Cold in Utah, November 30, 2004

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
300 AM MST TUE NOV 30 2004

.SYNOPSIS...A WEAK WEATHER DISTURBANCE WILL MOVE ACROSS NORTHERN
SECTIONS TUESDAY NIGHT AND WEDNESDAY. INVERSIONS WILL DOMINATE THE
VALLEYS MOST OF THE WEEK.

&&

.DISCUSSION...ANOTHER VERY COLD MORNING WITH MANY LOCALES IN THE
SINGLE DIGITS AND SOME BELOW ZERO...SHOWING UP ON IR IMAGE WELL.
FOG/STRATUS AREA EXPANDING NORTH END OF LAKE AND IN CACHE
VALLEY...AND WASATCH MTN VALLEYS. MAIN FORECAST ISSUE THIS WEEK WILL
BE TRAPPED COLD AIR IN THE VALLEYS THAT HAVE SNOW COVER AND THE
CURRENT WEAKLY INVERTED AIR MASS THAT BECOMES A STRONGER INVERSION
LATER THIS WEEK. HAVE LOWERED MAX TEMPS FOR MOST VALLEYS
TODAY...WARMING TODAY LIMITED TO HIGHER TERRAIN.

THERE IS A WELL DEFINED SHORT WAVE TROF ON WATER VAPOR SWINGING
ACROSS OREGON WHICH WILL PRODUCE HIGH CLOUDS TODAY AND MOVE OVER
NORTHERN SECTIONS TONIGHT AND WEDNESDAY MORNING. THIS WILL BRING
COLD AIR ALOFT BUT THE DEPTH OF COLD AIR IS BELOW 600 MB IN THE WAKE
OF THIS WAVE BY WEDNESDAY EVENING. MODELS IN BETTER AGREEMENT ABOUT
A CONSOLIDATED VORT MAX AND -26 TO -27C 500 MB TEMPS CROSSING THE
GSL AND 700 MB TEMPS DROPPING BACK TO -13 OR -14C ON WEDNESDAY OVER
THE NORTH. HOWEVER THERE IS ONLY A WEAK SURFACE COLD FRONT TONIGHT
AND LITTLE REFLECTION OVERALL AT THE SURFACE AS HIGH PRESSURE
QUICKLY BUILDS BACK IN OVER NORTHERN UTAH. LITTLE WINDOW FOR LAKE
ENHANCEMENT AS SUBSIDENCE INVERSION LOWERS TO 700-750 MB AGAIN BY
WEDNESDAY AFTERNOON. MOST SNOW LATER TONIGHT AND WEDNESDAY MORNING
WILL BE CONFINED TO THE MOUNTAINS DUE TO DYNAMICS AND SOME UPSLOPE
FLOW BUT GENERALLY LIGHT AMOUNTS. A SECONDARY ELONGATED SHORT WAVE
TROF WILL DROP SOUTH WEDNESDAY NIGHT AND THURSDAY AND CLOSE A WEAK
LOW OFF TO OUR SOUTHWEST. STRONGER WAVE CROSSES THE NORTHERN PLAINS.
PATTERN WILL HAVE LITTLE IMPACT BUT SOME CLOUDS. PARTIAL CLEARING
AND LIGHT WIND ALLOWS FOR A COLD THURSDAY MORNING. GFS BUFR
SOUNDINGS INDICATE INCREASE LOW LEVEL MOISTURE...THUS STRATUS AND
FOG COULD BE INCREASING PROBLEM OVER NORTHERN LOW LANDS.

INVERSION IS NOT STRONG THURSDAY BUT IT IS THERE AND VALLEYS WILL
STRUGGLE TO MIX LEADING TO COLD TEMPS. BY FRIDAY AIR QUALITY WILL BE
POOR ESPECIALLY IN THE CACHE VALLEY AND HAZY CONDITIONS SHOULD
INCREASE ALONG WITH AREAS OF FOG/LOW CLOUDS. TEMPS IN THE VALLEYS
WILL LIKELY GO DOWN INSTEAD OF THE MODERATE WARMING THAT WILL OCCUR
IN THE HIGHER TERRAIN. NEXT MORE SIGNIFICANT SHORT WAVE DUE TO BRING
RELIEF BUT NOT PROGGED UNTIL SATURDAY NIGHT AND VALLEY TEMPS WILL BE
KEPT DOWN SATURDAY WITH ONLY SLIGHTLY BETTER MIXING FROM INCREASING
WIND ALOFT. SYSTEM PROGGED TO DIG SUNDAY WITH THE INITIAL COLD FRONT
WHICH COULD BE FOLLOWED BUT A SECONDARY COLD FRONT SUNDAY NIGHT AND
THEN THE UPPER TROF AXIS ON MONDAY. 00Z GEM AND GFS STORM PROGGED TO
BE QUITE COLD AND SHOULD BRING SNOW DESPITE TENDING TO SPLIT. MODEL
AGREEMENT IS NOT GOOD WITH THIS SYSTEM...ECMWF DIGS WELL SOUTH AND
UKMET HANGS ENERGY OVER COAST. GFS ENSEMBLES DIG AS WELL BUT SPREAD
IS NOT LARGE AT 144H. GFS...ENSEMBLES AND GEM RUNS SUGGEST ACTIVE
PATTERN INTO EARLY WEDNESDAY WITH ANOTHER WAVE...ECMWF CLOSER TO
THESE MODELS BY THEN. WENT BELOW MOS FOR MAX AND MIN TEMPS IN THE
VALLEYS...SIGNIFICANTLY IN NARROWER VALLEYS...NEXT SEVERAL DAYS
ESPECIALLY THURSDAY INTO SATURDAY...CLOSER TO MOS AFTER SATURDAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
ID...NONE.

&&

TARDY