Severe Thunderstorm Warning 11, NWS Springfield, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
230 AM CST THU FEB 17 2000

MAIN FOCUS THIS PERIOD WILL BE WITH IMPRESSIVE WINTER STORM TODAY
THROUGH FRIDAY MORNING.

CONVECTION CURRENTLY OCCURRING ACROSS N AR/S MO IN RESPONSE TO LOW
LEVEL THETA-E ADVECTION AND WAA/ISENTROPIC LIFT.  I300 SURFACE
REALLY SHOWS THIS WELL.  MAIN UPPER LEVEL SYSTEM STILL WELL OUT IN
THE WESTERN ROCKIES...WITH SFC LOW STARTING TO DEVELOP OVER CO.

00Z SGF SOUNDING SHOWS A LOT OF DRY AIR IN THE LOWER LEVELS AND
SHALLOW LAYER OF COLD AIR NEAR THE SURFACE.  THIS LOOKS TO QUICKLY
ERODE TODAY AS STRONG WAA TAKES PLACE.

MODELS LOOK IN GENERAL AGREEMENT WITH UPPER LEVEL FEATURES HOWEVER
STILL HAVE SOME DIFFERENCES WITH THE PLACEMENT OF THE SFC LOW.  NGM
SHOW TYPICAL BIAS OF PLACING SURFACE LOW TO FAR N...AND IS ALSO
SLOWER IN THE LATER PERIODS PUSHING THE LOW EASTWARD.  HAVE OPTED
FOR AN ETA/AVN SOLUTION FOR GUIDANCE THROUGH THE PD.

ETA/AVN MODEL SOUNDINGS CERTAINLY PAINT A DIFFERENT PICTURE THAN 24
HOURS AGO.  LAST NIGHT SOUNDINGS WERE INDICATING A POTENTIAL OF
SIGNIFICANT ICING ACROSS MY CENTRAL MO COUNTIES DURING THE DAY
TODAY.  NOW IT LOOKS AS IF IT MIGHT BEGIN WITH A MIXTURE EARLY THEN
CHANGE TO ALL RAIN BY NO LATER THAN MIDDAY...WITH THE
FREEZING/FROZEN PRECIPITATION FURTHER TO THE N.  WAA LOOKS TO BE
STRONGER THAN YESTERDAYS MODEL RUNS AND PUSHES INTO THE AREA
QUICKER.  WILL NOT TAMPER WITH CURRENT ADVISORY ACROSS CENTRAL MO
COUNTIES BUT WILL CHANGE WORDING TO MAINLY THIS MORNING.

ON THE OTHER SIDE OF THE COIN...THERE EXISTS THE POTENTIAL FOR
SEVERE WEATHER AND HEAVY RAIN ACROSS THE SOUTHERN PORTION OF THE
STATE.

WAA/ISENTROPIC LIFT SHIFTS INTO MUCH OF CWA DURING THE MORNING AND
SHOULD SEE INCREASE IN AREAL COVERAGE TOWARDS SHIFT CHANGE.  THE
BEST WAA/ISENTROPIC LIFT WILL BE NORTH OF THE CWA TONIGHT...BUT
SHOULD BE ENOUGH DYNAMIC LIFT AS LOW/CDFNT PUSH INTO THE AREA.
MOISTURE ALSO WILL NOT BE A PROBLEM TONIGHT AS ETA SHOWS A 70+ KT
LOW LEVEL JET ACROSS S MO.  LOOKS LIKE THE BEST CHANCE OF SUPERCELL
DEVELOPMENT WILL REMAIN S OF THE AREA TODAY...WITH THE BEST CHANCE
OF SEVERE WEATHER ACROSS CWA BEING TONIGHT AS A LINE OF TSRA SHOULD
DEVELOP ALONG/AHEAD OF CDFNT.  HEAVY RAIN AREA SHOULD REMAIN NORTH
OF WARM FRONT TODAY AND TONIGHT ACROSS S/CNTRL MO.  WILL NOT
HEADLINE AND FFA AT THIS TIME DUE TO FAIRLY DRY GROUND CONDITIONS.

COLDER AIR SHOULD PUSH IN BEHIND THE FRONT ON FRIDAY...AND WITH LOW
CLOUDS CONTINUING WILL NOT SEE MUCH OF A TEMPERATURE RISE.  NGM
LOOKS TOO SLOW WITH THE LOW/FRONT COMBO PUSHING EAST AND AS A RESULT
THE FWC GUIDANCE LOOKS TOO WARM WITH TEMPS ON FRIDAY.  HAVE TRENDED
TOWARDS THE COOLER FAN NUMBERS THEN.

SGF WC 048/042 045/022 045 059+4-
JLN TC 052/045 047 024 048 059+3-
UNO TW 046/043 050/028 045 059+5-
VIH RW 042/039 042/020 042 059+61

.SGF...WINTER WEATHER ADVISORY THIS MORNING NORTH OF A LINE FROM
WARSAW TO CAMDENTON TO SALEM.

LINDENBERG

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