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000
FXUS63 KDDC 170510
AFDDDC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
1210 AM CDT FRI MAY 17 2013

...UPDATE TO AVIATION...

.SYNOPSIS...
ISSUED AT 1100 PM CDT THU MAY 16 2013

WV IMAGERY AND 00Z UPPER AIR ANALYSIS INDICATE AN UPPER LEVEL
SHORTWAVE TROUGH LIFTING EAST-NORTHEAST ACROSS THE CENTRAL PLAINS
OF NEBRASKA. MEANWHILE, A WEAK UPPER LEVEL RIDGE OF HIGH PRESSURE
IS MOVING SLOWLY EAST ACROSS THE ROCKIES INTO THE WESTERN HIGH
PLAINS. NEAR THE SURFACE, MODEST LOW LEVEL MOISTURE IS ADVECTING
NORTHWEST INTO THE CENTRAL AND WESTERN HIGH PLAINS WITH SURFACE
DEWPOINTS WELL UP INTO THE 50S(F) ACROSS MUCH OF CENTRAL AND
SOUTHWEST KANSAS. THIS MOISTURE IS POOLING AHEAD OF A DRYLINE THAT
EXTENDS FROM SOUTHEASTERN COLORADO SOUTHEASTWARD INTO THE FAR
WESTERN PORTION OF THE TEXAS PANHANDLE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 338 PM CDT THU MAY 16 2013

TONIGHT:
THERE ARE TWO AREAS THAT WILL BE WATCHED THIS EVENING FOR
THUNDERSTORM THREAT. THE PRIMARY THREAT WILL BE FROM THE MENTIONED
LINE/CLUSTER OF CONVECTION (IN THE SYNOPSIS SECTION) AS IT CONTINUES
EAST-SOUTHEAST ACROSS NORTHWEST KANSAS...CLIPPING THE FAR NORTHERN
SECTION OF THE FORECAST AREA (MAINLY INTERSTATE 70). THIS WILL BE
ESPECIALLY THE CASE IF ADDITIONAL STORMS FORM FARTHER SOUTHWEST DOWN
THE LINE IN THE TRIBUNE TO GOVE AREAS EARLY THIS EVENING.  THERE
WILL BE CONTINUED SOUTHEAST WINDS PROVIDING ADEQUATE INFLOW TO
SUSTAIN CONVECTION THROUGH SUNSET ALONG WITH THE ADDITIONAL ASCENT
PROVIDED BY SHORTWAVE TROUGH JUST TO THE NORTH OF THE COMPLEX OF
STORMS. CHANCE POPS OF 30 PERCENT ARE IN THE GRIDS GENERALLY NORTH
OF HIGHWAY 96 AS A RESULT...BUT CONVECTION SHOULD BE ON A DOWNTREND
AFTER 03Z AND ESPECIALLY BY 05Z GIVEN INCREASED SURFACE-BASED
INSOLATION. CONVECTION DEVELOPING ALONG THE DRYLINE FROM SPRINGFIELD
TO LAMAR TO EADS WILL ALSO IMPACT THE FAR SOUTHWEST KANSAS COUNTIES
GENERALLY WEST OF A LAKIN TO LIBERAL LINE THROUGH 03Z.  DEEP
BOUNDARY LAYER MIXING RESULTED IN DECREASE IN DEWPOINTS DOWN INTO
THE MID TO UPPER 40S IMMEDIATELY ALONG THE COLORADO BORDER...AND
THUS CAPE IN THE 1000 TO 1500 J/KG. THIS SHOULD STILL RESULT IN
QUARTER TO PERHAPS HALF-DOLLAR SIZE HAIL IN THE STRONGEST STORM
ALONG WITH 60 MPH PEAK WIND GUSTS.  ALL CONVECTION SHOULD BE
DISSIPATED AFTER 06Z.

FRIDAY:
ANOTHER SURGE OF RICH GULF OF MEXICO AIR WILL BE COMING INTO
SOUTHWEST KANSAS FRIDAY...WITH LOWER TO MID 60S DEWPOINTS REALIZED
OVER MUCH OF SOUTHWEST AND SOUTH-CENTRAL KANSAS.  THIS WILL RESULT
IN TEMPERATURES PEAKING IN THE LOWER TO MID 80S OVER MUCH OF THE
REGION EXCEPT CLOSE TO THE DRYLINE ALONG THE COLORADO BORDER...WHERE
SOME 90 DEGREE READINGS ARE POSSIBLE.  THE INCREASED MOISTURE WILL
ALSO YIELD HIGHER CAPE ON THE ORDER OF 2500 TO 3000 J/KG...HOWEVER
THE LOWER-MID TROPOSPHERE WILL BE WARMER GIVEN THE INCREASED
SOUTHWEST MOMENTUM TRANSPORTING ELEVATED MIXED LAYER OVER THE
REGION. ISOLATED TOWERING CUMULUS SHOULD FORM ALONG THE DRYLINE IN
THE SAME GENERAL AREA OF FAR SOUTHEASTERN/EAST-CENTRAL COLORADO AS
WE ARE SEEING RIGHT NOW...HOWEVER TOMORROW THE INHIBITION TO
SURFACE-BASED CONVECTION WILL BE STRONGER IMMEDIATELY EAST OF THE
DRYLINE...AND THE TIGHT GRADIENT IN INHIBITION DOWNSTREAM FROM
INITIAL TOWER DEVELOPMENT SHOULD PREVENT DEEP MOIST CONVECTION FROM
THRIVING. THE LACK OF SUSTAINED CONVERGENCE ALONG THE DRYLINE WILL
LIKELY NOT BE ENOUGH TO OVERCOME THIS INCREASED INHIBITION...AS THE
PRIMARY JET OFF THE PACIFIC WILL STILL BE TOO FAR AWAY TO AID IN
ADDITIONAL UPWARD VERTICAL MOTION.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 222 PM CDT THU MAY 16 2013

SATURDAY:

ON SATURDAY, A NEGATIVELY TILTED UPPER LEVEL TROF WILL MOVE CLOSER TO
WESTERN KANSAS THROUGH THE EVENING. MID TO UPPER LEVEL FLOW WILL INCREASE
THROUGH THE DAY, WHICH WILL CAUSE A LEE INDUCED LOW ACROSS WESTERN KANSAS
TO DEEPEN. ASSOCIATED WITH THIS SURFACE LOW WILL BE A SHARPENING DRYLINE
BISECTING THE FORECAST AREA OF RESPONSIBILITY. RECENTLY, SOME OF THE
GLOBAL MODELS HAVE TRENDED WITH THE MESOSCALE MODELS IN KEEPING THIS
DRYLINE FARTHER WEST THAN PREVIOUSLY ADVERTISED. THE POSITION OF THE
DRYLINE IS CRITICAL BECAUSE CONVECTION SHOULD DEVELOP ALONG THIS MOISTURE
GRADIENT. DEWPOINTS IN THE UPPER 60S DEG F ARE EXPECTED EAST OF THE
DRYLINE WITH AN EXTREMELY UNSTABLE AIRMASS EXPECTED EAST OF THE DRYLINE
(4000-5000 J/KG OF SBCAPE). ONE CAVEAT TO THIS INSTABILITY AND POSSIBLE
CONVECTION IS WARM 700 HPA TEMPERATURES (12-13 DEG C). DESPITE THIS,
THERE SHOULD BE ENOUGH SYNOPTIC FORCING/DIFFLUENT/LIFT FROM AN APPROACHING
250 HPA JET AND CONVERGENCE ALONG THE DRYLINE TO INITIATE CONVECTION.
CURRENTLY, THINK THERE WILL BE TWO AREAS OF POSSIBLE CONVECTION LATE
SATURDAY AFTERNOON. ONE AREA ACROSS NW KANSAS IN ASSOCIATION WITH THE
SURFACE LOW AND BETTER UPPER LEVEL SUPPORT, AND A CONDITIONAL AREA ALONG
THE DRYLINE SOUTH AND SOUTHEAST OF DODGE CITY. 0-6 KM BULK SHEAR IS
FORECAST IN THE 20-30 KT RANGE, WHICH IS AT THE LOW END FOR SUPERCELLS.
FORECAST SOUNDINGS EAST OF THE DRYLINE DO SUPPORT THE IDEA OF SEVERE
THUNDERSTORMS WITH VERY STEEP 800-500 HPA LAPSE RATES, LOW LEVEL VEERING
OF WINDS, HIGH VALUES CAPE IN THE HAIL GROWTH ZONE (-10 TO -30 DEG
C), AND MARGINAL WIND SHEAR IN THE 6 TO 10 KM LAYER. AS FAR AS TORNADOES
ARE CONCERNED, LCL`S SHOULD BE FAIRLY HIGH IN THE WARM/HOT AND MIXED
ATMOSPHERE, SO THE OVERALL THREAT SHOULD BE LOW. THE 12Z NAM SHOWS LOW
LEVEL SHEAR INCREASING VIA A LOW LEVEL JET AND 0-3 KM SRH INCREASING
ACROSS THE SOUTHEAST ZONES AFTER 00Z SUNDAY. THIS IS REALLY A SECOND
HAND CONCERN, BUT IS SOMETHING TO WATCH AS WE GET CLOSER TO THE EVENT.
OVERALL, SATURDAY WILL PROBABLY BE ISOLATED REPORTS OF LARGE HAIL AND
DAMAGING WINDS.

IT SHOULD BE NOTED THERE IS LARGE UNCERTAINTY IN ALL THE AFOREMENTIONED
FEATURES AND EVEN IF THE CAP WILL BREAK. STAYED TUNED AS THIS IS A LOW
CONFIDENCE FORECAST AND PINPOINTING AREAS OF CONVECTION IS DIFFICULT.

THERE IS A CONCERN FOR CRITICAL FIRE WEATHER CONDITIONS IN THE WAKE
OF THE DRYLINE SATURDAY. DUE TO THE WESTWARD TREND IN THE MODELS WITH
THE DRYLINE, WILL DEFER ANY FIRE WEATHER WATCH TO LATER SHIFTS.

LASTLY, HIGHS WILL BE IN THE 80S AND 90S (HOTTEST TEMPERATURES WEST
OF THE DRYLINE) AND LOWS HEADING INTO SUNDAY MORNING WILL VERY MILD
- 60S.

SUNDAY:

THE AFOREMENTIONED UPPER LEVEL TROF WILL CONTINUE TO MOVE ACROSS THE
STATE ON SUNDAY. MODELS DIFFER AT THIS POINT. THE NAM STILL INDICATES
THE POSSIBILITY FOR CONVECTION ACROSS THE REGION. THE GFS KEEPS PRECIPITATION
JUST TO OUR EAST. THE ECMWF INDICATES SOME CONVECTION ACROSS THE NORTH
NEAR INTERSTATE 70. AT THE SFC, THE MODELS ARE DIFFERENT WITH THE DRYLINE
POSITION AS WELL. DUE TO THE UNCERTAINTY, WILL KEEP SLIGHT PRECIPITATION
VALUES IN THE GRIDS FOR NOW. WE COULD BE DRY SLOTTED/DRYLINED AND GET NOTHING
OR OUR EASTERN ZONES COULD SEE MORE THUNDERSTORM ACTIVITY IN ASSOCIATION
WITH THE DRYLINE. SEVERE WEATHER COULD STILL BE A POSSIBILITY GIVEN
THE COMBINATION OF CAPE/SHEAR FROM SOME OF THE MODELS. HIGHS WILL BE
IN THE 80S AND LOWS IN THE 50S/60S.

MONDAY AND BEYOND:

COOLER WEATHER IS EXPECTED MONDAY WITH HIGHS MAINLY IN THE 70S OR LOW
80S. SOME POST FRONTAL CONVECTION IS POSSIBLE THROUGH THE DAY BUT CONFIDENCE
IS VERY LOW. DRIER WEATHER IS EXPECTED TUESDAY ONWARDS AS THE SYNOPTIC
WAVE CONTINUES TO MOVE AWAY FROM THE REGION AND SHORTWAVE RIDGING DEVELOPS
IN THE WAKE OF THE WAVE. TEMPERATURES LOOK FAIRLY CLOSE TO SEASONAL
NORMS THROUGH THE REST OF THE PERIOD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1210 AM CDT FRI MAY 17 2013

AS RELATIVE HUMIDITY LEVELS RISE, LOW LEVEL STRATUS IS EXPECTED TO
DEVELOP ACROSS SOUTH CENTRAL KANSAS WITHIN A SOUTHEASTERLY UPSLOPE
FLOW, THEN SPREAD NORTHWESTWARD DURING THE LATE OVERNIGHT HOURS
POTENTIALLY REACHING ALL TAF SITES BY DAYBREAK. MVFR CIGS/VSBYS ARE
EXPECTED WITH ANY STRATUS THAT DEVELOPS ALONG WITH BRIEF PERIODS
OF IFR CIGS POSSIBLE TOWARD SUNRISE. THE CIGS ARE EXPECTED TO LIFT
SLOWLY BEGINNING GENERALLY AFTER 14Z WITH VFR CONDITIONS RETURNING
BY EARLY AFTERNOON. AS FOR WINDS, BROAD SURFACE HIGH PRESSURE
STRETCHING FROM THE GREAT LAKES REGION BACK INTO THE CENTRAL
PLAINS WILL CONTINUE TO INFLUENCE LIGHT SOUTHEASTERLY WINDS ACROSS
SOUTHWEST AND CENTRAL KANSAS THROUGH LATE FRIDAY MORNING WITH
SPEEDS OF 5 TO 15KT. THE WINDS WILL INCREASE UP TO 15 TO 25KT
FRIDAY AFTERNOON AS THE SURFACE TROUGH IN EASTERN COLORADO SLOWLY
STRENGTHENS.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  63  91  63  86 /  10  20  20  20
GCK  62  93  61  84 /  10  20  20  20
EHA  62  93  61  85 /  10  10  10  10
LBL  62  98  62  87 /  10  20  20  10
HYS  63  89  65  84 /  10  20  20  20
P28  65  90  67  88 /  10  20  20  20

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...JJOHNSON
SHORT TERM...UMSCHEID
LONG TERM...SUGDEN
AVIATION...JJOHNSON