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Area forecast discussion 
National Weather Service Grand Rapids Michigan
1211 am EDT Friday Jul 31 2015

Latest update...
aviation

Synopsis...
issued at 329 PM EDT Thursday Jul 30 2015

The next couple of days will be dry and mild. The next chance of
rain is Saturday night and Sunday when low pressure moves across
lower Michigan. Highs will be seasonal with lower to middle 80s
expected.

&&

Short term...(this evening through Saturday night)
issued at 329 PM EDT Thursday Jul 30 2015

Forecast concerns deal with precipitation chances Saturday night.

Northwest flow aloft will produce comfortable weather through
Saturday with dewpoints in the 50s and highs in the lower to middle
80s. The main weather maker in the long term is a compact short wave
that moves from Manitoba southeast across The Straits. The surface low
associated with it is a bit displaced, located over South Dakota
early Saturday. This low is forecasted to move across southern WI/northern Illinois and
southern lower Saturday night. We included chance probability of precipitation for this low but there
is some model discrepancy. The European model (ecmwf) is much weaker and farther
south with this low and doesn/T produce precipitation over the County Warning Area at all.
Instability is not great either. Overall...this looks like a pretty
tame system with not much expected of it.

Long term...(sunday through thursday)
issued at 329 PM EDT Thursday Jul 30 2015

Main story in the long term continues to be the evolution of an
upper low centered over Ontario/Quebec much of the period. The upper
low gradually meanders from Ontario into Quebec through the long
term...with the main long wave trough pivoting through the Great
Lakes region Monday/Tuesday. Tuesday through Thursday looks to be
the coolest days with 850mb temperatures dropping into the +5 to +10c
range. The GFS is the cooler of the two models.

Given upper troughing and shortwaves swinging around the main upper
low have chances of showers and/or storms through much of the long
term. Not expecting an extensive rain but there will be showery
periods. Have highs around 80 on Sunday/Monday tapering back to the
70s Tuesday through Thursday.

&&

Aviation...(for the 06z tafs through 06z Friday night)
issued at 1207 am EDT Friday Jul 31 2015

VFR conditions will continue at all the terminals through the next
24 hours. West winds will increase to 15 kts with frequent gusts
to 20 to 25 kts from late Friday morning through Friday afternoon.
Winds will diminish Friday evening.

&&

Marine...
issued at 329 PM EDT Thursday Jul 30 2015

Wind and waves will continue to decrease this evening and remain
light through Friday.



&&

Hydrology...
issued at 1232 PM EDT Thursday Jul 30 2015

River levels continue to fall and are expected to continue to fall
for at least the next week as rainfall amounts are not expected to
be enough to cause the rivers to start rising.

&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...none.
&&

$$

Synopsis...04
short term...04
long term...Duke
aviation...Laurens
hydrology...wdm
marine...04

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