Extended Forecast Discussion NWS Weather Prediction Center College Park MD 116 PM EDT Mon May 30 2022 Valid 12Z Thu Jun 02 2022 - 12Z Mon Jun 06 2022 ...Weekend heavy rain threat increasing over southern Florida ahead of a tropical system... ...Model Guidance Evaluation/Preferences... Recent model guidance is in reasonably good agreement for the overall synoptic pattern, with the exception of the 06z GFS being a little farther south with a deep layer cyclone in south-central Canada. There is better agreement with the upper low/trough edging into the West from the Pacific. Notable differences continue to be seen near FL this weekend with the system at least partially due to northeast Pacific Hurricane Agatha's remnants. Models continue to show the potential for low pressure in the Bay of Campeche/Yucatan/northwestern Caribbean to deepen as it approaches FL with a general northeast track. GFS and Canadian model runs continue to be on the fast side of the envelope, with the ECMWF on the slower side. When this typical distribution is seen with any recurving low, a compromise is preferred, though did lean somewhat towards the 00z ECMWF as a precaution late in the period as it starts to interact with a frontal zone. See NHC tropical weather outlooks for more on this system's potential for development. Used a compromise of the deterministic guidance for placement of features/pressures/preferred 500 hPa height pattern/winds early, before using increasing amounts of ensemble mean with time to take into account uncertainty. The remainder of the grids are a more even blend of guidance similar to the 13z National Blend of Models. ...Sensible Weather/Threat Highlights... Rain chances are expected to increase in the Northwest during the latter half of the week given the trough axis near the West Coast and onshore flow. The Southwest should remain dry and hot, with Death Valley expected to meet or exceed 110F high temperatures this weekend into early next week. There is increasing forecast agreement for Hurricane Agatha over the eastern Pacific to move northeastward across southeast Mexico over the next 2-3 days while weakening. Showers and thunderstorms are expected to become more frequent and widespread across southern Florida Friday and Saturday ahead of the remnant disturbance, first with the moisture streaming northeast ahead of the system and then with the surface low. Moisture aloft from the far eastern Pacific and lower level moisture from the Caribbean should lead to heavy rainfall, even if the system's timing is in question. Even in the cyclone's wake, its convergent tail appears to be stuck in the vicinity of South FL & the Keys, keeping the threat of moderate to heavy rainfall in play into early next week. The experimental Day 5 Excessive Rainfall Outlook has a Slight Risk for the Keys and South FL (June 3 12z-June 4 12z), after favorable coordination with the KEY/Key West FL and MFL/Miami FL forecast offices. A cold front moves across the East late this week, with rain and thunderstorms expected in its vicinity. Areas of the eastern Mid-Atlantic could see locally heavy rainfall and an isolated flash flood threat Thursday, with a similar threat across portions of the Carolinas on Friday. Rain and thunderstorms are expected in the vicinity of a front dropping south through the Southeast and Gulf coast before returning northward into TX. These fronts will continue to spark additional rounds of enhanced rainfall across the central U.S. this weekend near its tail with the usual uncertainties in placement. A relatively flat pattern aloft compared to the more amplified short range period should produce lesser temperature anomalies late this week into early next week. Cooler than average spots will be across the central/southern Plains Thursday into Friday with rain cooled air, but should switch to above normal in Texas by about 10F by early next week. Periodic troughing in the northern tier should lead to slightly below average temperatures by 5-10F. The western U.S. could be warmer than normal by 5-10F late in the workweek but cooler temperatures are forecast by the weekend under the troughing influence/as a cold front moves through the area. Warm temperatures across the Southeast Thursday will moderate closer to normal late week behind a cold frontal passage. Roth/Tate 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