Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 211752

Area Forecast Discussion
National Weather Service Duluth MN
1252 PM CDT Fri Jul 21 2017

Issued at 1233 PM CDT Fri Jul 21 2017

Update for new 18z Aviation Discussion below.

UPDATE Issued at 650 AM CDT Fri Jul 21 2017

Update for new 12Z Aviation Discussion below.


.SHORT TERM...(Today through Saturday)
Issued at 420 AM CDT Fri Jul 21 2017

At 4 AM, regional radar depicted a small area of showers and
thunderstorms along the border with Canada, generally in the
vicinity of Lake of the Woods. This area of showers and storms was
moving east along the border region, and should roll into
International Falls. Elsewhere, we were seeing an increase in high
clouds across the CWA. There was some patchy fog across the area
as well. Temperatures ranged from the middle 40s in the interior
portions of the MN Arrowhead, to the mid to upper 60s in the
Brainerd Lakes region, and in a few places near Lake Superior.

Severe weather is the main focus for today through Saturday. The
latest Day One Outlook from the Storm Prediction Center has a
portion of our area in an Enhanced Risk of severe thunderstorms
this afternoon and evening. This area basically includes our
southwest corner of the CWA, including the Brainerd Lakes region
and east central Minnesota. Buffering the Enhanced Risk was a
Slight Risk stretching from Park Falls, to Duluth, to Bigfork and
Birchdale. The main question at this point is timing and expected
threats from the severe weather. A thorough analysis of the CAMs
showed several possible solutions, although overall there was
consensus that a large complex will slide along our southern
counties this afternoon. As a result, we will have the highest
POP`s in that area this afternoon. Meanwhile, the CAMs indicate
that an area of thunderstorms will develop west and north of the
CWA late this afternoon, and will slide southeast across the
Enhanced to Slight Risk areas during that time. Consensus on any
particular solution is much lower, but in terms of mass fields,
the above mentioned are the better opportunities for strong to
severe thunderstorms. Strong heating in the Red River Valley,
along with cooling temperatures aloft, will combine with a pre
frontal trough to cause steep lapse rates, with the potential for
explosive thunderstorm development, as noted by SPC. The storms
should initially be cellular, with large hail, but then transition
to a wind event as it dives southeast across Minnesota and
portions of Wisconsin. Will strongly highlight the risk of severe
thunderstorms in the southwest today and this evening.

More thunderstorms are expected on Saturday, with a Slight Risk
of severe storms across the CWA, mainly during the period of peak
heating. Surface heating and cooler temps aloft should lead to the
potential for organized storms during the afternoon and evening.

Highs will be in the upper 70s to middle 80s today through

.LONG TERM...(Saturday night through Thursday)
Issued at 420 AM CDT Fri Jul 21 2017

The main concerns in the long term include a chance of strong
thunderstorms lingering into Saturday evening and thunderstorm
chances Tuesday through Thursday night.

A compact shortwave trough is forecast over northwest Ontario and
northern Minnesota Saturday evening with mid-level height falls
across much of the Northland. Showers and storms may be ongoing
during the evening hours and are expected to weaken overnight.
Instability on the order of 500 to 1500 J/kg of MUCAPE and 0-6 km
shear of 30 to 45 knots would continue to support storm-scale
organization with large hail and damaging wind gusts possible. The
shortwave trough and associated vort max is expected to slide
southeastward into the central Great Lakes on Sunday keeping only
a slight chance of showers or an isolated thunderstorm in the
picture. Temperatures will trend cooler for the second half of the
weekend with highs in the middle 60s northeast to the middle 70s
in the west.

A low amplitude mid-level ridge will build across the Northern
Plains and the Canadian Prairies Sunday night through Monday night
with surface high pressure moving gradually eastward through the
region. Look for mainly sunny to partly cloudy skies with slowly
moderating temperatures for the start of the work week. Another
shortwave trough will move across the northern Canadian Prairies
Tuesday through Wednesday. Surface low pressure will move eastward
across central Saskatchewan and Manitoba, and into far northwest
Ontario Tuesday evening. A cool front will accompany the surface
low, and will extend southward into the Northern Plains moving
through the Northland on Tuesday. Showers and thunderstorms are
possible along and ahead of the front, especially Tuesday
afternoon and evening.

The cool front will stall out over the Dakotas through the
Midwest. Another ripple in the mid-level flow and convergence in
the baroclinic zone should give rise to thunderstorms Wednesday
afternoon. The storms are expected to move eastward along the
quasi-stationary front and may graze the Northland Wednesday night
and Thursday. Temperatures for the latter portion of the week
will trend near normal with highs in the low 70s to near 80


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1252 PM CDT Fri Jul 21 2017

VFR conditions should continue through the afternoon and evening
hours today before becoming more MVFR/IFR overnight as a mid-level
shortwave advances eastward into the region. In general, the high-
resolution guidance have backed off from scattered chances of
showers and thunderstorms, but a few strong cells currently over
northwest Minnesota/northeast North Dakota may impact the KINL TAF
terminal this afternoon. There`s some uncertainty at this point
if these cells will dive south of KINL, so put in VCTS for this

Chances of showers and storms, with some possibly strong to
severe, could impact all TAF terminals overnight tonight. Strong
wind gusts and large hail are possible in some of the stronger
storms. Confidence is increasing on fog development as well, given
the higher dew point temperatures and light winds. Mainly MVFR
vsby reductions to 3 to 5 SM, with some IFR reductions at KDLH,


DLH  80  59  73  57 /  30  30  30  30
INL  83  60  77  56 /  20  50  50  50
BRD  84  64  82  60 /  50  70  20  10
HYR  85  64  79  58 /  50  70  20  30
ASX  83  59  73  56 /  30  30  30  30


WI...Beach Hazards Statement until 8 PM CDT this evening for WIZ001.

MN...Beach Hazards Statement until 8 PM CDT this evening for MNZ037.



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