Preliminary Forecasts
Issued by NWS
Issued by NWS
286 FXUS02 KWNH 080659 PREEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 158 AM EST Fri Nov 8 2024 Valid 12Z Mon Nov 11 2024 - 12Z Fri Nov 15 2024 ...Hurricane Rafael not likely a threat to the Gulf Coast... ...Overview... The National Hurricane Center continues to issue advisories for Hurricane Rafael in the Gulf of Mexico, but based on the current official forecast track, Rafael should be weakening and moving southward into the Bay of Campeche by Monday and therefore likely not a threat to the U.S. Gulf Coast aside from some tropical moisture across the Southeast. Farther west, a large scale system will bring an episode of rain and high elevation snow to the Pacific Northwest through the Rockies into Monday with this system continuing into the eastern half of the country by mid- late week. Another system should focus additional precipitation over the Northwest by midweek. Expect above normal temperatures over most of the East through about Wednesday while the upper trough crossing the West early next week will bring a couple days of cooler temperatures to the region. ...Guidance/Predictability Assessment... Continue to monitor latest NHC products for additional information on Hurricane Rafael which should weaken by the start of the medium range period as it tracks over the Gulf of Mexico. There remains some uncertainty late weekend/early next week on the exact track as some ensemble members (and still the CMC) bring the center near or over the central Gulf Coast (in a very weakened state), but these solutions are considered outliers. The most recent NHC forecast track continues to show a preference more like the ECMWF/UKMET with a southwestern dive toward the Bay of Campeche and possibly into Mexico as a weak surface low. Despite the spread, at least it is pretty clear that the center of Rafael itself should not impact the U.S., aside from some tropical moisture spreading northward into the Southeast. A weak shortwave into the Midwest on Monday already shows some uncertainty in strength. The CMC tries to close off a low over the Southeast by Tuesday and is an outlier in doing so. Prefer a weaker shortwave that moves through the Northeast as suggested by ensemble mean guidance. Behind this, the next system moves into the West by Monday with quite a bit of uncertainty Tuesday and beyond as it moves East. The ECMWF continues to be slower and a little deeper with this system, while the better consensus (and WPC continuity) is more progressive into the Midwest/Northeast Wednesday and beyond. Prefer a blend towards the GFS, CMC, and ensemble means for this system. Another shortwave enters the Northwest later in the week and WPC prefers a non-GFS blend for this system since the GFS is significantly slower. ...Weather/Hazards Highlights... Some tropical moisture from Rafael may extend northward and focus along a frontal boundary through the Southeast early in the week, but outside of very localized heavy rainfall pockets, limited instability is expected to limit the overall threat. An upper trough with leading surface front focusing an atmospheric river will approach the Pacific Northwest and then move inland by Monday, bringing an episode of focused precipitation to the region. Given anticipated rainfall beginning on Sunday at the end of the short range period, a marginal risk remains in place for the new Day 4/Monday Excessive Rainfall Outlook covering the Pacific Northwest into northern California. Another AR looks to take aim into the Pacific Northwest by later in the Day 5/Tuesday period, and so a marginal risk is also depicted on the ERO that day as well. Precipitation from this system should extend into Wednesday and Thursday as well. Modest snowfall is expected in the higher elevations of the Cascades and into the northern Rockies with these systems. The system affecting the West early in the week will progress eastward and bring some areas of precipitation to the eastern half of the country during at least parts of the Tuesday-Thursday period. Important lower-predictability details still have to be resolved before confidence can increase regarding specifics of where/when the greatest totals will occur. But the low track near the Great Lakes could spread moderate to high winds especially over the waters but possibly for some land areas like Michigan`s Upper Peninsula. While system progression will provide some day-to-day variability, much of the eastern half of the country should see well above normal temperatures into mid-week. Expect the warmest anomalies to be for morning lows, with morning temps 15-20F above normal over the Southeast/Mid-Atlantic early Monday. Broadest coverage of plus 10F or greater highs should be during Monday- Wednesday. The northern and southern thirds of the Plains will also see a period of warmth Monday-Tuesday (and still southern Texas on Wednesday). Corresponding to these relative anomalies, there will be better potential for some record warm lows versus more isolated records for daytime highs. Parts of the Northeast may be near normal at times though with more seasonable normal temperatures returning to much of the East late in the week. The southern Rockies/High Plains will remain chilly to the extent that snow cover lingers, while the upper trough crossing the West early next week will bring a brief period of moderately below normal temperatures. Santorelli 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.phpSchichtel/Hamrick WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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 https://www.wpc.ncep.noaa.gov/#page=ovw $$