590  
FXUS02 KWBC 031600  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1159 AM EDT FRI NOV 03 2017  
 
VALID 12Z MON NOV 06 2017 - 12Z FRI NOV 10 2017  
   
..PATTERN OVERVIEW/GUIDANCE/UNCERTAINTY ASSESSMENT/PREFERENCES
 
 
A LONGWAVE PATTERN WILL AFFECT THE UNITED STATES THE NEXT WEEK  
WHILE A RIDGE WILL BE CENTERED ACROSS MEXICO/GULF OF MEXICO. THIS  
RIDGE WILL HOVER NEAR THE SOUTHEAST AND SOUTHERN PLAINS AS  
DISTURBANCES PROGRESS ACROSS THE NORTHERN AND CENTRAL PORTIONS OF  
THE STATES. ONCE THE FORECAST REACHES DAY 5/WEDNESDAY, MODELS  
BEGIN TO DIVERGE ON CERTAIN DETAILS ACROSS THE COUNTRY. ONE OF  
THE BIGGEST ISSUES IS HOW MODELS ARE HANDLING THE POWERFUL  
NORTHEASTERN PACIFIC SYSTEM UPSTREAM NEAR THE GULF OF ALASKA. HOW  
THIS SYSTEM EVOLVES WILL HAVE AN IMPACT ON HOW THINGS EVOLVE  
ACROSS THE CENTRAL AND EASTERN U.S. BY DAY 6 AND 7.  
 
ON DAY 3/MONDAY...A LARGE CYCLONE THAT WILL LIFT INTO EASTERN  
CANADA WILL SWEEP A STRONG COLD FRONT OVER THE  
NORTHEAST/MID-ATLANTIC WITH IT EXITING THE COAST BY THE END OF DAY  
3. ON THE WEST COAST...A SHORTWAVE WILL DIG ACROSS THE PACIFIC  
NORTHWEST AND CONTINUE AN EASTERN TREK TOWARD THE PLAINS OVER THE  
NEXT FEW DAYS. THE EVOLUTION OF THIS SHORTWAVE IS UNCERTAIN AND  
COMPLICATED. BOTH THE 00Z AND 06Z GFS IS MORE PROGRESSIVE WITH  
THIS FEATURE WHILE THE 00Z ECMWF IS SLOWER WITH IT...THIS IS DUE  
TO THE GFS DROPPING THE UPPER LEVEL LOW FROM THE GULF OF ALASKA  
FASTER AND CLOSER TO THE PACIFIC NORTHWEST REGION VERSUS THE ECMWF  
ON DAY 5. THE 00Z UKMET ALSO CONTINUED LEANING TOWARD THE SLOWER  
SOLUTION AS THE ECMWF WHILE THE 00Z CMC LEANED TOWARD THE FASTER  
SOLUTION. BY DAY 6/7...THE 00Z ECMWF AND 06Z GFS DISAGREE ON THE  
PROGRESSION OF A SHORTWAVE EJECTING OUT OF THE SOUTHWEST WHICH  
WILL MOVE TOWARD THE SOUTHERN PLAINS/SOUTHEAST AS THEY ARE WITH  
HOW FAST THE UPPER LEVEL LOW MOVES ACROSS THE PACIFIC  
NORTHWEST--WITH THE GFS CONSISTENTLY BEING THE FASTER AND MORE  
PROGRESSIVE SOLUTION WHILE THE ECMWF IS CONSISTENT WITH THE SLOWER  
SOLUTION.  
 
WITH ALL OF THIS IN MIND...THE USE OF OPERATIONAL MODELS HAD A  
SIGNIFICANT DROP OFF IN THE BLEND BY DAY 5 AND BEYOND. ON DAYS 3  
AND 4...THE 06Z GFS/00Z ECMWF HAD EQUAL FOOTING ALONG WITH A SMALL  
FRACTION OF THEIR ENSEMBLE MEMBERS. BY DAYS 5-7, COMBINED BOTH  
THE 00Z NAEFS ENSEMBLE MEAN AND 06Z GEFS MEAN WITH SOME 00Z ECENS.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
A BAND OF RAIN ALONG THE COLD FRONT STRETCHING ACROSS THE EASTERN  
AND CENTRAL U.S. WILL CONTINUE TO MOVE THROUGH THE NORTHEAST AND  
MID-ATLANTIC ON DAYS 3 AND 4. SOME RAINFALL COULD LINGER ALONG  
THE CAROLINAS AS THE FRONT SLOWS IN THIS AREA. FARTHER  
WEST...EXPECT A COLD AND WET PERIOD ESPECIALLY LATER ON IN THE  
WEEK. HIGHER ELEVATION SNOW IS ALSO EXPECTED ACROSS MUCH OF THE  
WESTERN U.S.  
 
EXPECT UNSEASONABLY WARM TEMPERATURES ACROSS THE EASTERN AND  
SOUTHERN U.S. ON DAYS 3 AND 4 AHEAD OF THE INCOMING COLD FRONT.  
AS THE COLD FRONT PASSES, COOLER AND MORE SEASONABLE TEMPERATURES  
WILL SETTLE BEHIND IT. SOME OF THE COLDEST TEMPERATURES OF THE  
SEASON WILL BE FELT IN THE NORTHERN PLAINS ON DAY 3. BY THE LATER  
HALF OF THE WEEK...MOST OF THE COUNTRY WILL BE COOLER WITH SOME  
SLIGHTLY ABOVE NORMAL TEMPERATURES ACROSS THE SOUTHWEST AND  
CENTRAL GREAT BASIN.  
 
REINHART  
 

 
 
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