMAL.
UPPER SYSTEM IN THE PROCESS OF PASSING THE AREA FOR SUNDAY BUT STILL
PLENTY OF MOISTURE AND INSTABILITY IN PLACE FOR SCATTERED TO
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS. MODELS IN SOME
DISAGREEMENT FOR MONDAY WITH THE GFS WETTER THAN THE EUROPEAN AS THE
EUROPEAN HAS A STRONGER DRIER UPPER RIDGE MOVING OVER THE AREA THAN
THE GFS. GFS CONTINUES TO BE WETTER ON TUESDAY THAN THE EUROPEAN
WITH THE INFLUENCE OF AN UPPER RIDGE OVER THE AREA. STILL PLENTY OF
MOISTURE AND INSTABILITY FOR SOME AFTERNOON/EVENING CONVECTION.
INFLUENCE OF THE UPPER RIDGE DIMINISHES ON WEDNESDAY AS A COLD FRONT
MOVES ACROSS THE MID U.S. THIS WILL ALLOW FOR THE CHANCES OF SHOWERS
AND STORMS ACROSS THE AREA WITH CHANCES A LITTLE HIGHER ACROSS THE
N. GFS/EUROPEAN IN DISAGREEMENT WITH THE FRONT ON THURSDAY WITH THE
GFS MOVING THE FRONT INTO THE AREA AND THE EUROPEAN KEEPING THE
FRONT WELL TO THE NW. MOISTURE AND INSTABILITY WILL AGAIN COMBINE
FOR A CHANCE OF SHOWERS AND STORMS. A WEAK FRONT WILL LIKELY BE IN
THE AREA ON FRIDAY WITH AT LEAST SMALL CHANCES FOR SHOWERS AND
STORMS. TEMPERATURES GENERALLY RUNNING NEAR TO ABOVE NORMAL.
BDL
AVIATION...
00Z UPDATE...
VFR CONDITIONS WILL PREDOMINATE ACROSS THE FORECAST AREA THROUGH THE
MAJORITY OF THIS FORECAST PERIOD...OUTSIDE OF AREAS OF CONVECTION.
THERE IS A CHANCE FOR SOME SCATTERED AREAS OF MVFR CEILINGS AND
VISIBILITIES BETWEEN 02Z AND 14Z...MAINLY IN AREAS THAT SEE BETTER
RAINFALL. BEST CHANCES FOR MAINLY SHOWERS TONIGHT AT THE TAF SITES
WILL BE BETWEEN 02Z AND 09Z AS A LARGE...WEAKENING...AREA OF
CONVECTION MOVES EAST OUT OF ALABAMA. ISOLATED THUNDERSTORMS ARE
POSSIBLE WITH THIS AREA. BETTER CHANCES FOR THUNDER WILL BE AFTER
16Z SATURDAY. WINDS WILL BE FAIRLY LIGHT AND VARIABLE THROUGH 14Z...
BUT WILL FAVOR SOUTHWEST TO SOUTHEAST. SOUTHWEST WINDS WILL INCREASE
TO 6-10KT AFTER 16Z.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS.
20
&&
.AVIATION...
06Z UPDATE...
SHOWERS AND A FEW EMBEDDED TSTORMS WORKING EAST OUT OF AL INTO GA
TONIGHT. TIME OF ARRIVAL ON MAIN CELLS FOR ATLANTA AREA SITES
BETWEEN 07Z AND 08Z BUT AM NOT CONFIDENT THEY WILL HOLD TOGETHER
AS AIRMASS IS A LITTLE MORE STABLE ACROSS GA. THIS IS EVIDENT IN THE
LARGER CELL WEST OF CSG WHICH HAS BEEN WEAKENING AS IT MOVES EAST.
DID INCLUDE TSRA IN A TEMPO GROUP AT ATL OVERNIGHT FOR SOME OF THE
STRONGER CELLS. HRRR AND HIGH RES MODELS CONTINUE TO SHOW THE EAST WEST
BANDING OF STORMS THROUGH MID MORNING BUT PRIMARILY OVER AL AND
EXTREME WESTERN GA. WILL NEED TO MONITOR THIS FOR ANY SLIGHT
EASTWARD EXTENSION AND THE NEED TO AMD WITH THUNDER.
OTHERWISE...BELIEVE CLOUD DEBRIS WILL HAMPER EARLY TS DEVELOPMENT
ON SAT BUT STILL THINK TSTORMS WILL DEVELOP IN THE AFTERNOON
PARTICULARLY ACROSS NORTH GA. MVFR CIGS AND VSBYS ARE POSSIBLE
OVERNIGHT PARTICULARLY IN SHOWERS MAINLY BETWEEN 08Z AND 12Z AND
WINDS ARE EXPECTED TO REMAIN GENERALLY LIGHT OUT OF THE SOUTHWEST
BUT INCREASING TO AROUND 10KTS AFTER 16Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS
30
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 82 64 82 66 / 60 60 60 40
ATLANTA 81 65 82 68 / 70 70 60 30
BLAIRSVILLE 73 57 78 60 / 70 70 70 50
CARTERSVILLE 80 64 82 66 / 70 70 60 20
COLUMBUS 85 67 86 67 / 50 50 30 20
GAINESVILLE 79 64 80 66 / 70 70 60 40
MACON 84 64 85 66 / 50 50 50 30
ROME 80 64 83 66 / 70 70 60 20
PEACHTREE CITY 80 63 84 64 / 60 60 50 20
VIDALIA 87 67 86 68 / 40 40 50 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1137 PM CDT FRI MAY 17 2013
.DISCUSSION...
ISSUED 830 PM CDT FRI MAY 17 2013
01Z/8PM RADAR IMAGERY SHOWS ISOLATED SHOWERS ALONG/NORTHWEST OF A
PETERSBURG TO BLOOMINGTON-NORMAL LINE. THESE SHOWERS WILL CONTINUE
TO DRIFT SLOWLY NORTHWARD BEFORE DISSIPATING BY AROUND 10PM. AFTER
THAT...DRY WEATHER IS ANTICIPATED OVERNIGHT. WITH MOIST DEWPOINTS
IN THE LOWER TO MIDDLE 60S AND VERY LIGHT WINDS...EXPECT FOG TO
DEVELOP AFTER MIDNIGHT. HRRR SUGGESTS VISBYS MAY DROP TO 1SM OR
LESS TOWARD DAWN...HOWEVER THINK THIS MAY BE A BIT TOO AGGRESSIVE
GIVEN THE AMOUNT OF CLOUD COVER THAT SHOULD BE STICKING AROUND. AT
THIS POINT...WILL JUST CARRY PATCHY FOG OVERNIGHT. ZONE UPDATE HAS
ALREADY BEEN ISSUED.
&&
.AVIATION...
ISSUED 1137 PM CDT FRI MAY 17 2013
PERSISTENT CLUSTER OF SHOWERS NEAR KPIA WILL GRADUALLY DISSIPATE
BY 06Z...HOWEVER WILL MAINTAIN VCSH THROUGH 08Z IN CASE A FEW
SHOWERS LINGER. WITH LIGHT WINDS AND PLENTY OF LOW-LEVEL MOISTURE IN
PLACE...PARTIAL CLEARING OVERNIGHT WILL LEAD TO THE DEVELOPMENT OF
PATCHY FOG. BIG QUESTION WILL BE WHETHER OR NOT A LOW OVERCAST
WILL FORM AS WELL. NAM FORECAST SOUNDINGS ARE SUGGESTING CEILINGS
OF AROUND 1000FT OVERNIGHT INTO EARLY SATURDAY MORNING. THINK THIS
IS OVERDONE AND WILL ONLY INCLUDE SCT CLOUD COVER AROUND 1500FT
ALONG WITH 2-4SM FOG OVERNIGHT. ONCE THE MORNING FOG/CLOUDS
LIFT...NEGATIVE CU-RULE POINTS TO A PARTLY SUNNY DAY WITH CLOUD
BASES AROUND 5000FT. WILL INCLUDE VCSH AT KCMI IN CLOSER PROXIMITY
TO UPPER LOW SPINNING OVER THE OHIO RIVER VALLEY. WINDS WILL BE
E/SE AT 10KT OR LESS THROUGH THE ENTIRE 06Z TAF PERIOD.
BARNES
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT FRI MAY 17 2013
AN EXTENDED PERIOD OF RAIN CHANCES WILL CONTINUE INTO THE WEEKEND
AND MOST OF NEXT WEEK. THE MAIN WEATHER FEATURES WILL BE A
STATIONARY FRONT AND UPPER LOW THE REST OF TODAY AND
SATURDAY...THEN A WARM FRONT ACROSS IL AND DEEPENING LOW PRESSURE
IN THE PLAINS ON SUNDAY AND MONDAY...THEN A SLOW MOVING OCCLUDED
LOW MONDAY NIGHT THROUGH TUESDAY NIGHT...BEFORE A COLD FRONT
FINALLY PUSHES ACROSS ILLINOIS ON WEDNESDAY.
THE BEST WINDOW OF OPPORTUNITY FOR ANY LONGER BREAKS IN THE RAIN
MAY BE SATURDAY AND SUNDAY...BUT STRONG INSTABILITY AS THE CAP
ERODES LATE SUNDAY AFTERNOON INTO SUNDAY EVENING MAY ALLOW FOR
STRONG TO SEVERE STORMS SUNDAY NIGHT NORTHWEST OF THE IL RIVER.
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT.
SHOWERS AND THUNDERSTORMS ERUPTED THIS AFTERNOON AS THE CAP
DISSIPATED...BUT COVERAGE WAS ISOLATED FOR THE MOST PART. THE
PRIMARY AREA OF ACTIVITY IN OUR AREA WAS FROM GALESBURG TO
HOOPESTON...CLOSER TO THE STATIONARY FRONT THAT EXTENDED ACROSS
NORTHERN IL. ADDITIONAL SHOWERS DEVELOPED FARTHER SOUTH FROM
JACKSONVILLE TO LAWRENCEVILLE ASSOCIATED WITH THE UPPER LOW MOVING
EAST INTO KENTUCKY. THE FRONT AND LOW WILL CONTINUE TO TRIGGER
SHOWERS AND STORMS INTO THE EVENING...BUT PROGRESSIVELY EAST WITH
TIME. BY MIDNIGHT...WE EXPECT PRECIP TO COME TO AN END IN CENTRAL
IL.
MOST OF THE DAY ON SATURDAY SHOULD BE DRY...BUT WE CAN NOT RULE
OUT SOME DIURNAL SHOWERS AND ISOLATED STORMS EAST OF I-57 AS THE
UPPER LOW LINGERS NEARBY TO THE EAST OF IL. A LULL IN THE RAIN
LOOKS LIKELY SATURDAY NIGHT AND MUCH OF SUNDAY...AS WARM AIR
SURGES INTO THE AREA. DEWPOINTS ON SUNDAY WILL CLIMB INTO THE
LOWER 70S AS HIGH TEMPS REACH THE UPPER 80S. A LOW LEVEL INVERSION
WILL PROVIDE A CAP UNTIL LATE IN THE DAY ON SUNDAY. ELEVATED
INSTABILITY WILL INCREASE DRAMATICALLY BY LATE AFTERNOON...WITH ML
CAPE VALUES AROUND 4K J/KG AND LI`S OF -10C. THE CAP WILL ERODE
FROM WEST TO EAST...REACHING PEORIA TO SPI BY 6-7 PM. SO OUR
WESTERN COUNTIES WILL HAVE THE BEST CHANCES FOR STRONG TO SEVERE
STORMS SUNDAY EVENING. TONED DOWN STORMS ARE EXPECTED TO ADVANCE
EAST TOWARD I-57 AFTER MIDNIGHT SUNDAY NIGHT.
MONDAY LOOKS TO BE LESS LIKELY FOR STORMS THAN PREVIOUS FORECAST
MODEL SOLUTIONS INDICATED. CLOUD COVER WILL KEEP HIGH TEMPS IN THE
LOWER 80S...BUT WE WILL REMAIN IN THE WARM SECTOR. WE REMOVED ANY
LIKELY POPS FROM MONDAY AND KEPT CHANCE POPS ACROSS THE AREA.
INSTABILITY PARAMS BECOME FAVORABLE AGAIN FOR STRONG STORMS MONDAY
EVENING...AS WE BREAK THE INVERSION AGAIN...BUT WE ARE NOT IN THE
SPC DAY 4 OUTLOOK FOR MON-MON NIGHT LIKE WE WERE IN THE DAY 5
OUTLOOK YESTERDAY. LACK OF A SOLID FOCUSING MECHANISM IS ONE OF
THE REASONS WHY. THE WARM FRONT WILL BE NORTH OF OUR AREA...AND
THE OCCLUDED LOW AND ITS ENERGY WILL BE MAINLY IN THE NORTHERN
PLAINS.
LONG TERM...TUESDAY THROUGH FRIDAY.
AS THE OCCLUDED LOW MOVES TOWARD IL ON TUESDAY...AND SETTLES OVER
N-NW IL TUESDAY NIGHT COVERAGE OF SHOWERS AND STORMS WILL BECOME
MORE WIDESPREAD. LIKELY POPS WERE INCLUDED EVERYWHERE BUT THE FAR
WESTERN COUNTIES TUESDAY AND TUESDAY NIGHT...WITH LOCALLY HEAVY
RAINFALL POSSIBLE AS STORM MOTIONS REMAIN SLOW.
THE COLD FRONT WILL EVENTUALLY MOVE ACROSS OUR AREA ON WEDNESDAY
AS THE LOW PRESSURE SYSTEM FINALLY PULLS AWAY TO THE NORTHEAST.
DRIER CONDITIONS WILL BEGIN TO RETURN WED NIGHT...BUT THE COLD
POOL ALOFT WILL KEEP CHANCES OF INSTABILITY SHOWERS IN PLACE FOR
THURSDAY.
THE COLDEST AIR OF THE WEEK WILL COME THURSDAY THROUGH FRIDAY...AS
HIGHS ONLY REACH THE LOW TO MID 70S...AND LOWS DIP INTO THE 50S.
SUNSHINE AND DRY CONDITIONS RETURN FOR FRIDAY...FINALLY.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
354 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT SAT MAY 18 2013
SHORT WAVE RIDGING IS RATHER EVIDENT ON THE 08Z WATER VAPOR IMAGERY
CENTERED OVER THE SOUTHERN AND CENTRAL PLAINS WITH THE RIDGE AXIS
LOCATED ROUGHLY OVER CENTRAL AND EASTERN KANSAS. SURFACE
OBSERVATIONS AT MICROWAVE IMAGERY SHOWS A DECENT STRATUS LAYER
ACROSS CENTRAL AND SOUTHERN KANSAS. EXPECT THIS AREA OF STRATUS TO
MOVE NORTH AND OVER THE FAR WESTERN ZONES THROUGH THE MORNING HOURS
BEFORE EVENTUALLY CLEARING OUT LATER TODAY. WITH THE RIDGE OVERHEAD
AND STRONG LOW/MID LEVEL CAPPING EXPECT A CUMULUS FIELD TO FORM WITH
DIURNAL HEATING...BUT STORMS ARE EXCEEDINGLY UNLIKELY TO FORM DUE TO
THE VERY WARM 700-800 MB TEMPERATURES. EXPECT RATHER WARM
TEMPERATURES TODAY...AS STRONG SUBSIDENCE WILL BE ONGOING DUE TO THE
RIDGE IN PLACE...AS WELL AS MIXING TO AROUND 850 MB. AS A RESULT THE
DAYTIME HIGHS WILL LIKELY REACH THE MIDDLE TO UPPER 80S TODAY.
FURTHER TO THE WEST A WELL PRONOUNCED DRY LINE WILL FORM IN SW/SC
KANSAS AND WILL LIKELY BE THE FOCUS FOR AFTERNOON THUNDERSTORMS ON
SATURDAY AFTERNOON. THESE STORMS WILL BE WELL WEST OF THE FORECAST
AREA IN THEIR STRONGEST FORM...BUT THEY WILL LIKELY ADVECT NORTH AND
EAST THROUGH THE EVENING AND OVERNIGHT HOURS...PERHAPS FORMING AN
OVERNIGHT MCS WHICH WOULD SLIDE EAST-NORTHEAST THROUGH THE FORECAST
AREA SATURDAY NIGHT INTO SUNDAY MORNING. WITH THE AFOREMENTIONED CAP
SOLIDLY IN PLACE ANY STORMS MOVING INTO NORTH CENTRAL AND NORTHEAST
KANSAS WILL HAVE A FORMIDABLE CHALLENGE TO OVERCOME ESPECIALLY THE
FURTHER EAST YOU GO...BUT IT WILL BE POSSIBLE FOR THE
WESTERN/CENTRAL KANSAS CONVECTION TO LEAK INTO THE AREA THIS EVENING
AND OVERNIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 315 AM CDT SAT MAY 18 2013
SUNDAY...SEVERAL MODELS STILL SHOWING CONVECTION THAT DEVELOPS
OVER CENTRAL AND SW KANSAS MOVING NORTHEASTWARD INTO THE FORECAST
AREA THROUGH THE EARLY MORNING HOURS. WITH A CAP IN PLACE OVER
MUCH OF THE FORECAST AREA AM NOT HIGHLY CONFIDENT THAT A
THUNDERSTORM CLUSTER WILL BE ABLE TO ERODE THE CAP ON ITS OWN
ENOUGH FOR LASTING OVERNIGHT STORMS. THIS WILL HAVE SOME IMPACT
ON THE SEVERE WEATHER CHANCES FOR SUNDAY AFTERNOON...ALTHOUGH JUST
ABOUT ALL COMPUTER DEPICTIONS LIFT PRECIP OFF TO THE NORTH AS THE
CAP ALOFT REDEVELOPS IN THE AFTERNOON. COULD ALSO SEE SOME
ISOLD/SCT STORMS NORTH NEAR THE NEBRASKA BORDER ON THE EDGE OF THE
STRONGER CAPPING INVERSION.
SUNDAY AFTERNOON AND EVENING ARE STILL SHAPING UP TO BRING THE
CHANCE FOR SIGNIFICANT SEVERE WEATHER TO THE REGION. BY 18Z THE
UPPER TROF IS APPROACHING EASTERN KS WITH A NEGATIVE
TILT...SURFACE LOW HAS SHIFTED TO CENTRAL KANSAS AND INSTABILITY
INCREASES INTO 2500-3500J/KG...WITH THE NAM AS HIGH AS 4500 OUT
WEST OF MANHATTAN. 0-6KM BULK SHEAR RISES FROM 35KTS TO NEAR 50KTS
AROUND 0Z IN THE EASTERN COUNTIES...WITH THE GFS SHOWING 35KTS
FROM 0-1KM. LAPSE RATES ALOFT ARE 9C OR GREATER FOR A GOOD PORTION
OF THE SOUNDING...WITH AN UPPER JET MOVING PERPENDICULAR ACROSS
THE SURFACE TROF ALONG THE KS/OK BORDER THROUGH THE EVENING HOURS.
WITH SUCH STRONG INSTABILITY AND LAPSE RATES...AND GIVEN LACK OF
STRONG TURNING WITH HEIGHT IN THE WIND PROFILE...INITIAL THINKING
IS THAT LARGE HAIL...BASEBALL SIZE OR LARGER...IS A POSSIBILITY
WHERE STORMS CAN FORM LATER SUNDAY AFTERNOON. CANNOT RULE OUT
ISOLATED TORNADOES GIVEN STRONG INSTABILITY AND AVAILABLE SHEAR IN
THE COLUMN...AND WILL ALSO NEED TO KEEP WIND THREAT IN MIND FROM
NOT ONLY STRONG DISCRETE CELLS BUT ALSO POTENTIAL FOR LINE OF
STORMS TO FORM AND MOVE EASTWARD. MUCH OF THE EAST AND SOUTHEAST
PORTIONS OF OUR FORECAST AREA HAVE BEEN PUT IN A MODERATE DAY 2
RISK FOR THIS POTENTIAL. CHANCES FOR OVERNIGHT ACTIVITY MAY ALSO
HAVE AN INFLUENCE ON TIMING AND ONSET OF SEVERE WEATHER ON SUNDAY.
AT THIS TIME THINK BEST CHANCES ARE IN THE AFTERNOON INTO THE
EVENING HOURS...WITH LARGE HAIL...WIND GUSTS AND ISOLATED
TORNADOES A POSSIBILITY...WITH THE GREATER THREAT IN AREAS EAST OF
ABILENE. 67
FOR SUNDAY NIGHT...EC WANTS TO MOVE THE SECONDARY MAIN LOW OVER THE
AREA GOING INTO TUESDAY MORNING WHICH MAY TRIGGER YET ANOTHER LINE
OF SHOWERS AND STORMS FOR THE CENTRAL DN SC PARTS OF THE STATE. KEPT
HIGHER POPS ACROSS THE SE FOR POSSIBLY BOUNDARY HANGING UP OVER
THAT AREA.
TUESDAY AND WEDNESDAY UPPER LOW CONTINUES TO SLOWLY SIT AND SPIN
OVER THE NORTHERN PLAINS THROUGH THURSDAY BEFORE IT STARTS TO
SHIFT EASTWARD. COOLER THAN NORMAL TEMPERATURES MAKE A BRIEF
RETURN THROUGH FRIDAY AS COOLER HIGH PRESSURE SETTLES SOUTHWARD
FROM THE NORTHERN PLAINS. 67
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1142 PM CDT FRI MAY 17 2013
CONFIDENCE IN IFR VSBY IS IS DIMINISHING AS OBJECTIVE GUIDANCE HAS
COME IN AND BACKED OFF ON VSBY RESTRICTIONS AND WINDS HAVE NOT
BEEN AS LIGHT AS EXPECTED. STILL THINK THERE WILL BE ENOUGH
RADIATIONAL COOLING FOR SOME MVFR VSBY TO OCCUR...BUT WILL REMOVE
THE MENTION OF IFR VSBY. DO NOT HAVE ANY CONFIDENCE IN THE NAM
GENERATING MID DAY CONVECTION IN SOUTHEASTERN KS. THERE IS NO GOOD
EXPLANATION FOR THE NAMS DISJOINTED COOLING OF MID LEVEL TEMPS
WHICH WEAKENS THE CAP. THE RAP ON THE OTHER HAND SHOWS THE CAP
HOLDING THROUGH THE LATE AFTERNOON WITH SFC TEMPS WARMING TO
AROUND 90. THEREFORE WILL KEEP THE TERMINALS DRY THROUGH THE
FORECAST.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LEIGHTON
LONG TERM...CRAVEN
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1142 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 725 PM CDT FRI MAY 17 2013
WITH THE LATEST RAP AND NAM MODELS SHOWING THE STRATUS REMAINING
MAINLY TO THE SOUTHWEST OF THE FORECAST AREA LATE TONIGHT...AM A
LITTLE CONCERNED FOR SOME GROUND FOG FORMATION BETWEEN 08 AND 10Z
THINKING WINDS WILL BE LESS THAN 5 KTS AND SKIES MOSTLY CLEAR.
DEWPOINT TEMPS ACROSS SOUTHERN MO IN THE LOWER 60S AND A
PERSISTENT SOUTHEAST WIND SUGGEST DEWPOINTS ARE MOT LIKELY TO DROP
OFF MUCH TONIGHT. BECAUSE OF THIS HAVE INSERTED A MENTION OF
PATCHY FOG FOR LATE TONIGHT AND EARLY SATURDAY MORNING.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 342 PM CDT FRI MAY 17 2013
SCATTERED TO BROKEN STRATOCU DECK ACROSS THE EASTERN 2/3 OF THE
COUNTY WARNING AREA WILL GRADUALLY DECREASE AFT PEAK
HEATING...BEFORE REDEVELOPING/THICKENING AGAIN LATER TONIGHT AS
MOIST AXIS LIFTS NORTHWARD TOWARDS THE CWA. WILL KEEP THE FCST DRY
THROUGH TONIGHT...BUT INCREASE CLOUDS LATER AGAIN SOUTHWEST TO
NORTHEAST. ALTHOUGH NOT AS DENSE AS LAST NIGHT...STILL THINK SOME
FOG MAY FORM WITH THE STRATUS LATE...BUT NOT DENSE ENOUGH TO INSERT
INTO GRIDS AT THIS POINT. LOWS SHOULD BE IN THE LOW TO MIDDLE 60S.
EXPECT THIS STRATUS DECK SHOULD THIN AGAIN BY MIDDAY/AFTERNOON
SATURDAY ALLOWING FOR HIGH TEMPS TO WARM INTO THE MIDDLE 80S. MODELS
DIFFER ON WHETHER CAPPING INVERSION BY MIDDAY/AFTERNOON CAN BE
OVERCOME ENOUGH FOR SOME SCT CONVECTION TO DEVELOP AS A WEAK WAVE
APPROACHES FROM THE SOUTHWEST. HOWEVER...WITH A STRENGTHENING
ELEVATED MIXED LAYER WITH LITTLE IN THE WAY OF FORCING IN THAT
LAYER...FEEL THE MODELS MAY BE UNDER DOING CINH AND HAVE DECIDED TO
CONTINUE WITH A DRY FCST...OR MORE IN LINE WITH THE EC MODEL.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 342 PM CDT FRI MAY 17 2013
MODELS CONTINUE TO SIGNAL FOR SOME CONVECTION TO DEVELOP ABOVE THE
CAPPING INVERSION SATURDAY NIGHT AS THE LOW LEVEL JET INCREASES AS
WELL AS ISENTROPIC LIFT. WITH NOT HIGH CONFIDENCE WILL CONTINUE TO
KEEP POPS AROUND 20 PERCENT.
BY 12Z SUNDAY THE UPPER TROUGH AXIS WILL MOVE TO NEAR THE WESTERN
KANSAS BORDER. THE SURFACE LOW WILL CONTINUE TO DEEPEN IN WESTERN
KANSAS. SOME ELEVATED STORMS ARE POSSIBLE SUNDAY MORNING FROM ANY
OVERNIGHT DEVELOPMENT. THE UPPER TROUGH WILL MOVE OUT INTO THE
PLAINS SUNDAY TAKING ON A NEGATIVE TILT. THE TROUGH AXIS LOOKS TO
PASS TO THE EAST OF THE CWA SUNDAY NIGHT. ZERO TO 6 KM SHEAR OF 30
TO 40 KTS...1500-2500 J/KG OF ML CAPE ALONG WITH ABUNDANT MOISTURE
IN THE WARM SECTOR. LAPSE RATES STEEPEN AS THE UPPER TROUGH PIVOTS
NORTHEAST AND ERODES THE CAPPING INVERSION. WILL CONTINUE WITH
LIKELY CHANCES OF THUNDERSTORMS IN THE EASTERN 2/3RDS OF THE CWA ON
SUNDAY AFTERNOON WITH THE HIGHER POPS OVER EAST CENTRAL KANSAS
SUNDAY EVENING. GIVEN SHEAR AND INSTABILITY WITH ABUNDANT MOISTURE
STRONG TO SEVERE STORMS ARE POSSIBLE WITH LARGE HAIL AND DAMAGING
WINDS THE MAIN THREAT. THE TORNADO THREAT REMAINS SUNDAY AND SUNDAY
EVENING...ALTHOUGH NOT MUCH CURVATURE TO THE HODOGRAPHS AND TURNING
IN THE FORECAST HODOGRAPHS CANNOT RULE OUT ANY WITH SUPERCELLS.
MONDAY IS STILL A LITTLE BIT OF A QUESTION MARK AS TO HOW FAR
SOUTHEAST THE BOUNDARY WILL SET UP ACROSS EAST CENTRAL KANSAS SO
WILL CONTINUE TO KEEP THE HIGHER THUNDERSTORM CHANCES IN THE
SOUTHEAST CWA. STRONG TO SEVERE STORMS WILL AGAIN BE POSSIBLE MONDAY
AFTERNOON AND EVENING. THE UPPER LOW CONTINUE TO SPIN OVER THE
CENTRAL PLAINS THROUGH WEDNESDAY. THIS WILL KEEP SMALL CHANCES OF
SHOWERS AND THUNDERSTORMS TUESDAY THROUGH EARLY THURSDAY. A RIDGE
BUILDS OVER THE PLAINS LATE THURSDAY AND FRIDAY BRINGING AN END TO
THE PRECIPITATION CHANCES. FROM MONDAY THROUGH FRIDAY TEMPERATURES
WILL BE IN THE 70S FOR HIGHS AND 50S FOR LOWS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1142 PM CDT FRI MAY 17 2013
CONFIDENCE IN IFR VSBY IS IS DIMINISHING AS OBJECTIVE GUIDANCE HAS
COME IN AND BACKED OFF ON VSBY RESTRICTIONS AND WINDS HAVE NOT
BEEN AS LIGHT AS EXPECTED. STILL THINK THERE WILL BE ENOUGH
RADIATIONAL COOLING FOR SOME MVFR VSBY TO OCCUR...BUT WILL REMOVE
THE MENTION OF IFR VSBY. DO NOT HAVE ANY CONFIDENCE IN THE NAM
GENERATING MID DAY CONVECTION IN SOUTHEASTERN KS. THERE IS NO GOOD
EXPLANATION FOR THE NAMS DISJOINTED COOLING OF MID LEVEL TEMPS
WHICH WEAKENS THE CAP. THE RAP ON THE OTHER HAND SHOWS THE CAP
HOLDING THROUGH THE LATE AFTERNOON WITH SFC TEMPS WARMING TO
AROUND 90. THEREFORE WILL KEEP THE TERMINALS DRY THROUGH THE
FORECAST.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...WOLTERS
SHORT TERM...63
LONG TERM...53
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
359 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL SOUTH OF THE AREA THIS WEEKEND OVER
THE CENTRAL APPALACHIANS AND SOUTHERN MID-ATLANTIC STATES WHILE
ONSHORE FLOW KEEPS THE FORECAST AREA SEASONABLY COOL. THE FRONTAL
BOUNDARY WILL LIFT NORTH OF THE AREA EARLY IN THE WEEK FOLLOWED BY
HIGH PRESSURE BUILDING OVER THE EASTERN STATES THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
FRONTAL BOUNDARY HAS BECOME NEARLY STATIONARY...LOCATED ALONG THE
COASTAL VIRGINIA/NORTH CAROLINA BORDER AND SNAKING ITS WAY BACK
THROUGH/UP THE CENTRAL APPALACHIANS. MEANWHILE...HIGH PRESSURE WAS
LOCATED ALONG THE NEW ENGLAND COAST.
RADAR IMAGERY SHOWED SHOWERS WITH EMBEDDED THUNDERSTORMS ACROSS
CENTRAL AND SOUTHERN VIRGINIA...TO NORTH OF THE BOUNDARY IN A ZONE
OF ISENTROPIC LIFT/ELEVATED INSTABILITY ENHANCED BY PVA FROM A VORT
MAX AT 500 MB. SHOWERS HAVE SNEAKED UP INTO THE CENTRAL VIRGINIA
FOOTHILLS AREA OF THE CWA EARLY THIS MORNING.
THIS FORECAST CYCLE...WHAT IS CERTAIN OVER THE NEXT 24 HOURS IS THAT
EAST-SOUTHEAST FLOW IN THE LOW LEVELS WILL PREVAIL
TODAY/TONIGHT...RESULTING IN CLOUDY SKIES. THIS WILL LEAD TO COOLER
TEMPERATURES TODAY AND GUIDANCE IS IN SOMEWHAT BETTER AGREEMENT THAN
24 HOURS AGO FAVORING THE PREVIOUS COOLER SOLUTION FOR BELOW NORMAL
MAXIMA. BLENDED BIAS CORRECTED MAV/MET WHICH FAVORS UPPER 60S TO
LOWER 70S MAXIMA TODAY...AND THEN MINIMA ABOVE NORMAL TONIGHT IN THE
UPPER 50S TO LOWER 60S.
WHAT IS UNCERTAIN ARE THE DETAILS REGARDING PRECIPITATION. PLENTY OF
DIVERGENCE AMONG THE MODELS IS ALREADY APPARENT WITH THE SHOWERS ON
RADAR NOW...AND WHAT THEIR FATE WILL BE LATER THIS MORNING AND
BEYOND. 03Z HRRR MOVES/FURTHER DEVELOPS THESE SHOWERS TO THE NORTH
THROUGH MORNING...TAKING THEM ALL THE WAY TO THE MASON DIXON LINE BY
LATE MORNING. WRF-ARW/GFS SOLUTIONS GENERALLY KEEP SHOWERS ACROSS
THE SOUTHERN THIRD TO HALF OF THE CWA DURING THE DAY TODAY. THE NAM
AND SREFS ARE SOMEWHERE IN BETWEEN.
INITIALLY...FORECAST IS HEAVILY WEIGHTED TOWARD THE WRF-ARW/GFS
SOLUTIONS /AND RADAR TRENDS/ THIS MORNING THEN BLENDS WITH THE
NAM/SREFS SOLUTIONS FOR THE AFTERNOON AND INTO TONIGHT WITH THE
THINKING THAT LIFT AND THUS SHOWERS EXPAND TO THE NORTH WITH TIME
WITH LIKELY POPS ACROSS THE ENTIRE CWA OVERNIGHT. OBVIOUSLY IF THE
HRRR IS CORRECT THERE WILL BE RAINFALL FURTHER NORTH AND SOONER
THAN WHAT THE FORECAST REFLECTS...AND WILL CONTINUE TO MONITOR
THROUGH THE MORNING BUT FOR NOW THIS HAS BEEN LARGELY DISCOUNTED.
COOL WEDGE WILL BE PRESENT ACROSS MUCH OF THE CWA TO PRECLUDE
THUNDER. HOWEVER GUIDANCE SUGGESTS SOME INSTABILITY ACROSS THE
SOUTHWEST CWA THIS AFTERNOON/EARLY EVENING CLOSER TO THE SNAKING
FRONTAL BOUNDARY. THEREFORE...CONTINUE TO INCLUDE CHANCE OF THUNDER
IN THIS AREA AND ANY CONVECTION MAY BE EFFICIENT RAINFALL PRODUCERS
FOR LOCALLY HEAVY RAINFALL.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
FRONTAL BOUNDARY WILL REMAIN STALLED ACROSS SRN VA ON SUN WHILE SFC
RIDGE FROM HIPRES OFF THE NEW ENGLAND COAST WILL EXTEND WWD INTO NJ
AND PA. SFC PATTERN WILL YIELD A CONTINUED ONSHORE FLOW ACROSS THE
CWA ON SUN. REMNANT MID-LVL SHORTWAVE TROUGH WILL MEANDER OVER THE
CENTRAL APPALACHIANS AS IT REMAINS EMBEDDED WITHIN WEAK STEERING
PATTERN OF THE ERN CONUS RIDGE. FLOW VEERS WITH HEIGHT WITH SLY FLOW
AT H8-7 PROMOTING ISENTROPIC LIFT. CLOUDS AND PERIODS OF SHOWERS
EXPECTED ON SUN. THE HEAVIEST QPF AND CAT POPS RESIDE OVER CENTRAL
VA AND LWR SRN MD...WHERE LIFT MAY BECOME ENHANCED NEAR THE BOUNDARY
AND NORTH OF THE MID-LVL TROUGH. MOST OF THE CWA WILL BE WEDGED IN
STABLE MARINE AIRMASS ALTHOUGH LOCATIONS IN CENTRAL VA MAY TAP INTO
SOME INSTABILITY CLOSER TO THE BOUNDARY. WILL NEED TO MONITOR THE
CONDITIONAL RISK FOR FLOODING OVER THESE AREAS IF CONVECTION
DEVELOPS. WPC HAS HIGHLIGHTED CENTRAL VA WITH A SLIGHT RISK FOR
EXCESSIVE RAINFALL ON SUN.
CLOUDS AND ONSHORE FLOW WILL LIMIT DIURNAL HEATING/COOLING SUN-SUN
NGT. HIGHS NEAR 70F ON SUN AND LOWS IN THE 60S SUN NGT WILL BE
COMMON.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE MID-ATLANTIC REGION WILL BE SITUATED ALONG WRN PERIPHERY OF AN
UPPER RIDGE THROUGH MIDWEEK. PERSISTENT AND DEEP RETURN FLOW AROUND
THE RIDGE WILL CONTINUE TO SUPPLY WARM/MOIST AIR FOR OUR AREA. WITH
THE PREVIOUSLY STALLED FRONTAL BOUNDARY LIFTING NORTH OF THE AREA ON
MON...INSTABILITY AND MOISTURE WILL BE GREATER IN WARM SECTOR. DAILY
CHANCES FOR SHOWERS AND TSTMS WILL BE HIGHEST DURING THE PEAK
HEATING HRS. DURING THE FIRST HALF OF THE WORK WEEK...MON EXPECTED
TO HAVE THE BEST COVERAGE OF PRECIP WITH THE LINGERING MID-LVL
SHORTWAVE TROUGH NEARBY. POPS TUE AND WED WERE CONFINED TO THE
HIGHER TERRAIN WITH OROGRAPHIC LIFT THE PRIMARY DRIVING MECHANISM
FOR DIURNAL CONVECTION. MAX TEMPS NEAR 80F ON MON AND MU80S TUE/WED.
CHANCES FOR SHOWERS AND STORMS INCREASE LATE WEEK WITH THE APPROACH
OF A MIDWEST TROUGH. WARM/HUMID AIRMASS REMAINS IN PLACE DURING THIS
TIME.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AS MENTIONED IN THE NEAR TERM DISCUSSION...THERE IS SOME UNCERTAINTY
REGARDING ONSET OF PRECIPITATION. HAVE DISCOUNTED RECENT RUNS OF THE
HRRR AND BLENDED OTHER MODELS FOR ONSET TIMING. THERE ALSO IS SOME
UNCERTAINTY REGARDING THE ONSET OF FLIGHT RESTRICTIONS. WITH
EAST-SOUTHEAST FLOW...EXPECT CIGS TO FALL TODAY/TONIGHT. CLOSELY
FOLLOWED A GFS LAMP SOLUTION...WHICH BRINGS IFR CONDITIONS MAINLY
AFTER DARK AND THEN LIFR CONDITIONS AFTER MIDNIGHT. IF PRECIPITATION
DEVELOPS SOONER THAN CURRENTLY FORECAST...THEN LOWER FLIGHT
CONDITIONS MAY ALSO DEVELOP SOONER. IN COOL WEDGE...AM NOT EXPECTING
A CHANCE OF THUNDER THIS AFTERNOON AT MOST TAF SITES EXCEPT FOR CHO
WHERE THERE WILL BE SOME INSTABILITY HOWEVER CONFIDENCE IS TOO LOW
TO MENTION AT CHO AT THIS POINT.
MVFR CIGS SUN WITH ONSHORE FLOW CONTINUING. CIGS LIKELY RETURN TO
IFR SUN NGT. WARM FRONT EVENTUALLY LIFTS NORTH OF THE REGION ON MON.
FLIGHT RULES RETURN TO VFR ERY NEXT WEEK...ALTHOUGH BRIEF
RESTRICTIONS POSSIBLE IN SHRA/TSRA.
&&
.MARINE...
WITH HIGH PRESSURE MOVING OFF THE NEW ENGLAND COAST AND A FRONTAL
BOUNDARY STALLED TO THE SOUTH OF THE WATERS...EAST-SOUTHEAST WINDS
WILL SET UP TODAY/TONIGHT. WHILE WE EXPECT WINDS TO PREVAIL 10 TO 15
KT...SOME LOCAL ENHANCEMENT IS EXPECTED ALONG THE LOWER TIDAL
POTOMAC RIVER/LOWER MD CHESAPEAKE BAY WHERE A SCA IS IN EFFECT
TODAY. THIS COULD NEED TO BE EXTENDED INTO TONIGHT. IN
ADDITION...SOMETIMES THIS FLOW IS UNDER-FORECAST BY THE MODELS AND
WILL HAVE TO MONITOR THE NEED FOR NORTHERN EXPANSION UP THE CHANNEL
OF THE BAY.
ELY FLOW 10-15 KT ON SUN. WINDS BECOME SLY ONCE A WARM FRONT PASSES
THRU ON MON. SCA MAY BE NEEDED MON FOR THE MARINE ZONES THAT ARE
SUSCEPTIBLE TO SLY-CHANNELING.
&&
.TIDES/COASTAL FLOODING...
POSITIVE TIDAL ANOMALIES WILL GRADUALLY INCREASE THRUOUT THE
WEEKEND AS ONSHORE FLOW PERSISTS. SLY WINDS DEVELOP ON MON WHEN A
WARM FRONT LIFTS NORTH OF THE AREA. WILL NEED TO MONITOR TIDAL
LVLS THOUGH THE THREAT OF COASTAL FLOODING WILL BE RELATIVELY LOW
JUST PAST THE FIRST QUARTER MOON.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR ANZ534-537-543.
&&
$$
SYNOPSIS...JRK
NEAR TERM...BPP
SHORT TERM...JRK
LONG TERM...JRK
AVIATION...BPP/JRK
MARINE...BPP/JRK
TIDES/COASTAL FLOODING...JRK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
511 AM EDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT SAT MAY 18 2013
IN THE LARGE SCALE...TROUGH OVER THE ROCKIES WILL SLIDE ONTO THE
HIGH PLAINS BY SUNDAY MORNING ALLOWING RIDGING TO SLIGHTLY BUILD
OVER THE WESTERN GREAT LAKES. ALTHOUGH SFC-H85 TROUGHING OVER THE
DAKOTAS DOES NOT MOVE MUCH TO THE EAST...IT IS ENOUGH TO INCREASE
LOW-LEVEL SOUTHERLY FLOW ACROSS THE UPPER GREAT LAKES. PATTERN IS
SERVING TO INCREASE MOISTURE /PWATS 1.15 OF 1.31 INCHES AT GRB AND
MPX OR AROUND 200 PCT OF NORMAL/ IN WAKE OF DRY SFC HIGH THAT HAS
BEEN ESTABLISHED OVER THE AREA FOR MOST OF THIS WEEK. REGIONAL RADAR
SHOWS DECAYING ECHOES OVER NORTHERN WISCONSIN. MUCH MORE ORGANIZED
AREA OF SHRA/TSRA HAVE DEVELOPED SINCE 03Z FROM CENTRAL MINNESOTA
INTO WEST CENTRAL WISCONSIN ALONG H85 WARM FRONT/GRADIENT OF H85
THETA-E. ADDITIONAL AREA OF SHRA/TSRA SPREADING ACROSS NORTHEAST
SOUTH DAKOTA INTO SOUTHEAST NORTH DAKOTA NEAR CONVECTIVE INDUCED
SHORTAVE/H7-H3 DIFFERENTIAL PVA AND CLOSE TO H7 MOISTURE TRANSPORT.
JUST RECENTLY ANOTHER LARGE CLUSTER OF SHRA/TSRA HAVE FORMED IN THE
WARM AIR ADVECTION REGIME BTWN THESE TWO INITIAL AREAS OF PRECIP.
GIVEN EXTENT OF SHRA/TSRA UPSTREAM OF CWA THIS MORNING AND SINCE
H85-H7 MOISTURE ADVECTION IS FORECAST WEST TO EAST ACROSS CWA
THROUGH THE DAY...INCREASED POPS FOR MOST OF THE WEST AND NORTHERN
CWA AS AT LEAST MULTIPLE REMNANTS OF THIS CONVECTION SHOULD MAKE IT
INTO UPR MICHIGAN. LEANED ON THE NCEP WRF MODELS AND RECENT HRRR AND
EXTRAPOLATION OF LATEST HRRR TO CREATE POPS. RESULT IS LIKELY POPS
MOST OF THE DAY OVER THE WEST HALF...WITH SMALLER CHANCES FARTHER
EAST AS THE RAIN RUNS INTO THE VERY DRY AIRMASS ASSOCIATED WITH SFC
HIGH TO THE EAST. MAJORITY OF TSRA THUS FAR STAYING OVER NORTHERN
MINNESOTA ON GRADIENT OF 1-6KM MUCAPE RESERVOIR. HINT IN MODELS
THAT EASTERN EDGE OF INSTABILITY GRADIENT SLIDES TOWARD WESTERN UPR
MICHIGAN SO HAVE INCLUDED SLIGHT CHANCES FOR TSRA. CONVECTION IS
ELEVATED AND MID-LEVEL LAPSE RATES BARELY GET ABOVE 6C/KM. MAIN
ISSUE WILL BE HEAVY DOWNPOURS AND LIGHTNING STRIKES. TEMPS TODAY
A BIT TOUGH TO FIGURE OUT. EAST GRADIENT WINDS SHOULD KEEP KEWEENAW
CHILLY WITH READINGS STAYING BLO 50 DEGREES. MIXING TO H9 IS PROBABLY
IT WHERE CLOUDS/RAIN PERSIST MOST OF THE DAY. THIS SUPPORTS MAJORITY
OF CWA SEEING HIGHS IN THE 60S...EVENTUALLY...ONCE THE STEADIER RAIN
TAPERS OFF THIS AFTN. SFC WARM FRONT MAY TRY TO POKE INTO FAR SW CWA
LATE IN THE DAY. IF THIS OCCURS AND PRECIP TAPERS OFF/ENDS...THEN
THERE IS POTENTIAL FOR HIGHS TO PUSH WELL INTO THE 70S FROM IWD TO
IMT.
H85 FRONT LIFTS NORTH OF MOST CWA THIS EVENING. KEWEENAW STILL CLOSE
ENOUGH TO FRONT AND WITHIN THE RIBBON OF PERSISTENT MOISTURE
ADVECTION SO KEPT SHRA/ISOLD TSRA THERE THROUGH THE EVENING. DRYING
TREND TAKES HOLD OVERNIGHT AS THE FOCUS FOR SHRA/TSRA...H85 WARM
FRONT AND THETA-E GRADIENT...LIFTS WELL TO NORTH OF UPR MICHIGAN.
KEPT SMALL POPS IN AT ISLE ROYALE LATE TONIGHT THOUGH. TEMPS MOSTLY
IN THE 40S EAST WITH FLOW OFF LK MICHIGAN. LESS MODIFIED AIR FARTHER
WEST ALLOWS MINS TO ONLY FALL INTO THE LOW-MID 50S ALONG LK SUPERIOR
AROUND IWD TO ONTONAGON AND EAST TO BARAGA/L`ANSE AND MARQUETTE
AREAS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 510 AM EDT SAT MAY 18 2013
NAM SHOWS THE 500 MB RIDGE OVER THE EASTERN U.S. 12Z SUN WITH
TROUGHING IN THE ROCKIES. THE TROUGH MOVES EAST ON SUNDAY AND PUSHES
THE RIDGE INTO THE LOWER GREAT LAKES 12Z MON WHERE THE MOVEMENT
EASTWARD STOPS THROUGH 12Z TUE. NAM HAS SOME DEEPER MOISTURE AND
850-500 MB Q-VECTOR CONVERGENCE OVER THE AREA 12Z SUN ONWARD. GFS
SHOWS ABOUT THE SAME THING AS WELL.
THIS PERIOD LOOKS PRETTY WET STARTING WITH SUN AFTERNOON THROUGH MON
NIGHT. WITH SLOW MOVEMENT OF SYSTEM INTO AND THROUGH THE AREA AND
ALSO A WARM FRONT NEAR AND TO THE SOUTH OF THE AREA...THIS SETS UP
THE CWA FOR A WIDESPREAD AND LONG LIVED RAIN EVENT WITH SOME HEAVY
RAIN POSSIBLE. AM FORECASTING ANYWHERE FROM .67 INCH OF QPF OVER THE
SOUTH...TO 1.15 INCHES OVER THE EAST TO OVER 2 INCHES OF RAIN IN THE
FAR WEST NEAR IRONWOOD FROM SUNDAY AFTERNOON THROUGH MONDAY NIGHT
AND THIS DOES NOT SEEM UNREASONABLE WITH PLENTY OF MOISTURE TO THE
SOUTH OF THE AREA AND SLOW SYSTEM MOVEMENT. FOR THIS REASON...BUMPED
POPS UP A BIT TO LIKELY TO CATEGORICAL FOR MOST OF THE CWA THROUGH
THEN. SHOULD SEE SOME SUNSHINE ON SUNDAY. MADE A FEW ADJUSTMENTS TO
TEMPERATURES BASED ON LAKE BREEZES AND WIND DIRECTIONS AND LOWERED
THEM A BIT NEAR THE GREAT LAKES SHORELINES. OTHER THAN THAT...NO
REAL BIG CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB CLOSED LOW AND TROUGH
IN THE NORTHERN AND CENTRAL PLAINS 12Z TUE WHICH MOVE LITTLE INTO
12Z WED. BY 12Z THU...THE TROUGH AND LOW GET PUSHED A BIT FURTHER
EAST TO THE UPPER GREAT LAKES REGION. THE TROUGH AND LOW MOVE
THROUGH BY 12Z FRI WITH RIDGING BUILDING INTO THE PLAINS LATE ON
FRI. SYSTEM WILL BE SLOW TO MOVE THROUGH THE AREA...SO A COUPLE OF
DAYS OF WIDESPREAD RAIN ARE NOT OUT OF THE QUESTION ALONG WITH
COOLER TEMPERATURES WITH GRADUAL SOUTHWARD MOVEMENT OF THE SYSTEM
AWAY FROM THE AREA. THU INTO FRI...THINGS START TO DRY OUT WITH A
COLD FRONT WELL SOUTH OF THE AREA. TEMPERATURES SLIP TO SLIGHTLY
BELOW NORMAL THIS PERIOD. POPS WILL BE HIGHEST IN THE SOUTH CLOSER
TO A WARM FRONT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 141 AM EDT SAT MAY 18 2013
EXPECT VFR CONDITIONS/DRY WX TO PERSIST EARLY IN THE TAF PERIOD. BUT
AS A WARM FNT MOVES IN FM THE S...SOME -SHRA/MVFR CIGS WL BE PSBL...
MAINLY AT CMX/IWD WHERE LLVL WARM/MOIST ADVCTN WL BE MOST
PRONOUNCED. FOLLOWING THE WARM FROPA BY THIS AFTN...EXPECT WSHFT TO
THE S AND A RETURN TO PREDOMINANT VFR WX WITH DAYTIME HEATING/
MIXING. THE ONLY EXCEPTION WL BE AT CMX...WHERE A PERSISTENT UPSLOPE
ESE WIND AND MOISTER LLVL AIR WL RESULT IN LINGERING MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT SAT MAY 18 2013
HEADING THRU EARLY NEXT WEEK...THE PRESSURE GRADIENT OVER THE UPPER
LAKES WILL SLOWLY TIGHTEN BETWEEN LOW PRESSURE SLOWLY MOVING FROM
THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRESSURE
BUILDING IN THE VICINITY OF WRN HUDSON BAY. THIS WILL LEAD TO
EASTERLY WINDS GRADUALLY INCREASING TO ALMOST 30 KNOTS BY MON AND
MON NIGHT...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...07
AVIATION...KC
MARINE...07
AREA FORECAST DISCUSSION
NWS BILLINGS MT
335 AM MDT SAT MAY 18 2013
.SHORT TERM...VALID FOR TDY AND SUN...
RAINFALL TOTALING AN INCH OR MORE STILL LOOKS LIKE A GOOD BET OVER
THE NEXT FEW DAYS IN MANY AREAS. HOWEVER...THE 500-HPA TROUGH THAT
IS SET TO DRIVE ONE OF THE BETTER PRECIPITATION EVENTS WE HAVE HAD
IN A LONG TIME IS SURPRISING COMPLEX...SO SOME UNCERTAINTY EXISTS.
TODAY...THE MID-LEVEL SHORT WAVE TROUGH CENTERED NEAR 700 HPA THAT
IS SEEN ENTERING WESTERN WY ON 09 UTC MOISTURE CHANNEL IMAGES WILL
MOVE INTO SOUTHERN MT. THE ECMWF HAS BEEN THE MOST CONSISTENT WITH
BRINGING THIS BATCH OF FORCING INTO THE AREA IN THE LAST FEW DAYS.
ITS 00 UTC RUN CONTINUES THIS THEME...GENERATING CONVECTION ACROSS
MUCH OF THE AREA AFTER 18 UTC...WITH QPF AMOUNTS OF A QUARTER TO A
HALF INCH. THE 00 UTC GFS HAS FINALLY PICKED UP ON THIS SHORT WAVE
TOO...SO OUR CONFIDENCE IN PRECIPITATION HAS INCREASED ENOUGH THAT
WE HAVE CHOSEN TO ADVERTISE 90 TO 100 PERCENT POPS AFTER 18 UTC IN
THE BILLINGS...SHERIDAN...MILES CITY...AND BROADUS AREAS. THE 700-
500 HPA LAPSE RATES ARE MODEST AROUND 6 C/KM...BUT THERE IS ENOUGH
INSTABILITY /POCKETS OF MUCAPE UP TO 500 J/KG/ TO GENERATE THUNDER
AS WELL. CALIBRATED THUNDERSTORM PROBABILITIES OFF THE 03 UTC SREF
JUMP UP INTO THE 40 AND 50 PERCENT RANGE AFTER 18 UTC AS WELL. THE
SEVERE RISK IS NEGLIGIBLE THOUGH GIVEN THE EXPECTED INSTABILITY. A
CAUTIONARY NOTE ABOUT THE POP FORECAST IS THAT MANY WRF-BASED HIGH
RESOLUTION MODELS FROM 00 UTC CLUSTER CONVECTION FURTHER SOUTHEAST
FROM SHERIDAN TOWARD BROADUS...WHICH MAY ACTUALLY SUPPRESS SOME OF
THE PRECIPITATION FURTHER NORTH IN PLACES LIKE BILLINGS. NOTE THAT
WE ALSO DECIDED TO CARRY ONLY CHANCE POPS IN MANY PLACES BEFORE 18
UTC BASED ON UPSTREAM TRENDS AND RECENT RAP AND HRRR OUTPUT.
TONIGHT...WE CONTINUED LEANING ON THE 00 UTC ECMWF SOLUTION DURING
THE EVENING...WITH A CONCENTRATED AREA OF CATEGORICAL POPS FOR THE
PLAINS OF SOUTH CENTRAL AND SOUTHEASTERN MT BEFORE 06 UTC. WE THEN
LET POPS FALL BACK A BIT AFTER MIDNIGHT IN MANY AREAS SINCE 1/ THE
DIURNALLY-DRIVEN CONVECTION SHOULD DIMINISH WITH SUNSET...AND 2/ A
BREAK IN FORCING SHOULD TAKE PLACE AS THE 700-HPA SHORT WAVE MOVES
OUT AND/OR WEAKENS. IF THE ECMWF IS CORRECT...WE MAY ACTUALLY HAVE
A RELATIVELY DRY PERIOD AFTER 06 UTC. HOWEVER...THE 00 UTC GFS AND
EVEN THE 03 UTC SREF KEEP MORE STRATIFORM-BASED PRECIPITATION OVER
SOUTH CENTRAL MT AND NORTH CENTRAL WY RIGHT THROUGH THE NIGHT...SO
WE WERE CAUTIOUS ABOUT LOWERING POPS BELOW THE LIKELY THRESHOLD AT
THIS POINT. WE ALSO KEPT IN ISOLATED THUNDERSTORMS FOR MOST OF THE
AREA AFTER 06 UTC...BUT WE MIGHT BE ABLE TO DROP THAT MENTION WITH
LATER FORECASTS SINCE MUCAPE AND THE SREF THUNDERSTORM PROBABILITY
VALUES BOTH DWINDLE NOCTURNALLY.
ON SUN...A 500-HPA TROUGH IS EXPECTED TO CLOSE OFF...LIKELY ACROSS
WY...AND THAT SHOULD DRIVE A MORE STEADY RAIN EVENT ACROSS PART OR
EVEN ALL OF THE AREA. THIS IS THE POINT WHERE COMPLEX INTERACTIONS
OF SHORT WAVES AND CONVECTION WITHIN THE LARGER-SCALE TROUGH COULD
ULTIMATELY DICTATE WHERE AND HOW MUCH RAIN FALLS. WE INCREASED THE
POPS ONE MORE TIME THOUGH SO THAT THEY ARE CATEGORICAL FOR MUCH OF
THE AREA SINCE THERE IS FAIR AGREEMENT AMONG 00 UTC MODELS. LIKELY
AND CATEGORICAL POPS CONTINUE INTO SUN NIGHT.
HYDROLOGY-WISE...WE DECIDED TO LET GO OF THE FLASH FLOOD WATCH FOR
THE BURN SCAR AREAS WITH THIS FORECAST RELEASE. THE RAINFALL RATES
OVER THE NEXT FEW DAYS ARE NOT EXPECTED TO BE LARGE ENOUGH TO NEED
AN EXTENSION OF THE WATCH...THOUGH WE WILL CERTAINLY BE KEEPING AN
EYE ON THOSE BURN SCAR AREAS REGARDLESS. OTHERWISE...THERE WILL BE
AT LEAST MINOR RISES ON AREA RIVERS AND STREAMS IN THE COMING DAYS
IF THE FORECAST PRECIPITATION AMOUNTS COME TO FRUITION. HOWEVER...
NO FLOODING IS EXPECTED BECAUSE OUR VERY DRY SOILS WILL BE ABLE TO
EASILY ABSORB MUCH OF THE MOISTURE. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE EXTENDED PERIOD STARTS ON MONDAY AND MODEL DIFFERENCES MUDDY
THE WATERS ON TIMING OF PRECIPITATION TAPERING OFF OVER THE AREA.
BOTH MODELS MOVE THE UPPER LOW THAT WILL IMPACT THE AREA THIS
WEEKEND INTO EASTERN SOUTH DAKOTA BY 00Z TUESDAY. THE GFS BUILDS
THE RIDGE IN MUCH MORE AGGRESSIVELY AND SENDS WRAP AROUND ENERGY
AND MOISTURE SOUTH INTO WYOMING. THE ECMWF...HOWEVER...WAS SLOWER
WITH BUILDING HEIGHTS AND THIS ALLOWS ENERGY TO WRAP BACK INTO
EASTERN AND CENTRAL ZONES MONDAY. WILL SIDE WITH THE ECMWF AS THIS
WAS THE CONSENSUS OF SURROUNDING OFFICES AS OFTEN TIMES THESE
SLOW MOVING UPPER LOWS ARE SLOWER TO DRY OUT THAN MODELS EXPECT.
SHOULD GET DRYING CONDITIONS FOR TUESDAY AS THE RIDGE BUILDS IN
EARNEST. THE NEXT UPPER LOW...WHICH IS PROGGED TO BE QUITE A BIT
DEEPER THAN ITS PREDECESSOR...MOVES INLAND WEDNESDAY. ENERGY DOES
SWING AROUND THE UPPER LOW AND DRIVES ACROSS WESTERN AND CENTRAL
ZONES WEDNESDAY AND THURSDAY. LOW LEVEL WINDS WILL BE EASTERLY AND
THIS SHOULD ALLOW DEWPOINTS TO BE ON THE RISE. DRIER AIR WILL GET
PULLED INTO THE SYSTEM BUT THE GFS HAS BACKED OFF ON THIS FROM
YESTERDAY. CAPES SHOULD INCREASE WITH EASTERLY WINDS INCREASING
LOW LEVEL DEWPOINTS. RAISED POPS OVER WESTERN AND CENTRAL ZONES
FOR AFTERNOON AND EVENING CONVECTION WEDNESDAY AND THURSDAY. WILL
HAVE TO WATCH FOR A POTENTIAL DRY SLOT TO LIMIT CONVECTION...BUT
AS LONG AS THE MODELS KEEP THE WINDS EAST...NEED TO HAVE POPS IN
THERE. TEMPERATURES WILL MODERATE FROM THE LOWER 60S MONDAY TO THE
LOWER 70S TUESDAY AND HOLD AROUND THAT LEVEL THROUGH THE REST OF
THE WEEK. TWH
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS THIS MORNING WILL BECOME MORE
WIDESPREAD BY EARLY AFTERNOON. THE PRECIPITATION WILL MOVE SLOWLY
NORTHEAST AND SHIFT OUT OF THE AREA OVERNIGHT. SOME OF THE STORMS
WILL CONTAIN MODERATE TO BRIEFLY HEAVY RAINFALL AND COULD LOWER
CONDITIONS TO MVFR. PATCHY FOG WILL BE POSSIBLE THIS MORNING EAST
OF A BILLINGS TO SHERIDAN LINE...WITH CONDITIONS DROPPING TO MVFR
LOCALLY. THE FOG WILL LIFT BY LATE MORNING. MOUNTAINS WILL BE
OBSCURED IN SHOWERS AND CLOUDS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 062 048/058 048/062 045/071 047/071 049/071 049/076
+/T 88/T 86/W 31/B 13/T 42/T 22/T
LVM 060 041/057 040/059 037/066 041/071 040/067 041/071
8/T 77/T 85/W 31/B 14/T 43/T 33/T
HDN 064 048/062 047/062 044/071 045/073 049/074 048/078
+/T 98/T 86/W 31/E 12/T 32/T 22/T
MLS 068 051/063 049/062 046/068 046/071 050/071 048/075
+/T +8/T 86/W 53/W 22/T 22/T 22/T
4BQ 069 048/059 047/060 043/063 044/071 048/071 047/075
+/T +8/T 87/W 53/W 11/B 22/T 21/B
BHK 068 048/060 047/060 043/061 043/067 048/067 048/070
8/T +8/T 86/W 53/W 21/B 22/T 22/T
SHR 065 047/056 043/057 040/064 040/073 046/072 045/076
9/T 67/T 86/W 42/W 12/T 32/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
305 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1224 AM CDT SAT MAY 18 2013
MVFR CIGS WILL SPREAD NORTH ALONG HIGHWAYS 83 AND 61 OVERNIGHT.
THESE CIGS SHOULD ERODE TO VFR BY ROUGHLY 17Z-19Z. SCATTERED TO
NUMEROUS THUNDERSTORMS...SOME SEVERE...ARE EXPECTED TO DEVELOP
21Z-23Z AND CONTINUE THROUGH 06Z. STORM DEVELOPMENT WILL COMMENCE
IN THE SOUTH AND SPREAD NORTH.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
430 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
AREA OF SHOWERS AND SCATTERED THUNDERSTORMS CONTINUE TO PUSH
NORTH AND EAST AS A MID LEVEL DISTURBANCE LIFTS NORTHEAST ACROSS
CENTRAL NORTH DAKOTA EARLY THIS MORNING. PRECIPITATION HAS ENDED
AT KBIS-KDIK-KISN...AND WILL END BY 15Z FOR KMOT-KJMS. HIGH LOW
LEVEL MOISTURE WILL RESULT IN AREAS OF FOG AND POSSIBLE VLIFR
STRATUS THIS MORNING AT MOST IF NOT ALL TERMINALS. WHILE THE
STRATUS AND FOG SHOULD LIFT BY MID MORNING...IT MAY LINGER AT KMOT
INTO SATURDAY AFTERNOON...THEN DEVELOP OVER ALL TERMINALS ONCE
AGAIN SATURDAY NIGHT.
SHOWERS AND THUNDERSTORMS WILL REDEVELOP AFTER 18Z SATURDAY
AFTERNOON...DEVELOPING NORTH AND EAST INTO SATURDAY NIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM/LONG TERM...RP KINNEY
AVIATION...NH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1141 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 1141 PM CDT FRI MAY 17 2013
LOWERED TEMPS A BIT IN THE NORTHWESTERN CWA WHERE READINGS HAVE
ALREADY FALLEN INTO THE MID 50S. THINK THAT TEMPS WILL LEVEL OFF
AROUND 50 AS CLOUDS CONTINUE TO INCREASE BUT TEMPS ALREADY AT
FORECAST LOWS. RADAR SHOWS THAT STORMS CONTINUE TO BE ON TRACK TO
ENTER THE SOUTHWESTERN CWA AFTER MIDNIGHT AND CONTINUE
NORTHEASTWARD. SEE LITTLE REASON TO MAKE MORE ADJUSTMENTS TO THE
TIMING OF POPS AT THIS POINT.
UPDATE ISSUED AT 927 PM CDT FRI MAY 17 2013
ADJUSTED POPS/WX BASED ON CURRENT RADAR TIMING. STORMS FIRING
ALONG THE 850MB WARM AIR ADVECTION IN CENTRAL MN WILL CLIP OUR
SOUTHEASTERN COUNTIES...SO INCLUDED A SCATTERED MENTION FOR THE
REST OF THE EVENING. STORMS FIRING OVER WESTERN ND AND SD WILL
MOVE NORTHEASTWARD INTO THE SOUTHERN RED RIVER VALLEY LATER
TONIGHT. IF CURRENT MOTION HOLDS...THE ACTIVITY SHOULD ARRIVE AT
OUR SOUTHERN BORDER AROUND MIDNIGHT AND MOVE NORTHEASTWARD
THROUGHOUT THE EARLY MORNING HOURS. TWEAKED TIMING OF POPS MOVING
INTO THE AREA WITH LIKELY WORDING TRANSITIONING FROM THE SOUTH
JUST AFTER MIDNIGHT TO THE NORTH BY TOMORROW MORNING. ELEVATED CAP
VALUES ARE AROUND 1000 J/KG ACCORDING TO THE SPC MESOANALYSIS.
THINK THAT THE BEST LLJ WILL STAY TO OUR SOUTH BUT SOME ISOLATED
SEVERE HAIL OR WIND IS NOT OUT OF THE QUESTION AROUND THE 06-12Z
TIME FRAME. HOWEVER...CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE IN
THE GRIDS AT THIS POINT SO WILL JUST KEEP GENERAL THUNDER GOING.
UPDATE ISSUED AT 652 PM CDT FRI MAY 17 2013
ADJUSTED POPS ALONG THE CANADIAN BORDER FOR THE NEXT FEW HOURS TO
ACCOUNT FOR THE WEAK SHOWERS/SPRINKLES DEVELOPING IN THAT AREA.
HOWEVER...THE MAIN PRECIP IS WELL TO OUR SOUTH...SO KEPT THE HIGH
POPS RESERVED FOR AFTER MIDNIGHT AS THE GOING FORECAST HAS.
TWEAKED CLOUDS TO INCLUDE CLEARING IN OUR SOUTHWESTERN COUNTIES
BUT THAT WILL NOT LAST LONG AS BLOW OFF FROM CONVECTION FROM OUR
SOUTHWEST BEGINS TO MOVE IN. SHOULD BE TOTALLY CLOUDY AFTER
MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM CDT FRI MAY 17 2013
THE MAIN CONCERNS WILL BE HEAVY RAIN AND SEVERE POTENTIAL. 12Z
MODELS IN DECENT AGREEMENT WITH SYNOPTIC FEATURES...BUT STILL
ENOUGH DIFFERENCES THAT CONFIDENCE IS LOW WITH DETAILS.
WEST COAST TROUGH WILL GRADUALLY PROPAGATE EAST WITH MULTIPLE
SHORTWAVES EJECTING INTO THE REGION. HARD TO PINPOINT EXACTLY WHEN
AND WHERE THE BEST THUNDER CHANCES WILL BE...BUT THE MODELS DO
OFFER A COUPLE STRONGER SIGNALS. THE FIRST BEST CHANCE IS TONIGHT
INTO SATURDAY MORNING AS MENTIONED IN THE PREVIOUS AFD (1243PM).
18Z HRRR DOES INDICATE A THUNDERSTORM COMPLEX MOVING INTO THE
SOUTHERN FA AFTER 06Z...ALONG WITH WITH ISOLATED STRONGER STORMS.
THIS COMPLEX SHOULD MOVE THROUGH FAIRLY QUICKLY...WITH UP TO 0.5
INCH AREAL QPF POSSIBLE.
THINKING THERE WILL BE A BRIEF BREAK IN ACTIVITY ON SATURDAY.
SEVERE POTENTIAL WILL DEPEND ON HOW FAR NORTH THE SURFACE WARM
FRONT WILL MAKE IT BY SATURDAY AFTERNOON. THE GEM/GFS BRING THIS
FEATURE MUCH FURTHER NORTH THAN OTHER MODELS (LIKELY BECAUSE THEY
ARE STRONGER WITH A SHORTWAVE INTO SOUTHERN CANADA). AT ANY
RATE...GIVEN THIS TIME OF YEAR WITHOUT EVAPOTRANSPIRATION...THE
NAM SEEMS TO HAVE THE CORRECT IDEA INDICATING MLCAPE 1000-1500
J/KG WITHIN THE WARM SECTOR. THIS INSTABILITY ALONG WITH DEEP
LAYER SHEAR 30-35 KNOTS SHOULD BE ENOUGH FOR LIMITED SEVERE
POTENTIAL WITHIN THE WARM SECTOR AS THE COLD FRONT SLOWLY
PROPAGATES EAST INTO THE EVENING HOURS.
THE BEST CHANCE FOR FLASH FLOODING POTENTIAL WOULD BE SATURDAY
EVENING AND OVERNIGHT ALONG THE SLOW MOVING BOUNDARY. THE BIGGEST
QUESTIONS AT THIS POINT WILL BE THE EXACT LOCATION OF THIS
FEATURE...AND HOW QUICKLY IT WILL MOVE TO THE EAST. NOT ENOUGH
CONFIDENCE FOR A FLASH FLOOD WATCH AT THIS POINT...BUT THERE IS A
SLIGHT RISK FOR FLASH FLOODING ALONG AND EAST OF THE VALLEY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 PM CDT FRI MAY 17 2013
SUNDAY-MONDAY...UPPER LOW WILL CLOSE OFF JUST SOUTH OF THE FA AND
BRING PERIODIC SHOWERS AND THUNDERSTORMS TO THE REGION.
INSTABILITY IS MUCH WEAKER BY THIS TIME...BUT GIVEN HIGH PWATS AN
ADDITIONAL 1-2 INCHES OF RAINFALL IS POSSIBLE (ESPECIALLY THE
SOUTHERN HALF OF THE FA). THIS RAINFALL WOULD OVER A COUPLE DAYS
AND ANY FLOOD THREAT IS DEPENDENT ON WHAT OCCURS SATURDAY/SATURDAY
NIGHT.
MONDAY NIGHT-FRIDAY...12Z GFS/12Z ECMWF IN PRETTY GOOD AGREEMENT
IN SHOWING THE 500 MB LOW OVER EASTERN SD/MN REGION TUESDAY THEN
DRIFTING A BIT SOUTH AND EAST WEDNESDAY AND THEN EAST OF THE AREA
THURSDAY. LOOK FOR A CONTINUED HIGH THREAT FOR SHOWERS
TUESDAY...DIMINISHING ON WEDNESDAY. A 500 MB RIDGE WILL BUILD IN
BEHIND THE LOW FOR THE END OF THE WEEK WITH DRY WEATHER RETURNING.
LOOK FOR TEMPS TO BIT A BIT BELOW NORMAL WITH THE CLOUDS/RAIN TUE-
WED THEN RETURN TO CLOSE TO NORMAL LEVELS BY LATE WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1141 PM CDT FRI MAY 17 2013
CEILINGS HAVE GONE DOWN TO MVFR AT KFAR AND THE LOWER CONDITIONS
WILL CONTINUE TO SPREAD NORTHWARD THROUGH MUCH OF THE NIGHT.
WEAKENING STORMS WILL ENTER THE FORECAST AREA AFTER
MIDNIGHT...MOVING INTO KFAR AREA AROUND 07-08Z WITH SOME THUNDER
REMAINING AND CONTINUING NORTH AS MOSTLY SHOWERS LATER ON THIS
MORNING. THINK THERE SHOULD BE SOME IMPROVEMENT TO VFR CONDITIONS
ACROSS MOST AREAS DURING THE AFTERNOON ALTHOUGH WILL HAVE TO WATCH
THE NORTHERN SITES WHICH MAY BE ON THE NORTH SIDE OF A WARM FRONT
AND STAY SOCKED IN. KFAR HAS THE BEST CHANCE OF SEEING SOME
CONVECTIVE REDEVELOPENT TOWARDS THE END OF THE PERIOD.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...TG
LONG TERM...TG/RIDDLE
AVIATION...JR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
600 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT ACROSS CENTRAL OHIO WILL DISSIPATE BY
MONDAY AS HIGH PRESSURE WILL HOLDS ALONG THE NEW ENGLAND COAST.
OUR FLOW WILL BECOME MORE SOUTHERLY AND MORE HUMID EARLY IN THE
WEEK AHEAD OF A COLD FRONT FROM THE WEST. THE FRONT SHOULD ARRIVE
LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY MORNING UPDATE...ADJUSTED SOME OF THE HOURLY TEMPERATURES
EARLY THIS MORNING THAT WERE RUNNING A COUPLE OF DEGREES WARMER
THAN FORECAST NEAR THE LAKE ERIE LAKESHORE. WILL HAVE TO WATCH A
FEW SHOWERS COMING NORTH FROM CENTRAL AND SOUTHWEST OHIO THAT
COULD SNEAK INTO THE AREA FROM AROUND MARION TO MOUNT VERNON EARLY
THIS MORNING.
EARLY MORNING ISSUANCE...MOSTLY BETWEEN SYSTEMS THIS
MORNING...WITH THE OVER RUNNING SYNOPTIC CLOUDS AND A FEW
SPRINKLES CLIPPING EASTERN LAKE ERIE AND AREAS EAST OF
PAINESVILLE. TO THE SOUTH THE OLD FRONTAL BOUNDARY IS NEAR
COLUMBUS.
THE ALTOCUMULUS ACROSS PARTS OF THE FORECAST AREA AND THE SPRINKLES
NEAR ERIE WILL THIN AND DISSIPATE EARLY THIS MORNING. THE OLD UPPER
LOW WELL TO OUR SOUTH WILL BEGIN TO LIFT OUT TO THE EAST-NORTHEAST
AND THE OLD FRONTAL BOUNDARY WILL SLOWLY BEGIN TO LIFT NORTH INTO
THE FORECAST AREA TODAY. NOT SURE HOW ACTIVE THE OLD FRONTAL
BOUNDARY WILL BECOME TODAY. THERE SHOULD BE WEAK SUBSIDENCE UNDER
THE BUILDING RIDGE ALOFT AND HIGH CLOUDS WILL SPREAD IN FROM THE
NORTHWEST LATE THIS MORNING. THIS COULD SUPPRESS CONVECTION. WILL
FORECAST RELATIVELY LOW POP...GENERALLY 10-35 PERCENT WITH THE
HIGHEST POP ACROSS THE SOUTH AND DRY (POP LESS THAN 15 PERCENT)
ALONG THE LAKE ERIE SHORE WHERE THE NORTHEAST FLOW OFF THE LAKE
SHOULD KEEP THINGS STABLE.
HIGH TEMPERATURES WILL BE SIMILAR TO YESTERDAY...PERHAPS A DEGREE
OR TWO COOLER AT INLAND LOCATIONS DUE TO THE INCREASE IN CLOUDS. A
COUPLE OF DEGREES WARMER NEAR LAKE ERIE WHERE THE WIND IS NOT OFF
THE WATER THIS MORNING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
AS THE DRY EAST-NORTHEAST FLOW BECOMES SOUTHERLY EARLY IN THE WEEK
WE WILL SEE INCREASINGLY HUMID CONDITIONS. THE OLD FRONTAL BOUNDARY
WILL LIFT NORTH OF THE AREA OR DISSIPATE ON MONDAY. INSTABILITY WILL
INCREASE BUT THERE IS NOT MUCH OF A TRIGGER FOR THUNDERSTORMS UNTIL
TUESDAY INTO WEDNESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE
WEST. WILL CONTINUE WITH A SMALL CHANCE OF SHOWERS/THUNDERSTORMS ON
MONDAY THEN A BETTER CHANCE OF SHOWERS/STORMS TUESDAY INTO
WEDNESDAY. FORECAST HIGHS WILL GENERALLY BE IN THE LOWER AND MID
80S. WITH ENOUGH SUN AND LACK OF SHOWERS COULD EVEN SEE UPPER 80S IN
A FEW LOCATIONS MONDAY OR TUESDAY. NOT AS WARM WEDNESDAY AS
SHOWERS/STORMS SHOULD BE MORE NUMEROUS BY THAT TIME.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
SOME ACTIVE WEATHER FOR THE PERIOD. THE MODELS ARE IN GENERAL
AGREEMENT WITH AN UPPER LOW MOVING ACROSS THE REGION THROUGH THE
PERIOD AND WITH A FRONT MOVING THROUGH THURSDAY AND THURSDAY NIGHT.
THE GFS KEEPS THE UPPER LOW ACROSS THE AREA FRIDAY WHILE THE GFS
MOVES THE LOW OUT. AT THIS TIME CONTINUING A GENERALLY DRY TREND
FRIDAY...EXCEPT KEPT 30 POPS OVER NW PA. USED A BLEND OF THE
GUIDANCE FOR THE TEMPERATURE FORECAST.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
AN IMPULSE ALOFT WAS CAUSE SOME VIRGA OR LIGHT SHOWERS OVER NW PA
AND EASTERN LAKE ERIE EARLY THIS AM...THIS SHOULD DECREASE BY
DAYBREAK. A FRONTAL BOUNDARY WAS STILL WEST TO EAST ACROSS CENTRAL
OHIO. AT THIS TIME THE TEMPERATURE AND DEW POINT SPREAD IS FAIRLY
HIGH AND WITH SOME MID CLOUDS NOT EXPECTING AS MUCH FOG AS LAST
NIGHT. SOME 3SM IS POSSIBLE AT FAVORED LOCATIONS...WITH QUICK DISSIPATION.
OTHERWISE FOR TODAY THE BOUNDARY WILL SLOWLY SHIFT NE TODAY. THE
AIR MASS IS MOIST AT MID LEVELS AND THE LOW LEVEL MOISTURE WILL
INCREASE. THE FLOW WILL REMAIN EASTERLY TODAY AND THAT WILL HELP
KEEP THE THREAT OF SHOWERS AND THUNDERSTORMS REACHING THE
LAKESHORE...WILL KEEP TOL, CLE AND ERI DRY. SOME QUESTION AS TO
THE TIMING OF THE SHOWERS AND THUNDERSTORMS...THE HRRR HAS SOME
SHOWERS AT 14Z NEAR FDY...THIS SEEMS TOO HIGH. THE THREAT OF
SHOWERS AND THUNDERSTORMS SHOULD DECREASE AROUND DARK.
.OUTLOOK...NON VFR POSSIBLE IN PRECIPITATION THROUGH WEDNESDAY.
&&
.MARINE...
A TRICKY LAKE FORECAST WITH THE BOUNDARY OVER CENTRAL OHIO AND HIGH
PRESSURE OVER LAKE ONTARIO. ALL THE MODELS AGREE THE WINDS WILL PICK
UP ON THE LAKE THIS AFTERNOON AND CONTINUE INTO THE EVENING. EARLY
THIS MORNING THE WINDS AND WAVES ARE CLOSE TO SMALL CRAFT ADVISORY
CONDITIONS ON THE WEST END OF THE LAKE. WILL GO WITH A SMALL CRAFT
ADVISORY ON THE WEST END FROM NOON TO MIDNIGHT. THE REST OF THE LAKE
WILL HAVE TO BE WATCHED.
THE WINDS WILL BE MAINLY SOUTHEAST SUNDAY AND BECOME SOUTHWEST FOR
MONDAY THROUGH THURSDAY. THE NEXT THREAT FOR A SMALL CRAFT ADVISORY
WILL BE LATE IN THE WORK WEEK AFTER A COLD FRONT MOVES THROUGH.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO MIDNIGHT EDT TONIGHT
FOR LEZ142>145.
&&
$$
SYNOPSIS...KOSARIK
NEAR TERM...KOSARIK
SHORT TERM...KOSARIK
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
404 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT ACROSS CENTRAL OHIO WILL DISSIPATE BY
MONDAY AS HIGH PRESSURE WILL HOLDS ALONG THE NEW ENGLAND COAST.
OUR FLOW WILL BECOME MORE SOUTHERLY AND MORE HUMID EARLY IN THE
WEEK AHEAD OF A COLD FRONT FROM THE WEST. THE FRONT SHOULD ARRIVE
LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MOSTLY BETWEEN SYSTEMS THIS MORNING...WITH THE OVER RUNNING SYNOPTIC
CLOUDS AND A FEW SPRINKLES CLIPPING EASTERN LAKE ERIE AND AREAS EAST
OF PAINESVILLE. TO THE SOUTH THE OLD FRONTAL BOUNDARY IS NEAR
COLUMBUS.
THE ALTOCUMULUS ACROSS PARTS OF THE FORECAST AREA AND THE SPRINKLES
NEAR ERIE WILL THIN AND DISSIPATE EARLY THIS MORNING. THE OLD UPPER
LOW WELL TO OUR SOUTH WILL BEGIN TO LIFT OUT TO THE EAST-NORTHEAST
AND THE OLD FRONTAL BOUNDARY WILL SLOWLY BEGIN TO LIFT NORTH INTO
THE FORECAST AREA TODAY. NOT SURE HOW ACTIVE THE OLD FRONTAL
BOUNDARY WILL BECOME TODAY. THERE SHOULD BE WEAK SUBSIDENCE UNDER
THE BUILDING RIDGE ALOFT AND HIGH CLOUDS WILL SPREAD IN FROM THE
NORTHWEST LATE THIS MORNING. THIS COULD SUPPRESS CONVECTION. WILL
FORECAST RELATIVELY LOW POP...GENERALLY 10-35 PERCENT WITH THE
HIGHEST POP ACROSS THE SOUTH AND DRY (POP LESS THAN 15 PERCENT)
ALONG THE LAKE ERIE SHORE WHERE THE NORTHEAST FLOW OFF THE LAKE
SHOULD KEEP THINGS STABLE.
HIGH TEMPERATURES WILL BE SIMILAR TO YESTERDAY...PERHAPS A DEGREE
OR TWO COOLER AT INLAND LOCATIONS DUE TO THE INCREASE IN CLOUDS. A
COUPLE OF DEGREES WARMER NEAR LAKE ERIE WHERE THE WIND IS NOT OFF
THE WATER THIS MORNING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
AS THE DRY EAST-NORTHEAST FLOW BECOMES SOUTHERLY EARLY IN THE WEEK
WE WILL SEE INCREASINGLY HUMID CONDITIONS. THE OLD FRONTAL BOUNDARY
WILL LIFT NORTH OF THE AREA OR DISSIPATE ON MONDAY. INSTABILITY WILL
INCREASE BUT THERE IS NOT MUCH OF A TRIGGER FOR THUNDERSTORMS UNTIL
TUESDAY INTO WEDNESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE
WEST. WILL CONTINUE WITH A SMALL CHANCE OF SHOWERS/THUNDERSTORMS ON
MONDAY THEN A BETTER CHANCE OF SHOWERS/STORMS TUESDAY INTO
WEDNESDAY. FORECAST HIGHS WILL GENERALLY BE IN THE LOWER AND MID
80S. WITH ENOUGH SUN AND LACK OF SHOWERS COULD EVEN SEE UPPER 80S IN
A FEW LOCATIONS MONDAY OR TUESDAY. NOT AS WARM WEDNESDAY AS
SHOWERS/STORMS SHOULD BE MORE NUMEROUS BY THAT TIME.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
SOME ACTIVE WEATHER FOR THE PERIOD. THE MODELS ARE IN GENERAL
AGREEMENT WITH AN UPPER LOW MOVING ACROSS THE REGION THROUGH THE
PERIOD AND WITH A FRONT MOVING THROUGH THURSDAY AND THURSDAY NIGHT.
THE GFS KEEPS THE UPPER LOW ACROSS THE AREA FRIDAY WHILE THE GFS
MOVES THE LOW OUT. AT THIS TIME CONTINUING A GENERALLY DRY TREND
FRIDAY...EXCEPT KEPT 30 POPS OVER NW PA. USED A BLEND OF THE
GUIDANCE FOR THE TEMPERATURE FORECAST.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AN IMPULSE ALOFT WAS CAUSE SOME VIRGA OR LIGHT SHOWERS OVER NW PA
AND EASTERN LAKE ERIE EARLY THIS AM...THIS SHOULD DECREASE BY
DAYBREAK. A FRONTAL BOUNDARY WAS STILL WEST TO EAST ACROSS CENTRAL
OHIO. AT THIS TIME THE TEMPERATURE AND DEW POINT SPREAD IS FAIRLY
HIGH AND WITH SOME MID CLOUDS NOT EXPECTING AS MUCH FOG AS LAST
NIGHT. SOME 3SM IS POSSIBLE AT FAVORED LOCATIONS...WITH QUICK DISSIPATION.
OTHERWISE FOR TODAY THE BOUNDARY WILL SLOWLY SHIFT NE TODAY. THE
AIR MASS IS MOIST AT MID LEVELS AND THE LOW LEVEL MOISTURE WILL
INCREASE. THE FLOW WILL REMAIN EASTERLY TODAY AND THAT WILL HELP
KEEP THE THREAT OF SHOWERS AND THUNDERSTORMS REACHING THE
LAKESHORE...WILL KEEP TOL, CLE AND ERI DRY. SOME QUESTION AS TO
THE TIMING OF THE SHOWERS AND THUNDERSTORMS...THE HRRR HAS SOME
SHOWERS AT 14Z NEAR FDY...THIS SEEMS TOO HIGH. THE THREAT OF
SHOWERS AND THUNDERSTORMS SHOULD DECREASE AROUND DARK.
.OUTLOOK...NON VFR POSSIBLE IN PRECIPITATION THROUGH WEDNESDAY.
&&
.MARINE...
A TRICKY LAKE FORECAST WITH THE BOUNDARY OVER CENTRAL OHIO AND HIGH
PRESSURE OVER LAKE ONTARIO. ALL THE MODELS AGREE THE WINDS WILL PICK
UP ON THE LAKE THIS AFTERNOON AND CONTINUE INTO THE EVENING. EARLY
THIS MORNING THE WINDS AND WAVES ARE CLOSE TO SMALL CRAFT ADVISORY
CONDITIONS ON THE WEST END OF THE LAKE. WILL GO WITH A SMALL CRAFT
ADVISORY ON THE WEST END FROM NOON TO MIDNIGHT. THE REST OF THE LAKE
WILL HAVE TO BE WATCHED.
THE WINDS WILL BE MAINLY SOUTHEAST SUNDAY AND BECOME SOUTHWEST FOR
MONDAY THROUGH THURSDAY. THE NEXT THREAT FOR A SMALL CRAFT ADVISORY
WILL BE LATE IN THE WORK WEEK AFTER A COLD FRONT MOVES THROUGH.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO MIDNIGHT EDT TONIGHT
FOR LEZ142>145.
&&
$$
SYNOPSIS...KOSARIK
NEAR TERM...KOSARIK
SHORT TERM...KOSARIK
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
205 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A FRONT ACROSS THE STATE OF OHIO FROM WEST TO EAST WILL REMAIN
NEARLY STATIONARY INTO SATURDAY AND THEN LIFT NORTH AS A WARM
FRONT AND BECOME QUITE DIFFUSE. HIGH PRESSURE WILL REMAIN OFF THE
EAST COAST OVER THE WEEKEND AND PRODUCE A SOUTHERLY FLOW ACROSS
THE REGION INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATED TO REMOVE THE MENTION OF SHOWERS OVER ALL BUT SW OF A MT
VERNON TO FINDLAY LINE. SHOWERS ACROSS CENTRAL OHIO COULD CREEP
INTO THE AREA FOR A BRIEF SHOWER OR TWO. REST OF THE FORECAST FOR
TONIGHT LOOKS REASONABLE.
ORIGINAL DISCUSSION...
A LONE SHOWER HAS DEVELOPED ALONG THE DEWPOINT GRADIENT THIS
AFTERNOON OVER RICHLAND COUNTY AND OTHER ENHANCED CU ARE ALIGNED
FARTHER WEST NEAR FDY. THERE IS SOME WEAK INSTABILITY ALONG AND
SOUTH OF THIS LINE SO WILL INCLUDE A SLIGHT CHANCE OF SHOWERS THIS
EVENING. HAVE USED THE MAV GUIDANCE FOR MIN TEMPERATURES WITH
MINOR CHANGES.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
A WARMER AND INCREASINGLY HUMID WEEKEND IS IN STORE FOR THE FORECAST
AREA AS THE FRONTAL BOUNDARY LIFTS NORTHWARD AND BECOMES DIFFUSE.
HIGHER HUMID WILL MOVE INTO THE REGION ESPECIALLY ON SUNDAY. A
WEAK SHORT WAVE WILL MOVE EAST ACROSS THE LOWER OHIO AND
TENNESSEE VALLEYS AND MAY SPREAD A FEW SHOWERS/STORMS INTO MAINLY
THE SOUTHERN COUNTIES ON SATURDAY AND SATURDAY EVENING BUT
CONFIDENCE AND TIMING IS RATHER UNCERTAIN.
WILL CONTINUE WITH A SLIGHT CHANCE OF SHOWERS/STORMS SUNDAY
AFTERNOON MAINLY OVER THE SOUTHEAST COUNTIES BUT FORCING FOR
ASCENT IS DIFFICULT TO DETERMINE AT THIS TIME SO WILL JUST
INCLUDE A SMALL TO SLIGHT CHANCE OF PCPN.
DRY CONDITIONS ARE EXPECTED SUNDAY NIGHT AND EARLY MONDAY. HAVE
CONTINUED WITH A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS FOR
MONDAY AFTERNOON BUT CONFIDENCE IS LOW.
HAVE USED THE MAV GUIDANCE FOR TEMPERATURES WITH MINOR CHANGES.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE EXTENDED PERIOD WILL BE DOMINATED BY A SURFACE LOW PRESSURE
CENTER JUST TO THE WEST OF THE FORECAST AREA. THIS SYSTEM WILL MOVE
SLOWLY TOWARDS THE REGION THROUGH THE WEEK. INITIALLY ON TUESDAY IT
APPEARS THAT MOST OF THE FORECAST AREA WILL BE IN THE WARM SECTOR AS
THE WARM FRONT WILL BE NORTH OF THE AREA. SHOWERS AND THUNDERSTORMS
ARE NOT OUT OF THE QUESTION IN THIS ENVIRONMENT BUT WITH A LACK OF A
KICKER...THE ACTIVITY SHOULD REMAIN SCATTERED. THE GFS SUGGESTS A
SHORT WAVE SHOULD ROTATE THROUGH THE AREA TUESDAY NIGHT BEFORE THE
ACTUAL COLD FRONT ON WEDNESDAY. WHILE ALL THE PERIODS NEXT WEEK
APPEAR TO BE UNSETTLED WEDNESDAY INTO WEDNESDAY NIGHT APPEAR TO BE
THE TWO PERIODS WITH THE BEST DYNAMICS AND THE GREATEST CHANCE OF
SHOWERS AND THUNDERSTORMS. SHOWERS WILL REMAIN ON THURSDAY AND
THURSDAY NIGHT AS THE LOW PRESSURE SYSTEM PULLS OUT OF THE AREA.
HIGH PRESSURE SHOULD BEGIN TO BUILD OVER THE REGION FRIDAY MORNING
AND SHOULD BRING AN END TO THE PRECIPITATION THREAT.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AN IMPULSE ALOFT WAS CAUSE SOME VIRGA OR LIGHT SHOWERS OVER NW PA
AND EASTERN LAKE ERIE EARLY THIS AM...THIS SHOULD DECREASE BY
DAYBREAK. A FRONTAL BOUNDARY WAS STILL WEST TO EAST ACROSS CENTRAL
OHIO. AT THIS TIME THE TEMPERATURE AND DEW POINT SPREAD IS FAIRLY
HIGH AND WITH SOME MID CLOUDS NOT EXPECTING AS MUCH FOG AS LAST
NIGHT. SOME 3SM IS POSSIBLE AT FAVORED LOCATIONS...WITH QUICK DISSIPATION.
OTHERWISE FOR TODAY THE BOUNDARY WILL SLOWLY SHIFT NE TODAY. THE
AIRMASS IS MOIST AT MID LEVELS AND THE LOW LEVEL MOISTURE WILL
INCREASE. THE FLOW WILL REMAIN EASTERLY TODAY AND THAT WILL HELP
KEEP THE THREAT OF SHOWERS AND THUNDERSTORMS REACHING THE
LAKESHORE...WILL KEEP TOL, CLE AND ERI DRY. SOME QUESTION AS TO
THE TIMING OF THE SHOWERS AND THUNDERSTORMS...THE HRRR HAS SOME
SHOWERS AT 14Z NEAR FDY...THIS SEEMS TOO HIGH. THE THREAT OF
SHOWERS AND THUNDERSTORMS SHOULD DECREASE AROUND DARK.
.OUTLOOK...NON VFR POSSIBLE IN PRECIPITATION THROUGH WEDNESDAY.
&&
.MARINE...
A STALLED FRONTAL BOUNDARY REMAINS LOCKED INLAND KEEPING AN EAST TO
NORTHEAST WIND ACROSS LAKE ERIE TONIGHT. AN AREA OF LOW PRESSURE
MOVING INTO THE OHIO VALLEY SATURDAY AND AN AREA OF HIGH PRESSURE
OVER QUEBEC WILL KEEP AN EASTERLY DOMINANT FLOW OVER THE LAKE. THE
PRESSURE GRADIENT LOOKS UNIMPRESSIVE SO SPEEDS WILL LINGER AROUND
15KT. THE LOW PRESSURE SYSTEM WILL TURN THE WINDS TO THE SOUTHEAST
SATURDAY NIGHT AND INTO SUNDAY WITH SPEEDS UNDER 15 KT ON THE COOLER
WATER. THE FLOW WILL BECOME SOUTHWEST BY TUESDAY. SOME ISOLATED 4 FT
WAVES POSSIBLE IN THE WESTERN BASIN THROUGH SATURDAY...THEN WAVES
1-3 FT THROUGH THE REST OF THE FORECAST.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...LAPLANTE
NEAR TERM...DJB/LAPLANTE
SHORT TERM...LAPLANTE
LONG TERM...GARNET
AVIATION...KIELTYKA
MARINE...JAMISON
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
442 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1112 PM CDT FRI MAY 17 2013
VFR EXPECTED THROUGH THE MAJORITY OF THE TAF PD. THUNDERSTORM
CHANCES RETURN IN THE FINAL FEW HOURS OF THE TAF PD.
LINE OF TSRA WAS OVER HON WITH -RA LINGERING FOR A WHILE AFTER WITH
NO SIGNIFICANT RESTRICTION TO VISIBILITY IN -RA. AFTER THE RAIN
CLEARS NSW THROUGH MOST OF THE REST OF THE HON TAF PD.
SOUTH/SOUTHEAST WIND WILL REMAIN AOA 10KTS AT FSD/SUX THROUGH THE
NIGHT SO HAVE REMOVED PREVIOUS MENTION OF FOG. WIND WONT SHIFT MUCH
IN DIRECTION THRU THE DAY ON SATURDAY BUT SPEED WILL INCREASE WITH
AFTERNOON GUSTS EXPECTED.
IN THE LATTER PART OF THE TAF PD IN THE 02-06Z TIME FRAME...SEVERE
THUNDERSTORMS WILL BE POSSIBLE MOSTLY INVOF FSD/SUX WITH DAMAGING
HAIL AND WIND THE MAIN THREATS. WILL ADD SOME TSRA AT THAT TIME BUT
CONFIDENCE IS ONLY MEDIUM AS FAR AS TIMING AND LOCATION.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...SALLY
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1222 AM CDT SAT MAY 18 2013
.UPDATE...
AVIATION DISCUSSION HAS BEEN UPDATED.
NOT MUCH CHANGE IN THE FORECAST FOR THE TIME BEING. THUNDERSTORMS
HAVE FORMED OVER THE CENTRAL PORTION OF THE STATE AND ARE MOVING
NORTHEAST. STILL EXPECT SOME INCREASE IN COVERAGE AS THE LLJ GETS
CRANKED UP A BIT LATER TNT. HOWEVER QUESTIONABLE WHETHER THERE
WILL BE MUCH IN THE WAY OF SVR THE REST OF THE NIGHT. PERHAPS AN
ELEVATED HAILER OR TWO.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
THE MODELS ALL AGREE WELL AND CONTINUE TO BE VERY CONSISTENT AT
BRINGING THE UPPER LEVEL LOW PRESSURE TROUGH OUT OF THE SOUTHWEST
US THROUGH SUNDAY NIGHT AND CLOSING IT OFF. THUNDERSTORMS ARE
BEGINNING TO DEVELOP IN WESTERN SOUTH DAKOTA LATE THIS AFTERNOON
AND WILL CONTINUE TO DEVELOP AND MOVE EAST INTO CENTRAL AND NORTH
CENTRAL SOUTH DAKOTA THROUGH THE EVENING. THE HRRR MODEL SHOWS
THIS DEVELOPMENT VERY WELL. AS THE LLJ INCREASES INTO THE EVENING
HOURS...EXPECT THIS TREND TO CONTINUE. WITH INSTABILITY INCREASING
ALONG WITH DEEP LAYER SHEAR...SOME SEVERE STORMS ARE POSSIBLE
MAINLY WEST OF THE JAMES VALLEY TONIGHT. THIS FIRST WAVE WILL MOVE
THROUGH WITH MORE DEVELOPMENT EXPECTED SATURDAY AFTERNOON AND
EVENING ACROSS THE CWA. HIGH INSTABILITY WILL BUILD UP AGAIN
SATURDAY AFTERNOON AND EVENING ACROSS THE CWA WHILE ANOTHER SHORT
WAVE TROUGH KICKS OUT OF THE SOUTHWEST UPPER TROUGH. THIS
INTERACTION ALONG A GOOD LOW LEVEL SURFACE BOUNDARY/WARM FRONT ON
SATURDAY AFTERNOON AND EVENING WILL RESULT IN NUMEROUS SHOWERS AND
THUNDERSTORMS AGAIN. SEVERE STORMS LOOK LIKE A GOOD POSSIBILITY
ON SATURDAY AFTERNOON AND EVENING. AS THE MAIN UPPER LEVEL TROUGH
LIFTS INTO THE REGION SUNDAY AND SUNDAY NIGHT AND CLOSES
OFF...SHOWER AND THUNDERSTORM POSSIBILITIES WILL CONTINUE TO BE
VERY GOOD ACROSS ALL OF THE CWA. HEAVY RAIN WILL ALSO BE A THREAT
ACROSS THE CWA AS HIGH PRECIPITABLE WATERS WILL BE AVAILABLE FOR
STORMS.
.LONG TERM...MONDAY THROUGH FRIDAY
DECENT AGREEMENT EXISTS BETWEEN DETERMINISTIC GUIDANCE TO START
THINGS OFF WITH A NEARLY STATIONARY UPPER LOW OVER THE EASTERN
DAKOTAS/MINNESOTA. THIS FEATURE WILL DRIFT SLOWLY TO THE
EAST...WITH WRAP AROUND MOISTURE AND WEAK INSTABILITY LEADING TO
CONSTANT WIDESPREAD SHOWER ACTIVITY...WHICH WILL ALSO RESULT IN
TEMPERATURES BELOW NORMAL FOR MUCH OF THE EXTENDED. ONCE THE UPPER
LOW PUSHES EAST...A COL AREA FORMS OVERHEAD...WITH WEAK
SOUTHEASTERLY LOW LEVEL RETURN FLOW DEVELOPING FOR THE END OF THE
PERIOD...WITH MILDER TEMPERATURES AND LIKELY DRY CONDITIONS.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A LINE OF STORMS IS IMPACTING KABR/KATY. ANOTHER AREA OF STORMS TO
THE WEST MAY AFFECT KMBG TONIGHT AS WELL. WINDS WILL ALSO BE
GUSTY IN AND AROUND THUNDERSTORMS. CONDITIONS ARE EXPECTED TO BE
MAINLY VFR...WITH PERHAPS SOME MVFR CIGS DEVELOPING IN THE MORNING
BEHIND THE STORMS. ANOTHER ROUND OF TSTORMS IS EXPECTED SAT
EVENING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...MOHR
LONG TERM...CONNELLY
AVIATION...SD
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
417 AM CDT SAT MAY 18 2013
.SHORT TERM...
NEAR RECORD TEMPERATURES AND POTENTIAL SEVERE CONVECTION HIGHLIGHT
THE SHORT TERM PORTION OF THE FORECAST.
PRONOUNCED SOUTHWEST FLOW ALOFT IS EVIDENT PER 00Z UPPER AIR
ANALYSIS. SHORTWAVE RIDGING OVER THE PLAINS THAT HAS SHARED SOME
RESPONSIBILITY FOR OUR OPPRESSIVE HEAT WILL SHIFT SLOWLY EAST AS A
TROUGH MOVES ACROSS THE ROCKIES. THIS TROUGH IS TAKING ON SOMEWHAT
OF A NEGATIVE TILT BUT THE STRONGEST WINDS ALOFT REMAIN ON ITS
WESTERN FLANK. A SUBTROPICAL JET STREAK IS PROPAGATING NORTHEAST
ACROSS MEXICO THIS MORNING AND SHOULD ARRIVE THIS EVENING. IN THE
LOWER TROPOSPHERE...STRONG LEE CYCLOGENESIS HAS ENHANCED THE
NOCTURNAL LOW LEVEL JET WHICH IS CONTINUING TO PUMP GULF MOISTURE
NORTH INTO THE SOUTHERN PLAINS. DEWPOINTS ARE IN THE 60S TO LOWER
70S ACROSS THE CWA. THE DRYLINE IS CURRENTLY FOUND TO OUR WEST AND
WILL MOVE A BIT TO THE EAST TODAY. THE QUESTION REMAINS HOW FAR
EAST. MOST OF THE 00Z GUIDANCE MIXES THE DRYLINE AS FAR EAST AS A
HASKELL...TO SAN ANGELO...TO OZONA LINE. HOWEVER...SEVERAL OF THE
HIRES CAMS HOLD THE DRYLINE FARTHER WEST ALONG THE WESTERN BORDER OF
THE CWA. GIVEN THE LACK OF A STRONG MID LEVEL JET ROUNDING THE BASE
OF THE TROUGH THROUGH EARLY AFTERNOON /AND COLLABORATION WITH
NEIGHBORING OFFICES/ I HAVE OPTED FOR THE WESTERN PLACEMENT OF THE
DRYLINE...KEEPING MOST OF THE AREA WITHIN THE MOIST SECTOR.
THE 00Z GUIDANCE SUGGESTS TEMPS WILL BE 5-7 DEGREES COOLER THAN
YESTERDAY. HOWEVER...THE RAP WARMS SURFACE TEMPS UP TO NEAR 105
DEGREES AGAIN. WHILE THE INCREASE IN MID LEVEL CLOUDS AND ADDITIONAL
MOISTURE ON THE EAST SIDE OF THE DRYLINE WILL LIMIT HEATING...I
STILL DO NOT THINK WE WILL COOL OFF BY THAT MUCH. I WENT WITH A
COMPROMISE BETWEEN THE NAM AND RAP...WITH FORECAST HIGHS GENERALLY
97 TO 101 DEGREES. INSTABILITY PARAMETERS ACROSS THE AREA ARE
IMPRESSIVE WITH MLCAPE VALUES OF 2000-3000 J/KG THIS AFTERNOON. DEEP
LAYER SHEAR LOOKS JUST SUFFICIENT FOR SUPERCELLULAR ACTIVITY WITH AN
ANTICIPATED 25-30 KTS OF 0-6KM SHEAR. WITH THE INTENSE SURFACE
HEATING...WE SHOULD SEE SEVERAL UPDRAFTS PENETRATE THE CAP AND
MATURE QUICKLY INTO POTENTIALLY SEVERE THUNDERSTORMS. STEEP MID
LEVEL LAPSE RATES WILL LEND TOWARD A LARGE HAIL THREAT WITH
ADIABATIC LAPSE RATES AND A DEEP...DRY SUB CLOUD LAYER PROVIDING A
WIND THREAT. THE EXTREMELY HIGH CLOUD BASES WILL LIMIT THE TORNADO
POTENTIAL THIS FAR SOUTH...BUT WILL NOT RULE OUT THE THREAT
ALTOGETHER. THE GREATEST POTENTIAL FOR SEVERE WEATHER WILL BE ACROSS
THE BIG COUNTRY WHERE THE CAP WILL BE A BIT WEAKER BUT THE THREAT
WILL EXIST AREAWIDE.
TONIGHT...ANY ONGOING CONVECTION WILL MOVE IN A GENERAL
NORTHEASTERLY DIRECTION AND MAY HANG ON FOR SEVERAL HOURS AFTER
SUNSET GIVEN THE ANTICIPATED INTERACTION OF THE LOW LEVEL
JET...DRYLINE AND INCREASING SYNOPTIC SCALE ASCENT. THE SEVERE
THREAT WILL CONTINUE AS WELL BUT WILL DECREASE ONCE WE LOSE SURFACE
HEATING. EXPECT OVERNIGHT TEMPERATURES TO FALL INTO THE LOWER 70S
FOR THE MOST PART WITH SOUTH WINDS OF 5 TO 15 MPH.
THANKS LUB FOR THE COORDINATION.
JOHNSON
.LONG TERM...
NOT A LOT OF CHANGE NEXT WEEK. KEPT TEMPERATURES ABOVE GUIDANCE
ON SUNDAY...WITH SUBSIDENCE AS THE UPPER TROUGH MOVES EAST. A
LARGE...SLOW MOVING UPPER LOW IS EXPECTED TO DEVELOP OVER THE
CENTRAL AND UPPER MIDWEST EARLY NEXT WEEK. WEST CENTRAL TEXAS
WILL BE SOMEWHAT DRYSLOTTED BEING SOUTH SIDE OF THE UPPER LOW.
HOWEVER...THERE MAY STILL BE ENOUGH LOW LEVEL MOISTURE AROUND TO
GENERATE A FEW THUNDERSTORMS. THE BEST CHANCE OF STORMS IS ON
TUESDAY AS A WEAK COLD FRONT AND UPPER SHORTWAVE MOVE ACROSS THE
REGION. CAN NOT RULE OUT A FEW DRYLINE THUNDERSTORMS ON
MONDAY...AND ON THURSDAY INTO FRIDAY. WILL HOLD OFF MENTION OF
STORMS ON THESE DAYS HOWEVER ...AS RAINFALL POTENTIAL IS FAIRLY
LOW. I AM ALSO CONCERNED WITH UPPER RIDGING TAKING PLACE IN THE
SECOND HALF OF NEXT WEEK...WHICH WOULD ACT TO INHIBIT CONVECTION.
04
&&
.FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS ARE ANTICIPATED TODAY ACROSS MOST
OF WEST CENTRAL TEXAS AS TEMPERATURES WARM TO NEAR 100 DEGREES...
MINIMUM RELATIVE HUMIDITIES FALL TO 20-30 PERCENT AND SOUTH 20 FT
WINDS INCREASE TO AROUND 15-20 MPH. IN ADDITION...ISOLATED AFTERNOON
THUNDERSTORMS WILL BE POSSIBLE WHICH MAY RESULT IN OCCASIONAL CLOUD
TO GROUND LIGHTNING. RELATIVE HUMIDITIES WILL RECOVER TO 70-80
PERCENT OVERNIGHT BUT WILL TANK AGAIN ON SUNDAY AS TEMPERATURES SOAR
TO NEAR OR ABOVE 100 DEGREES YET AGAIN. ON SUNDAY AFTERNOON...THE
DRYLINE WILL MOVE A BIT FARTHER EAST...SPREADING SUB 20 PERCENT
RELATIVE HUMIDITIES AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO
OZONA LINE. SOUTHWEST 20 FT WINDS WILL BE AROUND 15 MPH...RESULTING
IN ELEVATED FIRE WEATHER CONDITIONS. EXPECT CONDITIONS TO IMPROVE
ONLY SLIGHTLY ON MONDAY BUT COOLER TEMPERATURES ARE ANTICIPATED BY
TUESDAY WHICH SHOULD ALLEVIATE FIRE WEATHER CONCERNS TEMPORARILY.
JOHNSON
&&
.CLIMATE...
THE MAX TEMP YESTERDAY IN SAN ANGELO OF 106 DEGREES SMASHED THE
PREVIOUS RECORD OF 100. LIKEWISE...ABILENE SET A NEW RECORD AS
WELL...TOPPING OUT AT 104 AND BESTING THE PREVIOUS MARK OF 101
DEGREES. WE MAY BE IN LINE FOR RECORD HIGH MINIMUM TEMPS THIS
MORNING. THE RECORDS OF 73 DEGREES AT BOTH ABILENE AND SAN ANGELO
MAY FALL AS 2 AM TEMPS ARE STILL IN THE 80S.
THIS AFTERNOON...MAX TEMPS ARE FORECAST TO WARM TO NEAR OR JUST
ABOVE 100 DEGREES. MAX TEMPS RECORDS ARE IN JEOPARDY AT BOTH SITES.
ABILENE HAS A RECORD HIGH TODAY OF 99 DEGREES WHILE SAN ANGELO/S
RECORD IS 102.
JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 100 71 97 69 94 / 20 20 5 10 10
SAN ANGELO 101 72 102 70 96 / 20 10 5 5 5
JUNCTION 97 70 99 71 91 / 10 10 10 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/04
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1148 PM CDT FRI MAY 17 2013
.UPDATE...
SENT OUT A QUICK FORECAST UPDATE TO BUMP UP POPS A BIT FOR AREAS
ALONG AND WEST OF A LINE FROM BOWIE TO LAMPASAS. THE PRIMARY
REASON FOR THIS IS THAT AFTERNOON HIGH RESOLUTION MODEL GUIDANCE
IS MORE AGGRESSIVE WITH ISOLATED THUNDERSTORM INITIATION EAST OF
THE DRYLINE NEAR OUR FAR WESTERN CWA LATE TOMORROW AFTERNOON. THIS
ISOLATED CONVECTION IS INITIATED IN A MODELED ENVIRONMENT
CHARACTERIZED BY 3000 TO 3500 J/KG OF CAPE AND WEAK TO MODERATE
VALUES OF DEEP LAYER BULK SHEAR. THE COMBINATION OF POTENTIAL
ENERGY FOR CONVECTION AND DEEP LAYER SHEAR SHOULD SUPPORT
SUPERCELL THUNDERSTORMS ASSUMING CONVECTION INITIATES AS HIGH
RESOLUTION MODELS ADVERTISE. THERE WILL BE A CAP IN PLACE OVER
MUCH OF NORTH TEXAS...SO ONCE AGAIN THINK THUNDERSTORMS WILL
STRUGGLE TO MOVE EAST OF THIS LINE FROM BOWIE TO LAMPASAS TOMORROW
AFTERNOON OR EVENING. LARGE HAIL AND DAMAGING WINDS WOULD BE THE
PRIMARY HAZARDS...HOWEVER A TORNADO THREAT CANNOT BE RULED OUT.
BACK TO THE CAP...THE 00Z FWD SOUNDING THIS EVENING SHOWED A STOUT
CAP WITH A DEEP DRY ADIABATIC LAYER EXTENDING ABOVE THE CAP FROM
850 MB UP PAST 600 MB. THIS LAYER HAS LAPSE RATES AS STEEP AS OUR
ATMOSPHERE WILL ALLOW AWAY FROM GROUND LEVEL. ANY PRECIPITATION
INTO THIS LAYER OF STEEP LAPSE RATES AND LOW RELATIVE HUMIDITY
WILL ACCELERATE AIR DOWNWARD QUICKLY AS THIS REPRESENTS THE IDEAL
ENVIRONMENT FOR RAIN DROPS TO EVAPORATE...ADDING NEGATIVE
BUOYANCY TO AIR THAT IS ALREADY HEADED TOWARDS THE EARTH. THIS
WILL LIKELY SUPPORT HEAT BURSTS THROUGHOUT THE OVERNIGHT HOURS
WHICH IS WHAT WAS HAPPENED IN COMANCHE EARLIER THIS EVENING. A
LIGHT TO MODERATE ELEVATED RAIN SHOWER MOVED OVER COMANCHE AND
CAUSE THE TEMPERATURE TO CLIMB 4 DEGREES WHILE THE DEW POINT
DROPPED 24 DEGREES AND WINDS GUSTED TO 57 MPH. GRANTED...WE DO NOT
EXPECT MUCH IN THE WAY OF RAIN SHOWER ACTIVITY ACROSS NORTH TX
TONIGHT...BUT THERE IS A WEAK SHORTWAVE TROUGH UPSTREAM...AND IT
WOULD NOT TAKE MUCH OF A RAIN SHOWER TO INITIATE A HEAT BURST. THIS
IS SOMETHING WE WILL BE KEEPING A CLOSE EYE ON THROUGHOUT THE
OVERNIGHT HOURS. NO OTHER SIGNIFICANT CHANGES WERE MADE TO THE
FORECAST.
CAVANAUGH
&&
.AVIATION...
AN UPDATE FROM THE 00Z TAFS...LIGHT RAIN...MOSTLY EVAPORATING
BEFORE REACHING THE GROUND. THIS LIGHT RAIN WAS CAUSING WINDS TO
GUST UP TO 35 TO 40 MPH TO THE NORTHWEST OF THE METROPLEX...AND
WAS PRODUCING ISOLATED CLOUD TO GROUND LIGHTNING STRIKES OVER THE
SAME AREAS. AT THIS TIME IT LOOKS LIKE THE CORE OF THIS LIGHT
ANVIL CLOUD PRECIP WILL REMAIN NORTHWEST OF DFW AIRPORT...BUT WILL
BE WATCHING LOCAL AREA OBS CLOSELY FOR ANY DEVIATION FROM THIS
THINKING. WENT AHEAD AND AMENDED KAFW FOR VCTS AND GUSTY WINDS
FROM 02 TO 03Z DUE TO A RECORDED LIGHTNING STRIKE AROUND HASLET.
THE STORMS OUT WEST ARE BEGINNING TO DISSIPATE...SO THE THREAT FOR
GUSTY WINDS AND ANVIL CLOUD LIGHTNING STRIKES IS EXPECTED TO
DIMINISH THROUGH 04Z AS WELL.
CAVANAUGH
.../PREVIOUS AVIATION DISCUSSION/...
FOR THE 00Z TAFS...TIMING THE ONSET OF MVFR CIGS AND WATCHING FOR
ANY IMPACT TO TAF SITES FROM STORMS OUT WEST ARE THE PRIMARY
FORECAST CONCERNS.
AT THIS TIME...THE CAP ALOFT OVER AREA TAF SITES LOOKS TOO STRONG
TO ALLOW STORMS ONGOING NEAR SAN SABA AND GRAHAM TO MOVE EAST AND
DIRECTLY IMPACT THE INTERSTATE 35 CORRIDOR. STORMS WOULD LIKELY
DISSIPATE BEFORE MINERAL WELLS IF THEY STARTED TO MOVE EAST THIS
EVENING. WILL CONTINUE TO MONITOR THE IMPACT OF THESE STORMS ON
AREA TAF SITES HOWEVER AS ANVIL CLOUDS ARE THICK AND HAVE PRODUCED
LIGHTNING STRIKES AS FAR EAST AS DECATUR THIS EVENING. IF
LIGHTNING LOOKS TO IMPACT LOCAL AREA TAFS THIS EVENING MAY HAVE TO
ISSUE AN AIRPORT WEATHER WARNING FOR DFW AND AMEND TAFS TO MENTION
A THUNDERSTORM WITH NO RAIN. AT THIS TIME...THE PRESENCE OF SOME
HIGHER MID-LEVEL RH PRECLUDES A LARGER THREAT FOR HEAT BURSTS
ASSOCIATED WITH ANVIL CLOUD LIGHT PRECIPITATION.
DID NOT CHANGE THE TIMING OF THE ONSET OF MVFR STRATUS OVER AREA
TAF SITES AT THIS TIME. THE LAMP GUIDANCE IS THE MOST AGGRESSIVE
WITH THIS WITH LESS SUPPORT FROM RAP AND NAM FORECAST SOUNDINGS.
WILL MONITOR UPSTREAM STRATUS DEVELOPMENT TONIGHT AND MAY PULL
STRATUS FROM THE FORECAST BY 06Z IF THERE IS LITTLE UPSTREAM
DEVELOPMENT.
CAVANAUGH
&&
.SHORT TERM...
DRYLINE IS SHARPENING AND IS LOCATED FROM OLNEY TO BRECKENRIDGE
TO BRADY. THE DRYLINE HAS LIKELY REACHED ITS EASTERN MOST
LOCATION...AS A SURFACE LOW INDUCED BY VERY HOT TEMPERATURES IS
DEEPENING NORTH OF ABILENE. THIS HAS CAUSED SURFACE WINDS TO BEGIN
TO BACK TO THE SOUTHEAST ACROSS THE NW CWA...WHICH WILL PULL RICH
LOW LEVEL MOISTURE CHARACTERIZED BY DEWPOINTS NEAR 70 DEGREES BACK
TO THE WEST. THE COMBINATION OF TEMPS NEAR 100 WITH THESE DEWPOINTS
AND NEARLY DRY ADIABATIC LAPSE RATES FROM 500MB TO 850MB HAS
PRODUCED AN EXTREMELY UNSTABLE AIRMASS ACROSS OUR WESTERN ZONES
THIS AFTERNOON. LOCAL OBJECTIVE ANALYSIS IS DEPICTING SBCAPE
AROUND 3500 J/KG...AND POCKETS OF CAPE OVER 4000 J/KG WILL BE
POSSIBLE THROUGH EARLY EVENING. THE STRONG CAP THAT WAS EVIDENT ON
THE MORNING SOUNDING IS CLOSE TO BEING ERODED OVER THE WESTERN
ZONES...OR THE WESTERN 2 COLUMNS OF COUNTIES OF THE CWA. ALONG AND
EAST OF A BOWIE TO GRANBURY TO TEMPLE LINE...OBJECTIVE ANALYSIS
SHOWS CIN WELL ABOVE 200 J/KG AND VIS SATELLITE CONFIRMS THE
PRESENCE OF STRONG CAPPING IN CUMULUS FIELD. WITHOUT UPPER LEVEL
FORCING THIS CAP SHOULD REMAIN...WITH HEATING NOT SUFFICIENT ALONE
TO WEAKEN IT.
CONVECTIVE INITIATION IS NOW OCCURRING SOUTHWEST OF BROWNWOOD AND
CUMULUS IS ORGANIZING TO THE WEST OF BRECKENRIDGE. THIS IS TO
THE WEST OF THE DRY LINE...BUT THIS IS ACTUALLY THE FAVORED
LOCATION FOR UPWARD MESOSCALE FORCING ASSOCIATED WITH DRYLINES.
OFTEN THE LOW MOISTURE CONTENT BEHIND THE DRY LINE IS NOT
SUFFICIENT TO PRODUCE CUMULUS OR PRECIPITATION SO WE CANT SEE THE
LIFT...BUT THIS DRY LINE SEEMS TO HAVE MORE MOISTURE TO WORK WITH.
ONCE THE INFANT UPDRAFTS ARE ADVECTED TO THE MOIST SIDE OF THE DRY
LINE...THEY TAP INTO RICHER MOISTURE AND OFTEN GROW INTO CELLS
THAT RADAR CAN SEE. NEEDLESS TO SAY...CONVECTIVE INITIATION IS A
CERTAINTY AT THIS POINT...BUT COVERAGE OF STORMS WILL BE FAIRLY
LOW DUE TO WEAK UPPER LEVEL FORCING AND THE STRONG CAP. POPS WILL
RANGE FROM 20-40 PERCENT ACROSS THE WESTERN THIRD OF THE CWA.
DEEP LAYER SHEAR IS ON THE LOW SIDE OF WHAT IS TYPICALLY FOUND IN
SUPERCELL ENVIRONMENTS...BUT EXTREME INSTABILITY WILL LIKELY
COMPENSATE. STORM MOTION WILL START OUT EAST BUT AS SUPERCELLS
ORGANIZE AND MATURE THEY WILL LIKELY TURN TO THE SOUTH. THIS
SOUTHWARD MOVEMENT WILL ENHANCE LOW LEVEL STORM RELATIVE
HELICITY...WHICH MAY REACH 150-200 MS/S2 ACROSS THE NW ZONES WHERE
AN ISOLATED TORNADO THREAT IS GREATEST. HOWEVER THE MAIN THREAT
WILL BE GIANT HAIL AND DAMAGING WINDS GIVEN THE EXTREME INSTABILITY
AND LARGE DEWPOINT SPREADS. SPC HAS JUST ISSUED A SEVERE WATCH FOR
THE WESTERN ZONES...AND AGAIN DUE TO THE STRONG CAP AND SOUTHERLY
STORM MOTION BELIEVE ALL SEVERE ACTIVITY WILL REMAIN WEST OF THE
I-35 CORRIDOR. SOME LINGERING AND ELEVATED ACTIVITY MAY IMPACT THE
CENTRAL ZONES LATE TONIGHT...BUT THIS REMAINS A LOW PROBABILITY
AND KEPT POPS OUT OF THE FORECAST.
TR.92
&&
.LONG TERM...
A STRONG CAP WILL REMAIN IN PLACE ACROSS NORTH TEXAS THROUGH
MONDAY...SO THE CONVECTIVE FORECAST WILL HINGE ON WHETHER FORCING
FROM THE DRY LINE OR UPPER LEVEL SHORTWAVES WILL BE PRESENT. THE
DRYLINE WILL HEAD FARTHER WEST SATURDAY...AND ALTHOUGH A WELL
DEFINED SHORTWAVE MOVES ACROSS THE REGION...BELIEVE STORM
INITIATION WILL BE WELL NW OF THE CWA. A FEW OF THESE CELLS MAY
TRACK INTO THE NORTHWESTERN PARTS OF THE CWA SATURDAY
EVENING...BUT WILL KEEP POPS LOW AND AT 20 PERCENT. ON SUNDAY THE
DRY LINE WILL MIX EAST AGAIN AND FLIRT WITH THE NW CWA...AND HAVE
POPS A LITTLE HIGHER...BUT STILL PRIMARILY OVER THE NW ZONES IN
THE AFTERNOON. SINCE THE TAIL END OF THE PLAINS TROUGH WILL PASS
THROUGH THE NORTHERN ZONES SUNDAY NIGHT...CONVECTION MAY SURVIVE
PAST SUNSET AND TRACK ACROSS THE AREA NORTH OF I-20. EXPECT THE
SAME PATTERN ON MONDAY AND POPS ARE SIMILAR TO SUNDAYS. GIVEN THE
INSTABILITY AND SHEAR PROFILES SEVERE STORMS ARE POSSIBLE WITH ANY
ACTIVITY SATURDAY THROUGH MONDAY. FOR TEMPERATURES...SATURDAY WILL
BE THE WARMEST DAY WITH HIGHS IN THE 90S MOST AREAS...BUT WINDS
WILL INCREASE A BIT SUNDAY AND MONDAY WHICH SHOULD SHAVE A COUPLE
DEGREES...WITH HIGHS IN THE UPPER 80S EAST TO MID 90S WEST. LOWS
WILL REMAIN MUGGY AND IN THE LOW-MID 70S...WITH TONIGHT THE
COOLEST DUE TO FEWER CLOUDS AND LIGHTER WINDS.
ON TUESDAY ANOTHER LOBE OF ENERGY WILL ROTATE AROUND THE PLAINS
TROUGH AND HELP PROPEL A WEAK COLD FRONT SOUTH INTO THE AREA. THE
FRONT/DRYLINE COMBINATION WILL REACH THE NW CWA AND BECOME A FOCUS
FOR CONVECTION BY TUESDAY AFTERNOON. STRONG FORCING ASSOCIATED
WITH THE UPPER SHORTWAVE TROUGH WILL ENHANCE LIFT...AND EXPECT
SCATTERED CONVECTION TO OCCUR TUESDAY AFTERNOON AND WORK
SOUTHEAST ACROSS THE AREA. HAVE BUMPED POPS UP TO CHANCE AS THIS
WILL BE THE BEST DAY FOR RAIN CHANCES. AGAIN...THERE IS A SEVERE
WEATHER THREAT WITH THIS CONVECTION AS WELL.
THE FRONT WILL NOT BE VERY STRONG...AND WINDS MAY NOT SPEND MUCH
OR ANY TIME FROM THE NORTH...BUT THE AXIS OF BEST MOISTURE AND
INSTABILITY SHOULD GET PUSHED SOUTHEAST OF THE AREA. WILL KEEP A
SLIGHT CHANCE OF CONVECTION WEDNESDAY...BUT THIS ACTIVITY IS NOT
EXPECTED TO BE VERY SIGNIFICANT. TEMPS WILL BE A LITTLE COOLER AS
HEIGHTS LOWER...AND THE SLIGHTLY DRIER AIR WILL HELP LOWS FALL TO
NEAR NORMAL. HAVE KEPT THE REMAINDER OF THE FORECAST DRY AS UPPER
LEVEL RIDGING BUILDS INTO THE AREA...WHICH IS WELL AGREED UPON BY
EXTENDED GUIDANCE.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 92 72 90 72 / 10 5 5 10 20
WACO, TX 70 92 72 91 73 / 10 5 5 10 10
PARIS, TX 69 88 70 87 68 / 10 10 5 5 20
DENTON, TX 70 93 72 90 72 / 10 10 10 10 30
MCKINNEY, TX 69 90 71 89 71 / 10 5 5 5 20
DALLAS, TX 73 93 74 91 74 / 10 5 5 10 20
TERRELL, TX 69 90 70 91 71 / 10 5 5 5 10
CORSICANA, TX 70 90 70 89 73 / 10 5 5 5 10
TEMPLE, TX 69 92 71 91 72 / 20 10 5 10 10
MINERAL WELLS, TX 71 96 69 94 70 / 20 10 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
MORE AMPLIFIED PATTERN THIS PERIOD AS WESTERN TROF DIGS SOUTHEAST
AND CUTS OFF OVER THE CENTRAL PLAINS. BUILDING HEIGHTS OVER STATE
TODAY AS RIDGE MOVES EAST ACROSS STATE THIS PERIOD WILL LEAD TO
LESSENING CHANCE OF PCPN TODAY. LOCAL RADARS CURRENTLY SHOWING
ISOLD TO SCATTERED SHOWERS OVER NORTHERN WI. TO THE WEST...AREA OF
THUNDERSTORMS MOVING THROUGH MN AND FAR WESTERN WI NORTH OF
STATIONARY/WARM FRONT AND AHEAD OF VORT EJECTING OUT OF UPPER
TROF. MOST TEMPERATURES REMAIN IN THE LOWER 50S AT THIS TIME GIVEN
CLOUDS AND EAST FLOW.
AGAIN...FOCUS OF FORECAST ON PCPN CHANCES AND TEMPS. SHOWERS OVER
NORTHERN WI NORTH OF 850H BAROCLINC ZONE...AREA OF SIG WAA. HAVE
TRENDED TOWARDS A BLEND OF NAM AND EC...AND MESO HRRR MODELS. ALL
SUGGEST PCPN TO SHIFT NORTH THIS MORNING...LEAVING MUCH OF CWA DRY
THIS AFTERNOON. HAVE KEPT A BUFFER OF CHANCE POPS OVER WEST.
RIDGE AXIS PASSES OVERHEAD TONIGHT. HAVE STAYED WITH DRY FORECAST.
ON SUNDAY...PCPN CHANCES INCREASE THROUGH THE DAY AS RIDGE TO BE
EAST OF STATE AND DYNAMICS WITH UPPER TROF COME IN TO PLAY.
STRENGTHENING LLVL FLOW (30 TO 35 KTS AT 850) STRAIGHT OUT OF GULF
TO BRING PW VALUES TO 1.5 INCHES OR GREATER. INSTABILITY INCREASES
WITH MID LEVEL LAPSE RATES AT 7. EC SUGGESTS CAPE VALUES AROUND
1K...NAM SHOWING NORMAL HIGH BIAS. THOUGH MODEL SOUNDINGS SHOW
STRONG CIN OVER EAST THROUGH DAY. HAVE STAYED DRY EAST THROUGH THE AFTN.
TEMPS TO BE A HEADACHE AGAIN TODAY WITH CLOUDS...ONGOING PCPN AND
EAST FLOW OFF LAKE. DID NOT STRAY TOO FAR FROM PREVIOUS FORECAST.
WENT A BIT HIGHER ON CLOUDS GIVEN PLENTY OF CIRRUS FLOWING THIS
WAY FROM UPSTREAM CONVECTION. STAYED WITH TEMPS HITTING 80 ON SUN
AS BEST PERFORMING GUIDANCE SUGGESTS...THOUGH UNCERTAINTY SIG
GIVEN POSSIBLE CONVECTION.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
PRECIPITATION CHANCES FOR MUCH OF THE UPCOMING WEEK ARE THE MAIN
CONCERNS DURING THIS PART OF THE FORECAST.
THUNDERSTORMS LOOK LIKE A PRETTY GOOD BET ACROSS THE AREA ON
SUNDAY NIGHT WITH SHORT WAVE ENERGY PASSING THROUGH...AN
APPROACHING SURFACE LOW AND A FRONTAL BOUNDARY MOVING NORTHEAST
ACROSS THE AREA. THOUGH EASTERLY COMPONENT OF SURFACE FLOW OFF
LAKE MICHIGAN MAY LESSEN THE CHANCES FOR STORMS IN THE EAST.
HAVE LIKELY POPS FOR MONDAY AND MONDAY NIGHT. SPC DAY 3 OUTLOOK
HAD CENTRAL AND EAST CENTRAL WISCONSIN IN SLIGHT RISK AS A SURFACE
LOW APPROACHES AND A CLOSED 500MB CYCLONE MAKES ITS WAY TOWARD THE
STATE. STILL QUITE A BIT OF UNCERTAINTY REGARDING THIS SEVERE
THREAT.
THE SURFACE LOW SHOULD MAKE ITS WAY INTO WESTERN WISCONSIN ON
TUESDAY AS BOTH THE SURFACE AND UPPER LEVEL SYSTEMS MAKE THEIR WAY
ACROSS THE WESTERN GREAT LAKES REGION. THUNDER CHANCES SHOULD
DIMINISH AS THE SYSTEMS PASS EAST OF THE FORECAST AREA AND THE
CHANCE OF SHOWERS SHOULD FINALLY COME TO AN END BY THE END OF THE
WORK WEEK.
TEMPERATURES AT THE START OF THE PERIOD ARE EXPECTED TO BE ABOVE
NORMAL BUT COOLER TEMPERATURES ARE FORECAST FOR THE REST OF THE
WEEK...WITH HIGHS MAINLY IN THE 60S EACH DAY.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1025 PM CDT FRI MAY 17 2013
MVFR CIGS OVERNIGHT ACROSS CENTRAL AND NORTH...WITH OCNL IFR IN
CENTRAL WI. IN ADDITION...AREAS OF FOG MAY DEVELOP WHICH COULD DROP
VSBYS BLO 3 MILES FROM TIME TO TIME BETWEEN 07Z AND 12Z. ISOLATED
STORM NOT OUT OF THE QUESTION...BUT BEST CHANCE WILL BE WEST.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......JKL
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
400 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT MAY 18 2013
UPPER LEVEL RIDGING TAKING PLACE ACROSS THE UPPER MIDWEST TODAY AS
THE WESTERN CONUS TROUGH DEEPENS. PLENTY OF CONVECTION FIRING UP OFF
THE 850 MB LLJ IN CONJUNCTION WITH A PASSING SHORTWAVE ACROSS
CENTRAL MINNESOTA BACK INTO THE DAKOTAS. THIS ACTIVITY WILL MOSTLY
REMAIN NORTH/NORTHWEST OF THE FORECAST AREA...HOWEVER COULD CLIP
PORTIONS OF NORTH CENTRAL WISCONSIN BY MID TO LATE MORNING. LATEST
RUNS OF THE HRRR AND RAP SHOW CONVECTION WANING BUT POSSIBLY
IMPACTING TAYLOR AND CLARK COUNTIES IN WISCONSIN SO HAVE MAINTAINED
SHOWER/STORM CHANCES THERE. MOIST EASTERLY FLOW AND DECAYING
CIRRUS WILL KEEP SKIES MOSTLY CLOUDY TO OVERCAST THIS
MORNING...BUT AS THE MCS LIFTS NORTH...IT WILL PULL THE WARM FRONT
THROUGH THE AREA. PARTLY TO MOSTLY SUNNY SKIES WILL MOST LIKELY BE
SEEN ACROSS NORTHEAST IOWA WHERE THE FRONT IS ABLE TO CLEAR
THROUGH THE MOST.
DECENT INSTABILITY EXPECTED TODAY IN THE WARM SECTOR...AND MUCAPE
VALUES RANGE FROM 1000 TO 2000 J/KG IN A WEAKLY CAPPED ENVIRONMENT.
LACK OF SURFACE CONVERGENCE HOWEVER PRECLUDES HIGHER PRECIPITATION
CHANCES BUT MOST OF THE DETERMINISTIC AND PROBABILISTIC GUIDANCE
HINTS THAT CENTRAL WISCONSIN COULD SEE A STRAY SHOWER OR
THUNDERSTORM THIS AFTERNOON. HAVE MAINTAINED PRECIPITATION CHANCES
THERE. OTHERWISE...A WARM DAY ON TAP WITH LOWER TO MID 80S EXPECTED
SOUTH OF I-94.
RELATIVELY QUIET CONDITIONS TONIGHT AS CONVECTION IS EXPECTED TO
REMAIN WELL TO THE WEST AND NORTH. MILD NIGHT WITH SOUTHERLY
FLOW...AND OVERNIGHT LOWS IN THE UPPER 50S TO LOWER 60S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT MAY 18 2013
FOCUS IS ON SEVERE WEATHER CHANCES SUNDAY AND MONDAY AS ACTIVE
WEATHER PATTERN SETS UP ACROSS MUCH OF THE CENTRAL PLAINS.
UPPER LEVEL NEGATIVE TILTED SHORTWAVE TROUGH EJECTS INTO THE CENTRAL
PLAINS ON SUNDAY...MEANWHILE AT THE SURFACE A FEW WAVES OF LOW PRESSURE
SHOULD BE DEVELOPING ACROSS OKLAHOMA INTO NEBRASKA. THIS WILL PULL
NORTH AMPLE GULF OF MEXICO MOISTURE...WITH PWATS INCREASING FROM
AROUND 1 INCH...TO NEARLY 1.75 INCHES...OR 175 PERCENT OF NORMAL.
SURFACE DEWPOINTS WILL RISE INTO THE LOW TO MIDDLE 60S. THERE SHOULD
BE CONVECTION ACROSS WESTERN IOWA INTO SOUTHWEST MINNESOTA EARLY
SUNDAY MORNING...WHICH WILL BE FEEDING OFF THE 850 MB LLJ. THIS
SHOULD WEAKEN AS IT APPROACHES THE WESTERN FORECAST AREA BUT GOOD
CONSENSUS THAT SHOWERS AND THUNDERSTORMS WILL BE AROUND IN THE
MORNING HOURS. THEN...THE BIG QUESTION BECOMES HOW MUCH CLEARING
WE WOULD SEE TO AID IN DESTABILIZATION. ASSUMING WE CLEAR
OUT...0-3KM MUCAPE IS EXPECTED TO INCREASE TO 1500-2000
J/KG...HIGHEST TO THE SOUTH AND WEST. OVERALL THE SHEAR PROFILES
ARE LESS IMPRESSIVE...BUT STILL SHOW 0-3KM BULK SHEAR OF NEARLY 30
KTS. THE ATMOSPHERE DOES REMAIN UNCAPPED SO EXPECTING GOOD CHANCES
OF CONVECTIVE INITIATION WITH ORGANIZED STORMS IN THE FORM OF
SUPERCELLS OR POSSIBLY BOWING SEGMENTS. STRONG TO SEVERE STORMS
WOULD DEVELOP ACROSS WESTERN INTO CENTRAL IOWA...AND TRACK
EAST/NORTHEAST THROUGH THE EVENING HOURS. THE PRIMARY THREATS ARE
LARGE HAIL AND DAMAGING WINDS. THE ENVIRONMENT STILL SUPPORTS AN
ISOLATED TORNADO...HOWEVER DEPENDING WHERE A WARM FRONT LAYS IS
MORE UNCERTAIN. 18.00Z GFS HAS THIS BOUNDARY ACROSS CENTRAL
IOWA...BUT 18.00Z ECMWF/NAM HINT THIS COULD BE FURTHER SOUTH.
THE WHOLE SYSTEM EDGES EASTWARD MONDAY...WITH THE BOTH THE
SURFACE AND UPPER LEVEL LOW BECOMING STACKED NEAR SIOUX FALLS SD
BY 12Z MONDAY. PIECES OF ENERGY WILL BE ROTATING THROUGH SOUTHERN
BEND OF THIS TROUGH...LIFTING THROUGH THE AREA DURING THE DAY. THE
SYNOPTIC SETUP IS SLIGHTLY MORE FAVORABLE FOR SEVERE WEATHER FOR
PARTS OF THE AREA. THE SHEAR PROFILES ARE MORE IMPRESSIVE WITH
0-6KM BULK SHEAR VALUES 40 TO 50 KTS ACROSS EASTERN IOWA INTO
SOUTHERN WISCONSIN. THE MORE LIMITING FACTOR THIS DAY IS HOW MUCH
DESTABILIZATION WILL OCCUR. THERE COULD BE SCATTERED SHOWERS AND
PLENTY OF CLOUDS AROUND TO LIMIT INSTABILITY. IF WE CAN BREAK OUT
AND FULLY DESTABILIZE...THEN 0-3KM MUCAPE MAY REACH 1500 TO 2000
J/KG. THE ENVIRONMENT SHOULD SUPPORT DISCRETE STORM CELLS...WITH
THE THREATS AGAIN LARGE HAIL AND DAMAGING WINDS.
TUESDAY AND BEYOND...THE UPPER LOW REMAINS NEARLY STATIONARY ACROSS
THE UPPER MIDWEST. THIS GIVES PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS ACROSS THE ENTIRE AREA TUESDAY-THURSDAY. MODEL
CONSENSUS PAINTS 30 TO 60 PERCENT CHANCES WHICH IS APPROPRIATE AT
THIS TIME. FEEL THAT MUCH OF NEXT WEEK COULD BE UNSETTLED BUT SEE
LITTLE OPPORTUNITY TO PROVIDE MORE DETAILS IN WHAT PERIODS WOULD BE
MORE ACTIVE...SINCE TIMING PIECES OF ROTATING AROUND THE UPPER LOW
IS DIFFICULT THIS FAR OUT. THE BIGGER STORY WOULD BE THE HEIGHTENED
RISK FOR EXCESSIVE RAINFALL AND LOCALIZED FLOODING IF REPEATED
ROUNDS OF CONVECTION DO IMPACT THE AREA. BY MID-WEEK...SOILS WOULD
BECOME EVEN MORE SATURATED...AND FLASH GUIDANCE FURTHER REDUCED. SEE
HYDROLOGY SECTION BELOW FOR MORE DETAILS ON THAT RISK.
TEMPERATURE-WISE...WARMEST DAYS LOOK TO BE SUNDAY AND MONDAY BEFORE
A GRADUAL COOL DOWN TUESDAY...THEN TO BELOW NORMAL READINGS
WEDNESDAY THROUGH THURSDAY AS THE UPPER LOW DRIFTS OVERHEAD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1203 AM CDT SAT MAY 17 2013
GOES SATELLITE IMAGERY SHOWING A LARGE CONVECTIVE COMPLEX WITH
MASSIVE CIRRUS SHIELD HEADING OVER THE TAF SITES AFTER 06Z.
OBSERVATIONS OF CEILINGS ARE SHOWING INCREASING MIDLEVEL CLOUD
COVER NORTH OF THE TAF SITES WITH ERODING LOW-LEVEL IFR CIGS
NORTHWESTWARD. THIS IS THE OPPOSITE OF THE CURRENT TRENDS AT THE
TAF SITES WHICH HAVE IFR BUILDING IN OVERNIGHT.
THE HI RES RAPID REFRESH GUIDANCE CEILING FORECAST...WHICH SEEMS
TO HANDLE THE CURRENT SITUATION AND TREND VERY WELL...CONTINUES TO
ERODE THE IFR CIGS NORTHWEST AND AWAY FROM THE TAF SITES. HOWEVER...THE
TEMP/DEW POINT SPREADS ARE ONLY A FEW DEGREES...ESPECIALLY AT
KRST...THUS ANY COOLING MAY SATURATE THAT CLOUD LAYER.
A SLOW APPROACH TO AN IMPROVEMENT IN THE FORECAST SEEMS PRUDENT.
THUS...HAVE DELAYED ONSET OF IFR FOR THE 06Z TAFS. WILL CONTINUE TO
MONITOR THE TRENDS...BUT IFR MAY BE REMOVED FROM THE FORECAST IN
THE NEXT SEVERAL HOURS.
&&
.HYDROLOGY...SUNDAY AND INTO NEXT WEEK
ISSUED AT 400 AM CDT SAT MAY 18 2013
HEAVY RAINFALL /2 TO 2.5 INCHES/ FELL FRIDAY ACROSS PORTIONS OF
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...AND COMBINED WITH A RECORD
WET METEOROLOGICAL SPRING...RESULTS IN AN INCREASED RISK FOR
LOCALIZED FLASH FLOODING AS WE HEAD INTO THE LATTER PART OF THE
WEEKEND AND MUCH OF NEXT WEEK. PERIODS OF SHOWERS AND THUNDERSTORMS
LOOK TO IMPACT MUCH OF SOUTHEAST MINNESOTA AND NORTHEAST BEGINNING
SUNDAY AFTERNOON. AN ADDITIONAL 1 TO 3 INCHES IS POSSIBLE...AND IF
THIS FALLS IN A SHORT PERIOD...LOCALIZED FLASH FLOODING WOULD OCCUR.
THE 1 AND 3 HOUR FLASH GUIDANCE REMAINS WELL BELOW NORMAL...AND IS
GENERALLY LESS THAN 1 AND 2 INCHES...RESPECTIVELY. WPC CONTINUES THE
SLIGHT RISK OF EXCESSIVE RAINFALL AND FLASH FLOODING EARLY NEXT WEEK
ACROSS MUCH OF CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. A FLASH
FLOOD WATCH MAY BE NECESSARY FOR PORTIONS OF THE AREA.
STREAMS...CREEKS...AND RIVERS HAVE RESPONDED TO THE RECENT
RAINFALL...MOSTLY WITHIN BANK RISES. HOWEVER...REPEATED ROUNDS OF
HEAVY RAIN COULD PUSH SOME OF THE MORE FLASHY BASINS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA TO NEAR FLOOD STAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...BAUMGARDT
HYDROLOGY...ZT
AREA FORECAST DISCUSSION
NWS PUEBLO CO
419 AM MDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 418 AM MDT SAT MAY 18 2013
FIRE WEATHER CONDITIONS ARE THE MAIN CONCERN FOR TODAY. AN UPR TROF
WL BE OVR THE GREAT BASIN TODAY AND WL MOVE INTO WRN CO BY EVENING
AND THEN WL BE MOVING ACRS THE STATE OVERNIGHT. AHEAD OF THE UPR
TROF...W TO SW WINDS SFC WINDS WL INCREASE TODAY WITH MOST AREAS
BEING BREEZY TO WINDY. DEW POINT FORECAST IS A BIT DIFFICULT...BUT
WL LEAN TOWARD THE HRRR FORECAST WHICH IS DRIER THAN THE NAM12 AND
THE RAP13. HIGH TEMPS TODAY SHOULD BE A LITTLE COOLER THAN
YESTERDAY...BUT STILL ABOVE NORMAL OVER THE ERN AREAS AND AROUND
NORMAL FOR THE SAN LUIS VALLEY. THE RED FLAG WARNING FOR BACA AND
EASTERN LAS ANIMAS COUNTIES STILL LOOKS GOOD...BUT IT NOW LOOKS LIKE
MIN RH VALUES AND WINDS MAY MEET RED FLAG CRITERIA FOR A LONG
ENOUGH PERIOD OVER MUCH OF THE SAN LUIS VALLEY AND OVER SRN EL PASO
COUNTY WHERE THE FUELS ARE DRY...AND THUS WL ADD THESE AREAS TO THE
RED FLAG WARNING.
BY LATE MORNING THERE WL PROBABLY BE SOME ISOLD SHOWERS/TSTMS OVR
THE MTS...WITH BEST CHANCES BEING ALONG THE CONTDVD. PCPN CHANCES
SHOULD THEN INCREASE OVR THE MTS AND HIGH VALLEYS IN THE AFTERNOON.
THE DRY LINE IS EXPECTED TO PUSH EAST INTO KS WITH THE SERN PLAINS
REMAINING DRY. THE NAM12 HAS SOME PCPN DEVELOPING OVR THE FAR SERN
PLAINS THIS AFTERNOON...BUT BELIEVE THAT THE DEW POINTS IN THE NAM
ARE TOO HIGH. HOWEVER THERE IS A CHANCE THAT WE COULD SEE SOME TSTM
DEVELOPMENT OVR ERN PORTIONS OF KIOWA COUNTY WHERE THE HIGHEST DEW
POINTS WL LIKELY BE...SO WL KEEP SOME ISOLD POPS IN THAT AREA. SPC
HAS THE FAR ERN PORTIONS OF KIOWA COUNTY IN THE SLIGHT RISK AREA FOR
TODAY. CHANCES FOR SHOWERS/TSTMS CONTINUE OVR AND NR THE HIGH
COUNTRY THIS EVENING...WITH LITTLE CHANCE FOR PCPN OVR THE SERN
PLAINS. SFC WINDS THIS EVENING WL BE WESTERLY AND BREEZY MOST AREAS
AND THEN WL BECOME MORE NWRLY BY LATE NIGHT. MOST AREAS SHOULD BE
DRY BY LATE NIGHT...BUT THE CENTRAL MTS WL PROBABLY CONTINUE TO SEE
A FEW SHOWERS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 418 AM MDT SAT MAY 18 2013
SUNDAY-MONDAY NIGHT...MODELS CONTINUE TO INDICATE A COOL AND
GENERALLY UNSETTLED WEATHER PATTERN ACROSS THE AREA WITH A BROAD
UPPER TROUGH IN PLACE ACROSS THE INTERMOUNTAIN WEST THROUGH THE HIGH
PLAINS...ALONG WITH SEVERAL EMBEDDED SHORT WAVES TRANSLATING ACROSS
THE ROCKIES THROUGH THE PERIOD. FIRST WAVE ACROSS SOUTH CENTRAL
COLORADO EARLY SUNDAY MORNING CONTINUES TO TRANSLATE OUT ACROSS THE
SOUTHEAST PLAINS AND INTO WESTERN KANSAS SUNDAY AFTERNOON KEEPS THE
CHANCE FOR ISOLATED TO SCATTERED SHOWERS ACROSS THE AREA SUNDAY
MORNING AND AFTERNOON. MODELS CONTINUE TO INDICATE MAINLY HIGH BASED
STORMS WITH CONTINUED INVERTED V PROFILES...SAVE THE FAR SE PLAINS
WHERE LOW LEVEL MOISTURE FILTERS BACK INTO THE AREA FROM WESTERN
KANSAS WITH NORTHERLY FLOW BEHIND A BACKDOOR COLD FRONT MOVING
ACROSS EASTERN COLORADO.
NEXT SHORT WAVE DIGGING INTO NORTHWESTERN COLORADO LATE SUNDAY NIGHT
CONTINUES TO SLOWLY LIFT OUT ACROSS THE STATE THROUGH MONDAY NIGHT.
THIS PERIOD STILL LOOKS TO BRING THE BEST CHANCES OF WETTING
RAINFALL ALONG WITH ANOTHER LATE SEASON SHOT OF HIGHER ELEVATION
SNOWFALL...AS H7 TEMPS PROGGED TO DROP TO BETWEEN 0C AND 4C. WITH
THAT SAID...MONDAY STILL LOOKS TO BE THE COOLEST DAY OF THE UPCOMING
WEEK WITH POTENTIAL FOR SUB FREEZING OVERNIGHT LOWS ACROSS THE HIGH
MT VALLEYS SUNDAY NIGHT AND MONDAY NIGHT.
TUESDAY-WEDNESDAY...SLOW WARMING TREND ON TAP WITH BRISK NORTHWEST
FLOW ALOFT ACROSS THE AREA TUESDAY MODERATING THROUGH WEDNESDAY AS
UPPER LEVEL RIDGING BUILDS INTO WESTERN COLORADO. MODELS CONTINUE TO
INDICATE SHOWERS ACROSS THE HIGHER TERRAIN...MOST NUMEROUS ACROSS
THE EASTERN MTS TUESDAY AFTERNOON WITH DEVELOPING LOW LEVEL UPSLOPE
FLOW. MORE ISOLATED HIGH BASED STORMS REMAIN POSSIBLE WEDNESDAY
AFTERNOON.
THURSDAY-FRIDAY...UPPER RIDGE AMPLIFIES INTO THE HIGH PLAINS AS A
BROAD UPPER TROUGH CARVES OUT ACROSS THE PAC NORTHWEST. WARMING
ALOFT WILL ALLOW TEMPS TO WARM BACK TO AT AND SLIGHTLY ABOVE
SEASONAL AVERAGES INTO THE UPCOMING WEEKEND. ISOLATED HIGH BASED
STORMS REMAIN POSSIBLE OVER THE HIGHER TERRAIN WITH INCREASING
SOUTHERLY FLOW LEADING TO THE POTENTIAL FOR LATE AFTERNOON AND
EARLY EVENING THUNDERSTORMS ACROSS THE EASTERN PLAINS...AS LOW
LEVEL MOISTURE STREAMS BACK INTO EASTERN COLORADO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 418 AM MDT SAT MAY 18 2013
VFR CONDITIONS ARE EXPECTED TO NEXT 24 HOURS AT KCOS...KPUB AND
KALS TAF SITES. SOME GUSTY SOUTHWEST WINDS ARE EXPECTED THIS
AFTERNOON AT THE TAF SITES...THEN BECOMING WESTERLY BY EVENING.
THIS AFTERNOON THERE COULD BE SOME SHOWERS/TSTMS IN THE VCNTY OF
KALS AND POSSIBLY NR KCOS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 8 PM MDT THIS EVENING FOR
COZ224-227-233-237.
&&
$$
SHORT TERM...28
LONG TERM...MW
AVIATION...28
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
653 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A FRONTAL BOUNDARY EXTENDED FROM THE NORTH CENTRAL STATES, ACROSS
THE OHIO RIVER VALLEY TO THE WATERS OFF NORTH CAROLINA EARLY THIS
MORNING. THE BOUNDARY IS EXPECTED TO WEAKEN AND DISSIPATE AS IT
MEANDERS OVER THE SAME GENERAL AREA THROUGH MONDAY. MEANWHILE,
HIGH PRESSURE SHOULD REMAIN TO OUR NORTHEAST AND EAST. ANOTHER
FRONTAL BOUNDARY FROM THE NORTH IS FORECAST TO DROP INTO OUR
REGION ON TUESDAY NIGHT AND WEDNESDAY. THE FRONT MAY BEGIN TO LIFT
BACK TO THE NORTH LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A 09Z SURFACE ANALYSIS PLACED HIGH PRESSURE ACROSS THE NORTHEAST
INTO SOUTHEASTERN CANADA. A STATIONARY FRONT WAS DRAPED FROM THE
NORTHERN PLAINS TO THE UPPER OHIO VALLEY, THEN DOWN ACROSS
VIRGINIA AND EASTERN NORTH CAROLINA. AN UPPER AIR ANALYSIS SHOWED
A TROUGH IN THE WEST AND A RIDGE FROM THE MIDWEST INTO THE GREAT
LAKES. A TROUGH WAS IN NORTHERN NEW ENGLAND. THERE WERE SEVERAL
AREAS OF FOCUSED 850 MB WAA FROM THE MIDWEST DOWN THROUGH THE
PLAINS.
SOME LIGHT RETURNS SHOWING UP ON RADAR FROM OUR CENTRAL ZONES ON
SOUTHWARD. THIS APPEARS TO BE IN RESPONSE TO THE GRADUAL LOW-LEVEL
WAA AND AN UPPER-LEVEL JET ZIPPING BY. THE LATEST HRRR HAS THIS IDEA,
ALTHOUGH ITS AREAL COVERAGE IS OVERDONE SO FAR. ANY SHOWER SHOULD
BE LIGHT AND BRIEF THIS MORNING, THEREFORE JUST ADDED SOME
SPRINKLES FOR AWHILE FARTHER NORTH BEFORE SWITCHING TO A SHOWER
MENTION. THE HOURLY GRIDS WERE TWEAKED BASED ON THE 10Z
OBSERVATIONS, WHICH INCLUDED AN UPWARD ADJUSTMENT FOR MANY LOCALES.
OTHERWISE, OUR SENSIBLE WEATHER IS ANTICIPATED TO BE IN A
TRANSITIONING STATE TODAY. THIS IS COURTESY OF A MID LEVEL LOW
THAT IS GENERALLY WEAKENING AS IT SLIDES EASTWARD FROM THE OHIO
VALLEY. GIVEN THE NORTHWESTERLY FLOW ALOFT HOWEVER, THIS FEATURE
IS ANTICIPATED TO BE GENERALLY DIRECTED TOWARD OUR SOUTH TODAY.
THIS FEATURE IS EMBEDDED IN A BUILDING MID LEVEL RIDGE FROM THE
LOWER MISSISSIPPI VALLEY AND INTO THE GREAT LAKES. THE MAIN
FORECAST CHALLENGE FOR TODAY /AND EVEN THROUGH TONIGHT/ IS THE
TIMING AND AREAL COVERAGE OF SHOWERS ARRIVING FROM THE SOUTHWEST.
HIGH PRESSURE OVER SOUTHEASTERN CANADA IS FORECAST TO BUILD SOUTH-
SOUTHEAST, AND THIS MAY HELP HOLD THE NORTHEASTWARD ADVANCEMENT OF
THE SHOWERS.
THE MID LEVEL LOW IS PRODUCING SOME LOW-LEVEL WAA ALONG WITH SOME
THETA-E ADVECTION. THIS IS THE MOST PRONOUNCED ACROSS THE DELMARVA
AND THEN EVENTUALLY ACROSS SOUTHERN NEW JERSEY. THIS WILL RESULT
IN ISENTROPIC LIFT, HOWEVER THIS IS GENERALLY ON THE WEAKER SIDE.
THE OVERALL LIFT FARTHER NORTH IS EVEN WEAKER, HOWEVER THERE IS A
THERMAL GRADIENT FORECAST TO BE IN PLACE ALONG WITH A THETA-E
GRADIENT. AT THE SURFACE, A SOUTHEASTERLY FLOW IS EXPECTED WHICH
WILL GRADUALLY HELP TO INCREASE THE LOW-LEVEL MOISTURE. ALL OF
THIS IS FORECAST TO BE ON THE WEAKER SIDE, THEREFORE MOSTLY AN
INCREASE IN CLOUDS IS ANTICIPATED THROUGH THE DAY WITH SOME
SHOWERS MAINLY ACROSS THE DELMARVA. SOME ONGOING CONVECTION ACROSS
VIRGINIA EARLY THIS MORNING APPEARS TO BE FOCUSED NEAR THE STALLED
FRONT AND WITHIN AN AREA OF DEEPER MOISTURE. THIS ACTIVITY APPEARS
TO STAY JUST SOUTH OF DELAWARE EARLY THIS MORNING. THE FORECAST
SOUNDINGS ALSO INDICATE THE MOISTENING IS GRADUAL, THEREFORE WE
ARE NOT ANTICIPATING LOW CLOUDS DEVELOPING DESPITE THE
SOUTHEASTERLY FLOW. THE AIR MASS ACROSS OUR CWA TODAY LOOKS STABLE
ENOUGH, THEREFORE WE CONTINUED TO NOT INCLUDE A THUNDER MENTION.
AS FOR HIGH TEMPERATURES, THE AMOUNT OF CLOUD COVER ALONG WITH A
SOUTHEASTERLY FLOW WILL HELP TO KEEP THEM COOLER THAN YESTERDAY
FOR MANY AREAS. THIS WILL ALSO RESULT IN COOL CONDITIONS CLOSER TO
THE COAST. WE USED AN EVEN BLEND OF THE GFS/NAM MOS WITH SOME
MAINLY MINOR ADJUSTMENTS. THE WARMEST TEMPERATURES ARE MAINLY
ACROSS THE NORTHERN ZONES WHERE MORE FILTERED SUNSHINE MAY HOLD
THE LONGEST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE WEAK MID LEVEL LOW WILL CONTINUE TO TRACK EASTWARD INTO THE
DELMARVA. MEANWHILE, THE CENTER OF HIGH PRESSURE IS FORECAST TO
SLIDE SOUTHWARD OFF THE NEW ENGLAND COAST. THIS WILL RESULT IN A
CONTINUATION OF A SOUTHEASTERLY FLOW AT THE SURFACE, WHICH VEERS
TO MORE SOUTHERLY AT 850 MB. AS THIS OCCURS, THE LOW-LEVEL WAA IS
MAINTAINED WITH EVEN SOME INCREASE IN THE WINDS ACROSS THE
SOUTHERN ZONES TOWARD MORNING. THIS ALONG WITH CONTINUED THETA-E
ADVECTION IS EXPECTED TO RESULT IN ENOUGH ISENTROPIC LIFT TO
PRODUCE AN EXPANDING AREA OF SHOWERS FROM NORTH TO SOUTH. THE
AREAL COVERAGE OF THE SHOWERS IS SOMEWHAT IN QUESTION THOUGH,
THEREFORE WE OPTED TO HOLD THE POPS UNDER LIKELY. IT MAY TAKE ALL
NIGHT FOR ANY SHOWERS TO REACH THE FAR NORTHERN ZONES AS SOME
DRIER AIR MAY HOLD ON WITH THE MAIN THETA-E ADVECTION AND WAA
FOCUSED FARTHER SOUTH. THEREFORE, WE SLOWED THE INCREASE IN THE
POPS SOME FROM SOUTH TO NORTH. THE AIR MASS ACROSS OUR CWA LOOKS
STABLE ENOUGH, THEREFORE WE CONTINUED TO NOT INCLUDE A THUNDER
MENTION.
THE COMBINATION OF LOW-LEVEL WAA AND MOISTURE ADVECTION WILL
RESULT IN A RATHER CLOUDY NIGHT. THE CLOUDS ARE EXPECTED TO LOWER
THROUGH THE NIGHT AS THE BOUNDARY LAYER MOISTENS UP. THE FORECAST
SOUNDINGS GENERALLY SHOW THIS PROCESS NOT BEING RUSHED, THEREFORE
WE DID NOT INCLUDE DRIZZLE. THIS IS ALSO SUPPORTED BY JUST ENOUGH
DRY AIR IN THE BOUNDARY LAYER REMAINING A BIT LONGER. AN ONSHORE
FLOW CAN BE TRICKY SOMETIMES, THEREFORE WE WILL SEE HOW QUICK THE
MOISTURE MOVES IN AND DEEPENS. THIS SHOULD ALSO LIMIT ANY FOG
OVERNIGHT, ESPECIALLY AS THE DEW POINTS ARE NOT FORECAST TO
RAPIDLY INCREASE.
AS FOR LOW TEMPERATURES, WE WENT WITH AN EVEN GFS/NAM MOS BLEND.
THE TEMPERATURES ONCE THEY FALL BACK DURING THE EVENING MAY TEND
TO HOLD NEARLY STEADY AS CLOUDS LOWER.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE MID LEVEL PATTERN IS EXPECTED TO FEATURE THE POLAR VORTEX
WELL TO OUR NORTHEAST WITH A TROUGH SETTLING OVER THE WESTERN HALF
OF THE COUNTRY ON SUNDAY. THERE SHOULD BE A RIDGE OVER THE EAST
WITH ITS AXIS EXTENDING FROM THE WATERS OFF THE SOUTHEAST COAST TO
THE GREAT LAKES. THE POLAR VORTEX WILL REMAIN THE DOMINANT FEATURE
OVER EASTERN CANADA DURING THE NEW WEEK. MEANWHILE, THE TROUGH TO
OUR WEST WILL PROGRESS EASTWARD, GRADUALLY SQUEEZING THE RIDGE AND
PUSHING IT OUT OVER THE ATLANTIC. AS THE TROUGH BEGINS TO MOVE
TOWARD THE EASTERN STATES LATE IN THE WEEK, IT SHOULD BEGIN TO
INTERACT WITH THE POLAR VORTEX. ALL IN ALL, WE ARE ANTICIPATING A
RATHER UNSETTLED PERIOD.
SURFACE HIGH PRESSURE TO OUR NORTHEAST AND EAST WILL RESULT IN A
PREVAILING SURFACE FLOW FROM THE EAST TO SOUTH QUADRANT FOR SUNDAY
AND SUNDAY NIGHT. THE MOIST FLOW OFF THE OCEAN WILL LIKELY RESULT
IN A PERIOD OF LOW CLOUDS ALONG WITH A CHANCE FOR RAIN SHOWERS.
THE SURFACE FLOW IS FORECAST TO VEER TO THE SOUTH AND SOUTHWEST
FOR MONDAY AND MONDAY NIGHT CAUSING THE CLOUDS TO LIFT AND
TEMPERATURES TO WARM, RESULTING IN THE DEVELOPMENT OF UNSTABLE
CONDITIONS, ESPECIALLY AWAY FROM THE OCEAN. A FAIR AMOUNT OF LOW
LEVEL MOISTURE WILL REMAIN IN OUR REGION. AS A RESULT, WE WILL
CONTINUE TO MENTION A CHANCE OF SHOWERS AND WE WILL ALSO INCLUDE A
CHANCE OF THUNDERSTORMS FOR THE AFTERNOON AND INTO THE NIGHTTIME
HOURS ROUGHLY ALONG THE INTERSTATE 95 CORRIDOR AND AT LOCATIONS TO
THE WEST.
THE SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON TUESDAY AND
TEMPERATURES ARE EXPECTED TO RISE INTO THE LOWER AND MIDDLE 80S IN
MUCH OF OUR FORECAST AREA. LINGERING LOW LEVEL MOISTURE WILL HELP
ENHANCE THE INSTABILITY AND WE ARE ANTICIPATING SCATTERED SHOWERS
AND THUNDERSTORMS, ESPECIALLY IN THE AFTERNOON AND EVENING.
A FRONTAL BOUNDARY IS FORECAST TO DROP INTO OUR REGION FROM THE
NORTH FOR TUESDAY NIGHT AND WEDNESDAY. THERE IS A FAIR AMOUNT OF
UNCERTAINTY AS TO WHETHER THE FRONT WILL REMAIN OVER OR NEAR OUR
REGION THROUGH THE BALANCE OF THE WEEK OR IF IT WILL TRY TO LIFT
BACK TO THE NORTH. REGARDLESS, UNSETTLED CONDITIONS WILL LIKELY
CONTINUE.
WHILE THERE WILL BE A CHANCE OF PRECIPITATION IN THE FORECAST FOR
EACH DAY FROM SUNDAY THROUGH FRIDAY, THE WEEK SHOULD NOT BE A
TOTAL WASHOUT. ACTUALLY, MOST OF THE TIME PRECIPITATION WILL NOT
BE FALLING. OVERALL, TEMPERATURES FOR THE WEEK SHOULD AVERAGE
ABOVE NORMAL FOR THIS TIME OF THE YEAR.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR WITH CEILINGS MAINLY 8,000 TO 10,000 FEET LOWERING
SOME THROUGH THE AFTERNOON. LIGHT AND VARIABLE WINDS, BECOMING
SOUTHEASTERLY NEAR 10 KNOTS. AN ISOLATED LIGHT SHOWER AROUND THIS
MORNING, THEN ADDITIONAL SHOWERS ARE ANTICIPATED TO BE MOSTLY
SOUTH OF KPHL.
TONIGHT...VFR CEILINGS TO START, THEN THESE SHOULD LOWER TO MVFR
BY ABOUT 04Z. THERE IS A CHANCE SOME IFR CEILINGS DEVELOP, HOWEVER
CONFIDENCE IS LOW THEREFORE HELD CEILINGS JUST ABOVE FOR NOW.
SCATTERED SHOWERS DEVELOPING FROM SOUTH TO NORTH, WITH THE
GREATEST CHANCE MAINLY FROM THE KPHL METRO ON SOUTHWARD. ANY
SHOWERS WILL LOWER THE LOCAL VISIBILITY AT TIMES. ANY FOG SHOULD
BE LIMITED AS THE MOISTURE GOES INTO A LOWERING CLOUD DECK.
EAST-SOUTHEAST WINDS 5-8 KNOTS.
OUTLOOK...
SUNDAY AND SUNDAY NIGHT...MAINLY MVFR CEILINGS WITH POSSIBLE IFR
CONDITIONS AT TIMES. A CHANCE OF SHOWERS.
MONDAY THROUGH WEDNESDAY...MAINLY VFR. HOWEVER, MVFR AND IFR
CONDITIONS ARE POSSIBLE ESPECIALLY DURING THE LATE NIGHT AND EARLY
MORNING HOURS EACH DAY. ALSO, THERE WILL BE A CHANCE OF SHOWERS
AND THUNDERSTORMS WHICH COULD LOWER CEILINGS AND REDUCE THE
VISIBILITY.
&&
.MARINE...
HIGH PRESSURE CENTERED TO OUR NORTH WILL SETTLE SOUTHWARD SOME
THROUGH TONIGHT. MEANWHILE, A FRONTAL BOUNDARY REMAINS STALLED TO
OUR SOUTH. AS A RESULT, AN EAST TO SOUTHEAST FLOW WILL BECOME
DOMINANT THROUGH TONIGHT. THE PRESSURE GRADIENT IS FORECAST TO
TIGHTEN UP SOME THIS AFTERNOON AND TONIGHT, HOWEVER THE OVERALL
WIND IS FORECAST TO NOT BE ROBUST BELOW AN INVERSION. WE ARE
ANTICIPATING SOME INCREASE AS WE GO THROUGH TONIGHT ESPECIALLY
ACROSS THE SOUTHERN WATERS AND UP DELAWARE BAY /GUSTS TO 20
KNOTS/, HOWEVER WE CONTINUE TO KEEP THE WINDS BELOW ADVISORY
CRITERIA. THE SEAS WILL GRADUALLY RESPOND TO THE WINDS, HOWEVER
PERHAPS A LITTLE SLOWER THAN WHAT WAVEWATCH GUIDANCE SUGGESTS.
THEREFORE, CONDITIONS ARE FORECAST TO REMAIN BELOW ADVISORY
CRITERIA THROUGH TONIGHT.
OUTLOOK...
HIGH PRESSURE TO OUR NORTHEAST AND EAST WILL CONTINUE TO
INFLUENCE THE COASTAL WATERS OF NEW JERSEY AND DELAWARE INTO
TUESDAY. A FRONTAL BOUNDARY FROM THE NORTH IS FORECAST TO DROP
INTO OUR REGION FOR TUESDAY NIGHT AND WEDNESDAY.
WIND SPEEDS ARE FORECAST TO REMAIN LESS THAN 25 KNOTS FROM SUNDAY
THROUGH WEDNESDAY. WAVE HEIGHTS ON OUR OCEAN WATERS MAY BUILD TO
AROUND 5 FEET ON SUNDAY AND SUNDAY NIGHT AND THEY COULD REMAIN AT
THAT LEVEL THROUGH AT LEAST WEDNESDAY AS A PERSISTENT SOUTHERLY
FLOW DEVELOPS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...IOVINO
NEAR TERM...GORSE
SHORT TERM...GORSE
LONG TERM...IOVINO
AVIATION...GORSE/IOVINO
MARINE...GORSE/IOVINO
AREA FORECAST DISCUSSION
NWS MIAMI FL
905 AM EDT SAT MAY 18 2013
.UPDATE...
MORNING SOUNDING DATA INDICATES A MOISTENING TREND OF THE LOCAL
AIR MASS. THIS IS CONFIRMED BY RADAR THIS MORNING SHOWING
SCATTERED SHOWERS ALONG THE EAST COAST AND ATLANTIC, WITH EARLIER
SHOWERS OVER THE GULF OF MEXICO AS WELL. THIS ALL POINTS TO A
GENERAL INCREASE IN SHOWERS AND THUNDERSTORMS THIS AFTERNOON,
ESPECIALLY INTERIOR AND LAKE OKEECHOBEE AREAS WHERE SOUTHEAST TO
SOUTH LOW-LEVEL FLOW WILL FOCUS CONVERGENCE. MINOR MID-LEVEL SHORTWAVE
MOVING ACROSS SOUTH FLORIDA FROM THE GULF THIS AFTERNOON WILL COOL
THE MID-LEVELS A BIT THIS AFTERNOON, ACTING TO ERODE MID-LEVEL
CAPPING AND HELPING IN THE DEVELOPMENT OF A FEW STRONG STORMS
ACROSS THE INTERIOR/LAKE AREAS. LIGHTNING, GUSTY WINDS AND SMALL
HAIL ARE THE PRIMARY IMPACTS.
SHOWERS/STORMS THIS AFTERNOON WILL LIKELY MOVE LITTLE OR DRIFT
EAST, WHICH SHOULD RESULT IN METRO/COASTAL AREAS ALONG BOTH COASTS
REMAINING MOSTLY DRY THIS AFTERNOON. IN ALL, NO CHANGES OF NOTE TO
THE PREVIOUS FORECAST PACKAGE.
MOLLEDA
&&
.PREV DISCUSSION... /ISSUED 740 AM EDT SAT MAY 18 2013/
AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS AND POSSIBLY A THUNDERSTORM OR
TWO WILL CONTINUE ACROSS THE COASTAL ATLANTIC WATERS THROUGH THE
MORNING HOURS. STILL EXPECT A FEW OF THESE SHOWERS TO PUSH INLAND
THROUGH THE LATE MORNING HOURS. THEREFORE...KEPT VCSH MENTION AT ALL
EAST COAST SITES. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
PREV DISCUSSION... /ISSUED 300 AM EDT SAT MAY 18 2013/
SHORT TERM (TODAY-MONDAY)...
ANOTHER WARM AND PLEASANT WEEKEND IS ANTICIPATED ACROSS SOUTH
FLORIDA WITH TEMPERATURES REMAINING AROUND TO SLIGHTLY ABOVE NORMAL
EACH DAY. THE LATEST NUMERICAL GUIDANCE REMAINS PERSISTENT AND IN
GOOD AGREEMENT DEPICTING AN UPPER RIDGE BUILDING EASTWARD OVER THE
MS VALLEY TRAILING A SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHWEST
FLOW ALOFT. AS THIS SHORTWAVE ADVANCES E-SEWD OVER THE
STATE...UPPER HEIGHTS WILL SLIGHTLY FALL OVER THE STATE BY THE END
OF THE DAY. MODEL SOUNDINGS ACROSS THE NORTHERN AND INTERIOR
LOCATIONS OF THE LOCAL AREA REFLECT THIS AND INDICATE SOME MID-
LEVEL COOLING BY 00Z (H5 TEMPS AROUND -11C) WITH MID-LEVEL LAPSE
RATES STEEPENING (-6 TO -7 C/KM). THIS COMBINED WITH LIGHT
SOUTHEAST LOW-LEVEL FLOW...A SUFFICIENT AMOUNT OF LOW-LEVEL
MOISTURE AND DAYTIME HEATING WILL SUPPORT A FEW STORMS LATER TODAY
THROUGH THE LATE AFTERNOON/EARLY EVENING TIME FRAME. THE BEST
CHANCE FOR THIS ACTIVITY WILL BE ACROSS THE INTERIOR AND NORTHERN
LOCATIONS. THE FSU GRIDDED LIGHTNING PROBABILITY DATABASE AND THE
LATEST GRIDDED MOS THUNDERSTORM PROBABILITIES ARE GENERALLY
OUTPUTTING 20-40 PERCENT CHANCES OVER THESE INTERIOR LOCATIONS
THROUGH THIS TIME. THE MAIN LIMITING FACTORS FOR WIDESPREAD DEEP
MOIST CONVECTION WILL BE A PERSISTENT MID-LEVEL CAP BETWEEN 650 MB
AND 700 MB ALONG WITH PLENTY OF MID-LEVEL DRY AIR EN-TRAINING INTO
ANY DEVELOPING CELLS. ANY STORM THAT DOES DEVELOP COULD BECOME
STRONG WITH THE MAIN IMPACTS BEING SMALL HAIL AND DAMAGING
STRAIGHT-LINE WINDS (40-55 MPH). THE LATEST HI-RES MODEL
REFLECTIVITIES BETWEEN THE WRF AND NAM GENERALLY LINE UP WELL AND
DEPICT SOME ACTIVITY INITIATING INLAND AND TOWARD THE NORTH AROUND
LAKE OKEECHOBEE THROUGH THE LATE AFTERNOON AND EARLY EVENING
PERIODS. SIMILAR CONDITIONS WILL PERSIST WITH THE EASTERLY LOW-
LEVEL FAVORING INTERIOR AFTERNOON ACTIVITY AGAIN ON SUNDAY AND
MONDAY. OVERNIGHT AND THROUGH THE EARLY MORNING HOURS EACH
DAY...SHOWERS AND A FEW STORMS ACROSS THE ATLANTIC WATERS AND THE
EAST COAST LOCATIONS WILL REMAIN POSSIBLE DUE TO THE CONFLUENT
BOUNDARIES SETTING UP DOWNSTREAM OF THE BAHAMAS AND RADIATIONAL
CLOUD-TOP COOLING.
LONG TERM (MONDAY NIGHT-FRIDAY)...
THE GFS/ENSEMBLE MEAN AND ECMWF GENERALLY REMAIN IN GOOD AGREEMENT
THROUGH THE EXTENDED PERIOD AND INDICATE A PERSISTENT UPPER TROUGH
CONTINUING TO INFLUENCE THE LOCAL AREA. ADDITIONALLY...A SURGE OF
DEEP LAYER MOISTURE LATER IN THE WEEK ASSOCIATED WITH A WEAK SURFACE
TROUGH EMBEDDED IN THE EASTERLY FLOW COMBINED WITH THE UPPER TROUGH
COULD LEAD TO MORE WIDESPREAD RAINFALL ACTIVITY EACH DAY WEDNESDAY
THROUGH FRIDAY. HOWEVER...WE WILL CONTINUE TO MONITOR LATER MODEL
TRENDS FOR CONSISTENCY OVER THE WEEKEND BEFORE INCREASING THE
RAINFALL CHANCES. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL EACH DAY.
AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS WILL CONTINUE ACROSS THE COASTAL
ATLANTIC WATERS THROUGH THE EARLY MORNING HOURS. LATEST HRRR AND
LOCAL MODELS INCREASE COVERAGE OF SHOWERS THROUGH THE MORNING AND
PUSH THEM INLAND ACROSS THE EAST COAST METRO AREAS UNDER WEAK
EASTERLY FLOW. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
MARINE...
LIGHT TO MODERATE EAST AND SOUTHEAST WINDS WILL CONTINUE THROUGH
MUCH OF THE FORECAST PERIOD AS HIGH PRESSURE REMAINS IN CONTROL
NORTHEAST OF THE MARINE AREA. ISOLATED OVERNIGHT AND EARLY MORNING
SHOWERS WILL REMAIN POSSIBLE EACH DAY ACROSS THE ATLANTIC WATERS.
FIRE WEATHER...
SOUTHEAST LOW-LEVEL WINDS ALONG WITH PLENTY OF LOW-LEVEL MOISTURE
WILL PERSIST THROUGH THE WEEKEND. MOST OF THE SHOWERS AND STORMS
THAT DEVELOP WILL BE FOCUSED ALONG THE EAST COAST THROUGH THE EARLY
MORNING HOURS AND ACROSS THE INTERIOR LOCATIONS THROUGH THE
AFTERNOON/EVENING PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 74 85 74 / 20 20 20 20
FORT LAUDERDALE 85 76 86 76 / 20 20 20 20
MIAMI 87 75 87 75 / 20 20 20 20
NAPLES 89 71 89 71 / 20 20 30 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE...59/MOLLEDA
AVIATION/RADAR/FIRE...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
740 AM EDT SAT MAY 18 2013
.AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS AND POSSIBLY A THUNDERSTORM OR
TWO WILL CONTINUE ACROSS THE COASTAL ATLANTIC WATERS THROUGH THE
MORNING HOURS. STILL EXPECT A FEW OF THESE SHOWERS TO PUSH INLAND
THROUGH THE LATE MORNING HOURS. THEREFORE...KEPT VCSH MENTION AT ALL
EAST COAST SITES. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
&&
.PREV DISCUSSION... /ISSUED 300 AM EDT SAT MAY 18 2013/
SHORT TERM (TODAY-MONDAY)...
ANOTHER WARM AND PLEASANT WEEKEND IS ANTICIPATED ACROSS SOUTH
FLORIDA WITH TEMPERATURES REMAINING AROUND TO SLIGHTLY ABOVE NORMAL
EACH DAY. THE LATEST NUMERICAL GUIDANCE REMAINS PERSISTENT AND IN
GOOD AGREEMENT DEPICTING AN UPPER RIDGE BUILDING EASTWARD OVER THE
MS VALLEY TRAILING A SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHWEST
FLOW ALOFT. AS THIS SHORTWAVE ADVANCES E-SEWD OVER THE
STATE...UPPER HEIGHTS WILL SLIGHTLY FALL OVER THE STATE BY THE END
OF THE DAY. MODEL SOUNDINGS ACROSS THE NORTHERN AND INTERIOR
LOCATIONS OF THE LOCAL AREA REFLECT THIS AND INDICATE SOME MID-
LEVEL COOLING BY 00Z (H5 TEMPS AROUND -11C) WITH MID-LEVEL LAPSE
RATES STEEPENING (-6 TO -7 C/KM). THIS COMBINED WITH LIGHT
SOUTHEAST LOW-LEVEL FLOW...A SUFFICIENT AMOUNT OF LOW-LEVEL
MOISTURE AND DAYTIME HEATING WILL SUPPORT A FEW STORMS LATER TODAY
THROUGH THE LATE AFTERNOON/EARLY EVENING TIME FRAME. THE BEST
CHANCE FOR THIS ACTIVITY WILL BE ACROSS THE INTERIOR AND NORTHERN
LOCATIONS. THE FSU GRIDDED LIGHTNING PROBABILITY DATABASE AND THE
LATEST GRIDDED MOS THUNDERSTORM PROBABILITIES ARE GENERALLY
OUTPUTTING 20-40 PERCENT CHANCES OVER THESE INTERIOR LOCATIONS
THROUGH THIS TIME. THE MAIN LIMITING FACTORS FOR WIDESPREAD DEEP
MOIST CONVECTION WILL BE A PERSISTENT MID-LEVEL CAP BETWEEN 650 MB
AND 700 MB ALONG WITH PLENTY OF MID-LEVEL DRY AIR ENTRAINING INTO
ANY DEVELOPING CELLS. ANY STORM THAT DOES DEVELOP COULD BECOME
STRONG WITH THE MAIN IMPACTS BEING SMALL HAIL AND DAMAGING
STRAIGHT-LINE WINDS (40-55 MPH). THE LATEST HI-RES MODEL
REFLECTIVITIES BETWEEN THE WRF AND NAM GENERALLY LINE UP WELL AND
DEPICT SOME ACTIVITY INITIATING INLAND AND TOWARD THE NORTH AROUND
LAKE OKEECHOBEE THROUGH THE LATE AFTERNOON AND EARLY EVENING
PERIODS. SIMILAR CONDITIONS WILL PERSIST WITH THE EASTERLY LOW-
LEVEL FAVORING INTERIOR AFTERNOON ACTIVITY AGAIN ON SUNDAY AND
MONDAY. OVERNIGHT AND THROUGH THE EARLY MORNING HOURS EACH
DAY...SHOWERS AND A FEW STORMS ACROSS THE ATLANTIC WATERS AND THE
EAST COAST LOCATIONS WILL REMAIN POSSIBLE DUE TO THE CONFLUENT
BOUNDARIES SETTING UP DOWNSTREAM OF THE BAHAMAS AND RADIATIONAL
CLOUD-TOP COOLING.
LONG TERM (MONDAY NIGHT-FRIDAY)...
THE GFS/ENSEMBLE MEAN AND ECMWF GENERALLY REMAIN IN GOOD AGREEMENT
THROUGH THE EXTENDED PERIOD AND INDICATE A PERSISTENT UPPER TROUGH
CONTINUING TO INFLUENCE THE LOCAL AREA. ADDITIONALLY...A SURGE OF
DEEP LAYER MOISTURE LATER IN THE WEEK ASSOCIATED WITH A WEAK SURFACE
TROUGH EMBEDDED IN THE EASTERLY FLOW COMBINED WITH THE UPPER TROUGH
COULD LEAD TO MORE WIDESPREAD RAINFALL ACTIVITY EACH DAY WEDNESDAY
THROUGH FRIDAY. HOWEVER...WE WILL CONTINUE TO MONITOR LATER MODEL
TRENDS FOR CONSISTENCY OVER THE WEEKEND BEFORE INCREASING THE
RAINFALL CHANCES. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL EACH DAY.
AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS WILL CONTINUE ACROSS THE COASTAL
ATLANTIC WATERS THROUGH THE EARLY MORNING HOURS. LATEST HRRR AND
LOCAL MODELS INCREASE COVERAGE OF SHOWERS THROUGH THE MORNING AND
PUSH THEM INLAND ACROSS THE EAST COAST METRO AREAS UNDER WEAK
EASTERLY FLOW. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
MARINE...
LIGHT TO MODERATE EAST AND SOUTHEAST WINDS WILL CONTINUE THROUGH
MUCH OF THE FORECAST PERIOD AS HIGH PRESSURE REMAINS IN CONTROL
NORTHEAST OF THE MARINE AREA. ISOLATED OVERNIGHT AND EARLY MORNING
SHOWERS WILL REMAIN POSSIBLE EACH DAY ACROSS THE ATLANTIC WATERS.
FIRE WEATHER...
SOUTHEAST LOW-LEVEL WINDS ALONG WITH PLENTY OF LOW-LEVEL MOISTURE
WILL PERSIST THROUGH THE WEEKEND. MOST OF THE SHOWERS AND STORMS
THAT DEVELOP WILL BE FOCUSED ALONG THE EAST COAST THROUGH THE EARLY
MORNING HOURS AND ACROSS THE INTERIOR LOCATIONS THROUGH THE
AFTERNOON/EVENING PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 74 85 74 / 20 20 20 20
FORT LAUDERDALE 85 76 86 76 / 20 20 20 20
MIAMI 87 75 87 75 / 20 20 20 20
NAPLES 89 71 89 71 / 20 20 30 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...59/RM
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
747 AM EDT SAT MAY 18 2013
.PREV DISCUSSION... /ISSUED 438 AM EDT SAT MAY 18 2013/
SHORT TERM /TODAY THROUGH SUNDAY/...
COMPLEX AND DIFFICULT FORECAST THE NEXT 24 TO 36 HOURS. SLOW MOVING
AND WEAK UPPER LEVEL LOW NOTED IN WATER VAPOR OVER CENTRAL TN
RESPONSIBLE FOR SHOWERS AND A FEW STORMS MOVING INTO WESTERN GA NOW
THROUGH SAT AM. MODELS CONTINUE TO KEEP THE REGION IN A GENERAL
NORTHWEST FLOW PATTERN THROUGH SUNDAY WITH WEAK DISTURBANCES MOVING
SOUTHEAST ON THE SOUTHWEST SIDE OF THE WEAK UPPER LOW. ALL OF THE
MODELS AGREE ON CHANCE TO LIKELY POPS FOR A PORTION OF THE AREA BUT
DISAGREE ON EXACT LOCATION AND TIMING...MOST LIKELY DUE TO
DIFFICULTIES RESOLVING THESE FEATURES. FOR TODAY...BIG QUESTION
WITH THIS ONGOING ACTIVITY IS HOW MUCH CLOUD DEBRIS WILL REMAIN AND
HINDER OR DELAY ANY DAYTIME HEATING ACROSS GA AND THE ONSET OF
THUNDERSTORM DEVELOPMENT. HRRR AND HIGH RES WRF CONTINUE TO SHOW
SHOWERS THROUGH MORNING WITH MORE SCATTERED CONVECTION DEVELOPING
THIS AFTERNOON. AS A RESULT...HAVE OPTED TO MAINTAIN SOME
CONSISTENCY WITH THE PREVIOUS FORECAST WHICH SHOWS HIGHEST POPS
ACROSS NORTHERN GA THROUGH SAT AND LESSER POPS ACROSS THE SOUTHERN TIER.
WILL HAVE TO WATCH THE SOUTHERN TIER OF COUNTIES AS DIFFERENTIAL
HEATING MAY HAVE A BIGGER THAN CURRENT MODELS FORECASTING GIVEN THE
LOCATION OF THE CURRENT ACTIVITY.
WILL HAVE TO WATCH AREA SAT NIGHT INTO SUNDAY AS SEVERAL MODELS ARE
HINTING AT SOME TYPE OF MCS DEVELOPMENT IN NORTHERN AL AND TN. GIVEN
THE NORTHWEST FLOW AND THESE DISTURBANCES...CANT RULE IT OUT. GFS
INSTABILITY FORECAST FOR SUNDAY IS IMPRESSIVE WITH 500 TO 700 MB
LAPSE RATES OVER 8 DEG C/KM FOR NORTHWEST GA. ALONG WITH CAPE
VALUES 2000 TO AS MUCH AS 4000 J/KG ... THERE WILL BE SOME SEVERE
POTENTIAL...HOWEVER SHEAR VALUES ARE LESS THAN MARGINAL SO
CONFIDENCE ON A MORE WIDESPREAD SEVERE EVENT IS LESS. MAIN IMPACTS
WILL BE DAMAGING WINDS AND HAIL. TIMING OF STORMS ON SUNDAY IS A
CRAP SHOOT AT THIS POINT AND MODEL TIMING IS ALL OVER THE PLACE
GIVEN THE POTENTIAL MCS DEVELOPMENT EARLY ON SUN. NEEDLESS TO
SAY...WILL NEED TO WATCH THE FORECAST CLOSELY THROUGH THE WEEKEND AS
IT COULD CHANGE SIGNIFICANTLY FOR BETTER OR WORSE.
HIGH PW VALUES AND THE SLOW MOVING NATURE OF THESE DISTURBANCES HAVE
THE POTENTIAL TO PRODUCE SOME ISOLATED FLASH FLOODING...PARTICULARLY
ACROSS NORTH GA BOTH SAT AND SUN. WILL NEED TO ALSO MONITOR THIS AS
WELL AS THE SEVERE THREAT.
30
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HAVE ADJUSTED POPS UPWARD FOR SUNDAY NIGHT ACROSS THE CWFA. MODELS
ARE SHOWING SIGNS OF AN MCS DEVELOPING IN THE NW FLOW AND AFFECTING
THE CWFA. STRONG SURFACE INSTABILITY AND VERY STEEP LAPSE RATES WILL
HELP SUSTAIN CONVECTION AND CONTINUE THE POSSIBILITY OF SEVERE
STORMS AT LEAST THROUGH MIDNIGHT.
FOR MONDAY...A 500MB TROUGH/SHEAR AXIS SETS UP RIGHT ALONG THE SE
COAST. THIS FEATURE SHOULD SERVE TO FOCUS ANY CONVECTIVE ACTIVITY
FOR MONDAY AND MONDAY EVENING. DO THINK SHRA/TSRA WILL BE MORE
DIURNAL IN NATURE. KEPT THE TREND OF HIGHEST POPS IN THE EAST...WITH
ONLY ISOLATED ACTIVITY TO THE WEST.
WEAK SHEAR AXIS/500MB TROUGH MOVES OFF THE COAST ON TUESDAY WITH
RIDGING BUILDING ALOFT ACROSS THE CWFA. ANY CONVECTION SHOULD BE
ISOLATED IN NATURE...SURFACE INSTABILITY WILL BE PRESENT BUT NO
DISCERNIBLE SURFACE MECHANISM TO FOCUS PRECIP IS NOTED. PRECIP
SHOULD BE DIURNAL.
UNCERTAINTY BEGINS TO CREEP INTO THE FORECAST BY WEDNESDAY. EARLIER
MODEL RUNS PROGGED A COLD FRONT TO MOVE THROUGH THE CWFA DURING THE
LATTER HALF OF THE WEEK. THE ECMWF NOW KEEPS THE FRONT TO THE
NORTH...WHILE THE GFS DOES MOVE THE BOUNDARY THROUGH SLOWLY FRIDAY
THROUGH SATURDAY. HAVE OPTED TO GO PERSISTENCE FOR THIS PERIOD DUE
TO LOW CONFIDENCE.
NLISTEMAA
AVIATION...
06Z UPDATE...
SHOWERS AND A FEW EMBEDDED TSTORMS WORKING EAST OUT OF AL INTO GA
TONIGHT. TIME OF ARRIVAL ON MAIN CELLS FOR ATLANTA AREA SITES
BETWEEN 07Z AND 08Z BUT AM NOT CONFIDENT THEY WILL HOLD TOGETHER
AS AIRMASS IS A LITTLE MORE STABLE ACROSS GA. THIS IS EVIDENT IN THE
LARGER CELL WEST OF CSG WHICH HAS BEEN WEAKENING AS IT MOVES EAST.
DID INCLUDE TSRA IN A TEMPO GROUP AT ATL OVERNIGHT FOR SOME OF THE
STRONGER CELLS. HRRR AND HIGH RES MODELS CONTINUE TO SHOW THE EAST WEST
BANDING OF STORMS THROUGH MID MORNING BUT PRIMARILY OVER AL AND
EXTREME WESTERN GA. WILL NEED TO MONITOR THIS FOR ANY SLIGHT
EASTWARD EXTENSION AND THE NEED TO AMD WITH THUNDER.
OTHERWISE...BELIEVE CLOUD DEBRIS WILL HAMPER EARLY TS DEVELOPMENT
ON SAT BUT STILL THINK TSTORMS WILL DEVELOP IN THE AFTERNOON
PARTICULARLY ACROSS NORTH GA. MVFR CIGS AND VSBYS ARE POSSIBLE
OVERNIGHT PARTICULARLY IN SHOWERS MAINLY BETWEEN 08Z AND 12Z AND
WINDS ARE EXPECTED TO REMAIN GENERALLY LIGHT OUT OF THE SOUTHWEST
BUT INCREASING TO AROUND 10KTS AFTER 16Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS
30
&&
.AVIATION...
12Z UPDATE...
MADE SOME CHANGES IN THE TAF BASED ON THE SHORT TERM TRENDS TO
OPEN UP A MORE RAIN FREE WINDOW FROM AROUND 15Z THROUGH EARLY
AFTERNOON. EXPECT THE RAIN COOLED AIR TO STABILIZE THE ATMSPHERE
FOR A FEW HOURS BEFORE STORMS BEGIN TO REDEVELOP THIS AFTERNOON.
HRRR AND WRF SUPPORT NEW DEVELOPMENT AROUND 20Z ACROSS NORTH GA
HOWEVER COVERAGE IS IN QUESTION AT THIS POINT. WINDS AND CIGS
CONSISTENT WITH PREVIOUS DISCUSSION.
//ATL CONFIDENCE...12Z UPDATE...
CONFIDENCE MEDIUM ON CIGS...VSBY.
CONFIDENCE LOW ON PRECIP TIMING.
30
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 80 63 79 65 / 60 60 60 60
ATLANTA 78 65 79 66 / 70 70 60 60
BLAIRSVILLE 73 60 76 60 / 70 70 70 70
CARTERSVILLE 78 63 79 65 / 70 70 60 50
COLUMBUS 83 67 85 67 / 90 50 40 50
GAINESVILLE 76 63 76 63 / 70 70 70 60
MACON 85 64 84 66 / 50 50 60 60
ROME 79 63 81 65 / 70 70 60 40
PEACHTREE CITY 79 64 79 65 / 60 60 60 60
VIDALIA 88 69 87 68 / 40 40 60 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
749 AM EDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT SAT MAY 18 2013
IN THE LARGE SCALE...TROUGH OVER THE ROCKIES WILL SLIDE ONTO THE
HIGH PLAINS BY SUNDAY MORNING ALLOWING RIDGING TO SLIGHTLY BUILD
OVER THE WESTERN GREAT LAKES. ALTHOUGH SFC-H85 TROUGHING OVER THE
DAKOTAS DOES NOT MOVE MUCH TO THE EAST...IT IS ENOUGH TO INCREASE
LOW-LEVEL SOUTHERLY FLOW ACROSS THE UPPER GREAT LAKES. PATTERN IS
SERVING TO INCREASE MOISTURE /PWATS 1.15 OF 1.31 INCHES AT GRB AND
MPX OR AROUND 200 PCT OF NORMAL/ IN WAKE OF DRY SFC HIGH THAT HAS
BEEN ESTABLISHED OVER THE AREA FOR MOST OF THIS WEEK. REGIONAL RADAR
SHOWS DECAYING ECHOES OVER NORTHERN WISCONSIN. MUCH MORE ORGANIZED
AREA OF SHRA/TSRA HAVE DEVELOPED SINCE 03Z FROM CENTRAL MINNESOTA
INTO WEST CENTRAL WISCONSIN ALONG H85 WARM FRONT/GRADIENT OF H85
THETA-E. ADDITIONAL AREA OF SHRA/TSRA SPREADING ACROSS NORTHEAST
SOUTH DAKOTA INTO SOUTHEAST NORTH DAKOTA NEAR CONVECTIVE INDUCED
SHORTAVE/H7-H3 DIFFERENTIAL PVA AND CLOSE TO H7 MOISTURE TRANSPORT.
JUST RECENTLY ANOTHER LARGE CLUSTER OF SHRA/TSRA HAVE FORMED IN THE
WARM AIR ADVECTION REGIME BTWN THESE TWO INITIAL AREAS OF PRECIP.
GIVEN EXTENT OF SHRA/TSRA UPSTREAM OF CWA THIS MORNING AND SINCE
H85-H7 MOISTURE ADVECTION IS FORECAST WEST TO EAST ACROSS CWA
THROUGH THE DAY...INCREASED POPS FOR MOST OF THE WEST AND NORTHERN
CWA AS AT LEAST MULTIPLE REMNANTS OF THIS CONVECTION SHOULD MAKE IT
INTO UPR MICHIGAN. LEANED ON THE NCEP WRF MODELS AND RECENT HRRR AND
EXTRAPOLATION OF LATEST HRRR TO CREATE POPS. RESULT IS LIKELY POPS
MOST OF THE DAY OVER THE WEST HALF...WITH SMALLER CHANCES FARTHER
EAST AS THE RAIN RUNS INTO THE VERY DRY AIRMASS ASSOCIATED WITH SFC
HIGH TO THE EAST. MAJORITY OF TSRA THUS FAR STAYING OVER NORTHERN
MINNESOTA ON GRADIENT OF 1-6KM MUCAPE RESERVOIR. HINT IN MODELS
THAT EASTERN EDGE OF INSTABILITY GRADIENT SLIDES TOWARD WESTERN UPR
MICHIGAN SO HAVE INCLUDED SLIGHT CHANCES FOR TSRA. CONVECTION IS
ELEVATED AND MID-LEVEL LAPSE RATES BARELY GET ABOVE 6C/KM. MAIN
ISSUE WILL BE HEAVY DOWNPOURS AND LIGHTNING STRIKES. TEMPS TODAY
A BIT TOUGH TO FIGURE OUT. EAST GRADIENT WINDS SHOULD KEEP KEWEENAW
CHILLY WITH READINGS STAYING BLO 50 DEGREES. MIXING TO H9 IS PROBABLY
IT WHERE CLOUDS/RAIN PERSIST MOST OF THE DAY. THIS SUPPORTS MAJORITY
OF CWA SEEING HIGHS IN THE 60S...EVENTUALLY...ONCE THE STEADIER RAIN
TAPERS OFF THIS AFTN. SFC WARM FRONT MAY TRY TO POKE INTO FAR SW CWA
LATE IN THE DAY. IF THIS OCCURS AND PRECIP TAPERS OFF/ENDS...THEN
THERE IS POTENTIAL FOR HIGHS TO PUSH WELL INTO THE 70S FROM IWD TO
IMT.
H85 FRONT LIFTS NORTH OF MOST CWA THIS EVENING. KEWEENAW STILL CLOSE
ENOUGH TO FRONT AND WITHIN THE RIBBON OF PERSISTENT MOISTURE
ADVECTION SO KEPT SHRA/ISOLD TSRA THERE THROUGH THE EVENING. DRYING
TREND TAKES HOLD OVERNIGHT AS THE FOCUS FOR SHRA/TSRA...H85 WARM
FRONT AND THETA-E GRADIENT...LIFTS WELL TO NORTH OF UPR MICHIGAN.
KEPT SMALL POPS IN AT ISLE ROYALE LATE TONIGHT THOUGH. TEMPS MOSTLY
IN THE 40S EAST WITH FLOW OFF LK MICHIGAN. LESS MODIFIED AIR FARTHER
WEST ALLOWS MINS TO ONLY FALL INTO THE LOW-MID 50S ALONG LK SUPERIOR
AROUND IWD TO ONTONAGON AND EAST TO BARAGA/L`ANSE AND MARQUETTE
AREAS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 510 AM EDT SAT MAY 18 2013
NAM SHOWS THE 500 MB RIDGE OVER THE EASTERN U.S. 12Z SUN WITH
TROUGHING IN THE ROCKIES. THE TROUGH MOVES EAST ON SUNDAY AND PUSHES
THE RIDGE INTO THE LOWER GREAT LAKES 12Z MON WHERE THE MOVEMENT
EASTWARD STOPS THROUGH 12Z TUE. NAM HAS SOME DEEPER MOISTURE AND
850-500 MB Q-VECTOR CONVERGENCE OVER THE AREA 12Z SUN ONWARD. GFS
SHOWS ABOUT THE SAME THING AS WELL.
THIS PERIOD LOOKS PRETTY WET STARTING WITH SUN AFTERNOON THROUGH MON
NIGHT. WITH SLOW MOVEMENT OF SYSTEM INTO AND THROUGH THE AREA AND
ALSO A WARM FRONT NEAR AND TO THE SOUTH OF THE AREA...THIS SETS UP
THE CWA FOR A WIDESPREAD AND LONG LIVED RAIN EVENT WITH SOME HEAVY
RAIN POSSIBLE. AM FORECASTING ANYWHERE FROM .67 INCH OF QPF OVER THE
SOUTH...TO 1.15 INCHES OVER THE EAST TO OVER 2 INCHES OF RAIN IN THE
FAR WEST NEAR IRONWOOD FROM SUNDAY AFTERNOON THROUGH MONDAY NIGHT
AND THIS DOES NOT SEEM UNREASONABLE WITH PLENTY OF MOISTURE TO THE
SOUTH OF THE AREA AND SLOW SYSTEM MOVEMENT. FOR THIS REASON...BUMPED
POPS UP A BIT TO LIKELY TO CATEGORICAL FOR MOST OF THE CWA THROUGH
THEN. SHOULD SEE SOME SUNSHINE ON SUNDAY. MADE A FEW ADJUSTMENTS TO
TEMPERATURES BASED ON LAKE BREEZES AND WIND DIRECTIONS AND LOWERED
THEM A BIT NEAR THE GREAT LAKES SHORELINES. OTHER THAN THAT...NO
REAL BIG CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB CLOSED LOW AND TROUGH
IN THE NORTHERN AND CENTRAL PLAINS 12Z TUE WHICH MOVE LITTLE INTO
12Z WED. BY 12Z THU...THE TROUGH AND LOW GET PUSHED A BIT FURTHER
EAST TO THE UPPER GREAT LAKES REGION. THE TROUGH AND LOW MOVE
THROUGH BY 12Z FRI WITH RIDGING BUILDING INTO THE PLAINS LATE ON
FRI. SYSTEM WILL BE SLOW TO MOVE THROUGH THE AREA...SO A COUPLE OF
DAYS OF WIDESPREAD RAIN ARE NOT OUT OF THE QUESTION ALONG WITH
COOLER TEMPERATURES WITH GRADUAL SOUTHWARD MOVEMENT OF THE SYSTEM
AWAY FROM THE AREA. THU INTO FRI...THINGS START TO DRY OUT WITH A
COLD FRONT WELL SOUTH OF THE AREA. TEMPERATURES SLIP TO SLIGHTLY
BELOW NORMAL THIS PERIOD. POPS WILL BE HIGHEST IN THE SOUTH CLOSER
TO A WARM FRONT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 747 AM EDT SAT MAY 18 2013
A WARM FNT MOVING IN FM THE SOUTH WILL BRING SOME -SHRA/MVFR
CIGS...MAINLY AT IWD/CMX WHERE LLVL WARM/MOIST ADVCTN WL BE MOST
PRONOUNCED. MOIST UPSLOPE FLOW OFF LK SUPERIOR MAY RESULT IN IFR
CONDITIONS AT CMX THIS AFTN AND EVENING. FOLLOWING THE WARM FROPA
TONIGHT...EXPECT WSHFT TO THE S WITH RETURN TO PREDOMINANT VFR WX.
THE ONLY EXCEPTION WL BE AT CMX...WHERE PERSISTENT UPSLOPE ESE WIND
AND MOISTER LLVL AIR WL RESULT IN LINGERING MVFR CONDITIONS THROUGH
MUCH OF THE NIGHT. &&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT SAT MAY 18 2013
HEADING THRU EARLY NEXT WEEK...THE PRESSURE GRADIENT OVER THE UPPER
LAKES WILL SLOWLY TIGHTEN BETWEEN LOW PRESSURE SLOWLY MOVING FROM
THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRESSURE
BUILDING IN THE VICINITY OF WRN HUDSON BAY. THIS WILL LEAD TO
EASTERLY WINDS GRADUALLY INCREASING TO ALMOST 30 KNOTS BY MON AND
MON NIGHT...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...07
AVIATION...JLA
MARINE...07
AREA FORECAST DISCUSSION
NWS BILLINGS MT
919 AM MDT SAT MAY 18 2013
.UPDATE...
HAVE MADE SOME CHANGES TO THE MORNING FORECAST. GFS/ECMWF/NAM12
ARE IN GOOD AGREEMENT IN LIFTING ANOTHER WAVE ACROSS THE AREA THIS
MORNING. RADAR RETURNS HAVE BEEN INCREASING OVER SOUTH CENTRAL
MONTANA THIS MORNING WITH UPPER JET BRINGING A SHORT WAVE INTO THE
AREA ALONG WITH INCREASING QG FORCING. A FEW EMBEDDED
THUNDERSHOWERS ALSO POSSIBLE WITH WEAK LOW LEVEL INSTABILITY. HAVE
RAISED POPS TO LIKELY FROM BILLINGS WEST FOR THIS MORNING. LOWERED
POPS IN THE EAST FOR THIS MORNING AS FORCING FROM THE UPPER LEVEL
TROUGH WILL NOT IMPACT SOUTHEAST MONTANA UNTIL AFTER 18Z TODAY.
PATCHY FOG ACROSS THE AREA IS QUICKLY LIFTING AND WILL REMOVE IT
FROM THE FORECAST. NO CHANGES TO TEMPERATURE FORECAST THEY LINE UP
WELL WITH CURRENT GUIDANCE. RICHMOND
&&
.SHORT TERM...VALID FOR TDY AND SUN...
RAINFALL TOTALING AN INCH OR MORE STILL LOOKS LIKE A GOOD BET OVER
THE NEXT FEW DAYS IN MANY AREAS. HOWEVER...THE 500-HPA TROUGH THAT
IS SET TO DRIVE ONE OF THE BETTER PRECIPITATION EVENTS WE HAVE HAD
IN A LONG TIME IS SURPRISING COMPLEX...SO SOME UNCERTAINTY EXISTS.
TODAY...THE MID-LEVEL SHORT WAVE TROUGH CENTERED NEAR 700 HPA THAT
IS SEEN ENTERING WESTERN WY ON 09 UTC MOISTURE CHANNEL IMAGES WILL
MOVE INTO SOUTHERN MT. THE ECMWF HAS BEEN THE MOST CONSISTENT WITH
BRINGING THIS BATCH OF FORCING INTO THE AREA IN THE LAST FEW DAYS.
ITS 00 UTC RUN CONTINUES THIS THEME...GENERATING CONVECTION ACROSS
MUCH OF THE AREA AFTER 18 UTC...WITH QPF AMOUNTS OF A QUARTER TO A
HALF INCH. THE 00 UTC GFS HAS FINALLY PICKED UP ON THIS SHORT WAVE
TOO...SO OUR CONFIDENCE IN PRECIPITATION HAS INCREASED ENOUGH THAT
WE HAVE CHOSEN TO ADVERTISE 90 TO 100 PERCENT POPS AFTER 18 UTC IN
THE BILLINGS...SHERIDAN...MILES CITY...AND BROADUS AREAS. THE 700-
500 HPA LAPSE RATES ARE MODEST AROUND 6 C/KM...BUT THERE IS ENOUGH
INSTABILITY /POCKETS OF MUCAPE UP TO 500 J/KG/ TO GENERATE THUNDER
AS WELL. CALIBRATED THUNDERSTORM PROBABILITIES OFF THE 03 UTC SREF
JUMP UP INTO THE 40 AND 50 PERCENT RANGE AFTER 18 UTC AS WELL. THE
SEVERE RISK IS NEGLIGIBLE THOUGH GIVEN THE EXPECTED INSTABILITY. A
CAUTIONARY NOTE ABOUT THE POP FORECAST IS THAT MANY WRF-BASED HIGH
RESOLUTION MODELS FROM 00 UTC CLUSTER CONVECTION FURTHER SOUTHEAST
FROM SHERIDAN TOWARD BROADUS...WHICH MAY ACTUALLY SUPPRESS SOME OF
THE PRECIPITATION FURTHER NORTH IN PLACES LIKE BILLINGS. NOTE THAT
WE ALSO DECIDED TO CARRY ONLY CHANCE POPS IN MANY PLACES BEFORE 18
UTC BASED ON UPSTREAM TRENDS AND RECENT RAP AND HRRR OUTPUT.
TONIGHT...WE CONTINUED LEANING ON THE 00 UTC ECMWF SOLUTION DURING
THE EVENING...WITH A CONCENTRATED AREA OF CATEGORICAL POPS FOR THE
PLAINS OF SOUTH CENTRAL AND SOUTHEASTERN MT BEFORE 06 UTC. WE THEN
LET POPS FALL BACK A BIT AFTER MIDNIGHT IN MANY AREAS SINCE 1/ THE
DIURNALLY-DRIVEN CONVECTION SHOULD DIMINISH WITH SUNSET...AND 2/ A
BREAK IN FORCING SHOULD TAKE PLACE AS THE 700-HPA SHORT WAVE MOVES
OUT AND/OR WEAKENS. IF THE ECMWF IS CORRECT...WE MAY ACTUALLY HAVE
A RELATIVELY DRY PERIOD AFTER 06 UTC. HOWEVER...THE 00 UTC GFS AND
EVEN THE 03 UTC SREF KEEP MORE STRATIFORM-BASED PRECIPITATION OVER
SOUTH CENTRAL MT AND NORTH CENTRAL WY RIGHT THROUGH THE NIGHT...SO
WE WERE CAUTIOUS ABOUT LOWERING POPS BELOW THE LIKELY THRESHOLD AT
THIS POINT. WE ALSO KEPT IN ISOLATED THUNDERSTORMS FOR MOST OF THE
AREA AFTER 06 UTC...BUT WE MIGHT BE ABLE TO DROP THAT MENTION WITH
LATER FORECASTS SINCE MUCAPE AND THE SREF THUNDERSTORM PROBABILITY
VALUES BOTH DWINDLE NOCTURNALLY.
ON SUN...A 500-HPA TROUGH IS EXPECTED TO CLOSE OFF...LIKELY ACROSS
WY...AND THAT SHOULD DRIVE A MORE STEADY RAIN EVENT ACROSS PART OR
EVEN ALL OF THE AREA. THIS IS THE POINT WHERE COMPLEX INTERACTIONS
OF SHORT WAVES AND CONVECTION WITHIN THE LARGER-SCALE TROUGH COULD
ULTIMATELY DICTATE WHERE AND HOW MUCH RAIN FALLS. WE INCREASED THE
POPS ONE MORE TIME THOUGH SO THAT THEY ARE CATEGORICAL FOR MUCH OF
THE AREA SINCE THERE IS FAIR AGREEMENT AMONG 00 UTC MODELS. LIKELY
AND CATEGORICAL POPS CONTINUE INTO SUN NIGHT.
HYDROLOGY-WISE...WE DECIDED TO LET GO OF THE FLASH FLOOD WATCH FOR
THE BURN SCAR AREAS WITH THIS FORECAST RELEASE. THE RAINFALL RATES
OVER THE NEXT FEW DAYS ARE NOT EXPECTED TO BE LARGE ENOUGH TO NEED
AN EXTENSION OF THE WATCH...THOUGH WE WILL CERTAINLY BE KEEPING AN
EYE ON THOSE BURN SCAR AREAS REGARDLESS. OTHERWISE...THERE WILL BE
AT LEAST MINOR RISES ON AREA RIVERS AND STREAMS IN THE COMING DAYS
IF THE FORECAST PRECIPITATION AMOUNTS COME TO FRUITION. HOWEVER...
NO FLOODING IS EXPECTED BECAUSE OUR VERY DRY SOILS WILL BE ABLE TO
EASILY ABSORB MUCH OF THE MOISTURE. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE EXTENDED PERIOD STARTS ON MONDAY AND MODEL DIFFERENCES MUDDY
THE WATERS ON TIMING OF PRECIPITATION TAPERING OFF OVER THE AREA.
BOTH MODELS MOVE THE UPPER LOW THAT WILL IMPACT THE AREA THIS
WEEKEND INTO EASTERN SOUTH DAKOTA BY 00Z TUESDAY. THE GFS BUILDS
THE RIDGE IN MUCH MORE AGGRESSIVELY AND SENDS WRAP AROUND ENERGY
AND MOISTURE SOUTH INTO WYOMING. THE ECMWF...HOWEVER...WAS SLOWER
WITH BUILDING HEIGHTS AND THIS ALLOWS ENERGY TO WRAP BACK INTO
EASTERN AND CENTRAL ZONES MONDAY. WILL SIDE WITH THE ECMWF AS THIS
WAS THE CONSENSUS OF SURROUNDING OFFICES AS OFTEN TIMES THESE
SLOW MOVING UPPER LOWS ARE SLOWER TO DRY OUT THAN MODELS EXPECT.
SHOULD GET DRYING CONDITIONS FOR TUESDAY AS THE RIDGE BUILDS IN
EARNEST. THE NEXT UPPER LOW...WHICH IS PROGGED TO BE QUITE A BIT
DEEPER THAN ITS PREDECESSOR...MOVES INLAND WEDNESDAY. ENERGY DOES
SWING AROUND THE UPPER LOW AND DRIVES ACROSS WESTERN AND CENTRAL
ZONES WEDNESDAY AND THURSDAY. LOW LEVEL WINDS WILL BE EASTERLY AND
THIS SHOULD ALLOW DEWPOINTS TO BE ON THE RISE. DRIER AIR WILL GET
PULLED INTO THE SYSTEM BUT THE GFS HAS BACKED OFF ON THIS FROM
YESTERDAY. CAPES SHOULD INCREASE WITH EASTERLY WINDS INCREASING
LOW LEVEL DEWPOINTS. RAISED POPS OVER WESTERN AND CENTRAL ZONES
FOR AFTERNOON AND EVENING CONVECTION WEDNESDAY AND THURSDAY. WILL
HAVE TO WATCH FOR A POTENTIAL DRY SLOT TO LIMIT CONVECTION...BUT
AS LONG AS THE MODELS KEEP THE WINDS EAST...NEED TO HAVE POPS IN
THERE. TEMPERATURES WILL MODERATE FROM THE LOWER 60S MONDAY TO THE
LOWER 70S TUESDAY AND HOLD AROUND THAT LEVEL THROUGH THE REST OF
THE WEEK. TWH
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS THIS MORNING...MAINLY SOUTH
OF A KBIL TO KLVM LINE...CONTINUE TO EXPAND AND MOVE
NORTHEAST...AND WILL BECOME MORE WIDESPREAD THROUGH THE DAY. THE
PRECIP WILL CONTINUE TO MOVE SLOWLY NORTHEAST AND SHIFT OUT OF THE
AREA OVERNIGHT. SOME OF THE STORMS WILL CONTAIN MODERATE TO
BRIEFLY HEAVY RAINFALL AND COULD LOWER CONDITIONS TO MVFR. PATCHY
FOG REPORTED EAST OF A KBIL TO KSHR LINE IS LIFTING...AND SHOULD
CLEAR OUT BY LATE MORNING. MOUNTAINS WILL BE OBSCURED IN SHOWERS
AND CLOUDS THROUGHOUT THE DAY. AAG/TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 062 048/058 048/062 045/071 047/071 049/071 049/076
+/T 88/T 86/W 31/B 13/T 42/T 22/T
LVM 060 041/057 040/059 037/066 041/071 040/067 041/071
8/T 77/T 85/W 31/B 14/T 43/T 33/T
HDN 064 048/062 047/062 044/071 045/073 049/074 048/078
+/T 98/T 86/W 31/E 12/T 32/T 22/T
MLS 068 051/063 049/062 046/068 046/071 050/071 048/075
+/T +8/T 86/W 53/W 22/T 22/T 22/T
4BQ 069 048/059 047/060 043/063 044/071 048/071 047/075
+/T +8/T 87/W 53/W 11/B 22/T 21/B
BHK 068 048/060 047/060 043/061 043/067 048/067 048/070
8/T +8/T 86/W 53/W 21/B 22/T 22/T
SHR 065 047/056 043/057 040/064 040/073 046/072 045/076
9/T 67/T 86/W 42/W 12/T 32/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1038 AM CDT SAT MAY 18 2013
.MESOSCALE DISCUSSION...
ISSUED AT 1019 AM CDT SAT MAY 18 2013
SEVERE THUNDERSTORM POTENTIAL STILL ON TRACK THIS AFTERNOON AND
EVENING. LATEST HAND SFC ANALYSIS HAS A 1004 MB SFC LOW PRESSURE
CENTER TO THE EAST OF LA JUNTA COLORADO...WITH A DRY LINE
EXTENDING SOUTH FROM THE LOW CENTER THROUGH THE TX PANHANDLE AND
WARM FRONT EAST NORTHEAST ACROSS NORTHERN KS. SFC LOW SHOULD LIFT
NORTH TO NEAR GOODLAND BY LATE AFTERNOON...WITH A WARM FRONT
ARCING NORTHEAST INTO SOUTHWEST NEBRASKA. THUNDERSTORMS SHOULD
INITIATE AROUND IMPERIAL AND HAYES CENTER BY MID TO LATE AFTERNOON
ON NOSE OF VERY STEEP LOW LEVEL LAPSE RATES/DRY LINE WHICH WILL BE
PUNCHING INTO FAR SOUTHWEST NEBRASKA. STORMS LIKELY TO BECOME
SUPERCELLS QUICKLY AS THEY MOVE NORTHEAST INTO A VERY TO EXTREMELY
UNSTABLE AND FAVORABLE SHEARED ATMOSPHERE. BACKED WINDS TO THE
SOUTHEAST ARE EXPECTED ACROSS MOST OF SOUTHWEST
NEBRASKA...ENHANCING THE THREAT FOR TORNADO DEVELOPMENT. IN
ADDITION TO THE TORNADO THREAT...VERY LARGE HAIL...POSSIBLE BASEBALL
SIZE OR LARGER...IS EXPECTED. STORMS WILL LIKELY MERGE EARLY THIS
EVENING INTO A COMPLEX AS THEY ADVANCE NORTHEAST TOWARD CENTRAL
AND NORTH CENTRAL NEBRASKA. LARGE HAIL AND DAMAGING WINDS WILL BE
THE MAIN THREATS FROM THE COMPLEX.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 616 AM CDT SAT MAY 18 2013
MVFR CIGS SHOULD ERODE WITH VFR DEVELOPING BETWEEN 17Z-19Z. SEVERE
STORMS COULD BEGIN DEVELOPING ACROSS SWRN NEB VCNTY KIML AROUND
20Z-22Z. STORM ACTIVITY WILL LIFT NORTH AND EAST THROUGH THE
EVENING HOURS. VFR COULD DEVELOP FROM WEST TO EAST BEGINNING
AROUND 03Z IN THE NEB PANHANDLE TO 09Z IN THE EAST SIDE OF THE
FCST AREA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...TAYLOR
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
619 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 616 AM CDT SAT MAY 18 2013
MVFR CIGS SHOULD ERODE WITH VFR DEVELOPING BETWEEN 17Z-19Z. SEVERE
STORMS COULD BEGIN DEVELOPING ACROSS SWRN NEB VCNTY KIML AROUND
20Z-22Z. STORM ACTIVITY WILL LIFT NORTH AND EAST THROUGH THE
EVENING HOURS. VFR COULD DEVELOP FROM WEST TO EAST BEGINNING
AROUND 03Z IN THE NEB PANHANDLE TO 09Z IN THE EAST SIDE OF THE
FCST AREA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1046 AM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 1024 AM CDT SAT MAY 18 2013
THE TIMING AND LOCATION OF CONVECTIVE INITIATION IN THIS COMPLEX
SCENARIO IS THE MAIN FOCUS TODAY. PRECIPITATION CHANCES ALONG THE
MISSOURI RIVER HAVE GENERALLY BEEN LOWERED FOR THIS MORNING AND
EARLY AFTERNOON AS LOW LEVEL STRATUS WILL HELP TO STABILIZE THE
ATMOSPHERE UNTIL THE NEXT MID LEVEL SHORTWAVE ARRIVES THIS
AFTERNOON.
THE 12 AND 13 UTC HRRR HAVE PICKED UP ON THE CLEARING OVER
NORTHWESTERN SOUTH DAKOTA THIS MORNING...AND NOW INITIATES
CONVECTION THERE AND IN SOUTHWESTERN NORTH DAKOTA BY 21 UTC. 12
UTC GFS THERMODYNAMIC PROFILES SUPPORT THIS IDEA ALONG WITH THE 00
UTC ECMWF AS CAPE IS FORECAST TO EXCEED 1000 J/KG THERE.
THE CURRENT THINKING IS THAT CONVECTION WILL SPREAD GENERALLY
EAST-NORTHEASTWARD UNTIL MID/LATE AFTERNOON DESTABILIZATION AND
MIDDLE LEVEL HEIGHT FALLS FINALLY INITIATE ADDITIONAL CONVECTION
BETWEEN THE MISSOURI AND JAMES RIVERS ALONG THE DAKOTA BORDER.
UPDATE ISSUED AT 644 AM CDT SAT MAY 18 2013
UPDATE MAINLY FOR POP TRENDS TODAY. SHOWERS AND ISOLATED STORMS
HAVE PUSHED INTO THE FAR NORTHEAST EARLY THIS MORNING. RECENT RUNS
OF THE RAP HAVE A GOOD HANDLE ON NEAR TERM TRENDS...AND HAVE
REDUCED POPS THROUGH THE MORNING INTO EARLY AFTERNOON. STILL
EXPECTING THE FOCUS OF AFTERNOON CONVECTION ALONG A BOUNDARY TO
THE SOUTHEAST...WITH POTENTIAL FOR SOME SEVERE STORMS TO DEVELOP
BY MID AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1024 AM CDT SAT MAY 18 2013
LOW STRATUS HAS BEEN VERY DIFFICULT TO FORECAST THIS MORNING...BUT
SHOULD IMPROVE BY 18 UTC. SHOWERS AND THUNDERSTORMS WILL CAUSE
MVFR CONDITIONS AT MOST TAF SITES TODAY...WITH BRIEF PERIODS OF
IFR POSSIBLE IN STRONGER STORMS. FOG AND LOW STRATUS WILL LIKELY
RETURN AFTER MIDNIGHT TONIGHT IN THE WAKE OF PRECIPITATION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...SCHECK
SHORT TERM/LONG TERM...RP KINNEY
AREA FORECAST DISCUSSION
NWS BISMARCK ND
644 AM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 644 AM CDT SAT MAY 18 2013
UPDATE MAINLY FOR POP TRENDS TODAY. SHOWERS AND ISOLATED STORMS
HAVE PUSHED INTO THE FAR NORTHEAST EARLY THIS MORNING. RECENT RUNS
OF THE RAP HAVE A GOOD HANDLE ON NEAR TERM TRENDS...AND HAVE
REDUCED POPS THROUGH THE MORNING INTO EARLY AFTERNOON. STILL
EXPECTING THE FOCUS OF AFTERNOON CONVECTION ALONG A BOUNDARY TO
THE SOUTHEAST...WITH POTENTIAL FOR SOME SEVERE STORMS TO DEVELOP
BY MID AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 430 AM CDT SAT MAY 18 2013
AREA OF SHOWERS AND SCATTERED THUNDERSTORMS CONTINUE TO PUSH
NORTH AND EAST AS A MID LEVEL DISTURBANCE LIFTS NORTHEAST ACROSS
CENTRAL NORTH DAKOTA EARLY THIS MORNING. PRECIPITATION HAS ENDED
AT KBIS-KDIK-KISN...AND WILL END BY 15Z FOR KMOT-KJMS. HIGH LOW
LEVEL MOISTURE WILL RESULT IN AREAS OF FOG AND POSSIBLE VLIFR
STRATUS THIS MORNING AT MOST IF NOT ALL TERMINALS. WHILE THE
STRATUS AND FOG SHOULD LIFT BY MID MORNING...IT MAY LINGER AT KMOT
INTO SATURDAY AFTERNOON...THEN DEVELOP OVER ALL TERMINALS ONCE
AGAIN SATURDAY NIGHT.
SHOWERS AND THUNDERSTORMS WILL REDEVELOP AFTER 18Z SATURDAY
AFTERNOON...DEVELOPING NORTH AND EAST INTO SATURDAY NIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/SHORT TERM/LONG TERM...RP KINNEY
AVIATION...NH
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1104 AM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 1104 AM CDT SAT MAY 18 2013
GOING FORECAST IS IN GOOD SHAPE. INCREASED THE SKY COVER A BIT IN
OUR WESTERN AND NORTHERN ZONES THROUGH EARLY AFTERNOON AS VERY
LIGHT CONVECTION CONTINUES TO DIE IN THOSE AREAS. THIS MAY IMPACT
HIGH TEMPERATURES A LITTLE BIT. FOR NOW...SHAVED DOWN HIGHS AROUND
A CATEGORY THROUGHOUT THE NORTHWEST HALF OF OUR AREA AS
TEMPERATURES ARE STILL IN THE 60S TO AROUND 70 UNDERNEATH THE
CLOUD COVER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 627 AM CDT SAT MAY 18 2013
SHOWERS AND THUNDERSTORMS IN SOUTH CENTRAL SD EXPECTED TO DIMINISH BY
AROUND 15Z. COULD SEE A FEW GUSTS TO AROUND 35KT WITH THUNDERSTORMS
IN THE KHON AREA THIS MORNING. ALSO WATCHING A BAND OF MVFR STRATUS
ACROSS WESTERN AND CENTRAL NEBRASKA WHICH IS SPREADING NORTHEAST THIS
MORNING. EXPECT THIS BAND TO LARGELY DISSIPATE THROUGH MID/LATE
MORNING AS IT APPROACHES IT MISSOURI VALLEY...WITH LITTLE TO NO IMPACT
IN OUR FORECAST AREA. OTHERWISE...EXPECT SHOWERS AND STORMS TO PUSH
IN SOUTH CENTRAL SD AFTER 00Z AND BECOME MORE WIDESPREAD AND THEY
TRACK EAST INTO THE I29 CORRIDOR AROUND 06Z. STRONG TO SEVERE STORMS
WILL BE POSSIBLE THIS EVENING AND OVERNIGHT WITH LARGE HAIL...GUSTS
TO 70 MPH POSSIBLE. BEST THREAT FOR LARGE HAIL WILL OCCUR FROM 00Z TO
06Z AND MAY TRANSITION TO MORE A DAMAGING WIND THREAT LATE EVENING
AND OVERNIGHT. MVFR/IFR CEILINGS POSSIBLE IN STRONGER STORMS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...MJF
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
639 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 627 AM CDT SAT MAY 18 2013
SHOWERS AND THUNDERSTORMS IN SOUTH CENTRAL SD EXPECTED TO DIMINISH BY
AROUND 15Z. COULD SEE A FEW GUSTS TO AROUND 35KT WITH THUNDERSTORMS
IN THE KHON AREA THIS MORNING. ALSO WATCHING A BAND OF MVFR STRATUS
ACROSS WESTERN AND CENTRAL NEBRASKA WHICH IS SPREADING NORTHEAST THIS
MORNING. EXPECT THIS BAND TO LARGELY DISSIPATE THROUGH MID/LATE
MORNING AS IT APPROACHES IT MISSOURI VALLEY...WITH LITTLE TO NO IMPACT
IN OUR FORECAST AREA. OTHERWISE...EXPECT SHOWERS AND STORMS TO PUSH
IN SOUTH CENTRAL SD AFTER 00Z AND BECOME MORE WIDESPREAD AND THEY
TRACK EAST INTO THE I29 CORRIDOR AROUND 06Z. STRONG TO SEVERE STORMS
WILL BE POSSIBLE THIS EVENING AND OVERNIGHT WITH LARGE HAIL...GUSTS
TO 70 MPH POSSIBLE. BEST THREAT FOR LARGE HAIL WILL OCCUR FROM 00Z TO
06Z AND MAY TRANSITION TO MORE A DAMAGING WIND THREAT LATE EVENING
AND OVERNIGHT. MVFR/IFR CEILINGS POSSIBLE IN STRONGER STORMS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1056 AM CDT SAT MAY 18 2013
.UPDATE...
12Z FWD SOUNDING SHOWS MOISTURE DEPTH HAS BEEN REDUCED AS COMPARED
TO YESTERDAY...WHICH SHOULD CAUSE DEWPOINTS TO MIX OUT INTO THE
LOW 60S WEST TO MID 60S CENTRAL AND EAST. IN ADDITION...THE LOW
LEVEL THERMAL PROFILE HAS WARMED A FEW DEGREES OVER YESTERDAY
WHICH MEANS HIGH TEMPS WILL BE A COUPLE DEGREES WARMER TODAY FOR
MOST AREAS. LIGHT ECHOES IN THE SOUTHWEST CWA THIS MORNING ARE
ASSOCIATED WITH WEAK MID LEVEL CONVECTION AND PRECIP IS LIKELY NOT
REACHING THE GROUND. PREVIOUS FORECAST WAS GENERALLY ON TRACK AND
A JUST A FEW CHANGES TO HOURLY GRIDS WERE MADE FOR TRENDS.
CONCERNING THE CONVECTIVE POTENTIAL FOR THIS AFTERNOON AND
EVENING...IT STILL APPEARS THE WESTERN AND NORTHWESTERN COUNTIES
HAVE SOME THREAT OF SEVERE STORMS BUT THERE ARE SOME MIXED
SIGNALS IN THE DATA TODAY. THE STRONG CAP WILL CONTINUE TO BE THE
PRIMARY IMPEDANCE FOR CONVECTIVE ACTIVITY. A LOWER MOISTURE DEPTH
MAY RESULT IN DEWPOINTS MIXING OUT MORE THAN FORECAST WHICH WOULD
KEEP CIN VALUES TOO HIGH. THE DRYLINE WILL ALSO BE POSITIONED
FARTHER WEST TODAY AND ALONG A LINE FROM VERNON TO SAN ANGELO.
HOWEVER...THE MODEL DATA IS IN AGREEMENT THAT A WEAK SHORTWAVE
WILL MOVE ACROSS THE NORTHWEST ZONES THIS EVENING AND RESULT IN
HEIGHT FALLS. THIS BIT OF FORCING WOULD HELP TO ERODE THE CAP AND
WOULD FAVOR CONVECTIVE INITIATION OCCURRING TO THE WEST OF THE CWA
LATE THIS AFTERNOON. MID LEVEL WESTERLY WIND FIELDS ARE SLIGHTLY
STRONGER TODAY AND STORMS WOULD HAVE THE POTENTIAL TO MOVE MORE
EASTERLY AND INTO THE WESTERN CWA BY EARLY THIS EVENING. THE RUC
KEEPS ALL ACTIVITY TO OUR WEST...BUT THE HRRR AND 12Z NAM ARE
BRINGING IT INTO THE WESTERN ZONES. SOME OF THE OTHER HI-RES
MODELS ARE NOT EVEN INITIATING...SO AGAIN POPS WILL BE GENERALLY
JUST 20 PERCENT WEST OF A GAINESVILLE TO MINERAL WELLS TO
GOLDTHWAITE DUE TO INITIATION AND STORM MOTION UNCERTAINTIES. DUE
TO STEEP LAPSE RATES...INSTABILITY WILL BE HIGH WITH CAPES LIKELY
OVER 3000 J/KG AT PEAK HEATING...AND THE MAIN SEVERE THREAT IN OUR
CWA WILL BE LARGE HAIL. ACROSS THE CENTRAL AND EASTERN ZONES THE
CAP WILL REMAIN TOO STRONG FOR SURFACE BASED CONVECTION...BUT
THESE AREAS MAY EXPERIENCE SPRINKLES AND GUSTY WINDS FROM STORM
ANVILS LATER THIS EVENING.
TR.92
&&
.AVIATION...
/12Z TAFS/
CONCERNS...NOCTURNAL STRATUS AND THUNDERSTORMS TO THE WEST.
STRATUS HAS SLOWLY MADE ITS WAY UP THE I-35 CORRIDOR OVERNIGHT. A
SIGNIFICANT WESTERLY COMPONENT ABOVE THE STRATUS IS REDUCING THE
DEPTH OF THE LAYER AND SHOULD KEEP THE DECK SOUTH AND EAST OF
METROPLEX TAF SITES.
ISOLATED THUNDERSTORMS MAY DEVELOP ACROSS WESTERN PORTIONS OF
NORTH TEXAS LATE THIS AFTERNOON. SOME OF THE ACTIVITY MAY APPROACH
THE I-35 CORRIDOR THIS EVENING. MAY IMPACT WEST DEPARTURES AND
NORTHWEST ARRIVALS...BUT DO NOT ANTICIPATE ANY ISSUES AT TAF
SITES.
A MORE VIGOROUS LLJ SUNDAY MORNING SHOULD IMPROVE THE PROBABILITY
OF MORNING STRATUS.
25
&&
.SHORT TERM...
A SHORTWAVE DISTURBANCE WAS SEEN VIA WATER VAPOR SATELLITE IMAGERY
EARLY THIS MORNING ROTATING THROUGH CENTRAL/EASTERN NEW MEXICO.
THIS FEATURE WILL EJECT WITHIN INCREASING SOUTHWEST FLOW ALOFT
ACROSS WEST TX/OK BY AFTERNOON. THIS WILL DEEPEN AND MOVE THE
SURFACE DRYLINE INTO THE SOUTH PLAINS BY EARLY EVENING. LIFT FROM
BOTH OF THESE FEATURES WILL COMBINE WITH HIGH TEMPERATURES AROUND
100 DEGREES AND THE RESULTING VERY HIGH INSTABILITY FOR THE
DEVELOPMENT OF A FEW SUPERCELLS LATE IN THE DAY. THIS IS TYPICALLY
THE TIME OF THE YEAR/MID MAY-LATE JUNE/ THAT THE DRYLINE OUT WEST IS
THE MOST ACTIVE...USUALLY PRODUCING DIURNAL SEVERE WEATHER IN THE
LATE AFTERNOONS AND EARLY EVENINGS. EXPECT MORE DISCRETE SUPERCELLS
LATE TODAY AND THIS EVENING IN AND NEAR OUR FAR WESTERN COUNTIES.
CURRENT SHEAR AND BUNKERS METHOD INDICATE THERE WILL BE MORE
STEERING CURRENTS TO THE NORTHEAST VERSUS YESTERDAY WITH UPPER
TROUGH APPROACHING. HOWEVER...AS WITH ANY SUPERCELL DEVIANT
MOTIONS CANNOT BE RULED OUT ONCE ANY MESOCYCLONES DEVELOP WITHIN
THE STORMS THEMSELVES. DESPITE RELATIVELY HIGH LCLS WITH THE HOT
AND UNSTABLE AIRMASS...JUST ABOUT ALL TYPES OF SEVERE WEATHER WILL
BE POSSIBLE WITH THIS ACTIVITY. EXPECT ABOUT 20-30 PERCENT COVERAGE
OF SEVERE STORMS ACROSS THE NORTHWEST COUNTIES. THE INVERSION
STRENGTHENS ONCE AGAIN BY LATE EVENING AND EXPECT THE MAJORITY OF
ACTIVITY TO DIMINISH QUICKLY.
THE NEXT ROUND OF SEVERE WEATHER LATE SUNDAY WILL LIKELY BE MORE
ACROSS THE NORTHERN TIER COUNTIES VERSUS JUST THE WEST...AS A
NEGATIVE TILT SHORTWAVE DISTURBANCE ROTATES ACROSS THE TX/OK
PANHANDLES INTO WESTERN OK/KS. THE SURFACE DRYLINE WILL HAVE A
BETTER PUSH TO EAST ACROSS THOSE AREAS NORTH OF I-20 IN RESPONSE
TO THIS SHORTWAVE. THE HIGHER COVERAGE OF SEVERE WEATHER AND RISK
WILL BE OVER EASTERN OK INTO THE OZARKS...BUT SHOULD ZIPPER A FEW
STORMS SOUTH-SOUTHWEST ACROSS THE RED RIVER BY EVENING. ALL THREATS
WILL BE POSSIBLE ONCE AGAIN.
&&
.CLIMATE...
YESTERDAY (MAY 17) WAS THE FIRST 90-DEGREE DAY AT DFW AIRPORT THIS
YEAR. IT WAS ALSO THE FIRST TIME NORTH TEXAS HAS SEEN 100 DEGREES
IN 2013. GRAHAM HIT 101...AND BRECKENRIDGE PEAKED AT 104.
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 93 73 92 72 91 / 5 5 10 20 10
WACO, TX 92 71 91 73 90 / 5 5 10 10 10
PARIS, TX 88 70 87 68 87 / 5 5 5 20 10
DENTON, TX 93 72 90 72 90 / 5 10 10 20 10
MCKINNEY, TX 90 72 89 71 88 / 5 5 5 20 10
DALLAS, TX 93 73 91 74 91 / 5 5 10 20 10
TERRELL, TX 90 71 90 71 89 / 5 5 5 10 10
CORSICANA, TX 91 71 89 73 90 / 5 5 5 10 10
TEMPLE, TX 92 71 91 72 90 / 5 5 10 10 10
MINERAL WELLS, TX 96 70 94 69 95 / 5 20 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
606 AM CDT SAT MAY 18 2013
.DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
MID LEVEL CLOUD COVER WILL PERSIST THROUGH MID MORNING BEFORE
BEING REPLACED BY A HIGH BASED CU FIELD THAT WILL CONTINUE THROUGH
EARLY EVENING. WINDS WILL BE PREDOMINANTLY FROM THE SOUTH /170-200
DEGREES/ AND WILL INCREASE TO 15-20 KTS BY 14-15Z. I EXPECT WIND
SPEEDS TO STAY THROUGHOUT THE DAY. WINDS WILL STAY UP THIS EVENING
AT KABI/KSJT AS THE LOW LEVEL JET REDEVELOPS. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS WILL BE POSSIBLE ALONG AND EAST OF THE
DRYLINE. HOWEVER...COVERAGE SHOULD BE LIMITED SO NO THUNDER WAS
INCLUDED AT ANY PARTICULAR TAF SITE. HOWEVER...KABI AND KBBD STAND
THE BEST CHANCE OF SEEING THIS ACTIVITY /ALBEIT STILL A LOW
CHANCE/. WILL WAIT FOR THE DETAILS TO EMERGE BEFORE INCLUDING
RESTRICTIONS IN THE TAFS.
JOHNSON
&&
.PREV DISCUSSION... /ISSUED 417 AM CDT SAT MAY 18 2013/
SHORT TERM...
NEAR RECORD TEMPERATURES AND POTENTIAL SEVERE CONVECTION HIGHLIGHT
THE SHORT TERM PORTION OF THE FORECAST.
PRONOUNCED SOUTHWEST FLOW ALOFT IS EVIDENT PER 00Z UPPER AIR
ANALYSIS. SHORTWAVE RIDGING OVER THE PLAINS THAT HAS SHARED SOME
RESPONSIBILITY FOR OUR OPPRESSIVE HEAT WILL SHIFT SLOWLY EAST AS A
TROUGH MOVES ACROSS THE ROCKIES. THIS TROUGH IS TAKING ON
SOMEWHAT OF A NEGATIVE TILT BUT THE STRONGEST WINDS ALOFT REMAIN
ON ITS WESTERN FLANK. A SUBTROPICAL JET STREAK IS PROPAGATING
NORTHEAST ACROSS MEXICO THIS MORNING AND SHOULD ARRIVE THIS
EVENING. IN THE LOWER TROPOSPHERE...STRONG LEE CYCLOGENESIS HAS
ENHANCED THE NOCTURNAL LOW LEVEL JET WHICH IS CONTINUING TO PUMP
GULF MOISTURE NORTH INTO THE SOUTHERN PLAINS. DEWPOINTS ARE IN THE
60S TO LOWER 70S ACROSS THE CWA. THE DRYLINE IS CURRENTLY FOUND TO
OUR WEST AND WILL MOVE A BIT TO THE EAST TODAY. THE QUESTION
REMAINS HOW FAR EAST. MOST OF THE 00Z GUIDANCE MIXES THE DRYLINE
AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO OZONA LINE.
HOWEVER...SEVERAL OF THE HIRES CAMS HOLD THE DRYLINE FARTHER WEST
ALONG THE WESTERN BORDER OF THE CWA. GIVEN THE LACK OF A STRONG
MID LEVEL JET ROUNDING THE BASE OF THE TROUGH THROUGH EARLY
AFTERNOON /AND COLLABORATION WITH NEIGHBORING OFFICES/ I HAVE
OPTED FOR THE WESTERN PLACEMENT OF THE DRYLINE...KEEPING MOST OF
THE AREA WITHIN THE MOIST SECTOR.
THE 00Z GUIDANCE SUGGESTS TEMPS WILL BE 5-7 DEGREES COOLER THAN
YESTERDAY. HOWEVER...THE RAP WARMS SURFACE TEMPS UP TO NEAR 105
DEGREES AGAIN. WHILE THE INCREASE IN MID LEVEL CLOUDS AND
ADDITIONAL MOISTURE ON THE EAST SIDE OF THE DRYLINE WILL LIMIT
HEATING...I STILL DO NOT THINK WE WILL COOL OFF BY THAT MUCH. I
WENT WITH A COMPROMISE BETWEEN THE NAM AND RAP...WITH FORECAST
HIGHS GENERALLY 97 TO 101 DEGREES. INSTABILITY PARAMETERS ACROSS
THE AREA ARE IMPRESSIVE WITH MLCAPE VALUES OF 2000-3000 J/KG THIS
AFTERNOON. DEEP LAYER SHEAR LOOKS JUST SUFFICIENT FOR
SUPERCELLULAR ACTIVITY WITH AN ANTICIPATED 25-30 KTS OF 0-6KM
SHEAR. WITH THE INTENSE SURFACE HEATING...WE SHOULD SEE SEVERAL
UPDRAFTS PENETRATE THE CAP AND MATURE QUICKLY INTO POTENTIALLY
SEVERE THUNDERSTORMS. STEEP MID LEVEL LAPSE RATES WILL LEND TOWARD
A LARGE HAIL THREAT WITH ADIABATIC LAPSE RATES AND A DEEP...DRY
SUB CLOUD LAYER PROVIDING A WIND THREAT. THE EXTREMELY HIGH CLOUD
BASES WILL LIMIT THE TORNADO POTENTIAL THIS FAR SOUTH...BUT WILL
NOT RULE OUT THE THREAT ALTOGETHER. THE GREATEST POTENTIAL FOR
SEVERE WEATHER WILL BE ACROSS THE BIG COUNTRY WHERE THE CAP WILL
BE A BIT WEAKER BUT THE THREAT WILL EXIST AREAWIDE.
TONIGHT...ANY ONGOING CONVECTION WILL MOVE IN A GENERAL
NORTHEASTERLY DIRECTION AND MAY HANG ON FOR SEVERAL HOURS AFTER
SUNSET GIVEN THE ANTICIPATED INTERACTION OF THE LOW LEVEL
JET...DRYLINE AND INCREASING SYNOPTIC SCALE ASCENT. THE SEVERE
THREAT WILL CONTINUE AS WELL BUT WILL DECREASE ONCE WE LOSE
SURFACE HEATING. EXPECT OVERNIGHT TEMPERATURES TO FALL INTO THE
LOWER 70S FOR THE MOST PART WITH SOUTH WINDS OF 5 TO 15 MPH.
THANKS LUB FOR THE COORDINATION.
JOHNSON
LONG TERM...
NOT A LOT OF CHANGE NEXT WEEK. KEPT TEMPERATURES ABOVE GUIDANCE
ON SUNDAY...WITH SUBSIDENCE AS THE UPPER TROUGH MOVES EAST. A
LARGE...SLOW MOVING UPPER LOW IS EXPECTED TO DEVELOP OVER THE
CENTRAL AND UPPER MIDWEST EARLY NEXT WEEK. WEST CENTRAL TEXAS
WILL BE SOMEWHAT DRY SLOTTED BEING SOUTH SIDE OF THE UPPER LOW.
HOWEVER...THERE MAY STILL BE ENOUGH LOW LEVEL MOISTURE AROUND TO
GENERATE A FEW THUNDERSTORMS. THE BEST CHANCE OF STORMS IS ON
TUESDAY AS A WEAK COLD FRONT AND UPPER SHORTWAVE MOVE ACROSS THE
REGION. CAN NOT RULE OUT A FEW DRYLINE THUNDERSTORMS ON
MONDAY...AND ON THURSDAY INTO FRIDAY. WILL HOLD OFF MENTION OF
STORMS ON THESE DAYS HOWEVER ...AS RAINFALL POTENTIAL IS FAIRLY
LOW. I AM ALSO CONCERNED WITH UPPER RIDGING TAKING PLACE IN THE
SECOND HALF OF NEXT WEEK...WHICH WOULD ACT TO INHIBIT CONVECTION.
04
FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS ARE ANTICIPATED TODAY ACROSS MOST
OF WEST CENTRAL TEXAS AS TEMPERATURES WARM TO NEAR 100 DEGREES...
MINIMUM RELATIVE HUMIDITIES FALL TO 20-30 PERCENT AND SOUTH 20 FT
WINDS INCREASE TO AROUND 15-20 MPH. IN ADDITION...ISOLATED AFTERNOON
THUNDERSTORMS WILL BE POSSIBLE WHICH MAY RESULT IN OCCASIONAL CLOUD
TO GROUND LIGHTNING. RELATIVE HUMIDITIES WILL RECOVER TO 70-80
PERCENT OVERNIGHT BUT WILL TANK AGAIN ON SUNDAY AS TEMPERATURES SOAR
TO NEAR OR ABOVE 100 DEGREES YET AGAIN. ON SUNDAY AFTERNOON...THE
DRYLINE WILL MOVE A BIT FARTHER EAST...SPREADING SUB 20 PERCENT
RELATIVE HUMIDITIES AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO
OZONA LINE. SOUTHWEST 20 FT WINDS WILL BE AROUND 15 MPH...RESULTING
IN ELEVATED FIRE WEATHER CONDITIONS. EXPECT CONDITIONS TO IMPROVE
ONLY SLIGHTLY ON MONDAY BUT COOLER TEMPERATURES ARE ANTICIPATED BY
TUESDAY WHICH SHOULD ALLEVIATE FIRE WEATHER CONCERNS TEMPORARILY.
JOHNSON
CLIMATE...
THE MAX TEMP YESTERDAY IN SAN ANGELO OF 106 DEGREES SMASHED THE
PREVIOUS RECORD OF 100. LIKEWISE...ABILENE SET A NEW RECORD AS
WELL...TOPPING OUT AT 104 AND BESTING THE PREVIOUS MARK OF 101
DEGREES. WE MAY BE IN LINE FOR RECORD HIGH MINIMUM TEMPS THIS
MORNING. THE RECORDS OF 73 DEGREES AT BOTH ABILENE AND SAN ANGELO
MAY FALL AS 2 AM TEMPS ARE STILL IN THE 80S.
THIS AFTERNOON...MAX TEMPS ARE FORECAST TO WARM TO NEAR OR JUST
ABOVE 100 DEGREES. MAX TEMPS RECORDS ARE IN JEOPARDY AT BOTH
SITES. ABILENE HAS A RECORD HIGH TODAY OF 99 DEGREES WHILE SAN
ANGELO/S RECORD IS 102.
JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 100 71 97 69 94 / 20 20 5 10 10
SAN ANGELO 101 72 102 70 96 / 20 10 5 5 5
JUNCTION 97 70 99 71 91 / 10 10 10 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
645 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT MAY 18 2013
UPPER LEVEL RIDGING TAKING PLACE ACROSS THE UPPER MIDWEST TODAY AS
THE WESTERN CONUS TROUGH DEEPENS. PLENTY OF CONVECTION FIRING UP OFF
THE 850 MB LLJ IN CONJUNCTION WITH A PASSING SHORTWAVE ACROSS
CENTRAL MINNESOTA BACK INTO THE DAKOTAS. THIS ACTIVITY WILL MOSTLY
REMAIN NORTH/NORTHWEST OF THE FORECAST AREA...HOWEVER COULD CLIP
PORTIONS OF NORTH CENTRAL WISCONSIN BY MID TO LATE MORNING. LATEST
RUNS OF THE HRRR AND RAP SHOW CONVECTION WANING BUT POSSIBLY
IMPACTING TAYLOR AND CLARK COUNTIES IN WISCONSIN SO HAVE MAINTAINED
SHOWER/STORM CHANCES THERE. MOIST EASTERLY FLOW AND DECAYING
CIRRUS WILL KEEP SKIES MOSTLY CLOUDY TO OVERCAST THIS
MORNING...BUT AS THE MCS LIFTS NORTH...IT WILL PULL THE WARM FRONT
THROUGH THE AREA. PARTLY TO MOSTLY SUNNY SKIES WILL MOST LIKELY BE
SEEN ACROSS NORTHEAST IOWA WHERE THE FRONT IS ABLE TO CLEAR
THROUGH THE MOST.
DECENT INSTABILITY EXPECTED TODAY IN THE WARM SECTOR...AND MUCAPE
VALUES RANGE FROM 1000 TO 2000 J/KG IN A WEAKLY CAPPED ENVIRONMENT.
LACK OF SURFACE CONVERGENCE HOWEVER PRECLUDES HIGHER PRECIPITATION
CHANCES BUT MOST OF THE DETERMINISTIC AND PROBABILISTIC GUIDANCE
HINTS THAT CENTRAL WISCONSIN COULD SEE A STRAY SHOWER OR
THUNDERSTORM THIS AFTERNOON. HAVE MAINTAINED PRECIPITATION CHANCES
THERE. OTHERWISE...A WARM DAY ON TAP WITH LOWER TO MID 80S EXPECTED
SOUTH OF I-94.
RELATIVELY QUIET CONDITIONS TONIGHT AS CONVECTION IS EXPECTED TO
REMAIN WELL TO THE WEST AND NORTH. MILD NIGHT WITH SOUTHERLY
FLOW...AND OVERNIGHT LOWS IN THE UPPER 50S TO LOWER 60S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT MAY 18 2013
FOCUS IS ON SEVERE WEATHER CHANCES SUNDAY AND MONDAY AS ACTIVE
WEATHER PATTERN SETS UP ACROSS MUCH OF THE CENTRAL PLAINS.
UPPER LEVEL NEGATIVE TILTED SHORTWAVE TROUGH EJECTS INTO THE CENTRAL
PLAINS ON SUNDAY...MEANWHILE AT THE SURFACE A FEW WAVES OF LOW PRESSURE
SHOULD BE DEVELOPING ACROSS OKLAHOMA INTO NEBRASKA. THIS WILL PULL
NORTH AMPLE GULF OF MEXICO MOISTURE...WITH PWATS INCREASING FROM
AROUND 1 INCH...TO NEARLY 1.75 INCHES...OR 175 PERCENT OF NORMAL.
SURFACE DEWPOINTS WILL RISE INTO THE LOW TO MIDDLE 60S. THERE SHOULD
BE CONVECTION ACROSS WESTERN IOWA INTO SOUTHWEST MINNESOTA EARLY
SUNDAY MORNING...WHICH WILL BE FEEDING OFF THE 850 MB LLJ. THIS
SHOULD WEAKEN AS IT APPROACHES THE WESTERN FORECAST AREA BUT GOOD
CONSENSUS THAT SHOWERS AND THUNDERSTORMS WILL BE AROUND IN THE
MORNING HOURS. THEN...THE BIG QUESTION BECOMES HOW MUCH CLEARING
WE WOULD SEE TO AID IN DESTABILIZATION. ASSUMING WE CLEAR
OUT...0-3KM MUCAPE IS EXPECTED TO INCREASE TO 1500-2000
J/KG...HIGHEST TO THE SOUTH AND WEST. OVERALL THE SHEAR PROFILES
ARE LESS IMPRESSIVE...BUT STILL SHOW 0-3KM BULK SHEAR OF NEARLY 30
KTS. THE ATMOSPHERE DOES REMAIN UNCAPPED SO EXPECTING GOOD CHANCES
OF CONVECTIVE INITIATION WITH ORGANIZED STORMS IN THE FORM OF
SUPERCELLS OR POSSIBLY BOWING SEGMENTS. STRONG TO SEVERE STORMS
WOULD DEVELOP ACROSS WESTERN INTO CENTRAL IOWA...AND TRACK
EAST/NORTHEAST THROUGH THE EVENING HOURS. THE PRIMARY THREATS ARE
LARGE HAIL AND DAMAGING WINDS. THE ENVIRONMENT STILL SUPPORTS AN
ISOLATED TORNADO...HOWEVER DEPENDING WHERE A WARM FRONT LAYS IS
MORE UNCERTAIN. 18.00Z GFS HAS THIS BOUNDARY ACROSS CENTRAL
IOWA...BUT 18.00Z ECMWF/NAM HINT THIS COULD BE FURTHER SOUTH.
THE WHOLE SYSTEM EDGES EASTWARD MONDAY...WITH THE BOTH THE
SURFACE AND UPPER LEVEL LOW BECOMING STACKED NEAR SIOUX FALLS SD
BY 12Z MONDAY. PIECES OF ENERGY WILL BE ROTATING THROUGH SOUTHERN
BEND OF THIS TROUGH...LIFTING THROUGH THE AREA DURING THE DAY. THE
SYNOPTIC SETUP IS SLIGHTLY MORE FAVORABLE FOR SEVERE WEATHER FOR
PARTS OF THE AREA. THE SHEAR PROFILES ARE MORE IMPRESSIVE WITH
0-6KM BULK SHEAR VALUES 40 TO 50 KTS ACROSS EASTERN IOWA INTO
SOUTHERN WISCONSIN. THE MORE LIMITING FACTOR THIS DAY IS HOW MUCH
DESTABILIZATION WILL OCCUR. THERE COULD BE SCATTERED SHOWERS AND
PLENTY OF CLOUDS AROUND TO LIMIT INSTABILITY. IF WE CAN BREAK OUT
AND FULLY DESTABILIZE...THEN 0-3KM MUCAPE MAY REACH 1500 TO 2000
J/KG. THE ENVIRONMENT SHOULD SUPPORT DISCRETE STORM CELLS...WITH
THE THREATS AGAIN LARGE HAIL AND DAMAGING WINDS.
TUESDAY AND BEYOND...THE UPPER LOW REMAINS NEARLY STATIONARY ACROSS
THE UPPER MIDWEST. THIS GIVES PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS ACROSS THE ENTIRE AREA TUESDAY-THURSDAY. MODEL
CONSENSUS PAINTS 30 TO 60 PERCENT CHANCES WHICH IS APPROPRIATE AT
THIS TIME. FEEL THAT MUCH OF NEXT WEEK COULD BE UNSETTLED BUT SEE
LITTLE OPPORTUNITY TO PROVIDE MORE DETAILS IN WHAT PERIODS WOULD BE
MORE ACTIVE...SINCE TIMING PIECES OF ROTATING AROUND THE UPPER LOW
IS DIFFICULT THIS FAR OUT. THE BIGGER STORY WOULD BE THE HEIGHTENED
RISK FOR EXCESSIVE RAINFALL AND LOCALIZED FLOODING IF REPEATED
ROUNDS OF CONVECTION DO IMPACT THE AREA. BY MID-WEEK...SOILS WOULD
BECOME EVEN MORE SATURATED...AND FLASH GUIDANCE FURTHER REDUCED. SEE
HYDROLOGY SECTION BELOW FOR MORE DETAILS ON THAT RISK.
TEMPERATURE-WISE...WARMEST DAYS LOOK TO BE SUNDAY AND MONDAY BEFORE
A GRADUAL COOL DOWN TUESDAY...THEN TO BELOW NORMAL READINGS
WEDNESDAY THROUGH THURSDAY AS THE UPPER LOW DRIFTS OVERHEAD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 644 AM CDT SAT MAY 18 2013
WITH THE BEST FORCING REMAINING NORTH AND WEST OF THE FORECAST
AREA THROUGH THIS EVENING...KEPT THE TAF SITES DRY WITH CEILINGS
ABOVE 12K FEET. THE MESO MODELS ARE IN GOOD AGREEMENT THAT A SHORT
WAVE TROUGH WILL MOVE NORTHEAST THROUGH THE AREA. THIS WILL BRING
SHOWERS AND THUNDERSTORMS TO NORTHEAST IOWA AND SOUTHEAST
MINNESOTA AFTER 19.09Z. DESPITE THIS PRECIPITATION...SOUNDINGS
SUGGEST THAT THE CEILINGS WILL REMAIN VFR. WHILE THERE MAY BE
SOME BRIEF VISIBILITIES IN THE IFR/MVFR RANGE...TIMING IS VERY
UNCERTAIN...SO LEFT THEM VFR.
&&
.HYDROLOGY...SUNDAY AND INTO NEXT WEEK
ISSUED AT 400 AM CDT SAT MAY 18 2013
HEAVY RAINFALL /2 TO 2.5 INCHES/ FELL FRIDAY ACROSS PORTIONS OF
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...AND COMBINED WITH A RECORD
WET METEOROLOGICAL SPRING...RESULTS IN AN INCREASED RISK FOR
LOCALIZED FLASH FLOODING AS WE HEAD INTO THE LATTER PART OF THE
WEEKEND AND MUCH OF NEXT WEEK. PERIODS OF SHOWERS AND THUNDERSTORMS
LOOK TO IMPACT MUCH OF SOUTHEAST MINNESOTA AND NORTHEAST BEGINNING
SUNDAY AFTERNOON. AN ADDITIONAL 1 TO 3 INCHES IS POSSIBLE...AND IF
THIS FALLS IN A SHORT PERIOD...LOCALIZED FLASH FLOODING WOULD OCCUR.
THE 1 AND 3 HOUR FLASH GUIDANCE REMAINS WELL BELOW NORMAL...AND IS
GENERALLY LESS THAN 1 AND 2 INCHES...RESPECTIVELY. WPC CONTINUES THE
SLIGHT RISK OF EXCESSIVE RAINFALL AND FLASH FLOODING EARLY NEXT WEEK
ACROSS MUCH OF CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. A FLASH
FLOOD WATCH MAY BE NECESSARY FOR PORTIONS OF THE AREA.
STREAMS...CREEKS...AND RIVERS HAVE RESPONDED TO THE RECENT
RAINFALL...MOSTLY WITHIN BANK RISES. HOWEVER...REPEATED ROUNDS OF
HEAVY RAIN COULD PUSH SOME OF THE MORE FLASHY BASINS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA TO NEAR FLOOD STAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...BOYNE
HYDROLOGY...ZT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
642 AM CDT SAT MAY 18 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
MORE AMPLIFIED PATTERN THIS PERIOD AS WESTERN TROF DIGS SOUTHEAST
AND CUTS OFF OVER THE CENTRAL PLAINS. BUILDING HEIGHTS OVER STATE
TODAY AS RIDGE MOVES EAST ACROSS STATE THIS PERIOD WILL LEAD TO
LESSENING CHANCE OF PCPN TODAY. LOCAL RADARS CURRENTLY SHOWING
ISOLD TO SCATTERED SHOWERS OVER NORTHERN WI. TO THE WEST...AREA OF
THUNDERSTORMS MOVING THROUGH MN AND FAR WESTERN WI NORTH OF
STATIONARY/WARM FRONT AND AHEAD OF VORT EJECTING OUT OF UPPER
TROF. MOST TEMPERATURES REMAIN IN THE LOWER 50S AT THIS TIME GIVEN
CLOUDS AND EAST FLOW.
AGAIN...FOCUS OF FORECAST ON PCPN CHANCES AND TEMPS. SHOWERS OVER
NORTHERN WI NORTH OF 850H BAROCLINC ZONE...AREA OF SIG WAA. HAVE
TRENDED TOWARDS A BLEND OF NAM AND EC...AND MESO HRRR MODELS. ALL
SUGGEST PCPN TO SHIFT NORTH THIS MORNING...LEAVING MUCH OF CWA DRY
THIS AFTERNOON. HAVE KEPT A BUFFER OF CHANCE POPS OVER WEST.
RIDGE AXIS PASSES OVERHEAD TONIGHT. HAVE STAYED WITH DRY FORECAST.
ON SUNDAY...PCPN CHANCES INCREASE THROUGH THE DAY AS RIDGE TO BE
EAST OF STATE AND DYNAMICS WITH UPPER TROF COME IN TO PLAY.
STRENGTHENING LLVL FLOW (30 TO 35 KTS AT 850) STRAIGHT OUT OF GULF
TO BRING PW VALUES TO 1.5 INCHES OR GREATER. INSTABILITY INCREASES
WITH MID LEVEL LAPSE RATES AT 7. EC SUGGESTS CAPE VALUES AROUND
1K...NAM SHOWING NORMAL HIGH BIAS. THOUGH MODEL SOUNDINGS SHOW
STRONG CIN OVER EAST THROUGH DAY. HAVE STAYED DRY EAST THROUGH THE AFTN.
TEMPS TO BE A HEADACHE AGAIN TODAY WITH CLOUDS...ONGOING PCPN AND
EAST FLOW OFF LAKE. DID NOT STRAY TOO FAR FROM PREVIOUS FORECAST.
WENT A BIT HIGHER ON CLOUDS GIVEN PLENTY OF CIRRUS FLOWING THIS
WAY FROM UPSTREAM CONVECTION. STAYED WITH TEMPS HITTING 80 ON SUN
AS BEST PERFORMING GUIDANCE SUGGESTS...THOUGH UNCERTAINTY SIG
GIVEN POSSIBLE CONVECTION.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
PRECIPITATION CHANCES FOR MUCH OF THE UPCOMING WEEK ARE THE MAIN
CONCERNS DURING THIS PART OF THE FORECAST.
THUNDERSTORMS LOOK LIKE A PRETTY GOOD BET ACROSS THE AREA ON
SUNDAY NIGHT WITH SHORT WAVE ENERGY PASSING THROUGH...AN
APPROACHING SURFACE LOW AND A FRONTAL BOUNDARY MOVING NORTHEAST
ACROSS THE AREA. THOUGH EASTERLY COMPONENT OF SURFACE FLOW OFF
LAKE MICHIGAN MAY LESSEN THE CHANCES FOR STORMS IN THE EAST.
HAVE LIKELY POPS FOR MONDAY AND MONDAY NIGHT. SPC DAY 3 OUTLOOK
HAD CENTRAL AND EAST CENTRAL WISCONSIN IN SLIGHT RISK AS A SURFACE
LOW APPROACHES AND A CLOSED 500MB CYCLONE MAKES ITS WAY TOWARD THE
STATE. STILL QUITE A BIT OF UNCERTAINTY REGARDING THIS SEVERE
THREAT.
THE SURFACE LOW SHOULD MAKE ITS WAY INTO WESTERN WISCONSIN ON
TUESDAY AS BOTH THE SURFACE AND UPPER LEVEL SYSTEMS MAKE THEIR WAY
ACROSS THE WESTERN GREAT LAKES REGION. THUNDER CHANCES SHOULD
DIMINISH AS THE SYSTEMS PASS EAST OF THE FORECAST AREA AND THE
CHANCE OF SHOWERS SHOULD FINALLY COME TO AN END BY THE END OF THE
WORK WEEK.
TEMPERATURES AT THE START OF THE PERIOD ARE EXPECTED TO BE ABOVE
NORMAL BUT COOLER TEMPERATURES ARE FORECAST FOR THE REST OF THE
WEEK...WITH HIGHS MAINLY IN THE 60S EACH DAY.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 632 AM CDT SAT MAY 18 2013
SOME UNCERTAINTY WESTERN SITES WITH PATH/LONGEVITY OF STORMS
ONGOING OVER MN. STORMS TRENDING TO TURN RIGHT THIS
MORNING...THOUGH WEAKEN AS THEY MOVE EAST. BASIC TREND OF THE FORECAST
IS DRY AS RIDGE BUILDS IN. LIGHT WINDS AND AVAILABLE MOISTURE...TO
LEAD TO MVFR FOG OVERNIGHT. INCREASING CHANCE OF STORMS LATE SUN
INTO MON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......TE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1133 AM MDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 418 AM MDT SAT MAY 18 2013
FIRE WEATHER CONDITIONS ARE THE MAIN CONCERN FOR TODAY. AN UPR TROF
WL BE OVR THE GREAT BASIN TODAY AND WL MOVE INTO WRN CO BY EVENING
AND THEN WL BE MOVING ACRS THE STATE OVERNIGHT. AHEAD OF THE UPR
TROF...W TO SW WINDS SFC WINDS WL INCREASE TODAY WITH MOST AREAS
BEING BREEZY TO WINDY. DEW POINT FORECAST IS A BIT DIFFICULT...BUT
WL LEAN TOWARD THE HRRR FORECAST WHICH IS DRIER THAN THE NAM12 AND
THE RAP13. HIGH TEMPS TODAY SHOULD BE A LITTLE COOLER THAN
YESTERDAY...BUT STILL ABOVE NORMAL OVER THE ERN AREAS AND AROUND
NORMAL FOR THE SAN LUIS VALLEY. THE RED FLAG WARNING FOR BACA AND
EASTERN LAS ANIMAS COUNTIES STILL LOOKS GOOD...BUT IT NOW LOOKS LIKE
MIN RH VALUES AND WINDS MAY MEET RED FLAG CRITERIA FOR A LONG
ENOUGH PERIOD OVER MUCH OF THE SAN LUIS VALLEY AND OVER SRN EL PASO
COUNTY WHERE THE FUELS ARE DRY...AND THUS WL ADD THESE AREAS TO THE
RED FLAG WARNING.
BY LATE MORNING THERE WL PROBABLY BE SOME ISOLD SHOWERS/TSTMS OVR
THE MTS...WITH BEST CHANCES BEING ALONG THE CONTDVD. PCPN CHANCES
SHOULD THEN INCREASE OVR THE MTS AND HIGH VALLEYS IN THE AFTERNOON.
THE DRY LINE IS EXPECTED TO PUSH EAST INTO KS WITH THE SERN PLAINS
REMAINING DRY. THE NAM12 HAS SOME PCPN DEVELOPING OVR THE FAR SERN
PLAINS THIS AFTERNOON...BUT BELIEVE THAT THE DEW POINTS IN THE NAM
ARE TOO HIGH. HOWEVER THERE IS A CHANCE THAT WE COULD SEE SOME TSTM
DEVELOPMENT OVR ERN PORTIONS OF KIOWA COUNTY WHERE THE HIGHEST DEW
POINTS WL LIKELY BE...SO WL KEEP SOME ISOLD POPS IN THAT AREA. SPC
HAS THE FAR ERN PORTIONS OF KIOWA COUNTY IN THE SLIGHT RISK AREA FOR
TODAY. CHANCES FOR SHOWERS/TSTMS CONTINUE OVR AND NR THE HIGH
COUNTRY THIS EVENING...WITH LITTLE CHANCE FOR PCPN OVR THE SERN
PLAINS. SFC WINDS THIS EVENING WL BE WESTERLY AND BREEZY MOST AREAS
AND THEN WL BECOME MORE NWRLY BY LATE NIGHT. MOST AREAS SHOULD BE
DRY BY LATE NIGHT...BUT THE CENTRAL MTS WL PROBABLY CONTINUE TO SEE
A FEW SHOWERS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 418 AM MDT SAT MAY 18 2013
SUNDAY-MONDAY NIGHT...MODELS CONTINUE TO INDICATE A COOL AND
GENERALLY UNSETTLED WEATHER PATTERN ACROSS THE AREA WITH A BROAD
UPPER TROUGH IN PLACE ACROSS THE INTERMOUNTAIN WEST THROUGH THE HIGH
PLAINS...ALONG WITH SEVERAL EMBEDDED SHORT WAVES TRANSLATING ACROSS
THE ROCKIES THROUGH THE PERIOD. FIRST WAVE ACROSS SOUTH CENTRAL
COLORADO EARLY SUNDAY MORNING CONTINUES TO TRANSLATE OUT ACROSS THE
SOUTHEAST PLAINS AND INTO WESTERN KANSAS SUNDAY AFTERNOON KEEPS THE
CHANCE FOR ISOLATED TO SCATTERED SHOWERS ACROSS THE AREA SUNDAY
MORNING AND AFTERNOON. MODELS CONTINUE TO INDICATE MAINLY HIGH BASED
STORMS WITH CONTINUED INVERTED V PROFILES...SAVE THE FAR SE PLAINS
WHERE LOW LEVEL MOISTURE FILTERS BACK INTO THE AREA FROM WESTERN
KANSAS WITH NORTHERLY FLOW BEHIND A BACKDOOR COLD FRONT MOVING
ACROSS EASTERN COLORADO.
NEXT SHORT WAVE DIGGING INTO NORTHWESTERN COLORADO LATE SUNDAY NIGHT
CONTINUES TO SLOWLY LIFT OUT ACROSS THE STATE THROUGH MONDAY NIGHT.
THIS PERIOD STILL LOOKS TO BRING THE BEST CHANCES OF WETTING
RAINFALL ALONG WITH ANOTHER LATE SEASON SHOT OF HIGHER ELEVATION
SNOWFALL...AS H7 TEMPS PROGGED TO DROP TO BETWEEN 0C AND 4C. WITH
THAT SAID...MONDAY STILL LOOKS TO BE THE COOLEST DAY OF THE UPCOMING
WEEK WITH POTENTIAL FOR SUB FREEZING OVERNIGHT LOWS ACROSS THE HIGH
MT VALLEYS SUNDAY NIGHT AND MONDAY NIGHT.
TUESDAY-WEDNESDAY...SLOW WARMING TREND ON TAP WITH BRISK NORTHWEST
FLOW ALOFT ACROSS THE AREA TUESDAY MODERATING THROUGH WEDNESDAY AS
UPPER LEVEL RIDGING BUILDS INTO WESTERN COLORADO. MODELS CONTINUE TO
INDICATE SHOWERS ACROSS THE HIGHER TERRAIN...MOST NUMEROUS ACROSS
THE EASTERN MTS TUESDAY AFTERNOON WITH DEVELOPING LOW LEVEL UPSLOPE
FLOW. MORE ISOLATED HIGH BASED STORMS REMAIN POSSIBLE WEDNESDAY
AFTERNOON.
THURSDAY-FRIDAY...UPPER RIDGE AMPLIFIES INTO THE HIGH PLAINS AS A
BROAD UPPER TROUGH CARVES OUT ACROSS THE PAC NORTHWEST. WARMING
ALOFT WILL ALLOW TEMPS TO WARM BACK TO AT AND SLIGHTLY ABOVE
SEASONAL AVERAGES INTO THE UPCOMING WEEKEND. ISOLATED HIGH BASED
STORMS REMAIN POSSIBLE OVER THE HIGHER TERRAIN WITH INCREASING
SOUTHERLY FLOW LEADING TO THE POTENTIAL FOR LATE AFTERNOON AND
EARLY EVENING THUNDERSTORMS ACROSS THE EASTERN PLAINS...AS LOW
LEVEL MOISTURE STREAMS BACK INTO EASTERN COLORADO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1130 AM MDT SAT MAY 18 2013
VFR CONDITIONS ARE EXPECTED DURING THE NEXT 24H AT ALL 3 TAF
SITES...KPUB...KALS AND KCOS.
GUSTY WINDS FROM THE WEST-SOUTHWEST (15G25KT) WILL BE POSSIBLE
THROUGH MID AFTERNOON. WINDS WILL SHIFT TO MORE NORTHWESTERLY BY
LATER IN THE AFTERNOON.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ224-227-233-
237.
&&
$$
SHORT TERM...28
LONG TERM...MW
AVIATION...HODANISH
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
535 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL GRADUALLY MOVE INTO THE AREA SUNDAY
INTO TUESDAY...THEN WILL STALL AND DISSIPATE AS ATLANTIC HIGH PRESSURE
BECOMES THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK. A COLD FRONT
WILL APPROACH THE REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
LATE THIS AFTERNOON...CONVECTION HAS DRIFTED SLOWLY TO THE EAST
OVER THE PAST HOUR OR TWO AND HAS NOTICEABLY WEAKENED. MUCH OF THIS
IS DUE TO DWINDLING MLCAPE AND THE HIGH CLOUDS SPAWNED BY THESE
THUNDERSTORMS WILL CONTINUE TO INHIBIT DESTABILIZATION DOWNSTREAM.
THE UPDATED POPS FAVOR THE 18/19Z HRRR WHICH SHOWS THE CURRENT
CONVECTION DISSIPATING IN PLACE. ALSO UPDATED HOURLY TEMPS WHICH
SHOW SIGNIFICANT SPATIAL VARIABILITY THANKS TO RAIN COOLED AIR AND
THUNDERSTORM OUTFLOW.
TONIGHT...WITH THE LOSS OF AFTERNOON HEATING ANY REMAINING
SHOWER/STORM ACTIVITY WILL DECREASE THIS EVENING. THROUGH THE
OVERNIGHT...THE BAGGY UPPER TROUGH ALOFT WILL CONTINUE TO MEANDER
AROUND JUST TO THE NORTH AND NORTHWEST OF THE FORECAST AREA. A
PERUSAL OF MODEL SOUNDINGS SHOWS CONTINUED MOISTENING AND THE
PRESENCE OF ELEVATED INSTABILITY THROUGH DAYBREAK. IN
FACT...SHOWALTERS GO TO AROUND -1 OR -2. MANY OF THE SUITE OF
MODELS DEPICTS SHOWER/STORM COVERAGE INCREASING LATE ACROSS MUCH
OF THE AREA AND STREAMING IN FROM OFFSHORE. POPS SHOW A DECREASING
TREND THROUGH THE EVENING AND THEN RAMP BACK UP TO CHANCE TOWARDS
SUNRISE. PLENTIFUL CLOUD COVER AND WARM SOUTHERLY FLOW WILL KEEP
LOWS IN THE MID/UPPER 60S IN MOST AREAS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
THE UPSTREAM SHORTWAVE TROUGH WILL SETTLE INTO THE REGION SUNDAY
THROUGH MONDAY...THEN WILL STALL AND SLOWLY UNRAVEL/WEAKEN OVER THE
REGION BY THE END OF THE FORECAST PERIOD. THE OVERALL REGIME WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS...SIGNIFICANT
CLOUD COVER AND TEMPERATURES NOT EXCEEDING THE LOWER TO MID 80S AT
MOST LOCALES. OF GREATEST INTEREST...LOCALLY HEAVY RAINFALL IS
POSSIBLE GIVEN PWATS INCREASING TO BETWEEN 1.5 AND 1.8 INCHES/
1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL FOR MID-MAY AND MULTICELL
CONVECTION WITHIN A RELATIVELY WEAK STEERING FLOW REGIME/MODULATED
BY MESOSCALE BOUNDARIES.
GIVEN THE COMPLEX CONVECTIVE SCENARIO...FORECAST DETAILS WILL REMAIN
VERY DIFFICULT TO PIN DOWN BEYOND THE NEAR TERM FORECAST PERIOD. IN
GENERAL...PRECIPITATION COVERAGE SHOULD GENERALLY INCREASE PER
DIURNAL WARMING/DESTABILIZATION EACH AFTERNOON/EVENING. THE GREATEST
POTENTIAL COVERAGE WILL SUNDAY AND MONDAY PM...THEN DIURNAL
PRECIPITATION COVERAGE SHOULD BE RELATIVELY MORE SPARSE TUESDAY PM
DUE TO BUILDING HEIGHTS ALOFT AND AN ASSOCIATED WEAKENING OF THE
MID/UPPER VORTICITY MAXIMUM. HOWEVER...THE DEGREE OF DIURNAL
WARMING/DESTABILIZATION WILL DEPEND ON CLOUD COVER/ANTECEDENT
PRECIPITATION. INDEED...UPSTREAM/CLOSER TO THE UPPER LOW SATURDAY
AFTERNOON EARLIER PRECIPITATION AND LINGERING CLOUD COVER HELD
TEMPERATURES IN THE 70S AND HAD LIMITED COVERAGE/INTENSITY OF
PRECIPITATION...AND THIS SCENARIO CANNOT BE RULED OUT IN OUR AREA
SUNDAY/MONDAY.
OTHERWISE...CANNOT RULE OUT SHOWERS/THUNDERSTORMS AT ANY TIME
THROUGH THE PERIOD. FOR EXAMPLE...18/12Z GUIDANCE GENERALLY
INDICATES AN INCREASE IN DEEP LAYER MOISTURE AND AN ASSOCIATED
INCREASE IN SHOWER COVERAGE OVERNIGHT SUNDAY NIGHT/EARLY
MONDAY...ESPECIALLY ACROSS NORTHERN/EASTERN COUNTIES. WHILE
CONFIDENCE IN THIS SCENARIO IS NOT NECESSARILY HIGH...MODEL TRENDS
JUSTIFY AN INCREASE IN POPS OVERNIGHT SUNDAY NIGHT INTO EARLY
MONDAY. FURTHER...OTHERWISE...HIGHEST POPS ARE CAPPED IN THE HIGH
CHANCE/LOW LIKELY CATEGORY INLAND DURING THE SUNDAY/MONDAY PM
PERIOD...BUT SIGNIFICANT REFINEMENTS WILL BE REQUIRED WITHIN
SUBSEQUENT FORECAST PACKAGES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
AT KSAV...THE AIRFIELD DID RECEIVE A GLANCING BLOW FROM A
WEAKENING THUNDERSTORM WHICH BRIEFLY CAUSED VISIBILITY REDUCTIONS.
BASED ON CURRENT RADAR IT APPEARS THAT THUNDERSTORMS WILL REMAIN
IN THE VICINITY OF THE AIRFIELD THROUGH ABOUT 23Z BEFORE
COMPLETELY DISSIPATING. THEN OVERNIGHT...MODEL GUIDANCE SHOWS THE
POTENTIAL FOR DEVELOPING MVFR CEILINGS LATE WHICH THEN CONTINUES
THROUGH MUCH OF THE MORNING. STILL NOT CONFIDENT ENOUGH TO
ADVERTISE PREVAILING MVFR CONDITIONS SO I HAVE JUST ADDED A
MENTION OF SCATTERED MVFR LEVEL CLOUDS.
AT KCHS...AFTERNOON THUNDERSTORMS ARE EXPECTED TO REMAIN WEST OF
THE AREA. THE MAIN THING TO KEEP AN EYE ON IS THE OVERNIGHT PERIOD
WHEN MUCH OF THE MODEL GUIDANCE SHOWS ISOLATED/SCATTERED SHOWERS
DEVELOPING ALONG THE SC COASTLINE WITHIN SOME WEAK CONVERGENCE. I
HAVE INTRODUCED VCSH STARTING AT 09Z AND WITH ANY SHOWERS THAT DO
DEVELOP MVFR CEILINGS ARE POSSIBLE.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. DIRECT/TRANSIENT IMPACTS
INCLUDING FLIGHT RESTRICTIONS FROM ISOLATED TO SCATTERED
SHOWERS/THUNDERSTORMS WILL LIKELY OCCUR THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KTS
WITH SEAS 2-4 FT.
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS RANGING FROM 10 TO 15 KNOTS...WITH LOCALLY/BRIEFLY STRONGER
ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE DIURNAL SEA BREEZE
CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4 FEET MUCH OF THE
TIME...ALTHOUGH SEAS AS HIGH AS 5-6 FT COULD BEGIN TO IMPINGE UPON
WATERS BEYOND 20 NM BY MID TO LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...BSH
MARINE...BSH/SPR
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
138 PM EDT SAT MAY 18 2013
.PREV DISCUSSION... /ISSUED 438 AM EDT SAT MAY 18 2013/
SHORT TERM /TODAY THROUGH SUNDAY/...
COMPLEX AND DIFFICULT FORECAST THE NEXT 24 TO 36 HOURS. SLOW MOVING
AND WEAK UPPER LEVEL LOW NOTED IN WATER VAPOR OVER CENTRAL TN
RESPONSIBLE FOR SHOWERS AND A FEW STORMS MOVING INTO WESTERN GA NOW
THROUGH SAT AM. MODELS CONTINUE TO KEEP THE REGION IN A GENERAL
NORTHWEST FLOW PATTERN THROUGH SUNDAY WITH WEAK DISTURBANCES MOVING
SOUTHEAST ON THE SOUTHWEST SIDE OF THE WEAK UPPER LOW. ALL OF THE
MODELS AGREE ON CHANCE TO LIKELY POPS FOR A PORTION OF THE AREA BUT
DISAGREE ON EXACT LOCATION AND TIMING...MOST LIKELY DUE TO
DIFFICULTIES RESOLVING THESE FEATURES. FOR TODAY...BIG QUESTION
WITH THIS ONGOING ACTIVITY IS HOW MUCH CLOUD DEBRIS WILL REMAIN AND
HINDER OR DELAY ANY DAYTIME HEATING ACROSS GA AND THE ONSET OF
THUNDERSTORM DEVELOPMENT. HRRR AND HIGH RES WRF CONTINUE TO SHOW
SHOWERS THROUGH MORNING WITH MORE SCATTERED CONVECTION DEVELOPING
THIS AFTERNOON. AS A RESULT...HAVE OPTED TO MAINTAIN SOME
CONSISTENCY WITH THE PREVIOUS FORECAST WHICH SHOWS HIGHEST POPS
ACROSS NORTHERN GA THROUGH SAT AND LESSER POPS ACROSS THE SOUTHERN
TIER. WILL HAVE TO WATCH THE SOUTHERN TIER OF COUNTIES AS
DIFFERENTIAL HEATING MAY HAVE A BIGGER THAN CURRENT MODELS
FORECASTING GIVEN THE LOCATION OF THE CURRENT ACTIVITY.
WILL HAVE TO WATCH AREA SAT NIGHT INTO SUNDAY AS SEVERAL MODELS ARE
HINTING AT SOME TYPE OF MCS DEVELOPMENT IN NORTHERN AL AND TN.
GIVEN THE NORTHWEST FLOW AND THESE DISTURBANCES...CANT RULE IT OUT.
GFS INSTABILITY FORECAST FOR SUNDAY IS IMPRESSIVE WITH 500 TO 700 MB
LAPSE RATES OVER 8 DEG C/KM FOR NORTHWEST GA. ALONG WITH CAPE
VALUES 2000 TO AS MUCH AS 4000 J/KG ... THERE WILL BE SOME SEVERE
POTENTIAL...HOWEVER SHEAR VALUES ARE LESS THAN MARGINAL SO
CONFIDENCE ON A MORE WIDESPREAD SEVERE EVENT IS LESS. MAIN IMPACTS
WILL BE DAMAGING WINDS AND HAIL. TIMING OF STORMS ON SUNDAY IS A
CRAP SHOOT AT THIS POINT AND MODEL TIMING IS ALL OVER THE PLACE
GIVEN THE POTENTIAL MCS DEVELOPMENT EARLY ON SUN. NEEDLESS TO
SAY...WILL NEED TO WATCH THE FORECAST CLOSELY THROUGH THE WEEKEND AS
IT COULD CHANGE SIGNIFICANTLY FOR BETTER OR WORSE.
HIGH PW VALUES AND THE SLOW MOVING NATURE OF THESE DISTURBANCES HAVE
THE POTENTIAL TO PRODUCE SOME ISOLATED FLASH FLOODING...PARTICULARLY
ACROSS NORTH GA BOTH SAT AND SUN. WILL NEED TO ALSO MONITOR THIS AS
WELL AS THE SEVERE THREAT.
30
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HAVE ADJUSTED POPS UPWARD FOR SUNDAY NIGHT ACROSS THE CWFA. MODELS
ARE SHOWING SIGNS OF AN MCS DEVELOPING IN THE NW FLOW AND AFFECTING
THE CWFA. STRONG SURFACE INSTABILITY AND VERY STEEP LAPSE RATES WILL
HELP SUSTAIN CONVECTION AND CONTINUE THE POSSIBILITY OF SEVERE
STORMS AT LEAST THROUGH MIDNIGHT.
FOR MONDAY...A 500MB TROUGH/SHEAR AXIS SETS UP RIGHT ALONG THE SE
COAST. THIS FEATURE SHOULD SERVE TO FOCUS ANY CONVECTIVE ACTIVITY
FOR MONDAY AND MONDAY EVENING. DO THINK SHRA/TSRA WILL BE MORE
DIURNAL IN NATURE. KEPT THE TREND OF HIGHEST POPS IN THE EAST...WITH
ONLY ISOLATED ACTIVITY TO THE WEST.
WEAK SHEAR AXIS/500MB TROUGH MOVES OFF THE COAST ON TUESDAY WITH
RIDGING BUILDING ALOFT ACROSS THE CWFA. ANY CONVECTION SHOULD BE
ISOLATED IN NATURE...SURFACE INSTABILITY WILL BE PRESENT BUT NO
DISCERNIBLE SURFACE MECHANISM TO FOCUS PRECIP IS NOTED. PRECIP
SHOULD BE DIURNAL.
UNCERTAINTY BEGINS TO CREEP INTO THE FORECAST BY WEDNESDAY. EARLIER
MODEL RUNS PROGGED A COLD FRONT TO MOVE THROUGH THE CWFA DURING THE
LATTER HALF OF THE WEEK. THE ECMWF NOW KEEPS THE FRONT TO THE
NORTH...WHILE THE GFS DOES MOVE THE BOUNDARY THROUGH SLOWLY FRIDAY
THROUGH SATURDAY. HAVE OPTED TO GO PERSISTENCE FOR THIS PERIOD DUE
TO LOW CONFIDENCE.
NLISTEMAA
&&
.AVIATION...
18Z UPDATE...
MVFR CIGS ACROSS ATL/AHN AREAS SHOULD CONTINUE TO LIFT WITH AREAS
GOING VFR BY 21Z AND REMAINING VFR UNTIL LATE TONIGHT. SCATTERED
CONVECTION WILL BE POSSIBLE THROUGH THE AFTERNOON. ANY CONVECTION
THAT DOES DEVELOP SHOULD DIMINISH TO SHOWERS LATE THIS EVENING. A
SECOND SHORT WAVE WILL MOVE INTO NORTH GA LATE TONIGHT AND SPREAD
INTO CENTRAL GA SUNDAY BRINGING AN INCREASING CHANCE OF CONVECTION
THROUGH THE DAY. WINDS WILL REMAIN SOUTHWEST LESS THAN 10KTS THROUGH
THE FORECAST.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS ON CIGS/VSBYS.
LOW TO MEDIUM ON TIMING OF CONVECTION.
17
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 80 63 79 65 / 60 60 60 60
ATLANTA 78 65 79 66 / 70 70 60 60
BLAIRSVILLE 73 60 76 60 / 70 70 70 70
CARTERSVILLE 78 63 79 65 / 70 70 60 50
COLUMBUS 83 67 85 67 / 90 50 40 50
GAINESVILLE 76 63 76 63 / 70 70 70 60
MACON 85 64 84 66 / 50 50 60 60
ROME 79 63 81 65 / 70 70 60 40
PEACHTREE CITY 79 64 79 65 / 60 60 60 60
VIDALIA 88 69 87 68 / 40 40 60 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
343 PM CDT SAT MAY 18 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 330 PM CDT SAT MAY 18 2013
MAIN CONCERNS TONIGHT WILL BE EXTENT OF CONVECTION ACROSS THE
FORECAST AREA LATE NIGHT AND INTO EARLY MORNING. MODELS SIMILAR IN
TIMING BUT VERY LITTLE AGREEMENT IN AREAL COVERAGE/PLACEMENT OF
RAINFALL OVERNIGHT SO CONFIDENCE LOW AT THIS TIME. SYNOPTIC SETUP
SHOWS APPROACHING H700 SHORTWAVE OVER PANHANDLE AREA OF TEXAS/OK
NOW AND SIMPLE TIME OF ARRIVAL TOOL SHOWS AT CURRENT SPEED WILL
ARRIVE INTO SW COUNTIES AFT 07Z AND INTO CENTRAL IOWA BY ABOUT
10Z...FAVORED TIME FOR NOCTURNAL CONVECTION. THIS CORRELATES
PRETTY WELL WITH INCREASING WIND FIELDS FROM THE GFS OVERNIGHT
WITH H850 40KT JET ENTERING AREA AND SUFFICIENT SPEED SHEAR FROM
H700/H500 OF 40-60KTS RESPECTIVELY FROM 08-12Z. SFC BOUNDARY LOOKS
TO MAKE IT AS FAR NORTH AS IA/MO BORDER BY 12Z AS WELL. MOISTURE
IS QUITE HIGH FOR THIS EVENT WITH PWATS BY 12Z APPROACHING +90-95%
LEVEL OF CLIMATOLOGICAL MAX AND NEAR 2 STANDARD DEVIATIONS FROM
NORMAL. WARM CLOUD DEPTHS LOOK FAIRLY IMPRESSIVE WITH 10-11KFT
EXPECTED LATE TONIGHT AND A GOOD SHARE OF SUNDAY AS WELL. WITH
EXPECTED SHORT WAVE AND FORECAST CONDITIONS...HAVE SOME CONCERNS
ABOUT LOCALLY HEAVY RAINFALL AND POTENTIAL FOR ISOLATED FLASH
FLOODING OVER THE WEST/SOUTHWEST AREAS SHOULD MCS HOLD TOGETHER AS
IT TRACKS NORTHEAST. CURRENT 3 HR GRIDDED FLASH FLOOD GUIDANCE OF
+2-3 INCHES REMAINS PRETTY HIGH OVER MUCH OF SOUTHERN 2 TIER
COUNTIES...BUT WEST OF I35 AND AREAS NORTH OF THERE HAVE LOWER
VALUES OF 1.75 TO 2 INCHES IN GENERAL. WITH HIGH PWATS AND
SIGNIFICANT WARM CLOUD DEPTHS COMBINED WITH SHORT WAVE WE CLOUD
SEE ISOLATED RAINFALL AMOUNTS OF 1 TO 2+ INCHES OVER THE SOUTHWEST
TO CENTRAL COUNTIES BY 12Z...WITHIN TRACK OF MCS. THE CHALLENGE
REMAINS HOWEVER...IN THAT THE 4 KM WRF AND HRRR WILL NEED TO WATCH
THIS THROUGH EVENING TO SEE HOW SITUATION EVOLVES. LOWS OVERNIGHT
WILL BE QUITE MILD AGAIN WITH INCREASING MOISTURE PUTTING A CAP ON
MINS IN THE LOWER TO MID 60S. SOME CONCERN REMAINS ABOUT POTENTIAL
FOR SEVERE OVERNIGHT...BUT IF ANY OCCURS WILL BE MAINLY FOR LARGE
HAIL OVER THE WEST.
.LONG TERM.../SUNDAY THROUGH SATURDAY/...
ISSUED AT 330 PM CDT SAT MAY 18 2013
MAIN FORECAST CONCERN REMAINS FOCUSED ON ACTIVE WEATHER PATTERN
DEVELOPING OVER THE NEXT SEVERAL DAYS. MODELS IN GOOD AGREEMENT
THROUGH EARLY IN THE WEEK WITH CUTOFF LOW LINGERING THROUGH
THURSDAY. LEANED A BLEND OF THE NAM12 AND ARW-WRF FOR TIMING AND
TRENDS TOMORROW INTO TOMORROW NIGHT...THEN A GFS/ECMWF THROUGH
MIDWEEK.
.SUNDAY INTO MONDAY...STRONG 500MB TROUGH DIGS INTO THE CENTRAL
PLAINS TONIGHT AND SLOWLY MAKE ITS WAS INTO THE MIDWEST BY TOMORROW.
FIRST SHORTWAVE THAT MAY SPAWN THUNDERSTORMS OVERNIGHT TONIGHT
LINGERS INTO NORTHERN IOWA THROUGH SUNDAY MORNING AND DIMINISH AS
THE LLJ DECREASES. DECREASED POPS ACROSS THE SOUTH CONSIDERABLY
UNTIL THE LATE AFTERNOON BEFORE REDEVELOPMENT BY THE AFTERNOON
BEFORE NEXT SHORTWAVE EJECTS ACROSS THE CENTRAL PLAINS AND INTO
MO/IA BY 00Z MONDAY.
DESTABILIZATION OCCURS LATE SUNDAY MORNING AND INTO THE AFTERNOON
AS THE 0-3KM ML CAPE INCREASES TO 800 TO NEAR 2000 J/KG OVER
CENTRAL AND SOUTHERN IOWA BY 00Z MONDAY WITH BREAK BETWEEN
SHORTWAVES. SURFACE BASED CAPE INCREASES TO OVER 2500 J/KG BY THE
SAME TIME AND LOCATION. LOW LEVEL SHEAR MORE FAVORABLE FOR
TORNADIC DEVELOPMENT ACROSS FAR SOUTHWEST IOWA WHERE 0-1KM SHEAR
INCREASE TO 20-25 KNOTS...MORE IN THE 10 TO 15 KNOTS RANGE FURTHER
NORTH. DEEP LAYER SHEAR FAVORABLE FOR LONG LIVED STORMS LATE
TOMORROW AFTERNOON INTO THE EVENING HOURS. KEPT MENTION OF SEVERE
WX FOR SOUTHERN PORTIONS OF THE FORECAST AREA SUNDAY LATE
AFTERNOON AND INTO THE EVENING. IN ADDITION TO SEVERE
POTENTIAL...HEAVY RAIN LOOKS IMMINENT AS WELL WITH WARM LAYER
CLOUD DEPTHS RANGING AROUND 11000 FEET AND PRECIPITABLE WATER
VALUES IN THE 1.5 TO 1.75 INCH RANGE. CORFIDI VECTORS INDICATING
TRAINING STORMS TOMORROW NIGHT LEADING TO FLASH FLOODING
POTENTIAL. STORMS LOOK TO PUSH INTO NORTHERN IOWA EARLY MONDAY
MORNING AND LOWERED POPS IN CENTRAL AND SOUTHERN IOWA.
.TUESDAY THROUGH SATURDAY...UPPER LOW BECOMES CUTOFF AND LINGERS
OVER THE REGION BEFORE FINALLY MOVES EAST BY THURSDAY MORNING.
SEVERE WEATHER CHANCES LOOK MINIMAL...BUT ADDITIONAL PERIODS OF RAIN
ARE LIKELY INTO THURSDAY. TEMPERATURES LOOK TO BE NEAR OR SLIGHTLY
BELOW NORMAL BY WEDNESDAY AND THROUGH LATE IN THE WEEK.
&&
.AVIATION...18/18Z
ISSUED AT 1246 PM CDT SAT MAY 18 2013
OVERNIGHT CONCERNS REGARDING CONVECTION AND OVERALL COVERAGE.
MODELS SUGGESTING MCS DEVELOPMENT NEAR/IN AREA BY 10-15Z SUNDAY
BUT PLACEMENT SOMEWHAT CHALLENGING FOR NOW. HAVE CONSIDERED WARM
AIR ADVECTION AND NOSE OF INCREASING SOUTHERLY JET WITH WARM
FRONTAL PLACEMENT...ALL POINTING TO DEVELOPMENT AFFECTING EITHER
KDSM OR KFOD GREATER THAN AREAS EAST/NORTH. THUS...FOR NOW HAVE
INCREASED LIKELIHOOD OF TSRA AT THOSE TWO SITES FOR EARLY MORNING
HOURS. WINDS WILL LIKELY REMAIN JUST UNDER 12KT OVERNIGHT WITH
INCREASING SOUTHERLY FLOW AFT 04Z. WITH OVERNIGHT CONVECTION...
BEGIN TO EXPECT THE MCS TO DIMINISH TOWARD THE END OF PERIOD AS
JET WEAKENS AFTER 12Z. NEXT ROUND OF CONVECTION MORE LIKELY LATE
AFTERNOON OR AFT 20/00Z AS SHORTWAVE APPROACHES FROM WEST.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...REV
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
147 PM EDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT SAT MAY 18 2013
IN THE LARGE SCALE...TROUGH OVER THE ROCKIES WILL SLIDE ONTO THE
HIGH PLAINS BY SUNDAY MORNING ALLOWING RIDGING TO SLIGHTLY BUILD
OVER THE WESTERN GREAT LAKES. ALTHOUGH SFC-H85 TROUGHING OVER THE
DAKOTAS DOES NOT MOVE MUCH TO THE EAST...IT IS ENOUGH TO INCREASE
LOW-LEVEL SOUTHERLY FLOW ACROSS THE UPPER GREAT LAKES. PATTERN IS
SERVING TO INCREASE MOISTURE /PWATS 1.15 OF 1.31 INCHES AT GRB AND
MPX OR AROUND 200 PCT OF NORMAL/ IN WAKE OF DRY SFC HIGH THAT HAS
BEEN ESTABLISHED OVER THE AREA FOR MOST OF THIS WEEK. REGIONAL RADAR
SHOWS DECAYING ECHOES OVER NORTHERN WISCONSIN. MUCH MORE ORGANIZED
AREA OF SHRA/TSRA HAVE DEVELOPED SINCE 03Z FROM CENTRAL MINNESOTA
INTO WEST CENTRAL WISCONSIN ALONG H85 WARM FRONT/GRADIENT OF H85
THETA-E. ADDITIONAL AREA OF SHRA/TSRA SPREADING ACROSS NORTHEAST
SOUTH DAKOTA INTO SOUTHEAST NORTH DAKOTA NEAR CONVECTIVE INDUCED
SHORTAVE/H7-H3 DIFFERENTIAL PVA AND CLOSE TO H7 MOISTURE TRANSPORT.
JUST RECENTLY ANOTHER LARGE CLUSTER OF SHRA/TSRA HAVE FORMED IN THE
WARM AIR ADVECTION REGIME BTWN THESE TWO INITIAL AREAS OF PRECIP.
GIVEN EXTENT OF SHRA/TSRA UPSTREAM OF CWA THIS MORNING AND SINCE
H85-H7 MOISTURE ADVECTION IS FORECAST WEST TO EAST ACROSS CWA
THROUGH THE DAY...INCREASED POPS FOR MOST OF THE WEST AND NORTHERN
CWA AS AT LEAST MULTIPLE REMNANTS OF THIS CONVECTION SHOULD MAKE IT
INTO UPR MICHIGAN. LEANED ON THE NCEP WRF MODELS AND RECENT HRRR AND
EXTRAPOLATION OF LATEST HRRR TO CREATE POPS. RESULT IS LIKELY POPS
MOST OF THE DAY OVER THE WEST HALF...WITH SMALLER CHANCES FARTHER
EAST AS THE RAIN RUNS INTO THE VERY DRY AIRMASS ASSOCIATED WITH SFC
HIGH TO THE EAST. MAJORITY OF TSRA THUS FAR STAYING OVER NORTHERN
MINNESOTA ON GRADIENT OF 1-6KM MUCAPE RESERVOIR. HINT IN MODELS
THAT EASTERN EDGE OF INSTABILITY GRADIENT SLIDES TOWARD WESTERN UPR
MICHIGAN SO HAVE INCLUDED SLIGHT CHANCES FOR TSRA. CONVECTION IS
ELEVATED AND MID-LEVEL LAPSE RATES BARELY GET ABOVE 6C/KM. MAIN
ISSUE WILL BE HEAVY DOWNPOURS AND LIGHTNING STRIKES. TEMPS TODAY
A BIT TOUGH TO FIGURE OUT. EAST GRADIENT WINDS SHOULD KEEP KEWEENAW
CHILLY WITH READINGS STAYING BLO 50 DEGREES. MIXING TO H9 IS PROBABLY
IT WHERE CLOUDS/RAIN PERSIST MOST OF THE DAY. THIS SUPPORTS MAJORITY
OF CWA SEEING HIGHS IN THE 60S...EVENTUALLY...ONCE THE STEADIER RAIN
TAPERS OFF THIS AFTN. SFC WARM FRONT MAY TRY TO POKE INTO FAR SW CWA
LATE IN THE DAY. IF THIS OCCURS AND PRECIP TAPERS OFF/ENDS...THEN
THERE IS POTENTIAL FOR HIGHS TO PUSH WELL INTO THE 70S FROM IWD TO
IMT.
H85 FRONT LIFTS NORTH OF MOST CWA THIS EVENING. KEWEENAW STILL CLOSE
ENOUGH TO FRONT AND WITHIN THE RIBBON OF PERSISTENT MOISTURE
ADVECTION SO KEPT SHRA/ISOLD TSRA THERE THROUGH THE EVENING. DRYING
TREND TAKES HOLD OVERNIGHT AS THE FOCUS FOR SHRA/TSRA...H85 WARM
FRONT AND THETA-E GRADIENT...LIFTS WELL TO NORTH OF UPR MICHIGAN.
KEPT SMALL POPS IN AT ISLE ROYALE LATE TONIGHT THOUGH. TEMPS MOSTLY
IN THE 40S EAST WITH FLOW OFF LK MICHIGAN. LESS MODIFIED AIR FARTHER
WEST ALLOWS MINS TO ONLY FALL INTO THE LOW-MID 50S ALONG LK SUPERIOR
AROUND IWD TO ONTONAGON AND EAST TO BARAGA/L`ANSE AND MARQUETTE
AREAS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 510 AM EDT SAT MAY 18 2013
NAM SHOWS THE 500 MB RIDGE OVER THE EASTERN U.S. 12Z SUN WITH
TROUGHING IN THE ROCKIES. THE TROUGH MOVES EAST ON SUNDAY AND PUSHES
THE RIDGE INTO THE LOWER GREAT LAKES 12Z MON WHERE THE MOVEMENT
EASTWARD STOPS THROUGH 12Z TUE. NAM HAS SOME DEEPER MOISTURE AND
850-500 MB Q-VECTOR CONVERGENCE OVER THE AREA 12Z SUN ONWARD. GFS
SHOWS ABOUT THE SAME THING AS WELL.
THIS PERIOD LOOKS PRETTY WET STARTING WITH SUN AFTERNOON THROUGH MON
NIGHT. WITH SLOW MOVEMENT OF SYSTEM INTO AND THROUGH THE AREA AND
ALSO A WARM FRONT NEAR AND TO THE SOUTH OF THE AREA...THIS SETS UP
THE CWA FOR A WIDESPREAD AND LONG LIVED RAIN EVENT WITH SOME HEAVY
RAIN POSSIBLE. AM FORECASTING ANYWHERE FROM .67 INCH OF QPF OVER THE
SOUTH...TO 1.15 INCHES OVER THE EAST TO OVER 2 INCHES OF RAIN IN THE
FAR WEST NEAR IRONWOOD FROM SUNDAY AFTERNOON THROUGH MONDAY NIGHT
AND THIS DOES NOT SEEM UNREASONABLE WITH PLENTY OF MOISTURE TO THE
SOUTH OF THE AREA AND SLOW SYSTEM MOVEMENT. FOR THIS REASON...BUMPED
POPS UP A BIT TO LIKELY TO CATEGORICAL FOR MOST OF THE CWA THROUGH
THEN. SHOULD SEE SOME SUNSHINE ON SUNDAY. MADE A FEW ADJUSTMENTS TO
TEMPERATURES BASED ON LAKE BREEZES AND WIND DIRECTIONS AND LOWERED
THEM A BIT NEAR THE GREAT LAKES SHORELINES. OTHER THAN THAT...NO
REAL BIG CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB CLOSED LOW AND TROUGH
IN THE NORTHERN AND CENTRAL PLAINS 12Z TUE WHICH MOVE LITTLE INTO
12Z WED. BY 12Z THU...THE TROUGH AND LOW GET PUSHED A BIT FURTHER
EAST TO THE UPPER GREAT LAKES REGION. THE TROUGH AND LOW MOVE
THROUGH BY 12Z FRI WITH RIDGING BUILDING INTO THE PLAINS LATE ON
FRI. SYSTEM WILL BE SLOW TO MOVE THROUGH THE AREA...SO A COUPLE OF
DAYS OF WIDESPREAD RAIN ARE NOT OUT OF THE QUESTION ALONG WITH
COOLER TEMPERATURES WITH GRADUAL SOUTHWARD MOVEMENT OF THE SYSTEM
AWAY FROM THE AREA. THU INTO FRI...THINGS START TO DRY OUT WITH A
COLD FRONT WELL SOUTH OF THE AREA. TEMPERATURES SLIP TO SLIGHTLY
BELOW NORMAL THIS PERIOD. POPS WILL BE HIGHEST IN THE SOUTH CLOSER
TO A WARM FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 146 PM EDT SAT MAY 18 2013
A WARM FNT MOVING IN FM THE SOUTH WILL BRING SOME -SHRA/MVFR CIGS
/LIFR CIGS AT CMX WITH UPSLOPE FLOW/...MAINLY AT IWD/CMX WHERE LLVL
WARM/MOIST ADVCTN WL BE MOST PRONOUNCED. MOIST UPSLOPE FLOW OFF LK
SUPERIOR MAY RESULT IN IFR CONDITIONS INTO THIS EVENING. FOLLOWING
THE WARM FROPA TONIGHT...EXPECT WSHFT TO THE S WITH RETURN TO
PREDOMINANT VFR WX. THE ONLY EXCEPTION WL BE AT CMX...WHERE
PERSISTENT UPSLOPE ESE WIND AND MOISTER LLVL AIR WL RESULT IN
LINGERING MVFR CONDITIONS THROUGH MUCH OF THE NIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT SAT MAY 18 2013
HEADING THRU EARLY NEXT WEEK...THE PRESSURE GRADIENT OVER THE UPPER
LAKES WILL SLOWLY TIGHTEN BETWEEN LOW PRESSURE SLOWLY MOVING FROM
THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRESSURE
BUILDING IN THE VICINITY OF WRN HUDSON BAY. THIS WILL LEAD TO
EASTERLY WINDS GRADUALLY INCREASING TO ALMOST 30 KNOTS BY MON AND
MON NIGHT...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...07
AVIATION...TITUS
MARINE...07
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
314 PM CDT SAT MAY 18 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 312 PM CDT SAT MAY 18 2013
(TONIGHT)
THE PRIMARY CONCERN TONIGHT IS POTENTIAL THUNDERSTORM DEVELOPMENT
NORTH OF A NW-SE ORIENTED WARM FRONT THAT WILL LIFT ACROSS THE CWA
OVERNIGHT. GIVEN THE UNSTABLE AIRMASS IN PLACE OVER THE REGION
/MUCAPES ON THE ORDER OF 2500-3000J/KG AS PER THE RUC...GFS...AND
LOCAL WRF MODELS FOR TONIGHT/ ADDITIONAL WAA AND A VEERING LLJ COULD
CERTAINLY PROVIDE ENOUGH LIFT TO FIRE SOME STORMS DURING THE LATE
OVERNIGHT AND EARLY MORNING HOURS. THE 4KM WRF-NNM AND HRRR DEVELOP
SCATTERED STORMS TONIGHT NORTH OF THE FRONT...PARTICULARLY THROUGH
THE 09Z-12Z TIME FRAME. THUS...HAVE MAINTAINED TRENDS IN TONIGHT`S
FORECAST...INTRODUCING SCHC POPS AFTER MIDNIGHT WITH A FOCUSED AREA
OF CHC POPS MARCHING NORTHWARD THROUGH THE LATE OVERNIGHT HOURS AND
TOWARD DAYBREAK.
OTHERWISE...ANOTHER WARM NIGHT IS AHEAD FOR THE AREA...WITH LOW
TEMPERATURES EXPECTED TO DROP INTO THE MIDDLE 60S FOR SOUTHWEST
ILLINOIS TO UPPER 60S OVER MID MISSOURI AND FOR THE STL METRO AREA.
JP
.LONG TERM...(SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
ON SUNDAY...WARM FRONT TO LIFT NORTH OF FORECAST AREA BY
MIDDAY...SO JUST HAVE SLIGHT CHANCE POPS DURING THE MORNING
HOURS...THEN BEST CHANCES OF STORMS IN CENTRAL/NORTHEAST MO...WEST
CENTRAL IL DURING THE AFTERNOON HOURS CLOSER TO THE MAIN WEATHER
SYSTEM. THE ACTIVITY RAMPS UP DURING SUNDAY EVENING AND THE
OVERNIGHT HOURS AS A SHORTWAVE ROTATES AROUND THE UPPER SYSTEM
THROUGH THE FORECAST AREA...THOUGH BEST CHANCES REMAIN OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL ON NOSE OF LOW LEVEL JET.
WITH DECENT SHEAR AND INSTABILITY...AS WELL AS LOW LEVEL
MOISTURE...SEVERE STORMS ARE POSSIBLE OVER THIS AREA...WITH THE
MAIN THREAT BEING LARGE HAIL. OTHERWISE...WITH WARM FRONT LIFTING
NORTH OF FORECAST AREA AND 850 TEMPS APPROACHING 20C...WILL SEE
TEMPS WARM UP INTO THE MID TO UPPER 80S. LOWS SUNDAY NIGHT TO
REMAIN MILD...IN THE MID TO UPPER 60S.
ON MONDAY...ACTIVITY TO TAPER OFF A BIT...BEFORE RAMPING BACK UP
LATE MONDAY AFTERNOON AND THROUGH THE OVERNIGHT HOURS WITH NEXT
SIGNIFICANT SHORTWAVE AND ANOTHER ROUND OF SEVERE WEATHER POSSIBLE.
WITH MODELS CONTINUING TO SLOW DOWN THIS SYSTEM...WILL SEE THE
STORMS PERSIST THROUGH WEDNESDAY BEFORE TAPERING OFF AS FRONTAL
BOUNDARY FINALLY MOVES THROUGH. TEMPERATURES TO REMAIN ABOVE NORMAL
THROUGH THE FIRST PART OF THE WORK WEEK...BEFORE COOLING OFF TO NEAR
NORMAL TEMPS IN THE 70S FOR THE LAST HALF OF THE WORK WEEK.
WITH SLOW EXIT OF SYSTEM AND FRONTAL BOUNDARY STALLED OUT JUST SOUTH
OF FORECAST AREA ON THURSDAY...CHANCE POPS OVER SOUTHEAST HALF OF
FORECAST AREA STILL LOOKS GOOD. OTHERWISE...DRY WEATHER EXPECTED
FRIDAY AND SATURDAY.
BYRD
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1243 PM CDT SAT MAY 18 2013
FOG HAS DISSIPATED ACROSS THE REGION...THOUGH CIGS HAVE BEEN A BIT
SLOW TO RECOVER...PARTICULARLY ACROSS NORTHEAST MO AND OVER THE
OZARKS. LATEST VISIBLE SATELLITE IMAGERY SHOWS AN EXTENSIVE
CUMULUS FIELD DEVELOPING OVER THE MISSISSIPPI VALLEY...THOUGH
EXPECT THE GRADUAL IMPROVEMENT IN CIGS TO CONTINUE THIS
AFTERNOON...WITH JUST SOME SCT VFR CLOUDS EXPECTED.
A NW-SE ORIENTED WARM FRONT WILL SHIFT NORTHWARD ACROSS THE REGION
OVERNIGHT TONIGHT...AND MODELS CONTINUE TO INDICATE THE
DEVELOPMENT OF SOME SHRA/TSRA ALONG AND AHEAD OF THE ADVANCING
WARM FRONT. FOR NOW...HAVE INCLUDED MENTION OF VCSH FOR AREA TAF
SITES DURING THE EARLY MORNING HOURS...AND WILL DEFER TO LATER TAF
ISSUANCES TO FURTHER PIN DOWN TIMING AND/OR MENTION OF TSRA.
OTHERWISE...WINDS WILL REMAIN SOUTHEASTERLY TODAY AND VEER TO
THE SOUTH ON SUNDAY...INCREASING TO ABOUT 10-12KT WITH SOME GUSTS
AS RETURN FLOW SETS IN.
SPECIFICS FOR KSTL...
CIGS ARE EXPECTED TO CONTINUE TO IMPROVE TO SCT VFR THIS
AFTERNOON...WITH LIGHT SOUTHEAST WINDS. OVERNIGHT TONIGHT A WARM
FRONT WILL DRIFT NORTH ACROSS THE AREA...AND MODELS CONTINUE TO
INDICATE SOME SHRA/TSRA DEVELOPMENT ACCOMPANYING THE FRONT. HAVE
CURRENTLY INCLUDED VCSH MENTION FOR KSTL FROM 10-13Z...THOUGH
TIMING WILL LIKELY NEED REFINED IN LATER TAF ISSUANCES...ALONG
WITH POTENTIAL THUNDER MENTION WHEN COVERAGE/INTENSITY BECOMES
MORE CLEAR. WINDS WILL VEER TO THE SOUTH TOMORROW BEHIND THE
ADVANCING WARM FRONT...INCREASING TO 10-12KT AND GUSTING TO
20-22KT BY THE AFTERNOON.
JP
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
116 PM CDT SAT MAY 18 2013
.MESOSCALE DISCUSSION...
ISSUED AT 1251 PM CDT SAT MAY 18 2013
SEVERE THUNDERSTORM POTENTIAL STILL ON TRACK THIS AFTERNOON AND
EVENING. LATEST SFC ANALYSIS HAS A SFC LOW PRESSURE CENTER LOCATED
IN EASTERN COLORADO...WITH A DRY LINE EXTENDING SOUTH FROM THE
LOW CENTER THROUGH THE TX PANHANDLE AND WARM FRONT EAST NORTHEAST
ACROSS NORTHERN KS. SFC LOW SHOULD CONTINUE TO LIFT SLOWLY
NORTHWARD TO NEAR GOODLAND BY LATE AFTERNOON A WARM FRONT WILL
ARC NORTHEAST INTO SOUTHWEST NEBRASKA FROM THE LOW CENTER.
THUNDERSTORMS SHOULD INITIATE AROUND IMPERIAL AND HAYES CENTER
AROUND 400 PM CDT ON THE NOSE OF VERY STEEP LOW LEVEL LAPSE
RATES/DRY LINE WHICH WILL BE PUNCHING INTO FAR SOUTHWEST NEBRASKA.
STORMS LIKELY TO BECOME SUPERCELLS QUICKLY AS THEY MOVE NORTHEAST
INTO A VERY TO EXTREMELY UNSTABLE AND FAVORABLE SHEARED
ATMOSPHERE. BACKED SFC WINDS TO THE SOUTHEAST ARE EXPECTED ACROSS
MOST OF SOUTHWEST NEBRASKA...WITH SPEEDS INCREASING JUST OFF THE
SFC EARLY THIS EVENING. THE TIME FRAME FROM 600 PM CDT TO 900 PM
CDT LOOKS TO BE THE MOST FAVORABLE FOR TORNADO DEVELOPMENT ACROSS
SOUTHWEST NEBRASKA. IN ADDITION TO THE TORNADO THREAT...VERY LARGE
HAIL...POSSIBLE BASEBALL SIZE OR LARGER...IS EXPECTED. STORMS WILL
LIKELY MERGE EARLY THIS EVENING INTO A COMPLEX AS THEY ADVANCE
NORTHEAST TOWARD CENTRAL AND NORTH CENTRAL NEBRASKA. LARGE HAIL
AND DAMAGING WINDS WILL BE THE MAIN THREATS FROM THE COMPLEX.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1251 PM CDT SAT MAY 18 2013
MVFR CONDITIONS WILL CONTINUE TO BE POSSIBLE ACROSS PORTIONS OF
WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON IN AREAS OF
LOWER STRATUS CLOUDS.
TSTMS...SOME SEVERE...WILL DEVELOP ACROSS SOUTHWEST NEB LATE THIS
AFTERNOON...AND SPREAD NORTHEAST ACROSS THE ENTIRE AREA THROUGH
THE EVENING. WINDS WILL BE SOUTHEAST...BUT VARIABLE AND GUSTY NEAR
ANY STORM.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...TAYLOR
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS BISMARCK ND
124 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 105 PM CDT SAT MAY 18 2013
THE DISCUSSION FROM THE PREVIOUS UPDATE REMAINS VALID AS THE MAIN
FOCUS IS STILL LOCATION AND TIMING OF CONVECTIVE INITIATION THIS
AFTERNOON.
THE ONLY NEW INFORMATION TO ADD IS THE PRESENCE OF LOW LEVEL
CONVERGENCE STRETCHING FROM DICKINSON TO BUFFALO SD. VISIBLE
SATELLITE INDICATES SOME AGITATED CUMULUS THERE...AND 18 UTC SPC
MESOANALYSIS INDICATES A MARKED INCREASE IN MIXED LAYER CAPE OVER
THE PAST HOUR. SHOULD THIS TREND CONTINUE...STRONGER STORMS MAY BE
REALIZED BY 4 PM CDT.
UPDATE ISSUED AT 1024 AM CDT SAT MAY 18 2013
THE TIMING AND LOCATION OF CONVECTIVE INITIATION IN THIS COMPLEX
SCENARIO IS THE MAIN FOCUS TODAY. PRECIPITATION CHANCES ALONG THE
MISSOURI RIVER HAVE GENERALLY BEEN LOWERED FOR THIS MORNING AND
EARLY AFTERNOON AS LOW LEVEL STRATUS WILL HELP TO STABILIZE THE
ATMOSPHERE UNTIL THE NEXT MID LEVEL SHORTWAVE ARRIVES THIS
AFTERNOON.
THE 12 AND 13 UTC HRRR HAVE PICKED UP ON THE CLEARING OVER
NORTHWESTERN SOUTH DAKOTA THIS MORNING...AND NOW INITIATES
CONVECTION THERE AND IN SOUTHWESTERN NORTH DAKOTA BY 21 UTC. 12
UTC GFS THERMODYNAMIC PROFILES SUPPORT THIS IDEA ALONG WITH THE 00
UTC ECMWF AS CAPE IS FORECAST TO EXCEED 1000 J/KG THERE.
THE CURRENT THINKING IS THAT CONVECTION WILL SPREAD GENERALLY
EAST-NORTHEASTWARD UNTIL MID/LATE AFTERNOON DESTABILIZATION AND
MIDDLE LEVEL HEIGHT FALLS FINALLY INITIATE ADDITIONAL CONVECTION
BETWEEN THE MISSOURI AND JAMES RIVERS ALONG THE DAKOTA BORDER.
UPDATE ISSUED AT 644 AM CDT SAT MAY 18 2013
UPDATE MAINLY FOR POP TRENDS TODAY. SHOWERS AND ISOLATED STORMS
HAVE PUSHED INTO THE FAR NORTHEAST EARLY THIS MORNING. RECENT RUNS
OF THE RAP HAVE A GOOD HANDLE ON NEAR TERM TRENDS...AND HAVE
REDUCED POPS THROUGH THE MORNING INTO EARLY AFTERNOON. STILL
EXPECTING THE FOCUS OF AFTERNOON CONVECTION ALONG A BOUNDARY TO
THE SOUTHEAST...WITH POTENTIAL FOR SOME SEVERE STORMS TO DEVELOP
BY MID AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 105 PM CDT SAT MAY 18 2013
LOW STRATUS HAS BEEN VERY DIFFICULT TO FORECAST TODAY...BUT
SHOULD LIFT AT ALL SITES BY 20 UTC. SHOWERS AND THUNDERSTORMS WILL
CAUSE MVFR CONDITIONS AT MOST TAF SITES TODAY...WITH BRIEF PERIODS
OF IFR POSSIBLE IN STRONGER STORMS. IFR/LIFR FOG AND LOW STRATUS
WILL LIKELY RETURN AFTER MIDNIGHT TONIGHT IN THE WAKE OF
PRECIPITATION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...SCHECK
SHORT TERM/LONG TERM...RP KINNEY
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
119 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 107 PM CDT SAT MAY 18 2013
AREA OF RAIN CONTINUES TO LIFT SLOWLY NORTH AND IS NOW ALONG THE
CANADIAN BORDER. NO MODEL REALLY HINTED AT THIS MUCH FROM 00Z AND
12Z RUNS. REST OF AREA DRY SOUTH OF HIGHWAY 2. SOME CLEARING IN SE
ND WORKING NORTH A BIT...AND IN THIS CLEAR AREA TEMPS IN THE 77 TO
80 DEGREE RANGE FROM TENNEY-WAHPETON TO FARGO-VALLEY CITY. DEW PTS
RANGE FROM UPPER 50S TO MID 60S IN THIS AREA. IT IS THIS AREA
WHICH WILL SEE CAPES 1500-2000 J/KG LATE TODAY...AND COULD SEE
STORM DEVELOPMENT. 12Z SPC WRF SHOWS SOME DEVELOPMENT FAR-DTL 22Z-
00Z WHEREAS HRRR SHOWS IT MORE AXN-BRD REGION. UPDATED POPS TO
SHOW THIS INCREASE IN POPS IN THE FAR SOUTH-SOUTHEAST AFTER 22Z.
DISC WITH WFO DLH/MPX WILL HOLD OFF ANY FFA FOR NOW HAS HEAVIEST
CONVECTION EARLIER THIS MORNING-LAST NIGHT WAS AXN-STC-BRD REGION
JUST TO OUR SOUTH.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 326 AM CDT SAT MAY 18 2013
FORECAST CHALLENGE THROUGH THE SHORT TERM WILL CONTINUE TO BE PCPN
CHANCES AS WELL AS SEVERE STORM AND HEAVY RAIN POTENTIAL. MODELS
IN FAIR AGREEMENT WITH MAIN FEATURES HOWEVER SUBTLE DIFFERENCES
EXIST WITH SURFACE LOW/BOUNDARY POSITIONS TODAY.
ARC OF WEAKENING CONVECTION LIFTING NE THROUGH FA AT 30KTS WILL
CONTINUE TO PROPAGATE NE THROUGH THE MORNING AND INTO EARLY
AFTERNOON. WILL ATTEMPT TO ADJUST/TIME POPS ACCORDINGLY.
TEMPERATURES WILL BE TRICKY AND DEPENDENT ON DEGREE OF CLOUD COVER
AND HOW FAR NORTH WARM FRONT GETS. WITH WARM COLUMN ANY BREAKS
WILL REALLY BOOST TEMPERATURES.
LATER TODAY AND INTO TONIGHT. SURFACE INVERTED TROUGH TO SHARPEN
ACROSS FA PROVIDING GOOD SOURCE OF LOW LEVEL CONVERGENCE. TOUGH TO
DETERMINE ANY SPECIFIC SHORT WAVE HOWEVER REGION COMES UNDER
ENTRANCE REGION OF MODEST JET STREAK WHICH WILL AID IN UPPER
SUPPORT. MODELS DIFFER ON LOCATION OF SURFACE LOW WHICH WILL RIDE
NORTHWARD ALONG TROUGH AS WELL AS POSITION OF WARM FRONTAL
BOUNDARY. MODELS INDICATING GOOD SURFACE MOISTURE FLUX WITH 60
DEWPOINTS SPREADING NORTHWARD THROUGH MOST OF FA. PRECIPITABLE H2O
VALUES INCREASE TO AROUND 1.5 BY EVENING. GREATEST INSTABILITY AND
CAPE ACROSS SOUTH HALF OF FA AND LOOKS TO BE THE FAVORED LOCATION
FOR SEVERE POTENTIAL. SOME CAPPING MAY INITIALLY DELAY CONVECTIVE
INITIATION DURING THE AFTERNOON. HEAVY RAIN POTENTIAL THERE BUT WITH
DIFFERENCES IN SURFACE LOW POSITION TO ENHANCE LOW LEVEL
CONVERGENCE NOT AS CLEAR CUT.
INVERTED TROUGH TO DRIFT EAST SUNDAY WHICH WILL PUT HEAVIER RAIN
THREAT INTO MN. TEMPERATURES TO BE QUITE A BIT COOLER ON BACK SIDE
OF INVERTED TROUGH.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 326 AM CDT SAT MAY 18 2013
CUT OFF LOW TAKES OVER AND DRIFTS ACROSS E SD INTO S MN TO START WORK
WEEK FOR CONTINUED MODERATE RAIN POTENTIAL AND COOLER TEMPERATURES.
TUESDAY-FRIDAY...THE UPPER LOW WILL SLOWLY SHIFT EASTWARD FROM THE
CENTRAL/NORTHERN PLAINS INTO THE GREAT LAKES DURING THIS PERIOD. THE
00Z GFS/12Z ECMWF BEGIN TO SHIFT SHOWER ACTIVITY SOUTH AND EAST ON
WEDNESDAY...WITH THE GEM SLOWER IN ENDING THE PRECIP. WILL CONTINUE
TO MENTION POPS ACROSS THE SOUTHEAST THROUGH WEDNESDAY NIGHT. SFC
HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE AREA TOWARDS THE END
OF THE WEEK AS MID/UPPER LEVEL RIDGING DEVELOPS ACROSS THE PLAINS.
BELOW NORMAL TEMPS WILL MODERATE BACK TO NEAR NORMAL BY LATE NEXT
WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 107 PM CDT SAT MAY 18 2013
ACROSS NERN ND AND NRWN MN...AREAS OF IFR TO LIFR CIGS AND VSBYS
ALG AND NORTH OF U.S. HWY 2 WILL SLOWLY LIFT AND SHIFT NORTHWARD
THIS AFTERNOON...WITH SCT MVFR CIGS LIKELY TO PERSIST INTO THE
EVENING. SCT TSTMS ARE EXPECTED TO DEVELOP FROM LATE AFTERNOON
INTO THE EARLY EVENING...BECOMING MORE NUMEROUS INTO THE LATE
EVENING. ACROSS SERN ND INTO WCNTRL MN...AREAS OF LIFR TO IFR CIGS
AND VSBYS ALG AND EAST OF AN AXN-BJI LINE WILL SLOWLY LIFT AND
SHIFT NORTHEASTWARD THROUGH THIS AFTERNOON...WITH SCT MVFR CIGS
LIKELY TO PERSIST INTO THE EVENING. OTHERWISE...FAIR SKIES OVER
THE SOUTHERN RRV WILL ALLOW FOR INCREASED SFC HEATING AND THE
DEVELOPMENT OF SCT TSTMS /WITH ISOLD LARGE HAIL/ FROM MID
AFTERNOON INTO THE EARLY EVENING...BECOMING MORE NUMEROUS INTO
MIDNIGHT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...RIDDLE
SHORT TERM...VOELKER
LONG TERM...MAKOWSKI/VOELKER
AVIATION...GUST
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
619 PM EDT SAT MAY 18 2013
.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND WILL MAINTAIN A RIDGE OVER THE
EASTERN GREAT LAKES INTO SUNDAY BEFORE SHIFTING OFF THE COAST. MEANWHILE
A NEARLY STATIONARY FRONT ACROSS SOUTHERN OHIO WILL LIFT BACK NORTH
LATE SUNDAY. SOUTHERLY FLOW WILL BRING MORE HUMID AIR EARLY IN THE
WEEK AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. THE FRONT
SHOULD ARRIVE LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
NO SIGNIFICANT CHANGES TO FORECAST FOR THE UPDATE.
PREVIOUS...LIGHT SHOWERS CONTINUE TO DIMINISH ACROSS NORTH
CENTRAL OHIO AND SPC RUC ANALYSIS SHOWS INSTABILITY LIMITED TO
SOUTHERN OHIO. SATELLITE AND RADAR IMAGERY SUPPORT THAT WITH
SHOWERS DEVELOPING CLOSER TO THE OHIO RIVER. THE FORECAST THROUGH
THE REMAINDER OF THE EVENING WILL ONLY CARRY A CHANCE OF SPRINKLES
SOUTH OF A FDY-MFD-CAK LINE. OTHERWISE EXPECT CLOUD COVER TO
GRADUALLY DIMINISH THROUGH LATE EVENING...WITH SOME INCREASE
POSSIBLE FROM THE SOUTH LATE TONIGHT. TEMPERATURES WILL BOTTOM OUT
IN THE UPPER 50S TO NEAR 60 DEGREES.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
WEAK UPPER LEVEL DISTURBANCE SLOWLY SHIFTS TO THE EAST COAST THROUGH
SUNDAY NIGHT. MODELS SHOW THE STALLED FRONTAL BOUNDARY OVER THE OHIO
VALLEY SHIFTING BACK NORTH LATE SUNDAY WHICH WILL ALLOW LOW LEVEL
MOISTURE TO INCREASE. STILL NO OBVIOUS FORCING MECHANISM ON SUNDAY
AFTERNOON TO KICK OFF SHOWERS AND THUNDERSTORMS BENEATH THE BUILDING
RIDGE ALOFT SO WILL CONTINUE TO HOLD ONTO FAIRLY LOW POPS...WITH
BEST CHANCES FOCUSED SOUTH OF A FDY-YNG LINE. EXPECTING A LITTLE
LESS CLOUD COVER...ESPECIALLY IN NW OHIO WITH HIGHS RANGING FROM THE
UPPER 70S TO LOW 80S. ALTHOUGH MODELS ARE DRY ON SUNDAY NIGHT...HAVE
ADDED IN A LOW POP TO NW OHIO AS THETA E RIDGE LIFTS NORTH INTO THE
AREA. MODELS OFTEN STRUGGLE WITH DETECTING NOCTURNAL SHOWERS IN THIS
PATTERN AND NAM SOUNDINGS SHOW A FAIR AMOUNT OF ELEVATED INSTABILITY
TO WORK WITH. WILL CONTINUE THIS SLIGHT CHANCE EASTWARD ACROSS THE
AREA THROUGH MONDAY MORNING.
UPPER LEVEL LOW WILL DEVELOP OVER THE PLAINS ON SUNDAY AND SLOWLY
PUSH EASTWARD DURING THE EARLY PART OF NEXT WEEK. DEEP SOUTHERLY
FLOW WILL RESULT IN A MOISTENING AIRMASS WITH INCREASING CHANCES OF
SHOWERS AND THUNDERSTORMS. WITH THE RIDGE OVERHEAD...SLOWLY SHIFTING
EAST OF THE AREA...THE BETTER CHANCES OF SHOWERS AND THUNDERSTORMS
WILL BE ACROSS NORTHERN PORTIONS OF THE FORECAST AREA AS ENERGY
EJECTS OUT OF THE TROUGH AND TRIES TO MOVE AROUND THE RIDGE. MONDAY
WILL LIKELY BE CAPPED FOR MOST AREAS WITH CHANCES INCREASING ON
TUESDAY. TEMPERATURES WARM INTO THE MID 70S ON MONDAY...THEN DROP
BACK INTO THE LOW 80S ON TUESDAY AS CLOUDS AND THUNDERSTORMS
INCREASE. LOWS WILL BE MILD AS DEWPOINTS CREEP UP...DROPPING INTO
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
COMPLEX WEATHER PATTERN CONTINUES FOR THE EXTENDED PERIOD. THE
MODELS CONTINUE TO SHOW A SLOW MOVING STORM SYSTEM JUST TO THE WEST
OF THE FORECAST AREA. IT APPEARS MUCH OF THE FORECAST AREA WILL BE
IN THE WARM SECTOR IN ADVANCE OF THE STORM AS IT MOVES EAST. THE
UPPER LEVEL SHORT WAVE WILL MOVE ACROSS THE REGION WEDNESDAY NIGHT
INTO THURSDAY. THE 12Z RUN OF THE GFS IS SLOWER WITH THE
PROGRESSION OF THIS STORM THAN IT WAS YESTERDAY. THE BEST LIFT FROM
THE SURFACE FRONT AND UPPER LEVEL LOW APPEARED TO BE MORE ON
WEDNESDAY YESTERDAY AND IT LOOKS MORE LIKE WEDNESDAY NIGHT AND
THURSDAY WITH THIS RUN. IN EITHER CASE...THE MIDDLE PART OF NEXT
WEEK WILL BE UNSETTLED WITH SCATTERED STORMS THROUGHOUT. THE SLOWER
PROGRESSION OF THIS MODEL RUN WILL FORCE ME TO PUT SHOWERS IN THE
FORECAST THROUGH THE END OF NEXT WEEK.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
VFR CONDITIONS OVER THE TAF LOCATIONS WITH BKN/OVC MID TO HIGH
CLOUDS OVER MOST SITES. DEW POINT GRADIENT OVER THE CENTRAL
SECTIONS OF OHIO HAS MOVED A LITTLE FURTHER NORTH TODAY. I EXPECT
THE SHOWERS AND THUNDERSTORMS THAT FORMED ALONG THIS BOUNDARY TO
BE A LITTLE FURTHER NORTH THIS AFTERNOON. I WILL PLACE VCTS IN THE
SOUTHERN AND WESTERN TAF SITES INCLUDING TOL...FDY...MFD AND CAK.
VFR CONDITIONS SHOULD PERSIST OVERNIGHT. WITH THE HIGHER DEW
POINTS CREEPING NORTH IT IS POSSIBLE THAT SOME MVFR VSBYS COULD
FORM. WINDS WILL CONTINUE FROM A GENERAL EAST DIRECTION. TAF
LOCATIONS ALONG THE LAKE INCLUDING CLE AND ERI WILL SEE AN
AFTERNOON LAKE BREEZE THAT WILL SHIFT WINDS TO THE A NORTH TO
NORTHEAST DIRECTION.
.OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THAT DEVELOP THROUGH
WEDNESDAY AND IN FOG THAT MAY OCCUR AROUND DAYBREAK.
&&
.MARINE...
EAST TO NORTHEAST WINDS CONTINUE OVER THE LAKE THIS AFTERNOON. A
FEW LOCATIONS REPORTING WIND SPEEDS IN THE 15 TO 20 KNOT RANGE.
THESE CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE EARLY EVENING
HOURS. THE 12Z BUFKIT RUN SHOWS A POCKET OF 20 TO 30 KNOT WINDS
WITHIN 1KFT OF THE SURFACE OVER THE WESTERN BASIN THROUGH 00Z. WITH
THE EAST TO NORTHEAST FETCH WAVE HEIGHTS COULD REACH 3 TO 5 FEET
OVER THE WEST. EVEN THOUGH THE CONDITIONS ARE MARGINAL...I WILL
CONTINUE THE SMALL CRAFT ADVISORY THROUGH THE EVENING. WINDS WILL
DECREASE OVERNIGHT TO 10 TO 15 KNOTS. A SIMILAR PATTERN WILL SETUP
ON SUNDAY BUT THE PRESSURE GRADIENT SHOULD BE WEAKER AND THEREFORE
THE WINDS NOT AS STRONG. I DO NOT ANTICIPATE SMALL CRAFT CRITERIA
FOR SUNDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LEZ142>145.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC/TK
SHORT TERM...KEC
LONG TERM...GARNET
AVIATION...GARNET
MARINE...GARNET
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1241 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 1104 AM CDT SAT MAY 18 2013
GOING FORECAST IS IN GOOD SHAPE. INCREASED THE SKY COVER A BIT IN
OUR WESTERN AND NORTHERN ZONES THROUGH EARLY AFTERNOON AS VERY
LIGHT CONVECTION CONTINUES TO DIE IN THOSE AREAS. THIS MAY IMPACT
HIGH TEMPERATURES A LITTLE BIT. FOR NOW...SHAVED DOWN HIGHS AROUND
A CATEGORY THROUGHOUT THE NORTHWEST HALF OF OUR AREA AS
TEMPERATURES ARE STILL IN THE 60S TO AROUND 70 UNDERNEATH THE
CLOUD COVER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1236 PM CDT SAT MAY 18 2013
LOW PRESSURE WILL BE MEANDERING AROUND NORTH CENTRAL NEBRASKA AND
CENTRAL SOUTH DAKOTA THROUGH THE TAF PERIOD. THUNDERSTORM
DEVELOPMENT WILL BE LIKELY...WITH SEVERE WEATHER A THREAT...AS THE
EVENING PROGRESSES AND LASTING INTO LATE TONIGHT AND EARLY SUNDAY.
HOWEVER CONFIDENCE IS VERY LOW ON EXACT DETAILS AND TIMING ON HOW
THE CONVECTION WILL EVOLVE OVER TIME. FOR THE TAFS...TOOK A MODEL
BLEND OF THE NAM12...GEM REGIONAL AND GFS MODELS TO COME UP WITH
SOME TIMING OF THE CONVECTION IMPACTING THE AIRPORT SITES. BUT
AGAIN THIS WILL HAVE TO MONITORED CLOSELY. THE THUNDERSTORMS WILL
HAVE THE STRONG POTENTIAL TO SEND CONDITIONS DOWN INTO THE MVFR
RANGE...AND PROBABLY EVEN SOME SHORTER TERM IFR CONDITIONS WHERE
THE HEAVIER RAIN CELLS ARE. FURTHERMORE...THERE MAY EVEN BE SOME
IFR TO MVFR STRATUS SUNDAY MORNING IN THE RAIN COOLED AIR MASS...
ESPECIALLY EAST OF THE JAMES RIVER VALLEY. THE NAM HUMIDITY TIME
SECTIONS ARE STRONGLY HINTING AT THIS SCENARIO. BACKING UP CLOSER
TO THE NEAR TERM...WOULD NOT BE SURPRISED TO SEE SOME SHOWERS AND
ISOLATED THUNDERSTORMS IN NORTHWEST IOWA LATE THIS AFTERNOON AND
EARLY EVENING UNDER CUMULUS DEVELOPMENT.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...MJF
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...MJF
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
152 PM CDT SAT MAY 18 2013
.UPDATE...FOR 18Z TAFS.
&&
.AVIATION...
LOW-LEVEL MOISTURE AND A SFC/LOW-LEVEL BOUNDARY EXPECTED TO
REMAIN IN THE IMMEDIATE VICINITY THE NEXT 24HRS. THAT WILL
CONTINUE TREND OF PERIODIC SHOWERS/STORMS. ADDITIONALLY...
CEILINGS/VSBYS EXPECTED TO DROP INTO MVFR/IFR RANGE TONIGHT
...ESPECIALLY CSV WHERE MOISTURE DEEPER AND CONVECTION EXPECTED
TO BE MORE NUMEROUS. IMPROVEMENT WILL OCCUR LATE SUN MORNING.
&&
.PREV DISCUSSION... /ISSUED 1131 AM CDT SAT MAY 18 2013/
MESOSCALE UPDATE...CELLS ARE NOW STARTING TO DEVELOP MAINLY EAST
OF I-65, WHERE LOW-LEVEL MOISTURE IS A LITTLE MORE PLENTIFUL. LAPS
SOUNDING FOR BNA VALID AT 15Z ALREADY SHOWS A LIFTED INDEX OF -3.6
AND A CONVECTIVE AVAILABLE POTENTIAL ENERGY OF 1896 J/KG. K-INDEX
IS A LITTLE LOW AT JUST 23, OWING MAINLY TO DRY AIR ABOVE ABOUT
850 MB. NAM SHOWS THE UPPER TROUGH SITUATED JUST EAST OF MIDDLE
TENNESSEE, WITH A RIDGE OF HIGH PRESSURE WEST OF THE MISSISSIPPI,
PLACING THE MID STATE UNDER A NW FLOW ALOFT, WHICH SHOULD HELP
FURTHER STEEPEN OUR MID-LEVEL LAPSE RATES. RUC MODEL SOUNDINGS FOR
THIS AFTERNOON SHOW THE LI DROPPING TO BETWEEN -5 AND -6, WITH
CAPES EXCEEDING 2500 J/KG DURING THE MOST UNSTABLE PARTS OF THE
DAY. FULLY EXPECT CONVECTION TO CONTINUE DEVELOPING. CURRENT
FORECAST OF LIKELY POP`S ALONG AND JUST WEST OF THE PLATEAU, WITH
SCATTERED POP`S ELSEWHERE, APPEARS TO BE JUSTIFIED. SPC IS KEEPING
MIDDLE TENNESSEE UNDER GENERAL THUNDERSTORMS. BELIEVE MOST
AFTERNOON STORMS WILL BE STRONG AT MOST, ALTHOUGH ISOLATED SEVERE
STORMS CERTAINLY CAN`T BE RULED OUT.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1131 AM CDT SAT MAY 18 2013
.MESOSCALE UPDATE...CELLS ARE NOW STARTING TO DEVELOP MAINLY EAST
OF I-65, WHERE LOW-LEVEL MOISTURE IS A LITTLE MORE PLENTIFUL. LAPS
SOUNDING FOR BNA VALID AT 15Z ALREADY SHOWS A LIFTED INDEX OF -3.6
AND A CONVECTIVE AVAILABLE POTENTIAL ENERGY OF 1896 J/KG. K-INDEX
IS A LITTLE LOW AT JUST 23, OWING MAINLY TO DRY AIR ABOVE ABOUT
850 MB. NAM SHOWS THE UPPER TROUGH SITUATED JUST EAST OF MIDDLE
TENNESSEE, WITH A RIDGE OF HIGH PRESSURE WEST OF THE MISSISSIPPI,
PLACING THE MID STATE UNDER A NW FLOW ALOFT, WHICH SHOULD HELP
FURTHER STEEPEN OUR MID-LEVEL LAPSE RATES. RUC MODEL SOUNDINGS FOR
THIS AFTERNOON SHOW THE LI DROPPING TO BETWEEN -5 AND -6, WITH
CAPES EXCEEDING 2500 J/KG DURING THE MOST UNSTABLE PARTS OF THE
DAY. FULLY EXPECT CONVECTION TO CONTINUE DEVELOPING. CURRENT
FORECAST OF LIKELY POP`S ALONG AND JUST WEST OF THE PLATEAU, WITH
SCATTERED POP`S ELSEWHERE, APPEARS TO BE JUSTIFIED. SPC IS KEEPING
MIDDLE TENNESSEE UNDER GENERAL THUNDERSTORMS. BELIEVE MOST
AFTERNOON STORMS WILL BE STRONG AT MOST, ALTHOUGH ISOLATED SEVERE
STORMS CERTAINLY CAN`T BE RULED OUT.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1237 PM CDT SAT MAY 18 2013
.DISCUSSION...
SEE AVIATION DISCUSSION BELOW.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL ACROSS MUCH OF THE AREA. JUNCTION
MAINTAINS MVFR VISIBILITY...THOUGH AS WINDS HAVE PICKED UP ACROSS
WEST CENTRAL TEXAS DUE TO A TIGHT SURFACE PRESSURE GRADIENT...THE
HAZE WILL MIX OUT. WINDS WILL DROP OFF EARLY THIS EVENING AS THE
PRESSURE GRADIENT RELAXES. ISOLATED THUNDERSTORMS ARE POSSIBLE
THIS AFTERNOON...HOWEVER GIVEN THE ISOLATED NATURE NOT MENTIONING
IN TAFS RATHER WILL AMEND AS NEEDED. JUNCTION WILL SEE SOME
MOISTURE RETURN OVERNIGHT PRODUCING MVFR CONDITIONS AGAIN.
&&
.PREV DISCUSSION... /ISSUED 606 AM CDT SAT MAY 18 2013/
DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.
AVIATION...
MID LEVEL CLOUD COVER WILL PERSIST THROUGH MID MORNING BEFORE
BEING REPLACED BY A HIGH BASED CU FIELD THAT WILL CONTINUE THROUGH
EARLY EVENING. WINDS WILL BE PREDOMINANTLY FROM THE SOUTH /170-200
DEGREES/ AND WILL INCREASE TO 15-20 KTS BY 14-15Z. I EXPECT WIND
SPEEDS TO STAY THROUGHOUT THE DAY. WINDS WILL STAY UP THIS EVENING
AT KABI/KSJT AS THE LOW LEVEL JET REDEVELOPS. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS WILL BE POSSIBLE ALONG AND EAST OF THE
DRYLINE. HOWEVER...COVERAGE SHOULD BE LIMITED SO NO THUNDER WAS
INCLUDED AT ANY PARTICULAR TAF SITE. HOWEVER...KABI AND KBBD STAND
THE BEST CHANCE OF SEEING THIS ACTIVITY /ALBEIT STILL A LOW
CHANCE/. WILL WAIT FOR THE DETAILS TO EMERGE BEFORE INCLUDING
RESTRICTIONS IN THE TAFS.
JOHNSON
PREV DISCUSSION... /ISSUED 417 AM CDT SAT MAY 18 2013/
SHORT TERM...
NEAR RECORD TEMPERATURES AND POTENTIAL SEVERE CONVECTION HIGHLIGHT
THE SHORT TERM PORTION OF THE FORECAST.
PRONOUNCED SOUTHWEST FLOW ALOFT IS EVIDENT PER 00Z UPPER AIR
ANALYSIS. SHORTWAVE RIDGING OVER THE PLAINS THAT HAS SHARED SOME
RESPONSIBILITY FOR OUR OPPRESSIVE HEAT WILL SHIFT SLOWLY EAST AS A
TROUGH MOVES ACROSS THE ROCKIES. THIS TROUGH IS TAKING ON
SOMEWHAT OF A NEGATIVE TILT BUT THE STRONGEST WINDS ALOFT REMAIN
ON ITS WESTERN FLANK. A SUBTROPICAL JET STREAK IS PROPAGATING
NORTHEAST ACROSS MEXICO THIS MORNING AND SHOULD ARRIVE THIS
EVENING. IN THE LOWER TROPOSPHERE...STRONG LEE CYCLOGENESIS HAS
ENHANCED THE NOCTURNAL LOW LEVEL JET WHICH IS CONTINUING TO PUMP
GULF MOISTURE NORTH INTO THE SOUTHERN PLAINS. DEWPOINTS ARE IN THE
60S TO LOWER 70S ACROSS THE CWA. THE DRYLINE IS CURRENTLY FOUND TO
OUR WEST AND WILL MOVE A BIT TO THE EAST TODAY. THE QUESTION
REMAINS HOW FAR EAST. MOST OF THE 00Z GUIDANCE MIXES THE DRYLINE
AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO OZONA LINE.
HOWEVER...SEVERAL OF THE HIRES CAMS HOLD THE DRYLINE FARTHER WEST
ALONG THE WESTERN BORDER OF THE CWA. GIVEN THE LACK OF A STRONG
MID LEVEL JET ROUNDING THE BASE OF THE TROUGH THROUGH EARLY
AFTERNOON /AND COLLABORATION WITH NEIGHBORING OFFICES/ I HAVE
OPTED FOR THE WESTERN PLACEMENT OF THE DRYLINE...KEEPING MOST OF
THE AREA WITHIN THE MOIST SECTOR.
THE 00Z GUIDANCE SUGGESTS TEMPS WILL BE 5-7 DEGREES COOLER THAN
YESTERDAY. HOWEVER...THE RAP WARMS SURFACE TEMPS UP TO NEAR 105
DEGREES AGAIN. WHILE THE INCREASE IN MID LEVEL CLOUDS AND
ADDITIONAL MOISTURE ON THE EAST SIDE OF THE DRYLINE WILL LIMIT
HEATING...I STILL DO NOT THINK WE WILL COOL OFF BY THAT MUCH. I
WENT WITH A COMPROMISE BETWEEN THE NAM AND RAP...WITH FORECAST
HIGHS GENERALLY 97 TO 101 DEGREES. INSTABILITY PARAMETERS ACROSS
THE AREA ARE IMPRESSIVE WITH MLCAPE VALUES OF 2000-3000 J/KG THIS
AFTERNOON. DEEP LAYER SHEAR LOOKS JUST SUFFICIENT FOR
SUPERCELLULAR ACTIVITY WITH AN ANTICIPATED 25-30 KTS OF 0-6KM
SHEAR. WITH THE INTENSE SURFACE HEATING...WE SHOULD SEE SEVERAL
UPDRAFTS PENETRATE THE CAP AND MATURE QUICKLY INTO POTENTIALLY
SEVERE THUNDERSTORMS. STEEP MID LEVEL LAPSE RATES WILL LEND TOWARD
A LARGE HAIL THREAT WITH ADIABATIC LAPSE RATES AND A DEEP...DRY
SUB CLOUD LAYER PROVIDING A WIND THREAT. THE EXTREMELY HIGH CLOUD
BASES WILL LIMIT THE TORNADO POTENTIAL THIS FAR SOUTH...BUT WILL
NOT RULE OUT THE THREAT ALTOGETHER. THE GREATEST POTENTIAL FOR
SEVERE WEATHER WILL BE ACROSS THE BIG COUNTRY WHERE THE CAP WILL
BE A BIT WEAKER BUT THE THREAT WILL EXIST AREAWIDE.
TONIGHT...ANY ONGOING CONVECTION WILL MOVE IN A GENERAL
NORTHEASTERLY DIRECTION AND MAY HANG ON FOR SEVERAL HOURS AFTER
SUNSET GIVEN THE ANTICIPATED INTERACTION OF THE LOW LEVEL
JET...DRYLINE AND INCREASING SYNOPTIC SCALE ASCENT. THE SEVERE
THREAT WILL CONTINUE AS WELL BUT WILL DECREASE ONCE WE LOSE
SURFACE HEATING. EXPECT OVERNIGHT TEMPERATURES TO FALL INTO THE
LOWER 70S FOR THE MOST PART WITH SOUTH WINDS OF 5 TO 15 MPH.
THANKS LUB FOR THE COORDINATION.
JOHNSON
LONG TERM...
NOT A LOT OF CHANGE NEXT WEEK. KEPT TEMPERATURES ABOVE GUIDANCE
ON SUNDAY...WITH SUBSIDENCE AS THE UPPER TROUGH MOVES EAST. A
LARGE...SLOW MOVING UPPER LOW IS EXPECTED TO DEVELOP OVER THE
CENTRAL AND UPPER MIDWEST EARLY NEXT WEEK. WEST CENTRAL TEXAS
WILL BE SOMEWHAT DRY SLOTTED BEING SOUTH SIDE OF THE UPPER LOW.
HOWEVER...THERE MAY STILL BE ENOUGH LOW LEVEL MOISTURE AROUND TO
GENERATE A FEW THUNDERSTORMS. THE BEST CHANCE OF STORMS IS ON
TUESDAY AS A WEAK COLD FRONT AND UPPER SHORTWAVE MOVE ACROSS THE
REGION. CAN NOT RULE OUT A FEW DRYLINE THUNDERSTORMS ON
MONDAY...AND ON THURSDAY INTO FRIDAY. WILL HOLD OFF MENTION OF
STORMS ON THESE DAYS HOWEVER ...AS RAINFALL POTENTIAL IS FAIRLY
LOW. I AM ALSO CONCERNED WITH UPPER RIDGING TAKING PLACE IN THE
SECOND HALF OF NEXT WEEK...WHICH WOULD ACT TO INHIBIT CONVECTION.
04
FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS ARE ANTICIPATED TODAY ACROSS MOST
OF WEST CENTRAL TEXAS AS TEMPERATURES WARM TO NEAR 100 DEGREES...
MINIMUM RELATIVE HUMIDITIES FALL TO 20-30 PERCENT AND SOUTH 20 FT
WINDS INCREASE TO AROUND 15-20 MPH. IN ADDITION...ISOLATED AFTERNOON
THUNDERSTORMS WILL BE POSSIBLE WHICH MAY RESULT IN OCCASIONAL CLOUD
TO GROUND LIGHTNING. RELATIVE HUMIDITIES WILL RECOVER TO 70-80
PERCENT OVERNIGHT BUT WILL TANK AGAIN ON SUNDAY AS TEMPERATURES SOAR
TO NEAR OR ABOVE 100 DEGREES YET AGAIN. ON SUNDAY AFTERNOON...THE
DRYLINE WILL MOVE A BIT FARTHER EAST...SPREADING SUB 20 PERCENT
RELATIVE HUMIDITIES AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO
OZONA LINE. SOUTHWEST 20 FT WINDS WILL BE AROUND 15 MPH...RESULTING
IN ELEVATED FIRE WEATHER CONDITIONS. EXPECT CONDITIONS TO IMPROVE
ONLY SLIGHTLY ON MONDAY BUT COOLER TEMPERATURES ARE ANTICIPATED BY
TUESDAY WHICH SHOULD ALLEVIATE FIRE WEATHER CONCERNS TEMPORARILY.
JOHNSON
CLIMATE...
THE MAX TEMP YESTERDAY IN SAN ANGELO OF 106 DEGREES SMASHED THE
PREVIOUS RECORD OF 100. LIKEWISE...ABILENE SET A NEW RECORD AS
WELL...TOPPING OUT AT 104 AND BESTING THE PREVIOUS MARK OF 101
DEGREES. WE MAY BE IN LINE FOR RECORD HIGH MINIMUM TEMPS THIS
MORNING. THE RECORDS OF 73 DEGREES AT BOTH ABILENE AND SAN ANGELO
MAY FALL AS 2 AM TEMPS ARE STILL IN THE 80S.
THIS AFTERNOON...MAX TEMPS ARE FORECAST TO WARM TO NEAR OR JUST
ABOVE 100 DEGREES. MAX TEMPS RECORDS ARE IN JEOPARDY AT BOTH
SITES. ABILENE HAS A RECORD HIGH TODAY OF 99 DEGREES WHILE SAN
ANGELO/S RECORD IS 102.
JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 100 71 97 69 94 / 20 20 5 10 10
SAN ANGELO 101 72 102 70 96 / 20 10 5 5 5
JUNCTION 97 70 99 71 91 / 10 10 10 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
REIMER
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1227 PM CDT SAT MAY 18 2013
.AVIATION...
THE NORTH/CENTRAL TEXAS TAF SITES WILL BE BREEZY AND
VFR THIS AFTERNOON THROUGH LATE TONIGHT. THEN...MVFR CIGS ARE
EXPECTED TO ADVECT ACROSS THE SITES...AROUND 09Z AT KACT AND BY 11Z
ACROSS THE METROPLEX. THIS IS DUE TO A STRENGTHENING LLJ TONIGHT
THAT WILL BE IN THE 40-45 KNOT RANGE LATE TONIGHT THROUGH SUNDAY MORNING.
WINDS ARE EXPECTED TO BE AROUND 18KTS WITH HIGHER GUSTS THIS
AFTERNOON...SLIGHTLY WEAKER THIS EVENING THEN INCREASING BY 06Z TO
17G27KT. WINDS ON SUNDAY SHOULD BE 20G30KTS OR JUST A BIT HIGHER
MIDDAY THROUGH LATE AFTERNOON.
A SHORTWAVE MAY DEVELOP SOME ELEVATED CONVECTION NORTH OF I-20
LATE TONIGHT. DUE TO FORECAST SOUNDING PROFILES...WE HAVE A
CONCERN ABOUT THE POTENTIAL OF HEAT BURSTS RESULTING FROM ANY
ACTIVITY THAT PASSES FAIRLY CLOSE TO THE NORTHERN MOST TAF
SITES...KAFW/KDFW/KDAL. 75
&&
.UPDATE...
12Z FWD SOUNDING SHOWS MOISTURE DEPTH HAS BEEN REDUCED AS COMPARED
TO YESTERDAY...WHICH SHOULD CAUSE DEWPOINTS TO MIX OUT INTO THE
LOW 60S WEST TO MID 60S CENTRAL AND EAST. IN ADDITION...THE LOW
LEVEL THERMAL PROFILE HAS WARMED A FEW DEGREES OVER YESTERDAY
WHICH MEANS HIGH TEMPS WILL BE A COUPLE DEGREES WARMER TODAY FOR
MOST AREAS. LIGHT ECHOES IN THE SOUTHWEST CWA THIS MORNING ARE
ASSOCIATED WITH WEAK MID LEVEL CONVECTION AND PRECIP IS LIKELY NOT
REACHING THE GROUND. PREVIOUS FORECAST WAS GENERALLY ON TRACK AND
A JUST A FEW CHANGES TO HOURLY GRIDS WERE MADE FOR TRENDS.
CONCERNING THE CONVECTIVE POTENTIAL FOR THIS AFTERNOON AND
EVENING...IT STILL APPEARS THE WESTERN AND NORTHWESTERN COUNTIES
HAVE SOME THREAT OF SEVERE STORMS BUT THERE ARE SOME MIXED
SIGNALS IN THE DATA TODAY. THE STRONG CAP WILL CONTINUE TO BE THE
PRIMARY IMPEDANCE FOR CONVECTIVE ACTIVITY. A LOWER MOISTURE DEPTH
MAY RESULT IN DEWPOINTS MIXING OUT MORE THAN FORECAST WHICH WOULD
KEEP CIN VALUES TOO HIGH. THE DRYLINE WILL ALSO BE POSITIONED
FARTHER WEST TODAY AND ALONG A LINE FROM VERNON TO SAN ANGELO.
HOWEVER...THE MODEL DATA IS IN AGREEMENT THAT A WEAK SHORTWAVE
WILL MOVE ACROSS THE NORTHWEST ZONES THIS EVENING AND RESULT IN
HEIGHT FALLS. THIS BIT OF FORCING WOULD HELP TO ERODE THE CAP AND
WOULD FAVOR CONVECTIVE INITIATION OCCURRING TO THE WEST OF THE CWA
LATE THIS AFTERNOON. MID LEVEL WESTERLY WIND FIELDS ARE SLIGHTLY
STRONGER TODAY AND STORMS WOULD HAVE THE POTENTIAL TO MOVE MORE
EASTERLY AND INTO THE WESTERN CWA BY EARLY THIS EVENING. THE RUC
KEEPS ALL ACTIVITY TO OUR WEST...BUT THE HRRR AND 12Z NAM ARE
BRINGING IT INTO THE WESTERN ZONES. SOME OF THE OTHER HI-RES
MODELS ARE NOT EVEN INITIATING...SO AGAIN POPS WILL BE GENERALLY
JUST 20 PERCENT WEST OF A GAINESVILLE TO MINERAL WELLS TO
GOLDTHWAITE DUE TO INITIATION AND STORM MOTION UNCERTAINTIES. DUE
TO STEEP LAPSE RATES...INSTABILITY WILL BE HIGH WITH CAPES LIKELY
OVER 3000 J/KG AT PEAK HEATING...AND THE MAIN SEVERE THREAT IN OUR
CWA WILL BE LARGE HAIL. ACROSS THE CENTRAL AND EASTERN ZONES THE
CAP WILL REMAIN TOO STRONG FOR SURFACE BASED CONVECTION...BUT
THESE AREAS MAY EXPERIENCE SPRINKLES AND GUSTY WINDS FROM STORM
ANVILS LATER THIS EVENING.
TR.92
&&
.SHORT TERM...
A SHORTWAVE DISTURBANCE WAS SEEN VIA WATER VAPOR SATELLITE IMAGERY
EARLY THIS MORNING ROTATING THROUGH CENTRAL/EASTERN NEW MEXICO.
THIS FEATURE WILL EJECT WITHIN INCREASING SOUTHWEST FLOW ALOFT
ACROSS WEST TX/OK BY AFTERNOON. THIS WILL DEEPEN AND MOVE THE
SURFACE DRYLINE INTO THE SOUTH PLAINS BY EARLY EVENING. LIFT FROM
BOTH OF THESE FEATURES WILL COMBINE WITH HIGH TEMPERATURES AROUND
100 DEGREES AND THE RESULTING VERY HIGH INSTABILITY FOR THE
DEVELOPMENT OF A FEW SUPERCELLS LATE IN THE DAY. THIS IS TYPICALLY
THE TIME OF THE YEAR/MID MAY-LATE JUNE/ THAT THE DRYLINE OUT WEST IS
THE MOST ACTIVE...USUALLY PRODUCING DIURNAL SEVERE WEATHER IN THE
LATE AFTERNOONS AND EARLY EVENINGS. EXPECT MORE DISCRETE SUPERCELLS
LATE TODAY AND THIS EVENING IN AND NEAR OUR FAR WESTERN COUNTIES.
CURRENT SHEAR AND BUNKERS METHOD INDICATE THERE WILL BE MORE
STEERING CURRENTS TO THE NORTHEAST VERSUS YESTERDAY WITH UPPER
TROUGH APPROACHING. HOWEVER...AS WITH ANY SUPERCELL DEVIANT
MOTIONS CANNOT BE RULED OUT ONCE ANY MESOCYCLONES DEVELOP WITHIN
THE STORMS THEMSELVES. DESPITE RELATIVELY HIGH LCLS WITH THE HOT
AND UNSTABLE AIRMASS...JUST ABOUT ALL TYPES OF SEVERE WEATHER WILL
BE POSSIBLE WITH THIS ACTIVITY. EXPECT ABOUT 20-30 PERCENT COVERAGE
OF SEVERE STORMS ACROSS THE NORTHWEST COUNTIES. THE INVERSION
STRENGTHENS ONCE AGAIN BY LATE EVENING AND EXPECT THE MAJORITY OF
ACTIVITY TO DIMINISH QUICKLY.
THE NEXT ROUND OF SEVERE WEATHER LATE SUNDAY WILL LIKELY BE MORE
ACROSS THE NORTHERN TIER COUNTIES VERSUS JUST THE WEST...AS A
NEGATIVE TILT SHORTWAVE DISTURBANCE ROTATES ACROSS THE TX/OK
PANHANDLES INTO WESTERN OK/KS. THE SURFACE DRYLINE WILL HAVE A
BETTER PUSH TO EAST ACROSS THOSE AREAS NORTH OF I-20 IN RESPONSE
TO THIS SHORTWAVE. THE HIGHER COVERAGE OF SEVERE WEATHER AND RISK
WILL BE OVER EASTERN OK INTO THE OZARKS...BUT SHOULD ZIPPER A FEW
STORMS SOUTH-SOUTHWEST ACROSS THE RED RIVER BY EVENING. ALL THREATS
WILL BE POSSIBLE ONCE AGAIN.
&&
.CLIMATE...
YESTERDAY (MAY 17) WAS THE FIRST 90-DEGREE DAY AT DFW AIRPORT THIS
YEAR. IT WAS ALSO THE FIRST TIME NORTH TEXAS HAS SEEN 100 DEGREES
IN 2013. GRAHAM HIT 101...AND BRECKENRIDGE PEAKED AT 104.
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 93 73 92 72 91 / 5 5 10 20 10
WACO, TX 92 71 91 73 90 / 5 5 10 10 10
PARIS, TX 88 70 87 68 87 / 5 5 5 20 10
DENTON, TX 93 72 90 72 90 / 5 10 10 20 10
MCKINNEY, TX 90 72 89 71 88 / 5 5 5 20 10
DALLAS, TX 93 73 91 74 91 / 5 5 10 20 10
TERRELL, TX 90 71 90 71 89 / 5 5 5 10 10
CORSICANA, TX 91 71 89 73 90 / 5 5 5 10 10
TEMPLE, TX 92 71 91 72 90 / 5 5 10 10 10
MINERAL WELLS, TX 96 70 94 69 95 / 5 20 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1256 PM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT MAY 18 2013
UPPER LEVEL RIDGING TAKING PLACE ACROSS THE UPPER MIDWEST TODAY AS
THE WESTERN CONUS TROUGH DEEPENS. PLENTY OF CONVECTION FIRING UP OFF
THE 850 MB LLJ IN CONJUNCTION WITH A PASSING SHORTWAVE ACROSS
CENTRAL MINNESOTA BACK INTO THE DAKOTAS. THIS ACTIVITY WILL MOSTLY
REMAIN NORTH/NORTHWEST OF THE FORECAST AREA...HOWEVER COULD CLIP
PORTIONS OF NORTH CENTRAL WISCONSIN BY MID TO LATE MORNING. LATEST
RUNS OF THE HRRR AND RAP SHOW CONVECTION WANING BUT POSSIBLY
IMPACTING TAYLOR AND CLARK COUNTIES IN WISCONSIN SO HAVE MAINTAINED
SHOWER/STORM CHANCES THERE. MOIST EASTERLY FLOW AND DECAYING
CIRRUS WILL KEEP SKIES MOSTLY CLOUDY TO OVERCAST THIS
MORNING...BUT AS THE MCS LIFTS NORTH...IT WILL PULL THE WARM FRONT
THROUGH THE AREA. PARTLY TO MOSTLY SUNNY SKIES WILL MOST LIKELY BE
SEEN ACROSS NORTHEAST IOWA WHERE THE FRONT IS ABLE TO CLEAR
THROUGH THE MOST.
DECENT INSTABILITY EXPECTED TODAY IN THE WARM SECTOR...AND MUCAPE
VALUES RANGE FROM 1000 TO 2000 J/KG IN A WEAKLY CAPPED ENVIRONMENT.
LACK OF SURFACE CONVERGENCE HOWEVER PRECLUDES HIGHER PRECIPITATION
CHANCES BUT MOST OF THE DETERMINISTIC AND PROBABILISTIC GUIDANCE
HINTS THAT CENTRAL WISCONSIN COULD SEE A STRAY SHOWER OR
THUNDERSTORM THIS AFTERNOON. HAVE MAINTAINED PRECIPITATION CHANCES
THERE. OTHERWISE...A WARM DAY ON TAP WITH LOWER TO MID 80S EXPECTED
SOUTH OF I-94.
RELATIVELY QUIET CONDITIONS TONIGHT AS CONVECTION IS EXPECTED TO
REMAIN WELL TO THE WEST AND NORTH. MILD NIGHT WITH SOUTHERLY
FLOW...AND OVERNIGHT LOWS IN THE UPPER 50S TO LOWER 60S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT MAY 18 2013
FOCUS IS ON SEVERE WEATHER CHANCES SUNDAY AND MONDAY AS ACTIVE
WEATHER PATTERN SETS UP ACROSS MUCH OF THE CENTRAL PLAINS.
UPPER LEVEL NEGATIVE TILTED SHORTWAVE TROUGH EJECTS INTO THE CENTRAL
PLAINS ON SUNDAY...MEANWHILE AT THE SURFACE A FEW WAVES OF LOW PRESSURE
SHOULD BE DEVELOPING ACROSS OKLAHOMA INTO NEBRASKA. THIS WILL PULL
NORTH AMPLE GULF OF MEXICO MOISTURE...WITH PWATS INCREASING FROM
AROUND 1 INCH...TO NEARLY 1.75 INCHES...OR 175 PERCENT OF NORMAL.
SURFACE DEWPOINTS WILL RISE INTO THE LOW TO MIDDLE 60S. THERE SHOULD
BE CONVECTION ACROSS WESTERN IOWA INTO SOUTHWEST MINNESOTA EARLY
SUNDAY MORNING...WHICH WILL BE FEEDING OFF THE 850 MB LLJ. THIS
SHOULD WEAKEN AS IT APPROACHES THE WESTERN FORECAST AREA BUT GOOD
CONSENSUS THAT SHOWERS AND THUNDERSTORMS WILL BE AROUND IN THE
MORNING HOURS. THEN...THE BIG QUESTION BECOMES HOW MUCH CLEARING
WE WOULD SEE TO AID IN DESTABILIZATION. ASSUMING WE CLEAR
OUT...0-3KM MUCAPE IS EXPECTED TO INCREASE TO 1500-2000
J/KG...HIGHEST TO THE SOUTH AND WEST. OVERALL THE SHEAR PROFILES
ARE LESS IMPRESSIVE...BUT STILL SHOW 0-3KM BULK SHEAR OF NEARLY 30
KTS. THE ATMOSPHERE DOES REMAIN UNCAPPED SO EXPECTING GOOD CHANCES
OF CONVECTIVE INITIATION WITH ORGANIZED STORMS IN THE FORM OF
SUPERCELLS OR POSSIBLY BOWING SEGMENTS. STRONG TO SEVERE STORMS
WOULD DEVELOP ACROSS WESTERN INTO CENTRAL IOWA...AND TRACK
EAST/NORTHEAST THROUGH THE EVENING HOURS. THE PRIMARY THREATS ARE
LARGE HAIL AND DAMAGING WINDS. THE ENVIRONMENT STILL SUPPORTS AN
ISOLATED TORNADO...HOWEVER DEPENDING WHERE A WARM FRONT LAYS IS
MORE UNCERTAIN. 18.00Z GFS HAS THIS BOUNDARY ACROSS CENTRAL
IOWA...BUT 18.00Z ECMWF/NAM HINT THIS COULD BE FURTHER SOUTH.
THE WHOLE SYSTEM EDGES EASTWARD MONDAY...WITH THE BOTH THE
SURFACE AND UPPER LEVEL LOW BECOMING STACKED NEAR SIOUX FALLS SD
BY 12Z MONDAY. PIECES OF ENERGY WILL BE ROTATING THROUGH SOUTHERN
BEND OF THIS TROUGH...LIFTING THROUGH THE AREA DURING THE DAY. THE
SYNOPTIC SETUP IS SLIGHTLY MORE FAVORABLE FOR SEVERE WEATHER FOR
PARTS OF THE AREA. THE SHEAR PROFILES ARE MORE IMPRESSIVE WITH
0-6KM BULK SHEAR VALUES 40 TO 50 KTS ACROSS EASTERN IOWA INTO
SOUTHERN WISCONSIN. THE MORE LIMITING FACTOR THIS DAY IS HOW MUCH
DESTABILIZATION WILL OCCUR. THERE COULD BE SCATTERED SHOWERS AND
PLENTY OF CLOUDS AROUND TO LIMIT INSTABILITY. IF WE CAN BREAK OUT
AND FULLY DESTABILIZE...THEN 0-3KM MUCAPE MAY REACH 1500 TO 2000
J/KG. THE ENVIRONMENT SHOULD SUPPORT DISCRETE STORM CELLS...WITH
THE THREATS AGAIN LARGE HAIL AND DAMAGING WINDS.
TUESDAY AND BEYOND...THE UPPER LOW REMAINS NEARLY STATIONARY ACROSS
THE UPPER MIDWEST. THIS GIVES PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS ACROSS THE ENTIRE AREA TUESDAY-THURSDAY. MODEL
CONSENSUS PAINTS 30 TO 60 PERCENT CHANCES WHICH IS APPROPRIATE AT
THIS TIME. FEEL THAT MUCH OF NEXT WEEK COULD BE UNSETTLED BUT SEE
LITTLE OPPORTUNITY TO PROVIDE MORE DETAILS IN WHAT PERIODS WOULD BE
MORE ACTIVE...SINCE TIMING PIECES OF ROTATING AROUND THE UPPER LOW
IS DIFFICULT THIS FAR OUT. THE BIGGER STORY WOULD BE THE HEIGHTENED
RISK FOR EXCESSIVE RAINFALL AND LOCALIZED FLOODING IF REPEATED
ROUNDS OF CONVECTION DO IMPACT THE AREA. BY MID-WEEK...SOILS WOULD
BECOME EVEN MORE SATURATED...AND FLASH GUIDANCE FURTHER REDUCED. SEE
HYDROLOGY SECTION BELOW FOR MORE DETAILS ON THAT RISK.
TEMPERATURE-WISE...WARMEST DAYS LOOK TO BE SUNDAY AND MONDAY BEFORE
A GRADUAL COOL DOWN TUESDAY...THEN TO BELOW NORMAL READINGS
WEDNESDAY THROUGH THURSDAY AS THE UPPER LOW DRIFTS OVERHEAD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1256 PM CDT SAT MAY 18 2013
A MOIST AIRMASS FLOWING INTO THE REGION THIS AFTERNOON WILL
PRODUCE SCATTERED TO BROKEN CUMULUS CLOUDS WITH BASES IN THE 2500
TO 3500 FT RANGE. SOUTH WINDS WILL INCREASE THIS AFTERNOON TO
AROUND 10 KTS AT KLSE AND TO AROUND 14 KTS AT KRST. CANNOT RULE
OUT AN ISOLATED SHOWER OR THUNDERSTORM THIS AFTERNOON...BUT THIS
LOOKS UNLIKELY GIVEN THE LACK OF FORCING. CHANCES FOR SHOWERS AND
STORMS INCREASE ACROSS THE REGION ON SUNDAY AS A LOW PRESSURE
SYSTEM DEEPENS OVER THE NORTHERN PLAINS. AT THIS TIME...THE
HIGHEST CHANCES FOR SHOWERS AND POSSIBLY A THUNDERSTORM APPEARS TO
BE AT KRST IN THE 10 TO 14Z TIMEFRAME...THEN ACROSS MUCH OF THE
AREA LATE SUNDAY AFTERNOON INTO SUNDAY EVENING. THE STORMS COULD
PRODUCE PERIODS OF HEAVY RAIN...GUSTY WINDS AND HAIL...ESPECIALLY
DURING THE LATE AFTERNOON AND EVENING ON SUNDAY.
&&
.HYDROLOGY...SUNDAY AND INTO NEXT WEEK
ISSUED AT 400 AM CDT SAT MAY 18 2013
HEAVY RAINFALL /2 TO 2.5 INCHES/ FELL FRIDAY ACROSS PORTIONS OF
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...AND COMBINED WITH A RECORD
WET METEOROLOGICAL SPRING...RESULTS IN AN INCREASED RISK FOR
LOCALIZED FLASH FLOODING AS WE HEAD INTO THE LATTER PART OF THE
WEEKEND AND MUCH OF NEXT WEEK. PERIODS OF SHOWERS AND THUNDERSTORMS
LOOK TO IMPACT MUCH OF SOUTHEAST MINNESOTA AND NORTHEAST BEGINNING
SUNDAY AFTERNOON. AN ADDITIONAL 1 TO 3 INCHES IS POSSIBLE...AND IF
THIS FALLS IN A SHORT PERIOD...LOCALIZED FLASH FLOODING WOULD OCCUR.
THE 1 AND 3 HOUR FLASH GUIDANCE REMAINS WELL BELOW NORMAL...AND IS
GENERALLY LESS THAN 1 AND 2 INCHES...RESPECTIVELY. WPC CONTINUES THE
SLIGHT RISK OF EXCESSIVE RAINFALL AND FLASH FLOODING EARLY NEXT WEEK
ACROSS MUCH OF CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. A FLASH
FLOOD WATCH MAY BE NECESSARY FOR PORTIONS OF THE AREA.
STREAMS...CREEKS...AND RIVERS HAVE RESPONDED TO THE RECENT
RAINFALL...MOSTLY WITHIN BANK RISES. HOWEVER...REPEATED ROUNDS OF
HEAVY RAIN COULD PUSH SOME OF THE MORE FLASHY BASINS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA TO NEAR FLOOD STAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...WETENKAMP
HYDROLOGY...ZT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1148 AM CDT SAT MAY 18 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
MORE AMPLIFIED PATTERN THIS PERIOD AS WESTERN TROF DIGS SOUTHEAST
AND CUTS OFF OVER THE CENTRAL PLAINS. BUILDING HEIGHTS OVER STATE
TODAY AS RIDGE MOVES EAST ACROSS STATE THIS PERIOD WILL LEAD TO
LESSENING CHANCE OF PCPN TODAY. LOCAL RADARS CURRENTLY SHOWING
ISOLD TO SCATTERED SHOWERS OVER NORTHERN WI. TO THE WEST...AREA OF
THUNDERSTORMS MOVING THROUGH MN AND FAR WESTERN WI NORTH OF
STATIONARY/WARM FRONT AND AHEAD OF VORT EJECTING OUT OF UPPER
TROF. MOST TEMPERATURES REMAIN IN THE LOWER 50S AT THIS TIME GIVEN
CLOUDS AND EAST FLOW.
AGAIN...FOCUS OF FORECAST ON PCPN CHANCES AND TEMPS. SHOWERS OVER
NORTHERN WI NORTH OF 850H BAROCLINC ZONE...AREA OF SIG WAA. HAVE
TRENDED TOWARDS A BLEND OF NAM AND EC...AND MESO HRRR MODELS. ALL
SUGGEST PCPN TO SHIFT NORTH THIS MORNING...LEAVING MUCH OF CWA DRY
THIS AFTERNOON. HAVE KEPT A BUFFER OF CHANCE POPS OVER WEST.
RIDGE AXIS PASSES OVERHEAD TONIGHT. HAVE STAYED WITH DRY FORECAST.
ON SUNDAY...PCPN CHANCES INCREASE THROUGH THE DAY AS RIDGE TO BE
EAST OF STATE AND DYNAMICS WITH UPPER TROF COME IN TO PLAY.
STRENGTHENING LLVL FLOW (30 TO 35 KTS AT 850) STRAIGHT OUT OF GULF
TO BRING PW VALUES TO 1.5 INCHES OR GREATER. INSTABILITY INCREASES
WITH MID LEVEL LAPSE RATES AT 7. EC SUGGESTS CAPE VALUES AROUND
1K...NAM SHOWING NORMAL HIGH BIAS. THOUGH MODEL SOUNDINGS SHOW
STRONG CIN OVER EAST THROUGH DAY. HAVE STAYED DRY EAST THROUGH THE AFTN.
TEMPS TO BE A HEADACHE AGAIN TODAY WITH CLOUDS...ONGOING PCPN AND
EAST FLOW OFF LAKE. DID NOT STRAY TOO FAR FROM PREVIOUS FORECAST.
WENT A BIT HIGHER ON CLOUDS GIVEN PLENTY OF CIRRUS FLOWING THIS
WAY FROM UPSTREAM CONVECTION. STAYED WITH TEMPS HITTING 80 ON SUN
AS BEST PERFORMING GUIDANCE SUGGESTS...THOUGH UNCERTAINTY SIG
GIVEN POSSIBLE CONVECTION.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
PRECIPITATION CHANCES FOR MUCH OF THE UPCOMING WEEK ARE THE MAIN
CONCERNS DURING THIS PART OF THE FORECAST.
THUNDERSTORMS LOOK LIKE A PRETTY GOOD BET ACROSS THE AREA ON
SUNDAY NIGHT WITH SHORT WAVE ENERGY PASSING THROUGH...AN
APPROACHING SURFACE LOW AND A FRONTAL BOUNDARY MOVING NORTHEAST
ACROSS THE AREA. THOUGH EASTERLY COMPONENT OF SURFACE FLOW OFF
LAKE MICHIGAN MAY LESSEN THE CHANCES FOR STORMS IN THE EAST.
HAVE LIKELY POPS FOR MONDAY AND MONDAY NIGHT. SPC DAY 3 OUTLOOK
HAD CENTRAL AND EAST CENTRAL WISCONSIN IN SLIGHT RISK AS A SURFACE
LOW APPROACHES AND A CLOSED 500MB CYCLONE MAKES ITS WAY TOWARD THE
STATE. STILL QUITE A BIT OF UNCERTAINTY REGARDING THIS SEVERE
THREAT.
THE SURFACE LOW SHOULD MAKE ITS WAY INTO WESTERN WISCONSIN ON
TUESDAY AS BOTH THE SURFACE AND UPPER LEVEL SYSTEMS MAKE THEIR WAY
ACROSS THE WESTERN GREAT LAKES REGION. THUNDER CHANCES SHOULD
DIMINISH AS THE SYSTEMS PASS EAST OF THE FORECAST AREA AND THE
CHANCE OF SHOWERS SHOULD FINALLY COME TO AN END BY THE END OF THE
WORK WEEK.
TEMPERATURES AT THE START OF THE PERIOD ARE EXPECTED TO BE ABOVE
NORMAL BUT COOLER TEMPERATURES ARE FORECAST FOR THE REST OF THE
WEEK...WITH HIGHS MAINLY IN THE 60S EACH DAY.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1148 AM CDT SAT MAY 18 2013
WEAKENING BAND OF LIGHT SHOWERS CONTS TO LINGER FROM
NORTH-CENTRAL TO WEST-CENTRAL WI THRU THE AFTERNOON. WHILE MOST
CIGS/VSBYS WL REMAIN VFR...THERE ARE SCATTERED POCKETS OF MVFR CIGS
AS LOW-LEVEL MOISTURE STEADILY INCREASES OVER THE REGION. A NEW
ROUND OF SHWRS/TSTMS ARE EXPECTED TO FIRE OVER THE CNTRL CONUS
THIS EVENING...BUT REMAIN TO OUR WEST DURING THE OVRNGT HOURS.
HOWEVER...SOUTH WINDS ALOFT WL CONT TO PUMP WARM/MOIST AIR INTO WI
WITH DEW PTS CLIMBING INTO THE MID 50S. AS WINDS GO LIGHT TNGT...
ANTICIPATE FOG TO DEVELOP WHICH WOULD SEND VSBYS DOWN INTO THE MVFR
CATEGORY. CANNOT RULE OUT A BRIEF IFR CIG AS WELL OVER THE RHI TAF
SITE WHERE MORE RAIN HAS FALLEN OVER THE PAST 12 HOURS. VFR
CONDITIONS SHOULD RETURN AROUND 15Z SUNDAY AS THE MORNING FOG
BURNS OFF. PCPN CHCS TO INCREASE OVER CNTRL WI BY SUNDAY AFTERNOON
AS A WRMFNT STARTS TO LIFT NWD INTO SW WI.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......AK
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1130 AM CDT SAT MAY 18 2013
.UPDATE...
IT IS DIFFICULT TO TRACK THE LOW CLOUDS ON SATELLITE IMAGERY TODAY
DUE TO THE HIGH CLOUDS STREAMING OVER THEM. HOWEVER...THERE IS A
DISCERNIBLE AREA OF LOW CLOUDS...CONFIRMED BY ASOS/AWOS
OBSERVATIONS...FROM MADISON UP TO JUNEAU AND OVER TO WEST BEND THAT
IS SHIFTING NORTH WITH TIME. CUMULUS CLOUDS HAVE RECENTLY DEVELOPED
OVER SOUTH CENTRAL WI IN AREAS WHERE THE DEWPOINTS ARE ABOUT 59F AND
HIGHER.
THIS HELPS TO DISTINGUISH THE BOUNDARY BETWEEN LAKE-INFLUENCED DRIER
AIR WITH EASTERLY WINDS AND THE STREAM OF MOISTURE FEEDING INTO
SOUTH CENTRAL WI ON SOUTHERLY WINDS. EXPECTING THIS MOIST AIR TO
SPREAD NORTH AND WEST OF MADISON UP TO THE DELLS...BUT NOT SURE
EXACTLY HOW FAR EAST IT WILL GET. IN THE AREA OF CUMULUS
CLOUDS...RAP SOUNDINGS SHOW A SMALL AMOUNT OF CAPE...BUT THE DEPTH
OF THE MOIST LAYER LOOKS VERY SHALLOW. THE 14Z HRRR MODEL NOW BRINGS
LIGHT SHOWERS/TSTORMS BACK INTO AREAS OF SOUTH CENTRAL AND CENTRAL
WI THIS AFTERNOON...SO NOT GIVING UP ON THE SMALL POPS IN OUR
FORECAST.
&&
.AVIATION/18Z TAFS/...
FUEL ALTERNATE CLOUDS...WEAKLY DISCERNIBLE ON VISIBLE SATELLITE
IMAGERY AND CONFIRMED BY ASOS/AWOS OBSERVATIONS FROM MADISON UP TO
JUNEAU AND OVER TO WEST BEND...WILL SHIFT NORTH WITH TIME TODAY.
MVFR CUMULUS CLOUDS HAVE RECENTLY DEVELOPED OVER SOUTH CENTRAL WI IN
AREAS WHERE THE DEWPOINTS ARE ABOUT 59F AND HIGHER.
THIS HELPS TO DISTINGUISH THE BOUNDARY BETWEEN LAKE-INFLUENCED DRIER
AIR WITH EASTERLY WINDS AND THE STREAM OF MOISTURE FEEDING INTO
SOUTH CENTRAL WI ON SOUTHERLY WINDS. EXPECTING THIS MOIST AIR TO
SPREAD NORTH AND WEST OF MADISON UP TO THE DELLS...BUT NOT SURE
EXACTLY HOW FAR EAST IT WILL GET. IN THE AREA OF CUMULUS CLOUDS...
RAP SOUNDINGS SHOW A SMALL AMOUNT OF CAPE...BUT THE DEPTH OF THE
MOIST LAYER LOOKS VERY SHALLOW. THE 14Z HRRR MODEL NOW BRINGS
LIGHT SHOWERS AND ISOLATED TSTORMS BACK INTO AREAS OF SOUTH CENTRAL
AND CENTRAL WI THIS AFTERNOON...SO NOT GIVING UP ON THE SMALL POPS
IN OUR FORECAST. WILL ADD MENTION OF -SHRA BACK INTO MSN TAF.
FOG MAY BE MORE PREVALENT TONIGHT DUE TO LIGHT BOUNDARY LAYER MIXING
BUT TOO MUCH UNCERTAINTY REGARDING CLOUD COVER TO INCLUDE MORE THAN
MVFR VSBYS AT THIS POINT.
&&
.PREV DISCUSSION... /ISSUED 320 AM CDT SAT MAY 18 2013/
AVIATION/12Z TAFS/...BOUNDARY LAYER MIXING AND MOIST LOW TO MID LEVELS
HAS ALLOWED PATCHY LOW CLOUDS TO DEVELOP BY LAKE MI LAST HOUR. WL
LIKELY CONTINUE FOR SEVERAL MORE HOURS AND MAY EXPAND FARTHER
WEST...BUT LOW LEVEL CONVERGENCE WL DIMINISH AS WINDS BEGIN TO
VEER THROUGH THE EARLY MRNG. HENCE WL RETURN TO VFR CONDITIONS BY
MID-MORNING. SOME LIGHT FOG MAY ACCOMPANY LOW CLOUDS BUT BOUNDARY
LAYER MIXING SHOULD PREVENT MORE SIGNIFICANT FOG. FOG MAY BE MORE
PREVALENT TONIGHT DUE TO LIGHT BOUNDARY LAYER MIXING BUT TOO MUCH
UNCERTAINTY REGARDING CLOUD COVER TO INCLUDE MORE THAN MVFR VSBYS
AT THIS POINT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...COLLAR
SUNDAY THROUGH FRIDAY...MBK