Area Forecast Discussion
Issued by NWS Goodland, KS
Issued by NWS Goodland, KS
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231 FXUS63 KGLD 180345 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 945 PM MDT Wed Jul 17 2024 .KEY MESSAGES... - Thunderstorm chances continue through the end of the week with a risk for severe storms each day through Friday. - Temperatures remaining near normal through next week. - Locally heavy rainfall possible through Friday night. && .UPDATE... Issued at 750 PM MDT Wed Jul 17 2024 A large area of showers and thunderstorms over the northwest 1/3 of the area where precipitable water values run from 1.2-1.4 inches is forecast by the latest RAP/HRRR models to move to the east and southeast very slowly (0-6km wind speeds within the greatest confidence for rainfall under 10 mph) through perhaps 12 AM MDT (1 AM CDT). RAP model shows PWAT values increasing perhaps up to 1.7 inches generally north of Interstate 70. After midnight, some dissipation is forecast and could be a bit sooner. Increased and capped pops at 70% for now where confidence was highest in shower/thunderstorm activity to continue over the next several hours. Radar mosaic showing a slow decrease in storm intensity and despite the high precipitable water values and slow storm motions the overall threat for flash flooding looks to remain low and somewhat isolated. Severe threat looks to have diminished as well with some gusty winds and small hail the primary hazards with the locally excessive rainfall. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 1205 PM MDT Wed Jul 17 2024 17Z Water vapor imagery and RAP analysis indicated CWA under broad northwest flow with H5 ridge centered near the four corners region with trough centered over the northeast CONUS. PV analysis suggests at least 2 smaller disturbances moving over top of ridge to the west. At the surface broad and light easterly flow observed across area as surface ridge settles over the area. With dewpoints in the low 60s, already seeing CU fields develop, with storm initiation already occurring along weak convergence zone near KLIC. Primary short term concerns will focus on thunderstorm potential each afternoon and evening through Friday. As mentioned earlier, already seeing thunderstorm initiation on subtle convergent zone along Palmer Divide and expect this to continue on through the afternoon. While no major short wave trough is apparent upstream, inhibition looks rather weak allowing for several areas of thunderstorms to develop. The first will likely be along convergent zone/south of Interstate 70 in eastern Colorado, with storms moving east southeast through the afternoon hours. A second round of storms will likely initiate over the higher terrain and merge into more of an MCS in the evening hours. This will likely bring more widespread storms as it moves east into Kansas. Have doubts about how far east storms will make it as there is a rather sharp gradient in available instability and have opted to be a bit conservative on eastward progression. With instability around 1000 J/KG and fairly straight hodographs expect a few stronger storms early on, but think biggest threat will be organized cold pools/ damaging wind gusts. High precipitable water values, slow storm movement and high freezing levels support a heavy rain threat as well, but best potential does not seem to line up with where heavy rain has fallen recently. On Thursday, sfc ridge retreats to the east as trough strengthens over eastern Colorado. This will result in increasing southerly winds as well as increasing temperatures. While a similar upper level pattern will be in place during the afternoon, H7 temperatures will be several degrees C warmer than today resulting in stronger capping. Given the weak overall forcing, confidence in thunderstorm development not as high as today although threats will be similar to the last several days. Pattern continues on Friday although afternoon forcing looks to be stronger as weak cold front sweeps across the area. With more focused forcing along front, looks like Friday evening may be the best chance for rain across a large part of the area. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Issued at 1233 PM MDT Wed Jul 17 2024 Medium range models in general agreement with the overall large scale pattern through the middle of next week as flow aloft becomes more northerly and rather weak as H5 ridge remains firmly in place across southwest CONUS and weak cut of low develops over the Central Plains. While there is a bit of uncertainty with exact track of this low, somewhat surprised that it is pretty well accounted for in the GEFS mean showing at least broad consensus between ensemble members. Net result will be a cooler and cloudy weekend with showers possible through Monday. With current data, does not appear to be a great severe weather threat with weak shear and limited available instability. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 945 PM MDT Wed Jul 17 2024 KGLD...VFR conditions are expected through the period. A light and variable wind at taf issuance is forecast to continue through 12z. From 13z through the rest of the taf period, a southeast wind around 11kts is forecast, except in the 17z-02z timeframe where sustained speeds of 12-15kts with gusts up to 25kts are likely. Similar to the past several days, weather systems move through the area from the northwest. Given timing and coverage of storm issues, confidence is too low that the terminal would be impacted so no precipitation mention in this forecast. KMCK...VFR conditions are expected through the period. A light and variable wind at taf issuance is forecast to continue through 13z. From 14z through the rest of the taf period, southeast winds up to 11kts are expected except in the 22z-24z timeframe where speeds pick up into the 12-15kt range with gusts up to 25kts. Given timing and coverage of storm issues, confidence is too low that the terminal would be impacted so no precipitation mention in this forecast. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ UPDATE...99 SHORT TERM...JRM LONG TERM...JRM AVIATION...99