Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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611
FXUS63 KGRR 132337
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
637 PM EST Fri Jan 13 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EST Fri Jan 13 2017

The January thaw will be in full force next week as temperatures
climb into the 40s and 50s by the end of the week. Prior to that, we
may see a brief period of freezing rain Monday before the
precipitation turns to rain.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 330 PM EST Fri Jan 13 2017

Forecast concerns are minimal through the period and center on low
chances for light snow tonight and the potential for snow or
freezing rain late Sunday night.

Latest regional radar shows light snow falling over the upper
Midwest across Minnesota, Iowa, and Wisconsin. There is a weak wave
moving across the region that will affect the northern cwa tonight.
We included low pops to reflect this possibility, but it`s certainly
possible that many locations won`t see any snow.

Then we have a couple of days of dry weather for the weekend where
we will actually see some sunshine late Saturday and Sunday before
clouds move back in ahead of the storm that will produce quite a bit
of ice across the Missouri and Ohio valleys.

Short range models show light pcpn developing in the warm advection
pattern late Sunday night over far southwest Lower Michigan. Wet
bulb temps would suggest that pcpn at the very onset after 09z
should be snow with freezing rain potentially developing after 12z
Monday.

.LONG TERM...(Monday through Friday)
Issued at 330 PM EST Fri Jan 13 2017

The two main items to focus on in the long term portion of the
forecast are the threat for freezing rain on Monday and a warm up
that will occur next week.

Models are still forecasting a low to move out of the plains states
early next week which will bring a surge of warm air out of the
south. For a time on Monday, cold low level air will remain in place
setting the state for a period of freezing rain. It does not look
like the cold air is all that strong however and it does not appear
to remain entrenched very long. The warm air will win in a
scenario with a low moving northward through the region. The
potential is certainly there for period of freezing rain on
Monday, with Central Lower Michigan standing the best chance for a
longer icing duration. Feel any icing will likely be on the
lighter side, on the order of a tenth of an inch or so or less.
That said however, it does not take much ice to have significant
travel impacts.

The warm air should be firmly in place on Tuesday for just a plain
rain. Precipitation should come to an end Tuesday night as the low
pulls away to the northeast.

Wednesday through Friday looks to be mainly dry with rising heights
and warming temperatures. 850mb temps warm towards +8C on Friday.
Highs on Friday may push into the 50s. A further melt of river ice
and snowpack will occur late next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 637 PM EST Fri Jan 13 2017

Very little to no impact for aviation interests over the next 24
hours and likely beyond. Skies are OVC, but cigs are running from
10-15k ft across the area with very dry air in the lower section
of the atmosphere. We will see cigs potentially lower for a time
tonight through about 06z or so, but only as low as 5k ft. After
that, cigs will lift back up to 15-20k ft and remain there through
the end of the period.

Winds will remain below 10 knots through the period. They are
starting out tonight from the east, and will switch to become from
the west Sat afternoon.

&&

.MARINE...
Issued at 330 PM EST Fri Jan 13 2017

A couple of days of quiet wx is expected with relatively light winds
and wave heights below 3 feet. Winds will pick up again Sunday
night.


&&

.HYDROLOGY...
Issued at 145 PM EST Fri Jan 13 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.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...Duke
AVIATION...NJJ
HYDROLOGY...63
MARINE...04



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