Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 041944
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
244 PM CDT FRI SEP 4 2015

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SYNOPSIS...
ISSUED AT 244 PM CDT FRI SEP 4 2015

WARM AND HUMID THROUGH MOST OF THE LABOR DAY WEEKEND...WITH A
ROUND OF THUNDERSTORMS SUNDAY NIGHT INTO MONDAY MORNING.

AMPLITUDE OF THE LARGE SCALE PATTERN WL SOON PEAK...WITH A FAIRLY
DEEP TROF ALONG THE WEST COAST AND A RIDGE FM THE MID-MISSISSIPPI
VALLEY NEWD TO ONTARIO. NEXT WEEK THE PATTERN WL SETTLE BACK INTO
A LOWER AMPLITUDE REGIME WITH RIDGES NR THE COASTS AND A TROF
MID-CONTINENT.

WARM AND HUMID CONDITIONS WILL PERSIST EARLY AS LONG AS THE UPPER
RIDGE DOMINATES THE AREA...THEN TEMPERATURES SHOULD DROP BACK
CLOSER TO SEASONAL NORMALS NEXT WEEK. THE MAIN OPPORTUNITIES FOR
PRECIPITATION WILL BE WITH COLD FRONT CROSSING THE AREA SUNDAY
NIGHT INTO MONDAY...AND WITH A WAVE RIDGING EWD ALONG THE FRONT
NEXT WEEK. THE RESULT WL PROBABLY BE AOA NORMAL PCPN FOR MOST OF
THE AREA...WITH SIGNIFICANTLY HIGHER TOTALS IN ANY AREAS
REPEATEDLY AFFECTED BY STORMS.
&&

.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 244 PM CDT FRI SEP 4 2015

THE CHANCE FOR PRECIP SATURDAY BECOMES THE MAIN FOCUS FOR THE
SHORT TERM...WITH MORE FOG POSSIBLE TONIGHT.

CURRENT MESOANALYSIS AND WATER VAPOR IMAGERY SHOWED A FAIRLY
PROGRESSIVE BUT WEAKENING SHORTWAVE OVER THE DAKOTAS AND
MINNESOTA RIDING ALONG THE EDGE OF THE MAIN UPPER LEVEL
RIDGE...WITH SHOWERS AND THUNDERSTORMS DEVELOPING IN RESPONSE TO
THIS PIECE OF ENERGY. FURTHER EAST OF WISCONSIN...RIDGING
CONTINUED TO DOMINATED THE WEATHER PATTERN. THIS RIDGE SHOULD HOLD
THROUGH THE NIGHT...WITH FOG DEVELOPMENT AGAIN POSSIBLE. MIXING
LAYER WINDS WERE ON THE STRONGER SIDE SO DONT THINK VISIBILITIES
WILL CRASH...BUT LOW STRATUS SHOULD STILL PLAGUE MUCH OF NE
WISCONSIN...WITH THE WORST CONDITIONS IN NORTH CENTRAL WISCONSIN.
ANY FOG SHOULD LIFT THROUGH SATURDAY MORNING...MUCH LIKE WE HAVE
SEEN THE PAST FEW DAYS.

THE QUESTION THEN BECOMES WHICH FEATURE WILL WIN ON SATURDAY...THE
MAIN RIDGE OR THE NOTED SYSTEM AS IS MOVES UP AND OVER THE RIDGE
AXIS. FORECAST MODELS ARE ALL OVER THE PLACE AND SHOW LITTLE
AGREEMENT...SO COULD NOT ADD MUCH DETAIL WITH CONFIDENCE ON PRECIP
TIMING OR COVERAGE SATURDAY. TRIED TO TIME POPS WITH THE BEST
FORCING AND THE ARRIVAL OF BETTER WAA...HOWEVER LIFT SHOULD BE
BROAD AND WEAK. ENDED UP WITH SLIGHT CHANCE POPS FOR MUCH OF OUR
AREA. WHILE COULDNT ADD BETTER TIMING OR PLACEMENT FOR
SATURDAY...CONFIDENCE IS HIGH THAT WHATEVER DOES DEVELOP SHOULD BE
ISOLATED AND LOW IMPACT...AND SHOULDNT RUIN THE ENTIRE DAY.

SATURDAY WILL BE WARMER THAN TODAY...AND WITH INCREASING DEWPOINTS
IT WILL CERTAINLY FEEL LIKE SUMMER.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 244 PM CDT FRI SEP 4 2015

MAIN FCST ISSUE IS TIMING OF PCPN WITH THE FRONTAL SYSTEM
CROSSING THE AREA DURING THE LATTER HALF OF THE HOLIDAY WEEKEND.
THERE IS STILL SOME UNCERTAINTY CONCERNING WHETHER OR NOT
CONVECTION WITH SHRTWVS RIDING ARND THE UPR RIDGE WL AFFECT THE
AREA DURING THE EARLY PART OF THE WEEKEND. STAYED CLOSE TO PREV
FCST IN THIS REGARD...WITH LOW-CHC POPS ACRS THE N.

TIMING OF THE MAIN PCPN BAND WITH THE FRONT IS A LITTLE SLOWER
THAN YDA...AND WOULD NOT BE SURPRISED IF A LITTLE ADDITIONAL
SLOWING OCCURS. STRUCTURED FCST WITH LIKELY POPS ACRS THE W FOR
LATE SUN NGT...BUT TAPERED BACK TO CHC IN THE FAR E. STUCK WITH
ONLY HIGH CHC POPS IN THE E MONDAY MORNING...AS TIMING OF FROPA
MAY ONLY SUPPORT SCT COVERAGE AS THE FRONT CROSSES THAT AREA.

USED BLEND OF TOP PERFORMING GUIDANCE PRODUCTS FOR TEMPS...WITH
SOME ADJUSTMENT TO ACCOUNT FOR COOLER TEMPERATURE LAKESIDE. GLERL
LAKE SURFACE WATER TEMPERATURE ANALYSES INDICATED THAT THE VERY
COLD WATER THAT UPWELLED ALONG THE WRN SHORE HAS WARMED...THOUGH
IT IS STILL COOL ENOUGH TO NECESSITATE HAVING COOLER MAX TEMPS
NEAR THE LAKE.

MED RANGE MODELS PRETTY MUCH AGREE THAT FRONT WL SLOW AS IT PUSHES
S OF THE FCST ARA AND A SIG WV WL RIDE EWD ALONG THE BOUNDARY
EARLY NEXT WEEK. NOT UNEXPECTEDLY AT THAT TIME RANGE...DETAILS OF
PLACEMENT/TIMING OF THE GREATEST PCPN DIFFERED AMONG THE MODELS.
THE CHC POPS SUPPLIED BY THE EXTENDED FORECAST INITIALIZATION
GRIDS SEEMED ADEQUATE FOR NOW...WITH NO SIG CHGS NECESSARY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1107 AM CDT FRI SEP 4 2015

ONCE ANY LINGERING BKN MVFR CLOUDS SCATTERED OUT IN CENTRAL AND
EAST CENTRAL WISCONSIN...VFR CONDITIONS ARE EXPECTED THIS
AFTERNOON INTO EARLY TONIGHT WITH LIGHT WINDS. OVERNIGHT...MUCH
LIKE THE PAST FEW DAYS...FOG SHOULD DEVELOP AS SKIES BECOME
MOSTLY CLEAR AND WINDS GO LIGHT. STRONGER MIXING AT THE BOUNDARY
LEVEL SHOULD KEEP VISIBILITIES IN THE IFR RANGE...HOWEVER IFR TO
LIFR CLOUDS MAY DEVELOP. HEADING INTO SATURDAY MORNING...THE FOG
AND LOW CIGS SHOULD IMPROVE BY LATE MORNING...WITH VFR CONDITIONS
AND CONTINUED LIGHT WINDS AFTER THAT.
&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....ALLEN
LONG TERM......SKOWRONSKI
AVIATION.......ALLEN



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