Prognostic Meteorological Discussion
Issued by NWS

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FXUS21 KWNC 021915
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 02 2014

SYNOPSIS: AN ELONGATED COLD FRONT IS PREDICTED TO STRETCH FROM THE UPPER GREAT
LAKES TO THE SOUTHERN PLAINS AT THE BEGINNING OF THE PERIOD AND MOVE EASTWARD
OVER THE NEXT 3-7 DAYS. SURFACE HIGH PRESSURE IS EXPECTED TO BUILD ACROSS MUCH
OF THE EASTERN TWO THIRDS OF THE CONTIGUOUS U.S. BEHIND THE FRONT WHILE SURFACE
LOW PRESSURE DEVELOPS OVER THE GREAT PLAINS BY MONDAY. MONSOONAL FLOW ACROSS
THE SOUTHWESTERN LOWER 48 STATES IS EXPECTED TO BRING WET WEATHER TO PARTS OF
THE AREA DURING THE FIRST HALF OF THE PERIOD. A SURFACE LOW IS ANTICIPATED TO
TRACK ALONG THE SOUTH COAST OF ALASKA, BRINGING UNSETTLED WEATHER TO THE AREA.

HAZARDS

HEAVY RAIN FOR PARTS OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY, AND CENTRAL
PLAINS, MON-TUE, SEP 8-9.

HEAVY RAIN FOR PARTS OF EASTERN NEW MEXICO, FRI-SAT, SEP 5-6.

HEAVY RAIN FOR PARTS OF ARIZONA, SUN-MON, SEP 7-8.

HEAVY RAIN FOR PARTS OF THE EASTERN PORTION OF THE SOUTH COAST OF ALASKA AND
THE ALASKAN PANHANDLE, FRI-SAT, SEP 5-6.

SEVERE DROUGHT FOR THE CENTRAL AND SOUTHERN GREAT PLAINS, SOUTHWEST, SOUTHERN
GEORGIA, PACIFIC NORTHWEST, GREAT BASIN, AND CALIFORNIA.

DETAILED SUMMARY

FOR FRIDAY SEPTEMBER 05 - TUESDAY SEPTEMBER 09: MOIST MONSOONAL FLOW OVER THE
SOUTHWESTERN CONUS IS EXPECTED TO LEAD TO HEAVY RAINFALL (1-2 INCHES IN A
24-HOUR PERIOD) FOR PARTS OF EASTERN NEW MEXICO FRIDAY TO SATURDAY AND ARIZONA
SUNDAY TO MONDAY. HEAVY RAIN MAY LEAD TO LOCALIZED FLASH FLOODING IN THESE
AREAS. INTERESTS INCLUDING THOSE ENGAGING IN OUTDOOR ACTIVITIES SHOULD CLOSELY
MONITOR UPDATED FORECASTS AT WWW.WEATHER.GOV.



SURFACE LOW PRESSURE IS ANTICIPATED TO DEVELOP ACROSS THE GREAT PLAINS BY
MONDAY. THE GREATEST CHANCE FOR HEAVY RAIN IS OVER PARTS OF THE UPPER AND
MIDDLE MISSISSIPPI VALLEY, AND CENTRAL PLAINS MONDAY TO TUESDAY. SOME AREAS MAY
RECEIVE 2 INCHES OR GREATER OF RAINFALL IN A 24-HOUR PERIOD, AS WELL AS
LOCALIZED RIVER FLOODING IN AREAS RECENTLY EXPERIENCING MODERATE FLOOD LEVELS
OR GREATER (SUCH AS IOWA).



A COLD FRONT MOVING ACROSS THE EASTERN CONUS IS EXPECTED TO LEAD TO SHOWERS AND
THUNDERSTORMS FOR PARTS OF THE MID-ATLANTIC THIS WEEKEND, BUT MODEL UNCERTAINTY
PRECLUDES THE SPECIFICATION OF A HAZARD SHAPE AT THE CURRENT TIME.

FOR WEDNESDAY SEPTEMBER 10 - TUESDAY SEPTEMBER 16: A BROADLY CYCLONIC FLOW
PATTERN IS FORECAST OVER THE NORTHERN CONUS WHILE A SUB-TROPICAL RIDGE IS
ANTICIPATED ALONG THE GULF COAST. LATE IN THE PERIOD, THE GFS INDICATES THE
POSSIBILITY OF A TROPICAL SYSTEM MOVING INTO THE GULF OF MEXICO/BAY OF
CAMPECHE. MODEL UNCERTAINTY PREVENTS THE PLACEMENT OF HAZARD AREAS AT THIS
TIME.



THE MOST RECENT U.S. DROUGHT MONITOR, RELEASED ON AUGUST 28, INDICATES THE
PERCENTAGE OF CONUS IN SEVERE TO EXCEPTIONAL DROUGHT DECREASING VERY SLIGHTLY
TO 21.55 PERCENT.

FORECASTER: MELISSA OU

$$



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