683  
FXUS02 KWBC 070627  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
127 AM EST THU FEB 07 2019  
 
VALID 12Z SUN FEB 10 2019 - 12Z THU FEB 14 2019  
 
...OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT AND  
PREFERENCES...  
 
PACIFIC FLOW REMAINS FRAUGHT WITH UNCERTAINTY SURROUNDING A  
STUBBORN UPPER HIGH NEAR THE GULF OF ALASKA. TROUGHING WILL  
GENERALLY STAY FOCUSED NEAR/ALONG THE WEST COAST OF THE LOWER 48,  
REINFORCED EITHER FROM THE NORTH (ON THE EAST SIDE OF THE UPPER  
RIDGE) OR FROM THE WEST (UNDERNEATH THE UPPER RIDGE). AN UPPER  
HIGH OVER THE FLORIDA STRAITS WILL WEAKEN AND SPLIT E-W FROM  
MEXICO TO THE GREAT ANTILLES, OPENING UP BROAD TROUGHING INTO THE  
EAST. HOWEVER, HOW THIS UNFOLDS IS QUITE UNCERTAIN AS EVIDENCED BY  
THE NOTABLE TIMING/TRACK DIFFERENCES AMONG THE GUIDANCE FROM AS  
EARLY AS 48 HRS NEAR ALASKA. MULTI-DAY TREND SUPPORTS SOMETHING  
ALONG THE LINE OF THE 12Z ECMWF ENSEMBLE MEAN AND 12Z ECMWF RATHER  
THAN THE 12Z/18Z GFS/GEFS THOUGH THE 12Z/18Z FV3-GFS RUNS WERE AT  
LEAST HALFWAY TOWARD THE ECMWF FROM THE OPERATIONAL GFS RUNS. IN  
ORDER TO MAINTAIN CONTINUITY IN THE FACE OF RECALCITRANT ENSEMBLE  
MEMBERS, OPTED TO RELY MOSTLY ON THE 12Z ECMWF ENSEMBLE MEAN FOR  
THE BASIS OF THE FORECAST. THIS WILL TAKE A SYSTEM NORTHEASTWARD  
TOWARD THE GREAT LAKES/NORTHEAST LATE MONDAY INTO WEDNESDAY AS A  
COUPLE MORE SYSTEMS SINK THROUGH THE WEST.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
MUCH BELOW AVERAGE TEMPERATURES WILL REMAIN ANCHORED OVER THE HIGH  
PLAINS THROUGHOUT THE MEDIUM RANGE PERIOD (MT/ND/SD). THE REST OF  
THE WEST IS FORECAST TO SEE BELOW AVERAGE TEMPERATURES DUE TO THE  
PERSISTENT TROUGHING AND EPISODIC COOLER SURGES OF CANADIAN AIR.  
THIS MAY RESULT IN SOME RECORD COLD TEMPERATURES FOR COASTAL WA/OR  
AND NORTHERN CALIFORNIA SUN/MON. SLIGHTLY BELOW AVERAGE  
TEMPERATURES WILL BLEED INTO THE UPPER MIDWEST AND THEN GREAT  
LAKES BEHIND THE MIDWEEK SYSTEM. A SURGE OF ABOVE AVERAGE  
TEMPERATURES WILL PRECEDE THE COLD FRONT ESPECIALLY TUESDAY.  
 
LATE THIS WEEKEND AND INTO EARLY NEXT WEEK ANOTHER ROUND OF  
POTENTIALLY HEAVY PRECIPITATION WILL SPREAD INTO THE LOWER TO  
MID-MISSISSIPPI AND TENNESSEE VALLEYS AS MOISTURE SURGES NORTHWARD  
ATOP A WARM FRONT ALONG THE GULF COAST. AS A LOW PRESSURE SYSTEM  
STRENGTHENS INTO THE MIDWEST ON TUESDAY, PRECIPITATION IS EXPECTED  
TO PUSH THROUGH THE OHIO VALLEY AND INTO THE  
MID-ATLANTIC/NORTHEAST. WITH TEMPERATURES NEAR/BELOW FREEZING,  
WINTRY PRECIPITATION WILL BE POSSIBLE ON THE NORTHWEST/NORTH SIDE  
OF THE LOW AND WELL AHEAD OF THE WARM FRONT -- GENERALLY NORTH OF  
40N. THROUGH THE WEST, LOW PRESSURE SYSTEMS WILL BRING SEVERAL  
ROUNDS OF LIGHT TO MODERATE VALLEY RAIN/MOUNTAIN SNOW TO THE  
REGION, ESPECIALLY FROM CENTRAL CA/SIERRA NORTHWARD TO OREGON AND  
SOUTHERN WASHINGTON.  
 
FRACASSO  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION AND WINTER WEATHER OUTLOOK  
PROBABILITIES ARE FOUND AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page