# Presentation: 866161

##  IMPROVING SHORT RANGE HEAVY PRECIPITATION FORECASTING THROUGH RECOGNITION OF SATELLITE BASED SIGNATURES COMBINED WITH ANALYSIS OF UPPER AIR AND SURFACE DATA

-  IMPROVING SHORT RANGE HEAVY PRECIPITATION FORECASTING THROUGH RECOGNITION OF SATELLITE BASED SIGNATURES COMBINED WITH ANALYSIS OF UPPER AIR AND SURFACE DATA

**Overview**

- John Simko,  Satellite Services Division, NOAA/NESDIS, Camp Springs, MD

- 	In most cases, short term numerical model quantitative precipitation forecast guidance for heavy rainfall events is reliable.  There are times however when model precipitation forecast guidance is not quite as accurate as it could be due to its inherent limitations.  Examples of these limitations include systems affecting the West Coast of the United States where the lack of data over the Pacific Ocean can have an adverse affect on model initialization and the subsequent short term precipitation forecast.  Sub-grid scale processes, such as those modeled by convective parameterization schemes, can also lead to model forecast errors and poor short term rainfall forecasts.  The recognition of a developing heavy rainfall event can be obtained through the Geostationary Operational Environmental Satellites (GOES) Infrared/Visible Channels along with analysis of data
- received from the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I), the National Oceanic Atmospheric Administration (NOAA) Advanced Microwave Sounder Unit (AMSU), and the National Aeronautics and Space Administration (NASA) Tropical Rainfall Measuring Mission (TRMM) polar orbiting satellites.  In some of these cases the use of satellite data combined with surface and upper air data analysis near the beginning of the precipitation event or even just prior to the onset of the event can improve short term quantitative precipitation forecasts in both location and quantity and serve as an alert to the potential of an excessive rainfall event.

**Southern California/Southern Nevada/Arizona December 28-29, 2004**

- SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 01/09/05 1350Z
- SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-763-8678
- VALUES ARE MAX OR SGFNT EST.  OROGRAPHIC CORRECTION IN AUTO-ESTS.
- EST'S FM:/GOES12-CNTRL AND E. U.S./GOES10-W. U.S...
-                          LATEST DATA USED: GOES-10 1330Z JS
-                          NOAA AMSU:1130Z DMSP SSMI:0457Z
- .
- LOCATION...SOUTHERN CALIFORNIA/SOUTHERN NEVADA/WESTERN ARIZONA
- .
- ATTN WFOS...SGX..LOX..MTR..VEF..HNX..PSR..FGZ
- ATTN RFCS...CNRFC
- .
- EVENT...***BIG SURGE OF ADDITIONAL HEAVY RAINS ABOUT TO MOVE INTO S CA WHICH EVENTUALLY WILL ALSO SPREAD INTO S NV/W AZ. COORDINATED WITH HPC WITH LATEST QPFERD ALSO POINTING TOWARD MAJOR FLOOD THREAT FOR S CA ALL DAY.***
- .
- GOES AND MICROWAVE ANALYSIS AND TRENDS...WATER VAPOR IMAGERY SHOWS MID/UPPER LEVEL FLOW HAS AMPLIFIED IN THE PAST 12 HOURS WITH DARKENING ENTERING THE BASE OF THE SUBTROPICAL TROF ROUGHLY ALONG 25N BETWEEN 130-145W. HIGH CLOUDS OFF OF CENT CA ARE NOW MOVING NNE WHICH IS REALLY INDICATIVE OF HOW MUCH AMPLIFICATION IS TAKING PLACE. GOES HIGH DENSITY WINDS ARE PICKING UP ON SPEED MAX IN SUBTROPICAL STREAM OF 120KTS BETWEEN 25-30N 120-130W. THIS IS FORECAST TO APPROACH COASTAL N BAJA LATER THIS AFTERNOON AND ALONG WITH ADDITIONAL JET ACROSS THE GREAT BASIN WILL CREATE A FAVORABLE COUPLED JET STRUCTURE FOR A TIME. IR LOOP SHOWS A LARGE MASS OF ENHANCED CLOUD TOPS APPROACHING THE COAST OF S CA FROM SAN LUIS OBISPO COUNTY SOUTHWARD TO SAN DIEGO COUNTY THEN WELL OFFSHORE TO
- THE SW. HAVE BEEN MONITORING RADAR COMPOSITE LOOP AND IT APPEARS TO SHOW THAT MUCH OF THIS ENHANCEMENT ON SATELLITE IMAGERY IS ACTIVE WHICH CERTAINLY IS AN OMINOUS SIGN FOR THE AMOUNT OF RAINFALL THAT IS LIKELY TO OCCUR THROUGH THE DAY ACROSS S CA. EARLIER MICROWAVE PASSES ALSO REVEALED GOOD COVERAGE OF RAINFALL. CURRENT AMSU PASS(1130Z) HAS BEEN DISREGARDED FOR RAINFALL SINCE IT OBVIOUSLY IS NOT PICKING UP ON EVERYTHING. HOWEVER IT ALONG WITH EARLIER SSMI DATA DOES INDICATE A VERY IMPRESSIVE DIRECT FLOW OF 1.30" PW VALUES FROM THE TROPICS INTO S CA.
- .
- IR IMAGERY ALSO SHOWS CONVECTIVE CELLS JUST SW OF 30N125W AHEAD OF ONE OF THE EMBEDDED VORT CENTERS IN SUBTROPICAL TROF SPREADING NE. THIS CONVECTION IS STILL VERY FAR OFF THE COAST BUT NOT OUT OF THE QUESTION THAT SOME OF IT COULD APPROACH FAR S CA LATER TODAY AS CORE OF SUBTROPICAL TROF APPROACHES. RAIN RATES SHOULD CONTINUE TO INCREASE ACROSS MUCH OF THE AREA FROM SAN LUIS OBISPO/KERN TO AT LEAST AS FAR SOUTH AS W RIVERSIDE/ORANGE COUNTIES DURING THE NEXT SEVERAL HOURS. AN INCREASE IN RAINFALL RATES/COVERAGE SHOULD ALSO SPREAD DOWN ACROSS SAN DIEGO COUNTY SEVERAL HOURS FROM NOW IF NOT EVEN SOONER THAN THAT. BASED ON CURRENT OBSERVED RAINFALL RATES(SCATTERED .2"-.4"/HR) AND THE AMOUNT OF IR ENHANCEMENT OFFSHORE EXPECT RATES TO INCREASE TO AT LEAST .3"-.5"/HR WITH ISOLATED SPOTS OF BETWEEN .5"-1.0"/HR PARTICULARLY OVER THE FAVORED SW AND S FACING SLOPES AS THE DAY PROGRESSES FOR S CA. THIS MOISTURE PLUME AND EMBEDDED HEAVIER RAINS SHOULD ALSO SPREAD INTO S NV/W AND NW AZ LATER THIS AFTERNOON/EVENING FOR A SIGNIFICANT INCREASE IN FLOOD THREAT THERE AS WELL.
- .
- SEE NCEP HPC DISCUSSION AND QPF/S FOR FORECAST.
- .
- ....NESDIS SAB HAS BEEN ADDED TO 12 PLANET....
- .
- HTTP://WWW.SSD.NOAA.GOV/PS/PCPN/
- ...ALL LOWER CASE EXCEPT/PS/PCPN..
- [ONLINE SSD PRECIP PRODUCT INDEX.
- .
- LAT...LON 3500 12100 3700 11400 3500 11200 3200 11800

**Southern California January 7-11, 2005 **

- PUBLIC INFORMATION STATEMENT
- NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA  535 PM PST TUE JAN 11 2005
- ...PRELIMINARY RAINFALL TOTALS...
- THE FOLLOWING ARE PRELIMINARY RAINFALL TOTALS IN INCHES FOR THIS RAIN EVENT WHICH BEGAN LAST THURSDAY. THESE TOTALS ARE THE 5-DAY ACCUMULATED AMOUNTS THROUGH 400 PM TODAY.
- VENTURA COUNTY COAST
-           _***LA CONCHITA.................    8.00***_
- VENTURA COUNTY WESTERN VALLEYS
-           MATILIJA DAM................   20.83
- VENTURA COUNTY MOUNTAINS
-           NORDHOFF RIDGE..............   26.90
- LOS ANGELES COUNTY METROPOLITAN AREAS
-           LA AIRPORT..................    5.06
-           DOWNTOWN LA.................    6.82
-           LONG BEACH..................    5.70
-           SANTA MONICA ARPT...........    6.67
-           BEVERLY HILLS...............   11.45
- LOS ANGELES COUNTY MOUNTAINS AND FOOTHILLS
-           _***OPIDS CAMP..................   31.61***_
-           TANBARK.....................   24.10
-           MT. BALDY FS................   22.11

- PUBLIC INFORMATION STATEMENT
- NATIONAL WEATHER SERVICE FLAGSTAFF AZ
- 330 PM MST WED JAN 12 2005
- ...POWERFUL SERIES OF STORMS BRINGS IMPRESSIVE PRECIPITATION TOTALS TO NORTHERN ARIZONA...
-               THE FINAL STORM IN A SERIES OF POWERFUL WINTER STORMS TO AFFECT ARIZONA HAS MOVED EAST OF THE STATE. THESE STORMS WERE RESPONSIBLE  FOR RECORD RAINFALL AND SNOWFALL IN THE HIGHER TERRAIN...ALONG WITH RECORD RAINFALL AND FLOODING IN LOWER TERRAIN. ***THE FIRST STORM TO IMPACT NORTHERN ARIZONA FROM DECEMBER 28TH-29TH BROUGHT HEAVY RAINS TO ALL BUT THE HIGHEST ELEVATIONS. THIS HEAVY RAIN LED TO SEVERAL FLOODING EVENTS ON AREA STREAMS AND RIVERS FROM THE MOGOLLON RIM TO THE LOWER VALLEYS.*** THE SECOND STORM TO AFFECT THE AREA FROM JANUARY 3RD-4TH BROUGHT HEAVY MOUNTAIN SNOW AND MORE HEAVY RAINFALL TO VALLEY LOCATIONS OF YAVAPAI AND NORTHERN GILA COUNTIES. THE FINAL STORM IN THE SERIES MOVED THROUGH JANUARY 7TH-11TH WITH TWO SIGNIFICANT PERIODS OF PRECIPITATION...WITH RAIN AND SNOW AT HIGHER ELEVATIONS AND MORE RAIN AT LOWER ELEVATIONS. TOTAL PRECIPITATION AMOUNTS ACROSS NORTHERN ARIZONA (RAIN AND MELTED SNOW) FOR THE 15 DAY PERIOD OF DECEMBER 28TH THROUGH JANUARY 11 RECEIVED SO FAR AT THE NATIONAL WEATHER SERVICE OFFICE IN FLAGSTAFF INCLUDE:
- GRAND CANYON COUNTRY:
-     GRAND CANYON NORTH RIM 11.60
- YAVAPAI COUNTY MOUNTAINS AND VALLEYS:
-     CROWN KING              9.06
- OAK CREEK/SYCAMORE CANYON:
-     _***SEDONA                  6.68***_
-     _***OAK CREEK              11.58***_
- WESTERN MOGOLLON RIM:
-     FLAGSTAFF               8.80
- NORTHERN GILA COUNTY:
-     TONTO CK FISH HATCHERY 10.96
-     WORKMAN CREEK          11.70

- SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 12/29/04 1020Z
- SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-763-8678
- VALUES ARE MAX OR SGFNT EST.  OROGRAPHIC CORRECTION IN AUTO-ESTS..EST'S FM:/GOES12-CNTRL AND E. U.S./GOES10-W. U.S...
-                            LATEST DATA USED: GOES-10 1000Z JS
-                                              AMSU 0637Z
- .
- LOCATION...SOUTHERN CALIFORNIA/SOUTHERN NEVADA/ARIZONA
- .
- ATTN WFOS/RFCS...LOX..SGX..HNX..VEF..PSR..FGZ..TWC..CNRFC..CBRFC
- .
- EVENT...STRONG SYSTEM CONTINUES TO PROGRESS SLOWLY EASTWARD ACROSS S CA.
- .
- MICROWAVE DATA...NOT MUCH NEW TO TALK ABOUT HERE SINCE LAST MESSAGE. ***DID RECEIVE AN AMSU PASS SEVERAL HOURS AGO WHICH SHOWED THE CONTINUED TREND OF INCREASING PWS WITHIN PRIMARY RAIN BAND AFFECTING S CA. VALUES WERE NOW MAXING OUT BETWEEN .8"-1.0". THE PASS ALSO INDICATED THE DEEP TROPICAL MOISTURE PLUME DIRECTED AT BAJA/NW MEXICO/AZ HAD SHIFTED SLIGHTLY FARTHER TO THE NW. ***
- .
- GOES ANALYSIS AND TRENDS...IR/WATER VAPOR LOOPS NOW SHOW THE UPPER LEVEL DISTURBANCE OFF OF S CA HAS CAUGHT UP WITH THE BAROCLINIC BAND WHICH SEEMS TO HAVE GIVEN IT MORE OF AN EASTWARD PUSH DURING THE PAST COUPLE OF HOURS. DARKENING AREA ON WATER VAPOR IMAGERY WITH UPPER LEVEL IMPULSE SURGING SE PAST 35N135W IS ALSO HELPING TO ACCELERATE S CA SYSTEM EASTWARD. THIS HAS TAKEN THE HEAVIEST RAINS OUT OF SANTA BARBARA/VENTURA COUNTIES WITH THE BACK EDGE NOW OVER LOS ANGELES/E KERN COUNTIES. STILL SEE ENOUGH ENHANCEMENT OFFSHORE OF S CA TO PROLONG THE MODERATE TO HEAVY RAINS FOR POINTS STRETCHING FROM EAST LOS ANGELES COUNTY SE TO SAN DIEGO COUNTY FOR SEVERAL MORE HOURS WITH THE LONGEST DURATION OF HEAVIER RAINS OVER SAN DIEGO COUNTY. EXPECT RAIN RATES IN THE STRONGEST CONVECTIVE CELLS WITHIN THIS AREA TO REACH OR EXCEED 1"/HR ESPECIALLY IN THE FAVORED SW FACING SLOPES OF E LOS ANGELES/SW SAN BERNARDINO/W AND CENT RIVERSIDE/W SAN DIEGO COUNTIES. ***EARLIER PERSISTENT BAND STRETCHING FROM SAN DIEGO NORTHEASTWARD INTO S NV/NW AZ/SW UT HAS REMAINED IN PLACE AND IS NOW MERGING WITH PRIMARY BAND APPROACHING FROM THE WEST. MODERATE TO HEAVY RAINS SHOULD ALSO CONTINUE ALONG THIS AXIS FOR SEVERAL MORE HOURS PROLONGING AND EXPANDING THE FLOOD THREAT. FINALLY FOR POINTS FARTHER EAST INTO AZ...IR LOOPS STILL INDICATE MOSTLY WARMER CLOUD TOPS WITH SCATTERED SHOWERS SPREADING NE FROM OFF OF THE W COAST OF BAJA INTO AZ.HAVE NOTED A BIT OF AN INCREASE IN THE COVERAGE OF THIS ACTIVITY RECENTLY AND EXPECT A STEADY INCREASE THROUGH THE REMAINDER OF THE NIGHT INTO THE DAY ON WEDNESDAY AS EASTWARD MOVING DISTURBANCE OFF THE S CA COAST INTERACTS WITH STRONG SUBTROPICAL JET/MOISTURE WHICH HAS CREPT A BIT MORE***
***NW OVERNIGHT.***
- .
- SEE NCEP HPC DISCUSSION AND QPF/S FOR FORECAST.
- .
- ....NESDIS SAB HAS BEEN ADDED TO 12 PLANET....
- .
- HTTP://WWW.SSD.NOAA.GOV/PS/PCPN/
- ...ALL LOWER CASE EXCEPT/PS/PCPN..
- [ONLINE SSD PRECIP PRODUCT INDEX.
- .
- LAT...LON 3700 12200 3600 11000 3100 11200 3100 12200

- During the period of January 7-11, Southern California was hit with a tremendous deluge. The most significant rains fell during Sunday, January 8 through Monday, January 9. Figure 1 below shows a DMSP SSMI Precipitable Water composite image from approximately 05Z Jan 9. Note the appearance of greater than 1” (dark red shade) Precipitable Water values spreading northeastward from the tropics toward Southern California. Figure 2 is a GOES-10 Water Vapor image taken from approximately the same time showing the presence of a well defined subtropical shortwave well off the coast of Southern California. Darkening on the western and southern portions of the upper level disturbance is an indication of strong upper level winds diving southward and southeastward into the base of the trof which is a sign that the trof is still in the process of amplifying.

- Figure 3 below is a DMSP SSMI Precipitable Water image taken approximately 12 hours later (close to 18Z on Jan 9) showing that deep tropical moisture has surged well into Southern California. Precipitable Water values were now analyzed at up to 1.3” within the moisture plume which is approximately 300% of normal climatology values for this portion of the country. Figure 4 is a NASA TRMM rain rate composite from around 21Z on the 9th. Average rain rates were as high as .6”/hour within rain band moving into Southern California.

- Figure 1. DMSP SSMI Precipitable Water Composite from 05Z Jan 9.

- Figure 2. GOES-10 Water Vapor Image from 0530Z Jan 9.

- Figure 3. DMSP SSMI Precipitable Water Composite from 18Z Jan 9.

- Figure 4. NASA TRMM Rain Rate Composite from 21Z Jan 9.

- With satellite data indicating the presence of a well defined subtropical shortwave which was still in the process of amplifying and the large amount of deep tropical moisture being drawn northward toward Southern California, a short term forecast was made emphasizing the potential of excessive rainfall. The following is an example of one of the Satellite Precipitation Estimates (SPENES) messages issued by the Satellite Analysis Branch (SAB) of the National Environmental Satellite Data and Information Service (NESDIS) via the Advanced Weather Interactive Processing System (AWIPS). The message, which is directed to all affected National Weather Service Forecast Offices and River Forecast Centers, focuses primarily on interpretation of satellite data for short term forecasting purposes. The Satellite Analysis Branch of NESDIS is collocated with the Hydrometeorological Prediction Center (HPC) of the National Centers of Environmental Prediction (NCEP). HPC specializes in quantitative precipitation forecasts through a detailed analysis of numerical forecast guidance. SAB briefs HPC concerning satellite data and coordinates with HPC prior to issuing SPENES messages which contain a short term forecast.

- A partial listing of rainfall totals for the 4 day event is listed below, including a max storm total of over 31” in the mountains just east of Los Angeles.  The resulting rains also triggered a deadly mudslide on Monday, January 10, in La Conchita, California.

- In this case, some of the numerical forecast guidance in advance was pointing toward a significant multi-day rain event for California, but the details concerning the evolution of the heaviest portion of the event were still in question. The purpose of the SPENES message was to focus on more of the details within the short range by blending current observations along with GOES analysis tools and trends with the most recent microwave data. Through careful analysis and interpretation of these data sets, an outlook was prepared which alerted National Weather Service Forecasters in Southern California for a high probability of flooding throughout the day on Sunday, January, 9.  Prior and subsequent SPENES messages were issued which also focused on satellite based short term rainfall trends concerning the evolution of the multi-day excessive rainfall event across Southern California.  SPENES messages and other NESDIS precipitation products can be found at the following internet address: _[http://](http://www.ssd.noaa.gov/PS/PCPN/precip.html)__[www.ssd.noaa.gov/PS/PCPN/precip.html](http://www.ssd.noaa.gov/PS/PCPN/precip.html)_

- Strong Subtropical Shortwave with Darkening Noted Along Western and Southern Portions is a Good Indication of Trof Still Amplifying.

- Slightly Greater than 1” Precipitable Water Values

- Precipitable Water Values Seen in Later SSMI Pass are Now up to 1.3”

- TRMM Areal Average Rain Rates as High as .6”/hr were Depicted Within Rain Band Approaching Southern California.

- Approximately 10 days prior to the extreme southern California heavy rainfall event, another excessive rainfall event affected the southwestern US.  While this one also brought heavy rains to the same portion of southern California hit hard by the January storm, the focus for the heaviest rains from this system was directed across extreme southern California, southern Nevada, and northern Arizona.  The subsequent microwave (Figures A and D) and GOES (Figures B and C) images show the presence of a well defined subtropical jet and moisture plume with strong subtropical shortwave.  In Figure B, GOES High Density upper level wind speed contours are plotted on a Water Vapor image with greater than 130kts are analyzed in the core of the subtropical jet aimed at Arizona. The approach of this speed max along with the subtropical shortwave helps to create larger scale lift and increasing upper level diffluence across the Southwest.  The SSMI image shown (Figure A) depicts the highest moisture being directed from the subtropics into Arizona while the NASA TRMM pass (Figure D) from a few hours later shows a narrow band of heavy rain stretching from far southern California across southern Nevada and northwestern Arizona.  The GOES IR image (Figure C) and the NASA TRMM pass also indicate a larger area of heavy rain associated with the strong subtropical shortwave approaching coastal southern California.  Trends outlined in the SPENES message issued close to 10Z on December 29, 2004 stated the active rain band affecting area from far southern California to northwestern Arizona had remained nearly stationary while the larger primary heavy rain area to the west moved into southern California.  Trends also pointed to the slight northwestward shift in the axis of the deep tropical moisture plume.  All of these factors were indicators of the evolution of an excessive rain event for far southern California, southern Nevada, and northern Arizona.

- Figure A. DMSP SSMI Precipitable Water Composite From 0430Z Dec 29.

- Figure B. GOES Water Vapor image from 0330Z Dec 29 with plot of GOES High Density Upper Level Isotachs.

- Figure C. GOES IR image from 0400Z Dec 29.

- Figure D. NASA TRMM Rain Rate Composite from 09Z Dec 29.

- The statement below from the Flagstaff Arizona Forecast Office lists impressive precipitation totals for a 2 week period ending on January 11, 2005.

**CONCLUSION**

- These examples showed how a careful analysis of certain types satellite derived data and observations can be especially helpful in preparing short term discussions concerning the potential for heavy rainfall and flooding for weather systems approaching the West Coast of the United States.  Trends seen in microwave and GOES satellite data are particularly important as the system approaches the coast to further define the location and intensity of the event.  In these types of events though it is likely that the final factor in determining the exact location of heavy rainfall will be where the lower level flow component sets up perpendicular to the local terrain.

- Greater than 1” PW Plume Directed into the Southwest

- Well Defined Subtropical Jet with GOES High Density Wind Analysis Showing Greater than 130kt Speed Max

- Vigorous Disturbance with Batch of Enhanced Cloud Tops Indicating Moderate to Heavy Rain Moving into Southern California

- Band of Moderate to Heavy Rain in Advance of Strong Disturbance Remains Across Far Southern California, Southern Nevada, and Northwestern Arizona

- Impressive Areal Average Rain Rates of over .8”/hr are Shown Moving into Southern California

- Band with Aeral Average Rain Rates Locally Over .5”/hr Precedes Primary Disturbance Moving into Southern California