825
FXUS64 KEPZ 211248
AFDEPZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EL PASO TX/SANTA TERESA NM
648 AM MDT MON SEP 21 2026
..NEW AVIATION, FIRE WEATHER
KEY MESSAGES
UPDATED AT 1159 PM MDT SUN SEP 20 2026
- QUIET AND WARM WEATHER WILL CONTINUE FOR THE NEXT 36 HOURS OR
SO.
- AN EARLY SEASON BACK DOOR COLD FRONT WILL INTERACT WITH A LATE
SEASON MONSOON MOISTURE SURGE AND BRING WIDESPREAD SHOWERS AND
THUNDERSTORMS TO THE AREA TUESDAY AFTERNOON THROUGH WEDNESDAY
AFTERNOON. LOCALIZED FLASH FLOODING WILL BE A RISK OVER A LARGE
PORTION OF THE AREA.
- THE MAIN CONCERN IS THAT A NARROW AXIS OF MORE PERSISTENT
THUNDERSTORMS AND PARTICULARLY HEAVY RAINFALL AMOUNTS WILL SET
UP SOMEWHERE IN SOUTH-CENTRAL NEW MEXICO OR FAR WEST TEXAS,
WITH HIGHER IMPACT FLOODING TUESDAY NIGHT INTO WEDNESDAY
MORNING. THIS COULD INCLUDE THE MESILLA VALLEY AND EL PASO
AREA, THOUGH THERE IS CONSIDERABLE UNCERTAINTY IN EXACTLY WHERE
THIS NARROW AXIS WILL SET UP.
DISCUSSION
ISSUED AT 1137 PM MDT SUN SEP 20 2026
FAIRLY QUIET THROUGH EARLY TUESDAY, WITH JUST A SLIGHT CHANCE OF A
FEW SHOWERS AND THUNDERSTORMS IN THE BOOTHEEL ON MONDAY,
SPREADING A LITTLE NORTH AND EAST MONDAY NIGHT. BUT THE PAIRING OF
AN EARLY-SEASON BACK DOOR COLD FRONT AND A LATE-SEASON MONSOONAL
MOISTURE SURGE WILL RESULT IN SOME BIG CHANGES TUESDAY THROUGH
THURSDAY.
THE FIRST PIECE OF THE PUZZLE WILL BE A BACKDOOR COLD FRONT
PUSHING INTO THE SACRAMENTO MOUNTAINS BY AROUND MIDNIGHT MONDAY
NIGHT/TUESDAY MORNING, AND REACHING THE RIO GRANDE BY DAWN. NBM
TRIED RAMPING UP HIGHER POPS IN THE SACS A LITTLE TOO EARLY. IT
LOOKS LIKE FAIRLY SHALLOW MOISTURE WILL RESULT IN FOG AND LOW
STRATUS ADVECTING UP TO THE MAIN RIDGELINE IN THE SACRAMENTOS
MONDAY NIGHT INTO TUESDAY MORNING, WITH THE LOW CLOUDS SHAKING
OUT SOME DRIZZLE RATHER THAN STEADY SHOWERS OR CONVECTION. THE LOW
CLOUDS AND FOG WILL LIFT BY MID TO LATE MORNING TUESDAY.
MEANWHILE, A CLOSED UPPER LOW OVER SOUTHERN CALIFORNIA WILL WEAKEN
INTO AN OPEN TROUGH BY TUESDAY MORNING, WHILE A STALLED OUT
SUBTROPICAL RIDGE OVER TEXAS BLOCKS ITS PROGRESSION. THIS WILL
CAUSE THE UPPER LEVEL PATTERN TO AMPLIFY, WITH SW FLOW ALOFT
BACKING SLIGHTLY AND PULLING UP DEEP SUBTROPICAL MOISTURE UP THE
SIERRA MADRES AND INTO SOUTHERN NEW MEXICO. THAT'S THE SECOND
PIECE OF THE PUZZLE.
THE THIRD PIECE WILL BE A STRONG SUBTROPICAL JET OVER SOUTHERN
BAJA CALIFORNIA MONDAY NIGHT, WHICH WILL HELP MAINTAIN INTENSE
THUNDERSTORMS OVER THE SIERRA MADRES IN SW CHIHUAHUA. A
CONVECTIVELY-INDUCED SHORTWAVE TROUGH OR WEAK CLOSED UPPER LOW
WILL THEN ROLL NORTH, ALONG WITH THE SUBTROPICAL JET AND A BROAD
REGION OF UPPER LEVEL DIFFLUENCE. THIS SHORTWAVE TROUGH (THE
FOURTH PIECE OF THE PUZZLE) WILL HELP TRIGGER STRONGER
THUNDERSTORMS TUESDAY AFTERNOON. ENHANCED MID LEVEL FLOW WILL
PROVIDE 20-30 KNOTS OF 0-6KM SHEAR, ENOUGH FOR MORE ORGANIZED,
LONGER-LIVED THUNDERSTORMS. THE BROAD UPPER DIVERGENCE WILL
PERSIST THROUGH TUESDAY NIGHT, WHILE A TRAILING VORT LOBE
ASSOCIATED WITH THE SHORTWAVE TROUGH PIVOTS INTO SOUTH-CENTRAL NEW
MEXICO. THIS UPPER LEVEL SUPPORT WILL HELP MAINTAIN THUNDERSTORM
DEVELOPMENT THROUGH THE NIGHT AND INTO WEDNESDAY MORNING.
THE RESULT WILL BE A FAIRLY WIDESPREAD AREA OF "DECENT" MODERATE
RAINFALL, WITH THE USUAL SMALLER POCKETS OF HEAVY RAINFALL, AIDED
BY A VERY MOIST PROFILE (HIGHLY EFFICIENT ARM RAIN PROCESSES), AND
UPPER LEVEL STEERING FLOW THAT FAVORS TRAINING. HOWEVER...AS THE
EVENT STARTS COMING INTO RANGE, IT APPEARS THERE IS A HIGH
POTENTIAL THAT SOMEWHERE IN THIS WHOLE MESS A MORE PERSISTENT AREA
OF TRAINING THUNDERSTORMS WILL DEVELOP TUESDAY NIGHT INTO
WEDNESDAY MORNING, WITH MAX QPF POTENTIAL EXCEEDING 3-4 INCHES IN
A 6-12 HOUR PERIOD.
THE BACKDOOR COLD FRONT WILL STALL OUT ALONG THE RIO GRANDE
TUESDAY AFTERNOON, WITH INTENSE MOISTURE CONVERGENCE DEVELOPING
ALONG THIS BOUNDARY DURING THE EVENING HOURS. THE GFS SHOWS A
MID-LEVEL JET STREAK OF AROUND 40 KNOTS DEVELOPING AHEAD OF THE
TRAILING VORT LOBE, WITH A CONCENTRATED AREA OF STRONG THETA-E
ADVECTION IN THE 700-500 MB LAYER. WHERE THIS ALIGNS WITH THE
STRONG LOW LEVEL MOISTURE CONVERGENCE ALONG THE STALLED OUT FRONT,
IS LIKELY WHERE THE AXIS OF HEAVIEST PRECIP WILL OCCUR.
RECENT MODEL RUNS, INCLUDING THE 12Z AND 18Z ECMWF, 00Z GFS, AND
00Z RRFS, AND THE LAST FEW HOURS OF THE 00Z HRRR ARE PUTTING THIS
FOCUS AREA RIGHT OVER THE MESILLA VALLEY AND EL PASO TUESDAY NIGHT
INTO WEDNESDAY MORNING.
HOWEVER, IT IS IMPORTANT TO POINT OUT THE THE NBM, AND THE 18Z GFS
AND ECMWF ENSEMBLES SHOW THERE IS SIGNIFICANT SPREAD IN WHERE THIS
AREA COULD SET UP. FOR EXAMPLE, THE NBM MEAN QPF IS FAIRLY USELESS
AT THE MOMENT, AS IT AVERAGES OUT QPF MAXES SHOWING UP IN A WIDE
RANGE OF PLACES. THIS ALSO BECOMES APPARENT WHEN LOOKING AT THE
NBM QPF MAX NUMBERS, WHICH PLACE THE POTENTIAL FOR 3-5 INCHES
OVER WIDE AREA.
THE "WIDE AREA" IS ANYWHERE FROM THE BLACK RANGE DOWN TO LUNA
COUNTY, EAST TO THE TULAROSA BASIN AND WESTERN HUDSPETH COUNTY.
SO, NOT THE ENTIRE CWA AT LEAST! A FLOOD WATCH HAS BEEN ISSUED FOR
THIS SAME AREA, STARTING TUESDAY AFTERNOON (AS ISOLATED
THUNDERSTORMS FIRST FIRE UP) INTO WEDNESDAY EVENING. THE MOST
CRITICAL PERIOD LOOKS TO BE AROUND 3 PM TUESDAY THROUGH MIDDAY
WEDNESDAY. THIS COULD BE ONE OF THOSE UNUSUAL SITUATIONS WHERE
HEAVY RAIN IS ONGOING AT DAY BREAK, WHICH COULD RESULT IN IMPACTS
TO THE MORNING COMMUTE WEDNESDAY. (BUT AGAIN, THE NARROW BAND OF
HEAVIEST RAIN COULD SHIFT INTO MORE OPEN DESERT TO THE WEST OR
LESS-POPULATED AREAS TO THE EAST.)
AFTER A SLUG OF RUNOFF PASSED THROUGH, THE RIO GRANDE IS BACK TO
BEING EMPTY IN THE MESILLA AND EL PASO VALLEYS, WHICH IS A BIT OF
FAVORABLE NEWS.
THERE IS ALSO A "SNEAKER RISK" OF ISOLATED SEVERE THUNDERSTORMS
TUESDAY AFTERNOON, ESPECIALLY IN SW NEW MEXICO WHERE BOTH DEEP-
LAYER AND LOW LEVEL SHEAR WILL BE MAXIMIZED.
PRECIP WILL LIKELY SHIFT EAST WEDNESDAY AFTERNOON AND DIMINISH IN
INTENSITY, WITH DRY PERIODS LIKELY MOVING INTO SW NEW MEXICO AND
THE MESILLA VALLEY. ADDITIONAL HEAVY RAINFALL IS POSSIBLE ON
THURSDAY, BUT MODELS HAVE CONTINUED TO TREND EASTWARD WITH THE
HEAVIEST RAINFALL, AND MODERATED THE AMOUNTS. EASTERN HUDSPETH
COUNTY, NOT CURRENTLY IN THE WATCH FOR TUE/WED, COULD COME INTO
PLAY ON THURSDAY.
ISOLATED TO SCATTERED SHOWERS AND STORMS LOOK TO LINGER FRIDAY,
BUT WITH SPARSER COVERAGE AND MUCH LOWER RAINFALL AMOUNTS.
NEXT WEEK...A COMPLEX PATTERN WITH TROPICAL CYCLONES OFF THE BAJA
PENINSULA, BUT AN AMPLIFYING RIDGE IS LOOKING LIKE IT WILL KEEP
THE DEEPEST MOISTURE WELL TO OUR WEST, THOUGH SCATTERED
THUNDERSTORMS WILL STILL BE AROUND.
OH, AND WEDNESDAY HIGH TEMPERATURES MAY BE STUCK IN THE 70S OVER A
GOOD PORTION OF THE AREA. 12 TO 18 DEGREES BELOW NORMAL.
AVIATION
(12Z TAFS)
ISSUED AT 647 AM MDT MON SEP 21 2026
VFR CONDITIONS THROUGH THE TAF PERIOD WITH LIGHT WIND SPEEDS AOB
10KT. NO RAIN CHANCES EXPECTED TODAY. HIGH CLOUDS COULD BE SEEN AT
KTCS BUT MORE SOUTHERN TAF SITES SHOULD EXPECT MOSTLY FEW-SCT100.
FIRE WEATHER
ISSUED AT 647 AM MDT MON SEP 21 2026
ONE LAST QUIET DAY WITH HARDLY ANY STORM CHANCES ANYWHERE BEFORE A
STRETCH OF WET DAYS. MIN RHS TODAY WILL BE 16-22% IN THE LOWLANDS
AND 25-40% IN THE MOUNTAINS. GRADUAL INCREASE IN MIN RHS TUESDAY TO
30-40% IN THE LOWLANDS AND 50-70% IN THE MOUNTAINS BUT WEDNESDAY AND
THURSDAY MIN RHS INCREASE TO 50-75% IN THE LOWLANDS AND 80-100% IN
THE MOUNTAINS. SCATTERED TO NUMEROUS STORMS EXPECTED TUESDAY THROUGH
MUCH OF THURSDAY WHERE FLASH FLOODING WILL BE THE PRIMARY CONCERN
ACROSS THE AREA. 20 FOOT WINDS WILL BE LIGHT TODAY AT AROUND 5 MPH
BUT TUESDAY WILL BECOME SLIGHTLY BREEZIER WITH SPEEDS 10-15 MPH OUT
OF THE SOUTHEAST. LIGHT WINDS PERSIST WEDNESDAY AND INTO THE WEEKEND
WITH SPEEDS GENERALLY AROUND 5 MPH.
PRELIMINARY POINT TEMPS/POPS
EL PASO 70 88 64 75 / 0 60 90 90
SIERRA BLANCA 64 85 60 79 / 0 30 80 70
LAS CRUCES 65 85 60 72 / 0 80 90 90
ALAMOGORDO 64 86 60 75 / 0 60 80 100
CLOUDCROFT 48 62 46 54 / 20 80 90 90
TRUTH OR CONSEQUENCES 63 80 60 70 / 0 80 90 90
SILVER CITY 60 77 56 69 / 10 80 80 80
DEMING 65 86 60 74 / 10 70 90 80
LORDSBURG 67 84 62 75 / 20 60 70 70
WEST EL PASO METRO 71 88 64 75 / 0 70 90 90
DELL CITY 65 87 63 79 / 10 30 70 80
FORT HANCOCK 71 93 68 84 / 0 30 80 80
LOMA LINDA 63 81 59 71 / 0 50 90 90
FABENS 69 90 66 79 / 0 60 90 80
SANTA TERESA 68 87 63 73 / 0 80 90 90
WHITE SANDS HQ 69 87 64 73 / 0 80 90 90
JORNADA RANGE 66 85 60 71 / 0 80 90 100
HATCH 66 86 62 73 / 10 80 90 90
COLUMBUS 70 88 65 77 / 10 80 90 80
OROGRANDE 66 85 61 73 / 0 60 90 90
MAYHILL 53 72 52 65 / 20 80 90 100
MESCALERO 53 73 51 65 / 20 80 90 90
TIMBERON 52 72 49 62 / 20 70 90 90
WINSTON 56 72 54 64 / 0 70 90 90
HILLSBORO 63 79 58 70 / 0 80 90 90
SPACEPORT 64 82 58 71 / 0 70 90 100
LAKE ROBERTS 55 74 53 68 / 10 80 80 80
HURLEY 61 79 57 71 / 10 70 80 80
CLIFF 62 82 61 76 / 10 70 70 80
MULE CREEK 61 78 59 73 / 20 60 80 70
FAYWOOD 63 79 59 69 / 10 70 80 80
ANIMAS 67 84 63 77 / 30 70 70 70
HACHITA 66 84 62 75 / 20 60 70 70
ANTELOPE WELLS 66 85 63 79 / 30 60 60 60
CLOVERDALE 63 80 59 76 / 30 60 60 60
EPZ WATCHES/WARNINGS/ADVISORIES
TX...FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR
EASTERN/CENTRAL EL PASO COUNTY-NORTHERN HUDSPETH
HIGHLANDS/HUECO MOUNTAINS-RIO GRANDE VALLEY OF EASTERN EL
PASO/WESTERN HUDSPETH COUNTIES-WESTERN EL PASO COUNTY.
NM...FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR
CENTRAL GRANT COUNTY/SILVER CITY AREA-EAST CENTRAL TULAROSA
BASIN/ALAMOGORDO-EAST SLOPES SACRAMENTO MOUNTAINS BELOW
7500 FEET-EASTERN BLACK RANGE FOOTHILLS-NORTHERN DONA ANA
COUNTY-OTERO MESA-SACRAMENTO MOUNTAINS ABOVE 7500 FEET-
SIERRA COUNTY LAKES-SOUTHEAST TULAROSA BASIN-SOUTHERN DONA
ANA COUNTY/MESILLA VALLEY-SOUTHERN GILA FOOTHILLS/MIMBRES
VALLEY-SOUTHERN GILA REGION HIGHLANDS/BLACK RANGE-SOUTHWEST
DESERT/MIMBRES BASIN-WEST CENTRAL TULAROSA BASIN/WHITE
SANDS-WEST SLOPES SACRAMENTO MOUNTAINS BELOW 7500 FEET.
FORECASTER...37-SLUSHER
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