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000
FXUS63 KLSX 191117
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
617 AM CDT Sat Apr 19 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 310 AM CDT Sat Apr 19 2014

Mostly sunny skies and warming temperatures are on tap across the
area as we start the weekend. As the surface ridge continues to
move slowly southeast, winds will veer to the south today, and
temperatures should easily climb to the low to middle 70s across
the forecast area. Warmest temperatures, approaching the upper
70s, are expected over mid Missouri and extending eastward along
the Missouri river toward the St. Louis metropolitan area.

JP

.LONG TERM:  (Tonight through Friday)
Issued at 310 AM CDT Sat Apr 19 2014

Southerly return flow will continue across the forecast area
through Sunday as an upper level ridge builds from east central
Texas, its axis extending through Missouri and toward the Great
Lakes. The ridge will begin to shift eastward Sunday afternoon,
with Sunday remaining dry, but with increasing cloudiness ahead of
a few shortwaves progged to impact the forecast area beginning
Sunday night. Models have once again slowed down the onset of
precipitation over the forecast area Sunday night, with
precipitation expected to develop over extreme western Missouri
around 00Z, and enter mid Missouri by around 06Z. Currently expect
a bulk of the precipitation to occur over our area during the day
on Monday, in the form of showers with a few thunderstorms, when a
shallow mid-level trough and accompanying cold front move eastward
through the middle Mississippi Valley. Precipitation is
anticipated to gradually come to an end on Monday night, with the
front southeast of the area by 12Z Tuesday. While models are in
agreement with high pressure building into the region in the wake
of the cold front, the GFS is most aggressive with cooler
temperatures Tuesday, whereas the ECMWF and SREF output indicate
temperatures moderating to near normal.

Beyond Tuesday, not many changes have been made to the extended,
as models continue to indicate the development and amplification
of another ridge, in the wake of a departing and deepening trough
over the eastern CONUS, and another deepening trough over the
inter-mountain West. Wednesday and Wednesday night, the ECMWF
continues to indicate the potential for ridge-runner type
precipitation, mainly affecting the northern half of the county
warning area, though the main chance for precipitation in the
extended remains associated with an intensifying low pressure
system over the northern plains. There continues to be a
discrepancy in timing of this feature and its accompanying cold
front, which will impact our area some time during
Thursday/Thursday night time frame. Both the ECMWF and GFS
indicate a potential line of thunderstorms, though the ECMWF still
remains about 6 hours faster than the GFS with this feature.
Despite any timing differences, Friday will be cooler across the
area as northwest flow and high pressure build into the region
behind the front as the low lifts toward the Great Lakes.

JP

&&

.AVIATION:  (For the 12z TAFs through 12z Sunday Morning)
Issued at 611 AM CDT Sat Apr 19 2014

Surface ridge axis extending from the southern Lake Michigan
southwest through the Boot Heel of Missouri into Arkansas will
continue to drift eastward today. East wind will veer to the
south-southeast today as this occurs. VFR flight conditions will
continue to prevail.

Specifics for KSTL:

Surface ridge axis now east of the terminal will continue to move
east today. This will cause the wind to veer to the southeast by
mid-late this morning. VFR flight conditions will continue to prevail.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX