Scientific Forecaster Discussion
fxus64 ktsa 211146
Area forecast discussion
National Weather Service Tulsa OK
646 am CDT Sat Oct 21 2017
concerning taf sites ktul/krvs/kbvo/kmlc/kxna/kfyv/kfsm/krog.
MVFR ceilings and breezy southerly winds across much of the County Warning Area during
the morning hours are expected to lift back to just within the
VFR category this afternoon ahead of a cold front approaching the
County Warning Area. Thunderstorms are expected to develop along the front late
this afternoon and spread across the County Warning Area this evening and tonight.
Periods of IFR/MVFR conditions and strong variable winds will be
possible within the stronger storms along/near the leading line
with MVFR conditions...northwesterly winds and decreasing
thunder/rain chances behind the front. Will carry tempo groups for
timing of the stronger storms. Conditions look to begin lifting
back to VFR/clearing out across northeast Oklahoma late in the taf
Previous discussion... /issued 320 am CDT Sat Oct 21 2017/
The main items of interest for this morning's forecast will be
severe storm and heavy rain potential late today and tonight with
a cold front, and rain chances/temps with a strong front late next
Broad western Continental U.S. Trough is marching toward the plains this
morning. A pocket of higher pv was located near The Four Corners
near the basal portion of the parent trough. This energy will move
out into the central/Southern Plains later today and will help
provide lift along with the associated Pacific front to produce
widespread storms across the region thru tonight.
The latest short term hi-res guidance indicates some semi-discrete
cell development between 21z and 00z to the west/northwest of
Tulsa, where the greatest threat for hail will be with this event.
An isolated tornado is possible as well. Storms should quickly
grow upscale into a squall line by the time they reach Tulsa and
will continue to March south and east from there thru the night.
Some hi-res guidance indicates there will be potential for some
qlcs tornadoes where segments of the line can Bow out to the east
and northeast. This threat will be greatest to the west of Highway
69 in northeast Oklahoma. It will be interesting to see how the
supercells that are expected to develop across central OK evolve,
because as they become a portion of the eventual squall line,
they could bring the best threat for qlcs tornadoes as the system
moves into northeast OK. The line should generally decrease in
intensity as it moves into Arkansas and southeast Oklahoma owing
to decreasing instability after midnight.
Given the progressive nature of the system, the flash flood threat
will be localized at best. However, broad 1 to 2 inch rains over
the region may cause a few river points to flood.
There will be a temperature roller coaster next week with
primarily tranquil weather. After a mild start to the work week
Monday, cooler temps are expected Tuesday behind a polar cold
front which will push thru Monday night. Another quick warm-up is
expected thru Thursday ahead of the next system.
There is a lot of uncertainty regarding the evolution of the upper
flow pattern late next week and into the weekend. One thing is
fairly certain. Some shortwave energy is expected to dive
southeast across the middle of the country late next week and will
force another strong polar cold front thru the region. The
Canadian and GFS keep this system a progressive open wave and
suggest little in the way of precip for the area. The 00z European model (ecmwf) is
following in the footsteps of the 12z run, closing the system off
well to our west and is much wetter going into next weekend. Given
the uncertainty, will keep the chance pops from the consensus
guidance for Friday with the front, and will maintain low pops
going into the weekend. The temperature forecast is no walk in the
park either during this time frame. Started with consensus
forecast and made adjustments.
Preliminary point temps/pops...
tul 79 52 71 44 / 30 100 10 0
fsm 78 59 70 46 / 20 100 40 10
mlc 80 55 70 43 / 20 100 10 0
bvo 77 50 72 38 / 60 100 10 0
fyv 74 54 64 38 / 20 100 30 10
byv 74 55 65 44 / 20 100 40 10
mko 79 53 69 44 / 20 100 20 0
Mio 77 51 68 43 / 10 100 20 0
f10 79 53 70 45 / 20 100 10 0
hhw 82 58 71 47 / 20 100 30 10