Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 161152

Area Forecast Discussion
National Weather Service Grand Rapids MI
752 AM EDT Tue Jul 16 2019


Issued at 300 AM EDT Tue Jul 16 2019

- Showers and a few thunderstorms later today

- Hot and humid mid to late this week through the weekend

- More thunderstorms possible late Wednesday night and Thursday


.DISCUSSION...(Today through next Monday)
Issued at 300 AM EDT Tue Jul 16 2019

The remnants of the former tropical system will continue to move
northward into lower Michigan today. As moisture and instability
increase showers and scattered thunderstorms will develop later
today. Showers that are getting better organized will move into
our southern fcst area by mid to late morning. The best chance
for convection will be over our se fcst area this afternoon as sb
cape values will potentially reach around 2000 j/kg.

Any storms could produce very heavy rain due to the influx of
remnant tropical moisture as precipitable water values will reach
2 to 2.25 inches this aftn over our se fcst area which is about
200 pct above normal for this time of year. Severe wx is unlikely
given lack of a strong forcing mechanism for convective
initiation and relatively weak wind fields w/height. In addition
instability could be limited somewhat by all the clouds and
showers rolling into our southern fcst area by mid to late

The big story going forward later this week will be the building
heat and humidity and potential for a legitimate heat wave from
Wednesday/Thursday through at least Sunday. High temps Thur through
Sun could potentially reach well into the 90s.

H7 temps will moderate to 11 to 12 C by Thursday evening through
the rest of the week and weekend (cap) and thus result in a hot
but dry pattern. Until that happens though it does seem there is
potential for one or several rounds of convection to roll through
late Wednesday night and Thursday.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 753 AM EDT Tue Jul 16 2019

Showers today mainly south of a Holland to Lansing line will lead
to ocnl MVFR conditions. A risk for tstms with localized intense
rainfall rates develops for this area this afternoon/evening,
especially 20Z-02Z, which could lead to IFR or lower conditions if
a terminal is impacted by any stronger cells. Showers and storms
diminishing after sunset although areas of fog/stratus developing
after 06Z leading to areas of IFR overnight.


Issued at 300 AM EDT Tue Jul 16 2019

Southwest winds of 10 to 20 kts are forecast today which will
result in wave heights of around 2 to 4 feet with relatively
highest waves up around Big and Little Sable Points. However wind
speeds and wave heights should remain under small craft advisory
criteria today through midweek.




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