Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 201742

Area Forecast Discussion
National Weather Service Marquette MI
142 PM 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...(Saturday through Thursday)
Issued at 503 AM EDT FRI MAY 20 2016

Expect a slowly progressive pattern as the mid/upper level ridge
over the plains shifts through the Great Lakes and the western CONUS
mid level low over OR lifts to Saskatchewan leaving a broad trough
with wsw flow to the Upper MS valley and northern Great Lakes.
Temperatures will remain above normal with dry weather finally
giving way to increasing shra/tsra chances from Monday into Tuesday
with precipitation potential continuing through Thursday. Until
greater moisture and pcpn arrive, elevated fire weather risks will
be the main forecast concern.

Saturday, A shortwave trough and associated cold front will dive to
the southeast through northern Ontario but the pcpn chances are
expected to remain to the north and east of Lake Superior. Deep
mixing, with 850 mb temps around 10C-12C, will support max temps
into the mid and upper 70s and bring dewpoints down into the upper
30s, at the lower end of guidance. With the relatively dry low
levels, the pcpn produced by the GFS was disregarded.

Sunday, Temps should climb a few degrees as 850 mb temps climb 1C-2C
compared to saturday as RH values again fall into the 20-30 pct
range.  with the sfc ridge moving just to the east of the area late,
expect relatively light winds with lake breezes developing.

Monday, A tightening gradient between the ridge over the eastern
Great Lakes and low pressure over manitoba will result southerly
winds of 10 to 20 mph. With 850 mb winds around 25-30 knots, gusts
should climb into the 20 to 30 mph range, strongest over the west
half. Although low level moisture will be increasing across the
west, another day with min RH values from 25 to 30 pct is expected
over the central and east. With the stronger winds, expect near
critical fire wx values leading to higher wildfire potential,
especially given the extended dry period.

Monday night through Tuesday, The front and axis of higher moisture
will spread across Upper Michigan with PWAT values climbing near 1.4
inches. However, with the blocking ridge to the east, the stronger
supporting qvector conv and upper level div may lift more to the
northeast of the CWA. Although POPs have trended higher compared to
previous forecasts, there is still uncertainty about the coverage
and amounts, especially over the central and east.

Wednesday and Thursday, Additional pcpn may be possible as another
shortwave trough moves out of the plains. However, there is even
greater uncertainty with the position and timing of this feature.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 142 PM 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 through tonight.
Just some high based cu is expected this afternoon. Weak trough
moves across on Sat which will switch winds to NW-N. Winds should
stay less than 10 knots and conditions will remain VFR.

.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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