AREA FORECAST DISCUSSION

 
 FXUS65 KTWC 100912
 AFDTWC
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE TUCSON AZ
 215 AM MST WED FEB 10 2010
 
 .SYNOPSIS...A STRONG PACIFIC LOW PRESSURE SYSTEM WILL BRING VALLEY 
 RAIN AND MOUNTAIN SNOW ACROSS SOUTHEAST ARIZONA LATER TODAY INTO 
 EARLY THURSDAY. THIS SYSTEM WILL BE COLD WITH SIGNIFICANT SNOW 
 ACCUMULATIONS POSSIBLE ABOVE 4000 FEET OR EVEN LOWER. DRY AND WARMER 
 CONDITIONS WILL BEGIN FRIDAY AND CONTINUE INTO EARLY NEXT WEEK UNDER 
 HIGH PRESSURE.
 
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 .DISCUSSION...STRONG LOW WINDING UP WITH ONE MORE PIECE OF 
 REINFORCING ENERGY NOW NEAR SAN DIEGO. STILL WOBBLING SOUTHEAST AS 
 IT SLOWS SLIGHTLY BEFORE A TRACK THROUGH SOUTHERN ARIZONA AND 
 NORTHERN SONORA OVER THE NEXT 36 HOURS. STARTING TO TAP INTO SOME 
 NICE MOISTURE NOW AS WELL. BANDS OF CONVECTION WITH BUSY CG 
 LIGHTNING PROFILES EXTENDING FROM THE GULF OF CALIFORNIA AND 
 NORTHERN BAJA INTO FAR SOUTHWEST ARIZONA. A GOOD SOLID COLD SYSTEM 
 WITH A STRONG FAVORABLY ORIENTED JET...PLENTY OF ENERGY AND A 
 NICE MOISTURE SUPPLY...WE ARE COMFORTABLE WITH OUR 70 TO 100 POPS 
 AND AND CONVERSION OF WINTER STORM WATCH TO A WINTER STORM WARNING 
 WITH THIS FORECAST PACKAGE. SAME TIMING AND ELEVATIONS WITH BEST 
 SHOWERS MOVING IN LATER THIS AFTERNOON AS SNOW LEVELS FALL TOWARD 4K 
 FEET. EVENING HOURS MAY SEE SNOW LEVELS AS LOW AS 3500 FEET OR EVEN 
 LOWER IN THE VICINITY OF CONVECTION...BUT SIGNIFICANT ACCUMULATIONS 
 ARE STILL EXPECTED TO BE CONFINED TO LOCATIONS AT OR ABOVE 4000 FEET.
 
 SOME WRAP-AROUND ESPECIALLY EASTERN AREAS THURSDAY MORNING BEFORE 
 FAIRLY RAPID CLEARING FROM THE WEST. WITH RESIDUAL BOUNDARY LAYER 
 MOISTURE AND COLD AIR...FROST AND/OR FOG MAY BE A LOCALIZED CONCERN 
 FOR A MORNING OR TWO. SOUTHERN BRANCH RECONSOLIDATION AS THE PATTERN 
 CHANGE BRINGS A RIDGE TO DOMINATE OUR WEATHER OVER THE WEEKEND INTO 
 NEXT WEEK.
 
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 .AVIATION...THRU 16Z CLOUD DECKS LOWERING TO 6-9K FT AGL. AFTER 16Z 
 WEDNESDAY AND CONTINUING INTO WEDNESDAY NIGHT CLOUD DECKS GENERALLY 
 5-8K FT AGL...ALONG WITH AREAS OF MVFR AND LOCAL IFR CONDITIONS DUE 
 TO VALLEY SHRA AND HIGHER TERRAIN SHSN ESPECIALLY KTUS VICINITY 
 EWD/SWD. SURFACE WINDS THRU 16Z SELY/SLY GENERALLY LESS THAN 10 
 KTS....THEN SWLY-WLY 10-20 KTS WITH GUSTS TO AROUND 25 KTS. AVIATION 
 DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
 
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 .FIRE WEATHER...NO FIRE WEATHER CONCERNS AT THIS TIME.
 
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 .TWC WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING IN EFFECT
      FROM THIS AFTERNOON THROUGH THURSDAY MORNING ABOVE 4000 FEET
      AZZ019-029-030-032>035.
     
 

 
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