SUMMARY AND CONCLUDING REMARKS
Jim Gurka (Satellite Lab)
Hydromet 00-2, 25 February 2000
QPF SESSION
(1)
24 HOUR OBSERVED RAINFALL ENDING AT 12OO UTC, FEBRUARY 21,
1996 IS PROVIDED AS A HANDOUT (24 HOUR SATELLITE AND RADAR
PRECIPITATION ESTIMATES ARE PROVIDED AS GIF FILES)
CAUTIONARY NOTE: DESPITE ALL OF THIS DATA, OUR KNOWLEDGE OF
THE TRUE OR REAL 24 HOUR PRECIPITATION ANALYSIS IS STILL LIMITED



(2)
3 OR MORE INCHES ARE OBSERVED:

OVER SOUTHERN CALIFORNIA IN ASSOCIATION
WITH: WV AND PW PLUMES, LARGE PRECIPITATION
EFFICIENCIES, AND THE JET STREAM; IN THIS CASE,
THE WV AND PW PLUMES ARE COLLOCATED

OVER NORTHERN CALIFORNIA IN ASSOCIATION WITH
THE DEVELOPING CYCLONIC CIRCULATION AND SQUALL
LINE --- OF COURSE OROGRAPHIC EFFECTS ARE
EXTREMELY IMPORTANT

ALONG THE WV PLUME IN SOUTHERN NEVADA, THE
RADAR SHOWS A SMALL AREA OF 3 OR MORE INCHES
1 TO 3 INCHES ARE OBSERVED:

ALONG THE PLUME AND JET AXIS FROM SOUTHERN
NEVADA (SATELLITE AND RADAR) TO UTAH AND COLORADO

ALONG THE COASTAL AND UPSLOPE REGIONS OF OREGON
IN ASSOCIATION WITH THE CYCLONIC CIRCULATION AND SQUALL
LINE
0 TO 1 INCH ARE NOTED IN THE NON-PLUME AREAS, IN AREAS NOT
DIRECTLY ASSOCIATED WITH THE CYCLONIC CIRCULATION, AND IN AREAS
OF DOWNSLOPE FLOW AND WITH FAST MOVING PRECIPITATION SYSTEMS;
SOME OF THE PRECIPITATION OVER IDAHO COULD HAVE RESULTED FROM
A DISSIPATING CYCLONIC CIRCULATION THAT EFFECTED THAT AREA ON
FEBRUARY 20
FROM USING THE TECHNIQUE IN THE HANDOUT THE ONLY AREAS THAT QUALIFY FOR
MORE THAN 3 INCHES ARE THE COASTAL AREAS OF SOUTHERN TO CENTRAL
CALIFORNIA. HOWEVER, THE PRESENCE OF AN UNSTABLE ATMOSPHERE IS NOT REAL
OBVIOUS --- THIS COULD LIMIT THE PRECIPITATION TO HEAVY AMOUNTS (AROUND 3
INCHES) BUT NOT THE EXTREME (6 INCHES OR MORE). FURTHERMORE, THE
TECHNIQUE DOES NOT ALLOW FOR MORE THAN 3 INCHES TO OCCUR WITH STRONG
LIFTING MECHANISMS (ESPECIALLY ONES THAT ARE INTENSIFYING/STRENGTHENING)
AND LIFTING MECHANISMS THAT ARE INTERACTING WITH OROGRAPHY. THIS WOULD
ACCOUNT FOR THE HEAVY RAIN IN NORTHERN CALIFORNIA THAT INCLUDES THE
MOUNTAIN AREAS.
THE 1 TO 3 INCHES IN SOUTHERN NEVADA, UTAH AND COLORADO WERE HARD TO
JUSTIFY IN THE PRECIPITABLE WATER AND PRECIPITATION EFFICIENCY ANALYSES.
HOWEVER, THE WATER VAPOR PLUME COLLOCATED WITH THE JET STREAM AND
OROGRAPHIC EFFECTS COULD ACCOUNT FOR THOSE AREAS OF 1 TO 3 INCH
PRECIPITATION. REMEMBER THAT WATER VAPOR IS LOCATED IN THE MIDDLE TO
UPPER LEVELS OF THE TROPOSHPERE AND CAN CREATE DEEP MOISTURE
CONDITIONS FOR MOUNTAINOUS AREAS.
DESPITE THE STRENGTH OF THE CYCLONIC CIRCULATION, COASTAL AND ADJACENT
AREAS OF WASHINGTON AND OREGON GENERALLY RECEIVED ONE INCH OR LESS OF
RAIN. POSSIBLY THIS LIGHTER RAIN WAS DUE TO THE RAPID MOVEMENT OF THE
PRECIPITATION SYSTEM AND RELATIVELY DRY CONDITIONS AS INDICATED BY THE
SYSTEM AND RELATIVELY DRY CONDITIONS AS INDICATED BY THE PRECIPITABLE
WATER AND PRECIPITATION EFFICIENCY PRODUCTS.
(3)
WHICH 6 HOUR PERIOD RECEIVED THE GREATEST PRECIPITATION AMOUNTS ???

EXTREMELY DIFFICULT TO ANSWER --- A FUNCTION OF THE "TIMING" OF
THE LIFTING MECHANISMS PASSING OVER THE AREA

THE PLUME SEEMS TO PERSIST DURING THESE TIME PERIODS WITH A
COUPLE OF DISTURBANCES ALONG AND JUST TO THE NORTH OF THE
PLUME. ALONG THE PLUME FROM SOUTHERN/CENTRAL CALIFORNIA TO
COLORADO THE ETA MODEL PREDICTS AN INCREASE IN THE 6 HOUR TIME
PERIOD ENDING FEBRUARY 21, 1200 UTC. HOWEVER, SATELLITE
ESTIMATES INDICATED THAT MOST OF THE PRECIPITATION OCCURRED
DURING FEBRUARY 20, 1200 UTC TO FEBRUARY 21, 0000 UTC. NEVADA AND
UTAH APPEARED TO HAVE A 6 HOUR MAX ENDING FEBRUARY 21, 0600 UTC.
"IT NEEDS TO BE NOTED THAT THE SATELLITE ALGORITHM AT THIS TIME DOES NOT ACCOUNT
FOR THE HEAVY WARM TOP PRECIPITATION THAT OCCURRED OVER AREAS SUCH AS THE
NORTHERN CALIFORNIA COASTAL AND MOUNTAIN AREAS."

PRECIPITATION IN THE AREAS TO THE NORTH OVER NORTHERN
CALIFORNIA TO WASHINGTON ARE ASSOCIATED WITH THE TIMING AND
APPROACH OF THE DEVELOPING CYCLONIC CIRCULATION. ACCORDING TO
THE PROGS OF THE APPROACHING CYCLONIC CIRCULATION IN THE WV
AND THE ETA MODEL FORECASTS (PREDICTED TO INTENSIFY), THE
HEAVIEST WOULD OCCUR IN THE LATTER TIME PERIODS FEBRUARY 21,
0000 UTC TO FEBRUARY 21, 1200 UTC.
(4)
QPF IS TRULY A "LEFT-HANDED SCIENCE" BASED ON INTUITION, EMPIRICISM,
SUBJECTIVITY, AND EXPERIENCES.
(5)
IN ADDITION TO OUR "LEFT-HANDED" GIFTS AND TALENTS, QPF REQUIRES AN
INTEGRATION (ASSIMILIATION) OF ALL SOURCES OF DATA AND ANALYSES: NUMERICAL
MODEL OUTPUT, SATELLITE, WSR-88D, GRIDED DATA, PC GRIDS, RE-ANALYSIS
(MESOSCALE ANALYSIS) OF SURFACE AND UPPER AIR DATA, ETC.
(6)
I BELIEVE THAT WE CAN PREDICT USEFUL (RELIABLE CATEGORIES OF PRECIPITATION
(0-24/24-48/AND MAYBE 48-72 HOURS IN ADVANCE) THAT RANGE BETWEEN:

0 - 1 INCH

1 - 3 INCHES

3 - 6 INCHES

GREATER THAN 6 INCHES
IT IS MY BELIEF THAT QUARTER INCH CATEGORIES
(E.G., 0.25/0.50/0.75/1.0) I ON MANY OCCASIONS BELONG IN
FANTASY LAND (EXCEPTION TO THIS MAY BE PARTS OF THE WESTERN REGION).
(7)
BE BRAVE, "REACH OUT IN FAITH", BE A QPFer AND DEVELOP THAT QPF CONFIDENCE.
QPF IS THE HEART OF THE NWS ADVANCED WARNING PROGRAM.
(8)
REMEMBER VERIFICATION IS A GREAT TEACHER AND PLEASE CALL HPC/NCEP FOR
GUIDANCE OR FOR "TLC" ANYTIME … 301-763-8343.
(9)
IF YOU HAVE A QPF TECHNIQUE TO SHARE OR JUST WANT TO DISCUSS ANY
THOUGHTS OR OBSERVATIONS --- I AM ALWAYS OPEN TO NEW IDEAS !!!
--- MY E-MAIL ADDRESS IS: Roderick.Scofield@noaa.gov OR 301-763-8251.
(10)
GOOD LUCK, KEEP PLUGGING AWAY, DON'T GET DISCOURAGED AND CONTINUE TO
MASTER YOUR "LEFT HANDED" FORECASTING SKILLS !!!!!!
PICK 4 AREAS WHERE 24 HOUR PRECIPITATION
(ENDING FEBRUARY 21, 1996 1200 UTC)
MEASURED AT A POINT WAS BETWEEN:
(A)
0.1 -
0.9 INCHES
(B)
0.9 -
1.9 INCHES
(C)
1.9 -
2.9 INCHES
(D)
> 2.9 INCHES