


Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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454 FXUS02 KWBC 131900 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EDT Fri Jun 13 2025 Valid 12Z Mon Jun 16 2025 - 12Z Fri Jun 20 2025 ...Multi-day excessive rainfall/runoff and severe weather threat across the north-central Plains and Midwest next week... ...Southwest U.S. to South/Southeast U.S. heat threat next week... ...General Overview... Highly unsettled weather is expected across much of the central/eastern U.S. next week as upper-level energies in a split stream pattern intersect and override frontal and warm sector boundaries with enhanced pooled moisture and instability. This will include severe weather and excessive rainfall/runoff threats. More focused corridors of moderate to locally heavy rainfall are forecast across the Mid-Atlantic Monday. Main activity refocus over the northern Plains/Upper Midwest through early-mid next week should with cyclogenesis spread across the Midwest to the East mid-later next week. A flash flood/severe weather threat is apparent across these regions. High heat will linger over the Southwest into next week, with gradually increasing hotter/muggier conditions from the south- central to Southeast U.S. mid-later next week. There is also a signal for an increase in tropical moisture/associated rainfall into especially South Texas late next week to monitor. ...Guidance/Predictability Assessment... Guidance remains in reasonably good agreement with most of the synoptic scale features and offers good pattern predictability. However, guidance continues to suffer from widespread smaller scale system and especially ample convective focus variances. Accordingly, the WPC medium range product suite was mainly derived from a blend of GFS/ECMWF/CMC/UKMET model guidance along with the compatible National Blend of Models and WPC continuity for Monday into Wednesday for mass fields. Opted to pivot to toward the 00 UTC ECENS/Canadian ensemble means at longer time scales amid growing forecast spread. These forecast systems seem best compatible and downplays/delays GFS/GEFS tropical rainfall into Texas and the western Gulf Coast later next week without better support from the NHC. ...Weather/Hazards Highlights... It generally remains the case that highly unsettled weather will remain in the forecast across much of the central/eastern U.S. throughout next week as numerous expected embedded impulses in the upper-levels override frontal boundaries with seasonable moisture in place. Uncertainty remains with the specific day-to-day details given the short-wave energies, frontal placement, and likely mesoscale boundaries from prior days` storms driving new development each day, but a few more focused corridors are apparent. First, another round of thunderstorms is expected through portions of the Mid-Atlantic Monday (day 4) as a quasi- stationary boundary remains draped through the region and precipitable water values remain high. While storm coverage/rainfall amounts look to be lower compared to prior days, wet antecedent conditions and potential for additional storms support maintaining a Marginal Risk in the day 4 ERO that has been shifted to the south given latest guidance trends. Another focus will be across the Northern Plains/Upper Midwest with daily thunderstorm chances along a couple frontal boundaries. A Marginal Risk has been maintained for the day 4 period with areas of moderate to locally heavy rainfall expected throughout the region. Then, on Tuesday (day 5), a greater threat is apparent across portions of the Upper Midwest as QPF shows the potential for several inches of rainfall with more widespread/potentially organized convection, and a Slight Risk ERO has been shifted slightly southward. This region will have also experienced several days of rainfall prior to the day 5 period, so antecedent conditions should remain wet. Storms in this region may also bring an ample severe weather risk as per SPC, including the potential for damaging winds with any organized convection. Expect the focus for storms will begin to shift south and eastward Wednesday- Friday with eastward movement of upper- troughing/associated surface frontal boundaries and upper- level ridging beginning to build in over the central U.S. There are also growing signals for an enhanced tropical moisture feed from the Gulf to northeast Mexico and South Texas in a week to monitor for signs of system development out from the Bay of Campeche/vicinity. Expect above average temperatures across the Intermountain West and adjacent portions of the Plains and Southwest to persist through next week with mean upper-ridging in place. Some more locally intense heat is apparent across portions of the Southwest into the southern High Plains Monday-Tuesday as highs rise into the low to mid-100s. Temperatures will generally remain near late Spring/early Summer averages across the eastern U.S. early next week with unsettled conditions given the upper-flow pattern. Some cooler, below average temperatures are forecast on Monday for the Mid- Atlantic region as the area remains to the north of a lingering frontal boundary. Then, during mid- to late next week, the pattern will begin to become more amplified, with the storm track lifting north and upper-ridging beginning to build in from the central to eastern U.S. Conditions look to become increasingly hotter/muggier from the Plains east through the Mississippi/Ohio Valleys and into the Southeast/Mid-Atlantic. Forecast heat indices are over 100 for much of the region, with heat indices over 105 most likely for the Gulf Coast, the Lower Mississippi Valley, and along the Eastern Seaboard north through the Carolinas and into the southern Mid- Atlantic. Schichtel/Putnam Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw $$