Area Forecast Discussion
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FXUS64 KLUB 271738 AAA
AFDLUB

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LUBBOCK TX
1238 PM CDT WED MAY 27 2015

.UPDATE...
THE LATEST OBSERVATIONAL AND MODEL DATA SUPPORT A RISK OF SEVERE
T-STORMS THIS AFTERNOON AND EVENING. THE DRYLINE RETREATED INTO NM
THIS MORNING...AND IS EXPECTED TO MOVE ONLY AS FAR EAST AS THE
WESTERN SOUTH PLAINS THIS AFTERNOON. EAST OF THE DRYLINE...STRONG
INSTABILITY WILL DEVELOP WITH SURFACE TEMPS WARMING INTO THE
MIDDLE 80S AND RELATIVELY COOL TEMPS ALOFT /ALTHOUGH THERE IS
PRONOUNCED WARM LAYER JUST ABOVE 850 MB/. SURFACE FLOW IS
EXPECTED TO REMAIN BACKED ACROSS THE SE TX PANHANDLE...WHICH MAY
PROVIDE A FOCUS FOR T-STORM DEVELOPMENT THIS AFTERNOON IN THE
VICINITY OF THE CAPROCK ESCARPMENT. MORE ISOLATED DEVELOPMENT IS
POSSIBLE ALONG THE DRYLINE. ALTHOUGH MID-LVL FLOW /20-30 KTS AT
500 MB/ AND DEEP-LAYER SHEAR ARE ONLY MARGINAL FOR STORM
ORGANIZATION...IMPRESSIVE CAPE VALUES OF 2000-3000 J/KG WILL
SUPPORT SEVERE HAIL AND WIND. WE ALSO CAN/T RULE OUT AN ISOLATED
TORNADO...MAINLY IN THE FAR SE TX PANHANDLE WHERE EHI AND LCL
VALUES WILL BE MORE SUPPORTIVE. PROJECTED SUPERCELL MOTION IS TO
THE E-SE AT A MEAGER 5-10 KTS...WHICH WILL BRING A LOCALLY HEAVY
RAIN/FLOODING THREAT AS WELL. NEGATIVE FACTORS INCLUDE LITTLE IF
ANY LARGE-SCALE ASCENT...AND SURFACE HEATING THAT MAY NOT QUITE BE
SUFFICIENT TO BREAK THE CAP WITHOUT AIDE FROM BOUNDARIES. THIS MAY
LEAD TO ACTIVITY REMAINING ISOLATED...AT LEAST UNTIL STRONGER
ASCENT ARRIVES TONIGHT.

&&

.AVIATION...
VFR CONDITIONS SHOULD PREVAIL AT ALL TERMINALS THROUGH 21 UTC OR
SO...BUT WE HAVE LOW CONFIDENCE IN CONDITIONS BEYOND THAT DUE TO
POSSIBLE T-STORM ACTIVITY. T-STORM CHANCES WILL BE HIGHEST AT
KCDS. T-STORM ACTIVITY WILL BE MAINLY 21 UTC THROUGH 04 UTC...BUT
MORE ISOLD ACTIVITY MAY CONTINUE OVERNIGHT AS WELL. LOW
CEILINGS...POSSIBLY BELOW MVFR...ARE ALSO POSSIBLE AT ALL
TERMINALS LATE TONIGHT AND EARLY THURSDAY MORNING...BUT THERE IS
LARGE UNCERTAINTY IN TIMING THE ONSET AND DURATION OF CATEGORY
REDUCTIONS.

&&

.PREV DISCUSSION... /ISSUED 450 AM CDT WED MAY 27 2015/

SHORT TERM...
LARGE SCALE FEATURES TODAY DOMINATED BY TENDENCY FOR WEAK
ANTICYCLONIC CURVATURE/RIDGING WHICH SHOULD BE A THUNDER NEGATIVE
FOR MUCH OF THE AREA. BY TONIGHT THE NEXT UPPER TROUGH STEERING EAST
INTO ARIZONA AND SONORA SHOULD INITIATE BACKING UPPER FLOW AND
INCREASE IN UPPER DIVERGENCE WHICH WOULD BE A POSITIVE. BUT NET
RESULT OF OUTFLOWS FROM FOUR NEARBY CONVECTIVE SYSTEMS THIS MORNING
MIGHT REVERSE THAT TREND TODAY AT LEAST ACROSS THE ROLLING PLAINS
WHICH RESIDES MOST DIRECTLY IN-BETWEEN THE FOUR. MOISTURE LEVELS
ALSO WILL IMPROVE ALL AREAS...INCLUDING SURFACE DEWPOINTS IN THE MID
TO UPPER 60S ESPECIALLY ROLLING PLAINS. ARRIVAL OF ONE OR MORE
OUTFLOW BOUNDARIES MIGHT BE ENOUGH TO GENERATE THUNDERSTORMS BY
MIDDAY ROLLING PLAINS. CANT TOTALLY RULE OUT THUNDER BACK WEST ON
THE CAPROCK BUT WILL BE MORE DIFFICULT MORE DIRECTLY BENEATH UPPER
RIDGE AXIS AND SLIGHTLY LESS MOISTURE. FOR TONIGHT...NET WESTWARD
MOTION OF OUTFLOWS TOWARDS THE IMPROVING DYNAMIC ENVIRONMENT MIGHT
SUPPORT FAVORED ZONE CENTRAL INTO EAST...THOUGH NET INTERPLAY OF
COMPLEX OUTFLOWS NOT SO CLEAR OR SIMPLE. RECENT TENDENCY TO DEVELOP
NOCTURNAL MESO-SCALE CONVECTIVE SYSTEMS WITH MODEST SHEAR AND HIGH
INSTABILITY SEEM REASONABLE...BUT CONFIDENCE ON ONE SOLUTION VS
ANOTHER JUST NOT THERE TO ANGLE BEST AREA AND PERHAPS MOST RAINFALL
TOO MUCH ONE WAY OR ANOTHER. RMCQUEEN

LONG TERM...
COMPLEX CONVECTIVE EVOLUTION MENTIONED IN THE SHORT TERM WILL HAVE A
PROFOUND IMPACT ON WHAT OCCURS THURSDAY ACROSS THE REGION. UPPER
LIFT WILL BE ON THE INCREASE COME DAYBREAK AHEAD OF A SHORTWAVE
TROUGH MOVING OUT OF THE DESERT SOUTHWEST. WHILE A DIFFUSE DRYLINE
WILL EXIST...A SURFACE LOW WELL BACK INTO NEW MEXICO MAY KEEP IT
WEST OF THE STATE BORDER. NONETHELESS...SURFACE BOUNDARY FOCUS
WILL BE DEFINED BY CONVECTIVE OUTFLOWS FROM OVERNIGHT/EARLY
MORNING ACTIVITY. ROUGHLY 30-40 KNOTS OF 0-6 KM SHEAR WILL BE
CAPABLE OF SUPPORTING SEVERE STORMS...BUT WILL HAVE TO ASSESS THE
THERMODYNAMIC ENVIRONMENT FOLLOWING WHAT MATERIALIZES TONIGHT
REGARDING THE DEGREE OF INSTABILITY. AFTERNOON RECOVERY BEGINNING
TO LOOK MORE AND MORE IMPRESSIVE IN NWP SOLUTIONS WITH CAPES
RAMPING UP INTO THE 3-4 KJ/KG RANGE. HAVE LEFT LIKELY POPS INTACT
FOR ALL BUT THE SOUTHEAST ROLLING PLAINS THROUGHOUT THE DAY
THURSDAY WHILE SHIFTING THESE EAST INTO THE EVENING AS LIFT
APPROACHES FROM WEST TO EAST. WILL HOPEFULLY BE ABLE TO MAKE
BETTER REFINEMENT AS TO THE AREA WITH THE GREATEST THREAT FOR
DEVELOPMENT...INCLUDING SEVERE...ONCE THIS EVENING/TONIGHT
BECOME CLEARER. IF THE ABOVE MENTIONED INSTABILITY CAN DEVELOP
DOWNSTREAM OF THE UPPER FORCING AND ALONG A MESOSCALE
BOUNDARY...STEEP LAPSE RATES WILL SUPPORT UP TO BASEBALL SIZE
HAIL ALONG WITH STRONG/SEVERE DOWNBURST WIND GUSTS AND AN
ATTENDANT TORNADO THREAT NEAR ANY BOUNDARIES.

SUBSIDENCE WILL LIKELY SHUT THINGS DOWN FOR A PERIOD FRIDAY BEFORE
WHAT LOOKS LIKE A BETTER DEFINED DRYLINE WILL BE ABLE TO SPARK
ISOLATED TO SCATTERED STORMS. FOCUS WILL THEN SHIFT TO AN
APPROACHING COLD FRONT AHEAD OF ANOTHER UPPER TROUGH MOVING OUT OF
THE ROCKIES INTO THE PLAINS FRIDAY EVENING BRINGING ANOTHER GOOD
BET FOR SHOWERS AND STORMS. MOIST ISENTROPIC LIFT WILL OCCUR FOR
A PERIOD INTO SATURDAY BEFORE COOLER SURFACE RIDGING FILTERS IN
FROM THE NORTH...LEADING TO TEMPERATURES MAINLY IN THE 70S THIS
WEEKEND...AND BEGINS TO DRY THE SOUTH PLAINS REGION OUT INTO
SUNDAY AHEAD OF AN APPROACHING RIDGE.

THIS RIDGING ALOFT SHOULD BRING AT LEAST A TEMPORARY HALT TO STORM
CHANCES EARLY-MID NEXT WEEK WITH TEMPERATURES WARMING CLOSER TO
SEASONABLE NORMALS BY WEDNESDAY. INTERACTION OF EASTERN PACIFIC
TROPICAL SYSTEM AND RENEWED WESTERN CONUS ENERGY WILL BE THE NEXT
PLAYER IN APPRECIABLE SHOWER/STORM CHANCES LATER NEXT WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        58  79  54  82 /  40  60  30  20
TULIA         60  78  58  81 /  50  60  40  20
PLAINVIEW     62  78  60  81 /  50  60  40  20
LEVELLAND     63  79  60  86 /  40  60  40  20
LUBBOCK       63  79  61  83 /  50  60  50  20
DENVER CITY   65  80  61  87 /  40  60  40  10
BROWNFIELD    64  81  60  86 /  40  60  40  20
CHILDRESS     64  80  62  80 /  50  60  50  40
SPUR          62  79  62  81 /  50  60  50  30
ASPERMONT     66  81  64  84 /  40  50  60  40

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

33


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