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FXUS63 KGRR 232358
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
758 PM EDT Tue Oct 23 2018

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Tue Oct 23 2018

Light lake effect precipitation will taper off this evening. High
pressure will bring dry weather for Wednesday and Thursday. The next
chance for some light rain will come on Friday as a weakening system
moves into the plains states. Another low will be developing off the
East Coast of the United States which will push some precipitation
back into the Southern Great Lakes over the weekend. Any
precipitation is expected to be light. Temperatures are expected to
be near normals for this time of year over the course of the next 7
days with highs in the upper 40s to lower 50s and lows in the upper
20s to 30s.

&&

.DISCUSSION...(This evening through next Tuesday)
Issued at 330 PM EDT Tue Oct 23 2018

Lake effect rain showers are occurring across portions of Central
Lower Michigan this afternoon as Delta T's over the lake remain
fairly high. The lake water temperatures are around +12C with 850mb
temperatures of -5C. Delta T's in the upper teens C are more than
enough for precipitation especially with some pre-conditioning off
of Lake Superior in a north-northwest flow. These showers should
wind down this evening as the winds speeds diminishing in the cloud
layer and the winds turn more northerly.

Dry and clear to partly cloudy conditions are expected on Wednesday
and Thursday as a fairly expansive surface high drifts through the
Great Lakes.

The next chance of precipitation will come on Friday as upper
troughing moves our direction out of the plains. We will be located
at the surface in between a weakening low in the plains states and a
deepening low off the east coast. The scenario is usually not a
prolific precipitation producer for us and this time seems no
different. The trend however is toward a deepening Eastern U.S.
trough as we end into the weekend and early next week. Our best
chances for precipitation through the 7 day forecast will be out on
Sunday into Monday as the low moves toward the Eastern Great Lakes.
So, the bottom line is we have some small pops in the forecast from
Friday into Saturday with high pops late in the weekend into early
next week. We have some snow mixing in at times across Central Lower
Michigan especially during the early morning hours. There are some
model discrepancies yet with the Sunday/Monday east coast system in
terms of how close it gets to the our region. At this point it
appears the deeper low will be off the east coast keeping the
heavier precipitation well east of our area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 758 PM EDT Tue Oct 23 2018

VFR weather will continue tonight and Wednesday with just
few to scattered clouds between 3500 and 6000 ft. Winds will be
northerly at only 4-8 kts.

&&

.MARINE...
Issued at 330 PM EDT Tue Oct 23 2018

Shortened the end time of the Small Craft Advisory by a few hours to
200am tonight. The waves should fall off steadily tonight as winds
decrease to around 10 knots and become off shore. A period of lower
waves are expected from Wednesday into Thursday as high pressure
drifts east through the Great Lakes. The fairly calm conditions for
this time of year will continue into Friday. So, after the waves
diminish later tonight the remainder of the week should see waves of
2 feet or less.


&&

.HYDROLOGY...
Issued at 950 AM EDT Tue Oct 23 2018

Rivers levels are near normal to above normal for the time of year,
but continue to fall across the area. There will be some light rain
or snow showers today, mainly along the Lake Michigan shoreline.
Less than a quarter inch of precipitation is expected through the
week and water levels on area rivers should continue to slowly
fall.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 2 AM EDT Wednesday for LMZ844>849.

&&

$$

SYNOPSIS...Duke
DISCUSSION...Duke
AVIATION...Meade
HYDROLOGY...63
MARINE...Duke
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