752
FXUS63 KFGF 241801
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
101 PM CDT Fri May 24 2024

.KEY MESSAGES...

- Will keep monitoring impacts of rain from Thursday and
  additional rain today for rises on area rivers.

- Temperatures today in Cando-Langdon areas from model data seem
  hard to believe as HRRR drops them into the mid 30s midday and
  aftn. Kept hourly temps a tad warmer upper 30s and rain in the
  fcst.

- Low temps below 36F possible in northeast ND late
  tonight/early Saturday. Confidence not yet high enough to
  issue any frost headlines.

&&

.UPDATE...
Issued at 101 PM CDT Fri May 24 2024

Upper low continues to rotate into southeastern ND, and there
has been enough clearing in that area for a few tiny
thunderstorm cells to develop. There is a tiny area of non-
supercell tornado potential on the SPC meso page just west of
our CWA, and give the position of the upper low can`t rule out
something strange developing. Will message the potential for
some funnels in southeastern ND with an SPS, and continue to
monitor for anything stronger.

On the other side of the system, there has been some snow
accumulations just outside our CWA, and there has been a few
flakes and a light dusting reported in northern Towner county.
Bumped up snow mention in our northwestern counties for now, but
at this point think impacts to travel are minor to non-
existent.

UPDATE
Issued at 1003 AM CDT Fri May 24 2024

Rain continues to rotate around the upper low, with the dry slot
starting to move into our far southwestern counties. The
precipitation forecast seems on track and only minor tweaks
needed. Winds at Detroit Lakes gusted up to 55 mph around 915
AM, but came back down and have been the only spot in our area
near wind advisory criteria. Winds in that area should come down
as the center of the surface low approaches in the next few
hours. At this point, think the best chances for wind advisory
winds will be in southeastern ND later on this afternoon on the
backside of the low where they will have the extra push of
height rises and cold air advection. However, still borderline
and will hold off on any headlines for the moment and see how
winds develop as we head into the afternoon.

UPDATE
Issued at 721 AM CDT Fri May 24 2024

Forecast going as anticipated. Upper low in far north central SD
at 12z with sfc low between Aberdeen and Bismarck. Both lows
will track northeast today and be near Pembina ND region by late
in the day. On the southeast and east side of upper low as
surface boundary moves around the low, will need to monitor for
funnels or if increased instability low topped supercell
hazards. This would be I think timing wise more in the mid RRV
and parts of MN ESE from GFK to Mahnomen region.

&&

.DISCUSSION...
Issued at 340 AM CDT Fri May 24 2024

Upper low in northwest South Dakota with surface low east of
Hettinger ND at 08z. The upper low and sfc low will move
northeast today and be just west of Grand Forks at 18z and be
near Pembina ND at 00z. The initial area of rain and
thunderstorms has moved thru most of the the Red River valley
and now into south central Manitoba. Deformation rain band is
from SW Manitoba thru the Turtle Mountains, Minot to Dickinson
area into parts of western SD. Looking to our south another
surge of showers and a few t-storms is moving north-northeast
thru SW Minnesota and far eastern South Dakota. This area of
moisture will spread into the Red River valley and thru NW/WC MN
during the course of the day as rain wraps back around the
system into central ND.

A few things to consider today.

Track of upper low just west of GFK and surface low near GFK
early to mid afternoon will put the mid RRV in a favored spot
for potential low topped thunderstorms, Canadian GEM has about
500 mb MU CAPE into the Grand Forks area early this afternoon,
with GFS and other short term models a bit weaker more like
100-200 j/kg. Unless some sunny breaks occur and allow temps to
warm just east of the upper low early this aftn, unsure if
enough instability will be realized for low topped supercells.
May be more showers, weak t-storms. But with upper level low and
sfc low nearby and potentially a weak cold front swinging north
around the low, some sfc vorticity. This pattern does look like
prev patterns when funnels have occurred. Uncertainty is too
high to message this in social media, but worth mentioning in
this forecast discussion. I would peg the chance for conditions
favorable for funnels to be 40 pct.

Winds on the backside of the system will br near advisory
levels, with strongest mixing south central ND into central SD.
Though a period of potential wind gusts near 45 kts is possible
into SW fcst area 21z-00z period today. Coord with ABR and BIS
and for SE ND will not issue a wind adv at this time since
stronger wind potential is not til late today and the situation
can be evaluated further during the dayshift.

What has me scratching my head the most is model insistence that
temps will drop into the mid 30s in north central ND and parts
of Devils Lake/Langdon areas this aftn with rain mixing or even
changing to snow some models suggest. I have a tough time with
this degree of cooling as there is no source of that cold of an
airmass anywhere close and dew pt/temp differences are already
at 0-1C so not like there is evaporation cooling involved. HRRR
temps would be the coldest. NBM temps used in fcst would have
upper 30s and rain in that area. Something to monitor for sure.
If any place would get wet snow later today it would be higher
terrain of the Turtle Mountains. But also I always recall many
times the Langdon surprise as it cools there more than anywhere
else it seems.

Tonight....how cold will it get. There is no big high moving in
and potential for scattered clouds at least and some wind. NBM
lows showing 31 in Towner county seem too aggressive, so kept
coldest temp at 32 in NW fcst area. Frost tool gives no frost
due to cloud/wind potential. My confidence in lows below 35 in
Devils Lake-Langdon area is about 50 percent and for lows to 32F
about 20 percent. Just not enough confidence yet to issue any
frost advisory for areas with low temps below 36F at this time.
BIS agreed.

Saturday into Monday will feature a broad 500 mb east-west
trough over the area. Some weak embedded short waves with enough
sfc heating in the aftn to generate a few hundred CAPE and a
chance for a few showers each day.

Tues-Wed should see an upper ridge build in temporarily and
temps warm some, before a possible next 500 mb wave moves in
late next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 101 PM CDT Fri May 24 2024

Rain and showers continue to lift northeastward across the
forecast area. Ceilings are VFR at the Red River TAF sites, but
some MVFR ceilings and vis continue to hang out at KDVL and the
MN airports. Some low level wind shear at KBJI also with strong
low level jet. Showers and MVFR ceilings will impact most of the
TAF sites through the afternoon and evening, and some IFR is
possible towards morning. Winds will be shifting around to the
southwest, then west and northwest at some sites as low
pressure shifts off to the east. Gusts up around 30 kts will be
possible. Some decrease in winds and improvement in conditions
possible at the end of the period.

&&

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

&&

$$

UPDATE...Riddle/JR
DISCUSSION...Riddle
AVIATION...JR