Lexington Weather

Lexington, Massachusetts, USA

53°F

4/30/2024 1:45am

Lexington Conditions: Overcast
Temperature: 53.4°F / 11.9°C
Dew Point: 47.5°F
Relative Humidity: 80%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.99 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Valentine, NE

        
000
FXUS63 KLBF 300546
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1246 AM CDT Tue Apr 30 2024

.KEY MESSAGES...

-  Thunderstorms return to the area tonight into tomorrow, and 
   persist nearly each day into early this weekend.

-  Elevated to near-critical fire weather conditions are 
   expected to develop across western Nebraska Tuesday afternoon
   with the combination of gusty northwest winds and low 
   humidity. 

-  Strong to severe thunderstorms will be possible both 
   tomorrow afternoon and again on Wednesday, primarily across 
   central (Wednesday) and north central (Tuesday/Wednesday) 
   Nebraska. 

-  Temperatures fluctuate around average (60s) through the 
   workweek with the passage of a few frontal boundaries, before
   climbing above average into early next week (mid/upper 70s).

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 400 PM CDT Mon Apr 29 2024

Currently, scattered showers have developed north of I-80, in a 
narrow corridor of elevated instability. Temperatures range from the 
low 60s in north central Nebraska to the lower 70s in southwest 
Nebraska. Aloft, an upper low was centered over ND/MN, with broad 
zonal flow on its southern periphery across the central Plains. 

For tonight into tomorrow, active weather returns to the area, as a 
quick moving upper low drops southeastward through the Intermountain 
West, reaching the northern Plains early tomorrow morning. At the 
surface, lee cyclogenesis begins across northeastern WY/eastern MT, 
dragging a warm front northward across the area into the Dakotas. 
The deep southerly flow will both boost lows tonight back into the 
40s, and lead to increasing moisture return flow into the area. This 
also looks to generate at least scattered showers in the broad warm 
advection regime overnight, though any severe threat with this 
activity looks low. Surface dewpoints will climb into the low 50s 
for areas east of HWY 183 by early tomorrow afternoon, leading to 
increasing instability.  For areas further west, the surface cold 
front should begin to push through the area from west to east, 
reaching the HWY 183 corridor by early afternoon. It is ahead of 
this boundary where convective development is anticipated, and a 
window will exist tomorrow afternoon for strong to severe storms, 
primarily east of HWY 11. Some uncertainty remains with respect to 
this however, largely tied to the speed of the aforementioned 
cold front and how much time is maximized in the warm sector 
during better diurnal heating. Deep layer shear profiles do 
support organized convection, with good speed shear aloft 
indicated in area forecast soundings. Large hail and damaging 
winds look to be the greatest threats, with initial 
discrete/semi-discrete updrafts presenting the best chance for 
hail before quick upscale growth leading to increased damaging 
wind potential. The threat locally will likely be brief, on the 
order of a few hours, and tied to the progression of the surface
cold front. This will need to be monitored closely as mesoscale
details become more clear. High temperatures will range from 
the 60s across northwest Nebraska where the surface front should
pass in the morning, to the low/mid-70s in southwest and 
central into north central Nebraska. 

Elevated to near-critical fire weather conditions look to develop 
across western Nebraska in the wake of the surface cold front 
tomorrow afternoon as well, as dry air is ushered into the area. 
This will send relative humidity values falling into the upper teens 
to low 20s for areas near and west of HWY 61. More concerning, as we 
mix out during the afternoon, winds will quickly strengthen from the 
northwest, tapping into a belt of 30-40kts of H7-H85 flow aloft. 
This should promote wind gusts approaching 40 miles per hour 
across western Nebraska with ample downward momentum transfer in
the well mixed boundary layer. The overlap of strong northwest 
winds and low humidity could lead to a period of near Red Flag 
conditions, considering current fuel conditions from recent 
greenup.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 400 PM CDT Mon Apr 29 2024

The threat for strong to severe storms persists into Wednesday, as 
yet another shortwave is progged to cross into the Plains by late 
Wednesday evening. At the surface, the aforementioned cold 
front will quickly stall across central Kansas, with lee 
cyclogenesis beginning across southeastern CO. This places our 
area in postfrontal broad east-southeasterly upslope flow. The 
easterly flow will pull the moisture that was ushered out behind
tomorrow's cold front right back into the area, with dewpoints 
increasing through the afternoon. The exact degree of moisture 
recovery remains somewhat uncertain, and this will determine the
areal coverage of any severe weather threat. Portions of 
central and north central Nebraska look to have the best shot at
higher dewpoints/greater instability, in closer proximity to 
the surface warm front in central Kansas. Hodographs look more 
than adequate to support severe weather across much of the area 
as well, with ample curvature in the lowest few kilometers and 
increasing speed shear aloft. Synoptically, this does resemble a
regime that is favorable for severe weather across western 
Nebraska as well, with convection initiating across the Front 
Range of Colorado in the broad upslope and pushing northeastward 
into the area. Should discrete storms sustain themselves into 
western and southwest Nebraska, a threat for large hail and 
damaging winds would be possible, again driven by the degree of 
instability with northeastward extent. 

The pattern remains active into the latter part of the workweek and 
into early this weekend, as multiple shortwaves look to push through 
the area in the quasi-zonal flow aloft. Nearly daily shower and 
thunderstorm chances exist through Saturday across much of the area. 
The degree of any severe weather threat will be driven by surface 
features each day, though mid/upper level flow does look strong 
enough to warrant at least some concern for severe weather. 
Mesoscale features will need to be watched closely, and additional 
threats for severe weather may exist as we wrap up the workweek.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1245 AM CDT Tue Apr 30 2024

VFR conditions are expected to prevail across western and north 
central Nebraska through tomorrow night. The primary aviation 
concerns over the next 24 hours are mostly wind related. Tonight, a 
strong low level jet brings LLWS concerns to both terminals and the 
surrounding areas. Before 09Z, LLWS concerns may be observed across 
all of western and north central Nebraska, but expect that LLWS 
concerns after 09Z will be primarily along and east of Highway 83, 
including both KLBF and KVTN. A frontal passage will bring numerous 
wind shifts tomorrow afternoon and evening, with winds eventually 
becoming strong northwesterly winds with strong gusts. Forecast 
soundings show potential for strong mixing, so gusts may end up 
being stronger than currently forecast. Due to the amount of wind 
shifts expected throughout the period, decided to focus more on the 
near term, and will attempt to catch the later wind shifts (after 
01Z) in the follow on forecasts. 

&&

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

&&

$$

SHORT TERM...Brown
LONG TERM...Brown
AVIATION...Richie