Special Marine Warning 13, NWS Green Bay, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
300 PM CDT FRI JUN 20 2008

.SHORT TERM...TONITE AND SATURDAY. FORECAST FOCUS ON PRECIP CHANCES.

SEVERE POTENTIAL WILL EXIST THRU EARLY THIS EVENING...THEN QUICKLY
END WITH THE LOSS OF DIURNAL HEATING. THE CHANCE FOR PRECIP WILL
CONTINUE TONITE AS A 500 MB VORT SWINGS THRU THE WESTERN GREAT
LAKES. WITH THE LOSS OF DAYTIME HEATING PRECIP WILL TRANSITION
OVER TO MORE SHOWERS AND LESS THUNDER.

THE REGION REMAINS IN NORTHWEST FLOW SATURDAY AS ANOTHER VORT
MOVES THRU THE WESTERN GREAT LAKES. THE SEVERE THREAT APPEARS TO
BE LOWER ON SATURDAY WITH LOWER CAPE VALUES THAN THIS AFTERNOON
AND VERY LITTLE WITH RESPECT TO DIRECTIONAL OR SPEED SHEAR.

.LONG TERM...MEAN FLOW TO TRANSITION TO MORE OF A ZONAL FLOW
ACROSS THE LWR 48 AS THE ERN CONUS UPR TROF SHIFTS INTO THE
ATLANTIC. THIS NEW FAST ZONAL FLOW WL CARRY SEVERAL PACIFIC
SYSTEMS ACROSS THE NRN TIER OF STATES...THUS TIMING OF THESE
SYSTEMS FOR PCPN CHCS IS THE MAIN FCST PBLM. TEMPS SHOULD AVERAGE
AT OR SLIGHTLY ABV NORMAL NXT WEEK.

EXPECT TO SEE A DIMINISHING TREND TO THE SHWRS AND TSTMS SAT
EVENING AS DAYTIME HEATING WANES AND THE ATM STABILIZES. HARD TO
DISCERN WHERE ANY SHRTWVS WL BE LOCATED FOR THE REMAINDER OF THE
NGT AS THESE FEATURE ROTATE AROUND THE GREAT LAKES NEARLY CLOSED
UPR LOW. FOR NOW...PREFER TO FOCUS ON SAT EVENINGS CHC POPS FOR
THE ENTIRE FCST AREA AND GO DRY FOR THE OVRNGT HRS.

WE SHOULD SEE ANOTHER ROUND OF SCT SHWRS/TSTMS ON SUNDAY AS
DAYTIME HEATING RETURNS...A SFC TROF DROPS SOUTH AND MORE SHRTWVS
ROTATE SWD INTO/THRU WI. COLDER TEMPS ALOFT WL BE OVR ERN WI WHICH
SHOULD LEAD TO A BETTER CHC OF PCPN SO HIGHER POPS THERE FROM THE
PREV SHIFT LOOKS JUSTIFIED. STEEP LAPSE RATES WL COMBINE WITH
CAPES APPROACHING 1500 J/KG AND LIS DOWN TO AROUND -4 TO PRODUCE
A FEW STG TSTMS BY SUNDAY AFTERNOON. SHEAR IS RATHER WEAK HOWEVER
AND BETTER INSTABILITY ACTUALLY TO OUR SOUTH. WL HAVE TO WATCH THE
STRONGER STORMS FOR THE POTENTIAL OF HAIL AND/OF GUSTY WNDS.

JUST LIKE SAT EVENING...ANTICIPATE A FEW SHWRS/TSTMS TO LINGER
INTO SUNDAY EVENING ACROSS E-CNTRL WI BEFORE SUNSET ENDS ANY
FURTHER HEATING. HI PRES WL BEGIN TO BUILD INTO THE WRN GREAT LKS
LTR SUNDAY NGT...THEREBY ALLOWING FOR DRIER CONDITIONS TO PREVAIL.
THIS HI PRES OVR THE WRN GREAT LKS WL COMBINE WITH A WEAK UPR RDG
TO PRODUCE A NICE...TYPICAL LATE JUNE DAY OVR NE WI. A GOOD AMT OF
SUNSHINE SHOULD ALLOW TEMPS TO BE CLOSE TO SEASONAL NORMS WITH
MOST LOCATIONS REACHING INTO THE MID TO UPR 70S.

AS BOTH THE SFC HI AND THE UPR RDG MOV EAST MON NGT...RETURN FLOW
WL BEGIN TO DRAW GULF MSTR NWD THRU THE MIDWEST. AS THE FIRST OF
THE RELATIVELY WEAK PACIFIC SYSTEMS APPROACHES ON TUE...THERE APRS
TO BE ENUF LIFT/INSTABILITY IN PLACE TO BRING A CHC POP TO NE WI.
BETTER CHC SHOULD REMAIN TO OUR WEST CLOSER TO A SHRTWV/WEAK CDFNT.
BULK OF SHRTWV ENERGY IS PROGGED TO DIVE SE TOWARD SRN WI/NE IA/NRN
IL TUE NGT...THEREFORE HAVE ATTEMPTED TO TIER POPS FROM SLGT CHC
NORTH TO MED CHC ACROSS MY SRN TIER OF COUNTIES. PRIMARY FOCUS TO
REMAIN TO OUR SOUTH ON WED. WHILE AN ISOLATED SHWR OR TSTM IS PSBL
OVR CNTRL/E-CNTRL WI...JUST DO NOT SEE ENUF INSTABILITY OR FORCING
OVR THE NORTH SO HAVE REMOVED PCPN WORDING FROM WEDS FCST THERE.

ANOTHER WEAK AREA OF HI PRES TO THEN SETTLE OVR THE RGN FOR WED
NGT AND THU SO HAVE OPTED TO RUN WITH A DRY FCST. THE NXT PACIFIC
SYSTEM MOVS INTO THE WRN GREAT LKS THU NGT INTO FRI AND WITH
SOUTHERLY WNDS BRINGING GULF MSTR BACK INTO WI...WL NEED TO
MENTION CHC POPS FOR THIS TIME PERIOD.
&&

.AVIATION...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL
MOVE ACROSS AIRPORT LOCATIONS SOUTHEAST OF A WAUSAU TO MARINETTE
LINE THIS EVENING. ONLY MVFR CEILINGS ARE EXPECTED FOR A BRIEF PERIOD OF
TIME AS THE STORMS PASS OVER THE AIRPORT. SOME OF THE STORMS COULD
PRODUCE WIND GUSTS FROM 40 TO 45 KNOTS WI LARGE HAIL. THE SEVERE
WEATHER AND THUNDERSTORM THREAT WILL DIMINISH BY MIDNIGHT WITH
MAINLY SHOWERS EXPECTED LATER TONIGHT.

VFR CONDITIONS EXPECTED SATURDAY WITH SCATTERED MVFR CONDITIONS AS
SHOWERS AND THUNDERSTORMS DEVELOP.
&&

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

KURIMSKI/KALLAS