Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 211748
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1248 PM EST Sat Jan 21 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 AM EST Sat Jan 21 2017

Today will start out with dense fog and scattered rain shower but
the passage of a warm front late this morning should push the
showers and fog north of the area. It will also push our air
temperatures into the mid 50s near and south of I-96. However a
storm developing over Colorado this morning will track into the
Southern Plains Sunday and a trailing cold front from the northern
system will push through the area ending our brief warm spell.
Scattered showers are possible.

Sunday night into Monday there is some question as to how far
north that system gets but the current thinking it will get close
enough to bring us rain Sunday night into Monday. The next storm
coming trough, in the Wednesday time frame will bring winter back
to the area. This should be a rain to snow event and after that it
should be below freezing with periods of snow into the following
week.

&&

.UPDATE...
Issued at 654 AM EST Sat Jan 21 2017

The dense fog is gone, no observations at 6 am had visibilities
under a 1/2 mile and most locations were over 2 miles. I see no
reason to believe the fog will redevelop this morning (it may
tonight) so I have expunged it.

UPDATE Issued at 416 AM EST Sat Jan 21 2017

I have canceled the fog advisory along and south of I-96.
The fog has been mixed out due to the showers assoicated with the
warm front moving through the area. Since visibilities remain
greater than 3 miles at all reporting stations south of I-96 and
across all of Indiana and Illinois at 4 am it makes sense the fog
would not come back in. The fog lifting northward has been shown
nicely by the RAP model run after run since midnight, so I feel
really safe canceling it near and south of I-96. We may be able to
expunge the rest of it shortly after sunrise.

&&

.SHORT TERM...(Today through Monday)
Issued at 330 AM EST Sat Jan 21 2017

There are several issue to deal with this morning. The first is
the fog advisory and what to do with it. Next is the showers
around us...and what to do with that. The other issue is that
storm that for Monday, how close does it get to us?

First for the fog, after coordinating with IWX, I plan on killing
the advisory south of I-96 but holding on to it north of that. We
have a warm front, which at 3 am was just south of I-96 as winds
are from the south near I-94 with temps in the mid 40s, while over
I-96 area winds are east and temperatures are in the 30s. There
is an area of showers are just north of the warm front but it is
moving northward. South of the warm front visibilities are over 5
miles. So it will lift north and kill the fog.

With the warm front lifting north of the area by late morning we
will be in the warm wedge until the cold front comes through
Sunday morning. This may lead to a few hours of sunshine this
afternoon. However since temperatures are currently near 50
degrees south of I-80 at this hour it seems more than reasonable
to believe we will see highs in the mid to upper 50s near and
south of i-96 this afternoon.

The cold front trailing the weakening system lifting northeast
across Wisconsin today will cross our area early Sunday morning.
There may just be enough lift and moisture to get a few showers
from that front but any precipitation would be light and not cause
any significant issues with flooding.

The system for Monday has been tracking more and more to the
Northwest with each model run on the ECMWF, GFS and NAM for
several days in a row now. I am thinking we will get rain from
this system. Even through we are on the northwest side of the
system and it is still January, there just is not enough cold air
in place over the western Great Lakes to give us snow from this
system. If it tracks any more to the northwest we may get enough
rain to cause additional flooding issues.

.LONG TERM...(Monday night through Friday)
Issued at 330 AM EST Sat Jan 21 2017

A sfc/upper trough will bring extensive cloud cover and showers
Monday night before showers taper off Tuesday as upper ridging very
briefly builds in. Unseasonably mild wx will continue Monday
night through midweek.

A fairly strong low pressure system will move northeast into the
Great Lakes region Tuesday night and Wednesday and bring potential
for mixed pcpn. A consensus of latest medium range guidance
continues to suggest a mix of pcpn at the onset of pcpn Tuesday
night followed by mainly rain for most of our fcst area Wednesday
with a rain/snow mix over our northern fcst area.

This system will need to be monitored closely as a low track a
little further south and earlier arrival of colder air would
potentially bring accumulating snow to a larger portion of our area.
Temperatures will finally cool to closer to normal for this time of
year behind that system for late in the week in a nw flow caa
pattern.

Scattered snow showers are also anticipated late in the week as an
upper trough settles over the Great Lakes region. H8 temps will also
likely be cold enough for some lake effect snow showers late in the
week as well.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1247 PM EST Sat Jan 21 2017

Conditions are improving this afternoon as low clouds and fogs mix
out with IFR and LIFR improving to VFR from north to south.
Conditions will go back down to IFR and LIFR later tonight and
into Sunday morning.

&&

.MARINE...
Issued at 416 AM EST Sat Jan 21 2017

I canceled the fog advisory over our near shore waters. Due to
the southerly winds assoicated with the warm front, nearly all
reporting stations near the Lake Michigan shore from Benton Harbor
to Traverse City have visibility`s of 5 miles or higher. The RAP
model shows the fog continuing over the off shore water most of
the day but not over the near shore.


&&

.HYDROLOGY...
Issued at 326 PM EST Fri Jan 20 2017

The Grand River at Robinson Township has been falling to near flood
stage today. Runoff from rain earlier this week is being routed
downriver as the ice restrictions decrease. Most rivers are rising
due to the rain, but seem to have less notable ice impacts now.
Temperatures (and dew points) will be above 32 degrees through the
middle of next week, with highs at or above 50 possible Saturday and
Sunday. The remaining river ice should move out or melt, at which
time flooding at Robinson would likely alleviate. Low-land flooding
near riverbanks is occurring at multiple forecast points, but
impacts to property are minor.

&&

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

$$

UPDATE...WDM
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...Laurens
AVIATION...Ostuno
HYDROLOGY...63
MARINE...WDM


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