Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 192357 AAA
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
657 PM CDT TUE JUL 19 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 306 PM CDT Tue Jul 19 2016

Short term focus on convection overnight associated with a short
wave riding over the upper level ridge on the nose of the 850hPa
warm air advection. Currently monitoring a few rambunctious
supercells tracking out of southeast Manitoba into NW minnesota.
These storms are expected to translate along the international
border and move into the Iron Range region around midnight,
tracking over the Minnesota Arrowhead through daybreak. Meanwhile
another wave will bring convection to central MN
overnight...moving into northern Wisconsin during the early
morning hours. A few strong to severe storms will be possible
overnight along the international border...with a threat for
large hail, damaging winds and breif heavy downpours.

Overnight lows will remain well above normal in the mid 60s to
around 70 as a SW 20-30kt low level jet allow for 850hPa
temperatures to warm to around 20C by daybreak. The hot and muggy
conditions will persist Wednesday as temperatures warm into the
upper 80s to low 90s with widespread heat index values of 90 to
105 degrees. A light onshore breeze along the north shore and at
the head of lake superior will keep conditions cooler by the lake,
with afternoon highs in the 70s to low 80s.

An excessive heat watch remains in effect for the prolonged
period of HOT AND HUMID conditions. Although the heat will not
persist as long into the week for the Iron Range
zones...anticipate a heat advisory will be needed for a portion of
north central MInnesota tomorrow as heat index values will
approach the 100 degree mark during the afternoon and evening
hours.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 306 PM CDT Tue Jul 19 2016

The main concerns with this forecast package continue to be the
dangerously warm temperatures Thursday and periodic thunderstorm
chances through early next week.

Significant dome of high pressure aloft will remain over the Central
and Southern Plains at the start of the period with broad ridge
extending north across the northern tier states and southern
Canadian Prairies. A shortwave trough is forecast to be located over
southern Saskatchewan by 00Z Thursday and will advance eastward
across the region Wednesday night and Thursday. Showers and
thunderstorms may be ongoing over southern Saskatchewan at the start
of the period, or are expected to develop, and track along the
International Border into northern Minnesota by mid-morning
Thursday. There is a potential for heavy rainfall with these storms,
along with large hail, and damaging wind gusts. At this time, it
seems the placement of the heaviest rainfall will preclude much of a
flooding threat (being well north of the areas affected by heavy
rain last week). Still, this setup bears watching with later
updates. Conditions will be hot and muggy over much of my forecast
area. Whether the northern tiers of zones reach advisory or warning
criteria will depend on the storm track, and will be easier to
refine tomorrow night. Areas along and south of US Highway 2, in
Minnesota and Wisconsin, will be at the highest risk for dangerous
heat conditions. Continue to highlight these areas with an Excessive
Heat Watch.

Quasi-zonal flow develops behind the departing shortwave Thursday
evening, with several shortwaves and areas of DCVA noted upstream
across the northern Plains and Rockies. Additional thunderstorm
chances will evolve late Thursday night, but more likely by Friday
afternoon, as shortwave is progged to dig southeastward into the
area. In any case, the pattern change will result in cooler
temperatures and lower dewpoints finding their way into the
Northland. Cooler and more comfortable conditions are expected for
the end of the work week.

A more robust shortwave trough is forecast to move into the
Northland on Saturday. Timing and intensity of this feature is
split between the deterministic guidance with the GFS a bit faster
and the GEM the slowest. ECMWF splits the two, but leans a bit
closer to the GEM solution. In either case, the timing of this
feature will figure substantively to the severe weather potential.
Storms seem to be a foregone conclusion for the Saturday/Saturday
night period, but details will remain fuzzy until timing and
strength of the shortwave becomes a bit more coherent. In any case,
anyone with interests outdoors this weekend are encouraged to pay
special attention to the forecast. The potential for severe weather
will exist somewhere in the Northern Plains into the Upper Midwest,
but the exact location and timing of the threat are uncertain at
this time.

All of the deterministic guidance features rising heights as a ridge
builds behind the departing shortwave late in the weekend/early next
week. This evolution would support a period of quieter conditions
once again.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 653 PM CDT Tue Jul 19 2016

VFR conditions will prevail at least through 06z. There will be
increasing chances for thunderstorms after 06z. Increasing
moisture may result in early morning stratus and fog at mvfr or
ifr levels that will improve after 15z. Look for a chance of
scattered storms in the morning and perhaps again in the late
afternoon or after 00Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  64  86  70  87 /  30  30  30  40
INL  68  91  69  90 /  50  20  50  30
BRD  71  90  73  92 /  30  10  10  20
HYR  67  88  72  91 /  50  50  20  30
ASX  65  88  71  86 /  40  50  40  40

&&

.DLH Watches/Warnings/Advisories...
WI...Excessive Heat Watch from Thursday morning through Thursday
     evening for WIZ001>004-006>009.

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

LS...None.
&&

$$

SHORT TERM...Graning
AVIATION...CLC
Long term...Huyck


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