Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kgrr 181904 

Area forecast discussion
National Weather Service Grand Rapids Michigan
304 PM EDT sun Aug 18 2019

Latest update...

issued at 304 PM EDT sun Aug 18 2019

- a few more storms are possible this afternoon and again late

- Cooler Wednesday night through Saturday.


Discussion...(this evening through next sunday)
issued at 304 PM EDT sun Aug 18 2019

Surface analysis shows a cold front just crossing Lake Michigan.
Some clearing skies behind the earlier convection are allowing the
atmosphere to recover somewhat, but we're still a couple hours away
from any redevelopment...if it comes at all. However, convective
redevelpment remains a possibility from 4p-8p ahead of the cold
front. Convective inhibition progs suggest that sbsin will fall to
0j/kg by 21z across the cwa.

After the front passes through, mainly dry weather is expected until
late Tuesday ahead of another cold front. We'll maintain pops in the
grids for storm possibilities the air behind the Tuesday front will
be very comfortable as dewpoints fall into the lower 50s. Highs in
the 70s and lows in the mid 50s are expected toward the end of the
week before warmer weather returns for the weekend.


Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 150 PM EDT sun Aug 18 2019

Area of rain continues to press off to the east across southwest
lower Michigan at 18z. This rain is associated with what is left
over from an area of showers/storms that initially moved into
southwest lower Michigan this morning. We are expecting the rain
to continue to diminish/push east over the next hour or two.

The next question is whether or not we see another round of
showers and storms on the cold front that presses in from the west
this evening. The instability has diminished considerably due to
the rain and clouds. We are not expecting a big redevelopment of
the instability, which should keep the shower and storm chances on
the low side. Models continue to hint at showers and storms this
evening towards kbtl and kjxn, but they may not be taking into
account the full extent of how the atmosphere has been stabilized
today. So, for that reasoning have only included vcsh wording in
the tafs for now for this evening.

Next order of business is the threat of low clouds and fog
tonight. Feel the chance for low clouds is high, with all sites
likely seeing MVFR ceilings developing. Cannot rule out some IFR
ceilings along I-94 as well. The front stalls over the area
tonight and the low clouds will likely do the same into the day on
Monday. Some fog is expected tonight as well, but at this point
not expecting it to become dense.


issued at 304 PM EDT sun Aug 18 2019

Frequent wind gusts to 25 knots through late afternoon will be
hazardous to small craft and waves hazardous to beach goers. Small
craft and beach hazards advisories will remain in effect through 8


GRR watches/warnings/advisories...
Michigan...Beach hazards statement until 8 PM EDT this evening for miz037-

Lm...Small Craft Advisory until 8 PM EDT this evening for lmz846>849.



National Weather Service Glossary of Abbreviations