Extended Forecast Discussion NWS Weather Prediction Center College Park MD 211 PM EST Sun Nov 01 2020 Valid 12Z Wed Nov 04 2020 - 12Z Sun Nov 08 2020 ...Tropical Storm Eta will track slowly through the Caribbean... ...Heavy rain is possible over Florida... ...Heavy precipitation for the Pacific Northwest and wintry weather for the West/Rockies... ...Overview... The large-scale upper pattern in the medium range will begin Wed with generally zonal flow, though a shortwave should track quickly through the High Plains to the Mississippi Valley and Northeast Wed-Fri. The pattern is expected to become more amplified around Fri as a potent trough digs into the West, moving slowly eastward and deepening over the weekend, spreading precipitation to much of the West. Meanwhile, Tropical Storm Eta is forecast to move west across the Caribbean making landfall in Central America. It remains to be seen if energy from this system may be lifted north and east late in the week, potentially leading to additional tropical development, but regardless, a good amount of rain can be expected over parts of the Florida peninsula through next weekend as easterly flow persists north of a frontal system. ...Guidance Evaluation/Preferences... Model guidance was in good agreement with the pattern of initial zonal flow, the aforementioned shortwave, and troughing coming into the West. A multi-model deterministic blend from the 00Z and 06Z model guidance was able to be used for the mass fields through the middle part of the period. Models vary on how to exactly to handle the eastern U.S. east of the trough; a subtropical upper trough/low may be stationed near the Gulf Coast, disrupting otherwise ridgy flow in the East. Guidance like the 00Z ECMWF was particularly aggressive with this subtropical upper low. The evolution of Eta by late in the week also remains questionable. Some models/ensemble members have Eta crossing over Central America and reemerging over the Pacific. Some lift at least vorticity associated with Eta (not necessarily the same surface low) northeastward into the northern Caribbean toward Cuba next weekend, leading to additional tropical development there. This will continue to be monitored--use NHC forecasts for the latest information. Given the uncertainty with these features, elected to lean toward the 00Z EC and 06Z GEFS ensemble means for the latter part of today's forecast. ...Weather/Hazard Highlights... The Pacific Northwest should see a wet midweek period given moist inflow and a series of frontal passages, especially across the Cascades and Olympics and then the Northern Rockies. As the potent trough (mid-level heights 2+ standard deviations below normal) moves into the West, snow levels are expected to lower by late week as precipitation and cooler than normal temperatures overspread much of the Great Basin and Rockies and potentially northern portions of the Plains by the weekend. Ahead of this cooldown, warmer than normal temperatures will spread from the western/central CONUS toward the East late next week. Record highs can be expected Wed-Thu in particular across California/Desert Southwest/Great Basin. Temperatures in the 60s and 70s (15 to 25 degrees above average) are likely over the Northern/Central Plains to the Upper Midwest Wed-Sat. Elsewhere, heavy rainfall is possible across Florida (particularly southern and eastern Florida) as moisture interacts with easterly post-frontal flow through the weekend, north of Eta and any possible additional tropical development. Tate Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, 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/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml