Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/23/20
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
600 PM CST Sat Feb 22 2020
.SHORT TERM...(This evening through Sunday)
Issued at 241 PM CST Sat Feb 22 2020
Aloft: It`s the same story as has been the case almost this
entire winter. Fairly low-amplitude zonal flow is over the CONUS.
RAP tropopause analyses and aircraft wind obs revealed a broad
ridge over the Cntrl/Srn Plns. A wk shrtwv trof was over the
Dakota`s and was of no consequence here. Elsewhere...another wk
shrtwv trof was over SW Canada...and a low was over Srn CA. The SW
Canada trof will head E thru Srn Canada. The CA low will move to
the 4-corners by 12Z/Sun and to the OK panhandle by 00Z/Mon. The
ridge will move downstream as a result...with SW flow developing
Surface: 1032 mb high pres was over the Gulf Coast states. That
high will slowly slide into the Atlc thru tomorrow. Meanwhile...
low pres will form and move E thru Srn Canada. A sfc trof will
form to its S with its tail end crossing the CWA late tonight.
High pres will form over the Nrn Rckys behind this trof and low
and will slide into the Nrn Plns tomorrow. Low pres will also be
forming over the Srn Plns.
Rest of this afternoon: Temps have certainly overachieved...with
Areas W of Hwy 183 over S-cntrl NEB have been flirting with near
critical fire wx conds. 5-min obs indicate that the gustiness near
25 mph is just occasional and not continuous. So decided not to
include mention in the HWO.
Tonight: Cirrostratus will cont to stream into the CWA from the
SW mainly S of I-80...but it should overtake the entire CWA after
06Z. So bottom line is incrsg clds.
Low temps are not easy...offsetting incrsg clds with winds
becoming lgt/vrbl in a very dry which will support temps
plummeting after sunset. Am concerned fcst lows may not be cold
enough from I-80 N.
Sun: Partly-mostly cldy forenoon. Becoming cldy after 18Z. It
will take time...but some -RA should move into N-cntrl KS after
18Z. It will be fighting very dry air in place...and dry low-lvl
air continuing to advect in from the NE. Have POPs as far N as Hwy
6...just in case some sprinkles occur...but don`t bet on it.
Am surprised how warm temp guidance is given the thick cld cover
fcst to be overhead. Highs are fcst in the low-mid 50s...but would
not be surprised to see temps fall short of that...espcly S of
Hwy 6 where cld cover will be thickest.
.LONG TERM...(Sunday night through Saturday)
Issued at 241 PM CST Sat Feb 22 2020
Aloft: The longwaves are fcst to amplify next week and spaghetti
plots of the last 2 runs of the GFS-FV3/EC/CMC/UKMET at 500 mb
show indicate exceptionally good agreement all the way thru Fri
Feb 28th. A shrtwv trof currently over the GlfAK will strengthen
and dig into the Nrn Rckys Sun night and cont digging into the
Nrn/Cntrl Plns Mon-Tue...in response to upstream amplification
over the N Pac. This will result in a low forming and moving into
NEB Mon night. It will move downstream into the MS Vly Tue-Wed
along with the longwave trof...and into the Ern USA Thu-Fri.
Cyclonic NW flow will be over NEB/KS Wed-Fri...with the upstream
ridge over Wrn USA/Can. The EC ensemble mean suggests the flow
will deamplify Sat with the dampening Wrn ridge approaching the
Surface: The Srn Plns low will move E into the mid MS Vly Mon.
The next low coming in from the Pac will reform over the Nrn Rckys
Sun with its associated cool front crossing the CWA Mon night.
Strengthening chilly high pres will slide SE out of Canada Tue and
cross the CWA Wed. A warm front is then fcst to form Thu from
cntrl Canada into the Cntrl Plns and become stationary as it will
be parallel to the flow aloft.
Temps: Warmer than normal Mon...then turning cooler than normal
Tue-Wed with widespread highs in the 30s. A warming trend will
dvlp Thu-Sat...and temps could be creeping into the 50s/60s by
Precip: The chance of -RA will cont Sun night...mainly over
N-cntrl KS. But we do have POPs as far N as Hwy 6 just in case. As
the temp profile cools Sun night... what -RA is falling could mix
with or change to snow before ending Mon morning. The upr low
moving in Mon night into Tue will increase instability a bit. That
will result in shwry wx...starting with rain shwr potential Mon
afternoon N and W of the Tri-Cities...then expanding to the entire
CWA during the evening and transitioning to snow shwrs Mon night
into Tue. Pcpn amts are fcst to be light. So little or no accum is
Winds: neglected to mention with the 2016Z update to this product
that winds were incrsd above NBM for Mon and Tue. Mon is looking
breezy. Tue is looking windy. Both the GFS and EC have 40 kt at
850 mb. If that remains the case over the coming couple days...
winds will need to be incrsd further in the fcst...and this will
need to be added to the HWO.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 538 PM CST Sat Feb 22 2020
VFR conditions will continue throughout the TAF valid period through
at least 00Z Monday. Clear skies will give way to high clouds as
we head through the late night hours. Mid to high level clouds are
expected throughout the day on Sunday. The wind will gradually
shift from west northwest this evening, to northerly Sunday
morning, and eventually northeasterly by Sunday afternoon.