Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Nov 10 2022 12:59:17 ACUS01 KWNS 101259 SWODY1 SPC AC 101257 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0657 AM CST Thu Nov 10 2022 Valid 101300Z - 111200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WITH TORNADOES FROM TROPICAL STORM NICOLE -- FROM NORTHEASTERN FLORIDA TO SOUTHEASTERN NORTH CAROLINA... ....SUMMARY... A few tornadoes are expected during the day from northern Florida into eastern Georgia and South Carolina, and possibly overnight into southern North Carolina. Isolated damaging gusts are possible this afternoon across parts of the Upper Mississippi to Lower Missouri Valleys. ....Synopsis... A progressive mid/upper-level pattern is forecast through the period, featuring an intense synoptic-scale trough now along an axis extending from a low over southeastern MT to the Black Hills, central CO and southern AZ. By 00Z, the 500-mb low should reach eastern ND, with the trough maintaining positive tilt southwestward over the AZ/NM border region. The mid/upper low should cross the Boundary Waters region of the MN/ON border near the end of the period, with trough southwestward across the central High Plains and southern NM to northern Chihuahua. At 11Z, the associated low was drawn near RWF, with strong cold front southwestward across eastern NE, north-central/southwestern KS, and northeastern NM. A warm front was drawn from the low across western Upper MI to southern QC, and should shift northward across southeastern Canada through the period. The low is forecast to occlude today over central/northern MN, with a new triple-point low forming by 00Z over northern WI. The cold front should extend from there across eastern IA, southwestern MO, central OK, west-central TX, and southern NM. By 12Z, the surface low should reach ON near the north shore of Lake Huron, with cold front across northern Lower MI, the lowest parts of the Ohio Valley, the Arklatex area, and central/southwest TX. Meanwhile, T.S. Nicole is inland over central FL. See the next paragraph for more on this system's tornado threat, and NHC advisories for tropical watches/warnings and track/intensity forecasts. ....Southern Atlantic Coast... The threat for a few tornadoes has increased across portions of northeastern FL -- see SPC tornado watch 565 and related mesoscale discussions. The threat should expand northward through today and tonight to encompass more of the eastern parts of GA and the Carolinas. The central core region of T.S. Nicole is forecast by NHC to proceed northwestward across central FL this morning, before clipping the extreme northeastern Gulf or adjoining coastline near Cedar Key this evening, then turning north-northeast across GA late tonight. NHC also forecasts continual weakening of the max sustained winds. However, as usual for sheared TCs with a substantial onshore-flow fetch in the environmentally and climatologically favorable northeastern/eastern sector, low-level flow above the surface will take longer to weaken than surface winds -- especially inland. As such, large values of low-level shear and SRH will be maintained near the coast (e.g., 0-1-km SRH of 300-800 J/kg). Favorable moisture/buoyancy (70s F surface dewpoints beneath MLCAPE generally 500-1000 J/kg) should spread northward over parts of the GA/SC coastal plain today and into southeastern NC tonight, as low-level flow veers to a more direct onshore component. This process will advect higher theta-e boundary-layer air from longer trajectories over the Gulf Stream and northern Bahamas, leading to favorable inland destabilization where hodographs already will have expanded. In addition to the near-term tornado potential over northeastern FL, satellite imagery, lightning detections and distant radar views suggest a better-organized outer band, from north of the Bahamas to about 85 nm east of JAX. This suggests a more-favorable environment well offshore that should affect parts of the GA/SC coasts and vicinity later today. ....Upper Mississippi to Lower Missouri Valleys... Widely scattered thunderstorms may develop this afternoon within a frontal convective arc, from southeastern MN to central/north- central MO. Isolated to widely scattered thunderstorms also are possible in the nearby warm sector, though coverage is less certain due to more subtle lift. The most vigorous cells may produce strong to isolated severe gusts, and a brief tornado cannot be ruled out with any sustained supercell structures that may form. Strengthening deep-layer winds are expected over and just ahead of the cold front today, as the mid/upper trough approaches and height falls aloft continue. This will lead to immediately prefrontal effective-shear magnitudes in the 45-55-kt range, based on several models' forecast soundings. Thermodynamically, the scenario is more tenuous. Frontal lift will impinge on a weakly inhibited warm sector characterized by surface dewpoints near 60 F. Cloud cover will substantially limit surface heating and related diurnal boundary-layer lapse rates. Strongest large-scale ascent aloft and coldest air aloft will lag the front, keeping mid/upper-level lapse rates not much greater than moist adiabatic. As such, peak preconvective MLCAPE should reach only around 500-700 J/kg, and in a narrow corridor, with convection quickly outrunning that plume this evening. ...Edwards/Smith.. 11/10/2022 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .