Subj : HVYRAIN: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Feb 02 2023 06:28:17 FOUS30 KWBC 020628 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 127 AM EST Thu Feb 02 2023 Day 1 Valid 01Z Thu Feb 02 2023 - 12Z Thu Feb 02 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY INTO CENTRAL GEORGIA... Antecedent saturated soil conditions due to consistent parade of storms over the last few weeks have been highlighting the concern for the potential for showers and thunderstorms to present an elevated risk for excessive rainfall and flash flooding has highlighted within prior day's Excessive Rainfall Outlook discussions. Soil conditions (per NASA SPoRT-LIS products) are not much improved with soil moisture values running above normal particularly across much of LA into MS as well as increased streamflows noted in USGS gauges, warranting a one category bump in risk. However, the prior Slight Risk was predicated on stronger cells and available instability and moisture flux convergence to drive stronger cells and higher rainfall totals across this region.=20=20=20=20 00z model cycles along with satellite and observational trends has seen the shortwave trof over the Southwest continue to shear into the confluence zone across Texas into the Tennessee Valley with reduced amplification. This, in turn, has further reduced the strength of the return Western Gulf low level jet. While there is a narrow window just crossing the 02.12z time barrier into early morning for enhanced isentropic ascent and moisture convergence to develop some broken area of showers and weak thunderstorms, the reduced upslope flow has tempered moisture flux convergence and advection of unstable air northward as in prior guidance cycles.=20 While some guidance suggests thunderstorms capable of 1"/hr, most have trended away with 00z HREF probability of 1"/3hr falling below 40% throughout the time period with max values across S LA into SW MS. Given this is concurrent with the most saturated ground conditions, there was some weak potential for maintaining a small Slight Risk across this area. However, in coordination with local forecast offices, the limited coverage and forward progression of cells that would develop would be scattered enough to be better suited for a Marginal Risk. Additionally, the Marginal Risk from prior cycles was trimmed southward and narrowed across MS/AL into central GA. There is increased convergence in model guidance toward the axis of prolonged light to moderate over-running precipitation throughout the day with areal averages of 1-1.5" possible. Consideration for saturated ground conditions across NW LA to broaden the Marginal ever so slightly relative to downstream locations across E GA into SC, where the Marginal Risk was removed given better soil conditions and lower rainfall rates. Gallina 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!75LpJpXS65MfZ9jto11_acDTk8ETi0NBYAXogL8R69MI= AM-YmDCMWwrEtd2Ik5GXWnNR4nffYw5SDsDng1ieQ8MF0uk$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!75LpJpXS65MfZ9jto11_acDTk8ETi0NBYAXogL8R69MI= AM-YmDCMWwrEtd2Ik5GXWnNR4nffYw5SDsDng1iejStMuu8$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!75LpJpXS65MfZ9jto11_acDTk8ETi0NBYAXogL8R69MI= AM-YmDCMWwrEtd2Ik5GXWnNR4nffYw5SDsDng1ieu6wCWnI$=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) .