Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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305 FXUS63 KIWX 080928 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 528 AM EDT Wed May 8 2024 .KEY MESSAGES... -Dry conditions expected today, with increasing chances for showers and thunderstorms after 8 pm EDT. Chances for showers and storms continue through most of the week, with highs in the 70s and 80s today dropping into the 50s and 60s Thursday into Saturday. We warm back into the upper 60s and low to mid 70s by Sunday. -Isolated strong to severe storms are possible this evening, mainly south and west of a line from LaPorte, Indiana to Lima, Ohio. The primary hazards with any strong to severe storms that develop would be heavy rain and localized flooding, damaging winds, and large hail. Confidence in severe weather occurring is low at this time. && .DISCUSSION... Issued at 528 AM EDT Wed May 8 2024 Quiet weather today with high pressure in control, just some morning fog to contend with-which seems to be shallow or at least not widespread. There could be a few dense spots, with Angola and Goshen and Elkhart bouncing between 4-6 miles and down to 1/4 mile. Opted to hold off on any SPS for now given the patchy nature and intermittent duration. Expect improvement after sunrise, with highs climbing into the 70s and low 80s under partly to mostly sunny skies. Clouds will be on the increase from south to north through the late afternoon as our next system approaches. The SPC Day 1 Outlook has roughly the southwest half of our CWA in a marginal risk for isolated strong to severe storms this evening (southwest of a line from LaPorte, IN to Lima, OH). Not too impressed with this set up for our area, and I suspect that severe weather will pass us just barely to the south this evening-so confidence is low. A cold front extends through central Lower Michigan into central IN (over our office, actually), and southwestward into IL/MO/OK, and it will continue eastward through the late morning (out of our area). A surface low developing along the front over MO will lift northeast through the afternoon into IL by 00z, lifting a warm front up to about our southern border (depends on the model). Have pops increasing from south to north starting at 8 pm EDT, which is better in line with the higher resolution guidance (hrrr/Rap). Expect the window between 8 pm and 2 am will be our best chance for severe weather, as this is when we have some surface based instability (300-700 J/kg, best early on), stronger forcing from the approaching mid level trough, a coupled upper level jet structure (west of the CWA, shifting east), and the bulk shear profiles are still decent (35-55 knots). The issue is that models are conflicted as to how far north the surface low gets, and then whether or not some discrete cells develop ahead of the main line early on (HRRR, RAP, NAM show this) then the convection along the cold front really takes off just to the south, which I suspect will limit the deeper moisture necessary for the higher continued pops (a lull). When the stronger jet coupling moves in, the surface low splits--which I suspect is where models are struggling--with the broader low remaining over IA/IL and the (I suspect) more mesoscale induced low moves along our southern border heading eastward. Some of the guidance has stronger mid-level lapse rates of around 7C/km, but per the latest HRRR/RAP/NAM they look to be around 5-6C/km, which is another strike against severe weather. The primary hazards with any strong to severe storms that develop would be heavy rain and localized flooding, damaging winds, and large hail. By 2 am, the instability wanes and we are limited as far as forcing goes (some stability behind the stronger line to the south), so the severe threat will wane significantly as well. As the LLJ kicks in and we get better moisture transport, expect showers to redevelop along the warm front either in the central or northern CWA (E-W orientation). Rain will continue through Thursday night, with isolated thunderstorms when we can get some instability. By Friday into the weekend, the entire Great Lakes is beneath an upper level trough, with a parade of rapidly alternating ridges/shortwaves that each bring chances for showers and maybe thunderstorms to our area on and off through the week. Today and Friday are the driest days, though this weekend into early next week we mainly have 20-40 percent chances (low confidence). Temperatures drop into the 50s and 60s until Sunday, when we see upper 60s and low 70s for highs. Temperatures warm into the low to mid 70s by early next week. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 233 AM EDT Wed May 8 2024 A cold front has moved east along with associated severe storms. Winds were still from the southwest behind the front. Patches of locally dense fog have been developing over northern Indiana bringing the potential that the fog may encroach upon the terminals. Conditional climatology yielded best chances for MVFR fog from 10Z to 14Z, so for now have went with a TEMPO MVFR fog during this period. The front will come back as a warm front, but the weather associated with this is likely to arrive after the end of the TAF period. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...MCD AVIATION...Skipper