Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 220645
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
245 AM EDT THU SEP 22 2016

.SHORT TERM...(Today and tonight)
Issued at 245 AM EDT Thu Sep 22 2016

Inverted surface trough remains just west of our CWA early this
morning...extending from Western Upper Michigan thru NW Wisconsin
and SE Minnesota into the Central Plains. Large area of convection
featuring heavy rain continues to fire upstream along this
boundary...with the strongest storms aligned along the 850 mb theta
E ridge within an area of MUCAPES of 2500 J/kg. Closer to home...
far eastern edge of this MCS is trying to nudge into far NW Lower
Michigan attm. Eastward progress has been rather slow...with the
eastern edge tending to erode as it moves away from much better
moisture and instability to well to our west.

Short term models continue to have serious trouble resolving the
evolution of the resulting convective complexes developing along the
inverted trough. All models do generally agree that the eastern edge
of the MCS will continue to erode (to varying degrees) as it pushes
east today. Widespread showers should diminish to scattered to
numerous with eastward progress away from better moisture and
instability to our west along the trough axis. Some limited
instability (MUCAPES of around 500 J/kg) will reach into our CWA
later this morning and this afternoon...so cannot rule out an
embedded thunderstorms. Certainly do not expect any severe potential
given weak instability and weak wind fields. Also appears heavy
rainfall will remain west of our CWA in the vcnty of better moisture
along the trough axis.

Trough axis itself will slowly sag southward tonight...as high
pressure builds southward out of Canada and into Northern Michigan.
Remaining POPs will follow suite...with highest chance POPs and best
chance for embedded storms focused across Northern Lower Michigan.
Again...severe storms are not expected thru tonight. Expect a wide
range of temps today as we remain along the nrn edge of the inverted
trough axis. Afternoon highs will range from the mid 60s across
Eastern Upper Michigan to around 80 degrees near Saginaw Bay. Low
temps tonight will range from the upper 40s in Eastern Upper
Michigan to near 60 around Saginaw Bay.

.LONG TERM...(Friday through Wednesday)
Issued at 245 AM EDT Thu Sep 22 2016

Friday through Saturday night...

High impact weather potential: None expected.

Pattern synopsis/Expected evolution: 120+ kt jet streak is draped
across portions of southern Canada, generally from ~50W westward
through central Manitoba. Cutoff upper-level low across the western
third of the CONUS will is causing a sharp buckle in the jet stream,
which rounds the base of the upper trough near San Diego before
heights rise again over the eastern Pacific Ocean. By Friday night,
the aforementioned upper low shifts toward the Intermountain West
with lee side surface cyclogenesis ongoing across NE/SD.  Guidance
suggests not much movement through the remainder of the week in
terms of the baroclinic zone currently taking shape over the area
tonight. However, an expansive area of high pressure is expected to
sink south from Canada, allowing dry air to dominate the northern
Great Lakes through at least Saturday.

Friday - Friday night: Any lingering light scattered showers,
generally south of M-32, continue to diminish in coverage as northern
Michigan lies on the southern periphery of an expansive area of high
pressure centered over northern Ontario allowing for a dry east-
northeast wind to dominate. Will go ahead and remove all PoPs CWA-
wide for the afternoon hours, but despite decreasing PoPs, it could
still end up to be a rather brisk early fall day with highs topping
out in the mid 60s, occasionally gusty winds, and slow-to-clear
skies.

Saturday - Saturday night: Isentropically driven precip along the
stationary frontal boundary draped across the northern Great Lakes
tries to clip western parts of the area as it slides northeastward
from Wisconsin. Will opt to keep the area dry as the 22/00z guidance
suite has become more consistent in deep layer dry air overhead
preventing approaching echoes from reaching the ground. The next
threat for precip arrives very late Saturday night with the approach
of a more impressive cold front, still tied to low pressure spinning
over the northern plains/ southern Manitoba; however, beyond
Saturday night confidence diminishes in terms of if/when the cold
front actually crosses the area.

Sunday through Wednesday...

Rather low confidence exists through this timeframe with several
feasible solutions through the start of next week. Not sold that
Saturday night`s approaching cold front actually makes it completely
through northern Michigan prior to retrograding as hinted at by the
ECMWF, all thanks to deep longwave troughing over the Intermountain
West and a secondary wave that develops over Texas and intensifies
as it rides northward along the cold front before retrograding west
as a renewed warm front. Certainly an interesting feature to keep an
eye on as we get closer to the start of next week. One thing that is
for sure - no truly cold air in sight through the extended period
and beyond!

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1145 PM EDT Wed Sep 21 2016

No surprise, but precipitation and lower cigs have been slow to
arrive given all forcing and instability remaining well upstream.
Still think this will change heading through the early morning,
with that still upstream convective complex completing the
saturation process. This will eventually lead to some lowering of
cigs and light rain reaching all taf locations by sunrise. MVFR
producing cigs advance slowly south today and this evening,
targeting KPLN much of the day, arriving at the other sites during
the evening. Trends are definitely supporting less thunder
potential, so will continue to leave out of the forecast. Light
and mostly variable winds through this forecast period.

&&

.MARINE...
Issued at 245 AM EDT Thu Sep 22 2016

Winds and waves will remain below SCA criteria thru this evening...
but will begin to approach criteria late tonight into Friday as
winds shift to the NE and strengthen in response to the trough axis
sinking southward and high pressure building in from the north.
Chances of showers and thunderstorms will increase today...but
strong to severe storms are not expected.

&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

SHORT TERM...MLR
LONG TERM...Gillen
AVIATION...MSB
MARINE...MLR



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