121
FXUS63 KGRR 021053
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
653 AM EDT Thu Jul 2 2026
.KEY MESSAGES...
- Convective trends remain the main forecast concern
- Heat continues into the holiday weekend
&&
.DISCUSSION...
Issued at 412 AM EDT Thu Jul 2 2026
- Convective trends remain the main forecast concern
A quasi-stationary front drove convection upstream yesterday
evening and into the overnight hours. This activity moved into
far northern sections of the forecast area yesterday evening and
into tonight. For our area we remain on the warm side of the
boundary with around 2,000 j/kg of MUCAPE at 400am. Confidence in
storm morphology remains on the lower side overall. A strong low
level jet is in place overhead this morning which is usually a
driver of additional storms. The SPC HREF does indicate a round of
convection during the morning and into the midday hours between
roughly 10am and 2pm. We are in a marginal to slight risk for
severe weather today via the SPC and this is largely tied to the
level of instability that will be in place. Some stronger winds in
the profile will make damaging winds the main threat. Another
round of storms is expected this evening. Heavy rain is also very
possible today with high PWAT air in place and a boundary to focus
the storms.
We remain in a threat for severe weather both Friday and Saturday with
the SPC having us in a marginal threat both days. Convection will
be driven by a stationary front remaining in the area and mid
level MCV`s floating through the region to enhance the threat.
Again, confidence is on the lower side with regard to how storms
evolve each day. Heavy rain will remain a threat on Friday and
Saturday as the airmass will largely remain the same.
- Heat continues into the holiday weekend
GFS MOS numbers look more reasonable which keeps temperatures in
the 90s today, Friday and Saturday (or at least near 90). We
"cool" back into the 80s for highs on Sunday and into early next
week. Will maintain the current Heat Warning as is, but we may
need to extend it into Friday at least.
&&
.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 653 AM EDT Thu Jul 2 2026
The main concern remains the threat of thunderstorms today.
Confidence in how storms evolve today remains low, but we feel
there are two main time frames that could affect aviation
interests in this TAF period. The first is from mid morning into
early afternoon, roughly 14z through 19z. This threat is most
likely tied to the ongoing batch of showers/storms over Lake
Michigan. This activity looks to remain on the smaller side in
terms of aerial coverage, but I-96 TAF sites look to be the
favored location. A second round of storms looks to press in from
the west after 00z. These storms will be more widespread and may
have a risk of stronger thunderstorms winds in excess of 40 knots.
Do not have that level of wind in the TAFs at this point given low
confidence.
Otherwise, look for southwest winds to become gusty this afternoon
at 10-20 knots with some gusts to around 25 knots.
&&
.MARINE...
Issued at 412 AM EDT Thu Jul 2 2026
We were previously thinking that winds and waves would be near
advisory criteria levels at this time, but that has not panned
out early this morning. Winds are well below criteria at this
point with many sites falling below 10 knots. Buoys at present are
indicating 1 foot waves. So, no need to issue any headlines this
morning given current conditions and what the rest of today and
tonight look like. We may see conditions come up to a moderate
swim risk today, otherwise we are heading into a lighter wind
regime as we move into and through the holiday weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Extreme Heat Warning until 8 PM EDT this evening for MIZ037>040-
043>046-050>052-056>059-064>067-071>074.
MARINE...None.
&&
$$
DISCUSSION...Duke
AVIATION...Duke
MARINE...Duke
NWS GRR Office Area Forecast Discussion
