Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 03 2025 08:11:16 FOUS30 KWBC 030811 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 411 AM EDT Thu Jul 3 2025 Day 1 Valid 12Z Thu Jul 03 2025 - 12Z Fri Jul 04 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN PORTIONS OF THE FLORIDA PENINSULA, WEST TEXAS, AND NEW MEXICO... ....Southwest to the Southern Plains... A mid-to-upper level shortwave moving into southern California=20 this morning will move into the Four Corners region by this evening and then the central and southern Rockies overnight. The large=20 scale lift associated with the wave, along with ample moisture=20 remaining in place, are expected to produce widespread showers and thunderstorms across Arizona and New Mexico. A Slight Risk was=20 maintained across the eastern New Mexico and West Texas mountains=20 into the High Plains, where additional storms are expected to=20 develop across the same areas that have received several rounds of=20 storms and periods of flash flooding over the past several days. A=20 Marginal Risk was maintained farther to the north into the central=20 Rockies, extending into parts of southern Wyoming, where the=20 overnight guidance continues to indicate the potential for=20 localized heavy amounts as the deeper moisture is drawn northward=20 ahead of the advancing shortwave. While differing in the details, the models continue to show a notable signal for more widespread heavy amounts developing further east into parts of central Texas. Continued to extend the Slight Risk from eastern New Mexico and West Texas out into parts of Northwest Texas and the Hill Country. Persistent southerly flow will support a widespread area of PWs AOA 2 inches (+3 std dev), supporting the potential for heavy amounts. The Slight Risk was drawn to include areas where the 00Z HREF showed high neighborhood probabilities for amounts of over 2 inches, with notable probabilities for amounts of 3 inches as well. ....Eastern Oklahoma to central Louisiana... A slow-moving returning boundary is expected to become the focus for deeper moisture (PWs ~2 inches), which along with daytime heating and modest mid-to-upper level forcing, is expected to produce a swath of slow-moving storms later today, capable of=20 producing heavy rainfall rates and accumulations. The overnight=20 HREF shows a decent signal for some locally heavy amounts,=20 especially from central/southeastern Oklahoma through the ArkLaTex into central Louisiana. Neighborhood probabilities for amounts=20 over 2 inches are above 50 percent across this region. Given the relatively high FFGs covering much of this area, opted to introduce just a Marginal Risk area at this time. ....Southeast...=20 Not much change from the previous outlook, with heavy rain=20 associated with a slow-moving wave developing along the trailing=20 end of a front settling along the Gulf Coast. Supported by onshore flow ahead of the wave as it develops neat the Florida Big Bend=20 and drops south, the heaviest amounts are still expected to focus=20 along the Sun Coast. HREF neighborhood probabilities for amounts=20 above 3 inches are well above 50 percent across this region.=20 Therefore, the Slight Risk was maintained. Guidance continues to=20 show a sharp gradient further inland. Therefore, just a Marginal Risk was maintained across much of the remaining peninsula and=20 further north along the Southeast Coast. ....North Dakota/Northwest Minnesota... Storms are expected to develop later this evening across North Dakota along a slow-moving warm front and ahead of a subtle shortwave moving into the High Plains. Southerly flow is expected to support an uptick in PWs (~1.5 inches). While widespread heavy amounts are not expected, models do show some potential for locally heavy amounts, bolstered by a period of slow-movement followed by=20 training cells. A Marginal Risk was introduced for the area where=20 the HREF showed high neighborhood probabilities for amounts over an inch. The HREF indicates the greater threat for heavier amounts=20 centers over northwestern North Dakota, where slow-moving storms at the onset may produce locally heavy amounts. The HREF shows some=20 modest probabilities for amounts over 2 inches across this area. ....Wisconsin... A Marginal Risk was also added over portions of Wisconsin, where a downstream portion of the previously noted front will become a focus for deeper moisture and slow-moving storms tonight. The signal for heavy amounts and potential flash flooding is a little greater across this area. Amplifying southwesterly low level inflow will support PWs climbing to ~1.5-1.75 inches, which along with a weak shortwave moving across the top of an upper ridge, will support storm development. Guidance indicates slow storm movement, with some backbuilding, supporting the potential for locally heavy amounts. The HREF shows neighborhood probabilities as high as 50 percent for amounts over 2 inches centered over northwestern Wisconsin.=20 =20 Pereira Day 2 Valid 12Z Fri Jul 04 2025 - 12Z Sat Jul 05 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF EASTERN NORTH DAKOTA AND NORTHWESTERN MINNESOTA... ....Northern/Central Plains and Upper Midwest... A much stronger signal for heavy amounts and possible flash flooding is expected to unfold across parts of eastern North Dakota and northwestern Minnesota late Friday into early Saturday. Southerly winds ahead of a shortwave trough lifting northeast into the Northern Plains will support PWs climbing to ~2 inches (+2 to=20 3 std dev). Storms are expected to develop by late afternoon and=20 train southwest to northeast ahead of a slowly advancing cold=20 front. With the HREF indicating that 12-hr amounts (ending 00Z Sat) are likely to exceed 2 inches in some locations, a Slight Risk was introduced across parts of eastern North Dakota and northwestern=20 Minnesota. A Marginal Risk was maintained farther to the south into parts of the Central Plains where convection developing over the=20 High Plains during the afternoon is expected to advance more=20 steadily east, limiting the heavy rainfall/flooding threat. ....Southern Plains... While the better forcing is expected to lift to the north, plenty of moisture will remain (PWs ~2 inches), fueling the potential for additional storms and heavy amounts. A Marginal Risk was introduced across portions of Northwest Texas into Southwest Oklahoma - centered where some the guidance shows at least locally heavy=20 amounts.=20 ....Northern Rockies... A Marginal Risk was maintained across parts of Idaho, western=20 Montana, and northwestern Wyoming, where widespread light to=20 moderate, with embedded locally heavy amounts are expected. A well- defined shortwave trough along with fairly anomalous PWs (+1 to 2=20 std dev) are expected to support locally heavy amounts and an=20 isolated flash flooding threat. ....Florida... The environment will remain favorable for widespread rain and at least locally heavy amounts across much of the peninsula, with some areas possibly seeing additional amounts over 3 inches. While an=20 upgrade to a Slight Risk may be forthcoming, model spread remains=20 fairly significant, and therefore maintained just a Marginal Risk=20 for now.=20 Pereira Day 3 Valid 12Z Sat Jul 05 2025 - 12Z Sun Jul 06 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE UPPER MIDWEST AND THE SOUTHEAST... ....Upper Midwest... Heavy rain developing Day 2 will continue well into Saturday as the previously noted shortwave and preceding axis of deep moisture advance from the Northern Plains into the upper Great Lakes. Model show PWs at or above 2 inches extending as far north as the=20 Minnesota Arrowhead and the Michigan U.P. With some signal for training storms to continue, an upgrade to a Slight across some parts of the region may be forthcoming if the signal persists and the models start to show greater agreement. ....Southeast... With the aforementioned wave expected to move out along the Southeast Coast, a Marginal Risk was maintained from coastal Georgia to southeastern North Carolina, where the threat for heavy rains is expected to increase. A Magical Risk was also maintained along the west coast of Florida along the trailing inflow and axis of high PWs. Pereira Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7OieJFqji5UeCi9IHEjOeQvej40AcsHhKnRdzJWqmt9p= wkEaRPagPL8y2BJG0SOugm6e-h2vk_k7s-NR-Yik4nIpCY8$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7OieJFqji5UeCi9IHEjOeQvej40AcsHhKnRdzJWqmt9p= wkEaRPagPL8y2BJG0SOugm6e-h2vk_k7s-NR-YikTFEVSN4$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7OieJFqji5UeCi9IHEjOeQvej40AcsHhKnRdzJWqmt9p= wkEaRPagPL8y2BJG0SOugm6e-h2vk_k7s-NR-YikLdOKLJI$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .