580  
FXUS02 KWBC 250700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
159 AM EST SUN FEB 25 2018  
 
VALID 12Z WED FEB 28 2018 - 12Z SUN MAR 04 2018  
 
...MORE MID-LOWER MS VALLEY/MID-SOUTH HEAVY RAINS AND AN ONGOING  
FLOODING CONCERN...   
..STORMY PATTERN FOR BOTH THE WRN AND ERN U.S
 
 
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
LATEST MODELS AND ENSEMBLES NOW OFFER A WELL CLUSTERED PATTERN  
EVOLUTION FOR THE COMING WEEK. THIS BOLSTERS FORECAST  
CONFIDENCE...ALBEIT WITH SOME CAVEAT AS THE ADVERTISED FLOW  
PATTERN IS TRANSITIONAL AND SORTA WACKY WITH A MULTITUDE OF  
ANOMALOUS/AMPLIFIED SYSTEMS THAT OFFER SOME SIGNIFICANT AND LARGER  
SCALE WEATHER THREATS. NEVERTHELESS...THE WPC MEDIUM RANGE PRODUCT  
SUITE WAS SIMPLY DERIVED FROM A COMPOSITE MODEL AND ENSEMBLE BLEND.  
 
IN THIS SCENARIO...POSITIVE HEIGHT ANOMALIES BUILD FROM THE  
E-CENTRAL PACIFIC OVER ALASKA TO THE ARCTIC OCEAN. A STRONG ENERGY  
CONDUIT DUG SOUTHWARD TO THE LEE OF THE RIDGE LEADS TO DEEP CLOSED  
LOW FORMATION JUST OFF THE PACIFIC NORTHWEST THURSDAY/FRIDAY. THE  
BULK OF HEIGHT FALLS THEN CRASH INLAND ACROSS THE WRN US NEXT  
WEEKEND IN STORMY AND COOLING/WET FLOW AS LEAD HEIGHT RISES BUILD  
A WARMING CENTRAL U.S. RIDGE. AMPLE WRN US ENERGY CRESTS THE  
ROCKIES NEXT SUN TO INDUCE PLAINS SYSTEM GENESIS/RENEWED ACTIVE  
FLOW.  
 
MEANWHILE DOWNSTREAM...A STRONG SRN STREAM MID-UPPER LEVEL TROUGH  
AND WEATHER FOCUS EJECTS FROM THE SWRN US WED AND THE INFUSION OF  
WEAKER NRN STREAM ENERGY LEADS TO CLOSED LOW/TROUGH DEVELOPMENT  
OVER THE E-CENTRAL TO ERN/NERN U.S. THU. THIS SETS THE STAGE FOR  
RETURN MOISTURE TO FUEL WIDESPREAD HEAVY RAINS AND SOME WRAPPING  
NRN TIER SNOWS IN LEAD FLOW AROUND A DEEP SURFACE LOW. THIS  
INCLUDES A THREAT OF MORE MID-MISSISSIPPI VALLEY/MID-SOUTH HEAVY  
RAINS AND AN ONGOING FLOODING CONCERN. SPC IS ALSO MONITORING A  
THREAT OF SEVERE WEATHER. THE ACTIVE SYSTEM IS NUDGED  
SOUTHEASTWARD OFF THE MID-ATLANTIC/NERN U.S. INTO NEXT WEEKEND IN  
RESPONSE TO AN ANOMALOUSLY STRONG/BLOCKY UPPER RIDGE OVER THE HIGH  
LATITUDES OF THE NORTH ATLANTIC/GREENLAND THAT SHIFTS WESTWARD  
INTO ERN CANADA.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
MID-LATE WEEK UPPER TROUGH SETTLING ALONG THE WEST COAST AND  
POSSIBLE EMBEDDED CLOSED LOW NEARING THE PACIFIC NW WILL BRING  
INCREASING POTENTIAL FOR AREAS OF HEAVY RAIN/HIGHER ELEVATION SNOW  
OVER PORTIONS OF THE WEST. EXPECT HIGHEST TOTALS FROM THE  
COASTAL/CASCADE AREAS OF THE PACIFIC NW TO NRN CA AND THE SIERRA  
NEVADA RANGE. ENHANCED PRECIP IS ALSO POSSIBLE ALONG THE REST OF  
THE CA COAST AND INLAND TO THE ROCKIES. ARRIVAL OF UPPER TROUGHING  
WILL LEAD TO A DECREASE IN SNOW LEVELS. AHEAD OF THIS LARGE SCALE  
TROUGH...A STRONG SHORTWAVE EJECTS OVER THE SWRN US MIDWEEK WITH  
SOME RAIN AND HIGHER ELEVATION SNOW.  
 
WIDESPREAD CONVECTION AND POTENTIALLY HEAVY RAINS WILL ONCE AGAIN  
POSE A THREAT ACROSS PORTIONS OF THE MID-LOWER MS VALLEY AND  
MID-SOUTH WITH THE POTENTIAL FOR A WIDESPREAD SWATH OF  
PRECIPITATION ACROSS MUCH OF THE E-CENTRAL AND ERN/NERN US WITH  
SYSTEM DEVELOPMENT AND TRACK. THIS THREAT WOULD BE FUELED FROM  
LATE TUE THROUGH THU NIGHT AS MOIST LOW-LEVEL SOUTHERLY FLOW  
WITHIN A CYCLONE'S WARM CONVEYOR BELT SPREADS AMPLE MOISTURE  
NORTHWARD. FARTHER NORTH LOW PRESSURE TRACKING ACROSS THE  
PLAINS/MIDWEST/GREAT LAKES INTO THU WOULD BRING CHANCES OF  
SNOWFALL TO LOCATIONS NORTH OF THE LOW TRACK. POTENTIAL EXISTS FOR  
HEAVY RAIN TO EXTEND INTO PORTIONS OF THE MID-ATLANTIC OR  
NORTHEAST THU-FRI WITH SNOW POSSIBLE FOR NEW ENGLAND.  
 
SCHICHTEL  
 

 
 
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