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fxus63 kgrr 260022 
afdgrr

Area forecast discussion
National Weather Service Grand Rapids Michigan
822 PM EDT Tue Jun 25 2019

Latest update...
update

Synopsis...
issued at 1210 PM EDT Tue Jun 25 2019

- thunderstorms, possibly some strong this evening

- dry and warmer Wednesday

- a series of convective events Thu into Mon as storms top the
upper ridge to our west

- warmest week of the year so far this week

&&

Update...
issued at 821 PM EDT Tue Jun 25 2019

Just canceled the watch. The broken line of convection pushing
through the eastern cwa may still be capable of producing 50 mph
winds. Skies will clear after the precipitation ends.

Updated wx and pop grids to reflect current trends.

&&

Discussion...(this evening through next tuesday)
issued at 331 PM EDT Tue Jun 25 2019

We are watching a convective complex heading for Southern Lake
Michigan this evening. The system is tracking mostly to the east
but the best instability is is near and south of I-96. The mid
level lapse rates are high enough for some hail and there is
enough deep layer shear to keep it going into mid evening. The
severe threat is near and south of I-96 and near and west of
US-131 till around 10 PM this evening. While the thunderstorms
will have very heavy rain assoicated with them they will be
moving quickly so I do not see flooding as significant threat at
this point.

Once that system gets out of the area by late evening (with a
weak cold front trailing it), high pressure builds in behind so we
get a nice weather for Wednesday.

Unsettled weather follows Thursday through at least Monday. An
upper low over the southwest Continental U.S. Is forecast to be sheared out
by the next upstream Pacific system . The question is where does
it go? This matters because most the shortwave energy is now
forecast to ride over the top of the western ridge that builds
into the central Continental U.S. By Thu into Fri. This puts southwest
Michigan in a wave train of convective system. The models do not
have a great handle on this and I would expect our forecast to
become much wetter with time for this coming weekend. It will be
Summer like too with temperatures well into the 80s in the
afternoon and dew points into the mid to upper 60s.

&&

Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 723 PM EDT Tue Jun 25 2019

There is a line of thunderstorms with wind gusts in the 30 to 40
knot range crossing our taf sites as I write this. Once this line
clears the area I expect skies to clear. I expect clear skies and
lighter winds on Wednesday.



&&

Marine...
issued at 1210 PM EDT Tue Jun 25 2019

Based on both web cams and buoy observations I have allowed the
Small Craft Advisory and beach hazard to expire. The wind and
waves were greatest (from buoy obs) in the 3 am to 9 am time
frame). It does seem the winds will increase this afternoon over
our northern surf zones for a time but that will not be enough to
result in another Small Craft Advisory. The winds look like they
will be lighter Wed into Fri so more than likely not need a Small Craft Advisory
then either.



&&

Hydrology...
issued at 1210 PM EDT Tue Jun 25 2019

Water from the heavy rains last week are moving through the river
systems. The vast majority of the rivers have crested and begun to
fall. The crest on the Grand River is passing through the Grand
Rapids area today, with water levels now beginning to fall from Ada
to Comstock Park. The river is hovering near flood stage in these
lower parts of the Grand River, but is not expected to result
in significant flooding.

The next few days will provide a bit of relief as the threat of
widespread heavy rain is a bit lower. However, localized heavy rains
will be possible each of the next several days, and with soils
saturated all around west Michigan, ponding water and overflowing
small streams can't be ruled out in a few isolated locations. All it
would take is a slow-moving thunderstorm or several thunderstorms
tracking over the same areas over the course of a few hours.

Heading into this weekend, the overall weather pattern remains
unchanged, and could feature rounds of thunderstorms every day or
two. While widespread river flooding is not expected, this
continuing wet pattern will make it hard for the rivers to drop even
to the average levels for this time of year.

&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...none.
&&

$$

Update...04
synopsis...wdm

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