Quantitative Precipitation Forecast
Issued by NWS
Issued by NWS
190 FOUS30 KWBC 101552 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1152 AM EDT Fri May 10 2024 Day 1 Valid 16Z Fri May 10 2024 - 12Z Sat May 11 2024 The probability of exceeding flash flood guidance is less than 5 percent... MCS across southern GA and north FL has pushed off shore with remnant stratiform left in its wake some embedded heavier rain signals along the immediate coast. Further west, trailing low-level convergence pattern in wake of the MCS has allowed for a line of thunderstorms to impact the Panhandle, but the current rates are well-below FFGs for the hourly exceedance intervals. Modest recovery will occur this afternoon with widely scattered showers and thunderstorms initiating over north FL, but peak rates will be capped around 1-1.5"/hr, at best. This is well shy of the necessary rates for flash flood potential, and with coordination with the local WFOs, have opted to remove the MRGL risk and maintain a CONUS-wide "Nil" ERO for the rest of the period. Kleebauer Day 2 Valid 12Z Sat May 11 2024 - 12Z Sun May 12 2024 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF THE SOUTHERN HIGH PLAINS INTO SOUTH-CENTRAL TEXAS... ...Summary... Vigorous upper level shortwave trough moving slowly across the Four Corners region and southern Rockies will lead to a quick influx of deep-layer forcing and moisture across the southern High Plains in eastern NM, much of the TX Cap Rock-Rolling Plains, and into the TX Hill Country/South-Central TX. The Marginal Risk of excessive rainfall from yesterday`s Day 3 ERO was expanded across these areas based on the latest guidance trends, where the potential exists for isolated instances of flash flooding. ...Eastern NM into portions of Western and Central TX... Ahead of the approaching upper shortwave trough, a gradual uptick in difluence aloft will ensue across the outlook area. Strengthening low-level moist S-SE inflow will also take place Sat- Sat night along and east of the dryline, as 850 mb moisture flux anomalies peak between 2-3 standard deviations above normal. Convection forming off the terrain will obtain quite a bit of forward propagation given the strong deep-layer shear profile, therefore cell training is not a concern per the simulated reflectivity guidance form the models. However, available deep- layer instability (MUCAPEs at least ~1000 J/Kg over the northern portion of the Marginal area...1500-2500+ J/Kg south) along with PWs averaging 2 standard deviations above normal will favor maximum rain rates of 1-1.5"/hr and 1.5-2.0"+/3hr underneath the strongest cores. Supported by the latest CSU ERO first guess guidance, runoff from these stronger storms will pose an isolated or localized risk for flash flooding, even with the antecedent dry soils over parts of the outlook area. Hurley Day 3 Valid 12Z Sun May 12 2024 - 12Z Mon May 13 2024 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF CENTRAL AND EASTERN TEXAS INTO MUCH OF LOUISIANA AND SOUTHWEST MISSISSIPPI... ...Summary... Mid-upper level trough traversing the Central-Southern Plains north of the Red River will lead to a surge of deepening instability and moisture from the western Gulf of Mexico as a warm front pushes into eastern TX and southwest LA. Favorable dynamic and thermodynamic profiles will result in widespread convection across central-eastern portions of TX into parts of the Lower MS Valley, where a high-end Slight Risk of excessive rainfall is anticipated Sunday and Sunday night. ...Central-Southern Plains and Portions of the Lower Mississippi Valley to the Mid-Upper TX and western LA Gulf Coast... For now at least, just a modest kinematic response is noted from the guidance during day 3 ahead of the the approaching shortwave. 850 mb wind anomalies for instance are currently modeled to be around 1-1.5 standard deviations above normal (while at the same time 850-700 mb moisture flux anomalies top out between +2-2.5). The absence of a a more robust subtropical jet streak is the likely culprit; however, the presence of the 90-100 kt upper jet streak traversing the Southern Plains and TN Valley will be felt by way of subtle right-entrance region forcing (focused area of upper divergence/deep-layer ascent and low-level frontogenesis). This will enhance the fgen along the leading edge of the surface warm front, while also retarding it`s east-northeastward motion. Largely elevated, convection will become more widespread downwind of the warm front in a favorable deep- layer warm/moist advection pattern off the western Gulf of Mexico. The lingering low-level frontogenesis/slow progression of the surface front will allow for some cell training, especially across parts of central-eastern TX which had received quite a bit of rain over the past week. Over this region eastward through central LA and southwest MS, feel the ERO risk will be more of a "high end" Slight (i.e. at least 25% risk of rainfall exceeding FFG within 25mi of a point). 00Z models show pockets of 3-5+ inches of rain during day 3 within this area, with the past 2 ECMWF and UKMET runs consistently wetter than the other models. Hurley 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