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Area forecast discussion 
National Weather Service Grand Rapids Michigan
758 PM EDT sun Oct 4 2015

Latest update...

issued at 316 PM EDT sun Oct 4 2015

Clouds and a few showers will remain over lower Michigan through
Monday morning then fair weather returns for the first half of the
week. Low pressure could bring some rain on Thursday and into


Short term...(this evening through Tuesday night)
issued at 316 PM EDT sun Oct 4 2015

Forecast issue in the near term is for probability of precipitation tonight and Monday as
weak shortwave trough moves through with deep moisture already in
place. Based on model x-sections of Omega...expect there to be some
enhancement of showers across the northern forecast area between
06z and 12z tonight. We will have slight chance probability of precipitation this evening
up there and then chance probability of precipitation after midnight.

Showers should end Monday morning as weak trough is replaced by
Flat Ridge and then fair weather lasts through the end of the
period under zonal flow.

Long term...(wednesday through sunday)
issued at 316 PM EDT sun Oct 4 2015

The main challenge in the long term deals with the potential for
thunder Thursday into Thursday night.

The models are in decent agreement in tracking a middle level
shortwave into the Great Lakes region Thursday night. This system
taps Gulf moisture as it tracks through with precipitable water values up around
1.5 inches. Some instability is showing up...and we will need to
monitor the thunder risk. The soundings around Grand Rapids from
the GFS and high res Euro at 06z Friday show the cape to be thin and
only up to around 500 mb. For now will keep the thunder out of the
forecast. Still with a decent 30 to 40 knot low level
unseasonably moist airmass and lift associated with the wave
passing through...I will feature high probability of precipitation in the forecast later
Thursday through Thursday night.

How quickly the moisture departs on Friday is not clear. The GFS
shows considerable drying in the dgz. The new high res Euro keeps
it moist. Will hold onto mostly chance probability of precipitation Friday to account for
this potential.

Temperatures Wednesday into Thursday will end up warmer than normal.
850 mb temperatures climb above 10 degree c as the Gulf opens up. Some
70s look possible especially toward Kalamazoo.


Aviation...(for the 00z tafs through 00z Monday evening)
issued at 758 PM EDT sun Oct 4 2015

Widespread IFR ceilings are expected again tonight and Monday
morning... with some LIFR or even vlifr conditions likely
developing as well after 06z mainly south and east of GRR.
Ceilings/visibilities gradually improving after 15z Monday to MVFR.


issued at 316 PM EDT sun Oct 4 2015

Winds and waves will be relatively light the next couple of days.


issued at 316 PM EDT sun Oct 4 2015

Most areas except for the northwestern County Warning Area received between a tenth
and third of an inch of needed rainfall this weekend. Most rivers
are at near normal levels for October. Thursday to Friday will be
the next chance of appreciable rainfall.


GRR watches/warnings/advisories...


short term...ostuno
long term...mjs

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