Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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931 FXUS63 KDTX 150753 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 353 AM EDT Sat Jun 15 2024 .KEY MESSAGES... - Dry with seasonable temperatures today before abnormally warm conditions commence Sunday through much of next week. - Temperatures likely peak in the mid to upper 90s next week with maximum heat indices near/above 100F. - Low confidence thunderstorms could offset some of the warming, depending on coverage and timing. && .DISCUSSION... Atmospheric state is currently characterized by a longer wavelength ridge across the north-central tier of CONUS, flanked by a Pacific low descending along the coast of British Columbia and broad upper low over Hudson Bay that has begun to eject east. 15.00Z RAOBs reveal a region of +591 dam at H5 over the southern Plains which marks the infancy of a highly anomalous ridge that will build northeastward with time and bring dangerous heat to Southeast Michigan by Monday. As for conditions today, flow trajectories flip from cyclonically curved to anticyclonically augmented due to the approach of the aforementioned northern stream ridge. Stabilizing omega response noted with forecast soundings responding through warming/drying within the mid-levels, especially into the afternoon hours. Effectively clear skies offer broad insolation potential as the days creep toward the summer solstice. High temperatures will be tempered by the presence of veering low-level winds toward the ENE which promotes advective cooling, helped further by the influence of Lake Huron. Highs should largely hold in the upper 70s outside Metro Detroit (near 80 for the metro region). The southern ridge closes off and centers a bit further east Sunday, primarily over northeast GA and the western Carolinas while surface high pressure over the Great Lakes slides into The Northeast, strengthening to 1025 mb. This realigns sub-H9 winds southeasterly with warming conditions under the return-flow configuration. H8 temps jump significantly as the elevated portion of an approaching warm front lifts through from the southwest. Favorable model consensus of +18C by 18Z supports highs well into the 80s for most locations. A shortwave feature embedded within the mean flow will lift across northern Lower Michigan Sunday evening. The 15.00Z deterministic GFS has now fallen in-line with the corresponding ECMWF/CMC/NAM runs in keeping the precipitation just north of the CWA. Latest PoPs offer some minor refinements with a shift to only Slight Chance wording and a re-focus on Midland/Bay/Huron counties during the late evening timeframe. Overnight temperatures stay rather warm as lows hold near/above 70F. Record-setting heat remains a possibility Monday and at various points throughout next week as the mid-level portion of the ridge builds to 594 dam over North Carolina. Highs temperatures locally are still expected to peak in the upper 90s for most urbanized locations while confidence increases for similar readings for the outlying areas. Heat indices should break into the triple digits as max 0-3 km ThetaE values approach 360K with surface dewpoints in excess of 70F. The combination of +100F heat indices, overnight lows above 70F and the multi-day impact of highly anomalous prolonged late-spring heat warrants discussion of Excess Heat Watches/Warnings within the next update cycle. From an impacts perspective, the effects of this heat wave become more amplified for areas with higher population density. This is supported by the Experimental NWS HeatRisk tool where widespread Extreme Risk for Heat-Related Impacts (Level 4 of 4) could be reached. The ridge is expected to strengthen as it broadens northeastward along the Mid-Atlantic, peaking near 599 dam at H5 by Wednesday. EPS/CMCE/GEFS remain on-board with highs in the 90s through Thursday. Uncertainty festers wrt convective potential and subsequent modulation of thermodynamic profiles. MEX and GEFS datasets hint at slightly more "cooling" potential with various shortwave perturbations along the western periphery of the ridge. && .MARINE... High pressure remains in control this weekend, bringing gentle winds across Lake Huron. Conditions hold ahead of a warm front moving across the area Sunday evening. Chances for showers and storms accompany the front, mainly over northern Lake Huron. Southeasterly winds will veer southwesterly behind the front, increasing to 10-15 knots. Gentle to moderate winds alongside chances for unorganized showers will persist through the rest of the week. && .PREV DISCUSSION... Issued at 1153 PM EDT Fri Jun 14 2024 AVIATION... Clear sky and light NE wind are produced by tranquil high pressure extending southward from Ontario. These conditions continue through the morning with a slight uptick in wind speed toward noon as the boundary layer deepens. Clear sky is followed by a gradual cirrus increase while lake breeze enhanced easterly wind redevelops in the afternoon into Saturday evening. For DTW/D21 Convection...No thunderstorms are expected. DTW THRESHOLD PROBABILITIES... * None. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...KGK MARINE.......BC AVIATION.....BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.