Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 140812
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
312 AM CDT SUN SEP 14 2014

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 312 AM CDT SUN SEP 14 2014

TIMING/LOCATION OF PCPN TO BE THE MAIN FCST CHALLENGE AS TWO
DIFFERENT AREAS TO BE SUSCEPTIBLE TO LIGHT SHWR ACTIVITY. TEMPS TO
REMAIN BELOW NORMAL...JUST NOT AS COOL AS PREVIOUS DAYS.

THE 07Z MSAS SFC ANALYSIS SHOWED AN AREA OF HI PRES STRETCHED FROM
THE MID-MS VALLEY TO THE ERN GREAT LAKES. A WEAK AREA OF LOW PRES
WAS SITUATED OVER SE MANITOBA WITH A CDFNT EXTENDED S-SW THRU THE
NRN/CNTRL PLAINS. IN BETWEEN THESE SYSTEMS...THE PRES GRADIENT WAS
BEGINNING TO TIGHTEN UP OVER THE MIDWEST/WRN GREAT LAKES. SATL
IMAGERY SHOWED PLENTY OF CLOUDS COVERED NE WI WITH THE RADAR
MOSAIC PICKING UP SOME LIGHT RAIN SHWRS OVER NE MN.

MDLS ARE CONSISTENT IN SENDING A SHORTWAVE TROF INTO SRN ONTARIO/
NRN GREAT LAKES REGION TODAY. THIS UPR TROF TO ALSO PULL THE CDFNT
EWD...REACHING A CNTRL ONTARIO/N-CNTRL WI/SRN MN LINE BY 00Z MON.
BETTER DYNAMICS REMAIN IN THE VICINITY OF THE SHORTWAVE TROF AND
WITH THE ATMOSPHERE STILL QUITE DRY...HARD TO SEE MUCH PCPN OVER
NE WI. HAVE KEPT A MINIMAL POP ACROSS NRN WI FOR TODAY WITH ANY
SHWR ACTIVITY ON THE LIGHT SIDE. CLOUDS WL THICKEN UP DURING THE
COURSE OF THE DAY...BUT A SW WIND WL HELP BOOST TEMPS INTO THE LWR
TO MID 60S OVER MUCH OF THE FCST AREA. INCREASING SW WINDS MAY
BECOME STRONG ENUF THIS AFTERNOON TO MAINTAIN THE SMALL CRAFT ADVY
CURRENTLY IN EFFECT.

AS THE CDFNT SLOWLY SAGS SE THRU WI TNGT...ANOTHER SHORTWAVE TROF
IS FCST TO DIG SE THRU THE NRN PLAINS ACCOMPANIED BY A 100 KT JET
MOVING INTO THE GREAT LAKES. BETWEEN THE LIFT FROM THE CDFNT...
INCREASING Q-G/FRONTOGENETICAL FORCING AND UPR JET SUPPORT...EXPECT
TO SEE A BAND OF SHWRS TO DEVELOP OVER ROUGHLY THE SRN HALF OF WI.
PREVIOUS SHIFT ALREADY HAD ALL OF THIS TAKEN INTO ACCOUNT AND THE
ONLY CHANGE WAS TO LIFT THE SLGT CHC POPS NORTH A TIER OF COUNTIES.
MIN TEMPS TO RANGE FROM 35-40 DEGS NORTH WHERE DRY CONDITIONS TO
PREVAIL...TO THE MID TO UPR 40S SOUTH UNDER THICKER CLOUDS/CHC POPS.

THIS SHORTWAVE TROF IS PROGGED TO RACE EAST INTO THE WRN GREAT LAKES
MON MORNING AND ALREADY BE HEADED TOWARD THE ERN GREAT LAKES BY LATE
MON AFTERNOON. STRONG PV ADVECTION/Q-G FORCING IN THE MID-LEVELS
TO MOVE ACROSS SRN WI/NRN IL MON MORNING AND SHIFT EAST INTO SRN LWR
MI/NRN INDIANA MON AFTERNOON. CNTRL AND E-CNTRL WI TO RESIDE ON THE
NRN EDGE OF THE MAIN RAIN BAND...THUS HIGHEST POPS PLACED FROM Y50-
MTW WITH DECREASING POPS TO SLGT CHC FROM AUW-SUE. NRN WI TO MISS
OUT COMPLETELY ON THIS SECONDARY AREA OF RAINFALL ON MON. MAX TEMPS
TO RANGE FROM THE UPR 50S TO LWR 60S NORTH...LWR TO MID 60S SOUTH.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 312 AM CDT SUN SEP 14 2014

SURFACE HIGH PRESSURE MOVING IN BEHIND A DEPARTING COLD
FRONT...ALONG WITH AN APPROACHING UPPER LEVEL RIDGE...WILL HELP TO
KEEP THE AREA RAIN-FREE FOR MUCH OF THE WEEK. THERE IS A BACKDOOR
COLD FRONT AND SOME WEAK SHORT WAVE ENERGY THAT IS EXPECTED TO
IMPACT LOCATIONS MAINLY TO THE NORTH AND EAST OF WISCONSIN TUESDAY
INTO WEDNESDAY. IT IS POSSIBLE THAT SOME MENTION OF SHOWERS MAY
NEED TO BE ADDED AT A LATER TIME...BUT HAVE KEPT GRIDS FOR THOSE
DAYS DRY.

UPPER FLOW IS FORECAST TO BECOME MORE ZONAL DURING THE LATTER HALF
OF THE WEEK...AND AN APPROACHING TROUGH AND COLD FRONT WILL BRING
CHANCES FOR SHOWERS AND THUNDERSTORMS BACK TO THE AREA BY THE END
OF THE WEEK. TIMING THE ONSET OF RAIN WAS NOT CONSISTENT AMONG THE
MODELS SO CONFIDENCE IN THE TIMING IS NOT PARTICULARLY GOOD. HAVE
INCLUDED A CHANCE OF SHOWERS AND STORMS IN NORTH CENTRAL WISCONSIN
ON FRIDAY...WITH THUNDERSTORM CHANCES SPREADING ACROSS THE REST OF
THE AREA BY SATURDAY. HOPEFULLY LATER MODEL RUNS WILL COME INTO
BETTER AGREEMENT.

TEMPERATURES SHOULD BE A BIT BELOW NORMAL FOR MUCH OF THE
PERIOD...BUT A WARMING TREND IS LIKELY FOR THE END OF THE WEEK.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1033 PM CDT SAT SEP 13 2014

SCT-BKN VFR CLOUDS FROM 5000 TO 7000 FEET WILL CONTINUE TONIGHT
INTO SUNDAY. A WEAK FRONT SLIDING OVER THE AREA ON SUNDAY
AFTERNOON AND EVENING MAY GENERATE A FEW LIGHT SHOWERS OVER MAINLY
NORTHERN WISCONSIN.
&&

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

$$

SHORT TERM.....KALLAS
LONG TERM......MG
AVIATION.......TDH






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