Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8
234
FXUS10 KWNH 210626
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
125 AM EST SAT JAN 21 2017

VALID JAN 21/0000 UTC THRU JAN 24/1200 UTC

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

00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SHORTWAVE TROUGH OVER THE OHIO VALLEY TODAY...WEAKENING THROUGH
EARLY SAT MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW STRONG SIMILARLY AND CONTINUITY WITH THIS SYSTEM
TO CONTINUE GENERAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE.


COMPACT CLOSED MID-LEVEL LOW ADVANCING THROUGH THE CNTRL PLAINS
TODAY AND REACHING THE UPPER MS VALLEY SAT NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE 00Z GFS/NAM SHOW VERY SIMILAR EVOLUTION/TRACK TO THE UPPER LOW
AND ASSOCIATED SURFACE WAVE (INCLUDING THE INTERACTION/SURFACE
TROUGHING TOWARD THE DAKOTAS) THROUGH SUNDAY ENOUGH TO CONTINUE A
GENERAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE.


HEIGHT FALLS ACROSS THE WEST TODAY...CLOSED LOW ACROSS THE LOWER
MS VALLEY SUN WITH ASSOCIATED STRONG SURFACE LOW LIFTING INTO THE
MID-ATLANTIC TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/GFS BLEND
CONFIDENCE: AVERAGE

LAST 4 CYCLES OF ENSEMBLE SPAGHETTI/CLUSTER ANALYSIS SHOWS THE
SLIGHTLY FASTER LIFTING OF THE (SECTION ABOVE) WAVE LIFTING NORTH
OUT OF WI PLAYS A SIGNIFICANT CHANGE IN THE EVOLUTION OF THIS WAVE
MAINLY AFTER SUNDAY AS IT LIFTS NORTH.  THE WEAKER NORTHWEST WAVE
SUPPORTS A BIT OF INCREASED RIDGING ACROSS THE NORTHWEST ATLANTIC
AND FIRST NOTED WITH YESTERDAY`S 00Z ECMWF ALLOWS FOR A SLIGHT
WESTERN SHIFT AS THE TROF ELONGATES NW-SE ACROSS THE UPPER TN
VALLEY AND MID-ATLANTIC.  WHILE THE 12Z ENSEMBLE SUITE SHOWS THIS
CHANGE COMPARED TO THE PRIOR 3 CYCLES...THE 12Z CMC/UKMET ARE
SLOWER TO MAKE THE CHANGE AND HAVE A SIMILAR EVOLUTION TO PRIOR
CYCLES.  HOWEVER...THE 12Z CMCE MEAN LOOKS QUITE SIMILAR TO THE
00Z NAM ACROSS THE MID-ATLANTIC.

THE 00Z NAM WHILE A MIDDLE GROUND SOLUTION TO BOTH ENSEMBLE
MEANS...IS INITIALLY LESS FAVORABLE SHOWING SOME OVER
AMPLIFICATION OF THE LEAD SHORTWAVE EJECTING ACROSS THE LOWER MS
VALLEY INTO THE LOWER OHIO VALLEY SUNDAY NIGHT...MAKING IT OUT OF
PHASE IN SHAPE/PLACEMENT AND STRENGTH TO THE PATTERN AS A
WHOLE...MAKING IT LESS DESIRABLE THROUGHOUT THE FORECAST PERIOD.
THE 00Z GFS LIKE THE LAST FEW RUNS SHOWS GOOD AGREEMENT TO THE
ENSEMBLE MEAN BUT TOWARD THE END OF DAY 3 (TUESDAY) BECOMES QUICK
AND MUCH MORE ELONGATED IN THE MORE AMPLIFIED FLOW BUT OVERALL
COMPARED TO THE 12Z ECMWF IS QUITE AGREEABLE.   WOULD FAVOR THE
12Z ECMWF A BIT HIGHER IN WEIGHTING IN A 00Z GFS/12Z ECMWF BLEND.
CONFIDENCE IS AVERAGE IN THIS BLEND COMING TO FRUITION WITHIN THE
MODEST SPREAD.

07Z UPDATE: THE 00Z ECMWF SHOWED VERY LITTLE CHANGE PERHAPS A BIT
BROADER TOWARD THE END OF THE FORECAST PERIOD...KEEPING FAIRLY
GOOD CONFIDENCE WITH THE INITIAL PREFERENCE.   THE 00Z CMC/UKMET
BOTH TRENDED TOWARD THE GFS/ECMWF BUT REMAIN A BIT MORE
CONCENTRIC...SLOWER AND SOUTHEAST WITH THE MID-LEVEL LOW TO FULLY
INCORPORATE THEM AT THIS TIME...BUT OVERALL THE SPREAD CONTINUES
TO REDUCE OVERALL.  STILL WPC PREFERENCE WILL REMAIN AN ECMWF
DOMINANT BLEND WITH THE 00Z GFS.


COLD FRONT REACHING THE WEST COAST SAT NIGHT AND LONGWAVE TROUGH
OVER THE WEST COAST BY MON MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE DETERMINISTIC AND ENSEMBLE SUITE CONTINUE TO SHOW REMARKABLE
AGREEMENT WITH THE LARGER SCALE MID-LEVEL LONGWAVE BUT GENERALLY
PROGRESSIVE TROF AS IT TRACKS ACROSS THE NORTHEAST PACIFIC INTO
THE WESTERN THIRD OF THE US BY 12Z TUESDAY.  THE SPREAD REMAINS
WITH THE PLACEMENT AND SHAPE/TIMING OF THE ANTICYCLONIC WOBBLE OF
THE INNER CORE OF THE UPPER LOW THAT IS THE MAIN DRIVER TO THE
DEVELOPMENT OF THE DEEP SURFACE REFLECTION THAT BOTTOMS OUT AROUND
22/12Z ALONG 130W WEST OF OR/WA.  THE 12Z NON-NCEP SUITE AND 00Z
NAM HAS GENERALLY GRAVITATED TOWARD A MORE COMMON SOLUTION THOUGH
THE DEPTH OF THE LOWER TROPOSPHERE WITH ONLY SMALL SPLITS WEST TO
EAST OF THE LOW (UKMET-NAM TO ECMWF/CMC) WEAKENING NEAR N CA COAST
BY 12Z TUES.   THE 00Z GFS INNER CORE CONTINUES TO ENTER THE
WOBBLE A BIT FURTHER NORTH WEST INCREASING INTERACTION WITH
REMAINING SHORTWAVE ENERGY FROM PRIOR UPPER LOW.  THIS LEADS TO A
FURTHER NORTH AND WEST COUNTER-CLOCKWISE WOBBLE AND EMPHASIZES A
MUCH DEEPER WAVE ALONG THE NW CA COAST AT THE END OF THE FORECAST
PERIOD.  A SUCH A NON-GFS BLEND IS PREFERRED AT SLIGHTLY ABOVE
AVERAGE CONFIDENCE GIVEN THE SPREAD BETWEEN THE GFS AND NON-GFS
MEMBERS IS NOT SIGNIFICANTLY LARGE FOR SUCH A VAST SYSTEM.

07Z UPDATE: WHILE THE SPREAD WAS SMALL BETWEEN THE 00Z GFS AND
REST OF THE GUIDANCE..THE 00Z NON-NCEP SOLUTION SHIFTED EVER SO
SLIGHTLY TOWARD THE 00Z GFS WITH THE INNER CORE OF THE MID-LEVEL
LOW. THE UKMET/GFS REMAIN A BIT FASTER/WEST OF THE ECMWF/CMC AS
THE LOW DESCENDS IN LATITUDE NEARING THE COAST TUES BUT THIS SEEMS
MINOR ENOUGH TO SUPPORT A GENERAL MODEL BLEND AT SLIGHTLY ABOVE
AVERAGE CONFIDENCE.


www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

GALLINA

$$





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