Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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865
FXUS63 KGRR 132335
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
635 PM EST Wed Nov 13 2024

.KEY MESSAGES...

- Rain Tonight and Thursday

- Chance of showers on Sunday

- Stronger system possible Tuesday/Wednesday

&&

.UPDATE...
Issued at 635 PM EST Wed Nov 13 2024

The forecast remains on track from the previous discussion. The
onset of rain may be delayed slightly due to the dry air in
place, but once we saturate rain will continue through Thursday.

&&

.DISCUSSION...
Issued at 350 PM EST Wed Nov 13 2024

- Rain Tonight and Thursday

Some minor tweaks to timing of POPS moving in this evening,
otherwise no changes to the previous forecast. Leading edge of
rain is currently across central Ill/Ind and moving north. It will
be reaching the southwest zones around 23Z. Upper level
divergence courtesy of a coupled jet structure will have deep Gulf
inflow to work with and storm total QPF of 0.75 to 1 inch is
expected before the center of the low jumps to the East Coast.

Once that happens on Thursday afternoon, the steadier rains are
expected to diminish to showers and some lake-enhanced rain bands
as drier air starts advecting in from the north.

- Chance of showers on Sunday

While there may be a lingering rain shower that lasts into Friday,
we should see mostly dry conditions for Friday and Saturday. Ridging
will be building over the area in the wake of the system moving
through tonight and Thursday. There looks to be just a few lake
effect rain showers that persist right near the lakeshore with the
flow from the NNW. These will end by later Friday, and give way to
dry conditions that will continue through Saturday.

The amplified, yet progressive upper air pattern will keep systems
moving across the CONUS. A large long wave trough coming into the
western portion of the country will be the next system up for the
area on Sunday. The models are suggesting that a low will cutoff
over the desert SW, and the northern stream of the jet will progress
across the northern tier of the country. This will move in for the
Sunday time frame. If the branches of the jet indeed split, the
moisture for the northern branch will be meager without a connection
to the Gulf.

This system will move out quickly by Monday, allowing for another
dry day, with only slightly cooler temperatures in its wake.

- Stronger system possible Tuesday/Wednesday

The upper low that is forecast to cut-off from the long wave trough
later this week, is forecast to eventually be picked up by another
long wave trough moving onshore over the Western U.S., and be lifted
NNE toward the region. If this occurs, this system will draw quite a
bit of Gulf moisture northward with it, and bring a much better
chance of widespread rain to the area. This would likely happen in
the Tuesday/Wednesday time frame.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 635 PM EST Wed Nov 13 2024

VFR conditions will gradually deteriorate as rain moves in from
the southwest. Low level wind shear will also be present with the
low level jet over the western half of the area mainly between
3-6Z. As the low pressure system advances expect ceilings to drop
to IFR values from 6-12Z from west to east. MVFR visibilities are
also likely looking at current visibilities upstream. Low
ceilings, reduced visibilities, and rain continue through the day
Thursday.

&&

.MARINE...
Issued at 350 PM EST Wed Nov 13 2024

Offshore winds through Thursday will generally remain below 25
knots with waves 2 to 4 feet. Both winds and waves will be higher
out at the 5 mile mark and less near the shore.

&&

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

&&

$$

UPDATE...RAH
DISCUSSION...Ostuno/NJJ
AVIATION...RAH
MARINE...Ostuno