997
FXUS63 KFGF 092102
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
402 PM CDT Sun Mar 9 2025

.KEY MESSAGES...

- Windy conditions are expected Monday, with gusts to 60 mph
  along and west of the Red River Valley Monday afternoon and
  evening.

- The combination of windy conditions and low RH values will
  result in critical fire weather conditions Monday afternoon,
  with a 50% chance for critical fire weather conditions across
  west central Minnesota.

- A strong storm system will move across the U.S. late next
  week. A range of scenarios exist regarding impacts across the
  Northern Plains, with a 30% chance for moderate impacts across
  our region.

&&

.DISCUSSION...
Issued at 400 PM CDT Sun Mar 9 2025

...Synopsis...

Northwest flow with rising heights as strong ridging builds over the
southwest US is in place this afternoon, and this eventually
flattens Monday in response to an approaching shortwave out of
Canada, which brings rain, snow, and sleet chances to northern
locations as a cold front moves through the region. Near record
temperatures are forecast for Monday as deep westerly downslope flow
and compressional warning occurs ahead of the front. Behind the
front cooler (still above average) temperatures arrive Tuesday
before temperatures warm again ahead of the approaching system
Friday into the weekend.

...High Wind Monday...

Deep unidirectional westerly flow develops with mixed layer winds in
the 30 to 45kt range along and west of the Red River Valley. EFI
shows values 0.7 to 0.9 (highest values west of our CWA), with 0.9
values matching a signal for potential warning impacts within the
region. Mixing heights especially as the strong cold front arrives
late afternoon and evening become questionable due to the
development of a warm nose/elevated inversion. However, very strong
3hr pressure rises 10-14MB (NAM/GFS) and strong 925MB CAA exceeding
-100C/12hr and even extending to 850MB immediately behind the cold
front matches a conceptual model for efficient downward motion
which could help mixing 50kt+ winds to the surface, only over a
shorter (1-3hr) duration immediately as the front passes.
Considering the consistency of this signal an upgrade decision was
made, with messaging highlighting the period of strongest gusts
being associated with that frontal passage.

...Winter Storm Potential Late Week...

A strong Colorado-low type pattern is still forecast to develop into
the Northern Plains, with consensus between ensemble clusters
increasing on the general track/timing of the low pressure system.
NAEFS shows a mean 980MB surface low centered over southern MN, with
ensemble clusters aligning the inverted 700MB trough axis and
deformation within our CWA (though varying in smaller degrees on
strength and position which can make large differences on impacts).
Deep/strong moisture advection and strong ascent will support
moderate to heavy precipitation, and NBM probs show a 30% chance for
greater than 1" liquid equivalent precipitation within our area
(mainly south and east).

Any shift or change in strength of the system can also shift the
timing of temperatures at the surface or aloft, changing p-type, and
any ice or snow accumulation, and the location/timing of those
impacts. Very strong winds are likley even at this range, and where
all snow occurs falling snow combined with winds could result in
Blizzard conditions. As may be expected with a system featuring such
strong WAA and a likely TROWAL development there is a chance for
icing and probabilities for 0.1" are in the 10-20% range. Due to the
amount of warm air being wrapped into this system potentially
delaying rain to snow change over probabilities for 6"+ from snow
accumulation are 20-30%. pWSSI shows a 20-30% chance for moderate
(lower end warning) impacts and a 5% probability for major (danger to
impossible) winter impacts Friday night through Saturday night over
our region.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1244 PM CDT Sun Mar 9 2025

VFR conditions are expected across eastern ND and northwest MN
through the TAF period, with dry westerly flow in place. Winds
12-15kt this afternoon shift to the southwest and drop below
10kt at sunset before gradually increasing from the west again
after sunrise Monday morning. The strongest winds arrive after
this TAF period in ND and parts of northwest MN Monday.

&&

.FIRE WEATHER...
Issued at 400 PM CDT Sun Mar 9 2025

Mixing (of lower Tds and higher winds) combined with very warm (near
record) afternoon temperatures, are expected to result in 20-25% RH
values across southeast ND. Considering the dry nature of finer/one
hour fuels the Red Flag Warning was upgraded previously and continues
for Monday afternoon. There are still questions about how
warm/dry conditions will be in west central MN, however RH
values should be at least near Red Flag Criteria. Considering
the magnitude of winds and the west to sudden northerly shift in
winds with the frontal passage critical fire weather conditions
are still a concern four our southeastern fire zones in MN.
Considering how close we are to RFW and a few degrees in temps
or lower Tds I felt the winds/frontal passage justified the
issuance of a Fire Weather Watch.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...High Wind Warning from noon to 10 PM CDT Monday for NDZ006>008-
     014>016-024-026>030-038-039-049-052>054.
     Red Flag Warning from 11 AM to 7 PM CDT Monday for NDZ028>030-
     038-039-049-052-053.
MN...High Wind Warning from noon to 10 PM CDT Monday for MNZ001>004-
     007-029.
     Fire Weather Watch from Monday morning through Monday evening
     for MNZ003-024-027>032-040.

&&

$$

DISCUSSION...DJR
AVIATION...DJR
FIRE WEATHER...DJR