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

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FXUS63 KEAX 231144

National Weather Service Kansas City/Pleasant Hill MO
544 AM CST Thu Feb 23 2017

Issued at 416 AM CST THU FEB 23 2017

A stalled frontal boundary currently draped across central Missouri
will act as the primary forcing mechanism for rain showers and
isolated thunderstorms throughout the day. A negatively tilted upper-
level trough situated over the central Rockies will expand and
approach the Missouri River Valley beginning today through Friday. A
lee-side surface low over western Kansas will continue to strengthen
by this afternoon and eventually lift the stalled frontal
boundary north as a warm front by Thursday afternoon. Isentropic
ascent ahead of this boundary has formed a band of rain showers
across central Kansas as of early Thursday morning. While this
activity is expected to shift eastward into eastern Kansas and
western Missouri by the mid-morning, dry air north of the frontal
boundary may present at least some difficulty for precip to reach
the surface until this afternoon as the boundary continues to
shift north. Better chances of rain, along with isolated
thunderstorms, will arrive later this afternoon as the main upper
wave draws closer to the forecast area. The favored regions for
precipitation will remain north of the warm front, generally for
areas north of the I-70 corridor. Steep mid-level lapse rates
combined with 500 to 1000 J/kg of elevated instability and
abundant deep layer shear will provide support for updrafts
capable of producing up to marginally severe hail this afternoon
for areas north of Highway 36. While chances of precipitation will
persist into the overnight hours for this area, elevated
thunderstorm chances will transition to rain showers by late
Friday evening. With that said, extensive cloud cover and ongoing
rain chances early Friday will limit the full potential of
thunderstorm development, though elevated strong to marginally
severe storms are possible beginning Friday afternoon for this
area. As the surface low further strengthens and advances
eastward, additional precip in the form of light snow, will
affect areas generally north of Highway 50 late Friday night into
Saturday morning as the thermal profile rapidly cools in the wake
of the upper wave. Have increased snow totals slightly for
northern Missouri as a result of a more southern track of the
surface low, though still thinking only minor accumulations are
possible for areas near and north of Highway 36.

A sharp thermal gradient will establish this afternoon, north and
south of the warm front. Temperatures north of the Missouri River
will not rise much more than current observations, peaking into the
mid 50s to lower 60s by this afternoon. Warm temperatures will
persist further south, rising into the upper 70s. A much cooler air
mass will overtake the entire forecast area by this weekend, with
temperatures returning to near-seasonal until early next week. Still
anticipating additional precipitation by Sunday as another system
approaches the area, with an upper wave taking on a more southern
track compared to the one expected today. With cold temperatures
remaining in place aloft, could see another brief round of wintry
precipitation with this system early Sunday, before transitioning
to liquid rain by the afternoon. Surface temperatures will
fluctuate slightly next week, though generally will remain much
cooler than recent trends.


.Aviation...(For the 12Z TAFS through 12Z Friday Morning)
Issued at 526 AM CST THU FEB 23 2017

IFR ceilings will approach STJ early this morning before lifting
back to the north by the mid-morning hours. VFR conditions will
gradually degrade through the early period as as low level
moisture increases ahead of a warm front expected to lift north
this afternoon. While precipitation and perhaps isolated
thunderstorms are favored for areas north of the terminals, with
the exception being STJ, cannot rule out areas of precipitation
for the remaining sites, depending on the northward extent of the
frontal boundary. May see brief clearing in the dry slot of the
storm system this evening before stratus returns along the wrap
around region of the northeastward progressing surface low early
Friday morning. A cold front will turn winds out of the northwest
during this time with stratus lingering through much of Friday.


.Fire Weather...
Issued at 1141 AM CST WED FEB 22 2017

A narrow corridor of very dry and breezy conditions will exist
along and just ahead of a southeastward-moving "cold" front this
afternoon. RHs are expected to drop below 25-30% as temperatures
warm this afternoon, and may be coincident with winds in excess of
20 mph for a 1-2 hour period before winds lessen again with the
arrival of the weak front. Red Flag criteria may be briefly
reached in this corridor, which is currently positioned over
northwest MO and will progress southeastward toward the KC metro
over the next 1-3 hours. Burning is highly discouraged even as
winds diminish this afternoon and evening, due to very low fuel
moisture and the dry low-level atmosphere.




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