601 FXUS63 KIND 290138 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 938 PM EDT Sat Oct 28 2023 .Forecast Update... Issued at 938 PM EDT Sat Oct 28 2023 - Rain will continue to overspread central Indiana this Evening National radar mosaic was showing high coverage of rain across central Indiana this evening. The rain was mostly in the form of light returns with a few 40+ DBZ echoes mixed in. The rain was moving in to the Metro and also southeastern sections and should be over all or most of central Indiana within the next hour or so. The rain was associated with ongoing 305K Isentropic lift and disturbances in the southwest flow aloft. Potent northern Ontario jet (170+ knot jet max) places central Indiana in the right read quadrant which along with PWATs increasing to over 1.5 inches will allow for some enhanced rainfall at times. Look for most areas to see over a half an inch rainfall by morning and some areas could see an inch or more. There have been a couple of lightning strikes nearby, just south and north of central Indiana. So, would not completely rule out a stray lightning bolt or two the remainder of the evening, otherwise light to moderate rain with pockets of heavy rain will continue through the night with rain decreasing over the Wabash Valley toward daybreak. && .Short Term...(This evening through Sunday) Issued at 300 PM EDT Sat Oct 28 2023 - Rain Tonight and Sunday - Cool Surface analysis early this afternoon shows a cold front stretching from Western PA to East Central KY and then southwest to western TN. Large and cool high pressure was found over the western northern plains states, spilling into the upper midwest and Indiana in the wake of the cold front. Aloft water vapor shows the upper flow, consisting of a strong area of high pressure over the Gulf States and a broad low over Hudson Bay. This was resulting in warm southwest flow aloft across much of the United States. GOES16 shows extensive cloud cover across Central Indiana, with two features in play, the high clouds streaming across the southern parts of the forecast area and lower clouds invading from the north amid the weak cold air advection. Tonight - Active weather is expected tonight. The models suggest the quick upper flow aloft will become a driving force for precipitation. A 300mb jet streak near 130 knts is expected to push across WI and Michigan tonight, placing Indiana in a favorable position for lift on the right rear of the jet. Moisture streaming northward from this feature can be seen across OK/Arkansas, pushing northeast within the quick flow aloft. Forecast soundings across the area trend toward a saturated column overnight as this forcing and moisture arrive. PWATS trend toward 1.35 inches, which is quite high for this time of year. HRRR shows the showers to the southwest arriving in the area near 00Z and increasing in coverage as the night progresses. Thus confidence for rain is high tonight given the above. Best coverage should be found beneath the upper plume of moisture, across the southern parts of the forecast area. Thus will include highest pops there but only slightly lesser pops across the north. No matter where you are tonight in Central Indiana, confidence for rain is high. Given the expected clouds and rain, lows in the upper 40s to around 50 will be expected. Sunday - The upper pattern is little changed on Sunday. The strong pressure gradient aloft due to the deep low over the Hudson Bay and High pressure over the gulf states will remain in place. This allows for continued efficient transport of upper level moisture from the southwest along with continued favorable lift across Indiana in the right rear of the jet streak in place across the Great Lakes. After some morning subsidence within the upper levels, forecast soundings suggest deep saturation returns by mid to late afternoon with PWATs now near 1.15 inches. At that time, favorable forcing again appears in place aloft. Thus will continue to forecast rain on Sunday, with best chances during the afternoon. Again, given the expected clouds and rain, steady state temperatures around 50 will be expected. && .Long Term...(Sunday night through Saturday) Issued at 314 PM EDT Sat Oct 28 2023 * Additional Light/Moderate Rainfall Sunday Night Thru Early Monday * Near-Record Cold Monday-Wednesday Night...with Three Hard Freezes * Halloween Windy, Unseasonably Chilly, Few Flurries Possible The long term will begin with round two of this weekends rainfall... include several days of unseasonable chill and near-record cold mornings...and end with milder breezes bringing moderation to near normal through the late week. Sunday Night through early Monday... Sunday night will find the region amid the northwestern/back side of an elongated and somewhat broad moist ribbon extending from the southern Plains to the Northeast...between rather weak surface low pressure over the Mid-Atlantic and strong, broad high pressure plunging through the central CONUS. The region will be just far enough south/east to catch the ribbon's corresponding anafrontal overrunning rain, which will arrive from the southwest through the evening before departing rather quickly to the east through Monday's AM hours. Zones south of the I-70 corridor will likely see greatest rainfall yet again per longer duration under steadier rains. Potential for any locally heavier bands is less than with the short term's first round of rain as better deep moisture will have quietly departed to just southeast of the region. Nevertheless precipitable water values as high as 1.25 inches Sunday evening along the US-50 corridor may promote additional 15-hour rainfall through Monday morning up to 1.00 inch...while the solid majority of the CWA picks up another 0.25-0.75 inches of welcomed rainfall. While the aforementioned colder blast will begin entering Indiana early Monday, high confidence in precipitation ending as rain with readings near 40F. Late Monday through Saturday... Unseasonably cold and mainly dry conditions will then build into central Indiana on Monday as broad, amplified Canadian high pressure that will have plunged into the southern Plains then builds east. A dry column and westerly breezes that should prevent too much moisture from becoming trapped in the low levels should promote mostly clear skies...with diminishing winds Monday night under negative 5 Celsius H850 temps bringing a hard freeze to all zones. The most blustery conditions of next week's cold blast should accompany a potent short wave bringing a reinforcing shot of Canadian high pressure, arriving during PM hours Tuesday. Clouds, and most notably breezy to briefly windy conditions are expected, with west-northwesterly gusts to 20-35 mph impacting the region at prime trick-or-treating time...producing wind chills around 20F in the early evening. Flurries/snow shower potential also exists late Tuesday, but the moisture starved column, fast-paced nature of the supporting vort, and antecedent temperatures near/above 40F would not support any impacts. Any snow would be most likely north/east of Indianapolis where the combination of the passing wave's proximity and lake-enhanced flow would most likely combine. Cold overnights will continue Tuesday night and Wednesday night as the broad surface ridge oozes eastward while occupying most of the lower 48. Widespread mid-20s expected, and the CWA's notorious colder spots perhaps dropping to near 20F. Rather breezy conditions should continue during daylight hours...courtesy of the decent gradient aloft from the upper polar low's shift equatorward into Hudson Bay. However, this will also facilitate moderating southwesterly return flow through the late workweek...with reading returning to seasonable levels by the Friday-Saturday timeframe. The overall broad upper zonal trough pattern across much of the CONUS should continue mainly dry conditions through the late long- term, with guidance noting the next, rather weak short wave progged to bring a few light showers around the Saturday timeframe...while colder air remains retracted farther north into interior Canada. && .Aviation...(00Z TAF Issuance) Issued at 649 PM EDT Sat Oct 28 2023 Impacts: - Rain will reach KHUF around issuance time and the other TAF sites by 00z-02z - MVFR ceilings will deteriorate to IFR and worse at times in showers by around 05z Sunday - The rain will become more spotty toward 12z but more rain is expected by Sunday afternoon Discussion: Warm moist air streaming in from the southwest combined with impulses in the southwest flow aloft, will bring widespread rain and deteriorating ceilings tonight. After a brief break, more rain will return Sunday afternoon. Winds will be northeast and north less than 10 knots. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...MK Short Term...Puma Long Term...AGM Aviation...MK