Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 270824

Area Forecast Discussion
National Weather Service Marquette MI
424 AM EDT WED JUL 27 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 250 PM EDT TUE JUL 26 2016

Upper air pattern consists of a shortwave across MN and the ern
Dakotas this morning that will move across the area this afternoon
into early evening. Nam shows some 850-500 mb q-vector convergence
over the area through 00z Thu with another shortwave affecting
mainly the southern cwa on Wed.

Couple things going against the convection for this afternoon. KMPX
and KGRB 12z soundings show dry mid levels and also the possibility
with sfc heating this afternoon mixing out the dew points in the
lower levels in the afternoon with sfc dew points falling in the
afternoon. This appears to be the case as sfc dew points have been
slowly falling and mixing out this afternoon which will tend to cut
down the instability this afternoon and because of this, have cut
the pops down a bit and delayed them a bit as well. Models also show
the strongest shear to the northeast with less instability and more
instability with less shear to the southwest of area. We cannot seem
to get everything to come together, so this argues for cutting pops
a bit. Still have chance pops in though for late this afternoon into
this evening in case some convection gets going on the lake breeze
boundaries which would be a possibility with lake breeze
convergence. Still kept in some chance pops in for Wed across the
south as well as a shortwave goes by to the south of the area and
have it dry to the north. Overall, did not make too many changes to
the going forecast for temperatures or weather.

.LONG TERM...(Thursday through Tuesday)
Issued at 424 AM EDT WED JUL 27 2016

As advertised by medium range guidance late last week, weak troffing
will develop into the Great Lakes region and se Canada over the next
few days, but 500mb heights will only fall to around normal for late
July. This will spell a more comfortable period of weather for the
Upper Great Lakes with temps overall around normal to slightly blo
normal thru the end of the week. Early next week, heights will be on
the rise again as a ridge builds into the Great Lakes in response to
a trof developing into the Pacific NW. Latest GEFS shows 500mb
heights rising to 1.5 standard deviations above the long term early
Aug avg over the Upper Lakes by Tue evening. So, another round of
very warm, humid weather is in the offing early next week. Looks
like it may be relatively short-lived as medium range guidance is
indicating a progressive pattern across southern Canada that will
push the Pacific NW trof thru the Upper Great Lakes mid to late next
week. Looking farther ahead, CPC/NAEFS outlooks favor above normal
temps for the area in the 8-14 day time frame. However, NAEFS
outlook does have a large area of near to blo normal temps across
much of Canada, so cooler air could slip into Upper MI at times. As
for pcpn, a dry period is shaping up as sfc high pres dominates the
area late week on the backside of the weak troffing. The dry weather
could then very well persist thru early next week due to the
mid/upper ridge building over the area. The next best chance of pcpn
would then occur around mid week as the Pacific NW trof approaches.

Beginning Thu, sfc high pres will be more firmly building into the
Upper Great Lakes, pushing cold front well s toward the Ohio Valley.
There will be some cloud cover to start the day across the southern
fcst area on the backside of a shortwave and associated shra/tsra
moving across WI/lwr MI. Otherwise, expect a mostly sunny, more
pleasant day with highs in the 70s and dwpts finally falling into
the more comfortable low/mid 50s across the area. N to ne wind to
start the day and then meso high developing over Lake Superior in
the aftn will result in coolest conditions near Lake Superior.
However, with sfc water temps into the 60s across southern Lake
Superior, the cooling power of the big lake is loosing its punch.

With clear skies, light winds and precipitable water one-half inch
or less Thu night, favored the low side of avbl guidance, especially
over the w half under sfc high pres ridge and lowest precipitable
water. Traditional cold spots will fall down into the 40s, perhaps
as low as the lower 40s. Temps will range up to around 60F along
Lake Superior.

High pres will be over the area on Fri, allowing lake breezes across
the board. Fcst soundings suggest cu development in the interior,
especially where the Lake Superior and Lake MI lake breezes meet.
High temps will be similar to Thu, but a little warmer near Lake
Superior. Mins Fri night will be similar to Thu night, but with
precipitable water a little higher, lowest mins should not be as low
as Thu night.

With high pres slipping a bit to the e on Sat, Lake Superior lake
breeze won`t move as far inland. Slight increase in 850mb temps will
result in max temps Sat being a couple of degrees higher than Fri
for most locations. Temps will be up around 80F away from the

Sun-Tue...steady warming and an increase in dwpts will occur under
slowly rising heights and low-level s to sw flow. By Tue, expect
high temps into at least the mid/upper 80s. Can`t totally rule out
isold convection if any shortwaves emerge from the Pacific NW trof.
At this point, influence of high pressure and anticyclonic flow
should maintain dry conditions into at least Monday. Shra/tsra
chances should begin to increase Tue into Wed.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 131 AM EDT WED JUL 27 2016

VFR conditions continue through the forecast. There remains a slight
chance for showers and possibly thunderstorms late tonight into
Wednesday morning at KIWD and possibly a few showers at KSAW with
the passage of a disturbance to the south of the area. KIWD has the
higher probability for TSRA there but even this is quite low, so
included only VCTS in forecast there and included a few hours of
VCSH at KSAW. KCMX deeper into the drier air so do not expect any
precipitation there.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 250 PM EDT TUE JUL 26 2016

Winds across Lake Superior for the remainder of the week should be
mostly 15kt or less as the pressure gradient remains on the weak
side across the Upper Great Lakes.

Upper Michigan...
Lake Superior...
Lake Michigan...


LONG TERM...Rolfson
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