315  
FXUS02 KWBC 140629  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
229 AM EDT THU MAR 14 2019  
 
VALID 12Z SUN MAR 17 2019 - 12Z THU MAR 21 2019  
   
..OVERVIEW
 
 
UPPER RIDGE/TROUGH PATTERN OVER THE WEST/EAST WILL SLOWLY SLIDE  
EASTWARD NEXT WEEK IN A RATHER DRY PATTERN FOR THE CONUS EXCEPT  
FOR FLORIDA. WEAK NORTHERN STREAM MOISTURE-STARVED FRONTS WILL  
SWEEP THROUGH THE EAST EARLY IN THE WEEK WHILE A COLD FRONT STALLS  
NEAR THE FLORIDA KEYS. THIS FRONT WILL BE A FOCUS FOR RAINFALL  
LATER NEXT WEEK THAT MAY BE HEAVY IN PLACES. THE WEST WILL  
INITIALLY BE PROTECTED FROM A COMPLICATED/EVOLVING FRONTAL SYSTEM  
OFFSHORE DUE TO THE UPPER RIDGE, BUT ONLY UNTIL ABOUT WEDNESDAY  
WHEN IT WILL SEND A FRONT INTO CALIFORNIA.  
 
   
..GUIDANCE ASSESSMENT/PREFERENCES
 
 
LARGE SCALE PATTERN REMAINS WELL-FORECAST BUT SMALLER DETAILS  
REMAIN ELUSIVE. TREND IN THE CENTRAL/EASTERN STATES IS A BIT  
FLATTER BY TUE BUT WOULD ONLY MODULATE THE WEAK FRONTAL  
POSITIONING IN THE SOUTHEAST BACK TO THE SOUTHERN/CENTRAL PLAINS.  
STILL EXPECT A WAVE TO FORM ALONG THE FRONT NEAR CUBA BUT THAT  
DEPENDS ON THE STRENGTH OF THE SHORTWAVE EJECTING OUT OF MEXICO  
AND THROUGH THE GULF. BLENDED SOLUTION AMONG THE GFS/ECMWF AND  
THEIR ENSEMBLE MEANS WAS A GOOD STARTING POINT.  
 
FOR THE WEST, ISSUE REMAINS HOW EXACTLY THE EASTERN PACIFIC  
UNFOLDS IN A COMPLICATED/MERIDIONAL PATTERN. ECMWF HAS TRENDED  
QUICKER WHILE THE GFS HAS TRENDED SLOWER, AND EACH PASSED EACH  
OTHER A COUPLE CYCLES AGO. ENSEMBLES FOLLOWED THE LEAD OF EACH  
DETERMINISTIC MODEL SO A BLENDED POSITION (NEAR THE 12Z CANADIAN)  
WAS PREFERRED--MOSTLY IN LINE WITH CONTINUITY.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
FLORIDA WILL SEE THE MOST RAINFALL DURING THE PERIOD, CENTERED  
AROUND TUESDAY. SOUTHERN THIRD TO HALF OF THE PENINSULA WILL SEE  
MORE RAIN THAN THE NORTHERN PORTION. THIS WILL KEEP TEMPERATURES  
SEVERAL DEGREES COOLER THAN AVERAGE THROUGH THE PERIOD. LARGER  
NEGATIVE DEPARTURES WILL CENTER OVER TEXAS, ESPECIALLY NEAR THE  
MEXICAN BORDER. REST OF THE LOWER 48 WILL BE NEARLY  
PRECIPITATION-FREE EXCEPT FOR SOME LIGHT RAIN/SNOW NORTH OF I-40  
NEAR THE WEAK SURFACE FRONTS/UPPER LEVEL SHORTWAVES. CALIFORNIA  
WILL SEE RAINFALL SPREAD SLOWLY INLAND STARTING LATE TUE INTO WED  
AND INCREASING IN COVERAGE ON THURSDAY AS THE UPPER LOW MOVES  
INLAND. AREAS BETWEEN SAN FRANCISCO TO SAN DIEGO EASTWARD WILL  
LIKELY SEE AT LEAST MEASURABLE RAIN AND HIGHER ELEVATION (SIERRA  
BUT ALSO SAN GABRIEL/BERNADINO/JACINTO PEAKS) SNOWFALL. THIS WILL  
ALSO MOVE INTO NEVADA/UTAH ON THURSDAY.  
 
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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