Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 030841

341 AM CDT Wed Jun 3 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CDT Wed Jun 3 2015

Primary forecast question for today is how far southeast the MCS
over Nebraska will get.  Short range guidance suggests that the bulk
of the precip will stay out of our central/northeast MO counties
today as it should hit a wall of dry and stable air.  That being
said, the southern end of the MCS still looks pretty impressive and
the 850mb low level jet should continue to pump moisture into
western Missouri through the morning.  Wouldn`t be surprised to see
some of the last gasps of the MCS dribble into our far western
counties before noon so have continued the slight chance/low chance
PoPs for today over those areas.  Rest of the area looks to remain
dry with temperatures finally getting to near or even slightly above


.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 252 PM CDT Tue Jun 2 2015

The expansive lower troposheric anticyclone that has help maintained
the low clouds the last 3-4 days will continue to weaken and depart
east with winds veering to southeast-southerly on Wed. I suspect
we will have more diurnal cu again on Wednesday, probably not as
extensive as today, but enough for me to trim the high temps back
a few degrees from the previous forecast. While I am not overly
excited about the prospect, there is a slight chance of seeing
some showers or thunderstorms in parts of north-central/northeast
MO along the tail end of a weak impulse aloft and where there is
growing low-level WAA and moisture transport on the eastern
periphery of the return flow. The areal extent of the shower and
thunderstorm threat will increase across the northeast third of
the CWA Wednesday night due to improving low-level WAA/moisture
and potential for maintenance of any showers and storms moving
southeastward out of Iowa.

Overall the pattern will become warmer and much more active
Thursday into early next week with the possibility of multiple
organized thunderstorm episodes/MCSs and a nearly continuous
thunderstorm threat depending on your location. As has been
alluded to the last several days, while ridging aloft will be
building through the Plains and attempting to build into parts of
the MS Valley, short-waves will be topping the ridge crest and
moving east and southeast impacting the area. The most prominent
threat appears to be late Thursday into Friday when several of
these impulses will impact the region and an east-west front will
drop southward interacting with an increasingly warm, moist and
unstable air mass. There may be a lull on Saturday depending on
the exact location of the front. It is expected to pass through
the CWA but then waver and return northward Saturday night with
yet another front pushing into the area Sunday/Sunday night as
upper troffing becomes established across the northeast quarter of
the CONUS.



.AVIATION:  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1140 PM CDT Tue Jun 2 2015

Combination of advection and dissipation has confined the late
evening MVFR SC deck to SE MO/SW IL...with the e edge of the cloud
deck over SW IL still showing a very definite wwd push over the
last few hours. I`ve kept some 3kft cloudiness floating around in
most locations during the predawn hours, but based on latest
satellite trends have not gone with any MVFR cigs at any
locations. However, based on late evening T/Td spreads I did
include a mention of fog at both SUS and CPS as well as COU for
late tonight into early Wednesday, with lowest IFR vsbys at fog-
prone SUS. Still believe we should see some CU pop as the
inversion breaks Wednesday morning, and although I`ve only
indicated scattered clouds it`s certainly possible that this could
produce a brief MVFR cig before mixing raises cloud bases aoa 3kft
and diminishes the cloud deck. I`ve also brought in some mid
clouds to our western areas tomorrow afternoon/evening, but have
omitted mention of precip at this time given uncertainty in timing/coverage.

Specifics for KSTL: Based on latest satellite trends have gone
with just a few SC clouds around 3kft during the predawn hours,
followed by the development of CU as inversion breaks Wednesday
morning. The base of this developing cloud deck should be around
2kft, but they will easily increase to aoa 3kft no later than
midday as mixing increases/deepens over the area.



Saint Louis     81  65  84  69 /  10   5  10  20
Quincy          79  63  82  66 /  20  20  40  50
Columbia        79  64  84  67 /  20  20  20  30
Jefferson City  81  64  85  67 /  20  20  20  30
Salem           78  61  83  66 /   5   0   5  10
Farmington      79  57  82  63 /  10   0   5  10




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