EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 213 AM EDT WED MAR 19 2014 VALID 12Z SAT MAR 22 2014 - 12Z WED MAR 26 2014 ...AN INTERESTING LATE COLD SEASON WEATHER PATTERN... ...PATTERN OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENTS... ALASKAN RIDGING AS PART OF A DEVELOPING REX BLOCK OVER THE NE PAC THIS WEEKEND INTO NEXT WEEK LEADS TO INCREASED FORECAST SPREAD WITH A DOWNSTREAM WRN US RIDGE AND ERN NOAM MEAN TROUGH COUPLET. THE 12 UTC ECMWF/ECMWF ENSEMBLE MEAN OFFER A LESS PROGRESSIVE/MORE AMPLIFIED SOLUTION THAN THE 12 UTC GFS/GFS ENSEMBLE MEAN...BUT WITH THE 18 UTC GFS/GEFS TRENDING LESS PROGRESSIVE. THE GFS/GEFS TEND TO STRUGGLE WITH AMPLIFIED FLOW WHILE THE ECMWF CAN BE OVER-AMPLIFIED AT TIMES. HOWEVER...GIVEN UPSTREAM BLOCKING PREFER A SOLUTION ON THE LESS PROGRESSIVE/AMPLIFIED SIDE OF THE FULL ENVELOPE OF SOLUTIONS. ACCORDINGLY...WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS ALONG WITH OUR SENSIBLE WEATHER GRIDS HAVE BEEN DERIVED PRIMARILY FROM THE ECMWF AND ESPECIALLY THE ECMWF ENSEMBLE MEAN. ONLY LIMITED INPUT FROM THE 18 UTC GEFS MEAN WAS USED AMID GROWING UNCERTAINTY. THIS BLEND KEEPS REASONABLY GOOD WPC CONTINUITY EVEN THOUGH MOST GUIDANCE HAS LATELY BEEN OFFERING LESS THAN STELLAR RUN TO RUN CONTINUITY BY DAYS 5-7. ...SENSIBLE WEATHER HIGHLIGHTS... THE NEXT COLD SURGE TO AFFECT THE CNTRL-ERN STATES WILL INITIALLY BE LED BY THE SURFACE LOW REACHING THE NORTHEAST EARLY IN THE WEEKEND WITH A TRAILING COLD FRONT EXTENDING SWWD THROUGH THE SRN PLAINS AND EVENTUALLY CROSSING THE SOUTHEAST. A BAND OF SNOW IS POSSIBLE N OF THE SURFACE LOW TRACK WHILE RAINFALL OF VARYING INTENSITY MAY FALL ALONG THE SRN PART OF THE FRONT. UPSTREAM WAVE TRACKING INTO SWRN CANADA WILL BRUSH THE VERY NRN PARTS OF THE WEST WITH LIGHT PRECIP EARLY AND THEN ACTIVITY WILL EXTEND E-SE WITH TIME OVER THE CENTRAL AND ERN US. AT THE VERY LEAST POTENTIAL EXISTS FOR UNUSUALLY FAR SOUTHWARD EXTENT OF SOME WINTRY PCPN FOR LATE MARCH...GIVEN COLD SECTOR TEMPERATURE ANOMALIES OF 10-25F BELOW NORMAL. AT THE VERY MOST THE POTENTIAL EXISTS FOR SRN/NRN STREAM INTERACTION TO FORM A LATE SEASON MIDWEST TO ERN US WINTER STORM DAYS TUE/WED. UPSTREAM ON THE OTHER HAND...RELATIVELY HIGH HGTS ALOFT OVER THE WEST WILL SUPPORT WARM TEMPS OF AT LEAST 5-15 F ABOVE NORMAL. MSTR AHEAD OF THE SYSTEM LURKING OVER THE ERN PAC SHOULD BEGIN TO BRING ORGANIZED PCPN BACK INTO THE CNTRL/NRN WEST COAST TUE THAT WORKS SLOWLY INLAND MIDWEEK. SCHICHTEL