Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 270854
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
354 AM CDT SAT AUG 27 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 353 AM CDT Sat Aug 27 2016

SW upper flow remains in place with a short wave lifting NE form the
nthrn Plains into sthrn Canada. Focus remains on trying to determine
convective trends....though this attempt appears to be futile.
Needless to say the location of highest PoPs is low confidence. The
stalled bndry has finally begun to lift back north over the past
several hours and appears to be aligned roughly along the IA/MO
border and on E across cntrl IL as of early Sat mrng. A weak area of
low pressure moving NE will help lift the front well N of the
CWA by this aftn. This will allow the warm...humid and unstable
airmass confined to sthrn IL and sthrn MO over the past several days
to expand across the entire FA. The lack of a focusing mechanism
means that convection may dvlp just about anywhere at anytime...but
should be concentrated temporally drng the PM hrs.

SPC has the nthrn portion of the CWA in a marginal risk again today.
This is supported by 1000-3000 J/kg of SBCAPE and around 30 kts of
0-6 km bulk shear. Can`t rule out a strong to potentially SVR
storm but modest lapse rates and a moist profile should limit the
SVR threat. The heavy rain threat may be a bigger factor once
again due to PWATs remaining near 2 inches...esp if convection is
able to train over areas that have had recent heavy rainfall.

There is still expected to be plenty of cloud cover today which will
help keep temps in check...holding in the 80s.

2%

.LONG TERM...  (Tonight through Friday)
Issued at 353 AM CDT Sat Aug 27 2016

Tonight through Sunday night

500mb pattern is expected to transition from SW flow to zonal with
best flow along the US/Canadian border. The same airmass will be in
place so expect isld/scttrd diurnal convection. It will not be a
wash out but there will be spotty SHRAs/TSTMs around the area.

Temps will remain near average in the mid/upper 80s with lows near
70.

Monday through Friday

Upper flow amplifies next week with a ridge building across the
cntrl CONUS...though not quite as robust as yesterday. The region
will be on the front side of the ridge which will put the FA on the
fringe of NW flow. Guidance is beginning to change solutions for
next week and is now indicating a cold front may drop into the CWA
Tue. If this occurs...temps will trend cooler towards the end of the
week with a lowering PoP trend as well. Not sold on this new
solution just yet. Unfortunately...the mandated model blend that
loads the extended grids incorporated this solution but...would
prefer to hold off advertising this scenario until guidance shows
some continuity. Regardless of what happens mid-week and
beyond...Mon and Tue should remain quite humid with Dps in the
low/mid 70s and highs near seasonal norms in the mid/upper 80s to
near 90. Isld/scttrd diurnal convection will continue as well...with
better coverage on Tue if FROPA occurs.

2%

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1046 PM CDT Fri Aug 26 2016

Weak frontal boundary extended from near MCI to STL this evening.
This front will lift back north-northeastward as a warm front
late tonight and Saturday as the surface ridge over the Great
Lakes region moves eastward. Light east-southeasterly surface
winds late tonight will become mainly southerly on Saturday. Best
chance for convection overnight will be in UIN just north of the
weak front, ahead of an approaching upper level disturbance, and
near a modest southwest low level jet. Isolated to scattered
diurnal convection may develop again over our area Saturday
afternoon.

SPECIFICS FOR KSTL: Weak frontal boundary extended from near
MCI to STL this evening. This front will lift back north-
northeastward as a warm front late tonight and Saturday as the
surface ridge over the Great Lakes region moves eastward. Light
east-southeasterly surface winds late tonight will become mainly
southerly on Saturday. Isolated to scattered diurnal convection
may develop again over our area Saturday afternoon.

GKS

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     89  74  90  74 /  30  30  30  20
Quincy          85  70  86  70 /  30  30  40  20
Columbia        86  70  86  69 /  30  30  30  20
Jefferson City  86  70  87  69 /  30  30  30  20
Salem           87  71  88  71 /  30  20  30  20
Farmington      86  70  87  70 /  30  20  30  20

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX


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