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Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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576 FXUS63 KIND 191839 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 239 PM EDT Fri Jul 19 2024 .KEY MESSAGES... - Dry and pleasant into this weekend - Seasonable warmth and increasing humidity returns by late this weekend - Chances for rain/t-storms and increasing clouds next week may help keep temperatures slightly below normal && .SHORT TERM (This evening through Saturday)... Issued at 237 PM EDT Fri Jul 19 2024 Rest of This Afternoon... Scattered to broken coverage of cumulus will persist this afternoon, with some decrease expected late. Mild temperatures will continue with temperatures in the 70s to lower 80s. Tonight... Cumulus will dissipate this evening with loss of heating, but some cirrus will drift across the area. Overall though the night will be mostly clear. Winds will be light with high pressure still nearby. The combination of light winds and mostly clear skies could allow for some isolated fog, especially northwest. However, coverage is not expected to be high enough to include in the forecast at this time. These conditions will also allow temperatures to fall into the upper 50s to around 60 for lows. Saturday... Another quiet day with high pressure remaining in control is expected. Some high clouds plus some cumulus development will lead to partly cloudy skies for much of the area. With some gradual modification of the airmass occurring, highs will get into the lower 80s for much of the area. && .LONG TERM (Saturday night through Friday)... Issued at 237 PM EDT Fri Jul 19 2024 Upper Levels: Ensemble guidance is in agreement on the continuation of a deep upper level ridge over the western CONUS this weekend through most of next week. This will further reinforce general troughing over the Mississippi and Ohio Vallies, with some amplified troughing possible as the quasi-stationary Bermuda high builds westward towards the end of the extended forecast period. Low Levels and Surface: Currently, surface ridging is robust over the Great Lakes region, thanks to efficient CAA earlier this week. This high pressure will take time to erode, even with troughing aloft. However, eventually, upper level diffluence will prevail, with most of the Ohio Valley out of the influence of low level high pressure by early next week. Temperatures: Upper level troughing above strong low level high pressure will help continue the sub-seasonal temperatures for portions of this weekend, but temperatures will approach seasonal by Sunday as deep PBLs will aid in mixing and greater surface warming. Monday onward, surface high pressure will become weaker, but increased cloud cover and moisture will inhibit diurnal temperature gains, with highs remaining in the mid 80s. Greater southerly flow later in the week should give a subtle boost to temperatures, with highs by next weekend likely reaching the upper 80s. As mentioned, surface moisture will increase rapidly next week as the surface ridge breaks down. Current expectations are for surface dew points to push into the 70s once again by mid week, returning the summer-time feel to the air. Surface winds will remain very light through the extended period due to the lack of any significant disturbance. Precipitation: Upper level diffluence within a destabilizing atmosphere beginning on Monday will lead to an increases in diurnal thunderstorm chances throughout next week. Lapse rates are consistently greater than 6 C/km throughout he troposphere next week, further aiding in deep convective instability. The combination of deep instability and deep moisture will allow for very efficient rainfall rates within any thunderstorms. With storm motion expected to be very slow (Weak steering flow), pockets of 1-2" over short periods are possible. Outside of this, the flooding threat looks low outside of a low potential for mesoscale boundaries to help organize initiation. Without much shear, thunderstorms will have a difficult time organizing next week, limiting the overall severe threat. Still, given 3-4k CAPE and a high EL, updraft may be rather strong even in these brief windows of growth. This could lead to isolated hail and wind threats next week. Currently it is too far out to pinpoint any specifics on timing and location of severe potential && .AVIATION (18Z TAF Issuance)... Issued at 1250 PM EDT Fri Jul 19 2024 Impacts - Low probability of fog at KLAF near sunrise Discussion: Scattered to broken VFR cumulus will continue into early evening before dissipating. Additional cumulus will pop up on Saturday. With light winds and mostly clear skies, cannot rule out some fog at KLAF late tonight. However, confidence is not high enough to include at this time. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...50 LONG TERM...Updike AVIATION...50