500
FXUS64 KLUB 131139
AFDLUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
639 AM CDT TUE AUG 13 2013
.AVIATION...
A COLD FRONT MOVING THROUGH THE AREA WILL BRING A N-NE WIND SHIFT
TO KLBB BY ABOUT 13Z...FOLLOWED BY PREVAILING E-NE WINDS AT BOTH
TERMINALS THROUGH THE REMAINDER OF THE FCST. SCATTERED SHOWERS AND
THUNDERSTORMS MAY AFFECT EITHER/BOTH TERMINALS THIS AFTERNOON AND
EVENING AND WE HAVE A PROB30 MENTION AT BOTH. THE SHOWER ACTIVITY
MAY CONTINUE OVERNIGHT BUT WITH LOW CONFIDENCE IN THE PARTICULARS.
ALSO...THERE IS SOME INDICATION THAT LOW CEILINGS NEAR OR BELOW
2000 FT MAY DEVELOP AT EITHER TERMINAL...MORE LIKELY AT KCDS. WE
WILL LEAVE MENTION OUT OF TAF FOR NOW UNTIL THERE IS A STRONGER
INDICATION.
&&
.PREV DISCUSSION... /ISSUED 419 AM CDT TUE AUG 13 2013/
SHORT TERM...
INITIAL OUTFLOW BOUNDARY MOVED THROUGH MOST OF THE AREA LAST NIGHT
WITH WEAK EASTERLY WINDS NOTED ACROSS ALL BUT THE SW SPLNS...WHERE
WINDS REMAINED SOUTHERLY. WE/VE SEEN SOME MORNING SHOWER ACTIVITY
CROP UP JUST WEST OF THE STATE LINE AS WE CONTINUE TO SEE SOME WEAK
UPPER-AIR RIPPLES ROTATE AROUND A VERY FLAT RIDGE CENTERED OVER SW
TX. FARTHER TO THE NORTH...A W-E BAND OF MORE WIDESPREAD SHOWERS AND
THUNDERSTORMS STRETCHED ACROSS THE NRN TX PANHANDLE WITH A
WELL-DEFINED OUTFLOW/COLD FRONT BOUNDARY MOVING SOUTH...APPROACHING
KAMA AT 3 AM. THIS BOUNDARY SHOULD MOVE INTO OUR NRN ZONES EARLY
THIS MORNING...AND POSSIBLY FARTHER SOUTH BEFORE LOSING MOMENTUM.
SURFACE WINDS WILL BECOME FAIRLY LIGHT ACROSS THE AREA
TODAY...LIKELY WITH A SMALL NORTH TO EAST COMPONENT. THIS SHOULD
MAINTAIN HEALTHY MOISTURE IN PLACE IN THE LOW-LEVELS. ALOFT...WATER
VAPOR IMAGERY THIS MORNING SHOWS A SHORTWAVE LIFTING NORTH ACROSS
THE GREAT BASIN...ANOTHER SWINGING SOUTH THROUGH THE DAKOTAS...WITH
CONVOLUTED FLOW IN-BETWEEN THESE TWO SYSTEMS FROM THE SRN ROCKIES
INTO THE HIGH PLAINS. AN UPPER-LVL JET WILL ADVANCE INTO SRN CO/KS
TODAY...WITH A BELT OF 30+ KT MID-LVL WINDS DEVELOPING ACROSS NE NM
TO WRN OKLA THIS AFTERNOON...AND SPREADING INTO THE NRN SPLNS TO RED
RIVER VALLEY TONIGHT. LIFT WITH THE JET WILL COUPLE WITH LOW-LVL
LIFT IN THE FRONT/OUTFLOW ZONE AND A MODERATELY UNSTABLE AIRMASS TO
SUPPORT CONVECTIVE CHANCES THROUGH THE DAY AND ON INTO THE NIGHT.
HIGH-RES GUIDANCE SUGGESTS THAT THE ACTIVITY IN THE PANHANDLE WILL
SAG SOUTH INTO OUR NRN ZONES THIS MORNING AND WEAKEN. THEN THIS
AFTERNOON...WE SHOULD SEE SCATTERED CONVECTIVE DEVELOPMENT PRIMARILY
ACROSS THE NW PORTIONS OF THE SPLNS AND SWRN TX PANHANDLE...ALTHOUGH
WE CAN/T RULE OUT DEVELOPMENT ALMOST ANYWHERE. STORMS WILL GENERALLY
MOVE EAST AND WILL TAP INTO MLCAPES RUNNING 1000 TO 2000 J/KG AND
0-6 KM BULK SHEAR OF 30 KTS SOUTH TO 40+ KT NORTH. THIS ENVIRONMENT
WILL SUPPORT SOME SEVERE STORM POTENTIAL /MAINLY DAMAGING WIND
GUSTS/ THIS THREAT WILL BE HIGHER ACROSS THE NRN ZONES WHERE THE
SHEAR WILL BE GREATER...BUT WE WILL HAVE TO MONITOR JUST WHERE THE
OUTFLOW BOUNDARY ACTUALLY SETS UP TO ENHANCE LOW-LVL CONVERGENCE AND
LIFT. ALSO...STORM CELLS POSSIBLY TRAINING ON THE COLD SIDE OF THE
BOUNDARY COULD LEAD TO SOME LOCALLY HEAVY RAIN POTENTIAL THIS
EVENING. AS WE HEAD INTO THE OVERNIGHT HOURS...THE FORECAST
CONFIDENCE DECREASES AS BEST UPPER-LEVEL LIFT WILL REMAIN POSITIONED
ACROSS THE NORTH...BUT BEST LOW-LVL FOCUS WILL KEEP SHIFTING
SOUTH...WITH THE FRONT MOVING ON INTO THE PERMIAN BASIN BY EARLY WED
MORNING. THE BULK OF GUIDANCE KEEPS THE HIGHEST RAIN CHANCES PINNED
ACROSS THE NORTH. OVERALL COVERAGE AND STRENGTH OF ACTIVITY IS
EXPECTED TO WANE AFTER MIDNIGHT...ALTHOUGH WE WILL HAVE TO WATCH
BACK TO THE WEST WHERE A OVERNIGHT COMPLEX MAY BEGIN TO FORM NEAR
THE STATE LINE WHERE LIFT FROM NEXT SHORTWAVE STARTS TO IMPINGE ON
POST-FRONTAL UPSLOPE.
LONG TERM...
AN UNSETTLED STRETCH OF WEATHER WILL KICK OFF THE EXTENDED FORECAST
THANKS TO A PERIOD OF NORTHWESTERLY FLOW ALOFT AND A FRONTAL
BOUNDARY IN/NEAR THE AREA. HOWEVER...THE DEVIL IS IN THE DETAILS
WITH MUCH UNCERTAINTY IN THE SPATIAL AND TEMPORAL DISTRIBUTION OF
THE BEST SHOWER/STORM CHANCES RESULTING FROM UNKNOWNS REGARDING
THE EXACT FRONTAL POSITION AND TIMING OF SUBTLE SHORTWAVES MOVING
THROUGH THE FLOW ALOFT.
NORTHWESTERLY MID-LEVEL FLOW WILL BEGIN TO TAKE SHAPE ON WEDNESDAY
AS AN UPPER RIDGE AMPLIFIES OVER THE ROCKIES DOWNSTREAM OF A LARGE
VORTEX CENTERED OFF THE COAST OF BRITISH COLUMBIA. WEST TEXAS WILL
BE POSITIONED BETWEEN THE RIDGE AND LARGE-SCALE TROUGHING ACROSS THE
EASTERN PORTION OF THE CONTINENT. AT THE SFC...A FRONTAL BOUNDARY IS
PROGGED TO SETTLE SOUTHWARD THROUGH MOST IF NOT THE ENTIRE CWA EARLY
WEDNESDAY...WITH RICH POST-FRONTAL MOISTURE ADVECTING IN ON UPSLOPE
WINDS. THIS MOIST ENVIRONMENT WILL READILY SUPPORT PRECIPITATION AND
EFFICIENT RAINFALL RATES GIVEN ANY SUBTLE FORCING FOR ASCENT.
INITIALLY THE FRONTAL FORCING AND PERHAPS WEAK UPPER SUPPORT WILL
KEEP DECENT RAIN CHANCES GOING ON WEDNESDAY...WITH ADDITIONAL
CONVECTION FOCUSED ALONG AND BEHIND THE FRONT AS DAYTIME HEATING
PEAKS AND A POSSIBLE WEAK SHORTWAVE TROUGH APPROACHES. ONE
QUESTION MARK IS HOW MUCH HEATING CAN DEVELOP WEDNESDAY AFTERNOON
WITH THE NAM SUGGESTING LOW CLOUDS MAY HOLD TOUGH MUCH OF THE DAY
AND LIMIT POTENTIAL INSTABILITY. THE ECMWF AND GFS ARE MORE
OPTIMISTIC AND PROJECT SBCAPES CLIMBING TO NEAR OR IN EXCESS OF
1500 J/KG. IF THE STRONGER INSTABILITY IS REALIZED IT COULD BRING
THE POTENTIAL FOR A FEW STRONG TO SEVERE STORMS AS 0-6 KM SHEAR
CLIMBS TO AROUND 35 KNOTS. WE WILL ALSO LOOK FOR THE POSSIBILITY
OF A MCS ROLLING IN LATE FROM THE NORTH...THOUGH THE COOLER AND
MORE STABLE NAM SOLUTION DOES NOT SUPPORT THIS. FOR NOW...HAVE
MADE ONLY MINOR ADJUSTMENTS TO THE POP/WX GRIDS...MAINTAINING A
30-40 PERCENT CHANCE OF STORMS WEDNESDAY AND WEDNESDAY NIGHT. THE
OVERALL SETUP WILL NOT CHANGE MUCH THURSDAY...THOUGH THE FRONTAL
ZONE MAY RETREAT A BIT...SO THUNDER CHANCES WILL CONTINUE WITH NWP
CURRENTLY SUGGESTING ANOTHER SHORTWAVE WILL APPROACH FROM THE
NORTHWEST LATE KEEPING STORM CHANCES GOING LATE INTO THE NIGHT.
THE UPPER FLOW WILL TURN MORE NORTHERLY ON FRIDAY AS THE WESTERN
RIDGE FURTHER AMPLIFIES AND BEGINS TO EDGE EASTWARD. THIS WILL
REDUCE THE CHANCE THAT CONVECTION ORIGINATING OVER THE HIGHER
ELEVATION OF NM AND CO CAN MAKE ITS WAY TO THE SOUTH PLAINS...BUT
WITH THE RESIDUAL FRONTAL BOUNDARY STILL IN THE AREA AND A SHORTWAVE
GRAZING WEST TEXAS FROM THE EAST...HAVE MAINTAINED LOW STORM
CHANCES. DRIER AIR WILL GRADUALLY ADVECT IN ALOFT OVER THE WEEKEND
AS THE UPPER RIDGE BENDS FURTHER EASTWARD AND A DRYING TREND WILL
LIKELY ENSUE. THIS RIDGE WILL GRADUALLY BREAKDOWN LATE WEEKEND INTO
EARLY NEXT WEEK AS A TROUGH EMERGES FROM THE CENTRAL/NORTHERN
ROCKIES. THIS COULD BEND THE MONSOON MOISTURE EASTWARD...PERHAPS
REJUVENATING STORM CHANCES.
REGARDING TEMPERATURES...TENDED TO FAVOR THE COOL SIDE OF GUIDANCE
GIVEN THE EXPECTED CLOUD COVER AND RAIN IN THE AREA MID TO LATE
WEEK. TEMPERATURES WILL GRADUALLY TREND UPWARD BY THIS WEEKEND AS
THE UPPER RIDGE BENDS OVER AND SOUTHERLY LOW-LEVEL FLOW RETURNS TO
WEST TEXAS.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 86 62 84 61 86 / 30 50 40 40 30
TULIA 86 64 82 63 84 / 30 50 40 40 30
PLAINVIEW 90 65 81 64 84 / 30 40 40 40 30
LEVELLAND 92 66 84 65 88 / 20 30 40 40 30
LUBBOCK 92 68 83 66 86 / 20 30 40 40 30
DENVER CITY 93 66 88 65 91 / 20 20 40 30 30
BROWNFIELD 93 68 86 65 90 / 20 20 40 40 30
CHILDRESS 91 68 85 68 87 / 40 60 40 40 30
SPUR 95 70 86 68 89 / 20 30 40 40 30
ASPERMONT 98 72 89 69 90 / 20 30 40 40 30
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
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