Prognostic Meteorological Discussion
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000
FXUS02 KWBC 241528
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1128 AM EDT SUN MAY 24 2015

VALID 12Z WED MAY 27 2015 - 12Z SUN MAY 31 2015

...OVERVIEW...

SUMMER-LIKE CONDITIONS WILL PREVAIL ACROSS THE EASTERN PORTION OF
THE NATION BENEATH A DEEP-LAYERED RIDGE ANCHORING ACROSS THE
SOUTHEAST MOST OF THIS MEDIUM RANGE PERIOD -- WEDNESDAY THRU NEXT
SUNDAY. SPLIT-FLOW PATTERN IN THE EASTERN PACIFIC DOWNSTREAM FROM
A VERY BLOCKY/AMPLIFIED ALASKA UPPER PATTERN SHOULD DIRECT THE
MAJORITY OF THE SENSIBLE WEATHER AND PRECIPITATION TOWARDS THE
PACIFIC NORTHWEST AND NORTHERN ROCKIES.


...MODEL PREFERENCES/UNCERTAINTY ASSESSMENT...

CONTINUED THE THINKING FROM THE OVERNIGHT SHIFT WITH A PREFERENCE
FOR THE 00Z ECMWF/ECENS MEAN AND NAEFS MEAN. GFS/GEFS ARE NOT TO
BE RULED OUT BUT TREND A BIT QUICKER THAN THE ECMWF-LED
CONSENSUS... WHICH TYPICALLY HANDLES A MORE AMPLIFIED PATTERN
BETTER.

KEY FEATURES OF THE PATTERN REMAIN CONSISTENT -- AMPLIFICATION OF
THE SOUTHEAST RIDGE SHUNTING FRONTS INTO THE ST LAWRENCE VALLEY
AND NEW ENGLAND...  SPLIT-FLOW PATTERN IN THE NE PACIFIC ALLOWS
ENERGY TO PUSH THROUGH SW CANADA AND WA/OR INTO THE INTERIOR...
AND ROTATING NORTHERN STREAM ENERGY AROUND/THROUGH HUDSON BAY.
THIS LAST PIECE WILL HAVE THE MOST INFLUENCE ON TEMPERATURES BY
NEXT WEEKEND IN THE GREAT LAKES/NORTHEAST. FOR NOW... HAVE STAYED
AWAY FROM THE STRONGER GFS SOLUTIONS GIVEN THE OVERALL WEAKER
ENSEMBLE MEMBERS.


...SENSIBLE WEATHER HIGHLIGHTS...

WARM/HOT AND MORE HUMID IN THE EAST COMPARED TO THE CURRENT
WEEKEND... WITH HIT-N-MISS AFTERNOON AND EVENING AIRMASS POP-UP
SHOWERS/THUNDERSTORM ACTIVITY. OVERNIGHT TEMPS MAY BE CLOSE TO
RECORD `HIGH MIN` VALUES. THE MORE ORGANIZED AREAS OF
PRECIPITATION WILL FOLLOW THE WEST THROUGH NORTHWEST FLANKS OF THE
MID-LEVEL RIDGE --- INCLUDING THE SOUTH CENTRAL PLAINS...
OZARKS... MID-MS & WESTERN OHIO VALLEYS AND EASTERN LAKES/NORTHERN
NEW ENGLAND --- WHERE THE MID-CONTINENT FRONT HAS A PATHWAY TO
MIGRATE IN NORTHEASTWARD FASHION TOWARDS THE ST LAWRENCE VALLEY
AND NORTHERN NEW ENGLAND.

CONVECTION SHOULD BE ON THE INCREASE ACROSS THE OKANAGAN REGION OF
BC/WA... THE NORTHERN DIVIDE... AND ADJACENT NORTHERN HIGH PLAINS
THIS MEDIUM RANGE PERIOD AS MID-LEVEL ENERGY MIGRATES
SOUTHEASTWARD FROM THE MOUNTAINS OF SOUTHWEST CANADA AND SOUTHERN
ALASKA PANHANDLE.

ALONG THE WEST COAST THE SPLIT-FLOW PATTERN WILL PROVIDE A GRADUAL
WARMING/DRYING TREND ACROSS THE SOUTHWEST DESERTS AND INTERIOR
CALIFORNIA. AN AMPLIFYING SURFACE RIDGE OVER THE GULF OF ALASKA
WILL PRODUCE AN ONSHORE NORTHWESTERLY FLOW ACROSS THE PACIFIC
NORTHWEST.


FRACASSO/VOJTESAK

$$




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