Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 231503

Area Forecast Discussion
National Weather Service Grand Rapids MI
1103 AM EDT Sun Oct 23 2016


Issued at 330 AM EDT Sun Oct 23 2016

After mild readings in the 60s today, temperatures will average near
to a bit below normal over the coming week. The main weather maker
this week will be a low pressure system that brings a widespread
cool rain on Wednesday and Thursday.

A weak low pressure system tracking across michigan late this
afternoon and evening will bring some light showers to areas north
of Interstate 96.


.SHORT TERM...(Today through Tuesday)
Issued at 330 AM EDT Sun Oct 23 2016

Swift northwest flow aloft will send a compact vort max currently
near Lake Winnipeg across nrn MN/WI today then across central lower
MI by later today and early this evening. Scattered rain showers
associated with this feature will occur near and north of the vort
track, along and north of I-96, from roughly 21Z-03Z. Rainfall
amounts are expected to be light; generally a tenth of an inch or

Warm advection and considerable sunshine preceding this feature
today will lead to mild temperatures, particularly south of I-96
where H8 temps close to 10C try to nudge in via southwest winds
ahead of apchg sfc low tracking from central WI toward Detroit.
Mildest temperatures are expected near and south of I-94, where some
highs around 70 seem plausible.

Brief period of cold advection/cyclonic northwest flow tonight into
Monday morning should lead to clouds and perhaps a few sprinkles.
Delta Ts support some lake effect, but moisture looks too shallow to
support any measurable precipitation.

Confidence is low as to extent and timing of potential clearing on
Monday. Arrival of anticyclonic flow/subsidence should in theory
bring decreasing clouds, but typically this time of year it does not
fully clear until the sfc ridge axis arrives. That does not occur
until later Monday night. High clouds will bring increasing clouds
on Tuesday as system beings organizing in the central plains.

.LONG TERM...(Tuesday night through Saturday)
Issued at 330 AM EDT Sun Oct 23 2016

The main focus of the long term is the evolution of a low as it
moves from the Plains across the Great Lakes.  The ecmwf continues
to show the best continuity. The 00z gfs has come back in line with
the ecmwf and doesn`t show the low taking a turn to the south

Looks like we`ll see increasing clouds Tuesday night as rain
develops in the warm advection pattern ahead of the low from Iowa
into western Wisconsin. The low will continue to deepen as it moves
east due to continued development of the upper trough. Short waves
were noted digging into the back side of the trough over the Upper
Mississippi Valley as it moves east. At this time the track of the
low still looks like it will cross the central CWA Thursday. We`ll
see rain chances increase Wednesday. As the rain falls into
initially drier air, we`ll see temps remain mostly in the 40s
Wednesday. Combined with increasing winds, Wednesday looks like a
raw day. A half inch to inch of rain looks reasonable for this storm
as it moves across the state.

Conditions will improve Thursday as the low moves east. A slow
warming trend will begin Friday and continue into the weekend.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 747 AM EDT Sun Oct 23 2016

VFR conditions will prevail today and tonight. CLR skies this
morning will trend toward sct-bkn clouds around 4000 ft from
north to south later today and tonight. A few showers may impact
MKG, GRR and LAN after 21Z, but little or no significant vsby
impacts are expected.

Shifting winds will likely impact runway operations/orientations
later tonight and this evening. Today the winds will be out of the
southwest at around 10 knots, although a bit stronger/gustier
this afternoon at AZO, BTL and JXN. The passage of a cold front
from north to south will bring a wind shift to northerly toward
or just after 00z tonight. See TAFs for more specific timing of
the expected wind shift.


Issued at 1103 AM EDT Sun Oct 23 2016

Will go ahead and issue a small craft advisory which will go into
affect late this evening. Northerly winds behind the cold front
and cold advection will create rough waters. There will be a
period where winds will approach 30 knots overnight.

As high pressure begins to build into the region later Monday,
these winds will diminish below 20 knots. Will have a 2 PM Monday
ending time to the advisory.


Issued at 130 PM EDT Sat Oct 22 2016

Streamflow is currently above normal for this time of year at several
gauges across the Grand and Kalamazoo River basins. However, river
levels are either falling or steady. There are currently no
significant hydro concerns, with quiet weather through early next

Widespread rain looks increasingly likely during the Wednesday-
Thursday time frame, with over 0.50 inches possible. Confidence in
rainfall amounts remains low at this time. In general, river rises
are possible late next week into next weekend.


LM...Small Craft Advisory from 10 PM this evening to 2 PM EDT Monday
     for LMZ844>849.



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