FXUS64 KHUN 020258 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 858 PM CST SAT FEB 1 2014 .UPDATE... RAISED TEMPS A FEW DEGREES MAINLY WEST OF I65. && .DISCUSSION... CDFNT NOW EXTENDS FROM THE OHIO VALLEY THRU SERN MO AND INTO ERN TX. ALONG THE CDFNT WAS A BAND OF LIGHT RAIN WITH SOME FZRA/SNOW BACK IN THE COLDER AIR OVER PARTS OF THE MIDWEST/OHIO VALLEY. OVER THE TN VALLEY TEMPS WERE RANGING FROM THE MID 40S IN NE AL TO THE MID 50S OVER NW AL. DEWPOINTS WERE MAINLY BETWEEN 40 AND 45. WITH S/SE WINDS AND INCREASING CLOUD COVER...NOT EXPECTING TEMPS TO DROP MUCH FROM WHERE THEY ARE NOW...THUS RAISED TEMPS A FEW DEGREES ESPECIALLY WEST OF I-65. A LARGE SFC HIGH PRESSURE SYSTEM OVER THE SERN US WILL KEEP THE RAIN OUT OF THE TN VALLEY UNTIL AFTER MIDNIGHT...MORE TOWARDS SUNRISE. CURRENT FCST HAS LOW POPS ACROSS THE CWA AFTER MIDNIGHT WHICH LOOKS GOOD ATTM. OTHERWISE REST OF THE FCST LOOKS GOOD. 07 && .AVIATION... /ISSUED 609 PM CST SAT FEB 1 2014/ FOR 00Z TAFS...A CDFNT ACROSS SERN MO...WILL CONTINUE TO MOVE TOWARDS THE TN VALLEY OVERNIGHT BRINGING MVFR CEILINGS ARND 09Z AT BOTH KMSL AND KHSV. THE CHC OF SHRA WILL INCREASE AFTER 12Z AS THE CDFNT APPROACHES THE TAF SITES. THE CDFNT WILL MOVE ACROSS THE TAF SITES BETWEEN 18Z AND 20Z...WITH IFR CONDITIONS AND WIDESPREAD SHRA ACTIVITY. 07 && .PREV DISCUSSION... /ISSUED 525 PM CST SAT FEB 1 2014/ THE LATEST 21Z SURFACE ANALYSIS AND SATELLITE IMAGERY INDICATED THAT THE SURFACE COLD WAS EXTENDING SOUTHWEST FROM SOUTHERN ILLINOIS THROUGH SOUTHEAST MISSOURI AND INTO NORTHWEST ARKANSAS. TEMPS ACROSS THE FORECAST AREA THIS MID AFTERNOON HAD WARMED WELL INTO THE UPPER 50S TO LOWER TO MID 60S. EXPECT CLOUDS TO GRADUALLY INCREASE OVERNIGHT IN ADVANCE OF THE COLD FRONT. HAVE FOLLOWED CLOSELY TO GUIDANCE TEMPS OVERNIGHT. THE COLD FRONT WILL SLOWLY SHIFT SOUTHEAST INTO THE AREA DURING THE DAY ON SUNDAY AND WILL SPREAD PRECIP ACROSS THE REGION. HAVE CONTINUED WITH HIGH POPS FOR SUNDAY AND HAVE MADE SOME SLIGHT ADJUSTMENTS UPWARD INVOLVING TEMPS DUE TO THE SLIGHTLY LATER EXPECTED COLD FRONTAL PASSAGE ACROSS THE FORECAST AREA. COLD ADVECTION IS EXPECTED TO CONTINUE OVERNIGHT ON SUNDAY NIGHT AND INTO EARLY MONDAY. FORECAST SOUNDINGS FROM THE NAM MODEL ARE MORE IN LINE WITH THE EXPECTED DEPTH OF THE COLD ADVECTION AND HAVE MADE SOME ADJUSTMENTS FOR EARLY MONDAY MORNING TO ADD IN A MENTION OF A SLIGHT CHANCE OF SLEET/FREEZING RAIN MIXTURE WITH RAIN DUE TO THE DEPTH OF THE COLD ADVECTION FROM SURFACE TO AROUND 925 MILLIBARS AND THEN DECENT WARM ADVECTION UP TO AROUND 750 MILLIBARS. EITHER WAY...THERE WILL BE A WINDOW OF AROUND 4-6 HOURS AFTER 09Z TO AROUND 15Z FOR THE POTENTIAL FOR A WINTRY MIX...ESPECIALLY ALONG AND NORTH OF THE TENNESSEE/ALABAMA STATE LINE. WITH DECENT COLD ADVECTION CONTINUING ON MONDAY...HAVE TRENDED MORE TOWARD ECMWF MODEL TEMP GUIDANCE. BY MONDAY AFTERNOON...A STRONG SHORTWAVE IN THE SOUTHERN STREAM IS EXPECTED TO LIFT NORTHEAST INTO THE SOUTHERN PLAINS BY WEDNESDAY. A SURFACE COLD FRONT AND A WEAK SURFACE LOW AHEAD OF THE SHORTWAVE WILL MOVE INTO NORTHEAST MISSISSIPPI BY AROUND 00Z WEDNESDAY. THIS COLD FRONT WILL RAPIDLY MOVE EAST ACROSS THE FORECAST AREA BETWEEN 06Z AND 12Z WEDNESDAY. LOW LEVEL WINDS BETWEEN 850 AND 925 MILLIBARS ARE STILL EXPECTED TO RANGE FROM 60-65 KNOTS AND EXPECT WINDY CONDITIONS WITH MARGINAL INSTABILITY BUT STRONG SHEAR ALONG THE EXPECTED LINE OF SHRA/TSRA. STRONG COLD ADVECTION BEHIND THE COLD FRONT WILL LIKELY RESULT IN NEAR STEADY TEMPS ACROSS THE FORECAST AREA ON WEDNESDAY...WHICH WOULD BE MORE IN LINE WITH GFS TEMP GUIDANCE. BY THURSDAY...AN AREA OF LOW PRESSURE IN THE FAR WESTERN GULF OF MEXICO IS PROGGED BY THE ECMWF AND GFS MODELS TO DEVELOP ALONG THE WESTERN END OF THE OLD COLD FRONT. THIS LOW PRESSURE AREA WILL SHIFT NORTHEAST INTO EAST TEXAS AND NORTHERN LOUISIANA BY 12Z FRIDAY. A SIGNIFICANT LOW LEVEL MOISTURE INCREASE WILL BE EVIDENT INTO THE FORECAST AREA AND HAVE AT LEAST A SLIGHT CHANCE OF RAIN ACROSS THE AREA TOWARD 12Z FRIDAY. THE GFS MODEL IS SLOWER WITH THE MOVEMENT OF THE PRECIP ASSOCIATED WITH THIS SYSTEM...COMPARED TO A QUICKER EASTWARD MOVEMENT OF THE PRECIP BY THE ECMWF MODEL. HAVE SLIGHTLY BUMPED UP PRECIP CHANCES FOR FRIDAY AND FRIDAY NIGHT AND CONTINUED A LINGERING CHANCE OF PRECIP FOR SUNDAY. TEMPS SHOULD REMAIN CLOSER TO THE ECMWF TEMP GUIDANCE THROUGH THE END OF THE EXTENDED FORECAST PERIODS. TT && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.
Posted on: Sun, 02 Feb 2014 02:58:52 +0000
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