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Area forecast discussion
National Weather Service Grand Rapids Michigan
726 PM EDT Tue Jun 18 2019

Latest update...
aviation

Synopsis...
issued at 323 PM EDT Tue Jun 18 2019

- some patchy fog tonight

- heavy rain should stay south Wednesday night

- warm and humid airmass with thunder and heavy rain possible
Saturday and Sunday

&&

Discussion...(this evening through next tuesday)
issued at 323 PM EDT Tue Jun 18 2019

A surface cold front moves east from Wisconsin into lower
Michigan overnight but shower activity should be limited and with
the loss of diurnal heating by the time it reaches our northwest
zones, instability is also rather limited, so thunder chances are
very low. We do have the potential for some fog tonight as winds
will be light and surface dew points are creeping up a bit ahead
of the front.

The front pushes south during the afternoon and a sfc low rides
along it tomorrow night. The heavy rain threat still bears
watching for our far southern forecast area, but most model
guidance has continued to keep the heavy rain axis to the south
across northern Indiana and Ohio.

After a brief respite, we'll see another period of active weather
over the weekend with a sfc warm front bringing the chance for
thunderstorms Saturday morning. There are some indications of mesoscale convective system
formation at this time as well, so specific details on how and
where the convection evolves through the weekend are quite murky.
What we are fairly sure of is that the heavy rain threat will
again be with US into early next week with the sfc low moves off
to the northeast and cooler and drier airmass returns, probably by
Tuesday.

&&

Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 723 PM EDT Tue Jun 18 2019

Patchy fog will once again be a local issue tonight. We do have
many sights going down to MVFR in the forecast but local sub IFR
looks possible.

A few showers could start moving in from the northwest late
tonight...but a greater risk exists on Wednesday. The atmosphere
does become unstable in the afternoon so we will need to monitor
the risk for an isolated thunderstorm. The wind fields look weak
so any storms should be moving slowly.




&&

Marine...
issued at 323 PM EDT Tue Jun 18 2019

Winds and waves should remain below 25 knots and 4 feet through
Thursday. There will continue to be areas of fog at times. Some
heavier rain is possible south of Grand Haven on Wednesday night.



&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...none.
&&

$$

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