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000
FXUS63 KGRB 162004
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
304 PM CDT THU MAY 16 2013

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SYNOPSIS...
ISSUED AT 258 PM CDT THU MAY 16 2013

MULTI-BRANCH MAINLY WLY FLOW ACRS NOAM ATTM WL GRADUALLY AMPLIFY
AS BROAD UPR TROF FORMS OVER THE ROCKIES AND WRN PLAINS DURING
THE WEEKEND. THE ENERGY THAT INITIALLY FORMS THE UPR TROF WL SHIFT
EWD ACRS THE GREAT LAKES RGN EARLY NEXT WEEK...AS ADDITIONAL
ENERGY DROPS DOWN THE WEST COAST AND REPLACES IT. THE RESULT WL BE
THAT BY THE LATTER PART OF NEXT WEEK...UPR PATTERN WL BE FAIRLY
AMPLIFIED...WITH TROFS OVER THE NWRN CONUS AND SERN CANADA/NEW
ENGLAND AND A SHARP RIDGE IN BETWEEN OVER THE NRN PLAINS/CANADIAN
PRAIRIES.

THE UPR PATTERN DOESN/T REALLY FAVOR A SIG DEPARTURE FROM NORMAL
TEMPS. WL PROBABLY END UP WITH DAY TO DAY VARIATIONS MAINLY DUE
TO CLDS/PCPN. UPR SYSTEM CROSSING THE AREA WL LIKELY RESULT IN
ABV NORMAL PCPN FOR THE PERIOD...THOUGH TIMING OF WHEN THE RAINS
WL OCCUR STILL TOUGH TO PIN DOWN.
&&

.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 258 PM CDT THU MAY 16 2013

MAIN CONCERN FOR LATE TONIGHT AND FRIDAY WILL BE LOCATION OF
A BAND OF SHOWERS MOVING ACROSS THE STATE (SOME THUNDER WEST).
DIFFERENCES IN THE MODELS ON WHERE THE HEAVIEST BAND OF
PRECIPITATION WILL SET UP WITH CANADIAN FURTHER SOUTH AND
THE GFS/WRF FURTHER NORTH. THE GFS/WRF SEEMED TO HAVE THE BEST
HANDLE ON PRECIPITATION THIS AFTERNOON ACROSS THE DAKOTAS. 35 TO 40
KNOT LOW LEVEL JET IS EXPECTED TO DEVELOP THIS EVENING ACROSS THE
DAKOTAS WHICH WILL AID IN THE DEVELOPMENT OF CLUSTERS OF SHOWERS
AND THUNDERSTORMS ACROSS THE PLAINS. THIS CLUSTER WILL WORK
EASTWARD INTO WISCONSIN LATE TONIGHT AND MOVE ACROSS THE AREA ON
FRIDAY. WELL DEFINED SWIRL ALSO NOTED ON RADAR AS WELL TO HELP
FOCUS PRECIPITATION. INCREASING DRY SOUTHEAST FLOW MAY LOWER
PRECIPITATION TOTALS ACROSS THE SOUTHEAST ON FRIDAY. LOOKED
AT THE CONVECTIVE PARAMETERS AND THEY ALL INDICATED THUNDERSTORMS
WOULD BE CONFINED WEST OF THE AREA. THIS SEEMED REASONABLE AS
PRECIPITATION WILL BE RUNNING INTO A DRIER AND MORE STABLE AIR
MASS ACROSS OUR FORECAST AREA.

DID NOT STRAY FAR FROM GUIDANCE FOR MIN...EXCEPT FOR A FEW DEGREES
COLDER ACROSS THE FAR NORTHEAST WHERE CLOUDS WILL BE THE LAST TO
ARRIVE LATER TONIGHT. MAX TEMPERATURES DIFFICULT ON FRIDAY. IF
WRF/GFS ARE CORRECT...TEMPERATURES ACROSS THE NORTH MAY NOT GET
OUT OF THE LOW TO MIDDLE 50S DUE TO CLOUD COVER...RAIN AND EAST
WIND. TEMPERATURES MAY REACH THE LOWER TO MIDDLE 60S ACROSS THE
FAR SOUTH...AWAY FROM LAKE WINNEBAGO AND LAKE MICHIGAN.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 258 PM CDT THU MAY 16 2013

MAIN FCST CONCERN WITH THIS PART OF THE FCST IS THE TIMING OF THE
PCPN. MAIN FRONTAL BOUNDARY WL SET UP TO OUR S...LEADING TO A
PROLONGED PERIOD OF ELY THEN SELY FLOW. MEANWHILE AT UPPER
LEVELS...RIDGING WL INITIALLY BUILD ACRS THE FCST AREA...THEN UPR
TROF WL APPROACH FM THE W.

PCPN CHCS THIS WEEKEND ARE THE MOST PROBLEMATIC...AS SOME ISENT
LIFT WL BE OCCURRING ACRS THE AREA. BUT SELY FLOW OUT OF RETREATING
SFC RIDGE DOES NOT FAVOR A STG INFLUX OF MOISTURE INTO THE AREA.
AND UPR HEIGHTS WL BE RISING AND BECOMING MORE ANTICYCLONIC WITH
TIME. DECIDED TO KEEP POPS GOING FRI NGT...WITH GREATEST CHC UP N.
THEN STUCK WITH A LULL IN THE PCPN LATER SAT INTO SAT NGT...ESP
OVER THE SE PART OF THE FCST AREA. ANOTHER ROUND OF PCPN MAY WORK
INTO THE W SUN. KEPT CHC POPS THERE...BUT PULLED BACK ON POPS IN
THE E AS UPR RIDGE WL PROBABLY STILL BE DOMINATING THERE. BEST CHC
OF PCPN WL COME EARLY NEXT WK AS MAIN UPR SYSTEM CROSSES THE AREA.

TEMPS SAT WL BE HELD BACK BY THE ELY COMPONENT TO THE WIND.
TRIMMED MAX TEMPS AT THE LAKESHORE. WENT WITH BLEND OF BEST
PERFORMING GUID FOR INLAND AREAS SAT. THE SAME BLEND YIELDED MAX
TEMPS REACHING THE LOWER 80S IN MANY AREAS SUN. THAT JUST SEEMED
TOO WARM...SO OPTED TO STAY CLOSER TO PREV FCST.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 258 PM CDT THU MAY 16 2013

VFR CONDITIONS WILL CONTINUE INTO FRIDAY MORNING. SOME
MVFR CIGS ARE POSSIBLE LATE FRIDAY MORNING INTO FRIDAY AFTERNOON
NORTH AND WEST OF THE FOX VALLEY AS A CLUSTER OF SHOWERS MOVE ACROSS
THE STATE.
&&

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

$$

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