Extended Forecast Discussion NWS Weather Prediction Center College Park MD 255 PM EDT Thu Jun 9 2022 Valid 12Z Sun Jun 12 2022 - 12Z Thu Jun 16 2022 ...Dangerous/Record Heat for the Southwest/Great Basin to Texas into the weekend to shift into the east-central and Southeast U.S. next week... ...Heavy rain/runoff threat from the northern Great Basin/Rockies through North Dakota Sunday/Monday... 19Z Update: The 12Z model guidance suite is in very good synoptic scale agreement through the majority of the forecast period, especially with the building upper ridge axis across the Midwest and Ohio Valley region. Some minor differences become apparent with the CMC by early next week with a more amplified solution across the East Coast region. By next Wednesday, the GFS is faster to lift the main shortwave trough out of the Northern Plains compared to the slower ECMWF/CMC solutions. By Thursday, the GFS/GEFS is displaced slightly east with the ridge axis across the Northeast U.S. and slightly faster with the arrival of the next Pacific storm system. Overall, not many changes were necessary compared to the earlier forecast issuance. The previous forecast discussion is appended below for reference. /Hamrick ---------------- ...Pattern Overview and Sensible Weather/Threat Highlights... The upper pattern over the nation will amplify into Sunday with trough development across the West Coast and over the Northeast to sandwich ridging/high heat spread from the Southwest to the south-central U.S.. Active lead low pressure systems and heavy rainfall will mostly shift offshore the East Coast by Sunday, but a wavy trailing front will settle down across the South. Amplified troughing will work inland over an unsettled/cooling West early-mid next week as ridging strongly builds through the east-central U.S. and the Southeast. An excessive heat threat under the ridge will challenge daily records. The Storm Prediction Center also has a risk for wildfires over parts of the Southwest Sunday/Monday in this pattern. Meanwhile, unsettled/wet weather will spread from the Pacific Northwest to the northern Rockies where some high elevation snows are possible. There is also potential for heavy rain with some local runoff concerns for the northern Great Basin/Rockies this weekend as deeper moisture from the Pacific advects inland. Flow downstream over northern Plains/Upper Midwest next week will favor periodic strong MCS activity with heavy downpours as a series of uncertain impulses track on the northern periphery of the upper ridge. An experimental Weather Prediction Center medium range excessive rainfall outlook has a "slight" risk area for North Dakota by Monday considering similar multi-model flow/QPF focus where antecedent conditions seem most conducive for runoff issues as per the RFCs/National Water Center. ...Guidance and Predictability Evaluation... The WPC medium range product suite was primarily derived from a composite blend of reasonably clustered guidance of the 18 UTC GFS and 12 UTC ECMWF/UKMET/Canadian along with the 01 UTC National Blend of Models (NBM) for days 3-5 (Sunday-Tuesday) before leaning on the GEFS/ECMWF ensemble means and best matched model guidance from the ECMWF/Canadian into days 6/7 (next Thursday/Friday). While complex convective details will remain uncertain into short range time scales, newer 00 UTC guidance remains in line with the overall forecast scenario in a pattern with average or better overall forecast predictability and continuity through these medium range time scales as main system amplitudes and timings have trended more in sync. Schichtel 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