FOUS30 KWBC 022015 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 315 PM EST Mon Nov 2 2026 Day 1 Valid 16Z Mon Nov 02 2026 - 12Z Tue Nov 03 2026 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR AREAS BETWEEN MELBOURNE AND PORT ST. LUCIE, FLORIDA... ...Florida... 15Z Special: A targeted MDT risk has been added in coordination with the Melbourne WFO due to significant rainfall and high-end impacts occurring from a convergent band of heavy precipitation over the east-central FL coast. Rainfall totals of 5-15" have fallen in a narrow corridor between Melbourne down to just north of Fort Pierce leading to widespread flash flooding in this zone, especially just south of Melbourne proper. More on this setup will be included in the official 16z update. 16Z Update: Significant rainfall continues across the east-central FL coast this morning within a narrow convergent zone on the eastern edge of a slow-moving MCV positioned over west-central FL, near Tampa. The current radar/sat composite show a swath of moderate to heavy rainfall over the central portion of the state with a narrow band of intense rainfall between Melbourne down towards Port St. Lucie. Mesoanalysis indicates weak shear centered over the eastern side of the peninsula with a prevailing east- southeast flow between the surface to 850mb, followed by a strong veering of winds between 700-300mb as the height field is dictated via a persistent trough located over the entire stretch of the state. The combination of shear and enhanced low-level convergence within the eastern periphery of the complex has allowed for a narrow corridor of repeating heavy rainfall with anchoring positioned right along the coast where the instability gradient coincides with the better effective layer shear positioned just south of the Space Coast. Recent trends in both the HRRR/RRFS have been providing an uptick in the QPF distribution as the hourly models have finally caught on to the localized setup that's caused quite a bit of trouble near Melbourne this morning. Expectation is for an additional 2-4" with locally as much as 8" plausible in this corridor along the coast, leading to a special ERO update to include a targeted MDT ~15z this morning. The threat over the coastal areas will continue through the first half of the afternoon before the setup starts to slowly breakdown and we see the threat dwindle before dissipation after 23-00z when all guidance shows the threat fizzling out. For areas inland, the convergent axis is right beneath the general MCV circulation providing a secondary maxima to the northwest of Lake Okeechobee where MRMS indicates 4-8" of rainfall already occurring in this zone, as well, leading to a flash flood warning for areas that normally don't usually see flash flooding due to very high FFG's. This just indicates the type of environment we are contending with and will continue to contend with through at least part of the afternoon. For more information on the setup and impact potential across the FL Peninsula, please see MPD #1549 for the latest. Kleebauer ...Midwest/Plains... 16Z Update: Two primary changes with the latest D1 update include an expansion of the SLGT risk further northeast to include more of northwestern MO into southern IA, as well as an additional MRGL risk across western KS up into southern NE with a narrow band of enhanced convection near the advancing cold front and trailing surface low ejecting out of the southeast CO Front Range. Models have been consistently upping the potential across the Missouri Valley into the East-Central Plains with the cold front encountering a maturing warm sector environment as our surface low moves off to the northeast and amplifies over the next 24 hours. Latest HREF/REFS mean QPF now indicates a swath of 1.5-2" areal averages from northeast OK up through southeast KS into northwest MO and far southern IA, a signal consistent with approaching at least the 3-hr FFG exceedance threshold as noted via the 12z data. Deterministic results a bit more robust with a strong signal for locally >2" (60-90%), and modest probs (25-50%) for at least 3" in the latest hi-res ensemble suite, enough to warrant the SLGT risk and expansion to cover areas within those elevated probabilities. The rest of the area encompassed by the MRGL remain pretty consistent for the current risk with only minor modifications necessary over the Mid-Mississippi Valley. Kleebauer ..Previous Discussion.. A highly-amplified and multi-stream upper trough is forecast to move east of the Rockies into the Plains today, producing widespread precipitation across the central U.S. A well-defined shortwave within the base of the trough will move from the Four Corners this morning, into the central and southern Plains by this evening. The potential for heavy rain is expected to increase this evening across portions of the southern and central Plains, especially from eastern Oklahoma and Kansas into western Missouri as a 40-50+ kt southwesterly low level jet develops ahead of the wave, supporting strong moisture advection into a region of increasing ascent. Showers and storms are expected to develop with the potential for heavy rates increasing as PWs increase to ~1.75 inches and right-entrance region upper jet forcing supports large- scale ascent. Hi-res guidance indicates that elevated storms can be expected during the late afternoon across portions of eastern Oklahoma into the lower Missouri Valley before a more robust line of storms develops and advances east ahead of a sweeping cold front. In addition to the potential for more than one round of storms, a period of training convection may elevate the risk for localized heavy amounts and flash flooding. A Slight Risk was added where both the HREF and REFS show high neighborhood probabilities for accumulations over 3 inches. Both also showed neighborhood probabilities for amounts exceeding 3-hr FFGs increasing into the 20-30+ percent range across portions of the area during 0-6Z Tuesday timeframe. Farther to the north, a Marginal Risk covering portions of the northern Plains and upper Midwest was maintained. Widespread coverage of 1-2 inch amounts across parts of the Dakotas and Minnesota is forecast. However, not expecting any widespread flash flooding concerns as limited instability will keep rainfall rates in check. Pereira Day 2 Valid 12Z Tue Nov 03 2026 - 12Z Wed Nov 04 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL PORTIONS OF MID- SOUTH... ...Lower and Mid-Mississippi Valley... 20Z Update: Only small modifications were necessary for the inherited SLGT risk across the Lower Mississippi Valley with the emphasis of flash flooding still within the zone between northern MS, southwestern TN, over into far northwest AL. The trend from guidance was to press the front a bit faster to the east leading to heavier precip axis located a bit downstream of where the previous QPF max was located. ML guidance is still highlighting the area back near the Mississippi with the max over the Mississippi Delta into southwestern TN. Secondary max showing up within the CAMs over southern AR, back towards the ArklaTex where the instability is the greatest and low-level convergence will be maximized in the afternoon hours during the maturing instability period. FFGs further southwest are running very high due to a prolonged drought in the region, so refrained from a SLGT risk expansion into this particular zone, but smaller towns across southern AR back towards Shreveport may see local flash flood prospects a bit higher compared to surrounding areas. FFG exceedance probs are still focused up near Memphis and northern MS into western TN with a potential for heavy rainfall back up to the west of Nashville. The SLGT risk was expanded a bit north of the previous issuance and bit east to account for the faster trend of the cold front advancement which correlates to heavier rainfall potential downstream. Kleebauer ..Previous Discussion.. The general consensus of the hi-res guidance shows that storms developing late Monday will remain ongoing along an advancing cold front extending from the mid Mississippi Valley back into eastern Texas Tuesday morning. There is some indication in the guidance that heavy rates and continued southwest-northeast training may elevate the threat for heavy amounts and flash flooding from the Ozark region into southeastern Missouri. This suggests an upgrade may need to be considered at some point, but for now maintained the outlook at just a Marginal Risk. Farther east, a Slight Risk centered over the Mid-South was maintained -- where deep moisture and favorable upper jet forcing are expected to support re-intensifying storms capable of producing heavy rainfall rates. The previous Slight Risk was largely maintained, but adjusted a little to reflect the REFS high neighborhood probabilities for 2-3+ inches across this area. Pereira ...Florida... 20Z Update: Mo changes to the previous forecast as the forecast remains on track from the last forecast issuance. The heavy totals the previous 24hrs will only add to the threat over the east- central FL coast as soil moisture will maintain well above normal state with the latest soil moisture percentiles already pushing above 90% for areas between Melbourne to Port St. Lucie/Stuart area. This will provide an enhanced prospect for flash flooding, even if the setup isn't as pronounced as previous periods. Heaviest rainfall within the latest 12z HREF/REFS means are a bit south compared to today's activity, so this may help limit future impacts as the best convective risk lies away from the hardest hit location. No matter the case, there is still at least an isolated threat for flash flooding with the prevailing easterly flow over the peninsula for Tuesday. Kleebauer ..Previous Discussion.. Easterly flow will weaken this period; however, with anomalous moisture remaining in place, cannot rule out additional localized heavy rainfall amounts resulting in at least isolated flash flooding concerns, especially in urbanized locations and areas previously inundated with heavy rains. Pereira Day 3 Valid 12Z Wed Nov 04 2026 - 12Z Thu Nov 05 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE TENNESSEE AND LOWER OH VALLEYS TO THE SOUTHERN AND CENTRAL APPALACHIANS... 20Z Update: Only minor changes to the previous MRGL risk with the main area of interest still aligned within the upslope area across the Southern Appalachians. A bit of an expansion of the MRGL risk over southern Ohio, as well, with some of the trends showing greater convective potential over the Central Appalachian area ahead of the cold front. Considering the more sensitive nature of the terrain in this area of the CONUS, opted to expand the risk to cover for the low-end threat. Totals generally 1-2" in the most impacted areas, but global ensembles indicate some risk of 2-3" in isolated areas which could very much cause some flash flood concerns in the region of interest. Will assess in the coming days with the additional forecasts from the CAMs, but antecedent dryness will likely curb any widespread flash flood threat, unless magnitudes increase in the coming days. Kleebauer ..Previous Discussion.. Activity developing late Tuesday may continue into the early part of the period, with a ribbon of deep moisture and favorable upper jet forcing contributing to additional heavy rates and possible flash flooding across parts of the Tennessee and lower Ohio valley early on. Storms are forecast to shift east into the central and southern Appalachians later in the day, where orographic effects may help bolster totals across parts of the region and raise flash flooding concerns, especially in the more sensitive parts of the central Appalachians. Pereira Day 4 and Day 5 Valid 12Z Thu Nov 05 2026 - 12Z Sat Nov 07 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Enough model spread remains to withhold adding any Marginal risk to the Mid-Atlantic and Northeast. Still looks like the front will stall near the coast and allow for an axis of heavier rainfall amounts. A solution such as the 12z ECMWF would probably result in at least a localized flash flood risk from the eastern Mid- Atlantic into southern New England, with 2-3" of rain and ~500 J/kg of CAPE allowing for some embedded higher rainfall rates. However, other models are further east with this axis (mainly offshore), and the degree of instability is also uncertain. Given the dry antecedent conditions we will hold off on adding a risk area until we have more confidence in an onshore rainfall axis and some overlapping instability. 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 $$