Re: next week
Posted by CypressTX on 1/28/2011, 3:09 pm
check out HPC's final extended discussion today


EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
136 PM EST FRI JAN 28 2011

VALID 12Z MON JAN 31 2011 - 12Z FRI FEB 04 2011



...MAJOR WINTER STORM SETTING UP NEXT WEEK FROM THE ROCKIES TO THE
NORTHEAST...


MEDIUM RANGE GUIDANCE IS AGREEABLE WITH THE LARGE SCALE SCENARIO
OF AN ELONGATED MEAN TROF EXTENDING FROM NERN CANADA SWWD INTO THE
SWRN CONUS... LIKELY WITH SOME SEPARATION BETWEEN SRN CANADA/NRN
TIER CONUS FLOW AND WRN/SRN CONUS FLOW.  THIS TROF WILL BE
SUPPORTED BY A MEAN RIDGE THAT SHOULD PERSIST OVER THE ERN PAC/WRN
CANADA ALBEIT WITH SOME CHANGE IN SHAPE OVER TIME.  WHILE A GOOD
CONSENSUS EXISTS WITH THE LARGE SCALE MEAN EVOLUTION... THERE IS
LOWER THAN AVERAGE CONFIDENCE IN DETAILS DUE TO THE SPLIT FLOW
NATURE OF THE NOAM PATTERN AND ADDITIONAL UNCERTAINTIES PRESENTED
BY ERN PAC ENERGY THAT MAY TRY TO PASS THRU THE MEAN RIDGE BY
MID-LATE WEEK.

THE MOST PROMINENT SFC SYSTEM FOR WHICH SHRTWV UNCERTAINTIES COME
INTO PLAY IS FCST TO TRACK NEWD FROM THE SRN PLAINS TUE ONWARD.
TO VARYING DEGREES THE 00Z GFS AND ECMWF HAVE MADE MEANINGFUL NWWD
ADJUSTMENTS FROM FAIRLY SUPPRESSED TRACKS IN MULTIPLE PREVIOUS
RUNS.  THE ECMWF TREND IS MORE EXTREME AS ITS PREVIOUS TWO RUNS
WERE ON THE SERN SIDE OF THE ENVELOPE AND THE NEW 00Z RUN IS NOW
ON THE NWRN SIDE OF GUIDANCE.  THE CANADIAN IS A FAST EXTREME TO
BRING SWRN CONUS ENERGY INTO THE PLAINS AND IS ALSO IN THE NWRN
PART OF THE SPREAD... WHILE THE UKMET TRACK IS NOT QUITE AS FAR
NWWD AS ITS PREVIOUS RUN.  OVERALL PREFER A GEFS MEAN/12Z ECMWF
ENSEMBLE MEAN SOLN THAT FALLS IN THE MIDDLE OF LATEST AND RECENT
GUIDANCE GIVEN THE SENSITIVITY OF SHRTWV DETAILS AND SIGNIFICANT
RUN TO RUN CONTINUITY CHANGES.

BEHIND THIS SYSTEM... BY WED NIGHT-FRI THERE IS CONSIDERABLE
SPREAD REGARDING ENERGY THAT MAY TRY TO PASS THRU THE ERN PAC MEAN
RIDGE.  THE 00Z ECMWF AND SLOWER 00Z GFS BOTH SEEM A LITTLE STRONG
SO THE ENSEMBLE MEAN BLEND USED FOR THE PLAINS/ERN CONUS SYSTEM
PROVIDES A MORE TOLERABLE SOLN AT THIS TIME.  THE GEFS MEAN IS A
LITTLE EXTREME WITH ITS SLOWER TIMING/WWD ELONGATION OF THE TROF
SETTLING OVER THE SWRN CONUS SO INCLUSION OF THE ECMWF MEAN TONES
DOWN THIS ASPECT OF THE FCST.

WHILE DAYS 5-7 WED-FRI FOLLOW A BLEND OF THE GEFS/12Z ECMWF
MEANS... MISSING DATA DUE TO EARLIER COMMS ISSUES PRECLUDED USE OF
THE ECMWF MEAN FOR DAYS 3-4.  THUS THE EARLIER PART OF THE FCST
STARTED WITH A BLEND OF GFS/ECMWF/GEFS MEAN SOLNS TO ARRIVE AT AN
ACCEPTABLE COMPROMISE.

UPDATED MORNING PRELIMS USE A MULTIMODEL BLEND OF 00Z
GFS/ECMWF/CMC/UKMET/GFS ENS MEAN. THE RESULT IS NEARLY IDENTICAL
TO THE EARLIER USED SOLUTION.

12Z MODEL GUIDANCE FOLLOWS CONTINUITY AND A COMPOSITE OF THE RUNS
WOULD CONTINUE TO YIELD THE BLENDED SOLUTION OF HPC. NO CHANGES
FOR AFTERNOON FINALS.

AS SHORTWAVE ENERGY MOVES INTO THE FOUR CORNERS REGION EARLY
TUESDAY AND ARCTIC HIGH PRESSURE PLUNGES DEEP INTO THE PLAINS WITH
GREATER THAN 20 DEGREE NEGATIVE  TEMPERATURE ANOMALIES. THIS WILL
BRING STRONG UPSLOPE FLOW INTO THE CO ROCKIES FRONT RANGE WITH
MDT/HVY SNOWFALL TO THE SRN ROCKIES SPREADING EWD INTO THE CENTRAL
PLAINS. MID LEVEL ENERGY SHEARS OUT EWD AND A MDT SFC LOW DEVELOPS
OVER ERN TX BY TUESDAY. THIS LOW MOVES NEWD INTO KY/TN WED AND
REFORMS OFF THE MID ATLC CAPES AND RAPIDLY MOVES NEWD OFF NOVA
SCOTIA BY THURSDAY. MDT TO HVY RAINFALL POTENTIAL SOUTH OF THE LOW
PRESSURE TRACK WITH SNOW ACROSS THE CENTRAL PLAINS AND MAINLY
NORTH OF THE OH RIVER AND MASON DIXON LINE INTO NEW ENG. HEAVY
SNOW THREAT INDICATED BY OPERATIONAL MODELS QPF OUTPUT/ANALOGS AND
FAVORABLE MID AND UPPER LEVEL JET STRUCTURE WITH ICING THREAT
ALONG THE CHANGE OVER AND THEN THE DAMMED IN AREA IN THE MID ATLC
PIEDMONT.  

PACIFIC RECON FLIGHTS REQUESTED INTO THE CRITICAL UNCERTAINTY AREA
AHEAD OF THIS SYSTEM IN THE NE PACIFIC. IF A FLIGHT IS AVAILABLE
THIS DATA COULD GET INTO THE MODEL SYSTEMS BY THE RUNS OF SUNDAY
00Z/12Z 30 JAN.
RAUSCH/ROSENSTEIN
Ñ
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next week - CypressTX, 1/28/2011, 11:56 am
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