Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 230753
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
353 AM EDT Tue May 23 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 409 PM EDT MON MAY 22 2017

WV imagery and RAP analysis indicated a mid/upper level low over
portions of nrn Ontario into the nrn Great Lakes with several weak
shrtwvs rotating around this feature. At the surface, an elongated
low and occluded front was located btwn Lake Superior and James bay.
Vis loop, radar and obs showed abundant low clouds lingering across
Upper Michigan along with some isolated showers or sprinkles through
the cntrl and ern cwa. The -shra were had intensified slightly with
the limited daytime heating.

Tonight, any lingering instability showers should end early this
evening with loss of diurnal heating. As the mid level low pivots
and the stronger qvector conv shifts to the sw of the region,
weak ridging will prevail over Upper Michigan with no pcpn. Expect
enough lingering clouds to keep min temps from the upper 30s to
the lower 40s.

Tuesday, the stronger 700-300 mb qvector conv with the shrtwv
digging into IA will continue to remain to the south of Upper
Michigan. There may still be enough forcing and moisture ahead of
the mid level trough axis along with some weak instability from
daytime heating to support sct -shra over the srn cwa. Otherwise,
temps will remain below normal with highs from the lower 50s near
Lake Superior to thearound 60 south.

.LONG TERM...(Wednesday through Monday)
Issued at 352 AM EDT TUE MAY 23 2017

No high impact weather through the upcoming weekend. May still see
at least one night with frost potential late this week, most
likely Wednesday Night over the west. There will be rain showers
especially over the east half of forecast area Wed and Thu and
over much of the area late Fri into this weekend. However, no
heavy rain is expected with majority of the forecast area seeing
well under 1 inch of rain in the next week per Weather Prediction
Center (WPC).

On Wed, main upper low over the middle Conus will be over the middle
Mississippi river valley but an extension of that trough is over the
Upper Great Lakes. Still looks like mainly eastern forecast area
could see light showers due to h85-h5 moisture and weaker forcing.
Soundings much drier over west half of Upper Michigan so even though
there should be some daytime cu with the cold air beneath the
trough, not expecting any rain there. Wed night into Thu the pattern
changes little with even some slight strengthening of upper level
trough over the area. With the sfc ridge over the west Wed night
kept on low side for min temps and continued to mention frost.
Farther east, lingering q-vector convergence/lift over at least the
eastern forecast area if not even into the central forecast area.
GEM led the way on this as it was the only model showing this a few
days ago. Now the GEM is joined by the GFS and ECMWF. Seems the main
question is how far west this rain will reach. For this forecast
chance pops will extend as far west as Munising and Manistique but
if trends continues the rain chances may need pushed even farther
west.

With the slower departure of the troughing on Thu, looks like only
prospects of sneaking in a couple dry days is fading fast. Probably
best shot of dry weather is over western forecast area on Thu and
then maybe the central and eastern areas on Fri. Sfc ridge and at
least some thinning of clouds could lead to min temps late Thu night
falling back into the 30s, but probably not low enough for any
noteable frost. GFS looks a bit too fast in bringing showers over
majority of forecast area on Fri. Prefer GEM and ECMWF which bring
weaker lift and increasing h85-h7 moisture into west half. Not much
MUCAPE to support thunder so still looks like better thunder chances
will be to west of Upper Michigan where some sfc based CAPE is
forecast. If the quicker idea is right then there would be small
chance of thunder Fri aftn over western U.P. Even with the increased
clouds and possible rain, h85 temps warming to around 10c would
support warmest temps this week on Fri with some areas interior west
half reaching lower 70s.

Upper trough moving from the northern Plains to the Great Lakes
region this weekend will bring more unsettled weather. Wave ahead of
main upper low will bring cold front through early in the weekend
then shower chances increase again late in the weekend as main upper
low settles overhead. Unfortunately the unsettled weather pattern
and rather cool conditions with highs only in the 50s to mid 60s
looks to prevail for Memorial Day as well.
&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 633 PM EDT MON MAY 22 2017

MVFR conditions will develop again with cooling overnight and
additional moisture advection. Winds will also be light enough to
allow fog formation that may drop vsby to IFR for a short period
Tuesday morning. SAW will go up to VFR with mixing during the day on
Tue.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 409 PM EDT MON MAY 22 2017

A low pres trough lingering over the area will maintain fairly light
winds across the lake through Tuesday. Winds under 20 kts should
then be the rule into Fri as a relatively flat pres gradient
dominates the Upper Lakes.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLB



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