Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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683 FXUS63 KAPX 221615 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 1215 PM EDT Sat Jun 22 2024 .KEY MESSAGES... - Flash Flood Watch in effect for today and tonight due to high confidence for torrential rainfall - Chances for severe storms today and tonight - Active pattern with periodic shower/storm chances throughout the upcoming week. Heavy rain possible. && .UPDATE... Issued at 1215 PM EDT Sat Jun 22 2024 Anomalous ridge to our south attm...with a couple pv maxima over WI. Anomalous moisture plume (pwats of 1.70" this morning at APX; 1.95 at GRB) overspreading the area along and north of the ridge and attendant E-W (ish) oriented boundary across the Upper Great Lakes. At the surface, this has begun to surge northward over NW Lower, with a NW-SE line of showers/storms that developed in the last couple hours and continues to shift northward amid good theta-e advection. Moderate to heavy rain continues to overspread NW Lower; rain is exceptionally efficient with deep warm cloud layer (at least 12,500ft) and some instability despite very moist profiles. Have gone ahead and continued the flash flood watch as things still seem to be on track for now. Expecting the warm front to stall out across northern Lower today...with more stratiform rain north of the boundary (most likely along and north of M-32)...which, while generally stratiform, could have pockets of more intense rain and embedded thunder this afternoon, with some concern for an increase in instability this afternoon in the warm sector despite potential for a dry slot to move in aloft. Additionally, tornadoes are still a threat today, given the unusually moist environment in the presence of some low- level directional shear. It won`t take much warming at all to boost surface-based instability dramatically as that warm front moves in...so will have to watch this closely going forward. Already having some concerns about NW Lower...where consistently better radar returns suggest the heavy rain threat could be enhanced if this keeps up. && .SHORT TERM /THROUGH TONIGHT/... Issued at 407 AM EDT Sat Jun 22 2024 .SHORT TERM/... Pattern Synopsis and Forecast: Current satellite and radar depict cloudy skies and light rain showers around northern MI this morning. Surface observations and emergency manager reports indicate areas of dense fog over Gladwin and Arenac counties this morning due to the very saturated and tropical-like environment. Light rain, clouds, and patchy fog will continue though the early morning hours as upper level winds continue to direct moisture over a surface low (center over ME this morning) and a warm front extending towards central MI. This feature will continue to slowly make its way northeastward towards the Great Lakes, with the center of the low possibly reaching northern MI Sunday. In the mean time, an anomalously moist environment will only get more wet. HREF guidance suggests PW values could reach 2" today. 00Z KAPX RAOB was 1.64" yesterday evening with a warm cloud layer almost reaching 13 kft. Very impressive warm rain environment, which has been producing around 0.5" to 1" with transient shower activity the past 3 days. This has all accumulated to around 1" - 4" 72hr QPE around the CWA, which has been keeping soils saturated. As the surface low gets closer (midday/afternoon today), southerly advection will strengthen and start to push that boundary northward. Slightly better forcing will give way to widespread moderate shower activity. CAMs depict 500 - 700 k/kg of SBCAPE trying to creep in from the south this afternoon. This could help develop embedded convection in the southern half of the CWA, however it will be heavily dependent on where the sun can creep in, or if storms forming over the central part of the state move into the southern CWA. If there is any clearing, expect storms forming near there to be very efficient rainfall producers. Low LCLs exist most of the short term period, and high lower level shear profiles will exist near the warm frontal boundary in the afternoon and evening hours. This yields low (but non-zero) chances for a few tornados near the areas of best shear this afternoon and evening. Winds aloft do strengthen in the afternoon hours as well, leading to chances for damaging wind gusts with storms that form. Flash flooding will also be a possible hazard as rain showers and storms train through much of the day, and chances for heavier convective rain exists on top of that. The surface low should reach northern lower tonight, with winds switching to the northwest Sunday morning and ending most of the rainfall chances for this round. Primary Forecast Concerns/Key Messages: Flash Flood Watch -- High confidence exists for torrential rainfall across northern lower today. Exact amounts and locations will be harder to pin down, as recent CAM guidance has trended slightly south, covering M-55 and even down into central MI now with heavy QPF swaths. It comes down to how far north the stationary/warm front boundary can reach. Afternoon convection should strengthen the surface low, leading to a decent southerly LLJ in the warm sector of the low. CAMs do point to the boundary setting up somewhere in the CWA, leading to those wide spread rain chances over northern lower. Thoughts on amounts tonight are - widespread additional 1-3 inches today and tonight with embedded convection possibly producing up to 5-6 inches locally. Severe Storm Chances -- Better chances will exist in the southern part of northern lower due to the proximity to the better instability. This is a very warm airmass that will nee some sort of additional heating near the surface or lower level warm air advection. Once we get that instability, the environment will be conducive for heavy down pours as well as damaging winds and, to a lesser extent, tornados. CAMs align on stronger winds aloft (~40- 50kts reaching down to 5-6kft) which could lead to damaging winds with storms that congeal. Lower level shear profiles near the boundary remain idea, but the uncertainty is with where that boundary can set up. If it is too far north, it will be too far away from the instabilty stronger storms will need. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 407 AM EDT Sat Jun 22 2024 Pattern Synopsis/Forecast: Sub-tropical ridge gradually retrogrades this week into a more climatologically favored location, eventually centering itself over the desert southwest. This places the Great Lakes in a very active northwest flow regime, with a train of northern stream shortwave energy poised to bring periodic shower/thunderstorm chances to northern Michigan throughout the week. This upper height configuration will also keep any significant heat away from the area, as the hottest temperatures are confined closer to the upper ridge to our west. Forecast Details: The surface low exits east of the area on Sunday morning with the heaviest rain departing. Despite transient low amplitude shortwave ridging behind the departing low, plenty of residual low level moisture lingering across the area with another upstream shortwave poised to drop into the area by late in the day. This will result in scattered showers/storms, especially during the afternoon and early evening hours. Thereafter, the forecast takes on an active tempo of precipitation chances every 2-3 days with an energetic northern stream dropping shortwaves into the Great Lakes. This results in shower and thunderstorm chances on Tuesday and again for the end of the week Friday/Saturday. Heavy rain once again will be a possibility as these waves tap deeper Gulf moisture, with PWAT`s surging to 150- 200% of normal across Michigan. No major heat on the horizon given this active northern stream pattern, with highs throughout the week generally in the 70s, with lows mainly in the 50s. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 555 AM EDT Sat Jun 22 2024 Warm/moist air will continue to push into the area as low pressure slides along a warm frontal boundary across northern Michigan. SHRA/TSRA will become more numerous by later this morning, continuing into tonight. Generally widespread MVFR and IFR cigs today with localized LIFR. The best chance for TSRA will be this afternoon into tonight, resulting in some TAFS having a lengthy period of TS. It may take until Sunday to get more widespread improvement in cigs, as drier air begins to push into the area. && .APX WATCHES/WARNINGS/ADVISORIES... MI...Flood Watch through Sunday morning for MIZ016>018-020>036-041- 042-099. MARINE...None. && $$ UPDATE...FEF SHORT TERM...ELD LONG TERM...JK AVIATION...JK