Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241515

Area Forecast Discussion
National Weather Service Grand Rapids MI
1115 AM EDT SUN JUL 24 2016


Issued at 253 AM EDT Sun Jul 24 2016

An area of low pressure will track through the Great Lakes region
today and tonight resulting in showers and thunderstorms at
times. High pressure will move in behind the departing system for
Monday and Tuesday. This will result in a return to the dry
weather. Overall the temperature will remain above normal into the
middle part of the week.


Issued at 1100 AM EDT Sun Jul 24 2016

At 15Z KGRR radar trends continue to show a large area of rain and
scattered convection across most of our fcst area. Convection
earlier this morning only produced gusts in the 30 to 40 mph range
and no severe reports. Sfc based instability is weak given
extensive cloud cover and showers.

A small area of strong convection west of Ludington and Pentwater
will continue to move east and will produce frequent lightning...
brief heavy rain and perhaps some small hail and strong wind gusts
as it moves onshore in the next hour. This convection will affect
areas mainly near to north of a line from Pentwater to Mt.
Pleasant during the next 1-3 hours.

We expect scattered showers and a few thunderstorms to continue
to develop this afternoon given strong 1000-850 mb moisture
transport and decent elevated instability. However outside of
strong to marginally severe cells west of KLDM attm the severe
weather threat this afternoon looks low and very marginal given
extensive cloud cover and very little sfc based instability.
Stronger storms will continue to bring heavy rain with
precipitable water values way up in the 2-2.25 inch range and
strong 1000-850 mb moisture transport.


.SHORT TERM...(Today through Tuesday)
Issued at 253 AM EDT Sun Jul 24 2016

The main change to the forecast was to increase pops today. One
MCS was track through Southern Lower Michigan at this time. This
will result in increase rainfall for places like
Kalamazoo...Battle Creek and Jackson. Meanwhile a southwesterly
low level jet was pushing through WI. This feature will advect in
abundant moisture as it pushes through Southwest Lower Michigan
this morning. So it appears that the convection upstream of
Muskegon will fill in as it approaches. A small risk for severe
this morning...but instability is somewhat limited.

Depending on how much sun we see for the remainder of the day will
largely determine how much if any strong to severe storms we see
later today. The mid to upper level wave moves in the the cold
front pushing down from the northwest. There is clearing out ahead
of this feature in parts of WI and MN that should track into
Southwest Lower Michigan today. Based on developing instability
and increasing shear...there appears to be a risk for a few severe
storms this afternoon or evening.

.LONG TERM...(Tuesday night through Saturday)
Issued at 253 AM EDT Sun Jul 24 2016

Tuesday night looks dry with zonal flow in the upper levels and
ridging/weak flow still in place in the low and mid levels of the
atmosphere. Rain chances increase on Wednesday as both the ECMWF and
GFS show a shortwave approaching from the Upper Midwest. The GFS
features a stronger wave persisting a bit longer into Thursday, but
there is consensus on broad, longwave troughiness late in the week.

Rain and thunderstorm chances will be highest Thursday into Friday
with the surface low moving through the region, but it`s still much
too early to try to get more precise with the timing of convection.
High temperatures will gradually fall from the mid-upper 80s on
Wednesday to the lower 80s for Friday and Saturday.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 703 AM EDT Sun Jul 24 2016

Aviators should monitor the latest forecasts as several rounds of
storms are possible and then we could see fog tonight.

One area of thunderstorms will track through the TAF sites this
morning resulting in impacts. IFR and lower looks possible with
the stronger cells.  There is also a potential for a wind shift.

This afternoon there will be a break in the convection. However
the atmosphere will destabilize...and this should help to trigger
additional storms. I was not confident enough on how solid the
line of storms will the TAFS featured a VCTS period this
afternoon or evening.

Fog could develop tonight. IFR could result. For now we are
featuring mostly MVFR conditions.


Issued at 253 AM EDT Sun Jul 24 2016

Will go ahead and issue a Small Craft Advisory and Beach Hazards
for part of today. A low level jet will move in this morning. Thus
the wind will increase. The longer fetch supports the region north
of Muskegon. Will need to monitor areas further south as well. The
convection this morning could alter/enhance the its not
certain to happen.


Issued at 1256 PM EDT Sat Jul 23 2016

No river flooding is expected through next week. Up to three
quarters of an inch of precipitation is possible tonight into
Sunday night. A small chance of rain is also in the forecast
Wednesday through Friday. River levels are at or below normal for
this time of year, so this rain should not bring any rivers near
flood. Strong thunderstorms could produce localized rainfall
totals over 1 inch and lead to localized ponding of water.
Rainfall totals will probably vary substantially over short


.GRR Watches/Warnings/Advisories...
MI...Beach Hazards Statement until 5 PM EDT this afternoon for MIZ037-

LM...Small Craft Advisory until 5 PM EDT this afternoon for



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