Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Tue Jul 12 2022 Valid 12Z Fri Jul 15 2022 - 12Z Tue Jul 19 2022 ...Uncertain excessive rainfall threat for the central Gulf Coast states... ...Guidance Evaluation/Predictability Assessment... Guidance overall offers a decently similar pattern evolution through medium range time scales over the CONUS and a composite model/ensemble/NBM solution seems to provide a good forecast basis. This includes for upper trough energies breaking inland into the Pacific Northwest through the period as well as for an upper trough over the East to be reinforced some late week into the weekend as a shortwave trough digs to the lee of a building/hot west-central U.S. upper ridge. A noteable exception with high uncertainty remains along the central Gulf Coast where some upper level energy may be left behind this week where a col may exist aloft, but the evolution has become increasingly in question. Some guidance (most notably earlier runs of the ECMWF and UKMET) want to blossom this into a fairly well defined tropical low, and NHC is monitoring in their outlook. However, there is significant uncertainty where this may focus coastal impact from Louisiana to the Florida Panhandle. Recent GFS, CMC and ICON models and now the 00 UTC ECMWF are less enthusiastic with system developmenmt, but do show more organized ejecting pieces of energy inland across the Southeast/FL. The 00 UTC UKMET still has the low. WPC QPF still focuses activity on the central Gulf coast considering continuity and collaborated NHC system preferences, but did trend QPF amounts downward. Please refer to the latest tropical weather outlooks from NHC for the latest information on this feature. ...Overview and Weather/Hazards Highlights... A hot upper high/ridge will settle westward into the Four Corners to support above normal temperatures across much of the West, but also with widespread heat to persist downstream across the central U.S. as ridging/heights build over the region. In this pattern, modest monsoonal moisture flow across the Southwest into the Great Basin/Rockies under the upper ridge may offer daily chances for showers with some locally heavier downpours with slowed cell motions. Meanwhile, a series of uncertain impulses will round the top of the ridge to periodically focus strong convection locally over the north-central Plains/Upper Midwest, but rains may prove more progressive in nature. Upper trough positions will sandwich the upper ridge, both into the Pacific Northwest where rainfall chances are limited and also the East where fronts will focus some rain and thunderstorms. Moisture will pool from the eastern Mid-Atlantic to the Southeast and Gulf Coast states. Possible sub-tropical/tropical interaction over the northern the Gulf of Mexico may support heavy rain potential into the central Gulf Coast and vicinity as slow-moving and repeat cells with very heavy downpours lead to local runoff issues. A "slight" risk area was issued on the experimental WPC medium range Excessive Rainfall Outlook through mid-late week. Models offer potential for a disturbance or tropical low, although there is significant uncertainty in this per NHC. 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