Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 250352
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1152 PM EDT Thu May 24 2018

.UPDATE...
Issued at 957 PM EDT Thu May 24 2018

A wing of warm-advection forced showers has poked into eastern
upper MI. This is falling out of a mid-cloud deck, and with some
drier air below, radar is somewhat overstating precip coverage and
rates. Still, Soo Canada has been reporting raindrops at times.

Main cluster of deep convection is progressing across western
upper MI, propagating east. This is an accompanied by an axis of
weak instability (MuCape 500j/kg) folding across upper MI with
time. Will boost pops in eastern upper MI overnight, with a few
embedded (non-svr) t-storms. Pops still dwindle rapidly as one
heads south, with nothing south of M-32.

Minor adjustments to temps (did lower a smidge in n central and ne
lower MI).

&&

.NEAR TERM...(Through Tonight)
Issued at 331 PM EDT Thu May 24 2018

...Some showers and non-severe storms tonight...

High Impact Weather Potential...A few thunderstorms in eastern upper
Michigan. Severe storms are not expected.

Pattern Synopsis/Forecast...Upper level ridge axis continues to
slowly build into the western Great Lakes this afternoon.
Downstream surface high pressure remains over the central Great
Lakes but is beginning to edge off toward the mid Atlantic coast.
Surface low pressure is slipping out of Canada into the northern
plains/upper Midwest region with some semblance of a warm front
arcing down through Minnesota/Iowa. In between, southwest return
flow is pulling more warmer, more humid (and unstable) air into
the far western Great Lakes, curling across the U.P. into eastern
upper Michigan where there is some actual instability this
afternoon. Lower Michigan remains somewhat shielded by the lake
with dewpoints running a good 5 to 10 degrees lower, with no
instability.

Primary Forecast Concerns...shower and thunderstorm chances
tonight.

First off, batch of showers and some thunderstorms from earlier in
the day continue to slip across upper Michigan, toward the eastern
U.P. Convection has been diminishing upon reaching a more stable
environment downstream, but will need to be addressed early on.
Already added shower chances to the forecast for the balance of
the afternoon into early evening.

After that, surface low will ease into the upper Midwest as we go
through tonight with some semblance of a cold front slipping into
the northern/central plains. Best forcing/instability and main
focus for showers and storms will remain upstream, from the
Midwest into the central Plains. That said, deeper moisture/instability
plume will continue to fold into the western Great Lakes through
the night. Coupled with a modest LLJ developing and nosing across
the Upper Peninsula, will maintain scattered showers and perhaps
some thunderstorm possibilities across the U.P. through the
course of the night, and just into the tip of the mitt. No severe
weather anticipated.

&&

.SHORT TERM...(Friday through Sunday)
Issued at 331 PM EDT Thu May 24 2018

...Weekend rain chances...

High Impact Weather Potential: Scattered thunderstorms, especially
Friday evening, and in the afternoon Saturday and Sunday

Pattern Synopsis/Forecast: High amplitude ridging that has been
building over the eastern CONUS will be dampened by a shortwave that
has been moving out of the Desert Southwest. This shortwave will
move over the area Friday evening and through the day Saturday. A
second shortwave moving out of the Pacific NW will follow closely
behind the first disturbance, moving overhead Sunday.

Primary Forecast Concerns: Primary concern remains the potential for
some scattered thunderstorms over the weekend. Still doesn`t look
like a washout by any means, but some afternoon pop-up storms could
cause some inconvenience for the areas they move over. Shear still
looks anemic for any kind of organized severe threat Saturday, with
20kts of 0-6km bulk shear. There are a few areas Sunday with bulk
shear getting into the more preferable 30kt range,  but dewpoints
are likely too high in guidance and producing unrealistically high
CAPE values. Wet bulb zero heights are sub 10kft right now, and mid
level lapse rates will steepen as the trough moves through, so even
pulse type storms could produce some small hail. Will continue to
keep an eye on this and see if things start to look more favorable.

.LONG TERM...(Sunday night through Thursday)
Issued at 331 PM EDT Thu May 24 2018

...High pressure returns...

Building high pressure will bring another stretch of warm days and
quiet weather heading into mid-week. High temperatures will continue
to run well above normal, with much of northern lower getting into
the 80s. Another chance of showers looks to come later in the week,
right now some time Thursday, as the next disturbance moves overhead.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1152 PM EDT Thu May 24 2018

VFR. LLWS overnight and Fri morning.

High pressure is slipping away from the eastern lakes. Sw flow
will increase just off the surface tonight. This will support an
increase in showers/t-storms in upper MI, and perhaps PLN will be
grazed by this activity. Otherwise, just mid/high clouds here in
northern lower MI. Sw winds will be a touch gusty by Fri
afternoon.

&&

.MARINE...
Issued at 331 PM EDT Thu May 24 2018

Winds will continue to pick up this evening in response to a
tightening pressure gradient as high pressure exits the area and low
pressure approaches. Expect southwesterly winds becoming more
southerly Saturday morning, with speeds in the 15 to 20 knot range
lasting into Saturday morning. Scattered thunderstorm development is
possible from Friday evening through Sunday afternoon.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...JZ
NEAR TERM...BA
SHORT TERM...AM
LONG TERM...AM
AVIATION...JZ
MARINE...AM


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