Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 261350

Area Forecast Discussion
National Weather Service Gaylord MI
950 AM EDT Wed Jul 26 2017

Issued at 949 AM EDT Wed Jul 26 2017

Band of heavier showers tied to low level jet has now
largely pushed off to our east. Lighter rains advancing across
eastern Wisconsin and central upper Michigan, with a much more
robust area of showers/thunderstorms across central Wisconsin. These
latter rains tied to the actual cold front, which will make slow
southeast progress into our area this afternoon and evening. Do
think this current upstream activity will largely fade with time,
waiting for arrival of the actual front and some diurnal instability
development to perhaps kick off some additional afternoon and
evening showers and thunderstorms. Given current cloud trends and a
well worked over atmosphere, afternoon instability should remain
minimal, precluding any type of severe threat. Given excellent
precipitable water values (near one and three quarters of an inch on
local 12z sounding) and a decent warm cloud depth, any storms that
do form could be efficient rain makers.


.NEAR TERM...(Today through Tonight)
Issued at 350 AM EDT Wed Jul 26 2017

...Showers and storms through tonight...

High Impact Weather Potential...Periodic thunderstorms will impact
the region through tonight. A few stronger storms possible...severe
risk low.

Pattern Synopsis/Forecast...Overnight surface/upper-air/satellite
analysis reveals a compact short wave and attending surface low
rolling through central and northern Ontario. Trailing cold front
extends down through Minnesota and continues to secondary low
pressure in the central plains. Plume of moisture/instability
extends northeastward ahead of the front up through the western
Great Lakes and just starting to nose it`s way into the
northern/western parts of the CWA early this morning. Several
clusters of showers/storms continue to develop along the advancing
moisture gradient...and have substantially increased in coverage
in the last few hours across the northern lakes region and back
through northern/central Wisconsin in response to an increasing
low level jet leaning into the region.

Several rounds of showers/storms are on tap through tonight.
Parent short wave and surface low will track into western Quebec
through tonight as trailing cold front folds down across the U.P.
through the afternoon...then sags down through northern lower
Michigan tonight. As mentioned above...clusters of showers/storms
have increased substantially across the northern Great Lakes
region and back through northern/central Wisconsin just in the
last few response an increasing low level jet acting
on the incoming moisture plume. Convection is lining up to move
through a good portion of the CWA over the next several hours and
thus plan on having fairly high PoPs for most areas. Precip may
thin out for a time heading into the the low level
jet relaxes. But suspect we see renewed development this afternoon
across northern lower Michigan and particularly down toward
Saginaw Bay as we warm/destabilize a bit...with showers/storms
lingering into tonight as the front sags down through the region.

Primary Forecast Concerns...Severe thunderstorm potential through
tonight. Respectable 0-6 KM bulk shear values supportive of
organized updrafts will be in place today...particularly this
morning through midday as a core of 50 knot mid level winds
punches across the northern lakes. However...overall instability
remains on the modest side...with an axis of elevated MUCAPE
(just pushing 1000 J/KG) nosing across the region this morning and
MLCAPE values only reaching around 500 J/KG through the day.
Certainly could see a few stronger storms owing to the decent
shear profiles. But latest SPC DAY ONE outlook has kept us out of
the higher severe thunderstorm risk categories today and
tonight...which looks reasonable.


.SHORT TERM...(Thursday through Friday)
Issued at 350 AM EDT Wed Jul 26 2017

...Isolate showers Thursday morning improving weather going into
the weekend...

High Impact Weather Potential...none

Pattern Synopsis/Forecast...Models show the main sfc trough running
from the sfc low near ILX to Saginaw Bay to the low in Quebec. The
ECMWF shows light rain lagging back in N lower, while the GFS is a
little further south. However, by 18z/Thu, the rain is out of the
forecast area. The sfc high builds into the region and another 500
mb shortwave trough looks to be moving into the Upper Great Lakes
overnight. It looks potent enough for rain to come into the region,
but not sure. There is little moisture at 850 mb and especially in
the 700-500 mb layer. This also has implications for Friday as the
models begin to kick off rain showers under the low around 15z/Fri,
but the feature is out of the region by 00z. So think that it should
remain dry, but this is lower confidence idea. However, it looks
like it does dry out by 00z/Saturday and remains so Friday night.

Primary Forecast concerns...As mentioned above, the 500 mb
low/shortwave trough moving through becomes the main concern. The
consensus model doesn`t pick up on it, while the GFS and ECMWF would
suggest that there would be low chance or slight chance pops on
Friday as the low moves through. Best guess is that since the models
don`t have the rain in the same places as its counter part, that
blending of the models washes out the pops for the rain. This will
need to be watched. However, this would only dampen a few locations
around the forecast area.

.LONG TERM...(Friday night through Tuesday)
Issued at 350 AM EDT Wed Jul 26 2017

...High pressure looks to dominate the weekend...

High Impact Weather Potential...Elevated fire weather conditions
possible for Saturday and Sunday but it is a low chance probability.

Extended (Saturday through Tuesday)...Saturday and Sunday will
continue dry with the high pressure over the region. Sunday night,
the GFS shows a cold front moving through with light rain, while the
ECMWF is dry with high pressure continuing over the region. The
blend of the consensus model brings chance pops on Monday as the
front moves through, while the ECWMF continues to be dry with high
pressure and that remains through Tuesday. The GFS dries out post
frontal. So Tuesday is looking dry for the time being.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 647 AM EDT Wed Jul 26 2017

Round of showers and some non-severe thunderstorms will roll
through northern lower Michigan this morning. Conditions are and
will remain largely VFR...but brief periods of MVFR weather is
possible with some of the heavier showers/storms. Precip thins out
mid to late morning. But expect additional showers and storms to
move through the region this afternoon into early evening.
Difficult to nail down timing of TSTMs this afternoon/early
evening at this expect later amendments.


Issued at 350 AM EDT Wed Jul 26 2017

Gusty south-southwesterly winds will impact the region today...
particularly the nearshore areas of Lake Michigan. Small craft
advisories will remain in place through the day into early evening
for northern Lake Michigan. Winds veer northerly and diminish
quickly tonight and will remain on the lighter side through


MI...BEACH HAZARDS STATEMENT until 8 PM EDT this evening for MIZ015.
LM...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LMZ323-341-
LS...SMALL CRAFT ADVISORY until noon EDT today for LSZ321.


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