AND CNTRL INDIANA
CONCERNING...TORNADO WATCH 1...
VALID 170750Z - 170915Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 1 CONTINUES.
SEVERE THREAT IS DIMINISHING ACROSS SOUTHWEST AND SOUTH CENTRAL
MISSOURI. TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF AN
ADDITIONAL WW EAST OF WW 0001.
VIGOROUS CONVECTIVE DEVELOPMENT APPEARS GENERALLY ASSOCIATED WITH
DEEP LAYER UPWARD VERTICAL MOTION...SUBSTANTIALLY FORCED BY A SHORT
WAVE IMPULSE/MID-LEVEL JET STREAK NOW TURNING EASTWARD ACROSS THE
CENTRAL PLAINS. THROUGH THE 09-12Z TIME FRAME...MODELS SUGGEST THAT
THIS STRONGER LIFT WILL RAPIDLY SHIFT EAST OF THE ST. LOUIS
AREA...ACROSS CENTRAL ILLINOIS...INTO NORTH CENTRAL INDIANA. EVEN
WITH A 40-60 KT WEST SOUTHWESTERLY 850 MB JET AIDING THE TRANSPORT
OF INCREASINGLY MOIST LOW-LEVEL AIR INTO THIS REGION...THE EVOLVING
MESOSCALE CONVECTIVE SYSTEM WILL PROBABLY BEGIN OUTRUNNING MORE
FAVORABLE WARM SECTOR NEAR SURFACE INSTABILITY. WHEN THIS
OCCURS...ACTIVITY SHOULD BECOME INCREASINGLY ELEVATED IN
NATURE...WITH A DIMINISHING SEVERE THREAT...ALTHOUGH MORE HIGHLY
LOCALIZED STRONG SURFACE GUSTS ASSOCIATED WITH THE DOWNWARD
TRANSPORT OF HIGHER MOMENTUM AIR MAY STILL NOT BE OUT OF THE
QUESTION. GIVEN THE CURRENT 50 KT STORM MOTION...AND UNCERTAIN
TIMING OF WEAKENING TRENDS...IT MAY BE THAT THE SEVERE THREAT
REMAINS HIGH ENOUGH TO REQUIRE AN ADDITIONAL WW ALONG THE INTERSTATE
70 CORRIDOR OF ILLINOIS AND INDIANA EARLY THIS MORNING.
..KERR.. 01/17/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...ILN...LMK...IWX...IND...PAH...LOT...ILX...LSX...
LAT...LON 40168892 41098709 41028498 39768483 38228706 37559015
37979130 38948975 40168892
