Prognostic Meteorological Discussion
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000
FXUS10 KWNH 241913
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
212 PM EST TUE JAN 24 2017

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

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

12Z MODEL EVALUATION INCLUDING FINAL PREFERENCES/FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...CLOSED LOW LIFTING ACROSS NORTHERN MID-ATLANTIC/NEW ENGLAND...
...STRONG SURFACE LOW LIFTING NORTHEAST TO COASTAL NEW ENGLAND...

PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

ALL OF THE MODELS TAKE THE ANOMALOUSLY STRONG UPPER LOW OFFSHORE
OF THE NORTHERN MID-ATLANTIC STATES TO A POSITION OFFSHORE OF THE
SOUTHERN NEW ENGLAND COAST EARLY WEDNESDAY/ATLANTIC CANADA BY
EARLY THURSDAY...EVENTUALLY TAKING ON A NEG TILT AS IT LIFTS OUT
TO SEA BY DAY 3. THE ASSOCIATED SURFACE LOW GRADUALLY LIFTS
ALONG/JUST OFFSHORE OF THE NEW ENGLAND COAST THROUGH EARLY
THU...UP INTO THE GULF OF MAINE BY LATER DAY 2. THE 12Z GFS AND
00Z/24 ECMWF TEND TO BE A BIT BETTER RESOLVED WITH THE ELONGATED
NATURE OF THIS SYSTEM BY THE END OF THE PERIOD AND THE SURFACE
LOWS ARE VERY WELL CLUSTERED WITH THEIR RESPECTIVE ENSEMBLES. A
MULTI-MODEL CONSENSUS AND A BLEND OF THESE SOLUTIONS REMAINS THE
PREFERENCE AT ABOVE AVERAGE CONFIDENCE.

19Z UPDATE: 12Z NAM REMAINS SLOWEST WITH TIMING...WITH THE
REMAINDER OF GUIDANCE IN REASONABLY GOOD AGREEMENT THROUGH THE
PERIOD. A GENERAL MODEL BLEND REMAINS FAVORED...AGAIN AT ABOVE
AVERAGE CONFIDENCE.


...LONGWAVE TROUGH/SURFACE LOW EJECTING OUT THROUGH THE PLAINS...
...ATTENDANT COLD FRONT PUSHING ACROSS THE EAST THROUGH THURSDAY...

PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE UPPER TROUGH EMERGING FROM THE INTERMOUNTAIN WEST AT MIDDAY
WEST WILL LIFT ACROSS THE NORTHERN AND CENTRAL PLAINS
WEDNESDAY...BEFORE PUSHING ACROSS THE OHIO VALLEY INTO THE MID
ATLANTIC/NORTHEAST BY DAY 3. MODELS REMAIN WELL-RESOLVED IN
PLACEMENT OF DEVELOPING SURFACE LOW PRESSURE LIFTING ACROSS THE
MID-MISSISSIPPI RIVER VALLEY INTO THE GREAT LAKES THROUGH
WEDNESDAY NIGHT. THE ATTENDANT TRAILING SURFACE COLD FRONT WILL
SWEEP ACROSS THE OHIO VALLEY/MID-SOUTH THURSDAY...TOWARD THE EAST
COAST BY LATE THURSDAY. WHILE THE 12Z/NAM REMAINS SLIGHTLY
STRONGER AND SLOWER OFF TO THE NORTH AS PER ITS BIAS...THE 12Z GFS
HAS TRENDED A BIT FARTHER SOUTH WITH THE SURFACE FRONT TOWARD THE
00Z ECMWF/UKMET...AS WELL AS THE 00Z GEFS/ECENS MEAN. THEREFORE A
GENERAL ECMWF/GFS BLEND IS FAVORED WITH SLIGHTLY ABOVE AVERAGE
CONFIDENCE.

19Z UPDATE: 12Z CMC IS A STRONG/LOW OUTLIER WITH THE UPPER TROUGH
LIFTING ACROSS THE OHIO VALLEY/GREAT LAKES. 12Z ECMWF/UKMET LOOK
TO BE IN GOOD AGREEMENT WITH 12Z GFS...WITH EACH OF THESE AND
THEIR RESPECTIVE ENSEMBLES HANDLING MASS FIELDS SIMILARLY WITH
THIS FEATURE THROUGH THE PERIOD. A GENERAL MODEL BLEND WEIGHTED
TOWARD THE GFS/UKMET/ECMWF IS PREFERRED.


...SHORTWAVE APPROACHING THE WEST COAST LATE WED/EARLY THURSDAY...

PREFERENCE: 60% 12Z GFS/ 40% 12Z ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A NARROW BUT ELONGATED TROF WILL EXTEND FROM THE GULF OF AK TO
ABOUT 40N BY 12Z WED WITH AN ACCOMPANYING COLD FRONT.
DOWNSTREAM...AN EQUALLY NARROW RIDGE WILL CONTINUE TO AMPLIFY INTO
SW CANADA AND ALLOW THE TROF ENERGY TO UNDERCUT THE RIDGE BY
THURSDAY MORNING BRINGING LIGHT SHOWERS. THERE IS GOOD MODEL
AGREEMENT...WITH ONLY MINOR TIMING DIFFERENCES WITH THIS SYSTEM
THROUGH 12Z THURSDAY. AFTER THURSDAY NIGHT...THERE IS INCREASED
MODEL SPREAD WRT HOW
TO HANDLE THE SHORTWAVE ENERGY INTO FRIDAY AS IT DROPS ACROSS THE
DESERT SOUTHWEST. MODELS HANDLE NORTHERN STREAM COMPONENT
SIMILARLY. THE 00Z ECMWF IS STRONGEST WITH THE SOUTHERN STREAM
ENERGY PLUNGING INTO THE BASE OF THE SHORTWAVE...BUT 12Z/GFS HAS
TRENDED IN ITS DIRECTION WITH THIS FEATURE AS WELL.  PREVIOUS 12Z
GFS/00Z ECMWF REFLECTS A STRONGER/TIGHTER AND SLOWER EVOLUTION OF
THE SHORTWAVE TROUGH AS A WHOLE INTO THE WEST COAST AND IS
PREFERRED. GIVEN THE TIME RANGE...WILL KEEP PREFERENCE AT ONLY
SLIGHTLY ABOVE AVERAGE.

19Z UPDATE: 12Z MODELS HAVE CONTINUED THEIR TREND OF BECOMING
FARTHER SOUTH/STRONGER WITH THE DIGGING TAIL/AXIS OF THE UPPER
TROUGH ACROSS THE SOUTHWEST. GIVEN THE INCREASING AGREEMENT...WILL
MIX IN SOME UKMET TO THE FINAL MODEL PREFERENCE.

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

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

MONTEFUSCO

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