Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 022027
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
327 PM CDT Tue Jun 2 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 300 PM CDT Tue Jun 2 2015

The pesky stratus/stratocu remains the biggest issue tonight. In
the areas which have clouds that are more cumuliform in nature
such as St. Louis north and east, the clouds should dissipate this
evening with loss of heating. However for areas further south and
west, the clouds will be slower to dissolve, if at all completely.
Considering trends the last few days I have been rather pessimistic
and it would not surprise me at all if there are pockets/bands of
stratus aligned with the low level southeasterly flow at daybreak
on Wednesday.

Glass

.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.

Glass

&&

.AVIATION:  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1236 PM CDT Tue Jun 2 2015

SCT to BKN low end VFR thru this afternoon. Winds will remain ely
to sely this afternoon, becoming light tonight, then picking up
Wed morning from the SE again remaining aob 10 kts thru the TAF
period. Can not rule out light FG development late tonight at UIN
and COU. However, believe mixing will persist thru tonight
preventing FG development.

Tilly

&&

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

$$

WFO LSX






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