Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Apr 26 2023 00:51:54 FOUS30 KWBC 260051 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 851 PM EDT Tue Apr 25 2023 Day 1 Valid 01Z Wed Apr 26 2023 - 12Z Wed Apr 26 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PARTS OF THE COLORADO FRONT RANGE INTO SOUTHERN KANSAS, MUCH OF OKLAHOMA, THE RED RIVER VALLEY, AND THE ARKANSAS RIVER VALLEY... ....Colorado Front Range to the Southern Plains and Red River/Arkansas River Valleys... The potential for excessive rainfall will linger from portions of the Colorado Front Range eastward and southward overnight as a mid- and upper-low wave makes its way eastward across the region along with low pressure at the surface becoming better overnight across parts of New Mexico. The latest HRRR runs have been showing most of the low-level CAPE diminishing in magnitude from the north and east across Colorado. Have trimmed much of northern Colorado out of the Marginal Risk area based on latest trends in satellite and radar. The better instability and better thermal contrast is farther south...thinking is that this will become the better focus for convection capable of producing heavy rainfall rates and potential for excessive rainfall. Still think that 1 to 1.5 inch per hour rates are possible over parts of the TX/OK panhandle later tonight into early Wednesday morning with the latest HREF showing the potential for 3 inch amounts from southern Oklahoma or the nearby Texas panhandle.=20 ....Southeast Florida... Convection over the Florida peninsula has been waning in response to loss of daytime heating...although some convection still lingers near the coast. Current thinking is that most...if not all...of the heavier rainfall rates and amounts during the remainder of the night will be remain offshore. Bann Day 2 Valid 12Z Wed Apr 26 2023 - 12Z Thu Apr 27 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE SOUTHERN PLAINS INTO THE ARKLATEX, ARKANSAS RIVER VALLEY, AND SOUTHERN OZARKS... ....Central-Southern Plains to the Ozarks, Arkansas River Valley, ArkLaTex, and Lower Mississippi Valley... The closed mid/upper level low is expected to push out of the Four Corners region early in the period, opening up as it approaches the Southern-Central Plains by early Thursday morning. With a stationary boundary draped across the region, southerly flow surging northward anomalous moisture will overrun this boundary and is expected to produce rounds of convection that track eastward across portions of southern Oklahoma and northern Texas early in the period before additional convection forms along the dryline across portions of Texas later in the day into the evening/overnight hours. The 12Z guidance including the HREF continues to show clustering of the greatest QPF signal for southern Oklahoma into northern Texas where the overlap of best forcing/low level convergence, moisture transport, and instability axis lies. HREF neighborhood probabilities reach 50-60% across parts of the Slight Risk area for 3-4" totals over the 24-hr period with some signal for 1-2" hourly totals at times, especially late in the afternoon into the evening hours. The Slight Risk was maintained with minimal adjustments based on the latest guidance and QPF trends. Hurley/Taylor Day 3 Valid 12Z Thu Apr 27 2023 - 12Z Fri Apr 28 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM PARTS OF THE LOWER-MID MISSISSIPPI VALLEY AND CENTRAL GULF COAST REGION THROUGH THE TENNESSEE AND LOWER OHIO VALLEYS, SOUTHERN APPALACHIANS, AND PARTS OF THE SOUTHEAST... The closed low ejecting out of the Colorado Rockies begins to open up as it tracks through the Southern-Central Plains and Mid-MS Valley Thursday-Thursday night, with multiple embedded vort lobes helping to provide large scale forcing for ascent across the outlook area. Deep layer southwesterly flow will bring up anomalous moisture, roughly around 1-1.5 standard deviations above normal. As the primary surface low lifts through the Ohio Valley, another area of low pressure is expected to form off the North Carolina coast. Overall, the convection that is expected to develop should be more on the progressive side, helping to limit the intense rain rates and overall duration. For this reason, the risk area remains capped at Marginal where broadly he system will become increasingly progressive with generally lower duration potential for heavy rainfall. Rainfall totals up to 1" (locally higher between 2-3" along the central Gulf Coast from New Orleans to FL Panhandle) will be possible. Hurley/Taylor Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7sa7ae-Dl2gMVcG_Rt-DzAESZMXdDQo1nq17bxI0EONy= jLZmrZvLZtX6G7V-g3FxR95hjulmecgxiXl7gvxw4kcbxBc$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7sa7ae-Dl2gMVcG_Rt-DzAESZMXdDQo1nq17bxI0EONy= jLZmrZvLZtX6G7V-g3FxR95hjulmecgxiXl7gvxw4M-rs_U$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7sa7ae-Dl2gMVcG_Rt-DzAESZMXdDQo1nq17bxI0EONy= jLZmrZvLZtX6G7V-g3FxR95hjulmecgxiXl7gvxw5K_DFNQ$=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) .