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000
FXUS63 KGRB 211807
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
107 PM CDT TUE MAY 21 2013

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 351 AM CDT TUE MAY 21 2013

HIGHLY AMPLIFIED/SOMEWHAT BLOCKY FLOW REGIME WL BECOME
ESTABLISHED ACRS THE CONUS DURING THE PERIOD. UPR TROF WAS
CURRENTLY OVER THE NRN PLAINS...WITH RIDGES OVER THE ROCKIES AND
NR THE EAST COAST. ANOTHER UPR LOW WAS DIGGING SWD DOWN THE WEST
COAST. THE PLAINS TROF WL PHASE WITH SOME ENERGY DROPPING SWD FM
THE HUDSON BAY AREA AS IT SLOWLY MIGRATES INTO ERN NOAM. MEANWHILE
BACK W...RIDGE OVER THE ROCKIES WL EXPAND TO EXTEND FM THE SRN
PLAINS...NWD...INTO THE CANADIAN PRAIRIES...WHILE THE UPSTREAM
TROF LINGERS OUT NR THE WEST COAST.

TEMPS WL DROP TO BLO NORMAL LEVELS FOR A FEW DAYS DAYS...THEN
REBOUND THIS WEEKEND AND EARLY NEXT WK. PCPN AMNTS ARE LIKELY TO
BE AOA NORMAL...PRIMARILY DUE TO WHAT FALLS THE NEXT COUPLE DAYS.
&&

.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 351 AM CDT TUE MAY 21 2013

VARIOUS COMMS/EQUIPMENT/CONNECTIVITY ISSUES REALLY THREW SOME
ROADBLOCKS INTO THE THE PROCESS OF TRYING TO PUT TOGETHER THE
FORECAST THIS MORNING. BUT HERE GOES...

BAND OF CONVECTION LIFTG NWD ACRS THE FCST AREA EARLY THIS
MORNING SHOULD EVENTUALLY SLOW AND WEAKEN AS IT APPROACHES THE
DEFORMATION ZONE TO THE N. MEANWHILE AT THE SFC...WEST/EAST
BOUNDARY WHICH LIKELY ORIGINATED AS REMNANTS OF OLD OCCULUSION WL
LINGER ACRS THE N. ONCE THE MORNING RAINS SHIFT NWD...FOCUSED POPS
NR THE BOUNDARY FOR THE REST OF TDA INTO TNGT. CAN/T RULE OUT
ISOLD-SCT CONVECTION DEVELOPING FARTHER S...ESP IF SIG SUNSHINE
OCCURS ACRS THE S LATER TDA. BUT THE MORE WIDESPREAD SHRA/TSRA
SHOULD BE ACRS THE N. SPC TRIMMED THE SLGT RISK OF SVR STORMS TO
MAINLY E-C WI. WHILE SVR STORMS WOULD CERTAINLY BE POSSIBLE IF SIG
CLEARING AND DESTABLIZATION CAN OCCUR...SHEAR WL BE WEAKER THAN
YDA. WL MENTION POSSIBILITY IN THE HWO...BUT RISK SEEMS TOO
LIMITED/CONDITIONAL FOR EXPLICIT INCLUSION IN GRIDS/ZONES AT THIS
POINT.

SFC BOUNDARY WL BEGIN TO SHIFT SWD TNGT. BUT FORCING WL BE FAIRLY
WEAK...SO SHOULD GET SOMEWHAT OF A DECREASING TREND IN THE
CONVECTION AS THE ATM STABILIZES OVERNIGHT.

WHAT SEEMS LIKE THE BEST CHC FOR SIG WIDESPREAD PCPN SHOULD OCCUR
OVER E-C WI WED AS UPR SYSTEM APPROACHES FM THE W. MODELS ALL
SHOWED CONSIDERABLE QG FORCING OVERSPREADING THE AREA DURING THE
DAY. WL START OUT WITH CHC POPS...THEN TAKE THEM TO LIKELY OVER
THE SE PART OF THE FCST AREA BY AFTN. SFC BOUNDARY SHOULD BE WELL
S BY THEN...SO IT WL BE COOLER...AND FOCUS ANY SVR THREAT TO OUR
SE.

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 351 AM CDT TUE MAY 21 2013

A RETURN TO BELOW NORMAL TEMPERATURES ARE EXPECTED THROUGH MUCH
OF THE PERIOD...ESPECIALLY WITH THE NIGHT TIME LOWS AS CANADIAN
HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN.

LOW PRESSURE MOVING ACROSS THE WESTERN GREAT LAKES WILL CONTINUE
TO BRING CHANCES FOR SHOWERS WEDNESDAY NIGHT. THE HIGHEST CHANCES
WILL BE ACROSS THE EAST/LAKESHORE REGION AND WILL TAPER OFF
RAPIDLY AS YOU HEAD NORTHWEST TO VILAS COUNTY. SOME UNCERTAINTY IN
WHERE AXIS OF HEAVY PRECIPITATION WILL OCCUR...THUS LATER FORECAST
MAY NEED TO ADJUST AMOUNTS AND LOCATION OF THE BAND OF HEAVIER
RAINFALL. THE UNSETTLED WEATHER WILL COME TO AN END FROM NORTHWEST
TO SOUTHEAST LATER THURSDAY NIGHT. DID LINGER A SMALL CHANCE OF
SHOWERS FOR EARLY THURSDAY MORNING ALONG THE LAKESHORE. THE
BIGGEST CHANGE ON THURSDAY WILL BE THE CLEARING SKIES AND DROPPING
DEW POINTS. SKIES WILL BECOME SUNNY FROM NORTHWEST TO SOUTHEAST
DURING THE MORNING AND EARLY AFTERNOON. THE AMPLE SUNSHINE WILL
ALLOW FOR DEW POINTS TO DROP INTO THE 20S NORTH AND 30S ALONG THE
LAKESHORE. IT WILL FEEL COOL AS NORTH/NORTHEAST WINDS OF 15 TO 25
MPH CAN BE EXPECTED. TEMPERATURES ALONG THE BAY AND LAKESHORE
ALWAYS TRICKY THIS TIME OF YEAR DEPENDING IF WINDS ARE DUE NORTH
OR HAVE A SLIGHT EASTERLY COMPONENT. DID LOWER MAX TEMPERATURES A
FEW DEGREES ACROSS THE EAST. HIGHS ON THURSDAY WILL BE IN THE
MIDDLE 50S TO AROUND 60 EAST AND VILAS COUNTY... AND IN THE LOWER
TO MIDDLE 60S WEST.

THE COOL DRY AIR MASS...COMBINED WITH CLEAR SKIES AND LIGHT WINDS
WILL ALLOW TEMPERATURES TO PLUMMET BY FRIDAY MORNING. A WIDESPREAD
FROST IS EXPECTED ACROSS THE NORTH WITH SOME OF THE TYPICAL COLDER
LOCATIONS EXPERIENCING A HARD FREEZE FOR A FEW HOURS. AREAS OF
FROST ARE EXPECTED ACROSS CENTRAL AND NORTHEAST WISCONSIN. SINCE
WE ARE NOW WELL INTO THE TYPICAL GROWING SEASON...WILL HIGHLIGHT
IN THE HAZARDOUS WEATHER OUTLOOK AND GRAPHICAST. DESPITE A COOL
START...TEMPERATURES WILL REBOUND INTO THE LOWER TO MIDDLE 60S ON
FRIDAY.

THE MAIN CONCERN FOR NEXT WEEKEND WILL BE POSITION OF THE
CANADIAN HIGH AND SURFACE WARM FRONT WELL SOUTHWEST OF THE STATE.
THE GFS WAS FURTHER NORTH WITH THE FRONT AND ASSOCIATED
PRECIPITATION ON BOTH DAYS THIS WEEKEND. INKLING THAT THE BEST
CHANCE FOR RAIN WOULD BE ACROSS OUR FAR SOUTHWEST LATE FRIDAY
NIGHT INTO SATURDAY AND THE REMAINDER OF THE WEEKEND WOULD BE DRY.
HAVE REMOVED CHANCES FOR RAIN ACROSS THE NORTHEAST TWO THIRDS OF
THE FORECAST AREA AND CONFINED SHOWERS TO THE SOUTHWEST THIRD FOR
BOTH DAYS. IF MODELS COME INTO BETTER AGREEMENT...MAY BE ABLE TO
REMOVE SOME MORE OF THE SLIGHT CHANCES FOR SHOWERS ON ONE OR BOTH
DAYS. EVEN IF THE FURTHER SOUTH SOLUTION DOES VERIFY... HIGH
CLOUDS WILL STREAM ACROSS THE REGION OVER THE WEEKEND FROM TIME TO
TIME. HARD TO DETERMINE AT THIS POINT IF SKY COVER WOULD BE
PARTLY/MOSTLY CLOUDY. BEST CHANCE FOR MOSTLY CLOUDY CONDITIONS
WOULD BE ACROSS THE SOUTHWEST PORTION OF THE AREA. MODEL
DIFFERENCES YIELD TO A LOW CONFIDENCE IN THE MEMORIAL DAY
FORECAST. MADE LITTLE CHANGE TO THIS PERIOD.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 107 PM CDT TUE MAY 21 2013

VARIABLE WEATHER CONDITIONS EXPECTED THIS AFTERNOON
AND TONIGHT AS BANDS OF SHOWERS AND THUNDERSTORMS MOVE ACROSS THE
REGION. CONDITIONS WILL GENERALLY BE VFR EAST OF A MARINETTE TO
SHAWANO TO WAUPACA LINE LINE WITH MVFR CONDITIONS FURTHER WEST.
BRIEF IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS. IN
ADDITION...THERE IS DENSE FOG ALONG THE LAKE MICHIGAN SHORE. IT
WILL PROBABLY STAY JUST EAST OF THE MANITOWOC AND STURGEON BAY
AIRPORTS BUT IT WILL BE CLOSE.
&&

.MARINE...
ISSUED AT 351 AM CDT TUE MAY 21 2013

GUSTY NORTH/NORTHEAST WINDS WEDNESDAY NIGHT AND THURSDAY WILL
CREATE HAZARDOUS CONDITIONS FOR SMALL CRAFT. THE WINDS AND WAVES
WILL GRADUALLY SUBSIDE LATE THURSDAY AFTERNOON AND EVENING. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED WEDNESDAY NIGHT INTO
THURSDAY EVENING.
&&

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

$$

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