Area Forecast Discussion
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000 FXUS64 KLUB 290750 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 250 AM CDT Fri Mar 29 2024 ...New SHORT TERM, LONG TERM, FIRE WEATHER... .SHORT TERM...
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(Today and tonight) Issued at 250 AM CDT Fri Mar 29 2024 06Z upper air analysis reveals a broad, positively-tilted trough branching across the far northeastern Pacific Ocean and into the Intermountain West, with a weakening surface and mid-level cyclone rotating offshore of the Olympic Peninsula. Another well-defined cyclone was located due west of the 130th meridian and along the 40th parallel, and will continue to rotate southeastward towards northern California throughout the period as a 250 mb jet streak near 150 kt digs southward on the western flank of the surface and mid-level circulations. The broadly cyclonic flow extending eastward of these features contains numerous smaller-scale perturbations that were translating east-northeastward as the exit-regions of jet streaks analyzed by the 29/00Z upper air maps near 100 kt and 50 kt at 250 mb and 500 mb, respectively, nose into West Texas. Presence of these jet streaks have and will continue to advect a plume of mid- and high-level moisture originating from the northeastern Pacific Ocean, particularly along the southern-stream belt of deamplified flow. The cross-barrier component to the broadly cyclonic flow will also maintain renewed genesis of orographically-induced cirrus banding, with an expectation for thickening overcast to occur throughout the remainder of the morning and into the afternoon across the entire forecast area. At the surface, a diffuse trough was delineated generally along the 100th meridian as per recent METAR and West Texas Mesonet (WTM) data, where flow remains weakly confluent along its axis while remaining veered across the Caprock Escarpment. The nearest lee cyclone was analyzed in far southwestern Nebraska, though there appear to be indications of a weaker, secondary surface low forming across east-central New Mexico. LIDAR data out of LBB has also detected rapid intensification of the low-level jet (LLJ), with a speed near 50-55 mph at an altitude of around 700 ft AGL. After sunrise, the boundary-layer will begin to couple with dispersion of the intense flow associated with the LLJ occurring as it translates to the surface. This will result in breezy winds developing by the late morning hours while flow also veers southwestward behind the quasi-stationary surface trough as the lee cyclone to the north gradually rotates eastward. The surface trough should transition into a dryline today beneath the glancing influence of the amplifying trough to the west, and the net response from the geostrophic deformation aloft should cause the dryline to become much more sharp than yesterday (e.g., a dewpoint gradient of around 20 degrees over 30 miles across the Rolling Plains). Advection of the cirrus shield overhead will maintain some degree of subsidence in the mid-levels, which should be enough to prevent even warmer temperatures from coming to fruition. The dryline will retreat westward after sunset, while secondary cyclogenesis occurs later tonight across the TX PH, causing the dryline to arc nearly eastward across the extreme southeastern TX PH before bending southward in the southwestern South Plains. This will result in a temperature gradient of nearly 15 degrees heading into Saturday morning, ranging from the lower 40s to middle 50s from northwest-to-southeast, respectively, across the CWA beneath a clearing sky as high-level flow veers westward. Sincavage
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&& .LONG TERM...
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(Saturday through Thursday) Issued at 250 AM CDT Fri Mar 29 2024 The last weekend of March is shaping up mild and breezy despite an influx of high clouds in deep SW flow. This moisture is courtesy of a healthy subtropical jet preceding an upper low forecast to shift from SOCAL on Saturday to the Colorado Plateau by Monday. Meanwhile in the low levels, a dryline should be bisecting the CWA from SW-NE on Saturday morning all the while a backdoor cold front makes a run for our nern zones on the heels of a weak low departing into OK. These fronts can loiter much longer than models depict, so am a bit skeptical of NBM`s quick rebound to southerly winds and very mild temps in the Childress area by Saturday afternoon. Even with less wind than today, the dryline should easily mix off the Caprock by the afternoon, then retreat Saturday night before stronger SW winds from lee cyclogenesis in CO shove this east on Sunday. In contrast to the MAV`s much warmer highs this weekend, NBM`s temps seem legit given mostly cloudy skies on tap. Global models are in good agreement with strong height falls impacting the region on Monday as the upper low kicks across the Colorado Plateau. The remnants of the mid-level low over SOCAL are progged to drift east and over the Desert Southwest during this time and result in a broad, positively-tilted trough axis occupying the central and swrn CONUS by Tuesday morning. Upshot of this is that precip chances could start as early as Monday morning across our eastern zones as height falls and a Pacific cold front impinge on the retreating dryline. However, models are mixed on how fast the main upper low lifts out and consequently how much, if any, additional precip is on hand for the rest of our CWA. NBM`s PoPs through Tue morning look okay for now given the wealth of model spread and run-to-run variability, although its post-dryline winds were bumped up on Monday afternoon given the overall windier pattern. The next cold front dives south Monday night and could boost precip chances pending any residual moisture under the broad upper trough, though this may need to be culled in later forecasts if the trough trends more progressive and drier. Temps tumble to below normal territory for Tuesday ahead of milder values by Wednesday.
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&& .AVIATION... (06Z TAFS) Issued at 1217 AM CDT Fri Mar 29 2024 VFR prevails for the TAF period. LLWS will continue throughout the overnight hours and dissipate shortly after sunrise. LIDAR data out of LBB sampled a low-level jet near 40 kt at 700 ft AGL, and those shear magnitudes are expected to persist at KLBB and KPVW throughout the night. Shear magnitudes will be similar at KCDS based off of recent VWP data from the KFDR Doppler RADAR with heights at around 1 kft AGL. Winds will become breezy with gusts up to 30 kt possible tomorrow afternoon as LLWS dissipates and translates to the ground. Sincavage && .FIRE WEATHER...
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Issued at 250 AM CDT Fri Mar 29 2024 Critical fire weather conditions will be possible across areas within the current Red Flag Warning this afternoon. The combination of breezy, southwesterly winds; very warm temperatures, and minimum RH values in the lower teens should result in RFTIs around 3 to locally 4. However, ERC percentiles are not impressive and are hovering near the 50th percentile. This, combined with above normal fuel moisture and a thickening overcast, will preclude concerns for critical fire weather across the rest of the Caprock Escarpment. Winds will also shift slightly to the south-southwest ahead of the dryline in the Rolling Plains this afternoon. The Red Flag Warning will be maintained, and a Fire Danger Statement will be issued in place of the current Fire Weather Watch less the counties along the edge of the Caprock Escarpment. Winds will diminish rapidly after sunset tonight while becoming west, with RH recovery between 40-50 percent behind the dryline and 90 percent in the southeastern Rolling Plains. Fire weather concerns taper on Saturday until stronger southwest winds resume on Sunday, mainly near the TX/NM border. Critical fire potential could expand over much of the Caprock on Monday, although some rain chances by this time along with cooler temperatures could temper this threat at times.
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&& .LUB WATCHES/WARNINGS/ADVISORIES...
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Red Flag Warning from noon today to 8 PM CDT this evening for TXZ021-027-033-039.
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&& $$ SHORT TERM...09 LONG TERM....93 AVIATION...09

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