THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


EXTENDED FORECAST DISCUSSION




EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
109 AM EDT MON SEP 01 2014

VALID 12Z THU SEP 04 2014 - 12Z MON SEP 08 2014

...OVERVIEW AND GUIDANCE PREFERENCES...

UPPER PATTERN SHOULD FEATURE RIDGING IN THE NORTHEAST PACIFIC AND
NORTH-CENTRAL ATLANTIC WITH A PROGRESSIVE UPPER LOW TRACKING
THROUGH NORTHERN CANADA. RIDGING SHOULD BUILD BRIEFLY INTO THE
NORTHEAST/EASTERN GREAT LAKES/MID-ATLANTIC BY THE END OF THE WEEK
BEFORE THE ENERGETIC NORTHERN STREAM ACROSS CANADA DIPS DOWN ONCE
AGAIN INTO THE GREAT LAKES. NE PAC RIDGING WILL SUPPORT A SPLIT
FLOW THAT SHOULD LINGER TROUGHING ALONG 120W. MAIN STICKING POINT
IN THE MODELS CONTINUES TO BE TIMING THE LARGER-SCALE FEATURES.
THE 18Z GFS AND 12Z ECMWF CLUSTERED NEAR THE 12Z ECENS MEAN WHILE
THE 18Z GEFS MEAN APPEARED TO BE A QUICK OUTLIER WITH THE FLOW
ALONG THE US/CANADIAN BORDER. BY THIS COMING WEEKEND... THE GFS
BEGAN TO OUTPACE THE ECMWF/ECENS MEAN. THE OVERALL TREND HAS BEEN
A BIT SLOWER WITH THE FRONTAL PROGRESSION THROUGH THE NORTHEAST SO
OPTED TO LEAN TOWARD THE ECMWF/ECENS MEAN BY SUN/D6 AND THEN JUST
THE EC MEAN FOR MON/D7 MOSTLY DUE TO THE DIFFERENCES OVER AND JUST
UPSTREAM FROM THE PAC NW /ECMWF APPEARS WAY OVERDONE WITH ITS
APPROACHING DEEP UPPER LOW/.


...SENSIBLE WEATHER HIGHLIGHTS...

MAIN PLAYER WILL BE THE FRONTAL BOUNDARY INITIALLY IN THE CENTRAL
PLAINS AND UPPER MIDWEST THU/D4. MILDER TEMPERATURES AHEAD OF THE
COLD FRONT... ABOUT +5 TO +15F... WILL BE REPLACED BY COOLER
TEMPERATURES OF SIMILAR DEPARTURES BUT CONCENTRATED IN THE CENTRAL
PLAINS DUE TO CLOUDY/SHOWERY CONDITIONS POST-FROPA. THE
NORTHEASTERN QUARTER OF THE CONUS WILL FALL BACK TO MORE TYPICAL
SEPTEMBER TEMPERATURES BY SUN-MON NEXT WEEK. PRECIPITATION WILL
ACCOMPANY THE COLD FRONT BUT ALSO SHOULD FALL OVER THE
SOUTHEAST/FLORIDA AND S TX DUE TO SOME ENHANCED TROPICAL MOISTURE.
DEFLECTING UPPER RIDGING OVER INTERIOR TEXAS WILL GRADUALLY GIVE
WAY TO MORE PRECIPITATION BY THE END OF THE PERIOD... NOT TO
MENTION AZ/NM WITH A RENEWED PUSH OF MOISTURE FROM OLD MEXICO.


FRACASSO





Last Updated: 109 AM EDT MON SEP 01 2014