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000
FXUS63 KGRB 291750
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1250 PM CDT Mon May 29 2023

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Tuesday
Issued at 355 AM CDT Mon May 29 2023

Forecast concerns include low relative humidity/elevated fire
weather conditions, and above normal high temperatures.

The forecast area remained on the southwest periphery of a large
Hudson Bay high pressure system early this morning. A perusal of
last evening`s soundings around the region showed dry air still
in place, with PWATs around 0.50 inch, and an air mass supportive
of dew points in the 30s in our sandy soil areas. MOS guidance
has been terrible with dew points in recent days, and yesterday`s
guidance was roughly 6-7 degress too high at AUW/GRB, and 11-13
degrees at RHI. Have adjusted based on these biases, and by using
a blend of dew points from our Mixed Dew Point tool, NBM and NBM
10th percentile. The low dew points, combined with continued
gradual warming into the 80s (cooler lakeside due to SE winds)
supports relative humidity values of 15 to 25 percent in the
sandy soil regions this afternoon, and again on Tuesday. We have
had a couple more significant fires in recent days, so we plan to
continue issuing Special Weather Statements to highlight very dry
conditions and elevated fire weather concerns through at least
tomorrow.

.LONG TERM...Tuesday Night Through Sunday
Issued at 355 AM CDT Mon May 29 2023

The upper ridge that has been over the Western Great Lakes the
past week or so will move to the east by Tuesday. Southwest upper
flow and a weak surface front that should weaken as it moves into
Wisconsin will bring a chance of mostly diurnally driven showers
and thunderstorms Wednesday afternoon through Friday.

The upper ridge is then forecast to retrogress back into the
Western Great Lakes Saturday and Sunday and probably shut down any
chance of precipitation. The models bring a cold front down from
Canada Monday night or Tuesday with another chance of showers or
thunderstorms.

High upper heights and southerly low level flow will make for
warmer than average temperatures this week. Dewpoints will likely
slowly rise through Thursday or Friday and then slowly fall as
winds bring some drier air in from the northeast.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1237 PM CDT Mon May 29 2023

VFR flying conditions continue through the rest of the day and
through Tuesday. Winds will become mostly calm again tonight
before coming back to around 5 to 8 knots tomorrow. Only clouds in
the area will be occasionally broken high clouds.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM.....Kieckbusch
LONG TERM......RDM
AVIATION.......Uhlmann