Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 152339
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
639 PM EST Wed Feb 15 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 256 PM EST Wed Feb 15 2017

a ridge of high pressure will move over the state tonight. We`ll see
snow showers begin to diminish as drier and warmer air aloft arrive.
The next few days will be dry and warmer as temperatures climb into
the 50s by Saturday.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 256 PM EST Wed Feb 15 2017

Forecast concerns are minimal this afternoon and mainly deal with
the end of the current snow shower activity.

Latest sfc analysis shows a high pressure ridge extending from the
MN arrowhead south across western IA. This ridge will move over the
Lower Michigan tonight and push the deep upper currently in place to
the east. Warmer air on the back side of the ridge will begin moving
across the lake tonight and we`ll see snow showers diminish as a
result. We should be looking at generally dry conditons Thursday; a
few lingering flurries along the lake shore remain possible.
Thursday will still be chilly with highs in the lower 30s. However,
a warm front will lift north early Friday and temps will climb into
the 40s with 50s expected Saturday. Subsidence from the upper ridge
will result in some sunshine over the weekend.

.LONG TERM...(Saturday through Wednesday)
Issued at 256 PM EST Wed Feb 15 2017

Only weather maker in the extended is a northern stream low that
swings a weak front through Monday night or Tuesday. Still uncertain
on the timing and my preference is to go with the slower ECMWF given
shortwave ridging ahead of the low may be slower to yield to precip.
The trends are for less precip as this low remains separate from the
southern stream and so there is not as much Gulf moisture drawn
north. P-type looks to be all rain even up north as suggested by
thickness tools and forecast thermal profiles.

Another area of model disagreement occurs Tuesday night and
Wednesday as the GFS brings in a quick return of moisture with sfc
low moving in from the west. In contrast, the ECMWF has sfc ridging
during this period with the low minoring out west of Lower Michigan
on Wednesday as a more consolidated system forms over the Plains.
The blended POPs were lowered here with chance POPS spread out
across Tuesday night and Wednesday. Expect mostly rain with this,
although P-type could be an issue, especially up north, as there are
hints that some cold air is available via sfc ridging extending into
Lower Michigan from an arctic high centered near Hudson Bay.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 634 PM EST Wed Feb 15 2017

MVFR clouds will continue to cover the TAF sites through the
evening. Conditions do remain favorable for snow showers through
about midnight...but the current pattern supports mostly limited
aviation impacts. If a heavier snow shower does develop...IFR
impacts could certainly occur. The clouds will start to break up
overnight...and currently Thursday is looking like a VFR day for
flying as the low level moisture will be on the decrease. Also the
tight pressure gradient that has been in place will be
decreasing. This will result in less in the way of wind for
Thursday as well.

&&

.MARINE...
Issued at 256 PM EST Wed Feb 15 2017

Winds and waves will gradually decrease tonight as high pressure
moves overhead. The small craft advisory remains in effect through
late tonight.


&&

.HYDROLOGY...
Issued at 131 PM EST Wed Feb 15 2017

River levels continue above normal, but no flooding is expected
into next week. Little precipitation is expected, so river levels
should fall into next week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 5 AM EST Thursday for LMZ844>849.

&&

$$

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



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