Area Forecast Discussion
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FXUS64 KLUB 032048
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
348 PM CDT SUN MAY 3 2015

.SHORT TERM...
THE BENIGN WX PATTERN WE HAVE BEEN EXPERIENCING OF LATE WILL
GRADUALLY TAKE A TURN FOR THE WORSE /OR BETTER DEPENDING ON YOUR
PERSPECTIVE/....AS THE UA RIDGE THAT PROVIDED THE REGION WITH WARM
AND DRY CONDITIONS WILL CONTINUE TO SHIFT EAST AWAY FROM THE AREA
TODAY. AS SUCH...FLOW ALOFT WILL GRADUALLY BACK TO THE SOUTHWEST
THROUGH THE SHORT TERM PERIOD AND THUS A MORE UNSETTLED WX PATTERN
WILL COMMENCE TO TAKE SHAPE...WHICH HAS BEGUN LATE THIS AFTN.

SCATTERED MID-UPPER LEVEL CLOUDINESS HAS NOT TEMPERED THE WARMTH
WITH HIGHS IN THE 80S PREVAILED LATE THIS AFTN...WITH SLIGHTLY
BREEZY 10-20 MPH S-SW WIND SPEEDS. ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPED ACROSS THE HIGHER TERRAIN OF ERN NM ALONG A
SFC TROUGH/DIFFUSED DRYLINE EARLIER THIS AFTN...COURTESY OF
TOPOGRAPHIC EFFECTS AND MORE IMPORTANTLY THE PRESENCE OF A WEAK
EMBEDDED UA SHORTWAVE. DEWPOINTS HAVE DROPPED INTO THE 30S AND 40S
ACROSS THE WRN SOUTH PLAINS PER 20Z METARS /VERSUS 40S AND 50S
EARLIER THIS MORNING/...WHICH SUGGESTS THAT THE DIFFUSED DRYLINE HAS
COMMENCED TO SHIFT EWRD TO ACROSS THE WRN ZONES. AS SUCH...THE
ISOLATED THUNDERSTORM ACTIVITY HAS SHIFTED TO ACROSS THE FAR WESTERN
AND NORTHWESTERN SOUTH PLAINS. THIS IS ROUND ONE OF PRECIP ACTIVITY.
A DRY SUB-CLOUD LAYER HINTS AT THIS PRECIP ACTIVITY BEING HIGH-BASED
SO THE THREAT OF THIS ACTIVITY BECOMING EFFICIENT RAINMAKERS IS
LOW...THOUGH MUCAPE OF 300-600 J/KG...STEEPENED LAPSE RATES /AND
RATHER WEAK SHEAR/ DOES SUPPORT THE POTENTIAL FOR STRONG TO POSSIBLY
SEVERE GUSTS AND PERHAPS SMALL HAIL. MODEL SOLUTIONS CONFINE THE
MAJORITY OF THE ACTIVITY THIS AFTN-EVENING TO LOCALES ON THE
CAPROCK...BECAUSE THE FARTHER EAST YOU GO...THE BETTER THE CIN AND
THE MORE HARD-PRESSED STORMS CAN BE MAINTAINED/DEVELOP.

TONIGHT...THE DRYLINE WILL RETREAT TO ERN NM AND THE S-SE UPSLOPE
SFC FLOW WILL FILTER IN BETTER LOW LEVEL MOISTURE /PWATS INCREASING
TO 0.80-1.00 INCH/...AND THUS THE POTENTIAL FOR THE DEVELOPMENT OF A
STRATUS DECK /AND MAYBE LIGHT FOG/. FURTHERMORE...THIS UPTICK IN
MOISTURE COUPLED WITH LINGERING INSTABILITY AND A 20-30 KT NOCTURNAL
LLJ COULD AID IN PROLONGING SHOWERY ACTIVITY /MAINLY ACROSS THE
CAPROCK/ AFTER MIDNIGHT. THE CLOUD COVER AND INCREASED MOISTURE WILL
RESULT IN MILD OVERNIGHT TEMPS WITH LOWER 50S ACROSS THE SW TX
PANHANDLE TO THE LOWER 60S ELSEWHERE EXPECTED.

ROUND TWO OF STORMS WILL TAKE PLACE MONDAY LATE MORNING-AFTN...AS A
PACIFIC UA DISTURBANCE APPROXIMATELY 600 MILES WEST OF KLAX LATE
THIS AFTN...TRANSLATES TO ACROSS SWRN AZ LATE MONDAY AFTN AND
PROMOTE 500 MB AND SFC HEIGHT FALLS...WHICH WILL LEAD TO THE DRYLINE
REMAINING WEST OF THE CWA AND THUS IMPROVING LOW LEVEL MOISTURE
/PWATS INCREASING TO 0.90-1.10 INCHES/. AHEAD OF THE MAIN UA
LOW...MODEL SOLUTIONS EXHIBITED A LEAD SHORTWAVE MOVING IN FROM THE
SOUTHWEST LATE MONDAY MORNING/AFTN...SO IT IS NO SURPRISE TO SEE
BEST QPF SIGNALS INITIALIZING ACROSS THE SWRN AND WRN ZONES DURING
THE SAID TIME PERIOD. WITH THE AMOUNT OF AVAILABLE
MOISTURE...MODERATE RAINFALL WILL BE POSSIBLE AS HINTED AT BY THE
WEATHER PREDICTION CENTER...HOWEVER THAT IS NOT THE ONLY THREAT WE
NEED TO BE CONCERNED ABOUT. ALTHOUGH HIGH TEMPS ON MONDAY WILL BE
COOLER THAN RECENT DAYS /70S/ GIVEN INCREASED CLOUD COVER AND
RAINFALL POTENTIAL...TEMPS WILL BE COOLER ALOFT AND STEEPENED LAPSE
RATES WILL BECOME REALIZED. COUPLE THIS WITH VEERING WIND
PROFILES...NEGLIGIBLE CIN AND 30-40 KTS OF 0-6 KM BULK SHEAR
/ESPECIALLY ACROSS THE FAR WRN AND SWRN ZONES/ COULD LEAD TO A FEW
STORMS BECOMING STRONG TO SEVERE WITH HAIL AND GUSTY WINDS BEING THE
PRIMARY THREATS. PRECIP WILL GRADUALLY EXPAND NORTH AND EAST INTO
MONDAY EVENING...WHICH WILL BE DISCUSSED IN MORE DETAIL IN THE LONG
TERM DISCUSSION BELOW. /29

.LONG TERM...
A HEAVY RAIN THREAT EARLY IN THE WEEK IS STILL ON TARGET WITH AN
IMPULSE PASSING MONDAY EVENING IN ADVANCE OF A MORE NOTABLE UPPER
TROUGH SWINGING BY JUST TO OUR WEST/NORTHWEST TUESDAY. MOISTURE
WILL MAXIMIZE DURING THIS PERIOD TO AROUND 1.0-1.4 INCHES OF
PRECIPITABLE WATER...ROUGHLY DOUBLE AVERAGE. LACK OF SURFACE
BOUNDARY MONDAY NIGHT PRECLUDES US HAVING CONFIDENCE FOR A FLASH
FLOOD WATCH AT THIS TIME...THOUGH NOTED THAT THE WRF/NAM REMAINS
CONSISTENT WITH A HEAVY RAIN MAXIMUM YET AGAIN FROM THE SOUTHWEST
PANHANDLE INTO THE CENTRAL PANHANDLE. OTHER SOLUTIONS ARE LESS
CONSISTENT THOUGH INDICATE RAIN MAXIMUMS FURTHER SOUTH IN VARIOUS
PARTS OF OUR AREA. TUESDAY ASSUMING ACTIVITY CLEARS EARLY IN THE
DAY WILL LEAVE PLENTY OF OPPORTUNITY FOR SURFACE HEATING OVER
PARTS OF THE AREA...WRF/NAM SHOWS AROUND 2000 JOULES PER KILOGRAM
OF SURFACE BASED CAPE OVER WESTERN ZONES...WHILE BULK SHEAR
INCREASES TO THE RIGHT AND IN ADVANCE OF A MID LEVEL WIND MAX
SWINGING INTO WEST TEXAS. THIS SYSTEM TUESDAY ALSO MAY TIGHTEN
SURFACE GRADIENT ENOUGH TO PULL DRYLINE BACK AGAINST THE STATE
LINE AND COULD LEAD TO FAIRLY INTENSE THUNDERSTORMS...AGAIN
ASSUMING WE SEE ENOUGH SURFACE WARMING. ANOTHER POSSIBILITY
HOWEVER COULD BE THAT WITH A WEAKLY CAPPED ENVIRONMENT...SHOWERS
AND THUNDERSTORMS COULD MORE OR LESS CONTINUE THROUGH TUESDAY
MORNING AND VASTLY UPEND THE ABILITY TO GENERATE MUCH CAPE THOUGH
SHEAR WILL OBVIOUSLY BE GOOD AND LIFTED CONDENSATION LEVELS ALSO
FAIRLY LOW. SO...WE STILL FEEL THERE IS A VALID THREAT FOR SEVERE
STORMS DEVELOPING DURING THIS TIME AS WELL. AND TUESDAY COULD BE A
MORE VALID FLASH FLOOD RISK.

PLENTY GOING ON THROUGH TUESDAY...PRECIPITATION SHIELD SHOULD BE
MOVING NORTHEAST TUESDAY NIGHT AND MIGHT BE FOLLOWED BY FAIRLY
DEEP DRYING ACROSS NORTHWEST ZONES ANYWAY HEADING INTO WEDNESDAY
AS ANTICYLONIC CURVATURE BRIEFLY FOLLOWS. UPPER FLOW ALREADY WILL
BEGIN TO BACK BY LATE WEDNESDAY HOWEVER...AND WE STILL DONT THINK
MOISTURE WILL BE TOTALLY SCOURED OUT SO ARE RETAINING LOW CHANCES
MAINLY EAST. BY THURSDAY AND BEYOND UPPER FLOW SHOULD BE
RECOVERING AS NEXT UPPER TROUGH TAKES SHAPE IN THE SOUTHWEST. WE
HAVE RETAINED MODEST THUNDER CHANCES INTO AND THROUGH THE NEXT
WEEKEND. RMCQUEEN

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        55  75  54  69 /  30  60  80  80
TULIA         58  76  57  69 /  30  30  80  80
PLAINVIEW     59  75  57  70 /  30  30  80  80
LEVELLAND     60  75  57  73 /  40  40  80  70
LUBBOCK       61  76  58  72 /  20  30  80  70
DENVER CITY   59  76  57  76 /  30  40  80  50
BROWNFIELD    60  76  58  74 /  30  40  80  60
CHILDRESS     62  80  61  72 /  10  20  70  80
SPUR          60  77  59  71 /  10  20  70  80
ASPERMONT     62  79  62  74 /  10  20  60  70

&&

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

$$

29/05



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