Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 231709
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1209 PM EST Mon Jan 23 2017

LATEST UPDATE...
Hydro

.SYNOPSIS...
Issued at 330 AM EST Mon Jan 23 2017

A trough of low pressure will bring rain showers to the area today
into tonight. The showers will be most numerous this afternoon and
evening. A brief respite from the rain will occur on Tuesday as high
pressure works through the region. Rain will spread back in from the
west Tuesday evening and continue into Wednesday. There is a small
chance that the rain may mix with some snow across Central Lower
Michigan, but the trend has been warmer and more towards all rain. A
slow cooling trend is expected this week, with highs in the lower
40s today cooling to the lower 30s by Friday. Snow returns to the
forecast late in the work week.

&&

.UPDATE...
Issued at 1121 AM EST Mon Jan 23 2017

Rain will continue to be thrown back to the west through the day.
I delayed the higher POPs until toward 00Z when the rain should
be peaking across the CWA. Still questionable if the lakeshore
counties will see much rain, but the rest of the area will. Some
areas toward U.S. 127 should see around a quarter inch of rain,
with trace amounts toward the lakeshore.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 330 AM EST Mon Jan 23 2017

Widespread dense fog has not developed as expected and will be
dropping the advisory for our area. There may yet be some areas of
dense fog this morning, but nothing to the level of an advisory it
appears. At 330am, Ludington in the only observation site in the
entire forecast area at 1/4 visibility.

Rain showers are still expected from today into tonight along an
inverted trough of low pressure. The trough extends from a low
heading off the eastern seaboard today all the way back into Lower
Michigan. We are not expected significant rain and it appears the
trend may be less in areal coverage. We dry out on Tuesday with
ridging working through.

The next system takes aim on Lower Michigan for Tuesday night into
Wednesday. The trend has been toward a warmer, further north system.
With that we have all rain in the forecast now for both Tuesday
night and Wednesday. Depending on the track of the low however we
may need to make changes however. The GFS has a further north track
with the ECMWF being further south. If the further south track
verifies we may need to add snow back in across Central Lower. This
system should bring a more widespread rain to the forecast area.

.LONG TERM...(Wednesday night through Sunday)
Issued at 330 AM EST Mon Jan 23 2017

We`ll be heading back to winter with colder temperatures and lake
effect during the long term.

As low pressure moves away from Michigan Wednesday night, cooler air
will begin to flow south from Canada. Any lingering showers will
become mixed with and eventually change over to snow by Thursday
morning. H8 temps fall to -10c by Thursday night and settle around -
12c to -14c for the rest of the period. Several short wave troughs
dropping south will increase inversion heights during the period and
shsn should have no trouble developing. Several inches of
accumulation seems likely from Friday through Sunday over the
traditional snow belts. We boosted pops over guidance during this
period to reflect higher confidence of shsn.

Temps will fall to near normal levels by the end of the week. We`ll
see highs from the mid to upper 30s Thursday fall to the upper 20s
by Sunday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 658 AM EST Mon Jan 23 2017

Poor aviation conditions are expected the next 24 hours.
Widespread LIFR is in place across the area at 12Z, and this will
likely remain the case going forward for both today and tonight.
Ceilings are expected to remain below 1000ft through Tuesday at
12z and will likely remain below 500ft. Visibilities will likely
stay between 1 and 3 miles the next 24 hours, with the lowest
visibilities below 1 mile occurring this morning and again
potentially overnight. Fog will be prevalent the entire time with
chances for rain showers especially this afternoon and evening.


&&

.MARINE...
Issued at 330 AM EST Mon Jan 23 2017

Winds and waves will remain below advisory criteria through Tuesday.
Tuesday night southerly winds will be on the increase and we could
see Small Craft conditions across the south with a low tracking
across Central Lake Michigan. The track of the low is still a bit
uncertain however so the SCA conditions are as well.


&&

.HYDROLOGY...
Issued at 1209 PM EST Mon Jan 23 2017

River levels are in the process of generally falling with the
recent lack of appreciable rainfall over the past few days and
with the ice having moved out with the warm temperatures.

River levels will likely stabilize or even rise a little with
more precipitation expected through Wednesday. No significant
rises are expected, and no major flooding is expected. We are
looking for up to around or just over half an inch with rain
tonight, and rain/snow Tue night/Wed. The precipitation could fall
as mostly snow up north, limiting immediate runoff into the
rivers.

Conditions will become colder at the end of the week and beyond.
Lake effect snow showers will become likely, with little to no runoff
expected after Thursday.

&&

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

$$

UPDATE...JK
SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...04
AVIATION...Duke
HYDROLOGY...NJJ
MARINE...Duke


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