Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 131126
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
726 AM EDT Wed Mar 13 2024

.KEY MESSAGES...

- Mild Today

- Showers and Storms Late Tonight Through Thursday Evening

- Trending Colder This Weekend, Snow Possible Early Monday Morning

&&

.DISCUSSION...
Issued at 310 AM EDT Wed Mar 13 2024

- Mild Today

A consensus of latest shorter range high resolution guidance as
well as ensemble numbers suggest that it will be quite mild again
today. High temperatures will again reach well into the 60s given
quite a bit of sun and coming off relatively mild mins early this
morning for this time of year.

- Showers and Storms Late Tonight Through Thursday Evening

The 00Z HREF corroborated with CAMs suggest that showers and
thunderstorms will develop tonight due to isentropic upglide in
conjunction with weak elevated instability to the north of the
warm front. The warm front tonight will extend from west to east
across northern IL/IN/OH to near the MI/IN border by 12Z Thursday.
Any scattered convection should stay near to mainly south of the
I-96 corridor where weak elevated instability will be present.
Further north we expect just more stratiform type scattered
showers. No severe wx tonight given only weak elevated instability
and no sfc based instability.

A better chance for convection across most of our area (and
especially over the southern half of our fcst area) will come
Thursday morning and afternoon as the warm front lifts slowly
north.

Warm frontal position Thursday is key to this fcst in terms of any
svr wx risk. At this time an overall short range guidance
consensus corroborated with the 00Z HREF suggests it will make it
to near or slightly north of the I-94 corridor. This is the area
we will need to monitor for potential for a few marginally severe
storms where there is potential for some sfc based instability to
develop in conjunction with enhanced directional shear.

Indeed it is noted that the spc day 2 conv outlook has a marginal
risk for svr wx near to mainly south of the I-96 corridor.
Further north of this area we just expect scattered showers and
non severe storms with perhaps some small hail given the elevated
nature of convection. In terms of mesoscale analysis we will need
to monitor warm frontal position closely Thursday since there is a
bit of uncertainty on just how far north it and consequently any
marginal risk for svr wx will get.

Latest guidance trends suggest that any lingering showers/storms
Thursday evening will exit our area to the east rather quickly
overnight. In the wake of this system significantly cooler wx is
fcst Friday with brisk nw flow cool air advection.

- Trending Colder This Weekend, Snow Possible Early Monday Morning

A sharp upper trough will drop southeast over the western Great
Lakes Saturday, pulling with it a cold front that should reach the
forecast area on Sunday. Precipitation chances Saturday and even
into Sunday look better than before thanks to these forcing
mechanisms.

By Sunday night, an upper PV lobe looks like it will pivot through
the base of the larger trough, passing just south of Lake Michigan
as it ejects eastward. This would introduce even colder air in the
lower troposphere than previously expected; a sizable majority of
medium range ensemble members now advertise 850 mb temperatures at
or below minus 12C. Conditional instability should be favorable too;
the upper PV lobe will favor extra deepening of the marine boundary
layer amidst broader scale synoptic ascent over the southern Lake
Michigan region.

A look at the cluster analyses indicates most uncertainty is
associated with the timing of this lobe rather than its equatorward
extent. This lends some confidence to some accumulating snowfall
playing out in the Sunday night Monday morning timeframe. All of
this being said, we don`t expect this to be a particularly impactful
event - but it still would be very noticeable given the lack of any
appreciable snowfall we`ve experienced lately.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 726 AM EDT Wed Mar 13 2024

No changes of note for this update. Borderline MVFR fog currently
is being reported at MKG, but this should be short-lived. Outside
of that, solid VFR conditions are expected areawide today. Winds
will be light and often variable in direction, particularly at
the southern terminals including AZO, BTL, and JXN. Precipitation
will start to make inroads after 06Z tonight, but it`s still a bit
too early to include this in the TAFs.


&&

.MARINE...
Issued at 310 AM EDT Wed Mar 13 2024

Winds will gradually veer to the nw and eventually to the ne later
today and will be rather light. As a result minimal wave heights
are forecast. Wave heights will remain rather low tonight and tomorrow
given the offshore component of winds.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Laurens/TJT
AVIATION...TJT
MARINE...Laurens


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.