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000
FXUS63 KGID 281204
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
704 AM CDT Sun Apr 28 2024

...Aviation Update...

.KEY MESSAGES...

- These first 24 hours include various "pesky variety" issues
  including: 1) perhaps a few strong storms flaring up in our
  eastern zones sometime this morning/early afternoon...2)
  perhaps some fog issues this morning mainly in our eastern
  half...3) Perhaps some frost development late tonight mainly
  in our western zones. Please note that confidence in any of
  these potential issues is not overly- high.

- Monday looks to be the overall "quietest" weather day of the
  next several, with warmer temps and the return of sunshine
  allowing some of our more saturated spots to dry more
  efficiently (and allowing this forecaster to get some mowing
  done).

- Although not currently anticipating any "powerhouse" upper
  level low pressure systems like the recent and ongoing one
  have been, we resume an active upper level weather pattern
  Tues-Sat as a parade of several, mainly lower-amplitude
  disturbances pass through the region. As a result, our
  forecast features several chances for rain/thunderstorms.

- Although there are no "truly concerning" severe thunderstorm
  chances evident just yet, there are at least a couple of
  periods to watch, namely Tues afternoon (SPC has assigned a
  Marginal Risk to our eastern zones) and potentially more so
  Wed-Wed night (although so far SPC has only officially
  included our extreme southeast in a Day 4 "Slight Risk
  equivalent" area.

- Temperature-wise: fairly typical mid-spring conditions
  prevail, with highs on most days in the 60s/70s and lows on
  most nights in the 40s to low 50s. The main exception is right
  away today-tonight (which will likely be the chilliest of our
  7-day forecast).

&&

.DISCUSSION...
Issued at 532 AM CDT Sun Apr 28 2024

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

- Honestly nothing major, but as noted above, particularly Wed
  afternoon-night is starting to carry a bit more of a signal
  for being our next chance for possible widespread thunderstorm
  activity and perhaps also at least a limited severe
  storm/localized heavy rain threat.


-- 7-DAY FORECAST DETAILS (heavily focused on the first 24
 hours):

- CURRENT/RECENT WEATHER SCENE AS OF 430 AM:
Will start off by acknowledging that the potential severe storm
threat for mainly our southern counties yesterday afternoon-
evening was (fortunately) mostly low-key. While we issued 5
Severe Thunderstorm Warnings for mainly hail threats the primary
surface warm front/low level instability axis stayed entirely
south of our coverage area (CWA), which was the primary reason
our southern zones were spared a potentially-concerning tornado
threat. Speaking of tornadoes and briefly going back to Friday,
look for damage survey results from Friday
(Buffalo/Sherman/Howard/Greeley counties) to become available
over these next few days.

Getting back on track to current/very recent weather, instead of
the late-night/early AM hours being stormy, it has instead ended
up being mainly dry, although spotty showers and patchy drizzle
is out there, along with areas of mainly (thus far) light fog.
In the big picture of the mid-upper levels, water vapor imagery
and short term model data clearly confirm the heart of a large-
scale/closed low pressure system is centered over western NE,
slowly trudging east-northeast. Meanwhile at the surface, an
elongated axis of low pressure (only around 1004 millibar
magnitude) is aligned from near the extreme southeast corner of
our CWA in north central KS, southward into OK. As a result,
essentially our entire CWA is in the cool sector of this system,
as evidenced by widespread low clouds, pockets of fog/drizzle
and mainly northerly winds generally 5-15 MPH.


- TODAY-THIS EVENING:
Breaking things down by different topics (not necessarily
chronological)...

1) Big picture and thunderstorm/rainfall expectations:
Aloft, the aforementioned upper low currently over western NE
will slowly trudge east-northeast reaching eastern parts of the
NE/SD border by mid-evening. At a glance, this is concerning
considering that we just had a somewhat similar setup leading
into Friday`s regional tornado outbreak. However, speaking
solely for OUR CWA, today is fortunately a completely "different
animal", and thus carries a very minimal severe storm threat.
The biggest difference from Friday is the track/intensity of the
surface low. Instead of a powerful low crossing through our
northern CWA, today`s weaker surface low will instead track
north-northeast from its current position over north central KS,
to east-central NE by mid-day, to western IA by evening. In
other words, this low will BARELY skirt our extreme eastern
fringes as it passes, leaving the vast majority of our CWA in
the cool/more stable sector (marked by west-northwest winds),
and at least slightly west of the main lower-level instability
axis this afternoon-early evening (thus why SPC has all but kept
the Marginal Risk just east of us. All that being said, there is
still a chance that at least a brief flare-up of strong storms
(mainly with a small hail/heavy rain threat) could yet
materialize mainly in our far eastern zones (mainly counties
east of Highway 281) at some point this morning/maybe early
afternoon. It all depends on whether increased upper forcing
arriving from the southwest can tap into an axis of elevated
instability (most-unstable CAPE at least 500 J/kg) in our
eastern zones. This will bear watching through perhaps as late
as 1-2 PM, but again, this would mainly be for a marginal hail
threat, as anything potentially more concerning should focus to
our east. Kept at least low chances for weaker rain showers
and/or sprinkles going most all areas through the day (and
although not officially in our forecast possible drizzle
especially this morning), but rain chances will steadily
diminish from southwest-to-northeast as the day wears on.

2) Winds/temperatures/AM fog potential:
While the majority of the day will feature fairly steady north-
northwest breezes on the backside of the surface low (sustained
10-20 MPH/gusts up to at least 25 MPH), especially the eastern
1/3 of our CWA will experience a period of lighter/more variable
direction winds this morning in closer proximity to the surface
low. Not surprisingly, these lighter winds have already resulted
in increased (mainly light so far) fog development. Some models
(such as HRRR) suggest that a period of at least patchy heavier
(perhaps even dense?) fog could take hold for a time this
morning (mainly before 10 AM), and a generic "areas of fog" has
been added to our morning forecast for several central/eastern
counties to account for this. As for sky cover today, widespread
low clouds will largely hold firm today especially in the
northeast 3/4 of our CWA. However, at least partial later-day
sun could try making an appearance mainly in our far south-
southwest zones. Nudged down high temps slightly from previous,
with our far northern/west central counties struggling to even
make the low 50s, with mid-upper 50s central and any low to
possibly mid 60s focused mainly in our KS zones and also far
eastern NE zones (Highway 81 corridor).


- OVERNIGHT:
Although a few isolated/rogue showers or sprinkles could still
be in parts of our north-northeast zones until shortly beyond
sunset, confidence is high in a dry overnight with skies
probably clearing fairly steadily especially over the southwest
2/3 of our CWA (perhaps a bit more potential for lingering lower
clouds north-northeast). At the surface, steadier northwest
breezes in the evening will turn more westerly overnight and
lighten down mainly into the 5-10 MPH range. This sets the stage
for what should be the chilliest of the next several nights,
with low temps currently aimed mid-upper 30s most areas. While
sub-freezing temperatures are quite unlikely, at least
patchy/limited frost development cannot be ruled out toward
sunrise Monday, particularly in parts of several counties
along/west of Highway 281. Considered issuing a formal Frost
Advisory, but with at least some lingering uncertainty on how
efficiently skies clear (and resultant low temps) held off for
now, while still acknowledging in our Hazardous Weather Outlook
(HWOGID).


- MONDAY-MONDAY NIGHT:
This will likely be the overall "quietest" 24 hours of the week,
as we experience a brief period of very weak upper ridging in
the wake of the departing system. Our forecast remains dry CWA-
wide, and we should see plentiful sunshine, although a few
models give subtle hints that maybe some very spotty showers
could perhaps drift into mainly our KS zones during the
afternoon-evening (considered too low probability for forecast
inclusion). Otherwise, daytime breezes will generally average no
more than 10-15 MPH (a few gusts around 20) as direction
transitions to more west-southwesterly. The net result is a nice
warm-up with highs upper 60s-low 70s most areas, and mid 70s
mainly in KS. Mon night will be warmer with lows upper 40s-low
50s (no frost threat).


- TUESDAY-TUES NIGHT:
The first of several upper disturbances passes through, sending
a weak cold front through our CWA and turning winds north-
northwesterly during the afternoon-evening. Shower/thunderstorm
chances return to mainly our northern/eastern zones during the
day-early evening, and while we will have to watch for a
possible/limited severe threat (SPC Marginal Risk currently
includes several eastern counties), latest deterministic models
suggest the main threat for possible afternoon severe storms
along the cold front should remain slightly to our east-
southeast.


- WED-THURS:
Another disturbance approaches and passes through, sending
another cold front through mainly Wed night-Thurs daytime. Ahead
of this system, there are indications that a bit more
instability could build, and at least a limited threat for
severe storms/heavy rain could unfold mainly Wed afternoon-
overnight (we`ll need to keep an eye on this).


- FRI-SAT:
More periodic chances for rain showers litter our forecast, but
confidence is admittedly very low in the details at this time.
If anything we appear to be a little cooler/more stable in the
wake of the Wed night-Thurs cold front, so kept precip as just
generic rain showers with no thunder mention at this time.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 704 AM CDT Sun Apr 28 2024

- General overview for KGRI/KEAR:
The majority of the period will likely feature sub-VFR ceiling
(ranging from LIFR to MVFR), with a period of IFR/MVFR
visibility also likely these first few to several hours in light
fog/drizzle and passing showers. Precipitation- wise,
isolated/scattered showers will continue to roam the general
area mainly through these first 6 hours, with a few weak
thunderstorms not out of the question. Wind-wise, no big
concerns, but moderately-breezy speeds with gusts into the
20-25KT range will occur especially this afternoon, as direction
shifts from more northerly to more west-northwesterly with time.

- Ceiling/visibility and rain/thunderstorm details:
Ceiling:
Starting off this morning, LIFR will prevail for a few hours,
with a very gradual improvement to IFR/MVFR expected as the day
wears on. Model guidance remains a bit murky regarding when a
return to outright-VFR will occur, but based on latest trends
have delayed this somewhat, now very tentatively aimed 05Z
KEAR/08Z KGRI.

Visibility:
Although any passing showers/thunderstorms could briefly enhance
sub-VFR visibility this morning, a combination of fog/drizzle is
the main culprit for what will likely be at least 3-6 hours of
potential IFR/MVFR categories. Fairly high confidence in a
return to VFR by around 18Z, UNLESS patchy drizzle lingers
(which is possible).

Rain/thunderstorms:
Mainly spotty (isolated to scattered) rain showers and possibly
a few weak thunderstorms remain "fair game" through at least
15-18Z. Expected coverage/duration do not warrant any
prevailing/TEMPO groups at this time (aside from light drizzle),
so have kept a generic "vicinity shower" (VCSH) mention for now
through 18Z.

- Winds:
As a surface low pressure system gradually tracks east of the
area, direction will swing around from more northerly to more
westerly with time. Prevailing speeds through most of the period
will average between 10-15KT, with gusts of 20-25KT probable
especially this afternoon. However, speeds will drop solidly
under 10KT very late in the period Monday morning.

&&

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

&&

$$

DISCUSSION...Pfannkuch
AVIATION...Pfannkuch