Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 241938
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
238 PM CDT Fri Mar 24 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Saturday
Issued at 238 PM CDT Fri Mar 24 2017

The latest RAP analysis and satellite/radar imagery show an occluded
low pressure system located over the panhandle of Oklahoma early
this afternoon and a shortwave trough moving east over northern
Ontario.  An elongated area of mid-level convergence is occurring
between these two features, which is contributing to the band of
rain currently moving across central and northeast WI.  Behind the
shortwave, high pressure is building southeast over northern
Manitoba, which will drive the band of rain southward towards
central WI through the rest of the afternoon.  Forecast concerns
mainly revolve around precip trends over the next 24 hours.

Tonight...Low pressure will slowly move east across the central
Plains while a strong high pressure system builds southward into
northern WI.  With a stronger push of dry air from the north, the
band of precipitation will get shoved southward through the night,
resulting in the most widespread rain occurring over central and
east-central WI. North-central WI could see some rain persist on the
northern edge of the band early this evening before it pulls out.
But by exiting the north early in the night, this will negate
another chance of freezing rain.  Low temps ranging from the upper
20s in the north to the middle 30s in the south.

Saturday...The low pressure will continue to migrate east into the
central Mississippi Valley.  But as the high retreats, rain will
gradually return northwest from east-central WI in the morning, back
into central and northeast WI in the afternoon. North-central WI
will likely escape the rain, being located in closer proximity to
the dry Canadian high to the north.  With the rain and gusty
northeast winds, eastern WI will mostly likely be a few degrees
colder than locations over central and north-central WI.

.LONG TERM...Saturday Night Through Friday
Issued at 238 PM CDT Fri Mar 24 2017

Long term period starts out active with on-going chances for rain
and freezing pcpn as a surface and upper level low continue the
slow moving journey from Missouri to southern Lake Michigan
through the weekend. A quiet period looks more likely for the
middle of next week.

PoPs expand back into northern Wisconsin Saturday night as the
low moves closer to Wisconsin. Guidance would suggest boundary
layer temperatures falling below freezing in roughly the
northern half of the forecast area. An elevated warm layer is
evident during this time as well. This introduces freezing rain,
and perhaps some sleet, into the forecast through Sunday morning.
If precip timing and cooling temps lined up right, this could
result in ice accumulations around a tenth of an inch north of a
line from about Merrill to Antigo to Wausaukee. At this time
confidence is not high as this once again depends on the exact
timing of when the pcpn moves north and if temperatures get cold
enough. Will let later shift re-evaluate the potential. Any
freezing pcpn would switch back to rain by mid-morning Sunday.

The low moves east of Wisconsin Sunday night into Monday morning.
Another rough of freezing rain/sleet is possible in the far north
Sunday night, but with the bulk of the moisture and energy now to
the east wouldn`t expect more than a hundredth or two of icing to
occur in isolated areas.

Models in good agreement that the system moving out of the
southwest Monday into Tuesday will stay well south of Wisconsin.
By this time there may still be a hint of wrap around precip from
the weekend system through Monday morning. GFS, ECMWF, and
Canadian models all suggest a surface high and mid and upper
level ridge building in Monday afternoon, and will keep the area
dry Tuesday and Wednesday. High temperatures also get a boost
during this time.

For Thursday and Friday, another system moves out of the southwest
similar to the one currently affecting the Upper Midwest. However,
models vary significantly on placement of the low and its main
features. If southern solution pans out wouldn`t expect much pcpn
in the forecast area during this time. Northern solution could
result in a similar event with daytime rain and overnight mixed
precip. Kept with the blended model solution for now until these
details are able to get sorted out a bit better.

Rain and clouds will keep high temperatures within a few degrees
of seasonal normals through the weekend, in the upper 30s and
lower 40s. Highs should warm into the upper 40s and lower 50s next
week.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1129 AM CDT Fri Mar 24 2017

Poor flying conditions are expected over the next 24 hours. The
band of precipitation will gradually slide south this afternoon
and evening. Expect lifr/ifr cigs/vsbys within the band of rain.
Northeast winds will strengthen late this afternoon through
tomorrow morning and become gusty.
&&

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

$$

SHORT TERM.....MPC
LONG TERM......KLB
AVIATION.......MPC



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