Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 231943
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
343 PM EDT Sat Mar 23 2024

.KEY MESSAGES...

- Won`t Feel Like Spring Tonight

- Rain Monday Into Tuesday

- Dry Stretch of Weather Mid To Late Week

&&

.DISCUSSION...
Issued at 257 PM EDT Sat Mar 23 2024

- Won`t Feel Like Spring Tonight

First off, the snow pack is absolutely being torched today by the
"strong March sunshine." The higher sun angle is working overtime
and the GRR snow depth has gone from 6 inches at 800am this
morning to around 1 inch as of 300pm. What remains of the snowpack
though will aid in providing a cooler than normal night through
radiational cooling processes. Our lows tonight range from the
middle teens along portions of U.S. 10 to near 20 elsewhere.
Normal lows for tonight are in the lower 20s to upper 20s from
north to south so we will be 5 to 15 degrees below normal.

Mainly dry weather is expected until the rain arrives on Monday,
but there is a chance for a bit of light snow Sunday afternoon
into Sunday night in a warm air advection wing of precipitation
ahead of a strong Plains low. This is best seen in an 850mb temp
surge which ramps from -12C near Ludington at 800am Sunday to +1C
by 200am Monday. Not out of the realm of possibilities to see a
light dusting of snow up towards Big Sable Point Sunday. Otherwise
the focus is on rain chances to begin the work week.

- Rain Monday Into Tuesday

Water vapor imagery shows a west coast trough this afternoon with
a mid level shortwave heading for the California coast. This wave
works its way to the Plains states on Monday and is pivoting
northeast through the Great Lakes on Tuesday. At the surface a
deep low forms initially with a depth of around 980mb sliding east
out of Colorado. The low fills as it moves our direction into the
990s on Monday in Iowa and remaining at that depth as it moves
north into Canada on Tuesday.

Rain is forecast to break out ahead of the low and move into Lower
Michigan on Monday. Surface dew points nose up into the upper 40s
ahead of a cold frontal passage on Tuesday. 850mb dew points reach
+4C or +5C. These moisture values are very marginal for thunder,
so we should be just looking at a rain event. Likely rainfall
totals will be in the 0.30 to 0.65 range which is a blend of the
wetter GFS and drier ECWMF. Obviously no hydro concerns with those
totals.

Highs on Monday and Tuesday should push well into the 50s. Around
60 is in the forecast down towards I-94 both days.

- Dry Stretch of Weather Mid To Late Week

High pressure settles in during the Wednesday through Friday time
frame and we should largely be dry. We could be looking at a short
window of lake generated precipitation, including some snow
potential on Wednesday in the wrap around cold air advection
regime.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1247 PM EDT Sat Mar 23 2024

The low clouds that were left over from the system yesterday moved
out this morning leaving mostly clear skies for a brief period.
Now, fair weather cumulus clouds are developing, and will continue
to expand this afternoon. This is not a big concern since ceilings
will be VFR around 4-5k ft. Clouds will be more broken inland, and
more scattered at the lakeshore.

The clouds will dissipate this evening toward sunset, and winds
will go light. Was considering some fog potential with the
melting, clear skies and light winds. However, mid clouds will be
moving in overnight mitigating that threat a bit, along with a dry
air mass. The clouds will gradually thicken up on Sunday, and
lower a bit. They are expected to remain VFR no lower than 6k ft
agl through 18z Sunday and beyond.

&&

.MARINE...
Issued at 257 PM EDT Sat Mar 23 2024

High pressure drifting through the Great Lakes tonight will bring
light winds and a lack of wave action. Those conditions will
persist into the day on Sunday as well as the high drifts east.
Sunday night the game changes a bit as stronger southeast winds
begin to crank up ahead of a fairly deep plains low. The low will
track from Kansas into Wisconsin from Monday into Tuesday. Winds
Sunday night from the southeast will veer to the south on Monday
and eventually southwest on Tuesday.

No headlines needed tonight or Sunday obviously. Sunday night
into early next week though we will need marine headlines in the
strengthening southerly flow. Mixing warm air advection winds to
the surface this time of year is difficult, but given the strength
of the low we are looking at Small Craft Advisories certainly.
Gales are possible and we will be ascertaining which headline is
the correct one as we head into tonight and Sunday.

&&

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

&&

$$

DISCUSSION...Duke
AVIATION...NJJ
MARINE...Duke


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