Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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904 FXUS63 KIND 061318 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 918 AM EDT Sun Oct 6 2024 .KEY MESSAGES... - Elevated fire weather risk this afternoon, especially along and north of the I-70 corridor - Dry and warm weather continues today. - Seasonable temperatures to start next week, warming trend back to upper 70s mid to late next week && .FORECAST UPDATE... Issued at 918 AM EDT Sun Oct 6 2024 Surface analysis this morning shows a cold front stretching from Michigan to eastern IL and then southwest to southern MO. Strong high pressure was found over the northern plains. This cold front was moisture starved. GOES16 shows clear skies across Indiana and only shows a few high clouds over Michigan ahead of the front. However, due to strong low pressure over Ontario, a moderate pressure gradient remained in place across Central Indiana. This afternoon the front is expected to sweep across Central Indiana, eventually allowing the winds to become northwesterly. However in the meantime Indiana will see plentiful sunshine and good mixing with southwest flow in the warm sector. Given this, expect temperatures to overperform somewhat, reaching the middle 80s. Due to the moderate pressure gradient, gusty winds will be expected this afternoon. Gusts around 25 mph will be possible. Skies will remain sunny as forecast soundings remain dry with convective temperatures that are unreachable. && .SHORT TERM (Today and tonight)... Issued at 255 AM EDT Sun Oct 6 2024 Today... An upper system will move through the Great Lakes today. At the surface, a cold front will move through central Indiana this morning into early afternoon. The cold front will be moisture starved, with moisture confined to the Great Lakes area and the upper system. Thus, only expect some patchy mid and high clouds as the front moves through today. Winds will increase as the pressure gradient tightens with the frontal passage, and mixing will bring down some gusts from stronger winds aloft. Winds will gust into the 20 to 25 mph range, with perhaps a few higher gusts. The higher wind gusts look to be across the northern forecast area where stronger winds aloft will exist. Temperatures will warm quickly today with sunshine. Better cold advection won`t arrive until later in the day. Given the above and a warmer start than previous days, expect highs in the lower to middle 80s across much of the area. Some upper 70s are possible in the north where cold advection will be strongest. Drier air will work in quickly behind the front, and the combination of the drier air and warm temperatures will lead to low relative humidity. See the Fire Weather section for additional information. Tonight... Winds will diminish quickly with loss of heating/mixing. High pressure will build into the area, but center of the high will remain west of central Indiana. Skies will be clear for much of the night, but some scattered lower clouds may move into the far north late tonight in the cold advection regime. The combination of dry air, lighter winds, mostly clear skies, and cold advection will lead to low temperatures in the lower to middle 40s. Areas sheltered from any wind will have the potential to see the coldest readings. && .LONG TERM (Monday through Saturday)... Issued at 255 AM EDT Sun Oct 6 2024 A prolonged warm and dry spell will persist through next week as strong high pressure and ridging dominates the region. Despite sunny skies and warm temperatures, there will be enhanced fire danger concerns each afternoon, as well as potentially deteriorating drought conditions once again. High pressure dives southeast out of Canada this weekend becoming centered over the state by Tuesday. Cold air advection and northerly flow ahead of the system will "cool" temperatures down from summer- time levels to near normal for this time of year. Normal highs and lows are currently right around 70 and 50, though steadily declining through the month - by mid month we lose another 4-6 degrees on average. Monday and Tuesday will likely be the only days in the long term that are "near normal" as a warming trend begins as ridging strengthens and high pressure shifts eastward late in the week. Both long term and deterministic guidance are in good agreement with this warming trend with highs reaching the upper 70s again by Friday and into next week. Dry conditions will likely lead to enhanced diurnal temperature ranges, with lows each night dropping to the 40s to low 50s. Watching Monday night into Tuesday morning for the coolest lows in the long term period as optimal conditions for radiational cooling set up with high pressure directly overhead. Watching the Wabash River Valley and wind sheltered areas away from urban areas for the potential for mid to upper 30s. Will continue the trend of adjust forecast dewpoints and RH downward toward the NBM10-25th percentile during the afternoons many days this week, as despite relatively light winds, it will require only modest mixing in a very dry column to produce potentially substantial dewpoint drops in the afternoons. This is an area where NBM is known to struggle, often significantly. The aforementioned light winds will mitigate fire concern somewhat, at least with respect to reaching red flag conditions, but continually drying fuels and afternoon RH values potentially nearing critical levels will present at least some concern. Longer term guidance does suggest some potential for precipitation near or just beyond the end of the forecast period with another quick moving upper low and cold frontal passage late next weekend into early the following week, but long term outlooks remain fairly strongly warm and dry, and prevailing westerlies look to remain displaced well poleward for most of the next couple of weeks at least. CPC 6-10 and 8-14 day outlooks are strongly indicative of below normal precipitation and nearly as strongly indicative of above normal temperatures, and this is well-supported by long term guidance, including the CFS. && .AVIATION (12Z TAF Issuance)... Issued at 630 AM EDT Sun Oct 6 2024 Impacts: - Wind gusts around 20kt today, with a wind shift to northwest Discussion: VFR conditions are expected throughout the period. A cold front will move through the sites late morning into mid afternoon. Some mid cloud may accompany the front, and a wind shift to the northwest will occur with it. Can`t rule out some brief low level wind shear at the start of the period with some stronger winds aloft. Winds will gust to around 20kt during the day today both ahead and behind the front. && .FIRE WEATHER... Issued at 255 AM EDT Sun Oct 6 2024 An elevated risk of grass and field fires will occur this afternoon across central Indiana, especially across areas along and north of the I-70 corridor. Over a week has passed since significant rainfall, and observations indicate that 10 hour fuels continue to dip to near critical levels for a few hours during the afternoon. The drier air will be moving in coincident with the warmest temperatures will lead to minimum humidity in the 20 to 30 percent range over much of the area, with the lowest values in the northwest where drier air will arrive first. Some of the hi-res models indicate the potential for sub 20 percent humidity, and the DESI viewer is showing around a 40 percent chance of this happening in the Lafayette to Kokomo areas. The above, combined with wind gusts over 20 mph (and potentially 25 mph north) and the lower afternoon fuels, will lead to the elevated risk for grass and field fires. Will issue a Special Weather Statement to highlight the threat. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Puma SHORT TERM...50 LONG TERM...CM AVIATION...50 FIRE WEATHER...50