Severe Thunderstorm Warning 77, NWS Huntsville, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1038 AM CDT TUE MAY 20 2008

.UPDATE...
MADE MINOR INCREASE TO POPS...BUT SLIGHT CHANCE/CHANCE WORDING IN
CURRENT ZONE GROUPINGS WILL ESSENTIALLY REMAIN THE SAME. DECREASED
CLOUD COVER FOR THE REMAINDER OF THE MORNING IN THE WEST...AND
INCREASED IN THE EAST. NO OTHER CHANGES MADE AT THIS TIME.

&&

.DISCUSSION...
SHORT TERM CHALLENGES CENTER AROUND CONVECTIVE/PRECIP CHANCES AS
COLD FRONT MOVES THROUGH THE AREA THIS AFTN. BASICALLY...HAVE KEPT
FCST TAILORED TO SHOW SLIGHTLY HIGHER POPS/QPF IN SERN AREAS WHICH
WILL EXPERIENCE THE FRONTAL PASSAGE LATER IN THE AFTN...AND THUS
CAN REALIZE BETTER HEATING/DESTABILIZATION. FRONT SHOULD CROSS
THROUGH KHSV 3-4 PM...AND THROUGH OUR SE BORDER AROUND 7PM. LOW-
LVL CONVERGENCE ALONG THE FRONTAL BOUNDARY SHOULD GIVE RISE TO
ISOLD/SCATTERED CONVECTION THIS AFTN. HAVE THUS MAINTAINED GENERAL
20-30 POPS ACROSS THE AREA...WITH HIGHER CHANCES IN THE SE AS
MENTIONED EARLIER. OVERALL SHEAR IS RATHER WEAK...WITH NEARLY
UNIDIRECTIONAL FLOW FIELD AND SMALL SPEED SHEAR IN THE LOW-LVLS
GIVING NEARLY STRAIGHT HODOGRAPHS. HOWEVER...RELATIVELY DRY AIR
ABOVE 700MB AND SLIGHT INVERTED-V SIGNATURE IN SOUNDINGS
INDICATES...THE POTENTIAL FOR A STRONG/DAMAGING WIND THREAT. IN
ADDITION...FAIRLY ROBUST SB CAPE VALUES 1500J/KG...LI VALUES -5C
TO -6C AND WET-BULB ZERO HEIGHTS 9.5KFT...COULD PRODUCE A SMALL
TO PERHAPS LARGE HAIL THREAT. BUT...THESE INSTANCES SHOULD BE
ISOLATED GIVEN THE COVERAGE OF CONVECTIVE ACTIVITY EXPECTED.

&&

.PREV DISCUSSION... /ISSUED 247 AM CDT TUE MAY 20 2008/

DISCUSSION...
A BROAD SCALE VIEW ACROSS THE NORTH AMERICAN DOMAIN...THE WATER VAPOR
LOOP INDICATED AN UPPER LOW OVER THE ALASKA PANHANDLE/BRITISH
COLUMBIA COAST WITH AN UPPER JET DIVING SE TOWARD THE PACIFIC NW.
THIS WESTERN SYSTEM...ALONG WITH MEAN RIDGING OVER THE WESTERN
PLAINS... AND PERSISTENT UPPER LOW PRESSURE OVER THE EASTERN GREAT
LAKES/NEW ENGLAND REGION WILL SET UP INTO AN OMEGA STYLE BLOCK ACROSS
NORTH AMERICA FOR THE GREATER PART OF THIS WEEK. WITH THIS AREA IN A
NOT TOO BAD PART OF THE BLOCK...A GENERALLY UNSETTLED WEATHER PATTERN
IS EXPECTED THIS WORK WEEK.

AT THE SURFACE...A WEAK LOW WAS MOVING ACROSS EAST CENTRAL KENTUCKY
WITH A COLD FRONT EXTENDING NORTH AND WESTWARD TO ACROSS WESTERN
IOWA. SHOWER AND T-STORM ACTIVITY WITH THIS SYSTEM SO FAR HAS BEEN
FROM ALONG THE KY/TN BORDER AND POINTS NORTH AND EAST. LOCALLY...
AREA DEWPOINTS HAVE RISEN FROM THE MID/UPPER 40S LATE MONDAY
AFTERNOON NOW INTO THE MID/UPPER 50S. THESE HIGHER DEWPOINTS ALONG
WITH A STRONG LOW LEVEL JET OVER 50KTS A COUPLE OF THOUSAND FEET
ALOFT HELPS MAKES FOR A SLIGHT CHANCE OF A SHOWER FORMING BEFORE
DAYBREAK TUESDAY.

WITH THE COLD FRONT BEING SOUTH OF THE REGION TONIGHT...HAVE KEPT
LINGERING SHOWERS IN FOR OUR EASTERN AREAS THIS EVENING. THE POST
FRONTAL COLD AIR WILL LOWER HIGH TEMPERATURES ON WEDNESDAY INTO
THE 70S. AN UPPER DISTURBANCE NEARING THE REGION DURING THURSDAY
WILL BRING A CHANCE OF RAIN BACK TO THE FORECAST. WITH STRONG
LATER MAY SUN...HIGH TEMPERATURES SHOULD WARM UP SOMEWHAT TO
AROUND 80...LOWER 80S FOR THU/FRI.

FOR THE REMAINDER OF THE FORECAST PERIOD INTO NEXT MONDAY...MEMORIAL
DAY A DRYING AND WARMER TREND IS IN THE WORKS. THE EASTERN PART OF
THE BLOCK SHOULD GRADUALLY WEAKEN AND MOVE OUT TO SEA...WHILE UPPER
RIDGING MOVES FROM THE WESTERN PLAINS TO ACROSS THIS REGION. HIGH
TEMPS FOR THE OFFICIAL START OF THE SUMMER SEASON SHOULD WARM INTO
THE MID 80S FOR MEMORIAL DAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    85  54  75  54 /  20  10  10  10
SHOALS        85  54  75  54 /  20  10  10  10
CULLMAN       85  56  76  55 /  30  10  10  10
FAYETTEVILLE  84  54  73  53 /  20  10  10  10
ALBERTVILLE   86  56  76  55 /  30  20  10  10
FORT PAYNE    86  55  74  53 /  30  20  10  10

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

UPDATE...KDW.03
PREV DISCUSSION...RSB

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
158 PM CDT TUE MAY 20 2008

ALZ001>010-016-TNZ076-096-097-210300-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DE KALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
158 PM CDT TUE MAY 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH ALABAMA AND PORTIONS
OF SOUTHERN MIDDLE TENNESSEE.

.DAY ONE...TODAY AND TONIGHT...

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

ISOLATED STRONG TO SEVERE THUNDERSTORMS REMAIN POSSIBLE THIS
AFTERNOON AHEAD OF AN APPROACHING COLD FRONT.  INITIAL DEVELOPMENT
OF STORMS IS OCCURRING IN SOUTHERN MIDDLE TENNESSEE...AND WILL
SHIFT SOUTHEAST OF A SCOTTSBORO...GUNTERSVILLE...VINEMONT LINE AFTER
4 PM.  THE MAIN SEVERE WEATHER THREATS FROM THESE STORMS WILL BE
HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY...

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

A MORE UNSETTLED WEATHER PATTERN SHOULD DEVELOP BY THE END OF THE
WEEK INTO THE WEEKEND WITH SCATTERED THUNDERSTORMS POSSIBLE EACH
DAY.

.SPOTTER CALL TO ACTION STATEMENT...

FORMAL ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT
PERSONNEL IS NOT ANTICIPATED TODAY.  HOWEVER...SPOTTERS AND
EMERGENCY MANAGEMENT ARE ENCOURAGED TO PROVIDE REPORTS OF ANY SEVERE
WEATHER OCCURRENCES.

KULA