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000
FXUS63 KGRR 240422
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1222 AM EDT Sun Sep 24 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 300 PM EDT Sat Sep 23 2017

Hot and humid weather will continue through the weekend into early
next week. A cold front will bring a chance of showers Wednesday
and a stronger cold front will bring showers and thunderstorms
with much cooler air late in the week.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 300 PM EDT Sat Sep 23 2017

Sfc/upper ridging and persistent south to sw flow waa will result
in a continuation of unseasonably hot and humid wx through the
short term fcst period. High temps Sunday will again reach the
upper 80`s to lower 90`s with a couple of mid 90`s maxes possible
once again at typically hottest/driest locations from KGRR/KLAN
off to the south. Heat indices Sunday afternoon will once again
reach well into the 90`s.

Large scale subsidence and lack of a forcing mechanism for
convective initiation to occur should result in persistent dry
conditions through the short term fcst period. A cu field has
developed mainly north of I-96 and near to east of US-131 and it
is not completely impossible that an isolated shower may develop
near KMOP late this aftn when instability will be maximized.
Therefore I added mention of isolated showers to the fcst late
aftn/early eve over our far ne fcst area.

.LONG TERM...(Tuesday through Saturday)
Issued at 300 PM EDT Sat Sep 23 2017

Confidence remains high that a sharp cool down will take place at
the end of next week. However prospects are not looking good for any
widespread appreciable rainfall. Looks like the drought continues.

Guidance is similar in showing the first cold frontal passage on
Tuesday night/early Wednesday although this feature comes through
mostly dry due to limited moisture/upper support and unfavorable
timing of the frontal passage. Actually Wednesday and Thursday
should be pleasant days with lower dew points behind the sfc front
but temps still a bit above normal.

Perhaps a better risk of rain showers arrives for late Thursday
night into Friday with the main push of cold air and arrival of the
upper trough. However there is not much support for lake
effect/enhancement since the low level flow goes northerly once the
coldest air comes in and sfc ridging is already building in on
Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1222 AM EDT Sun Sep 24 2017

Dewpoints have trended down over the past 24 hours, so the
potential for late night/early morning fog seems less now. Left a
bit of fog in the JXN TAF, otherwise vsbys should largely stay
unrestricted. VFR conditions will prevail through the next 24
hours with a light SSE wind at 8 knots or less.

&&

.MARINE...
Issued at 300 PM EDT Sat Sep 23 2017

Wave heights will remain minimal at less than 2 feet through the
rest of the weekend with south to southwest winds around 5 to 10
kts.


&&

.HYDROLOGY...
Issued at 1131 AM EDT Sat Sep 23 2017

Rivers are running around normal to below normal for the time of
year. Meanwhile, the US Drought Monitor is indicating dry conditions
across Southern Lower Michigan. Near-record warmth is expected today
through Monday. The next good chance for rain is Wednesday. No river
issues are expected through the week.

&&

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

$$

SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...Meade
AVIATION...JK
HYDROLOGY...63
MARINE...Laurens