Quantitative Precipitation Forecast
Issued by NWS
Issued by NWS
668 FOUS30 KWBC 071545 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1145 AM EDT Fri Jun 7 2024 Day 1 Valid 16Z Fri Jun 07 2024 - 12Z Sat Jun 08 2024 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE CENTRAL PLAINS... ...16Z Update... General continuity from the previous forecast with some minor adjustments of the SLGT risk to account for the latest forecast QPF accompanying the expected MCS. HREF and associated CAMs are in good agreement on the axis of heaviest precip expected from this evenings MCS across the central plains into the Mid-Mississippi Valley. HREF blended mean QPF is a solid stripe of 2-4" within the zone of the MCS influence with some deterministic output entering the 4-5" range despite the progressive nature of the complex. The the reasoning is due to increasingly favorable low to mid-level moisture advection occurring this evening from a developing nocturnal LLJ that will move rich Gulf air poleward into portions of the central plains and adjacent Mississippi Valley. Probability fields are fairly robust for both total precip and potential rates with the >3" neighborhood probability settling between 20-40% over a large area encompassing southeast NE through northeast KS and northwest MO. This was slightly better than even the overnight HREF iteration, likely in part to the better agreement among the CAMs members integrated into the ensemble. The prospects for rates exceeding 2"/hr also improved with an area of 30-45% located within the same zones above, and >3"/hr within low probabilistic means (10-15%), so certainly not zero and statistically significant considering the environment. As a result, the previous SLGT inheritance was generally maintained with a focus over southeast NE through the adjacent plains states, including KS/MO. A quick note on the setup across ME....increasing ascent within the confines of an approaching shortwave rounding the upper level circulation over Ontario will induce a period of convection across northern New England with a focus on northern NH into western ME. After some collaboration with the local WFO`s within the impacted area, a MRGL risk was entertained, but deemed unnecessary for the non-zero threat of flash flooding. Area soil moisture is running tremendously below average with much of western ME experiencing a class 2 (Severe) drought according to the National Drought Monitor. Outside pockets of heavier thunderstorms anchoring to the terrain in the White Mountains and northern Appalachian front in ME that could generate isolated flooding, much of the rainfall will be beneficial in the areas encompassing. Thus, refrained from any issuance, but will be an area to monitor pending the convective evolution. Kleebauer ...Previous Discussion... The setup continues to look favorable for a heavy rainfall event across portions of the Central Plains later today through tonight. Early morning analysis showed a strong ridge of high pressure anchored over the Four Corners into Texas while over the Central Plains, northwest flow is present. Across the Northern Rockies, shortwave trough energy is noted and it`s this feature that will dive southeast into the Plains later today to help ignite a few rounds of deep convection. In the lower levels, southerly flow in response will bring northward anomalous moisture with the PWs forecast to quickly rise above 1.5" through KS into southern NE. The favorable forcing aloft with the higher moisture and expected instability will ignite the storms and then the expectation is for the storms to grow upscale into a MCS as it moves into portions of Missouri and clip southwest Iowa. The 00Z guidance has come into better agreement on the details and expected locations of the heavy rainfall, with the 00Z HREF neighborhood probabilities for at least 3 inches jumping to above 50 percent now for far eastern NE, northeast KS, southwest IA, and northwest MO with a slight (10-15 percent) chance of 5" totals. Hourly rain totals may exceed 2 inches in localized spots. The Slight Risk was adjusted minimally to the north, to adjust toward the latest guidance and probabilities where the setup for training/repeating rounds is greatest. Taylor Day 2 Valid 12Z Sat Jun 08 2024 - 12Z Sun Jun 09 2024 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF EASTERN KANSAS THROUGH SOUTHERN MISSOURI... The latest guidance continues to advertise a corridor of heavy rainfall across portions of the Southern/Central Plains eastward into the Mid Mississippi Valley as a cold front sags southward into the region and low level southerly flow pushes anomalous moisture into the boundary. Aloft, the quasi zonal flow along with an embedded shortwave trough moving through will help bring the larger scale forcing. This combination of higher moisture (PWs 1.5-2") and lift along with favorable amounts of instability forecast should support multiple rounds of thunderstorms, particularly from the late afternoon through the nighttime hours. The latest ensemble guidance members and deterministic models support potential for localized 2-3" totals and rain rates 1-2"/hr at times with the greatest potential for those higher totals over far eastern KS through southern Missouri where the Slight Risk is highlighted. Further west, moisture banking against the terrain of the Front Range combined with daytime peak heating and shortwave trough energy moving through will lead to isolated/scattered showers and thunderstorms, some of which will be slower moving and produce intense rain rates and isolated/localized flash flooding. Taylor Day 3 Valid 12Z Sun Jun 09 2024 - 12Z Mon Jun 10 2024 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF COLORADO FRONT RANGE, SOUTHERN PLAINS, AND MID MISSISSIPPI VALLEY... The wavy, slow moving frontal boundary is expected to reach portions of the Southern Plains and Mid Mississippi Valley Sunday through early Monday morning while aloft the pattern is expected to feature quasi zonal/northwest flow. An embedded shortwave trough is forecast to move through the region during the period, providing the large scale forcing for ascent. Meanwhile, higher moisture characterized by PWs > 1.5" will pool along/ahead of the surface boundary across the S. Plains into the Mid Mississippi Valley. This anomalous moisture, combined with the southward moving frontal boundary and large scale lift will support thunderstorm development early on in the period across portions of KS/MO/AR before the focus for new development shifts westward toward the TX Panhandle, western/central Oklahoma. The latest guidance supports isolated/scattered 1-2" totals (based off latest ECENS/GEFS members) and embedded higher amounts possible, especially across TX/OK where the deeper moisture overlaps best with the instability and forcing. The easterly flow will also bank the higher moisture against the terrain and lead to thunderstorm development from eastern New Mexico through the CO Front Range where slow storm motions and/or repeating rounds may lead to localized but intense rain rates/totals late in the period (00Z-12Z Mon). Taylor 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