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FXUS10 KWNH 241640
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1240 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 AND GFS


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

PREFERENCE: 00Z ECMWF/00Z 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 00Z GEM THE WEAKEST. THE 12Z NAM/00Z
UKMET AND 00Z 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: 00Z ECMWF
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 00Z GEM/00Z UKMET SOLNS ARE A BIT WEAKER. THE
00Z ECMWF TENDS TO SPLIT THE DIFF WITH THE DEPTH AND ACTUALLY
OVERALL CLUSTERS RATHER WELL WITH THE LATEST GEFS MEAN AND ECENS
MEAN. WILL PREFER THE ECMWF AS A RESULT.


...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: 00Z ECMWF/00Z GEM COMPROMISE
CONFIDENCE: ABOVE AVERAGE THROUGH ABOUT 72 HRS...AVERAGE THEREAFTER

THE FLOW REALLY BEGINS TO AMPLIFY ACROSS THE SOUTHWESTERN CONUS BY
EARLY THIS WEEKEND. THE 12Z NAM AND 12Z GFS ARE AGAIN A BIT
QUICKER IN EJECTING THIS SYSTEM INTO THE FOUR CORNERS REGION ON
SAT AND THEN THE HIGH PLAINS ON SUN. THE 00Z GEM AND 00Z ECMWF ARE
THE SLOWEST WITH THE 00Z UKMET SPLITTING THE DIFF. THE NCEP MODELS
HAVE BEEN PERSISTENTLY A LITTLE FASTER THAN THE NON-NCEP SOLNS AS
COMPARED TO THE LAST FEW MODEL CYCLES. HOWEVER...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
00Z UKMET LIFTS IT THE FARTHEST TO THE NORTH. THE 00Z GEM AND 00Z
ECMWF CLUSTER VERY WELL AND SPLIT THE DIFF. THE 12Z GFS AFTER 72
HRS IS IN BETWEEN THE UKMET AND GEM/ECMWF CAMPS. AT THE SFC...ALL
OF THE MODELS SHOW A VERY STRONG SFC LOW DEVELOPING IN THE LEE OF
THE CNTRL ROCKIES...AND THERE IS RATHER SOLID AGREEMENT WITH ALL
OF THE MODELS WITH THE PLACEMENT OF SFC LOW PRESSURE BY EARLY SUN.
HOWEVER...JUST AFTER THIS PERIOD...THE SAME MODEL SPREAD SEEN
ALOFT BECOMES NOTABLE AT THE SFC AS WELL. BASED ON MODEL
CLUSTERING AND SUPPORT FROM THE LATEST ECENS MEAN...WILL MAINTAIN
CONTINUITY AND CONTINUE TO PREFER A SOLN TWD THE ECMWF/GEM CAMP.


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

PREFERENCE: NON-UKMET CONSENSUS
CONFIDENCE: ABOVE AVERAGE

ALL OF THE MODELS INDICATE A NEW PACIFIC TROUGH GRADUALLY
ADVANCING EAST INTO THE NORTHWEST THIS WEEKEND. ON THE LARGER
SCALE THERE IS VERY GOOD AGREEMENT...BUT THE UKMET IS A LITTLE
STRONGER THAN THE MULTI-MODEL CONSENSUS WITH THE ENERGY EARLY SAT
MOVING INTO WA STATE. THE UKMET ALSO HAS A STRONGER SFC LOW NEAR
VANCOUVER ISLAND EARLY SUN COMPARED TO THE REST OF THE GUIDANCE.
WILL PREFER A NON-UKMET CONSENSUS.


...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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