964
FXUS63 KFGF 182011
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
311 PM CDT Wed Sep 18 2024

.KEY MESSAGES...

- There is a level 1 out of 5 risk for severe storms for most of
  the forecast area this afternoon and evening, and a level 2
  out of 5 risk for far southern portions of the Red River
  Valley and west central Minnesota. Some storms could produce
  hail up to ping pong balls and winds to 60 mph, along with
  tornadoes.

&&

.DISCUSSION...
Issued at 310 PM CDT Wed Sep 18 2024

...Synopsis...

Strong, wrapped up upper low continues near the MT/ND border,
with the center of the surface low still well stacked and out
west. The upper system will push off into Canada tonight, with
the trailing surface boundary moving into the Red River Valley.
Some wrap around into Thursday as the upper system continues to
lift northeast, but then flow transitions more towards a more
split pattern with the northern branch bringing some weak waves
by our CWA. A few of the deterministic models bring the southern
branch cut off into MN near our counties. However, there is not
a lot of ensemble agreement on this solution and there does not
seem to be much of a wet signal in the R or M climate. Temps do
seem like they will be trending more towards seasonal averages
up until Wednesday when ridging builds back in.

...Severe potential this afternoon and tonight...

Clouds and shower activity continue to slowly diminish across
our forecast area. SPC mesoanalysis has 1000-1500 J/kg of ML
CAPE across eastern ND and effective bulk shear of 35 to 40 kts.
There has not been much in the way of forcing, but there is a
boundary/dryline and one of the vort lobes currently over
western ND could skirt our CWA. Can`t completely rule out
severe thunderstorm development, but given weak forcing the
marginal/small slight risk continues to seem reasonable. If
anything does fire, supercells will be possible, with the
possibility of a tornado, along with ping pong ball sized hail
and 60 mph winds. Several of the CAMs runs are not very
impressive with storm development this evening, but do break out
some elevated activity later tonight along the boundary as it
moves through western MN thanks to the low level jet. SSCRAM
guidance isn`t too bullish on severe impacts and HREF just has
a few updraft helicity paintballs above 75 m2/s2. Will continue
to monitor how things evolve this evening.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1244 PM CDT Wed Sep 18 2024

Currently VFR at most of the TAF sites with scattered rain
showers. Some intensification to thunderstorms is possible at
least at a few of the TAF sites, so kept the tempo groups with
thunder in them for now. Mostly VFR conditions but heavier rain
and sometimes ceilings around 3000 ft could bring conditions
down to MVFR for a brief period. Winds from the southeast will
continue, with some low level wind shear at a few airports later
tonight. Winds will shift to the southwest by the end of the
period with some gusts over 20 kts as surface low pressure lifts
up into Canada.

&&

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

&&

$$

DISCUSSION...JR
AVIATION...JR