Prognostic Meteorological Discussion
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807
FXUS10 KWNH 190413
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1112 PM EST WED JAN 18 2017

VALID JAN 19/0000 UTC THRU JAN 22/1200 UTC

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

00Z EVALUATION INCLUDING MODELS PREFERENCE AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

CLOSED UPPER LOW OVER CNTRL/SRN HIGH PLAINS TRACKING TO UPPER MS
VALLEY/GREAT LAKES FRI WITH
ASSOCIATED SURFACE WAVE INTO THE OHIO VALLEY FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: AVERAGE

THE CLOSED LOW CURRENTLY OVER THE SOUTHERN HIGH PLAINS SWINGS THE
BASE THROUGH THE LOWER MS VALLEY EARLY AND SWINGS THROUGH TO THE
EAST COAST BY FRIDAY EVENING.  THIS ALLOWS FOR THE TROF TO OPEN
AND ELONGATE WHILE GOING NEGATIVE TILT ACROSS THE EASTERN HALF OF
THE US.  THE 00Z NAM AND GFS CONTINUE THE OVERALL GENERAL
CONSENSUS OF THIS EVOLUTION AS PRESENTED BY THE 12Z
GUIDANCE/ENSEMBLE SUITE.  AS SUCH A GENERAL MODEL BLEND CAN BE
CONSIDERED AT SLIGHTLY ABOVE AVERAGE CONFIDENCE.


LONG WAVE TROUGH DIGGING INTO THE SOUTHWEST US THU/THU NIGHT WHILE
DEVELOPING/CLOSING MID LEVEL LOW OVER THE CENTRAL PLAINS BY EARLY
SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

WITH THE LARGE SCALE RIDGING OVER THE EAST COAST/WESTERN ATLANTIC
WITH LARGE SCALE TROF OVER THE EASTERN PACIFIC...THE NEXT WAVE
CURRENTLY CRASHING THE WEST COAST WILL PIVOT THROUGH THE
INTERMOUNTAIN WEST AND CONSOLIDATE THE BASE OF THE TROF ACROSS THE
SOUTHWEST INTO THE NM/CO TOWARD FRIDAY MORNING.  THE TRACK OF THE
UPPER LOW WILL BE RETARDED BY THE EXITING OPENING WAVE AHEAD OF IT
IN THE UPPER MIDWEST ALLOWING FOR MORE OF A NEGATIVE TILT AND
NEARLY NORTHWARD TRACK ACROSS THE CENTRAL PLAINS THROUGH THE EARLY
WEEKEND WITH AN ACCOMPANYING BROAD SURFACE REFLECTION.  MODELS ARE
IN GENERAL GOOD AGREEMENT OVERALL WITH BEST OVERALL ALIGNMENT
NOTED WITH THE 12Z ECMWF AND THE 00Z GFS.  THE 00Z NAM IS ALSO
QUITE SIMILAR BUT FAVORS A BIT FURTHER STRENGTH NORTHWEST ALONG
THE AXIS INTO THE DAKOTAS.  A GENERAL MODEL BLEND MAY BE
SUFFICIENT BUT GIVEN STRENGTH OF ALIGNMENT OF THE GFS/ECMWF WILL
PREFER THESE SOLUTIONS FOR A TIGHTER BLEND WITH SLIGHTLY ABOVE
AVERAGE CONFIDENCE.


SECONDARY HEIGHT FALLS ACROSS THE WEST FRIDAY/SATURDAY WHILE BASE
ROLLS THROUGH THE SOUTHWEST INTO THE SOUTHERN PLAINS BY SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: AVERAGE

GOES WEST WV SHOWS THE NEXT ROBUST CONSOLIDATED SHORTWAVE
APPROACHING THE WEST COAST CURRENTLY BETWEEN 160-170W NORTH OF
40N.  THIS WAVE RAPIDLY APPROACHES WITH HIGH MODEL AGREEMENT WITH
ADDITIONAL STRONG JET STREAK UNDERCUTTING IT.  AS THE WAVE NEARS
THE NORTHWEST COAST LATE FRIDAY...THE INNER CORE IS A BIT MORE
ELONGATED E-W BUT UNDER STRONG MODEL AGREEMENT INCLUDING THROUGH
TO THE DEEP SURFACE REFLECTION.  HIGH CONFIDENCE IN THE MASS
FIELDS CONTINUES THROUGH ITS EVENTUAL FILING AND LIFTING NORTHWARD
TOWARD THE END OF THE FORECAST PERIOD THOUGH THE 12Z ECMWF/CMC AS
IS TYPICAL BY DAY 3 ARE A BIT SLOWER TO WIND DOWN THAN THE GFS/NAM
WITH THE UKMET IN BETWEEN.  STILL A GENERAL MODEL COMPROMISE WILL
SUFFICE THROUGH THIS PORTION OF THE LARGER SCALE TROF.

FURTHER SOUTH...THE STRONG JET ENERGY MUCH LIKE THE PRIOR WAVES
WILL DIG SOUTHWARD AND REINFORCE THE BROAD GLOBAL TROF OVER THE
INTERMOUNTAIN WEST AS THE SHORTWAVE ENERGY STREAKS ACROSS THE
SOUTHWEST SAT.  BY LATE SAT INTO SUNDAY UNDER INCREASING DIFFLUENT
FLOW...THE LEAD SHORTWAVE ENERGY WILL BEGIN TO LEAD TO A DEEP
CYCLOGENESIS ACROSS TX AND LOWER MS VALLEY SUNDAY.   THE 00Z GFS
CONTINUES TO BE MOST CONSOLIDATED AND MOST CONCENTRIC AND SLIGHTLY
SLOWER THAN THE REST OF THE GUIDANCE INCLUDING THE 12Z ECMWF/ECENS
MEAN...THOUGH OVERALL THE TWO CAMPS ARE QUITE AGREEABLE TO THE
OVERALL ENSEMBLE SPREAD AS WELL AS THE OVERALL LAST FOUR-CYCLE
TREND.  STILL ALL BUT THE 00Z GFS SUGGEST SOME SHED SHORTWAVE
ENERGY THAT IS QUICKER ACROSS THE GULF STATES THAT SUPPORT
DOWNSTREAM SURFACE CYCLOGENSIS AND ACCOMPANYING SFC MOISTURE
FLUX/QPF RETURN OVER THE SOUTHEAST SAT NIGHT INTO SUNDAY MORNING.
THE 00Z ECMWF/CMC ARE MOST SUPPRESSED WITH THIS ADDITIONAL FASTER
SHORTWAVE/JET STREAK AND ARE MUCH FURTHER EAST.  THE 00Z NAM AND
12Z UKMET SUGGEST A VERY STRONG SHORTWAVE FEATURE THAT LEADS TO A
MUCH FURTHER SURFACE REFLECTION THAT IS NOT GENERALLY SUPPORTED IN
THE 12Z ENSEMBLE SURFACE CLUSTER.   ALL CONSIDERED A 00Z GFS/12Z
ECMWF BLEND MATCHES BEST WITH THE ENSEMBLE SUITE AS A WHOLE WHILE
THE 12Z PARALLEL/OPERATIONAL GFS DO SUPPORT THE 12Z ECMWF A BIT
MORE...TO SUGGEST INCREASED WEIGHT TOWARD THE ECMWF IN THE BLEND
AS A WHOLE.  CONFIDENCE IN A GFS/ECMWF BLEND IS ONLY AVERAGE EVEN
THOUGH THE SPREAD IS FAIRLY GOOD FOR DAY 3...THE POTENTIAL FOR
RATHER LARGE MODEL/PREFERENCE CHANGES ARE POSSIBLE GIVEN THE
PROGRESSIVE FLOW AND THIS WAVE IS STILL WELL UPSTREAM OF THE WEST
COAST AT THIS TIME.


APPROACH OF NEXT STRONG CLOSED LOW NEARING WEST COAST SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/ECENS MEAN/18Z GEFS
CONFIDENCE: SLIGHTLY BELOW AVERAGE

IN THE WAKE OF PRIOR SYSTEM WITH DIGGING STRONG JET ACROSS THE
SOUTHWEST...THE NEXT ROBUST WAVE APPROACHES THE WEST COAST AND
SUPPORTS PUMPING UP RIDGING ACROSS THE WESTERN US IN ADVANCE OF IT
WITH FAIRLY GOOD ENSEMBLE AGREEMENT.  THIS ALLOWS FOR THE WAVE TO
ALSO AMPLIFY AND CONSOLIDATE JUST NORTH OF THE 40N130W BENCHMARK.
SPREAD IN THE SOLUTIONS APPEARS TO BE IN THE INTERACTION/SPACING
WITH RESPECT TO THE NORTHWEST PORTION OF SHORTWAVE/VORTICITY
ENERGY OF THE PRECEDING WAVE.  THE 00Z GFS IS A CLOSER/FASTER IN
TIMING TO THE PRECEDING WAVE AND THEREFORE PRODUCES A SOLUTION
FURTHER NORTH AND WEST OF THE REMAINING GUIDANCE AS WELL AS MUCH
DEEPER OVERALL.  THIS BREAKS AWAY FROM THE 18Z GEFS SOLUTION THAT
WAS A BIT FURTHER SOUTH AND CLOSER TO THE 12Z ECWMF (WHICH APPEARS
TO BE THE MIDDLE GROUND SOLUTION).  THE 12Z UKMET IS VERY SIMILAR
IN EVOLUTION TO THE ECMWF BUT ALSO IS ABOUT 6-9HRS SLOWER THAN THE
ECMWF...A STRANGE SET UP SCENARIO WITH RESPECT TO THEIR
HISTORY/BIAS.  THE 12Z CMC IS ALSO SIMILAR BUT GENERALLY WEAKER
AND FASTER THAN THE ECMWF AND AWAY FROM THE ENSEMBLE MEANS.  THE
00Z NAM IS SHOWS A SLOWER TREND LIKE THE UKMET BUT ALSO APPEARS TO
HAVE SOME SECONDARY INTERACTION/INNER CORE STRONG VORT CENTERS
THAT DO NOT APPEAR CONSISTENT WITH THE OVERALL SETUP/ENSEMBLE
SOLUTIONS.   ALL CONSIDERED THE 12Z ECWMF IS A BEST REPRESENTATION
OF THE ENSEMBLE SPREAD...HOWEVER WILL INCLUDE THE 18Z GEFS/12Z
ECENS MEAN TO ENCOMPASS THE SPREAD AT THIS POINT.  CONFIDENCE IS
SLIGHTLY BELOW AVERAGE.


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

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

GALLINA

$$





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