Scientific Forecaster Discussion
fxus63 ksgf 231703
Area forecast discussion
National Weather Service Springfield MO
1203 PM CDT Tue may 23 2017
Short term...(today and tonight)
issued at 148 am CDT Tue may 23 2017
A sfc cold front extends for central Iowa into eastern Kansas. This
front will move quickly east reaching the eastern cwfa border by
early afternoon. Showers have been spotty ahead of the front with
limited moisture return. An uptick in moisture ahead of the front
is expected, so expect coverage of the showers to increase this
morning. Modest instability will support some spotty lighting,
but not much more. Nice to have some rain that doesn't arrive by
the bucketful for a change.
With the clouds and the frontal passage, temperatures will be
chilly for this time of year behind front.
An upper low over centered over the Midwest will move south into
northeast MO by 12z/7am Wed. Post frontal clouds should be fairly
abundant. Can't rule out some breaks at times.
Long term...(wednesday through monday)
issued at 245 am CDT Tue may 23 2017
The weather looks to become more active to end the week.
Wednesday: the closed upper low over MO will move SSE into Tennessee by
Wed night. Cold air aloft will support some additional
clouds/light showers especially with some modest diurnally driven
afternoon instability. Best chances look to be the eastern cwfa.
Again, not looking at anything high impact. It will be another
unseasonably cool day.
Thursday: a warming trend is expected as the upper low shifts off
to the east and sfc winds back to the west and southwest. High
temperatures will rebound back up to near normal (mid/upper 70s)
after a chilly morning start.
Thursday night-friday: the upper level pattern shifts during this
time frame with a split flow pattern over the Continental U.S.. we will be
more influenced by a subtropical jet Fri-Sat. Lee side sfc low
pressure is expected to develop over the High Plains Wed-Thu,
gradually consolidating into a sfc low over the Texas Panhandle by
Thu evening. Gulf moisture will shift back to the north, with the
best moisture advection initially over the plains just to our west
Thu night. An elevated mixed layer (eml) will overspread the warm
sector (including our area) during this time. Couldn't rule out
some elevated convection late Thu night into Fri morning with an
increasing low level jet, as the sfc low moves east into central
OK. By and large, the capping underneath the eml will limit rain
chances through Friday despite strong instability.
Late Friday afternoon-Saturday. An approaching shortwave and a
sfc wave along a sfc front just to our west will increase
rain/thunderstorm chances during this time. Capping is expected to
temporarily weaken toward evening Friday with lowering mid level
heights (cooling) and daytime heating. An increased nighttime low
level jet will aid in lift, but progged GFS soundings do not have
much moisture above 850mb, so again, overall coverage of rainfall
may be fairly limited. Any surfaced based convection that could
theoretically break the cap would be robust given the instability
and strong mid level lapse rates. Saturday may be the most active
day as the sfc front/frontal wave move through out cwfa. Weakly
capped strong instability should allow convection to develop with
the front's passage. MLCAPE could be on order of 4000 j/kg Sat
with winds/large hail the main potential hazards. We will need to
watch how guidance evolves for this time period. Still some
uncertainty with the timing of the front and possible mesoscale
influences not resolved by global models this far out in time.
Sunday-Memorial Day monday: looks like a period of relative quiet
behind the front as the northern branch of the upper level flow
helps bring in drier air. Hopefully this timing will hold.
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1200 PM CDT Tue may 23 2017
The front has pushed through the area this morning. We are still
expecting scattered or widely scattered showers during the
afternoon, more prevalent across the Eastern Ozarks. Ceilings
during the afternoon hours should improve into VFR. Upper low will
dive south into the area late tonight and will see ceilings dip
back into MVFR and potentially IFR as we get towards sunrise.