Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KMQT 181949

Area Forecast Discussion
National Weather Service Marquette MI
349 PM EDT Tue Oct 18 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 349 PM EDT TUE OCT 18 2016

Water vapor imagery and RAP analysis show wsw flow extending from
the Great Basin to western Quebec. Pair of strong shortwaves that
brought the shra/tsra and heavy rainfall to parts of Upper Michigan
last night are over Quebec, powered ene by 120kt upper jet. Shallow
moisture behind these systems and the low sun angle at this time of
year allowed low clouds to persist over much of the area this
morning. Even this aftn, it`s been a slow process clearing the
clouds with only the sw portion of the area now seeing mostly sunny
skies. A few -shra have even developed recently in Delta and sw
Schoolcraft counties where some sunshine has resulted in a little

During the short term, broad shortwave trof moving across the
western CONUS will begin to sharpen up as it moves out over the
western Plains on Wed. Meanwhile, a separate trof over Manitoba will
shift over northern Ontario on Wed as well. As these changes occur
at the mid levels, very gradual caa will drop 850mb temps that are
currently 6-7C down to around 0C over the Keweenaw to 4C over the se
fcst area by 00z Thu. With western Lake Superior water temps roughly
down to around 10c, lake effect pcpn won`t be a concern during the
short term. Couple of weak shortwaves and an associated sfc trof may
generate a few -shra or sprinkles. Given the overall weak forcing
and lack of deep moisture will leave pcpn out of the fcst. However,
there are some -shra in ND this aftn, so it`s certainly not out of
the question that there could be some -shra/sprinkles late tonight
and Wed. Temps on Wed will still be above normal over the e half of
the fcst area with highs in the upper 50s/lwr 60s. Over the far w,
highs will be around 50F into the lwr 50s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 343 PM EDT TUE OCT 18 2016

Upper trough is forecast to deepen late this week from the middle
conus to the Great Lakes. Conditions will turn cooler across Upper
Michigan with daytime temperatures falling a little below normal in
the 40s Thu-Sat. Normal highs are upper 40s to lower 50s. Temps at
about 5kft or h85 should be around -4c to -6c. Those h85 temps with
Lk Superior water temps 8-13c will result in delta t/s 12-19c which
is sufficient for some lake effect precipitation. Best chance for
precip will be Thu night into Fri morning as deeper moisture arrives
and inversions rise up to 7-8kft. Additional support for precip will
be from at least weaker shortwave energy moving through and uptick
in low-level convergence as sfc trough works across Lk Superior and
northern Upper Michigan. Low-level flow looks more cyclonic than it
did 24 hr ago, so overall the setup will be favorable for light to
perhaps moderate lake effect. Location of strongest, persistent
convergence is subject to change but attm looks like would affect
north central Upper Michigan on Fri morning. Ptype in this area
should remain rain with close proximity to warmer Lk Superior waters
and as 1000-850mb thickness remain above 1300m and sfc temps stay
aoa 38-39F. Farther inland west, wbzero heights blo 1000agl and sfc
temps aob 35F would support some snow mixing in with the rain, but
attm the overall coverage and intensity of precip for these areas
looks minimal.

Mean trough then deepens further over Quebec and the northeast conus
through the weekend while nw flow aloft continues across the Great
Lakes. Still uncertainty on how weekend works out. Even though axis
of mean trough will be well to the east and heights will try to rise
some, there may be additional shortwaves digging across area serving
to keep at least weak troughing in place. Any upper level system
working through will be moisture starved though as deep moisture
will be wrapped up in strong low spinning over Quebec. Just slight
chance pops for the weekend into early next week with temps around

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 144 PM EDT TUE OCT 18 2016

Drier air has been slower to reach KCMX than expected today. Back
edge of lower clouds is currently near the western shoreline of the
Keweenaw, but is being held up by the upslope westerly flow. Should
see low MVFR conditions break out to VFR there around 20z. May see a
period of MVFR cigs at KSAW over the next hr or two before shallow
moisture is pushed/mixed out. Other than these initial lower
conditions, drier air mass settling into the area will lead to VFR
conditions being the rule at KIWD/KCMX/KSAW.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 343 PM EDT TUE OCT 18 2016

Expect winds to remain 20-25 kts or less through the rest of the
week and into the weekend as a relatively weak pressure gradient

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


SHORT TERM...Rolfson
MARINE...JLA is the U.S. government's official web portal to all federal, state and local government web resources and services.