Severe Thunderstorm Warning 85, NWS El Paso, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EL PASO TX/SANTA TERESA NM
215 PM MDT WED OCT 20 2010

.SYNOPSIS...
A SLOW MOVING UPPER LOW WILL APPROACH THE AREA TONIGHT AND TRACK
ACROSS THE NEW MEXICO THURSDAY. INCREASED MOISTURE HAS MOVED INTO
THE REGION IN THE DEEP SOUTHERLY FLOW AHEAD OF THIS STRONG STORM
SYSTEM. THIS EVENING AND OVERNIGHT DYNAMICS AND MOISTURE WILL
COMBINE TO SUPPORT THE GENERATION OF SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS AREA WIDE. SOME OF THESE STORMS WILL LIKELY
BECOME SEVERE WITH THE POTENTIAL FOR STRONG DAMAGING WINDS AND
LARGE HAIL. FROM THE RIO GRANDE VALLEY EASTWARD A TORNADO WILL BE
POSSIBLE. STORM ACTIVITY WILL CONTINUE INTO THURSDAY...BUT BE
DIMINISHED IN AREA COVERAGE. BEHIND THE UPPER LOW A WESTERLY FLOW
PATTERN WILL BRING DRY AIR BACK TO THE BORDERLAND FRIDAY. A
TRAILING TROUGH WILL PASS THROUGH LATE FRIDAY AND COULD PRODUCE A
FEW SHOWERS OVER THE AREA MOUNTAINS. ANOTHER TROUGH CLIPS THE
SACRAMENTO MOUNTAINS FOR ANOTHER BRIEF SHOT AT STORMS ON SUNDAY.
GENERALLY THE ARE WILL BE DRY AFTER THURSDAY WITH COOLER TEMPERATURES.

&&

.DISCUSSION...
A LOT OF THINGS TO LOOK AT FOR THE SHORT TERM...THE 0-24 HR
PERIOD. FIRST OFF...EXPECTING A BOUT OF SEVERE WEATHER TONIGHT. A
DEEP AND STRONG UPPER LOW IS CENTERED OVER YUMA THIS AFTERNOON. A
LOW LEVEL EAST PUSH OVERNIGHT AND DEEP SOUTHERLY WINDS AHEAD OF
THE LOW HAVE INCREASED MOISTURE LEVELS OVER THE CWFA. THE 12Z EPZ
SOUNDING SHOWED 0.68" PWAT...BUT GOTTA ASSUME THE CURRENT AMOUNT
IS HIGHER...AND PROG SOUNDINGS DO SHOW 0.8-0.9" TONIGHT. DYNAMICS
GET IMPRESSIVE THIS EVENING AS THE LOW SLOWLY MOVES TOWARD THE REGION.
ALOFT WE HAVE DIVERGENCE ALOFT...PVA...AN 80KT+ LF JET QUAD...AND
COOLING H5 TEMPS AHEAD OF THE LOW. THESE INGREDIENTS LOOK TO BEGIN
INFLUENCING THE AREA OVER THE CWFA ABOUT 00Z THIS EVENING. AT THE
SURFACE WE HAVE HIGHER DEWPOINTS EAST AND A NICELY DEFINED
CONVERGENCE ZONE IN A TROUGH LINED UP N-S THROUGH THE RIO GRANDE
VALLEY. THIS CONVERGENCE LINE IS HUNG OVER THE WESTERN EXTEND OF
THE RIO GRANDE RIVER VALLEY THIS AFTERNOON AND WILL SHIFT EAST TO
OTERO/HUDSPETH LATE TONIGHT. ALL THE ABOVE FACTORS SHOULD LINE UP
TO ALLOW FOR SCT-NUM SHOWERS AND THUNDERSTORMS TO DEVELOP. WE
EXPECT THE FIRST CELLS TO FORM MID AFTERNOON...WITH INCREASING
COVERAGE LATE AFTERNOON/EARLY EVENING. THE BEST STORM POTENTIAL
LOOKS TO OCCUR BETWEEN 8PM TONIGHT AND 4 AM IN THE MORNING.

THE SEVERE WEATHER THREATS APPEAR TO BE AS SUCH. WEST OF THE RIO
GRANDE THE VERTICAL WIND PROFILE (VWP) AND INSTABILITY SHOW
POTENTIAL FOR STRONG GUSTY WINDS AND LARGE HAIL. EAST OF THE RIO
GRANDE THE VWP SHOWS TURNING WITH HEIGHT AND THUS A SLIGHT RISK OF
TORNADO DEVELOPMENT IN ADDITION TO THE LARGE HAIL AND WIND POTENTIAL.
AS THE PACIFIC FRONT. AS THE SURFACE TROUGH SHIFTS EAST AFTER
MIDNIGHT THE TORNADO THREAT WILL DIMINISH FROM THE RIO GRANDE
VALLEY EASTWARD FROM ABOUT MIDNIGHT TO 4AM.

BOTH THE GFS AND NAM SHOW A VERY SLOW PROGRESSION WITH THE LOW
LIFTING AND TRACKING ACROSS NEW MEXICO. A PACIFIC SURFACE FRONT
WILL ALSO PUSH ACROSS THE REGION TURNING WINDS WEST AND BEGINNING
SOME SURFACE DRYING. A DRY SLOT APPEARS TO MOVE ACROSS THE REGION
TOMORROW MORNING...SCOURING OUT THE PCPN WITH SOME LOW CLOUDS AND
LIGHT SHOWERS LINGERING. THE UPPER LOW THEN TRACKS INTO AND ACROSS
THE CWFA MID-DAY THROUGH THE EVENING HOURS. WE COULD SEE A SMALL
INCREASE IN SHOWERS AND STORMS... MAINLY NORTH ZONES. ALTHOUGH NOT
AS IMPRESSIVE...WE COULD SEE SOME ISOLATED PULSE SEVERE STORMS
AGAIN. THE STORM SYSTEM PICKS UP SPEED AND EXITS RAPIDLY IN THE
EVENING.

FRIDAY WILL BE COOL AND DRY WITH DEEP WESTERLY FLOW IN LEE OF THE
DEPARTED SYSTEM. SATURDAY A TRAILING TROUGH IN THE PROGRESSIVE
FLOW ALOFT WILL QUICKLY TRACK ACROSS THE CWFA. THE NAM KEEPS IT
SHALLOW AND DRY WHILE THE GFS IS A BIT SHARPER AND ALLOWS FOR SOME
MOUNTAIN STORM DEVELOPMENT LATE FRIDAY. MOST AREAS WILL REMAIN DRY
AND UNAFFECTED. A SECOND TROUGH IS PROGED TO DROP IN AND CLIP THE
NE PORTION OF OUR FORECAST AREA SUNDAY. THUS ISOLATED PCPN IS
AGAIN POSSIBLE FOR THE SACS SUNDAY AFTERNOON...BUT ALL OTHER
LOCATIONS SHOULD REMAIN DRY.

BEYOND SUNDAY THE FLOW FLATTENS WITH THE PATTERN GENERALLY ZONAL
ACROSS THE SOUTHERN TIER OF THE U.S. A BROAD TROUGH WILL PASS WELL
NORTH BUT WE SHOULDN'T BE AFFECTED. TEMPERATURES SHOULD WARM BACK
TO SEASONAL WITH DRY CONDITIONS AND GENERALLY CLEAR SKIES.

14 - BIRD

&&

.AVIATION...VALID 21/00Z-22/00Z...
LOW PRESSURE ALOFT CROSSING THE AREA WILL TRIGGER SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS TONIGHT AND TOMORROW. EXPECT
AREAS OF 1-3SM SHRA/TSRAGR BKN-OVC030-060. SOME STORMS COULD BE
SEVERE...ESPECIALLY EAST OF THE RIO GRANDE.

21 - PARK

&&

.FIRE WEATHER...
SOUTH TO SOUTHEAST WINDS ARE BRINGING INCREASING LOW LEVEL MOISTURE
TO THE AREA. THIS WILL PROVIDE THE NECESSARY FUEL FOR SHOWERS AND
THUNDERSTORMS TONIGHT AND THURSDAY. AN UPPER LEVEL LOW MOVING SLOWLY
EASTWARD ACROSS ARIZONA AND INTO NEW MEXICO WILL PROVIDE THE TRIGGER
FOR SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TONIGHT AND
TOMORROW. SOME STORMS COULD BE SEVERE THIS EVENING INTO TONIGHT WITH
STRONG WINDS...LARGE HAIL AND HEAVY RAIN. TURNING COOLER THURSDAY
WITH ADDITIONAL SHOWERS AND THUNDERSTORMS AS THAT UPPER LEVEL LOW
AND AN ASSOCIATED PACIFIC COLD FRONT MOVE THROUGH. TEMPERATURES WILL
BE SEVERAL DEGREES BELOW NORMAL FRIDAY THROUGH THE WEEKEND. WEAK
DISTURBANCES WILL BRING A SLIGHT CHANCE OF SHOWERS FRIDAY NIGHT AND
AGAIN SUNDAY...MAINLY OVER AREA MOUNTAINS.

21 - PARK

&&

.PRELIMINARY POINT TEMPS/POPS...
EL PASO                 54  73  47  72  48 /  60  30  10   0   0
SIERRA BLANCA TX        52  74  44  72  45 /  60  20  10   0   0
LAS CRUCES              51  72  44  70  45 /  60  30  10   0   0
ALAMOGORDO              49  70  44  70  45 /  60  40  30  10   0
CLOUDCROFT              40  52  31  50  30 /  70  50  30  10  10
TRUTH OR CONSEQUENCES   50  69  40  70  44 /  60  40  10   0   0
SILVER CITY             44  61  36  62  36 /  60  40  10  10  10
DEMING                  49  68  41  69  42 /  50  30  10   0   0
LORDSBURG               48  67  41  69  41 /  50  40  10   0   0

&&

.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...NONE.
TX...NONE.
&&

14/21

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