Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 271743
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1243 PM EST Mon Feb 27 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 317 AM EST Mon Feb 27 2017

Low pressure will move across the Great Lakes on Tuesday and
Wednesday. Rain will begin Tuesday and continue into Wednesday
then change over to snow on Wednesday before tapering off to snow
showers on Wednesday evening.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 317 AM EST Mon Feb 27 2017

Arrival of precip Tuesday morning looks to be a little slower than
previous forecast so adjustments were made there. Could be a mix
with snow when it breaks out up north but should change over to
all rain by 12Z Tuesday.

Ensembles and the last several runs of the operational models
suggest strong convection will focus in the warm sector across
Indiana and Ohio on Tuesday afternoon and evening. Shear and
instability from forecast soundings look similar to the event this
past Friday so some strong storms are possible across roughly the
southern half of the forecast area.

The sfc low is progged to move east and deepen on Tuesday night
with colder air moving in on Wednesday behind the low. Rain will
change over to snow from northwest to southeast during the
afternoon with only light accums expected, similar to the past
several storms that have taken similar tracks and evolution over
the past couple months.

.LONG TERM...(Wednesday night through Sunday)
Issued at 317 AM EST Mon Feb 27 2017

Sfc low pressure will be moving away from the cwa Wednesday night.
However, the upper low will continue to move across the Great Lakes
and so we`ll continue with pops but diminish overnight.

Both the ecmwf and gfs and to a lesser degree the nam show a clipper
moving across the southern cwa Thursday. We could see an inch or two
from this system. A shot of arctic air will move in behind the
clipper and we`ll see some lake effect develop. H8 temps fall from
-10c at 00z Friday to -16c by 12z Friday. There will be more than
enough instability over the lake to generate snow showers. However,
moisture is a bit weak so accums will be held down. Snow showers
will continue into Friday evening before diminishing. The boundary
layer does moisten somewhat, though, late Friday night as warm
advection begins. It`s possible we`ll see some light synoptic snow
from that by Saturday morning. Light rain is possible Sunday
afternoon as a warm front lifts north across the cwa.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1244 PM EST Mon Feb 27 2017

While skies are for the most part clear now, a storm system
developing over the "Front Range" will surge moisture northward
into Michigan tonight (from the Gulf of Mexico) and that will
create low clouds and rain after 09z and bring IFR cigs and vis to
the area by 12z. The rain may come to end for a time tomorrow
afternoon but the IFR cigs/vis(fog) will likely continue past 00z
on Wednesday.



&&

.MARINE...
Issued at 317 AM EST Mon Feb 27 2017

Will cancel the Small Craft Advisory with this issuance as winds
and waves are decreasing blo criteria.


&&

.HYDROLOGY...
Issued at 325 PM EST Sun Feb 26 2017

Many rivers have experienced within bank rises after Thursday and
Friday`s rainfall. Some out of bank rises at Croton, Maple Rapids,
and Ionia have occurred. It appears that no further rises will occur
at Croton so the worst may be over. Rain is expected primarily
Tuesday and Wednesday. Some areas may get over a half inch of rain.
While this is not expected to create flooding, there may be
additional within bank rises on rivers or possibly out of bank rises
if more of the rain falls over the Muskegon and Grand River basins.

&&

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

$$

SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...04
AVIATION...WDM
HYDROLOGY...Hoving
MARINE...Ostuno



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