Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 070836
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
336 AM CDT Thu May 7 2015
Issued at 335 AM CDT THU MAY 7 2015
The active weather pattern will persist through the end of the week
and into weekend with each day having some risk for strong to
potentially severe storms at various times.
For today, there is a plethora of potential items that may help to
renew convection within an already moist and unstable atmosphere.
The most evident, at least on the scale models can resolve at this
point, is a weak front moving south into the area this afternoon.
There may also be an outflow boundary or two filter into the area
from the robust convection ongoing to our north and northwest.
Additionally, there may be MCVs floating northward from the intense
convection ongoing in Oklahoma and earlier in Kansas. All these small
scale features make figuring where the best chances for renewed
convection will occur rather difficult. The most likely area though
should be the frontal boundary sliding into northwestern Missouri
this afternoon. Models show moderate to strong instability developing
in far northwestern MO and northeastern KS by the afternoon. Shear
looks to be marginal in this area so the potential for organized
convection seems low. But given the possibility of CAPE in the 2000
to 3000 J/kg range, strong storms would be likely should develop and
a few severe storms can`t be ruled out.
For Friday, that frontal boundary looks to continue to be draped
from southwestern KS through northwestern MO. Moderate to strong
instability should build once again. Shear looks to be stronger than
in previous days as stronger flow aloft begins to move over the
region. With 0-6km shear of 30 to 35 kts occurring over 2000 to 2500
J/kg of CAPE, there will be a better chance for a few severe storms
during the afternoon hours. The most likely area to see this
potential looks to be over the southwestern quadrant of the forecast
Saturday and Sunday continue to look like the best days for more
widespread severe convection. A deep upper level trough will begin
to shift into the Rockies by late Saturday and then into the Plains
on Sunday. As a strong jet streak rotates around the base of the
upper trough, wind shear will increase dramatically over top a very
unstable atmosphere. This will set the stage for severe convection
developing to our west during the afternoon and evening hours. This
activity should congeal into one or more convective systems and track
rapidly to the east/northeast, moving into our western areas late in
the evening or overnight. Given how strong the flow is from the
south, very high precipitable water values will advect into the
region ahead of the convection. Models are in good agreement with the
magnitude of the values but vary some on timing still. But values in
the 1.5" to 1.8" appear likely which is well above the 90th
percentile and close to the maximum values seen for that day based on
sounding climatology. So if the convection isn`t severe as it moves
into our area, it looks to be very efficient with heavy rain and
flooding possible. That convection looks to move away in time for the
atmosphere to again become moderately to strongly unstable by Sunday
afternoon but with the upper wave now into the Plains and its
associated surface low now over eastern Nebraska. The trailing
modified dry line/Pacific front is then poised just to our west in
eastern Kansas. Severe convection is likely to develop along or just
ahead of this front during the afternoon. Shear is very high,
approaching 50 kts. Hodographs however are not very impressive as the
winds are nearly unidirectional. So it looks like there will some
potential for supercells/ supercell structures initially before
storms quickly form into more of a linear system and rapidly track to
the east/northeast into and through the forecast area.
Fortunately, with the passage of this upper trough and its
associated surface fronts, the airmass becomes much more stable with
high pressure building into the region through the middle of the
week. This should result in much quieter weather. While temperatures
will be cooler than normal for Monday and perhaps Tuesday, a return
to more seasonal values will occur by the middle of the week.
.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1134 PM CDT WED MAY 6 2015
Precipitation will be the main factor through the forecast as
multiple waves of activity continue to cross through the area.
Expecting conditions to remain VFR with cloud bases above 10 kft.
Convective activity is possible Thursday afternoon if the clouds
break up enough to develop surface instability, but confidence in
this becoming an issue is low at this point. Gusty southeast winds
will veer slightly before weakening toward the end of the period.