Area Forecast Discussion
Issued by NWS Gaylord, MI
FXUS63 KAPX 290127
Area Forecast Discussion
National Weather Service Gaylord MI
927 PM EDT THU JUL 28 2016
Issued at 927 PM EDT Thu Jul 28 2016
Evening water vapor loop reveals a short wave moving across
southern Wisconsin. Some semblance of a mid level deformation axis
stretches across central lower Michigan and back through central
Wisconsin, which has been producing spotty showers through much
of the day and into the evening, although coverage has largely
diminished save for one cluster of showers drifting eastward out
of the Green Bay area. Further south, modest instability resides
through the lower Great Lakes where several clusters of storms
have come and gone over the last several hours, bolstered by
daytime heating and subtle short wave forcing. Much of the
thunderstorms have fizzled except for a cluster of storms south
of Ann Arbor.
Rest of tonight into Friday: Short wave will slowly slip into the
lower lakes region dragging deformation axis slowly southward into
lower Michigan, while surface high pressure and dry air wedge into
the northern Great Lakes. But modest forcing through tonight will
keep a low end threat for showers going for areas south of M-72,
particularly near lake Michigan with that aforementioned cluster
of showers coming out of Green Bay. No thunder anticipated with
nearly all instability confined to the lower lakes.
.SHORT TERM...(This evening through Friday afternoon) Issued at
322 PM EDT Thu Jul 28 2016
Tonight and Friday...will generally remain dry across the northern
Great Lakes through the period with seasonal temperatures. The only
chance of rain within the cwa through Friday afternoon will be this
evening as a band of showers lingers between Manistee and Saginaw
Bay...and again overnight as an upper trough approaches.
Current sfc chart and regional observations showing large area of
high pressure over central Canada and the northern Plains...while a
weak sfc boundary sinks into the Ohio Valley. The latest short term
model data continues to push high pressure into the Great Lakes
through the overnight period...before becoming centered over the
state on Friday. At upper levels...a trough associated with a 500mb
low over Quebec...will drop into the northern Great Lakes tonight
and early Friday. 850mb temps in this upper flow drop to between 12c
and 13c this evening...then to around 10c and 12c Friday.
Temperatures in this pattern will be nearly seasonal across northern
Michigan with highs on Friday in the upper 70s to around 80 degrees.
At first...precipitation chances seem limited as model soundings and
mstr progs show drying settling in across nrn Michigan this evening.
However am a little concerned about rain showers redeveloping over
the srn cwa this evening and overnight...as short term high res
models continue to show some mid lvl mstr lingering over the srn cwa
(pwat values near 1 inch, 850mb dew pts around 12c) through 06z.
Also...850/500mb qvectors showing good convergence over portions of
lower Michigan this evening into the overnight hours in advance of
approaching upper trough. Current sat and radar data showing some
rain showers occurring over the Dakotas in vicinity of this
approaching upper trough. Therefore have added a chance of rain
showers til around 06z over the srn portions of the cwa.
.LONG TERM...(Friday night through Thursday)
Issued at 322 PM EDT Thu Jul 28 2016
(7/29)Friday night...In the evening, it looks like the rain should
be south of M-55 as the core of the sfc ridge is over Lake Superior.
There is a series of shortwave trough in the 500 mb flow and with
the sfc and 850 mb moisture trying to move north as a sfc low begins
to develop in the Ohio Valley, there looks to be chance for some
showers, and possibly thunderstorms, along the M-55 corridor and
then into the southeast counties overnight, mainly on the ECMWF.
This run of the ECMWF is less developed with the sfc low, so think
that the ECMWF is having some feedback issues. However, will keep
some pops in with our neighbors.
(7/30)Saturday...High pressure and dry air eventually work their way
into the the rest of N Lower during the day, and force the rain
south of M-55 as the trough axis moves east of Michigan by 00z. The
500 mb heights begin to rise as the sfc High begins to ridge in a
little more. The sfc and 850 mb moisture look a little "dirty"
overnight, but with the subsidence from the building 500mb heights,
will expect that the night should remain quiet.
(7/31)Sunday...High pressure continues to control the weather in the
Upper Great Lakes producing mostly sunny skies, at least that`s the
consensus of the models. The GFS does have some moisture and qpf up
the I-75 corridor during the afternoon, but think that the GFS is
over doing the sfc dewpoints, and thus the instability over the
region. So went to the drier guidance of the ECMWF and the NAM.
Sunday night through Thursday...
Models have shown a transition from a zonal flow aloft to a broad
trough late in the week. The start of the work week will be
dominated by a sfc high centered over Quebec that will ridge back
towards Michigan for Monday into Tuesday. An upper level low in
Northern Manitoba begins to push eastward resulting in warm air
advection ahead of the cold front associated with the sfc low.
With WAA pushing into our CWA models agree with an above average
week of highs with increased pcpn towards late week.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 732 PM EDT Thu Jul 28 2016
Subtle troughing remains across the Great Lakes this evening with
a short wave working across Wisconsin. This feature has helped
kick off several clusters of showers from central and southern
Wisconsin across central and southern lower Michigan. Several
clusters of thunderstorms are also ongoing across the lower Great
Lakes where better instability resides. To the north, high
pressure and drier air is slowly building across the northern
Tonight through Friday, overall VFR conditions will persist at the
terminal sites although there will be a low end chance for a few
showers at TVC and MBL tonight. High pressure and drier air
wedges into northern Michigan for Friday and will end the shower
Winds: North to northeasterly through Friday and largely under
sustained 10 knots.
Issued at 322 PM EDT Thu Jul 28 2016
Winds and waves are expected to remain below small craft advisory
criteria through the forecast period...as a large area of high
pressure slowly settles south into the state. The chances for rain
showers continues this evening and overnight...as an upper trough
pushes across the Great Lakes region.