Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 302030
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
330 PM CDT SAT AUG 30 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SYNOPSIS...
ISSUED AT 233 PM CDT SAT AUG 30 2014

WARM AND RATHER HUMID WEATHER WILL SHOWERS AND THUNDERSTORMS AT
TIMES THROUGH THE MIDDLE OF NEXT WEEK.

PRETTY TYPICAL LATE SUMMER UPPER LEVEL PATTERN IN PLACE ACRS
NOAM. BROAD BAND OF WESTERLIES WAS ACRS THE NRN CONUS AND SRN
CANADA. THOSE WL STRENGTHEN FURTHER AND SAG SWD DURING THE EARLY
PART OF THE FCST PERIOD...THEN WEAKEN AND RECEDE NWD DURING THE
LATTER HALF OF THE PERIOD. A SERIES OF SHRTWVS PROGRESSING THROUGH
THE PATTERN WL INTERACT WITH FRONTAL BOUNDARY EXPECTED TO REMAIN
STETCHED OUT W-E ALONG THE SRN EDGE OF THE MAIN WESTERLIES...
BRINGING SEVERAL OPPORTUNITIES FOR PCPN TO THE FCST AREA.

TEMPS ARE EXPECTED TO REMAIN AOA NORMAL FOR MUCH OF THE FCST
PERIOD BEFORE DROPPING BACK CLOSE TO NORMAL LATE. IT WILL ALSO BE
HUMID AT TIMES. THE PATTERN LOOKS FAVORABLE FOR ABV NORMAL PCPN
AMNTS...THOUGH TIMING OF THE PCPN BECOMES MORE DIFFICULT AFTER
THE FIRST COUPLE DAYS OF THE FCST.
&&

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 233 PM CDT SAT AUG 30 2014

SEVERAL CONCERNS TO DEAL WITH...MAINLY DURING THE TNGT PART OF THE
FCST. THESE CONCERNS INCLUDE: WHEN TO END THE PCPN CHCS...HOW MUCH
FOG WL DEVELOP AND MIN TEMPS.

THE 19Z MSAS SFC ANALYSIS INDICATED AN AREA OF LOW PRES JUST SOUTH
OF ESC WITH A CDFNT STRETCHED SWD ALONG THE WRN SHORES OF LAKE MI
AND A SECONDARY TROF EXTENDED W-SW THRU SW WI. FARTHER WEST...A
RDG OF HI PRES STRETCHED FROM WRN ONTARIO SWD TO THE CNTRL PLAINS.
VSBL SATL IMAGERY SHOWED A PLETHORA OF CLOUDS OVER WI ROTATING
AROUND A SHORTWAVE TROF IN THE MID-LEVELS OF THE ATMOSPHERE. LOCAL
RADAR MOSAIC PICKED UP SEVERAL BANDS OF LIGHT TO MODERATE SHWRS
OVER THE ERN THREE-QUARTERS OF WI WITH A STEADY E-NE MOVEMENT.

THE TRAILING SHORTWAVE TROF/EMBEDDED SHORTWAVE TO STILL CROSS WI
THIS EVENING AND MAY HAVE TO LINGER A POP AT LEAST OVER ERN
SECTIONS OF THE FCST AREA WHERE DEW POINTS ARE STILL RELATIVELY
HIGH. ONCE THESE FEATURES DEPART OVRNGT...WEAK RIDGING BOTH AT THE
SFC AND ALOFT TO MOVE INTO THE WRN GREAT LAKES. WEAK SUBSIDENCE
AND MODEST DRYING COULD BRIEFT BREAK THE CLOUD COVER UP...HOWEVER
THIS WOULD LEAD TO FOG DEVELOPMENT ESPECIALLY AFTER ALL THE RAIN
WE HAVE SEEN OVER THE PAST 36 HOURS. EXPECT FOG TO DEVELOP AROUND
THE MIDNGT HOUR AND COULD BECOME QUITE THICK TOWARD DAYBREAK
MAINLY ACROSS NRN AND CNTRL WI WHERE THE HIGHER RAINFALL TOTALS
OCCURRED. NO HEADLINES YET...BUT LATER SHIFTS WL HAVE TO WATCH
THIS CLOSELY. MIN TEMPS TO RANGE FROM THE UPR 40S TO LWR 50S
NORTH...MID TO UPR 50S SOUTH.

THE FOG WL BURN OFF BY MID-MORNING...LEAVING SOME SUNSHINE FOR
SUNDAY AS THE RIDGING SHIFTS OFF TO THE EAST. DO EXPECT TO SEE
MID/HI CLOUDS BEGIN TO APPROACH CNTRL WI SUNDAY AFTERNOON AHEAD OF
AN IMPRESSIVE LOOKING SYSTEM MOVING INTO THE UPR MS VALLEY. LOOK
FOR MAX TEMPS TO RANGE FROM THE MID TO UPR 70S NORTH...AROUND 80
DEGS SOUTH (COOLER NEAR LAKE MI).

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 233 PM CDT SAT AUG 30 2014

SHRTWV PROGRESSING EWD FM THE NRN PLAINS WL GENERATE CYCLONE OVER
THE UPPER MIDWEST DURING THE LATTER PART OF THE LABOR DAY
WEEKEND. THE NAM SEEMED WAY OVERDONE WITH THE STRENGTH OF THE
CYCLONE AND WAS DISCOUNTED. THE MOST LIKELY SCENARIO SEEMS TO BE
FOR SVR STORMS TO FIRE OUT TO THE WEST SUN AFTN/EVENING...THEN
MOVE EAST. THEY SHOULD BE WEAKENING BEFORE THEY ARRIVE IN THE
AREA...THOUGH CAN/T RULE OUT SVR WINDS/HAIL SUN NGT...ESP AS LLJ
GETS DIRECTED INTO THE WRN PART OF THE FCST AREA LATE SUN NGT. THE
STORMS WL LIKELY STILL BE ACRS THE AREA MON MORNING...THEN THE
QUESTION IS WHETHER OR NOT THEY EXIT QUICKLY ENOUGH TO ALLOW FOR
ANOTHER ROUND OF STORMS MON AFTN/EVE. THE ECMWF IS A DEFINITE NO-
VOTE. IT/S SLOWER ARRIVAL OF THE LEAD CONVECTION AND FASTER
ARRIVAL OF THE COLD FRONT SHORTENS THE WINDOW BETWEEN CONVECTIVE
EVENTS ON BOTH SITES...LEAVING LITTLE TIME FOR AIR MASS RECOVERY.
LITTLE ENDED UP HAPPENING ACRS THE FCST AREA IN A SIMILAR
SCENARIO THIS PAST MONDAY. DID NOT MAKE MAJOR CHANGES TO POPS FM
PREV FCST...BUT WL LEAN TOWARD THE ECMWF SOLN AND FOREGO PLAYING
UP MON AFTN/EVE SVR RISK IN THE HWO.

TIMING OF PCPN CHCS BECOMES THE PRIMARY CHALLENGE IN LATER
PERIODS. THAT SHOWS ITSELF ALREADY TUE. ALTHOUGH A FEW OF THE
MODELS STILL GENERATED PCPN...THE TREND ON MOST WAS TO HAVE THE
FCST AREA DRY AND BTWN SYSTEMS. ALTHOUGH IT/S HARD TO ABSOLUTELY
RULE OUT PCPN...GIVEN RISING UPR HEIGHTS AND SFC RIDGE CROSSING
THE AREA...THE SUPPORT FOR SIG PCPN IS LOW...TO TRIMMED POPS.

NO SIG CHGS NEED TO BROAD-BASED EXTENDED FCST INITIALIZATION
GRIDS.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1236 PM CDT SAT AUG 30 2014

PLENTY OF IFR/MVFR CIGS ROTATING AROUND AN UPR TROF OVER THE WRN
GREAT LAKES REGION THIS AFTERNOON. RADAR CONTS TO SHOW NUMEROUS
BANDS OF SHWRS MOVING THRU NE WI WITH THE BACK EDGE SLOWLY WORKING
INTO WRN WI. EXPECT THIS PCPN TO GRADUALLY SHIFT EAST AND COME TO
AN END BY EARLY EVENING OVER ERN WI. WEAK SFC AND UPR RIDGING TO
OCCUR LATER TNGT WHICH MAY ALLOW SKIES TO AT LEAST BECOME PARTLY
CLOUDY FOR A TIME. PROBLEM IS FOG DEVELOPMENT AS MUCH OF THE
REGION HAS HAD HEAVY RAINFALL OVER THE PAST 24 TO 36 HOURS. ANY
IMPROVEMENT IN CIGS WL BE REPLACED BY REDUCED VSBYS INTO THE LIFR
TO IFR RANGE LATE TNGT AS THE FOG OVERSPREADS THE AREA. THIS FOG
IS EXPECTED TO GRADUALLY DISSIPATE BY LATE SUNDAY MORNING ALLOWING
FOR A RETURN TO VFR CONDITIONS FOR THE REST OF THE DAY.
&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....KALLAS
LONG TERM......SKOWRONSKI
AVIATION.......AK





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