Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 061732
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1232 PM CDT FRI MAY 6 2016

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 408 AM CDT FRI MAY 6 2016

WARM AIR ADVECTION AHEAD OF AN APPROACHING COLD FRONT WILL RULE
OVER THE WESTERN GREAT LAKES TODAY. THIS WARM AIR ADVECTION WILL
CAUSE DAYTIME HIGHS AWAY FROM LAKE MICHIGAN TO SOAR INTO THE UPPER
70S TO LOWER 80S. IN ADDITION A TIGHTENING PRESSURE GRADIENT WILL
LEAD TO SOME GUSTY WINDS BY THE AFTERNOON AS DEEP MIXING BRINGS
DRIER AIR TO THE SURFACE THAN IS CURRENTLY FORECAST BY THE MODELS.
THEREFORE WILL CONTINUE TO KEEP DEW POINTS BELOW MOS GUIDANCE
VALUES...WITH RELATIVE HUMIDITIES DROPPING INTO THE 20 TO 30
PERCENT RANGE THIS AFTERNOON. THE WARM...DRY WEATHER COMBINED WITH
SOME HIGHER GUSTS THIS AFTERNOON WILL CAUSE ELEVATED FIRE DANGER
CONCERNS ACROSS THE AREA TODAY. ALTHOUGH INSTABILITY WILL INCREASE
TODAY GIVEN THE ABUNDANT WARMING...INSTABILITY WILL BE ELEVATED
WITH RAIN NOT EXPECTED TO DEVELOP UNTIL THE COLD FRONT ARRIVES
TONIGHT AND PROVIDES A LIFTING MECHANISM FOR THE ELEVATED
INSTABILITY.

THE COLD FRONT WILL SWEEP THROUGH TONIGHT...BRINGING SHOWERS AND
THUNDERSTORMS TO THE WESTERN GREAT LAKES THROUGH SATURDAY MORNING.
INSTABILITY WITH THIS FRONT WILL BE RELATIVELY MEAGER...WITH
MUCAPES OF 500 TO 1000 J/KG. GIVEN THE ELEVATED NATURE OF THE CAPE
AND THE FRONT MOVING THROUGH WELL AFTER PEAK HEATING THE
THUNDERSTORMS ARE NOT EXPECTED TO BE STRONG WITH LITTLE TO
ANYTHING IN THE WAY OF HAIL OR WIND.

CLEARING SKIES AND COOLER TEMPERATURES ARE EXPECTED BEHIND THE
FRONT ON SATURDAY...HOWEVER HIGH TEMPERATURES ARE STILL EXPECTED
TO GET INTO THE 60S AS THE PUSH OF COLD AIR BEHIND THESE FRONTS
GETS LESS PROLIFIC AS SUMMER APPROACHES.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 408 AM CDT FRI MAY 6 2016

THE LATEST ENSEMBLE MEANS CONTINUE TO INDICATE THAT SPLIT FLOW WILL
BE THE DOMINANT PATTERN ACROSS NORTH AMERICA FOR MUCH OF THE
UPCOMING WEEK.  FORECAST CONCERNS REVOLVE AROUND PRECIP POTENTIAL
NEXT WEEK WHEN AN UPPER LOW DRIFTS TOWARDS THE REGION.  THE MEDIUM
RANGE MODELS ARE IN RELATIVELY GOOD AGREEMENT THROUGH 00Z WED AND
WILL USE A BLEND OF THE GFS/ECMWF THRU THIS TIME.  THEREAFTER...WILL
LEAN ON THE ENSEMBLE MEANS.

SATURDAY NIGHT THRU SUNDAY NIGHT...MAINLY A QUIET PERIOD THANKS TO
NORTHWEST FLOW ALOFT AND A WEAK RIDGE OF HIGH PRESSURE AT THE
SURFACE.  A WEAK FRONT WILL TRY TO SAG INTO NORTHERN AND NORTHEAST
WISCONSIN ON SUNDAY BUT THE ATMOSPHERE LOOKS TOO DRY FOR ANY PRECIP.
WILL LIKELY SEE CLOUDS INCREASE LATE ON SUNDAY NIGHT AS LOW PRESSURE
MOVES ACROSS THE CENTRAL PLAINS.  LIGHT RAIN WILL PUSH INTO SOUTHERN
WISCONSIN LATE SUNDAY NIGHT BUT LIKELY FALL SHORT OF MOVING INTO
CENTRAL WI DUE TO AMPLE DRY AIR IN PLACE.  LITTLE CHANGE TO TEMPS
DURING THE PERIOD.

REST OF THE FORECAST...PERIODS OF RAIN WITH AN OCCASIONAL
THUNDERSTORM LOOK TO MOVE INTO THE REGION MONDAY THRU TUESDAY OF
NEXT WEEK.  UNLIKE THE PREVIOUS UPPER LEVEL SYSTEMS...THE DRY
AIRMASS WHICH WILL INITIALLY BE IN PLACE LOOKS TO GET OVERWHELMED BY
A SOUTHERLY FEED OF MOIST AIR. THERE MAY BE A RELATIVE LULL IN THE
PRECIP MIDWEEK AS THE FIRST UPPER LOW WEAKENS AND DEPARTS THE
REGION.  THEN A SECOND UPPER LOW WILL BRING MORE PRECIP BY THU AND
FRI OF NEXT WEEK.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1231 PM CDT FRI MAY 6 2016

VFR CONDITIONS TO PREVAIL THROUGH THE TAF PERIOD...HOWEVER A
TEMPORARY LOWERING OF CIGS/VSBYS ARE POSSIBLE WITH ANY
THUNDERSTORMS THAT WILL BE ASSOCIATED WITH THE PASSAGE OF A COLD
FRONT TONIGHT. THIS FRONT IS EXPECTED TO MOVE THROUGH THE RHI TAF
SITE BY MID-EVENING...THE AUW/CWA TAF SITES AROUND MIDNIGHT AND
THE GRB AND MTW TAF SITES BETWEEN 07Z AND 09Z. WINDS WILL VEER TO
THE NORTH BEHIND THE FRONTAL PASSAGE AND COULD BRIEFLY GUST OVER
20 KNOTS. HAVE ALSO INCLUDED LLWS TO THE TAF`S THIS EVENING AS
RELATIVELY LIGHT SW WINDS AT THE SURFACE WILL BE MET WITH A GUSTY
WEST WIND OVER 30 KNOTS ABOVE 1K FEET. VFR CONDITIONS SHOULD
CONTINUE INTO SATURDAY AFTERNOON...ALTHOUGH SOME HI-BASED CU OR
LOW-END ALTOCU IS EXPECTED TO DEVELOP.
&&

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

$$

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


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