807 FXUS63 KIND 311418 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 1118 AM EDT Fri Jul 31 2020 .UPDATE... The Aviation section has been updated below. && .SYNOPSIS... Issued at 139 AM EDT Fri Jul 31 2020 A pesky frontal boundary near the Ohio river along with a few passing areas of low pressure will result in cloudy and cooler days this weekend...along with chances for rain showers and isolated thunderstorms. Best chances for rain will be on Saturday and Saturday Night. Going into next week, a cooler than normal pattern will move in with small chances for rain during the first half of the week and dry conditions afterwards. && .NEAR TERM /Today/... Issued at 139 AM EDT Fri Jul 31 2020 Surface analysis early this morning shows an area of elongated low pressure in place across Kentucky...with a cool NW surface flow in place across Indiana. Aloft water vapor shows a deep trough in place over the Great Lakes stretching to an upper low over KS/MO. Radar mosaics show rain exiting southern Indiana...being more focused over KY...but still departing east. Skies were mostly cloudy across Central Indiana with dew points in the middle 60s. Today the models suggest the broad troughiness over Kentucky will sag farther south as an upper wave departs the area. This will allow for some marginally drier air to reside within the column over Central Indiana...leading to a few dry hours today. By late this afternoon...another round of upper forcing is depicted to be ejected from the upper low to the west. This should again provide forcing for scattered precip...particularly across the southern parts of the forecast area. Forecast soundings show a surge of lower level moisture arriving late in the day with pwats over 1.7 inches. Furthermore the GFS 305K Isentropic surface shows some lift arriving late this afternoon with very high specific humidities. Thus will start most of the day with dry pops but trend pops higher after 21z as forcing and moisture arrive. Will not trend far from the NBM on highs. && .SHORT TERM /Tonight through Sunday Night/... Issued at 139 AM EDT Fri Jul 31 2020 A mostly cloudy...cool and wet at times weekend is in store. The GFS and NAM suggest the broad trough in place over KY will begin to lift north as the upper low to the west begins to push toward Indiana for Saturday. An associated surface low is depicted to push into southern Indiana by Saturday. As these features arrive on Friday Night into Saturday...Time height sections show a gradual increase of saturation within the column...with best lift arriving by Saturday Night. Meanwhile the GFS forecast soundings show deep saturation arriving late Friday Night into Saturday...with pwats near 1.99 inches. Thus will trend pops at or above the NBM Tonight and Saturday as these features for rain remain in play. Given the expected clouds and rain...will trend lows warmer and highs cooler than the NBM. On Saturday night through Sunday the upper low is expected to pass across Indiana before exiting on Sunday Night. Best forcing with the approaching trough looks to pass on Saturday Night and Sunday as plenty of moisture is continued to be depicted across the area. Forecast soundings continue to show a deeply saturated column with pwats once again over 1.80 inches. Thus will continue with high pops on Saturday night and Sunday as these features pass. By Sunday night the upper low is suggested to depart. Forecast soundings begin to dry out as the upper trough axis exits to the east. Still cyclonic flow will remain in place across the area...but somewhat drier air is depicted within the column along with a lack of forcing. Meanwhile at the surface...weak high pressure is suggested to build across Indiana from the Tennessee Valley. Thus will try to trend toward a dry forecast at that time. && .LONG TERM /Monday through Friday/... Issued at 315 AM EDT Fri Jul 31 2020 The coming work week will be a somewhat unusual one, particularly for August. After chances for showers and storms early in the week owing to an upper level shortwave trough moving through the region, surface high pressure will move into the area and bring a prolonged dry but unseasonably mild stretch to central Indiana mid to late week. Temperatures and humidity look to be downright pleasant, particularly during the dry portions of the week. Blended initialization handled things well and required only minor adjustment. && .AVIATION /Discussion for the 31/15Z IND TAF Update/... Issued at 1118 AM EDT Fri Jul 31 2020 No changes needed to the TAF. Previous discussion follows... Issued at 720 AM EDT Fri Jul 31 2020 Primarily VFR through much of the period. MVFR ceilings possible at IND/HUF and likely at BMG late in the period. Cannot rule out IFR late in the period. Frontal zone remains stalled south of the area this morning, with ample moisture pooled along it. Low pressure will move along the boundary during the period and may produce showers and possibly a thunderstorm at BMG, and potentially also IND/HUF, as the period wears on. Uncertainty of timing and impacts precludes more than a vicinity mention at this time save for BMG where showers will be explicitly included late in the period. Winds throughout the period should be 10KT or less, generally out of the northeast. No significant obstructions to visibility are expected outside of showers or storms. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...Puma NEAR TERM...Puma SHORT TERM...Puma LONG TERM...Nield AVIATION...Nield/MK