386
FXUS21 KWNC 281834
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT September 28 2026

SYNOPSIS: Surface high pressure extending from southern Canada into the
northeastern contiguous U.S. (CONUS) may bring the first frost to parts of the
Northeast, southern Great Lakes region, and Ohio and Middle Mississippi Valleys
at the beginning of week-2 South of this surface high, a cold front may bring
heavy precipitation to parts of the Gulf Coast states, Tennessee and  Lower
Mississippi Valleys, and southern Mid-Atlantic. Periods of heavy rainfall is
possible for the Florida Peninsula throughout week-2. Tropical disturbances
southwest of Baja California and the Gulf of America could enhance moisture
enhancing precipitation totals as well. A series of low pressure systems with
enhanced onshore flow results in a slight risk of heavy precipitation and high
winds for southcentral and southeastern Alaska.

HAZARDS

Slight risk of much below normal temperatures across parts of the Northeast,
southern Great Lakes region, and Ohio and Middle Mississippi Valleys, Tue-Wed,
Oct 6-7.

Slight risk of heavy precipitation for parts of the Gulf Coast states,
Tennessee and  Lower Mississippi Valleys, and southern Mid-Atlantic, Tue-Thu,
Oct 6-8.

Slight risk of heavy precipitation for the Florida Peninsula, Tue-Mon, Oct 6-12.

Slight risk of heavy precipitation for parts of southcentral and southeastern
Alaska, Tue-Mon, Oct 6-12.

Slight risk of high winds for coastal parts of southcentral and southeastern
Alaska, Tue-Mon, Oct 6-12.



DETAILED SUMMARY

FOR THURSDAY OCTOBER 01 - MONDAY OCTOBER 05:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY OCTOBER 06 - MONDAY OCTOBER 12: The GEFS and ECENS are in good
agreement today on an amplifying 500-hPa ridging (troughing) over western
(eastern) North America during early October. Surface high pressure is
anticipated over southern Canada and parts of the eastern CONUS at the
beginning of the period, which could bring anomalously cool temperatures to
parts of the northeastern CONUS. A slight risk of  much below normal
temperatures is posted across parts of the Northeast, southern Great Lakes
region, and Ohio and Middle Mississippi Valleys, Oct 6-7, where some areas in
the Northeast may experience their first frost and cold temperatures may impact
susceptible vegetation in the eastern Corn Belt. Multiple Probabilistic
Extremes Tools (PETs) indicate at least a 20% chance of minimum temperatures
falling to the lowest 15th percentile climatologically and below 40 deg F.



A cold front along the southern portion of the aforementioned surface high
pressure over the East may bring heavy precipitation to some areas across the
southeastern CONUS. A slight risk of heavy precipitation is designated for
parts of the Gulf Coast states, Tennessee and  Lower Mississippi Valleys, and
southern Mid-Atlantic, Oct 6-8, where the GEFS and ECENS PETs are in good
agreement indicating 3-day precipitation totals exceeding the 85th percentile
and one inch. The ECENS PET shows at least 20% chances of 3-day precipitation
totals exceeding 1.5 inches, although the GEFS counterpart limits these higher
amounts to offshore. Further south, a stationary front is expected to bring
periods of enhanced rainfall to the Florida Peninsula throughout week-2.
Increased chances of tropical disturbances southwest of Baja California and the
Bay of Campeche could support further enhanced moisture to parts of the East,
contributing to enhanced precipitation amounts. The southern extent of the
surface high pressure across the east serves as a contributing factor of
uncertainty in terms of the northern extent of the heaviest precipitation.





A highly amplified 500-hPa trough over the northeast Pacific is likely to
promote a series of low pressure systems that track from the Alaska Peninsula
eastward to the Gulf of Alaska. Based on the enhanced onshore flow associated
with these low pressure systems, and support from the ECENS and GEFS PETs (20%
chance of 3-day precipitation amounts > 85th percentile and 2-3 inches), a
slight risk of heavy precipitation is designated from the Kenai Peninsula to
southeastern Alaska. Recent deterministic models indicate the potential for
daily totals exceeding 2 inches. Since the GEFS, ECENS, and CMCE persist the
deep 500-hPa trough over the North Pacific through early October, the heavy
precipitation hazard is maintained for the entirety of week-2. Although most of
the model ensemble members only depict surface lows of moderate strength
(mostly 970-990 hPa), a slight risk of high winds is maintained based on
pattern recognition and support from the PETs, with the ECENS PET indicating a
greater than 30% chance of wind speeds exceeding the 85th percentile. The high
wind hazard is also valid from Oct 5-11. The GEFS probabilities of exceeding
this threshold is further inland than the ECENS along southeastern Alaska, but
does show at least a 20% chance of some parts of this region having wind speeds
exceeding 40 mph albeit a smaller area than the ECENS. It should be noted that
there is a possibility that high winds could extend to the Alaska Peninsula and
southwestern Alaska, depending on the track and evolution of the remnants of
what is currently Typhoon Surigae currently located south of Japan. This will
be monitored in the upcoming days.





Anticipated above-normal temperatures and dry conditions across the West may
enhance wildfire risk, especially across the Cascades eastward to the Northern
Rockies. Some of these areas are already experiencing active wildfires.



In the Central and Eastern Pacific, the tropics remain very active with two
hurricanes (Nolo and Polo), remnant low Odalys, Tropical Storm Rachel, and a
broad area of low pressure currently well east-southeast of Hawaii which has a
90 percent (high) chance of tropical development within the next week,
according to the National Hurricane Center as of 2pm EST. Although
environmental conditions appear to be conducive for development of a tropical
depression, the system is predicted to move northeastward away from the
Hawaiian Islands. This is good news for the residents of Hawaii that have
already experienced a memorable hurricane season this year. It remains to be
seen whether or not the evolution of Tropical Storm Rachel results in
significant precipitation into the American Southwest in early October.

FORECASTER: Melissa Ou

$$