Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 221148
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
648 AM EST Wed Nov 22 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 324 AM EST Wed Nov 22 2017

Fairly quiet weather is forecast through the holiday travel period.
No major weather systems will affect the area through the upcoming
weekend. Temperatures will be on the cool side of normal today and
on Thanksgiving but will warm back to above normal on Friday. Highs
will be in the 30s today and Thursday but warm well into the 40s,
if not into the 50s on Friday.

&&

.SHORT TERM...(Today through Friday)
Issued at 324 AM EST Wed Nov 22 2017

No major concerns through Friday, with mainly dry weather forecast.
The upper pattern will feature zonal flow with a weak shortwave
moving through our area early on Thanksgiving Day. Another, stronger
shortwave trough will approach late in the day on Friday.

As for precipitation, lake effect snow showers or flurries will wind
down today. Have some flurries mentioned this morning, but overall
the lake effect has been underwhelming. Delta T`s at the present
time are around 20C. The instability is offset however by a lack of
moisture depth. The upper trough shifting east is not helping it
either. Bottom line, lake effect will dwindle through the course of
the morning hours.

Next chance for precipitation is with a burst of warm air advection
late tonight and into Thanksgiving morning. There will be some lake
enhancement to the precipitation with Delta T`s in the lower to
middle teens through midday on Thanksgiving. Best chances for some
light snow will be in the northwest CWA, north of Muskegon and west
of Big Rapids. Models are not bullish on QPF, so only have small
chance pops in the forecast up there. Would not be surprised though
to see a few hours of light snow Thanksgiving morning. Any
accumulations would be light, on the order of a dusting.

Dry weather is forecast from Thanksgiving afternoon through Friday.
It appears precipitation with the next front should hold off through
the day on Friday and not arrive until Friday evening/night.

.LONG TERM...(Friday night through Tuesday)
Issued at 324 AM EST Wed Nov 22 2017

A fairly uneventful and mild long term is expected by late November
standards. We are not looking at any appreciable snow through early
next week. Most of the period actually looks dry.

The best chance for precipitation looks to come right at the
beginning of the long term period on Fri night. A fairly decent
upper wave and associated sfc low will traverse the country just
north of the U.S./Canadian border. Much of the pcpn will be across
the nrn portion of the state closer to the upper wave. The pcpn with
the system will be mainly rain with plenty of mild air out ahead of
it. Rainfall amounts do not look impressive with a lack of a
connection to the Gulf.

Some of the lingering pcpn may fall as some snow/lake effect as
cooler air comes in on Sat into Sat night. This does not looks to be
of significance as the upper wave remains mainly north of the area,
with just a quick glancing blow of the colder air. This should move
out by Sun morning.

Drier conditions with increasingly mild temperatures can then be
expected through early next week. Upper ridging builds in, and a
solid SW flow in the lower levels will bring in warmer air. We could
be looking at another day or two of 50+ degrees toward Tuesday of
next week. There is a small chance of rain on Tue as the next system
approaches the area. We believe for now that the rain will hold off
until after next Tue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 648 AM EST Wed Nov 22 2017

VFR weather is expected the next 24 hours. Ceilings of 3,000-4,000ft
are forecast today, lifting to around 8,000ft tonight. Winds will
be less than 15 knots through the period, with northwest winds
this morning, veering to the southwest this afternoon.

&&

.MARINE...
Issued at 324 AM EST Wed Nov 22 2017

It is going to take a bit of time yet for the lake to settle down
after the wind of the last 24-36 hours. Therefore have extended the
Small Craft Advisory through the course of the morning hours. The
last observation from the mid lake buoy was 6 feet. Expecting to
have 4 footers at least into the 9am to 10am time frame, so extended
the SCA through 11am.

The respite is short lived as another SCA looks likely in a
strengthening southwest flow late tonight and on Thanksgiving. 20-30
knot winds and waves of 4 to 6 feet look likely. Wind and waves ramp
up once again for Friday through Saturday.


&&

.HYDROLOGY...
Issued at 100 PM EST Tue Nov 21 2017

Several rivers remain at advisory/action stage level as runoff
continues from rain that fell over the weekend. Water levels in
these and other rivers will remain fairly steady or slowly fall
through the end of the week. Rain and snow showers today and tonight
will only provide light amounts of precipitation, and will not have
an impact on water levels in rivers, creeks and streams. Additional
flooding is not expected.

A few more rounds of light rain/snow are expected through the end of
the week, but should not have a significant impacts on river levels.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 11 AM EST this morning for LMZ844>849.

&&

$$

SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...NJJ
AVIATION...Duke
HYDROLOGY...HLO
MARINE...Duke



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