Extended Forecast Discussion NWS Weather Prediction Center College Park MD 258 AM EDT Sat Jun 2 2018 Valid 12Z Tue Jun 5 2018 - 12Z Sat Jun 9 2018 Pattern overview and guidance evaluation ---------------------------------------- The forecast period begins on Tuesday with an upper trough over the West Coast, a ridge axis encompassing the central U.S., and an amplifying trough over the eastern U.S. with a surface low off the New England coast. This overall synoptic scale pattern is expected to hold through much of the upcoming week, with disturbances tracking across the northern tier of the U.S. around the northern periphery of the upper ridge that will be building over the southern plains. In terms of the model guidance, the deterministic guidance has come into better agreement compared to 24 hours ago for the northeast states. By Wednesday, the CMC becomes faster than the model consensus in ejecting the upper low eastward and also shows less amplitude with the upper ridge over the central U.S. The UKMET is closest to the coast on Tuesday with the departing nor'easter. With the second surface low tracking across New England, the ECMWF is farther south whereas the GFS is displaced farther north. The models and ensemble means continue to agree well on the amplitude and persistence of the upper level ridge from the southern plains to the Midwest states. There is still model uncertainty with features crossing the northern tier of the U.S. later in the week around the ridge, and this is where confidence is less later in the period. The WPC forecast incorporated some of the deterministic GFS and ECMWF through the entire forecast, with increasing use of the ensemble means by next Friday and Saturday. Some previous WPC continuity was also used. Weather highlights and hazards ------------------------------ Precipitation can be expected from the north-central states to New England with the upper low and trough, along with a surface low developing offshore. Another area of concentrated showers and storms is expected across the Dakotas and the Upper Midwest by the middle of next week as a disturbance crosses near the Canadian border. Model guidance is also signaling possible mesoscale convective systems (MCS) developing from Oklahoma and propagating southeast in northwest flow aloft early in the week. The ridge over the South will result in a heat wave from southern California, the Desert Southwest and the southern plains. Many locations across Texas, Oklahoma and into Kansas should have afternoon high temperatures exceeding 100 degrees, with a few locations approaching 110 degrees over western Texas. Daily records for high temperature will likely be tied or broken during the upcoming week. Above normal temperatures are also expected across the Rockies and extending northward across the north-central U.S. More pleasant temperatures can be found for the Northeast U.S. and the Pacific Northwest, which will be under the influence of the upper level troughs. After an unusually warm month of May, the beginning of June appears to be below average for temperatures next week from the mid-Atlantic and extending northward to New England, with cooler northerly flow behind the low pressure system offshore. WPC medium range forecasts of 500 mb heights, surface systems, weather grids, quantitative precipitation, and winter weather outlook probabilities can be found at: http://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif http://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html http://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml http://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 D. Hamrick