Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181450
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1050 AM EDT Wed Oct 18 2017

LATEST UPDATE...
Hydro

.SYNOPSIS...
Issued at 313 AM EDT Wed Oct 18 2017

A large area of high pressure over the Central Appalachians will
dominate our weather pattern over the next few days. This system
will act to keep our weather dry with relatively warm and
breezy conditions continuing. A weakening cold front moves in
from the northwest...but this system dissipates over the area on
Thursday.

&&

.SHORT TERM...(Today through Friday)
Issued at 313 AM EDT Wed Oct 18 2017

Models are in decent agreement in showing the cold front currently
in the Upper MS Valley to track southeast today and into the
region tonight. It will be weakening as it moves in and should
dissipate over the area on Thursday. The Gulf is cut off and this
feature will be lacking moisture. Thus no rain is in the forecast.
What cloud cover is associated with this front is mainly mid to
upper level cloudiness.

Warm condition will prevail today a the low level thermal ridge
moves in. Based on the 925 temperature values...some 70s look
possible. Deeper mixing today will also support gusty wind
conditions. With mixing heights reaching into the 20 to 30 knot
winds...windy conditions look likely...especially the warmest part
of the day.

Less wind is forecasted for Thursday. The pressure gradient
weakens as a result of the front dissipating over the area. Warm
air advection resumes for Friday. Well above normal temperatures
will continue.

.LONG TERM...(Friday night through Tuesday)
Issued at 313 AM EDT Wed Oct 18 2017

Some changes are coming to the forecast, especially late in the
period.

High pressure over the southeast US will continue to bring warm air
north through early Sunday. Highs in the 70s are expected Saturday
and upper 60s Sunday. But then a cold front front blows through
Sunday and models continue to show showers along the front. A very
strong short wave coming in behind the front will then begin to
carve out a very high amplitude trough over the Great Lakes early
next week. We`re likely to see the coldest air of the season so far
during this time. H8 temps are progd to fall from 10c Tuesday
morning to -4c by Wednesday morning. Highs Monday will be in the
lower 60s, which will be much cooler than current temps, but still a
couple of degrees above normal. By Tuesday, highs will only be in
the lower to mid 50s. Given the strength of the short wave coming in
next week, showers are likely during this time.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 634 AM EDT Wed Oct 18 2017

The atmosphere will remain relatively dry through the
period...especially in the low levels. Thus the forecast is for
VFR conditions at the TAF sites. A tight pressure gradient will
exist today. As the temperature warms up...this will increase the
mixing height...supporting increasing winds. It looks like gusts
over 20 knots will occur today.


&&

.MARINE...
Issued at 313 AM EDT Wed Oct 18 2017

The pressure gradient tightens up today as a cold front approaches
from the northwest. Ongoing small craft conditions will continue
for most of the region...but gales may develop this afternoon for
the northern couple of zones. The pressure gradient weakens later
tonight...so any gale conditions should diminish under criteria.


&&

.HYDROLOGY...
Issued at 1050 AM EDT Wed Oct 18 2017

We continue to see river levels slowly recede for the most part
after the heavy rain event last weekend. The trend down will
continue through Saturday with dry weather expected through then.

The next rain event for the area beginning as early as Saturday
night and more likely Sunday will bring measurable rain, however it
appears that rain amounts will be limited to a quarter of an inch or
less. This will not cause any appreciable rises on the rivers and
streams. Additional light rainfall is also expected for the first
half of next week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 2 PM EDT this afternoon for LMZ848-
     849.

     Gale Warning from 2 PM this afternoon to 4 AM EDT Thursday for
     LMZ848-849.

     Small Craft Advisory until 4 AM EDT Thursday for LMZ844>847.

&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...04
AVIATION...MJS
HYDROLOGY...NJJ
MARINE...MJS


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