Prognostic Meteorological Discussion
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FXUS21 KWNC 261937
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 26 2016

SYNOPSIS: A COLD FRONT IS EXPECTED TO MOVE OFF THE GULF AND ATLANTIC COASTS
EARLY IN THE OUTLOOK PERIOD. BROAD LOW PRESSURE AT THE SURFACE AND ALOFT,
ASSOCIATED WITH THE COLD FRONT, IS FORECAST TO LINGER OVER THE OHIO
VALLEY/MID-ATLANTIC REGION BEFORE FINALLY LIFTING OUT TO THE NORTH OVER THE
WEEKEND. ANOTHER COLD FRONT IS PREDICTED TO MOVE ACROSS THE WESTERN AND INTO
THE CENTRAL CONTIGUOUS U.S. DURING THIS SAME PERIOD, ACCOMPANIED BY THE COLDEST
TEMPERATURES SO FAR THIS SEASON. IN THE ALASKA DOMAIN, SEVERAL FRONTAL SYSTEMS
ARE ANTICIPATED TO AFFECT THE WESTERN PORTION OF THE STATE DURING THE FIRST
HALF OF THE OUTLOOK PERIOD.

HAZARDS

HEAVY RAIN FOR SOUTHWESTERN PORTIONS OF ALASKA, SAT-SUN, OCT 1-2.

HEAVY RAIN FOR PARTS OF SOUTHERN FLORIDA, SAT, OCT 1.

FLOODING IS POSSIBLE IN SOUTHWESTERN AND SOUTH-CENTRAL TEXAS, SEP 29-30.

FLOODING IS LIKELY, IMMINENT, OR OCCURRING IN PARTS OF THE MIDWEST, SEP 29-OCT
1.

SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR THE NORTHERN AND CENTRAL
ROCKIES, AND NORTHERN AND CENTRAL INTERMOUNTAIN REGION, TUE-WED, OCT 4-5.

SEVERE DROUGHT ACROSS PARTS OF THE EASTERN CONUS, MISSOURI RIVER VALLEY, GREAT
PLAINS, NORTHERN ROCKIES, INTERMOUNTAIN WEST, ARIZONA, CALIFORNIA, AND HAWAII.

DETAILED SUMMARY

FOR THURSDAY SEPTEMBER 29 - MONDAY OCTOBER 03: A PRONOUNCED CUT-OFF LOW AT
500-HPA IS FORECAST TO BRING CLOUDY AND COOL CONDITIONS TO AREAS PRIMARILY EAST
OF THE MISSISSIPPI RIVER, AT LEAST INTO SUNDAY, OCT 2. BY THEN, THE CUT-OFF LOW
IS PREDICTED TO WEAKEN AND LIFT NORTHWARD INTO SOUTHERN QUEBEC. AT THE SURFACE,
A COLD FRONT IS EXPECTED TO PUSH OFF THE ATLANTIC AND GULF COASTS EARLY IN THE
PERIOD, THOUGH ASSOCIATED LOW PRESSURE (AND ATTENDANT CLOUDINESS) OVER THE OHIO
VALLEY AND MID-ATLANTIC IS PREDICTED TO LINGER ACROSS THIS REGION FOR SEVERAL
MORE DAYS. THE COLD FRONT IS FORECAST TO GET AS FAR SOUTH AS SOUTHERN FLORIDA
BEFORE STALLING, ENHANCING THE CHANCES FOR HEAVY RAIN (ABOUT 1.5 INCHES) IN
THAT AREA ON OCT 1.



FLOODING IS POSSIBLE IN SOUTHWESTERN AND SOUTH-CENTRAL TEXAS, SEP 29-30.
FLOODING IS LIKELY, IMMINENT, OR OCCURRING IN PARTS OF THE MIDWEST, SEP 29-OCT
1. THIS IS PRIMARILY DUE TO BOTH ANTECEDENT AND CURRENTLY FALLING PRECIPITATION.



A CYCLONIC SYSTEM IS PREDICTED TO BRING HEAVY RAIN (2 INCHES OR GREATER) TO
SOUTHWESTERN ALASKA ON OCT 1-2. THE DETERMINISTIC 0Z ECMWF AND 6Z GFS RUNS
FORECAST IN EXCESS OF 4 INCHES DURING THIS PERIOD ACROSS THE VICINITY OF THE
EASTERN ALASKA PENINSULA.

FOR TUESDAY OCTOBER 04 - MONDAY OCTOBER 10: THERE IS A SLIGHT (20 PERCENT)
CHANCE OF MUCH BELOW-NORMAL TEMPERATURES ACROSS NORTHERN AND CENTRAL PORTIONS
OF BOTH THE INTERMOUNTAIN REGION AND ROCKIES ON OCT 4-5, IN ASSOCIATION WITH A
STRONG 500-HPA TROUGH. AT THE HIGHEST ELEVATIONS, TEMPERATURES ARE EXPECTED TO
BE COLD ENOUGH TO SUPPORT SNOW.



ACCORDING TO THE LATEST U.S. DROUGHT MONITOR (USDM) VALID ON SEPTEMBER 20, THE
COVERAGE OF SEVERE OR GREATER DROUGHT (FOR THE CONUS) INCREASED VERY SLIGHTLY
FROM 7.72 TO 7.76 PERCENT DURING THE PAST WEEK.  LESS THAN 1 PERCENT OF THE
HAWAIIAN ISLANDS IS DESIGNATED WITH SEVERE DROUGHT.

FORECASTER: ANTHONY ARTUSA

$$




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