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 261859
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM EDT SUN MAR 26 2017

VALID MAR 26/1200 UTC THRU MAR 30/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...CLOSED MID-LEVEL LOW WEAKENING INTO THE GREAT LAKES/NORTHEAST
THROUGH MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.


...NORTHERN STREAM TROUGH EJECTING ACROSS THE NORTHERN
PLAINS/UPPER MIDWEST TODAY/MON AND REACHING THE ONTARIO/QUEBEC
BORDER TUES MORNING...
...POSSIBLE SHORTWAVE PHASING OVER NEW ENGLAND BY WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PREFERENCE: BLEND OF THE 12Z UKMET/ECMWF
CONFIDENCE: BELOW AVERAGE

A COMPLEX INTERACTION OF SYSTEMS LEADS TO A LOW CONFIDENCE
FORECAST. WHILE THE 12Z GFS AND 00Z ECMWF APPEAR FAVORABLE WITH A
VORT MAX CROSSING THE CNTRL APPALACHIANS EARLY ON TUE...ENSEMBLE
SPREAD AND POOR RUN TO RUN CONTINUITY LOWERS CONFIDENCE WITH THE
NRN PORTION OF THE ENERGY INVOLVED DEVELOPING OVER SERN CANADA.
ENSEMBLE SCATTER LOW PLOTS SUPPORT A SURFACE LOW TRACK WEST OF THE
12Z GFS AND 00Z ECMWF TUE NIGHT/WED MORNING...WITH THE 06Z GEFS
MEAN AND 00Z ECMWF MEAN SUPPORTING A TRACK CLOSER TO THE 12Z
NAM/00Z UKMET. THE 12Z NAM HAS SOME UNDESIRABLE CHARACTERISTICS
WITH A FASTER/NORTHERN LEADING EDGE OF THE VORT TRACKING TO THE
SOUTH AND INTO THE ATLANTIC BUT MAY HAVE SOME USE ACROSS THE
NORTHEAST. AGAIN...CONFIDENCE IS VERY LOW WITH THIS SYSTEM.

19Z UPDATE...THE 12Z ECMWF/UKMET APPEAR TO BE FAVORABLE WITH THE
SRN VORT...ACTUALLY ONLY THE 12Z NAM APPEARS TO TAKE THE NRN TRACK
RIGHT NOW MAKING IT LESS LIKELY...SEE BELOW SECTION. A MORE IDEAL
INTERACTION WITH THE CLOSED LOW OVER SERN CANADA BY TUE/WED APPEAR
BETTER MATCHED TO THE 12Z ECMWF/UKMET GIVEN THESE MODELS HAVE
BETTER MATCHES TO THE ENSEMBLE CLUSTERING WITH SPAGHETTI HEIGHTS
AND SURFACE LOW TRACKS.

...UPPER TROUGH CURRENTLY OVER THE CNTRL HIGH PLAINS AND WEAKENING
INTO THE OH VALLEY/NORTHEAST MON NIGHT/TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE...BECOMING BELOW AVERAGE BY END OF PERIOD

THERE HAVE BEEN TRENDS IN THE GUIDANCE TO BE FASTER...OR CLOSER TO
THE 12Z GFS HERE BUT ONLY THE 12Z NAM STANDS OUT SIGNIFICANTLY
WITH A FARTHER NORTH TRACK OF THE MID-LEVEL VORTICITY MAX COMPARED
TO THE REMAINING MODEL CONSENSUS. THE 12Z ECMWF/UKMET/CMC ONLY
REINFORCE THAT IDEA GIVEN THEIR AGREEMENT TO ONE ANOTHER AND THE
ENSEMBLE MEANS...NOT SUPPORTING THE 12Z NAM. POSSIBLE INTERACTION
WITH A NRN STREAM SYSTEM MAKES FOR A COMPLICATED FORECAST BEYOND
12Z/28. HERE...THE ENSEMBLE MEANS SUPPORT A SHIFT IN PREFERENCE
TOWARD THE 12Z ECMWF/UKMET WHICH BETTER MATCH THE PREVIOUS
PREFERENCE FOR THE 00Z UKMET AND GEFS MEAN. SEE ABOVE SYSTEM FOR
ADDITIONAL DETAILS.


...UPPER TROUGH/COLD FRONT REACHING THE WEST COAST TODAY...
...WEAKER NORTHERN STREAM TROUGH OVER THE NORTHWEST MON/TUES...
...CLOSED LOW EVOLUTION INTO THE SOUTHWEST MON/TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM (OTHER MODELS USABLE AT SELECT TIMES)
CONFIDENCE: AVERAGE

THE 12Z GFS CONTINUES TO TREND FASTER...TOWARD THE FASTER EDGE OF
THE ENSEMBLE SPREAD THROUGH TUE. THE 12Z ECMWF HAS ALSO TRENDED
FASTER...SOMEWHAT SIMILAR TO THE 12Z GFS BUT THESE MODELS ARE ON
THE FASTER EDGE OF THE LATEST ENSEMBLE SPAGHETTI PLOTS. THE 12Z
UKMET/CMC TRENDED SLOWER AND MORE IN LINE WITH THE ENSEMBLE
CONSENSUS. WHILE THE 12Z GFS ENDS UP WITH A MORE FAVORABLE TIMING
COMPARED TO THE 12Z ECMWF BY 00Z/30...IT MAY BE DISPLACED TOO FAR
NORTH WITH THE MID-LEVEL LOW WHILE THE 12Z UKMET BEGINS TO
ELONGATE THE MID-LEVEL LOW MORE THAN THE REMAINING GUIDANCE. WHILE
THERE HAS BEEN SOME CONVERGING OF SLOWER/FASTER ENSEMBLE GUIDANCE
SINCE YESTERDAY...THE GFS/ECMWF APPEAR TO BE TOO QUICK GIVEN THE
LATEST...SHRINKING ENSEMBLE DISTRIBUTION.


...COLD FRONT WEAKENING INTO BRITISH COLUMBIA ON TUES...
...ONSHORE FLOW INTO THE PACIFIC NORTHWEST THROUGH TUES NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

RELATIVELY MINOR ADJUSTMENTS MADE IN THE GUIDANCE OVER THE PAST
12-24 HRS SUPPORT THE MIDDLE GROUND REPRESENTED BY THE 12Z
NAM...12Z GFS AND 12Z ECMWF.


...SHORTWAVE/SURFACE LOW NEAR THE PACIFIC NORTHWEST BY WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/12Z ECMWF/12Z CMC BLEND
CONFIDENCE: AVERAGE

THE 12Z GFS APPEARS TOO AMPLIFIED WITH A SHORTWAVE APPROACHING THE
PACIFIC NORTHWEST GIVEN A LACK OF SUPPORT IN THE REMAINING
GUIDANCE. THE ENSEMBLE MEANS SUPPORT A TROUGH DEPTH AND SURFACE
LOW TIMING CLOSER TO THE 12Z NAM AND 12Z ECMWF. THE 12Z UKMET HAS
TIMING AND DEPTH ISSUES UPSTREAM AT 00Z/30...DISPLACED FROM THE
CONSENSUS.

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

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

OTTO

$$




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