108 FXUS63 KIND 191434 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 934 AM EST Thu Nov 19 2020 .UPDATE... The NEAR TERM Section has been updated below. && .SYNOPSIS... Issued at 157 AM EST Thu Nov 19 2020 High pressure in place over the middle Atlantic States in combination with low pressure in place over the northern plains will provide a dry and windy day to Central Indiana Today. A cold front is expected to push toward toward Indiana from the upper midwest on Friday. This will result in cloudy skies but dry weather on Friday. Chances for rain will return this weekend and the cold front stalls over Indiana as an upper level weather disturbance passes through the Ohio Valley. The cold front will exit the area on Sunday night brining cooler temperatures for early next week. && .NEAR TERM /Rest of Today/... Issued at 931 AM EST Thu Nov 19 2020 Issued a red flag warning for the afternoon and early evening hours today as models continue to show a high bias for expected dew points and low bias on high temperatures. After consulting with fire weather contacts across the state, it was determined that the risk for fires was worthy of the headline issuance. Made adjustments to hourly temperature and dew points which led to relative humidity values around 25%, but feel that likely areas will drop into at or below 20% for much of central Indiana, especially if dew points don't recover as models are showing. Either way, with winds frequently gusting in excess of 50-55 mph, the fire danger is serious today. Relevant portions of previous discussion follows... Models today continue to show a very quick zonal flow aloft in place today. High cloud amid this Pacific flow should pass across much of the forecast area today...particularly across the northern half. However the real story will be the winds. Forecast soundings showing 40+ knts winds just 2000ft above the surface with 60+ Knots winds in place at 850mb. Models showing a strong LLJ streak of nearly 70+ knot winds pushing across Central Indiana and Northern Ohio Today. Forecast soundings show a strong inversion in place near 900mb...thus the strongest of the wind should have difficultly mixing down. However...still within the lower levels BUFKIT Momentum Transfer suggest gusts to 40-45 knts this afternoon. Given this will extend the wind advisory across the entire forecast area today. As for temps with good mixing and little cloud cover and ongoing strong warm air advection will trend highs in the middle 60s today. && .SHORT TERM /Tonight through Saturday Night/... Issued at 157 AM EST Thu Nov 19 2020 This evening the strong and previously mentioned LLJ is expected to push east and as heating and mixing is lost winds are expected to diminish. However aloft the strong zonal flow looks to remain in place with little in the way of forcing passing aloft. Forecast soundings remain dry as warm air advection continues. Time heights show some lower moisture arriving overnight as the surface front sags closer to Indiana. Thus will trend toward a mostly clear evening followed by increasing clouds toward daybreak. Given the expected arrival of clouds will trend lows at or above the NBM. An elongated surface front is expected to be approaching Indiana on Friday and stalling through Saturday night. This will bring bring mainly just some stratocu clouds to Central Indiana as good lower level convergence will be place. Forecast soundings Friday through Friday night show saturated lower levels associated with warm air advection. However with no upper support...mainly just some cloud will be expected. Thus will trend toward just cloudy skies on Friday and Friday night...keeping temps close to the NBM. On Saturday...The lower levels remain very similar to Friday. The frontal boundary looks to remain in place across Central Indiana...allowing lower level moisture to linger. This time however the zonal upper flow brings a short wave across the Ohio Valley...providing some upper support. Forecast soundings respond by showing deeper saturation through the day within the column as pwats reach around 1 inch. Thus will continue with cloudy weather along with chances for rain on both Saturday and Saturday Night Given the favorable forcing and moisture will trend pops at or above the NBM...however this does not mean a big soaking event/washout. Rain amounts will likely be light and sporadic. Given the expected clouds and possible rain...will trend lows warmer and highs cooler the NBM. && .LONG TERM /Sunday-Wednesday/... Issued at 350 AM EST Thu Nov 19 2020 Some disagreement now exists regarding the extent of mid-level phasing that will attempt to develop a weaker-than-seasonable surface low on Sunday. The possibly more-zonal solution would yield a narrower/faster warm, moist conveyor over central Indiana...and weaker surface cyclogenesis along the stationary boundary stretched across the Ohio Valley. Therefore have followed the blend's slight downward trend in POPs, especially as the system departs to the east early Monday. However, rain is still likely late Sunday for the entire CWA. Have also maintained slight chances of wet snow mixing in late Sunday night, mainly north I-70, as marginally cold air arrives at the event's end... although given ample antecedent surface warmth, no accumulation is expected at this time. An overall zonal pattern will then prevail next week, providing a general seasonal chill through Wednesday. The region will catch the southern expanse of the next passing mass of Canadian high pressure, with light northwesterly flow providing a dry Monday- Monday night. Perhaps the stronger wave of the period will then cross the Mid-West Tuesday-Wednesday, although uncertain exists over the extent of southern energy phasing into the system...which would slow the troughs departure mid-week. Therefore maintained considerable cloudiness and chances of rain from late Tuesday through Wednesday. High temperatures next week will reach the mid 40's to mid 50's across the region, with lows in the 30's each night for most locations. && .AVIATION /Discussion for 19th/12z TAF issuance/... Issued at 700 AM EST Thu Nov 19 2020 IMPACTS: Very strong south-southwesterly flow throughout the period. LLWS threat through Friday 12z. Surface winds sustained 15-25 kts mid-morning through pre-dawn Friday, including gusts to 30-42 kts today during midday and afternoon hours. DISCUSSION: VFR conditions will prevail across central Indiana through Friday morning. Arrival of BKN deck pre-dawn Friday should stay above MVFR levels. Bigger story is the very strong low-level gradient between high pressure over the Carolinas and 998mb low crossing Ontario today. The resultant flow will include a 850mb LLJ of 60-70 kts over all TAF sites throughout the day...and surface winds increasing through the morning to 15-25 with gusts to 30-40 kts. Strongest winds will be this afternoon...with winds decreasing slightly this evening...before diminishing to around 10 knots from the southwest pre-dawn Friday. CONFIDENCE: High confidence in VFR conditions through pre-dawn Friday. High confidence in strong south-southwest surface winds sustained at 15 to 25 kts with gusts to 42 kts. High confidence in LLWS up to 60 kts at 020 through 10z Friday. && .IND WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 7 PM EST this evening for INZ021-028>031- 035>049-051>057-060>065-067>072. Wind Advisory until 5 PM EST this afternoon for INZ021-028>031- 035>049-051>057-060>065-067>072. && $$ SYNOPSIS...Puma NEAR TERM...Puma/White SHORT TERM...Puma LONG TERM....AGM AVIATION...AGM