Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/03/23

Area Forecast Discussion

National Weather Service North Platte NE

 512 PM CST Thu Feb 2 2023

...Aviation discussion...

.SYNOPSIS...
Issued at 339 PM CST Thu Feb 2 2023

A large upper ridge sits atop the West Coast today, while a trough
encompasses most of central and eastern US, including an extra dig
toward the Rio Grande Valley. At the surface, a cold front backed
into the Sandhills and is currently (as of 21z) stretching from near
KCDR to KIML. An area of stratus along with a few flurries were
following the front. A high pressure is also filling in behind the
front, but is centered near the Dakotas.

Key points:

- Fog is possible overnight into Friday morning, mainly for western
and southwest Nebraska.

- Wind chills will drop to around -15 late tonight, mainly for north
central Nebraska.

- Somewhat milder conditions are expected the next several days
  with limited precipitation chances.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 339 PM CST Thu Feb 2 2023

This evening and tonight... The cold front is progged to stall in
the panhandle and CO Plains, then start pushing back east as a warm
front. The forward progress can also be shown by increasing
isentropic upglide across the Sandhills overnight and a moderation
in surface dew points. The warm air advection scheme at H85 is
notable in the far west with 24 hr rises near 5C. The front raises a
few concerns, mostly a gradient in min temps, expanse of cloud
cover, fog development, and wind speeds and chills. For now, went
with a general guidance blend for min temps as the values seemed
reasonable overall. They range from the lower teens in the west to
around or slightly below zero far north central. These values assume
cloud cover reaching the Hwys 83 or 183 corridors, while partly
clear conditions remain to the east. Also expanded the fog mention
across the west and attempted to follow the timing of the fropa and
edge of the stratus. Elevated wind speeds (around 10-15 mph) may
limit the threat of widespread dense fog, but it cannot be ruled out
near the stratus edge in southwest Neb. Checked for the potential
for precip near the front. Despite decent forcing in the low levels,
any moisture seems to be very shallow per forecast soundings.
Fog/and or stratus seem to be the better bet. Southerly winds
increase further ahead of the front, especially in north central
Neb. When combined with near zero temps, wind chill values may
approach -15.

Tomorrow... The warm front should push through most of the forecast
area by early evening, while the Western US upper ridge begins to
spread onto the High Plains. Good agreement exists amongst the
02/12z and 02/18z model suites regarding the strengthening WAA and
downslope westerly flow. H85 temps should reach 8C across the
panhandle and Sandhills. Depending on the rate of clearing for the
clouds and fog, along with some mixing, highs may be the mildest in
several days. Clearing should occur during the mid/late morning in
the west and early/mid afternoon in the east. Forecast max temps
reflect this difference with values ranging from the mid 40s
(panhandle) to around 30F (far north central). Trended toward the
MET/ECS for highs, especially in the west, which generally sit near
the top end of the NBM envelope. MAV is the warmest of all and
suggests lower 50s where sunshine exists. Felt that was too
optimistic given the existing snow pack. Downslope flow continues
through the nighttime hours, and H85 temps hold steady with a
thermal ridge and just ahead of an approaching trough. Increasing
cloud cover, a light westerly breeze, and H85 temps near 10C should
combine for relatively mild lows in the upper teens to mid 20s.

.LONG TERM...(Saturday through Thursday)
Issued at 339 PM CST Thu Feb 2 2023

The upper ridge broadens over the Great Plains this weekend and
briefly rebuilds before getting pushed to the East Coast early next
week. Starting Monday, the northern stream dives into the Upper
Midwest while a closed low develops in the southern Plains.
Discrepancies in the long range solutions grow quite a bit with the
placement and timing of the low, but a couple cold fronts should
cross Nebraska nonetheless. Precip potential appears small overall,
but the first cool front on Monday corresponds with a stout mid-
level shortwave. Some light snow or wintry mix will be possible in
Northwest Neb, mainly along the Pine Ridge. The ejection of the
closed upper low onto the Plains midweek will bear watching. Current
indications take the bulk of the moisture just east of the forecast
area, but a westward trek could result in wintry impacts here.
Temperature-wise, highs should maintain near climo (upper 30s to mid
40s) during this stretch. Current forecast lows (in the 20s) may be
a touch warm, depending on continued snow pack, anticipated sky and
wind, etc.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 512 PM CST Thu Feb 2 2023

IFR/LIFR conditions expected at TAF sites overnight.

Late afternoon satellite imagery shows that a north to south
band of low clouds associated with a weak front has drifted just
west of TAF sites. The front will push back eastward through the
region tonight, allowing low clouds and fog to bloom after sunset.

Timing is somewhat uncertain but generally expect IFR CIGs to
develop at KLBF around 02Z then continue to LIFR CIG/VSBY after
Midnight, followed by improvement to VFR conditions Friday
morning. KVTN will see CIGs trend to MVFR after sunset, then to
IFR by Midnight though the lowest visibilities look to remain just
east of the airfield. KVTN is also expected to regain VFR flight
conditions Friday morning. Some rime icing is possible on
aircraft surfaces where fog becomes dense.

Winds will gradually veer around to the southwest through Friday
afternoon with a gradual increase to around 10kt. While little
impact to aircraft operations is expected, winds aloft may
increase to around 25kt with more of a southwest to westerly
direction not far above the surface later tonight.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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