Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jul 04 2025 19:22:55 FOUS30 KWBC 041922 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 322 PM EDT Fri Jul 4 2025 Day 1 Valid 16Z Fri Jul 04 2025 - 12Z Sat Jul 05 2025 ....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR WEST-CENTRAL TEXAS... ....16Z Update... ....Central Texas... A mesoscale convective system stalled over Central Texas this morning and dropped 9-12+ inches of rain for some areas over the past 12 hours, which resulted in catastrophic and deadly flash flooding. This system is expected to persist through the afternoon while slowly drifting east, with an axis of heavy rain forecast to orient itself SSW-NNE across Central Texas and drop an additional 5+ inches of rain. Out of the available Hi-res guidance, the HRRR has been handing this event the best, capturing the magnitude and position of the highest rainfall well. Any additional rainfall over areas that were hit this morning will be problematic. The highest risk area will be generally from Kerr County to Mills County where the band of heavy rain is expected to set up. Additional flash flooding is expected and will likely have significant to potentially catastrophic impacts. To address this evolving threat, a Moderate Risk area has been introduced. Dolan ....Previous Discussion... ....Central Texas... Ongoing storms associated with the mid-level remains of tropical cyclone Barry and a plume of anomalous moisture are expected to continue beyond 12Z this morning, resulting in additional heavy amounts and the potential for flash flooding. Fueled by PWs ~2 to 2.25 inches (+3 std dev above normal), the consensus of the hi-res guidance shows slow-moving storms, with heavy rainfall rates continuing this morning across portions of South-Central Texas and the Hill Country. A Slight Risk area was introduced for areas where the HREF is showing high neighborhood probabilities for additional accumulations over 2 inches. The bulk of this is expected to fall during the morning into the early afternoon, before waning and drifting east by this evening. ....Northern/Central Plains to the Upper Midwest... The overnight guidance continues to show a strong signal for widespread moderate to heavy amounts associated with training storms that are expected to develop later today. Increasing southerly winds ahead of a shortwave trough moving across the Northern Plains will draw a deep moisture plume up into the region, with PWs increasing to ~2 inches (~3 std dev above normal). Storms are expected to develop and train along a slowly-advancing cold front, supporting heavy accumulations and the potential for flash flooding. The general consensus of the guidance shows the heaviest amounts centered across southeastern North Dakota into northern Minnesota. HREF neighborhood probabilities for amounts over 2 inches are well above 70 percent across much of this region, with the HREF showing some higher probabilities for amounts over 3 inches are well. Models also show convection developing farther to the south into the Central Plains. However, the general consensus indicates these storms will be more progressive - limiting the threat for widespread heavy amounts and flooding concerns. ....Florida... Deep moisture pooling along the remnants of a stalled frontal boundary and an upper low will continue to support an environment conducive to heavy rainfall. Similar to yesterday, the models show a weak wave dropping into the western Gulf, helping to focus heavy amounts along the Sun Coast. Also similar to yesterday, the HREF is showing high neighborhood probabilities for amounts over 3 inches. However, much of the hi-res guidance has been underperforming across this area, with the coverage of heavy amounts yesterday far less impressive than what was forecast. Therefore, lacking confidence in the models, opted not to upgrade to a Slight Risk at this point, but will continue to reevaluate. ....Northern Intermountain West/Rockies... A well-defined shortwave trough and modest moisture anomalies are expected to support widespread showers and storms across the region. Some of these storms may produce locally heavy amounts, with the HREF showing high neighborhood probabilities for accumulations over an inch within the Marginal Risk area. This may produce localized flooding concerns, especially over areas of complex terrain and recent burn scars. Pereira Day 2 Valid 12Z Sat Jul 05 2025 - 12Z Sun Jul 06 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR A PORTION OF=20 CENTRAL TEXAS... ....20Z Update... Given heavy rain that fell today and the potential for continued=20 convection in Central Texas on Saturday, a Slight Risk has been=20 introduced in the Day 2 ERO. Hi-res models continue to show=20 thunderstorm potential for the southern Plains and Central Texas=20 through the day on Saturday, with potential for localized 4+ inch=20 rainfall totals. Areas of Central Texas will be extremely sensitive to additional rain as soils will be saturated and rivers are in=20 flood stage. A Slight Risk area was introduced with the afternoon=20 update and encompasses areas that have and will receive heavy rain=20 today and could see additional storms on Saturday.=20 Elsewhere, the various Marginal Risk areas were maintained with minor adjustments based on latest QPF trends from hi-res models. The largest expansion was to include more of northern Montana and=20 northern Idaho underneath the upper shortwave/low where persistent light to moderate rain could result in isolated instances of flash flooding. The Marginal Risk area in the Upper Midwest was also=20 expanded southwards into northern Missouri and now includes the=20 Kansas City metro area, which could see locally heavy rain with=20 thunderstorm activity along a cold front on Saturday. There is a=20 higher risk of flash flooding in portions of Wisconsin and the=20 Michigan Upper Peninsula, but there is not enough confidence to=20 upgrade to a Slight Risk given the progressive nature of the=20 system.=20 Dolan ....Previous Discussion... ....Northern High Plains... A well-defined shortwave trough moving across the Northwest on Day 1, will move across the northern Rockies into the High Plains, where it will interact with moisture pooling along a boundary banked along the high terrain. Strong mid-to-upper level forcing along with modest moisture anomalies will support storm development, with some potential for locally heavy amounts as these storms move east across eastern Montana and the western Dakotas. ....Upper Midwest... A deep moisture plume (PWs ~2 inches) will continue to advance east along with a well-defined shortwave trough across the Upper Midwest/Great Lakes, supporting heavy rain across the region. Some training may continue from Day 1 into Day 2, raising the threat for additional heavy accumulations and flash flooding. However, confidence in its placement is less than that in the previous day. And with some of the guidance indicating a more progressive system, and/or the focus for heavy amounts moving across Lake Superior into Canada, opted to maintain just a Marginal Risk area for now. ....Central Texas... While the models are far from in agreement, some including the ECMWF, the Canadian, and the UKMET indicate that lingering moisture and mid level energy will produce additional storms and potentially heavy amounts across portions of central Texas, including those areas being currently impacted by heavy rains. ....Southeast... The model consensus shows an area of low pressure becoming better organized and moving north along the Southeast Coast. As it does, heavy rainfall may become more of a concern across coastal sections of the Carolinas. Meanwhile, deep moisture remaining across Florida will support another day of showers and storms capable of producing heavy amounts. Pereira Day 3 Valid 12Z Sun Jul 06 2025 - 12Z Mon Jul 07 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE GREAT LAKES TO THE CENTRAL AND SOUTHERN HIGH PLAINS AND ACROSS THE EASTERN CAROLINAS... ....20Z Update... The Marginal Risk areas were maintained in the afternoon update,=20 with minor adjustments based on the latest QPF trends. The Marginal Risk area that stretches from the Great Lakes to the Central and=20 Southern High Plains was expanded to include most of southeastern=20 New Mexico where 0.25-0.5 inches of rain may fall in the vicinity of sensitive burn scar areas. For the Marginal Risk area covering=20 the eastern Carolinas, a slight northward expansion was made in=20 North Carolina to account for a minor shift in QPF placement.=20 Dolan ....Previous Discussion... ....Great Lakes to the Central and Southern Plains... A shortwave trough over the Great Lakes will weaken and move east, however deep moisture along its trailing boundary may support showers and storms from the Great Lakes back through the mid Mississippi Valley into the Plains. Mid level energy moving out into the Central Plains may help support storm development and a greater threat for heavier amounts across portions of the High Plains into Kansas and Nebraska. ....Carolinas... The models present a good deal of spread regarding the development and track of a low now forming east of the Florida coast. Regardless of development, heavy rain can be expected for at least portions of the Carolinas this period. As the forecast becomes clearer, adjustments in the placement and category of the ERO will likely be necessary. But for now, given the uncertainty, opted to maintain just a Marginal Risk covering much of the eastern Carolinas. Pereira Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-oaT4-h9kXiQOlVJr1lXDrP6Jbo-HyGAzG9LYo0zCQr7= Fgo-vz_aQKg2cZ4lyXKDaFn4Dv5G0hTdvKrcoLCkWpq7hDg$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-oaT4-h9kXiQOlVJr1lXDrP6Jbo-HyGAzG9LYo0zCQr7= Fgo-vz_aQKg2cZ4lyXKDaFn4Dv5G0hTdvKrcoLCkWYana0s$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-oaT4-h9kXiQOlVJr1lXDrP6Jbo-HyGAzG9LYo0zCQr7= Fgo-vz_aQKg2cZ4lyXKDaFn4Dv5G0hTdvKrcoLCkiqEuy9Q$=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) .