Prognostic Meteorological Discussion
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FXUS21 KWNC 311822
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 31 2015

SYNOPSIS: A COLD FRONT IS PREDICTED TO MOVE SOUTHWARD AND EASTWARD ACROSS THE
LOWER 48 STATES, ORIGINALLY STRETCHING FROM THE NORTHERN PLAINS TO NORTHERN
CALIFORNIA AT THE BEGINNING OF THE PERIOD, TO THE MISSISSIPPI VALLEY AND
SOUTHERN PLAINS BY NEXT MONDAY. SURFACE HIGH PRESSURE IS EXPECTED TO BUILD
ACROSS MOST OF THE COUNTRY, EXCLUDING THIS FRONT. A SURFACE LOW IS ANTICIPATED
TO DEVELOP ALONG THE SOUTH COAST OF ALASKA, POTENTIALLY BRINGING UNSETTLED
WEATHER TO PARTS OF THE SOUTH COAST.

HAZARDS

HEAVY RAIN FOR PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY, SAT,
SEP 5.

SEVERE DROUGHT FOR PARTS OF THE WESTERN THIRD OF THE CONUS, SOUTHERN GREAT
PLAINS, LOWER MISSISSIPPI VALLEY, SOUTHEAST, AND HAWAII.

SLIGHT CHANCE OF MUCH ABOVE NORMAL TEMPERATURES ACROSS EASTERN AND SOUTHERN
TEXAS, TUE, SEP 8.

DETAILED SUMMARY

FOR THURSDAY SEPTEMBER 03 - MONDAY SEPTEMBER 07: A COLD FRONT, ORIGINALLY
STRETCHING FROM THE NORTHERN PLAINS TO NORTHERN CALIFORNIA AT THE BEGINNING OF
THE PERIOD, IS PREDICTED TO TRAVERSE THE CONUS, REACHING THE MISSISSIPPI VALLEY
AND SOUTHERN PLAINS BY NEXT MONDAY. PASSAGE OF THIS COLD FRONT MAY BRING HEAVY
RAIN TO PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY NEXT
SATURDAY. RAINFALL TOTALS MAY REACH 1.5 INCHES OR GREATER IN A 24-HOUR PERIOD
IN THIS AREA.



A SURFACE LOW IS FORECAST TO DEVELOP OVER THE SOUTH COAST OF ALASKA FROM FRIDAY
UNTIL SUNDAY, POTENTIALLY BRINGING HEAVY RAIN TO CENTRAL PARTS OF THE SOUTH
COAST, MAINLY OVER KODIAK ISLAND, THE KENAI PENINSULA, AND PRINCE WILLIAM
SOUND. THIS AREA MAY RECEIVE 1.5 INCHES OF RAINFALL OR GREATER IN A 24-HOUR
PERIOD. BECAUSE OF THE SMALL AREA AND POTENTIAL FOR RAIN AMOUNTS TO NOT REACH
THE HEAVY RAINFALL CRITERIA, A SPECIFIC AREA IS NOT HIGHLIGHTED AT THIS TIME.



AS OF 1PM EST, A TROPICAL DISTURBANCE CURRENTLY IN THE EASTERN PACIFIC HAS A
90% CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE IN THE NEXT 5 DAYS. THIS STORM
MAY APPROACH BAJA CALIFORNIA, BRINGING MOISTURE AND RESULTANT LOCALIZED HEAVY
RAIN TO PARTS OF THE SOUTHWEST BY THE END OF WEEK INTO THE WEEKEND. THERE IS
TOO MUCH UNCERTAINTY REGARDING THIS FEATURE TO DETERMINE ANY SPECIFIC LOCATIONS
OF ASSOCIATED HEAVY RAINFALL AT THIS TIME. UPDATED FORECASTS REGARDING THE
STORM TRACK ARE AVAILABLE AT THE NATIONAL HURRICANE CENTER`S WEBSITE AT
WWW.NHC.NOAA.GOV.



PARTS OF WESTERN FLORIDA MAY EXPERIENCE LOCALIZED RIVER FLOODING AT THE
BEGINNING OF THE PERIOD, ASSOCIATED WITH THE REMNANTS OF TROPICAL STORM ERIKA.

FOR TUESDAY SEPTEMBER 08 - MONDAY SEPTEMBER 14: AN AMPLIFIED UPPER-LEVEL RIDGE
IS ANTICIPATED TO DEVELOP OVER SOUTH-CENTRAL CONUS AT THE BEGINNING OF THE
WEEK-2 PERIOD. THIS PATTERN FAVORS A SLIGHT CHANCE OF MUCH ABOVE NORMAL MAXIMUM
TEMPERATURES FOR EASTERN PARTS OF TEXAS. SOME AREAS MAY REACH 95 DEGREES F OR
GREATER.



SURFACE LOWS OVER THE ROCKIES MAY LEAD TO LOCALIZED AREAS OF FREEZING
TEMPERATURES ACROSS PARTS OF THE NORTHERN AND CENTRAL ROCKIES AT THE BEGINNING
OF WEEK-2. SURFACE HIGH PRESSURE IS EXPECTED TO BUILD FROM CENTRAL CANADA
SOUTHWARD INTO THE NORTHERN AND CENTRAL GREAT PLAINS ON TUESDAY, SEPTEMBER 8,
POTENTIALLY LEADING TO COOLER THAN NORMAL TEMPERATURES IN THIS AREA. THE GEFS
REFORECAST TOOL INDICATES A POTENTIAL FOR THESE AREAS REACHING TEMPERATURES
LESS THAN OR EQUAL TO THE 15TH PERCENTILE COMPARED TO CLIMATOLOGY. HOWEVER,
TEMPERATURES ARE NOT EXPECTED TO REACH FREEZING LEVELS AT THIS TIME. THIS
SURFACE HIGH IS PREDICTED TO SHIFT EASTWARD TO THE UPPER AND MIDDLE MISSISSIPPI
VALLEY ON WEDNESDAY, SEPTEMBER 9, SHIFTING THE FOCUS OF COLDER TEMPERATURES TO
THE UPPER AND MIDDLE MISSISSIPPI VALLEY, AND CENTRAL PLAINS. THE ONLY AREA THAT
IS ALSO ANTICIPATED TO HAVE TEMPERATURES REACHING 40 DEGREES F IS IN THE UPPER
PENINSULA OF MICHIGAN. DUE TO THE SMALL SPATIAL REGION EXPECTED TO HAVE
TEMPERATURES CONDUCIVE TO FROST AND THE SHORT-LIVED NATURE OF THIS PATTERN, A
MUCH BELOW NORMAL TEMPERATURE AREA IS NOT IDENTIFIED AT THIS TIME.



ACCORDING TO THE U.S. DROUGHT MONITOR MAP, VALID ON AUGUST 25, THE COVERAGE OF
SEVERE TO EXCEPTIONAL DROUGHT (D2 TO D4) DECREASED FROM 18.21 TO 18.07 PERCENT
ACROSS THE CONTIGUOUS U.S. SINCE THE PREVIOUS WEEK.

FORECASTER: MELISSA OU

$$



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