Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 261050
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
550 AM CDT WED AUG 26 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 218 AM CDT WED AUG 26 2015

THE MAIN FORECAST CONCERN IS THE STUBBORN CLOUD DECK THAT IS IN
PLACE ACROSS THE WESTERN GREAT LAKES. THE CLOUD DECK IS IN
RESPONSE TO CYCLONIC FLOW AROUND A LARGE AREA OF LOW PRESSURE IN
PLACE ACROSS SOUTHERN JAMES BAY. THERE ARE SIGNS OF THE DECK
ERODING ACROSS WESTERN WISCONSIN AS DRIER AIR TRIES TO ADVECT IN
FROM THE WEST. THE MODELS SLOWLY ERODE THIS DECK FROM WEST TO EAST
TODAY AS RIDGING WORKS ITS WAY EAST AS THE AFOREMENTIONED LOW
TRANSITIONS FROM A CLOSED LOW TO A TROUGH AND TRACKS EAST OVER
WESTERN QUEBEC. THE 850 MB RH FIELDS SEEM TO MIMIC THIS QUITE
WELL...THEREFORE WILL SLOWLY WIPE OUT THE CLOUDS FROM WEST TO EAST
TODAY PER THE MODEL SOLUTIONS. WITH SOME SUNSHINE EXPECTED
TODAY...HIGHS ARE EXPECTED TO RISE INTO THE MIDDLE TO UPPER 60S
ACROSS THE SOUTH...WITH LOWER 70S ACROSS THE SOUTHERN CWA.

RIDGING AND MOSTLY CLEAR SKIES WILL LEAD TO OPTIMAL RADIATIONAL
COOLING CONDITIONS AS WINDS BECOME LIGHT UNDER A VERY LOOSE
PRESSURE GRADIENT. THIS SHOULD ALLOW LOW TEMPERATURES TO PLUMMET
INTO THE LOWER 40S ACROSS NORTH CENTRAL WISCONSIN...WITH A FEW
UPPER 30S NOT OUT OF THE QUESTION ACROSS THE EXTREME NORTH.
FURTHER SOUTH IT SHOULD BE A BIT WARMER...WITH LOWS SETTLING INTO
THE UPPER 40S TO LOWER 50S ACROSS CENTRAL AND EAST CENTRAL
WISCONSIN. THE LAST FEW DAYS OF RAINFALL ACROSS NORTH CENTRAL
WISCONSIN...COUPLED WITH LIGHT WINDS AND CLEAR SKIES WILL MOST
LIKELY LEAD TO PATCHY FOG ACROSS NORTH CENTRAL WISCONSIN
OVERNIGHT.

THE RIDGE WILL KEEP THE WEATHER QUIET INTO THURSDAY...AS SOUTHERLY
WINDS ON THE BACKSIDE OF THE HIGH BRING WARMER AIR INTO THE
WESTERN GREAT LAKES. ABUNDANT SUNSHINE AND WARM AIR ADVECTION
SHOULD ALLOW DAYTIME HIGHS TO SOAR INTO THE LOWER TO MIDDLE 70S
AWAY FROM LAKE MICHIGAN DURING THE AFTERNOON HOURS...PUSHING
TEMPERATURES BACK TO AROUND NORMAL FOR THIS TIME OF YEAR.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 218 AM CDT WED AUG 26 2015

THE LATEST ENSEMBLE MEANS POINT TOWARDS A PATTERN CHANGE OCCURRING
BY THIS WEEKEND...WHEN AN UPPER TROUGH SETTLES OVER THE WEST COAST
OF NORTH AMERICA...WHICH WILL LEAD TO SUB-TROPICAL RIDGING BUILDING
NORTH OVER THE EASTERN CONUS.  THIS PATTERN WILL LEAD TO ABOVE
NORMAL TEMPS RETURNING FOR THE 2ND HALF OF THE WEEKEND AND MUCH OF
NEXT WEEK.  THE ONLY SYSTEM TO REALLY CONTEND WITH IS A WEAK
SHORTWAVE MOVING OVER THE CENTRAL AND SOUTHERN GREAT LAKES EARLY
THIS WEEKEND.  THE GFS LOOKS TOO STRONG AND FARTHER NORTH WITH THE
SYSTEM.  SO WILL LEAN ON OTHER GUIDANCE...INCLUDING THE ECMWF AND
GEM.  THEREAFTER...MODEL AGREEMENT BREAKS DOWN BY SUNDAY.  WILL RELY
ON THE ECMWF AND GFS ENSEMBLE MEAN FOR LATER PERIODS.

THURSDAY NIGHT THROUGH FRIDAY NIGHT...SHORTWAVE ENERGY WILL MOVE
INTO WESTERN IOWA THURSDAY NIGHT.  THOUGH THIS SYSTEM WILL BE TOO
FAR AWAY FOR ANY DIRECT IMPACTS...WILL SEE WARM/MOIST ADVECTION
OCCURRING AHEAD OF THE SYSTEM OVER THE WESTERN GREAT LAKES.  MID-
LEVEL LAPSE RATES LOOK RATHER POOR IN THE WARM ADVECTION
REGIME...THOUGH MODEST INSTABILITY LOOKS TO PUSH INTO FAR N-C
WISCONSIN LATE.  THINK COULD SEE A FEW SHOWERS/ISOLD STORMS POP UP
OVER THE NORTH...BUT ALSO THINK PRECIP CHANCES LOOK OVERDONE.  WILL
BACK OFF A LITTLE.  BETTER CHANCES OF RAINFALL WILL ARRIVE ON FRIDAY
WHEN THE SOUTHERN MOVES INTO SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS.  WILL ALSO HAVE A WEAK FRONT MOVE INTO THE SOUTHERN LAKE
SUPERIOR REGION.  SO CHANCES FOR LOOK HIGHEST OVER THE FAR
NORTH...AND ALSO OVER CENTRAL WISCONSIN.  WILL RECONFIGURE POPS A
LITTLE.  THE SHORTWAVE CONTINUES TO MOVE TO THE EAST FRIDAY
NIGHT...WHICH WOULD PLACE HIGHER POPS OVER EASTERN WI.  NO
SIGNIFICANT CHANGES TO TEMPS.

REST OF THE FORECAST...MORNING CLOUDS SHOULD GIVE WAY TO MORE SUN ON
SATURDAY AS THE SHORTWAVE EXITS THE REGION.  THEN WILL SEE MID-LEVEL
RIDGING BUILD INTO THE WESTERN GREAT LAKES SUNDAY AND MONDAY...WHICH
WILL BE THE BEGINNING OF A WARMING TREND.  PERHAPS A CHANCE OF RAIN
SNEAKS INTO THE REGION BY NEXT WEDNESDAY. OTHERWISE...TEMPS WILL BE
RETURNING TO THE 80S BY MONDAY.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 550 AM CDT WED AUG 26 2015

SATELLITE IMAGERY SHOWS SIGNIFICANT BREAKS IN THE CLOUD DECK
ACROSS NORTH CENTRAL WISCONSIN EARLY THIS MORNING. DESPITE THIS
EROSION...SOME STRATOCUMULUS CLOUDS ARE EXPECTED TO REDEVELOP THIS
MORNING...HOWEVER MIXING AND WARMING TEMPERATURES ALOFT SHOULD
ALLOW CLOUDS TO DECREASE FROM WEST TO EAST LATER IN THE DAY. LIGHT
WINDS AND CLEAR SKIES SHOULD FACILITATE SOME FOG DEVELOPMENT AWAY
FROM THE LAKESHORE OVERNIGHT...WITH THE LOWEST VSBYS AT RHI WHERE
MOISTURE FROM SEVERAL DAYS OF RAINFALL SHOULD LEAD TO THICKER FOG.
&&

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

$$

SHORT TERM.....KURIMSKI
LONG TERM......MPC
AVIATION.......KURIMSKI



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