US HAZARDS ASSESSMENT
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300
PM EDT SEPTEMBER 15 2008
SYNOPSIS: AFTER A VERY ACTIVE PATTERN
ACROSS THE US DURING THE PAST FEW WEEKS, THE ASSESSMENT PERIOD WILL FEATURE
RELATIVELY TRANQUIL CONDITIONS ACROSS MUCH OF THE COUNTRY AS HIGH PRESSURE WILL
DOMINATE MUCH OF THE PERIOD. HEAVY RAINFALL ASSOCIATED WITH RECENT TROPICAL
CYCLONE ACTIVITY WILL CONTINUE THE THREAT FOR FLOODING STRETCHING FROM THE
SOUTH-CENTRAL PLAINS ACROSS THE MIDDLE MISSISSIPPI VALLEY TO THE SOUTHWESTERN
GREAT LAKES. A RIDGE OF HIGH PRESSURE ACROSS THE NORTH-CENTRAL US WILL RESULT
IN ABOVE-AVERAGE TEMPERATURES ACROSS THE NORTHERN PLAINS, UPPER-MISSISSIPPI
VALLEY AND WESTERN GREAT LAKES.
HAZARDS - ONGOING RIVER
FLOODING FROM THE SOUTH-CENTRAL PLAINS TO THE SOUTHWESTERN GREAT LAKES
THROUGHOUT THE PERIOD.
- RIVER FLOODING FOR SOUTHWESTERN TEXAS SEP 18-19.
- LINGERING FLOODING FOR EAST-CENTRAL FLORIDA SEP 18-20.
- RIVER FLOODING FOR SOUTHERN ARKANSAS SEP 18-19.
- RIVER FLOODING FOR SOUTHWESTERN LOUISIANA SEP 18-20.
- MUCH ABOVE AVERAGE TEMPERATURES FOR THE NORTHERN PLAINS AND
UPPER-MISSISSIPPI VALLEY SEP 18-21
- SEVERE DROUGHT WILL CONTINUE FOR PARTS OF CALIFORNIA, OREGON, NEVADA,
WYOMING, NORTH DAKOTA, MONTANA, TEXAS, OKLAHOMA, KANSAS, COLORADO, SOUTH
CAROLINA, GEORGIA, TENNESSEE, AND NORTH CAROLINA
DETAILED SUMMARYFOR THURSDAY SEPTEMBER 18
- SATURDAY SEPTEMBER 20: RECENT VERY HEAVY AND EXTENSIVE RAINFALL
ASSOCIATED WITH TROPICAL SYSTEMS IKE AND LOWELL AND A FRONTAL SYSTEM PRODUCED
LARGE RAINFALL TOTALS ACROSS PORTIONS OF THE CENTRAL US. THE PRECIPITATION
TOTALS DURING THE PAST 7 DAYS RANGED FROM 3-10 INCHES WITH LOCALLY HEAVIER
AMOUNTS OVER A LARGE AREA STRETCHING FROM KANSAS TO SOUTHERN MICHIGAN.
EXTENSIVE FLOODING IS EXPECTED TO CONTINUE WELL INTO THE ASSESSMENT PERIOD FROM
THE SOUTH-CENTRAL PLAINS TO THE SOUTHERN GREAT LAKES. MOREOVER, LINGERING
FLOODING IS EXPECTED TO CONTINUE FOR SECTIONS OF EAST-CENTRAL FLORIDA, SOUTHERN
ARKANSAS, SOUTHWEST LOUISIANA, AND SOUTHWEST TEXAS DUE TO PREVIOUS TROPICAL
SYSTEMS. HIGH PRESSURE WILL PREVAIL OVER MUCH OF THE COUNTRY DURING THE PERIOD
SO FURTHER SUBSTANTIAL RAINFALL IS NOT EXPECTED DURING THE PERIOD AT THIS TIME
SO FLOODING RELIEF EFFORTS WILL NOT BE INHIBITED SIGNIFICANTLY. AN UPPER-LEVEL
RIDGE WILL RESULT IN SUFFICIENTLY HIGH POSITIVE 500-HPA HEIGHT ANOMALIES ACROSS
THE NORTHERN PLAINS EARLY DURING THE PERIOD TO RESULT IN MUCH ABOVE-NORMAL
TEMPERATURES IN THIS REGION. TEMPERATURES IN THIS REGION WILL REACH 12-16
DEGREES ABOVE AVERAGE IN MANY LOCATIONS ESPECIALLY ACROSS THE NORTHERN PLAINS.
THE AREA IS LIKELY TO SLOWLY SHIFT EASTWARD DURING THE PERIOD BUT TEMPERATURES
WILL LIKELY ONLY RANGE 8-12 DEGREES ABOVE AVERAGE.
AN AREA OF DISTURBED WEATHER WILL PERSIST OFF THE SOUTHEAST COAST DURING THE
FORECAST PERIOD AND INTERESTS ALONG THE SOUTHEAST COAST FROM GEORGIA TO NORTH
CAROLINA SHOULD MONITOR FOR STRONG WAVE ACTION AND POTENTIAL BEACH EROSION AND
COASTAL FLOODING. SEVERE DROUGHT WILL REMAIN ACROSS PARTS OF CALIFORNIA, THE
INTER-MOUNTAIN WEST, NORTHERN PLAINS, SOUTH CENTRAL PLAINS AND SOUTHEAST. MOST
AREAS WILL NOT SEE ANY RELIEF DURING THE PERIOD. DUE TO RECENT RAINFALL FROM
TROPICAL SYSTEMS THE SEVERE DROUGHT AREA IN SOUTHERN TEXAS WILL SEE SOME
RELIEF. IN PART ASSOCIATED WITH THE CURRENT PHASE OF THE MADDEN-JULIAN
OSCILLATION (MJO), THE DEEP TROPICAL ATLANTIC SHOULD CONTINUE TO SEE GENERALLY
SUPPRESSED TROPICAL CYCLONE ACTIVITY.
FOR SUNDAY SEPTEMBER 21 -
THURSDAY SEPTEMBER 25: THIS FORECAST PERIOD WILL SEE THE CONTINUATION OF
GENERAL HIGH PRESSURE ACROSS MUCH OF THE COUNTRY. FLOODING WILL REMAIN A
CONCERN DURING THE PERIOD ACROSS A LARGE REGION OF THE CENTRAL US ESPECIALLY
THE UPPER-MISSISSIPPI VALLEY. CONTINUED GENERALLY QUIET CONDITIONS WILL LIMIT
ANY DROUGHT RELIEF FOR CURRENT SEVERE DROUGHT AREAS. DURING THIS FORECAST
PERIOD, THE ENHANCED PHASE OF THE MJO IS EXPECTED TO CONTINUE SHIFTING EASTWARD
AND THE LIKELIHOOD OF TROPICAL DEVELOPMENT ACROSS THE EASTERN PACIFIC AND FAR
WESTERN GULF OF MEXICO AND CARIBBEAN INCREASES.
FOR FRIDAY SEPTEMBER 26 - MONDAY
SEPTEMBER 29: THE ENHANCED PHASE OF THE MJO IS EXPECTED TO CONTINUE
SHIFTING EASTWARD DURING THIS FORECAST PERIOD AND THE LIKELIHOOD OF TROPICAL
DEVELOPMENT ACROSS THE DEEP TROPICAL ATLANTIC INCREASES. THE THREAT FOR
DEVELOPMENT IS EXPECTED TO REMAIN ELEVATED ACROSS THE FAR EASTERN PACIFIC, GULF
OF MEXICO AND CARIBBEAN DURING THE PERIOD. THE LACK OF PREDICTABILITY AT THIS
TIME RANGE PRECLUDES THE FORECAST OF SPECIFIC HAZARDS ACROSS THE CONUS.
FORECASTER: JON GOTTSCHALCK
$$