Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241107
AFDGRR

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

LATEST UPDATE...
Aviation

.SYNOPSIS...
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.

&&

.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 be...so 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.

&&

.MARINE...
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 setup...so its not
certain to happen.


&&

.HYDROLOGY...
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
distances.

&&

.GRR Watches/Warnings/Advisories...
MI...Beach Hazards Statement from 11 AM this morning to 5 PM EDT this
     afternoon for MIZ037-043-050.

LM...Small Craft Advisory until 5 PM EDT this afternoon for
     LMZ847>849.

&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...EBW
AVIATION...MJS
HYDROLOGY...63
MARINE...MJS



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