000
FXUS63 KDDC 181738
AFDDDC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
1238 PM CDT SAT MAY 18 2013

...UPDATED AVIATION SECTION...

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 200 AM CDT SAT MAY 18 2013

SHORT RANGE MODELS INDICATE THE UPPER LEVEL TROUGH IN THE FOUR
CORNERS REGION PUSHING FURTHER EAST INTO THE CENTRAL AND SOUTHERN
ROCKIES TODAY SETTING THE STAGE FOR SHOWERS AND THUNDERSTORMS FROM
THE NORTHERN PLAINS SOUTHWARD INTO THE CENTRAL PLAINS OF KANSAS. AS
THE UPPER LEVEL TROUGH APPROACHES, A JET CORE EXITING THE TROUGH
AXIS IS PROJECTED TO MOVE EAST INTO THE WESTERN HIGH PLAINS BY MID
TO LATE AFTERNOON PROVIDING FAVORABLE DYNAMIC SUPPORT ALOFT,
INCLUDING STRONG DIVERGENT FIELDS ACROSS CENTRAL AND WESTERN KANSAS.
MEANWHILE, A STRENGTHENING SURFACE LOW IN SOUTHEASTERN COLORADO,
ACCOMPANIED BY THE SHARP DRYLINE EXTENDING SOUTHWARD, IS EXPECTED
TO EDGE SLOWLY EASTWARD INTO SOUTHWEST KANSAS THIS AFTERNOON
ENHANCING LOW LEVEL CONVERGENCE ACROSS SOUTHWEST KANSAS INITIALLY,
THEN EASTWARD ACROSS CENTRAL KANSAS. NAM/GFS MODEL SOUNDINGS SHOW
SUBSTANTIAL INSTABILITY ACROSS CENTRAL AND SOUTHWEST KANSAS WITH
CAPE VALUES WELL IN EXCESS OF 4000 J/KG BY THE AFTERNOON HOURS.
THE MODEL SOUNDINGS ALSO INDICATE FAVORABLE DEEP LAYER SHEAR
PROFILES INCREASING AS LOWER LEVEL LAPSE RATES STEEPEN THROUGHOUT
THE AFTERNOON. AS A RESULT, STRONG TO SEVERE THUNDERSTORM
DEVELOPMENT WILL BE POSSIBLE ACROSS CENTRAL AND PORTIONS OF
SOUTHWEST KANSAS LATE THIS AFTERNOON THROUGH THIS EVENING WITH
THE POTENTIAL EXISTING FOR VERY LARGE HAIL AND DAMAGING WINDS.
ADDITIONALLY, THE SHEAR PROFILE IS SUCH THAT TORNADOES MAY BE
POSSIBLE WITH THE STRONGEST OF STORMS, ESPECIALLY INTO THE EVENING
ONCE A STRONG LOW LEVEL JET DEVELOPS AHEAD OF THE SURFACE LOW.

TEMPERATURES WILL ONCE AGAIN CLIMB ABOVE NORMAL TODAY AS THE SURFACE
LOW IN SOUTHEASTERN COLORADO CONTINUES TO INFLUENCE A SOUTH TO
SOUTHEASTERLY LOW LEVEL FLOW INTO WESTERN KANSAS. TEMPERATURES AT
H85 WILL REMAIN SIMILAR TO YESTERDAY WITH VALUES RANGING FROM AROUND
TO JUST ABOVE 20C IN CENTRAL KANSAS TO NEAR 30C IN FAR SOUTHWEST
KANSAS. EXPECT HIGHS UP INTO THE 80S(F) IN CENTRAL KANSAS WITH THE
LOWER TO MID 90S(F) POSSIBLE IN EXTREME SOUTHWEST KANSAS, ESPECIALLY
ONCE THE DRYLINE MOVES THROUGH THIS AFTERNOON. LOOK FOR LOWS BACK
DOWN INTO THE 60S(F) WITH MID TO UPPER 50S(F) POSSIBLE NEAR THE
COLORADO BORDER AS A LOW LEVEL NORTHERLY FLOW SETS UP BEHIND THE
ADVANCING SURFACE LOW.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT MAY 18 2013

THE COLD UPPER LEVEL TROUGH EXTENDING FROM WESTERN UTAH TO
ARIZONA WILL PROGRESS EASTWARD TOWARD THE CENTRAL PLAINS SUNDAY,
AND THE NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH EVOLUTION OF A
CLOSED CYCLONE IN NEBRASKA BY SUNDAY AFTERNOON. A STRONG JET
SEGMENT WITH A VORTICITY MAXIMUM EVIDENT ON SATELLITE IMAGERY NEAR
127W WILL DIG INTO THE SOUTHWESTERN PART OF THE COUNTRY MONDAY AND
WILL APPROACH WESTERN KANSAS MONDAY NIGHT. A VERY BLOCKY FLOW
REGIME WILL PREVAIL THROUGH MUCH OF NEXT WEEK AS UPPER LEVEL
ANTICYCLOGENESIS OCCURS IN SOUTHERN SASKATCHEWAN AND MANITOBA
MONDAY AND TUESDAY, AND UNSEASONABLY COLD MID LEVEL TEMPERATURES
WITH BROAD CYCLONIC UPPER LEVEL FLOW WILL PERSIST ACROSS KANSAS
THROUGH MID WEEK. UPPER LEVEL RIDGING WILL BUILD IN THE CENTRAL
UNITED STATES AS THE UPPER LEVEL CYCLONE FINALLY PROGRESSES EAST
THURSDAY AND FRIDAY. A COOL SURFACE ANTICYCLONE WILL BUILD EAST OF
THE CANADIAN UPPER LEVEL ANTICYCLONE, AND A RIDGE OF HIGH PRESSURE
WILL BUILD INTO THE CENTRAL PART OF THE COUNTRY THURSDAY AND
FRIDAY. MOIST UPSLOPE FLOW WILL FAVOR CONSIDERABLE CLOUDINESS AND
ENHANCED CHANCES FOR RAINFALL THURSDAY THROUGH SATURDAY.

TROPICAL THUNDERSTORMS HAVE BEEN ACTIVE FOR THE LAST WEEK NEAR THE
MARITIME CONTINENT AND ACROSS THE INDIAN OCEAN. THE GFS SUGGESTS
THAT A COHERENT CLUSTER PROJECTING ONTO A MADDEN-JULIAN OSCILLATION
WILL MOVE INTO THE WESTERN HEMISPHERE NEXT WEEK, BUT THE ECMWF IS
MUCH LESS AGGRESSIVE WITH AN EASTWARD PROPAGATING SIGNAL. THE GFS
MAY BE PICKING UP ON A FASTER PROPAGATING MODE OF CONVECTION, AND
THE MORE CONSERVATIVE ECMWF SEEMS MORE REASONABLE. RELATIVE
ATMOSPHERIC ANGULAR MOMENTUM STILL IS ABOVE CLIMATOLOGY, BUT THE
TENDENCY IS NEGATIVE. THE GENERAL FLOW IS TRENDING WEAKLY TOWARD
PHASE 8 OF THE BERRY-WEICKMANN PHASE-SPACE DIAGRAM, AND THIS PATTERN
FAVORS CYCLONIC FLOW IN THE WESTERN UNITED STATES. THE DETERMINISTIC
MODELS ARE IN GOOD AGREEMENT WITH DEVELOPING AN UPPER LEVEL LOW IN
THE PACIFIC NORTHWEST TUESDAY, AND THIS SEEMS REASONABLE.

A PACIFIC COLD FRONT WILL PROGRESS INTO CENTRAL KANSAS BY EARLY
SUNDAY AFTERNOON, AND SEVERE THUNDERSTORMS LIKELY WILL DEVELOP FROM
OKLAHOMA INTO EASTERN KANSAS NEAR THE FRONT. MUCH COOLER AIR IN THE
MID LEVELS OF THE ATMOSPHERE WILL INVADE WESTERN KANSAS SUNDAY, AND
MID LEVEL INSTABILITY AND UPWARD VERTICAL MOTION IN ADVANCE OF THE
VIGOROUS UPPER LEVEL TROUGH WILL FAVOR DEVELOPMENT OF SHOWERS AND
THUNDERSTORMS SUNDAY MORNING IN FAR WESTERN KANSAS. WITH SURFACE
HEATING DURING THE DAY, SHOWERS AND THUNDERSTORMS WILL BECOME MORE
WIDESPREAD. WITH H5 TEMPERATURES AROUND -15C SUNDAY AFTERNOON AND
MORE THAN 1000 J/KG OF CAPE, THERE PROBABLY WILL BE HAIL WITH A FEW
OF THE THUNDERSTORMS. TEMPERATURES WILL WARM INTO THE MID 80S IN
SOUTH CENTRAL KANSAS WHERE LITTLE COLD AIR ADVECTION WILL OCCUR
UNTIL LATE AFTERNOON, WHILE HIGHS WILL REACH ONLY THE LOWER 70S NEAR
THE COLORADO BORDER. THUNDERSTORM ACTIVITY WILL WEAKEN WITH LOSS OF
HEATING SUNDAY EVENING.

A TROUGH ROTATING AROUND THE COLD UPPER LEVEL CYCLONE WILL CARRY A
REINFORCING SURGE OF COLD AIR INTO KANSAS MONDAY, AND CHANCES FOR
LARGELY DIURNAL SHOWERS AND THUNDERSTORMS UNDER THE UPPER LEVEL COLD
POOL WILL CONTINUE. ANOTHER UPPER LEVEL TROUGH WILL APPROACH THE
CENTRAL PLAINS TUESDAY, AND ANOTHER ROUND OF SHOWERS CAN BE EXPECTED
PRIMARILY FROM WEST CENTRAL INTO NORTH CENTRAL KANSAS. WEDNESDAY
SHOULD BE QUIET WITH UPPER LEVEL RIDGING AND LIMITED INSTABILITY. BY
THURSDAY, LOW LEVEL MOISTURE WILL BEGIN TO FLOW BACK INTO THE HIGH
PLAINS ON THE WEST SIDE OF THE EXTENSIVE SURFACE ANTICYCLONE, AND
THUNDERSTORMS ARE LIKELY TO DEVELOP IN EASTERN COLORADO AND
PROPAGATE INTO WESTERN KANSAS DURING THE EVENING AND NIGHTTIME
HOURS. THE ECMWF IS MORE AGGRESSIVE THAN THE GFS WITH WEAKENING THE
RIDGE IN THE CENTRAL PLAINS AND SPREADING WARM MID LEVEL
TEMPERATURES INTO WESTERN KANSAS, BUT THE SLOWER EVOLUTION OF THE
GFS SEEMS MORE REASONABLE GIVEN THE BLOCKY FLOW REGIME THAT HAS
PERSISTED THIS MONTH. TEMPERATURES WILL BE NEAR OR BELOW SEASONAL
AVERAGES WITH HIGHS GENERALLY IN THE 70S AND LOWER 80S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1232 PM CDT SAT MAY 18 2013

VFR CONDITIONS WILL BE OBSERVED THIS AFTERNOON WITH THE EXCEPTION
OF THE HAYS AREA OVER THE NEXT HOUR DUE TO LEFT OVER CLOUDS AOA030 FROM
LAST NIGHT. THESE CLOUDS SHOULD MOVE OUT OF THE AREA BY 19Z
LEAVING VFR CONDITIONS. THUNDERSTORMS ARE POSSIBLE ACROSS THE TAF
SITES LATE THIS AFTERNOON INTO THIS EVENING AS A STRONG UPPER
LEVEL DISTURBANCE MOVES THROUGH THE AREA. THESE STORMS ARE
ANTICIPATED TO FORM ALONG A DRYLINE ACROSS WESTERN KANSAS FIRST
THEN SPREAD ACROSS THE REMAINDER OF WESTERN KANSAS AS THE EVENING
PROGRESSES. I HAVE KEPT A VCSH IN THE TAFS FOR NOW BUT MAY NEED TO
BE UPDATED LATER ON WHEN STORMS START TO DEVELOP. THESE STORMS
MOVE INTO CENTRAL AND SOUTH CENTRAL KANSAS BY MIDNIGHT WITH MOSTLY
CLEAR SKIES OBSERVED. WINDS WILL GENERALLY BE FROM THE SOUTH
SOUTHEAST AT 15 TO 20 KNOTS THIS AFTERNOON INTO TONIGHT GUSTING TO
AROUND 25 KNOTS AT TIMES. HIGHER GUSTS WILL BE POSSIBLE UNDER AND
AROUND THUNDERSTORMS.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  90  60  82  53 /  60  40  30  20
GCK  90  58  79  52 /  30  20  30  20
EHA  95  57  80  52 /  10  10  20  20
LBL  95  58  83  52 /  10  10  20  10
HYS  88  63  79  54 /  60  60  40  30
P28  88  65  86  58 /  60  60  20  20

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM CDT /8 PM MDT/ THIS EVENING FOR
KSZ061-062-074-075-084-085.

&&

$$

SHORT TERM...JJOHNSON
LONG TERM...RUTHI
AVIATION...HOVORKA_42