Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 031026
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
526 AM CDT SUN MAY 3 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 338 AM CDT SUN MAY 3 2015

THUNDERSTORM TIMING TODAY INTO TONIGHT AS WELL AS POTENTIAL OF
SEVERE STORMS THE PRIMARY ISSUE FOR THIS PERIOD.

RADARS THIS MORNING SHOW SCATTERED SHOWERS AND STORMS OVER
MINNESOTA AHEAD OF THE COLD FRONT AND ANOTHER CLUSTER OF SHOWERS
AND STORMS OVER IOWA ASSOCIATED WITH A WEAK SHORT WAVE DRIFTING IN
THE WEST TO SOUTHWEST FLOW. THIS IOWA SHORT WAVE TROUGH IS
PROGGED TO STAY SOUTH BUT DID NOTICE SOME MID LEVEL CLOUDS
GRADUALLY DRIFTING NORTHEASTWARD INTO SOUTHWEST WISCONSIN. PROGS
OVERALL KEEP THIS CONVECTION SOUTH BUT A FEW DO EXTEND SOME LIGHT
AMOUNTS INTO PARTS OF CENTRAL AND EAST CENTRAL WISCONSIN LATER
THIS MORNING.

OTHERWISE THE BRUNT OF THE CONVECTION TODAY WILL BE WITH THE
CONVERGENCE GENERATED ALONG THE COLD FRONT. UPPER JET SUPPORT
WELL NORTH OF THE AREA. WILL HAVE AN EARLIER START TIME OF THE
CONVECTION AROUND MID DAY FOR NORTH CENTRAL DUE TO POSSIBLE EARLY
MORNING MINNESOTA CONVECTION MAY HOLD TOGETHER AND REACH THIS
AREA.

STRONGEST STORMS WILL LIKELY ARRIVE MID TO LATE AFTERNOON OVER
NORTH CENTRAL WISCONSIN AND CENTRAL WISCONSIN DURING PEAK HEATING
PERIOD. SPC CONTINUES TO PLACE MUCH OF CENTRAL AND NORTH CENTRAL
IN A SLIGHT RISK. SOME MODEL ISSUES WITH RESPECT TO AVAILABLE
INSTABILITY DUE TO SURFACE DEWPOINTS TRENDS...NAM PRODUCES UP TO
2000 J/KG CAPES LATE THIS AFTERNOON OVER CENTRAL AND NORTH CENTRAL
WISCONSIN WHILE THE GFS FORECAST SOUNDINGS ARE BETWEEN 100O TO
1500. SOME LOWER TO MID 50S NOTED OVER THE CENTRAL PLAINS AND
ANTICIPATE SIMILAR VALUES LATER TODAY ALONG AND JUST AHEAD OF THE
COLD FRONT. CAPES OF 1000 TO 1500 J/KG WILL BE WORKING WITH AN
INCREASINGLY SHEARED ENVIRONMENT DUE TO THE MID LEVEL WESTERLY
FLOW. BY THE TIME THE STORMS REACH EAST CENTRAL WISCONSIN LATER
THIS EVENING...INSTABILITY DUE TO DAYTIME HEATING WILL
DIMINISH...BUT THE WESTERLY MID LEVEL WINDS WILL WORK INTO THE
AREA AS THE COLD FRONT PASSES. THE LINGERING SHEARED ENVIRONMENT
MAY BE ENOUGH TO MAINTAIN A FEW NEAR SEVERE STORMS THIS EVENING
OVER EAST CENTRAL WISCONSIN.

SHOWERS AND STORMS WILL BE ON THE DECREASE AFTER MIDNIGHT AND
TOWARD MONDAY MORNING AFTER FROPA. HIGH PRESSURE WILL BUILD INTO
NORTHWEST WISCONSIN MONDAY FOR SUNNY SKIES ACROSS THE NORTH. SINCE
THE COLD FRONT STALLS OVER NORTHERN OR CENTRAL ILLINOIS...CLOUDS
MAY HANG AROUND OVER EAST CENTRAL WISCONSIN. NORTHEAST WINDS OFF
THE LAKE MAY ALSO CONTRIBUTE TO LOWER LEVEL CLOUDS MONDAY. DUE TO
CLOUDS SUNDAY NIGHT...AND A WARM START MONDAY MORNING AND
DECREASING CLOUDS MONDAY...FORECAST MAX TEMPERATURES MAY REBOUND
INTO AT LEAST THE LOWER 70S AWAY FROM LAKE MICHIGAN AND THE BAY.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 338 AM CDT SUN MAY 3 2015

AMPLIFIED MEAN FLOW TO PERSIST THRU MUCH OF THE WEEK WITH A BROAD
UPR TROF OVER THE WRN CONUS AND AN UPR RDG OVER THE SE CONUS. THIS
PATTERN WOULD BRING A PREVAILING SW FLOW TO THE CNTRL CONUS
(INCLUDING WI) WHICH WL KEEP TEMPS ABOVE NORMAL AND ALLOW GULF
MOISTURE TO EASILY FLOW NWD. AN ACTIVE WEATHER PERIOD IS EXPECTED
FOR NE WI AS A WRMFNT MOVES THRU THE AREA LATE TUE INTO WED...
FOLLOWED BY A WEAKENING SHORTWAVE TROF/SFC CDFNT LATE IN THE WEEK.
THE EXPECTED PCPN SHOULD HELP TO ALLEVIATE THE DRY CONDITIONS/FIRE
DANGER OVER THE REGION.

THE SFC HI WL SLOWLY SHIFT TOWARD NE SECTIONS OF THE GREAT LAKES
TUE NGT...BUT KEEP A DRY E-NE WIND OVER THE FCST AREA. MEANWHILE...
WL BE WATCHING THE STALLED BOUNDARY TO OUR SOUTH WHICH MAY EDGE A
BIT NORTH IN RESPONSE TO AN INCREASING LOW-LEVEL JET OVER THE
PLAINS. NRN WI TO REMAIN MOSTLY CLEAR THRU THE NGT...HOWEVER EXPECT
CNTRL/E-CNTRL WI TO BECOME PARTLY TO MOSTLY CLOUDY OVRNGT AND
CANNOT RULE OUT A FEW LIGHT SHWRS REACHING OUR SRN TIER OF COUNTIES
TOWARD DAYBREAK AS ADDITIONAL SHWRS/TSTMS MOVE ALONG THE FRONTAL
BOUNDARY. MIN TEMPS TO RANGE FROM THE LWR TO MID 30S NEAR THE MI
BORDER...TO THE LWR TO MID 40 SOUTH.

MODELS SEEM CONVINCED NOW THAT THE STALLED BOUNDARY WL BEGIN TO
STEADILY LIFT NORTH AS A WRMFNT ON TUE IN RESPONSE TO A SIGNIFICANT
SHORTWAVE TROF MOVING NEWD THRU THE SRN ROCKIES. THE FNT IS EXPECTED
TO STRETCH ROUGHLY FROM SRN MN E-SE THRU THE WI/IL BORDER BY 00Z WED
WITH CONVERGENCE ALONG THE FNT/GULF MOISTURE LIFTING OVER THE FNT
LEADING TO MORE SHWR/TSTM ACTIVITY. MAY NEED TO BRING POPS NORTH A
TIER OF COUNTIES...LEAVING ONLY FAR NRN WI DRY THRU THE DAYLIGHT
HOURS. MORE CLOUDS/HIGHER POPS WL LEAD TO A COOLER DAY WITH MAX
TEMPS RANGING FROM THE LWR 60S SOUTH (COOLER LAKESIDE)...TO NEAR 70
DEGS ALONG THE MI BORDER.

CHC OF SHWRS/TSTMS WL CONT ACROSS NE WI TUE NGT AS THE WRMFNT SLOWLY
LIFTS NORTH INTO SRN WI. AS THE SHORTWAVE TROF MOVES TOWARD THE
CNTRL PLAINS ON WED...THE WRMFNT WL CONT TO LIFT NWD THRU WI AND
ESSENTIALLY BE NORTH OF THE FCST AREA BY LATE WED. ANTICIPATE AT
LEAST A CHC OF SHWRS/TSTMS TO ACCOMPANY THE WRMFNT...BUT BELIEVE
THE PCPN WL HAVE A TENDENCY OF BECOMING MORE ISOLATED IN NATURE
ACROSS CNTRL/E-CNTRL WI WED AFTERNOON AS THE MAIN FOCUS SHIFTS
NORTH WITH THE FNT AND THERE IS A LACK OF ANY TRIGGER IN THE SOUTH.
WED WL FEEL MORE LIKE A SUMMER DAY WITH MAX TEMPS RANGING FROM
AROUND 70 DEGS NORTH...UPR 70S CNTRL WI (COOLER NEAR LAKE MI) AND
DEW POINTS CLIMBING INTO THE 50S.

THE SHORTWAVE TROF IS PROGGED TO MOVE THRU THE CNTRL PLAINS WED
NGT AND BEGIN TO WEAKEN IN THE PROCESS. BY THU...WHAT IS LEFT OF
THE TROF WL REACH THE UPR MS VALLEY WITH A CDFNT EXTENDED SW THRU
THE CNTRL PLAINS. PCPN CHCS APPEAR MINIMAL WED NGT INTO THU
MORNING...HOWEVER AS BETTER MID-LEVEL FORCING/INCREASING
INSTABILITY BECOME MORE PREVALENT THU AFTERNOON...PCPN CHCS LOOK
TO BE ON THE INCREASE ONCE AGAIN. GUSTY SOUTH WINDS ON THU WL CONT
TO PUMP GULF MOISTURE INTO WI WITH DEW POINTS EXPECTED TO BE IN
THE MID TO UPR 50S. COMBINE THESE DEW POINTS WITH MAX TEMPS IN THE
75-80 DEG RANGE (AWAY FROM LAKE MI) AND WE WL HAVE A SUMMER FEEL
TO THE AIR MASS.

PCPN CHCS WL CONT THU NGT AS STRONGER WAA SURGES THRU WI AHEAD OF
THE ADVANCING CDFNT. THIS CDFNT IS FCST TO PUSH INTO WI ON FRI AND
SET THE STAGE FOR ADDITIONAL SHWRS/TSTMS. TOO EARLY TO DETERMINE
THE STRENGTH OF THESE STORMS...BUT WITH THE MODELS SHOWING LITTLE
IN THE WAY OF MID OR UPR SUPPORT...THIS WOULD LIMIT THE SEVERE
RISK. MAX TEMPS ON FRI SHOULD BE A FEW DEGS COOLER THAN THU DUE TO
THICKER CLOUDS/HIGHER CHC OF PCPN.

JUST LIKE ITS PREDECESSOR...THIS CDFNT IS FCST TO SAG SOUTH AND
EVENTUALLY STALL SOMEWHERE IN THE VICINITY OF THE WI/IL BORDER
NEXT WEEKEND. THE EXACT LOCATION OF THIS BOUNDARY WL ULTIMATELY
DETERMINE THE NRN EXTENT OF ANY PCPN IN THE VICINITY OF
CNTRL/E-CNTRL WI. FOR THE MOST PART...NRN WI REMAIN DRY NEXT SAT
AS HI PRES OVER SRN CANADA FEEDS DRIER AIR INTO NRN SECTIONS OF
THE GREAT LAKES. SAT WL ALSO BE COOLER BEHIND THE INITIAL CDFNT
WITH MAX TEMPS RANGING ONLY IN THE MID 50S LAKESIDE...TO THE LWR
70S OVER CNTRL WI.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 526 AM CDT SUN MAY 3 2015

VFR CONDITIONS WILL CONTINUE THIS MORNING AND INTO THE AFTERNOON
OVER EASTERN WISCONSIN. SHOWERS AND STORMS WILL BE ON THE INCREASE
THIS AFTERNOON OVER CENTRAL AND NORTH CENTRAL WISCONSIN AND AND
THEN INTO TONIGHT OVER EASTERN WISCONSIN. THE STORMS WILL DEVELOP
ALONG AND NEAR A COLD FRONT TRACKING OVER THE STATE. SCATTERED
MVFR/IFR CIGS/VSBYS AS WELL AS GUSTY WINDS AND HAIL CAN BE
EXPECTED WITH A FEW OF THE STRONG STORMS. ISOLATED SEVERE STORMS
WITH DAMAGING WINDS AND LARGE HAIL WILL ALSO BE POSSIBLE.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......KALLAS
AVIATION.......TDH






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