645
FXUS63 KLBF 300905
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
405 AM CDT Mon Sep 30 2024

.KEY MESSAGES...

-  Critical fire weather conditions continue today, with a
   combination of very dry air and strong north winds across the
   area this afternoon.

-  Clear skies, light winds, and surface high pressure will
   lead to temperatures falling into the 30s Tuesday morning.
   The threat for widespread frost formation looks to be limited
   by dry air.

-  Near-critical to critical fire weather conditions are
   possible across western Nebraska as winds strengthen from the
   south.

-  Persistent dry, warm, and breezy conditions will lead to
   elevated to near-critical fire concerns nearly each day late
   this week and into the weekend.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 403 AM CDT Mon Sep 30 2024

The primary concern for the short term will revolve around critical
fire weather conditions today and possibly Tuesday. Additional
details regarding the fire weather threat can be found in the fire
weather section included below.

Currently, relative humidity values remain exceptionally low for
overnight hours in late September, with observations of 25 to 50%
across the area. Winds remain breezy from the south, at 10 to
20 miles per hour. A surface cold front continues to quickly
move southeast across northwest South Dakota, stretching from
near Rapid City to near Faith. This front will continue
southward into northwest Nebraska by sunrise, with a quick wind
shift from south to northwest with its passage. The front will
then clear the rest of the area by late this morning, with very
dry air filtering in behind. Even though temperatures will be
cooler today (in the 70s to near 80) amid strengthening cold
advection, dewpoints falling 15-20 degrees will set the stage
for another period of critical relative humidity this afternoon.
Unfortunately, northerly winds will also strengthen this
afternoon, as surface pressure rises increase across the area as
a strong surface high begins to spill into the northern Plains.
Wind gusts of 35 to 45 miles per hour are expected this
afternoon, as a combination of diurnal and mechanical mixing
should achieve ample mixing depth to bring down higher momentum
flow from aloft. This all points to widespread critical fire
weather conditions today, and see no reason to make changes to
the ongoing Red Flag Warnings in effect through this evening.

By tonight, the stout surface high will begin to enter western
Nebraska, with winds quickly weakening after sunset. Surface
pressures rise to above the 90th percentile climo, as the 1030mb
high centers of the Sandhills around sunrise Tuesday morning. The
positioning of the high will lead to a textbook radiational cooling
setup, with clear skies, light winds, and very dry air in place.
Temperatures look to crash into the middle to upper 30s across much
of southwest and north central Nebraska, with low 30s (and
potentially even upper 20s) across the western Sandhills. That being
said, the potential for widespread frost remains low confidence
with RH values only in the 50-60% range Tuesday morning. With
no freeze having been observed yet this year across the area,
will continue to monitor this threat for the potential for
frost/freeze headlines. However, with the threat for anything
more than localized patchy frost unclear, will forego any
headline issuance for now.

The surface high begins to move off to the southeast by early
tomorrow afternoon, with a quick return to southerly flow across
western and north central Nebraska in its wake. As this occurs,
broad surface cyclogenesis begins in earnest along the lee of the
northern Rockies, leaving the area between a surface trough across
eastern WY/CO and the aforementioned surface high. This leads
to a contracting surface pressure gradient, and south winds
strengthen again tomorrow afternoon. Though not quite as strong
as previous days, gusts approaching 20-30 miles per hour are
expected across western Nebraska, where the surface pressure
gradient should be tightest. With very dry air remaining in
place, the threat for another period of critical fire weather
conditions continues to increase. Future fire headlines may be
needed to cover this threat, as the exact areal extent of
critical conditions becomes more clear.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 403 AM CDT Mon Sep 30 2024

The area looks to remain under the influence of broad zonal flow
aloft through much of the long term, leading to additional dry
frontal passages late this week and into the weekend. Dry air will
remain locked in place across the area, with little in the way of
moisture advection indicated by guidance through the end of the
week. As humidity falls to near critical nearly each day, the fire
weather threat will largely driven by winds. Additional bouts of
near-critical to critical fire weather are likely through into
the weekend, and this will continue to be monitored closely for
the need for any fire weather headlines. Of note, guidance has
begun to point towards anomalously warm temperatures Saturday,
which may again coincide with breezy southerly winds and lead to
critical fire conditions. The bottom line, primarily dry, warm,
and breezy winds look to persist for the foreseeable future,
and near daily fire weather threats will continue across much of
western and north central Nebraska.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1213 AM CDT Mon Sep 30 2024

A powerful Pacific cold front moving through MT will reach nwrn
Nebraska before sunrise and swrn Nebraska by mid to late morning.
Winds of 36020G32KT will develop with the passage of the front.
Ahead of the front LLWS from the south will gradually veer and
become westerly with the approach of the front. There are no
other flight concerns overnight, Monday and Monday evening.

&&

.FIRE WEATHER...
Issued at 403 AM CDT Mon Sep 30 2024

Critical fire weather conditions are expected today across all of
western and north central Nebraska. Critical fire weather conditions
may develop yet again across western Nebraska tomorrow afternoon.

For today: A cold front will quickly push through the entire area by
late this morning, with very dry air filtering into the area in its
wake. Though temperatures will be a touch cooler today compared to
yesterday, (70s to low 80s) the much drier air will lead to
widespread humidity values of 12-17% across all of western and
north central Nebraska. This, combined with north winds at 15 to
30 mph gusting as high as 40 mph, will lead to widespread
critical fire conditions this afternoon and evening. Poor
overnight recovery is expected again tonight into Tuesday
morning (45-65%) though winds quickly weaken from the north
after sunset.

For Tuesday: As surface high pressure exits the area Tuesday
morning, south winds will return and strengthen Tuesday
afternoon across western Nebraska. Temperatures in the upper
70s, relative humidity values in the low teens, and south wind
gusts 20 to 30 miles per hour may lead to a period of critical
fire weather conditions again tomorrow afternoon, primarily west
of Highway 83.

For Wednesday: Temperatures soar back into the middle to upper 80s,
leading to very low humidity values of 10-15% across much of western
and north central Nebraska. However, winds look to remain near or
below 20 miles per hour from the northwest at this time.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM CDT /8 PM MDT/ this evening for
NEZ204-206-208.
Red Flag Warning from noon CDT /11 AM MDT/ today to 9 PM CDT
/8 PM MDT/ this evening for NEZ209-210-219.

&&

$$

SHORT TERM...Brown
LONG TERM...Brown
AVIATION...CDC
FIRE WEATHER...Brown