661
FXUS21 KWNC 071758
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 07 2023
SYNOPSIS: MID-LEVEL HIGH (LOW) PRESSURE IS FORECAST OVER THE WEST (EAST) DURING
MID-SEPTEMBER. HURRICANE LEE, CURRENTLY LOCATED ACROSS THE CENTRAL ATLANTIC, IS
FORECAST TO TRACK NORTHWESTWARD DURING THE NEXT WEEK. THE MODEL CONSENSUS
DEPICTS LEE REMAINING OFFSHORE OF THE EAST COAST, BUT IT MAY APPROACH NEW
ENGLAND LATER NEXT WEEK WHICH INCREASES THE CHANCE OF HIGH WINDS AND HEAVY
PRECIPITATION FOR THIS REGION. A RAPID ONSET DROUGHT RISK EXISTS FOR THE LOWER
MISSISSIPPI VALLEY DUE TO RECENT/ONGOING HEAT AND INCREASING PRECIPITATION
DEFICITS. ENHANCED ONSHORE FLOW RESULTS IN AN ELEVATED CHANCE OF HEAVY
PRECIPITATION ACROSS SOUTHEASTERN ALASKA.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE NORTHEAST, FRI-MON, SEP
15-18.
SLIGHT RISK OF HIGH WINDS FOR LONG ISLAND AND PARTS OF NEW ENGLAND, FRI-MON,
SEP 15-18.
SLIGHT RISK OF HEAVY PRECIPITATION FOR SOUTHEASTERN ALASKA, FRI-MON, SEP 15-18.
RAPID ONSET DROUGHT RISK FOR PARTS OF THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST.
DETAILED SUMMARY
FOR SUNDAY SEPTEMBER 10 - THURSDAY SEPTEMBER 14:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY SEPTEMBER 15 - THURSDAY SEPTEMBER 21: HURRICANE LEE IS FORECAST TO
BECOME A MAJOR HURRICANE AND TRACK TO THE NORTH OF THE LEEWARD ISLANDS. A KEY
FACTOR IN ITS FUTURE TRACK NEXT WEEK WILL BE AN AMPLIFIED 500-HPA TROUGH OVER
THE EASTERN CONTIGUOUS U.S. (CONUS) AND A COLD FRONT FORECAST TO BE LOCATED
NEAR THE EAST COAST. THIS MID-LEVEL AND SURFACE PATTERN WOULD FAVOR A TRACK
OFFSHORE OF THE EAST COAST, BUT LEE’S FUTURE TRACK SHOULD BE CLOSELY MONITORED.
THE ENSEMBLE SPREAD FROM THE GEFS AND ECMWF BECOMES QUITE LARGE BY THE MIDDLE
PART OF NEXT WEEK AS LEE MOVES TOWARDS THE 70W LONGITUDE OVER THE WESTERN
ATLANTIC. A MAJORITY OF THE 0Z/6Z/12Z GEFS AND 0Z ECMWF ENSEMBLE MEMBERS KEEP
LEE OFFSHORE OF THE EAST COAST, BUT SEVERAL OF THE 0Z ECMWF ENSEMBLE MEMBERS
DEPICT LEE MAKING LANDFALL ACROSS OR NEAR EASTERN NEW ENGLAND ON SEPTEMBER
16/17. A SLIGHT RISK OF HIGH WINDS AND HEAVY PRECIPITATION IS MAINTAINED FOR
PARTS OF THE NORTHEAST FROM SEPTEMBER 15 TO 18, ASSOCIATED WITH THE POTENTIAL
EFFECTS FROM HURRICANE LEE. IF MORE ENSEMBLE MEMBERS SHIFT LEE’S TRACK WESTWARD
CLOSER TO THE EAST COAST, THEN THESE HAZARDS MAY BE UPGRADED TO A MODERATE
RISK. PLEASE REFER TO THE NATIONAL HURRICANE CENTER FOR THE LATEST
UPDATES/FORECASTS ON HURRICANE LEE.
THE RAPID ONSET OF DROUGHT (2-CATEGORY DEGRADATION IN DX LEVELS WITHIN 4 WEEKS
BASED ON THE U.S. DROUGHT MONITOR) RECENTLY OCCURRED ACROSS SOUTHERN
MISSISSIPPI, LOUISIANA, TEXAS, AND SOUTHERN OKLAHOMA. A RAPID ONSET DROUGHT
RISK CONTINUES FROM THE LOWER MISSISSIPPI VALLEY EAST TO PARTS OF ALABAMA,
BASED ON RECENT/ONGOING HEAT AND HIGH EVAPOTRANSPIRATION RATES, 30-DAY
PRECIPITATION DEFICITS, AND THE LACK OF A WET SIGNAL AMONG THE MODEL SOLUTIONS
DURING THE NEXT TWO WEEKS. ALTHOUGH DROUGHT MAY EXPAND ACROSS PARTS OF THE
MIDWEST DURING THE REMAINDER OF SEPTEMBER, THE TRANSITION TOWARDS COOLER
TEMPERATURES MAKES A RAPID ONSET OF DROUGHT LESS LIKELY.
NO TEMPERATURE HAZARDS ARE POSTED TODAY. ALTHOUGH COOLER-THAN-NORMAL
TEMPERATURES ARE FORECAST ACROSS THE MIDWEST AND CORN BELT THROUGH EARLY
WEEK-2, THE RISK OF WIDESPREAD DAMAGING FROST OR FREEZE IS MINIMAL. THE MOST
ANOMALOUS WARMTH IS LIKELY TO BE OVER THE WEST, BUT EXCESSIVE HEAT IS UNLIKELY
AS THE TRANSITION FROM SUMMER TO EARLY FALL BEGINS.
MULTIPLE MODEL ENSEMBLE MEANS DEPICT A LOW PRESSURE SYSTEM OVER THE EASTERN
BERING SEA WITH ASSOCIATED ONSHORE FLOW ACROSS SOUTHEASTERN ALASKA. BASED ON
THE GEFS AND ECMWF PROBABILISTIC TOOLS (MORE THAN A 20 PERCENT CHANCE OF 3-DAY
PRECIPITATION TOTALS EXCEEDING THE 85TH PERCENTILE AND 2 INCHES), A SLIGHT RISK
OF HEAVY PRECIPITATION IS POSTED FOR THAT PART OF ALASKA THROUGH SEPTEMBER 18.
FORECASTER: BRAD PUGH
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