Prognostic Meteorological Discussion
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FXUS10 KWNH 241851
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM EDT THU APR 24 2014

VALID APR 24/1200 UTC THRU APR 28/0000 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND ECMWF


...SHORTWAVE TROUGH/SURFACE LOW IMPACTING THE MID MS/OH
VALLEYS/MID-ATLANTIC/NORTHEAST...

PREFERENCE: 12Z ECMWF/12Z UKMET COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A SHORTWAVE TROUGH AND DEVELOPING SFC LOW OVER THE CNTRL PLAINS
THIS MORNING WILL ADVANCE PROGRESSIVELY EASTWARD TODAY THROUGH THE
MID MS VLY...AND THEN CROSS THE OH VLY ON FRI. THE MODELS ARE IN
GOOD AGREEMENT IN TAKING THIS ENERGY THROUGH THE NRN MID-ATLANTIC
AND THE NORTHEAST FRI NIGHT AND EARLY SAT WHILE ALSO SUGGESTING IT
WILL WEAKEN AND DAMPEN OUT BY LATE SAT IN FAVOR OF STRONGER
UPSTREAM HEIGHT FALLS APPROACHING. THE 12Z GFS OVERALL IS THE
STRONGEST SOLN...WITH THE 12Z GEM THE WEAKEST. THE 12Z NAM/12Z
UKMET AND 12Z ECMWF SPLIT THE DIFF AND ESSENTIALLY REPRESENT THE
MULTI-MODEL CONSENSUS. WILL MAINTAIN CONTINUITY ATTM...AND
CONTINUE TO PREFER A ECMWF/UKMET COMPROMISE.


...SHORTWAVE TROUGH/CLOSED LOW ADVANCING FROM THE NORTHERN PLAINS
TO THE GREAT LAKES/NORTHEAST...

PREFERENCE: 12Z ECMWF/12Z UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW A SHORTWAVE TROUGH CURRENTLY OVER THE NRN PLAINS
ADVANCING EASTWARD OVER THE NEXT FEW DAYS AND AMPLIFYING SOMEWHAT
AS IT CROSSES THE GRT LAKES REGION. THE ENERGY SHOULD DIG INTO THE
NORTHEAST BY SAT AND CAPTURE THE REMNANTS OF THE INITIAL SHORTWAVE
CROSSING THROUGH MID MS/OH VLYS TODAY AND FRI. THE 12Z NAM AND 12Z
GFS ARE THE STRONGEST SOLNS WITH THE EVOLUTION OF THE CLOSED LOW
THAT DEVELOPS. THE 12Z GEM/12Z UKMET AND 12Z ECMWF ARE WEAKER BUT
NOT SUBSTANTIALLY WEAKER THAN THE NAM/GFS CAMP. OVERALL...THE
STRONGEST MODEL CLUSTERING SUPPORTS A COMPROMISE OF THE ECMWF AND
UKMET AND THERE IS SUFFICIENT AGREEMENT FROM THE LATEST GEFS MEAN
AND ECENS MEAN THAT THIS WILL BE THE PREFERENCE ATTM.


...DEEP UPPER TROUGH/CLOSED LOW CROSSING THE SOUTHWEST/FOUR
CORNERS REGION THIS WEEKEND...
...POWERFUL SURFACE LOW DEVELOPING ACROSS THE MIDDLE OF THE U.S...

PREFERENCE: 12Z GFS/12Z ECMWF COMPROMISE
CONFIDENCE: ABOVE AVERAGE THROUGH ABOUT 72 HRS...AVERAGE THEREAFTER

THE FLOW REALLY BEGINS TO AMPLIFY ACROSS THE SOUTHWESTERN CONUS BY
EARLY THIS WEEKEND AS STRONG SHORTWAVE/JET ENERGY DIGS IN OFF THE
ERN PAC OCEAN AND ACROSS CA. THE 12Z GEM/12Z UKMET AND 12Z ECMWF
HAVE TRENDED JUST A TAD FASTER AND TWD THE ALREADY SLIGHTLY FASTER
12Z NAM/12Z GFS SOLNS IN EJECTING THIS AMPLIFYING TROUGH INTO THE
FOUR CORNERS REGION ON SAT AND THEN THE HIGH PLAINS ON SUN BY
WHICH TIME THE UPPER TROUGH WILL HAVE GONE NEG-TILT AND CLOSED
OFF. OVERALL THERE IS NOT A PARTICULARLY LARGE AMT OF SPREAD ALOFT
WITH THE MASS FIELDS AT LEAST UNTIL ABOUT 72 HRS OUT. AFTER ABOUT
72 HRS...THE 12Z NAM PLACES ITS CLOSED LOW SOUTHEAST OF THE GLOBAL
MODEL CONSENSUS. THE 12Z UKMET LIFTS IT THE FARTHEST TO THE NORTH.
THE 12Z GEM TRENDED FARTHER NORTH...BUT NOT QUITE AS FAR NORTH AS
THE UKMET. THE 12Z ECMWF ALSO TRENDED A LITTLE FARTHER NORTH AND
CLUSTERS WELL NOW WITH THE 12Z GFS. BOTH THE GFS AND ECMWF ARE IN
BETWEEN THE GEM AND NAM SOLNS. GIVEN THE RATHER STRONG MODEL
CLUSTERING AND GOOD SUPPORT FROM THE LATEST GEFS MEAN AND ECENS
MEAN...WILL PREFER A GFS/ECMWF COMPROMISE.


...SHORTWAVE TROUGH EDGING INTO THE NORTHWEST SAT AND SUN...

PREFERENCE: GENERAL MODEL CONSENSUS
CONFIDENCE: ABOVE AVERAGE

ALL OF THE MODELS INDICATE A NEW PACIFIC TROUGH AND AN ASSOCD COLD
FRONT GRADUALLY ADVANCING EAST INTO THE NORTHWEST THIS WEEKEND. ON
THE LARGER SCALE THERE IS VERY GOOD AGREEMENT...AND SO WILL PREFER
A GENERAL MODEL COMPROMISE TO RESOLVE ANY SMALLER SCALE DIFFS.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

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