Heat in Kansas, July 31, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
309 PM CDT TUE JUL 31 2001

...MAIN QUESTIONS THIS CYCLE WILL BE TEMPERATURES AND CHANCES FOR
EVENING/OVERNIGHT CONVECTION...

THE 12Z ANALYSIS PACKAGE SHOWED A VIGOROUS UPPER LEVEL SHORT WAVE
TROUGH OVER THE NORTHWESTERN CONUS MOVING EAST INTO THE NORTHERN
PLAINS REGION WHILE AN UPPER LEVEL RIDGE DOMINATED THE MISSISSIPPI
VALLEY REGION WESTWARD INTO THE PLAINS. THE MID AND LOWER
TROPOSPHERE THERMAL RIDGE WAS ACROSS THE WESTERN HIGH PLAINS FROM
SOUTH TO NORTH WHILE WATER VAPOR IMAGERY SHOWED THE PLUME OF
SUBTROPICAL MOISTURE MOVING NORTH FROM OLD MEXICO TO BE THINNING
WITH TIME. AT 12Z A 50KT LOW LEVEL JET WAS ACROSS FAR WESTERN KANSAS
INTO WESTERN NEBRASKA WITH A STRONG MOIST TONGUE FROM CENTRAL TEXAS
NORTH INTO EASTERN KANSAS AT H8. THE KDDC MORNING SOUNDING MODIFIED
FOR UPPER 90S OVER MID 60S DEWPOINTS GIVES AN UNCAPPED INVERTED V
SIGNATURE WITH AN LCL AROUND 8K FEET AND AROUND 2800 J/KG OF B+. WET
BULB ZERO WAS AT 12.5K FEET. THE SOUNDING FAVORS HIGH BASED
MULTICELLULAR STORMS IN A DOWNBURST ENVIRONMENT DUE TO THE DEEP DRY
LAYER BELOW.

MODEL INITIALIZATIONS TODAY WERE ALL QUITE GOOD AND THEY ARE IN
REASONABLY GOOD AGREEMENT WITH TIME. THE NGM APPEARS TOO PROGRESSIVE
IN LATER PERIODS WHILE THE AVN STRUGGLES A BIT WITH THE MSL PRESSURE
FIELDS IN THE LEE OF THE ROCKIES. ALL OF THEM MOVE THE SHORT WAVE
TROUGH ALOFT ACROSS THE NORTHERN PLAINS TODAY AND TONIGHT WITH THE
POLAR COLD FRONT PUSHING THE HEAT LOW NOW OVER THE DAKOTAS AND
NEBRASKA SOUTH INTO WEST KANSAS AND EAST COLORADO BY WEDNESDAY
MORNING WITH THE POLAR FRONT CLOSE ON ITS HEELS. AFTERNOON AND
EVENING CONVECTION ALONG THE FRONT SHOULD ASSIST IN THIS PROCESS.
THE EFFECT OF THIS IS TO ELONGATE THE UPPER LEVEL RIDGE OVER THE
CENTRAL CONUS SO THAT BY WEDNESDAY EVENING THE HIGH ENDS UP CENTERED
OVER KANSAS AND OKLAHOMA WITH THE POLAR FRONT STALLED ALONG THE
KANSAS NEBRASKA BORDER. THIS WILL ALSO EFFECTIVELY MOVE THE
SUBTROPICAL PLUME FARTHER NORTH. WITH THE HEAT LOW ENDING UP OVER
THE CENTRAL HIGH PLAINS, LOW LEVEL WINDS ARE FORECAST TO VEER AND
SHUNT THE DEEPER MOISTURE EASTWARD ACROSS KANSAS. VERY HOT AIR OVER
THE REGION LOOKS TO CONTINUE WITH DEWPOINTS REMAINING FAIRLY HIGH
FOR THE SEASON BUT IN SPITE OF THE THERMODYNAMIC INSTABILITY THE
COMBINATION OF VERY WARM AIR ALOFT AND LACK OF A TRIGGER SHOULD
PRECLUDE MUCH IN THE WAY OF CONVECTION TONIGHT INTO WEDNESDAY.

D3D INTERROGATION OF THE MODELS INDICATES A FAIR AMOUNT OF UPWARD
MOTION ALONG THE FRONT AND ACROSS THE NORTHERN 1/2 OF MY ZONES BY
WEDNESDAY EVENING. THE ISOSURFACES OF OMEGA AT THIS TIME WERE
COINCIDENT WITH ISOSURFACES OF DIVERGENCE/CONVERGENCE WHILE THERE
WAS LITTLE IN THE WAY OF TEMPERATURE ADVECTION SHOWN. AN ISOSURFACE
OF WIND SPEED INDICATED A JET STREAK ROTATING THROUGH THE REGION AT
THIS TIME THUS BELIEVE THE MODELS ARE SHOWING THAT MOST OF THE LIFT
WILL BE CAUSED BY THE JET STREAK AND CONVERGENCE ON THE FRONT. BASED
ON THIS, WILL INCLUDE SOME SMALL CHANCE POPS IN THAT AREA FOR
WEDNESDAY NIGHT. NONE OF THIS WAS EASILY APPARENT USING 2D
VISUALIZATION.

GIVEN THE ABOVE DISCUSSION, THE MOS GUIDANCE LOOKS GOOD FOR ALL
EXCEPT HIGH TEMPERATURES WHICH APPEAR A BIT TOO COOL. WILL INCLUDE
SOME VERY SMALL CHANCE POPS IN MY FAR NORTHWEST ZONES BOTH TONIGHT
AND TOMORROW NIGHT TO COVER CONVECTION WHICH MAY MOVE SOUTH OFF THE
FRONT BUT OTHERWISE A HOT AND DRY FORECAST. THE NOCTURNAL
OSCILLATION OF THE LOW LEVEL JET OVER THE HIGH PLAINS SHOULD HELP
KEEP MIXING GOING OVERNIGHT AND WILL THUS KEEP LOW TEMPERATURES UP.
MY SOUTHEAST ZONES WILL FLIRT WITH HEAT ADVISORY CRITERIA BUT WITH
OVERNIGHT LOWS IN THE 70S WILL NOT RUN UP THAT FLAG JUST YET.

EXTENDED DISCUSSION...
W/V AND 5H LOOP SHOWING EASTERN PACIFIC RIDGE RETROGRADING AS A
SERIES OF S/W'S CROSS OVER THIS RIDGE THEN DROP SOUTH INTO THE WEST
COAST TROF. THIS COMBINED WITH THE INCREASE IN AAM AND A MOIST PHASE
OF THE MJO WEST OF 120E SUGGESTS THAT A MORE ZONAL FLOW LIKELY TO
CONTINUE INTO EARLY IN THE EXTENDED PERIOD. THE RETROGRADING RIDGE
IN THE PACIFIC HOWEVER SHOULD BEGIN TO BUILD LATER IN THE WEEKEND
AND EACH SUCCESSIVE WAVE THAT DROPS SOUTH INTO THE EASTERN PACIFIC
SHOULD ALSO ONCE AGAIN DEEPEN THE WEST COAST/EASTERN PACIFIC TROF.
THIS SHOULD RESULT IN RISING HTS DOWNSTREAM OVER THE PLAINS. WILL
THEREFORE CONTINUE WITH THE DRY AND HOT FORECAST FOR SATURDAY
THROUGH MONDAY. UNTIL THEN HOWEVER THERE SHOULD CONTINUE TO BE WEAK
WAVES EMBEDDED IN OUR FLOW AROUND THE UPPER RIDGE IN THE PLAINS SO
AT THIS TIME CONFIDENCE IS NOT HIGH ENOUGH TO REMOVE CHC/SLT CHC
POPS ON FRIDAY.

FOR TUESDAY INTO THE 8 TO 10 DAY PERIOD WILL LEAN TOWARDS THE
GENERAL TREND OF ALL MODELS WITH THE THE UPPER LOW IN THE EASTERN
PACIFIC SHIFTING EASTWARD AND THE RIDGE ALOFT WEAKENING. THIS MAY
BRING A SLIGHTLY BETTER CHANCE IN PCPN TOWARDS MID WEEK. TEMPS
SHOULD HOWEVER STAY ABOVE NORMAL.

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

DDC 075/101 073/101 073 112
GCK 074/100 071/100 071 112
EHA 070/102 070/102 070 ---
LBL 074/103 072/103 072 ---
HYS 075/100 075/100 075 112
P28 077/106 076/105 076 ---

.DDC...NONE.

JOHNSON/BURGERT