692
FXUS63 KLSX 162048
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
348 PM CDT MON SEP 16 2019
SHORT TERM
(THROUGH LATE TONIGHT)
ISSUED AT 255 PM CDT MON SEP 16 2019
WEAK CONVERGENCE WAS NOTED ALONG A BACK-DOOR COLD FRONT WHICH HAD
SETTLED INTO THE REGION. SCATTERED SHRA/TSRA HAVE ALREADY
DEVELOPED FARTHER EASTWARD ALONG THE BOUNDARY IN IN/KY/OH WHERE
METARS SHOWED STRONGER SURFACE CONVERGENCE. BASED ON SATELLITE
DEPICTIONS OF THE CUMULUS FIELD OVER MO/IL AS WELL AS BUFKIT
SOUNDINGS SHOWING VERY LITTLE CINH, THE PREVIOUS SHIFT'S
EXPECTATION FOR ISOLATED SHRA/TSRA STILL LOOKS ON TRACK. HOWEVER,
THE LOCATION OF THESE POPS HAS BEEN ADJUSTED SLIGHTLY EASTWARD TO
REFLECT THE LATEST POSITION OF THE SURFACE FRONT.
LOWS TONIGHT SHOULD RANGE FROM THE MID 60S IN SW IL (ON THE COOLER
SIDE OF THE STALLED BOUNDARY) TO AROUND 70 IN CENTRAL MO. THE
COMBINATION OF LIGHT WINDS AND MOISTURE POOLING NEAR THE FRONT
COULD ALSO LEAD TO LIGHT FOG DEVELOPMENT TONIGHT. THE ONLY
INHIBITING FACTOR WILL BE SOME MID/HIGH CLOUDS SPILLING INTO THE
REGION, AND THIS MAY RESULT IN PATCHY FOG DEVELOPMENT WITHIN ANY
BREAKS IN THE CLOUDS.
KANOFSKY
LONG TERM
(TUESDAY THROUGH NEXT MONDAY)
ISSUED AT 255 PM CDT MON SEP 16 2019
WARM AND HUMID CONDITIONS ARE EXPECTED TO PERSIST FOR THE REST OF
THE WEEK DUE TO THE COMBINED INFLUENCE OF AN UPPER RIDGE AXIS AS
WELL AS SOUTHERLY FLOW ALONG THE PERIPHERY OF A SURFACE HIGH
PRESSURE CENTER. HIGHS WILL GENERALLY BE IN THE UPPER 80S TO LOWER
90S AND OVERNIGHT LOWS WILL BE IN THE 60S TO LOWER 70S.
SOME MODELS SHOW A FEW WEAK DISTURBANCES DURING THE WEEK WHICH
COULD PRODUCE ISOLATED SHRA/TSRA, BUT THE BEST CHANCE FOR
WIDESPREAD RAINFALL APPEARS TO BE FROM FRIDAY THROUGH SUNDAY NIGHT
WHEN A LOW PRESSURE SYSTEM LIFTS THROUGH THE NORTH-CENTRAL CONUS
TOWARDS CANADA. MODELS ALL SHOW A SECONDARY DISTURBANCE MOVING
INTO THE TROUGH AFTER THE FIRST LOW PRESSURE SYSTEM HAS LIFTED
NORTHEASTWARD, BUT THERE IS POOR AGREEMENT BETWEEN MODELS ON THE
RESULTING LARGE SCALE UPPER AIR PATTERN. THAT SAID, MODELS DO
APPEAR TO BE IN GENERAL AGREEMENT THAT A PATTERN CHANGE WILL BRING
A PERIOD OF WETTER WEATHER TO THE REGION THIS WEEKEND AND PERHAPS
INTO EARLY NEXT WEEK. TEMPERATURES SHOULD BE LOWER THIS WEEKEND
DUE TO CLOUDS AND RAIN, AND THERE IS AT LEAST A CHANCE THAT A
FRONTAL BOUNDARY COULD EVEN PUSH THROUGH THE REGION AND BRING
COOLER TEMPERATURES TO THE AREA.
KANOFSKY
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1226 PM CDT MON SEP 16 2019
VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS. THERE IS A SLIM
CHANCE OF A THUNDERSTORM BETWEEN 18-24Z NEAR A WEAK COLD FRONT
WHICH IS MOVING INTO THE AREA FROM THE NORTHEAST, BUT SHRA/TSRA
CHANCES ARE TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. PATCHY
LIGHT FOG IS ALSO POSSIBLE AFTER 17/09Z.
KANOFSKY
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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