057
FXUS63 KOAX 052314
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
614 PM CDT Sat Oct 5 2024

.KEY MESSAGES...

- Extreme fire danger (see Fire Weather section of AFD) will
  continue through 8 PM CDT across eastern Nebraska and
  southwest Iowa.

- A cold front will move through the region this afternoon and
  evening, bringing highs in the upper 60s and low 70s for
  tomorrow and Monday.

- Warm, mild and dry conditions are expected next week into next
  weekend with highs gradually warming into the mid and upper
  80s.

&&

.DISCUSSION...
Issued at 213 PM CDT Sat Oct 5 2024

     Today and Tonight...

Extreme fire danger conditions are currently in place across
much of eastern Nebraska and western Iowa. Details on this can
be found below in the Fire Weather section of the AFD.

A cold front currently extends from Grand Island northeast to
Sioux City. This front will continue to push southeast across
our area bringing a cooler and very dry airmass in from the
northwest. Ahead of this front however, very efficient mixing
and boundary layer growth owing to strong unidirectional
southwesterly flow through the depth of the troposphere has
allowed temperatures across southeast Nebraska to warm into the
mid and upper 90s. Behind the cold front, temperatures will top
out in the low 80s before cooling this evening. There will not
be any precipitation from this cold front.

The very dry air behind the front will allow for efficient
radiative cooling, bringing low temperatures in the 40s tonight.
A few urban locations may have lows closer to 50 degrees. All
in all, temperatures will quickly cool and become chilly tonight
heading into tomorrow.

     Tomorrow through Friday...

A high amplitude longwave ridge will build into and persist over
the central CONUS tomorrow through the end of the forecast
period. This will keep precipitation chances well to the north,
skies clear, and afternoon highs in the 80s. This will also be
a very dry airmass with minimum relative humidities each
afternoon likely ranging from 20 to 30 percent. The lack of a
strong surface pressure gradient should keep winds much lower
than they are today and mitigate the fire danger through next
week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 608 PM CDT Sat Oct 5 2024

The cold front has made it past the TAF sites, bringing winds
around to the northwest across the majority of eastern Nebraska
and southwest Iowa. Wind speeds will continue to diminish
through the evening hours, dropping below 12kts by 04Z tonight.
Winds will pick up again, late Sunday morning and afternoon.
However they will not be nearly as gusty as Saturday, remaining
near 12-15 kts.

&&

.FIRE WEATHER...
Issued at 213 PM CDT Sat Oct 5 2024

There continue to be two primary regions of concern for extreme
fire weather danger. The first is across southeast Nebraska and
far southwest Iowa. Multiple fires have already been observed in
this region and each have had a period of rapid growth. Strong
unidirectional southwesterly flow through the depth of the troposphere
has set the stage for efficient boundary layer growth this
afternoon. There are a couple of implications from this. First
is dry and well mixed boundary layers respond quite well to
diurnal heating. Current observations support this with
temperatures in the mid and upper 90s being observed at various
stations across southeast Nebraska. With dew points in the 40s
and low 50s, relative humidities have also dropped as part of
the diurnal cycle. Current relative humidities range from 15 to
25 percent, and may very well drop a few more percentage points
before rebounding after sunset. The other implication from the
rapidly growing boundary layer is strong flow aloft is able to
efficient mix down towards the surface. This has brought
widespread wind gusts of 30 to 40 mph to the area. The
conjunction of strong wind gusts and very low relative
humidities have created an environment with extreme fire danger,
conducive of supporting explosive fire growth for any fires
that are not quickly contained.

A second but still equally dangerous area for fire weather
potential is across much of northeast Nebraska behind the cold
front. Winds behind the front are expected to gust up to 35 mph
out of the northwest. Dew points in this airmass are also very
low, ranging from the low 30s to near 40 degrees. With post-
frontal temperatures in the low 80s this afternoon, relative
humidities will range from 15 to 25 percent. This conjunction of
low relative humidities and strong winds will also set the stage
for an environment characterized by extreme fire danger.

The last complicating piece to the fire weather scenario today
across the region is the wind shift associated with frontal
passage. Ahead of the front, southwest winds will decrease on
the order of 5 to 10 mph the 30 to 60 minutes prior to frontal
passage. Then with the passage of the front, winds will quickly
veer from southwesterly to northwesterly and restrengthen with
peak gusts ranging from 35 to 40 mph. These quick changes in
wind speed and direction will have important implications in the
rate and direction in which fires spread should they be ongoing
during the passage of the cold front.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Red Flag Warning until 8 PM CDT this evening for NEZ011-012-
     015>018-030>034-042>045-050>053-065>068-078-088>093.
IA...Red Flag Warning until 8 PM CDT this evening for IAZ043-055-
     056-069-079-080-090-091.

&&

$$

DISCUSSION...Darrah
AVIATION...Darrah
FIRE WEATHER...Darrah