392   
FXUS21 KWNC 231859  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT OCTOBER 23 2024  
  
SYNOPSIS: MID-LEVEL LOW (HIGH) PRESSURE OVER THE WESTERN (EASTERN) HALF OF THE   
CONTIGUOUS U.S. (CONUS) IS PREDICTED FOR MUCH OF THE WEEK-2 PERIOD. THIS   
PATTERN FAVORS A SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE MIDDLE AND   
LOWER MISSISSIPPI VALLEY, AND CENTRAL AND SOUTHERN PLAINS, WITH THE POTENTIAL   
FOR HIGH WINDS ACROSS THE CENTRAL CONUS DURING THE FIRST HALF OF THE PERIOD.   
AMPLIFIED MID-LEVEL LOW PRESSURE OVER THE BERING SEA AND ALASKA MAINLAND IS   
PREDICTED TO ACCOMPANY SURFACE LOWS OVER THE BERING SEA AND GULF OF ALASKA THAT   
COULD LEAD TO HIGH WINDS TO COASTAL PORTIONS OF SOUTHERN ALASKA INCLUDING   
SOUTHWESTERN ALASKA AND THE ALEUTIANS. HEAVY PRECIPITATION IS ALSO EXPECTED   
ALONG THE SOUTH-CENTRAL AND SOUTHEASTERN COASTS OF ALASKA, FROM PRINCE WILLIAM   
SOUND TO KETCHIKAN.  
  
HAZARDS  
  
SLIGHT RISK OF HEAVY PRECIPITATION IN ALASKA FROM PRINCE WILLIAM SOUND EASTWARD   
AND SOUTHWARD TO KETCHIKAN, THU-MON, OCT 31-NOV 4.  
  
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE MIDDLE AND LOWER   
MISSISSIPPI VALLEY AND CENTRAL AND SOUTHERN PLAINS, THU-SAT, OCT 31-NOV 2.  
  
SLIGHT RISK OF HIGH WINDS FROM PORTIONS OF THE CENTRAL CONUS ACROSS THE UPPER   
GREAT LAKES REGION, THU-SUN, OCT 31-NOV 3.  
  
SLIGHT RISK OF HIGH WINDS FOR COASTAL SOUTHERN ALASKA INCLUDING SOUTHWESTERN   
ALASKA, AND THE ALEUTIANS, THU-SUN, OCT 31-NOV 3.  
  
DETAILED SUMMARY  
  
FOR SATURDAY OCTOBER 26 - WEDNESDAY OCTOBER 30:   
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
  
FOR THURSDAY OCTOBER 31 - WEDNESDAY NOVEMBER 06: THERE IS GOOD AGREEMENT AMONG   
MULTIPLE MODEL ENSEMBLE MEANS INDICATING MID-LEVEL TROUGHING (RIDGING) OVER THE   
WESTERN (EASTERN) HALF OF THE CONUS DURING MUCH OF WEEK-2. NORTHERN STREAM   
FEATURES ARE EXPECTED TO OUTRUN SOUTHERN STREAM FEATURES LATE IN WEEK-2,   
LEAVING BEHIND A RESIDUAL TROUGH OVER THE SOUTHWEST. FOR MOST OF THE PERIOD,   
HOWEVER, THE TROUGH-RIDGE PATTERN IS CONDUCIVE TO LEE-SIDE CYCLOGENESIS AND   
FRONTAL ACTIVITY OVER THE CENTRAL CONUS WHICH COULD SUPPORT ENHANCED WIND   
SPEEDS AND PRECIPITATION DURING THE FIRST HALF OF WEEK-2. A SLIGHT RISK OF   
HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS PARTS OF THE MIDDLE AND LOWER   
MISSISSIPPI VALLEY, AND THE CENTRAL AND SOUTHERN PLAINS, OCT 31-NOV 2,   
ASSOCIATED WITH THE INCREASED POTENTIAL FOR THUNDERSTORMS WHICH MAY PRODUCE   
LOCALIZED HEAVY PRECIPITATION. THE RISK AREA HIGHLIGHTED IS PRIMARILY BASED ON   
A COMPROMISE BETWEEN THE DRIER GEFS AND CMCE PROBABILISTIC EXTREMES TOOL (PET)   
AND THE SIGNIFICANTLY WETTER ECENS PET. THE ECENS PET INDICATES AT LEAST A 30%   
CHANCE OF 3-DAY RAINFALL TOTALS EXCEEDING ONE INCH IN THE DESIGNATED TIME   
PERIOD, AND EXCEEDING THE HISTORICAL 85TH PERCENTILE.  
  
THE AFOREMENTIONED FRONTAL SYSTEM MAY ALSO SUPPORT ENHANCED WIND SPEEDS.   
ADDITIONALLY, SOME MODELS INDICATE A SIGNIFICANT SURFACE LOW TRACKING ACROSS   
THE NORTHERN PLAINS, WHICH WOULD BE MORE SUPPORTIVE OF HIGH WINDS ACROSS THE   
CENTRAL CONUS. THEREFORE, THE AREA OF A SLIGHT RISK OF HIGH WINDS IS INDICATED   
FOR A BROAD AREA WHICH INCLUDES THE GREAT PLAINS AS FAR SOUTH AS CENTRAL   
OKLAHOMA, THE UPPER AND MIDDLE MISSISSIPPI VALLEY, AND THE UPPER GREAT LAKES   
REGION, OCT 31-NOV 3. THE GEFS, ECENS, AND CANADIAN PETS ARE IN GOOD AGREEMENT   
INDICATING WINDS SPEEDS OF AT LEAST 20-25 MPH ACROSS THE HIGHLIGHTED RISK AREA.  
  
MULTIPLE ENSEMBLE MEANS INDICATE SIGNIFICANT MID-LEVEL TROUGHING OVER THE   
BERING SEA AND WESTERN ALASKA, AND ASSOCIATED SURFACE LOW PRESSURE SYSTEMS   
WHICH ARE PREDICTED TO BRING AN ELEVATED RISK OF HIGH WINDS TO THE EXTENSIVE   
SOUTHERN COAST OF ALASKA (FROM THE ALEUTIANS TO THE PANHANDLE). THE PETS SHOW   
AT LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE AND 40 MPH.   
HIGH WINDS AND WAVE ACTION COULD ENHANCE THE LIKELIHOOD FOR EROSION ACROSS   
SOUTHWESTERN COASTAL ALASKA.  TODAY’S MODEL RUNS HAVE GENERALLY BACKED OFF ON   
THE ANOMALOUS COLD THAT WAS PREDICTED YESTERDAY OVER ALASKA, CONFINING IT TO   
THE WESTERN COAST. FINALLY, THERE IS A SLIGHT RISK OF HEAVY PRECIPITATION   
DEPICTED FOR THE SOUTH-CENTRAL AND SOUTHEASTERN COASTS OF ALASKA, FROM ABOUT   
PRINCE WILLIAM SOUND TO KETCHIKAN, OCT 31-NOV 4.  THE ECENS PET IS MORE ROBUST   
THAN THE GEFS PET, WITH CHANCES EXCEEDING 30% OVER MUCH OF THIS REGION FOR 2-3   
INCHES OF PRECIPITATION, WITH LOCALLY HEAVIER AMOUNTS POSSIBLE.  
  
FORECASTER: ANTHONY ARTUSA   
  
  
 
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