Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 131802
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
102 PM CDT Sun May 13 2018

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 307 AM CDT Sun May 13 2018

After a chilly start to Mother`s Day, the rest of the day should
shape up to be fairly nice across the region as temperatures
warm up into the upper 60s to lower 70s away from Lake Michigan.
The warmest temperatures will once again be across the north with
mostly sunny skies, as temperatures across the south will be a bit
cooler given more clouds from a still active frontal boundary to
our south.

The aforementioned frontal boundary becomes active again tonight
and Monday as storms develop over southern Wisconsin and northern
Illinois. While some models do bring some of this activity across
the far southern cwa, the best chances look to be to the south
given the dry air in place across the region. Lows tonight will be
warmer, generally in the upper 40s to lower 50s. Highs Monday will
be notably warmer with highs in the middle to upper 70s with a few
80 degree readings possible.

.LONG TERM...Monday Night Through Saturday
Issued at 307 AM CDT Sun May 13 2018

Surface boundary will remain stuck across northern IL Monday
night into Tuesday. Dry air looks to win out over most of the
area keeping things dry; however, locations south of a Marshfield
to Kewaunee line could get clipped with showers, as they reside
closest to the boundary, best lift, and better moisture.
NAM/GFS/Canadian all showing some heavier rain (along with the
chance of thunder) just to our south or clipping our southern
counties on Tuesday. ECMWF focuses this heavy rain across far
southern WI. Still leaning toward the southern solution on this,
but any northward push of the front would require raising POPs/QPF
for portions of central and east central WI. The boundary sags
south Tuesday night into Thursday as high pressure extends down
from Canada, providing for dry conditions.

Next chance for widespread shower/storm activity across the area
arrives Friday and Saturday, as the flow across the western Great
Lakes turns to the S/SW at the surface and aloft and moisture
increases ahead of an upper trough and cold front. Timing of these
features this far out is of course a challenge and the models have
various solutions, but current model blend of timing has the best
chance for showers and storms arriving Saturday and Saturday
night.

Temps on Tuesday look to be slightly cooler than Monday as temps
aloft drop a little as flow briefly becomes NE. Temps aloft
recover quickly on Wednesday, with 850mb temps climbing to 13-16C.
Should get highs in the upper 70s to lower 80s. Models have 850mb
temps falling back into the 10-13C range for the end of the week
which will keep highs in the lower and middle 70s for most spots.
Much cooler air arrives behind the cold front sometime this
weekend as 850mb tumble into the single digits. Onshore flow
through much of the period will keep cooler temps near Lake
Michigan.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 102 PM CDT Sun May 13 2018

VFR conditions expected this afternoon and evening with light
winds. Some MVFR ceilings are possible south of a ISW to MTW
line late tonight and early Monday. Some fog is also possible
late tonight, mostly near the bay and lake. It would dissipate by
14z if it does materialize. VFR conditions are likely Monday with
just some middle and high clouds.
&&

.FIRE WEATHER...
Issued at 307 AM CDT Sun May 13 2018

Lack of recent rainfall, low relative humidities and warmer
temperatures will produce elevated to near critical fire weather
conditions over central and especially northern WI through the
middle of next week. RH values in the upper teens and 20s are
expected each afternoon. Moisture begins to slowly increase
Wednesday and Thursday. Temperatures will be the warmest on Monday
and Wednesday, with highs in the upper 70s to lower 80s. Winds
are forecast to remain pretty light through the middle of next
week, mainly under 10 mph with a few gusts to 15 mph possible.
&&

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

$$

SHORT TERM.....Kurimski
LONG TERM......Bersch
AVIATION.......RDM
FIRE WEATHER...Bersch



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