Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 05/04/12
AREA FORECAST DISCUSSION
NWS DENVER CO
830 PM MDT THU MAY 3 2012
.UPDATE...A FEW LIGHT SHOWERS ARE MOVING ACROSS EASTERN COLORADO
AT THIS TIME WITH PERHAPS A WEAK THUNDERSTORM OVER NORTHEAST WELD
COUNTY. THESE MAY LINGER FOR A FEW MORE HOURS AND END BY MIDNIGHT.
A BATCH OF MID AND HIGH CLOUDS OVER WESTERN AND CENTRAL COLORADO
WILL MOVE INTO CENTRAL COLORADO. THESE CLOUDS WILL DISSIPATE SOME
AFTER MIDNIGHT LEADING TO MOSTLY CLEAR SKIES. UPDATED THE
FORECAST TO KEEP LOW POPS IN UNTIL MIDNIGHT. OTHERWISE...JUST
MADE MINOR CHANGES TO LINE UP WITH CURRENT CONDITIONS.
&&
.AVIATION...GUSTY SOUTHEAST ELY WINDS WILL WEAKEN AND SHIFT
SOUTHERLY AROUND 06Z. ISOLATED SHOWERS WILL MOVE OFF TO THE EAST
AND END BY 06Z. LIGHT RAIN AND OUTFLOW WINDS TO 30 KNOTS WILL BE
POSSIBLE WITH THE SHOWERS. MAY SEE AN INCREASE IN MID AND HIGH
CLOUDS 05-10Z. LIGHTER WINDS EXPECTED FOR FRIDAY. FORECASTING WIND
DIRECTION WILL BE CHALLENGING FRIDAY DUE TO A POSSIBLE DENVER
CYCLONE.
&&
.PREV DISCUSSION... /ISSUED 544 PM MDT THU MAY 3 2012/
UPDATE...
AVIATION...WITH THE LACK OF ANY INSTABILITY WILL REMOVE THE VCTS
FROM THE LOCAL TERMINALS. WILL STILL KEEP VCSH AS THERE ARE SOME
WEAK HIGH BASED SHOWERS...MAINLY ACROSS BOULDER AND WELD COUNTIES.
STILL SOME STIFF SOUTHEAST WINDS OVER APA AND DEN AND WILL KEEP
THESE GOING THROUGH 02Z THEN GRADUALLY DECREASING AND SHIFTING
MORE SOUTH TO SOUTHWEST.
PREV DISCUSSION... /ISSUED 334 PM MDT THU MAY 3 2012/
SHORT TERM...CUMULUS CONTINUES TO DEVELOP ACROSS MOUNTAINS AND
FOOTHILLS AS WELL AS PORTIONS OF URBAN CORRIDOR. BATCH OF PASSING
CIRRUS SEEMS TO HAVE HALTED FURTHER DEVELOPMENT. RECENT RADAR
LOOPS FINALLY A CELL OVER WEST CENTRAL BOULDER COUNTY. OTHER CELLS
SHOWING UP OVER BOULDER AND SOUTHWEST LARIMER COUNTIES IN THE 1.5
DEGREE SCAN. CURRENT LAPS SURFACE ANALYSIS SHOWING CAPES FROM
100-300 J/KG OVER THE HIGH COUNTRY AS WELL AS IN AND NEAR
FOOTHILLS...LESS FURTHER EAST. STILL CANNOT RULE OUT ADDITIONAL STORMS
DEVELOPING ACROSS THE AREA BY THIS EVENING. THIS THINKING IN LINE
WITH LATEST HRRR AND RUC WHICH SHOW AREA OF CONVECTION MOVING
QUICKLY ACROSS PLAINS DURING THE EVENING...AND LOOKS REASONABLE.
ACARS SOUNDINGS STILL INDICATING AIRMASS A BIT CAPPED...AND FOR
THIS REASON WILL NOT INCREASE POPS. FORECAST SOUNDINGS SHOW
INVERTED-V TYPE SOUNDINGS SO ANY CONVECTION THAT DEVELOPS WILL
PRODUCE MORE WIND THAN RAIN. LATEST NAM STILL MORE UNSTABLE THAT
THE OTHER MODELS DUE TO HIGHER DEW POINTS AND THUS INDICATING MORE
PRECIP. SEEMS A BIT OVERDONE. DRIER SUBSIDENT AIR TO MOVE ACROSS
AREA FROM WEST TO EAST THIS EVENING... SO ANY LINGERING STORMS
OVER FAR NORTHEAST CORNER SHOULD DONE BY MIDNIGHT...WITH SKIES
CLEARING OVERNIGHT. REMOVED ANY MENTION OF FOG FAR NORTHEAST
CORNER LATE TONIGHT AND EARLY FRIDAY BOUNDARY LAYER WIND AND
HUMIDITY PROGS SHOW ANY LINGERING LOW LEVEL MOISTURE EAST OF AREA.
ON FRIDAY A DRIER SOUTHWEST FLOW ALOFT WILL BE OVER AREA WITH
AFTERNOON HUMIDITY REMAINING LOW. WINDS ALOFT NOT ALL THAT STRONG
SO SURFACE WINDS SHOULD REMAIN FAIRLY LIGHT DESPITE ANY MIXING.
NO FIRE WEATHER CONCERNS EXPECTED. TEMPERATURES TO BE A FEW
DEGREES WARMER DUE TO A SLIGHTLY WARMER AIRMASS.
LONG TERM...A MAINLY DRY SOUTHWESTERLY FLOW ALOFT WILL BE OVER
THE CWFA FOR FRIDAY NIGHT AND SATURDAY WITH THE NEXT SYSTEM
MOVING INTO THE NORTHERN ROCKIES BY 00Z SUNDAY. IT WILL REMAIN
WARM AND DRY THROUGH THE DAY SO THE FIRE DANGER WILL REMAIN
ELEVATED BUT THE WINDS STILL LOOK FAIRLY WEAK DURING THE DAY. THE
STRONGEST WINDS THAT DEVELOP ARE NOT EXPECTED TO OCCUR UNTIL THE
PASSAGE OF A COLD FRONT SATURDAY EVENING. MID AND UPPER LEVEL
MOISTURE WILL INCREASE FM THE NORTH AND WEST SATURDAY NIGHT WITH A
COLD FRONT PROGGED TO PUSH THROUGH THE CWFA AT THAT TIME. AS A
RESULT...THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND TSTMS
OVERNIGHT. FOR SUNDAY...A MUCH COOLER AMS WILL BE IN PLACE OVER
THE NORTHEAST PLAINS AS SURFACE HIGH PRESSURE WILL BE FIRMLY IN
CONTROL. TEMPERATURES WILL BE 15-20 DEGREES COOLER THAN SATURDAY.
THE NAM12 FORECAST SOUNDINGS INDICATE A MUCH STRONGER INVERSION
PRESENT AT 700 MB SUNDAY AFTN. THE GFS BUFFER SOUNDINGS STILL SHOW
AN INVERSION BUT NOT AS PRONOUNCED. AS A RESULT...THE BEST CHANCE
OF PCPN WILL LIKELY BE IN AND NEAR THE FRONT RANGE FOOTHILLS. BUT
AT THIS POINT IT LOOKS LIKE SHOWERS VS TSTMS WITH LIMITED
INSTABILITY PRESENT. BY 00Z MONDAY...THE NORTHERN BRANCH THE UPPER
TROUGH WILL BE OVER NORTH DAKOTA WITH THE SRN BRANCH CLOSING OFF
OVER THE CENTRAL CA COAST. SUNDAY NIGHT THE MDLS INDICATE SOME
WEAK MID LEVEL QG ASCENT MOVING ACROSS NORTHERN CO OVERNIGHT. AS A
RESULT...WL CONTINUE WITH CHC/SLGT CHC POPS AT THAT TIME. THE AMS
WILL REMAIN COOL AND UNSETTLED OVER NERN CO THROUGH THE DAY
MONDAY/MONDAY NIGHT. THE FLOW ALOFT APPEARS TO BE WEST/SWLY BUT WITH
LIMITED INSTBY PRESENT. FOR NOW WL CONTINUE WITH A CHC/SLGT CHC OF
SHOWERS/TSTMS. BY TUESDAY...A DRIER NORTHWESTERLY FLOW ALOFT WILL BE
OVER NORTHEASTERN CO. THE SECONDARY BRANCH OF THE TROUGH WILL BE
OVER BAJA CA BY 18Z TUESDAY. IF THIS TREND CONTINUES...THEN THE
CHC OF ANY RAINFALL WILL DECREASE SIGNIFICANTLY OR DIMINISH
ALTOGETHER FOR TUESDAY AND WEDNESDAY. THE TROUGH IS PROGGED TO
SHIFT EAST INTO WESTERN TX BY MIDDAY THURSDAY. IF ITS TRACK SHIFTS
FURTHER NORTH...THEN THE CHANCE OF PCPN WILL INCREASE FM SOUTH TO
NORTH ACROSS THE AREA. THE MDLS DO DIFFER IN TERMS OF THE TIMING
OF THE CLOSED LOW BUT UNFORTUNATELY MOST KEEP IT TOO FAR SOUTH TO
BRING ANY BENEFICIAL PCPN TO THE CWFA AT THIS POINT.
AVIATION...SOUTHEAST WINDS CONTINUE ACROSS AREA AIRPORTS WITH
SOME GUSTS TO 25 KTS...SHOULD CONTINUE THROUGH 02Z. SOME HIGH
BASED SHOWERS AND STORMS BEGINNING TO DEVELOP ACROSS FOOTHILLS.
STILL A SLIGHT CHANCE OF A HIGH BASED THUNDERSTORM THROUGH 02Z
WITH GUSTY OUTFLOW WINDS TO 50 MPH POSSIBLE. WINDS TO WEAKEN AND
SHIFT TO THE SOUTHWEST BY 04Z AS DRAINAGE FLOW DEVELOPS...THEN
SHIFT TO THE NORTHWEST BY 18Z. VFR TO CONTINUE.
HYDROLOGY...SOME SHOWERS AND THUNDERSTORMS POSSIBLE THIS EVENING
WHICH WILL PRODUCE MORE WIND THAN RAIN. ACTIVITY TO MOVE FAIRLY
QUICKLY WHICH WILL LIMIT THE RAINFALL TO AROUND A TENTH OF AN
INCH. DRY CONDITIONS TO PREVAIL FRIDAY.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....COOPER
AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
544 PM MDT THU MAY 3 2012
.UPDATE...
&&
.AVIATION...WITH THE LACK OF ANY INSTABILITY WILL REMOVE THE VCTS
FROM THE LOCAL TERMINALS. WILL STILL KEEP VCSH AS THERE ARE SOME
WEAK HIGH BASED SHOWERS...MAINLY ACROSS BOULDER AND WELD COUNTIES.
STILL SOME STIFF SOUTHEAST WINDS OVER APA AND DEN AND WILL KEEP
THESE GOING THROUGH 02Z THEN GRADUALLY DECREASING AND SHIFTING
MORE SOUTH TO SOUTHWEST.
&&
.PREV DISCUSSION... /ISSUED 334 PM MDT THU MAY 3 2012/
SHORT TERM...CUMULUS CONTINUES TO DEVELOP ACROSS MOUNTAINS AND
FOOTHILLS AS WELL AS PORTIONS OF URBAN CORRIDOR. BATCH OF PASSING
CIRRUS SEEMS TO HAVE HALTED FURTHER DEVELOPMENT. RECENT RADAR
LOOPS FINALLY A CELL OVER WEST CENTRAL BOULDER COUNTY. OTHER CELLS
SHOWING UP OVER BOULDER AND SOUTHWEST LARIMER COUNTIES IN THE 1.5
DEGREE SCAN. CURRENT LAPS SURFACE ANALYSIS SHOWING CAPES FROM
100-300 J/KG OVER THE HIGH COUNTRY AS WELL AS IN AND NEAR
FOOTHILLS...LESS FURTHER EAST. STILL CANNOT RULE OUT ADDITIONAL STORMS
DEVELOPING ACROSS THE AREA BY THIS EVENING. THIS THINKING IN LINE
WITH LATEST HRR AND RUC WHICH SHOW AREA OF CONVECTION MOVING
QUICKLY ACROSS PLAINS DURING THE EVENING...AND LOOKS REASONABLE.
ACARS SOUNDINGS STILL INDICATING AIRMASS A BIT CAPPED...AND FOR
THIS REASON WILL NOT INCREASE POPS. FORECAST SOUNDINGS SHOW
INVERTED-V TYPE SOUNDINGS SO ANY CONVECTION THAT DEVELOPS WILL
PRODUCE MORE WIND THAN RAIN. LATEST NAM STILL MORE UNSTABLE THAT
THE OTHER MODELS DUE TO HIGHER DEWPOINTS AND THUS INDICATING MORE
PRECIP. SEEMS A BIT OVERDONE. DRIER SUBSIDENT AIR TO MOVE ACROSS
AREA FROM WEST TO EAST THIS EVENING... SO ANY LINGERING STORMS
OVER FAR NORTHEAST CORNER SHOULD DONE BY MIDNIGHT...WITH SKIES
CLEARING OVERNIGHT. REMOVED ANY MENTION OF FOG FAR NORTHEAST
CORNER LATE TONIGHT AND EARLY FRIDAY BOUNDARY LAYER WIND AND
HUMIDITY PROGS SHOW ANY LINGERING LOW LEVEL MOISTURE EAST OF AREA.
ON FRIDAY A DRIER SOUTHWEST FLOW ALOFT WILL BE OVER AREA WITH
AFTERNOON HUMIDITY REMAINING LOW. WINDS ALOFT NOT ALL THAT STRONG
SO SURFACE WINDS SHOULD REMAIN FAIRLY LIGHT DESPITE ANY MIXING.
NO FIRE WEATHER CONCERNS EXPECTED. TEMPERATURES TO BE A FEW
DEGREES WARMER DUE TO A SLIGHTLY WARMER AIRMASS.
LONG TERM...A MAINLY DRY SOUTHWESTERLY FLOW ALOFT WILL BE OVER
THE CWFA FOR FRIDAY NIGHT AND SATURDAY WITH THE NEXT SYSTEM
MOVING INTO THE NORTHERN ROCKIES BY 00Z SUNDAY. IT WILL REMAIN
WARM AND DRY THROUGH THE DAY SO THE FIRE DANGER WILL REMAIN
ELEVATED BUT THE WINDS STILL LOOK FAIRLY WEAK DURING THE DAY. THE
STRONGEST WINDS THAT DEVELOP ARE NOT EXPECTED TO OCCUR UNTIL THE
PASSAGE OF A COLD FRONT SATURDAY EVENING. MID AND UPPER LEVEL
MOISTURE WILL INCREASE FM THE NORTH AND WEST SATURDAY NIGHT WITH A
COLD FRONT PROGGED TO PUSH THROUGH THE CWFA AT THAT TIME. AS A
RESULT...THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND TSTMS
OVERNIGHT. FOR SUNDAY...A MUCH COOLER AMS WILL BE IN PLACE OVER
THE NORTHEAST PLAINS AS SURFACE HIGH PRESSURE WILL BE FIRMLY IN
CONTROL. TEMPERATURES WILL BE 15-20 DEGREES COOLER THAN SATURDAY.
THE NAM12 FORECAST SOUNDINGS INDICATE A MUCH STRONGER INVERSION
PRESENT AT 700 MB SUNDAY AFTN. THE GFS BUFFER SOUNDINGS STILL SHOW
AN INVERSION BUT NOT AS PRONOUNCED. AS A RESULT...THE BEST CHANCE
OF PCPN WILL LIKELY BE IN AND NEAR THE FRONT RANGE FOOTHILLS. BUT
AT THIS POINT IT LOOKS LIKE SHOWERS VS TSTMS WITH LIMITED
INSTABILITY PRESENT. BY 00Z MONDAY...THE NORTHERN BRANCH THE UPPER
TROUGH WILL BE OVER NORTH DAKOTA WITH THE SRN BRANCH CLOSING OFF
OVER THE CENTRAL CA COAST. SUNDAY NIGHT THE MDLS INDICATE SOME
WEAK MID LEVEL QG ASCENT MOVING ACROSS NORTHERN CO OVERNIGHT. AS A
RESULT...WL CONTINUE WITH CHC/SLGT CHC POPS AT THAT TIME. THE AMS
WILL REMAIN COOL AND UNSETTLED OVER NERN CO THROUGH THE DAY
MONDAY/MONDAY NIGHT. THE FLOW ALOFT APPEARS TO BE WEST/SWLY BUT WITH
LIMITED INSTBY PRESENT. FOR NOW WL CONTINUE WITH A CHC/SLGT CHC OF
SHOWERS/TSTMS. BY TUESDAY...A DRIER NORTHWESTERLY FLOW ALOFT WILL BE
OVER NORTHEASTERN CO. THE SECONDARY BRANCH OF THE TROUGH WILL BE
OVER BAJA CA BY 18Z TUESDAY. IF THIS TREND CONTINUES...THEN THE
CHC OF ANY RAINFALL WILL DECREASE SIGNIFICANTLY OR DIMINISH
ALTOGETHER FOR TUESDAY AND WEDNESDAY. THE TROUGH IS PROGGED TO
SHIFT EAST INTO WESTERN TX BY MIDDAY THURSDAY. IF ITS TRACK SHIFTS
FURTHER NORTH...THEN THE CHANCE OF PCPN WILL INCREASE FM SOUTH TO
NORTH ACROSS THE AREA. THE MDLS DO DIFFER IN TERMS OF THE TIMING
OF THE CLOSED LOW BUT UNFORTUNATELY MOST KEEP IT TOO FAR SOUTH TO
BRING ANY BENEFICIAL PCPN TO THE CWFA AT THIS POINT.
AVIATION...SOUTHEAST WINDS CONTINUE ACROSS AREA AIRPORTS WITH
SOME GUSTS TO 25 KTS...SHOULD CONTINUE THROUGH 02Z. SOME HIGH
BASED SHOWERS AND STORMS BEGINNING TO DEVELOP ACROSS FOOTHILLS.
STILL A SLIGHT CHANCE OF A HIGH BASED THUNDERSTORM THROUGH 02Z
WITH GUSTY OUFLOW WINDS TO 50 MPH POSSIBLE. WINDS TO WEAKEN AND
SHIFT TO THE SOUTHWEST BY 04Z AS DRAINAGE FLOW DEVELOPS...THEN
SHIFT TO THE NORTHWEST BY 18Z. VFR TO CONTINUE.
HYDROLOGY...SOME SHOWERS AND THUNDERSTORMS POSSIBLE THIS EVENING
WHICH WILL PRODUCE MORE WIND THAN RAIN. ACTIVITY TO MOVE FAIRLY
QUICKLY WHICH WILL LIMIT THE RAINFALL TO AROUND A TENTH OF AN
INCH. DRY CONDITIONS TO PREVAIL FRIDAY.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....COOPER
AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS DENVER CO
1017 AM MDT WED MAY 2 2012
.AVIATION...LOOKS LIKE SOUTHEAST WINDS WILL CONTINUE ACROSS APA
AND DEN THROUGH AT LEAST 20Z WITH SOME GUSTS TO 30 KTS. UPCOMING
ISSUANCE WILL REFLECT THE LATEST THINKING. ALL ELSE SEEMS IN ORDER
FOR NOW.
&&
.PREV DISCUSSION... /ISSUED 948 AM MDT WED MAY 2 2012/
UPDATE...SOUTHEAST WINDS HAVE BEEN CRANKING OVER SOUTHERN AND
EASTERN SECTIONS OF DENVER AREA AS WELL AS ALONG PALMER DIVIDE IN
RESPONSE TO LOCAL CYCLONE. WILL INCREASE WINDS IN THIS AREA FOR A
FEW HOURS WITH TREND TOWARD WEST AND NORTHWEST DURING AFTERNOON IN
LINE WITH LATEST RUC. BROAD UPPER TROUGH OVER NORTHERN ROCKIES
WITH SOME INCREASE IN LIFT ACROSS MOUNTAINS THROUGH THE DAY. BEST
CHANCE FOR SHOWERS AND STORMS TO BE ACROSS ZONES 31 AND 33 AND
HAVE INCREASED THE POPS THERE. REST OF FORECASTS LOOK IN ORDER FOR
NOW. LATEST RUC KEEPS SOME TYPE OF BOUNDARY SOUTH AND EAST OF
DENVER THROUGH THE AFTERNOON WHICH COULD BE A FOCUS FOR STORM
DEVELOPMENT. POTENTIAL FOR GUSTY OUTFLOW WITH STORMS.
PRECIPITATION AMOUNTS STILL LOOKING LIGHT WITH NO HYDROLOGIC
ISSUES ANTICIPATED.
AVIATION...SOUTHEAST WINDS CONTINUE TO CRANK AT APA AND DEN IN
RESPONSE TO CYCLONE OVER DENVER. RUC KEEPS THE SOUTHEASTERLY WINDS
THROUGH ABOUT 20Z AT DEN AND APA BEFORE GOING NORTHWEST...WILL
KEEP SOME SORT OF A SOUTHERLY COMPONENT THROUGH ABOUT 20Z.
OTHERWISE CURRENT TAFS STILL SEEM REASONABLE. STILL A SLIGHT
CHANCE FOR HIGH BASED SHOWERS OR STORMS VICINITY OF THE AIRPORTS
WITH GUST OUTFLOW WINDS THE MAIN IMPACT. VCSH SHOULD SUFFICE FOR NOW.
PREV DISCUSSION... /ISSUED 400 AM MDT WED MAY 2 2012/
SHORT TERM...A BROAD UPPER TROUGH WILL BE PASSING OVER THE
NORTHERN ROCKIES TODAY. A JET STREAK ON THE FRONT OF THE TROUGH
CURRENTLY OVER WYOMING WILL MOVE EAST TO PUT COLORADO IN THE RIGHT
EXIT REGION. THIS AREA HAD KEPT ISOLATED THUNDERSTORMS GOING IN
NORTHEASTERN UTAH PAST MIDNIGHT LAST NIGHT. PRECIPITABLE WATER
VALUES ARE EXPECTED TO BE ABOUT THE SAME AS YESTERDAY BUT A LITTLE
MORE INSTABILITY AROUND...BETWEEN 150 AND 300 J/KG OF CAPE.
THEREFORE WILL BE EXPECTING SHOWERS AND THUNDERSTORMS TO BE A
LITTLE MORE WIDESPREAD ACROSS THE FORECAST AREA THIS AFTERNOON AND
EVENING. JUST LIKE YESTERDAY...THE MAIN IMPACT WILL BE GUSTY WINDS
OF UP TO 40 MPH AND LIGHT RAIN AMOUNTS. SLIGHT WARM ADVECTION WILL
BRING MAXIMUM TEMPERATURES A FEW DEGREES WARMER THAN YESTERDAY.
SOME MOISTURE TRANSPORTING IN WILL BRING SLIGHTLY HIGHER DEWPOINTS
AND THEREFORE SHOULD SEE HIGHER HUMIDITIES. A SURFACE TROUGH OVER
THE EASTERN PLAINS STRETCHING UP TO SOUTH DAKOTA WILL BRING
SOUTHERLY WINDS EARLY TODAY...THEN THE TROUGH WILL DEEPEN AND MOVE
OFF EAST WITH A WEAK FRONT MOVING SOUTH DOWN THE COLORADO PLAINS
TURNING WINDS NORTHERLY FOR A SHORT TIME. COULD SEE SOME STRATUS
OR PATCHY FOG AROUND OR EAST OF LIMON TONIGHT....BUT NOT ENOUGH
CONFIDENCE TO PUT IN THE FORECAST. OTHERWISE TONIGHT WILL BE
CALM...CLEAR AND SIMILAR TEMPERATURES TO LAST NIGHT.
LONG TERM...LOW LEVEL MOISTURE WILL INCREASE ACROSS THE PLAINS
THURSDAY WITH EAST/SOUTHEAST BOUNDARY LAYER FLOW ADVECTING IN
HIGHER DEWPOINTS FROM KANSAS. THIS WILL ALLOW A WEAK THETA-E RIDGE
TO DEVELOP ACROSS THE EASTERN PLAINS BY AFTERNOON WITH SURFACE
BASED CAPES NEAR 1000 J/KG. HOWEVER...AT THE SAME TIME THERE IS
VERY LITTLE OR NO SYNOPTIC SCALE LIFT/SHORTWAVE TO HELP DESTABILIZE
THE ATMOSPHERE. THEREFORE SEE LITTLE REASON TO CHANGE THE ONGOING
FORECAST OF LOW POPS FROM THE FRONT RANGE EASTWARD ACROSS THE
PLAINS.
BY FRIDAY...A DEEPER AND DRIER SOUTH/SOUTHWEST FLOW ALOFT WILL
DEVELOP OVER THE FORECAST AREA. THIS WILL PREVENT ANY CONVECTION
FROM DEVELOPING AND ALSO BRING UNSEASONABLY WARM CONDITIONS TO THE
FORECAST AREA. LOOKS LIKE HIGH TEMPS WILL REACH THE MID 80S ACROSS
THE PLAINS. RECORD FOR DENVER IS 87F SET IN 2000 AND WE SHOULD BE
WITHIN A COUPLE DEGREES OF THAT. FIRE DANGER WILL BE ELEVATED WITH
LOW HUMIDITIES AS WELL...BUT ANY EXTENT OF RED FLAG WARNINGS
SHOULD BE LIMITED BY GREEN FUELS OVER THE EASTERN PLAINS AND
LIGHTER WINDS ALONG THE FRONT RANGE. AT THIS TIME...MOST PRONE
AREA IS SHAPING UP TO BE SOUTH PARK WHERE HUMIDITIES DROP TO
AROUND 10 PERCENT WITH GUSTY WINDS POSSIBLE THERE.
FOR THE WEEKEND...A WEAK SURGE IS EXPECTED TO BACK ACROSS THE
PLAINS SATURDAY WITH VERY SLIGHT COOLING BUT AN INCREASE IN
MOISTURE. THIS WOULD LEAD TO A CHANCE OF STRONG THUNDERSTORMS OVER
THE NORTHEAST PLAINS LATE SATURDAY INTO SATURDAY NIGHT. SUNDAY
IS SHAPING UP TO BE COOLER AND MORE MOIST AS THE MAIN COLD FRONT
REACHES THE AREA. THIS SHOULD BRING MORE WIDESPREAD SHOWER AND
THUNDERSTORM COVERAGE BY SUNDAY AFTERNOON AND SUNDAY NIGHT.
SHOWERS AND A FEW THUNDERSTORMS WILL LIKELY REMAIN IN THE AREA
THROUGH THE FIRST HALF OF NEXT WEEK WITH A SLOW MOVING UPPER
TROUGH OVER THE REGION. LAST 3 RUNS OF THE ECMWF HAVE FLIP-FLOPPED
REGARDING WHETHER WE WILL SEE A 4 CORNERS LOW OR JUST A SLOW MOVING
UPPER LEVEL TROUGH...WHILE THE LATEST GFS ENSEMBLES ARE AVERAGING
TOWARD A SLOW MOVING TROUGH. NONETHELESS...EARLY NEXT WEEK SHOULD
FEATURE A MUCH BETTER CHANCE OF MEANINGFUL PRECIPITATION AND BELOW
NORMAL TEMPERATURES.
AVIATION...DRAINAGE WINDS WILL BE SLOWLY TRANSITIONING TO THE
WEST LATE AFTERNOON...WITH A FRONT EXPECTED TO MOVE THROUGH THE
AREA AIRPORTS AFTER 20Z. A SLIGHT CHANCE OF HIGH BASED SHOWERS OR
THUNDERSTORMS NEAR THE AIRPORTS LATE THIS AFTERNOON...MAIN IMPACT
WILL BE GUSTY OUTFLOW WINDS.
HYDROLOGY...A SLIGHT CHANCE OF A SHOWER OR STORM TO MOVE OVER THE
BURN AREA THIS AFTERNOON OR EVENING. MAIN IMPACT WILL BE
WIND...WITH ONLY UP TO A TENTH OF AN INCH OF PRECIPITATION AT
MOST.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER CO
948 AM MDT WED MAY 2 2012
.UPDATE...SOUTHEAST WINDS HAVE BEEN CRANKING OVER SOUTHERN AND
EASTERN SECTIONS OF DENVER AREA AS WELL AS ALONG PALMER DIVIDE IN
RESPONSE TO LOCAL CYCLONE. WILL INCREASE WINDS IN THIS AREA FOR A
FEW HOURS WITH TREND TOWARD WEST AND NORTHWEST DURING AFTERNOON IN
LINE WITH LATEST RUC. BROAD UPPER TROUGH OVER NORTHERN ROCKIES
WITH SOME INCREASE IN LIFT ACROSS MOUNTAINS THROUGH THE DAY. BEST
CHANCE FOR SHOWERS AND STORMS TO BE ACROSS ZONES 31 AND 33 AND
HAVE INCREASED THE POPS THERE. REST OF FORECASTS LOOK IN ORDER FOR
NOW. LATEST RUC KEEPS SOME TYPE OF BOUNDARY SOUTH AND EAST OF
DENVER THROUGH THE AFTERNOON WHICH COULD BE A FOCUS FOR STORM
DEVELOPMENT. POTENTIAL FOR GUSTY OUTFLOW WITH STORMS.
PRECIPITATION AMOUNTS STILL LOOKING LIGHT WITH NO HYDROLOGIC
ISSUES ANTICIPATED.
&&
.AVIATION...SOUTHEAST WINDS CONTINUE TO CRANK AT APA AND DEN IN
RESPONSE TO CYCLONE OVER DENVER. RUC KEEPS THE SOUTHEASTERLY WINDS
THROUGH ABOUT 20Z AT DEN AND APA BEFORE GOING NORTHWEST...WILL
KEEP SOME SORT OF A SOUTHERLY COMPONENT THROUGH ABOUT 20Z.
OTHERWISE CURRENT TAFS STILL SEEM REASONABLE. STILL A SLIGHT
CHANCE FOR HIGH BASED SHOWERS OR STORMS VICINITY OF THE AIRPORTS
WITH GUST OUTFLOW WINDS THE MAIN IMPACT. VCSH SHOULD SUFFICE FOR NOW.
&&
.PREV DISCUSSION... /ISSUED 400 AM MDT WED MAY 2 2012/
SHORT TERM...A BROAD UPPER TROUGH WILL BE PASSING OVER THE
NORTHERN ROCKIES TODAY. A JET STREAK ON THE FRONT OF THE TROUGH
CURRENTLY OVER WYOMING WILL MOVE EAST TO PUT COLORADO IN THE RIGHT
EXIT REGION. THIS AREA HAD KEPT ISOLATED THUNDERSTORMS GOING IN
NORTHEASTERN UTAH PAST MIDNIGHT LAST NIGHT. PRECIPITABLE WATER
VALUES ARE EXPECTED TO BE ABOUT THE SAME AS YESTERDAY BUT A LITTLE
MORE INSTABILITY AROUND...BETWEEN 150 AND 300 J/KG OF CAPE.
THEREFORE WILL BE EXPECTING SHOWERS AND THUNDERSTORMS TO BE A
LITTLE MORE WIDESPREAD ACROSS THE FORECAST AREA THIS AFTERNOON AND
EVENING. JUST LIKE YESTERDAY...THE MAIN IMPACT WILL BE GUSTY WINDS
OF UP TO 40 MPH AND LIGHT RAIN AMOUNTS. SLIGHT WARM ADVECTION WILL
BRING MAXIMUM TEMPERATURES A FEW DEGREES WARMER THAN YESTERDAY.
SOME MOISTURE TRANSPORTING IN WILL BRING SLIGHTLY HIGHER DEWPOINTS
AND THEREFORE SHOULD SEE HIGHER HUMIDITIES. A SURFACE TROUGH OVER
THE EASTERN PLAINS STRETCHING UP TO SOUTH DAKOTA WILL BRING
SOUTHERLY WINDS EARLY TODAY...THEN THE TROUGH WILL DEEPEN AND MOVE
OFF EAST WITH A WEAK FRONT MOVING SOUTH DOWN THE COLORADO PLAINS
TURNING WINDS NORTHERLY FOR A SHORT TIME. COULD SEE SOME STRATUS
OR PATCHY FOG AROUND OR EAST OF LIMON TONIGHT....BUT NOT ENOUGH
CONFIDENCE TO PUT IN THE FORECAST. OTHERWISE TONIGHT WILL BE
CALM...CLEAR AND SIMILAR TEMPERATURES TO LAST NIGHT.
LONG TERM...LOW LEVEL MOISTURE WILL INCREASE ACROSS THE PLAINS
THURSDAY WITH EAST/SOUTHEAST BOUNDARY LAYER FLOW ADVECTING IN
HIGHER DEWPOINTS FROM KANSAS. THIS WILL ALLOW A WEAK THETA-E RIDGE
TO DEVELOP ACROSS THE EASTERN PLAINS BY AFTERNOON WITH SURFACE
BASED CAPES NEAR 1000 J/KG. HOWEVER...AT THE SAME TIME THERE IS
VERY LITTLE OR NO SYNOPTIC SCALE LIFT/SHORTWAVE TO HELP DESTABILIZE
THE ATMOSPHERE. THEREFORE SEE LITTLE REASON TO CHANGE THE ONGOING
FORECAST OF LOW POPS FROM THE FRONT RANGE EASTWARD ACROSS THE
PLAINS.
BY FRIDAY...A DEEPER AND DRIER SOUTH/SOUTHWEST FLOW ALOFT WILL
DEVELOP OVER THE FORECAST AREA. THIS WILL PREVENT ANY CONVECTION
FROM DEVELOPING AND ALSO BRING UNSEASONABLY WARM CONDITIONS TO THE
FORECAST AREA. LOOKS LIKE HIGH TEMPS WILL REACH THE MID 80S ACROSS
THE PLAINS. RECORD FOR DENVER IS 87F SET IN 2000 AND WE SHOULD BE
WITHIN A COUPLE DEGREES OF THAT. FIRE DANGER WILL BE ELEVATED WITH
LOW HUMIDITIES AS WELL...BUT ANY EXTENT OF RED FLAG WARNINGS
SHOULD BE LIMITED BY GREEN FUELS OVER THE EASTERN PLAINS AND
LIGHTER WINDS ALONG THE FRONT RANGE. AT THIS TIME...MOST PRONE
AREA IS SHAPING UP TO BE SOUTH PARK WHERE HUMIDITIES DROP TO
AROUND 10 PERCENT WITH GUSTY WINDS POSSIBLE THERE.
FOR THE WEEKEND...A WEAK SURGE IS EXPECTED TO BACK ACROSS THE
PLAINS SATURDAY WITH VERY SLIGHT COOLING BUT AN INCREASE IN
MOISTURE. THIS WOULD LEAD TO A CHANCE OF STRONG THUNDERSTORMS OVER
THE NORTHEAST PLAINS LATE SATURDAY INTO SATURDAY NIGHT. SUNDAY
IS SHAPING UP TO BE COOLER AND MORE MOIST AS THE MAIN COLD FRONT
REACHES THE AREA. THIS SHOULD BRING MORE WIDESPREAD SHOWER AND
THUNDERSTORM COVERAGE BY SUNDAY AFTERNOON AND SUNDAY NIGHT.
SHOWERS AND A FEW THUNDERSTORMS WILL LIKELY REMAIN IN THE AREA
THROUGH THE FIRST HALF OF NEXT WEEK WITH A SLOW MOVING UPPER
TROUGH OVER THE REGION. LAST 3 RUNS OF THE ECMWF HAVE FLIP-FLOPPED
REGARDING WHETHER WE WILL SEE A 4 CORNERS LOW OR JUST A SLOW MOVING
UPPER LEVEL TROUGH...WHILE THE LATEST GFS ENSEMBLES ARE AVERAGING
TOWARD A SLOW MOVING TROUGH. NONETHELESS...EARLY NEXT WEEK SHOULD
FEATURE A MUCH BETTER CHANCE OF MEANINGFUL PRECIPITATION AND BELOW
NORMAL TEMPERATURES.
AVIATION...DRAINAGE WINDS WILL BE SLOWLY TRANSITIONING TO THE
WEST LATE AFTERNOON...WITH A FRONT EXPECTED TO MOVE THROUGH THE
AREA AIRPORTS AFTER 20Z. A SLIGHT CHANCE OF HIGH BASED SHOWERS OR
THUNDERSTORMS NEAR THE AIRPORTS LATE THIS AFTERNOON...MAIN IMPACT
WILL BE GUSTY OUTFLOW WINDS.
HYDROLOGY...A SLIGHT CHANCE OF A SHOWER OR STORM TO MOVE OVER THE
BURN AREA THIS AFTERNOON OR EVENING. MAIN IMPACT WILL BE
WIND...WITH ONLY UP TO A TENTH OF AN INCH OF PRECIPITATION AT
MOST.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
200 PM EDT WED MAY 2 2012
.SYNOPSIS...
18Z WATER VAPOR AND H4 RUC ANALYSIS CONTINUES TO SHOW A RATHER
UNAMPLIFIED UPPER LEVEL PATTERN ACROSS THE CONUS. NORTHERN STREAM
FLOW SHOWS SLIGHT TROUGHING OVER THE INTER-MOUNTAIN WEST BEFORE
BENDING BACK TO THE NORTH INTO LONGWAVE RIDGING FROM THE GREAT LAKES
TO NEW ENGLAND/QUEBEC. CLOSER TO HOME WE FIND BROAD UPPER LEVEL
RIDGING IN PLACE OVER THE SOUTHEASTERN STATES. 12Z KTBW SOUNDING
PROFILE IS NOT ALL THAT UNFAVORABLE TO SUPPORT DEEP CONVECTION. THE
PW VALUE IS AT 1.5"...WHICH IS ACTUALLY QUITE A BIT ABOVE NORMAL FOR
EARLY MAY. MID-LEVEL THETA-E VALUES ARE NOT ALL THAT IMPRESSIVE...
BUT ALSO NOT COMPLETELY HOSTILE TO DEEP CONVECTION WITH VALUES
RANGING BETWEEN 321-324K.
AT THE SURFACE...FORECAST AREA RESIDES WITHIN A REGION OF LOW LEVEL
SOUTHEASTERLY FLOW ON THE SOUTHERN SIDE OF THE SUBTROPICAL RIDGE
AXIS. GRADIENT IS NOT AS TIGHT AS PREVIOUS DAYS...HOWEVER STILL
EXPERIENCING MODERATE OFFSHORE FLOW THIS AFTERNOON. BIG FORECAST
QUESTION OVER THE NEXT SEVERAL HOURS WILL BE IF DIURNAL HEATING
INLAND WILL BE ENOUGH TO FORCE SEA-BREEZE DEVELOPMENT AND GIVE US A
SHOT AT SCT EARLY EVENING CONVECTION. IF A FEEBLE SEA-BREEZE CAN
DEVELOP LATER THIS AFTERNOON...THE EASTERLY COMPONENT TO THE
SYNOPTIC FLOW WILL CERTAINLY PIN THE CIRCULATION VERY CLOSE TO THE
COAST...WITH LITTLE INLAND PROPAGATION.
&&
.SHORT TERM (REST OF THIS AFTERNOON THROUGH FRIDAY)...
THROUGH EARLY EVENING...AS MENTIONED ABOVE...DIFFICULT FORECAST IN
WHETHER OR NOT A FEEBLE SEABREEZE WILL ESTABLISH ITSELF AT THE COAST
OVER THE NEXT FEW HOURS. LATEST OBSERVATIONS MAKE THIS VERY
QUESTIONABLE WITH 15+ KNOT OFFSHORE GUSTS STILL BEING REPORTED AT
THE COAST. HOWEVER...MOST OF THE GUIDANCE STILL SHOWS THIS FLOW
BREAKING DOWN BY 21Z. ALSO...DUE TO NOT UNFAVORABLE THERMODYNAMICS
IN PLACE...IT IS NO SURPRISE THAT MANY OF THE PARAMETRIZED AND
CONVECTION ALLOWING 12Z GUIDANCE CONTINUE TO SHOWING THE CONVECTIVE
DEVELOPMENT EARLY THIS EVENING. WITH TO THE SEA-BREEZE BEING HELD
CLOSE TO THE COAST...SO WILL THE BEST LOW LEVEL FOCUS FOR ASCENT.
CONVECTION THAT DOES FIRE NEAR THE COAST WILL GENERALLY DRIFT BACK
TO THE WEST/WNW WITH THE DEEP LAYER FLOW...AND THEREFORE HAVE THE
HIGHEST POPS (~40%) ALONG ALL THE COASTAL ZONES...AND THEN TAPER
RAIN CHANCES DOWN AS ONE TRAVELS INLAND. WILL NOT MAKE ANY DRASTIC
CHANGES TO THE FORECAST...BUT WILL PULL THE CHANCES FOR SCT
SHOWER/STORMS EVEN CLOSER TO THE COAST THAN WAS PREVIOUSLY DRAWN.
TONIGHT...LINGERING SHOWERS/STORMS SHOULD PUSH OFFSHORE INTO THE
EASTERN GULF DURING THE MIDDLE/LATER EVENING HOURS. THE REMAINDER OF
THE OVERNIGHT LOOKS QUIET...DRY AND WARM. LOW TEMPERATURES BY
SUNRISE THURSDAY MORNING LOOK TO RANGE FROM THE MIDDLE 60S IN THE
INTERIOR COOL SPOTS TO THE LOWER 70S ALONG THE COAST.
THURSDAY...SHORTWAVE ENERGY IS PROGGED TO BE APPROACHING AL/GA/FL
PANHANDLE DURING THE DAY. THIS SYNOPTIC SUPPORT LOOKS TO REMAIN
REMOVED TO THE NW OF OUR ZONES AND THEREFORE WILL LIKELY BE AN
ENHANCEMENT TO CONVECTIVE POTENTIAL ONLY TO AREA NORTH AND WEST OF
THE FLORIDA BIG BEND. FOR OUR FORECAST AREA...STACKED RIDGING WILL
REMAIN IN CONTROL WITH AN EVEN DRIER COLUMN BUILDING IN FROM THE
EAST. AT THE SURFACE...THE SUBTROPICAL RIDGE AXIS WILL BUILD
SOUTHWARD SOMEWHAT ALLOWING A LIGHTER GRADIENT AND WEAKER SYNOPTIC
EASTERLY FLOW. THIS WEAKER FLOW WILL ALMOST CERTAINLY ALLOW THE
DEVELOPMENT OF WELL-DEFINED SEA-BREEZE CIRCULATIONS DURING THE
AFTERNOON. HOWEVER...THE THERMODYNAMICS BECOME QUITE HOSTILE TO DEEP
CONVECTION WITH MID-LEVEL THETA-E VALUES DROPPING BELOW 320K. NEVER
WANT TO COMPLETELY RULE OUT A CONVECTIVE ELEMENT THAT CAN OVERCOME
THE NEGATIVE FACTORS...BUT FEEL ANY COVERAGE ON THURSDAY WILL BE LOW
ENOUGH TO KEEP MENTION OUT OF THE FORECAST. WILL ONLY DRAW A 10%
SILENT POP IN THE GRIDS. HOT DAY IN THE FORECAST WITH TEMPERATURES
PUSHING THE LOWER 90S INLAND AND IN THE 80S AT THE BEACHES DUE TO
THE DEVELOPING ONSHORE FLOW.
FRIDAY...ANOTHER MAINLY DRY AND WARM DAY TO END OUT THE WORKWEEK.
WEAK RESIDUAL SYNOPTIC ENERGY FROM THE SHORTWAVE CROSSING THE
SOUTHEASTERN STATES WILL MAKE ITS CLOSEST APPROACH TO OUR NORTHERN
ZONES DURING THE DAY AND MAY BE JUST ENOUGH TO FORCE A FEW ISOLATED
SHOWERS. WILL DRAWN IN A SLIGHT CHANCE 15-20% POP FOR AREAS
GENERALLY NORTH OF CRYSTAL RIVER DURING THE AFTERNOON...BUT
ELSEWHERE WILL LEAVE RAIN MENTION OUT OF THE FORECAST AS
THERMODYNAMICS REMAIN QUITE HOSTILE TO DEEP CONVECTION.
&&
.LONG TERM (SATURDAY THROUGH TUESDAY)...
THE GLOBAL MODELS ARE GENERALLY CONSISTENT ALTHOUGH THERE ARE SOME
MINOR DIFFERENCES IN LOCATION...TIMING AND SMALL FEATURES. AN UPPER
RIDGE FROM THE WESTERN GULF TO THE GREAT LAKES WITH A TROUGH OFF THE
EASTERN BOARD DOWN TO THE BAHAMAS AND EASTERN CUBA FRIDAY NIGHT
SLOWLY WORKS EAST. AT THE SURFACE HIGH PRESSURE FROM THE GULF TO THE
ATLANTIC...WITH AN AXIS INITIALLY ACROSS NORTH/CENTRAL FL...SAGS
SOUTHWARD AS A WEAK FRONTAL BOUNDARY MOVES FROM THE SE U.S. COASTAL
WATERS INTO THE STATE MON AND TUE.
WILL KEEP THE CURRENT FORECAST TREND FOR NOW. PARTLY CLOUDY WITH A
SLIGHT CHANCE OF DAYTIME THUNDERSTORMS...MAINLY IN THE AFTERNOONS.
THE FRONTAL BOUNDARY MON/TUE WOULD SUGGEST SLIGHTLY MORE COVERAGE
OF PRECIPITATION. HOWEVER HAVE LIMITED POPS TO JUST SLIGHT CHANCE...
CLOSER TO CLIMO AND BELOW SOME OF THE MEX GUIDANCE. TEMPERATURES
WILL BE NEAR OR JUST ABOVE NORMAL...BY PERHAPS A COUPLE OF DEGREES
AT TIMES. AS THE RIDGE AXIS SHIFTS SOUTH ACROSS THE AREA WINDS WILL
BE LIGHT WITH SEA BREEZE CIRCULATIONS FOR THE AFTERNOONS.
&&
.AVIATION...
MAINLY VFR WITH SOME CHANCE OF ISOLATED TO SCATTERED LATE AFTERNOON
AND EVENING STORMS NEAR COASTAL TERMINALS. COULD ALSO SEE BRIEF MVFR
CEILINGS AGAIN AFTER SUNRISE THURSDAY BUT CONFIDENCE TOO LOW TO PUT
IN TAFS AT THIS TIME.
&&
.MARINE...
NEAR CAUTIONARY LEVEL FLOW WILL CONTINUE OVERNIGHT...ESPECIALLY FROM
TAMPA BAY SOUTHWARD AND THEN DIMINISH QUICKLY ON THURSDAY BELOW
HEADLINE CRITERIA. THE SUBTROPICAL RIDGE AXIS WILL THEN BUILD
SOUTHWARD OVER THE AREA DURING THE LATER PORTION OF THE WEEK AND
HELP KEEP WINDS AND SEAS LOW THROUGH SATURDAY.
&&
.FIRE WEATHER...
NO SIGNIFICANT FIRE WEATHER CONCERNS EXPECTED THROUGH THE REST OF
THE WEEK. RELATIVE HUMIDITY VALUES ARE FORECAST TO BRIEFLY APPROACH
CRITICAL VALUES OVER INTERIOR ZONES THE NEXT SEVERAL
AFTERNOON...HOWEVER CRITICAL DURATIONS OF THESE VALUES ARE NOT
EXPECTED AND LDSI VALUES SHOULD GENERALLY STAY BELOW 75.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 71 89 70 89 / 20 10 5 10
FMY 67 90 67 89 / 10 10 5 10
GIF 67 91 65 91 / 10 10 5 10
SRQ 69 85 69 85 / 20 10 5 10
BKV 67 89 65 89 / 15 10 5 10
SPG 71 85 72 83 / 20 10 5 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1040 AM EDT WED MAY 2 2012
.UPDATE (REST OF TODAY AND TONIGHT)...
14Z WATER VAPOR AND H4 RUC ANALYSIS CONTINUES TO SHOW A RATHER
UNAMPLIFIED UPPER LEVEL PATTERN ACROSS THE CONUS. NORTHERN STREAM
FLOW SHOWS SLIGHT TROUGHING OVER THE INTER-MOUNTAIN WEST BEFORE
BENDING BACK TO THE NORTH INTO LONGWAVE RIDGING FROM THE GREAT LAKES
TO NEW ENGLAND/QUEBEC. ONE SUBTLE SHORTWAVE WITHIN THE FLOW IS NOW
PASSING THROUGH THE UPPER MS VALLEY AND FORCING SEVERAL AREA OF
SHOWERS AND STORMS ACROSS THE GREAT LAKES REGION. CLOSER TO HOME WE
FIND BROAD UPPER LEVEL RIDGING IN PLACE OVER THE SOUTHEASTERN
STATES. 12Z KTBW SOUNDING PROFILE IS NOT ALL THAT UNFAVORABLE TO
SUPPORT DEEP CONVECTION. THE PW VALUE IS AT 1.5"...WHICH IS ACTUALLY
QUITE A BIT ABOVE NORMAL FOR EARLY MAY. MID-LEVEL THETA-E VALUES ARE
NOT ALL THAT IMPRESSIVE...BUT ALSO NOT COMPLETELY HOSTILE TO DEEP
CONVECTION WITH VALUES RANGING BETWEEN 322-325K.
AT THE SURFACE...FORECAST AREA RESIDES WITHIN A REGION OF LOW LEVEL
SOUTHEASTERLY FLOW ON THE SOUTHERN SIDE OF THE SUBTROPICAL RIDGE
AXIS. GRADIENT IS NOT AS TIGHT AS PREVIOUS DAYS...AND WITH GOOD
DIURNAL HEATING INLAND...WE SHOULD BE ABLE TO DEVELOP SEA-BREEZE
CIRCULATION LATE IN THE DAY. THE EASTERLY COMPONENT TO THE SYNOPTIC
FLOW HOWEVER WILL KEEP THESE SEA-BREEZES PINNED CLOSE TO THE
COAST...WITH LITTLE INLAND PROPAGATION.
ALREADY SEEING A QUICK DEVELOPMENT OF TODAY`S CU FIELD...SO A PARTLY
CLOUDY FORECAST WILL GO AHEAD THROUGH THE REMAINDER OF THE DAY. 850
MB TEMPS IN THE 14-16C RANGE SHOULD MIX OUT TO AROUND 90 INLAND BY
LATE AFTERNOON. THE DEVELOPING ONSHORE FLOW WILL HOLD TEMPS DOWN A
FEW DEGREES AT THE BEACHES...HOWEVER THE LATE START TO THE
SEA-BREEZES SHOULD STILL ALLOW TEMPS TO REACH THE MID/UPPER 80S. DUE
TO NOT UNFAVORABLE THERMODYNAMICS IN PLACE...IT IS NO SURPRISE THAT
MANY OF THE PARAMETRIZED AND CONVECTION ALLOWING GUIDANCE ARE
SHOWING SCT SHOWER/STORMS DEVELOPMENT ALONG THE SEA-BREEZE LATE THIS
AFTERNOON/ EARLY EVENING. AS MENTIONED ABOVE...THE SEA-BREEZE WILL
BE HELD CLOSE TO THE COAST AND HENCE SO WILL THE BEST LOW LEVEL
FOCUS FOR ASCENT. CONVECTION THAT DOES FIRE NEAR THE COAST WILL
GENERALLY DRIFT BACK TO THE WEST/WNW WITH THE DEEP LAYER FLOW...AND
THEREFORE HAVE THE HIGHEST POPS (~40%) ALONG ALL THE COASTAL
ZONES...AND THEN TAPER RAIN CHANCES DOWN AS ONE TRAVELS INLAND. THIS
REPRESENTS AN INCREASE IN THE RAIN CHANCES ALONG THE NATURE COAST
ZONES FROM THE EARLIER FORECAST.
LINGERING SHOWERS/STORMS SHOULD PUSH OFFSHORE INTO THE EASTERN GULF
DURING THE MIDDLE/LATER EVENING HOURS. THE REMAINDER OF THE
OVERNIGHT LOOKS QUIET...DRY AND WARM. LOW TEMPERATURES BY SUNRISE
THURSDAY MORNING LOOK TO RANGE FROM THE MIDDLE 60S IN THE INTERIOR
COOL SPOTS TO THE LOWER 70S ALONG THE COAST. HAVE A GREAT DAY!
&&
.AVIATION...
VFR WITH SOME BRIEF MVFR CEILINGS THIS MORNING...THEN SEA BREEZE
SHOWERS AND THUNDERSTORMS MAINLY AFTER 18Z.
&&
.MARINE...
ELEVATED WINDS AND SEAS WILL DIMINISH VERY EARLY IN THE PERIOD AS
THE SMALL CRAFT ADVISORY COMES TO AN END. SURFACE LOW PRESSURE
WILL PUSH WELL WEST OF THE AREA INTO THE OPEN GULF OF MEXICO AND
SEAS WILL SUBSIDE TODAY AS WELL. HIGH PRESSURE BUILDING INTO THE
AREA FROM THE ATLANTIC WILL KEEP A MODERATE EASTERLY FLOW IN PLACE
THROUGH FRIDAY WITH SLIGHTLY ELEVATED WINDS AND SEAS...THEN AS THE
RIDGE BUILDS OVER THE AREA ON SATURDAY AND SUNDAY LIGHT WINDS WILL
OCCUR. AFTERNOON SEA BREEZES NEAR THE COAST ARE EXPECTED THE NEXT
FEW DAYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 90 71 89 71 / 40 20 15 10
FMY 89 69 90 68 / 30 10 15 10
GIF 90 67 89 65 / 10 10 10 10
SRQ 89 70 86 67 / 40 20 15 10
BKV 90 65 90 63 / 35 15 10 10
SPG 86 75 86 73 / 40 20 15 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1026 PM CDT THU MAY 3 2012
.MESOSCALE DISCUSSION...
815 PM CDT
MAIN CONCERN FOR THE REST OF THE NIGHT IS FLASH FLOOD POTENTIAL.
TRAINING STORMS OVER NORTHEAST DUPAGE AND NORTHERN COOK COUNTY
CONTINUE TO REGENERATE. SOME ALSO PRODUCING SEVERE HAIL. OTHER
SLOW MOVING HEAVY RAIN PRODUCERS OVER BUREAU-LASALLE
COUNTIES...AND YET ANOTHER CLUSTER OF STORMS MOVING IN FROM
EASTERN IA.
SPC ANALYSIS INDICATES RIBBON OF PRECIPITABLE WATER IN EXCESS OF
1.5 FROM WEST CENTRAL TO NORTHEAST ILLINOIS. THIS IS ALSO AN AREA
OF HIGH 850 MOISTURE TRANSPORT. HRRR INDICATING HEAVIEST RAIN IN
THIS CORRIDOR AS WELL. WILL BE ISSUING A FLASH FLOOD WATCH FOR
OVERNIGHT FOR ALL BUT THE NORTH TIER OF COUNTIES.
ALLSOPP
&&
.DISCUSSION...
315 PM CDT
TONIGHT...
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE ONGOING
OVERNIGHT AND IT IS DIFFICULT TO ADD ANY SPECIFICS THIS AFTERNOON
AS TO WHEN THE HEAVIEST OF ACTIVITY WILL POP AND MOVE ACROSS...AS
GUIDANCE HAS BEEN STRUGGLING TO LATCH ONTO A SOLID SOLUTION. THE
HRRR AND RAP HAVE BEEN PRETTY CONSISTENT FROM RUN TO RUN IN
DEVELOPING CONVECTION ACROSS THE NORTHERN BORDER THIS AFTERNOON
AND EVENING...BUT AS THE MODELS HAVE BEEN UNDER PERFORMING THE LAST
FEW DAYS...NOT GOING TO COMPLETELY BITE OFF ON ANY ONE SOLUTION
HAPPENING THIS EVENING...LEADING TO A LOW CONFIDENCE OVERNIGHT
FORECAST. DO BELIEVE THAT THE ONGOING ACTIVITY FROM MKE TO ROUGHLY
MSN WILL TRY TO WORK SOUTH WHILE MOVING EAST...BUT WILL DEFER TO
SPECIFICS THAT FALL WITHIN THE MESO AFD ABOVE. FRONT WILL SLOWLY
BE SAGGING SOUTH ACROSS SOUTHERN WISCONSIN AND WORK INTO ILLINOIS
THROUGH THE OVERNIGHT HOURS. ACTIVITY WILL THEN BE ON THE WANE
AS WE GET CLOSER TO THE MORNING.
THE STRONG WARM AIR ADVECTION THAT SHOT TEMPERATURES INTO THE 80S
TODAY WILL SHIFT SOUTH. WITH THE FRONT DROPPING THROUGH AND ACROSS
CHICAGO...WINDS WILL FLIP AROUND TO THE NORTHEAST AND PULL A
COOLER MARINE AIRMASS ACROSS MUCH OF THE COASTLINE. MODELS CONTINUE
TO SLOW THIS TREND SLIGHTLY OVER PREVIOUS RUNS...BUT DOES CONTINUE TO
KEEP IT DRAPED ACROSS THE AREA. FORECAST SOUNDINGS AND RAW
NUMERICAL GUIDANCE HIGHLIGHTS GOOD INSTABILITY TO PERSIST SOUTH AND
WEST OF THIS FEATURE...THOUGH THE BEST INSTABILITY WILL BE WEST
ACROSS IOWA...AND OVERALL EFFECTIVE SHEAR WILL IS SUGGESTED TO BE AT
OR BELOW 30 KT INTO THE PEAK OF THE AFTERNOON. SPC HAS MOST OF THE
CWA IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW...BUT IT DOES FOLLOW
THE OVERALL LOCATION OF THE FRONT...FAVORING AREAS WITH THE BEST
INSTABILITY. WITH NO REAL FORCING WIGGLING THROUGH THE FLOW
TOMORROW...THE OVERALL THREAT DOES NOT APPEAR TO BE HIGH...BUT
CANNOT RULE OUT THE POSSIBILITY OF SOME UNORGANIZED CELLS DEVELOPING
WITH MARGINAL SEVERE HAIL AND WIND GUSTS.
DID MAKE BIGGER CHANGES TO THE DAYTIME HIGHS ACROSS LAKE AND COOK
COUNTIES. WITH THE FRONT SAGGING SOUTH OF MOST THE METRO INTO THE
EARLY AFTERNOON...SHOULD SEE TEMPS HIT THEIR PEAK IN THE EARLY
AFTERNOON AND THEN FALL. STILL SOME CONSIDERABLE DIFFERENCES BETWEEN
THE MAV AND THE MET THIS AFTERNOON...WITH A 10+ DEGREE DIFFERENCE
BETWEEN THE TWO. THE THOUGHT IS THAT WITH THE FRONT TO THE
SOUTH...MOST COASTAL AREAS /INCLUDING THE CHICAGO METRO/ WILL SEE
HIGHS PEAKING IN THE UPPER 60S TO AROUND 70 BEFORE FALLING INTO THE
AFTERNOON...THOUGH IF MORE RAIN FALLS OVERNIGHT AND KEEPS CLOUDS
IN...MID 60S COULD BE PUSHING IT.
BY THE WEEKEND...UPPER LEVEL RIDGING ACROSS THE FOUR CORNERS REGION
WILL BEGIN TO SHIFT EAST AND OVERHEAD...BUT CONTINUED DISPARITY
BETWEEN LONG RANGE GUIDANCE IS LEADING TO FURTHER LOW END CONFIDENCE
ON PRECIP CHANCES INTO THE NEXT WEEK. TRENDS ARE INDICATING A
WEAK SHORTWAVE ROLLING ACROSS THE RIDGE LATE SUNDAY AND INTO
MONDAY WILL BRING THE NEXT BEST CHANCE FOR SHOWERS. AS THE RIDGE
SLIDES EAST AND A TROUGH MOVES THROUGH...WILL GENERALLY FALL BACK
INTO A COOLER NORTHWESTERLY FLOW REGIME KEEPING DAYTIME HIGHS
CLOSE TO SEASONAL WITH OFF AND ON CHANCES THROUGH THE WEEK.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* ADDITIONAL ROUNDS OF CONVECTION OVERNIGHT WITH TRAINING CELLS
EXPECTED.
* POTENTIAL FOR SEVERAL HOURS OF THUNDER AT MDW AND POSSIBLY AT
ORD AS WELL.
* NORTHEASTERLY WINDS AND LOW MVFR OR IFR CIGS DEVELOPING EARLY
FRIDAY MORNING.
KJB
//DISCUSSION...UPDATED 03 UTC...
A COMPLEX OF THUNDERSTORMS IS UNDERWAY ACROSS EAST CENTRAL IOWA
INTO WESTERN SECTIONS OF ILLINOIS ALONG INTERSTATE 80. THIS
ACTIVITY SHOULD PROGRESS EASTWARD ACROSS PORTIONS OF NORTHEASTERN
ILLINOIS AND NORTHWESTERN INDIANA AFTER 05 UTC. IT APPEARS THE
HIGHEST THREAT AREA WILL BE KMDW AND KGYY. HOWEVER...KORD AND KDPA
COULD ALSO BE AFFECTED BY THESE STORMS...BUT CONFIDENCE IS LOWER
AT THESE TERMINALS. DUE TO THE TRAINING NATURE OF THE STORMS
THERE IS A GOOD POTENTIAL TO EXPERIENCE SEVERAL HOURS OF THUNDER
WITH HEAVY RAINFALL OVERNIGHT.
//DISCUSSION...UPDATED 00Z...
THE MAIN CONCERNS DURING THE PERIOD WILL THE POTENTIAL FOR SEVERAL
ROUNDS OF CONVECTION THROUGH THIS EVENING/OVERNIGHT AND A GOOD
POTENTIAL TO SEE SOME LOW MVFR AND IFR CIGS ON FRIDAY.
A BROKEN LINE OF CONVECTION HAS DEVELOPED ACROSS NORTHERN ILLINOIS
WITH SOME TRAINING OF CELLS NOTED. A STRONG STORM JUST MOVED ACROSS
KORD...WITH ADDITIONAL CELLS DEVELOPING TO THE WEST ACROSS DUPAGE
COUNTY. THESE STORMS LOOK TO MOVE ACROSS KORD THOUGH THE NEXT HOUR
OR TWO. ADDITIONAL STORMS ARE EXPECTED LATER THIS EVENING INTO THE
OVERNIGHT HOURS AS ADDITIONAL CONVECTION CURRENTLY FIRING UP
ACROSS NORTHERN MO AND FAR SOUTHERN IOWA IS EXPECTED TO MOVE
EASTWARD ACROSS ILLINOIS. THE ENVIRONMENT LOOKS TO SUPPORT
TRAINING CELLS TONIGHT...WHICH COULD LEAD TO SEVERAL HOURS OF THUNDER IN
SOME AREAS. THE BIG QUESTION MARK IS WHERE THESE TRAINING CELLS
WILL SET UP. THERE ARE SOME INDICATIONS THAT THE MAIN AREA OF
CONVECTION COULD SHIFT JUST TO THE SOUTH OF THE TERMINALS THIS
EVENING ALONG AN AREA OF GOOD MOISTURE CONVERGENCE AHEAD OF AN
APPROACHING MID LEVEL SHORT WAVE DISTURBANCE. IF THIS DOES OCCUR
THE TERMINALS WILL MISS OUT ON MOST OF THE ACTIVITY.
THE WINDS WILL TURN NORTHEASTERLY OFF OF LAKE MICHIGAN EARLY ON
FRIDAY MORNING. IT APPEARS THAT LOW CLOUDS WILL ALSO MOVE ACROSS THE
AREA...WITH IFR CIGS POSSIBLE FOR MUCH OF DAY.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN THUNDERSTORMS AFFECTING MDW AGAIN AFTER 05
UTC.
* LOW TO MEDIUM CONFIDENCE IN ADDITIONAL THUNDER AT ORD AFTER 05 UTC.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN LOW MVFR/IFR CIGS ON FRIDAY.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE
FRIDAY INTO THE WEEKEND.
WEDNESDAY...CHANCE SHRA. OTRW...VFR.
KJB
&&
.MARINE...
223 PM CDT
BROAD LOW PRESSURE WILL EVOLVE EAST ACROSS THE CENTRAL PORTION OF
LAKE MICHIGAN TONIGHT. IN ASSOCIATION WITH THIS FEATURE...CLUSTERS
OF THUNDERSTORMS WILL TRAVERSE ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE...SOME OF THESE POTENTIALLY PRODUCING GUSTY WINDS IN EXCESS OF
35 KTS. GUSTY SOUTHWEST WINDS WILL CONTINUE INTO EARLY THIS EVENING
FROM CHICAGO EASTWARD ACROSS NEARSHORE AREAS...POTENTIALLY
CONTINUING INTO SMALL CRAFT ADVISORY CRITERIA THROUGH 8 OR 9 PM.
THE LOW WILL STEER A COLD FRONT SLOWLY SOUTHWARD ACROSS THE LAKE
TONIGHT INTO FRIDAY MORNING. THIS WILL REACH THE SOUTHERN PORTION OF
THE LAKE BY MIDDAY FRIDAY. NORTHEAST WINDS WILL TURN EAST THIS
WEEKEND AS LOW PRESSURE EVOLVES EASTWARD FROM THE CENTRAL
PLAINS...REACHING THE SOUTHERN GREAT LAKES TO MIDDLE OHIO VALLEY BY
SOMETIME EARLY NEXT WEEK.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FLASH FLOOD WATCH...ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032 UNTIL 7 AM FRIDAY.
IN...FLASH FLOOD WATCH...INZ001-INZ002 UNTIL 7 AM FRIDAY.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
824 PM CDT THU MAY 3 2012
.MESOSCALE DISCUSSION...
815 PM CDT
MAIN CONCERN FOR THE REST OF THE NIGHT IS FLASH FLOOD POTENTIAL.
TRAINING STORMS OVER NORTHEAST DUPAGE AND NORTHERN COOK COUNTY
CONTINUE TO REGENERATE. SOME ALSO PRODUCING SEVERE HAIL. OTHER
SLOW MOVING HEAVY RAIN PRODUCERS OVER BUREAU-LASALLE
COUNTIES...AND YET ANOTHER CLUSTER OF STORMS MOVING IN FROM
EASTERN IA.
SPC ANALYSIS INDICATES RIBBON OF PRECIPITABLE WATER IN EXCESS OF
1.5 FROM WEST CENTRAL TO NORTHEAST ILLINOIS. THIS IS ALSO AN AREA
OF HIGH 850 MOISTURE TRANSPORT. HRRR INDICATING HEAVIEST RAIN IN
THIS CORRIDOR AS WELL. WILL BE ISSUING A FLASH FLOOD WATCH FOR
OVERNIGHT FOR ALL BUT THE NORTH TIER OF COUNTIES.
ALLSOPP
&&
.DISCUSSION...
315 PM CDT
TONIGHT...
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE ONGOING
OVERNIGHT AND IT IS DIFFICULT TO ADD ANY SPECIFICS THIS AFTERNOON
AS TO WHEN THE HEAVIEST OF ACTIVITY WILL POP AND MOVE ACROSS...AS
GUIDANCE HAS BEEN STRUGGLING TO LATCH ONTO A SOLID SOLUTION. THE
HRRR AND RAP HAVE BEEN PRETTY CONSISTENT FROM RUN TO RUN IN
DEVELOPING CONVECTION ACROSS THE NORTHERN BORDER THIS AFTERNOON
AND EVENING...BUT AS THE MODELS HAVE BEEN UNDER PERFORMING THE LAST
FEW DAYS...NOT GOING TO COMPLETELY BITE OFF ON ANY ONE SOLUTION
HAPPENING THIS EVENING...LEADING TO A LOW CONFIDENCE OVERNIGHT
FORECAST. DO BELIEVE THAT THE ONGOING ACTIVITY FROM MKE TO ROUGHLY
MSN WILL TRY TO WORK SOUTH WHILE MOVING EAST...BUT WILL DEFER TO
SPECIFICS THAT FALL WITHIN THE MESO AFD ABOVE. FRONT WILL SLOWLY
BE SAGGING SOUTH ACROSS SOUTHERN WISCONSIN AND WORK INTO ILLINOIS
THROUGH THE OVERNIGHT HOURS. ACTIVITY WILL THEN BE ON THE WANE
AS WE GET CLOSER TO THE MORNING.
THE STRONG WARM AIR ADVECTION THAT SHOT TEMPERATURES INTO THE 80S
TODAY WILL SHIFT SOUTH. WITH THE FRONT DROPPING THROUGH AND ACROSS
CHICAGO...WINDS WILL FLIP AROUND TO THE NORTHEAST AND PULL A
COOLER MARINE AIRMASS ACROSS MUCH OF THE COASTLINE. MODELS CONTINUE
TO SLOW THIS TREND SLIGHTLY OVER PREVIOUS RUNS...BUT DOES CONTINUE TO
KEEP IT DRAPED ACROSS THE AREA. FORECAST SOUNDINGS AND RAW
NUMERICAL GUIDANCE HIGHLIGHTS GOOD INSTABILITY TO PERSIST SOUTH AND
WEST OF THIS FEATURE...THOUGH THE BEST INSTABILITY WILL BE WEST
ACROSS IOWA...AND OVERALL EFFECTIVE SHEAR WILL IS SUGGESTED TO BE AT
OR BELOW 30 KT INTO THE PEAK OF THE AFTERNOON. SPC HAS MOST OF THE
CWA IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW...BUT IT DOES FOLLOW
THE OVERALL LOCATION OF THE FRONT...FAVORING AREAS WITH THE BEST
INSTABILITY. WITH NO REAL FORCING WIGGLING THROUGH THE FLOW
TOMORROW...THE OVERALL THREAT DOES NOT APPEAR TO BE HIGH...BUT
CANNOT RULE OUT THE POSSIBILITY OF SOME UNORGANIZED CELLS DEVELOPING
WITH MARGINAL SEVERE HAIL AND WIND GUSTS.
DID MAKE BIGGER CHANGES TO THE DAYTIME HIGHS ACROSS LAKE AND COOK
COUNTIES. WITH THE FRONT SAGGING SOUTH OF MOST THE METRO INTO THE
EARLY AFTERNOON...SHOULD SEE TEMPS HIT THEIR PEAK IN THE EARLY
AFTERNOON AND THEN FALL. STILL SOME CONSIDERABLE DIFFERENCES BETWEEN
THE MAV AND THE MET THIS AFTERNOON...WITH A 10+ DEGREE DIFFERENCE
BETWEEN THE TWO. THE THOUGHT IS THAT WITH THE FRONT TO THE
SOUTH...MOST COASTAL AREAS /INCLUDING THE CHICAGO METRO/ WILL SEE
HIGHS PEAKING IN THE UPPER 60S TO AROUND 70 BEFORE FALLING INTO THE
AFTERNOON...THOUGH IF MORE RAIN FALLS OVERNIGHT AND KEEPS CLOUDS
IN...MID 60S COULD BE PUSHING IT.
BY THE WEEKEND...UPPER LEVEL RIDGING ACROSS THE FOUR CORNERS REGION
WILL BEGIN TO SHIFT EAST AND OVERHEAD...BUT CONTINUED DISPARITY
BETWEEN LONG RANGE GUIDANCE IS LEADING TO FURTHER LOW END CONFIDENCE
ON PRECIP CHANCES INTO THE NEXT WEEK. TRENDS ARE INDICATING A
WEAK SHORTWAVE ROLLING ACROSS THE RIDGE LATE SUNDAY AND INTO
MONDAY WILL BRING THE NEXT BEST CHANCE FOR SHOWERS. AS THE RIDGE
SLIDES EAST AND A TROUGH MOVES THROUGH...WILL GENERALLY FALL BACK
INTO A COOLER NORTHWESTERLY FLOW REGIME KEEPING DAYTIME HIGHS
CLOSE TO SEASONAL WITH OFF AND ON CHANCES THROUGH THE WEEK.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* POTENTIAL FOR ADDITIONAL ROUNDS OF CONVECTION THIS
EVENING/OVERNIGHT.
* NORTHEASTERLY WINDS AND LOW MVFR OR IFR CIGS DEVELOPING EARLY
FRIDAY MORNING.
KJB
//DISCUSSION...UPDATED 00Z...
THE MAIN CONCERNS DURING THE PERIOD WILL THE POTENTIAL FOR SEVERAL
ROUNDS OF CONVECTION THROUGH THIS EVENING/OVERNIGHT AND A GOOD
POTENTIAL TO SEE SOME LOW MVFR AND IFR CIGS ON FRIDAY.
A BROKEN LINE OF CONVECTION HAS DEVELOPED ACROSS NORTHERN ILLINOIS
WITH SOME TRAINING OF CELLS NOTED. A STRONG STORM JUST MOVED ACROSS
KORD...WITH ADDITIONAL CELLS DEVELOPING TO THE WEST ACROSS DUPAGE
COUNTY. THESE STORMS LOOK TO MOVE ACROSS KORD THOUGH THE NEXT HOUR
OR TWO. ADDITIONAL STORMS ARE EXPECTED LATER THIS EVENING INTO THE
OVERNIGHT HOURS AS ADDITIONAL CONVECTION CURRENTLY FIRING UP
ACROSS NORTHERN MO AND FAR SOUTHERN IOWA IS EXPECTED TO MOVE
EASTWARD ACROSS ILLINOIS. THE ENVIRONMENT LOOKS TO SUPPORT
TRAINING CELLS TONIGHT...WHICH COULD LEAD TO SEVERAL HOURS OF THUNDER IN
SOME AREAS. THE BIG QUESTION MARK IS WHERE THESE TRAINING CELLS
WILL SET UP. THERE ARE SOME INDICATIONS THAT THE MAIN AREA OF
CONVECTION COULD SHIFT JUST TO THE SOUTH OF THE TERMINALS THIS
EVENING ALONG AN AREA OF GOOD MOISTURE CONVERGENCE AHEAD OF AN
APPROACHING MID LEVEL SHORT WAVE DISTURBANCE. IF THIS DOES OCCUR
THE TERMINALS WILL MISS OUT ON MOST OF THE ACTIVITY.
THE WINDS WILL TURN NORTHEASTERLY OFF OF LAKE MICHIGAN EARLY ON
FRIDAY MORNING. IT APPEARS THAT LOW CLOUDS WILL ALSO MOVE ACROSS THE
AREA...WITH IFR CIGS POSSIBLE FOR MUCH OF DAY.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW CONFIDENCE ON THUNDERSTORMS TRENDS LATER THIS EVENING/OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN LOW MVFR/IFR CIGS ON FRIDAY.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE
FRIDAY INTO THE WEEKEND.
WEDNESDAY...CHANCE SHRA. OTRW...VFR.
KJB
&&
.MARINE...
223 PM CDT
BROAD LOW PRESSURE WILL EVOLVE EAST ACROSS THE CENTRAL PORTION OF
LAKE MICHIGAN TONIGHT. IN ASSOCIATION WITH THIS FEATURE...CLUSTERS
OF THUNDERSTORMS WILL TRAVERSE ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE...SOME OF THESE POTENTIALLY PRODUCING GUSTY WINDS IN EXCESS OF
35 KTS. GUSTY SOUTHWEST WINDS WILL CONTINUE INTO EARLY THIS EVENING
FROM CHICAGO EASTWARD ACROSS NEARSHORE AREAS...POTENTIALLY
CONTINUING INTO SMALL CRAFT ADVISORY CRITERIA THROUGH 8 OR 9 PM.
THE LOW WILL STEER A COLD FRONT SLOWLY SOUTHWARD ACROSS THE LAKE
TONIGHT INTO FRIDAY MORNING. THIS WILL REACH THE SOUTHERN PORTION OF
THE LAKE BY MIDDAY FRIDAY. NORTHEAST WINDS WILL TURN EAST THIS
WEEKEND AS LOW PRESSURE EVOLVES EASTWARD FROM THE CENTRAL
PLAINS...REACHING THE SOUTHERN GREAT LAKES TO MIDDLE OHIO VALLEY BY
SOMETIME EARLY NEXT WEEK.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
715 PM CDT THU MAY 3 2012
.MESOSCALE DISCUSSION...
550 PM CDT
ISOLATED CONVECTIVE CELLS HAVE DEVELOPED FROM NEAR PEORIA
NORTHEAST TO LA SALLE COUNTY...ALONG WITH SOME ECHOES OVER
CHICAGO. THIS DEVELOPMENT ALIGNS WELL WITH LOW-LEVEL SPEED AND
MOISTURE CONVERGENCE. ALONG THIS RIBBON...A LOCALIZED POOL OF 67
TO 70 TDS EXIST...AND AN ASSOCIATED UNCAPPED MLCAPE AXIS OF 3000
TO 4000 J/KG PER MODIFIED RUC SOUNDINGS IN THE SOUTHWEST AND
CENTRAL FORECAST AREA. AMDAR SOUNDINGS TOWARD CHICAGO DO STILL
SHOW A MINOR CAP IN PLACE WHEN LIFTING FROM THE SURFACE...ALTHOUGH
PLENTY OF CAPE ABOVE IT. A MAXIMA OF PRESSURE FALLS OF 3 TO 6 MB
PER 3 HOURS WAS ANALYZED ACROSS THE ILLINOIS RIVER VALLEY AREA OF
CENTRAL IL...POSSIBLY ASSOCIATED WITH A WEAK RIPPLE TRACKING
NORTHEAST ALONG THE SURFACE BOUNDARY.
IF THE ANALYSIS OF CAPE/CIN IS CORRECT...THE CONVECTION SHOULD
FURTHER ENHANCE TO THE NORTHEAST WITH THE CONVERGENCE IN SUCH A
RICH POOL OF UNCAPPED INSTABILITY. FURTHER NORTH AND NORTHEAST
TOWARD CHICAGO...CUMULUS CONGESTUS IS TRYING TO DEVELOP AS
WELL...AND COULD SEE THINGS FILL IN BETWEEN THE ONGOING ECHOES.
THE HRRR AND RAP HAVE BEEN FORECASTING THIS ALL AFTERNOON...THOUGH
THEY HAVE ALREADY BEEN TOO ROBUST. DEEP LAYER SHEAR OF 30 TO 40 KT
WILL BE ENOUGH TO SUPPORT ORGANIZED UPDRAFTS AND OVERALL MORE
PERSISTENT STORMS THAN WHAT WE HAVE SEEN LOCALLY SO FAR. IF STORMS
DO GET DEVELOPING...THEY SHOULD BE ABLE TO FESTER AND CONTINUE NEW
GROWTH OFF OF OUTFLOWS DUE TO SUCH HIGH INSTABILITY. GIVEN THE
INSTABILITY WITH THE SHEAR...THERE CERTAINLY WILL BE PLENTY FOR
HAIL AND WIND POTENTIAL IF ANY STORMS PERSIST AWHILE. THE LOW-
LEVEL WIND FIELD HAS VEERED QUITE A BIT FROM AN HOUR OR TWO AGO IN
THE SOUTHWEST FORECAST AREA. LOW LCLS...SUFFICIENT LOW-LEVEL
CAPE...AND THE PRESENCE OF MULTIPLE BOUNDARIES PER SATELLITE
ANALYSIS MAY OFFSET THIS THOUGH AND CONTINUE TO PROVIDE SOME
TORNADO POTENTIAL. THIS IS ESPECIALLY TRUE IN AND AROUND THE
TORNADO WATCH AREA...WHERE 15 TO 20 KT 0-1KM SHEAR IS PRESENT.
MTF
&&
.DISCUSSION...
315 PM CDT
TONIGHT...
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE ONGOING
OVERNIGHT AND IT IS DIFFICULT TO ADD ANY SPECIFICS THIS AFTERNOON
AS TO WHEN THE HEAVIEST OF ACTIVITY WILL POP AND MOVE ACROSS...AS
GUIDANCE HAS BEEN STRUGGLING TO LATCH ONTO A SOLID SOLUTION. THE
HRRR AND RAP HAVE BEEN PRETTY CONSISTENT FROM RUN TO RUN IN
DEVELOPING CONVECTION ACROSS THE NORTHERN BORDER THIS AFTERNOON
AND EVENING...BUT AS THE MODELS HAVE BEEN UNDER PERFORMING THE LAST
FEW DAYS...NOT GOING TO COMPLETELY BITE OFF ON ANY ONE SOLUTION
HAPPENING THIS EVENING...LEADING TO A LOW CONFIDENCE OVERNIGHT
FORECAST. DO BELIEVE THAT THE ONGOING ACTIVITY FROM MKE TO ROUGHLY
MSN WILL TRY TO WORK SOUTH WHILE MOVING EAST...BUT WILL DEFER TO
SPECIFICS THAT FALL WITHIN THE MESO AFD ABOVE. FRONT WILL SLOWLY
BE SAGGING SOUTH ACROSS SOUTHERN WISCONSIN AND WORK INTO ILLINOIS
THROUGH THE OVERNIGHT HOURS. ACTIVITY WILL THEN BE ON THE WANE
AS WE GET CLOSER TO THE MORNING.
THE STRONG WARM AIR ADVECTION THAT SHOT TEMPERATURES INTO THE 80S
TODAY WILL SHIFT SOUTH. WITH THE FRONT DROPPING THROUGH AND ACROSS
CHICAGO...WINDS WILL FLIP AROUND TO THE NORTHEAST AND PULL A
COOLER MARINE AIRMASS ACROSS MUCH OF THE COASTLINE. MODELS CONTINUE
TO SLOW THIS TREND SLIGHTLY OVER PREVIOUS RUNS...BUT DOES CONTINUE TO
KEEP IT DRAPED ACROSS THE AREA. FORECAST SOUNDINGS AND RAW
NUMERICAL GUIDANCE HIGHLIGHTS GOOD INSTABILITY TO PERSIST SOUTH AND
WEST OF THIS FEATURE...THOUGH THE BEST INSTABILITY WILL BE WEST
ACROSS IOWA...AND OVERALL EFFECTIVE SHEAR WILL IS SUGGESTED TO BE AT
OR BELOW 30 KT INTO THE PEAK OF THE AFTERNOON. SPC HAS MOST OF THE
CWA IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW...BUT IT DOES FOLLOW
THE OVERALL LOCATION OF THE FRONT...FAVORING AREAS WITH THE BEST
INSTABILITY. WITH NO REAL FORCING WIGGLING THROUGH THE FLOW
TOMORROW...THE OVERALL THREAT DOES NOT APPEAR TO BE HIGH...BUT
CANNOT RULE OUT THE POSSIBILITY OF SOME UNORGANIZED CELLS DEVELOPING
WITH MARGINAL SEVERE HAIL AND WIND GUSTS.
DID MAKE BIGGER CHANGES TO THE DAYTIME HIGHS ACROSS LAKE AND COOK
COUNTIES. WITH THE FRONT SAGGING SOUTH OF MOST THE METRO INTO THE
EARLY AFTERNOON...SHOULD SEE TEMPS HIT THEIR PEAK IN THE EARLY
AFTERNOON AND THEN FALL. STILL SOME CONSIDERABLE DIFFERENCES BETWEEN
THE MAV AND THE MET THIS AFTERNOON...WITH A 10+ DEGREE DIFFERENCE
BETWEEN THE TWO. THE THOUGHT IS THAT WITH THE FRONT TO THE
SOUTH...MOST COASTAL AREAS /INCLUDING THE CHICAGO METRO/ WILL SEE
HIGHS PEAKING IN THE UPPER 60S TO AROUND 70 BEFORE FALLING INTO THE
AFTERNOON...THOUGH IF MORE RAIN FALLS OVERNIGHT AND KEEPS CLOUDS
IN...MID 60S COULD BE PUSHING IT.
BY THE WEEKEND...UPPER LEVEL RIDGING ACROSS THE FOUR CORNERS REGION
WILL BEGIN TO SHIFT EAST AND OVERHEAD...BUT CONTINUED DISPARITY
BETWEEN LONG RANGE GUIDANCE IS LEADING TO FURTHER LOW END CONFIDENCE
ON PRECIP CHANCES INTO THE NEXT WEEK. TRENDS ARE INDICATING A
WEAK SHORTWAVE ROLLING ACROSS THE RIDGE LATE SUNDAY AND INTO
MONDAY WILL BRING THE NEXT BEST CHANCE FOR SHOWERS. AS THE RIDGE
SLIDES EAST AND A TROUGH MOVES THROUGH...WILL GENERALLY FALL BACK
INTO A COOLER NORTHWESTERLY FLOW REGIME KEEPING DAYTIME HIGHS
CLOSE TO SEASONAL WITH OFF AND ON CHANCES THROUGH THE WEEK.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* POTENTIAL FOR ADDITIONAL ROUNDS OF CONVECTION THIS
EVENING/OVERNIGHT.
* NORTHEASTERLY WINDS AND LOW MVFR OR IFR CIGS DEVELOPING EARLY
FRIDAY MORNING.
KJB
//DISCUSSION...UPDATED 00Z...
THE MAIN CONCERNS DURING THE PERIOD WILL THE POTENTIAL FOR SEVERAL
ROUNDS OF CONVECTION THROUGH THIS EVENING/OVERNIGHT AND A GOOD
POTENTIAL TO SEE SOME LOW MVFR AND IFR CIGS ON FRIDAY.
A BROKEN LINE OF CONVECTION HAS DEVELOPED ACROSS NORTHERN ILLINOIS
WITH SOME TRAINING OF CELLS NOTED. A STRONG STORM JUST MOVED ACROSS
KORD...WITH ADDITIONAL CELLS DEVELOPING TO THE WEST ACROSS DUPAGE
COUNTY. THESE STORMS LOOK TO MOVE ACROSS KORD THOUGH THE NEXT HOUR
OR TWO. ADDITIONAL STORMS ARE EXPECTED LATER THIS EVENING INTO THE
OVERNIGHT HOURS AS ADDITIONAL CONVECTION CURRENTLY FIRING UP
ACROSS NORTHERN MO AND FAR SOUTHERN IOWA IS EXPECTED TO MOVE
EASTWARD ACROSS ILLINOIS. THE ENVIRONMENT LOOKS TO SUPPORT
TRAINING CELLS TONIGHT...WHICH COULD LEAD TO SEVERAL HOURS OF THUNDER IN
SOME AREAS. THE BIG QUESTION MARK IS WHERE THESE TRAINING CELLS
WILL SET UP. THERE ARE SOME INDICATIONS THAT THE MAIN AREA OF
CONVECTION COULD SHIFT JUST TO THE SOUTH OF THE TERMINALS THIS
EVENING ALONG AN AREA OF GOOD MOISTURE CONVERGENCE AHEAD OF AN
APPROACHING MID LEVEL SHORT WAVE DISTURBANCE. IF THIS DOES OCCUR
THE TERMINALS WILL MISS OUT ON MOST OF THE ACTIVITY.
THE WINDS WILL TURN NORTHEASTERLY OFF OF LAKE MICHIGAN EARLY ON
FRIDAY MORNING. IT APPEARS THAT LOW CLOUDS WILL ALSO MOVE ACROSS THE
AREA...WITH IFR CIGS POSSIBLE FOR MUCH OF DAY.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW CONFIDENCE ON THUNDERSTORMS TRENDS LATER THIS EVENING/OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN LOW MVFR/IFR CIGS ON FRIDAY.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE
FRIDAY INTO THE WEEKEND.
WEDNESDAY...CHANCE SHRA. OTRW...VFR.
KJB
&&
.MARINE...
223 PM CDT
BROAD LOW PRESSURE WILL EVOLVE EAST ACROSS THE CENTRAL PORTION OF
LAKE MICHIGAN TONIGHT. IN ASSOCIATION WITH THIS FEATURE...CLUSTERS
OF THUNDERSTORMS WILL TRAVERSE ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE...SOME OF THESE POTENTIALLY PRODUCING GUSTY WINDS IN EXCESS OF
35 KTS. GUSTY SOUTHWEST WINDS WILL CONTINUE INTO EARLY THIS EVENING
FROM CHICAGO EASTWARD ACROSS NEARSHORE AREAS...POTENTIALLY
CONTINUING INTO SMALL CRAFT ADVISORY CRITERIA THROUGH 8 OR 9 PM.
THE LOW WILL STEER A COLD FRONT SLOWLY SOUTHWARD ACROSS THE LAKE
TONIGHT INTO FRIDAY MORNING. THIS WILL REACH THE SOUTHERN PORTION OF
THE LAKE BY MIDDAY FRIDAY. NORTHEAST WINDS WILL TURN EAST THIS
WEEKEND AS LOW PRESSURE EVOLVES EASTWARD FROM THE CENTRAL
PLAINS...REACHING THE SOUTHERN GREAT LAKES TO MIDDLE OHIO VALLEY BY
SOMETIME EARLY NEXT WEEK.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
323 AM CDT WED MAY 2 2012
.DISCUSSION...
935 PM CDT
SURFACE QUASI-WARM FRONT WAS ANALYZED ALONG THE SOUTHERN PERIPHERY
OF THE WFO LOT CWA THIS EVENING...HAVING BEEN SUPPRESSED BY
WELL-DEFINED MID-LEVEL VORT AND ASSOCIATED SURFACE WAVE THIS
AFTERNOON. EVENING WATER VAPOR IMAGERY INDICATES THIS MID-LEVEL
CIRCULATION IS NOW OVER INDIANA AND SOUTHERN LOWER MICHIGAN AND
MOVING AWAY FROM THE CWA...WITH THE AREA OF RAIN ASSOCIATED WITH
THIS FEATURE ALSO WEAKENING AND MOVING OUT OF THE AREA AT THIS TIME
WITH ONLY A FEW WEAK RADAR RETURNS LINGERING OVER FAR SOUTHERN LAKE
MICHIGAN AND PARTS OF THE EAST/SOUTHEAST CHICAGO METRO COUNTIES.
HAVE ADJUSTED POPS/WX GRIDS ACCORDINGLY...WITH LITTLE POTENTIAL FOR
ORGANIZED PRECIP ANTICIPATED THROUGH AT LEAST MIDNIGHT IN SUBSIDENT
WAKE OF DEPARTING MID-LEVEL VORT.
THE WARM FRONT IS STILL PROGGED TO LIFT NORTH OVERNIGHT...AND THEN
NORTH OF THE FORECAST AREA WEDNESDAY MORNING. SEVERAL FORECAST
CHALLENGES REMAIN FOR THE OVERNIGHT PERIOD HOWEVER...INCLUDING
STEADY/RISING TEMPERATURES WITH WARM FRONT...DEVELOPMENT OF PATCHY
DENSE FOG...AND THE POTENTIAL FOR RENEWED SHOWER AND THUNDERSTORM
DEVELOPMENT DURING THE LATE NIGHT HOURS.
GOES 11-3.9 MICRON IR IMAGERY INDICATES LOW STRATUS IN EASTERLY
LOW-LEVEL FLOW NORTH OF THE SURFACE WARM FRONT AT 02Z...WITH A FEW
NORTHERN IL LOCATIONS SUCH AS VYS DEVELOPING PATCHY DENSE FOG WHERE
SOME BREAKS HAVE FORMED ALONG THE SOUTHERN EDGE OF THE STRATUS DECK.
FARTHER NORTH...A SLOW LOWERING TREND HAS BEEN NOTED IN VISIBILITY
WITH AREAS OF 1-3SM FOG EXPECTED TO PERSIST DURING THE NIGHT WITH
IMPROVEMENT LIKELY FROM THE SOUTH AS WARM SECTOR SPREADS NORTH.
TEMPERATURES HAVE FALLEN INTO THE LOW/MID 50S ALONG THE LAKE
MICHIGAN SHORE...AND WILL LIKELY DIP TO THE UPPER 50S/AROUND 60
ELSEWHERE NORTH OF THE WARM FRONT AND INTO THE LOWER 60S FARTHER
SOUTH. TEMPERATURES WILL THEN LIKELY BECOME STEADY...AND EVEN RISE
LATE TONIGHT HOWEVER AS THE FRONT LIFTS NORTH.
AS FOR PRECIPITATION TRENDS...EXPECT SEVERAL HOURS OF DRY WEATHER AS
MENTIONED ABOVE. EVENING UPPER AIR ANALYSIS DOES INDICATE A 40 KT
MID-LEVEL SPEED MAX UPSTREAM OVER KANSAS THAT IS PROGGED TO
TRANSLATE NORTHEAST OVERNIGHT ALONG WITH A VERY MOIST WARM SECTOR
AIRMASS WITH H9 DEWPOINTS OF 16C NOTED UPSTREAM. SEVERAL RECENT RUNS
OF THE HRRR HAVE DEPICTED ELEVATED CONVECTION DEVELOPING ACROSS
SOUTHEAST IOWA AND MISSOURI THIS EVENING ALONG THE WARM FRONTAL ZONE
AND SPREADING INTO IL BY MIDNIGHT...AND WHILE DEEP MOIST CONVERGENCE
IS ANALYZED ALONG THE FRONT...SATELLITE AND RADAR TRENDS SUGGEST
THIS APPEARS TO BE OVER-FORECAST. A MORE LIKELY SCENARIO IS FOR MCS
OVER FAR SOUTHWESTERN MINNESOTA AND NORTHWEST IOWA TO PROPAGATE
EAST-SOUTHEAST ALONG THE FRONTAL ZONE AND EVENTUALLY WEAKEN AS IT
MOVES INTO THE FORECAST AREA DURING THE PRE-DAWN HOURS OF EARLY
WEDNESDAY.
RATZER
//PREV DISCUSSION...
304 PM CDT
CONCERNS FOR LATEST FORECAST PACKAGE WILL BE DEALING WITH ONGOING
CONVECTIVE CHANCES THROUGH THE WEEK...AS WELL AS IMPACT ON
TEMPERATURES.
TODAY...WELL DEFINED MCV FROM REMNANT MCC MOVING ACROSS CENTRAL
ILLINOIS WITH LINGERING SHOWERS ACROSS NORTHERN ILLINOIS AND
NORTHWEST INDIANA. THIS AFTERNOON...VERY MODEST MUCAPE (LESS THAN
100 J/KG) ACROSS PORTIONS OF NORTHERN ILLINOIS THIS AFTERNOON AND
LIFT ASSOCD WITH MCV PUSHING EAST ACROSS THE REGION WILL SUPPORT
ONGOING SHOWERS...BUT EXPECT THUNDER CHANCES TO BE FAIRLY LOW WITH
LIMITED INSTABILITY. ONCE THIS AREA OF PRECIP MOVES EAST...EXPECT A
DRY PERIOD THIS EVENING WITH SUBSIDENCE IN PLACE.
TONIGHT...SURFACE FRONT WILL LIFT NORTH OF THE REGION THIS EVENING
WITH SURFACE TEMPS/DEWPOINTS RISING INTO THE 60S OVERNIGHT. H5
HEIGHT RISES INITIALLY SHOULD INHIBIT ANY DEEP CONVECTION...HOWEVER
A WEAK IMPULSE MOVING EAST ACROSS IOWA WILL MOVE INTO NORTHERN
ILLINOIS AFTER MIDNIGHT TONIGHT AND 50 KT LOW LEVEL JET DEVELOPS OVER
EASTERN KANSAS/NORTHWEST MISSOURI EXTENDING INTO NORTHWESTERN
ILLINOIS. MAX THETA-E CONVERGENCE SETS UP OVER EASTERN IOWA/NORTHERN
ILLINOIS AS MUCAPE RISES TO NEAR 2000 J/KG. BELIEVE THIS WILL BE
BEST FOCUS FOR CONVECTION TONIGHT AND ADJUSTED POPS
ACCORDINGLY...WITH BEST CHANCES //LIKELY POPS// ACROSS
NORTH/NORTHEASTERN PORTIONS OF THE CWA AND TRAILING OFF SOMEWHAT TO
THE SOUTHWEST. AS FAR AS THE SEVERE THREAT TONIGHT...GIVEN THE
UNFAVORABLE DIURNAL TIMING...EXPECT MAINLY ELEVATED ACTIVITY NORTH
OF THE FRONT WITH A MARGINAL SEVERE THREAT GIVEN 30 KT OF DEEP LAYER
SHEAR AND SKINNY CAPE PROFILES.
WEDNESDAY AND WEDNESDAY NIGHT...MURKY SCENARIO PRESENTS ITSELF
WEDNESDAY AND WILL LIKELY HINGE ON COLD POOL/OUTFLOW DEVELOPMENT
FROM TONIGHTS CONVECTION. SYNOPTICALLY...WE SHOULD BE WELL INTO THE
WARM SECTOR WITH SOME GUIDANCE NOW SUGGESTING TEMPERATURES INTO THE
LOW 90S SOUTH OF I-80. WAS MORE CONSERVATIVE THAN THAT...BUT DID
BUMP UP TEMPERATURES SLIGHTLY FROM GOING FORECAST. VERY WEAK LAPSE
RATES BETWEEN 900-700MB AND MODEST INVERSION WILL HELP KEEP THE
ATMOSPHERE WEAKLY CAPPED...BUT STRONG INSTABILITY IS EXPECTED TO
DEVELOP WITH NAM INDICATING MLCAPE VALUES REACHING 3000 J/KG BY
WEDNESDAY AFTERNOON. MODELS DO NOT INDICATE ANY UPPER LEVEL SUPPORT
FOR LARGE SCALE ASCENT THIS FAR SOUTH AND MAIN UNCERTAINTY HINGES ON
OUTFLOW DEVELOPMENT PUSHING EFFECTIVE WARM FRONT FARTHER SOUTH AND
BECOMING FOCUS FOR DEVELOPMENT AS SUGGESTED BY 12Z LSX WRF AS WELL
AS THE 12Z NAM RUNS. MOST OTHER GUIDANCE SEEMS TO FOCUS ON AREAS
FARTHER NORTH. GIVEN HIGH DEGREE OF UNCERTAINTY...OPTED TO LEAVE
POPS AS THEY WERE...WITH LOW CHANCE POPS ACROSS THE NORTH AND SLIGHT
CHANCE ACROSS THE SOUTH. GIVEN THIS...THERE IS CONDITIONAL THREAT
FOR SEVERE WEATHER SHOULD THUNDERSTORMS DEVELOP. MODEST WESTERLIES
ALOFT WILL LEAD TO MARGINAL SHEAR...PARTICULARLY ACROSS NORTHERN
PORTIONS OF THE CWA....ALONG WITH THE STRONG INSTABILITY TO SUPPORT
ORGANIZED SEVERE WEATHER WITH MAIN THREATS BEING LARGE HAIL AND
DAMAGING WINDS. WEDNESDAY NIGHT...LOW LEVEL JET IS FORECAST TO
DEVELOP INTO EASTERN NEBRASKA INTO IOWA WITH MEAN DEEP LAYER FLOW
STEERING ANY RESULTANT DEVELOPMENT TO THE EAST-NORTHEAST.
AGAIN...CHANCES ARE BETTER NORTH OF THE CWA BUT WILL MAINTAIN SOME
LOW CHANCE POPS INTO THE NORTHERN PORTIONS OF ILLINOIS WEDNESDAY
NIGHT. STILL FIRMLY INTO THE WARM SECTOR WEDNESDAY NIGHT...EXPECT
TEMPERATURES TO REMAIN UNSEASONABLY WARM...STAYING PROPPED UP IN THE
MID 60S.
THURSDAY THROUGH FRIDAY...VERY SIMILAR SETUP THURSDAY AS COMPARED TO
WEDNESDAY WITH ONGOING ISSUES WITH BOUNDARY PLACEMENT. BY THURSDAY
NIGHT HOWEVER...FRONT MAKES A PUSH TO THE SOUTH ACROSS THE AREA WITH
BETTER CHANCES OF PRECIP ACROSS ILLINOIS AND INDIANA. GUIDANCE IN
FAIRLY DECENT TIMING FROPA EARLY FRIDAY. AS THE FRONT SWEEPS ACROSS
THE REGION...EXPECT TEMPERATURES TO QUICKLY FALL FRIDAY
EVENING...PARTICULARLY AREAS CLOSER TO THE LAKE.
EXTENDED FORECAST...SATURDAY THROUGH TUESDAY...FRONTAL BOUNDARY IS
EXPECTED TO STALL TO OUR SOUTH THEN LIFT BACK NORTH ON
SATURDAY...LINGERING ACROSS THE REGION THROUGH THE WEEKEND AND
BRINGING ADDITIONAL CHANCES FOR SHOWERS AND THUNDERSTORMS. THERE IS
A GREAT DEAL OF UNCERTAINTY REGARDING ANY PRECISE TIMING ON PRECIP
AS WELL AS SPECIFICS ON TEMPERATURES AND WHERE THE BAROCLINIC ZONE
SETS UP. SUNDAY FOR EXAMPLE...MODELS INDICATE A NEAR 20 DEGREE
SPREAD ACROSS THE CWA. GIVEN UNCERTAINTY...DID NOT STRAY FROM
BLENDED MODEL SOLUTION FOR THE EXTENDED PORTION OF THE FORECAST. BMD
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PERIODS OF IFR CIGS/VIS THROUGH THE EARLY MORNING HOURS.
* CHANCE FOR SCT SHOWERS/ISOLD THUNDERSTORMS DEVELOPING DURING THE
EARLY MORNING HOURS.
* GUSTY SOUTHWEST WINDS WEDNESDAY AFTERNOON.
KREIN
//DISCUSSION...UPDATED 06Z...
THE VERY SLOPPY WEATHER WILL CONTINUE FOR THE NRN IL/NWRN INDIANA
TERMINALS WITH MULTIPLE CONCERNS. FOR THE NEXT FEW HOURS...THE
FOCUS WILL BE ON CIGS/VIS. THE DENSER LOW STRATUS IS SHOWING SIGNS
OF SCATTERING...BUT AS THIS OCCURS...VISIBILITY SHOULD DROP. IN
GENERAL...LOCATIONS WITH IMPROVING CEILINGS SHOULD SEE VIS DROP TO
IFR/LIFR WHILE LOCATIONS WHERE THE IFR/LIFR CIGS
REMAIN...VISIBILITY SHOULD BE 2-3SM. ANY WAY YOU CUT
IT...CATEGORICALLY...THERE WILL BE WIDESPREAD IFR/LIFR CONDITIONS
ACROSS NRN IL/IN FOR THE NEXT SEVERAL HOURS.
SHRA/TSRA WILL INCREASINGLY BECOME A CONCERN THROUGH THE NIGHT AS
WELL. LATEST RADAR TRENDS SHOW SCT SHRA DEVELOPING NORTH OF THE
WARM FRONT...IN A ZONE OF STRENGTHENING WARM ADVECTION AND
ISENTROPIC LIFT OVER NRN IL. THIS SCT ACTIVITY IS WELL IN ADVANCE
OF THE SOLID LINE OF CONVECTION MOVING EWD THROUGH IOWA AND SRN
MN. WHILE THE TRENDS IN THE SHORT TERM FORECAST MODELS INDICATE
THAT THE SOLID LINE SHOULD BREAK UP AND WEAKEN THROUGH THE
REMAINDER OF THE NIGHT...WITH THE STRONGEST ACTIVE TS REMAINING
NORTH OF THE IL/WI BORDER...NOT REAL CONFIDENT IN THIS IDEA GIVEN
THE LATEST TRENDS OF STRENGTHENING OF THE LINE OVER WRN
IOWA...INVOF A DEVELOPING SFC WAVE. SO...WHILE HAVE MAINTAINED THE
IDEA OF SCT TS IN THE TAFS FOR THE EARLY MORNING HOURS...WILL
MONITOR CLOSELY TO SEE IF THE TS COVERAGE WILL NEED TO BE BOLSTERED.
FOR THE REMAINDER OF THE DAY...WINDS WILL BECOME MORE SWLY AND
THEN GUSTY IN THE AFTERNOON. GIVEN LITTLE CHANGE IN THE LARGE
SCALE FLOW PATTERN ALOFT AND WITH A WARM FRONT LIFTING NWD THROUGH
THE AREA LATER TODAY...THERE WILL BE CONTINUES CHANCES FOR
SHRA/TSRA OVER THE AREA THROUGH THE AFTERNOON AND INTO THE EVENING.
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN CATEGORICAL IFR/LIFR CONDITIONS INTO THE EARLY
MORNING HOURS. LOWER CONFIDENCE IN WHETHER THE IFR/LIFR WILL BE
CIGS OR VIS AS THEY WILL BOTH LIKELY BOUNCE AROUND.
* MEDIUM TO HIGH CONFIDENCE CHANCES FOR SCT SHRA/TSRA THROUGH THE
REMAINDER OF THE NIGHT AND INTO TOMORROW MORNING.
. LOW CONFIDENCE IN THE EXACT TIMING/EXTENT/LOCATION OF SHRA/TSRA.
* MEDIUM CONFIDENCE REGARDING WINDS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
* THURSDAY THROUGH MONDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA THROUGH THE PERIOD. BEST CHANCES
FOR TSRA APPEAR TO BE FRIDAY INTO THE WEEKEND. CMS
&&
.MARINE...
315 AM CDT
A SERIES OF LOW PRESSURE SYSTEMS WILL TRACK NORTHEAST FROM THE
PLAINS TOWARD HUDSON BAY OVER THE NEXT SEVERAL DAYS. A WEAK WARM
FRONT ACROSS CENTRAL ILLINOIS AND INDIANA WILL MOVE NORTHWARD
ACROSS THE LAKE TODAY...WITH GENERALLY SOUTHERLY FLOW SETTING UP
OVER THE LAKE. AN INCREASINGLY WARMER/MORE HUMID AIR MASS WILL
CONTINUE TO OVERSPREAD THE RELATIVELY COOLER WATERS...ALLOWING
AREAS OF FOG...POSSIBLY DENSE...TO DEVELOP OVER THE LAKE. WHILE
WINDS OVER THE LAKE WILL REMAIN BELOW 25KT FOR THE NEXT SEVERAL
DAYS...OCCASIONAL PERIODS OF THUNDERSTORMS WILL RESULT IN
OCCASIONALLY DISTURBED/ALTERED WIND FIELDS...WITH VARIABLE AND
POTENTIALLY MUCH STRONGER WINDS AROUND THUNDERSTORMS.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...NEARSHORE WATERS
UNTIL 10 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
105 AM CDT WED MAY 2 2012
.DISCUSSION...
935 PM CDT
SURFACE QUASI-WARM FRONT WAS ANALYZED ALONG THE SOUTHERN PERIPHERY
OF THE WFO LOT CWA THIS EVENING...HAVING BEEN SUPPRESSED BY
WELL-DEFINED MID-LEVEL VORT AND ASSOCIATED SURFACE WAVE THIS
AFTERNOON. EVENING WATER VAPOR IMAGERY INDICATES THIS MID-LEVEL
CIRCULATION IS NOW OVER INDIANA AND SOUTHERN LOWER MICHIGAN AND
MOVING AWAY FROM THE CWA...WITH THE AREA OF RAIN ASSOCIATED WITH
THIS FEATURE ALSO WEAKENING AND MOVING OUT OF THE AREA AT THIS TIME
WITH ONLY A FEW WEAK RADAR RETURNS LINGERING OVER FAR SOUTHERN LAKE
MICHIGAN AND PARTS OF THE EAST/SOUTHEAST CHICAGO METRO COUNTIES.
HAVE ADJUSTED POPS/WX GRIDS ACCORDINGLY...WITH LITTLE POTENTIAL FOR
ORGANIZED PRECIP ANTICIPATED THROUGH AT LEAST MIDNIGHT IN SUBSIDENT
WAKE OF DEPARTING MID-LEVEL VORT.
THE WARM FRONT IS STILL PROGGED TO LIFT NORTH OVERNIGHT...AND THEN
NORTH OF THE FORECAST AREA WEDNESDAY MORNING. SEVERAL FORECAST
CHALLENGES REMAIN FOR THE OVERNIGHT PERIOD HOWEVER...INCLUDING
STEADY/RISING TEMPERATURES WITH WARM FRONT...DEVELOPMENT OF PATCHY
DENSE FOG...AND THE POTENTIAL FOR RENEWED SHOWER AND THUNDERSTORM
DEVELOPMENT DURING THE LATE NIGHT HOURS.
GOES 11-3.9 MICRON IR IMAGERY INDICATES LOW STRATUS IN EASTERLY
LOW-LEVEL FLOW NORTH OF THE SURFACE WARM FRONT AT 02Z...WITH A FEW
NORTHERN IL LOCATIONS SUCH AS VYS DEVELOPING PATCHY DENSE FOG WHERE
SOME BREAKS HAVE FORMED ALONG THE SOUTHERN EDGE OF THE STRATUS DECK.
FARTHER NORTH...A SLOW LOWERING TREND HAS BEEN NOTED IN VISIBILITY
WITH AREAS OF 1-3SM FOG EXPECTED TO PERSIST DURING THE NIGHT WITH
IMPROVEMENT LIKELY FROM THE SOUTH AS WARM SECTOR SPREADS NORTH.
TEMPERATURES HAVE FALLEN INTO THE LOW/MID 50S ALONG THE LAKE
MICHIGAN SHORE...AND WILL LIKELY DIP TO THE UPPER 50S/AROUND 60
ELSEWHERE NORTH OF THE WARM FRONT AND INTO THE LOWER 60S FARTHER
SOUTH. TEMPERATURES WILL THEN LIKELY BECOME STEADY...AND EVEN RISE
LATE TONIGHT HOWEVER AS THE FRONT LIFTS NORTH.
AS FOR PRECIPITATION TRENDS...EXPECT SEVERAL HOURS OF DRY WEATHER AS
MENTIONED ABOVE. EVENING UPPER AIR ANALYSIS DOES INDICATE A 40 KT
MID-LEVEL SPEED MAX UPSTREAM OVER KANSAS THAT IS PROGGED TO
TRANSLATE NORTHEAST OVERNIGHT ALONG WITH A VERY MOIST WARM SECTOR
AIRMASS WITH H9 DEWPOINTS OF 16C NOTED UPSTREAM. SEVERAL RECENT RUNS
OF THE HRRR HAVE DEPICTED ELEVATED CONVECTION DEVELOPING ACROSS
SOUTHEAST IOWA AND MISSOURI THIS EVENING ALONG THE WARM FRONTAL ZONE
AND SPREADING INTO IL BY MIDNIGHT...AND WHILE DEEP MOIST CONVERGENCE
IS ANALYZED ALONG THE FRONT...SATELLITE AND RADAR TRENDS SUGGEST
THIS APPEARS TO BE OVER-FORECAST. A MORE LIKELY SCENARIO IS FOR MCS
OVER FAR SOUTHWESTERN MINNESOTA AND NORTHWEST IOWA TO PROPAGATE
EAST-SOUTHEAST ALONG THE FRONTAL ZONE AND EVENTUALLY WEAKEN AS IT
MOVES INTO THE FORECAST AREA DURING THE PRE-DAWN HOURS OF EARLY
WEDNESDAY.
RATZER
//PREV DISCUSSION...
304 PM CDT
CONCERNS FOR LATEST FORECAST PACKAGE WILL BE DEALING WITH ONGOING
CONVECTIVE CHANCES THROUGH THE WEEK...AS WELL AS IMPACT ON
TEMPERATURES.
TODAY...WELL DEFINED MCV FROM REMNANT MCC MOVING ACROSS CENTRAL
ILLINOIS WITH LINGERING SHOWERS ACROSS NORTHERN ILLINOIS AND
NORTHWEST INDIANA. THIS AFTERNOON...VERY MODEST MUCAPE (LESS THAN
100 J/KG) ACROSS PORTIONS OF NORTHERN ILLINOIS THIS AFTERNOON AND
LIFT ASSOCD WITH MCV PUSHING EAST ACROSS THE REGION WILL SUPPORT
ONGOING SHOWERS...BUT EXPECT THUNDER CHANCES TO BE FAIRLY LOW WITH
LIMITED INSTABILITY. ONCE THIS AREA OF PRECIP MOVES EAST...EXPECT A
DRY PERIOD THIS EVENING WITH SUBSIDENCE IN PLACE.
TONIGHT...SURFACE FRONT WILL LIFT NORTH OF THE REGION THIS EVENING
WITH SURFACE TEMPS/DEWPOINTS RISING INTO THE 60S OVERNIGHT. H5
HEIGHT RISES INITIALLY SHOULD INHIBIT ANY DEEP CONVECTION...HOWEVER
A WEAK IMPULSE MOVING EAST ACROSS IOWA WILL MOVE INTO NORTHERN
ILLINOIS AFTER MIDNIGHT TONIGHT AND 50 KT LOW LEVEL JET DEVELOPS OVER
EASTERN KANSAS/NORTHWEST MISSOURI EXTENDING INTO NORTHWESTERN
ILLINOIS. MAX THETA-E CONVERGENCE SETS UP OVER EASTERN IOWA/NORTHERN
ILLINOIS AS MUCAPE RISES TO NEAR 2000 J/KG. BELIEVE THIS WILL BE
BEST FOCUS FOR CONVECTION TONIGHT AND ADJUSTED POPS
ACCORDINGLY...WITH BEST CHANCES //LIKELY POPS// ACROSS
NORTH/NORTHEASTERN PORTIONS OF THE CWA AND TRAILING OFF SOMEWHAT TO
THE SOUTHWEST. AS FAR AS THE SEVERE THREAT TONIGHT...GIVEN THE
UNFAVORABLE DIURNAL TIMING...EXPECT MAINLY ELEVATED ACTIVITY NORTH
OF THE FRONT WITH A MARGINAL SEVERE THREAT GIVEN 30 KT OF DEEP LAYER
SHEAR AND SKINNY CAPE PROFILES.
WEDNESDAY AND WEDNESDAY NIGHT...MURKY SCENARIO PRESENTS ITSELF
WEDNESDAY AND WILL LIKELY HINGE ON COLD POOL/OUTFLOW DEVELOPMENT
FROM TONIGHTS CONVECTION. SYNOPTICALLY...WE SHOULD BE WELL INTO THE
WARM SECTOR WITH SOME GUIDANCE NOW SUGGESTING TEMPERATURES INTO THE
LOW 90S SOUTH OF I-80. WAS MORE CONSERVATIVE THAN THAT...BUT DID
BUMP UP TEMPERATURES SLIGHTLY FROM GOING FORECAST. VERY WEAK LAPSE
RATES BETWEEN 900-700MB AND MODEST INVERSION WILL HELP KEEP THE
ATMOSPHERE WEAKLY CAPPED...BUT STRONG INSTABILITY IS EXPECTED TO
DEVELOP WITH NAM INDICATING MLCAPE VALUES REACHING 3000 J/KG BY
WEDNESDAY AFTERNOON. MODELS DO NOT INDICATE ANY UPPER LEVEL SUPPORT
FOR LARGE SCALE ASCENT THIS FAR SOUTH AND MAIN UNCERTAINTY HINGES ON
OUTFLOW DEVELOPMENT PUSHING EFFECTIVE WARM FRONT FARTHER SOUTH AND
BECOMING FOCUS FOR DEVELOPMENT AS SUGGESTED BY 12Z LSX WRF AS WELL
AS THE 12Z NAM RUNS. MOST OTHER GUIDANCE SEEMS TO FOCUS ON AREAS
FARTHER NORTH. GIVEN HIGH DEGREE OF UNCERTAINTY...OPTED TO LEAVE
POPS AS THEY WERE...WITH LOW CHANCE POPS ACROSS THE NORTH AND SLIGHT
CHANCE ACROSS THE SOUTH. GIVEN THIS...THERE IS CONDITIONAL THREAT
FOR SEVERE WEATHER SHOULD THUNDERSTORMS DEVELOP. MODEST WESTERLIES
ALOFT WILL LEAD TO MARGINAL SHEAR...PARTICULARLY ACROSS NORTHERN
PORTIONS OF THE CWA....ALONG WITH THE STRONG INSTABILITY TO SUPPORT
ORGANIZED SEVERE WEATHER WITH MAIN THREATS BEING LARGE HAIL AND
DAMAGING WINDS. WEDNESDAY NIGHT...LOW LEVEL JET IS FORECAST TO
DEVELOP INTO EASTERN NEBRASKA INTO IOWA WITH MEAN DEEP LAYER FLOW
STEERING ANY RESULTANT DEVELOPMENT TO THE EAST-NORTHEAST.
AGAIN...CHANCES ARE BETTER NORTH OF THE CWA BUT WILL MAINTAIN SOME
LOW CHANCE POPS INTO THE NORTHERN PORTIONS OF ILLINOIS WEDNESDAY
NIGHT. STILL FIRMLY INTO THE WARM SECTOR WEDNESDAY NIGHT...EXPECT
TEMPERATURES TO REMAIN UNSEASONABLY WARM...STAYING PROPPED UP IN THE
MID 60S.
THURSDAY THROUGH FRIDAY...VERY SIMILAR SETUP THURSDAY AS COMPARED TO
WEDNESDAY WITH ONGOING ISSUES WITH BOUNDARY PLACEMENT. BY THURSDAY
NIGHT HOWEVER...FRONT MAKES A PUSH TO THE SOUTH ACROSS THE AREA WITH
BETTER CHANCES OF PRECIP ACROSS ILLINOIS AND INDIANA. GUIDANCE IN
FAIRLY DECENT TIMING FROPA EARLY FRIDAY. AS THE FRONT SWEEPS ACROSS
THE REGION...EXPECT TEMPERATURES TO QUICKLY FALL FRIDAY
EVENING...PARTICULARLY AREAS CLOSER TO THE LAKE.
EXTENDED FORECAST...SATURDAY THROUGH TUESDAY...FRONTAL BOUNDARY IS
EXPECTED TO STALL TO OUR SOUTH THEN LIFT BACK NORTH ON
SATURDAY...LINGERING ACROSS THE REGION THROUGH THE WEEKEND AND
BRINGING ADDITIONAL CHANCES FOR SHOWERS AND THUNDERSTORMS. THERE IS
A GREAT DEAL OF UNCERTAINTY REGARDING ANY PRECISE TIMING ON PRECIP
AS WELL AS SPECIFICS ON TEMPERATURES AND WHERE THE BAROCLINIC ZONE
SETS UP. SUNDAY FOR EXAMPLE...MODELS INDICATE A NEAR 20 DEGREE
SPREAD ACROSS THE CWA. GIVEN UNCERTAINTY...DID NOT STRAY FROM
BLENDED MODEL SOLUTION FOR THE EXTENDED PORTION OF THE FORECAST. BMD
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PERIODS OF IFR CIGS/VIS THROUGH THE EARLY MORNING HOURS.
* CHANCE FOR SCT SHOWERS/ISOLD THUNDERSTORMS DEVELOPING DURING THE
EARLY MORNING HOURS.
* GUSTY SOUTHWEST WINDS WEDNESDAY AFTERNOON.
KREIN
//DISCUSSION...UPDATED 06Z...
THE VERY SLOPPY WEATHER WILL CONTINUE FOR THE NRN IL/NWRN INDIANA
TERMINALS WITH MULTIPLE CONCERNS. FOR THE NEXT FEW HOURS...THE
FOCUS WILL BE ON CIGS/VIS. THE DENSER LOW STRATUS IS SHOWING SIGNS
OF SCATTERING...BUT AS THIS OCCURS...VISIBILITY SHOULD DROP. IN
GENERAL...LOCATIONS WITH IMPROVING CEILINGS SHOULD SEE VIS DROP TO
IFR/LIFR WHILE LOCATIONS WHERE THE IFR/LIFR CIGS
REMAIN...VISIBILITY SHOULD BE 2-3SM. ANY WAY YOU CUT
IT...CATEGORICALLY...THERE WILL BE WIDESPREAD IFR/LIFR CONDITIONS
ACROSS NRN IL/IN FOR THE NEXT SEVERAL HOURS.
SHRA/TSRA WILL INCREASINGLY BECOME A CONCERN THROUGH THE NIGHT AS
WELL. LATEST RADAR TRENDS SHOW SCT SHRA DEVELOPING NORTH OF THE
WARM FRONT...IN A ZONE OF STRENGTHENING WARM ADVECTION AND
ISENTROPIC LIFT OVER NRN IL. THIS SCT ACTIVITY IS WELL IN ADVANCE
OF THE SOLID LINE OF CONVECTION MOVING EWD THROUGH IOWA AND SRN
MN. WHILE THE TRENDS IN THE SHORT TERM FORECAST MODELS INDICATE
THAT THE SOLID LINE SHOULD BREAK UP AND WEAKEN THROUGH THE
REMAINDER OF THE NIGHT...WITH THE STRONGEST ACTIVE TS REMAINING
NORTH OF THE IL/WI BORDER...NOT REAL CONFIDENT IN THIS IDEA GIVEN
THE LATEST TRENDS OF STRENGTHENING OF THE LINE OVER WRN
IOWA...INVOF A DEVELOPING SFC WAVE. SO...WHILE HAVE MAINTAINED THE
IDEA OF SCT TS IN THE TAFS FOR THE EARLY MORNING HOURS...WILL
MONITOR CLOSELY TO SEE IF THE TS COVERAGE WILL NEED TO BE BOLSTERED.
FOR THE REMAINDER OF THE DAY...WINDS WILL BECOME MORE SWLY AND
THEN GUSTY IN THE AFTERNOON. GIVEN LITTLE CHANGE IN THE LARGE
SCALE FLOW PATTERN ALOFT AND WITH A WARM FRONT LIFTING NWD THROUGH
THE AREA LATER TODAY...THERE WILL BE CONTINUES CHANCES FOR
SHRA/TSRA OVER THE AREA THROUGH THE AFTERNOON AND INTO THE EVENING.
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN CATEGORICAL IFR/LIFR CONDITIONS INTO THE EARLY
MORNING HOURS. LOWER CONFIDENCE IN WHETHER THE IFR/LIFR WILL BE
CIGS OR VIS AS THEY WILL BOTH LIKELY BOUNCE AROUND.
* MEDIUM TO HIGH CONFIDENCE CHANCES FOR SCT SHRA/TSRA THROUGH THE
REMAINDER OF THE NIGHT AND INTO TOMORROW MORNING.
. LOW CONFIDENCE IN THE EXACT TIMING/EXTENT/LOCATION OF SHRA/TSRA.
* MEDIUM CONFIDENCE REGARDING WINDS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
* THURSDAY THROUGH MONDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA THROUGH THE PERIOD. BEST CHANCES
FOR TSRA APPEAR TO BE FRIDAY INTO THE WEEKEND. CMS
&&
.MARINE...
215 PM CDT
SERIES OF LOW PRESSURE SYSTEMS WILL TRACK NORTHEAST FROM THE PLAINS
TOWARD HUDSON BAY OVER THE NEXT SEVERAL DAYS. WEAK WARM FRONT SOUTH
OF THE LAKE TODAY WILL MOVE NORTHWARD ACROSS THE LAKE TONIGHT INTO
WEDNESDAY WITH GENERALLY SOUTHERLY FLOW OVER THE LAKE...MUTED
SOMEWHAT BY THE INCREASINGLY STABLE CONDITIONS AS WARMER/MORE HUMID
AIR MASS SPREADS NORTHWARD OVER THE COLD WATERS. THE HUMID AIR
INTERACTING WITH THE COLDER MARINE LAYER COULD RESULT IN AREAS OF
FOG...POSSIBLY DENSE AS HAS BEEN NOTED ALONG THE SOUTHWESTERN SHORES
OF THE LAKE THIS AFTERNOON. VERY LOW CONFIDENCE IN HOW BIG OF A
PROBLEM FOG WILL BECOME OVER THE OPEN LAKE SO WILL INCLUDE MENTION
OF FOG BUT HOLD OFF ON A MARINE FOG ADVISORY FOR OPEN WATERS. A
COUPLE OF THUNDERSTORM COMPLEXES WILL LIKELY MOVE ACROSS THE LAKE
THE NEXT SEVERAL DAYS RESULTING IN OCCASIONALLY DISTURBED/ALTERED
WIND FIELDS...WITH VARIABLE AND POTENTIALLY MUCH STRONGER WINDS
AROUND THUNDERSTORMS.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...NEARSHORE WATERS
UNTIL 10 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1133 PM CDT TUE MAY 1 2012
.DISCUSSION...
ISSUED 845 PM CDT TUE MAY 1 2012
WARM FRONT HAS LIFTED NORTH OF PIA AND BMI EARLY THIS EVENING AND
EXPECT THE BOUNDARY TO SLOWLY MAKE ITS WAY NORTHWARD OVERNIGHT.
THE STRONG TO SEVERE CONVECTION WHICH DEVELOPED ALONG THE WARM
FRONT LATE THIS AFTERNOON HAS SHIFTED WELL EAST OF THE AREA. MAIN
THREAT FOR ORGANIZED CONVECTION WILL BE ALONG A COLD FRONT TO OUR
NORTHWEST...OVER PARTS OF MINNESOTA INTO NW IOWA. SOME OF THE HI-RES
CONVECTIVE ALLOWING MODELS SUGGEST THE CONVECTION TO OUR WEST MAY
MAKE IT INTO THE WEST AND NORTHWEST PORTION OF THE AREA BY DAWN
WEDNESDAY. HIGHEST CHANCE POPS IN GRIDS THIS EVENING WILL CONTINUE
TO BE ACRS THE NORTH...CLOSER TO THE WARM FRONT...AND THEN OVERNIGHT
OVER THE FAR NORTH AND WEST WITH THE POSSIBILITY OF THE PLAINS
CONVECTION MAKING IT INTO OUR AREA BY DAWN. CURRENT FORECAST HAS
THESE TRENDS WELL HANDLED THIS EVENING...AS A RESULT...NO UPDATE
WILL BE NEEDED.
&&
.AVIATION...
ISSUED 1125 PM CDT TUE MAY 1 2012
LITTLE CHANGE FROM PREVIOUS DISCUSSION...THE MAIN FORECAST CONCERNS
WILL BE WITH COVERAGE OF FOG OVERNIGHT AND CHANCES FOR CONVECTION
ACRS THE NORTHERN TAF SITES BY MORNING. FRONTAL BOUNDARY HAS EDGED
BACK SOUTH INTO CENTRAL IL BUT SHOULD START TO PUSH BACK NORTH
AFTR 08Z AS THE LOW LEVEL SOUTHERLY FLOW INCREASES AHEAD OF THE
NEXT WEATHER SYSTEM OUT ACRS THE MISSOURI VALLEY THIS EVENING.
WILL CONTINUE WITH MAINLY MVFR VSBYS IN FOG AS THE OVERALL TRENDS
EARLY THIS EVENING HAVE BEEN FOR SOME RATHER VARIABLE VSBYS NORTH
OF THE FRONTAL BOUNDARY. WITH THE FRONT EXPECTED TO PUSH BACK NORTH
LATE TONIGHT...WINDS SHOULD INCREASE ENOUGH TO KEEP THE FOG FROM
BECOMING TOO DENSE/WIDESPREAD. AS FAR AS RAIN CHANCES...THE CONVECTION
OVER NORTHERN IOWA IS TAKING MORE OF A SE TRACK AND THAT TREND SHOULD
CONTINUE...HOWEVER...WE STILL EXPECT A WEAKENING TREND TO OCCUR BEFORE
THE CONVECTION APPROACHES THE MISSISSIPPI RIVER BY MORNING.
SURROUNDING VAD WIND PROFILES CONTINUE TO SHOW WINDS AT THE 1500-2000
FOOT LEVEL WERE INCREASING AND FORECAST MODELS SUGGEST THIS TREND
WILL CONTINUE OVERNIGHT. AS A RESULT...WILL NEED TO INCLUDE LOW LEVEL
WIND SHEAR AFTR 06Z AT PIA AND SPI...AND AFTR 09Z FOR THE REMAINDER
OF THE FORECAST SITES WITH SW WINDS EXPCTD TO REACH 45 KTS AT 2000
FEET. SFC WINDS ARE EXPECTED TO INCREASE WEDNESDAY MORNING WITH
GUSTS UP TO 25 KTS AT TIMES OUT OF THE SOUTH TO SOUTHWEST.
SMITH
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT TUE MAY 1 2012
A WET BIAS IS INDICATED IN ALL OF THE DETERMINISTIC MODELS AS A
FRONTAL BOUNDARY LIFTS NORTH AS A WARM FRONT TONIGHT...THEN LINGERS
JUST W-NW OF ILLINOIS FOR MUCH OF THE WEEK BEFORE RETURNING AS A
COLD FRONT LATER IN THE WEEKEND. A WARM AND HUMID AIRMASS WILL
DEVELOP OVER C IL TOMORROW BEHIND THE WARM FRONT. THAT SUMMER-
TIME TYPE OF AIRMASS WILL BE RIPE FOR ANY UPPER SHORTWAVES AND
LINGERING SURFACE BOUNDARIES TO BECOME ACTIVE WITH STORMS WHEN ANY
ELEVATED MIXED LAYERS BECOME UNSTABLE ENOUGH FOR SUSTAINED
UPDRAFTS. THE END RESULT IS AN ABUNDANCE OF PRECIP CHANCES
PEPPERED THROUGHOUT THE NEXT 7 DAYS...BUT CONFIDENCE ON RAIN/STORM
COVERAGE IN GENERAL IS LOW.
SHORT TERM...TONIGHT THROUGH THURSDAY.
THE WARM FRONT IS CURRENTLY EXTENDING FROM LOW PRESSURE NEAR
FULTON COUNTY TO THE SE TOWARD TERRE HAUTE. AN MCV ASSOCIATED WITH
THE SURFACE LOW WILL HELP TRIGGER ADDITIONAL SHOWERS AND A FEW
STORMS ACROSS THE NORTH INTO THE EVENING. ADDITIONAL STORMS WILL
BE POSSIBLE ACROSS THE SOUTH INTO THE EVENING AS THE SOUTHERN
PERIPHERY OF THE MCV REMAINS ACTIVE WHERE SUNSHINE WAS MORE
PLENTIFUL TODAY. WE KEPT SLIGHT CHANCE POPS IN ALL AREAS TONIGHT
TO ACCOUNT FOR VARIOUS CONVECTIVE ELEMENTS THAT MAY FESTER UNDER
THE ADVANCING WARM FRONT IN THE NORTH AND THE POST MCV AIRMASS IN
THE SOUTH.
IN OUR COUNTIES...WEDNESDAY SHOULD BE CAPPED WITH WARM AIR ALOFT
FOR MOST OF THE DAY. OUR NORTHERN COUNTIES ARE IN THE DAY 2
SLIGHT RISK FOR SEVERE STORMS...CLOSER TO THE LINGERING WARM
FRONT. THE HRRR MODEL IS SHOWING AN ADVANCING STORM COMPLEX LATER
TONIGHT ACROSS MN/IA. THAT SYSTEM MAY PUT DOWN AN ADDITIONAL
BOUNDARY FROM THE COLD POOL THAT DRIFTS EAST TOWARD IL WED
MORNING. IT MAY BECOME ACTIVE AS PEAK HEATING CREATES SURFACE
BASED INSTABILITY. EVEN IF MORNING CLOUDS AND FOG LINGER IN THAT
AREA THROUGH THE MORNING...ANY EARLY AFTERNOON CLEARING WILL
ALLOW FOR RAPID DESTABILIZATION OF THE AIRMASS IN FAR NW IL AND
AREAS TO THE W-NW NEAR THE WARM FRONT. IF THE CAP BREAKS TO THE
NW...THE STORMS MAY MAINTAIN SEVERE LEVELS INTO SOME OF OUR
COUNTIES...BUT THE FARTHER E-SE THEY PROGRESS INTO THE CAPPED
AIRMASS...THEY SHOULD LOSE SOME STRENGTH. THEREFORE WE ONLY HAVE
SLIGHT CHANCE POPS IN OUR NORTHERN COUNTIES WED/WED NIGHT.
THURSDAY MAY BE A SIMILAR SCENARIO TO WEDNESDAY...AS THE WARM
FRONT/STATIONARY FRONT REMAINS IN PLACE TO OUR NW. OUR NW COUNTIES
ARE IN THE DAY 3 SLIGHT RISK FOR SEVERE STORMS AGAIN AS A RESULT.
NEAR RECORD HIGHS IN THE MID TO UPPER 80S ARE EXPECTED WED AND
THUR AS DEWPOINTS CLIMB INTO THE MID 60S. IT WILL BE AN
UNCOMFORTABLE AIRMASS AFTER THE RELATIVELY COOLER PORTIONS OF
APRIL.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY.
STORM CHANCES WILL INCREASE FROM NW TO SE ON THURSDAY NIGHT AS LOW
PRESSURE MOVES FROM THE DAKOTAS INTO THE GREAT LAKES...DRAGGING A
COLD FRONT TOWARD NW IL. STORM CHANCES WILL CONTINUE FRI AND FRI
NIGHT AS THE FRONT STALLS OUT ACROSS SOUTH CENTRAL IL. SATURDAY
MAY SEE A BREAK IN THE ACTION BUT SLIGHT CHANCES WILL CONTINUE DUE
TO THE PROXIMITY OF THE FRONT AND 500MB SHORTWAVES.
HIGHER CHANCES OF SHOWERS AND STORMS WILL DEVELOP LATER SUNDAY
INTO MONDAY AS THE NEXT LOW PRESSURE CENTER MOVES FROM THE CENTRAL
PLAINS INTO C IL ALONG THE FRONT. A COOLER AIRMASS WILL TRY TO
DROP SOUTH INTO OUR PORTION OF IL ON MONDAY NIGHT AND TUESDAY...AS
HIGH PRESSURE FROM CANADA BUILDS SOUTHWARD. SO WE WENT WITH A
COOLING TREND FOR MON AND TUES...WITH TUES HIGHS REMAINING IN THE
60S.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 9 AM CDT WEDNESDAY FOR ILZ051.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
332 PM EDT WED MAY 2 2012
.SHORT TERM...
PRIND W/VRY RECENT CONV DVLP OVER ERN IL SIMILAR IN KIND W/SHRT TERM
RUC TRENDS ALTHOUGH STILL WAITING FOR CONVN ACRS LK HURON TO DVLP
SWD INTO GROWING INSTABILITY RESERVOIR. REGARDLESS NR TERM GUIDANCE
OFFERS A SIMILAR AND COMPELLING SIGNAL LT THIS AFTN AND EVENING
W/CONVN XPCD INVOF OF OLD OUTFLW BNDRY STRETCHING FM WRN IN NEWD
INTO NW OH OR MORE LIKELY WITHIN DVLPG CONFLUENCE ZONE FM THE MI
THUMB SWWD INTO NRN IN AND ALG TAIL END OF SW TROUGH CROSSING
THROUGH ERN LK SUPERIOR ATTM. PRIOR UPDATE POPS GRIDS FM THIS MORNING
HIGHLITE ERN AREAS AND WILL CONT THAT IN PLACE LT THIS AFTN BFR
SHIFTING IT SWD THIS EVENING. OTHERWISE MORE SIG LLJ RESPONSE XPCD
TO DVLP AFT DARK ORIENTED FVRBLY INTO RETREATING OFB. GIVEN
CONCURRENCE OF HIGHRES GUIDANCE ON SHARP THETA-E RIDGE PLACEMENT
OVERNIGHT WILL CONT TO HOLD FAR SRN AREAS OUT OF ANY MENTIONABLE
POP ALG PERIPHERY OF MID LVL HGT RISES.
MORE UNCERTAIN FCST ON THU IN LIGHT OF POTENTIAL UPSTREAM MESOSCALE
DVLPMNTS OVERNIGHT YET BUY INTO THE WRF IDEA OF ANOTHER STG-SVR MCS
RIDING OUT OF IA TOMORROW MORNING AND ANOTHER OFB TO DEAL W/BY AFTN
OVR NW ZONES IN THE LEAST. OTHERWISE VRY WARM TEMPS XPCD W/LL
THERMAL RIDGE IN PLACE.
&&
.LONG TERM...FRIDAY THROUGH WEDNESDAY
BROAD UPPER RIDGING WILL DAMPENED BY SEVERAL SMALLER SCALE VORTICES
PROGRESSING THROUGH MID/UPPER FLOW TO BEGIN THE PERIOD. GUIDANCE
CONTINUES TO EXHIBIT SOME DECENT AGREEMENT IN THE STRONGEST OF THESE
SHORT WAVES...LIKELY CONVECTIVELY ENHANCED...APPROACHING THE AREA
DURING THE MORNING HOURS. VEERING LOW LEVEL JET NOSING INTO LOCAL
AREA BY MORNING AND ENHANCED LOW/MID LEVEL THETAE MOISTURE
ADVECTION/CONVERGENCE ASSOCIATED WITH THIS JET SUGGESTS A
POSSIBILITY OF REMNANTS OF OVERNIGHT MCS AFFECTING THE AREA. THIS
RAISES CONVECTIVE CONCERNS ON FRIDAY IN TERMS OF POSITIONING OF
EFFECTIVE FRONTAL BOUNDARY. SYNOPTIC FRONTAL BOUNDARY SHOULD BE
DROPPING BACK SOUTHWARD DURING THE DAY...BUT CONCERN IS THAT
EFFECTIVE OUTFLOW FROM POSSIBLE MORNING MCS MAY TAKE THE EFFECTIVE
BOUNDARY FURTHER SOUTH AND POSSIBLY FOCUS SOUTHERN AREAS FOR GREATER
AFTERNOON CONVECTIVE POTENTIAL. SEVERE POTENTIAL SOMEWHAT UNCLEAR AT
THIS TIME WITH AFOREMENTIONED CONCERNS. HOWEVER...MODERATE
INSTABILITY POSSIBLE ONCE AGAIN SOUTH OF THE EFFECTIVE BOUNDARY WITH
SOME ENHANCEMENT IN DEEP LAYER SHEAR EXPECTED IN ASSOCIATION WITH
THIS UPPER VORT MAX.
MID/UPPER LEVEL RIDGING TO BUILD BACK INTO THE AREA FRIDAY NIGHT
WITH SFC BOUNDARY BECOMING NEARLY STATIONARY ACROSS THE OHIO RIVER
VALLEY. A MORE AMPLIFIED UPPER LEVEL TROUGH WILL MOVE INTO THE
WESTERN CONUS FRIDAY NIGHT WITH RENEWED LEE CYCLOGENESIS ON
SATURDAY. THIS WILL SET THE STAGE FOR THE POSSIBILITY OF EPISODES OF
STRONGER WARM ADVECTION/OVERRUNNING TYPE FORCING FOR THE WEEKEND
WITH BEST CHANCE OF THUNDER ACROSS APPROXIMATELY SOUTHWEST HALF OF
CWA WHERE ELEVATED INSTABILITY WOULD BE SLIGHTLY MORE ENHANCED IN
THIS SETUP AND HAVE MAINTAINED LOW TO MID RANGE CHANCE POPS THROUGH
THE WEEKEND. TEMPERATURES SHOULD REMAIN FAIRLY MILD HOWEVER WITH
BRUNT OF LOW LEVEL COLD AIR REMAINING ACROSS NORTHERN GREAT LAKES
INTO SOUTHEAST CANADA.
FOR MON TO WED...12Z GFS HAS BECOME MORE INLINE WITH RECENT EC
TRENDS IN MORE OF A SPLIT FLOW TYPE PATTERN BECOMING ESTABLISHED
EARLY IN THE WEEK...WITH A MORE PROGRESSIVE AND LARGER SCALE
NORTHERN PLAINS/SOUTH CENTRAL CANADIAN UPPER TROUGH. PROGRESSION OF
THIS TROUGH SHOULD ALLOW SFC REFLECTION TO TRACK SOUTH OF THE AREA
AND ENHANCE PRECIP POTENTIAL AGAIN LATE SUNDAY NIGHT INTO
MONDAY...BEFORE CONDITIONS DRY OUT MONDAY NIGHT/TUESDAY. GIVEN TREND
IN MEDIUM RANGE MODELS TOWARD THIS GENERAL IDEA...HAVE INTRODUCED
POPS FOR MONDAY/MONDAY NIGHT WITH REMAINDER OF FORECAST KEPT DRY AS
SFC ANTICYCLONE SHIFTS EAST OUT OF THE PLAINS. TEMPERATURES ARE
EXPECTED TO COOL BACK TOWARD SEASONABLE NORMALS FOR TUE/WED.
&&
.AVIATION...
VFR CONDS XPCD THROUGH THE PD. PD OF MVFR CONDS ASSOCD/W CONVN
REMAINS ENTIRELY PSBL YET LT THIS AFTN AND EVENING YET MOST
UNCERTAIN AND HELD CLOSE W/PRIOR VCTS MENTION AT BOTH TERMINALS
GIVEN COLLABORATING RUC GUIDANCE.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...T
LONG TERM...MARSILI
AVIATION...T
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
134 AM EDT WED MAY 2 2012
.AVIATION.../06Z TAFS/
AREA OF SHRA/TS IN COMMA HEAD OF MCV HAD MOVED EAST OF NRN INDIANA
EARLY THIS MORNING. WAVY SFC WARM FRONT REMAINS SOUTH OF THE AREA
ACROSS CENTRAL IL/IN. THIS FRONT IS EXPECTED TO LIFT SLOWLY NORTH
OVERNIGHT AND THEN PRBLY INCREASE IN SPEED AS STRONGER S-SW WINDS
ALOFT MIX DOWN TO THE SURFACE DURING THE DAY. SOME STRATUS AND FOG
WITH OCNL IFR CONDITIONS EXPECTED AT THE TERMINALS THROUGH THE EARLY
MORNING HOURS. CONDITIONS SHOULD IMPROVE TO VFR BY LATE MORNING.
POTENTIAL FOR MORE TSTMS AT THE TERMINALS OVERNIGHT IS LOW... BUT
NOT ZERO AS LOW LEVEL WAA/ISENT LIFT CONTS ACROSS THE AREA. LEFT
VCTS/CB IN FCST FOR LATE AFTN AS SOME POTENTIAL FOR ONGOING STORMS
OVER WRN IA/ERN NEB TO HOLD TOGETHER TODAY AND MOVE INTO DESTABILIZING
AIRMASS OVER OUR AREA.
&&
.PREV DISCUSSION... /ISSUED 845 PM EDT TUE MAY 1 2012/
UPDATE...
MADE ONLY MINOR TWEAKS TO NEAR TERM GRIDS WRT TEMPS AND POPS.
ADJUSTED TEMPS TO BETTER MATCH RECENT OBS AND TREND THROUGH THE
OVERNIGHT. REDUCED POPS FROM SOUTHWEST TO NORTHEAST AFTER 03Z AS
THE MCV OVER NORTHERN ILLINOIS SHOULD PULL THE WARM FRONT THROUGH
OUR REGION AND USHER DRIER CONDITIONS INTO MUCH OF THE FORECAST
AREA. REDUCED EMPHASIS OF THUNDER IN THE VERY NEAR TERM...BUT KEPT
THUNDER MENTION IN FOR THE OVERNIGHT AS SOME ELEVATED INSTABILITY
AND A STRENGTHENING LLJ COULD SPAWN A FEW THUNDERSTORMS ALONG THE
WARM FRONT THROUGH THE OVERNIGHT HOURS....ESPECIALLY ALONG THE
SOUTHERN TIER OF THE CWA WHERE STRONGEST MUCAPE EXISTS.
PREV DISCUSSION... /ISSUED 319 PM EDT TUE MAY 1 2012/
SHORT TERM...
MANY ISSUES TO SORT OUT IN THE SHORT TERM. MCV MOVING ACROSS THE
REGION TODAY HAS BEEN HANDLED BEST BY HRRR WITH OTHER HI RES
GUIDANCE IN BALLPARK BUT NOT NEAR AS FAST MOVING THIS WAVE
NORTHEAST. HAVE FOLLOWED HRRR FOR GUIDANCE IN THE SHORT TERM. SHOULD
SEE BULK OF PCPN MOVE EAST BEFORE 00Z WITH LINGERING SHOWERS AND FEW
THUNDERSTORMS FAR EAST AFTER 00Z. MEANWHILE...SOME DEVELOPMENT
POSSIBLE SOUTH OF MCV TRACK IN AREA OF INCREASING INSTABILITY LATE
THIS AFTERNOON WHICH COULD MOVE THROUGH CENTRAL AND NORTHERN AREAS
THIS EVENING. PREVIOUS GRIDS HAD LIKELY POPS ALL NIGHT AND THIS
SEEMS OVERDONE GIVEN FASTER ARRIVAL OF MCV AND INCREASING STABILITY
OVERNIGHT. HAVE ADJUSTED GRIDS FOR HIGHER POPS THIS EVENING BUT KEPT
CHANCE POPS OVERNIGHT WITH BOUNDARY IN THE AREA.
NEXT ISSUE IS WITH DEVELOPMENT OF AN MCS OVERNIGHT TO OUR NW AND
TRACK IT WOULD TAKE TOWARD DAYBREAK. NAM12 BRINGS SOUTHERN FRINGE OF
THIS SYSTEM ACROSS NORTHERN AREAS AROUND 12Z WITH GFS SIMILAR. HI
RES WRF NMM ALSO HINTS AT NORTHERN AREAS BEING BRUSHED BY CONVECTION
EARLY WED MORNING. THIS WARRANTS A SLIGHT NUDGE IN POPS EARLY
WEDNESDAY BUT CONFINED TO MID CHANCE RANGE GIVEN MCS UNCERTAINTY.
NAM AND WRF LAY A BOUNDARY OUT ACROSS CENTRAL CWA WEDNESDAY WHICH
THEN CONVECTS IN THE AFTERNOON WITH GROWING INSTABILITY. THIS
INSTABILITY IS CONTINGENT ON CLOUDS BREAKING UP AND AFTERNOON
HEATING BUT WITH SYNOPTIC WARM FRONT WELL NORTH AND STRONG SOUTHWEST
FLOW ALOFT THIS LOOKS PLAUSIBLE. RESULT WOULD BE TSRA DEVELOPMENT
FARTHER SOUTH IN CENTRAL CWA SO HAVE BROUGHT POPS BACK INTO THIS
AREA FOR THE AFTERNOON HOURS. SEVERE THUNDERSTORMS WOULD BE POSSIBLE
GIVEN MARGINAL BULK SHEAR BUT POTENTIALLY LARGE MUCAPE AND HIGH PWAT
VALUES.
TEMPS WILL BE VERY TRICKY WITH VERY WARM AND HUMID AIRMASS IN PLACE
BUT CONVECTIVE DEBRIS AND PCPN LIMITING FACTORS FOR MAX HEATING. ALL
BLEND USED FOR TEMPERATURES THROUGH THE SHORT TERM PERIOD AS THEY
ARE A NICE COMPROMISE BUT CERTAINLY COULD BE A LITTLE WARMER OR
COOLER DEPENDING ON AMOUNT OF SUN.
LONG TERM...THURSDAY THROUGH MONDAY
PERIOD TO BEGIN WITH SUBTLE HEIGHT RISES ACROSS THE UPPER
MIDWEST/NORTHERN GREAT LAKES AS MORE SIGNIFICANT SHORT WAVE UPPER
TROUGH AXIS TRACKS INTO THE PACIFIC NORTHWEST. THIS WILL RESULT IN
WARM FRONT TO CONTINUE TO SURGE NORTHWARD ACROSS THE GREAT LAKES
REGION ON THURSDAY. GENERALLY CAPPED CONDITIONS ARE ANTICIPATED
ACROSS APPROXIMATELY SOUTHERN TWO THIRDS OF THE FORECAST AREA WITH
MAIN QUESTION ON PRECIP CHANCES ACROSS THE FAR NORTH WHERE CAP WILL
LIKELY BE WEAKER. DIFFICULT AT THIS FORECAST DISTANCE TO LATCH ONTO
STRONGER PERIODS OF MID/UPPER LEVEL FORCING WITH MAIN SHORT WAVE
TRACK REMAINING WITH STRONGER BELT OF WESTERLIES FROM THE NORTHERN
PLAINS INTO THE UPPER GREAT LAKES. SEE NO REASON TO DEVIATE FROM
PREVIOUS FORECAST AT THIS TIME WITH LATE AFTERNOON LOW CHANCE TSRA
POPS ACROSS THE FAR NORTH GIVEN AFOREMENTIONED THERMODYNAMIC
PROFILES.
THE MORE PRONOUNCED PACIFIC WAVE IS THEN EXPECTED TO TRACK ACROSS
SOUTHWEST ONTARIO BY THURSDAY NIGHT INTO FRIDAY EVENTUALLY ALLOWING
COLD FRONT TO SHIFT EASTWARD. STRONGER FRONTAL CONVERGENCE MAY BE
CONFINED TO AREAS FURTHER NORTH ACROSS THE GREAT LAKES IN CLOSER
PROXIMITY TO STRONGER UPPER FORCING. HOWEVER WITH MODERATE
INSTABILITY PRECEDING THE FRONT WILL CONTINUE WITH MID RANGE
CHANCE POPS THURSDAY NIGHT THROUGH FRIDAY ACROSS ENTIRE FORECAST
AREA. SEVERE POTENTIAL STILL UNCLEAR FOR THURSDAY NIGHT/FRIDAY DUE
TO UNCERTAINTIES REGARDING UPSTREAM CONVECTION AND IMPACTS ON
INSTABILITY FOR THE LOCAL AREA ALONG WITH WHAT SHOULD BE MORE
MARGINAL DEEP LAYER SHEAR PROFILES FOR THIS PERIOD. NO SIGNIFICANT
CHANGES MADE TO VERY WARM TEMPERATURES IN ADVANCE OF THE FRONT
THURSDAY AFTERNOON WITH HIGHS IN THE MID TO UPPER 80S.
ON SATURDAY...ELONGATED SFC RIDGE AXIS TO BUILD INTO GREAT LAKES
REGION BEHIND THIS BOUNDARY...WITH SLIGHTLY MORE STABLE CONDITIONS.
PRECIP CHANCES ARE BECOMING MORE MUDDLED WITH BETTER ISENTROPIC
UPGLIDE OVER BOUNDARY POSSIBLY REMAINING JUST WEST OF THE AREA
ACROSS MID MS RVR VALLEY. CANNOT DISCOUNT ISOLD/SCT SHRA/TSRA
HOWEVER DUE TO PERSISTENT ELEVATED INSTABILITY. PERHAPS A SLIGHTLY
BETTER CHANCE FOR LATE SUNDAY/SUNDAY EVENING WHEN MID LEVEL RIDGE
IS EXPECTED TO SHIFT SLIGHTLY EASTWARD ACROSS CENTRAL CONUS IN
RESPONSE TO NEXT EASTERN PACIFIC WAVE MOVING ACROSS THE NORTHERN
ROCKIES. HOWEVER...BY LATE WEEKEND/EARLY NEXT WEEK MODEL
DETERMINISTIC/ENSEMBLE SPREADS BECOME MUCH MORE PRONOUNCED WITH
THIS NEXT PACIFIC WAVE. ALSO SIGNIFICANT VARIABILITY EXISTS WITH
EASTERN CANADIAN TROUGH THAT WILL IMPACT TRACK OF UPSTREAM PACIFIC
SYSTEM. GIVEN THESE UNCERTAINTIES...HAVE LOWERED CR ALLBLEND LOW
POPS TO BELOW MENTIONABLE LEVELS AND WILL KEEP MON/TUE DRY AT THIS
TIME.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...LASHLEY
LONG TERM...MARSILI
AVIATION...JT
UPDATE...BENTLEY
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
959 PM EDT THU MAY 3 2012
.SYNOPSIS...
A COLD FRONT, COMING SOUTHEAST FROM MICHIGAN, WILL BRING NUMEROUS
THUNDERSTORMS LATE FRIDAY FOLLOWED BY DRY, PLEASANT CONDITIONS
THIS WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
BLEND OF RECENT SATELLITE AND HRRR AND NAM MODEL OUTPUT CONTINUE
TO SHOW GULF MOISTURE ADVECTING INTO THE UPPER OHIO VALLEY FROM
KENTUCKY OVERNIGHT. EARLIER MODEL OUTPUT HAD SUGGESTED A BAND OF
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS DEVELOPING ALONG THE
LEADING EDGE OF THIS MOISTURE INFLUX, BUT MORE RECENT HRRR MODEL
OUTPUT SHOWS LESS CHANCE. AT THIS JUNCTURE HAVE MAINTAINED A SLIGHT
CHANCE OF SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS AREAS SOUTH
OF THE I-70 CORRIDOR AND PERHAPS FURTHER NORTH ALONG THE MOUNTAINS
LATE TONIGHT.
CONCUR WITH SREF MODEL OUTPUT, THAT THUNDERSTORMS CAN BECOME
NUMEROUS LATE FRIDAY AFTERNOON AND EVENING, DUE TO INCREASED
INSTABILITY RESULTING FROM DAYTIME HEATING AND THE INCREASED
SURFACE LAYER MOISTURE, PLUS PREFRONTAL CONVERGENCE AND LIFT
ASSOCIATED WITH THE COLD FRONT FROM MICHIGAN MOVING SOUTHEASTWARD
THROUGH THE UPPER OHIO VALLEY.
DESPITE THE POTENTIAL LARGE INSTABILITY, CONCUR WITH SPC THINKING
THAT THE RISK OF SEVERE STORM DEVELOPMENT WILL BE CONSTRAINED BY A
LACK OF DEEP VERTICAL SHEAR.
FORECASTED TEMPERATURES TO BE 15 TO 20 DEGREES WARMER THAN NORMAL
AS SUGGESTED BY RECENT GFS AND NAM MOS AND HRRR MODEL OUTPUT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
RECENT SREF MODEL OUTPUT CONTINUES TO SHOW UPPER LEVEL RIDGE
BUILDING ACROSS THE UPPER MIDWEST, WHICH WILL PROVIDE THE UPPER
OHIO VALLEY WITH A DRY, STABLE NORTHWEST FLOW THIS WEEKEND.
LIKEWISE TEMPERATURES WILL BE PLEASANT, WITH LOWS AND HIGHS NO
MORE THAN 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
EXTENDED PERIOD STARTS WITH GFS AND ECMWF IN FAIRLY GOOD AGREEMENT
WITH DEVELOPING CLOSED UPPER LEVEL LOW IN SOUTH CENTRAL CANADA AND A
WELL DEFINED RIDGE EXTENDING OVER THE GREAT LAKES.
AN UPPER LEVEL SHORTWAVE AHEAD OF THE CLOSED LOW WILL BRING THE
CHANCE FOR PRECIPITATION MONDAY AND TUESDAY. MODEL SOLUTIONS THEN
DIVERGE ON TIMING AND INTENSITY OF THE UPPER LOW AS IT DIVES
SOUTHWARD OVER THE GREAT LAKES FOR THE LATTER HALF OF THE WEEK.
THUS...KEPT A PERSISTENCE FORECAST OF CHANCE POPS THROUGH
MIDWEEK. EXPECT TEMPERATURES TO BE SLIGHTLY ABOVE NORMAL FOR THE
FIRST HALF OF THE WEEK MODERATING TO NEAR NORMAL AS UPPER LOW
CROSSES THE GREAT LAKES BY THE END OF THE WEAK.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL ALLOW FOR MOSTLY VFR CONDITIONS TO PREVAIL ACROSS
THE TERMINALS. THERE IS A SLIGHT CHANCE THAT AN ISOLATED SHOWER OR
THUNDERSTORM COULD DEVELOP OVERNIGHT, ALTHOUGH CHANCES ARE TOO LOW
TO MENTION IN THE TAFS. WITH WINDS BECOMING NEAR CALM OVERNIGHT,
THE LAMP SUPPORTS THE POTENTIAL FOR RADIATION FOG TO DEVELOP NEAR
DAWN AT KZZV/KFKL/KDUJ.
VFR CONDITIONS WILL PREVAIL EARLY ACROSS THE TERMINALS ON FRIDAY.
SHOWERS AND THUNDERSTORMS WITH RESTRICTIONS WILL BE LIKELY TOMORROW
AFTERNOON AND EVENING AS A COLD FRONT DROPS SOUTHWARD ACROSS THE
AREA.
.OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
THE CHANCE OF THUNDERSTORMS WILL CONTINUE FRIDAY NIGHT AS THE COLD
FRONT IS SLOW TO DROP SOUTHWARD. VFR CONDITIONS WILL PREVAIL FOR THE
WEEKEND AS HIGH PRESSURE PASSES TO THE NORTHEAST. THE NEXT COLD
FRONT WILL RETURN THE CHANCE OF SHOWERS AND THUNDERSTORMS MONDAY
INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
714 PM EDT THU MAY 3 2012
.SYNOPSIS...
A COLD FRONT, COMING SOUTHEAST FROM MICHIGAN, WILL BRING NUMEROUS
THUNDERSTORMS LATE FRIDAY FOLLOWED BY DRY, PLEASANT CONDITIONS
THIS WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
BLEND OF RECENT SATELLITE AND HRRR AND NAM MODEL OUTPUT SHOW
INCREASING MOISTURE ADVECTING INTO THE UPPER OHIO VALLEY FROM
KENTUCKY TONIGHT. MODEL OUTPUT ALSO SUGGESTS A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS AREAS SOUTH OF THE
I-70 CORRIDOR AND PERHAPS FURTHER NORTH ALONG THE MOUNTAINS LATE
TONIGHT.
CONCUR WITH SREF MODEL OUTPUT, THAT THUNDERSTORMS CAN BECOME
NUMEROUS LATE FRIDAY AFTERNOON AND EVENING, DUE TO INCREASED
INSTABILITY RESULTING FROM DAYTIME HEATING AND THE INCREASED
SURFACE LAYER MOISTURE, AND LIFT ASSOCIATED WITH THE COLD FRONT
FROM MICHIGAN MOVING SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY.
DESPITE THE POTENTIAL LARGE INSTABILITY, THE RISK OF SEVERE
STORM DEVELOPMENT WILL BE CONSTRAINED BY A LACK OF DEEP VERTICAL
SHEAR.
FORECASTED TEMPERATURES TO BE 15 TO 20 DEGREES WARMER THAN NORMAL
AS SUGGESTED BY RECENT GFS AND NAM MOS AND HRRR MODEL OUTPUT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
RECENT SREF MODEL OUTPUT CONTINUES TO SHOW UPPER LEVEL RIDGE
BUILDING ACROSS THE UPPER MIDWEST, WHICH WILL PROVIDE THE UPPER
OHIO VALLEY WITH A DRY, STABLE NORTHWEST FLOW THIS WEEKEND.
LIKEWISE TEMPERATURES WILL BE PLEASANT, WITH LOWS AND HIGHS NO
MORE THAN 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
EXTENDED PERIOD STARTS WITH GFS AND ECMWF IN FAIRLY GOOD AGREEMENT
WITH DEVELOPING CLOSED UPPER LEVEL LOW IN SOUTH CENTRAL CANADA AND A
WELL DEFINED RIDGE EXTENDING OVER THE GREAT LAKES.
AN UPPER LEVEL SHORTWAVE AHEAD OF THE CLOSED LOW WILL BRING THE
CHANCE FOR PRECIPITATION MONDAY AND TUESDAY. MODEL SOLUTIONS THEN
DIVERGE ON TIMING AND INTENSITY OF THE UPPER LOW AS IT DIVES
SOUTHWARD OVER THE GREAT LAKES FOR THE LATTER HALF OF THE WEEK.
THUS...KEPT A PERSISTENCE FORECAST OF CHANCE POPS THROUGH
MIDWEEK. EXPECT TEMPERATURES TO BE SLIGHTLY ABOVE NORMAL FOR THE
FIRST HALF OF THE WEEK MODERATING TO NEAR NORMAL AS UPPER LOW
CROSSES THE GREAT LAKES BY THE END OF THE WEAK.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL ALLOW FOR MOSTLY VFR CONDITIONS TO PREVAIL ACROSS
THE TERMINALS. THERE IS A SLIGHT CHANCE THAT AN ISOLATED SHOWER OR
THUNDERSTORM COULD DEVELOP OVERNIGHT, ALTHOUGH CHANCES ARE TOO LOW
TO MENTION IN THE TAFS. WITH WINDS BECOMING NEAR CALM OVERNIGHT,
THE LAMP SUPPORTS THE POTENTIAL FOR RADIATION FOG TO DEVELOP NEAR
DAWN AT KZZV/KFKL/KDUJ.
VFR CONDITIONS WILL PREVAIL EARLY ACROSS THE TERMINALS ON FRIDAY.
SHOWERS AND THUNDERSTORMS WITH RESTRICTIONS WILL BE LIKELY TOMORROW
AFTERNOON AND EVENING AS A COLD FRONT DROPS SOUTHWARD ACROSS THE
AREA.
.OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
THE CHANCE OF THUNDERSTORMS WILL CONTINUE FRIDAY NIGHT AS THE COLD
FRONT IS SLOW TO DROP SOUTHWARD. VFR CONDITIONS WILL PREVAIL FOR THE
WEEKEND AS HIGH PRESSURE PASSES TO THE NORTHEAST. THE NEXT COLD
FRONT WILL RETURN THE CHANCE OF SHOWERS AND THUNDERSTORMS MONDAY
INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
645 PM CDT THU MAY 3 2012
.UPDATED FOR AVIATION DISCUSSION BELOW...
.DISCUSSION...
TSTMS BEGINNING TO REDEVELOP IN S MN IN VICINITY OF OLD OUTFLOW
BOUNDARY FROM MORNING CONVECTION. AIRMASS HAS HAD SOME TIME TO
RECOVER WITH SUNSHINE...WITH MSAS SHOWING AXIS OF SBLIS FROM B5 TO
B8 FROM FRM TOWARD RKX. LOW LEVEL SHEAR VALUES NOT REAL
IMPRESSIVE...SO EXPECT MAINLY HAILERS AND SOME POTENTIAL OF HEAVY
RAIN WITH CELLS PROPAGATING/REFORMING ALONG BOUNDARY.
BOUNDARY SAGS SOUTH LATER TONIGHT INTO FRIDAY AS CANADIAN HIGH
PRESSURE BUILDS SLIGHTLY SOUTH. THIS SHOULD FOCUS MOST OF THE
SEVERE THREAT S OF OUR AREA...BUT BOUNDARY DOES TRY AND PUSH NORTH
IN THE AFTN TOWARD SW MN. HOWEVER...DIRTY SW FLOW CONTINUES TO
BRING SHORTWAVES THRU AND MID LEVEL FLOW BACKS (700 MB WINDS) TO
PRODUCE FAVORABLE UPGLIDE TO KEEP SHOWERS AND SOME TSTMS IN
FORECAST. EXPECT MORE CLOUDS TOMORROW WHICH WILL HOLD BACK TEMPS A
FEW DEGREES FROM TODAY.
KEPT POPS IN CHANCE RANGE THEN THRU SATURDAY THEN GOING LIKELY LATE
SATURDAY INTO SUNDAY AS COLD FRONT AND UPPER TROF MOVES THRU AREA.
SHOULD BE A BREAK IN THE SHOWERS FOR MONDAY...BUT SCT MAINLY AFTN AND
EVE SHOWERS AND PERHAPS A FEW TSTMS TO RETURN FOR TUESDAY AS COLD
UPPER LOW DROPS INTO N MN. 500 MB TEMPS OF B24 SHUD BE SUFFICIENT
FOR THE ISOLD TSTM MENTION.
COOLER THEN THRU AT LEAST MID WEEK IN DRIER NW FLOW.
&&
.AVIATION.../00Z TAF ISSUANCE/
EVENING CONVECTION LIMITED TO KEAU THROUGH 02Z. THEN MAINLY HIGH
CLOUDS AROUND MUCH OF THE NIGHT. CONTINUED THE TREND OF BRINGING A
-SHRA INTO KAXN BY 14Z WITH LOWERING CEILINGS TO MVFR AFTER 08-09Z.
THE REMAINDER OF THE REGION SHOULD REMAIN DRY THROUGH 12Z FRI.
MENTIONED SOME LATE AFTERNOON VCSH AT KAXN AS WELL. THE NAM IS
SUGGESTING LOWER STRATUS DEVELOPMENT WITH MOIST NORTHEAST FLOW OFF
LAKE SUPERIOR. PREVIOUS FORECAST HAD MVFR CEILINGS OVER MUCH OF THE
REGION. LIMITED THAT TO NORTHERN AND EASTERN AREAS FOR NOW AND LEFT
IT OUT OF KMSP/KRWF. THIS SHOULD LIFT DURING THE DAY WITH BKN VFR
CEILINGS ANTICIPATED MUCH OF THE DAY FRIDAY. ANY REAL CONVECTIVE
POTENTIAL SHOULD REMAIN SOUTH AND NORTH OF THE AREA INTO FRIDAY
EVENING. NORTHERLY FLOW WILL BECOME MORE EAST LATE TONIGHT AND
INCREASE FRIDAY MORNING...GUSTING TO 25 KNOTS OR SO.
KMSP...AND CONVECTIVE POTENTIAL WILL REMAIN SOUTH OF THE AREA THROUGH
THE NIGHT AS FRONTAL BOUNDARY SAGS SOUTH. MODEL WERE SUGGESTING
SOME POTENTIAL OF STRATUS DEVELOPMENT IN MOIST NORTHEAST LOWER LEVEL
FLOW OFF LAKE SUPERIOR. THE LATEST RUC AND HRRR SUGGEST THIS WILL NOT
OCCUR THIS FAR SOUTH AND WEST...AND MENTIONED SCT020 LATE TONIGHT
FOR NOW. SHOULD LIFT TO BKN VFR CEILING DURING THE LATE MORNING
WITH INCREASING EASTERLY FLOW...GUSTING AROUND 20 KNOTS POSSIBLE.
NEXT CHANCE OF CONVECTION SHOULD REMAIN OUT OF THE PICTURE UNTIL
LATER FRIDAY NIGHT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BAP/DE
AREA FORECAST DISCUSSION
NWS GLASGOW MT
839 PM MDT THU MAY 3 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...
ONLY CHANGE TO FORECAST FOR THIS UPDATE HAS BEEN TO REMOVE THUNDER
FROM THIS EVENINGS SHOWERS. TOPS IN MOST INTENSE AREAS OF
PRECIPITATION THIS EVENING HAVE BEEN BELOW 20KFT WITH VERY LIMITED
INSTABILITY IN THE EVENING SOUNDING. A BOLT OF LIGHTNING IS NOT
IMPOSSIBLE OVERNIGHT...BUT CHANCES ARE NOT HIGH ENOUGH TO MERIT MENTION.
REST OF SHORT TERM FORECAST LOOKS TO BE ON TRACK WITH A BAND OF
LIGHT SHOWER ACTIVITY INDICATED BY THE LATEST NAM AND HRRR MODELS
AGREEING WELL WITH THE CURRENT RADAR PRESENTATION. SOME LIGHT
SHOWER ACTIVITY IS TO BE EXPECTED OVERNIGHT OVER MOST OF THE AREA. MARTIN
PREVIOUS FORECAST...
UNSETTLED PATTERN CONTINUES FOR THE AREA AS SOUTHWEST FLOW BRINGS
A DISTURBANCE AND DECENT SHOWER COVERAGE TONIGHT AND AGAIN
SATURDAY...BUT MAINLY WITH AN UPPER TROUGH.
INCREASING CLOUDS WILL THICKEN FROM THE SOUTHWEST THIS EVENING AS
SHOWER ACTIVITY RAPIDLY BREAKS OUT FROM SOUTHWEST TO NORTHEAST. QPF
LOOKS TO BE HEAVIEST ACROSS THE NORTHEAST BY THE TIME THIS
DISTURBANCE EXITS FRIDAY MORNING. QPF OF OVER A QUARTER OF AN
INCH LOOK LIKELY.
WE THEN RECEIVE A BREAK FRIDAY AND THE PRESSURE GRADIENT RELAXES A
BIT DUE TO LIGHTER WINDS. THE NEXT DISTURBANCE THEN MOVES IN FOR
SATURDAY AND POSSIBLY A SLOWER MOVING ONE AS SOME OF THE MODELS
ARE SHOWING THE UPPER LEVEL FLOW TO CUT-OFF A BIT. THIS SYSTEM
WILL BRING ANOTHER DECENT BATCH OF RAIN.
TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH THE PERIOD. JAMBA
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
NOT TOO MANY CHANGES TO THE LONG TERM FORECAST JUST DROPPED THE
POPS MONDAY NIGHT THROUGH THURSDAY MORNING. UPPER RIDGE BUILDS IN
BEHIND THE COMPACT CYCLONE THAT IMPACTS THE REGION OVER THE
WEEKEND. EXPECT THIS UPPER RIDGING TO MOVE OVER EASTERN MONTANA
MONDAY NIGHT INTO TUESDAY. THIS SHOULD PROVIDE CLEARING SKIES AND
WARMING OF TEMPERATURES INTO THE LATER PART OF THE WEEK. MODELS
ARE OUT OF PHASE PAST THURSDAY SO DID NOT MAKE ANY CHANGES BEYOND
THIS POINT. 12Z ECMWF HAS A FAST MOVING SHORTWAVE MOVING ACROSS
EASTERN MONTANA DURING THE WEDNESDAY NIGHT THURSDAY MORNING TIME
FRAME WHILE THE 12Z GFS IS SLOWER WITH THIS FEATURE...THURSDAY
EVENING TIME FRAME. RSMITH
PREVIOUS DISCUSSION...A DEVELOPING COMPACT CYCLONE WILL BE IN
POSITION OVER NORTHEAST MONTANA SATURDAY EVENING IN THE PROCESS OF
LIFTING INTO CANADA. THIS WILL SHIFT GUSTY WINDS AROUND TO THE
NORTHWEST AS THE LOW CENTER DRAGS IN A DRY SLOT FROM THE SOUTH.
THIS ACTION MAY CUT OFF THE ON-GOING RAIN SHOWERS IN THE SOUTHERN
ZONES...WHILE RAIN CONTINUES OVER THE NORTHERN ZONES. BOTH GFS AND
THE EC INDICATE THIS DRY SLOT...SO WILL DO SOME CARVING OR
LIMITING OF POPS THERE. THIS STORMS BRINGS CONSIDERABLE
INSTABILITY INTO THE DAKOTAS IN THE FORM OF STRONG CAPE AND STEEP
LAPSE RATES...THE CLOSE PROXIMITY OF WHICH WOULD SUGGEST
THUNDERSTORMS FOR NEMONT ON SATURDAY EVENING. IT IS LIKELY THE
PROBABLE SEVERE STORMS WILL BE TO OUR SOUTHEAST...BUT SOME SMALL
HAIL PRODUCING STORMS MAY BE POSSIBLE FOR OUR SOUTHEASTERN ZONES.
THE STACKED LOW CENTER MOVES INTO SOUTHERN MANITOBA AND
SASKATCHEWAN ON SUNDAY...WHICH SHOULD GENERATE STRONG
NORTHWESTERLY WINDS OVER OUR AREA. AS THE LOW CENTER BEGINS TO
DESCEND INTO NORTH DAKOTA ADDITIONAL MOISTURE BANDS WRAPPING
AROUND THE BACK SIDE OF THE LOW WILL CONTINUE PERIODS OF RAIN
SHOWERS OVER EASTERN MONTANA INTO MONDAY AND TUESDAY. WITH
THICKNESS HEIGHTS FALLING TO LESS THAN 545DM...TEMPERATURES WILL
COOL TO BELOW NORMAL ON MONDAY AND TUESDAY. HOWEVER LOWS WILL BE
ONLY SEVERAL DEGREES BELOW NORMAL.
THE STORM HEADS FARTHER EAST BY WEDNESDAY ALLOWING A NARROW UPPER
LEVEL RIDGE TO MOVE INTO MONTANA. TEMPERATURES SHOULD REBOUND TO
NORMAL FOR THE REMAINDER OF THE EXTENDED PERIOD. MODELS DO HINT
THAT THE RIDGE MIGHT BE PUSHED ASIDE BY A LONG WAVE TROUGH DIGGING
INTO WESTERN CANADA. THE MAIN AFFECT HERE COULD BE COOLING AGAIN
FOR THE FOLLOWING WEEKEND. SCT
&&
.AVIATION...
RAIN SHOWERS INCREASING IN AREA TO BECOME NUMEROUS TONIGHT.
OVERCAST CEILINGS WILL BE LOWERING TO BETWEEN 3000 FT AGL TO 2000
FT AGL AT THE KGGW AND KOLF TERMINALS LATE THIS EVENING. THESE
CONDITIONS WILL SPREAD EAST ACROSS THE KGDV AND KSDY TERMINALS
AFTER MIDNIGHT. RSMITH/SIMONSEN
&&
.HYDROLOGY...
A COUPLE OF RAINY SYSTEMS WILL AFFECT THE AREA OVER THE NEXT COUPLE
OF DAYS. THE NEXT ONE COMES TONIGHT WITH THE SECOND ONE COMING
SATURDAY. WITH SOME RIVER GAUGES RUNNING SLIGHTLY ABOVE NORMAL (IN
THE 76TH TO 90TH PERCENTILE)...THERE COULD BE MINOR FLOODING IN THE
AREA BY SUNDAY. WILL HIGHLIGHT THIS IN AN HWO. JAMBA
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
637 PM CDT THU MAY 3 2012
.UPDATE...
.AVIATION...
VFR IS GENERALLY EXPECTED MOST AREAS TONIGHT AND FRIDAY.
BOTH THE RUC AND HRRR MODELS ARE DRAWING THE WARM MOIST AIR ACROSS
CNTL AND ERN NEBRASKA WEST THROUGH KLBF FROM ABOUT 06Z ONWARD.
THIS SUGGESTS STRATUS OR FOG WILL DEVELOP FRIDAY MORNING EAST OF
KOGA AND SOUTH OF KTIF THROUGH KBBW AND KLBF. BURNOFF SHOULD BE
AROUND 15Z WITH VFR ALL AREAS THEREAFTER. THEREFORE EXPECT AREAS
OF MVFR TO DEVELOP TOWARD MORNING BUT CONDITIONS MAY SUPPORT
IFR/LIFR CIGS AND VSBY IF THE RUC AND HRRR WERE TO VERIFY
EXPLICITLY.
ISOLATED TSTMS MAY DEVELOP THIS EVENING IN THE WARM MOISTURE BEING
DRAWN WEST AND ISOLATED OR SCATTERED STRONG OR SEVERE THUNDERSTORMS
ARE POSSIBLE LATE FRIDAY AFTN...GENERALLY ALONG AND EAST OF HIGHWAY 83.
&&
.PREV DISCUSSION... /ISSUED 310 PM CDT THU MAY 3 2012/
SYNOPSIS...
H5 ANALYSIS THIS MORNING INDICATING BROAD WEST SOUTHWESTERLY FLOW
ACROSS THE WESTERN CONUS...WITH NUMEROUS EMBEDDED SHORTWAVES NOTED
ACROSS THE INTERMOUNTAIN WEST. WV IMAGERY THIS MORNING IS INDICATING
A WAVE OVER NRN UT...WRN NV...AS WELL AS SRN UT. RIDGING EXTENDED
ACROSS THE SERN US NWD INTO THE MID ATLANTIC...WHILE A TROUGH OF LOW
PRESSURE EXTENDED FROM THE AK PANHANDLE SWD TO THE NRN CA COAST.
AT THE SURFACE...A WEAK FRONTAL BOUNDARY EXTENDED FROM NEAR KEARNEY
TO NORFOLK...TO FAR SERN SD. SRLY WINDS WERE PRESENT SOUTH OF THIS
FEATURE...WITH DEW POINTS IN THE 60S. WEST OF THIS FEATURE...WEAK
NORTHEASTERLY FLOW WAS PRESENT WITH DEW POINTS IN THE 40S TO LOWER
50S. TEMPERATURES AS OF 2 PM CDT RANGED FROM 72 AT AINSWORTH...TO 79
AT NORTH PLATTE.
DISCUSSION...
NEAR TERM...TONIGHT THROUGH SUNDAY NIGHT...MAIN FORECASTING
CHALLENGES OVER THE NEXT COUPLE OF DAYS DEAL WITH THUNDERSTORM
CHANCES AND SEVERE POTENTIAL FOR FRIDAY NIGHT AND SATURDAY NIGHT.
TEMPERATURES SUNDAY WILL BE THE FORECAST CHALLENGE FOR THE LATTER
HALF OF THE WEEKEND.
FOR TONIGHT...CONVECTION IS EXPECTED TO FIRE IN A COUPLE OF
LOCATIONS THIS EVENING. THE FIRST JUST OFF TO THE EAST OF THE
FORECAST AREA IN THE VICINITY OF THE BEFORE MENTIONED FRONTAL
BOUNDARY AND THE SECOND ACROSS THE PANHANDLE AND NORTHWESTERN CWA
LATER TONIGHT. FOR WESTERN AREAS...ELEVATED INSTABILITY WILL
INCREASE OVERNIGHT AS STRONG MID LEVEL WARM AIR ADVECTION LIFTS FROM
EASTERN WYOMING INTO THE NORTHERN NEBRASKA PANHANDLE AND WESTERN
SOUTH DAKOTA. CONVECTION IS EXPECTED TO CONTINUE INTO THE OVERNIGHT
HOURS THANKS TO THE DEVELOPMENT OF A LOW LEVEL JET ACROSS THE
PANHANDLE. GIVEN THE LACK OF BOUNDARY LAYER MOISTURE ACROSS THE
EASTERN PANHANDLE AND NORTH WESTERN NEBRASKA TONIGHT...AND LIMITED
DEEP LAYER SHEAR...NOT EXPECTING ANY SEVERE STORMS WITH THIS
ACTIVITY. MID LEVEL STEERING WINDS WILL CARRY THIS ACTIVITY ENE INTO
PORTIONS OF NORTH CENTRAL NEBRASKA OVERNIGHT...SO POPS IN THESE
AREAS WILL CONTINUE. THE GFS DEVELOPS CONVECTION ACROSS THE CENTRAL
NEBRASKA PANHANDLE AND LIFTS IT SEWD INTO SWRN NEBRASKA OVERNIGHT.
GIVEN THE DIRECTION OF MID LEVEL FLOW AND A WEAKLY SHEARED
ENVIRONMENT...RIGHT MOVING STORMS DID NOT SEEM PLAUSIBLE ATTM AND
KEPT SWRN NEBRASKA DRY. OVERNIGHT LOWS WILL BE MILD WITH READINGS IN
THE UPPER 40S AND LOWER 50S.
FOR FRIDAY AND FRIDAY NIGHT...LOW LEVEL MOISTURE WILL SURGE NORTH ON
FRIDAY AS THE FRONTAL BOUNDARY WASHES OUT AND LIFTS NORTH AS A WEAK
WARM FRONT. BY FRIDAY AFTERNOON...55+ DEW POINTS WILL EXTEND AS FAR
WEST AS A LINE FROM OGALLALA TO WEST OF VALENTINE THIS LINE WILL
SURGE EAST ACROSS THE SANDHILLS FRIDAY AFTERNOON...WITH A BULGING
DRY LINE NOTED ALONG HIGHWAY 2 FROM THEDFORD TO MULLEN. THE CAP WILL
ERODE TO ALMOST NOTHING MID AFTERNOON. AND THIS COUPLED WITH THE
BULGING DRY LINE WILL INITIATE STORMS ACROSS THE SANDHILLS. THIS
ACTIVITY WILL INTENSIFY QUICKLY BASED ON EXPECTED BULK SHEAR. THIS
ACTIVITY WILL LIFT TO THE EAST NORTHEAST FRIDAY EVENING...IMPACTING
NORTH CENTRAL NEBRASKA. FURTHER SOUTH...BASED ON THE WIND TRAJECTORY
AND THE AND LACK OF CONVECTIVE DEVELOPMENT OVER NERN COLORADO...POPS
WILL BE LIMITED IN THE SOUTHWESTERN ZONES AND WILL KEEP HIGHEST
POPS ACROSS THE NORTH AND NORTHEAST.
SATURDAY AND SATURDAY NIGHT...SOME MAJOR MODEL DIFFERENCES WERE
NOTED THIS MORNING AS TO WHERE SURFACE LOW PRESSURE RESIDES ON
SATURDAY. THE GFS AND EURO SOLN HAVE THIS FEATURE ALONG THE KS/CO
BORDER WHILE THE NAM HAS IT AROUND 100 MILES EAST OF GOODLAND KS.
THESE DIFFERENCES WILL PLAY A LARGE ROLE IN WHERE THE DRY LINE SETS
UP...AND WHERE CONVECTION DECIDES TO FIRE SATURDAY AFTERNOON/EVE.
THE LATEST GFS SOLN FIRES THIS ACROSS CENTRAL AND NORTHERN NEBRASKA
SATURDAY AFTERNOON IN THE VICINITY OF THE A WARM FRONT AND ALONG AN
INVERTED TROUGH AXIS LOCATED IN THE EASTERN PANHANDLE. GENERALLY WENT
WITH THE HIGHEST POPS IN THE NORTHERN ZONES BASED ON THE LOCATION OF
THE WARM FRONTAL BOUNDARY...AND BEST MID LEVEL FORCING. ATTM.
LOCATIONS SOUTH OF THE WARM FRONT....WILL BE FAIRLY CAPPED AND
PRECIPITATION WILL HAVE TO WAIT UNTIL A SECONDARY COLD FRONT ARRIVES
SATURDAY NIGHT. THIS SECONDARY COLD FRONT WILL SPREAD PRECIPITATION
TO THE BULK OF THE CWA LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING.
WILL RETAIN THE HIGHEST POPS IN THE NORTH AS TWO PERIODS OF
PRECIPITATION ARE POSSIBLE...THE FIRST THREAT EARLY AND THE SECOND
THREAT WITH THE FRONT OVERNIGHT.
ON SUNDAY...THE FRONT WILL CLEAR THE FORECAST AREA BY MID
MORNING...WITH MUCH DRIER AIR PUSHING EAST OF THE AREA SUNDAY NIGHT.
PRECIPITATION CHANCES WILL DIMINISH QUICKLY BEHIND THE FRONT SUNDAY
WITH COOLER HIGHS IN THE 60S EXPECTED.
LONG TERM...MONDAY THROUGH THURSDAY...
SUNDAY THROUGH THURSDAY...STRONG SHORTWAVE MOVING ACROSS SOUTHERN
CANADA...WILL DRIVE A COLD FRONT THROUGH THE AREA SATURDAY NIGHT.
EXPECT A ROUND OF TSTMS WITH THE FRONTAL PASSAGE...AND THEN BREEZY
COOLER WEATHER FOR SUNDAY BEHIND THE FRONT. SFC HIGH PRESSURE WILL
BUILD INTO THE AREA FOR THE FIRST OF THE WEEK...WITH SLIGHTLY BELOW
NORMAL TEMPERATURES. BY THE MIDDLE OF THE WEEK...ENSEMBLES MEMBERS
INDICATE THAT UPPER LEVEL RIDGING WILL DEVELOP ACROSS THE
AREA...WITH WARMING TEMPERATURES. THEN BY THE END OF THE
WEEK...MODELS/ENSEMBLE MEMBERS DIFFER ON THE HANDLING OF A CUT OFF
LOW THAT ATTEMPTS TO PUSH EAST INTO EITHER THE CENTRAL OR SOUTHERN
PLAINS. LATEST ECMWF BUILDS A STRONG UPPER LEVEL RIDGE INTO THE GULF
COAST REGION...WHICH STEERS THE UPPER LOW AND CHANCES FOR RAIN IN
OUR DIRECTION. THIS IS STILL SEVERAL DAYS AWAY...AND FOR NOW WILL
KEEP A DRY FORECAST. HOWEVER...WILL CONTINUE TO MONITOR THE TRENDS
THE NEXT COUPLE OF DAYS FOR POSSIBLE INTRODUCTION OF PRECIP CHANCES
TOWARD THE END OF THE WEEK.
AVIATION...
EXPECTING A WARM FRONT TO LIFT NORTHWARD ACROSS WESTERN AND NORTH
CENTRAL NEB TONIGHT. AS THIS OCCURS...A RAPID INCREASE IN DEW
POINTS/MOISTURE WILL TAKE PLACE. WHILE NOT EXPECTED TO BE WIDESPREAD
AT THIS TIME...WILL HINT AT THE POSSIBILITY OF SOME STRATUS IN THE
TAF AS DEEP MOISTURE SPREADS INTO THE AREA. OTHERWISE...CANNOT
COMPLETELY RULE OUT THE POSSIBILITY OF A TSTM AS THE FRONT LIFTS
NORTH TONIGHT. SFC WINDS SHOULD GRADUALLY SHIFT FROM ENE TO SE
OVERNIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
345 PM CDT WED MAY 2 2012
.SHORT TERM...THROUGH 00Z FRIDAY. MORNING UPPER AIR ANALYSIS INDICATES
QUASI-ZONAL MID AND UPPER LEVEL FLOW ACROSS MUCH OF THE CENTRAL
CONUS...WITH A MID LEVEL SHORTWAVE TROUGH NOTED OVER THE
NORTHWESTERN CONUS. MID AND UPPER LEVEL JET ENERGY REMAINS
RELEGATED TO THE WEST/NORTHWESTERN CONUS...WITH TROPOSPHERIC FLOW
REMAINING FAIRLY LIGHT OVER OUR AREA. WATER VAPOR IMAGERY
INDICATES A PLUME OF MID LEVEL MOISTURE ADVANCING FROM THE PACIFIC
INTO THE SOUTHWESTERN CONUS...ONWARD INTO THE MIDDLE ROCKY
MOUNTAIN RANGE AS WELL AS PORTIONS OF THE CENTRAL AND NORTHERN
PLAINS. EARLY AFTERNOON SURFACE ANALYSIS SHOWS AN AREA OF LOW
PRESSURE OVER SOUTHWESTERN KANSAS...WITH A WARM FRONT EXTENDING
NORTHEASTWARD FROM THE LOW INTO PORTIONS OF NORTH CENTRAL KANSAS
AS WELL AS PORTIONS OF SOUTH CENTRAL AND SOUTHEAST NEBRASKA. AS OF
18Z THIS WARM FRONT WAS NOTED EXTENDING FROM NEAR KHYS...TO NEAR
KK82...TO NEAR KJYR AND KOLU. EARLY AFTERNOON TEMPERATURES ARE
GENERALLY IN THE UPPER 70S AND LOWER 80S ACROSS THE CWA...WITH DEW
POINTS RANGING FROM THE MID 40S AT KLXN...TO THE UPPER 50S THROUGH
THE TRI-CITIES...TO THE MID AND UPPER 60S ACROSS OUR SOUTHEAST
WHERE THE SURFACE WARM FRONT HAS ALREADY CLEARED. EARLY AFTERNOON
VISIBLE SATELLITE IMAGERY SHOWS MOSTLY CLEAR SKIES ACROSS OUR
NORTHWESTERN CWA...WITH THE INCREASED LOW LEVEL MOISTURE VALUES
HELPING PROMOTE INCREASED INSTABILITY AND A RESULTANT EXPANSIVE CU
FIELD.
FOR THE REST OF THIS AFTERNOON AND EARLY THIS EVENING...CONFIDENCE
IS LOW REGARDING CONVECTIVE DEVELOPMENT ACROSS OUR AREA AS FORECAST
PROXIMITY SOUNDINGS FROM THE NAM AND OPERATIONAL GFS SUGGEST
CONVECTIVE INHIBITION SHOULD HOLD FOR THE MOST PART. THAT BEING
SAID...FORECAST PROXIMITY SOUNDINGS FROM THE NAM DO SUGGEST CIN WILL
DECREASE TO ALMOST NOTHING ACROSS OUR EXTREME SOUTHEAST BY 00Z THIS
EVENING...AND WITH THE LOW LEVEL BAROCLINIC ZONE MEANDERING ACROSS
THE AREA THUS PROMOTING LOW LEVEL CONVERGENCE AND RESULTANT
FORCING...FELT IT PRUDENT TO GO WITH A SLIGHT CHANCE POP ACROSS THE
ENTIRE CWA LATE THIS AFTERNOON THROUGH THIS EVENING. THE NAM AND
OPERATIONAL GFS SUGGEST 0-1KM MLCAPE VALUES OF 2000-3500J/KG WILL BE
OBSERVED ACROSS OUR CWA LATE THIS AFTERNOON AND EVENING...WITH THE
GREATEST INSTABILITY LOCATED ACROSS OUR SOUTHEAST WITHIN THE LOW
LEVEL MOISTURE PLUME. WITH MID AND UPPER LEVEL JET ENERGY REMAINING
RELEGATED TO THE WEST/NORTHWEST OF OUR AREA...DEEP LAYER BULK SHEAR IS
NOT OVERLY IMPRESSIVE...BUT GUIDANCE DOES SUGGEST DEEP LAYER BULK
SHEAR VALUES NEAR 30KTS WILL STILL BE POSSIBLE THUS PRESENTING THE
POSSIBILITY FOR ROTATING UPDRAFTS. ALL THAT BEING SAID...SHOULD
CONVECTIVE INITIATION BE REALIZED LATE THIS AFTERNOON OR EARLY THIS
EVENING...SEVERE WEATHER WILL MOST LIKELY BE OBSERVED WITH LARGE
HAIL BEING THE PRIMARY THREAT...AND ISOLATED THUNDERSTORM WIND GUSTS
ALSO POSSIBLE ALONG OUTFLOW. FINALLY...0-1KM SRH IS NOT OVERLY
IMPRESSIVE...WITH THE NAM AND OPERATIONAL GFS SUGGESTING VALUES
SOMEWHERE AROUND 100 M^2/S^2 ACROSS OUR AREA AT 00Z...BUT WITH
LOCALLY ENHANCED LOW LEVEL HORIZONTAL VORTICITY EXISTING IN THE
VICINITY OF LOW LEVEL BAROCLINIC ZONE...ISOLATED TORNADOES ALSO
CANNOT BE RULED OUT.
ATTENTION THEN TURNS TO THE SEVERE POTENTIAL OVERNIGHT TONIGHT. THE
NAM...OPERATIONAL GFS...EC...SREF-MEAN AND HRRR ALL SUGGEST
AFTERNOON AND EVENING HIGH PLAINS CONVECTION WILL MORPH INTO A MCS
AND PUSH EAST INTO PORTIONS OF SOUTH CENTRAL NEBRASKA AND NORTH
CENTRAL KANSAS. AS THE MCS PUSHES EAST IT SHOULD BEGIN INTERACTING
WITH A 40-50KT LOW LEVEL JET WHICH SHOULD HELP SUSTAIN THE MCS IF
NOT HELP IT INTENSIFY THROUGH INCREASED LOW LEVEL MOISTURE FLUX.
GIVEN ALL THIS...A WIDESPREAD SEVERE STRAIGHT LINE WIND EVENT
SOMEWHERE ACROSS OUR CWA IS APPEARING MORE AND MORE LIKELY OVERNIGHT
TONIGHT. AS IS USUALLY THE CASE...EXACT DETAILS REGARDING PLACEMENT AND
TRACK OF THIS MCS WILL NOT LIKELY BE KNOWN UNTIL LATER THIS
EVENING...BUT GIVEN THE LATEST DATA WILL GO AHEAD AND HIGHLIGHT MOST
ALL OF THE CWA FOR SEVERE OVERNIGHT TONIGHT...WITH STRAIGHT LINE
WINDS BEING THE PRIMARY SEVERE WEATHER THREAT. ONE ADDITIONAL
NOTE...THE AFOREMENTIONED MID LEVEL MOISTURE PLUME NOTED ON WATER
VAPOR IMAGERY SHOULD PUSH OVERHEAD TONIGHT THUS HELPING TO INCREASE
PRECIPITABLE WATER VALUES. THESE INCREASING MID LEVEL MOISTURE
VALUES...ALONG WITH THE STRONG CONVECTION CURRENTLY FORECAST...WILL
HAVE THE CAPABILITY TO PROMOTE HEAVY RAINFALL AND PERHAPS LOCALIZED
FLASH FLOODING.
PRECIPITATION CHANCES FOR THURSDAY REMAIN UNCERTAIN AT THIS
POINT...ESPECIALLY WITH THE POTENTIAL FOR A SIGNIFICANT MESO-HIGH
SETTING UP OVER THE AREA DUE TO OVERNIGHT RAIN. ASSUMING THE MESO-HIGH
CAN FULLY DISSIPATE BY MID TO LATE AFTERNOON...AND ASSUMING THERE
IS ENOUGH OMEGA WITH ONE OF THE MANY MID LEVEL PERTURBATIONS WHICH
WILL BE PUSHING OVER THE AREA ALONG THE APPROACHING MID LEVEL JET
AXIS...THURSDAY AFTERNOON 0-1KM MLCAPE VALUES ON THE ORDER OF
1000-2500J/KG COULD CERTAINLY PROMOTE A SEVERE HAIL THREAT. AT
THIS TIME IT APPEARS THE BEST POTENTIAL FOR OBSERVING SEVERE
WEATHER ON THURSDAY WILL BE RELEGATED TO OUR EAST WITHIN THE
BETTER LOW LEVEL MOISTURE...AND WILL GO AHEAD AND HIGHLIGHT OUR
EAST FOR SEVERE WEATHER ON THURSDAY AS A RESULT.
.LONG TERM...STARTING WITH THE MID-TERM THURSDAY EVENING THROUGH
SATURDAY PERIOD...THE RISK OF THUNDERSTORMS...OR LACK
THEREOF...CONTINUES TO BE THE ULTIMATE DILEMMA DURING THESE 48
HOURS AND CONFIDENCE IN THE DETAILS CONTINUES TO RUN BELOW
AVERAGE. ALOFT...A BLEND OF SOLUTIONS FROM THE 12Z NAM/GFS AND 00Z
ECMWF CONTINUE TO ADVERTISE A RATHER PERSISTENT PATTERN...AS
MODESTLY STRONG...BROAD WEST-SOUTHWEST FLOW REMAINS IN
PLACE...DOWNSTREAM FROM A LARGER SCALE SHORTWAVE TROUGH THAT
CARVES OUT ACROSS THE PACIFIC NORTHWEST/NORTHERN ROCKIES. THE
PRIMARY 300MB JET AXIS WILL THUS REMAIN OFF TO THE NORTH AND WEST
OF THE REGION. HOWEVER...CONSIDERABLE CONVECTIVE INSTABILITY WILL
REMAIN FIRMLY IN PLACE IN OR NEAR THE CWA...AS A QUASI-STATIONARY
FRONT WAVERS BACK AND FORTH ACROSS THE GENERAL REGION. BEFORE
CONTINUING...WILL AGAIN STATE THAT CONFIDENCE IN THE DETAILS IS
LOW REGARDING POPS/THUNDER/SEVERE CHANCES...WITH A BIT HIGHER
CONFIDENCE IN TEMPS. HOWEVER...WAS NO LONGER WILLING TO LEAVE THE
FRIDAY THROUGH SATURDAY TIME FRAME COMPLETELY VOID OF ANY
THUNDERSTORM MENTION.
STARTING WITH THURSDAY EVENING/NIGHT...DECIDED TO BLANKET A GENERIC
20 PERCENT CHANCE OF STORMS CWA-WIDE...AS JUST CANNOT GUARANTEE A
STORM-FREE NIGHT ANYWHERE. DETERMINISTIC MODELS ARE ALL OVER THE
PLACE ON QPF PLACEMENT...WITH THE ECWMF ROLLING STORMS IN FROM THE
WEST MAINLY IN THE EVENING...WHILE THE NAM/GFS AFFECT AT LEAST
SOUTHWEST PORTIONS OF THE AREA MAINLY AFTER 06Z. LEANING ON THE 12Z
NAM...ONLY A MODEST LOW LEVEL JET IS PRESENT OVERNIGHT...BUT WITH
SUBTLE SHORTWAVES MOVING THROUGH AND HEALTHY ELEVATED MUCAPE IN
EXCESS OF 2500 J/KG HANGING OUT ACROSS MOST OF THE CWA THROUGH THE
NIGHT...JUST FEEL BETTER HAVING A TOKEN 20 PERCENT CHANCE
EVERYWHERE. HOWEVER...IT IS LIKELY THAT MOST OF THE AREA WILL IN
FACT REMAIN STORM FREE...WITH THE MOST LIKELY SCENARIO FOR POSSIBLE
CONVECTION BEING HIGH PLAINS ACTIVITY DRIFTING IN FROM THE WEST. AS
FOR SEVERE CHANCES THURSDAY NIGHT...DEEP LAYER SHEAR IS NOT ALL THAT
STRONG...20-30 KNOTS AT MOST...BUT OBVIOUSLY WITH HIGH CAPE LEVELS
HANGING AROUND CANNOT RULE OUT AT LEAST MARGINALLY SEVERE HAIL AND
WIND. AS FOR LOW TEMPS...NUDGED UP SLIGHTLY FROM PREVIOUS
FORECAST...WITH MOST OF SOUTHEAST 1/2 OF CWA HOLDING UP IN THE
LOW-MID 60S.
FOR FRIDAY...MUCH OF THE SAME...AS FORCING ALOFT REMAINS
SUBTLE...BUT INSTABILITY REMAINS HIGH WITH AFTERNOON MLCAPE VALUES
AGAIN BUILDING TO AROUND 3000 J/KG OR HIGHER PER THE NAM...ALTHOUGH
THIS MODEL MAY BE OVERDOING DEWPOINTS AND RESULTANT CAPE A BIT.
ALTHOUGH ODDS ARE REASONABLY HIGH THAT MOST OF THE AREA WILL REMAIN
STORM FREE...OPTED TO INTRODUCE A SLIGHT 20 POP ACROSS SEVERAL
COUNTIES NORTH OF I-80...AS HINTED AT BY THE 12Z GFS AND TO A LESSER
EXTENT THE 12Z NAM. AGAIN...ANYTHING THAT HAPPENS TO FIRE IN THIS
AREA BEFORE DARK COULD POTENTIALLY BE SEVERE. TEMP WISE...ASSUMING
THAT SOUTHERLY BREEZES ARE PRESENT AND CLOUDS ARE NOT
WIDESPREAD...THIS HAS THE POTENTIAL TO BE A RATHER WARM DAY.
ALTHOUGH STILL NOT AIMING QUITE AS HIGH AS THE NAM SUGGESTS...NUDGED
UP A FEW DEGREES...NOW PUTTING MOST OF THE CWA IN THE 87-90 RANGE.
FRIDAY NIGHT...INTRODUCED MORE SLIGHT THUNDERSTORM CHANCES MAINLY
NORTH OF I-80 IN CLOSEST PROXIMITY TO TRACK OF SUBTLE
SHORTWAVES...AND IN THE PRESENCE OF CONTINUED HEALTHY ELEVATED
INSTABILITY. FOR THE DAYTIME HOURS SATURDAY...JUST CONTINUED WITH
MORE OF THE SAME...KEEPING THE SAME AREAS NORTH OF INTERSTATE 80 IN
A SLIGHT CHANCE OF STORMS...BUT WITH BETTER FOCUS LIKELY TARGETING
AREAS JUST TO THE NORTH. BY THIS TIME...THE PRIMARY MID LEVEL TROUGH
TO THE WEST WILL BE CENTERED ROUGHLY ALONG A MT-UT AXIS...BUT STILL
WELL TO THE WEST. TEMP WISE SATURDAY...KEPT SUMMER-LIKE READINGS
GOING AND EVEN NUDGED UP A FEW DEGREES FROM PREVIOUS PER MODEL
CONSENSUS...WITH MID-UPPER 80S MOST AREAS...AND SOME LOW 90S MOST
FAVORED IN KS ZONES.
FOCUSING NOW ON THE LONGER TERM PERIODS SATURDAY NIGHT THROUGH
NEXT WEDNESDAY: IN SHORT...EACH AND EVERY PERIOD FEATURES AT LEAST
20-30 PERCENT RAIN CHANCES FOR NOW...ALTHOUGH WILL STATE THE OBVIOUS
THAT SOME OF THESE PERIODS WILL LIKELY END UP BEING DRY...WITH
PLENTY OF TWEAKING LIKELY OVER THE NEXT SEVERAL DAYS. LOOKING AT THE
BIG PICTURE AND LEANING TOWARD A BLEND OF THE 12Z ECMWF/GFS...THERE
IS ACTUALLY REASONABLY HIGH AGREEMENT THAT ON SATURDAY NIGHT AND
SUNDAY NIGHT A FAIRLY WELL DEFINED SURFACE COLD FRONT WILL CROSS THE
AREA...DRIVEN SOUTHWARD IN RESPONSE TO THE AFOREMENTIONED MID LEVEL
SHORTWAVE TROUGH RIDING UP ACROSS THE NORTHERN PLAINS INTO SOUTH
CENTRAL CANADA. AS A RESULT OF THIS FRONTAL PASSAGE...THE HIGHEST
POPS IN THE EXTENDED PERIOD...40S-50S PERCENTS ACROSS MAINLY NEB
ZONES FOR NOW...ARE FOCUSED ON SATURDAY NIGHT. ALTHOUGH DEEP LAYER
WIND SHEAR DOES NOT LOOK OVERLY IMPRESSIVE WITH THIS FRONTAL
PASSAGE...THE GFS HAS MUCAPE VALUES OF AT LEAST 2000-3000 J/KG IN
PLACE DURING THIS TIME FRAME...SO CERTAINLY A SLIGHT RISK OF SEVERE
NOT OUT OF THE QUESTION. IN THE WAKE OF THIS BOUNDARY...TEMPS SUNDAY
ARE CURRENTLY FORECAST ABOUT 10 DEGREES COOLER THAN
SATURDAY...RANGING FROM LOW 70S NORTHWEST TO LOW 80S SOUTHEAST.
BEYOND SUNDAY...THE CURRENTLY ADVERTISED POPS WOULD SEEM TO COME
MORE AND MORE UNDER QUESTION...BUT WILL STICK WITH THEM PER NOW
ACCORDING TO THE ALLBLEND CONSENSUS INITIALIZATION. THE BASIC STORY
INVOLVES A GRADUAL CARVING OUT OF A MID LEVEL TROUGH ACROSS THE
NORTH CENTRAL CONUS...RESULTING IN A NOTICEABLY COOLER TEMP REGIME
THAN THE CURRENT PATTERN. NUDGED DOWN HIGHS SLIGHTLY FOR MONDAY WITH
UPPER 60S-LOW 70S...WHILE TUESDAY CONTINUES TO LOOK LIKE THE COOLEST
DAY OF THE PERIOD WITH HIGHS ONLY MID-UPPER 60S ALL AREAS AND MAYBE
A REBOUND TO NEAR 70 WEDNESDAY. EVEN IF RAIN WERE TO MATERIALIZE
DURING THE MONDAY NIGHT-WEDNESDAY TIME FRAME...HAVE DROPPED THUNDER
MENTION IN THE FORECAST IN FAVOR OF PLAIN SHOWERS...AS MUCAPE PROGS
FROM BOTH THE ECMWF/GFS ADVERTISE VERY LIMITED IF ANY CONVECTIVE
INSTABILITY. IN CLOSING...WANT TO REITERATE THAT ALTHOUGH POPS IN
THE SAT NIGHT-SUNDAY TIME FRAME LOOK QUITE WARRANTED...WOULD EXPECT
TO SEE AN EVENTUAL TRIMMING OF SOME OF THE RAIN CHANCES DURING THE
SUNDAY NIGHT-WEDNESDAY TIME FRAME.
&&
.PREV DISCUSSION... /ISSUED 1228 PM CDT WED MAY 2 2012/
AVIATION...18Z KGRI TAF. PREVAILING VFR CONDITIONS EXPECTED
THROUGH THE NEXT 24 HOURS...WITH PERIODIC MVFR CEILINGS POSSIBLE
03Z-07Z AS CONVECTIVE ACTIVITY WITH MODERATE RAIN PUSHES THROUGH
THE AREA. SURFACE WINDS WILL REMAIN FROM THE SOUTHEAST THROUGH
MUCH OF THE TAF PERIOD...BUT MAY TRANSITION TO MORE OF A
NORTHEASTERLY DIRECTION 03Z-11Z AS A SURFACE BOUNDARY MEANDERS
ACROSS THE AREA. MINIMAL VISIBILITY RESTRICTIONS WILL BE POSSIBLE
03Z-07Z IN MODERATE RAIN...BUT VISIBILITY RESTRICTIONS ARE NOT
OTHERWISE EXPECTED.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM/AVIATION...BRYANT
LONG TERM...PFANNKUCH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1231 AM CDT WED MAY 2 2012
.AVIATION...
06Z TAFS FOR KOMA...KLNK...KOFK.
THUNDERSTORMS WILL AFFECT KOMA FOR A FEW HOURS EARLY THIS MORNING
AND AT LEAST BE IN THE KLNK VICINITY. SOME SCT TO BKN LOW CLOUDS
BELOW 1500 FEET ARE POSSIBLE THROUGH ABOUT 14Z THEN EXPECT AN
OVERALL INCREASE IN LOW LEVEL MOISTURE LATER TODAY. THUNDERSTORM
CHANCES WILL INCREASE AGAIN AFTER 00Z AT KOFK AND AFTER ABOUT 03Z
AT KOMA AND KLNK.
MILLER
&&
.PREV DISCUSSION... /ISSUED 341 PM CDT TUE MAY 1 2012/
SHORT TERM...TONIGHT THROUGH FRIDAY
GOING FCST IS IN GOOD SHAPE...ONLY MINOR TWEAKS MADE. MAIN CONCERN
THEN CONTINUES TO BE PINNING DOWN AREAL COVERAGE OF SVR STORM
ACTIVITY THIS EVENING. AS OF NOW IT APPEARS THAT THE UPPER MIDWEST
WILL BE PRIME FOR SVR STORMS IN ASSOCIATED WITH LIFTING WARM FRONT...
WITH ANOTHER AREA OF RISK ASSOCIATED WITH COOL FRONT CURRENTLY
DROPPING THRU THE DAKOTAS. HRRR AND RAP SOLUTIONS HAVE BEEN RATHER
CONSISTENT TODAY SUGGESTING LINE OF CONVECTION MOVING INTO THE NRN
CWA BY EARLY EVENING. ESRH AROUND 360 M2/S2 AND MUCAPES 2000 J/KG OR
SO SHOULD BE ENOUGH TO POP SOME SVR MAINLY OVER NORTHEAST NEB.
AMPLIFYING TROF DIG OVER THE WRN CONUS WILL REPLACE THE NEAR-ZONAL
FLOW WITH LOW AMPLITUDE UPPER RIDGE GRADUALLY BUILDING OVER THE
PLAINS. THIS WILL ACT TO HINDER BNDRY PROGRESSION ANY FARTHER SOUTH
AND KEEP IT INVOF THE CWA. ON WEDNESDAY...MUCAPES INCREASE TO 4500
J/KG BY AFTERNOON BUT DEEP LAYER SHEAR IS MORE FOCUSED NORTH. THUS
NORTHEAST NEB MAY BE UNDER THE GUN AGAIN LATE WEDNESDAY
AFTN/EVENING. THURSDAY THROUGH FRIDAY MODELS PROG SEVERAL IMPULSES
EJECTING OUT OF THE SOUTHWESTERN STATES MAY HELP DESTABILIZE ENOUGH
TO POP OFF ADDITIONAL CONVECTION.
DEE
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
FAIRLY ACTIVE WEATHER PATTERN SHOULD CONTINUE INTO EARLY NEXT WEEK
AS UPPER TROUGH REMAIN TO OUR WEST...EJECTING WAVES OF ENERGY INTO
THE PLAINS.
WARM ADVECTION FRIDAY NIGHT MAY SPARK THUNDERSTORMS OVER THE
NORTHERN CWA...NORTH OF A EAST-WEST WARM FRONT BISECTING OUR AREA.
THOSE SHOULD MOVE ON OFF TO THE NORTHEAST FAIRLY QUICKLY SATURDAY
MORNING...LEAVING OUR CWA IN A VERY UNSTABLE AIRMASS BY SATURDAY
AFTERNOON. CAPPING UNDER WEAK MID LEVEL RIDGE MAY PRECLUDE
DEVELOPMENT MUCH OF THE DAY...MOST LIKELY WAITING FOR LOWERING
HEIGHTS AS RIDGE SLIDES EAST SATURDAY EVENING. THUNDERSTORMS ARE
GOOD BET THEN...ESPECIALLY IN THE NORTH WHERE A COLD FRONT WILL BE
APPROACHING OVERNIGHT.
THAT FRONT WILL DRIFT ACROSS THE AREA SUNDAY...MAINTAINING A FAIRLY
HIGH CHANCE FOR CONTINUING RAIN AND THUNDER. COOLER AIR WILL
FOLLOW...BUT THE CHANCE FOR RAIN OR SHOWERS WILL STILL EXIST AS
MOIST SOUTHWEST FLOW ALOFT RIDES OVER COOL SURFACE LAYER. THIS
PATTERN PERSISTS THROUGH TUESDAY.
TEMPERATURES LOOK WARM SATURDAY WITH SOUTHERLY FLOW AND MORE
HUMIDITY. HAVE HIGHS IN THE 80S THEN. RAIN AND COLD FRONTAL PASSAGE
WILL COOL HIGHS INTO THE 70S SUNDAY...THEN ONLY 60S FOR MONDAY AND
TUESDAY INFLUENCED BY NORTH TO EAST LOW LEVEL WIND COMPONENT.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1047 AM EDT WED MAY 2 2012
.SYNOPSIS...
WARM SOUTHERLY FLOW WILL PERSIST INTO THE WEEKEND. UPPER
DISTURBANCES WILL BRING CHANCES OF SHOWERS AND THUNDERSTORMS
MOSTLY TOWARDS THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SKIES HAVE CLEARED ACROSS MOST OF THE AREA. THERE WAS SOME ACCAS
ACROSS THE SOUTHERN ZONES EARLIER INDICATING MID LEVEL INSTABILITY
IN PLACE. STRONG HEATING WILL TAKE PLACE WHICH WILL RESULT
CONSIDERABLE INSTABILITY. RAP AND HRRR RUNS SUGGEST THAT
SCATTERED STORMS WILL DEVELOP MAINLY ACROSS THE SOUTHERN COUNTIES
AS A WEAK DISTURBANCE MOVES THROUGH THE FLOW. SHEAR WILL BE WEAK
SO STORMS SHOULD BE DISORGANIZED. BUT GIVEN FORECAST INSTABILITY
CANNOT RULE OUT ISOLATED SEVERE STORMS.
ALSO HAVE TO WATCH FAR NORTHERN COUNTIES LATE IN THE DAY. OUTFLOW
BOUNDARY FROM EARLIER CONVECTION TO THE NORTHWEST WILL APPROACH
THE REGION AND SERVE AS A FOCUS FOR MORE STORMS. IT IS MORE A
QUESTION OF WHETHER THEY WILL WORK AS FAR SOUTH AS THE FORECAST
AREA. SHEAR WILL BE SOMEWHAT BETTER IN THAT REGION.
WINDS WILL BECOME GUSTY AS INVERSION BREAKS. FORECAST TEMPERATURES
LOOK REASONABLE AT THIS POINT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
WHILE THE SMALL THREAT FOR SHOWERS AND STORMS SHOULD END FOR MOST
OF THE CWA DURING THE EVENING...A WEAK SHORTWAVE FOLLOWING THE
CREST OF THE RIDGE THROUGH MICHIGAN WILL EVENTUALLY TURN SLIGHTLY
SOUTHEASTWARD...MOVING INTO EASTERN OHIO AND PENNSYLVANIA BY LATE
IN THE EVENING. THE PROBABILITY OF A SIGNIFICANT AMOUNT OF THIS
ACTIVITY MAKING IT INTO THE FORECAST AREA IS SOMEWHAT
LIMITED...GIVEN THAT IT WILL BE FIGHTING THE RIDGING AND A BIT OF
BOUNDARY LAYER STABILIZATION BY THAT POINT IN THE DAY. COMBINED
WITH MARGINAL SHEAR...THE SEVERE THREAT DOES NOT SEEM TO BE
TERRIBLY HIGH HERE...BUT A FEW STRONG STORMS MAY BE POSSIBLE.
RIDGING WILL BE INCREASING IN STRENGTH BY THURSDAY...LEADING TO A
LESS LIKELY SCENARIO FOR POP UP STORM DEVELOPMENT. THUS...A DRY
FORECAST WILL BE MAINTAINED AT THIS TIME...ALTHOUGH THE VERY WARM
AND POTENTIALLY UNSTABLE CONDITIONS KEEP THIS FROM BEING IN THE
HIGHEST LEVELS OF CONFIDENCE. WHAT THURSDAY WILL BRING...ON MORE
STRONG WARM ADVECTION AND ANOTHER DAY OF SUN...IS HIGH
TEMPERATURES THAT WILL COME CLOSE TO RECORD VALUES.
A SHORTWAVE WILL BE MOVING TOWARD THE AREA ON FRIDAY...FINALLY
PROVIDING A BIT OF FOCUS FOR CONVECTION. WITH INCREASED CHANCES OF
STORMS (POSSIBLY STRONG) ON FRIDAY...AND EARLIER TIMING THAN
PREVIOUSLY FORECAST...TEMPERATURES WERE REDUCED SLIGHTLY. THE
HIGHEST TEMPS WILL STILL BE IN THE SOUTHEAST.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
FOR SATURDAY AND SUNDAY...THE PRIMARY THREAT FOR THUNDERSTORMS
WILL SHIFT SOUTH NEAR THE OHIO RIVER AS THE BOUNDARY BECOMES
NEARLY STATIONARY OVER KENTUCKY.
A CHANCE OF THUNDERSTORMS WILL OVERSPREAD THE AREA BY LATE MONDAY AS
A STRONGER DISTURBANCE MOVES ALONG THE NORTHERN PERIPHERY OF THE
UPPER RIDGE. WEAK HIGH PRESSURE AND DRIER WEATHER MAY ENTER THE
PICTURE ON TUESDAY.
HIGHS UP IN THE 80S THURSDAY AND FRIDAY WILL SLIP BACK TOWARD NORMAL
READINGS AROUND 70 BY TUESDAY.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
A WARM FRONT WILL LIFT NORTH INTO THE LOWER GREAT LAKES THROUGH
THIS MORNING. MID LVL RIDGE WILL THEN BUILD NORTHWARD INTO THE
OHIO VALLEY. REGION SHOULD BE WARM SECTORED AND CHANCES FOR
SHOWERS AND STORMS WILL BE MINIMAL AND HAVE THUS LEFT OUT OF THE
TAFS. MODEST PRESSURE GRADIENT AND DAYTIME MIXING WILL ALLOW WINDS
TO INCREASE FROM THE SOUTHWEST WITH SOME GUSTS UP TO 25 KNOTS
DURING THE AFTERNOON.
FOR TONIGHT...AN UPPER LEVEL WEATHER DISTURBANCE IS FORECAST TO
TRACK EASTWARD ACROSS THE LOWER GREAT LAKES. AT THIS TIME...IT
APPEARS THE MAIN CONVECTIVE ACTIVITY WILL REMAIN NORTH OF THE TAF
SITES...BUT SHORT TERM MESOSCALE TRENDS WILL HAVE TO BE MONITOR
SHOULD IT SLIDE FARTHER SOUTH INTO THE AREA. HAVE KEPT THE
FORECAST DRY AT THE TAF SITES TONIGHT ATTM.
OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...HATZOS
LONG TERM...CONIGLIO
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1056 PM CDT THU MAY 3 2012
UPDATED SHORT TERM FCST AND AVIATION SECTION FOR THE 06Z TAFS
.UPDATE...TSTMS DISSIPATED AS THEY REACHED CENTRAL WI LATE THIS EVG.
EVEN THOUGH SOME ELEVATED INSTABILITY REMAINS...SFC BASED
INSTABILITY IS ALMOST GONE AND CONVERGENCE HAS WEAKENED ALONG THE
COLD FRONT...SO HAVE REMOVED THUNDER FOR THE REST OF THE NIGHT.
KIECKBUSCH
&&
.PREV DISCUSSION...ISSUED AT 928 PM CDT THU MAY 3 2012...
UPDATE...PERSISTENT CONVERGENCE ALONG APPROACHING COLD FRONT AND
LINGERING INSTABILITY OVER WEST CENTRAL WI HAS RESULTED IN SCT
STRONG TSTMS THIS EVG. KEEP THINKING THAT THESE WILL WEAKEN AS
THEY REACH CENTRAL WI...ESPECIALLY SINCE SBCAPE IS QUICKLY WANING...
BUT THEY CONTINUE TO PULSE UP. HAVE KEPT AN AREA OF MID-RANGE POPS
AND A MENTION OF TSTMS OVER CENTRAL WI THROUGH 06Z TO ACCOUNT FOR
THE REMNANTS OF THESE STORMS AS THEY IMPACT GRB CWA. WOULD BE
SURPRISED IF WE NEEDED TO ISSUE ANY WARNINGS ON THESE STORMS...
BUT SOME SMALL HAIL AND BRIEF HEAVY RAINFALL IS CERTAINLY POSSIBLE.
DO NOT THINK THAT THESE STORMS WILL SURVIVE THE TREK INTO THE
SOUTHERN FOX VALLEY...SO THE AREAS THAT WERE PLAGUED BY FLOODING
THIS PAST MORNING SHOULD BE SPARED TONIGHT. FOR AREAS OUTSIDE OF
CENTRAL WI...HAVE LOWERED POPS TO SLGT CHC AND REMOVED THUNDER.
KIECKBUSCH
DISCUSSION ISSUED AT 658 PM CDT THU MAY 3 2012...
SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW MULTIPLE AREAS
OF LOW PRESSURE RANGING FROM THE UPPER PENINSULA TO CENTRAL KANSAS
EARLY THIS AFTERNOON. ATTACHED TO ONE OF THE LOWS OVER SOUTHERN
MINNESOTA IS A WARM FRONT WHICH HAS MOVED VERY LITTLE FROM MSP TO
MTW. EARLIER MCV HAS DEPARTED THE REGION WHILE WE AWAIT FOR ANOTHER
SMALLER CLUSTER OF STORMS TO PUSH INTO CENTRAL WISCONSIN. IN
GENERAL...THE WIDESPREAD CONVECTION FROM EARLIER TODAY AS WORKED
OVER THE ATMOSPHERE...WHILE CLOUD COVER HAS PREVENTED FULL
SURFACE-BASED HEATING. BETTER HEATING HAS OCCURRED OVER SOUTHERN
WISCONSIN WHERE TEMPS HAVE WARMED INTO THE UPPER 70S TO LOWER 80S.
WILL HAVE TO REACH INTO THE MID TO UPPER 70S FOR A CHANCE OF
ADDITIONAL STORM DEVELOPMENT THROUGH THE REST OF THE AFTERNOON.
WITH ADDITIONAL SHOWERS AND STORMS PUSHING IN FROM THE WEST AND
AMPLE CLOUD COVER OVERHEAD...THINK CHANCES OF THIS OCCURRING IS
FAIRLY LOW. MEANWHILE...A COLD FRONT IS DROPPING SOUTH ACROSS LAKE
SUPERIOR AND NORTHERN MINNESOTA WHERE TEMPS FALL BACK INTO THE 50S.
THE MAIN FORECAST CONCERNS INCLUDE THUNDER AND SEVERE WEATHER
CHANCES TONIGHT.
TONIGHT...THE PESKY SURFACE WARM FRONT WILL CONTINUED TO BE DRAPED
ACROSS CENTRAL WISCONSIN EARLY IN THE EVENING. MODEL GUIDANCE SHOWS
THE RIGHT REAR QUAD OF A JET STREAK BUILDING BACK INTO SOUTHERN AND
CENTRAL WISCONSIN THROUGH THE EVENING. AS A RESULT...THERE IS
ENOUGH SUPPORT ALOFT TO KEEP A HIGH CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST FROM CENTRAL TO NORTHEAST WISCONSIN.
THE LLJ WILL BE DEVELOPING WELL SOUTH AND EAST OF THE REGION...SO
WILL NOT HAVE THE GOOD MASS CONVERGENCE FOR SEVERE STORMS...BUT
PERHAPS ENOUGH FOR ISOLATED TO SCT COVERAGE. A COLD FRONT WILL DROP
INTO NORTHERN WISCONSIN IN THE EVENING...THEN DRIVE INTO CENTRAL
WISCONSIN OVERNIGHT. THIS FRONT WILL END THE SHOWER AND
THUNDERSTORM THREAT...AS WELL AS BRING A RETURN OF NORTHEAST WINDS
AND LESS HUMID CONDITIONS. QUITE A BIT OF LOW STRATO-CU UPSTREAM
BEHIND THE FRONT...AND THINK WILL HAVE A PROBLEM CLEARING ESPECIALLY
WITH THE AMPLE LOW LEVEL MOISTURE LEFT BEHIND FROM THE EXCESSIVE
RAINFALL. LOWS BACK INTO THE 40S NORTH TO THE UPPER 50S SOUTH.
FRIDAY...SURFACE COLD FRONT WILL MOVE FROM CENTRAL WISCONSIN INTO
NORTHERN ILLINOIS AND NORTHEAST IOWA IN THE AFTERNOON. BEHIND THE
FRONT...CANADIAN HIGH PRESSURE WILL BUILD SOUTH ACROSS THE STATE
THROUGH THE DAY. WILL SEE COOLER AND NOTICEABLY DRIER CONDITIONS
ARRIVE...BROUGHT IN BY BRISK NE WINDS. LOOKING UPSTREAM...PLENTY OF
LOW CLOUDS BEHIND THE FRONT OVER SOUTHERN MANITOBA AND ONTARIO...SO
THINK WILL SEE A MOSTLY CLOUDY MORNING...FOLLOWED BY PARTLY SUNNY
CONDITIONS IN THE AFTERNOON. NEXT SYSTEM LOOKS LIKE IT WILL STAY TO
THE WEST AT THIS POINT. HIGHS IN THE 50S NEAR LAKE MICHIGAN...TO
AROUND 70 OVER CENTRAL WISCONSIN.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
MAIN CONCERN FOR THIS PACKAGE WILL BE THE PERIODIC CHANCES FOR
SHOWERS OR THUNDERSTORMS INTO EARLY NEXT WEEK. SOME MODEL DIFFERENCES
NOTED IN TIMING OF THESE SYSTEMS. FIRST SYSTEM EXPECTED TO PUSH
INTO THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL HAVE A SMALL
CHANCE OF SHOWERS ACROSS THE WEST LATE FRIDAY NIGHT...THEN A
CHANCE ACROSS THE ENTIRE AREA SATURDAY. DRY AIR FROM A CANADIAN
HIGH PRESSURE SHOULD LIMIT THE THUNDER POTENTIAL. DID KEEP ISOLATED
THUNDER ACROSS THE FAR WEST AND SOUTH TO MATCH UP WITH LA CROSSE
AND MILWAUKEE.
FOR SATURDAY NIGHT...THERE MAY BE A LINGERING SHOWER SATURDAY
EVENING...THEN THERE WILL BE A CHANCE OF SHOWERS AGAIN LATE
SATURDAY NIGHT ACROSS THE FAR WEST. STRONGER SYSTEM WORKING ACROSS
THE AREA WILL BRING LIKELY CHANCES FOR SHOWERS AND THUNDERSTORMS
SUNDAY INTO SUNDAY NIGHT. WILL CONTINUE TO KEEP A SMALL CHANCES OF
SHOWERS DUE TO DEPARTING SYSTEM...THEN MONDAY NIGHT SHOULD BE MAINLY
DRY.
AN UPPER TROUGH IS THEN EXPECTED TO SWING ACROSS THE AREA TUESDAY
AFTERNOON AND TUESDAY NIGHT...BRINGING ANOTHER CHANCE FOR SHOWERS
AND ISOLATED THUNDERSTORMS. FOR WEDNESDAY...CYCLONIC FLOW WILL GRADUALLY
PUSH EAST. WILL CONTINUE THE SMALL CHANCE FOR SHOWERS. HIGH PRESSURE
THEN BUILDS INTO THE REGION FOR WEDNESDAY NIGHT AND THURSDAY. TEMPERATURES
WILL RUN AT OR BELOW NORMAL DURING THE PERIOD.
&&
.AVIATION...A COLD FRONT WILL CONTINUE TO SAG SOUTH THROUGH THE
AREA OVERNIGHT...AND MAY GENERATE ISOLD SHOWERS UNTIL IT CLEARS
THE FORECAST AREA. A SHALLOW COOL AIR MASS IN THE WAKE OF THE
FRONT WILL BE FAVORABLE FOR LOW CLOUD DEVELOPMENT...AND IFR CIGS
HAVE ALREADY MOVED INTO FAR NORTHERN WI. IT IS NOT A CERTAINTY
THAT THESE LOW CLOUDS WILL OVERSPREAD THE ENTIRE FCST AREA
TONIGHT... BUT POTENTIAL IS THERE SO WILL NOT BACK OFF ON THE
FCST JUST YET. CONFIDENCE IS HIGHER FOR LOW CLOUDS IN THE FOX
VALLEY/LKSHR AREAS...AS WINDS TURN NE OFF THE BAY/LAKE MICHIGAN
LATER TONIGHT. LOW CLOUDS SHOULD BREAK UP BY MID TO LATE FRIDAY
MORNING...BUT STRATOCUMULUS (MAINLY VFR) WILL LIKELY CONTINUE
DURING THE DAY AND EVENING. NE WINDS MAY GUST OVER 20 KTS AT TIMES
IN THE FOX VALLEY AND LKSHR AREAS ON FRIDAY. SOME SHOWERS MAY WORK
THEIR WAY INTO THE WESTERN TAF SITES TOWARD MIDNIGHT FRIDAY NIGHT.
KIECKBUSCH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
928 PM CDT THU MAY 3 2012
.UPDATE...PERSISTENT CONVERGENCE ALONG APPROACHING COLD FRONT AND
LINGERING INSTABILITY OVER WEST CENTRAL WI HAS RESULTED IN SCT
STRONG TSTMS THIS EVG. KEEP THINKING THAT THESE WILL WEAKEN AS
THEY REACH CENTRAL WI...ESPECIALLY SINCE SBCAPE IS QUICKLY WANING...
BUT THEY CONTINUE TO PULSE UP. HAVE KEPT AN AREA OF MID-RANGE POPS
AND A MENTION OF TSTMS OVER CENTRAL WI THROUGH 06Z TO ACCOUNT FOR
THE REMNANTS OF THESE STORMS AS THEY IMPACT GRB CWA. WOULD BE
SURPRISED IF WE NEEDED TO ISSUE ANY WARNINGS ON THESE STORMS...
BUT SOME SMALL HAIL AND BRIEF HEAVY RAINFALL IS CERTAINLY POSSIBLE.
DO NOT THINK THAT THESE STORMS WILL SURVIVE THE TREK INTO THE
SOUTHERN FOX VALLEY...SO THE AREAS THAT WERE PLAGUED BY FLOODING
THIS PAST MORNING SHOULD BE SPARED TONIGHT. FOR AREAS OUTSIDE OF
CENTRAL WI...HAVE LOWERED POPS TO SLGT CHC AND REMOVED THUNDER.
KIECKBUSCH
&&
.PREV DISCUSSION...ISSUED AT 658 PM CDT THU MAY 3 2012...
SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW MULTIPLE AREAS
OF LOW PRESSURE RANGING FROM THE UPPER PENINSULA TO CENTRAL KANSAS
EARLY THIS AFTERNOON. ATTACHED TO ONE OF THE LOWS OVER SOUTHERN
MINNESOTA IS A WARM FRONT WHICH HAS MOVED VERY LITTLE FROM MSP TO
MTW. EARLIER MCV HAS DEPARTED THE REGION WHILE WE AWAIT FOR ANOTHER
SMALLER CLUSTER OF STORMS TO PUSH INTO CENTRAL WISCONSIN. IN
GENERAL...THE WIDESPREAD CONVECTION FROM EARLIER TODAY AS WORKED
OVER THE ATMOSPHERE...WHILE CLOUD COVER HAS PREVENTED FULL
SURFACE-BASED HEATING. BETTER HEATING HAS OCCURRED OVER SOUTHERN
WISCONSIN WHERE TEMPS HAVE WARMED INTO THE UPPER 70S TO LOWER 80S.
WILL HAVE TO REACH INTO THE MID TO UPPER 70S FOR A CHANCE OF
ADDITIONAL STORM DEVELOPMENT THROUGH THE REST OF THE AFTERNOON.
WITH ADDITIONAL SHOWERS AND STORMS PUSHING IN FROM THE WEST AND
AMPLE CLOUD COVER OVERHEAD...THINK CHANCES OF THIS OCCURRING IS
FAIRLY LOW. MEANWHILE...A COLD FRONT IS DROPPING SOUTH ACROSS LAKE
SUPERIOR AND NORTHERN MINNESOTA WHERE TEMPS FALL BACK INTO THE 50S.
THE MAIN FORECAST CONCERNS INCLUDE THUNDER AND SEVERE WEATHER
CHANCES TONIGHT.
TONIGHT...THE PESKY SURFACE WARM FRONT WILL CONTINUED TO BE DRAPED
ACROSS CENTRAL WISCONSIN EARLY IN THE EVENING. MODEL GUIDANCE SHOWS
THE RIGHT REAR QUAD OF A JET STREAK BUILDING BACK INTO SOUTHERN AND
CENTRAL WISCONSIN THROUGH THE EVENING. AS A RESULT...THERE IS
ENOUGH SUPPORT ALOFT TO KEEP A HIGH CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST FROM CENTRAL TO NORTHEAST WISCONSIN.
THE LLJ WILL BE DEVELOPING WELL SOUTH AND EAST OF THE REGION...SO
WILL NOT HAVE THE GOOD MASS CONVERGENCE FOR SEVERE STORMS...BUT
PERHAPS ENOUGH FOR ISOLATED TO SCT COVERAGE. A COLD FRONT WILL DROP
INTO NORTHERN WISCONSIN IN THE EVENING...THEN DRIVE INTO CENTRAL
WISCONSIN OVERNIGHT. THIS FRONT WILL END THE SHOWER AND
THUNDERSTORM THREAT...AS WELL AS BRING A RETURN OF NORTHEAST WINDS
AND LESS HUMID CONDITIONS. QUITE A BIT OF LOW STRATO-CU UPSTREAM
BEHIND THE FRONT...AND THINK WILL HAVE A PROBLEM CLEARING ESPECIALLY
WITH THE AMPLE LOW LEVEL MOISTURE LEFT BEHIND FROM THE EXCESSIVE
RAINFALL. LOWS BACK INTO THE 40S NORTH TO THE UPPER 50S SOUTH.
FRIDAY...SURFACE COLD FRONT WILL MOVE FROM CENTRAL WISCONSIN INTO
NORTHERN ILLINOIS AND NORTHEAST IOWA IN THE AFTERNOON. BEHIND THE
FRONT...CANADIAN HIGH PRESSURE WILL BUILD SOUTH ACROSS THE STATE
THROUGH THE DAY. WILL SEE COOLER AND NOTICEABLY DRIER CONDITIONS
ARRIVE...BROUGHT IN BY BRISK NE WINDS. LOOKING UPSTREAM...PLENTY OF
LOW CLOUDS BEHIND THE FRONT OVER SOUTHERN MANITOBA AND ONTARIO...SO
THINK WILL SEE A MOSTLY CLOUDY MORNING...FOLLOWED BY PARTLY SUNNY
CONDITIONS IN THE AFTERNOON. NEXT SYSTEM LOOKS LIKE IT WILL STAY TO
THE WEST AT THIS POINT. HIGHS IN THE 50S NEAR LAKE MICHIGAN...TO
AROUND 70 OVER CENTRAL WISCONSIN.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
MAIN CONCERN FOR THIS PACKAGE WILL BE THE PERIODIC CHANCES FOR
SHOWERS OR THUNDERSTORMS INTO EARLY NEXT WEEK. SOME MODEL DIFFERENCES
NOTED IN TIMING OF THESE SYSTEMS. FIRST SYSTEM EXPECTED TO PUSH
INTO THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL HAVE A SMALL
CHANCE OF SHOWERS ACROSS THE WEST LATE FRIDAY NIGHT...THEN A
CHANCE ACROSS THE ENTIRE AREA SATURDAY. DRY AIR FROM A CANADIAN
HIGH PRESSURE SHOULD LIMIT THE THUNDER POTENTIAL. DID KEEP ISOLATED
THUNDER ACROSS THE FAR WEST AND SOUTH TO MATCH UP WITH LA CROSSE
AND MILWAUKEE.
FOR SATURDAY NIGHT...THERE MAY BE A LINGERING SHOWER SATURDAY
EVENING...THEN THERE WILL BE A CHANCE OF SHOWERS AGAIN LATE
SATURDAY NIGHT ACROSS THE FAR WEST. STRONGER SYSTEM WORKING ACROSS
THE AREA WILL BRING LIKELY CHANCES FOR SHOWERS AND THUNDERSTORMS
SUNDAY INTO SUNDAY NIGHT. WILL CONTINUE TO KEEP A SMALL CHANCES OF
SHOWERS DUE TO DEPARTING SYSTEM...THEN MONDAY NIGHT SHOULD BE MAINLY
DRY.
AN UPPER TROUGH IS THEN EXPECTED TO SWING ACROSS THE AREA TUESDAY
AFTERNOON AND TUESDAY NIGHT...BRINGING ANOTHER CHANCE FOR SHOWERS
AND ISOLATED THUNDERSTORMS. FOR WEDNESDAY...CYCLONIC FLOW WILL GRADUALLY
PUSH EAST. WILL CONTINUE THE SMALL CHANCE FOR SHOWERS. HIGH PRESSURE
THEN BUILDS INTO THE REGION FOR WEDNESDAY NIGHT AND THURSDAY. TEMPERATURES
WILL RUN AT OR BELOW NORMAL DURING THE PERIOD.
&&
.AVIATION...SCT TSTMS WERE DEVELOPING ALONG A COLD FRONT OVER WEST
CENTRAL WISCONSIN EARLY THIS EVG. INSTABILITY IS A BIT WEAKER TO
THE EAST OF THE STORMS...AND CURRENT ACTIVITY WOULD NOT ARRIVE IN
CENTRAL WI UNTIL AFTER SUNSET...SO EXPECT THESE STORMS TO WEAKEN
OR DISSIPATE BEFORE REACHING THE AUW/CWA TAF SITES. HAVE KEPT A
VCSH IN THE THOSE TAF SITES FOR THE EARLY EVG. THE COLD FRONT
WILL CONTINUE TO SAG SOUTH THROUGH THE AREA THIS EVG AND EARLY
FRIDAY MORNING. A SHALLOW COOL AIR MASS IN THE WAKE OF THE FRONT
WILL BE FAVORABLE FOR LOW CLOUD DEVELOPMENT...WITH PSBL IFR CIGS.
LOW CLOUDS SHOULD BREAK UP BY MID-LATE MORNING...BUT STRATOCUMULUS
(MAINLY VFR) WILL LIKELY CONTINUE DURING THE DAY. GUSTY NE WINDS
ARE EXPECTED IN THE FOX VALLEY AND LKSHR AREAS LATE TONIGHT AND
FRIDAY.
KIECKBUSCH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
658 PM CDT THU MAY 3 2012
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW MULTIPLE AREAS
OF LOW PRESSURE RANGING FROM THE UPPER PENINSULA TO CENTRAL KANSAS
EARLY THIS AFTERNOON. ATTACHED TO ONE OF THE LOWS OVER SOUTHERN
MINNESOTA IS A WARM FRONT WHICH HAS MOVED VERY LITTLE FROM MSP TO
MTW. EARLIER MCV HAS DEPARTED THE REGION WHILE WE AWAIT FOR ANOTHER
SMALLER CLUSTER OF STORMS TO PUSH INTO CENTRAL WISCONSIN. IN
GENERAL...THE WIDESPREAD CONVECTION FROM EARLIER TODAY AS WORKED
OVER THE ATMOSPHERE...WHILE CLOUD COVER HAS PREVENTED FULL
SURFACE-BASED HEATING. BETTER HEATING HAS OCCURRED OVER SOUTHERN
WISCONSIN WHERE TEMPS HAVE WARMED INTO THE UPPER 70S TO LOWER 80S.
WILL HAVE TO REACH INTO THE MID TO UPPER 70S FOR A CHANCE OF
ADDITIONAL STORM DEVELOPMENT THROUGH THE REST OF THE AFTERNOON.
WITH ADDITIONAL SHOWERS AND STORMS PUSHING IN FROM THE WEST AND
AMPLE CLOUD COVER OVERHEAD...THINK CHANCES OF THIS OCCURRING IS
FAIRLY LOW. MEANWHILE...A COLD FRONT IS DROPPING SOUTH ACROSS LAKE
SUPERIOR AND NORTHERN MINNESOTA WHERE TEMPS FALL BACK INTO THE 50S.
THE MAIN FORECAST CONCERNS INCLUDE THUNDER AND SEVERE WEATHER
CHANCES TONIGHT.
TONIGHT...THE PESKY SURFACE WARM FRONT WILL CONTINUED TO BE DRAPED
ACROSS CENTRAL WISCONSIN EARLY IN THE EVENING. MODEL GUIDANCE SHOWS
THE RIGHT REAR QUAD OF A JET STREAK BUILDING BACK INTO SOUTHERN AND
CENTRAL WISCONSIN THROUGH THE EVENING. AS A RESULT...THERE IS
ENOUGH SUPPORT ALOFT TO KEEP A HIGH CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST FROM CENTRAL TO NORTHEAST WISCONSIN.
THE LLJ WILL BE DEVELOPING WELL SOUTH AND EAST OF THE REGION...SO
WILL NOT HAVE THE GOOD MASS CONVERGENCE FOR SEVERE STORMS...BUT
PERHAPS ENOUGH FOR ISOLATED TO SCT COVERAGE. A COLD FRONT WILL DROP
INTO NORTHERN WISCONSIN IN THE EVENING...THEN DRIVE INTO CENTRAL
WISCONSIN OVERNIGHT. THIS FRONT WILL END THE SHOWER AND
THUNDERSTORM THREAT...AS WELL AS BRING A RETURN OF NORTHEAST WINDS
AND LESS HUMID CONDITIONS. QUITE A BIT OF LOW STRATO-CU UPSTREAM
BEHIND THE FRONT...AND THINK WILL HAVE A PROBLEM CLEARING ESPECIALLY
WITH THE AMPLE LOW LEVEL MOISTURE LEFT BEHIND FROM THE EXCESSIVE
RAINFALL. LOWS BACK INTO THE 40S NORTH TO THE UPPER 50S SOUTH.
FRIDAY...SURFACE COLD FRONT WILL MOVE FROM CENTRAL WISCONSIN INTO
NORTHERN ILLINOIS AND NORTHEAST IOWA IN THE AFTERNOON. BEHIND THE
FRONT...CANADIAN HIGH PRESSURE WILL BUILD SOUTH ACROSS THE STATE
THROUGH THE DAY. WILL SEE COOLER AND NOTICEABLY DRIER CONDITIONS
ARRIVE...BROUGHT IN BY BRISK NE WINDS. LOOKING UPSTREAM...PLENTY OF
LOW CLOUDS BEHIND THE FRONT OVER SOUTHERN MANITOBA AND ONTARIO...SO
THINK WILL SEE A MOSTLY CLOUDY MORNING...FOLLOWED BY PARTLY SUNNY
CONDITIONS IN THE AFTERNOON. NEXT SYSTEM LOOKS LIKE IT WILL STAY TO
THE WEST AT THIS POINT. HIGHS IN THE 50S NEAR LAKE MICHIGAN...TO
AROUND 70 OVER CENTRAL WISCONSIN.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
MAIN CONCERN FOR THIS PACKAGE WILL BE THE PERIODIC CHANCES FOR
SHOWERS OR THUNDERSTORMS INTO EARLY NEXT WEEK. SOME MODEL DIFFERENCES
NOTED IN TIMING OF THESE SYSTEMS. FIRST SYSTEM EXPECTED TO PUSH
INTO THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL HAVE A SMALL
CHANCE OF SHOWERS ACROSS THE WEST LATE FRIDAY NIGHT...THEN A
CHANCE ACROSS THE ENTIRE AREA SATURDAY. DRY AIR FROM A CANADIAN
HIGH PRESSURE SHOULD LIMIT THE THUNDER POTENTIAL. DID KEEP ISOLATED
THUNDER ACROSS THE FAR WEST AND SOUTH TO MATCH UP WITH LA CROSSE
AND MILWAUKEE.
FOR SATURDAY NIGHT...THERE MAY BE A LINGERING SHOWER SATURDAY
EVENING...THEN THERE WILL BE A CHANCE OF SHOWERS AGAIN LATE
SATURDAY NIGHT ACROSS THE FAR WEST. STRONGER SYSTEM WORKING ACROSS
THE AREA WILL BRING LIKELY CHANCES FOR SHOWERS AND THUNDERSTORMS
SUNDAY INTO SUNDAY NIGHT. WILL CONTINUE TO KEEP A SMALL CHANCES OF
SHOWERS DUE TO DEPARTING SYSTEM...THEN MONDAY NIGHT SHOULD BE MAINLY
DRY.
AN UPPER TROUGH IS THEN EXPECTED TO SWING ACROSS THE AREA TUESDAY
AFTERNOON AND TUESDAY NIGHT...BRINGING ANOTHER CHANCE FOR SHOWERS
AND ISOLATED THUNDERSTORMS. FOR WEDNESDAY...CYCLONIC FLOW WILL GRADUALLY
PUSH EAST. WILL CONTINUE THE SMALL CHANCE FOR SHOWERS. HIGH PRESSURE
THEN BUILDS INTO THE REGION FOR WEDNESDAY NIGHT AND THURSDAY. TEMPERATURES
WILL RUN AT OR BELOW NORMAL DURING THE PERIOD.
&&
.AVIATION...SCT TSTMS WERE DEVELOPING ALONG A COLD FRONT OVER WEST
CENTRAL WISCONSIN EARLY THIS EVG. INSTABILITY IS A BIT WEAKER TO
THE EAST OF THE STORMS...AND CURRENT ACTIVITY WOULD NOT ARRIVE IN
CENTRAL WI UNTIL AFTER SUNSET...SO EXPECT THESE STORMS TO WEAKEN
OR DISSIPATE BEFORE REACHING THE AUW/CWA TAF SITES. HAVE KEPT A
VCSH IN THE THOSE TAF SITES FOR THE EARLY EVG. THE COLD FRONT
WILL CONTINUE TO SAG SOUTH THROUGH THE AREA THIS EVG AND EARLY
FRIDAY MORNING. A SHALLOW COOL AIR MASS IN THE WAKE OF THE FRONT
WILL BE FAVORABLE FOR LOW CLOUD DEVELOPMENT...WITH PSBL IFR CIGS.
LOW CLOUDS SHOULD BREAK UP BY MID-LATE MORNING...BUT STRATOCUMULUS
(MAINLY VFR) WILL LIKELY CONTINUE DURING THE DAY. GUSTY NE WINDS
ARE EXPECTED IN THE FOX VALLEY AND LKSHR AREAS LATE TONIGHT AND
FRIDAY.
KIECKBUSCH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
243 PM CDT WED MAY 2 2012
.SHORT TERM...TONIGHT AND THURSDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW
PRESSURE SITUATED OVER WESTERN KANSAS EARLY THIS AFTERNOON...AND A
COLD FRONT EXTENDING NORTHEAST INTO THE NORTHERN MISSISSIPPI
VALLEY. AN OUTFLOW BOUNDARY FROM THIS MORNINGS CONVECTION HAS
REACHED INTO NORTHERN MISSOURI AND CENTRAL ILLINOIS...THOUGH
CONVECTION HAS YET TO RE-DEVELOP. CLOUD COVER HAS BEEN BUILDING
ACROSS IOWA THIS AFTERNOON WHERE THETAE ADVECTION IS ONGOING...BUT
NO SIGN OF PRECIP HERE EITHER. MEANWHILE...MIXING INTO DRY AIR
ALOFT HAS DISSIPATED THIS MORNINGS CLOUD COVER INTO SCATTERED CU
OVER MUCH OF THE FORECAST AREA. AS A LOW LEVEL JET DEVELOPS AHEAD
THE LOW PRESSURE AND CONVECTION DEVELOPS UPSTREAM...SEVERE WEATHER
CHANCES AND PRECIP AMOUNTS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...PLENTY OF UNCERTAINTY WITH THE DETAILS CONCERNING
POTENTIAL CONVECTION. SHORTWAVE TROUGH OVER MONTANA WILL LIFT NE
OVER NORTH DAKOTA AND INTO SOUTH-CENTRAL CANADA. SW FLOW ALOFT WILL
KEEP LOW PRESSURE OVER THE CENTRAL PLAINS WHILE THE COLD FRONT BECOMES
MORE PERPENDICULAR TO THE LOW LEVEL FLOW OVER IOWA AND INTO
WISCONSIN. AHEAD OF THE SURFACE LOW...A SOUTH TO SOUTHWEST LLJ WILL
DEVELOP LATE THIS AFTERNOON INTO THIS EVENING POINTING INTO IOWA AND
NORTHERN ILLINOIS. GOOD MASS CONVERGENCE ON THE NOSE OF THIS LLJ IN
AN AREA OF MU CAPE 1500-2000 J/KG AND MID-LEVEL LAPSE RATES OF 7 TO
7.5 C/KM SHOULD BE SUFFICIENT TO TRIGGER ELEVATED CONVECTION.
FORWARD PROPAGATING CORFIDI VECTORS WOULD TRACK SUBSEQUENT MCS
ENE...THOUGH AM EXPECTING THE STRONGEST THUNDERSTORMS TO FOLLOW THE
GREATEST INSTABILITY OVER THE SOUTHERN 1/3RD OF THE BADGER STATE AND
NORTHERN ILLINOIS. THE 12Z GFS DOES TRY TO RAM THE LLJ INTO EAST-CENTRAL
WISCONSIN ALONG WITH AMPLE INSTABILITY...BUT THINK THIS IS TOO
AMBITIOUS GIVEN THE WSW FLOW ALOFT AND WITHOUT MUCH MID-LEVEL HEIGHT
RISES. THE FLOW DOES TURN A BIT MORE SW OVERNIGHT AS THE RIGHT REAR
QUAD OF A JET STREAK SHIFTS INTO NORTHERN WISCONSIN...SO AM
EXPECTING TO SEE A MORE NORTHWARD PUSH OF THE NOCTURNAL CONVECTION
ACROSS THE FORECAST AREA AFTER MIDNIGHT. WITH THE ELEVATED
INSTABILITY AXIS REMAINING TO OUR SOUTH...HAVE A HARD TIME GETTING
EXCITED ABOUT SEVERE CHANCES...THOUGH ALWAYS TOUGH TO RULE OUT A
MARGINAL SEVERE STORM ADVECTING INTO THE SOUTHERN FORECAST AREA.
WILL KEEP A MENTION OF SEVERE POSSIBILITIES FOR CENTRAL AND
EAST-CENTRAL WISCONSIN...MAINLY FOR LARGE HAIL...AND STRONG WINDS TO
A LESSER EXTENT. CENTRAL AND EAST-CENTRAL WISCONSIN WILL LIKELY SEE
SUBSTANTIAL RAINFALL...WITH SOME GUIDANCE POINTING TOWARDS WELL OVER
AN INCH OF RAIN. WILL TRY TO CAP IT AROUND THERE...SINCE THE
GREATER INSTABILITY IS SOUTH OF THE FORECAST AREA.
THURSDAY...MORNING CONVECTION MAY VERY WELL BE ONGOING AT THE START
OF THE PERIOD...AS THE RIGHT REAR QUAD OF THE JET STREAK WILL BE
OVERHEAD WHILE 850MB CONVERGENCE WILL BE DRAPED OVER CENTRAL
WISCONSIN. THINK THE MORNING MAY TURN OUT TO BE WETTER THAN MODELS
INDICATE AND WILL KEEP THE NEAR CATEGORICAL POPS IN THE FORECAST.
INSTABILITY WILL BE THE QUESTION MARK FOR THE AFTERNOON...AS THE
WARM FRONT WILL REMAIN STALLED ACROSS THE AREA. THE RIGHT REAR QUAD
OF THE JET STREAK WILL PULL OUT BY THE AFTERNOON...BUT WILL DAYTIME
HEATING LEAD TO CLEARING...DESPITE AMPLE MOISTURE THROUGH THE
COLUMN? THINK ANY BREAKS WILL JUST LEAD TO CU BUILD-UP...RESULTING
IN A MOSTLY CLOUDY DAY REGARDLESS. STILL SOME CAPE TO BE HAD...SO
CANNOT RULE OUT SCATTERED COVERAGE OF SHOWERS AND STORMS THROUGH THE
AFTERNOON. WILL MAKE ONLY COSMETIC CHANGES TO POPS. HIGHS IN THE
LOW TO MID 70S.
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. PCPN CHANCES
WILL BE THE PRIMARY FORECAST ISSUE DURING THIS PERIOD. BUSY WSW
FLOW TO CONTINUE INTO FRIDAY BEFORE MEDIUM RANGE MODELS IN
AGREEMENT WITH BRIEFLY BUILDING AN UPPER RIDGE OVER THE WESTERN
GREAT LAKES REGION SATURDAY INTO SUNDAY. THIS UPPER RIDGE BEGINS
TO FLATTEN LATE IN THE WEEKEND WITH A RETURN TO A SOUTH TO
SOUTHWEST FLOW AHEAD OF A SHORT WAVE TROUGH. MEANWHILE THE
SURFACE BOUNDARY WITH BEST INSTABILITY DROPS WELL SOUTH OF THE
FORECAST AREA LATER FRIDAY INTO FRIDAY NIGHT WITH AN EAST TO
NORTHEAST FLOW AROUND A SURFACE HIGH OVER SOUTHERN CANADA.
WOULD NORMALLY BE AGGRESSIVE WITH ENDING POPS IN THIS
SCENARIO...BUT MDM RANGE MODELS ARE CONSISTENTLY LINGERING A WEAK
H8 BOUNDARY OVER WISCONSIN FOR A POSSIBLE FOCUS OF CONVECTION FOR
AT LEAST A CHANCE OF SHOWERS. THIS H8 BOUNDARY WITH WARMER H8 TEMPS WERE
PRODUCING TOTAL TOTAL VALUES IN THE LOWER 50S...ESPECIALLY TOWARD
WESTERN WISCONSIN. IN ADDITION...BEST UPPER JET DYNAMICS LINGER
ACROSS THE NORTHERN GREAT LAKES REGION TO PROVIDE AREAS OF LIFT.
FOR THE NEW WORK WEEK...A PROGGED DEEPENING UPPER TROUGH WITH
FRONTAL SYSTEM WILL PROVIDE MORE EVEN PCPN CHANCES OF PCPN
THROUGH AT LEAST WEDNESDAY BEFORE A HIGH PRESSURE RIDGE TRIES TO
BUILD IN FROM THE NORTHERN PLAINS AND CANADA. BY MID WEEK NEXT
WEEK PCPN CHANCES MAY BE PRIMARILY DIURNAL VARIETY AS THE UPPER
TROUGH SLOWLY DRIFTS OVER.
&&
.AVIATION...BKN MVFR CIGS OVER NORTHERN WISCONSIN SHOULD STICK
AROUND THROUGH MID-AFTERNOON UNTIL DRIER AIR MIXES AND HELPS ERODE
THE CLOUD COVER. OTHERWISE FOR TONIGHT CIGS AND VSBYS WILL LOWER
FROM VFR TO IFR FROM SOUTHWEST TO NORTHEAST AS AN AREA OF SHOWERS
AND THUNDERSTORMS APPROACHES FROM THE CENTRAL PLAINS. PLENTY OF
UNCERTAINTY HOW THIS AREA OF RAIN WILL EVOLVE...INCLUDING TIMING AND
COVERAGE. THE LATEST THINKING IS THAT CENTRAL AND EAST-CENTRAL
WISCONSIN WILL SEE THUNDERSTORMS ARRIVE LATE THIS EVENING OR EARLY
OVERNIGHT...AND THAT ARRIVAL TIME WILL BE SLIGHTLY POSTPONED FARTHER
NORTH. WIDESPREAD IFR CIGS TO HANG AROUND THROUGH MID-MORNING WITH
A WARM FRONT DRAPED ACROSS THE REGION.
&&
.HYDROLOGY...RAINFALL AMOUNTS OVER CENTRAL AND EAST CENTRAL
WISCOMSIN FROM LAST NIGHS CONVECTION RANGED FROM 0.40 TO 0.80
INCHES. MORE RAIN IS ANTICIPATED TONIGHT INTO THRUSDAY MORNING AS
A WARM FRONT LIFTS INTO SOUTHERN AND CENTRAL WISCONSIN. PWATS
APPROACH 1.50 BY THURSDAY MORNING. AT THIS TIME BETWEEN 1 TO 1.50
INCHES AREAS RAIN IS EXPECTED FROM TONIGHT THROUGH NOON THURSDAY.
DO NOT EXPECT FLOODING AT THESE NUMBERS...BUT IF STORMS BECOME
MORE WIDESPREAD AND CAN TRAIN ALONG THE WARM FRONT...LOCALLY
HIGHER AMOUNTS POSSIBLE. MAIN STEM RIVERS ARE FAIRLY LOW SO
RUNOFF IS NOT EXPECTED TO IMPACT RIVERS...HOWEVER SMALL STREAMS
MAY BEGIN TO BECOME SWOLLEN IF THE HIGHER AMOUNTS VERIFY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/TDH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1136 PM CDT TUE MAY 1 2012
.SHORT TERM...OVERNIGHT
1136 PM CDT TUE MAY 1 2012
STORMS ALONG THE INSTABILITY GRADIENT IN IOWA CONTINUE TO BE THE
DOMINANT STORMS WITH MUCH OF THE EARLIER CONVECTION IN EAST CENTRAL
MINNESOTA/WEST CENTRAL WISCONSIN WEAKENING OVER THE PAST FEW
HOURS. THE LOW LEVEL JET HAS STRENGTHENED AS WELL WHICH HAS LED TO
SOME ISOLATED TO SCATTERED CONVECTION DEVELOPING AHEAD OF THE LINE
OF STORMS THAT EXTENDS FROM SOUTH CENTRAL MINNESOTA INTO NORTH
CENTRAL IOWA. SOME WEAK INSTABILITY OF 500-1000 J/KG OF MUCAPE
CONTINUES TO FEED INTO THE LINE OF STORMS IN NORTH CENTRAL
IOWA...THOUGH THE 02.03Z RUC SHOWS THIS INSTABILITY DECREASING TO
THE EAST OVERNIGHT. CURRENT THINKING IS THAT THE LINE OF STORMS
WILL CONTINUE TO PROPAGATE EAST-SOUTHEAST ALONG THE NOSE OF THE
LOW LEVEL JET OVERNIGHT AND GRADUALLY WEAKEN. THUS...SOME GUSTY
WINDS AND HEAVY RAIN STILL CAN NOT BE RULED OUT ALONG WITH SOME
SMALL HAIL IN ANY ISOLATED STORMS OUT AHEAD OF THE LINE
OVERNIGHT. IF WINDS LIGHTEN UP BEHIND THE RAIN/STORMS...THEN SOME
FOG WILL BE POSSIBLE ACROSS THE REGION TOWARD DAYBREAK TOMORROW
MORNING.
.LONG TERM...SATURDAY THROUGH TUESDAY
255 PM CDT TUE MAY 1 2012
BROAD UPPER LEVEL RIDGING SLATED INTO EARLY NEXT WEEK...VIA THE
LATEST GFS AND ECMWF. BOTH STILL FAVOR BRINGING BITS OF UPPER LEVEL
ENERGY THROUGH THE RIDGE SAT/SUN...WITH SUN/SUN NIGHT HAVING THE
MOST AGREEMENT FOR PCPN CHANCES. SOLUTIONS START TO DIVERGE AS WE
WORK INTO MID WEEK. WILL GO WITH CONSENSUS. TEMPERATURES SHOULD
RETURN TO MORE SEASONABLE...EVEN A BIT BELOW NORMAL READINGS.
&&
.AVIATION...THROUGH 06Z THURSDAY
1136 PM CDT TUE MAY 1 2012
BUSY 24 HOUR PERIOD AT THE TAF SITES WITH STORMS MOVING IN OVER
THE NEXT FEW HOURS. GUSTY WINDS AND HEAVY RAINFALL WILL BE THE
MAIN THREATS AS THE STORMS MOVE IN OVERNIGHT. AHEAD OF THEM...A
1KFT TO 2KFT STRATUS DECK HAS MOVED IN ACROSS THE REGION AND WILL
LIKELY STAY IN PLACE OVERNIGHT. SOME ADDITIONAL FOG COULD DEVELOP
AFTER THE RAIN MOVES THROUGH IF WINDS WEAKEN BEFORE DAYBREAK.
GOING INTO THIS AFTERNOON...MORE THUNDERSTORMS WILL LIKELY DEVELOP
WITH MORE HEAVY RAIN...STRONG WINDS AND HAIL POSSIBLE. AS A COLD
FRONT MOVES THROUGH IN THE EVENING...THE RAIN AND THUNDER SHOULD
COME TO AN END.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
255 PM CDT TUE MAY 1 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM....RIECK
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
233 AM CDT FRI MAY 4 2012
.MESOSCALE DISCUSSION...
815 PM CDT
MAIN CONCERN FOR THE REST OF THE NIGHT IS FLASH FLOOD POTENTIAL.
TRAINING STORMS OVER NORTHEAST DUPAGE AND NORTHERN COOK COUNTY
CONTINUE TO REGENERATE. SOME ALSO PRODUCING SEVERE HAIL. OTHER
SLOW MOVING HEAVY RAIN PRODUCERS OVER BUREAU-LASALLE
COUNTIES...AND YET ANOTHER CLUSTER OF STORMS MOVING IN FROM
EASTERN IA.
SPC ANALYSIS INDICATES RIBBON OF PRECIPITABLE WATER IN EXCESS OF
1.5 FROM WEST CENTRAL TO NORTHEAST ILLINOIS. THIS IS ALSO AN AREA
OF HIGH 850 MOISTURE TRANSPORT. HRRR INDICATING HEAVIEST RAIN IN
THIS CORRIDOR AS WELL. WILL BE ISSUING A FLASH FLOOD WATCH FOR
OVERNIGHT FOR ALL BUT THE NORTH TIER OF COUNTIES.
ALLSOPP
&&
.DISCUSSION...
315 PM CDT
TONIGHT...
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE ONGOING
OVERNIGHT AND IT IS DIFFICULT TO ADD ANY SPECIFICS THIS AFTERNOON
AS TO WHEN THE HEAVIEST OF ACTIVITY WILL POP AND MOVE ACROSS...AS
GUIDANCE HAS BEEN STRUGGLING TO LATCH ONTO A SOLID SOLUTION. THE
HRRR AND RAP HAVE BEEN PRETTY CONSISTENT FROM RUN TO RUN IN
DEVELOPING CONVECTION ACROSS THE NORTHERN BORDER THIS AFTERNOON
AND EVENING...BUT AS THE MODELS HAVE BEEN UNDER PERFORMING THE LAST
FEW DAYS...NOT GOING TO COMPLETELY BITE OFF ON ANY ONE SOLUTION
HAPPENING THIS EVENING...LEADING TO A LOW CONFIDENCE OVERNIGHT
FORECAST. DO BELIEVE THAT THE ONGOING ACTIVITY FROM MKE TO ROUGHLY
MSN WILL TRY TO WORK SOUTH WHILE MOVING EAST...BUT WILL DEFER TO
SPECIFICS THAT FALL WITHIN THE MESO AFD ABOVE. FRONT WILL SLOWLY
BE SAGGING SOUTH ACROSS SOUTHERN WISCONSIN AND WORK INTO ILLINOIS
THROUGH THE OVERNIGHT HOURS. ACTIVITY WILL THEN BE ON THE WANE
AS WE GET CLOSER TO THE MORNING.
THE STRONG WARM AIR ADVECTION THAT SHOT TEMPERATURES INTO THE 80S
TODAY WILL SHIFT SOUTH. WITH THE FRONT DROPPING THROUGH AND ACROSS
CHICAGO...WINDS WILL FLIP AROUND TO THE NORTHEAST AND PULL A
COOLER MARINE AIRMASS ACROSS MUCH OF THE COASTLINE. MODELS CONTINUE
TO SLOW THIS TREND SLIGHTLY OVER PREVIOUS RUNS...BUT DOES CONTINUE TO
KEEP IT DRAPED ACROSS THE AREA. FORECAST SOUNDINGS AND RAW
NUMERICAL GUIDANCE HIGHLIGHTS GOOD INSTABILITY TO PERSIST SOUTH AND
WEST OF THIS FEATURE...THOUGH THE BEST INSTABILITY WILL BE WEST
ACROSS IOWA...AND OVERALL EFFECTIVE SHEAR WILL IS SUGGESTED TO BE AT
OR BELOW 30 KT INTO THE PEAK OF THE AFTERNOON. SPC HAS MOST OF THE
CWA IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW...BUT IT DOES FOLLOW
THE OVERALL LOCATION OF THE FRONT...FAVORING AREAS WITH THE BEST
INSTABILITY. WITH NO REAL FORCING WIGGLING THROUGH THE FLOW
TOMORROW...THE OVERALL THREAT DOES NOT APPEAR TO BE HIGH...BUT
CANNOT RULE OUT THE POSSIBILITY OF SOME UNORGANIZED CELLS DEVELOPING
WITH MARGINAL SEVERE HAIL AND WIND GUSTS.
DID MAKE BIGGER CHANGES TO THE DAYTIME HIGHS ACROSS LAKE AND COOK
COUNTIES. WITH THE FRONT SAGGING SOUTH OF MOST THE METRO INTO THE
EARLY AFTERNOON...SHOULD SEE TEMPS HIT THEIR PEAK IN THE EARLY
AFTERNOON AND THEN FALL. STILL SOME CONSIDERABLE DIFFERENCES BETWEEN
THE MAV AND THE MET THIS AFTERNOON...WITH A 10+ DEGREE DIFFERENCE
BETWEEN THE TWO. THE THOUGHT IS THAT WITH THE FRONT TO THE
SOUTH...MOST COASTAL AREAS /INCLUDING THE CHICAGO METRO/ WILL SEE
HIGHS PEAKING IN THE UPPER 60S TO AROUND 70 BEFORE FALLING INTO THE
AFTERNOON...THOUGH IF MORE RAIN FALLS OVERNIGHT AND KEEPS CLOUDS
IN...MID 60S COULD BE PUSHING IT.
BY THE WEEKEND...UPPER LEVEL RIDGING ACROSS THE FOUR CORNERS REGION
WILL BEGIN TO SHIFT EAST AND OVERHEAD...BUT CONTINUED DISPARITY
BETWEEN LONG RANGE GUIDANCE IS LEADING TO FURTHER LOW END CONFIDENCE
ON PRECIP CHANCES INTO THE NEXT WEEK. TRENDS ARE INDICATING A
WEAK SHORTWAVE ROLLING ACROSS THE RIDGE LATE SUNDAY AND INTO
MONDAY WILL BRING THE NEXT BEST CHANCE FOR SHOWERS. AS THE RIDGE
SLIDES EAST AND A TROUGH MOVES THROUGH...WILL GENERALLY FALL BACK
INTO A COOLER NORTHWESTERLY FLOW REGIME KEEPING DAYTIME HIGHS
CLOSE TO SEASONAL WITH OFF AND ON CHANCES THROUGH THE WEEK.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SHRA/EMBEDDED TS TO CONTINUE FOR A FEW HOURS.
* WINDS BECOMING LIGHT TOWARD DAYBREAK THEN SHIFTING NORTHEAST OR
EAST-NORTHEAST BY MID-MORNING...A FEW GUSTS POSSIBLE AS SHIFT
OCCURS.
* MVFR VSBY POSSIBLE OVERNIGHT AS WINDS DIMINISH.
* MVFR CIGS EXPECTED FOR MUCH OF FRIDAY...WITH IFR POSSIBLE FRIDAY
MORNING.
MDB
//DISCUSSION...UPDATED 06Z...
TOUGH FORECAST THROUGH FRIDAY EVENING...ESPECIALLY IN TERMS OF
CIG/VSBY TRENDS. INITIAL CONCERN IS SHRA/TSRA CONTINUING FOR
ANOTHER FEW HOURS BEFORE SHIFTING OFF TO THE EAST AND SOUTH...WITH
A LONGER DURATION AT GYY. WIND DETAILS WILL BE A BIT TOUGH THROUGH
THE REST OF THE NIGHT WITH A PRIMARILY SOUTHWEST DIRECTION THE
NEXT FEW HOURS BEFORE BECOMING LIGHT AND VARIABLE AS A FRONTAL
BOUNDARY APPROACHES. THIS LIGHT WIND COMBINED WITH ABUNDANT LOW
LEVEL MOISTURE FROM THE RAIN WILL BRING A DECENT CHANCE FOR MVFR
VSBY LATE TONIGHT TOWARDS DAYBREAK. THE FRONT WILL SAG SOUTH OF
THE TERMINALS DURING THE EARLY/MID MORNING HOURS RESULTING IN A
SHIFT TO NORTHEAST OR EAST-NORTHEAST WINDS WHICH WILL CONTINUE
THROUGH THE DAY. WILL NEED TO WATCH POTENTIAL FOR SOME GUSTS TO
DEVELOP RIGHT BEHIND THE FRONT AS WELL.
THE NEXT BIG CONCERN IS CEILINGS. VFR CIGS WILL CONTINUE OVERNIGHT
WITH SOME MVFR BRIEFLY POSSIBLE IN THE HEAVIER PRECIP. ONCE WINDS
TURN NORTHEASTERLY WILL START TO SEE A BETTER POTENTIAL FOR
STRATUS DEVELOPMENT. MVFR LOOKS LIKELY WITH IFR POSSIBLE AS WELL.
ASSUMING MVFR/IFR DOES DEVELOP...THE NEXT CHALLENGE WILL BE CIG
TRENDS THROUGH THE DAY. LATEST GUIDANCE HAS BACKED OFF ON DURATION
OF LOWER CIGS BUT WITH FLOW OFF THE LAKE AM THINKING IMPROVEMENT
MAY BE TOUGH TO COME BY. WILL CONTINUE WITH MVFR CIGS AND HINT AT
IFR FRIDAY MORNING AND AFTERNOON...WITH FORECAST SOUNDINGS SHOWING
CIGS LOWERING AGAIN FRIDAY EVENING. WILL NEED TO KEEP EVALUATING
THIS BUT OVERALL CONFIDENCE IS QUITE LOW SO SOME OVERHAULING OF
THE TAF IS POSSIBLE.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN SHRA/EMBEDDED TS CONTINUING FOR A FEW HOURS.
* MEDIUM-HIGH CONFIDENCE IN WINDS DIMINISHING OVERNIGHT...HIGH
CONFIDENCE IN WINDS SHIFTING TO NORTH EAST OR EAST-NORTHEAST.
MEDIUM-HIGH CONFIDENCE IN TIMING.
* MEDIUM CONFIDENCE MVFR VSBY DEVELOPING OVERNIGHT.
* MEDIUM CONFIDENCE IN MVFR CIGS DEVELOPING FRIDAY MORNING BUT LOW
CONFIDENCE IN IF THEY WILL PERSIST OR IMPROVE DURING THE
AFTERNOON. LOW CONFIDENCE IN IFR POTENTIAL.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE
FRIDAY INTO THE WEEKEND.
WEDNESDAY...CHANCE SHRA. OTRW...VFR.
KJB
&&
.MARINE...
233 AM CDT
I HAVE DECIDED TO ISSUE A DENSE FOG ADVISORY FOR THE OPEN WATERS OF
SOUTHERN LAKE MICHIGAN THROUGH THIS MORNING. SEVERAL NEAR SHORE
OBSERVATIONS AND A SHIP OBSERVATION ACROSS THE NORTHERN SECTIONS OF
THE THE LAKE INDICATED AREAS OF DENSE FOG. I EXPECT THESE AREAS OF
FOG TO BE PUSHED TO THE SOUTHERN END OF LAKE MICHIGAN DURING THE
MORNING HORUS AS A COLD FRONT DROPS DOWN THE LAKE. WINDS BEHIND THIS
FRONT WILL QUICKLY BECOME NORTHERLY UP TO AROUND 20 KT. DRYER AIR
BUILDING IN BEHIND THIS FRONT SHOULD END THE THREAT OF FOG ACROSS
THE NORTHERN HALF OF THE LAKE QUICKLY THIS MORNING.
OTHERWISE...EXPECT WINDS TO BECOME EASTERLY LATER TONIGHT INTO
SATURDAY AS SURFACE HIGH PRESSURE MOVES ACROSS EASTERN ONTARIO.
THERE LOOKS TO BE A PERIOD OF EASTERLY WINDS UP TO AROUND 25 KT ON
SATURDAY AS THE PRESSURE GRADIENT STRENGTHENS OVER THE NORTHERN END
OF THE LAKE. A SURFACE TROUGH OF LOW PRESSURE WILL PUSH ACROSS THE
LAKE ON MONDAY...PRODUCING A WIND SHIFT FROM EAST SOUTHEASTERLY TO
NORTHERLY. THESE NORTHERLY WINDS LOOK TO CONTINUE INTO THE MIDDLE OF
NEXT WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FLASH FLOOD WATCH...ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032 UNTIL 7 AM FRIDAY.
IN...FLASH FLOOD WATCH...INZ001-INZ002 UNTIL 7 AM FRIDAY.
LM...DENSE FOG ADVISORY...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 AM
FRIDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
114 AM CDT FRI MAY 4 2012
.MESOSCALE DISCUSSION...
815 PM CDT
MAIN CONCERN FOR THE REST OF THE NIGHT IS FLASH FLOOD POTENTIAL.
TRAINING STORMS OVER NORTHEAST DUPAGE AND NORTHERN COOK COUNTY
CONTINUE TO REGENERATE. SOME ALSO PRODUCING SEVERE HAIL. OTHER
SLOW MOVING HEAVY RAIN PRODUCERS OVER BUREAU-LASALLE
COUNTIES...AND YET ANOTHER CLUSTER OF STORMS MOVING IN FROM
EASTERN IA.
SPC ANALYSIS INDICATES RIBBON OF PRECIPITABLE WATER IN EXCESS OF
1.5 FROM WEST CENTRAL TO NORTHEAST ILLINOIS. THIS IS ALSO AN AREA
OF HIGH 850 MOISTURE TRANSPORT. HRRR INDICATING HEAVIEST RAIN IN
THIS CORRIDOR AS WELL. WILL BE ISSUING A FLASH FLOOD WATCH FOR
OVERNIGHT FOR ALL BUT THE NORTH TIER OF COUNTIES.
ALLSOPP
&&
.DISCUSSION...
315 PM CDT
TONIGHT...
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE ONGOING
OVERNIGHT AND IT IS DIFFICULT TO ADD ANY SPECIFICS THIS AFTERNOON
AS TO WHEN THE HEAVIEST OF ACTIVITY WILL POP AND MOVE ACROSS...AS
GUIDANCE HAS BEEN STRUGGLING TO LATCH ONTO A SOLID SOLUTION. THE
HRRR AND RAP HAVE BEEN PRETTY CONSISTENT FROM RUN TO RUN IN
DEVELOPING CONVECTION ACROSS THE NORTHERN BORDER THIS AFTERNOON
AND EVENING...BUT AS THE MODELS HAVE BEEN UNDER PERFORMING THE LAST
FEW DAYS...NOT GOING TO COMPLETELY BITE OFF ON ANY ONE SOLUTION
HAPPENING THIS EVENING...LEADING TO A LOW CONFIDENCE OVERNIGHT
FORECAST. DO BELIEVE THAT THE ONGOING ACTIVITY FROM MKE TO ROUGHLY
MSN WILL TRY TO WORK SOUTH WHILE MOVING EAST...BUT WILL DEFER TO
SPECIFICS THAT FALL WITHIN THE MESO AFD ABOVE. FRONT WILL SLOWLY
BE SAGGING SOUTH ACROSS SOUTHERN WISCONSIN AND WORK INTO ILLINOIS
THROUGH THE OVERNIGHT HOURS. ACTIVITY WILL THEN BE ON THE WANE
AS WE GET CLOSER TO THE MORNING.
THE STRONG WARM AIR ADVECTION THAT SHOT TEMPERATURES INTO THE 80S
TODAY WILL SHIFT SOUTH. WITH THE FRONT DROPPING THROUGH AND ACROSS
CHICAGO...WINDS WILL FLIP AROUND TO THE NORTHEAST AND PULL A
COOLER MARINE AIRMASS ACROSS MUCH OF THE COASTLINE. MODELS CONTINUE
TO SLOW THIS TREND SLIGHTLY OVER PREVIOUS RUNS...BUT DOES CONTINUE TO
KEEP IT DRAPED ACROSS THE AREA. FORECAST SOUNDINGS AND RAW
NUMERICAL GUIDANCE HIGHLIGHTS GOOD INSTABILITY TO PERSIST SOUTH AND
WEST OF THIS FEATURE...THOUGH THE BEST INSTABILITY WILL BE WEST
ACROSS IOWA...AND OVERALL EFFECTIVE SHEAR WILL IS SUGGESTED TO BE AT
OR BELOW 30 KT INTO THE PEAK OF THE AFTERNOON. SPC HAS MOST OF THE
CWA IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW...BUT IT DOES FOLLOW
THE OVERALL LOCATION OF THE FRONT...FAVORING AREAS WITH THE BEST
INSTABILITY. WITH NO REAL FORCING WIGGLING THROUGH THE FLOW
TOMORROW...THE OVERALL THREAT DOES NOT APPEAR TO BE HIGH...BUT
CANNOT RULE OUT THE POSSIBILITY OF SOME UNORGANIZED CELLS DEVELOPING
WITH MARGINAL SEVERE HAIL AND WIND GUSTS.
DID MAKE BIGGER CHANGES TO THE DAYTIME HIGHS ACROSS LAKE AND COOK
COUNTIES. WITH THE FRONT SAGGING SOUTH OF MOST THE METRO INTO THE
EARLY AFTERNOON...SHOULD SEE TEMPS HIT THEIR PEAK IN THE EARLY
AFTERNOON AND THEN FALL. STILL SOME CONSIDERABLE DIFFERENCES BETWEEN
THE MAV AND THE MET THIS AFTERNOON...WITH A 10+ DEGREE DIFFERENCE
BETWEEN THE TWO. THE THOUGHT IS THAT WITH THE FRONT TO THE
SOUTH...MOST COASTAL AREAS /INCLUDING THE CHICAGO METRO/ WILL SEE
HIGHS PEAKING IN THE UPPER 60S TO AROUND 70 BEFORE FALLING INTO THE
AFTERNOON...THOUGH IF MORE RAIN FALLS OVERNIGHT AND KEEPS CLOUDS
IN...MID 60S COULD BE PUSHING IT.
BY THE WEEKEND...UPPER LEVEL RIDGING ACROSS THE FOUR CORNERS REGION
WILL BEGIN TO SHIFT EAST AND OVERHEAD...BUT CONTINUED DISPARITY
BETWEEN LONG RANGE GUIDANCE IS LEADING TO FURTHER LOW END CONFIDENCE
ON PRECIP CHANCES INTO THE NEXT WEEK. TRENDS ARE INDICATING A
WEAK SHORTWAVE ROLLING ACROSS THE RIDGE LATE SUNDAY AND INTO
MONDAY WILL BRING THE NEXT BEST CHANCE FOR SHOWERS. AS THE RIDGE
SLIDES EAST AND A TROUGH MOVES THROUGH...WILL GENERALLY FALL BACK
INTO A COOLER NORTHWESTERLY FLOW REGIME KEEPING DAYTIME HIGHS
CLOSE TO SEASONAL WITH OFF AND ON CHANCES THROUGH THE WEEK.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SHRA/EMBEDDED TS TO CONTINUE FOR A FEW HOURS.
* WINDS BECOMING LIGHT TOWARD DAYBREAK THEN SHIFTING NORTHEAST OR
EAST-NORTHEAST BY MID-MORNING...A FEW GUSTS POSSIBLE AS SHIFT
OCCURS.
* MVFR VSBY POSSIBLE OVERNIGHT AS WINDS DIMINISH.
* MVFR CIGS EXPECTED FOR MUCH OF FRIDAY...WITH IFR POSSIBLE FRIDAY
MORNING.
MDB
//DISCUSSION...UPDATED 06Z...
TOUGH FORECAST THROUGH FRIDAY EVENING...ESPECIALLY IN TERMS OF
CIG/VSBY TRENDS. INITIAL CONCERN IS SHRA/TSRA CONTINUING FOR
ANOTHER FEW HOURS BEFORE SHIFTING OFF TO THE EAST AND SOUTH...WITH
A LONGER DURATION AT GYY. WIND DETAILS WILL BE A BIT TOUGH THROUGH
THE REST OF THE NIGHT WITH A PRIMARILY SOUTHWEST DIRECTION THE
NEXT FEW HOURS BEFORE BECOMING LIGHT AND VARIABLE AS A FRONTAL
BOUNDARY APPROACHES. THIS LIGHT WIND COMBINED WITH ABUNDANT LOW
LEVEL MOISTURE FROM THE RAIN WILL BRING A DECENT CHANCE FOR MVFR
VSBY LATE TONIGHT TOWARDS DAYBREAK. THE FRONT WILL SAG SOUTH OF
THE TERMINALS DURING THE EARLY/MID MORNING HOURS RESULTING IN A
SHIFT TO NORTHEAST OR EAST-NORTHEAST WINDS WHICH WILL CONTINUE
THROUGH THE DAY. WILL NEED TO WATCH POTENTIAL FOR SOME GUSTS TO
DEVELOP RIGHT BEHIND THE FRONT AS WELL.
THE NEXT BIG CONCERN IS CEILINGS. VFR CIGS WILL CONTINUE OVERNIGHT
WITH SOME MVFR BRIEFLY POSSIBLE IN THE HEAVIER PRECIP. ONCE WINDS
TURN NORTHEASTERLY WILL START TO SEE A BETTER POTENTIAL FOR
STRATUS DEVELOPMENT. MVFR LOOKS LIKELY WITH IFR POSSIBLE AS WELL.
ASSUMING MVFR/IFR DOES DEVELOP...THE NEXT CHALLENGE WILL BE CIG
TRENDS THROUGH THE DAY. LATEST GUIDANCE HAS BACKED OFF ON DURATION
OF LOWER CIGS BUT WITH FLOW OFF THE LAKE AM THINKING IMPROVEMENT
MAY BE TOUGH TO COME BY. WILL CONTINUE WITH MVFR CIGS AND HINT AT
IFR FRIDAY MORNING AND AFTERNOON...WITH FORECAST SOUNDINGS SHOWING
CIGS LOWERING AGAIN FRIDAY EVENING. WILL NEED TO KEEP EVALUATING
THIS BUT OVERALL CONFIDENCE IS QUITE LOW SO SOME OVERHAULING OF
THE TAF IS POSSIBLE.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN SHRA/EMBEDDED TS CONTINUING FOR A FEW HOURS.
* MEDIUM-HIGH CONFIDENCE IN WINDS DIMINISHING OVERNIGHT...HIGH
CONFIDENCE IN WINDS SHIFTING TO NORTH EAST OR EAST-NORTHEAST.
MEDIUM-HIGH CONFIDENCE IN TIMING.
* MEDIUM CONFIDENCE MVFR VSBY DEVELOPING OVERNIGHT.
* MEDIUM CONFIDENCE IN MVFR CIGS DEVELOPING FRIDAY MORNING BUT LOW
CONFIDENCE IN IF THEY WILL PERSIST OR IMPROVE DURING THE
AFTERNOON. LOW CONFIDENCE IN IFR POTENTIAL.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE
FRIDAY INTO THE WEEKEND.
WEDNESDAY...CHANCE SHRA. OTRW...VFR.
KJB
&&
.MARINE...
223 PM CDT
BROAD LOW PRESSURE WILL EVOLVE EAST ACROSS THE CENTRAL PORTION OF
LAKE MICHIGAN TONIGHT. IN ASSOCIATION WITH THIS FEATURE...CLUSTERS
OF THUNDERSTORMS WILL TRAVERSE ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE...SOME OF THESE POTENTIALLY PRODUCING GUSTY WINDS IN EXCESS OF
35 KTS. GUSTY SOUTHWEST WINDS WILL CONTINUE INTO EARLY THIS EVENING
FROM CHICAGO EASTWARD ACROSS NEARSHORE AREAS...POTENTIALLY
CONTINUING INTO SMALL CRAFT ADVISORY CRITERIA THROUGH 8 OR 9 PM.
THE LOW WILL STEER A COLD FRONT SLOWLY SOUTHWARD ACROSS THE LAKE
TONIGHT INTO FRIDAY MORNING. THIS WILL REACH THE SOUTHERN PORTION OF
THE LAKE BY MIDDAY FRIDAY. NORTHEAST WINDS WILL TURN EAST THIS
WEEKEND AS LOW PRESSURE EVOLVES EASTWARD FROM THE CENTRAL
PLAINS...REACHING THE SOUTHERN GREAT LAKES TO MIDDLE OHIO VALLEY BY
SOMETIME EARLY NEXT WEEK.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FLASH FLOOD WATCH...ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032 UNTIL 7 AM FRIDAY.
IN...FLASH FLOOD WATCH...INZ001-INZ002 UNTIL 7 AM FRIDAY.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
336 AM CDT FRI MAY 4 2012
.SHORT TERM.../TODAY/
WEAK SYNOPTIC SCALE FORCING ASSOCIATED WITH ELONGATED SHORT WAVE
FROM WRN GREAT LAKES INTO TX PANHANDLE CONTINUES TO COMBINE WITH
MOISTURE CONVERGENCE ALONG 305K ISENT SURFACE TO PRODUCE SCATTERED
THUNDERSTORMS ACROSS SRN IA. ORIGINALLY THOUGHT MO MCS WOULD
INTERCEPT INFLOW KEEPING CONVERGENCE TO OUR SOUTH...HOWEVER LARGER
SCALE FORCING HAS APPARENTLY ALLOWED MORE DEVELOPMENT FARTHER
NORTH. ELEVATED CAPES UP TO 2500 J/KG AND LITTLE CINH WITH ADEQUATE
EFFECTIVE SHEAR CONTINUE TO PRODUCE SUPERCELLS WITH HEAVY RAIN
POTENTIAL. EXPECT BOTH SEVERE AND HEAVY RAIN THREATS TO DIMINISH BY
SUNRISE HOWEVER AS 305K FLOW CONTINUES TO VEER AND WEAKEN...REDUCING
CONVERGENCE.
QUESTION THEN TURNS TO REDEVELOPMENT LATER IN THE DAY. NAM AND GFS
BOTH BUILD ANOTHER ROUND OF 2500-3000 J/KG MLCAPES AND LITTLE CINH
INTO THE HEART OF IA AS WARM FRONT GRADUALLY SURGES BACK NORTHWARD
INTO THE STATE...CONNECTING TO WEAK SURFACE WAVE OVER SRN SD.
CONVERGENCE WITH THIS FEATURE WILL BE WEAK BUT HRRR AND NMM WRF TRY
TO DEVELOP ISOLATED CONVECTION DURING PEAK HEATING. NOT COMFORTABLE
GOING DRY SO HAVE GONE WITH SLIGHT CHANCES DURING THE AFTERNOON.
BETTER SVR THREAT WOULD BE OVER NRN IA WHERE 0-6KM SHEAR IS THE
HIGHEST. IF ANY STORMS DO FORM THEY WOULD AGAIN BE SLOW MOVING WITH
WEAK H85/H3 WINDS AND B2K SUPERCELL MOTION. LIGHT WINDS...VERY
SEASONALLY HIGH PWS AND DEEP WARM CLOUD DEPTHS COULD ALSO PRODUCE
ISOLATED HEAVY RAINS IF ANYTHING DOES DEVELOP.
.LONG TERM.../TONIGHT THROUGH THURSDAY/
LONG TERM FORECAST IS A CHALLENGE ESPECIALLY EARLY IN THE PERIOD
UNTIL THE SYNOPTIC FRONT MOVES THROUGH SUNDAY NIGHT INTO MONDAY.
MESOSCALE FEATURES WILL BE A MAJOR FACTOR UNTIL THEN...SO WILL
HAVE TO GIVE DUE CONSIDERATION TO THEM IN ADDITION TO SYNOPTIC
FEATURES. IN ADDITION...SEVERE WEATHER AND HEAVY RAIN WILL REMAIN
A THREAT UNTIL THE SYNOPTIC FRONT MOVES THROUGH LATE THIS
WEEKEND.
FOR TONIGHT...ANY STORMS THAT DO DEVELOP WILL HAVE THE POTENTIAL
TO BE SEVERE. IN ADDITION...THEY WOULD BE EFFICIENT RAINFALL
PRODUCERS. FORECAST SOUNDINGS INDICATE PRECIPITABLE WATER VALUES
WILL BE AS HIGH AS THE 1.5 TO 1.75 RANGE TONIGHT...WHICH WOULD BE
BETWEEN THE 99TH PERCENTILE AND THE RECORD HIGH VALUES FOR THIS
TIME OF YEAR. IN ADDITION...COMPARISON OF MEAN STORM MOTION AND
CORFIDI VECTORS INDICATE THAT ANY STORMS WHICH DO DEVELOP WILL
EITHER BE SLOW MOVERS OR WILL TRAIN. THUS HAVE ADDED MENTION OF
HEAVY RAIN IN TONIGHT/S FORECAST. WILL LEAVE THE DECISION OF A
POTENTIAL FLASH FLOOD WATCH WITH THE DAY SHIFT.
THUNDERSTORM CHANCES WILL BE LOWER DURING THE DAY ON
SATURDAY...BUT WILL RETURN AGAIN SATURDAY NIGHT. ALTHOUGH
FORECAST SOUNDINGS INDICATE LOWER PRECIPITABLE WATER VALUES THAN
THOSE EXPECTED FOR TONIGHT...HEAVY RAIN WILL AGAIN BE A
POSSIBILITY IN ADDITION TO SEVERE WEATHER. OF COURSE...MESOSCALE
FEATURES MAY HELP ENHANCE ANY THUNDERSTORM ACTIVITY.
UPPER AIR PATTERN AND SENSIBLE WEATHER UNDERGO A SIGNIFICANT
SHIFT SUNDAY NIGHT INTO MONDAY...AS THE SYNOPTIC FRONT MOVES
THROUGH AND THEN AN UPPER LEVEL LOW SHIFTS SOUTHWARD FROM CANADA
TO THE NORTHERN CONUS. OVERALL...WEATHER WILL BECOME DRIER BUT
SOME PCPN IS POSSIBLE IN ASSOCIATION WITH THE UPPER LEVEL LOW. AT
THIS TIME THE BEST CHANCES FOR PCPN WOULD BE TO OUR NORTH.
&&
.AVIATION...04/06Z
THUNDERSTORM CHANCES CONFINED TO MAINLY KOTM THROUGH THE NEXT 6 TO
10 HOURS...WITH SOME PATCHY LIGHT FOG POSSIBLE AT OTHER TAF SITES AS
SFC AND LOW LEVEL MOISTURE REMAINS HIGH WITH LIGHT WINDS. EXPECT
BREAK IN ANY SHRA/TSRA ACTIVITY AGAIN DURING THE BULK OF THE
DAYLIGHT HOURS...WITH THUNDERSTORM ACTIVITY EXPECTED TO DEVELOP
TOWARD THE EARLY EVENING/OVERNIGHT HOURS AGAIN FRIDAY. HAS BEEN
REALLY HARD TO NAIL PLACEMENT DOWN...SO HAVE STUCK WITH SOME VCSH
MENTIONS IN THE AREAS THAT SEEM MORE CONDUCIVE TO CONVECTIVE
DEVELOPMENT AT THIS TIME.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 9 AM CDT THIS MORNING FOR APPANOOSE-
DAVIS-MAHASKA-MONROE-WAPELLO.
&&
$$
SHORT TERM...SMALL
LONG TERM...ZOGG
AVIATION...BEERENDS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
310 AM EDT FRI MAY 04 2012
.Short Term (Today through Saturday)...
Issued at 310 AM EDT May 4 2012
Upper air analysis is showing myriad little ripples in the flow
moving overhead throughout this short term period. The most
significant looking wave will pass overhead early Saturday, ending
up to our south by Saturday evening. At the surface, a weak
east-west cold front reaching from the central Plains into the Great
Lakes this morning will settle southward, landing somewhere in the
vicinity of the Ohio River/I-64 corridor by Saturday morning, and
then getting hung up there for the rest of the day.
Thunderstorm chances will gradually increase as the cold front
approaches, and will occasionally be enhanced by any weak upper
waves moving through. In the forecast we will slowly ramp
thunderstorm chances up from slight chance this morning to chance
this afternoon. Tonight looks like the best shot at rain, with
moisture pooling ahead of the front to the tune of 1.5 inch
precipitable waters, so will go with likelies north and central and
chance south. Over the course of the day on Saturday will push the
rain chances south as the day progresses, arriving at just a slight
chance of lingering showers or storms by Saturday evening.
With more clouds expected today than we have been seeing recently,
there is some question as to how unstable we will be able to get
this afternoon. Nevertheless, there could be enough surface based
instability and wind aloft to get a few strong to severe storms
going. Hail would be the primary threat, with gusty winds a
secondary possibility.
Severe weather looks less likely for Saturday, with much weaker wind
fields and less instability thanks to more widespread clouds and
precipitation in the morning. Also, if the timing of the Saturday
upper wave is correct, much of the region will be behind the wave by
evening.
Will stick with lower to middle 80s for highs today and Saturday
with clouds and chance of showers. We will still be ahead of the
cold front tonight so it should be another muggy, warm night with
lows again in the 60s.
.Long Term (Saturday night through Thursday)...
Issued at 310 AM EDT May 4 2012
The back-door front is still on track to slide southwest across the
forecast area and stall Saturday night and Sunday. As mentioned in
the previous forecast, the upper-level ridge axis will be directly
overhead Sunday, with indications of weak subsidence. This will act
to limit widespread convection, with only isolated thunderstorms
expected. Temperatures Sunday morning in the low to mid 60s will
give way to low and mid 80s for highs.
Latest guidance indicates flow aloft will become generally zonal
Monday and Tuesday with troughing becoming established across the
East Coast by Thursday as a strong shortwave moves through the Great
Lakes. At the surface, a weak surface low will move across the
Plains to the mid Mississippi River Valley by Monday morning and
continue progressing eastward, reaching the northeast CONUS by
Wednesday morning.
This pattern change will cause our stalled frontal boundary to
retreat northward as a warm front early Monday, with a short break
in precipitation until a cold front pushes through the region later
in the day Monday and Monday night. This will be the best chance to
experience numerous showers and thunderstorms. At this time, the
dynamics with this frontal passage do not appear too favorable for
organized severe weather, but some strong storms are still possible
as moderate instability will be present. Showers and a few lingering
storms will exit Tuesday morning as the cold front moves east. Highs
in the lower 80s Monday will give way to cooler temps Tuesday, with
highs generally in the mid 70s anticipated.
With a strong trough developing over the East Coast and surface high
pressure building across our region Tuesday night through Thursday,
will proceed with a generally dry forecast and cooler temperatures
as northerly flow will dominate. Could see some showers Wednesday
afternoon as models hint at a vort max tracking through the Ohio
Valley on the back side of the upper-level trough. Overall moisture
appears fairly limited, so will just carry a small chance of rain at
this time. Temperatures will continue to trend cooler with highs
Wednesday and Thursday ranging from the upper 60s to low 70s.
Overnight lows will have a similar trend, with lower 50s expected by
Wednesday night.
&&
.Aviation (06Z TAF Issuance)...
Updated at 120 AM EDT May 4 2012
A weak east-west cold front to our north will slowly settle
southward over the course of this TAF period, arriving somewhere in
the vicinity of the Ohio River by Saturday morning. As this front
approaches, thunderstorm chances will steadily increase. Rather
than have thunder in the TAFs for most of the forecast period, will
hold off for now and see how development progresses to our north.
The exception will be at SDF and LEX after 00Z tonight since the
front will be quite close by then and there is some semblance of
model agreement that thunderstorms will be in the area.
Another challenge is the possibility of sub-VFR ceilings by dawn
this morning, especially at BWG. Latest RR is showing a large area
of LIFR ceilings swelling northward from the Chattanooga area into
much of central Kentucky by 10Z. A look at current obs shows that
the RR actually has a very good handle on the ceilings in the
Chattanooga area at initialization, which creates some cause for
concern. For now will give a nod to the model and bring in a TEMPO
BKN MVFR ceiling at BWG for 10Z-14Z, and will continue to monitor to
see how things develop.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......13
Long Term........MJP
Aviation.........13
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
125 AM EDT FRI MAY 04 2012
.Short Term (Today through Friday)...
Issued at 300 PM EDT May 3 2012
Upper low over Tennessee has managed to sling a fairly extensive
cloud shield into Kentucky, but precip has had a tough time holding
together. The cloud cover has kept the environment from
destabilizing, and kept a lid on any convective development. However
it has warmed up enough along the river to generate a decent cu
field. With temps in the lower/mid 80s and another hour or two of
heating left, will hold on to the slight chance POP north of the
Parkways. Better chances will be found to the south with the
scattered showers that are ongoing.
Precip chances will end by sunset with the loss of daytime heating.
Will be another warm and muggy night, with lows generally in the mid
60s, but upper 60s in the urban heat island near Louisville.
Low-confidence forecast for Friday as we are hard pressed to pick
out the upper impulses that will ride over the top of the flat
ridge. Plenty of resulting uncertainty regarding when and where
these impulses will trigger convection. Therefore will ramp POPs up
to a high chance for the afternoon and evening, but cannot yet
refine it further. Atmosphere will be moderately unstable and
weakly/marginally sheared. GFS soundings show a bit more shear and
instability than the NAM, but also a decent cap around 750mb. Friday
night precip chances still ride on the ability for convection to
develop over Illinois in the afternoon, and then dive SE into the
Ohio Valley. SPC Day 2 outlook has a slight risk, with the main
threat looking like hail and wind in the late afternoon and evening.
.Long Term (Saturday through Thursday)...
Issued at 315 PM EDT May 3 2012
Weak northwest mid level flow will be over the area on Wednesday
with ridge axis dominating over the southern Plains. Ongoing
convection Saturday morning will likely be on the decrease as wave
rounding the periphery of the ridge slides southeast. Big question
will be how long convective debris hangs over the area and the
resultant impact on afternoon destabilization. Some model solutions
suggest another wave arriving in the afternoon evening, along with
chances that a weak back door cold front will approach from the
north toward the afternoon and evening. Overall, still going with
scattered showers and thunderstorms through the day on Saturday.
Still expect we could see a few strong pulse storms with small hail
and some gusty winds, however shear is too weak to anticipate any
more organized threat. Between Saturday morning convection and
afternoon/evening diurnal convection, most places should expect
rain, however the day should not be a washout. Highs are tricky and
will depend on convective cloud cover. This is evident in wide
spread in guidance. Have gone near the cooler guidance with highs in
the mid 80s.
Back door cool front will continue to slide southwest across the CWA
and stall out Saturday night and Sunday. Will keep Iso-Sct coverage
over the area during this time with the best shot west of I-65
Sunday. Ridge axis will be more over the area during this time and
weak subsidence inversion should limit coverage to a degree.
Anticipating low in the low to mid 60s Saturday night with highs
Sunday in the low to mid 80s.
As we move into the new work week mid level flow will flatten out in
response to a potent shortwave diving into the northern Plains. Weak
surface low will move across the Plains to the middle Mississippi
River valley by Monday morning. This will lift the stalled frontal
boundary back north as a warm front. Will leave iso-sct pops in the
forecast for Sunday evening as isentropic lift over the front could
spark some convection. Will likely be a lull between warm frontal
precip and the arrival of more widespread convection ahead of
surface low and associated cold front. Monday and Monday evening
look to be the best days to receive numerous showers and scattered
storms. At this point, warm sector does not appear to favor more
than a few strong storms as moderate instability combines with weak
shear. Showers and a few lingering storms will exit on Tuesday as
cold front moves east. Highs in the lower 80s Monday will cool off
to highs in the mid and upper 70s on Tuesday. Expect overnight lows
in the low to mid 60s.
Models generally agree on some degree of a strong trough developing
over the eastern CONUS from Tuesday night through the end of the
forecast period. Amount of low level moisture behind the front is in
question and therefore forecast remains mostly dry during this time.
However, temperatures will continue to trend cooler with highs on
Wednesday and Thursday down into the low to mid 70s. Lows by
Wednesday night should be down to the mid 50s.
&&
.Aviation (06Z TAF Issuance)...
Updated at 125 AM EDT May 4 2012
A weak east-west cold front to our north will slowly settle
southward over the course of this TAF period, arriving somewhere in
the vicinity of the Ohio River by Saturday morning. As this front
approaches, thunderstorm chances will steadily increase. Rather
than have thunder in the TAFs for most of the forecast period, will
hold off for now and see how development progresses to our north.
The exception will be at SDF and LEX after 00Z tonight since the
front will be quite close by then and there is some semblance of
model agreement that thunderstorms will be in the area.
Another challenge is the possibility of sub-VFR ceilings by dawn
this morning, especially at BWG. Latest RR is showing a large area
of LIFR ceilings swelling northward from the Chattanooga area into
much of central Kentucky by 10Z. A look at current obs shows that
the RR actually has a very good handle on the ceilings in the
Chattanooga area at initialization, which creates some cause for
concern. For now will give a nod to the model and bring in a TEMPO
BKN MVFR ceiling at BWG for 10Z-14Z, and will continue to monitor to
see how things develop.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......RAS
Long Term........BJS
Aviation.........13
AREA FORECAST DISCUSSION
NWS HASTINGS NE
356 AM CDT FRI MAY 4 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT. AREAS OF FOG DEVELOPED
EARLY THIS MORNING IN PRESENCE OF LLVL MOISTURE AND NEARLY CALM OR
LIGHT EASTERLY WINDS. RUC13 SEEMS TO BE HANDLING THE VSBYS THE BEST
AND SUGGESTS PRETTY MUCH OUR ENTIRE CWA MAY BE UNDER INFLUENCE OF
DENSE FOG BY MORNING AND HAVE ISSUED DENSE FOG ADV UNTIL 8 AM FOR
ALL BUT OUR FAR NORTHERN COUNTIES WHERE TEMP/DP SPREAD IS
CURRENTLY GREATER...AND OUR FAR EASTERN CWA WHERE HIGH CLOUD COVER
FM CONVECTION TO OUR SE MAY HOLD UP VSBYS. WILL CONTINUE TO
MONITOR TRENDS EARLY THIS MORNING AS TO WHETHER HEADLINE NEEDS TO
BE EXPANDED OR NOT.
LOOKING FOR FOG TO BURN OFF AFTER DAYBREAK WITH DAYTIME
HEATING...THEN MUCH OF THE DAY IS LOOKING DRY. PATTERN ALOFT
FEATURED SOUTHWESTERLY FLOW WITH MID/UPPER TROUGH ORIENTED FM
ALBERTA INTO THE NORTHERN ROCKIES. JET STREAK NOSES INTO THE NC
ROCKIES TODAY WHILE A SERIES OF SUBTLE SHORTWAVE LIFT FM BASE OF
TROUGH. AT THE SURFACE WARM FRONT LIFTS INTO NC NEB THIS AFTERNOON
AND CONVERGENCE ALONG FRONT AND ENERGY ASSOCIATED WITH WAVES IS
EXPECTED TO INITIATE CONVECTION IN VCNTY OF FRONT. SREF INDICATES
AN AXIS OF INSTABILITY MUCAPES OF 4000 J/KG ACROSS EASTERN NEB/KS
WITH EFFECTIVE SHEAR AROUND 30KTS IN OUR CWA....INCREASING TO NEAR
50 KTS NEAR THE FRONTAL BOUNDARY JUST TO OUR NORTH. INITIATION
LOOKS TO BE JUST TO OUR NORTH ALONG THE FRONT FOR MAIN FOCUS WITH
ACTIVITY POTENTIALLY REACHING OUR NORTHERN ZONES TONIGHT. SOME
QUESTION AS TO WHETHER ACTIVITY MAY FIRE TO THE WEST NEAR THE DRY
LINE OR PERHAPS A DIFFERENTIAL HEATING BOUNDARY AS OCCURRED
YESTERDAY. FOR NOW WILL MAINTAIN MAIN FOCUS ALONG THE WARM FRONT
FOR TONIGHT...WITH SEVERE STORMS POSSIBLE. ALSO FOR TONIGHT...LLVL
FLOW REMAINS FM A LIGHT EASTERLY DIRECTION AS BOUNDARY SAGS SOUTH.
LOOKING AT POTENTIAL FOR FOG DEVELOPMENT AGAIN OVERNIGHT.
ON SATURDAY...WARM FRONT LIFTS NORTH IN AFTERNOON THEN COOL FRONT
PUSHES SOUTH SATURDAY NIGHT. LOOKING AT FAIRLY DECENT CHCS FOR
CONVECTION SATURDAY NIGHT AS THE STRONGER FRONT MOVES THROUGH AS
UPPER TROUGH CROSSES THE DAKOTAS. SEVERE STORMS ARE PROBABLE AGAIN
IN PRESENCE OF HIGH INSTABILITY AHEAD OF APPROACHING BOUNDARY AND
INCREASING SHEAR AS FRONT APPROACHES. COLD FRONT REACHES ALL BUT OUR
FAR SOUTHEAST CWA BY SUNDAY MORNING...AND HAVE LINGERED SOME
THUNDER INTO SUNDAY IN THIS AREA...WITH JUST RAIN SHOWERS FARTHER
NORTH AS INSTABILITY DIMINISHES.
COOLER...BREEZY/WINDY CONDITIONS SETTLE IN ON SUNDAY BEHIND THE
BOUNDARY WITH PCPN CHCS DECREASING DURING THE DAY. DRY WEATHER IS
FORECAST SUNDAY NIGHT.
.LONG TERM...MONDAY THROUGH THURSDAY.
BY MONDAY...AN UPPER LEVEL RIDGE ACROSS THE EASTERN HALF OF THE
CONUS WILL BEGIN TO BREAK DOWN AS AN UPPER LEVEL TROUGH PUSHES
ACROSS THE CENTRAL CONUS. RIDGING WILL PUSH ACROSS THE NORTHWEST
COAST BEHIND THE TROUGH...WHILE A CLOSED UPPER LOW WILL PUSH ACROSS
THE SOUTHEAST ASSOCIATED WITH THE BASE OF THE TROUGH. AT THE SURFACE
LOW PRESSURE IS EXPECTED TO SHIFT ACROSS SOUTHERN CANADA WHILE HIGH
PRESSURE REMAINS CENTERED ACROSS THE ROCKIES.
THE UPPER LEVEL TROUGH IS EXPECTED TO DIVE SOUTHEAST ACROSS THE OHIO
RIVER VALLEY IN THE LONG TERM PERIOD. WITH THE SURFACE LOW FOLLOWING
SUIT...HIGH PRESSURE FROM CANADA WILL SLIDE SOUTHWARD INTO THE
CENTRAL PLAINS. COOLER 850 MB TEMPERATURES WILL ALSO SHIFT
SOUTHWARD...INDICATING COOLER HIGH TEMPERATURES IN THE LONG TERM
PERIOD. HOWEVER...850 MB TEMPERATURES STILL REMAIN NEAR 10 TO 13
DEGREES CELSIUS...SUGGESTING UPPER 60S TO LOWER 70S FOR HIGHS.
AT THIS TIME...THERE IS SOME DISCREPANCY AMONG MODELS REGARDING
PRECIPITATION CHANCES IN THE LONG TERM PERIOD. THE GFS REMAINS DRY
THROUGHOUT THE ENTIRE PERIOD...WHILE THE ECMWF TRIES TO GENERATE
SLIGHT POPS ACROSS THE PLAINS SPECIFICALLY TUESDAY. THE ECMWF TRIES
TO GENERATE A FEW SCATTERED POPS ACROSS THE FORECAST AREA...AS
COOLER AIR SLIDES SOUTH ALONG THE BACKSIDE OF THE TROUGH. ASSOCIATED
WITH THE LOCATION OF THE RIGHT ENTRANCE REGION OF UPPER LEVEL
JET...ENOUGH LIFT COULD BE POSSIBLE DURING THE AFTERNOON ON TUESDAY.
HOWEVER...BOTH MODELS SUGGEST DEWPOINTS IN THE 35 TO 40 DEGREE
RANGE. AT THIS POINT...DECIDED TO KEEP THE LONG TERM DRY UNTIL
MODELS CAN COME INTO BETTER AGREEMENT ON MOISTURE POTENTIAL AND
LOCATION OF THE UPPER LEVEL JET.
&&
.AVIATION...KGRI TAF UPDATE. FOG CONTINUES TO EXPAND ACROSS THE
FORECAST AREA. VISIBILITY RESTRICTIONS ARE EXPECTED TO FLUCTUATE
BETWEEN ONE QUARTER MILE AND 1 MILE AT TIMES. WITH LIGHT AND
VARIABLE WINDS AND AMPLE MOISTURE IN THE AREA...FOG MAY BE SLOW TO
DISSIPATE UNTIL SUNRISE THIS MORNING.
PREV DISCUSSION... /ISSUED 1241 AM CDT FRI MAY 4 2012/
AVIATION...06Z KGRI TAF. AS A SURFACE TROUGH PASSES THROUGH THE
REGION OVERNIGHT TONIGHT...WINDS WILL LIKELY REMAIN LIGHT AND
VARIABLE...TO EVEN CALM AT TIMES. AS A RESULT...COMBINED WITH
AMPLE MOISTURE IN THE REGION...FOG DEVELOPMENT WILL REMAIN
POSSIBLE ACROSS THE TAF SITE. FOG THAT DEVELOPS WILL LIKELY BE
PATCHY IN NATURE. NEIGHBORING SITES HAVE HAS EXPERIENCED
VISIBILITY REDUCTIONS FROM 5 SM TO EVEN A QUARTER OF A MILE IN
SOME AREAS. AT THIS TIME...DECIDED TO LEAVE MENTION OF AT LEAST
IFR VISIBILITIES AND CEILINGS IN THE TEMPO GROUP...AS MODEL
SOUNDINGS INDICATE FOG COULD EASILY REACH THE TAF SITE. BESIDES
FOG POTENTIAL THIS MORNING...CLOUD BASES SHOULD REMAIN FAIRLY HIGH
WITH THE POSSIBILITY FOR CUMULUS DEVELOPMENT THIS AFTERNOON AS
TEMPERATURES CLIMB WELL INTO THE 80S. THERE REMAINS THE
POSSIBILITY FOR THUNDERSTORMS DURING THE EVENING AND OVERNIGHT
HOURS TONIGHT...BUT EXPECT THEM TO BE SCATTERED IN NATURE SO WILL
LEAVE OUT OF THE TAF FOR NOW.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 8 AM CDT THIS MORNING FOR NEZ041-
046>049-060>064-072>077-082>087.
KS...DENSE FOG ADVISORY UNTIL 8 AM CDT THIS MORNING FOR KSZ005-006-
017-018.
&&
$$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
105 AM EDT FRI MAY 4 2012
.SYNOPSIS...
WARM BUT UNSETTLED WEATHER WILL CONTINUE THROUGH TONIGHT AND INTO
FRIDAY. HIGH PRESSURE WILL THEN BUILD INTO THE REGION FOR THE
WEEKEND...BRINGING A RETURN TO FAIR WEATHER AND MORE SEASONABLE
TEMPERATURES.
&&
.NEAR TERM /THROUGH TODAY/...
THROUGH THE EARLY MORNING HOURS...AN ORGANIZED LINE OF SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO PUSH EAST OF THE CWA. THE HRRR HAS
NOT PERFORMED WELL WITH THIS...BUT THE 00Z NAM/RGEM TO APPEAR TO
SHOW SOME SKILL IN CAPTURING THIS. BLENDING THIS WITH SATELLITE
AND RADAR TRENDS...ONLY SEE A CHANCE OF ADDITIONAL SHOWERS IN MOST
LOCATIONS OUTSIDE OF THIS EXITING LINE. THE EXCEPTION TO THIS IS
IN FAR WESTERN LOCATIONS...WHERE BOTH NAM/RGEM DO BRING IN MORE
QPF LATER TONIGHT. THIS IS SUPPORTED BY RADAR TRENDS...WHICH SHOWS
SHOWERS ACROSS SOUTHERN ONTARIO...POISED TO TRACK INTO THE NIAGARA
FRONTIER THROUGH DAYBREAK.
ON FRIDAY...ANY LINGERING NOCTURNAL CONVECTION SHOULD EXIT THE AREA
FAIRLY QUICKLY DURING THE EARLY MORNING HOURS. ONCE THIS IS
GONE...ANY LINGERING CHANCES WILL BE DRIVEN BY THE PASSAGE OF THE
LOW AND ITS TRAILING COLD FRONT...WHICH NOW APPEARS AS IF IT WILL
MOVE THROUGH THE AREA MORE QUICKLY THAN BEFORE. COUPLING THIS
QUICKER MOVEMENT WITH WHAT SHOULD BE A GREATER DEGREE OF CLOUD COVER
AND SIGNIFICANTLY LOWER AMOUNTS OF INSTABILITY COMPARED TO
TODAY...FEEL THAT CONVECTIVE CHANCES WILL BE LOWER OVERALL...ALONG
WITH A MUCH REDUCED SEVERE THREAT COMPARED TO HOW THINGS LOOKED JUST
A FEW DAYS AGO. FOR THESE REASONS...HAVE TRIMMED POPS BACK TO THE
CHANCE CATEGORY AFTER THE FIRST FEW HOURS OF TOMORROW MORNING...WITH
THESE THEN DIMINISHING FROM NORTHWEST TO SOUTHEAST IN THE AFTERNOON
FOLLOWING THE PASSAGE OF THE MAIN COLD FRONT.
TEMPERATURE-WISE...EXPECT A WARM AND SOMEWHAT HUMID NIGHT WITH THE
AREA REMAINING IN THE WARM SECTOR TONIGHT...WITH OVERNIGHT LOWS
GENERALLY IN THE LOWER TO MID 60S. DAYTIME HIGHS ON FRIDAY WILL THEN
GENERALLY RANGE THROUGH THE 70S...A LITTLE COOLER THAN TODAY GIVEN
THE INCREASED CLOUD COVER AND SLIGHTLY COOLER AIR WORKING IN BEHIND
THE COLD FRONT.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
MODELS HAVE COME INTO SOLID AGREEMENT ON THE POSITION/TIMING OF A
COOL FRONT THAT WILL DROP SOUTH ACROSS LAKE ONTARIO AND INTO
WESTERN/CENTRAL NEW YORK STARTING FRIDAY NIGHT. AS THIS COOL AND
STABLE AIRMASS SURGES SOUTHWARDS EXPECT ANY LINGERING CONVECTION TO
DISSIPATE AND/OR SLIDE SOUTH INTO PENNSYLVANIA WITH THE FRONTAL
BOUNDARY. ALTHOUGH THE AIRMASS MOVING IN WILL DRY OVER
TIME...LINGERING LOW LEVEL MOISTURE COMBINED WITH UPSLOPE NORTHERLY
FLOW WILL LIKELY KEEP LOW CLOUDS LOCKED IN ACROSS THE FORECAST AREA
THROUGH THE NIGHT AND AT LEAST THROUGH THE FIRST HALF OF
SATURDAY...LEADING TO WHAT SHOULD BE A RATHER DREARY...DRIZZLY
MORNING ON SATURDAY. EARLY MORNING LOWS IN THE LOW TO MID 50S SHOULD
STRUGGLE INTO THE LOW TO MID 60S THE AFTERNOON...PROVIDED THE DRY
AIR MIXES ALL THE WAY TO THE SURFACE AND CLOUD COVER GRADUALLY
BREAKS UP AS PROGGED.
THE CLEARING TREND SHOULD CONTINUE THROUGH SATURDAY NIGHT AS A COOL
AND DRY DOME OF HIGH PRESSURE BUILDS ACROSS THE REGION OUT OF CANADA
AHEAD OF A BROAD UPPER LEVEL RIDGE OVER THE GREAT LAKES. EXPECT A
COOL NIGHT SATURDAY NIGHT WITH TEMPERATURES COOLING INTO THE LOWER
40S UNDER MOSTLY CLEAR SKIES AND LIGHT WINDS. THE FAIR WEATHER WILL
CONTINUE THROUGH THE BALANCE OF THE WEEKEND UNDERNEATH THE HIGH WITH
TEMPERATURES RUNNING RIGHT AROUND NORMAL...IN THE LOW TO MID
60S...WHICH WILL SEEM DOWNRIGHT CHILLY COMPARED TO THE CURRENT BALMY
WEATHER.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE FIRST HALF OF NEXT WEEK WILL FEATURE A TRANSITION BACK INTO A
MORE UNSETTLED PATTERN FOR WESTERN AND CENTRAL NEW YORK. THE RIDGE
OF HIGH PRESSURE EXTENDING OVER THE REGION FROM CANADA WILL START TO
SLIDE EAST ON MONDAY AS A VIGOROUS UPPER LEVEL LOW/TROUGH DIGS INTO
THE UPPER MIDWEST. THIS UPPER TROUGH WILL AID IN SURFACE
CYCLOGENESIS OVER THE NATION/S MID-SECTION SUNDAY. AS THIS SURFACE
LOW MOVES INTO THE OHIO VALLEY MONDAY...EXPECT WIDESPREAD WARM
ADVECTION AHEAD OF THIS LOW TO WORK ITS WAY INTO THE FORECAST
AREA...ALLOWING FOR TEMPERATURES TO WARM BACK INTO THE UPPER 60S
MONDAY. ACCOMPANYING THIS WARM ADVECTION WILL BE AN INCREASE WITH
POPS AS A WARM FRONTAL BOUNDARY AND ASSOCIATED ISENTROPIC UPLIFT
APPROACHES THE AREA. THERE ARE SOME DIFFERENCES BETWEEN THE LATEST
MODEL RUNS REGARDING THE LOCATION OF THE BOUNDARY WITH THE 12Z GFS
RUN KEEPING THE BOUNDARY...AND ASSOCIATED PRECIP...JUST TO OUR SOUTH
WHILE THE ECMWF/GEM MODELS BOTH BRING WARMER AIR AND WIDESPREAD
PRECIP UP INTO THE AREA. FOR NOW WILL STICK WITH BROADBRUSH CHANCE
POPS TO REFLECT THE GENERAL TREND TOWARDS UNSETTLED WEATHER WITH
MORE REFINEMENT AS THE TIMING/LOCATION OF THE FRONTAL BOUNDARY
BECOMES CLEARER.
IN SPITE OF DIFFERENCES IN THE DETAILS...MODELS ALL AGREE ON THE
DEVELOPMENT OF A FULL LATITUDE UPPER LEVEL TROUGH OVER THE EASTERN
UNITED STATES ON TUESDAY AS THE AFOREMENTIONED UPPER LOW OVER THE
UPPER MIDWEST MOVES EAST AND PHASES WITH THE CUTOFF LOW OVER QUEBEC.
THIS LARGE TROUGH WILL BE SITUATED ACROSS THE FORECAST AREA BY THE
MIDDLE OF NEXT WEEK...RESULTING IN WIDELY SCATTERED SHOWER ACTIVITY
AND A COOLING TREND BACK TO NEAR SEASONAL NORMALS.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
THE MAIN AREA OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO EXIT
TO THE EAST THROUGH 12Z. THERE IS A SECONDARY AREA OF SHOWERS WITH
EMBEDDED THUNDERSTORMS...WHICH APPEARS MUCH LESS ACTIVE THAN THE
FIRST LINE. HOWEVER...THIS MAY BRING ANOTHER TSTM TO BUF/IAG
DURING THE EARLY MORNING HOURS...WITH AN OUTSIDE CHANCE FOR TSTMS
AT OTHER TAF LOCATIONS. CHANCES FOR SHOWERS WILL DIMINISH FROM
NORTH TO SOUTH ON FRIDAY.
OUTSIDE OF SHOWERS CONDITIONS SHOULD MAINLY BE VFR. HOWEVER...ANY
CLEARING WIND SHIFT TO A PERSISTENT ONSHORE FLOW WOULD HAVE THE
POTENTIAL TO LOWER CIGS/VSBY GIVEN THE MOIST BOUNDARY LAYER.
OUTLOOK...
FRIDAY NIGHT...MVFR/VFR WITH LINGERING SHOWERS ENDING.
SATURDAY THROUGH MONDAY...VFR.
TUESDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
&&
.MARINE...
ADDED SOME FOG OVER LAKE ONTARIO FOR THIS EVENING WITH THE
COMBINATION OF WARM/MOIST AIR OVER A COLD LAKE PRODUCING SOME
REDUCTION IN VISIBILITY PER THE VISIBLE SATELLITE IMAGERY AND
WEBCAMS.
GENERALLY LIGHT TO MODEST WINDS WILL CONTINUE ACROSS THE LOWER LAKES
REGION OVER THE NEXT FEW DAYS...WITH NO WIND HEADLINES ANTICIPATED
THROUGH THE WEEKEND. THE ABOVE SAID...THERE WILL BE THE POSSIBILITY
OF SOME THUNDERSTORMS TONIGHT AND FRIDAY AS A LOW PRESSURE SYSTEM
EASES SOUTHEAST ACROSS THE REGION...SOME OF WHICH COULD PRODUCE
LOCALLY HIGHER WINDS AND WAVES.
AFTER FRIDAY...HIGH PRESSURE WILL BUILD BACK ACROSS THE REGION AND
BRING A RETURN TO FAIR WEATHER.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JJR
NEAR TERM...APFFEL/HITCHCOCK/JJR
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...APFFEL
MARINE...HITCHCOCK/JJR
AREA FORECAST DISCUSSION
NWS DENVER CO
942 AM MDT FRI MAY 4 2012
.UPDATE...CURRENT FORECAST TRENDS STILL LOOKING ON TRACK. FOG OVER
NORTHEAST CORNER HAS DISSIPATED AND STRATUS EXITED THE AREA.
AIRMASS LOOKS DRY AND STABLE...SO NO SHOWERS OR STORMS EXPECTED. ONLY
CONCERN FOR THIS AFTERNOON AND EARLY EVENING IS THE RED FLAG
CONDITIONS FOR NORTH AND MIDDLE PARKS DUE TO GUSTY WINDS AND LOW
RH. LATEST MODEL DATA CONTINUES TO SUPPORTS CRITICAL CONDITIONS
THERE. WINDS ACROSS SOUTH PARK STILL LOOKING MARGINAL AND WILL
HOLD OFF ON ISSUING A RED FLAG HILITE THERE FOR NOW. A BIT OF A
HEADS UP FOR TOMORROW...CONDITIONS ACROSS NORTH AND MIDDLE PARKS
DON`T SEEM TO CHANGE MUCH SO ANOTHER RED FLAG HILITE MAY BE
NEEDED. SOUTH PARK MAY ALSO BE INCLUDED. BUT WILL ADDRESS THIS
ISSUE LATER WHEN MORE DATA POURS IN.
&&
.AVIATION...CURRENT TAF TRENDS LOOKING REASONABLE...WILL CONTINUE
FOR THE 18Z ISSUANCE. WEAK FRONT PASSING SOUTH ACROSS PLAINS
TONIGHT COULD BRUSH AREA AIRPORTS EARLY SATURDAY MORNING. HOWEVER
LATEST DATA SUGGESTS DRAINAGE WINDS PREVAILING WHICH SHOULD KEEP
FRONT NORTH AND EAST OF AREA.
&&
.PREV DISCUSSION... /ISSUED 420 AM MDT FRI MAY 4 2012/
SHORT TERM...DRY SOUTHWEST FLOW ALOFT WILL BE OVER THE AREA
THROUGH TONIGHT WITH NO CHANCE OF PCPN. SOME DENSE FOG WILL BE
POSSIBLE OVER THE FAR NE CORNER THRU MID MORNING AND HAVE ALREADY
ISSUED AN ADVISORY. MEANWHILE MAIN CONCERN FOR THIS AFTN WILL BE
FIRE DANGER OVER THE HIGHER VALLEYS. LATEST DATA WOULD SUPPORT A
RED FLAG WARNING FOR ZNS 211 AND 213. PARK COUNTY IS A BIT MORE
IFFY DUE TO WINDS SO WILL HOLD OFF FOR NOW. HIGHS THIS AFTN WILL
BE A FEW DEGREES WARMER THAN THU IN MOST AREAS WITH 80S OVER NERN
CO.
FOR TONIGHT A CDFNT WILL MOVE INTO THE FAR NERN CORNER AFTER
MIDNIGHT WITH SOME STRATUS DEVELOPING BY 12Z.
LONG TERM...DRY AND WARM CONDITIONS ARE EXPECTED TO CONTINUE ON
SATURDAY AS MODERATE SOUTHWEST FLOW ALOFT REMAINS OVER THE STATE.
CHANGES WILL BE ON THEIR WAY SATURDAY NIGHT AND SUNDAY AS AN UPPER
TROUGH MOVES IN FROM THE NORTHWEST AND A STRONG COLD FRONT ENTERS
THE STATE FROM THE NORTH. UPSLOPE FLOW BEHIND THE FRONT WILL BRING
MUCH COOLER TEMPERATURES AND A MOISTENING AIRMASS TO THE REGION.
SUNDAY MORNING WILL BE TOO STABLE FOR ANY THUNDERSTORMS...BUT
HEATING THROUGH THE DAY ON SUNDAY COULD ALLOW AFTERNOON ACTIVITY
TO DEVELOP. COOL AND MOIST CONDITIONS WILL LAST THROUGH MONDAY AND
INTO TUESDAY MORNING AS UPPER TROUGHINESS REMAINS OVER NORTHEAST
COLORADO. FROM TUESDAY THROUGH THE REST OF THE WEEK...THE GFS AND
ECMWF SHOW WEAK UPPER RIDGING OVER COLORADO AS A CUTOFF LOW
LINGERS OVER NORTHWESTERN MEXICO. DYNAMICS AND WINDS SHOULD BE
WEAK UNDER THIS PATTERN AS WELL AS DRY. THE ECMWF IS MUCH DRIER
THAN THE GFS WHICH KEEPS BRINGING SOME MOISTURE OVER SOUTHWESTERN
COLORADO. HAVE REMOVED POPS FROM MOST OF THE FORECAST AREA FOR THE
TUESDAY THROUGH THURSDAY TIME PERIOD. TEMPERATURES WILL ALSO BE
GRADUALLY WARMING THROUGH THE WEEK AS THE UPPER RIDGING REMAINS IN
PLACE. IN SUMMARY...SUNDAY AND MONDAY WILL BE THE BEST OPPORTUNITY
FOR PRECIPITATION ACROSS THE FORECAST AREA WITH TEMPERATURES
BRIEFLY DROPPING TO COOLER THAN NORMAL. BUT THE CHANGE IN WEATHER
WILL BE SHORT LIVED AS WE WARM BACK ABOVE NORMAL BY MID-WEEK.
AVIATION...VFR THRU TONIGHT. WINDS WILL BE SSW THRU 15Z HOWEVER
AFTER THAT LATEST RUC IS SHOWING A WEAK LONGMONT ANTICYCLONE DUE
TO WNW FLOW OVER THE CHEYENNE RIDGE. THUS WINDS BY LATE MORNING MAY
BECOME LIGHT NNE AND THEN MORE ENE THRU THE AFTN HOURS. LATEST HI RES
WRF KEEPS WINDS LIGHT ELY THRU THE EARLY EVENING HOURS AND THEN
SHIFTS THEM TO THE SSW BY 06Z.
HYDROLOGY...NO TSTMS TODAY OR TONIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ211-213.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER CO
420 AM MDT FRI MAY 4 2012
.SHORT TERM...DRY SOUTHWEST FLOW ALOFT WILL BE OVER THE AREA
THROUGH TONIGHT WITH NO CHANCE OF PCPN. SOME DENSE FOG WILL BE
POSSIBLE OVER THE FAR NE CORNER THRU MID MORNING AND HAVE ALREADY
ISSUED AN ADVISORY. MEANWHILE MAIN CONCERN FOR THIS AFTN WILL BE
FIRE DANGER OVER THE HIGHER VALLEYS. LATEST DATA WOULD SUPPORT A
RED FLAG WARNING FOR ZNS 211 AND 213. PARK COUNTY IS A BIT MORE
IFFY DUE TO WINDS SO WILL HOLD OFF FOR NOW. HIGHS THIS AFTN WILL
BE A FEW DEGREES WARMER THAN THU IN MOST AREAS WITH 80S OVER NERN
CO.
FOR TONIGHT A CDFNT WILL MOVE INTO THE FAR NERN CORNER AFTER
MIDNIGHT WITH SOME STRATUS DEVELOPING BY 12Z.
.LONG TERM...DRY AND WARM CONDITIONS ARE EXPECTED TO CONTINUE ON
SATURDAY AS MODERATE SOUTHWEST FLOW ALOFT REMAINS OVER THE STATE.
CHANGES WILL BE ON THEIR WAY SATURDAY NIGHT AND SUNDAY AS AN UPPER
TROUGH MOVES IN FROM THE NORTHWEST AND A STRONG COLD FRONT ENTERS
THE STATE FROM THE NORTH. UPSLOPE FLOW BEHIND THE FRONT WILL BRING
MUCH COOLER TEMPERATURES AND A MOISTENING AIRMASS TO THE REGION.
SUNDAY MORNING WILL BE TOO STABLE FOR ANY THUNDERSTORMS...BUT
HEATING THROUGH THE DAY ON SUNDAY COULD ALLOW AFTERNOON ACTIVITY
TO DEVELOP. COOL AND MOIST CONDITIONS WILL LAST THROUGH MONDAY AND
INTO TUESDAY MORNING AS UPPER TROUGHINESS REMAINS OVER NORTHEAST
COLORADO. FROM TUESDAY THROUGH THE REST OF THE WEEK...THE GFS AND
ECMWF SHOW WEAK UPPER RIDGING OVER COLORADO AS A CUTOFF LOW
LINGERS OVER NORTHWESTERN MEXICO. DYNAMICS AND WINDS SHOULD BE
WEAK UNDER THIS PATTERN AS WELL AS DRY. THE ECMWF IS MUCH DRIER
THAN THE GFS WHICH KEEPS BRINGING SOME MOISTURE OVER SOUTHWESTERN
COLORADO. HAVE REMOVED POPS FROM MOST OF THE FORECAST AREA FOR THE
TUESDAY THROUGH THURSDAY TIME PERIOD. TEMPERATURES WILL ALSO BE
GRADUALLY WARMING THROUGH THE WEEK AS THE UPPER RIDGING REMAINS IN
PLACE. IN SUMMARY...SUNDAY AND MONDAY WILL BE THE BEST OPPORTUNITY
FOR PRECIPITATION ACROSS THE FORECAST AREA WITH TEMPERATURES
BRIEFLY DROPPING TO COOLER THAN NORMAL. BUT THE CHANGE IN WEATHER
WILL BE SHORT LIVED AS WE WARM BACK ABOVE NORMAL BY MID-WEEK.
&&
.AVIATION...VFR THRU TONIGHT. WINDS WILL BE SSW THRU 15Z HOWEVER
AFTER THAT LATEST RUC IS SHOWING A WEAK LONGMONT ANTICYCLONE DUE
TO WNW FLOW OVER THE CHEYENNE RIDGE. THUS WINDS BY LATE MORNING MAY
BECOME LIGHT NNE AND THEN MORE ENE THRU THE AFTN HOURS. LATEST HI RES
WRF KEEPS WINDS LIGHT ELY THRU THE EARLY EVENING HOURS AND THEN
SHIFTS THEM TO THE SSW BY 06Z.
&&
.HYDROLOGY...NO TSTMS TODAY OR TONIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 8 AM MDT THIS MORNING FOR COZ050-051.
RED FLAG WARNING FROM NOON TODAY TO 8 PM MDT THIS EVENING FOR
COZ211-213.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
734 AM CDT FRI MAY 4 2012
.SHORT TERM.../TODAY/
WEAK SYNOPTIC SCALE FORCING ASSOCIATED WITH ELONGATED SHORT WAVE
FROM WRN GREAT LAKES INTO TX PANHANDLE CONTINUES TO COMBINE WITH
MOISTURE CONVERGENCE ALONG 305K ISENT SURFACE TO PRODUCE SCATTERED
THUNDERSTORMS ACROSS SRN IA. ORIGINALLY THOUGHT MO MCS WOULD
INTERCEPT INFLOW KEEPING CONVERGENCE TO OUR SOUTH...HOWEVER LARGER
SCALE FORCING HAS APPARENTLY ALLOWED MORE DEVELOPMENT FARTHER
NORTH. ELEVATED CAPES UP TO 2500 J/KG AND LITTLE CINH WITH ADEQUATE
EFFECTIVE SHEAR CONTINUE TO PRODUCE SUPERCELLS WITH HEAVY RAIN
POTENTIAL. EXPECT BOTH SEVERE AND HEAVY RAIN THREATS TO DIMINISH BY
SUNRISE HOWEVER AS 305K FLOW CONTINUES TO VEER AND WEAKEN...REDUCING
CONVERGENCE.
QUESTION THEN TURNS TO REDEVELOPMENT LATER IN THE DAY. NAM AND GFS
BOTH BUILD ANOTHER ROUND OF 2500-3000 J/KG MLCAPES AND LITTLE CINH
INTO THE HEART OF IA AS WARM FRONT GRADUALLY SURGES BACK NORTHWARD
INTO THE STATE...CONNECTING TO WEAK SURFACE WAVE OVER SRN SD.
CONVERGENCE WITH THIS FEATURE WILL BE WEAK BUT HRRR AND NMM WRF TRY
TO DEVELOP ISOLATED CONVECTION DURING PEAK HEATING. NOT COMFORTABLE
GOING DRY SO HAVE GONE WITH SLIGHT CHANCES DURING THE AFTERNOON.
BETTER SVR THREAT WOULD BE OVER NRN IA WHERE 0-6KM SHEAR IS THE
HIGHEST. IF ANY STORMS DO FORM THEY WOULD AGAIN BE SLOW MOVING WITH
WEAK H85/H3 WINDS AND B2K SUPERCELL MOTION. LIGHT WINDS...VERY
SEASONALLY HIGH PWS AND DEEP WARM CLOUD DEPTHS COULD ALSO PRODUCE
ISOLATED HEAVY RAINS IF ANYTHING DOES DEVELOP.
.LONG TERM.../TONIGHT THROUGH THURSDAY/
LONG TERM FORECAST IS A CHALLENGE ESPECIALLY EARLY IN THE PERIOD
UNTIL THE SYNOPTIC FRONT MOVES THROUGH SUNDAY NIGHT INTO MONDAY.
MESOSCALE FEATURES WILL BE A MAJOR FACTOR UNTIL THEN...SO WILL
HAVE TO GIVE DUE CONSIDERATION TO THEM IN ADDITION TO SYNOPTIC
FEATURES. IN ADDITION...SEVERE WEATHER AND HEAVY RAIN WILL REMAIN
A THREAT UNTIL THE SYNOPTIC FRONT MOVES THROUGH LATE THIS
WEEKEND.
FOR TONIGHT...ANY STORMS THAT DO DEVELOP WILL HAVE THE POTENTIAL
TO BE SEVERE. IN ADDITION...THEY WOULD BE EFFICIENT RAINFALL
PRODUCERS. FORECAST SOUNDINGS INDICATE PRECIPITABLE WATER VALUES
WILL BE AS HIGH AS THE 1.5 TO 1.75 RANGE TONIGHT...WHICH WOULD BE
BETWEEN THE 99TH PERCENTILE AND THE RECORD HIGH VALUES FOR THIS
TIME OF YEAR. IN ADDITION...COMPARISON OF MEAN STORM MOTION AND
CORFIDI VECTORS INDICATE THAT ANY STORMS WHICH DO DEVELOP WILL
EITHER BE SLOW MOVERS OR WILL TRAIN. THUS HAVE ADDED MENTION OF
HEAVY RAIN IN TONIGHT/S FORECAST. WILL LEAVE THE DECISION OF A
POTENTIAL FLASH FLOOD WATCH WITH THE DAY SHIFT.
THUNDERSTORM CHANCES WILL BE LOWER DURING THE DAY ON
SATURDAY...BUT WILL RETURN AGAIN SATURDAY NIGHT. ALTHOUGH
FORECAST SOUNDINGS INDICATE LOWER PRECIPITABLE WATER VALUES THAN
THOSE EXPECTED FOR TONIGHT...HEAVY RAIN WILL AGAIN BE A
POSSIBILITY IN ADDITION TO SEVERE WEATHER. OF COURSE...MESOSCALE
FEATURES MAY HELP ENHANCE ANY THUNDERSTORM ACTIVITY.
UPPER AIR PATTERN AND SENSIBLE WEATHER UNDERGO A SIGNIFICANT
SHIFT SUNDAY NIGHT INTO MONDAY...AS THE SYNOPTIC FRONT MOVES
THROUGH AND THEN AN UPPER LEVEL LOW SHIFTS SOUTHWARD FROM CANADA
TO THE NORTHERN CONUS. OVERALL...WEATHER WILL BECOME DRIER BUT
SOME PCPN IS POSSIBLE IN ASSOCIATION WITH THE UPPER LEVEL LOW. AT
THIS TIME THE BEST CHANCES FOR PCPN WOULD BE TO OUR NORTH.
&&
.AVIATION...04/12Z
CLUSTER OF SCATTERED THUNDERSTORMS WILL CONTINUE TO AFFECT SERN IA
THIS MORNING WITH PATCHY MVFR/IFR CONDITIONS IN LOW CLOUDS...EVEN
DOWN TO LIFR IN SPOTS INCLUDING KDSM. CONDITIONS SHOULD GRADUALLY
IMPROVE LATER THIS MORNING AS CONVECTION EXITS. NEBULOUS FRONTAL
BOUNDARY ALONG IOWA MISSOURI BORDER WILL LIFT NORTHWARD BACK INTO IA
LATER TODAY AND MAY DEVELOP ADDITIONAL STORMS DURING PEAK HEATING.
CONFIDENCE IN TIMING AND LOCATION IS NOT GREAT ENOUGH TO INCLUDE AT
THE MOMENT...BUT LATE AFTERNOON AND THIS EVENING WOULD BE THE MOST
LIKELY TIMES. LATER TONIGHT SELY SURFACE FLOW BECOMES MORE ELY WITH
MODELS AND MOS GUIDANCE SUGGESTING SATURATED LOW LEVELS. THIS WILL
LIKELY LEAD TO REDUCED VISIBILITIES AND LOW CIGS WITH MOST FAVORABLE
LOCATIONS NERN HALF OF IA.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 9 AM CDT THIS MORNING FOR APPANOOSE-
DAVIS-MAHASKA-MONROE-WAPELLO.
&&
$$
SHORT TERM/AVIATION...SMALL
LONG TERM...ZOGG
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
606 AM CDT FRI MAY 4 2012
...UPDATED AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 202 AM CDT FRI MAY 4 2012
00Z 4 MAY 2012 250 HPA MAP ANALYSIS SHOWED A 115 KT JET EXTENDING FROM
NORTHERN CALIFORNIA AND ACROSS THE IDAHO TREASURE VALLEY. ANOTHER 115
KT JET WAS LOCATED ACROSS NORTHEASTERN ONTARIO. A WEAKER 75 KT SUBTROPICAL
JET WAS LOCATED ACROSS CHIHUAHUA AND ACROSS SOUTHWEST TEXAS. AT 500
HPA, SEVERAL SHORTWAVE TROUGHS WERE NOTED ACROSS THE CONUS. ONE OF THESE
WEAK IMPULSES TRIGGERED CONVECTION ACROSS SOUTHEASTERN COLORADO EARLIER
IN THE DAY. AT 700 HPA, VERY LITTLE CHANGE IN THE THERMODYNAMIC PROFILE
WAS NOTED ACROSS THE CENTRAL AND SOUTHERN PLAINS WITH VERY WARM TEMPERATURES
OF 10 TO 13 DEG C EXTENDING FROM THE TEXAS PANHANDLE AND ACROSS SOUTHWEST
KANSAS. A SIMILAR WARM PATTERN AT 850 HPA WITH TEMPERATURES IN THE 20
TO 29 DEG C PREVAILED ACROSS THE HIGH PLAINS. AT THE SURFACE, SIGNIFICANT
GULF OF MEXICO MOISTURE AS MARKED BY DEWPOINTS IN THE UPPER 60S TO LOWER
70S DEG F WAS OBSERVED EAST OF A DRYLINE FROM TEXAS TO KANSAS.
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 202 AM CDT FRI MAY 4 2012
THIS MORNING:
AROUND MIDNIGHT, CONVECTION ERUPTED ACROSS SOUTH CENTRAL KANSAS ON THE
NOSE OF A 50 KT 850 HPA JET. THE ONLY MODELS THAT CAPTURED THIS CORRECTLY
WAS THE GFS AND WRF-NMM. THIS CLUSTER HAS ALREADY MOVED OUT OF THE REGION
BUT DID MANAGE TO PUT DOWN SOME SEVERE HAIL.
THE NEXT MORNING CONCERN IS MOISTURE POOLING NORTH OF A SURFACE LOW.
THIS WILL CREATE SOME STRATUS FROM DODGE CITY TO HAYS THIS MORNING.
RELATIVE HUMIDITY PROGS AND OUTPUT FROM THE RAP SHOW THAT THE MOST LIKELY
AREA FOR LOWERED VISIBILITIES AND ENHANCED CLOUD COVER IS ACROSS THE
INTERSTATE 70 CORRIDOR. THE LOW LEVEL CLOUDS SHOULD START TO ERODE BY
MID MORNING.
TODAY:
TODAY WILL BE HOT WITH TEMPERATURES IN THE 90S DEG F. THIS IS A GOOD
20 DEGREES ABOVE NORMAL. FORECAST SOUNDINGS SHOW THE ATMOSPHERE BECOMING
DEEPLY MIXED TO ABOUT 500 HPA.FORECAST SOUNDINGS ARE ALSO FAIRLY DRY
SO EXPECTING FULL INSOLATION AFTER THE AFOREMENTIONED LOW CLOUDS DISSIPATE.
NO PRECIPITATION IS EXPECTED TODAY AS 500 HPA GEOPOTENTIAL HEIGHTS INCREASE
THROUGH THE DAY WITH SUBSIDENCE CONTINUING THROUGH THE ATMOSPHERIC COLUMN
IN RESPONSE TO MID AND LOW LEVEL RIDGING.
TONIGHT:
TRANQUIL WEATHER WILL CONTINUE THROUGH THE OVERNIGHT PERIOD. WEAK LEE
SURFACING TROUGHING ACROSS FAR EASTERN COLORADO WILL KEEP SOUTHERLY
WINDS IN THE FORECAST. SURFACE DEWPOINTS WILL MIX DOWN TO THE 30S DEG
F WEST TO AROUND 60 DEG F EAST THROUGH THE OVERNIGHT PERIOD. AS A RESULT,
OVERNIGHT LOWS WILL BE SLIGHTLY COOLER THAN COMPARED TO PREVIOUS NIGHTS
WITH 50S DEG F EXPECT ACROSS SW KANSAS AND LOW 60S DEG F EXPECTED ACROSS
SOUTH CENTRAL KANSAS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 315 AM CDT FRI MAY 4 2012
MODELS THIS MORNING REMAIN IN DECENT AGREEMENT WITH CONVECTION
DEVELOPING LATE SATURDAY NEAR THE RIGHT EXIT REGION OF AN UPPER
LEVEL JET THAT WILL BE LOCATED NEAR EASTERN WYOMING/NORTHEAST COLORADO.
THIS CONVECTION IS THEN FORECAST TO SPREAD EAST INTO NEBRASKA AND
PORTIONS OF NORTHERN KANSAS DURING THE OVERNIGHT PERIOD AS THIS
JET STREAK MOVES NORTHEAST INTO THE NORTHERN PLAINS. A COLD FRONT
WILL SURGE SOUTH ACROSS WESTERN KANSAS LATE SATURDAY NIGHT AND BY
EARLY SUNDAY MORNING THIS FRONT WILL EXTEND FROM SOUTH CENTRAL
KANSAS INTO THE PANHANDLE OF TEXAS. BEHIND THIS FRONT GUSTY NORTH
WINDS ARE STILL EXPECTED BASED ON THE TIGHT PRESSURE GRADIENT AND
925-850MB WINDS. GIVEN THE WINDS FORECAST IN THE BOUNDARY LEVEL
AND AT THE 850MB LEVEL SUNDAY WOULD NOT BE SURPRISED TO SEE WIND
SPEEDS REACHING WIND ADVISORY CRITERIA. AS A RESULT DID INCREASE
WINDS EARLY SUNDAY BEHIND THIS FRONT TO JUST BELOW 26KNOTS. 850MB
MIX DOWN TEMPERATURES FROM THE GFS AND ECMWF AT 18Z SUNDAY AND 00Z
MONDAY CONTINUE TO SUPPORT THE PREVIOUS TRENDS OF LOWERING
TEMPERATURES SUNDAY AFTERNOON. PRECIPITATION CHANCES WITH THE
FRONT STILL APPEARS SMALL WITH THE POSSIBLE EXCEPTION BEING
NORTHEAST/EAST OF DODGE CITY BASED ON LOW LEVEL MOISTURE AND
850-700MB FORCING BEING PRESENT EARLY SUNDAY.
SUNDAY NIGHT AND MONDAY A COOL DOME OF HIGH PRESSURE WILL SETTLE
INTO WESTERN KANSAS AS THIS COLD FRONT CONTINUES TO TRACK SOUTH
INTO CENTRAL/SOUTHERN TEXAS. 850MB TEMPERATURE TRENDS FROM BOTH
THE GFS AND ECMWF CONTINUES TO SUPPORT HIGHS ON MONDAY RANGING
FROM THE UPPER 60S TO LOWER 70S. THE CENTER OF THIS SURFACE HIGH
IS FORECAST TO CROSS WESTERN KANSAS MONDAY NIGHT, HOWEVER CLOUD
COVER WILL BE ON THE INCREASE AS ANOTHER UPPER LEVEL TROUGH BEGINS
TO APPROACH THE AREA AND MID LEVEL MOISTURE AND WARM AIR ADVECTION
DEVELOPS ACROSS EASTERN COLORADO/WESTERN KANSAS. IN ADDITION TO
INCREASING CLOUDS THERE MAY ALSO BE A CHANCE FOR SOME
PRECIPITATION LATE MONDAY THROUGH TUESDAY AHEAD OF THIS UPPER
TROUGH SO WILL KEEP A CHANCE OF PRECIPITATION GOING UNTIL THIS
NEXT SYSTEM FINALLY MOVES EAST OF WESTERN KANSAS. TEMPERATURES ARE
EXPECTED TO BE THE NEAR SEASONAL NORMALS THROUGH MID WEEK AS A
REINFORCEMENT OF COOLER AIR BRIEFLY RETURNS TO WESTERN KANSAS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 602 AM CDT FRI MAY 4 2012
WEAK UPSLOPE FLOW PERSISTS ACROSS NORTH CENTRAL AND MUCH OF
SOUTHWEST KANSAS EARLY THIS MORNING. HRRR EVEN SUGGESTS AREAS OF
DENSE FOG WILL STILL BE LIKELY FOR A FEW HOURS AT HAYS, HOWEVER
06Z NAM BUFR SOUNDINGS INDICATING ONLY A SHALLOW LAYER MOISTURE
WILL BE PRESENT IN THIS AREA THROUGH 14Z. GIVEN LATEST SATELLITE
TRENDS AND WEAK UPSLOPE FLOW WILL CONTINUE TO TREND TOWARDS A
BRIEF PERIOD OF IFR CONDITIONS AT HAYS WHILE ONLY MVFR VSBYS AT
DDC AND GCK UNTIL 14Z. AFTER 14Z VFR CONDITIONS CAN EXPECT AT ALL
TAF SITES. LIGHT WINDS WILL BECOME SOUTH/SOUTHWEST AND INCREASE TO
NEAR 10KTS BY MID DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 92 58 95 61 / 0 0 0 10
GCK 93 55 95 59 / 0 0 0 10
EHA 94 57 93 59 / 0 0 0 10
LBL 95 56 96 59 / 0 0 0 10
HYS 91 59 92 62 / 0 0 0 20
P28 95 63 96 66 / 0 0 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR KSZ030-031-
043>046.
&&
$$
SYNOPSIS...SUGDEN
SHORT TERM...SUGDEN
LONG TERM...BURGERT
AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
816 AM CDT FRI MAY 4 2012
.UPDATE...EXTENDED THE DENSE FOG ADVISORY UNTIL 10 AM WITH THE
MAJORITY OF AUTOMATED STATIONS ACROSS THE CWA REMAINING AT/BELOW
ONE QUARTER OF A MILE. OTHERWISE ONLY MINOR TWEAKS MADE
&&
.PREV DISCUSSION... /ISSUED 356 AM CDT FRI MAY 4 2012/
SHORT TERM...TODAY THROUGH SUNDAY NIGHT. AREAS OF FOG DEVELOPED
EARLY THIS MORNING IN PRESENCE OF LLVL MOISTURE AND NEARLY CALM OR
LIGHT EASTERLY WINDS. RUC13 SEEMS TO BE HANDLING THE VSBYS THE BEST
AND SUGGESTS PRETTY MUCH OUR ENTIRE CWA MAY BE UNDER INFLUENCE OF
DENSE FOG BY MORNING AND HAVE ISSUED DENSE FOG ADV UNTIL 8 AM FOR
ALL BUT OUR FAR NORTHERN COUNTIES WHERE TEMP/DP SPREAD IS
CURRENTLY GREATER...AND OUR FAR EASTERN CWA WHERE HIGH CLOUD COVER
FM CONVECTION TO OUR SE MAY HOLD UP VSBYS. WILL CONTINUE TO
MONITOR TRENDS EARLY THIS MORNING AS TO WHETHER HEADLINE NEEDS TO
BE EXPANDED OR NOT.
LOOKING FOR FOG TO BURN OFF AFTER DAYBREAK WITH DAYTIME
HEATING...THEN MUCH OF THE DAY IS LOOKING DRY. PATTERN ALOFT
FEATURED SOUTHWESTERLY FLOW WITH MID/UPPER TROUGH ORIENTED FM
ALBERTA INTO THE NORTHERN ROCKIES. JET STREAK NOSES INTO THE NC
ROCKIES TODAY WHILE A SERIES OF SUBTLE SHORTWAVE LIFT FM BASE OF
TROUGH. AT THE SURFACE WARM FRONT LIFTS INTO NC NEB THIS AFTERNOON
AND CONVERGENCE ALONG FRONT AND ENERGY ASSOCIATED WITH WAVES IS
EXPECTED TO INITIATE CONVECTION IN VCNTY OF FRONT. SREF INDICATES
AN AXIS OF INSTABILITY MUCAPES OF 4000 J/KG ACROSS EASTERN NEB/KS
WITH EFFECTIVE SHEAR AROUND 30KTS IN OUR CWA....INCREASING TO NEAR
50 KTS NEAR THE FRONTAL BOUNDARY JUST TO OUR NORTH. INITIATION
LOOKS TO BE JUST TO OUR NORTH ALONG THE FRONT FOR MAIN FOCUS WITH
ACTIVITY POTENTIALLY REACHING OUR NORTHERN ZONES TONIGHT. SOME
QUESTION AS TO WHETHER ACTIVITY MAY FIRE TO THE WEST NEAR THE DRY
LINE OR PERHAPS A DIFFERENTIAL HEATING BOUNDARY AS OCCURRED
YESTERDAY. FOR NOW WILL MAINTAIN MAIN FOCUS ALONG THE WARM FRONT
FOR TONIGHT...WITH SEVERE STORMS POSSIBLE. ALSO FOR TONIGHT...LLVL
FLOW REMAINS FM A LIGHT EASTERLY DIRECTION AS BOUNDARY SAGS SOUTH.
LOOKING AT POTENTIAL FOR FOG DEVELOPMENT AGAIN OVERNIGHT.
ON SATURDAY...WARM FRONT LIFTS NORTH IN AFTERNOON THEN COOL FRONT
PUSHES SOUTH SATURDAY NIGHT. LOOKING AT FAIRLY DECENT CHCS FOR
CONVECTION SATURDAY NIGHT AS THE STRONGER FRONT MOVES THROUGH AS
UPPER TROUGH CROSSES THE DAKOTAS. SEVERE STORMS ARE PROBABLE AGAIN
IN PRESENCE OF HIGH INSTABILITY AHEAD OF APPROACHING BOUNDARY AND
INCREASING SHEAR AS FRONT APPROACHES. COLD FRONT REACHES ALL BUT OUR
FAR SOUTHEAST CWA BY SUNDAY MORNING...AND HAVE LINGERED SOME
THUNDER INTO SUNDAY IN THIS AREA...WITH JUST RAIN SHOWERS FARTHER
NORTH AS INSTABILITY DIMINISHES.
COOLER...BREEZY/WINDY CONDITIONS SETTLE IN ON SUNDAY BEHIND THE
BOUNDARY WITH PCPN CHCS DECREASING DURING THE DAY. DRY WEATHER IS
FORECAST SUNDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY.
BY MONDAY...AN UPPER LEVEL RIDGE ACROSS THE EASTERN HALF OF THE
CONUS WILL BEGIN TO BREAK DOWN AS AN UPPER LEVEL TROUGH PUSHES
ACROSS THE CENTRAL CONUS. RIDGING WILL PUSH ACROSS THE NORTHWEST
COAST BEHIND THE TROUGH...WHILE A CLOSED UPPER LOW WILL PUSH ACROSS
THE SOUTHEAST ASSOCIATED WITH THE BASE OF THE TROUGH. AT THE SURFACE
LOW PRESSURE IS EXPECTED TO SHIFT ACROSS SOUTHERN CANADA WHILE HIGH
PRESSURE REMAINS CENTERED ACROSS THE ROCKIES.
THE UPPER LEVEL TROUGH IS EXPECTED TO DIVE SOUTHEAST ACROSS THE OHIO
RIVER VALLEY IN THE LONG TERM PERIOD. WITH THE SURFACE LOW FOLLOWING
SUIT...HIGH PRESSURE FROM CANADA WILL SLIDE SOUTHWARD INTO THE
CENTRAL PLAINS. COOLER 850 MB TEMPERATURES WILL ALSO SHIFT
SOUTHWARD...INDICATING COOLER HIGH TEMPERATURES IN THE LONG TERM
PERIOD. HOWEVER...850 MB TEMPERATURES STILL REMAIN NEAR 10 TO 13
DEGREES CELSIUS...SUGGESTING UPPER 60S TO LOWER 70S FOR HIGHS.
AT THIS TIME...THERE IS SOME DISCREPANCY AMONG MODELS REGARDING
PRECIPITATION CHANCES IN THE LONG TERM PERIOD. THE GFS REMAINS DRY
THROUGHOUT THE ENTIRE PERIOD...WHILE THE ECMWF TRIES TO GENERATE
SLIGHT POPS ACROSS THE PLAINS SPECIFICALLY TUESDAY. THE ECMWF TRIES
TO GENERATE A FEW SCATTERED POPS ACROSS THE FORECAST AREA...AS
COOLER AIR SLIDES SOUTH ALONG THE BACKSIDE OF THE TROUGH. ASSOCIATED
WITH THE LOCATION OF THE RIGHT ENTRANCE REGION OF UPPER LEVEL
JET...ENOUGH LIFT COULD BE POSSIBLE DURING THE AFTERNOON ON TUESDAY.
HOWEVER...BOTH MODELS SUGGEST DEWPOINTS IN THE 35 TO 40 DEGREE
RANGE. AT THIS POINT...DECIDED TO KEEP THE LONG TERM DRY UNTIL
MODELS CAN COME INTO BETTER AGREEMENT ON MOISTURE POTENTIAL AND
LOCATION OF THE UPPER LEVEL JET.
AVIATION...KGRI TAF UPDATE. FOG CONTINUES TO EXPAND ACROSS THE
FORECAST AREA. VISIBILITY RESTRICTIONS ARE EXPECTED TO FLUCTUATE
BETWEEN ONE QUARTER MILE AND 1 MILE AT TIMES. WITH LIGHT AND
VARIABLE WINDS AND AMPLE MOISTURE IN THE AREA...FOG MAY BE SLOW TO
DISSIPATE UNTIL SUNRISE THIS MORNING.
PREV DISCUSSION... /ISSUED 1241 AM CDT FRI MAY 4 2012/
AVIATION...06Z KGRI TAF. AS A SURFACE TROUGH PASSES THROUGH THE
REGION OVERNIGHT TONIGHT...WINDS WILL LIKELY REMAIN LIGHT AND
VARIABLE...TO EVEN CALM AT TIMES. AS A RESULT...COMBINED WITH
AMPLE MOISTURE IN THE REGION...FOG DEVELOPMENT WILL REMAIN
POSSIBLE ACROSS THE TAF SITE. FOG THAT DEVELOPS WILL LIKELY BE
PATCHY IN NATURE. NEIGHBORING SITES HAVE HAS EXPERIENCED
VISIBILITY REDUCTIONS FROM 5 SM TO EVEN A QUARTER OF A MILE IN
SOME AREAS. AT THIS TIME...DECIDED TO LEAVE MENTION OF AT LEAST
IFR VISIBILITIES AND CEILINGS IN THE TEMPO GROUP...AS MODEL
SOUNDINGS INDICATE FOG COULD EASILY REACH THE TAF SITE. BESIDES
FOG POTENTIAL THIS MORNING...CLOUD BASES SHOULD REMAIN FAIRLY HIGH
WITH THE POSSIBILITY FOR CUMULUS DEVELOPMENT THIS AFTERNOON AS
TEMPERATURES CLIMB WELL INTO THE 80S. THERE REMAINS THE
POSSIBILITY FOR THUNDERSTORMS DURING THE EVENING AND OVERNIGHT
HOURS TONIGHT...BUT EXPECT THEM TO BE SCATTERED IN NATURE SO WILL
LEAVE OUT OF THE TAF FOR NOW.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NEZ041-
046>049-060>064-072>077-082>087.
KS...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR KSZ005-006-
017-018.
&&
$$
UPDATE...ADO
AREA FORECAST DISCUSSION
NWS DENVER CO
1142 AM MDT FRI MAY 4 2012
.AVIATION...DELAYED THE SHIFT TO THE NORTHWEST AT APA AND DEN AS
ANTICYCLONE A BIT SLOW TO DEVELOP. STILL THINKING THIS WILL
OCCUR BASED ON CURRENT UPPER LEVEL WINDS AND POTENTIAL FLOW OFF
CHEYENNE RIDGE.
&&
.PREV DISCUSSION... /ISSUED 942 AM MDT FRI MAY 4 2012/
UPDATE...CURRENT FORECAST TRENDS STILL LOOKING ON TRACK. FOG OVER
NORTHEAST CORNER HAS DISSIPATED AND STRATUS EXITED THE AREA.
AIRMASS LOOKS DRY AND STABLE...SO NO SHOWERS OR STORMS EXPECTED. ONLY
CONCERN FOR THIS AFTERNOON AND EARLY EVENING IS THE RED FLAG
CONDITIONS FOR NORTH AND MIDDLE PARKS DUE TO GUSTY WINDS AND LOW
RH. LATEST MODEL DATA CONTINUES TO SUPPORTS CRITICAL CONDITIONS
THERE. WINDS ACROSS SOUTH PARK STILL LOOKING MARGINAL AND WILL
HOLD OFF ON ISSUING A RED FLAG HILITE THERE FOR NOW. A BIT OF A
HEADS UP FOR TOMORROW...CONDITIONS ACROSS NORTH AND MIDDLE PARKS
DON`T SEEM TO CHANGE MUCH SO ANOTHER RED FLAG HILITE MAY BE
NEEDED. SOUTH PARK MAY ALSO BE INCLUDED. BUT WILL ADDRESS THIS
ISSUE LATER WHEN MORE DATA POURS IN.
AVIATION...CURRENT TAF TRENDS LOOKING REASONABLE...WILL CONTINUE
FOR THE 18Z ISSUANCE. WEAK FRONT PASSING SOUTH ACROSS PLAINS
TONIGHT COULD BRUSH AREA AIRPORTS EARLY SATURDAY MORNING. HOWEVER
LATEST DATA SUGGESTS DRAINAGE WINDS PREVAILING WHICH SHOULD KEEP
FRONT NORTH AND EAST OF AREA.
PREV DISCUSSION... /ISSUED 420 AM MDT FRI MAY 4 2012/
SHORT TERM...DRY SOUTHWEST FLOW ALOFT WILL BE OVER THE AREA
THROUGH TONIGHT WITH NO CHANCE OF PCPN. SOME DENSE FOG WILL BE
POSSIBLE OVER THE FAR NE CORNER THRU MID MORNING AND HAVE ALREADY
ISSUED AN ADVISORY. MEANWHILE MAIN CONCERN FOR THIS AFTN WILL BE
FIRE DANGER OVER THE HIGHER VALLEYS. LATEST DATA WOULD SUPPORT A
RED FLAG WARNING FOR ZNS 211 AND 213. PARK COUNTY IS A BIT MORE
IFFY DUE TO WINDS SO WILL HOLD OFF FOR NOW. HIGHS THIS AFTN WILL
BE A FEW DEGREES WARMER THAN THU IN MOST AREAS WITH 80S OVER NERN
CO.
FOR TONIGHT A CDFNT WILL MOVE INTO THE FAR NERN CORNER AFTER
MIDNIGHT WITH SOME STRATUS DEVELOPING BY 12Z.
LONG TERM...DRY AND WARM CONDITIONS ARE EXPECTED TO CONTINUE ON
SATURDAY AS MODERATE SOUTHWEST FLOW ALOFT REMAINS OVER THE STATE.
CHANGES WILL BE ON THEIR WAY SATURDAY NIGHT AND SUNDAY AS AN UPPER
TROUGH MOVES IN FROM THE NORTHWEST AND A STRONG COLD FRONT ENTERS
THE STATE FROM THE NORTH. UPSLOPE FLOW BEHIND THE FRONT WILL BRING
MUCH COOLER TEMPERATURES AND A MOISTENING AIRMASS TO THE REGION.
SUNDAY MORNING WILL BE TOO STABLE FOR ANY THUNDERSTORMS...BUT
HEATING THROUGH THE DAY ON SUNDAY COULD ALLOW AFTERNOON ACTIVITY
TO DEVELOP. COOL AND MOIST CONDITIONS WILL LAST THROUGH MONDAY AND
INTO TUESDAY MORNING AS UPPER TROUGHINESS REMAINS OVER NORTHEAST
COLORADO. FROM TUESDAY THROUGH THE REST OF THE WEEK...THE GFS AND
ECMWF SHOW WEAK UPPER RIDGING OVER COLORADO AS A CUTOFF LOW
LINGERS OVER NORTHWESTERN MEXICO. DYNAMICS AND WINDS SHOULD BE
WEAK UNDER THIS PATTERN AS WELL AS DRY. THE ECMWF IS MUCH DRIER
THAN THE GFS WHICH KEEPS BRINGING SOME MOISTURE OVER SOUTHWESTERN
COLORADO. HAVE REMOVED POPS FROM MOST OF THE FORECAST AREA FOR THE
TUESDAY THROUGH THURSDAY TIME PERIOD. TEMPERATURES WILL ALSO BE
GRADUALLY WARMING THROUGH THE WEEK AS THE UPPER RIDGING REMAINS IN
PLACE. IN SUMMARY...SUNDAY AND MONDAY WILL BE THE BEST OPPORTUNITY
FOR PRECIPITATION ACROSS THE FORECAST AREA WITH TEMPERATURES
BRIEFLY DROPPING TO COOLER THAN NORMAL. BUT THE CHANGE IN WEATHER
WILL BE SHORT LIVED AS WE WARM BACK ABOVE NORMAL BY MID-WEEK.
AVIATION...VFR THRU TONIGHT. WINDS WILL BE SSW THRU 15Z HOWEVER
AFTER THAT LATEST RUC IS SHOWING A WEAK LONGMONT ANTICYCLONE DUE
TO WNW FLOW OVER THE CHEYENNE RIDGE. THUS WINDS BY LATE MORNING MAY
BECOME LIGHT NNE AND THEN MORE ENE THRU THE AFTN HOURS. LATEST HI RES
WRF KEEPS WINDS LIGHT ELY THRU THE EARLY EVENING HOURS AND THEN
SHIFTS THEM TO THE SSW BY 06Z.
HYDROLOGY...NO TSTMS TODAY OR TONIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ211-213.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
305 PM CDT FRI MAY 4 2012
.DISCUSSION...
259 PM CDT
THE MAIN CONCERNS OVER THE COMING DAYS WILL BE THE LOW CHANCES
THUNDERSTORMS ACROSS THE SOUTHWESTERN PORTION OF THE CWA
TONIGHT...AND THEN THE CHANCES FOR THUNDERSTORMS SUNDAY AFTERNOON.
FOR TONIGHT...
THE LATEST SURFACE AND OBSERVED TRENDS SHOW THAT A COOL FRONT LAY
DRAPED ACROSS MUCH OF THE CWA. AS OF THE EARLY AFTERNOON HOURS THE
BOUNDARY STRETCHES FROM KVPZ TO JUST NORTH OF KJOT....THROUGH
NORTHERN DEKALB COUNTY AND INTO WESTERN WINNEBAGO COUNTY. BEHIND
THIS FEATURE WINDS BECAME NORTHERLY TO NORTHEASTERLY...PULLING IN
THE COLD MARINE AIRMASS INTO THE LAND. TEMPS ACROSS CHICAGO PEAKED
THIS MORNING AND HAVE SINCE FALLEN THROUGH THE DAY. TO THROW
INSULT TO INJURY FOR COASTAL LOCATIONS THIS MORNING...THE CHILLY
AIRMASS COLLIDED WITH THE WARM AND HUMID AIRMASS THIS
MORNING...ALLOWING FOG...SOMETIMES THICK AT TIMES TO DEVELOP AND
MEANDER INLAND. GENERALLY SKIES HAVE CLEARED AS OF THIS
AFTERNOON...BUT SOME PATCHY AREAS PERSIST THIS AFTERNOON.
THE SURFACE BOUNDARY IS CLEARLY DENOTED ON VISIBLE IMAGERY THIS
AFTERNOON...AS SURFACE CONVERGENCE IS ALLOWING SOME CU TO POP.
DESPITE THE WARM TEMPERATURES AND HIGH DEWPOINTS PERSISTING...THE
OVERALL ATMOSPHERE IS RATHER WORKED OVER FROM LAST NIGHT AND
OBJECTIVE SPC RAP ANALYSIS CONTINUES TO HIGHLIGHT PERSISTENT CIN
IN PLACE. THE HIGHEST AXIS OF INSTABILITY IS WELL TO THE SOUTH AND
WEST THIS AFTERNOON...AND THAT IS WHERE THE HIGHEST LIKELIHOOD OF
THUNDERSTORM ACTIVITY WILL REMAIN. MODIFIED SOUNDINGS FROM
DAVENPORT SHOW THAT THERE IS MODERATE ELEVATED CAPE /ON THE ORDER
OF 1000 TO 1500 J-KG/. COUPLED WITH THE CONTINUED HIGH PWAT
AIRMASS AND SOME WEAK SURFACE CONVERGENCE ALONG THE
BOUNDARY...WOULDNT BE SURPRISED AT SEEING SOME SHOWERS DEVELOP AND
PERHAPS A CLAP OF THUNDER LATER THIS AFTERNOON AND INTO THE
EVENING HOURS. ONE BIG LACKING INGREDIENT THIS AFTERNOON IS SHEAR
ACROSS OUR AREA. THE BETTER OF THE SHEAR IS WELL TO OUR SOUTH AS A
THE REMNANTS OF A SH/WV IS SHOOTING ACROSS SOUTHERN ILLINOIS AND
SHOWERS AND SOME STRONG STORMS ARE SHOOTING EAST OF ST LOUIS TO
EFFINGHAM. THE SECOND WAVE IS LIFTING THROUGH THE DAKOTAS...AND
WILL MOVE INTO MINNESOTA AND EVENTUALLY NORTHERN
WISCONSIN...LEAVING OUR AREA IN THE VOID OF ANY ORGANIZED
CONVECTION SUPPORTING SHEAR. SO...WHATEVER DOES DECIDE TO POP THIS
AFTERNOON SHOULD GO UP AND COME DOWN IN A QUICK FASHION. WITH THE
HIGH PWATS /ON THE ORDER OF 1.3 TO 1.6 INCHES/ THROUGH THE
COLUMN...ANY OF THESE SHOWERS WILL QUICKLY DROP A GOOD AMOUNT OF
RAIN...BUT OVER A CONFINED AREA. HIGH RESOLUTION GUIDANCE IS
PRETTY CONSISTENT WITH KEEPING THE ACTIVITY FOR OUR AREA GENERALLY
FROM A ROCKFORD TO MENDOTA TO KANKAKEE CORRIDOR. THOUGH THE RAP IS
OVERDONE ACROSS THE SOUTHERN COUNTIES AS OF 20Z...AND THE HRRR IS
TRYING TO SHOW SOME ACTIVITY BEGINNING TO BUBBLE AROUND 02Z.
PRESENT CU FIELD LOOKS ANEMIC...AND GENERALLY THE REST OF THE
AFTERNOON SHOULD REMAIN CALM.
HIGH TEMPERATURES WILL RANGE GREATLY FROM NORTHEAST TO SOUTHWEST
THIS WEEKEND. THE FRONTAL BOUNDARY IS NOT EXPECTED TO MOVE MUCH FROM
ITS PRESENT LOCATION...RATHER MEANDER SLIGHTLY AND WASH OUT. AREAS
NORTH OF THIS WILL REMAIN COLDER WITH A COOL NORTHEAST COMPONENT TO
THE WINDS...WHILE AREAS SOUTH WILL GENERALLY STAY WARMER. AN UPPER
LEVEL RIDGE WILL THEN SWING ACROSS THE AREA AND GUIDANCE STILL
INDICATES A NICE LITTLE RIDGE ROLLER MOVING THROUGH AND BRINGING THE
BETTER CHANCES SHOWERS AND THUNDERSTORMS TO THE REGION OVERNIGHT ON
SUNDAY. PWATS WILL STILL BE FLIRTING WITH THE HIGH SIDE THROUGH
THIS TIME...AND THE CHANCES FOR HEAVY RAINFALL WILL PERSIST
THROUGH THAT EVENT. AS THE RIDGE SLIDES EAST AND A TROUGH MOVES
THROUGH...THE AREA WILL GENERALLY FALL BACK INTO A COOLER
NORTHWESTERLY FLOW REGIME KEEPING DAYTIME HIGHS CLOSER TO SEASONAL
WITH OFF AND ON CHANCES FOR SHOWERS THROUGH THE WEEK.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* NORTHEAST WINDS THROUGH THIS AFTERNOON.
* IFR CIGS LIKELY RETURNING LATE TONIGHT.
* POSSIBLY LOWERING VISBYS TONIGHT...ESPECIALLY IF STRATUS
DOES NOT MATERIALIZE.
* SMALL CHANCE FOR SHRA/TSRA WELL WEST AND SOUTH OF THE AIRFIELD
THIS AFTERNOON...THEN A CHANCE AT THE AIRFIELD OVERNIGHT INTO
SATURDAY MORNING.
//DISCUSSION...UPDATED 18Z...
A COOL FRONT HAD PUSHED THROUGH THE CHICAGO AREA TERMINALS EARLY
THIS MORNING...TURNING WINDS OFF OF LAKE MICHIGAN. THESE WILL
CONTINUE THROUGH TONIGHT...OFFERING THE POTENTIAL FOR THE MARINE
LAYER TO CONTINUE TO HAVE INFLUENCE. WHILE CURRENT IFR CIGS AT ORD
WILL VERY LIKELY SCATTER THIS AFTERNOON...THE RETURN OF MVFR/IFR
CIGS AND POTENTIALLY VISBYS IS CERTAINLY WITHIN REASON FOR
TONIGHT. THE NORTHERN TERMINALS OF ORD...DPA...AND RFD ARE MOST
FAVORED TO SEE THE LOWEST CONDITIONS BASED ON MORE OF A TRAJECTORY
FROM ACROSS THE LAKE.
ISOLATED SHRA/TSRA MAY DEVELOP THROUGH 23Z TO THE WEST AND SOUTH
OF THE AIRFIELD ALONG THE OLD FRONTAL BOUNDARY. LATER TONIGHT INTO
SATURDAY MORNING...SCATTERED SHOWERS ARE POSSIBLE ACROSS NORTHERN
ILLINOIS AS AN UPPER LEVEL DISTURBANCE MOVES EAST ACROSS MN AND
WI. THE CONFIDENCE IN THIS REACHING AS FAR SOUTH AS NORTHERN IL IS
LOW AT THIS TIME.
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN NORTHEAST WINDS THIS AFTERNOON...THOUGH THEY
WILL LIKELY VARY AT TIMES BETWEEN 010 AND 080. MEDIUM CONFIDENCE
THAT THESE WILL AT LEAST BE 10 KT FOR THE BETTER PART OF THE
AFTERNOON.
* MEDIUM CONFIDENCE ON AT LEAST 1500 FT AND LOWER CIGS RETURNING
TONIGHT. LOW CONFIDENCE ON DURATION AND MAGNITUDE OF THE
CIGS/VISBYS TONIGHT.
* HIGH CONFIDENCE THAT ANY SHRA/TSRA THE REST OF THIS AFTERNOON
WILL REMAIN WEST AND SOUTH OF THE AIRFIELD. LOW CONFIDENCE ON
ANY SHOWERS LATE TONIGHT.
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT THROUGH THURSDAY...GENERALLY VFR BUT PERIODIC
CHANCES FOR SHRA/TSRA. THE BEST CHANCE APPEARS TO BE SUNDAY NIGHT
AND MONDAY. DRY WEATHER IS POSSIBLE THURSDAY.
MTF
&&
.MARINE...
229 PM CDT
A COLD FRONT HAS MOVED ACROSS LAKE MICHIGAN TODAY WITH NORTHERLY
WINDS SETTING UP BEHIND THE FRONT. THE FRONTAL BOUNDARY IS FORECAST
TO STALL ACROSS CENTRAL ILLINOIS THIS EVENING WHILE HIGH PRESSURE
BUILDS ACROSS ONTARIO...THEN EVENTUALLY EAST INTO QUEBEC LATE
SATURDAY INTO SUNDAY. NORTHERLY WINDS WILL GRADUALLY VEER TO THE
NORTHEAST AND EAST AS THE HIGH TRANSLATES EAST. ON SUNDAY...THE
FRONTAL BOUNDARY WILL WAVE NORTHWARD WITH WINDS BECOMING
SOUTHEASTERLY...THEN A COLD FRONT SWEEPS ACROSS THE LAKE ON MONDAY
ALLOWING NORTHWEST/NORTH WINDS TO OVERSPREAD THE LAKE. ALL IN
ALL...NOT LOOKING AT ANY HIGH IMPACT WIND SITUATIONS THROUGH THE
FIRST HALF OF NEXT WEEK...WITH THE STRONGEST WINDS EXPECTED OVER THE
NEXT 48 HRS OR SO IN THE 15 TO 25 KT RANGE.
ANOTHER CONCERN FOR TODAY IS THE FOG OVER THE OPEN WATERS. LATEST
VISIBLE SATELLITE IMAGERY STILL PARTLY BLOCKED BY HIGHER
CLOUDS...BUT LOOKING THROUGH THE GAPS IT DOES APPEAR THAT THERE IS
STILL AN EXPANSIVE AREA OF FOG OVER SOUTHERN LAKE MICHIGAN. DRIER
AIR WILL CONTINUE TO ERODE THIS AREA FROM THE NORTH...BUT IN THE
MEANTIME WILL EXTEND THE DENSE FOG ADVISORY THROUGH THIS EVENING.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 PM FRIDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
1228 PM CDT FRI MAY 4 2012
.SHORT TERM.../TODAY/
WEAK SYNOPTIC SCALE FORCING ASSOCIATED WITH ELONGATED SHORT WAVE
FROM WRN GREAT LAKES INTO TX PANHANDLE CONTINUES TO COMBINE WITH
MOISTURE CONVERGENCE ALONG 305K ISENT SURFACE TO PRODUCE SCATTERED
THUNDERSTORMS ACROSS SRN IA. ORIGINALLY THOUGHT MO MCS WOULD
INTERCEPT INFLOW KEEPING CONVERGENCE TO OUR SOUTH...HOWEVER LARGER
SCALE FORCING HAS APPARENTLY ALLOWED MORE DEVELOPMENT FARTHER
NORTH. ELEVATED CAPES UP TO 2500 J/KG AND LITTLE CINH WITH ADEQUATE
EFFECTIVE SHEAR CONTINUE TO PRODUCE SUPERCELLS WITH HEAVY RAIN
POTENTIAL. EXPECT BOTH SEVERE AND HEAVY RAIN THREATS TO DIMINISH BY
SUNRISE HOWEVER AS 305K FLOW CONTINUES TO VEER AND WEAKEN...REDUCING
CONVERGENCE.
QUESTION THEN TURNS TO REDEVELOPMENT LATER IN THE DAY. NAM AND GFS
BOTH BUILD ANOTHER ROUND OF 2500-3000 J/KG MLCAPES AND LITTLE CINH
INTO THE HEART OF IA AS WARM FRONT GRADUALLY SURGES BACK NORTHWARD
INTO THE STATE...CONNECTING TO WEAK SURFACE WAVE OVER SRN SD.
CONVERGENCE WITH THIS FEATURE WILL BE WEAK BUT HRRR AND NMM WRF TRY
TO DEVELOP ISOLATED CONVECTION DURING PEAK HEATING. NOT COMFORTABLE
GOING DRY SO HAVE GONE WITH SLIGHT CHANCES DURING THE AFTERNOON.
BETTER SVR THREAT WOULD BE OVER NRN IA WHERE 0-6KM SHEAR IS THE
HIGHEST. IF ANY STORMS DO FORM THEY WOULD AGAIN BE SLOW MOVING WITH
WEAK H85/H3 WINDS AND B2K SUPERCELL MOTION. LIGHT WINDS...VERY
SEASONALLY HIGH PWS AND DEEP WARM CLOUD DEPTHS COULD ALSO PRODUCE
ISOLATED HEAVY RAINS IF ANYTHING DOES DEVELOP.
.LONG TERM.../TONIGHT THROUGH THURSDAY/
LONG TERM FORECAST IS A CHALLENGE ESPECIALLY EARLY IN THE PERIOD
UNTIL THE SYNOPTIC FRONT MOVES THROUGH SUNDAY NIGHT INTO MONDAY.
MESOSCALE FEATURES WILL BE A MAJOR FACTOR UNTIL THEN...SO WILL
HAVE TO GIVE DUE CONSIDERATION TO THEM IN ADDITION TO SYNOPTIC
FEATURES. IN ADDITION...SEVERE WEATHER AND HEAVY RAIN WILL REMAIN
A THREAT UNTIL THE SYNOPTIC FRONT MOVES THROUGH LATE THIS
WEEKEND.
FOR TONIGHT...ANY STORMS THAT DO DEVELOP WILL HAVE THE POTENTIAL
TO BE SEVERE. IN ADDITION...THEY WOULD BE EFFICIENT RAINFALL
PRODUCERS. FORECAST SOUNDINGS INDICATE PRECIPITABLE WATER VALUES
WILL BE AS HIGH AS THE 1.5 TO 1.75 RANGE TONIGHT...WHICH WOULD BE
BETWEEN THE 99TH PERCENTILE AND THE RECORD HIGH VALUES FOR THIS
TIME OF YEAR. IN ADDITION...COMPARISON OF MEAN STORM MOTION AND
CORFIDI VECTORS INDICATE THAT ANY STORMS WHICH DO DEVELOP WILL
EITHER BE SLOW MOVERS OR WILL TRAIN. THUS HAVE ADDED MENTION OF
HEAVY RAIN IN TONIGHT/S FORECAST. WILL LEAVE THE DECISION OF A
POTENTIAL FLASH FLOOD WATCH WITH THE DAY SHIFT.
THUNDERSTORM CHANCES WILL BE LOWER DURING THE DAY ON
SATURDAY...BUT WILL RETURN AGAIN SATURDAY NIGHT. ALTHOUGH
FORECAST SOUNDINGS INDICATE LOWER PRECIPITABLE WATER VALUES THAN
THOSE EXPECTED FOR TONIGHT...HEAVY RAIN WILL AGAIN BE A
POSSIBILITY IN ADDITION TO SEVERE WEATHER. OF COURSE...MESOSCALE
FEATURES MAY HELP ENHANCE ANY THUNDERSTORM ACTIVITY.
UPPER AIR PATTERN AND SENSIBLE WEATHER UNDERGO A SIGNIFICANT
SHIFT SUNDAY NIGHT INTO MONDAY...AS THE SYNOPTIC FRONT MOVES
THROUGH AND THEN AN UPPER LEVEL LOW SHIFTS SOUTHWARD FROM CANADA
TO THE NORTHERN CONUS. OVERALL...WEATHER WILL BECOME DRIER BUT
SOME PCPN IS POSSIBLE IN ASSOCIATION WITH THE UPPER LEVEL LOW. AT
THIS TIME THE BEST CHANCES FOR PCPN WOULD BE TO OUR NORTH.
&&
.AVIATION...04/18Z
MOIST SOUTHEASTERLY FLOW WILL CONTINUE THROUGH THE 24 HOUR TAF
PERIOD...BUT NOT A LOT OF STRONG FORCING FOR ORGANIZED INTENSE
THUNDERSTORMS. CONVECTION HAS DISRUPTED WARM FRONT LEAVING A
BOUNDARY IN NORTH IOWA AND NORTH MISSOURI. THUNDERSTORMS MOST LIKELY
TO WORK EAST ACROSS NORTHERN IOWA THIS EVENING...SO HAVE INCLUDED
THEM IN TAFS...FOR KDMX AND KOTM...CHANCES ARE TOO SMALL TO INCLUDE
AT THIS TIME. GIVEN HIGH MOISTURE EXPECT FOG AND/OR LOW STRATUS TO
DEVELOP AGAIN OVERNIGHT ACROSS STATE...AND THIS WILL TAKE SOME TIME
TO BURN OFF SATURDAY MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SMALL
LONG TERM...ZOGG
AVIATION...JUNGBLUTH
AREA FORECAST DISCUSSION
NWS TOPEKA KS
346 PM CDT FRI MAY 4 2012
.DISCUSSION...
AN UPPER LEVEL TROUGH ACROSS THE WESTERN CONUS THIS AFTERNOON WILL
LIFT NORTHEAST INTO THE NORTHERN AND CENTRAL HIGH PLAINS BY SATURDAY
AFTERNOON. A DOWNSTREAM UPPER LEVEL RIDGE WILL AMPLIFY ACROSS THE
EASTERN CENTRAL AND SOUTHERN PLAINS TONIGHT THROUGH SATURDAY.
A WEAK SOUTHERN STREAM UPPER LEVEL TROUGH WAS LOCATED ACROSS CENTRAL
OK LATE THIS AFTERNOON AND WILL LIFT NORTHEAST INTO SOUTHWEST MO
THIS EVENING. THERE MAY BE ENOUGH ASCENT AHEAD OF THE WEAK H5 TROUGH
TO CAUSE ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP THIS
AFTERNOON ACROSS SOUTHEAST KS AND SOUTHWEST MO. FORECAST SOUNDINGS
ACROSS THE CWA SHOW A STRONG CAP...WHICH WILL PREVENT SFC BASED
PARCELS REACHING THEIR LFC...DUE TO AN EML AT 830 MB. THE 16Z RUN OF
THE HRRR IS THE ONLY NUMERICAL MODEL SHOWING ISOLATED THUNDERSTORMS
DEVELOPING ACROSS SOUTHEAST KS AND SOUTHWEST MO...SOUTH AND
SOUTHEAST OF THE CWA THIS AFTERNOON. I KEPT 14 POPS ACROSS THE
SOUTHEAST COUNTIES OF THE CWA THIS AFTERNOON AND TONIGHT...JUST IN
CASE THERE WAS ENOUGH ASCENT FOR PARCELS ABOVE THE CAPPING INVERSION
TO REACH THEIR LFC. IF THESE ELEVATED STORMS DEVELOP THEY WILL NOT
BE SEVERE ACROSS THE SOUTHEAST COUNTIES OF THE CWA.
TONIGHT...THERE MAY BE SOME WEAK ISENTROPIC LIFT AFTER 3Z FOR SCT TO
STRATUS TO DEVELOP BUT AFTER 10Z...850MB WINDS VEER MORE TO THE
SOUTHWEST...THUS ANY STRATUS MAY DISSIPATE AFTER 10Z SAT. OVERNIGHT
LOWS WILL ONLY DROP INTO THE UPPER 60S TO LOWER 70S.
SATURDAY...850MB WINDS WILL BACK TO THE SOUTH DURING THE MID AND
LATE MORNING HOURS. DEEP MOISTURE ADVECTION WILL CAUSE SFC DEWPOINTS
TO BE IN THE UPPER 60S TO LOWER 70S DURING THE AFTERNOON HOURS.
FORECAST SOUNDINGS CONTINUE TO SHOW THE EML KEEPING A MODERATELY
STRONG CAP IN PLACE ACROSS THE CWA. THE H5 TROUGH OVER THE WESTERN
CONUS WILL LIFT NORTHEAST INTO THE NORTHERN HIGH PLAINS DURING THE
LATE AFTERNOON HOURS. THE ONLY SFC CONVERGENCE AND ASCENT WILL BE
ALONG AND NORTH OF THE SFC BOUNDARY ACROSS NORTHERN AND WESTERN NE
DURING THE LATE AFTERNOON HOURS...WHERE SCATTERED THUNDERSTORMS WILL
DEVELOP. EXPECT A WARM AND HUMID DAY WITH HIGHS IN THE UPPER 80S TO
LOWER 90S...AND AFTERNOON HEAT INDICES IN MID TO UPPER 90S.
GARGAN
MODELS CONTINUE TO DIFFER ON FRONTAL POSITION/SPEED OF MOVEMENT
ACROSS THE CWA THROUGH SUNDAY. THE NAM CONTINUES TO BE THE FASTER
AMONG THE MODELS WITH THE SPEED OF THE FRONT...AND GFS THE SLOWER.
WENT WITH A COMPROMISE AMONG MODELS BRINGING THE FRONT INTO THE FAR
NORTHWEST CORNER SUNDAY MORNING AND EXITING THE SOUTHEAST CORNER
SUNDAY EVENING. STILL EXPECTED THE DEVELOPMENT OF THUNDERSTORM
COMPLEX WELL NORTH OF THE CWA SATURDAY EVENING...BUT APPEARS ONLY A
LOW END CHC/SCHC POPS WARRANTED ACROSS AREAS NORTH OF I 70 THROUGH
SUNRISE SUNDAY. THE REMAINDER OF THE CWA SHOULD BE DRY. AS THE FRONT
MOVES INTO AND ACROSS THE CWA SUNDAY/SUNDAY EVENING...THE CHANCE FOR
THUNDERSTORMS WILL INCREASE...MAINLY ACROSS AREAS ALONG AND EAST OF
HIGHWAY 99 FROM MID AFTERNOON INTO THE EVENING. ALTHOUGH SHEAR WILL
BE WEAK...MLCAPE WILL BE VERY HIGH TO EXTREME WITH VALUES IN
ACROSS THE SOUTHEAST 1/2 OF THE CWA COMMONLY IN THE RANGE OF
3500-4500 J/KG. THEREFORE...STILL A THREAT FOR LARGE HAIL AND
STRONG GUSTY WINDS ALONG AND AHEAD OF THE FRONT FROM MID AFTERNOON
INTO THE EARLY EVENING OVER THE NORTHEAST AND EAST CENTRAL
COUNTIES. THE FRONT WILL BEGIN TO BRING IN COOLER AND DRIER AIR
INTO THE NORTHWEST CWA SUNDAY WITH HIGHS IN THE MIDDLE 70S
NORTHWEST TO STILL THE MIDDLE 80S SOUTHEAST AHEAD OF THE FRONT AT
PEAK HEATING.
CHANCES FOR SHOWERS AND THUNDERSTORMS WILL STEADILY DECREASE WEST TO
EAST ACROSS THE CWA SUNDAY EVENING...WITH DRY CONDITIONS ALL AREAS
LATER IN THE NIGHT. HAVE LOWERED LOWS INTO THE MIDDLE 50S TO NEAR 60.
THE EXTENDED FORECAST FROM MONDAY INTO THURSDAY STILL LOOKS TO BE
DOMINATED FROM COOLER HIGH PRESSURE WITH PLEASANT HIGHS IN THE 70S
AND LOWS IN THE UPPER 40S AND LOWER 50S EACH DAY. AS THE LARGE SFC
RIDGE SHIFTS FURTHER EAST BY LATE THURSDAY...MOISTURE WHICH WILL BE
POOLING TO THE SOUTH AND WEST OF THE AREA WILL GET ADVECTED
NORTHWARD INTO THE AREA FRIDAY. AS A SHORTWAVE TROUGH APPROACHES
FROM THE SOUTHWEST...THE CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
BE ON INCREASE AT THAT TIME. 63
&&
.AVIATION...
EXPECT VFR CONDITIONS FOR MUCH OF THE NEXT 24 HOURS. SCT TO AT
TIMES BKN CU WILL DEVELOP AT THE TAF SITES THIS AFTERNOON WITH
CU BASES OF 3,000 TO 4,000 FEET. THE CU SHOULD DISSIPATE AFTER
SUNSET. SCATTERED STRATUS WITH MVFR CEILINGS MAY DEVELOP AFTER 8Z SAT AND
MIX OUT AROUND 15Z SAT. THERE MAY BE BE SOME PERIODS OF BKN
STRATUS WITH MVFR CEILINGS BETWEEN 10Z AND 14Z SAT. WINDS WILL BE
SOUTH-SOUTHEAST UNDER 12 KTS THROUGH THE PERIOD.
GARGAN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
657 PM EDT FRI MAY 4 2012
.SYNOPSIS...
A SOUTHWARD COLD FRONT WILL BRING THUNDERSTORMS TONIGHT. CANADIAN HIGH
PRESSURE WILL FOLLOW TO PROVIDE DRY, SEASONABLE CONDITIONS FOR THE
REST OF THE WEEKEND.
&&
.NEAR TERM /THROUGH SATURDAY/...
BLEND OF RECENT RADAR DATA AND RAP/HRRR/MODEL OUTPUT SHOW
PREFRONTAL BANDS OF NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS
WILL MOVE SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY TONIGHT.
THE LAST OF THE SHOWERS SHOULD EXIT INTO CENTRAL WEST VIRGINIA
AROUND DAYBREAK SATURDAY. THE REST OF SATURDAY WILL BE DRY WITH
SOME SUNSHINE. FORECASTED TEMPERATURES TO BE NOT AS WARM AS THE
THURSDAY AND FRIDAY, BUT STILL MORE THAN 5 DEGREES WARMER THAN
NORMAL.
SOME THUNDERSTORMS EARLY TONIGHT CAN PRODUCE A BRIEF EPISODE OF
GUSTY WINDS, HAIL, AND HEAVY DOWNPOURS. REGARDING SEVERE
POTENTIAL, INSTABILITY APPEARS STRONG ENOUGH, BUT VERTICAL SHEAR
APPEARS RATHER WEAK. HENCE THAT IS WHY STORM CHARACTERISTICS WILL
BE MORE PULSE-LIKE.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
MODELS IN GENERAL AGREEMENT THAT RIDGE SURFACE AND ALOFT WILL
BRING MILD AND DRY CONDITIONS THROUGH SUNDAY. OPTED FOR SLOWER GFS
SOLUTION SUNDAY NIGHT AND MONDAY WITH RETURN NORTHWARD OF BOUNDARY
AND MOISTURE AHEAD OF A FAIRLY STRONG SURFACE LOW AND COLD FRONT
FOR MONDAY. THIS IS MORE IN LINE WITH 12Z ECMWF AND A BLEND OF
GFS/ECMWF USED.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
12Z GFS SHOWS A CLOSED UPPER LOW AND ASSOCIATED SURFACE LOW TRACKING
NORTH OF THE GREAT LAKES EARLY IN THE WEEK AND REACHING SOUTHERN
QUEBEC LATE WEDNESDAY. OLD 00Z ECMWF TRACK DIGS THE UPPER LOW MUCH
FURTHER SOUTHWARD INTO THE APPALACHIANS BY THURSDAY. LEANED TOWARD
HPC PROGS WHICH ARE CLOSER TO GFS SOLUTION.
FORECAST LIKELY POPS FOR SHOWERS AND THUNDER MONDAY NIGHT INTO
TUESDAY WITH FRONTAL PASSAGE. TAPERED POPS TO SCATTERED COVERAGE
TUESDAY NIGHT INTO THURSDAY AS SYSTEM MAKES SLOW EASTWARD PROGRESS.
DRY CONDITIONS ARE FORECAST BY FRIDAY AS SURFACE HIGH BUILDS IN
FROM THE WEST.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
BLEND OF RECENT RADAR DATA AND HRRR MODEL OUTPUT SHOWS PREFRONTAL BANDS
OF MVFR SHOWERS AND SCATTERED IFR THUNDERSTORMS WILL MOVE
SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY THROUGH ABOUT 08Z.
AREAS OF POST-FRONTAL POST-RAIN IFR FOG AND STRATUS CAN DEVELOP
LATE TONIGHT. HIGH PRESSURE SUBSIDENCE AND DRYING, PLUS DAYTIME
VERTICAL MIXING, WILL IMPROVE CONDITIONS TO VFR CUMULUS BY
SATURDAY AFTERNOON.
SURFACE WINDS WILL BECOME NORTHWEST 6-10 KTS LATE TONIGHT AND
SATURDAY. HIGHER GUSTS ARE POSSIBLE WITH THUNDERSTORMS TONIGHT.
.OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY...
HIGH PRESSURE WILL PROVIDE VFR CONDITIONS SATURDAY NIGHT THROUGH
EARLY MONDAY. THE NEXT LOW PRESSURE SYSTEM WILL MOVE ACROSS THE
LOWER GREAT LAKES AND INTO NEW ENGLAND BY WEDNESDAY. SCATTERED
SHOWERS AND STORMS WILL BRING THE POTENTIAL FOR RESTRICTIONS LATE
MONDAY THROUGH WEDNESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DULUTH MN
326 PM CDT FRI MAY 4 2012
.SHORT TERM...
CLOUDY AND WET CONDITIONS WILL PREVAIL THROUGH THE WEEKEND AS THE
WESTERN GREAT LAKES REGION REMAINS SITUATED BETWEEN CANADIAN HIGH
PRESSURE ANCHORED OVER HUDSON BAY AND AN APPROACHING LONG WAVE
TROUGH IN THE WEST. FOCUS FOR RAIN OVERNIGHT WILL BE ALONG A
CORRIDOR OF FGEN ON THE NOSE OF A REGION OF H85 WAA/THETA-E
ADVECTION. HOWEVER...TIMING THE RAIN AND PLACEMENT OF THE GREATEST
QPF TONIGHT/EARLY SAT IS DIFFICULT WITH MODELS SHOWING LARGE
DIFFERENCES IN MOISTURE PROFILES AND OMEGA FIELDS. ALTHOUGH EXPECT
ALL AREAS TO SEE AT LEAST SOME LIGHT RAIN...HAVE KEPT BROADBRUSH
50-60 POPS THROUGH THE NIGHT DUE TO UNCERTAINTY IN TIMING AND
LOCATION OF GREATEST RAINFALL.
THE RAIN WILL DIMINISH BRIEFLY ON SATURDAY...BEFORE A MORE ORGANIZED
AREA OF HEAVIER RAIN SPREADS NORTH AND EAST OVER THE REGION LATE
SATURDAY NIGHT. MODELS SHOWING BETTER AGREEMENT THAT THE LONG
WAVE TROUGH DEEPENS INTO A CUT OFF LOW OVER SASKATCHEWAN SAT
NIGHT...RESULTING IN A SRLY LOW LEVEL JET AND STRONG MOISTURE
TRANSPORT INTO THE NORTHERN PLAINS. AT THIS TIME...MODELS ARE
SUGGESTING WIDESPREAD RAINFALL AMOUNTS OF A HALF TO ONE INCH WILL
BE FOUND SAT NIGHT/SUNDAY.
EXTENDED...SUNDAY THROUGH FRIDAY...
UNSETTLED WEATHER PATTERN TO START THIS PERIOD AS MID LVL FLOW
DELIVERS INCREASING ASCENT. THIS OCCURS AS UPPER TROF ADVECTS EAST
FROM NRN PLAINS WITH ORGANIZED CONVERGENCE FOCUSING NEAR LOW LVL
FRONTAL BDRY. A WELL DEVELOPED DRY SLOT SHOULD CROSS THE REGION
MONDAY ALLOWING SUBSTANTIAL SFC WARMING. THIS WILL BE FOLLOWED BY
DEEPENING UPPER TROF MON NIGHT/TUESDAY. DEEP CYCLONIC CURVATURE
SFC/ALOFT SHOULD PROMOTE DEVELOPMENT OF A LARGE CANOPY OF LOW CLOUD
COVER WITH SCTD SHOWERS.MAY NEED TO TREND COVERAGE UPWARDS AS WE GET
CLOSER TO EVENT DUE TO ANOMALOUS NATURE OF MID LVL SYSTEM. WEDNESDAY
SHOULD FEATURE A DRYING TREND AND LATER UPDATES MAY BE ABLE TO
ACCELERATE THAT IDEA IF MID LVL TROF IS A BIT FASTER. DRY SPELL
LOOKS POSSIBLE FROM WED AFTN TO THURSDAY EVENING BEFORE NEXT FRONTAL
SYSTEM MOVES INTO REGION.
&&
.PREV DISCUSSION... /ISSUED 112 PM CDT FRI MAY 4 2012/
AVIATION...18Z TAF ISSUANCE...
LARGE CANOPY OF STRATUS COVERS ALL TERMINALS EXCEPT KHYR. EXPECT MVFR
CEILINGS TO CONTINUE AS BDRY LYR WARMING LIFTS BASES...EXCEPT AT KDLH
WHERE MOIST NE FLOW OFF LAKE SUPERIOR HAS LIMITED IMPROVEMENT SO
FAR. HOWEVER...DRIER AIR IS SPREADING DOWN LAKE ACCORDING TO
LATEST RUC13 ANALYSIS SO CL GS MAY CONTINUE TO LIFT THRU AFTN AT
KDLH. WIDESPREAD RAIN WILL SPREAD FROM WEST TO EAST LATER THIS
EVENING AND CONTINUE THROUGH TAF PERIOD. SATURATION/NOCTURNAL
COOLING SHOULD BRING IFR AND LOWER CLGS/VIS TO MOST AREAS
OVERNIGHT.
&&
.POINT TEMPS/POPS...
DLH 39 49 40 50 / 60 30 50 70
INL 41 57 41 54 / 50 20 50 60
BRD 45 62 46 61 / 60 30 70 50
HYR 44 61 43 60 / 60 40 40 70
ASX 40 48 41 55 / 60 40 30 70
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 AM CDT SUNDAY FOR LSZ121-142>148.
&&
$$
SHORT TERM...GRANING
LONG TERM....CANNON
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
112 PM CDT FRI MAY 4 2012
.AVIATION...18Z TAF ISSUANCE...
LARGE CANOPY OF STRATUS COVERS ALL TERMINALS EXCEPT KHYR. EXPECT MVFR
CEILINGS TO CONTINUE AS BDRY LYR WARMING LIFTS BASES...EXCEPT AT KDLH
WHERE MOIST NE FLOW OFF LAKE SUPERIOR HAS LIMITED IMPROVEMENT SO
FAR. HOWEVER...DRIER AIR IS SPREADING DOWN LAKE ACCORDING TO
LATEST RUC13 ANALYSIS SO CLGS MAY CONTINUE TO LIFT THRU AFTN AT
KDLH. WIDESPREAD RAIN WILL SPREAD FROM WEST TO EAST LATER THIS
EVENING AND CONTINUE THROUGH TAF PERIOD. SATURATION/NOCTURNAL
COOLING SHOULD BRING IFR AND LOWER CLGS/VIS TO MOST AREAS
OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 1040 AM CDT FRI MAY 4 2012/
UPDATE...
VISIBLE SAT IMAGERY SHOWS A SHARP CUT OFF IN THE CLOUD COVER OVER
WISCONSIN. HAVE UPDATED FORECAST TO REFLECT THE CLEAR SKIES OVER
PORTIONS OF THE CHEQUAMEGON NATIONAL FOREST. THE INCREASE IN SUN
TODAY IN THIS REGION WILL ALSO HELP TO RISE TEMPERATURES...SO HAVE
INCREASED MAX TEMPERATURES AND LOWERED MINIMUM RELATIVE HUMIDITIES
OVER WASHBURN/SAWYER/PRICE COUNTIES TODAY AS WELL.
ALSO ISSUED A DENSE FOG ADVISORY FOR NORTH SHORE OF LAKE SUPERIOR
WHERE COOL TEMPERATES AND AN ONSHORE FLOW WILL KEEP LOW CLOUDS
WITH FOG AND DRIZZLE THROUGH THE DAY.
PREV DISCUSSION... /ISSUED 655 AM CDT FRI MAY 4 2012/
AVIATION.../12Z TAF ISSUANCE/
LOW CLOUDS AND AREAS OF FOG WILL AFFECT MOST OF THE NORTHLAND THIS
MORNING. HOWEVER LATEST NAM12 GUIDANCE SUGGEST THE FOG SHOULD LIFT
AND CLOUD SHOULD SCTR OUT BY MIDDAY TODAY. AN UPPER LEVEL
SHORTWAVE WILL THEN TRACK ACROSS THE UPPER MIDWEST...BRINGING
AREAS OF LIGHT RAIN TO THE FCST AREA THIS AFTERNOON AND TONIGHT.
ISOLD STORMS ARE POSSIBLE...MAINLY ACROSS OUR SRN ZONES.
PREV DISCUSSION... /ISSUED 652 AM CDT FRI MAY 4 2012/
UPDATE...
INCREASED POPS THROUGH THIS MORNING BASED ON HOW QUICKLY RAIN IS
MOVING OUT OF EASTERN NORTH DAKOTA INTO NORTHWESTERN MINNESOTA.
ALSO CONTINUED PATCHY DRIZZLE THROUGH LATE THIS MORNING.
PREV DISCUSSION... /ISSUED 358 AM CDT FRI MAY 4 2012/
SHORT TERM [NOW - SATURDAY]...
TODAY...A VERY LOW OVERCAST STRATUS DECK THAT DEVELOPED NEAR LAKE
SUPERIOR EARLIER IN THE NIGHT WILL CONTINUE TO EXPAND WESTWARD
THIS MORNING...COVERING MUCH OF THE FA BY DAWN. THERE HAVE BEEN
SOME REPORTS OF FOG AND DRIZZLE CLOSER TO LAKE SUPERIOR EARLY THIS
MORNING. THE FOG COULD PERSIST INTO THE LATE MORNING. HIGH CLOUDS
WILL MOVE OVER THE FA THIS MORNING...TOO...SO THE FA SHOULD REMAIN
MOSTLY CLOUDY EVEN IF THE LOW STRATUS DECK BEGINS TO BREAK UP.
LIGHT TO BREEZY EASTERLY WINDS WILL DEVELOP THIS MORNING AS HIGH
PRESSURE DRIFTS OVER MANITOBA/ONTARIO AND LOW PRESSURE DEVELOPS IN
THE CENTRAL AND NORTHERN HIGH PLAINS. THE STRONGEST WINDS...WHICH
WILL BE AROUND 15 MPH WITH GUSTS UP TO 25 MPH...SHOULD BE FROM THE
TWIN PORTS TO BRAINERD AREA. THE LOW PRESSURE IN THE PLAINS COULD
BRING RAIN SHOWERS TO THE FA THIS MORNING AND
AFTERNOON AS THE TROUGH APPROACHES THE WESTERN FA AND A SHORTWAVE
MOVES THROUGH NORTH DAKOTA AND THEN NORTHERN MINNESOTA. THERE IS A
LACK OF AGREEMENT BETWEEN THE MODELS HOWEVER...WITH THE GEM
HOLDING OFF PCPN THROUGH THIS AFTERNOON...WHILE THE GFS BRINGS
PLENTY OF PCPN OVER THE FA. THEREFORE...HELD OFF ON INCREASING
POPS TO LIKELY...BUT MAY NEED TO MAKE SOME CHANGES TOWARDS THE END
OF THE SHIFT AFTER REVIEWING TRENDS. THE MODELS DO PROVIDE A
LITTLE SUPPORT FOR THUNDER THIS AFTERNOON...MAINLY ACROSS THE FAR
SOUTHWESTERN FA WHERE THERE MAY A LITTLE INSTABILITY...SLIGHTLY
NEGATIVE LIFTED INDICES...AND SLIGHTLY NEGATIVE SHOWALTER VALUES.
OTHERWISE...THINK MOST PCPN WILL BE FREE OF THUNDER. TEMPERATURES
WILL BE ON THE COOL SIDE ACROSS THE NORTHERN AND CENTRAL FA TODAY
DUE TO THE WINDS OFF THE LAKE...BUT THE SOUTHERN FA SHOULD CLIMB
INTO THE 60S.
TONIGHT...THE TROUGH MAY MOVE THROUGH THE FA TONIGHT...WITH THE
MODELS GIVING THE FA PCPN. HOWEVER...THERE IS STILL SOME MODEL
DISAGREEMENT...SO DID NOT INCREASE POPS TO LIKELY. THE MODELS
SUPPORT THE POSSIBILITY OF THUNDER ACROSS THE SOUTHERN FA.
SATURDAY...THE SHOWERS COULD LINGER INTO SATURDAY...BUT THE LATEST
GFS AND GEM INDICATE DRY WEATHER BY THE AFTERNOON...SO LOWERED
POPS. MAY NEED TO CONTINUE THIS TREND AND FORECAST DRY WEATHER
SATURDAY AFTERNOON IF THE ECMWF BACKS OFF ON ITS WETTER SOLUTION.
IT COMES DOWN TO A TROUGH THAT WILL BE LIFTING IN THE WESTERN
US...AND LOW PRESSURE ORGANIZING IN THE PLAINS. THE ECMWF IS
QUICKER AT THIS THAN THE GEM AND GFS. THE EASTERLY WINDS WILL
CONTINUE SATURDAY...RESULTING IN COOLER TEMPERATURES NEAR LAKE
SUPERIOR...BUT THE WESTERN AND SOUTHERN FA SHOULD SEE HIGH
TEMPERATURES NEAR 60 DEGREES.
LONG TERM [SATURDAY NIGHT - THURSDAY]...
UNSETTLED CONDITIONS ARE EXPECTED FOR LATE THIS WEEKEND ACROSS THE
NORTHLAND WITH A COLD FRONT AND UPPER LEVEL SHORTWAVE EXPECTED
TO PROPAGATE EWD ACROSS THE UPPER MIDWEST. THE MODELS ARE IN
FAIRLY GOOD AGREEMENT IN SPREADING SHOWERS...AND POSSIBLY SOME
THUNDERSTORMS...FROM SOUTHWEST TO NORTHEAST ACROSS OUR CWA
SATURDAY NIGHT. THE PRECIPITATION WILL CONTINUE ACROSS OUR FCST
WITH THE FRONT OVER THE FCST AREA ON SUNDAY. HOWEVER THE PRECIP
COULD START TAPERING ACROSS OUR WRN ZONES AS EARLY AS SUNDAY
AFTERNOON. THE COLD FRONT AND SHORTWAVE SHOULD MOVE EAST OF THE
NORTHLAND SUNDAY NIGHT...WITH SCTD SHOWERS LINGERING ACROSS OUR
ERN AND NRN ZONES. THE MODELS THEN SHOW A FAIRLY STRONG UPPER
LEVEL LOW/TROUGH OVER SCNTL CANADA DIGGING SEWD ACROSS THE UPPER
MIDWEST MONDAY THROUGH TUESDAY. THE COLD AIR ALOFT ASSOCIATED WITH
THE TROUGH WILL COMBINE WITH MID-SPRING SFC TEMPS RESULTING IN A
CONTINUANCE OF SCATTERED SHOWERS AND STORMS. A RIDGE WILL BUILD
BACK OVER THE REGION WEDNESDAY AND THURSDAY...RESULTING IN A
RETURN TO MAINLY DRY CONDITIONS.
AVIATION...06Z TAF ISSUANCE...
EASTERLY SURFACE WINDS COMING OFF OF LAKE SUPERIOR HAS CREATED
FOGGY CONDITIONS AND A LOW STRATUS DECK THAT WILL AFFECT
KDLH/KHIB/KHYR AND BRING THEM INTO IFR CONDITIONS. FRIDAY
AFTERNOON WILL BE GUSTY AS HIGH PRESSURE FROM THE NORTHWEST PUSHES
SOUTHEAST TIGHTENING THE PRESSURE GRADIENT ACROSS THE AREA. LOWER
CLOUDS WILL MOVE IN TOMORROW MORNING AND RAIN INTO THE AREA FRIDAY
AFTERNOON AND EVENING. CONDITIONS ARE FORECAST TO BE VFR...BUT A
DEGRADATION OF CONDITIONS MAY BE POSSIBLE LATER.
&&
.POINT TEMPS/POPS...
DLH 38 50 40 52 / 50 30 50 60
INL 40 58 41 59 / 40 20 50 60
BRD 43 63 47 62 / 50 30 70 60
HYR 44 62 43 60 / 50 40 40 60
ASX 39 49 41 55 / 50 40 50 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL 5 PM CDT THIS AFTERNOON FOR MNZ020-021.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 AM CDT SUNDAY FOR LSZ121-142>148.
&&
$$
AVIATION...CANNON
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
349 PM CDT Fri May 4 2012
.DISCUSSION...
ain concerns continue to be thunderstorm chances with a multitude
of outflow boundaries to be concerned about.
This Evening and Tonight:
The strongest outflow boundary and the one that seems to have the
best chance of initiating convection is still residing from near
Paola to south of Clinton, MO. There has been some deeper cloud
development in the vicinity of the boundary and given the extreme
instability, MUCAPE approaching 5,000 J/kg, if something could
develop it would likely become severe. But limited deep layer shear
would inhibit much organization so more multicell clusters would be
the most likely convective mode. Forecast soundings offer a mixed
scenario. The NAM maintains a fairly strong cap and inhibits
convection. The RUC weakens the cap to the point that mixed layer
parcel would be uninhibited and we`d be off to the races. Something
in between is probably the best scenario in which case a little
better forcing would be needed to break the cap. That said the
presence of the boundary within the extreme instability warrants at
least a small mention of thunderstorms. Forecast soundings in the
southern portions of the forecast area also show some mid level dry
air. All that said, should any storm get going they could easily
become severe with damaging winds and large hail possible. Also,
with ample amounts of moisture available any storm could drop
copious amounts of rainfall over a localized area.
During the overnight hours, storms may fire again in far northern MO
or southern IA and NE and move into northern MO. This area is not as
unstable as it is still recovering from morning convection but
3-4,000 J/kg could still be realized by late this afternoon. Shear
looks weak in this area so if any storms can get going and/or move
into northern MO they would likely be disorganized. There is still
ample moisture in this area and some areas received heavy rain so
any storm could easily produce additional flooding problems.
Saturday:
Hot and humid conditions will persist with heat indices in the mid
90s. This is very unseasonal and could pose problems for those who
are most sensitive to heat. Otherwise, it looks like the area should
be capped for most of the day inhibiting convective chances until
closer to sunset. By the evening and overnight hours we may see some
storms move into or develop in northern MO. Instability should be
around 3,000 J/kg but again shear looks marginal at best for storm
organization. So a more disorganized storm mode would be expected
with hail and damaging winds possible should storms impact the area.
Sunday:
Extreme instability is expected to build back into the forecast area
by Sunday afternoon and evening with potential 4-5,000 J/kg MUCAPE to
work with. Models differ a little with the timing of the frontal
boundary with the NAM bringing the boundary into NW MO late Sunday
morning. The GFS is little slower, holding it up until the evening
hours. Shear continues to looks rather weak in the warm sector of
the system which would limit storm organization. But with the
extreme instability and front to act as a trigger thunderstorms are
expected to develop during the afternoon hours and could easily
become severe. It looks like the biggest hazards with this system
will be large hail and damaging winds as well locally heavy rainfall
given the copious amounts of moisture available.
CDB
Medium Range (Monday through Friday)...
Medium range models are in very good agreement on the overall
pattern aloft which is marked by a dry airmass with seasonal
temperatures. Except for the possibility of some lingering post
frontal showers over the eastern CWA Monday morning as high pressure
builds in from the Rockies.
The first portion of this forecast period will be dominated by an
upper trough which will deepen as it digs southeast from south
central Canada through the Great Lakes and Upper MS Valley. The
ECMWF and GEM are in closer agreement on the depth of the system/
timing and thus get a slight nod over the more progressive GFS. This
allows a bit more cold air advection to work its way southward out
of southern Canada but temperatures through mid week will still be
near seasonal averages. Could see some light instability showers
sneak across the IA/MO border Tuesday afternoon but have low
confidence this far out.
By the end of the work week expect to see warm air advection move
back in as the surface high departs and an upper ridge builds into
the Northern Plains. GFS/ECMWF similarly address the issue of a closed
upper low over either northern Mexico or the far southwestern U.S.
opening up and being lifted northeast by the developing
southwesterly mid/upper level flow. Both models lift this feature
into the Central Plains by Friday and interact with an approaching
cold front to generate convection. Despite both models being on the
same page with this feature have limited confidence in them as they
both tend to have issues in handling closed upper lows this far out.
So, best option is to use a blend of models and await the next
couple of model runs.
MJ
&&
.AVIATION...
For the 18Z TAFs, confidence is fairly high that the terminals will
remain dry/convection free due to strong capping. However, scattered
to broken MVFR ceilings have developed along/north of a weakening
outflow boundary. These lower ceilings are expected to lift and
become predominately scattered by later this afternoon leaving VFR
conditions for the first 6-9 hours of the valid period. A stronger
outflow boundary was draped well south of the terminals and it`s
possible convection could develop in the vicinity of that boundary
but this would not impact the terminals. During the overnight hours,
there is some indication that MVFR to IFR ceilings may form.
Confidence is very low regarding this possibility as well as the
timing and duration of any lower ceilings. Given the rich low level
moisture and the preponderance of guidance suggesting the lower
clouds have added broken MVFR ceilings to the TAFs.
CDB
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1223 PM CDT FRI MAY 4 2012
.AVIATION...18Z TAF. QUIET CONDITIONS CURRENTLY FORECAST FOR THIS
TAF PERIOD...WITH CONCERNS LYING WITH PRECIPITATION CHANCES LATER
TODAY/TONIGHT THEN FOG EARLY SAT MORNING. NOT EXPECTING ANY
SIGNIFICANT CHANGES WITH WIND DIRECTION THROUGH THE
PERIOD...REMAINING GENERALLY SOUTHEASTERLY...COULD SEE A FEW GUSTS
THIS AFTERNOON AND WILL BE VARIABLE EARLY TOMORROW
MORNING...OTHERWISE SPEEDS SHOULD BE AROUND 10 KTS. AT THIS POINT
STILL AM NOT CONFIDENT ENOUGH IN THE TERMINAL SEEING ANY
THUNDERSTORMS LATER ON TO PUT IN THE TAF...BUT WILL NEED TO KEEP
AN EYE ON IT. WITH NO CHANGE IN THE AIR MASS IN PLACE THROUGH THE
TAF PERIOD...NOT SEEING WHY THE TERMINAL WOULDNT SEE ANOTHER ROUND
OF FOG EARLY SAT MORNING...AND INSERTED IFR VISIBILITIES.
UPCOMING FORECASTS WILL TWEAK UP/DOWN AS NECESSARY.
&&
PREV DISCUSSION... /ISSUED 356 AM CDT FRI MAY 4 2012/
SHORT TERM...TODAY THROUGH SUNDAY NIGHT. AREAS OF FOG DEVELOPED
EARLY THIS MORNING IN PRESENCE OF LLVL MOISTURE AND NEARLY CALM OR
LIGHT EASTERLY WINDS. RUC13 SEEMS TO BE HANDLING THE VSBYS THE BEST
AND SUGGESTS PRETTY MUCH OUR ENTIRE CWA MAY BE UNDER INFLUENCE OF
DENSE FOG BY MORNING AND HAVE ISSUED DENSE FOG ADV UNTIL 8 AM FOR
ALL BUT OUR FAR NORTHERN COUNTIES WHERE TEMP/DP SPREAD IS
CURRENTLY GREATER...AND OUR FAR EASTERN CWA WHERE HIGH CLOUD COVER
FM CONVECTION TO OUR SE MAY HOLD UP VSBYS. WILL CONTINUE TO
MONITOR TRENDS EARLY THIS MORNING AS TO WHETHER HEADLINE NEEDS TO
BE EXPANDED OR NOT.
LOOKING FOR FOG TO BURN OFF AFTER DAYBREAK WITH DAYTIME
HEATING...THEN MUCH OF THE DAY IS LOOKING DRY. PATTERN ALOFT
FEATURED SOUTHWESTERLY FLOW WITH MID/UPPER TROUGH ORIENTED FM
ALBERTA INTO THE NORTHERN ROCKIES. JET STREAK NOSES INTO THE NC
ROCKIES TODAY WHILE A SERIES OF SUBTLE SHORTWAVE LIFT FM BASE OF
TROUGH. AT THE SURFACE WARM FRONT LIFTS INTO NC NEB THIS AFTERNOON
AND CONVERGENCE ALONG FRONT AND ENERGY ASSOCIATED WITH WAVES IS
EXPECTED TO INITIATE CONVECTION IN VCNTY OF FRONT. SREF INDICATES
AN AXIS OF INSTABILITY MUCAPES OF 4000 J/KG ACROSS EASTERN NEB/KS
WITH EFFECTIVE SHEAR AROUND 30KTS IN OUR CWA....INCREASING TO NEAR
50 KTS NEAR THE FRONTAL BOUNDARY JUST TO OUR NORTH. INITIATION
LOOKS TO BE JUST TO OUR NORTH ALONG THE FRONT FOR MAIN FOCUS WITH
ACTIVITY POTENTIALLY REACHING OUR NORTHERN ZONES TONIGHT. SOME
QUESTION AS TO WHETHER ACTIVITY MAY FIRE TO THE WEST NEAR THE DRY
LINE OR PERHAPS A DIFFERENTIAL HEATING BOUNDARY AS OCCURRED
YESTERDAY. FOR NOW WILL MAINTAIN MAIN FOCUS ALONG THE WARM FRONT
FOR TONIGHT...WITH SEVERE STORMS POSSIBLE. ALSO FOR TONIGHT...LLVL
FLOW REMAINS FM A LIGHT EASTERLY DIRECTION AS BOUNDARY SAGS SOUTH.
LOOKING AT POTENTIAL FOR FOG DEVELOPMENT AGAIN OVERNIGHT.
ON SATURDAY...WARM FRONT LIFTS NORTH IN AFTERNOON THEN COOL FRONT
PUSHES SOUTH SATURDAY NIGHT. LOOKING AT FAIRLY DECENT CHCS FOR
CONVECTION SATURDAY NIGHT AS THE STRONGER FRONT MOVES THROUGH AS
UPPER TROUGH CROSSES THE DAKOTAS. SEVERE STORMS ARE PROBABLE AGAIN
IN PRESENCE OF HIGH INSTABILITY AHEAD OF APPROACHING BOUNDARY AND
INCREASING SHEAR AS FRONT APPROACHES. COLD FRONT REACHES ALL BUT OUR
FAR SOUTHEAST CWA BY SUNDAY MORNING...AND HAVE LINGERED SOME
THUNDER INTO SUNDAY IN THIS AREA...WITH JUST RAIN SHOWERS FARTHER
NORTH AS INSTABILITY DIMINISHES.
COOLER...BREEZY/WINDY CONDITIONS SETTLE IN ON SUNDAY BEHIND THE
BOUNDARY WITH PCPN CHCS DECREASING DURING THE DAY. DRY WEATHER IS
FORECAST SUNDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY.
BY MONDAY...AN UPPER LEVEL RIDGE ACROSS THE EASTERN HALF OF THE
CONUS WILL BEGIN TO BREAK DOWN AS AN UPPER LEVEL TROUGH PUSHES
ACROSS THE CENTRAL CONUS. RIDGING WILL PUSH ACROSS THE NORTHWEST
COAST BEHIND THE TROUGH...WHILE A CLOSED UPPER LOW WILL PUSH ACROSS
THE SOUTHEAST ASSOCIATED WITH THE BASE OF THE TROUGH. AT THE SURFACE
LOW PRESSURE IS EXPECTED TO SHIFT ACROSS SOUTHERN CANADA WHILE HIGH
PRESSURE REMAINS CENTERED ACROSS THE ROCKIES.
THE UPPER LEVEL TROUGH IS EXPECTED TO DIVE SOUTHEAST ACROSS THE OHIO
RIVER VALLEY IN THE LONG TERM PERIOD. WITH THE SURFACE LOW FOLLOWING
SUIT...HIGH PRESSURE FROM CANADA WILL SLIDE SOUTHWARD INTO THE
CENTRAL PLAINS. COOLER 850 MB TEMPERATURES WILL ALSO SHIFT
SOUTHWARD...INDICATING COOLER HIGH TEMPERATURES IN THE LONG TERM
PERIOD. HOWEVER...850 MB TEMPERATURES STILL REMAIN NEAR 10 TO 13
DEGREES CELSIUS...SUGGESTING UPPER 60S TO LOWER 70S FOR HIGHS.
AT THIS TIME...THERE IS SOME DISCREPANCY AMONG MODELS REGARDING
PRECIPITATION CHANCES IN THE LONG TERM PERIOD. THE GFS REMAINS DRY
THROUGHOUT THE ENTIRE PERIOD...WHILE THE ECMWF TRIES TO GENERATE
SLIGHT POPS ACROSS THE PLAINS SPECIFICALLY TUESDAY. THE ECMWF TRIES
TO GENERATE A FEW SCATTERED POPS ACROSS THE FORECAST AREA...AS
COOLER AIR SLIDES SOUTH ALONG THE BACKSIDE OF THE TROUGH. ASSOCIATED
WITH THE LOCATION OF THE RIGHT ENTRANCE REGION OF UPPER LEVEL
JET...ENOUGH LIFT COULD BE POSSIBLE DURING THE AFTERNOON ON TUESDAY.
HOWEVER...BOTH MODELS SUGGEST DEWPOINTS IN THE 35 TO 40 DEGREE
RANGE. AT THIS POINT...DECIDED TO KEEP THE LONG TERM DRY UNTIL
MODELS CAN COME INTO BETTER AGREEMENT ON MOISTURE POTENTIAL AND
LOCATION OF THE UPPER LEVEL JET.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...ADO
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
512 PM EDT FRI MAY 4 2012
.SYNOPSIS...
WEAK UPPER LEVEL DISTURBANCES WILL AFFECT THE AREA LATE THIS
AFTERNOON AND EVENING AND AGAIN SATURDAY AFTERNOON AND EVENING.
A BACKDOOR COLD FRONT WILL SINK SOUTH ACROSS THE AREA SATURDAY
NIGHT AND SUNDAY MORNING. A COLD FRONT WILL CROSS THE AREA FROM
THE WEST ON WEDNESDAY. COOL HIGH PRESSURE WILL FOLLOW FOR LATE
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 430 PM FRIDAY...THE LATEST SEVERAL HRRR RUNS SHOW ISOLATED TO
SCATTERED SHOWERS/T-STORMS WILL DEVELOP OVER THE EASTERN PIEDMONT IN
THE NEXT HOUR...ADVECTING SOUTHEAST TOWARD THE COAST BY SUNSET.
RADAR COMPOSITES SHOW SOME MODEST MID-LEVEL ECHOES ACROSS CENTRAL
NORTH AND SOUTH CAROLINA. AS THE CONVECTIVE CAP WEAKENS THROUGH NOW
AND 23Z/6PM THIS ACTIVITY COULD FURTHER DEVELOP TO VERIFY THE HRRR`S
PREDICTION. COVERAGE SHOULD AMOUNT TO NO MORE THAN 1/4 OF THE
AREA...SO WE WILL MAINTAIN THE CURRENTLY 20 POPS THROUGH THE EVENING
HOURS. NO SIGNIFICANT CHANGES HAVE BEEN MADE TO OTHER WEATHER
ELEMENTS. PREVIOUS DISCUSSION FROM 130 PM FOLLOWS...
PLENTY OF HIGH LEVEL CLOUDINESS EXPECTED TO PASS ACROSS THE REGION
THROUGH THE EVENING...WITH SOME DIURNAL CU IN AN AREA CURRENTLY
DEFINED BY LIMITED LOW-LEVEL MOISTURE. THE HIGH CLOUDS HAVE HAD AN
IMPACT ON TEMPERATURES...BUT AREAS RECEIVING BREAKS HAVE CREPT INTO
THE MID 80S EARLY THIS AFTERNOON. A WEAK IMPULSE WILL PASS OFF THE
COAST THIS EVENING...AND ANOTHER WILL APPROACH FROM THE NW LATE
TONIGHT. PROSPECTS FOR CONVECTION DO NOT APPEAR TO BE THAT PROMISING
WITH ONLY WIDELY SCATTERED CONVECTION POSSIBLE. BETTER CHANCES FOR
SHOWERS WILL FOLLOW IN THE SHORT TERM PERIOD. LOWS TONIGHT WILL
RANGE FROM THE MID 60S INLAND TO THE UPPER 60S ALONG THE COAST
(NORMAL LOWS ARE MID TO UPPER 50S).
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...A MID-LEVEL SHORTWAVE ACROSS THE OHIO VALLEY...
EMBEDDED WITHIN NORTHWEST FLOW ALOFT...WILL MOVE ACROSS THE AREA
SAT AFTERNOON/EVE AS A BACKDOOR COLD FRONT NEARS THE AREA FROM THE
NORTH. AIRMASS WILL BE UNSTABLE WITH MIXED LAYER CAPE VALUES AROUND
2000 J/GK. MODEL SOUNDINGS SUPPORTIVE OF STRONG WINDS GUSTS AT THE
SURFACE GIVEN INVERTED-V PROFILES. HOWEVER...MID-LEVEL LAPSE RATES
ARE NOT PARTICULARLY CONDUCIVE FOR DEEP CONVECTION AND THIS SHOULD
SERVE TO LIMIT SEVERE WEATHER POTENTIAL. WILL BRING POPS UP TO GOOD
CHANCE...THUS KEEPING A SCATTERED COVERAGE. IF MODEL TRENDS
CONTINUE...COVERAGE MAY GET BUMPED UP TO NUMEROUS. COLD FRONT SHOULD
REACH THE NORTHERN ZONES DURING THE EVE AND THEN MOVE ACROSS THE
REMAINDER OF THE FORECAST AREA OVERNIGHT...SHIFTING WINDS TO THE NE.
AIRMASS SHOULD DRY OUT SUFFICIENTLY DURING SUN...ESPECIALLY BY
AFTERNOON. POPS WILL BE HELD TO SLIGHT CHANCE WITH SOUTHERNMOST
ZONES MORE INCLINED THAN NORTHERN AREAS FOR AN ISOLATED SHOWER.
HIGHS ON SAT WILL BE CONSIDERABLY ABOVE CLIMATOLOGY WITH MANY AREAS
AWAY FROM THE COAST GETTING TO NEAR 90. INLAND PROGRESSION OF
SEABREEZE...WHILE NOT PINNED TO THE COAST...SHOULD BE LIMITED
GIVEN SOUTHWEST FLOW. THIS WILL KEEP THE BEACH COMMUNITIES AND
NEARBY ENVIRONS...ESPECIALLY ACROSS BRUNSWICK AND SOUTHERN NEW
HANOVER COUNTIES...IN THE LOWER TO MID 80S. SUN WILL BE
CONSIDERABLY COOLER WITH NE WINDS SHAVING 5 TO 10 DEGREES OFF.
HIGHS WILL BE IN THE LOWER TO MID 80S WITH PERHAPS A FEW UPPER 70S
ACROSS THE CAPE FEAR REGION. COOLEST NIGHTTIME LOWS WILL OCCUR SUN
NIGHT...AROUND 60 TO NEAR 65.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...HIGH PRESSURE DRIFTS OFFSHORE DURING MONDAY
BRINGING RETURN FLOW BACK INTO THE CAROLINAS. MID LEVEL RIDGE LAGS
BEHIND HOWEVER...SO E/NE FLOW CONTINUES THROUGH THE MID PORTIONS
OF THE COLUMN ACTS AS A LIMITING FACTOR TO TEMPS...SO EXPECT A
NEAR CLIMO DAY.
SOUTHERLY FLOW PERSISTS TUESDAY...INCREASING COLUMN MOISTURE...AND
SETTING THE STAGE FOR A POTENTIALLY SIGNIFICANT QPF EVENT LATE
TUESDAY AND WEDNESDAY. DEEP SOUTHERLY FLOW HELPS RAISE PWATS TO
NEARLY 2 INCHES...OR 2 STANDARD DEVIATIONS ABOVE NORMAL. AT THE SAME
TIME...A VORT MAX EJECTS OUT OF THE MS VLY AND MOVES
OVERHEAD...WHILE A STRONGER NORTHERN STREAM S/W DRIVES A COLD FRONT
TOWARDS THE CAROLINAS...ALL OF THIS OCCURRING IN AN AIR MASS RICH IN
THETA-E. MOISTURE TRANSPORT VECTORS PEAK ACROSS THE EASTERN
CAROLINAS VERY EARLY WEDNESDAY...COINCIDENT WITH APPROACH OF UPPER
JET AND DEVELOPING SURFACE LOW NEAR OUR AREA...WHICH SUGGESTS AT
LEAST A PERIOD OF MDT/HVY CONVECTIVE RAIN. ATTM THE ECMWF IS SLOWER
AND STRONGER WITH THESE FEATURES...AND IS THE OUTLIER...BUT EVEN THE
GFS HAS AN EXTENDED PERIOD OF RAIN/TSTMS BEGINNING LATE TUESDAY AND
PERSISTING UNTIL FROPA LATE WED MORNING. CURRENT HPC QPF PROGS
SUGGEST A WIDESPREAD 1" RAINFALL EVENT...BUT IN PERSISTENT DROUGHT
HAVE DIFFICULTY BUYING SUCH A HIGH AMOUNT. WILL INCREASE POP TO HIGH
CHANCE WITH ENHANCED QPF...AND HOPE IT COMES TO FRUITION DUE TO
ONGOING RAINFALL DEFICITS. WILL UNDERCUT MEX NUMBERS DUE TO CLOUDS
AND RAIN...WITH HIGHS IN THE UPPER 70S TO LOW 80S.
COOL HIGH PRESSURE BUILDS IN BEHIND THE FRONT FOR THE END OF THE
WEEK WITH MAX AND MIN TEMPS BOTH SLIGHTLY BELOW CLIMO.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 18Z...VFR IS EXPECTED THROUGH THIS AFTERNOON. WINDS WILL BE
SOUTHWEST TO WEST AT FLO/LBT AND SSW 10-15 KT AT THE COASTAL
TERMINALS THIS AFTERNOON.
EXPECT MID TO UPPER LEVEL BKN/OVC CONVECTIVE DEBRIS CLOUDS FROM TSTM
ACTIVITY IN THE WESTERN CAROLINAS LATE THIS AFTERNOON THROUGH
TONIGHT. LOW CONFIDENCE BUT WILL INCLUDE VCTS FOR THE INLAND
TERMINALS ROUGHLY FROM 01Z-05Z DUE TO INCREASED VORTICITY/UVVS
ASSOCIATED WITH A DAMPENING UPPER S/W TROF PROGRESSING THRU THE
UPPER RIDGE. SUB-VFR CONDITIONS WILL BE POSSIBLE AT THE INLAND
TERMINALS SHOULD ANY OF THIS ACTIVITY ACTUALLY MOVE OVERHEAD. THIS
ACTIVITY SHOULD WEAKEN AS IT SPREADS TO THE COAST LATE EVENING/EARLY
MORNING.
EXTENDED OUTLOOK...SCATTERED SHOWERS AND THUNDERSTORMS
SATURDAY...AND AT THE SOUTHERN TERMINALS SUNDAY. LOW CONFIDENCE
EARLY MORNING FOG/IFR MONDAY AND TUESDAY. CHANCE SHOWERS AND
THUNDERSTORMS TUESDAY NIGHT INTO WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 430 PM FRIDAY...A MODERATE SEABREEZE CIRCULATION IS ONGOING
ACROSS THE NEARSHORE WATERS CURRENTLY...WITH WINDS BACKED AROUND TO
THE SOUTH-SOUTHWEST AT AROUND 15 KNOTS. FARTHER OFFSHORE A SOUTHWEST
WIND 10-15 KT CONTINUES. THE ONLY MAJOR CHANGE TO THE FORECAST IS TO
LOWER SEA HEIGHTS SUBSTANTIALLY FOR THIS EVENING WHERE AREA BUOYS
ARE SHOWING AVERAGE SEA HEIGHTS ONLY AROUND 2 FEET CURRENTLY.
PREVIOUS DISCUSSION FROM 130 PM FOLLOWS...
A WEAK RIDGE AXIS LOCATED ACROSS THE OFFSHORE WATERS RESULTING FROM
THE DEVELOPMENT OF A WEAK LEE TROUGH TO THE WEST IS KEEPING W TO SW
FLOW ACROSS THE COASTAL WATERS. A RESULTANT SEA BREEZE WILL ALLOW
SOME BACKING OF THE FLOW AND INCREASE IN SPEEDS THAT WILL PERSIST
INTO THE EVENING. SEAS REMAIN 2 FT ACROSS MOST OF THE COASTAL WATERS
BUT WILL INCREASE ONCE THE SOUTHWESTERLY FLOW INCREASES THIS
AFTERNOON. CHOPPY CONDITIONS TONIGHT WILL IMPROVE OVERNIGHT AS
SPEEDS DIMINISH SOME AND BEGIN TO VEER BACK TO A WESTERLY DIRECTION.
COULD SEE SOME CONVECTION OVERNIGHT...BUT MOST OF THE ACTIVITY
SHOULD OCCUR OVER THE OFFSHORE WATERS WHERE THE INSTABILITY WILL BE
GREATEST.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...WILL INITIALIZE WITH SW WINDS SAT. WINDS WILL
SHIFT TO THE N AND THEN NE WITH THE PASSAGE OF A BACKDOOR COLD FRONT
SAT NIGHT...LASTLY ACROSS THE SOUTHERN WATERS. WINDS WILL THEN
REMAIN FROM THE NE THROUGH THE REMAINDER OF THE WEEKEND. STRONGEST
WINDS THIS PERIOD WILL BE DURING A NE SURGE SUN AFTERNOON AND EVE.
WINDS MAY REACH SMALL CRAFT ADVISORY LEVELS IN GUSTS DURING THIS
TIME. HIGHEST SEAS WILL OCCUR SUN NIGHT...BUILDING FROM 3 TO 4 FT
SAT TO AS HIGH AS 4 TO 6 FT LATE SUN AND SUN NIGHT. A MARGINAL SMALL
CRAFT ADVISORY MAY BE REQUIRED LATE IN THE WEEKEND.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 3 PM FRIDAY...MODERATE NE WINDS START THE PERIOD AS HIGH
PRESSURE RIDGES DOWN THE EAST COAST. THESE WINDS...OF 10-15
KTS...WILL GRADUALLY VEER TO THE EAST...THEN SOUTH THROUGH THE
NIGHT AS HIGH DRIFTS OFFSHORE AND ALLOWS RETURN FLOW TO DEVELOP
ACROSS THE WATERS. BY TUESDAY...S/SE WINDS BEGIN TO INCREASE AS
PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING COLD
FRONT...BECOMING 10-20 KTS LATE TUESDAY NIGHT AND EARLY
WEDNESDAY...BEFORE EASING AND VEERING TO THE NW LATE WEDNESDAY
BEHIND COLD FRONT. THE SEA SPECTRUM WILL BE DOMINATED BY WIND
WAVES THROUGH THE PERIOD...NE WIND WAVES OF 4-5 FT MONDAY DROP TO
3-4 FT TUE/WED WITH A PREDOMINANT SOUTHERLY WIND WAVE. LATE
WEDNESDAY NIGHT A PERIOD OF CONFUSED SEAS WILL OCCUR BEFORE NW
WIND WAVES DEVELOP BEHIND THE FRONT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RJD
LONG TERM...JDW
AVIATION...MRR/SRP
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
314 PM CDT FRI MAY 4 2012
.SHORT TERM...
MAIN CHALLENGE WILL BE TRYING TO NARROW DOWN PCPN CHANCES OVER THE
NEXT THREE DAYS. MODELS NOT VERY CLOSE IN AGREEMENT SO WILL TRY
NOT TO STRAY TOO FAR FROM CONTINUITY FOR NOW.
TONIGHT...FA HAS REMAINED PRETTY CLOUDY AND COOL TODAY WITH STEADY
EAST WINDS. THESE DRIER EAST/NE WINDS HAVE REALLY PUT THE DAMPER
ON PCPN TODAY. THERE REALLY HAS NOT BEEN MUCH PCPN AT ALL ACROSS
THE FA THIS AFTERNOON. WHAT THERE IS HAS TAPERED OFF TO SPRINKLES
NOW. THE CLOUDS SHOULD CONTINUE TO HOLD OVER THE AREA TONIGHT AND
THESE CLOUDS WILL HELP TO HOLD UP TEMPS. SOME GUIDANCE PRODUCTS
ARE INDICATING THE POTENTIAL FOR SOME FOG TONIGHT. BETTER CHANCES
FOR FOG MAY BE ALONG AND WEST OF THE VALLEY FURTHER AWAY FROM THE
DRIER EASTERLY FLOW. WILL START OUT WITH FOG MENTIONED ACROSS THE
KDVL REGION AND LET LATER SHIFTS TAKE ANOTHER LOOK AT IT. AS FAR
AS PCPN CHANCES GO IT SEEMS THAT RIGHT NOW THE MAIN ACTION HAS
BEEN ACROSS SOUTHERN SD INTO SOUTHERN MN. REALLY NO LOW LEVEL JET
TO SPEAK OF TONIGHT BUT THE UPPER JET REMAINS OVER THE AREA WITH
SOME 850MB WARM ADVECTION. NOT REALLY INTENSE PARAMETERS BUT
ENOUGH TO KEEP SOME LOW CHANCES FOR PCPN OVER THE FA AND SLIGHTLY
BETTER ACROSS THE SOUTH.
SAT-MON...MOST OF SAT LOOKS DRY TOO. IF IT STAYS CLOUDY IT WILL
PROBABLY STAY COOL LIKE IT DID TODAY SO ENDED UP CUTTING BACK A
LITTLE ON TEMPS. IF THE AREA GETS MORE SUN THESE TEMPS WILL
PROBABLY BE A LITTLE TOO COOL. MODELS CONTINUE TO SHOW SAT NIGHT
BEING THE BEST CHANCE FOR MORE PCPN ACROSS THE AREA. BEST
INSTABILITY REMAINS SOUTH OF THE FA SO HIGHER PCPN AMOUNTS SHOULD
STAY SOUTH OF THE FA TOO. COULD BE ANOTHER EVENT LIKE TODAY WHERE
THERE IS MORE PCPN ACROSS THE SOUTH THAN THE NORTH...AND AMOUNTS
END UP BEING MUCH LESS THAN EXPECTED. EITHER WAY MODEL AGREEMENT
NOT THE BEST WITH THIS EVENT BUT THEY HAVE BEEN TRENDING SOUTH
WITH THE HEAVIEST PCPN OR ACROSS EASTERN SD INTO SOUTHERN MN. DRY
SLOT SHOULD START TO WORK INTO THE AREA ON SUN AND SUN NIGHT.
AGAIN MODELS ALL OVER THE PLACE IN REGARD TO PCPN PLACEMENT SO IT
COULD BE COMPLETELY DRY OR THERE COULD BE SOME LINGERING LIGHT
PCPN. BY MON THERE MAY BE SOME COLD POOL AFTERNOON SHOWERS WITH
BEST CHANCES ACROSS THE NORTH.
.LONG TERM (MON NIGHT THRU FRI)...
LARGE UPPER SYSTEM WILL BE MOVING ACROSS SOUTH CENTRAL CANADA AT THE
START OF THE EXTENDED PERIOD. CWFA WILL BE UNDER DEEP LAYERED
CYCLONIC FLOW AT THE START OF THE EXTENDED PERIOD WITH TEMPERATURES
JUST A BIT BELOW NORMAL. WITH THE CYCLONIC FLOW AND COLDER AIR ALOFT
COULD SEE SOME -SHRA. MODELS HAVE BEEN FLIP/FLAPPING ABOUT UPPER LOW
EARLY IN PERIOD IN REGARDS TO IT DROPPING SOUTH INTO MINNESOTA
TUESDAY. ECMWF HAS BEEN SLOWER AND DEEPER PAST 2 RUNS AND ABOUT 12
HOURS SLOWER THAN GFS/GEM/DGEX. AS LATEST RUNS IN GENERAL
AGREEMENT FEEL ALLBLENDS WILL HAVE A DECENT HANDLE INTO TUESDAY.
COULD BE PRETTY WINDY AT THE START OF THIS PERIOD WITH GOOD
DIRECTION HOOK-UP AND TIGHT GRADIENT INTO TUESDAY MORNING...
ESPECIALLY IF SLOWER ECMWF VERIFIES BETTER.
SURFACE HIGH BUILDS IN OVER THE AREA WEDNESDAY MORNING SO IT COULD
BE THE COOLEST OF THIS PERIOD...WITH LOWS WEDNESDAY MORNING IN THE
30S. AS HIGH DEPARTS UPPER RIDGE BUILDS AHEAD OF NEXT WAVE CRASHING
THE COAST. WITH PATTERN FLATTENING OUT THE SYSTEM APPEARS A BIT MORE
PROGRESSIVE THAN ONE EARLY THIS PERIOD. MODELS SUGGEST SUFFICIENT
RETURN FLOW DEVELOPS RESULTING IN WEAK INSTABILITY. 700 WAA AND LOW
LEVEL MOISTURE RETURN SHOULD BE SUFFICIENT TO GENERATE SOME TSRA
LATER ON THURSDAY. SOME LIGHT SHRA ANTICIPATED WITH FRONTAL PASSAGE
EARLY FRIDAY.
&&
.AVIATION...
EXPECT VFR THROUGH 03Z-06Z...THEN MVFR OR LOCAL IFR CIG POSSIBLE
AS BOUNDARY LAYER FORECAST TO SATURATE. HRRR DID A GOOD JOB OF
PREDICTING BREAKUP OF THIS MORNINGS IFR CIGS REDEVELOPS AREAS OF
MVFR/IFR CIGS AFT 05Z. RASH IN THE DVL AREA EXPECTED TO CONTINUE
THROUGH 00Z. RASH MOVG INTO FAR AND GFK AREAS AFT 01Z AND BJI /
TVF AFTER 06Z.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
GODON/EWENS
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
456 PM CDT FRI MAY 4 2012
.DISCUSSION...
SEE AVIATION DISCUSSION BELOW
&&
.AVIATION...
A SEVERE THUNDERSTORM WATCH IS IN AFFECT FOR THE ENTIRE AREA UNTIL
11PM CDT. A SHORT WAVE TROUGH CENTERED IN CENTRAL OKLAHOMA WITH AN
AXIS EXTENDING SOUTH SOUTHWEST THROUGH CROCKETT COUNTY IS MOVING
EAST SLOWLY. A LINE OF SHOWERS AND THUNDERSTORMS APPROXIMATELY
FIFTY TO SIXTY MILES WIDE IS CURRENTLY NORTH OF BLACKWELL TX
EXTENDS NORTHEAST TO NEAR ALBANY AND FORT GRIFFIN TX AND ABILENE...
IS ASSOCIATED WITH A WEAK DRY LINE. SOME STORMS ARE SEVERE OR WILL
BECOME SEVERE WITH GUSTY WINDS...HEAVY RAIN AND POSSIBLE HAIL.
ADDITIONAL SHOWERS ARE EXPECTED TO DEVELOP ALONG THIS LINE FARTHER
SOUTH THIS EVENING AS THE ENTIRE LINE ADVANCES EAST THROUGH THE
AREA THE NEXT 6 HOURS. NEAR THIS DEVELOPING LINE OF SHOWERS
AND THUNDERSTORMS EXPECT IFR CONDITIONS...LOCALLY HEAVY RAIN IN
THUNDERSTORMS...AND LOCALLY GUSTY SURFACE WINDS THAT MAY CAUSE
LOCAL AND BRIEF WINDY CONDITIONS AND CROSS WIND LANDING AND
TAKEOFF CONDITIONS THE NEXT 3 TO 6 HOURS. ELSEWHERE AWAY FROM THIS
SHOWER LINE MOSTLY VFR CONDITIONS WILL PREVAIL.MOSTLY VRF
CONDITIONS ARE EXPECTED TO PREVAIL ACROSS MOST OF THE AREA BY LATE
NIGHT AND INTO EARLY SATURDAY MORNING. VERY LOCALIZED PATCHY
GROUND FOG IS POSSIBLE BY EARLY MORNING IN THE VICINITY OF EVENING
RAIN AREAS.
&&
.PREV DISCUSSION... /ISSUED 354 PM CDT FRI MAY 4 2012/
SHORT TERM..
LATEST RUC SHOWING INITIATION OF CONVECTIVE ACTIVITY ASSOCIATED WITH
AN UPPER SHORT WAVE JUST WEST OF CROCKETT COUNTRY CONCOMITANT WITH
THE POSITION OF THE DRYLINE...WHERE LATEST RADAR LOOP IS ALSO
SHOWING SOME DEVELOPMENT. RUC ALSO SHOWING A DAMPENING OF THIS
FEATURE OVER THE NEXT SEVERAL HOURS. MORE PROMISING FOR LATER THIS
AFTERNOON INTO EARLY EVENING IS A DEEPENING UPPER SHORTWAVE IN THE
VICINITY OF A TIGHTENING DRYLINE OVER THE EASTERN BIG COUNTRY SOUTH
INTO THE HEARTLAND... WHERE THE BEST CHANCE OF CONVECTION WOULD
RESIDE. DRYLINE WILL RETREAT THROUGH THE LATE EVENING HOURS WITH
RAINFALL ENDING OVER THE CWA AFTER MIDNIGHT.
LOOKING FOR A WARMER DAY TOMORROW WITH 100 PLUS TEMPS OVER THE BIG
COUNTRY AND THE WESTERN CONCHO VALLEY. UPPER RIDGING OVER THE
FORECAST AREA TOMORROW WILL BE UNDERCUT BY A SHORTWAVE MOVING OVER
THE SOUTHERN CWA BY LATE TOMORROW AFTERNOON...WITH THE BEST CHANCE
OF CONVECTIVE ACTIVITY...PER THE LATEST NAM...OVER OUR SOUTHEASTERN
COUNTIES.
LONG TERM...
LOW CONFIDENCE FORECAST FOR MUCH OF THE EXTENDED PERIOD. DRYLINE
WILL RETREAT WESTWARD SATURDAY EVENING WITH A FEW STORMS POSSIBLE
DURING THE EVENING HOURS. ONE LAST DAY OF TEMPERATURES IN THE 90S
ON SUNDAY...AS COOLER TEMPERATURES ARE ON THE WAY FOR NEXT WEEK
WITH HIGHS MAINLY IN THE 80S MONDAY THROUGH FRIDAY. CONSIDERABLE
MODEL DIFFERENCES EXIST WITH THE SOUTHWARD PROGRESSION OF THE COLD
FRONT SUNDAY NIGHT INTO MONDAY. THE NAM IS THE FASTEST MODEL AND
BRINGS THE FRONT INTO THE NORTHERN BIG COUNTRY LATE SUNDAY AFTERNOON
WHILE THE GFS IS ABOUT 12 HOURS SLOWER. DECIDED TO SPLIT THE
DIFFERENCE BETWEEN THE TWO BUT LEAN A BIT MORE IN FAVOR WITH THE
NAM AND BRING THE FRONT ACROSS THE AREA DURING THE OVERNIGHT
HOURS. KEPT SLIGHT POPS GOING SUNDAY NIGHT AND AGAIN ON MONDAY
WITH THE PASSAGE OF THE FRONT.
THE FRONT IS EXPECTED TO STALL JUST SOUTH OF THE AREA THROUGH MID
WEEK BEFORE WASHING OUT. MEDIUM RANGE MODELS CONTINUE TO SHOW A
CLOSED UPPER LOW DEVELOPING OVER THE DESERT SOUTHWEST/BAHA REGION
EARLY NEXT WEEK...THEN TRACKING EAST TOWARDS WEST TEXAS BY MID
WEEK. GFS REMAINS VERY WET WITH THIS SCENARIO BUT CONFIDENCE
CONTINUES TO BE LOW CONCERNING PRECIPITATION CHANCES NEXT WEEK.
THE FORECAST WILL CONTINUE TO ADVERTISE SLIGHT PRECIPITATION CHANCES
FOR MUCH OF NEXT WEEK...PENDING HIGHER CONFIDENCE IN THE MODELS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 97 72 100 71 93 / 20 20 10 10 10
SAN ANGELO 100 70 100 70 94 / 20 20 10 20 10
JUNCTION 95 71 97 70 93 / 10 20 10 20 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/99/99
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
354 PM CDT FRI MAY 4 2012
.SHORT TERM..
LATEST RUC SHOWING INITIATION OF CONVECTIVE ACTIVITY ASSOCIATED WITH
AN UPPER SHORT WAVE JUST WEST OF CROCKETT COUNTRY CONCOMITANT WITH
THE POSITION OF THE DRYLINE...WHERE LATEST RADAR LOOP IS ALSO
SHOWING SOME DEVELOPMENT. RUC ALSO SHOWING A DAMPENING OF THIS
FEATURE OVER THE NEXT SEVERAL HOURS. MORE PROMISING FOR LATER THIS
AFTERNOON INTO EARLY EVENING IS A DEEPENING UPPER SHORTWAVE IN THE
VICINITY OF A TIGHTENING DRYLINE OVER THE EASTERN BIG COUNTRY SOUTH
INTO THE HEARTLAND... WHERE THE BEST CHANCE OF CONVECTION WOULD
RESIDE. DRYLINE WILL RETREAT THROUGH THE LATE EVENING HOURS WITH
RAINFALL ENDING OVER THE CWA AFTER MIDNIGHT.
LOOKING FOR A WARMER DAY TOMORROW WITH 100 PLUS TEMPS OVER THE BIG
COUNTRY AND THE WESTERN CONCHO VALLEY. UPPER RIDGING OVER THE
FORECAST AREA TOMORROW WILL BE UNDERCUT BY A SHORTWAVE MOVING OVER
THE SOUTHERN CWA BY LATE TOMORROW AFTERNOON...WITH THE BEST CHANCE
OF CONVECTIVE ACTIVITY...PER THE LATEST NAM...OVER OUR SOUTHEASTERN
COUNTIES.
&&
.LONG TERM...
LOW CONFIDENCE FORECAST FOR MUCH OF THE EXTENDED PERIOD. DRYLINE
WILL RETREAT WESTWARD SATURDAY EVENING WITH A FEW STORMS POSSIBLE
DURING THE EVENING HOURS. ONE LAST DAY OF TEMPERATURES IN THE 90S
ON SUNDAY...AS COOLER TEMPERATURES ARE ON THE WAY FOR NEXT WEEK
WITH HIGHS MAINLY IN THE 80S MONDAY THROUGH FRIDAY. CONSIDERABLE
MODEL DIFFERENCES EXIST WITH THE SOUTHWARD PROGRESSION OF THE COLD
FRONT SUNDAY NIGHT INTO MONDAY. THE NAM IS THE FASTEST MODEL AND
BRINGS THE FRONT INTO THE NORTHERN BIG COUNTRY LATE SUNDAY AFTERNOON
WHILE THE GFS IS ABOUT 12 HOURS SLOWER. DECIDED TO SPLIT THE
DIFFERENCE BETWEEN THE TWO BUT LEAN A BIT MORE IN FAVOR WITH THE
NAM AND BRING THE FRONT ACROSS THE AREA DURING THE OVERNIGHT
HOURS. KEPT SLIGHT POPS GOING SUNDAY NIGHT AND AGAIN ON MONDAY
WITH THE PASSAGE OF THE FRONT.
THE FRONT IS EXPECTED TO STALL JUST SOUTH OF THE AREA THROUGH MID
WEEK BEFORE WASHING OUT. MEDIUM RANGE MODELS CONTINUE TO SHOW A
CLOSED UPPER LOW DEVELOPING OVER THE DESERT SOUTHWEST/BAHA REGION
EARLY NEXT WEEK...THEN TRACKING EAST TOWARDS WEST TEXAS BY MID
WEEK. GFS REMAINS VERY WET WITH THIS SCENARIO BUT CONFIDENCE
CONTINUES TO BE LOW CONCERNING PRECIPITATION CHANCES NEXT WEEK.
THE FORECAST WILL CONTINUE TO ADVERTISE SLIGHT PRECIPITATION CHANCES
FOR MUCH OF NEXT WEEK...PENDING HIGHER CONFIDENCE IN THE MODELS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 97 72 100 71 93 / 20 20 10 20 10
SAN ANGELO 100 70 100 70 94 / 20 20 10 20 10
JUNCTION 95 71 97 70 93 / 10 20 10 20 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
15/24
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
229 PM CDT FRI MAY 4 2012
.SHORT TERM...TONIGHT AND SATURDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LAST NIGHTS
COLD FRONT DRIFTING SOUTH OVER NORTHERN ILLINOIS/INDIANA WHILE
HUDSON BAY HIGH PRESSURE IS BUILDING SOUTHWARD INTO THE WESTERN
GREAT LAKES. LOW CLOUDS HAVE STUCK AROUND ALL DAY OVER CENTRAL
WISCONSIN WHERE MOISTURE REMAINS PLENTIFUL...BUT NORTHERN WISCONSIN
HAS CLEARED OUT NICELY. LOOKING UPSTREAM...SHORTWAVE TROUGH OVER
SOUTH-CENTRAL CANADA HAS HELPED RETURN FLOW KICK OFF SHOWERS AND
THUNDERSTORMS OVER WESTERN MINNESOTA AND EASTERN SOUTH DAKOTA.
THESE STORMS HAVE BEEN RIDING ALONG THE MOST UNSTABLE CAPE
GRADIENT...WHICH STRETCHES FROM SOUTHERN MINNESOTA INTO SW
WISCONSIN. AS THE RETURN FLOW SHIFTS EAST TONIGHT...SHOWER AND
THUNDERSTORM CHANCES ARE THE MAIN FORECAST CONCERN.
TONIGHT...WEAK SHORTWAVE ACTIVITY WILL CLIMB OVER TOP THE MID-LEVEL
RIDGE INTO FAR SOUTH-CENTRAL CANADA TONIGHT. RETURN FLOW OVER THE
NORTHERN PLAINS WILL MOVE EAST INTO WESTERN WISCONSIN BY 06Z AND
CENTRAL WISCONSIN BY 12Z. CLUSTER OF SHOWERS AND STORMS WILL SPREAD
EAST WITH THE ISENTROPIC ASCENT ON THE 300-305K SURFACES IN A REGION
OF GOOD MOISTURE ADVECTION. HAVE NOT SEEN ANY SIGNS YET THAT THE
DRY AIR ON MPX/S SOUNDING IS ERODING THIS CLUSTER OF STORMS...SO THE
LATEST TIMING WOULD HAVE PRECIP ARRIVING LATE IN THE EVENING INTO
CENTRAL WISCONSIN. WILL INCREASE POPS AND BRING THEM FARTHER SOUTH. LIKE
THE PREVIOUS SHIFT...COULDNT FIND MUCH INSTABILITY...BUT CANT ARGUE
WITH THE CURRENT THUNDERSTORM ACTIVITY ONGOING...SO WILL ADD TO THE
FORECAST AS WELL. PRECIP WILL SPREAD EAST OVERNIGHT...BUT WILL
ENCOUNTER DRIER AIR OVER THE NORTH-CENTRAL GREAT LAKES...WHICH AM
COUNTING ON TO FINALLY SLOW ITS FORWARD PROGRESSION. SO WILL KEEP
THE LOWEST CHANCES OVER THE EAST. LOWS MAINLY IN THE 40S.
SATURDAY...300-305K ISENTROPIC ASCENT WILL CONTINUE TO SPREAD EAST
DURING THE MORNING...WHILE THE 850MB BAROCLINIC ZONE STALLS OVER
NORTHEAST WISCONSIN. FORCING LOOKS THE BEST DURING THE MORNING WHEN
WILL HAVE THE HIGHEST CHANCES OF POPS. IN THE AFTERNOON...WE LOSE
SOME OF THE LOWER CONDENSATION PRESSURE DEFICITS AND DRIER AIR
ARRIVES IN THE MID AND UPPER LEVELS. SEEMS REASONABLE TO THINK THAT
MOST OF THE PRECIP WILL FALL DURING THE MORNING AND ONLY SPOTTY
SHOWERS OR MAYBE EVEN DRIZZLE LEFT FOR THE AFTERNOON. PLENTY OF
SATURATION BELOW 800MB...SO HAVE A TOUGH TIME SEEING CLEARING
OCCURRING. LOTS OF CLOUDS...PRECIP...AND AN EAST WIND DOES NOT BODE
WELL FOR WARM TEMPS TOMORROW. WILL MAYBE DROP THE PREV SHIFT/S
TEMPS BY A DEGREE IN SPOTS.
.LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY. SATURDAY NIGHT
INTO SUNDAY NIGHT WILL BE DOMINATED BY THE UPPER DIFFLUENCE
REGION AHEAD OF A DEEPENING UPPER LOW DRIFTING OVER THE NORTHERN
PLAINS. A SURFACE TROUGH IS PROGGED TO TRACK OVER THE WESTERN
GREAT LAKES REGION WITH RESPECT TO THIS SYSTEM. TWO SURFACE LOWS
PRESSURE REGIONS OF NOTE...ONE NEAR THE UPPER LOW OVER THE
NORTHERN PLAINS AND A SECOND NEAR THE MORE UNSTABLE AND DEEPER
MOISTURE REGION OVER THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY
REGION. THIS SOURCE OF MOIST UNSTABLE AIR IN THE RETURN FLOW IS
THE FOCUS OF POTENTIALLY ANOTHER ROUND OF HEAVY RAIN FALL FOR
SOMEWHERE IN THE STATE. AT THIS TIME BEST AMOUNTS COULD BE OVER
NORTHERN OR NORTHEAST THIRD OF THE STATE WHERE THE H8 BAROCLINIC
ZONE EXTENDS DURING THE PERIOD. NORTHERN WISCONSIN IS ALSO CLOSER
TO THE UPPER JET DYNAMICS. WHEREAS THE AIR MASS A LITTLE MORE
UNSTABLE TOWARD SOUTHERN WISCONSIN. GOING FORECAST OF THE EVENT
LOOKS GOOD...AND ANTICIPATE ONLY MINOR CHANGES WITH RESPECT TO
TIMING. 12Z RUNS INDICATED THE GFS IS MUCH SLOWER WITH DEPARTING
THE SOUTHERN STREAM SURFACE LOW ON MONDAY.
WHILE A DIMINISHED PCPN TREND IS EXPECTED LATER MONDAY INTO MONDAY
NIGHT AS THE SURFACE FRONTAL SYSTEM SHIFTS EAST AND HIGH PRESSURE
SLIDES INTO THE CENTRAL PLAINS...THE UPPER LOW IS PROGGED TO PIVOT
OVER THE GREAT LAKES REGION ON TUESDAY FOR A PERIOD OF CLOUDS AND
PERHAPS DIURNAL TYPE PCPN.
MEDIUM RAIN PROGS BUILD A SURFACE AND UPPER RIDGE INTO THE AREA
FOR MID WEEK BEFORE THE NEXT NORTHERN STREAM SYSTEM APPROACHES
FROM THE NORTHERN PLAINS.
&&
.AVIATION...VFR CONDITIONS OVER NORTHERN WISCONSIN THROUGH MUCH OF
THIS EVENING. AREAS OF MVFR STRATUS OVER CENTRAL WISCONSIN WILL
GRADUALLY LIFT TO VFR WITH BREAKS IN THE CLOUDS ENLARGING THROUGH
THE AFTERNOON. NEXT AREA OF SHOWERS AND THUNDERSTORMS OVER
MINNESOTA WILL PUSH ACROSS THE TAF SITES EARLY OVERNIGHT THROUGH
TOMORROW MORNING. DRY AIR WILL IMPEDE ITS PROGRESS SOMEWHAT...SO
HAVE A SLOWER TIMING INTO EASTERN WISCONSIN. DIDNT INCLUDE THUNDER
AT THIS TIME...BUT PLENTY OF THUNDER OVER EASTERN SD...SO THAT MAY
NEED TO BE UPDATED LATER. AS THE RAIN ARRIVES LATE...EXPECT CIGS TO
FALL TO LOW END MVFR TO HIGH END IFR OVER CENTRAL AND NORTH-CENTRAL
WISCONSIN. DO NOT EXPECT MUCH IMPROVEMENT IN CONDITIONS THROUGH
MIDDAY TOMORROW AS SCATTERED SHOWERS WILL REMAIN PRESENT.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/TDH