Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 230730

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 AM EDT Mon Apr 23 2018

Synopsis/Short Term/Long Term/Marine/FireWeather

Issued at 330 AM EDT Mon Apr 23 2018

High pressure will provide another mostly sunny and mild day with
high temperatures near 70. A slow moving low pressure system
tracking south of Michigan will bring clouds and scattered light
rain showers for Tuesday. After today cooler temperatures,
generally in the 50s, will prevail through the rest of the week.


.SHORT TERM...(Today through Wednesday)
Issued at 330 AM EDT Mon Apr 23 2018

No significant changes to the fcst. While some high level
cloudiness will move in from the south today, it should be thin
enough to allow for highs close to 70. Thicker clouds arrive
tonight, with chance pops for light rain arriving late mainly
along and south of I-96. Initial band of showers will probably
get mostly chewed up by our dry air mass, with better risk of
showers on Tuesday once better saturation occurs.

The other player on Tuesday/Tuesday night in addition to the
upper low over the Ohio Valley is a nrn stream trough approaching
from the northwest. Models are hinting at better probability of
showers developing later Tuesday across central and northern Lower
Michigan ahead of this feature. This area should receive more
insolation than srn Lwr MI, so a diurnal component combined with
wk sfc convergence and the apchg wave should result in scattered
afternoon and evening convection. Not forecasting thunder up north
at this time, although models do show a few hundred joules of
MUCape developing at pk heating.

Confidence low regarding departure of the rain threat as new
ECMWF wants to hold onto a shower threat into Wednesday -
especially east of hwy 131. For now will keep Wednesday dry with
decreasing clouds, but may need to add pops in ern sections in
later fcsts.

.LONG TERM...(Wednesday night through Sunday)
Issued at 330 AM EDT Mon Apr 23 2018

A ridge of high pressure will bring fair weather with seasonable
temperatures Wednesday night through Thursday. We did notice that
the 00Z ECMWF now suggests that clouds and even some rain/snow
showers may develop/linger Wednesday night. However this latest
ECMWF run is an outlier among latest medium range guidance
solutions. Therefore we maintained the dry fcst Wednesday night but
will continue to monitor medium range guidance trends.

A low pressure system will move in from the west and bring a chance
of showers late Thursday night and Friday. It is not completely
impossible that some wet snow flakes may mix in with pcpn early
Friday over our northern fcst area.

However this is not the most likely outcome and we continued to
favor the ECMWF solution in which case p-type will be plain rain.
Sfc temps even across our northermost fcst area should stay above
freezing so no winter wx type impacts are expected even if a few wet
snow flakes were to mix in.

A cooler airmass will briefly advect in behind that system Friday
through Saturday when high temperatures will only reach the lower to
perhaps middle 50`s. Temperatures will then undergo a slow
moderating trend late in the weekend into early next week as the
colder air retreats back northward.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 1145 PM EDT Sun Apr 22 2018

VFR conditions will continue at all the terminals through Monday
evening. Winds Monday will become easterly aob 10 kts with nothing
more than sct-bkn areas of high level cloud cover.


Issued at 330 AM EDT Mon Apr 23 2018

Winds and wave remaining below small craft advisory criteria
through Tuesday, then northerly flow ramping up Tuesday night into
Wednesday could necessitate marine headlines.


Issued at 330 AM EDT Mon Apr 23 2018

Will have another day of elevated fire danger today as
temperatures approach 70 with RH values drop into the 20s this
afternoon. Winds may gusts at times to 20 mph during pk heating
when deeper mixing is present.


Issued at 309 PM EDT Sun Apr 22 2018

Lowland nuisance flooding near some riverbanks will be ongoing
over the next few days as water from last weekend`s mixed
precipitation event moves through the river basins. Since no heavy
rain events are anticipated in the next week, rivers will
gradually subside.




LONG TERM...Laurens
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