Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241136
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
736 AM EDT Fri May 24 2019

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 318 AM EDT Fri May 24 2019

- Showers and thunderstorms tonight. A couple of storms could be
  strong/severe.

- Locally heavy rainfall possible.

- More storms possible along/south of I-94 Sunday.

- Stormy Monday night through Wednesday night.

&&

.DISCUSSION...(Today through next Thursday)
Issued at 318 AM EDT Fri May 24 2019

The active weather will continue well into next week. Today will
mainly be dry but a warm front moving north tonight will focus
showers and thunderstorms over the cwa. During this time of year,
warm fronts tend to come alive at night when the low level jet
strengthens. Model consensus is that the warm front will lay across
northern Indiana around 00z and move over the cwa toward sunset.
Moisture convergence increases dramatically from 00z to 06z from
southwest to northeast. Given the lift over the frontal boundary,
I`d expect showers and storms to develop during the evening and
continue overnight with a further focus toward the eastern cwa by
morning. Shear values perk up to 40-50 knots and MUCAPE increase to
around 1k j/kg too. Thus there may be some organization to to a few
of the storms resulting in stronger to perhaps severe storms with
hail the main threat north of the warm front and wind south of the
front. Flooding is a concern too as pwats increase to 1.75 inches.
Some of the storms may produce well over an inch of rain in a short
period of time.

A cold front moves through Saturday night and pushes the storms
south of the cwa. However, a pesky little short wave scoots across
northern Indiana Sunday resulting in showers/storms south of I-94.

Monday morning will be dry but then the frontal boundary moves north
again and the cycle repeats itself. A low in the Plains moves
northeast toward Wisconsin and pushes the the boundary north causing
showers/storms to develop Monday afternoon and continue through
Wednesday night.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 736 AM EDT Fri May 24 2019

I still for the most part believe what I wrote 8 hours ago, the
area of showers will move through our CWA between 13z by MKG and
14z to 15z GRR, AZO, BTL and later LAN and JXN. However unlike
what I wrote earlier, the area of showers is more expansive than I
was thinking it would be. Also there is still some thunder with
these showers, it is not out of the question MKG and GRR could see
a little thunder as this area moves in.

All of this will move out by mid afternoon, so VFR will prevail
but the clouds will not go away, but cloud bases will be above
3000 ft agl.

The second area of showers and thunderstorm will move through
early evening. Thunderstorms should be more widespread than will
so this morning. I would think MVFR cigs should prevail by 06z after
all of that rain falls. Showers should continue through most of
the early morning hours before coming to an end after 12z. It will
likely take till midday Saturday for conditions to go solid VFR
again.



&&

.MARINE...
Issued at 318 AM EDT Fri May 24 2019

Wind and waves will be fairly tame today but begin to increase
Saturday as southwest winds increase to 15 to 20 knots. Waves will
respond by increasing to 2 to 4 feet. Thunderstorms are expected
tonight through Saturday. Wind and waves will be higher during
thunderstorms.


&&

.HYDROLOGY...
Issued at 318 AM EDT Fri May 24 2019

The potential exists for considerable rainfall tonight through
Saturday as showers and thunderstorms develop along a warm front. A
strong feed of moisture will accompany this front. Qpf around  1.25
inches is possible with locally 1.75 to 3 inches on the high end.
Given the wet ground, rivers could be pushed out of their banks;
we`ll keep an eye on this potential.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...04
DISCUSSION...04
AVIATION...WDM
HYDROLOGY...04
MARINE...04



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