Flash Flood Warning 20, NWS El Paso, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EL PASO TX/SANTA TERESA NM
226 PM MDT SAT JUL 24 2010

.SYNOPSIS...
ABUNDANT MOISTURE ACROSS THE REGION...IN COMBINATION WITH WEAK
UPPER LEVEL WEATHER DISTURBANCES...WILL SUPPORT THE DEVELOPMENT
OF SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS THROUGH SUNDAY
AFTERNOON. SOME OF THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE
TORRENTIAL RAINFALL THAT COULD LEAD TO FLASH FLOODING. SOME DRYING
OF THE AIRMASS OVER THE REGION WILL BEGIN DURING THE EARLY PART OF
THE UPCOMING WORK WEEK...BUT ENOUGH MOISTURE WILL REMAIN IN PLACE
TO SUPPORT ISOLATED SHOWER AND THUNDERSTORM DEVELOPMENT THE
REMAINDER OF THE WEEK.

&&

.DISCUSSION...
SHOWER AND THUNDERSTORM DEVELOPMENT HAS FAVORED THE EASTERN CWA SO
FAR THIS AFTERNOON...AND THIS IS VERY MUCH IN LINE WITH THE 1200
UTC NAM RUN. THE ABUNDANT MOISTURE ACROSS THE REGION...IN CONCERT
WITH SUPPORT FROM NEW AND REMNANT BOUNDARIES AS WELL AS FROM UPPER
LEVEL DISTURBANCES WILL KEEP A RISK OF HEAVY RAIN A POSSIBILITY
FOR ALL FORECAST AREAS. PRECIPITABLE WATER VALUES WILL REMAIN
UNSEASONABLY HIGH THROUGH SUNDAY...WITH UPPER AIR PROFILES THAT
SUPPORT VERY EFFICIENT RAIN RATES.

MODEL DISCREPANCIES RELATIVE TO QPF AND POPS RESULTED IN A
PROBLEMATIC FORECAST. THE BIGGEST SEPARATION WAS APPARENT TONIGHT
WITH THE NAM PRODUCING A MUCH MORE CONSERVATIVE FORECAST IN TERMS
OF BOTH POPS AND QPF. MODELS ARE A BIT MORE IN LINE ON SUNDAY...WITH
ENOUGH JUSTIFICATION TO SUPPORT EXTENDING THE FLASH FLOOD WATCH
THROUGH SUNDAY AFTERNOON. WE EXTENDED THE WATCH APPROPRIATELY AND
ALSO BUMPED UP POPS INTO SUNDAY EVENING.

BOTH MODELS ARE CONSISTENT IN INTRODUCING SOME DRYING TO THE AREA
DURING THE EARLY PART OF NEXT WEEK. SUBSIDENCE ASSOCIATED WITH
UPPER LEVEL CYCLONIC FEATURE CURRENTLY OVER TEXAS WILL SERVE TO
QUIET THE WEATHER DOWN AT THAT TIME AS IT SLOWLY MOVES WESTWARD. ON
THE OTHER HAND...THIS VERY SAME FEATURE MAY AID IN SUPPORTING AN
UPTICK IN ACTIVITY TOWARD THE MIDDLE AND END OF THE WEEK. HAVE
GONE WITH A PERSISTENCE FORECAST FOR NOW FOR THE MIDDLE AND LATTER
PORTION OF THE WEEK PENDING ADDITIONAL GUIDANCE.

&&

.AVIATION...VALID 25/00Z-26/00Z
WEAK BUT RATHER BROAD UPPER LEVEL LOW MOVING SLOWLY NE OVER
NM...WILL CONTINUE TO DRAW SUB-TROPICAL STREAM OF MOIST UNSTABLE AIR
NORTHWARD OVER E-CENTRAL NEW MEXICO EARLY THIS EVENING.  THIS WILL
MEAN SCT +TSRAGS/VSBY 1-3SM/TOPS 400 AND SFC WINDS VRB 35G50KTS
AREA-WIDE...WITH ACTIVITY CONCENTRATED E OF RIO GRANDE LATER TODAY.
ANOTHER IN A SERIES OF TROPICAL WAVES APPROACHING FROM THE
GULF...WILL SHOVE THIS MOISTURE BACK WESTWARD TOWARDS AZ BORDER
SUNDAY.  AS A RESULT...LOOK FOR SCT-NMRS +TSRAGS/TOPS 450...SIMILAR
VSBY/WINDS AND CIGS BKN030-050 AND BKN-OVC100-160 WITH STORMS. GIVEN
AMPLE MOISTURE AND ATTENDANT LIFT WITH LOW...DEVELOPMENT OF LARGER
THUNDERSTORM COMPLEX WITH LITTLE OR NO MOVEMENT IS NOT OUT OF REALM
OF POSSIBILITIES. INDIVIDUAL CELLS WILL GENERALLY TRACK 10-15 MPH
FROM SSE-NNW.

&&

.FIRE WEATHER...
WEAK BUT RATHER BROAD UPPER LEVEL LOW MOVING SLOWLY NE OVER
NM...WILL CONTINUE TO DRAW SUB-TROPICAL STREAM OF MOIST UNSTABLE AIR
NORTHWARD OVER E-CENTRAL NEW MEXICO EARLY THIS EVENING. WITH SUMMER
HEATING...THIS WILL MEAN CONTINUED SCATTERED SHOWERS AND STORMS
AREA-WIDE...WITH ACTIVITY EXPECTED TO CONCENTRATE EAST OF THE RIO
GRANDE THROUGH EARLY THIS EVENING.  ANOTHER IN A SERIES OF
TROPICAL WAVES APPROACHING FROM THE GULF...WILL SEND THIS MOISTURE
BACK TOWARDS THE ARIZONA BORDER SUNDAY.  THIS WILL INCREASE STORM
COVERAGE FOR ALL ZONES.  APPROACH OF WAVE AND SUBTLE INCREASE IN
SOUTHEAST FLOW ALOFT WILL WORK TO SEND MOISTURE STREAM FURTHER
WESTWARD OUT OF THE AREA EARLY NEXT WEEK...WHERE WE MAY ACTUALLY SEE
A DOWN-TURN IN SHOWER/STORM COVERAGE.  BY MID WEEK...WAVE IS
EXPECTED TO AGAIN RAMP-UP ACTIVITY.  MIN RH WILL RANGE GENERALLY
FROM 30%-40% IN THE NM BOOTHEEL...40%-50% ACROSS OTHER LOWLAND
AREAS...AND OVER 50% GENERALLY ABOVE 7000 FT.  HAINES INDICIES OF
2-3 WILL BE FOUND FOR MOST AREAS THIS WEEKEND...WITH 4 EXPECTED
TODAY FOR THE NEW MEXICO BOOTHEEL. VALUES OF 2-3 ANTICIPATED ALL
AREAS NEXT WEEK.  FREQUENT CLOUD TO GROUND LIGHTNING...VERY HEAVY
RAINFALL AND GUSTY OUTFLOW WINDS REMAIN THE SIGNIFICANT THREATS WITH
STORMS THROUGH THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
EL PASO                 69  87  69  90  70 /  50  40  30  20  20
SIERRA BLANCA TX        63  82  64  84  65 /  50  30  30  20  20
LAS CRUCES              66  86  66  89  67 /  50  50  30  20  20
ALAMOGORDO              62  87  63  89  64 /  50  50  30  20  20
CLOUDCROFT              47  66  47  69  48 /  60  50  40  30  20
TRUTH OR CONSEQUENCES   62  85  63  88  64 /  60  50  30  20  20
SILVER CITY             55  78  55  80  56 /  60  60  40  30  30
DEMING                  63  85  63  88  64 /  50  50  40  20  20
LORDSBURG               62  87  64  90  65 /  50  50  40  30  30

&&

.EPZ WATCHES/WARNINGS/ADVISORIES...

NM...FLASH FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR NMZ022>025-
     030>032.
TX...FLASH FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR TXZ055-056.

&&

00/22

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE EL PASO TX/SANTA TERESA NM
148 PM MDT SAT JUL 24 2010

NMZ022>025-030>032-TXZ055-056-251730-
SOUTHWEST MOUNTAINS/LOWER GILA REGION-SIERRA COUNTY LAKES REGION-
TULAROSA BASIN/SOUTHERN DESERT-SOUTHERN SACRAMENTO MOUNTAINS-
SOUTHWEST DESERT/BOOTHEEL-SOUTHWEST DESERT/MIMBRES BASIN-
SOUTHERN DESERT-EL PASO-HUDSPETH-
148 PM MDT SAT JUL 24 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
NEW MEXICO...SOUTHWEST NEW MEXICO AND SOUTHWEST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A FLASH FLOOD WATCH IS IN EFFECT FOR ALL OF SOUTH CENTRAL AND
SOUTHWEST NEW MEXICO AS WELL AS SOUTHWEST TEXAS. PLEASE REFER TO
THE LATEST FLOOD WATCH STATEMENT FROM THE NATIONAL WEATHER SERVICE
IN EL PASO FOR DETAILS.

SHOWERS AND THUNDERSTORMS THAT FORM TODAY WILL HAVE THE POTENTIAL
TO PRODUCE TORRENTIAL RAINFALL WITH RAINFALL RATES AS HIGH AS TWO
INCHES PER HOUR...POSSIBLE FLOODING...SMALL HAIL...WINDS UP TO 50
MPH...AND DEADLY LIGHTNING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A FLASH FLOOD WATCH IS IN EFFECT FOR ALL OF SOUTH CENTRAL AND
SOUTHWEST NEW MEXICO AS WELL AS SOUTHWEST TEXAS THROUGH SUNDAY
AFTERNOON. PLEASE REFER TO THE LATEST FLOOD WATCH STATEMENT FROM
THE NATIONAL WEATHER SERVICE IN EL PASO FOR DETAILS.

ABUNDANT MOISTURE IS EXPECTED TO REMAIN ACROSS THE REGION ON
SUNDAY. THIS MOISTURE WILL LEAD ONCE AGAIN TO THE DEVELOPMENT OF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. MOISTURE WILL
DECREASE DURING THE EARLY PART OF THE WEEK AS HIGH PRESSURE BUILDS
IN OVER THE SOUTHWEST. A RETURN TO WETTER CONDITIONS IS POSSIBLE
LATER NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.
SPOTTERS ARE URGED TO REPORT SEVERE WEATHER CONDITIONS TO THE
NATIONAL WEATHER SERVICE VIA OUR TOLL FREE LINE.