Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 190543
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
143 AM EDT Sun Mar 19 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 319 PM EDT Sat Mar 18 2017

Precipitation will exit the area by early tonight. Sunday will be
dry with persistent clouds. Precipitation returns to the forecast
Sunday night into Monday. The rest of the week looks dry with
seasonal temperatures. However Thursday night through Saturday looks
milder and wet with highs in the 50s.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 319 PM EDT Sat Mar 18 2017

Satellite imagery shows warming cloud tops with strong subsidence
aloft overspreading the area. Already weak radar returns continue to
diminish over the southeastern forecast area. Thus, little if any
additional precipitation is currently expected. Have a slight chance
mentioned for our eastern zones this evening.

There is small possibility for brief clearing of our overcast skies
early Sunday morning. However, this is very uncertain and more
likely we will see extensive low cloudiness persisting for most of
the the day.

No real change in thinking regarding rain Sunday night into Monday.
Rain should fall mainly between midnight and early Monday afternoon,
with precipitation totals rather light at a tenth of an inch or
less.

.LONG TERM...(Tuesday through Saturday)
Issued at 319 PM EDT Sat Mar 18 2017

The long term period will start off with a very large high
pressure system tracking out of the Canadian Prairies and into
Michigan. This fair weather system will become centered over the
state on Wednesday. With a low level northeast flow ahead of this
system...a shallow cool and dry airmass will filter in from
Ontario. This will support a cooling trend with temperatures
ending up well below normal for Wednesday.

Warm air advection develops on the backside of the departing high
pressure system for Thursday.  The temperature will start to
rebound...but moisture will be on the increase.  By Thursday night
some precipitation will be moving in from the southwest. Forecast
soundings suggest that if any snow/mix falls that it will not last
long as thermal profile largely remains above freezing. Although it
is worth noting that the new High Res Euro is stalling the surface
front over the CWA on Friday...with the main impact from that being
perhaps a longer period of wintry precipitation for northern zones.
At this point surface temperatures are shown by all models to be
mostly above freezing. Thus it appears that this will be mostly a
rain event.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 143 AM EDT Sun Mar 19 2017

Conditions are largely MVFR through the 06z hour with exception to
TAF sites through interior sections of the state. Enough low level
moisture is present that low clouds have been/will result in VFR
cigs for a few hours. Though vsbys may drop slightly (4SM-6SM) at
interior sites, fog isn`t expected to be much of a hindrance.

Further west, drier air is trying to work its way in. IR SAT images
show clouds breaking over Lake Michigan. This may be enough to
result in gradual improvement for KMKG/KGRR through the morning
and therefore I was a bit more optimistic with cigs. Winds will
remain pretty light at all sites- less than 10 kts.

VFR conditions are expected Sunday afternoon into Sunday night.

&&

.MARINE...
Issued at 959 PM EDT Sat Mar 18 2017

Based on the latest observational data the winds and waves are now
below SCA criteria across the near shore so I expunged it.


&&

.HYDROLOGY...
Issued at 1047 AM EDT Sat Mar 18 2017

River levels are running around normal to a little below normal.
With less than a half inch of precipitation expected through this
weekend and then no additional precipitation until Friday, no
flooding is expected across the area into next weekend. The
precipitation next weekend may be enough to push river levels up,
but they should remain below bank full.

&&

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

$$

SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...MJS
AVIATION...JAM
HYDROLOGY...63
MARINE...WDM



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