Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 122013
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
313 PM CDT FRI SEP 12 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 312 PM CDT FRI SEP 12 2014

STRONG UPWARD VERTICAL MOTION PRODUCED BY THE LEFT EXIT REGION OF
A QUICK MOVING UPPER TROUGH WAS SUFFICIENT TO PRODUCE LIGHT RAIN
ACROSS THE AREA DESPITE STRONG SURFACE HIGH ACROSS THE AREA. THE
JET WILL EXIT EASTERN WISCONSIN THIS EVENING WITH RAIN ENDING FROM
WEST TO EAST.

SKIES SHOULD BEGIN TO CLEAR LATER TONIGHT PROVIDING THE OPPORTUNITY
FOR FROST TO FORM ACROSS CENTRAL AND NORTHCENTRAL WISCONSIN. TEMPERATURES
DO NOT HAVE FAR TO FALL FROM AFTERNOON READINGS IN THE MIDDLE TO UPPER
40S. IF SKIES CLEAR FASTER THEN A FREEZE WARNING MAY BE NEEDED. SUNNY
SKIES AND SLIGHTLY MILDER WEATHER EXPECTED SATURDAY WITH LIGHT WINDS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 312 PM CDT FRI SEP 12 2014

BROAD TROUGH OVER THE CENTRAL CONUS THIS WEEKEND WILL GRADUALLY
SHIFT TO THE EASTERN GREAT LAKES REGION TOWARD THE LATTER PART OF
NEXT WEEK. THE ONLY REASONABLE CHANCE TO SEE ANY MEASURABLE PRECIPITATION
WILL BE EARLY NEXT WEEK WHEN A COUPLE OF RELATIVELY BENIGN SHORTWAVE
IMPULSES TRAVERSE THE BASE OF THE TROUGH. THESE SYSTEMS WILL BE WEAK
AND WILL HAVE ACCESS TO LIMITED MOISTURE THUS EXPECT GENERALLY BELOW
NORMAL RAINFALL THE UPCOMING WORK WEEK. AS THE UPPER-LEVEL FLOW
BECOMES SOMEWHAT MORE ZONAL DURING THE LATTER HALF OF NEXT
WEEK...AVERAGE DAILY Y TEMPERATURES SHOULD SLOWLY CREEP BACK UP
CLOSER TO NORMAL FOR THE MIDDLE OF SEPTEMBER. OVERALL THE UPCOMING
WORK WEEK LOOKS TO BE RELATIVELY TRANQUIL AS IT WILL BE DOMINATED
BY SURFACE HIGH PRESSURE.

FIRST SHORTWAVE IMPULSE IS FORECAST TO AFFECT THE AREA SUNDAY
AFTERNOON WITH ASSOCIATED SURFACE COLD FRONT IMPINGING ON THE
NORTHCENTRAL WISCONSIN BY 00Z MONDAY. CONSENSUS OF THE MODEL
GUIDANCE SUGGESTS BEST CHANCE FOR SCATTERED SHOWER ACTIVITY TO
DEVELOP ALONG THE FRONT OVER NORTHERN WISCONSIN BY EARLY
AFTERNOON WHERE LARGE-SCALE FORCING IS SOMEWHAT STRONGER. THIS
SCATTERED ACTIVITY SHOULD QUICKLY SHIFT OFF TO THE EAST OVERNIGHT
AS THE COLD FRONT SAGS SOUTHEAST ACROSS THE FORECAST AREA.
GUIDANCE ALSO LATCHES ONTO ANOTHER AREA OF MORE ORGANIZED
PRECIPITATION ASSOCIATED WITH AN IMPULSE TRAVERSING THE CENTRAL
MISSISSIPPI VALLEY IN THE VICINITY OF THE AFOREMENTIONED COLD
FRONT. IT APPEARS THIS ACTIVITY SHOULD REMAIN SOUTH OF THE
FORECAST AREA DURING THE DAY ON MONDAY.

HIGH PRESSURE THEN RE-ESTABLISHES ITSELF OVER THE WESTERN GREAT
LAKES MONDAY NIGHT AND TUESDAY. THIS AREA OF HIGH PRESSURE
APPEARS TO BE MORE OF A PACIFIC ORIGIN THUS AIR MASS SHOULD BE
ASSOCIATED WITH MORE SEASONAL TEMPERATURES. IF SKIES CAN CLEAR
SUFFICIENTLY MONDAY NIGHT...COLD SEE SOME MORNING LOWS APPROACHING
THE MIDDLE 30S BUT DOES NOT APPEAR A WIDESPREAD FROST IS VERY
LIKELY.

ANOTHER COLD FRONT THEN DROPS SOUTHEAST OUT OF CANADA SOMETIME ON
WEDNESDAY. TIMING OF THIS FEATURE IS DIFFICULT AS MODELS DIVERGE
ON STRENGTH AND SPEED. OPTED TO FOLLOW A BLEND OF THE GFS AND
CANADIAN WHICH SUGGESTS A WEAKER AND MORE PROGRESSIVE FROPA
TUESDAY NIGHT. GIVEN VERY WEAK FORCING AND LIMITED
MOISTURE...APPEARS THIS FROPA WILL BE DRY AND WILL HELP TO RE-
ESTABLISH CANADIAN HIGH PRESSURE OVER THE AREA. BROAD HIGH
PRESSURE WILL THEN DOMINATE THE FORECAST AREA FOR THE REMAINDER OF
THE WORK WEEK.

MORE SUBSTANTIAL SHORTWAVE IS FORECAST TO MOVE INTO THE DAKOTAS
EARLY NEXT WEEKEND BRINGING A BETTER CHANCE FOR MEASURABLE
PRECIPITATION MOSTLY LIKELY IN THE SATURDAY NIGHT OR SUNDAY TIME
FRAME.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1246 PM CDT FRI SEP 12 2014

AN UPPER LEVEL DISTURBANCE WILL PRODUCE SOME LIGHT RAIN AND AREAS
OF MVFR CEILINGS THIS AFTERNOON AND EVENING. IT SHOULD END FROM
WEST TO EAST LATER TONIGHT WITH CLEARING SKIES. WHERE SKIES CLEAR
THERE IS A GOOD CHANCE OF FROST AND FOG. ANY FOG OR FROST THAT
DOES OCCUR SHOULD END BY 14Z SATURDAY WITH GOOD FLYING WEATHER
EXPECTED SATURDAY AND SUNDAY.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 3 AM TO 8 AM CDT SATURDAY FOR WIZ005-010>012-
018-019-030-035-036.
&&

$$

SHORT TERM.....RDM
LONG TERM......ESB
AVIATION.......RDM





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