Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8
000
FXUS10 KWNH 210638
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 AM EDT TUE OCT 21 2014

VALID OCT 21/0000 UTC THRU OCT 24/1200 UTC

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

...AN EVALUATION OF ALL 00Z MODEL GUIDANCE 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.


...SHEARING MID-LEVEL ENERGY OVER SOUTHERN NM/FAR WEST TX...

FINAL PREFERENCE: GENERAL MODEL CONSENSUS
FORECAST CONFIDENCE: HIGH

A BATCH OF VORTICITY SLIDING ACROSS NORTH-CENTRAL MX WILL CONTINUE
TO SHEAR AS IT NEARS THE RIO GRANDE. ALL MODELS AGREE ON THIS
OCCURRING DURING THE NEXT 12 TO 24 HOURS SO WILL RECOMMEND A
GENERAL MODEL CONSENSUS GIVEN THE AGREEMENT.


...SHORTWAVES CROSSING THE GREAT LAKES REGION EARLY ON...
...COASTAL STORM AFFECTING THE NORTHEASTERN U.S. COAST WEDNESDAY
THROUGH FRIDAY...

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

WATER VAPOR IMAGERY SHOWED A PAIR OF IMPULSES MOVING THROUGH THE
CENTRAL APPALACHIANS AND LOWER GREAT LAKES...RESPECTIVELY.
EVENTUALLY THE SYSTEM BECOMES BETTER ORGANIZED AS IT CLOSES OFF
ALOFT FORMING A CLOSED LOW OVER THE MID-ATLANTIC BY TUESDAY
EVENING. THROUGH 36 HOURS/WEDNESDAY MORNING...MODELS SHOW
SUFFICIENT AGREEMENT BEFORE DIFFERENCES EMERGE WITH THE COASTAL
DEVELOPMENT. THE ENSEMBLE SURFACE LOW PLOT BY 22/1200Z SHOWS THE
12Z GEFS MEMBERS BEING WEST OF THE 12Z ECMWF/CMC ENSEMBLE MEMBERS.
THIS SEPARATION HAS BEEN NOTED IN THE 3 OF THE PAST 4 PLOTS DATING
BACK TO MODELS RUN 36 HOURS AGO. HOWEVER...BY 23/0000Z...THE 12Z
ECMWF ENSEMBLE MEMBERS ARE CLOSER TO THE COAST. IN SPITE OF THIS
SEPARATION...THE CURRENT ENSEMBLE MEANS...00Z GEFS/21Z SREF/12Z
ECMWF ARE FAIRLY IN LINE WITH ANOTHER. THE 00Z GFS/ECMWF AGREE
REASONABLY WITH THIS WHILE THE 00Z CMC/UKMET ARE DISPLACED TO THE
NORTH AND EAST. SUCH A SOLUTION APPEARS TO HOLD STEADY THROUGHOUT
THE REMAINDER OF THE SHORT RANGE PERIOD. WILL CONTINUE WITH THE
PREVIOUS SOLUTION AND RAISE THE CONFIDENCE UP TO AVERAGE NOW.


...STRONG SHORTWAVE CURRENTLY MOVING INTO NORTHERN CA...
...EVENTUAL SPLIT FLOW OVER THE CENTRAL U.S. BY MID-WEEK....

FINAL PREFERENCE: BLEND OF THE 00Z GFS/ECMWF/CMC (WEIGHTED MORE
TOWARD THE GFS/ECMWF)
FORECAST CONFIDENCE: BELOW AVERAGE

A PRONOUNCED SHORTWAVE CURRENTLY PUSHING INTO NORTHERN CA WILL
QUICKLY LIFT NORTHEASTWARD TOWARD THE NORTHERN GREAT BASIN DURING
THE NEXT 24 HOURS. AGREEMENT IS MUCH BETTER THAN RECENT DAYS WHERE
SOME OF THE GUIDANCE TRIED TO ALLOW SHORTWAVE ENERGY TO SINK
SOUTHWARD TOWARD THE FOUR CORNERS REGION. THE FORECAST BECOMES
MORE UNCERTAIN THEREAFTER AS SOME OF THE MID-LEVEL VORTICITY LIFTS
INTO CENTRAL CANADA WHILE THE REMAINING ENERGY TRACKS ALONG THE
NORTHERN TIER MID-WEEK. THE 00Z CMC/UKMET APPEAR TO HAVE CHANGED
GEARS AND SHIFTED AWAY FROM THEIR PREVIOUS SOLUTIONS. BOTH OF
THESE MODELS ALLOW MORE ENERGY TO CROSS THE NORTHERN TIER OF THE
CONUS. TO VARYING DEGREES THE 00Z GFS/ECMWF/CMC SHOW REASONABLE
AGREEMENT WITH ONE ANOTHER. THE 00Z UKMET INITIALLY IS AMONG THIS
CLUSTERING BUT IT EVENTUALLY CARRIES A CLOSED LOW ACROSS THE LOWER
MO VALLEY BY EARLY FRIDAY WHICH HAS LITTLE SUPPORT IN THE
ENSEMBLES. OVERALL UNCERTAINTY STILL REMAINS ON THE HIGHER SIDE BY
ONE LOOK AT THE 576-DM SPAGHETTI PLOT. RUN-TO-RUN CONTINUITY HAS
NOT BEEN THE GREATEST SO WILL KEEP THE CONFIDENCE BELOW AVERAGE
WITH THIS SYSTEM. WPC WILL FAVOR A COMBINATION OF THE 00Z
GFS/ECMWF/CMC WITH MORE WEIGHTING ON THE GFS/ECMWF AS THEY AT
LEAST WERE SOMEWHAT CONSISTENT WITH THEIR 12Z RUNS.


...BROAD CYCLONIC FLOW ACROSS THE NORTHEASTERN PACIFIC WEDNESDAY
THROUGH FRIDAY...

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

IN THE WAKE OF THE INITIAL SYSTEM MOVING INTO THE INTERMOUNTAIN
WEST...THE MID-LATITUDE FLOW SEES THE AMPLITUDE DECREASE AND
BECOME A BIT MORE ZONAL IN NATURE. WITH LOWER HEIGHTS CENTERED
OVER THE NORTHEASTERN PACIFIC....A MYRIAD OF PROGRESSIVE
SHORTWAVES WILL BOMBARD THE PACIFIC NORTHWEST WITH ENHANCED
ONSHORE FLOW ACCOMPANYING EACH WAVE. THE MODELS INITIALLY HAVE A
DECENT HANDLE ON THE PATTERN BEFORE UNCERTAINTY INCREASES. MORE
SPECIFICALLY...THE GUIDANCE BEGINS TO STRUGGLE WITH THE TIMING OF
THE NEXT ROUND OF HEIGHT FALLS APPROACHING THE NORTHWESTERN U.S.
LATE IN THE WORK WEEK. THE 552-DM SPAGHETTI PLOT SHOWS THE 12Z
GEFS MEMBERS BEING EAST OF THE SLOWER 12Z ECMWF ENSEMBLE MEMBERS.
THE SPREAD BETWEEN THESE TWO ENSEMBLE MEANS HAS DECREASED
RECENTLY...PARTICULARLY COMPARED TO THE 00Z MODEL CYCLE THE
PREVIOUS DAY. WILL SPLIT THE DIFFERENCE BETWEEN THESE TWO ENSEMBLE
MEANS UNTIL THE SPREAD DIMINISHES.


...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

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.