551  
FXUS02 KWBC 170659  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
258 AM EDT WED OCT 17 2018  
 
VALID 12Z SAT OCT 20 2018 - 12Z WED OCT 24 2018  
   
..PATTERN OVERVIEW
 
 
TROUGHING IN THE GREAT LAKES THIS WEEKEND WILL BE RELOADED NEXT  
TUE/WED WHILE THE WESTERN RIDGE SLOWLY/STUBBORNLY RELENTS.  
SUBTROPICAL RIDGING OVER FLORIDA WILL SQUASH INTO CUBA AS A WEAK  
UPPER LOW OVER CALIFORNIA DRIFTS THROUGH THE GREAT BASIN. THE  
PATTERN IS RATHER COOL/DRY FOR MUCH OF THE LOWER 48 BESIDES TEXAS  
AND FLORIDA IN THE VICINITY OF A STALLED FRONT THROUGH THE GULF OF  
MEXICO  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
MODELS AND ENSEMBLES CONTINUE TO OFFER GOOD CLUSTERING THROUGH THE  
NEXT 5-6 DAYS WITH EXPECTED TIMING/AMPLITUDE DIFFERENCES BY NEXT  
TUE/WED. A DETERMINISTIC BLEND OF THE GFS/ECMWF/CANADIAN/UKMET  
OFFERED A GOOD STARTING POINT CLOSE TO CONTINUITY FOR SAT-MON AS A  
LEAD AND SECONDARY COLD FRONT PUSH OFF THE EAST COAST AND ANOTHER  
CANADIAN FRONT DIPS INTO THE WESTERN GREAT LAKES. BY NEXT TUE/WED  
AN APPROACHING PACIFIC SYSTEM (OR COUPLE OF SYSTEMS) WILL  
EVENTUALLY BREAK THE RIDGE OVER THE WEST, BUT THE ECMWF ENSEMBLES  
REMAIN QUICKEST TO LOWER HEIGHTS INTO THE PAC NW WHICH IS RATHER  
UNCHARACTERISTIC IN THE LONGER TERM, BUT HAS BEEN NOTED RECENTLY.  
PREFERRED TO STICK CLOSER TO THE SLOWER CLUSTER OF SOLUTIONS  
AROUND THE 18Z GEFS MEAN THAT INCLUDED THE 12Z GFS/ECMWF.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
THE PACIFIC NORTHWEST WILL SEE SEVERAL DAYS OF ABOVE AVERAGE  
TEMPERATURES AND DRY CONDITIONS THROUGH THE WEEKEND. RAIN CHANCES  
WILL INCREASE NEXT WEEK STARTING LATE MONDAY AS THE FIRST COLD  
FRONT APPROACHES THE COAST. WARM ANTECEDENT TEMPERATURES WILL  
PRECLUDE SNOW FROM ALL BUT THE HIGHEST ELEVATIONS, BUT THAT WILL  
CHANGE AS COOLER AIR WORKS ITS WAY EASTWARD. RAIN WILL BECOME  
WIDESPREAD AND MODERATE TO LOCALLY HEAVY BY MIDWEEK NEXT WEEK. THE  
REST OF THE CONUS WILL SEE NEAR TO BELOW AVERAGE TEMPERATURES WITH  
THE CORE OF THE COOLEST AIR FROM TEXAS NORTHEASTWARD TO THE  
NORTHEAST/NEW ENGLAND. EVEN FLORIDA WILL SLOWLY TREND BACK TOWARD  
MORE TYPICAL LATE OCTOBER TEMPERATURES IN THE UPPER 70S (NORTH) TO  
MID 80S (SOUTH).  
 
COASTAL TEXAS HAS THE HIGHEST PROBABILITY OF THE GREATEST AMOUNT  
OF PRECIPITATION EAST OF THE ROCKIES DUE TO AN INITIAL AND THEN  
SUBSEQUENT STATIONARY BOUNDARY THROUGH THE GULF NEXT TO AN  
INVERTED TROUGH. THOUGH MOST OF THIS MAY STAY OFFSHORE, AREAS NEAR  
BROWNSVILLE MAY SEE SEVERAL INCHES OF RAIN OVER THE PERIOD. MUCH  
LESS PRECIPITATION IS EXPECTED ELSEWHERE WITH EACH FRONTAL PASSAGE  
EXCEPT FOR PERHAPS FLORIDA WITH STRONG EASTERLY FLOW.  
COASTAL WA/OR WILL SEE LIGHT-MODERATE RAIN DEVELOP AND EXPAND  
INLAND EARLY NEXT WEEK AS UPPER TROUGHING APPROACHES WITH SEVERAL  
INCHES POSSIBLE ALONG THE IMMEDIATE COAST BY NEXT WEDNESDAY.  
 
FRACASSO  
 
WPC MEDIUM RANGE 500 MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDEXES 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  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page