Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 231724

Area Forecast Discussion
National Weather Service Green Bay WI
1224 PM CDT SUN OCT 23 2016

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 356 AM CDT Sun Oct 23 2016

The left exit region of a 100kt jet at 300mb is poised to move
across far northern Wisconsin today, while a surface low moves
from near MSP to MKE. The best upper support for rain is in the
far north, while the best low level warm advection and moisture is
to our south. The upper support is more impressive than the low
level dynamics so will limit rain to the northernthird of the
forecast area. Warm advection ahead of the surface cold front
should boost temperatures a few degrees above normal today.

Lake effect clouds may affect northcentral Wisconsin tonight, with
clearing expected elsewhere. Lows should be a few degrees above
normal. Monday should be sunny and pleasant as a surface high
arrives from the west.

.LONG TERM...Monday Night Through Saturday
Issued at 356 AM CDT Sun Oct 23 2016

Main focus for this period will be the strong storm that is
expected to move across the central United States during the
middle of the week.

Like the last few days, models continue to struggle with arrival
of the rain Tuesday into Tuesday night. Latest ECMWF has trended
slower and this seems reasonable with large 1036 mb high across
Ontario. Per coordination with offices to the west, have trimmed
rain chances across the southwest third of the forecast area
Tuesday afternoon and evening. The main brunt of the storm will
affect the area late Tuesday night through Wednesday evening.
850/925mb temperatures and low level critical thickness values
still support a mix of rain and snow Tuesday night and again
Wednesday night across the north. The only other difference
tonight is the ECMWF is tracking the low much farther north than
the last few nights. The gfs was much further south. If the ECMWF
solution is correct, thunder may need to be added Wednesday and
Wednesday afternoon. Since there is much uncertainty in the track
of the storm, held off on adding thunder at this time.

The system moves away from the region on Thursday. Cyclonic
northwest flow aloft noted on the models. Although we have a
lingering chance of rain Thursday morning, later shifts may need
to increase and add a chance during the afternoon. Some instability
showers may develop Thursday afternoon and again possibly on
Friday. Current forecast for Friday is dry at the moment. The
latest ECMWF indicated a more potent system for Saturday, but this
is a new develop from the previous several days, thus will
continue with the blended forecast guidance.

.AVIATION...for 18Z TAF Issuance
Issued at 1224 PM CDT Sun Oct 23 2016

A modest area of low pressure is expected to move from central
Wisconsin east-southeast into Lower MI by this evening. A cold
front will also sweep through the rest of Wisconsin this afternoon
and turn the winds to the north and increase speeds into the 10 to
20 knot range with a few higher gusts. The bulk of light rain
showers across northern Wisconsin is more associated with the
passage of a mid-level shortwave trough over the northern Great
Lakes. This area of precipitation is forecast to come to an by
early evening. An area of high pressure will move into the Upper
Midwest tonight and into the western Great Lakes on Monday. An
influx of drier air will gradually dissipate the clouds later
tonight with a good amount of sunshine on Monday. Cigs could dip
into the MVFR range late this afternoon into the evening hours.
Otherwise, VFR conditions should prevail from later tonight
through Monday.



LONG TERM......Eckberg
AVIATION.......AK is the U.S. government's official web portal to all federal, state and local government web resources and services.