Hail in Kansas, May 5, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
309 PM CDT SAT MAY 5 2001

FORECAST CHALLENGES ARE PRECIP CHANCES TONIGHT AND SUNDAY AND TEMPS
ALL PERIODS.

12Z UPPER AIR MAPS AGAIN SHOWING NORTHERN BRANCH OF WESTERLIES
BANGING INTO THE PACIFIC NORTHWEST. FAIRLY IMPRESSIVE SOUTHERN
BRANCH WITH 110KT 250MB JET AT KBRO AND INTERMEDIATE STREAM AROUND
THE ROCKIES UPPER LOW. 500MB MAP SHOWS IMPRESSIVE WAVE ROUNDING THE
SOUTHWESTERN QUADRANT OF THE LOW WITH 160M HEIGHT FALLS AND -33C
TEMPS ASSOCIATED WITH THE PACIFIC NORTHWEST WAVE. MID LEVEL DRY SLOT
BEHIND LAST NIGHTS WAVE WAS WELL THROUGH THE CWA. BEST MOISTURE AT
850MB HAS PUSHED INTO OUT AS WELL HOWEVER 18Z SOUNDING HAS SHOWN
MOISTURE IS RETURNING AS EVIDENCED BY LOTS OF CUMULUS FROM
WESTERN CWA SOUTHWEST INTO EASTERN NEW MEXICO VIA VISIBLE SATELLITE
IMAGERY. 18Z SURFACE MAP SHOWS A VERY COMPLEX SITUATION MULTIPLE OLD
BOUNDARIES OVER NORTHERN KANSAS AND NEBRASKA, A DRYLINE DEVELOPING
FROM NEAR EHA SOUTH TO NEAR LBB, AND A COLD FRONT FROM THE UPPER LOW
WORKING EAST INTO EASTERN NEW MEXICO.

DRYLINE SHOULD BECOME BETTER DEFINED OVER CENTRAL COUNTIES EARLY
THIS EVENING AND BE THE FOCUS FOR SEVERE CONVECTION. WITH MOISTURE
STILL IN PLACE TO THE WEST, WILL NEED POPS FOR ALL AREAS HOWEVER.
BEST CHANCES WITH THE APPROACHING SHORTWAVE MOVING THROUGH WEST
TEXAS AND NORTHEAST INTO WESTERN OKLAHOMA SHOULD BE OVER THE
SOUTHEAST CWA. EXACT NUMBER OF THE CHANCES WILL LIKELY BE TWEAKED
UNTIL ZONE ISSUANCE, BUT PLANS ARE FOR 60-80 IN THE SOUTHEAST, 40-70
IN THE CENTRAL, AND 30-60 IN THE WEST WITH SEVERE WORDING FOR THE
CENTRAL AND EAST. COLD FRONT WITH THE UPPER SYSTEM SHOULD PASS
THROUGH LATE TONIGHT WITH A BIT DRYER AIR MOVING IN. THUS, DONT
EXPECT LOWS TO VARY MUCH FROM LAST NIGHTS AND GUIDANCE SEEMS
REASONABLE.

UPPER LOW QUICKLY MOVES NORTHEAST SUNDAY WITH COLD FRONT DIVING
SOUTH THROUGH THE HIGH PLAINS FROM PACIFIC NORTHWEST SHORTWAVE. WITH
SOME MOISTURE REMAINING IN PLACE, CANT RULE OUT SCATTERED SHOWERS
AND PERHAPS SOME THUNDER BUT DONT EXPECT MUCH COVERAGE AND WILL
CONTINUE THE GOING SMALL POPS. HIGH TEMPS WILL BE TRICKY WITH SOME
LOCATIONS LIKELY SEEING HIGHS IN THE LATE MORNING TO EARLY
AFTERNOON. WILL GRADIENT HIGHS FROM THE LOWER 60S IN THE NORTHWEST
TO AROUND 70 IN THE SOUTHEAST.

FOR SUNDAY NIGHT AND MONDAY, UPPER RIDGING TO BUILD TO THE WEST WITH
SURFACE HIGH SINKING INTO THE CENTRAL PLAINS. HARD TO RULE OUT WEAK
WAVES COMING DOWN INTO THE REGION IN THE NORTHWEST FLOW, BUT WILL
KEEP THESE PERIODS PRECIP FREE FOR NOW. WITH LITTLE MIXING AND THE
COLD AIR STILL IN PLACE, THINK GUIDANCE HIGHS ARE A BIT WARM.

EXTENDED DISCUSSION...

SIGNIFICANT WEATHER EPISODE IMMINENT. THIS DISCUSSION
MUST BE BRIEF.

FOR DETAILS ON WHAT IS A COMPLICATED SITUATION INVOLVING THE
DYNAMICS OF THE PLANETARY-SCALE, PLEASE REFER TO THE WEEK 2
FORECAST ON OUR LOCAL WEB SITE (WWW.CRH.NOAA.GOV/DDC).
DETAILS ON THE DIFFERENCES IN THE OPERATIONAL GLOBAL NWP CAN BE
FOUND IN THE PMDEPD FROM HPC/NCEP.

THE GIST IS THAT A ROSSBY WAVE RAPID AMPLIFICATION EVENT
IS CURRENTLY IN PROGRESS.  THAT IS WHAT RESULTED IN INITIALLY
A CLOSED MIDDLE/UPPER TROPOSPHERIC CYCLONE ACROSS THE SW STATES.
THAT FEATURE IS NOW BEING EJECTED NEWD.  MODEL SKILL HAS BEEN
SUFFERING FOR ABOUT THE PAST WEEK, AND TODAY THERE IS DIVERGENCE
IN ALL OPERATIONAL GLOBAL NWP SOLUTIONS AFTER ABOUT DAY 3.

AMPLIFIED REGIME WILL DECAY, AND THE MOST SIGNIFICANT LOBE OF THE
POLAR VORTEX WILL BECOME DISPLACED TOWARD NE ASIA.  THE LATTER MAY
BE A RESPONSE TO PERSISTENT AND CURRENTLY INCREASING TROPICAL
CONVECTION ACROSS THE INDIAN AND WEST PACIFIC (PERHAPS THE NEXT
MOIST MJO) OCEANS. GLOBAL ANGULAR MOMENTUM HAS BEEN INCREASING THE
LAST FEW DAYS IN RESPONSE TO THE TROPICAL THUNDERSTORMS.  HENCE
ANOTHER WESTERN US MIDDLE/UPPER TROPOSPHERIC TROUGH SEEMS LIKE A
REAL POSSIBILITY IN ABOUT 7-10 DAYS.  I WILL BASE THE EXTENDED
FORECAST ON THE ECM/AVN AND MRF ENSEMBLE MEAN, EVERYTHING CONSIDERED
SCIENTIFICALLY.

PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE
CONTAINED WITHIN THE DODGE CITY ZONE FORECAST.

DDC 050/065 041/066 042 720
GCK 048/063 038/066 042 620
EHA 048/064 040/068 045 620
LBL 051/065 041/067 043 620
HYS 050/063 038/065 041 720
P28 055/072 045/067 044 820

.DDC...NONE.

POAGE/BERRY