Special Weather Statement, NWS Grand Forks, ND

Area Forecast Discussion
National Weather Service Grand Forks ND
1249 PM CDT Thu Jul 18 2019

.UPDATE...
Issued at 1243 PM CDT Thu Jul 18 2019

Sky cover lingering longer across southern valley may complicate
timing of initiation. Very light returns on radar associated with
possible virga (can't rule out sprinkles with that). Still not a
lot of confidence on coverage for thunderstorms this
afternoon/evening, but there is a clearing trend in some areas
could could help destabilization. Westerly winds beginning to
shift and increase in our western CWA could start to enhance
convergence near trough axis in the RRV, so just need to get some
better clearing in our south where higher Tds are in place.

UPDATE Issued at 1006 AM CDT Thu Jul 18 2019

Showers/embedded weak thunderstorms still progressing through Lake
of the Woods/Roseau areas with a few light showers further east
along International Border and upstream of Jamestown struggling
to hold together as the move towards our CWA. Best synoptic
forcing is still in Canada with smaller scale features responsible
for current activity (which is expected to end by midday).

CAMs still showing potential for isolated thunderstorm
development along convergence zone advertised to extend from far
northwest MN into southeast ND. Tds in the mid to upper 60s are in
place in the areas, however west-southwest BL flow is bringing
slightly lower Tds eastward. Assuming we have enough clearing
from morning cloud cover, low level lapse rates and instability
should increase. Mid level lapse rates are unimpressive which
favors diurnally driven activity. Deep shear is good through this
evening, but this is a conditional severe threat. We need to
destabilize and weaken ML CINh, and convergence needs to be deep
enough to aid in initiation.

UPDATE Issued at 644 AM CDT Thu Jul 18 2019

There has been a relatively nice bowing type element associated
with the wave moving through the central FA. However, the
structure was not quite there for really strong winds at the
surface. Did see some 30 to 40 mph winds associated with it from
Cooperstown to Mayville to south of Crookston. It is currently
headed toward Fosston and Bemidji. Once this moves through, that
may be it for precipitation until potentially the afternoon again.

&&

.SHORT TERM...(Today and tonight)
Issued at 401 AM CDT Thu Jul 18 2019

Currently have three distinct areas of showers and thunderstorms
lined up across southern North Dakota, one over the southern Red
River Valley, another moving into the Valley City to Litchville
corridor, and another south of Bismarck. Otherwise there is a lone
area north of Cando. Not expecting any of this activity to be
severe, but winds could be close across western Barnes down toward
Lisbon. The Jamestown airport had a 52 knot wind gust as this line
came through. However, the line itself is moving at about 40 mph
or so and appears to be weakening, so think the Jamestown report
was a dying cell. Other nearby wind gusts have been more in the 40
mph or so range. Not sure how long any of this activity will
linger through sunrise and thereafter. Models are generally not
handling it very well. Think it will mainly affect areas south of
the highway 2 corridor early this morning. Whether it holds
together into mid morning, confidence is pretty low.

There is quite a bit of convective debris cloud cover across the
area, extending all the way back into western North Dakota.
However this should thin by late morning into the afternoon,
allowing decent heating to occur. High temperatures should be a
little warmer than yesterday, with the humidity still in place.
Better heat and humidity will be located over southern Minnesota,
where the low level jet has aided storms there early this morning.
Like yesterday, there is decent effective shear this afternoon,
but weak surface convergence/boundaries. Therefore confidence in
much thunder redevelopment today is low.

All said, the suite of high resolution models differ on potential
outcomes today. However, some of them show a window from mid
afternoon into the early evening for some thunder. Several of
these solutions show better chances for this being across
southeast North Dakota into adjacent areas of west central
Minnesota. HREF 24 hour hail probability actually favors northwest
and north central Minnesota. SREF calibrated severe thunderstorm
products also favor northwest and north central Minnesota. This is
likely the reason the SPC day 1 convective outlook has a
broadbrushed marginal risk over most of the FA today. Think this
risk should be done by mid evening tonight.

.LONG TERM...(Friday through Wednesday)
Issued at 401 AM CDT Thu Jul 18 2019

Models have been showing another weak impulse across the southern
half of the FA on Friday. Forecast has been carrying a low chance
for pcpn in that area, so left as is for now.

Friday night through Saturday night...Mid level instability is
forecast over the far southeast zones and will be moving out of
the forecast area on 00Z Sat. The rest of the area will be quite
stable. Model differences are already showing up this time period
with the ECMWF the faster solution compared to the GFS. THe GFS
drops some precip over the northern zones Sat night with a short
wave trough moving through. The ECMWF was farther east.

Sunday to Wednesday...Upper air pattern amplifies this period.
Zonal flow across the International border will become more
meridional. Upper level ridge will build from NM/AZ area to the
ALTA/SASK area. Short waves can be expected in the northwest flow
aloft but may be farther east. Little or no precip is forecast
after Sun.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1249 PM CDT Thu Jul 18 2019

VFR conditions should prevail through the TAF period across
eastern ND and northwest MN, though periods of CU in the 5-7 KFT
AGL range are expected this afternoon/evening before sunrise.
Thunderstorms can't be ruled out from KFAR to KTVF and east, but
coverage will be low through this evening. Another round of
showers/embedded thunderstorms may move west to east across the
region late tonight into tomorrow with a cold front approaching,
but there is still variance on coverage/timing and I held off on
adding to TAFs.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&

UPDATE...DJR
SHORT TERM...Godon
LONG TERM...Godon/JH
AVIATION...DJR

Hazardous Weather Outlook
National Weather Service Grand Forks ND
412 AM CDT Thu Jul 18 2019

NDZ006-007-014-015-024-190915-
Towner-Cavalier-Benson-Ramsey-Eddy-
412 AM CDT Thu Jul 18 2019

This hazardous weather outlook is for portions of eastern North
Dakota.

.DAY ONE...Today and Tonight

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

MNZ001>009-013>017-022>024-027>032-040-NDZ008-016-026>030-038-039-
049-052>054-190915-
West Polk-Norman-Clay-Kittson-Roseau-Lake Of The Woods-
West Marshall-East Marshall-North Beltrami-Pennington-Red Lake-
East Polk-North Clearwater-South Beltrami-Mahnomen-
South Clearwater-Hubbard-West Becker-East Becker-Wilkin-
West Otter Tail-East Otter Tail-Wadena-Grant-Pembina-
Eastern Walsh County-Nelson-Grand Forks-Griggs-Steele-Traill-
Barnes-Cass-Ransom-Sargent-Richland-Western Walsh County-
412 AM CDT Thu Jul 18 2019

This hazardous weather outlook is for portions of eastern North
Dakota, west central and northwest Minnesota.

.DAY ONE...Today and Tonight

Scattered severe thunderstorms are possible from 2 pm to 8 pm
today. The main hazards will be quarter sized hail and 60 mph
wind gusts. Isolated tornadoes are also possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed today.

Special Weather Statement
National Weather Service Grand Forks ND
321 PM CDT Thu Jul 18 2019

MNZ006-182045-
Lake Of The Woods MN-
321 PM CDT Thu Jul 18 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN LAKE OF THE WOODS
COUNTY UNTIL 345 PM CDT...

At 321 PM CDT, Doppler radar was tracking a strong thunderstorm near
Angle Inlet moving east at 35 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

This strong thunderstorm will be near...
  Penasse around 330 PM CDT.
  Oak Island, Garden Island State Recreation Area and Flag Island
  around 335 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If on or near Lake of the Woods, get out of the water and move
indoors or inside a vehicle. Remember, lightning can strike out to
10 miles from the parent thunderstorm. If you can hear thunder, you
are close enough to be struck by lightning. Move to safe shelter
now! Do not be caught on the water in a thunderstorm.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 4937 9513 4935 9507 4936 9501 4937 9499
      4937 9495 4933 9486 4932 9481 4929 9482
      4914 9478 4915 9515 4938 9515
TIME...MOT...LOC 2021Z 266DEG 32KT 4925 9505

CJ