FOUS30 KWBC 011545 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1145 AM EDT Wed Jul 1 2026 Day 1 Valid 16Z 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... 16Z Update: The SLGT risk forecast remains consistent with little change from the previous update as the synoptic pattern evolution maintained general continuity with the latest 12z deterministic. HREF mean QPF from northern IA up through southeastern MN into WI still points to an areal average of 2-3" with local spots of 4-5" plausible through the course of the period. Radar already has trended towards the favorable heavy precip axis aligned from southwest to northeast from eastern NE up through north-central WI with a flash flood warning already in place between along the southeast MN/WI border. 12z surface analysis reflected a quasi- stationary front situated from NE through northern IA into southeast MN, extending north through WI. A few surface impulses are migrating northeast along the front, aided by a quick-moving shortwave traversing the region allowing for ample low to mid-level ascent within the deep moisture pool and modest instability presence over the Midwest. This current shortwave will eject northeast into the northern Great Lakes, but a trailing mid-level vorticity maxima will enter the area by this evening allowing for a secondary pulse of convection across the same areas impacted this morning. HREF probs for >3" remain elevated for the area located between central IA, northeast into north-central WI, a correlation for where heavy precip will overlap with both disturbances within the confines of the persistent front in the region. Expectation is for a large area of 2-3" with local spots between 4-6" likely over the course of the D1. In this case, there was little reason to deviate from the previous forecast, so the SLGT risk was generally maintained with only minor adjustments on the northern and southern flank of the risk. Southwest Texas... 16Z Update: A weak mid-level impulse will continue to move from south to north through the western flank of a broadening mid-level ridge positioned over the eastern CONUS with the primary impact of scattered slow-moving convection likely to impact portions of southwest TX this morning into the early afternoon before dissipating. A second round of convection will materialize later this evening over the terrain as the combination of diurnal destabilization and weak kinematic forcing will aid in initialization of thunderstorms from the eastern NM plains down through southwest TX. Redevelopment of a modest LLJ between 25-35kts will also play a factor in maintaining sufficient shear and propping up any mature mesocyclones that materialize within the buoyant environment present. PWAT anomalies remains upwards of +2 standard deviations according to the latest ECENS and NAEFS ensembles, a signal prevalent for locally enhanced rainfall rates across the region, allowing for a better risk of flash flooding. Considering the nature of the current convection providing opportunity for multiple flash flood warning issuances and another round anticipated this evening, a SLGT risk was added across much of southwest TX in coordination with the local Midland/Odessa WFO. Northeast US... 16Z Update: Some variability in the signal for scattered thunderstorms and isolated flash flood concerns offers a low-end threat for the potential when assessing the latest 12z CAMs. The HRRR continues to be the least bullish on the prospect with hardly any coverage at all within the span of Upstate NY into northern New England while a few of the CAMs continue to indicate more prolific convective pulses that would provide locally heavy rainfall and flash flood opportunities. HREF neighborhood probabilities for >2" of rainfall remain modest with scattered signals of 20-40% located across the above area(s). This threat is on the lower end of the MRGL risk threshold, but the prospect remains when looking into the means. As a result, maintained continuity with no adjustments necessary from the previous forecast. Southeast Florida... 16Z Update: Afternoon convection will fire along a sea breeze penetrating inland across South FL with the steering pattern likely to take cells from east to west during any convective evolution. The greatest likelihood of flash flooding continues to point to the urban center between Miami to Ft. Lauderdale and perhaps as far inland as Homestead and Florida City before heavy precip shifts into the Everglades. HREF probs for locally as much as 5" of rain continue to be modest (20-30%) with the best chance over Miami proper down through FL997 to the west of the metro. No changes were necessary from the previous MRGL risk forecast. Louisiana... 16Z Update: General forecast remains on track from the previous update as we have begun to see the northern fringes of the inverted trough analyzed off the Central Gulf coast move inland over southern LA this morning. 12z CAMs continued to pin the heaviest precip across I-10 and points south through the period with the main threat likely relegated to the urban centers located between Lake Charles to Lafayette and surrounding suburbs. Little change in the prob fields indicate consistency in the signal with just some minor fluctuations in where models have the heavier precip cores anticipated. The MRGL risk inherited was maintained with only some minor adjustments based on the 12z HREF blended mean QPF output depicting a touch higher amounts further north along I-49 and north of US190. ...Previous Discussion.. 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. Kleebauer 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 $$