851  
FXUS02 KWBC 130633  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
233 AM EDT WED MAR 13 2019  
 
VALID 12Z SAT MAR 16 2019 - 12Z WED MAR 20 2019  
   
..OVERVIEW
 
 
UPPER RIDGING OVER WESTERN CANADA WILL SLOWLY NUDGE EASTWARD NEXT  
WEEK WITH ITS AXIS DOWN THE SPINE OF THE ROCKIES. THIS FAVORS  
BROAD TROUGHING DOWNSTREAM OVER THE CENTRAL/EASTERN STATES AND A  
SLOWLY APPROACHING TROUGH OFF THE WEST COAST AS WELL AS A SOUTHERN  
STREAM TROUGH MOVING ACROSS MEXICO MONDAY AND THROUGH THE GULF  
NEXT TUE/WED.  
 
   
..GUIDANCE ASSESSMENT/PREFERENCES
 
 
THE 18Z GFS/FV3-GFS AND 12Z ECMWF OFFERED REASONABLE CLUSTERING  
NEAR THEIR ENSEMBLE MEANS SUCH THAT A BLENDED SOLUTION WAS  
UTILIZED FOR THE FIRST FEW DAYS OF THE PERIOD (SAT-MON). BY NEXT  
TUE/WED, DIFFERENCES IN THE UPSTREAM SHORTWAVE SPEED/TRACK EXPAND  
AS THEY MOVE ACROSS THE NORTHERN TIER AND/OR GET LEFT BEHIND UNDER  
THE EXPANDING RIDGE (OR UPPER HIGH) OVER ALBERTA/SASKATCHEWAN. IN  
THE PACIFIC, TREND HAS BEEN TOWARD A DEEPER/SLOWER TROUGH OR UPPER  
LOW THAT MAY AIM TOWARD SOUTHERN CALIFORNIA (OR EVEN BAJA  
CALIFORNIA NORTE) AND OPTED TO WEIGHT THE ECMWF ENSEMBLE MEAN MORE  
THAN THE GEFS MEAN AS IT WAS DEEPER, BUT NOT AS DEEP AS THE  
DETERMINISTIC RUN.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
A COLD FRONT WILL SETTLE NEAR THE FLORIDA KEYS AS A WAVY  
STATIONARY FRONT LATE THIS WEEKEND, PROVIDING A FOCUS FOR RAINFALL  
THROUGH THE PERIOD. THE COMBINATION OF THIS FRONT AND ONE OR MORE  
SOUTHERN STREAM SHORTWAVES ALOFT MAY PRODUCE PERIODS OF LOCALLY  
MODERATE OR HEAVY RAINFALL OVER THE FLORIDA PENINSULA. EXTREME  
SOUTHERN TEXAS MAY SEE SOME ENHANCED RAINFALL WITH THE ENERGETIC  
FLOW ALOFT AS WELL. THE REST OF THE EAST WILL SEE A DRIER PERIOD  
EXCEPT FOR SOME AREAS OF LAKE ENHANCED SNOW AS WEAK FRONTS ROTATE  
THROUGH THE LAKES. THE WEST SHOULD BE MOSTLY DRY UNTIL MOISTURE  
REACHES THE WEST COAST AROUND NEXT TUE AND ESPECIALLY WED, FOCUSED  
FROM NORCAL NORTHWARD WEST OF I-5.  
 
THE NORTH-CENTRAL AND SOUTHERN PLAINS MAY SEE THE MOST PERSISTENT  
COLD ANOMALIES WITH SOME LOCATIONS AT LEAST 15-20F BELOW NORMAL  
FOR HIGHS THROUGH THE WEEKEND. THE WARMING TREND OVER/NEAR THE  
WEST COAST STATES SHOULD BRING READINGS 5-10F ABOVE NORMAL BY  
SUN-TUE THAT WILL SHIFT INTO IDAHO NEXT WED. THE EAST WILL  
GENERALLY SEE COOLER THAN NORMAL TEMPERATURES THROUGH THE PERIOD  
DUE TO NORTHWESTERLY FLOW.  
 
FRACASSO  
 
ADDITIONAL 3-7 DAY HAZARDS INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE 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  
 

 
 
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