Flash Flood Warning 3, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
450 PM CST FRI MAR 12 1999

PROBLEM(S) OF THE DAY:
HOW MUCH SNOW WILL ACCUMULATE?
WILL WINTER STORM WARNING CRITERIA BE MET?

LOOKS LIKE THE REAL MCCOY FOR SNOW IN THE NEXT 36 HOURS. HAVE NOT
SEEN A SNOW SETUP LIKE THIS IN OK/NW AR IN SOME TIME. LOTS OF DETAILS
TO DEAL WITH THOUGH. FIRST...WHEN WILL RAIN CHANGE TO SNOW? HAVE
ALREADY GOTTEN REPORTS OF SNOW MIXING WITH RAIN IN TULSA AND OSAGE
COUNTIES. SOME OF THIS MAY BE MESOSCALE WITH THE STRONG LIFTING
ASSOCIATED WITH THE EASTWARD MOVING BAND...SO A BRIEF CHANGE BACK TO
RAIN MAY OCCUR THIS EVENING BEFORE MORE TRULY COLDER AIR MOVES IN
LATER THIS EVENING. SNOW AMOUNTS WILL DEPEND LARGELY ON WHEN THE
CHANGEOVER TAKES PLACE. IF THE CHANGEOVER OCCURS LATE THIS EVENING AS
EXPECTED...24 HOUR WINTER STORM WARNING CRITERIA OF 6 INCHES MAY BE
MET ALONG AND NORTH OF I-44. AS A WORST CASE SCENARIO...IMAGINE THE
NGM'S QPF VERIFYING WITH THE ETA'S TEMPERATURE FIELD AND WE ARE
TALKING ABOUT A FOOT OF SNOW IN A NARROW BAND ALONG I-44. THE NGM'S
QPF IS HIGHER LARGELY BECAUSE OF ITS SLOWER MOVEMENT OF THE SURFACE
LOW. WITH A BLOCKY PATTERN DEVELOPING THE SLOWER MOVEMENT IS
POSSIBLE...THOUGH I DO NOT FEEL GOOD FORECASTING A RECORD SNOW
EVENT...EVEN THOUGH IT IS MARCH. AGAIN 6 INCHES IS NOT OUT OF THE
QUESTION.

ON SATURDAY...A DRY SLOT WILL PUSH ACROSS THE AREA IN ADVANCE OF THE
MAIN UPR LOW AND CAUSE A LIKELY RESPITE IN THE SNOW FOR PART OF THE
DAY. ENOUGH COLD AIR WILL MOVE IN ON SAT MRNG FOR THERE TO BE
ACCUMULATION AS FAR SOUTHEAST AS MLC-FYV BEFORE THE DRY SLOT CUTS OFF
PRECIP LATE SAT MRNG. AS THE UPR SYS MOVES OVERHEAD AND PASSES...MORE
ISENTROPIC LIFT KICKS IN BEHIND THE LOW...SO WRAPAROUND SNOW WILL
MOVE INTO THE AREA. THERE WILL LIKELY BE A NARROW STRIPE OF HEAVY
SNOW STRETCHING FROM SOMEWHERE IN SE OK TO NW AR. SINCE THIS IS IN
THE THIRD PERIOD...WILL NOT INCLUDE SPECIFIC ACCUMULATIONS IN THE
ZONE FORECAST...THOUGH 4 TO 6 INCHES WOULD NOT BE OUT OF THE
QUESTION. AGAIN...IF THE HEAVIER QPF OF THE NGM VERIFIES...THAT COULD
BE AN UNDERESTIMATE.

IN THE FAR SOUTH...WENT WITH FLASH FLOOD WATCH FOR TONIGHT BASED ON
MORE CONVECTIVE NATURE OF PRECIP THERE. MESONET SHOWS SOME LOCALES IN
S-CENTRAL OK WITH OVER 2 INCHES OF RAIN.

THANKS FOR COORD...OUN...SHV...LIT.

FCSTID = 22
TUL   32  35  28  45 / 100  60  70  30
FSM   36  37  30  42 / 100  70  80  50
MLC   34  37  29  45 / 100  60  80  40
BVO   27  31  23  40 / 100  60  60  30
FYV   33  35  27  39 / 100  80  80  50
IDB   37  41  31  45 / 100  60  70  40
BYV   32  35  27  38 / 100  80  80  50
MIO   30  33  25  39 / 100  70  80  30
MKO   30  33  26  45 / 100  60  70  40
F10   32  35  28  45 / 100  60  70  30
HHW   37  41  31  45 / 100  60  70  40

.TUL...
OK...WINTER STORM WARNING TONIGHT FOR ZONES OKZ054>067.

FLASH FLOOD WATCH FOR TONIGHT FOR ZONES OKZ049...OKZ053...OKZ077.

AR...NONE.

--------------------
EXPERIMENTAL OUTPUT:

HAZARDOUS WEATHER EXPECTED NEXT 24 HOURS: LIKELIHOOD SNOW
NGM CONFIDENCE:  7 ON A SCALE OF 0 TO 10
ETA CONFIDENCE:  7 ON A SCALE OF 0 TO 10
AVN CONFIDENJCE:  8 ON A SCALE OF 0 TO 10
FCST CONFIDENCE: 8 ON A SCALE OF 0 TO 10

ARZ001-002-010-011-019-020-029-OKZ049-053>076-131200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
100 PM CST FRI MAR 12 1999

...MAJOR STORM SYSTEM WILL AFFECT EASTERN OKLAHOMA AND NORTHWEST
ARKANSAS THROUGH SATURDAY...

ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THROUGH TONIGHT ACROSS
SOUTHEAST OKLAHOMA AND WEST CENTRAL ARKANSAS.

.SYNOPSIS...
A STRONG UPPER LEVEL STORM WILL MOVE FROM WESTERN NEW MEXICO INTO WEST
TEXAS THROUGH TONIGHT...THEN INTO WESTERN OKLAHOMA BY EARLY SATURDAY.
AS THE UPPER LEVEL STORM APPROACHES...SURFACE LOW PRESSURE ORGANIZING TO
THE SOUTH ACROSS TEXAS WILL MOVE EAST.  THIS STORM SYSTEM WILL PRODUCE
A VARIETY OF INCLEMENT WEATHER ACROSS THE AREA.

WIDESPREAD RAIN WITH EMBEDDED THUNDERSTORMS WILL CONTINUE TO SPREAD
ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS INTO TONIGHT.  THE
PRECIPITATION WILL EVENTUALLY CHANGE OVER TO SNOW...OR A RAIN SNOW MIX
BEGINNING IN AREAS TO THE NORTHWEST OF TULSA...THEN DEVELOPING FURTHER
TO THE SOUTH AND EAST DURING THE NIGHT AND EARLY SATURDAY.

WIDESPREAD RAINFALL AMOUNTS OF 1 TO 2 INCH WILL ALSO OCCUR WITH THIS
SYSTEM THROUGH TONIGHT WITH ISOLATED HIGHER AMOUNTS POSSIBLE.  IF
RAINFALL BECOMES HEAVIER THAN ANTICIPATED...SOME FLOODING PROBLEMS MAY
RESULT.

AS THE SURFACE LOW MOVES INTO FAR EASTERN TEXAS LATER TONIGHT...COLDER
AIR WILL BE DRAWN SOUTH INTO NORTHEAST OKLAHOMA CHANGING THE RAIN TO
SNOW.  THE SNOW MAY BECOME HEAVY AT TIMES IN AREAS TO THE NORTH AND
NORTHWEST OF TULSA.  FOR THIS REASON...A WINTER STORM WATCH HAS BEEN
ISSUED FOR AREAS TO THE NORTH AND NORTHWEST OF TULSA FOR TONIGHT AND
SATURDAY.  PLEASE REFER TO THE OKCWSWTUL PRODUCT FOR MORE INFORMATION
ON THE WINTER STORM WATCH.

THE UPPER LEVEL STORM WILL MOVE ACROSS OKLAHOMA SATURDAY WITH THE RAIN
CHANGING TO SNOW ACROSS A LARGE PORTION OF EASTERN OKLAHOMA AND
NORTHWEST ARKANSAS BEFORE THE PRECIPITATION ENDS LATER SATURDAY NIGHT.
THERE IS SOME POTENTIAL FOR ACCUMULATIONS SOUTH OF THE WINTER STORM
WATCH AREA...BUT AMOUNTS SHOULD BE LESS THAN THOSE SEEN TO THE NORTH.

.DISCUSSION...
STRONG TO SEVERE THUNDERSTORMS WILL CONTINUE INTO THIS EVENING IN THE
VICINITY OF THE SURFACE LOW OFF TO THE SOUTH.  THESE STORMS WILL
CONTINUE TO MOVE NORTHEAST TOWARD SOUTHEAST OKLAHOMA BUT WILL BE
WEAKENING AS THEY MOVE DEEPER INTO THE COLD AIR IN PLACE ACROSS SOUTHERN
OKLAHOMA AND NORTHERN TEXAS.  AN ISOLATED STORM OR TWO MAY REMAIN STRONG
ENOUGH AS THEY CROSS THE RED RIVER TO PRODUCE HAIL AROUND 3/4 INCH IN
DIAMETER THIS EVENING.  THE HAIL POTENTIAL SHOULD LESSEN AS THE STORMS
CONTINUE MOVING FURTHER NORTHEAST...SO THE THREAT OF ISOLATED SEVERE
THUNDERSTORMS WILL BE CONFINED MAINLY TO AREAS SOUTH OF I-40.

.EMERGENCY AGENCY AND SPOTTER ACTIVATION...
SPOTTER ACTIVATION IS NOT EXPECTED THROUGH TONIGHT...BUT EMERGENCY
MANAGERS ARE URGED TO CHECK LATER FORECASTS AND STATEMENTS WHICH WILL
FURTHER UPDATE THIS DEVELOPING WEATHER SITUATION.

ARZ001-002-010-011-019-020-029-OKZ049-053>076-131200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
100 PM CST FRI MAR 12 1999

...MAJOR STORM SYSTEM WILL AFFECT EASTERN OKLAHOMA AND NORTHWEST
ARKANSAS THROUGH SATURDAY...

ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THROUGH TONIGHT ACROSS
SOUTHEAST OKLAHOMA AND WEST CENTRAL ARKANSAS.

.SYNOPSIS...
A STRONG UPPER LEVEL STORM WILL MOVE FROM WESTERN NEW MEXICO INTO WEST
TEXAS THROUGH TONIGHT...THEN INTO WESTERN OKLAHOMA BY EARLY SATURDAY.
AS THE UPPER LEVEL STORM APPROACHES...SURFACE LOW PRESSURE ORGANIZING TO
THE SOUTH ACROSS TEXAS WILL MOVE EAST.  THIS STORM SYSTEM WILL PRODUCE
A VARIETY OF INCLEMENT WEATHER ACROSS THE AREA.

WIDESPREAD RAIN WITH EMBEDDED THUNDERSTORMS WILL CONTINUE TO SPREAD
ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS INTO TONIGHT.  THE
PRECIPITATION WILL EVENTUALLY CHANGE OVER TO SNOW...OR A RAIN SNOW MIX
BEGINNING IN AREAS TO THE NORTHWEST OF TULSA...THEN DEVELOPING FURTHER
TO THE SOUTH AND EAST DURING THE NIGHT AND EARLY SATURDAY.

WIDESPREAD RAINFALL AMOUNTS OF 1 TO 2 INCH WILL ALSO OCCUR WITH THIS
SYSTEM THROUGH TONIGHT WITH ISOLATED HIGHER AMOUNTS POSSIBLE.  IF
RAINFALL BECOMES HEAVIER THAN ANTICIPATED...SOME FLOODING PROBLEMS MAY
RESULT.

AS THE SURFACE LOW MOVES INTO FAR EASTERN TEXAS LATER TONIGHT...COLDER
AIR WILL BE DRAWN SOUTH INTO NORTHEAST OKLAHOMA CHANGING THE RAIN TO
SNOW.  THE SNOW MAY BECOME HEAVY AT TIMES IN AREAS TO THE NORTH AND
NORTHWEST OF TULSA.  FOR THIS REASON...A WINTER STORM WATCH HAS BEEN
ISSUED FOR AREAS TO THE NORTH AND NORTHWEST OF TULSA FOR TONIGHT AND
SATURDAY.  PLEASE REFER TO THE OKCWSWTUL PRODUCT FOR MORE INFORMATION
ON THE WINTER STORM WATCH.

THE UPPER LEVEL STORM WILL MOVE ACROSS OKLAHOMA SATURDAY WITH THE RAIN
CHANGING TO SNOW ACROSS A LARGE PORTION OF EASTERN OKLAHOMA AND
NORTHWEST ARKANSAS BEFORE THE PRECIPITATION ENDS LATER SATURDAY NIGHT.
THERE IS SOME POTENTIAL FOR ACCUMULATIONS SOUTH OF THE WINTER STORM
WATCH AREA...BUT AMOUNTS SHOULD BE LESS THAN THOSE SEEN TO THE NORTH.

.DISCUSSION...
STRONG TO SEVERE THUNDERSTORMS WILL CONTINUE INTO THIS EVENING IN THE
VICINITY OF THE SURFACE LOW OFF TO THE SOUTH.  THESE STORMS WILL
CONTINUE TO MOVE NORTHEAST TOWARD SOUTHEAST OKLAHOMA BUT WILL BE
WEAKENING AS THEY MOVE DEEPER INTO THE COLD AIR IN PLACE ACROSS SOUTHERN
OKLAHOMA AND NORTHERN TEXAS.  AN ISOLATED STORM OR TWO MAY REMAIN STRONG
ENOUGH AS THEY CROSS THE RED RIVER TO PRODUCE HAIL AROUND 3/4 INCH IN
DIAMETER THIS EVENING.  THE HAIL POTENTIAL SHOULD LESSEN AS THE STORMS
CONTINUE MOVING FURTHER NORTHEAST...SO THE THREAT OF ISOLATED SEVERE
THUNDERSTORMS WILL BE CONFINED MAINLY TO AREAS SOUTH OF I-40.

.EMERGENCY AGENCY AND SPOTTER ACTIVATION...
SPOTTER ACTIVATION IS NOT EXPECTED THROUGH TONIGHT...BUT EMERGENCY
MANAGERS ARE URGED TO CHECK LATER FORECASTS AND STATEMENTS WHICH WILL
FURTHER UPDATE THIS DEVELOPING WEATHER SITUATION.