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fxus63 kgrr 151748 
afdgrr

Area forecast discussion
National Weather Service Grand Rapids Michigan
148 PM EDT Mon Jul 15 2019

Latest update...
aviation

Synopsis...
issued at 330 am EDT Mon Jul 15 2019

- a round of warm frontal thunderstorms expected this
afternoon/evening.

- Tropical moisture brushes Southern Lower Michigan tues into Wed.

- Heat expected this week, especially thurs-Sat

&&

Discussion...(today through next sunday)
issued at 330 am EDT Mon Jul 15 2019

First order of business is addressing the threat of thunderstorms
this afternoon and evening. Models have been fairly consistent in
showing convection this afternoon. The new trend has been for the
models to be a bit more bullish in coverage. High resolution models
like the namnest and the href ensemble indicate a Lake Shadow with
the bulk of the precipitation occurring inland from The Big Lake.
Expecting convection to fire around the noon hour and slowly
progress to the east through the afternoon. Fairly solid coverage
looks to occur from the 131 corridor to the east. Bulk shear is not
impressive around 20-25 knots at best, so we are likely look at
multi-cells with localized zones of gusty winds. Lapse rates are not
favorable for hail, but precipitable water values approaching 2 inches will result
in torrential downpours. So, biggest concerns with convection today
are locally gusty winds to 45 mph and locally heavy rain.

The next time frame of concern will be Tuesday afternoon into
Wednesday morning as the moisture associated with the former
tropical system lifts through the Ohio Valley. Models have been
consistent in shearing the system out to the east off to our south.
We could see some more persistent showers/storms make it into the
Interstate 94 corridor Tuesday into Wednesday putting down totals in
the half inch to one inch range, especially towards jxn.

The forecast looks to trend toward drier and hotter as we head into
the end of the work week and into the weekend. The warmest days look
to be Thursday, Friday and Saturday with 850mb temps in the 21c to
24c range each afternoon. This would push high temperatures into the
90s. Our high temperatures have nudge up a bit especially Friday and
Saturday into the low 90s. We may have to look at heat headlines
down the Road after days of heat indices that may push towards 100.

&&

Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 144 PM EDT Mon Jul 15 2019

The atmosphere has become unstable and a few showers have
developed. It is forecasted that the scattered showers will turn
into thunderstorms as the move inland. Thus many of the tafs will
feature a thunderstorms in the vicinity for the next couple of hours. Less in the way of
shower activity is forecasted later this afternoon and into
tonight as the atmosphere stabilizes somewhat.

Then tonight a lower cloud deck is forecasted to move in. Right
now we will lower the ceilings into MVFR category...but there is a
risk for IFR.




&&

Marine...
issued at 330 am EDT Mon Jul 15 2019

Southwest winds of 10 to 20 knots will build waves to 1 to 3 feet
north of Holland today. Southwest winds will increase a bit tonight,
possibly gusting over 20 knots at times. Waves will likely peak
around 3 feet tonight up near big and little Sable points. Tuesday
and Wednesday, winds and waves look to be on the lighter/smaller
side with a weaker pressure gradient in place.



&&

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

$$

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