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000
FXUS63 KGRB 121137
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
637 AM CDT SUN MAY 12 2013

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 324 AM CDT SUN MAY 12 2013

LAKE ENHANCED SNOW WAS FALLING OVER FAR NORTHCENTRAL
WISCONSIN AT 3 O`CLOCK THIS MORNING. A DUSTING OF SNOW WAS COVERING
THE GRASS OVER MUCH OF VILAS COUNTY. THESE SNOW SHOWERS WILL
DIMINISH THIS MORNING AS DRIER AIR ARRIVES FROM THE NORTH AND
CONVECTIVE HEATING CAUSE DISRUPTION OF THE SNOW BANDS. OTHERWISE
MOTHERS DAY WILL BE BLUSTERY AND COOL WITH CLOUDS GIVING WAY TO
SUNSHINE.

LARGE SURFACE HIGH STRETCHING FROM LAKE WINNIPEG TO THE CENTRAL
PLAINS WILL DRIFT ACROSS WISCONSIN TONIGHT AND SET THE STAGE FOR A
FROST OR FREEZING TEMPERATURES OVER MUCH OF THE AREA EXCEPT RIGHT
ALONG THE LAKE AND BAY. FROST ADVISORIES AND FREEZE WARNINGS ARE
IN EFFECT FOR CENTRAL AND EAST CENTRAL WISCONSIN. THEY WOULD ALSO
BE IN EFFECT FOR NORTHERN WISCONSIN BUT THEY ARE NOT ISSUED THIS
EARLY IN THE SEASON. LOWS MAY DROP INTO THE UPPER TEENS IN THE
USUAL COLD PLACES WITH 20S TO LOW 30S ELSEWHERE. THIS COULD BREAK
RECORD LOWS FOR MONDAY IN MANY LOCATIONS. RECORD LOWS FOR MAY
13TH INCLUDE 25 AT APPLETON...27 AT EAGLE RIVER...30 AT GREEN BAY...
30 AT MANITOWOC... 28 AT MARINETTE...28 AT OSHKOSH...25 AT RHINELANDER
AND 26 AT WAUSAU.

MONDAY WILL HAVE SUNSHINE FADING BEHIND INCREASING MIDDLE AND HIGH
CLOUDS AS A WARM FRONT APPROACHES FROM THE SOUTHWEST. LIGHT RAIN
SHOWERS ARE POSSIBLE LATE IN THE DAY OVER THE WESTERN PORTION OF
THE FORECAST AREA BUT THE AIR IS DRY SO IT MIGHT JUST BE
SPRINKLES OR VIRGA.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 324 AM CDT SUN MAY 12 2013

A LOW AMPLITUDE NEAR ZONAL FLOW TO BE IN PLACE ACROSS THE CONUS
THRU MID-WEEK BEFORE STARTING TO AMPLIFY INTO UPR TROFS ON EACH
COAST AND AN UPR RDG BUILDING OVER THE CNTRL CONUS. BEST PCPN CHCS
APPEAR TO BE FOCUSED MON NGT INTO TUE WITH A QUICK RETURN OF
WARMER AIR AND THEN TUE NGT AS A CDFNT SLAMS INTO THE WARMER/MORE
MOIST AIR MASS. ANOTHER PCPN CHC MAY ARRIVE TOWARD NEXT WEEKEND AS
THE OLD FNT LIFTS BACK NWD. TEMPS LOOK TO BE ABOVE NORMAL FROM TUE
ONWARD.

THE SFC RDG SLIDES TO THE EAST MON NGT AND ALLOWS FOR A RETURN
FLOW TO DEVELOP ACROSS THE WRN GREAT LAKES. THE RESULTANT WAA
KICKS INTO OVERDRIVE DURING THE OVRNGT HOURS AS 8H TEMPS RISE INTO
THE LWR TEENS (C) BY DAYBREAK AND THIS COULD LEAD TO AT LEAST A
CHC OF RAIN SHWRS ACROSS THE FCST AREA. MIN TEMPS TO BE MUCH
WARMER COMPARED TO SUNDAY NGT WITH READINGS ONLY DROPPING INTO THE
LWR TO MID 40S.

AS A NRN STREAM SHORTWAVE TROF MOVES ACROSS THE NRN PLAINS TUE...
INCREASING SW WINDS WL HELP TO LIFT A WRMFNT NEWD INTO AT LEAST
WRN/SRN WI BY 00Z WED. CONTINUED WAA NORTH OF THIS FNT COULD
LINGER SHWR CHCS OVER NRN WI AND AT LEAST...KEEP MORE CLOUDS IN
PLACE WHICH WOULD PREVENT TEMPS FROM REALLY TAKING OFF. AREAS
SOUTH OF THE WRMFNT WL BECOME VERY WARM AND CAPPED WITH MORE
SUNSHINE ANTICIPATED. TEMPS OVER PARTS OF CNTRL WI COULD EASILY
REACH THE LWR 80S BY LATE TUE AS 8H TEMPS SOAR TO AROUND +20C.

THE SHORTWAVE TROF CONTS TO TRACK EAST INTO SRN ONTARIO TUE NGT
AND HELP TO DRIVE A MODEST CDFNT THRU WI. MDLS INDICATE STRONG
INSTABILITY TO BE IN PLACE OVER WI BEFOR THE CDFNT ARRIVES. WHILE
STEEP MID-LEVEL LAPSE RATES DO SEEM LEGIT...BELIEVE THE MDLS ARE
OVERDOING THE AMOUNT OF LOW-LEVEL MOISTURE TO BE PRESENT WHICH
IN TURN IS SENDING LI`S MUCH TOO LOW AND CAPE VALUES MUCH TOO
HIGH. IN ADDITION...THE ATMOSPHERE MAY BECOME TOO CAPPED TO ALLOW
TSTMS TO FULLY DEVELOP. HAVE KEPT THUNDER IN THE FCST AND WHILE A
FEW STORMS COULD BE STRONG (IF ABLE TO BREAK THE CAP)...A WIDESPREAD
SEVERE EPISODE LOOKS DOUBTFUL. THE CDFNT SETTLES TO OUR SOUTH
TOWARD CNTRL IL ON WED AND BEGINS TO STALL AS IT ENCOUNTERS AN UPR
RDG OVER THE SE CONUS. THERE MAY BE A LINGERING SHWR FIRST THING
WED MORNING OVER E-CNTRL AS THE FNT PULLS AWAY...HOWEVER THE REST
OF WED LOOKS TO BE DRY WITH WEAK HI PRES SITUATED TO OUR WEST.
EVEN WITH THE PASSAGE OF THE CDFNT...MAX TEMPS OVER NE WI ON WED
TO STILL BE ABOVE NORMAL THANKS MAINLY TO THE MILD START TO THE DAY.

UNDER THE ASSUMPTION THAT THIS FRESHLY STALLED BOUNDARY REMAINS
THAT WAY...DRAPED FROM SRN IOWA TO NRN INDIANA...ANY SHWR/TSTM
ACTIVITY WOULD REMAIN TO OUR SOUTH THRU THU. NOT QUITE SURE WHAT
TO MAKE OUT OF THE GFS ON THU AS IT HAS ANOTHER BOUNDARY OVER THE
UPR MS VALLEY. NONE OF THE OTHER LONG-TERM MDLS SHOW THIS BOUNDARY...
THUS HAVE TO QUESTION THE GFS FROM THU ONWARD. PREFER TO KEEP THE
PCPN TO OUR SOUTH AND KEEP THU DRY WITH MAX TEMPS MAINLY IN THE
MIDDLE 70S.

BY THE END OF WEEK...A PRONOUNCED UPR TROF IS PROGGED TO BE
SITUATED OVER THE ROCKIES WITH DOWNSTREAM UPR RIDGING LOCATED OVER
THE CNTRL CONUS. AN INCREASE IN SOUTH WINDS AHEAD OF THE UPR TROF
WL PULL GULF MOISTURE NWD AND DEPENDING ON WHERE THE OLD STALLED
BOUNDARY TO EXIST...ALLOW FOR A WIDE AREA OF PCPN TO DEVELOP. ONE
WOULD HAVE TO BELIEVE THAT THIS BOUNDARY WOULD EVENTUALLY LIFT
BACK NORTH AS A WRMFNT AND INCREASE THE PCPN CHCS OVER NE WI. HAVE
FAVORED CARRYING A HIGHER POP ON SAT VERSUS FRI FOR NOW USING A
CONSENSUS SOLN...BUT THIS COULD EASILY CHANGE IN THE COMING DAYS.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 637 AM CDT SUN MAY 12 2013

SCATTERED TO BROKEN CLOUDS BETWEEN 3000 FT AND 4000
FT THIS MORNING WILL GRADUALLY RISE DURING THE AFTERNOON BUT ALSO
DISSIPATE WITH CLEAR KIES AND LIGHT WINDS EXPECTED OVERNIGHT.
FROST MAY FORM ON AIRCRAFT LATE TONIGHT. MONDAY WILL START OUT
SUNNY WITH MIDDLE AND HIGH CLOUDS INCREASING IN THE AFTERNOON.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 1 AM TO 7 AM CDT MONDAY FOR WIZ022-038>040-
048>050-073-074.

FREEZE WARNING FROM 1 AM TO 7 AM CDT MONDAY FOR WIZ020-030-031-
035>037-045.
&&

$$

SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......RDM