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000
FXUS63 KGRR 270346
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1146 PM EDT Mon Jun 26 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 322 PM EDT Mon Jun 26 2017

Another afternoon and evening of spotty showers and isolated storms
can be expected tonight as cool Canadian air continues to filter
across the area. Conditions will dry out overnight as the system
begins to pull out. A stray shower will be possible across eastern
areas Tuesday afternoon, but temperatures will warm a few degrees
compared to today.

An occasionally active weather pattern is looking more likely
beginning late Wednesday, and lasting at times through early next
week. Multiple waves of low pressure will move east through the
region at times. These waves will bring the threat of showers and
storms with dry periods in between.

&&

.UPDATE...
Issued at 1103 PM EDT Mon Jun 26 2017

I adjusted the probability of precipitation for the evening to
show the showers will be mostly north of Big Rapids. The showers
will weaken as they move east of Big Rapids.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 322 PM EDT Mon Jun 26 2017

One more round of spotty showers is now beginning to rotate into the
CWFA this afternoon from the NW as one more major wave moves through
the region. The shower chances will linger into the early overnight
period before the wave rotates out. A rumble of thunder will remain
possible as the cold pool aloft interacts with the diurnal heating
this afternoon.

Tuesday should end up mainly dry across the area, however a slight
chance of a rain shower was inserted into the forecast for the
eastern counties. The models have trended toward the cyclonic flow
aloft lingering a little longer. The eastern counties will be on the
wrn periphery of the upper low Tuesday afternoon. Temperatures will
be a few degrees warmer than yesterday with the core of the coolest
air moving east of the area.

We will see a break in the weather then from Tuesday evening through
Wednesday morning. Rain chances will then increase Wednesday
afternoon and especially Wednesday evening. There is a short wave
that is currently coming onshore off of the Pacific to the CA/OR
coast. This short wave will move along the nearly zonal flow that
will take place once the current low moves out. A 60 knot low level
jet is expected to bring a very moist surge to the area. This will
help develop showers/storms over the area Wed afternoon/evening.
Right now, the heavier pcpn looks to occur across the northern
portion of the area given the forecast track of the wave.

Heavy rain is a concern given the heavy rain that has fallen across
portions of Central Michigan over the last week. There is a lot of
wind energy available also that could produce damaging winds. We
will continue to monitor the situation.

.LONG TERM...(Thursday through Monday)
Issued at 322 PM EDT Mon Jun 26 2017

A Low pressure system is expected to pass over Upper Michigan/Lake
Superior Thursday and drape a front across the region, bringing
showers and thunderstorms to Lower Michigan Thursday into Friday.
Instability, moisture, and lift may all be present in sufficient
quantities to make severe weather possible.

Another low pressure system will then move from southwest to
northeast across Lower Michigan Friday and Friday night, accompanied
by more rain and thunderstorms. If the focus of the heavy rain ends
up stretching across the area, we could see areal and river flooding
by the end of the week.

Temperatures will be around normal through the week. Normal highs
are around 80 degrees and normal lows are in the upper 50s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1143 PM EDT Mon Jun 26 2017

Vfr conditions will continue at all the terminals through Tuesday
evening. Sct-bkn fair wx cu will develop Tuesday and isolated
light rain showers may affect our eastern terminals (KLAN and
KJXN) Tuesday afternoon. West winds will increase to around 10-15
kts Tuesday but winds will not be as strong as they have been the
past several days. Skies will clear at all the terminals Tuesday
evening.

&&

.MARINE...
Issued at 1103 PM EDT Mon Jun 26 2017

I expunged the probability for waterspouts due to ending showers.
The marine headlines have been extended into the morning hours
due to persisting higher winds and waves in the southern near
shore zones.


&&

.HYDROLOGY...
Issued at 1119 AM EDT Mon Jun 26 2017

River levels are trying to return to normal across the region...with
the Chippewa River at Mt. Pleasant and Pine River at Alma above flood
stage. Scattered showers and thunderstorms...which will develop as
an upper low moves over the state this afternoon...are not expected
to produce the areal coverage or intensity of precipitation needed
to slow the falling of the stages. Therefore...expect river levels
to continue to fall steadily over the next 24 hours.

Another round of potentially heavy rainfall will occur later
Wednesday into Wednesday night. Deep moisture returns to the
region...and bands of heavy rainfall may occur across central
portions of Lower Michigan. Rivers in Isabella and Gratiot
counties are especially vulnerable to excessive rainfall...and
significant rises would likely develop on the Pine and Chippewa
rivers should the heavy rainfall occur in these basins.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 5 AM EDT Tuesday for MIZ037-043-
     050-056-064-071.

LM...Small Craft Advisory until 5 AM EDT Tuesday for LMZ844>849.

&&

$$

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