HEADLINES
– Wind gusts to 40 mph this afternoon and evening.
– Overall breezy and mild through the week, 50s by Thursday!
– Rainy Friday (maybe an inch) ending with rain (maybe snow mixed) Saturday morning.
TODAY’S MAP
NWS TECHNICAL DISCUSSION
High pressure will continue to gradually break down across the Central United States as a strong low pressure system moves southeastward across Canada. This low pressure system will gradually tighten pressure gradients across the Great Lakes region with 850mb wind speeds in excess of 40-50mph across north central Indiana. The biggest forecast challenge will be determining the depth of the boundary layer this afternoon with a wide spread on forecast temperatures this afternoon among the models. With the clearing yesterday, temperatures overachieved by 3-5 degrees compared to model guidance which also looks to be running cool for today with the expected sun and southwesterly surface flow. With the age of the residual snowpack across the area, there won`t be as much of a negative impact to rising temperatures which further gives higher confidence that temperatures may end up in the 90th-95th percentile of model guidance. If the higher end temperatures verify, the boundary layer may deepen to around 3-4kft vs the 2-3kft models currently are forecasting. This deeper mixing will tap into the core of the LLJ with wind in excess of 50 mph aloft and would lead to higher end wind gusts as high as 40 mph across central Indiana. Strongest winds are expected across the northern portion of the forecast area where the LLJ winds are maximized. Localized areas may see gusts of 45-50 mph, but coverage should be low enough not to warrant a Wind Advisory, especially considering those stronger winds are in a closer to the reasonable worst case scenario. Model wind gusts look much lower, but that is due to the underforecasted temperatures leading to a shallower mixing layer. Minimum RH values are expected to drop to around 30-35 percent this afternoon which could cause a concern for fires with the strong winds but with the wet ground and active snowpack, the threat will be limited. Tonight. Surface gusts will gradually taper down after sunset as the boundary layer begins to decouple, but with the very shallow LLJ, occasional gusts of 20-25 mph may persist through the early overnight. Another surge of upper level moisture will move in late this evening bringing a return to mostly cloudy skies through the early overnight, but expect that skies will then clear towards daybreak allowing for temperatures to drop back into the mid to upper 20s. There is a low but non-zero threat for a few light snow showers/flurries towards Kokomo late this evening, but confidence is too low for a mention in the forecast with the expected dry air near the surface and cloud deck closer to 6-8kft. && .LONG TERM (Tuesday through Sunday)... Issued at 312 AM EST Mon Jan 27 2025 A relatively quiet and significantly milder stretch of weather is on track for the coming week. A more progressive weather pattern sets up for much of the country as the polar jet retreats to the north, keeping the bulk of the arctic air in Canada. An subtropical jet remains strong, yet quasi- zonal and should stay south of the Ohio Valley, leaving much of the region in an area of upper level convergence and sinking air. Broad surface high pressure will generally be in control across the southeastern and central CONUS, while multiple systems traverse through the Great Lakes and Upper Midwest. This will allow for mostly dry conditions over the weekend into mid week next week, and for temperatures to moderate significantly, with highs and lows much closer to seasonal normals. At the surface, high pressure becomes centered over the Gulf states for the first half of the new week with warm air advection kicking out the colder airmass in place allowing for moderating temperatures. Indiana will be sandwiched in the middle of high pressure to the south and numerous low pressure systems moving across the northern CONUS, resulting in strong westerly flow as the low level pressure gradient tightens and a LLJ moves in overhead. Most of the energy and moisture with the northern stream systems will remain north of the region with high pressure keeping a much drier airmass in place. The main impacts from these passing lows to the north will be a reinforcing shot of cooler air in the Great Lakes creating a sharper SW-NE temperature gradient across the state and gusty winds Tuesday - Thursday. Low level mixing mixing and steeper lapse rates Tuesday will result in southwest winds 10-15 mph and gusts 20-25 mph, especially later in the day Tuesday as the LLJ strengthens. The low level airmass warms a bit more than the past few days with highs well into the 40s across Central Indiana. In fact, a few spots may reach 50 degrees in South Central Indiana with ample sunshine and good low level mixing. A similar pattern remains in place midweek as weak, moisture starved fronts pass by through the Great Lakes. Wednesday may be a few degrees cooler than Tuesday as brief cold air advection moves in behind a weak cold front and wind shift to the northwest. Still expecting highs in the 40s for most locations as deeper mixing occurs in the low levels. Once again, winds will be quite gusty upwards of 30 mph making for wind chills in the 30s all day. A significant warm up occurs Thursday as ridging builds with strong warm air advection. Expect widespread highs approaching the 50 degree mark. From Mon-Thu, bumped lows and highs toward the NBM75- 90th percentiles to account for guidance underdoing the warm air advection as the country comes out of the arctic weather pattern. The next opportunity for precipitation will come toward the end of the forecast period towards Friday Saturday, as a closed low, which will slowly drift through California and the Desert Southwest next week, begins to pull northeast toward the Great Lakes and be reabsorbed into a larger longwave trough shifting eastward into the central US. Guidance has sped up the arrival of the system, bringing rain into Indiana much of the day Friday, so have trended the forecast in that direction. Confidence is increasing that Indiana will be on the warmer side of this system with the majority of the precipitation falling as rain and highs potentially reaching the 50 degree mark again Friday and potentially again on Sunday as southerly winds return.
INDY SEVEN DAY FORECAST
Today: Sunny and breezy. Wind gusting to 35 mph! High 40.
Tonight: Mostly cloudy evening. Partly cloudy overnight. Low 30.
Tuesday: Sunny and breezy. High 43.
Tuesday Night: Clear. Low 34.
Wednesday: Mostly sunny. High 45.
Wednesday Night: Partly cloudy. Low 26.
Thursday: Partly sunny. High 50.
Thursday Night: Periods of rain, especially after midnight. Low 40.
Friday: Periods of rain. High 49.
Friday Night: Periods of rain. Low 35.
Saturday: Periods of rain, possibly mixed with snow in the morning. High 42.
Saturday Night: Mostly cloudy. Low 33.
Sunday: Mostly cloudy. High 50.

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