Area Forecast Discussion
Issued by NWS Goodland, KS
Issued by NWS Goodland, KS
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
628 FXUS63 KGLD 170957 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 357 AM MDT Tue Sep 17 2024 .KEY MESSAGES... - Windy today with southerly winds gusting 35 to 50 mph during the afternoon hours. - Severe weather is forecast for the area this afternoon and evening with wind gusts generally up to 75 mph, a few instances of large hail, and maybe a spinup tornado. && .SHORT TERM /THROUGH WEDNESDAY NIGHT/... Issued at 303 AM MDT Tue Sep 17 2024 Current observations show clearing skies as the last of the storm activity continues to shift further east into Central Kansas. Winds near the surface have lightened to around 10-15 mph from the south/southeast. For today, another warm and windy day is forecast ahead of an advancing upper low/trough. For the daytime hours, mostly sunny skies should allow temperatures to warm to around 90. The pressure gradient is forecast to tighten as the day goes on and allow winds to increase to 20-30 mph. However, the continued slight shift of the upper trough more to the north and with a faster motion is weakening the forecast flow in the low to mid levels. Guidance is now suggesting that the 850-700mb layer is going to have speeds more around 30-35 kts which would keep the gusts a tad bit lower. Have tuned the grids to match this with gusts now generally between 30 and 45 mph. There should still be an area or two that sees a gust near 50 in the west, as long as good mixing occurs. With the surface moisture advection from the southeast and continued moisture streaming in the mid levels from the southwest, dewpoints are forecast to generally be in the 50`s and 60`s which will prevent critical fire weather conditions. Still will probably be a bad day for burning though with most of the area having persistent dry conditions and the gusty winds. This afternoon and evening, the upper trough is forecast to begin more of a north/northeasterly track and push into the North/Central Rockies. This will begin to push the center of the lower surface pressure off the Front Range and pull the center north into Nebraska and the Dakotas. This should pull the better forcing and winds for storms to the north with it. However, the area should still see storms move through with storms firing up along the higher terrain in Eastern Colorado and with the surface field evolving to have southeasterly winds and southwesterly winds creating a surface convergence zone as the low moves east. With plenty of moisture available, the issue is not so much if the area will have storms (though gusting out could weaken storms before they get to the eastern half of the area), but if the storms will be severe and how strong. Locales closer to the low (northwestern parts of the area) are forecast to have winds push 60kts in the cloud layer where as locales further south are closer to 45-50 kts. Combining this with DCAPE around 1200 J/KG and downshear vectors around 45-50 kts, there is a good signal for storms to produce gusts generally to 65 mph. However, any storm in the greater flow (currently forecast as the counties near the Tri-State border) could see wind gusts push 75 mph if not 80 mph. This looks to be the bulk of our severe hazard this afternoon and evening as clusters and lines move through from west to east. However, given the moist environment and chance for additional convergence zones, isolated to scattered storms may form ahead of the main line. If these storms form, there will be a slightly increased risk for hail around one to two inches in diameter. the main inhibitor is that effective shear is generally forecast to be 30 kts or less so storms would have to be long lived and/or modify the environment to produce better shear and develop supercells. Within the expected mainline, the storm motion should be too fast and shear too low to support large hail development. Finally, it is worth mentioning that there is a low threat for a tornado or two in either the main line or discreet storms. The favored area looks to be along the Colorado border where discreet storms have a higher chance of forming. If winds near the surface become more southeasterly, the south to southwest lower level flow will have winds veer and create low level shear to allow for a spinup. QLCS tornadoes look to be unlikely as the 0-3km shear vector is forecast to be more parallel instead of perpendicular to the line of storms. Tonight, storms are forecast to move out and dissipate as the upper trough and lower pressure shift further north and east. This will begin to weaken our flow and allow winds to lower through the night. With lowering winds, clearing skies, and drier air moving in behind the system, lows could drop into the 40`s in the west while the east is more likely to stay in the 60`s. Tomorrow, another warm day is forecast as broad troughing continues and with no cooler air mass moving into the area. Highs should warm to near 90. Winds are forecast to be lower as the upper low continues to push off to the north and the next upper low/trough develops near the West Coast. This has winds forecast around 10-15 mph with maybe a few gusts to 25 mph. This could allow for briefly critical fire weather conditions in Eastern Colorado with drier air moving into the area and lowering RH into the teens. Otherwise, mostly sunny skies are forecast with the drier air forecast to be over most of the area. There is a low chance for a storm or two east of Highway 83 with a broad area of low pressure providing some convergence zones. If the dry air does not move most of the moisture out, a few afternoon/evening storms may fire off. Tomorrow night would have lows ranging from the 40`s in the west where it is drier, to 60`s in the east with the higher dewpoints. Skies should be clear with winds around 5 to 10 mph. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 353 AM MDT Tue Sep 17 2024 Overview: A modest upper level ridge will prevail over the central CONUS at the beginning of the long term period (Thu- Fri). Long range guidance suggests that a potent upper level wave.. presently situated offshore the coast of British Columbia.. will amplify and dig southward along the Pacific Coast today and Wed, stall invof central California on Thu, then gradually progress east across the Intermountain West (Fri-Fri night) and central Rockies/High Plains (Sat-Sun). Thursday: Clear skies and unimpeded insolation assoc/w the upper ridge over the region will foster dry conditions and above average temperatures, though.. a short period of breezy (15-20 mph) N winds and modest cold advection (assoc/w the passage of a weak surface to 850 mb /SFC-H85/ trough Thursday morning) could temper highs to some degree. Expect light/variable winds with temperatures ranging from ~82-92F during the afternoon, coolest in northeast CO. Friday: Upper level flow will back to the SW and strengthen late Fri and Fri night.. as the aforementioned upper wave progresses east across the Intermountain West. Forecast soundings suggest that deep vertical mixing and strengthening mid-level flow may yield breezy SW winds and exceptionally dry conditions over portions of the area late Fri afternoon.. particularly in eastern CO and adjacent KS border areas.. where a period of critical fire weather conditions is possible. Isolated high- based convection cannot be ruled out during the late afternoon, mainly south of I-70 where marginal high-based instability (~100-250 J/kg MLCAPE) may be present invof a modest low-level convergence zone /dryline. Very low confidence with regard to whether or not viable high-based convection will develop in the Goodland CWA. Sat-Sun: With a progressive upper wave progged to track east across the region this weekend.. expect cooler temperatures and well-above average chances for precipitation (in the form of scattered to widespread convection).. mainly Saturday afternoon through Sunday morning. Forecast specifics -- severe weather potential, in particular -- will highly depend upon the evolution and track of the upper wave/low. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1130 PM MDT Mon Sep 16 2024 For KGLD & KMCK... VFR conditions are forecast through the period. Main concerns are the strong surface winds through most of the day and thunderstorms during the late afternoon and evening hours. Winds are expected to increase through the day which will end the LLWS at KMCK. Starting as early as 21Z, but likely around 00-04Z, a line of storms is forecast to move through from west to east. These storms may be severe with mainly wind gusts to 50-60 kts and maybe some large hail. Once the storms pass, winds will begin to lower through the remainder of the night. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...KAK LONG TERM...Vincent AVIATION...KAK