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000 
FXUS63 KGRR 210005
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
805 PM EDT Wed Sep 20 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Wed Sep 20 2017

Unseasonably hot and dry weather is expected through the weekend.
There is a weak cold front coming into the area tonight that may
bring some thunderstorms to areas west of Holland to Big Rapids 
early Thursday morning. Highs will likely be around 90 to the mid 
90s Thursday and Friday, then in the mid to upper 80s over the 
weekend. 

&&

.SHORT TERM...(This evening through Friday night)
Issued at 330 PM EDT Wed Sep 20 2017

We do have a cold front with convection associated with it 
heading into our CWA overnight. The front will dissipate by midday
Thursday. Even so, we have good moisture transport and 
convergence north of MKG after midnight. There is instability and
the nose of the low level jet pokes into the area too so I do 
expect thunderstorms between midnight and sunrise over our NW CWA.
Those will dissipate by mid morning and likely will not impact 
areas east of US-131. 

High pressure rules after that. The 1000/850 thickness and 850
temps suggest highs in the lower to mid 90s Thu and Fri.

.LONG TERM...(Saturday through Wednesday)
Issued at 330 PM EDT Wed Sep 20 2017

Strong upper ridge with 590+ dm heights will be centered over the
Central Great Lakes through the weekend. Deep layer subsidence 
will provide dry weather and mostly clear/sunny skies, and support
a continuation of very warm temperatures. High temperatures on 
Saturday look to again approach records, with the expectation of 
high reaching the mid 80s to low 90s.

Energy ejecting out of the west coast trough will work through the 
Great Lakes midweek, pushing a cold front through Lower Michigan 
Tuesday night and Wednesday. This will provide a chance for showers 
and thunderstorms, and usher in cooler and more seasonable 
temperatures on Wednesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 805 PM EDT Wed Sep 20 2017

Other than a period of MVFR fog (vsbys 3-5SM) from roughly 09z-
14z, predominately VFR weather is expected the next 24 hours. 

The line of tstms currently over WI is expected to weaken as it 
crosses lake MI later this evening, but could still impact MKG 
before dissipating. A brief period of gusty/erratic winds may 
occur overnight as whatever is left of that line moves through 
MKG.

Isolated storms may develop Thursday afternoon, especially east 
of GRR, but did not include thunder in any of the TAFs due to 
very low probability/limited coverage. 

&&

.MARINE...
Issued at 330 PM EDT Wed Sep 20 2017

There will be some thunderstorms overnight as the frontal band
moves through so higher winds and waves should be expected near
those storms. After that, from mid day Thursday into the weekend
high pressure means light winds. Dew points should not get high
enough to result in dense fog but that is something to think
about even so.


&&

.HYDROLOGY...
Issued at 330 PM EDT Wed Sep 20 2017

Abnormally dry conditions are expected to continue into next week 
aside from isolated pockets of heavy downpours. The most favored 
locations for isolated showers and storms Wed night will be near 
Lake Michigan, then on Thu in Central Michigan. Thereafter, warm and 
dry weather is expected to dominate into early next week.

&&

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

$$

SYNOPSIS...WDM

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