National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KGRB 210332
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1032 PM CDT Wed Jun 20 2018

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Thursday
Issued at 316 PM CDT Wed Jun 20 2018

The main forecast concern both for tonight and Thursday to be the
northern extent of precipitation from a system moving across the
central Plains.

The 19Z MSAS surface analysis showed an area of low pressure
located over central IA with a quasi stationary boundary extended
southeastward through central IL. High pressure was situated just
west of Hudson Bay with its southern extent reaching northern
sections of the Great Lakes. Other than a few pesky light showers
that grazed central WI earlier in the day, radar mosaic showed the
main area of showers/thunderstorms over the central
Plains/Midwest.

A nearly vertically-stacked system is forecast to slowly move
southeast near the NE/IA border tonight, while a quasi-stationary
front runs from west-central IA to central IL. Moisture to
continue spinning around this system due to weak frontogenetical
forcing with the northern fringe of light rain showers flirting
with southern sections of the forecast area. Prefer to mention a
minimal pop for parts of central WI, but anticipate bulk of any
rain to remain to our south. Otherwise, high pressure south of
Hudson Bay will send drier air into northeast WI with mostly clear
skies far northeast WI and partly cloudy skies elsewhere. Min
temperatures to range from around 50 degrees far north, middle to
upper 50s south.

The system is progged to continue moving southeast into northern
MO on Thursday, while the high pressure drops south toward Lake
Superior/southern Ontario. The northern edge of the main
precipitation band will continue to try and push into central/
east-central WI, however drier air from the high pressure should
keep the forecast area dry. More clouds south/more sun north
should bring fairly uniform temperatures over the area (away from
Lake MI). Look for readings mainly in the middle to upper 70s,
expect around 70 degrees near the lake.

.LONG TERM...Thursday Night Through Wednesday
Issued at 316 PM CDT Wed Jun 20 2018

Generally dry weather is expected for the rest of this week
through the weekend. The exceptions are late Friday night, when
there is a slight chance for showers in east-central Wisconsin,
and on Sunday when there is a chance for showers and thunderstorms
in central Wisconsin. The slight chance PoP on Friday night is
associated with surface and 500 mb lows moving northeast after
passing through Illinois. The chance for showers and possibly a
few storms on Sunday is due to a cold front passing through the
area from north to south. The next chance for widespread showers
and storms looks to begin Tuesday and continue through Wednesday
with a surface system and mid level trough approaching the area
from the Plains.

Temperatures should not stray far from normal during the period,
with highs mostly in the 70s and lows in the 50s.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1028 PM CDT Wed Jun 20 2018

Although isolated light showers may develop southwest of a line
from ISW-OSH overnight into Thursday, they are expected to stay
south of the TAF sites. Though patchy fog is possible in northern
WI overnight, confidence is too low to mention at the RHI TAF
site. VFR conditions should prevail through the TAF period, with
sct-bkn mid and high-level clouds.

East to northeast winds will increase a bit on Thursday, and
become gusty in the Fox Valley.
&&

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

$$

SHORT TERM.....Kallas
LONG TERM......MG
AVIATION.......Kieckbusch