000
FXUS63 KGRB 180005
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
705 PM CDT FRI MAY 17 2013

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 222 PM CDT FRI MAY 17 2013

UPR FLOW ACRS NOAM WL GRADUALLY AMPLIFY THE NEXT FEW DAYS AS UPR
TROF FORMS OVER THE ROCKIES AND WRN PLAINS. THAT ENERGY...IN THE
FORM OF A CLOSED UPR LOW...WL SHIFT EWD INTO THE GREAT LAKES RGN
NEXT WK...AS ADDITIONAL ENERGY DROPS DOWN THE WEST COAST AND
REPLACES IT. SO BY LATE NEXT WEEK...UPR PATTERN WL EVOLVE TOWARD A
HIGHLY AMPLIFED SOMEWHAT BLOCKY PATTERN...WITH A SHARP RIDGE OVER
THE MIDDLE OF THE COUNTRY AND TROFS OVER THE PAC NW AND THE NERN
CONUS.

THE UPR PATTERN DOESN/T REALLY FAVOR A SIG DEPARTURE FROM NORMAL
TEMPS. THOUGH LIKE TDA...WE/LL PROBABLY HAVE SIG DAY TO DAY
VARIATIONS DUE TO CLDS/PCPN. UPR SYSTEM CROSSING THE AREA WL
LIKELY RESULT IN ABV NORMAL PCPN FOR THE PERIOD. THOUGH SOME PCPN
WL OCCUR THIS WEEKEND...THE BULK OF THE RAIN WL FALL DURING THE
EARLY TO MIDDLE PART OF NEXT WK.
&&

.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 222 PM CDT FRI MAY 17 2013

MID LEVEL FRONTOGENETIC FORCING IS EXPECTED TO WEAKEN LATE THIS
AFTERNOON. MEANWHILE...SURFACE WARM FRONT WEST AND SOUTH OF THE
STATE WILL TRIGGER ADDITIONAL SHOWERS AND STORMS WEST OF THE STATE.
UNCERTAINTY EXISTS WHEN AND WHERE SHOWERS AND STORMS WOULD OCCUR
DUE TO THE DIFFERENCES IN THE MODEL QPF OUTPUTS AND SOME OF THE
MESOSCALE MODELS INDICATING NO PRECIPITATION EARLY THIS EVENING.
DECIDED TO CARRY THE REST OF THE AFTERNOON PERIOD IN THE ZONE
FORECAST PRODUCT TO HIGHLIGHT ONGOING PRECIPITATION. FOR TONIGHT...
WENT WITH A CHANCE ACROSS THE ENTIRE AREA.

ON SATURDAY...THERE MAY BE SOME LINGERING SHOWERS ACROSS THE NORTH.
OTHERWISE SKIES WILL BECOME PARTLY SUNNY DURING THE AFTERNOON.
CONVECTIVE PARAMETERS WOULD INDICATED THERE WOULD BE A CHANCE OF
THUNDERSTORMS NORTHWEST AND WEST OF THE FOX VALLEY SATURDAY
AFTERNOON. ANY STORM WOULD PRODUCE LOCALLY HEAVY RAIN AND GUSTY
WINDS. WENT A LITTLE WARMER THAN GUIDANCE ACROSS PORTIONS OF CENTRAL
WISCONSIN...WHILE STAYING CLOSE TO GUIDANCE ACROSS THE NORTH AND
EAST DUE TO CLOUD COVER AND WINDS OFF THE BAY/LAKE.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 222 PM CDT FRI MAY 17 2013

GETTING A GOOD HANDLE ON PCPN CHCS LATER IN THE WEEKEND STILL
TOUGH AS MOIST SELY FLOW WL EXIST ACRS THE RGN AND REMNANTS OF SFC
BOUNDARY WL BE LIFTG NWD ACRS THE RGN. IN ADDITION...MIDDLE-LEVEL
LAPSE RATES PROGGED TO STEEPEN...INDICATING AT LEAST ELEVATED
INSTABILITY. ON THE OTHER HAND...UPR HEIGHTS WL BE RISING AND THE
UPR FLOW WL BECOME INCREASINGLY ANTICYCLONIC. KEPT SAT NGT DRY AND
CONFINED PCPN CHCS TO THE WRN 1/2 OF THE AREA SUN. THAT AREA WL BE
CLOSER TO MAIN UPR SYSTEM OUT W...AND MORE LIKELY TO GET CLIPPED
BY SHRTWVS EJECTING NEWD FM IT AND RIDING ARND BUILDING UPR RIDGE
OVER THE E. BUT AS MENTIONED EARLIER...THIS ISN/T A HIGH
CONFIDENCE FCST AND A CASE COULD POBABLY BE MADE FOR INCLUDING LOW
CHC POPS ACRS THE E.

UPR SYSTEM FM THE W WL EDGE CLOSER SUN NGT/MON/MON NGT...SO WENT
WITH INCREASED POPS FM W-E THESE PERIODS. THUNDER CERTAINLY
POSSIBLE AT TIMES...THOUGH COVERAGE OF THE PCPN SUGGESTS MUCH OF
THE PCPN WL BE JUST SHOWERS.

UPR SYSTEM WL EVENTUALLY CROSS THE AREA MID-WK...OR GET SHUNTED S
OF THE AREA AS UPR FLOW TEMPORARILY GETS SOMEWHAT SPLIT AND UPR
ANTICYCLONE DEVELOPS IN THE LAKE WINNIPEG RGN.

IT/S ALWAYS AN IFFY PROPOSITION TO TRY AND READ TOO MUCH INTO THE
LATER PERIOD FCSTS FM THE MED RANGE MODELS. BUT IF PATTERN EVLOVES
AS NOW EXPECTED...UPR RIDGE COULD REMAIN LOCKED IN PLACE FM THE
NRN PLAINS INTO SRN CANADA THROUGH THE FOLLOWING WEEKEND...WHICH
IS THE MEMORIAL DAY HOLIDAY WEEKEND. THAT WOULD ALLOW A DRY
CANADIAN ANTICYCLONE TO DOMINATE THE OUR WX FOR THE ENTIRE WEEKEND
AS IT SLOWLY DRIFTS SE FM HUDSON BAY INTO THE LOWER GREAT LAKES
RGN...RESULTING IN DRY WX...PLEASANT TEMPS...AND PLENTY OF
SUNSHINE.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 700 PM CDT FRI MAY 17 2013

OCNL MVFR CIGS OVERNIGHT AS MODERATELY MOIST EASTERLY FLOW
PERSISTS AND REMNANTS OF MN AFTERNOON CONVECTION MOVES INTO AREA.
IN ADDITION...AREAS OF FOG MAY ALSO DEVELOP. BEST CHANCE FOR
SHOWERS SHIFTS NORTH LATER TONIGHT AND SATURDAY.

&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....ECKBERG
LONG TERM......SKOWRONSKI
AVIATION.......JKL