Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jun 05 2025 15:58:07 FOUS30 KWBC 051556 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1156 AM EDT Thu Jun 5 2025 Day 1 Valid 16Z Thu Jun 05 2025 - 12Z Fri Jun 06 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTH-CENTRAL PLAINS... ....Central to Southern Plains... With scattered to widespread storms expected across much of the=20 country in an active late Spring pattern, a locally higher threat=20 for flash flooding exists over portions of the Central/Southern=20 Plains where greater coverage of heavy rainfall is expected with=20 the development of a convective system later this evening. An=20 environment very conducive to thunderstorm development will evolve=20 today as a weak triple point develops in southeastern Colorado with high moisture, instability in place south of a warm front and=20 ahead of a dryline extending southward through the southern High=20 Plains. Afternoon convection developing off the Raton Mesa/High=20 Plains will feed off the higher theta-e air and strengthening low=20 level flow ahead of the triple point into the evening hours,=20 expanding in coverage as cold pools combine/mature and with any=20 additional development eastward along the warm front. Anomalously=20 high moisture in place may lead to rain rates upwards of 2-2.5" per hour. While the system should remain progressive, the high rain=20 rates and storm coverage will bring the threat for locally heavy=20 rain totals as high as 3-4" and scattered instances of flash=20 flooding along the system path. This path is currently most likely=20 from southwestern Kansas/the Oklahoma Panhandle/the northeastern TX Panhandle later this evening east-southeast through southern=20 Kansas and northern Oklahoma into the early morning hours Friday.=20 Elsewhere, additional individual storms ahead of the dryline=20 southward through the Texas Panhandle/west Texas will also bring=20 the threat for some locally heavy downpours and isolated flash=20 flooding.=20 ....Southern Great Basin into the Southern to Central Rockies... Another day of scattered to widespread diurnal convection is=20 expected throughout the region with upper-troughing and colder=20 temperatures aloft and the presence of a lingering frontal=20 boundary. Anomalously high moisture (PWs upwards of 2-2.5 standard=20 deviations above the mean) may lead to some locally heavy downpours with rain rates of 0.5-1" bringing the threat for some isolated=20 instances of flash flooding, particularly for terrain sensitive=20 areas and burn scars.=20 ...Lower Lakes, OH Valley into the Mid to Lower MS Valley... PW values also expected to remain above average in the vicinity of the nearly stationary frontal boundary stretching from the lower=20 Lakes, southwest into the OH Valley and Mid to Lower MS Valley. A=20 broad marginal risk area was maintained from previous issuances for localized heavy rainfall and isolated runoff issues. The previous=20 marginal risk area was modified to better reflect latest model=20 consensus on the moderate to locally heavy qpf axis. ....Eastern and Coastal Carolinas... Thunderstorms continue this morning/early afternoon in a modifying airmass lifting northward through the central/eastern/coastal=20 Carolinas east of a weak surface low. Anomalously high moisture=20 values streaming in from the Atlantic (PWs 2-2.5 standard=20 deviations above the mean) and increasing instability (ML CAPE=20 around 1000 J/KG) may lead to some efficient rainfall rates of 1-2" per hour. While the heaviest rainfall is expected to remain=20 offshore and FFGs remain high, these rates may lead to some=20 isolated flash flooding concerns, particularly for coastal=20 locations that may see a few repeated rounds of storms lifting=20 northward. The threat should diminish through the evening hours as=20 the low moves offshore.=20 Putnam Day 2 Valid 12Z Fri Jun 06 2025 - 12Z Sat Jun 07 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF OKLAHOMA INTO THE KANSAS, OKLAHOMA, MISSOURI, ARKANSAS BORDER REGION... ....Oklahoma into the OK/KS/MO/Ar border area... Another round of shortwave energy forecast to drop east southeastward from the Central Rockies into the Central to Southern Plains Friday into Friday night/early Saturday. This will support potential for another round of organized convection in the vicinity of the west to east oriented frontal zone. PW values along this front will remain above average...2+ standard deviations above the mean, supporting heavy precip potential. There is fairly good model consensus for an axis of heavy rains along this front across much of OK into the OK/KS/MO/AR border region. Only some slight changes to the previous slight risk area to reflect this qpf axis consensus. ....Southern Great Basin into the Central to Southern Rockies... Not a lot of changes expected to the large scale flow from day 1 across the southern Great Basin into the Central Rockies. PW values forecast to remain above average with additional shortwave energy moving across the region in the west south west flow aloft. This should support another day of widespread scattered convection and localized heavy rain and isolated runoff issues. The marginal risk was extended back across these areas to be more similar to the day 1 period given the similar overall conditions day 2. ....Mid MS Valley, OH Valley into New England... Similar to the day 1 period, an axis of above average PW values will stretch along the slow moving front stretching from the Mid MS Valley, OH Valley into New England. There is good model consensus on a broad region of moderate to locally heavy precip amounts along this front. Only some minor changes to reflect the latest model qpf axis consensus made to the previous broad marginal risk area across these regions. Oravec Day 3 Valid 12Z Sat Jun 07 2025 - 12Z Sun Jun 08 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE LOWER ARKANSAS VALLEY, LOWER MISSISSIPPI VALLEY INTO THE LOWER TENNESSEE VALLEY... The second round of height falls moving into the Central to Southern Plains day 2 will continue to push east southeast toward the Mid to Lower MS Valley, OH and TN Valleys. Upper difluence is forecast to be well defined Saturday into Saturday night/early Sunday in an axis of above average PW values that will remain along the west to east oriented frontal boundary across these areas. This should support potential for another round of organized convection along this front. There is some spread with the qpf axes, but consensus that heavy amounts are possible along this front. The previous slight risk area was expanded eastward considerably from eastern OK, across much of AR, western TN and northern MS. ....Northern New England... A sharpening northern stream trof will push surface low pressure across northern New England on Sunday. There is fairly good model consensus for moderate to locally heavy precip totals across northern New England. Only some slight changes to the previous marginal risk area, extending it into all of northern Maine to cover the model qpf spread. Oravec Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7KqhMQi6qbPdYxvm3yANc3qcAarGkXZ1O-3QTjDk19iV= x8nbXUVeCar8tBoSPoGFA6KBgiGEOKpRFclgAk3kKORROQs$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7KqhMQi6qbPdYxvm3yANc3qcAarGkXZ1O-3QTjDk19iV= x8nbXUVeCar8tBoSPoGFA6KBgiGEOKpRFclgAk3kNSn7QQw$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7KqhMQi6qbPdYxvm3yANc3qcAarGkXZ1O-3QTjDk19iV= x8nbXUVeCar8tBoSPoGFA6KBgiGEOKpRFclgAk3kE1kz_mc$=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. 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