Scientific Forecaster Discussion
fxus63 kgid 231937
Area forecast discussion
National Weather Service Hastings NE
237 PM CDT Wed may 23 2018
..isolated svr tstms possible late afternoon-evening hrs today
Short term...(this evening through thursday)
issued at 237 PM CDT Wed may 23 2018
Aloft: rap analyses/WV imagery and 12z raobs show the Rex block
remains over wrn North America. The low was over Idaho/Wyoming with SW flow
over the plns. The Rex block will finally break down over the next
24 hrs...but that does not mean an end to the Summer wx. Models
are tightly clustered on the low drifting into Montana tonight and into
the Canadian prairies tomorrow. As this occurs...the flow will
remain SW over the cntrl plns...but a trailing trof from the low
will move over the plns from ND to wrn Kansas by 00z/Fri.
Surface: the County Warning Area was in the warm sector. Low pres was over Montana
with a warm front extending southeast into the mid-MS Vly. High pres was
over the gtlakes. The rgn will remain in the warm sector thru
tomorrow as the low lifts to lk Winnipeg. As it does so...a
trailing sfc trof will drift from the Lee side of The Rockies into
cntrl neb and northwest Kansas... extending from onl-lxn-cbk.
Now thru mid-evening: isolated tstms. MLCAPE 1500-2000 j/kg but
0-6 km shear is very weak (20 kt). So expect outflow dominant
Tonight: any evening storms will die shortly after sunset with no
help aloft. With no change in the situation...could small/isolated
shwrs and possibly a tstm or two redevelop after 3 am...similar to
this morning. Most locations will remain dry.
A mild and muggy night with dwpts in the 60s. Temps will not fall
below 70f until after midnight.
Thu: possibly similar to this am with small isolated shwrs
associated with high-based altocumulus castellanus. Isolated tstms could develop
along the sfc trof. With temps 87-92f and dwpts in the 60s...
MLCAPE is fcst near 2500 j/kg. 0-6 km shear will be 15-25 kt
across the County Warning Area (lowest east/highest w). Any tstms that develop could
turn svr...but tstm coverage will not be widespread.
Temps similar to today (87-92f).
Long term...(thursday night through wednesday)
issued at 237 PM CDT Wed may 23 2018
Aloft: the last 2 runs of global models and the ec/GFS ensemble
means are in excellent agreement that the westerlies will remain
far to the north over Canada thru next Wed. Low-amplitude northwest flow will
occur Fri behind thu's trof. A ridge will then build over the
cntrl USA Sat downstream of a low that moves into the wrn USA and
cuts off over Utah. Neb/Kansas will be on the west side of the ridge with
weak SW flow. Predictability regarding when cut-off's open up or
become Mobile is low...but present indications are that a trof
approaching the West Coast could force the low to lift into the nrn
rckys Tue and the nrn plns Wed as a remnant trof. The tail end of
this trof could affect the County Warning Area.
Surface: very weak high pres will build over the cntrl plns Fri-
Sat. It is then fcst to drift east of the rgn sun. A large high will
sink from Canada into the gtlakes Mon-Wed. This scenario will
maintain multiple days of return flow.
Temps: the heat is on. Welcome to an early Summer. Widespread
low-mid 90s Fri-Mon...then possibly cooling back into the 80s-low
90s Tue-Wed as heights fall a bit.
Precip: mostly dry. There will be the typical isolated tstms that
fire daily well to the west within the Lee trof. The weak flow and
lack of forcing will keep nearly all of it well to the west of the
County Warning Area...but can't completely rule out a rogue storm or two making it
to areas west of Hwy 183. If the upr trof moves thru here Tue or Wed
that would increase the risk of sct tstms.
Aviation...(for the 18z kgri/kear tafs through 18z thursday)
issued at 126 PM CDT Wed may 23 2018
Significant wx: low level wind shear tonight.
This afternoon: VFR with few-scattered cumulus 5-6k ft. Scattered-broken altocu and
cirrostratus 10k ft and above. S winds 15-25 kt. Confidence: high
Tonight: VFR. No clds at or below 10k ft but there could be a few
VFR -shra's around after 09z with altocu bases 10-12k ft. Low level wind shear
develops. S winds 8-15 kt. Confidence: high
Thu thru 18z: VFR. Few-scattered altocu around 10-12k ft. Still could be
a few -shra's around. Possibly a -tsra. S winds increase to 15-25
kt. Confidence: high