Why is it so complex to figure out? Because it is a cut-off low pressure system that is cut off from the jet stream or an attached cold front, it can meander in just about any direction it wants to. Yeah, it sounds like it has a mind of its own. Usually the upper level jet stream or, a warm front (mainly in summer) or, a cold front are the main drivers that push storms from west to east and south to north. That will eventually happen in this case but not before it wobbles around. As is wobbles around, it changes the temperature and precipitation on the east and west side of the wobble. Okay. I hope that's helpful.
Here's the current thinking from the NWS:
.SYNOPSIS... Issued at 219 AM EST Wed Nov 14 2018 High Pressure in place across Illinois will push across Indiana today bringing dry and cool weather today. Strong Low pressure is expected to build across the deep south tonight and push north across Kentucky and Tennessee. As the low approaches...wintry precipitation is expected to across Indiana on Thursday. This will result in some accumulating snow on Thursday along with the possibility of some freezing rain. The Low will quickly depart on Thursday night...ending the precipitation and bringing dry weather for Friday and Friday Night. Another weak cold front will sweep across Central Indiana on Saturday which could bring more light precipitation along followed by more cold weather for Sunday. && .NEAR TERM /Today/... Issued at 1041 AM EST Wed Nov 14 2018 Not much change to ongoing forecast. Did increase cloud cover across the southern half of the forecast area to account for a more invasive shield of mid to upper level clouds as the upper- level system over the Arklatex region heads our way during the day today. The northern edge of the mid to low deck associated with this approaching system is currently located over southeast Missouri into southern Illinois and southern Indiana. Expect the cloudiness to continue across much of central Indiana today...especially over the southern half of the area. Minor changes to temps but kept highs in the middle 30s going...as there was no appreciable change to the forecast that would warrant an increase or decrease there. && .SHORT TERM /Tonight through Friday Night/... Issued at 219 AM EST Wed Nov 14 2018 The GFS and Nam suggest a strong Cut-off Low lifting out of the plume of tropical moisture to the south and pushing toward and across Tennessee and Kentucky late tonight through Thursday. Strong indicators of plentiful moisture appear in place given the flow aloft. Excellent forcing appears in place as the low approaches and forecast soundings respond showing deep saturation through the day on Thursday. Top-down methods suggest some freezing rain will be possible on onset...particularly across the southern half of the forecast area as moisture arrives. Given the favorable expected path of the upper low...confidence is high for precip however confidence remains low on amounts and type. At a minimum...winter weather advisories will likely be needed and possibly more across the south where ice may mix in. Thus will stick close to the forecast builder blends pops tonight but trend toward 100 pops on Thursday. Furthermore will trend lows warmer and highs cooler than the blends given the expected clouds and precip. Best forcing exits the area quickly on Thursday night as the upper low departs the area to the northeast. Dry air arrives overnight as the Low reaches the middle Atlantic states. Although some lingering precip could still be present the first few hours after 00Z...the trend will be toward drying out. Forecast soundings show drying and subsidence within the column. Thus may keep a few pops across the east as the system departs but will overall trend toward a becoming partly cloudy and dry forecast. Given the possible snow on the ground and expected cold air advection will trend lows cooler than the blends. High pressure over the deep south on Friday and Friday night will nose north into the Ohio Valley. Forecast soundings and mid level guidance shows dry air and subsidence. Will trend toward a partly cloudy day and temps at or below the model blends. && .LONG TERM /Saturday through Tuesday/... Issued at 232 AM EST Wed Nov 14 2018 Ensembles are in good agreement in keeping broad upper troughing over the Midwest and East Coast during this period. There are still timing differences among the individual members as to a weak short wave trough that is expected to move through the area over the weekend. There continues to be a rather wide spread among the ensembles with respect to the timing of the precipitation threat with the weekend disturbance, anywhere from during the day Saturday to as late as Sunday night. Don`t see any real trends yet one way or another, so for now will go with chance PoPs for light mixed precipitation at times from Saturday through Sunday night. Precipitation amounts with this system still look to be on the light side.
That's wild!
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