Lexington Weather

Lexington, Massachusetts, USA

56°F

5/20/2024 10:14pm

Lexington Conditions: Clear
Temperature: 55.9°F / 13.3°C
Dew Point: 52.2°F
Relative Humidity: 87%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.96 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for North Platte, NE

        
000
FXUS63 KLBF 190603
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
103 AM CDT Sun May 19 2024

.KEY MESSAGES...

- An active weather pattern brings a variety of impacts, 
  including severe weather and heavy rainfall Sunday through 
  Tuesday. 

- A limited threat for late season frost, but cannot rule out a
  localized threat following a cool down mid week. 

- The pattern remains active through the week, brining the
  potential for precipitation nearly every day. Confidence on
  daily precipitation chances remains relatively low, due to
  uncertainty in exactly how the upper level pattern evolves.

&&

.SYNOPSIS...
Issued at 235 PM CDT Sat May 18 2024

Upper air analysis and satellite imagery this morning reveal an 
upper level low over north central North Dakota, and a developing 
shortwave over western Washington. At the surface, a low pressure 
system is located over Winnipeg, Manitoba this morning, with a cold 
front extending south through north central Kansas. High pressure is 
observed over the Nebraska Panhandle.

&&The main aviation concern will be the development of rain and 
thunderstorms during the day on Sunday. Confidence remains low on 
timing and location, but at this time the best chance to see 
thunderstorms will be in the afternoon mainly across southwest 
Nebraska and into the Sandhills. Large hail and strong gusts will be 
the main threats as well as reductions in visibility due to intense 
falling rain. The strongest storms should remain south of KVTN. 

.SHORT TERM /THROUGH MONDAY/...
Issued at 235 PM CDT Sat May 18 2024

Tonight, the stage becomes set for several days of active weather. 
As surface high pressure ejects to the east, a weak surface boundary 
may be the focus for some showers and thunderstorms this evening 
through Sunday morning, particularly across southwest Nebraska. As 
the nocturnal low level jet settles in, a plume of warm, moist air 
advects into the region. While this is happening, a low 
pressure system over Wyoming is expected to form and mature, 
developing a warm front and cold front before it heads east.

The main forecast challenge in the short term will be how long these 
showers and thunderstorms linger, which sets up two main scenarios 
for Sunday evening. If the storms exit the region more quickly, as 
seen in HRRR guidance, there is a greater period of daytime heating, 
and as such a greater severe weather threat Sunday afternoon and 
evening. These solutions are presenting decent surface based CAPE 
and generally initiate storms along a line through most of the 
region. On the other hand, there is some slower guidance such as the 
NAM Nest, which holds the cloud cover from showers and storms a bit 
longer, limiting the daytime heating. These slower solutions limit 
the surface based CAPE, keeping storms more elevated in nature, and 
in some cases wipes the thunderstorm threat out by tomorrow evening. 

What does remain consistent is the plume of moisture ahead of the 
approaching system. Additionally, forecast soundings all tend to 
show a potential severe weather environment tomorrow evening, with 
ample CAPE and shear profiles. If the daytime heating can erode the 
capping layer, and storms can tap into the surface based layer, the 
environment seems primed to produce large hail and damaging winds. 
If the cap remains in place, then convection likely remains 
elevated, still with large hail potential, but may end up being 
hindered unless it can tap into the surface moisture.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 235 PM CDT Sat May 18 2024

Showers and thunderstorms Sunday night begin to taper off after 
midnight, giving a brief dry period on Monday morning. By the 
afternoon, another batch of showers and thunderstorms develops to 
the west and begins to track across the forecast area. Overnight 
Monday into Tuesday continues to be highlighted as the peak intensity 
of this precipitation event. Current guidance suggests that forecast 
precipitable water values will exceed the climatological 90th 
percentile. To further back this, ensemble guidance is now 
highlighting portions of north central Nebraska and the Sandhills 
with a 60 percent chance of exceeding 1 inch of rain in 24 hours. As 
for expected amounts, followed with the Weather Prediction Center 
guidance which calls for storm total rainfall around 1 to 3 inches 
across the region from tonight through early Wednesday morning. 
Currently, the highest amounts are expected across the Sandhills, 
but with the convective nature of the rain, locally higher amounts 
are possible. 

The next concern comes with a mid week cool off Wednesday morning. 
The latest forecast sees temperatures trending up slightly, however 
some of the lower end guidance brings mid to lower 30s across 
southern portions of the Panhandle. Will continue to keep an eye on 
temperature trends over the next several days, as temperatures in 
the mid to lower 30s could cause some late season frost concerns 
across the southern Panhandle. At this time, the chances seem 
somewhat limited, but again, will be worth keeping a close eye on. 

Mid week through the end of the week, the upper level pattern 
remains fairly active. A series of shortwave and upper level lows 
persist across the Northern Plains, with variations in the placement 
of surface systems and associated rainfall. Precipitation chances 
remain through the end of the week, however, it is a bit difficult 
to nail down a precise timing right now. Certainly, the synoptic 
forcing will be there, so it will also be worth keeping an eye on 
how the upper level pattern evolves over the next several days to 
more precisely time precipitation chances through the week. For now, 
will continue to stick with general chances of showers and 
thunderstorms through the week, however, follow on forecasts may be 
able to refine the timing as models resolve the pattern later this 
week.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 102 AM CDT Sun May 19 2024

The main aviation concern will be the development of rain and 
thunderstorms during the day on Sunday. Confidence remains low on 
timing and location, but at this time the best chance to see 
thunderstorms will be in the afternoon mainly across southwest 
Nebraska and into the Sandhills. Large hail and strong gusts will be 
the main threats as well as reductions in visibility due to intense 
falling rain. The strongest storms should remain south of KVTN. 

&&

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

&&

$$

SYNOPSIS...Richie
SHORT TERM...Richie
LONG TERM...Richie
AVIATION...Kulik