Dimondale, Michigan Weather Forecast Discussion

707
FXUS63 KGRR 171921
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
Issued by National Weather Service Detroit/Pontiac MI
321 PM EDT Wed Sep 17 2025
.KEY MESSAGES...
- Very warm temperatures again on Thursday.
- A little cooler Friday into Saturday. Warmer with increasing rain
chances by the end of the weekend.
&&
.DISCUSSION...
Issued at 318 PM EDT Wed Sep 17 2025
Mid level riding and sfc high pressure overhead will support light
and variable winds and optimal radiational cooling tonight, allowing
nighttime mins to drop down into the 50s. Fog potential tonight will
be through radiational processes and most favorable in low lying
areas. Mid level short wave energy will cause some suppression of
the mid level ridge axis across the northern Great Lakes tonight and
will drive a weak cold front south into central Lower Mi by late
Thursday afternoon. An axis of low level moisture is forecast to
advect into the frontal boundary and result in weak instability as
the front advances into Central Lower Mi. Hi res model guidance
suggests enhanced low level frontal convergence aided by flow off
Saginaw Bay will result in scattered late day convection across the
Tri Cities, Mt Pleasant and Clare. A few solutions actually suggest
some residual convection pushing southward toward Flint and Lansing
by evening with some erosion of the mid level cap. Otherwise
prefrontal warmth and respectable mixing heights will result in
another very warm day with highs possibly well into the 80s.
Mid level ridging is forecast re expand across Lower Mi Thurs night
into Friday. The strength of the northeasterly gradient across Lake
Huron will hold the lower tropospheric front over Lower Mi despite
the increasing mid level height field. This will result in a
respectable thermal gradient across southern Michigan. Locations
around Kalamazoo and Battle Creek are likely to remain in the warm
sector, resulting in highs in the low 80s again while temps from
central Michigan across the thumb region may be stuck in the 60s.
The depth of moisture trapped under a deep frontal inversion will
result in more cloud cover across much of the area. Model soundings
have some indications of a drizzle potential Thurs night into Friday
from Central Michigan/Tri Cities across the thumb.
The blocking pattern which has held strong mid level ridging
overhead for the last week will gradually break down this weekend as
the mid level flow becomes more progressive. The upper low now over
the northern plains will lift across the northern Great Lakes this
weekend, driving mid level high falls across Lower Mi. Southerly
flow will also advect a little deeper moisture into the Great Lakes
toward Sunday, warranting a the next chance for rain. Residual low
level dry air associated with departing high pressure to the east
support a continued dry forecast through at least the afternoon
Saturday.
&&
.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 146 PM EDT Wed Sep 17 2025
Clear skies are observed across much of lower MI this afternoon,
with any diurnal cu field tied closely to marine layer moisture.
High pressure ensures a generally quiet TAF period with light and
variable winds expected for the rest of today and tonight. Several
sites reported BR/FG this morning, with similar conditions
expected again Thursday morning due to favorable radiative cooling
and calm winds. TEMPO groups were included to highlight the
morning fog window. By mid-day Thursday, a cold front reaches the
northern portions of the airspace and organizes light winds out of
the northwest in its wake.
&&
.MARINE...
Issued at 328 AM EDT Wed Sep 17 2025
Winds build tomorrow behind the backdoor cold front with
northerly winds around 10 to 20 knots. Easterly winds then return
until more southwesterly flow develops Sunday and continues into
next week. With this change in the wind there will also be chances
for showers and even a few thunderstorms. At this time Small
Craft Advisory conditions are not expected over the next week.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...SC
AVIATION...MV
MARINE...99

NWS GRR Office Area Forecast Discussion