Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 152225

Area Forecast Discussion
National Weather Service Grand Rapids MI
625 PM EDT Tue May 15 2018


Issued at 330 PM EDT Tue May 15 2018

Fair weather will return tonight through mid to late week as a
high pressure ridge takes hold of the weather pattern. Seasonably
mild temperatures are forecast for the rest of the week with high
temperatures in the 70s daily. The next chance for rain and
thunderstorms will come Saturday night through Sunday.


Issued at 625 PM EDT Tue May 15 2018

A few isolated showers, on with a top near 20,000 ft near Rockford
have developed on the lake breeze convergence boundary. There is
just enough instability to get cumulus clouds tall enough for
showers near the lake breeze convergence boundary and this is
shown nicely on the latest Hrrrx (last few actually). These
shower will be gone by sunset. Since one of them actually has
moderate to heavy shower under it I updated the grids to show the
most likely area for them over the next hour or two.


.SHORT TERM...(This evening through Thursday night)
Issued at 330 PM EDT Tue May 15 2018

Short term fcst concerns are minimal. An isolated light rain shower
or sprinkle may still develop late this afternoon into early evening
with very weak instability in place (latest mesoanalysis shows
around 250 j/kg or less of sb/mu cape over our fcst area). This
notion is supported by the latest HRRR. Otherwise skies will be
partly cloudy overnight and northeast to east winds will advect a
drier airmass in.

A high pressure ridge will bring fair wx with seasonably mild temps
Wednesday through Thursday. High temps both days will reach the
middle 70`s to near 80 degrees. The nam cu scheme shows potential
for some sct fair wx cumulus tomorrow and Thursday afternoon.

With a weak gradient in place tomorrow under the ridge we expect a
lake breeze to develop early in the afternoon and push inland which
will result in a wind shift to the west and allow skies to become
mostly clear.

.LONG TERM...(Friday through Tuesday)
Issued at 330 PM EDT Tue May 15 2018

The pattern is looking rather quiet for the long term.  Models are
showing on relatively weak wave of low pressure to track through the
region later Saturday night through Sunday.  The mid level pattern
features a positively tilted trough tracking through.  850 mb moist
advection will feed this system somewhat...supporting at least some
showers.  Overall the risk for thunder is relatively low.

A surface ridge of high pressure will be in place for Friday into
Saturday of this week.  Subsidence associated with this feature
should support dry conditions.  High pressure is forecasted to move
in for Monday behind the departing wave of low pressure and will
likely persist into the middle part of the week.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 132 PM EDT Tue May 15 2018

Clouds that develop this afternoon will likely be on the MVFR/VFR
line. The heating today could trigger a couple of storms. Right
now it looks like KGRR would be the most likely to see on. So I
put VCTS in the forecast for a few hours after 21z. Other than
that...VFR is expected. I would not rule out some patchy fog later
tonight...but a drier northeast to east wind is predicted. Onshore
winds are expected to develop this afternoon near KMKG.


Issued at 330 PM EDT Tue May 15 2018

Northerly winds will produce wave heights in the 2 to 4 foot range
late this afternoon into this evening. Wind speeds and wave
heights will subside tonight as high pressure builds in. Minimal
winds and wave heights are forecast through midweek with high
pressure in place.


Issued at 146 PM EDT Tue May 15 2018

One to two inches of rain fell across the Kalamazoo River basin in
the last 24 hours...with lesser amounts in the Grand and Muskegon
basins.  This has increased the forecast crest for rivers in that
system and/or pushed the time of crest out further in time.

River flood warnings continue for the Sycamore at Holt, Grand at
Jackson, and Portage at Vicksburg.  Some of the other sites that are
seeing strong rises could flirt with flood stage...but forecast
trend is for them to crest lower with each issuance so will not
issue any other warnings at this point.

Scattered showers and thunderstorms this afternoon should not have
the areal coverage or intensity to produce rainfall/runoff that will
impact area rivers.  Dry weather for the rest of the work week will
allow runoff to complete and the flood crests to move downstream
without further enhancement.




SHORT TERM...Laurens
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