Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX
Issued by NWS Dallas/Fort Worth, TX
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117 FXUS64 KFWD 271037 AFDFWD Area Forecast Discussion National Weather Service Fort Worth TX 537 AM CDT Mon May 27 2024 ...New Short Term, Aviation... .SHORT TERM... /NEW/ Update: Only changes from the discussion below was to keep the stationary surface front around between I-20 and the Red River as the main initiation point, albeit a very indiscreet. Any storm development will be quite "conditional" to say the least, as CAMs struggle with initiation on a run to run basis. So I kept PoPs capped at 20% until this evening, when a 20-30 kt LLJ can feed up into the Red River Region and assist in storm development. Otherwise, no changes to the discussion below about severity of storms in sheared and the explosively unstable airmass that will be in place over much of the region. 05/Marty Previous Discussion: /Memorial Day Into Tuesday/ ...More Severe Weather Returns Late Today Into This Evening... ...More Numerous Showers/Storms Tuesday With Locally Heavy Rainfall... After a much-needed quiet period yesterday and through much of Memorial Day, things unfortunately become quite unstable and volatile by this evening with unsettled weather continuing off and on Tuesday. The highest likelihood for isolated to scattered severe storms will be very late this afternoon and through midnight, with lesser chances overnight. Locally heavy rain and flooding gets added to the mix by later on Tuesday, as a very energized northwest flow aloft regime evolves across the area. A weak frontal boundary has stalled this evening along the I-20/30 corridors with tropical-like moisture and very light winds both ahead and behind this feature. I expect some fog to develop across especially eastern Central Texas where surface dew points are pushing around 80 degrees in spots. That`s unheard of this time of year across our region. It`s possible dense fog could develop across the far southeast counties enough for a brief advisory this morning, but will await development to occur. Our weak stalled front will mix readily north across possibly all but our northeast counties, as a strong shortwave induces pressure falls well west of the area. Peak heating will see temperatures soaring into the 90s with heat index values right to around 105 degrees across particularly eastern Central Texas where a Heat Advisory remains in effect through mid evening. In addition, the heat and rich moisture will help surface-based instability to soar up to 5000-6000 J/KG as additional mid level energy lifts northeast from Mexico. Combined with very steep lapse rates => than 8 Deg C/km, the atmosphere as noted beforehand becomes very volatile. This should help ignite isolated to scattered severe storms with all modes of severe weather possible, including tornadoes by this evening with discrete storms that can develop. The only thing missing is a surface focus, or coverage would be higher than the 20%-40% advertised. Still, most CAMs are showing the potential with the strong mid level impulse arriving late today. With this still being the end of the holiday weekend, those planning to be outdoors in this oppressive heat will need to keep a close eye on forecast updates and radar if possible. Though a few storms will linger near the stalled boundary across our northeast counties just past midnight, a downward trend in coverage and intensity of storms will occur as temperatures cool and subsidence briefly takes over overnight and Tuesday morning. Morning conditions will remain very humid and warm with lows in the 70s. After the reprieve Tuesday morning, the aforementioned evolving and energetic northwest flow regime sets up across the Southern Plains as the shortwave ridge to our immediate west dampens. Though more expansive cloud cover will hold high temperatures Tuesday to the mid-80s to the lower 90s, plenty of strong deep layer shear >40 kts, large-scale ascent, and steep lapse rates will again result in some severe weather with the added addition of flooding late in the day as localized heavy rainfall from more widespread convection evolves late in the day. Details are more murky on Tuesday regarding coverage and timing of impacts as models struggle with these scenarios of high moisture, instability, and energy aloft, so my advice is too stay abreast of the forecasts early this week. It looks like May is definitely going out like a lion versus a lamb. Wish I had better news. 05/Marty && .LONG TERM... /Issued 308 AM CDT Mon May 27 2024/ /Tuesday Evening and Beyond/ An active northwest flow pattern will set up over North and Central Texas by midweek as the region becomes sandwiched between a developing ridge over portions of the Desert Southwest/northern Mexico and troughing over the Great Lakes region. An initial shortwave perturbation looks to shift over a sharpening dryline late Tuesday afternoon/evening, initiating isolated to scattered convection over portions of West Texas and the Big Country. This activity will likely develop initially as supercells before growing upscale into a cluster of cells or possibly an MCS. With a northwesterly mean cloud-layer wind and a 25-35 southeasterly LLJ, this complex of thunderstorms will rapidly shift southeast toward our forecast area late Tuesday evening into the overnight. Where the initial convection occurs will play a large part in determining where this complex tracks Tuesday evening/night. However, there are several signals that our western Central Texas counties could witness the brunt of this complex`s impact. These convective systems tend to track along instability gradients, and most guidance right now places that SBCAPE gradient/weak, stalled frontal boundary generally along/south of the I-20 corridor Tuesday night. This track over western Central Texas and the Hill Country may also be reinforced by outflow from thunderstorms near the Red River Valley earlier in the day. Damaging wind gusts along the leading edge of this complex and isolated hail will be the primary hazards. Latest high-resolution guidance currently places an area along/southwest of a Breckenridge- Hillsboro line in the track of this potentially severe line of storms. The portion of this complex north of the instability gradient will likely be sub-severe with a lack of surface-based instability present. PWATs approaching 1.9-2.1" and warm cloud depths greater than 15,000ft will make these thunderstorms very efficient rainfall producers and several locations beneath these storms could pick up a quick 2-3" of rain. Continue to monitor the forecast over the next couple of days as we further refine location and timing details. This active pattern will continue through the rest of the work week with daily chances for thunderstorms over portions of North and Central Texas through at least Saturday. Coverage Wednesday may be more isolated, but the next chance for more widespread rainfall looks to arrive late Thursday into Friday as another compact shortwave progresses overhead through the northwesterly flow aloft and the aforementioned stalled frontal boundary lifts north toward the Red River enveloping most of the region in moderate surface-based instability. Severe weather will be possible at times. Additionally, multiple rounds of heavy rainfall will increase the flooding threat, especially over already saturated areas. Otherwise, temperatures will be slightly tempered by clouds and precipitation with widespread afternoon highs in the 80s and low 90s and overnight lows in the mid-60s to low 70s. Langfeld && .AVIATION... /NEW/ Update: /12Z TAFs/ Weak surface boundary still fluctuating within the DFW Metro area with spotty IFR/MVFR BR, particularly DAL/GKY. Only other change to the discussion below is to delay VCTS until after 00z Tuesday, as CAMs really struggle with the boundary and any discrete TS development in/near the D10. Confidence remains low, but bears watching throughout the day. 05/Marty Previous Discussion: /06Z TAFs/ A weak FROPA made it to about I-20(I-30 out E), but has since lost any upper support with AFW/FTW/DFW seeing light NE around 5-7 kts with light S or VRB winds at DAL/GKY 5 kts or less. Moisture to the south of this boundary is very tropical-like and high and with only light S or calm winds, I can`t rule out spotty 5-6sm BR near GKY and possible DAL/FTW by 12z, but the better bet for MVFR/IFR and possibly LIFR conditions will be at ACT between 10z-14z. Once the old boundary and ESE/SE winds pick up to between 10-15 kts, then all sites will see VFR with SCT Cu and high clouds. With the old surface front out of the area, scattered TSRA are expected over the DFW D10 area by 00z Tuesday and have an added a VCTS until almost 03z per latest CAMs. The only driver will be mid level energy arriving at peak heating. However, with a very unstable airmass, look for TS+ and GS/GR to occur with TSRA. 05/Marty && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 95 72 87 71 83 / 20 30 50 60 50 Waco 93 72 89 71 83 / 20 20 40 60 50 Paris 92 67 85 66 79 / 10 20 40 40 50 Denton 93 69 84 68 81 / 20 30 50 60 50 McKinney 93 69 83 68 81 / 20 30 50 50 50 Dallas 95 73 88 71 84 / 20 30 50 60 50 Terrell 91 70 86 68 82 / 20 30 50 50 40 Corsicana 91 71 90 71 85 / 20 20 40 50 50 Temple 92 72 89 71 84 / 20 20 40 50 50 Mineral Wells 95 70 88 68 82 / 10 20 50 70 50 && .FWD WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM CDT this evening for TXZ135-145>148- 158>162-174-175. && $$