National Weather Service Raw Text Product

875 
FXUS63 KGRR 181930
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 PM EDT Thu Jul 18 2019

LATEST UPDATE...
Synopsis/Discussion/Marine

.SYNOPSIS...
Issued at 330 PM EDT Thu Jul 18 2019

- Heavy rain potential late tonight

- High humidity and heat through Saturday

- Much cooler and less humid next week

&&

.DISCUSSION...(This evening through next Thursday)
Issued at 330 PM EDT Thu Jul 18 2019

MCS finally moving out of the forecast area with clearing on the
back side which will allow temperatures to reach the 80s by 
sundown across most places. We still should fall well short of 
heat warning criteria, but the headline was left in effect given
the cumulative effect of a long period of 70 plus dew points. 

Synoptic scale analysis shows upper ridge will remain anchored 
south of Lower Michigan through Saturday and the big question mark
continues to be the extent of future MCS activity the next couple
days. Best guess is that we will see another area of convection 
form across central Wisconsin overnight and track east into the 
northern forecast area late tonight into Friday morning as shown
by most model guidance. This makes physical sense with expected 
diurnal enhancement of low level jet in that area and with zonal
flow given the flat ridging. MBE vectors show potential for
backbuilding and training of storms which mean the flood potential
is high given PWATS over 2 inches and efficient warm rain
processes expected.

The MCS may turn southeast Friday morning as some expansion of the
cold pool is expected given thermodynamic processes as dry wedge
exists at mid-levels. This has the potential to again put a damper
on the high temperatures across the central and southern forecast
area on Friday afternoon.

Hot weather looks more likely Saturday across the southern half of
the forecast area as the upper ridge builds into this area and 850
and 925 mb temperatures peak. Then the cold front slides south
during the evening with strong storms and heavy rain potential.
Rain continues into Sunday as sfc wave moves through with much
cooler and drier weather next week under Canadian surface high
pressure.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 143 PM EDT Thu Jul 18 2019

Strong winds in the wake of the area of showers and thunderstorms
across southern Lower Michigan will continue to bring strong
southwest winds with gusts above 25 knots from MKG eastward to 
near GRR and LAN this afternoon. Further south gusts will not be
as strong but will be above 20 knots at times. Showers and
thunderstorms will move east this afternoon but then redevelop
tonight with local areas of IFR at times in the heavier storms.

&&

.MARINE...
Issued at 330 PM EDT Thu Jul 18 2019

Small Craft Advisory is unchanged. There could be areas of marine
fog Friday night and Saturday morning as winds decrease.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Excessive Heat Warning until 8 PM EDT Saturday for MIZ056>059-
     064>067-071>074.

     Beach Hazards Statement through Friday evening for MIZ037-043-
     050-056.

     Heat Advisory until 8 PM EDT Saturday for MIZ037>040-043>046-
     050>052.

LM...Small Craft Advisory until 8 PM EDT Friday for LMZ846>849.

&&

$$

SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...Ostuno
MARINE...Ostuno