Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 130735
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
235 AM EST Mon Nov 13 2017

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 236 AM EST Mon Nov 13 2017

This week will be warmer than last week but do not expect much in
the way of sunshine. There will be rain Tuesday night into
Wednesday morning. However one of the most powerful and impactful
storm events of the fall is likely this coming weekend. Expect
winds strong enough to cause significant damage, locally heavy
rainfall followed by lake effect snow showers and colder by
Sunday

&&

.SHORT TERM...(Today through Wednesday)
Issued at 236 AM EST Mon Nov 13 2017


I do not expect to much if any sunshine today and I really
question if the clouds can clear tonight. Tuesday the low clouds
should clear out but by then the mid and high clouds from the
next rain event will be heading our way so still not much
sunshine.

We have light fog and dense cloud over the entire area this
morning. Normally with a surface high moving across the area and
the polar jet to our north I would think skies would clear by mid
morning and in fact our IR image loops show the clearing nearly to
the shores of eastern Lake Michigan near Holland as I write this.
However we do not have much wind today or tonight and there is not
much wind even at mid levels. All of the model sounding hold an
inversion over this area into Tuesday morning. I am thinking the
inversion will trap the clouds so I have patchy drizzle and fog
into mid morning then just cloudy today. Temperature may push to
near 40 by mid afternoon.

Tonight if the clouds do not clear we will have lows in the mid
30s since again there will be nearly calm winds most of the night.
If the sky tried to clear fog would quickly form and so it would
end up cloudy that way too.

On Tuesday the sheared out remnant of once closed upper low of
the Pacific Northwest coast comes our way so that will bring
increasing high and mid clouds. So, once the morning low clouds
and fog mix out, we have clouds from the storm heading  our way.
Thus once again not much sunshine.

Tuesday night into Wednesday the upper wave that was sheared out
of the Pacific Northwest by the next upstream system heads across
southern Canada and the northern 1/3 of the CONUS. For us we have
the 300 mb jet axis nearly overhead Wednesday morning. Of course
that generates strong inflow an low levels the 1000/850 moisture
transport is impressive into lower Michigan by midnight Tuesday
night. There is decent isentropic ascent, the condensation
pressure deficits fall to below 10 mb and the the precipitable
water values rise to 90 pct of the all time max for this time of
year. I am confident all areas will see rain between 9 pm Tuesday
and 9 AM Wednesday. This system will have more wind with it so
skies may try to clear later in the day.


.LONG TERM...(Wednesday night through Sunday)
Issued at 236 AM EST Mon Nov 13 2017


The cold front will be through our fcst area by Wednesday evening
and any light lingering pcpn will quickly come to an end as brisk
northwest winds advect a drier airmass in Wednesday night. A high
pressure ridge will build in from the northwest and bring fair
weather with seasonable temperatures Thursday through at least
midday Friday.

Showers will develop Friday afternoon in a southerly flow warm air
advection pattern well out ahead of the approaching low and cold
front. Rain will become more widespread Friday night into
Saturday as this fall storm continues to strengthen.

It will become very windy Saturday as the low continues to
intensify. Very strong nw flow caa will cause rain showers
to change over to snow showers Saturday afternoon and evening.

Breezy conditions will persist Saturday night into Sunday with
scattered snow showers that will taper off to flurries by late
Sunday and Sunday night. Impacts from very strong winds in the form
of scattered power outages are possible Saturday into Saturday
night.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1115 PM EST Sun Nov 12 2017

A mix of mainly MVFR/IFR conditions will improve a bit to mainly
MVFR overnight as low cigs mainly along the I-94 corridor from
KAZO east to KJXN improve a bit overnight. Primarily MVFR
conditions will then continue at all the terminals through mid
morning Monday due to patchy fog.

Conditions will then improve to VFR by late Monday morning as fog
dissipates and cigs improve. VFR conditions will then continue
through Monday evening.


&&

.MARINE...
Issued at 236 AM EST Mon Nov 13 2017

I would think we would need a small craft advisory for Tuesday
into Wednesday as that storm moves into the area. Winds will
increase to 20 to 30 knots over Lake Michigan by Tuesday
afternoon.

&&

.HYDROLOGY...
Issued at 138 PM EST Sun Nov 12 2017

Precipitation totals of 0.2 inches or less Sunday will have little
effect on rivers, which are running near to above normal for mid-
November. Another quarter inch on Wednesday will keep the ground
soggy. A Fall storm system may produce rainfall totals between 0.5
and 1 inch Friday into Saturday, which would cause river levels to
rise again.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...Laurens
AVIATION...Laurens
HYDROLOGY...CAS
MARINE...WDM



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