Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 180525
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1225 AM CDT Thu May 18 2017

.Discussion...
Issued at 139 PM CDT WED MAY 17 2017

A strong, negatively-tilted upper-level trough will continue to
mature and lift northeast into southern Iowa through the remainder
of the afternoon. Convection has developed over north central to
northeastern Kansas underneath the upper low, with new convection
initiating just ahead of the circulation, where rapid clearing
through the late morning has destabilized the environment
underneath a highly sheared environment. This activity will
continue to develop ahead of the storm system and advance into
western Missouri by the early to mid-afternoon. Strong upper-
level dynamics has resulted in bulk shear values of 50 to 70 kts.
This, coupled with MLCAPE values of 1000 to 1500 J/kg will favor
rotating updrafts through the duration of the event. Cannot rule
out a few tornadoes, near locations where surface winds are
backed, particularly over areas closer to the surface low across
northwest Missouri. Given the highly sheared environment, deep
convection may be difficult to establish, thus at least partially
mitigating the hail threat, though large hail remains possible
within any rotating thunderstorms. The primary hazard will reside
with strong to damaging winds given the deep mixing trends and
surface winds already near severe criteria. The progressive nature
of the system as a whole will quickly push storms out of the
local area by the late afternoon/early evening. Gusty surface
winds will then slowly taper off after sunset.

Southwest flow will resume overnight until a warm front lifts north
across central Missouri Thursday morning. While Thursday will remain
mostly dry, moisture return south of the frontal boundary may bring
the next chance of afternoon thunderstorms for the southern CWA. A
few strong storms are possible with any storms which may develop,
though moisture will remain rather limited until Thursday evening
into the overnight. At that time, a broad upper-level low will eject
several impulses overhead the stalled frontal boundary, coincident
with greater moisture return from the Gulf of Mexico. As the upper
level system weakens while lifting northeast by Friday, the warm
front will continue to slowly lift into northern Missouri. Thus,
precipitation chances will persist through much of Friday into
Saturday. Will need to monitor hydrologic concerns over west central
Missouri to north central Missouri, given the position of the
stalled frontal boundary over a multi-day precipitation event.
Expecting highest rainfall totals to approach 2 to 3 inches, with
the main period of activity beginning Thursday evening and
persisting through Saturday morning to perhaps afternoon.

A broad surface high will then move into the region by the late
weekend, and will maintain dry conditions briefly. Seasonal to below
seasonal temperatures will be gladly welcomed for much of next week
as cooler air masses advect overhead. Storm chances will return
to the area by the early to mid week, as the active upper level
pattern resumes.

&&

.Aviation...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1225 AM CDT THU MAY 18 2017

VFR conditions and light winds are expected through the majority
of the forecast period; however, a complex of storms is expected
to push eastward across KS and potentially impact all TAF sites
near the end of the period. Have included VCTS at the end of the
forecast and will refine in future issuances.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

Discussion...Welsh
Aviation...Laflin



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