Prognostic Meteorological Discussion
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FXUS10 KWNH 020439
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1238 AM EDT THU OCT 02 2014

VALID OCT 02/0000 UTC THRU OCT 05/1200 UTC

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

==================================================
00Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES
==================================================
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
==================================================

...LARGE AND POWERFUL CYCLONE TO BECOME CENTERED OVER THE GREAT
LAKES...
...EFFECTS REACHING ALL THE CENTRAL AND EASTERN U.S...

PREFERENCE: BLEND OF 00Z NAM/GFS

A TROUGH EMERGING FROM THE SOUTHERN ROCKIES AND PLAINS WILL
UNDERGO STRONG CYCLOGENESIS IN THE GREAT LAKES. A STRONG FRONT
WILL DRY OUT THE LOW LEVELS IN THE CENTRAL AND EASTERN U.S. ALL
THE WAY TO FAR SOUTH TX AND FL BY SATURDAY. THE ASSOCIATED UPPER
TROUGH DIPS TO 3 OR 3.5 DEVIATIONS BELOW CLIMATOLOGY WHILE EQUALLY
ANOMALOUS 850 MB TEMPERATURES OVERSPREAD THE EASTERN AND SOUTHERN
U.S...LIKELY LEADING TO SOME FROST CONCERNS FROM THE GREAT LAKES
TO PERHAPS AS FAR SOUTH AS THE TENNESSEE VALLEY.

MODELS ARE SIMILAR...AS WOULD BE EXPECTED WITH SUCH A LARGE SCALE
AND CLASSICALLY ORGANIZED SYSTEM. THE LATEST 00Z NAM AND GFS FIT
WELL WITH THE ENSEMBLE MEANS...EVEN A LITTLE BETTER THAN DID THE
12Z ECMWF. THE 12Z CANADIAN IS ONE OF THE MORE OUTLYING SOLUTIONS
WITH ITS MATURING CYCLONE TUCKED BACK FARTHER WEST BENEATH THE
UPPER TROUGH FRIDAY EVENING AND SATURDAY. ALL OF THE MODELS
PREDICT A SIMILAR BREADTH AND MAGNITUDE OF COLD AIR TO SPILL INTO
THE U.S. AT 850-700 MB.


...UPPER LOW PULLING AWAY FROM NEW ENGLAND...

PREFERENCE: BLEND OF 00Z GFS WITH 12Z ECMWF/UKMET

THE LOW WILL HAVE DECREASING INFLUENCE ON THE WEATHER ALONG THE
NEW ENGLAND COAST THROUGH FRIDAY. NEARLY ANY MODEL COULD BE USED
ON DAY 1...BUT THE BEST CLUSTER IS THE
GFS/ECMWF/UKMET...ESPECIALLY BY FRIDAY WHEN THE NAM IS AN OUTLIER
TO THE SOUTH AND EAST AND THE CANADIAN IS AN OUTLIER WITH DEEPER
LOW PRESSURE REMAINING NEAR THE COAST.


...SHORTWAVE BRUSHING THE PACIFIC NORTHWEST FRI/SAT...

PREFERENCE: ANY OF THE OPERATIONAL MODELS

A PACIFIC TROUGH WILL DE-AMPLIFY AS IT MOVES INTO THE MEAN RIDGE
POSITION ACROSS BRITISH COLUMBIA FRIDAY. THE TROUGH WILL CARRY A
MINIMAL INCREASE OF MOIST ONSHORE FLOW WITH IT...POSSIBLY BRINGING
LIGHT PRECIPITATION WESTERN WASHINGTON AND POSSIBLY THE HIGHER
PEAKS IN THE NORTHERN ROCKIES. MODEL DEPICTIONS ARE SIMILAR TO ONE
ANOTHER.

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

BURKE
$$




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