Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 191749
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1249 PM CDT Thu Oct 19 2017

Updated aviation portion for 18Z TAF issuance

.SYNOPSIS...
Issued at 316 AM CDT Thu Oct 19 2017

Unseasonably warm through Saturday, showers Saturday night and
Sunday, then much cooler next week.

A progressive and very energetic band of westerlies across Canada
and the far northern CONUS will amplify the next several days.
The progression will come to an end next week as the amplification
continues, with a ridge setting up near the West Coast and trough
around 80-90W.

Temperatures 12 to 20 F degrees above normal are expected through
Saturday, then a downward trend will begin. Readings should be
near or perhaps a little below normal by the middle of next week.
The primary opportunities for precipitation will be with a frontal
system crossing the area this weekend and as the large scale upper
trough develops/sharpens over the area next week. Estimating
amounts has become more difficult than in past days due to
uncertainties in the details of the pattern toward the end of the
period, but the best guess is that amounts will end up AOB normal.
&&

.SHORT TERM...Today...Tonight...and Friday
Issued at 316 AM CDT Thu Oct 19 2017

Quiet weather to continue as a series of strong cyclones track
eastward across Canada. Warm and dry air will continue to dominate
the area. Adjusted max/min temperature grids to account for the
recent biases in the guidance (most notably, too cool during the
day). Very dry air flowing into the area in the wake of a cool
front trailing south from one of the Canadian cyclones will
result in low humidities today.

.LONG TERM...Friday Night Through Wednesday
Issued at 316 AM CDT Thu Oct 19 2017

A major shift in the 500mb pattern is expected over the weekend
into next week. The 500mb ridge anchored across the southeast
United States at the beginning of the period will shift east into
the western Atlantic while a ridge builds across the southwest
United States. A new wrinkle in the forecast is that the upper
trough moving across the central United States is expected to
close off by Tuesday. This system could bring unsettled
conditions to the region.

For Friday night, dry conditions will continue as a slow moving
cold moves into the eastern Dakotas by 12z Saturday. The cold
front will continue to move eastward into Minnesota on Saturday.
Models have been consistent in developing showers ahead of the
front on Saturday. Mid level lapse rates are fairly steep, thus
could not rule out a few thunderstorms Saturday afternoon. High
temperatures could still make it into the 70s across northeast
Wisconsin where there may be a few peaks of the sun. The cold
front finally makes it into western Wisconsin Saturday evening,
and to our western counties by 12z Sunday. Latest model guidance
suggest precipitation Saturday night will be along or behind the
front, thus could be a significant period of time with dry
conditions across eastern Wisconsin. The front then moves across
the area Sunday morning, bringing showers to the area. If you have
outdoor activities on Sunday, the rain may linger across northeast
Wisconsin into the early afternoon hours.

Dry weather is then expected Sunday night into Monday morning.
The next system will approach from the northwest Monday afternoon.
bringing the next chance of showers Monday afternoon and Monday
night. Unsettled conditions continue Tuesday. Low confidence on
expected weather conditions on Wednesday depending on where the
closed upper low ends up.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1249 PM CDT Thu Oct 19 2017

VFR conditions are expected to prevail through Friday with clear
skies or just some thin cirrus. The surface pressure gradient
should remain strong enough to prevent fog from developing
tonight so no issues with visibility are expected either. Surface
winds will back and LLWS will occur across central and north
central Wisconsin during the night.
&&

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

$$

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


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