Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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947
FXUS63 KGRR 152358
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
658 PM EST Sun Jan 15 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 326 PM EST Sun Jan 15 2017

The low pressure system that is producing ice across the Midwest
will move from Texas tonight across Missouri Monday and Lower
Michigan Tuesday. A feed of warmer air aloft will produce a mix of
light snow, freezing rain and rain from late Monday through Tuesday.
Highs will warm from the mid 30s Monday to the lower 50s by
Saturday.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 326 PM EST Sun Jan 15 2017

Forecast concerns deal with the approaching low and chances for pcpn
and the p-type.

The situation that`s going to unfold over the next 36 hours isn`t
the classic type of freezing rain event where we see a strong high
over Ontario feeding cold dry air into the state from the northeast.
In this case the high is in far eastern Quebec and won`t have enough
strength to do that. This means that there is a higher likelihood
that we`ll be able to warm the sfc a bit quicker as the low
approaches from the southwest late Monday.

Forecast soundings on the sref, gfs, nam, show a large amount of dry
air in the lower levels Monday even across the southern cwa. It may
be until 18z or so before pcpn begins and by that time, sfc temps
will be slightly above freezing mitigating the freezing rain threat.
Where we might have an issue is the northeast 6 counties. However,
given the dry air in place, pcpn might not start there until after
22z or even 00z. But, as night approaches, temps will fall and we
should see some freezing rain there. Seems like a headline may be
possible Monday night for the northeast 6 counties but after
collaboration with surrounding offices will not issue yet.

By Tuesday temps will be warm enough everywhere for rain early, but
then change back to mixed rain/snow as colder air works back into
the cwa behind the low.

.LONG TERM...(Wednesday through Sunday)
Issued at 326 PM EST Sun Jan 15 2017

Main weather item of note in the long term period is the mild air
that will be in place the entire time. Forecast highs on Wednesday
are around 40, rise into the 40s for Thursday and are around 50 or
into the 50s for Friday through Sunday. To put that into perspective
normal highs are around the freezing mark, so we will be well above
normal.

A weak upper shortwave trough will be exiting the Great Lakes region
on Wednesday. We may have a lingering rain or snow shower in the
east during the morning. Otherwise we look to be dry for the bulk of
Wednesday and Thursday. Upper heights will be rising with shortwave
ridging working through the area.

More uncertainty shows up deeper into the forecast during the Friday
through Sunday portion in regard to chances for rain. A weak
shortwave may bring us some rain on Friday as it lifts northward.
Deep southerly flow sets up for Saturday and Sunday with our area
just downstream from troughing in the plains. We have low chances
for rain showers much of the Friday through Sunday period on the
order of 20-30 pct. It will likely not be raining all of the time
with Saturday looking to be the driest of the three days
potentially.

Bottom line, mild with chances for rain. We look to continue to
erode remaining snowpack and river ice during this time.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 658 PM EST Sun Jan 15 2017

VFR conditions expected this evening then clouds and mixed
precipitation arrives during the morning with IFR becoming
widespread by 18z and then LIFR later in the afternoon. The
precipitation should change to rain by afternoon with the chance
of a period of freezing rain between about 15Z and 18Z.

&&

.MARINE...
Issued at 326 PM EST Sun Jan 15 2017

A weak pressure gradient will result in relatively light winds
and low waves over the lake for the next couple of days.


&&

.HYDROLOGY...
Issued at 122 PM EST Sat Jan 14 2017

Rivers are running above normal across the area due to rain, melted
snow and ice jams. The Grand River at Robinson Township has an
active warning for minor flooding. Multiple sites also have active
advisories. A period of colder than normal temperatures through the
weekend may allow river ice to thicken. Next week looks warmer than
normal with highs possibly reaching the 50s. This could melt the
river ice and allow the rivers to flush out.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...Meade
AVIATION...Ostuno
HYDROLOGY...63
MARINE...04



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