Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 200649

Area Forecast Discussion
National Weather Service Marquette MI
249 AM EDT FRI MAY 20 2016

.SHORT TERM...(Today and tonight)
Issued at 249 AM EDT FRI MAY 20 2016

Upper air pattern consists of a closed 500 mb low and trough in the
Pacific NW, a ridge in central Canada, a shortwave over the northern
plains, a closed low over the central plains and a closed low in the
Canadian Maritimes. A ridge builds into the plains tonight while the
closed low over the central plains and the shortwave over the
northern plains combine and move across the area this evening. With
airmass being very dry, will continue to go with a dry forecast even
though there are some models that are trying to put out some
convection this afternoon and early evening with lake breeze
boundaries. Looking at upstream soundings from KGRB and KMPX, they
are very dry in the mid levels with an inversion around 700 mb which
should limit any tall cloud heights and cumulus should not be tall
enough to spark any convection. Feeling is the qpf from some models
is overdone and will continue dry. Overall, did not make too many
changes to the going forecast. Will continue to also go with drier
dew points than all model guidance as the model forecast dew points
are way too high and have been that way for several days.
Persistence is the way to go with this forecast.

.LONG TERM...(Friday night through Thursday)
Issued at 421 PM EDT THU MAY 19 2016

Pattern across the conus will become more amplified in the coming
days as a trof amplifies over the far wrn conus thru Sat and forces
a building ridge over the Plains States into s central Canada this
weekend. The Plains ridge will then shift over the western Great
Lakes by Mon as a shortwave lifts out of the western trof. This
shortwave is forecast to eject nw of the Western Great Lakes and
offers the first mentionable pcpn chance over the next 7 days (Mon
night/Tue), but given the track of the energy nw of here, the
potential for much needed widespread, decent pcpn appears low.
Another weaker shortwave may eject out of the western trof after the
first wave bringing additional chcs of pcpn into midweek.

With a pre full-greenup dry spell underway and with limited
evapotranspiration aiding low relative humidity, fire danger will be
on the increase daily. So, while the weather will be quiet into
early next week, fire weather concerns will be growing, especially
with larger fuels now drying out. Mon will likely be the day of
greatest concern due to strengthening winds. Looking farther ahead,
CPC and CFSv2 8-14 day outlooks point toward above normal temps
being favored for Upper MI but the NAEFS 8-14 day outlooks have
trended away from above normal temps.

Beginning Fri night into Sat...Shortwave drops thru northern and
eastern Ontario late Fri night Sat, and associated cold front will
dissipate as it reaches Lake Superior/Upper MI. With low levels dry
and forcing passing well ne of here, no pcpn is expected. Again,
expect some high based diurnal cu, but probably less coverage than
what the NAM soundings are indicating as NAM dewpoints in the upper
40s/low 50s appear overdone. 850mb temps rise 1-2c from Fri, so high
temps Sat will push solidly into the mid/upper 70s over much of the
interior forecast area away from the Great Lakes. For dewpoints,
will continue to favored the lower bias corrected non NCEP guidance,
especially the global Canadian model, to again drop interior min RH
down to the 20-30 pct range.

Sunday...As a surface low pres trough moves out over the western
plains and high pressure slides e on Sun, southerly winds will begin
to increase a little, and 850mb temps will rise a degree or two from
Sat. Away from Lake Michigan, this should support highs mostly into
the upper 70s, perhaps reaching low 80s at some locations over the w.
Once again, favored the lower bias corrected non NCEP guidance for
dewpoints, especially the global Canadian model, to drop interior
min RH down to the 20-30 pct range. Southwest wind gusts reaching
near 20 knots over the far west by afternoon will increase wildfire
potential there given prolonged dry conditions.

On Mon, shortwave that ejects from the western trof will lift ne
toward southern Manitoba/northern Ontario. Associated sfc trof will
approach the Upper Mississippi Valley, resulting in a tightening
pressure gradient over the Upper Great Lakes. With 850mb temps
rising to 14-15C, Mon will be the warmest day with highs in the
upper 70s/lwr 80s away from Lake Michigan. Once again, will favor
the lower bias corrected non NCEP guidance, especially the global
Canadian model, to drop min RH down to the 25-35pct range away from
Lake Michigan. With low RH and winds gusting to 20-30 mph, perhaps
higher given 35-45kt winds at 850mb, Mon will be the most critical
day for fire wx concerns, especially over the west half of Upper MI
where winds will be strongest. Could be some -shra late over the far

Approaching sfc trof will weaken as it moves into the Upper Great
Lakes Mon night/Tue as supporting shortwave lifts well north to
Hudson Bay and mid/upper ridge remains over the Great Lakes, being
held up by the closed mid level low drifting up the Mid Atlantic
Coast. As a result, pcpn will likely diminish and may even fall
apart as the weakening trof arrives. For now, will continue nothing
higher than low chc pops for Mon night/Tue.

Southwest upper flow continues Wed into Thu. With better moisture
forecast over the area and with the potential of a few more
shortwaves lifting through the region, will maintain low chc pops
for shra/tsra.

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 109 AM EDT FRI MAY 20 2016

With dry hi pres dominating the Upper Great Lakes region, expect VFR
conditions and light winds at all the TAF sites this fcst period.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 249 AM EDT FRI MAY 20 2016

A quiet late spring pattern is expected for Lake Superior for this
forecast period with high pressure over the Great Lakes region.
Winds will be mostly under 15kt each day. Winds on Monday will
increase to 20 to 25 knots ahead of a trough lifting through the
Northern Plains and this will be the strongest winds expected in
this forecast.

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


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