Prognostic Meteorological Discussion
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FXUS10 KWNH 281846
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
145 PM 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 FINAL 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: 12Z ECMWF... WHICH IS A COMPROMISE BETWEEN
THE GFS/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 UKMET/CANADIAN AND SREF MEAN
WOBBLE IN AND OUT OF THE BETTER CONSENSUS BUT THE UKMET
EGREGIOUSLY LAGS BEHIND THE OTHER MODELS WITH THE SFC LOW IN
CANADA BY LATE TUESDAY. DIFFERENCES BETWEEN THE QUICKER GFS AND
SLOWER NAM AVERAGE OUT TO SOMETHING LIKE THE 12Z ECMWF SOLUTION...
WHICH FITS THE GEFS/ECENS MEANS CONSENSUS. 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: 12Z GFS
CONFIDENCE: BELOW AVERAGE

MODELS DIFFER ON HOW TO HANDLE THIS ENERGY AND THEIR PREVIOUS RUNS
SHOW RATHER POOR CONTINUITY. RECENT TREND HAS SEEMED TO BE TOWARD
A SLOWER AND POSSIBLY CLOSED OFF SOLUTION ALONG MUCH OF THE
CALIFORNIA COAST. 12Z UKMET WAS THE QUICKER/WEAKER OUTLIER.
CONSIDERING THE BREADTH OF THE ENSEMBLES VS THE DETERMINISTIC
GUIDANCE... WILL HEDGE TOWARD A SLOWER/DEEPER SOLUTION VIA THE 12Z
GFS... WHICH NOW APPEARS TO BE A GOOD COMPROMISE SOLTUTION AT
LEAST AT 500MB. PLEASE REFERENCE THE QPF DISCUSSION FOR MORE
INFORMATION.


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

12Z NAM/ECMWF LIE NEAR EACH OTHER AS THE SFC LOW DEVELOPS OFFSHORE
NEW ENGLAND EARLY MONDAY BUT THE NAM IS QUICKER TO DEEPEN THE LOW.
ENSEMBLES SUGGEST A POSITION IN BETWEEN THE NAM/ECMWF AND THE GFS.
UKMET/CANADIAN WERE A BIT QUICKER AND LIE JUST EAST OF THE BROADER
CONSENSUS. PREFER TO SIDE WITH THE BETTER CONSENSUS AT THIS TIME
AND A BLEND BETWEEN THE GFS/ECMWF SHOULD SUFFICE.


COLD FRONT PUSHING THROUGH THE HIGH PLAINS MONDAY INTO TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: 12Z ECMWF
CONFIDENCE: AVERAGE

12Z GFS/GEFS AND 09Z SREF MEAN LIE ON THE QUICKER SIDE OF THE
GUIDANCE SPREAD WHILE THE NAM/ECENS MEAN AND EPECIALLY THE UKMET
LIE ON THE SLOWER SIDE. THE 12Z ECMWF OFFERS A MOST REASONABLE
COMPROMISE SOLUTION THAT LIES CLOSE TO THE CANADIAN... WHICH TIES
BACK NICELY TO THE SOUTHERN SFC LOW DISCUSSED IN THE FIRST
SECTION.


...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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