Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 221057
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
557 AM CDT Fri May 22 2015
Issued at 307 AM CDT FRI MAY 22 2015
Large upper trough over the western U.S. will bring quite a bit of
wet weather to our area over the holiday weekend as it slowly moves
eastward. First round of precipitation could affect areas near and
south of the KC area as early as this afternoon, though this activity
will be encountering low-level ridging and some dry low-level air by
the time it makes it this far east. Therefore anything that falls
today or tonight should be fairly light and scattered in nature, and
shouldn`t be enough to really spoil outdoor activities.
More widespread rain and thunderstorms will begin moving into the
area on Saturday and really pick up in coverage and intensity
Saturday night and Sunday. Persistent 30-40 kt LLJ through this
period will transport increasing moisture with precipitable water
values reaching the 1.5" to 1.8" range Saturday night. This moisture
combined with steady isentropic ascent and broad synoptic ascent
ahead of the main upper wave will favor several round of rain and
thunderstorms Saturday night into Sunday evening. Instability will be
weak and not too favorable for strong storms or torrential downpours,
although magnitude of moisture transport and warm cloud depth
alone could favor some areas of heavy rain. Additionally, with
southerly flow all the way from the surface to the tropopause, some
lines of training storms could develop capable of dropping localized
rainfall amounts of 1" to 2" or even higher particularly across areas
near the KS/MO state line.
Things will become somewhat drier by Monday as the primary upper
trough axis swings through and allows warmer air to build into the
region. This however will allow the atmosphere to become quite a bit
more unstable which could cause scattered storms to develop during
the afternoon. Wind shear will be fairly weak but couldn`t rule out a
few stronger storms if the airmass can become moderately to strongly
unstable as the GFS suggests.
Broad southwest upper flow will continue for much of next week.
Combination of an unstable airmass and random perturbations in the
upper flow could spark scattered storms any day next week. Shear will
be weak so the threat for any organized severe storms or widespread
heavy rain looks low.
.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 556 AM CDT FRI MAY 22 2015
Large area of rain over KS and OK will weaken significantly by the
time it gets this far east later today. Other than a few isolated
showers or sprinkles this afternoon, most of the day should be dry.
Slightly better chances for scattered showers will arrive late
tonight. Overall wind pattern will be to go from southwesterly to
southeasterly through the day, although they could vary quite a bit
occasionally due to the light nature.