Area Forecast Discussion
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FXUS64 KLUB 152006
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
306 PM CDT WED APR 15 2015

.SHORT TERM...
SEVERE THUNDERSTORM CHANCES WILL INCREASE LATE THURSDAY. SKIP TO
FINAL PARAGRAPH IN THE SHORT TERM FOR INFORMATION ABOUT THURSDAY.

SYNOPSIS...LINEAR HIGH-BASED CUMULUS FIELD WAS PERCOLATING THIS
AFTERNOON THROUGH THE SURFACE TROUGH OVER OUR WEST-NORTHWEST
COUNTIES ON THE LEADING EDGE OF HEIGHT FALLS STARTING TO OVERSPREAD
FROM THE WEST. UPPER LOW NEAR VERNAL UTAH LATE TODAY WILL SWIRL
SOUTHEAST TO NEAR THE FOUR CORNER LATE THURSDAY BEFORE BECOMING
NEARLY STATIONARY. ANOTHER ROUND OF LIFT MAY SPREAD INTO WESTERN
COUNTIES LATER TONIGHT BEFORE POSSIBLE STRONGER LIFT AND DIFLUENCE
ZONE APPROACHES LATE THURSDAY WITH AN ENERGETIC LOBE SWINGING
NORTHEAST AROUND THE EAST SIDE OF THE UPPER LOW.

THIS EVENING...MOISTURE IN THE LOWER LEVELS HAS BECOME DEPLETED AS
EXPECTED WHILE MID LEVEL MOISTURE WAS ON THE INCREASE. INSTABILITY
ON THE ORDER OF 500-1000 JOULES PER KILOGRAM WITH STEEP LAPSE RATES
OVER WESTERN COUNTIES AND THE INCREASING WIND FLOW ALOFT POINTS TO
POSSIBILITY OF ISOLATED STRONG WIND GUSTS WITH THE HIGH-BASED SHOWER
OR THUNDERSTORM ACTIVITY THIS EVENING. OUT EAST...A DRYLINE OVER THE
CENTRAL PANHANDLE MAY EDGE A LITTLE FURTHER EAST AND COULD LEAD TO
ENOUGH LOW LEVEL CONVERGENCE FOR A FEW THUNDERSTORMS TO BREAK
THROUGH EARLY THIS EVENING PERHAPS DEVELOPING AS FAR SOUTH AS HALL-
BRISCOE COUNTY AREA THOUGH WE ARE NOT YET SEEING CUMULUS IN THIS
REGION.

OVERNIGHT...WE SHOULD SEE THAT NEXT ROUND OF DYNAMIC LIFT...AND
COUPLED WITH IMPROVING LOWER LEVEL MOISTURE COULD SUPPORT AN
INCREASE IN THUNDER MAINLY AROUND OR AFTER MIDNIGHT THROUGH WESTERN
ZONES. HOW FAR THIS COULD SPREAD EAST IS UNCERTAIN BUT WE HAVE
RETAINED A LOW CHANCE OF THUNDER LATER TONIGHT FAVORING OUR CENTRAL
AND WESTERN ZONES. INSTABILITY OF 1000-1500 JOULES PER KILOGRAM
COULD SUPPORT A BETTER CHANCE FOR ISOLATED HAIL WITH THIS BATCH. WE
CANT RULE OUT AT LEAST SOME POSSIBILITY OF A MATURE COLD POOL
SPREADING CONVECTION INTO FAR EASTERN ZONES BY LATE TONIGHT.

ALSO CANT RULE OUT PATCHY LIGHT FOG LATER TONIGHT MAINLY EASTERN
ZONES BUT SURFACE FLOW EXPECTED TO BE A NOTCH OR TWO STRONGER AND
SHOULD KEEP BOUNDARY LAYER BETTER MIXED SO HAVE LEFT THIS MENTION
OUT. AND LATE THURSDAY MORNING COULD CONTINUE TO SEE CLOUD DEBRIS
AND A FEW AREAS OF SHOWERS OR THUNDER SWIRL OFF INTO EASTERN ZONES.

THURSDAY AFTERNOON...A DRY-LINE THAT MAY START OUT NEAR THE NEW
MEXICO LINE EARLIER SHOULD SURGE EAST TOWARDS CENTRAL ZONES WITH
ENOUGH LOW LEVEL CONVERGENCE TO GENERATE SOLID THUNDER CHANCES ALONG
AND IN ADVANCE FROM CENTRAL AREAS SPREADING INTO EASTERN LATE IN THE
DAY. INSTABILITY OF AT LEAST 1500 AND POSSIBLE 2500 JOULES PER
KILOGRAM WITH BULK SHEAR VALUES IN THE 25-50 KNOT RANGE INDICATE A
SOLID POTENTIAL FOR AT LEAST A FEW SUPERCELL THUNDERSTORMS. THIS
CASE ANALOGS WITH PAST SEVERE WEATHER PRODUCING EVENTS AND HAS LED
TO AN ENHANCED SEVERE THUNDERSTORM RISK AREA FOR THE CENTRAL AND
EASTERN PANHANDLE AND SOUTH PLAINS INTO THE ROLLING PLAINS FOR LATE
THURSDAY. WE ALREADY HAVE RAMPED UP WORDING IN PRODUCTS TO INDICATE
ENHANCED SEVERE RISK INCLUDING LARGE HAIL AND ISOLATED TORNADOES.
BEST TORNADO THREAT SEEMINGLY WOULD BE LATE IN THE DAY MAINLY
EASTERN ZONES WITH LOCAL LENGTHENING OF THE LOWEST HODOGRAPH REGION
AS STRONGER SOUTH-SOUTHEAST SURFACE WINDS DEVELOP. WOULD NOT BE
SURPRISED TO SEE ADDITIONAL SHIFTING OF THE DRY-LINE POSITION WITH
LATER MODEL RUNS...PERHAPS EVEN SLIGHTLY FURTHER WEST BASED ON
RECENT TRENDS RELATED TO SLOW MOVEMENT OF THE UPPER LOW. THURSDAY
WILL CERTAINLY BE A DAY TO KEEP TUNED TO THE SKY AND FORECAST.
RMCQUEEN

.LONG TERM...
THE DRYLINE ON FRIDAY WILL RETREAT WESTWARD BY THE EARLY MORNING
BEFORE SURGING EASTWARD AGAIN DURING THE AFTERNOON. THE EXTENT OF
THE RETREAT IS IN QUESTION AS THE NAM AND ECMWF DIFFER ON POSITION.
THE NAM RETREATS THE DRYLINE BACK INTO EASTERN NM WHILE THE ECMWF
ONLY BRINGS THE DRYLINE BACK TO JUST WEST OF THE EDGE OF THE
CAPROCK. REGARDLESS OF POSITION THE ROLLING PLAINS WILL HAVE THE
BEST CHANCES OF SEEING CONVECTION TRIGGERED BY THE DRYLINE FRIDAY
AFTERNOON WHERE POPS HAVE BEEN KEPT IN THE CHANCE CATEGORY WITH
SLIGHT CHANCE ALONG OUR CENTRAL COUNTIES OF THE FA. THE POTENTIAL
FOR SVR STORMS EXISTS AS MODEL SOUNDINGS ARE SHOWING CAPE UPWARDS OF
1500 J/KG...0-6 KM SHEAR OF 40-55 KTS...DRY AIR ALOFT AND INVERTED
LOW LEVEL PROFILES. THE NAME SHOWS A CLOUD DECK AT 700H WHICH COULD
INHIBIT SOME OF THE SEVERITY OF STORMS...HOWEVER IT IS UNCLEAR IF
THIS DECK WILL ACTUALLY BE PRESENT AS THE NAM IS THE MOST PERSISTENT
MODEL TO SHOW THIS. THE DRYLINE WILL PUSH EAST OF THE AREA BY FRIDAY
NIGHT AS THE CENTER OF THE APPROACHING UPPER LOW NEARS THE TX/NM
STATE LINE. THE CENTER OF THE LOW IS PROGGED TO PASS TO OUR NORTH
WHICH WILL PUT US IN A DRY SLOT WITH CHANCES OF RECEIVING WRAP
AROUND PRECIP DECREASING FOR SATURDAY AND SUNDAY. THE FRONT WILL
PUSH THROUGH ON SUNDAY COOLING TEMPS TO BELOW SEASONAL AVERAGE...MID
60S IN THE NORTHWEST TO MID 70S IN THE SOUTHEAST. NORTHWESTERLY FLOW
ALOFT WILL DOMINATE UNTIL LATE MONDAY/EARLY TUESDAY WHEN FLOW
BECOMES MORE ZONAL. THE GFS AND ECMWF BOTH AGREE FAIRLY WELL THAT
SURFACE FLOW WILL TURN TO THE EAST IN RESPONSE TO AN APPROACHING
SURFACE TROF THAT WILL AID IN PRECIP DEVELOPMENT A FEW EMBEDDED
SHORTWAVES HELP KEEP PRECIP SUSTAINED THRU WEDNESDAY AND THURSDAY.

ALDRICH

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        47  72  41  67 /  30  40  30  10
TULIA         52  71  47  69 /  30  60  40  30
PLAINVIEW     53  72  48  69 /  30  60  40  30
LEVELLAND     53  75  48  71 /  30  40  40  20
LUBBOCK       54  76  50  72 /  30  60  40  20
DENVER CITY   54  74  48  71 /  30  30  30  10
BROWNFIELD    55  76  50  72 /  30  40  40  20
CHILDRESS     56  75  55  74 /  20  60  60  50
SPUR          56  77  54  73 /  20  60  50  50
ASPERMONT     59  78  57  76 /  20  60  60  50

&&

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

$$

05/51


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