436
FXUS63 KGRR 130016
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
816 PM EDT Sun Jul 12 2026
.KEY MESSAGES...
- Hot and Humid Through First half of the week
- Rain Chances End of the Week
&&
.DISCUSSION...
Issued at 146 PM EDT Sun Jul 12 2026
- Hot and Humid Through First half of the week
As discussed previously, High pressure will track through the upper Midwest
through the first half of the week. The warm air advection
increases tomorrow with +22C at 850mb tomorrow afternoon/evening.
That warm air advection will intensify to it`s highest on Tuesday
upwards of +25C. Unlike the last heat wave, there is less
moisture associated with this one. However, Dewpoints by Tuesday
will be in the upper 60s to low 70s. That will bring RH`s to 80 to
90 Percent, especially along and south of the I 96 corridor. So
while the region will be dry as far as precipitation, it will be
fairly humid, especially on Tuesday. Heat Index values remain just
below criteria for tomorrow, however they should build to
advisory criteria Tuesday. Hight`s across the region Tuesday are
expected to be in the mid to upper 90s with readings of 100
likely, especially along the US 127 corridor Lansing Northward. So
please take precautions this week and limit your time outdoors,
make sure you remain hydrated and be mindful when walking your
pets.
- Rain Chances End of the Week
The high pressure that will bring the heat through the first
half of the week will be dominated by a large upper level low that
will situate itself over NE Canada. There remains some questions
on the timing and strength, but overall that low will drive the
high pressure back into the plains and create a decent pressure
gradient through the Great Lakes region. This will bring NW flow
to the area. So gusty NW flow is possible Thursday into next
weekend. Currently, the mid and low levels could be to dry for
precip on Thursday, though afternoon convection is possible. The
better chances for showers and storms is now Friday
afternoon/evening. Of course depending on timing and strength of
the low and the moistening of the lower levels of Southern
Michigan, this timing is subject to change.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 816 PM EDT Sun Jul 12 2026
VFR conditions are expected the next 24 hours. No restrictions to
visibility are expected and ceilings will remain above 10,000
feet. For the most part we should see mainly clear skies, but
there will be some convective debris clouds at or above 10,000
feet that move through this evening/tonight. Winds will be light
and variable tonight becoming west around 10 knots on Monday after
14z-15z.
&&
.MARINE...
Issued at 150 PM EDT Sun Jul 12 2026
Overall fairly weak flow as high pressure dominates the area
through the first half of the week. Waves will be less than 3 foot
through most of the period. Northwest flow will intensify through
the latter portion of Wednesday. That could allow waves to get to
3 to 4 feet but remain below Small Craft advisory and Beach
Hazard criteria.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Ceru
AVIATION...Duke
MARINE...Ceru
NWS GRR Office Area Forecast Discussion
