558  
FXUS02 KWBC 281558  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1157 AM EDT THU MAR 28 2019  
 
VALID 12Z SUN MAR 31 2019 - 12Z THU APR 04 2019  
   
..OVERVIEW
 
 
STRONG UPPER RIDGING OVER ALASKA WILL DRIFT NORTHWESTWARD INTO  
NORTHEASTERN RUSSIA NEXT WEEK WILL FAVOR A WESTWARD SHIFT IN  
TROUGHING OVER THE CONUS--INITIALLY OVER THE GREAT LAKES AND  
NORTHEAST SUN-MON THEN BACK TO THE PLAINS/UPPER MIDWEST NEXT  
WED/THU. TROUGHING IN THE NORTHEASTERN PACIFIC WILL CONTINUE TO  
SEND SYSTEMS INTO THE WEST UNDERNEATH THE ALASKAN UPPER HIGH,  
FOCUSED AROUND MON-TUE.  
 
   
..GUIDANCE ASSESSMENT/PREFERENCES
 
 
THE MODELS/ENSEMBLES GENERALLY AGREED ON THE LONGWAVE PATTERN WITH  
DIFFERENCES ON TIMING/STRENGTH OF THE EMBEDDED SYSTEMS. AREAS OF  
CONCERN WERE 1) OVER THE GULF MON/TUE WHERE LOW PRESSURE IS STILL  
FORECAST TO DEVELOP ALONG A SLOWLY MOVING COLD FRONT, BUT  
ENSEMBLES SHOW A LARGE AMOUNT OF SEPARATING IN TIMING/LOCATION OF  
SAID LOW (ECMWF AND ITS ENSEMBLES GENERALLY SLOWER THAN THE  
GFS/UKMET AND GEFS. ENSEMBLE SIGNAL HAS BEEN INCONSISTENT SO AN  
INTERMEDIATE SOLUTION WAS PREFERRED FOR NOW. BY TUE/WED, THE 00Z  
ECMWF/GFS COME INTO BETTER AGREEMENT WITH ESPECIALLY THE ECMWF  
ENSEMBLE MEAN, SO THAT CLUSTER OF SOLUTIONS WAS PREFERRED WHICH  
WAS SLOWER THAN THE 06Z GFS/FV3-GFS, KEEPING IT CLOSER TO THE  
OUTER BANKS BUT JUST OFFSHORE.  
 
IN THE WEST, ANOTHER SYSTEM WILL PUSH THROUGH THE GREAT BASIN  
TUESDAY THEN ONTO THE PLAINS WEDNESDAY. 00Z GFS SEEMED TO RAISE  
HEIGHTS TOO QUICKLY BEHIND THIS SYSTEM GIVEN THE TELECONNECTIONS  
(AND MOST ENSEMBLES) THAT FAVOR AT LEAST SOME TROUGHING TO REMAIN  
JUST EAST OF THE ROCKIES. ENSEMBLE MEANS SHOWED THIS NICELY AND  
WAS THE MAJORITY OF THE PREFERENCE. WITH A SLOWLY WESTWARD MOVING  
TROUGH AXIS, THIS WOULD FAVOR ANY SURFACE LOW DEVELOPMENT TO LIFT  
NORTHEASTWARD THROUGH THE GREAT LAKES AROUND NEXT THURSDAY WITH A  
COOL SHOT OF CANADIAN AIR BEHIND IT.  
 
...WEATHER HIGHLIGHTS/HAZARDS  
 
COOLER TEMPERATURES WILL SPREAD EASTWARD FROM THE PLAINS TO THE  
EAST COAST BEHIND THE EXITING SYSTEM ON SUNDAY WHILE RAINFALL  
EXPANDS ALONG THE CENTRAL/EASTERN GULF COAST INTO NORTHERN FLORIDA  
AND THE SOUTHEAST MON/TUE. RAINFALL COULD BE LOCALLY HEAVY  
DEPENDING ON HOW AND WHERE THE SURFACE LOW (OR LOWS) DEVELOP(S).  
IN THE WEST, FRONTAL SYSTEM WILL BRING RAIN/SNOW TO OREGON  
EASTWARD WITH A MODEST PRECIPITABLE WATER AXIS BACK TO HAWAI'I. PW  
ANOMALIES OF +2 TO +3 WILL SUPPORT SOME LOCALLY HEAVY  
PRECIPITATION BUT PROGRESSIVE MOVEMENT WILL LIMIT THE DURATION. AS  
A NORTHERN STREAM FRONT AND PACIFIC ENERGY INTERACT EAST OF THE  
ROCKIES, ANOTHER AREA OF AT LEAST MODEST PRECIPITATION WILL EXPAND  
ACROSS THE UPPER MIDWEST AND WESTERN GREAT LAKES. THIS MAY  
EXACERBATE ONGOING FLOODING AS RAIN IS EXPECTED FOR MOST AREAS  
SOUTHEAST OF A ~RAPID CITY, SD TO INTERNATIONAL FALLS, MN LINE  
(PER THE CURRENT FORECAST) WITH SOME SNOW TO THE NORTHWEST.  
 
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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