Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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126 FXUS63 KABR 191146 AAA AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 646 AM CDT Fri Apr 19 2024 .KEY MESSAGES... - Windy again today, with gusts ranging from 35 to 45 mph across the forecast area. A few light snow showers (15-30%) possible as well, mainly over northern to northeastern SD into western central MN. Any accumulations, if any, will be minor. - Below normal temperatures through Saturday before warming back to near to above normal for early to mid week next week. - The next chance of rain (35-65%) will be Monday/Monday night. && .UPDATE... Issued at 636 AM CDT Fri Apr 19 2024 See below for an aviation forecast discussion for the 12Z TAFs. && .SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/... Issued at 255 AM CDT Fri Apr 19 2024 Short term models agree on a fairly stacked closed low intensifying as it pushes east and will be centered over western to central Ontario by 12Z this morning. This leaves the CWA on the southern side of this cyclone/troughing pattern with westerly flow (50-70kts at 500mb over the CWA) this morning and turning more northwesterly this evening on the backside of the low. At 850mb, gusty winds of 30- 40kts, out of the northwest, will also be over the area today and over the eastern CWA tonight through the overnight. An elongated high pressure system will start to swing down, with the high centered over southern Alberta/Saskatchewan by 00Z Sat. For Saturday, this high will be the dominant pressure system at the surface with a very positive tilted trough over the CWA aloft. With this setup, a steeper pressure gradient continues over the Northern Plains as 850mb temperature advection indicates -4 to -11C/12hrs this morning and rising to -2 to -5/12hrs this afternoon. Pressure rises won`t be anything spectacular, around 1- 2mb/6hrs, so the gusty winds will come from the CAA as several Rap soundings this morning indicate the classic "inverted v" look with mixing heights up to 850-700mb, tapping into these gustier winds. With daytime heating, soundings indicate sustained winds around 18- 20kts at the surface, which is around what the HREF is showing through the afternoon/early evening with Rap indicating gusts 25- 35kts across the CWA. NBM seems to be a little higher with sustained winds more 20-30kts with gusts up to 35-40kts. As this high gets closer and the low moves more east, winds will diminish west to east, but still could see wind gusts around 25-30kts over the Coteau through the overnight, as winds at 850mb stay stronger in this area. We are not expecting widespread wind advisory criteria gusts, however, some areas could be close so will need to keep a watch. Lastly, a few of the CAMs continues to spit out some northwest to southeast moving showers, in the form of snow, from late morning through this afternoon (15-30%). Soundings back this up, indicating saturation in the DGZ zone, however, omega really is not there as this is more a weakly forced environment. Lapse rates should be steep enough to help form these showers. This will mainly be over northern and northeastern SD into west central MN. Wet bulb temps will be below 0C during this time even as surface temps warm up above 0C which is why precip will stay as snow. Any accumulations will be minor. These showers will diminish towards the evening. With the cooler airmass overhead, temps will continue to be below average through the short term with highs ranging in the upper 30s to the mid 40s today and lows dipping into the 20s again tonight. Little bit of a rebound for Saturday with highs ranging in the upper 40s to the lower 50s. && .LONG TERM /SATURDAY EVENING THROUGH THURSDAY/... Issued at 255 AM CDT Fri Apr 19 2024 An active long term is possible, where it appears a couple of areas of low pressure could work over the region. When the period opens, high pressure at the surface and aloft is happening over the northern plains. Eventually, the high pressure influence is expected to give way to an area of low pressure bringing mid-level WAA-forced shower (35-65%) chances to the CWA heading into daytime hours on Monday. After spending some time in the (15 to 30 mph northwest wind) warm sector of this system Monday afternoon/evening, models are progging its cold front to sweep southward through the CWA by Tuesday morning. More high pressure at the surface and aloft for Tuesday/Wednesday (northwest flow aloft) until the upper ridge axis clears the region on Thursday. Timing differences are creeping during days 6 and 7, but "modest confidence" in steering flow features exists, at this point, with guidance depicting a large/broad western CONUS longwave trof establishing during the second half of next week, placing this CWA underneath southerly or southwesterly flow aloft by the end of the week. 15-35% PoPs start creeping into the forecast Wednesday night/Thursday, presumably as low level jet winds take shape and more moisture/instability is added to the column. Ensemble guidance PoPs continue to slowly rise right on through the end of the period, as the ensemble signal for precipitation potential increases. Looks like the "wind machine" will take a break Saturday night and Sunday, and Tuesday evening through Wednesday (the two instances when surface high pressure will be directly influencing the CWA). It also still appears that the warming trend being described for the early to middle portion of next week is in tact. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 636 AM CDT Fri Apr 19 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions are forecast to continue at all TAF sites today through Saturday. Winds will be out of the west/northwest, with sustained winds increasing to 15-25kts. Gusts could reach up to 30 to 35kts. Winds will be diminishing west to east late tonight through early Saturday morning. Isolated to widely scattered showers (some rain, but some snow) are expected to develop throughout the region this afternoon in daytime heating. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...MMM LONG TERM...Dorn AVIATION...Dorn