241
FXUS63 KGID 171759
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1259 PM CDT Fri May 17 2024

...Aviation Update...

.KEY MESSAGES...

- Rain and storms are possible across at least a portion of the
  area from Saturday evening through Thursday night.

- The highest chances (70% to 75%) of rain and storms will be
  Sunday into Sunday night and again Monday night.

- Severe storms are possible (about a 30% chance) on Sunday. The
  main threats are large hail and damaging winds.

&&

.DISCUSSION...
Issued at 351 AM CDT Fri May 17 2024

Today and tonight...

A broad upper trough extends from the Upper Midwest to the southern
Plains. Winds across south central and central Nebraska and north
central Kansas are out of the south with temperatures in the 50s and
60s. Winds will increase out of the south to southwest this
afternoon with mostly sunny to sunny skies. These conditions will
contribute to temperatures warming up into the 80s across most of
the area today. Winds will begin to transition from the southwest to
the northwest late tonight as a cold front moves into the area. Low
temperatures tonight will be in the mid 50s to lower 60s.

Saturday through Sunday night...

A broad upper trough will extend from the Pacific Northwest to the
northern/central Plains on Saturday. The cold front will continue
moving into the area on Saturday with northerly winds and clearing
skies. Winds will weaken during the afternoon and become more
easterly. High temperatures on Saturday will range from the mid 70s
to the mid 80s. A shortwave trough will move over south central and
central Nebraska and north central Kansas Saturday night and will
contribute to increasing rain and storm chances (up to around 50%).
Low temperatures Saturday night are expected to range from the low
50s to low 60s. An upper trough will dig southward over the western
part of the country on Sunday. Rain and storm chances (up to around
a 70% chance) will continue across the area on Sunday as shortwaves
move overhead. Dewpoint temperatures will be in the 50s and 60s
Sunday afternoon. Severe thunderstorms are possible (around a 30%
chance) on Sunday with fairly high CAPE, wind shear, and lapse rates
expected. High temperatures on Sunday will range from the upper 70s
to upper 80s with gusty southerly winds. Low temperatures Sunday
night will be in the low 50s to low 60s. Rain and storm chances (up
to near 75%) continue Sunday evening and decrease through the night.

Monday through Thursday night...

The upper trough over the western part of the country continues to
dig southward on Monday. Winds will generally be out of the north to
northeast on Monday with high temperatures in the mid 70s to mid
80s. Rain and storm chances (up to around a 75% chance Monday night)
will return to the area Monday afternoon into Monday night. Low
temperatures Monday night will range from the upper 40s to lower
60s. The upper trough to the west will move eastward on Tuesday
allowing for more rain and storms across the area. A cold front will
continue moving through the area on Tuesday with high temperatures
in the mid 60s to upper 70s. Low temperatures Tuesday night will be
in the lower 40s to lower 50s with continued rain and storm chances
(15% to around 30%). High temperatures on Wednesday will mostly be
in the 70s with a surface high pressure near/over the area. Low
temperatures Wednesday night will be in the mid 40s to mid 50s. A
warm up in temperatures is expected for Thursday with highs in the
mid 70s to mid 80s. Slight rain and storm chances (15% to around
20%) will be present Thursday with chances increasing up to around
40% Thursday night. Low temperatures Thursday night will mostly be
in the 50s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1259 PM CDT Fri May 17 2024

- General overview for KGRI/KEAR:
Very high confidence in VFR ceiling/visibility throughout, and
high confidence in dry/thunderstorm-free conditions. That
clearly leaves winds as the primary aviation concern, as not
only will this period feature a pronounced frontal passage and
directional change (with moderately-windy conditions both ahead
and behind it), but also several hours of moderately-strong low
level wind shear (LLWS) overnight into early Sat AM.

- Ceiling/visibility/precipitation details:
Although a few-to-scattered clouds mainly at-or-above 8K ft. are
likely at times, confidence is high in VFR conditions. As for
precipitation/thunderstorm potential, have left out any formal
inclusion, but that being said, there is the slightest chance
(only 5-10%) of a rogue, high-based shower passing through late
this afternoon and perhaps a sprinkle sometime early Saturday
morning.

- Winds:
Surface winds:
The overall-strongest winds of the period will focus this
afternoon into early this evening, and then again late in the
period behind a passing cold front. This afternoon into early
evening, southerly speeds will be sustained mainly 15-20KT/gusts
25-30KT. Overnight, speeds will gradually relax ahead of the
approaching cold front. Although not reflected in current TAFs
(too far out in time to include such detail), there will
probably be a 2-3 hour period (probably centered 10-13Z) with a
fairly light speed/perhaps variable direction. Then, around
13-14Z, the main frontal passage will occur, with north winds
quickly ramping up sustained around 20KT/gusts 25+KT.

- Low level wind shear (LLWS):
Have attempted to add some greater detail here, as now have two
LLWS groups to the overnight period to account for a directional
shift in the low level jet. First, from mainly 04-08Z, winds
within the lowest 1,500 ft. AGL will ramp up to around 45KT out
of the south-southwest. Then, from 08Z-11Z KEAR/08-12Z KGRI,
have introduced a separate group to account for a more "true"
southwesterly (possibly even west-southwesterly) directional
component. During this entire time, however, shear magnitude
between the surface and this level will be moderately-strong at
30-35KT. Any notable LLWS concerns will abate once the cold
front arrives.

&&

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

&&

$$

DISCUSSION...Schuldt
AVIATION...Pfannkuch