Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 190007
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
807 PM EDT Thu Apr 18 2019

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 324 PM EDT Thu Apr 18 2019

- Showers move out this evening, and come back overnight

- Trend for rain showers on Saturday to be further east

- Another chance of rain late Sunday into Monday

- Good deal of uncertainty for next week

&&

.DISCUSSION...(This evening through next Thursday)
Issued at 324 PM EDT Thu Apr 18 2019

Main feature initially this afternoon is the cold front that is
making it`s way toward exiting the SE corner of the forecast area.
The cold front is distinct with a narrow line of convection, void of
lightning so far. A small chance of thunder remains ahead of the
front near Jackson for the next hour or two with a couple hundred
j/kg of CAPE available.

The rest of the area is seeing light rain showers around, with
little consequence, other than it being a damp and ugly day. All of
this is associated with a wave and associated low level jet that is
riding up and along the front. The short term and hi res models all
indicate that the rain showers will move out steadily over the next
2 to 4 hours as the front moves east, and the waves moves out.

The break in the rain will be somewhat short, especially for SE
areas. That is because yet another wave will be moving NE along the
front. This wave will be much further SE, and we will be on the NW
periphery of the system. This scenario will keep the deep and rich
moisture out of the area. It still looks to be a cool and dreary day
for all but the NW corner of the area toward Ludington on Friday.
Winds will pick up which will make it even more unpleasant. We do
expect that almost all of the precipitation will be rain, as the
coldest of the air with the upper low should stay away from the
area.

The trend for Saturday has been a bit more optimistic, with models
trending toward a further SE solution of the final low lifting out.
The far SE portion of the area toward Jackson could still still some
light rain, but most of it should be across SE Michigan and beyond.

We are looking at a push of the warmer air moving into the area on
Sunday, which could be accompanied by some light rain showers. This
should not be much at all, as we will not have moistened up much at
all by that time. We then get into the warm sector through much of
Monday, before showers, and maybe a few storms come in late as the
cold front approaches.

There is quite a bit of uncertainty for mid week next week after the
front moves through late Mon/early Tue. It all revolves around the
upper low in the Plains states, and how quick the Mon/Tue system
moves by. The various range of solutions is affected by the timing
of the upper low lifting out/opening up, and the speed of the
Mon/Tue system. We could end up dry for a couple of days if the
Plains low closes off, or wet if it lifts out quicker. Plenty of time
to monitor the latest trends.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 807 PM EDT Thu Apr 18 2019

Ceilings will generally be in the 1000 to 1500 foot AGL range this
evening with some areas blo 1000 feet. This will be most common
across central and eastern Lower Michigan. Those areas may have
IFR conditions much of Friday as rain and low clouds persist
there.

Northwest winds around 10 to 15 knots will go north overnight and
increase to near 20 knots with gusts to 30 knots at times on
Friday.

&&

.MARINE...
Issued at 324 PM EDT Thu Apr 18 2019

We issued another Small Craft Advisory for the entire nearshore
earlier, and will be keeping it as is for this forecast. Winds will
come up later tonight, last through Friday night, and possibly into
Saturday. It appears that the gales that will be widespread
offshore, should stay just offshore of the marine zones.


&&

.HYDROLOGY...
Issued at 324 PM EDT Thu Apr 18 2019

Wet conditions will continue into tonight and Saturday mainly for
areas south and east of a line from Mount Pleasant to South Haven as
precipitation shifts east. Through this period rain totals ranging
from 0.10" to 1.00" are expected with the highest totals near
Jackson and Lansing. This rain may briefly result in heightened
river water levels near Jackson and Lansing. No significant river
flood threat exists in these areas, but if strong rainshowers hit
the same area repeatedly, some local ponding of water is possible in
heavier rain showers. Soils in this area have dried out a bit more
than the rest of lower Michigan in recent days, so significant
issues related to ponding of water are unlikely, but will continue
to be monitored.

Meanwhile rainfall across the Muskegon River basin in combination
with already high river levels due to recent wet weather has
resulted in further rising river levels to just above minor flood
stage. The Muskegon River at Newaygo and Bridgeton is expected to
crest just above minor flood stage tonight and early Friday, before
dropping below flood stage by late Friday and early Saturday,
respectively.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory from 11 PM this evening to 8 AM EDT
     Saturday for LMZ844>849.

&&

$$

SYNOPSIS...NJJ
DISCUSSION...NJJ
AVIATION...Ostuno
HYDROLOGY...ANH
MARINE...NJJ



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