Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 182029
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
329 PM EST Wed Jan 18 2017

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

.SYNOPSIS...
Issued at 329 PM EST Wed Jan 18 2017

Ridging over the Eastern U.S. will continue to support mild
conditions, bringing well above normal temperatures into the Great
Lakes through the weekend. Multiple disturbances passing through
the middle of the country will keep at least limited chances of
precipitation going. Two main rounds come Friday and again by
late Sunday into Monday. Cooler weather is expected to finally
make a comeback through the middle of next week.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 329 PM EST Wed Jan 18 2017

The main event in the short term moves in late Thursday into early
Friday, bringing yet another round of wet weather.

Upper level ridging continues to control the pattern over the
Eastern U.S., while multiple disturbances get pinwheeled out of
the southwest and into the middle of the country. Our main feature
in this timeframe will be a negatively tilted upper level wave
that rotates northeast through the Central Plains.

Rather defined surface troughing extends east from the upper level
wave and brings increasing chances for rainfall by Thursday
night. Despite PWATs being well above normal by January standards,
rainfall amounts may be limited as the wave weakens Friday.
Deep layer moisture is short lived, so I suspect much of the
rainfall to be in a 12 hour period after midnight Thursday.

One side note to this round is the chance that the onset could
mix in with a little sleet or freezing rain well north of Grand
Rapids...mainly around Harrison and Mount Pleasant. Any mixed or
frozen precip should be light and short lived. Temperatures are
expected to rise above freezing through the morning Friday.

.LONG TERM...(Saturday through Wednesday)
Issued at 329 PM EST Wed Jan 18 2017

We expect to see more of the mild and wet weather last through the
long term portion of the forecast through next Wed. It does appear
that we will start to cool off gradually toward the end of the
period.

The weekend is expected to be the warmest period with max temps
likely eclipsing 50 both Sat and Sun for much of the area. Much of
the weekend will be dry, but a chance of light rain will exist. We
will have deep srly flow supplying the warm and moist air mass,
without much of a organized mechanism to focus rain chances. Clouds
will remain plentiful however, limiting the amount of sunshine we
will see.

We will then see a gradual transition to cooler temperatures next
week with continued smaller rain chances through Wed. The srly flow
aloft will transition to a more W/NW flow aloft by Tue. This occurs
as the strong system that stays south of the area Sun/Mon eventually
wraps back over the region. This will begin to tap some of the
cooler air mass over the wrn portion of the continent. The pcpn with
the low will keep the chances in through Wed. Eventually enough
colder air will filter in that snow will become possible late in the
period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1239 PM EST Wed Jan 18 2017

We are looking at another forecast period with IFR and lower
conditions expected most of the time. There is some good hope that
the IFR will finally diminish later Thu morning.

LIFR conditions prevail across most of the terminals early this
afternoon. There has been some slight improvement with temps
warming a couple of degrees, but additional improvement looks to
be limited. We can not rule out a couple of sites going MVFR for a
short time this afternoon. This is due to the low level moisture
remaining in place, and also upstream of the area across Illinois.
Cigs are expected to lower a bit a few hours after sunset as
temps cool a little.

Conditions will likely go down to VLIFR late tonight and
tomorrow morning as winds become a bit lighter. We should be able
to mix out/push out the shallow low level moisture on Thu morning.
We expect all sites to be VFR by 18z Thu.


&&

.MARINE...
Issued at 329 PM EST Wed Jan 18 2017

A small craft advisory continues with winds of 15-25 knots
resulting in waves of 3-5 feet through this evening. Winds are
expected to decrease overnight and into Thursday to 10-15 knots.
Waves will subside to around 1 foot by Thursday afternoon.

Much of the forecast is rather tame with a few rounds of rainfall
possible through the next several days. Waves will generally be
1-2 feet going into the weekend.

&&

.HYDROLOGY...
Issued at 1210 PM EST Wed Jan 18 2017

The Grand River at Robinson Twp is rising after Mon/Tue`s inch of
rain and a continued restriction of waterflow due to ice. Most
other rivers are rising due to the recent rain but seem to have
less notable ice impacts now. Temperatures (and dew points) will
be above 32 degrees for much of the next 7 days, with highs around
50 possible Sat/Sun. Melting river ice should eventually break
up, at which time flooding at Robinson Twp would likely alleviate.
Nonetheless, rivers across the area, especially in the greater
Grand basin and lower Kalamazoo basin, continue to run high due to
above- normal liquid precipitation this month. A quarter to half
inch of rain on Friday won`t make matters much worse, but it won`t
help either. Low-land flooding near riverbanks is occurring at
multiple forecast points, but impacts to property are not too out
of the ordinary. The Maple River near Maple Rapids will approach
Minor Flood Stage this weekend.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 1 AM EST Thursday for LMZ844>849.

&&

$$

SYNOPSIS...JAM
SHORT TERM...JAM
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...CAS
MARINE...JAM



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