weather.gov     
National Weather Service

Prognostic Meteorological Discussion
NWS Homepage
This page is being discontinued on March 12, 2014.
The same data is available at this site. Please update your bookmarks.
Thank you, and we apologize for the inconvenience.
Please send an email to SR-SRH.Webmaster@noaa.gov with any concerns.


Current Version
Previous Version:    01  02  03  04  05  
[Printable]
287
FXUS10 KWNH 240643
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 AM EDT THU APR 24 2014

VALID APR 24/0000 UTC THRU APR 27/1200 UTC

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

...AN EVALUATION OF THE 00Z CMC/ECMWF/UKMET ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...STRONG CLOSED LOW EXITING INTO THE CANADIAN MARITIMES MIDDAY
THURSDAY...

FINAL PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: HIGH

A BROAD NEGATIVELY-TILTED TROF CURRENTLY ANCHORING THE
NORTHEASTERN CONUS WILL SHIFT EASTWARD EARLY THIS MORNING AND
DEVELOP INTO A CLOSED LOW OFFSHORE. IN GENERAL THE MODELS ARE VERY
CLOSE TO ONE ANOTHER SO WILL FAVOR A GENERAL MODEL COMPROMISE FOR
THIS SYSTEM.


...PAIR OF SYSTEMS MOVING IN TANDEM TOWARD THE UPPER GREAT
LAKES/OH VALLEY...RESPECTIVELY...
...ASSOCIATED SURFACE LOWS MARCHING EASTWARD...

FINAL PREFERENCE: BLEND OF THE 00Z ECMWF/UKMET
FORECAST CONFIDENCE: BELOW AVERAGE

MODELS DEPICT SPLIT FLOW IN PLACE WITH A PAIR OF SYSTEMS SLIDING
EASTWARD WHILE BEING NEARLY IN TANDEM. WITH THE NORTHERN STREAM
UPPER TROF...THE 00Z CMC/UKMET/ECMWF ALL ARE A BIT SLOWER THAN THE
CONSENSUS NOTED FURTHER DOWNSTREAM WHICH INCLUDES THE ENSEMBLE
MEANS. EVENTUALLY THIS SYSTEM DEVELOPS A CLOSED LOW ACROSS
SOUTHERN ONTARIO BY 26/0000Z WHILE THE OTHER BATCH OF ENERGY
SHEARS AND MOVES THROUGH THE MID-ATLANTIC FRIDAY EVENING. ENSEMBLE
SURFACE LOW PLOTS AGREE THAT A PAIR OF SURFACE WAVES WHICH
ACCOMPANY THIS SYSTEM WITH THE SOUTHERN MOST LOW DOMINATING. THE
INITIAL STRONG CLUSTERING WHICH WAS IN PLACE ACROSS UPSTATE NY AT
26/0000Z HAS CHANGED AS THE 00Z CMC/ECMWF/UKMET ARE NOW ALL
FURTHER SOUTH WITH THE CYCLONE CENTER. EVENTUALLY MODELS DEVELOP A
WAVE OFF THE DELMARVA COAST WITH THE 00Z ECMWF TRENDING DEEPER
WHICH FOLLOWS IN LINE WITH THE 00Z GFS. ALSO...THE 00Z ECMWF
FOLLOWS IN LINE WITH ITS ENSEMBLE MEAN WHICH WAS NOT THE CASE WITH
THE PREVIOUS ECMWF RUN. THE PREFERENCE WITH THIS SYSTEM HAS BECOME
A LITTLE MORE CHALLENGING GIVEN THE MODELS KEEP FLUCTUATING WITH
PLACEMENT/TIMING. WILL HAVE TO LEAN MORE ON GUIDANCE WHICH FAVOR
THE MORE STABLE ENSEMBLE MEANS WHICH WOULD BE THE 00Z ECMWF/UKMET.
CONFIDENCE IS A LITTLE MORE LIMITED SO WILL LOWER IT FROM THE
PREVIOUS PREFERENCE.


...DEEP UPPER TROF CROSSING THE DESERT SOUTHWEST/FOUR CORNERS
REGION THIS WEEKEND...
...POWERFUL SURFACE CYCLONE ACROSS THE MIDDLE OF THE U.S...

FINAL PREFERENCE: BLEND OF THE 00Z CMC/ECMWF
FORECAST CONFIDENCE: BELOW AVERAGE

THE FLOW REALLY BEGINS TO AMPLIFY ACROSS THE SOUTHWESTERN CONUS BY
EARLY IN THE UPCOMING WEEKEND. THE 00Z NAM/GFS ARE QUICKER
EJECTING THIS SYSTEM TOWARD THE FOUR CORNERS REGION WITH
CORRESPONDING SUPPORT FROM THE 00Z GEFS/21Z SREF MEANS.
MEANWHILE...THE 00Z CMC/ECMWF ARE SLOWER WITH THE 00Z UKMET
SITTING SOMEWHERE IN THE CENTER OF THE SPREAD. THE PAST COUPLE OF
RUNS OF THE GUIDANCE SHOW THE NCEP MODELS HAVE CONSISTENTLY BEEN
ON THE FURTHER EAST SIDE OF THE MODEL ENVELOPE. THE SEPARATION IS
ALSO WELL ESTABLISHED IN THE PAST FOUR SPAGHETTI PLOTS ALTHOUGH
THE DIFFERENCES HAVE DECREASED. PER COORDINATION WITH WPC MEDIUM
RANGE ALONG WITH THE TENDENCY OF MODELS TO BE TOO QUICK TO EJECT
CLOSED LOWS OUT OF THE SOUTHWESTERN U.S...WILL FAVOR THE SLOWER
SOLUTIONS HERE. SUCH SOLUTIONS HAVE ACTUALLY ACCELERATED FROM
THEIR PREVIOUS RUNS BUT STILL ARE TO THE SOUTH AND WEST VERSUS THE
FASTER NCEP GUIDANCE. WILL MAINTAIN THE PREVIOUS SOLUTION BUT WILL
NOT UTILIZE THE 12Z ECMWF ENSEMBLE MEAN AS IT IS LIKELY TOO SLOW
NOW GIVEN THE 00Z MODEL TRENDS.


...NEXT PACIFIC SYSTEM REACHING THE PACIFIC NORTHWEST BY EARLY
SUNDAY...

FINAL PREFERENCE: BLEND OF THE 00Z GEFS/12Z ECMWF ENSEMBLE MEANS
FORECAST CONFIDENCE: BELOW AVERAGE

AS THE INITIAL UPPER TROF TRACKS TOWARD THE SOUTHERN HIGH PLAINS
BY EARLY SUNDAY...ANOTHER SYSTEM IS EXPECTED TO APPROACH THE
PACIFIC NORTHWEST COAST AT THE SAME TIME. THE 540-DM SPAGHETTI
PLOT SHOWS ENOUGH SPREAD IN THE GUIDANCE THAT A COMBINATION OF THE
MEANS WILL BE PREFERRED. WILL TAKE A SPLIT BETWEEN THE 00Z GEFS
MEAN AND 12Z ECMWF ENSEMBLE MEAN.



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

RUBIN-OSTER

$$






U.S. Dept. of Commerce
NOAA National Weather Service
1325 East West Highway
Silver Spring, MD 20910
E-mail: w-nws.webmaster@noaa.gov
Page last modified: May 16, 2007
NATIONAL WEATHER SERVICE: for Safety, for Work, for Fun - FOR LIFE