Extended Forecast Discussion NWS Weather Prediction Center College Park MD 238 PM EDT Mon Jun 13 2022 Valid 12Z Thu Jun 16 2022 - 12Z Mon Jun 20 2022 ...Potent, but short heat wave moves east over the northern Plains Friday through Monday... ...Overview and Guidance/Predictability Evaluation... The upper pattern further amplifies as a strong ridge builds up the Great Plains Friday through Saturday as a trough and embedded closed low shifts southeast across northern California and a trough digs across New England with a closed low there Saturday and Sunday. This pattern promotes eastward progress of an axis of high temperature anomalies over the northern Plains Friday through Monday with a cold front ahead of the western low providing relief from west to east starting on Sunday. Notable areas of precipitation during the period will likely be with a front crossing the Northeast Friday, diurnally favored convection over the Gulf Coast and Florida, particularly for Saturday-Monday ahead of the approaching cold front, across parts of the Four Corners states with a northward surge of moisture west of the ridge, over portions of the Northwest/northern Rockies with the West Coast trough and associated surface waves/fronts. The 00Z/06Z (and now 12Z) GFS is in much better alignment with the ECMWF on timing/intensity/placement of the Northeast trough/low Friday through this weekend than prior day GFS runs. Confidence has increased in a closed low pushing southeast into New England on Saturday and lingering into Sunday before drifting east to the Canadian Maritimes. The 00Z ECMWF/ECENS is still farther west/deeper with the low lingering over New England into/through Monday. Preference there is for a general deterministic model blend Thursday night through Saturday becoming more weighed by ensemble means Sunday/Monday. For the upper trough drifting southeast off the Pacific Northwest coast before reaching northern California Friday night before drifting east through the weekend, the deterministic globals are in good agreement until about 12Z/Sat with the pivot with the 00Z CMC lingering west/drifting down the coast while the GFS and ECMWF are in decent agreement with the eastward pivot with the 00Z ECMWF more progressive than the 06Z/12Z GFS. As such, the forecast is based on a blend of 00Z/06Z deterministic guidance favoring the 00Z ECMWF through Day 5 then increasing weight to the 00Z ECENS/CMCE and the 06Z GEFS. ...Sensible Weather/Threat Highlights... The cold front progressing eastward from the Great Lakes will produce showers and thunderstorms over the Northeast and along the pivoting cold front near or over northern Missouri Thursday night/Friday with locally moderate to heavy activity possible. Best potential currently appears to be over and near the central Appalachians into the Northeast. While most areas should see a drier trend after frontal passage, increasing potential for upper troughing/possible closed low over or near the Northeast may lead to multiple days of showery weather over that region. The Southeast and Gulf Coast regions will see diurnally favored showers and thunderstorms Friday/Saturday and then over the Florida Peninsula Sunday Monday in the warm sector ahead of a stalling cold front. The upper trough reaching the Northwest coast Friday night should initially bring mainly light rainfall to parts of the Northwest, with an increase in amounts at least on a localized basis as the closed system moves inland and moisture is added from the west side of the Great Plains ridge during the weekend. Western Montana looks to see notable warm precipitation (snow levels above 10,000ft) in the Sunday timeframe. The deep-layer flow between the West Coast trough and central U.S. ridge brings a monsoon-preview with much above normal moisture for the time of year northward through the Four Corners states and vicinity (most likely eastern sections of this area) Friday through the weekend, supporting an increase in coverage and intensity of rainfall across the region. Rain/thunderstorms look to continue over this region into early next week and the moisture may interact with the front slowly advancing through the West. The eastern U.S. will see a pronounced cooling trend from the recent heat as the upper trough/low move in with below normal highs over the eastern Great Lakes/Northeast this weekend into early next week. Meanwhile heat shifts again from The West as the ridge builds north from the central Rockies through the Northern Plains Friday. A narrow axis of high temps 15 to 25F above normal shifts east from the northern High Plains Friday, reaching the Upper Midwest by Monday. Max temps over 100F are forecast with this heat wave over the northern Plains though it will be brief with about two hot days forecast. Scattered daily record highs are possible. By Sunday, a cold front ahead of the Northwest low will cross the northern High Plains before providing cooling relief to areas farther east through early next week. Southern portions of the Plains will stay on the hot side with highs 5-10F above normal through the period. High temps 10 to 15 degrees below normal will spread eastward across The West Friday-Sunday and then likely trend closer to normal by Monday based on the expected eastward progression of the western low. Jackson 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, experimental excessive rainfall outlook, winter weather outlook probabilities and heat indices are at: 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