135
FXUS63 KGRR 172258
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
658 PM EDT Tue Sep 17 2024

.KEY MESSAGES...

- Dry and warm weather continues

- Slight chances for rain late this week into next week

&&

.DISCUSSION...
Issued at 328 PM EDT Tue Sep 17 2024

Short term: Persistence forecast the way to go in continued
stagnant pattern with light winds and mainly clear skies. Cool
overnight lows in the upr 40s to mid 50s and patchy ground fog
followed by warm/dry daytime conditions with highs in the lower to
mid 80s. Guidance is showing higher sfc dew pts arriving from the
east on Wednesday which could support a cumulus field, but
suspect daytime mixing will just lower sfc dew pts again in the
afternoon. Fine viewing conditions tonight for the 1044 PM partial
eclipse of the full harvest moon.

Longer term: High pressure will continue to dominate the weather
pattern through the work week. This high will allow for maximum
temperatures to remain in the 80s through the week with a dry
forecast through most of Friday.

There continues to be a signal through the mid range models with
all the deterministic models showing a persistent 500 mb short
wave moving through the upper midwest Friday into Saturday. This
negatively tilted trough should be pulling in mid level moisture
that across the lakes could be enough to bring some moisture into
the western half of lower Michigan. There remains some questions
whether or not there will be enough moisture to overcome the dry
air that has been entrenched over Michigan this past week. The
cold front associated with that trough will lower temperatures
into the 70s into the weekend, the slightly anomalous moisture
might not be enough to create precipitation.

The ridge will continue to be weathered down with a larger,
deeper upper level low will move from the southwest into the
central plains. There remains a bit of discrepancy on the timing
of that low, but as the low from the southwest moves eastward,
another short wave will be moving along the Canadian border and
into the midwest. Convergence between these two system will bring
a better chance of precipitation Sunday into Monday. As stated
previously, there remains some strength and timing but the next
best chance for rain are Sunday into Monday.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 658 PM EDT Tue Sep 17 2024

Mainly clear skies will continue to rule in this forecast period.
We will be watching for some fog potential late tonight. Guidance
continues to indicate some potential. Given the dew points and
crossover temps in the 40s, seems like it will be difficult to do
that without any significant moisture advection. Thinking if we
get fog, it will be shallow ground fog with the warm ground and
cool temps overnight. Decided to handle this with a VCFG.

Whatever fog may occur will burn off/mix out quickly by 14z
Wednesday. That will leave mainly clear skies again with maybe
some cumulus development toward KJXN. KMKG will see a lake breeze
develop toward 18z Wed also.

&&

.MARINE...
Issued at 328 PM EDT Tue Sep 17 2024

Very tranquil conditions for mid Sept continuing on Lk MI with
winds generally only 5-10 kts and waves a foot or less. Expect
onshore lake breezes developing in the afternoon and offshore
breezes occurring at night.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Meade/Ceru
AVIATION...NJJ
MARINE...Meade