FOUS30 KWBC 050059 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 759 PM EST Wed Nov 4 2026 Day 1 Valid 01Z Thu Nov 05 2026 - 12Z Thu Nov 05 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF SOUTHEAST FLORIDA, THE SOUTHERN APPALACHIANS, AND SOUTHEAST COLORADO... A Marginal risk was maintained from north GA into the southern Appalachians. There has been a recent uptick in convective intensity from far northern GA into eastern TN, and recent HRRR runs indicate some brief training of cells is possible over the next several hours as the front moves slowly eastward. Rainfall totals locally exceeding 2" could result in isolated runoff issues. A small Marginal risk was added to southeast CO. An upper low moving overhead combined with strong low level convergence will result in a narrow axis of slow moving convection from ~02z-08z. Not much instability here, but just enough to support some locally heavier rates initially, with the rain becoming increasingly stratiform as instability erodes. REFS guidance indicates localized totals of 1-3", and a good chance that 3hr FFG is locally exceeded. Not expecting widespread or high end impacts, but given the wet antecedent conditions, this FFG exceedance could be enough to result in a few minor flood impacts. The Marginal was maintained over southeast FL. Overall this is a low end threat and not expecting much convective coverage. However, any cells that do form will still be capable of heavy rainfall rates, and a highly localized flash flood risk may still exist overnight. Chenard Day 2 Valid 12Z Thu Nov 05 2026 - 12Z Fri Nov 06 2026 The probability of rainfall exceeding flash flood guidance is less than five percent. Bann Day 3 Valid 12Z Fri Nov 06 2026 - 12Z Sat Nov 07 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR SOUTHERN NEW ENGLAND... 2030Z Update... Mainlined the Marginal risk area for a portion of southeast New England on Friday. Numerical guidance continues to depict a stripe of 1.5 to 2.5+ inches of rainfall along and to the east of a cold front making its way across the region. Even though there was a bit of an eastward shift in the rainfall axis...it was not enough to preclude westward shifts with time so the outlook area largely remained unchanged from the overnight issuance. Bann Previous Excessive Rainfall Discussion... Only minor tweaks were made to the inherited Marginal Risk area for southern New England, NYC and Long Island on Friday. There remains considerable uncertainty as to where the western edge of the rain shield will be, with the best forecast looking like it will be right over NYC and the lower Hudson Valley. A wave may try to push the plume of heaviest rain west across NYC Friday afternoon, before the rain shield wraps up and pushes everything east out to sea. There's more certainty that eastern Long Island through southern New England will be stuck in the axis of heaviest rainfall for much of the period. Despite a prolonged period of dry weather going into this event, as well as limited instability generally sub-500 J/kg, PWATs around 1.5 inches, urban, and upslope enhancement should work to cancel those out. This will result in isolated instances of flash flooding in urban and poor-drainage areas. Any additional eastward shifts in the plume would remove the NYC metro from the Marginal with future updates. Wegman Day 4 and Day 5 Valid 12Z Sat Nov 07 2026 - 12Z Mon Nov 09 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF SOUTHERN TEXAS THIS WEEKEND... Model guidance is beginning to converge on a synoptic evolution that would favor areas of heavy rain over southern TX this weekend. A mid to upper low is forecast to dive southeast out of AZ and into northern MX late Friday, and then progress eastward towards West TX by Sunday. This feature will provide ample ascent for rainfall, with a strong upper level jet providing additional lift. Anomalous moisture will advect northward ahead of this system, and while PWs will likely not be as high as recent events, it is still forecast to exceed the climatological 90th percentile. In the low levels we should have east to northeasterly flow, which will aid in isentropic ascent over the region, but should also act as a stabilizing factor. Thus the degree of instability, which will impact rainfall rates and the flash flood potential, remains a question. What was large model spread in the evolution of the closed low has shrunk with the 12z suite of models. The AIFS has generally been the most persistent model showing the heavy rainfall threat, but at 12z the ECMWF/GFS/AIGFS all trended in this direction as well. So while some additional model fluctuations can be expected, there is enough agreement to go with a Marginal risk at this time. If/where sufficient destabilization is able to occur to drive higher rainfall rates, a future Slight risk upgrade may be necessary. Best chances for this at the moment appear to be along the south TX coast where instability advecting in off the water and coastal convergence could focus higher rainfall magnitudes. Chenard 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 $$