Day 1
Valid: 01Z Mon Oct 05 2026 - 12Z Mon Oct 05 2026
THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE LOWER TEXAS COAST & SOUTHEAST
Lower Texas Coast
While a small area of thunderstorms moving down the intracoastal between is fading, other activity in the Gulf appears to be heading into the region. Both the 12z REFS/18z HREF indicate heavy rain potential overnight within a very moist air mass in an environment where 500-2000 J/kg of ML CAPE remains present. There`s not enough of a signal for a Moderate Risk any longer, so downgraded the risk to a Slight as a course of least regret. Hourly rain amounts to 3" are possible overnight.
Southeast U.S
Due on ongoing convection across portions of southeast LA, AL, MS, southern SC/adjacent GA, as well as an overnight/early Monday morning uptick in convection expected near the Central Gulf Coast within a regime of onshore flow, a Slight Risk remains across portions of the Southeast. Coverage of all risk areas has been pared back to account for recent radar reflectivity trends and trends in the 12z REFS/HREF guidance. Hourly rain amounts to 3" are possible within the moist and unstable air mass present, and recent days of rain have partially saturated area soils, so still believe a high-end Slight Risk is reasonable for far southeast LA and portions of the FL Panhandle.
Roth
Day 2
Valid: 12Z Mon Oct 05 2026 - 12Z Tue Oct 06 2026
THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE LOWER TEXAS COAST
Texas Coast
20Z Update: Current trends in guidance have increased confidence in a locally enhanced area of flash flooding potential with a positioning over more of the urban corridor in the lower Rio Grande Valley (RGV) compared to the current D1. Models have picked up the signal with a relative maxima positioned over Willacy and Cameron counties, including the city of Brownsville and surrounding urban corridor located between McAllen to Brownsville proper. HREF and REFS blended mean QPF is right around 5-8" over the region, albeit falling over an entire period, meaning scattered flash flood prospects likely with potential for more significant flash flood scenarios pending training of heavier cells located in the region.
The flow will remain persistent out of the east-northeast allowing for pivoting bands to rotate back over the same areas for hours before they subside. PWAT percentiles remain closer to the 99th percentile according to the latest ECENS and NAEFS probabilistic outputs for all of Deep South TX. This points to a maintenance of the SLGT risk with a non-zero chance at a future upgrade if guidance/radar trends warrant.
Kleebauer
Previous Discussion
A surface front will track southward into the Gulf Sunday and linger along the Lower Texas Coast Monday. While the accompanying ribbon of instability may be quite compressed by Monday, PWs as high as 2.5" and deep warm cloud depths will maintain a favorable thermodynamic environment for heavy rainfall. Additionally, an axis of 700-500mb deformation just offshore will arc back towards the region, resulting in a narrow corridor of enhanced ascent to drive streaks of convection with heavy rain. The HREF (when available) and REFS both indicate a 20-30% chance of rainfall rates exceeding 2"/hr, which through training thanks to continued anti-parallel Corfidi vectors may produce an additional 3-5" with locally higher amounts (REFS/HREF 5"/24hr probabilities above 60%). For this reason a SLGT risk has been added for a narrow corridor of the BRO CWA.
Weiss
Southeast
20Z Update: The overall forecast remains consistent with the latest guidance outside some small adjustments on the northern fringe of the inherited MRGL risk. Models and latest observations in the current D1 relay a theme of the frontal progression being a little faster and the wedging east of the Appalachians digging a bit further south into GA during the D2 time frame. HREF and REFS probabilities for >3" are highest within bounds of the front, especially in the coastal areas of FL where 50-80% probabilities for the threshold are present along the northeastern FL coast, including the Jacksonville to St. Augustine area. Main threat will continue to be the urban centers and areas with a history of poor drainage. PWATs will continue to reside above 2" for much of FL into southeastern GA, however with the frontal progression, the best threat for heavy rain >2" will reside over north FL as noted via the hourly rate probabilities from both hi-res ensembles (HREF/REFS) between 20-50% on an areal average during the forecast cycle.
Kleebauer
Previous Discussion
A similar environment persists farther east along the Gulf Coast from the Florida Panhandle and extending northeast into coastal South Carolina. A cold front will be drifting slowly southeast across this area as height falls south of an expansive mid-level trough inexorably work their way south towards the Gulf Coast. Weak impulses moving through the flow aloft will help generate waves of low pressure along this front, and where these waves move northeast they will enhance the rainfall through locally accelerated flow and stronger ascent. Regardless, efficient rainfall rates of 2-3"/hr are likely within a plume of exceptional tropical moisture (PWs above 2.25") and deep warm cloud depths. Considered a SLGT risk where the guidance supports areas of heavier rainfall, but there continues to be some uncertainty as to how much instability will persist north of the front (depending on how far south it progresses), and anafrontal rainfall may not be heavy enough for a SLGT risk upgrade. While training is likely along the CAPE gradient which through these rain rates could lead to 2-4" of rain atop saturated soils from D1, opted to maintain the MRGL risk at this time due to this uncertainty. However, a SLGT risk upgrade may be needed if signals continue to support another day of heavy rain on Monday.
Weiss
Day 3
Valid: 12Z Tue Oct 06 2026 - 12Z Wed Oct 07 2026
THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR MUCH OF FLORIDA AND SOUTHEAST GEORGIA
20Z Update
Minimal changes necessary for the D3 time frame. Models continue to signal isolated instances for flash flooding across north-central FL, as well as the coastal areas between St. Augustine down towards Port St. Lucie. Main concerns will be within those urban centers where flash flooding over the impervious surfaces creates the most issues historically. Ensembles across the region north of I-4 are between 1.5-2.5" in the means with the environment more than capable convective development due to the convergence axis near the front and the general buoyancy thanks to the lingering tropical airmass over the region.
Kleebauer
Previous Discussion
The cold front from Monday will stall across the northern Florida Peninsula Tuesday as a stationary front. This front will meander subtly north/south through D3, remaining entrenched within weak mid-level flow and a plume of anomalous PWs progged to be over 2.25", or above the 97th climatological percentile according to NAEFS. Weak mid-level shortwaves traversing slowly atop the boundary will enhance ascent, and despite modest instability, the overlap of sufficient ascent within the deep tropical moisture will result in yet another day of heavy rain as convection trains WSW to ENE on 0-6km mean winds parallel to the boundary. With rain rates expected to reach 1-2"/hr, at least isolated flash flood impacts are expected, especially where rain moves across areas that also experience heavy rain on D2 /Monday./ Effective bulk shear of 20-30 kts may support some modest organization which could enhance the risk to drive a targeted upgrade to a SLGT risk, but at this time maintained the MRGL risk due to uncertainty in the intensity and footprint.
Weiss
Day 4 and Day 5
Valid
12Z Wed Oct 07 2026 - 12Z Fri Oct 09 2026
THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE GULF COAST & TEXAS BIG BEND
A stationary surface front will remain draped roughly halfway across the FL Peninsula Tuesday through Thursday and will continue to be a focus for potentially heavy rainfall through at least Wednesday night. The axis of highest PWs (2.25-2.5") and mid- level shortwave energy will be be in the front`s vicinity, as well as instability from the nearby Gulf. Deep west/west- southwesterly flow will enhanced the risk for training cells coming off the eastern Gulf across central FL, while anti- parallel flow to the front`s north across northern FL bringing in instability from the subtropical Atlantic and could lead to very high precipitation efficiency. Effective bulk shear values over 20kts would allow for some degree of organization on Wednesday. Hourly rainfall amounts to 3" should be possible given the available ingredients. In the TX Big Bend, enough moisture and instability could be present for an isolated flash flood possibility, which led to a new Marginal Risk area. Hourly rain amounts to 2" are possible given the available ingredients there.
On Thursday/Thursday night, the guidance shows the front across FL becoming broader as the subtropical ridge begins to build across the FL Peninsula. Meanwhile, enough Gulf moisture/instability flirts with portions of southeast LA, Padre Island TX, and the TX Big Bend Thursday into Thursday night to lead to occasional heavy rainfall signals in these areas. Changes were minimal to the Wednesday/Wednesday night Marginal Risk area, mostly confined with expansion near the eastern border of FL/GA. For Thursday/Thursday night, Marginal Risks were added for southeast Louisiana, Padre Island TX, and portions of the TX Big Bend. Much like the previous day, hourly rain amounts to 3" are possible near sections of the Gulf Coast given the available ingredients and 2" for portions of the TX Big Bend.
Roth
Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt
