Area Forecast Discussion
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FXUS64 KLUB 291523
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
1023 AM CDT FRI MAY 29 2015

.UPDATE...
QUICK UPDATE TO SCALE BACK CLOUD COVER ON THE CAPROCK THIS MORNING
AND ALSO TO DELAY PRECIP MENTION UNTIL THIS AFTERNOON. ASIDE FROM
A STUBBORN PATCH OF STRATUS AND SOME FOG FROM SHALLOWATER TO LBB
AIRPORT...CLEAR SKIES PREVAIL OVER THE WESTERN HALF OF THE CWA
THIS MORNING BEHIND A SURFACE TROUGH WITH LIGHT NORTH WINDS. THIS
BOUNDARY SHOULD DISSOLVE AS PRESSURE FALLS TEND TO FOCUS IN
EASTERN NM THIS AFTERNOON AHEAD OF A DECENT UPPER IMPULSE. WATER
VAPOR SHOWS THIS DISTURBANCE IN WESTERN NM AT 14Z WITH A TIME OF
ARRIVAL IN OUR WESTERN COUNTIES BY LATE THIS AFTERNOON.

BEST CHANCE FOR CONVECTIVE INITIATION SHOULD FOCUS IN THE UPSLOPE
REGIME ACROSS EASTERN NM...BUT AMPLE HEATING TODAY AREA WIDE COULD
EASILY GARNER POCKETS OF BREECHABLE CINH RESULTING IN A FEW
STORMS ESPECIALLY NEAR ANY RESIDUAL LL CONVERGENCE ALONG THE
AFOREMENTIONED SURFACE TROUGH. MLCAPE VALUES AROUND 2000 J/KG AND
0-6KM BULK SHEAR OF 30 KNOTS WILL OPEN THE DOOR TO SOME SUPERCELL
STRUCTURES /ANEMIC LL SHEAR WILL DAMPEN THE TOR THREAT/...BUT OUR
CONCERN LIES IN A SEVERE MCS EVOLUTION THIS EVENING AND OVERNIGHT
AS THE BASE OF A POTENT TROUGH GLIDES THROUGH IN CYCLONIC NW FLOW.
PERSISTENT THETA-E RIDGING ACROSS THE CWA FITS THE BILL FOR HEAVY
RAIN/FLOODING PARTICULARLY AS A COLD FRONT /NOW IN EASTERN CO
AS NOTED BY STEADY PRESSURE RISES/ DROPS SOUTH AND PROVIDES SHARP
LINEAR FORCING TONIGHT.

&&

.PREV DISCUSSION... /ISSUED 557 AM CDT FRI MAY 29 2015/

AVIATION...
LOW CIGS WERE VERY PATCHY THIS MORNING ACROSS THE REGION. IF IT
DOES AFFECT A TAF SITE IT WOULD LIKELY BE ONLY FOR A BRIEF PERIOD.
A COLD FRONT MOVING THROUGH THIS AFTERNOON AND EVENING WILL
COMBINE WITH AN UPPER LEVEL DISTURBANCE TO CREATE SHOWERS AND
THUNDERSTORMS AT ALL TAF SITES. PRIMARY ACTIVITY FROM STORMS WILL
LIKELY BE THIS EVENING INTO EARLY MORNING HOURS ON SATURDAY.

PREV DISCUSSION... /ISSUED 412 AM CDT FRI MAY 29 2015/

SHORT TERM...
LARGE SCALE SUBSIDENCE HAS TAKEN OVER THIS MORNING IN THE WAKE OF A
DEPARTING SHORT WAVE TO THE EAST. A NEW SHORT WAVE MOVING OVERHEAD
TONIGHT IN COMBINATION WITH A SURFACE COLD FRONT WILL BRING OUR LAST
HURRAH OF THUNDERSTORMS AND HEAVY RAIN FOR A WHILE. THIS INCOMING
SHORT WAVE AND FRONT WILL BE THE MAIN FORCING DRIVER FOR THE NEXT 24
HOURS. THERE ARE NUMEROUS SURFACE BOUNDARIES LINGERING AROUND THE
REGION FROM CONVECTION YESTERDAY AND EARLY THIS MORNING BUT AS
USUAL...NWP HAS DIFFICULTY RESOLVING SUCH SMALL SCALE FEATURES. THIS
MAKES THE AFTERNOON FORECAST INCREASINGLY DIFFICULT. WE WILL STILL
SEE MIXED LAYER INSTABILITY BETWEEN 1500 AND 2000 J/KG WITH A VERY
UNSTABLE AIR MASS. THIS INSTABILITY WILL CONTINUE THROUGH THE
OVERNIGHT HOURS. BACKED SURFACE WINDS WILL KEEP A BROAD AREA OF RICH
LOW LEVEL THETA-E AIR ALL THE WAY BACK IN EASTERN NEW MEXICO.
PRECIPITABLE WATER VALUES WILL CONTINUE TO BE IN EXCESS OF ONE INCH
WHICH IS STILL WELL ABOVE SEASONAL AVERAGES. DEEP LAYER SHEAR WILL
BE SUFFICIENT FOR ORGANIZED STORM STRUCTURES IF ANYTHING DOES
DEVELOP THIS AFTERNOON. DESPITE THE STRONG INSTABILITY AND
MOISTURE...THE LACK OF DEFINITIVE FORCING IN THE AFTERNOON DOES NOT
LEND MUCH CONFIDENCE TO THE POP FORECAST.

THE STRONGER AFOREMENTIONED FORCING INCREASES CONFIDENCE DURING THE
OVERNIGHT HOURS FOR MORE WIDESPREAD PRECIPITATION. HEAVY RAIN WILL
LIKELY BE THE PRIMARY THREAT THIS EVENING AND OVERNIGHT. VERY DEEP
WARM CLOUD DEPTHS IN EXCESS OF 3.0 KM WILL CONTINUE TO SUPPORT
WIDESPREAD HEAVY RAIN.

LONG TERM...
A COOL SURFACE HIGH PRESSURE RIDGE WILL BE SPREADING SOUTH BENEATH
HIGHLY MOIST AIRMASS SATURDAY MORNING...WITH AREAS OF RAIN OR
THUNDER FAVORING SOUTHERN AND EASTERN ZONES DIMINISHING BY
AFTERNOON. FLASH FLOOD WATCH CENTRAL AND EASTERN ZONES WILL
CONTINUE UNTIL 18Z SATURDAY. DEEP MID AND UPPER LEVEL DRYING WILL
FOLLOW LATE SATURDAY AND SUNDAY WHILE LOWER LEVELS WILL REMAIN
MOIST ENOUGH FOR SOME LINGERING CLOUD LAYERS.

THE BIG NEWS IN THE COMING WEEK WILL BE THE UPPER LEVEL HIGH
PRESSURE RIDGE NOW APPROACHING THE CALIFORNIA COAST...WORKING
ACROSS THE DESERT SOUTHWEST AND SOUTHERN ROCKIES THIS WEEKEND...
THEN PARKING ACROSS THE SOUTHERN HIGH PLAINS EARLY TO MIDDLE PART
OF THE NEXT WEEK. LOW LEVEL SOUTHERLY FLOW WILL RECOVER WITH
DECENT NEAR-SURFACE MOISTURE CONTINUING...BUT UPPER CONDITIONS
WILL BE MOSTLY ADVERSE AT LEAST TO ORGANIZED THUNDER CHANCES FOR
MUCH OF THE WEEK. AN EXCEPTION MAY BE LATE TUESDAY SHOULD
CONVECTION OVER HIGHER TERRAIN TO OUR WEST FIND A WAY TO SPREAD
TOWARDS THE TEXAS BORDER. THEN...PASSAGE OF THE RIDGE AXIS LATE IN
THE WEEK WILL ALLOW GRADUAL RETURN OF DEEP CYCLONIC CURVATURE AND
PERHAPS THUNDER CHANCES RETURNING THURSDAY NIGHT OR FRIDAY
WESTERN ZONES TIED TO HEIGHT FALLS ALOFT...IMPROVED CONVERGENCE
WITHIN THE SURFACE LOW PRESSURE TROUGH...AND RAMPING UP OF
PRECIPITABLE WATER VALUES. THE UPPER LEVEL RIDGE WILL ALLOW A
RECOVERY IN TEMPERATURES DURING THE WEEK...PERHAPS BACK TO NORMAL
BY WEDNESDAY OR THURSDAY ALTHOUGH SATURATED GROUND...VEGETATIVE
GROWTH...AND ELEVATED LOWER ATMOSPHERIC MOISTURE WILL TEND TO
LIMIT OVERALL HEATING ABILITY. RMCQUEEN

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM THIS EVENING THROUGH SATURDAY MORNING FOR
TXZ023>026-029>032-035>038-041>044.

&&

$$

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