Area Forecast Discussion
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663
FXUS64 KLUB 190454
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
1154 PM CDT MON MAY 18 2015

.AVIATION...
CONVECTION ONCE AGAIN TRYING TO DEVELOP SW OF KLBB TERMINAL.
PROSPECTS FOR THIS ROUND MORE PROMISING AS 30-40KT LLJ FEEDS
MOISTURE NORTHWARD ALONG EXPANDING OUTFLOW/WARM FRONTAL FEATURE.
ADDITIONAL LIFT ASSOCIATED WITH SHORTWAVE TROUGH ENTERING THE
EASTERN PLAINS OF NM WILL HELP SUSTAIN AND BROADEN CONVECTION
OVERNIGHT. WITH UPSLOPE FLOW...MOISTENING PROFILE AND PROSPECTS
FOR WIDESPREAD CONVECTION KEPT IFR CIGS IN PLACE FOR ALL TAF SITES
WITH INTERMITTENT TSRA. SUBSIDENCE BEHIND EXITING WAVE SHOULD
BEGIN TO WIN OUT AFT 18Z FROM W-E BUT HAVE KEPT MVFR CIGS THROUGH
TAF CYCLE GIVEN PERSISTENT UPSLOPE AND LACK OF WHOLESALE DRYING.

&&

PREV DISCUSSION... /ISSUED 429 PM CDT MON MAY 18 2015/

SHORT TERM...

.THREAT FOR FLOODING TO DEVELOP TONIGHT THROUGH TUESDAY MORNING...

MID-AFTERNOON SURFACE ANALYSIS DEPICTED BROAD E-SE FLOW ACROSS THE
SOUTHERN HALF OF THE CWA AHEAD OF A WEAK AND DECAYING COLD FRONT
STRETCHING FROM MULESHOE TO CAPROCK CANYONS STATE PARK. WINDS BEHIND
THIS FRONT HAD ALREADY VEERED MORE EASTERLY SINCE THIS MORNING IN
RESPONSE TO LOWER PRESSURES IN EASTERN NM...SO THE UPSHOT OF THIS IS
THAT A RESERVOIR OF GULF MOISTURE WILL CONTINUE FEEDING INTO THE
REGION TONIGHT FREE OF INTERRUPTIONS. THIS MOISTURE HAS ALREADY BEEN
ASCENDING NWD ATOP THE REGION AS CONFIRMED BY SOME ACCAS AND MID-
LEVEL VIRGA AT TIMES...BUT FARTHER SOUTH AND SOUTHWEST LIES BETTER
LL MOISTURE AND SUBSEQUENTLY HIGHER CAPE. MODEL CONSENSUS IS FOR
SCATTERED TSTORMS TO DEVELOP FROM THE DAVIS MOUNTAINS NWD TO AROUND
LEA COUNTY AND SPREAD NE THIS EVENING. BEST THREAT FOR SEVERE STORMS
STILL LOOKS TO FAVOR AREAS TO OUR S-SW WHERE MOISTURE WILL BE
COMPARABLY DEEPER...BUT A FEW SEVERE MODES MAY SURVIVE THEIR JOURNEY
NORTHWARD INTO LOWER CAPE BEFORE TRANSITIONING MORE TOWARD NON-
SEVERE STORMS.

ALTHOUGH LOCALLY HEAVY RAIN WILL OCCUR WITH SOME STORMS THIS
EVENING...OUR GREATEST CONCERN LIES IN THE OVERNIGHT HOURS THROUGH
TUESDAY MORNING WHEN ISENTROPIC ASCENT ACCELERATES IN ADVANCE OF A
LEAD TROUGH AND IMPROVED SWLY CYCLONIC FLOW. DEEP SELY FLOW UP TO
700MB WILL ADVECT A SURGE OF PWATS BETWEEN 1.3 AND ALMOST 2 INCHES
OVER MUCH OF THE REGION. GREATEST FOCUS FOR WRINGING OUT THIS
MOISTURE WILL BE A 35 KNOT SELY LLJ AND A DEVELOPING WARM FRONT
ACROSS THE NRN PERMIAN BASIN...PERHAPS AIDED/ENHANCED BY CONVECTIVE
OUTFLOWS TO ITS NORTH. WPC FAVORS THIS THINKING AND HAS TRENDED
HEAVILY TOWARD THE GFS /WHICH PROVED ACCURATE TWO WEEKS AGO IN A
SIMILAR FLOOD SETUP IN LYNN COUNTY AND SURROUNDING AREAS/...SO WE
HAVE OPTED FOR AN AREAL FLOOD WATCH FOR OUR SOUTHERN TWO ROWS OF
COUNTIES THRU NOON TUESDAY AT WHICH POINT THE DEPARTING IMPULSE AND
VEERING LLJ WILL CARRY THE BRUNT OF PRECIP EAST OF THE REGION.

IN THE WAKE OF THESE STORMS...COOL/MOIST SELY FLOW COULD GREATLY
LIMIT THE EXTENT OF AFTERNOON DESTABILIZATION AHEAD OF A DRYLINE IN
ERN NM. THIS CONCERN IS CITED BY SPC...HOWEVER DRIER MID-LEVEL AIR
BEHIND THE LEAD IMPULSE WILL GARNER STEEPER LAPSE RATES AT THE
EXPENSE OF SOME SUBSIDENCE. WE DID SIDE WITH A MORE WESTERLY DRYLINE
LOCATION BY MID-AFTERNOON SIMILAR TO THE GFS GIVEN LIKELY CONVECTIVE
OUTFLOWS IMPEDING THE DRYLINE/S EASTWARD PROGRESS. AT THE VERY LEAST
THERE SHOULD BE A NARROW CORRIDOR OF DECENT CAPE SUPPORTIVE FOR
SEVERE STORMS...BUT THE OVERALL COVERAGE OF SUCH MAY BE TEMPERED
HEAVILY BY LIMITED BACKGROUND ASCENT. ANY STORMS THAT DO DEVELOP
WILL BE IN A FAVORABLY SHEARED ENVIRONMENT FOR SUPERCELLS COMPLETE
WITH AN ATTENDANT THREAT FOR TORNADOES GIVEN LOW LCL AND LFC
HEIGHTS. MAX TEMPS WERE COOLED OFF BY SEVERAL DEGREES MAINLY IN OUR
EASTERN COUNTIES WHERE MORNING PRECIP AND THICK STRATUS WILL BE MOST
PREVALENT.

LONG TERM...

LONG TERM FORECAST REMAINS ON TRACK FOR AN EXTENDED PERIOD OF CLOUDY
SKIES...COOLER THAN NORMAL TEMPS AND SEVERAL ROUNDS OF STRONG TO
SEVERE THUNDERSTORMS WITH PERIODS OF HEAVY RAINFALL THROUGH THE
WEEKEND.

TUESDAY OVERNIGHT INTO WEDNESDAY WILL FEATURE WIDESPREAD RAINFALL
FROM EARLIER IN THE DAY TUESDAY BEGINNING TO TAPER OFF AS THE FIRST
WAVE EXITS NORTHEAST WHILE SWEEPING A COLD FRONT SOUTH THROUGH THE
TEXAS PANHANDLE THROUGH EARLY MORNING HOURS AND THE SOUTH/ROLLING
PLAINS BY EARLY WEDNESDAY AFTERNOON. COOLER AIR BEHIND THE FRONT WILL
HELP LIMIT INSTABILITY SOMEWHAT LESSENING THE POTENTIAL FOR
THUNDERSTORMS LATER IN THE AFTERNOON/EVENING REACHING SEVERE
LEVELS...BUT GIVEN PWATS STEADILY REMAINING BETWEEN 1.0 AND 1.5
INCHES WITH STEEP LAPSE RATES AND DECENT ELEVATED CAPE CANNOT RULE
OUT SOME MARGINALLY SEVERE HAIL OR WIND GUSTS WITH STRONGEST STORMS
ESPECIALLY ALONG THE RETREATING DRYLINE.

SOUTHEAST UPSLOPE SURFACE FLOW RETURNS OVERNIGHT WEDNESDAY INTO
THURSDAY AS THE UPPER LEVEL LOW APPROACHES FROM THE WEST. DEEP
BOUNDARY LAYER MOISTURE WILL BACK THE DRYLINE UP AGAINST THE
MOUNTAINS IN NEW MEXICO AS BAROCLINIC INSTABILITY ASSOCIATED WITH
STRONG WAVE LEADS TO ENHANCED ISENTROPIC LIFT ACROSS EASTERN NEW
MEXICO. WIDE SPREAD RAIN WITH EMBEDDED THUNDERSTORMS WILL
PROGRESSIVELY MIGRATE OUT OF NEW MEXICO INTO WEST TEXAS THROUGHOUT
THE DAY AND NIGHT ON THURSDAY.

AS THE UA LOW MARCHES NORTHEAST FOR FRIDAY WE WILL SEE MORE CLASSIC
DRYLINE CONVECTION AND A TRIPLE POINT ALIGNED ACROSS THE SOUTH
PLAINS AND TEXAS/NEW MEXICO BORDER. THIS WOULD ENHANCE SEVERE
POTENTIAL ESPECIALLY IF MORE HEATING IS ALLOWED THAN CURRENTLY
PROGGED. FOCUS FOR THE WEEKEND SHIFTS EAST SLIGHTLY TO THE ROLLING
PLAINS AS THE SYSTEM SLOWLY PROGRESSES NORTHEAST. STRONG TO SEVERE
TSTORMS WITH MORE HEAVY RAIN CANT BE RULED OUT IN OUR AREA OVER THE
WEEKEND BUT SHOULD BE MORE FOCUSED ON THE EASTERN HALF OF THE
FORECAST AREA.

WORTH NOTING THAT WPC GUIDANCE HAS A LARGE SWATH OF 5 INCHES TO 7
INCHES OF RAIN BY THIS TIME NEXT WEEK WHICH WOULD BREAK THE ALL TIME
RECORD FOR MAY RAINFALL SET IN 1941 WITH MORE THAN A WEEK LEFT IN
MAY 2015. WITH MODELS HINTING TOWARD ANOTHER LARGE TROUGH/UA FOR
NEXT WEEK...PUTTING THE ALL TIME RAINFALL RECORD FOR ANY GIVEN MONTH
.13.93 INCHES IN SEPTEMBER OF 1936...IN SIGHT...TRY TO STAY DRY.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        58  73  51  71 /  90  80  20  10
TULIA         59  70  56  70 /  90  80  30  20
PLAINVIEW     60  71  58  72 /  90  90  30  20
LEVELLAND     61  75  58  77 /  90  90  20  20
LUBBOCK       61  72  61  76 /  90  90  20  20
DENVER CITY   62  81  60  81 /  90  60  20  20
BROWNFIELD    62  77  61  80 /  90  90  20  20
CHILDRESS     63  69  63  73 /  60 100  50  30
SPUR          64  71  64  75 /  80 100  30  40
ASPERMONT     66  74  66  81 /  70 100  50  40

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR TXZ033>044.

&&

$$

24/99/



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