FOUS30 KWBC 010823 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 423 AM EDT Wed Jul 1 2026 Day 1 Valid 12Z Wed Jul 01 2026 - 12Z Thu Jul 02 2026 ..THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER THE UPPER MIDWEST... Upper Midwest and Upper Great Lakes Regions... Broad southwesterly flow aloft over much of the central third of the country will persist...continuing to draw an unstable airmass northward into the Upper Midwest and Upper Great Lakes region while shortwave troughs embedded within the larger scale flow pattern transit the area. A sharp theta_E gradient oriented along a cold front that will bisect the region from west-southwest to east- northeast across southern Minnesota into Wisconsin helping to focus convection capable of producing localized rates of 1-2"/hr as noted via the modest hourly rate probabilities from the 12z HREF. Northeast US... Tightened the previously issued Marginal risk area based on trends in radar and satellite imagery of convection in the overnight- hours prior to the start of the Day 1 period. The potential for locally heavy rainfall rates/amounts should be tapering off through the morning. Southeast Florida... A small Marginal risk area was maintained with few changes made to the changes introduced on Tuesday afternoon. Hi-resolution models and ensembles remained pretty aggressive with their solutions across the highly urbanized corridor of the southeast peninsula with neighborhood probabilities for >3" locally and even some relevant probs (30-50%) for >5" within the latest HREF output. This allowed for maintaining the Marginal risk area. Convergence pattern across the southeast FL coast is pretty well-documented as this point in the convective allowing models, so there will likely be an area that receives appreciable rainfall in the region. Whether that settles over an urban zone or not will dictate the ...Louisiana... Inverted trough will maneuver around the southern periphery of a strengthening ridge positioned to the north leading to an increasing convergence pattern across the southern half of Louisiana today and tonight. The blended QPF from both the HREF and RRFS output both push closer to 2- to 3-inches across the coastal portions of southwest/south central Louisiana. Probabilities for >3" locally are up to 40-70% within that zone along the interstate with some lower end probs for even >5" showing up between Lake Charles and Lafayette proper in the latest update. One positive in this setup is the area FFG's for all 1/3/6hr thresholds are very high given the drier antecedent soils remaining over the area. This should curb a more enhanced flash flood scenario, but still offer a modest prospect given the heavy totals in the deterministic outputs. Bann Day 2 Valid 12Z Thu Jul 02 2026 - 12Z Fri Jul 03 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE UPPER MIDWEST... ...Northern Plains/Upper Midwest/Great Lakes... Models maintain a general convective threat across much of the Upper Midwest into the far western Great Lakes region on Thursday as the synoptic pattern continues to promote persistent northwesterly flow around the northern periphery of a strengthening upper ridge positioned across the Eastern U.S. The general area of convection from the Dakotas southwestward into parts of Iowa and Wisconsin. The threat for isolated instances of flash flooding as models have QPF maxima littered across this axis. There could be an instance where heavy rainfall intersects areas hit the previous period and offer a better opportunity for flash flooding, however judgment on any targeted upgrades would need to be assessed after the previous period's rainfall. Given that and some of the QPF totals from the higher resolution guidance, did opt for a Slight Risk area. West Texas... Models depict another another round of isolated to widely scattered thunderstorms during the late day and evening convection across West Texas and a small portion of neighboring states on Thursday. The RAP depicts MUCAPE values peaking over 2500 J per kg which should help support locally intense rainfall rates. Bann Day 3 Valid 12Z Fri Jul 03 2026 - 12Z Sat Jul 04 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER THE UPPER MIDWEST TO THE WESTERN GREAT LAKES REGION... The Upper Midwest remains the focus for showers and thunderstorms as a cold front approaches the region from the north...although it is a split decision whether NCEP operational runs will verify with their northern solutions or the ECMWF will verify with its more southerly solution...and whether the MCV generated by the NAM is strong enough to sweep out the deep moisture or if GFS and UKMET are correct to keep precipitable water values around 2 inches. Introduced a Slight Risk where there was some agreement for placement of the QPF. That roughly corresponded to the placement of 2500 to 4000 J per kg MUCAPE from the RAP and more than enough instability to support locally intense rainfall rates. Bann Day 4 and Day 5 Valid 12Z Sat Jul 04 2026 - 12Z Mon Jul 06 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL STRETCHING FROM THE NORTHERN/CENTRAL PLAINS, EAST INTO THE MID MS VALLEY, OH VALLEY, LOWER LAKES AND NORTHEAST... The mid to upper level flow will become predominantly westerly from the Northern/Central Plains, eastward across the Mid to Upper MS Valley, Lower Lakes into the Northeast during the day 4/5 period. A west to east oriented front expected to lie on the southern edge of the westerlies in an axis of above average PW values, 1 to 2 standard deviations above the mean. Confidence is low with qpf details, but higher for potential of locally heavy rains in the vicinity of this front/above average PW axis and axis of instability. With the low level flow expected to be out of the west and parallel to this frontal zone, there will be potential for a period of training of cells each day in the vicinity of this front. At the moment, the risk level has been kept at marginal given the uncertainties. The bread marginal risk areas were drawn to encompass the model qpf spread, which is fairly large at this time range. Oravec 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 $$