National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS10 KWNH 180701
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT TUE JUN 18 2013

VALID JUN 18/0000 UTC THRU JUN 21/1200 UTC

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

FINAL 00Z MODEL EVALUATION...INCLUDING THE 00Z ECMWF AND FINAL
PREFERENCES


...BROAD UPPER LEVEL TROUGHING OVER THE GREAT LAKES AND
NORTHEAST...

PREFERENCE: NON 00Z NAM COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MOST RECENT GUIDANCE SHOWS DECENT AGREEMENT WITH BROAD UPPER
LEVEL TROUGHING AND A CLOSED CENTER TRACKING EASTWARD THROUGH
QUEBEC. THERE ARE A COUPLE OF TRAILING WAVE WHICH PROGRESS ACROSS
THE NORTHEAST.  ONE ON DAY TWO SHOWS THE NAM/21Z SREF MEAN WITH A
HIGHER AMPLITUDE WAVE THAN THE 00Z ECMWF/GFS/CANADIAN GLOBAL/UKMET
AND THE GEFS/ECMWF ENSEMBLE MEANS. THE MODEL MAJORITY PERSISTS
WITH THE SLOW MOVING TROUGH AXIS IN THE NORTHEAST ON DAY THREE
WHILE THE NAM EJECTS A WAVE OFF THE COAST AND STARTS RAISING
HEIGHTS IN RESPONSE TO THE FASTER MOVING CYCLONE IN THE NORTHWEST.
 THE BETTER THAN NORMAL CLUSTERING OF THE 00Z
GFS/ECMWF/CANADIAN/UKMET/GFS ENSEMBLE MEAN/ECMWF ENSEMBLE MEAN
SUGGESTS A NON-NAM CONSENSUS BE USED.

...LOW-MID LEVEL WAVE ADVANCING EAST ACROSS THE SOUTHERN
APPALACHIANS/MID-ATLANTIC/SOUTHEAST...
...WEAK SFC LOW TRACKING TOWARD THE CNTRL MID-ATLANTIC COAST...

PREFERENCE: 00Z ECMWF/UKMET/GEFS MEAN BLEND
CONFIDENCE: NEAR AVERAGE

A 700 MB SHORTWAVE AND ATTENDANT SFC LOW/FRONTAL BNDRY IS FORECAST
TO TRACK EWD FROM THE TN VALLEY ACROSS THE SOUTHERN APPALACHIANS
TO THE MID-ATLANTIC STATES.

THE 00Z ECMWF/UKMET CLUSTER WELL WHILE THE GFS FLIPPED TO A LOWER
AMPLITUDE AND FASTER SOLUTION. THE 00Z NAM/21Z SREF MEAN ARE
SLOWEST IN MOVING THE 700 MB TROUGH EAST...RESULTING IN LOW
PRESSURES LINGERING LONGER NEAR THE NC COAST.  WITH GOOD
CLUSTERING AMONG THE 00Z GFS/ECMWF/12Z ECMWF ENSEMBLE MEAN/00Z
UKMET/00Z CANADIAN GLOBAL...PREFER A BLEND OF THESE
SOLUTIONS...WITH LESS WEIGHT ON THE 00Z NAM/21Z SREF MEAN.


...DEEP CLOSED LOW MOVING ACROSS THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES...

PREFERENCE: BLEND OF THE 00Z GFS/ECMWF/UKMET
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

STARTING EARLY THU...MODELS BEGIN TO DIFFER WITH THE SPEED OF THE
CLOSED LOW MOVING THROUGH THE NORTHWEST. THE 00Z NAM/21Z SREF ARE
QUICKEST WITH THE CENTER OF THE CLOSED LOW DURING THE DAY THU.
THE 00Z GFS/12Z-00Z ECMWF/00Z CANADIAN GLOBAL/00Z UKMET ARE IN THE
SLOWER CLUSTER AND THE 18Z GEFS MEAN/12Z ECMWF ENSEMBLE MEAN
CLUSTER WELL WITH THESE SOLUTIONS.  GIVEN THE HIGH AMPLITUDE WAVE
PATTERN AND CLOSED LOWS USUALLY MOVE SLOWLY...PREFER A BLEND OF
THE GFS/ECMWF/UKMET AND THE 18Z GEFS MEAN/12Z ECMWF ENSEMBLE MEAN.
 THE ONE AREA THE GFS LOOKS LIKE A LOW PROBABILITY IS WITH ITS
LOWER PRESSURE IN RESPONSE TO CONVECTION THU NIGHT NEAR THE ND/MN
BORDER.  THE 00Z CANADIAN GLOBAL IS ON THE SOUTHWEST FRINGE OF THE
GUIDANCE SUITE AND IS CONSIDERED A LOW PROBABILITY SOLUTION.

...500 MB WAVE MOVING FROM THE CENTRAL PLAINS-UPPER MS VALLEY ON
DAY TWO AND OHIO VALLEY DAY THREE...

PREFERENCE:  BLEND OF THE 00Z GFS/21Z SREF MEAN
CONFIDENCE:  SLIGHTLY ABOVE AVERAGE

THE MODELS SHOW A LOW AMPLITUDE 500 MB WAVE MOVING EAST IN
CONFLUENT FLOW FROM THE CENTRAL PLAINS TO MS VALLEY ON DAY TWO AND
OHIO VALLEY ON DAY 3.  THERE ARE SLIGHT TIMING AND AMPLITUDE
DIFFERENCES WITH THE WAVE AMONGST THE MODELS/ENSEMBLE MEANS.  THE
NAM WAS THE HIGHEST AMPLITUDE SOLUTION...WITH THE 00Z
ECMWF/CANADIAN GLOBAL LOWER IN AMPLITUDE. CLUSTERING IS GOOD AMONG
THE 00Z GFS/12Z ECMWF/21Z SREF MEAN/18Z GEFS MEAN TO SUGGEST A
BLEND OF THESE SOLUTIONS BE USED. THE 00Z ECMWF HAS HIGHER HEIGHTS
IN THE OHIO VALLEY BY 12Z FRI THAN ITS MEAN...SO UNCERTAINTY
SUGGESTS USING A CONSENSUS/MEAN SOLUTION.


...MODEL TREND GRAPHICS AT
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
...500 MB FORECASTS AT
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

PETERSEN

$$