Prognostic Meteorological Discussion
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FXUS10 KWNH 281657
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1156 AM EST SAT FEB 28 2015

VALID FEB 28/1200 UTC THRU MAR 04/0000 UTC

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

12Z PRELIMINARY MODEL EVALUATION
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


INITIAL UPPER LOW/TROUGH DRIFTING THROUGH CA/NV THRU MON
REMNANT MID-LEVEL ENERGY EJECTING ONTO THE CENTRAL PLAINS TUESDAY
ASSOCIATED SFC LOW MOVING OUT OF COLORADO TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: COMPROMISE BETWEEN THE 12Z GFS AND 00Z
ECMWF... NEAR THE 12Z NAM
CONFIDENCE: AVERAGE

AT 500MB... THE MODELS ALL CLUSTER NEAR A BROAD CONSENSUS
CONSIDERING THE OBSERVED TIMING DIFFERENCES OVER PAST RUNS AS THE
ENERGY SHEARS THROUGH THE SOUTHWEST MONDAY. AS A SFC LOW MOVES OUT
OF COLORADO EARLY TUESDAY... THE 00Z UKMET WOBBLES IN AND OUT OF
THE BETTER CONSENSUS WHILE THE CANADIAN LAGS BEHIND. DIFFERENCES
BETWEEN THE QUICKER GFS AND SLOWER ECMWF AVERAGE OUT TO SOMETHING
LIKE THE NAM SOLUTION... WHICH FITS THE GEFS/ECMWF ENSEMBLE MEANS
CONSENSUS. THE 09Z SREF MEAN APPEARS TO BE TOO QUICK. WILL PREFER
A SOLUTION NEAR THE ENSEMBLE MEANS WHICH LIES NEAR THE NAM.


SECONDARY SHORTWAVE ENERGY DIVING SOUTHWARD ALONG THE WA/OR COAST
EARLY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: 00Z ECMWF/UKMET BLEND
CONFIDENCE: BELOW AVERAGE

MODELS DIFFER ON HOW TO HANDLE THIS ENERGY AND THEIR PREVIOUS RUNS
SHOW RATHER POOR CONTINUITY. OVERALL... WOULD PREFER TO STAY AWAY
FROM THE COMPARATIVELY EXTREME SOLUTIONS LIKE THE 12Z NAM AND EVEN
THE 12Z GFS BY LATE TUESDAY AS THE ENERGY SWINGS THROUGH THE
NORTHERN BAJA. SUPPORT LIES NEARER TO THE 00Z ECMWF/UKMET WITH
LESS TENDENCY TO CLOSE OFF... BUT WILL AWAIT THE REST OF THE 12Z
GUIDANCE.


DEVELOPING SFC FRONT IN THE EAST SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE

BROAD WARM AIR ADVECTION WILL BE THE DRIVING FACTOR IN
PRECIPITATION IN THE EAST OVER THE NEXT TWO DAYS. AT 500MB/SFC...
LITTLE REFLECTION IS EVIDENT UNTIL LATER SUNDAY INTO MONDAY AS
NORTHERN STREAM ENERGY PUSHES THROUGH THE GREAT LAKES -- SEE NEXT
SECTION. PLEASE REFERENCE OUR QPF AND WINTER WEATHER DISCUSSIONS
FOR PRECIPITATION DIFFERENCES.


NORTHERN STREAM SHORTWAVE TRACKING FROM THE N CENTRAL U.S. ON SUN
TO
NEW ENGLAND ON MON
DEVELOPING SFC LOW OFF NEW ENGLAND EARLY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE

12Z NAM AND 00Z UKMET/CANADIAN ARE A BIT QUICKER AND LIE JUST EAST
OF THE BROADER CONSENSUS OF THE 12Z GFS/00Z ECMWF AND 06Z GEFS
MEAN/00Z ECMWF ENSEMBLE MEAN WITH THE SFC LOW TRACK OFF NEW
ENGLAND EARLY MONDAY. PREFER TO SIDE WITH THE BETTER CONSENSUS AT
THIS TIME.


COLD FRONT PUSHING THROUGH THE HIGH PLAINS MONDAY INTO TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: NON-12Z GFS/00Z CANADIAN BLEND
CONFIDENCE: AVERAGE

12Z GFS AND 00Z CANADIAN APPEAR TO BE TOO QUICK OVERALL BASED ON
THE REST OF THE GUIDANCE/ENSEMBLES WITH THE SURFACE LOW MOVING
THROUGH NORTHERN ONTARIO. THE GFS APPEARS TO BE TOO QUICK WITH THE
COLD FRONT PUSHING THROUGH MINNESOTA EARLY TUESDAY... WHICH TIES
BACK TO THE SOUTHERN SFC LOW DISCUSSED IN THE FIRST SECTION.
PREFER TO SIDE CLOSER TO THE ENSEMBLE CONSENSUS WHICH IS CLOSE TO
THE NAM.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...


FRACASSO

$$




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