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000
FXUS63 KFGF 131739
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1239 PM CDT Sat Apr 13 2024

.KEY MESSAGES...

- An active pattern early to mid next week, with a 60% chance
  for areas to see over an inch in a three day period.

&&

.UPDATE...
Issued at 1239 PM CDT Sat Apr 13 2024

beginning to see second round of showers (more virga than
anything) develop north of HWY 2 as 500-700mb RH increases in
advance of weak mid level wave with cold air advection in the
850-500 layer leading to weak fgen. A deepening BL to 10-12k ft
is contributing to significant low level dryness that is
preventing many of these showers from reaching the ground but
left 20 pops in forecast just in case something manages to reach
the ground. Overall RH seems to be somewhat under performing
compared to the potential and thus fire weather concerns are
lessening as the day progresses. RH as low as 25% and winds up
to the high teens in northeast North Dakota would be the main
area of concern if any this afternoon.

&&

.DISCUSSION...
Issued at 351 AM CDT Sat Apr 13 2024

Deep westerly flow aloft is in place across the Northern Plains,
with surface lee troughing east of the Rockies has help southerly BL
flow develop. There are a series of mid level impulses resulting in
elevated light showers/sprinkles with deep/dry mixed layers limiting
measurable precipitation today. Warm temperatures are expected the
next two days, with some questions about "how" warm related to
lingering mid level cloud cover today (less cloud cover Sunday). 60s
and 70s are likely, with a 25% chance to reach 80F this afternoon in
the southern Red River Valley. A large scale mid/upper low is in
place off the Northern California coast and will be the primary
driver for our pattern shift late Sunday night through next week.

The large scale upper low slowly progresses through the Central
Rockies with southwest flow building into the plains and periods of
showers and embedded/isolated-scattered elevated thunderstorms are
expected to begin to move through eastern ND and into northwest MN
late Sunday night through mid week. THe most organized period of
rain appears to be when the upper low to the south interacts with a
secondary upper low passing to the north and an inverted trough
feature and deformation zone build into our region. All guidance
shows wetting rain, but the higher totals will be tied to where
those features develop and where embedded thunderstorms track. While
there is a general consensus on the large scale pattern the
interaction and eventual track of deformation/trough features still
vary. The stronger northern wave clusters increases probs for 1"+
farther north vs a weaker northern wave that shifts those higher
probs to our southern CWA. The general trends from 24hr haven`t
changed with a 72hr/3 day probability for 1"+ around 60%. Rates
should be drawn out long enough to limit excessive runoff
issues.

Regarding strong/severe potential: CSU GEFS based machine learning
highlights some potential in our area (mainly Tuesday), however
other statistical based datasets CIPS/NBM CWASP probs show the
severe threat remaining south. Soundings as presented at this range
show elevated/narrow CAPE profiles with MU CAPE topping off in the
1000-1300 J/KG range while effective shear is less than 30kt, which
would not raise concerns for severe potential at this time. This
instability would more likely play into locally higher rainfall
rates.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1239 PM CDT Sat Apr 13 2024

Minimal aviation concerns in the taf period with some light
showers possible across DVL, GFK, TVF, and BJI this afternoon
though with high bases over 10000 ft and extremely mixed low
levels it is unlikely this will reach the ground resulting in
virga across these areas until from 18-00Z. Could see some
briefly gusty winds this afternoon in DVL from 22-01Z as winds
shift to the NW with no threat of gusts at remaining sites
through the period. Winds transition to NW at all sites by 00Z.

&&

.FIRE WEATHER...
Issued at 351 AM CDT Sat Apr 13 2024

Regarding Fire Weather Today-Sunday: Surface troughing shifts east
and the reduction in surface gradient/winds aloft during peak
heating should limit wind gust potential for "most" areas, though
there is still a low potential for occasional gusts 15-20 mph in
the early afternoon in MN. Adjustments to Td`s were made to better
reflect deep mixed layers (based on previous days) and afternoon RH
values are forecast to fall to the 21-27% range across eastern
ND/northwest MN, with the lowest values tied to where the warmest
temperatures are (70s to near 80) along/west of the Red River Valley.
There is a window for near critical fire weather conditions as
northwest winds increase behind the surface trough in the Devils Lake
Basin and peak mixed layer winds in the 20-25 mph range may result
in a 1-2hr window for low RH/gusty wind crossover in the late
afternoon. Gusts though may be less frequent and if mid level clouds
linger we may not mix as deep lowering confidence. For now we
are monitoring trends and holding off on messaging at this time.

&&

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

&&

$$

UPDATE...TT
DISCUSSION...DJR
AVIATION...TT
FIRE WEATHER...DJR