Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 121138
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
638 AM CDT Tue Mar 12 2024

...Aviation Update...

.KEY MESSAGES...

- While lighter winds will "save" most of our coverage area
  (CWA) from near-critical/critical fire weather concerns today,
  especially counties along/south of the NE/KS border will be
  solidly near-critical (see separate FIRE WEATHER section below
  for all further fire weather discussion).

- Concern is gradually increasing that Wed late afternoon-
  evening could feature our first (at least limited/localized)
  severe thunderstorm threat of 2024...particularly within our
  KS zones northward to roughly the Highway 6 corridor. Large
  hail probably the overall-highest threat.

- The localized severe storm threat aside, most areas
  especially along/north of Highway 6 appear favored to receive
  beneficial rainfall of generally 0.50-1.00" with the Wed-
  Thurs system...but given the convective nature there will
  surely be lower/higher exceptions.

- Although our current official forecast renders any possible
  snow threat within our CWA on the backside of the system
  especially Thurs night as very negligible, this will need
  monitored very closely (especially in light of last week`s
  sneaky/over-achieving snow storm).

- Our forecast is currently a dry one Friday daytime-Monday,
  with seasonable high temps mainly in the 40s or 50s.

&&

.DISCUSSION...
Issued at 511 AM CDT Tue Mar 12 2024

Up-front "administrative note":
With the vast majority of legitimate forecast concerns focused
within these first 3 days, the remainder of this discussion will
be very "short term heavy" with little-to-no discussion of
Friday- Monday beyond what was briefly touched on above.


-- PRIMARY CHANGES TO THIS 7-DAY FORECAST PACKAGE VERSUS THE
 PREVIOUS (Monday afternoon) ONE:

- From a purely temperature, precip chance (PoP), wind speed
  etc. standpoint, there was honestly very minimal change
  (although PoPs) were nudged up a bit more for Wed evening-
  overnight in most of especially our Nebraska CWA (widespread
  60-80 percent).

- The overall-biggest change is more so from a "messaging
  perspective", as Wednesday`s increasing strong-to-severe
  thunderstorm threat has honestly gotten relatively sparse
  attention in both our official text products, social media
  posts/graphics etc. for something that is now only ~ 36 hours
  away (solidly into the Day 2 time frame).


-- SHORTER TERM FORECAST DETAILS FOCUSED SOLELY ON THESE NEXT 72
 HOURS (through late Thurs night/early Friday AM):

- CURRENT/RECENT WEATHER SCENE AS OF 430 AM:
Honestly no real surprises to speak of, as it`s been a very
quiet night featuring only various batches of passing mid-high
level clouds. In the mid-upper levels, water vapor satellite and
short term model data confirm that we reside under west-
southwesterly flow aloft, just downstream from an evident, but
moisture-starved shortwave heading our direction out of CO. At
the surface, our breezy/windy southerly winds from Monday have
gradually departed to the east, as a weak low pressure center
developing over northwest KS has now allowed a weak front to
roughly bisect our CWA from southwest to northeast (light
northerly breezes to its north...light southerly breezes to its
south. Low temps are on track to bottom out mainly mid-upper 30s
west to low-mid 40s east (although a fair amount of high clouds
could keep some spots from dropping quite as far as forecast).

- TODAY/DAYTIME:
Today is another "guaranteed" dry day, with solidly near-
critical fire weather concerns in our southern CWA by far the
main issue (see separate section below for all further on this
topic). Aloft, the aforementioned/approaching shortwave trough
will track over the heart of the Central Plains today, but due
to such sparse moisture levels locally, it will not trigger
precip (showers/storms) until it gets well east of us late this
afternoon-evening (especially the KS/MO border area). For us
locally, the main impact aloft will be a morning filled by
plentiful high level clouds, before skies clear quite a bit this
afternoon on the backside of the departing wave. At the
surface, the low currently over northwest KS will track due east
roughly along the I-70 corridor into far northeast/east-central
KS by sunset. As this low passes by to our south, relatively
light (especially compared to yesterday) northerly breezes will
prevail most of today, with sustained speeds/gusts generally
only 10-15 MPH/15-20 MPH in most of our area, but slightly
stronger sustained speeds 15-20+ MPH/gusts 20-25+ MPH focused
especially along/south of the NE/KS border (overall-strongest
winds Rooks County KS area). High temps today were changed very
little, aimed 69-73 most areas.

- THIS EVENING-TONIGHT:
It will remain dry as we reside "in between" disturbances aloft,
with only a gradual increase in mid-high clouds as the night
wears on. Winds will be light (mainly well under 10 MPH) and be
fairly variable in direction, but if anything favor southerly to
southeasterly. Low temps were nudged down 1-2 degrees at most,
but with most of the CWA aimed 37-42 degrees (fairly uniform).

- WEDNESDAY DAYTIME-NIGHT:
The majority of the daytime hours (especially pre-4 PM) will
likely be fairly uneventful, with only an increase in east-
southeasterly breezes in response to deepening surface low
pressure over southwest KS (sustained speeds most of our CWA
10-20 MPH/gusts 15-25 MPH). However, especially by late
afternoon, things COULD get fairly interesting rather abruptly.
While models, as always, differ on the finer details, higher-res
solutions such as from the latest HRRR/NAMNest fire up a
generally west-east cluster of strong to severe storms mainly
within 40 miles either side of the NE/KS border, along an
effective warm front. One of the biggest question marks at this
time probably surrounds just how far north the warm
front/instability axis will reach (our some models lifting it
too far north into our CWA?). Assuming it DOES get into our
southern zones, the environment will become conducive for at
least a few severe storms/supercells with probably primarily a
large hail threat (latest RAP suggests mixed-layer CAPE perhaps
as high as 1000-2000 J/kg range in the presence of at least
30-40KT of deep-layer shear). At least for now, we are expecting
surface dewpoints to "only" reach the upper 40s to around 50
near this boundary, which in theory would be a touch too dry to
support a legitimate tornado threat, but this bears watching as
low- level shear profiled COULD support at least a brief/weak
threat (although this would seem to more favor areas JUST east
of our southern zones). No matter how much (or little) of a
severe storm threat materializes late Wed afternoon-evening, a
larger "mass" of showers/mostly weaker storms is expected to
lift northward across much of the CWA...bringing needed
rainfall to especially the northern half of the CWA. Any "true"
severe storm threat would likely end by midnight, as winds turn
northerly and usher in increasingly-stable/cooler air, although
at least scattered showers/non-severe storms would persist.
Temp-wise, highs Wednesday were changed little, still aimed mid-
upper 60s west to low 70s east, and lows Wednesday night are
aimed upper 30s-mid 40s (keeping precip type as rain).


- THURSDAY DAYTIME-NIGHT:
Not surprisingly, question marks in the finer details further
grow getting into this Day 3 time frame. Aloft, our forcing
gradually decreases as the disturbance responsible for Wed-Wed
night`s activity gradually departs/shears out to the northeast.
The biggest uncertainties surround coverage and to some degree
type of precipitation, as while models such as NAM/ECMWF favor
more scattered coverage at best of mainly chilly rain showers,
recent GFS solutions try to support a more organized band of
precip especially within our northern/western zones (which MIGHT
imply a "sneaky" snow event). Just a lot of question marks here.
What is more certain is that Thursday will be a blustery, cooler
day in the wake of Wed night`s cold front, with northerly winds
sustained 20-30 MPH/gusts 25-35+ MPH. High temps were nudged
down 1-2 degrees (and very possibly not enough), but now aimed
from mid- upper 40s west to 50s far east and south into KS
zones. Any lingering/spotty precip from this system is currently
expected to end by sunrise Friday AM, with morning low temps
ranging upper 20s-mid 30s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 638 AM CDT Tue Mar 12 2024

- General overview for KGRI/KEAR:
Honestly, this about as "quiet" of a period as you will find
around here in mid-March. There is very high confidence in VFR
ceiling/visibility and precipitation-free weather, with only
varying degrees of passing high-level clouds mainly at-or-above
15K ft. Winds will also be a minimal issue, with sustained
speeds mainly at-or-below 10KT.

- Wind details:
Sustained speeds throughout the period should largely prevail
at-or-below 10KT, and even the strongest gusts (mainly between
15-20Z) should not exceed 15-17KT. Direction-wise, northerlies
will prevail during the first half of the period today, before a
more variable (but if anything probably favoring southerly)
direction kicks in overnight.

&&

.FIRE WEATHER...
Issued at 511 AM CDT Sun Mar 10 2024

- Regarding solidly near-critical and at least brief/localized
  critical fire weather conditions likely in our southern CWA
  this afternoon:

Today is one of those "oh so close" fire weather setups where if
forecast winds were just a few MPH stronger the scales would
likely have been tipped toward formal Warning issuance for at
least a few counties along/especially south of the NE/KS border
(particularly for the Rooks County KS area which is technically
clipped by an SPC "elevated" category). However, for now have
opted to advertise today as a solidly-near-critical situation in
this area, with both our Hazardous Weather Outlook (HWOGID) and
a Special Weather Statement (SPSGID) highlighting the solidly
near-critical situation within 10 of our southern-most
counties,

As for the meteorological parameters themselves, the vast
majority of our CWA will see low relative humidity (RH) this
afternoon (most places bottoming out 15-25 percent). Fortunately
though, the bulk of especially our Nebraska counties are
expected to see the fire weather threat muted by generally
northerly wind gusts averaging UNDER 20 MPH this afternoon.
However, the potential for near-critical gusts of 20-25 MPH
increases from especially Furnas/Harlan/Franklin/Webster and
southward into our KS zones, with Rooks County KS in particular
of greatest concern to observe at least 1-2 hours of 25+ MPH
gusts out of the northwest, especially between 2-4 PM...thus
flirting perilously close with critical fire weather conditions.
Observational trends will certainly need monitored closely
today, just in case Warning issuance becomes more justified.


- Briefly peeking ahead:
Fortunately, a combo of various factors including increased low
level moisture and/or precipitation and/or cooler temperatures
should give us a break from near-critical (or worse) fire
weather concerns especially Wed-Fri. However, at least localized
near-critical parameters could come back into play for Sat-Mon
(just too far out in time/too uncertain to include in products
such as HWOGID yet).

-- NOTE:
NWS Hastings typically defines CRITICAL fire weather as the
overlap of BOTH 20-percent-or-lower RH and sustained winds/gusts of
20+ MPH/25+ MPH (for 3+ hour duration).

NWS Hastings typically defines NEAR-CRITICAL fire weather as the
overlap of BOTH 25-percent-or-lower RH and sustained winds/gusts
15+MPH/20+ MPH.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.

&&

$$

DISCUSSION...Pfannkuch
AVIATION...Pfannkuch
FIRE WEATHER...Pfannkuch


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