Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10
000
FXUS10 KWNH 241610
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1210 PM EDT WED MAY 24 2017

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

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

12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

CLOSED UPPER LOW OVER THE UPPER MIDWEST DIGGING ACROSS THE
MIDDLE/LOWER MS VALLEY LATER TODAY AND TRACKING TOWARD THE EAST
COAST THU...EXITING NEW ENGLAND FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

OVERALL MODELS CONTINUE TO BE SOLID AGREEMENT WITH THE OVERALL
EVOLUTION/PLACEMENT OF THE MAIN FEATURES BUT GIVEN THIS LARGER
SCALE AGREEMENT AVAILS THE OPPORTUNITY TO DELVE TO LOWER SCALES.
THE MAIN DIFFERENCE NOTED IS THE PLACEMENT/TIMING OF THE FORMER
INNER CORE OF THE UPPER LOW AS IT SWINGS THROUGH THE BASE OF THE
LARGER SCALE TROF THURS AND UP THE EAST COAST FRI.  THE MAIN
DIFFERENCE NOTED WAS THE 00Z UKMET TRENDING MUCH QUICKER OVERALL.
 THE 00Z CMC DEEMPHASIZING THE PIVOT OF THE LARGER SCALE TROF NEAR
LAKE ONTARIO EARLY FRIDAY ALLOWING FOR A FURTHER EAST TROF AND
MORE CONSOLIDATED AS IT SHIFTS UP THE NEW ENGLAND COAST FRI/SAT;
THIS IS A MINOR DETAIL MAINLY NEAR THE LAKE AND UPSTATE
NY/VT...BUT NOT ENOUGH TO PULL IT FROM THE OVERALL PREFERENCE.
THE 12Z NAM TRENDED A BIT CLOSER THAN THE 00Z/06Z SOLUTIONS TOWARD
THE COMMON COMPROMISE AND MATCHES THE ECMWF A BIT CLOSER THAN THE
GFS.   THE 12Z GFS TRENDED A BIT FASTER AND THEREFORE A BIT
EAST/SOUTH OF THE ECMWF SOLUTION PARTICULARLY AFTER THE UPPER LOW
COMBINES FRI/SAT OVER THE NORTHERN MID-ATLANTIC/NEW ENGLAND.
OVERALL A NON-UKMET BLEND IS SUGGESTED AND GIVEN THE OVERALL
AGREEMENT...CONFIDENCE IS SLIGHTLY ABOVE AVERAGE IN THIS BLEND


CLOSED LOW TRACKING ALONG THE WESTERN US/CANADIAN BORDER WITH
DEVELOPING TRAILING TROF ACROSS SNAKE RIVER PLAIN
FRIDAY...NORTHERN ROCKIES SAT AND NORTHERN PLAINS SAT.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE

A CLOSED CYCLONE IS TRANSLATING TO THE LEE SIDE OF THE SOUTHERN
CANADIAN ROCKIES CURRENTLY WITH UPSTREAM SHORTWAVE ENERGY
AMPLIFYING ACROSS WESTERN BC.  MODELS REMAIN IN STRONG AGREEMENT
OVERALL IN THE OVERALL EVOLUTION/PLACEMENT/STRENGTH AND TIMING OF
THE LARGER SCALE TROF THROUGH THURSDAY INTO EARLY FRIDAY AS THE
UPPER LOW SHIFTS TO SASK/MANITOBA LINE WITH THE AMPLIFYING
SHORTWAVE DROPPING INTO THE SNAKE RIVER VALLEY AND NORTHERN
BASIN/RANGE REGION OF NV/UT. THE 00Z UKMET IS THE MOST AMPLIFIED
WITH THIS SECONDARY WAVE EVEN CLOSING A 558DM LINE 12Z FRI; THIS
WILL EVENTUALLY KEEP IT A BIT SLOWER AS THE TRAILING TROF THROUGH
THE NORTHERN ROCKIES AND SHEARING THROUGH THE N GREAT PLAINS SAT;
THOUGH THIS IS NOT TOO DETRIMENTAL TO ITS SENSIBLE WX/LOW LEVEL
MASS FIELDS.

OVERALL THE MAIN DIFFERENCE WAS THE ABSORPTION/BINARY INTERACTION
WITH THE CLOSED LOW OVER THE SOUTHERN CANADIAN PRAIRIES AND THE
SMALLER VORT CENTER OVER SE NW TERRITORIES ON FRIDAY.  ALL
GUIDANCE WITH EXCEPTION OF THE GFS DREW THE SHORTWAVE SOUTHWARD
WHICH SWINGS TOWARD THE BASE OF THE TROF BY THE END OF THE
SHORT-RANGE FORECAST PERIOD...ALLOWING FOR A SLIGHT SOUTHEASTWARD
SHIFT OF THE UPPER LOW ITSELF.  THE 12Z GFS SHIFTED TRACKS AND NOW
DRAWS THE VORT CENTER SOUTH AND ADJUSTS TOWARD THE 12Z NAM/UKMET
OVERALL...THOUGH STILL THE SLOWEST OVERALL.  THERE REMAINS MODEST
SPREAD TOWARD LATE SUN BUT GIVEN THE DETAILS ARE IN THE MESO/STORM
SCALE A GENERAL MODEL BLEND WILL SUFFICE BUT CONFIDENCE IS ONLY
AVERAGE OVERALL.


SUBTLE PRECURSORY SHORTWAVE ENERGY EXITING ROCKIES LATE THURS
AHEAD OF MAIN UPSTREAM TROF SPURRING SURFACE LOW THAT TRACKS
ACROSS MS AND OH VALLEYS TOWARD MID-ATLANTIC FRI/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS AND 00Z ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE

MODELS ALL SHOW SOME WEAK SHORTWAVE ENERGY MOVING EAST IN ZONAL
FLOW ACROSS N MO INTO OH VALLEY  FRIDAY INTO SATURDAY...WITH A
POSSIBLE SURFACE LOW REFLECTION AS WELL.  THE 12Z NAM CONTINUES
THE TREND SET BY THE 00Z RUN WITH THE STRONGEST
REPRESENTATION/CONVECTING MUCH EARLIER WITH UPSCALE FEEDBACK.  THE
00Z CMC SHOWS SUPPORT OF THIS SOLUTION BUT BOTH MEMBERS ARE ALSO
THE MOST AMPLIFIED WITH THE RIDGING NORTH OF IT PROVIDING GOOD
OUTFLOW CHANNELS...THAT MAY NOT COME TO FRUITION.  THE 12Z GFS/00Z
UKMET AND A HANDFUL OF ECENS MEMBERS SUPPORT THIS AS WELL BUT JUST
A BIT LATER WITH LESS OF A SURFACE REFLECTION.  AS SUCH WILL
CONTINUE TO PREFER THE LESS AMPLIFIED SITUATION GIVEN THE LOWER
LIKELIHOOD OF HAVING THE PERFECT ALIGNMENT OF ALL LEVELS TO
FEEDBACK TO THE NAM/CMC SOLUTIONS (EVEN THOUGH IT DOES REMAIN
PLAUSIBLE).  THIS IS BEST REPRESENTED BY THE 12Z GFS AND 00Z
ECMWF/UKMET BLEND.


WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/

GALLINA

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.