Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KGRB 171910

Area Forecast Discussion
National Weather Service Green Bay WI
210 PM CDT Sat Mar 17 2018

Forecast discussion for routine afternoon forecast issuance

Issued at 210 PM CDT Sat Mar 17 2018

Quiet weather will continue through the rest of the weekend and the
upcoming work week.

The large scale flow across North America is split in the west,
then consolidates into a deep trough over southeast Canada. The
trend during the period will be for the pattern to reverse, with
the flow out west splitting while the flow to the east
consolidates. The forecast area has been near a col between the
main branches of the westerlies, and despite the expected
reversal of the pattern, is likely to remain so. The dominant
weather feature will be a sprawling anticyclone ridging south
from the Hudson Bay region. That will continue to shunt
significant precipitation producing cyclones south of the area,
and result in little if any precipitation until until possibly
late in the period. After another mild day tomorrow, temperatures
will return to near or a little below seasonal normals for the
rest of the period.

.SHORT TERM...Tonight and Sunday
Issued at 210 PM CDT Sat Mar 17 2018

High pressure dominated the weather pattern across the region this
afternoon. Temperatures were in the 40s, except 50 at Waupaca,
away from the bay and lake. Afternoon relative humidity readings
were from 10 percent to 25 percent away from the lake. In matter
of fact, the temperature dewpoint spread reached 50 degrees at
Land O` Lakes, something you typically see in the southwestern
United States.

For tonight, a few mid clouds may clip portions of far northeast
Wisconsin for a few hours late this afternoon into the early
evening hours. Otherwise, clear skies will prevail. With light
winds and clear skies, lowered minimum temperatures a few degrees
most places, and several degrees at our typical cold spots across
the north that still have snow cover.

For Sunday, it will be another mild day for most, except for
Door County where north/northeast winds off the bay/lake will
keep temperatues in the 30s to around 40. A back door cold front
will move across the remainder of northeast Wisconsin Sunday
afternoon, thus by sunset it will not feel warm from the Fox
Valley east to the lake. The colder air will not work into central
Wisconsin until early evening. Leaned toward the warmer guidance
across central and north-central Wisconsin, and stayed closed to
guidance for Door County. A blend of the warmer mav and colder met
guidance was used for the Fox Valley east to the lake.

.LONG TERM...Sunday Night Through Saturday
Issued at 210 PM CDT Sat Mar 17 2018

Colder air associated with the Hudson Bay high will continue to
surge into the area Sunday night. Flow across the Great Lakes
would normally favor some flurries. But the air/water temperature
differences will initially be modest, and by the time colder air
arrives aloft the air will be increasingly dry.

A weak northern stream shortwave peeling off into the southern
stream may generate some light precipitation across the far west
Tuesday night into Wednesday. Just reflected this with a chance
of flurries for now.

The medium range guidance continues to suggest a strong southern
stream cyclone heading east across the Plains late in the week or
next weekend will track farther north than its predecessors, and
bring significant precipitation to the area. There has been some
run to run consistency in this idea. But given the likelihood of
strong high pressure still residing near Hudson Bay and feeding
dry air into the area, prefer to downplay the system for now.
For the most part, capped PoPs in the chance category.

.AVIATION...for 18Z TAF Issuance
Issued at 1100 AM CDT Sat Mar 17 2018

VFR conditions should continue into Sunday afternoon. Two features
to watch that will impact wind speeds and directions over the next
24 to 36 hours. For this afternoon, lake breeze expected to
develop along the Lake Michigan shoreline and then move inland
late this afternoon and this evening. Still some uncertainty if
the lake breeze would make it to KATW/KGRB although have included
this scenario in the 18z taf issuance. The other event will occur
on Sunday as a backdoor cold front drops southward across
northeast Wisconsin. These fronts typically race down the Bay of
Green Bay and the shoreline of Lake Michigan due to the colder
waters, or in this case the ice covered bay, and will reach
KATW/KGRB/KMTW before reaching KAUW/KCWA. Expected the front to
reach KGRB/KATW/KMTW between 18z and 21z Sunday. There should be
a sudden shift and increase in winds behind this front. The front
should reach KRHI around 18z and KAUW/KCWA around 21z Sunday.



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