Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 241107
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
607 AM CDT FRI JUL 24 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 346 AM CDT FRI JUL 24 2015

CONVECTION IN MINNESOTA AT 09Z FORECAST BY MODELS TO WEAKEN AS IT
MOVES EAST INTO CENTRAL WISCONSIN BETWEEN 12Z AND 15Z. THIS IS
REASONABLE AS IT IS MOVING INTO A WEAK UPPER RIDGE...THE LOW LEVEL
JET IS WEAKENING AND SATELLITE PICTURES SHOW WARMING TOPS.
ASSUMING THIS IS CORRECT IT SHOULD REMAIN DRY IN THE EASTERN PART
OF THE FORECAST AREA UNTIL TONIGHT. ADDITIONAL CONVECTION MAY
START AGAIN LATE THIS AFTERNOON IN CENTRAL AND NORTHCENTRAL
WISCONSIN AS THE FRONT APPROACHES. FORECAST SOUNDINGS SUGGEST THAT
THERE COULD BE SOME STRONG OR SEVERE STORMS IF THE INVERSION
BETWEEN 700 AND 800 MB CAN BE BROKEN. HIGHS TODAY SHOULD BE CLOSE
TO WHAT WE HAD YESTERDAY WITH DEWPOINTS SEVERAL DEGREES HIGHER
MAKING IT FEEL HOTTER THAN IT ACTUALLY IS.

THE WEAK COLD FRONT WILL MOVE ACROSS THE AREA TONIGHT WITH A
SCATTERED TO BROKEN LINE OF SHOWERS AND THUNDERSTORMS. CLOUDS
WILL CLEAR LATE TONIGHT AND WILL HOLD UP LOW TEMPERATURES 5 TO 10
DEGREES HIGHER THAN USUAL.

SATURDAY SHOULD BE MOSTLY SUNNY AND VERY WARM. DEWPOINTS IN THE
MIDDLE 50S TO LOW 60S SHOULD MAKE IT MORE COMFORTABLE EVEN THOUGH
HIGH TEMPERATURES WILL BE 5 DEGREES OR SO ABOVE USUAL.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 346 AM CDT FRI JUL 24 2015

MODEST UPPER-LEVEL RIDGING OVER THE CNTRL CONUS IS EXPECTED TO
SHIFT EAST A BIT TOWARD THE GREAT LAKES IN RESPONSE TO A STRONG
SHORTWAVE TROF HEADED FROM THE PACIFIC NW TOWARD THE NRN PLAINS
EARLY IN THE WEEK. THIS UPR TROF WL SHIFT EAST ALONG THE NRN TIER
OF STATES AND EVENTUALL SQUASH THE UPR RDG OVER THE GREAT LAKES BY
MID-WEEK. EVENTUALLY...THE UPR RDG RETROGRADES TOWARD THE WRN
CONUS...PLACING A W-NW FLOW INTO WI. THERE WL BE SEVERAL
OPPORTUNITIES FOR PCPN EARLY NEXT WEEK WITH A WRMFNT (MON) AND A
CDFNT (TUE/WED). TEMPS ARE EXPECTED TO REMAIN ABOVE NORMAL THRU
THE EXTENDED PERIOD.

HI PRES WL DRIFT ACROSS THE GREAT LAKES SAT NGT...BRINGING MOSTLY
CLEAR SKIES WITH LIGHT WINDS AND SLIGHTLY DRIER AIR. DEPENDING ON
HOW MUCH PCPN FALLS FRI NGT...THERE MAY BE SOME PATCHY FOG
DEVELOPING LATE AT NGT. MIN TEMPS TO RANGE FROM THE MID TO UPR 50S
NORTH...LWR TO MID 60S SOUTH. A WEAK SHORTWAVE TROF...WITH AN
EMBEDDED SHORTWAVE...IS FCST TO MOVE E-SE FROM THE UPR MS VALLEY
TOWARD SRN SECTIONS OF WI/NRN IL ON SUNDAY. THERE CONTS TO BE SOME
UNCERTAINTY ASSOCIATED WITH THIS LITTLE SYSTEM RANGING FROM
MOVEMENT TO INTENSITY TO QPF POTENTIAL. CNTRL WI APPEARS TO BE
"MOST SUSCEPTIBLE" TO ANY SHWRS/TSTMS AND PREFER TO LIMIT ANY POPS
TO THIS LOCATION FOR NOW. MAX TEMPS WL CONT TO BE WARM WITH
READINGS RANGING FROM THE LWR 80S NEAR LAKE MI...LWR TO MID 80S
NORTH AND MID TO UPR 80S SOUTH.

THIS SYSTEM EXITS THE AREA SUNDAY EVENING...HOWEVER THIS DOES NOT
END THE PCPN THREAT AS SOME OF THE MODELS BEGIN TO SEND A WRMFNT
NORTH TOWARD WI. MAY LEAVE A TOKEN POP ACROSS PARTS OF CNTRL AND
E-CNTRL WI SUNDAY NIGHT...BUT CONFIDENCE IS RATHER LOW SINCE THIS
WRMFNT COULD JUST AS EASY REMAIN WELL TO OUR SOUTH OVER CNTRL
SECITONS OF IL/IN. MIN TEMPS TO GENERALLY END UP IN THE 60-65 DEG
RANGE. THE LOCATION OF THE WRMFNT WL ALSO INFLUENCE THE WEATHER
OVER WI INTO MON...WHETHER THE FNT IS IN WI (GFS) OR STILL
RELEGATED WELL TO OUR SOUTH (ECMWF/GEM). JUST LIKE SUNDAY NGT...
CANNOT COMPLETELY RULE OUT THE GFS AS THE UPR RDG WL POKE INTO THE
GREAT LAKES AT THIS TIME AND COULD LIFT THE FNT NWD. THEREFORE...
WL KEEP A SMALL POP IN THE FCST FOR NOW...BUT ALSO WOULD NOT BE
SURPRISED TO SEE SUNDAY NGT AND MON REMAIN DRY. ONE THING THAT
DOES APPEAR CERTAIN IS THE CONTINUATION OF THE ABOVE NORMAL TEMPS
(MORE MID TO UPR 80S)..EXCEPT COOLER NEAR LAKE MI.

THE MAIN WEATHER FEATURE OF INTEREST DURING THE MON NGT THRU TUE
NGT TIME FRAME WL BE THE MOVEMENT/INTENSITY OF A STRONG SHORTWAVE
TROF PRECEDED BY A CDFNT. THIS UPR TROF IS PROGGED TO MOVE ACROSS
SRN CANADA/NRN TIER OF STATES AND HELP SHOVE THE CDFNT INTO THE
GREAT LAKES LATE TUE NGT. WOULD EXPECT THE WRMFNT TO ACTUALLY LIFT
NWD INTO WI ON TUE BRINGING A CHC OF SHWRS/TSTMS TO NE WI...
FOLLOWED BY ADDITIONAL SHWRS/TSTMS TUE NGT WITH THE CDFNT. IF
THERE IS ANY SVR POTENTIAL...IT WOULD BE TUE NGT WITH CAPES STILL
AROUND 1500 J/KG AND BULK SHEAR VALUES IN THE 30-40KT RANGE. HAVE
PLACED THE HIGHEST POPS OVER THE FCST AREA FOR TUE NGT.

THERE COULD BE A LINGERING SHWR OVER E-CNTRL WI INTO WED
MORNING...BUT AN INFLUX OF DRIER AIR ON THE SRN FLANK OF THE UPR
TROF PUSHING ALONG THE U.S.-CANADIAN BORDER...SHOULD BRING
IMPROVING CONDITIONS TO THE REGION. WEAK HI PRES TO OUR WEST AND
SOUTH THRU MID-WEEK WOULD KEEP DRY WEATHER IN THE FCST THRU THU.
SLIGHTLY COOLER AIR ALOFT TO FILTER INTO WI AT MID-WEEK WITH
READINGS ONLY A COUPLE DEGREES ABOVE NORMAL.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 606 AM CDT FRI JUL 24 2015

AN AREA OF SHOWERS AND THUNDERSTORMS WILL BE MOVING
INTO CENTRAL AND NORTHCENTRAL WISCONSIN BETWEEN 13Z AND 14Z.
CURRENT THINKING IS THAT THEY WILL WEAKEN OR DISSIPATE BY 17Z
BEFORE REACHING EASTERN WISCONSIN. ANOTHER ROUND OF THUNDERSTORMS
IS EXPECTED TO FORM DURING THE LATE AFTERNOON IN CENTRAL AND
NORTHCENTRAL WISCONSIN AHEAD OF A WEAK COLD FRONT. THAT ACTIVITY
SHOULD MOVE ACROSS THE ENTIRE AREA DURING THE EVENING HOURS.

VFR WEATHER IS EXPECTED OUTSIDE OF ANY SHOWER OR THUNDERSTORM
ACTIVITY TODAY. AN PERIOD OF MVFR OR IFR CONDITIONS ARE LIKELY
LATER TONIGHT WITH CLEARING AND VFR CONDITIONS SATURDAY.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......RDM


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