Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 180807
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
307 AM EST Sat Feb 18 2017

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 307 AM EST Sat Feb 18 2017

Temperatures today will be very warm and in record territory with
highs in the upper 50s to lower 60s in spots. Unseasonably warm
weather will continue most of not all of the coming week with
highs generally in the 50s. Rain is expected Monday night into
Tuesday and again towards the end of the work week.

&&

.SHORT TERM...(Today through Monday)
Issued at 307 AM EST Sat Feb 18 2017

Very mild temperatures persisting overnight will set the stage for
a very warm Saturday with very good chances for record breaking
high temperatures in spots. Latest available visible satellite
imagery from Friday evening indicated that snowpack over the
northern forecast area was pretty much eliminated. Nearly full sun
yesterday combined with substantial insolation again today will
chip away at frost depths as well.

Other only item of note is the potential for patchy fog Sunday
morning. This is low certainty and unlikely to pose impacts to
travel should it occur.


.LONG TERM...(Monday night through Friday)
Issued at 307 AM EST Sat Feb 18 2017

Well above normal temps will continue through the work week.  Daily
high temps should largely remain in the 50s, which will be roughly
20 degrees above normal.

Good agreement that a cold front will cross the state on Tuesday.
Appears to be a quick hitter that may put down about a quarter inch
of rain Monday night into Tuesday.  This will be a Pacific system
with only marginally cooler air behind it for Tuesday and Tuesday
night.  Another pleasant day on Wed as we will be in between systems.

Thursday and Friday will be slightly cooler as rain returns.  By
then a stationary front should set up over the state with low
pressure riding up from the SW.  Deep SW flow should bring up plenty
of Gulf moisture, so this could be a steady and prolonged rain
maker, especially into Thursday night and Friday.

For winter enthusiasts, it appears this system will finally return
temps back to near normal and the rain should switch to snow Friday
night into next Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1232 AM EST Sat Feb 18 2017

VFR conditions will continue through the next 24 hours. Even so,
there are a couple of aviation concerns. Low level wind shear will
be possible until close to daybreak. Winds near the surface are
only around 10 knots, while they increase rapidly to around 45
knots just 1K ft above the ground. This wind core moves through
quickly, so the LLWS threat should be moving out prior to
daybreak.

The surface southwest winds will remain brisk at 10-15 knots until
late afternoon when they will finally diminish.

Another issue for aviators could be the development of fog toward
midnight Saturday night. Low winds, and high dew points over the
frozen ground could produce fog. Some IFR may develop toward the
end of this TAF period and toward I-96.

&&

.MARINE...
Issued at 307 AM EST Sat Feb 18 2017

Latest WW3 guidance suggested that waveheights will peak in the
next few hours and could briefly approach craft advisory criteria
in some of the southern marine zones. However, this will be short
lived and winds and waves should relax significantly during the
day.

&&

.HYDROLOGY...
Issued at 1141 AM EST Fri Feb 17 2017

Precipitation chances will remain low through Monday across the
region. Area rivers will continue to fall slowly as a result. The
precipitation event late Monday into Tuesday could cause new
rises to develop. Temperatures will remain warm enough to prevent
ice formation.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...JK
AVIATION...JK
HYDROLOGY...MWS
MARINE...TJT



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