Severe Thunderstorm Warning 9, NWS Dodge City, KS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
305 PM CST SUN MAR 29 1998

LOTS OF UNCERTAINTY EXISTS ON THIS FORECAST PACKAGE REGARDING
THE STRENGTH OF THE COLD AIR WHICH SHOULD POUR SOUTHWARD OVER
THE CENTRAL PLAINS TONIGHT AND MONDAY. TEMPERATURES THIS
AFTERNOON HAVE HELD NEARLY STEADY IN THE UPPER 20S AND 30S ACROSS
EASTERN COLORADO AND WESTERN NEBRASKA. GEOSTROPHIC EASTERLY FLOW
OVER THE NORTHERN PLAINS SUPPORTS EVOLUTION OF A DENSITY CURRENT
WHICH WOULD CARRY THE COLD FRONT SOUTH FASTER AND STRONGER THAN THE
MODELS SUGGEST TONIGHT AND EARLY MONDAY...ALTHOUGH PRESSURE
TENDENCIES DO NOT INDICATE A SIGNIFICANT SOUTHWARD PLUNGE AT THIS
TIME.

PROFILER AND UPPER AIR DATA INDICATE QUITE STRONG WINDS ALOFT OVER
SOUTHWESTERN KANSAS THIS AFTERNOON. COLD AIR ADVECTION APPEARS TO BE
IN PROGRESS OVER SOUTHEASTERN COLORADO SINCE TEMPERATURES ARE
HOLDING NEARLY STEADY EVEN WITH FULL SUN AND STRONG DOWNSLOPE FLOW.
THE PRESSURE GRADIENT OVER WESTERN KANSAS IS NOT SUFFICIENT TO
SUPPORT THE WINDS WHICH ARE OCCURRING...AND DOWNWARD MOMENTUM
TRANSFER IS THE PRIMARY MEANS OF KEEPING THE WINDS UP. WITH THE LOSS
OF SURFACE HEATING TOWARD SUNSET...EXPECT THE WINDS TO DIMINISH
QUICKLY. A HEADLINE FOR THE WIND ADVISORY MAY BE REQUIRED BETWEEN
FORECAST ISSUANCE AND SUNSET...BUT WILL HOLD OFF ON A FINAL DECISION
UNTIL NEAR THE FORECAST DEADLINE.

STRONG RADIATIONAL COOLING IN THE DRY AIR WILL ALLOW TEMPERATURES TO
DROP QUICKLY AFTER SUNSET...ESPECIALLY OVER THE WESTERN PART OF THE
FORECAST AREA. MINIMA SHOULD EXHIBIT A RATHER SUBSTANTIAL RANGE
ACROSS THE AREA SINCE DEWPOINT TEMPERATURES IN THE 50S LIKELY WILL
PERSIST IN THE SOUTHEASTERN ZONES. QUITE WARM AIR ALOFT AND
EXTREMELY WEAK CONVERGENCE ALONG THE DRYLINE SHOULD PRECLUDE
DEVELOPMENT OF ANY CONVECTION IN THE SOUTHEASTERN ZONES THIS
EVENING.

EXTREMELY COLD AIR ALOFT OVER SOUTHERN CALIFORNIA WILL WALLOW ITS
WAY SLOWLY EASTWARD TOWARD THE SOUTHERN AND CENTRAL PLAINS LATE
MONDAY AND MONDAY NIGHT. THE AVN SEEMED TO HAVE THE BEST
INITIALIZATION AT 12Z WITH THE TEMPERATURE STRUCTURE OF THE DEEP
UPPER LEVEL WAVE. ONLY THE AVN PICKED UP WHAT APPEARS TO BE A
SEPARATE COLD POOL OVER SOUTHERN UTAH. THE RGL H5 TEMPERATURES WERE
COLDER THAN WHAT COULD BE INFERRED FROM THE AVAILABLE OBSERVATIONAL
DATA IN THE VICINITY OF THE UPPER COLD POOL. THE RGL/AVN SURFACE
FORECASTS VALID AT 18Z WERE IN BETTER SUBJECTIVE AGREEMENT WITH
OBSERVATIONS OVER NORTHEASTERN COLORADO...ALTHOUGH PRESSURES IN THE
COLD AIR OVER NORTHERN WYOMING WERE SLIGHTLY HIGHER THAN FORECAST BY
ANY OF THE MODELS. GIVEN THE SUBJECTIVELY BETTER INITIALIZATION OF
THE AVN UPPER LEVEL WAVE...THE AVN WILL BE FOLLOWED CLOSELY FOR THE
AFTERNOON PACKAGE. THE PACKAGE WILL...HOWEVER...CARRY THE SURFACE
COLD AIR SOUTHWARD SOMEWHAT FASTER AND STRONGER THAN THE AVN.

WITH THE APPROACH OF THE STRONG...COLD UPPER LEVEL WAVE LATE MONDAY
AND MONDAY NIGHT...EXPECT CYCLOGENESIS TO OCCUR OVER THE TEXAS
PANHANDLE AND FOR THE RESULTING CYCLONE TO RIPPLE NORTHEASTWARD
ALONG THE BAROCLINIC ZONE. WIDESPREAD COLD RAIN SHOULD DEVELOP OVER
SOUTHWESTERN KANSAS AS RICH MOISTURE IS LIFTED OVER THE BAROCLINIC
ZONE. ENOUGH INSTABILITY MAY EXIST OVER THE COLD DOME TO SUPPORT A
FEW EMBEDDED THUNDERSTORMS...BUT WILL RESTRICT MENTION OF CONVECTION
TO THE SOUTHEASTERN ZONES AT THIS TIME. H5 TEMPERATURES MONDAY NIGHT
ARE FORECAST TO COOL TO -26 OR BELOW OVER MOST OF SOUTHWESTERN
KANSAS WITH H7 TEMPERATURES IN THE -8 RANGE.  WITH A FAIR AMOUNT OF
VERTICAL MOTION AND THE EXTREMELY COLD AIR ALOFT...EXPECT THAT THE
PRECIPITATION WILL BECOME MIXED WITH OR CHANGE TO SNOW DURING THE
NIGHTTIME HOURS OVER ALL BUT THE SOUTHEASTERN PART OF THE FORECAST
AREA.  HEAVIEST SNOW AMOUNTS LIKELY WILL BE NO MORE THAN AN INCH OR
TWO A COUPLE OF INCHES ON GRASSY AREAS.  THE AFTERNOON PACKAGE WILL
REFLECT HIGHER POPS THAN MOS GUIDANCE SINCE THE EVENT WILL BE DRIVEN
BY WIDESPREAD SYNOPTIC-SCALE LIFTING.

ON TUESDAY...THE UPPER LEVEL SYSTEM SHOULD LIFT OUT FAIRLY
QUICKLY...AND CLOUDINESS SHOULD DECREASE FROM THE WEST. MOS
TEMPERATURES APPEAR TO BE REASONABLE.

EXTENDED PERIOD...
EXTENDED DISC...LAST NIGHTS MRF MORE IN LINE WITH THE MRF
RUN OF 2 DAYS AGO ACCORDING TO DPROG/DT CENTERED ON THE
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT TIME FRAME. NEXT UPPER SYSTEM
FORECAST TO MOVE OVER THE CENTRAL AND SOUTHERN PLAINS DURING THE MID
TO LATE PART OF THIS WEEK. THEREFORE...I WILL CONTINUE WITH A SLOW
WARMING TREND AND KEEP THE POPS GOING FOR THURSDAY. FRIDAY WILL BE
COOLER AS THE UPPER SYSTEM EXITS THE REGION AND USHERS IN COOLER
AIR.

.DDC...NONE.

DDC 043/051 033/055 033 048
GCK 040/050 032/056 031 046
EHA 038/052 032/059 034 034
LBL 044/054 034/057 034 048
HYS 043/050 033/050 032 057
P28 054/063 039/057 037 -47

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