816
FXUS63 KLBF 201159
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
659 AM CDT Mon May 20 2024

.KEY MESSAGES...

* A slight risk of severe weather is possible on this evening
  (Monday evening) with large hail up to baseball size, severe winds
  up to 75 mph, and heavy rainfall up to 2 inches as the primary
  threats.

* Active weather continues through mid-week, although, severe
  potential remains low at this time.

* Cooler temperatures return on Tuesday with highs in the mid
  50s to low 60s before gradually warming through the end of the
  week (into the 70s by the weekend).

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 414 AM CDT Mon May 20 2024

The main weather story in the short term will be the potential for
severe thunderstorms this evening and into the overnight. Dewpoints
will increase across the region by late this morning and into the
afternoon as low level moisture advection intensifies. Moderate
instability will also develop across southwest and south central
Nebraska by the late afternoon. Ample instability will exist across
the region to support the development of supercells across the
Panhandle and into northeast Colorado. These storms will track
eastward into southwest and south central Nebraska by early evening.
Current model guidance suggests lapse rates above 7 C/km and shear
above 50 knots. This combined with significant CAPE (over 1500
J/kg), not to mention large CAPE in the -10 to -30 C layer, will be
enough to support very large hail (potentially up to baseball sized)
with these supercells. This environment will also create the
potential for significant wind gusts up to 75 mph.

The initial round of storms, the supercells, will have the greatest
potential to have the large hail and strong winds. As these storms
move eastward, another round of storms are expected to develop
behind them, which are not expected to be as intense as the
environment becomes worked over. However, these showers and
thunderstorms could still produce hail up to 1 inch and wind gusts
up to 60 mph for a few hours (through late evening). Eventually,
storms will weaken and congeal into a MCS for the remainder of the
overnight hours. This round will have the greatest potential to have
heavy rainfall with may result in localized flooding. At this time,
up to 2 inches of QPF are expected across southwest Nebraska and
into north central Nebraska. Have decided not to issue any flood
headlines at this time as this total rainfall will occur over 24 to
30 hour timeframe. Although, some flash flooding of low lying areas
or small streams is not entirely out of the question especially if a
heavier shower drops a half inch or more in a short period of time.
Will continue to monitor this as the event evolves tonight.

Heading into Tuesday, rain showers and embedded thunderstorms
continue throughout the day, although there are expected to be some
breaks. The severe risk is low for Tuesday as a cooler airmass
pushes in behind the departing front and the environment
remains well mixed. Still, we`ll have to be cognizant of the
flooding potential heading into Tuesday afternoon especially
across areas that have already seen heavy rainfall Monday night
and early Tuesday.

Regarding temperatures, highs will drop from the low 60s to low 70s
today into the mid 50s to low 60s on Tuesday. This will be nearly 10
degrees below normal for Tuesday (normals in the low to mid
70s).

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 414 AM CDT Mon May 20 2024

A series of disturbances will continue to impact Nebraska through
the weekend.  At this time, severe weather risk remains uncertain
with confidence remaining low on timing, track, and locations.
However, based on the latest guidance, best chance to see convection
will be in the late afternoon and early evening as diurnal heating
and instability is greatest. Will continue to monitor these systems
as the week progresses and those with outside plans in the evening
should stay weather aware and be prepared to make alternate plans.

For temperatures, cooler temperatures from Tuesday will give way to
a slow rise in temperatures into the weekend. Current model runs
indicate 850 mb temperatures to rise back into the 10 to 16 degree C
range by the weekend. While this will not equate to exceptionally
warm surface highs, especially with showers and thunderstorms each
day, highs will rise back to near normal in the mid 70s by the
weekend. Low temperatures also return from the low 40s on Tuesday
night into the low 50s by Saturday night which is just slightly
above normals for this time of year.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 655 AM CDT Mon May 20 2024

VFR conditions through the day will degrade this evening as
thunderstorms, heavy rain, and low-stratus invade western
Nebraska.

Mid-level clouds will settle in around midday but should remain
above 3kft AGL. As thunderstorms move into southwest Nebraska
this evening, expect quick deterioration of flight rules at LBF
with MVFR conditions likely and IFR/LIFR possible in areas of
heavy rain. Thunderstorms will likely be numerous with strong
winds and hail possible as well, threatening the terminal for
much of the late evening. For VTN, the bulk of the significant
severe should remain south of the terminal but rain and
thunderstorm chances increase by early Tuesday morning. Winds
will also increase out of the east-northeast toward the end of
the period with gusts in the 20 to 30 knot range.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...Kulik
LONG TERM...Kulik
AVIATION...NMJ