Lexington Weather

Lexington, Massachusetts, USA

59°F

5/20/2024 8:29pm

Lexington Conditions: Clear
Temperature: 59.4°F / 15.2°C
Dew Point: 53.2°F
Relative Humidity: 80%
Wind: Calm, 10-min avg: Calm, gust: 1 mph
Barometer: 29.94 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for North Platte, NE

        
000
FXUS63 KLBF 170002
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
702 PM CDT Thu May 16 2024

.KEY MESSAGES...

- Hot and dry tomorrow with highs approaching 90 and elevated/near 
critical fire weather conditions

- Thunderstorms appearing more likely (60%+) Sunday and Monday with 
severe weather possible, including all hazard types

- Brief stint of cooler/milder temps early in the week, then
  warming again by midweek with continued low end (<30%)
  moisture chances

&&

.SYNOPSIS...
Issued at 352 PM CDT Thu May 16 2024

The heart of an upper trough has moved downstream of the forecast 
area today, with its axis roughly lining up with the Missouri River, 
and placing western Nebraska into broad northwesterly flow aloft. A 
closed upper low in the process of getting absorbed into the main 
flow also lies to the southwest, currently centered over New Mexico. 
Toward the surface, high pressure has gained control of the central 
and northern Plains in the wake of a cool front. A weak boundary or 
surface trough stretches along the High Plains, cutting across the 
panhandle.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 352 PM CDT Thu May 16 2024

This evening into tonight... The surface high edges eastward, 
transitioning low level flow to more return southwesterly. WV/IR 
imagery indicate a couple rounds of mid/high clouds upstream, likely 
associated with weak PV anomalies. A weak low level jet also 
develops with guidance generally suggesting 30 kts at H85 in the 
Sandhills. The combination of the strengthening southerly flow and a 
thermal ridge will jump start the warm air advection scheme, shown by 
6-7C rises over the last 24 hours. Went with a general blend for min 
temps, which lines up near the median of the NBM envelope. Forecast 
lows range from upper 40s panhandle to mid 50s north central. 

Tomorrow and tomorrow night... Upper flow briefly becomes quasi-
zonal across Nebraska as the trough over the Great Lakes evens out 
and a new trough digs upstream in the northern Rockies. A surface 
low also spins up near the Black Hills and drags a cool front 
through the Sandhills after dark. In the meantime, fair skies and 
southwesterly low level flow will help accelerate warm air advection 
further. Guidance is in good agreement with H85 temps ranging 20-25C 
across the forecast area, which is a good 5C warmer than today. 
Again used a general MAV/MET/ECS blend for max temps, which resulted 
in a subtle upward trend over the previous forecast. While new 
forecast highs sit in the upper 80s, these values correlate to the 
lower end of the NBM envelope. Would not be surprised if later 
forecasts need bumped up another degree or two, especially with 
NAEFS ensembles suggesting 97%ile of climo. The cool front is 
progged to cross overnight, primarily 06-12z. Questions remain 
whether forcing can overcome marginal moisture to result in precip. 
Left forecast dry as of now, but CAMS suggest iso/sct light rain 
showers or sprinkles.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 352 PM CDT Thu May 16 2024

The weekend starts with northerly flow behind the cool front, 
resulting in relief from Friday's heat. Highs should generally stay 
in the 70s, accompanied by nearly full sunshine. Attention quickly 
turns to Sunday when the pattern turns much more active. Another 
lobe in the large scale upper trough tilts the axis to negative, 
transitioning the flow to southwesterly for the Plains. Southerly 
low level flow is basically unimpeded from the Gulf, which helps to 
push dew points well into the 50s. A lead mid-level shortwave 
intersects a warm front passage early in the day and a dryline and 
cool front later on. Parameters seem to be pulling together for a 
severe weather scenario for western and north central Nebraska. 
Abundant energy in the form of 1500+ j/kg MUCAPE and very steep mid-
level lapse rates (8+ C/km) combine with strong deep layer shear of 
40+ kts. Preliminary forecast soundings resemble "loaded gun" 
profiles, while hodographs indicate consistent veering in the low 
levels. While convective evolution may be fuzzy, initial mode would 
likely be supercellular for any development. Agree with the SPC 
assessment of all hazard types are on the table. The bulk of the 
forcing shifts east on Monday, but the post-frontal environment on 
Monday could still comprise steep lapse rates and strong shear, 
despite the fairly limited instability. Depending on precip coverage 
during Sunday's event and Monday's new development, may need to 
monitor excessive rainfall risk. The heart of the deep trough 
crosses the central Plains on Tuesday, then a ridge gradually builds 
in over the Rockies heading into midweek. Low end PoP persist into 
Wednesday, while temps range from coolish Mon (60s north/70s south) 
to seasonable by Wed (70s/maybe 80).

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 701 PM CDT Thu May 16 2024

Thunderstorms upstream coming off the Black Hills are moving 
toward Nebraska but are expected to diminish with loss of 
heating after sunset, so will not include any mention at KVTN 
but will monitor closely and amend if needed.

Otherwise, VFR conditions will persist across central and
western Nebraska through the valid period. A low level jet will
become established southwest to northeast with the axis roughly
from KIML to KONL. Will include a mention of low level wind
shear at KLBF but expect KVTN will remain far enough from the
jet axis to necessitate a mention in the TAF. After daybreak
Friday once diurnal hearting becomes established, expect some 
gusty conditions with southwest winds gusting to around 22kt.


&&

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

&&

$$

SYNOPSIS...Snively
SHORT TERM...Snively
LONG TERM...Snively
AVIATION...MBS