Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kgrr 231605 
afdgrr

Area forecast discussion
National Weather Service Grand Rapids Michigan
1205 PM EDT Wed Oct 23 2019

Latest update...
aviation

Synopsis...
issued at 300 am EDT Wed Oct 23 2019

- partly sunny and breezy today

- rain showers late this afternoon and tonight

- fair weather Thursday through midday Saturday

&&

Update...
issued at 1110 am EDT Wed Oct 23 2019

With the winds slowly decreasing along the Lakeshore and values
largely under gale criteria we transitioned the marine headline to
a Small Craft Advisory. We also allowed the Lakeshore Flood
Warning to expire with the waves and water levels decreasing as
well. We are likely going to need higher pops for the rain event
tonight as the incoming data is supporting this possibility.

&&

Discussion...(today through next tuesday)
issued at 300 am EDT Wed Oct 23 2019

Fair wx will briefly return for most of the day today but it will
remain breezy with southwest winds of 15 to 25 mph with some
higher gusts particularly near the Lake Michigan shoreline. A sfc trof
and upper level system will combine to bring some rain showers
late this afternoon and tonight.

The wx pattern will finally become more tranquil as a broad sfc
ridge takes hold of our wx pattern Thursday through Friday into
Saturday. This will result in partly cloudy skies and seasonable
temps for this time of year.

Clouds will be on the increase Saturday out ahead of a southern
stream system that will move NE from the southern Continental U.S.. this
system will bring some showers into our fcst area late Saturday
into Sunday. An overall medium range guidance consensus suggests
that the most significant rainfall will stay se of our fcst area.
Nevertheless some steadier rain showers could arrive by Saturday
night.

Longer range computer model guidance shows potential for a cold
and very unsettled wx pattern to develop toward the very end of
the month as a high amplitude upper trough will amplify over the
Great Lakes region. In fact 00z GFS ensembles indicate the high
temp at kgrr may struggle to reach the 40 degree mark by the
30th/31st and the deterministic Max/min numbers are not
surprisingly even colder then the ensemble mean temps.

&&

Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1205 PM EDT Wed Oct 23 2019

Gusty southwesterly winds will gradually abate this afternoon.
A low pressure system will track roughly along a line from mkg to
GRR to lan after dark with a band of rain and associated MVFR
cigs/visbys. Confidence is high that the band will impact mkg but
low at GRR and lan, so cigs/visbys may end up lower at the latter
two site than currently advertised. At azo/btl/jxn, rain is less
likely but southwesterly wind shear of 40 to 50 kts (highest at
jxn) is expected mainly between 01 and 07z. All precipitation will
end by sunrise with winds becoming northwesterly everywhere.
Broken MVFR clouds will continue toward the end of the taf period.

&&

Marine...
issued at 300 am EDT Wed Oct 23 2019

Gale force winds will continue overnight and the Lake Shore Flood
Warning and Gale Warning headlines have been extended through 11
am. Wave heights will remain significant today only subsiding to
around 3 to 6 feet by mid to late afternoon before finally
subsiding more considerably tonight and Thursday.



&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...Small Craft Advisory until 8 PM EDT this evening for lmz844>849.

&&

$$

Update...mjs

National Weather Service Glossary of Abbreviations