765
FXUS64 KLUB 211136
AFDLUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
536 AM CST SAT DEC 21 2024
..NEW AVIATION
KEY MESSAGES
- DRY AND MILD CONDITIONS ARE EXPECTED THROUGH WEDNESDAY.
- LOW CHANCES FOR QUICK-HITTING RAIN SHOWERS ON THURSDAY, WITH
WARM AND DRY CONDITIONS FORECAST HEADING INTO NEXT WEEKEND.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 300 AM CST SAT DEC 21 2024
ANOTHER COOL MORNING IS EXPECTED WITH CLEAR SKIES AND GENERALLY
LIGHT WINDS. LOWS WILL BOTTOM OUT NEAR 30 ACROSS MUCH OF THE REGION,
HOWEVER AS WAS THE CASE LAST NIGHT, MULESHOE AREA MAY DROP DOWN INTO
THE TEENS. WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH THE DAY
TODAY, HOWEVER SUBTLE HEIGHT RISES AHEAD OF AN UPPER RIDGE WILL
ALLOW FOR HIGH TEMPERATURES TO RISE TO A DEGREE OR TWO HIGHER THAN
YESTERDAY.
LONG TERM
(SUNDAY THROUGH FRIDAY)
ISSUED AT 300 AM CST SAT DEC 21 2024
AT THE BEGINNING OF THE PERIOD, THE MID/UPPER-LEVELS WILL FEATURE A
DAMPENING RIDGE ACROSS THE CENTRAL AND WESTERN U.S., WITH ITS
AMPLITUDE MODULATED BY A SHORTWAVE TROUGH EJECTING INTO THE NORTHERN
GREAT PLAINS. A MID- AND HIGH-LEVEL JET STREAK NEAR 70 KT AND 100
KT, RESPECTIVELY, WILL BE ROUNDING THE BASE OF THIS AMPLIFYING
SHORTWAVE TROUGH, RESULTING IN LEEWARD PRESSURE FALLS TO OCCUR
ACROSS THE GREAT PLAINS. MEANWHILE, A SECONDARY, MORE-SUBTLE
SHORTWAVE PERTURBATION IS FORECAST TO PROPAGATE OVER THE STATE OF
TEXAS ON SUNDAY, THOUGH THE DEEP-LAYER FLOW WILL BE SIGNIFICANTLY
WEAKER COMPARED TO THE NORTHERN GREAT PLAINS. AT THE SURFACE,
LEEWARD TROUGHING WILL EVOLVE WITH BREEZY, SOUTHWESTERLY WINDS
DEVELOPING BY THE LATE-MORNING HOURS ACROSS THE CWA. THE PASSAGE OF
THE SHORTWAVE PERTURBATION OVER TEXAS SHOULD ACT TO SHARPEN THE
SURFACE TROUGH FURTHER, AND WINDS WERE NUDGED UP A FEW KT FROM THE
NBM. GUSTS TO 25 MPH SHOULD BE COMMON AREA-WIDE ON SUNDAY AFTERNOON.
VERTICAL MIXING HEIGHTS SHOULD BE CAPPED NEAR OR BELOW 1-KM AGL AS A
WELL-DEFINED WARM NOSE REMAINS INTACT DUE TO THE 700 MB TROUGH
LAGGING BEHIND THE SMALL PV ANOMALY AT 300 MB, BUT TEMPERATURES WILL
STILL WARM INTO THE UPPER 60S AND LOWER 70S DESPITE THE SHALLOW
BOUNDARY-LAYER DEPTH. THE SECONDARY LEE CYCLONE, WHICH SHOULD FORM
NEAR THE RATON MESA, WILL ROTATE SOUTHWARD HEADING INTO THE EVENING
HOURS SUNDAY. FRONTOGENESIS ASSOCIATED WITH THIS SURFACE LOW IS
STILL EXPECTED TO BE WEAK, REDUCING THE MAGNITUDE OF CAA IN ITS WAKE
AS IT CROSSES THROUGH THE CWA ON MONDAY.
SIGNIFICANT AMPLIFICATION OF THE MID/UPPER-LEVEL FLOW WILL OCCUR
OVER THE WESTERN U.S. ON MONDAY AS AN INTENSE SHORTWAVE TROUGH DIGS
INTO THE PACIFIC NORTHWEST WHILE BECOMING NEGATIVELY-TILTED. A
THICKENING CIRRUS SHIELD ASSOCIATED WITH A WELL-DEFINED PV STREAMER
PROPAGATING DOWNSTREAM FROM THIS SHORTWAVE TROUGH WILL LIMIT FULL
INSOLATION FROM OCCURRING. THE PRESENCE OF THIS PV STREAMER AND
INTENSIFYING SHORTWAVE TROUGH NOSING TOWARDS THE PACIFIC COAST IS
EXPECTED TO RESULT IN A POSITIVE FEEDBACK OVER THE INTERMOUNTAIN
WEST, WHICH WILL AMPLIFY THE RESPECTIVE RIDGE WHILE ANOTHER
SHORTWAVE TROUGH FORMS OVER THE CENTRAL AND SOUTHERN GREAT PLAINS.
HIGH TEMPERATURES WERE LOWERED FOR MONDAY, WITH A 50-PERCENT
WEIGHTING APPLIED TO THE NBM 10TH PERCENTILE, PLACING THE FORECAST
HIGHS BETWEEN THE NBM AND THE MUCH COOLER MOS GUIDANCE. TEMPERATURES
WILL RANGE FROM THE MIDDLE 50S IN THE FAR SOUTHERN TX PH TO THE
UPPER 60S IN THE SOUTHERN ROLLING PLAINS. WHILE THERE IS SOME
INDICATION FOR LIGHT RAIN IN THE MESOSCALE GUIDANCE, THE SHALLOW
DEPTH OF THE LOW-LEVEL STRATUS DECK BENEATH A LARGE, DEEP SUBSIDENCE
LAYER SHOULD PRECLUDE THE STRATUS FROM BECOMING THICK ENOUGH TO
PRODUCE RAIN. A CONSIDERATION TO ADD IN FOG WAS ALSO MADE FOR THE
ROLLING PLAINS ON MONDAY MORNING, BUT UNCERTAINTY REMAINS TOO HIGH
TO WARRANT INCLUSION AT THIS TIME.
GLOBAL NWP GUIDANCE REMAINS IN AGREEMENT WITH A HIGH-FREQUENCY WAVE
TRAIN TO MOVE OVER THE CWA HEADING INTO THE MIDDLE OF NEXT WEEK,
WITH THE NEUTRALLY-TILTING SHORTWAVE TROUGH EJECTING INTO THE
ARKLATEX BY TUESDAY NIGHT. A REINFORCING SHOT OF CAA, ALBEIT WEAK,
WILL OCCUR ON TUESDAY FOLLOWING THE PASSAGE OF THE PRIMARY SYNOPTIC
COLD FRONT PREVIOUSLY LOCATED IN THE NORTHERN GREAT PLAINS. HIGH
TEMPERATURES WILL BE A FEW DEGREES COOLER ON TUESDAY AS A RESULT
WHILE REMAINING DRY. TO THE WEST, ANOTHER WELL-DEFINED PV ANOMALY
DOWNSTREAM OF A PARTICULARLY INTENSE EXTENSION OF THE PACIFIC JET
STREAM (I.E., APPROACHING 200 KT AT 300 MB) WILL PROPAGATE OVER THE
INTERMOUNTAIN WEST ON TUESDAY. THE NET RESULT OF THIS WILL BE AN A
POSTERIORI, SUCH THAT A SPLIT-FLOW PATTERN WILL DEVELOP OVER THE
WESTERN AND CENTRAL U.S., WITH THE SOUTHERN-STREAM BRANCH OF THE
ONCE NEGATIVELY-TILTED TROUGH BECOMING NEUTRALLY-TILTED AS IT
PIVOTS OVER THE FOUR CORNERS ON WEDNESDAY.
CYCLOGENESIS IS FORECAST TO OCCUR NEAR THE OK/TX PH REGION, WITH
RETURN FLOW BECOMING ESTABLISHED WHICH WILL BOOST TEMPERATURES INTO
THE MIDDLE 60S ON CHRISTMAS DAY. THERE REMAINS UNCERTAINTY WITH
WHETHER OR NOT A CLOSED LOW CAN FORM ALOFT, AND IF DOES, IT SHOULD
ALREADY BE VERTICALLY-STACKED, KEEPING ANY DEFORMATION BANDS TO THE
NORTH OF THE CWA. NWP GUIDANCE IS ALSO INDICATING A MUCH SHARPER
COMPONENT TO THE MERIDIONAL WAVEGUIDE, ESPECIALLY THE ENSEMBLE
SUITES COMPARED TO 24 HOURS AGO, AND THE LOW POPS HAVE BEEN
MAINTAINED FOR MOST OF THE CWA ON THURSDAY. HOWEVER, GIVEN THE
ESSENTIAL "FIRE HOSE" OF PV STREAMERS GENERATED BY THE EXIT-REGION
OF THE INTENSE EXTENSION OF THE PACIFIC JET STREAM, THE PROGRESSION
OF THIS SOUTHERN-STREAM TROUGH WILL BE FAST-MOVING AS IT BECOMES
NEGATIVELY-TILTING WHILE EJECTING INTO THE OZARK PLATEAU. THIS
SHOULD LIMIT THE SPATIOTEMPORAL EXTENT OF POPS ON THURSDAY, WITH THE
THINKING LEANING TOWARDS QUICK-HITTING RAIN SHOWERS AND LITTLE IN
THE WAY OF ACCUMULATIONS. THE FORECAST THEN REMAINS DRY AND WARM
HEADING INTO NEXT WEEKEND AS THE BULK OF THE PROGRESSIVE FLOW BEGINS
TO DISLODGE NORTH OF THE CWA.
SINCAVAGE
AVIATION
(12Z TAFS)
ISSUED AT 536 AM CST SAT DEC 21 2024
VFR AND LIGHT WINDS WILL CONTINUE.
LUB WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...19
LONG TERM....09
AVIATION...19
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