Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 02 2023 20:34:57 FOUS30 KWBC 022034 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 433 PM EDT Sun Jul 2 2023 Day 1 Valid 16Z Sun Jul 2 2023 - 12Z Mon Jul 3 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE NORTHERN OHIO VALLEY TO NEW ENGLAND... ....Portions of the Ohio Valley Eastward to portions of the Pennsylvania/New York/New England.../ 16Z Update: The existing Slight Risk area was extended eastward to include southeastern Maine with a stronger QPF axis now in better agreement among the latest CAM guidance. There was also a westward extension to include the greater Chicago area and also including nearly all of Indiana and into portions of north-central Kentucky. This is in response to ongoing slow moving convection from northern Illinois into southern Michigan, and lower flash flood guidance over much of southern Indiana and surrounding areas with the expectation of new convection developing later today.=20 There was also a slight southward expansion of the Slight Risk to cover most of northern New Jersey where considerably lower flash flood guidance exists and an improved model signal for locally heavy rainfall there later today. An upper low initially over the Mid-Mississippi Valley will continue to move eastward over the Midwest and allow for slow-moving storms early. The Slight Risk area was maintained without too many changes given the support from the SREF/GEFS and the HREF neighborhood probabilities. The one change in pulling the western boundary of the Slight westward was largely done in response to late night/early morning radar imagery suggesting somewhat more training potential over northern Ohio as opposed to areas just to the south. PWs in the Northeast are forecast to be as high as +2 to +3 standard deviations above the climatological average, when combined with forcing along the frontal boundary will likely lead to some instances of flash flooding. Farther to the south, the Marginal risk area was again extended a bit farther south over northern AL and northern GA to account for slow-moving activity along and ahead of an approaching cold front. ....High Plains Adjacent to the Southern Rockies... The Marginal Risk remains in place today as the latest model guidance suite develops another round of mainly scattered coverage of late day convection in proximity to a lee side trough.=20 Rainfall amounts in most cases look to be modest, but there should be enough instability and low level moisture within a region of relatively steep mid level lapse rates to produce some localized downpours. The existing Marginal Risk area was extended southeastward to include portions of the Texas Hill Country where a stronger signal has developed in the HREF exceedance probabilities for flash flooding, and the same also holds true across portions of eastern Colorado and western Kansas where the Marginal Risk area was extended northward. The areas most prone to any flooding in New Mexico would be run off from recent burn scars. ....South Florida... Sea breeze initiated convection is already developing across coastal portions of South Florida late this morning, and this is forecast to gradually increase in coverage through the afternoon hours. Cell motions are expected to be quite slow owing to weak steering flow aloft, and new cell growth is expected to propagate along sea breeze boundaries and new outflow boundaries. HREF probabilities of flash flood guidance are elevated up to 40 percent across mainly interior portions of South Florida, with the greatest prospects in the 18Z-00Z time period. Therefore, a Marginal Risk has been introduced for much of South Florida through 12Z Monday. Bann/Hamrick Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_ZNek7mrbUgqaX-mLWmVTy_Vcqt6ApZ0-cu8nA72jQeN= onfoJd6Adh9x1B-1kHuYX-2LxPBuvK3N2-5hG4a57w_0WJc$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_ZNek7mrbUgqaX-mLWmVTy_Vcqt6ApZ0-cu8nA72jQeN= onfoJd6Adh9x1B-1kHuYX-2LxPBuvK3N2-5hG4a5WSz80G0$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_ZNek7mrbUgqaX-mLWmVTy_Vcqt6ApZ0-cu8nA72jQeN= onfoJd6Adh9x1B-1kHuYX-2LxPBuvK3N2-5hG4a5jDSD8Fc$=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) .