Prognostic Meteorological Discussion
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FXUS02 KWBC 291600
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1200 PM EDT SUN MAY 29 2016

VALID 12Z WED JUN 01 2016 - 12Z SUN JUN 05 2016

THE MEDIUM RANGE FORECAST PHILOSOPHY REMAINS UNCHANGED AND THE
FLOW PATTERN  RESHUFFLES ALONG 30N LATITUDE---WITH A MID-PERIOD
`PROGRESSIVE AND WET` MID-LATITUDE TROUGH/SURFACE FRONT MIGRATION
BETWEEN 40N AND 50N LATITUDE.

PREFERRED A MODEL BLEND THAT UTILIZES MORE WEIGHT TOWARDS THE
DETERMINISTIC GFS/ECMWF/UKMET (29/00Z CYCLE) UNTIL 3/00Z-3/12Z
(MID-POINT DAY 5)---BEFORE PARING AWAY FROM THE DETERMINISTIC
GUIDANCE BY THE END OF DAY 6---TO A 70/30 ECENS/GEFS MEAN
DISTRIBUTION.

THE 29/00Z DETERMINISTIC GFS/ECMWF WERE DECENT PIECES OF FORECAST
GUIDANCE THROUGH DAY 6...BUT REMAIN `DIFFERENT` WITH RESPECT TO
MID-LEVEL ENERGY MIGRATION AND MID-LEVEL TROUGH EVOLUTION EXITING
THE SOUTHERN HIGH PLAINS BETWEEN DAY 4 AND DAY 6 ACROSS OKLAHOMA
AND NORTH TEXAS. THE MID-LEVEL SYSTEM WILL SHEAR MOISTURE
NORTHEASTWARD ALONG THE MID-LATITUDE FRONT --- AND PRESS
SOUTHEASTWARD...AS THE ANTICYCLONE ADVANCES SLOWLY EASTWARD TO THE
DIVIDE.

THE CONCEPTUAL MEDIUM RANGE FORECAST---CARRIES TWO `NEW` CLOSED
MID-LEVEL LOWS ---FORMING AROUND 30N. ONE INVOF THE WESTERN GULF
COAST/NORTHEAST MEXICO AND THE OTHER...WEST OF SOUTHERN CALIFORNIA
--- WITH THE FLOW PATTERN ALONG THE US/CANADA BORDER ADJUSTING TO
A WAVELENGTH THAT SHARPENS AND DIGS ---ALONG AND JUST EAST OF 100W
LONGITUDE --- IN RESPONSE TO A VERTICALLY-STACKED ANTICYCLONE THAT
ANCHORS ACROSS THE GREAT BASIN AND `SPILLS OVER` INTO NORTHERN AND
WEST CENTRAL HIGH PLAINS (WEST OF 100W LONGITUDE).

IF A MORE CANADIAN DETERMINISTIC APPROACH WERE TO BE
FOLLOWED---THEN THREE CLOSED LOWS WOULD FORM BY DAY 7---THE THIRD
TRACKING NORTHWARD FROM THE CARIBBEAN (ALONG 80W LONGITUDE). OF
NOTE---THIS IS WHERE THE UPPER-LEVEL LOW---THAT SPAWNED `TD
02/BONNIE`---HAS REMAINED IN PLACE. AND IS ANTICIPATED TO SLOWLY
MEANDER NORTHWARD UNTIL THE DAY4/5 TIME FRAME.

WEST OF THE DIVIDE...
SUBTLE DIFFERENCES BETWEEN THE DETERMINISTIC RUNS (GFS/ECMWF)
ALONG 130W SHOULD EVENTUALLY RESOLVE THEMSELVES ONCE THE UPPER
ANTICYCLONE SETTLES IN ACROSS THE GREAT BASIN AND BEGINS TO STEER
THE CLOSED 500 MB LOW ON A MORE NORTH-TO-NORTH-NORTHWEST
TRAJECTORY. THE MODELS DO NOT NECESSARILY SHOW THIS YET --- BUT
WITH THE ANTICYCLONE LOOKING MORE AND MORE LIKE SOMETHING WE WOULD
SEE IN JULY --- THE CUTOFF WILL HAVE NO WHERE TO GO BUT
NORTHWARD---RATHER THAN HAVE A TRUE EASTWARD TRAJECTORY. HERE
AGAIN... A CANADIAN DETERMINISTIC SOLUTION OFFERS A THIRD
SCENARIO.

VOJTESAK













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