Area Forecast Discussion
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Issued by NWS
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491 FXUS64 KLUB 061724 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 1224 PM CDT Sat Jul 6 2024 ...New AVIATION... .SHORT TERM... (Today and tonight) Issued at 314 AM CDT Sat Jul 6 2024 07Z upper air analysis depicts a shortwave trough pivoting over the central and eastern portions of the U.S., with several smaller-scale perturbations and vorticity maxima translating through the belt of amplifying flow in the mid-levels as per recent water-vapor imagery. Farther west, a subtropical, mid/upper-level ridge continues to amplify over the western U.S. as a baroclinic low over the northern Pacific Ocean becomes vertically-stacked. The superposition of these features has maintained northwesterly flow in the mid-levels while the right entrance-region to the 250 mb jet remains over the southern Great Plains. An ill-defined shortwave perturbation translating over the Sangre de Cristo Mountains has also generated a band of elevated convection that was propagating southeastward towards the CWA, though it is not particularly well-organized based on trends in recent KAMA WSR-88D imagery with only a few cores remaining intact. PoPs throughout the remainder of the overnight hours through 15Z have been left intact as the multi-cellular line of storms continues to propagate southeastward towards the NM/TX state line; however, spatial coverage of storms should be limited owing to the magnitude of subsidence aloft as observed by the 06/00Z RAOB from WFO AMA. At the surface, an anticyclone was centered in JTN with the cold front far removed from the CWA and near the I-10 corridor based on recent METAR and West Texas Mesonet (WTM) data. GOES-East Nighttime Microphysics imagery detects a few areas of low stratus beginning to develop across the southern South and Rolling Plains, though anvil debris associated with thunderstorms in the Big Bend has somewhat obscured this view. The expectation is for low stratus to steadily form over the next few hours across portions of the CWA as the southeasterly fetch and related adiabatic expansion causes the lower boundary-layer to reach its saturation point. The surface high will also rotate eastward throughout the remainder of the morning and into the afternoon, with surface winds becoming southerly area-wide with clouds eroding by early-to-mid-afternoon. Temperatures will warm into the upper 80s across the CWA as well, and subsidence from veered/westerly flow at 700 mb that becomes northwesterly above will cap vertical mixing heights and prevent any further adiabatic warming today. PoPs were removed for this afternoon due to the lack of surface and low-level convergence, and as the diurnally-driven cu field is entrained by dry air as parcels ascend from the LFC. The southerly breeze will increase throughout the overnight hours as lee cyclogenesis continues across southeastern Colorado beneath the amplifying shortwave trough and as the exit-region of an upstream 250 mb jet streak noses into the western High Plains, resulting in a warmer morning on Sunday compared to this morning. Sincavage && .LONG TERM... (Sunday through Friday) Issued at 314 AM CDT Sat Jul 6 2024 The mid/upper-level, subtropical ridge over the western U.S. is forecast to deamplify on Sunday morning as the baroclinic low over the northern Pacific Ocean begins to become neutrally-tilted and start its transition into an open trough. The net result of this synoptic-scale evolution upstream of the CWA will cause the broadly cyclonic troughing to deepen and attain a positive-tilt, and will be further aided by the coupling of a 250 mb jet streak extending southward out of Saskatchewan. Cold frontogenesis will occur at the surface and low-levels, with the frontal movement expected to be convectively-reinforced by a Mesoscale Convective System (MCS) along the front as it moves southward across the central Great Plains. Ahead of the cold front, hot temperatures near 100 degrees are expected to occur as the eastern periphery of the Pacific ridging eclipses the CWA, with 850 mb temperatures approaching 30 deg C. The airmass will become uncapped by this point with boundary-layer mixing heights ascending to near or above 700 mb which will galvanize an Inverted-V profile as southerly flow strengthens to around 20 mph by peak heating. PoPs were increased from the blended initialization across the Rolling Plains given the expectation for potentially widespread thunderstorms to form along the cold front as it surges southward across the southern Great Plains. How far west convection unzips remains unclear and the blended PoPs were maintained across the Caprock, and it is possible that a dry passage occurs across the Caprock. Blowing dust may accompany this front especially due to the possibility of its movement being reinforced by thunderstorm outflow. Anomalously high precipitable water (PWAT) content, in addition to a belt of high theta-e air advecting poleward towards the southward-surging front beneath the right entrance-region to the 250 mb jet streak, will lead to the potential for heavy rainfall and flash flooding, particularly across the Rolling Plains, on Sunday night. PWAT content in excess of 1.50" is forecast across the Rolling Plains during this time, and rain rates between 1-2"/hr will be possible; however, the progressive movement of the front and an unfavorable alignment of the Corfidi vectors for back-building will temper a more-significant flash flood potential. Post-frontal, elevated showers and thunderstorms may persist into Monday morning and afternoon across portions of the CWA as an intense shortwave trough digs into the central Great Plains and the entrance-region to the 250 mb jet streak further amplifies. The favorable ascent profile throughout the column (i.e., easterly, upslope, low-level flow; and divergent mid- and high-level flow in vicinity of the right entrance-region of the jet streak to the north of Tropical Cyclone Beryl) yields enough confidence to maintain PoPs through Monday night. Much cooler temperatures are also forecast on Monday, with temperatures in the upper 70s to lower 80s expected as dense overcast restricts diabatic heating. The mid/upper-level shortwave trough is forecast to translate northeastward by Tuesday, and the resultant NVA on the backside of the trough combined with the subsidence to the west of the remnants of TC Beryl leads to a dry forecast for most of the day with the exception of areas nearest the TX/NM state line. Subtropical ridging is once again forecast to amplify over the Desert Southwest on Tuesday, and diurnally-driven convection across eastern NM generated by weak perturbations translating along the eastern periphery of this ridge may propagate southeastward into the western South Plains late Tuesday evening before the potential wanes after the boundary-layer decouples. Renewed chances for storms will return Wednesday and Thursday afternoon across the Caprock as northwesterly flow aloft remains intact before drying out towards the end of the week as the subtropical ridge shifts eastward followed by a warming trend. Sincavage && .AVIATION... (18Z TAFS) Issued at 1215 PM CDT Sat Jul 6 2024 VFR expected next 24 hours. There exist a low risk of thunderstorm activity, primarily N/NW of KPVW late this afternoon into the evening hours. Thermal turbulence will be quite prevalent (and noticable) during the afternoon until the cumulus clouds start to disappear around sunset. Increasing storm chances, particularly at KCDS, are indicated just after the valid time of this TAF cycle. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...09 LONG TERM....09 AVIATION...26