445
FXUS63 KLBF 192020
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
320 PM CDT Fri Jul 19 2024

.KEY MESSAGES...

- Scattered severe storms are possible late this afternoon and
  tonight. The hazards are damaging winds, large hail and
  locally heavy rainfall which may cause flooding in some areas.
  The risk of a tornado is low but not zero.

- Isolated thunderstorms are possible Saturday through Monday.
  The risk of severe storms is low.

- Dry weather and warming temperatures are expected Tuesday
  through Friday.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 315 PM CDT Fri Jul 19 2024

A plume of subtropical moisture will remain across wrn/ncntl
Nebraska this afternoon and this evening. PWAT values of 1.25 to
1.50 inches will be in place. Modest drying is expected after
midnight. Thereafter, PWAT falls to an inch or less Saturday and
Saturday night. This drying will be accompanied by cooler air aloft
with h700mb temperatures falling to 5 to 9 C.

Severe weather chances this afternoon and this evening hinge on an
increase in wind speeds aloft, most notably h500mb winds
increasing from 30kt to around 40kt. Warm air advection moving
north through KS is modest and being intercepted by ongoing
storms but warmer air aloft is lurking to the west across the
high plains of Colo and WY. The first round of 2 or perhaps 3
rounds of thunderstorms moved through wrn/ncntl Nebraska this
afternoon. A second round is attempting to organize across SD
and WY. Given that satellite shows the dynamics extending north
into wrn SD/nern WY, a second round of late afternoon/evening
storms seems likely. The very dry air across the high plains
make significant wind gusts the primary concern. High PWAT and
the potential for cell mergers, back-building and repeat storms
support the WPC excessive rainfall outlook highlighting swrn and
ncntl Nebraska for flood potential.

A third round of thunderstorms is possible late this evening and
overnight as temperatures aloft cool but the latest NAM12, HREF and
NAMnest are quiet about this. The RAP model supports scattered
storms late tonight. The model soundings show abundant CAPE, around
2500 J/KG but the winds aloft are backing with height which might
favor back-building and excessive rainfall vs severe weather.
Nonetheless, satellite and radar shows storms firing across ern MT
this afternoon and this disturbance will likely move south through
Nebraska overnight.

The peak heating period from 4 pm to 9 pm today would appear to be
the most favored time for severe weather but not all models agree on
this. The forecast leans toward the more aggressive NAMnest which
shows scattered storms developing late this afternoon into the
evening.

Isolated rain chances are in place Saturday, mainly for daytime
heating. The forecast is dry Saturday night. It is worth noting the
jet stream will shift west running north and south along the Laramie
and Front ranges Saturday. It is in this area the models show storms
forming. This activity would likely be steered south southeast and
remain west of wrn/ncntl Nebraska.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 315 PM CDT Fri Jul 19 2024

Isolated to low-end chance POPs are in place Sunday and Monday.
Winds aloft at h500-300mb will be weak, generally less than
30kts and the risk of severe storms would likely remain low.

The forecast is dry Tuesday and beyond for a few reasons.
Upper level moisture in the models will be spartan and temperatures
aloft will be on the rise. Wrn/ncntl Nebraska will remain in
northwest flow which could support storm development off the Black
Hills or the Big Horns but the models suggest moisture will be too
limited.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1220 PM CDT Fri Jul 19 2024

VFR conditions are expected to prevail outside of thunderstorms
across western and north central Nebraska into tonight.
Widespread thunderstorm development will continue across much of
the area this afternoon and evening, with brief MVFR CIGs and
visibilities, along with gusty and erratic winds, possible
inside storms. Timing and placement of thunderstorm activity
remains low confidence, and amendments will likely be needed at
both KLBF and KVTN as confidence grows.

Thunderstorms exit the area tonight, with an expansion of low
stratus across north central Nebraska. A period of IFR is
possible for north central Nebraska terminals tomorrow morning.
Winds remain erratic across the area with the passage of
thunderstorm outflow boundaries today, with a return of light
northerly winds overnight.

&&

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

&&

$$

SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Brown