Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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413 FXUS63 KTOP 280825 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 325 AM CDT Tue May 28 2024 .KEY MESSAGES... - Pleasant weather continues through midweek. - Off and on rain and storm chances enter the forecast again by Thursday into next week. && .DISCUSSION... Issued at 309 AM CDT Tue May 28 2024 Early this morning, an amplified upper trough was located across Quebec, Canada extending south-southwest across Great Lakes States into the mid MS River Valley. A second upper trough was digging southeast out of east central Canada into northern MN. Northwest flow aloft was noted across the Plains with a few embedded perturbations across western NE. An amplified upper trough was located across the Gulf of Alaska and extended southward across the northeast Pacific, off the Pacific Northwest coast. The 7Z surface map showed a cold front along the central Gulf of Mexico shoreline. The front then extended northwest as a warm front across southeast TX, northwest into north central TX, where it intersected a dryline west of ABI. South of the surface front dewpoints were in the lower to mid 70s across southern and central TX. Today through Wednesday: The H5 Trough across the Great Lakes and mid MS River Valley will shift east while the h5 trough digging southeast out of northern MN will phase with the main H5 trough across the eastern Great Lakes and OH River Valley. The weak perturbation combined with WAA/isentropic lift ahead of the richer moisture advecting into western OK and southwest KS will cause showers and perhaps a few thunderstorms to develop across west central KS this morning. These showers and storms will move southeast into south central KS. The northeast fringe of the shower and thunderstorms may clip the southwest counties. The RAP and NAM nest show a few showers developing farther east across the CWA but the HRRR, ARW and Fv3 show the greater chances for showers remaining southwest of the CWA through the early afternoon hours with only a few isolated showers or storms clipping the far southwest and southern counties. MUCAPE will only be 100-200 J/KG across the southwest counties, just enough instability for some weak thunderstorms. Mid clouds will increase through the mid morning hours and there may be some broken cloud cover at times late this morning and early this afternoon. The northeast and eastern counties will see more insolation. Highs this afternoon will reach the lower 80s. On Wednesday, the H5 trough over the eastern Pacific will move onshore across the Pacific northwest. A down stream H5 ridge will amplify across the northern and central Plains. The richer moisture return will shift a bit farther west across the TX Pnhdl and western KS. At the surface a ridge of high pressure will build southward out of IA into northern MO and far northeast KS. Slightly cooler and drier air will advect westward across the CWA. Highs will reach the upper 70s to lower 80s Wednesday afternoon. Wednesday night through Tuesday: A lee sfc trough will deepen as the H5 trough moves east across the central Rockies on Thursday. Richer moisture will advect northward across eastern KS late Wednesday night into Tuesday morning. Isolated to scattered elevated thunderstorms may develop in the early morning hours of Thursday. The H5 trough over the central Rockies will lift northeast across the northern Plains. Both the ECMWF and GFS forecast a southern stream H5 perturbation to move east across KS and OK Thursday night into Friday. This may be our best chance for showers and thunderstorms ( 60 percent or greater on Friday). Severe thunderstorm chances will be low, since the vertical wind shear will remain weaker given the H5 westerly winds will only be 15 to 20 KTS. So, I`m not expecting widespread severe thunderstorms. However, if the instability is higher there may be a few strong to marginally severe storms on Friday. Saturday, we may see a break in the rain chances as a low amplitude southern stream H5 ridge moves east across the southern Plains. Saturday night through Tuesday, the southern stream zonal flow will allow embedded perturbations to move across KS and the southern Plains. Precip chances will depend on the timing and amplification of these perturbations. The GFS brings a front through the area on Monday, which could bring in a slightly drier and cooler airmass on Tuesday and end our rain chances. The ECMWF is about 24 hours slower brining the front through the regions, so if the ECMWF verifies, rain and storm chances may extend into Tuesday. But both the ECMWF and GFS show a PNA pattern developing with a longer wave length trough across the eastern US and a broad amplified ridge axis across the west central US. This will keep the Plains in a dry northwest flow pattern from the middle of next week through the end of the week into the following weekend. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1242 AM CDT Tue May 28 2024 Expect VFR conditions through the next 24 hours. Light winds early this morning will become northwesterly by mid morning at less than 10 KTS. Winds may turn light and variable late this afternoon. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Gargan AVIATION...Gargan