937
FXUS63 KFGF 231933
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
233 PM CDT Sun Jun 23 2024

.KEY MESSAGES...

- Showers and thunderstorms will move into eastern North Dakota,
  especially northeast parts, after midnight tonight. Isolated
  severe storms are possible.

- Monday will see additional severe storm chances for all areas.

- The next storm threat arrives in the Thursday to Friday time
  frame.

&&

.DISCUSSION...
Issued at 233 PM CDT Sun Jun 23 2024

...Synopsis...

The first 700mb shortwave over the Minnesota arrowhead continues
to push to the east. Haven`t seen any precipitation in this FA
from the wave, but there has been fairly extensive cloud cover.
Brief 500mb ridging follows this wave, although overall it looks
much flatter and a little faster than it did several days ago.
There may be some pieces of shortwave energy (and somewhat of a
low level jet) that eject eastward behind this ridge after
midnight and into Monday morning, which may bring scattered
thunderstorms to portions of the Devils Lake region and eastern
North Dakota. There may or may not be a break as this activity
should weaken over this FA by mid to late morning, before
additional storms fire up during the afternoon. The net result
of the flatter/faster ridging is that the warmest 700mb
temperatures on Monday are squashed a little further south and
east. Even so, by 18z Monday to 00Z Tuesday, 700mb temperatures
look to range from +9C along the Canadian border to +15C along
the Dakotas border. Beyond this, the flow turns more northwest,
with the next substantial wave sometime in the Thursday to
Friday time period.

...After midnight tonight...
The various CAM solutions seem to agree on scattered storms
developing over southern Saskatchewan or western North Dakota
after midnight tonight, with them moving into the Devils Lake
region or portions of eastern North Dakota toward sunrise
Monday morning. The Day 1 SPC Convective Outlook highlights a
slight risk (level 2 of 5) for far northwest North Dakota,
tapering to a marginal risk (level 1 of 5) for the Devils Lake
region. The HREF shows the stronger UH tracks during this period
extending from northwest North Dakota toward the western
fringes of this FA and weakening toward morning. So will keep
the idea of weakening storms and a good amount of cloud cover
moving into at least areas north of the Interstate 94 corridor
in North Dakota and the highway 10 corridor in Minnesota
tonight.

...Monday...
There is not a lot of confidence in what may happen on Monday,
but to start with, what happens late tonight and lingers into
Monday morning will have a big effect. Looking at the various
CAMs, etc., feel there could be several different potential
solutions. One, the convection moving into the Devils Lake
region and portions of eastern North Dakota weakens and there is
a break until more convection develops in the afternoon. Two,
there is no break, and convection continues throughout the
entire day across the entire FA (several CAMs show long duration
UH track across the central and northern FA even during the
late morning through the afternoon. Third, although most CAMs
show a better chance for afternoon convection in the eastern
FA, a few show some development back along the cold front, which
may lag back in eastern North Dakota by 00z Tuesday (which
could be part of the reason the slight risk area was expanded
westward today). Fourth, the development which occurs back along
the cold front quickly becomes severe and turns into a bowing
MCS, producing damaging wind gusts as it progresses across west
central Minnesota along the highway 10 corridor in late
afternoon and early evening hours. Five, much of the capping
holds, and only minimal convection occurs. Overall, there is a
lot of uncertainty.

...Thursday to Friday...
The general 500mb flow pattern should turn more to northwest
flow aloft, with the next decent wave showing up somewhere in
the Thursday to Friday time frame. Overall there is a lot of
uncertainty on the timing and strength of the wave, so don`t
want to put a lot of time into trying to determine what may
occur. Stay tuned.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1214 PM CDT Sun Jun 23 2024

More clouds have developed then anticipated late this morning.
Therefore, the new set of TAFs show BKN clouds at KDVL, KGFK,
KTVF and KBJI through this afternoon, with VFR to MVFR ceilings.
BKN will transition to SCT from west to east late this
afternoon through this evening. Overnight, thunderstorms will
move in from central North Dakota. High level cirrus will
overspread the region from west to east after midnight, with
thunderstorms starting at KDVL around 9z, progressing east to
KGFK a few hours later. There is uncertainty in how widespread
these storms will be and how long they linger in the morning.
There is also a brief chance at some fog tonight if clouds can
clear out long enough. There was not enough confidence to add
fog to any of the TAF sites, and any fog that develops should
be of short duration.

&&

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

&&

$$

DISCUSSION...Godon
AVIATION...Rafferty