FXUS65 KSLC 051230 AFDSLC AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SALT LAKE CITY UT 630 AM MDT SUN JUN 5 2011 .SYNOPSIS...A DRY AND MILD SOUTHERLY FLOW WILL INCREASE THROUGH THE WEEKEND. COOLER AND UNSETTLED WEATHER CAN BE EXPECTED NEXT WEEK AS A PACIFIC STORM MOVES INLAND. && .DISCUSSION...DEEPER INSPECTION OF THE LOCAL 12KM WRF-NMM SUGGESTS THAT THE HIGH WIND WATCH FOR TOMORROW MAY NEED TO BE EXPANDED NORTHWARD TO INCLUDE THE NORTHERN WASATCH FRONT AND CACHE VALLEY. THE MODEL SHOWS A TROPOPAUSE FOLD CROSSING NORTHERN UTAH DURING THE LATE AFTERNOON HOURS WHICH IS JUXTAPOSED WITH 60KTS OF AVERAGE FLOW WITHIN THE 700-500MB MIX LAYER. 4KM CRAS WATER VAPOR SATELLITE FORECAST SHOWS THE FORECAST DRY SLOT PROGRESSING COINCIDENTALLY WITH THE HIGHER POTENTIAL VORTICITY ON THE LOCAL 12KM WRF-NMM. NO CHANGES AT THIS TIME...BUT SOMETHING TO CONSIDER FOR LATER SHIFTS. PREVIOUS DISCUSSION... WATER VAPOR LOOP SHOWS RIDGING DOMINATING THE CENTRAL CONUS WITH AN UPPER LOW NEARLY STATIONARY OFF THE CALIFORNIA COAST. ASIDE FROM A FEW PATCHES OF HIGH CLOUDS ACROSS NORTHWEST UTAH...IT WILL BE A SUNNY DAY. A 4C INCREASE IN 700MB TEMPERATURES BETWEEN LAST EVENING AND THIS EVENING WILL SUPPORT WARMING TEMPERATURES WELL INTO THE 80S NORTHERN VALLEYS AND NEAR 100F SOUTHERN VALLEYS. SOUTHERLY FLOW CONTINUES TO INCREASE COMPARED TO YESTERDAY WITH THE CYCLONE OFF THE PACIFIC COAST. BY MONDAY...SOUTHERLY FLOW AT 700MB INCREASES TO BETWEEN 40-50KTS AHEAD OF THE COLD FRONT WHICH CROSSES NEVADA DURING THE MORNING AND WESTERN UTAH DURING THE AFTERNOON. QUITE A DYNAMIC SITUATION WITH 10DM HEIGHT FALLS MONDAY. INSPECTION OF NAM/LOCAL 12KM WRF-NMM BUFKIT FORECAST SOUNDINGS INDICATE DEEP LAYER MIXING UP TO 500MB WHICH IS BELIEVABLE GIVEN THE DYNAMICS. LOOKING AT A 700-500MB LAYER AVERAGE OF WINDS...WESTERN UTAH COULD EASILY MIX TO 50-70KTS. THIS PATTERN FITS THE CONCEPTUAL MODEL FOR A DYNAMIC HIGH WIND EVENT FOR UTAH. HAVE ISSUED A HIGH WIND WATCH FOR THE WESTERN ZONES INCLUDING THE SALT LAKE AND TOOELE VALLEYS. LOOKS LIKE ALL OF THE REMAINDER OF THE UTAH ZONES WILL NEED A WIND ADVISORY. SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS NORTHERN UTAH AS DIFLUENT FLOW INCREASES DUE TO THE APPROACH OF THE MID LEVEL CIRCULATION. 21Z SHORT RANGE ENSEMBLES INDICATE 40KTS OF EFFECTIVE SHEAR WILL BE POSSIBLE MONDAY AFTERNOON AND EVENING ACROSS FAR NORTHERN UTAH INTO IDAHO. ORGANIZED ACTIVITY WILL LIKELY DEVELOP ACROSS NORTHERN UTAH THEN PROPAGATE NNE INTO IDAHO. COOLER WEATHER IS FORECAST TUESDAY THROUGH MUCH OF NEXT WEEK...WITH PERIODIC SPOTTY CONVECTION ACROSS NORTHERN UTAH. GFS/EUROPEAN IN DECENT AGREEMENT THAT THE FIRST IMPULSE EXITS BY BY TUESDAY MORNING...WITH A SECONDARY FEATURE ARRIVING IN DEVELOPING SOUTHWEST FLOW ALOFT DURING THE MID WEEK. A NORTHERN STREAM UPPER LOW DROPS ACROSS THE NORTHERN ROCKIES FOR THE SECOND HALF OF THE WORK WEEK. && .HYDROLOGY...A FLOOD WARNING REMAINS IN EFFECT FOR THE WEBER RIVER SYSTEM BELOW ECHO RESERVOIR TO ITS TERMINATION AT THE GREAT SALT LAKE AND LOST CREEK FROM ITS RESERVOIR TO THE CONFLUENCE OF THE WEBER. OTHER FLOOD WARNINGS IN EFFECT ARE FOR THE SOUTH FORK OF THE OGDEN AND ALONG PORTIONS OF THE SEVIER RIVER. REFER TO THE LATEST FLOOD STATEMENTS FOR FURTHER DETAILS/IMPACTS ON ALL FLOOD WARNINGS. TEMPERATURES WILL WARM AND ACCELERATE THE SNOWMELT AT THE HIGHER ELEVATIONS THROUGH MONDAY. THIS WILL REQUIRE VERY CLOSE MONITORING OF AREA STREAMS/RIVERS AS SUNDAY IS EXPECTED TO BE THE WARMEST DAY THUS FAR THIS YEAR...AND TEMPERATURES WILL REMAIN ABOVE FREEZING IN ALMOST ALL LOCATIONS FOR A 72 HOUR PERIOD. && .AVIATION...SOUTHERLY WINDS WILL PERSIST AT THE SLC TERMINAL INTO THE AFTERNOON. THEY SHOULD SWITCH TO THE NORTHWEST LATER THAN NORMAL TODAY...ABOUT 21-22Z WITH A 20 PERCENT CHANCE OF HOLDING OFF UNTIL 23Z. WINDS COULD BECOME GUSTY FOR A TIME THIS MORNING THROUGH EARLY AFTERNOON BETWEEN ABOUT 16-19Z. SKIES SHOULD BE MOSTLY CLEAR. && .FIRE WEATHER...THE LOW ALONG THE CA COAST WILL MAINTAIN A DRY SOUTHERLY FLOW ACROSS THE FIRE DISTRICTS TODAY. HUMIDITIES WILL REMAIN LOW WITH MOST READINGS WELL BELOW 15 PERCENT ACROSS MOST VALLEYS. WINDS JUST TOUCHED CRITICAL VALUES YESTERDAY ACROSS THE FAR SOUTHWEST AND ARE EXPECTED TO BE A LITTLE STRONGER TODAY SO HAVE ISSUED A RED FLAG WARNING FOR THE TWO FAR SOUTHWEST ZONES WHERE FUELS ARE DEEMED CRITICAL. WINDS SHOULD INCREASE SIGNIFICANTLY MONDAY AND SHOULD EXCEED CRITICAL SPEEDS ACROSS MOST AREAS...BUT HUMIDITIES MAY NOT DROP QUITE AS LOW IN THESE WESTERN VALLEYS AS THE LOW SWINGS NORTHEAST ACROSS THE DISTRICT. SO HAVE LEFT THE WATCH IN EFFECT FOR MONDAY AT THIS TIME. HAVE ALSO KEPT THE WATCH FOR THE EASTERN VALLEYS MONDAY ALTHOUGH IT LOOKS MORE LIKE HUMIDITIES WILL FALL BELOW 15 PERCENT IN THAT AREA. HUMIDITY RECOVERIES WILL BE POOR TONIGHT BUT SHOULD IMPROVE ACROSS THE NORTH AND WEST MONDAY NIGHT...WHILE REMAINING LOW ACROSS SOUTHEAST UTAH. WINDS WILL DIMINISH IN ALL AREAS MONDAY NIGHT THROUGH TUESDAY AS THE COOLER MORE STABLE AIRMASS SPREADS IN BEHIND THE DEPARTING LOW. NOT MUCH IN THE WAY OF RAIN IS EXPECTED FROM THIS SYSTEM. THE ONLY CHANCE OF WETTING RAINS WILL BE ALONG THE IDAHO BORDER MONDAY AFTERNOON INTO TUESDAY MORNING. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 8 PM MDT THIS EVENING BELOW 6000 FEET FOR UTZ439-440. FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING BELOW 6000 FEET FOR UTZ431-432-438>441. HIGH WIND WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR UTZ003-005-015-016. WY...NONE. && $$ PUBLIC/HYDROLOGY...ROGOWSKI FIRE WEATHER/AVIATION...WILENSKY FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT... HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE) FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION VISIT... HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)