Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 170823
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
323 AM CDT Tue Oct 17 2017

Forecast discussion for routine morning forecast issuance

.SYNOPSIS...
Issued at 321 AM CDT Tue Oct 17 2017

Mild, quiet mid-autumn weather to continue for the rest of the
week.

Relatively low amplitude large scale flow is in place across
North America, with the main westerlies pretty far north for this
time of year--primarily across southern Canada. The pattern will
gain some amplitude during the week, with a longwave trough
forming near the West Coast and downstream ridging developing mid-
continent. That pattern will likely be be short-lived, as the
development of a much stronger trough out near 160W will result in
a transition to ridging near the West Coast, and troughing over
the Great Lakes region by the end of the period.

Temperatures 10 to 15 F degrees above normal are expected into the
upcoming weekend, then readings will drop back close to normal by
early next week. Normal precipitation for a week at this time of
year is down to a little over 1/2 inch. In addition, we`ve
entered the time of year where receiving significant precipitation
requires a direct influx of Gulf moisture. Dry air and a lack of
dynamics will result in dry weather into the weekend. The best
chance for rain will be with a frontal system crossing the area
this weekend, but that system seems unlikely to bring significant
rains, so amounts are likely to end up below normal for the
period.
&&

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 321 AM CDT Tue Oct 17 2017

Quiet weather is expected as the main westerlies remain to the
north. Edged max temperatures a little above the broad-based
guidance to account for the very mild air mass flowing into the
region. Mins are a little trickier as any areas that decouple
could have temperatures drop a little more than depicted on the
guidance. Edged the typical cool spots down a little to account
for this, but that still left mins well above normal. Rather windy
conditions are expected by Wednesday afternoon as the gradient
tightens ahead of a cyclone tracking across southern Canada.

.LONG TERM...Wednesday Night Through Monday
Issued at 321 AM CDT Tue Oct 17 2017

500mb ridge across the eastern United States will bring above normal
temperatures to the region into the latter half of the weekend. High
temperatures on Friday and Saturday could reach the 70s at some spots.
The normal high temperature for this time of year is in the middle
to upper 50s.

Some significant timing differences with the cold front and the
arrival of rain across the area this weekend. The GFS/Canadian
models were quicker and would bring rain to the area Saturday
afternoon and Saturday night with a lingering chance Sunday
morning. The ECMWF was about to 12 to 18 hours slower and would
bring rain to the area later Saturday night into Sunday. Took a
blend of the model guidance for now until timing differences get
resolved. Perusal of the convective parameters would indicate
there is a slight chance of a thunderstorm with the passage of the
cold front. Severe weather is not expected. Temperatures return
close to or slightly below normal early next week.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 321 AM CDT Tue Oct 17 2017

With just cirrus passing through, the main aviation concern will
be LLWS. The ongoing LLWS will ease this morning as the gradient
slackens. But another round will develop tonight into Wednesday as
low-level flow increases from the south ahead of the cyclone
tracking east across southern Canada.
&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......Eckberg
AVIATION.......Skowronski



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