Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 170505
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1205 AM EST Fri Feb 17 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 239 PM EST Thu Feb 16 2017

The area is looking at a prolonged dry period from tonight right on
through Monday. Along with this dry period a good deal of sunshine
can be expected each day. We will also see progressively warmer
temperatures through the weekend that will be much above average by
mid-February standards.

The next chance of rain will not come until the Monday night/Tuesday
time frame with a frontal system. Slightly cooler temperatures can
be expected then for mid-week next week.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 239 PM EST Thu Feb 16 2017

No impact weather is expected through the entire short term portion
of the forecast. We are expecting dry conditions with warming
temperatures through the period.

We can not rule out a few flurries this evening, but will not
feature any in the fcst for now. We will be seeing the H850 front
moving through that will be accompanied by a strong temp gradient.
The air at the sfc is quite dry, and moisture is expected to only
make it down to about 6-7k ft.

Warm advection will then be ongoing on Fri through Fri night, with a
weak cold front moving through on Sat. H850 temps will support temps
in the 50s and warmer. A west wind off of Lake Michigan will keep
max temps tempered a bit.

A low well north up in Ontario near James Bay will push the cold
front through Sat afternoon. The colder air will stay well north,
and there will be no moisture associated with this front. Ridging
will move back in Sat night, keeping conditions dry.

.LONG TERM...(Sunday through Thursday)
Issued at 239 PM EST Thu Feb 16 2017

GFS has trended towards the ECMWF with the timing of a northern
stream low bringing a weak front through Monday night into Tuesday.
Precip should be light as the low remains separate from the southern
stream so not much Gulf moisture is drawn north. P-type looks to be
all rain even up north as suggested by thickness tools and forecast
thermal profiles.

The front hangs up near southern Lower Michigan and a weak sfc wave
may form along it on Wednesday. Confidence is low here with large
spread in the ensembles and poor run to run consistency. Did not
make any significant changes to the blended POPS. Left Thursday dry
for now as indications are sfc ridging builds in. Will have to watch
for overrunning precip breaking out late Thursday and there could be
p-type issues up north as there are hints that some cold air is
available via sfc ridging extending into Lower Michigan from an
arctic high centered near Hudson Bay.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1204 AM EST Fri Feb 17 2017

VFR conditions are expected for the bulk of the next 24 hours with
just mid and high clouds over the region. Southerly winds will
increase by mid/late Friday morning and hold around 10 knots into
the evening.

There could be some fog that develops late Friday night as higher
dew points move into the area. Somewhat questionable how this
plays out since we expect the wind will stay up. This may reduce
the amount of fog development, however will put some MVFR in the
LAN TAF after 03Z Friday night for starters.

&&

.MARINE...
Issued at 239 PM EST Thu Feb 16 2017

We expect that much of the foreseeable future will feature sub-
advisory conditions out on the lake. The only caveat to this will be
Friday night as winds aloft will increase some ahead of a wave of
low pressure. These winds should stay aloft with warm air streaming
in over the cooler waters, and not be experienced at the water sfc.


&&

.HYDROLOGY...
Issued at 239 PM EST Thu Feb 16 2017

River streamflows are running near to much above normal for mid
February. Fortunately, river levels are slowly falling in the areas
affected by nuisance flooding last week. The next chance for rain
will be on Tuesday, but amounts do not look significant enough to be
a concern.

&&

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

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...Ostuno
AVIATION...JK
HYDROLOGY...CAS
MARINE...NJJ



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