Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Nov 11 2022 00:57:41 FOUS30 KWBC 110057 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 756 PM EST Thu Nov 10 2022 Day 1 Valid 01Z Fri Nov 11 2022 - 12Z Fri Nov 11 2022 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHEAST... ....Northern Florida into the Southeast and Southern Appalachians... Continued to whittle down both the Slight and Marginal Risk areas in FL based on current observational trends (radar and satellite), now that the center of Nicole is crossing the FL Big Bend and drier air is wrapping into the eastern and southern side of the storm. Maintained the Slight Risk from the eastern FL Panhandle (northern portions) into southeast AL, southwest and central GA, and southern SC, where the low-level jet and moisture flux anomalies will be most robust (over 5 standard deviations above normal per the GEFS and SREF). Despite the ample moisture profile (PWs 2-2.1") and low-level transport, rainfall rates remain rather modest, owing to the forward speed of Nicole along with the meager deep-layer instability (MUCAPEs less than 500 J/kg inland from the Southeast coast). However, still can not rule out some enhanced amounts that leads to excessive rainfall in the inflow band or if there is a prolonged period of rainfall where Nicole pivots and takes on a northward track later.=20 Hurley Day 2 Valid 12Z Fri Nov 11 2022 - 12Z Sat Nov 12 2022 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR MUCH OF THE APPALACHIANS... 2030 UTC Excessive Rainfall Discussion... Very few changes were needed to the Marginal and Slight Risk areas tied with Nicole in the eastern U.S. as Nicole undergoes its extratropical transition and interacts with a broader scale trough. Inititally, higher rainfall amounts should be along the right-hand side of the system where moisture interacts with the southern end of the Blue Ridge and Allegheny range due to southeasterly flow pushing instability and moisture upslope...followed by increasing coverage of rainfall on the west side of the system in response to an approaching front. Except for some adjustments to account for shadowing by terrain and a subtle shift in the axis of highest QPF...few changes were needed. Bann Western Gulf coast... Precipitable water values are expected to rise to 1.75" while CIN erodes...which allows thunderstorms with heavy rainfall to break out across the region. MU CAPE should be 500-1000 J/kg upstream (to the southwest). here is a brief period Friday afternoon and evening where the low-level inflow/incoming boundary becomes progressive, which explains the spotty heavy rainfall seen on a few pieces of guidance. Hourly rain totals to 2" should be possible closest to the instability pool in southeast TX.=20 However, portions of LA and MS have areas which have received 200% of their seven day average rainfall this past week, increasing sensitivity. Issues should be isolated and mostly within urban areas. Roth/Wegman Day 3 Valid 12Z Sat Nov 12 2022 - 12Z Sun Nov 13 2022 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR NORTHERN NEW ENGLAND... 2030 UTC Excessive Rainfall Outlook Discussion... The forecast track and timing of Nicole continues to support a small Marginal Risk area...primarily in the first half of the outlook period. As a result...few changes were needed. Bann ....Previous Excessive Rainfall Outlook Discussion... Heavy rainfall within an area of low- to mid-level frontogenesis around the extratropical evolution of Nicole is expected during the morning and early afternoon hours before the system accelerates out of the area. Precipitable water values rise about 1.5", which is quite anomalous. Hourly rain totals to 1" are possible during this time frame. Spots of northeast NY, northwest VT, and westernmost ME have received 150-300% of their seven day rainfall, and moderate to heavy rain is expected the previous day. Thought it prudent to retain this Marginal Risk area, which was trimmed on its south side due to the accelerating model guidance. Roth Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8FFqgjfrZgtt_HtRvtUrg4olHbTzegQsMM9YfqLBMSrT= yOGNY03wrXhaRvppgyPvudED_igzOBX8jrMlkQKMY7mzLZk$=20=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8FFqgjfrZgtt_HtRvtUrg4olHbTzegQsMM9YfqLBMSrT= yOGNY03wrXhaRvppgyPvudED_igzOBX8jrMlkQKMo8AhFi8$=20=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8FFqgjfrZgtt_HtRvtUrg4olHbTzegQsMM9YfqLBMSrT= yOGNY03wrXhaRvppgyPvudED_igzOBX8jrMlkQKMz19ek08$=20=20 $$ =3D =3D =3D 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) .