Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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447 FXUS63 KIND 171328 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 928 AM EDT Wed Jul 17 2024 .KEY MESSAGES... - Isolated to scattered showers and non-severe t-storms this afternoon - Dry weather along with a break from the heat and humidity Thursday through this weekend - A return to warm and humid weather with thunderstorm chances next week. && .FORECAST UPDATE... Issued at 926 AM EDT Wed Jul 17 2024 The forecast is still on track for the day, with a few minor changes. Forecast high temperatures over far southern central Indiana have been increased slightly due to the expectation of a slightly deeper PBL and mixing heights this afternoon. Althrough isolated to scattered showers are still expected this afternoon, thunderstorm coverage has been decreased slightly. Morning ACARs soundings and WV imagery are hinting at a well elevated mixed layer (500-400mb) that will inhibit convective growth early this afternoon. A few, more robust, towers may be able to overcome this drier layer, but overall converage of cells producing lighting should be lower than previosly expected. This dry layer will also further reinforce the lack of severe storm threat for today. && .SHORT TERM (Today and tonight)... Issued at 300 AM EDT Wed Jul 17 2024 The short term will oversee central Indiana`s transition into much needed milder and less humid conditions, following a generally quiet cold frontal passage through midday today and the subsequent frontal zone`s crossing through tonight. Main weather concerns will be patchy fog early today amid dewpoints still lingering around 70F and mainly light winds. Underperforming or a complete lack of rainfall over the last 18+ hours should prevent organized areas of low visibility...yet less cloud cover than originally expected will maintain this concern through 12Z. Isolated to perhaps briefly scattered convection may accompany the boundary`s slow passing today as CAMs continue to indicate a few cells, with perhaps brief heavy downpours later today south/east of Indianapolis. At least moderate confidence in no further severe concerns with only a short late-afternoon window of weaker instability along/ south of the US-50 corridor, which upstream, better wind shear will not be able to catch. Any very localized flooding threat would be limited to southern zones through afternoon hours, with precipitable water values falling steadily as the front crosses today. Otherwise winds veering to north-northwesterly this afternoon will begin to usher in more pleasant conditions, with gusts up to 15-20 mph dropping dewpoints through the 60s over all counties by late day. This CAA flow should only allow near/slightly below normal afternoon highs, with 80-85F expected across the region. Slackening northerly winds under mostly clear skies tonight will promote lows in the 55-60F range. Lafayette`s forecast minimum of 57F would be the city`s first overnight below 61F in over two weeks. && .LONG TERM (Thursday through Tuesday)... Issued at 300 AM EDT Wed Jul 17 2024 The long term will usher in a much drier and relatively cooler airmass to central Indiana as surface high pressure moves into the Missouri Valley, a departing cold front moves south of the Ohio River and an upper trough pivots eastward bound across the Great Lakes. The center of the high will move across the lower Great Lakes Friday and stall out due to a blocking pattern courtesy of a expansive ridge over the western states. With 850 millibar temperatures as low as 9 to 11 degrees celsius Thursday, afternoon highs will only reach the 70s despite Hi-Res soundings supporting full sunshine. Temperatures will gradually modify but still stay a few degrees below normal through the weekend with afternoon highs anywhere from the upper 70s to middle 80s and lows in the upper 50s and lower 60s. The next chance of convection is expected to hold off until next week as the high moves off to the east. This will allow for a gradual return of southerly flow to potentially interact with an upstream broad trough as moisture and instability increase and combine with synoptic forcing. && .AVIATION (12Z TAF Issuance)... Issued at 657 AM EDT Wed Jul 17 2024 Impacts: - Potential brief IFR/MVFR CIGs from generally VFR-level deck this morning - VCSH through midday with isolated TSHRA possible south of I-70 - Winds veering to NNW by 20Z today...afternoon gusts to 13-16KT Discussion: Transition into northerly flow out of Canadian high pressure will continue during TAF period. Fair weather will prevail today between widely scattered -SHRA...although with confidence in both rain, and isolated VCTS, too low for any given location and time, have maintained VCSH mention in TAFs. Light winds early today will increase this morning while continuing to veer through northwesterly directions...to NNW flow this afternoon. Winds will be sustained at 6-12KT with gusts to 13-16KT. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Updike SHORT TERM...AGM LONG TERM...MK AVIATION...AGM