Severe Thunderstorm Warning 401, NWS Dodge City, KS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
342 PM CDT THU SEP 20 2001

MAIN FORECAST CHALLENGE IS POPS TONIGHT, AND RESULTANT TEMPERATURE
CHANGE DUE TO COLD FRONT PASSAGE.

THE COLD FRONT IN NW KANSAS WAS RACING SOUTHEAST AT A GOOD CLIP
EARLY TODAY, BUT SLOWED SOMEWHAT AS IT ENCOUNTERED STRONGER SOUTH
LOW LEVEL FLOW LEFT OVER FROM NOCTURNAL JET COMING NORTH FROM
OKLAHOMA.  HIGHER DEW POINT AND THETA E AIRMASS SOUTHEAST OF A LINE
AT 20Z FROM NEAR GREAT BEND TO DODGE CITY TO MEADE.  THINK THERE
WILL BE A FEW STORMS FIRE THIS EVENING IN SOUTHEASTERN CWA ALONG
EITHER THE PRE-FRONT DRY LINE, OR A BIT LATER ALONG THE FRONT AS
IT CROSSES.

WILL MENTION POSSIBLE SEVERE IN SOUTHEAST 5 COUNTIES, AND PLAN AT
THIS MOMENT FOR A SILENT 20 POP OVER REST OF CWA.

LOWS OVERNIGHT TO DROP FASTEST IN THE WEST WHERE DRY ADVECTION HAS
BEEN TAKING PLACE.  THE SOUTHEAST MAY NOT DROP BELOW MID 60S AS
MOISTURE DRAGS BEHIND FRONT CLEARING OUT.   WILL HAVE TO WAIT AND
SEE IF ANY MORE MOISTURE ADVECTS BACK NORTH OVERRIDING FRONT, WHICH
SHOULD BE RETREATING SOUTHEASTWARD FRIDAY.

INCREASING CLOUDS WITH NEAR SAME LOW TEMPS FOR FRIDAY NIGHT.  AN
UPPER WAVE ENTERS FROM THE SOUTHWEST LATE FRIDAY NIGHT, SO
INTRODUCED 20 POPS WEST FRI NIGHT AND SAT MORNING.  THEN, MERGED 20
POPS EAST ACROSS ENTIRE CWA FOR SATURDAY. AVN IS FASTEST WITH
BRINGING IN THIS SOUTHWEST SYSTEM, BUT FAVOR THE NGM TIMING AND IS
BETTER OVERALL.  ETA DOES NOT BRING IN ANY PRECIP BEYOND WESTERN
TIER OF COUNTIES SATURDAY.  THUS, 20 POP SHOULD HANDLE IT.  THINK
THE WEST MIGHT DESERVE A LITTLE HIGHER CHANCE POP, BUT WILL LET
LATER SHIFTS ADJUST IF NECESSARY.

EXTENDED DISCUSSION...

A MUCH MORE AMPLIFIED FLOW REGIME IS DEVELOPING OVER THE CONUS AS
COLD AIR ENTERS THE GULF OF ALASKA ALLOWING A DEEP LOW TO FORM HERE,
THUS BRINGING STRONG RIDGING OVER THE WESTERN CONUS AND A DEEP FULL
LATITUDE TROF OVER THE EAST THIS WEEKEND. THIS JIVES WELL WITH THE
VERY LOW ANGULAR MOMENTUM VALUES. MODEL SKILL SCORES REMAIN TO BE
QUITE HIGH AND ARE IN GOOD CONSENSUS WITH THE SCENARIO AT THIS
RANGE HOWEVER DIFFERENCES BEGIN TO APPEAR WITH THE PLACEMENT AND
DEPTH OF THE EASTERN LOW FOR EARLY NEXT WEEK. ENSEMBLE MRF MEMBERS
ARE NOT QUITE AS ROBUST AND AS FAR WEST WITH THE LOW AS THE
OPERATIONAL MRF AND WILL FOLLOW THEM MORE CLOSELY. WESTERLIES
EXPANDING OVER THE NORTHERN PACIFIC SHOULD ALLOW A MORE PROGRESSIVE
PATTERN TO EVOLVE BY MID WEEK AND BRING THE RIDGE EAST OVER THE
ROCKIES BY DAY 7.

SHORTWAVE ASSOCIATED WITH THIS TRANSITION TO SWING INTO THE PLAINS
SATURDAY NIGHT AND BRING A SIGNIFICANT COLD FRONT THROUGH THE CWA BY
SUNDAY MORNING. WILL NEED TO KEEP PRECIPITATION CHANCES GOING
SATURDAY NIGHT AND SUNDAY WITH THE FRONT AND UPPER TROF AXIS MOVING
THROUGH. COLD AIR SHOULD ENTRENCH ITSELF OVER THE HIGH PLAINS SUNDAY
AND MONDAY AND WILL NEED TO DROP TEMPS CONSIDERABLY HERE. WARMUP
SHOULD BEGIN BY MID WEEK AND WILL TREND TOWARD ABOVE NORMAL TEMPS IN
THE 8 TO 10 DAY PERIOD.

PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE
CONTAINED WITHIN THE DODGE CITY ZONE FORECAST.

DDC 060/079 062/084 055 200
GCK 059/079 060/084 053 100
EHA 058/079 059/086 053 --0
LBL 060/079 060/085 055 2-0
HYS 058/078 058/082 054 000
P28 064/082 064/086 059 3-0

.DDC...NONE.

BURKE/POAGE