Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 190545
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1245 AM CDT TUE JUL 19 2016

.UPDATE...
Issued at 824 PM CDT Mon Jul 18 2016

Brought in mention of patchy fog from the Brainerd Lakes region to
the Park Falls area. Last few runs of the HRRR/RAP bring dewpoint
depressions within 3-5 deg at the surface between 08-11Z. This
combined with clear skies and light winds will result in patchy
fog development overnight. The rest of the forecast is on track.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 355 PM CDT Mon Jul 18 2016

Relatively quiet short term period as surface high pressure
drifts over the upper midwest and into the western Great Lakes
region through Tuesday. There is a weak thermal boundary
draped across central Minnesota and northern Wisconsin this
afternoon. Latest RAP analysis is showing some pooling of dew
points along the boundary which corresponds to the increase in
cloud cover across these zones. The high resolution models are
trying to kick off isolated convection along this boundary this
afternoon and into tonight. However, confidence is low in enough
support/forcing to get showers going. Will continue to monitor for
any development through the afternoon but at this time plan on
keeping forecast dry through Tomorrow.

The mid level ridge axis will pass over the forecast area tomorrow
afternoon...bringing an transition to return flow and increasing
850hPa temps.

.LONG TERM...(Tuesday night through Monday)
Issued at 355 PM CDT Mon Jul 18 2016

Main concerns for this forecast package are the potential for
dangerously warm conditions Wednesday and Thursday, and the chance
of thunderstorms.

An upper level area of high pressure will be centered over the
Central and Southern Plains Tuesday evening...with a broad ridge of
high pressure extending north across the Northern Plains and
Canadian Prairies. A very hot and muggy airmass will be found under
the ridge and will intensify through late this week. Heat indices
Wednesday afternoon and again Thursday afternoon will be in the
upper 90s to low 100s across portions of the Northland. Onshore flow
near Lake Superior should keep temperatures a little cooler for
adjacent portions of northeast Minnesota and northwest Wisconsin
during this period. Also the light southerly flow over the Arrowhead
should help keep humidity and temperatures a bit cooler. Confidence
seems high enough this afternoon to hoist an Excessive Heat Watch
from Walker and Cass Lake to Phillips and Park Falls. We may meet
criteria farther north and east, however confidence is much lower in
those areas due to the potential for convection and cloud cover,
along with the affects of the lake breeze.

Several shortwave troughs will ripple through the flow Tuesday night
through Saturday evening, yielding periodic chances of showers and
thunderstorms. With abundant moisture available along the periphery
of the ridge, heavy rainfall is possible. However, amounts will be
considerably lower than what was experienced last week. Due to the
uncertainty in the development and location of storms, it`s
difficult to pinpoint which areas are under the greatest threat for
heavy rain with this forecast package.

The ridge is forecast to flatten as a potent shortwave pushes
through the region Friday night and Saturday, bringing relief from
the very warm temperatures. Another round of showers and
thunderstorms is possible late Sunday night and Monday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1245 AM CDT Tue Jul 19 2016

Generally expecting VFR conditions with high pressure moving
through. Radiation fog has developed and expect fog overnight due
to clear skies and light wind. Uncertain on how low visibility
will get, but think the lowest visibilities will be in the IFR
range. Held off in mentioning fog at KDLH/KINL. Will see a return
to VFR after fog dissipates. May see showers and storms late
Tuesday afternoon into the evening. The latest guidance is all
over the place on timing and placement of convection. Due to
uncertainty left in as VCSH as a wave is moving in and there is
strong warm air advection.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  54  79  64  86 /  10  10  40  50
INL  52  84  68  91 /  10  10  40  20
BRD  59  85  71  90 /  10  10  50  20
HYR  55  85  69  88 /  10  10  50  50
ASX  54  74  65  88 /  10  10  40  50

&&

.DLH Watches/Warnings/Advisories...
WI...Excessive Heat Watch from Thursday morning through Thursday
     evening for WIZ006>009.

MN...Excessive Heat Watch from Wednesday afternoon through Thursday
     evening for MNZ025-033>036-038.

LS...None.
&&

$$

UPDATE...WL
SHORT TERM...Graning
LONG TERM...Huyck
AVIATION...WL


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