Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Graphics & Text | 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 241104

Area Forecast Discussion
National Weather Service Marquette MI
704 AM EDT SAT SEP 24 2016

Issued at 557 AM EDT SAT SEP 24 2016

Showers over western Lk Superior getting a bit too organized to just
have slight chance pops over western cwa this morning. Blend of HRRR
and ESRL HRRR and RAP suggest showers continue east where h7-h5 RH
is maximized and on edge of stronger h85 warm air advection. Showers
then slide ene across the Keweenaw Peninsula rest of this morning.
Now even some potential for rain as far east as north central Upper
Michigan this morning. Main change for now was to increase pops
across Keweenaw to likely. Just looking at a few hundredths of rain
but certainly enough to get the ground wet. Placed chance pops over
rest of western cwa next few hours and based on radar trends did
bring slight chances to the ncntrl before they lift out across Lk
Superior. No change to slight chances along WI border. Tweaked temps
down through the morning with the higher rain chances and thicker
cloud cover. Still expect skies to try to clear some possibly by
early aftn over the west half.

.SHORT TERM...(Today and tonight)
Issued at 349 AM EDT SAT SEP 24 2016

Sharp upper level confluent northwest flow is present aloft over the
Great Lakes this morning between sharp ridge over central Conus and
broad trough over eastern Canada. Warm and moist air ahead of strong
Upper low over CO/WY is driving clusters of shra and tsra from
western KS and Neb and also over the western Dakaotas into southern
Manitoba where h85 warm air advection is strongest. The confluent
flow is resulting in large area of sfc high pressure from northern
Manitoba to the Upper Great Lakes. Even with the sfc high nearby,
mid and high clouds are increasing in the warm air advection pattern
aloft. Enough moistening/isentropic ascent on the 305k sfc /800-
750mb/ from northern MN to far western Upper Michigan and northern
WI to support light echoes on the regional radar and multiple obs
are showing light rain is indeed occurring under some of these
echoes. Strongest h85 temp advection remains northwest of Lk
Superior today so once the isentropic ascent and mid level moisture
begins to wane expect the sprinkles or light showers to do the same.
Have small pops over west/southwest through 14-15z then have it dry
the rest of the day with minimal additional forcing and mid levels
drying out. Mostly cloudy this morning but could see filtered
sunshine this aftn. H85 temps bounce up over 10C over the west
though looks like we will only mix to 900-875mb. Overall expect
highs in the mid-upper 60s but could see low 70s over the west.

Center of sfc high slowly moves east tonight as low pressure system
in the plains this morning /tied to the upper low/ lifts toward
southern Manitoba by daybreak on Sun while occluded front crosses
northern MN. Upper level ridge axis remains over Upper Michigan most
of the night while upper trough crosses the Dakotas. A lot of dry
air around in low levels so think the interior central and east
could see temps into the 40s inland where winds try to decouple. 50s
elsewhere as clouds increase and as southeast to south winds stay up
ahead of the front. Forecast soundings did not look promising for
any rain to reach far west by 12z Sun. However, when looking at
where the shra/tsra are occuring this morning on edge of higher h7-
h5 RH/higher pwat and fact this gradient of moisture will be pushing
over far west cwa 09z-12z tonight did bring chance pops to the far
west at that time. SI/s also nearing 0c so retained slight chance of
tsra. A lot of tsra is occurring this morning on the moisture
gradient so feel good about having at least a small mention in there
late tonight. Over most of the rest of the cwa though it should stay
dry though at least 12z with the lingering ridging aloft and dry low-

.LONG TERM...(Sunday through Friday)
Issued at 317 AM EDT SAT SEP 24 2016

Nam has a trough in the northern and central plains 12z Sun with a
shortwave ridge over the upper Great Lakes and ridging in the
western U.S. The trough moves east into the upper Great Lakes Sun
night into Mon and then moves into the lower Great Lakes Mon night.
Deeper moisture and 850-500 mb q-vector convergence arrive on Sun
and last through Sun night with Mon having the wraparound part of
system affecting the area. Did not make too many changes to the
going forecast and have likely pops overspreading the cwa Sun into
Sun night and then chance pops on Mon with wraparound part of storm
coming through.

In the extended, GFS and ECMWF are showing much better agreement at
96 hours with both having a closed 500 mb low east of Lake Superior
in Ontario 12z Tue and ridging into the Rockies and southern plains.
By 12z Wed, the trough is over the lower Great Lakes and the ridge
is into the Plains. The 500 mb ridge then builds into the upper
Great Lakes 12z Thu into Fri. Confidence is now a bit higher due to
better agreement between the GFS and ECMWF now. Temperatures look to
be above normal for this forecast period. Also looks a bit drier now
starting Wed afternoon through Friday.

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 702 AM EDT SAT SEP 24 2016

A few showers are expected at KCMX this morning. Otherwise, should
see scattered to broken VFR clouds today and tonight. Next chance of
rain arrives late tonight at IWD as low pressure system and frontal
boundary approach from the west. Conditions should drop to MVFR
at all the TAF sites on Sun as rain spreads over Upper Michigan.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 349 AM EDT SAT SEP 24 2016

East to southeast winds less than 20 kts today, then southeast winds
increase Tonight into Sun as high pressure moves toward Quebec and
New England and a low pressure system lifts across Mantioba to
northern Ontario. Winds may gust as high as 30 kts Sun into Sun
evening over north central and eastern sections of Lk Superior. The
low will move east of the region Mon into Tue and a cold front will
cross Lk Superior. Winds shifting to the west-northwest will
increase to 20-25 kts on Mon and could reach 30 kts Mon afternoon
into Mon night. Northwest winds to 25 kts continue on Tue then winds
diminish to 20 kts or less by Wed as high pressure crosses the
Great Lakes.

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


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