000
FXUS63 KGRB 161133
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
633 AM CDT THU MAY 16 2013

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 420 AM CDT THU MAY 16 2013

FORECAST CONCERNS THIS PERIOD ON TEMPS TODAY...THEN PCPN CHANCES
FOR LATE TONIGHT INTO FRIDAY.

ZONAL FLOW CONTINUES OVER AREA THIS PERIOD WITH SFC RIDGE PASSING
EAST THROUGH STATE TODAY. WINDS TO SHIFT TO THE NORTH THAN EAST BY
AFTN...LEADING TO COOLING EFFECT ALONG THE LAKE AND BAY. HOW FAST
AND HOW FAR INLAND THE QUESTION. GIVEN CURRENT MILDER TEMPS AND
WEST FLOW OVER THE EAST...HAVE BROUGHT TEMPS UP A BIT FROM
PREVIOUS FORECAST. COOLING TO WORK EAST THROUGH THE AFTERNOON.
AREA OF MID LEVEL RETURNS...CLOUDS AND FEW SPRINKLES WORKING
THROUGH NORTHERN WI ATTM ASSOCIATED WITH AREA OF WEAK FGEN
FORCING. MODELS AND CURRENT TRENDS POINT TO FURTHER WEAKENING.
WILL CARRY CLOUDS AND MENTION OF SPRINKLES ONLY THROUGH THE EARLY
MORNING HOURS.

HAVE TRENDED THIS FORECAST TOWARDS THE EC AND GEM DUE TO PCPN
TRENDS. BOTH TREND PCPN CHANCES FURTHER SOUTH AND WEST THROUGH DAY
PERIOD FRI...CLOSER TO SHORT WAVE TRACK AND WARM FRONT LIFTING NORTH
THROUGH THE PLAINS. NAM TOO FAST ON BRINGING LLVL JET INTO WI ON
FRI...WHILE GFS HAS TRENDED TOO WET. EAST FLOW OUT OF HIGH
EXPECTED TO CONTINUE BRINGING IN DRIER AND MORE STABLE AIR INTO
CWA...THUS HAVE BACKED OFF ON THUNDER MENTION.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 420 AM CDT THU MAY 16 2013

AN UPPER LEVEL RIDGE OVER THE REGION WILL SHIFT EAST OF WISCONSIN
DURING THE PERIOD AS A TROUGH OVER THE WEST COAST MAKES ITS WAY TO
THE ROCKIES BEFORE SLOWLY CONTINUING TO THE PLAINS. ONCE OVER THE
PLAINS...A CLOSED CIRCULATION DEVELOPS AND IS FORECAST TO SLOWLY
MOVE TOWARD WISCONSIN AND REMAIN JUST TO OUR WEST FOR A WHILE AS
UPPER FLOW GETS BOUND-UP.

THERE WILL BE PLENTY OF CHANCES FOR SHOWERS AND THUNDERSTORMS AS
SHORT WAVES EJECT OUT OF THE WESTERN CONUS TROUGH AND SURFACE LOW
PRESSURE OVER THE PLAINS SLOWLY APPROACHES THE STATE.

AN UPPER SHORT WAVE AND NORTH MOVING WARM FRONT WILL BRING A
CHANCE OF THUNDERSTORMS TO THE AREA FRIDAY NIGHT. NOT TOO SURE
THAT THERE WILL BE CONVECTION ON SATURDAY OR SATURDAY NIGHT WITH THE
FRONT TO THE NORTH AND THE SHORT WAVE WEAKENING AS IT MOVES AWAY
FROM THE AREA...AND THE 00Z ECMWF DOES NOT HAVE ANY QPF. HAVE
MAINLY SLIGHT CHANCES FOR THUNDERSTORMS SATURDAY AND A DRY
FORECAST FOR SATURDAY NIGHT.

HAVE A CHANCE FOR THUNDERSTORMS AGAIN ON SUNDAY AS THE NEXT SHORT
WAVE MOVES TOWARD THE STATE FROM THE SOUTHWEST AND SURFACE FLOW
BECOMES MORE FAVORABLE FOR BRINGING GULF MOISTURE INTO THE REGION.
HAVE KEPT AT LEAST A CHANCE OF THUNDERSTORMS IN THE FORECAST
THROUGH THE END OF THE PERIOD WITH THE UPPER CYCLONE JUST WEST OF
WISCONSIN AND SURFACE LOW PRESSURE IN THE AREA.

TEMPERATURES SHOULD BE ABOVE NORMAL FOR THE EARLY PART OF NEXT
WEEK...WITH THE AREA IN THE WARM SECTOR OF THE SURFACE SYSTEM.
PLENTY OF CLOUDS...AND PRECIPITATION IN THE AREA...WILL BRING A
COOLING TREND WITH TEMPERATURES A LITTLE BELOW NORMAL BY THE MIDDLE
OF THE WEEK.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 611 AM CDT THU MAY 16 2013

VFR CONDITIONS TO PREVAIL THROUGH NEXT 24 HOURS...WITH TRANSIENT
MID AND HIGH CLOUDS FROM STORMS OVER THE PLAINS DRIFTING IN FROM
TIME TO TIME. WINDS WILL SHIFT TO THE NORTH THAN EAST
TODAY.

&&

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

$$

SHORT TERM.....TE
LONG TERM......MG
AVIATION.......TE