Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 260536

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1136 PM CST Sat Feb 25 2017

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 324 PM CST Sat Feb 25 2017

High pressure centered over eastern Oklahoma will move east through
the Mississippi Valley tonight and into the southeast CONUS on
Sunday.  The ridge axis will pass east of the CWFA after 06Z tonight
which will cause the wind to swing back around to the south.  Wind
should drop off pretty quickly later this afternoon and this evening
as the ridge axis moves closer.  Light wind, mostly clear sky, and a
cold airmass over the area should yield quickly falling temperatures
due to radiational cooling this evening.  Think temperatures will
bottom out in the mid and upper 20s across the area by 06-08z, and
then remain nearly steady thereafter as southerly flow develops and
strengthens toward sunrise.  Increasing clouds moving in from the
west-southwest will also help to shut off the radiational cooling
late tonight.

Southwest flow at 850mb will increase to around 40kts over eastern
Texas and Arkansas on Sunday which will produce moderate warm
advection over parts of central and southern Missouri.  However, the
strongest baroclinicity sets up over the Ozarks along the
Missouri/Arkansas border.  The QPF generated by the models looks a
little far north across central and eastern Missouri into southwest
Illinois Sunday afternoon compared to where the best forcing will
be, and guidance PoPs are lower than what the previous forecast was
showing. Went ahead and lowered PoPs for Sunday afternoon in this
package to go closer to what guidance is showing.  Temperatures
should warm back up into the mid 40s to around 50 due to the
southerly flow.


.LONG TERM...  (Sunday Night through Next Saturday)
Issued at 324 PM CST Sat Feb 25 2017

A rather active pattern will take shape from  Monday night through
midweek. The period starts with a fast quasi zone flow over the area
coupled with southernly flow at the surface will bring temperatures
above seasonal normals. A cold front approaches from the west
Tuesday morning. This will bring windy and warm conditions to the
area along with a chance of thunderstorms with the fast moving
frontal system. There is roughly six hour difference in timing with
the GFS vs ECMWF. The GFS is six hours faster than the ECMWF.  The
cold front should clear the region by midday Wednesday either way.

High pressure will filter slightly cooler and drier air to the
area along with temperatures closer to seasonal norms through
early next weekend. There could be a spot shower or two on
thursday afternoon in NE MO and WC IL as a stationary boundary
approaches the area from the north. A couple of flurries are also
possible late thursday night into Friday morning over parts of WC



.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1131 PM CST Sat Feb 25 2017

VFR and dry thru the period. Clear sky will gradually fill with
clouds with cigs lowering Sun morning thru the afternoon. Expect
any precip to remain south of the terminals. Can not completely
rule out a brief sprinkle with lower cigs, but this seems unlikely
attm. Sfc ridge continues to build ewd overnight with winds
becoming sly to swly with gusts during the late morning and into
afternoon hours.





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