Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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404 FXUS63 KIND 111341 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 941 AM EDT Sat May 11 2024 .KEY MESSAGES... - Afternoon wind gusts of 30-35 mph today - Showers and storms return Monday into Monday night - Near normal temperatures for next week && .FORECAST UPDATE... Issued at 941 AM EDT Sat May 11 2024 Forecast is in good shape this morning. Rain has exited the area, as has most clouds. Adjusted sky cover as needed based on latest trends seen on satellite imagery. Additional cloud cover should develop today with cold advection (especially northeast). Mixing will lead to gusty winds and lower dewpoints this afternoon. Forecast has these in hand so no significant adjustments were made. Temperatures look good as well. && .SHORT TERM (Today and tonight)... Issued at 221 AM EDT Sat May 11 2024 Aurora viewing over the last few hours has been somewhat successful across central Indiana as clouds have remained scattered. However...starting to see an increase in mid level clouds ahead of a cold front currently located across the western Great Lakes with an area of showers along it. Rain is most numerous across lower parts of Lake Michigan with convection much more scattered south into central Illinois. 06Z temperatures were predominantly in the mid and upper 50s with light southwest winds. The frontal boundary is the primary focus in the immediate near term as it will sweep southeast across the forecast area during the predawn hours into the first part of the morning. Beyond that...much of today will be dry with windy conditions developing due to a combination of cold advection and a tight surface pressure gradient in the wake of the frontal passage. Clouds will overspread the northern half of the forecast area over the next few hours with a narrow band of showers following close behind. These showers will quickly drop southeast across the northeast half of the forecast area over the next 4-6 hours as the front moves across the region. Rainfall amounts will be light with most areas receiving no more than a tenth of an inch. Across the southwest half of the forecast area...it will largely remain dry with the wind shift from southwest to northwest signifying the frontal passage. Showers will be east of the forecast area by 12-13Z. The rest of the day will be similar to Friday with a mixture of sun and clouds as a healthy cu field develops for the afternoon in the cold advection and cyclonic flow present aloft. The primary difference from Friday will be the winds which will be higher for much of the day as the airmass becomes well mixed with dry adiabatic conditions up into the 650-700mb layer by mid to late afternoon. This should easily enable stronger winds to be drawn to the surface with gusts likely to peak at 30-35mph. Gusts will drop off quickly with sunset as high pressure expands across the Ohio Valley. Cu will diminish with the loss of heating and leave mainly clear skies overnight with light northerly flow. Temps...low level thermals are supportive of highs this afternoon ranging from the mid 60s northeast to the lower 70s southwest. With ideal radiational cooling conditions developing tonight...temperatures will fall into the mid and upper 40s over much of the forecast area. && .LONG TERM (Sunday through Friday)... Issued at 221 AM EDT Sat May 11 2024 A quasi-zonal pattern will dominate through much of the extended with a slow moving cutoff upper level low set to bring another round of wet and unsettled weather for the first half of next week. Another system will impact the Ohio Valley by Friday with another chance for rain. With the subtropical jet displaced well to our south throughout the extended...severe weather is not expected and the lack of appreciable instability will keep even the threat for thunderstorms limited through much of the extended. Sunday and Sunday Night Continued high pressure and the arrival of ridging aloft will make for a fantastic Sunday with abundant sunshine and temperatures recovering into the 70s to potentially lower 80s across the forecast area. CAMs beginning to pick up on a weak wave aloft drifting across northern portions of Indiana by the afternoon. With a deeply mixed airmass up to 700mb and little to no instability...not sure the wave will be able to generate much more than a light shower. That being said...closer analysis of the model soundings for late Sunday afternoon highlight steep lapse rates up through about 8kft which might be enough to get locally gusty winds to the surface with any isolated shower especially with dewpoint depressions on the order of 30-35 degrees. Will continue to monitor but most areas will remain dry all day Sunday. A cutoff upper level low will eject out of the Rockies on Sunday and move slowly east through the central Plains through early Monday. Mid and high clouds will begin to increase Sunday night ahead of this feature and the associated surface wave approaching from the west. Model soundings show residual dry air and subsidence will linger Sunday night and with moisture advection associated with the surface wave largely delayed until during the day Monday...dry conditions will persist Sunday night. Monday through Tuesday Night The upper low and associated surface wave will be over central Kansas Monday morning...and will track slowly east through the Missouri...mid Mississippi...Ohio and Tennessee Valleys through early Wednesday. Showers will gradually increase in coverage throughout the day Monday with the best chances for rain to come Monday night into Tuesday as the surface low drifts through the region. Recent model trends have initiated weakening of the upper low more rapidly as it arrives over the Ohio Valley with the attendant surface wave tracking further south than previously thought. This would result in the locally heavier rainfall rates potentially shifting closer to the Ohio River and points south and the sounding data supports this thinking as well with less moisture present through the depth of the column. Instability will remain weak throughout much of the period with abundant cloud cover limiting heating. CAPE values are subtly better on Tuesday in the immediate vicinity of the surface low but expect thunderstorms to be isolated to scattered at best. Despite the lower moisture levels showing up in the soundings...precip water values peak near 1.25 late Monday night into Tuesday. The setup supports the potential for non-uniform pockets of moderate to heavy rainfall...particularly on Tuesday and likely focused over southern portions of the forecast area with any slow moving convection. Expect 0.50 to 0.75 inches for much of the forecast area by Tuesday night with locally higher amounts confined to southern Indiana in closer proximity to the surface low track. High temperatures will rise into the 70s both Monday and Tuesday...held down slightly on Tuesday with increased rain and clouds over the region. Wednesday through Friday The upper low will weaken and eventually become absorbed by the mean flow aloft as it moves away from the region on Wednesday. After a cloudy start Wednesday as low level moisture lingers in the wake of the upper low...clouds will scatter as ridging aloft builds into the Ohio Valley. Temperatures will warm back up into the mid and upper 70s for Wednesday and Thursday with dry conditions. A surface low with an associated frontal boundary will move across the region late week with scattered showers and storms focused especially during the day Friday. && .AVIATION (12Z TAF Issuance)... Issued at 609 AM EDT Sat May 11 2024 Impacts: - Northwesterly wind gusts 23-27KT 15Z to 23Z Discussion: VFR conditions expected through the TAF period. Northwesterly winds will occasionally gust to around 25kts through much of the afternoon hours before weakening near sunset. Skies will clear through 15Z before diurnally driven clouds return mid afternoon. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...50 SHORT TERM...Ryan LONG TERM...Ryan AVIATION...White