672
FXUS63 KFGF 020804
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
304 AM CDT Sun Jun 2 2024

.KEY MESSAGES...

- There is a level 2 out of 5 risk for severe storms this
  afternoon and evening for the entire FA. Hazards include hail
  up to golf ball size, wind gusts up to 60 mph, and a few
  tornadoes possible.

- Widespread showers and thunderstorms are expected late Monday
  night into Tuesday. Severe storms are unlikely.

&&

.DISCUSSION...
Issued at 304 AM CDT Sun Jun 2 2024

...Synopsis...
As the CAMs were starting to show at this time yesterday,
scattered showers have begun to show up along the Interstate 94
corridor early this morning. There haven`t been any lightning
strikes yet, but the HREF 1-hour thunder probability does show
this potential developing in the next hour or two. This is
elevated convection, tied more so to 700mb warm advection and a
developing 25-35 knot low level jet. These parameters lift
northward, so by sunrise into mid Sunday morning most of this
activity should lift into the highway 2 corridor and northward.
After seeing this consistency from yesterday, have pretty good
confidence with it. However, this will have implications on
heating and instability for later, as the clouds and any
precipitation will hold down the temperature rise along and
north of highway 2 today. The NBM has caught on to this with
cooler highs in these areas today.

...Severe potential this afternoon and evening...
After having pretty good confidence on how convection may occur
early this morning, the confidence for how things may unfold
this afternoon is much lower. So why is that? First, the surface
features look very weak today, versus what was there at this
time yesterday (a surface low near Jamestown at 00z Monday with
a trailing cold front, and a warm front extending eastward along
Interstate 94). As of now, not sure there will be much of any
surface low or boundaries, or it will just be a weak trough.
Surface winds do look pretty gusty from the south today, but
behind the so called cold front/trough they are pretty light. So
there is no strong push behind this weak boundary in the 21z
Sunday to 03z Monday period. Second, as mentioned in the
synopsis section, morning clouds and precipitation will likely
limit the convective potential across the north. CAMs yesterday
had showed a nice line of storms forming over central North
Dakota 21z Sunday-00z Monday, then moving into eastern North
Dakota and weakening during the evening.

CAMs now show an earlier and more southern track to the best
severe potential this afternoon and evening. And again, this
could change. To start, SPC kept the entire FA in a slight risk
for severe weather. Some of the main parameters remain the
same, starting with good moisture return. However, SPC did note
that surface dewpoints by afternoon in the 60s might be a
little too optimistic. The upper support is not ideal, but
enough. The HREF is indicating maybe 1500-2000J/kg of MLCAPE
across southeast North Dakota by 21-23Z Sunday, with about 35
knots of 0-6km effective shear. The better mid level lapse rates
hold along the Dakotas border down into eastern South Dakota.
Meanwhile, the low level jet cranks up pretty good from 21z
Sunday to 00z Monday (around 50 knots), so much stronger than it
is right now. However, its best focus may be into Minnesota
lifting into southern Canada in the evening. CAMs seem to be
latching on to one cluster of storms across northwest Minnesota
during the late afternoon and early evening, feeding off the low
level jet, while another cluster tries to get going from
Jamestown to Oakes. As the storms from Jamestown to Oakes push
east during the late afternoon and early evening, they turn
linear and sag southeastward toward the better CAPE. These would
be more wind producers. The HREF shows the best UH tracks
developing around Barnes County about 22z Sunday, and continuing
across southeast North Dakota and adjacent areas of west
central Minnesota until about 03z Monday. Will maintain the
inherited hazard wording for hail (although will go golfball
size to match Bismarck, wind (60 mph), and a few tornadoes
possible, although it may be trending more toward wind and maybe
hail.

...Next event Monday night into Tuesday...
The next good shortwave is still on track to move through the FA
Monday night into Tuesday. This is a little faster than what was
seen yesterday, so that most of the precipitation moves through
during non-peak heating hours. This means there is not very much
CAPE to work with. The track of the wave may favor the northern
half of the FA with slightly heavier precipitation amounts now.
Quarter inch amounts look pretty favorable for all areas,
ranging from a 90 percent probability along the Canadian border
to 60 percent along the Dakotas border. Probs for amounts
greater than 1 inch range from 40 percent along the Canadian
border to 10 percent along the Dakotas border. Uncertainty then
comes into play for the later periods, with the potential for
an upper low to linger over the Northern Plains for a few days,
or slowly shift east.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1147 PM CDT Sat Jun 1 2024

VFR conditions prevail through much of the TAF period, with the
primary concern being the formation of showers and thunderstorms
heading into Sunday. Light and variable winds overnight are
expected increase out of the south after sunrise Sunday morning. A
weak shortwave will bring slight chances for mainly isolated
storms across the area early Sunday morning, with little
confidence in location based on upstream observations. Much
higher probabilities for impactful thunderstorm development
enter the forecast Sunday afternoon and evening, with strong to
scattered severe thunderstorms possible.

&&

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

&&

$$

DISCUSSION...Godon
AVIATION...Lynch