422
FXUS63 KLBF 212016
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
316 PM CDT Sat Sep 21 2024

.KEY MESSAGES...

- Threat for precipitation Tonight into Sunday continues to shift
south.

- Potential for patchy frost Monday morning across portions of
southwestern Nebraska and the Sandhills.

- Dry conditions expected after Tuesday morning next week with
  above normal temps.

&&

.SYNOPSIS...
Issued at 316 PM CDT Sat Sep 21 2024

H5 analysis this morning had a fairly active pattern across the
CONUS. Closed low pressure was located over western Arizona
with a trough extending south into the Gulf of California. East
of this feature, high pressure was anchored over south Texas.
Further north, a trough of low pressure extended from east
central Saskatchewan, south into North Dakota. One last feature
of note was the persistent area of low pressure off of Cape Cod
Massachusetts. A strong cold front blew through the forecast
area earlier this morning. This has led to gusty northerly winds
across western and north central Nebraska this afternoon.
Northerly wind gusts as high as 40 MPH were reported at
Imperial. Skies were mainly clear over north central Nebraska
with partly to mostly cloudy skies central to southwestern
Nebraska. Temperatures as of 2 PM CT ranged from 62 degrees at
Gordon to 73 degrees at Imperial.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 316 PM CDT Sat Sep 21 2024

The main forecast challenges continue to be precipitation
chances tonight into Sunday morning, then the threat for frost
Sunday night into Monday morning. For tonight, the upper level
will emerge from the Four Corners into central Colorado by 12z
Sunday. A broad shield of precipitation will develop from
eastern Colorado into Kansas and far southern Nebraska. This
precipitation will be most pronounced along and north of the
surface cold front, which will reside along a line from the
northern Texas Panhandle into SE Nebraska by 00z Sunday. Further
north, the precipitation picture becomes more problematic.
Already overnight, the latest NBM probabilities for >0.01 inches
of precipitation have trended further south. Overnight, there
is now less than a 50% probability of measurable pcpn, north of
interstate 80. By the time you reach highway 92, that
probability falls off to under 20 percent. The latest EC
ensemble QPF probabilities for >0.01" are very similar to the
NBM forecast having less than a 50 percent chance of measurable
pcpn north of I-80 and less than 25 percent north of highway 92.
This is also supported by the latest GFS and NAM12 isentropic
fields at the 305thete level, which have the greatest lift
generally along and south of highway 23 from Grant to Wellfleet.
That being said, have lowered pops further in the central
forecast area, and tightened up the northern gradient of pops.
For example, across Lincoln county, we go from a 20 pop in the
northern third of the county, to around 50 to 60 percent on the
southern fringes of the county. As for QPF`s, they continue to
trend downward with the latest deterministic solns (HRRR and 3KM
NAM) which has roughly a quarter inch across the southern tier
of counties, falling to near zero around I-80. Isentropic lift
will exit the forecast area during the late morning/early
afternoon hours Sunday, ending the precipitation threat over the
southern quarter of the forecast area. Even with precipitation
exiting the area midday, cloud cover will persist across the
southern third of the forecast area, limiting highs. I did trend
temps up slightly from the inherited forecast based on a more
southerly track of precipitation and additional expected
clearing across central portions of the forecast area. Highs
Sunday will range from the upper 50s in the far south, to the
upper 60s over northern Nebraska. Skies will begin to clear out
Sunday evening. High pressure will build into southwestern
Nebraska Sunday evening, transitioning into northwestern Kansas
overnight. As for lows Sunday night, based on the shift in high
pressure to the south, the coldest temps should be in the Platte
River valley and portions of southwestern into central
Nebraska. This is a shift from the previous forecast which
favored the coldest temps in the western Sandhills. In these
areas, light southerly winds will develop overnight on the
northwestern periphery of the high. No surprise, low temps in
the western Sandhills have trended slightly upward with the
latest statistical guidance. Why is this important? Forecasted
lows reach into the middle 30s Monday morning in the Platte
River valley and portions of SW Nebraska. This may facilitate
the first frost of the fall season. With better than a 50
percent probability of lows < 36F over portions of SW Nebraska
and portions of the western Sandhills. Will be adding a mention
of patchy frost to the grids. As for a frost headline product,
will forgo this for now as forecast confidence in areas of frost
coverage isn`t quite there yet.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 316 PM CDT Sat Sep 21 2024

A weak upper level disturbance will dive south from the Dakotas
into Nebraska Monday night. This may lead to a small threat for
precipitation in western portions of the forecast area. The
inherited forecast as well as the new NBM does have some < 20%
pops in the west and far southwest Monday night. This new NBM
soln has trended farther southwest and lower with its new
forecast. Looking at the latest probabilistic forecast from the
ECMWF, wouldn`t be surprised if pops were eliminated from the
forecast with the next NBM run. Beyond Monday night, a dry
forecast is favored as a cutoff low develops over the southern
plains and high pressure builds into the central and northern
plains. Temperatures will trend back to near normal midweek with
above normal temperatures expected thereafter. The latest NBM
forecast has upper 70s to lower 80s for Wednesday through
Saturday, which is on the order of 5 to 10 degrees above normal
for this time of year. Lows will generally be in the upper 40s
to lower 50s which is slightly above normal for this time of
year.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1245 PM CDT Sat Sep 21 2024

Gusty north to northeast winds will gradually diminish this
afternoon into this evening. Otherwise VFR conditions are
expected to prevail. A storm system will pass to our south
tonight into Sunday. Mostly just mid and high level cloudiness
is expected for our area. However, some light rain is possible,
mainly south of I-80.

&&

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

&&

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...Taylor