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FXUS10 KWNH 081826
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
125 PM EST MON FEB 08 2016

VALID FEB 08/1200 UTC THRU FEB 12/0000 UTC

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

12Z NAM/GFS EVALUATION INCLUDING THE UKMET/CANADIAN/ECMWF AND
PREFERENCES

LOW PRESSURE FORMING OFF THE MID-ATLANTIC COAST TONIGHT/TUESDAY...

PREFERENCE: 3-WAY BLEND NAM/GFS/ECMWF
CONFIDENCE: AVERAGE

SMALL-SCALE DIFFERENCES EMBEDDED WITHIN THE UPPER TROUGH COMBINED
WITH MODESTLY STEEP MID LEVEL LAPSE RATES AND CLOSE PROXIMITY TO
THE LINGERING MOISTURE GRADIENT OFF THE COAST ARE CONTRIBUTING TO
CONTINUED MODEL SPREAD AND THEREFORE UNCERTAINTY WITH THE LOW
TRACK...ITS DEPTH...AND EVEN TIMING. THE NAM HAS THE ADVANTAGE OF
RECENT INITIALIZATION AND HIGH RESOLUTION BUT LIES NEAR THE STRONG
EDGE OF THE GUIDANCE AND IS CLOSER TO THE COAST BY LATE TUESDAY
COMPARED WITH MOST OTHER SOLUTIONS AND IS AGAINST RECENT TRENDS
FOR A LOW MORE OFFSHORE. THE GFS HAS A LOW TRACK AND DEPTH NEAR
THE CONSENSUS AND THEREFORE OFFERS ADVANTAGES BUT IS ALSO NEAR THE
COLD EDGE OF THE GUIDANCE ALOFT CONTRIBUTING TO ASCENT AND
MOISTURE SHIELDS THAT LIES NEAR THE HIGH END OF THE GUIDANCE. THE
06Z PARALLEL GFS IS MORE SUBDUED WITH THE COLDNESS ALOFT AND MAY
AFFORD AN EVEN MORE RELIABLE SOLUTION. THE 00Z AND 12Z ECMWF ARE
NEAR THE SOUTHERN AND WEAKER EDGES OF THE GUIDANCE BUT HAVE
SUPPORT FROM THE ITS OWN ENSEMBLE MEAN/SREF MEAN. THUS...THE MOST
PREFERRED APPROACH IS A CONSENSUS OF THE MOST DESIRABLE SOLUTIONS
THAT MAXIMIZES PREDICTABILITY WHILE ALSO ADDRESSING UNCERTAINTY.

LONGWAVE TROUGH EXTENDING SOUTHWARD FROM THE GREAT LAKES TUE-WED...
SURFACE TROUGH OVER NEW ENGLAND...

PREFERENCE: NAM
CONFIDENCE: AVERAGE

THE NAM REPRESENTS THE MODEL CONSENSUS THROUGH THIS PERIOD...WITH
THE ECMWF NEAR THE SOUTHERN EDGE OF THE GUIDANCE AND THE GFS NEAR
THE COLD EDGE OF THE GUIDANCE THAT APPEARS TO TRANSFER TO A
STRONGER SURFACE TROUGH OVER NEW ENGLAND ON THURSDAY THAN
PREFERRED AT THIS TIME.

LOW PRESSURE MOVING FROM MONTANA TO TEXAS WED-THU...

PREFERENCE: GFS
CONFIDENCE: AVERAGE

ALTHOUGH THE NAM IS A LITTLE STRONGER WITH THE LOW FORMING IN THE
LEE OF THE CANADIAN ROCKIES COMPARED TO THE GFS...THEY ARE
CONCEPTUALLY SIMILAR EARLY ON AND STRONGER THAN THE ECMWF TRACKING
SOUTHEASTWARD WITH A ZONE OF FRONTOGENESIS. LATE IN THE PERIOD
HOWEVER...THE NAM MOVES TOWARD THE EASTERN EDGE OF THE
GUIDANCE...ECMWF TOWARD THE SOUTHERN EDGE...AND THE GFS REMAINING
NEAR THE CONSENSUS AND THUS IS MOST RECOMMENDED.

SHORTWAVE TROUGH INFLUENCING THE PACIFIC NORTHWEST WED-THU...

PREFERENCE: NAM OR ECMWF
CONFIDENCE: ABOVE AVERAGE

THE GFS LIES NEAR THE STRONG AND FAST EDGES OF THE GUIDANCE AND
MAY BE SHOWING ITS OCCASIONAL FAST BIAS. GIVEN THE STRONG RIDGE
ACROSS THE WEST AT THIS TIME...THE PREFERENCE IS FOR PERSISTENCE
AND THEREFORE THE WEAKER NAM/ECMWF.

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

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


$$





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