EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1200 PM EDT MON APR 07 2014

VALID 12Z THU APR 10 2014 - 12Z MON APR 14 2014

...SYNOPSIS...

THE OUTGOING EASTERN U.S. TROUGH WILL LAY DOWN A FRONT IN THE
GULF/CARIBBEAN WHICH WILL LIMIT MOISTURE AVAILABILITY ON DAYS
3-5...AS WE GO THROUGH A PERIOD OF LESSER AMPLIFIED AND MODERATELY
PROGRESSIVE FLOW. THE PATTERN WILL BUCKLE MORE SUBSTANTIALLY ON
DAYS 6/7...SUNDAY AND MONDAY...WHEN A RELATIVELY DRY SOUTHWESTERN
U.S. LOW EMERGES EAST OF THE ROCKIES AND PHASES WITH A BROAD
AMPLIFYING NORTHERN STREAM TROUGH. THIS WILL TAP GULF MOISTURE AND
YIELD A WIDESPREAD RAIN EVENT BEGINNING IN THE PLAINS AND GREAT
LAKES. IN THE NORTHWEST THE GFS/GEFS ARE MORE AGGRESSIVE AT
BREAKING A SYSTEM THROUGH THE RIDGE LATE IN THE PERIOD. THE ECMWF
ENSEMBLE MEAN HAS BEEN THE LEADER IN PREDICTING THE STRENGTH OF
THE RIDGE...AND IT SUGGESTS THE BRUNT OF THE SYSTEM MAY BE
DEFLECTED NORTHWARD.


...MODEL EVALUATION...
GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH THE TRANSITIONAL
PATTERN OVER THE NEXT WEEK. FORECAST CONFIDENCE IS NEAR TO ABOVE
NORMAL...ESPECIALLY EARLY IN THE PERIOD...DUE TO RELATIVELY STABLE
ENSEMBLE SOLUTIONS AND STEADY WPC CONTINUITY.

GFS SOLUTIONS HAVE BEEN CHARACTERISTICALLY ON THE FASTER SIDE OF
THE OPERATIONAL MODELS...BUT THE 06Z GFS WAS SLOWER AND BETTER
ALIGNED WITH THE ECMWF ENSEMBLE MEAN. THE LATEST ECMWF OPERATIONAL
SOLUTION WAS CHARACTERISTICALLY ON THE DEEP SIDE WITH SOME
FEATURES. THIS IS ESPECIALLY TRUE OF THE DEEPER LOW IT WHIP UP
ALONG THE CANADIAN BORDER ON DAY 6...ANCHORING THE DIGGING FULL
LATITUDE TROUGH. GIVEN THIS IS A LARGE SCALE SYSTEM OCCURRING IN
SPRING WE WOULD NOT BE SURPRISED TO SEE MODELS TREND TOWARD A
STRONGER SOLUTION...BUT THE 00Z ECMWF HAD VERY LITTLE SUPPORT FROM
ITS 51 MEMBER ENSEMBLE. WE BEGAN OUR BLEND WITH 50/50 PORTIONS OF
THE 00Z ECMWF AND 06Z GFS ON DAY 3...THEN WEIGHTED OUR SOLUTION
MORE HEAVILY TOWARD THE ECMWF ENSEMBLE MEAN BY DAYS 5-7. BUT WE
MAINTAINED 20-30 PERCENT 00Z ECMWF IN THE BLEND TO REFLECT A
SLIGHTLY STRONGER SYSTEM ALONG THE CANADIAN BORDER...AND ALSO TO
CAPTURE THE ANTICIPATED FRONTAL WAVE THAT WOULD FORM AROUND MO/AR
ON DAY 7 AS THE SOUTHWESTERN LOW EJECTS.


...SENSIBLE WEATHER HIGHLIGHTS...

A NORTHERN STREAM SYSTEM WILL PUSH THROUGH SOUTHERN CANADA WITH
GENERALLY LIGHT PRECIPITATION FOR THE U.S. NORTHERN TIER AND THE
ZONE BETWEEN I-40 AND I-70 ON THU/FRI. PRE-FRONTAL TEMPERATURES
SHOULD WARM ACROSS MUCH OF THE OH VALLEY THEN INTO THE EASTERN
CONUS LATE IN THE WEEK WITH MODEST COOLING BEHIND THE FRONT AS THE
UPPER FLOW BECOMES MORE ZONAL. OUT WEST...PACIFIC TROUGH
ENERGY/HEIGHT FALLS AND AN ASSOCIATED FRONTAL SYSTEM SHOULD WORK
ASHORE INTO CA AND INTO THE SWRN US ALONG WITH LIGHT/SCATTERED
SHOWERS AND SOME COOLING TEMPS. BY SUN-MON/D6-7...NORTHERN STREAM
AND SOUTHERN STREAM ENERGY SHOULD SUPPORT COMBINED BUT ELONGATED
FRONT WITH ORGANIZING SFC LOW PRESSURE THROUGH THE SOUTHERN PLAINS
AND LOWER MS VALLEY. THIS SETS UP THE LIKELIHOOD OF WIDESPREAD
PRECIPITATION...ALTHOUGH PRECIPITABLE WATER VALUES ARE NOT
FORECAST TO REACH MUCH ABOVE THE CLIMATOLOGICAL NORMALS. COOLER
AIR ON THE BACK SIDE OF THIS SYSTEM WILL DROP THE NORTHERN
PLAINS/MIDWEST TO 10-15 DEGREES BELOW AVERAGE.

BURKE