Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 201907
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
307 PM EDT Mon Mar 20 2017

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 307 PM EDT Mon Mar 20 2017

After precipitation exits the region early this evening, quiet
weather is expected into Thursday, with highs Wednesday only in
the 30s. Thursday night through the weekend looks wet and mild
with highs Friday getting up into the 60s.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 307 PM EDT Mon Mar 20 2017

Some rain showers are still noted upstream, but both PoPs and
the thunder threat continue to wane. Therefore have trimmed late
afternoon / early evening PoPs even more with this update.

After this evening, there is high certainty for quiet weather
through the period. An unseasonably strong surface high //max
pressure close to 1040 mb// will dominate the area with seasonably
cool temperatures. Model predictability is excellent for these
scenarios, so there is high certainty that we will not see any
impactful weather.

.LONG TERM...(Thursday through Monday)
Issued at 307 PM EDT Mon Mar 20 2017

A soggy period begins Thursday night as sfc high moves east with
overrunning pattern developing. Residual cold air is eroded by
southerly flow but some wet snow could mix in across the interior
northeast zones at the outset of the precip Thursday evening.

A sfc front stalls across Lower Michigan in zonal flow regime on
Friday and Saturday. There could be a sharp temperature gradient
from north to south both of those days, although Friday looks to be
the warmer day as the front is further north. Shallow cold air is
expected across the northern forecast area by early Saturday. There
is even a chance of an icy mix across the far northern zones by
Saturday evening under continued low level cold advection.

Sfc low occludes and weakens by Sunday as it tracks into northern
Illinois with low level easterly flow continuing across Lower
Michigan and shallow cool air inversion probably holding in the low
clouds and drizzle through Monday. Tweaked daytime maxes down from
Saturday through Monday to account for clouds, precip and shallow
low level colder air.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 140 PM EDT Mon Mar 20 2017

Scattered showers and thunderstorms will be across far southern
Lower Michigan this afternoon near AZO...BTL and JXN. MVFR
conditions are expected until around 23Z. Elsewhere we expect VFR
to prevail. Southwest winds this afternoon will go northwest by
this evening and remain at or blo 10 knots.

&&

.MARINE...
Issued at 307 PM EDT Mon Mar 20 2017

Recent WaveWatch3 guidance shows waves exceeding small craft
advisory criteria Tuesday afternoon into evening with strong
northerly winds behind the cold front. Details and exact timing are
still a little fuzzy. A small craft advisory will be needed, but
will let subsequent shift hammer out details with newer model
guidance.

&&

.HYDROLOGY...
Issued at 140 PM EDT Mon Mar 20 2017

Generally 0.05 to 0.25 inches of precipitation fell Monday morning.
Scattered showers could produce similar amounts in portions of the
area this afternoon and evening. Flooding is not expected. Tuesday
through Thursday looks dry. Later this week and into next week,
there are indications of mild temperatures returning and several
rounds of showers and thunderstorms being possible.

&&

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

$$

SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...Ostuno
AVIATION...Ostuno
HYDROLOGY...CAS
MARINE...TJT


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