Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 012349
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
649 PM CDT WED APR 1 2015

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 222 PM CDT WED APR 1 2015

MAIN FOCUS IN THE SHORT TERM IS THE PRECIP CHANCES OVERNIGHT INTO
THURSDAY AS A FRONT CROSSES THE CWA.


UPPER LEVEL FORCING WILL BE INCREASING AS A SURFACE FRONT MOVES
THROUGH NORTHEAST WISCONSIN. A SHARP 500MB SHORTWAVE WILL PUSH
THROUGH THE GREAT LAKES REGION JUST AS THE RRQ OF A 300MB
JETSTREAK MOVES OVERHEAD. THIS COMBINED WITH THE FRONT ITSELF
MEANS THERE WILL BE NO LACK OF FORCING WITH THIS SYSTEM. AMPLE
MOISTURE WILL ALSO BE AVAILABLE AS CONTINUED SOUTHERLY LOW LEVEL
FLOW AHEAD OF THE COLD FRONT WILL PUMP MOIST AIR NORTH INTO NE
WISCONSIN. PWATS THROUGH THE OVERNIGHT PERIOD WILL INCREASE TO
AROUND 1INCH...WHICH IS 2SD ABOVE NORMAL FOR THIS TIME OF YEAR.
THE MAIN INGREDIENT THAT KEEPS THIS FROM BEING A HARD HITTING RAIN
EVENT IS THE FACT THAT THE BEST SFC CONVERGENCE ON THE FRONT WILL
BE SOUTH OF OUR AREA. EITHER WAY...ANY RAIN WILL BE BENEFICIAL FOR
OUR AREA AS IT HAS BEEN ABNORMAL DRY SO FAR THIS YEAR.

MODELS CONTINUE TO SHOW A SLOWER TREND IN THE ARRIVAL OF THE COLD
FRONT AND PRECIPITATION. THEREFORE...HAVE FOLLOWED THE SLOWER
SOLUTIONS AND DELAYED PRECIPITATION MOVEMENT FROM WEST TO EAST.
WITH THE FRONT NOT EVEN ENTERING THE CWA UNTIL 06Z THURSDAY...KEPT
THINGS RY UNTIL THEN. THE FRONT WILL CROSS THE STATE THROUGH THE
NIGHT...WITH THE HEAVIEST RAINFALL IN CENTRAL WISCONSIN TOWARDS
THE FOX VALLEY WHERE MOISTURE AVAILABILITY WILL BE HIGHEST AND
CONVERGENCE ALONG THE FRONT WILL BE BETTER. KEPT THUNDER CHANCES
AS WELL ALONG THE FRONT. STRONG LIFT AND SOME ELEVATED INSTABILITY
WILL BE ENOUGH TO GET AT LEAST SOME RUMBLES OF THUNDER OVERNIGHT.

THURSDAY MORNING THE FRONT WILL BE IN EASTERN WISCONSIN. EXPECTED
RAIN TO BE ONGOING AT DAYBREAK AND FOR THE MORNING COMMUTE IN THE
FOX VALLEY AND ALONG THE LAKESHORE. AS THE FRONT CONTINUES TO
MARCH EASTWARD...SO WILL THE PRECIP. FRONT SHOULD CLEAR THE
STATE BY 18Z AT THE LATEST ON THURSDAY...WITH DRYING CONDITIONS
IN THE AFTERNOON. WINDS WILL TURN NORTHWEST AND BE GUSTY AS A DRY
SLOT PUNCHES INTO THE STATE AND MIXING INCREASES IN THE AFTERNOON.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 222 PM CDT WED APR 1 2015

MEAN FLOW DURING THIS PERIOD FEATURES GENERAL TROF ACROSS EASTERN
CANADA AND NE US WITH RIDGE ACROSS THE WEST...OCCASIONALLY
UNDERCUT BY PACIFIC ENERGY. SYSTEMS WILL AFFECT FORECAST AREA
FROM TIME TO TIME...BUT PRECISE TIMING WILL BE DIFFICULT.

OVERALL...TEMPS WILL PROBABLY AVERAGE BELOW NORM FOR THE PERIOD...BUT
ONE OR TWO DAYS ABOVE NORMALS POSSIBLE AS POSITION OF FRONTAL BOUNDARIES
WILL HAVE LARGE EFFECT ON MAX TEMPS IN PARTICULAR. COLD EASTERLY
FLOW WILL BE A MAJOR PLAYER.

SUBTLE DIFFERENCES BETWEEN GFS AND ECMWF WITH RESPECT TO TIMING
OF SYSTEMS BEYOND SATURDAY...SO PRECIP FORECAST IN PARTICULAR WILL
BE A BROAD CONSENSUS SOLUTION. BUT BOTH MODELS INDICATE A PERIOD
OF WET WEATHER MON-TUE NIGHT...WITH THE ECMWF MOST AGGRESSIVE WITH QPF.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 648 PM CDT WED APR 1 2015

A COOL FRONT WILL MOVE ACROSS THE REGION LATE TONIGHT
INTO EARLY THURSDAY MORNING.  SCATTERED SHOWERS WILL EXIT FAR
NORTH-CENTRAL WISCONSIN EARLY THIS EVENING WHICH WILL LEAVE VFR
CONDITIONS FOR MOST OF THE NIGHT UNTIL LATE.  THE LATEST MODELS
HAVE SLOWED DOWN THE FRONT SOME...SO HAVE BACKED OFF A MENTION OF
PRECIP UNTIL AFTER 08Z.  BUT THE MODELS ALSO VARY WITH THE AMOUNT
PRECIP INCOMING SO REMAINED CONSERVATIVE WITH THE CIGS AND VSBYS.
SHOWERS COULD CONTINUE UNTIL THE END OF THE TAF PERIOD OVER EASTERN
WISCONSIN.  OTHER THAN RAIN CHANCES/TIMING...A STRONG LOW LEVEL JET
WILL LEAD TO WIND SHEAR UNTIL THE FRONT DRAWS CLOSER.

&&

.FIRE WEATHER...
ISSUED AT 222 PM CDT WED APR 1 2015

ANOTHER PERIOD OF INCREASED FIRE DANGER IS POSSIBLE ON THURSDAY
AFTERNOON...AS A DRY SLOT BRINGS CLEARING SKIES AND GUSTY WEST
WINDS TO THE REGION...AND RELATIVE HUMIDITY DROPS INTO THE
20 TO 25 PERCENT RANGE IN THE SANDY SOIL REGIONS OF NC/C/NE WI.
THE BIG QUESTION WILL BE WHETHER OR NOT GRASSES AND OTHER FINE
FUELS CAN DRY OUT SUFFICIENTLY AFTER RECEIVING MODERATE RAINFALL
TONIGHT/EARLY THURSDAY.
&&

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

$$

SHORT TERM.....ALLEN
LONG TERM......JKL
AVIATION.......MPC
FIRE WEATHER...ALLEN






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