Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 260400
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
900 PM MST SAT APR 25 2015

.SYNOPSIS...EXPECT SCATTERED TO NUMEROUS SHOWERS AND A SLIGHT
CHANCE OF THUNDERSTORMS INTO SUNDAY AS A STRONG LOW PRESSURE SYSTEM
MOVES ACROSS THE FOUR CORNERS REGION. COOLER TEMPERATURES WILL ALSO
OCCUR SUNDAY. A FEW SHOWERS MAY OCCUR ACROSS THE WHITE MOUNTAINS
MONDAY AND TUESDAY. THEREAFTER...DRY CONDITIONS WITH WELL ABOVE
NORMAL DAYTIME TEMPERATURES WILL PREVAIL WEDNESDAY THROUGH SATURDAY.

&&

.DISCUSSION...KEMX WSR-88D DETECTED ISOLATED 35-45 DBZ ECHOES ACROSS
FAR WRN PIMA COUNTY NE OF AJO AT 0355Z. SCATTERED MOSTLY LESS THAN
30 DBZ ECHOES EXTENDED FROM TUCSON NWD ACROSS SERN PINAL/FAR WRN
GRAHAM COUNTIES. CELL MOVEMENT WAS GENERALLY TO THE NORTHEAST AROUND
20 KTS.

A DEEPENING UPPER TROUGH EXTENDED FROM THE SWRN CONUS INTO THE
PACIFIC NW THIS EVENING. A 554 DM LOW PRESSURE CENTER IS PROGGED VIA
THE 26/00Z NAM AND 26/18Z GFS TO BE OVER NERN ARIZONA AROUND
DAYBREAK SUN. HAVE NOTED THAT THE 26/00Z NAM INCREASED POPS FAIRLY
SUBSTANTIALLY FOR THE REST OF TONIGHT...ESPECIALLY FROM TUCSON NWD...
VERSUS PREVIOUS SOLUTIONS. HAVE ALSO NOTED THAT SEVERAL RUC HRRR
SOLUTIONS HAVE GENERALLY TRENDED HIGHER WITH PROGGED LIQUID RAIN
AMOUNTS THRU 12Z-15Z SUNDAY. ACCORDING TO THE 26/02Z HRRR...THE
TIMING FOR THE BEST CHANCE OF MEASURABLE RAINFALL FOR THE
TUCSON METRO AREA WILL OCCUR FROM 05Z-12Z SUNDAY OR SO.

BASED ON RADAR TRENDS AS WELL AS THE MOST RECENT RUC/NAM SOLUTIONS...
HAVE INCREASED POPS FOR THE REST OF TONIGHT...PARTICULARLY FROM
TUCSON NWD ACROSS SERN PINAL/WRN GRAHAM COUNTIES. HAVE ALSO ADDED A
SLIGHT CHANCE OF THUNDERSTORMS ACROSS MUCH OF THE AREA THE REST OF
TONIGHT. THE BULK OF THE PRECIPITATION SUNDAY SHOULD OCCUR NE OF
TUCSON...OR ACROSS NRN GREENLEE/GRAHAM COUNTIES. HAVE ALSO ADDED A
SLIGHT CHANCE OF THUNDERSTORMS ACROSS MUCH OF THE AREA SUNDAY
MORNING.

AT THIS TIME...APPEARS THAT SNOW LEVELS BY MIDDAY SUN WILL BE AROUND
7000 FEET ACROSS THE WHITE MOUNTAINS TO AROUND 8000 FEET ACROSS THE
CATALINA/RINCON MOUNTAINS NEAR TUCSON. SEVERAL INCHES OF SNOW IS
POSSIBLE BY SUNDAY EVENING ACROSS THE WHITE MOUNTAINS ABOVE
7000 FEET...WITH 2 TO 4 INCHES OF SNOW ABOVE 7000 FEET ACROSS THE
CATALINA/RINCON MOUNTAINS AS WELL AS THE GALIURO/PINALENO MOUNTAINS
IN GRAHAM COUNTY. GUSTY WEST TO SOUTHWEST WINDS WILL CONTINUE FOR
MOST LOCATIONS THE REST OF TONIGHT FOLLOWED BY GUSTY WEST TO
NORTHWEST WINDS SUNDAY. COOLER TEMPS WILL OCCUR SUN AS THE UPPER LOW
BECOMES QUASI-STATIONARY OVER NRN NEW MEXICO.

PLEASE REFER TO THE ADDITIONAL SECTIONS FOR FURTHER DETAIL.

&&

.AVIATION...VALID THRU 27/06Z.
EXPECT SCATTERED TO NUMEROUS -SHRA ALONG WITH ISOLATED -TSRA THRU
SUNDAY AFTERNOON. THE BEST CHANCE FOR PRECIPITATION WILL BE NORTH
OF A SAN SIMON-KTUS-SELLS LINE. MVFR CONDITIONS MAY OCCUR ESPECIALLY
NEAR THE HIGHER TERRAIN NE OF KTUS TO THE WHITE MOUNTAINS. ISOLATED
TO SCATTERED -SHRA SUNDAY EVENING SHOULD BE CONFINED FROM VICINITY
OF KSAD TO THE WHITE MOUNTAINS.

OTHERWISE...CLOUD DECKS INTO MIDDAY SUNDAY WILL GENERALLY BE AT
6-10K FT AGL. GRADUALLY CLEARING SKIES WILL THEN OCCUR FROM WEST-TO-
EAST ACROSS SOUTHEAST ARIZONA SUNDAY AFTERNOON AND SUNDAY EVENING.
SURFACE WIND THE REST OF TONIGHT WILL MAINLY BE WLY/SWLY AT
10-20 KTS WITH GUSTS TO AROUND 25 KTS. SURFACE WIND SUNDAY WILL BE
WLY/NWLY AT 12-25 KTS WITH GUSTS OF 30-40 KTS. THE STRONGEST WIND IS
EXPECTED TO OCCUR NEAR THE NEW MEXICO BORDER. SURFACE WIND WILL
DIMINISH TO AROUND 10 KTS MOST SECTIONS TOWARD THE END OF THE
PERIOD...OR 27/06Z. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...A STRONG LOW PRESSURE SYSTEM MOVING NORTH OF THE
AREA WILL BRING A GOOD CHANCE OF SHOWERS AND PERHAPS A FEW
THUNDERSTORMS INTO SUNDAY. THE BEST CHANCE FOR PRECIPITATION IS
NORTH OF TUCSON. A FEW SHOWERS MAY OCCUR ACROSS THE WHITE MOUNTAINS
MONDAY AND TUESDAY. THEREAFTER...DRY CONDITIONS WITH WELL ABOVE
NORMAL DAYTIME TEMPERATURES WILL PREVAIL WEDNESDAY THROUGH SATURDAY.
EXPECT GUSTY WEST TO NORTHWEST WINDS SUNDAY ASSOCIATED WITH THE LOW
PRESSURE SYSTEM. GUSTY EAST WINDS SHOULD OCCUR TUESDAY.

&&

.PREV DISCUSSION...THE SYSTEM WILL CONTINUE TO EXIT TO THE EAST INTO
THE CENTRAL AND SOUTHERN PLAINS MONDAY BUT THE TAIL END OF THIS
SYSTEM WILL LINGER BACK ACROSS PARTS OF THE DESERT SOUTHWEST. A
SHARP MOISTURE GRADIENT IS ADVERTISED BY THE MODELS TO BE RIGHT
ALONG THE AZ/NM BORDER MONDAY INTO TUESDAY RESULTING IN LINGERING
ISOLATED SHOWERS...MAINLY OVER THE WHITE MOUNTAINS...BUT DRY
ELSEWHERE.

BEHIND THIS SYSTEM RIDGING WILL NOSE IN ACROSS SOUTHERN CALIFORNIA
AND THE GREAT BASIN LATE TUESDAY AND OVER ARIZONA ON WEDNESDAY AND
CONTINUING INTO THURSDAY. BEYOND THURSDAY MODELS SHOW SIGNIFICANT
DISCREPANCIES...SO DID NOT MAKE ANY CHANGES TO THE FORECAST...
ALTHOUGH AT THIS TIME IT LOOKS LIKE A DRY FORECAST IS IN STORE
REGARDLESS OF THE UNCERTAINTY AMONG THE MODELS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON

FRANCIS
PREVIOUS DISCUSSION...MOLLERE



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