Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 160730

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 AM EDT Sun Oct 16 2016

Synopsis/Short Term/Long Term/Marine

Issued at 330 AM EDT Sun Oct 16 2016

It will remain mild by October standards into Tuesday. Highs on
Monday and Tuesday are expected to reach the upper 70s across
Southern Lower Michigan. Showers and thunderstorms will be numerous
this morning before tapering off this afternoon and evening. Another
round of precipitation is expected overnight as a warm front lifts
northward through the state. Precipitation will be confined to
Central and Northern portions of the Lower Peninsula Monday and
Monday night. Cooler weather is expected behind a cold front that
will push through the area on Tuesday. Highs will dip into the 50s
by Thursday and Friday.


.SHORT TERM...(Today through Tuesday)
Issued at 330 AM EDT Sun Oct 16 2016

Strong moisture transport is ongoing into the Great Lakes region at
300am, which is being forced by a 35-40 knot low level jet which is
overhead. The main precipitation event in the short term is
unfolding this morning and should be contained from early this
morning into the midday hours. The low level jet moves east of
Southwest Lower Michigan by 18z which effectively shuts down the
moisture transport. Highest chances for showers and thunderstorms
will be this morning, gradually shifting southward through the
forecast area in conjunction with the movement of best moisture

In terms of instability only working with 500 to maybe 750 J/KG of
CAPE so not expecting anything more than embedded thunderstorms this
morning. No severe weather anticipated. There will be some good
training of cells however in an environment with 1.60 inch PWAT
values which is very high for this time of year. 850mb dew points
are up around +12C is is also formidable for mid October. Bottom
line, some locally heavy rains will slowly be shifting south through
the area between 07z and 18z.

Precipitation tapers off this afternoon and evening as there is
little convergence along the stalled boundary that will be across
the CWA. Later tonight however the low level jet begins to ramp up
once again and we should see some showers and a few storms develop
especially in the northwest toward Ludington late.

Monday and monday night much of the focus should be off to the north
of our forecast area. Do have chance pops for showers and storms in
the forecast across Central Lower Michigan during this time however,
which will be closer to the front. The upper flow during these
periods will be west-southwest with much of the energy translating
in the upper Great Lakes.

Tuesday we have a dry forecast in place but could see the need for a
few showers as the main cold front will be pushing through the
region. Moisture is somewhat limited however.

It will remain mild through the short term with upper 70s in the
forecast across Southern Lower Michigan on Monday and

.LONG TERM...(Tuesday night through Saturday)
Issued at 330 AM EDT Sun Oct 16 2016

Progressively cooler air will move over the region through the end
of the week, becoming quite chilly by the Thursday through Saturday
time frame.  Guidance continues to give us rain chances Wed through
Fri, although there is some uncertainty to this.

A surface boundary is expected to stall over the Ohio Valley by
Wednesday and with zonal flow in the upper levels it is somewhat
questionable how much Gulf moisture makes it this far north.  Low
POPs will remain, but low confidence is also low.  Probably better
chances for rain Thursday into Thursday evening as a deepening upper
trough moves over the Great Lakes, however still wonder if the bulk
of the moisture remains to our south and east. Therefore the highest
POPs will be over the SE CWA.

Even chillier air arrives behind the upper trough into
Friday/Saturday with H8 temps dropping to around 0C.  Seems like a
decent set up for lake effect, but there is poor agreement in the
models, how quickly to bring in a surface ridge. Feel Friday will
see the best chance for widely scattered lake effect rain showers.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 141 AM EDT Sun Oct 16 2016

VFR still covered the region at 05Z, although MVFR was just
upstream over WI, along with areas of showers and thunderstorms.

Expect a downward trend to conditions through the wee hours of the
morning across SW MI. Since the weather is approaching from the
NW, the I-96 TAF sites will lower first. Expecting MVFR to arrive
around 08Z, and continue to lower to IFR around 11Z. The I-94 TAF
sites will lower about 3-5 hours later, through the mid/late
morning hours. Accompanying the lower conditions will be showers
and embedded thunderstorms.

Once the IFR arrives it will likely remain for the remainder of
the day and into Sunday evening. Occasional LIFR is also probable.

The showers and storms are expected to move through, with less of
a risk by mid/late afternoon. However more scattered storms may
redevelop toward I-94 toward midnight.


Issued at 330 AM EDT Sun Oct 16 2016

Decided to keep the SCA going with marginal conditions this morning.
Waves should fall below criteria this morning. The next higher wave
event develops quickly on Monday as southerly flow strengthens. Will
let this advisory expire this morning before starting up the next
one. We may need to issue the next SCA for Monday this afternoon to
give some notice.


Issued at 1146 AM EDT Sat Oct 15 2016

River levels are running above normal for this time of year in the
upper half of the Grand basin, including Hastings, Ionia, and
points upstream. Basin average rainfall amounts approaching one
inch are possible Saturday night through Sunday in a portion of
the area. The typically flood-prone points of tributaries in the
upper half of the Grand River basin may deal with rises to above
bankfull if widespread greater than one inch of rain is received,
but this is not the most likely scenario.


LM...Small Craft Advisory until 11 AM EDT this morning for



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